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Automatic image enhancement by learning adaptive patch selection
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作者 Na LI Jian ZHANG 《信息与电子工程前沿:英文版》 SCIE EI CSCD 2019年第2期206-221,共16页
Today, digital cameras are widely used in taking photos. However, some photos lack detail and need enhancement. Many existing image enhancement algorithms are patch based and the patch size is always fixed throughout ... Today, digital cameras are widely used in taking photos. However, some photos lack detail and need enhancement. Many existing image enhancement algorithms are patch based and the patch size is always fixed throughout the image. Users must tune the patch size to obtain the appropriate enhancement. In this study,we propose an automatic image enhancement method based on adaptive patch selection using both dark and bright channels. The double channels enhance images with various exposure problems. The patch size used for channel extraction is selected automatically by thresholding a contrast feature, which is learned systematically from a set of natural images crawled from the web. Our proposed method can automatically enhance foggy or under-exposed/backlit images without any user interaction. Experimental results demonstrate that our method can provide a significant improvement in existing patch-based image enhancement algorithms. 展开更多
关键词 Image ENHANCEMENT Contrast ENHANCEMENT DARK CHANNEL BRIGHT CHANNEL ADAPTIVE PATCH based processing
“通实力”与“一带一路”通道建设研究 预览
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作者 李振福 《学术探索》 2019年第9期34-43,共10页
"一带一路"倡议提出以来,在习近平新时代中国特色社会主义思想的理论指导下,从顶层设计到逐步落地实施,正在有序展开。为此,提出"通实力"理论,认为"通实力"是国家综合利用所掌控的自身与外部的资源和能力... "一带一路"倡议提出以来,在习近平新时代中国特色社会主义思想的理论指导下,从顶层设计到逐步落地实施,正在有序展开。为此,提出"通实力"理论,认为"通实力"是国家综合利用所掌控的自身与外部的资源和能力,促进国家内部、国家与世界其他国家间以及世界各国家地区间在政治、经济、文化等领域的沟通、交互、理解,进而构建形成以"通"为基础机制的大系统范围的共同体。在此基础上,对目前"一带一路"通道建设的现状和存在的问题进行系统分析,并依据"通实力"理论,提出了具体的"一带一路"通道建设策略建议。 展开更多
关键词 “一带一路” “通实力” 通道 通道建设
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Vehicle-to-Infrastructure Channel Characterization in Urban Environment at 28 GHz 预览
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作者 Longhe Wang Bo Ai +4 位作者 Danping He Ke Guan Jiayi Zhang Junhyeong Kim Zhangdui Zhong 《中国通信:英文版》 SCIE CSCD 2019年第2期36-48,共13页
Both ultra-reliable low latency and high-data-rate communications are required by connective vehicles.Millimeter wave(mmWave)with large bandwidth is a key technology to support high-data-rate communications.In this pa... Both ultra-reliable low latency and high-data-rate communications are required by connective vehicles.Millimeter wave(mmWave)with large bandwidth is a key technology to support high-data-rate communications.In this paper,the 28 GHz wideband vehicle-to-infrastructure channel is characterized for the urban environment in a major street in Manhattan.The deployment of the transmitter and the receiver,as well as the traffic models,are selected by considering the recommendation by 3GPP TR 37.885.Ray tracing simulator with calibrated electromagnetic parameters is employed in this work to practically conduct intensive simulations.The 3D environment model is reconstructed from OpenStreetMap.The power delay profile,path loss,root-meansquare delay spread,K-factor and so on,are extracted from the calibrated simulation results.The evolution of the parameters,as well as their statistical properties,are analyzed and modeled.The work of this paper helps the researchers understand the propagation channel for designing mmWave technologies and communication system in a similar scenario. 展开更多
关键词 CHANNEL characterization mmWave CHANNEL RAY TRACING URBAN environment vehicular communication
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Neural Network and GBSM Based Time-Varying and Stochastic Channel Modeling for 5G Millimeter Wave Communications 预览
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作者 Xiongwen Zhao Fei Du +4 位作者 Suiyan Geng Ningyao Sun Yu Zhang Zihao Fu Guangjian Wang 《中国通信:英文版》 SCIE CSCD 2019年第6期80-90,共11页
