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91.
奇摄动三阶非线性边值问题 总被引:1,自引:1,他引:0
利用微分不等式技巧和Volterra型积分算子,研究了三阶非线性奇摄动边值问题εx^(3)=f(t,x,x′,w(ε)x^(3),ε),g(x′(0),x″(0)=0,x(1)=A,x′(1)=B的存在性及渐近估计。 相似文献
92.
93.
PMV (Predicted Mean Vote) is a widely used index for evaluating the thermal environment. However, few studies have been conducted to take physiological values directly as evaluating indices. This paper assumes a linear relation between body temperature and both sweating rate and heat produced by shivering, and introduces the linear relation into the human heat balance equation to revise the classic PMV. And the assumption of linear relation is subsequently proved. The revised PMV possesses the same characteristic of dependent heat load as that of the classic one, and moreover it is convenient to be calculated. 相似文献
94.
A practical assessment of stated preferences methods 总被引:1,自引:0,他引:1
Stated preferences data in the form of rankings, ratings and choices were collected in Santiago and discrete choice models estimated with them. The models were compared in terms of accuracy v/s the cost of obtaining the information and models. All methods produced reasonable but different models and fairly close subjective values of time. In terms of production costs the ranking method was a clear looser although the experimental design was slightly biased against it. Finally, the use of computerised interviews is highly recommended particularly for dealing with low income people. 相似文献
95.
建立整数型轨道状态最优综合维修计划模型 总被引:3,自引:0,他引:3
为实现高效的轨道不平顺养护维修,建立最优养护维修计划模型和采用大型养路机械进行作业是十分重要的。本文以养护维修时间为决策变量,以年度轨道不平顺平均值最小为目标函数,在考虑了一系列约束函数的情况下,建立了整数型轨道状态最优综合维修计划模型。该模型能有效利用现场的养护资源,从安全和舒适的角度出发来制定养护计划,该模型的建立从理论上解决了轨道不平顺状态计算机辅助决策系统的关键问题。 相似文献
96.
Kuniaki Shoji Rajesh Ramachandran Yuzo Kurobe Yasuhisa Hashizume 《Journal of Marine Science and Technology》2002,7(2):86-90
As a result of frequent marine disasters leading to the loss of human life and pollution of vast areas of the ocean, ship
manoeuvrability has become a very important characteristic of ship design. Among several recent experimental techniques to
determine ship manoeuvrability, the most popular is captive model testing using a planar motion mechanism (PMM). This article
describes some tests, analyses, and results of PMM tests in a circulating water channel (CWC) using a model of a training
ship. The hydrodynamic forces and moments acting on a model of the training ship Shioji Maru in pure yawing motion were measured, and hydrodynamic derivatives were obtained using two different methods of analysis:
singular value decomposition (a least-squares fit method) and Fourier analysis. Derivatives obtained from the tests were used
to simulate the turning trajectory of the actual ship, and these were compared with the results of sea trials. The results
indicate that both methods of analysis yield fairly similar derivatives. The simulation results were also found to be a close
match with the trial results.
Received: February 7, 2002 / Accepted: May 14, 2002
Address correspondence to: K. Shoji (shoji@ipc.tosho-u.ac.jp) 相似文献
97.
本市以天津城市主干道卫津路拓宽改造工程为例,论述城市道路经济效益计算方法。按全天高峰小时、非高峰小时,分别计算机动车和非机动车的运营成本、时间价值及事故费用,采用有、无项目对比法.进行经济效益计算。经济效益中以车辆行程时间延误与路口时间延误的节约作为主要效益。 相似文献
98.
99.
Performance estimation model of a torque converter part I: Correlation between the internal flow field and energy loss coefficient 总被引:3,自引:0,他引:3
B. S. Kim S. B. Ha W. S. Lim S. W. Cha 《International Journal of Automotive Technology》2008,9(2):141-148
The objective of this paper is to improve the performance estimation model of the internal flow field of a torque converter.
Compared with performance experiment results, the converter based on the one-dimensional model does not satisfy the performance
requirements demanded in practice. Therefore, we need to develop more predictable and reliable performance estimation models.
In order to obtain shape information on three-dimensional blade geometry, a process of reverse engineering conducts a torque
converter assembly, impeller, turbine and stator. In addition, a CFD simulation including mesh generation and post-processing
was carried out to extract equivalent parameters from the internal flow field. The internal flow field can be explained by
analyze the correlation between a performance estimation model and CFD analysis. The equivalent performance model adopts the
variation of energy loss coefficients for a given operating condition according to the application of a changing energy loss
coefficient by the least mean squares method. The estimated equivalent model improves the agreement in performance between
experiments and the theoretical model. This model can reduce the error to within about 3 percent. Furthermore, this procedure
for predicted performance achieves eminence in the estimation of the capacity factor. 相似文献
100.
谢兰璋 《武汉船舶职业技术学院学报》2008,7(4):76-79
从企业现代竞争理论三个阶段的演变看,正是由于主流企业战略管理理论的不足才促使了企业核心竞争力理论的迅速兴起,核心竞争力的战略选择成为企业战略制定的关键问题。企业可以从经营业务战略、目标行业战略、市场竞争战略与资源组合战略四方面进行核心竞争力战略定位,确立以客户价值为中心的核心竞争力战略模式。 相似文献