ppxscal/embedding_network huggingface dataset:
On the Fourier Properties of Discontinuous Motion
Authors: Steven S. Beauchemin, John L. Barron
Venue: Journal of Mathematical Imaging and Vision (2000)

Retinal image motion and optical flow as its approximation are fundamental concepts in the field of vision, perceptual and computational. However, the computation of optical flow remains a challenging problem as image motion includes discontinuities and multiple values mostly due to scene geometry, surface translucency and various photometric effects such as reflectance. In this contribution, we analyze image motion in the frequency space with respect to motion discontinuities and translucence. We derive the frequency structure of motion discontinuities due to occlusion and we demonstrate its various geometrical properties. The aperture problem is investigated and we show that the information content of an occlusion almost always disambiguates the velocity of an occluding signal suffering from the aperture problem. In addition, the theoretical framework can describe the exact frequency structure of Non-Fourier motion and bridges the gap between Non-Fourier visual phenomena and their understanding in the frequency domain.
Graphical entry of FSMDs revisited: putting graphical models on a solid base
Authors: T. Müller-Wipperfürth, R. Hagelauer
Venue: Proceedings of the conference on Design, automation and test in Europe (1998)

The paper discusses issues of graphical modelling of Finite State Machines with Datapath (FSMDs). Tools supporting the graphical entry of state based systems are usable by intuition, but need to be based on an exact definition of semantics of graphical elements. This paper proposes to define semantics of graphical models based on the hardware description language VHDL.
High performance reactive fluid flow simulations using adaptive mesh refinement on thousands of processors
Authors: A. C. Calder, B. C. Curtis, L. J. Dursi, B. Fryxell, P. MacNeice, K. Olson, P. Ricker, R. Rosner, F. X. Timmes, H. M. Tufo, J. W. Turan, M. Zingale, G. Henry
Venue: Proceedings of the 2000 ACM/IEEE conference on Supercomputing (CDROM) (2000)

We present simulations and performance results of nuclear burning fronts in supernovae on the largest domain and at the finest spatial resolution studied to date. These simulations were performed on the Intel ASCI-Red machine at Sandia National Laboratories using FLASH, a code developed at the Center for Astrophysical Thermonuclear Flashes at the University of Chicago. FLASH is a modular, adaptive mesh, parallel simulation code capable of handling compressible, reactive fluid flows in astrophysical environments. FLASH is written primarily in Fortran 90, uses the Message-Passing Interface library for inter-processor communication and portability, and employs the PARAMESH package to manage a block-structured adaptive mesh that places blocks only where resolution is required and tracks rapidly changing flow features, such as detonation fronts, with ease. We describe the key algorithms and their implementation as well as the optimizations required to achieve sustained performance of 238 GFLOPS on 6420 processors of ASCI-Red in 64 bit arithmetic.
Directed random generation of sentences
Authors: Joyce Friedman
Venue: Communications of the ACM (1969)

The problem of producing sentences of a transformational grammar by using a random generator to create phrase structure trees for input to the lexical insertion and transformational phases is discussed. A purely random generator will produce base trees which will be blocked by the transformations, and which are frequently too long to be of practical interest. A solution is offered in the form of a computer program which allows the user to constrain and direct the generation by the simple but powerful device of restricted subtrees. The program is a directed random generator which accepts as input a subtree with restrictions and produces around it a tree which satisfies the restrictions and is ready for the next phase of the grammar. The underlying linguistic model is that of Noam Chomsky, as presented in Aspects of the Theory of Syntax. The program is written in FORTRAN IV for the IBM 360/67 and is part of a unified computer system for transformational grammar. It is currently being used with several partial grammars of English.
On approaches to the study of social issues in computing
Authors: Abbe Mowshowitz
Venue: Communications of the ACM (1981)

This paper identifies and analyzes technical and nontechnical biases in research on social issues in computing. Five positions&mdash;technicism, progressive individualism, elitism, pluralism, and radical criticism&mdash;which reflect major streams of contemporary social thought are examined. The analysis of positions documents the close relationship between research and policy formation and reveals the misleading and dangerous character of the presumption of scholarly objectivity in research on social issues.
An ALGOL compiler: construction and use in relation to an elaborate operating system
Authors: J. C. Boussard
Venue: Communications of the ACM (1966)

An ALGOL translator has been prepared and integrated into the IBSYS Operating System. Assembly and &ldquo;go&rdquo; features of IBSYS permit immediate execution with optional listings, decks and debugging information. Using the chain feature of IBSYS, links written in MAP or FORTRAN as well as ALGOL may be called by the ALGOL main program. In addition, procedures coded in MAP may be included in any ALGOL program. Although assembly plus loading time exceeds compilation time, the total time is satisfactory and the user gets ease and facility which are fully compensating.
Exploiting Network Locality for CC-NUMA Multiprocessors
Authors: Hung-Chang Hsiao, Chung-Ta King
Venue: The Journal of Supercomputing (2001)

