PD-like finite time controller with simple structure for satellite attitude control

A finite time controller with PD-like structure for satellite attitude control is proposed in this paper.The controller is constructed with simple structure based on standard PD controller.The fractional order term is designed hence system could both have strong robustness and finite time convergence rate,and the advantage of finite time control and PD control is combined in this paper.System convergence rate is discussed by Lyapunov method,and the constraint on control parameters is given by implementing the coupled term of angular velocity and attitude quaternion.Moreover,the accuracy at steady stage depending on control parameters is given hence system could converge to this field within finite time.System stability and performance is demonstrated by numerical simulation results.

Application of Simple Adaptive Control to Water Hydraulic Servo Cylinder System

Although conventional model reference adaptive control （MRAC） achieves good tracking performance for cylinder control, the controller structure is much more complicated and has less robustness to disturbance in real applications. This paper discusses the use of simple adaptive control （SAC） for positioning a water hydraulic servo cylinder system. Compared with MRAC, SAC has a simpler and lower order structure, i.e., higher feasibility. The control performance of SAC is examined and evaluated on a water hydraulic servo cylinder system. With the recent increased concerns over global environmental problems, the water hydraulic technique using pure tap water as a pressure medium has become a new drive source comparable to electric, oil hydraulic, and pneumatic drive systems. This technique is also preferred because of its high power density, high safety against fire hazards in production plants, and easy availability. However, the main problems for precise control in a water hydraulic system are steady state errors and overshoot due to its large friction torque and considerable leakage flow. MRAC has been already applied to compensate for these effects, and better control performances have been obtained. However, there have been no reports on the application of SAC for water hydraulics. To make clear the merits of SAC, the tracking control performance and robustness are discussed based on experimental results. SAC is confirmed to give better tracking performance compared with PI control, and a control precision comparable to MRAC （within 10 μm of the reference position） and higher robustness to parameter change, despite the simple controller. The research results ensure a wider application of simple adaptive control in real mechanical systems.

Identification of time-varying system and energy-based optimization of adaptive control in seismically excited structure

The combination of structural health monitoring and vibration control is of great importance to provide components of smart structures.While synthetic algorithms have been proposed,adaptive control that is compatible with changing conditions still needs to be used,and time-varying systems are required to be simultaneously estimated with the application of adaptive control.In this research,the identification of structural time-varying dynamic characteristics and optimized simple adaptive control are integrated.First,reduced variations of physical parameters are estimated online using the multiple forgetting factor recursive least squares(MFRLS)method.Then,the energy from the structural vibration is simultaneously specified to optimize the control force with the identified parameters to be operational.Optimization is also performed based on the probability density function of the energy under the seismic excitation at any time.Finally,the optimal control force is obtained by the simple adaptive control(SAC)algorithm and energy coefficient.A numerical example and benchmark structure are employed to investigate the efficiency of the proposed approach.The simulation results revealed the effectiveness of the integrated online identification and optimal adaptive control in systems.

Simple Adaptive Delta Operator Aircraft Flight Control for Accommodation of Loss of Control Effectiveness

A new proof for stability of delta operator simple adaptive control is presented in terms of a set of Linear Matrix Inequalities (LMIs). The paper shows how to design a feedforward gain to satisfy the LMIs over a polytope of loss of control effectiveness failures. The MATLAB Robust Control Toolbox is used to find the feedforward gain with the smallest norm that satisfies the LMIs. Examples are presented of the F/A-18 aircraft and the Innovative Control Effectors (ICE) tailless aircraft that show the design of a feedforward gain for a loss of control effectiveness in any one control effector. The designs use a fixed eigenstructure assignment controller for an inner loop augmented with the simple adaptive controller. Simulations of both aircraft include simultaneous loss of control effectiveness failure and lateral wind gust. Simulation results for the F/A-18 aircraft show that the adaptive controller achieves almost perfect tracking whereas the nonadaptive controller cannot achieve a coordinated turn when an aileron failure occurs. The ICE tailless aircraft uses sideslip, washed-out stability axis yaw rate, and stability axis roll rate feedback for both the inner loop eigenstructure assignment controller and the simple adaptive controller. However, the adaptive controller also uses bank angle feedback. Simulation results for the ICE tailless aircraft show that the adaptive controller achieves almost perfect tracking whereas the nonadaptive controller diverges when an all moving tip failure occurs.

