期刊文献+
共找到2,866篇文章
< 1 2 144 >
每页显示 20 50 100
Novel quantum secret image-sharing scheme
1
作者 罗高峰 周日贵 胡文文 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第4期61-69,共9页
In this paper, we propose a novel quantum secret image-sharing scheme which constructs m quantum secret images into m+1 quantum share images. A chaotic image generated by the logistic map is utilized to assist in the ... In this paper, we propose a novel quantum secret image-sharing scheme which constructs m quantum secret images into m+1 quantum share images. A chaotic image generated by the logistic map is utilized to assist in the construction of quantum share images first. The chaotic image and secret images are expressed as quantum image representation by using the novel enhanced quantum representation. To enhance the confidentiality, quantum secret images are scrambled into disordered images through the Arnold transform. Then the quantum share images are constructed by performing a series of quantum swap operations and quantum controlled-NOT operations. Because all quantum operations are invertible, the original quantum secret images can be reconstructed by performing a series of inverse operations. Theoretical analysis and numerical simulation proved both the security and low computational complexity of the scheme, which has outperformed its classical counterparts. It also provides quantum circuits for sharing and recovery processes. 展开更多
关键词 QUANTUM IMAGE processing SECRET IMAGE SHARING QUANTUM COMPUTATION QUANTUM CIRCUIT
Prognostic Values of Serum Chloride and Sodium Levels in Patients with Three-vessel Disease 预览
2
作者 ZHANG Ce WANG Dong +15 位作者 HOU Bing Jie JIANG Lin XU Lian Jun TIAN Jian ZHAO Yan Yan ZHAO Xue Yan FENG Xin Xing ZHANG Yin SUN Kai XU Bo ZHAO Wei HUI Ru Tai GAO Run Lin LOU Hui Ling YUAN Jin Qing SONG Lei 《生物医学与环境科学:英文版》 SCIE CAS CSCD 2019年第4期250-259,共10页
Objective Identification of new risk factors is needed to improve prediction of adverse outcomes in patients with three-vessel disease(TVD). The present study aimed to evaluate the prognostic values of serum chloride ... Objective Identification of new risk factors is needed to improve prediction of adverse outcomes in patients with three-vessel disease(TVD). The present study aimed to evaluate the prognostic values of serum chloride and sodium levels in patients with TVD. Methods We used data from a prospective cohort of consecutive patients with angiographically confirmed TVD. The primary endpoint was all-cause death. Cox proportional hazard regression was used to analyze the relationship of serum chloride and sodium levels with long-term outcomes of TVD patients. Results A total of 8,318 participants with available serum chloride and sodium data were included in this analysis. At baseline, patients in the low tertiles group of serum chloride level(≤ 102.0 mmol/L) or serum sodium level(≤ 139.0 mmol/L) had more severe disease conditions. During a median follow-up of 7.5-year, both low serum chloride level and low serum sodium level were found to be associated with an increased risk for mortality in univariate analysis. However, when both parameters were incorporated into a multivariate model, only low serum sodium level remained to be an independent predictor of all-cause death(hazard ratio: 1.16, 95% confidence interval: 1.01-1.34, P = 0.041). Modest but significant improvement of discrimination was observed after incorporating serum sodium level into the Synergy between percutaneous coronary intervention(PCI) with Taxus and Cardiac Surgery score. Conclusion Serum sodium level is more strongly associated with long-term outcomes of TVD patients compared with serum chloride level. Low serum sodium level is an independent risk factor for mortality, but only provides modest prognostic information beyond an established risk model. 展开更多
关键词 CORONARY disease PROGNOSIS Biomarkers
在线阅读 下载PDF
A PSO Based Multi-Domain Virtual Network Embedding Approach 预览
3
作者 Yongjing Ni Guoyan Huang +3 位作者 Sheng Wu Chenxi Li Peiying Zhang Haipeng Yao 《中国通信:英文版》 SCIE CSCD 2019年第4期105-119,共15页
