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101.
New accurate two-noded shear-flexible curved beam elements 总被引:2,自引:0,他引:2
There are two purposes of this work. One is to present two accurate two-noded finite elements which are derived from the
potential energy principle and the Hellinger–Reissner functional principle respectively. The second is to show the successful
application of the internal displacement parameters in developing a high-order related displacement-rotation interpolation
field. Because the derived interpolation field is capable of accurately modeling deformation modes in extreme thin curved
beams and nearly straight beams, both shear locking and membrane shocking are avoided. Several standard numerical tests display
superior behaviors of the present elements.
Received: 5 February 2002 / Accepted: 16 September 2002 相似文献
102.
103.
Christine Di Massimo Paul A. Lant Aidan Saunders Gary A. Montague Ming T. Tham A. Julian Morris 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,53(3):265-277
The last decade has seen the development of a number of approaches for estimating those variables which are difficult to measure on-line in industrial process situations. Whilst a range of techniques is available, a common element is the use of process knowledge in the form of a system model. In the case of bioprocess systems, although a large range of models has been presented in the literature, their use in estimation schemes on an industrial scale has been limited. A number of reasons can be identified for their low level of utilisation. Of particular significance is the uncertainty which exists in quantifying system performance and the process-model mismatch which inevitably results. The level of ‘pre-defined model’ uncertainty, together with the knowledge gained during the course of the fermentation, serves to dictate estimator structure. The paper considers a range of estimation strategies and contrasts, through industrial applications, their performance characteristics and utility. 相似文献
104.
The aim of the conceptual step in database design is to describe data involving in the application in a formal and abstract way, without any concern to the specific model and language chosen for the implementation. In statistical applications, data are described at different levels of aggregation, from elementary facts of the reality to complex aggregations such as classifications, time series, indexes. The paper describes a methodology for conceptual design of statistical databases that provides the designer suitable strategies for defining such different levels of aggregation starting from user requirements, and checking the completeness, coherence and minimality of the conceptual schema at the different levels. The methodology makes use of two data models for the representation of data: for elementary data the Entity-Relationship model, widely used in database applications, and for summary data a new model is proposed, designed to be an effective trade-off between expressive power and simplicity of use. 相似文献
105.
106.
分布系统中多米诺效应的分析与消除 总被引:3,自引:0,他引:3
分布系统中发生故障后,错误信息在进程间的传播,以及由此引起的系统恢复过程中的多米诺效应是分布系统容错恢复技术所面临的最重要与最困难的问题.目前各种研究工作偏重于具体的系统动态恢复技术.本文的研究重点在于首次揭示多米诺效应本身固有的数量特征及其与分布系统技术参数间的联系,给出多米诺效应动态消除技术,引入系统额外开销的下限,并针对动态技术的缺点,探讨多米诺效应的静态消除技术,为解决困难开辟新途径. 相似文献
107.
Ginevra Lombardi-Boccia Giuseppe Di Lullo Emilia Carnovale 《Journal of the science of food and agriculture》1991,55(4):599-605
In-vitro iron dialysability from five Italian legumes (mottled bean, white bean, faba bean, chickpea, lentil) and the influence of phytate and extrusion cooking on it were evaluated. Iron dialysability was 2·3 and 2·4% in mottled and white bean respectively, 1·2% infaba bean, 2·7% in chickpea and 1·1% in lentil. After extrusion cooking the flours showed a marked iron contamination and a decrease in iron dialysability, but these changes were significant only for mottled bean. Enzymic phytate removal induced an increase in iron dialysability > 100% in all the raw legumes except mottled bean which showed an increase of only 57%. This finding indicates that, although phytate consistently modifies iron dialysability, it is difficult to identify a quantitative relationship between phytate content and iron dialysability. 相似文献
108.
109.
1. Introduction Seismic physical modeling technology is an important method for the research on seismic exploration theory and methods. In seismic physical experiments, the earth, mantle or field site are scaled down to physical models according to the similarity principle, and then the seismic field and its variation are observed in the laboratory for the research work on the theories and methods of the earth structure, earthquake forecasting, energy and mineral resource exploration, and engi… 相似文献
110.
狄宁 《重庆科技学院学报(社会科学版)》2008,(11)
后晋天福三年(938年),"儿皇帝"石敬瑭"履约"向契丹割献燕云十六州.从此,中原王朝丧失了抵御北方游牧民族入侵的天然屏障,北方门户大开.宋代,燕云地区的争夺几乎贯穿了十至十二世纪北宋与辽金战争的整个过程.事实上,后人所指的"燕云十六州"与石敬瑭割辽的十六州在名称、时间和地域上有很大的差别;燕云地区内的险峻的山脉、横贯的河流与长城、五关一起构成了其巨大的军事价值;富庶的经济,众多的人口又构成了该地区巨大的经济价值;从历史上看,燕云十六州的归属于中原王朝和北方游牧民族政权双方而言,战略意义重大. 相似文献