侵彻混凝土的三维测试系统设计研究

现场试验时,由于弹体的初始偏航以及侵彻靶体面的倾斜,使得破坏过程和侵彻深度等参数与垂直侵彻有很大的区别。为了测试斜侵彻过程的参数,抗高冲击单轴加速度传感器已经不能满足测试要求。本文基于CPLD器件XCR3064为核心处理芯片;结#ADC、铁电存储控制器、电源管理模块,设计了三维加速度测试系统,不仅可以记录弹体发射、飞行时的加速度,还可测得着靶侵彻过程中各个轴向的加速度值。实测到的减加速度,为分析侵彻速度、侵深和数值模拟提供可靠,有价值的数据。     

一种新型三轴电容式加速度计的设计分析

设计了一种新型结构的体硅工艺梳齿电容式加速度计,该设计采用2个检测质量块,分别检测水平方向和垂直方向的加速度。x,y水平方向不对称梳齿的设计,消除了z轴对水平轴向加速度的干扰,同时z轴支撑梁的设计,解决了水平轴向对z轴的干扰。电容的差分结构有利于提高加速度计的检测性能。用Ansys仿真软件对敏感结构进行静态和模态分析,理论上验证了所提出的三轴电容式加速度计整体结构的可行性。     

新型抗振晶体振荡器的分析与设计

在车载和机载电子系统中,晶体振荡器在振动环境下的相位噪声性能发挥着重要作用。文中讨论了振动状态下晶体振荡器的相位噪声性能。采用双晶体谐振器设计了一种新型抗振晶体振荡器,从而实现了加速度灵敏度补偿。测试结果显示,加速度灵敏度补偿后的新型抗振晶体振荡器,在振动状态下的相位噪声可达-140 dBc/Hz＠1 kHz,性能得到20 dB以上的优化。因此,该方法在减小晶体振荡器的加速度、灵敏度方面均是可行且有效的。     

Effect of sheaths on the capacitance of a plane grid capacitor in a plasma

An experimental investigation of the capacitance of a grid capacitor shows that the minimum sheath occurs for the grids biased to space potential. Above space potential, the sheath is attributed to electron acceleration, and a simple calculation shows that this effect is of the right magnitude.     

Acceleration of series form of the Green's function for a magnetic line current in the presence of a conducting wedge

A scheme for accelerating the series form of the Green's function for a magnetic line current near a conducting wedge is considered. The acceleration technique employs a form of Kummer's transformation and is applied to two specific cases of interest. Data illustrating accelerated convergence are presented.<>     

Quazi-likelihood estimation of motion parameters of rapidly fluctuating target during the probing with a sequence of optical pulses

Characteristics of efficient estimates of the range, velocity, and acceleration of a rapidly fluctuating target have been obtained during the probing with a sequence of optical pulses. The losses in estimation accuracy of the range, velocity, and acceleration caused by the presence of non-informative parameters have been also found.     

一款视频解码芯片的硬件仿真加速

随着IC制造水平的提升和设计规模的增大,验证成为了IC设计的主要瓶颈之一.硬件加速器强大的仿真速度和查错能力使之成为大规模设计验证的优秀解决方案之一.根据视频解码芯片的需要,结合硬件加速器的特性,对视频解码芯片使用硬件加速器进行硬件仿真加速,取得高于40倍的加速效果.     

新型智能加速度传感器的设计

详细介绍了一种智能加速度传感器的具体实现方案.试验证明,该传感器性能稳定,具有测量精度高、价格较低、便携性好、灵活可靠的特点,克服了传统加速度传感器测量精度低,元器件精度要求较高,测试系统复杂昂贵,应用范围具有局限性的缺陷.它大大提高了加速度测量的自动化水平,具有重要的应用价值.     

