ppxscal/embedding_network huggingface dataset:
Statistical reconstruction algorithms for polyenergetic x-ray computed tomography
Authors: Idris A. Elbakri
Venue:  (2003)

Statistical reconstruction for transmission tomography is emerging as potential alternative to conventional analytic image reconstruction. To fully realize their potential in noise reduction and image quality improvement, statistical algorithms should be based upon a system model that incorporates measurement statistics, attenuation physics and system parameters. CT measurements are often assumed to follow Poisson statistics. CT detectors, however, are energy integrators that give rise to more complex compound Poisson statistics. We derive the compound Poisson probability mass function and a practical but approximate likelihood. The likelihood is based on a statistical model that accounts for energy-dependent statistics, Poisson scintillation light and electronic additive Gaussian noise. We compare the approximate likelihood with the ordinary Poisson and exact likelihoods. The approximate likelihood is more accurate than the ordinary Poisson likelihood in low count situations, and may be useful for image reconstruction in such situations. We derive a polyenergetic statistical X-ray CT reconstruction algorithm. The algorithm is based on polyenergetic X-ray attenuation physics and has been derived for objects containing an arbitrary number of materials. The algorithm derivation involves successive application of the optimization transfer principle to arrive at a simple and easy to maximize cost function. The algorithm requires knowledge of the X-ray spectrum or related measurements and a pre-segmented map of the distributions of different tissues within the image. Such a map is available from FBP reconstruction. The pre-segmentation map keeps the number of unknowns in the reconstruction problem equal to the number of pixels. In this regard the algorithm is comparable to conventional beam hardening correction methods. The algorithm is a gradient descent algorithm that can be accelerated using ordered subsets and a precomputed curvature. It is also possible to derive a curvature that guarantees monotonicity. We use the algorithm to reconstruct objects that contain materials that can be categorized as bone and (water-like) soft tissue. The iterative algorithm is superior to conventional beam hardening reduction methods in terms of artifact suppression and noise reduction. To relax the requirement for a pre-segmentation map, we propose object models that parameterize the scanned object in terms of spatial and energy components. (Abstract shortened by UMI.)
Virtual Spaces as Artifacts: Implications for the Design of Educational CVEs
Authors: Ekaterina Prasolova-Frland
Venue: Proceedings of the 2003 International Conference on Cyberworlds (2003)

Space is important for learning and socializing.Cyberworlds provide a new space for socialization andcommunication with a great degree of flexibility, allowingusers to create and manipulate virtual land. This suggestsconsidering virtual spaces as artifacts. In this paper weuse different theoretical approaches on artifacts andexperiences of usage of a virtual world we have createdto revise the original design and to derive a new set ofrequirements for virtual places and spatial artifacts.
Cost efficient broadcast based cache invalidation for mobile environments
Authors: Kwong Yuen Lai, Zahir Tari, Peter Bertok
Venue: Proceedings of the 2003 ACM symposium on Applied computing (2003)

To improve the performance of mobile computers, a number of broadcast based cache invalidation schemes have been proposed in the past to support object locality. However most of these schemes have focused on providing support for client disconnection and reducing query delay. The size of invalidation reports and the effect of invalidating items cached by many clients are also important issues that must be addressed in order to provide cost-efficient cache invalidation in a mobile environment. In this paper, we propose two techniques, Validation-Invalidation Reports (VIR) and the Delayed Requests Scheme (DRS) to address these issues. VIR uses a combination of validation and invalidation reports, allowing the server to construct and broadcast smaller reports at each interval, thus improving downlink channel utilization. DRS addresses the problem where multiple clients request for the same data items. It introduces a "cool down" period after an invalidation, to reduce the number of uplink requests sent by clients. Simulation results show that compared to the original TS approach [1], the proposed schemes lower transmission cost associated with cache invalidation by between 5%-25% in the downlink channel and between 10%-40% in the uplink channel.
Game Theoretic Modeling of Voltage and Frequency Scaling during Behavioral Synthesis
Authors: Ashok K. Murugavel, N. Ranganathan
Venue: Proceedings of the 17th International Conference on VLSI Design (2004)

Frequency scaling has recently become an importantarea for exploration with respect to power and energyoptimization. In this work, we describe a new methodology forsimultaneous voltage and frequency scaling during schedulingin behavioral synthesis based on game theory for power andenergy reduction. The problem of scheduling in synthesis isformulated as an auction based non-cooperative finite game, forwhich solutions are developed based on the Nash equilibriumfunction. Each operation in the data-path is modeled as a playerbidding for executing an operation in the given control cycle, withthe estimated power consumption as the bid. We develop gametheoretic models and propose a resource constrained algorithm.Experimental results on selected benchmark circuits show thatthe proposed algorithm yields about 42.5% energy savings onthe average.
An information dissemination service for ubiquitous computing applications
Authors: Stephen S. Yau
Venue:  (2003)

