检索结果-南通市图书馆

Model Calculation of n + 6Li Reactions Below 20 MeV

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2001年第10期36卷 437-442页

作者： ZHANG Jing-Shang HAN yin-lu China Nuclear Data Center China Institute of Atomic Energy Beijing 102413 China China Nuclear Data Center China Institute of Atomic Energy Beijing 102413 China

Based on the unified Hauser-Feshbach and exciton model for light nuclei, the calculations of reaction cross sections and the double-differential cross sections for n + 6Li are performed. Since all of the first-particle emissions are from the compound nucleus to the discrete levels, the angular momentum coupling effect in pre-equilibrium mechanism must be taken into account. The fitting of the measured data indicates that the three-body break-up process needs to be involved, and the pre-equilibrium reaction mechanism dominates the reaction processes. In light nucleus reactions the recoil effect must be taken into account.

关键词： pre-equilibrium emission, discrete levels, three-body break-up process

Efficient closed-form solution for target localization using TDOA measurements in the presence of sensor position errors

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Journal of China Universities of Posts and Telecommunications 2017年第4期24卷 1-9,15页

作者： Yan Leibing Zhang Yerong lu yin School of Electronic Science and Engineering Nanjing University of Posts and Telecommunications Department of Electronics and Communication Engineering Henan Institute of Technology

An efficient solution for locating a target was proposed, which by using time difference of arrival （TDOA） measurements in the presence of random sensor position errors to increase the accuracy of estimation. The cause of position estimation errors in two-stage weighted least squares （TSWLS） method is analyzed to develop a simple and effective method for improving the localization performance. Specifically, the reference sensor is selected again and the coordinate system is rotated according to preliminary estimated target position by using TSWLS method, and the final position estimation of the target is obtained by using weighted least squares （WLS）. The proposed approach exhibits a closed-form and is as efficient as TSWLS method. Simulation results show that the proposed approach yields low estimation bias and improved robustness with increasing sensor position errors and thus can easily achieve the Cramer-Rao lower bound （CRLB） easily and effectively improve the localization accuracy.

关键词： target localization TDOA sensor position errors CRLB

Numerical stabilities of loosely coupled methods for robust modeling of lightweight and flexible structures in incompressible and viscous flows

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2017年第4期33卷 709-724页

作者： Deniz Tolga Akcabay Jian Xiao yin lu Young Department of Naval Architecture and Marine Engineering University of Michigan 2600 Draper Dr. Ann ArborMI 48109-2145 USA

The growing interest to examine the hydroelastic dynamics and stabilities of lightweight and flexible materials requires robust and accurate fluid–structure interaction（FSI）models. Classically, partitioned fluid and structure solvers are easier to implement compared to monolithic methods;however, partitioned FSI models are vulnerable to numerical（“virtual added mass”） instabilities for cases when the solid to fluid density ratio is low and if the flow is *** a partitioned method, the loosely hybrid coupled（LHC）method, which was introduced and validated in Young et al.（Acta Mech. Sin. 28：1030–1041, 2012）, has been successfully used to efficiently and stably model lightweight and flexible structures. The LHC method achieves its numerical stability by, in addition to the viscous fluid forces, embedding potential flow approximations of the fluid induced forces to transform the partitioned FSI model into a semi-implicit scheme. The objective of this work is to derive and validate the numerical stability boundary of the LHC. The results show that the stability boundary of the LHC is much wider than traditional loosely coupled methods for a variety of numerical integration schemes. The results also show that inclusion of an estimate of the fluid inertial forces is the most critical to ensure the numerical stability when solving for fluid–structure interaction problems involving cases with a solid to fluid-added mass ratio less than one.

