ppxscal/embedding_network huggingface dataset:
Irreversible k-threshold processes: Graph-theoretical threshold models of the spread of disease and of opinion
Authors: Paul A. Dreyer,  Jr., Fred S. Roberts
Venue: Discrete Applied Mathematics (2009)

We will consider models of the spread of disease or opinion through social networks, represented as graphs. In our models, vertices will be in one of two states, 1 (''infected'') or 0 (''uninfected'') and change of state will take place at discrete times. After describing several such models, we will concentrate on the model, called an irreversible k-threshold process, where a vertex enters state 1 if at least k of its neighbors are in state 1, and where a vertex never leaves state 1 once it is in it. We will seek sets of vertices with the property that, if they are in state 1 at the beginning, then eventually all vertices end up in state 1. Such vertex sets correspond to vertices that can be infected with a disease or opinion so as to guarantee saturation of the population with the disease or opinion. We will also discuss ways to ''defend'' against such saturating sets, for example by ''vaccination'' or designing network topologies.
Content distribution for publish/subscribe services
Authors: Mao Chen, Andrea LaPaugh, Jaswinder Pal Singh
Venue: Proceedings of the ACM/IFIP/USENIX 2003 International Conference on Middleware (2003)

Caching and content delivery are important for content-intensive publish/subscribe applications. This paper proposes several content distribution approaches that combine match-based pushing and access-based caching, based on users' subscription information and access patterns. To study the performance of the proposed approaches, we built a simulator and developed a workload to mimic the content and access dynamics of a busy news site. Using a purely access-based caching approach as the baseline, our best approaches yield over 50% and 130% relative gains for two request traces in terms of the hit ratio in local caches, while keeping the traffic overhead comparable. Even when the subscription information is assumed not to reflect users' accesses perfectly, our best approaches still have about 40% and 90% relative improvement for the two traces. To our knowledge, this work is the first effort to investigate content distribution under the publish/subscribe paradigm.
Memory resource allocation for file system prefetching: from a supply chain management perspective
Authors: Zhe Zhang, Amit Kulkarni, Xiaosong Ma, Yuanyuan Zhou
Venue: Proceedings of the 4th ACM European conference on Computer systems (2009)

As an important technique to hide disk I/O latency, prefetching has been widely studied, and dynamic adaptive prefetching techniques have been deployed in diverse storage environments. However, two issues are not well addressed by previous research: (1) how to handle the prefetching resource allocation between concurrent sequential access streams with different request rates, and (2) how to coordinate prefetching at multiple levels in the data access path. Interestingly, we found that these problems bear a strong resemblance to situations long studied in the field of supply chain management (SCM), used by retailers such as Wal-Mart. In this paper, we demonstrate how to perform the problem mapping and then apply SCM principles in practice, particularly from the branch of inventory theory, to improve data prefetching performance in storage systems. More specifically, we applied (1) two SCM policies to dynamically configure the sequential prefetching parameters, and (2) an SCM solution to correct the access pattern information distortion in multi-level prefetching. We implemented these SCM-based strategies in the Linux kernel prefetching algorithm and a multi-level storage simulator, and evaluated the performance with three types of workloads. The results indicate that the SCM approaches are able to generate up to a 55.0% of performance improvement for a real-world server workload benchmark, and up to 33.3% for a combination of Linux I/O-intensive applications.
An Efficient Framework for Configurable Video Encoder
Authors: Wei Li, Bing Zhou
Venue: International Journal of Distributed Sensor Networks (2009)

The implementation of real-time video coding systems with limited resources such as memory volume and CPU speed is a challenging task. In this paper, an efficient embedded multi-modal MPEG-4 video encoder (EMVC) is proposed and implemented to meet the requirement of encoding different modals (colors, resolutions, and bandwidths) video in size and power-restricted scenario. The hardware framework of EMVC is based on FPGA and DSP, which takes full advantage of the strongpoint of DSP and FPGA—powerful digital signal processing ability of DSP is utilized to complete most of the complex video coding, and flexible configuration, the parallelism and high speed of FPGA cooperates to accomplish logical control and auxiliary functions in video coding. The hardware framework is designed with strong processing ability, flexible configuration, and extensive coverage. In software design, we first improve some key algorithms in MPEG-4 standard that have great impact on coding efficiency, a fast motion estimation algorithm—smooth motion vector field adaptive search technique (SMVFAST) and a DSP-based efficient quantization computation method—EQ4DSP are put forward respectively; second, according to the characters of DSP's hardware resource, the encoder software is optimized at system and code levels. At the system level, EDMA (Enhanced Direct Memory Access) channels in DSP are used to parallel the data transfer, and the software structure of the video encoders is changed from frame-based to GMB-based (Group of Macro-Block) to make use of the parallel processing capacity of DSP. At code level, the codes of the frequently called modules in the encoder are the critical optimized part, and the main code optimization methods used in EMVC include: using an intrinsic function to replace the complicated C/C++ code, using packed data processing to maximize the data throughput, unrolling the loop to increase software pipelines, translating C code to Linear Assembly, and so on. By making use of the reserved user-data field in the MPEG-4 standard syntax, a multi-modal function of EMVC is realized, namely, the system can switch among 720 × 576 and 352 × 288 resolutions, grey and color video, 2 M and 256 K bandwidth. Moreover, the mode switch can be achieved in real time according to the input control command. Experimental results show that EMVC not only runs efficiently but also has good flexibility and generality. Furthermore, by realizing diverse video or image coding algorithms, it can also satisfy the requirements of various embedded video applications, especially those with strict restriction in size, power consumption, and control flexibility.
The IMS 2.0 Service Architecture
Authors: Menuka Jain, Maria Prokopi
Venue: Proceedings of the 2008 The Second International Conference on Next Generation Mobile Applications, Services, and Technologies (2008)

