ppxscal/embedding_network huggingface dataset:
Virtual community prescence awareness
Authors: David G. Boyer, Mark J. Handel, James Herbsleb
Venue: ACM SIGGROUP Bulletin (1998)

The goal of the work presented in this paper is to identify ways to improve the speed, efficiency and quality with which a distributed development team develops their product and delivers it to market. We are working closely with a distributed product team at Lucent Technologies in order to ensure that our efforts are based on the needs of an existing distributed organization. Interviews have been conducted with members of this organization which have revealed a number of problems which affect distributed groups. Some of the problems identified were: the lack of tools to share data during meetings, insufficient organizational information, lack of knowledge concerning who was responsible for each module of the system, lack of any informal, unplanned, encounters/meetings between the distributed sites, and lack of presence information; e.g. in today or on holiday, for distant colleagues.The focus of the work presented in this paper is to provide tools, which allow this virtual community to have more informal/impromptu encounters based on knowledge of distant colleagues' presence. We believe that this will help the distributed group begin to feel more like a team, and will substantially lower the cost of initiating communication with someone at a remote site. Currently, it is difficult and time consuming to get hold of someone because there is no way to tell if they are available, or if they are momentarily away from their desks, or in the midst of a crisis, or away on vacation, or if the other site is closed for a holiday. For co-located team members, this sort of information is provided by local knowledge and by signals such as closed doors, so it is much easier, and takes much less time, to contact a colleague. Informal communication plays a critical role in project coordination, and facilitating informal communication across sites can be expected to significantly reduce the problems of multi-site development.The tools have two main thrusts -presence detection and communications. Presence cues are primarily detected by computer or telephony activity, as well as information provided directly by the user. Communications capabilities range from text chat, audio conferencing to video conferencing. In addition, these tools attempt to use information stored in disparate places, including the corporate intranet and the software configuration management system. It is hoped that these links to various forms of institutional memory will help to provide not just information about an individual's presence and location, but help to suggest which individual to contact for answers or help.
Micro-CT imaging of structure-to-function relationship of bone microstructure and associated vascular involvement
Authors: Erik L. Ritman, Mark E. Bolander, Lorraine A. Fitzpatrick, Russell T. Turner
Venue: Technology and Health Care (1998)

We are exploring methods of quantitating the 3D microstructure of bone in a way that will provide quantitative information about the functional status of the bone. The basic strategy is to image the spatial distribution of a selected, local, marker of function (e.g., material properties or new bone formation) and relate this to the simultaneously imaged 3D anatomic microstructure. Many of these approaches are extensions of well-established 2D imaging techniques (e.g., use of fluorophores and autoradiography) to 3D micro-CT. Local stresses throughout the microstructure can be estimated from the 3D geometry (and change in that geometry in response to stress applied to the outside of the bones) and correlated to the local function. In addition to study of bone, we are also exploring calcification of arterial walls, both within the bone and outside the bone, such as coronary arteries. Arterial calcification in ovariectomised rats has been observed.
Fast Online Q(&lambda;)
Authors: Marco Wiering, Jürgen Schmidhuber
Venue: Machine Learning (1998)

Q(&lambda;)-learning uses TD(&lambda;)-methods to accelerate Q-learning. The update complexity of previous online Q(&lambda;) implementations based on lookup tables is bounded by the size of the state/action space. Our faster algorithm&lsquo;s update complexity is bounded by the number of actions. The method is based on the observation that Q-value updates may be postponed until they are needed.
A data model and data structures for moving objects databases
Authors: Luca Forlizzi, Ralf Hartmut Güting, Enrico Nardelli, Markus Schneider
Venue: ACM SIGMOD Record (2000)

