On the discretization of double-bracket flows

Abstract: This paper extends the method of Magnus series to Lie-algebraic equations originating in double-bracket flows. We show that the solution of the isospectral flow Y' = [[Y,N],Y], Y(O) = Y/sub 0/ in Sym(n), can be represented in the form Y(t) = e/sup Omega (t)/Y/sub 0/e/sup - Omega (1)/, where the Taylor expansion of Omega can be constructed explicitly, term-by-term, identifying individual expansion terms with certain rooted trees with bicolor leaves. This approach is extended to other Lie-algebraic equations that can be appropriately expressed in terms of a finite "alphabet"

double-bracket flows discretization
Magnus series
Lie-algebraic equations
isospectral flow
Taylor expansion
bicolor leaves


Data allocation on wireless broadcast channels for efficient query processing

Abstract: Data broadcast is an excellent method for efficient data dissemination in the mobile computing environment. The application domain of data broadcast will be widely expanded in the near future, where the client is expected to perform complex queries or transactions on the broadcast data. To reduce the access latency for processing the complex query, it is beneficial to place the data accessed in a query close to each other on the broadcast channel. In this paper, we propose an efficient algorithm to determine the allocation of the data on the broadcast channel such that frequently co-accessed data are not only allocated close to each other, but also in a particular order which optimizes the performance of query processing. Our mechanism is based on the well-known problem named optimal linear ordering. Experiments are performed to justify the benefit of our approach

database broadcasting
query processing
access time
tuning time
broadcast program
wireless broadcast channels
access latency
mobile computing


Action aggregation and defuzzification in Mamdani-type fuzzy systems

Abstract: Discusses the issues of action aggregation and defuzzification in Mamdani-type fuzzy systems. The paper highlights the shortcomings of defuzzification techniques associated with the customary interpretation of the sentence connective 'and' by means of the set union operation. These include loss of smoothness of the output characteristic and inaccurate mapping of the fuzzy response. The most appropriate procedure for aggregating the outputs of different fuzzy rules and converting them into crisp signals is then suggested. The advantages in terms of increased transparency and mapping accuracy of the fuzzy response are demonstrated

action aggregation
defuzzification
Mamdani-type fuzzy systems
sentence connective
set union operation
fuzzy rules
fuzzy response
crisp signals
transparency
mapping accuracy


The incredible shrinking pipeline

Abstract: We look at the harsh facts concerning the percentage of degrees awarded in CS to women. We study the trend of degrees awarded in CS since 1980, and compare the trend in CS to other science and engineering disciplines. We consider the relationship between the percentage of degrees awarded to women by a CS department and the college the CS department is within. We find that CS departments in engineering colleges graduate, on average, proportionately fewer women than CS departments in non-engineering colleges. We request that the community respond to the facts and speculations presented in this article

pipeline shrinkage problem
women
computer science degrees
science
engineering


Integrated optical metrology controls post etch CDs

Abstract: Control of the transistor gate critical dimension (CD) on the order of a few nanometers is a top priority in many advanced IC fabs. Each nanometer deviation from the target gate length translates directly into the operational speed of these devices. However, using in-line process control by linking the lithography and etch tools can improve CD performance beyond what each individual tool can achieve. The integration of optical CD metrology tools to etch mainframes can result in excellent etcher stability and better control of post-etch CDs

integrated optical metrology
transistor gate critical dimension
post etch CD control
IC fabs
target gate length
operational speed
optical CD metrology tools
etch mainframes
etcher stability
in-line process control
lithography tools
CD performance
photolithography


Speedera: Web without the wait

Abstract: There's no greater testament to the utility of the Internet than the fact that hundreds of millions of people worldwide are willing to wait for Web pages as they build incrementally on screen. But while users may put up with the "World Wide Wait," they definitely don't like it. That's where Content Delivery Networks come in. CDNs can't turn a footpath into a freeway, but they can help data in transit take advantage of shortcuts and steer clear of traffic jams. And while enhancing the responsiveness of Web interaction, CDNs also enhance the prospects of their clients, who need engaged visitors to keep their Web-based business models afloat. "Our mission is to improve the quality of the Internet experience for end-users," says Gordon Smith, vice president of marketing at Speedera Networks in Santa Clara, California, "and to enable Web-site operators to provide better delivery quality, performance, scalability, and security through an outsourced service model that slashes IT costs."

Content Delivery Networks
Web-site operators
delivery quality
scalability
security
outsourced service model
World Wide Web
Web interaction
Web-based business models
Internet experience


A variable-stepsize variable-order multistep method for the integration of perturbed linear problems

Abstract: G. Scheifele (1971) wrote the solution of a perturbed oscillator as an expansion in terms of a new set of functions, which extends the monomials in the Taylor series of the solution. Recently, P. Martin and J.M. Ferrandiz (1997) constructed a multistep code based on the Scheifele technique, and it was generalized by D.J. Lopez and P. Martin (1998) for perturbed linear problems. However, the remarked codes are constant steplength methods, and efficient integrators must be able to change the steplength. In this paper we extend the ideas of F.T. Krogh (1974) from Adams methods to the algorithm proposed by Lopez and Martin, and we show the advantages of the new code in perturbed problems


Abstract: With the advent of Internet technology, it is now feasible to provide effective and efficient helpdesk service over the global Internet to meet customers' requirements and satisfaction. In this research, we have designed and developed a Web-based intelligent helpdesk-support environment, WebHotLine, to support the customer service centre of a large multinational corporation in the electronics industry. The paper describes the basic architecture of the environment that supports the major functions of Web-based fault information retrieval, online multilingual translation capability, different operating modes of video-conferencing for enhanced support and direct intelligent fault diagnosis by customers or customer support engineers. As a result, WebHotLine helps to save cost in eliminating the expensive overseas telephone charges, reduction in machine down time and number of on-site visits by service engineers as in traditional helpdesk environment


Permission grids: practical, error-bounded simplification

Abstract: We introduce the permission grid, a spatial occupancy grid which can be used to guide almost any standard polygonal surface simplification algorithm into generating an approximation with a guaranteed geometric error bound. In particular, all points on the approximation are guaranteed to be within some user-specified distance from the original surface. Such bounds are notably absent from many current simplification methods, and are becoming increasingly important for applications in scientific computing and adaptive level of detail control. Conceptually simple, the permission grid defines a volume in which the approximation must lie, and does not permit the underlying simplification algorithm to generate approximations outside the volume. The permission grid makes three important, practical improvements over current error-bounded simplification methods. First, it works on arbitrary triangular models, handling all manners of mesh degeneracies gracefully. Further, the error tolerance may be easily expanded as simplification proceeds, allowing the construction of an error-bounded level of detail hierarchy with vertex correspondences among all levels of detail. And finally, the permission grid has a representation complexity independent of the size of the input model, and a small running time overhead, making it more practical and efficient than current methods with similar guarantees


Access privilege management in protection systems

Abstract: We consider the problem of managing access privileges on protected objects. We associate one or more locks with each object, one lock for each access right defined by the object type. Possession of an access right on a given object is certified by possession of a key for this object, if this key matches one of the object locks. We introduce a number of variants to this basic key-lock technique. Polymorphic access rights make it possible to decrease the number of keys required to certify possession of complex access privileges that are defined in terms of several access rights. Multiple locks on the same access right allow us to exercise forms of selective revocation of access privileges. A lock conversion function can be used to reduce the number of locks associated with any given object to a single lock. The extent of the results obtained is evaluated in relation to alternative methodologies for access privilege management

complex access privilege possession certification


Wavelet-based level-of-detail representation of 3D objects

Abstract: In this paper, we propose a 3D object LOD (Level of Detail) modeling system that constructs a mesh from range images and generates the mesh of various LOD using the wavelet transform. In the initial mesh generation, we use the marching cube algorithm. We modify the original algorithm to apply it to construct the mesh from multiple range images efficiently. To get the base mesh we use the decimation algorithm which simplifies a mesh with preserving the topology. Finally, when reconstructing new mesh which is similar to initial mesh we calculate the wavelet coefficients by using the wavelet transform. We solve the critical problem of wavelet-based methods - the surface crease problem - by using the mesh simplification as the base mesh generation method

3D object level of detail modeling system


Reproducibility of mammary gland structure during repeat setups in a supine position

Abstract: Purpose: In breast conserving therapy, complete excision of the tumor with an acceptable cosmetic outcome depends on accurate localization in terms of both the position of the lesion and its extent. We hypothesize that preoperative contrast-enhanced magnetic resonance (MR) imaging of the patient in a supine position may be used for accurate tumor localization and marking of its extent immediately prior to surgery. Our aims in this study are to assess the reproducibility of mammary gland structure during repeat setups in a supine position, to evaluate the effect of a breast immobilization device, and to derive reproducibility margins that take internal tissue shifts into account occurring between repeat setups. Materials Methods: The reproducibility of mammary gland structure during repeat setups in a supine position is estimated by quantification of tissue shifts in the breasts of healthy volunteers between repeat MR setups. For each volunteer fiducials are identified and registered with their counter locations in corresponding MR volumes. The difference in position denotes the shift of breast tissue. The dependence on breast volume and the part of the breast, as well as the effect of a breast immobilization cast are studied. Results: The tissue shifts are small with a mean standard deviation on the order of 1.5 mm, being slightly larger in large breasts (V>1000 cm/sup 3/), and in the posterior part (toward the pectoral muscle) of both small and large breasts. The application of a breast immobilization cast reduces the tissue shifts in large breasts. A reproducibility margin on the order of 5 mm will take the internal tissue shifts into account that occur between repeat setups. Conclusion: The results demonstrate a high reproducibility of mammary gland structure during repeat setups in a supine position

contrast-enhanced magnetic resonance imaging


A 3-stage pipelined architecture for multi-view images decoder

Abstract: In this paper, we proposed the architecture of the decoder which implements the multi-view images decoding algorithm. The study of the hardware structure of the multi-view image processing has not been accomplished. The proposed multi-view images decoder operates in a three stage pipelined manner and extracts the depth of the pixels of the decoded image every clock. The multi-view images decoder consists of three modules, Node selector which transfers the value of the nodes repeatedly and Depth Extractor which extracts the depth of each pixel from the four values of the nodes and Affine Transformer which generates the projecting position on the image plane from the values of the pixels and the specified viewpoint. The proposed architecture is designed and simulated by the Max+PlusII design tool and the operating frequency is 30 MHz. The image can be constructed in a real time by the decoder with the proposed architecture

three-stage pipelined architecture
multi-view images decoder
hardware structure
pixel depth
node selector
depth extractor
affine transformer
viewpoint
Max+PlusII design tool
operating frequency
30 MHz


