Design and Analysis of Terminal Guidance Law for Kinetic Interceptors based on Pulse Engine

A new terminal guidance law is proposed based on a solid propellant pulse engine and an improved proportional navigation method to address the terminal guidance issue for kinetic interceptors.On this basis,the start-stop curve of the pulse motor during the terminal guidance process is designed,along with its start-up logic.The effectiveness of the proposed guidance strategy is verified through simulation.

On a Flexible Loan Repayment Method Depending on Borrower's Asset with an Early Termination Clause

Aiming at the problem that the asset’s fluctuation influences the borrower’s repayment ability,a loan with a new and flexible repayment method is designed,which depends on the asset value of the borrower.The repayment method can reduce the loan default probability,but it causes the uncertainty of the pay off time.Because the repayment term is related to the regular repayment amount in this method,a boundary for the regular repayment amount is set up in order to avoid too long repayment term.This will balance the benefit of borrowers and lenders and improve the applicability of this method.By establishing a mathematical model of the residual value of the loan,this model can be transformed into an initial-boundary problem of a partial differential equation.The analytic solution and the expected time to pay off the loan are obtained.Finally,numerical analysis are shown.

Adaptive Backstepping Terminal Sliding Mode Control Method Based on Recurrent Neural Networks for Autonomous Underwater Vehicle

The trajectory tracking control problem is addressed for autonomous underwater vehicle(AUV) in marine environ?ment, with presence of the influence of the uncertain factors including ocean current disturbance, dynamic modeling uncertainty, and thrust model errors. To improve the trajectory tracking accuracy of AUV, an adaptive backstepping terminal sliding mode control based on recurrent neural networks(RNN) is proposed. Firstly, considering the inaccu?rate of thrust model of thruster, a Taylor’s polynomial is used to obtain the thrust model errors. And then, the dynamic modeling uncertainty and thrust model errors are combined into the system model uncertainty(SMU) of AUV; through the RNN, the SMU and ocean current disturbance are classified, approximated online. Finally, the weights of RNN and other control parameters are adjusted online based on the backstepping terminal sliding mode controller. In addition, a chattering?reduction method is proposed based on sigmoid function. In chattering?reduction method, the sigmoid function is used to realize the continuity of the sliding mode switching function, and the sliding mode switching gain is adjusted online based on the exponential form of the sliding mode function. Based on the Lyapu?nov theory and Barbalat’s lemma, it is theoretically proved that the AUV trajectory tracking error can quickly converge to zero in the finite time. This research proposes a trajectory tracking control method of AUV, which can e ectively achieve high?precision trajectory tracking control of AUV under the influence of the uncertain factors. The feasibility and e ectiveness of the proposed method is demonstrated with trajectory tracking simulations and pool?experi?ments of AUV.

Improved edge lightweight YOLOv4 and its application in on-site power system work

A“cloud-edge-end”collaborative system architecture is adopted for real-time security management of power system on-site work,and mobile edge computing equipment utilizes lightweight intelligent recognition algorithms for on-site risk assessment and alert.Owing to its lightweight and fast speed,YOLOv4-Tiny is often deployed on edge computing equipment for real-time video stream detection;however,its accuracy is relatively low.This study proposes an improved YOLOv4-Tiny algorithm based on attention mechanism and optimized training methods,achieving higher accuracy without compromising the speed.Specifically,a convolution block attention module branch is added to the backbone network to enhance the feature extraction capability and an efficient channel attention mechanism is added in the neck network to improve feature utilization.Moreover,three optimized training methods:transfer learning,mosaic data augmentation,and label smoothing are used to improve the training effect of this improved algorithm.Finally,an edge computing equipment experimental platform equipped with an NVIDIA Jetson Xavier NX chip is established and the newly developed algorithm is tested on it.According to the results,the speed of the improved YOLOv4-Tiny algorithm in detecting on-site dress code compliance datasets is 17.25 FPS,and the mean average precision(mAP)is increased from 70.89%to 85.03%.