An investigation of the pressure-to-acceleration responsivity ratioof fiber-optic mandrel hydrophones

The acceleration responsivity of the fiber-optic air-backed mandrel hydrophone is studied. This responsivity may be a significant noise source in high vibration environments. The pressure-to-acceleration responsivity ratio is therefore a figure of merit for the hydrophone. It is shown that an ideal hydrophone with a sufficiently rigid support cylinder should not show any first-order acceleration responsivity. The dominant contribution to any first-order acceleration responsivity is the deformation of the support cylinder due to acceleration. The responses are evaluated both theoretically and experimentally. This treatment gives a set of guidelines which should be followed in order to maximize the pressure-to-acceleration responsivity ratio. It is also theoretically and experimentally demonstrated that the axial acceleration responsivity can be significantly reduced by symmetrical elicitation of the hydrophone     

一种新型滑动杆式光纤光栅振动传感器研究

为了提高振动传感器对加速度信号测量的灵敏度 ,本文提出了一种新型的基于悬臂梁和滑动杆结 合的光纤光栅振动加速度传感器。详细阐述了传感器的结构和工作原理,并推导了传感器固 有频率和灵敏 度的理论公式。最后通过振动台测试了传感器的固有频率和灵敏度,并和光纤光栅仅沿光纤 轴向上受力的 实验数据进行了比较。实验结果表明,传感器频率响应曲线的平坦区域在10～38Hz之间,传感器的固有频 率为62Hz,灵敏度为52.8pm/g。与光纤光栅 仅沿光纤轴向受力的实验相比较,加速度灵敏度提高了70.8%。     

一种补偿加速度对目标回波影响的新方法

以雷达发射线性调频信号为例,分析了存在加速度条件下运动目标回波信号经过匹配滤波器后的失配问题,同时利用LFM回波信号的循环统计特性,提出一种基于循环相关变换的加速度估计算法,能够有效估计目标加速度参数,解决加速度带来的失配损失问题。利用Matlab进行仿真实验,验证了算法的有效性。     

Acceleration of heavy ions in a thruster

The acceleration of heavy ions in a Hall thruster is analyzed. The numerical solutions to the 1D hydrodynamic equations that describe the three-component system (neutral particles, electrons, and ions) are obtained. The conditions for the collisionless motion of ions, ion acceleration in the presence of the self-consistent electric field, and electron diffusion across the magnetic field are considered. The self-consistent field is calculated using the Poisson equation. The absence of singularity in the case when the ion velocity coincides with the velocity of ion sound is demonstrated. The critical magnetic field above which the propagation of ion beam is impossible is determined.     

Design and Implementation of a Mechatronic, All-Accelerometer Inertial Measurement Unit

This paper discusses the design, calibration, simulation, and experimental validation of a kinematically redundant inertial measurement unit that is based solely on accelerometers. The sensor unit comprises 12 accelerometers, two on each face of a cube. The location and direction of the sensors are determined so as to locally optimize the numerical conditioning of the system of governing kinematic equations. The orientational installation error of each sensor is identified by off-line iterative processing of the gravitational acceleration measurements made at a number of known orientations of the unit, thus allowing subsequent calibration. Furthermore, a novel procedure is developed through which the acceleration measurements can be used to directly determine the body angular velocity; this results in a major accuracy improvement over similar works whereby the angular velocity is obtained via integrating the angular acceleration. Experimental results are presented to validate the methodology, design, and implementation.     

Determination of the parameters of a 2-phase drag-cup accelerometer

A direct and reasonably accurate method of obtaining an electrical signal proportional to the angular acceleration is of immense interest in the design of feedback control systems. The 2-phase drag-cup motor is widely used as an angular accelerometer. In this letter we propose a new method of determining the electrical parameters of a 2-phase drag-cup accelerometer and show that our method is superior to an earlier method.     

