Improved design and construction of an ionization chamber for the CSNS beam loss monitor (BLM)

Based on the first ionization chamber (IC) prototype, the structure, working gas component and electrode material of the IC are improved. The test of the improved IC shows that the plateau length is about 2000 V, the plateau slope is less than 0.2%/100 V, the sensitivity is 19.6 pA/rad·h^-1, the up-limitation of the linearity can be up to 3.6×10⁵ rad/h, and the applied voltage can be operated to 3500 V. The test results show that the performance of the improved IC meets the requirements of the beam loss monitor.     

Bcklund Transformation and Conservation Laws for the Variable-coefficient N-Coupled Nonlinear Schrdinger Equations with Symbolic Computation

Considering the integrable properties for the coupled equations, the variable-coefficient N-coupled nonlinear Schrdinger equations are under investigation analytically in this paper. Based on the Lax pair with the nonisospectral parameter, a Bcklund transformation for such a coupled system denoting in the Γ functions is constructed with the one-solitonic solution given as the application sample. Furthermore, an infinite number of conservation laws are obtained using symbolic computation.     

Design and construction of the first prototype ionization chamber for CSNS and PA beam loss monitor (BLM) system

Design and construction of the first prototype ionization chamber for CSNS and Proton Accelerator (PA) beam loss monitor (BLM) system is reported. The low leakage current (<0.1 pA), good plateau (≈800 V) and linearity range up to 200 Roentgen/h axe obtained in the first prototype. All of these give us good experience for further improving the ionization chamber construction.     

Improved nonlinear optimization in the storage ring of the modern synchrotron radiation light source

In the storage ring of the third generation light sources,nonlinear optimization is an indispensable course in order to obtain ample dynamic acceptances and to reach high injection efficiency and long beam lifetime,especially in a low emittance lattice.An improved optimization algorithm based on the single resonance approach,which takes relative weight and initial Harmonic Sextupole Integral Strength (HSIS) as search variables,is discussed in this paper.Applications of the improved method in several test lattices are presented.Detailed analysis of the storage ring of the Shanghai Synchrotron Radiation Facility (SSRF) is particularly emphasized.Furthermore,cancellation of the driving terms is investigated to reveal the physical mechanism of the harmonic sextupole compensation.Sensitivity to the weight and the initial HSIS as well as dependence of the optimum solution on the convergent factor is analyzed.     

砂墙吸能效应对化爆相似律影响的数值研究

同介质中同能量密度的化学炸药爆炸满足爆炸相似律,在此类化爆实验中,缩比实验作为一种经济有效的实验方法被广泛采用。一些研究人员进行化爆缩比实验时,为了保证实验安全,通常会在实验中加入砂墙,起到吸收爆炸能量,消减冲击波的作用。为了研究砂墙消波吸能效应对化爆相似律的影响,建立了同介质中同能量密度化学炸药爆炸的一维计算模型,并利用两相流程序对三种缩比条件下(1∶1/1∶5/1∶10)的物理模型进行了数值模拟。数值计算结果显示:由于砂墙的吸能效应,化爆不再满足相似律。     

一种突出目标的多光谱遥感信息提取方法

为了突出目标在多光谱遥感图像中的信息,克服由阈值法所带来的人为误差,提出了一种突出遥感目标信息的方法。利用光谱能级匹配法提取目标在图像中的相似度,并将其作为目标信息波段加入到原始数据中去,进行波段归一化处理,以减少不同波段数据的量纲或数量级的影响,进行MNF变换并合成RGB假彩色图像。以新疆哈图地区的重点成矿岩性——凝灰质粉砂岩为例,进行重点目标突出的结果表明,信息增强后的图像颜色更加丰富,与原始假彩色合成图像相比,可以识别出更多的岩石类型,比原始图像的MNF变换划分出更多地物类型。     

基于红外光谱吸收的煤矿瓦斯光纤传感网络

基于气体在其特征吸收波长下光的吸收随浓度变化的原理,通过对甲烷气体红外吸收光谱的分析,设计了一套检测甲烷气体浓度的多点光纤传感网络。该系统采用分布反馈式半导体激光器(DFB LD)作为光源,高灵敏度、低噪声的InGaAs PIN作为光电探测器,结合空分复用技术复用了16个甲烷气体传感器,采用滤波、前置放大等电路对微弱信号进行处理,经PCI数据采集卡采集各路信号后,再用软件编写程序对采集信号进行快速傅里叶变换等分析。研究表明,该网络各传感器的灵敏度均达到200 ppm(μｇ·mL-1),长时间的精确度和稳定性均可满足实际要求,单个传感器的响应时间小于2 s,系统巡检一周的时间小于32 s。通过理论分析得出,该系统各传感器可放置于离地面20公里以上的矿井中,且该系统可在多场合进行多点的实时检测。     

挥发性盐基氮的光谱分析方法

报道了一种挥发性盐基氮(TVB-N)测定方法。通过奈斯勒试剂处理的分子筛吸收挥发性盐基氮,形成NH₂Hg₂IO固相显色体,采用漫反射光谱装置直接测定。探讨了测量原理、条件及影响因素,表明该方法具有操作方便,灵敏度高,试剂用量少等优点。方法的线性范围为1～8 μg·mL-1,检测限达0.1 g·mL-1。用于鱼、肉食品新鲜度的监测,发现鱼肉随放置时间的延长,挥发性盐基氮迅速增加,表明鱼肉的腐败变质是一个加速过程,并且鱼的变质速率相对猪肉更快一些。     

全钒液相储能体系的功率特性研究

研究了全钒功率型液相储能体系惰性电极厚度、活性物质浓度、电解液流量等因素对放电电压和功率密度的影响,以及该液相储能体系的结构和功率特性.在本实验的优化条件下,输出功率密度可达3121W/L.     

离散多层绕带容器在爆炸载荷作用下动力响应的数值模拟研究

运用LS-DYNA3D对不同缠绕角度的离散多层绕带容器在内部中心爆炸载荷作用下的动力响应进行了数值模拟。模拟结果与实验结果、理论分析以及单层圆柱高压容器的动力响应作了比较。研究结果表明,内部中心爆炸载荷作用下,容器绕带层应力分布比较均匀;相同炸药当量条件下,缠绕角度越大,最外层绕带中心的最终位移越大。结果还表明,离散多层绕带容器具有只漏不爆的良好抗爆性能,是单层结构容器不具备的。计算结果可为构建爆炸容器的工程设计标准提供参考。