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71.
72.
介绍了基于供应链管理的现代物流信息系统的基本特点 ;结合国有矿山企业当前的物资管理工作实际 ,提出了建立面向供应链的企业物资管理信息系统的基本思路和在建立过程中需要关注和解决的几个重要问题 相似文献
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74.
Scott L. Huang Matthew T. Bray Satoshi Akagawa Masami Fukuda 《Canadian Metallurgical Quarterly》2004,18(1):2-34
A large scale 105-m-long, 0.9-m-diam chilled pipeline experiment was conducted to assess the response of a production pipeline that transits between unfrozen (seasonally frozen) and permafrost soils in discontinuous permafrost regions. Thermal and heave characteristics of the experiment for a three-year monitoring period are reported. In response to the chilled pipeline, the progressive cooling patterns within the permafrost and unfrozen soils were different, resulting in the development of a thermal boundary at the transition zone between the two thermally different soils. The absolute maximum movement of pipeline was 0.197 m near the thermal boundary, resulting in a differential heave of 0.148 m. Three distinct heave phases were identified within the unfrozen soil. Phase 1 of the first 200 days related to penetration and heave above the groundwater table and was characterized by heave rates between 0.211 and 0.237 mm/day. Phase 2 resulted in increased ice segregation due to interaction of the freez-ing front with the groundwater table. This phase lasted from approximately day200 to day 500 and corresponded to a heave rate from 0.206 to 0.313 mm/day. Phase 3 was characterized by a further decrease in the heave rate to about 0.081 mm/day and lasted from approximately day 500 to day 1,056. 相似文献
75.
A generalized advective–diffusive equation for describing electrolytic solute transport in fine-grained soil (clay) membranes is presented. Clarification is made between the current theory and the widely cited coupled-flow theory by Yeung and Mitchell. Results of recently published experimental data are evaluated to demonstrate that the effective diffusion coefficient associated with Fick’s first law is not an appropriate independent material property for solute transport considerations in membrane soil. Three independent and experimentally attainable material properties are identified, specifically: osmotic efficiency, membrane diffusion coefficient, and hydraulic conductivity. Simple physical experiments by which these properties may be measured are described. 相似文献
76.
Dynamic instability of elastic–plastic beam is investigated by employing a three-degree-of-freedom (3-DoF) beam model. Especially, asymmetrical instability induced by symmetrical load is discussed. The asymmetrical instability is considered as a second-order buckling mode. Four types of perturbations, i.e., geometrical misalignment, material property mismatch, unsymmetry of applied load and disturbance of boundary conditions, are introduced to activate the asymmetrical responses. The asymmetrical response is characterized by a modal participation factor α2 which corresponds to an asymmetrical mode shape. Phase plane trajectories and Poincaré map are used to illustrate the chaotic characteristics of the beam response. Results show that if the perturbations are small enough, the perturbation type has negligible influence on the critical load for the occurrence of the asymmetrical instability, which implies that the asymmetrical instability is an intrinsic feature of the beam system. However, with the increase of the magnitude of the perturbations, the influence of the asymmetrical vibration is expanded to a large extension of loading parameter. 相似文献
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78.
ERP系统中采购计划管理的研究与实现 总被引:1,自引:0,他引:1
对ERP系统中采购计划的自动生成方法作了分析,提出了一种BOM数据结构的设计方法和BOM数据的采集方法,并对采购管理应该包含的功能作了讨论,最后给出了系统的整体架构和实现方案 相似文献
79.
Partchapol Sartkulvanich Taylan Altan Joerg Soehner 《Machining Science and Technology》2005,9(2):271-288
To obtain reliable results from Finite Element (FE) simulation of machining processes, it is necessary to have as input the properties of the workpiece and tool materials as well as the characteristics of the tool/chip interface. These input parameters include physical and thermal data, friction and heat transfer, and most importantly the flow stress of the workpiece material under high strain, strain rate and temperature conditions that exist during the process. This paper presents a brief review of FE simulation of machining processes, a review of the approaches used to determine the flow stress at high deformation rate, and the examples of different constitutive equations used to represent such flow stress data. A material property database (MADAMS) has been developed and provides useful information to conduct simulations of machining processes. The main objectives of the material database are to assist researchers in areas of machining analysis and material modeling and to promote collaboration between various international research groups. 相似文献
80.
基于神经网络的自适应滤波技术及其在超声检测中的应用 总被引:12,自引:0,他引:12
为满足超声无损检测和评价在新材料和新构件上应用的需求,提出了一种基于神经网络的自适应滤波器,使其兼具自适应滤波和非线性处理的能力。该滤波器是在线性自适应滤波器中引入一非线性隐含层而构成,在对该滤波器的结构和收敛性进行详细研究的基础上,实现了一种自适应噪声消除器并应用于超声检测中的材料噪声消除。实验结果证实:利用这种滤波器构成的材料噪声消除器比采用线性自适应滤波器具有更强的降噪能力。 相似文献