期刊文献+
任意字段
题名或关键词
题名
关键词
摘要
作者
第一作者
机构
刊名
分类号
参考文献
作者简介
基金资助
栏目信息
共找到487篇文章
< 1 2 … 25 >
每页显示 20 50 100
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
显示方式：
Optimization of beamforming and path planning for UAV-assisted wireless relay networks 认领 引用 被引量：17
1
作者 Ouyang Jian Zhuang Yi +1 位作者 Lin Min Liu Jia 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2014年第2期313-320,共8页
Recently, unmanned aerial vehicles （UAVs） acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifi... Recently, unmanned aerial vehicles （UAVs） acting as relay platforms have attracted considerable attention due to the advantages of extending coverage and improving connectivity for long-range communications. Specifically, in the scenario where the access point （AP） is mobile, a UAV needs to find an efficient path to guarantee the connectivity of the relay link. Motivated by this fact, this paper proposes an optimal design for beamforming （BF） and UAV path planning. First of all, we study a dual-hop amplify-and-forward （AF） wireless relay network, in which a UAV is used as relay between a mobile AP and a fixed base station （BS）. In the network, both of the AP and the BS are equipped with multiple antennas, whereas the UAV has a single antenna. Then, we obtain the output signal^to-noise ratio （SNR） of the dual-hop relay network. Based on the criterion of maximizing the output SNR, we develop an optimal design to obtain the solution of the optimal BF weight vector and the UAV heading angle. Next, we derive the closed-form outage probability （OP） expression to investigate the performance of the dual-hop relay network conveniently. Finally, computer simulations show that the proposed approach can obtain nearly optimal flying path and OP performance, indicating the effectiveness of the proposed algorithm. Furthermore, we find that increasing the antenna number at the BS or the maximal heading angle can significantly improve the performance of the considered relay network. 展开更多
关键词 Aircraft communication Beam forming Path planning Unmanned aerial vehicles Wireless relay networks
暂未订购 下载PDF
On Generality of the Data Plane and Scalability of the Control Plane in Software-Defined Networking 认领 引用 被引量：2
2
作者 ZUO Qingyun CHEN Ming +1 位作者 DING Ke XU Bo 《China Communications》 SCIE CSCD 2014年第2期55-64,共10页
The control and data planes are decoupled in software-defined networking(SDN),which enables both planes to evolve independently,and brings about many advantages such as high flexibility,programmability,and rapid imple... The control and data planes are decoupled in software-defined networking(SDN),which enables both planes to evolve independently,and brings about many advantages such as high flexibility,programmability,and rapid implementation of new network protocols.However,in order to improve the scalability of the control plane at present,some control functionalities are added to the data plane,which is probably to impact on the generality of the data plane.The key challenge of adding control functionalities to the data plane is to strike a careful balance between the generality of the data plane and the scalability of the control plane.We propose some basic principles that both control and data planes should comply with,based on the evolutionary trend of SDN.Moreover,we take two approaches for reference according to the principles,viewed from the control messages in OpenFlow-based SDN.Our evaluations demonstrate that the approaches can maintain the generality of the data plane and improve the scalability of the control plane. 展开更多
关键词 OpenFlow SDN architecture control functionalities control message
暂未订购 下载PDF
PERFORMANCE ANALYSIS AND SIMULATION OF VARIOUS BURST TIME PLAN GENERATION METHODS IN BROADBAND SATELLITE MULTIMEDIA SYSTEM 认领 引用
3
作者 Feng Shaodong Li Guangxia Feng Qi 《Journal of Electronics(China)》 2011年第2期187-197,共11页
The Burst Time Plan(BTP) generation is the key for resource allocation in Broadband Satellite Multimedia(BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused ... The Burst Time Plan(BTP) generation is the key for resource allocation in Broadband Satellite Multimedia(BSM) system.The main purpose of this paper is to minimize the system response time to users' request caused by BTP generation as well as maintain the Quality of Service(QoS) and improve the channel utilization efficiency.Traditionally the BTP is generated periodically in order to simplify the implementation of the resource allocation algorithm.Based on the analysis we find that Periodical BTP Generation(P-BTPG) method cannot guarantee the delay performance,channel utilization efficiency and QoS simultaneously,especially when the capacity requests arrived randomly.The Optimized BTP Generation(O-BTPG) method is given based on the optimal scheduling period and scheduling latency without considering the signaling overhead.Finally,a novel Asynchronous BTP Generation(A-BTPG) method is proposed which is invoked according to users' requests.A BSM system application scenario is simulated.Simulation results show that A-BTPG is a trade-off between the performance and signaling overhead which can improve the system performance insensitive to the traffic pattern.This method can be used in the ATM onboard switching satellite system and further more can be expended to Digital Video Broadcasting-Return Channel Satellite(DVB-RCS) system or IP onboard routing BSM system in the future. 展开更多
