ppxscal/embedding_network huggingface dataset:
Control of a Camera for Active Vision: Foveal Vision, Smooth Tracking and Saccade
Authors: Ehud Rivlin, Héctor Rotstein
Venue: International Journal of Computer Vision (2000)

Several characteristics of the human oculomotor system have been suggested to be useful also for active vision mechanisms. Among others, foveal vision and a tracking scheme based on two different modes, called smooth pursuit and saccade have often been postulated or implemented. The purpose of this paper is to formulate a setup in which the benefit of implementing these schemes can be evaluated in a systematic manner, based on control considerations but incorporating image processing constraints. First, the advantage of using foveal vision is evaluated by computing the size of the foveal window which will allow tracking of the largest possible class of signals. By using linear optimal control theory, this problem can be formulated as a one-variable maximization.Second, foveal vision leads naturally to smooth pursuit, defined as the performance that can be achieved by the controller resulting in the optimal size of the foveal window. This controller is relatively simple (i.e., linear, time-invariant) as is to be expected for this control loop.Finally, when smooth pursuit fails a corrective action must be performed to re-center the target on the fovea. Recent results in linear optimal control, provide the necessary tools for addressing this challenging problem in a systematic manner.
Microcomputers as remote nodes of a distributed system
Authors: Michael A. Pechura
Venue: Communications of the ACM (1981)

A time-sharing system may be extended into a general-purpose distributed computing facility through the use of remote microcomputer systems. In such an extension the microcomputer system is not merely a remote terminal but a complete computer system. It becomes part of an integrated network of computers, each with significant local computational power with access to host system data resources. The implementation described emphasizes ease-of-use by minimizing any differences between local and remote data use.
SciCentr and BioLearn: two 3D implementations of CVE science museums
Authors: Margaret Corbit, Bonnie DeVarco
Venue: Proceedings of the third international conference on Collaborative virtual environments (2000)

In this paper, we present and compare two examples of the use of the Active Worlds client/server technology for implementation of 3D multi-user virtual science museums: SciCentr, developed as a standalone environment at the Cornell Theory Center, Cornell University's high-performance computing center, and Biolearn, a virtual visitors center for the proposed LifeLearn Bioregional Learning Center on the Northern California Coast. SciCenter focuses on interactive exhibits analogous to those of a traditional hands-on science center, but presented solely within the virtual space. In contrast, BioLearn is designed to provide a globally accessible interactive tour of the seaside museum and preserve by offering web-based information about the bioregion in a dynamic, natural 3D setting.
Models for parallel processing within programs: application to CPU: I/O and I/O: I/O overlap
Authors: D. Towsley, K. M. Chandy, J. C. Browne
Venue: Communications of the ACM (1978)

Approximate queueing models for internal parallel processing by individual programs in a multiprogrammed system are developed in this paper. The solution technique is developed by network decomposition. The models are formulated in terms of CPU:I/O and I/O:I/O overlap and applied to the analysis of these problems. The percentage performance improvement from CPU:I/O overlap is found to be greatest for systems which are in approximate CPU:I/O utilization balance and for low degrees of multiprogramming. The percentage improvement from I/O:I/O overlap is found to be greatest for systems in which the I/O system is more utilized than the CPU.
Implementation of state machines with tasks and protected objects
Authors: Bo I. Sandén
Venue: ACM SIGAda Ada Letters (2000)

State machines are common in real-time software. They are also a standard way of describing the life of an object in object-oriented analysis and design. Their use is fairly straightforward but non-trivial. The examples in this article show implementations of state machines and associated activities by means of tasks and protected objects. They cover a range of synchronization and communication needs between activity and state machine.
Improving fine-grained irregular shared-memory benchmarks by data reordering
Authors: Y. Charlie Hu, Alan Cox, Willy Zwaenepoel
Venue: Proceedings of the 2000 ACM/IEEE conference on Supercomputing (CDROM) (2000)

