High-T/sub 0/ strain-compensated InGaAsSb-AlGaAsSb quantum-well lasers emitting at 2.43 /spl mu/m

Strain-compensated InGaAsSb-AlGaAsSb quantum-well (QW) lasers emitting near 2.5 /spl mu/m have been grown by solid-source molecular beam epitaxy. The relatively high arsenic composition causing a tensile strain in the Al/sub 0.25/GaAs/sub 0.08/Sb barriers lowers the valence band edge and the hole energy level, leading to an increased hole confinement and improved laser performance. A 60% external differential efficiency in pulsed mode was achieved for 1000-/spl mu/m-long lasers emitting at 2.43 /spl mu/m. A characteristic temperature T/sub 0/ as high as 163 K and a lasing-wavelength temperature dependence of 1.02 nm//spl deg/C were obtained at room temperature. For 2000 /spl times/ 200 /spl mu/m/sup 2/ broad-area three-QW lasers without lateral current confinement, a low pulsed threshold of 275 A/cm/sup 2/ was measured.     

微胞囊技术及产品F-500多功能灭火剂

介绍了微胞囊技术及产品F-500的灭火原理和优势。     

Information analysis of single photon emission computed tomography with count losses

An analysis is presented of the information transfer from emitter-space to detector-space in single photon emission computed tomography (SPECT) systems. The analysis takes into account the fact that count loss side information is generally not available at the detector. Side information corresponds to the number gamma-rays lost deleted due to lack of interaction with the detector data. It is shown that the information transfer depends on the structure of the likelihood function of the emitter locations associated with the detector data. This likelihood function is the average of a set of ideal-detection likelihood functions, each matched to a particular set of possible deleted gamma-ray paths. A lower bound is derived for the information gain due to incorporating the count loss side information at the detector. This is shown to be significant when the mean emission rate is small or when the gamma-ray deletion probability is strongly dependent on emitter location. Numerical evaluations of the mutual information, with and without side information, associated with information-optimal apertures and uniform parallel-hole collimators are presented.     

Preparation and properties of close-packed composite materials

Monodisperse silica particles of about 0.3m diameter are suspended in methacrylate monomer using a carefully selected dispersant. Many steric dispersants are hydrocarbon chains with a reactive end-group. These are not effective as dispersants for silica in moderately polar solvents, such as esters and the methacrylate monomers. Good dispersion was obtained with a methacrylate polymer terminated by a chlorosilane end group. Settling or centrifugation of these unagglomerated dispersions gives well-packed particle beds. Polymerization of the surrounding monomer produces composite materials with high packing fractions and a high degree of regularity. Moduli and strengths of these composites are reported.     

Study on heat conduction and adsorption/desorption characteristic of MIL-101/few layer graphene composite

Journal of Porous Materials - Aiming at the poor heat conduction performance of porous MIL-101 applied in adsorption cooling process, few layer graphene (FLG) was selected as a promising thermal...     

电动车制动能量再生反馈控制研究

研究了电动汽车制动过程中的能量回馈，设计了混合励磁无刷电动机在汽车制动过程的能量再生反馈控制系统。以脉宽调制调压调速系统为例，研究各种制动态下的能量回馈过程。并将其安装在EV6600电动汽车上进行试验，结果表明：该控制系统可达到10%左右的能量回收效率。     

碱土金属在萃取剂与树脂间反应平衡常数的测定

研究了碱土金属离子在Ｄ００１树脂与８－羟基喹啉三氯甲烷溶液间的平衡常数Ｏ－ｔＫ的测定。其值依Ｍｇ、Ｃａ、Ｓｒ、Ｂａ次序减小。并得出萃取剂浓度［ＨＡ］。与金属离子在两相分配的关系。     

Cu2O/Cu Cermet as a Candidate Inert Anode for Al Production

Cu₂O/ x Cu ( x =0–25 wt%) cermets were evaluated as a novel partially inert anode for aluminum (Al) production. The physical and mechanical properties, including the compressive strength, flexural strength, thermal expansion coefficient, thermal conductivity, and dc electrical conductivity were tested at room temperature and at temperatures up to 950°C. The coefficient of thermal expansion, compressive strength, flexural strength, thermal conductivity, and electrical conductivity of Cu₂O/Cu cermets increased with increasing Cu content. High-temperature electrical conductivity measurements showed that with increasing temperature, the electrical conductivity increased when the Cu content was below the percolation threshold, while it decreased when the Cu content was above the percolation threshold. A relatively stable CuAlO₂ layer formed on the cermet surface during electrochemical testing, and the corrosion rate of this anode was estimated to be about 1.8–1.9 cm/year in Al production.     

乳白玻璃条纹解决方案

对乳白玻璃瓶表面产生条纹的原因进行分析,通过耐火材料选用、稳定熔制工艺、工作池中层取料和供料道加搅拌的方法消除条纹缺陷。     

Formation Mechanisms of Platelet Sr3Ti2O7 Crystals Synthesized by the Molten Salt Synthesis Method

The molten salt synthesis (MSS) method is utilized to synthesize the anisotropic platelet Sr₃Ti₂O₇ (S3T2) single-crystal particles. The aim of this study is to identify the essence of platelet Sr₃Ti₂O₇ crystal growth and guide the synthesis of anisotropic platelet SrTiO₃ crystals as well as various technologically important materials. Based on the results of X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy, the formation mechanism of platelet Sr₃Ti₂O₇ crystals conforms to a nucleation–structure rearrangement–dissolution–diffusion in situ epitaxial growth mechanism model. First, SrCO₃ reacts with TiO₂ to form submicrometer SrTiO₃ nuclei. Then, most of the nuclei surrounded by salt ions aggregate and rearrange to form a large SrTiO₃ matrix. The structural rearrangement and the subsequent in situ epitaxial growth processes control the morphology, composition, and size of the final Sr₃Ti₂O₇ crystals. In the synthesis process, the conversion between SrTiO₃ and Sr₃Ti₂O₇ is as follows: and the crystallographic orientation relationship between Sr₃Ti₂O₇ and SrTiO₃ in the interface is (100)_S3T2//{100}_ST, (010)_S3T2//{010}_ST, and (001)_S3T2//{001}_ST.