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Добірка наукової літератури з теми "Hydraulics proportional"

Автор: Grafiati

Опубліковано: 30 травня 2022

Оновлено: 31 травня 2022

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Статті в журналах з теми "Hydraulics proportional"

Ding, Wen Si, Jian Yuan Liao, and Lin Yan Yuan. "Design and Simulation Analysis of the Multi-Stage Linear Synchronous Expanding and Contracting Hydraulic Cylinder." Applied Mechanics and Materials 779 (July 2015): 35–41. http://dx.doi.org/10.4028/www.scientific.net/amm.779.35.

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Анотація:

A double-action three-stage synchronous expanding and contracting hydraulic cylinder has been designed based on the principle of synchronous expanding and contracting hydraulics cylinder. The Principle of linear synchronous expanding and contracting hydraulics cylinder and the main points of design have been discussed. Modeling and simulation are conducted in AMESim system and the result shows that the multi-stage cylinder can expand and contract synchronously and smoothly. As long as the effective area is proportional, the multi-stage cylinder can move linearly.

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Suzuki, Kenji, Sho Akazawa, and Yohichi Nakao. "Development of Cam-Drive Type Proportional Valve for Water Hydraulics." International Journal of Automation Technology 6, no. 4 (July 5, 2012): 450–56. http://dx.doi.org/10.20965/ijat.2012.p0450.

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This paper describes the development of water hydraulic proportional valves. These valves are spooltype and the spool is driven by a positive cam mechanism with an appropriate motor, such as a stepping motor or servo motor, depending on the application. The cam is placed precisely between two cam followers so that no gap is left between the cam and followers. Accordingly, no return spring is required. The rotational angle of the cam and the displacement of the spool are linear. Mathematical models of static characteristics of the valves are derived. Experimental results for the static characteristics are also shown: internal leakage and pressure gain against spool displacement, flow rate characteristics with no load, and flow rate against load pressure. Although the spool overlaps with sleeve, no dead band was observed in flow rate characteristics with no load because of leakage passing through the clearance around the spool. In addition, the nonlinearity of spool displacement against the rotational angle of the cam was below 0.2% and hysteresis was hardly observed. Feedback control of the displacement of water hydrostatic bearings is conducted as an application of the developed valve.

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Akdemir, Bayram. "Novel Intelligent and Sensorless Proportional Valve Control with Self-Learning Ability." Journal of Sensors 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/8141720.

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Анотація:

Linear control is widely used for any fluid or air flows in many automobile, robotics, and hydraulics applications. According to signal level, valve can be controlled linearly. But, for many valves, hydraulics or air is not easy to control proportionally because of flows dynamics. As a conventional solution, electronic driver has up and down limits. After manually settling up and down limits, control unit has proportional blind behavior between two points. This study offers a novel valve control method merging pulse width and amplitude modulation in the same structure. Proposed method uses low voltage AC signal to understand the valve position and uses pulse width modulation for power transfer to coil. DC level leads to controlling the valve and AC signal gives feedback related to core moving. Any amplitude demodulator gives core position as voltage. Control unit makes reconstruction using start and end points to obtain linearization at zero control signal and maximum control signal matched to minimum demodulated amplitude level. Proposed method includes self-learning abilities to keep controlling in hard environmental conditions such as dust, temperature, and corrosion. Thus, self-learning helps to provide precision control for hard conditions.

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AKAZAWA, Sho, Kenji SUZUKI, and Yohichi NAKAO. "G110022 Dynamic characteristics of a cam-drive type proportional valve for water hydraulics." Proceedings of Mechanical Engineering Congress, Japan 2011 (2011): _G110022–1—_G110022–4. http://dx.doi.org/10.1299/jsmemecj.2011._g110022-1.

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Zhang, Zeng Meng, and Yong Jun Gong. "Design and Simulation on Multi-Digit Numerical Control Valve in Water Hydraulics." Advanced Materials Research 422 (December 2011): 257–61. http://dx.doi.org/10.4028/www.scientific.net/amr.422.257.

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Анотація:

Due to the problems about Lubrication and sealing in water hydraulics, the poor performance, large leakage, extreme requirements of processing, high cost and poor anti-pollution properties exist in water hydraulic servo or proportional valves of spool structure and analogue control. A better seal is provided by the structure of the poppet valve comparing to the spool valve, however, poorer linearity and control accuracy accompanying inevitably. Aiming at improving the control performance of poppet valve, the design of the multi-digit numerical control valve is analyzed in this paper. The novel design using ball seat valves for digital bits is proposed to ensure enough seal ability and lower the cost. The simulation model of the multi-digit numerical control valve is built in AMESim software and the results show high linearity in flow control. However, large overshoot and oscillation encounter during the switching of the digits. Especially the switching process of the high digital bits requires to be regulated to reduce the large overshooting. The adjustment of the spring in the sensitive chamber of the bit valve can decrease the overshoot and improve the stability. These above contribute to the improvement of the control performance of water hydraulic control valves and applications of water hydraulics in the industry.

