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Real-time sonar beamforming on workstations using process networks and POSIX threads

IEEE TRANSACTIONS ON SIGNAL PROCESSING 2000年第3期48卷 921-926页

作者： Allen, GE Evans, BL Univ Texas Appl Res Labs Austin TX 78713 USA Univ Texas Dept Elect & Comp Engn Austin TX 78712 USA

We present a scalable framework for real-time data-intensive systems on commodity multiprocessor workstations. The framework is an extension of the process network model, which captures parallelism, guarantees determinate execution, and executes in bounded memory. We implement the framework using lightweight POSIX threads and prototype a 4-GFLOP sonar beamformer on a 12-processor 336-MHz Sun Enterprise server. The beamformer scales nearly linearly from 1 to 12 processors.

关键词： beamforming high-performance computing models of computation multiprocessor programming native signal processing process networks real-time systems scalable software

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Single source design environment for embedded systems based on SystemC

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DESIGN AUTOMATION FOR EMBEDDED SYSTEMS 2004年第4期9卷 293-312页

作者： Posadas, H Herrera, F Fernández, V Sánchez, P Villar, E Blasco, F Univ Cantabria TEISA Dept ETSI Ind & Telecom Santandar 39005 Spain

There is a clear need for new methodologies supporting efficient design of embedded systems on complex platforms implementing both hardware and software modules. Software development has to be carried out under a closer relationship with the underlying platform. The current trend is towards an increasing embedded software development effort under more stringent time-to-market requirements. As a consequence, it is necessary to reduce software generation cost while maintaining reliability and design quality. In that context, languages centered on describing whole systems, with software and hardware parts, have been proposed. Among these, SystemC is gaining increasing interest as a specification language for embedded systems. SystemC supports the specification of the complete system and the modeling of the platform. In this paper, the application of SystemC to performance analysis and embedded software generation is discussed. A single-source approach is proposed, that is, the use of the same code for system-level specification and profiling, and, after architectural mapping, for HW/SW co-simulation and embedded software generation. A design environment based on C++ libraries for performance analysis and software generation is presented. This approach avoids working on intermediate formats and translators, which facilitates the designer's interaction with the system description throughout the development process. Additionally, it ensures the preservation of the computational models used for the system specification during architectural mapping and compilation.

关键词： SystemC system-level languages performance analysis embedded software models of computation

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A notion of effectiveness for subshifts on finitely generated groups

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THEORETICAL COMPUTER SCIENCE 2017年 661卷 35-55页

作者： Aubrun, Nathalie Barbieri, Sebastian Sablik, Mathieu Univ Lyon UCBL CNRS INRIAENS LyonLIP Lyon France Univ Paul Sabatier Univ Toulouse CNRS Inst Math ToulouseUMR5219 Toulouse France

We generalize the classical definition of effectively closed subshift to finitely generated groups. We study classical stability properties of this class and then extend this notion by allowing the usage of an oracle to the word problem of a group. This new class of subshifts forms a conjugacy class that contains all sofic subshifts. Motivated by the question of whether there exists a group where the class of sofic subshifts coincides with that of effective subshifts, we show that the inclusion is strict for several groups, including recursively presented groups with undecidable word problem, amenable groups and groups with more than two ends. We also provide an extended model of Turing machine which uses the group itself as a tape and characterizes our extended notion of effectiveness. As applications of these machines we prove that the origin constrained domino problem is undecidable for any group of the form G x Z subject to a technical condition on G and we present a simulation theorem which is valid in any finitely generated group. (C) 2016 Elsevier B.V. All rights reserved.

关键词： Symbolic dynamics Turing machines Word problems models of computation

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First and second order recursion on abstract data types

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FUNDAMENTA INFORMATICAE 2005年第4期67卷 377-419页

作者： Xu, J Zucker, J McMaster Univ Dept Comp & Software Hamilton ON L8S 4L7 Canada

This paper compares two scheme-based models of computation on abstract many-sorted algebras A: Feferman's system ACP(A) of "abstract computational procedures" based on a least fixed point operator, and Tucker and Zucker's system mu PR(A) based on primitive recursion on the naturals together with a least number operator. We prove a conjecture of Feferman that (assuming A contains sorts for natural numbers and arrays of data) the two systems are equivalent. The main step in the proof is showing the equivalence of both systems to a system Rec(A) of computation by an imperative programming language with recursive calls. The result provides a confirmation for a Generalized Church-Turing Thesis for computation on abstract data types.

关键词： models of computation many-sorted algebras recursive schemes recursive procedures fixed points computation on abstract data types abstract computability

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Design, Realization, and Evaluation of uDirect - An Approach for Pervasive Observation of User Facing Direction on Mobile Phones

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IEEE TRANSACTIONS ON MOBILE COMPUTING 2014年第9期13卷 1981-1994页

作者： Hoseinitabatabaei, Seyed Amir Gluhak, Alexander Tafazolli, Rahim Headley, William Univ Surrey Ctr Commun Syst Res Dept Elect Engn Guildford GU2 7YW Surrey England

A novel method for a mobile phone centric observation of a user's facing direction is presented. To estimate this direction, our proposed technique exploits the acceleration pattern that can be measured by a smartphone as the user is walking. For an accurate analysis of the acceleration pattern, the proposed approach benefits from a new trigonometric interpolation scheme. Our algorithm is independent of the initial orientation of the device and is adaptable to various wearing positions on a user's body, which gives the user a larger degree of freedom. A detailed description of the algorithm, which has been customized for a trouser pocket is presented. In addition, complementary hints for adaptation of the algorithm to other wearing positions along with an example of chest pocket position are provided. We have evaluated a prototype implementation of our algorithm on a smartphone, through several field experiments. It has been observed that our algorithm outperforms the conventional GPS and PCA-based techniques in terms of accuracy, reliability and energy consumption. The results also show that our approach has been able to handle the sudden variations of the user's direction. We have further incorporated our algorithm into a dead-reckoning application as an example of its real-world utility.