This paper proposed a multi-domain virtual network embedding algorithm based on multi-controller SDN architecture.The local controller first selects candidate substrate nodes for each virtual node in the domain.Then t... This paper proposed a multi-domain virtual network embedding algorithm based on multi-controller SDN architecture.The local controller first selects candidate substrate nodes for each virtual node in the domain.Then the global controller abstracts substrate network topology based on the candidate nodes and boundary nodes of each domain,and applies Particle Swarm Optimization Algorithm on it to divide virtual network requests.Each local controller then embeds the virtual nodes of the divided single-domain virtual network requests in the domain,and cooperates with other local controllers to embed the inter-domain virtual links.Simulation experimental results show that the proposed algorithm has good performance in reducing embedding cost with good stability and scalability. 展开更多
关键词 MULTI-DOMAIN VIRTUAL NETWORK EMBEDDING CANDIDATE node particle swarm optimization algorithm VIRTUAL NETWORK REQUEST division
在线阅读 下载PDF
Predictability of Ensemble Forecasting Estimated Using the Kullback–Leibler Divergence in the Lorenz Model 预览
4
作者 Ruiqiang DING Baojia LIU +2 位作者 Bin GU Jianping LI Xuan LI 《大气科学进展:英文版》 SCIE CAS CSCD 2019年第8期837-846,共10页
A new method to quantify the predictability limit of ensemble forecasting is presented using the Kullback–Leibler(KL)divergence(also called the relative entropy), which provides a measure of the difference between th... A new method to quantify the predictability limit of ensemble forecasting is presented using the Kullback–Leibler(KL)divergence(also called the relative entropy), which provides a measure of the difference between the probability distributions of ensemble forecasts and local reference(true) states. The KL divergence is applicable to a non-normal distribution of ensemble forecasts, which is a substantial improvement over the previous method using the ensemble spread. An example from the three-variable Lorenz model illustrates the effectiveness of the KL divergence, which can effectively quantify the predictability limit of ensemble forecasting. On this basis, the KL divergence is used to investigate the dependence of the predictability limit of ensemble forecasting on the initial states and the magnitude of initial errors. The local predictability limit of ensemble forecasting varies considerably with the initial states, as well as with the magnitude of initial errors. Further research is needed to examine the real-world applications of the KL divergence in measuring the predictability of ensemble weather forecasts. 展开更多
关键词 PREDICTABILITY ENSEMBLE forecasting Kullback–Leibler DIVERGENCE
在线阅读 下载PDF
Triple α-particle resonances in the decay of hot nuclear systems
5
作者 张苏雅拉吐 王金成 +6 位作者 A.Bonasera 黄美容 郑华 张国强 Z.Kohley 马余刚 S.J.Yennello 《中国物理C:英文版》 SCIE CAS CSCD 2019年第6期32-37,共6页
The Efimov(Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64)Zn(64 Ni)+ 70(64)Zn(64 Ni) reactions at the beam energy of E/A... The Efimov(Thomas) trimers in excited 12 C nuclei, for which no observation exists yet, are discussed by means of analyzing the experimental data of 70(64)Zn(64 Ni)+ 70(64)Zn(64 Ni) reactions at the beam energy of E/A = 35 MeV/nucleon. In heavy ion collisions, a-particles interact with each other and can form complex systems such as 8 Be and 12 C. For the 3 a-particle systems,multi-resonance processes give rise to excited levels of 12 C. The interaction between any two of the 3 a-particles provides events with one, two or three 8 Be. Their interfering levels are clearly seen in the minimum relative energy distributions. Events with the three a-particle relative energies consistent with the ground state of 8 Be are observed with the decrease of the instrumental error for the reconstructed 7.458 MeV excitation level in 12 C, which was suggested as the Efimov(Thomas) state. 展开更多
关键词 heavy ion REACTIONS Efimov state α-particle RESONANCES relative KINETIC energy
Structural,mechanical,and electronic properties of 25 kinds ofⅢ–Ⅴbinary monolayers:A computational study with first-principles calculation