Philadelphia stock exchange taps TimesTen for database technology

Abstract: PHLX rolls out Equity Options AutoQuote System to traders as the first application to leverage its enhanced data architecture

Philadelphia stock exchange
TimesTen
Equity Options AutoQuote System
data architecture


Molecular descriptor selection combining genetic algorithms and fuzzy logic: application to database mining procedures

Abstract: A new algorithm, devoted to molecular descriptor selection in the context of data mining problems, has been developed. This algorithm is based on the concepts of genetic algorithms (GA) for descriptor hyperspace exploration and combined with a stepwise approach to get local convergence. Its selection power was evaluated by a fitness function derived from a fuzzy clustering method. Different training and test sets were randomly generated at each GA generation. The fitness score was derived by combining the scores of the training and test sets. The ability of the proposed algorithm to select relevant subsets of descriptors was tested on two data sets. The first one, an academic example, corresponded to the artificial problem of Bullseye, the second was a real data set including 114 olfactory compounds divided into three odor categories. In both cases, the proposed method allowed to improve the separation between the different data set classes

molecular descriptor selection
database mining
data mining
genetic algorithms
fuzzy clustering method
fuzzy logic
descriptor hyperspace exploration
local convergence
stepwise approach
fitness function
test sets
training sets
fitness score
Bullseye
olfactory compounds
odor categories


An intelligent tutoring system for a power plant simulator

Abstract: In this paper, an intelligent tutoring system (ITS) is proposed for a power plant simulator. With a well designed ITS, the need for an instructor is minimized and the operator may readily and efficiently take, in real-time, the control of simulator with appropriate messages he(she) gets from the tutoring system. Using SIMULINK and based on object oriented programming (OOP) and C programming language, a fossil-fuelled power plant simulator with an ITS is proposed. Promising results are demonstrated for a typical power plant

fossil-fuelled power plant simulator
intelligent tutoring system
SIMULINK
object oriented programming
control simulation
C programming language
CAI


Implementation and evaluation of HPF/SX V2

Abstract: We are developing HPF/SX V2, a High Performance Fortran (HPF) compiler for vector parallel machines. It provides some unique extensions as well as the features of HPF 2.0 and HPF/JA. In particular, this paper describes four of them: (1) the ON directive of HPF 2.0; (2) the REFLECT and LOCAL directives of HPF/JA; (3) vectorization directives; and (4) automatic parallelization. We evaluate these features through some benchmark programs on NEC SX-5. The results show that each of them achieved a 5-8 times speedup in 8-CPU parallel execution and the four features are useful for vector parallel execution. We also evaluate the overall performance of HPF/SX V2 by using over 30 well-known benchmark programs from HPFBench, APR Benchmarks, GENESIS Benchmarks, and NAS Parallel Benchmarks. About half of the programs showed good performance, while the other half suggest weakness of the compiler, especially on its runtimes. It is necessary to improve them to put the compiler to practical use

HPF/SX V2
High Performance Fortran compiler
vector parallel machines
benchmark
parallelization
compiler


HPCVIEW: a tool for top-down analysis of node performance

Abstract: It is increasingly difficult for complex scientific programs to attain a significant fraction of peak performance on systems that are based on microprocessors with substantial instruction-level parallelism and deep memory hierarchies. Despite this trend, performance analysis and tuning tools are still not used regularly by algorithm and application designers. To a large extent, existing performance tools fail to meet many user needs and are cumbersome to use. To address these issues, we developed HPCVIEW - a toolkit for combining multiple sets of program profile data, correlating the data with source code, and generating a database that can be analyzed anywhere with a commodity Web browser. We argue that HPCVIEW addresses many of the issues that have limited the usability and the utility of most existing tools. We originally built HPCVIEW to facilitate our own work on data layout and optimizing compilers. Now, in addition to daily use within our group, HPCVIEW is being used by several code development teams in DoD and DoE laboratories as well as at NCSA

HPCView
top-down analysis
node performance
complex scientific programs
peak performance
instruction-level parallelism
deep memory hierarchies
performance analysis
source code
commodity Web browser
data layout
optimizing compilers
software tools
binary analysis


Optical actuation of a bistable MEMS

Abstract: This paper presents an optical actuation scheme for MEMS devices based on the well-established fact that light possesses momentum, and hence, imparts a force equal to 2 W/c when reflected by a surface. Here, W is the total power of the reflected light, and c is the speed of light. Radiation pressure, as it is known, is nearly insignificant for most macroscale applications, but it can be quite significant for MEMS devices. In addition, light actuation offers a new paradigm. First, intersecting light beams do not interfere, in contrast to electrical conductors, which short when they come into contact. Second, light can operate in high temperature and high radiation environments far outside the capability of solid state electronic components. This actuation method is demonstrated, both in air and in vacuum, by switching the state of a bistable MEMS device. The associated heat transfer model is also presented

bistable MEMS
optical actuation scheme
radiation pressure
MEMS devices
intersecting light beams
high temperature environments
high radiation environments
heat transfer model


Network intrusion and fault detection: a statistical anomaly approach

Abstract: With the advent and explosive growth of the global Internet and electronic commerce environments, adaptive/automatic network/service intrusion and anomaly detection in wide area data networks and e-commerce infrastructures is fast gaining critical research and practical importance. We present and demonstrate the use of a general-purpose hierarchical multitier multiwindow statistical anomaly detection technology and system that operates automatically, adaptively, and proactively, and can be applied to various networking technologies, including both wired and wireless ad hoc networks. Our method uses statistical models and multivariate classifiers to detect anomalous network conditions. Some numerical results are also presented that demonstrate that our proposed methodology can reliably detect attacks with traffic anomaly intensity as low as 3-5 percent of the typical background traffic intensity, thus promising to generate an effective early warning

hierarchical multitier statistical anomaly detection

P P P M M R M M U U P P P P R R R P P P P P


Sufficient conditions on nonemptiness and boundedness of the solution set of the P/sub 0/ function nonlinear complementarity problem

Abstract: The P/sub 0/ function nonlinear complementarity, problem (NCP) has attracted a lot of attention among researchers. Various assumed conditions, which ensure that the NCP has a solution have been proposed. In this paper, by using the notion of an exceptional family of elements we develop a sufficient condition which ensures that the solution set of the P/sub 0/ function NCP is nonempty and bounded. In particular, we prove that many existing assumed conditions imply this sufficient condition. Thus, these conditions imply that the solution set of the P/sub 0/ function NCP is nonempty and bounded. In addition, we also prove directly that a few existence conditions imply that the solution set of the P/sub 0/ function NCP is bounded


Adjoint-based optimization of steady suction for disturbance control in incompressible flows

Abstract: The optimal distribution of steady suction needed to control the growth of single or multiple disturbances in quasi-three-dimensional incompressible boundary layers on a flat plate is investigated. The evolution of disturbances is analysed in the framework of the parabolized stability equations (PSE). A gradient-based optimization procedure is used and the gradients are evaluated using the adjoint of the parabolized stability equations (APSE) and the adjoint of the boundary layer equations (ABLE). The accuracy of the gradient is increased by introducing a stabilization procedure for the PSE. Results show that a suction peak appears in the upstream part of the suction region for optimal control of Tollmien-Schlichting (T-S) waves, steady streamwise streaks in a two-dimensional boundary layer and oblique waves in a quasi-three-dimensional boundary layer subject to an adverse pressure gradient. The mean flow modifications due to suction are shown to have a stabilizing effect similar to that of a favourable pressure gradient. It is also shown that the optimal suction distribution for the disturbance of interest reduces the growth rate of other perturbations. Results for control of a steady cross-flow mode in a three-dimensional boundary layer subject to a favourable pressure gradient show that not even large amounts of suction can completely stabilize the disturbance

quasithree-dimensional incompressible boundary layers


Estimation of thermal coefficients of magneto-optical media

Abstract: Previously we described a method for estimating the thermal conductivity of magneto-optic recording media. The method relies on identifying the laser power that brings the maximum temperature of the TbFeCo layer to as high as the Curie temperature. We extensively use a similar method to estimate the heat capacity of a dielectric layer, a TbFeCo layer, and an aluminum alloy layer of magneto-optic recording media. Measurements are conducted on static disks with a beam of light focused on a TbFeCo layer. The method has the advantage of thermal diffusion depending on a multilayer structure and irradiation time

thermal coefficients
magneto-optical media
thermal conductivity
laser power
maximum temperature
TbFeCo layer
Curie temperature
dielectric layer
heat capacity
aluminum alloy layer
magneto-optic recording media
static disks
light focusing
thermal diffusion
multilayer structure
irradiation time
TbFeCo


