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Sharing sense of walking with locomotion interfaces

INTERNATIONAL JOURNAL OF HUMAN-computer INTERACTION 2004年第4期17卷 447-462页

作者： Yano, H Kasai, K Saito, H Iwata, H Univ Tsukuba Inst Engn Mech & Syst Tsukuba Ibaraki 3058573 Japan Hitachi Ltd Syst Dev Lab Hitachi Ibaraki Japan Tsukuba Mem Hosp Tsukuba Ibaraki Japan

This article proposes a method of enabling users to share the sensation of walking with each other in a virtual environment (VE). Achieving this shared sensation requires physical equipment, with algorithms to control it. As an example of such physical equipment, a new footpad type of locomotion interface (LI), named GaitMaster2, has been developed and physiologically evaluated. An algorithm for the positional control of users' feet has been proposed, enabling the users to share various aspects of the sensation of walking. As an evaluation, two footpad type LIs were connected via a network. Using the proposed control algorithm, there followed the construction of a master-slave walking environment and a synchronized walking environment. These experiments demonstrated that this method is effective for sharing the sensation of walking in a VE.

关键词： Sensation walking algorithms Position control Footpad Locomotion computer algorithms

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Reducing non-determinism in right nulled GLR parsers

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ACTA INFORMATICA 2004年第6-7期40卷 459-489页

作者： Scott, E Johnstone, A Univ London Royal Holloway & Bedford New Coll Dept Comp Sci Egham TW20 0EX Surrey England

Tomita's general parsing algorithm is linear on LR(1) grammars but fails to terminate on grammars with hidden left recursion and is not efficient in the presence of epsilon-rules. When Right Nulled (RN) parse tables are used Tomita style GLR algorithms operate correctly and more efficiently on all context free grammars. However, an RN table may contain more conflicts than the corresponding LR table, making the construction of parts of the internal structure redundant. We show that in certain cases conflicts can be removed from an RN table without compromising the correctness of the associated parser. In particular, all conflicts can be removed if the grammar is LR(1). This improves the performance of the parser and allows resolved RN tables for LR(1) grammars to be used with standard (deterministic) LR stack-based parsing algorithms, adding the 'short-circuiting' of right nullable reductions to the armoury of efficient implementation techniques for such algorithms.

关键词： PARSING (computer grammar) computer programming ARTIFICIAL languages computer algorithms COMPUTATIONAL linguistics

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Optimal control for bouncing suppression of CNG injectors

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JOURNAL OF DYNAMIC SYSTEMS MEASUREMENT AND CONTROL-TRANSACTIONS OF THE ASME 2004年第1期126卷 47-53页

作者： Dyntar, D Guzzella, L Swiss Fed Inst Technol Zurich Switzerland

This paper describes the model-based design and the experimental validation of a control system which suppresses the bouncing behavior of Compressed Natural Gas (CNG) fuel injectors. First a detailed model of the system is developed, including temperature and supply-voltage variation effects. Using an optical position sensor this model is experimentally validated in a second step. Based on this model a feed-forward controller is developed and tested which minimizes the bouncing energy of the system. Since in series applications position sensing would be too expensive to use, an observer-based iterative control algorithm is derived which uses coil current measurements instead of the position information to asymptotically suppress bouncing.

关键词： control systems Optimal control POSITION INFORMATION ENERGY SYSTEMS jet device Compressed natural gas(CNG) injectors position sensor Bouncing asymptotic computer algorithms

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Compact routing schemes for dynamic ring networks

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THEORY OF COMPUTING SYSTEMS 2004年第5期37卷 585-607页

作者： Krizanc, D Luccio, FL Raman, R Wesleyan Univ Dept Math Middletown CT 06459 USA Univ Trieste Dipartimento Sci Matemat I-34127 Trieste Italy Univ Leicester Dept Math & Comp Sci Leicester LE1 7RH Leics England

We consider the problem of routing in an asynchronous dynamically changing ring of processors using schemes that minimize the storage space for the routing information. In general, applying static techniques to a dynamic network would require significant re-computation. Moreover, the known dynamic techniques applied to the ring lead to inefficient schemes. In this paper we introduce a new technique, Dynamic Interval Routing, and we show tradeoffs between the stretch factor, the adaptation cost, and the size of the update messages used by routing schemes based upon it. We give three algorithms for rings of maximum size N: the first two are deterministic, one with adaptation cost zero but worst case stretch factor [N/2], the other with worst case adaptation cost O (N) update messages of 0 (log N) bits and stretch factor 1. The third algorithm is randomized, uses update messages of size O (k log N), has adaptation cost O (k), and expected stretch factor 1+1/k, for any integer kgreater than or equal to3. All schemes require O (log N) bits per node for the routing information and all messages headers are of O (log N) bits.

