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2019

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Articles 1081 - 1110 of 2060

Full-Text Articles in Computer Engineering

In-Cylinder Process Simulation Of Swashplate Revoloving Cylinder Piston Engine Based On Fluid-Structure Interaction, Li Xin, Chengshi Yang, Peng Bo Jan 2019

In-Cylinder Process Simulation Of Swashplate Revoloving Cylinder Piston Engine Based On Fluid-Structure Interaction, Li Xin, Chengshi Yang, Peng Bo

Journal of System Simulation

Abstract: Using dynamic mesh technology, In-cylinder working process of the engine is detailedly designed in this article regarding the new swashplate revolving cylinder piston engine. We establish the numeral simulation model of the engine working process based on fluid-structure interaction, the pressure and temperature distribution of the In-cylinder gas in the six thermal process is obtained, and the temperature distribution of the hot end components is presented. The results show that the working process of the engine is reasonably organized. The biggest thermal load appears in the intake flow process. The wall temperature of the gas side is lower …


Numerical Simulation Of Thermal Properties Of Active Phased Array Antenna, Wang Yong, Ting Lu, Longwen Wu, Changwu Xiong, Weng Xia, Ping'an Du Jan 2019

Numerical Simulation Of Thermal Properties Of Active Phased Array Antenna, Wang Yong, Ting Lu, Longwen Wu, Changwu Xiong, Weng Xia, Ping'an Du

Journal of System Simulation

Abstract: The grid priority modeling and multi-level meshing techniques are applied to analyze the thermal properties of the active phased array antenna with the micro/mini channels cooling method for simplifying modeling process, reducing the mesh quantity and saving the cost of computation effectively. The multi-level meshing technique can refine the mesh near the boundary of the complex components significantly without changing the mesh quantity in the model, which improves the mesh’s quality obviously. Through the thermal simulation and experiment measurement of the antenna, the temperature and pressure field are obtained. It is proved that the addressed approach can …


Abnormal Behavior Detection Via Super-Pixels Time Context Feature, Chen Ying, Dandan He Jan 2019

Abnormal Behavior Detection Via Super-Pixels Time Context Feature, Chen Ying, Dandan He

Journal of System Simulation

Abstract: In order to accurately locate the abnormal behavior, an anomaly detection method based on time context features of super-pixels is proposed. For feature representation, the video frames are firstly segmented into super-pixels. The super-pixels of foreground are then selected according to their pixel ratios of foreground. Super-pixels matching adjacent frames are selected based on the gray-level histogram and the information of location to enhance the temporal context of super-pixel features. The statical value of multilayer histogram of optical flow of matched super-pixels are taken as the feature for detection. In the phase of detection, the sparse combination learning algorithm …


An Anti-Occlusion Adaptive Particle Filtering Algorithm, Li Ju, Mingwei Cao, Yu Ye, Xia Yu, Lifan Zhou Jan 2019

An Anti-Occlusion Adaptive Particle Filtering Algorithm, Li Ju, Mingwei Cao, Yu Ye, Xia Yu, Lifan Zhou

Journal of System Simulation

Abstract: Considering the influence of local occlusion on particle filter tracking algorithm, an anti occlusion adaptive particle filtering algorithm is proposed. It adopts a rectangle as the tracking window, and uses the K mean clustering algorithm to complete particle clustering in resampling, and then obtains the particle subgroup. It estimates the final state according to particles subgroups, and modifies the tracking window. When the area changes more than 5%, the tracking window maintains the same as the one in last frame. Otherwise, the tracking window will change according to the size of moving object, which is a self-adaptation process. At …


Scenario Computing For Analysis Of Deep Uncertainty Systems, Liu Yi, Gangqiao Wang, Zhipeng Wu, Zhenqiang Fan, Yongqiang Chen Jan 2019