Experimental investigations on monitoring and control of induction heating process for semi-solid alloys using the heating coil as sensor

Abstract: A method of monitoring the state of metal alloys during induction heating and control of the heating process utilizing the heating coil itself as a sensor is proposed, and its usefulness and effectiveness were experimentally investigated using aluminium A357 billets for the semi-solid metal (SSM) casting processes. The impedance of the coil containing the billet was continuously measured by the proposed method in the temperature range between room temperature and 700 degrees C. It was found that the reactance component of the impedance varied distinctively according to the billet state and could clearly monitor the deformation of the billet, while the resistance component increased with temperature, reflecting the variation of the resistivity of the billet which has strong correlation to the solid/liquid fraction of the billets. The measured impedance is very sensitive to the billet states such as temperature, deformation and solid/liquid fraction and could be used as a parameter to monitor and control the heating process for SSMs

induction heating process
process monitoring
process control
semisolid alloys
semisolid metal casting
heating coil sensor
coil impedance
reactance component
billet state
billet deformation
resistance component
resistivity variation
solid/liquid fraction
solenoid coil
20 to 700 C


Optical setup and analysis of disk-type photopolymer high-density holographic storage

Abstract: A relatively simple scheme for disk-type photopolymer high-density holographic storage based on angular and spatial multiplexing is described. The effects of the optical setup on the recording capacity and density are studied. Calculations and analysis show that this scheme is more effective than a scheme based on the spatioangular multiplexing for disk-type photopolymer high-density holographic storage, which has a limited medium thickness. Also an optimal beam recording angle exists to achieve maximum recording capacity and density


Rational systems exhibit moderate risk aversion with respect to "gambles" on variable-resolution compression

Abstract: In an embedded wavelet scheme for progressive transmission, a tree structure naturally defines the spatial relationship on the hierarchical pyramid. Transform coefficients over each tree correspond to a unique local spatial region of the original image, and they can be coded bit-plane by bit-plane through successive-approximation quantization. After receiving the approximate value of some coefficients, the decoder can obtain a reconstructed image. We show a rational system for progressive transmission that, in absence of a priori knowledge about regions of interest, chooses at any truncation time among alternative trees for further transmission in such a way as to avoid certain forms of behavioral inconsistency. We prove that some rational transmission systems might exhibit aversion to risk involving "gambles" on tree-dependent quality of encoding while others favor taking such risks. Based on an acceptable predictor for visual distinctness from digital imagery, we demonstrate that, without any outside knowledge, risk-prone systems as well as those with strong risk aversion appear in capable of attaining the quality of reconstructions that can be achieved with moderate risk-averse behavior

hierarchical pyramid spatial relationship

progressive transmission utility functions

P P P P P P R P P P P P R P R P P P R U U M U


Abacus, EFI and anti-virus

Abstract: The Extensible Firmware Interface (EFI) standard emerged as a logical step to provide flexibility and extensibility to boot sequence processes, enabling the complete abstraction of a system's BIOS interface from the system's hardware. In doing so, this provided the means of standardizing a boot-up sequence, extending device drivers and boot time applications' portability to non PC-AT-based architectures, including embedded systems like Internet appliances, TV Internet set-top boxes and 64-bit Itanium platforms

Extensible Firmware Interface standard
anti-virus
embedded systems


X-Rite: more than a graphic arts company

Abstract: Although it is well known as a maker of densitometers and spectrophotometers, X-Rite is active in measuring light and shape in many industries. Among them are automobile finishes, paint and home improvements, scientific instruments, optical semiconductors and even cosmetic dentistry


Automated post bonding inspection by using machine vision techniques

Abstract: Inspection plays an important role in the semiconductor industry. In this paper, we focus on the inspection task after wire bonding in packaging. The purpose of wire bonding (W/B) is to connect the bond pads with the lead fingers. Two major types of defects are (1) bonding line missing and (2) bonding line breakage. The numbers of bonding lines and bonding balls are used as the features for defect classification. The proposed method consists of image preprocessing, orientation determination, connection detection, bonding line detection, bonding ball detection, and defect classification. The proposed method is simple and fast. The experimental results show that the proposed method can detect the defects effectively

semiconductor industry
IC manufacturing
automated post bonding inspection
machine vision
wire bonding
packaging
bond pad connection
lead fingers
bonding line missing
bonding line breakage
bonding balls
defect classification
image preprocessing
orientation determination
connection detection
bonding line detection
bonding ball detection


IT at the heart of joined-up policing

Abstract: Police IT is to shift from application-focused to component-based technology. The change of strategy, part of the Valiant Programme, will make information held by individual forces available on a national basis


The 3D visibility complex

Abstract: Visibility problems are central to many computer graphics applications. The most common examples include hidden-part removal for view computation, shadow boundaries, mutual visibility of objects for lighting simulation. In this paper, we present a theoretical study of 3D visibility properties for scenes of smooth convex objects. We work in the space of light rays, or more precisely, of maximal free segments. We group segments that "see" the same object; this defines the 3D visibility complex. The boundaries of these groups of segments correspond to the visual events of the scene (limits of shadows, disappearance of an object when the viewpoint is moved, etc.). We provide a worst case analysis of the complexity of the visibility complex of 3D scenes, as well as a probabilistic study under a simple assumption for "normal" scenes. We extend the visibility complex to handle temporal visibility. We give an output-sensitive construction algorithm and present applications of our approach

3D visibility complex
computer graphics
hidden-part removal
view computation
shadow boundaries
mutual object visibility
lighting simulation
smooth convex objects
light rays
maximal free segments
visual events
worst case complexity analysis
probabilistic study
normal scenes
temporal visibility
output-sensitive construction algorithm


PKI: coming to an enterprise near you?

Abstract: For many years public key infrastructure (PKI) deployments were the provenance of governments and large, security-conscious corporations and financial institutions. These organizations have the financial and human resources necessary to successfully manage the complexities of a public key system. Lately however, several forces have converged to encourage a broader base of enterprises to take a closer look at PKI. These forces are discussed. PKI vendors are now demonstrating to customers how they can make essential business applications faster and more efficient by moving them to the Internet-without sacrificing security. Those applications usually include secure remote access, secure messaging, electronic document exchange, transaction validation, and network authentication. After a brief discussion of PKI basics the author reviews various products available on the market

PKI
business-critical applications
public key infrastructure
e-commerce
IPSec VPNs
PKI vendors
security
secure remote access
secure messaging
electronic document exchange
transaction validation
network authentication
Baltimore Technologies
Entrust
GeoTrust
RSA Security
VeriSign


Speaker adaptive modeling by vocal tract normalization

Abstract: This paper presents methods for speaker adaptive modeling using vocal tract normalization (VTN) along with experimental tests on three databases. We propose a new training method for VTN: By using single-density acoustic models per HMM state for selecting the scale factor of the frequency axis, we avoid the problem that a mixture-density tends to learn the scale factors of the training speakers and thus cannot be used for selecting the scale factor. We show that using single Gaussian densities for selecting the scale factor in training results in lower error rates than using mixture densities. For the recognition phase, we propose an improvement of the well-known two-pass strategy: by using a non-normalized acoustic model for the first recognition pass instead of a normalized model, lower error rates are obtained. In recognition tests, this method is compared with a fast variant of VTN. The two-pass strategy is an efficient method, but it is suboptimal because the scale factor and the word sequence are determined sequentially. We found that for telephone digit string recognition this suboptimality reduces the VTN gain in recognition performance by 30% relative. In summary, on the German spontaneous speech task Verbmobil, the WSJ task and the German telephone digit string corpus SieTill, the proposed methods for VTN reduce the error rates significantly

speaker adaptive modeling
vocal tract normalization
databases
training method
single-density acoustic models
HMM state
frequency scale factor
training speakers
single Gaussian densities
training results
error rate reduction
two-pass strategy
nonnormalized acoustic model
word sequence
telephone digit string recognition
German spontaneous speech task
Verlimobil
WSJ task
German telephone digit string corpus
SieTill


Rank tests of association for exchangeable paired data

Abstract: We describe two rank tests of association for paired exchangeable data motivated by the study of lifespans in twins. The pooled sample is ranked. The nonparametric test of association is based on R/sup +/, the sum of the smaller within-pair ranks. A second measure L/sup +/ is the sum of within-pair rank products. Under the null hypothesis of within-pair independence, the two test statistics are approximately normally distributed. Expressions for the exact means and variances of R/sup +/ and L/sup +/ are given. We describe the power of these two statistics under a close alternative hypothesis to that of independence. Both the R/sup +/ and L/sup +/ tests indicate nonparametric statistical evidence of positive association of longevity in identical twins and a negligible relationship between the lifespans of fraternal twins listed in the Danish twin registry. The statistics are also applied to the analysis of a clinical trial studying the time to failure of ventilation tubes in children with bilateral otitis media

rank tests
association
paired exchangeable data
twin lifespans
pooled sample
nonparametric test
within-pair ranks
within-pair rank products
null hypothesis
within-pair independence
test statistics
exact means
exact variances
nonparametric statistical evidence
longevity
identical twins
fraternal twins
Danish twin registry
clinical trial
ventilation tube failure time
bilateral otitis media

P P P R P P P P P P P P R P P P P P P R P


National learning systems: a new approach on technological change in late industrializing economies and evidences from the cases of Brazil and South Korea

