厦门海域落水集装箱漂移路径的数值模拟

对落水集装箱的受力和进水淹没过程进行分析,细化落水集装箱风致漂移系数与淹没率的线性关系。并以“SITC PYEONGTAEK”轮落水集装箱为例,结合区域海洋模式模拟的海流数据,用拉格朗日法和蒙特卡洛随机扩散相结合的粒子追踪法建立集装箱追踪模型模拟集装箱的漂移轨迹,再利用网格化统计方案对零散分布的粒子进行概率统计,分析掉落集装箱的漂移位置。通过实际案例中集装箱落水后的漂移轨迹对模型进行验证,表明该模型模拟得到的轨迹点与海上发现的漂浮集装箱点位基本吻合,说明该模型有助于快速锁定漂移区域,减少由落水集装箱带来的风险,增加航行单位对落水集装箱漂移轨迹的预测准确性,为集装箱落水港区及周边水域的通航安全提供保障。

基于微形变分析的电容式MEMS加速度计温漂误差精密估计方法

针对传统的电容式微机电系统(micro-electro-mechanical system,MEMS)加速度计(capacitive MEMS accelerometers,CMA)温漂误差(temperature drift error,TDE)补偿方法存在非精准溯源TDE致使TDE估计精度低、反复尝试估计模型构型导致构建过程复杂繁琐的问题,提出基于微形变分析的CMA TDE精密补偿方法。首先,通过微形变分析内部结构精准溯源TDE,基于径向基函数神经网络(radial basis function neural network,RBFNN)构建改进型TDE精密估计模型;其次,基于专家经验和模糊理论提出Expert-Fuzzy辅助决策下TDE估计模型辨识方法,为改进模型提供有效的构型指导;然后,设计升温试验测试CMA,构建传统模型和改进模型并通过对比其输出偏置稳定性评估TDE估计性能。实验结果表明,改进模型构建过程大大简化,补偿后CMA偏置稳定性提升约35%。本方法能够更加精准地估计TDE,有效解耦硅基材料的温度依赖性并提升CMA的环境适应性。

一种光纤陀螺全温启动漂移补偿方法

本文提出了一种光纤陀螺全温启动温度漂移补偿方法。首先,采用三个惯性传感器内置的温度计信息组成的多维温度变量构建寻北仪内部的温度场,然后使用支持向量回归(SVR)来构建多维温度变量与光纤陀螺温度漂移误差的补偿模型,最后应用麻雀搜索算法(SSA)来调优SVR模型核参数来提高温度误差补偿模型的精度和泛化能力。寻北实验验证了所提方法的有效性:将寻北仪启动阶段的精度从0.0209°提高到0.0101°,使其启动阶段的性能与稳定阶段的性能接近,并提升了其在不同初始温度下的快速响应能力。

公司制社会企业可持续性的制度困境及其破解

公司制社会企业可持续性契合中国“高质量发展”主题与全球化“公司可持续性”议题。现行法框架下,公司制社会企业法人地位与认证制度的双重不匹配、内部治理机制和外部监督机制的不完善以及责任规则的缺位构成其可持续性的制度障碍。应从体系化保障公司制社会企业主体资格可信性、针对性设计公司社会目的内部治理机制、压实认证机构的专门化监督、明确公司社会目的漂移的法律责任等四个方面改善公司制社会企业可持续性关键制度缺失,在法治轨道上推进公司制社会企业可持续性。

连续激光载波同步系统的慢漂抑制

高精度同步系统是加速器产生高品质束流的关键因素之一,基于清华大学已有的连续激光载波同步系统,对不同接收端之间参考微波信号相位差的长时漂移,即同步系统慢漂进行了研究,提出了一种基于接收端参考微波信号幅值的电光调制器(EOM)偏置电压控制方法抑制慢漂。采用该方法后,清华大学甚高频光阴极电子枪测试平台L波段(1300 MHz)同步系统慢漂被抑制到10.45 fs@24 h,清华大学汤姆逊散射装置(TTX)S波段(2856 MHz)同步系统慢漂被抑制到10.53 fs@24 h,并且该方法可以使整套同步系统工作于室温环境,有效地提高了同步系统对工作环境温度的适应性。

