基于全概率公式直接推求管运洪水

本文为保证防洪安全的前提下充分发挥水库的综合效益,提出了基于全概率公式推求管运洪水的方法,并详细阐述了其基本原理;提出了在资料较短或前、后汛期洪水特性大致相同的情况下运用全概率公式推求管运洪水的实际方法;以马边站的洪水资料进行实例研究,其结果表明基于全概率公式推算出来的管运洪水既能使水库工程达到防洪标准,又能充分发挥水库的综合效益。     

稳定的K-多均值聚类算法

指定K个聚类的多均值聚类算法在K-均值算法的基础上设置了多个次类,以改善K-均值算法在非凸数据集上的劣势,并将多均值聚类问题形式化为优化问题,可以得到更优的聚类效果。但是该算法对初始原型敏感,且随机选取原型的方式使聚类结果不稳定。针对上述问题,提出一种稳定的K-多均值聚类算法,并对该算法的复杂度与收敛性进行了简要讨论。该算法先基于数据样本的最邻近关系构造图,根据图的连通分支将数据分为若干组,取每组数据的均值点作为初始原型,再用交替迭代的方法对优化问题进行求解,得到最后的聚类结果。在人工数据集和真实数据集上的实验表明,该算法具有更稳定更优越的聚类效果。     

荫生植物专类园的规划设计及其探讨

湖南省森林植物园位于长沙市雨花区洞井铺，建 于1985年.在此基础上，1992年又建成了“天际岭国 家森林公园”，隶属湖南省林业厅.全园面积140h扩， 森林覆盖率达90%，林相整齐，植物生长旺盛，森林环 境优美.该园海拔50一106m，属低丘岗地地貌，丘岗 坡度平缓，坡度在20度以下     

330GHz砷化镓单片集成分谐波混频器

在太赫兹频段,二极管尺寸与波长相比已不能忽略,二极管的封装会引入很大的寄生参量,因此需建立二极管三维模型提取寄生参数.同时人工装配难度增大,会增加电路不确定性.采用12μm砷化镓单片集成悬置微带线结构,基于电子科技大学与中国电子科技集团第十三研究所自主联合设计的肖特基二极管研制330 GHz砷化镓单片集成分谐波混频器.实测结果显示在5 mW本振功率的驱动下,在328 GHz可得到最小变频损耗10.4 dB,在320~340 GHz范围内,单边带变频损耗小于14.7 dB.     

A high resolution approach for nonlinear sub-harmonic imaging

Nonlinear sub-harmonic phased array imaging is used to visualize closed cracks. Sub-harmonic imaging has broader beam width than that of input frequency imaging due to its longer wavelength. If the broad beam width results in low image resolution, it can be hard to determine the locations of cracks. Various methods have been developed to enhance the resolution, and MUltiple SIgnal Classification (MUSIC), in particular, is an old but well-established way to do so. A form of sub-harmonic imaging that implements MUSIC is presented here. A numerical simulation was used to compare the proposed method with a conventional one, and MUSIC gave narrower beam width. Experiments also demonstrated that MUSIC could improve the resolution of sub-harmonic imaging.     

太赫兹信号发生与接收技术

论文重点论述了固态太赫兹信号发生和接收技术,太赫兹信号发生采用倍频级联的方案,重点解决了倍频器的 压缩点、驱动功率和倍频效率等三个方面的问题,实现了频率覆盖500GHz 的大功率信号发生。信号接收采用了分谐波 混频的方案,通过构建二极管模型,利用超薄微带电路,实现了混频电路的一体化设计,完成了宽带、低变频损耗的分 谐波混频器,频率覆盖至500GHz。     

一种新型的电流型功率因数校正控制方法

为简化有源功率因数校正的控制策略,提高整机效率,提出了Boost型功率因数校正的一种新的电流型控制方法,其控制结构与线性峰值电流控制、非线性载波控制、预测开关调制的控制结构一样。和传统的峰值控制、平均电流型控制相比,该法无需乘法器、无需检测输入电压、无电流环的稳定性问题,而且通过预测平均电流控制执行不同的开关原理,扩大了连续导电模式的运行范围、没有低频振荡,带两个复位积分器的电路产生预测电流。仿真结果验证了该方法的可行性,能很好地在宽范围输入和负载变化下获得单位功率因数,抗干扰能力强。     

确定化学结构的索引码构造

我们总结了描述确定化学结构的6种属性，并以此设计了一种索引码，用于确定结构的筛选和检索。这种索引码对应于每种属性，形成不同的检索限制条件，可单独使用，也可联合使用，得到一个确定结构候选集，这个集合保证了反继精确匹配所要求的时间、效率和准确性。完成了通过索引码进行检索的单机版和网络版的编程工作并进行了测试。     

Fertilizer requirements for specified yield targets. II. Field verification of mathematical models for the estimation of soil and fertilizer nutrient efficiencies

Sugarcane response data from field experiments conducted between May 1979 and August 1981 on a sandy clay loam soil (Udic Haplustalf) of Coimbatore district, Tamil Nadu State, India were used in the present investigation. Soil () and fertilizer () nutrient efficiencies for the amount of fertilizer required for specified cane yield targets were computed from this data by three procedures, viz., conventional deduction procedure, Tamil Nadu Agricultural University Model I [TNAU Model I] and Model II [TNAU Model II].In the case of nitrogen, both TNAU Model I and TNAU Model II gave more realistic estimates of and than those determined by the conventional deduction procedure. The differences in the predicted amounts of fertilizer nitrogen required between these two models were well within the permissible limits of variation indicating that both these approaches can be followed for the amount of nitrogen required for specified yield targets.The Olsen's procedure for available phosphorus estimation was inadequate to explain the relationship between soil available phosphorus and sugarcane response as indicated by results obtained using the TNAU Model II. The incorporation of the term in this model caters for the actual situation in the field in respect of the relationship between soil and fertilizer phosphorus availabilities and phosphorus uptake by sugarcane proving usefulness of this model for assessing the amount of phosphorus required for specified cane yield targets.The results indicated that a considerable amount of potassium from the soil reserve was released into the soil available pool due to a priming effect. This fraction was preferentially absorbed by sugarcane compared to the fractions extracted by 0.1 N HNO₃ as indicated by results obtained using the TNAU Model II. In this case too, the actual situation regarding the relationship between soil and fertilizer potassium availabilities and potassium uptake by sugarcane is catered for by this model proving its superiority over the other two procedures for assessing the amount of potassium required for specified yield targets.     

0—1多目标规划优化法在矿业投资方向决策中的应用

鉴于矿山采、选、冶联合企业投资方向的决策尚欠科学论证与算法,本文提出按二进制迭加为序的投资状态穷举法,配以严密的0—1多目标规划优化法的数学模型,求解多目标、多属性、多方案、多因素的矿业的投资“瓶颈”问题。借助于计算机,文中给出了理论上和算法上的可行性,提供了开发决策科学化的决策环境。