Impact of the equivalent center of mass separating from the sliding surface on the isolation performance of friction pendulum bearings

A new equivalent center of mass model of FPBs (friction pendulum bearings) is introduced, and based on this model, coefficient j of the equivalent center of mass separating from the sliding surface is defined. It is thought in theory that j has a significant impact on the isolation parameter of FPBs, since the equivalent post-yielding stiffness and friction coefficients are not simply determined by sliding radius and sliding friction pairs. The results of numerical simulation analysis using ABAQUS conducted on two groups of FPBs support this viewpoint. For FPBs with the same sliding radius and sliding friction pairs, the FPB modules of structural analysis software such as ETABS could only distinguish the equivalent transformation using j one by one. The seismic response data obtained in a base isolation calculation example of FPBs are very different, which reveals that j’s impact on the isolation effectiveness of FPBs cannot be ignored. The introduction of j will help improve the classical structural theory of FPBs and the weak points of structural analysis software based on this theory, which is important in achieving more accurate analyses in structural design.

The Contribution of the Gravitational Propagation Delay to Orbital and Center of Mass Motions

Recent measurements have shown that gravitational waves and thus the gravitational interaction propagate with the speed of light. The propagation delay of the gravitational interaction in orbiting systems couples the orbital and center of mass motions. This causes the orbits to spiral out and the center of mass to accelerate. It is one of a number of small effects modifying the Kepler orbits. The calculations show that the analytical describable expansion of the semimajor axis started at a time that is less than the age of the systems. This could be caused by a collision of a system component in the past. The effect of this propagation delay on the motion of the Earth Moon and the Brown Dwarf 569Bab binary star system is analyzed. These systems were chosen because a considerable amount of measured astronomical data is available. The calculated results are in excellent agreement with the measured data. In galaxies, too, the energy transfer from the orbit of the star cloud to the center of mass motion causes the galaxies to ac-celerate. If galaxies are considered to be molecules of the universe, then the acceleration of the galaxies will cause the molecular gas to heat and expand. Alternatively, the loss in orbital internal energy of the galaxies should be included in the mass and energy in the calculation of the expanding Universe.

基于复合纳米振子系统的光学质量传感

提出了一种基于金刚石氮-空位(NV)色心-悬臂梁复合纳米机械振子系统,该系统将金刚石NV色心镶嵌在悬臂梁底部,再通过悬臂梁振动形变产生的应力与金刚石NV色心中的自旋电子相互作用实现耦合;进而利用光学泵浦-探测技术研究了该系统的相干光学特性。首先,基于该复合系统的探测吸收谱,提出了一种测量纳米机械振子频率的全光学方案,在红边带的条件下,可通过观测吸收谱中两尖峰的分裂宽度从而确定自旋与纳米机械振子的耦合强度。其次,由于金刚石NV中心电子自旋具有较长的相干时间,因此进一步基于该复合系统提出了一种室温下全光学质量传感方案。

Novel Evaluation Method of Vehicle Suspension Performance Based on Concept of Wheel Turn Center

The current research of suspension performance evaluation is mixed in the evaluation of vehicle handling and ride comfort. However, it is lack of a direct and independent evaluation method for suspension performance. In this paper, a novel wheel turn center method is proposed to evaluate the suspension performance. This method is based on the concept and application of wheel turn center （WTC） and sprung mass turn center （SPTC）. The vehicle body and each wheel are regarded to be independent rigid bodies and have their own turn centers which reflect respective steering motions and responses. Since the suspension is the link between vehicle body and wheels, the consistence between the sprung mass turn center and the wheel turn center reflects the effect and performance of the suspension system. Firstly, the concept and appropriate calculation method of WTC and SPTC are developed. Then the degree of inconsistence between WTC and SPTC and the time that they achieve consistence, when the vehicle experiences from transient steering to steady steering state, are proposed to evaluate suspension performance. The suspension evaluation tests are conducted under different vehicle velocities and lateral accelerations by using CarSim software. The simulation results show that the inconsistence of steering motion between vehicle body and wheels are mainly at high speeds and low lateral accelerations. Finally, based on the proposed evaluation indexes, the influences of different suspension characteristic parameters on suspension performance and their matches to improve steering coordination are discussed. The proposed wheel turn center method provides a guidance and potential application for suspension evaluation and optimization.

