Investigation into the Independent Metering Control Performance of a Twin Spools Valve with Switching Technology-controlled Pilot Stage

In hydraulic area,independent metering control(IMC)technology is an effective approach to improve system efficiency and control flexibility.In addition,digital hydraulic technology(DHT)has been verified as a reasonable method to optimize system dynamic performance.Integrating these two technologies into one component can combine their advantages together.However,few works focused on it.In this paper,a twin spools valve with switching technologycontrolled pilot stage(TSVSP)is presented,which applied DHT into its pilot stage while appending IMC into its main stage.Based on this prototype valve,a series of numerical and experiment analysis of its IMC performance with both simulated load and excavator boom cylinder are carried out.Results showed fast and robust performance of pressure and flow compound control with acceptable fluctuation phenomenon caused by switching technology.Rising time of flow response in excavator cylinder can be controlled within 200 ms,meanwhile,the recovery time of rod chamber pressure under suddenly changed condition is optimized within 250 ms.IMC system based on TSVSP can improve both dynamic performance and robust characteristics of the target actuator so it is practical in valve-cylinder system and can be applied in mobile machineries.

An Analysis of the Static and Dynamic Behavior of the Hydraulic Compensation System of a Multichannel Valve

Electro-hydraulic proportional valve is the core control valve in many hydraulic systems used in agricultural and engineering machinery.To address the problem related to the large throttling losses and poor stability typically associated with these valves,here,the beneficial effects of a triangular groove structure on the related hydraulic response are studied.A mathematical model of the pressure compensation system based on the power-bond graph method is introduced,and the AMESim software is used to simulate its response.The results show that the triangular groove structure increases the jet angle and effectively compensates for the hydrodynamic force.The steady-state differential pressure at the valve port of the new pressure compensation structure was 0.65 MPa.Furthermore,experimental results show that the pressure difference at the main valve port is 0.73 MPa,and that the response time is less than 0.2 s.It is concluded that the new compensation structure has good pressure compensation response characteristics.

油轮Manifolds及附属设备常见问题24问

在油轮的生产运营中,从初始的商务揽货问卷,填写Manifolds(货油管管头)及附属设备的相关参数;到靠泊前与码头的交换其参数;靠泊后接管和试压及完成货油的装卸;及随后的拆管,都少不了Manifolds及附属设备这个环节。

钠冷快堆中池式钠火的计算分析

文章论述了根据池式钠火的特点建立了理论模型 ,编制了SPOOL程序。该程序模拟钠燃烧过程中钠和氧气的化学反应 ,钠燃烧热在各种介质中不同方式的传递 ,钠气溶胶的产生、沉积 ,以及在各种通风条件下多种介质的质量和能量交换等瞬态过程 ,描述了钠燃烧过程中各种特征参数随时间的变化。其主要的计算参数包括房间内气体的压力和温度、房间建筑结构的温度、钠气溶胶质量浓度等等。用俄罗斯别洛雅尔斯克核电站实验和法国卡桑德拉 3号实验的数据 ,对SPOOL程序进行验证的结果表明 ,该程序的计算结果可信。

基于Oracle的数据交换技术研究

通过对各种数据导入与导出方式和应用软件的研究,提出了七种数据交换技术。这套方法还可推广到其他应用Oracle作为数据管理服务器的各类数据处理工作中,作为改善工作效率、提高数据处理速度的参考。

一个MS—DOS的SPOOLing系统

为MS-DOS操作系统设计一个专门的SPOOLing系统,以实现数据处理和I/O处理的并发进行,这是十分必要的。由于中文信息处理系统在I/O 方面的特点,所以这种系统更有必要配置 SPOOLing系统。本文介绍一个基于 MS-DOS的SPOOLing系统的设计和实现,包括它的总体结构、用户界面、数据结构和有关模块的算法。另外还对该系统的进一步升级作了讨论。事实证明,SPOOLing系统可大大提高整个系统的效率。

计算机运行模式的发展及其原因

计算机出现的半个世纪的时间里,随着操作系统地不断发展,计算机运行模式经历了巨大的变化。由最初的计算和输入输出在同一台机器上完成到采用批处理技术分离打印和计算,进而采用Spooling技术使I/O操作和计算完全并行。为了使多个作业同时运行,实现多用户共享,在分时系统的基础上实现了虚拟主机,达到了共享资源,降低费用的目的。随着计算机性能的提高,系统能够用一部分资源来处理人-计算机界面,用户界面设计开始引起人们的注意,嵌入式系统开始走入我们的生活。

操作系统中SPOOLING系统的分析与实现

如何实现低速字符设备与CPU或内存进行合理高效的信息交换是操作系统面临的一个常见问题。本文分析了SPOOLING系统在解决假脱机问题上相对于批处理和脱机方式的优点,并提出了如何在现有操作系统下对假脱机实现的初步构想。

2D DIGITAL SIMPLIFIED FLOW VALVE

The 2D digital simplified flow valve is composed of a pilot-operated valvedesigned with both rotary and linear motions of a single spool, and a stepper motor under continualcontrol. How the structural parameters affect the static and dynamic characteristics of the valve isfirst clarified and a criterion for stability is presented. Experiments are designed to test theperformance of the valve. It is necessary to establish a balance between the static and dynamiccharacteristics in deciding the structural parameters. Nevertheless, it is possible to maintain thedynamic response at a fairly high level, while keeping the leakage of the pilot stage at anacceptable level. One of the features of the digital valve is stage control. In stage control thenonlinearities, such as electromagnetic saturation and hysteresis, are greatly reduced. To a largeextent the dynamic response of the valve is decided by the executing cycle of the control algorithm.

