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An ultra-high pressure jet of water and air with simultaneous cement grouting is revolutionishing the practice of ground consolidation and foundation reinforcement. Swedish research has been studying this development, briefly explained here. The note report is based on a summary note issued by the Swedish Council for Building Research. 相似文献
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Olav Benestad Lars Brinck Lennart Emborg Bjarne Juul-Kristensen Alexander Kristiansen Niels I. Meyer Kysti Pulliaine Eivind Selvig Anssi Vaittinen 《Energy Policy》1993,21(12):1225-1236
The concept of a sustainable energy sector has received wide attention since the publication of the Brundtland Report in 1987. This paper analyses the possibilities of establishing by 2010 and 2030 an energy system in the Nordic countries which prevents the critical loads of NOx and SO2 respectively on the most vulnerable Nordic ecological systems being exceeded. In addition, the present concentration of CO2 in the atmosphere should not be significantly exceeded within a time horizon to around 2050. Different scenarios have been investigated in order to analyse the scope for attaining such a sustainable energy development within the limits of existing technologies and known potentials of renewable energy sources. Data on the technologies are available in a special catalogue. 相似文献
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A measurement of the NBS electrical watt in SI units 总被引:2,自引:0,他引:2
Olsen P.T. Elmquist R.E. Phillips W.D. Williams E.R. Jones G.R. Jr. Bower V.E. 《IEEE transactions on instrumentation and measurement》1989,38(2):238-244
The National Bureau of Standards (NBS) electric watt in SI units to be: W NBS/W =K W =1-(16.69±1.33) p.p.m. The uncertainty of 1.33 p.p.m. has the significance of a standard deviation and includes the best estimate of random and known or suspected systematic uncertainties. The mean time of the measurement is May 15, 1988. Combined with the measurement of the NBS ohm in SI units: ΩNBS/Ω=K Ω =1-(1.593±0.022) p.p.m., this leads to a Josephson frequency/voltage quotient of E J=E0[1+(7.94±0.67) p.p.m.] where E 0=483, 594 GHz/V 相似文献
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An investigation was made on whether the optimal number of tubes in a dry-expansion evaporator, for a given area or a given cost, will change when R22 is replaced with the non-azeotropic mixture R407C. A comprehensive computer program was used to simulate the tube-and-shell evaporator, under several sets of conditions. The simulations show that there are only small differences between R22 and R407C in the optimal number of tubes. However, the results indicate that one can allow a somewhat higher pressure drop for R407C, and that the number of tubes for a given area therefore can be smaller when R407C is used. For both fluids, the evaporator performance is more sensitive to the optimization for a given cost than for a given area. 相似文献
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Nils Kjellman Krister Kristiansson Lennart Malmqvist 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》1985,235(1):193-197
A method has been worked out to identify lithium and boron in mineral samples by means of a solid state nuclear track detector technique. The samples have been irradiated with thermal neutrons which react with 10B and 6Li and give α-particles of different energies. The ranges of these α-particles in air are measured with the SSNTD-technique and found to be sufficiently different to make identification possible. A number of tests are made and the possibility for determining the distribution and the abundance of lithium and boron in a specific mineral in a rock sample is discussed. 相似文献
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Detailed calculations are carried out for condensation of a binary zeotropic mixture outside a tube bank to investigate combined effects of mass transfer resistances in the liquid and vapour phases. The question is how a change in mass transfer resistance in the vapour phase can influence the heat flux. The surprising result is that a decrease in resistance in the vapour phase by reducing the tube pitch, and thus increasing the vapour velocity, reduces the heat flux between 20% and 50% for the conditions studied. This is due to a combination of mass transfer resistance, depletion of the heavy volatile component, and a reduction of the phase interface temperature. 相似文献