Acquisition,Pointing and Tracking System for Shipborne Space Laser Communication without Prior Information

A space laser communication acquisition,pointing and tracking(APT)system based on the beacon laser is designed without prior information.And then,a new target scanning method and a pointing and tracking algorithm are proposed.The target scanning mode is the round-trip triangular wave scanning,and it means that scanning track of the PAN-TILT platform follows the triangular wave repeatedly.For the pointing and tracking algorithm,the beacon laser is used as the auxiliary aiming light source.The position of the beacon laser in the viewfield of the complementary metal oxide semiconductor(CMOS)camera is calculated by the centroid algorithm.In order to realize the target tracking,the joint control method of the angle control and the angular velocity control is used.The simulation and experimental results show that the APT system can achieve full coverage scanning in the scanning area and capture the target in one scanning cycle successfully.After capturing the PAN-TILT platform,the pointing and tracking algorithm can track the PAN-TILT platform quickly and accurately,and the tracking accuracy is up to 0.22 mrad.

Method of Carrier Acquisition and Track for HAPS

This paper emphasizes on the characteristics and schemes of carrier acquisition and track in high dynamic and high information-rate situation. Carrier acquisition model is analyzed theoretically and the design princi-ple of carrier acquisition is deduced and described clearly. An algorithm for carrier acquisition in high dy-namic and high information-rate situation is provided. This paper also proves the validity of the algorithm and design scheme in high dynamic and high information-rate situation.

Machine-vision-based acquisition,pointing,and tracking system for underwater wireless optical communications

Due to the proliferation of underwater vehicles and sensors,underwater wireless optical communication(UWOC)is a key enabler for ocean exploration with a strong reliance on short-range bandwidth-intensive communications.A stable optical link is of primary importance for UWOC.A compact,low-power,and low-cost acquisition,pointing,and tracking(APT)system is proposed and experimentally demonstrated to realign the optical link within 0.04 s,even when the UWOC transmitter and receiver are in relative motion.The system successfully achieves rapid auto-alignment through a 4 m tap water channel with a relatively large number of bubbles.Furthermore,the required minimum illumination value is measured to be as low as7.1 lx,implying that the proposed APT scheme is robust to dim underwater environments.Meanwhile,mobility experiments are performed to verify the performance of the APT system.The proposed system can rapidly and automatically align moving targets in complex and unstable underwater environments,which can potentially boost the practical applications of UWOC.

Continuous-Wave Interference Mitigation for Acquisition Method in Unified Carrier TT&C Systems

An interference mitigation for acquisition method,based on both energy center and spectrum symmetry detection,has been proposed as a possible solution to the problem of signal acquisition susceptibility to continuous-wave interference(CWI)in unified carrier telemetry,tracking,and command(TT&C)systems.With subcarrier modulation index as a priori condition,the existence of CWI is determined by comparing the energy center with the symmetric center.In the presence of interference,the interference frequency point is assumed and culled;sequentially,the spectral symmetry is used to verify whether the signal acquisition is realized.Theoretical analysis,simulations,and experimental results demonstrate that the method can realize the acquisition of the main carrier target signal with an interference-to-signal ratio of 31 dB,which represents an improvement over the existing continuous-wave interference mitigation for acquisition methods.

Neutron Flux Signal Acquisition from Plant Instrumentation Channel of Research Reactor for Reactivity Calculation

A design for instantaneous neutron flux signal acquisition system is being carried out for reactivity measurement of the nuclear research reactor. It is a computer-based digital data acquisition system that can perform continuous monitor and measurement of reactivity inserted into or removed from the research reactor. The acquisition system accomplishes with two major parts. The first part is an interfacing PCI based data acquisition card and the corresponding driver software intending to on-line acquisition of neutron flux signals from plant instrumentation channel. The second part incorporates the high-level Visual Basic real time program, indigenously developed for computation of reactivity by the solution of neutron point kinetic equations and other relevant functional modules like input file logging, reactivity calculation, graphics demonstration etc.

