具有反向PWM的阀门定位器控制方法及实现

压电式阀门定位器在行程范围内动态特性是非线性的,传统5步开关法在控制阀门过程中存在超调和PWM控制脉冲个数偏多的缺点。研究提出带反向PWM降速功能的五步开关法,在闭环控制过程中根据执行器运行速度的大小进行正向PWM控制和反向PWM控制的切换;在参数自整定过程中,针对不同位置寻找相应的最佳正向PWM占空比,并实现任意位置最佳正向PWM占空比的实时计算。研制了基于MSP430F5418A低功耗单片机的硬件和软件系统,实时实现参数自整定和控制算法。针对不同的气动调节阀进行了实验,取得较好的控制效果。

智能阀门定位器阀位自适应控制算法研究

智能阀门定位器是智能电气调节阀的控制核心,其中的阀位控制算法是实现调节阀阀杆位置精确定位和阀门开度精确调节的关键。传统的五接点开关算法具有算法简单、响应速度快的特点,但是存在参数调整困难,无法适应不同阀芯、不同行程调节阀精确定位的控制要求。为此将传统五节点开关控制与PID控制算法相结合,研究实现了一种阀位自适应控制算法。通过系统初始化程序实现了控制参数的初始整定并在阀位控制过程中实现了PID控制参数的自适应微调。阀门定位控制试验结果表明:该阀位自适应控制算法实现了阀位的准确控制,阀位定位精度满足±1%FS的设计要求。

调节阀在忠县天然气净化厂的应用探析

在天然气净化装置的生产过程中,调节阀具有重要的作用。它直接控制工艺介质,接受DCS发出的控制信号,改变调节参数,把被调参数控制在所要求的范围内,从而实现天然气净化装置的生产过程自动化。本文主要介绍忠县天然气净化厂自投产以来调节阀所出现的主要问题,通过分析故障原因并提出相应的改进措施,以提高调节阀运行的可靠性,从而确保天然气净化装置的平稳运行。

智能电—气阀门定位器

气动调节阀是工业过程控制中一种重要的执行器。阀门定位器作为其主要附件 ,能够显著改善阀门的特性 ,提高控制的精度、速度和灵活性。本文论述了气动调节阀及定位器的作用和基本原理 ,并论述了智能电 -气阀门定位器的控制电路结构及五接点开关控制策略。相对于传统定位器 ,具有控制精度高、适应性强、调校方便、控制灵活等特点。

海岸湿地针叶林-阔叶林突变临界维持机制研究

There is an abrupt boundary between two well-developed wetland forests, a stand consisting of a broad-leaved, nitrogen-fixer Alnusjaponica and a stand of the needle-leaved Picea glehnii Masters, in eastern Hokkaido, Japan. To clarify maintenance mechanisms, we studied the forest profile, water level, groundwater and precipitation chemistry, seedling establishment patterns in relation to microhabitats, and seed migration. The profile of groundwater level insufficiently explained the abrupt boundary formation, while the groundwater chemistry differed significantly between the two forests ; i.e., EC, Na^＋, K^＋, Mg^2＋, Ca^2＋ and Cl^- were higher in P. glehnii forest and pH was lower. Precipitation in P. glehnii forest contained richer Na＋, Ca^2＋ and Cl^-, indicating that the differences in surface-water chemistry were mostly derived from precipitation. Solar radiation was less than 2.2 MJ.m^-2.d^-1 on P. glehnii forest in late June, while that was patchily distributed in A.japonica forest with a range from 1.0 to 3.7 MJ＇m^-2＇d^-1. Moss cover on the soil surface, most of which were made of Sphagnum spp., was 60% in P. glehnii forest, but was 10% in A. japonica forest. Surface water chemistry represented by pH was considered to determine the development of Sphagnum moss. About 70% of P. glehnii seedlings 〈 1.3 m in height established on moss cover. Seed-sowing experiments suggested that seed germination and seedling survival for both species were significantly higher in P. glehnii forest. Therefore, the regeneration of P. glehnii in A. japonica forest was negligible, owing to the paucity of favorable microhabitats and low seedling establishment. A. japonica regenerated only by resprouting, and the seedlings were few in both forests. In addition, A. japonica seed migration into the P. glehnii forests was greatly restricted, and low solar radiation in the P. glehnii forest contributed to low seedling survival. Based on those results, we concluded that Picea glehnii and Alnusjaponica could develop distinct and selfish environments being unsuitable for the other species and inhibit natural afforestation of another species each other by excluding invasion.

