tau: A 1D radiative transfer code for transmission spectroscopy of extrasolar planet atmospheres

The tau code is a 1D line-by-line radiative transfer code, which is generally applicable for modeling transmission spectra of close-in extrasolar planets. The inputs are the assumed temperature–pressure profile of the planetary atmosphere, the continuum absorption coefficients and the absorption cross-sections for the trace molecular absorbers present in the model, as well as the fundamental system parameters taken from the published literature. The program then calculates the optical path through the planetary atmosphere of the radiation from the host star, and quantifies the absorption due to the modeled composition in a transmission spectrum of transit depth as a function of wavelength. The code is written in C++, parallelized using OpenMP, and is available for public download and use from http://www.ucl.ac.uk/exoplanets/.     

基于虚拟仪器技术的地下水探测系统研究

为了整合磁共振测深(MRS)地下水探测系统的测量与反演功能,结合LabVIEW软件在测量与信号处理方面的优势,利用虚拟仪器技术开发了地下水探测系统的上位机系统软件,实现了对探测系统整个操作流程的管理。根据已知探测地区的拉莫尔频率产生激发信号,送至发射/接收线圈,利用快速关断技术实现了发射与接收的快速切换。将采集的弛豫衰减信号送至反演解释算法模块,采用改进的量子遗传算法与截断奇异值分解(TSVD)的联合方法,反演解释了地下含水层的水文地质参数。野外试验表明,该探测系统的工作稳定性好,验证了反演结果的准确性。     

洪积扇区域渠系工程设计洪水计算探究——以乌鲁木齐河分洪工程为例

通过对乌鲁木齐河分洪工程渠道沿线洪沟洪水的成因分析,对于山区河沟,采用水文比拟法计算出各河沟出山口处的洪水,对于出山口以下纯坡面区域,采用推理公式法计算其小流域暴雨洪水。根据沿线典型洪沟调查洪峰与推理公式法计算洪峰的拟合情况,率定出计算参数m为Ⅲ类,R=1.1、r1=0.76。对小东沟、乌什城沟出山口断面与渠线断面分别进行洪水调查,可知山区河沟出山口以后每公里河长洪峰衰减率为3.7%~3.9%。利用谷歌卫星地图结合现场调查,将分洪渠道沿线洪沟划分为各个相对独立的区域,对每一个区域分别计算出上游山区衰减至渠线断面的洪水和洪积扇区间洪水后,按照调查洪峰流量的比例将该区域洪峰总量分配到区域内与渠线相交的各个洪沟断面,基于工程安全性考虑,对于有汊流的洪沟,其最终设计洪水成果按加成20%进行处理。     

激光遥感图像高速滤波器算法的FPGA实现

针对激光遥感信号高速高精度的要求,利用FPGA的多任务、高速并行性设计系统进行滤波。考虑到激光光电传感器设计的滤波器会有很大的信号衰减,且具有精度要求高的特点,提出了基于 FPGA内部基本逻辑单元、乘法器、存储器,经过乘法分解和时序设计,实现具有可移植性的图像高速分辨的方法。系统采用FPGA设计平台,并用Verilog语言设计程序。试验结果验证,该滤波器对激光遥感信号具有高速、精确滤波功能,同时表明利用低端FPGA设计激光滤波器必将成为未来发展趋势。     

Transformations of sulphur compounds in high-sulphur coals during reduction in the potassium/liquid ammonia system

The two types of high-sulphur coals Mequinenza and Illinois No. 6, in the initial form and subjected to potassium/liquid ammonia reduction, were analysed by atmospheric pressure-temperature programmed reduction (AP-TPR) method. It has been shown that preliminary demineralisation was beneficial for AP-TPR measurements because of the removal of calcium compounds. The reduction of sulphides and disulphides in the potassium/liquid ammonia system was found to lead to formation of aromatic and aliphatic thiols. The presence of the latter is better manifested in the AP-TPR kinetograms when the measurements are performed in the presence of a special reducing mixture. It has been shown that the coal reduction in the potassium/liquid ammonia system apart from transformations of non-thiophene sulphur groups also leads to breaking up of the C-S bonds in some thiophene systems.     