Trajectory tracking and obstacle avoidance method for robots based on fast terminal sliding mode

For accurate trajectory tracking and obstacle avoidance in finite time of a nonholonomic mobile robot,a trajectory tracking controller based on global fast terminal sliding mode method is proposed,which has the advantages of chattering-free and adjustable convergence time.First of all,the kinematics model of the robot is established in mobile carrier coordinates.Secondly,the global structure including terminal attractor and exponential convergence of the fast terminal sliding mode trajectory tracking controller is proved by Lyapunov stability theory,ensuring that the trajectory and heading angle tracking error converges to a smaller zero range in finite time.Finally,the artificial potential field obstacle avoidance method is introduced to make the robot not only track the reference trajectory strictly,but also avoid the obstacles.The simulation results show that the proposed method can achieve a stable tracking control in finite time for a given reference trajectory.

Terminal fertility control: Clients’ own reason for the choice of the contraceptive method

Background: The prevalence of contraceptive use has increased worldwide due to the development and introduction of modern contraceptives and the establishment of organized family planning programs. In Nigeria, there is a very slow rise in contraceptive use prevalence, resulting in high fertility rate. Generally contraceptive is either used for birth spacing, or for the purpose of terminal fertility control to limit the number of children, and the choice of method for this purpose varies. Aims and Objectives: To determine the contraceptive methods of choice among clients seeking terminal fertility control, and their reasons for the choice of such methods. Materials and Methods: A cross-sectional study of clients attending the family planning clinic of Ladoke Akintola University of Technology Teaching hospital over a period of twenty-four months, between July, 2009 and June, 2011. All clients who had completed their family, and wanted a contraceptive method to limit their family size filled the semi-structured questionnaire after giving their informed consent. Clients’ own reasons for the choice of the particular contraceptive method were grouped, entered into SPSS work sheet, and analyzed using SPSS version 17. Result: There were five hundred and ninety-two new contraceptive method acceptors during the study period, of which 264 (44.6%) were for terminal fertility control. Progestogen-only injectable contraceptive was the method of choice for terminal fertility control by 145 (54.9%) of the clients, while 85 (32.2%) made intrauterine contraceptive device (copper-T) their method of choice, and the least chosen method was female surgical sterilization (2, 0.8%). Ease of administration, satisfaction with previous use, long duration of action, and husband’s preference were the reasons for the choice of the methods. Conclusion: There is awareness of terminal fertility control in Nigeria, especially in the southwestern region of the country, and this may be responsible for the decreasing prevalence of grandmultiparity in the region. However, reversible contraceptive method is the preferred option for this purpose.

Real- Time Color Enhancement Method Used for Intelligent Mobile Terminals

In certain environments and under some conditions, the video images taken by the intelligent mobile video phones seem dark, and the colors are not bright or saturated enough.This paper presents an adaptive method to enhance the video image brightness visualization and the color performance depending on the certain hardware property and function parameters. The experimental results prove that this method can enhance the colors and the contrast of the video images, based on the estimated quality feature values of each frame, without using the extra Digital Signal Processor (DSP).

Performance of the suspension method in large cross-section shallow-buried tunnels

Large cross-section tunnel construction induces ground surface settlements, potentially endangering both subterranean projects and nearby above-ground structures. A novel tunnel construction method, known as the suspension method,is introduced in this paper to mitigate surface settlement. The suspension method employs vertical tie rods to establish a structural connection between the initial tunnel support system and the surface steel beam, thereby exerting effective control settlements. To analyze the performance of the proposed method, systematic numerical simulations were conducted based on the practical engineering of Harbin Subway Line 3. The surface settlement and vault settlement characteristics during construction are investigated. The results show a gradual increment in both surface and vault settlement throughout the construction process, culminating in a stabilized state upon the completion of construction.In addition, compared to the double-side drift method and the Cross Diaphragm Method(CRD) method, the suspension method can obviously reduce the surface settlement and vault settlement. Moreover, the surface settlements and the axial force of tie rods were continuously monitored during the construction process at the trial tunnel block.These specific monitoring measurements are illustrated in comparison to numerical analysis results. The monitored results show great agreement with the numerical predictions, confirming the success of the project. This research can serve as a valuable practical reference for similar projects, offering insights and guidance for addressing ground surface settlements and enhancing construction safety in the domain of large cross-section tunneling.

A Logical Treatment of Non-Termination and Program Behaviour

Can the semantics of a program be represented as a single formula? We show that one formula is insufficient to handle assertions, refinement or slicing, while two formulae are sufficient: A (S) , defining non-termination, and B (S), defining behaviour. Any two formulae A and B will define a corresponding program. Refinement is defined as implication between these formulae.