Research and Implementation of Beidou-3 Satellite Multi-Band Signal Acquisition and Tracking Method

A new acquisition and tracking method is proposed for signal processing under the new signal system structure of Beidou-3 navigation satellite system(BDS-3). By starting with the analysis of the characteristics and signal structure of the new signal, the local replica of the ranging code and the study of the characteristics of the ranging code are completed, which proves that the method in this paper can be used in the subsequent acquisition and tracking process. The fast Fourier transformation(FFT) search based on longer coherence time and the adaptive phase-frequency switching carrier tracking loop are proposed for signals in different modulation modes. The actual signal of Beidou-3 satellite is sampled by local experiment, and the acquisition and tracking of the Beidou-3 satellite multi-band signal is finally completed. The tracking results verify the feasibility of the proposed acquisition and tracking method.

Maximum Power Point Tracking Based on Improved Kepler Optimization Algorithm and Optimized Perturb&Observe under Partial Shading Conditions

Under the partial shading conditions(PSC)of Photovoltaic(PV)modules in a PV hybrid system,the power output curve exhibits multiple peaks.This often causes traditional maximum power point tracking(MPPT)methods to fall into local optima and fail to find the global optimum.To address this issue,a composite MPPT algorithm is proposed.It combines the improved kepler optimization algorithm(IKOA)with the optimized variable-step perturb and observe(OIP&O).The update probabilities,planetary velocity and position step coefficients of IKOA are nonlinearly and adaptively optimized.This adaptation meets the varying needs of the initial and later stages of the iterative process and accelerates convergence.During stochastic exploration,the refined position update formulas enhance diversity and global search capability.The improvements in the algorithmreduces the likelihood of falling into local optima.In the later stages,the OIP&O algorithm decreases oscillation and increases accuracy.compared with cuckoo search(CS)and gray wolf optimization(GWO),simulation tests of the PV hybrid inverter demonstrate that the proposed IKOA-OIP&O algorithm achieves faster convergence and greater stability under static,local and dynamic shading conditions.These results can confirm the feasibility and effectiveness of the proposed PV MPPT algorithm for PV hybrid systems.

In situ nanobubble sizing by visualization particle tracking and image-based dynamic light scattering

A novel method combining visualization particle tracking with image-based dynamic light scattering was developed to achieve the in situ and real-time size measurement of nanobubbles(NBs).First,the in situ size distribution of NBs was visualized by dark-field microscopy.Then,real-time size during the preparation was measured using image-based dynamic light scattering,and the longitudinal size distribution of NBs in the sample cell was obtained in a steady state.Results show that this strategy can provide a detailed and accurate size of bubbles in the whole sample compared with the commercial ZetaSizer Nano equipment.Therefore,the developed method is a real-time and simple technology with excellent accuracy,providing new insights into the accurate measurement of the size distribution of NBs or nanoparticles in solution.

Comprehensive review and performance evaluation of maximum power point tracking algorithms for photovoltaic system

A photovoltaic array is environmentally friendly and a source of unlimited energy generation.However,it is presently a costlier energy generation system than other non-renewable energy sources.The main reasons are seasonal variations and continuously changing weather conditions,which affect the amount of solar energy received by the solar panels.In addition,the non-linear characteristics of the voltage and current outputs along with the operating environment temperature and variation in the solar radiation decrease the energy conversion capability of the photovoltaic arrays.To address this problem,the global maxima of the PV arrays can be tracked using a maximum power point tracking algorithm(MPPT)and the operating point of the photovoltaic system can be forced to its optimum value.This technique increases the efficiency of the photovoltaic array and minimizes the cost of the system by reducing the number of solar modules required to obtain the desired power.However,the tracking algorithms are not equally effective in all areas of application.Therefore,selecting the correct MPPT is very critical.This paper presents a detailed review and comparison of the MPPT techniques for photovoltaic systems,with consideration of the following key parameters:photovoltaic array dependence,type of system(analog or digital),need for periodic tuning,convergence speed,complexity of the system,global maxima,implemented capacity,and sensed parameter(s).In addition,based on real meteorological data(irradiance and temperature at a site located in Addis Ababa,Ethiopia),a simulation is performed to evaluate the performance of tracking algorithms suitable for the application being studied.Finally,the study clearly validates the considerable energy saving achieved by using these algorithms.

