TRANSIENT RESPONSE OF A VALVE CONTROL HYDRAULIC SYSTEM WITHLONG PIPES

The simulation model of a valve control hydraulic system with long pipe isestablished in Simulink4.0, and then the step responses of the systems with difference pipeparameters are investigated by simulation. Simulation results show that the long pipes will slowdown the step response of system and make it fluctuate periodically. The results of simulationconform to the results of experiment on the whole, which proves the mathematic model is correct.

Fuzzy Theory Based Control Method for an In-pipe Robot to Move in Variable Resistance Environment

Most of the existing screw drive in-pipe robots cannot actively adjust the maximum traction capacity, which limits the adaptability to the wide range of variable environment resistance, especially in curved pipes. In order to solve this problem, a screw drive in-pipe robot based on adaptive linkage mechanism is proposed. The differential property of the adaptive linkage mechanism allows the robot to move without motion interference in the straight and varied curved pipes by adjusting inclining angles of rollers self-adaptively. The maximum traction capacity of the robot can be changed by actively adjusting the inclining angles of rollers. In order to improve the adaptability to the variable resistance, a torque control method based on the fuzzy controller is proposed. For the variable environment resistance, the proposed control method can not only ensure enough traction force, but also limit the output torque in a feasible region. In the simulations, the robot with the proposed control method is compared to the robot with fixed inclining angles of rollers. The results show that the combination of the torque control method and the proposed robot achieves the better adaptability to the variable resistance in the straight and curved pipes.

The Vibration Controllability of 20~# Steel Pipe Excited by Unsteady Flow

An excited experiment system of 20# steel pipe was established with oil cylinder, 20# steel pipe, frequency converter, pump station and wave exciter generating unsteady flow artificially. The experimental results showed that the 20# steel pipe could vibrate with the excitation of unsteady flows, and the vibration was periodic, instead of a harmonic one. Particles on the front and rear positions of pipe vibrated synchronously, and the vibration intensity of the pipe＇s two ends was greater than in the middle. System pressure and wave exciter＇s frequency had much influence upon pipe＇s amplitude. Pipe＇s vibration frequency was little affected by system pressure, and its value was close to the wave exciter＇s. Therefore, the active control of pipe＇s vibration can be realized by setting system pressure and adjusting frequency converter＇s frequency.

Quality Control on Crimping of Large Diameter Welding Pipe

Crimping is used in production of large diameter submerged-arc welding pipes. Many researches are focused on crimping in certain manufacturing mode of welding pipe. The application scopes of research achievements become limited due to lack of uniformity in theoretical analysis. In order to propose a crimping prediction method in order to control forming quality, the theory model of crimping based on elastic-plastic mechanics is established. The main technical parameters are determined by theoretical analysis, including length of crimping, base radius of punch, terminal angle of punch, base radius of die, terminal angle of die and horizontal distance between punch and die. In addition, a method used to evaluate the forming quality is presented, which investigates the bending angle after springback, forming force, straight edge length and equivalent radius of curvature. In order to investigate the effects of technical parameters on forming quality, a two-dimensional finite element model is established by finite element software ABAQUS. The finite element model is verified in that its shapes error is less than 5% by comparable experiments, which shows that their geometric precision meets demand. The crimping characteristics is obtained, such as the distribution of stress and strain and the changes of forming force, and the relation curves of technical parameters on forming quality are given by simulation analysis. The sensitivity analysis indicates that the effects of length of crimping, technical parameters of punch on forming quality are significant. In particular, the data from simulation analysis are regressed by response surface method （RSM） to establish prediction model. The feasible technical parameters are obtained from the prediction model. This method presented provides a new thought used to design technical parameters of crimping forming and makes a basis for improving crimping forming quality.

STUDY ON USING SERIAL PIPE TO IMPROVE THE DYNAMIC RESPONSE OF ELECTRO－HYDRAULIC SPEED CONTROL SYSTEM

The mathematical models of electro-hydraulic speed control system using series of pipesis presented. The principle of pipe effection on dynamics of the system is developed. Computersimulation and physical experiment are also carried out. The experimental results show that a rightchoosing of serial pipe for electro-hydraulic system enables the dynamic response of the system tobe improved effectively.

Analytic study on the optimal control of water hammer waves in pipes

To realize the accurate control of water hammer in pipes by valve stroking, based on basic differential equations of water hammer subjected to initial and boundary conditions, the traveling solution of wave equations in finite region was applied to the linear water hammer problem. With the given velocity function at the valve and the introduction of curve integration independent of integral path, the exact analytic solution of dimensionless water hammer pressure was obtained in the course of valve closing. Based on the definition of eigen wave height, optimal eigen wave height and observation time, the control goal of water hammer pressure and the judgment rule of the optimal eigen wave height were determined, then the optimal velocity function in the calculated example was derived, which can reduce the water hammer pressure maximally. According to this function, a valve closing program was set, and the optimal control of water hammer could be realized.