6
作者 刘雪飞 罗子江 +5 位作者 周勋 魏节敏 王一 郭祥 吕兵 丁召 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第8期258-269,共12页
Using first-principle calculations,we investigate the mechanical,structural,and electronic properties and formation energy of 25 kinds ofⅢ-Ⅴ binary monolayers in detail.A relative radius of the binary compound accor... Using first-principle calculations,we investigate the mechanical,structural,and electronic properties and formation energy of 25 kinds ofⅢ-Ⅴ binary monolayers in detail.A relative radius of the binary compound according to the atomic number in the periodic table is defined,and based on the definition,the 25 kinds ofⅢ-Ⅴ binary compounds are exactly located at a symmetric position in a symmetric matrix.The mechanical properties and band gaps are found to be very dependent on relative radius,while the effective mass of holes and electrons are found to be less dependent.A linear function between Young’s modulus and formation energy is fitted with a linear relation in this paper.The change regularity of physical properties of B-Ⅴ(Ⅴ=P,As,Sb,Bi)andⅢ-N(Ⅲ=Al,Ga,In,Tl)are found to be very different from those of otherⅢ-Ⅴ binary compounds. 展开更多
关键词 DENSITY FUNCTIONAL theory Ⅲ-Ⅴbinary monolayers BAND structure MECHANICAL properties
Observatory science with eXTP
7
作者 Jean J. M. in 't Zand Enrico Bozzo +103 位作者 JinLu Qu Xiang-Dong Li Lorenzo Amati Yang Chen Immacolata Donnarumma Victor Doroshenko Stephen A. Drake Margarita Hernanz Peter A. Jenke Thomas J. Maccarone Simin Mahmoodifar Domitilla de Martino Alessandra De Rosa Elena M. Rossi Antonia Rowlinson Gloria Sala Giulia Stratta Thomas M. Tauris Joern Wilms XueFeng Wu Ping Zhou Iván Agudo Diego Altamirano Jean-Luc Atteia Nils A. Andersson M. Cristina Baglio David R. Ballantyne Altan Baykal Ehud Behar Tomaso Belloni Sudip Bhattacharyya Stefano Bianchi Anna Bilous Pere Blay Jo ao Braga S?ren Brandt Edward F. Brown Niccolò Bucciantini Luciano Burderi Edward M. Cackett Riccardo Campana Sergio Campana Piergiorgio Casella Yuri Cavecchi Frank Chambers Liang Chen Yu-Peng Chen Jérome Chenevez Maria Chernyakova ChiChuan Jin Riccardo Ciolfi Elisa Costantini Andrew Cumming Antonino D'Aì Zi-Gao Dai Filippo D'Ammando Massimiliano De Pasquale Nathalie Degenaar Melania Del Santo Valerio D'Elia Tiziana Di Salvo Gerry Doyle Maurizio Falanga XiLong Fan Robert D. Ferdman Marco Feroci Federico Fraschetti Duncan K. Galloway Angelo F. Gambino Poshak Gandhi MingYu Ge Bruce Gendre Ramandeep Gill Diego Gotz Christian Gouiffès Paola Grandi Jonathan Granot Manuel Güdel Alexander Heger Craig O. Heinke Jeroen Homan Rosario Iaria Kazushi Iwasawa Luca Izzo Long Ji Peter G. Jonker Jordi José Jelle S. Kaastra Emrah Kalemci Oleg Kargaltsev Nobuyuki Kawai Laurens Keek Stefanie Komossa Ingo Kreykenbohm Lucien Kuiper Devaky Kunneriath Gang Li En-Wei Liang Manuel Linares Francesco Longo FangJun Lu Alexander A. Lutovinov Denys Malyshev Julien Malza 《中国科学:物理学、力学、天文学英文版》 SCIE EI CAS CSCD 2019年第2期97-138,共42页
In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related toObservatory Science targets. These include flaring stars, supernova remnants, accreting wh... In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry (eXTP) mission for studies related toObservatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-raybinaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellentlysuited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium ledby the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in themid 2020s. 展开更多
关键词 space research instruments nuclear ASTROPHYSICS flare stars ACCRETION and ACCRETION disks mass loss and stellar winds cataclysmic BINARIES X-RAY BINARIES supernova REMNANTS active galactic nuclei X-RAY BURSTS gamma-ray BURSTS gravitational waves
基于小波变换和改进中值滤波的医学图像耦合去噪算法 预览
8
作者 陈炳权 崔金鸽 +2 位作者 徐庆 舒婷 刘宏立 《中南大学学报:英文版》 SCIE EI CAS CSCD 2019年第1期120-131,共12页
