An Electro-Mechanical Controller for Adjusting Piston Pump Stroke On-the-Go for Site-Specific Application of Crop Nutrients

Nutrient application systems are designed to apply a relatively uniform amount of a fertilizer to agricultural fields. However, considerable variation in soil texture and other characteristics often occurs within and across production fields, which could have a major impact on fertilizer management strategies. Therefore, uniform application of a fertilizer over the entire field can be both costly and environmentally unsound. Due to their rugged and fool-proof design, crankshaft type piston pumps are widely used in agriculture. The on-the-go outlet flow of these pumps can only be varied by changing the drive shaft speed for each pump stroke setting. But only a limited range of flow rates can be achieved by changing the drive shaft speed. There is a need for an electronic controller, which can adjust the pump stroke on-the-go, for real-time, variable-rate application of crop nutrients. The Clemson “Electro-me-chanical controller for adjusting pump stroke on-the-go” was designed to replace the current manual stroke adjustment system on positive displacement piston pumps. This affordable system can be retrofitted on most John Blue - piston pumps for real-time adjustment of the pump stroke and can be controlled using pre-described position sequences (map-based) or real-time sensor commands (such as optical, pressure, and flow sensors) combined with fertilizer calculation algorithms. In addition, it can adjust pump stroke manually, using an eclectic dial from the tractor’s cab.

Output Characteristics of a Series Three-port Axial Piston Pump

Driving a hydraulic cylinder directly by a closed-loop hydraulic pump is currently a key research area in the field of electro-hydraulic control technology,and it is the most direct means to improve the energy efficiency of an electro-hydraulic control system.So far,this technology has been well applied to the pump-controlled symmetric hydraulic cylinder.However,for the differential cylinder that is widely used in hydraulic technology,satisfactory results have not yet been achieved,due to the asymmetric flow constraint.Therefore,based on the principle of the asymmetric valve controlled asymmetric cylinder in valve controlled cylinder technology,an innovative idea for an asymmetric pump controlled asymmetric cylinder is put forward to address this problem.The scheme proposes to transform the oil suction window of the existing axial piston pump into two series windows.When in use,one window is connected to the rod chamber of the hydraulic cylinder and the other is linked with a low-pressure oil tank.This allows the differential cylinders to be directly controlled by changing the displacement or rotation speed of the pumps.Compared with the loop principle of offsetting the area difference of the differential cylinder through hydraulic valve using existing technology,this method may simplify the circuits and increase the energy efficiency of the system.With the software SimulationX,a hydraulic pump simulation model is set up,which examines the movement characteristics of an individual piston and the compressibility of oil,as well as the flow distribution area as it changes with the rotation angle.The pump structure parameters,especially the size of the unloading groove of the valve plate,are determined through digital simulation.All of the components of the series arranged three distribution-window axial piston pump are designed,based on the simulation analysis of the flow pulse characteristics of the pump,and then the prototype pump is made.The basic characteristics,such as the pressure,flow and noise of the pumps under different rotation speeds,are measured on the test bench.The test results verify the correctness of the principle.The proposed research lays a theoretical foundation for the further development of a new pump-controlled cylinder system.

Automatic Control of Water Pumping Stations

Automatic Control of pumps is an interesting proposal to operate water pumping stations among many kinds of water pumping stations according to their functions.In this paper,our pumping station is being used for water supply system. This paper is to introduce the idea of pump controller and the important factors that must be considering when we want to design automatic control system of water pumping stations. Then the automatic control circuit with the function of all components will be introduced.

阀-泵并联变模式液压调速系统设计与实验研究

提出并设计了阀-泵并联变模式液压调速系统,其可以在不同的调速阶段,采用不同的控制模式,而且还可以调节泵控和阀控在联合调速中的权重比,以提高系统的综合调速性能。搭建了实验系统,进行了一个调速周期的实验研究。实验结果表明,在调速过程中,不同控制模式之间切换平滑,比例阀和变量泵的变化规律符合预期,阀-泵权重比设置合理,提高了调速系统的综合调速性能。阀-泵并联变模式控制,使阀控与泵控协调工作,提高了液压调速系统的灵活性和适应性,丰富了目前液压系统的调速方式。

Role of non-steroidal anti-inflammatory drugs on intestinal permeability and nonalcoholic fatty liver disease