Maximum Power Point Tracking Control Using Neural Networks for Stand-Alone Photovoltaic Systems

The employment of maximum power point tracking techniques in the photovoltaic power systems is well known and even of immense importance. There are various techniques to track the maximum power point reported in several literatures. In such context, there is an increasing interest in developing a more appropriate and effective maximum power point tracking control methodology to ensure that the photovoltaic arrays guarantee as much of their available output power as possible to the load for any temperature and solar radiation levels. In this paper, theoretical details of the work, carried out to develop and implement a maximum power point tracking controller using neural networks for a stand-alone photovoltaic system, are presented. Attention has been also paid to the command of the power converter to achieve maximum power point tracking. Simulations results, using Matlab/Simulink software, presented for this approach under rapid variation of insolation and temperature conditions, confirm the effectiveness of the proposed method both in terms of efficiency and fast response time. Negligible oscillations around the maximum power point and easy implementation are the main advantages of the proposed maximum power point tracking (MPPT) control method.

Quadrature Kalman Filter(QKF) and Reduced Quadrature Kalman Filter(R-QKF)in Ballistic Target Tracking

Recently there have been researches about new efficient nonlinear filtering techniques in which the nonlinear filters generalize elegantly to nonlinear systems without the burdensome lineafization steps. Thus, truncation errors due to linearization can be compensated. These filters include the unscented Kalman filter （UKF）, the central difference filter （CDF） and the divided difference filter （DDF）, and they are also called Sigma Point Filters （SPFs） in a unified way. For higher order approximation of the nonlinear function. Ito and Xiong introduced an algorithm called the Gauss Hermite Filter, which is revisited in [5]. The Gauss Hermite Filter gives better approximation at the expense of higher computation burden, although it＇s less than the particle filter. The Gauss Hermite Filter is used as introduced in [5] with additional pruning step by adding threshold for the weights to reduce the quadrature points.

Verification of Dosimetric and Positional Accuracy of Dynamic Tumor Tracking Intensity Modulated Radiation Therapy

Purpose: We performed both, dosimetric and positional accuracy verification of dynamic tumor tracking (DTT) intensity modulated radiation therapy (IMRT), with the Vero4DRT system using a moving phantom (QUASAR respiratory motion platform;QUASAR phantom) and system log files. Methods: The QUASAR phantom was placed on a treatment couch. Measurement of the point dose and dose distribution was performed for conventional IMRT, with the QUASAR phantom static and moving;for DTT IMRT, this was performed with the phantom moving for pyramid shaped, prostate, paranasal sinus, and pancreas targets. The QUASAR phantom was driven by a sinusoidal signal in the superior-inferior direction. Furthermore, predicted positional errors induced by the Vero4DRT system and mechanical positional errors of the gimbal head, were calculated using the system log files. Results and Conclusion: For DTT IMRT, the dose at the evaluation point was within 3% compared with the verification plan, and the dose distribution in the passing rates of γ was 97.9%, with the criteria of 3% dose and 3 mm distance to agreement. The position error calculated from the log files was within 2 mm, suggesting the feasibility of employing DTT IMRT with high accuracy using the Vero4DRT system.

