Accuracy estimation in the finite element analysis of transverse bending of thin flat plates

As a basic study for the establishment of an accuracy estimation method in the finite element method, this paper deals with the problems of transverse bending of thin, flat plates. From the numerical experiments for uniform mesh division, the following relation was deduced, ε ∝ (h/a)^k, k 1, where ε is the error of the computed value by the finite element method relative to the exact solution and h/a is the dimensionless mesh size. Using this relation, an accuracy estimation method, which was based on the adaptive determination of local mesh sizes from two preceding analyses by uniform mesh division, was presented.

A computer program using this accuracy estimation method was developed and applied to 28 problems with various shapes and loading conditions. The usefulness of this accuracy estimation method was illustrated by these application results.     

Test of Lead Glass Shower Counters

Lead glass counters made of wedge shaped blocks of SF6 were tested with positrons at SLAC. The beam energy ranged from 2-17.5 GeV. Energy dependence and beam position dependence of pulse height and energy resolution were studied with lead glass blocks of various lengths. The effect of a BK-7 light guide on pulse height was clearly observed. Degradation of the energy resolution due to aluminum absorbers of various lengths was investigated. A mesh type photomultiplier was also tested.     

Coloration caused by mechanical stress on rare earth oxysulfides

Oxysulfide powders of yttrium, gadolinium, terbium and lanthanum display distinctive colors when they are either heavily ball-milled or pressed in a steel die. These colors are due to optical absorption bands in the visible region, peak positions of which obey an empirical rule like the Mollowo-Ivey relation of color centers in alkali halides. The c-axis shrinks in the colored samples. The colors are bleached and the cell constants are restored to the original values by heat treatment up to 450°C. Some distortions, however, still remain in the annealed samples.     

The explosion of resin moulded power integrated circuits and the corresponding countermeasures

Product Liability (PL) is one of the most serious problems at the present time, but the interest in it is mainly concerned with systems. The authors point out in this paper that one of PL problems is in the parts, namely, the explosion of resin moulded power integrated circuits. There are a few chances of explosion during the test of the units or sets into which they are assembled, due to misoperations such as shorting between the adjacent pins. At that time, a bonding wire or IC chip is overheated due to abnormally high current or power, then the resin fragment just above it is blown off into the air, sometimes burning. This situation is very dangerous and considered to have a possibility of someone becoming blinded.We clarified the explosion mechanism and present some counter-measures to prevent the explosion accident, i.e. some methods of explosion free devices and techniques preventing such accidents.     

Photo-crosslinking of polymeric photobase generator bearing O-acyloxime moieties with low eliminating by-products and high sensitivity

O-Acyloximes are a class of photobase generators (PBGs) that release a primary amine upon irradiation. The generated amine can be used as a crosslinker for polymers bearing epoxy groups, providing a novel photo-induced crosslinking system. However, O-acyloximes also release a ketone by-product that migrates and exudes from the crosslinked polymer. To reduce the migration and elimination of the ketone, 4-vinylacetophenone O-phenylacetyloxime (PaVO) was proposed as a monomeric PBG, and its copolymer with glycidyl methacrylate (PaVO-co-GMA) was compared to poly(glycidyl methacrylate) (PGMA) containing acetophenone O-phenylacetyloxime (PaApO) as a molecular PBG (PaApO/PGMA). Film thickness, infrared (IR), and ultraviolet (UV) spectral changes upon irradiation clarified the vaporization of photoproducts from the PaApO/PGMA films, while such behavior was not observed for the PaVO-co-GMA films. Furthermore, when PaVO-co-GMA was blended with PGMA, less irradiation energy was required for its crosslinking when compared to that of PaApO/PGMA, which contained the same molar ratio of the O-acyloxime unit.     

Amino group introduction onto multiwall carbon nanotubes by NH3/Ar plasma treatment

Multiwall carbon nanotubes (MWCNTs) were modified by using a microwave-excited NH₃/Ar surface-wave plasma. Changes in the atom composition and structural properties of the modified MWCNTs were studied as a function of gas flow rate, treatment time, microwave power, and bias voltage by using X-ray photoelectron spectroscopy and Raman spectroscopy. The results suggest that nitrogen-containing groups were introduced on the surfaces of the MWCNTs and that the concentration of primary amino groups was affected by gas flow rate, microwave power, and bias voltage. The contact angle of water on the modified MWCNTs decreased and the hydrophilicity of the modified MWCNTs was improved. The surface morphology and structure of the MWCNTs were not destroyed by the plasma treatment.     

中型办公楼照明节能控制措施的效果

本文就利用照明控制系统和计量系统对中小型建筑物开展节能活动的情况进行介绍。把相应系统导人中型办公楼,实施多项照明控制措施,对节能效果进行了验证。特别是如何结合各个运行点的使用方式,设置恰当的系统,能获得可喜的节能效果。     

楼宇节能协调控制系统的介绍

本文介绍楼宇设备的节能协调控制系统,该系统随着开放式协议的应用,使空调、照明设施的联动成为可能。目前在楼宇中已经开始推广使用节能协调控制系统。     

Rejection of organic compounds by ultra-low pressure reverse osmosis membrane.

The introduction of ultra-low pressure reverse osmosis (ULPRO) membrane has widened the horizon of reverse osmosis (RO) in purification of surface water and wastewater as well as desalination of brackish water. The ULPRO membrane chemistry can provide a high water flux at low operating pressure, while maintaining a very good salt and organics rejection. This paper deals with the investigation on the rejection of low molecular weight organic compounds by ULPRO membrane. Laboratory scale experiments were carried out at a pressure of 3 kg/cm2 with a feed flow rate of 1.20 l/min. The rejection of undissociated organic compounds did not show a close relationship with the feed pH. The percentage removal of undissociated organic compounds increased linearly with the molecular weight as well as with the molecular width. The removal efficiency can be predicted by these relationships. But neither molecular weight nor molecular width can be considered as an absolute factor for rejection. The feed pH also influenced the removal efficiency of dissociated organic compounds. The efficiency decreased linearly with the increase in the dissociation constant.