Scenario Computing For Analysis Of Deep Uncertainty Systems, Liu Yi, Gangqiao Wang, Zhipeng Wu, Zhenqiang Fan, Yongqiang Chen

Journal of System Simulation

Abstract: A method of scenario computing is developed for modeling systems with deep uncertainty. The method consists three complementary parts: hybrid modelling, diverse computing, and interactive validation. Hybrid modelling is to dynamically develop models with merging historical knowledges and observed information. Diversity computation is to simulate multiple plausible scenarios about system future. Interactive validation helps scenario computing process being on the right way instead of deviating. Two cases are provided in this paper applying scenario computing, one is earthquake and the other is driving and transportation. The results show good performance of scenario computing method in modeling uncertainty systems.


Mathematical Modeling And Simulation Of Hydraulic Gauge Control System, Weigang Li, Guilin Tao Jan 2019

Mathematical Modeling And Simulation Of Hydraulic Gauge Control System, Weigang Li, Guilin Tao

Journal of System Simulation

Abstract: On the basis of hydraulic valve control cylinder model and combining with the structure and load characteristics of the hydraulic gauge control system (HGC), a “flow linearization” model for HGC was presented and the shortcomings of the model in analyzing the dynamic characteristics of HGC were pointed out. In view of the characteristics of the large load variation range of HGC and according to the principle of “load compensation”, the flow correction coefficient and the related transfer function were analyzed and deduced, and the mathematical model of HGC based on “load compensation” was established. Combined with a practical …


Simple Chaotic Circuit Based On Memristance Function With Real Exponents Power, Xiaohong Zhang, Yanli Qi Jan 2019

Simple Chaotic Circuit Based On Memristance Function With Real Exponents Power, Xiaohong Zhang, Yanli Qi

Journal of System Simulation

Abstract: The simplest chaotic circuit contains only three circuit elements: a linear passive inductor, a linear passive capacitor and a nonlinear active memristor. In the design of memristors, power of memristance function polynomial with integral exponents is commonly used. On this basis, a general memristor is designed, of which the memristance function polynomial uses power with real exponents, a simple chaotic system is constructed based on the designed memristor. The influence of integral exponents, real exponents and linear parameters on dynamic behaviors is investigated, and chaotic behaviors are analyzed qualitatively using Lyapunov exponents. The Matlab and Multisim simulation results show …


Simulation Research Of Closed Control System For Equipment Operation And Maintenance With Parts Inventory System, Li Bing, Wang Xing, Xuan Hua, Xueyuan Wang Jan 2019

Simulation Research Of Closed Control System For Equipment Operation And Maintenance With Parts Inventory System, Li Bing, Wang Xing, Xuan Hua, Xueyuan Wang

Journal of System Simulation

Abstract: The highly reliable equipment operation and maintenance system is very important to enterprise’s safety production. The control system for equipment operation and maintenance with a parts inventory system is generally discussed. The proposed system is composed of a parts inventory subsystem, an equipment operation subsystem and an equipment maintenance subsystem as parallel and series form. And the control system belongs to a multi-level closed loop system. The system is a kind of discrete event dynamic system. So it is difficult to be described with traditional mathematical analysis methods. The multi-class closed control system simulation model is established with Simulink …


Error Estimation For Material Simulation Data Based On Hybrid Learning Algorithm, Wang Juan, Xiaoyu Yang, Zongguo Wang, Ren Jie, Xushan Zhao Jan 2019

Error Estimation For Material Simulation Data Based On Hybrid Learning Algorithm, Wang Juan, Xiaoyu Yang, Zongguo Wang, Ren Jie, Xushan Zhao

Journal of System Simulation

Abstract: In order to obtain high quality material simulation data from Density Functional Theory material calculation software package, a modeling method based on BP neural network was proposed to build model estimating the error of material simulation data. A novel hybrid algorithm combining simple particle swarm optimization algorithm that excludes speed item with BP algorithm, also referred to tsPSO-BP, was proposed to optimize the connection weights of the BP neural network. The hybrid learning algorithm not only makes use of strong global searching ability of the PSO, but also strong local searching ability of the BP algorithm. The BP …


