非鲁棒路径时滞故障测试生成算法

针对数字电路中非鲁棒路径时滞故障测试时间长、故障覆盖率较低的问题,提出了人工蜂群优化的测试生成算法。该算法首先应用电路转换法则把数字电路转换成为其等效电路,然后用Hopfield神经网络构建等效电路单固定故障的约束电路,并得到能量函数;再应用人工蜂群优化算法计算能量函数的最小值以得到等效电路单固定故障的测试矢量,最后根据对应关系得到原电路非鲁棒路径时滞故障的测试矢量对。在ISCAS’85国际标准电路上的实验结果表明:该算法故障覆盖率能够达到98%,并且平均测试生成时间小于0.8 s。     

基于人工蜂群算法的数字电路多故障测试生成算法

针对数字电路多固定故障测试生成故障覆盖率低和平均测试生成时间长的问题,提出了人工蜂群和神经网络优化的数字电路多固定故障测试生成算法。该算法首先通过等效的方法得到多固定故障的单固定故障模型,再使用Hopfield二值神经网络的方法得到单固定故障的约束电路模型,最后使用人工蜂群优化方法求解故障约束电路接口电路的能量函数的零值点获得原电路的多固定故障的测试生成矢量。实验结果(在ISCAS’85国际标准测试电路上)表明该算法的故障覆盖率可达98.5%以上,平均测试生成时间小于0.25μs。     

一种有效的组合电路测试生成算法

为了改善组合电路测试生成效率,提出了一种有效的基于三值神经网络的组合电路测试生成算法。该算法不需要传播和回溯,而是使用三值神经网络把组合电路表示为双向神经元网络,并构建网络的能量函数,最后使用遗传算法求出全局最小值点作为电路的测试矢量,所以组合电路的测试生成问题转换为优化问题。在标准电路上的测试实验结果表明该算法具有较高的故障覆盖率和较短的测试生成时间。     

基于三值神经网络和混沌搜索的数字电路串扰时滞故障测试生成算法（英文）

提出了一种有效的串扰时滞故障测试生成算法,该算法使用了三值神经网络理论和混沌搜索方法。首先在电路的受害点处把电路分成两个部分,对第一部分,可以得到时滞时间表达式;对第二部分,使用混沌搜索和三值神经网络网络的方法把故障传播到输出端。最后,能够把故障传播到输出端且使时滞时间表达式取最大值的输入矢量就是串扰时滞故障的最优测试矢量。实验结果表明该算法能够容易地得到故障输入测试矢量,平均测试生成时间小于0. 25μs,故障覆盖率能够达到98. 2%。     

基于三值神经网络和混沌搜索的数字电路串扰时滞故障测试生成算法

提出了一种有效的串扰时滞故障测试生成算法,该算法使用了三值神经网络理论和混沌搜索方法。首先在电路的受害点处把电路分成两个部分,对第一部分,可以得到时滞时间表达式;对第二部分,使用混沌搜索和三值神经网络网络的方法把故障传播到输出端。最后,能够把故障传播到输出端且使时滞时间表达式取最大值的输入矢量就是串扰时滞故障的最优测试矢量。实验结果表明该算法能够容易地得到故障输入测试矢量,平均测试生成时间小于0. 25μs,故障覆盖率能够达到98. 2%。     

数字电路阈值故障测试生成算法

提出一种有效的数字电路故障阈值故障测试生成算法。首先构造出数字电路的阈值测试模型,通过这个模型可以区分出可接受故障和不可接受故障,然后使用成熟的固定故障测试生成算法得到不可接受故障的测试生成矢量。在ISCAS’85和ISCAS’89电路上的实验结果表明:该算法的故障覆盖率能达到96%,故障测试生成时间少于0. 019 s。     

基于人工蜂群算法的机器人路径规划

为求解机器人路径规划问题,引入人工蜂群算法,并将路径空间以网格划分,通过固定起始节点和设定最大允许路径节点数等方法,解决了人工蜂群算法应用于路径规划的两个难题--路径节点不固定和邻域构造困难,实现了将ABC算法应用于路径规划问题.通过典型的实例仿真对算法性能进行测试,结果表明:该算法有效克服了停滞行为的过早出现,而且能够加快收敛速度,得到全局最优解或近似解,是解决机器人路径规划问题的一种有效算法.     

