Uncertain optimal model and solving method to platform scheduling problem in battlefield

The platform scheduling problem in battlefield is one of the important problems in military operational research.It needs to minimize mission completing time and meanwhile maximize the mission completing accuracy with a limited number of platforms.Though the traditional certain models obtain some good results,uncertain model is still needed to be introduced since the battlefield environment is complex and unstable.An uncertain model is prposed for the platform scheduling problem.Related parameters in this model are set to be fuzzy or stochastic.Due to the inherent disadvantage of the solving methods for traditional models,a new method is proposed to solve the uncertain model.Finally,the practicability and availability of the proposed method are demonstrated with a case of joint campaign.

Modal Identification of Offshore Platforms Using Statistical Method Based on ERA

Identification of modal parameters of a linear structure with output-only measurements has received much attention over the past decades. In the paper, the Natural Excitation Technique (NExT) is used for acquisition of the impulse signals from the structural responses. Then Eigensystem Realization Algorithm (ERA) is utilized for modal identification. For disregarding the fictitious ‘computational modes', a procedure, Statistically Averaging Modal Frequency Method (SAMFM), is developed to distinguish the true modes from noise modes, and to improve the precision of the identified modal frequencies of the structure. An offshore platform is modeled with the finite element method. The theoretical modal parameters are obtained for a comparison with the identified values. The dynamic responses of the platform under random wave loading are computed for providing the output signals used for identification with ERA. Results of simulation demonstrate that the proposed method can determine the system modal frequency with high precision.

Finite Element Method for Design of Reinforced Concrete Offshore Platforms

A design method of reinforced concrete (R. C.) offshore platforms with nonlinear finite element analysis is proposed. According to the method, a computer program is developed. In this program nonlinear constitutive relationships and strength criteria of concrete and steel bars are included, and the progressive cracking and crushing of the concrete are taken into account. Based on the stress distribution obtained by the nonlinear finite element analysis, the amount of reinforcement in the control sections can be computed and adjusted automatically by the program to satisfy the requirement of the design. The amount of reinforcement required in the control sections, which are obtained with the nonlinear finite element analysis, is agreeable to that obtained in the experiment. This shows that the design method of R. C. offshore platform with the nonlinear finite element method proposed by the authors is reliable for practical use.

Simplified Computation Method of Vibration Characteristics of Jacket Platforms

In this paper a simplified computation method of natural frequency of jacket platforms is given. Shear, bending and rotary inertia effects are considered in the equation, while the jacket shape, rotary inertia and centralized mass of the platform top are all determined by using a coefficient-revising method.

A bottom-up method for module-based product platform development through mapping,clustering and matching analysis

Designing product platform could be an effective and efficient solution for manufacturing firms. Product platforms enable firms to provide increased product variety for the marketplace with as little variety between products as possible. Developed consumer products and modules within a firm can further be investigated to find out the possibility of product platform creation. A bottom-up method is proposed for module-based product platform through mapping, clustering and matching analysis. The framework and the parametric model of the method are presented, which consist of three steps:(1) mapping parameters from existing product families to functional modules,(2) clustering the modules within existing module families based on their parameters so as to generate module clusters, and selecting the satisfactory module clusters based on commonality, and(3) matching the parameters of the module clusters to the functional modules in order to capture platform elements. In addition, the parameter matching criterion and mismatching treatment are put forward to ensure the effectiveness of the platform process, while standardization and serialization of the platform element are presented. A design case of the belt conveyor is studied to demonstrate the feasibility of the proposed method.

An Application of Direct Ritz Method for Random Seismic Responses of Jacket Platforms

In this paper, the jacket platform is simulated by a non-uniform cantilever beam subjected to axial force. Based on the Hamilton theory, the equation of bending motion is developed and solved by the classical Ritz method combined with the pseudo-excitation method for random responses with non-classical damping. Usually, random responses of this continuous structure are obtained by orthogonality of modes, and some normal modes of the structure are needed, causing inconvenience for the analysis of the non-uniform beam whose normal modes are not easy to be obtained. However, if the pseudo-excitation method is extended to calculate random responses by combining it with the classical Ritz method, the responses of a non-uniform beam, such as auto-PSD function, cross-PSD and higher spectral moments, can be solved directly avoiding the calculation of normal modes. The numerical results show that the present method is effective and useful in aseismic design of platforms.