Evaluation of Population Structure, Genetic Diversity and Origin of Northeast Asia Weedy Rice Based on Simple Sequence Repeat Markers

Weedy rice exerts a severe impact on rice production by competing for sunlight, water and nutrients. This study assayed the population structure, genetic diversity and origin of Northeast Asia weedy rice by using 48 simple sequence repeat markers. The results showed that weedy rice in Northeast Asia had a high genetic diversity, with Shannon＇s diversity index （I） of 0.748 and the heterozygosity （He） of 0.434. In each regional population, I value varied widely. The widest range of I （0.228-0.489） was observed in the weedy rice of Eastern China, which was larger than that of Northeast China and Korea （0.168-0.270）. The F-statistics of regional populations （Fis, Fit and Fst） also showed higher values in the weedy rice of Eastern China than those of Northeast China and Korea All weedy rice accessions were grouped into two clusters in the unweighted pair group method with arithmetic mean cluster analysis dendrogram, namely Eastern China branch and Northeastern China plus Korea branch. There was significant differentiation in genetic characteristics in weedy rice of northeastern and eastern Asia, especially in Eastern China.

西藏谷露地热田ZK401高温地热井钻井工艺技术

谷露地热田是西藏那曲—尼木地热带上的典型水热型高温地热田,安全、经济和高效的钻井工艺技术很大程度上决定了其高温地热资源的可开发利用潜力。ZK401井是在谷露地热田实施的一口优质高产探采结合井,地层以花岗岩类为主,其岩石硬度大,机械钻速低,钻头使用寿命短。自上而下揭露多层热储,其35~41m即可揭露124.8℃中温地热流体,汽水总量约40 t·h^(-1);50~320 m揭露超过120℃的中温热储,汽水总量约30~35 t·h^(-1);320~1320 m揭露186.9℃高温热储,汽水总量高达348 t·h^(-1),具有热储埋深浅、温度高,断裂构造发育,地层出水量大的特点,高温及水侵作用致使钻井液极易失效,井喷风险大,安全钻井难。为解决上述钻井施工难点,进行了高温地热钻井关键技术研究。通过采用异形齿PDC钻头和岩石热裂提速技术,使单只异形齿PDC钻头进尺较同规格牙轮钻头提高了23%~48%,使三开井段花岗岩类地层的平均机械钻速提升至3.18 m·h^(-1)。通过优化井身结构,采用简易控压钻井技术,利用低温清水作为二开及三开钻进循环钻井液,达到了及时发现并有效保护热储层和控制井喷风险的目的;实现了ZK401井在520 m揭露186.9℃高温热储且汽水总量达348 t·h^(-1)苛刻条件下的安全、持续钻进,且非生产时间较采用常规钻井技术的邻井缩短了37%,极大地降低了钻井成本,提高了高温地热资源的可开发利用潜力。为后续该区域乃至其他地区解决高温地热井钻井施工提供参考。

土壤重金属污染阻控技术研究进展

阐述了土壤重金属的赋存特征,归纳了土壤原位控制技术和原位阻隔技术的近期研究成果,探讨了不同治理手段对于土壤重金属污染的控制效果和存在的不足点。土壤重金属污染是我国环境治理的一大难题,如彻底地治理土壤重金属污染存在工程量大、消耗成本高、难以规模化推广等问题。土壤重金属阻控技术通过降低重金属释放风险以达到土壤治理的目的,具有处理成本低廉、操作简单等特点,是一项更为先进的治理理念。就该领域的研究方向提出几点建议与展望,旨在能够推动我国土壤重金属治理技术的进步与革新。

中医药治疗老年单纯收缩期高血压的临床研究结局指标分析

[目的]梳理中医药治疗老年单纯收缩期高血压(ISH)的随机对照试验(RCT)的评价指标,构建中医药治疗老年ISH临床试验核心指标集。[方法]检索PubMed、CoChrane library、Embase、中国知网数据库、万方数据库、维普数据库中应用中药联合长效钙拮抗剂(CCB)或肾素-血管紧张素-醛固酮系统阻断剂(ACEI或ARB)干预老年ISH的随机对照临床研究,检索时限均为建库至2019年12月31日。[结果]纳入38篇RCT,共计2848例患者,涉及396个指标,频次排列前16位的指标依次为:诊室收缩压(7.04%)、降压有效率(6.31%)、中医证候疗效(6.31%)、诊室舒张压(5.56%)、肝功能(4.29%)、肾功能(4.29%)、血常规(4.04%)、尿常规(3.79%)、不良反应发生率(3.54%)、夜间平均收缩压(3.28%)、24小时平均收缩压(3.03%)、日间平均收缩压(3.03%)、中医证候积分(3.03%)、诊室脉压差(2.78%)、日间平均舒张压(2.78%)及夜间平均舒张压(2.78%)。[结论]中医药治疗老年ISH的指标选择存在较多的问题,如差异性较大、指标测量时点差异大、缺乏中医药特色等,需加快研制老年ISH;核心指标集。