In this work,a frame work for time-varying channel modeling and simulation is proposed by using neural network(NN)to overcome the shortcomings in geometry based stochastic model(GBSM)and simulation approach.Two NN mod... In this work,a frame work for time-varying channel modeling and simulation is proposed by using neural network(NN)to overcome the shortcomings in geometry based stochastic model(GBSM)and simulation approach.Two NN models are developed for modeling of path loss together with shadow fading(SF)and joint small scale channel parameters.The NN models can predict path loss plus SF and small scale channel parameters accurately compared with measurement at 26 GHz performed in an outdoor microcell.The time-varying path loss and small scale channel parameters generated by the NN models are proposed to replace the empirical path loss and channel parameter random numbers in GBSM-based framework to playback the measured channel and match with its environment.Moreover,the sparse feature of clusters,delay and angular spread,channel capacity are investigated by a virtual array measurement at 28 GHz in a large waiting hall. 展开更多
关键词 TIME-VARYING CHANNEL NEURAL network CLUSTER CHANNEL modeling VIRTUAL array measurement 5G
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大规模MIMO阵列结构对信道容量的影响——二维与三维的对比分析 预览
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作者 王绍宇 毕治宇 孙珊 《科技视界》 2019年第12期6-7,24共3页
本文针对相同天线数目下,二维方形阵和三维立方体阵的信道容量对比。通过推导两种阵列的方向矩阵和角度功率谱,得到信道矩阵,从而求解信道容量。仿真结果表明:相同条件下,三维阵列的信道容量远高于二维阵列。
关键词 大规模MIMO阵列 信道 角度功率谱 信道容量
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HFC网络宽带故障解决方法研究 预览
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作者 张彬 樊元坝 《天津科技》 2019年第7期9-12,共4页
有线宽带的接入系统是基于DOCSIS标准来设计的,系统主要由前端设备CMTS和Cable Modem组成。Cable Modem接入的物理基础是广电传统的双向HFC网络,CMTS作为前端路由器、交换集线器与CATV网络之间的连接设备,对终端设备进行CM认证、配置和... 有线宽带的接入系统是基于DOCSIS标准来设计的,系统主要由前端设备CMTS和Cable Modem组成。Cable Modem接入的物理基础是广电传统的双向HFC网络,CMTS作为前端路由器、交换集线器与CATV网络之间的连接设备,对终端设备进行CM认证、配置和管理,同时提供CM链接IP骨干网和Internet的通道。 展开更多
关键词 噪声干扰 调制方式 消波 信道 信道绑定
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Analysis of the Spectral Characteristics of Triggered Lightning 预览
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作者 Huaming ZHANG Yijun ZHANG +3 位作者 Weitao LYU Yang ZHANG Qi QI Yanfeng FAN 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第11期1265-1272,共8页
The spectra with wavelength range of 390 nm to 660 nm of triggered lightning were observed in Guangdong Area using a slitless spectrograph. The characteristics of the lightning spectra during the initial continuous cu... The spectra with wavelength range of 390 nm to 660 nm of triggered lightning were observed in Guangdong Area using a slitless spectrograph. The characteristics of the lightning spectra during the initial continuous current and return strokes were analyzed, and the differences between the metal section and air section of the lightning channel were compared. The results showed that the metal spectra were contained in the metal section during the initial continuous current. As for the lightning channel of the return strokes, the line spectra for both the metal section and the air section were identical;neither of the two sections contained the metal spectra, but the relative intensity of its emission spectrum was different. Owing to different radiation mechanisms, the spectral structures and luminance of the two sections were not the same. Combined with the current data, it was found that there was a good positive correlation between the total spectral strength and the transferred charge. The total intensity of the lightning channel spectrum increased with the height of the channel, indicating that the radiation sequence of the lightning channel was different. High temporal resolution observations showed that the spectral line duration could be divided into three categories, in which the lines with higher excitation energy appear first and decay rapidly, while those with lower excitation energy appear later but last longer. 展开更多
关键词 triggered LIGHTNING LIGHTNING SPECTRA METAL CHANNEL AIR CHANNEL CURRENT
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Thermal-Hydraulic-Structural Analysis and Design Optimization for Micron-Sized Printed Circuit Heat Exchanger
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作者 HOU Yaqiong TANG Guihua 《热科学学报:英文版》 SCIE EI CAS CSCD 2019年第2期252-261,共10页