Research On Fault-Tolerant Flight Control Computer System Based On Dynamic Reconfiguration, Xiaozhe Sun, Zongji Chen, Yongliang Gu Jan 2019

Research On Fault-Tolerant Flight Control Computer System Based On Dynamic Reconfiguration, Xiaozhe Sun, Zongji Chen, Yongliang Gu

Journal of System Simulation

Abstract: The fault-tolerant Fly-By-Wire flight control systems of four advanced aircrafts of Boeing and Airbus series (B777, B787, A340 and A380) were analyzed and compared. The disadvantages needed to be improved were explored in terms of software reliability and system reconfiguration of Boeing and Airbus Fly-By-Wire flight control systems. A novel redundant fault-tolerant flight control computer (FCC) system was presented. The proposed FCC scheme was qualitatively and quantitatively compared with redundant FCC of Boeing and Airbus. The three schemes' reliability was modelled and evaluated through the hierarchical hybrid modelling method. The conclusions are obtained as follows: the proposed …


Multi-Dimension Proportion-Differential Nonlinear Pilot Model And Simulation Application, Weian Jiang Jan 2019

Multi-Dimension Proportion-Differential Nonlinear Pilot Model And Simulation Application, Weian Jiang

Journal of System Simulation

Abstract: For better simulated study of pilot’s accident avoidance ability and pilot induced oscillation (PIO) characteristic of a man-aircraft close loop system, a method of “physiology-psychology-physiology” is presented to divide pilot models into three parts of input(signal), processing(decision making) and output(action), and a new multi-dimension proportion-differential nonlinear pilot model (MPDNLPM) is presented also. Simulated study is performed by simulated control of an aircraft pitch control model under backside tracking status for carrier landing. Conclusion: 1) The control performance of the man-aircraft system is slightly better than an ideal proportional control. 2) PIO is possible for well-trained pilot. 3) Proper anticipation, …


Simulation Research On Predictive Wavelet Neural Network Intelligent Control System, Jingwei Liu, Zhou Rui, Zhao Hui, Minling Zhu, Xianghua Meng, Yuhao Zhang Jan 2019

Simulation Research On Predictive Wavelet Neural Network Intelligent Control System, Jingwei Liu, Zhou Rui, Zhao Hui, Minling Zhu, Xianghua Meng, Yuhao Zhang

Journal of System Simulation

Abstract: In order to realize control parameters online tuning and optimizing applications in the high risk and high pollution environment, vector time series prediction based intelligent control methods are proposed, which are combined autoregressive moving average vector time series predictive method and wavelet neural network method. Based on theoretical and comparative research: feasibility, stability, better dynamic characteristics, less steady-state error of the proposed methods are verified. A comparative simulation platform for the above intelligent control system is provided. Stability guarantee method of the above new methods is given.


Hybrid Decoding Algorithm For Low-Density Parity-Check Codes, Guowei Qu, Xiaoping Song Jan 2019

Hybrid Decoding Algorithm For Low-Density Parity-Check Codes, Guowei Qu, Xiaoping Song

Journal of System Simulation

Abstract: A hybrid decoding algorithm for low-density parity-check (LDPC) codes based on the soft-decision iterative decoding method and the erasure decoding method is proposed. If a decoding error is detected when the maximum iteration number of the soft-decision iterative decoding is reached, a decision is made on each bit whether it is zero or one or an erasure according to the cumulative reliability of the bit in the iterative process. Then the decision result is decoded with erasure decoding. Simulation results on random LDPC codes with moderate length indicate that the proposed hybrid decoding algorithm outperforms the traditional soft-decision iterative …


Trust Evaluation Model Based On Fuzzy Set And D-S Evidence Theory In Wireless Sensor Network, Zhiping Zhou, Xiaoxiao Zhao, Nannan Shao Jan 2019

