Near resonance vibration isolation on a levered-dual response(LEDAR)Coulomb-damped system by differential preloads/offsets in linear springs

The levered-dual response(LEDAR)Coulomb-damped system attains near resonant vibration isolation by differential preloads/offsets in linear springs.It takes the advantages of both the preloads/offsets in linear springs and the guiderail friction for realizing different levels of vibration isolation.The isolation capacities are investigated on the strategies with both the horizontal and vertical guiderails,with the horizontal rail only,and without guiderails.The compressive preloads generally result in the consumption of most of the initial excitation energy so as to overcome the potential threshold.The isolation onsets at the frequency ratio of 1∓0.095 on the left-hand side(LHS)and the right-hand side(RHS)of the lever are relative to the load plate connector.The observed near resonant isolation thus makes the LEDAR system a candidate for the isolation of the mechanical systems about resonance while opening a path for simultaneous harvesterisolation functions and passive functions at extreme frequencies.

Design a Special Fixture for Tractor Lever

Aiming at the problems of long time and poor machining precision in processing the tractor lever workpiece,a special fixture suitable for the tractor lever workpiece is designed by analyzing the processing technology of the lever workpiece,and the workpiece is accurately positioned and tightened under the action of the special fixture.Efficient machining of the workpiece can be achieved by using a drill template.The fixture not only has the advantages of high production efficiency,low cost and high life,but also effectively improves the processing technology of the workpiece,and has certain reference value for the subsequent fixture improvement design.

ANALYSIS OF LEVER ARM EFFECTS IN GPS／IMU INTEGRATION SYSTEM

Disturbance specific force caused by the lever arm ef-fects in integration navigation system is investigated,Navigation errors eaused by the lever arm effects have been demonstrated under three flinght scenarios of the air-craft.Analytical under three flight scenarios of the ari-craft.Analytical results show that disturbance specific force resulted from lever arm effects may become one of the major error sources while an aircraft undertakes the maneuvers,and mavigation errors caused by the lever arm effects accumulate rapidly with time.Therefore,a com-pensation method must be taken into account to eliminate the disturbance specific force caused by the lever arm ef-fects in integration navigation system.

Hybrid Kalman and unscented Kalman filters for INS/GPS integrated system considering constant lever arm effect

In inertial navigation system(INS) and global positioning system(GPS) integrated system, GPS antennas are usually not located at the same location as the inertial measurement unit(IMU) of the INS, so the lever arm effect exists, which makes the observation equation highly nonlinear. The INS/GPS integration with constant lever arm effect is studied. The position relation of IMU and GPS's antenna is represented in the earth centered earth fixed frame, while the velocity relation of these two systems is represented in local horizontal frame. Due to the small integration time interval of INS, i.e. 0.1 s in this work, the nonlinearity in the INS error equation is trivial, so the linear INS error model is constructed and addressed by Kalman filter's prediction step. On the other hand, the high nonlinearity in the observation equation due to lever arm effect is addressed by unscented Kalman filter's update step to attain higher accuracy and better applicability. Simulation is designed and the performance of the hybrid filter is validated.

A new lever-type variable friction damper for freight bogies used in heavy haul railway

To overcome defects caused by the complex structure and unstable damping performance of the wedge- type damper, a new lever-type friction damper has been developed for use in freight bogies; the design allows the advantages of traditional three-piece bogies to be retained. A detailed description of the structure and mechanism of the lever-type damper is provided, followed by a stress analysis using the finite element method. Dynamic per- formance characteristics of the lever-type damper and the wedge-type damper are compared in terms of the nonlinear critical speed, riding index, and curve negotiation. The results indicate that the maximum stress of the lever remains below its yield limit. The lever-type car has higher running performance reliability, and achieves similar nonlinear critical speed, riding index, and curve negotiation when compared with the wedge-type car.

