ppxscal/embedding_network huggingface dataset:
Optimized strings for the Java HotSpot&trade; virtual machine
Authors: Christian Häubl, Christian Wimmer, Hanspeter Mössenböck
Venue: Proceedings of the 6th international symposium on Principles and practice of programming in Java (2008)

In several Java VMs, strings consist of two separate objects: metadata like the string length are stored in the actual string object, while the string characters are stored in a character array. This separation causes an unnecessary overhead. Each string method must access both objects, which leads to a bad cache behavior and reduces the execution speed. We propose to merge the character array with the string's metadata object at run time. This results in a new layout of strings with better cache performance, fewer field accesses, and less memory overhead. We implemented this optimization for Sun Microsystems' Java HotSpot&trade; VM, so that the optimization is performed automatically at run time and requires no actions on the part of the programmer. The original class String is transformed into the optimized version and the bytecodes of all methods that allocate string objects are rewritten. All these transformations are performed by the Java HotSpot&trade; VM when a class is loaded. Therefore, the time overhead of the transformations is negligible. Benchmarks show a reduction of the average used memory after a full garbage collection and an improved performance. The performance of the SPECjbb2005 benchmark increases by 8%, and the average used memory after a full garbage collection is reduced by 19%. The peak performance of SPECjvm98 is improved by 8% on average, with a maximum speedup of 62%.
Spider Diagrams of Order and a Hierarchy of Star-Free Regular Languages
Authors: Aidan Delaney, John Taylor, Simon Thompson
Venue: Proceedings of the 5th international conference on Diagrammatic Representation and Inference (2008)

The spider diagram logic forms a fragment of the constraint diagram logic and was designed to be primarily used as a diagrammatic software specification tool. Our interest is in using the logical basis of spider diagrams and the existing known equivalences between certain logics, formal language theory classes and some automata to inform the development of diagrammatic logics. Such developments could have many advantages, one of which would be aiding software engineers who are familiar with formal languages and automata to more intuitively understand diagrammatic logics. In this paper we consider relationships between spider diagrams of order (an extension of spider diagrams) and the star-free subset of regular languages. We extend the concept of the language of a spider diagram to encompass languages over arbitrary alphabets. Furthermore, the product of spider diagrams is introduced. This operator is the diagrammatic analogue of language concatenation. We establish that star-free languages are definable by spider diagrams of order equipped with the product operator and, based on this relationship, spider diagrams of order are as expressive as first order monadic logic of order.
Evaluation of Historic Buildings Based on Structural Equation Models
Authors: Qiaohui Tong, Tianzhen Liu, Hengqing Tong, Zhuoling Ou
Venue: Proceedings of the 7th international conference on Computational Science, Part III: ICCS 2007 (2007)

This paper proposes a quantitative method for historic buildings evaluation, which is the essential step before conservation decisions. We introduce Structural Equation Models (SEM) in the evaluation of historic buildings making evaluation more objective. We select certain independent variables and dependent variables, including the first degree and the second degree indexes and relationships among them, and put forward an applicable index system which could be spread in all historic sites.
Smart architecture: semantic agreement aware management of services
Authors: Qian Zhao
Venue:  (2007)

For greater efficiency and lower casts, computer scientists and engineers have been pursuing automation of versatile process management. Highly structured agreements should he able to be executed and enforced automatically. In the progress of building an executable license agreement framework, we have noticed that different agreement processing and automation have something in common, which leads us to propose a generic architecture that is able to provide various automated agreement services by leveraging ontology, rule and agent technologies. Keyword. agreement automation, autonomic computing, knowledge representation, ontology, agent.
Reachability of Uncertain Nonlinear Systems Using a Nonlinear Hybridization
Authors: Nacim Ramdani, Nacim Meslem, Yves Candau
Venue: Proceedings of the 11th international workshop on Hybrid Systems: Computation and Control (2008)