Interaction between an Accelerated Mass in Straight Motion and a Hidden Energy Reservoir as a Strict Mathematical Consequence of Special Relativity

A. Einstein and H.A. Lorentz had found that the mass of an accelerated body traveling at relativistic velocity appears to depend on whether the acceleration is performed in the direction of motion or in a transverse direction. E.P. Epstein rejected this result in the “Annalen der Physik”;he rather postulated an additional force that turns up when the body is accelerated in the longitudinal direction. It can be shown that the concept of an increased longitudinal mass is based on a simple mathematical error. When correcting this error, it turns out that Epstein’s additional, hidden force is indispensable in order to avoid an inner inconsistency of Special Relativity. It does most of the total work absorbed by the moving object, and is thus responsible for most of the increase in its energy (=mass), given the speed attained is relativistic. In other words: While the total force on the body needed to maintain a constant acceleration a0 is “(1-v2/c2)-1ma0=m0(1-v2/c2)-3/2a0”, the technical force needed to maintain that acceleration amounts only to “ma0=m0(1 - v2/c2)-1/2a0”. The total energy of two objects that undergo a symmetrical, elastic head-on collision is therefore not conserved during the collision, thus requiring the involvement of a hidden reservoir of energy. This result is confirmed by calculations that use the concept of momenergy. The phenomenon of an apparent disappearance of energy has been noticed in particle physics already (target-experiment), but its consequences have been ignored. Instead, an explanation has been given (reduced “energy of the center of mass”) which is inconsistent and violates the relativity principle.

论太阳轨道运动不绕过太阳系质心的准2400年周期成因

K指数越大表明行星系统在某一径向方向会合的程度越大.K指数极值标定的太阳轨道运动半径的变化具有凸显的准20 a、179 a、2400 a周期嵌套关系.随时间尺度的增大,K指数极大值不但呈现出显著的准2400 a周期,而且太阳系质心在太阳本体内外持续的时间长度的变化也具有准2400 a周期.这其中隐含太阳轨道运动不绕过太阳系质心的准2400 a周期特殊规律.本文以木星和太阳连线为基准方向,创建了行星会合向量指数K.K向量指数图像清晰地呈现出由13~14个准179 a包络线周期(其中3~4个周期谷值出现K<0)构成的太阳轨道运动不绕过太阳系质心的准2400a周期.这一发现为科学辨识太阳轨道运动特征的复杂性又向前推进一步.

基于动平衡的电机轴质量定心系统研究

提出基于动平衡理论的质量定心系统。以双面动平衡法测算电机轴不平衡量,以质量定心原理建立不平衡量与质心偏移量的关系,通过解算得到质心偏移量,数据通过TCP/IP网络通信发送给可编程逻辑控制器PLC控制加工中心去重加工。结果表明,电机轴经过质量定心系统去重后,剩余不平衡量达到0.04~0.06 g,与有质量定心机的质量定心系统相比,该系统成本更低,数据传输距离远,传输干扰小,数据更准确。

小推力空间发动机系统优化分析

基于空间发动机系统质量模型和质心漂移模型，进行了燃烧室压强及气瓶形状优化分析。研究结果表明：①燃烧室压强最佳值为１ＭＰａ，此时发动机系统质量最小；②采用环形气瓶具有优势，发动机系统质量较小，没有质心漂移。

自由偶极子运动规律研究

讨论了由正负离子实组成的自由偶极子的相互作用能,分析了仅在该作用下偶极子的运动,求解其运动方程,得出自由偶极子的运动为匀速直线运动和简谐振动的叠加,其质心作匀速直线运动,在质心系中,两离子分别在其平衡位置附近作简谐振动.

变质心执行机构对弹头命中精度的影响分析

弹头变质心机动控制是通过移动弹头的质心位置,利用气动配平力矩改变弹头的飞行姿态和攻角,从而可实现弹头机动控制。在给出变质心弹头的动力学方程的基础上,通过对该动力学方程进行简化和线性化,推导出变质心弹头关于攻角和侧滑角的传递函数,在加入舵机伺服系统后,分析变质心伺服系统的性能对弹头跟踪精度和弹道命中精度的影响,最终确定变质心执行机构的动态性能参数并为今后变质心执行机构的设计提供必要的参考。

多载体信息资源整合平台构建及关键技术应用

多媒体资源建设从无序化建设向有序化建设发展是高校资源建设的必然过程.在资源建设高度整合的今天,不仅需要体系架构合理、科学的硬件支撑平台,而且也需要集中管理的软件支撑平台.文章以深圳职业技术学院建设为例,着重讨论应用基于ALEPH500和MetaLib/SFX系统构建多载体资源中心的软硬件系统平台,实现软硬件平台共享与多媒体资源共建的解决方案.