Abstract: The paper has two intertwined parts. The first one is a proposal for a conceptual and theoretical framework to understand technical change in late industrializing economies. The second part develops a kind of empirical test of the usefulness of that new framework by means of a comparative study of the Brazilian and South Korean cases. All the four types of macroevidences of the technical change processes of Brazil and Korea corroborate, directly or indirectly, the hypothesis of the existence of actual cases of national learning systems (NLSs) of passive and active nature, as it is shown to be the cases of Brazil and South Korea, respectively. The contrast between the two processes of technical change prove remarkable, despite both processes being essentially confined to learning. The concepts of passive and active NLSs show how useful they are to apprehend the diversity of those realities, and, consequently, to avoid, for instance, interpretations that misleadingly suppose (based on conventional economic theory) that those countries have a similar lack of technological dynamism

national learning systems
technological change
late industrializing economies
Brazil
South Korea
national innovation system


Optimization of element-by-element FEM in HPF 1.1

Abstract: In this study, Poisson's equation is numerically evaluated by the element-by-element (EBE) finite-element method in a parallel environment using HPF 1.1 (High-Performance Fortran). In order to achieve high parallel efficiency, the data structures have been altered to node-based data instead of mixtures of node- and element-based data, representing a node-based EBE finite-element scheme (nEBE). The parallel machine used in this study was the NEC SX-4, and experiments were performed on a single node having 32 processors sharing common memory. The HPF compiler used in the experiments is HPF/SX Rev 2.0 released in 1997 (unofficial), which supports HPF 1.1. Models containing approximately 200 000 and 1,500,000 degrees of freedom were analyzed in order to evaluate the method. The calculation time, parallel efficiency, and memory used were compared. The performance of HPF in the conjugate gradient solver for the large model, using the NEC SX-4 compiler option-noshrunk, was about 85% that of the message passing interface

finite element method
parallel programs
Poisson equation
HPF compiler
conjugate gradient solver
message passing
element-by-element
HPF


Dynamic neighborhood structures in parallel evolution strategies

Abstract: Parallelizing is a straightforward approach to reduce the total computation time of evolutionary algorithms. Finding an appropriate communication network within spatially structured populations for improving convergence speed and convergence probability is a difficult task. A new method that uses a dynamic communication scheme in an evolution strategy will be compared with conventional static and dynamic approaches. The communication structure is based on a so-called diffusion model approach. The links between adjacent individuals are dynamically chosen according to deterministic or probabilistic rules. Due to self-organization effects, efficient and stable communication structures are established that perform robustly and quickly on a multimodal test function

evolutionary algorithms
multimodal test function
convergence probability
convergence speed
parallel evolutionary algorithms
parallelizing


Modeling and simulation of an ABR flow control algorithm using a virtual source/virtual destination switch

Abstract: The available bit rate (ABR) service class of asynchronous transfer mode networks uses a feedback control mechanism to adapt to varying link capacities. The virtual source/virtual destination (VS/VD) technique offers the possibility of segmenting the otherwise end-to-end ABR control loop into separate loops. The improved feedback delay and control of ABR traffic inside closed segments provide a better performance for ABR connections. This article presents the use of classical linear control theory to model and develop an ABR VS/VD flow control algorithm. Discrete event simulations are used to analyze the behavior of the algorithm with respect to transient behavior and correctness of the control model. Linear control theory offers the means to derive correct choices of parameters and to assess performance issues, such as stability of the system, during the design phase. The performance goals are high link utilization, fair bandwidth distribution, and robust operation in various environments, which are verified by discrete event simulations. The major contribution of this work is the use of analytic methods (linear control theory) to model and design an ABR flow control algorithm tailored for the special layout of a VS/VD switch, and the use of simulation techniques to verify the result


A high-resolution high-frequency monolithic top-shooting microinjector free of satellite drops - part II: fabrication, implementation, and characterization

Abstract: For pt. I, see ibid., vol. 11, no. 5, p. 427-36 (2002). Describes the fabrication, implementation and characterization of a thermal driven microinjector, featuring a bubble check valve and monolithic fabrication. Microfabrication of this microinjector is based on bulk/surface-combined micromachining of the silicon wafer, free of the bonding process that is commonly used in the fabrication of commercial printing head, so that even solvents and fuels can be ejected. Droplet ejection sequences of two microinjectors have been studied along with a commercial inkjet printhead for comparison. The droplet ejection of our microinjector with 10 mu m diameter nozzle has been characterized at a frequency over 35 kHz, at least 3 times higher than those of commercial counterparts. The droplet volume from this device is smaller than 1 pl, 10 times smaller than those of commercial inkjets employed in the consumer market at the time of testing. Visualization results have verified that our design, although far from being optimized, operates in the frequency several times higher than those of commercial products and reduces the crosstalk among neighboring chambers

monolithic top-shooting microinjector
satellite drops
thermal driven microinjector
bubble check valve
bulk/surface-combined micromachining
bonding process
inkjet printhead
nozzle
droplet volume
consumer market
crosstalk
10 micron
35 kHz


Approximation theory of fuzzy systems based upon genuine many-valued implications - MIMO cases

Abstract: It is constructively proved that the multi-input-multi-output fuzzy systems based upon genuine many-valued implications are universal approximators (they are called Boolean type fuzzy systems in this paper). The general approach to construct such fuzzy systems is given, that is, through the partition of the output region (by the given accuracy). Two examples are provided to demonstrate the way in which fuzzy systems are designed to approximate given functions with a given required approximation accuracy

multi-input-multi-output fuzzy systems
Boolean type fuzzy systems
fuzzy systems
many-valued implication
universal approximator


Entanglement measures with asymptotic weak-monotonicity as lower (upper) bound for the entanglement of cost (distillation)

Abstract: We propose entanglement measures with asymptotic weak-monotonicity. We show that a normalized form of entanglement measures with the asymptotic weak-monotonicity are lower (upper) bound for the entanglement of cost (distillation)

entanglement measures
asymptotic weak-monotonicity
entanglement of cost
distillation


Greenberger-Horne-Zeilinger paradoxes for many qubits

Abstract: We construct Greenberger-Horne-Zeilinger (GHZ) contradictions for three or more parties sharing an entangled state, the dimension of each subsystem being an even integer d. The simplest example that goes beyond the standard GHZ paradox (three qubits) involves five ququats (d = 4). We then examine the criteria that a GHZ paradox must satisfy in order to be genuinely M partite and d dimensional

Greenberger-Horne-Zeilinger paradoxes
many qubits
GHZ contradictions
entangled state
GHZ paradox


Development and evaluation of a case-based reasoning classifier for prediction of breast biopsy outcome with BI-RADS/sup TM/ lexicon

Abstract: Approximately 70-85% of breast biopsies are performed on benign lesions. To reduce this high number of biopsies performed on benign lesions, a case-based reasoning (CBR) classifier was developed to predict biopsy results from BI-RADS/sup TM/ findings. We used 1433 (931 benign) biopsy-proven mammographic cases. CBR similarity was defined using either the Hamming or Euclidean distance measure over case features. Ten features represented each case: calcification distribution, calcification morphology, calcification number, mass margin, mass shape, mass density, mass size, associated findings, special cases, and age. Performance was evaluated using Round Robin sampling, Receiver Operating Characteristic (ROC) analysis, and bootstrap. To determine the most influential features for the CBR, an exhaustive feature search was performed over all possible feature combinations (1022) and similarity thresholds. Influential features were defined as the most frequently occurring features in the feature subsets with the highest partial ROC areas (/sub 0.90/AUC). For CBR with Hamming distance, the most influential features were found to be mass margin, calcification morphology, age, calcification distribution, calcification number, and mass shape, resulting in an /sub 0.90/AUC of 0.33. At 95% sensitivity, the Hamming CBR would spare from biopsy 34% of the benign lesions. At 98% sensitivity, the Hamming CBR would spare 27% benign lesions. For the CBR with Euclidean distance, the most influential feature subset consisted of mass margin, calcification morphology, age, mass density, and associated findings, resulting in /sub 0.90/AUC of 0.37. At 95% sensitivity, the Euclidean CBR would spare from biopsy 41% benign lesions. At 98% sensitivity, the Euclidean CBR would spare 27% benign lesions. The profile of cases spared by both distance measures at 98% sensitivity indicates that the CBR is a potentially useful diagnostic tool for the classification of mammographic lesions, by recommending short-term follow-up for likely benign lesions that is in agreement with final biopsy results and mammographer's intuition

Receiver Operating Characteristic analysis

P P R P P P R P P P P P P P P P P P P R P P P P P P P R P


Products and polymorphic subtypes

Abstract: This paper is devoted to a comprehensive study of polymorphic subtypes with products. We first present a sound and complete Hilbert style axiomatization of the relation of being a subtype in presence of to , * type constructors and the For all quantifier, and we show that such axiornatization is not encodable in the system with to , For all only. In order to give a logical semantics to such a subtyping relation, we propose a new form of a sequent which plays a key role in a natural deduction and a Gentzen style calculi. Interestingly enough, the sequent must have the form E implies T, where E is a non-commutative, non-empty sequence of typing assumptions and T is a finite binary tree of typing judgements, each of them behaving like a pushdown store. We study basic metamathematical properties of the two logical systems, such as subject reduction and cut elimination. Some decidability/undecidability issues related to the presented subtyping relation are also explored: as expected, the subtyping over to , *, For all is undecidable, being already undecidable for the to , For all fragment (as proved in [15]), but for the *, For all fragment it turns out to be decidable

polymorphic subtypes
products subtypes
Hilbert style axiomatization
logical semantics
Gentzen style calculi
finite binary tree
pushdown store
metamathernatical properties
decidability