This paper examines the driving forces behind the IP Multimedia Subsystem (IMS) and the Web 2.0 worlds. IMS moves operators' vertically integrated model to a horizontal infrastructure, enabling operators to reduce operating and capital expenses. On the other hand, Web 2.0 reflects the change of people's views about technology. Web 2.0 embodies a new perception of the network as a platform, which revolutionizes the world with services such as social networking sites. This paper explores the benefits of using the synergies of both the IMS and the Web 2.0 world. In pursuit of this purpose, the IMS 2.0 service architecture concept is proposed. The IMS 2.0 service architecture's goal is to combine the IMS and Web 2.0 worlds, namely, by opening up IMS assets to the Web 2.0 world, adopting Web 2.0 principles in the IMS world and providing an environment that would facilitate converged applications to users
A simple method to test the stability of 2-D recursive digital filters of second order
Authors: R. Ramesh, P. S. Reddy
Venue: Proceedings of the 8th conference on Signal processing, computational geometry and artificial vision (2008)

Several methods for testing stability of first quadrant quarter-plane two dimensional (2-D) recursive digital filters have been suggested in 1970's and 80's. Though Jury's row and column algorithms, row and column concatenation stability tests have been considered highly efficient they still fall short of accuracy if the computational time is a major consideration. In this paper, we present procedurally very simple algebraic method requiring only two steps when applied to the second order 2-D quarter - plane filter. We extend the same method to the second order Non-Symmetric Half-plane (NSHP) filters. Enough examples are given for both these types of filters as well as some lower order general recursive 2-D digital filters. We applied our method to barely stable or barely unstable filter examples available in the literature and got the same decisions thus showing that our method is accurate enough.
Performance of ten rainfall-runoff models applied to an arid catchment in Oman
Authors: Neil McIntyre, Aisha Al-Qurashi
Venue: Environmental Modelling Software (2009)

When selecting a rainfall-runoff model for application to an arid region, the literature dictates the need to consider the spatial features of rainfall and the variability and non-linearity of losses, and to match model complexity to the availability and quality of data. In light of this, the metric-conceptual IHACRES model is applied to hourly data from a 734km^2 catchment in Oman, using a semi-distributed representation of rainfall input. Sensitivity analysis is used to guide reduction of the model from a 9-parameter version to simpler versions. The performances of the alternative versions, for predicting flow volumes and peaks at the catchment outlet, are inter-compared. Performances are also compared with those achieved using lumped versions of IHACRES, a physics-based model and a 2-parameter regression model. For peak flows, a 2-parameter non-linear loss model with 2-parameter linear routing, applied in semi-distributed mode, achieves the best overall performance. For flow volumes, the same model was preferred although the routing component was not required. The principal reasons for the success of these models are thought to be their parsimony, representation of spatial rainfall, and ability to compensate for systematic rainfall and flow observation errors. Extra performance is achieved by using a score-based calibration criterion, which is more robust to extreme errors than the fit-based criteria. Although the best performances are poor, with an average absolute relative error across events of 53% for flow peaks and 36% for flow volumes, this is not disappointing compared to other applications of this type. Prediction uncertainty is high due to variability of effective parameter values over events, and uncertainty analysis must explicitly represent this variability in order to explain the observations.
Confining windows inter-process communications for OS-level virtual machine
Authors: Zhiyong Shan, Yang Yu, Tzi-cker Chiueh
Venue: Proceedings of the 1st EuroSys Workshop on Virtualization Technology for Dependable Systems (2009)