关键词： computer algorithms computer programming algorithms computer systems ROUTING-machines ELECTRONIC systems

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Minimum-time spacecraft maneuver using sliding-mode control

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ACTA ASTRONAUTICA 2004年第1期54卷 69-75页

作者： Jan, YW Chiou, JC Natl Chiao Tung Univ Dept Elect & Control Engn Hsinchu 30010 Taiwan

The purpose of this paper is to present a sliding mode control method that can be used to perform a spacecraft large angle maneuver with minimum time. An algorithm of minimum-time SMC is developed to provide the robust tracking control. The simulation results are compared with previous developed control schemes, eigenaxis quaternion regulator, to demonstrate the superiority of the proposed sliding mode control algorithm. (C) 2003 Elsevier Ltd. All rights reserved.

关键词： Simulation results Quaternion algorithms tracking control Spacecraft Variable structure systems Regulators Control Methods computer algorithms

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Hardware-software design and validation framework for wireless LAN modems

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IEE PROCEEDINGS-computerS AND DIGITAL TECHNIQUES 2004年第3期151卷 173-182页

作者： Drosos, C Bisdounis, L Metafas, D Blionas, S Tatsaki, A Papadopoulos, G INTRACOM SA GR-19002 Athens Greece Univ Patras Dept Elect & Comp Engn Appl Elect Lab Patras 26500 Greece

The implementation and validation of a 5-GHz wireless LAN modem based on the HIPERLAN/2 standard is presented. In modern wireless communication systems, there is a demand for higher flexibility and more computational efficiency. Therefore the emphasis of this work is on the hardware-software structure of the developed modem and its processes, in order to offer a good balance of these requirements. In order to efficiently design and validate the behaviour of the modem, a behavioural model was developed in UML (Unified Modelling Language) as a part of the overall HIPERLAN/2 system's model. The processes of the modem were implemented in an instruction-set processor and custom hardware, combining the advantages of both software and hardware implementations. The communication between the software and hardware parts of the modem is achieved through a specialised programmable interface unit. The UML-based model of the actual HIPERLAN/2 system is used in order to validate the modem's behaviour, using scenarios from in-field usage (such as transfer of data using FTP or HTTP). Furthermore, the validation of the algorithms implemented within the modem was based on this system model, and performed through the use of a custom-validation framework. This framework produces patterns for the validation of the modem's algorithms, at three different development phases (algorithmic, HDL, FPGA-based prototyping), derived from the simulation of the system model in a consistent and automatic way. Implementation figures and co-simulation results for the developed wireless LAN modem are also given.

关键词： MODEMS WIRELESS LANs DATA transmission systems computer algorithms MODULATORS (Electronics) ELECTRONICS ELECTRONIC systems

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Extra processors versus future information in optimal deadline scheduling

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THEORY OF COMPUTING SYSTEMS 2004年第3期37卷 323-341页

作者： Koo, CY Lam, TW Ngan, TW To, KK Univ Maryland Dept Comp Sci College Pk MD 20742 USA Univ Hong Kong Dept Comp Sci Hong Kong Hong Kong Peoples R China Rice Univ Dept Comp Sci Houston TX 77005 USA

This paper is concerned with the design of online scheduling algorithms that exploit extra resources. In particular, it studies how to make use of multiple processors to counteract the lack of future information in online deadline scheduling. Our results extend the previous work that are primarily based on using a faster,processor to obtain a performance guarantee. The challenge arises from the fact that jobs are sequential in nature and cannot be executed on more than one processor at the same time. Thus, a faster processor can speed up a job while multiple unit-speed processors cannot.