The use of non-steroidal anti-inflammatory drugs(NSAIDs) is widespread worldwide thanks to their analgesic, anti-inflammatory and antipyretic effects. However, even more attention is placed upon the recurrence of digestive system complications in the course of their use. Recent data suggests that the complications of the lower gastro-intestinal tract may be as frequent and severe as those of the upper tract. NSAIDs enteropathy is due to enterohepatic recycling of the drugs resulting in a prolonged and repeated exposure of the intestinal mucosa to the compound and its metabolites. Thus leading to so-called topical effects, which, in turn, lead to an impairment of the intestinal barrier. This process determines bacterial translocation and toxic substances of intestinal origin in the portal circulation, leading to an endotoxaemia. This condition could determine a liver inflammatory response and might promote the development of nonalcoholic steatohepatitis, mostly in patients with risk factors such as obesity, metabolic syndrome and a high fat diet, which may induce a small intestinal bacterial overgrowth and dysbiosis. This alteration of gut microbiota may contribute to nonalcoholic fatty liver disease and its related disorders in two ways: firstly causing a malfunction of the tight junctions that play a critical role in the increase of intestinal permeability, and then secondly leading to the development of insulin resistance, body weight gain, lipogenesis, fibrogenesis and hepatic oxidative stress.

Mixed Conduction in BaCe0.8Pr0.2O3-α Ceramic

BaCe0.8Pr0.2O3-α ceramic was synthesized by high temperature solid-state reaction. The structural characteristics and the phase purity of the crystal were determined using powder X-ray diffraction analysis. By using the methods of AC impedance spectroscopy, gas concentration cell and electrochemical pumping of hydrogen, the conductivity and ionic transport number of BaCe0.8Pr0.2O3-α were measured, and the electrical conduction behavior of the material was investigated in different gases in the temperature range of 500-900℃. The results indicate that the material was of a single perovskite-type orthorhombic phase. From 500℃ to 900 ℃, electronic-hole conduction was dominant in dry and wet oxygen, air or nitrogen, and the total conductivity of the material increased slightly with increasing oxygen partial pressure in the oxygen partial pressure range studied. Ionic conduction was dominant in wet hydrogen, and the total conductivity was about one or two orders of magnitude higher than that in hydrogen-free atmosphere （oxygen, air or nitrogen）

基于自校正水泵模型的空调系统冷水泵压差前馈-反馈控制方法

在空调冷水系统运行过程中,冷水泵的运行频率需要根据实时系统工况进行调节。传统本地控制器一般使用PID反馈控制算法,基于被控变量(压差/温差)与设定值之间的偏差来调整水泵的运行频率。然而该算法的控制质量受PID参数整定准确性的影响较大。为解决该问题,提出了一种基于自校正水泵模型的空调系统冷水泵压差前馈-反馈控制方法。在被控变量和设定值出现较大偏差时,该方法可利用自校正的水泵扬程曲线与相似律快速计算出水泵应被调整至多大频率。使用某地铁站空调系统的实际运行数据作为模拟输入,对该控制方法下水泵的运行情况进行了模拟。结果显示,该方法的控制精度与基于单神经元的自适应增量式PID反馈控制基本一致,但该方法可简化对参数的整定工作,减少控制质量对参数整定的依赖。

模糊-PI控制在高压消防给水系统中的应用

高压消防给水系统主要依靠稳压系统来保证管网中最不利点的流量和水压,稳压系统的性能决定了高压消防给水系统的可靠性和稳定性。模糊控制器有良好的鲁棒性且反应速度快,而PI调节器能够消除稳态误差,实现无差调节。针对高压消防给水系统大滞后及非线性等对消防管网工作性能的不利影响,构建了一种模糊-PI双模控制模型,以提高消防给水系统的稳定性和可靠性。实验结果表明,与常规的PI控制及模糊控制相比,该控制模型不仅结构简单,而且具有优良的控制品质和性能。