As OS-level virtualization technology usually imposes little overhead on virtual machine start-up and running, it provides an excellent choice for building intrusion/fault tolerant applications that require redundancy and frequent invocation. When developing Windows OS-level virtual machine, however, people will inevitably face the challenge of confining Windows Inter-Process Communications (IPC). As IPC on Windows platform is more complex than UNIX style OS and most of the programs on Windows are not open-source, it is difficult to discover all of the performed IPCs and confine them. In this paper, we propose three general principles to confine IPC on Windows OS and a novel IPC confinement mechanism based on the principles. With the mechanism, for the first time from the literature, we successfully virtualized RPC System Service (RPCSS) and Internet Information Server (IIS) on Feather-weight Virtual Machine (FVM). Experimental results demonstrate that multiple IIS web server instances can simultaneously run on single Windows OS with much less performance overhead than other popular VM technology, offering a good basis for constructing dependable system.
An Overview of Web Research in Chile
Authors: Claudio Gutierrez, Mauricio Marin
Venue: Proceedings of the 2008 Latin American Web Conference (2008)

Research on topics related to Internet dates in Chile since the verybeginning of its deployment in the country. Research onWeb issues date from the late nineties, and was consolidated with the creation of the Center for WebResearch (CWR) in the year 2002. A relevant by-product of the CWR'sactivities was the recent opening of a Yahoo! research laboratory atSantiago of Chile. In this paper we survey the lines of research on the Webwhich have been pursued in Chile.
Grammar theory based on lattice-ordered monoid
Authors: Xiuhong Guo
Venue: Fuzzy Sets and Systems (2009)

Motivated by Li and Pedrycz's work on fuzzy finite automata and fuzzy regular expressions with membership values in lattice-ordered monoids and inspired by the close relationship between the automata theory and the theory of formal grammars, we have established a fundamental framework of L-valued grammar. It is shown that the set of L-valued regular languages coincides with the set of L-languages recognized by nondeterministic L-fuzzy finite automata and every L-language recognized by a deterministic L-fuzzy finite automaton is an L-valued regular language.
Introduction to social network analysis
Authors: Panayiotis Zaphiris, Ulrike Pfeil
Venue: Proceedings of the 21st British HCI Group Annual Conference on HCI 2008: People and Computers XXI: HCI...but not as we know it - Volume 2 (2007)

Online communities and social software are revolutionizing the way we interact with the web. Analysing the interactions that take place there is complex. Social Network Analysis (SNA) is a powerful way of doing such analysis. This tutorial provides a detailed introduction to SNA. The theory is backed up with a number of practical case studies.
SmartOpt: an industrial strength framework for logic synthesis
Authors: Stephen Jang, Dennis Wu, Mark Jarvin, Billy Chan, Kevin Chung, Alan Mishchenko, Robert Brayton
Venue: Proceeding of the ACM/SIGDA international symposium on Field programmable gate arrays (2009)

In recent years, the maximum logic capacity of each successive FPGA family has been increasing by more than 50%, which motivates scalable solutions. Meanwhile, academic research in logic synthesis has been fruitful, but these advances have been demonstrated on academic architectures and benchmark designs which are not representative of modern industrial FPGAs. This paper presents a framework (SmartOpt) for mapping complex FPGA architectures to a simple netlist model, which can be supported by academic tools. SmartOpt was applied to leverage the algorithms implemented in the ABC package and to study their relative contributions. This work is integrated into the Xilinx ISE 11.1 software flow for FPGAs and shows significant improvements in both the LUT count and performance of large industrial circuits described in HDL. Xilinx Synthesis Technology (XST) reference flow was compared experimentally against the same flow augmented by SmartOpt. When applied to a set of 20 large industrial Virtex-5 benchmarks ranging from 17K to 69K 6-LUTs, the augmented flow produced 8.3% fewer LUTs and led to 2.1% higher operating frequency while keeping runtimes reasonable. With dual-LUT-merging, the LUT count is reduced by 22.7%, while increasing the operating frequency only by 0.7%.
Communication-Aware Supernode Shape
Authors: Georgios Goumas, Nikolaos Drosinos, Nectarios Koziris
Venue: IEEE Transactions on Parallel and Distributed Systems (2009)

In this paper we revisit the supernode-shape selection problem, that has been widely discussed in bibliography. In general, the selection of the supernode transformation greatly affects the parallel execution time of the transformed algorithm. Since the minimization of the overall parallel execution time via an appropriate supernode transformation is very difficult to accomplish, researchers have focused on scheduling-aware supernode transformations that maximize parallelism during the execution. In this paper we argue that the communication volume of the transformed algorithm is an important criterion, and its minimization should be given high priority. For this reason we define the metric of the per process communication volume and propose a method to miminize this metric by selecting a communication-aware supernode shape. Our approach is equivalent to defining a proper Cartesian process grid with MPI_Cart_Create, which means that it can be incorporated in applications in a straightforward manner. Our experimental results illustrate that by selecting the tile shape with the proposed method, the total parallel execution time is significantly reduced due to the minimization of the communication volume, despite the fact that a few more parallel execution steps are required.
Understanding the determinants of EKR usage from social, technological and personal perspectives
Authors: Tung-Ching Lin, Chien-Chih Huang
Venue: Journal of Information Science (2009)