关键词 Broadband Satellite Multimedia(BSM) Burst Time Plan(BTP) Resource allocation Multiple access Digital Video Broadcasting-Return Channel via Satellite(DVB-RCS)
暂未订购 下载PDF
Study on Optical Properties of Unpigmented Suspended Particles, Yellow Substance and Phytoplankton Algae in Taihu Lake 认领 引用 被引量：3
4
作者 俞宏 蔡启铭 吴敬禄 《Chinese Journal of Oceanology and Limnology》 2004年第1期24-33,共10页
The optical properties of a waterbody are subjects of research on limnological hydrooptics. The optical properties of, and parameterization methods for, three impurities in Taihu Lake, namely unpigmented suspensions, ... The optical properties of a waterbody are subjects of research on limnological hydrooptics. The optical properties of, and parameterization methods for, three impurities in Taihu Lake, namely unpigmented suspensions, yellow substance and phytoplankton algae, are analyzed in detail in this paper dealing with the optical types of Taihu Lake waters both in winter and in summer. The results showed that: 1) The optical parameters of suspended particles can be calculated by the application of Mie Theory; 2) The absorption of yellow substance decreases exponentially with increasing wavelength, with the mean value of decreasing rate being about 0.014 nm -1; 3) Taihu Lake waters appeared to be of type PY in winter, with suspended particles and yellow substance being the dominant light absorbers, and type CPY in summer, with suspended particles, yellow substance and phytoplankton algae being the dominant light absorbers; 4) In winter or summer, unpigmented suspension has the main effect on the scattering property of Taihu Lake waters. 展开更多
关键词 Taihu Lake unpigmented suspended particles yellow substance phytoplankton algae hydrooptics
暂未订购 下载PDF
ACCURACY OF THE RETRIEVED TEMPERATURE AND HUMIDITY FIELDS FOR TYPHOON HAIYAN UTILIZING THE ADVANCED TECHNOLOGY MICROWAVE SOUNDER 认领 引用 被引量：1
5
作者 盛文杰 刘健文 黄江平 《Journal of Tropical Meteorology》 SCIE 2017年第4期408-416,共9页
One-dimensional retrieval was performed on Typhoon Haiyan utilizing the advanced technology microwave sounder onboard the satellite Suomi NPP to retrieve the temperature and water vapor profiles of the typhoon.Compari... One-dimensional retrieval was performed on Typhoon Haiyan utilizing the advanced technology microwave sounder onboard the satellite Suomi NPP to retrieve the temperature and water vapor profiles of the typhoon.Comparisons of the retrieved profiles and ECMWF reanalysis were made to assess the results. The main conclusions are as follows.(1) The results have high spatial resolution and therefore can precisely represent the temperature and humidity distribution of the typhoon.(2) The retrieved temperature is low in the areas of low temperature and high in the areas of high temperature; similar patterns are observed for humidity. This means that systematic revision may be needed during routine application.(3) The results of the retrieved temperature and humidity profiles are generally accurate, which is quite important for typhoon monitoring. 展开更多
关键词 1-D VAR retrieving algorithm temperature and humidity profiles ATMS NPP Typhoon Haiyan
暂未订购 下载PDF
Impacts of the MJO on Winter Rainfall and Circulation in China 认领 引用 被引量：80
6
作者 贾小龙 陈丽娟 +1 位作者 任福民 李崇银 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2011年第3期521-533,共13页
Impacts of the MJO on winter rainfall and circulation in China are investigated using a real-time multivariate MJO index.Composite results using the daily rainfall anomalies and "rainy day" anomalies accordi... Impacts of the MJO on winter rainfall and circulation in China are investigated using a real-time multivariate MJO index.Composite results using the daily rainfall anomalies and "rainy day" anomalies according to eight different MJO phases show that the MJO has considerable influence on winter rainfall in China. Rainfall anomalies show systematic and substantial changes(enhanced/suppressed) in the Yangtze River Basin and South China with the eastward propagation of the MJO convective center from the Indian Ocean to the western Pacific.When the MJO is in phase 2 and 3(MJO convective center is located over the Indian Ocean),rainfall probability is significantly enhanced.While in phase 6 and 7(MJO convective center is over the western Pacific),rainfall probability is significantly reduced. MJO in winter influences the rainfall in China mainly through modulating the circulation in the subtropics and mid-high latitudes.For the subtropics,MJO influences the northward moisture transport coming from the Bay of Bengal and the South China Sea by modulating the southern trough of the Bay of Bengal and the western Pacific subtropical high.For the mid-high latitudes,the propagation of the low frequency perturbations associated with the eastward-propagating MJO convection modulate the circulation in the mid-high latitudes,e.g.the East Asian winter monsoon and the low trough over central Asia. 展开更多
