ppxscal/embedding_network huggingface dataset:
Symmetry in Distributed Systems
Authors: Ralph E. Johnson
Venue:  (1987)

A distributed computing system can be considered to be symmetric because of its topology or because of its behavior. Unfortunately, these different definitions can categorize the same system differently. The choice of definition becomes important when one is trying to prove that certain problems, such as the Dining Philosophers problem, cannot be solved on symmetric distributed computing systems. Since the behavioral definitions are based on the possible patterns of computation, it is much easier to use them for these proofs. However, behavioral definitions admit straightforward decision procedures. This thesis presents a new definition for symmetry, called similarity, that, while based on behavior of processes, is decidable given the initial configuration of the system. The decision procedure for similarity depends partly on the model of computation being used, but a way to discover these decision procedures is given and is used to find decision procedures for a wide range of models of distributed computation. Distributed versions of these decision procedures form the basis of solutions to the problem of selecting a process as the leader. The thesis also shows how to use similarity to compare the relative power of different models of computation, including models with shared variables with and without locking, models using synchronous and asynchronous message-passing, models making different assumptions about fairness, and models based on probabilistic techniques.
Functional Programming Formalisms for OODB Methods
Authors: Gerd Hillebrand, Paris Kanellakis, Sridhar Ramaswamy
Venue:  (1994)

Two well-studied functional formalisms in the theory of programming languages are (1) applicative program schemas and (2) typed lambda calculi. We relate these programming formalisms to object-oriented databases (OODBs) and in particular to the description of methods. The language of method schemas (MS) is a programming formalism based on applicative program schemas with additional key object-oriented features such as classes, methods, inheritance, name overloading, and late binding. From [AKRW92], we present its syntax and semantics and survey the state-of-the-art of consistency checking or signature inference for this language, a problem which can be used in studyingbase schema evolution. We then relate MS with more conventional database query languages by showing that its expressive power over finite ordered databases is PTIME. Despite its simplicity and applicability, MS does not directly model the tuple, set, and list complex structures that are quite common in databases. Also, it does not treat functions as objects, i.e., methods are different from objects. It is possible to achieve these two capabilities using the typed lambda calculus with equality as a database query language, even without any object-oriented features. From [HKM93], we illustrate how this pure functional language subsumes most conventional database query languages including the relational calculus/algebra, Datalog (with or without negation), and the complex object calculus/algebra (with or without powerset). In conclusion, we argue that the appropriate programming formalism for OODBs must be a functional language that combines the object-oriented MS with the expressive $TLC^=$ and facilitates operations on sets of objects.
Visualizing the results of multimedia Web search engines
Authors: S. Mukherjea, K. Hirata, Y. Hara
Venue: Proceedings of the 1996 IEEE Symposium on Information Visualization (INFOVIS '96) (1996)

Search engines are very useful because they allow the user to retrieve documents of interest from the World-Wide Web. However, if the user's query results in lots of records to be retrieved, just listing the results is not very user-friendly. We are developing a system that allows the visualization of the results. Visualizations of both text and image search are generated on the fly based on the search results.
Optimal Video Replication and Placement on a Cluster of Video-on-Demand Servers
Authors: Xiaobo Zhou, Cheng-Zhong Xu
Venue: Proceedings of the 2002 International Conference on Parallel Processing (2002)

A cost-effective approach to building up scalable Video-on-Demand (VoD) servers is to couple a number of VoD servers together in a cluster. In this article, we study a crucial video replication and placement problem in a distributed storage VoD cluster for high quality and high availability services. We formulate it as a combinatorial optimization problem with objectives of maximizing the encoding bit rate and the number of replicas of each video and balancing the workload of the servers. It is subject to the constraints of the storage capacity and the outgoing network bandwidth of the servers. Under the assumption of single fixed encoding bit rate for all videos, we give an optimal replication algorithm and a bounded placement algorithm for videos with different popularities. To reduce the complexity of the replication algorithm, we present an efficient algorithm that utilizes the Zipf-like video popularitydistributions to approximate the optimal solution. For videos with scalable encoding bit rates, we propose a heuristic algorithm based on simulated annealing. We conduct a comprehensive performance evaluation of the algorithms and demonstrate their effectiveness via simulations over a synthetic workload set.
Frechet Differentiability with respect to Lipschitz Domain and a Stability Estimate for Direct Acoustic Scattering Problems
Authors: Rabia Djellouli, Charbel Farhat, Jan Mandel, Petr Vanek
Venue:  (1998)