Trust Evaluation Model Based On Fuzzy Set And D-S Evidence Theory In Wireless Sensor Network, Zhiping Zhou, Xiaoxiao Zhao, Nannan Shao

Journal of System Simulation

Abstract: A trust evaluation model based on fuzzy set and D-S evidence in wireless sensor network is proposed. Considering security requirements and energy consumption, three typical trust factors are defined to calculate node’s direct trust which is for fuzzy classification by using fuzzy set theory. Fuzzy membership function is the basic belief function of the D-S evidence theory. Indirect trust is obtained from neighbor nodes’ recommendations, the direct trust and indirect trust are fused according to Dempster combination rule after being amended with weight. The effective combination of identity-based cryptosystem and the trust management mechanism improve the security …


Forestry Felling & Cultivation Machine Virtual Training System Based On Unity3d, Bowen Cheng, Yili Zheng, Qingqing Huang, Jinhao Liu Jan 2019

Forestry Felling & Cultivation Machine Virtual Training System Based On Unity3d, Bowen Cheng, Yili Zheng, Qingqing Huang, Jinhao Liu

Journal of System Simulation

Abstract: A forestry felling & cultivation machine virtual training system based on Unity3D was developed. The models of forestry felling & cultivation machine were built up using 3dsMAX with the assistance of SolidWorks based on a forestry felling & cultivation machine. The models of forestry felling & cultivation machine and trees were imported into Unity3D to create a virtual operating environment. Each part of forestry felling & cultivation machine needs to be processed for the establishment of paternity in accordance with the simulation, the corresponding mathematical model was established to simulate the motion of the manipulator based on the analysis …


Parallel Pattern Recognition Of Leak Current Data Using Spark-Knn, Li Li, Yongli Zhu, Yaqi Song Jan 2019

Parallel Pattern Recognition Of Leak Current Data Using Spark-Knn, Li Li, Yongli Zhu, Yaqi Song

Journal of System Simulation

Abstract: With the rapid development of smart grid, the status monitoring data of power grid equipment increase exponentially and gradually form the big data. Traditional computing architectures are no longer to meet the demand of computing performance. This paper explores how Spark and Cloud computing can accelerate performance of missive insulator leak current data pattern recognition. The Parallel KNN (k-Nearest Neighbor) algorithm is designed and implemented by using Spark and Aliyun E-MapReduce cloud computing platform. The results from experiments show that the performance of Spark-KNN is 2.97 times of MapReduce-KNN and gains acceleration of 8.8 times. The experimental results confirm …


Stress Distribution Formula Of Threads Casing Joint Under Symmetrical Load, Tong Hua, Xiaohong Tang, Xiaohua Zhu, He Huan, Haoran Tao Jan 2019

Stress Distribution Formula Of Threads Casing Joint Under Symmetrical Load, Tong Hua, Xiaohong Tang, Xiaohua Zhu, He Huan, Haoran Tao

Journal of System Simulation

Abstract: While itis difficult tomeasure thestress distribution of casing threads underground without calculation by finite element method. Here assumes a deformation compatibility factor Ux, use an initial calculation to represent the thread stress, f(x)=f0Ux, and applythe ABAQUS finite element software to calculate the stress distribution of the threads under different symmetrical loads. Obtain the expressions of Ux by curve fitting, and get the threads stress calculation formula to provide an intuitive, fast and accurate method of calculation for the site. Providea theoretical reference for development and manufacture of casing …


Overview Of Multi-Agents Modeling And Simulation For Underwater Unmanned Combat Systems, Hongtao Liang, Fengju Kang, Yanfang Fu Jan 2019

Overview Of Multi-Agents Modeling And Simulation For Underwater Unmanned Combat Systems, Hongtao Liang, Fengju Kang, Yanfang Fu