近地空间通信中的大气闪烁影响分析

利用单艇低仰角低空飞行试验测试数据,验证了Van de Kamp大气闪烁衰减估计模型在低仰角传输链路中的可行性和有效性,并基于该模型和低仰角低空测试数据反演得到近地空间数据估计值,对工作频率、轨道高度以及环境湿度等影响大气闪烁的因素进行计算与仿真,为低仰角近地空间远距离通信的链路预算提供了参考依据。     

基于偶极横波资料的火山岩裂缝及油气识别

火山岩油气藏已成为重要的油气勘探目标和储量增长点.在火山岩的地层评价中,裂缝与油气识别一直是一个核心问题.针对地层矿物成分与岩性十分复杂、常规测井方法很难准确快速识别,应用声波能量衰减对于天然裂缝极为敏感特性,利用斯伦贝谢偶极横波资料可以计算纵、横波及斯通利波能量衰减的特性,实现对裂缝的有效识别.在岩性、物性等因素基本一致的条件下,利用纵、横波能量重叠、泊松比、波速比还可以较好地识别气层.克拉玛依火山岩地层的实际应用效果表明,偶极横波资料在火山岩地层评价中具有十分重要的作用,为火山岩地层裂缝与油气识别开辟了新的途径.     

观测几何对目标探测性能影响的仿真分析

在光电武器作战探测目标性能问题的研究中,不同大气/气溶胶模式、不同观测几何条件下的光电武器作战效能差异显著.针对上述问题,通过分析大气传输和观测几何对视在对比度的影响,建立了视在对比度传递模型,结合TIP准则提出了观测几何对目标探测性能的影响模型.利用Modtran软件离线计算的基础数据,提出了探测性能模型快速仿真计算方法,实现了典型地区、全天时、不同观测几何和观测距离条件下的成像系统探测性能的快速仿真计算.采用快速仿真计算方法,选取典型参数,计算并分析了不同大气/气溶胶模式、观测几何等因素对视在对比度、探测概率和探测距离等指标的影响.结果表明:观测几何对目标探测性能影响显著,50％探测概率条件下,顺光探测距离是逆光探测距离的1.38 ～1.7倍;不同大气/气溶胶模式条件下,观测几何对探测距离影响差异明显,海洋性气溶胶模式下影响较大,乡村型气溶胶模式下影响较小.文中提出了观测几何对目标探测性能的影响模型和快速仿真计算方法,为光电武器系统任务规划和作战效能评估提供了理论和技术支持.     

滩地刚性植物消浪作用特性研究

滩地植物有利于保障沿海地区的水安全,量化成熟期植物消浪作用是提升生态海岸韧性的基础。本文基于一般试验规律和两种波高消减模型,分析提出了新的滩地植物消浪系数计算方法,结合波高条件可计算林带消浪后波高,相关表达式由大量试验数据进行了验证,最后对比了由本文方法与规范方法计算的林带后波高。结果表明,阻尼因数及消浪系数能直观体现植物消浪作用特性,波浪传播方向上植物面积占横截面比例是影响植物消浪机理的关键无量纲参数。植物非淹没时,本文方法得到的林带后波高与规范方法接近;植物淹没时,本文方法能更准确描述植物消浪作用。相较于规范方法,本文方法考虑了植物淹没情况,直观揭示了林带密度、宽度、高度,植物平均直径,水深等参数的影响,适用于更多工况。基于植物消浪作用的模型可快速研判相关参数变化对植物消浪效果的影响,为生态海堤滩地刚性植物规划设计及数模研究提供科学和技术支撑。     

Finite difference method for dynamic response analysis of anchorage system简

Based on some assumptions, the dynamic analysis model of anchorage system is established. The dynamic governing equation is expressed as finite difference format and programmed by using MATLAB language. Compared with theoretical method, the finite difference method has been verified to be feasible by a case study. It is found that under seismic loading, the dynamic response of anchorage system is synchronously fluctuated with the seismic vibration. The change of displacement amplitude of material points is slight, and comparatively speaking, the displacement amplitude of the outside point is a little larger than that of the inside point, which shows amplification effect of surface. While the axial force amplitude transforms considerably from the inside to the outside. It increases first and reaches the peak value in the intersection between the anchoring section and free section, then decreases slowly in the free section. When considering damping effect of anchorage system, the finite difference method can reflect the time attenuation characteristic better, and the calculating result would be safer and more reasonable than the dynamic steady-state theoretical method. What is more, the finite difference method can be applied to the dynamic response analysis of harmonic and seismic random vibration for all kinds of anchor, and hence has a broad application prospect.