检索结果-南通市图书馆

A new parameterization scheme for sea surface aerodynamic roughness

Progress in Natural Science:Materials International 2008年第11期18卷 1365-1373页

作者： Yuping Pan~(a,b) Wenyu Sha~c Shouxian Zhu~c Sufang Ge~(a,*) a nanjing university of Information Science and Technology,nanjing 2.0044,{2. b Air Force Meteorological center of the nanjing Military Region,nanjing 2.0018,{2. c Meteorology College,The PLA university of Information Science and Technology,nanjing 2.1101,{2. nanjing university of Information Science and Technology Nanjing 210044 China Air Force Meteorological center of the nanjing Military Region Nanjing 210018 China Meteorology College The PLA University of Information Science and Technology Nanjing 211101 China

The dimensionless roughness length derived from dimensional analysis bears a relation to wave age,and the dimensionless form of roughness length can be expressed with the relation with a significant wave *** on six experiments(HEXMAX,RASEX,BIO steady platform,Lake Ontario data analysis FETCH,CBLAST low wind),we verified that the Charnock parameter,Zch,and dimension- less roughness length,z0/Hs,are dependent on wave age,u*/***,we constructed a new scheme for roughness length,and explored its sensitivity to friction velocity and wave *** the newly developed parameterization scheme(PS07)with COARE (Coupled Ocean-Atmosphere Response Experiment V.3.0)algorithm,we calculated the data from the North Sea Platform experiment in December,1985,and made an attempt to validate the suitability of the PS07 compared to the other three schemes of *** found that the calculated results based on the PS07 are close to the *** also conducted an experiment in which the PS07 was combined with the nested model of waves coupling in datasets of 3 typhoons that occurred at the Zhanjiang *** comparison results between the calculated and observed waves around the Naozhou Island indicate that the new parameterization scheme(PS07)has a good applicability.

关键词： Sea surface roughness Parameterization scheme Significant wave height Wave age COARE algorithm

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Seabed Classification Using BP Neural Network Based on GA

引用

Acta Oceanologica Sinica 2003年第4期22卷 523-531页

作者： Yang Fanlin1, Liu Jingnan2.1. GPS Engineering Research center, Wuhan university, Wuhan 430079, {2.. 2. Presidential Secretariat, Wuhan university, Wuhan 430079, {2. GPS Engineering Research center Wuhan University Wuhan 430079 China Presidential Secretariat Wuhan University Wuhan 430079 China

Side scan sonar imaging is one of the advanced methods for seabed study. In order to be utilized in other projects, such as ocean engineering, the image needs to be classified according to the distributions of different classes of seabed materials. In this paper, seabed image is classified according to BP neural network, and. Genetic Algorithm is adopted in train network in this paper. The feature vectors are average intensity, six statistics of texture and two dimensions of fractal. It considers not only the spatial correlation between different pixels, but also the terrain coarseness. The texture is denoted by the statistics of the co-occurrence matrix. Double Blanket algorithm is used to calculate dimension. Because a uniform fractal may not be sufficient to describe a seafloor, two dimensions are calculated respectively by the upper blanket and the lower blanket. However, in sonar image, fractal has directivity, i. e. there are different dimensions in different direction. Dimensions are different in acrosstrack and alongtrack, so the average of four directions is used to solve this problem. Finally, the real data verify the algorithm. In this paper, one hidden layer including six nodes is adopted. The BP network is rapidly and accurately convergent through GA. Correct classification rate is 92.5 % in the result.

关键词： BP network co-occurrence matrix fractal classification genetic algorithin

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Large-eddy simulation of formation of three-dimensional aeolian sand ripples in a turbulent field

引用

Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 945-960页

作者： WU ChuiJie1,WANG Ming2.& WANG Liang3 1 State Key Laboratory of Structural analysis for Industrial Equipment,Dalian university of Technology,Dalian 11602.,{2. 2.Yellow River Institute of Hydraulic Research,Zhengzhou 450003,{2. 3 Research center for Fluid Dynamics,Science School,PLA university of Science and Technology,nanjing 2.1101,{2. State Key Laboratory of Structural analysis for Industrial Equipment Dalian University of Technology Dalian China Yellow River Institute of Hydraulic Research Zhengzhou China Research center for Fluid Dynamics Science School PLA University of Science and Technology Nanjing China