改进ABC算法的串联机械臂多目标优化

针对串联机械臂工作时间最优、能耗最优、脉动最优的轨迹优化问题,提出一种基于改进人工蜂群算法的多目标轨迹优化方法。文中采用5次NURBS曲线插值法建立工作轨迹数学模型,构造高阶连续关节运行轨迹并对其进行合理规划。以串联机械臂运行时间、能量消耗和脉动冲击为目标建立目标函数,通过改进人工蜂群算法进行优化设计并获得Pareto最优解集,运用归一化权重目标函数获取期望解。选择PUMA560串联机械臂进行仿真分析,结果表明:5次NURBS曲线轨迹规划方法有效构造平滑轨迹,改进人工蜂群算法能够实现满足约束条件的多目标优化,验证了算法的有效性,为后续研究奠定基础。     

基于人工蜂群算法的双机器人路径规划分析

针对手动液压搬运车车架主焊工序双机器人同步焊接路径规划问题,文中引入虚拟点将多旅行商问题转化为单旅行商问题,选用换位表达编码方式对车架焊缝编码,然后采用基于状态转移策略的人工蜂群算法建立双机器人同步焊接数学模型,仿真求解全局最优焊接路径的较好近似解,并与改进的自适应遗传算法以及人工鱼群算法做了仿真对比试验.结果表明,人工蜂群算法不会过早停滞,具有较快收敛速度,较其它两种算法更能缩短焊接工时,基于人工蜂群算法的双机器人路径规划方法能有效解决搬运车车架主焊工序双机器人同步焊接问题.     

基于改进蜂群算法的焊接机器人路径规划方法研究

针对焊接机器人的运动特点及焊接工作过程中焊枪的避障问题,提出基于改进人工蜂群算法的机器人避障焊接路径规划策略。首先针对传统人工蜂群算法存在的问题,将Lévy(莱维)分布引入到人工蜂群算法侦查蜂寻找新蜜源的过程中,代替其原有0～1之间的随机分布过程,形成了基于Lévy飞行的改进型人工蜂群算法,然后将其应用到焊接机器人的路径规划问题中,并进行了仿真实验。结果表明:改进后的方法能够得到最优的焊接避障路径,且寻优速度快、过程稳定。该方法可用于解决焊接机器人避障路径规划问题。     

RHEOLOGY FEATURE OF SIMPLE METAL MELT

The rheology feature of Sb, Bi melt and alloys was studied using coaxial cylinder high-temperature viscometer. The results showed that the curve of torsion-rotational speed for Sb melt presents a linear relation in all measured temperature ranges, whereas for the Bi melt, the curve presents obvious non-Newtonian feature within the low temperature range and at relative high shear stress. The rheology feature of Sb80Bi20 and Sb20Bi80 alloy melts was well correlated with that of Sb and Bi, respectively. It is considered that the rheology behavior of Sb melt plays a crucial role in Sb80Bi20 alloy and that of Bi melt plays a crucial role in Sb20Bi80 alloy.     

Microstructures and Mechanical Properties of a Newly Developed Austenitic Heat Resistant Steel

The effect of heat treatment on the microstructures and mechanical properties of a newly developed austenitic heat resistant steel(named as T8 alloy) for ultra-supercritical applications have been studied. Results show that the main phases in the alloy after solution treatment are γ and primary MX. Subsequent aging treatment causes the precipitation of M_(23)C_6 carbides along the grain boundaries and a small number of nanoscale MX inside the grains. In addition, with increasing the aging temperature and time, the morphology of M_(23)C_6 carbides changes from semi-continuous chain to continuous network.Compared with a commercial HR3C alloy, T8 alloy has comparable tensile strength, but higher stress rupture strength. The dominant cracking mechanism of the alloy during tensile test at room temperature is transgranular, while at high temperature, intergranular cracking becomes the main cracking mode, which may be caused by the precipitation of continuous M_(23)C_6 carbides along the grain boundaries. Typical intergranular cracking is the dominant cracking mode of the alloy at all stress rupture tests.     

The 15th Global Foundry Sourcing Conference 2014held in Qingdao China

Organized by Suppliers China Co., Ltd and co-organized by the National Technical Committee 54 on Foundry of Standardization Administration of China, the 15th Global Foundry Sourcing Conference 2014 （hereinafter referred to as FSC 2014） was successfully held on Sep. 23rd in Grand Regency Hotel, Qingdao. More than 500 delegates from home and abroad attended this conference, including over 130 purchasers from 20 countries and 380 domestic and foreign suppliers.     