Complete Coronary Revascularization with on Pump Beating Heart

Background Off-pump coronary artery bypass grafting (CABG) is becoming increasingly popular world - wide. But it is not always feasible. Current cardioplegic techniques do not consistently avoid myocardial ischemic damage. So we use on pump beating heart technique to supplement off-pump CABG. Methods Based on 860 off-pump CABG cases between Aug 1998 to Aug 2000. From Aug 1999 to Aug 2000, 46 CABG cases were performed with on pump beating heart technique at Mani-pal Hospital Heart Foundation, Bangalore, India. All surgeries were performed through a median sternotomy. Exposure techniques were tailored to individual vessels and cardiac regions and local immobilization was performed with octopus. Vascular control was achieved with occluders and shunts. Total cardiopulmonary bypass (CPB) was established before or during CABG and normolthemia was used. Results Among 46 on -pump beating heart CABG patients, 26 patients used CPB before or during OP - CABG because of unstable hemodynamics and electric instability , 7 had very deep intramyocardial left anterior descending arteries, 5 patients had poor LV function (LVEF < 30 % ), 8 patients had cardiomegaly. The average number of grafts was 3.5. No operative mortality. Three patients had postoperative myocardial infarction. Anesthetic time 4. 5±1. 2 hours, extubation time 10±2. 5 hours, blood lost 680±230 mL, blood requirement 540±150 mL, preoperative LVEF 50. 3±13 % , postoperative LVEF 64. 1±14 %, ICU stay 1. 5±0. 5 days, hospi- tal stay 9.2±1.8 days. Conclusion Complete coronary revascularization with on pump beating heart is a supplement for off - pump CABG when it is not feasible. It eliminates intraoperative globe myocardial ischemia and avoids transient myocardial injury during cardioplegic arrest and myocardial reperfusion.

GB 50974-2014实施后的消防电气设计探讨

结合GB 50974-2014《消防给水及消火栓系统技术规范》的实施,分析和探讨其中与电气相关的主要条文要求,包括压力开关/流量开关直接启动消防水泵、消防控制柜或控制盘应能显示消防水池/高位消防水箱等水源的正常水位、消防水泵控制柜的IP等级、机械应急启泵、消防水泵巡检等。

GMB200-2.5型隔膜泵机组设计要点分析

隔膜泵的冲次n和隔膜直径D为影响隔膜泵性能和结构的主要参数。本文主要介绍隔膜泵机组技术参数的合理匹配以及隔膜行程控制系统设计分析。

水产养殖工厂太阳能-海水源热泵系统水体调温性能研究

该文在对比传统水体温度提升技术的基础上,将太阳能光热利用技术与海水源热泵技术相结合,提出一种太阳能-海水源热泵水体调温系统。研究结果表明,该系统能够有效提升冬季养殖水体温度,其中废热回收子系统中废热回收利用效率最高可达78%,该部分对提升海水温度的贡献率最大,为53%;海水源热泵子系统对养殖海水温升贡献率其次,为43%;太阳能辅助升温子系统对养殖海水温升贡献率最小,为4%。另外,太阳能-海水源热泵系统节能效益显著,与燃煤锅炉、燃气锅炉、燃油锅炉、电锅炉和空气源热泵等传统养殖用水温度提升技术相比,太阳能-海水源热泵在冬季可分别节省53%、77%、80%、90%、65%的运行费用。

泵控马达液压系统压力拍振成因及其动态分析

针对液压系统中泵和马达的压力脉动频率相近时影响输出稳定性和负载工作可靠性的问题,采用AMESim多学科仿真软件对多能域耦合闭式液压系统进行物理建模,研究不同柱塞副间隙下拍振现象的规律特性。通过计算泵控马达液压系统的阻尼比及分析蓄能器模固有频率,提出利用蓄能器对压力拍振现象进行测试和分析。最后,通过搭建机电液一体化实验平台对仿真分析进行验证。理论分析和实验结果均表明:压力拍振对于压力信号和柱塞磨损等液压系统常见故障的故障特征有明显放大作用,蓄能器对于液压系统压力拍振幅值有明显的缓冲作用。

低温季节泵送混凝土结构施工期温控防裂研究

低温季节施工时针对泵闸等结构泵送混凝土防冻与防裂的技术难题,以SYG工程为例,结合工程实际施工过程及现场温控监测成果进行大体积泵送混凝土温控防裂反馈分析;对比分析了不通水工况与实际通水工况下的应力曲线与混凝土容许拉应力曲线,并结合现场温控过程中存在的主要问题探讨了低温季节下泵闸工程的温控防裂技术.结果表明,在-8℃的较低温度下,采取充分的水管冷却和严格的表面保温措施可有效控制结构内部最高温度、内外温差以及最大拉应力水平,减小水闸结构开裂风险.本工程温控实践经验可为类似条件下的泵闸工程提供参考.

