Sliding mode control and Lyapunov based guidance law with impact time constraints

This paper analyses the issue of impact time control of super-cavitation weapons impact fixed targets which mainly refer to the ships or submarines who lost power, but still have combat capability. Control over impact time constraints of guidance law(ITCG) is derived by using sliding mode control(SMC) and Lyapunov stability theorem. The expected impact time is realized by using the notion of attack process and estimated time-to-go to design sliding mode surface(SMS). ITCG contains equivalent and discontinuous guidance laws, once state variables arrive at SMS,the equivalent guidance law keeps the state variables on SMS,then the discontinuous guidance law enforces state variables to move and reach SMS. The singularity problem of ITCG is also analyzed. Theoretical analysis and numerical simulation results are given to test the effectiveness of ITCG designed in this paper.

Fuzzy sliding mode control guidance law with terminal impact angle and acceleration constraints

In this paper, a novel fuzzy sliding mode control（FSMC） guidance law with terminal constraints of miss distance, impact angle and acceleration is presented for a constant speed missile against the stationary or slowly moving target. The proposed guidance law combines the sliding mode control algorithm with a fuzzy logic control scheme for the lag-free system and the first-order lag system. Through using Lyapunov stability theory, we prove the sliding surface converges to zero in finite time. Furthermore, considering the uncertain information and system disturbances, the guidance gains are on-line optimized by fuzzy logic technique. Numerical simulations are performed to demonstrate the performance of the FSMC guidance law and the results illustrate the validity and effectiveness of the proposed guidance law.

Management of Control Impacts Based on Maximizing the Spread of Influence

The choice of fulcrums for control of socio-economic systems represented by direc ted weighted signed graphs is a topic of current interest.This article proposes a new method for identifying nodes of impact and influential nodes,which will provide a guaranteed positive system response over the growth model.The task is posed as an optimization problem to maximize the ratio of the norms of the accumulated increments of the growth vector and the exogenous impact vector.The algorithm is reduced to solving a quadratic programming problem with nonlinear restrictions.The selection of the most effective vertices is based on the cumulative gains of the component projections onto the solution vector.Numerical examples arc provided to illustrate the effectiveness of the proposed method.

Impact dynamics analysis of free-floating space manipulator capturing satellite on orbit and robust adaptive compound control algorithm design for suppressing motion

The impact dynamics, impact effect, and post-impact unstable motion sup- pression of free-floating space manipulator capturing a satellite on orbit are analyzed. Firstly, the dynamics equation of free-floating space manipulator is derived using the sec- ond Lagrangian equation. Combining the momentum conservation principle, the impact dynamics and effect between the space manipulator end-effector and satellite of the cap- ture process are analyzed with the momentum impulse method. Focusing on the unstable motion of space manipulator due to the above impact effect, a robust adaptive compound control algorithm is designed to suppress the above unstable motion. There is no need to control the free-floating base position to save the jet fuel. Finally, the simulation is proposed to show the impact effect and verify the validity of the control algorithm.

Acute histopathological responses and long-term behavioral outcomes in mice with graded controlled cortical impact injury

While animal models of controlled cortical impact often display short-term motor dysfunction after injury, histological examinations do not show severe cortical damage. Thus, this model requires further improvement. Mice were subjected to injury at three severities using a Pin-Point^(TM)-controlled cortical impact device to establish secondary brain injury mouse models. Twenty-four hours after injury, hematoxylin-eosin staining, Fluoro-Jade B histofluorescence, and immunohistochemistry were performed for brain slices. Compared to the uninjured side, we observed differences of histopathological findings, neuronal degeneration, and glial cell number in the CA2 and CA3 regions of the hippocampus on the injured side. The Morris water maze task and beam-walking test verified long-term(14–28 days) spatial learning/memory and motor balance. To conclude, the histopathological responses were positively correlated with the degree of damage,as were the long-term behavioral manifestations after controlled cortical impact. All animal procedures were approved by the Institutional Animal Care and Use Committee at Shanghai Jiao Tong University School of Medicine.