The Printed Circuit Heat Exchanger(PCHE) is one of the most promising heat exchangers for Synergetic Air-breathing and Rocket Engine(SABRE). To reduce pressure drop and improve compactness, the micron-sized PCHE made ... The Printed Circuit Heat Exchanger(PCHE) is one of the most promising heat exchangers for Synergetic Air-breathing and Rocket Engine(SABRE). To reduce pressure drop and improve compactness, the micron-sized PCHE made up of rectangular channels of tens of microns in size, is used in SABRE. In present work, we focus on thermal-hydraulic-structural characteristics of micron-sized PCHE by conducting three-dimensional(3-D) numerical simulation. Helium and hydrogen are employed as the working fluids and the Stainless Steel 316(SS316) as the solid substrate. The thermal-hydraulic performance of the micron-sized PCHE is discussed by using the commercial Computational Fluid Dynamics(CFD) software of Fluent. ANSYSMechanical is also employed to simulate stress field of representative PCHE channels. The mechanical stress induced by pressure loading and the thermal stress induced by temperature gradient are found to be equally important sources of stress. To improve comprehensive performances of micron-sized PCHE, two types of channel arrangements and different channel aspect ratios are studied. The double banking is of higher thermal-hydraulic performance compared to the single banking while the stress performance is identical for the two modes. Meanwhile, the effect of channel aspect ratio is investigated by comparing thermal-hydraulic characteristics and structural stress of the model. The rectangular channel with w/h=2 achieves the most balanced stress characteristic and higher thermal-hydraulic performance. 展开更多
关键词 computational fluid dynamics(CFD) Printed Circuit Heat EXCHANGER thermal-hydraulic-structural performance CHANNEL arrangement CHANNEL aspect ratio
Hot Air Generator Using Natural Convection Flow in a Heated Channel 预览
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作者 Bushra AlGarawi Zeinebou Yahya 《能源与动力工程:英文版》 2019年第4期131-136,共6页
Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impedin... Hot air producing is one of the most important engineering applications in recent years.It is a technique used in various thermodynamic systems,such as home heating systems,food dryers.One of the main problems impeding the spread of hot air producing technology is the lack of homogeneity of the heat flow coming from hot air generators as well as an inadequate flow rate.The most of the existing hot air generators require to be supported by systems that can increase the low volumetric flow and the air temperature of these generators,through increasing the speed of the flow of air emitted or lifting the drawer Heat,which contributes to raising the overall cost.However,to improve the thermal and dynamic quality of the hot air flow produced by the generator,a numerical investigation of the free convection flow inside two different configurations is presented in this thesis.The primary objective of this work is to predict the behavior of the flow inside tow configurations,the first one consists of a vertical cylinder with heated walls,and the second configuration is an open-ended vertical cylinder with a hot disc placed at the entrance(configuration A,configuration B).This work characterizes through the examination of this flow,the variables that control an air emission with high flow rate and a high and homogeneous temperature to represent the appropriate criteria that should be respected to obtain a hot air generator overcoming the previously mentioned constraints.Furthermore;the results of this work show the influence the boundary conditions and Rayleigh number on the resulting flow. 展开更多
关键词 Hot air GENERATOR NATURAL CONVECTION vertical CHANNEL NAVIER-STOKES equations finite volume method
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3’-Methoxydaidzein exerts analgesic activity by inhibiting voltage-gated sodium channels
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作者 XU Run-Jia FEI Shuo-Han +6 位作者 CHEN Lin-Yan WANG Gan LIU Ming ZHANG Wen-Sheng YAN Xiu-Wen LAI Ren SHEN Chuan-Bin 《中国天然药物:英文版》 SCIE CAS CSCD 2019年第6期413-423,共11页
Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but... Isoflavones are widely consumed by people around the world in the form of soy products, dietary supplements and drugs. Many isoflavones or related crude extracts have been reported to exert pain-relief activities, but the mechanism remains unclear. Voltage-gated sodium channels(VGSCs) play important roles in excitability of pain sensing neurons and many of them are important nociceptors. Here, we report that several isoflavones including 3’-methoxydaidzein(3 MOD), genistein(GEN) and daidzein(DAI) show abilities to block VGSCs and thus to attenuate chemicals and heat induced acute pain or chronic constriction injury(CCI) induced pain hypersensitivity in mice. Especially, 3 MOD shows strong analgesic potential without inducing addiction through inhibiting subtypes NaV1.7, NaV1.8 and NaV1.3 with the IC50 of 181 ± 14, 397 ± 26, and 505 ± 46 nmol·L–1, respectively, providing a promising compound or parent structure for the treatment of pain pathologies. This study reveals a pain-alleviating mechanism of dietary isoflavones and may provide a convenient avenue to alleviate pain. 展开更多