Vibration and Control of Pipes Conveying Fluid

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鄱阳湖圩堤管涌险情分析与防治措施

为了进一步防治管涌险情,以鄱阳湖防洪圩堤为研究对象,建立了管涌预测的理论模型,运用GeoStudio2018软件对防洪圩堤进行模拟分析,设置了降雨强度、降雨类型和降雨时刻三个关键因素和四种工况,分别用Seep/W模块和Sigma/W模块对防洪圩堤进行破坏计算。结果表明,只有在固定库水位下不同降雨会出现管涌现象,管涌出现破坏的有固定库水位23 m+降雨时刻20~30 d+降雨强度0.06 m/d,管涌点位于下游坡坡脚0.2 m处;提出了反滤铺盖方案,并建立了相应的数值模拟模型。经验证,该方案符合相关规范要求。

企业数字化转型对环境社会责任的影响研究--“末端治理”还是“源头控制”?

本文基于2006—2020年我国A股上市企业数据,考察企业数字化转型对企业环境社会责任的影响及机制。研究发现:企业数字化转型对企业“源头控制”环境社会责任有显著正向影响,对“末端治理”环境社会责任有显著负向影响,并实现了企业从“末端治理”向“源头控制”的转变。实证结论在经一系列稳健性检验与内生性处理后依然成立。机制分析发现,数字化转型能通过员工绿色行为、企业环境社会关注意愿及全要素生产率影响企业的环境社会责任。调节效应发现,公司治理与融资成本能进一步调节数字化转型对两种环境社会责任的影响。异质性分析发现,数字化转型对非国有、高环境规制及高学历高管在承担“源头控制”环境社会责任上有着更显著的影响。动机分析发现,企业之所以从“末端治理”向“源头控制”环境社会责任的转变,其动机在于后者对企业价值有着更为显著的正向影响,而数字化转型在其中会进一步强化这一影响。

含汞油气田汞腐蚀与控制技术现状

介绍了含汞油气田在国内外的分布和汞含量的情况,以及汞在油气田中常见的存在形态与特性,阐述了金属及其合金的4种腐蚀破坏机理,系统调研了国内外汞及其化合物对油气田管道与设备的常见金属及其合金的腐蚀特征与控制技术研究与应用现状,提出今后需要加强含汞油气田腐蚀与污染及其防护的研究与应用的方向或问题。

基于自整定模糊PID的柔性管道加热控制系统研究

针对传统温度控制器调节控制精度低、超调量大的缺点,设计了一套模糊控制策略+比例积分微分(PID)控制方法+物联网云平台技术的柔性管道加热控制系统。该系统可实现过程实时监控、温度检测和闭环控制功能,使输气管道在加热过程中的温度控制稳定、温度调节响应速度快、超调量小。通过对控制过程的可视化,可实时分析系统运行状况,从而实现对加热过程和气体输送过程的动态监控。该系统具有加热及温度控制、运行状态实时监测功能。适用于管道加热系统的柔性管道加热控制系统对半导体企业降低生产能耗、提高生产效率、过程监控、保证输送系统安全和平稳运行有重要意义。

高填方大直径钢波纹管涵变形机制与控制技术研究

目的 研究高填方大直径钢波纹管涵变形机制与控制技术,解决其结构变形过大的问题。方法 基于管道压缩变形公式,提出在管涵两侧一定范围内填筑水泥土材料的新技术;通过室内试验确定水泥土材料中最优水泥质量分数,再基于数值模拟和现场试验分析采用新技术施工的管涵结构的受力及变形特征及其上部竖向土压力分布规律,确定最优管侧填筑范围。结果 新填筑技术能充分利用水泥土的刚度限制管涵的变形,当管涵两侧2/3管径范围内采用水泥质量分数为8%水泥土回填时,管涵的最大竖向及水平变形分别减少了35.1%和55.0%,结构最大应力也由管顶处转移至管涵上部45°附近,受力更为合理。结论 新填筑技术使管涵更好地与周围土体逐步变形协调,产生荷载重分布形成土拱效应,将管顶土压力由管中心向管边缘处转移,有效减小了钢波纹管涵结构变形和应力集中。

L360N无缝管线钢管的控轧控冷生产工艺开发

某PQF连轧管机组生产Ф273 mm×8 mm规格L360N无缝管线钢管时,采用常规热轧、控制轧制、控制轧制+控制冷却三种方式组织生产,分析了这三种工艺生产的无缝钢管的性能与组织差别。工业试验表明,控制轧制+控制冷却可以明显细化晶粒,在提高钢管拉伸性能的同时,可大幅提高钢管的冲击韧性,合理的控轧控冷工艺可使钢管稳定满足-30℃冲击值的要求。

