ppxscal/embedding_network huggingface dataset:
An approach to detecting changes in the factors affecting the performance of computer systems
Authors: Robert Berry, Joseph Hellerstein
Venue: ACM SIGMETRICS Performance Evaluation Review (1991)

Resolving intermittent performance problems in computer systems is made easier by pinpointing when a change occurs in the system's perforrnance-determinin g factors (e.g., workload composition, configuration). Since we often lack direct measurements of performance factors, this paper presents a procedure for indirectly detecting such changes by analyzing performance characteristics (e.g., response times, queue lengths). Our procedure employs a widely used clustering algorithm to identify candidate change points (the times at which performance factors change), and a newly developed statistical test (based on an AR(1) time series model) to determine the signficance of candidate change points. We evaluate our procedure by using simulations of M/M/1, FCFS queueing systems and by applying our procedure to measurements of a mainframe computer system at a large telephone company. These evaluations suggest that our procedure is effective in practice, especially for larger sample sizes and smaller utilizations. We further conclude that indirectly detecting changes in performance factors appears to be inherently difficult in that the sensitivity of a detection procedure depends on the magnitude of the change in performance characteristics, which often has a nonlinear relationship with the change in performance factors. Thus, a change in performance factors (e.g., increased service times) may be more readily detected in some situations (e.g., very low or very high utilizations) than in others (e.g., moderate utilizations). A key insight here is that the sensitivity of the detection procedure can be improved by choosing appropriate measures of performance characteristics. For example, our experience and analysis suggest that queue lengths can be more sensitive than response times to changes in arrival rates.
Interactive Systems: Bridging the Gaps Between Developers and Users
Authors: Jonathan Grudin
Venue: Computer (1991)

Three development contexts are examined to provide a framework for understanding interactive software development projects. These contexts are the competitively bid, commercial product, and in-house/custom contexts development. Factors influencing interactive systems development are examined. Specific strategies to cope with the gaps between developers and prospective users are explored at the general level of the three development paradigms.
A geometric approach to presenting computer representations of integers
Authors: James W. Benham
Venue: ACM SIGCSE Bulletin (1992)

The student's first serious exposure to computer arithmetic typically occurs in a sophomore course in machine architecture or assembler language. A glance at several excellent and widely used texts for these courses (for example [M], [Sh], [St], [T]) shows that this material is often presented as an unmotivated set of mechanical rules to, for example, add numbers using one's complement notation or compute the two's complement representation of a negative integer. This paper describes a way to motivate these topics by relating them to the computer's "natural " arithmetic.
Using delayed commitment in locking protocols for real-time databases
Authors: D. Agrawal, A. El Abbadi, R. Jeffers
Venue: Proceedings of the 1992 ACM SIGMOD international conference on Management of data (1992)

In this paper, we propose locking protocols that are useful for real-time databases. Our approach is motivated from two main observations. First, locking protocols are widely accepted and used in most database systems. Second, in real-time databases it has been shown that the blocking behavior of transactions in locking protocols results in performance degradation. We use a new relationship between locks called ordered sharing to eliminate blocking that arises in the traditional locking protocols. Ordered sharing eliminates blocking of read and write operations but may result in delayed commitment. Since in real-time databases, timeliness and not response time is the crucial factor, or protocols exploit this delay to allow transactions to execute within the slacks of delayed transactions. We compare the performance of the proposed protocols with the two phase locking protocol for real-time databases. Our experiments indicate that the propose protocols significantly reduce the percentage of missed deadlines in the system for a variety of workloads.
On robust transaction routing and load sharing
Authors: Philip S. Yu, Avraham Leff, Yann-Hang Lee
Venue: ACM Transactions on Database Systems (TODS) (1991)

In this paper we examine the issue of robust transaction routing in a locally distributed database environment where transaction characteristics such as reference locality imply that certain processing systems can be identified as being more suitable than others for a given transaction class. A response time based routing strategy can strike a balance between indiscriminate sharing of the load and routing based only on transaction affinity. Since response time estimates depend on workload and system parameters that may not be readily available, it is important to examine the robustness of routing decisions to information accuracy. We find that a strategy which strictly tries to minimize the response time of incoming transactions is sensitive to the accuracy of certain parameter values. On the other hand, naive strategies, that simply ignore the parameters in making routing decisions, have even worse performance. Three alternative strategies are therefore examined: threshold, discriminatory, and adaptive. Instead of just optimizing an incoming transaction's response time, the first two strategies pursue a strategy that is somewhat more oriented towards global optimization. This is achieved by being more restrictive on either the condition or the candidate for balancing the load. The third strategy, while trying to minimize the response time of individual incoming transactions, employs a feedback process to adaptively adjust future response time estimates. It monitors the discrepancy between the actual and estimated response times and introduces a correction factor based on regression analysis. All three strategies are shown to be robust with respect to the accuracy of workload and system parameters used in the response time estimation.
NEURONET: A Distributed Real-Time System for Monitoring Neurophysiologic Function in the Medical Environment
Authors: Don Krieger, Gerald Burk, Robert J. Sclabassi
Venue: Computer (1991)

