科创中国

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.

信息期望是用户依据其经验和知识,在信息获取和利用之前、之中对信息系统功能、信息服务水平和信息产品价值属性等所确立的一种主观预期与主观判断.通过对213名网络用户进行问卷调查,发现网络用户信息期望由信息表达与服务、信息获取过程、信息内容三个维度16个指标所构成.了解与把握网络用户信息期望构成,据此来优化网络信息资源建设、信息服务和网络建设,将有助于提升用户信息体验与满意度.

探讨了体育赛事物流服务的基本内容和主要特征,构建体育赛事物流服务能力的评价指标体系,并采用信息熵和未确知测度模型方法,结合案例具体地评估了体育赛事物流的综合服务能力,为科学、客观地评价体育物流服务能力提供一种新的方法.

The existing research on improving the hydraulic performance of centrifugal pumps mainly focuses on the design method and the parameter optimization.The traditional design method for centrifugal impellers relies more on experience of engineers that typically only satisfies the continuity equation of the fluid.In this study,on the basis of the direct and inverse iteration design method which simultaneously solves the continuity and motion equations of the fluid and shapes the blade geometry by controlling the wrap angle,three centrifugal pump impellers are designed by altering blade wrap angles while keeping other parameters constant.The three-dimensional flow fields in three centrifugal pumps are numerically simulated,and the simulation results illustrate that the blade with larger wrap angle has more powerful control ability on the flow pattern in impeller.The three pumps have nearly the same pressure distributions at the small flow rate,but the pressure gradient increase in the pump with the largest wrap angle is smoother than the other two pumps at the design and large flow rates.The pump head and efficiency are also influenced by the blade wrap angle.The highest head and efficiency are also observed for the largest angle.An experiment rig is designed and built to test the performance of the pump with the largest wrap angle.The test results show that the wide space of its efficiency area and the stability of its operation ensure the excellent performance of the design method and verify the numerical analysis.The analysis on influence of the blade wrap angle for centrifugal pump performance in this paper can be beneficial to the optimization design of the centrifugal pump.

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.

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.

2011年8月31日,最高法院对外公布的《关于审理政府信息公开行政案件若干问题的规定》是最高法院对于政府信息公开的"二次立法",它对机关档案室档案信息的公开进行了司法解释,这对档案信息公开的司法救济意义重大.然而,信息公开司法解释对于申请用途举证责任的说明、与《档案法》衔接错位等情况仍然表明,档案信息公开诉讼困境的真正解决,还任重而道远.

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.

Most researches focused on the analytical stabilized algorithm for the modular simulation of single domain,e.g.,pure mechanical systems.Only little work has been performed on the problem of multi-domain simulation stability influenced by algebraic loops.In this paper,the algebraic loop problem is studied by a composite simulation method to reveal the internal relationship between simulation stability and system topologies and simulation unit models.A stability criterion of multi-domain composite simulation is established,and two algebraic loop compensation algorithms are proposed using numerical iteration and approximate function in multi-domain simulation.The numerical stabilized algorithm is the Newton method for the solution of the set of nonlinear equations,and it is used here in simulation of the system composed of mechanical system and hydraulic system.The approximate stabilized algorithm is the construction of response surface for inputs and outputs of unknown unit model,and it is utilized here in simulation of the system composed of forging system,mechanical and hydraulic system.The effectiveness of the algorithms is verified by a case study of multi-domain simulation for forging system composed of thermoplastic deformation of workpieces,mechanical system and hydraulic system of a manipulator.The system dynamics simulation results show that curves of motion and force are continuous and convergent.This paper presents two algorithms,which are applied to virtual reality simulation of forging process in a simulation platform for a manipulator,and play a key role in simulation efficiency and stability.

Longitudinal vibration,torsional vibration and their coupled vibration are the main vibration modes of the crankshaft-sliding bearing system.However,these vibrations of the propeller-crankshaft-sliding bearing system generated by the fluid exciting force on the propeller are much more complex.Currently,the torsional and longitudinal vibrations have been studied separately while the research on their coupled vibration is few,and the influence of the propeller structure to dynamic characteristics of a crankshaft has not been studied yet.In order to describe the dynamic properties of a crankshaft accurately,a nonlinear dynamic model is proposed taking the effect of torsional-longitudinal coupling and the variable inertia of propeller,connecting rod and piston into account.Numerical simulation cases are carried out to calculate the response data of the system in time and frequency domains under the working speed and over-speed,respectively.Results of vibration analysis of the propeller and crankshaft system coupled in torsional and longitudinal direction indicate that the system dynamic behaviors are relatively complicated especially in the components of the frequency response.For example,the 4 times of an exciting frequency acting on the propeller by fluid appears at 130 r/min,while not yield at 105 r/min.While the possible abnormal vibration at over-speed just needs to be vigilant.So when designing the propeller shafting used in marine diesel engines,strength calculation and vibration analysis based only on linear model may cause great errors and the proposed research provides some references to design diesel engine propeller shafting used in large marines.