为了克服医学图像采集和传输过程中的图像模糊和边缘丢失现象,提出了一种基于小波变换和改进中值滤波的医学图像耦合去噪方法。该方法由四个模块组成:图像采集,图像存储,图像处理和图像重建。图像采集,获取包含高斯噪声和脉冲噪声的医... 为了克服医学图像采集和传输过程中的图像模糊和边缘丢失现象,提出了一种基于小波变换和改进中值滤波的医学图像耦合去噪方法。该方法由四个模块组成:图像采集,图像存储,图像处理和图像重建。图像采集,获取包含高斯噪声和脉冲噪声的医学图像。图像存储,包括原始图像和处理后图像的数据、参数等信息的保存。在第三模块中,通过小波分解将医学图像分解为四个子带(LL,HL,LH,HH),其中LL为低频部分,LH,HL,HH分别为水平,垂直和对角线高频部分。利用改进的小波阈值处理高频系数,保留低频系数,并在小波阈值处理后对三个高频子带进行改进中值滤波处理。最后一个模块是图像重建,即通过小波重构去噪后的图像。这种方法的优点是结合中值滤波和小波的优点,去噪效果更好,而不是前两种方法的简单组合。通过DWT和改进的中值滤波器系数耦合去噪,对于包含复杂噪声的高精度医学图像处理非常实用。将所提算法的实验结果与中值滤波,小波变换,Contourlet和DT-CWT等方法的结果进行了比较。根据视觉评价指标PSNR和SNR以及Canny边缘检测得出:在低噪声图像中,PSNR和SNR分别提高10%~15%;在高噪声图像中,PSNR和SNR增加2%~6%。与其他方法相比,该算法取得了较好的结果,为医学诊断提供了重要方法。 展开更多
关键词 医学图像 图像去噪 小波变换 改进中值滤波 耦合去噪
在线阅读 免费下载
Plasma electrolytic liquefaction of sawdust
9
作者 蒋匆聪 刘诗筠 +7 位作者 冯哲 方志 张先徽 梅丹华 席登科 栾秉钰 王兴权 杨思泽 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第4期425-432,共8页
As a renewable carbon resource, biomass can be converted into polyols, aromatic hydrocarbons, alkanes, and other products by traditional catalytic liquefaction method, which has been widely used in production and life... As a renewable carbon resource, biomass can be converted into polyols, aromatic hydrocarbons, alkanes, and other products by traditional catalytic liquefaction method, which has been widely used in production and life. The efficient development and utilization of biomass energy will play a very positive role in solving the problems of energy and ecological environment. A way of combining the plasma electrolysis with traditional catalytic liquefaction realizes the efficient liquefaction of sawdust, which provides a new liquefaction way for traditional biomass conversion. In this experiment, the effects of solution composition, catalyst content and power supply on solution resistance and liquefaction rate are analyzed.It is found that solution composition and catalyst content have a great influence on solution resistance. The results show that the liquefaction rate is highest and the resistance is smallest when the solution resistance is 500Ω. The liquefaction rate is greatly affected by the solution temperature, and the solution temperature is determined by the output power between the two electrodes. The output power includes the heating power of the electric field and the discharge power of the plasma.We measure the electric potential field distribution in the solution and the plasma power. It is found that the output power between the two poles increases nonlinearly(from 0 to 270 W) with time. In two minutes, the electric field heating power increases from 0 to 105 W and then decreases to 70 W, while the plasma power increases from 0 to 200 W. It is well known that in the first 70 seconds of the experiment the electric field heating is dominant, and then the plasma heating turns into a main thermal source. In this paper, plasma electrolysis and traditional catalytic liquefaction are combined to achieve the efficient liquefaction of sawdust, which provides a new way for biomass liquefaction. 展开更多
关键词 BIOMASS LIQUEFACTION PLASMA electrolytic
Broadband absorption of graphene from magnetic dipole resonances in hybrid nanostructure 预览
10
作者 Xiaowei Jiang 《半导体学报:英文版》 EI CAS CSCD 2019年第6期69-72,共4页
As emerging new material, graphene has inspired great research interest. However, most of the studies focused on how to improve the absorption efficiency of graphene, but payed little attention on broadening absorptio... As emerging new material, graphene has inspired great research interest. However, most of the studies focused on how to improve the absorption efficiency of graphene, but payed little attention on broadening absorption bandwidth while ensuring high absorption efficiency. In this work, we proposed a hybrid nanostructure, which not only can improve absorption efficiency but also can increase absorption bandwidth. The proposed hybrid nanostructure consists of a monolayer graphene sandwiched between three Ag gratings with different widths and a SiO2 spacer on a Ag substrate, these three gratings and substrate can excite three independent magnetic dipole resonances. In our calculations, we numerically demonstrate the proposed hybrid structure can achieve graphene absorption bandwidth of 0.311 μm in near-infrared region with absorption exceeding 30%. We also studied absorption peaks dependence on gratings widths and SiO2 spacer thickness, and explained the results using physical mechanism. Our research can provide a theoretical guidance for future device preparation. 展开更多
