Elastic buckling of isotropic triangular flat plates by finite elements

Although most of the plates in steel structures are rectangular, some triangular ones do occur. The number of available solutions for triangular plate buckling coefficients is small, and restricted to special triangle geometries and loading ratios. In this paper the range of available solutions is extended by the use of a plate bending finite element devised by Irons. A range of plate parameters is considered and results are tabulated and plotted. The program is available for the use of designers who wish to consider other values of parameters. The use of the procedures described in the Merrison report can extend these results to deal with the influence of initial imperfections and weld effects.     

Thermochemical and thermal analysis on N-(p-methylphenyl)-N'-(2-pyridyl)urea

Low temperature heat capacities of N-(p-methylphenyl)-N'-(2-pyridyl)urea were determined by adiabatic calorimetry method in the temperature range from 80 to 370 K. It was found that there was not any heat anomaly in this temperature region. Based on the experimental data, some thermodynamic function results were obtained. Thermal stability and decomposition characteristics analysis of N-(p-methylphenyl)-N'-(2-pyridyl)urea were carried out by DSC and TG. The results indicated that N-(p-methylphenyl)-N'-(2-pyridyl)urea started to melt at ca. 426 K (153°C) and the melting peak located at 447.01 K (173.86°C). The melting enthalpy was 204.445 kJ mol^-1 (899.6 J g^-1). The decomposition peak of N-(p-methylphenyl)-N'-(2-pyridyl)urea was found at 499.26 K (226.11°C) from DSC curve. This result was similar with that from TG and DTG experiment, in which the mass loss peak was determined as 500.4 K (227.2°C). This revised version was published online in August 2006 with corrections to the Cover Date.     

Minimax estimators for location vectors in elliptical distributions with unknown scale parameter and its application to variance reduction in simulation

In this paper, we give an ever wider and new class of minimax estimators for the location vector of an elliptical distribution (a scale mixture of normal densities) with an unknown scale parameter. The its application to variance reduction for Monte Carlo simulation when control variates are used is considered. The results obtained thus extend (i) Berger's result concerning minimax estimation of location vectors for scale mixtures of normal densities with known scale parameter and (ii) Strawderman's result on the estimation of the normal mean with common unknown variance.Research partially supported by National Science Foundation, Grant #DMS 8901922.     

Photoelectrochemical behavior,XPS and Auger of n-In_2S_3

n-In_2S_3 has been prepared by CVT method.The photoelectrochemical behavior of n-In_2S_3 in a polysulfide redox solution was investigated.It was found that photoetching remarkablyincreased the fill factor.The maximum quantum efficiency of carrier collection reached 95% after 12hirradiation at 100 mW/cm~2 at an applied potential of+1.2V.XPS and Auger analysis were carriedout for examining surface and bulk concentration.The photoetching effect could be satisfactorilyexplained.     

Carbon-13 n.m.r. studies. Part 66—13C spectra of several methyl,hydroxymethyl and carboxylic acid derivatives of bicyclo[2.2.1]heptane and bicyclo[2.2.2]octane

The ¹³C n.m.r. spectra of a series of 52 substituted norbornanes, norbornenes, bicyclo[2.2.2]octanes and -octenes have been recorded to examine the stereochemical effects of closely neighboring substituents on the carbon shieldings of these well-defined molecular frameworks. These moderately rigid skeletons permit detailed examination of a variety of orientations of substituents and, in this study, attention has been focused on a series of vicinally substituted systems. The substituents include methyl, hydroxymethyl and carboxylic acid groups for comparison with earlier data for several bicyclic alcohols and hydrocarbons, from which conclusions regarding the conformational preferences of the hydroxyl group may be drawn. The deviations of the observed shieldings from those predicted by simple additivity follow definite patterns which should be useful for stereochemical assignments in related systems.     

e+e− annihilation scaling plateaus from finite energy sum rules

The consequence of pion-pole dominance in multiperipheral cluster models is investigated. It is shown that the observed size of hadronic total cross sections and the observed average multiplicities are incompatible with the premise that the dominant high energy production is the repeated-pion-exchange in a multiperipheral cluster chain. We discuss implications of our findings and comment on various alternatives for the search of a realistic multiperipheral cluster model.     

Oxygen diffusion and thermal donor formation in silicon

The information available on the diffusion of oxygen and on the formation of thermal donors in silicon is critically reviewed. In this context the effects of intrinsic point defects on the diffusion-controlled growth of oxygen precipitates is investigated in some detail. Seemingly contradictory experimental results on the diffusivity of oxygen in silicon at temperatures around 400° C are explained in terms offast-diffusing gas-like molecular oxygen in silicon. The concept of molecular oxygen is also invoked in a newly suggested model of thermal donor formation in silicon. The diffusivity of molecular oxygen in silicon is estimated to be around 10^–9cm²s^–1 at 450° C, almost nine orders of magnitude higher than the diffusivity of atomic oxygen in interstitial position.     

1.3μm分布反馈二极管激光器组件

开发了一种用于光纤公用天线电视（ＣＡＴＶ）的分布反馈激光二极管组成，组件包括１．３μｍＩｎＧａＡｓ／ＩｎＰ双沟－平面掩埋双异质结（ＤＣ－ＰＢＨ）分布反馈激光二极管和光隔离器，封装在蝴蝶型管壳内，组件的出纤线性功率为２．５ｍＷ，并具有极低的失真。     

Finite difference methods for solving the two-dimensional advection–diffusion equation

Using weighted discretization with the modified equivalent partial differential equation approach, several accurate finite difference methods are developed to solve the two-dimensional advection–diffusion equation following the success of its application to the one-dimensional case. These new methods are compared with the conventional finite difference methods in terms of stability and accuracy. The new methods are more accurate and often more stable than the conventional schemes.