Executive Stock Option, Mediation of Agency Costs and Allocation of Power in Levered Firms

The relationship between options and agency costs in levered firms is studied by modeling the effect of executive stock options on the manager's investment strategy in levered firms. Stock options do not necessarily aggravate agency costs in levered firms. The corporate governance affects agency costs greatly. If debt-holders were entitled to design executive stock options together with stockholders, by allocating power properly between stockholders and debt-holders, firm value could be enhanced greatly. The following way of allocating power between the two parties is proposed: the exercise price should be the weighted average of the stockholders' and debt-holders' suggested exercise prices. The weight allocated to debt-holders is positively related to the amount of debts that debt-holders lend to stockholders.

Morphological differences of hindlimb levers between wild and farmed American mink(Neovison vison)and implications for reintroduction of mustelids

Reintroduction is an important strategy to restore or re-establish wild populations of endangered species.Pre-release training is a necessary step to ensure postreintroduction survival.However,studies reported contradicting outcomes after pre-release training of juveniles and adults.This study used farmed and feral American mink(Neovison vison)to analyze the influence of captive breeding on the morphology,structure and efficiency of the two major hindlimb levers,the femur and tibia pivoted by hip and knee joints that are essential for locomotion.Results showed that captive breeding did not alter the sexual dimorphism of the two levers that are related to survival in the wild.Captive-bred mink showed slightly altered morphology of the femur and fundamental structure of the hindlimb levers that improved efficiency,but this resulted in reduction of performance related to foraging in both terrestrial and aquatic environments,especially for females.These findings suggest that reintroduction of mustelid as exampled by the mink here should focus on juveniles because the skeletal alterations associated with captive rearing were recorded only among adults and are irreversible in adulthood.In contrast,captive-reared juveniles showed no skeletal alterations and would be expected to recovery from any atrophy of the muscular system caused by captive rearing for shorter durations.Our results support the application of pre-release training of juveniles in enriched environments as a method for alleviating structural alteration of appendages and enhancing locomotion to increase survival probability in complex habitats.

Modeling and analysis of magnetic spring enhanced lever-type electromagnetic energy harvesters

This study presents a novel enhanced monostable lever-type electromagnetic energy harvester(L-EEH).According to the positions of the coil and the lever pivot,four configurations are discussed to realize a better harvesting performance of the L-EEHs.On the basis of establishing the theoretical model of the L-EEH,the corresponding analytical solutions can be obtained by applying the harmonic balance method.The effects of the nonlinear coefficient,the lever ratio,the mass ratio,and the circuit parameters on the energy harvesting performance of L-EEHs are analyzed and discussed.The numerical and experimental efforts are carried out to verify the theoretical model and the energy harvesting performance.The results demonstrate that the maximum output voltage can be achieved with an appropriate lever ratio.Furthermore,the L-EEH possesses a considerable energy harvesting performance under a smaller lever ratio compared with the other three configurations.The output power can also be improved by adjusting the tip mass of the lever.The proposed L-EEH has a considerable operating bandwidth and an output power,which can reach 146.6 mW under the excitation amplitude of 0.3 g.

Lever-Loading System Analysis and Application

In order to prove the rationality of structural design and carrying capacity, reasonable design of lever-loading system to apply loadings to some loading-points was needed in spacecraft structural mechanics static test. Lever-loading system design affects the carrying capacity of test piece. This paper describes the application of different section loading beams. Optimizing and analysis the different models of loading beams, and verification the feasibility of combination beams.

Development of Verification Device for Starting Lever Pressing Automation of DEM6 Portable Three-cup Anemometer

At present,the verification system of wind speed in national 3MS provincial automatic weather station has been automated,but the wind speed verification of the DEM6 portable three-cup anemometer by the straight road wind tunnel cannot be automated.In order to record the reading of this verification,it is necessary to manually move the starting lever at the wind speed field during each verification.For this problem,a set of verification device for the DEM6 portable three-cup anemometer is developed based on automatic verification system of wind speed in the 3MS provincial automatic weather station.This device uses the the driving board of starting anemometer to connect with the pressing starting lever by a bar-shaped gap,so as to realize the remote control of the starting lever.It is convenient to use,and measure multiple sets of data at the same place.The measuring results are more accurate,thereby realizing automatic pressing of wind speed starting lever.