关键词 3’-Methoxydaidzein ANALGESIC ISOFLAVONE CHRONIC PAIN SODIUM channel
Experimental study on the flow pattern and pressure gradient of air-water two-phase flow in a horizontal circular mini-channel 预览
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作者 Sudaija Aqli Haq +2 位作者 Deendarlianto Indarto Adhika Widyaparaga 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期102-116,共15页
Experimental studies on the flow pattern and the pressure gradient of gas-liquid co-current two-phase flow in a mini-channel were conducted.The test section was a transparent circular channel of 1.6 mm inner diameter.... Experimental studies on the flow pattern and the pressure gradient of gas-liquid co-current two-phase flow in a mini-channel were conducted.The test section was a transparent circular channel of 1.6 mm inner diameter.The working fluids were air and water.The superficial velocities of gas and liquid were in the range of 0.025-66.300 m/s and 0.033-4.935 m/s,respectively.In the present work,the flow pattern and the pressure gradient data were obtained by analyzing the flow images captured by a high-speed camera,and by using the pressure transducer,respectively.As a result,it was found that (1) the obtained flow patterns were bubbly,plug,slug-annular,annular,and chum flows,(2) new experimental correlations on the bubble and plug lengths were proposed,whereas the lengths are the function of the homogeneous void fraction,(3) both gas and liquid superficial velocities affect proportionally to the pressure gradient,whereas it increases with the increase both of JG,JL.In addition,the obtained flow patterns are in a good agreement with that of the available flow pattern maps in the open literatures,such as,Triplett et al.(1999) and Chung and Kawaji (2004). 展开更多
关键词 TWO-PHASE FLOW mini channel FLOW pattern pressure GRADIENT plug length
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Preparation of Al-Zn-Mg-Cu alloy semisolid slurry through a water-cooled serpentine pouring channel
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作者 Wen-zhi Zhu Wei-min Mao +2 位作者 Qing-song Wei Chen Hui Yu-sheng Shi 《中国铸造:英文版》 SCIE 2019年第1期31-39,共9页
The semisolid slurry of Al-Zn-Mg-Cu alloy was prepared through a self-designed water-cooled copper serpentine pouring channel(WSPC) machine. Influences of pouring temperature, the number of turns and the cooling water... The semisolid slurry of Al-Zn-Mg-Cu alloy was prepared through a self-designed water-cooled copper serpentine pouring channel(WSPC) machine. Influences of pouring temperature, the number of turns and the cooling water flow rate on the microstructure of the semisolid Al-Zn-Mg-Cu alloy slurry were investigated. The results show that the semisolid Al-Zn-Mg-Cu alloy slurry with satisfactory quality can be generated by the WSPC when the pouring temperature is in the range between 680 ℃ and 700 ℃. At a given pouring temperature, the average grain size of primary α-Al decreases and the shape factor increases with the increase of the number of turns. When the cooling water flow rate is 450 L·h-1, the obtained semisolid slurry is optimal. During the preparation of the semisolid Al-Zn-Mg-Cu alloy slurry with low superheat pouring, the alloy melt has mixed inhibition and convection flow characteristics by 'self-stirring'. When the alloy melt flows through the serpentine channel, the chilling effect of the inner wall of the channel, the convection and mixed inhibition of the alloy melt greatly promote the heterogeneous nucleation and grain segregation. This effect destroys the dendrite growth mode under traditional solidification conditions, and the primary nuclei gradually evolve into spherical or nearspherical grains. 展开更多
关键词 Al-Zn-Mg-Cu Alloy SEMISOLID slurry WATER-COOLED SERPENTINE CHANNEL primary α-Al
Sedimentary characteristics comparison and genesis analysis of the deepwater channel in the hydrate enrichment zones on the north slope of the South China Sea 预览