Robust Kalman filter design for discrete time-delay systems

Abstract: The problem of finite- and infinite-horizon robust Kalman filtering for uncertain discrete-time systems with state delay is addressed. The system under consideration is subject to time-varying norm-bounded parameter uncertainty in both the state and output matrices. We develop a new methodology for designing a linear filter such that the error variance of the filter is guaranteed to be within a certain upper bound for any allowed uncertainty and time delay. The solution is given in terms of two Riccati equations. Multiple time-delay systems are also investigated

robust Kalman filter
discrete time-delay systems
uncertain systems
state delay
time-varying parameter uncertainty
norm-bounded parameter uncertainty
state matrices
output matrices
linear filter
Riccati equations
robust state estimation


Developing a hardware and programming curriculum for middle school girls

Abstract: Techbridge provides experiences and resources that would teach girls technology skills as well as excite their curiosity and build their confidence. Funded by the National Science Foundation and sponsored by Chabot Space and Science Center in Oakland, California, Techbridge is a three-year program that serves approximately 200 girls annually. Techbridge is hosted at 8 middle and high schools in Oakland and at the California School for the Blind in Fremont, California generally as an after-school program meeting once a week. Techbridge comes at a critical time in girls' development when girls have many important decisions to make regarding classes and careers, but often lack the confidence and guidance to make the best choices. Techbridge helps girls plan for the next steps to high school and college with its role models and guidance. Techbridge also provides training and resources for teachers, counselors, and families

middle school girls
hardware and programming curriculum
Techbridge
technology skills teaching


Process planning for reliable high-speed machining of moulds

Abstract: A method of generating NC programs for the high-speed milling of moulds is investigated. Forging dies and injection moulds, whether plastic or aluminium, have a complex surface geometry. In addition they are made of steels of hardness as much as 30 or even 50 HRC. Since 1995, high-speed machining has been much adopted by the die-making industry, which with this technology can reduce its use of Sinking Electrodischarge Machining (SEDM). EDM, in general, calls for longer machining times. The use of high-speed machining makes it necessary to redefine the preliminary stages of the process. In addition, it affects the methodology employed in the generation of NC programs, which requires the use of high-level CAM software. The aim is to generate error-free programs that make use of optimum cutting strategies in the interest of productivity and surface quality. The final result is a more reliable manufacturing process. There are two risks in the use of high-speed milling on hardened steels. One of these is tool breakage, which may be very costly and may furthermore entail marks on the workpiece. The other is collisions between the tool and the workpiece or fixtures, the result of which may be damage to the ceramic bearings in the spindles. in order to minimize these risks it is necessary that new control and optimization steps be included in the CAM methodology. There are three things that the firm adopting high-speed methods should do. It should redefine its process engineering, it should systematize access by its CAM programmers to high-speed knowhow, and it should take up the use of process simulation tools. In the latter case, it will be very advantageous to use tools for the estimation of cutting forces. The new work methods proposed in this article have made it possible to introduce high speed milling (HSM) into the die industry. Examples are given of how the technique has been applied with CAM programming re-engineered as here proposed, with an explanation of the novel features and the results

moulds
reliable high-speed machining
process planning
NC programs
high-speed milling
forging dies
injection moulds
complex surface geometry
error-free programs
optimum cutting strategies
productivity
surface quality
hardened steels
tool breakage
tool workpiece collisions
ceramic bearings
CAM methodology
process engineering redefinition
process simulation tools
CAM programming re-engineering
cutting strategies

P P P P P P P P P P P P P P R P P M P P P


What's in a name? [mobile telephony branding]

Abstract: Mobile operators are frantically consolidating businesses into single international brands

mobile telephony
branding
consolidating businesses


Meshed atlases for real-time procedural solid texturing

Abstract: We describe an implementation of procedural solid texturing that uses the texture atlas, a one-to-one mapping from an object's surface into its texture space. The method uses the graphics hardware to rasterize the solid texture coordinates as colors directly into the atlas. A texturing procedure is applied per-pixel to the texture map, replacing each solid texture coordinate with its corresponding procedural solid texture result. The procedural solid texture is then mapped back onto the object surface using standard texture mapping. The implementation renders procedural solid textures in real time, and the user can design them interactively. The quality of this technique depends greatly on the layout of the texture atlas. A broad survey of texture atlas schemes is used to develop a set of general purpose mesh atlases and tools for measuring their effectiveness at distributing as many available texture samples as evenly across the surface as possible. The main contribution of this paper is a new multiresolution texture atlas. It distributes all available texture samples in a nearly uniform distribution. This multiresolution texture atlas also supports MIP-mapped minification antialiasing and linear magnification filtering

real-time procedural solid texturing
meshed atlases
texture atlas
one-to-one mapping
object surface
texture space
graphics hardware
rasterization
solid texture coordinates
colors
rendering
multiresolution texture atlas
linear magnification filtering
MIP-mapped minification antialiasing


Use of SPOT images as a tool for coastal zone management and monitoring of environmental impacts in the coastal zone

Abstract: Modern techniques such as remote sensing have been one of the main factors leading toward the achievement of serious plans regarding coastal management. A multitemporal analysis of land use in certain areas of the Colombian Caribbean Coast is described. It mainly focuses on environmental impacts caused by anthropogenic activities, such as deforestation of mangroves due to shrimp farming. Selection of sensitive areas, percentage of destroyed mangroves, possible endangered areas, etc., are some of the results of this analysis. Recommendations for a coastal management plan in the area have also resulted from this analysis. Some other consequences of the deforestation of mangroves in the coastal zone and the construction of shrimp ponds are also analyzed, such as the increase of erosion problems in these areas and water pollution, among others. The increase of erosion in these areas has also changed part of their morphology, which has been studied by the analysis of SPOT images in previous years. A serious concern exists about the future of these areas. For this reason new techniques like satellite images (SPOT) have been applied with good results, leading to more effective control and coastal management in the area. The use of SPOT images to study changes of the land use of the area is a useful technique to determine patterns of human activities and suggest solutions for severe problems in these areas

coastal zone management
SPOT images
environmental impact monitoring
remote sensing
multitemporal analysis
land use
Colombian Caribbean Coast
anthropogenic activities
mangrove deforestation
shrimp farming
endangered areas
erosion problems
water pollution
satellite images
human activities
supervised classification
sedimentation
shrimp ponds
vectorization
vector overlay


Operations that do not disturb partially known quantum states

Abstract: Consider a situation in which a quantum system is secretly prepared in a state chosen from the known set of states. We present a principle that gives a definite distinction between the operations that preserve the states of the system and those that disturb the states. The principle is derived by alternately applying a fundamental property of classical signals and a fundamental property of quantum ones. The principle can be cast into a simple form by using a decomposition of the relevant Hilbert space, which is uniquely determined by the set of possible states. The decomposition implies the classification of the degrees of freedom of the system into three parts depending on how they store the information on the initially chosen state: one storing it classically, one storing it nonclassically, and the other one storing no information. Then the principle states that the nonclassical part is inaccessible and the classical part is read-only if we are to preserve the state of the system. From this principle, many types of no-cloning, no-broadcasting, and no-imprinting conditions can easily be derived in general forms including mixed states. It also gives a unified view on how various schemes of quantum cryptography work. The principle helps one to derive optimum amount of resources (bits, qubits, and ebits) required in data compression or in quantum teleportation of mixed-state ensembles

partially known quantum states
quantum system
secretly prepared quantum state
classical signals
Hilbert space
degrees of freedom
nonclassical part
quantum cryptography
bits
qubits
ebits
quantum teleportation
mixed-state ensembles


Completeness of timed mu CRL

Abstract: Previously a straightforward extension of the process algebra mu CRL was proposed to explicitly deal with time. The process algebra mu CRL has been especially designed to deal with data in a process algebraic context. Using the features for data, only a minor extension of the language was needed to obtain a very expressive variant of time. Previously it contained syntax, operational semantics and axioms characterising timed mu CRL. It did not contain an in depth analysis of theory of timed mu CRL. This paper fills this gap, by providing soundness and completeness results. The main tool to establish these is a mapping of timed to untimed mu CRL and employing the completeness results obtained for untimed mu CRL

timed mu CRL
completeness
process algebra
operational semantics


A partial converse to Hadamard's theorem on homeomorphisms

Abstract: A theorem by Hadamard gives a two-part condition under which a map from one Banach space to another is a homeomorphism. The theorem, while often very useful, is incomplete in the sense that it does not explicitly specify the family of maps for which the condition is met. Here, under a typically weak additional assumption on the map, we show that Hadamard's condition is met if, and only if, the map is a homeomorphism with a Lipschitz continuous inverse. An application is given concerning the relation between the stability of a nonlinear system and the stability of related linear systems

partial converse
Hadamard theorem
homeomorphisms
Banach space
Lipschitz continuous inverse
nonlinear system stability
linear system stability
linearization
nonlinear feedback systems
nonlinear networks


Evolving robust asynchronous cellular automata for the density task

Abstract: In this paper the evolution of three kinds of asynchronous cellular automata are studied for the density task. Results are compared with those obtained for synchronous automata and the influence of various asynchronous update policies on the computational strategy is described. How synchronous and asynchronous cellular automata behave is investigated when the update policy is gradually changed, showing that asynchronous cellular automata are more adaptable. The behavior of synchronous and asynchronous evolved automata are studied under the presence of random noise of two kinds and it is shown that asynchronous cellular automata implicitly offer superior fault tolerance

asynchronous cellular automata
cellular automata
fault tolerance
discrete dynamical systems
random noise
synchronous automata


Estimation of the Poisson stream intensity in a multilinear queue with an exponential job queue decay