关键词 GRAPHENE ABSORPTION BANDWIDTH magnetic DIPOLE GRATING
在线阅读 下载PDF
Solvability and thermal response of cellulose with different crystal configurations
11
作者 Qian CHEN Kai ZHENG +4 位作者 Qingtao FAN Kun WANG Haiyan YANG Jianxin JIANG Shijie LIU 《工程管理前沿:英文版》 2019年第1期62-69,共8页
Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial ut... Cellulose is a biodegradable and renewable natural material that it is naturally resistant to breaking and modification. Moreover, the crystalline structure of cellulose is a major factor restricting its industrial utilization. In this study, cellulose polymorphs were prepared from natural cellulose, and their solvability and thermal response were investigated. Using liquid- and solid-state NMR signals, the distinct types and dissolving states of cellulose polymorphs were identified. The thermal behavior of the polymorphic forms of cellulose-d was also evaluated, and cellulose Ⅱ exhibited the poorest thermal stability and a unique exothermic reaction. 展开更多
关键词 CELLULOSE CRYSTAL structure thermal response XRD CP/MAS^13C NMR
A new co-culture method for identifying synaptic adhesion molecules involved in synapse formation
12
作者 Wei Jiang Jihong Gong +1 位作者 Yi Rong Xiaofei Yang 《生物物理学报:英文版》 CSCD 2019年第2期91-97,共7页
The proper formation of synapses is essential for brain function. Synaptic cell adhesion molecules (CAMs) are thought to play essential roles in the initiation of the synapse formation process. The artificial synapse ... The proper formation of synapses is essential for brain function. Synaptic cell adhesion molecules (CAMs) are thought to play essential roles in the initiation of the synapse formation process. The artificial synapse formation assay, in which non-neuronal cells and neurons are co-cultured, has been shown to be a powerful system for screening CAMs. However;controlling a large number of cell pools in co-culture is complicated, creating a potential barrier for high-throughput screening. This protocol describes a new co-culture method in which cDNA plasmid is transfected into human embryonic kidney 293T cells using polyetherimide 24 h after cells were mixed with neurons, and immunostaining and confocal imaging are employed for analyzing synaptogenesis. This optimized method is simpler and easier to perform than the traditional method for the examination of the synaptogenic activities of individual cell-surface proteins in isolation, and provides an unbiased screening platform for synaptogenic proteins. 展开更多
关键词 CO-CULTURE ASSAY SYNAPSE formation SYNAPTIC cell adhesion MOLECULES POLYETHERIMIDE
First-Stokes Wavelengths at 1175.8 and 1177.1nm Generated in a Diode End-Pumped Nd:YVO4/LuVO4 Raman Laser
13
作者 周青青 施沈城 +5 位作者 陈思梦 段延敏 张喜梅 郭锦 赵斌 朱海永 《中国物理快报:英文版》 SCIE CAS CSCD 2019年第1期32-35,共4页
A diode end-pumped acousto-optic Q-switched Nd:YVO4/LuVO4 Raman laser is demonstrated.Both YV04 and LuVO4 can work as Raman gain,and slightly different active vibration modes of both crystals can result in different f... A diode end-pumped acousto-optic Q-switched Nd:YVO4/LuVO4 Raman laser is demonstrated.Both YV04 and LuVO4 can work as Raman gain,and slightly different active vibration modes of both crystals can result in different flrst-Stokes wavelengths.The output characteristic as the Raman competition between YVO4 and LuVO4 crystals dor the laser systems with both shared cavity and coupled cavity is experimentally investigated. For the shared cavity,simultaneous Raman conversion in both YVO4 and LuVO4 crystals is achieved with dualwavelength emission at 1175.8 and 1177.1 nm.The maximum output power of 1.03 Wand the conversion efficiency of 10.3% are obtained.The 0.84 W single first Stokes wavelength at 1177.1 nm with LuV04 Raman conversion is achieved with the coupled cavity.The results show that the coupled cavity with short Raman cavity can obtain a narrow pulse width.The separated laser crystal and Raman gain media with different vanadates in shared cavity have advantages in achieving dual-wavelength lasers with small frequency intervals. 展开更多
