炉顶液压系统热响应的计算机仿真

提出了炉顶液压系统热响应模型的建立方法,推导出其热平衡方程,建立了热响应模型,并对其进行了计算机仿真。通过仿真结果,分析了高温工作环境下液压系统温升规律,分析了系统动特性对热响应过程的影响。介绍了现场实地测试结果,进一步验证了上述分析的正确性,对高温工作环境下的液压系统设计与使用提供一定的参考作用。     

AMESim仿真技术在换管机液压系统中的应用

提出一种新型液压地下换管机,介绍其结构组成,分析其液压系统工作原理。运用液压/机械仿真软件AMESim对给进/回拖机构液压系统进行建模与仿真,分析了影响液压系统动态特性的主要参数,得出液压系统的动态特性曲线,对后续全自动液压地下换管机物理样机的改进试制具有理论依据和参考价值。     

液压系统中液压冲击的分析及其防止和减轻措施

文章结合液压系统设计和生产实践,对液压系统中的液压冲击进行了全面的分析,阐述了一些防止和减轻液压冲击的措施。     

泰国BNS棒材工程液压系统的设计

本文介绍了棒材生产线液压系统及其设计，并对液压系统设计中的几个值得注意的问题进行了分析与探讨。     

液压节能技术在高线生产中的应用

以邢钢高线生产为例,分析和介绍了液压系统在原理设计和实际生产中采用的节能技术,为液压系统设计人员和设备管理人员提供一些参考经验。     

大型电渣重熔设备横臂液压系统DSHplus仿真研究

大型电渣炉的横臂升降控制采用液压系统实现。横臂下降过程是电渣冶金的给料过程,其控制过程直接决定了电渣冶金的产品质量。针对120 t大型电渣炉横臂升降液压系统,采用DSHp lus系统仿真软件,对液压系统的关键参数及运动性能进行了仿真研究,验证了系统设计的合理性。     

典型冷轧带钢处理线液压系统设计

现代化大型冷轧带钢处理线的生产速度快、自动化程度高.良好的液压系统设计是现代冷轧带钢处理线技术总成和设计的重要环节.以宝钢分公司冷轧厂某新建彩涂机组的液压系统设计为例,通过对液压系统设计原则、生产工艺、设备总体设计的特点的分析,计算选择液压系统的压力和流量等参数,设计系统回路,说明该液压系统的设计思想.按照本设计建成的液压系统,经长时间生产使用,证明完全符合现代冷轧带钢处理线的工艺要求.     

邯钢CSP线热轧机液压AGC仿真分析

液压AGC是现代板带厚度控制的关键技术之一.以邯钢连铸连轧厂热轧机组液压AGC系统为对象,利用大型通用分析软件--Matlab对系统的时域和频域特性进行了分析研究.在此基础上研究了系统各主要因素对系统动态特性的影响.     

大功率圆锥破碎机液压系统设计与仿真

基于圆锥破碎机的液压系统工作原理和各元器件选型,运用AMESim软件建立了圆锥破碎机液压系统的仿真模型,得到了破碎机定锥锁紧、过铁释放与清腔和排矿口大小调节三大支路执行系统负载、流量以及工作压力随时间的变化曲线,结果表明：液压系统在外部复杂条件下仍能有效地工作,从而验证了液压系统设计的合理性。     

冷床液压系统的典型故障分析

对弧形CCM冷床液压系统的典型故障从理论和实践上进行了分析,指出了系统设计和设备维护中存在的不足,并提出了系统改进和设备维护措施。     

新型高炉炉前移盖机

国内外高炉生产实践证明,移盖机是现代化大型高炉实现炉前机械化不可缺少的关键设备之一。结合国内大中型高炉风口平台出铁场炉前移盖机的结构设计特点和现场运行情况,介绍一种已投入工业化应用的新型全液压炉前移盖机,并详细阐述了其机械和液压系统构成、机构设计原理、运动特征分析和关键计算分析。     

