Arc Welding Robot Systems for Large Steel Constructions

This paper describes a sensory-based robot for arc welding, RW-250 family, dedicated to heavy industries which handle large steel constructions. It is required that the arc welding robot for large steel constructions have a wider operation range, narrower space accessibility, and more intelligence than has the conventional one.     

Fine structure of cellophane–acrylamide graft copolymer by the ceric ion method

The relationship between the grafting yield and the structure of graft copolymer is studied by measuring the branched chain lengths, the number of branches, the crystallinities, and the diffraction intensities of the (101) and (101 ) + (002) planes determined by x-ray diffraction, and the distribution of branched polymers, observed by interferometry. Over a relatively wide range of grafting yield the number of initiating sites is almost constant and about 1–2 per 2 moles of cellulose chain. Therefore, the increase of grafting yield seems to be due mainly to the propagation of branched polymers. Branched polymers are assumed to be formed in cellulose crystallites both on the normal (101) planes and in the amorphous regions of cellulose. It is found that branched polymers grow from the outer layer into the inner part of the film as the grafting yield increases. At more than 250% of grafting yield, however, branched polymers are uniformly formed throughout the layer of film in which the crystalline regions of cellulose are gradually destroyed. This result agrees with the dimensional change of gel film during the reaction. The temperature dependence of tensile strength and elongation and the wet strength of graft copolymer are also investigated. At higher grafting yields, such as 250%, the crystalline structure of cellulose is disturbed by the formation of branched polymer, and no improvement in waterproofness can be expected from grafting; the secondary bonding between branched polymers may be presumed to be same as those among cellulose. In addition, the fine cracking of the film in the burst state is found to appear more easily as the grafting yield increases, in which the aggregating state of cellulose is recognized to be changed by the formation of branched polymer.     

The Mechanical Properties of β-SiAlON Ceramics Joined Using Composite β-SiAlON-Glass Adhesives

The mechanical properties of β-SiAlON ceramics joined using β-SiAlON-glass-forming adhesives consisting of mixed Si³N⁴, Y²O³, Al²O³, and SiO² powders are described. Use of adhesives with a β-SiAlON:glass ratio of 60:40 gave an optimum joint strength of 650 MPa in four-point bending mode, i.e., 85% of that of unbonded material, when joining was carried out at 1600°C for 10 min, under an applied uniaxial pressure of 2 MPa. Bonding pressures in excess of 2 MPa caused excessive compressive creep distortion during the joining operation. The strengths of postjoined HIPed material and HIPed, unbonded material, differed by only 4%, i.e., 975 and 1010 MPa, respectively, which indicates that HIPing reduces the size of critical defects in the joint. Fracture toughness of the joint also improved upon HIPing.     

Field Dependence of the Vortex Structure in d-Wave and s-Wave Superconductors

The vortex structure and its field dependence are studied in the clean limit on the basis of the quasi-classical Eilenberger theory to find their difference between - and s-wave pairings. We show the -wave nature and the vortex lattice effect on the local density of states around the vortex, and on the field dependence of the spatially averaged density of states. The -wave pairing introduces a fourfold symmetric structure around each vortex core in the pair potential and the internal field. With increasing field, their contribution becomes significant to the whole structure of the vortex lattice state.     

Study on the development of automatic log scaling system based on machine vision

The conventional log scaling, to get higher accuracy, is done one by one with a tape measure by manual operation. It generally takes more workers working hard for a long time carefully. Here, based on machine vision, a new method is given to scale a bundle of logs at a time. In this scaling process, it is necessary to get the distance between the log-end and camera accurately. Different from general distance calculation, the distance between the log-end and camera is calculated automatically based on the laser triangulation method. It is a seamless integration of image processing and distance calculation. Then the dimensions of each log in the captured images can be transformed to the real ones. In this paper, the relative algorithms are given. And the accuracy of distance calculation is verified with experiments in our lab.     

Discharge through a Permeable Rubble Mound Weir

The hydrodynamics of a rubble-mound weir are theoretically and experimentally examined. This type of weir is considered to be environmentally friendly, since its permeability allows substances and aquatic life to pass through longitudinally. By performing a one-dimensional analysis on a steady nonuniform flow through the weir, discharge is described as a function of related parameters, such as flow depths on the up- and downstream sides of the weir, porosity, and grain diameter of the rubble mound, weir length, etc. A laboratory experiment is carried out to determine the empirical coefficients included in the analytical model. The theoretical solution of the discharge is compared with the experimental data to verify the analysis. It is confirmed that agreement between theory and experiment is satisfactory for a wide range of flow conditions. The present study makes it possible to apply the rubble mound weir for practical use as a discharge control system.     

Prediction of the critical heat flux in annular regime in various vertical channels

The axial variation of film flow rate in annular regime was analyzed to predict the critical heat flux in water saturated flow boiling in various vertical channels. In the analyses, several quantities including the deposition and entrainment rates of droplets were evaluated with the correlations that were based on the separate experimental data of film flow rate and droplet flow rate in annular flow; model closure was achieved without introducing arbitrary constants. The predicted results were compared with extensive data of critical heat flux in flow boiling. Fairly good agreements were observed for the critical heat fluxes in round tubes with uniform and axially non-uniform heating and in non-circular shaped channels without sharp corners. It is hence expected that the important processes for the onset of critical heat flux condition in annular regime were satisfactorily described in the model. However, the critical heat fluxes were generally overestimated in thin rectangular channels with sharp corners. The non-uniform distribution of liquid film in channel cross-section would be the primary reason of the disagreement.     

Preparation of hydroxyapatite/collagen injectable bone paste with an anti-washout property utilizing sodium alginate. Part 1: influences of excess supplementation of calcium compounds

The anti-washout property, viscosity, and cytocompatibility to an osteoblastic cell line, MG-63, of anti-washout pastes were investigated. Mixing a hydroxyapatite/collagen bone-like nanocomposite (HAp/Col), an aqueous solution of sodium alginate (Na-Alg), which is a paste hardening and lubricant agent, and supplementation of calcium carbonate or calcium citrate (Ca-Cit) as a calcium resource for the hardening reaction realized an injectable bone paste. Adding Ca-Cit at a concentration greater than eight times the Ca²⁺ ion concentration to Na-Alg improved the anti-washout property. Although the viscosity test indicated a gradual increase in the paste viscosity as the calcium compounds increased, pastes with excess supplementation of calcium compounds exhibited injectability through a syringe with a 1.8?mm inner diameter, realizing an injectable bone filler. Furthermore, the anti-washout pastes with Ca-Cit had almost the same cell proliferation rate as that of the HAp/Col dense body. Therefore, HAp/Col injectable anti-washout pastes composed of the HAp/Col, Na-Alg, and Ca-Cit are potential candidates for bioresorbable bone filler pastes.     

Self-repairing control via an unstable filter

This paper presents a new self-repairing control system (SRCS) for nonlinear plants with unknown sensor failures of a stuck-type. The SRCS can detect the failure and replace the faulty sensor with the healthy one. The advantage of the SRCS is that no plant model is required to detect the failure. Hence, one can construct the SRCS of an extremely simple structure. To achieve exact and early fault detection, an unstable filter and an auxiliary switching signal are introduced. The detection period can be shortened arbitrarily by choosing a large pole of the filter. Also, this paper shows an application to a nonlinear continuous stirred tank reactor. To confirm the effectiveness, several numerical experiments are explored.