Rapid advances in interconnection networks in multiprocessors are closing the gap between computation and communication. Given this trend, how can we utilize fast interconnects? This study proposes an enhanced CC-NUMA architecture, called Depot-NUMA, which views the congregation of the private caches in all nodes as a large remote access cache. Fast interconnects allow a missing block to be fetched from the private caches of other sharing nodes rather than from the home node. Issues involved in designing Depot-NUMA are also discussed, and a novel routing scheme, called multi-hop, is proposed to communicate between the potential sharers and fetch a missing block from their private caches. The sharers are specified based on a stride function to exploit network locality in the system. The proposed Depot-NUMA design requires only modest modification to the node controller and coherence protocol. Additionally, the interconnect fabric can be constructed using existing and unmodified commodity interconnects. Furthermore, the application-driven study reveals that Depot-Numa can reduce the read stall time by up to 41%percnt; and is competitive compared to a CC-NUMA with a large local cache.
An assistive robotic agent for pedestrian mobility
Authors: Glenn Wasson, Jim Gunderson, Sean Graves, Robin Felder
Venue: Proceedings of the fifth international conference on Autonomous agents (2001)

The goal of this project is to develop a pedestrian mobility aid for the elderly. In order for this type of assistive technology to be useful and accepted by its intended user community, it must enhance the abilities of users, not replace them. This leads to an agent architecture in which the agent must operate without hindering the user's ability to take direct action when they choose. In other words, the agent cannot simply be a proxy for the user's actions. The agent must select its own goals based on observations of its users actions. This is crucial not only because users may have diminished capacity to explain their actions to an agent, but because the ability of the agent to correctly interpret the user's goals is tied to its ability to act while still allowing the user to &ldquo;feel in control&rdquo;. We present a mobility aid, i. e. a wheeled walker, which varies its goals and level of activity based on an estimation of its user's intentions. The assistive agent often takes no action, allowing the user to be fully in control. When the ease or safety of the users travel is threatened, the agent attempts to influence the users motion based on its belief in the users goal. By varying the degree of autonomy, the walker can adjust to the user as their abilities change from day to day, or hour to hour. This prevents the walker from trying to do too much, allowing the user to feel as if they are in control and not being lead.
Towards agent-oriented assistance for framework instantiation
Authors: Alvaro Ortigosa, Marcelo Campo, Roberto Moriyón
Venue: Proceedings of the 15th ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications (2000)

In this work we present a tool for assisting object-oriented framework instantiation based on Intelligent Agent technology. Differently from other approaches, the user is able to select the functionality needed for the new application, and based on this selection an agent elaborates a sequence of programming activities that should be carried out in order to implement it. In addition, the agent guides the execution of the activities according to the framework design. To enable this behavior, the framework need to be documented following the SmartBooks method, which extends traditional framework documentation with instantiation rules. In this paper we present an example of an instantiation environment built based on these ideas and the main characteristics of the SmartBooks method for documenting frameworks through instantiation knowledge rules.
ConNexus to awarenex: extending awareness to mobile users
Authors: John C. Tang, Nicole Yankelovich, James Begole, Max Van Kleek, Francis Li, Janak Bhalodia
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2001)

We explored the use of awareness information to facilitate communication by developing a series of prototypes. The ConNexus prototype integrates awareness information, instant messaging, and other communication channels in an interface that runs on a desktop computer. The Awarenex prototype extends that functionality to wireless handheld devices, such as a Palm. A speech interface also enables callers to make use of the awareness information over the telephone. While the prototypes offer similar functionality, the interfaces reflect the different design affordances and use context of each platform. We discuss the design implications of providing awareness information on devices with varying interface and network characteristics.
A note on the generation of rosary permutations
Authors: Ronald C. Read
Venue: Communications of the ACM (1972)

Harada [1] has given a method of generating rosary permutations, and of associating an integer with each such permutation in a one-to-one manner. In this note we show that both these ends can be achieved more easily than by Harada's method.
Scalable fault-tolerant distributed shared memory
Authors: Florin Sultan, Liviu Iftode, Thu Nguyen
Venue: Proceedings of the 2000 ACM/IEEE conference on Supercomputing (CDROM) (2000)