With the method of large-eddy simulation,the equation of spherule motion and the method of immersed boundary condition,numerical simulations of three-dimen-sional turbulent aeolian motion and the formation of sand ripples under three-di-mensional turbulent wind and the mutual actions of saltation and creeping motion were carried out. The resulting sand ripples have the form that is flat on the upwind side and steep on the leeward,which is identical to the sand ripples in nature. We also realized the self-restoration process of three-dimensional sand ripples,which shows the correctness of the method of numerical simulation and the models of saltation and creeping. Finally,We analyzed the influence of sand ripples on the three-dimensional turbulent wind field,and found that due to the appearance and development of sand ripples,in the normal direction of ground there exists stronger energy exchange,and moreover,there is close correspondence between the forms of sand ripples and the vorticity close to the ground surface.

关键词： large-eddy simulation equation of spherule motion sand ripples saltation creep

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

IR STUDY ON MONOMOLECULAR PARTICLE AGGLOMERATES OF POLYSTYRENE OBTAINED BY FREEZE-DRYING OF ITS DILUTE SOLUTION

引用

Chinese Journal of Polymer Science 2002年第4期20卷 381-383页

作者： Song Wang Qing-hua Wang Rong-shi Cheng Research center of Materials Beijing Institute of Technology Beijing 100081, china Department of Chemistry{2. nanjing 2.0093. china Research center of Materials Beijing Institute of Technology 北京 100081 Department of Chemistry Nanjing University Nanjing 210093

The monomolecular particle agglomerates of polystyrenes were obtained by freeze-drying of its very dilute solutions of 1.3 x 10(-5)-2.0 x 10(-5) g/mL in benzene:cylcohexane (100:1) solvents, and they were annealed at room temperature for hundred days before use. According to C-13-NMR measurement the polystyrenes should be practically atactic. The number average molecular weights of the samples are 2.80 x 10(3), 2.00 x 10(4), and 1.55 x 10(6), respectively. The freeze-dried aPS with a molecular weight higher than 10(4) show two new IR absorption bands at 1098 and 12.1 cm(-1), which are absent in the normal aPS and freeze-dried styrene oligomer. It was also found that the low molecular weight samples can only form powders, whereas the freeze-dried aPS with higher molecular weight form a mixture of powders and fibrils, of which the longer fibrils show a much stronger 12.1 cm(-1) band than the shorter fibrils and the powder. It seems that the 12.1 cm(-1) band corresponds to the stacking behavior of monomolecular particles.

关键词： monomolecular particles atactic polystyrene FTIR spectroscopy

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Diamond synthesis from a system of chromium-carbide andNi_(70)Mn_(2.)Co_5 alloy

引用

Chinese Science Bulletin 1998年第24期43卷 2063-2066页

作者： LI Liangbin 1, JIANG Jinchun 1, HONG Shiming 1, ZHONG Yumao 2.and ZHANG Xinyuan 2.1. Institute of Applied Physics, Sichuan Union university, Chengdu 610065, china 2. {2. for analysis and Test, Sichuan Union university, Chengdu 610065, china Institute of Applied Physics Sichuan Union University Chengdu China center for analysis and Test Sichuan Union University Chengdu China

In order to ascertain the mechanism of interaction between carbide and metallic catalyst and formation of diamond under high pressure and high temperature, and find a new method to synthesize diamond with special properties, it is necessary to investigate the reaction behavior of different carbides and metallic solvent_catalysts under high pressure and high temperature. A system of Cr-3C-2.powder and Ni 70Mn 2.Co 5 alloy in weight ratio of 1∶6 was treated under 6 0 GPa and 1 500℃ for 2., 30 or 60 min respectively. X_ray diffraction of the samples indicated the Cr 3C 2.decomposed partially after high pressure and temperature treatment, and Cr 7C 3, Cr and diamond formed respectively. There was not any trace of graphite in the samples. The result suggested that the separated carbon atoms could form diamond directly without conversion process of graphite into diamond. The observation of SEI, WDX and EDX also showed that diamond crystals were synthesized in the system, which have perfect surfaces and shapes, with the average grain size of about 40 μm. The properties of the crystals are being investigated.