In this paper, we investigate nonlinear reachability computation in presence of model uncertainty, via guaranteed set integration. We show how this can be done by using the classical Müller's existence theorem. The core idea developed is to no longer deal with whole sets but to derive instead two nonlinear dynamical systems which involve no model uncertainty and which bracket in a guaranteed way the space reachable by the original uncertain system. We give a rule for building the bracketing systems. In the general case, the bracketing systems obtained are only piecewise C k -continuously differential nonlinear systems and hence can naturally be modeled with hybrid automata. We show how to derive the hybrid model and how to address mode switching. An example is given with a biological process.
Deadlock-Free Fully Adaptive Routing in 2-Dimensional Tori Based on New Virtual Network Partitioning Scheme
Authors: Dong Xiang, Yi Pan, Qi Wang, Zhen Chen
Venue: Proceedings of the 2008 The 28th International Conference on Distributed Computing Systems (2008)

A new deadlock-free fully adaptive routing algorithm is proposed for 2−dimensional tori with only two virtual channels. The deadlock avoidance technique is presented based on a new virtual network partitioning scheme. Unlike the previous virtual network partitioning schemes, the new method allows all virtual networks to share some common virtual channels. Two virtual channels should be the lower bound for fully adaptive deadlock-free routing in tori because the dimension order routing for 2-dimensional tori also needs two virtual channels. The proposed virtual network partitioning scheme can avoid all potential deadlocks and provides fully adaptive routing. Enough theoretical analyses on the proposed virtual network partitioning scheme are presented. Sufficient simulation results are presented to demonstrate the effectiveness of the proposed algorithm by comparing with the dimension-order routing, two partially adaptive routing schemes, Duato's protocol and the load-balanced routing algorithm GOAL.
An EM-Based Piecewise Linear Regression Algorithm
Authors: Sebastian Nusser, Clemens Otte, Werner Hauptmann
Venue: Proceedings of the 3rd international workshop on Hybrid Artificial Intelligence Systems (2008)

This contribution describes an EM-like piecewise linear regression algorithm that uses information about the target variable to determine a meaningful partitioning of the input space. The main goal of this approach is to incorporate information about the target variable in the prototype selection process of a piecewise regression approach. Furthermore, the proposed approach is designed to provide an interpretable solution by restricting the dimensionality of the local regression models. We will show that our approach achieves a similar predictive performance on benchmark problems compared to standard regression methods --- while the model complexity of our approach is reduced.
Topic 11 Distributed and High-Performance Multimedia
Authors: Harald Kosh, Laurent Amsaleg, Eric Pauwels, Björn Jónsson
Venue: Proceedings of the 13th European international conference on Parallel Processing (2007)

In recent years, the world has seen a tremendous increase in the capability to create, share and store multimedia items, i.e. a combination of pictorial, linguistic, and auditory data. Moreover, in emerging multimedia applications, generation, processing, storage, indexing, querying, retrieval, delivery, shielding, and visualization of multimedia content are integrated issues, all taking place at the same time and - potentially - at different administrative domains. As a result of these trends, a number of novel and hard research questions arise, which can be answered only by applying techniques of parallel, distributed, and Grid computing.
Graphics Hardware-Based Level-Set Method for Interactive Segmentation and Visualization
Authors: Helen Hong, Seongjin Park
Venue: Proceedings of the 7th international conference on Computational Science, Part II (2007)

This paper presents an efficient graphics hardware-based method to segment and visualize level-set surfaces as interactive rates. Our method is composed of memory manager, level-set solver, and volume renderer. The memory manager which performs in CPU generates page table, inverse page table and available page stack as well as process the activation and inactivation of pages. The level-set solver computes only voxels near the iso-surface. To run efficiently on GPUs, volume is decomposed into a set of small pages. Only those pages with non-zero derivatives are stored on GPU. These active pages are packed into a large 2D texture. The level-set partial differential equation (PDE) is computed directly on this packed format. The memory manager is used to help managing the packing of the active data. The volume renderer performs volume rendering of the original data simultaneouly with the evo-lving level set in GPU. Experimental results using two chest CT datasets show that our graphics hardware-based level-set method is much faster than software-based one.
Queues, latency and critical phenomena in interconnection networks
Authors: Lev B. Levitin
Venue:  (2008)

