电容式硅微加速度计变换方程的研究

研究了利用硅簿片为敏感元件的电容式加速度计，加速度计的悬臂梁与惯性质量块是一个整体结构，可以消除元件弹性连接的不完善性，而且极板间隙中空气相对介电常数εr的高稳定性是这种电容式传感器的优点之一。给出了敏感元件的实际弯曲函数，分析了其变换方程及非线性，研究表明，在设计电容式硅微加速度计时，只要间隙调制深度在-0.5- 0.5，加速度计的变换函数基本满足线性，得到的变换方程可以作为合理选择电容式加速度计的电极结构参数的理论依据。     

光电位置敏感探测器非线性误差校正方法研究

位置敏感探测器(PSD)以其分辨率高、时间响应性好的优点在光电检测领域得到了广泛的应用,但是PSD在生产过程中产生的非线性误差极大的影响了测量精度和范围,因此对PSD进行必要的非线性误差修正可以大大提高其测量精度和可靠性。     

基于MATLAB常微分方程仿真探索

介绍运用MATLAB对微分方程组的仿真方法。首先给出一阶、二阶的ode（ordinary differential equation）解，并利用SIMUUNK建立仿真模型，给出仿真结果图形；然后给出一个具体的应用实例。仿真算法具有模型设计简单、结果直观等特点有很强的使用价值。     

The application of an approximate analysis of the diffusion process for a description of creep and creep rupture

An analysis of the environmental effect on creep and creep rupture of metals is presented. It is pointed that the investigation of the diffusion processes leads to significant computational difficulties. These difficulties arise on representing the solution of the diffusion equation with variable boundaries in the form convenient for analysis.The process of damage accumulation is modelled for a material, which is subjected to the combined action of mechanical loads and the aggressive environment. The Rabotnov kinetic theory is applied in which two parameters are taken into account: the damage of the material and the concentration of chemical elements reducing the resistance of the material to mechanical loads. An approximate solution of the diffusion equation is suggested for rod or shell subjected to axial tension. This solution is based on dividing the cross-section of rod or shell into the disturbed and undisturbed parts and determining the motion of the boundary between these parts. The system of constitutive equations which describe the interaction between the diffusion and rupture fronts during the creep process until failure is obtained. A good quantitative agreement between experimental and theoretical results has been received.     

机床主轴径向误差运动在线检测与信号处理

在机床加工工件时,实时测量机床主轴的径向运动误差。测量对象是在该机床上加工的圆柱形工件,而不是通常所使用的标准棒。采用误差分离技术将工件的形状误差从所测信号中分离出来,实现在线测量主轴的径向误差运动。并采用基于自适应阈值的小波包算法去除加工时存在的噪声。同时,从谐波抑制特性和总体频域特性两个方面分析了测量系统频域特征。     

基于MSP430单片机的智能健康管理系统的设计

本设计是基于MSP430单片机的一款集心率、血压、体温测量于一体的简易健康设备.MSP430单片机通过对心率、血压、体温等数据的采集和处理,最终通过GSM模块将转换后的数据发送到特定的手机号码,通过收到的短信可以实时了解老人的身体状况.本设计的主控芯片选用低功耗的MSP430G2553,其处理能力强,运算速率快.本文简单介绍了此系统的原理与实现方式.     

Hop-by-hop Content Distribution with Network Coding in Multihop Wireless Networks

The predominant use of today's networks is content access and distribution. Network Coding (NC) is an innovative technique that has potential to improve the efficiency of multicast content distribution over multihop Wireless Mesh Networks (WMNs) by allowing intermediate Forwarding Nodes (FNs) to encode and then forward data packets. Practical protocols are needed to realize the benefits of the NC technique. However, the existing NC-based multicast protocols cannot accurately determine the minimum number of coded packets that a FN should send in order to ensure successful data delivery to the destinations, so that many redundant packets are injected into the network, leading to performance degradation. In this paper, we propose HopCaster, a novel reliable multicast protocol that incorporates network coding with hop-by-hop transport. HopCaster completely eliminates the need for estimating the number of coded packets to be transmitted by a FN, and avoids redundant packet transmissions. It also effectively addresses the challenges of heterogeneous multicast receivers. Moreover, a cross-layer multicast rate adaptation mechanism is proposed, which enables HopCaster to optimize multicast throughput by dynamically adjusting wireless transmission rate based on the changes in the receiver population and channel conditions during the course of multicasting a coded data chunk. Our evaluations show that HopCaster significantly outperforms the existing NC-based multicast protocols.     

油品馏程测定误差最小化的条件分析与参数控制

采用手动馏程测定仪测定重石脑油和轻柴油的馏程,从蒸馏速度、温度计的安装位置、水分含量、加热强度的控制、大气压、石棉垫孔径等几个方面分析影响实验数据准确性的因素,总结出馏程测定误差最小化的参数控制条件,保证分析结果的准确性。     

An improved accuracy-measuring method in manufacturing the lead screw of grating ruling engine

A measuring method was studied to further improve the manufacturing accuracy of the lead screw. Firstly, factors that can axially displace the screw shaft were analyzed and a relationship between factors and axial displacement was given. The axial displacement of the screw shaft was measured using a laser interferometer, and results show that the variation amplitude of the screw-shaft axial displacement was about 80 nm while the variation period was consistent with the rotation period of the screw shaft. Next, two methods of measuring the manufacturing accuracy of the lead screw were considered: a traditional method that measures the absolute position of the nut and an improved method that measures the displacement between the nut and screw shaft. A No. 4 screw shaft was manufactured under the guidance of results obtained using the improved measuring method. Experimental measurements were then made; results show that the pitch displacement errors obtained using the traditional and improved measuring methods were 0.6 and 0.4 μm, respectively, indicating that the improved measuring method is more exact. Finally, an echelle grating ruled by a grating ruling engine that used the No. 4 screw shaft as a macro-positioning element was introduced. Its excellent parameters indirectly show that the improved measuring method has better accuracy.     

Lateral performance evaluation of laser micromachining by high precision optical metrology and image analysis

Today several techniques are available for micro-manufacturing. Yet, it is difficult to assess the precision and lateral X,Y accuracy of these techniques. The available accuracy information is usually based on specifications given by machine suppliers. This information is based on in-house laboratory tests performed by dedicated machine operators and within an adapted environment. In practice, the accuracy is likely to vary due to environmental conditions, materials and operator skills. In order to check the specifications in realistic environments the EUMINAfab infrastructure consortium initiated a set of independent high precision onsite verification tests on different laser micromachining installations. In addition to providing performance verification, it gave the participating partners real capability information of their equipment and possibilities to improve machining performance to a higher level. In this study a comprehensive verification test was designed and carried out by using a high precision metrology method for 2D measurements based on subpixel resolution image analysis. This methodology improved our knowledge of the capabilities of three laser micromachining installations, and showed that specifications at single micron levels are hard to obtain.