关键词 Tox WAVELENGTH DIODE side PUMP Raman laser
Formation control with obstacle avoidance of second-order multi-agent systems under directed communication topology
14
作者 Guoxing WEN CLPhilip CHEN +2 位作者 Hui DOU Hongli YANG Chunfang LIU 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第9期144-157,共14页
This paper addresses the obstacle avoidance problem of formation control for the multi-agent systems modeled by double integrator dynamics under a directed interconnection topology. The control task is finished by a l... This paper addresses the obstacle avoidance problem of formation control for the multi-agent systems modeled by double integrator dynamics under a directed interconnection topology. The control task is finished by a leader-follower formation scheme combined with an artificial potential field(APF) method.The leader-follower scheme is carried out by taking the desired trajectory with the desired velocity as virtual leader, while the APF method is carried out by dealing with the obstacles as the high potential points. When the obstacle avoidance tasks are finished, the artificial potential forces degrade the formation performance, so their undesired effects are treated as disturbances, which is analyzed by the robust H∞performance. Based on Lyapunov stability theory, it is proved that the proposed formation approach can realize the control objective. The result is also extended to the switching multi-agent formation. The effectiveness of the proposed formation scheme is further confirmed by simulation studies. 展开更多
关键词 formation control OBSTACLE AVOIDANCE artificial potential field method H_∞ performance SECOND-ORDER multi-agent system directed TOPOLOGY
Regional and Global Land Data Assimilation Systems: Innovations,Challenges, and Prospects
15
作者 Youlong XIA Zengchao HAO +5 位作者 Chunxiang SHI Yaohui LI Jesse MENG Tongren XU Xinying WU Baoqing ZHANG 《气象学报:英文版》 SCIE CSCD 2019年第2期159-189,共31页
Since the North American and Global Land Data Assimilation Systems(NLDAS and GLDAS) were established in2004, significant progress has been made in development of regional and global LDASs. National, regional, projectb... Since the North American and Global Land Data Assimilation Systems(NLDAS and GLDAS) were established in2004, significant progress has been made in development of regional and global LDASs. National, regional, projectbased, and global LDASs are widely developed across the world. This paper summarizes and overviews the development, current status, applications, challenges, and future prospects of these LDASs. We first introduce various regional and global LDASs including their development history and innovations, and then discuss the evaluation, validation, and applications(from numerical model prediction to water resources management) of these LDASs. More importantly, we document in detail some specific challenges that the LDASs are facing: quality of the in-situ observations, satellite retrievals, reanalysis data, surface meteorological forcing data, and soil and vegetation databases;land surface model physical process treatment and parameter calibration;land data assimilation difficulties;and spatial scale incompatibility problems. Finally, some prospects such as the use of land information system software, the unified global LDAS system with nesting concept and hyper-resolution, and uncertainty estimates for model structure,parameters, and forcing are discussed. 展开更多
关键词 LAND data ASSIMILATION system (LDAS) REGIONAL and GLOBAL LDASs in-situ observation satellite RETRIEVAL LAND surface model (LSM)
Design of Irregular QC-LDPC Code Based Multi-Level Coded Modulation Scheme for High Speed Optical Communication Systems 预览
16
作者 Liqian Wang Dongdong Wang +3 位作者 Yongjing Ni Xue Chen Midou Cui Fu Yang 《中国通信:英文版》 SCIE CSCD 2019年第5期106-120,共15页