The analysis of the network performance as networks of queues is a well-known approach. We consider networks modeled as rings and as 2-dimensional toroidal square lattices of nodes, with characteristics, which are different of whose discussed in previous works. Time is discrete, and the service time is deterministic. First, we consider homogeneous networks. The buffers capacity is assumed to be infinite and every node generates messages with the same probability &lambda;. We derive explicit analytical expressions for the queue length distribution, the average number of messages in buffers, and the latency (average delay) using the assumption that the distribution of network states has a product form. It is shown that the network experiences a second-order phase transition from equilibrium to the saturation regime, and the critical exponent is equal to 1. The critical network load is found and shown to be inversely proportional to the distance between the source and destination. Simulation results demonstrate an excellent agreement with theoretical predictions and validate the assumption of independent queues (analogous to the mean field theory in statistical physics). Next, we obtain and discuss theoretical and numerical results for networks with strong correlation between nodes: networks with heterogeneous activity where probability to generate messages changes depending on the message flow to a particular router, and networks with limiting buffers. Both types of networks display behavior completely different from that of homogeneous activity networks with infinite buffers, once the load approaches the critical value. The emergence of the structure of two phases in a dynamic equilibrium with each other, similar to systems in statistical physics, and non-trivial values of the critical exponent show that we deal with a collective phenomenon, which cannot be accurately described within the framework of the "mean field" theory. Thus, the "independent queues" hypothesis is not valid, and Jackson's theorem does not apply anymore. Both second-order and first-order phase transitions have been observed in networks with finite buffers. Fluctuations with very large amplitudes, slowly changing in time, and instabilities in critical region are characteristic features of the network behavior, similar to those of critical phenomena in physical systems.
Support, Relevance and Spectral Learning for Time Series
Authors: Bernardete Ribeiro
Venue: Proceedings of the 8th international conference on Adaptive and Natural Computing Algorithms, Part II (2007)

This paper proposes the Spectral Clustering Kernel Machine (SCKM) for times series prediction. Support Vector Machine (SVM), Relevance Vector Machine (RVM) and the Spectral Clustering Kernel Machine (SCKM) are compared in terms of performance accuracy for a simple time series approximation problem. The three outlined algorithms each of which with interesting features to perform automated learning are examined, analysed and empirically tested. In case of the SVM, our tests combine also a preprocessing stage including Kohonen Maps (SOM) as well as K-means clustering. In the case of RVM we also implemented a constructive approach based on the fast marginal likelihood maximization described in [14]. Prediction results in two benchmark time series have been addressed using various performance metrics. The results demonstrate that whereas RVM models achieve larger parsimony of the fitted model, both SVM and SCKM attain higher accuracy. The learning models are competitive for real world problems.
Space-Partitioning-Based Bulk-Loading for the NSP-Tree in Non-ordered Discrete Data Spaces
Authors: Gang Qian, Hyun-Jeong Seok, Qiang Zhu, Sakti Pramanik
Venue: Proceedings of the 19th international conference on Database and Expert Systems Applications (2008)