A specific medical application, namely repair of a narrow aorta in children, served by Neuronet, a large software package integrated with 80 computer workstations and instrumentation, is considered to demonstrate the offline and real-time capabilities of the package. An overview of the system is given, and a case example is presented. The system's remote capabilities, signal processing, user interface, and database are discussed. Reliability and upgradeability are considered.
Propagators and concurrent constraints
Authors: Chris Laffra, Jan van den Bos
Venue: Proceedings of the workshop on Object-based concurrent programming (1991)

A constraint is a numeric or geometric relationship between objects. Constraints have a declarative nature and are a natural way for describing relationships between objects. Combining constraint systems and object-oriented programming (OOP) appears hard. All existing systems implicitly compromise the encapsulation principle of OOP. Also, the constraint resolving mechanism is typically centralized, thereby restricting parallel execution of a constraint program. This paper proposes a mechanism that provides for constraints in the concurrent (parallel) object-oriented Procol environment. Constraints are implemented using propagators. Propagators are triggered by messages that are sent to objects. Propagator constraints are solved by local propagation of known state, intuitively allowing for parallel execution of a Procol constraint program.
Parallel unit tangent vector computation for homotopy curve tracking on a hypercube
Authors: A. Chakraborty, D. C. S. Allison, C. J. Ribbens, L. T. Watson
Venue: Proceedings of the 1990 ACM annual conference on Cooperation (1990)

Probability-one homotopy methods are a class of methods for solving nonlinear systems of equations that are globally convergent from an arbitrary starting point. The essence of all such algorithms is the construction of an appropriate homotopy map and subsequent tracking of some smooth curve in the zero set of the homotopy map. Tracking a homotopy curve involves finding the unit tangent vectors at different points along the zero curve. Because of the way a homotopy map is constructed, the unit tangent vector at each point in the zero curve of a homotopy map &rgr;a(&lgr;,&khgr;) is in the kernel of the Jacobian matrix D&rgr;a(&lgr;,&khgr;). Hence, tracking the zero curve of a homotopy map involves finding the kernel of the Jacobian matrix D&rgr;a(&lgr;,&khgr;). The Jacobian matrix D&rgr;a is a n &times; (n+1) matrix with full rank. Since the accuracy of the unit tangent vector is very important, an orthogonal factorization instead of an LU factorization of the Jacobian matrix is computed. Two related orthogonal factorizations, namely QR and LQ factorization, are considered here. This paper presents computational results showing the performance of several different parallel orthogonal factorization/triangular system solving algorithms on a hypercube. Since the purpose of this study is to find ways to parallelize homotopy algorithms, it is assumed that the matrices have a special structure such as that of the Jacobian matrix of a homotopy map. In particular, we are interested in relatively small and dense Jacobians.
A Generalized Multibit Recoding of Two's Complement Binary Numbers and its Proof with Application in Multiplier Implementations
Authors: H. Sam, A. Gupta
Venue: IEEE Transactions on Computers (1990)

A multibit recoding algorithm for signed two's complement binary numbers is presented and proved. In general, a k+1-bit recoding will result in a signed-digit (SD) representation of the binary number in radix 2/sup k/, using digits -2/sup k-1/ to +2/sup k-1/ including 0. It is shown that a correct SD representation of the original number is obtained by scanning K+1-tuples (k¿1) with one bit overlapping between adjacent groups. Recording of binary numbers has been used in computer arithmetic with 3-bit recoding being the dominant scheme. With the emergence of very high speed adders, hardware parallel multipliers using multibit recoding with k
Optimal placement of high-probability randomly retrieved blocks on CLV optical discs
Authors: Daniel Alexander Ford, Stavros Christodoulakis
Venue: ACM Transactions on Information Systems (TOIS) (1991)