Maintenance of an abrupt boundary between needle-leaved and broad-leaved forests in a wetland near coast

There is an abrupt boundary between two well-developed wetland forests, a stand consisting of a broad-leaved, nitrogen-fixer Alnus japonica and a stand of the needle-leaved Picea glehnii Masters, in eastern Hokkaido, Japan.To clarify maintenance mechanisms, we studied the forest profile, water level, groundwater and precipitation chemistry, seedling establishment patterns in relation to microhabitats, and seed migration.The profile of groundwater level insufficiently explained the abrupt boundary formation, while the groundwater che-mistry differed significantly between the two forests;i.e., EC, Na+, K+, Mg2+, Ca2+ and Cl-were higher in P.glehnii forest and pH was lower.Precipitation in P.glehnii forest contained richer Na+, Ca2+ and Cl-, indicating that the differences in surface-water chemistry were mostly derived from precipitation.Solar radiation was less than 2.2 MJ·m-2·d-1 on P.glehnii forest in late June, while that was patchily distributed in A.japonica forest with a range from 1.0 to 3.7 MJ·m-2·d-1.Moss cover on the soil surface, most of which were made of Sphagnum spp., was 60% in P.glehnii forest, but was 10% in A.japonica forest.Surface water chemistry represented by pH was considered to determine the development of Sphagnum moss.About 70% of P.glehnii seedlings < 1.3 m in height established on moss cover.Seed-sowing experiments suggested that seed germination and seedling survival for both species were significantly higher in P.glehnii forest.Therefore, the regeneration of P.glehnii in A.japonica forest was negligible, owing to the paucity of favorable microhabitats and low seedling establishment.A.japonica regenerated only by resprouting, and the seedlings were few in both forests.In addition, A.japonica seed migration into the P.glehnii forests was greatly restricted, and low solar radiation in the P.glehnii forest contributed to low seedling survival.Based on those results, we concluded that Picea glehnii and Alnus japonica could develop distinct and selfish environments being unsuitable for the other species and inhibit natural afforestation of another species each other by excluding invasion.

一种智能阀门定位器控制算法

针对调节阀工作中控制速度不平滑、容易控制超调等问题,在智能阀门定位器控制算法设计中,采用脉冲调宽控制的方式,基于"五步开关"算法,提出了对定位速度量化控制的算法,实现了算法间的无扰切换。实验结果表明:该算法有效解决了上述问题,并具有一定的自适应及鲁棒特性。

浅谈电磁感应技术在隔爆型智能阀门定位器中的应用

以HVP30隔爆型智能阀门定位器为研究对象,阐述了电气设备主要的防爆技术种类,针对隔爆型智能阀门定位器的工作原理及电磁感应技术及阀门定位器的控制应用进行了介绍。

Experiment on Leader Propagation Characteristics of Air Gaps in UHVDC Transmission Towers Under Positive Switching Impulse Voltages

Rapid developments in EHV/UHV transmission systems require a deeper understanding of the mechanism of long air gap discharge.Leader propagation is one of the main processes in long gap breakdown.In this paper,the leader propagation characteristics of real size±800 kV UHVDC transmission tower gaps under positive switching impulse voltages(185/2290μs)are investigated.An integrated observation platform consisting of an impulse voltage divider,a coaxial shunt,a high-speed video camera,and a set of integrated optical electric field sensors(IOES),is established.The waveforms of impulse voltage,discharge current,electric field variation at specific positions,and time-resolved photographs of discharge morphology are recorded.Axial leader velocity and the relationship between leader advancements and injected charge are obtained.The typical value of leader stable propagation velocity is 1.7–2.2 cm/μs,which varies slightly with the gap length and applied voltage amplitude.The leader velocity in the re-illumination process is much higher,and is seen as varying from 5 cm/μs to 30 cm/μs,with an average value around 10 cm/μs.The charge in leader channel per unit length is 20–40μC/m,which illustrates a near-direct proportion relationship between discharge current and leader velocity.The observed parameters are important for further simulation of the tower gap breakdown processes.