We consider spatio-temporal databases supporting spatial objects with continuously changing position and extent, termed moving objects databases. We formally define a data model for such databases that includes complex evolving spatial structures such as line networks or multi-component regions with holes. The data model is given as a collection of data types and operations which can be plugged as attribute types into any DBMS data model (e.g. relational, or object-oriented) to obtain a complete model and query language. A particular novel concept is the sliced representation which represents a temporal development as a set of units, where unit types for spatial and other data types represent certain &ldquo;simple&rdquo; functions of time. We also show how the model can be mapped into concrete physical data structures in a DBMS environment.
The visible Web browser
Authors: Atticus Gifford, Benjamin J. Menasha, David Finkel
Venue: Proceedings of the 4th annual SIGCSE/SIGCUE ITiCSE conference on Innovation and technology in computer science education (1999)

As an aid to the study of the World-Wide Web, we have developed a software application that allows a user to observe the messages passed between a Web browser and a Web server. The application is based on the Mozilla Web Browser, and displays the HTTP headers sent and received by the browser. The program could be used by students in courses studying the Web, by researchers interested in the behavior of Web servers, and by developers to debug Web-based applications.
Adaptive Linear Quadratic Gaussian Control: The Cost-Biased Approach Revisited
Authors: M. C. Campi, P. R. Kumar
Venue: SIAM Journal on Control and Optimization (1998)

In adaptive control, a standard approach is to resort to the so-called certainty equivalence principle which consists of generating some standard parameter estimate and then using it in the control law as if it were the true parameter. As a consequence of this philosophy, the estimation problem is decoupled from the control problem and this substantially simplifies the corresponding adaptive control scheme. On the other hand, the complete absence of dual properties makes certainty equivalent controllers run into an identifiability problem which generally leads to a strictly suboptimal performance.In this paper, we introduce a cost-biased parameter estimator to overcome this difficulty. This estimator is applied to a linear quadratic Gaussian controller. The corresponding adaptive scheme is proven to be stable and optimal when the unknown system parameter lies in an infinite, yet compact, parameter set.
Shrinking the warehouse update Window
Authors: Wilburt Juan Labio, Ramana Yerneni, Hector Garcia-Molina
Venue: ACM SIGMOD Record (1999)

Warehouse views need to be updated when source data changes. Due to the constantly increasing size of warehouses and the rapid rates of change, there is increasing pressure to reduce the time taken for updating the warehouse views. In this paper we focus on reducing this &ldquo;update window&rdquo; by minimizing the work required to compute and install a batch of updates. Various strategies have been proposed in the literature for updating a single warehouse view. These algorithms typically cannot be extended to come up with good strategies for updating an entire set of views. We develop an efficient algorithm that selects an optimal update strategy for any single warehouse view. Based on this algorithm, we develop an algorithm for selecting strategies to update a set of views. The performance of these algorithms is studied with experiments involving warehouse views based on TPC-D queries.
Making abstract interpretations complete
Authors: Roberto Giacobazzi, Francesco Ranzato, Francesca Scozzari
Venue: Journal of the ACM (JACM) (2000)

Completeness is an ideal, although uncommon, feature of abstract interpretations, formalizing the intuition that, relatively to the properties encoded by the underlying abstract domains, there is no loss of information accumulated in abstract computations. Thus, complete abstract interpretations can be rightly understood as optimal. We deal with both pointwise completeness, involving generic semantic operations, and (least) fixpoint completeness. Completeness and fixpoint completeness are shown to be properties that depend on the underlying abstract domains only. Our primary goal is then to solve the problem of making abstract interpretations complete by minimally extending or restricting the underlying abstract domains. Under the weak and reasonable hypothesis of dealing with continuous semantic operations, we provide constructive characterizations for the least complete extensions and the greatest complete restrictions of abstract domains. As far as fixpoint completeness is concerned, for merely monotone semantic operators, the greatest restrictions of abstract domains are constructively characterized, while it is shown that the existence of least extensions of abstract domains cannot be, in general, guaranteed, even under strong hypotheses. These methodologies, which in finite settings give rise to effective algorithms, provide advanced formal tools for manipulating and comparing abstract interpretations, useful both in static program analysis and in semantics design. A number of examples illustrating these techniques are given.
A Truncated RQ Iteration for Large Scale Eigenvalue Calculations
Authors: D. C. Sorensen, C. Yang
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