Abstract: Times the busy queue periods start are found for a multilinear queue with an exponential job queue decay and uniform resource allocation to individual servers. The stream intensity and the average job are estimated from observations of the times the queue busy periods start

Poisson stream intensity
multilinear queue
exponential job queue decay
busy queue periods start
uniform resource allocation
stream intensity
individual servers


Surface micromachined paraffin-actuated microvalve

Abstract: Normally-open microvalves have been fabricated and tested which use a paraffin microactuator as the active element. The entire structure with nominal dimension of phi 600 mu m * 30 mu m is batch-fabricated by surface micromachining the actuator and channel materials on top of a single substrate. Gas flow rates in the 0.01-0.1 sccm range have been measured for several devices with actuation powers ranging from 50 to 150 mW on glass substrates. Leak rates as low as 500 mu sccm have been measured. The normally-open blocking microvalve structure has been used to fabricate a precision flow control system of microvalves consisting of four blocking valve structures. The control valve is designed to operate over a 0.01-5.0 sccm flow range at a differential pressure of 800 torr. Flow rates ranging from 0.02 to 4.996 sccm have been measured. Leak rates as low as 3.2 msccm for the four valve system have been measured

surface micromachined microvalve
normally-open microvalves
paraffin microactuator
active element
channel materials
gas flow rates
actuation powers
leak rates
blocking valve structures
differential pressure
flow rates
600 micron
30 micron
50 to 150 mW
800 torr


Fuzzy systems with overlapping Gaussian concepts: Approximation properties in Sobolev norms

Abstract: In this paper the approximating capabilities of fuzzy systems with overlapping Gaussian concepts are considered. The target function is assumed to be sampled either on a regular gird or according to a uniform probability density. By exploiting a connection with Radial Basis Functions approximators, a new method for the computation of the system coefficients is provided, showing that it guarantees uniform approximation of the derivatives of the target function

fuzzy systems
overlapping Gaussian concepts
radial basis functions
learning
fuzzy system models
reproducing kernel Hilbert spaces


Conditions for the local manipulation of Gaussian states

Abstract: We present a general necessary and sufficient criterion for the possibility of a state transformation from one mixed Gaussian state to another of a bipartite continuous-variable system with two modes. The class of operations that will be considered is the set of local Gaussian completely positive trace-preserving maps

local manipulation
Gaussian states
state transformation
bipartite continuous-variable system
trace-preserving maps
quantum information theory


Deterministic single-photon source for distributed quantum networking

Abstract: A sequence of single photons is emitted on demand from a single three-level atom strongly coupled to a high-finesse optical cavity. The photons are generated by an adiabatically driven stimulated Raman transition between two atomic ground states, with the vacuum field of the cavity stimulating one branch of the transition, and laser pulses deterministically driving the other branch. This process is unitary and therefore intrinsically reversible, which is essential for quantum communication and networking, and the photons should be appropriate for all-optical quantum information processing


Self-testing chips take a load off ATE

Abstract: Looks at how chipmakers get more life out of automatic test equipment by embedding innovative circuits in silicon

embedded deterministic testing technique


Design, analysis and testing of some parallel two-step W-methods for stiff systems

Abstract: Parallel two-step W-methods are linearly-implicit integration methods where the s stage values can be computed in parallel. We construct methods of stage order q = s and order p = s with favourable stability properties. Generalizations for the concepts of A- and L-stability are proposed and conditions for stiff accuracy are given. Numerical comparisons on a shared memory computer show the efficiency of the methods, especially in combination with Krylov-techniques for large stiff systems

parallel two-step W-methods
large stiff systems
linearly-implicit integration methods
stage order
stability
shared memory computer
differential equations
convergence analysis
Krylov-techniques


A case for end system multicast

Abstract: The conventional wisdom has been that Internet protocol (IP) is the natural protocol layer for implementing multicast related functionality. However, more than a decade after its initial proposal, IP multicast is still plagued with concerns pertaining to scalability, network management, deployment, and support for higher layer functionality such as error, flow, and congestion control. We explore an alternative architecture that we term end system multicast, where end systems implement all multicast related functionality including membership management and packet replication. This shifting of multicast support from routers to end systems has the potential to address most problems associated with IP multicast. However, the key concern is the performance penalty associated with such a model. In particular, end system multicast introduces duplicate packets on physical links and incurs larger end-to-end delays than IP multicast. We study these performance concerns in the context of the Narada protocol. In Narada, end systems self-organize into an overlay structure using a fully distributed protocol. Further, end systems attempt to optimize the efficiency of the overlay by adapting to network dynamics and by considering application level performance. We present details of Narada and evaluate it using both simulation and Internet experiments. Our results indicate that the performance penalties are low both from the application and the network perspectives. We believe the potential benefits of transferring multicast functionality from end systems to routers significantly outweigh the performance penalty incurred

end system multicast
Internet protocol
protocol layer
IP multicast
network management
network scalability
higher layer functionality
congestion control
membership management
packet replication
network routers
end-to-end delays
Narada protocol
overlay structure
distributed protocol
network dynamics
application level performance
simulation
Internet experiments
performance penalties
self-organizing protocol

P P P P P R P P P P R P P P P P P P P P R


Estimation of trifocal tensor using GMM

Abstract: A novel estimation of a trifocal tensor based on the Gaussian mixture model (GMM) is presented. The mixture model is built assuming that the residuals of inliers and outliers belong to different Gaussian distributions. The Bayesian rule is then employed to detect the inliers for re-estimation. Experiments show that the presented method is more precise and relatively unaffected by outliers

trifocal tensor estimation
GMM
Gaussian mixture model
Gaussian distributions
Bayesian rule
inliers
outliers
motion analysis
image data
image analysis


Human factors research on data modeling: a review of prior research, an extended framework and future research directions

Abstract: This study reviews and synthesizes human factors research on conceptual data modeling. In addition to analyzing the variables used in earlier studies and summarizing the results of this stream of research, we propose a new framework to help with future efforts in this area. The study finds that prior research has focused on issues that are relevant when conceptual models are used for communication between systems analysts and developers (Analyst Developer models) whereas the issues important for models that are used to facilitate communication between analysts and users (User-Analyst models) have received little attention and, hence, require a significantly stronger role in future research. In addition, we emphasize the importance of building a strong theoretical foundation and using it to guide future empirical work in this area

human factors
conceptual data modeling
future efforts
Analyst Developer models
User-Analyst models
database


VPP Fortran and the design of HPF/JA extensions

Abstract: VPP Fortran is a data parallel language that has been designed for the VPP series of supercomputers. In addition to pure data parallelism, it contains certain low-level features that were designed to extract high performance from user programs. A comparison of VPP Fortran and High-Performance Fortran (HPF) 2.0 shows that these low-level features are not available in HPF 2.0. The features include asynchronous interprocessor communication, explicit shadow, and the LOCAL directive. They were shown in VPP Fortran to be very useful in handling real-world applications, and they have been included in the HPF/JA extensions. They are described in the paper. The HPF/JA Language Specification Version 1.0 is an extension of HPF 2.0 to achieve practical performance for real-world applications and is a result of collaboration in the Japan Association for HPF (JAHPF). Some practical programming and tuning procedures with the HPF/JA Language Specification are described, using the NAS Parallel Benchmark BT as an example


Packet spacing: an enabling mechanism for delivering multimedia content in computational grids

Abstract: Streaming multimedia with UDP has become increasingly popular over distributed systems like the Internet. Scientific applications that stream multimedia include remote computational steering of visualization data and video-on-demand teleconferencing over the Access Grid. However, UDP does not possess a self-regulating, congestion-control mechanism; and most best-effort traffic is served by congestion-controlled TCP. Consequently, UDP steals bandwidth from TCP such that TCP flows starve for network resources. With the volume of Internet traffic continuing to increase, the perpetuation of UDP-based streaming will cause the Internet to collapse as it did in the mid-1980's due to the use of non-congestion-controlled TCP. To address this problem, we introduce the counter-intuitive notion of inter-packet spacing with control feedback to enable UDP-based applications to perform well in the next-generation Internet and computational grids. When compared with traditional UDP-based streaming, we illustrate that our approach can reduce packet loss over 50% without adversely affecting delivered throughput

streaming multimedia
UDP
distributed systems
Internet
remote computational steering
visualization data
inter-packet spacing
UDP-based streaming
network protocol
transport protocols


SIA shelves T+1 decision till 2004

Abstract: The Securities Industry Association has decided that a move to T+1 is more than the industry can handle right now. STP, however, will remain a focus

Securities Industry Association
straight-through-processing
T+1


Application of traditional system design techniques to Web site design

Abstract: After several decades of computer program construction there emerged a set of principles that provided guidance to produce more manageable programs. With the emergence of the plethora of Internet web sites one wonders if similar guidelines are followed in their construction. Since this is a new technology no apparent universally accepted methods have emerged to guide the designer in Web site construction. This paper reviews the traditional principles of structured programming and the preferred characteristics of Web sites. Finally a mapping of how the traditional guidelines may be applied to Web site construction is presented. The application of the traditional principles of structured programming to the design of a Web site can provide a more usable site for the visitors to the site. The additional benefit of using these time-honored techniques is the creation of a Web site that will be easier to maintain by the development staff

