ppxscal/embedding_network huggingface dataset:
Generalized multiple importance sampling for Monte-Carlo global illumination
Authors: Ferenc Csonka, László Szirmay-Kalos, György Antal
Venue: Machine Graphics Vision International Journal (2002)

The global illumination or transport problems can be considered as a sequence of integrals, while their Monte-Carlo solutions - as different sampling techniques. Multiple importance sampling takes advantage of different sampling strategies, and combines the results obtained with them to establish a quasi-optimal sampling for Monte-Carlo quadratures. This offers a combination of totally different global illumination algorithms which preserves their strengths. However, implementation of this general concept poses two problems. The solution of the global illumination problem does not contain a single integral, but a sequence of integrals that are approximated simultaneously. One objective of this paper is to generalize the fundamental theory of multiple importance sampling to sequences of integrals. The cost of the computation and the contribution of a single integral to the final result vary. On the other hand, different methods compute a sample with different computational burdens, which should also be taken into account. This paper attacks this problem and introduces the concept of computational cost in multiple importance sampling. The theoretical results are used to combine bi-directional path tracing and ray-bundle based stochastic iteration. We conclude that the combined method preserves the high initial speed of stochastic iteration, but can also accurately compute the specular light paths through bi-directional path tracing.
Research Report: Better Theory Through Measurement-Developing a Scale to Capture Consensus on Appropriation
Authors: Wm. David Salisbury, Wynne W. Chin, Abhijit Gopal, Peter R. Newsted
Venue: Information Systems Research (2002)

Proper measurement is critical to the advancement of theory (Blalock 1979). Adaptive Structuration Theory (AST) is rapidly becoming an important theoretical paradigm for comprehending the impacts of advanced information technologies (DeSanctis and Poole 1994). Intended as a complement to the faithfulness of appropriation scale developed by Chin et al. (1997), this research note describes the development of an instrument to capture the AST construct of consensus on appropriation. Consensus on appropriation (COA) is the extent to which group participants perceive that they have agreed on how to adopt and use a technology. While consensus on appropriation is an important component of AST, no scale is currently available to capture this construct. This research note develops a COA instrument in the context of electronic meeting systems use. Initial item development, statistical analyses, and validity assessment (convergent, discriminant, and nomological) are described here in detail. The contribution of this effort is twofold: First, a scale is provided for an important construct from AST. Second, this report serves as an example of rigorous scale development using structural equation modeling. Employing rigorous procedures in the development of instruments to capture AST constructs is critical if the sound theoretical base provided by AST is to be fully exploited in understanding phenomena related to the use of advanced information technologies.
Performance analysis and optimal control of the Geo/Geo/c queue
Authors: J. R. Artalejo, O. Hernández-Lerma
Venue: Performance Evaluation (2003)

Discrete-time multiserver queues have been used for many years to investigate the behavior of communication and computer systems in which time is slotted. In this paper, we consider the discrete-time Geo/Geo/c queue. We first develop an efficient recursive procedure to obtain the steady-state probabilities and prove the convergence to the continuous-time counterpart. We also deal with the infinite-horizon discounted cost criterion for the arrival and service rate control problems. Optimal stationary policies and Value functions are determined. This allows us to compare both control problems.
Reiser4, Part II: designing trees that cache well
Authors: Hans Reiser
Venue: Linux Journal (2003)

Discover the next step in the evolution of an innovative filesystem for Linux.
DSS for rescheduling of railway services under unplanned events
Authors: B. Adenso-Díaz, J. Tuya, M. J. Suárez-Cabal, M. Goitia-Fuertes
Venue: Decision making support systems: achievements, trends and challenges for (2002)

In the daily activity of railway transport, the need to make decisions when faced with unforeseen incidents is a common event. Quality of service my be affected by decisions that are made by delays or cancellations. In this multiobjective scenario, there is a need to combine affecting the majority of passengers as little as possible with the minimization of costs. Therefore it is necessary to design planning algorithms taking into account factors such as the availability of engines and the quality of service. This chapter presents the design and implementation experience of a practical case developed for the Spanish Railway Company. With this tool, a DSS was put into service that guides the person in charge as to which measures to adopt with respect to the events that have arisen. The information employed is obtained by means of heuristic search algorithms based on backtracking for the exploration of the solutions space.
On the problem of performing exact partial abductive inference in Bayesian belief networks using junction trees
Authors: Luis M. de Campos, José A. Gámez, Serafín Moral
Venue: Technologies for constructing intelligent systems: tools (2002)

Partial abductive inference in Bayesian belief networks has been usually expressed as an extension of total abductive inference (abduction over all the variables in the network). In this paper we study the transformation of the partial problem in a total one, analyzing and trying to improve the method previously appeared in the literature. We also outline an alternative approach, and compare both methods by means of experimentation. The experimental results reveal that the problem of partial abductive inference is difficult to solve by exact computation.
Fluid-structure interaction: applications in nonlinear aeroelasticity
Authors: B. H. K. Lee
Venue: Scientific computing and applications (2001)