We introduce a new Krylov subspace iteration for large scale eigenvalue problems that is able to accelerate the convergence through an inexact (iterative) solution to a shift-invert equation. The method also takes full advantage of exact solutions when they can be obtained with sparse direct method. We call this new iteration the truncated RQ (TRQ) iteration. It is based upon a recursion that develops in the leading k columns of the implicitly shifted RQ iteration for dense matrices. Inverse-iteration-like convergence to a partial Schur decomposition occurs in the leading k columns of the updated basis vectors and Hessenberg matrices. The TRQ iteration is competitive with the rational Krylov method of Ruhe when the shift-invert equations can be solved directly and with the Jacobi--Davidson method of Sleijpen and Van der Vorst when these equations are solved inexactly with a preconditioned iterative method. The TRQ iteration is related to both of these but is derived directly from the RQ iteration and thus inherits the convergence properties of that method. Existing RQ deflation strategies may be employed directly in the TRQ iteration.
Metrics and Criteria for Quality Assessment of Testable Hw/Sw Systems Architectures
Authors: Octávio P. Dias, Isabel C. Teixeira, J. Paulo Teixeira
Venue: Journal of Electronic Testing: Theory and Applications (1999)

The purpose of this paper is to present a novel methodology for assessing the quality of architecture solutions of hw/sw systems, with particular emphasis on testability. Criteria and metrics for quality assessment are proposed and used to assist the design team in selecting a &lsquo;best-fitted&rsquo; architecture that satisfies not only functional requirements, but also test requirements. The methodology makes use of object-oriented modeling techniques. Near-optimum clustering of methods and attributes into objects is carried out, in such a way that objects with moderate complexity, low coupling and high functional autonomy, result. The main features of the methodology are ascertained through a case study.
Design and Implementation of Efficient Message Scheduling for Controller Area Network
Authors: Khawar M. Zuberi, Kang G. Shin
Venue: IEEE Transactions on Computers (2000)

The Controller Area Network (CAN) is being widely used in real-time control applications such as automobiles, aircraft, and automated factories. In this paper, we present the mixed traffic scheduler (MTS) for CAN, which provides higher schedulability than fixed-priority schemes like deadline-monotonic (DM) while incurring less overhead than dynamic earliest-deadline (ED) scheduling. We also describe how MTS can be implemented on existing CAN network adapters such as Motorola's TouCAN. In previous work [1], [2], we had shown MTS to be far superior to DM in schedulability performance. In this paper, we present implementation overhead measurements showing that processing needed to support MTS consumes only about 5 to 6 percent of CPU time. Considering its schedulability advantage, this makes MTS ideal for use in control applications.
Solving Irregular Econometric and Mathematical Optimization Problems with a Genetic Hybrid Algorithm
Authors: Ralf Östermark
Venue: Computational Economics (1999)

In the present paper we apply a new Genetic Hybrid Algorithm (GHA) to globally minimize a representative set of ill-conditioned econometric/mathematical functions. The genetic algorithm was specifically designed for nonconvex mixed integer nonlinear programming problems and it can be successfully applied to both global and constrained optimization. In previous studies, we have demonstrated the efficiency of the GHA in solving complicated NLP, INLP and MINLP problems. The present study is a continuation of this research, now focusing on a set of highly irregular optimization problems. In this paper we discuss the genetic hybrid algorithm, the nonlinear problems to be solved and present the results of the empirical tests.
A spatially-adaptive bus interface for low-switching communication (poster session)
Authors: Andrea Acquaviva, Riccardo Scarsi
Venue: Proceedings of the 2000 international symposium on Low power electronics and design (2000)