基于改进神经网络的TMR磁传感系统温漂校准方法

由于环境以及自身元件的发热等因素的影响,TMR磁传感系统实际工作温度会发生一定程度的波动。随着温度的升高或降低,TMR磁传感系统的实际输出会产生一定的误差,出现输出的温度漂移现象。为了抑制温度漂移对TMR磁传感系统的影响,采用反向传播(BP)神经网络对系统输出的温度漂移现象进行补偿,并利用遗传算法(GA)对BP神经网络进行优化,通过对补偿前后数据的对比,使TMR磁传感系统的输出温漂大幅下降了2个量级,得到了较为理想的效果,提升了TMR磁传感系统的性能和可靠性。

喷杆式喷雾机降低药液喷雾漂移技术研究

通过对喷杆式喷雾机降低药液喷雾漂移技术的研究,加强植保工作者在农作物保护过程中对环境保护的重视,在提高喷雾效率的同时更要注重环境保护。通过对喷杆式喷雾机降低药液喷雾漂移的先进技术分析,对植保机械产品研发工作者在产品开发中的技术方向提供启发。

卫星跳波束系统定时提前算法

文中主要介绍了卫星跳波束系统中的用户定时提前调整算法,包括用户定时提前计算和用户定时补偿机制,并考虑在定时漂移后设计优化补偿机制。仿真结果表明,考虑定时漂移后的补偿机制有效降低了定时偏差。

基于激光传感器的输电线路塔杆倾斜监测系统设计

为了解决传统输电线路塔杆倾斜检测时无法实现实时监测的问题,设计了一种用于塔杆倾斜的实时监测系统。根据激光三角测量原理,设计了倾角传感器,建立了基于激光三角的塔杆倾测量模型,利用高斯拟合算法,计算出光斑移动的距离,再结合三角函数关系计算出塔杆的倾斜角度。构建了用于温度漂移误差补偿的广义回归神经网络(GRNN)模型,模型中采用了四重交叉验证来搜索GRNN最优的传播参数。实验结果表明,在补偿前,由温度漂移引起的激光三角倾角传感器平均测量误差为2.68°,使用GRNN对输出进行校正后,平均误差降低至0.51°,温度非线性为0.003%FS/℃。而整个系统的测量平均绝对误差达到了0.54°,降低了2.24°。

Robust Adaptive Control of Nonholonomic Systems with Nonlinear Parameterization

全球适应的州的反馈控制策略与强壮的非线性的飘移和未知非线性的参数在锁住的形式为 nonholonomic 系统的一个类被介绍。一种参数分离技术被介绍把非线性的 parameterization nonholonomic 系统转变成一个象线性一样 parameterized nonholonomic 系统。然后，反馈支配设计被使用设计一个全球适应稳定控制器，切换的策略被开发消除 uncontrollability 的现象。建议控制器能保证那得到状态全球性集成到起源的所有系统，当另外的信号仍然保持围住时。模拟例子表明有效性和建议控制器的柔韧的特征。

A Systematic Approach for Designing Analytical Dynamics and Servo Control of Constrained Mechanical Systems

A systematic approach for designing analytical dynamics and servo control of constrained mechanical systems is proposed. Fundamental equation of constrained mechanical systems is first obtained according to Udwadia-Kalaba approach which is applicable to holonomic and nonholonomic constrained systems no matter whether they satisfy the D'Alember's principle. The performance specifications are modeled as servo constraints. Constraint-following servo control is used to realize the servo constraints. For this inverse dynamics control problem, the determination of control inputs is based on the Moore-Penrose generalized inverse to complete the specified motion. Secondorder constraints are used in the dynamics and servo control. Constraint violation suppression methods can be adopted to eliminate constraint drift in the numerical simulation. Furthermore, this proposed approach is applicable to not only fully actuated but also underactuated and redundantly actuated mechanical systems. Two-mass spring system and coordinated robot system are presented as examples for illustration. © 2014 Chinese Association of Automation.