基于泵泄漏模型的双泵源流量控制系统

目前,泵阀协同压力流量复合液压控制系统在流量控制模式和压力控制模式之间切换时,由于过流匹配,系统会产生压力冲击和能量损失。为解决这一问题,基于泵的泄漏模型,提出一种由伺服电机作动力源的内啮合齿轮定量泵和三相同步电机拖动的电液比例变量泵组成的双泵源流量控制系统。建立基于泵泄漏模型的双泵源流量控制系统的AMESim和Simulink联合仿真模型,对新的控制策略进行验证。结果显示:以伺服电机驱动内啮合齿轮泵作为补偿泵的双泵源流量控制系统,由流量控制模式切换到压力控制模式时,压力冲击降低30.7%,流量波动减小58.3%;由快速模式切换到微动模式时,模式切换所用时间减少62.5%;当负载发生突变,快速模式可以有效补偿系统泄漏量,且系统的流量波动减小2.68%;在微动模式下,系统的流量波动减小10.86%,比传统的泵阀协同压力流量复合液压控制系统速度稳定性提高。

潜油电泵控制柜故障分析与解决对策

潜油电泵控制柜是海上油田地面工程的重要控电设备。潜油电泵控制柜控制着海上潜油电泵井的启停和保护,发生故障时会导致油井生产异常或停井,会严重影响原油产量,带来很大维修成本。为此,文章对近年以来潜油电泵控制柜故障进行了统计分析,对故障排查和解决对策提出了建议,降低了油井故障率,保障了海上原油平稳生产,为下一步海上电泵井管理提供经验。

消防水泵启动控制方式分析和有关争议的讨论

深入分析了现行标准对消防水泵启动控制方式的要求,阐明了消防水泵不同启动控制方式之间的关系,明确了不同消防给水系统应设置的消防水泵启动控制方式,并对可能影响消防水泵启动的有关争议问题进行了讨论,给出不必纠结于流量开关和压力开关谁应该先启动,以及流量开关的设置位置的结论。要求消防水泵控制柜应随时处于被监控状态,并对制定消防水泵控制柜产品标准提出了建议。

循环水泵节能方式的应用与对比

针对循环水泵能耗高的问题,分析变频调速、定制高效泵、自主选型改造、水泵运行模式优化、高分子涂层技术等不同节能方式在钢铁企业中的应用场景,并对比不同节能方式的优缺点,可为各工序循环水系统节能方式的选择提供参考。

单双泵控混合分布式挖掘机液压系统性能分析

针对泵控非对称缸中存在流量不平衡问题和挖掘机(动臂、斗杆及铲斗)各液压缸的多象限工况,提出一种单双泵控混合分布式挖掘机液压系统。基于挖掘作业时工作装置的各液压缸速度-负载特性,为二象限工况的动臂设计单泵控液压单元,四象限工况的斗杆及铲斗设计双泵并联式泵控液压单元。以微型挖掘机为对象,在MATLAB/Simulink中建立多体动力学模型和液压系统模型,设计PID位置控制器,在典型挖掘工况下进行仿真分析。结果表明:单泵式的效率与双泵并联式的基本相当,但后者在负载力突变时,几乎不产生速度波动;在典型挖掘工况下,所提出的单双泵控混合分布式挖掘机液压系统的总效率为62%。

泵站停泵水锤事故溯源分析及防护

为研究两阶段缓闭止回阀关阀时间及类型对停泵水锤的影响,以蓝山县高塘坪分置式抽水蓄能工程中的泵站为例,基于两阶段缓闭止回阀工作原理,采用数值模拟方法溯源分析停泵水锤事故产生原因,并对比不同工况下液控蝶阀及多功能水泵控制阀在相同总关阀时间下的停泵水锤防护效果。结果表明,液控蝶阀关阀规律不合理是导致停泵水锤事故的主要原因;与液控蝶阀相比,多功能水泵控制阀在不同工况下的一阶段零流速的自适应关阀方式,可显著降低停泵工况下的水锤峰;经现场实测获取更换多功能水泵控制阀后的停泵水锤曲线,多功能水泵控制阀有效地解决了泵站水锤防护问题,提升了泵站的安全韧性。