With the capacity to provide the necessary infrastructure to implement knowledge management processes, electronic knowledge repositories (EKRs) have gradually evolved into a backbone for many organizations, and have become a topic of much concern in recent MIS studies. Among the diverse theories commonly employed to target the issue are social capital theory, social cognitive theory, and task technology fit (TTF). Social capital theory primarily addresses issues of what components constitute a social network and how they influence an individual's behavior, necessitating the introduction of social cognitive theory as the foundation for the interpretation of personal cognition. Task technology fit theory, which highlights the fit between the technological characteristics and the user's task character, is also a key factor in determining the EKR usage. This paper integrates these three theories to investigate and compare the main influences on EKR usage from personal, social and technological perspectives. Through a sampling survey of 194 EKR users, EKR self-efficacy, trust, and task technology fit are found to have substantial influences on the EKR usage. Among these three main factors, EKR self-efficacy plays the most important role in determining EKR usage.
Enhancement of the RFID security method with ownership transfer
Authors: Hsing-Bai Chen, Wei-Bin Lee, Yong-Hong Zhao, Yin-Long Chen
Venue: Proceedings of the 3rd International Conference on Ubiquitous Information Management and Communication (2009)

Radio frequency identification (RFID) is one popular technology being deployed for a variety of applications. Privacy and security issues play major roles in the success of RFID applications due to ease with masquerade, eavesdropping, etc. over the insecure channel between the tag and the reader. These security requirements are summarized: indistinguishability, forward security, ownership transfer, and resistance to replay attack and tag killing. Much research has been proposed. Except Osaka et al.'s scheme, none can meet all requirements. However, this paper introduces a new type of DoS attack which is ignored in these research studies to endanger their securities. As Osaka et al.'s scheme is superior to the others in terms of the functionalities, we take it as an example to show the possibility of the new DoS attack. A remedy is further provided to enhance the security to make the scheme more practical.
Preemptive two-level priority real-time scheduling strategy for node system in wireless sensor network
Authors: Zhao Zhibin, Li Zhuoyue, Liu Shurong
Venue: Proceedings of the 2008 International Conference on Advanced Infocomm Technology (2008)

Emerging applications such as forest fire monitoring have increasing demands on WSN to transmit data in real-time. In order to ensure real-time data transmission, it requires that the operating system of a node should schedule tasks in real-time. TinyOS is one of the most popular operation systems that support multifarious applications. However, its FIFO scheduling strategy does not guarantee requirements for hard real-time applications. A Preemptive Two-Level Priority (PTLP) Real-time Scheduling Strategy is proposed in this paper. Two tier priorities, static and dynamic, are designed and integrated in TinyOS task queue to guarantee the real-time task scheduling. We demonstrate this approach by a real-world case study: a WSN hardware node embedded with our task scheduling strategy is designed and implemented. The result demonstrates that our PTLP real-time scheduling strategy performs efficiently in terms of packet throughput and task scheduling time.
Energy-efficient geographic multicast routing for error-prone wireless sensor networks
Authors: Juan A. Sanchez, Pedro M. Ruiz
Venue: Wireless Communications Mobile Computing (2009)

Recent studies have shown that it is of paramount importance to take into account the error-prone nature of wireless links when designing routing protocols for wireless sensor networks (WSNs). We propose a new protocol called localized energy-efficient multicast algorithm (LEMA). By using a function to locally estimate the energy due to retransmissions, LEMA is able to deal with the inherent errors of WSN. This allows LEMA to find energy-efficient paths to multiple destinations. Our simulation results show that LEMA is able to outperform even well-known centralized heuristics such as minimum incremental power (MIP) and shortest path tree (SPT) based on energy, while still achieving a high packet delivery ratio (PDR). Copyright &copy; 2007 John Wiley & Sons, Ltd.
Virtual international business management learning environment for hospitality and destination management: VIRBUS: pedagogical design
Authors: Andreja Istenič Starčič
Venue: Proceedings of the 8th WSEAS international conference on Distance learning and web engineering (2008)

The paper presents pedagogical design of simulation-game-based virtual learning environment in four countries, in Finland, Slovenia, Germany and Estonia. Pedagogical design is focusing on educational changes needed in order to respond to demands of internationalization in higher and tertiary education sector. Higher education is more and more focused on approaches which shall enable students at all study levels to develop the generic and subject-specific competences so as to qualify them for obtaining access to the international work markets, where they shall prove successful in their respective activities. Changes in higher education at all the levels, systemic, organisational and individual, are required in order to put into practice the new teaching methods. Teachers are facing the need of permanently and continuously developing the teaching within the respective teaching environments.