行政激活自治:农村人居环境治理有效的实践逻辑

作为满足农民美好生活需要的组成部分,农村人居环境治理实践正在各地展开。调研发现,囿于“服务者角色”对“规制职能”的替代、“技术性治理”对“地方知识”的拒斥、“控制权下沉”对“政策转化”的限制,农村人居环境治理中的行政支配造成“自治”及其背后的农民主体处于“被围困”状态。为此,应创设村庄自治机制和支持结构、实现行政服务和规制职能统合,塑造知识民主观念和沟通机制、完成行政技术与地方知识适配,厘清乡村关系和做好政策转换、保证行政治权与自主治理有效等,以达成农村人居环境治理有效、有力和可持续。

垂发冷弹射导弹四推冲器转弯动力学研究

针对四推冲器转弯控制技术与其他垂发冷弹射导弹转弯控制技术存在较大差异的问题,建立了导弹的转弯段线运动方程、姿态运动方程和待转信息方程;设计了转弯时序,通过引入预估模型及相应判据设计了转弯控制策略;并基于上述策略开展了参数匹配研究;通过简易装置实现了弹体轴线的大范围调节。通过仿真算例验证了所提出参数匹配关系以及转弯控制策略的有效性。

电务卡控模式下车站CTC数据文件一键换装系统的实现

针对铁路运营线路调度集中(CTC,Centralized Traffic Control)系统改造时,数据文件换装效率低、可能出现天窗点外作业的问题,设计了电务安全卡控模式下车站CTC数据文件一键换装系统,运用gSOAP(Genivia Simple Object Access Protocol)、多线程技术、双机文件服务器的存储方法、CRC32算法对数据文件进行校验等关键技术,实现了电务安全卡控模式下CTC数据文件的一键换装功能。该系统已在多个铁路局集团公司推广应用,在电务安全卡控模式下使用该系统进行车站CTC数据文件同步换装作业,从源头上确保了换装作业过程的安全,进一步提高了换装作业的质量和效率,取得了良好的应用效果。

单线小曲线切翼缘简支箱梁施工技术研究

主要研究了在高铁车站出站口变线处及其他特殊周边环境下曲线半径过小导致梁缝的宽度过大不能保证线路的平顺性,以及由于桥梁景观的要求而进行的箱梁特殊设计及施工的问题。分析了在曲线半径过小的情况下,桥梁设计中的处理原则和方法,以及在预制过程中模板设计的要点、支座板的位置、接地端地的位置、接触网及下锚拉线的位置、桥面无砟轨道预埋套筒的位置、钢筋尺寸、张拉力的变化等质量控制要点。

A Multi-Interface Remote Monitoring and Control System Architecture Based on Embedded Server

This paper presents a multi-interface embedded server architecture for remote real-time monitoring system and distributed monitoring applications. In the scheme,an embedded microprocessor( LPC3250 from NXP) is chosen as the CPU of the embedded server with a linux operation system( OS) environment. The embedded server provides multiple interfaces for supporting various application scenarios. The whole network is based on local area network and adopts the Browser / Server( B / S) model. The monitoring and control node is as a browser endpoint and the remote node with an embedded server is as a server endpoint. Users can easily acquire various sensors information through writing Internet protocol address of remote node on the computer browser. Compared with client / server( C / S) mode,B / S model needs less maintain and can be applicable to large user group. In addition,a simple network management protocol( SNMP) is used for management of devices in Internet protocol( IP) networks. The results of the demonstration experiment show that the proposed system gives good support to manage the network from different user terminals and allows the users to better interact with the ambient environment.

Control of seismic and operational vibrations of rotating machines using semi-active mounts

A dual isolation problem for rotating machines consists of isolation of housing structures from the machine vibrations and protection of machines during an earthquake to maintain their functionality. Desirable characteristics of machine mounts for the above two purposes can differ significantly due to difference in nature of the excitation and performance criteria in the two situations. In this paper, relevant response quantities are identified that may be used to quantify performance and simplified models of rotating machines are presented using which these relevant response quantities may be calculated. Using random vibration approach with a stationary excitation, it is shown that significant improvement in seismic performance is achievable by proper mount design. Results of shaking table experiments performed with a realistic setup using a centrifugal pump are presented. It is concluded that a solution to this dual isolation problem lies in a semi-active mount capable switching its properties from ‘operation-optimum’ to ‘seismic-optimum’ at the onset of a seismic event.

NONLINEAR STABLE ADAPTIVE CONTROL BASED UPON ELMAN NETWORKS

Elman networks' dynamical modeling capability is discussed in this paper firstly.According to Elman networks' unique structure,a weight training algorithm is designed and a nonlinear adaptive controller is constructed.Without the PE presumption,neural networks controller's closed loop properties are studied and the whole Elman networks' passivity is demonstrated.

