ppxscal/embedding_network huggingface dataset:
Merrimac: high-performance and highly-efficient scientific computing with streams
Authors: William J. Dally
Venue:  (2007)

Advances in VLSI technology have made the raw ingredients for computation plentiful. Large numbers of fast functional units and large amounts of memory and bandwidth can be made efficient in terms of chip area, cost, and energy, however, high-performance computers realize only a small fraction of VLSI's potential. This dissertation describes the Merrimac streaming supercomputer architecture and system. Merrimac has an integrated view of the applications, software system, compiler, and architecture. We will show how this approach leads to over an order of magnitude gains in performance per unit cost, unit power, and unit floor-space for scientific applications when compared to common scientific computers designed around clusters of commodity general-purpose processors. The dissertation discusses Merrimac's stream architecture, the mapping of scientific codes to effectively run on the stream architecture, and system issues in the Merrimac supercomputer.The stream architecture is designed to take advantage of the properties of modern semiconductor technology---very high bandwidth over short distances and very high transistor counts, but limited global on-chip and off-chip bandwidths---and match them with the characteristics of scientific codes---large amounts of parallelism and access locality. Organizing the computation into streams and exploiting the resulting locality using a register hierarchy enables a stream architecture to reduce the memory bandwidth required by representative computations by an order of magnitude or more. Hence a processing node with a fixed memory bandwidth (which is expensive) can support an order of magnitude more arithmetic units (which are inexpensive). Because each node has much greater performance (128 double-precision GFLOP/s) than a conventional microprocessor, a streaming supercomputer can achieve a given level of performance with fewer nodes, reducing costs, simplifying system management, and increasing reliability.
Existence and uniqueness of periodic solutions for a kind of Liénard equation with two deviating arguments
Authors: Qiyuan Zhou, Fei Long
Venue: Journal of Computational and Applied Mathematics (2007)

In this paper, a kind of Lienard equation with two deviating arguments of the formx^''(t)+f(x(t))x^'(t)+g"1(t,x(t-@t"1(t)))+g"2(t,x(t-@t"2(t)))=p(t)is considered. We derive some new sufficient conditions for checking uniqueness of T-periodic solutions of this equation. By using coincidence degree theory, we also establish some new results on the existence and uniqueness of T-periodic solutions for this equation, which are new and complement previously known results.
In the News
Authors: Laurianne McLaughlin, Jan Krikke
Venue: IEEE Intelligent Systems (2007)

The first news story, "AI Fuels Better Video Search," looks at how researchers are using AI methods to improve the accuracy of video search results. The second news story, "The Challenge of Go," reports on current attempts to develop computer programs that play Go.
Evaluating digital video recorder systems using analytic hierarchy and analytic network processes
Authors: Che-Wei Chang, Cheng-Ru Wu, Chin-Tsai Lin, Hung-Lung Lin
Venue: Information Sciences: an International Journal (2007)

Digital video recorder (DVR) systems are novel security products with significant potential for application in the surveillance market, which, like many other areas of security technology, is changing quickly. Consumer demand and procuring budgets of system development firms are increasingly being emphasized, motivating upgrades to system quality. Digital surveillance systems include both hardware and software. Procurers have difficulty complying with these standards due to the wide gap between the descriptions in the standards and interpretations of evaluations of digital video recorder systems such as the functions of channel, recording, playback and display, communication and remote transmission. A case study compares the analytic hierarchy process (AHP) and analytic network process (ANP) decision models, and the comparison results indicate that interdependencies can affect real decisions. For network-like decision models (i.e., decision problems that can be structured in a network model form), ANP represents an effective tool for providing an accurate solution for administrators or managers of this case.
Spatial skills and navigation of source code
Authors: Sue Jane Jones, Gary E. Burnett
Venue: ACM SIGCSE Bulletin (2007)

Learning to program is a difficult process, and students that perform well in other subjects may not produce comparable results in programming. Evidence suggests that some programmers are inherently more skilled than others, and one individual difference that has been shown to be important is spatial ability. This cognitive characteristic is implicated in successful real-world navigation. It is also important for navigating within hypertext, and there is a growing recognition that it has a part to play in program comprehension and development, with navigation of source code considered similar to navigating in the real world. Little research has been carried out to study the navigational patterns of programmers with differing spatial skills. In this study, 24 students enrolled on a Masters in IT course at a University in the UK were given a code comprehension exercise. Various measures were made of time taken and movement around the code. Those with high spatial ability completed the task in shorter time, spent less time searching around deciding where to go next, and jumped more frequently within and between class files. Strong relations were also found between spatial ability and results in programming modules, with much weaker relations with non-programming modules. This paper discusses the implications of these results in relation to the accessibility of programming to learners with low spatial ability.
Exploiting the internet inter-ORB protocol interface to provide CORBA with fault tolerance
Authors: P. Narasimhan, L. E. Moser, P. M. Melliar-Smith
Venue: Proceedings of the 3rd conference on USENIX Conference on Object-Oriented Technologies (COOTS) - Volume 3 (1997)