关键词 MJO rainfall anomaly subtropics mid-high latitudes vertical motion
暂未订购 下载PDF
Effects of process parameters on microstructure and wear resistance of TiN coatings deposited on TC11 titanium alloy by electrospark deposition 认领 引用 被引量：13
7
作者 Xiang HONG Ke FENG +2 位作者 Ye-fa TAN Xiao-long WANG Hua TAN 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第8期1767-1776,共10页
In the present study,the effects of process parameters(output voltage x,nitrogen flux l and specific strengthening time s)on the microstructure and wear resistance properties of TiN coatings prepared by electrospark d... In the present study,the effects of process parameters(output voltage x,nitrogen flux l and specific strengthening time s)on the microstructure and wear resistance properties of TiN coatings prepared by electrospark deposition(ESD)were investigatedsystematically.The microstructure of the coatings was characterized for thickness(TOC),content of TiN(CON)and porosity(POC).A statistical model was developed to identify the significant factors affecting the microstructure and wear resistance of the coatings.The results show that the output voltage x and nitrogen flux l present significant effects on majority of the evaluation indexes such asTOC,friction coefficient(COF)and wear mass loss(Id),while the specific strengthening time s has a significant effect on POC and asmall effect on the other indexes.The optimal process parameters were obtained as follows:output voltage(x,60V),nitrogen flux(l,15L/min)and specific strengthening time(s,3min/cm2).The variation of wear mass loss(Id)by the variation of the outputvoltage(x)and nitrogen flux(l)is attributed to the change of wear mechanisms of TiN coatings.The main wear mechanism of TiNcoating prepared under optimal process parameters is micro-cutting wear accompanied by micro-fracture wear. 展开更多
关键词 electrospark deposition (ESD) TiN coating wear resistance statistical model process parameters
暂未订购 下载PDF
Application of the Tikhonov regularization method to wind retrieval from scatterometer data I.Sensitivity analysis and simulation experiments 认领 引用 被引量：13
8
作者 钟剑 黄思训 +1 位作者 杜华栋 张亮 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第3期274-283,共10页
Scatterometer is an instrument which provides all-day and large-scale wind field information, and its application especially to wind retrieval always attracts meteorologists. Certain reasons cause large direction erro... Scatterometer is an instrument which provides all-day and large-scale wind field information, and its application especially to wind retrieval always attracts meteorologists. Certain reasons cause large direction error, so it is important to find where the error mainly comes. Does it mainly result from the background field, the normalized radar cross-section （NRCS） or the method of wind retrieval？ It is valuable to research. First, depending on SDP2.0, the simulated ＇true＇ NRCS is calculated from the simulated ＇true＇ wind through the geophysical mode] function NSCAT2. The simulated background field is configured by adding a noise to the simulated ＇true＇ wind with the non-divergence constraint. Also, the simulated ＇measured＇ NRCS is formed by adding a noise to the simulated ＇true＇ NRCS. Then, the sensitivity experiments are taken, and the new method of regularization is used to improve the ambiguity removal with simulation experiments. The results show that the accuracy of wind retrieval is more sensitive to the noise in the background than in the measured NRCS; compared with the two-dimensional variational （2DVAR） ambiguity removal method, the accuracy of wind retrieval can be improved with the new method of Tikhonov regularization through choosing an appropriate regularization parameter, especially for the case of large error in the background. The work will provide important information and a new method for the wind retrieval with real data. 展开更多
关键词 scatterometer variational optimization analysis wind retrieval regularization method
暂未订购 下载PDF
On the Differences and Climate Impacts of Early and Late Stratospheric Polar Vortex Breakup 认领 引用 被引量：17
9
作者 李琳 李崇银 +1 位作者 潘静 谭言科 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第5期1119-1128,共10页
