力学化学效应对LY12CZ铝合金点蚀行为的影响

利用电化学测量技术研究了加载弹性载荷对LY12CZ铝合金在3％NaCI溶液中的自腐蚀电位、点蚀电位和保护电位的影响规律，同时利用小孔发展速率（PPR）-电位曲线法和电位扫描技术及显微测量技术研究了载荷对预选电位下的真实小孔发展速率的影响，根据点蚀电流密度随应力变化情况来研究力学化学作用对LY12CZ点蚀敏感性的影响，结果表明在加载应力时，LY12CZ铝合金的自腐蚀电位、保护电位和破裂电位都有不同程度的负移，负移的量取决于应力的大小。在加载应力时点蚀电流密度随应力增加也出现增大的现象，研究结果表明力学化学效应对LY12CZ铝合金的点蚀行为有显著影响。     

SrTiO3微纳米线的制备与亲疏水性

采用水热法，使用层状钛酸盐纳米线和氢氧化锶作为前驱物，在一定反应温度和反应时间的条件下简单地制备出了超细SrTiO3粉体。结果表明，只有在反应条件和反应物配比合适时才能得到纯的SrTiO3粉体。用X-射线粉末衍射仪和扫描电镜对SrTiO3粉体进行了表征。结果表明，所制备的SrTiO3粉体绝大部分为线状，长度约20μm，直径100～500nm。用接触角仪对所制备的SrTiO3粉体的亲疏水性进行了研究。结果表明，随着反应时间的延长，反应产物SrTiO3的纯度逐渐增加，由原来的完全亲水性转变为疏水性，接触角为36．820。     

Direct laser fabrication of thin-walled metal parts under open-loop control

Direct laser fabrication (DLF) is an advanced manufacturing technology, which can build full density metal parts directly from CAD files without using any modules or tools. The investigation on the fabrication of thin-walled parts of nickel alloy using open-loop DLF process is introduced in this paper. The experimental setup consisted of a CO₂ laser, a 3-axis CNC table, a coaxial powder nozzle and a powder recycler. The 3D-CAD file of a thin-walled metal part was converted into the STL file format and imported into software HUST-RP to generate ‘pseudo-random’ scanning paths of laser beam. The influence of process parameters on the build height of thin-walled metal parts was studied by 1–10 layered single-bead stacks of nickel alloy. The result shows that the interference factors which affect the build height of thin-walled metal parts occur randomly during the process. For open-loop DLF process, thin-walled metal parts can achieve much better shape quality if the process parameters are suitable. Multilayer single-bead walls were built up with different scanning velocity to obtain the optimal process parameters of thin-walled parts of nickel alloy. It shows that thin walls of nickel alloy with uniform height can be built up layer by layer in a certain range of specific energy. However, it is difficult to control the build height of complex thin-walled metal parts in an accurate manner just using optimal parameters. A special coaxial powder nozzle was designed in this paper. In a certain range, the deposition thickness of the nozzle is nearly linearly increased with increase in the standoff distance between the powder focusing point of the nozzle and the deposition substrate. By means of the nozzle, a novel method to control the build height of thin-walled metal parts using open-loop DLF process was introduced. The difference in build height of a thin-walled part can be compensated automatically in one or several layers during the process. It is proved that the build height of a thin-walled metal part can be accurately controlled in theory using the nozzle. A complex single-bead part of nickel alloy whose geometry was designed to be the well-known Chinese ‘FU’ was fabricated and explained in this paper. The result shows that the shape quality of the sample is quite good, and actual build height of the sample is 53.54 mm while the designed value is 54 mm.     

防锈铝表面喷丸强化冲击试验研究

采用仪器化（数字化）冲击试验机，对防锈铝表面喷丸强化后进行冲击试验，试验结果表明：喷丸后的最大冲击力比母材提高35％，最大力前弹塑性变形功提高166％。     

Synthesis and characterization of LiNi0.95-xCoxAl0.05O2 for lithium-ion batteries

Samples of LiNi0.95-xCoxAl0.05O2 （x = 0.10 and 0.15） and LiNiO2, synthesized by the solid-state reaction at 725℃ for 24 h from LiOH-H2O, Ni2O3, Co2O3, and AI（OH）3 under an oxygen stream, were characterized by TG-DTA, XRD, SEM, and electrochemical tests. Simultaneous doping of cobalt and aluminum at the Ni-site in LiNiO2 was tried to improve the cathode performance for lithium-ion batteries. The results showed that co-doping （especially, 5 at.% A1 and 10 at.% Co） definitely had a large beneficial effect in increasing the capacity （186.2 mA.h/g of the first discharge capacity for LiNio.s.42OoaoAlo.0502） and cycling behavior （180.1 mA-h/g after 10 cycles for LiNio.85CooaoAlo.osO2） compared with 180.7 mA.h/g of the first discharge capacity and 157.7 mA.h/g of the tenth discharge capacity for LiNiO2, respectively. Differen- tial capacity versus voltage curves showed that the co-doped LiNio.95_xCoxmlo.osO2 had less intensity of the phase transitions than the pristine LiNiO2.     

