Hydraulic Mode Research Articles

Analysis of Construction Machinery Hydraulic Control System

This article analyses the use requirement of construction machinery, introduce the main features of typical construction machinery hydraulic system, derived power control modes of hydraulic system form hydraulic power form, compares the advantages and disadvantages of each power control mode, gives the optimization solutions, at last, sum up the full text of the construction machinery hydraulic power and control modes and prospect of the hydraulic system to precision control.

Antilock Braking System Slip Control Modeling Revisited

The introduction of anti-lock braking system (ABS) has been regarded as one of the solutions for braking performance issues due to its notable advantages. The subject had been extensively being studied by researchers until today, to improve the performance of the todays vehicles particularly on the brake system. In this paper, a basic modeling of an ABS braking system via slip control has been introduced on a quarter car model with a conventional hydraulic braking mode. Results of three fundamental controller designs used to evaluate the braking performance of the modeled ABS systems are also been presented. This revisited modeling guide, could be a starting point for new researchers to comprehend the basic braking system behavior before going into more complex braking systems studies.

Investigation of the Lox/Alcohol Propulsion System

This work describes the design of a liquid propellant rocket engine using non-toxic, low-cost propellants, for a second generation space transportation system. The primary goals of this effort were to identify the most attractive fuel and system design approach for sizing a workhorse engine and to determine technology advancements that are needed to provide subsequent system development. The emphasis of the analysis was directed toward propellant perfomance and engine characterization. On the basis of operational and cost criteria, ethanol was determined to be the best fuel candidate. Because of the high heat flux conditions at high chamber pressures, regenerative cooling was chosen as the preferred method of wall protection, leaving film cooling as a supplementary chamber cooling method. A finite element analysis was carried out to evaluate thrust chamber reliability on steady working operation and hydraulic test mode. The study contributed to establish a better understanding of propellant potentialities and to investigate the best means of utilizing these capabilities in typical engine designs.

Hydraulic System Design and Simulation of High-Speed Railway Dynamic Test System Excitation Device

The existing hydraulic excitation mode of valve controlled cylinder or pump controlled motor used in the excitation device of high-speed railway dynamic test system is difficult to meet the requirements of high exciting frequency, high exciting force and high amplitude. To solve these problems, the paper puts forward a bicyclic surface hydraulic cylinder, and designs the corresponding electro-hydraulic servo excitation system. According to the test system parameters，it establishes the mathematical model of the hydraulic system. It uses Matlab/Simulink to carry out theoretical analysis and digital simulation and uses PID Tuner to adjust the PID controller parameters. The simulation results show that the hydraulic excitation system designed meets the performance requirements of the high-speed railway dynamic test system excitation device.

Study on Eliminating Three Nitrogen of Recycling Aquaculture Using the New-Style Incorporated Aquarium

Aimed at the current problems of capacious of hydrotreater, susceptible to plugging by microbe and the accumulation of ammonia or nitrite nitrogen in aquaculture, the aquarium (contain with the water treatment processor) using physical filtration + biodegradation + activated carbon adsorption complex process was devised to treat aquaculture for recycle. Under different working conditions, the effects of water temperature, hydraulic retention time (HRT), air flow and aeration mode on removal efficiency of ammonia, nitrite nitrogen and nitrate nitrogen (three nitrogen) in aquaculture. The test results showed that sludge yielding in the hydrotreater was low and hydrotreater was insusceptible to be plug. In addition, under the conditions of water temperature 25°C, air flow 1.5L/min,HRT 1.5h and intermittent aeration (aerating once every 1h), the removal rate of ammonia nitrogen , nitrate nitrogen and nitrite nitrogen was over 97.5% ,96% and 98.7% respectively, it means the three nitrogen was not detected. Therefore, the incorporated aquarium could permanently preserved favorable living environment for fish and could provide technological security for three nitrogen remove of fish farm water and for intensifying water recycle.

Application of membranes to treat wastewater for its recycling and reuse: new considerations to reduce fouling and increase recovery up to 99 percent

The RO process is very attractive for providing high product quality through the removal of a number of contaminants like oil, detergents, organics, nitrates, ammonia, phosphates etc. However the main disadvantages of the modern RO techniques are connected with membrane fouling, concentrate flow and pretreatment that increase operational costs, complicate design and create problems of brine utilization. Often pretreatment costs even exceed reverse osmosis facilities costs. Now a number of successful attempts were undertaken to modify spiral wound membrane channels to limit fouling and scaling potential. As presented in a number of publications, elimination of the spacer mesh from the feed channels eliminates dead regions that provide scaling and fouling conditions whilst also reducing the risk of particle “trapping” and associated dramatic pressure increase. Introduction of a new “open channel” configuration offers a new perspectives to escape fouling and development of novel techniques to treat water with high fouling potential (high suspended matter, organics and supersaturated solutions). This novel concept of spiral wound module with an “open channel” design is developed, field-tested and introduced into practice. Fouling control is achieved due to the elimination of spacer and the implementation of an optimum hydraulic mode providing sufficient cross flow velocities, flushings and cleanings. The main principles of high recoveries, low maintenance and zero discharge are ensured by concentration of brine through re-circulation by 50−100 times by volume. Several examples of water treatment flow diagrams are presented to demonstrate of zero concentrate flow discharge. Coagulated suspended matter after membrane flushes is collected, sedimented and finally dewatered. The concentrated solution containing salts and impurities together with the wet sludge constitutes no more than 1 percent of initial water in part due to high supersaturation values due to the strong stability of calcium carbonate solutions.

