科创中国

Lightweight design requires an accurate life prediction for structures and components under service loading histories. However, predicted life with the existing methods seems too conservative in some cases, leading to a heavy structure. Because these methods are established on the basis that load cycles would only cause fatigue damage, ignore the strengthening effect of loads. Based on Palmgren-Miner Rule(PMR), this paper introduces a new method for fatigue life prediction under service loadings by taking into account the strengthening effect of loads below the fatigue limit. In this method, the service loadings are classified into three categories: damaging load, strengthening load and none-effect load, and the process for fatigue life prediction is divided into two stages: stage I and stage II, according to the best strengthening number of cycles. During stage I, fatigue damage is calculated considering both the strengthening and damaging effect of load cycles. While during stage II, only the damaging effect is considered. To validate this method, fatigue lives of automobile half shaft and torsion beam rear axle are calculated based on the new method and traditional methods, such as PMR and Modified Miner Rule(MMR), and fatigue tests of the two components are conducted under service loading histories. The tests results show that the percentage errors of the predicted life with the new method to mean life of tests for the two components are –3.78% and –1.76% separately, much lesser than that with PMR and MMR. By considering the strengthening effect of loads below the fatigue limit, the new method can significantly improve the accuracy for fatigue life prediction. Thus lightweight design can be fully realized in the design stage.

Three dimensional(3D)displacements,which can be translated further into 3D strain,are key parameters for design,manufacturing and quality control.Using different optical setups,phase-shift methods,and algorithms,several different 3D electronic speckle pattern interferometry(ESPI)systems for displacement and strain measurements have been achieved and commercialized.This paper provides a review of the recent developments in ESPI systems for 3D displacement and strain measurement.After an overview of the fundamentals of ESPI theory,temporal phase-shift,and spatial phase-shift techniques,3D deformation measurements by the temporal phase-shift ESPI system,which is suited well for static measurement,and by the spatial phase-shift ESPI system,which is particularly useful for dynamic measurement,are discussed.For each method,the basic theory,a brief derivation and different optical layouts are presented.The state of art application,potential and limitation of the ESPI systems are shown and demonstrated.

在以往的服务管理研究中,服务绩效的影响因素很多,然而没有文献研究员工对服务的概念性界定对服务绩效的影响.基于行为识别理论,文章提出服务认知一行为模式对一线员工的服务绩效存在影响.该研究利用旅行社业和饭店业402名一线服务员工的问卷调查数据,部分验证了所提出的假设,实证结果发现:(1)对顾客理解型服务认知一行为模式具有最高的角色外服务绩效,对工作规范型服务认知一行为模式具有最低的角色外服务绩效;(2)对工作规范型服务认知一行为模式具有最低的角色内服务绩效,对顾客理解型和手段型服务认知一行为模式具有较高的角色内服务绩效.

The 3D inverse design method,which methodology is far superior to the conventional design method that based on geometrical description,is gradually applied in pump blade design.However,no complete description about the method is outlined.Also,there are no general rules available to set the two important input parameters,blade loading distribution and stacking condition.In this sense,the basic theory and the mechanism why the design method can suppress the formation of secondary flow are summarized.And also,several typical pump design cases with different specific speeds ranging from centrifugal pump to axial pump are surveyed.The results indicates that,for centrifugal pump and mixed pump or turbine,the ratio of blade loading on the hub to that on the shroud is more than unit in the fore part of the blade,whereas in the aft part,the ratio is decreased to satisfy the same wrap angle for hub and shroud.And the choice of blade loading type depends on the balancing of efficiency and cavitation.If the cavitation is more weighted,the better choice is aft-loaded,otherwise,the fore-loaded or mid-loaded is preferable to improve the efficiency.The stacking condition,which is an auxiliary to suppress the secondary flow,can have great effect on the jet-wake outflow and the operation range for pump.Ultimately,how to link the design method to modern optimization techniques is illustrated.With the know-how design methodology and the know-how systematic optimization approach,the application of optimization design is promising for engineering.This paper summarizes the 3D inverse design method systematically.

