ppxscal/embedding_network huggingface dataset:
Fair resource allocation in wireless networks using queue-length-based scheduling and congestion control
Authors: Atilla Eryilmaz, R. Srikant
Venue: IEEE/ACM Transactions on Networking (TON) (2007)

We consider the problem of allocating resources (time slots, frequency, power, etc.) at a base station to many competing flows, where each flow is intended for a different receiver. The channel conditions may be time-varying and different for different receivers. It is well-known that appropriately chosen queue-length based policies are throughput-optimal while other policies based on the estimation of channel statistics can be used to allocate resources fairly (such as proportional fairness) among competing users. In this paper, we show that a combination of queue-length-based scheduling at the base station and congestion control implemented either at the base station or at the end users can lead to fair resource allocation and queue-length stability.
Reactive-ion etching of Ge2Sb2Te5 in CF4/Ar plasma for non-volatile phase-change memories
Authors: Gaoming Feng, Bo Liu, Zhitang Song, Songlin Feng, Bomy Chen
Venue: Microelectronic Engineering (2008)

Etching of Ge"2Sb"2Te"5 (GST) is a critical step in the fabrication of chalcogenide random access memories. In this paper, the etch characteristics of GST films were studied with a CF"4/Ar gas mixture using a reactive-ion etching system. We observed a monotonic decrease in etch rate with decreasing CF"4 concentration indicating its importance in defining the material removal rate. Argon, on the other hand, plays an important role in defining the smoothness of the etched surface and sidewall edge acuity. We have studied the importance of gas mixture and RF power on the quality of the etched film. The smoothest surfaces and most vertical sidewalls were achieved using a CF"4/Ar gas mixture ratio of 10/40, a background pressure of 80mTorr, and power of 200W.
Approximate labelled subtree homeomorphism
Authors: Ron Y. Pinter, Oleg Rokhlenko, Dekel Tsur, Michal Ziv-Ukelson
Venue: Journal of Discrete Algorithms (2008)

Given two undirected trees T and P, the Subtree Homeomorphism Problem is to find whether T has a subtree t that can be transformed into P by removing entire subtrees, as well as repeatedly removing a degree-2 node and adding the edge joining its two neighbors. In this paper we extend the Subtree Homeomorphism Problem to a new optimization problem by enriching the subtree-comparison with node-to-node similarity scores. The new problem, called Approximate Labelled Subtree Homeomorphism (ALSH), is to compute the homeomorphic subtree of T which also maximizes the overall node-to-node resemblance. We describe an O(m^2n/logm+mnlogn) algorithm for solving ALSH on unordered, unrooted trees, where m and n are the number of vertices in P and T, respectively. We also give an O(mn) algorithm for rooted ordered trees and O(mnlogm) and O(mn) algorithms for unrooted cyclically ordered and unrooted linearly ordered trees, respectively.
Evaluating test adequacy coverage of high level petri nets using spin
Authors: Junhua Ding, Gonzalo Argote-Garcia, Peter J. Clarke, Xudong He
Venue: Proceedings of the 3rd international workshop on Automation of software test (2008)

How to ensure the quality of complex software systems is a grand challenge. Formal methods and software testing techniques are two major complementary approaches for software quality assurance. In this paper, we present a unique approach that uses the simulation capability of the Spin model checker to evaluate the test adequacy of high level Petri nets based on various coverage criteria. In our approach, a high level Petri net is expressed as a program in Promela, the input language for Spin, and the simulation capability of Spin is used to execute the program and evaluate different test coverage criteria for high level Petri nets. We use high level Petri nets as a concrete formal specification method to demonstrate our approach, and our results can be easily generalized to other formal models as well.
Portfolio single index (PSI) multivariate conditional and stochastic volatility models
Authors: Manabu Asai, Michael McAleer, Bernardo de Veiga
Venue: Mathematics and Computers in Simulation (2008)