In many ubiquitous computing (ubiquitous computing) applications, such as smart classrooms, hospitals, construction sites, stadiums, shopping malls, emergency services, law-enforcement, convention centers, battlefields, and inhospitable physical environments, an information dissemination service is needed for distributing information from one or more devices to a set of devices. Information dissemination for ubiquitous computing applications can be achieved by autonomous coordination, but complex interactions and autonomous coordination of these devices depend upon local and neighboring contexts and/or situations. Due to the mobility of the devices, unknown destinations for information from a source, and low computational power of the devices for routing, it is difficult to provide an information dissemination service for ubiquitous computing applications. In this dissertation, an approach to developing an information dissemination service for ubiquitous computing applications is presented. The information dissemination has been developed on the test bed and incorporated in Reconfigurable Context-sensitive Middleware (RCSM). RCSM has been used for the applications in ubiquitous computing environments since it can provide context-sensitivity, situation-awareness, and ad hoc communication. A set of simulation tools has been developed to show the effectiveness of the approach for large number of devices. Experimental results from both implementations on the test bed and simulations are presented.
Optimal design of flywheels using an injection island genetic algorithm
Authors: David Eby, R. C. Averill, William F. Punch,  III, Erik D. Goodman
Venue: Artificial Intelligence for Engineering Design, Analysis and Manufacturing (1999)

This paper presents an approach to optimal design of elastic flywheels using an Injection Island Genetic Algorithm (iiGA), summarizing a sequence of results reported in earlier publications. An iiGA in combination with a structural finite element code is used to search for shape variations and material placement to optimize the Specific Energy Density (SED, rotational energy per unit weight) of elastic flywheels while controlling the failure angular velocity. iiGAs seek solutions simultaneously at different levels of refinement of the problem representation (and correspondingly different definitions of the fitness function) in separate subpopulations (islands). Solutions are sought first at low levels of refinement with an axi-symmetric plane stress finite element code for high-speed exploration of the coarse design space. Next, individuals are injected into populations with a higher level of resolution that use an axi-symmetric three-dimensional finite element code to &ldquo;fine-tune&rdquo; the structures. A greatly simplified design space (containing two million possible solutions) was enumerated for comparison with various approaches that include: simple GAs, threshold accepting (TA), iiGAs and hybrid iiGAs. For all approaches compared for this simplified problem, all variations of the iiGA were found to be the most efficient. This paper will summarize results obtained studying a constrained optimization problem with a huge design space approached with parallel GAs that had various topological structures and several different types of iiGA, to compare efficiency. For this problem, all variations of the iiGA were found to be extremely efficient in terms of computational time required to final solution of similar fitness when compared to the parallel GAs.
Organizational Design of Post Corporation Structure Using Fuzzy Multicriteria Decision Making
Authors: Momčilo Kujačić, Nebojša J. Bojović
Venue: Computational Mathematical Organization Theory (2003)

A model for organizational design of post corporation structure is developed in this paper. Alternative organization solutions have been designed taking into account the post environment characterized by private operators' competition and development of new message transmission technologies. Criteria for organizational design have been considered as numerical and uncertain linguistic variables describes by fuzzy sets. The model has been tested on a numerical example.
AI in Computer Games
Authors: Alexander Nareyek
Venue: Queue (2004)

If you’ve been following the game development scene, you’ve probably heard many remarks such as: “The main role of graphics in computer games will soon be over; artificial intelligence is the next big thing!” Although you should hardly buy into such statements, there is some truth in them. The quality of AI (artificial intelligence) is a high-ranking feature for game fans in making their purchase decisions and an area with incredible potential to increase players’ immersion and fun.
A language development environment for Eclipse
Authors: M. G. J. van den Brand, H. A. de Jong, P. Klint, A. T. Kooiker
Venue: Proceedings of the 2003 OOPSLA workshop on eclipse technology eXchange (2003)

The ASF+SDF Meta-Environment provides a collection of tools for the generation of programming environments. We show how Eclipse can be extended with these generic language tools. By integrating the GUI and text editor of the Meta-Environment with Eclipse using TOOLBUS technology, we demonstrate the integration of third party, non-Java, software in Eclipse. By doing so, we create an experimentation framework for further programming language research. We describe our experiences and sketch future work.
Searching and mining the web for personalized and specialized information
Authors: Michael Chiu-Lung Chau
Venue:  (2003)