Research on the MPPT of Photovoltaic Power Generation Based on Improved WOA and P&O under Partial Shading Conditions

Partial shading conditions(PSCs)caused by uneven illumination become one of the most common problems in photovoltaic(PV)systems,which can make the PV power-voltage(P-V)characteristics curve show multi-peaks.Traditional maximum power point tracking(MPPT)methods have shortcomings in tracking to the global maximum power point(GMPP),resulting in a dramatic decrease in output power.In order to solve the above problems,intelligent algorithms are used in MPPT.However,the existing intelligent algorithms have some disadvantages,such as slow convergence speed and large search oscillation.Therefore,an improved whale algorithm(IWOA)combined with the P&O(IWOA-P&O)is proposed for the MPPT of PV power generation in this paper.Firstly,IWOA is used to track the range interval of the GMPP,and then P&O is used to accurately find the MPP in that interval.Compared with other algorithms,simulation results show that this method has an average tracking efficiency of 99.79%and an average tracking time of 0.16 s when tracking GMPP.Finally,experimental verification is conducted,and the results show that the proposed algorithm has better MPPT performance compared to popular particle swarm optimization(PSO)and PSO-P&O algorithms.

Probabilistic Global Maximum Power Point Tracking Algorithm for Continuously Varying Partial Shading Conditions on Autonomous PV Systems

A photovoltaic (PV) string with multiple modules with bypass diodes frequently deployed on a variety of autonomous PV systems may present multiple power peaks under uneven shading. For optimal solar harvesting, there is a need for a control schema to force the PV string to operate at global maximum power point (GMPP). While a lot of tracking methods have been proposed in the literature, they are usually complex and do not fully take advantage of the available characteristics of the PV array. This work highlights how the voltage at operating point and the forward voltage of the bypass diode are considered to design a global maximum power point tracking (GMPPT) algorithm with a very limited global search phase called Fast GMPPT. This algorithm successfully tracks GMPP between 94% and 98% of the time under a theoretical evaluation. It is then compared against Perturb and Observe, Deterministic Particle Swarm Optimization, and Grey Wolf Optimization under a sequence of irradiance steps as well as a power-over-voltage characteristics profile that mimics the electrical characteristics of a PV string under varying partial shading conditions. Overall, the simulation with the sequence of irradiance steps shows that while Fast GMPPT does not have the best convergence time, it has an excellent convergence rate as well as causes the least amount of power loss during the global search phase. Experimental test under varying partial shading conditions shows that while the GMPPT proposal is simple and lightweight, it is very performant under a wide range of dynamically varying partial shading conditions and boasts the best energy efficiency (94.74%) out of the 4 tested algorithms.

IoT Enabled Microgrid Framework Using a Novel Dispersal Diffusion Artificial Neural Network Controller for PV Systems and Wind Energy to Minimize Electrical Faults

A system based on a PV-Wind will ensure better efficiency and flexibility using lower energy production.Today,plenty of work is being focussed on Doubly Fed Induction Generators(DFIG)utilized in wind energy systems.DFIG is found to be the best option in the Wind Energy Conversion Systems(WECS)to mitigate the issues caused by power converters.In this work,a new Artificial Neural Network(ANN)is proposed with the Diffusion and Dispersal strategy that works on Maximum Power Point Tracking(MPPT)along with Wind Energy Conversion System(WECS)to minimize electrical faults.The controller focus was not just to increase performance but also to reduce damage owing to any phase to phase fault or Phase to phase to ground fault.To ensure optimal MPPT for the proposed WECS,ANN achieves the optimal PI controller parameters for the indirect control of active and reactive power of DFIG.The optimal allocation and size of the DGs within the distributed system and for MPPT control are obtained using a population of agents.The generated solutions are evaluated and on being successful,the agents test their hypothesis again to create a positive feedback mechanism.Simulations are carried out,and the proposed IoT framework efficiency indicates performance improvement and faster recovery against faults by 9 percent for phase to ground fault and by 7.35 percent for phase to phase fault.

