共查询到20条相似文献,搜索用时 234 毫秒
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对粮食或食品进行烘干处理有利于运输、储存与后续加工,而在干燥过程中对温度的控制非常重要。为对比不同算法在温度控制方面的差异,使用西门子S7-200 SMART可编程逻辑控制器(Programmable logic controller,PLC)进行程序设计,并采用昆仑通态触摸屏实现人机交互。同时,为达到提高温度控制精度的目的,通过对传统比例-积分-微分(Proportion-integral-derivative,PID)控制算法与模糊控制算法进行改进,设计了模糊PID复合控制算法和模糊PID切换控制算法。采用梯形图语言对上述4种控制算法进行编程,并进行PLC控制烘干箱的试验验证。结果表明,新设计的模糊PID复合控制算法和模糊PID切换控制算法均在一定程度上反映了其结合要素各自的优点,能有效克服传统PID控制算法动态特性差和模糊控制算法稳态特性差的缺点。当温度由30 ℃升至设定温度72 ℃时,与模糊PID切换控制算法相比,模糊PID复合控制算法能将调节时间缩短6 s,且稳态误差减小0.1 ℃。 相似文献
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以无线传感器网络在蔬菜温室环境监控中的应用为目的,研究几种常用自组网路由算法原理。通过对ABR、TORA、DSR、DSDV、AODV等不同路由算法的分类归纳和各自优缺点对比,得出AODV算法因在降低开销的同时还能减小通信延时而最适用于无线传感器网络的结论,因此以实际应用为目的对AODV算法的工作原理进行研究和梳理。使用NS2和NAM网络仿真工具对使用AODV算法的无线传感器网络进行模拟场景仿真,使用gwark和gnuplot工具对仿真数据进行分析,重点研究一定区域面积下节点数量增加时网络传输延时和丢包率的变化,得出应用场景确定时节点数量对通信质量的影响关系,为今后WSN在蔬菜温室中的实际应用提供理论依据。 相似文献
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花卉保护地生产有许多方式,我们重点介绍温室盆栽花卉的管理方法。 1.温室环境的调控:在温室中,植物所需的环境条件几乎都可人为调节,主要的有温度、湿度、光照和空气等。不同种类的花卉以及不同的生长发育时期对温度的要求均不同,因此要通过加温、通风和遮 相似文献
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无线传感器网络中一种改进的DV-Hop定位算法 总被引:2,自引:0,他引:2
针对DV-Hop算法在无线传感器网络节点分布不均匀时定位误差比较大的问题,提出了一种针对DV-Hop的改进定位算法。该改进算法主要是利用RSSI测量技术增加锚节点;在给定约束下引入“可能存在区域”这一概念,并以该可能存在区域的面积作为目标函数,对未知节点的位置利用非线性共轭梯度法进行逼近,从而使节点定位误差达到最小。通过仿真验证了节点通信半径和锚节点比例对定位误差的影响,结果表明,该改进算法将节点定位精度提高了5%~10%。 相似文献
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无糖组培技术的应用及发展前景 总被引:5,自引:0,他引:5
无糖组培技术即光独立培养技术(PhotoautotrophicMicropropagation)。该技术由国家外专局和昆明市科技局1997年从日本千叶大学引进。其特点在于将大田温室环境控制的原理引入到常规组织培养应用中,用CO2气体代替培养基中的糖作为组培植株的碳源,采用人工环境控制的手段,提供适宜不同种类组培植株生长的光、温、水、气、营养等条件,促进植株的光合作用,从而促进植物的生长发育,达到快速繁殖优质种苗的目的。1常规组培技术与无糖组培技术的比较1.1培养容器培养容器是小植株生长的场所,它直接影响小植物的生长发育。在传统的组织培养微繁殖中… 相似文献
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针对模糊控制系统中切换时延较长和切换次数较多的问题,研究了一种基于模糊控制系统的垂直切换判决算法。在基于信号强度判决时将RSS作为门限值,提高系统判决能力;同时,将网络参数和服务类型作为判决因素,结合层次分析法引入并行的模糊控制系统,缩短了切换判决的时间、选择适合用户的最佳网络,做出垂直切换。仿真结果表明,该算法减少了切换次数,降低了切换时延,增强了系统的性能。与传统的切换算法相比较,该算法对切换的判决因素考虑的更全面,兼顾了用户终端的使用环境及成本问题,有效地保证了网络的服务质量。 相似文献
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Fuzzy PID controller was applied in variable air volume system. The task was to control the temperature of supply air and the temperature of air conditioned room (the return air temperature) close to their respective targets. The fuzzy PID control system of supply air temperature and return air temperature was designed respectively. The supply air temperature was controlled through adjusting the valve opening of chilled water. And the indoor temperature was controlled through adjusting the rotational speed of variable frequency ventilator. The supply air temperature and the indoor temperature (return air temperature) were controlled online by fuzzy PID controller. Thus, it was shown that the design of fuzzy PID controller was reasonable and the effect of fuzzy PID control was well. 相似文献
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The construction and function of high temperature melt viscosity test instrument are introduced in this paper. And the character of temperature control system is given. In order to improve dynamic and static performance of the temperature control system, a new method is proposed which combines threshold control with adaptive fuzzy PID control. While the current temperature of the heating furnace is much lower than the given temperature, threshold control works in order to protect system and improve dynamic performance. When the current temperature is close to the given value, adaptive fuzzy PID control works to improve static performance. At last, simulation and experiment results validate the proposed control method. 相似文献
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依据温室控制要求,介绍了模糊控制技术在温室控制系统中的应用,给出了模糊控制器的实现过程。实践表明,该控制器具有良好的控制效果。 相似文献
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Fuzzy controller can achieve satisfactory dynamic performance even for complicated process without mathematical model of the process.Its main imperfection is the existence of steady state error and ultimate oscillatory in the process output. This limits its application area. How to eliminate the steady state error while keep its good dynamic performance has been paid much attention. The strategy to introduce integral function to the conventional fuzzy control system is put forward in this paper to overcome the above problem. After expound two key factors on introducing integral action,an intelligent integral algorithm has been employed,and two methods on introduction of the intelligent integral to the fuzzy control system are proposed. Their characteristics and applied situations are summarized. 相似文献
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This paper presents the character of cascade control system and the design of the main loop and subloop. A cascade PID control system based on MATLAB is designed, which is controlled by MATLAB control program based on incremental PID control algorithm and PID parameter tuning method based on computer control. The results show that the control system has good performance. 相似文献
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The mathematic models and basic theory of constant modulus algorithm (CMA) for blind channel equalization are introduced. An improved algorithm with variable step size is proposed based on CMA. The improved algorithm uses the mean square error (MSE) to obtain the new variable step size to solve the contradiction between the convergence rate and accuracy in traditional CMA with fixed step. To smooth the MSE learning curve for easy comparison, an ensemble average technique is used to analyze the performance of convergence with different step sizes. The theoretical analysis and the simulation results show that the improved algorithm is superior to the traditional constant modulus(CM) in terms of convergence speed and residual error. 相似文献