关键词： incompressible viscous lightweight partitioned validated discretization solver embedding stably Reynolds

Novel infrared and visible image fusion method based on independent component analysis

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2014年第2期8卷 243-254页

作者： yin lu Fuxiang WANG Xiaoyan luO Feng LIU National Key Laboratory of CNS/ATM School of Electronics and Information Engineering Beihang University Beijing 100191 China

The goal of infrared （IR） and visible image fu- sion is for the fused image to contain IR object features from the IR image and retain the visual details provided by the visible image. The disadvantage of traditional fusion method based on independent component analysis （ICA） is that the primary feature information that describes the IR objects and the secondary feature information in the IR image are fused into the fused image. Secondary feature information can de- press the visual effect of the fused image. A novel ICA-based IR and visible image fusion scheme is proposed in this paper. ICA is employed to extract features from the infrared image, and then the primary and secondary features are distinguished by the kurtosis information of the ICA base coefficients. The secondary features of the IR image are discarded during fu- sion. The fused image is obtained by fusing primary features into the visible image. Experimental results show that the pro- posed method can provide better perception effect.

关键词： image fusion independent component analysis(ICA) feature extraction kurtosis

Joint Optimization of Resource Allocation and Trajectory Based on User Trajectory for UAV-Assisted Backscatter Communication System

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

China Communications 2024年第2期21卷 197-209页

作者： Peizhong Xie Junjie Jiang Ting Li yin lu School of Communication and Information Engineering Nanjing University of Posts and TelecommunicationsNanjing 210003China Key Lab of Broadband Wireless Communication and Sensor Network Technology(Nanjing University of Posts and Telecommunications) Ministry of EducationNanjing 210003China

The Backscatter communication has gained widespread attention from academia and industry in recent years. In this paper, A method of resource allocation and trajectory optimization is proposed for UAV-assisted backscatter communication based on user trajectory. This paper will establish an optimization problem of jointly optimizing the UAV trajectories, UAV transmission power and BD scheduling based on the large-scale channel state signals estimated in advance of the known user trajectories, taking into account the constraints of BD data and working energy consumption, to maximize the energy efficiency of the system. The problem is a non-convex optimization problem in fractional form, and there is nonlinear coupling between optimization *** iterative algorithm is proposed based on Dinkelbach algorithm, block coordinate descent method and continuous convex optimization technology. First, the objective function is converted into a non-fractional programming problem based on Dinkelbach method,and then the block coordinate descent method is used to decompose the original complex problem into three independent sub-problems. Finally, the successive convex approximation method is used to solve the trajectory optimization sub-problem. The simulation results show that the proposed scheme and algorithm have obvious energy efficiency gains compared with the comparison scheme.

关键词： energy efficiency joint optimization UAV-assisted backscatter communication user trajectory

Microstructure and microwave dielectric properties of ZnO-B_2O_3 added (Ca_(0.254)Li_(0.19)Sm_(0.14))TiO_3 ceramics

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2010年第3期29卷 243-247页

作者： lu yin LI Haitao LI Qian ZHANG Boping Department of Mechanical Engineering Henan Polytechnic Institute Nanyang 473009 China School of Materials Science and Engineering Henan University of Science and Technology Luoyang 471003 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The effects of ZnO-B2O3 （ZB2） on the sintering behavior and microwave dielectric properties of （Ca0.254Li0.19Sm0.14）TiO3 ceramics were investigated. The densities of the specimens reached the maximum value by adding 3 wt.% ZB2 and then decreased. The sintering temperature of the specimens was lowered from 1300 to 1100℃ without degradation of the microwave dielectric properties. The （Ca0.254Li0.19Sm0.14）TiO3＋ 3 wt.% ZB2 sintered at 1100℃ for 3 h showed good microwave dielectric properties, εr= 108.2, Qf= 6545 GHz, and rf= 6.5 ppm/℃, respectively, indicating that ZB2 was an effective sintering aid to improve the densification and microwave dielectric properties of （Ca0.254Li0.19Sm0.14）TiO3 ceramics.