Journal of System Simulation

Abstract: Military UUV is developing toward the direction of intellectualization and coordination of multi-UUV system. It is composed of complex underwater unmanned system (UUS) with changeable underwater environment and complex combat mission. Multi-agents (MAS) modeling technology has become the mainstream method to study this kind of complex system. The development and characteristics of UUS are briefly and comprehensively reviewed. The latest developments of MAS theory are systematically summarized, and MAS modeling and simulation technology for multi-UUV cooperative combat system (MUCCS) are analyzed. A novel MAS theory method, that is immune agent interactive network (IAIN), is proposed, which combines the modeling …


Numerical Simulation Of Borehole Stability In Underbalanced Drilling Coal Seam, Yumei Li, Su Zhong, Zhang Tao, Delong Zhang, Liwei Yu, Si Na Jan 2019

Numerical Simulation Of Borehole Stability In Underbalanced Drilling Coal Seam, Yumei Li, Su Zhong, Zhang Tao, Delong Zhang, Liwei Yu, Si Na

Journal of System Simulation

Abstract: According to the formation parameters of No.3 coal seam in the Qinshui Basin, Shanxi Province, considering the interaction between seepage and deformation in the borehole wall of coal seam, using the finite element method for establishing the stable elastoplastic numerical model of the borehole in coal seam,the variation of pore pressure near the wellbore wall with the seepage time and the effect of time delay on wellbore stability under underbalanced drilling condition were studied. The variation law of maximum displacement and maximum plastic deformation around borehole wall with bottom pressure were analyzed. The simulation results show that there …


Permanent Magnet Synchronous Motor Multi-Parameter Identification Based On Improved Salp Swarm Algorithm, Mengqiu Wang, Wang Yan, Zhicheng Ji Jan 2019

Permanent Magnet Synchronous Motor Multi-Parameter Identification Based On Improved Salp Swarm Algorithm, Mengqiu Wang, Wang Yan, Zhicheng Ji

Journal of System Simulation

Abstract: Since the multi-parameter identification of permanent magnet synchronous motor (PMSM) has slow speed and low accuracy, a parameter identification method based on the improved salp swarm algorithm was proposed in this paper. The algorithm firstly adopted the self-adaptive evaluation-move strategy and neighborhood optimum guide strategy based Von Neumann topology to update the position of followers twice, which strengthened information cooperation in the population and accelerated the convergence rate of parameter identification. Secondly, the algorithm used the opposition-based learning strategy to perturb the population position with a certain mutation probability, that avoided local optimum and misconvergence of the parameters. The …


Improvement Of Grey Target Algorithm And Its Application In Assessment Of Marine Gas Turbine, Tongqing Wang, Mei Shan, Xiaobo Li, Jiajie Liu Jan 2019

Improvement Of Grey Target Algorithm And Its Application In Assessment Of Marine Gas Turbine, Tongqing Wang, Mei Shan, Xiaobo Li, Jiajie Liu

Journal of System Simulation

Abstract: In the modern shipbuilding industry, gas turbines are increasingly becoming the main power supply devices for ships with their good overall performance. The assessment of their overall performance is very important in the development and introduction of gas turbines. By using the grey target theory, a comprehensive gas turbine performance evaluation model is constructed and the grey target method can easily deal with the evaluation problem which has the characteristics of "small amount of data, lean information, and uncertainty". By discussing the influence of distinguishing coefficient in the algorithm, a method for determining the value of the distinguishing coefficient …


Impact Of Attractiveness And Influence Of Information On Cascade Size Distribution, Dong Jian, Bin Chen, Liu Liang, Chuan Ai, Zhang Fang, Xiaogang Qiu Jan 2019

Impact Of Attractiveness And Influence Of Information On Cascade Size Distribution, Dong Jian, Bin Chen, Liu Liang, Chuan Ai, Zhang Fang, Xiaogang Qiu