In this paper, we focus on the design of irregular QC-LDPC code based multi-level coded modulation(MLCM) scheme by jointly optimizing the component code rate and the degree distribution of the irregular QC-LDPC compon... In this paper, we focus on the design of irregular QC-LDPC code based multi-level coded modulation(MLCM) scheme by jointly optimizing the component code rate and the degree distribution of the irregular QC-LDPC component code. Firstly, the sub-channel capacities of MLCM systems is analyzed and discussed, based on which the optimal component code rate can be obtained. Secondly, an extrinsic information transfer chart based two-stage searching algorithm is proposed to find the good irregular QC-LDPC code ensembles with optimal component code rates for their corresponding sub-channels. Finally, by constructing the irregular QC-LDPC component codes from the designed ensembles with the aim of possibly enlarging the girth and reducing the number of the shortest cycles, the designed irregular QC-LDPC code based 16QAM and 64QAM MLCM systems can achieve 0.4 dB and 1.2 dB net coding gain, respectively, compared with the recently proposed regular QC-LDPC code based 16QAM and 64QAM MLCM systems. 展开更多
关键词 quasi-cyclic LOW-DENSITY parity check (QC-LDPC) code irregular EXTRINSIC INFORMATION transfer(EXIT) chart generalized mutual information(GMI) MULTI-LEVEL coded modulation(MLCM)
在线阅读 下载PDF
A Prediction Mode of Crop Canopy Nitrogen Hyperspectral Under Mode of"Cornfield Goose Breeding" 预览
17
作者 Wang Shu-wen Ma Xin-yu +11 位作者 Guo Chun-fei Guo Yong-gang Zhang Yan Zhao Zhong-yuan Wang Chaofan Chen Xiao-liang Liu Jun Li Rui-xuan Li Si-jia Xu kun Gao Jia-ying Wang Run-tao 《东北农业大学学报:英文版》 CAS 2019年第2期75-86,共12页
The corn canopy taking in before and after grazing term in the production mode of"cornfield goose"was used as the research object.Hyperspectral techniques were used to analyze the spectral characteristics of... The corn canopy taking in before and after grazing term in the production mode of"cornfield goose"was used as the research object.Hyperspectral techniques were used to analyze the spectral characteristics of corn canopy leaves in different periods,and a full-band based Principal Component Regression model,Partial Least Squares Regression model and Support Vector Machine regression model were established to propose a fast,convenient and efficient hyperspectral imaging detection technique.The results showed that the nitrogen value of the grazing area was always lower than that of the control area,during the grazing period,the reflectance of the near-infrared spectrum increased,and the red edge position moved to the left.In terms of model establishment,the optimal model was obtained for different grazing periods.The positive set determining coefficient(Rc 2),the root-mean-square error correction(RMSEC),the prediction set decision coefficient(Rp 2)and the root-mean-square error prediction(RMSEP)were obtained by using SNV-BICA-PCA-PLS in the pre-grazing period.Their values were 0.9136,0.1750,0.8910 and 0.1052,respectively.The values of Rc 2,RMSEC,Rp 2 and RMSEP were 0.9006,0.0418,0.8508 and 0.1233,respectively,when they were obtained by using MSC-BICA-PCA-MSC in the post-grazing period.The research results provided support and help for the future"agriculture and animal husbandry integration"to optimize production management and establish a nitrogen nutrient balance model. 展开更多
关键词 HYPERSPECTRAL agriculture and animal HUSBANDRY integration NITROGEN CORN CANOPY
在线阅读 下载PDF
Optimal Energy-Efficient Transmission for Hybrid Spectrum Sharing in Cooperative Cognitive Radio Networks 预览
18
作者 Linna Hu Rui Shi +3 位作者 Minghe Mao Zhiyu Chen Hongxi Zhou Weiliang Li 《中国通信:英文版》 SCIE CSCD 2019年第6期150-161,共12页
In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user syste... In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user systems to achieve the maximum energy efficiency in a cognitive network based on hybrid spectrum sharing,meanwhile considering the maximum transmit power,user quality of service(QoS)requirements,interference limitations,and primary user protection.The optimization of energy efficient sensing time and power allocation is formulated as a non-convex optimization problem.The Dinkelbach’s method is adopted to solve this problem and to transform the non-convex optimization problem in fractional form into an equivalent optimization problem in the form of subtraction.Then,an iterative power allocation algorithm is proposed to solve the optimization problem.The simulation results show the effectiveness of the proposed algorithms for energy-efficient resource allocation in the cognitive network. 展开更多
