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- Borgström, Karin Margaretha, 1956-
(författare)
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Determination of the thermal conductivity of the insulation in district heating mains : Field measurements
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the development of a measurement method for determination in the field of the thermal conductivity of the insulation in buried district heating mains. The thermal conductivity of the insulation is calculated from the measured value of the radial heat flow through the heating main, the measured temperature difference across the insulation, and the dimensions of the heating main. The heat flow has been measured with a heat flux sensor which was fitted to the surface of the casing. The temperature has been measured with copper/constantan thermocouples. It is a necessary condition for the method used in the project for determination of the thermal conductivity of the heating main insulation that the heating main is uncovered and is not in contact with the surrounding soil over a distance of about 1.5 m and that the measurements are made directly on the heating main. In this way, no account need be taken of the material surrounding the heating main, nor of the effect of this material on the measurements. No interference is needed with the heating main which would affect the distribution of the district heating water, and the heating main can remain in operation during measurements. Shielding insulation consisting of preformed insulation sections which were placed over the casing of the heating main and covered the heat flux sensor and some of the casing. The function of this insulation was to shield the heat flux sensor from external thermal disturbances. In the field measurements, a copper guard plate of 0.5 mm thickness, the temperature of which could be adjusted, was also placed over the shielding insulation in order to maintain the temperature on the heat flux sensor as constant as possible. When temperature and heat flow are measured, the instruments used will be affected by conditions which prevail at the time of measurement. It is therefore very important to analyse the sources of error which may arise in the measuring situation at hand. The effect of these factors on the measured values has been studied by ' laboratory measurements ' theoretical calculations ' field measurements On the basis of the resulting values of heat flows and temperatures obtained in field measurements on plastic heating mains which were operating under normal conditions, the thermal conductivity of the insulation of the main has been estimated. The method has been tested on plastic heating mains with directly foamed insulation, since this is the most common type of heating main both in the existing district heating network and in new construction. The measuring method can also be used on other circular heating mains.
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| 2. |
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| 3. |
- Akujor, Chidi E., et al.
(författare)
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Combined-Array Imaging of Extra-Galactic Radio Sources
- 1994
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Ingår i: Astronomy with Millimeter and Submillimeter Wave Interferometry. - San Francisco : Astronomical Society of the Pacific. - 0937707783 ; , s. 123-124
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Konferensbidrag (refereegranskat)
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| 4. |
- Bengtsson, Lars, 1958-, et al.
(författare)
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A high-performance embedded massively parallel processing system
- 1994
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Ingår i: Proceedings of the First International Conference on Massively Parallel Computing Systems (MPCS) The Challenges of General-Purpose and Special-Purpose Computing. - Piscataway, N.J. : IEEE. - 0818663227 - 9780818663222 ; , s. 201-206
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Konferensbidrag (refereegranskat)abstract
- A need to apply the massively parallel computing paradigm in embedded real-time systems is foreseen. Such applications put new demands on massively parallel systems, different from those of general purpose computing. For example, time determinism is more important than maximal throughput, physical distribution is often required, size, power, and I/O are important, and interactive development tools are needed. The paper describes an architecture for high-performance, embedded, massively parallel processing, featuring a large number of nodes physically distributed over a large area. A typical node has thousands of processing elements (PEs) organized in SIMD mode and is the size of the palm of a hand, Intermodule communication over a scalable optical network is described. A combination of wavelength division multiplexing (WDM) and time division multiplexing (TDM) is used. © 1994 IEEE.
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| 5. |
- Bengtsson, Lars, 1958-, et al.
(författare)
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Brains for Autonomous Robots : Hardware and Surgery Tools
- 1994
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Ingår i: Proceedings of PerAc '94. From Perception to Action. - Los Alamitos : IEEE. - 0818664827 - 9780818664823 ; , s. 436-439
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Konferensbidrag (refereegranskat)abstract
- This paper presents a hardware architecture and a software tool needed for future autonomous robots. Specific attention is given to the execution of artificial neural networks and to the need for a good inspection and visualization tool when developing this kind of systems. Achievable performance using state-of-the-art technology is estimated and module miniaturization issues are discussed. © 1994 IEEE.
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| 6. |
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| 7. |
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| 8. |
- Bååth, L.B. 1948-
(författare)
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AGN Variability and VLBI
- 1994
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Ingår i: Multi-Wavelength Continuum Emission of Agn. - Dordrecht : Kluwer Academic Publishers. - 0792327446 - 0792327454 ; , s. 181-186
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Bokkapitel (refereegranskat)abstract
- This contribution discusses the connection between variability in radio and optical with structural variations observed with VLBI. Structural changes do not have to start in the core, and intensity variations may be caused by components in the jet outside the core. The scenario is probably more complicated than present day theories assume.
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| 9. |
- Chu, H.S., et al.
(författare)
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AO 0235+164 - A "Heretic" BL Lac
- 1994
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Ingår i: VLBI TECHNOLOGY. - Tokyo : Terra Scientific Publishing Company. ; , s. 146-155
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Bokkapitel (refereegranskat)
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| 10. |
- Hertz, Erik, 1956-
(författare)
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A Device for Conversion of a Binary Floating-Point Number into a Binary 2-Logarithm or the Opposite
- 1994
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Patent (populärvet., debatt m.m.)abstract
- The present invention concerns a device for conversion of a binary floating-point number into a binary fix-point 2-logarithm number or the opposite. This is done in the case of conversion of a binary floating-point number by making the invention include an input register where the floating-point number is stored, an output register for the calculated logarithm, a device that transfers the exponent of the floating-point number from the input register to the output register, where it directly forms the characteristic of the logarithm, a device that transfers the fractional part of the mantissa of the floating-point number from the input register to an adder and also to one or more part circuits that form additional parts, a device that transfers the additional parts to the adder, said adder that adds the fractional part of the mantissa of the floating-point number and said additional parts and a device that transfers the sum from the adder to the output register where it forms the fractional part of 2-logarithm. The conversion from logarithm is carried out in a similar manner and with the same components.
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