关键词： PRODUCTION scheduling ONLINE algorithms ONLINE data processing computer algorithms ELECTRONIC data processing OPERATIONS research

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Protocol converter synthesis

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IEE PROCEEDINGS-computerS AND DIGITAL TECHNIQUES 2004年第6期151卷 391-401页

作者： Androutsopoulos, V Brookes, DM Clarke, TJW Univ London Imperial Coll Sci Technol & Med Dept Elect & Elect Engn London SW7 2BT England

A system-on-a-chip is an interconnection of different pre-verified IP hardware blocks, which communicate using complex protocols. The integration of IP blocks requires some glue logic to interface otherwise incompatible datapaths. This glue logic is called a protocol converter and its manual design proves to be a tedious and time-consuming task. Automatic synthesis is therefore important, but for optimal system-level design it is necessary to consider not just the correctness, but also the quality (in terms of bandwidth and latency of data transfer) of the converter. A good solution to this problem will allow greater use of protocol-level abstraction as a design tool in system design and synthesis. Results are presented on automatic synthesis of a converter between two protocols. It is shown how converter logic which is bandwidth-optimal can be synthesised for datapaths with an arbitrary number of data ports each of which has arbitrary-size first-in first-out (FIFO) storage. An extension of the product FSM converter synthesis algorithm to include FIFO data-paths is presented. In addition the converter bandwidth is identified as a mean cycle graph problem which is solved using maximum mean cycle graph algorithms.

关键词： computer network protocols computer networks STANDARDS computer input-output equipment computer network architectures DATA transmission systems GRAPH algorithms computer algorithms

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Design and control of a four-wheeled omnidirectional mobile robot with steerable omnidirectional wheels

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JOURNAL OF ROBOTIC SYSTEMS 2004年第4期21卷 193-208页

作者： Song, JB Byun, KS Korea Univ Dept Mech Engn Seoul 136701 South Korea

Omnidirectional mobile robots are capable of arbitrary motion in an arbitrary direction without changing the direction of wheels, because they can perform 3 degree-of-freedom (DOF) motion on a two-dimensional plane. In this research, a new class of omnidirectional mobile robot is proposed. Since it has synchronously steerable omnidirectional wheels, it is called an omnidirectional mobile robot with steerable omnidirectional wheels (OMR-SOW). It has 3 DOFs in motion and one DOF in steering. One steering DOF can function as a continuously variable transmission (CVT). CVT of the OMR-SOW increases the range of velocity ratio from the wheel velocities to robot velocity, which may improve performance of the mobile robot. The OMR-SOW with four omnidirectional wheels has been developed in this research. Kinematics and dynamics of this robot will be analyzed in detail. Various tests have been conducted to demonstrate the validity and feasibility of the proposed mechanism and control algorithm. (C) 2004 Wiley Periodicals, Inc.

关键词： Velocity Ratio Standing Orders Omnidirectional mobile robot DEPTH OF FIELD Robot Wheels computer algorithms

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Improving reproducibility and sensitivity in identifying human proteins by shotgun proteomics

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ANALYTICAL CHEMISTRY 2004年第13期76卷 3556-3568页

作者： Resing, KA Meyer-Arendt, K Mendoza, AM Aveline-Wolf, LD Jonscher, KR Pierce, KG Old, WM Cheung, HT Russell, S Wattawa, JL Goehle, GR Knight, RD Ahn, NG Univ Colorado Dept Chem & Biochem Boulder CO 80309 USA Univ Colorado Howard Hughes Med Inst Boulder CO 80309 USA

Identifying proteins in cell extracts by shotgun proteomics involves digesting the proteins, sequencing the resulting peptides by data-dependent mass spectrometry (MS/MS), and searching protein databases to identify the proteins from which the peptides are derived. Manual analysis and direct spectral comparison reveal that scores from two commonly used search programs (Sequest and Mascot) validate less than half of potentially identifiable MS/MS spectra (class positive) from shotgun analyses of the human erythroleukemia K562 cell line. Here we demonstrate increased sensitivity and accuracy using a focused search strategy along with a peptide sequence validation script that does not rely exclusively on XCorr or Mowse scores generated by Sequest or Mascot, but uses consensus between the search programs, along with chemical properties and scores describing the nature of the fragmentation spectrum (ion score and RSP). The approach yielded 4.2% false positive and 8% false negative frequencies in peptide assignments. The protein profile is then assembled from peptide assignments using a novel peptide-centric protein nomenclature that more accurately reports protein variants that contain identical peptide sequences. An Isoform Resolver algorithm ensures that the protein count is not inflated by variants in the protein database, eliminating similar to25% of redundant proteins. Analysis of soluble proteins from a human K562 cells identified 5130 unique proteins, with similar to100 false positive protein assignments.

关键词： PROTEINS PROTEOMICS AMINO acid sequence PEPTIDES MASS spectrometry SPECTRUM analysis computer algorithms

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