Dynamic Modeling of Hydraulic Shovel Excavators for Geomaterials

The hydraulic shovel excavator has found significant applications in surface mining, construction, and geotechnical operations due to its flexibility and mobility. The key to high availability and utilization of this shovel is adequate understanding of machine dynamics and machine-formation interactions among other technical, operating, safety, and economic factors. These shovels are capital intensive, complex in design and operation within severely constrained environments. Detailed dynamic modeling and analysis are required to understand their effective utilization for achieving efficient operating performance and economic useful lives. Previous attempts at solving these problems are limited because they do not provide knowledge on the resistive forces and moments for efficient excavation. In this paper, the Newton-Euler techniques are used to develop hydraulic shovel dynamic models with numerical examples. Detailed analysis of the results shows that: (1) the kinematics of the stick-bucket joint (joint 3) is the most critical and effective control of this joint and is important input into efficient excavation design and execution; and (2) the highest resistive moments occur between the duration of 1.5 and 2.0?s after the start of formation excavation and the highest magnitudes are 1,500?Nm (for stick), 900?Nm (for bucket), and 600?Nm (for boom). Based on these results, the path trajectories, dynamic velocity and acceleration profiles, and dimensioned parameters for optimum feed force, torques, and momentum of shovel boom-bucket assembly can be modeled and used for efficient excavation. The optimum digging forces and resistances for the hydraulic shovel excavator can also be modeled and used to predict optimum excavation performance.     

Research in Modeling and Simulation for Improving Construction Engineering Operations

Construction simulation, a fast-growing field, is the science of developing and experimenting with computer-based representations of construction systems to understand their underlying behavior. This paper provides a history of construction simulation theory, explores the CYCLONE modeling methodology and its major subsequent developments, examines the development of the Simphony.NET and COSYE modeling environments and their functionality as more generic simulation platforms, and reviews effective strategies for applying simulation in construction. A construction simulation case study is presented that illustrates one successful approach for adopting simulation technology in the industry and outlines the benefits to industry of integrating these technologies. The paper provides an overview of long-term simulation initiatives leading to the next generation of computer modeling systems for construction, where simulation plays an integral role in a futuristic vision of automated project planning and control.     

Pool Quality Index: New Method to Define Minimum Flow Requirements of High-Gradient, Low-Order Streams

High-gradient (>1%), low-order streams, characterized by hydraulically nonuniform and heterogeneous channels, represent a problem for the most widely employed habitat-based in-stream flow methods (IFIM-PHABSIM). In a nonuniform high gradient and turbulent channel, as low-order streams usually are, the classical 1D hydraulic modeling, ordinarily employed by in-stream flow models to simulate the changes in fish habitat with the flow, could be questionable, if not completely inapplicable. Channel morphology in fact plays a major role in association with hydraulics in determining the abiotic environments (biotopes) in which aquatic communities live. Particularly, in low-order river systems, different channel form features shape the biological community that can be hosted in a certain biotope. For this reason, the link between morphology and discharge is important when evaluating possible impacts of flow reduction on aquatic organisms. To represent the relationship between hydraulics and channel morphology quantitatively, a hydraulic diversity concept has been adopted. Studies from the literature have revealed that, in a regulated river, a decrease of the environmental variability including hydraulic diversity quite often resulted in a downstream decrease of the macro-invertebrate diversity, which can consequently affect fish biomass. These considerations create the ground for a hydraulic diversity-discharge–based in-stream flow method with the aim to promote high community diversity in a low-order regulated stream. A statistic ordination technique (correspondence analysis) applied to 370 hydraulic sections helped to identify four main morphological units (pools, deep pools, and slow and fast riffles) in terms of hydraulic diversity. In each morphological unit, the hydraulic diversity-discharge relationship was investigated and modeled by means of best-fit regression curves. Combining the hydraulic diversity-discharge curves from different morphological units (pools and riffles), a simplified model of the stream [pool quality index (PQI)] was obtained. This model has been applied to make recommendations for the minimum flow requirements in six low-order river sites. PQI recommendations were consistent with hydrology and other hydrology-based in-stream flow methodologies. Finally, a multiple regression model indicated that in 12 low-order stream sites a good deal of the variability of macro-invertebrate diversity is explained by the availability of hydraulic environments modeled by means of PQI curves. In conclusion, given the encouraging cues about the ecological meaning of PQI and the possibility to overcome difficulties typically encountered by other methods in the low-order river modeling, PQI can be considered a valid alternative for assessing the in-stream flow needs of low-order streams.     

