A bottom-up solution for the multi-facility optimal pavement resurfacing problem

Transportation infrastructure management has been a subject of growing economic importance in recent years due to the magnitude of agency expenditures. Increasingly sophisticated methods have been developed to model pavement deterioration and solve for optimal management strategies. However, it is unclear whether these more complex methods are providing more useful results. This paper presents a simple approach for optimizing the frequency and intensity of resurfacing for multiple highway facilities. It builds upon existing optimization methods for the single-facility, continuous-state, continuous-time problem and corresponding results, which include a threshold structure for optimal solutions. This threshold structure allows for mathematical simplifications and for a straightforward optimization approach to be applied to the multi-facility case. The approach is bottom-up rather than top-down, preserving facility-specific features to develop informative budget allocation results. Application of the approach in a case study indicates that solutions are likely to be robust to deterioration model uncertainty, which is consistent with previous facility-level findings. In addition, the methodology is shown to be robust to the form of the deterioration model.     

CSR对超大型油船装载及压载舱分舱的影响

国际、国内的油运市场对超大型油船(VLCC)的需求非常迫切。油船结构共同规范(CSR)不仅对VLCC结构设计的影响是全面和系统的,还对VLCC的装载工况和压载舱分舱方案有很大的影响,而这些因素直接决定了船体的最大中拱静水弯矩。该文针对30.8万吨VLCC,对CSR进行了研究,通过装载计算,初步阐明了CSR对VLCC装载工况和压载舱分舱设计的影响。     

微型汽车发动机凸轮型线仿真优化设计及应用研究

针对微型汽车发动机低速动力不足的问题,结合发动机整机性能分析软件和多体动力学分析软件,建立了原发动机整机性能模型和单阀系多体动力学分析模型。在准确模型的基础上对凸轮型线进行了结构设计,并选出了既能满足整机性能要求又能满足单阀系多体动力学要求的最优凸轮型线组。试验结果表明,该方法可以方便找出最优的凸轮型线范围,减少了试验次数,降低了开发成本。     

大型客车门窗口变形分析与优化

提出了大客车车身优化门窗对角线变形量的方法.通过对门窗对角线变形量的灵敏度分析结果进行适当处理,筛选出部分梁截面尺寸作为设计变量对车身结构进行了尺寸优化.优化结果表明,在质量略有增加的情况下,车身结构的模态特性基本保持不变,刚度特性得到大幅提升,优化后的车身结构满足了各项设计要求.     

总纵强度耦合作用的船体板架强度计算方法

船体板架局部强度计算时，由于受到总纵弯曲的影响，实际上极架都是处在复杂弯曲状态，以往板架局部强度校核时未考虑这种影响。本文采用有限元方法原理，考虑总纵强度对局部强度的耦合影响，推导和发展了板架局部强度校核方法。对比计算表明，本方法可用于实用计算。     

Studies on the block positioning metrics system for the hull erection stage

In ship hull production, the accuracy of management activities is extremely important. The block positioning operation in the erection stage is a key process in such management. The quality of the block positioning determines not only the accuracy of the final hull, but also the productivity and cost at the erection stage. We have previously proposed the basic concepts of computer-aided accuracy management. Accuracy management activities consist of "accuracy planning activities" and "accuracy measurement activities." Accuracy measurement activities involve checking and coping with inaccuracy. We have also proposed a system of accuracy measurement metrics: one is accuracy for completion (e.g., straightness, flatness), and the other is accuracy for construction (e.g., the relative joint shapes of each part). This paper explains the detailed accuracy metrics for a block positioning operation in the erection stage. The quality of the block positioning operation is estimated by this system: the accuracy of the completed hull can be evaluated by the concept of tolerance, and the accuracy of the construction process can be evaluated by the concept of labor costs. The prototype of this accuracy metrics system is then implemented. This metrics system is combined with the optimization software program iSIGHT to decide the best block positioning process. Then some examples of the block position optimizing process are shown. Received: November 2, 2001 / Accepted: December 6, 2001     

非线性汽车行驶平顺性模型的神经网络优化

本文运用离散生成随机路面输入的方法，在时城上对11自由度非线性整车行驶平顺性模型进行了分析研究，并在此 以径向基函数神经网络对悬架参数进行了优化计算。模型及算法合理准确，为汽车行驶平顺性的进一步研究提供了有价值的参考方法。     

汽车乘员安全约束系统的优化

本文利用ＭＡＤＹＭＯ软件建立了包括台车、安全带约束的乘员前碰仿真模型并通过试验验证了模型的正确性。利用该模型对乘员安全约束系统的优化问题进行了研究。对几种优化方法应用于乘员约束系统的效果进行了评价，提出了改进约束系统的建议。     

潜艇外部耐压液舱结构优化设计

提出了一种优良实用的准同心圆式潜艇外部耐压舱结构型式,并给出了这种结构基于近似解析法和基于有限元应力分析的结构优化设计方法。曲型实例表明,准确同心圆式结构优化设计方案优于传统结构设计方案。     

四轮驱动燃料电池汽车动力系统参数匹配与优化

针对某多电机双能源四轮驱动燃料电池汽车动力参数匹配进行了研究。根据其整车结构、行驶工况以及控制策略,对动力系统参数进行初步选择,并以动力系统各部件尺寸最小为目标函数、相应参数为设计变量、整车动力性能为约束条件进行优化计算,得出动力传动系统合理的参数匹配,不仅动力性完全满足设计要求,而且经济性得到提高。