Optimal data placement on a CLV (Constant Linear Velocity) format optical discs has an objective the minimization of the expected access cost of data retrievals from the disc when the probabilities of access of data items may be different. The problem of optimal data placement for optical discs is both important and more difficult than the corresponding problem on magnetic discs. A good data placement on optical discs is more important because data sets on optical discs such as WORM and CD ROM cannot be modified or moved once they are placed on disc. Currently, even rewritable optical discs are best suited for applications that are archival in nature. The problem of optimal data placement on CLV format optical discs is more difficult, mainly because the useful storage space is not uniformly distributed across the disc surface (along the radius). This leads to a complicated positional performance trade-off not present for magnetic disks. We present a model that encompasses all the important aspects of the placement problem on CLV format optical discs. The model takes into account the nonuniform distribution of useful storage, the dependency of the rotational delay on disc position, a parameterized seek cost function for optical discs, and the varying access probabilities of data items. We show that the optimal placement of high-probability blocks satisfies a unimodality property. Based on this observation, we solve the optimal placement problem. We then study the impact of the relative weights of the problem parameters and show that the optimal data placement may be very different from the optimal data placement on magnetic disks. We also validate our model and analysis and give an algorithm for computing the placement of disc sectors.
Optimization by simulated evolution with applications to standard cell placement
Authors: Ralph-Michael Kling, Prithviraj Banerjee
Venue: Proceedings of the 27th ACM/IEEE Design Automation Conference (1991)

This paper presents a mathematical formulation of the Simulated Evolution algorithm, a novel optimization technique, followed by a thorough analysis of the associated Markovchain model. We show that the algorithm will reach a global minimum with probability one, and also introduce a novel hierarchical placement technique. Finally, we describe a Standard Cell placement program based on the new approach whose preliminary results are comparable to the best Simulated Annealing algorithms.
New hope on data models and types: report of an NSF-INRIA workshop
Authors: Serge Abiteboul, Peter Buneman, Claude Delobel, Richard Hull, Paris Kanellakis, Victor Vianu
Venue: ACM SIGMOD Record (1990)

In May, 1990, a small workshop was held in New Hope, Pennsylvania, to discuss the fundamental issues raised by continuing work on the interface between databases and programming languages. Four topics were addressed: new directions stemming from object-oriented data models, contributions of type theory to database programming languages (DBPLs), applications of logic to DBPL issues, and DBPL implementations. This workshop was organized under the auspices of the INRIA-NSF program, Languages for Databases and Knowledge Bases.
An adaptive timing-driven layout for high speed VLSI
Authors: Suphachai Sutanthavibul, Eugene Shragowitz
Venue: Proceedings of the 27th ACM/IEEE Design Automation Conference (1991)

An adaptive timing-driven layout system, called JUNE, has been developed. The constructive algorithm, which combines placement with the global routing, constructs a placement satisfying timing and routability constraints. The placement problem for each macro is solved hierarchically as a sequence of two optimization problems followed by an adaptive correction procedure. Experimental results for industrial sea-of-gates chips confirmed effectiveness of this approach.
Small Sample Error Rate Estimation for k-NN Classifiers
Authors: Sholom M. Weiss
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1991)

Small sample error rate estimators for nearest-neighbor classifiers are examined and contrasted with the same estimators for three-nearest-neighbor classifiers. The performance of the bootstrap estimators, e0 and 0.632B, is considered relative to leaving-one-out and other cross-validation estimators. Monte Carlo simulations are used to measure the performance of the error-rate estimators. The experimental results are compared to previously reported simulations for nearest-neighbor classifiers and alternative classifiers. It is shown that each of the estimators has strengths and weaknesses for varying apparent and true error-rate situations. A combined estimator that corrects the leaving-one-out estimator (by combining bootstrap and cross-validation estimators) gives strong results over a broad range of situations.
Towards a probabilistic modal logic for semantic-based information retrieval
Authors: Jian-Yun Nie
Venue: Proceedings of the 15th annual international ACM SIGIR conference on Research and development in information retrieval (1992)

Semantic-based approaches to Information Retrieval make a query evaluation similar to an inference process based on semantic relations. Semantic-based approaches find out hidden semantic relationships between a document and a query, but quantitative estimation of the correspondence between them is often empiric. On the other hand, probabilistic approaches usually consider only statistical relationships between terms. It is expected that improvement may be brought by integrating these two approaches. This paper demonstrates, using some particular probabilistic models which are strongly related to modal logic, that such an integration is feasible and natural. A new model is developed on the basis of an extended modal logic. It has the advantages of : (1) augmenting a semantic-based approach with a probabilistic measurement, and (2) augmenting a probabilistic approach with finer semantic relations than just statistical ones. It is shown that this model verifies most of the conditions for an absolute probability function.
Multiprocessor Performance-Measurement Instrumentation
Authors: Alan Mink, Robert Carpenter, George Nacht, John Roberts
Venue: Computer (1990)

Performance measurement for loosely and tightly coupled multiple-instruction multiple-data multiprocessor systems is addressed. For the paradigm of multiple processors solving a single problem faster, a taxonomy of hardware-supported measurement approaches is presented and critiqued. A hybrid measurement system that is, software with hardware support, is presented. The system, called the trace measurement system (Trams), initially consisted of a memory-mapped device using software triggering and hardware sampling of time and processor identification. A VLSI chip set that integrates the Trams functions of software triggering and hardware sampling with hardware counters is described, and its application is discussed. The tool introduces little perturbation and provides physically small and affordable performance-measurement support.
Programming Persistence in "
Authors: A. S. M. Sajeev, A. John Hurst
Venue: Computer (1992)

