Determining heating pipe temperature in greenhouse using proportional integral plus feedforward control and radial basic function neural-networks

INTRODUCTION The objective of greenhouse environment controlis to create an ideal climatic condition for plant growth.The interior air temperature is the most importantcontrol factor. Generally, heating facilities must beinstalled in the greenhouse in order to make the inte-rior air meet the need of the crop in cold days. Hotwater heating is the prevailing method. In order tosave energy, precise temperature control is necessary(Chalabi et al., 1996). For precise control of interior…     

Proportional integral plus multi-frequency resonant current controller for grid-connected voltage source converter under imbalanced and distorted supply voltage conditions

This paper proposes a current control scheme for a grid-connected pulse width modulator （PWM） voltage source converter （GC-VSC） under imbalanced and distorted supply voltage conditions. The control scheme is implemented in the positive synchronously rotating reference frame and composed of a single proportional integral （PI） regulator and multi-frequency resonant controllers tuned at the frequencies of 2ω and 6ω, respectively. The experimental results, with the target of eliminating the active power oscillations and current harmonics on a prototype GC-VSC system, validate the feasibility of the proposed current control scheme during supply voltage imbalance and distortion.     

运动训练对大鼠骨骼肌PI3K、PTEN和AKT基因表达的影响

目的:探讨中等强度耐力训练对骨骼肌PI3K,PTEN和Akt基因和蛋白表达的影响。方法:12只雄性SD大鼠随机分为安静组和运动训练组,每组6只。训练组采用Bedford训练方案。训练8周后两组大鼠安静状态下处死,取比目鱼肌和腓肠肌。采用Real-time PCR和Western Blotting等方法测定大鼠比目鱼肌和腓肠肌PI3K、PTEN和Akt基因的mRNA和蛋白表达。结果:8周的训练,腓肠肌PI3K、PTEN和Akt mRNA水平显著降低,而PI3K和Akt的蛋白相对表达量显著增强,PTEN蛋白相对表达量下降;比目鱼肌Akt mRNA下降,PI3K和PTEN mRNA无显著改变,PTEN和Akt1蛋白相对表达量下降,PI3K蛋白表达增强。结论:PI3K、PTEN和Akt基因表达可受耐力训练的诱导,该诱导可能发生于转录水平或翻译水平,在同一组织中mRNA与蛋白质表达的关系较复杂,协同性较低,耐力训练中PI3K、PTEN和Akt基因的转录和翻译可能相对独立,并有肌纤维类型的特异性。     

IGF1–PI3K-induced physiological cardiac hypertrophy: Implications for new heart failure therapies,biomarkers, and predicting cardiotoxicity

Heart failure represents the end point of a variety of cardiovascular diseases. It is a growing health burden and a leading cause of death worldwide. To date, limited treatment options exist for the treatment of heart failure, but exercise has been well-established as one of the few safe and effective interventions, leading to improved outcomes in patients. However, a lack of patient adherence remains a significant barrier in the implementation of exercise-based therapy for the treatment of heart failure. The insulin-like growth factor 1 (IGF1)–phosphoinositide 3-kinase (PI3K) pathway has been recognized as perhaps the most critical pathway for mediating exercised-induced heart growth and protection. Here, we discuss how modulating activity of the IGF1–PI3K pathway may be a valuable approach for the development of therapies that mimic the protective effects of exercise on the heart. We outline some of the promising approaches being investigated that utilize PI3K-based therapy for the treatment of heart failure. We discuss the implications for cardiac pathology and cardiotoxicity that arise in a setting of reduced PI3K activity. Finally, we discuss the use of animal models of cardiac health and disease, and genetic mice with increased or decreased cardiac PI3K activity for the discovery of novel drug targets and biomarkers of cardiovascular disease.     

电机实验中稳恒负载的实现

在电机实验中,转矩和转速的测试是非常关键的.转矩和转速的测试与负载有直接关系.在大多数电机实验中,负载是利用直流发电机接电阻或者是利用交流异步电机的能耗制动来实现的,也有使用电磁涡流制动器来实现的,这3种负载的转矩都是随转速变化的,这使转矩和转速的测试很不方便.针对这种情况,文章采用磁粉制动器作为负载,实验中发现磁粉制动器的转矩随着转速变化也有变化.为此,该文在磁粉制动器的励磁回路中设计了一闭环调节器,实现了稳恒负载.这给电机实验带来了很大的方便.     

微机控制的磁流体发电机输出电路的探究

采用PIC16C74单片机为控制系统的核心,简化了控制电路,采用全桥式逆变电路,实现实验电路模型的设计。通过对部分功率转换器件的电流、电压的波形分析和仿真,证明电路设计可行,软件运行,利于调试,并提供了磁流体发电机实际应用时的部分参数模型。     

电冰箱单片机控制系统的设计

介绍了一种用单片机开发的智能电冰箱控制系统。该系统以AT89C5 1单片机为核心 ,分为温度采集电路、除霜电路、键盘电路、显示电路、制冷压缩机和除霜电热丝启停控制电路等模块并对系统的工作原理作了详细说明     

UPFC的神经网络PI控制方法研究

为了满足工程上广泛应用的PI控制器的性能要求，又能克服一般PI控制器参数整定和调整的困难，基于dqo同步旋转坐标系下的UPFC串联侧的数学模型。采用BP神经网络PI控制器分别对有功和无功进行控制，使PI控制器的参数可以自动整定，省去了繁琐的人工整定过程，并能随系统的变化在线调节，使有功和无功达到较好的控制性能。     

高等职业教育呼唤PI形象设计

高职院校创立PI形象工程是时代和社会发展对高职院校提出的要求。本旨在通过PI的必要性、构成、特点及功能的阐述，来说明PI形象设计对挖掘高职院校的精神、办学理念，提高校园化格调，塑造学校良好形象的重要作用和时代意义。     

高压直流输电系统智能控制器的设计

高压直流输电作为一种新兴发展输电方式,具有线路输电能力强、低损耗、双侧交流系统不需同步运行、发生故障时对电网造成的低损耗等优点,高压直流输电系统控制器是输电系统正常运行的有力保证,能够满足我国的输电要求。针对换流器整流部分使用PI控制器,构建高压直流输电系统模型,并通过MATLAB仿真确定基于PI控制器的高压直流输电系统智能控制器。