Properly-designed bulk-loading techniques are more efficient than the conventional tuple-loading method in constructing a multidimensional index tree for a large data set. Although a number of bulk-loading algorithms have been proposed in the literature, most of them were designed for continuous data spaces (CDS) and cannot be directly applied to non-ordered discrete data spaces (NDDS). In this paper, we present a new space-partitioning-based bulk-loading algorithm for the NSP-tree -- a multidimensional index tree recently developed for NDDSs . The algorithm constructs the target NSP-tree by repeatedly partitioning the underlying NDDS for a given data set until input vectors in every subspace can fit into a leaf node. Strategies to increase the efficiency of the algorithm, such as multi-way splitting, memory buffering and balanced space partitioning, are employed. Histograms that characterize the data distribution in a subspace are used to decide space partitions. Our experiments show that the proposed bulk-loading algorithm is more efficient than the tuple-loading algorithm and a popular generic bulk-loading algorithm that could be utilized to build the NSP-tree.
Factor structure for Young's Internet Addiction Test: A confirmatory study
Authors: Man Kit Chang, Sally Pui Man Law
Venue: Computers in Human Behavior (2008)

A number of diagnostic scales have been developed in recent years to assess Internet addiction. To better understand the structure, validity, and reliability of such assessment instruments, Young's Internet Addiction Test (IAT) was evaluated using a confirmatory approach. Data collected through a survey of 410 Hong Kong university undergraduates was subjected to exploratory factor analysis and data from a hold-out sample was analyzed using confirmatory factor analysis in order to assess the psychometric properties and factor structure of the IAT scale. Three dimensions, namely, ''Withdrawal and Social Problems'', ''Time Management and Performance'', and ''Reality Substitute'' were extracted. These dimensions were then correlated with a number of criterion variables, including academic performance, online activities, gender, and Internet usage. The results show that academic performance was negatively correlated with the Internet addiction scores. The degree of Internet addiction was also found to vary across different types of online activity, with people engaged in cyberrelationships and online gambling having higher Internet addiction scores.
Psycho-acoustic model-based message authentication coding for audio data
Authors: Sascha Zmudzinski, Martin Steinebach
Venue: Proceedings of the 10th ACM workshop on Multimedia and security (2008)

Existing security algorithms for data authentication like cryptographic hash functions for example, are very sensitive to changes in the protected data by design. If these mechanisms are applied on multimedia data, they fail to distinguish imperceptible signal transformation from malicious tampering that perceivably changes the content. Furthermore, they usually provide no localization or an assessment of the relevance of such manipulations with respect to human perception or even semantics which is not desirable in a number of applications. We present an algorithm for a robust message authentication code (MAC) for digital audio data in the context of authentication watermarking. An existing audio fingerprinting approaches is improved with respect to key-based security. Psychoacoustic modelling is incorporated by us to separate inaudible changes from perceivably relevant modifications of the audio content. Experimental results show that the proposed algorithm provides both a high level of distinction between perceptually different audio data and a high robustness against signal transformations that do not change the perceived information.
Adjustable Trust Model for Access Control
Authors: Maryna Komarova, Michel Riguidel
Venue: Proceedings of the 5th international conference on Autonomic and Trusted Computing (2008)

The purpose of this work is to give a service provider or a resource holder the opportunity to evaluate the trustworthiness of each potential client, react to the client's activity by adapting access policies to the actual risk level, and derive user's access rights from his previous behavior, recommendations from third party and the actual circumstances. It is supposed that the system is able to observe and to log the activity of each client and use this information to estimate correspondent trust values.
Dependent types for safe systems software
Authors: George C. Necula
Venue:  (2007)

The C language is the dominant language for writing systems software, but it permits large classes of programming errors that could be prevented with a more modern language. Unfortunately, it is impractical to simply rewrite all of our existing software; rather, we must focus on a transition path to a more reliable systems programming language. As the first step in an incremental transition to a new language, we must allow programmers to annotate higher-level idioms typically used by C programmers, such as bounded pointers and tagged unions. This thesis presents Deputy, a dependent type framework that allows programmers to annotate existing C code with more refined types. In particular, dependent types allow programmers to relate multiple state elements, such as a pointer and its bounds, or a union and its tag. In doing so, we address several technical hurdles involved with dependent types. First, we address the issue of mutation in the presence of dependencies by using insights from axiomatic semantics. Second, we handle the problem of undecidability by using runtime checks where necessary. Third, we address usability challenges with a novel inference mechanism called automatic dependencies. Once this framework is established, we show how it can be instantiated to support the dependent types required by modern systems code. In addition, we discuss several real-world applications of Deputy, including small and medium-size benchmarks as well as the Linux kernel itself, These benchmarks allow us to evaluate Deputy's annotation burden and performance in the context of real-world code.
Analysis and Comparison of Reordering for Two Factorization Methods (LU and WZ) for Sparse Matrices
Authors: Beata Bylina, Jarosław Bylina
Venue: Proceedings of the 8th international conference on Computational Science, Part I (2008)