With the rapid growth of the Web, users are often faced with the problem of information overload and find it difficult to search for relevant and useful information on the Web. Besides general-purpose search engines, there exist some alternative approaches that can help users perform searches on the Web more effectively and efficiently. Personalized search agents and specialized search engines are two such approaches. The goal of this dissertation is to study how machine learning and artificial intelligence techniques can be used to improve these approaches. A system development research process was adopted as the methodology in this dissertation. In the first part of the dissertation, five different personalized search agents, namely CI Spider, Meta Spider, Cancer Spider, Nano Spider, and Collaborative Spider, were developed. These spiders combine Web searching with various techniques such as noun phrasing, text clustering, and multi-agent technologies to help satisfy users' information needs in different domains and different contexts. Individual experiments were designed and conducted to evaluate the proposed approach and the experimental results showed that the prototype systems performed better than or comparable to traditional search methods. The second part of the dissertation aims to investigate how artificial intelligence techniques can be used to facilitate the development of specialized search engines. A Hopfield Net spider was proposed to locate from the Web URLs that are relevant to a given domain. A feature-based machine-learning text classifier also was proposed to perform filtering on Web pages. A prototype system was built for each approach. Both systems were evaluated and the results demonstrated that they both outperformed traditional approaches. This dissertation has two main contributions. Firstly, it demonstrated how machine learning and artificial intelligence techniques can be used to improve and enhance the development of personalized search agents and specialized search engines. Secondly, it provided a set of tools that can facilitate users in their Web searching and Web mining activities in various contexts.
Task analysis for groupware usability evaluation: Modeling shared-workspace tasks with the mechanics of collaboration
Authors: David Pinelle, Carl Gutwin, Saul Greenberg
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (2003)

Researchers in Computer Supported Cooperative Work have recently developed discount evaluation methods for shared-workspace groupware. Most discount methods rely on some understanding of the context in which the groupware systems will be used, which means that evaluators need to model the tasks that groups will perform. However, existing task analysis schemes are not well suited to the needs of groupware evaluation: they either do not deal with collaboration issues, do not use an appropriate level of analysis for concrete assessment of usability in interfaces, or do not adequately represent the variability inherent in group work. To fill this gap, we have developed a new modeling technique called Collaboration Usability Analysis. CUA focuses on the teamwork that goes on in a group task rather than the taskwork. To enable closer links between the task representation and the groupware interface, CUA grounds each collaborative action in a set of group work primitives called the mechanics of collaboration. To represent the range of ways that a group task can be carried out, CUA allows variable paths through the execution of a task, and allows alternate paths and optional tasks to be modeled. CUA's main contribution is to provide evaluators with a framework in which they can simulate the realistic use of a groupware system and identify usability problems that are caused by the groupware interface.
The Construction of BCA in China
Authors: Yuanhang Liu, Xian Liu, Jiubin Ju
Venue: Proceedings of the 2003 International Conference on Computer Networks and Mobile Computing (2003)

For cross-certification in the PKI, there are many mechanisms in the reality. This paper provides a high level view of the various "dimensions" involved in achieving PKI inter-operability and analyzes the advantages and the disadvantages of each method. At the end of the paper we bring forward the BCA mechanism in China (CNBCA) and talk about the demonstration phase of the CABCA.
Inplace 2D matching in compressed images
Authors: Amihood Amir, Gad M. Landau, Dina Sokol
Venue: Journal of Algorithms (2003)

The compressed matching problem is the problem of finding all occurrences of a pattern in a compressed text. In this paper we discuss the 2-dimensional compressed matching problem in Lempel-Ziv compressed images. Given a pattern P of (uncompressed) size m × m, and a text T of (uncompressed) size n × n, both in 2D-LZ compressed form, our algorithm finds all occurrences of P in T. The algorithm is strongly inplace, that is, the amount of extra space used is proportional to the best possible compression of a pattern of size m2. The best compression that the 2D-LZ technique can obtain for a file of size m2 is O(m). The time for performing the search is O(n2) and the preprocessing time is O(m3). Our algorithm is general in the sense that it can be used for any 2D compression which can be sequentially decompressed in small space.
Computer aided dimensional analysis for knowledge management in chemical engineering processes
Authors: F. A. Batzias, A. S. Kakos, N. P. Nikolaou
Venue: Proceedings of the international conference on Computational methods in sciences and engineering (2003)

An algorithmic procedure has been designed/developed for Computer Aided Dimensional Analysis (DA) of chemical engineering processes. The main purpose of this software is to construct/select the best combination of dimensionless groups describing adequately a process under certain criteria. The creation/operation of an Ontological Knowledge Base (OKB) plays a central role in this procedure as it provides, inter alia the means for filtering/reducing the dimensionless groups obtained by solving the system of dimensional equations according to the Buckingham Π Theorem. The successful implementation of this software is thoroughly presented step by step in a case of mass transfer (liquid drops moving in immiscible liquids).
A pipelined schedule to minimize completion time for loop tiling with computation and communication overlapping
Authors: N. Koziris, A. Sotiropoulos, G. Goumas
Venue: Journal of Parallel and Distributed Computing (2003)