LASER CLADDED TiCN COATINGS ON THE SURFACE OF TITANIUM

Laser cladded coatings of TiCN were produced on the surface of titanium. To obtain the optimal techniques, several conditions were tested by varying the laser scanning rate. The choice of shielding gas was also studied. The cladded coatings were then evaluated from the surface mechanics point of view based on their microhardness. The microstructure of some interesting samples was investigated by optical micrographs (OM). The results showed that under the condition of fixed pulse frequency and pulse width, the laser scanning rate and the shielding gas are the main factors influencing the components of coatings. TiCN coatings were decompounded and oxidized during the cladding process in the condition of no shielding gas of N2. X-ray diffraction results indicated that the composite coatings composed of TiCN, TiC, Ti2N, and TiO2 were produced using appropriate techniques. The results indicated that the best condition in terms of the surface microhardness is obtained when the scanning rate is 1.5mm / s, the pulse frequency is 15Hz, the pulse width is 3.0ms, and N2 is chosen as the shielding gas. The microhardness of the composite coatings is about 1331kg · mm - 2, which is about 4 times that of the substrate. The optical micrographs indicated that the cladding zone is made up of TiCN, TiO2, and some interdendritic Ti, but the diffusion zone mainly consists of the dendrites phase, and the cladded depth is about 80m, which is more than 2 times that of the laser nitrided sample. There were no microcracks or air bubbles in the cladded sample, which was cladded using the above optimal techniques.     

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

X80 pipeline steel plates were friction stir welded(FSW) under air, water, liquid CO_2 + water, and liquid CO_2 cooling conditions, producing defect-free welds. The microstructural evolution and mechanical properties of these FSW joints were studied. Coarse granular bainite was observed in the nugget zone(NZ) under air cooling, and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature reduced. In particular, under the liquid CO_2 cooling condition, a dual phase structure of lath martensite and fi ne ferrite appeared in the NZ. Compared to the case under air cooling, a strong shear texture was identifi ed in the NZs under other rapid cooling conditions, because the partial deformation at elevated temperature was retained through higher cooling rates. Under liquid CO_2 cooling, the highest transverse tensile strength and elongation of the joint reached 92% and 82% of those of the basal metal(BM), respectively, due to the weak tempering softening. A maximum impact energy of up to 93% of that of the BM was obtained in the NZ under liquid CO_2 cooling, which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.     

INDUSTRY NEWS

China Securities News reported on March 21, 2014： Guangdong Hongtu Wuhan Die Casting Co., Ltd. （Wuhan Hongtu）, a wholly owned subsidiary of Guangdong Hongtu Technology （Holdings） Co., Ltd., held a groundbreaking ceremony recently. With the registered capital of 50 million Yuan, Wuhan Hongtu has a total land area of 100,000 square meters and a plant construction area of 72,000 square meters. It is expected to have a production capacity of about 30,000 tonnes of aluminum castings annually after it is put into production.     

GROWTH MORPHOLOGIES OF A BINARY ALLOY WITH LOW ANISOTROPY IN DIRECTIONAL SOLIDIFICATION

Two new classes of growth morphologies, called doublons and seaweed, were simulated using a phase-field method. The evolution of doublon and seaweed morphologies was obtained in directional solidification. The influence of orientation and velocity on the growth morphology was investigated. It was indicated that doublons preferred growing with its crystallographic axis aligned with the heat flow direction. Seaweed, on the other hand, could be obtained by tilting the crystalline axis to 45°. Stable doublons could only exist in a range of velocity regime. Beyond this regime the patterns formed would be unstable. The simulation results agreed with the reported experimental results qualitatively.     

STUDY ON PROPERTIES OF PULSE ELECTRODEPOSITED RE-Ni-W-P-SiC COMPOSITE COATINGS

The effects of pulse frequency f and duty cycle r on the deposition rate, composition, morphology, and hardness of pulse electrodeposited RE （rare earth）-Ni-W-P-SiC composite coatings have been studied. The results indicate that pulse current can improve the deposition rate of RE-Ni-W-P-SiC composite coatings; W, P, and SiC contents in the coating decrease with the increase of pulse frequency and reach the lowest value at f = 33Hz, whereas the RE content in the composite coatings increases with the increase of pulse frequency. SiC content decreases with the increase of duty cycle, W content reaches the lowest value, and P content reaches the highest value at r = 0.4; pulse current and RE can lead to smaller size of the crystalline grains; however, the effects of different pulse frequency and duty cycle on the morphologies of RE-Ni-W-P-SiC composite coatings are not obvious. The hardness of RE-Ni-W-P-SiC composite coatings is the highest when the duty cycle is at 0.6 and 0.8 and pulse frequency is at 50Hz. At the same pulse frequency, the hardness of RE-Ni-W-P-SiC composite coatings at r= 0.8 is higher than that at r= 0.6.     

RELATIONSHIP BETWEEN J-INTEGRAL AND FRACTURE SURFACE AVERAGE PROFILE

To investigate the causes that led to the formation of cracks in materials, a novel method that only considered the fracture surfaces for determining the fracture toughness parameters of J-integral for plain strain was proposed The principle of the fracture-surface topography analysis （FRASTA） was used. In FRASTA, the fracture surfaces were scanned by laser microscope and the elevation data was recorded for analysis. The relationship between J-integral and fracture surface average profile for plain strain was deduced. It was also verified that the J-integral determined by the novel method and by the compliance method matches each other well.