We demonstrate that data reordering can substantially improve the performance of fine-grained irregular shared-memory benchmarks, on both hardware and software shared-memory systems. In particular, we evaluate two distinct data reordering techniques that seek to co-locate in memory objects in close proximity in the physical system modeled by the computation. The effects of these techniques are increased spatial locality and reduced false sharing. We evaluate the effectiveness of the data reordering techniques on a set of five irregular applications from SPLASH-2 and Chaos. We implement both techniques in a small library, allowing us to enable them in an application by adding less than 10 lines of code. Our results on one hardware and two software shared-memory systems show that, with data reordering during initialization, the performance of these applications is improved by 12 percent to 99 percent on the Origin 2000, 30 percent to 366 percent on TreadMarks, and 14 percent to 269 percent on HLRC.
A report on industry-University roundtable discussions on recruitment and retention of high-tech professionals
Authors: Mary Sumner
Venue: Proceedings of the 2001 ACM SIGCPR conference on Computer personnel research (2001)

The purpose of this paper is to synthesize the proceedings of the 1998-1999 and 1999-2000 Technology and Commerce Roundtables on the topic of the &ldquo;Recruitment and Retention of High-Tech Professionals&rdquo; and to raise issues and challenges which have been generated from these discussions. The paper will address the responses of corporate partners, students, and the university faculty with respect to the recruitment and retention of IT professionals, skill and knowledge requirements for IT personnel, the factors important to MIS graduates in selecting career opportunities, the impact of commercial off-the-shelf software on IT skill requirements, and IT compensation strategies.
Performing remote operations efficiently on a local computer network
Authors: Alfred Z. Spector
Venue: Communications of the ACM (1982)

A communication model is described that can serve as a basis for a highly efficient communication subsystem for local networks. The model contains a taxonomy of communication instructions that can be implemented efficiently and can be a good basis for interprocessor communication. These communication instructions, called remote references, cause an operation to be performed by a remote process and, optionally, cause a value to be returned. This paper also presents implementation considerations for a communication system based upon the model and describes an experimental communication subsystem that provides one class of remote references. These remote references take about 150 microseconds or 50 average instruction times to perform on Xerox Alto computers connected by a 2.94 megabit Ethernet.
Ranking the complexity of NIAM conceptual schemas by alpha metric
Authors: Peter Kokol, Vili Podgorelec
Venue: ACM SIGPLAN Notices (2000)

The general aim of formal methods to program development is to provide correctness of the problem specification and then to transform that specification into a working program. Often a formal specification is expressed using the NIAM conceptual schema. If we consider only valid types of constraints and if we keep all the consistent schemas, we have 28 possible schemas and 7 sub -- schemas for each schema. The schemas and sub - schemas have very different complexities and there exists an intuitive order of these complexities which seems to be problematical. The aim of this paper is to verify this order using a complexity measure called alpha; (information content/entropy metrics) and to define a new ranking functions generating more correct order.
A fast algorithm for computing longest common subsequences
Authors: James W. Hunt, Thomas G. Szymanski
Venue: Communications of the ACM (1977)

Previously published algorithms for finding the longest common subsequence of two sequences of length n have had a best-case running time of O(n2). An algorithm for this problem is presented which has a running time of O((r + n) log n), where r is the total number of ordered pairs of positions at which the two sequences match. Thus in the worst case the algorithm has a running time of O(n2 log n). However, for those applications where most positions of one sequence match relatively few positions in the other sequence, a running time of O(n log n) can be expected.
Collision detection and response for computer animationr3
Authors: Matthew Moore, Jane Wilhelms
Venue: Proceedings of the 15th annual conference on Computer graphics and interactive techniques (1988)