A New Hydraulic Excitation Mode with Liquid-Filled Pipe

The current vibration modes, whether inertial vibration or hydraulic vibration, have some problems such as large power consumption and low energy utilization rate. A new low energy hydraulic excitation mode is presented. This mode takes the high-pressured pipe as the new excitation source. Periodic pressure pulsation generated by wave exciter makes the pipe vibrating. The vibration mode of pipe with fluid-structure interaction is established and solved with numerical method. The modal analysis and the simulation of the vibration have been carried out. An experimental platform is built to verify that the new hydraulic vibration can be exploited.

Experimental and dimensional characterization of a prototype piston-cylinder unit and validation using finite element analysis (FEA)

A prototype piston-cylinder unit, covering a pressure range of 0.5–35 MPa in the hydraulic mode, and its assembly was designed and manufactured. The effective area and the elastic distortion coefficient (lambda) of the piston-cylinder unit was determined both experimentally using cross-floating method and dimensionally and validated using finite element analysis. Pressure distributions and gap profiles along the clearance between piston and cylinder were determined using elastic distortions of piston and cylinder. In this study, a short summary for the design and the manufacturing processes of the device was explained. Results presented a good agreement between experimental and analytical value of the effective area as an order of 8 ppm difference and the 3% on the lambda.

Circulatory assistance in small infants and neonates with a hydraulically driven system: a viable option?

We have developed a new drive system for a cardiac assist system for use with newborns and infants. This study reports results of animal experiments in which this system was tested using a commercially available 25-ml ventricle. A major property of the device is its hydraulic mode, which allows not only for the conventional full-empty mode (chamber completely filled in diastole) but also for the filled-empty mode, in which the chamber is completely emptied in systole but only partially filled in systole; this mode gives full flexibility to adjust the pump frequency for any given pump flow rate. The assist device was applied in eight pigs (weight 9-14 kg) for left ventricular assistance during normal and impaired cardiac function (pacing-induced cardiac shock, mean arterial blood pressure less than 40 mmHg). Both, full-empty and filled-empty mode during normal cardiac function led to significantly decreased pulmonary capillary wedge pressure, suggesting load reduction of the right ventricle. In impaired cardiac function, circulatory assistance increased the diminished cardiac output and systolic arterial blood pressure, although only the latter was statistically significant. Neither arterial lactate concentration nor oxygen uptake was reduced during circulatory assistance for normal and impaired cardiac function. These results suggest that the cardiac ventricular assist device can be used as an effective circulatory assist device and that the function of the newly introduced filled-empty mode, which allows for a high degree of functional flexibility, is not inferior to that of the classical, but less flexible, full-empty mode.

A mineração de areia e os impactos ambientais na bacia do rio São João, RJ

Over the years, the Sao Joao River basin in southeastern Rio de Janeiro State – Brazil, underwent several anthropic interventions. During the 1950s and 1980s, the courses of this river and some of its tributaries were repeatedly straightened. Such actions intensified their flow-rates, increasing sand transportation and deposition, and sand- mining activities flourished. The sand exploitation, despite clearing silt and sediments from river channels, was undertaken without previous studies and monitoring which generated locational conflicts, and originated the assessment of the environmental impacts arising out of mining activities. The main purpose of this paper is to assess the effects of sand-mining on the Sao Joao River dynamics, while bearing in mind other types of land use and occupancy. In cross-sections of the river, studied at local ports, ample amounts of sediment were noted, with rapid replenishment in the mining areas. An analysis of the land use and occupancy maps of this river basin for three separate periods (1984, 1994 and 2000), allowed the identification of some of the sediment sources. The expansion of the devastated areas due to intensive rural use, probably gave its contribution speeding up the laminar soil erosion, and the result was an increase of the sediment burden in the river. Our conclusion is that the environmental quality of the Sao Joao River basin is more seriously endangered due to the sedimentary imbalance caused by the riverbed straightening projects and intensive land use than the sand-mining activities that may be assessed as producing a secondary environmental impact. In fact, sand-mining might even be carried out without adverse environmental impacts, if the natural conditions of the hydraulic mode of the fluvial system are kept, which particularly for the Sao Joao River are already jeopardized.

