基于低分辨率磁滞变化曲线的杆件拉力测量

根据磁弹基本原理可知,不同拉力作用下杆件材料的磁滞回线存在差异,据此提出了一种磁弹拉力测量改进方法。该方法先采用双套筒线圈式磁弹传感器采集不同拉力下杆件磁滞回线信号,并利用磁滞变化曲线衡量力对磁滞回线上每一点的影响,应用小波分析对磁滞变化曲线降维得到不同拉力下的低分辨率磁滞变化曲线特征,输入到神经网络进行训练,从而获得低分辨率磁滞变化曲线与拉力的映射关系。通过实验分析表明,磁滞变化曲线可以从本质上直观地反映拉力对磁滞回线上每一个点的影响。低分辨率磁滞变化曲线特征不仅包含着完整的拉力对磁滞回线每一点影响的信息而且特征维数低。应用基于低分辨率磁滞变化曲线和神经网络的拉力测量方法,无需分析灵敏度曲线和拟合确定系数曲线就可确定反映拉力的特征,可以实现多特征对拉力的拟合。接着,比较了误差反向传播神经网络(BPNN)、径向基神经网络(RBFNN)和利用线性插值样本训练的RBF神经网络对拉力的预测性能,发现利用线性插值样本训练后的RBF神经网络的预测效果,优于BP神经网络和没采用线性插值样本训练的RBF神经网络。最后,将基于低分辨率磁滞变化曲线和采用线性插值样本训练的RBF神经网络的拉力测量方法集成于双套筒线圈式杆件拉力测量装置并应用于实际拉力测量中,其拉力测量误差和确定系数分别达到0.11%和1,达到了实际测量要求,证明了该方法的有效性和可用性。     

Charge controlled delay element enabled widely linear power efficient MPCG-MDLL in 1.2V, 65nm CMOS

In this work, a robust, low-power, widely linear multiphase clock generation and multiplying delay-locked loop (MPCG-MDLL) architecture is realized, using a new differential charge-mode delay element circuit topology. The heart of any MPCG-MDLL architecture is the delay element, and hence, the characteristics of the delay element influence the overall performance of the MPCG-MDLL, in terms of its specifications such as peak-to-peak jitter, lock range, delay range, control voltage range, and power consumption. The proposed eight-phase MPCG-MDLL along with the charge-mode delay element outperforms the conventional MPCG-MDLLs that deploy delay elements such as a current-starved inverter (CSI), wide-range CSI, triply controlled delay cell, digital-controlled delay element, and the like. The eight-phase MPCG-MDLL along with the new charge-mode delay element circuit topology is implemented in 1.2-V, 65-nm CMOS technology. The performance results show that the eight-stage delay line has a delay range from 640 to 960 ps over the rail-to-rail control voltage range. The implemented MPCG-DLL is robust over process, voltage, and temperature (PVT) corners and exhibits a lock range of 400 MHz and a peak-to-peak jitter of less than 60 fs for all the DLL output phases and peak-to-peak jitter of 0.54 and 1.24 ps for the synthesized 5-GHz clocks for an input reference clock frequency of 1.25 GHz. The MPCG-MDLL consumes 4.74 mW of power and occupies an area of 0.017 mm².     

FIR digital filter-based ZCDPLL for carrier recovery

The objective of this work is to analyse the performance of the newly proposed two-tap FIR digital filter-based first-order zero-crossing digital phase-locked loop (ZCDPLL) in the absence or presence of additive white Gaussian noise (AWGN). The introduction of the two-tap FIR digital filter widens the lock range of a ZCDPLL and improves the loop’s operation in the presence of AWGN. The FIR digital filter tap coefficients affect the loop convergence behaviour and appropriate selection of those gains should be taken into consideration. The new proposed loop has wider locking range and faster acquisition time and reduces the phase error variations in the presence of noise.     

快速成形中STL格式文件的分割及其连续成形

为了避免巨型ＳＴＬ格式文件的读入错误和手工粘接带来的误差,研究了沿垂直于Ｚ向将巨型ＳＴＬ格式文件分割成多个ＳＴＬ格式文件,连续依次成形的方法,提出了分割面切割的轮廓环分解为三角形的算法。     

Effect of magnetic layer thickness on magnetic properties of Ce-Fe-B thin films

The Ce_2 Fe_(14)B thin films with a notable out-of-plane c-axis texture were prepared by DC magnetron sputtering on a Ta buffer layer. The morphological and magnetic properties were investigated. The thickness of the magnetic layer had a dramatic effect on the formation of Ce_2 Fe_(14)B phase,and excellent magnetic properties(H_(ci)≈4.25 kOe, M_r/M_s≈0.81) were observed for the Ce-Fe-B film with the thickness d_m = 200 nm. The results of the hysteresis loops for Ce-Fe-B film(d_m = 200 nm) at various measured temperatures show that a decoupling between the hard and the soft phases is observed at low temperatures, which is due to the regions with quite low anisotropy provided by the a-Fe. Moreover. it is clear that significantly various magnetization behaviors between the films with d_m = 200 and 300 nm were observed with a similar trend due to the existence of the a-Fe soft phase.     

(1-x)Pb(Ni1/3 Nb2/3)O3-xPbTiO3陶瓷的合成及其电滞回线

采用两步法在850℃合成了(1-x)Pb(Ni1／3Nb2／3)O3-xPbTiO3(x=0．28～0．42)陶瓷,粉末均为单一钙钛矿相。扫描电子显微镜观察和介电性能检测表明：所研究的陶瓷的最佳烧结温度为1200℃。对1200C烧结的0．64Pb(Ni1/3Nb2/3)O3-0．36PbTiO3陶瓷的铁电性能进行了详细地研究,发现组成在准同型相界的陶瓷铁电性得到增强．而这种铁电性增强正是由组分及结构和准同型相界的本质共同决定的。     

The Future of Information Modelling and the End of Theory: Less is Limited,More is Different

The computational design strategist Cynthia Ottchen , who was previously Head of Research and Innovation at OMA, offers insights into the future of building information modelling (BIM). Now in the Petabyte Age of the data deluge, she argues that in our adoption of BIM we have to surpass mere data collection and technical optimisation and open up new ways of thinking with the creative use of ‘soft data’. Copyright © 2009 John Wiley & Sons, Ltd.     

压电材料中缺陷偶极子特性的研究进展

压电材料通过受主掺杂或烧结挥发等可以形成缺陷偶极子, 缺陷偶极子对材料的性能有显著的影响。本文综述了压电材料中缺陷偶极子的产生及其在外场下的响应机理, 同时, 从缺陷偶极子运动的角度分析了压电材料中老化、电滞回线异常及电致形状记忆效应等现象的起源, 简要分析了偶极子弛豫现象, 并对未来发展高可靠性压电驱动器的研究作了展望。     

Analysis of an automobile assembly line as a network of closed loops working in both,stationary and transitory regimes

In this work a real automobile assembly line and the correspondent preassembly lines have been analyzed as a network of closed loops of machines decoupled by intermediate buffers. This work deals with some important aspects, which have still not been investigated in earlier literature, such as: machines processing pallets, which are not related to each other and depend on an external variable in a network with closed loops of machines and intermediate buffers, machines working at different cycle times in a network of closed loops of machines and intermediate buffers, machines working in both, stationary and transitory regime and the relationships between the cycle times of the machines in the stationary working regime in order to guarantee the production rate of the system. Finally how the transient results can be used to improve the performance of the system under certain working conditions is discussed.