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排序方式: 共有691条查询结果,搜索用时 15 毫秒
1.
随着电气控制技术的发展和计算机技术的广泛应用,单片机逐渐取代传统逻辑开关,但是单片机技术复杂,编程难度高。而可编程控制器,它以控制功能强大,通用性好,编程简单易操作,控制稳定等特点正在成为电气自动控制系统中重要的开关量逻辑控制元件,并结合,声、光、电、液等信号采集元件和变频伺服技术成为电气自动控的核心部件。 相似文献
2.
为探究青藏高原典型高寒荒漠下垫面水分消耗规律,以2019年青藏高原典型高寒荒漠地区沱沱河站监测的涡动数据和微气象数据为基础,分析不同时间尺度蒸散值的变化特征和下垫面水分消耗特征,研究结果表明:小时平均蒸散发量最大值出现在14—15时,达0.46 mm·h-1;日蒸散值最大值出现在7月7日,为8.58 mm·d-1,最小值出现在4月2日,为0.30 mm·d-1;整个生长季蒸散值呈先增加后减小趋势,其中7月份最大,为120.68 mm,4月份最小,为64.80 mm;生长季总蒸散发量为581.15 mm,平均每天蒸散4.01 mm。整个生长季累计降水量为235.70 mm,蒸散发量与降水量(Precipitation,Pr)的差值(The difference between ET and Precipitation,IETP)显示,2019年青藏高原典型高寒荒漠植被生长季(4—8月)水汽交换以下垫面水分消耗为主。 相似文献
3.
宽幅高效离心式双圆盘撒肥机设计与试验 总被引:3,自引:0,他引:3
为解决现有水旱田撒肥机械作业效率低、撒肥量调节技术落后、施肥均匀性稳定性差等实际问题,设计了一种同轴驱动的离心式双圆盘撒肥机。介绍了整机结构与工作参数,研究设计了撒肥传动系统、撒肥盘结构、排肥量液压调节装置等,并确定了关键结构和参数,同时进行了试验研究。试验结果显示,推肥板推肥角度-20°~30°可调,撒肥幅宽达到50m,总排肥量稳定性变异系数低于6%,施肥均匀性变异系数低于16%。研究结果表明,撒肥机工作性能稳定、撒肥量可控、抛撒均匀,整机设计满足水旱田宽幅高效撒肥作业要求。 相似文献
4.
Tu Yaqing Li Zushu Huang Shanglian 《保鲜与加工》1993,(2):24-29
The idea for an expert system approach to the computer aided design of intelligent controllers (ESCAD1C) is discussed and the idea of two step modelling of an intelligent controller is presented on the basis of emulating human control behaviours to solve complex problems. The structure, functions and characteristics of ESCADTC system , and the design procedures of intelligent controllers are gived. The knowledge base and simulating functions for designing intelligent controllers are also described. 相似文献
5.
ZHANG Xin-yan 《保鲜与加工》2004,(5):54-56
While design the fuzzy controller, it is very important to determine the membership function of fuzzy variables.The data can be broadly classified as fuzzy sets by using the classification property of the BP neural network. The author selects a BP neural network with one hide layer and uses S function to the input and hide layer, and linear function to the output layer.Advanced BP algorithm isused to train the BP neural network in the environment of MATLAB . The nearer to the target values is the better the last output is.With the trained BP network , the membership values of the inputs can be got ten. This method has high rate and low error. 相似文献
6.
Hu Lide Yang Dan Wang Shilong 《保鲜与加工》1993,(6):58-64
After researching the function requirements of the planning and scheduling in manufacturing cells, the paper advanced a control structure with three phases, i. e. planning , scheduling and dispatching. The paper represented in detail the main purposes, requirements and scheduling actions in each phase. It suits to general machining FMSs. 相似文献
7.
8.
设计了Lagrange模糊插值控制器,对半主动悬架系统中减振器阻尼系数进行控制。通过MATLAB仿真分析表明,与基本模糊插值控制算法相比,采用该控制算法可提高控制的精度和改善控制效果。 相似文献
9.
Cover cropping is a common agro-environmental tool for soil and groundwater protection. In water limited environments, knowledge about additional water extraction by cover crop plants compared to a bare soil is required for a sustainable management strategy. Estimates obtained by the FAO dual crop coefficient method, compared to water balance-based data of actual evapotranspiration, were used to assess the risk of soil water depletion by four cover crop species (phacelia, hairy vetch, rye, mustard) compared to a fallow control. A water stress compensation function was developed for this model to account for additional water uptake from deeper soil layers under dry conditions. The average deviation of modelled cumulative evapotranspiration from the measured values was 1.4% under wet conditions in 2004 and 6.7% under dry conditions in 2005. Water stress compensation was suggested for rye and mustard, improving substantially the model estimates. Dry conditions during full cover crop growth resulted in water losses exceeding fallow by a maximum of +15.8% for rye, while no substantially higher water losses to the atmosphere were found in case of evenly distributed rainfall during the plant vegetation period with evaporation and transpiration concentrated in the upper soil layer. Generally the potential of cover crop induced water storage depletion was limited due to the low evaporative demand when plants achieved maximum growth. These results in a transpiration efficiency being highest for phacelia (5.1 g m−2 mm−1) and vetch (5.4 g m−2 mm−1) and substantially lower for rye (2.9 g m−2 mm−1) and mustard (2.8 g m−2 mm−1). Taking into account total evapotranspiration losses, mustard performed substantially better. The integration of stress compensation into the FAO crop coefficient approach provided reliable estimates of water losses under dry conditions. Cover crop species reducing the high evaporation potential from a bare soil surface in late summer by a fast canopy coverage during early development stages were considered most suitable in a sustainable cover crop management for water limited environments. 相似文献
10.
基于改进PSO算法的电机控制系统PID参数优化 总被引:1,自引:0,他引:1
粒子群算法(PSO,Particle Swarm Optimization)作为一种新型的随机优化方法,其算法结构简单,鲁棒性强,在组合优化和自适应控制等领域的非线性优化中有着广泛的应用前景.为此,提出一种改进的PSO优化算法,并将该算法应用于电机控制系统的PID参数优化设计.仿真结果表明,利用改进PSO算法优化的PID参数能有效改善控制系统的性能指标. 相似文献