The pipelines used in a ship amount to tens of thousands of metres per ship, and so automatic welding of the pipelines has been widely applied from the viewpoint of saving labour. In most cases the automatic welding process has been used for the welding of butt-joints which can be applied to the pipes in rotary motion, and it has also been used for fillet-welding of the connection between flange and piping. In the butt-welding of fixed pipings, automatic welding processes are now being partly used for position welding but up to the present time automatic welding has seldom been applied to the various types of branch pipe joints in which the welded lines form three-dimensional curves.In recent years, great progress has been made in the technique of constructing steel pipe structures and in the development of practical gas cutting processes to prepare the curves needed for the various welded joints used in piping. This paper deals with various conditions and performance requirements needed for automatic welding, such as the selection of shapes of prepared edges of pipings to be welded, the control of welding positions, the control of welding torches in operation, and the solution and control of other production variables. 相似文献
This paper describes the impacts of mechanical stress on vertical power devices. The stress dependence of the DC characteristics of trench insulated gate bipolar transistors (IGBTs) was measured. The experimental results could be reproduced by the device simulation, which included stress dependence models of the carrier mobility and the band gap. We found that the stress dependence of the on-state voltage mainly arose from the MOSFET portion of the IGBT. Using the device simulation, we estimated the effects of mechanical stress on the surge voltage and the saturation current, which give us the important information for designing a power module with higher ruggedness. 相似文献
For quantitative measurement of microscopical displacement of an object surface due to thermal stress, the holographic pattern measuring system (HPMS) has been developed by the authors, which is combined both the techniques of holographic interferometry and graphic image processing.
In this measuring sytem, a cubic spline function was applied to get the 3-dimensional graphic image patterns of the distribution of the displacement. The displacement is calculated from the interferometry fringe pattern, and the system was applied to deformation analysis of printed circuit board (PCB) due to thermal stress. The PCB deformation was expresed by 3-dimensional graphic image. A smooth curve could be obtained from rather less number of sampled data of interferometry fringe. 相似文献
The numerical problems associated with the full three-dimensional (spatial) distributed parameter filters demand a novel technique that maintains accuracy and efficiency for the complex partial differential Riccati equation governing the filter variance. The filters can be successfully implemented by using numerical operators that can, in various ways, be factored. Use of the finite difference method having this property increases the accuracy and efficiency of the implementation.
This paper outlines a time-splitting technique for the numerical implementation of distributed parameter filters. The paper provides rationales to the square root and U-D factorizations of the distributed parameter filter by means of the time-splitting finite difference method. 相似文献
To develop a method of forming lake sediment into sludge ceramics with porosity and good biological adhesion for use as a medium for microorganisms in wastewater treatment, a study of the effects of forming conditions was conducted by adjusting the water content of sludge and compounding some additives. By adjusting the water content of the raw material at the kneading/pelletizing step to 40–42% and adding 3% waste glass to the raw materials to make up for the lack of flux, a sludge ceramic with a density in terms of specific gravity of saturated surface dry aggregate of about 1400 kg m−3 was formed. In addition, to develop a small-scale wastewater treatment system capable of removing nitrogen and phosphorus, a sludge ceramic was applied as a medium for biological filtration. The results indicated that the BOD removal nitrification rate were superior to those of conventional ceramic media, reached at 95.3% and 87.4%, respectively. The introduction of iron electrolysis resulted in high treatment performance achieving BOD levels of 10 mg L−1 or less, T-N of 10 mg L−1 or less and T-P of 1 mg L−1 or less. 相似文献
The effect of heat treatment on the structure and properties of a plasma-sprayed zircon coating was evaluated. The as-sprayed coating, with open porosity of 10%, is composed of t-ZrO2 and amorphous SiO2 After heat treatment at 1473 K, ZrO2 grows in columnar shape perpendicular to the coating surface, while SiO2 crystallizes to cristobalite. The open porosity decreases to about 5% after the heat treatment. This can be attributed to the sintering of SiO2 and the phase transformation of zirconia. When heat-treated at 1673 K, the coating is composed of ZrSiO4 with dispersed fine m-ZrO2 The open porosity increases again up to 10%. The thermal conductivity of the zircon coating increases with increasing heat treatment temperature. 相似文献