Nonlinear aeroelasticity is discussed firstly from the signal processing point of view. The method of phase-space reconstruction is described and an example using wind tunnel data of an unmanned flight vehicle is presented to demonstrate the occurrence of limit-cycle oscillations. Two-dimensional numerical simulation of an airfoil containing a freeplay structural nonlinearity is carried out to show the bifurcation process that eventually leads to chaotic motion.
Power series expansions for spheroidal wave functions with small arguments
Authors: Gerassimos C. Kokkorakis, John A. Roumeliotis
Venue: Journal of Computational and Applied Mathematics (2002)

Power series expansions for the angular spheroidal wave functions of the first kind Smn(c,η), with small arguments c, are derived for general integer values of m and n. The various evaluated expansion coefficients can also be used in the calculation of the corresponding angular functions of the second kind, as well as for the radial functions of any kind. Only the prolate functions are considered explicitly, but corresponding formulas for the oblate ones are obtained immediately.
Computation of Periodic Solution Bifurcations in ODEs Using Bordered Systems
Authors: E. J. Doedel, W. Govaerts, Yu. A. Kuznetsov
Venue: SIAM Journal on Numerical Analysis (2003)

We consider numerical methods for the computation and continuation of the three generic secondary periodic solution bifurcations in autonomous ODEs, namely the fold, the period-doubling (or flip) bifurcation, and the torus (or Neimark--Sacker) bifurcation. In the fold and flip cases we append one scalar equation to the standard periodic BVP that defines the periodic solution; in the torus case four scalar equations are appended. Evaluation of these scalar equations and their derivatives requires the solution of linear BVPs, whose sparsity structure (after discretization) is identical to that of the linearization of the periodic BVP. Therefore the calculations can be done using existing numerical linear algebra techniques, such as those implemented in the software AUTO and COLSYS.
Adopting a Plurality Vote Perspective
Authors: Donald G. Saari
Venue: Mathematics of Operations Research (2002)

For three-alternative positional voting and decision methods, it is shown how to decompose the profiles and data sets in a manner which identifies all possible conflict relative to a specified procedure. This approach is illustrated with the plurality vote by characterizing all possible profiles which cause all possible conflicts between the plurality and other pairwise and/or positional procedures. The approach then is used to cast doubt on an often-cited plurality vote property.
Java visualization using BlueJ
Authors: Frances Bailie, Glenn Blank, Keitha Murray, Rathika Rajaravivarma
Venue: Journal of Computing Sciences in Colleges (2003)

The BlueJ environment was developed by a joint research group at Monash University, Melbourne, Australia, and the Mærsk Institute at the University of Southern Denmark specifically for introducing object oriented programming to beginners. BlueJ provides an interactive environment for the teaching of Java that emphasizes visualization and experimentation. Panelists will demonstrate BlueJ and describe their experiences teaching Java using BlueJ.
Modeling nonlinear relationships between extended-memory variables
Authors: C. W. J. Granger
Venue: Essays in econometrics: Spectral analysis, seasonality, nonlinearity, methodology, and forecasting (2001)

Many economic variables have a persistence property which may be called extended memory and the relationship between variables may well be nonlinear. This pair of properties allow for many more types of model misspecification than encountered with stationary or short-memory variables and linear relationships, and misspecifications lead to greater modeling difficulties. Examples are given using the idea of a model being balanced.Alternative definitions of extended memory are considered and a definition based on the properties of optimum forecasts is selected for later use. An important but not necessarily pervasive class of processes are those that are extended-memory but whose changes are short-memory. For this case, called I(1), standard cointegration ideas will apply.Tests of linearity are discussed in both the I(1) case, where a possible group of tests is easily found, and more generally. Similarly, methods of building nonlinear models based on familiar techniques, such as neural networks and projection pursuit, are briefly considered for I(1) and the more general case. A number of areas requiring further work in this new area are emphasized.
Models and Algorithms for Single-Depot Vehicle Scheduling
Authors: Richard Freling, Albert P. M. Wagelmans, José M. Pinto Paixão
Venue: Transportation Science (2001)