The paper develops the structure of parsimonious portfolio single index (PSI) multivariate conditional and stochastic constant correlation volatility models, and methods for estimating the underlying parameters. These multivariate estimates of volatility can be used for more accurate portfolio risk management, to enable efficient forecasting of value-at-risk (VaR) thresholds, and to determine optimal Basel Accord capital charges. A parsimonious portfolio single index approach for modelling the conditional and stochastic covariance matrices of a portfolio of assets is developed, and estimation methods for the conditional and stochastic volatility models are discussed.
Similarity measures for spectral discrimination of salt-affected soils
Authors: J. Farifteh, F. van der Meer, E. J. M. Carranza
Venue: International Journal of Remote Sensing (2007)

This paper illustrates a pilot study designed to examine the spectral response of soils due to salt variations. The aim of the study includes determining whether salt-affected soils can be discriminated based on their spectral characteristics, by establishing a relationship between soil properties and soil spectra and by testing if variations in the spectra of salt-affected soil samples are statistically significant. To answer the research questions, a laboratory experiment was designed to simulate salt transport to a column of soil in order to provide direct measurements of soil spectra and soil properties when salt concentration in a soil sample changes. The measured spectra were examined by the application of spectral matching techniques to quantify the variations and ascertain a relationship that supports the spectral identification of saline soils. The Ward's grouping method was conducted as an exploratory tool to statistically create homogeneous classes among data, which were obtained from the application of the spectral matching techniques to salt affected soil spectra. A nonparametric statistical test (Mann-Whitney U-test) was used to determine whether the differences between the classes are statistically significant. The results of spectral matching techniques showed differences in absorption strength, absolute reflectance and spectral angle in the near and shortwave infrared regions. The results also showed significant correlations between soil electrical conductivity (EC) and spectral similarity measures, indicating that similarity between the samples' spectra decreases as the salt concentration in the soil increases. The generated clusters indicate two classes at the highest level, which were subdivided at the next level and further subdivided into multiple subclasses as the dissimilarity decreased. The spectral data were grouped into classes and were used to test the null hypothesis by applying the Mann-Whitney U-test. The results indicate a significance level of α
Business impact of process improvements
Authors: Frances Paulisch, Christof Ebert
Venue: Companion of the 30th international conference on Software engineering (2008)

The topic of the workshop "Business Impact of Process Improvements" is achieving tangible and sustainable business impact from process improvements. Focus is on approaches that are both practical and quantifiable. The kinds of process improvements addressed include, but are not limited to, the introduction of iterative, agile or "lean" approaches, improved requirements engineering, risk management, usage of process improvement reference frameworks, and improved quality control and assurance. Busi-ness impact should be illustrated through either increasing the value of what is delivered to the customer or reducing the cost (for example by reduction of rework effort). The audience will share experiences how to reliably set-up, measure and achieve business-oriented process improvements in order to increase return on investment in software engineering.
Building an application-aware IPsec policy system
Authors: Heng Yin, Haining Wang
Venue: IEEE/ACM Transactions on Networking (TON) (2007)

As a security mechanism at the network-layer, the IP security protocol (IPsec) has been available for years, but its usage is limited to Virtual Private Networks (VPNs). The end-to-end security services provided by IPsec have not been widely used. To bring the IPsec services into wide usage, a standard IPsec API is a potential solution. However, the realization of a user-friendly IPsec API involves many modifications on the current IPsec and Internet Key Exchange (IKE) implementations. An alternative approach is to configure application-specific IPsec policies, but the current IPsec policy system lacks the knowledge of the context of applications running at upper layers, making it infeasible to configure application-specific policies in practice. In this paper, we propose an application-aware IPsec policy system on the existing IPsec/IKE infrastructure, in which a socket monitor running in the application context reports the socket activities to the application policy engine. In turn, the engine translates the application policies into the underlying security policies, and then writes them into the IPsec Security Policy Data-base (SPD) via the existing IPsec policy management interface. We implement a prototype in Linux (Kernel 2.6) and evaluate it in our testbed. The experimental results show that the overhead of policy translation is insignificant, and the overall system performance of the enhanced IPsec is comparable to those of security mechanisms at upper layers. Configured with the application-aware IPsec policies, both secured applications at upper layers and legacy applications can transparently obtain IP security enhancements.
An Intelligent Clustering Algorithm for 3D Objects Layouts in Storage Systems
Authors: Shao-Shin Hung, Hui-Ling Lin
Venue: Proceedings of the 2008 International Conference on Multimedia and Ubiquitous Engineering (2008)