关键词： microwave dielectric properties densification ceramics sintering behavior

Hot Deformation Behavior and Processing Map of a Cu-Bearing 2205 Duplex Stainless Steel

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2019年第12期32卷 1537-1548页

作者： Tong Xi lu yin Chun-Guang Yang Ke Yang Institute of Metal Research Chinese Academy of Sciences

The hot deformation behavior and processing map of Cu-bearing 2205 duplex stainless steel(2205-Cu DSS)were investigated at temperatures of 950-1150℃ and strain rates of 0.01-10 s^-*** effects of Cu addition and different deformation parameters on deformation behavior were,respectively,characterized by analyzing flow curves,constitutive equations and *** results indicated that the shapes of flow curves strongly depended on the volume fraction of two *** deformed at low strain rate,DRV in ferrite was prompted with increase in the temperature and was further developed to continuous *** high strain rate,flow localization preferentially occurred in ferrite at low deformation temperature due to the strain partitioning and relatively less fraction of *** activation energy for 2205-Cu DSS was 452 kJ/mol and was found to connect with the variation of strain,strain rate and deformation *** optimum hot deformation parameters for 2205-Cu DSS were obtained in the temperature range of 1100-1150℃ and strain rate range of 0.1-1 s^-1 with a peak power dissipation efficiency of 41%.Flow localization was the main way to lead to flow ***,the Cu-rich precipitates were generated within a few ferrite grains when deformed at temperature lower than 1000℃.The interaction between dislocations and Cu-rich precipitates at high strain rate,as well as the limited DRV in ferrite and DRX in austenite,contributed to the complex microstructure and flow behavior.

关键词： Cu-bearing duplex stainless steel Hot deformation Processing map Dynamic recrystallization Dynamic recovery

Numerical investigation on leakage and rotordynamic performance of the honeycomb seal with swirl-reverse rings

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第6期35卷 87-100页

作者： Chengjing GU Wanfu ZHANG Xingchen YANG Kexin WU lu yin School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China

Honeycomb seals are a crucial component to restrict the leakage flow and improve system stability for the turbomachines and *** this work,the leakage and rotordynamic performance of honeycomb seals with the Swirl-Reverse Ring(SRR)is predicted by employing the approach of Computational Fluid Dynamics(CFD)and the multifrequency whirling model *** results show that the positive preswirl flow and circumferential velocity can be effectively weakened for the honeycomb seal as SRR is *** obtained results also suggest that the direct stiffness,direct damping,and effective stiffness will not reduce,for the honeycomb seal is introduced to ***,the honeycomb seal with SRR can significantly reduce the crosscoupled stiffness and remarkably enhance the effective ***,the absolute value of negative tangential force acting on the rotor surface significantly increased for the honeycomb seal introduced ***,the whirling velocity of the rotor would be *** phenomenon would be conducive to improve the stability of the ***,the performance of SRR can be further enhanced when SRR possesses a smaller bending angle,and a higher arrangement density and height.

关键词： Computational Fluid Dynamics(CFD) Honeycomb seal Leakage Rotordynamic performance Stability Swirl-Reverse Ring(SRR)

Rotordynamic characteristics prediction for scallop damper seals using computational fluid dynamics

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第8期35卷 92-106页

作者： Wanfu ZHANG lu yin Li YANG Haoyang TIAN Chun LI School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Electric Power Research Institute of State Grid Shanghai Municipal Electric Power CompanyShanghai 200437China

Enhancing damping characteristic is one of the effective methods to solve the instability problem of the rotor *** three-dimensional numerical analysis model of scallop damper seal was established,and the effects of inlet pressures,preswirl ratios,rotational speeds,interlaced angles and seal cavity depths on the rotordynamic characteristics of scallop damper seal were studied based on dynamic mesh method and multi-frequencies elliptic whirling *** show that the direct stiffness of the scallop damper seal increases with decreasing inlet pressure and increasing rotational speed and cavity *** the seal cavity is interlaced by a certain angle,which shows positive direct *** effective damping of the scallop damper seal increases with the increasing inlet pressure,the decreasing preswirl ratio and the rotational speed and cavity *** exists an optimal interlaced angle to maximize the effective damping and the system *** leakage of the scallop damper seal is significantly reduced with decreasing inlet *** preswirl will reduce the leakage flowrate,and the rotational speed has a slight effect on the leakage *** leakage of the scallop damper seal decreases with increasing seal cavity depth.

关键词： Computational Fluid Dynamics(CFD) Effective damping Rotordynamic characteristics Scallop damper seal Stability