This paper shows how a state-of-the-art software distributed shared-memory (DSM) protocol can be efficiently extended to tolerate single-node failures. In particular, we extend a home-based lazy release consistency (HLRC) DSM system with independent checkpointing and logging to volatile memory, targeting shared-memory computing on very large LAN-based clusters. In these environments, where global coordination may be expensive, independent checkpointing becomes critical to scalability. However, independent checkpointing is only practical if we can control the size of the log and checkpoints in the absence of global coordination. In this paper we describe the design of our fault-tolerant DSM system and present our solutions to the problems of checkpoint and log management. We also present experimental results showing that our fault tolerance support is light-weight, adding only low messaging, logging and checkpointng overheads, and that our management algorithms can be expected to effectively bound the size of the checkpoints and logs for real applications.
Illumination for computer generated pictures
Authors: Bui Tuong Phong
Venue: Communications of the ACM (1975)

The quality of computer generated images of three-dimensional scenes depends on the shading technique used to paint the objects on the cathode-ray tube screen. The shading algorithm itself depends in part on the method for modeling the object, which also determines the hidden surface algorithm. The various methods of object modeling, shading, and hidden surface removal are thus strongly interconnected. Several shading techniques corresponding to different methods of object modeling and the related hidden surface algorithms are presented here. Human visual perception and the fundamental laws of optics are considered in the development of a shading rule that provides better quality and increased realism in generated images.
Relational agents: a model and implementation of building user trust
Authors: Timothy Bickmore, Justine Cassell
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2001)

Building trust with users is crucial in a wide range of applications, such as financial transactions, and some minimal degree of trust is required in all applications to even initiate and maintain an interaction with a user. Humans use a variety of relational conversational strategies, including small talk, to establish trusting relationships with each other. We argue that such strategies can also be used by interface agents, and that embodied conversational agents are ideally suited for this task given the myriad cues available to them for signaling trustworthiness. We describe a model of social dialogue, an implementation in an embodied conversation agent, and an experiment in which social dialogue was demonstrated to have an effect on trust, for users with a disposition to be extroverts.
Generating efficient plans for queries using views
Authors: Foto N. Afrati, Chen Li, Jeffrey D. Ullman
Venue: ACM SIGMOD Record (2001)

We study the problem or generating efficient, equivalent rewritings using views to compute the answer to a query. We take the closed-world assumption, in which views are materialized from base relations, rather than views describing sources in terms of abstract predicates, as is common when the open-world assumption is used. In the closed-world model, there can be an infinite number of different rewritings that compute the same answer, yet have quite different performance. Query optimizers take a logical plan (a rewriting of the query) as an input, and generate efficient physical plans to compute the answer. Thus our goal is to generate a small subset of the possible logical plans without missing an optimal physical plan. We first consider a cost model that counts the number of subgoals in a physical plan, and show a search space that is guaranteed to include an optimal rewriting, if the query has a rewriting in terms of the views. We also develop an efficient algorithm for finding rewritings with the minimum number of subgoals. We then consider a cost model that counts the sizes of intermediate relations of a physical plan, without dropping any attributes, and give a search space for finding optimal rewritings. Our final cost model allows attributes to be dropped in intermediate relations. We show that, by careful variable renaming, it is possible to do better than the standard &ldquo;supplementary relation&rdquo; approach, by dropping attributes that the latter approach would retain. Experiments show that our algorithm of generating optimal rewritings has good efficiency and scalability.
Handling sporadic tasks in multimedia file system
Authors: Youjip Won, Y. S. Ryu
Venue: Proceedings of the eighth ACM international conference on Multimedia (2000)

Handling mixed workload in streaming server becomes important issue as integrated file system gets momentum as the choice for next generation file system. In this article, we present novel approach of handling sporadically arriving non-playback related disk request while minimizing its interference with the timely retrieval of data blocks for ongoing playbacks. The main idea of our approach is to extend the length of period in period based disk scheduling in multi-media streaming and subsequently a certain fraction of each period can be set aside for handling unexpected I/O request. We develop the analytical model to establish the relationship between the length of period, request arrival rate, request service time, and P(jitter). This model is used to precisely compute the length of period and the respective buffer size. We present the result of simulation based experiment.
Phase Compensation of Ideal Inductances Based Second-Generation Current Conveyors
Authors: Alain Fabre, Omar Saaïd
Venue: Analog Integrated Circuits and Signal Processing (2000)

The equivalent impedance of the conventional ideal inductance implemented from two second-generation current conveyors is firstly calculated taking all the parasitic elements into account. Its equivalent electrical schema, which comprises six components is characterized. It is demonstrated that the most important deviation at high frequencies comes from the phase shifts of the transfers of the conveyors. Compensation of these effects are obtained from the first-order compensation method using a single additive resistor. SPICE simulations using an industrial BiCMOS process are used to demonstrate the validity of this approach. As an example, the current conveyors being DC biased with I_{0} = 100\,\mu \hbox {A} and supplied under \pm2.5 V, an inductance of 0.67 &mu;H was found directly usable without compensation up to about 15 MHz. This frequency range is then extended up to about 100 MHz when the circuit has been compensated from a single resistor of 75 &Omega;.
Hierarchical multi-agent reinforcement learning
Authors: Rajbala Makar, Sridhar Mahadevan, Mohammad Ghavamzadeh
Venue: Proceedings of the fifth international conference on Autonomous agents (2001)