目前存在大量异构的SOA平台,不同平台下WebService标准繁多且技术复杂,因此,异构平台Web Service的安全交互成为急待解决的问题,而SOAP消息的安全性是决定Web Service安全的重要因素.本文针对异构平台间SOAP消息的安全性问题,提出了基于WebSphere和.NET异构平台间消息传递的安全处理模型,该模型采用基于逻辑谓词的方法实现异构平台的安全策略集成,使用集成安全策略对SOAP消息进行签名和加密处理.通过实验验证,该模型保证了SOAP消息在异构平台间传递的安全性,实现了异构平台间WebService的安全交互.

Most gait studies of multi-legged robots in past neglected the dexterity of robot body and the relationship between stride length and body height.This paper investigates the performance of a radial symmetrical hexapod robot based on the dexterity of parallel mechanism.Assuming the constraints between the supporting feet and the ground with hinges,the supporting legs and the hexapod body are taken as a parallel mechanism,and each swing leg is regarded as a serial manipulator.The hexapod robot can be considered as a series of hybrid serial-parallel mechanisms while walking on the ground.Locomotion performance can be got by analyzing these equivalent mechanisms.The kinematics of the whole robotic system is established,and the influence of foothold position on the workspace of robot body is analyzed.A new method to calculate the stride length of multi-legged robots is proposed by analyzing the relationship between the workspaces of two adjacent equivalent parallel mechanisms in one gait cycle.Referring to service region and service sphere,weight service sphere and weight service region are put forward to evaluate the dexterity of robot body.The dexterity of single point in workspace and the dexterity distribution in vertical and horizontal projection plane are demonstrated.Simulation shows when the foothold offset goes up to 174 mm,the dexterity of robot body achieves its maximum value 0.164 4 in mixed gait.The proposed methods based on parallel mechanisms can be used to calculate the stride length and the dexterity of multi-legged robot,and provide new approach to determine the stride length,body height,footholds in gait planning of multi-legged robot.

分析专业图书馆实现知识服务转型的4个主要方面及对图书馆人员结构的需求,包括建设多元化数字资源保障体系、探索面向专业领域的知识服务模式、试验开展集成化知识环境建设、创建柔性灵活的团队与协作机制.结合以国家科技文献中心成员单位为代表的专业图书馆人员队伍结构,分析其人员队伍状况,阐明专业图书馆人员结构与未来发展存在业务布局、专业能力、信息技术水平、组织管理体制等方面的差距.

车辆行驶引起的桥梁振动的动力响应数据是车桥耦合振动分析中重要参数.采用超声波测速仪、录像机及桥梁动态测试仪同人工记录相结合的方法,对高速公路交通荷载各要素进行24 h连续、全面调查,记录的数据包括车型、车速、行驶车道、车辆到达时间以及每辆过桥车辆引起的桥梁动力响应数据.本调查采集了8片梁的5 650单车过桥的动响应数据,研究了交通荷载调查样本中不同梁体的动力响应数据的统计规律,全面分析了高速公路交通荷载车辆过桥引起的桥梁动力响应的时空分布规律.研究结论能够给车桥耦合振动研究及相关研究提供有益的理论指导和数据支持.

在推进农业产业化的进程中,农产品物流社会化服务体系是组织农民走向市场的桥梁和纽带,从政府职能转变不够,基地建设比较薄弱,科技服务存在"五少"问题,民间协会缺乏规范引导,龙头企业带动作用还不大,农产品市场建设不完善六个方面阐述了农产品物流社会化服务体系存在的问题,并进一步提出了完善农产品物流社会化服务体系的对策.

利用元胞自动机理论,建立了反映信息服务扩散过程的元胞自动机演化模型,分别模拟了用户的需求以及服务一需求匹配度这两个因素对信息服务扩散程度的影响,通过分析模拟结果,得出开展信息服务的一些启示.