Subsystem model-based close-loop grey-box identification method for hydraulic stewart platform

In order to solve the problem of difficult modeling and identification caused by time-variable parameters,multiple inputs and outputs and unstable open loop,a subsystem model-based close-loop grey-box identification method was put forward when consider the main coupling effects of hydraulic Stewart platform.Firstly,the whole system is divided into three TITO(Two Input Two Output) subsystems according to the characteristics of the pseudo-mass matrix,hence transfer function matrix model of the subsystem can also be found.Secondly,since the Stewart platform is unstable,the close-loop transfer model of the subsystem is derived under the proportional controllers.The inverse M serial is adopted as the identification signal to get the experimental data.All parameters of the subsystem are determined in close-loop indirect identification by PEM(Prediction Error Method).Finally,a case study validates the correctness and effectiveness of the subsystem model-based close-loop grey-box identification method for hydraulic Stewart platform.

复杂受荷下盾构隧道原型结构试验平台的研发与实证

盾构隧道结构在全寿命周期中往往将面临诸多复杂荷载状态,如注浆、偏载、偏转等非对称偏不利工况。为验证结构在这些复杂荷载状态下的适用性,探究结构力学性能,开展足尺原型结构试验研究往往是最为直接而有效的手段。既有原型试验主要关注隧道结构在简单对称荷载条件下的力学性能,鲜有关注复杂非对称荷载状态。为拓展原型试验的适用范围,提出了适用于不同断面盾构隧道结构的原型试验平台和用于模拟复杂荷载状态的试验荷载设计方法。该方法适用于任意加载点布置和液压站分组的试验系统,可对注浆、偏载、偏转等复杂荷载状态下结构响应进行精确模拟。通过类矩形盾构隧道、双圆隧道和圆形隧道的偏载原型结构试验研究,验证了试验平台和试验荷载设计方法的适用性。进一步针对试验关键参数的分析表明,控制目标权重系数的调整能有效满足不同的试验模拟要求;基于试验荷载设计方法优化的迭代算法能有效考虑计算模型或边界支承条件的非线性;环箍钢绞线和千斤顶的组合加载模式能将拟合误差水平降低至千斤顶加载模式的1/5,但需要删去部分加载点使试验荷载合理且适用;对于越复杂的结构和荷载,精确模拟结构状态需要的试验系统独立荷载组数越高,对试验平台的要求也越高。

基于Sakai平台的过程考核教学模型与应用

过程考核是科学评价一门课程教学质量的关键,已成为教育领域关注的热点。如何将过程考核科学地渗入到一门课程的教学过程中,对于提升课程教学的学习质量和效率尤为重要。基于Sakai平台,提出过程考核“五力”教学模型,该模型包括作业、测验、讨论、期中、拓展五个考核环节。在课程教学应用中,“五力”模型过程考核教学模式,激发学生课余时间主动学习的兴趣,拓展学生的知识面,提升课程知识点的学习质量,同时有效提高教师过程考核的效率。

超宽窄行蕉园起垄机抛土机构设计与试验

目的在查阅大量国内外有关起垄机构的研究文献基础上,结合新型蕉园种植模式和农艺要求,设计一种蕉园起垄机抛土机构,实现蕉园起垄机械化作业。方法对抛土起垄机构主要部件进行建模仿真,应用EDEM对抛土起垄过程进行仿真,以导向罩角度、叶轮转速、叶片宽度及叶片偏角作为试验因素,将抛撒距离和土壤集中率作为评价指标,进行单因素和正交旋转组合仿真试验,探究因素对抛土起垄机构作业性能的影响。最后利用Design-Expert数据处理软件对仿真数据进行分析,得到作业最优组合参数,并将最优参数组合来制作样机进行平台试验。结果通过仿真试验与平台试验对比,得出最佳起垄组合参数:导向罩角度为30°,叶轮转速为275 r/min,叶片宽度为82 mm、叶片偏角为–7.5°;罩角度为62°,叶轮转速为314 r/min,叶片宽度为82 mm、叶片偏角为–7.5°,最终得到仿真结果中土壤集中度分别为73%和81%,抛撒距离为2081.29 mm和979.2 mm,平台试验验证结果在合理区间范围内。结论根据仿真与平台试验结果的对比,得到机构抛土效果满足蕉园的起垄要求的最佳参数组合,为“超宽窄行”蕉园起垄机械设计提供了参考依据。