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作者 Chao Fu Xinghe Yu +3 位作者 Yiis Dong Yulin He Jinqiang Liang Zenggui Kuang 《海洋学报:英文版》 SCIE CAS CSCD 2019年第3期103-113,共11页
Natural gas hydrate(NGH) is one of the important clean energy at present and even in the future. The study of its sedimentary environment and minerogenetic condition has long been a hot issue that has received much co... Natural gas hydrate(NGH) is one of the important clean energy at present and even in the future. The study of its sedimentary environment and minerogenetic condition has long been a hot issue that has received much concern from geologists all over the world. China has successfully obtained the samples of NGH in Shenhu and Dongsha sea areas in 2007, 2013 and 2015, respectively. From this, the continental slope north of the South China Sea becomes an important test site for the study of NGH sedimentary genesis and minerogenetic condition. NGH has been found in Shenhu, Dongsha and Qiongdongnan areas within the continental slope north of South China Sea,at different depths of water, with different sedimentary characteristics, gas genesis, and minerogenetic conditions.Using a seismic sedimentology theory, combining seismic facies results of each facies, sedimentary facies and evolution of each area are documented in turn establishing a sedimentary model by considering palaeogeomorphology, sea level change and tectonic movement. The channel system and MTD(Mass Transport Deposition) system among these three areas were compared focusing on the developing position, appearance and controlling factors. Relative location among three areas is firstly defined that Dongsha area in a nearprovenance steep upper slope, Shenhu area in a normal gentle slope and Qiongdongnan area in an awayprovenance flat plain. Besides, their channel systems are classified into erosional, erosional-aggradational and aggradational channel, and MTD systems into headwall domain, translational domain and toe domain. 展开更多
关键词 sedimentary characteristics DEEP-SEA channel GENESIS COMPARISON HYDRATE ENRICHMENT ZONES
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The barrier river reach identification and classification in the Middle Yangtze River
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作者 Jinwu TANG Chunyan HU +4 位作者 Xingying YOU Yunping YANG Xiaofeng ZHANG Jinyun DENG Meng CHEN 《地球科学前沿:英文版》 CSCD 2019年第3期596-613,共18页
Adjustments of upstream river regimes are one of the main factors affecting downstream fluvial processes. However, not all adjustments of river regimes will propagate downstream. There are some distinctive river reach... Adjustments of upstream river regimes are one of the main factors affecting downstream fluvial processes. However, not all adjustments of river regimes will propagate downstream. There are some distinctive river reaches where upstream and downstream adjustments have no relevance. However, the irrelevance is neither caused by different river types nor by the different conditions of water and sediment;but rather, the channel boundaries and riverbed morphologies block the propagation effect. These are referred to here as the barrier river reach phenomena. The migration of the thalweg line is the essential reason for causing the propagation effect. Numerous influencing factors for thalweg migration exist, including 1) the average flow rate above the critical bankfull discharge, the average flow rate below the critical bankfull discharge, and their ratio, 2) the ratio of the duration of the aforementioned two periods, 3) the thalweg displacement at the entrance of the river reach, 4) the deflecting flow intensity of the node, 5) the ratio of the river width to water depth, 6) the relative width of the floodplain, and 7) the Shields number. In this study, the correlativity between the measured distances and the restricting indicators of thalweg migration in the Middle Yangtze River over the years was established. The barrier degree of 27 singlethread river reaches was subsequently assessed. These reaches included 4 barrier river reaches;5 transitional reaches transforming from barrier to non-barrier;10 transitional reaches transforming from non-barrier to barrier;and 8 non-barrier river reaches. Barrier river reaches were found to be important for maintaining the stability of the river regime and the transverse equilibrium of sediment transport in the downstream reaches. To some extent, the barrier river reaches may protect the natural dynamical properties from being destroyed by artificial river regulation works. Thus, they are of great significance for river management. 展开更多