Adaptive encoding has shown to be an effective approach to bus power minimization in situations where characterization of the input statistics is not available. In this paper, we propose a novel technique for adaptive bus encoding that, conversely from existing solutions, exploits spatial correlations in the input data being transmitted to increase the accuracy in the dynamic selection of the encoding function. We discuss the encoding algorithm and we describe an architecture for its implementation as bus interface. We present experimental data collected in a realistic simulation framework on a number of meaningful benchmarks, and we compare them to those obtained through the application of existing encoding schemes.Adaptive encoding has shown to be an effective approach to bus power minimization in situations where characterization of the input statistics is not available. In this paper, we propose a novel technique for adaptive bus encoding that, conversely from existing solutions, exploits spatial correlations in the input data being transmitted to increase the accuracy in the dynamic selection of the encoding function. We discuss the encoding algorithm and we describe an architecture for its implementation as bus interface. We present experimental data collected in a realistic simulation framework on a number of meaningful benchmarks, and we compare them to those obtained through the application of existing encoding schemes.
WASS: wireless ATM security system
Authors: Danai Patiyoot, S. J. Shepherd
Venue: ACM SIGOPS Operating Systems Review (1999)

Recent years have witnessed the rapid growth in demanding for the use of wireless networks especially the one with can transmit all the service. Wireless ATM is the one that fulfil those requirements. Various architectures have been proposed depending on the intended application domain. One of the key components is the security protocol. This paper tries to propose security service into the wireless ATM network.
The anthropology semaphores
Authors: Yifat Ben-David Kolikant, Mordechai Ben-Ari, Sarah Pollack
Venue: Proceedings of the 5th annual SIGCSE/SIGCUE ITiCSEconference on Innovation and technology in computer science education (2000)

This paper describes research into the conceptions of students studying concurrency, using qualitative methods that originated in anthropological field work. We were able to obtain a deep understanding of students' mental models of semaphores: they construct consistent, though non-viable, models of semaphores, and they use them in patterns without understanding the synchronization context. We used the results to improve our teaching of concurrency, for example, by carefully defining the semaphore model and exercising the model outside of a problem-solving context.
Infinite Horizon Production Planning in Time-Varying Systems with Convex Production and Inventory Costs
Authors: Robert L. Smith, Rachel Q. Zhang
Venue: Management Science (1998)

We consider the planning of production over the infinite horizon in a system with time-varying convex production and inventory holding costs. This production lot size problem is frequently faced in industry where a forecast of future demand must be made and production is to be scheduled based on the forecast. Because forecasts of the future are costly and difficult to validate, a firm would like to minimize the number of periods into the future it needs to forecast in order to make an optimal production decision today. In this paper, we first prove that under very general conditions finite horizon versions of the problem exist that lead to an optimal production level at any decision epoch. In particular, we show it suffices for the first period infinite horizon production decision to solve for a horizon that exceeds the longest time interval over which it can prove profitable to carry inventory. We then develop a closed-form expression for computing such a horizon and provide a simple finite algorithm to recursively compute an infinite horizon optimal production schedule.
GUARDS: A Generic Upgradable Architecture for Real-Time Dependable Systems
Authors: D. Powell, J. Arlat, L. Beus-Dukic, A. Bondavalli, P. Coppola, A. Fantechi, E. Jenn, C. Rabéjac, A. Wellings
Venue: IEEE Transactions on Parallel and Distributed Systems (1999)