工业聚集区内污水管道病害研究进展

工业废水成分复杂、污染水平较高,即使经过预处理仍可能对连接排水系统造成一定影响。现阶段针对工业聚集区内污水管道性能退化和病害的研究相对较少。本文以H市典型工业聚集区内的管道现状为调研对象,阐明在工业聚集背景下管道病害的基本分布情况,围绕沉积、结晶、腐蚀和破坏等功能性和结构性病害,系统性地探讨病害产生原因,明确工业聚集背景下病害发生的不同,并分析不同病害之间的相互作用机制。基于此,构建病害控制的针对性策略,为工业聚集背景下管道系统的稳定运行提供技术参考。

薄壁大口径钢管弯管成型变形控制工艺

制作超轻越野车车身骨架的钢管因材质特殊、口径大、管壁薄,弯管成型后截面变形严重,导致尺寸严重超差,严重影响车身整体尺寸精度和结构强度。对此,进行原因分析,并提出薄壁大口径钢管弯管成型变形控制工艺。介绍了工艺原理和应用效果。这一工艺可以减小薄壁大口径钢管弯管成型的截面变形量。

次级源和误差传感器布放对带弹性障板的充液直管声振复合有源控制的影响

针对充液管路系统噪声有源控制问题,研究了次级源和误差传感器布放对带弹性障板的充液直管管路系统有源消声与有源消振复合控制效果的影响。基于声固耦合方法建立了带弹性障板的充液直管管路系统的有限元模型,在声激励下对比了次级声源布放对系统有源消声性能的影响,并在组合激励下分析了次级力源、次级声源和误差传感器布放对系统复合有源控制的影响。结果表明,非对称分布的次级声源容易激起管壁振动,进而带动障板振动,导致有源消声效果不佳;采用对称分布的次级声源可使低频段的降噪量提高10 dB以上。复合有源控制可进一步提升全频段的控制效果。通过增加振动误差传感器数量,可使绝大多数频点的降噪量提高1∼20 dB不等。此外,在管壁上布放的两圈次级力源的间距小于管壁振动波长的1/4,且都不位于管壁振动节点附近时控制效果更好。

双层合采油井盲管控水机理数值模拟

依托胜利油田盲管控水先导开发试验项目,根据双层合采油井油水流入动态特征,建立了双层合采油井盲管控水模型,并利用Fluent软件开展不同长度与不同位置盲管作用下的双层合采油井地层产液特征数值模拟研究。结果表明:盲管可以增加高含水层的井底流压,降低地层产液流量。对于综合含水率达到80%的双层合采油井,盲管长度是影响其控水效果的主要因素,盲管越长,控水效果越明显。与无盲管相比,在2 m的高含水层全段放置盲管,产液含水率可降低30百分点。盲管位置是影响其控水效果的次要因素,在2 m的高含水层不同位置放置0.5 m盲管,产液含水率下降约3百分点。为保障控水效果,应针对高含水层所在位置,放置适应地层厚度的盲管,调控双层合采油井产液流量,达到控水的目的。在优化双层合采油井盲管长度和盲管位置的基础上,利用流体数值模拟对盲管的控水机理进行了深入研究,研究结果能为高含水油藏双层或多层合采油井实施盲管控水开采提供技术指导。

基于LSTM的试验系统控制策略设计

发动机试验是航空发动机开发与设计中的重要环节,空气管道系统作为发动机实验测试系统,发挥着重要作用。该文针对传统的人工调节先输出后反馈再控制的策略存在控制滞后、依赖调节经验的问题开展控制策略研究。构建压力试验系统的参数预测神经网络模型;以试验系统的目标压力和目标流量为依据,约束阀门调节方向,遍历所有的阀门开度生成策略表;将策略输入到预测模型,利用预测结果结合策略选取规则,得到最终的阀门调节策略。经过仿真与试验测试,该文提出的阀门调节策略将试验控制效率至少提高了30%,并且流量、压力控制精度优于1%。

局部土地利用类型变化对城市水文过程的影响研究

为探究城市下垫面局部土地利用类型变化对城市水文过程的影响,采用高效高精度城市雨洪模型(GAST)耦合管网模型(SWMM),模拟不同降雨重现期下动态改变土地利用类型(单块无下渗土地C_(1)、多块组合无下渗土地C_(2)、单块裸土地C_(3)、单块草地C_(4)和单块林地C_(5))对城市地表积水、管网排水的影响。结果表明:改变局部原始土地利用类型(B1)在小降雨重现期下降低了城市积水量,而在大降雨重现期下改变土地下渗面积和区域位置无法进一步减少积水,此时则需考虑非工程措施的极端暴雨应对模式。不同动态规划区域下渗强度导致管网排口流量增幅不同(C_(2)>C_(1)>C_(3)>C_(4)>C_(5)),隔渗能力越强对管网排口流量增幅影响越大,而管网径流控制率则呈相反趋势。结合对积水量的影响可知,增加下垫面下渗能力并结合排水系统可进一步降低城市内涝风险和管网排水负荷,且管网径流控制率同样可以作为评估动态规划可行性的一个重要指标。