The stratospheric polar vortex breakup （SPVB） is an important phenomenon closely related to the seasonal transition of stratospheric circulation. In this paper, 62-year NCEP/NCAR reanalysis data were employed to inv... The stratospheric polar vortex breakup （SPVB） is an important phenomenon closely related to the seasonal transition of stratospheric circulation. In this paper, 62-year NCEP/NCAR reanalysis data were employed to investigate the distinction between early and late SPVB. The results showed that the anomalous circulation signals extending from the stratosphere to the troposphere were reversed before and after early SPVB, while the stratospheric signals were consistent before and after the onset of late SPVB. Arctic Oscillation （AO） evolution during the life cycle of SPVB also demonstrated that the negative AO signal can propagate downward after early SPVB. Such downward AO signals could be identified in both geopotential height and temperature anomalies. After the AO signal reached the lower troposphere, it influenced the Aleutian Low and Siberian High in the troposphere, leading to a weak winter monsoon and large-scale warming at mid latitudes in Asia. Compared to early SPVB, downward propagation was not evident in late SPVB. The high-latitude tropospheric circulation in the Northern Hemisphere was affected by early SPVB, causing it to enter a summer circulation pattern earlier than in late SPVB years. 展开更多
关键词 stratospheric polar vortex breakup （SPVB） stratosphere-troposphere interaction Arctic Os- cillation （AO） season transition
暂未订购 下载PDF
Intelligent Diagnosis of Short Hydraulic Signal Based on Improved EEMD and SVM with Few Low-dimensional Training Samples 认领 引用 被引量：16
10
作者 ZHANG Meijun TANG Jian +1 位作者 ZHANG Xiaoming ZHANG Jiaojiao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2016年第2期396-405,共10页
The high accurate classification ability of an intelligent diagnosis method often needs a large amount of training samples with high-dimensional eigenvectors,however the characteristics of the signal need to be extrac... The high accurate classification ability of an intelligent diagnosis method often needs a large amount of training samples with high-dimensional eigenvectors,however the characteristics of the signal need to be extracted accurately.Although the existing EMD(empirical mode decomposition)and EEMD(ensemble empirical mode decomposition)are suitable for processing non-stationary and non-linear signals,but when a short signal,such as a hydraulic impact signal,is concerned,their decomposition accuracy become very poor.An improve EEMD is proposed specifically for short hydraulic impact signals.The improvements of this new EEMD are mainly reflected in four aspects,including self-adaptive de-noising based on EEMD,signal extension based on SVM(support vector machine),extreme center fitting based on cubic spline interpolation,and pseudo component exclusion based on cross-correlation analysis.After the energy eigenvector is extracted from the result of the improved EEMD,the fault pattern recognition based on SVM with small amount of low-dimensional training samples is studied.At last,the diagnosis ability of improved EEMD+SVM method is compared with the EEMD+SVM and EMD+SVM methods,and its diagnosis accuracy is distinctly higher than the other two methods no matter the dimension of the eigenvectors are low or high.The improved EEMD is very propitious for the decomposition of short signal,such as hydraulic impact signal,and its combination with SVM has high ability for the diagnosis of hydraulic impact faults. 展开更多
关键词 hydraulic impact fault improved EEMD end efect overshoot-undershoot SVM intelligent fault diagnosis short sign al
暂未订购 下载PDF
Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part Ⅰ: Engineering model for the mass loss and nose-blunting of ogive-nosed projectiles 认领 引用 被引量：10
11
作者 Hao Wu Xiao-Wei Chen +1 位作者 Li-Lin He Qin Fang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2014年第6期933-942,共10页
The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the pe... The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator,obviously reducing the penetration efficiency of penetrator.Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface,an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile.A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile.The critical value V c0of the initial striking velocity is formulated,and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V0〉V c0,whilst the mass loss is proportional to the initial kinetic energy of projectile when V0 展开更多
关键词 Projectile High-speed penetration Concrete Mass loss Nose-blunting
暂未订购 下载PDF
PREDICTION OF PROJECTILE PENETRATION AND PERFORATION BY FINITE CAVITY EXPANSION METHOD WITH THE FREE-SURFACE EFFECT 认领 引用 被引量：9
12
作者 Qin Fang Xiangzhen Kong +1 位作者 Jian Hong Hao Wu 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2014年第6期597-611,共15页
