脉冲宽度对云雾回波的影响研究

云雾后向散射会产生引发激光引信虚警的回波信号.基于蒙特卡罗法,对云雾散射回波进行了模拟仿真,并定量给出了云雾散射回波的波形、波峰位置、脉宽和峰值功率随发射脉冲宽度的变化规律.研究结果表明,回波峰值功率随着发射脉宽的增大而增大,且当发射脉宽增大到50ns后趋于饱和,峰值功率将不随脉冲宽度的变化而变化;脉冲展宽的程度随发射脉宽的增大而减弱;发射脉宽对云雾散射回波波峰位置的影响较小.给出的回波信号模拟仿真结果可以为窄脉冲激光引信的目标识别以及探测阈值和脉冲宽度等参量的优化设计提供依据.     

Hydrodynamic approach to multibubble sonoluminescence

The velocity profile and radiation pressure field of a bubble cluster containing several thousand micro bubbles were obtained by solving the continuity and momentum equations for the bubbly mixture. In this study, the bubbles in the cluster are assumed to be generated and collapsed synchronously with an applied ultrasound. Numerical calculations describing the behavior of a micro bubble in a cluster included the effect of the radiation pressure field from the synchronizing motion of bubbles in the cluster. The radiation pressure generated from surrounding bubbles affects the bubble’s behavior by increasing the effective mass of the bubble so that the bubble expands slowly to a smaller maximum size. The light pulse width and spectral radiance from a bubble in a cluster subjected to ultrasound were calculated by adding a radiation pressure term to the Keller–Miksis equation, and the values were compared to experimental values of the multibubble sonoluminescence condition. There was close agreement between the calculated and observed values.     

Thermoelectric generator based on a bismuth-telluride alloy fabricated by addition of ethylene glycol

This paper introduces a new method to selectively fabricate n-type and p-type bismuth (Bi)-telluride (Te) thermoelectric materials by the rate of addition of ethylene glycol (EG) in the Bi–Te co-electrodeposition solution. As the amount of added EG is increased, the atomic ratio of Bi in the deposited Bi–Te alloy reached a slope of 0.463 (at.% of Bi/vol.% of EG), and increased in a linear manner. When the EG content reached approximately 20%v/v, the n-type material changed into a p-type. This change implies that adjusting the EG content in the electrodeposition solution affords simple control of the Bi–Te composition. To demonstrate the applicability of the developed thermoelectric materials, thermoelectric generators (TEGs) were fabricated using electrodeposited n-type (using solution without EG) and p-type (using solution with 30%v/v EG) Bi–Te alloys. The Seebeck voltage of the pair of n-type and p-type thermoelectric materials was 140 mV and the power generated from the pair was 24.36 nW at a 10 °C temperature difference.     

Retention profile and subsequent chemical speciation of chromium (III) and (VI)) in industrial wastewater samples employing some onium cations loaded polyurethane foams

The retention of chromium (VI) from aqueous media onto tetraphenylarsonium chloride (TPAs⁺Cl⁻) or tetraphenylphosphonium bromide (TPP⁺Br⁻) immobilized polyurethane foams (PUFs) was fast and followed first order reaction. The kinetic data of the retention step were subjected to Weber-Morris, Lagergren, Bhattacharya and Venkobachar and Bt kinetic models. The results revealed that, film and intraparticle transport might be the two steps controlling the rate of chromium (VI) sorption from the aqueous acid solutions of pH ∼ zero. The positive values of the Δ H of chromium (VI) retention by the reagents loaded PUFs were interpreted as an endothermic process. Under the optimum pH (pH ∼ zero ) of the aqueous solution, the proposed TPAs⁺Cl⁻ or TPP⁺Br⁻ immobilized PUFs was successfully used in a series of medical syringe (30, 50 mL capacity) as pulse columns for complete collection of chromium (VI) species present in fresh and industrial wastewater samples at ultra trace low level of chromium (VI) (≤ 0.05 μg mL^− 1). The collected chromium (VI) species onto TPAs⁺Cl⁻ or TPP⁺Br⁻-PUFs was then stripped quantitatively (98-102 ± 2.6%) from the pulse columns with NaOH (2.0 mol L^− 1) and subsequently analyzed photometrically. The chromium (VI) ions could be pre concentrated up to 100-fold from large volume of water samples. The proposed pulse foam columns were applied successfully for complete collection, recovery (97.5 ± 2.6%, n = 5) and subsequent chemical speciation of chromium (III) and (VI) in wastewater samples. The results are in good agreement with the reported and standard methods at 95% confidence.     