The development and validation of fault-tolerant computers for critical real-time applications are currently both costly and time consuming. Often, the underlying technology is out-of-date by the time the computers are ready for deployment. Obsolescence can become a chronic problem when the systems in which they are embedded have lifetimes of several decades. This paper gives an overview of the work carried out in a project that is tackling the issues of cost and rapid obsolescence by defining a generic fault-tolerant computer architecture based essentially on commercial off-the-shelf (COTS) components (both processor hardware boards and real-time operating systems). The architecture uses a limited number of specific, but generic, hardware and software components to implement an architecture that can be configured along three dimensions: redundant channels, redundant lanes, and integrity levels. The two dimensions of physical redundancy allow the definition of a wide variety of instances with different fault tolerance strategies. The integrity level dimension allows application components of different levels of criticality to coexist in the same instance. The paper describes the main concepts of the architecture, the supporting environments for development and validation, and the prototypes currently being implemented.
A Bound on the Solution to a Structured Sylvester Equation with an Application to Relative Perturbation Theory
Authors: Ren-Cang Li
Venue: SIAM Journal on Matrix Analysis and Applications (1999)

Assuming only that the spectra of A and B are disjoint as opposed to the more restrictive assumption previously used, we obtain a bound in all unitarily invariant norms on the solution to the structured Sylvester equation AX - XB = A1/2EB1/2. This bound is the first of its kind in all unitarily invariant norms under only the disjointedness assumption. An application of the bound to the relative perturbation theory for scaled Hermitian eigenvalue problems is given.
A componentized architecture for dynamic electronic markets
Authors: Benny Reich, Israel Ben-Shaul
Venue: ACM SIGMOD Record (1998)

The emergence and growing popularity of Internet-based electronic market-places, in their various forms, has raised the challenge to explore genericity in market design. In this paper we present a domain-specific software architecture that delineates the abstract components of a generic market and specifies control and data-flow constraints between them, and a framework that allows convenient pluggability of components that implement specific market policies. The framework was realized in the GEM system. GEM provides infrastructure services that allow market designers to focus solely on market-issues. In addition, it allows dynamic (re)configuration of components. This functionality can be used to change market-policies as the environment or market trends change, adding another level of flexibility to market designers and administrators.
An Object-Oriented Framework for Loop Parallelization
Authors: Youichi Omori, Akira Fukuda, Kazuki Joe
Venue: The Journal of Supercomputing (1999)

Generation of efficient parallel code is a major goal of a well-designed and developed parallelizing compiler. Another important goal is portability of both compiler system and the resulting output source codes. The various choices of current and future parallel computer architectures as well as the cost of developing a parallelizing compiler make portability a very important design goal. Since the design of parallelizing compilers is considerably move complex than designing conventional compilers, it is very important to achieve both efficiency and portability. To meet this dual goal, we have investigated the application of object oriented design to parallelizing compilers. Our parallelizing compiler design is based on abstractions of intermediate representations of loops and their class definitions. In this paper, we address the problem of loop parallelization and propose a framework where the loop parallelization process is divided into three phases and the optimization of loops is performed via a cyclic application of these three phases. The class of each phase is hierarchically derived from intermediate representations of loops. This facilitates the portability of the resulting parallelizing compilers. Furthermore, one of the phases uses a reservation table of hardware resources in order to obtain optimized parallel programs for given hardware resources. The validation of the proposed framework is given through the application of the object oriented design on an example program which is then parallelized efficiently.
Row-Major Sorting on Meshes
Authors: Jop F. Sibeyn
Venue: SIAM Journal on Computing (1999)

In all recent near-optimal sorting algorithms for meshes, the packets are sorted with respect to some snake-like indexing. In this paper we present deterministic algorithms for sorting with respect to the more natural row-major indexing. For 1-1 sorting on an n &times; n mesh, we give an algorithm that runs in 2 &middot; n + o(n) steps, matching the distance bound, with maximal queue size five. It is considerably simpler than earlier algorithms. Another algorithm performs k-k sorting in k &middot; n / 2 + o(k &middot; n) steps, matching the bisection bound. Furthermore, we present uniaxial algorithms for row-major sorting. We show that 1-1 sorting can be performed in $2 \frac{1}{2} &middot; n + o(n) steps. Alternatively, this problem is solved with maximal queue size five in $4 \frac{1}{3} &middot; n steps, without any additional terms.