Water Hyacinth Control by Glyphosate Herbicide and Its Impact on Water Quality

The aim of this study was to evaluate the herbicide glyphosate under aquatic environment conditions, in a controlled and closed experimental field, in the management of water hyacinth (Eichhornia crassipes) in reservoirs. Twenty reservoirs (polyethylene water tanks) with storage capacity of 1000 liters were used, without water flow and without evapotranspired water replacement (worst case), being 04 for each treatment. The adult plants were placed in the water tanks to provide 90% surface occupation of the reservoir. Five treatments with four repetitions were considered, being: 1) Reservoir colonized by water hyacinth without control;2) Reservoir colonized by water hyacinth, controlled by glyphosate;3) Reservoir colonized by water hyacinth, controlled by freezing;4) Reservoir without water hyacinth and glyphosate application and 5) Reservoir without water hyacinth and no glyphosate application. The glyphosate herbicide was used at the highest recommended dose, 7.0 L·ha-1 or 3360 g of acid equivalent per ha, applied using carbon dioxide precision equipment (backpack sprayer), providing a flow rate of 200 L·ha-1. The water samples were collected at the time of application, 6, 12, 18 and 24 hours after application and also at 2, 4, 8, 16, 32 and 64 days after application, in the morning, always at the same time, also between 8 and 9 h. The method used for determination of residues was by high performance liquid chromatography (HPLC) and mass spectrometry with a mass selective detector. Low concentrations of glyphosate and aminomethylphosphonic acid (AMPA) were found in both reservoirs that received application of the product. The half-life of glyphosate in water to the reservoirs with water hyacinth was 11 days and in the reservoirs without water hyacinth was 21 days. The results show a low potential of environmental impact of glyphosate use in the control of water hyacinth in reservoirs.

A hybrid proportional navigation based two-stage impact time control guidance law

To improve applicability and adaptability of the impact time control guidance(ITCG) in practical engineering, a twostage ITCG law with simple but effective structure is proposed based on the hybrid proportional navigation, namely, the pureproportional-navigation and the retro-proportional-navigation.For the case with the impact time error less than zero, the first stage of the guided trajectory is driven by the retro-proportionalnavigation and the second one is driven by the pure-proportionalnavigation. When the impact time error is greater than zero, both of the stages are generated by the pure-proportional-navigation but using different navigation gains. It is demonstrated by twoand three-dimensional numerical simulations that the proposed guidance law at least has comparable results to existing proportional-navigation-based ITCG laws and is shown to be advantageous in certain circumstances in that the proposed guidance law alleviates its dependence on the time-to-go estimation, consumes less control energy, and adapts itself to more boundary conditions and constraints. The results of this research are expected to be supplementary to the current research literature.

Calculation of impact factor of vibrator oscillation in offset printing based on fuzzy controller and genetic algorithm

In the inking system of an offset printing press,a vibrator roller distributes ink not only in the circumferential direction but also in the axial direction.In the control process,if ink amount is determined only by the dot area coverage without considering the impact of vibrator roller's oscillation,the printing colour quality will be reduced.This paper describes a method of calculating the impact factor of vibrator roller' s oscillation.First,the oscillation performance is analyzed and sample data of impact factor is got.Then,a fuzzy controller used for the calculation of the impact factor is designed,and genetic algorithm is used to optimize membership functions and obtain the fuzzy control rules automatically.This fuzzy controller can be used to calculate impact factors for any printing condition,and the impact factors can be used for ink amount control in printing process and it is important for higher printing colour quality and lowering ink and paper waste.

Integrated guidance and control design for missile with terminal impact angle constraint based on sliding mode control

Aimed at the guidance requirements of some missiles which attack targets with terminal impact angle at the terminal point,a new integrated guidance and control design scheme based on variable structure control approach for missile with terminal impact angle constraint is proposed.First,a mathematical model of an integrated guidance and control model in pitch plane is established,and then nonlinear transformation is employed to transform the mathematical model into a standard form suitable for sliding mode control method design.A sufficient condition for the existence of linear sliding surface is given in terms of linear matrix inequalities（LMIs）,based on which the corresponding reaching motion controller is also developed.To verify the effectiveness of the proposed integrated design scheme,the numerical simulation of missile is made.The simulation results demonstrate that the proposed guidance and control law can guide missile to hit the target with desired impact angle and desired flight attitude angle simultaneously.