We consider direct acoustic scattering problems with either a sound-soft or sound-hard obstacle, or lossy boundary conditions, and establish continuous Frechet differentiability with respect to the shape of the scatterer of the scattered field and its corresponding far-field pattern. Our proof is based on the Implicit Function Theorem, and assumes that the boundary of the scatterer as well as the deformation are only Lipschitz continuous. From continuous Frechet differentiability, we deduce a stability estimate governing the variation of the far-field pattern with respect to the shape of the scatterer. We illustrate this estimate with numerical results obtained for a two-dimensional high-frequency acoustic scattering problem.
Computer Science for the Many
Authors: W A Biermann
Venue:  (1991)

\indent A large fraction of all university students come to the computer science department and take just one course. This paper argues that the one course will maximally benefit those people if it teaches the fundamental principles of the field. Specifically, they should be taught some programming and the solution of typical applications, the principles of computer hardware and software, and advanced topics with emphasis on understanding the limitations of the field. They should learn these topics by doing appropriate exercises on each topic: writing programs, designing switching circuits, hand simulating architectures, hand simulating a compiler, studying the execution time of programs and learning to judge tractability and intractability, studying proofs of noncomputability and learning to judge computability and noncomputability, and hand simulating artificial intelligence systems. This paper will discuss how such material can be taught to a general university population and offer evidence that it can be done successfully.
A formal specification language for agent-oriented software engineering
Authors: Hong Zhu
Venue: Proceedings of the second international joint conference on Autonomous agents and multiagent systems (2003)

This paper reports a formal specification language SLABS for developing multi-agent systems. One of the most appealing features of agent technology is its natural way to modularise complex systems in terms of multiple interacting autonomous components. This feature is supported by the language facility castes in the formal specification language SLABS for modular and composable specification of multi-agent systems.
Online learning and adaptation for intelligent embedded agents operating in domestic environments
Authors: Hani Hagras, Victor Callaghan, Martin Colley, Graham Clarke, Hakan Duman
Venue: Autonomous robotic systems: soft computing and hard computing methodologies and applications (2003)

In this chapter we show how intelligent embedded agents situated in an intelligent domestic environment can perform learning and adaptation. A typical domestic environment provides an environment where there is wide scope for utilising computer-based products to enhance living conditions. Intelligent embedded agents can be part of the building infrastructure and static in nature (e,g. lighting, HVAC etc.), some will be carried on the person as wearables, others will be highly mobile, as with robots. Both non-intrusive and interactive learning modes (including a mix of both) are used, depending on situation of the agent. For instance mobile robotic agents use an interactive learning whilst most building based agents use non-intrusive background learning modes. In this chapter we will introduce the learning and adaptation mechanisms needed by the Building and Robotic embedded agents to fulfil their missions in intelligent domestic environments. We also present a high-level multi embedded-agent model, explaining how it facilitates inter-agent communication and cooperation between heterogeneous sets of embedded agents within a domestic environment.
Finite element approximation of piezoelectric plates
Authors: Ferdinando Auricchio, Paolo Bisegna, Carlo Lovadina
Venue:  (1999)

A Reissner-Mindlin-type modelization of piezoelectric plates is here considered in a suitable variational framework. Both the membranal and the bending behaviour are studied as the thickness of the structure tends to zero. A finite element scheme able to approximate the solution is then proposed and theoretically analysed. Some numerical results showing the performances of the scheme under consideration are discussed. EMAIL:: lovadina@ing.unitn.it
The complexity of multiagent systems: the price of silence
Authors: Zinovi Rabinovich, Claudia V. Goldman, Jeffrey S. Rosenschein
Venue: Proceedings of the second international joint conference on Autonomous agents and multiagent systems (2003)

In this work, we suggest representing multiagent systems using computational models, choosing, specifically, Multi-Prover Interactive Protocols to represent agent systems and the interactions occurring within them. This approach enables us to analyze complexity issues related to multiagent systems. We focus here on the complexity of coordination and study the possible sources of this complexity. We show that there are complexity bounds that cannot be lowered even when approximation techniques are applied.
A prototype infrastructure for distributed robot-agent-person teams
Authors: Paul Scerri, David Pynadath, Lewis Johnson, Paul Rosenbloom, Mei Si, Nathan Schurr, Milind Tambe
Venue: Proceedings of the second international joint conference on Autonomous agents and multiagent systems (2003)

