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71.
72.
Gas induction in agitated vessels with turbine impellers can be modelled accurately by means of radial basis function neural nets. The results obtained with the radial basis neural net were significantly better than those obtained by multivariate regression models or standard back propagation neural nets. Moreover, by using the radial basis function neural net model, it was possible to conduct a sensitivity analysis of the variables affecting aeration. Increased medium density showed a strong adverse effect, while variation of the viscosity can cause an increase or a decrease in the rate of aeration, depending on the prevailing process conditions. 相似文献
73.
A new method is outlined which aims to predict high-cycle fatigue behavior of components which fail from stress-concentrators. This involves examination of the stress field in the vicinity of the stress-concentrator, and comparison with stress fields for cracks at known stress intensities. Methods which are currently used for simple notch geometries can thus be generalised, making the approach applicable to stress concentrators of any geometry. The method of prediction is shown to be stable, providing a solution of good accuracy when compared to analytical methods for standard specimen geometries. Favourable comparisons with experimental data have been achieved both for standard notches and for a corner geometry which represents a typical component case. 相似文献
74.
Possibilities and problems with the use of models as a communication tool in water resource management 总被引:2,自引:1,他引:1
Politicians and policy-makers, as well as modellers, often nurses an expectation that model derived results is an objective
source of information that can be used to support decisions. However, several prerequisites have to be dealt with in order
to ensure that models can be used as legitimate and efficient tools in water resource management. Based on empirical material
from recent studies on the use of models in stakeholder dialogues, mainly focusing on catchment nutrient transport, two central
problems are identified: (a) Models are laden with choices and thus depend on assumptions and priorities of modellers. (b)
There are several factors that influence ability and willingness of stakeholders (as information recovers) to criticize or
accept results of the modelling exercise. Recognized factors likely to influence stakeholders' acceptance of model derived
results include issues at stake, stakeholders' ability to criticize model derived information, and their trust in the institutions
that have developed or applied the used models. Identified prerequisites for successful use of models in integrated water
resource management include: consideration of user relevance, awareness of and preparedness to handle constraints linked to
communication of model-based results, transparency of used models and data and of involved uncertainties, mutual respect between
experts and stakeholders and between involved stakeholder groups, a robust institutional network, and sufficient time for
dialogues. Development and use of strategies for participatory modelling, based on a continuous dialogue between experts and
stakeholders is recommended as a way to facilitate that the prerequisites for a successful use of models in water resource
management are fulfilled. 相似文献
75.
C.W.Kenneth Keng 《Energy Economics》1985,7(4):241-258
Because of the huge volume of capital required to construct a modern electric power generating station, investment decisions have to be made with as complete an understanding of the consequences of the decision as possible. This understanding must be provided by the evaluation of future situations. A key consideration in an evaluation is the financial component. This paper attempts to use an econometric method to forecast the construction costs escalation of a standard Canadian nuclear generating station (NGS). A brief review of the history of Canadian nuclear electric power is provided. The major components of the construction costs of a Canadian NGS are studied and summarized. A database is built and indexes are prepared. Based on these indexes, an econometric forecasting model is constructed using an apparently new econometric methodology of forecasting modelling. Forecasts for a period of 40 years are generated and applications (such as alternative scenario forecasts and range forecasts) to uncertainty assessment and/or decision-making are demonstrated. The indexes, the model, and the forecasts and their applications, to the best of the author's knowledge, are the first for Canadian NGS constructions. 相似文献
76.
地方时与区时在电离层研究中的差异 总被引:2,自引:0,他引:2
本文指出混淆地时与区时两个时间概念在电离层研究中带来的差异的严重性,建议使用地方与区时这两个名词,而抛弃“本地时”和“当地时”等容易引起混淆的名词。 相似文献
77.
Hong ZHU 《Frontiers of Computer Science in China》2012,6(1):40-56
Meta-modelling plays an important role in model driven software development.In this paper,a graphic extension of BNF (GEBNF) is proposed to define the abstract syntax of graphic modelling languages.Fro... 相似文献
78.
79.
80.
The performance of a venturi scrubber in the removal of tar from gas in updraft gasification has been studied. The gasifier has been operated with a husk feed rate of 1.6 × 10?4 kg/s. The venturi scrubber has been operated at a superficial gas velocity of 56.4 m/s at the throat. A wide variety of scrubbing liquids having surface tensions ranging from 0.026 to 0.072 N/m have been used. The Qg/Ql, has been varied in the range of 1000–8000. The tar separation efficiency η has been found to vary from 51 to 98.5%. A mathematical model, assuming steady-state operation, has been developed considering very high pseudosolubility of tar in the scrubbing liquids. The predicted values of η have been compared with experimental results. The model satisfactorily explains the tar removal efficiency of the venturi for Qg/Ql values ranging from 4000 to 8000 for all scrubbing liquids. The following correlation has been developed for predicting venturi scrubber efficiency: . 相似文献