Journal of System Simulation

Abstract: The distribution of the cascade size can capture the distribution of popularity of a social network. Numerous studies have shown that the cascade size distribution follows fat-tail distributions, including power-law distribution and bimodal distribution; The underlying characteristic of this highly skewed distribution lacks quantitative experimental analysis. Based on the heterogeneous stochastic information dissemination model, namely the SVRF model, this paper examines the impact of the information attractiveness and influence on the cascade size distribution through lots of computational experiments. We find that when the mean value of the information influence and attractiveness is small, the cascade sizes follow …


Simulation Analyzing For Drawing Up Methodology Of Cooperative Train Working Diagram And Route Allocation Plan, Zhou Yan Jan 2019

Simulation Analyzing For Drawing Up Methodology Of Cooperative Train Working Diagram And Route Allocation Plan, Zhou Yan

Journal of System Simulation

Abstract: The quality of the train diagram directly affects the efficiency of the transport operation and management. Though the inadequacies of computer drawing train working diagram were reviewed, an integrated drawing up methodology of train diagram and train route allocation plan was put forward to optimize the allocation of resources, based on the interaction relationship of train diagram and train route allocation plan. On that basis, the overall state transition adjustment algorithm, which consists of the “full timetable” result and collaborative model route allocation plan, was also proposed. Finally, the prototype system framework based on .NET was described, and the …


Three-Dimensional Model Of Magnetostrictive Force Sensor Considering Stress Coupling And Experimental Research, Li Bo, Jiabin Yang, Shu Liang, Penghui Li, Wu Hong Jan 2019

Three-Dimensional Model Of Magnetostrictive Force Sensor Considering Stress Coupling And Experimental Research, Li Bo, Jiabin Yang, Shu Liang, Penghui Li, Wu Hong

Journal of System Simulation

Abstract: Considering the brittleness of normal magnetostrictive and piezoelectric materials, a new magnetostrictive force sensor is proposed, in which Galfenol alloy is taken as the sensing element. Considering the anisotropy of Galfenol, three-dimensional magneto-mechanical coupled model is presented on the basis of electromagnetic and mechanical governing equation. The nonlinear magnetization behavior of Galfenol is described by employing the discrete energy-averaged model. The coupling of the magnetization model and the structural model is implemented with the PDE weak form equations. The model is solved by using the weak form module of Comsol Multiphysics. Simulation results show that both field and stress …


Design Of Fault Tolerant Control Visual Simulation System For Flying Wing Aircrafts, Shaojie Zhang, Qingkai Meng Jan 2019

Design Of Fault Tolerant Control Visual Simulation System For Flying Wing Aircrafts, Shaojie Zhang, Qingkai Meng

Journal of System Simulation

Abstract: A visual simulation platform based on Qt Quick was designed with respect to the simulation about fault tolerant control for flying wing aircrafts. Aircraft mathematical model and control law were developed using Simulink. Man-machine interface was developed based on Qt Quick to inject fault to Simulink model, load control law, setting up the simulation parameters and process, the interface can monitor and display graphically the key parameters to test and verify fault tolerant control laws. FlightGear visual engine was driven by MATLAB to achieve real-time visual flight simulation and the aircraft were showed in 3-D model. Baidu Map’s API …


Multi-Constraint Service Selection Based On Decomposition Of Global Qos, Fang Chen, Jindong Wang, Hengwei Zhang, Wang Na Jan 2019

Multi-Constraint Service Selection Based On Decomposition Of Global Qos, Fang Chen, Jindong Wang, Hengwei Zhang, Wang Na

Journal of System Simulation

Abstract: With the rapid growth of Web services in cloud computing environment, users make new demands on dynamic service composition, that quickly selects composite service which can meet multi-constraints. According to the demand, a multi-constraint service selection method based on decomposition of global QoS was proposed. A new cultural genetic algorithm was designed to decompose the global QoS constraints, and services were filtered by combining with the functional constraints between candidate services. An adaptive replacement strategy was used to dynamically adjust QoS constraint boundaries, so as to ensure the most appropriate composite service obtained by local selection. Experimental results show …