With a target treated as the incompressible Tresca and Mohr-Coulomb material, by assuming that cavity expansion produces plastic-elastic and plastic-cracked-elastic response region, the decay function for the free-sur... With a target treated as the incompressible Tresca and Mohr-Coulomb material, by assuming that cavity expansion produces plastic-elastic and plastic-cracked-elastic response region, the decay function for the free-surface effect is constructed for metal and geological tar- gets, respectively. The forcing function for oblique penetration and perforation is obtained by multiplying the forcing function derived on the basis of infinite target assumption with the de- cay function. Then the projectile is modeled with an explicit transient dynamic finite element code and the target is represented by the forcing function as the pressure boundary condition. This methodology eliminates discretizing the target as well as the need for a complex contact algorithm and is implemented in ABAQUS explicit solver via the user subroutine VDLOAD. It is found that the free-surface effect must be considered in terms of the projectile deformation, residual velocity, projectile trajectory, ricochet limits and critical reverse velocity. The numerical predictions are in good agreement with the available experimental data if the free-surface effect is taken into account. 展开更多
关键词 penetration perforation finite spherical cavity expansion free-surface effect
暂未订购 下载PDF
Some new exact solutions of Jacobian elliptic function about the generalized Boussinesq equation and Boussinesq-Burgers equation 认领 引用 被引量：20
13
作者 张亮 张立凤 李崇银 《Chinese Physics B》 SCIE EI CAS 2008年第2期403-410,共8页
By using the modified mapping method, we find some new exact solutions of the generalized Boussinesq equation and the Boussinesq-Burgers equation. The solutions obtained in this paper include Jacobian elliptic functio... By using the modified mapping method, we find some new exact solutions of the generalized Boussinesq equation and the Boussinesq-Burgers equation. The solutions obtained in this paper include Jacobian elliptic function solutions, combined Jacobian elliptic function solutions, soliton solutions, triangular function solutions. 展开更多
关键词 generalized Boussinesq equation Boussinesq-Burgers equation Jacobian elliptic function modified mapping method
暂未订购 下载PDF
Safety risk management of underground engineering in China:Progress, challenges and strategies 认领 引用 被引量：61
14
作者 Qihu Qian Peng Lin 《Journal of Rock Mechanics and Geotechnical Engineering》 CSCD 2016年第4期423-442,共20页
Underground construction in China is featured by large scale, high speed, long construction period,complex operation and frustrating situations regarding project safety. Various accidents have been reported from time ... Underground construction in China is featured by large scale, high speed, long construction period,complex operation and frustrating situations regarding project safety. Various accidents have been reported from time to time, resulting in serious social impact and huge economic loss. This paper presents the main progress in the safety risk management of underground engineering in China over the last decade, i.e.（1） establishment of laws and regulations for safety risk management of underground engineering,（2） implementation of the safety risk management plan,（3） establishment of decision support system for risk management and early-warning based on information technology, and（4） strengthening the study on safety risk management, prediction and prevention. Based on the analysis of the typical accidents in China in the last decade, the new challenges in the safety risk management for underground engineering are identified as follows：（1） control of unsafe human behaviors;（2） technological innovation in safety risk management; and（3） design of safety risk management regulations. Finally, the strategies for safety risk management of underground engineering in China are proposed in six aspects, i.e. the safety risk management system and policy, law, administration, economy, education and technology. 展开更多
关键词 Underground engineering Safety risk management Safety behaviors Safety challenges Safety progress and strategies
暂未订购 下载PDF
Evaluation of Blast-Resistant Performance Predicted by Damaged Plasticity Model for Concrete 认领 引用 被引量：10
15
作者 还毅 方秦 +1 位作者 陈力 张亚栋 《Transactions of Tianjin University》 EI CAS 2008年第6期414-421,共8页
in order to evaluate the capacity of reinforced concrete （RC） structures subjected to blast Ioadings, the damaged plasticity model for concrete was used in the analysis of the dynamic responses of blast-loaded RC st... in order to evaluate the capacity of reinforced concrete （RC） structures subjected to blast Ioadings, the damaged plasticity model for concrete was used in the analysis of the dynamic responses of blast-loaded RC structures, and all three failure modes were numerically simulated by the finite element software ABAQUS. Simulation results agree with the experimental observations. It is demonstrated that the damaged plasticity model for concrete in the finite element software ABAQUS can predict dynamic responses and typical flexure, flexure-shear and direct shear failure modes of the blast-loaded RC structures. 展开更多