Vehicle scheduling is the process of assigning vehicles to a set of predetermined trips with fixed starting and ending times, while minimizing capital and operating costs. This paper considers modeling, algorithmic, and computational aspects of the polynomially solvable case in which there is a single depot and vehicles are identical. A quasiassignment formulation is reviewed and an alternative asymmetric assignment formulation is given. The main contributions of the paper are a new two-phase approach which is valid in the case of a special cost structure, an auction algorithm for the quasiassignment problem, a core-oriented approach, and an extensive computational study. New algorithms are compared with the most successful algorithms for the vehicle-scheduling problem, using both randomly generated and real-life data. The new algorithms show a significant performance improvement with respect to computation time. Such improvement can, for example, be very important when this particular vehicle-scheduling problem appears as a subproblem in more complex vehicle- and crew-scheduling problems.
Extension on common cycle lot-size scheduling for multi-product, multi-stage arborescent flow-shop environment
Authors: S. M. T. Fatemi Ghomi, S. A. Torabi
Venue: Iranian Journal of Science and Technology (2001)

This paper studies the problem of common cycle lot-size scheduling for a multiproduct, multi-stage arborescent flow-shop environment under deterministic and stationary conditions, assuming a fixed sequence maintaining across all processing stages. The considered costs for modelling include set-up costs, carrying costs of finished inventory and carrying costs of in-process inventories. The policy of production scheduling is the use of an identical and common cycle for all stages, and the lot size of every product is computed based on its forecasted demand over the production cycle time.The aim of this paper is to present the solution methods for the problem and to determine simultaneous production cycle time and production schedule with minimum cost. For this purpose, an optimal method and a heuristic procedure are developed and applied for various examples. Computational results demonstrate that the solutions gained through the heuristic procedure are very close to the optimal solutions. In fact, it is proved that the heuristic procedure is highly efficient and can be applied for the problems of great size.
Optimal buffered routing path constructions for single and multiple clock domain systems
Authors: Soha Hassoun, Charles J. Alpert, Meera Thiagarajan
Venue: Proceedings of the 2002 IEEE/ACM international conference on Computer-aided design (2002)

Shrinking process geometries and the increasing use of IP components in SoC designs give rise to new problems in routing and buffer insertion. A particular concern is that cross-chip routing will require multiple clock cycles. Another is the integration of independently clocked components. This paper explores simultaneous routing and buffer insertion in the context of single and multiple clock domains. We present optimal and efficient polynomial algorithms that can be used to estimate communication overhead for interconnect and resource planning in single and multi-clock domain systems. Experimental results verify the correctness and practicality of our approach.
vGPRS: a mechanism for voice over GPRS
Authors: Ming-Feng Chang, Yi-Bing Lin, Ai-Chun Pang
Venue: Wireless Networks (2003)

This paper proposes vGPRS, a voice over IP (VoIP) mechanism for general packet radio service (GPRS) network. In this approach, a new network element called VoIP mobile switching center (VMSC) is introduced to replace standard GSM MSC. Both standard GSM and GPRS mobile stations can be used to receive real-time VoIP service, which need not be equipped with the VoIP (i.e., H.323) terminal capabilities. The vGPRS approach is implemented using standard H.323, GPRS, and GSM protocols. Thus, existing GPRS and H.323 network elements are not modified. Furthermore, the message flows for vGPRS registration, call origination, call release and call termination procedures are described to show the feasibility of our vGPRS system.
The freeze algorithms for concurrency control in secure real-time database systems
Authors: Chanjung Park, Seog Park
Venue: Data Knowledge Engineering (2003)

Database systems for real-time applications must satisfy timing constraints associated with transactions. Typically, a timing constraint is expressed in the form of a deadline and is represented as a priority to be used by schedulers. Recently, security has become another important issue in many real-time applications. In many systems, sensitive information is shared by multiple users with different levels of security clearance. As more advanced database systems are being used in applications that need to support timeliness while managing sensitive information, there is an urgent need to develop concurrency control (CC) algorithms in transaction management that satisfy both timing and security requirements.In this paper, we propose two CC algorithms that ensure both security and real-time requirements. The proposed algorithms are primarily based on MV locking. However, in order to satisfy timing constraints and security requirements, a new method, called the Freeze, is proposed. In addition, we show that our algorithms work correctly and they provide a higher degree of concurrency than existing MV algorithms. We present several examples to illustrate the behavior of our algorithms, along with performance comparisons with other algorithms. The simulation results show significant performance improvement of the proposed algorithms.
Rendezvous Search on the Line with Limited Resources: Maximizing the Probability of Meeting
Authors: Steve Alpern, Anatole Beck
Venue: Operations Research (1999)

Two players are placed on a line at a distance d which is drawn from a known distribution F. The players have no common notion of direction on the line, and each has a resources bound on the total distance he can travel. If F is bounded and the resources are sufficiently large, then the players can ensure a meeting. The expected time minimization problem in that case has been studied by the authors in a previous paper. Aside from that case the most the players can do is maximize the probability that they meet. This is the problem studied here, for general and speci*cdistributions. This problem generalizes that of Foley et al. (1991), where one of the players is stationary (zero resources).
Exact Evaluation of Batch-Ordering Inventory Policies in Two-Echelon Supply Chains with Periodic Review
Authors: Gérard P. Cachon
Venue: Operations Research (2001)