Three-dimensional atomic force microscopy based on tailored cantilever probe with flared tip

In order to meet the requirements of nondestructive testing of true 3D topography of micro-nano structures,a novel three-dimensional atomic force microscope(3D-AFM)based on flared tip is developed.A high-precision scanning platform is designed to achieve fast servo through moving probe and sample simultaneously,and several combined nanopositioning stages are used to guarantee linearity and orthogonality of displacement.To eliminate the signal deviation caused by AFM-head movement,a traceable optical lever system is designed for cantilever deformation detection.In addition,a method of tailoring the cantilever of commercial probe with flared tip is proposed to reduce the lateral force applied on the tip in measurement.The tailored probe is mounted on the 3D-AFM,and 3D imaging experiments are conducted on different samples by use of adaptive-angle scanning strategy.The results show the roob-mean-square value of the vertical displacement noise(RMS)of the prototype is less than 0.1 nm and the high/width measurement repeatability(peak-to-peak)is less than 2.5 nm.

Optimizing Social Impact in Organizations:Concepts,Levers and Barriers

With the socio-economic change that has taken place over the last years,in addition to an increase in sustainability regulation,stakeholders have gained importance and organizations are more active in relation to generating social impact,but society demands more and better social impact from organizations.The objectives of this paper are to clarify the concepts of impact and social impact optimization,and to detect levers and barriers to help organizations optimize the social impact that they generate.A qualitative approach based on interviews with social impact leaders from organizations with different forms(big companies,small and medium-sized enterprises,corporate foundations,b-corps,community foundations,public and private foundations,associations and investing firms)is applied,together with focus groups with stakeholders from those organizations that are best practices.

魅摄人物 Martin Levers

商业保险经纪人,工作之余还需兼顾家庭,但Martin仍挤出时间创作出大量优美的风光摄影作品。

China Engages Monetary Levers

Driven by a steady increase in both food and non-food prices, the expected growth of consumer price index （CPI） for September was 2.5 percent year on year. This is a gain on the August level of 2.3 percent year on year. Upward pressures on price leading up to the Chinese National Day holiday in early October and rising crude oil prices globally also contributed to an upward adjustment in prices.

平行级联光杠杆测量金属丝杨氏模量

光杠杆能放大微小变化量,在原子力显微镜,精密天平和杨氏模量测量等领域都有重要的应用。级联光杠杆能够在有限空间内提高传统光杠杆的放大倍数而受到广泛关注,但仍存在不容易确定反射级次,入射光与光杠杆倾斜平面必须有一定初始夹角等问题。平行级联光杠杆通过在垂直于光杠杆倾斜面的平面放置多个光杠杆,形成多次反射提高放大倍数,每个镜面进行一次反射,易确定反射级次,并且入射光与光杠杆倾斜平面可无初始夹角。研究分析了平行级联光杠杆的光路及测量原理,确定了计算公式,并通过测量金属丝杨氏模量进行了实验验证。利用望远镜观测的方法,通过三级平行级联光杠杆,放大倍数可达103.7倍,与单个光杠杆相比,提高了一个数量级。