The authors of the article make analysis and comparison of reordering for two factorizations of the sparse matrices --- the traditional factorization into the matrices L and U as well as the factorization into matrices W and Z. The article compares these two factorizations regarding: the produced quantity of non-zero elements alias their susceptibility to a fill-in; the algorithms reorganizing matrix (for LU it will be the algorithm AMD but for WZ it will be a modification of the Markowitz algorithm); as well as the time of the algorithms. The paper also describes the results of a numerical experiment carried for different sparse matrices from Davis Collection.
Preliminary Results in a Multi-site Empirical Study on Cross-Organizational ERP Size and Effort Estimation
Authors: Maya Daneva
Venue: Software Process and Product Measurement: International Conference, IWSM-Mensura 2007, Palma de Mallorca, Spain, November 5-8, 2007. Revised Papers (2007)

This paper reports on initial findings in an empirical study carried out with representatives of two ERP vendors, six ERP adopting organizations, four ERP implementation consulting companies, and two ERP research and advisory services firms. Our study's goal was to gain understanding of the state-of-the practice in size and effort estimation of cross-organizational ERP projects. Based on key size and effort estimation challenges identified in a previously published literature survey, we explored some difficulties, fallacies and pitfalls these organizations face. We focused on collecting empirical evidence from the participating ERP market players to assess specific facts about the state-of-the-art ERP size and effort estimation practices. Our study adopted a qualitative research method based on an asynchronous online focus group.
A Practical Attack on the MIFARE Classic
Authors: Gerhard Koning Gans, Jaap-Henk Hoepman, Flavio D. Garcia
Venue: Proceedings of the 8th IFIP WG 8.8/11.2 international conference on Smart Card Research and Advanced Applications (2008)

The mifare Classic is the most widely used contactless smart card in the market. Its design and implementation details are kept secret by its manufacturer. This paper studies the architecture of the card and the communication protocol between card and reader. Then it gives a practical, low-cost, attack that recovers secret information from the memory of the card. Due to a weakness in the pseudo-random generator, we are able to recover the keystream generated by the CRYPTO1 stream cipher. We exploit the malleability of the stream cipher to read all memory blocks of the first sector of the card. Moreover, we are able to read any sector of the memory of the card, provided that we know one memory block within this sector. Finally, and perhaps more damaging, the same holds for modifying memory blocks.
Effective service replication mechanisms exploiting agent mobility
Authors: Jinho Ahn
Venue: Proceedings of the 7th WSEAS International Conference on Software Engineering, Parallel and Distributed Systems (2008)

To enhance scalability of replicated services a large number of mobile agents attempt to access in mobile agent systems, we present a new strategy to apply an appropriate passive replication mechanism to each replicated service according to its execution behavior because deterministic services require weaker constraints to ensure their consistency than non-deterministic ones. For this goal, two passive replication mechanisms are introduced for non-deterministic services and for deterministic services respectively. They both allow visiting mobile agents to be forwarded to and execute on any node performing a service agent, not necessarily the primary agent. Especially, in case of the mechanism for deterministic services, after a backup service agent has received a mobile agent request and obtained the delivery sequence number of the request from the primary service agent, the backup agent, not the primary one, is responsible for processing the request and coordinating with the other replica service agents.