The Eternal system is a CORBA 2.0-compliant system that provides, in addition to the location transparency and the interoperability inherent in the CORBA standard, support for replicated objects and thus fault tolerance. Eternal exploits the Internet Inter-ORB Protocol (IIOP) interface to "attach" itself transparently to objects operating over a commercial CORBA Object Request Broker (ORB). The Eternal Interceptor captures the IIOP system calls of the objects, and the Eternal Replication Manager maps these system calls onto a reliable totally ordered multicast group communication system. No modification to the internal structure of the ORB is necessary, and fault tolerance is provided in a manner that is transparent to both the application and the ORB.
Multiclass classifiers based on dimension reduction with generalized LDA
Authors: Hyunsoo Kim, Barry L. Drake, Haesun Park
Venue: Pattern Recognition (2007)

Linear discriminant analysis (LDA) has been widely used for dimension reduction of data sets with multiple classes. The LDA has been recently extended to various generalized LDA methods that are applicable regardless of the relative sizes between the data dimension and the number of data items. In this paper, we propose several multiclass classifiers based on generalized LDA (GLDA) algorithms, taking advantage of the dimension reducing transformation matrix without requiring additional training or parameter optimization. A marginal linear discriminant classifier (MLDC), a Bayesian linear discriminant classifier (BLDC), and a one-dimensional BLDC are introduced for multiclass classification. Our experimental results illustrate that these classifiers produce higher ten-fold cross validation accuracy than kNN and centroid-based classifiers in the reduced dimensional space obtained from GLDA.
I/O processing in a virtualized platform: a simulation-driven approach
Authors: Vineet Chadha, Ramesh Illiikkal, Ravi Iyer, Jaideep Moses, Donald Newell, Renato J. Figueiredo
Venue: Proceedings of the 3rd international conference on Virtual execution environments (2007)

Virtualization provides levels of execution isolation and service partition that are desirable in many usage scenarios, but its associated overheads are a major impediment for wide deployment of virtualized environments. While the virtualization cost depends heavily on workloads, it has been demonstrated that the overhead is much higher with I/O intensive workloads compared to those which are compute-intensive. Unfortunately, the architectural reasons behind the I/O performance overheads are not well understood. Early research in characterizing these penalties has shown that cache misses and TLB related overheads contribute to most of I/O virtualization cost. While most of these evaluations are done using measurements, in this paper we present an execution-driven simulation based analysis methodology with symbol annotation as a means of evaluating the performance of virtualized workloads. This methodology provides detailed information at the architectural level (with a focus on cache and TLB) and allows designers to evaluate potential hardware enhancements to reduce virtualization overhead. We apply this methodology to study the network I/O performance of Xen (as a case study) in a full system simulation environment, using detailed cache and TLB models to profile and characterize software and hardware hotspots. By applying symbol annotation to the instruction flow reported by the execution driven simulator we derive function level call flow information. We follow the anatomy of I/O processing in a virtualized platform for network transmit and receive scenarios and demonstrate the impact of cache scaling and TLB size scaling on performance.
Using Model-Driven Development in Time-Constrained Course Projects
Authors: Wilson Padua
Venue: Proceedings of the 20th Conference on Software Engineering Education & Training (2007)

Educational software development processes, used in course projects, must exercise practices and artifacts comparable to similar industry-level processes, while achieving acceptable productivity and quality, and, at the same time, complying with constraints on available student time. Here, we discuss our experience with a specific model-driven development process, applied in a time-constrained software engineering course. The course projects are developed in iterations, each delivering a subset of the product functions. These, specified as use cases, undergo a sequence of model transformations, until they become tested code. Transformation steps are verified using standardized quality gates (inspections, tests, and audits), which serve three purposes: teaching verification, validation and quality assurance; helping to assess and grade projects; and providing feedback for process improvement. Size, effort and defect data is recorded in standardized reports. Collected data show that the quality gates proved effective to ensure compliance with the prescribed process, and that using a balanced reusable framework is necessary to achieve satisfactory productivity and quality.
A Natural Family of Flag Matroids
Authors: Anna de Mier
Venue: SIAM Journal on Discrete Mathematics (2007)

