| 1. |
- Bengtsson, Lars, 1958-, et al.
(författare)
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REMAP massively parallel computer platform for neural computations
- 1997
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Ingår i: Proceedings of the Third International Conference on Microelectronics for Neural Networks (MicroNeuro’93). ; , s. 47-62
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Konferensbidrag (refereegranskat)abstract
- The REMAP project addresses questions related to the use of massively parallel, distributed computing in embedded systems. Of specific interest is the execution of artificial neural network algorithms on multiple, cooperating processor arrays. This paper concentrates on the recently finished, and currently used, processor array prototype, REMAP-β, of SIMD (Single Instruction stream, Multiple Data streams) type. The architecture and implementation of the computer is described, both its overall structure and its constituent parts. Following this comes a discussion of its use as an architecture laboratory, which stems from the fact that it is implemented using FPGA (Field Programmable Gate Array) circuits. As an architecture laboratory the prototype can be used to implement and evaluate, e.g., various Processing Element (PE) designs. A couple of examples of PE architectures, including one with floating-point support, are given. The mapping of important neural network algorithms on processor arrays of this kind is shown, and possible tuning of the architecture to meet specific processing demands is discussed. Performance figures are given as well as implications for future VLSI implementations of the array.
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| 2. |
- Jonsson, Magnus, 1969-, et al.
(författare)
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A fiber-optic interconnection concept for scaleable massively parallel computing
- 1995
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Ingår i: Proceedings of the Second International Conference on Massively Parallel Processing Using Optical Interconnections. - Piscataway, NJ. : IEEE. - 0818671017 ; , s. 313-320
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Konferensbidrag (refereegranskat)abstract
- One of the most important features of interconnection networks for massively parallel computer systems is scaleability. The fiber-optic network described in this paper uses both wavelength division multiplexing and a configurable ratio between optics and electronics to gain an architecture with good scaleability. The network connects distributed modules together to a huge parallel system where each node itself typically consists of parallel processing elements. The paper describes two different implementations of the star topology, one uses an electronic star and fiber optic connections, the other is purely optical with a passive optical star in the center. The medium access control of the communication concept is presented and some scaleability properties are discussed involving also a multiple-star topology.
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| 3. |
- Jonsson, Magnus, 1969-, et al.
(författare)
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Fiber-ribbon pipeline ring network for high-performance distributed computing systems
- 1997
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Ingår i: Proceedings of the Third International Symposium on Parallel Architectures, Algorithms, and Networks, 1997. (I-SPAN '97). - : IEEE. ; , s. 138-143
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Konferensbidrag (refereegranskat)abstract
- In this paper, we propose a high-bandwidth ring network built up with fiber-ribbon point-to-point links. The network has support for both packet switched and circuit switched traffic. Very high throughputs can be achieved in the network due to pipelining, i.e., several packets can be traveling through the network simultaneously but in different segments of the ring. The network can be built today using fiber-optic off-the-shelf components. The increasingly good price/performance ratio for fiber-ribbon links indicates a great success potential for the proposed kind of networks. We also present a massively parallel radar signal processing system with exceptionally high demands on the communication network. An aggregated throughput of tens of Gb/s is needed in this application, and this is achieved with the proposed network.