Finite Element Numerical Simulation and PIV Measurement of Flow Field inside Metering-in Spool Valve

The finite element method （FEM） and particle image velocimetry （PIV） technique are utilized to get the flow field along the inlet passage, the chamber, the metering port and the outlet passage of spool valve at three different valve openings. For FEM numerical simulation, the stream function ψ-vorticity ω forms of continuity and Navier-Stokes equations are employed and FEM is applied to discrete the equations. Homemade simulation codes are executed to compute the values of stream function and vorticity at each node in the flow domain, then according to the correlation between stream function and velocity components, the velocity vectors of the whole field are calculated. For PIV experiment, pulse Nd： YAG laser is exploited to generate laser beam, cylindrical and spherical lenses are combined each other to produce 1.0 mm thickness laser sheet to illuminate the object plane, Polystyrene spherical particle with diameter of 30-50 μm is seeded in the fluid as a tracing particles, Kodak ES 1.0 CCD camera is employed to capture the images of interested, the images are processed with fast Fourier transform （FFT） cross-correlation algorithm and the processing results is displayed. Both results of numerical simulation and PIV experimental show that there are three main areas in the spool valve where vortex is formed. Numerical results also indicate that the valve opening have some effects on the flow structure of the valve. The investigation is helpful for qualitatively analyzing the energy loss, noise generating, steady state flow forces and even designing the geometry structure and flow passage.

Flow field simulation and establishment for mathematical models of flow area of spool valve with sloping U-shape notch machined by different methods

Precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke was derived. The computational fluid dynamics was used to analyze the flow features of the sloping U-shape notch on the spool, such as mass flow rates, flow coefficients, effiux angles and steady state flow forces under different operating conditions. At last, the reliability of the mathematical model of the flow area for the sloping U-shape notch orifice on the spool was demonstrated by the comparison between the orifice area curve derived and the corresponding experimental data provided by the test. It is presented that the bottom arc of sloping U-shape notch （ABU） should not be omitted when it is required to accurately calculate the orifice area of ABU. Although the theoretical flow area of plain bottom sloping U-shape notch （PBU） is larger than that of ABU at the same opening, the simulated mass flow and experimental flow area of ABU are both larger than these of PBU at the same opening, while the simulated flow force of PBU is larger than that of ABU at the same opening. Therefore, it should be prior to adapt the ABU when designing the spool with proportional character.

SPOOL图在管道设计中的应用

回顾配管图的发展历程,结合SPOOL图在国外工程的具体应用,介绍SPOOL图的绘制步骤,阐述SPOOL图的意义及具体应用。

Optical coherence transfer over 50-km spooled fiber with frequency instability of 2×10^(-17) at 1s

We demonstrate coherent transfer of an ultra-stable optical frequency at 192.8 THz over 50-km spooled fiber. Random phase noise induced by environmental disturbance through fiber is detected and suppressed by feeding a correctional signal into an acousto-optic modulator. After being compensated, the fiber-induced frequency instability is 2×10-17 at 1-s averaging time and reaches 8×10-20 after 16 h. The noise floor of the compensation system could be as low as 2×10-18 at 1-s averaging time.

Thermal-hydraulic modeling and analysis of spool valve with sloping U-shape notch by bond graph

To increase the efficiency and reliability of the thermodynamics analysis of the spool valve, the precise function expression of the flow area for the sloping U-shape notch orifice versus the spool stroke and thermal-hydraulic bond graph based on the conservation of mass and energy were introduced. Subsequently, the connection rule for the bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing the spool valve, the lumped parameter for mathematical model of the system was given. At last, the reliability of the mathematical model of the flow area and the thermal-hydraulic system for the sloping U-shape notch orifice on the spool were demonstrated by the test. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.

Calculation of Magnetic Field in J-TEXT with an Unsaturated Iron Core

A study of the magnetic field with an unsaturated iron core in tokamak equilibrium using a spool model is described in detail. The application of this model to the J-TEXT tokamak shows that the calculated results are in good agreement with those measured experimentally. At present this scheme is used to give the plasma configuration during J-TEXT＇s operation.

大型石化EPC项目国外工程公司管道试压包的编制

介绍了大型石化项目EPC总承包中,国外工程公司编制管道试压包的方法。

谈大型石化项目管道试压包的编制

论文主要研究大型石化项目中,工程公司是如何编制管道试压包的。

Study on a Novel Digital Electro－Hydraulic Pressure Valve with a Capillary Damping Tube Regulating Pressure

A digital electro-hydraulic 4-port differential pressure control valve with a novel principle and structure is presented. The valve is designed by applying the regulating pressure technique of a capillary damping tube and also making full use of double freedom of the spool motion. Thevalve can implement digitizing interface easily. The theoretical analysis and experimental resultsshow that the valve is not only very simple in structure and convenient in use, but also has manygood properties, such as fast response, no-null-shift, etc.

An optical fiber spool for laser stabilization with reduced acceleration sensitivity to 10^(-12)/g

Environmental vibration causes mechanical deformation in optical fibers, which induces excess frequency noise in fiber-stabilized lasers. In order to solve such a problem, we propose an ultralow acceleration sensitivity fiber spool with symmetrically mounted structure. By numerical analysis with the finite element method, we obtain the optimal geometry parameters of the spool with which the horizontal and vertical acceleration sensitivity can be reduced to 3.25 × 10^-12/g and 5.38 × 10^-12/g respectively. Moreover, the structure features the insensitivity to the variation of geometry parameters,which will minimize the influence from numerical simulation error and manufacture tolerance.