影响Ni—P合金镀层结合力因素的研究

本文用自制的划痕试验机研究了影响Ni-P合金镀层结合力的因素,分析了划痕试验时锭层开裂、剥离的情况,观察了镀后加热温度、基体硬度等对划痕形貌的影响规律,并用B-W公式计算了试样的结合力。结果表明,镀后加热温度越高,镀层厚度越厚,基体硬度越高,结合力越大。     

Strategy-Based Forecasting Model for Civil Airlines

Airlines usually pay more attention tO maintenance cost for efficiency improvement and consumption reduction．However，airlines，especially the domestic airlines，Can hardly predict the cost exactly due to the uncertainty and complexity until now．In practice，the cost is calculated by collecting and calculating the invoices afterwards．To settle the problem，a maintenance cost forecasting model is proposed in this paper．Maintenance activities are classified into scheduled maintenance and unscheduled maintenance．Scheduled maintenance is periodic，in which the required materials and man-power hours can be obtained properly in advance．Nevertheless，it is impossible to acquire the necessary in formation of unscheduled maintenance．According to the specific characteristics of each，Activity-Based Costing(ABC)and Cost Estimating Relationships(CERs)are introduced to attack the building of forecasting models，respectively．Then practical cases，the 3C check of MD-90 and the engine shop visit are adopted tO verify the cost forecasting models proposed．The results show that the models not only can predict the actual maintenance cost successfully，but also are helpful tO drawing up the maintenance program and managing the maintenance funds efficiently．     

NEURAL NETWORKS PREDICTION FOR SEISMIC RESPONSE OF STRUCTURE UNDER THE LEVENBERG-MARQUARDT ALGORITHM

Activecontrolandsemi activecontrolarenewapproachestoseismichazardmitigationofstructure .Whileinactivecontrolorsemi activecontrol ,mea surementofstructurestate ,transmissionandcalcu lationofsignalandinflictionofcontrolforcerequiretime ,moreover ,controlforceiscalculatedaccordingtotheseismicresponseofstructureinlastepoch ,sothecontrolforceinactivecontrolorsemi activecontrolmaybedistortedduetotime delay .Suchdistortionusuallyincreasestheseismicresponseofstructureandmakesstructuremoredangerous[1-3…     

Possibility of Strategic Alliance from Competition： A Game Analysis

The possibility for two competitive firms to form a strategic alliance was quantitatively analyzed with the game theory. The strategic alliance could be formed in an infinitely repeated game with complete information or a finitely repeated game with incomplete information. In the former situation, the discount ratio is important. If the discount ratio is large enough, alliance would be a possible solution. In the latter situation, the bigger the possibility of the rationality is, the more possible is for both firms to make strategic alliance.     

Modified Weighting for Calculating the Average Concentration of Non-Point Source Pollutant

The concentration of runoff depends upon that of soil loss and the latter is assumed to be linear to the value of EI that equals the product of total storm energy E times the maximum 30-min intensity，I^30 for a given rainstorm．Usually，the maximum accumulative amount of rain for a rainstorm might bring on the maximum amount of runoff，but it does not equal the maximum erosion and not always lead the maximum concentration．Thus，the average concentration weighted by amount of runoff is somewhat unreasonable．An improvement for the calculation method of non-point source pollution load put forward by professor Li Huaien is proposed．In replacement of the weight of runoff，E1 value of a single rainstorm is introduced as a new weight．An example of Fujing Rive rwatershed shows that its application is effective．     

低轮轨力转向架车轮辐板形状优化的可行性研究

增加列车轴重是提高铁路货运能力的一种有效手段,但货车轴重的增加,必然引起一系列的强度问题。采取把车轮直径由840mm增大为915mm,可以保证强度要求,但也增加了轮对死重。本文探讨了一种在不增加轮径的前提下,仅通过对车轮辐板进行形状优化,就可使其在25t轴重下可靠工作的优化设计方法。结果表明,对车轮轮辐断面形状优化后,可较大幅度地降低其温度应力,有可能使840mm车轮在25t轴重下的应力接近甚至低于原结构在21t轴重下的应力水平。     

飞机除冰液对停机坪水泥混凝土的影响

通过除冰液成分分析、混凝土试件除冰液浸泡实验、物相分析和冻融理论分析，探讨了剥落损坏发生的原因和机理。研究发现除冰液和水泥混凝土之间并不会发生化学反应；除冰液的渗入会增加混凝土内的水压力、渗透压、蒸气压差异和温度梯度。结果表明，除冰液参与下的剥落属于物理损坏，主要由冻融循环引起；除冰液的存在和入渗加剧了混凝土表面层的冻融剥落发生。建议从减少除冰液的用量、使用范围、与混凝土的接触时间，以及混凝土的抗冻等方面进行剥落防治。     

70%低地板轻轨车建模及动力学分析

建立了70％低地板轻轨车的动力学计算模型，对建模过程中非动力转向架、独立车轮、车体间的铰接结构等关键部件的处理方法进行了分析，并运用SIMPACK多体动力学仿真软件分析了该计算模型的运动稳定性、曲线通过性及运行平稳性等动力学性能。结果表明，该车具有良好的蛇行运动稳定性、曲线通过性及运行平稳性，能够满足运行的要求。     

机场跑道长度可靠性设计方法

将可靠性理论引入跑道长度计算,对有关变量作了统计分析,获得了空气相对密度、风速、驾驶误差系数、着陆接地点到跑道端的距离等变量的分布规律。采用遗传算法和重要抽样法进行了跑道长度可靠度分析,提出了一种基于可靠性理论的跑道长度设计方法,对永备机场进行了可靠性评价,其平均失效概率是4 75×10-4,实际失效概率为2×10-43×10-4,两者比较接近。计算结果表明可靠性方法对跑道长度设计和安全性评价是可行的。     

悬索桥的竖向振动分析与锚索弹性变形的影响

本文对单跨加劲式悬索桥竖向振动进行了分析。在Галёркин法的基础上导出了一种便于计算的简化计算方法。本文还分析了锚索弹性变形对悬索桥振动特性的影响。