关键词 ABAQUS damaged plasticity model for concrete blast loading reinforced concrete structure failure mode
暂未订购 下载PDF
STABILITY ANALYSIS OF TWO-DIMENSIONAL LANDSLIDES SUBJECTED TO SEISMIC LOADS 认领 引用 被引量：6
16
作者 Xiaoping Zhou Qihu Qian +1 位作者 Hao Cheng Haipeng Zhang 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2015年第3期262-276,共15页
In the past, the pseudo-static method used to be the most common for evaluating the stability of landslides under seismic loads, in which static forces acting on the center of gravity of a sliding body are used to con... In the past, the pseudo-static method used to be the most common for evaluating the stability of landslides under seismic loads, in which static forces acting on the center of gravity of a sliding body are used to consider the effects of earthquake. However, seismic loads of rock and soil differ from time and location to time and location. Obviously, it is irrational for the pseudo-static approach to be applied to solving dynamic problems. In this paper, a displacement- pseudo-dynamic model is proposed to assess seismic stability of landslides, in which the sinusoidal- cosinusoidal wave is applied to simulating earthquake displacement, and an ＂amplification factor＂ of peak seismic displacement is referred to as the amplification of seismic wave when it propagates from the bottom to the top of the landslide. The effects of physico-mechanical behaviors of a sliding body on seismic stability of soil slopes are taken into account as well as inertia forces and damping forces. The sensitivity analyses on the permanent displacement and the dynamic factor of safety of landslides are studied in detail. Moreover, a large-scale Tangjiashan landslide that occurred in Wenchuan earthquake is investigated to verify the robustness and precision of the present method. It is found that the results from the present method is in good agreement with those from the previous method. 展开更多
关键词 pseudo-dynamic factor of safety slices method inertia force damping force sliding displacement displacement-pseudo-dynamic model two-dimensional landslides seismic loads
暂未订购 下载PDF
A Numerical Study of the Interaction between Two Simultaneous Storms:Goni and Morakot in September 2009 认领 引用 被引量：7
17
作者 吴限 费建芳 +3 位作者 黄小刚 张翔 程小平 任建奇 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2012年第3期561-574,共14页
Significant anomalous tracks were observed when the severe tropical storm Goni （0907） and typhoon Morakot （0908） in September 2009 were evaluated in short distances. The relationship between the two is regarded as... Significant anomalous tracks were observed when the severe tropical storm Goni （0907） and typhoon Morakot （0908） in September 2009 were evaluated in short distances. The relationship between the two is regarded as a case of binary interaction. Based on an MM5 model （fifth=generation mesoscale model of Pennsylvania State University-National Center for Atmospheric Research）, in this study a series of sensitivity experiments were designed to determine the binary interaction between them. The sensitivity of the storm characteristics to the binary interaction was demonstrated through modeling experiments with different TC intensities and sizes based on the bogus vortices initialization. Furthermore, the contributions of large-scale environmental flow and the effects of interaction between the motions of the cyclones were distinguished by numerical experiments using only one of the TC vortices. Results from these experiments show that Morakot （0908） had a greater impact on the motion of Goni （0907）, whereas Goni （0907） had a relatively limited impact on Morakot （0908）. At the upper level, the northeasterly jet flow in the third quadrant of Morakot （0908） enhanced the upper-level divergence of Goni （0907） and had an important role in maintaining and increasing Goni＇s （0907） intensity. And at the lower level, Morakot （0908）, with strong convergence and ascending airflow, made a stable transport channel of southwesterly warm and wet flow, thus supporting the lower-level water vapor convergence of Goni （0907）. Goni （0907）, which was located upriver of the southwesterly flow, intercepted part of the water vapor transportation in the southwesterly flow, causing the water vapor convergence to strengthen while the water vapor convergence of Morakot （0908） weakened. 展开更多
关键词 binary tropical cyclones interaction numerical experiments
暂未订购 下载PDF
A New Hybrid Vertical Coordinate Ocean Model and Its Application in the Simulation of the Changjiang Diluted Water 认领 引用 被引量：8