基于元胞自动机的航站楼离港车道边停车容量评估研究

航站楼车道边是旅客实现陆空转换的关键节点,其规模对陆侧交通的正常运行有着至关重要的作用。针对航站楼离港车道边送客车辆的个体行为,基于元胞自动机提出一种改进型离港车道边停车容量仿真模型并利用实测数据对模型的准确性进行验证,最后利用文中模型分析了不同停车方式及停靠时间对停车容量的影响。试验结果表明,仿真结果与实测数据基本一致,可用于评估离港车道边停车容量;在车道边规模不变的前提下,竖向停车方式可以显著增加车道边停车容量;两种停车方式的车道边停车容量都随停靠时间的增加而减小。

互联网软件产品移动端UI设计方法研究

由于移动端UI设计缺乏更加完善的理论作为指导,导致互联网软件产品的设计质量效果较差,为此提出互联网软件产品移动端UI设计方法。确定图像元素与文字元素为移动端UI设计中的主要视觉元素,通过构建移动端UI界面视觉注意力划分模型,明确各视觉元素对于整个UI界面的重要程度,自动编排图像元素与文字元素,完成互联网软件产品移动端UI界面的设计。实验表明,UI界面设计效果可以满足用户需求,验证了设计方法的可行性。

移动终端驱动的地铁列车舒适度评价方法

针对传统列车舒适度研究在地铁列车舒适性长期服役监测方面的局限性,提出了一种基于移动终端的地铁列车舒适度评价方法。通过调研移动终端集成的传感器种类确定了地铁列车舒适度的影响因素为振动、噪声以及照度。结合问卷调查法和层次分析法确定各个因素对地铁列车舒适性影响的权重系数,综合现有标准和模拟实验建立影响因素的评价模型并制订了对应的评价标准,进而确定地铁列车舒适度评价方法,并将该评价方法集成到自主开发的移动终端的APP上,实现了列车舒适度数据的大范围采集。为了客观验证该方法的可行性,在地铁线路实验中采集专业测量仪器、移动终端和可穿戴设备的实验数据并进行分析。分析结果表明:列车平稳运行状态下,通过移动终端采集的振动、噪声和照度舒适度评价值的相对误差不超过5%、15%和18%;在两种工况下噪声舒适度评价值占总评价值的67.8%和76.5%,因此对列车舒适性影响程度最大的是噪声;基于提出方法的地铁列车舒适度评价结果与心率变异性频域指标(LF、HF和LF/HF)的分析结果趋于一致,客观地验证了该评价方法的可行性。移动终端驱动的地铁列车舒适度评价方法可为地铁列车舒适性大范围监测和长期服役性能演化分析提供新的方法和思路。

SVC与发电机励磁的逆推Terminal滑模协调控制

设计了一种静止无功补偿器与发电机励磁的逆推Terminal滑模协调控制器,采用逆推法逐步构造李亚普洛夫函数,不确定参数用自适应律替换,最后一步加入Terminal滑模面,使相关变量能够在有限时间内收敛到零。针对单机无穷大系统的仿真结果表明,所设计的逆推Terminal滑模协调稳定控制器能够快速阻尼功率振荡,有效提高电力系统的暂态稳定性并可维持机端电压恒定。

基于灰色模型的局部放电智能感知终端评估方法研究

随着电网运维部门对在线监测和智能化运检的重视,各种监测功能的智能终端逐步普及,针对投入使用的智能传感器,迫切需要一个成熟的平台和评估方法对智能终端的各项核心的性能指标进行校核和评估。以局部放电智能感知终端灵敏度、线性度、数据稳定性、可靠性(环境适应性和EMC(electro magnetic compatibility))和电池功耗寿命5项核心的指标为研究对象,提出每个指标的评估方法。最后结合熵值法与灰色理论对局部放电智能感知终端评估建立量化评价体系,给出案例分析。通过8个智能终端的案例,利用熵值法赋权,通过灰色关联分析法计算各个指标的关联系数,最终计算得8个智能终端综合得分,其中最高评价得分为77.1%,最低得分为44.8%,分数差异明显。基于灰色模型的定量评分可以有效的进行局部放电智能感知终端评估。文中的研究结果为局部放电智能感知终端设备的参数和性能指标量化评价提供了指导。

