混合动力液压挖掘机节能液压系统仿真分析

根据液压挖掘机的工况和混合动力技术的特点,提出了适合混合动力液压挖掘机的节能液压系统。为了证明节能液压系统的可靠性,以22t液压挖掘机为对象,用MATLAB软件进行了仿真。仿真结果表明,与采用开式节流控制系统的混合动力液压挖掘机相比,采用闭式节能液压系统的混合动力液压挖掘机的平均功率能减小到一半以下。从而发动机装机功率和油耗得到明显的改善。     

Parameters Affecting Hydraulic Behavior of Aerated Lagoons

Tracer studies were performed at the full-scale St-Hermas aerated lagoon, Quebec, Canada, and a dynamically similar laboratory model to determine the effects of the water flow rate and aeration rate on hydraulic mixing. The tracer study E-curves were extrapolated to ensure conservation of the tracer mass within the system and in turn were analyzed using a two-celled compartmental model. The results of the compartmental model analysis demonstrate that the water flow and aeration rates both influence the percentage of dead zones and bypassing within the system, with the water flow rate being the dominant parameter. This study therefore concludes that hydraulic mixing of aerated lagoons is significantly affected by the water flow and aeration rates. The ability to demonstrate that these hydraulic parameters affect the mixing of aerated lagoons is attributed to the E-curve development and the compartmental model analysis used in this study.     

Optimization and Analysis of Advective Travel Times beneath Hydraulic Structures

Steady, 2D Darcian seepage in a homogeneous isotropic porous medium under an impervious structure is studied by the methods of complex analysis. The geometry of the structure is studied focusing on the travel time of a marked (neutral tracer) particle from the upper pool to the tailwater. In the Verigin problem, the angle of inclination of a sheetpile resulting in minimal time along the bounding streamline is π/2. If the maximum of the minimum of the travel time is searched between all streamlines originated in the upper pool, then the optimal angles are found to be 0.404π and 0.596π. The minimization of the total volume of fluid that arrives from the upper pool to the tailwater during a prescribed time span is also considered. For arbitrary geometry, structure optimization with respect to travel time is carried out explicitly for the bounding streamline with a constraint on the wetted perimeter of a depressed structure. The minimal-time shape is found to be the Voshinin semicircular structure, which is mathematically generated by a line vortex.     

Performance Assessment of Hydraulic Efficiency Indexes

The analysis of residence time distribution functions originating from tracer studies is one of the main tools for the assessment of hydraulic performance in water and wastewater treatment units. In order to simplify the analysis, hydraulic indexes extracted from these functions are normally used. In general, these indexes are divided into two categories: short circuit and mixing indicators. However, some indexes may be related to more than one physical phenomenon (i.e., short circuit, mixing, recirculation, dead zones), leading to erroneous interpretation. In this work their capability to evaluate short-circuit and mixing levels in water and wastewater treatment units is assessed. Among the indexes analyzed, t10, which is the time necessary for 10% of the tracer to leave the unit, is recommended as a short-circuit indicator and the dispersion index (σ2) and the Morril index as mixing indicators, depending on the mixing level.     

Goodness-of-Fit Test for Modeling Tracer Breakthrough Curves in Wetlands

Wetland transport models generally either assume plug flow (with or without dispersion) or conceptualize the wetland as a series of continuously stirred tank reactors (CSTRs). To evaluate the CSTR approach, we present a goodness-of-fit test suitable for evaluating breakthrough curves from tracer experiments. The test, which makes use of confidence intervals associated with the multivariate normal distribution, can be used to test the fit of the breakthrough curve model, but requires sampling across a transect rather than from a single point. To test the CSTR assumption, we conducted a pair of two-dimensional tracer experiments within a 9.9?ha wetland constructed to receive effluent from a wastewater treatment plant in San Jacinto, Calif. The wetland operates with five parabolic inlets and a single large parabolic outlet to encourage lateral uniformity. In both experiments tritium oxide (HTO) was used as the tracer. Rhodamine WT dye was also included in the second experiment. Tracer samples were collected along transects installed perpendicular to the direction of flow. Analysis of the results indicates satisfactory lateral mixing and no significant short-circuiting. Rhodamine WT dye performed similarly to HTO when detectable but was too dilute to be observed at the outlet. When tracer movement was modeled as a series of continuously stirred reaction vessels, the parameter associated with the integer number of vessels increased from 2 at the first transect to 8 at the outlet. At each transect, the model was checked with a new goodness-of-fit test. At the α = 0.05 confidence level, all fitted models were rejected, suggesting that while the CSTR assumption may usefully approximate transport processes, it is not statistically valid for this wetland.     