电机变频调速器电压稳态PLC控制仿真

为了提高因较多简谐波注入变频调速设备,而导致的电压波动等问题,提出电机变频调速器电压稳态PLC控制方法。首先对含有基波与一对简谐波分量的电压波形进行研究,通过对正、负包络波形的分析,得出含有一个简谐波与一对简谐波电压变化的波形具有相似性。然后对含有一对间谐波的电压峰值波动率和简谐波电压进行分析与研究,得出电压峰值波动率与简谐波的频率没有关系,高频简谐波对电压的峰值波动影响要比低频简谐波强。最后将同步电机定子和转子的电气方程和运动方程引入到控制器中,通过PLC控制技术对电机的调速进行控制,为了使变频器能够对系统侧的功率变化作出相应的响应,采用控制策略对整流侧控制器进行控制,以维持直流侧的电压向逆变器侧输送稳定的功率。实验结果表明,采用上述方法对变频调速装置的电压进行控制,电压质量能够提升61.3%,电压波形畸变能够降低5.3%,并且电机的动态响应性能和稳态性能均较好,大大提高了同步的精度。

控释肥一次性侧深施对水稻生长、氮素利用和产量的影响

为探索机插水稻一次性侧深基施的轻简高效栽培技术,以水稻品种“全两优鄂丰丝苗”为材料,设置不施肥(N0)、控释肥一次性侧深基施(N1)、控释肥减氮10%一次性侧深基施(N2)、控释肥减氮20%一次性侧深基施(N3)和传统施肥(CK)处理,测定水稻分蘖动态、主要生育期的叶面积指数与干物质积累量、齐穗期根系指标、氮素利用效率与产量,研究控释肥一次性侧深施对水稻生长、氮素吸收利用和产量的影响。结果显示:与CK相比,处理N1、N2显著增产12.99%~14.85%和5.47%~6.09%,处理N3产量与CK差异不显著,对施肥量和产量拟合后分析,在减氮18.72%时与CK产量持平。与CK相比,控释肥一次性侧深施处理显著提高了水稻的成穗率、提高了生育中后期的叶面积指数和干物质积累量、促进了根系的生长并扩大了根系的分布范围,处理N1、N2和N3与处理CK相比,分别提高氮素表观利用率1.21%~46.57%、氮素农学利用率18.85%~61.73%、氮素生理利用率8.90%~17.71%和偏生产力12.99%~23.61%。研究结果表明,控释肥一次性侧深施促进了根系生长,增加水稻有效穗数,提高了氮素利用效率且大幅较少施肥次数,在减氮18.72%的范围内,可实现水稻的高产、稳产。

A Backstepping Simple Adaptive Control Application to Flexible Space Structures

Although the simple adaptive control （SAC） is widely studied both in theory and application in flexible space structure control and other control problems, it is restricted by the almost strictly positive real （ASPR） conditions. In most practical control problems, the ASPR conditions are not satisfied. Therefore, based on the SAC theory, this paper proposes a backstepping simple adaptive control algorithm which suits the system with arbitrary relative degree with no need of parallel feed forward compensa- tor. The proposed control algorithm consists of decomposition of the arbitrary relative degree system into a known subsystem and an unknown ASPR subsystem which are connected in cascade, design of constant output feedback controller for the known subsystem, and implementation of backstepping method and SAC of the unknown ASPR subsystem. Inheriting the characteristics of the SAC, this method can be adaptive online for the parameter uncertainties. Then, the application of the proposed controller to large flexible space structure with collocated sensors and actuators is studied, and the simulation results validate the proposed controller. It is a new strategy to apply the classical SAC to high relative degree plants.

针刺治疗单纯性近视疗效的Meta分析

目的:评估针刺治疗单纯性近视的疗效与安全性。方法:计算机检索中国知网,万方数据库,维普数据库,中国生物医学文献数据库,Web of Science,PubMed,Cochrane library等数据库库公开发表的关于针刺治疗近视的随机对照试验研究,时间截止到2021年2月1日。根据文献纳入与排除标准筛选相关文献,按照Cochrane 5.3系统评价手册对文献进行质量评价,RevMan 5.3软件对其结局指标进行Meta分析。结果:共纳入临床随机对照试验10篇,涉及患者1240例。Meta结果分析显示,与对照组相比,针刺治疗单纯性近视的有效率更高[OR=3.93,95%CI(3.0~5.14),P<0.001];在提高患者视力[MD=0.15,95%CI(0.08~0.22),P<0.001]、减慢眼轴增长速度[MD=-0.13,95%CI(-0.21~-0.04),P=0.002]、提高调节灵敏度[MD=3.51,95%CI(2.65~4.37),P<0.0001]等指标方面,均显示针刺治疗单纯性近视具有显著作用。纳入文献中有3篇提及不良反应的发生和处理,其余7篇均未描述。结论:文献证据表明,在常规治疗的基础上加用针刺治疗可有效提高视力,改善调节灵敏度,减慢眼轴增长速度。本研究分析未发现严重不良反应,但仍需要更多高质量文献佐证此分析。