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| 4. |
- Jonsson, Magnus, 1969-
(författare)
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High performance fiber-optic interconnection networks for real-time computing systems
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Parallel and distributed computing systems become more and more powerful and hence place increasingly higher demands on the networks that interconnect their processors or processing nodes. Many of the applications running on such systems, especially embedded systems applications, have real-time requirements and, with increasing application demands, high-performance networks are the hearts of these systems. Fiber-optic networks are good candidates for use in such systems in the future. This thesis contributes to the relatively unexplored area of fiber-optic networks for parallel and distributed real-time computer systems and suggests and evaluates several fiber-optic networks and protocols. Two different technologies are used in the networks, WDM (Wavelength Division Multiplexing) and fiber-ribbon point-to-point links. WDM offers multiple channels, each with a capacity of several Gbit/s. A WDM star network in which protocols and services are efficiently integrated to support different kinds of real-time demands, especially hard ones, has been developed. The star-of-stars topology can be chosen to offer better network scalability. The WDM star architecture is attractive but its future success depends on components becoming more commercially mature. Fiber-ribbon links, offering instead an aggregated bandwidth of several Gbit/s, have already reached the market with a promising price/performance ratio. This has motivated the development and investigation of two new ring networks based on fiber-ribbon links. The networks take advantage of spatial bandwidth reuse, which can greatly enhance performance in applications with a significant amount of nearest downstream neighbor communication. One of the ring networks is control channel based and not only has support for real-time services like the WDM star network but also low level support for, e.g., group communication. The approach has been to develop network protocols with support for dynamic real-time services, out of time-deterministic static TDMA systems. The focus has been on functionality more than pure performance figures, mostly on real-time features but also on other types of functionality for parallel and distributed systems. Worst-case analyses, some simulations, and case studies are reported for the networks. The focus has been on embedded supercomputer applications, where each node itself can be a parallel computer, and it is shown that the networks are well suited for use in the radar signal processing systems studied. Other application examples in which these kinds of networks are valuable are distributed multimedia systems, satellite imaging and other image processing applications.
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| 5. |
- Jonsson, Magnus, 1969-, et al.
(författare)
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On inter-cluster communication in a time-deterministic WDM star network
- 1997
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Ingår i: Proc. 2nd Workshop on Optics and Computer Science (WOCS), Geneva, Switzerland, Apr. 1, 1997. ; , s. 10-
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Konferensbidrag (refereegranskat)abstract
- Future real-time applications requiring massively parallel computer systems also put high demands on the interconnection network. By connecting several WDM star clusters by a backbone star, forming a star-of-stars network, we get a modular high-bandwidth network. In this paper we show how to achieve time-deterministic packet switched communication in such networks, even for inter-cluster communication. An analysis of how the deterministic latency and node bandwidth vary with design parameters is presented. We also propose a general clock-synchronization scheme, improving the worst-case latency with up to 33 percentages.
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| 6. |
- Jonsson, Magnus, 1969-, et al.
(författare)
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Time-deterministic WDM star network for massively parallel computing in radar systems
- 1996
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Ingår i: Proceedings of the Third International Conference on Massively Parallel Processing Using Optical Interconnections. - Los Alamitos, California : IEEE Computer Society Press. - 0818675918 ; , s. 85-93
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Konferensbidrag (refereegranskat)abstract
- In massively parallel computer systems for embedded real-time applications there are normally very high bandwidth demands on the interconnection network. Other important properties are time-deterministic latency and services to guarantee that deadlines are met. In this paper we analyze how these properties vary with the design parameters for a passive optical star network, specifically when used in a massively parallel radar signal processing system. The aggregated bandwidth and computational power of the radar system are approximately 45 Gb/s and 100 GOPS, respectively. The analysis is focused on the medium access control protocol, called TD-TWDMA, for the time and wavelength multiplexed network. It is concluded that the proposed network is very well suited to this kind of signal-processing applications. We also present a new distributed slot-allocation algorithm with real-time properties.
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| 7. |
- Kruusmaa, Maarja, et al.
(författare)
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A low-risk approach to mobile robot path planning
- 1998
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Ingår i: Lecture Notes in Computer Science. - Heidelberg : Springer Berlin/Heidelberg. - 0302-9743 .- 1611-3349. ; 1416, s. 132-141
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a self-organizing approach for mobile robot path planning problems in dynamic environments by using case-based reasoning together with a more conventional method of grid-map based path planning. The map-based path planner is used to suggest new innovative solutions for a particular path planning problem. The case-base is used to store the paths and evaluate their traversability. While planning the route those paths are preferred which, according to former experience, are least risky. As the environment changes, the exploration as well as the evaluation of the paths will allow the system to self-organize by forming a set of low-risk paths that are safest to follow. The experiments in a simulated environment show that the robot is able to adapt in a dynamic environment and learns to use the least risky paths. © Springer-Verlag Berlin Heidelberg 1998.