“一带一路”共建国家银行业系统性风险的测度研究

有效识别“一带一路”共建国家的系统性风险及其关键驱动因素对平稳实现各国经济金融的深度融合具有重大的现实意义。基于150多万条银行微观股票数据和财务数据,通过构建压力时期回归模型的客观方法获得系统性风险三因素权重,在同一框架下利用规模、杠杆、关联性3个因子测算了银行、国家、“一带一路”共建国家系统3个层次的银行业系统性风险指数。研究结果表明,从系统性风险表现来看,“一带一路”共建国家整体的银行业系统性风险受全球宏观金融环境波动影响显著。此外,“一带一路”共建国家也会因为自身问题而出现银行业系统性风险上升的情形。印度、越南、印度尼西亚等国家是系统重要性国家,其银行业系统性风险水平较高;匈牙利、克罗地亚、罗马尼亚等国家的银行业系统性风险水平较低。银行业系统性风险较高的国家主要在于其有较高系统性风险贡献水平的银行,且各行业经济发展状况以及经济增长对国家层面系统性风险有显著的影响。从风险驱动因素看,关联性因子是驱动银行业系统性风险水平变化的主要因素,其次为规模因子和杠杆因子。

位移放大型黏滞阻尼装置的减震效果研究

为解决普通黏滞阻尼器性能在层间位移较小的结构或位置难以得到充分发挥的问题,提出一种基于杠杆原理将位移和速度放大的黏滞阻尼装置,该装置通过放大普通黏滞阻尼器两端的相对位移,进而放大相对速度,使阻尼器性能得以充分发挥,更好地达到降低结构地震响应的效果。以某实际工程结构为背景,通过SAP2000有限元软件建立有限元模型,分析原结构、附加普通黏滞阻尼器结构和附加放大型黏滞阻尼器结构在3条地震波作用下的地震响应。结果表明,在3条地震波作用下,相较于附加普通筒式黏滞阻尼器结构,附加放大型黏滞阻尼器结构的层间位移角和基底剪力降低幅度均较大,说明放大型黏滞阻尼器相较于普通黏滞阻尼器有更好的减震效果。

基于机载SAR成像场景评估的惯导标定技术

针对机载惯导航向角度误差大引起的机载合成孔径雷达(SAR)成像指向偏差问题,提出了基于机载SAR成像场景评估的惯导标定技术。该技术通过SAR成像均匀场景高分辨结果的数据挖掘,结合雷达天线方向图有效完成指向误差提取;并在此基础上结合惯导杆臂模型与卡尔曼滤波处理,完成惯导安装角度误差精准估计与补偿,最终通过实测数据有效验证了惯导角度误差的标定技术在工程应用中取得了更优异的SAR图像质量。该方法能够减少惯导角度误差影响,获取更高的机载雷达SAR成像控制精度,具备更加广阔的应用场景。

利用光杠杆测透镜的曲率半径

基于光杠杆测量物体微小形变的思想,结合光杠杆与迈克耳孙干涉仪移动平台,搭建了测量透镜曲率半径的装置.利用光杠杆足尖位置和平凸透镜所在球面的几何关系,推导出曲率半径的测量公式,并测量了不同规格透镜的曲率半径.实验结果表明:使用该装置测量的曲率半径与利用牛顿环装置的测量值相近.

基于两个点集间参数估计的DVL标定方法

[目的]为了提高无人艇(USV)捷联惯性导航(SINS)与多普勒计程仪(DVL)组合导航的精度,需要对DVL误差进行精确标定。[方法]首先,对DVL的安装误差角、杆臂、比例因子进行误差建模,着重分析舰船中杆臂误差项对组合导航定位产生的影响;然后,提出一种基于两个点集间参数估计的DVL误差标定方法,即将SINS/GNSS导航参数与DVL输出参数视为两个点集,将标定问题转换为两个点集间差值的估计问题,再利用卡尔曼滤波器对两个点集间的误差参数进行估计;最后,利用基于奇异值分解(SVD)的可观测性分析,对不同运动条件下滤波器的可观测性定量分析,给出标定过程中载体的运动策略。[结果]数学仿真和海试试验结果表明,标定后的SINS/DVL算法全局相对精度可达到0.122%航程;在角机动时,杆臂会导致SINS/DVL定位突变;补偿杆臂后的定位误差更加平滑,且整体上具有更小的定位误差。[结论]所提方法可为包括杆臂在内的各项DVL误差标定提供可行的途径。