Analysis of Maximum PowerPoint Tracking (MPPT) Adaptability in Inverters of the Three-Phase Photovoltaic Systems Integrated into the Electrical Grid of Congo-Brazzaville

This paper investigates the adaptability of Maximum Power Point Tracking (MPPT) algorithms in single-stage three-phase photovoltaic (PV) systems connected to the grid of Congo-Brazzaville and compares the attributes of various conventional, significance and novelty of controller system of the proposed of method and improved Incremental Conductance algorithms, Perturbation and Observation Techniques, and other Maximum Power Point Tracking (MPPT) algorithms in normal and partial shading conditions. Performance evaluation techniques are discussed on the basis of the dynamic parameters of the PV system although the control of this structure is relatively advanced technology but the conversion efficiency is difficult to improve due to increase in transformation series. The single stage topology has a simple topology with high reliability and efficiency because of high power consumption, but control algorithm is more complex because of its power convert main circuit a new strategy is being developed. This paper describes a method for maximum power point tracking (MPPT) in the single-stage and three single-phase PV grid-connected system. In the paper, the nonlinear output characteristics of the PV including I-V & P-V are obtained in changed solar insulations or temperature based on MATLAB, and the MPPT algorithm which is based on the P & O algorithm method, compared with Incremental Conductance, is also described, a dimensioning of the impedance adapter for better stabilization. A comparison SPWM and SVPWM control methods in the case of a grid connection applied to the electrical grid of Republic of Congo and their influences on the dynamic performance of the system and their impact in reducing the harmonic rate for better injection into the grid. The simulation model of three single-phase PV grid-connected system is built, and simulation results show the MPPT algorithm has excellent dynamic and static performances, which verifies the Incremental Conductance is effective for MPPT in the single-stage and three single-phase PV grid-connected system.

Broadband seismic illumination and resolution analyses based on staining algorithm

Seismic migration moves reflections to their true subsurface positions and yields seismic images of subsurface areas. However, due to limited acquisition aperture, complex overburden structure and target dipping angle, the migration often generates a distorted image of the actual subsurface structure. Seismic illumination and resolution analyses provide a quantitative description of how the above-mentioned factors distort the image. The point spread function （PSF） gives the resolution of the depth image and carries full information about the factors affecting the quality of the image. The staining algorithm establishes a correspondence between a certain structure and its relevant wavefield and reflected data. In this paper, we use the staining algorithm to calculate the PSFs, then use these PSFs for extracting the acquisition dip response and correcting the original depth image by deconvolution. We present relevant results of the SEG salt model. The staining algorithm provides an efficient tool for calculating the PSF and for conducting broadband seismic illumination and resolution analyses.

Design and simulation of the ATP system considering the advanced targeting angle in quantum positioning system

A compensation implementation scheme of the advanced targeting process based on the fine tracking system is proposed in this paper.Based on the working process of the quantum positioning system(QPS)and its acquisition,tracking and pointing(ATP)system,the advanced targeting subsystem of the ATP system is designed.Based on six orbital parameters of the quantum satellite Mozi,the advanced targeting azimuth angle and pitch angle are transformed into the dynamic tracking center of the fine tracking system in the ATP system.The deviation of the advanced targeting process is analyzed.In the Simulink,the simulation experiment of the ATP system considering the deviation compensation of the advanced targeting is carried out,and the results are analyzed.

The Point Approach and the Phrase Approach to Vocabulary Learning

As is known to all, vocabulary acquisition plays an essential role in English learning. However, it was supposed very difficult to many Chinese learners. For the reason that so many kinds of approaches exists in the real life, English learners are always do not know which one is suitable and more effective. To solve this problem, the paper will analyze two approaches (point approach and phrase approach) for you.

AAM-Candide结合的快速表情动画合成模型

针对现有的算法在表情动画合成中自动化程度不高、生成效果不理想的问题,本文提出了一种基于AAM-Candide结合的快速表情动画合成模型。首先利用Candide-3算法获取面部表情参数-AU,并通过确定人脸的Candide-3模型来计算AU,将参数提取问题转化为一个非刚体的人脸跟踪问题,然后利用彩色图对人脸关键点进行2D定位,通过上下限规范实现Candide-3和三维数据点云之间的对应点集。实例仿真结果表明,本文提出的改进算法,对惊讶、悲伤、嘟嘴、开心等4种表情得到了较好的动画合成效果。