When several objects are moved about by computer animation, there is the chance that they will interpenetrate. This is often an undesired state, particularly if the animation is seeking to model a realistic world. Two issues are involved: detecting that a collision has occurred, and responding to it. The former is fundamentally a kinematic problem, involving the positional relationship of objects in the world. The latter is a dynamic problem, in that it involves predicting behavior according to physical laws. This paper discusses collision detection and response in general, presents two collision detection algorithms, describes modeling collisions of arbitrary bodies using springs, and presents an analytical collision response algorithm for articulated rigid bodies that conserves linear and angular momentum.
Tensor calculations on computer: appendix
Authors: John J. Walton
Venue: Communications of the ACM (1967)

In the main text of the paper [Comm. ACM 9, 12 (Dec. 1966), 864], a FORMAC program was discussed which is capable of calculating various quantities of interest in tensor calculus. This Appendix is intended as an example of the program output. Christoffel symbols calculated for 12 basic orthogonal coordinate systems are listed.
Register-constrained address computation in DSP programs
Authors: A. Basu, R. Leupers, P. Marwedel
Venue: Proceedings of the conference on Design, automation and test in Europe (1998)

This paper describes a new code optimization technique for digital signal processors (DSPs). One important characteristic of DSP algorithms are iterative accesses to data array elements within loops. DSPs support efficient address computations for such array accesses by means of dedicated address generation units (AGUs). We present a heuristic technique which, given an AGU with a fixed number of address registers, minimizes the number of instructions needed for array address computations in a program loop.
A pipelined ADC macro design for multiple applications
Authors: Kuniyuki Tani, Norihiro Nikai, Atsushi Wada, Tetsuro Sawai
Venue: Proceedings of the 2001 Asia and South Pacific Design Automation Conference (2001)

We present a new design methodology for high-speed Analog-to-Digital Converter (ADC) macros based on our original pipelined 10-bit ADC. With library re-use methodology and performance driven optimization techniques, we have been able to both shorten the design period and to meet application specifications for items such as speed and power consumption. Using this method, we have developed ADC macros from 10-bit to 8-bit and 6-bit. They can be embedded into system LSIs for communication and multimedia applications.
A dynamically phase adjusting PLL with a variable delay
Authors: Takeo Yasuda, Hiroaki Fujita, Hidetoshi Onodera
Venue: Proceedings of the 2001 Asia and South Pacific Design Automation Conference (2001)

Phase locked loop (PLL) is widely used for many purposes. The lock-up performance is one of the most important target items in designing PLLs. In a digital PLL, it is difficult to control the frequency and phase independently, which makes it difficult to improve lock-up performance. A variable delay circuit which adjusts only the phase of the PLL is introduced here. A full loop model simulation with measured controllable delay shows the effectiveness of applying the phase adjust method with the variable delay to the PLL. Index Terms - PLL, phase adjust, variable delay, lock-up.
Java meets teletubbies: an interaction between program codes and physical props
Authors: Josiah Poon
Venue: Proceedings of the Australasian conference on Computing education (2000)

Teaching students a computer language is not just about teaching them the syntax of a language. It is the underlying concepts behind the language features that are important. In our School, Java is offered as an introductory subject and is becoming the official of students for all our I.T. students. Due to the diversity of students in the first year, it is a challenge to bring all these students to the same level of understanding in some of the issues are theories. It is especially hard when some of the issues are not popular in the physical world. Having said that, our understanding of the environment comes from our interaction with the physical objects around us. We are accustomed to use these concrete items to help comprehend and develop more advanced knowledge. Hence, it is hypothesed that the use of physical props in teaching programming language is beneficial to students in constructing mental models of the abstract programming concepts. The mental model allows them to simulate and to experiment relevant issues without the actual coding. An experiment was designed to interplay the program codes in both the real world and the virtual environment. This approach proved to be very effective to facilitate students in building mental models during the learning process.
Information retrieval system using real world objects
Authors: Hiroaki Tobita, Hideki Koike
Venue: Proceedings of DARE 2000 on Designing augmented reality environments (2000)