关键词： chromium_carbide high pressure synthesis diamond.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The correlation of multi-angle thermal infrared data and the choice of optimal view angles

引用

Science china Earth Sciences 2004年第6期47卷 570-576页

作者： FAN Wenjie1 & XU Xiru1,2.1.Institute of Remote Sensing and GIS of Peking university,Beijing 100871,china {2. of Remote Sensing and GIS of Beijing Normal university,Beijing 100875,china Institute of Remote Sensing and GIS of Peking university Beijing China center of Remote Sensing and GIS of Beijing Normal university Beijing China

Based on the matrix formula of thermal infrared radiant system, the components temperature can be retrieved by the inversive matrix. Around the stability problem of retrieved result, the research work we did was focused on (i) the correlation of (wk,j) which is the key to affect the retrieval accuracy, (ii) a general method which can help us find the number of retrievable parameters and evaluate the retrieval error before its performance, (iii) the choice of “optimal viewing angle group” based on the formula of absolute error propagation. The row winter wheat field was chosen as an example. The results can provide a theoretical basis for multi-angle thermal infrared remote sensing and components temperature retrieval.

关键词： components temperature retrieval, correlation, number of retrievable parameters, optimal viewing angle group.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Direct numerical simulation of a supersonic turbulent boundary layer on a flat plate and its analysis

引用

Science china(Physics,Mechanics & Astronomy) 2005年第5期48卷 626-640页

作者： HUANG Zhangfeng1, ZHOU Heng1,2.& LUO Jisheng1,2.1. Department of Mechanics, Tianjin university, Tianjin 300072. china 2. Liu-Hui {2. of Applied Mathematics, Nankai university and Tianjin university, Tianjin 300072. china Department of Mechanics Tianjin University Tianjin China Liu-Hui center of Applied Mathematics Nankai University and Tianjin University Tianjin China

Temporal mode direct numerical simulation (DNS) has been done for a supersonic turbulent boundary layer on a flat plate with Mach number 4.5. It was found that the mean flow profile, the normal-wise distribution of turbulent Mach number and the root mean square (RMS) of the fluctuations of various variables, as well as the Reynolds stresses, bore similarity in nature, when the turbulence reached a fully developed state. But the compressibility effect was strong and must be considered. The strong Reynolds analogy (SRA) and the Morkovin hypothesis were no longer valid. From the end of transition to the fully developed state of turbulence, it was in the transient period, for which the similarity did not hold.

关键词： turbulence, similarity, compressibility effect, supersonic boundary layer, direct numerical simulation.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dynamic equivalent method of interconnected power systems with consideration of motor loads

引用

Science china(Technological Sciences) 2010年第4期53卷 902-908页

作者： ZHOU HaiQiang1,JU Ping1,YANG Hui1 & SUN Ran2.1 Electrical Engineering School,HoHai university,nanjing 2.0098,{2. 2.Henan Power Dispatching & Communication center,Zhengzhou 450052.{2. Electrical Engineering School HoHai University Nanjing China Henan Power Dispatching & Communication center Zhengzhou China

The existing equivalent methods usually only deal with static load models and neglect the dynamic characteristics of loads such as induction *** paper presents a dynamic equivalent method which considers motor *** first,the clustering criterion of motor loads is *** motors with similar dynamic characteristics are classified into one ***,reduction of motors in the same group is carried ***,parameters of the equivalent motor are calculated and the equivalent system is thus *** aggregation method is applied to the New England system of 39-buses and *** results show that the equivalent system retains the dynamic performance of the original system with good *** with the 1-motor equivalent scheme,the 2.motor equivalent scheme can improve equivalent precision effectively.

