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81.
基于支持向量机的多类分类研究 总被引:1,自引:0,他引:1
现今流行的分类方法的重要基础是传统的统计学,前提是要有足够的样本,当样本数目有限时容易出现过学习的问题,导致分类效果不理想。引入支持向量机方法,它基于统计学习理论,采用了结构风险最小化原则代替经验风险最小化原则,较好的解决了小样本学习的问题;又由于采用了核函数思想,把非线性空间的问题转换到线性空间,降低了算法的复杂度。对其相关内容包括优化算法及多类分类问题的解决进行了研究,最后用一个实例说明了该方法的可行性和有效性。 相似文献
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Starting from a microscopic Hamiltonian defined on a semi-infinite cubic lattice, and employing a mean-field approximation, the surface parameters relevant for wetting in confined ternary mixtures are derived. These are found in terms of the microscopic coupling constants, and yield a physical interpretation of their origins. In comparison with the standard expression for the surface free-energy density, several new terms arising from the derivation are identified. The influence of the surface parameters on a predicted unbinding transition in a mixture of oil, water, and amphiphile demonstrate that existing results are robust to the addition of the extra surface terms. 相似文献
84.
A. Kaveh V. Kalatjari 《International journal for numerical methods in engineering》2003,58(5):771-791
In this article size/topology optimization of trusses is performed using a genetic algorithm (GA), the force method and some concepts of graph theory. One of the main difficulties with optimization with a GA is that the parameters involved are not completely known and the number of operations needed is often quite high. Application of some concepts of the force method, together with theory of graphs, make the generation of a suitable initial population well‐matched with critical paths for the transformation of internal forces feasible. In the process of optimization generated topologically unstable trusses are identified without any matrix manipulation and highly penalized. Identifying a suitable range for the cross‐section of each member for the ground structure in the list of profiles, the length of the substrings representing the cross‐sectional design variables are reduced. Using a contraction algorithm, the length of the strings is further reduced and a GA is performed in a smaller domain of design space. The above process is accompanied by efficient methods for selection, and by using a suitable penalty function in order to reduce the number of numerical operations and to increase the speed of the optimization toward a global optimum. The efficiency of the present method is illustrated using some examples, and compared to those of previous studies. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
85.
Requirements engineering in health care: the example of chemotherapy planning in paediatric oncology
Health care is characterized by highly complex processes of patient care that require unusual amount of communication between different health care professionals of different institutions. Sub-optimal processes can significantly impact on the patient’s health, increase the consumption of services and resources and in severe cases can lead to the patient death. For these reasons, requirements engineering for the development of information technology in health care is a complex process as well: without constant and rigorous evaluation, the impact of new systems on the quality of care is unknown and it is possible that badly designed systems significantly harm patients. To overcome these limitations, we present and discuss an approach to requirements engineering that we applied for the development of applications for chemotherapy planning in paediatric oncology. Chemotherapy planning in paediatric oncology is complex and time-consuming and errors must be avoided by all means. In the multi-hospital/multi-trial-centre environment of paediatric oncology, it is especially difficult and time-consuming to analyse requirements. Our approach combines a grounded theory approach with evolutionary prototyping based on the constant development and refinement of a generic domain model, in this case a domain model for chemotherapy planning in paediatric oncology. The prototypes were introduced in medical centres and final results show that the developed generic domain model is adequate. 相似文献
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西部地区深井井身结构设计技术探讨 总被引:3,自引:2,他引:1
科学合理地确定井身结构及钻井液密度是深井超深井钻井的关键环节之一,其基础是准确建立地层孔隙压力、地应力、破裂压力、坍塌压力的钻前预测剖面。分析了西部地区目前深井井身结构的缺点和进行井身结构应考虑的问题,介绍了深探井井身结构的设计方法,并针对西部复杂地区的地层特点,建议采用3种增加技术套管的井身结构方案。塔河油田钻井实践表明,采用这3种井身结构方案后,深井机械钻速得到提高,钻井周期缩短,而且降低了钻井成本。 相似文献
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通过建立变形介质中考虑启动压力梯度的一维两相宾汉稠油驱替的数学模型,并进行了数值求解,分析了地层变形以及启动压力梯度对水驱稠油的影响,分析表明:介质变形对含水饱和度的分布没有影响,而对地层压力的影响是非常显著的,随着变形介质弹性的增加,地层压力越来越低,并且越靠近注入端,地层压力下降越快;原油的启动压力梯度同时影响含水饱和度和地层压力的分布,在其它条件一定时,启动压力梯度的存在,造成地层压力的增加和平均含水饱和度的降低。在油田开发实际中,应考虑地层变形和启动压力梯度的影响,以提高原油采收率。 相似文献