The ways in which a persistent programming language allows the reuse of data and code objects by preserving them as persistent objects is discussed. The programming language chi , which supports persistent programming, is described. The language is innovative in that it elevates capabilities to the programming level and gives the programmer a convenient way to express which objects are persistent independently of the type of object. Thus, it provides orthogonal persistence. A further advantage that follows from such use of capabilities is that chi provides an implementation path for persistence, even upon architectures that do not support capabilities directly.
High-Resolution Terrain Map from Multiple Sensor Data
Authors: In So Kweon, Takeo Kanade
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1992)

The authors present 3-D vision techniques for incrementally building an accurate 3-D representation of rugged terrain using multiple sensors. They have developed the locus method to model the rugged terrain. The locus method exploits sensor geometry to efficiently build a terrain representation from multiple sensor data. The locus method is used to estimate the vehicle position in the digital elevation map (DEM) by matching a sequence of range images with the DEM. Experimental results from large-scale real and synthetic terrains demonstrate the feasibility and power of the 3-D mapping techniques for rugged terrain. In real world experiments, a composite terrain map was built by merging 125 real range images. Using synthetic range images, a composite map of 150 m was produced from 159 images. With the proposed system, mobile robots operating in rugged environments can build accurate terrain models from multiple sensor data.
Theorem proving in propositional logic on vector computers using a generalized Davis-Putnam procedure
Authors: Wen-Tsuen Chen, Ming-Yi Fang
Venue: Proceedings of the 1990 ACM/IEEE conference on Supercomputing (1990)

The Davis-Putnam procedure (DPP) is an efficient and well-known method for solving the theorem proving problem in propositional logic. In this paper, we present an effective technique for vectorizing the DPP. To speed up the execution of DPP, the rules used by the procedure is first generalized by considering more than one literal at a time. Then vectorized algorithms based on the generalized rules are proposed. Experiments are conducted on vector computers. The results show the vectorized version of the Davis-Putnam procedure is effective in solving a variety of instances of theorem proving problem in propositional logic.
The IL programming language
Authors: Randy M. Kaplan
Venue: ACM SIGPLAN Notices (1991)

IL is a language for developing mouse-driven interactive applications. It is an example of a "little language" as described by Jon Bentley (1986). We conceived IL as a tool for building interactive applications based on an event-driven model. When an event occurs, the systems performs one or more specified actions. By supporting this interactive model the programmer can concentrate on the details of the interactive application as opposed to the details of a specific interaction.
Classifying news stories using memory based reasoning
Authors: Brij Masand, Gordon Linoff, David Waltz
Venue: Proceedings of the 15th annual international ACM SIGIR conference on Research and development in information retrieval (1992)

We describe a method for classifying news stories using Memory Based Reasoning (MBR) a k-nearest neighbor method), that does not require manual topic definitions. Using an already coded training database of about 50,000 stories from the Dow Jones Press Release News Wire, and SEEKER [Stanfill] (a text retrieval system that supports relevance feedback) as the underlying match engine, codes are assigned to new, unseen stories with a recall of about 80% and precision of about 70%. There are about 350 different codes to be assigned. Using a massively parallel supercomputer, we leverage the information already contained in the thousands of coded stories and are able to code a story in about 2 seconds. Given SEEKER, the text retrieval system, we achieved these results in about two person-months. We believe this approach is effective in reducing the development time to implement classification systems involving large number of topics for the purpose of classification, message routing etc.
FDDI and timing requirements for image transmission
Authors: B. Cousin
Venue: Proceedings of the 1992 ACM annual conference on Communications (1992)

This article presents the timing requirements for digitalized video transmission and the synchronous transmission mode of the Fiber Distributed Data Interface (FDDI) protocol. First, we develop a timed model of the FDDI protocol and we prove that it meets its standard requirement. Secondly, we verify that the temporal constraints for real time image transmission are fulfilled by the FDDI protocol.
Overflow/Underflow-Free Floating-Point Number Representations with Self-Delimiting Variable-Length Exponent Field
Authors: Hidetoshi Yokoo
Venue: IEEE Transactions on Computers (1992)

A class of new floating-point representations of real numbers, based on representations of the integers, is described. In the class, every representation uses a self-delimiting representation of the integers as a variable length field of the exponent, and neither overflow nor underflow appears in practice. The adopted representations of the integers are defined systematically, so that representation's of numbers greater than one have both exponent-significant and integer-fraction interpretations. Since representation errors are characterized by the length function of an underlying representation of the integers, superior systems in precision can be easily selected from the proposed class.