This paper proposes a new method for the problem of minimizing the execution time of nested for-loops using a tiling transformation. In our approach, we are interested not only in tile size and shape according to the required communication to computation ratio, but also in overall completion time. We select a time hyperplane to execute different tiles much more efficiently by exploiting the inherent overlapping between communication and computation phases among successive, atomic tile executions. We assign tiles to processors according to the tile space boundaries, thus considering the iteration space bounds. Our schedule considerably reduces overall completion time under the assumption that some part from every communication phase can be efficiently overlapped with atomic, pure tile computations. The overall schedule resembles a pipelined datapath where computations are not anymore interleaved with sends and receives to nonlocal processors. We survey the application of our schedule to modern communication architectures. We performed two sets of experimental results, one using MPI primitives over FastEthernet and one using the SISCI API over an SCI network. In both cases, the total completion time is significantly reduced.
Variants of relaxed schemes and two-dimensional gas dynamics
Authors: Mapundi K. Banda
Venue: Proceedings of the international conference on Computational methods in sciences and engineering (2003)

We present a relaxed scheme with more precise information about local speeds of propagation and a multidimensional construction of the cell averages. Hence the physical domain of dependence is simulated correctly and high resolution is maintained by a genuinely multidimensional piecewise nonoscillatory reconstruction. Relaxation schemes have advantages that include high resolution, simplicity and explicitly no (approximate) Riemann solvers and characteristic decomposition is necessary. Performance of the scheme is illustrated by tests on two-dimensional Euler equations of gas dynamics.
Effectiveness of automatic and expert generated narrative and guided instructions for task-oriented web browsing
Authors: Guangfeng Song, Gavriel Salvendy
Venue: International Journal of Human-Computer Studies (2003)

This study investigated how instructions may be created to facilitate web browsing tasks. Two types of instructions were considered. Narrative instructions are text-based while guided instructions use graphic annotations. One way to create both types of instructions is to utilize the specialty of human experts. A method is also provided for automatic generation of both types of instructions based on the learning of user experience in web browsing. An experiment was conducted to test the effect of types of instruction, sources of instruction, and task complexity setting on performance variables in web browsing. The results of the experiment indicated that (1) by using web annotations, guided instructions resulted in better performance and satisfactions than narrative instructions in web browsing, (2) based on learning of web browsing activities, automatically generated guided instructions are comparable to expert-created guided instructions in terms of their effect on the performance of web browsing.
An Advanced Content Delivery Scheduling Method for Block Multicast Transfer
Authors: ZhengYu Xie, Satoshi Uno, Hideki Tode, Koso Murakami
Venue: Proceedings of the 28th Annual IEEE International Conference on Local Computer Networks (2003)

There is an increasing demand for the technology of contentdistribution, by which each user can request desiredcontent through a network. Because of the low efficiencyof existing systems, we proposed a new block transfer typevideo distribution system called Burst VoD. The Burst VoDsystem aggressively utilizes multicasting, and divides thecontent data into a mass of block files, which it periodicallytransmits to a terminal through a high-speed network, usinga higher rate than the playback speed. However, byusing the scheduling algorithm of the Burst VoD system,when users request the same content from different periods,the VoD server repeatedly transmits the same block files indifferent periods. In this paper, we propose an advancedscheduling algorithm based on the Burst VoD system to improveits multicasting efficiency. In addition, we proposea multi-channel BurstVoD in order to reduce the interfacebandwidth of client.
Singular Perturbations in Infinite-Dimensional Control Systems
Authors: T. D. Donchev, A. L. Dontchev
Venue: SIAM Journal on Control and Optimization (2003)

In this paper, we consider a singularly perturbed control system involving differential inclusions in Banach spaces with slow and fast solutions. Using the averaging approach, we obtain sufficient conditions for the Hausdorff convergence of the set of slow solutions in the supremum norm. We present applications of the theorem to prove convergence of the fast solutions in terms of invariant measures and convergence of equi-Lipschitz solutions.
Part-selection triptych: A representation, problem properties and problem definition, and problem-solving method
Authors: Timothy P. Darr, William P. Birmingham
Venue: Artificial Intelligence for Engineering Design, Analysis and Manufacturing (2000)

In part-selection problems, parts are selected from catalogs and connected to meet the following problem requirements: functionality, specifications, and constraints. This paper formally defines the part-selection problem, enumerates a set of design properties that are useful during a search for a design solution, and provides an algorithm for solving part-selection problems based on a novel set of operators for manipulating portions of the design space.