基于微信平台的中医内科学PCBL教学模式应用研究

探讨基于微信平台的以问题为中心(PBL)教学方法与以案例为基础(CBL)的教学方法联合使用(即PCBL教学模式)在中医内科学专业本科生教学中的应用效果。选取北京中医药大学2019级京华传承班及2020级京华传承班中医学专业本科学生共64名,分为观察组和对照组,观察组采用基于微信平台的PCBL教学模式,对照组采用传统教学方法,对2组基础理论知识和综合运用能力进行考核,并以问卷调查形式评价教学效果。结果表明,观察组基础理论知识及综合运用能力的考核成绩均优于对照组(P<0.05),观察组问卷调查满意度高于对照组(P<0.05)。基于微信平台的PCBL教学模式可激发学生学习的兴趣和主动性,有助于本科生临床思维能力的培养及教师教学水平提升。

数智驱动的零售电商平台供应链发展研究

选取国内零售电商企业为研究对象,基于供应链视角,采用熵值法及描述性统计方法对当前数智驱动背景下零售电商平台供应链发展新格局对经济市场的辐射作用,以及国内零售电商上市公司供应链发展情况进行研究.研究结果发现,数智驱动下的零售电商企业供应链整体发展稳中求进,也证明了数智化对供应链发展具有重要的推动作用,数智驱动下的供应链仍然有发展进步空间与实际研究价值,提出电商平台供应链发展建议,对于零售电商企业具有实际参考价值.

UVW对位平台运动学分析及轨迹规划

为控制UVW对位平台匀速运动,对平台做了运动学分析,并针对速度下降问题,设计轨迹规划方案。首先,以自由度为基础建立平台二维平面模型,求解位置正反解公式,分析奇异位形,构建三维工作空间。然后,对常用的同步定速法做轨迹分析,由运动轨迹散点图可知:当旋转角绝对值|θ|增大至15°时,平台运动末端速度与初始速度比值下降为0.935,意味着|θ|增大可降低平台运动速度。最后,结合平台自由度与速度变化规律,设计出等角速度瞬心法。通过对比可知,使用等角速度瞬心法平台运动速度保持恒定,消除了旋转角θ引起的速度下降。

高洁净度超光滑非球面的自动化干涉检测方法

为了实现应用于高能激光等领域对表面洁净度有着极高要求的超光滑非球面检测,排除检测人员带来的洁净度与空气扰动的影响,研究了高洁净度超光滑非球面的自动化干涉检测方法。通过建立补偿干涉法非球面失调量与波前像差之间的灵敏度矩阵,实现利用波前像差求解被测非球面失调量。以理想干涉系统的离焦、彗差与像散为优化目标,进行反馈控制,实现被测非球面的自动化调整,进而实现高洁净度超光滑非球面的自动化干涉检测。实验结果表明,在干涉图可测范围内,利用灵敏度矩阵通过几步迭代即可实现非球面失调量的收敛。结合Stewart六自由度调整台,分别实现2μm精度的平移误差调整、2"精度的光轴自动化对准,最终完成被测非球面的精密调整,实现高洁净度超光滑非球面的自动化干涉检测。采用灵敏度矩阵与六自由度调整的非球面自动化干涉检测方法可实现被测非球面失调量的快速求解与自动调整,降低人员和环境带来的扰动影响,提高了非球面的检测速度,并实现了高洁净度超光滑非球面的自动化干涉检测。

电液3-UPS/S并联稳定平台参数振动特性分析

针对电液3-UPS/S并联稳定平台驱动液压缸的压力脉动所产生的参数振动,建立了稳定平台的参数振动方程并利用多尺度法求解了主共振响应与组合共振响应的一次近似解;分析了主共振与组合共振响应特性以及振动幅值在初始工作空间内的变化规律,最后采用四阶龙格库塔法与模态试验对参数振动模型进行验证。结果表明:数值解与理论解之间的最大误差为4.20%,固有频率理论值与试验值之间的最大误差为4.66%,可验证参数振动模型的正确性。