Controllable laning phase for oppositely driven disk systems

A two-dimensional binary driven disk system embedded by impermeable tilted plates is investigated through nonequilibrium computer simulations. It is well known that a binary disk system in which two particle species are driven in opposite directions exhibits jammed, phase separated, disordered, and laning states. The presence of tilted plates can not only advance the formation of laning phase, but also effectively stabilize laning phase by suppressing massively drifting behavior perpendicular to the driving force. The lane width distribution can be controlled easily by the interplate distance. The collective behavior of driven particles in laning phase is guided by the funnel-shaped confinements constituted by the neighboring tilted plates. Our results provide the important clues for investigating the mechanism of laning formation in driven system.

Numerical Simulation of Turret Moored Ship Performance in Variable Ice Drift Based on Heading Control

The frequent change in ice drift direction poses a significant challenge for turret moored ship in ice. Variability in ice drift is mainly caused by the winds and currents. To solve this problem, a new method with numerical simulation based on heading control is applied to reduce the risk of operation of The Arctic Tandem Offloading Terminal(ATOT),which includes an offloading icebreaker(OIB) moored to a submerged turret and a shuttle tanker moored at the stern of the OIB in this paper. An icebreaking tanker, MT Uikku, was modeled in a simulation program. Then the level ice load on the tanker was calculated with different ice thicknesses and drift speeds, after which a heading controller assisted with mooring system is used to simulate the horizontal motion of the tanker under the ice action.

Comparison of Wind-Induced Displacement Characteristics of Buildings with Different Lateral Load Resisting Systems

Due to excessive displacements of tall buildings occasioned by lateral loads, lateral load resisting systems are usually provided to curtail the load effect. The resistance may be offered by Frame Action, Shear Walls, or combined Walls and Frames (also known as Dual System). In this study, finite element based software, ETABS, was used to generate and analyse three-dimensional building models for the assessment of the relative effectiveness of the various lateral load resisting systems. Three models were used, one each for the three resisting systems. Each model consisted of three samples representing three different building heights of 45 m, 75 m, and 99 m. Wind Design Spreadsheet complying with the appropriate British Standards was used to compute preliminary wind load coefficients using the wind speed values from the relevant wind isopleth map of Nigeria as primary data. Lateral wind load was then applied at floor levels of each of the building samples. Each building sample was subjected to three-dimensional analysis for the determination of both the lateral displacements of storey tops and interstorey drifts. The results of the work showed that the dual system was the most efficient lateral-load resisting system based on deflection criterion, as they yielded the least values for lateral displacements and inter-storey drifts. The moment frame was the least stiff of the resisting systems, yielding the highest values of both the lateral displacement and the inter-storey drift.

Analysis on Motion and Cable Dynamic Tension for An ALT-Tanker System

A two-degree freedom model for an ALT-tanker system is established corresponding to the pitch of the ALT and the surge of the tanker.Tension in the mooring cable between the ALT and the tanker is represented by an unsymmetrical,piecewise-nonlinear function.Wave load on the tower is evaluated by use of the Morison equation.The first order wave load acting on the tanker is calculated by the linear diffraction theory based on the 2-D Helmholtz equation,and the near field approach of Pinkster is used to evaluate the second order drift force.The dynamic equation of motion is established based on the principle of D＇lembert.Dynamic response and cable tension of a mooring system composed of an 88.4 m ALT and a 100000 t grade tanker are calculated.The influence of wave frequency,wave excitation amplitude,wind and current force on ALT-tanker motion and cable tension is discussed.