18
作者 张文静 朱首贤 +1 位作者 董礼先 张长宽 《China Ocean Engineering》 SCIE EI 2011年第2期327-338,共12页
Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ co... Based on the analysis of the advantages and disadvantages of some vertical coordinates applied in the calculation of the Changjiang diluted water （CDW）, a new hybrid vertical coordinate is designed, which uses σ coordinate for current and σ-z coordinate for salinity. To combine the current and salinity, the Eulerian-Lagrangian method is used for the salinity calculation, and the baroclinic pressure gradient （BPG） is calculated on the salinity sited layers. The new hybrid vertical coordinate is introduced to the widely used model of POM （Princeton Ocean Model） to make a new model of POM-σ-z. The BPG calculations of an ideal case show that POM-σ-z model brings smaller error than POM model does. The simulations of CDW also show that POM-σ-z model is better than POM model on simulating the salinity and its front. 展开更多
关键词 hybrid vertical coordinate baroclinic pressure gradient Eulerian-Lagrangian method the Changjiang diluted water numerical simulation
暂未订购 下载PDF
Semi-theoretical analyses of the concrete plate perforated by a rigid projectile 认领 引用 被引量：5
19
作者 Hao Wu Qin Fang +1 位作者 Ya-Dong Zhang Zi-Ming Gong 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2012年第6期1630-1643,共14页
Based on the three-stage perforation model, a semi-theoretical analysis is conducted for the ballistic per- formances of a rigid kinetic projectile impacting on concrete plates. By introducing the projectile resistanc... Based on the three-stage perforation model, a semi-theoretical analysis is conducted for the ballistic per- formances of a rigid kinetic projectile impacting on concrete plates. By introducing the projectile resistance coefficients, dimensionless formulae are proposed for depth of penetra- tion （DOP）, perforation limit thickness, ballistic limit veloc- ity, residual velocity and perforation ratio, with the projec- tile nosed geometries and projectile-target interfacial fric- tion taken into account. Based on the proposed formula for DOP and lots of penetration tests data of normal and high strength concrete targets, a new expression is obtained for target strength parameter. By comparisons between the re- sults of the proposed formulae and existing empirical formu- lae and large amount of projectile penetration or perforation tests data for monolithic and segmented concrete targets, the validations of the proposed formulae are verified. It is found that the projectile-target interfacial friction can be neglected in the predictions of characteristic ballistic parameters. The dimensionless DOP for low-to-mid speed impacts of non-flat nosed projectiles increases almost linearly with the impact factor by a coefficient of 2/（nS）. The anti-perforation ability of the multilayered concrete plates is dependent on both the target plate thickness and the projectile impact velocity. The variation range of the perforation ratio is 1-3.5 for concrete targets. 展开更多
关键词 Projectile Concrete Depth of penetration Perforation limit thickness Ballistic limit velocity Resid-ual velocity
暂未订购 下载PDF
Dynamic strength of rocks and physical nature of rock strength 认领 引用 被引量：14
20
作者 Qihu Qian Chengzhi Qi Mingyang Wang 《Journal of Rock Mechanics and Geotechnical Engineering》 2009年第1期1-10,共10页
Time-dependence of rock deformation and fracturing is often ignored.However,the consideration of the time-dependence is essential to the study of the deformation and fracturing processes of materials,especially for th... Time-dependence of rock deformation and fracturing is often ignored.However,the consideration of the time-dependence is essential to the study of the deformation and fracturing processes of materials,especially for those subject to strong dynamic loadings.In this paper,we investigate the deformation and fracturing of rocks,its physical origin at the microscopic scale,as well as the mechanisms of the time-dependence of rock strength.Using the thermo-activated and macro-viscous mechanisms,we explained the sensitivity of rock strength to strain rate.These mechanisms dominate the rock strength in different ranges of strain rates.It is also shown that a strain-rate dependent Mohr-Coulomb-type constitutive relationship can be used to describe the influence of strain rate on dynamic rock fragmentation.A relationship between the particle sizes of fractured rocks and the strain rate is also proposed.Several time-dependent fracture criteria are discussed,and their intrinsic relations are discussed.Finally,the application of dynamic strength theories is discussed. 展开更多
关键词 rock dynamics deformation and fracturing time-dependence dynamic strength criteria of fracturing
暂未订购 下载PDF
已选0条
引用分析
参考文献
引证文献
 统计分析
检索结果
已选文献
上一页 1 2 … 25 下一页 到第 页
在线咨询 使用帮助 返回顶部 意见反馈