DEVELOPMENT OF A COMPUTER-CONTROLLED, HYDRAULIC, POWER TAKE-OFF (PTO) SYSTEM

Nearly all tractor PTO arrangements used today consist of a rotating mechanical shaft with two or more universaljoints. This arrangement continues to be an entanglement hazard. By driving the attachment with fluid power, this hazardcould be eliminated. This project included the design, development, and testing of an experimental tractor based on a JohnDeere 4040. The entire power train was treated as a single computer-controlled system where both the PTO output and thewheels were driven by fluid power. To support direct laboratory and in-field comparison of hydraulic and mechanicalscenarios, the original transmissions were left intact and functional. Results showed that at low power demand, the hydraulicsystem was more efficient than the mechanical equivalent; however, the mechanical version was more efficient over most ofthe load range and was capable of higher power output. The use of computer control helped to minimize fuel consumptionby matching engine speed to loading conditions while maintaining operating speeds by varying hydraulic pump displacement.The hydraulic PTO system for the JD 4040 has the potential to match or increase fuel efficiency compared to its mechanicalcounterpart for loads up to about 40% of rated mechanical PTO output. Maximum power output in the hydraulic mode hasthe potential to be 75% of that achieved by the mechanical equivalent.

Method of electrodialysis stack testing with the feed solution concentration regulation

A technique to test electrodialysis (ED) stacks designed to desalt dilute solutions is developed. The technique permits obtaining reproducible data on laboratory and medium-scale units useful for predicting mass transfer characteristics of large ED stacks. Quasi-steady state of desalination process is the main condition to obtain such data. This state can be attained by applying recycling hydraulic modes and special devices to maintain constant pH, or pH and concentration of the feed solution. To obtain data for scaling, it is necessary to apply a fixed voltage on the stack and to use a constant flow rate of the feed solution during the experiment, the feed solution concentration may vary with the time. Specifications of the stacks studied, rational hydraulic and electrical modes of testing are considered.

Responses of the planktonic diatom Asterionella formosa Hassall to abiotic environmental factors in a reservoir complex (south-eastern France)

The River Durance and its main tributary, the Verdon, are both highly regulated rivers flowing in south-eastern France. The course of both rivers is interrupted by a series of reservoirs with quite different geographical, morphometric, climatic, hydrodynamic and chemical characteristics. The planktonic diatom Asterionella formosa Hassall, which has undesirable cyclic effects from the water management point of view, was studied in this complex of reservoirs located in the Mediterranean region. The results indicate that only the monomictic calcareous reservoirs show a bimodal pattern of Asterionella formosa abundance. The population dynamics of this algal species was found to depend on both the morphometric features and the hydraulic mode of management (retention time) used at each reservoir, as well as on the physical (temperature, suspended matter) and chemical (nitrogen, silica, calcium) characteristics of the water.

`Crack–seal', slip: a new fault valve mechanism?

This paper presents a new model of fault development in carbonate rocks involving a crack–seal–slip sequence. The structures of sheared calcite veins from the Les Matelles outcrop, Languedoc (S. France), and the observations used to construct this new model which integrates aspects of `crack–seal' evolution of calcite-filled veins with concepts of fault valve behaviour are described. In our model, hydraulic mode I reopening of an oblique pre-existing vein in an overall strike-slip stress regime is accompanied by precipitation of calcite, but significant fault slip cannot occur initially despite this obliquity because the ends of the pre-existing structure limit further reopening propagation beyond the tips. The rate of aligned calcite precipitation keeps pace with the rate of dilation of the structure, so that calcite cement essentially seals the system. Stress concentrations at the tips are allowed to rise with reopening until failure of the tip zone results in branch crack formation, triggering both slip along the vein and hydraulic pressure drop. This is followed by sealing within the branch cracks. Such a crack–seal–slip cycle may be repeated several times, as evidenced by fault-perpendicular calcite vein growth interlayered with calc-mylonite lamellae within these structures. Later cycles will become less pronounced because strength recovery of the sealed branch cracks does not regain the initial strength of the intact rock. This model could apply at various scales, and could be a mechanism for triggering earthquakes.

Choosing the electrodialyzer design and hydraulic modes for demineralization of dilute solutions

The purpose of the work presented is the investigation of electrodialysis apparatuses of two types differing by demineralization chambers construction only. These are pilot apparatuses based on Russian membranes: cation exchange MK-40 and anion exchange MA-40.

The Propagation of Slow Wave Potentials in Pea Epicotyls

Slow wave potentials are considered to be electric long-distance signals specific for plants, although there are conflicting ideas about a chemical, electrical, or hydraulic mode of propagation. These ideas were tested by comparing the propagation of hydraulic and electric signals in epicotyls of pea (Pisum sativum L). A hydraulic signal in the form of a defined step increase in xylem pressure (Px) was applied to the root of intact seedlings and propagated nearly instantly through the epicotyl axis while its amplitude decreased with distance from the pressure chamber. This decremental propagation was caused by a leaky xylem and created an axial Px gradient in the epicotyl. Simultaneously along the epicotyl surface, depolarizations appeared with lag times that increased acropetally with distance from the pressure chamber from 5 s to 3 min. When measured at a constant distance, the lag times increased as the size of the applied pressure steps decreased. We conclude that the Px gradient in the epicotyl caused local depolarizations with acropetally increasing lag times, which have the appearance of an electric signal propagating with a rate of 20 to 30 mm min-1. This static description of the slow wave potentials challenges its traditional classification as a propagating electric signal.