A flag matroid can be viewed as a chain of matroids linked by quotients. Flag matroids, of which relatively few interesting families have previously been known, are a particular class of Coxeter matroids. In this paper we give a family of flag matroids arising from an enumeration problem that is a generalization of the tennis ball problem. These flag matroids can also be defined in terms of lattice paths, and they provide a generalization of the lattice path matroids of [J. Bonin, A. de Mier, and M. Noy, J. Combin. Theory Ser. A, 104 (2003), pp. 63-94].
NeoWebScript: enabling webpages with active content using Tcl
Authors: Karl Lehenbauer
Venue: Proceedings of the 6th conference on Annual Tcl/Tk Workshop, 1998 - Volume 6 (1998)

NeoWebScript marries the world's most popular web-server, Apache, with the Tcl programming language to create a secure, efficient, server-side scripting language that gives webpage developers simple-yet-powerful tools for creating and serving webpages with active content. The ability to embed NeoWebScript code into existing webpages, without requiring a URL name change, leverages work done with webpage creation tools such as Netscape Communicator and Net Objects Fusion, while not disturbing links from remote sites and search engines. A mature application, NeoWebScript-equipped web-servers are currently in production on the Internet, serving real-world loads of millions of webpage "hits" per day. This paper describes the driving forces behind the creation of NeoWebScript, and how those forces shaped its design and evolution into its current-day form. NeoWebScript's software architecture is described, and its capabilities are demonstrated using numerous examples, including webpage "visitor counters", rotating banner ads, queuing email, posting news, storing form submissions into Berkeley-style "dbopen" databases, and creating graphical images on the fly. Finally, NeoWebScript's current status is summarized, our near-term plans are detailed, and conclusions are drawn.
A Quantitative Evaluation of Video-based 3D Person Tracking
Authors: A. O. Balan, L. Sigal, M. J. Black
Venue: Proceedings of the 14th International Conference on Computer Communications and Networks (2005)

The Bayesian estimation of 3D human motion from video sequences is quantitatively evaluated using synchronized, multi-camera, calibrated video and 3D ground truth poses acquired with a commercial motion capture system. While many methods for human pose estimation and tracking have been proposed, to date there has been no quantitative comparison. Our goal is to evaluate how different design choices influence tracking performance. Toward that end, we independently implemented two fairly standard Bayesian person trackers using two variants of particle filtering and propose an evaluation measure appropriate for assessing the quality of probabilistic tracking methods. In the Bayesian framework we compare various image likelihood functions and prior models of human motion that have been proposed in the literature. Our results suggest that in constrained laboratory environments, current methods perform quite well. Multiple cameras and background subtraction, however, are required to achieve reliable tracking suggesting that many current methods may be inappropriate in more natural settings. We discuss the implications of the study and the directions for future research that it entails.
Binary differential evolution for the unit commitment problem
Authors: Ali Keles
Venue: Proceedings of the 2007 GECCO conference companion on Genetic and evolutionary computation (2007)

The Unit Commitment Problem (UCP) is the task of finding an optimal turn on and turn off schedule for a group of power generation units over a given time horizon to minimize operation costs while satisfying the hourly power demand constraints. Various approaches exist in the literature for solving this problem. This paper reports the results of experiments performed on a series of the UCP test data using the binary differential evolution approach combined with a simple local search mechanism. In the future stages of the project, the algorithm will be applied to solve the UCP for the Turkish interconnected power system.
The Commons as New Economy & What This Means for Research
Authors: Richard P. Gabriel
Venue: Proceedings of the First International Workshop on Emerging Trends in FLOSS Research and Development (2007)

Suppose the entire social and commercial fabric supporting the creation of software is changing--changing by becoming completely a commons and thereby dropping dramatically in cost. How would the world change and how would we recognize the changes? Software would not be continually recreated by different organizations, so the global "efficiency" of software production would increase dramatically; therefore it would be possible to create value without waste, experimentation and risk-taking would become affordable--and probably necessary because firms could not charge for their duplication of infrastructure--, and the size and complexity of built systems would increase dramatically, perhaps beyond human comprehension. As important or more so, the activities of creating software would become the provenance of people, organizations, and disciplines who today are mostly considered consumers of software--there would, in a very real sense, be only a single software system in existence, continually growing; it would be an ecology husbanded along by economists, sociologists, governments, clubs, communities, and herds of disciplines. New business models would be developed, perhaps at an alarming rate. How should we design our research to observe and understand this change? There is some evidence the change is underway, as the result of the adoption of open source by companies who are not merely appreciative receivers of gifts from the evangelizers of open source, but who are clever thieves re-purposing the ideas and making up new ones of their own.
Equational Cryptographic Reasoning in the Maude-NRL Protocol Analyzer
Authors: Santiago Escobar, Catherine Meadows, José Meseguer
Venue: Electronic Notes in Theoretical Computer Science (ENTCS) (2007)