基于复合控制的某型雷达伺服系统优化

针对传统的雷达伺服系统精度受动态设计中系统自身因素的制约而达不到期望特性的情况,提出了一种高阶无静差系统的实现,即把复合控制引入位置回路,前馈至速度回路输入端。将此种方案应用于某型雷达伺服系统,仿真实验表明在不影响系统稳定性的前提下,可使系统的幅频特性在低频段表现出极低的斜度,加速度常数增大,加速度误差减小,系统精度显著提高。     

空间微型光学载荷主结构优化设计与试验

针对某微型光学载荷主结构质量过重,地面重力变形过大以及基频太低的问题,提出以质量最小、随机加速度响应RMS值为目标,基频、变形为约束条件,建立优化数学模型,并对光学载荷主结构进行拓扑优化设计。对优化后的主结构进行工程分析,结果表明,优化后主结构质量为12.5 kg,降低了68.71%;基频由优化前的11.18 Hz提高到268.7 Hz;最大变形为0.3 m;光学载荷安装位置随机加速度响应值放大倍率1.2,小于总体指标1.5;最后对主结构和其上端安装的光学载荷进行了力学试验、热循环试验,并对试验后的设备进行了性能检测,结果满足总体指标,证明了所设计的主结构具有良好的性能,同时该主结构优化方法有效可行。     

Cardiovascular responses to acceleration stress: a computersimulation

Engineering methodology was used to develop a mathematical model of the cardiovascular system which is capable of predicting the effects of acceleration stress on peripheral and central vision. The basic model, previously reported, has been extended to include a simulation of the venous system and a number of additional refinements. It includes simulations of the heart, arterial, and venous system, physiologic compensatory mechanisms, and the effects of protective devices and maneuvers. Information derived from the model is important to understanding of cardiovascular responses to acceleration stress, mechanisms which determine tolerance, and factors which limit a pilot's performance. The model has been used to study the relative effectiveness of several acceleration protection methods and devices, including an anti-G suit design. Results from simulations using the model correlate well with reports in the literature     

Robust design of independent joint controllers with experimentationon a high-speed parallel robot

A linear independent joint control scheme is proposed. The design is made robust by closing another feedback loop that uses acceleration information besides the typical position and velocity loops. Reconstruction of acceleration measurements is performed via a suitable state-variable filter. Linear feedforward compensation is used to improve tracking performance of the closed-loop scheme. The control algorithm is tested first in a discrete-time simulation on a single-joint drive system with imposed disturbance torques. Then, real-time implementation on a high-speed parallel robot is presented. The experimental results demonstrate the effectiveness of the proposed technique     

一种面向ZynqNet硬件加速器的缓存优化结构设计北大核心

卷积神经网络ZynqNet广泛应用于边缘设备，但是现有FPGA硬件加速方案的帧率都小于30 FPS,较难满足实时性要求强的场景。文章聚焦于ZynqNet的FPGA加速性能提升，设计了基于多特征块并行计算结构，优化对Expand层的支持，增强了特征的复用，优化输出缓存，并可有效减少访存次数；设计了深度优先的特征和权重缓存机制，采用多Bank的缓存方式，仅需一个周期就能完成特征和权重的读取。基于Xilinx Xc7z045 FPGA芯片，完成了加速器硬件实现与性能测试，工作频率为166 MHz,计算性能为49 FPS,相比传统将整个网络部署到FPGA的方案，计算性能实现3倍加速，能效比提高了5倍。     

Acceleration of a gain-clamped semiconductor optical amplifier by the optical speed-up at transparency scheme

The optical speed-up at transparency principle has been successfully applied to a gain-clamped semiconductor optical amplifier yielding a remarkable acceleration in the gain recovery of the device as well as to the disappearance of the typical relaxation oscillations stemming from the coupling between the internal lasing mode and the carrier density. A record gain recovery time of 13 ps has been measured with an available gain of still 16 dB. A small-signal analysis of the semiconductor laser amplifier rate equations properly reproduces the acceleration of the recovery time and the disappearance of the relaxation oscillations. These results apply to semiconductor lasers in general.