CAARC高层建筑标模动态测力研究

CAARC高层建筑标模的动态测力试验在南京航空航天大学 NH-2低速风洞中进行。在均匀流场中以及模拟大气边界层中分别测量了模型的动态气动力和力矩的平均值、均方根值、峰值。试验目的是为检测 NH-2风洞的大气层边界模拟技术 ,动态天平、测试仪器以及动态数据采集和处理系统。试验结果表明 ,CAARC标模的所有动态气动特性在 NH-2中的测量值与国外资料中报导的结果符合得较好。因此 ,NH-2风洞的大气边界层模拟技术 ,动态天平。

战术导弹折叠尾翼展开动态测力试验技术研究

以某战术导弹折叠尾翼为研究对象,采用动态测力天平和加速度传感器以及角度传感器作为测量元件,获得了折叠尾翼在快速展开过程中气动力的试验结果。还介绍了尾翼展开过程中气动力的处理方法,不同试验状态下对数据的特殊处理。对试验结果进行分析后表明,所采用的试验技术可行,试验数据可靠。

八维六自由度动态测力装置的研制及应用

针对直升机动力学试验中载荷难于准确测量且各分量间耦合大的难题,研制了一种新型结构的八维六自由度动态测力装置。介绍了八维六自由度动态测力装置的结构设计原理、测量算法、标定及在直升机动力学试验中的应用情况。

多通道测力仪动态信号反向滤波补偿方法

为了消除动态测力仪的结构动态特性对测试结果的干扰,采用反向滤波的方法对动态力测试信号进行修正。根据最小相位系统理论设计反向数字滤波器,由单输入单输出反向数字滤波器的设计原理,提出了多输入多输出反向数字滤波器的设计方法。根据测力系统激励力与测试值之间的频响函数矩阵,建立测力系统传递函数模型,并进行最小相位转化,将最小相位动态力传递函数模型反转,得到反向滤波器。实验结果表明:经过反向滤波处理的动态力测试值与实际动态力具有相同的幅值;运用零相位滤波方法,消除了测试信号与实际动态力之间的相位差;测试结果与动态力实际输入幅值误差小于6%。

动态称重测力技术的现状和发展趋势

本文从动态测量、自动在线测量、模型化测量和数字化测量等四个方面 ,阐述了称重测力技术的现状和发展趋势 ,简要介绍了动态称重测力的特征及研究方法 ,叙述了自动在线测量的必要性及常用的自动秤 ,指出了模型化、数字化测量的意义及开发软件技术的重要性。

动态称重测力技术的现状和发展动向

本文从动态测量、自动在线测量、模型化测量和数字化测量四个方面,阐述了称重测力技术的现状和发展动向。简要介绍了动态称重测力的特征及研究方法,叙述了自动在线测量的必要性及常见的自动秤,并指出模型化。

纺织电子式强力仪测力动态特性分析与人定方法研究

对纺织电子式强力仪测力部分动态性能的要求和影响电子式强力仪动态特性的因素进行分析，对其检定方法进行了研究和验证。

导弹高速动态空气动力特性

简介了导弹高速动态实验采用的设备和实验方法 ,研究了折合频率 ,平均迎角和空气压缩性对基本十字翼导弹纵向动态气动特性的影响。

提高变体飞机风洞测力试验精度的方法研究

变体飞机风洞试验主要测量机翼等变形过程对流场的扰动引起的动态气动力、力矩和力矩操纵效率变化。相对于常规测力试验,由于模型的变体运动导致试验数据精度差。本文对纯机械驱动的变体飞机模型的风洞试验精度的主要影响因素进行了分析,从试验方案、数据采集触发方式和数据处理方法等进行了改进。验证试验表明,试验精度大幅提高,升力系数重复性最大误差约为0.00538,阻力系数重复性最大误差约为0.00098,俯仰力矩系数重复性最大误差约为0.00113,动态试验精度达到常规试验水平。