Luminescent and dosimetric properties of ultrafine magnesium oxide ceramics after high dose irradiation

The luminescent and dosimetric properties of ultrafine MgO ≿eramics synthesized in strongly reducing conditions at Т = 1100–1400 °С are investigated. The growth of photo- and cathodoluminescence output at 2.0–3.5 eV (400–600 nm) is found. It is due to an increase in concentration of single oxygen vacancies and their aggregates. It was established that thermal treatment leads to TL intensity growth after high dose irradiation of the samples by a pulsed electron beam (130 keV). The tunneling mechanism of charge carriers' recombination occurs after this treatment as well. The presence of tunneling recombination is proved by the analysis of the shape and temperature dependence of TL isothermal decay curves. The possibility of using synthesized ceramics for high dose TL dosimetry of ionizing radiations is shown.     

基于马赫曾德干涉光路的光压测量装置设计

基于马赫曾德干涉原理,设计搭建了可调制与放大干涉条纹的光压测量装置.由频率和功率可调制脉冲激光产生光压,使真空中两面高反镀铝薄膜产生微小形变(位移),从而使由氦氖激光器发射、经半反半透镜分束的参考光和信号光的光程差改变,即干涉条纹发生改变.用CCD记录干涉条纹位移量,数据处理获得干涉条纹位移量和薄膜形变量的关系,计算出脉冲激光在薄膜处的光压.分别讨论了脉冲激光入射角度、频率等参量对检测结果的影响,并通过双角度入射方法消除了热辐射效应的影响.该检测装置可测得最小光功率为15.0mW所产生的光压大小为13.42μPa,线性工作范围为15.0mW(13.42μPa)至200mW(1179μPa),且工作稳定、灵敏度高,测量结果准确.     

离子排斥色谱-脉冲安培法测定电镀液中的游离CN-

建立了离子排斥色谱-脉冲安培法测定游离CN-的检测方法。方法使用IonPac ICE-AS1离子排斥柱为分析柱,以120 mmol/L HClO4为淋洗液,安培法检测（工作电极为Pt电极）。CN-的检出限为0.42μg/L（50μL进样,三倍基线噪音）;在1-1000μg/L范围内具有良好的线性（r=0.9996）。0.01 mg/L和0.1mg/LCN-分别连续进样9次,峰面积相对标准偏差（RSD）分别为4.0%和3.0%。用该方法检出了电镀液样品中大量的游离CN^-。对实际样品进行加标,其回收率在83%-117%之间。     

脉冲辐解研究喹啉和异喹啉与瞬态粒子的反应

通过合理控制反应条件, 使体系在电子束脉冲作用后只剩下所需要的一种瞬态粒子, 用脉冲辐解研究了喹啉、异喹啉分别与水合电子、羟基自由基、氢自由基等几种典型的氧化还原瞬态粒子的反应过程, 研究了各种瞬态产物的吸收光谱及其变化规律, 测定了相关反应的速率常数. 喹啉、异喹啉与水合电子的反应速率常数分别为7.1×10⁹和3.4×10⁹ mol^-1·L·s^-1, 与羟基自由基的反应速率常数分别为7.2×10⁹和3.4×10⁹ mol^-1·L·s^-1, 与氢自由基的反应速率常数分别为5.7×10⁹和3.6×10⁹ mol^-1·L·s^-1. 这一结果表明, 喹啉、异喹啉均能够非常迅速地与水合电子、羟基自由基、氢自由基发生反应, 喹啉比异喹啉的反应速率更快. 运用电子理论分析了瞬态反应产物结构的稳定性差异, 结果表明, 喹啉的反应产物比异喹啉的稳定, 从而揭示了喹啉比异喹啉反应速率快的原因.     

脉冲条件下ITER HCCB TBS动态氚输运分析

在ITER脉冲运行条件下对中国氦冷固态增殖剂实验包层系统(HCCB TBS)动态氚输运进行了分析,利用Modelica语言开发了一套动态氚分析程序.对比了在脉冲运行工况及连续运行工况下TBS流体中的氚浓度和分压的动态变化、固体材料中氚盘存量的动态变化以及氚渗透通量的动态变化.脉冲运行下TBS系统氚变化趋势与物理分析结果...