We have demonstrated a significant improvement in the performance of polymer light-emitting diodes (PLEDs) by inserting the fluorene-triatylamine copolymer as hole transport layer (HTL) without a thermal treatment above the glass transition temperature (Tg). A thin HTL insolubilized by a thermal treatment above Tg is often inserted as an interlayer between an anode buffer layer and a light-emitting polymer (LEP) in PLEDs fabricated by using a conventional solution process. The evaporative spray deposition using ultradiluted solution (ESDUS) method has enabled fabricating polymer bilayer structure without an insolublizing procedure. The bilayer PLEDs fabricated by ESDUS without the thermal treatment showed significantly higher and more stable external quantum efficiency than PLEDs having the conventional interlayer. Thermal treatment above Tg of the copolymer would induce degradation of its hole injection property. Furthermore, ESDUS bilayer devices showed much higher power efficiency than interlayer devices when calcium was used for cathode. The improvements would be caused by the enhancement of hole injection and the effective electron blocking at the copolymer/LEP interface in the ESDUS bilayer devices. 相似文献
Various Ti-oxide based photocatalysts such as the highly dispersed Ti-oxide species within zeolite frameworks, TiO2 nano-particles hybridized with hydrophobic zeolite adsorbents as well as visible light responsive TiO2 thin films have been successfully prepared. Characterization studies at the molecular level, such as X-ray absorption fine
structure (XAFS) and photoluminescence (PL), revealed that the highly dispersed Ti-oxide species within the nano-spaces of
zeolites possess a tetrahedral coordination and that they demonstrate unique and high performance for the photocatalytic decomposition
of NOx and the photocatalytic reduction of CO2 with H2O. A high photocatalytic reactivity for the TiO2 semiconducting photocatalysts could be achieved by blending them with hydrophobic siliceous zeolites which was equal to the
performance of TiO2 deposited with expensive Pt particles. The role of the siliceous zeolites can be described as a so-called “catch and release
effect of organic compounds”, i.e., (i) the condensation of the reactants within the hydrophobic cavities of zeolites and;
(ii) the efficient diffusion of the reactant onto the TiO2 photocatalytic sites. Furthermore, a novel photocatalytic system which can convert abundant solar energy into renewable H2 energy by the decomposition of H2O into H2 and O2 can also be achieved by using visible light responsive TiO2 thin film photocatalysts prepared by a RF-magnetron sputtering deposition method. The conversion efficiency of solar energy
into H2 energy may be estimated at ca. 0.1% from the initial rate of H2 evolution. 相似文献
Morphologic control of Pt supported titanate nanotubes was attempted by the hydrothermal hot-pressing (HHP) technique in order to improve the handleability as a photocatalyst. The bulk of Pt-nanocrystal supported titanate nanotubes was successfully fabricated without the H2 reduction process by applying the HHP technique. The bulky Pt-nanocrystal supported titanate nanotubes possessed dense microstructures, significantly sharp distributions of mesopores, and high Brunauer–Emmett–Teller (BET) surface area. Furthermore, the bulky Pt-nanocrystal supported titanate nanotubes showed the photocatalytic degradation activities of 2-propanol aqueous solution under UV-light irradiation. 相似文献
We prepared ultrafine Fe–Pt alloy nanoparticle colloids by UV laser solution photolysis (KrF excimer laser of 248 nm wavelength)
using precursors of methanol solutions into which iron and platinum complexes were dissolved together with PVP dispersant
to prevent aggregations. From TEM observations, the Fe–Pt nanoparticles were found to be composed of disordered FCC A1 phase
with average diameters of 0.5–3 nm regardless of the preparation conditions. Higher iron compositions of nanoparticles require
irradiations of higher laser pulse energies typically more than 350 mJ, which is considered to be due to the difficulty in
dissociation of Fe(III) acetylacetonate compared with Pt(II) acetylacetonate. Au colloid preparation by the same method was
also attempted, resulting in Au nanoparticle colloids with over 10 times larger diameters than the Fe–Pt nanoparticles and
UV–visible absorption peaks around 530 nm that originate from the surface plasmon resonance. Differences between the Fe–Pt
and Au nanoparticles prepared by the KrF excimer laser solution photolysis are also discussed. 相似文献