Regional Stability of Positive Switched Linear Systems with Multi-equilibrium Points

This paper studies the regional stability for positive switched linear systems with multi-equilibrium points （PSLS-MEP）. First, a sufficient condition is presented for the regional stability of PSLS-MEP via a common linear Lyapunov function. Second, by establishing multiple Lyapunov functions, a dwell time based condition is proposed for the regional stability analysis. Third, a suprasphere which contains all equilibrium points is constructed as a stability region of the considered PSLS-MEP, which is less conservative than existing results. Finally, the study of an illustrative example shows that the obtained results are effective in the regional stability analysis of PSLS-MEP.

An UPLC-MS/MS method for simultaneous determination of multiple constituents in Guizhi Fuling capsule with ultrafast positive/negative ionization switching

Guizhi Fuling capsule(GFC), a traditional Chinese medicine(TCM) with effects of promoting blood circulation and dissipating blood stasis, has been widely used in the clinic. Because of the complex matrix and various chemical structure types, quality control of GFC remains great challenge. In the present study, an ultra performance liquid chromatography hybrid triple-quadrupole mass spectrometry(UPLC-QQQ MS) method with ultrafast positive/negative ionization switching was developed for simultaneous determination of 18 bioactive components in GFC, including methyl gallate, ethyl gallate, oxypaeoniflorin, benzoic acid, albiflorin, paeonolide, paeoniflorin, 1, 2, 3, 4, 6-pentagalloylglucose, mudanpioside C, benzoyloxypaeoniflorin, benzoylpaeoniflorin, pachymic acid, amygdalin, cinnamaldehyde, paeonol, cinnamic acid, 4-hydroxybenzoic acid, and gallic acid. Separation was performed on an Agilent Zorbax Extend–C18 column(2.1 mm × 50 mm, 1.8 μm), using a gradient elution with acetonitrile and water containing 0.1% formic acid. Cholic acid was selected as the internal standard. This newly developed method was fully validated for linearity, precision, accuracy, and stability, and then applied to quality assessment of GFC. Finally, the batch-to-batch reproducibility of GFC samples was evaluated by the cosine ration and Euclidean distance method, which showed high quality consistency. The results demonstrated that the developed method provided a reasonable and powerful manner for quality control of GFC.

Stability of Switched Positive Descriptor Systems with Average Dwell Time Switching

In this paper, the problems of stability for a class of switched positive descriptor systems(SPDSs)with average dwell time(ADT) switching are investigated. First, based on the equivalent switched system and the properties of the projector matrix, sufficient stabilities are given for the underlying systems in both continuoustime and discrete-time contexts. Then, a sufficient stability condition for the SPDS with both stable and unstable subsystems is obtained. The stability results for the SPDSs are represented in terms of a set of linear programmings(LPs) by the multiple linear co-positive Lyapunov function(MLCLF) approach. Finally, three numerical examples are given to illustrate the effectiveness of the obtained theoretical results.

Event-Triggered L1-Gain Control of Nonlinear Positive Switched Systems

This paper is concerned with the event-triggered L1-gain control of a class of nonlinear positive switched systems.First,an event-triggering condition in the form of 1-norm is presented for the systems.By virtue of the event-triggering strategy,the original system is transformed into an interval uncertain system.An event-triggered L1-gain controller is designed by decomposing the controller gain matrix into the sum of nonnegative and non-positive components.Under the design controller,the resulting closed-loop systems are positive and L1-gain stable.The obtained approach is developed for the systems subject to input saturation.All presented conditions are solvable in terms of linear programming.Finally,two examples are provided to verify the effectiveness of the design.

Event-triggered Control of Positive Switched Systems with Actuator Saturation and Time-delay

This paper investigates the event-triggered control of positive switched systems with randomly occurring actuator saturation and time-delay,where the actuator saturation and time-delay obey different Bernoulli distributions.First,an event-triggering con-dition is constructed based on a 1-norm inequality.Under the presented event-triggering scheme,an interval estimation method is utilized to deal with the error term of the systems.Using a co-positive Lyapunov functional,the event-triggered controller and the cone attraction domain gain matrices are designed via matrix decomposition techniques.The positivity and stability of the resulting closed-loop systems are reached by guaranteeing the positivity of the lower bound of the systems and the stability of the upper bound of the systems,respectively.The proposed approach is developed for interval and polytopic uncertain systems,respectively.Finally,two examples are provided to illustrate the effectiveness of the theoretical findings.