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| 8. |
- Taveniku, Mikael, et al.
(författare)
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A multiple SIMD mesh architecture for multi-channel radar processing
- 1996
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Ingår i: Proceedings of: ICSPAT'96, international conference on signal processing applications & technology, Boston MA, USA, October 7-10. - : Miller Freeman. ; , s. 1421-1427
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Konferensbidrag (refereegranskat)abstract
- In modern and future radar applications there are high demands on the signal processing chain in terms of computational power and generality. At the same time, there are hard size and power consumption constraints. This paper reports on a project whose aim is to find a good scalable computer architecture that is flexible, programmable and as general-purpose as possible without too much performance loss.The proposed architecture consists of multiple SIMD computing modules, each based on a number of small mesh arrays. The modules are fully programmable and work globally as a MIMD machine and locally as SIMD machines. The data network is modular and provides both high bandwidth capacity and fast response. It has a fiber-optic stars topology, and employs time and wavelength division multiplexing, together with a medium access method specially developed for real-time systems.In this paper, we use a radar system with 64 processing channels to illustrate the algorithms and the usage of the processor modules. We show that it is possible to use a machine, consisting of small mesh processor arrays forming larger modules, with good efficiency. The building blocks show good balance between computational power and I/O bandwidth, and the SIMD approach seems good from algorithm-mapping point of view.
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| 9. |
- Taveniku, Mikael, et al.
(författare)
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The VEGA moderately parallel MIMD, moderately parallel SIMD, architecture for high performance array signal processing
- 1998
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Ingår i: Proceedings of the first merged International Parallel Processing Symposium & Symposium on Parallel and Distributed Processing. - Los Alamitos, Calif. : IEEE Computer Press. ; , s. 226-232
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Konferensbidrag (refereegranskat)abstract
- In array radar signal processing applications, the processing demands range from tens of GFLOPS to several TFLOPS. To address this, as well as the, size and power dissipation issues, a special purpose “array signal processing” architecture is proposed. We argue that a combined MIMD-SIMD system can give flexibility, scalability, and programmability as well as high computing density. The MIMD system level, where SIMD modules are interconnected by a fiber-optic real-time network, provides the high level flexibility while the SIMD module level provides the compute density. In this paper we evaluate different design alternatives and show how the VEGA architecture was derived. By examining the applications and the algorithms used, the SIMD mesh processor is found be sufficient. However, the smaller the meshes are the better is the flexibility and efficiency. Then, based on prototype VLSI implementations and on instruction statistics, we find that a relatively large pipelined processing element maximises the performance per area. It is thereby concluded that the small SIMD mesh processor array with powerful processing elements is the best choice. These observations are further exploited in the design of the single-chip SIMD processor array to be included in the MIMD-style overall system. The system scales from 6.4 GFLOPS to several TFLOPS peak performance.
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| 10. |
- Wickström, Nicholas, et al.
(författare)
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Estimating pressure peak position and air-fuel ratio using the ionization current and artificial neural networks
- 1997
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Ingår i: IEEE Conference on Intelligent Transportation Systems. - Piscataway, N.J. : IEEE. - 0780342690 ; , s. 927-977
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We propose two artificial neural network models which use the ionization current for estimation of the position of the pressure peak and the air-fuel ratio. The pressure peak position model produces estimates on a cycle-by-cycle basis for each of the cylinders. These estimates are twice as good as estimates obtained from a linear model. The air-fuel ratio model uses the universal exhaust gas oxygen sensor as reference; it produces estimates that are ten times better than estimates obtained fi om a linear model.
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