Simulation design of fuze warhead system of air defense missile at very low altitude

A novel simulation method for fuze warhead system (FWS) at very low altitude flight is proposed to solve adaptability issues of the traditional one in the naval battle. Firstly, a simulation system framework is presented. Then the detailed implementation of a novel general fuze model, a novel sea echo model and a novel warhead dynamic effectiveness power field algorithm including the simulation system are presented. Finally, simulation results show good performance of the proposed method. The proposed method can simulate the echo signal when the complex fuze antennas detect target and the sea at the same time, and can truly reflect the target positions hit by the warhead fragments. The proposed method can solve the existing problems in the FWS simulation system.

一种基于SIC DSRD脉冲功率系统的优化方法

从脉冲功率系统优化的角度,提出了漂移阶跃恢复二极管(drift step recovery diodes, DSRD)器件的最优面积选取方法,建立了单开关DSRD驱动电路的线性拟合解析模型;结合SiC材料短空穴寿命的特性,提出了SiC基DSRD驱动电路参数的优化方案;基于该方案研制了采用SiC DSRD的脉冲功率源。实验结果表明,匹配负载为50Ω时,研制的脉冲功率源能输出760 V的峰值电压,脉冲上升沿达810 ps,且不存在单脉冲下的多次触发现象。该脉冲功率源输出脉冲前沿在亚纳秒量级,且波形稳定性好,脉冲源体积小,能应用于小型化超宽带电磁脉冲发生器。

福利错位:我国县域普惠养老政策的实践偏差及其解释

普惠养老服务体系的建设是我国当前养老服务体系发展的重要任务之一。在普惠养老的政策实践中,出现国家不断增加公共资源投入而老年人的福利状态并未同步改善的悖论。福利错位是理解这一制度悖论的关键。福利错位表现为福利覆盖范围上的城乡失衡与福利提供标准上的高位供给,其产生源于政府和市场作为福利供给主体的双重失灵。一方面,县域政府“福利政绩”导向使其在政策实践中侧重于福利效果的量化与福利实践的项目化;另一方面,市场主体为寻求政策补贴与地方政府形成了“依附式合作”的关系。普惠养老的关键在于对地方实际情况、对老年人养老需求的定位,要不断加强养老服务供给与老年人需求的衔接,促进养老服务体系的有效建设与均衡发展。

基于ZYNQ的磁悬浮天平测量系统设计与实现

针对磁悬浮天平系统存在设计结构复杂,造价昂贵的局限性同时测量数据漂移,长期测量的精度波动以及依赖于PC端来处理数据的问题,提出了基于ZYNQ的磁悬浮天平测量系统设计,设计运动控制器保证天平高精度定位的稳定性以减小天平托盘位置变化对驱动电流测量的影响,同时设计的小型ZYNQ系统完成AD、DA接口传输数据并在soc中完成数据的处理,回避了传统测量系统依赖PC端处理数据且受到PC端供电电源波动噪声而对测量精度产生的影响等缺点,以及通过修正算法抑制长时间测量所可能产生的数据漂移。实验结果表明:基于ZYNQ的磁浮天平测量系统优化了设计结构且造价低的同时保证了磁悬浮天平测量精度,有效抑制长时间测量带来的噪声和漂移。

机械陀螺漂移量检测系统设计

机械陀螺检测中漂移量是最主要的被测参数,其直接反映陀螺综合性能的优劣。为了实现对陀螺漂移量自动化、高精度的测量,建立陀螺漂移量检测系统。首先,运用光学知识分析光束的路径并建立多次反射式增程光路数学模型。其次,建立图像处理检测系统,对陀螺反射光斑进行识别处理,其主要工作为光斑跟踪和光斑中心定位。最后通过实验并根据实验结果调整检测系统。实验结果表明,在最佳检测条件下,机械陀螺漂移量的检测范围为±2°,其实验精度最高可达11″,符合陀螺漂移量检测稳定可靠、高精度的要求。