关键词： Pervasive computing mobile phone based sensing models of computation walking locomotion

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ForSyDe-Atom: Taming Complexity in Cyber Physical System Design with Layers

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ACM TRANSACTIONS ON EMBEDDED COMPUTING SYSTEMS 2021年第2期20卷 1-27页

作者： Ungureanu, George De Medeiros, Jose Edil Guimaraes Sundstrom, Timmy Soderquist, Ingemar Ahlander, Anders Sander, Ingo KTH Royal Inst Technol Sch Elect Engn & Comp Sci Div Elect & Embedded Syst Kistagangen 16 Kista Sweden Univ Brasilia Fac Tecnol Dept Engn Elect Campus Univ Darcy Ribeiro Ed Brasilia DF Brazil Saab AB Business Area Aeronaut SE-58188 Linkoping Sweden Saab AB Business Area Surveillance SE-41289 Gothenburg Sweden

We present ForSyDe-Atom, a formal framework intended as an entry point for disciplined design of complex cyber-physical systems. This framework provides a set of rules for combining several domain-specific languages as structured, enclosing layers to orthogonalize the many aspects of system behavior, yet study their interaction in tandem. We define four layers: one for capturing timed interactions in heterogeneous systems, one for structured parallelism, one for modeling uncertainty, and one for describing component properties. This framework enables a systematic exploitation of design properties in a design flow by facilitating the stepwise projection of certain layers of interest, the isolated analysis and refinement on projections, and the seamless reconstruction of a system model by virtue of orthogonalization. We demonstrate the capabilities of this approach by providing a compact yet expressive model of an active electronically scanned array antenna and signal processing chain, simulate it, validate its conformity with the design specifications, refine it, synthesize a sub-system to VHDL and sequential code, and co-simulate the generated artifacts.

关键词： Cyber-physical systems system design language models of computation design methodology modeling simulation validation synthesis

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On the complexity analysis of static analyses

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JOURNAL OF THE ACM 2002年第4期49卷 512-537页

作者： Mcallester, D AutoReason Com New Providence NJ 07975 USA

This paper argues that for many algorithms, and static analysis algorithms in particular, bottom-up logic program presentations are clearer and simpler to analyze, for both correctness and complexity, than classical pseudo-code presentations. The main technical contribution consists of two theorems which allow, in many cases, the asymptotic running time of a bottom-up logic program to e determined by inspection. It is well known that a datalog program runs in O(n(k)) time where k is the largest number of free variables in any single rule. The theorems given here are significantly more refined. A variety of algorithms are presented and analyzed as examples.

关键词： algorithms languages theory algorithms complexity analysis logic programming models of computation program analysis programming languages

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Unconventional Wisdom: Superlinear Speedup and Inherently Parallel computations

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INTERNATIONAL JOURNAL OF UNCONVENTIONAL COMPUTING 2018年第4-5期13卷 283-307页

作者： Akl, Selim G. Queens Univ Sch Comp Kingston ON K7L 3N6 Canada

A number of unconventional computational problems are described in which parallelism plays a fundamental role. These problems highlight two recently uncovered aspects of parallel computation: 1. There exist computations for which the running time of a parallel algorithm, compared to that of the best sequential algorithm, shows a speedup that is superlinear in the number of processors used, a feat that was previously believed to be impossible. 2. There exist inherently parallel computations, that is, computations that can be carried successfully in parallel, but not sequentially. A surprising consequence of these discoveries is that the concept of universality in computation, long held as a basic truth, is in fact false.

关键词： models of computation inherently parallel computations unconventional computations superlinear speedup superlinear slowdown universality

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Quantum computation: From a Programmer's Perspective

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NEW GENERATION COMPUTING 2013年第1期31卷 1-26页

作者： Valiron, Benoit Univ Penn Dept Comp & Informat Sci Philadelphia PA 19104 USA

This paper is the second part of a series of two articles on quantum computation. If the first part was mostly concerned with the mathematical formalism, here we turn to the programmer's perspective. We analyze the various existing models of quantum computation and the problem of the stability of quantum information. We discuss the needs and challenges for the design of a scalable quantum programming language. We then present two interesting approaches and examine their strengths and weaknesses. Finally, we take a step back, and review the state of the research on the semantics of quantum computation, and how this can help in achieving some of the goals.

关键词： Quantum computation models of computation Quantum Programming Language Semantics

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SORTING ON PRAMS WITH RECONFIGURABLE BUSES

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INFORMATION PROCESSING LETTERS 1992年第4期42卷 203-208页

作者： VAIDYANATHAN, R Dep. Electr. and Comp. Eng. Louisiana State Univ. Baton Rouge LA 70803-5901 USA

We propose a new model of computation called the B-PRAM, which is a PRAM augmented with reconfigurable buses that provide additional channels of communication. The B-PRAM is discussed further in the next section. We prove that the OR of n bits can be computed on an EREW B-PRAM in O(1) time, thus showing that the addition of reconfigurable buses makes the model strictly more powerful than the CREW PRAM.

关键词： computationAL COMPLEXITY models of computation PARALLEL ALGORITHMS PARALLEL RANDOM ACCESS MACHINES RECONFIGURABLE BUS SYSTEMS SORTING

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