Terminal滑模变结构励磁控制设计及仿真研究

基于Terminal滑模变结构控制,提出了一种新的励磁控制器设计策略。给出了其设计过程,计算了其到达时间,证明了其稳定性。该励磁控制策略以微分几何精确反馈线性化为理论基础,可以推广到多机系统的分散励磁控制中。以线性最优励磁控制器为参照,利用一典型单机无穷大系统,进行了多种扰动下的仿真校验。仿真结果验证了所提励磁控制策略的稳定性和鲁棒性,此外,还发现该控制策略能明显提高系统的电压、功角、频率稳定性。

考虑资源弹性配置的配电网保护控制终端协同任务分配方法

随着新型电力系统的发展,利用智能终端处理愈发复杂的配电网保护控制任务时,对资源供给与需求的平衡要求越来越高。因此,文中提出一种考虑资源弹性配置的配电网保护控制终端(protect and control intelligent terminal,PCIT)协同任务优化分配方法。首先,阐述多终端协同的技术架构,并建立基于容器的PCIT的弹性资源模型、任务处理模型。其次,提出双层模型用于优化保护控制任务在终端间的协同分配、资源的弹性调度,并利用隐枚举法对该模型进行求解,从而充分发挥任务处理时资源的灵活性,提升任务处理性能。最后,算例验证了文中所提方法的可行性与先进性,各智能终端计算资源的占用率降低约28.85%,任务平均处理延时减少约4.12%。

引信用非制冷快响应长波红外敏感技术

为了解决引信近场探测对非制冷快响应长波红外敏感技术的需求,开展光子型材料在长波红外敏感技术方面的应用研究。采用熔体外延技术生长出的铟砷锑厚膜单晶通过工艺制备,形成一种可在非制冷条件下截止波长延伸到11μm的光子型红外探测器。通过对器件的性能测试及末敏弹扫描平台的应用表明,该器件在响应波段和响应时间两方面可有效提升红外引信的探测能力。

考虑自动驾驶仪延迟的非线性最优末制导方法

针对过载受限和自动驾驶仪延迟等条件下的非线性最优末制导指令在线生成方法进行研究。首先,基于庞特里亚金极大值原理,建立了目标静止的非线性最优末制导问题的最优性条件,并利用饱和函数将过载约束嵌入最优性条件。其次,应用参数化方法使得通过数值积分即可快速生成满足最优性条件的飞行轨迹数据集。然后,利用该数据集训练神经网络,使其拟合弹-目相对运动状态到最优制导指令的映射关系,实现过载约束下制导指令的毫秒量级在线生成。针对自动驾驶仪的延迟响应,通过微分补偿法估计神经网络下一时刻输出的制导指令以实现快速跟踪。最后,仿真结果表明,本文所提出方法针对静止目标与小机动目标都能够在线生成最优制导指令。

直接驱动XY平台全局快速Terminal滑模控制

针对永磁直线同步电机驱动XY平台系统的非线性、不确定性及轮廓误差模型复杂等问题,设计了基于等效误差法的全局快速Terminal滑模轮廓控制器.运用等效误差法建立容易计算的直接驱动XY平台非线性等效误差模型;采用全局快速Terminal滑模控制方法设计直接驱动XY平台轮廓控制器.该控制方法可以促使系统在有限时间内迅速收敛到平衡状态,同时能抑制负载扰动和参数不确定性对系统性能的影响.仿真结果表明,所设计的轮廓控制器使直接驱动XY平台具有了较高的轮廓加工精度和较强的鲁棒性.

一种非线性系统积分Terminal滑模的控制系统设计

针对一种非线性动态系统,提出了一种新的非奇异的快速Terminal滑模控制系统设计方法.首先,在分析Terminal滑模设计方法的基础上,为了进一步加速状态在滑模运动的速度,提出了一种快速Terminal滑模,避免了传统Terminal滑模奇异问题,并给出了状态收敛到平衡状态的时间范围.其次,针对含有不确定性的非线性系统,结合反演法设计了有限时间稳定的快速Terminal滑模控制系统.最后,利用数字仿真验证了提出的积分Terminal滑模控制系统设计的有效性.