In this position paper we bring a new approach &mdash; Value-Sensitive Design &mdash; to understanding the value implications of augmented reality. We examine seven values: psychological well-being, physical well-being, privacy, deception, informed consent, ownership and property, and trust. In addition, we briefly describe our work where we apply a Value-Sensitive Design approach to augmented reality of the natural world.
The multistore parser for hierarchical syntactic structures
Authors: Ernst von Glasersfeld, Pier Paolo Pisani
Venue: Communications of the ACM (1970)

A syntactic parser is described for hierarchical concatenation patterns that are presented to the analyzer in the form of linear strings. Particular emphasis is given to the system of &ldquo;significant addresses&rdquo; by means of which processing times for large-scale matching procedures can be substantially reduced. The description makes frequent use of examples taken from the fully operational implementation of the parser in an experimental English sentence analyzer. By structuring an area of the computer's central core storage in such a way that the individual locations of bytes and bits come to represent the data involved in the matching procedure, the shifting of information is reduced to a minimum, and the searching of lists is eliminated altogether. The matches are traced by means of binary masks and the state of single bits determines the operational flow of the procedure. The method could be implemented with any interpretive grammar, provided it can be expressed by the functional classification of the items composing the input hierarchical structures.
An 8-b nRERL microprocessor for ultra-low-energy applications
Authors: Seokkee Kim, Jun-Ho Kwon, Soo-Ik Chae
Venue: Proceedings of the 2001 Asia and South Pacific Design Automation Conference (2001)

We describe the design of an nRERL microprocessor for ultra-low-energy applications. nRERL (nMOS Reversible Energy Recovery Logic) is a new reversible adiabatic logic circuit using only nMOS transistors, which can be operated at the leakage-current level [1]. We focus on two main issues; first, the design of a full adiabatic microprocessor, which uses only adiabatic components for all the functional blocks, second, the energy consumption of the nRERL microprocessor including its clocked power generator (CPG). With the experimental results, the nRERL microprocessor consumed 26.22 pJ at 440 kHz.
A technique for software module specification with examples
Authors: D. L. Parnas
Venue: Communications of the ACM (1983)

This paper presents an approach to writing specifications for parts of software systems. The main goal is to provide specifications sufficiently precise and complete that other pieces of software can be written to interact with the piece specified without additional information. The secondary goal is to include in the specification no more information than necessary to meet the first goal. The technique is illustrated by means of a variety of examples from a tutorial system.
An FPGA-based video compressor for H.263 compatible bit streams
Authors: G. Lienhart, R. Männer, K. H. Noffz, R. Lay
Venue: Proceedings of the 2001 ACM/SIGDA ninth international symposium on Field programmable gate arrays (2001)

This paper presents an FPGA architecture for video encoding according to the H.263 standard for video teleconferencing systems. The implementation is based on an off-the-shelf FPGA1 and is embedded in a PCI plug-in card2 with on-board SRAM plus external SRAM. The most complex part of the H.263 protocol, a base-line encoder, was implemented. The strategies, which have been applied to build the complex encoding operations, are treated in this paper. The complete application is able to operate at 30 MHz. This leads to a maximum compression speed of 120 Mbit/s allowing simultaneous real-time operation of several video streams in a single reconfigurable chip. Enhanced coding options can also become implemented with present-day FPGAs. The use of FPGA technology enables the adaptation of hardware to various protocols and environments by software and therefore saves development time and hardware costs.
Cooking with Linux: A Few Recipes for Easier Firewalls
Authors: Marcel Gagne
Venue: Linux Journal (2000)

This month Marcel writes about how to build firewalls. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Technology mapping for minimizing gate and routing area
Authors: Aiguo Lu, Guenter Stenz, Frank M. Johannes
Venue: Proceedings of the conference on Design, automation and test in Europe (1998)