太阳系质心参考系中日心运动规律的研究

在太阳系简化模型条件下,考虑太阳和5颗大行星的位置关系,在太阳系质心参考系中给出了多个不同时间段内日心的运动轨迹,初步得出了日心的运动规律.

质心参考系下弹性碰撞规律的形式与方法

研究了质心参考系下弹性碰撞过程,得出质心参考系下的碰撞公式.对"牛顿碰撞定律"及"状态方程"的初状态的解进行新的理解.最后对教法与学法归结了启示.

平面运动刚体系统中的达朗原理

将平面运动刚体系统中各刚体的惯性力系向各自质心简化，然后运用力的平移定理向刚体系统的总质心简化．推得系统的惯性力系主矢和主矩表达式，最后运用达朗伯原理来解此刚体系统的动力学问题并阐述了这一方法的特点和意义。

利用SLR反演地心运动

为获取地球质心运动,本文利用SLR卫星Lageos1及Lageos2反演了1阶球谐系数,并进一步计算了地球质心,获取了1993年-2006年地心运动时间序列。结果显示:1阶球谐系数C10、C11、S11量级为10-8;地心运动X方向振幅为25.5mm±3.2mm;Y方向变化在28.6mm±2.3mm;Z方向较大为35.0mm±4.3mm。

评“相对论的质心运动定理”

在相对论情况下,质点系统的质心是一个不确定的概念.在相对论力学中,质心系(质量中心参照系)亦被有确切定义的动量中心系(系统总动量为零的参照系)所代替.本文对《相对论的质心运动定理与质量亏损》一文的论证和结果作出了评论.

计算碰撞力的方法

在子结构离散的柔性多体系统的动力学基础上，由质点系统的质心运动定理建立了与接触碰撞有关约束的Ｌａｇｒａｎｇｅ乘子和撞击力的关系．计算了平面三连杆机构在撞击过程中撞击力的变化规律和一些特殊节点相对浮动坐标系的平移位移，以及太阳电池阵展开过程中各构件之间的撞击力．通过计算发现，撞击力经过一定时间达到峰值后逐渐下降．在撞击发生时参加碰撞的物体的动力学响应较大，但其他物体的动力学响应很小，由此可见，冲击波在柔性体中传播需要一定的时间．

全民健身中心多元化老年健身服务体系的构建

采用问卷调查和实地调研等方法调查我国北方吉林、辽宁、河北、山东、北京的16家全民健身中心场馆经营服务现状,发现全民健身中心场馆经营理念相对滞后、对老年人提供的健身服务项目单一、缺乏积极正确的健身指导、医务监督、人身保险等机制不够健全,与经常参加运动老年人的健身意识和保健防病的要求存在一定差距。据此,建议将社会医疗保险个人资金纳入公共场馆健身消费之中,提出了应进一步开发全民健身中心场馆的功能和建立完善的多元化老年健身服务体系。

车辆特性与ABS控制算法的适应性研究

针对车辆防抱死制动系统(ABS)控制算法的选择及适用问题,提出控制算法的选择应与车辆结构及实际性能要求相结合的方法,可以充分发挥不同ABS控制算法的优越性;使用Matlab/Simulink仿真软件建立车辆单轮制动模型,针对不同的初始制动车速和质心位置向后移动两种情况,分别采用变结构滑模控制和PID控制进行了制动过程的模拟与研究;仿真结果表明,当车辆结构及制动条件发生变化时,两种控制方式都能很好的完成制动,且各有优点,可以满足不同制动性能的需求。

基于大型物联网的物流货物追踪定位系统的设计与实现

提出一种基于大型物联网的物流货物定位系统,分析了该系统设计的硬件以及软件体系,通过加权质心定位算法中的加权因子体现不同传感节点同目标货物间的关联性,实现对突变环境下物流货物的准确定位,通过二维马尔科夫时空的应急控制模型,对滞留货物等非正常物流货物情况进行有效的监控。系统测试结果说明,该种基于物联网的物流货物定位系统能够对滞留货物量进行准确定位分析,并具有极高的定位效率、准确率和较低的定位误差,具有极高的应用价值。