Analysis on the Impacts of Precise Poverty Alleviation on Folk Customs and Control Measures

The promotion of precise poverty alleviation in poverty-stricken areas will inevitably lead to changes in local folk customs.The economic development may bring about greater development of folk customs,and may also lead to qualitative changes in folk customs.This paper mainly introduced the impact of the precise poverty alleviation on the folk customs.Based on the analysis,it came up with pertinent control measures,to better combine the folk customs with precise poverty alleviation measures,to promote common development of economy and culture in poverty stricken areas.

Impact angle control over composite guidance law based on feedback linearization and finite time control

The impact angle control over guidance(IACG) law against stationary targets is proposed by using feedback linearization control(FLC) and finite time control(FTC). First, this paper transforms the kinematics equation of guidance systems into the feedbackable linearization model, in which the guidance law is obtained without considering the impact angle via FLC. For the purpose of the line of sight(LOS) angle and its rate converging to the desired values, the second-order LOS angle is considered as a double-integral system. Then, this paper utilizes FTC to design a controller which can guarantee the states of the double-integral system converging to the desired values. Numerical simulation illustrates the performance of the IACG, in contrast to the existing guidance law.

基于冲能吸能平衡效应的冲击地压巷道分级支护研究

冲击地压是煤炭开采过程中发生的一种动力灾害,主要是由积聚在煤岩中的弹性变形能突然急剧释放造成的,约90%发生在巷道中。巷道冲击破坏不仅与冲击能量直接相关,还与冲击距离远近紧密相关,提出能距比的概念,即冲击震源释放能量与其至巷道距离的比值。根据冲击地压动静载叠加机制和冲能吸能平衡理论,综合考虑冲击震源能距比量级、巷道破坏程度、支护构件吸能、弱结构吸能等特性,建立了巷道围岩冲击矿震稳定性控制模型,分析了冲能、吸能的构成和计算过程,搭建了冲击地压能级与巷道支护强度之间的对应关系,确定了“四高锚网+”为主导技术的煤矿巷道防冲抗震支护体系。根据能距比量级大小,将冲击地压巷道支护安全可靠性分为P1~P4级别,分级对应采取不同支护强度的“四高锚网+”组合支护技术。“四高”锚网支护可对应能距比为102量级的无冲击巷道,“四高锚网+1”(O型钢棚、吸能防冲单元架、围岩弱结构)对应能距比为103量级的冲击地压,“四高锚网+2”对应能距比为104量级的冲击地压,“四高锚网+3”对应能距比为105量级的冲击地压,106及以上量级的冲击危险必须停产、撤人远场处理。结合工程实例进行了巷道防冲支护方案和参数设计,初步验证了理论研究成果的可行性和实用性。研究成果可为我国煤矿冲击地压巷道支护理论研究和工程实践提供一定的参考指导。

Dynamical behaviour of a controlled vibro-impact system

In this paper, we give a controlled two-degree-of-freedom （TDOF） vibro-impact system based on the damping control law, and then investigate the dynamical behaviour of this system. According to numerical simulation, we find that this control scheme can suppress chaos to periodic orbit successfully. Furthermore, the feasibility and the robustness of the controller are confirmed, separately. We also find that this scheme cannot only suppress chaos, but also generate chaos in this system.

有限视场下的攻击时间和角度多约束制导律

针对精确打击任务存在导引头视场受限这一过程约束的制导问题,提出了一种考虑视场限制以及攻击角度和时间多种约束的制导律.首先,在以比例导引项实现精确命中的基础上,利用最优控制理论,采用弹目距离加权控制能耗形式的指标函数,设计了攻击角度控制项,并推导了相应的剩余飞行时间解析预测表达式.其次,基于最优误差动力学方法,设计了攻击时间相关的控制项,保证了攻击时间误差的有限时间收敛.同时,针对导引头视场有限的问题,分析了各控制项对前置角收敛性的影响,利用特定的限制函数确保前置角在整个制导过程中始终处于有效视场内,并给出了前置角的有界性及收敛性证明.数学仿真结果验证了所提出制导律对多约束制导问题的有效性.