1000kV双回路特高压输电塔顺风向等效静风荷载研究

基于高频动态天平测力试验,研究了1000kV双回路特高压输电塔的等效静力风荷载。基于准定常理论和不同高度的脉动风荷载无量纲自功率谱相等的假设,得到了塔身不同高度处的风荷载自谱和互谱。分别计算了输电塔风偏角为0°和90°时的等效背景风荷载、等效共振风荷载和总等效静风荷载,给出了不同高度处的阵风效应因子,可为特高压输电塔的风荷载计算提供依据。

超声键合过程中键合压力特性的实验研究

建立了超声键合压力的测量工作台,对工作台进行静态线性度标定和动态重复性测量,利用动态压电测力传感器对超声键合系统键合压力大小进行测量,得出不同压力作用下传感器力响应曲线图,分析其频谱图,发现保持某一固定功率(4.5格2.25W),可以找到合适的键合压力(5格0.719N)与其匹配。这些实验现象和结果可作为超声键合过程参数匹配及优化的依据。

Method of Testing of Dynamic Forces on Digital Jet Elements

Method of testing for dynamic output forces from jet elements is studied, the handwidth is large in testing with this method. By establishing a model of the test system and simulating it, principles of how inherent features of the test system affect the dynamic force test are found out. Thus a theoretical foundation is given for the design and error modification to the actual test system.

一种切削力信号分析系统的开发及应用试验

切削力的测量与分析对刀具状态的监控、加工质量的保证具有重要意义,并广泛地被现代机械制造企业所重视。文中首先简要说明了切削力信号分析系统的开发过程,包括硬件的组成及使用,分析系统软件的总体设计和各模块的构建。其次,利用所开发的切削力信号采集与分析系统自行设计了切削试验,并对实验结果进行了分析和处理。最后,将试验结果与切削力建模与仿真结果做了比对,验证了本信号采集与分析系统设计的合理性和使用的准确性,对实际生产中切削力的控制具有一定的指导意义。

Connections on Phase Space of AutonomousMechanical Systems with Constraints

The covariance of a dynamical flow with respect of a connection on tangent burdle is put forward The connection of an autonomous constrained mechanical system is found whose geodesic equations are equations of motion of the systems The connection is determined by dynamical functions and constraints of the system of the system and is reduced to the usual dynarmical connection of the dynamical flow is second drder homogmogeneous one.

Optimal arrangement for pressure measurement points in working chamber of earth pressure balance shield

In order to exactly provide scientific basis for pressure dynamic balance control of working chamber of earth pressure balance shield (EPBS),study on optimal arrangement of pressure measurement points in working chamber was conducted. Based on mathematical description of optimal arrangement for pressure measurement points,fuzzy clustering analysis and discriminant analysis were used to divide pressure regions of nodes on bulkhead. Finally,the selection method of optimal measurement points was proposed,and by selecting d6.28 m EPBS as study object,the case study was conducted. By contrast,based on optimal arrangement scheme of pressure measurement points,through adopting weighted algorithm,the absolute error mean of equivalent pressure of working chamber is the smallest. In addition,pressure curve of optimal arrangement points presents parabola,and it can show the state of pressure distribution on bulkhead truly. It is concluded that the optimal arrangement method of pressure measurement points in working chamber is effective and feasible,and the method can provide basis for realizing high precision pressure control of EPBS.

Online dynamic measurement of saturation-capillary pressure relation in sandy medium under water level fluctuation

An online dynamic method based on electrical conductivity probe, tensiometer and datataker was presented to measure saturation-capillary pressure （S-p） relation in water-light nonaqueous phase liquid （LNAPL） two-phase sandy medium under water level fluctuation. Three-electrode electrical conductivity probe （ECP） was used to measure water saturation. Hydrophobic tensiometer was obtained by spraying waterproof material to the ceramic cup of commercially available hydrophilic tensiometer. A couple of hydrophilic tensiometer and hydrophobic tensiometer were used to measure pore water pressure and pore LNAPL pressure of the sandy medium, respectively. All the signals from ECP and tensiometer were collected by a data taker connected with a computer. The results show that this method can finish the measurement of S-R relation of a complete drainage or imbibition process in less than 60 min. It is much more timesaving compared with 10-40 d of traditional methods. Two cycles of water level fluctuation were produced, and four saturation-capillary pressure relations including two stable residual LNAPL saturations of the sandy medium were obtained during in 350 h. The results show that this method has a good durable performance and feasibility in the porous medium with complicated multiphase flow. Although further studies are needed on the signal stability and accuracy drift of the ECP, this online dynamic method can be used successfully in the rapid characterization of a LNAPL migration in porous media.

