中国高技术产业投入产出有效性地区差异分析

运用DEA方法,从综合有效性、技术有效性和规模有效性3方面对全国30个省(市、区)(缺失西藏数据)的高技术产业投入产出有效性进行实证分析,根据技术有效性和规模有效性对其发展状态进行分类并提出相应对策。结果表明,我国高技术产业在现有的发展水平上存在投入产出效率不高、总体规模偏大等问题,各省市需针对自身特点制定相应发展策略。     

双差定位法在地震丛集精确定位中的应用

应用双差定位方法(hypodd)对北美Loma Prieta 地区的分属于3个地震丛集的47个地震进行了精确定位.采用交叉谱法精确求取信号的走时差;同时采用人机联做方式在时域调整、修正按自动方式无法准确提取时差的信号,确保每个事件对的走时差精度.重定位后,在几百米的范围内,原来相互重叠的震源位置聚集为三个明显分离的丛集;水平方向的相对位置平均误差为8.5米,震源深度方向的平均误差为23.4 m.     

完全匹配层吸收边界在孔隙介质弹性波模拟中的应用

模拟弹性波在孔隙介质中传播,需要稳定有效的吸收边界来消除或尽可能的减小由人工边界引起的虚假反射. 本文在前人工作基础上,首次建立了弹性孔隙介质情况下完全匹配层吸收边界的高阶速度-应力交错网格有限差分算法,并详细讨论了完全匹配层的构建及其有限差分算法实现. 首先,本文通过均匀孔隙模型的数值解与解析解的对比,验证所提出的数值方法的正确性;然后,本文考察了完全匹配层对不同入射角度入射波和自由表面上的瑞利波的吸收性能,将完全匹配层与廖氏和阻尼吸收边界进行了对比,研究了这三种吸收边界在不同吸收厚度情况下对弹性波吸收能力. 数值结果表明,在孔隙介质中,完全匹配层作为吸收边界能十分有效地吸收衰减外行波,无论对体波还是面波,是一种高效边界吸收算法.     

地球物理学中的电磁场正演与反演

本文在近年来众多的地球物理研究者的研究基础上,总结了当前地电磁模型正反演已有成果,定量分析了各种主要正反演的性能测试,指出不同正反演法的优点、缺点以及应用范围局限,提出了各种方法的发展趋势以及当前计算地球物理领域的核心内容,指出了计算地球物理领域的数值模拟发展方向.     

基于连续帧间差分的抛弃式探头三维下沉运动处理方法研究

抛弃式探头由无人机装载,能够在较远目标区域和危险海域开展海洋水文环境剖面参数的测量。通过安装不同传感器,可以实现对温度、盐度的剖面测量,其深度的测量采用数学方法计算得到。针对双摄像机水箱实验获得的5个不同攻角实验结果,分析了常用的运动目标的检测方法,最终选择基于连续帧间差分法,确定探头的三维坐标位置,进而得到探头下沉运动的三维运动轨迹和速度曲线等信息。探头从水面释放后攻角在下沉过程中不断调整,改变运动姿态,同时伴随自身的旋转,抵消水平方向阻力作用,初始攻角产生的深度测量误差主要体现在加速过程,探头达到匀速运动后测量误差不变,在不考虑横流的情况下,探头最后以匀速垂直下落运动。     

水文重力效应改正中一维地下水模拟算法的对比

基于一维地下水渗透方程详细推导其有限差分解算过程,引入不同于显式差分的隐式差分和中心差分格式,对比分析不同差分格式对地下水模拟结果及其相应地下水重力效应的影响,并对其中的层间参数取值和非线性方程的线性化问题进行探讨。结果表明,在日本Isawa扇形地区超导台站,不同层间参数加权公式能够引起最大约0.15 μGal的重力效应差异,影响在1.9%以内;不同差分格式和线性化方法组合形式能够引起最大约0.12 μGal的重力效应差异,影响在1.5%以内。     

日本囊对虾(Marsupenaeus japonicus)3个野生种群和1个养殖种群的形态差异与判别分析

采用3种多元分析方法,对3个野生种群和1个养殖种群的13个形态比例参数进行比较研究。聚类分析结果表明,广东湛江和海南临高的种群形态最接近,福建厦门种群的趋异程度最大。主成分分析构建了6个主成分,其贡献率分别为:第1主成分23.084%,第2主成分17.976%,第3主成分15.321%,第4主成分13.84%,第5主成分12.707%,第6主成分7.770%,累积贡献率为90.699%。逐步判别选入6个贡献率较大的性状进行判别分析,F检验结果显示,4个种群形态差异显著(P0.01);同时建立了4个种群的判别函数,其判别准确率P1、P2均为100%。综合判别率为100%。3种多元分析结果均认为,4个种群日本囊对虾在形态上已产生一定程度的差异,且集中表现在体重、头胸甲的性状上。     

Compact and tunable mid-infrared source based on a 2 μm dual-wavelength KTiOPO4 intracavity optical parametric oscillator

Using a double resonant KTiOPO₄ (KTP) intracavity optical parametric oscillator operating at degenerated point of 2 μm, we demonstrate a unique mid-infrared source based on difference frequency generation in GaSe crystal. The output tuning range is 8.42-19.52 μm, and a peak power of 834 W for type-I phase matching scheme and 730 W for type-II phase matching scheme are achieved. Experimental results show that this oscillator is a good alternative to the generator of a compact and tabletop mid-infrared radiation with a widely tunable range.     

Computation of wind-wave spectra in coastal waters with SWAN on unstructured grids

An unstructured-grid procedure for SWAN is presented. It is a vertex-based, fully implicit, finite difference method which can accommodate unstructured meshes with a high variability in geographic resolution suitable for representing complicated bottom topography in shallow areas and irregular shoreline. The numerical solution is found by means of a point-to-point multi-directional Gauss–Seidel iteration method requiring a number of sweeps through the grid. The approach is stable for any time step while permitting local mesh refinements in areas of interest. A number of applications are shown to verify the correctness and numerical accuracy of the unstructured version of SWAN.     

Coanda effect in coastal flows

In the present paper some numerical simulations and experiments were carried out to study jet-wall interaction in shallow waters. Namely, modifications of the hydrodynamic field concerning the interaction of river run-off with a shallow coastal water body, due to the presence of marine structures, were investigated. Stratification effects due to salinity and temperature were neglected, and the interest was focused on barotropic features (Coanda effect). The numerical analysis was carried out by means of shallow water equations, numerically solved by finite difference, and the present method was validated by means of a typical simple-shaped test case. The experiments were carried out in a shallow water tank, flow visualizations were performed, and the velocity field was obtained by PIV. The main features of jet-wall interaction flow were investigated in simple-shaped geometries, and applications were shown for two practical cases: Pescara channel harbour (Adriatic Sea, Italy) and the proposed design of Latina harbour (Tyrrhenian Sea, Italy).