食用菌虫害防控研究进展

食用菌产业在国内发展迅速,已经成为一类重要的经济作物。但在食用菌栽培中虫害频繁发生,给食用菌生产造成了严重的损失。本文从食用菌害虫种类概况、栽培环境对食用菌害虫种群发生的影响和食用菌虫害综合防控研究等方面总结了国内外食用菌虫害防控的研究进展,并对食用菌虫害防控技术发展前景进行了展望。

Weed Control, Environmental Impact, and Net-Profit of Two-Pass Weed Management Strategies in Dicamba-Resistant Soybean (<i>Glycine max</i>) Using Conventional Tillage

Traditional two-pass weed management strategies need to be compared with new strategies in glyphosate/dicamba-resistant soybean. Weed control, soybean yield, partial profitability and environmental impact (EI) were evaluated in glyphosate/dicamba-resistant soybean using dicamba applied alone or in a tank-mix with dimethenamid-P applied preemergence (PRE). Trials were conducted at three locations during 2014 and 2015. Several PRE herbicides provided excellent control of broadleaf and grass weeds. Dicamba provided > 91% control of broadleaf weeds, and the addition of dimethenamid-P improved grass control. All weed species at the trial locations were controlled > 94% following a postemergence (POST) application of glyphosate. Weed interference reduced soybean seed yield 33% where no herbicide was applied. A single POST application of glyphosate had the lowest EI. Several treatments improved early-season weed control and reduced early-season weed density and biomass compared to glyphosate and had similar EI values. In this study, there was no benefit to yield or partial profit by including a PRE herbicide for weed management;however, the inclusion of multiple modes-of-action in a herbicide program may reduce the selection for herbicide-resistant weeds.

ENERGY ABSORPTION CONTROL CHARACTERISTICS OF AL THIN-WALLED TUBES UNDER IMPACT LOAD

An experimental investigation was carried out to study the energy absorption characteristics of thin-walled square tubes subjected to dynamic crushing by impact loading to develop the optimum structural members. Here, the controller is introduced to improve and control the absorbed energy of thin-walled square tubes in this paper. When the controller were used, the experimental results of crushing of square tubes controlled by the controller＇s elements showed a good candidate for a controllable energy absorption capability in impact crushing.

虑及控制机构运动关联的柱塞泵动态特性研究

针对柱塞泵建模过程中因函数简化控制机构及其运动关系而造成的误差大、不精准问题,提出基于控制机构运动关联的非简化建模方法。结合柱塞泵的控制原理,利用AMESim搭建功率-压力-电比例复合控制的柱塞泵仿真模型。通过对压力、电流和转速的组合控制,对柱塞泵的控制特性进行仿真测试,得到与理论研究相吻合的动态特性曲线。进一步通过台架试验对柱塞泵进行测试,试验结果表明:柱塞泵在实际工作中存在响应时间,系统流量在液压系统开启和闭合瞬间存在冲击振荡。对比两种建模思想的仿真结果,非简化模型最大相对误差分别为3.51%和5.08%,平均相对误差分别为1.74%和1.98%,均小于简化模型。柱塞泵建模准确,为实现产品性能优化和系统数字孪生提供了模型支撑。

不同调节能力水库对洪水四要素的影响分析

本文基于26个水库工程建库前后下游洪水四个要素的变化情况,分析不同调节能力水库对下游洪水的影响程度。结果表明,多年、年、季月调节水库总体对洪水首次出现时间有滞后作用、对洪水出现次数有大幅消减作用;周日调节水库对首次洪水出现时间影响不明显,且增加了下游洪水出现频次;同调节能力、不同流域的水库对下游洪水的影响程度与水库占流域面积比无明显线性关系。

售货机升降系统S型速度控制策略

在传统三闭环控制方式下,售货机升降接货系统易因启停过程中加速度突变产生冲击,导致系统运行不平稳。针对这一问题,文中对传统升降系统加减速控制策略进行改进,加入前馈和微分负反馈,提出一种S型速度曲线控制算法。根据路径规划判别条件将S型速度曲线分为七段式、六段式和四段式3种,并给出各路径约束条件下的参数求解方法和具体执行流程。将该算法运用到升降控制系统中进行仿真和实际工况测试,实验结果表明,与传统三闭环控制相比,文中所提控制策略可以提高售货机升降系统运行的平稳性,减小冲击,使速度曲线更加柔和,并能够保持较好的跟踪性能。