An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow

The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critica...     

二维递归数字滤波器的稳定性

在本文中,提出了关于二维递归数字滤波器的稳定性检验方法和它的稳定裕量的估算。并给出了数字实例。     

系统平衡裕度分析方法及其应用实例

讨论了裕度概念在科学研究、工程设计、系统运行以及日常生活中的应用情况.分析了裕度概念在各学科间的差别以及其固有的本质内涵,将裕度概念与系统概念、系统平衡概念及平衡临界性相联系,提出了系统平衡域和平衡裕度的新概念并给出了系统平衡域和平衡裕度的定义.在此基础上,提出了对系统平衡域进行分区、按照实际系统裕度值对系统安全性进行评价和监控的理论.以化学反应放热系统为例,给出了利用裕度分析方法对系统进行潜在风险评价的一般思路.     

Discovery of Permian islandarc basalts in the Cenxi area and the tectonic significance

Cenxi Permian basalts are the late Palaeozoic island-arc type basalts first found in South China. REE and trace element characteristics and distribution patterns show that this volcanic formation, which has been isotopically dated at 261 MaB. P. by the³⁹Ar/⁴⁰Ar method, is of an active continental marginal island arc type, and that the tectonic environment at that time was an island-arc marginal sea or minor ocean basin related with the paleo-Tethyan tectonic belt in western Guangdongeastern Guangxi.     

移动无线信道的模拟与应用

介绍一种利用计算机模拟移动无线通信中信道传输特性的方法．该方法主要对瑞利（Ｒａｙｌｅｉｇｈ）和莱斯（Ｒｉｃｅ）分布的非频率选择性衰落信道进行模拟．运用这种方法，研究了相移键控的调制信号（ＢＰＳＫ，ＱＰＳＫ和８ＰＳＫ）在不同莱斯衰落因子信道中的传输特性，分析了莱斯衰落因子和最大多谱勒频移ｆｄ对衰落裕度（ｆａｄｅｍａｒｇｉｎ）和误码限度（ｅｒｒｏｒｆｌｏｏｒ）的影响．对衰落信号的包络和相位以及二进制序列误码率的统计结果表明：模拟特性与理论分析较好地吻合．     

两相流稳定裕度

进行了用相关分析系统辨识方法判别两相流稳定裕度的实验研究。由于采用了该实验方法使两相流动稳定性实验研究方法建立在控制理论基础上，可以在系统正常运行工况下判定两相流稳定裕度及其动态特性，对核供热堆的两相流稳定性预报有实用价值，实验是在核供热堆热工水力学模拟实验系统ＨＲＴＬ－５上进行的，实验结果对两相流动态数学模型的建立与验证提供基础数据。     

企业收益不确定性根源析因

用三种方法分析了企业收益的不确定性,发现影响企业收益不确定性的主要因素是销售量、销售量的标准差、期间成本、单位毛利和债息.在企业盈利时,良好的销售状况、较低的保本销售量和债息可以减少企业收益的不确定性.     

Chronological record of the Early Mesozoic underplating in the northern margin of North China—U-Pb chronometry of zircons in the Late Mesozoic andesite from Western Liaoning

Cathodoluminescence spectroscopic analysis of zircons in the uppermost sanukites of the early Cretaceous Yixian Forma- tion in Western Liaoning reveals zoning structures of the zircons in the volcanic rocks. LA-ICP-MS chronometry shows that the central part of the zircons is remnant zircon with a U-Pb dating of 254 Ma,which is consistent with the age of the Early Mesozoic underplating granulites,and that the periphery is zircon crystallizing out of the host magma with a U-Pb dating of 116 Ma,which is highly consistent with the Ar-Ar dating of the host volcanic rocks.Compositions of the clinopyroxenes xenocrystals in the sanukites are similar to those of the clinopyroxenes in the underplating granulites,indicating that the granulites accreted to the lower crust in the Early Mesozoic have been reformed and disrupted by the upwelling diapers of the asthenosphere and taken part in formation of the sanukites in the Late Mesozoic.     

限制卖空条件下的证券投资组合

 阐述了卖空在证券组合投资策略中的作用,并对实际证券市场中的卖空进行分析.提出了限制性卖空条件下的证券组合投资决策方法,得出较为一般的公式,对几种特殊情形作出分析,并列举实例证明其可行性.     

甘肃白银厂矿田流纹岩的成因及其构造意义

白银厂矿田早-中寒武世流纹岩被认为是大陆裂谷环境或洋内弧岩浆作用的产物。地球化学分析结果显示：流纹岩具有Ti，Nb，Ta明显负异常，Sr和P中等负异常，LREE略富集到富集，相对亏损HFSE，La／Nb值为1～2，La/Th值为1.1～2.5,Th/Ta值高（6～12），部分样品表现为MREE负异常的稀土元素配分特征 ，δu=0.5～1.1,(^87Sr/^86Sr)t=0.7026～0.7048,ENd(t)= 5.60～ 6.14，综合其地球化学特征，推测流纹岩形成应是在大陆地壳基础上，由于与俯冲作用有关的玄武岩浆底侵作用导致镁铁质下地壳发生部分熔融所致。