This paper presents a technology mapping approach for the standard cell technology, which takes into account both gate area and routing area so as to minimize the total chip area after layout. The routing area is estimated using two parameters available at the mapping stage; one is the fanout count of a gate, and the other is the "overlap of fanin level intervals". To estimate the routing area in terms of accurate fanout counts, an algorithm is proposed which solves the problem of dynamic fanout changes in the mapping process. This also enables us to calculate the gate area more accurately. Experimental results show that this approach provides an average reduction of 15% in the final chip area after placement and routing.
Soft ARQ for Layered Streaming Media
Authors: Matthew G. Podolsky, Steven McCanne, Martin Vetterli
Venue: Journal of VLSI Signal Processing Systems (2001)

A growing and important class of traffic in the Internet is so-called &ldquo;streaming media,&rdquo; in which a server transmits a packetized multimedia signal to a receiver that buffers the packets for playback. This playback buffer, if adequately sized, counteracts the adverse impact of delay jitter and reordering suffered by packets as they traverse the network, and if large enough also allows lost packets to be retransmitted before their playback deadline expires. We call this framework for retransmitting lost streaming-media packets &ldquo;soft ARQ&rdquo; since it represents a relaxed form of Automatic Repeat reQuest (ARQ). While state-of-the-art media servers employ such strategies, no work to date has proposed an optimal strategy for delay-constrained retransmissions of streaming media&mdash;specifically, one which determines what is the optimal packet to transmit at any given point in time. In this paper, we address this issue and present a framework for streaming media retransmission based on layered media representations, in which a signal is decomposed into a discrete number of layers and each successive layer provides enhanced quality. In our approach, the source chooses between transmitting (1) newer but critical coarse information (e.g., a first approximation of the media signal) and (2) older but less important refinement information (e.g., added details) using a decision process that minimizes the expected signal distortion at the receiver. To arrive at the proper mix of these two extreme strategies, we derive an optimal strategy for transmitting layered data over a binary erasure channel with instantaneous feedback. To provide a quantitative performance comparison of different transmission policies, we conduct a Markov-chain analysis, which shows that the best transmission policy is time-invariant and thus does not change as the frames' layers approach their expiration times.
Locally X Matrices, Spectral Distributions, Preconditioning, and Applications
Authors: Stefano Serra Capizzano
Venue: SIAM Journal on Matrix Analysis and Applications (2000)

Starting from a set X= {Xn}n of Hermitian positive definite $n\times n$ matrices, we constructively define a class ${\cal LL}(X)$ of "locally X" matrices which can be viewed as the range of a special sequence of linear normally positive operators. Regarding the spectra of these matrices and of the related preconditioned matrices, we prove some Szego-style ergodic formulas. These results allow one to define a very general procedure for devising optimal and superlinear preconditioners. As special cases, we can deal with matrices coming from the discretization of elliptic and semi-elliptic differential equations defined on multidimensional domains as well as matrices coming from optimization problems connected with graph theory.
Algorithm and bound for the greatest common divisor of n integers
Authors: Gordon H. Bradley
Venue: Communications of the ACM (1970)

A new version of the Euclidean algorithm for finding the greatest common divisor of n integers ai and multipliers xi such that gcd = x1 a1 + &middot;&middot;&middot; + xn an is presented. The number of arithmetic operations and the number of storage locations are linear in n. A theorem of Lam&eacute; that gives a bound for the number of iterations of the Euclidean algorithm for two integers is extended to the case of n integers. An algorithm to construct a minimal set of multipliers is presented. A Fortran program for the algorithm appears as Comm. ACM Algorithm 386.
A description of the APT language
Authors: S. A. Brown, C. E. Drayton, B. Mittman
Venue: Communications of the ACM (1963)

The APT (Automatically Programmed Tools) language for numerical control programming is described using the metalinguistic notation introduced in the ALGOL 60 report. Examples of APT usage are included. Presented also are an historical summary of the development of APT and a statement concerning its present status.