Influence of substituting Ni with Co on hydriding and dehydriding kinetics of melt spun nanocrystalline and amorphous Mg_2Ni-type alloys

In order to improve the hydriding and dehydriding kinetics of the Mg2Ni-type alloys,Ni in the alloy is substituted by element Co. The nanocrystalline and amorphous Mg2Ni-type Mg2Ni1-xCox (x=0,0.1,0.2,0.3,0.4) alloys were synthesized by melt-spinning technique. The structures of the as-cast and spun alloys were studied with an X-ray diffractometer (XRD) and a high resolution transmission electronic microscope (HRTEM). An investigation on the thermal stability of the as-spun alloys was carried out with a differential scanning calorimeter (DSC). The hydrogen absorption and desorption kinetics of the alloys were measured with an automatically controlled Sieverts apparatus. The results demonstrate that the substitution of Co for Ni does not alter the major phase of Mg2Ni but results in the formation of secondary phase MgCo2. No amorphous phase is detected in the as-spun Co-free alloy,but a certain amount of amorphous phase is clearly found in the as-spun Co-containing alloys. The substitution of Co for Ni exerts a slight influence on the hydriding kinetics of the as-spun alloy. However,it dramatically enhances the dehydriding kinetics of the as-cast and spun alloys. As Co content (x) increases from 0 to 0.4,the hydrogen desorption capacity increases from 0.19% to 1.39% (mass fraction) in 20 min for the as-cast alloy,and from 0.89% to 2.18% (mass fraction) for the as-spun alloy (30 m/s).

门窗执手操作力的测量不确定度评定

门窗执手操作力测试装置是动态测试执手在开启和关闭过程中的操作力,要求测量器具的受力方向始终与执手手柄中心线的竖直平面保持垂直。针对门窗执手操作力测试装置的工作特点,从执手轴心与驱动臂轴心同轴、施力位置测量误差、传感器受力支点垂直度、测量重复性、力值误差等方面引入的不确定度进行了分析和探讨,可为同类五金产品操作力测量不确定度的评定提供参考。

Viscoelastic micromechanical model for dynamic modulus prediction of asphalt concrete with interface effects

A viscoelastic micromechanical model is presented to predict the dynamic modulus of asphalt concrete （AC） and investigate the effect of imperfect interface between asphalt mastic and aggregates on the overall viscoelastic characteristics of AC. The linear spring layer model is introduced to simulate the interface imperfection. Based on the effective medium theory, the viscoelastic micromechanical model is developed by two equivalence processes. The present prediction is compared with available experimental data to verify the developed framework. It is found that the proposed model has the capability to predict the dynamic modulus of AC. Interface effect on the dynamic modulus of AC is discussed using the developed model. It is shown that the interfacial bonding strength has a significant influence on the global mechanical performance of AC, and that continued improvement in surface fimctionalization is necessary to realize the full potential of aggregates reinforcement.

State Feedback Predictive Control for Hybrid System via Parametric Optimization

In this article, state feedback predictive controller for hybrid system via parametric programming is proposed. First, mixed logic dynamic （MLD） modeling mechanism for hybrid system is analyzed, which has a distinguished advantage to deal with the logic rules and constraints of a plant. Model predictive control algorithm with moving horizon state estimator （MHE） is presented. The estimator is adopted to estimate the current state of the plant with process disturbance and measurement noise, and the state estimated are utilized in the predictive controller for both regulation and tracking problems of the hybrid system based on MLD model. Off-line parametric programming is adopted and then on-line mixed integer programming problem can be treated as the parameter programming with estimated state as the parameters. A three tank system is used for computer simulation, results show that the proposed MHE based predictive control via parametric programming is effective for hybrid system with model/olant mismatch, and has a potential for the engineering applications.