In many virtual environments (VE) applications, the size of the database is not only extremely large, it is also growing rapidly. However, little approaches for discovering object correlations in VE to improve the performance of storage systems. In this paper, we develop a class of view-based projection-generation method for mining various frequent sequential traversal patterns in the VE. The frequent sequential traversal patterns are used to predict the user navigation behavior. Furthermore, the hypergraph (HG)-based clustering scheme can help reduce disk access time with proper placement patterns into disk blocks. Finally, we have done extensive experiments to demonstrate how these proposed techniques not only significantly cut down disk access time, but also enhance the accuracy of data prefetching.
Minimal energy path planning for wireless robots
Authors: Chia Ching Ooi, Christian Schindelhauer
Venue: Proceedings of the 1st international conference on Robot communication and coordination (2007)

For the first time, the problem of optimizing energy for communication and motion is investigated. We consider a single mobile robot with continuous high bandwidth wireless communication, e.g. caused by a multimedia application like video surveillance. This robot is connected to a radio base station and moves with constant speed from a given starting point on the plane to a target point. The task is to find the best path such that the energy consumption for mobility and the communication is optimized. This is motivated by the fact that the energy consumption of radio devices increases polynomially (at least to the power of two) with the transmission distance. We introduce efficient approximation algorithms finding the optimal path given the starting point, the target point and the position of the radio stations. We exemplify the influence of the communication cost by a starting scenario with one radio station. We study the performance of the proposed algorithm in simulation, compare it with the scenario without applying our approach, and present the results.
A Location-Aware Resource Management Scheme for Ubiquitous Wireless Networks
Authors: Chenn-Jung Huang, Hong-Xin Chen, I-Fan Chen, Kai-Wen Hu
Venue: Proceedings of the 2008 International Conference on Multimedia and Ubiquitous Engineering (2008)

As mobile wireless networks increase in popularity and pervasiveness, using internet ubiquitously isn’t a dream. The future Wireless Internet is expected to consist of different types of wireless network with different coverage ranges. The integration of Wireless Metropolitan Area Network (WMAN) and Wireless Local Area Network (WLAN) technologies seems to be a feasible option for better and cheaper wireless coverage extension. This hybrid network can take advantage of the benefits of both technologies to provide ubiquitous services with high quality of service (QoS). In order to improve the bandwidth utilization and reduce the interference in heterogeneous WMAN/WLAN networks, this work applies genetic algorithm-based bandwidth allocation techniques along with space division multiple access (SDMA) to manage the precious bandwidth resource in the heterogeneous wireless networks. The simulation results show that our scheme is effective in terms of performance metrics, including dropping probability of handoff calls, new call blocking probability, and bandwidth utilization.
Windows Registry and Hiding Suspects' Secret in Registry
Authors: Youngsoo Kim, Dowon Hong
Venue: Proceedings of the 2008 International Conference on Information Security and Assurance (isa 2008) (2008)

Windows registry, a central repository for configuration data, should be investigated for obtaining forensic evidences, since it contains lots of information that are of potential evidential value. Using some forensic tools, forensic examiners can investigate values of windows registry and get information can be forensic evidences. However, since windows registry contains huge amount of values and these values can be modified by users, suspect can hide his secret like password in registry values. In this paper, we discuss the basics of Windows XP registry and extract some registry entries related to forensic analysis. Finally, we show that some countermeasures are needed, listing up consideration items for hiding secrets in registry as suspect’s viewpoint.
The Beta-Jacobi Matrix Model, the CS Decomposition, and Generalized Singular Value Problems
Authors: Alan Edelman, Brian D. Sutton
Venue: Foundations of Computational Mathematics (2008)

