Advanced Statistical Methods in Biometric Research.

An overview of the achievements of the German priority program “Functionally Graded Materials (FGM)” in the field of processing techniques is given. Established powder processes and techniques involving metal melts are described, and recent developments in the field of graded polymer processing are considered. The importance of modeling of gradient formation, sintering and drying for the production of defect-free parts with predictable gradients in microstructure is discussed, and examples of a successful application of numerical simulations to the processing of functionally graded materials are given.

Processing techniques for functionally graded materials

This paper reports the development of a robotic system designed to extend a human’s ability to perform small-scale (sub-millimeter) manipulation tasks requiring human judgment, sensory integration,...

A Steady-Hand Robotic System for Microsurgical Augmentation

Cemented carbides cover a wide range of applications in many relevant industries, i.e. as cutting tools (turning, milling, drilling) for machining of metal components in the automotive and/or aerospace industry, as components of drill bits or road headers in the rock tools and mining area or as wear parts in wire drawing dies or punch tools. In this review selected cemented carbide and cermet microstructures are presented. The focus is on microstructures, both those that are already established in the cemented carbide industry and those which have drawn scientific attention due to new potential applications. Cemented carbides are here divided in four groups based on microstructure and chemistry: WC morphology and chemistry, cubic carbide containing cemented carbide and cermets, functionally graded cemented carbides, and binder design of cemented carbides. Furthermore, this review covers some historical background that motivated the microstructure design as well as the status of each class of materials nowadays. The paper aims at categorising cemented carbides in a structured way and to serve as an introduction to cemented carbide microstructures for engineers, researchers and scientists.

Cemented carbide microstructures: a review

Cemented carbides are, from a technical point of view, one of the most successful composite materials. The physical and chemical aspects of the components (transition-metal carbides and iron-group metals) and of their interaction in hardmetals are reviewed with emphasis on the materials science point of view focusing on those compositions which have gained technical interest. Crystal structures and phase relationships are discussed in detail. The interaction of components (wetting, residual stresses) and some microstructural aspects (size, contiguity, and shape) are treated also. These fundamentals are the basis of understanding the production processes and the properties of cemented carbides.

Physical and chemical nature of cemented carbides

The grain size of WC-20%Co alloy affected by the addition carbides such as TiC, VC, Cr3C2, ZrC, NbC, Mo2C, HfC and TaC was in detail investigated. Specimens were sintered mainly at 1400°C for 1 hr. The mean grain size of starting WC powder was about 0.6μ.Results obtained were as follows: (1) When the liquid phase was saturated by the addition carbides at sintering temperatures, the restriction effect of VC on the grain growth of WC was the largest, followed by Mo2C, Cr3C2, NbC, TaC, TiC, ZrC(≅HfC). In this case, there existed a strong correlation. between the restriction effect of addition carbides and the solubility limit in the liquid phase (or the formation free energy). (2) On the other hand, when the liquid phase contained a certain amount of dissolved metals of addition carbides, i.e., about 1.5at% for the starting Co, the effectiveness was in the following order; VC>NbC>TaC>TiC>Mo2C>Cr3C2>ZrC≅HfC. (3) Considering the restriction effect and the shape of carbides precipitated, VC addition was considered to be the most suitable for the grain growth inhibitation of WC, followed by Cr3C2, NbC and TaC.

https://www.jstage.jst.go.jp/article/jjspm1947/19/2/19_2_67/_pdf

Effects of Addition Carbides on the Grain Size of WC-Co Alloy

A class of simple learning control algorithms with a forgetting factor and a long-term memory and without use of the derivative of velocity signals is proposed for motion control of robot manipulators. The robustness of search learning laws with respect to initialization errors, fluctuations of the dynamics, and measurement noises is studied extensively. As a result the uniform boundedness of motion trajectories is proved based on the passivity analysis of robot dynamics. It is also proved that motion trajectories converge to a neighborhood of the desired one and eventually remain in it provided the content of the long-term memory is refreshed adequately after a sufficient number of trials. >

Robustness of P-type learning control with a forgetting factor for robotic motions

The β-Free Layer Formed near the Surface of Vacuum-Sintered WC–β–Co Alloys Containing Nitrogen

A class of learning control algorithms with a forgetting factor 1> alpha >0 and without differentiation of velocity signals is proposed, which updates the input by u/sub k+1/=(1- alpha ) u/sub k/+ alpha u/sub 0/+ Phi e/sub k/, where u/sub k/ and e/sub k/ stand for command input and velocity error at kth exercise, respectively. The robustness of this learning control with respect to reinitialization errors, fluctuation of dynamics, and measurement noise is studied. It is shown that the exponential passivity of displacement robot dynamics plays a crucial role in the uniform boundedness of transient behaviors and the convergence in the progress of learning. A method called selective learning, which updates u/sub 0/ in the long-term memory by selecting the best command among the past several trials, is proposed. It is claimed that this method accelerates the speed of convergence. >

Selective learning with a forgetting factor for robotic motion control

This paper proposes a method of, given a multilevel image called a reference image in which an arbitrary shape S lies and another multilevel image called an input image in which one shape rotated and parallel translated from S lies, computing the angle of rotation and the quantity of parallel translation. This method applies a modified version of the Hough transform proposed by O'Gorman and Clowes (1976) to the reference and input images, and computes the angle of rotation uniquely. Moreover, this method needs no extracting feature points, and is applicable to low quality images.

Hisashi Suzuki

Papers

Effects of Addition Carbides on the Grain Size of WC-Co Alloy

Robustness of P-type learning control with a forgetting factor for robotic motions

The β-Free Layer Formed near the Surface of Vacuum-Sintered WC–β–Co Alloys Containing Nitrogen

Selective learning with a forgetting factor for robotic motion control

Detection of rotation and parallel translation using Hough and Fourier transforms