The NRL Protocol Analyzer (NPA) is a tool for the formal specification and analysis of cryptographic protocols that has been used with great effect on a number of complex real-life protocols. One of the most interesting of its features is that it can be used to reason about security in face of attempted attacks on low-level algebraic properties of the functions used in a protocol. Recently, we have given for the first time a precise formal specification of the main features of the NPA inference system: its grammar-based techniques for (co-)invariant generation and its backwards narrowing reachability analysis method; both implemented in Maude as the Maude-NPA tool. This formal specification is given within the well-known rewriting framework so that the inference system is specified as a set of rewrite rules modulo an equational theory describing the behavior of the cryptographic symbols involved. This paper gives a high-level overview of the Maude-NPA tool and illustrates how it supports equational reasoning about properties of the underlying cryptographic infrastructure by means of a simple, yet nontrivial, example of an attack whose discovery essentially requires equational reasoning. It also shows how rule-based programming languages such as Maude and complex narrowing strategies are useful to model, analyze, and verify protocols.
A machine-independent DMA framework for NetBSD
Authors: Jason R. Thorpe
Venue: Proceedings of the annual conference on USENIX Annual Technical Conference (1998)

One of the challenges in implementing a portable kernel is finding good abstractions for semantically-similar operations which often have very machine-dependent implementations. This is especially important on modern machines which share common architectural features, e.g. the PCI bus. This paper describes why a machine-independent DMA mapping abstraction is needed, the design considerations for such an abstraction, and the implementation of this abstraction in the NetBSD/alpha and NetBSD/i386 kernels.
Equilibria for networks with malicious users
Authors: George Karakostas, Anastasios Viglas
Venue: Mathematical Programming: Series A and B (2007)

We consider the problem of characterizing user equilibria and optimal solutions for selfish routing in a given network. We extend the known models by considering malicious behavior. While selfish users follow a strategy that minimizes their individual cost, a malicious user will use his flow through the network in an effort to cause the maximum possible damage to the overall cost. We define a generalized model, present characterizations of flows at equilibrium and prove bounds for the ratio of the social cost of a flow at equilibrium over the cost when centralized coordination among users is allowed.
Access Control Model for Web Services with Attribute Disclosure Restriction
Authors: Vipin Singh Mewar, Subhendu Aich, Shamik Sural
Venue: Proceedings of the The Second International Conference on Availability, Reliability and Security (2007)

Web service is a programmable interface accessible through a network. In this paper we focus on the scenario in which different organizations use web services to collaborate, share knowledge, integrate services and for providing value added services to customers. As a test case, we consider health care application in which different hospitals can give various types of services to other hospitals. We find Attribute Based Access Control (ABAC) model to be quite suitable for access control in web services. However, there is a need to enforce user's security policy to decide only which attributes should be disclosed so that users can reveal their attributes to service providers according to their need. We extend the ABAC model with user attribute disclosure restriction and propose a framework for defining and applying security policies.
Interchanging discrete event simulation process interaction models using the web ontology language---owl
Authors: Jose Sepulveda
Venue:  (2006)

Discrete event simulation development requires significant investments in time and resources. Descriptions of discrete event simulation models are associated with world views, including the process interaction orientation. Historically, these models have been encoded using high-level programming languages or special purpose, typically vendor-specific, simulation languages. These approaches complicate simulation model reuse and interchange. The current document-centric World Wide Web is evolving into a Semantic Web that communicates information using ontologies. The Web Ontology Language---OWL, was used to encode a Process Interaction Modeling Ontology for Discrete Event Simulations (PIMODES). The PIMODES ontology was developed using ontology engineering processes. Software was developed to demonstrate the feasibility of interchanging models from commercial simulation packages using PIMODES as an intermediate representation. The purpose of PIMODES is to provide a vendor-neutral open representation to support model interchange. Model interchange enables reuse and provides an opportunity to improve simulation quality, reduce development costs, and reduce development times.
On-line EEG classification and sleep spindles detection using an adaptive recursive bandpass filter
Authors: R. R. Gharieb
Venue: Proceedings of the Acoustics, Speech, and Signal Processing, 200. on IEEE International Conference - Volume 02 (2001)

This paper presents a novel adaptive filtering approach for the classification and tracking of the electroencephalogram (EEG) waves. In this approach, an adaptive recursive bandpass filter is employed for estimating and tracking the center frequency associated with each EEG wave. The main advantage inherent in the approach is that the employed adaptive filter only requires one coefficient to be updated. This coefficient represents an efficient distinct feature for each EEG specific wave and its time function reflects the nonstationarity of the EEG signal. Extensive simulations for synthetic and real world EEG data for the detection of sleep spindles show the effectiveness and usefulness of the presented approach.