关键词 cognitive radio networks COOPERATIVE SPECTRUM SENSING ENERGY-EFFICIENCY HYBRID SPECTRUM sharing power control SENSING time optimization
在线阅读 下载PDF
Structure Optimization for Echo State Network Based on Contribution
19
作者 Dingyuan Li Fu Liu +1 位作者 Junfei Qiao Rong Li 《清华大学学报自然科学版(英文版)》 EI CAS CSCD 2019年第1期97-105,共9页
Echo State Network (ESN)is a recurrent neural network with a large,randomly generated recurrent part called the dynamic reservoir.Only the output weights are modified during training.However,proper balancing of the tr... Echo State Network (ESN)is a recurrent neural network with a large,randomly generated recurrent part called the dynamic reservoir.Only the output weights are modified during training.However,proper balancing of the trade-off between the structure and performance for ESN remains a difficult task.In this paper,a structure optimized method for ESN based on contribution is proposed to simplify its network structure and improve its performance. First,we evaluate the contribution of reservoir neurons.Second,we present a pruning mechanism to remove the unimportant connection weights of reservoir neurons with low contribution.Finally,the new output weights are learned with the pseudo inverse method.The novel optimized ESN,named C-ESN,is tested on a Lorenz chaotic time-series prediction and an actual municipal sewage treatment system.The simulation results show that the C-ESN can have better prediction and generalization performance than ESN. 展开更多
关键词 NEURAL NETWORK STRUCTURAL DESIGN time-series PREDICTION
Cis-2-dodecenoic Acid Mediates Its Synergistic Effect with Triazoles by Interfering with Efflux Pumps in Fluconazole-resistant Candida albicans 预览
20
作者 YANG Dong Liang HU Yan Ling +7 位作者 YIN Zi Xin ZENG Gui Sheng LI Dan ZHANG Yu Qian XU Zhen Hua GUAN Xiao Ming WENG Li Xing WANG Lian Hui 《生物医学与环境科学:英文版》 SCIE CAS CSCD 2019年第3期199-209,共11页
Objective To evaluate the synergy of the Burkholderia signaling molecule cis-2-dodecenoic acid (BDSF) and fluconazole (FLU) or itraconazole (ITRA) against two azole-resistant C. albicans clinical isolates in vitro and... Objective To evaluate the synergy of the Burkholderia signaling molecule cis-2-dodecenoic acid (BDSF) and fluconazole (FLU) or itraconazole (ITRA) against two azole-resistant C. albicans clinical isolates in vitro and in vivo. Methods Minimum inhibitory concentrations (MICs) of antibiotics against two azole-resistant C. albicans were measured by the checkerboard technique, E-test, and time-kill assay. In vivo antifungal synergy testing was performed on mice. Analysis of the relative gene expression levels of the strains was conducted by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Results BDSF showed highly synergistic effects in combination with FLU or ITRA with a fractional inhibitory concentration index of ≤ 0.08. BDSF was not cytotoxic to normal human foreskin fibroblast cells at concentrations of up to 300 μg/mL. The qRT-PCR results showed that the combination of BDSF and FLU/ITRA significantly inhibits the expression of the efflux pump genes CDR1 and MDR1 via suppression of the transcription factors TAC1 and MRR1, respectively, when compared with FLU or ITRA alone. No dramatic difference in the mRNA expression levels of ERG1, ERG11, and UPC2 was found, which indicates that the drug combinations do not significantly interfere with UPC2-mediated ergosterol levels. In vivo experiments revealed that combination therapy can be an effective therapeutic approach to treat candidiasis. Conclusion The synergistic effects of BDSF and azoles may be useful as an alternative approach to control azole-resistant Candida infections. 展开更多
关键词 C. ALBICANS Cis-2-dodecenoic acid azole-resistant Combination MDR1 CDR1
在线阅读 下载PDF
上一页 1 2 144 下一页 到第
使用帮助 返回顶部 意见反馈