关键词： power system dynamic equivalent load model induction motor

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Propranolol and verapamil inhibit mRNA expression of RyR2.and SERCA in L-thyroxin-induced rat ventricular hypertrophy

引用

Acta Pharmacologica Sinica 2004年第3期25卷 93-97页

作者： rat ventricular hypertrophy1 Xiao-dong WU2.De-zai DAI2.Qiu-pin ZHANG3,Feng GAO3 Research Division of Pharmacology,china Pharmaceutical university 3Laboratorial {2. ofMedicine,Southeast university,nanjing 2.0009,china Research Division of Pharmacology China Pharmaceutical University Laboratorial center of Medicine Southeast University Nanjing 210009

AIM: To study the alteration in the mRNA level of cardiac ryanodine receptor 2.(RyR2. and sarco-endoplasmic reticulum Ca2.-ATPase (SERCA) in L-thyroxin-induced hypertrophy. METHODS: L-thyroxin (500 g/kg) daily was injected for 10 d. RT-PCR was used to determine mRNA expression. RESULTS: An increase in the relative amount of RyR2.(111 %) and SERCA mRNA (65 %) expression was observed in the hypertrophied rats (RyR2. 77±11; SERCA: 87±10, n=9) compared with the normal rats (RyR2. 36±10; SERCA: 53±10, n=9). Propranolol was effective to inhibit the increase in RyR2.(51±7) and SERCA (63±13) mRNA expression in hypertrophied rats, respectively. Verapamil also reduced RyR2.(62.5) and SERCA (75±8) mRNA expression. CONCLUSION: Both RyR2.and SERCA mRNA level in L-thyroxin-induced cardiac hypertrophy was over-expressed and propranolol or verapamil inhibited the alteration.

关键词： heart hypertrophy arrhythmia ryanodine receptors Ca2.-transporting ATPase L-thyroxin propranolol verapamil reversed transcriptase polymerase chain reaction

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Explanation of the mechanism of carcinogenesis and syntheses of anticancer agents with high selectivity

引用

Science china Chemistry 2006年第1期49卷 44-62页

作者： DAI Qianhuan1,2.1. center of Chemistry and Bioengineering of Cancer Research, Beijing Polytechnic university (Now known as Beijing Univer-sity of Technology), Beijing 10002., {2. 2. center of Environmental Sciences, Peking university, Beijing 100871, {2. center of Chemistry and Bioengineering of Cancer Research Beijing Polytechnic University Beijing China center of Environmental Sciences Peking University Beijing China

In 1979, the mechanism of chemical carcinogenesis, a challenging anddifficult scientific problem pending for a number of years, was explained by Dai Qianhuan. Themechanism named di-region theory predicted that a carcinogen always metabolizes to form a specialbi-functional alky-lating agent. This agent induces cross-linkages between the complementary basepairs in DMA and switches on initial mutageneses in genomes including point and frameshiftmutations. This, in turn, induces further deep mutageneses including the production of variouschimeric chromosomes, deletions and other aberrations found in genomes. In the end this initiatescarcinogenesis of the whole cell through the reverse transcription mechanism after a lengthyincubation period. Recently, this laboratory has verified that physical carcinogenesis, includingthe oncogenesis induced by radiation and asbestos as well as the carcinogenesis induced byendogenous factors such as estrogen or diethyl-stilbestrol switch on carcinogenesis by inducing theformation of cross-linkages between the complementary base pairs in DNA. Di-region theory has nowbeen supported by many experimental observations such as mutational spectra of various *** potential for carcinogenesis, teratogenesis, sterility and mutagenesis lumped together asgenetic toxicity appears to originate almost uniformly from the cross-linking between complementarybases, i.e. malignant cross-linking, which is in accordance with di-region theory. Other forms ofcross-linking between non-complementary bases, benign cross-linkings, show bi-functional alkylationanticancer activity but lack genetic toxicity. The predictable design and synthesis of a highselectivity anticancer agent with high efficacy and low genetic toxicity, a goal long pursued incancer chemotherapy, have been realized for the first time in this laboratory by inhibitingmalignant and heightening benign cross-linking using the principles of di-region theory. A series ofpatented new anticanc

关键词： mechanism of carcinogenesis, di-region theory, minoplatin, selectivity of anticancer agent, cross-linking between DNA bases, anticancer platinum complexes, predictive design of anticancer agent, second generation anticancer agent.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：