钢管水压试验方法剖析

介绍了钢管进行水压试验的目的，剖析了水压试验现状和存在的问题，提出钢管材质检验的发展方向－无损检验技术的特点。     

Hydraulic Performance Index of a Sewer Network

An objective methodology is proposed for evaluating the hydraulic performance for possible rehabilitation of sewer systems. It involves assigning a hydraulic performance index to each pipe section. This hydraulic index reflects both the local surcharge in a pipe and the surcharge induced at upstream sections of the same branch in a sewer network. The hydraulic index also takes into account the vulnerability and the retention capacity of each pipe section. This index may be used directly to establish the rehabilitation priority of different sections to maximize hydraulic performance for the entire network. This methodology was successfully applied to the sewer system of the city of Laval in Canada. The results show how pipe dimensions and locations have the effect of surcharging or relieving a pipe network and how the hydraulic performance index adequately rates the contributions of sewer network components.     

SGXP—400液压泥炮的应用及其性能分析

通过本钢５＃高炉液压泥炮的技术改造实践，阐述了斜底座式液压泥炮在大型高炉上的应用情况，并且进一步对ＳＧＸＰ—４００液压泥炮的某些性能特点及其液压系统进行了分析。     

冶金液压缸常见故障分析及排除

通过对液压缸故障实例分析,对液压缸的常见故障特征进行分析,就其原因寻找对策,以避免事故的再发生。     

16—50液压旋回破碎机液压,润滑站国产化

介绍国产化液压破碎机液压、润滑站的工作原理， 并与进口设备进行技术比较，经使用验证达到了原设备的技术要求     

泥炮机回转油缸爬行现象的仿真与分析

介绍了泥炮机的主要结构和工作原理,分析现有回转回路的液压原理,提出用于液压仿真的简化回路,并利用AMEsim软件建立了简化回路的模型。对回转油缸、液控单向阀和电液换向阀的运动特性进行仿真分析,得到回转油缸爬行故障的原因。最后提出采用外控外排型电液换向阀和增加独立先导油源的改进方案,并再次利用仿真软件建立改进回路的模型,通过仿真分析验证改进回路的可行性,为进一步的改造实践提供了依据。     

液压油氧化的分析及延缓氧化的方法

阐述了液压油氧化的原因、危害、简易检测方法、控制措施及实际取得的效果。     

热轧平整线液压系统浅析

因原热轧平整线存在很多缺陷,不能发挥平整功能,建设了新平整线。对新平整线液压伺服系统控制原理、系统构成、功能、具有的工作模式以及辅助液压系统回路特点进行了详细分析;分析了系统运行中出现问题的原因,对提出的改进措施和实施效果进行了论述。     

Sensitivity Analysis for Hydraulic Models

Sensitivity analysis is well recognized as being an important aspect of the responsible use of hydraulic models. This paper reviews a range of methods for sensitivity analysis. Two applications, one to a simple pipe bend example and the second to an advanced Shallow Water Equation solver, illustrate the deficiencies of standardized regression coefficients in the context of functionally nonlinear models. Derivatives and other local methods of sensitivity analysis are shown to give an incomplete picture of model response over the range of variability in the model inputs. The use of global variance-based sensitivity analysis is shown to be more general in its applicability and in its capacity to reflect nonlinear processes and the effects of interactions among variables.     

高炉液压泥炮故障分析与对策

液压炮是维系高炉生产的重要设备 ,对济南钢铁集团总公司第一炼铁厂液压炮不同故障情况进行分析 ,并制定相应故障解决对策 ,从而有效地保证了液压炮稳定运行 ,保证了高炉的正常生产。     

冶金设备液压系统故障分析

液压系统在冶金设备上的应用日益广泛,液压系统的日常维护特别重要。通过对冶金设备液压系统故障的初步分析,提出了在日常维护过程中确保液压系统可靠运行的一些注意事项,对设备的维护管理具有一定的指导作用。     

Linear Solution for Hydraulic Analysis of Tapered Microirrigation Laterals

A simplified analytical solution that takes into account the effect of the emitter discharge exponent on the hydraulic computations of tapered microirrigation laterals, is presented. The hydraulic analysis is evaluated based on the spatially variable discharge function approach. A simple power equation was used to express distribution of the variable outflow delivered from the each emitter along the lateral. An analytical solution is developed for the case of a linear relationship between the emitter discharge and pressure head, namely, the emitter discharge exponent equals to unique, y = 1.0. In this procedure, the analytical derivations can be applied for uphill, downhill, and zero slope conditions. Results are comparable to those obtained from the literature.     

液压泵气蚀等故障的分析与整改

高速线材推钢式加热炉采用的液压泵存在气蚀损坏等故障,制约了生产,并造成成本增加,经改造泵气蚀等故障得以解决,并降低了电耗及备件成本。     

钢卷升降运输小车液压系统故障分析

钢卷升降运输小车广泛用于轧钢工业生产线,在使用过程中其液压系统经常出现故障,由于系统中各液压元件极易受到油液的影响,当污染严重时,油中的杂质会造成阀件损坯,阀芯卡滞、卡死,阻尼孔、节流口堵塞,从而使系统发生故障,文章对几种典型故障的原因进行了分析,并提出相应的处理方法。     

GWT58型液力偶合器工作原理及振动故障分析

介绍山西铝厂二期熟料窑窑前鼓风机配套的GWT58型速液力偶合器之工作原理，分析振动产生的原因，提出处理方法。