This paper studies a two-echelon supply chain with stochastic and discrete consumer demand, batch order quantities, periodic inventory review, and deterministic transportation times. Reorder point policies manage inventories at every location. Average inventory, backorders and fill rates are evaluated exactly for each location. Safety stock is evaluated exactly at the lower echelon and a good approximation is detailed for the upper echelon. Numerical data are presented to demonstrate the model's utility. It is found that system costs generally increase substantially if the upper echelon is restricted to carry no inventory, of if the upper echelon is required to provide a high fill rate. In many cases it is optimal to set the upper echelon's reorder point to yield near zero safety stock, yet in some cases this simple heuristic can significantly increase supply chain operating costs. Finally, policies selected under the assumption of continuous inventory review can perform poorly if implemented in an environment with periodic review.
(S, S) Continuous Review Models for Products with Fixed Lifetimes
Authors: Liming Liu, Zhaotong Lian
Venue: Operations Research (1999)

We analyze an (s, S) continuous review perishable inventory system with a general renewal demand process and instantaneous replenishments. Though continuous review systems seem more amenable to optimization analysis than do periodic review systems, the existing literature addressing this type of model is rather limited. This limitation motivated us to seek greater understanding of this important class of inventory models. Using a Markov renewal approach, we obtain closed-form solutions for the steady state probability distribution of the inventory level and system performance measures. We then construct a closed-form expected cost function. Useful analytical properties for the cost function are identified and extensive computations are conducted to examine the impact of different parameters. The numerical results illustrate the system behavior and lead to managerial insights into controlling such inventory systems.
Distributed processing of remotely sensed Landsat-TM imagery using MPI
Authors: J. A. Gallud, J. García-Consuegra, A. Martínez
Venue: Cluster Computing (2001)

One of the constraints in remotely-sensed images processing is the computational resources required. Distributed processing is applied in remote sensing in order to reduce spatial or temporal cost using the message passing paradigm. In this paper, we present a workbench developed to provide a framework to perform the distributed processing of Landsat images using a cluster of NT workstations. A set of functions and a message structure, called DIPORSI, have been designed to distribute the main algorithms employed in remote sensing. Thus, the large amount of time required by the sequential process drops when the distributed algorithm is used. Our application is based on the NT implementation (WinMPICH) of the MPI standard.
Sounding Objects
Authors: Davide Rocchesso, Roberto Bresin, Mikael Fernström
Venue: IEEE MultiMedia (2003)

Interactive systems, virtual environments, andinformation display applications need dynamic soundmodels rather than faithful audio reproductions.This implies three levels of research: auditoryperception, physics-based sound modeling, and expres-siveparametric control. Parallel progress along thesethree lines leads to effective auditory displays that cancomplement or substitute visual displays.
A conceptual framework enabling assessment of software flexibility in business applications
Authors: Stephen L. Dyer
Venue: Adaptive evolutionary information systems (2003)

This chapter discusses the design of a technique for measuring the flexibility of business information systems. It argues that a technique for measuring software flexibility can be designed from existing principles using a qualitative approach. It then describes the design process undertaken to develop a software flexibility assessment technique that could be used to assess the adaptive capacity of business software applications.First, the author introduces the background to the subject and gives the justification for developing a suitable business-oriented measure of software flexibility. He then tackles the design issues and problems that arise when confronted with the complexities of qualitative measurement, before describing the steps of the design process. Afterwards, the stages in the application of the technique are described, with a worked example. Finally the benefits and weaknesses of the technique are discussed, and an opinion expressed as to the usefulness and applicability of the proposed technique.
Hyper-systolic algorithms with applications in linear algebra and molecular dynamics
Authors: Th. Lippert, N. Petkov
Venue: Highly parallel computaions: algorithms and applications (2001)

We give an introduction to hyper-systolic algorithms. We address two important applications, N-body computations with long-range interactions and the distributed matrix multiplication.
Anti-lecture hall compositions
Authors: Sylvie Corteel, Carla D. Savage
Venue: Discrete Mathematics (2003)

We study the set Ak of integer sequences λ = (λ1,...,λk), defined by λ1/1 ≥ λ2/2 ≥ ... λk/k ≥ 0 and show that the generating function is Σλ ∈ Ak q|λ| = Πi=1k (1 + qi)/(1 - q i+1), where |λ| = λ1 +...+ λk. We establish this by giving a bijective proof of the following refinement: Σλ ∈ Ak q|λ| u|⌊λ⌋| vo(⌊λ⌋) = Π i = 1 k(1 + uvqi)/(1 - u2qi+1). To our knowledge this is a new result that complements the family of the Lecture Hall Theorems (Ramanujan J. 1(1,2) (1997) 101, 165; J. Combin. Theory Ser. A 86(1) (1999) 63).