基于回油调速的液压系统动态特性研究

回路调速系统是液压系统不可缺少的一部分,为了更好地了解系统性能,需对其进行动态特性分析,通常是采用传递函数法建立系统数学模型,虽然这种方法简单,但是效果不佳。文中采用功率键合图和传递函数混合建模法建立系统数学模型,利用Matlab软件仿真并分析了系统性能,对研究系统的性能和设计改进具有积极的作用。     

Reservoir Bank Deformation Modeling: Application to Grangent Reservoir

Within inshore or fluvial environments, submerged fine matter mud banks are characterized by a high water content, a great spatial variability, and a strong deformability. The study of their instabilities induced by the variation of hydraulic stress requires a coupled modeling of sliding, erosion, and deposition mechanisms. In order to predict the impact of dam reservoir emptying on the stability of immersed upstream slopes, the method of approach to the problem proposed here combines theoretical developments, numerical modeling, site observations, and measurements. First, the theoretically achieved sliding criterion is compared with unstable mud height measurements. For more accuracy in the representation of the natural events, the sliding criterion is then integrated within a numerical code which couples the computation of hydrodynamic conditions, the erosion, and deposition of mud and the banks sliding. Finally, the results of the combination of all these mechanisms are compared with the variations in the bathymetric profiles obtained on the experimental site.     

Hydrodynamic Performance of Wave-Driven Artificial Upwelling Device

Artificial upwelling and mixing is a new technology for enhancing open ocean mariculture using nutrient-rich deep ocean water. A wave-driven artificial upwelling device was developed based on mathematical modeling and hydraulic experiments. Results of the numerical modeling are in good agreement with hydraulic experiments. The mathematical model was applied to simulate the operation of a prototype device in typical Hawaiian waves. The prototype device consists of a buoy with a water chamber 4.0 m in diameter, a flow-controlling valve, and a long tail pipe 300 m in length and 1.2 m in diameter. This device can produce an upwelling flow of 0.62 m3∕s in regular Hawaiian waves with a period of 12 s and a wave height of 1.9 m. Two analytical solutions to the simplified governing equations were also derived that provide a basis for the derivation of predictive equations, useful for preliminary engineering design and analysis.     

Hydraulic Efficiency of Continuous Transverse Grates for Paved Areas

The hydraulic behavior of several continuous transverse gully grates is studied. Their use is common in some urban or impervious areas (squares, airport pavements, parks, pedestrian areas, etc.) where isolated inlets turn out to be ineffective in collecting the whole runoff into the sewer system during a storm event. Normally, manufacturers of such structures provide information about the bearing capacity, but little concerning their hydraulic behavior. Some grates with various widths were tested at the Technical University of Catalonia hydraulic laboratory for different approach flows and a large set of longitudinal slopes. Experimental equations were obtained to relate hydraulic efficiency of these structures to some relevant flow parameters such as the Froude number and the hydraulic depth. The first equation achieved may be used as a first approach to design a surface drainage system considering a constant circulating flow, whereas the second expression does not depend on flow values and could be used in storm-water and wastewater software packages to design surface drainage systems and for dual drainage modeling.     

Modeling In-Sewer Deposit Erosion to Predict Sewer Flow Quality

High levels of suspended solids are typically observed during the initial part of storms. Field evidence suggests that these suspended solids derive from the erosion of in-sewer sediment beds accumulated during dry and previous wet weather periods. Suspended sediment transport rate models within existing sewer network modeling tools have utilized inappropriate transport rate relationships developed mainly in fluvial environments. A process model that can account for the erosion of fine-grained highly organic in-sewer sediment deposits has been formulated. Values of parameters describing the increase in deposit strength with depth are required. These values are obtained using a genetic algorithm based calibration routine that ensures model simulations of suspended sediment concentrations that correspond to field data collected in a discrete length of sewer in Paris under known hydraulic event conditions. These results demonstrate the applicability of this modeling approach in simulating the magnitude and temporal distribution of suspended in-sewer sediment eroded by time varying flow. Further work is developing techniques to enable the application of this type of model at the network level.