基于环境激励的桥梁振动模态识别算法研究

在桥梁建造和维护过程中,需要对桥梁的振动模态进行在线、实时的分析,急需一种不需要人工激励进行快速模态分析的算法。通过研究自然激励技术NExT( Natural Excitation Technique)与自回归滑动平均模型ARMA( Auto￣Regressive and Moving Average Model),在常规的自然环境模态分析算法的基础上构造出一种快速求解NExT￣ARMA模型的算法进行桥梁模态识别。相比于传统的环境激励模态参数计算方法,该算法不但降低了传统算法的复杂度,而且采用了反馈的方式提高了计算精度。采用ANSYS建立有限元模型并搭建简易实验系统分别对该算法进行仿真验证和实验验证,验证结果表明,该算法能够有效地在自然激励下提取出桥梁结构的各阶模态,其中对前三阶固有频率的识别相对误差降到1％左右。     

Integrated guidance and control design based on a reference model

In this paper, an Integrated Guidance and Control (IGC) algorithm based on a reference model is proposed for a side-jet missile. First, a IGC structure is introduced, incorporating the response characteristics of the missile control loop into the guidance loop. To describe the response characteristics, then a reference model is built. Next, with the back stepping scheme and sliding mode control algorithm, the reference model is adopted to derive a novel guidance law, which contains response parameters of missile control system to formulate the IGC design. Finally, simulations and comparisons with the time-scale separation design and an existing IGC design, are conducted to verify the proposed IGC algorithm. It can be shown that the proposed algorithm performs better against highly maneuvering target in different missile-target initial position and heading scenarios.     

Aggregate‐induced emission in light‐emitting liquid crystal display technology

Nowadays, liquid crystal displays (LCDs) with light‐emission are considered as energy‐efficient devices and are promising alternatives to conventional LCDs. To realize such possibility, strong fluorescent materials with a dichroic properties are required. Aggregate‐induced emission (AIE) is an unusual photophysical phenomenon shown by some luminogenic materials that will be highly emissive in their aggregate state. In this work, we studied the AIE effect of a luminescent liquid crystalline molecule TPE‐PPE in our LC system as a luminophore dopant. The result showed the excellent AIE effect that higher concentration of luminogen in the nematic LC host induced stronger luminescent intensity. Through exposure of a photoisomeriable alignment material sulfonic‐dye‐1, the photopatterning of a light‐emitting LC device was achieved with the use of the TPE‐PPE/nematic LC mixture.     

Morphological image fusion using the extracted image regions and details based on multi-scale top-hat transform and toggle contrast operator

Remaining useful information of the original images in the fusion image is very important in image fusion. To be effective for image fusion, a multi-scale top-hat transform and toggle contrast operator based algorithm using the extracted image regions and details is proposed in this paper. Top-hat transform could extract image regions, and operations constructed from toggle contrast operator could extract image details. Moreover, multi-scale top-hat transform and toggle contrast operator could be used to extract the effective image regions and details at multi-scales of the original images. Then, the extracted image regions and details are imported into the final fusion image to form the effective fusion result. Thus, the proposed multi-scale top-hat transform and toggle contrast operator based algorithm is an effective image fusion algorithm to keep more useful image information. The combination of the top-hat transform and toggle contrast operator for effective image fusion is the main contribution of this paper, which is the extension of the previous work using only the toggle contrast operator for edge preserved image fusion. Experimental results on multi-modal and multi-focus images show that the proposed algorithm performs very well for image fusion.     

Adaptive dynamic surface control of a hypersonic flight vehicle with improved tracking

This work presents a nonlinear adaptive dynamic surface air speed and a flight path angle control design procedure for the longitudinal dynamics of a generic hypersonic flight vehicle. The proposed design scheme takes into account the magnitude, rate, and bandwidth constraints on the actuator signals. A new approach is used to enhance tracking performance and avoid a large initial control signal. The uncertain nonlinear functions in the flight vehicle model are approximated by using radial basis function neural networks. A detailed stability analysis of the designed controllers shows that all the signals of the closed‐loop system are uniformly ultimately bounded. The robust performance of the design scheme is verified through numerical simulations of the flight vehicle model for various parameter variation test cases. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society