关键词 the BARRIER RIVER REACH YANGTZE RIVER channel adjustment thalweg MIGRATION IDENTIFICATION and classification
宜昌市东风渠简沟渡槽拆除重建工程T梁预应力孔道一次验收合格率QC成果 预览
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作者 覃智清 《水利建设与管理》 2019年第1期74-80,共7页
宜昌市东风渠简沟渡槽拆除重建工程预制预应力T梁作为上部槽身的承重结构,预应力孔道安装质量直接影响T梁结构受力及工程后期运行安全。为此,项目部质量管理QC小组确定了课题,并找出了造成预应力孔道定位筋安装质量问题的要因。通过制... 宜昌市东风渠简沟渡槽拆除重建工程预制预应力T梁作为上部槽身的承重结构,预应力孔道安装质量直接影响T梁结构受力及工程后期运行安全。为此,项目部质量管理QC小组确定了课题,并找出了造成预应力孔道定位筋安装质量问题的要因。通过制定对策并实施,有效地解决了孔道安装施工过程中出现的质量问题。经检查效果良好,可为今后类似工程提供借鉴。 展开更多
关键词 T梁 预应力 孔道 合格率 QC成果
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The total flow control equations and the characteristics of unsteady gradually varied flow in open channels 预览
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作者 Shi-he Liu Qian-yi Zhao Qiu-shi Luo 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期177-185,共9页
Most unsteady channel flows in nature and practical engineering appear as gradually varied ones,and in the free surface,the deformation conforms to the long wave hypothesis.One-dimensional total flow models were usual... Most unsteady channel flows in nature and practical engineering appear as gradually varied ones,and in the free surface,the deformation conforms to the long wave hypothesis.One-dimensional total flow models were usually used to for the numerical simulation of long-term and long-distance reaches to describe the water movements,however,the models lack a clear relationship between the three-dimensional flow field and the total flow field.Moreover,few studies of the variations of the roughness coefficient against the time in unsteady flows were conducted.The following results are obtained through the theoretical analysis and the numerical simulations in this paper.(1) One-dimensional total flow control equations of the unsteady gradually varied flow in open channels are obtained directly from the mathematical model of the viscous fluid motion,and can both reflect the influence of the turbulence and provide an explicit expression of the energy slope term.These equations establish a direct connection between the descriptions of the three-dimensional flow fields and the one-dimensional total flows.(2) Synchronous prototype observation data and planar two-dimensional numerical simulation results are used to extract the one-dimensional total flow information and discuss the total flow characteristics.(3)The orders of magnitude for terms in the total flow motion equation are compared,and the variation of the roughness coefficient against the time is analyzed. 展开更多
关键词 Open CHANNEL UNSTEADY FLOW TOTAL FLOW CHARACTERISTICS control EQUATIONS
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基于国际航运协会(PIANC)规范的港池及航道平面尺度探讨 预览
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作者 汪原也 《水运工程》 北大核心 2019年第8期106-110,116共6页
针对港池和航道平面尺度的分析和计算,PIANC规范提出在概念设计阶段根据自然条件、船舶的基本参数、周边泊位的影响,利用公式对水域尺度进行快速计算,在详细设计阶段应采用仿真试验模拟实际工况,准确地确定航道布置及尺度。以东南亚某LN... 针对港池和航道平面尺度的分析和计算,PIANC规范提出在概念设计阶段根据自然条件、船舶的基本参数、周边泊位的影响,利用公式对水域尺度进行快速计算,在详细设计阶段应采用仿真试验模拟实际工况,准确地确定航道布置及尺度。以东南亚某LNG码头工程为例,将采用PIANC规范公式与仿真试验计算的港口水域尺度进行对比。结果表明,与公式计算相比,仿真试验能更准确、真实地模拟不同工况下的船舶航行轨迹。成果可为类似工程提供借鉴。 展开更多
关键词 港池 航道 平面尺度 仿真 PIANC LNG
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基于时序信息分析的WSN贝叶斯信誉评价模型 预览
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作者 滕志军 郭力文 +1 位作者 吕金玲 侯艳权 《郑州大学学报:工学版》 CAS 北大核心 2019年第1期38-43,共6页
为了有效降低信道占用对节点信誉评价的影响,提高信誉评价模型的准确性,针对数据中断攻击和选择性转发攻击,结合信道状态对网络的影响,引入节点行为时间序列和信道状态时间序列,提出了基于时序信息分析的TS-BRS信誉模型.采用时序分析法... 为了有效降低信道占用对节点信誉评价的影响,提高信誉评价模型的准确性,针对数据中断攻击和选择性转发攻击,结合信道状态对网络的影响,引入节点行为时间序列和信道状态时间序列,提出了基于时序信息分析的TS-BRS信誉模型.采用时序分析法,对两条时间序列匹配分析,降低信道冲突对信誉评价模型的干扰,提高模型识别的准确性;并在信誉值更新中引入适应性维护函数μ,加重现阶段节点行为对信誉值的影响,提高评价模型的适应性.仿真实验表明,新的信誉评价模型能有效提升模型的检测率和检测速度.引入维护函数,网络中被捕获的恶意节点的信誉值可以更快收敛. 展开更多
关键词 无线传感器网络 时间序列 贝叶斯理论 信誉评价 信道
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Assessing the oscillation of channel geometry and meander migration cardinality of Bhagirathi River,West Bengal,India
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作者 Rakhohori Bag Ismail Mondal Jatisankar Bandyopadhyay 《地理学报:英文版》 SCIE CSCD 2019年第4期613-634,共22页