Effective coordination of robots, agents and people promises to improve the safety, robustness and quality with which shared goals are achieved by harnessing the highly heterogeneous entities' diverse capabilities. Proxy-based integration architectures are emerging as a standard method for coordinating teams of heterogeneous entities. Such architectures are designed to meet imposing challenges such as ensuring that the diverse capabilities of the group members are effectively utilized, avoiding miscoordination in a noisy, uncertain environment and reacting flexibly to changes in the environment. However, we contend that previous architectures have gone too far in taking coordination responsibility away from entities and giving it to proxies. Our goal is to create a proxy-based integration infrastructure where there is a beneficial symbiotic relationship between the proxies and the team members. By leveraging the coordination abilities of both proxies and socially capable team members the quality of the coordination can be improved. We present two key new ideas to achieve this goal. First, coordination tasks are represented as explicit roles, hence the responsibilities not the actions are specified, thus allowing the team to leverage the coordination skills of the most capable team members. Second, building on the first idea, we have developed a novel role allocation and reallocation algorithm. These ideas have been realized in a prototype software proxy architecture and used to create heterogeneous teams for an urban disaster recovery domain. Using the rescue domain as a testbed, we have experimented with the role allocation algorithm and observed results to support the hypothesis that leveraging the coordination capabilities of people can help the performance of the team.
Dynamic Coding Technique For Low-Power Data Bus
Authors: M. Madhu, V. Srinivasa Murty, V. Kamakoti
Venue: Proceedings of the IEEE Computer Society Annual Symposium on VLSI (ISVLSI'03) (2003)

Designing chips for lower power applications is one ofthe most important challenges faced by the VLSI designers.Since the power consumed by I/O pins of a CPU is a significant source of power consumption, work has been doneon developing encoding schemes for reducing switching activity on external buses. In this paper, we propose a newcoding technique, namely, the Dynamic Coding Scheme,for low-power data bus. Our method considers two logical groupings of the bus lines, each being a permutation ofthe bus lines, and dynamically selects that grouping whichyields the minimum number of transitions.
Hardware Implementation of a PCA Learning Network by an Asynchronous PDM Digital Circuit
Authors: Yuzo Hirai, Kuninori Nishizawa
Venue: Proceedings of the IEEE-INNS-ENNS International Joint Conference on Neural Networks (IJCNN'00)-Volume 2 - Volume 2 (2000)

We have fabricated a PCA (Principal Component Analysis) learning network in a FPGA (Field Programmable Gate Array) b y using an asynchronous PDM (Pulse Density Modulation) digital circuit. The generalized Hebbian algorithm is expressed in a set of ordinary differential equations and the circuits solve them in a parallel and continuous manner. A network with two-microphone inputs and two-speaker outputs tested the performance of the circuits. By moving a sound source right and left in front of the microphones, the first principal weight vector could continuously track the sound direction in real time.
Epochs
Authors: Jon A. Solworth
Venue:  (1987)

To date, the implementation of message passing languages have required the communications variables (sometimes called ports) either to be limited to the number of physical communications registers in the machine, or to be mapped to memory. Neither solution is satisfactory. Limiting the number of variables decreases modularity and efficiency of parallel programs. Mapping variables to memory increases the cost of communications and the granularity of parallelism. We present here a new programming language construct called epochs. Epochs are a scoping mechanism within which the programmer can declare communications variables, which are live only during the scope of that epoch. To limit the range of time a register has to be allocated for a communications variable, the compiler ensures that all processors enter an epoch simultaneously. The programming style engendered fits somewhere between the SIMD data parallel and MIMD process spawning models. We describe an implementation for epochs including an efficient synchronization mechanism, means of statically binding registers to communications variables and a method of fusing epochs to reduce synchronization overhead.
Titan II: An IPComp Processor for 10Gbit/sec networks
Authors: Ioannis Papaefstathiou
Venue: Proceedings of the IEEE Computer Society Annual Symposium on VLSI (ISVLSI'03) (2003)

As it has already been proved, link layer compression isvery effective when used in packet networks. In particular,IP payload compression is especially useful when encryptionis applied to the network packets. Encrypting the IPpackets causes the data to be random in nature, renderingcompression at lower protocol layers. As a result, and sinceit is believed encryption will be applied to the vast majorityof IP networks in the near future, we claim that an IPpacket compressor will be required for taking full advantageof the capabilities of the future networks. However one of themajor problems with such network compression schemes, isthat there should exist hardware modules capable of compressingthe network streams up to the speed of the state-of-the-art links. In this paper we present such a hardwarecompressor/decompressor core that can work at speeds upto 10Gb/sec, it is fairly inexpensive and can very easily beplugged into an existing network node without causing anyside effects. The presented design can be easily incorporatedin a network System-on-a-Chip(Soc).
A Game-Theoretic Approach to the Socialization of Utility-Based Agents
Authors: A. Cunha, J. Neves
Venue: Proceedings of the 3rd International Conference on Multi Agent Systems (1998)

