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71.
Using the phenomenon of magnetic induction a method for measuring the relative axial and radial displacements between reinforcing
steel and concrete has been developed. For this measuring system a Hall sensor is glued to the surface of the reinforcing
steel to receive the variable magnetic induction caused by a permanent magnet placed within the concrete. 相似文献
72.
Flow phenomena, local heat and mass transfer and pressure drop of corrugated passages in process equipment are examined. Based on a method for measuring local heat and mass transfer, developed in previous investigations, a procedure has been formulated for the determination of local heat and mass transfer in corrugated passages. Using the analogy between heat and mass transfer, this technique allows the determination of heat transfer distributions in any structures with high local resolution. The corresponding pressure drop is presented together with the local and integral heat and mass transfer of different structures. It is shown that differences in heat and mass transfer as well as in pressure drop are due to different flow phenomena which also characterize mixing behaviour. 相似文献
73.
The authors present and test a new method of teaching Bayesian reasoning, something about which previous teaching studies reported little success. Based on G. Gigerenzer and U. Hoffrage's (1995) ecological framework, the authors wrote a computerized tutorial program to train people to construct frequency representations (representation training) rather than to insert probabilities into Bayes's rule (rule training). Bayesian computations are simpler to perform with natural frequencies than with probabilities, and there are evolutionary masons for assuming that cognitive algorithms have been developed to deal with natural frequencies. In 2 studies, the authors compared representation training with rule training; the criteria were an immediate learning effect, transfer to new problems, and long-term temporal stability. Rule training was as good in transfer as representation training, but representation training had a higher immediate learning effect and greater temporal stability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
74.
This study investigated the effects of organic and colloidal fouling on the removal of a representative micropollutant sulphamethoxazole by two commercially available NF membranes. Alginate, bovine serum albumin and colloidal silica were selected as model foulants to simulate hydrophilic and hydrophobic organic fractions, and colloidal matter that are often found in treated effluent and surface water. Membrane fouling was related to the membrane and foulant characteristics and subsequently the separation behaviour of the micropollutant sulphamethoxazole under different solution pH. On the basis of these results, it was confirmed that membrane fouling is strongly dependent on both the foulant and membrane characteristics. The complex relationship among retention mechanisms, fouling mechanisms and the effects of fouling on retention was systematically delineated. Of the three model foulants selected for this study, colloidal fouling resulted in the most significant reduction in retention of sulphamethoxazole as well as inorganic salts, while flux decline as a result of colloidal fouling was quite moderate. Reduction in retention caused by fouling was attributed to a phenomenon known as cake-enhance concentration polarisation, which was a predominant mechanism of colloidal fouling. In addition, the reported results suggested that the effect of fouling on retention is also membrane pore size dependent. 相似文献
75.
Zusammenfassung. Es wird die Arbeitsweise der klinischen Ethik-Konsultation am Klinikum der Philipps-Universit?t Marburg anhand eines konkreten
Falles dargestellt. Grundlegend für diese Vorgehensweise ist die Theorie und Praxis eines Ethik-Konsildienstes, wie sie am
Medical Center der University of Virginia von J.C. Fletcher, F.G. Miller und J.J. Fins entwickelt wurde.
相似文献
76.
77.
The stability behaviour of hard material coatings made by CVD on different alloyed and carbon steel substrates depends on the properties of both substrate and coating. SEM in-situ investigations on the tension loaded surface of bended samples may be used to observe crack nucleation and growth in brittle hard material coatings such as TiC, TiCN on low alloyed and carbon steels. From the crack distance distributions some important parameters of mechanical stability such as the threshold value of fracture σth, the Weibull-parameter β and the ratio of the strength distribution function F and a characteristic length D may be estimated. The threshold value for fracture in the coatings σth decreases with increasing coating thickness for all steel-coating combinations. The threshold value also decreases if a heat treatment is made on the steel-coating system. This is due to the relaxation of the internal stress in the coating. The mean strength of the TiC-coatings decreases and the strength variance (measured by the Weibull-parameter β) increases with increasing coating thickness and therefore the mechanical stability of coatings decreases with growing thickness. The ratio of the strength distribution function F and the characteristic distance between defects D as a measure of crack density depends on the deformation behaviour of the steel as well as on the strength and the defect structure of the coating. 相似文献
78.
The determination of water application parameters for creating an optimal soil moisture profile represents a complex nonlinear optimization problem which renders traditional optimization into a cumbersome procedure. For this reason, an alternative methodology is proposed which combines a numerical subsurface flow model and artificial neural networks (ANN) for solving the problem in two, fully separate steps. The first step employs the flow model for calculating a large number of wetting profiles (output), obtained from a systematic variation of both water application and initial soil moisture (input). The resulting matrix of corresponding input/output values is used for training the ANN. The second step, the application of the fully trained ANN, then provides the irrigation parameters which range from a specified initial soil moisture to a desired crop-specific soil moisture profile. In order to avoid substantial disadvantages associated with the common feedforward backpropagation approach, a self-organizing topological feature map is implemented to perform this task. After a comprehensive sensitivity analysis, the new methodology is applied to the outcome of an irrigation experiment. The convincing results recommend the new methodology as a positive contribution towards an improved irrigation efficiency. 相似文献
79.
80.
Scale-down of chemical engineering pilot plant – what is attainable? The use of fully automated experimental laboratory-scale plantoffer interesting possibilities for assessment of the economic operation and technical feasibility of new or modified processes. An important condition for the success of this kind of experimental approach is the availability of miniaturized equipment, machines, and sensors. The goal of such experimental plant can be both the process engineering development of individual process steps and also integrated running to model complete processes. Moreover, questions of scale-up can be studied and typical quantities can be provided. The state of the art is reported with the aid of selected examples of equipment and mechanical components and measurement and control units. 相似文献