Interfacial structures and mechanical properties of steel–Ni and steel–Ti diffusion bonds

Static and fatigue shear tests of steel–Ni bonds and steel–Ti bonds were carried out to obtain the relations between the strengths and the bonding conditions. Ultrasonic measurements were also made to examine the relations between the strengths and the size of the bonded region (the estimated diameter). At the bonding interface of the steel–Ni bonds, no intermediate phase was observed. At the bonding interface of the steel–Ti bonds, a thin layer of intermetallic compound was formed at lower bonding temperatures but, at higher bonding temperatures, the interlayer melted and the bonding interface became rough. The intensity of the ultrasonic wave reflected from the bonding interface changed, depending on the state of the bonding interface. In shear tests of the steel–Ni and steel–Ti bonds, cracks propagated along the bonding interface, and the strength was proportional to the square of the estimated diameter. In fatigue tests, cracks propagated in the thickness direction of the plate and no relation was obtained between the fatigue life and the estimated diameter. Fatigue life distributions were represented by two- and three-parameter Weibull distributions. This revised version was published online in November 2006 with corrections to the Cover Date.     

Dielectric and Piezoelectric Properties of Pb(Co1/3Nb2/3)O3-PbTiO3-PbZrO3 Solid Solution Ceramics

Ceramic and piezoelectric properties of the Pb(Co_1/3Nb_2/3)O₃-PbTiO₃-PbZrO₃ system were investigated. The system contains rhombohedral, tetragonal, and pseudocubic phases at room temperature. The triple point is at 0.07Pb(Co_1/3Nb_2/3)O₃-0.43PbTiO₃-0.50PbZrO₃. High dielectric constants (750 to 1500) and radial coupling coefficients (40 to 45%) and low average temperature coefficients of resonant frequency (of the order of 10^-6°C) were obtained for compositions near the morphotropic phase boundary.     

A Flux‐Modulating Synchronous Machine with Permanent Magnet Excitation

This paper presents a novel type of flux‐modulating synchronous machine (FMSM) in which permanent magnets (PMs) are embedded in the stator back‐iron. The rotor has neither windings nor PMs. A prototype machine with an outer‐rotor configuration was designed and manufactured to validate the operating principle of the FMSM. The characteristics in the motor mode of the prototype machine were also investigated with a vector control system. The results of the investigations show that, as in surface‐mounted PM motors, the torque of the FMSM is predominantly generated by the PM flux and can be controlled using the armature current.     

新型可见光固化树脂

针对一些过氧化物固化不能满足特殊的施工环境,以及紫外光固化存在对人体有害、应用范围窄、厚膜固化性不好等缺点,开发了1种利用可见光光源进行固化的变性乙烯基酯树脂(VLC树脂),通过测定其黏度、比重、酸价、力学性能、Tg、热变形温度、积层板在一定浓度的酸、碱、水、有机溶剂等介质里面的强度保持率,分别对树脂液态特性、树脂浇铸体及积层板的力学性能以及积层板的耐腐蚀性能进行了表征,通过与一般的过氧化物固化的乙烯基酯树脂的浇铸体及积层板性能比较,可以看出:可见光固化与常见的过氧化物固化相比,性能相当甚至更佳,并且可见光固化速度极快,苯乙烯挥发极少,作业简单,无须加促进剂和固化剂,无须繁琐的搅拌和脱泡过程,提高生产效率的同时,大幅度降低施工成本。     

Computational complexity of spline interpolation

The procedure for composing the spline function of order m that interpolates n data is roughly divided into two stages: (1) constructing the matrix A_n that transforms the fl-spline coefficient vector c into the sample value vector s; and (2) calculating the vector c. Then the effects of boundary conditions and the locations of the sampling points and the knots on the number of computations for spline interpolation are evaluated. There are no boundary condition effects of the construction of A" for equispacing. Non-periodic boundary conditions reduce the number of computations needed to calculate c from O(m²n) to O(m²n/4).

In the construction of A_n, choosing equispaced sampling points reduces the number of computations from O(m²n) to O(m²) in the case of sampling points located at a constant interval between each pair of adjacent knots. In the calculation of c, equispaced sampling points reduce the number of computations from O(m²n) to O(m²n /2) in the case where m is even and the locations of the knots are identical with those of the sampling points.     

Decentralized adaptive control of robotic manipulators†

We develop a self-tuning-type adaptive control for robotic manipulators with six joints, and analyse the stability of the control system. In order to reduce the computational effort for obtaining the control input in real time, a decentralized adaptive control system is designed in which each joint of the manipulator is regarded as a subsystem and controlled independently in parallel. In this control system we regard the interaction among the multiple joints as an unknown input in each subsystem. The influence of the interaction on the stability of the overall control system is analysed using a Lyapunov function. The theoretical result obtained is that the control system is always stable in the sense that the error between the output of the adaptive predictor and the real output (angular velocity of each joint) will not exceed the amount of interaction. This result is verified by some simulation studies.     

Criterion for conditional stability of Ml MO integral control

A simple criterion to detect the conditional stability of MI MO systems with integral control is described, It is shown that a closed-loop system with a loop-transfer matrix H(s)/s is made unstable by undesirable feedback-gain reduction if any of the principal minors of [si - H(0)] have zeros in the left half-plane.