We provide a solution to the &#x03b2;-Jacobi matrix model problem posed by Dumitriu and the first author. The random matrix distribution introduced here, called a matrix model, is related to the model of Killip and Nenciu, but the development is quite different. We start by introducing a new matrix decomposition and an algorithm for computing this decomposition. Then we run the algorithm on a Haar-distributed random matrix to produce the &#x03b2;-Jacobi matrix model. The Jacobi ensemble on ${\Bbb R}^{n}$, parametrized by &#x03b2; > 0, a > -1,and b > -1, is the probability distribution whose density is proportional to $\prod_{i}\lambda_{i}^{({\beta}/{2})(a+1)-1}(1-\lambda_{i})^{({\beta}/{2})(b+1)-1}\prod_{i<j}|\lambda_{i}-\lambda_{j}|^{\beta}$. The matrix model introduced in this paper is a probability distribution on structured orthogonal matrices. If J is a random matrix drawnfrom this distribution, then a CS decomposition can be taken, $$J=\left[\begin{array}{@{}cc@{}} U_{1}\\ & U_{2}\end{array}\right]\left[\begin{array}{@{}rc@{}} C & S\\-S & C\end{array}\right]\left[\begin{array}{@{}cc@{}} V_{1}\\ & V_{2}\end{array}\right]^{T}$$, in which C and S are diagonal matrices with entries in [0,1]. J is designed so that the diagonal entries of C, squared, follow the law of the Jacobi ensemble. When &#x03b2; = 1 (resp., &#x03b2; = 2), the matrix model is derived by running a numerically inspired algorithm on a Haar-distributed random matrix from the orthogonal (resp., unitary) group. Hence, the matrix model generalizes certain features of the orthogonal and unitary groups beyond &#x03b2; = 1 and &#x03b2; = 2 to general &#x03b2; > 0. Observing a connection between Haar measure on the orthogonal (resp., unitary) group and pairs of real (resp., complex) Gaussian matrices, we find a direct connection between multivariate analysis of variance (MANOVA) and the new matrix model.
Power laws in software
Authors: Panagiotis Louridas, Diomidis Spinellis, Vasileios Vlachos
Venue: ACM Transactions on Software Engineering and Methodology (TOSEM) (2008)

A single statistical framework, comprising power law distributions and scale-free networks, seems to fit a wide variety of phenomena. There is evidence that power laws appear in software at the class and function level. We show that distributions with long, fat tails in software are much more pervasive than previously established, appearing at various levels of abstraction, in diverse systems and languages. The implications of this phenomenon cover various aspects of software engineering research and practice.
Parallelizing dynamic information flow tracking
Authors: Olatunji Ruwase, Phillip B. Gibbons, Todd C. Mowry, Vijaya Ramachandran, Shimin Chen, Michael Kozuch, Michael Ryan
Venue: Proceedings of the twentieth annual symposium on Parallelism in algorithms and architectures (2008)

Dynamic information flow tracking (DIFT) is an important tool for detecting common security attacks and memory bugs. A DIFT tool tracks the flow of information through a monitored program's registers and memory locations as the program executes, detecting and containing/fixing problems on-the-fly. Unfortunately, sequential DIFT tools are quite slow, and DIFT is quite challenging to parallelize. In this paper, we present a new approach to parallelizing DIFT-like functionality. Extending our recent work on accelerating sequential DIFT, we consider a variant of DIFT that tracks the information flow only through unary operations relaxed DIFT, and yet makes sense for detecting security attacks and memory bugs. We present a parallel algorithm for relaxed DIFT, based on symbolic inheritance tracking, which achieves linear speed-up asymptotically. Moreover, we describe techniques for reducing the constant factors, so that speed-ups can be obtained even with just a few processors. We implemented the algorithm in the context of a Log-Based Architectures (LBA) system, which provides hardware support for logging a program trace and delivering it to other (monitoring) processors. Our simulation results on SPEC benchmarks and a video player show that our parallel relaxed DIFT reduces the overhead to as low as 1.2X using 9 monitoring cores on a 16-core chip multiprocessor.
The application of knowledge-sharing workspace paradigm for software architecture processes
Authors: Muhammad Ali-Babar
Venue: Proceedings of the 3rd international workshop on Sharing and reusing architectural knowledge (2008)