Internet Web site design
system design techniques
structured programming


Bistability of harmonically forced relaxation oscillations

Abstract: Relaxation oscillations appear in processes which involve transitions between two states characterized by fast and slow time scales. When a relaxation oscillator is coupled to an external periodic force its entrainment by the force results in a response which can include multiple periodicities and bistability. The prototype of these behaviors is the harmonically driven van der Pol equation which displays regions in the parameter space of the driving force amplitude where stable orbits of periods 2n+or-1 coexist, flanked by regions of periods 2n+1 and 2n-1. The parameter regions of such bistable orbits are derived analytically for the closely related harmonically driven Stoker-Haag piecewise discontinuous equation. The results are valid over most of the control parameter space of the system. Also considered are the reasons for the more complicated dynamics featuring regions of high multiple periodicity which appear like noise between ordered periodic regions. Since this system mimics in detail the less analytically tractable forced van der Pol equation, the results suggest extensions to situations where forced relaxation oscillations are a component of the operating mechanisms


A three-source model for the calculation of head scatter factors

Abstract: Accurate determination of the head scatter factor S/sub c/ is an important issue, especially for intensity modulated radiation therapy, where the segmented fields are often very irregular and much less than the collimator jaw settings. In this work, we report an S/sub c/ calculation algorithm for symmetric, asymmetric, and irregular open fields shaped by the tertiary collimator (a multileaf collimator or blocks) at different source-to-chamber distance. The algorithm was based on a three-source model, in which the photon radiation to the point of calculation was treated as if it originated from three effective sources: one source for the primary photons from the target and two extra-focal photon sources for the scattered photons from the primary collimator and the flattening filter, respectively. The field mapping method proposed by Kim et al. [Phys. Med. Biol. 43, 1593-1604 (1998)] was extended to two extra-focal source planes and the scatter contributions were integrated over the projected areas (determined by the detector's eye view) in the three source planes considering the source intensity distributions. The algorithm was implemented using Microsoft Visual C/C++ in the MS Windows environment. The only input data required were head scatter factors for symmetric square fields, which are normally acquired during machine commissioning. A large number of different fields were used to evaluate the algorithm and the results were compared with measurements. We found that most of the calculated S/sub c/'s agreed with the measured values to within 0.4%. The algorithm can also be easily applied to deal with irregular fields shaped by a multileaf collimator that replaces the upper or lower collimator jaws

three-source model
head scatter factors
intensity modulated radiation therapy
segmented fields
collimator jaw settings
calculation algorithm
symmetric
fields
asymmetric
fields
irregular open fields
tertiary collimator
multileaf collimator
blocks
source-to-chamber distance
photon radiation
target
extra-focal photon sources
scattered photons
primary collimator
flattening filter
field mapping method
extra-focal source planes
source intensity distributions
MS Windows environment
input data
symmetric square fields
machine commissioning
upper collimator jaws
lower collimator jaws

P P P P P P P P P P P P P P P P P P P P P P P P P P P P R P


Virtual projects at Halden [Reactor Project]

Abstract: The Halden man-machine systems (MMS) programme for 2002 is intended to address issues related to human factors, control room design, computer-based support system areas and system safety and reliability. The Halden MMS programme is intended to address extensive experimental work in the human factors, control room design and computer-based support system areas. The work is based on experiments and demonstrations carried out in the experimental facility HAMMLAB. Pilot-versions of several operator aids are adopted and integrated to the HAMMLAB simulators and demonstrated in a full dynamic setting. The Halden virtual reality laboratory has recently become an integral and important part of the programme

Halden Reactor Project
man-machine systems programme
human factors
computer-based support system
safety
reliability
virtual reality
control room design


Mathematical model of functioning of an insurance company with allowance for advertising expenses

Abstract: A mathematical model of the functioning of an insurance company with allowance for advertising expenses is suggested. The basic characteristics of the capital of the company and the advertising efficiency are examined in the case in which the advertising expenses are proportional to the capital

insurance company functioning
advertising expenses allowance
capital
mathematical model


Valuing corporate debt: the effect of cross-holdings of stock and debt

Abstract: We have developed a simple approach to valuing risky corporate debt when corporations own securities issued by other corporations. We assume that corporate debt can be valued as an option on corporate business asset value, and derive payoff functions when there exist cross-holdings of stock or debt between two firms. Next we show that payoff functions with multiple cross-holdings can be solved by the contraction principle. The payoff functions which we derive provide a number of insights about the risk structure of company cross-holdings. First, the Modigliani-Miller theorem can obtain when there exist cross-holdings between firms. Second, by establishing cross-shareholdings each of stock holders distributes a part of its payoff values to the bond holder of the other's firm, so that both firms can decrease credit risks by cross-shareholdings. In the numerical examples, we show that the correlation in firms can be a critical condition for reducing credit risk by cross-holdings of stock using Monte Carlo simulation. Moreover, we show we can calculate the default spread easily when complicated cross-holdings exist, and find which shares are beneficial or disadvantageous

risky corporate debt valuation
stock holdings
debt holdings
securities
option
corporate business asset value
payoff functions
multiple cross-holdings
Modigliani-Miller theorem
cross-shareholdings
bond holder
credit risks
correlation
Monte Carlo simulation


Digital rights (and wrongs)

Abstract: Attempting to grasp the many conflicts and proposed safeguards for intellectual property is extremely difficult. Legal, political, economic, and cultural issues-both domestic and international-loom large, almost dwarfing the daunting technological challenges. Solutions devised by courts and legislatures and regulatory agencies are always late out of the blocks and fall ever farther behind. Recently proposed legislation only illustrates the depth and complexity of the problem

intellectual property
cultural issues
economic issues
political issues
legal issues


Improving the frequency stability of microwave oscillators by utilizing the dual-mode sapphire-loaded cavity resonator

Abstract: The design and experimental testing of a novel control circuit to stabilize the temperature of a sapphire-loaded cavity whispering gallery resonator-oscillator and improve its medium-term frequency stability is presented. Finite-element software was used to predict frequencies and quality factors of WGE/sub 7,0,0/ and the WGH/sub 9,0,0/ modes near 9 GHz, and separated in frequency by approximately 80 MHz. Calculations show that the novel temperature control circuits from the difference frequency can result in a frequency stability of better than one part in 10/sup 13/ at 270 K. Also, we present details on the best way to couple orthogonally to two modes of similar frequency but different polarization


A robust H/sub infinity / control approach for induction motors

Abstract: This paper deals with the robustness and stability of an induction motor control structure against internal and external disturbances. In the proposed control scheme, we have used an H/sub infinity / controller with field orientation and input-output linearization to achieve the above-specified features. Simulation results are included to illustrate the control approach performances

robust H/sub infinity / control
induction motors control
robustness
stability
internal disturbances
external disturbances
field orientation
input-output linearization


A new approach to the d-MC problem

Abstract: Many real-world systems are multi-state systems composed of multi-state components in which the reliability can be computed in terms of the lower bound points of level d, called d-Mincuts (d-MCs). Such systems (electric power, transportation, etc.) may be regarded as flow networks whose arcs have independent, discrete, limited and multi-valued random capacities. In this paper, all MCs are assumed to be known in advance, and the authors focused on how to verify each d-MC candidate before using d-MCs to calculate the network reliability. The proposed algorithm is more efficient than existing algorithms. The algorithm runs in O(p sigma mn) time, a significant improvement over the previous O(p sigma m/sup 2/) time bounds based on max-flow/min-cut, where p and or are the number of MCs and d-MC candidates, respectively. It is simple, intuitive and uses no complex data structures. An example is given to show how all d-MC candidates are found and verified by the proposed algorithm. Then the reliability of this example is computed

d-MC problem
multi-state systems
multi-state components
reliability computation
d-Mincuts
flow networks
failure analysis algorithm
time bounds
max-flow/min-cut


Hybrid broadcast for the video-on-demand service

Abstract: Multicast offers an efficient means of distributing video contents/programs to multiple clients by batching their requests and then having them share a server's video stream. Batching customers' requests is either client-initiated or server-initiated. Most advanced client-initiated video multicasts are implemented by patching. Periodic broadcast, a typical server-initiated approach, can be entirety-based or segment-based. This paper focuses on the performance of the VoD service for popular videos. First, we analyze the limitation of conventional patching when the customer request rate is high. Then, by combining the advantages of each of the two broadcast schemes, we propose a hybrid broadcast scheme for popular videos, which not only lowers the service latency but also improves clients' interactivity by using an active buffering technique. This is shown to be a good compromise for both lowering service latency and improving the VCR-like interactivity

quality-of-service
interactivity
scheduling
video-on-demand
multicast
conventional patching
customer request rate
hybrid broadcast scheme


Impossible choice [web hosting service provider]

Abstract: Selecting a telecoms and web hosting service provider has become a high-stakes game of chance

web hosting service provider
IT managers
selection
customer service


Using k-nearest-neighbor classification in the leaves of a tree

Abstract: We construct a hybrid (composite) classifier by combining two classifiers in common use - classification trees and k-nearest-neighbor (k-NN). In our scheme we divide the feature space up by a classification tree, and then classify test set items using the k-NN rule just among those training items in the same leaf as the test item. This reduces somewhat the computational load associated with k-NN, and it produces a classification rule that performs better than either trees or the usual k-NN in a number of well-known data sets

k-nearest-neighbor classification
tree leaves
hybrid composite classifier
classification trees
feature space division
computational load
data sets
k-NN rule


An intelligent information gathering method for dynamic information mediators

Abstract: The Internet is spreading into our society rapidly and is becoming one of the information infrastructures that are indispensable for our daily life. In particular, the WWW is widely used for various purposes such as sharing personal information, academic research, business work, and electronic commerce, and the amount of available information is increasing rapidly. We usually utilize information sources on the Internet as individual stand-alone sources, but if we can integrate them, we can add more value to each of them. Hence, information mediators, which integrate information distributed on the Internet, are drawing attention. In this paper, under the assumption that the information sources to be integrated are updated frequently and asynchronously, we propose an information gathering method that constructs an answer to a query from a user, accessing information sources to be integrated properly within an allowable time period. The proposed method considers the reliability of data in the cache and the quality of answer in order to efficiently access information sources and to provide appropriate answers to the user. As evaluation, we show the effectiveness of the proposed method by using an artificial information integration problem, in which some parameters can be modified, and a real-world flight information service compared with a conventional FIFO information gathering method