Lateral migration of the Bhagirathi River temporally creates unavoidable geomorphic hazards in West Bengal,India.The Bhagirathi River flows SW for-67.30 km betwee n the confluenee point of Ajay and Jalangi rivers in E... Lateral migration of the Bhagirathi River temporally creates unavoidable geomorphic hazards in West Bengal,India.The Bhagirathi River flows SW for-67.30 km betwee n the confluenee point of Ajay and Jalangi rivers in East Burdwan and Nadia districts of West Bengal.The course of Bhagirathi is notably migration prone and cultivates problematic changes along its course over time.In the study,we have looked into its migration tendency and unpredictability for past 238 years and then predicted the lateral shifting of river centerline using temporal satellite imageries-Landsat-5(TM)of 1987(8,December),1995(28,January),2005(7,January)and LISS-IV satellite imagery(2017,5 January);SOI Toposheet-1968-1969(79A/2,79A/3,79A/6 and 79A/7)and RennelPs map of 1779.Other highlights are the quest of fluvial features,oxbow lakes,mid-channel bars,channel migration rate,meander geometry,channel sinuosity in different parts of river course and the parts that experience intensive bank erosion.The entire river course has been subdivided into three segments;viz.reaches A,B and C.Investigation displays that degree of sinuosity decreases from its anterior course(1968)to the existing course(2017).Reach-specific outputs display that reach B is highly sinuous(SI value 1.94 in 2017)and SI increases temporarily,whereas for reaches A and C it decreases with time.The rate of migration is higher in reach B than that in reaches C and A.The study displays a notably decreasing trend of migration in comparison with its previous lateral migration and shows that the migration nature over time is intensively inconsistent and unpredictable except very few portions of the river course.The nature of deposition within the river channel shows an unstable behavior during the entire period of the study.Meander geometry depicts a rapid change of river course innate to meander bends and shows a higher rate of migration by meander loop cut-off rather than lateral migration that reflects the inconsistency,erosion vulnerability and unpredictable nature of migration.Th 展开更多
关键词 channel GEOMETRY SINUOSITY INDEX BRAIDING INDEX MEANDER GEOMETRY radius of curvature bend tightness INDEX linear regression GIS
Fast-convolution multicarrier based frequency division multiple access
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作者 Yining LI Wenjin WANG +1 位作者 Jiaheng WANG Xiqi GAO 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第8期1-17,共17页
Fast-convolution multicarrier(FCMC), the asynchronous waveform with ultra-low sidelobe, has appeared to be a promising waveform technique for future wireless communications. In this paper, we investigate the filter ba... Fast-convolution multicarrier(FCMC), the asynchronous waveform with ultra-low sidelobe, has appeared to be a promising waveform technique for future wireless communications. In this paper, we investigate the filter bank optimization as well as receiver design including low-complexity channel estimator and equalizer for FCMC based frequency division multiple access(FDMA). Starting from the conventional multi-carrier signals, we first derive a vectorized signal model as a framework to systematically design the FCMC transceiver. For nearly perfect reconstruction(NPR) filter banks design, an optimization criterion which consists of minimizing received signal segments’ mean square error(MSE) is proposed. From the fact that Toeplitz matrices can be asymptotically diagonalized by discrete Fourier transform(DFT) matrix, the channel equalizer can be simplified to one-tap frequency domain equalizer when DFT size is large enough.The minimum mean square error(MMSE) criterion is then applied to calculate the coefficients of onetap frequency domain equalizer. In practice, due to the channel fading, the channel estimation has to be performed to obtain the channel state information(CSI) which is required by the channel equalization. To this end, we propose a combined cyclic prefix(CP) and cyclic suffix(CS) pilot structure which facilitates to estimate the frequency domain CSI directly in the receiver end. The proposed FCMC based FDMA features low-complexity receiver, adjustable users’ bandwidth and low peak-to-average power ratio. Simulation results confirm the performance of the proposed scheme. 展开更多
关键词 MULTIRATE signal processing filter BANKS fast CONVOLUTION channel estimation EQUALIZER
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