喷灌分布均匀系数研究

为突出局部灌溉不足或灌溉过量对均匀性的影响程度,提出了基于几何平均数分布均匀系数的概念,将其定义为部分测点水深几何平均值与所有测点算术平均值的比值。并根据部分测点水深数据的提取方法不同,分为1/4低值、1/4高值、1/2低值和1/2高值分布均匀系数。用MATLAB和VC~++语言编制了可以实现上述分布均匀系数计算的软件"SIUEW1.0"。结果初步证明:基于几何平均数的乘法模型要比基于算术平均数的加法模型更加突出了部分低(或高)于平均值的测点水深数据对均匀系数的影响程度,因此更适用于时局部灌溉不足或过量灌溉有严格控制要求地块的灌溉均匀性评价;无论高值和低值,取点数越少,均匀性的评价结果越差。

高性能InGaAs/AlAs共振隧穿二极管的研制与器件模拟分析

在半绝缘的InP衬底上采用分子束外延的方法生长制备了不同势垒厚度的RTD材料样品,室温下测量的最高峰-谷电流比为18.39.通过模拟得到RTD直流特性与势垒厚度、势阱材料及厚度、隔离层厚度以及掺杂浓度间的关系,对结果进行了分析与讨论.

半导体微碟激光器设计原理与工艺制作

用经典量子电动力学理论初步研究了半导体碟型微腔激光器的设计原理，采用光刻、反应离子刻蚀和选择化学腐蚀等现代微加工技术制备出抽运阈值功率很低且品质因数很高的低温光抽运InGaAs/InGaAsP多量子阱微碟激光器。这种激光器制作工艺简单，对有效光子状态密度调制较大，是比较理想的半导体微腔激光器。

Yellow luminescence mechanism and persistent photoconductivity in n-GaN single crystal films grown on alpha-Al2O3(0001) substrates by LP-MOCVD

Unintentionally doped and Si-doped single crystal n-GaN films have been grown on alpha-Al2O3 (0001) substrates by LP-MOCVD. Room temperature photoluminescence measurement showed that besides the bandedges, the spectrum of an undoped sample was a broad deep-level emission band peaking from 2.19 to 2.30eV, whereas the spectrum for a Si-doped sample was composed of a dominant peak of 2.19eV and a shoulder of 2.32eV. At different temperatures, photoconductance buildup and its decay were also observed for both samples.. The likely origins of persistent photoconductivity and yellow luminescence, which might be associated with deep defects inclusive of either Ga vacancy(V-Ga)/Ga vacancy complex induced by impurities or N antisite (N-Ga), will be proposed.

Photocurrent derivative spectra of ZnCdSe-ZnSe double multi-quantum wells

Photocurrent (PC) spectra of ZnCdSe-ZnSe double multi-quantum wells are measured at different temperature. Its corresponding photocurrent derivative (PCD) spectra are obtained by computing, and the PCD spectra have greatly enhanced the sensitivity of the relative weak PC signals. The polarization dependence of the PC spectra shows that the transitions observed in the PC spectra are heavy-hole related, and the transition energy coincide well with the results obtained by envelope function approximation including strain. The temperature dependence of the photocurrent curves indicates that the thermal activation is the dominant transport mechanism of the carriers in our samples. The concept of saturation temperature region is introduced to explain why the PC spectra have different temperature dependence in the samples with different structure parameters. It is found to be very useful in designing photovoltaic devices.

Early effects of carbon-ion irradiation on murine lymphocytes and thymocytes

To estimate the biological risks from space radiation encountered by cosmonauts in outer space, the effects from whole-body exposure to carbon ions or X-rays irradiations at 0, 0.39, 0.55 and 1 Gy at a dose rate of 0.2 Gy/min were investigated in BALB/c mice. The relative thymus and spleen weights were measured at 24 h after exposure, and the cell cycle distribution and percentage of apoptosis of thymocytes and spleen and peripheral blood lymphocytes were determined by flow cytometry. The data showed that exposure to carbon ions delayed cell progression of peripheral blood lymphocytes in S-phase, and delayed thymocytes and spleen lymphocytes in G(0)/G(1)-phase. Apoptosis of thymocytes and peripheral blood lymphocytes induced by carbon ions increased more rapidly with dose than was the case for X-rays. There were some differences between the relative weight loss of the thymus and the spleen with increasing dose of either carbon ions or X-rays. The results obtained provide evidence of dose- and organ-specific differences induced by carbon ions compared to X-rays, with increased apoptosis in peripheral blood lymphocytes and thymocytes, but not spleen lymphocytes. Our data may suggest that further work would be of interest to estimate risk of changes in immune function during particle radiation exposures in space travel. (c) 2007 COSPAR

CSR实验环高频系统的研制

本文对兰州重离子加速器冷却储存实验环（CSRe）高频系统的研制进行了全面的研究，在首先说明整个冷却储存环物理要求的基础上，提出了CSR实验环对高频系统的物理及参数要求。 CSR实验环高频系统是一套具有较高技术指标和特殊要求的非标复杂设备，除腔体的部分结构以及稳定系统原理参考由近物所与俄罗斯联合设计并由俄罗斯制造的CSR主环高频系统，可以说是国内第一台独立设计、自主研发的重离子同步加速器高频系统，它不仅能在脉冲扫频模式工作，而且能在点频连续波模式工作。论文对CSRe高频同轴谐振腔从理论计算进行了详细的推导，并引入了计算机软件仿真结果对理论推导进行验证，最后在腔体研制加工完成后，将腔体冷态实测结果与理论计算及软件仿真进行了比对，对腔体理论设计的正确性进行了进一步的验证。此外还对整个高频腔体的工艺设计和加工做了较为详细的描述。本文还详细论述了CSRe高频功率源的设计思路与原理，并对整个功率源进行了工程计算与推导，特别针对这种阻抗变化的腔体为负载的功率源的电子管各级工作状态进行了计算与参数选择。最后对四个点频下的高频电压、频率精度和相位失谐量进行了测量，还对特殊的扫频脉冲调制下的电压、相位失谐进行了测量。通过测试结果对系统的设计与研制进行了分析与总结

长白山阔叶红松林冠层空气动力学参数的计算

以大气边界层理论为基础 ,根据高大森林冠层区空气质量守恒原理 ,对长白山天然阔叶红松林冠层空气动力学参数进行了数值计算 .结果表明 ,在不同天气背景下 ,零平面位移和粗糙度长度不是常数 ,但其季节性变化是主要的 .在生长季节零平面位移约为 19～ 2 0m ,粗糙度长度约为 1 2～ 1 3m ,非生长季节零平面位移明显减小 ,只有 14～ 15m ,而粗糙度则明显增加 ,平均达 2m以上 .并讨论了这两个参数在相关研究领域中的应用方法