This paper presents a formal framework in which to study the socialization processes evolving among utility-based agents. These agents are self-interested, being their different social attitudes (cooperativeness, competitiveness or indifference) a consequence of this behavior. The dynamics of the socialization process are captured by a relation that measures the similarities between the desires of two groups of agents. This similitude relation is derived from the system's model, defined as a probabilistic transition system and a set of individual preference relations. Game-theoretic concepts are used in order to determine the rational (or expected) transitions of the system.
TACK: a program coupling chemical kinetics with a two-dimensional transport model in geochemical systems
Authors: Göran Källvenius, Christian Ekberg
Venue: Computers Geosciences (2003)

The Transport And Chemical Kinetics (TACK) program has been designed to make predictions of the chemistry in the vicinity of a planned repository for nuclear waste, i.e. SFL 3-5, where SFL is the Swedish abbreviation for "Swedish repository for long-lived waste". This implies modelling transport and chemistry in fractured rock. The system concerned in the modelling of SFL is leaching water from decommissioning waste in concrete. The concrete will raise the pH in the water to between 12 and 13.5. So far, only a few calculations have been made on such systems. Coupled transport and chemical reaction programs should be used, since the system is important for safety assessments of the repository.At least two of programs can be used for this kind of problem, for example OS3D/GIMRT and PHAST. As it is also important to consider the uncertainty of the model, the TACK program fills an important purpose here. A slightly different approach to the problem may give significantly different results. Because validation is generally not possible, using several programs is the only key to identifying conceptual uncertainties. To illustrate this point, comparative calculations have been made between TACK and the PHAST program. The calculations gave qualitatively similar result but quantitatively somewhat differing results.The TACK program couples the well known PHREEQC geochemical program with a two-dimensional transport model. The PHREEQC calculations include speciation of solutions and mineral reactions involving kinetics. The reasons for choosing this program are that it is quite a general one and is relatively stable at the high pH values present in the systems used. The transport phenomena taken into account in the model are advection, diffusion and dispersion in two dimensions.
An Iterative Substructuring Method for Coupled Fluid-Solid Acoustic Problems
Authors: J. Mandel
Venue:  (2000)

A fast parallel iterative method is proposed for the solution of linear systems arizing from Finite Element discretization of the time harmonic acoustics of coupled fluid-solid systems in fluid pressure and solid displacement formulation. The method generalizes the FETI-H method for the Helmholtz equation to elastic scattering. The fluid and the solid domains are decomposed into non-overlapping subdomains. Continuity of the solution is enforced by Lagrange multipliers. The system is augmented by duplicating the degrees of freedom on the wet interface. The original degrees of freedom are then eliminated and the resulting system is solved by the GCR method preconditioned by a subspace correction. In each iteration, the method requires the solution of one independent acoustic problem per subdomain, and the solution of a coarse problem with several degrees of freedom per subdomain. Computational results show that the method is scalable with the problem size, frequency, and the number of subdomains. The number of iterations was mostly about the same as the number of iterations of the FETI-H method for the related Helmholtz problem with Neumann boundary condition instead of elastic scatterer. Convergence is explained from the spectrum of the iteration operator. 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
Pushing the Limits of Transparency in Distributed File Systems
Authors: Rick Floyd, S C Ellis
Venue:  (1991)

\indent The last few years have seen an explosion in the research and development of distributed file systems, and an accompanying increase in user dependence on remotely stored files. Network transparency has become a major theme in this area. Full network transparency implies not only that the file system interface and naming present the appearance of a single file system, but also that the behavior of the system does not betray its distribution. Existing systems provide only a limited degree of network transparency. While full transparency promises advantages such as automatic reconfiguration, increased availability, effective use of resources, and a simplified file system model, there are arguments about its inherent costs and questions about scalability. Attempts to address these concerns have been limited by a lack of understanding of the range of possible solutions to transparency issues. We have designed and implemented a prototype of a highly transparent distributed file system to explore the feasibility of full network transparency. Our distributed file system, Casper, supports a substantially higher degree of network transparency than earlier systems, and is able to do this in a heterogeneous environment. Casper appears to users as a single, globally accessible file system providing highly available, consistent files. Casper uses a name space that is decoupled from the file systems of the hosts supporting it. This allows Casper to provide a coherent framework for uniting techniques in the areas of naming, replication, consistency control, file and directory placement, and file and directory migration in a way that provides full network transparency. In this paper, we present the design of the Casper file system and describe our experiences (both positive and negative) with the implementation.