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861.
A Method of Clustering Components into Modules Based on Products' Functional and Structural Analysis
Modularity is the key to improving the cost-variety trade-off in product development. To achieve the functional independency and structural independency of modules, a method of clustering components to identify modules based on functional and structural analysis was presented. Two stages were included in the method. In the first stage the products' function was analyzed to determine the primary level of modules. Then the objective function for modules identifying was formulated to achieve functional independency of modules. Finally the genetic algorithm was used to solve the combinatorial optimization problem in modules identifying to form the primary modules of products. In the second stage the cohesion degree of modules and the coupling degree between modules were analyzed. Based on this structural analysis the modular scheme was refined according to the thinking of struc- tural independency. A case study on the gear reducer was conducted to illustrate the validity of the presented method. 相似文献
862.
装车地直达列车开行方案优化模型 总被引:3,自引:1,他引:2
铁路货物运输在国民经济增长和发展过程中起着越来越重要的作用,而装车地直达运输是一种现代和高效的车流组织形式。它不但能够加快货物送达、加速车辆周转,而且可以减轻编组站作业负担、降低运输成本。本文对装车地直达列车开行方案问题进行了研究。在分析组织装车地直达列车的可能性、合理性及费用参数选择的基础上,构建了装车地直达列车开行方案非线性0-1规划模型。模型中充分考虑了车流在装车地的各种组合方案,并将运输与库存成本纳入同一目标函数,以物流系统成本最优来确定货物列车开行方案。构建的模型能够更全面地描述装车地车流的各种组合,最后给出的构模实例对模型的有效性、合理性进行了验证。 相似文献
863.
SHEN Ji-hong ZHAO Xi-ren College of Science Harbin Engineering University Harbin China College of Automation Harbin Engineering University Harbin China 《船舶与海洋工程学报》2002,1(1):65-68
GM(1, 1) is generally used in Grey System Theory which constructs an Ordinary Differential Equation for given se-ries. It is effective for monotone series, and its simulating effect is good and error is small. However, If the series dosen' t havea property of monotone, the simulating effect of GM(1,1) is not fine, and its error gets bigger. In this paper, we use GM(2,1) to handle the oxcillation series, which uses the Method of Minimum Squares in determining the uncertain parameters.The 相似文献
864.
针对SS9改型机车夏季运用中出现机械间温度较高的问题,提出了通风降温优化方案。并通过CFD软件分析计算及实车试验,结果证明通风降温取得了较好的效果。 相似文献
865.
Organically complexed and total dissolved copper and nickel were measured in the Thermaikos Gulf waters during winter 1998. Total concentrations ranged from 1.13 nmol/L to 7.02 nmol/L for copper and from 3.04 nmol/L to 9.50 nmol/L for nickel. The C18 Sep-Pak solid phase extraction technique was used in order to determine the amount of copper and nickel complexed with the hydrophobic component of the dissolved organic matter (DOM). Up to 32.4% of total copper and 4.57% of total nickel were complexed with the DOM extracted by C18. By applying HPLC analysis it was shown that the majority of the organic compounds retained by C18 had intermediate to low polarity. Using the absorbance ratio a254/a436 it was possible to unravel that humic substances of both terrestrial and marine origin were present in the Thermaikos Gulf and their distribution followed the dilution of riverine waters. Moreover our results indicated that organic binding of both Cu and Ni was stronger with the hydrophobic compounds of terrestrial origin than with those of marine origin. 相似文献
866.
基于FPGA的MVB1类设备网卡的设计 总被引:12,自引:0,他引:12
考虑到MVB1类设备网卡支持简单的过程数据传送(功能代码为0~4)和设备状态响应(功能代码15),不支持消息数据、过程数据强制功能的情况,提出利用FPGA(现场可编程门阵列)开发MVB1类设备网卡。这样,在完成通信功能的同时,可以无需外加CPU即完成一些简单的IO、AD等功能,也可以设计出总线方式与CPU相连。实践证明MVB1类设备网卡采用PC104接口与宿主CPU连接,具有110个256位的过程数据通信能力;用FPGA开发MVB1类设备网卡比用MVBC芯片更具优势。 相似文献
867.
大型结构温度场实时监测系统 总被引:1,自引:0,他引:1
结构健康监测在土木工程学科中具有重要的理论意义和工程价值。其中,温度监测是大型结构健康监测与评估的一个重要方面。以芜湖长江大桥健康监测中的铁路桥连续梁部分分布式温度监测为背景,开发了基于数字式温度传感器DS18B20的大型结构温度场实时监测系统。该系统已经成功地应用在芜湖长江大桥和郑州黄河大桥健康监测系统中,实现了对桥梁结构温度场的实时监测。应用情况表明:该系统具有实时性强、可靠性和准确性高、性价比高、通用性好等特点,对其他大型结构的温度场监测具有重要的参考价值。本文介绍DS18B20的特点、工作流程和系统的软硬件实现技术,并对系统的现场应用情况进行总结。 相似文献
868.
A linked hydrodynamic mineralization model is described and used to evaluate offshelf fluxes and fractionated mineralization of particulate phytogenic materials in the coastal upwelling system of the Rías Baixas (NW Spain), under three different typical situations of the upwelling season. The simulations made indicate that the intensity of upwelling controls: (a) net community production (NCP); (b) particulate organic matter (POM) accumulation; (c) in situ mineralization; and (d) matter export in the ‘Rías Baixas.’ Under strong upwelling conditions, there is an important horizontal offshelf flux, having only a small mineralization effect on NCP; if weak upwelling conditions are simulated, POM export is dramatically reduced and in situ mineralization is significantly enhanced; finally, under average upwelling conditions, the offshelf export of POM is about one third of the POM accumulation inside the domain, evidencing its importance in the productivity enhancement of near-shore areas. According to our sensitivity tests, the net vertical velocity (water velocity plus sinking velocity) has a critical role in the C/N/P stoichiometry of POM. 相似文献
869.
铁路信号站间信息的安全传输方案研究 总被引:2,自引:0,他引:2
安全是铁路运输的永恒主题。在信息化的浪潮中,计算机控制系统在铁路中得到了广泛的应用。本文研究的结合多种站间通信方式的通过安全散列算法-SHA-1来保证站间信息的安全传输方案,为进一步提高计算机控制系统功能,完善站间信息的传输方式及传输容量,适应今后的发展奠定了基础。 相似文献
870.
DJ_1型机车主变压器油箱盖焊接填充材料的选择 总被引:1,自引:0,他引:1
刘海涛 《电力机车与城轨车辆》2004,27(3):32-33,36
介绍了DJ_1型机车主变压器油箱箱盖上的不锈钢材质间的焊接性,利用舍夫勒组织图对焊接过程中同种材质焊接与异种材质焊接时填充材料的选择进行了分析。 相似文献