In this paper we investigate the use of hierarchical reinforcement learning to speed up the acquisition of cooperative multi-agent tasks. We extend the MAXQ framework to the multi-agent case. Each agent uses the same MAXQ hierarchy to decompose a task into sub-tasks. Learning is decentralized, with each agent learning three interrelated skills: how to perform subtasks, which order to do them in, and how to coordinate with other agents. Coordination skills among agents are learned by using joint actions at the highest level(s) of the hierarchy. The Q nodes at the highest level(s) of the hierarchy are configured to represent the joint task-action space among multiple agents. In this approach, each agent only knows what other agents are doing at the level of sub-tasks, and is unaware of lower level (primitive) actions. This hierarchical approach allows agents to learn coordination faster by sharing information at the level of sub-tasks, rather than attempting to learn coordination taking into account primitive joint state-action values. We apply this hierarchical multi-agent reinforcement learning algorithm to a complex AGV scheduling task and compare its performance and speed with other learning approaches, including flat multi-agent, single agent using MAXQ, selfish multiple agents using MAXQ (where each agent acts independently without communicating with the other agents), as well as several well-known AGV heuristics like "first come first serve", "highest queue first" and "nearest station first". We also compare the tradeoffs in learning speed vs. performance of modeling joint action values at multiple levels in the MAXQ hierarchy.
A note on the randomness in dynamic threshold schemes
Authors: Carlo Blundo, Barbara Masucci
Venue: Journal of Computer Security (1999)

In dynamic threshold schemes the dealer is able (after a preprocessing stage) to allow sets of participants of a given cardinality to reconstruct different secrets (in different time instants) by sending them the same broadcast message. In this paper we provide a tight lower bound on the number of random bits needed by the dealer to set up a dynamic threshold scheme.
The expanding world of computers
Authors: E. L. Harder
Venue: Communications of the ACM (1968)

The onward sweep of automatic processing of information is impeded by nine principal barriers: geography, cost, problem complexity, man-machine communication, inadequate sensors, lack of understanding, distance, time, and size. The main incentive for breaching these barriers is the universal need for processing information, ever more urgent as the greater part of human work activity changes from production to service. Computer developments in hardware, programming, time-sharing, education, data communication, and displays are judged by how effectively they remove these barriers, and their barrier-smashing potentialities indicate continued rapid expansion. Problem-oriented languages are particularly effective over the entire front. Online computers and time-sharing also rate high by this measure. Education and increased understanding are basic to all progress with the computer. This complex but powerful tool is the most important one available to governments and scientists to use in studying the problems being created by the population explosion, and in analyzing possible solutions.
Multimethod communication for high-performance metacomputing applications
Authors: Ian Foster, Jonathan Geisler, Carl Kesselman, Steven Tuecke
Venue: Proceedings of the 1996 ACM/IEEE conference on Supercomputing (CDROM) (1996)

Metacomputing systems use high-speed networks to connect supercomputers, mass storage systems, scientific instruments, and display devices with the objective of enabling parallel applications to utilize geographically distributed computing resources. However, experience shows that high performance can often be achieved only if applications can integrate diverse communication substrates, transport mechanisms, and protocols, chosen according to where communication is directed, what is communicated, or when communication is performed. In this paper, we describe a software architecture that addresses this requirement. This architecture allows multiple communication methods to be supported transparently in a single application, with either automatic or user-specified selection criteria guiding the methods used for each communication. We describe an implementation of this architecture, based on the Nexus communication library, and use this implementation to evaluate performance issues. This implementation was used to support a wide variety of applications in the I-WAY metacomputing experiment at Supercomputing~95; we use one of these applications to provide a quantitative demonstration of the advantages of multimethod communication in a heterogeneous networked environment.
Homogeneous Routing for Homogeneous Traffic Patterns on Meshes
Authors: L. D. Aronson
Venue: IEEE Transactions on Parallel and Distributed Systems (2000)

The performance analysis of dynamic routing algorithms in interconnection networks of parallel computers has thus far predominantly been done by simulation studies. A limitation of simulation studies is that they usually only hold for specific combinations of network, routing algorithm, and traffic pattern. In this paper, we derive saturation point results for the class of homogeneous traffic patterns and a large class of routing functions on meshes. We show that the best possible saturation point on a mesh is half the best possible saturation point on a torus. We also show that, if we restrict ourselves to homogeneous routing functions, the worst possible saturation point on a mesh is again half the best possible saturation point. Finally, we present a class of homogeneous routing functions, containing the well-known e-cube routing function, which are all optimal for all homogeneous traffic patterns.