Research On Impact Performance Of Layer-Number Of 2024 Aerospace Aluminum Alloy Immobilized Target Against Bird Strike, Jianxin Xu, Jiajun Yuan, Yunfei Deng Jan 2019

Research On Impact Performance Of Layer-Number Of 2024 Aerospace Aluminum Alloy Immobilized Target Against Bird Strike, Jianxin Xu, Jiajun Yuan, Yunfei Deng

Journal of System Simulation

Abstract: In order to investigate the anti-penetration performance of target plate of the same thickness under different number of layers, a model of SPH(Smoothed Particle Hydrodynamics) cylindrical bird bullet to impact 2024 aerospace aluminum alloy Lagrange target is established by using the AUTODYN finite element software. The thickness of target is 1 mm, 2 mm, 3 mm and 4 mm, 1 mm and 2 mm target plate is divided into single and double, 3 mm target plate is divided into single, double and three layers, 4 mm target plate is divided into single, double and four layers. …


Fault Co-Simulation Of Fuel Regulator In A Certain Type Of Turbofan Engine, Wei Xiang, Benwei Li, Xinyi Yang, Xingbo Wang Jan 2019

Fault Co-Simulation Of Fuel Regulator In A Certain Type Of Turbofan Engine, Wei Xiang, Benwei Li, Xinyi Yang, Xingbo Wang

Journal of System Simulation

Abstract: A co-simulation method for fuel regulator fault diagnosis in a certain type of turbofan engine is performed, which consists of AMEsim Model of main fuel control system and Simulink Model of aero-engine. The AMEsim Model of main fuel system and Simulink Model of aero-engine are built and their accuracy is validated by experiments and the engine’s operating data, respectively. The co-simulation model based on the main fuel control system and the aero-engine is proposed through the interface of AMEsim and Simulink software. The typical faults and obviation methods are simulated by the co-simulation model. The research shows that the …


Study On Design And Simulation Of Pyramidal Horn Antenna, Denghua Li, Fangfang Ji, Hao Cui, Wenbai Chen Jan 2019

Study On Design And Simulation Of Pyramidal Horn Antenna, Denghua Li, Fangfang Ji, Hao Cui, Wenbai Chen

Journal of System Simulation

Abstract: In order to study the low-profile panel antenna that works in Ku band (12.25’12.75GHz), a high-gain Pyramidal horn antenna is designed as the unit of low-profile panel antenna. To meet dual polarization, it was taken into account that the radiation aperture of antenna unit has symmetric structure. Thus the feed waveguide is designed into a square waveguide. The proposed antenna is designed, simulated and optimized for antenna gain with HFSS (High Frequency Structure Simulator) software. Simulated results show that: in the Ku band, the reflection coefficient is less than -21dB; and the VSWR …


Assessment And Verification Of Code-Carrier Coherence On Bds, Dongxia Li, Fuhan Song, Ruihua Liu Jan 2019

Assessment And Verification Of Code-Carrier Coherence On Bds, Dongxia Li, Fuhan Song, Ruihua Liu

Journal of System Simulation

Abstract: In order to verify code-carrier coherence on BeiDou Navigation Satellite System (BDS), the monitoring and assessment system of code-carrier coherence on BDS is designed. Code-Carrier Divergence (CCD) monitor is designed to detect the anomaly status of ionosphere, and based on the detection results, ionosphere delay error is eliminated by using Divergence-Free Smoothing (DFree) or Ionosphere-Free Smoothing (IFree) separately. The values of integer ambiguity are calculated based on tri-frequency ambiguity decomposition model, and the cycle slip is detected by using tri-frequency pseudorange code and combination of carrier phase. Assessment and verification of code-carrier coherence can be conducted. It is …