Management of architectural knowledge is vital for improving an organisation's capabilities in software architecture. Recently, there have been many efforts to develop various kinds of tools for managing architectural knowledge. However, most of these efforts overlook the fact that most of the working teams in today's organisations are distributed. This paper proposes the application of electronic workspace paradigm for capturing and sharing knowledge to support the software architecture processes.
The anatomy of prototypes: Prototypes as filters, prototypes as manifestations of design ideas
Authors: Youn-Kyung Lim, Erik Stolterman, Josh Tenenberg
Venue: ACM Transactions on Computer-Human Interaction (TOCHI) (2008)

The role of prototypes is well established in the field of HCI and Design. A lack of knowledge, however, about the fundamental nature of prototypes still exists. Researchers have attempted to identify different types of prototypes, such as low- vs. high-fidelity prototypes, but these attempts have centered on evaluation rather than support of design exploration. There have also been efforts to provide new ways of thinking about the activity of using prototypes, such as experience prototyping and paper prototyping, but these efforts do not provide a discourse for understanding fundamental characteristics of prototypes. In this article, we propose an anatomy of prototypes as a framework for prototype conceptualization. We view prototypes not only in their role in evaluation but also in their generative role in enabling designers to reflect on their design activities in exploring a design space. We base this framework on the findings of two case studies that reveal two key dimensions: prototypes as filters and prototypes as manifestations. We explain why these two dimensions are important and how this conceptual framework can benefit our field by establishing more solid and systematic knowledge about prototypes and prototyping.
An empirical examination of factors contributing to the creation of successful e-learning environments
Authors: Richard D. Johnson, Steven Hornik, Eduardo Salas
Venue: International Journal of Human-Computer Studies (2008)

Although existing models of e-learning effectiveness in information systems (IS) have increased our understanding of how technology can support and enhance learning, most of our models do not take into account the importance of social presence. Thus, this study extends previous research by developing a model of e-learning effectiveness which adds social presence to other oft studied variables including application-specific computer self-efficacy (AS-CSE), perceived usefulness, course interaction, and e-learning effectiveness. Using data from 345 individuals, this model was validated through a field study in an introductory IS survey course. Results indicate that AS-CSE and perceived usefulness were related to course performance, course satisfaction, and course instrumentality. In addition, course interaction was related to course performance and satisfaction. Finally, social presence was related to course satisfaction and course instrumentality. Implications for research and practice are discussed.
Technology scruples: why intimidation will not save the recording industry and how enchantment might
Authors: Mark Blythe, Peter Wright
Venue: Personal and Ubiquitous Computing (2008)

While the recording industry continues to lobby for increasingly draconian laws to protect their interests, users of digital technology continue to share files and copy protected music. This paper considers the ethics of copying and argues that legal measures are unlikely to solve the music industry's problems in the age of digital reproduction. It begins with a review of the legal arguments around copyright legislation and notes that the law is currently unclear and contested. Adapting the game "scruples" to questions of what is and is not considered theft, a qualitative study reflects on the ways that ethical positions around new media are reached and articulated. The findings relate ethical positions constructed around notions of resistance, intangibility and identity. It is argued that the global online population cannot be policed without consent and that mechanics of artist reimbursement must be developed that account for consumers' technology scruples. File sharing is then considered not as a legal problem but as a design challenge and a strategy of enchantment is suggested. The design concept of a digital music box is outlined to illustrate strategies of enchantment rather than litigation and intimidation.