| 1. |
- Tinnsten, Mats, et al.
(författare)
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Optimization of acoustic response
- 1999
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Ingår i: Structural Optimization. - 0934-4373. ; 18:1, s. 36-47
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Tidskriftsartikel (refereegranskat)abstract
- The expression 'acoustic optimization' can be applied to numerous different disciplines within the field of acoustics. From seismic waves, sound in the atmosphere through bioacoustic, psychoacoustics, and room and theater acoustics over shock and vibration in mechanical structures. This paper deals with the latter. Sound generated by vibrating structures is often called noise which is to be minimized. However, not all vibrating structures produce noise, for example the violin is also a vibrating structure that in most people's opinion produces sound called music. In the case of the violin, great effort is made not to minimize but to optimize the sound, i.e. to get the 'right' sound out of the structure. Acoustic optimization within this discipline involves automatic changes of structural design variables to obtain minimum or specified sound in specified regions inside or outside the structure. Examples of problem formulations and some theoretical considerations in the field of acoustic optimization in connection with vibrating mechanical structures will be pointed out. Four simple test cases are included as numerical examples of the method proposed.
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| 2. |
- Jonsson, Erland, 1946, et al.
(författare)
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An Attempt to Quantitative Modelling of Behavioural Security
- 1995
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Ingår i: Proceedings of the 11th International Information Security Conference - IFIP/SEC 1995. ; addendum, s. 44-57
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Tidskriftsartikel (refereegranskat)abstract
- This paper suggests a quantitative approach to security, and specifically to a security-concept, which is regarded as an attribute of dependability together with reliability, availability and safety. We note that security is a more complex attribute of dependability than are the other three, and that it can therefore be split into preventive and behavioural aspects. We show that, in addition to availability, confidentiality could be used to denote a new type of behavioural aspect of dependability. Integrity is interpreted in terms of fault prevention, and is not directly related to system behaviour. A practical measure for behavioural dependability attributes including confidentiality is defined. Due to the dependability viewpoint of security that we take, a measure could be derived using traditional reliability methods, such as Markov modelling. The measure is meant for practical trade-offs within a class of computer systems. The measure quantifies system performance on user-specified service levels, which may be operational or failed. Certain levels may be related to confidentiality degradations or confidentiality failures. A simple Reference Monitor example is given to illustrate the use of the measure. The calculation method is then extended to handle situations with non–exponential failure rates, which is the normal case in security applications, by means of using phase–type modelling. This is illustrated by introducing malicious software, such as a Trojan Horse into the Reference Monitor.
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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-, 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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| 5. |
- Karlsson, Lennart, et al.
(författare)
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Modeling of residual stresses and distortion development
- 1997
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Ingår i: Mathematical modelling of weld phenomena 3. - London : Institute of Materials. - 186125010X ; , s. 571-589
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Four examples are used to illustrate the current ability to calculate residual stress and distortion in situations of varying complexity. The methodology used is capable of allowing for interactions between thermal, mechanical, and transformation processes. Experimental values for a 2.25Cr-1Mo ferritic stainless steel were used in the simulation. It seems possible to simulate most welding situations given sufficient computer resources
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| 6. |
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| 7. |
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| 8. |
- Oldenburg, Mats, et al.
(författare)
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Experiments with one-sided spray-cooling of steel plates for evaluation of thermo-mechanical material models
- 1996
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Ingår i: Quenching and the control of distortion. - Materials Park, Ohio : ASM International. - 0871705842 ; , s. 267-273
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Konferensbidrag (refereegranskat)abstract
- The quenching process of thin plates is studied. In many industrial applications of quenching, there is a need for simple tests for evaluation of analysis methods and material models for simulations. The presented study is part of a program for the simulation of the combined pressing and quenching process of thin-walled structures. This type of manufacturing process is used in, e.g., the production of side-impact protection beams for cars. By the use of an experiment with one-sided spray-cooling of a thin strip, large deformations can be studied and followed in time. The prediction of the deformation of the strip can be regarded as a one-dimensional problem where the curvature of the strip is sought. The thermo-mechanical behavior of the material can be evaluated throughout the time-history of the tests. In order to match the deformation of the plate, the material model must predict the temperature distribution through the thickness of the plate in each point in time, the phase transformations taking place in each layer of the thin plate and the stress and strain components in each layer. Experiments have been performed with a material (Inconel 600) without phase transformations in the actual temperature and time scale and with a material with only martensitic transformations. Analyses with a thermo-elastic-plastic material model with transformation plasticity included have been performed
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| 9. |
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| 10. |
- 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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