挖掘机回转特性分析与优化

针对某型挖掘机市场作业出现回转启动抖动、制动锁不住现象,进行厂内回转试验研究。考虑液压因素所致,故搭建试验平台,采集回转马达压力,陀螺仪采集回转运动过程中的角速度、角加速度以及制动时间、制动角度,振动传感器采集驾驶室悬置主被动侧加速度信号,评估回转支承抖动对驾驶室悬置隔振性能的影响,进而研究驾驶室噪声。结果表明,试验样机振动噪声性能较好,工作装置单动作、回转性能与高端机型差距不大,铲斗内收单动作时间增加16.0%,斗杆内收时间增加13.3%,动臂提升加回转时间增加14.6%,液压缸行程减小9.6%,铲斗提升高度下降7.9%,装车高度稍低。提出的试验方法可以建立切向力与回转角度关系,解决试验之前拉力计需与铲斗回转方向共线的问题。采用PID控制方法,优化压力波动范围,使得回转过程中稳定性好,抖动现象有所改善。

海上通信中继平台阵位配置优化模型

针对海上通信中继装备的综合运用,结合最大通信距离、目标威胁分布等条件,提出中继平台阵位配置优化模型,解决通信中继平台阵位的最优部署问题。该模型基于中继平台航路起点到阵位点距离最短原则,对通信距离、目标威胁约束下的中继平台阵位配置问题进行建模,利用凸优化方法获得阵位配置最优解的解析形式。最优解具有较强的可解释性,并且求解过程避免使用传统的迭代式或启发式求解方法,具有计算量小的优点。算例分析表明,对任务平台和威胁目标的不同位置分布情况,可以快速获得阵位配置最优解。

基于网络认知行为疗法的养老护理员腰背痛干预方案的构建

目的构建一种基于网络认知行为疗法(ICBT)的养老护理员腰背痛干预方案,为养老护理员腰背痛患者管理提供新思路。方法通过前期文献回顾及焦点小组访谈,初步拟定干预方案。采用两轮德尔菲专家函询法,根据专家意见对方案条目进行修改。结果两轮函询共咨询16名专家,有效回收率均为93.75%,专家权威系数分别为0.83、0.86,肯德尔和谐系数分别为0.256、0.139(P<0.05)。第2轮函询中,各条目变异系数为0.00~0.20,重要性评分为4.13~4.87分,最终形成一种基于ICBT的养老护理员腰背痛干预方案,包括3个一级指标、12个二级指标、24个三级指标及48个四级指标。结论该研究所构建的基于ICBT的养老护理员腰背痛干预方案可信、可行,能够为养老护理员腰背痛干预提供参考。

3UPU-UP并联平台可操作性与工作空间分析

6支链并联平台存在着复杂的位置约束,并且当控制算法失效时对机械结构容易造成损坏,因此,针对一种3UPU-UP并联平台对其进行运动学可操作性与工作空间分析。首先通过矢量法与运动学的分析,得出了3UPU-UP并联平台运动学模型,以此为基础,首次将串联机械臂可操作度的评价指标与3UPU-UP并联平台的机构结构特性相结合,对3UPU-UP并联平台的可操作度进行了计算、分析和可视化处理;并将蒙特卡洛法与正运动学相结合对并联平台的工作空间进行了计算、分析和可视化处理。能够更加直观、完整表述并联平台的可操作度和工作空间。研究成果为3UPU-UP并联平台的设计提供了理论依据并证实其理论上的可行性。

网络隐私权视域下的众筹平台隐私政策评价

对不同类型众筹平台的隐私政策进行科学评价,据此改善平台对用户网络隐私权的保障措施具有积极意义。文章基于国内外相关政策构建众筹平台隐私政策评价体系,利用层次分析-熵值定权法对指标进行赋权,并选取主流众筹平台开展实证研究。研究结果显示:我国众筹平台的用户网络隐私权保障情况整体不容乐观,个体差异巨大、保障水平参差不齐,对安全请求权和隐私利用权的保障效果优于对隐私知情权和隐私控制权的保障,需从规范隐私监管机制、建立分类隐私保护措施和优化隐私保护政策等层面进行优化。