Formalising optimal feature weight setting in case based diagnosis as linear programming problems

Abstract: Many approaches to case based reasoning (CBR) exploit feature weight setting algorithms to reduce the sensitivity to distance functions. We demonstrate that optimal feature weight setting in a special kind of CBR problems can be formalised as linear programming problems. Therefore, the optimal weight settings can be calculated in polynomial time instead of searching in exponential weight space using heuristics to get sub-optimal settings. We also demonstrate that our approach can be used to solve classification problems

optimal feature weight setting
case based diagnosis
linear programming
case based reasoning
distance functions
polynomial time
searching
exponential weight space
classification
heuristics


Schema evolution in data warehouses

Abstract: We address the issues related to the evolution and maintenance of data warehousing systems, when underlying data sources change their schema capabilities. These changes can invalidate views at the data warehousing system. We present an approach for dynamically adapting views according to schema changes arising on source relations. This type of maintenance concerns both the schema and the data of the data warehouse. The main issue is to avoid the view recomputation from scratch especially when views are defined from multiple sources. The data of the data warehouse is used primarily in organizational decision-making and may be strategic. Therefore, the schema of the data warehouse can evolve for modeling new requirements resulting from analysis or data-mining processing. Our approach provides means to support schema evolution of the data warehouse independently of the data sources

schema evolution
data warehouses
system maintenance
containment
data sources
source relations
structural view maintenance
view adaptation
SQL query
organizational decision-making
data analysis


Gender benders [women in computing profession]

Abstract: As a minority in the upper levels of the computing profession, women are sometimes mistreated through ignorance or malice. Some women have learned to respond with wit and panache


Active pitch control in larger scale fixed speed horizontal axis wind turbine systems. I. linear controller design

Abstract: This paper reviews and addresses the principles of linear controller design of the fixed speed wind turbine system in above rated wind speed, using pitch angle control of the blades and applying modern control theory. First, the nonlinear equations of the system are built in under some reasonable suppositions. Then, the nonlinear equations are linearised at set operating point and digital simulation results are shown in this paper. Finally, a linear quadratic optimal feedback controller is designed and the dynamics of the closed circle system are simulated with digital calculation. The advantages and disadvantages of the assumptions and design method are also discussed. Because of the inherent characteristics of the linear system control theory, the performance of the linear controller is not sufficient for operating wind turbines, as is discussed


Web content extraction. A WhizBang! approach

Abstract: The extraction technology that Whizbang uses consists of a unique approach to scouring the Web for current, very specific forms of information. FlipDog, for example, checks company Web sites for hyperlinks to pages that list job opportunities. It then crawls to the deeper page and, using the WhizBang! Extraction Framework, extracts the key elements of the postings, such as job title, name of employer, job category, and job function. Click on a job and you are transferred to the company Web site to view the job description as it appears there

Web content extraction
FlipDog
job description
job-hunting site
company Web sites
WhizBang! Extraction Framework


Implementation of DIMSIMs for stiff differential systems

Abstract: Some issues related to the implementation of diagonally implicit multistage integration methods for stiff differential systems are discussed. They include reliable estimation of the local discretization error, construction of continuous interpolants, solution of nonlinear systems of equations by simplified Newton iterations, choice of initial stepsize and order, and step and order changing strategy. Numerical results are presented which indicate that an experimental Matlab code based on type 2 methods of order one, two and three outperforms ode15s code from Matlab ODE suite on problems whose Jacobian has eigenvalues which are close to the imaginary axis


Look who's talking [voice recognition]

Abstract: Voice recognition could be the answer to the problem of financial fraud, but in the world of biometric technology, money talks

voice recognition
financial fraud
biometric
cost


Quadratic Newton iteration for systems with multiplicity

Abstract: Newton's iterator is one of the most popular components of polynomial equation system solvers, either from the numeric or symbolic point of view. This iterator usually handles smooth situations only (when the Jacobian matrix associated to the system is invertible). This is often a restrictive factor. Generalizing Newton's iterator is still an open problem: How to design an efficient iterator with a quadratic convergence even in degenerate cases? We propose an answer for an m-adic topology when the ideal m can be chosen generic enough: compared to a smooth case we prove quadratic convergence with a small overhead that grows with the square of the multiplicity of the root

quadratic Newton iteration
systems with multiplicity
Newton's iterator
polynomial equation system solvers
Jacobian matrix
quadratic convergence
m-adic topology


When the unexpected happens [disaster planning in banks]

Abstract: A business disruption can be as simple as a power failure or as complex as a terrorist attack. Regardless, you will need to have a plan to minimize interruptions to both your bank and your customers. Marketers have a role in this readiness process

disaster planning
banks
planning
recovery
public relations
emergency management


Selective representing and world-making

Abstract: We discuss the thesis of selective representing-the idea that the contents of the mental representations had by organisms are highly constrained by the biological niches within which the organisms evolved. While such a thesis has been defended by several authors elsewhere, our primary concern here is to take up the issue of the compatibility of selective representing and realism. We hope to show three things. First, that the notion of selective representing is fully consistent with the realist idea of a mind-independent world. Second, that not only are these two consistent, but that the latter (the realist conception of a mind-independent world) provides the most powerful perspective from which to motivate and understand the differing perceptual and cognitive profiles themselves. Third, that the (genuine and important) sense in which organism and environment may together constitute an integrated system of scientific interest poses no additional threat to the realist conception

world-making
selective representing
mental representations
organisms
realism
mind-independent world
cognitive profiles


Dynamics and control of initialized fractional-order systems

Abstract: Due to the importance of historical effects in fractional-order systems, this paper presents a general fractional-order system and control theory that includes the time-varying initialization response. Previous studies have not properly accounted for these historical effects. The initialization response, along with the forced response, for fractional-order systems is determined. The scalar fractional-order impulse response is determined, and is a generalization of the exponential function. Stability properties of fractional-order systems are presented in the complex w-plane, which is a transformation of the s-plane. Time responses are discussed with respect to pole positions in the complex w-plane and frequency response behavior is included. A fractional-order vector space representation, which is a generalization of the state space concept, is presented including the initialization response. Control methods for vector representations of initialized fractional-order systems are shown. Finally, the fractional-order differintegral is generalized to continuous order-distributions which have the possibility of including all fractional orders in a transfer function

initialized fractional-order systems
dynamics
control
initialization response
forced response
impulse response
exponential function
vector space representation
state space concept
fractional-order differintegral
transfer function


Computing 2002: democracy, education, and the future

Abstract: Computer scientists, computer engineers, information technologists, and their collective products have grown and changed in quantity, quality, and nature. In the first decade of this new century, it should become apparent to everyone that the computing and information fields, broadly defined, will have a profound impact on every element of every person's life. The author considers how women and girls of the world have been neither educated for computing nor served by computing. Globally, women's participation in computer science grew for a while, then dropped precipitously. Computing, science, engineering, and society will suffer if this decline continues, because women have different perspectives on technology, what it is important for, how it should be built, which projects should be funded, and so on. To create a positive future, to assure that women equally influence the future, computing education must change

computer science education
gender issues
future
women
girls
society
democracy


Reply to Carreira-Perpinan and Goodhill [mathematics in biology]

Abstract: In a paper by Carreira-Perpinan and Goodhill (see ibid., vol.14, no.7, p.1545-60, 2002) the authors apply mathematical arguments to biology. Swindale et al. think it is inappropriate to apply the standards of proof required in mathematics to the acceptance or rejection of scientific hypotheses. To give some examples, showing that data are well described by a linear model does not rule out an infinity of other possible models that might give better descriptions of the data. Proving in a mathematical sense that the linear model was correct would require ruling out all other possible models, a hopeless task. Similarly, to demonstrate that two DNA samples come from the same individual, it is sufficient to show a match between only a few regions of the genome, even though there remains a very large number of additional comparisons that could be done, any one of which might potentially disprove the match. This is unacceptable in mathematics, but in the real world, it is a perfectly reasonable basis for belief

mathematical arguments
biology
scientific hypotheses
linear model
DNA
genome
hypothesis testing
cortical maps
neural nets


Automatic multilevel thresholding for image segmentation by the growing time adaptive self-organizing map

Abstract: In this paper, a Growing TASOM (Time Adaptive Self-Organizing Map) network called "GTASOM" along with a peak finding process is proposed for automatic multilevel thresholding. The proposed GTASOM is tested for image segmentation. Experimental results demonstrate that the GTASOM is a reliable and accurate tool for image segmentation and its results outperform other thresholding methods


Efficient feasibility testing for dial-a-ride problems

Abstract: Dial-a-ride systems involve dispatching a vehicle to satisfy demands from a set of customers who call a vehicle-operating agency requesting that an item tie picked up from a specific location and delivered to a specific destination. Dial-a-ride problems differ from other routing and scheduling problems, in that they typically involve service-related constraints. It is common to have maximum wait time constraints and maximum ride time constraints. In the presence of maximum wait time and maximum ride time restrictions, it is not clear how to efficiently determine, given a sequence of pickups and deliveries, whether a feasible schedule exists. We demonstrate that this, in fact, can be done in linear time

feasibility testing
dial-a-ride problems
dispatching
vehicle-operating agency
routing
scheduling
service-related constraints
maximum wait time constraints
maximum ride time constraints