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Mohammed, Jamal AK, Walaa M. Hashim, and Bahaa S. Beram. "Performance Improvement of a Conventional Hydraulic Elevator by Using Electro-Hydraulic Servo Mechanism." Engineering and Technology Journal 38, no. 5A (May 25, 2020): 748–60. http://dx.doi.org/10.30684/etj.v38i5a.367.

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Анотація:

An electro-hydraulic elevator is a new type of enhanced elevators that are used in low-rise buildings that do not exceed more than three floors. In this paper, an electro-hydraulic servo system for controlling the speed of a hydraulic elevator prototype by using a proportional valve and PID controller was investigated theoretically and experimentally. A three floors elevator prototype model with 76cm height was built including hydraulics components and electrical components. The elevator system is fully automated using the Arduino UNO board based Data Acquisition (DAQ) system. LabVIEW software is used to control the hydraulic elevator system through L298 DC drive via the DAQ board. The best PID gains was obtained experimentally. The elevator system prototype could be emplimented for educational purposes; such as learning the undergraduate students in the Electromechanical Engineering Department in the University of Technology how to structuring the electro-hydraulic elevator as well as the appropriate control strategy.

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Osiecki, Leszek, Piotr Patrosz, Tomasz Zawistowski, Bettina Landvogt, Janusz Piechna, and Bartek Żyliński. "Compensation of Pressure Peaks in PWK-Type Hydraulic Pumps." Key Engineering Materials 490 (September 2011): 33–44. http://dx.doi.org/10.4028/www.scientific.net/kem.490.33.

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Анотація:

Hydraulic axial pumps equipped with cam-driven commutation unit (PWK pumps) proved their high efficiency up to 55 MPa and ability to work self-sucking, even at high speed. Displacement of PWK pump may easily be changed by moving its control cam. Full discharge from hydrostatic forces makes such control possible by direct action of a low-energy actuator like proportional electromagnet or stepping motor. That eliminates heavy and costly hydraulic servomechanism, necessary in other variable displacement machines. Such a control mechanism was positively evaluated in prototype tests in Department of Hydraulics and Pneumatics of Gdańsk University of Technology. The new commutation unit generates however harmful pressure peaks. The paper presents the compensation method for pressure peaks by use of the elastic compensation chamber. It shows also results of multidisciplinary FEA and CFD analysis necessary to properly design the compensation chamber.

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Zhang, Shuzhong, Tianyi Chen, and Fuquan Dai. "Adaptive Backstepping Sliding Mode Control for Direct Driven Hydraulics." Proceedings 64, no. 1 (November 20, 2020): 1. http://dx.doi.org/10.3390/iecat2020-08496.

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Анотація:

Due to the advantages of high energy efficiency and environmental friendliness, the electro-hydraulic actuator (EHA) plays a vital role in fluid power control. One variant of EHA, double pump direct driven hydraulics (DDH), is proposed, which consists of double fixed-displacement pumps, a servo motor, an asymmetric cylinder and auxiliary components. This paper proposes an adaptive backstepping sliding mode control (ABSMC) strategy for DDH to eliminate the adverse effect produced by parametric uncertainty, nonlinear characteristics and the uncertain external disturbance. Based on theoretical analysis, the nonlinear system model is built and transformed. Furthermore, by defining the sliding manifold and selecting a proper Lyapunov function, the nesting problems (of the designed variable and adaptive law) caused by uncertain coefficients are solved. Moreover, the adaptive backstepping control and the sliding mode control are combined to boost system robustness. At the same time, the controller parameter adaptive law is derived from Lyapunov analysis to guarantee the stability of the system. Simulations of the DDH are performed with the proposed control strategy and proportional–integral–differential (PID), respectively. The results show that the proposed control strategy can achieve better position tracking and stronger robustness under parameter changing compared with PID.

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AKAZAWA, Sho, Kenji SUZUKI, and Yohichi NAKAO. "1709 Study on improvement of dynamic characteristics of cam-drive type proportional valve for water hydraulics." Proceedings of Conference of Kanto Branch 2012.18 (2012): 21–22. http://dx.doi.org/10.1299/jsmekanto.2012.18.21.

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Brown, F. T., S. C. Tentarelli, and S. Ramachandran. "A Hydraulic Rotary Switched-Inertance Servo-Transformer." Journal of Dynamic Systems, Measurement, and Control 110, no. 2 (June 1, 1988): 144–50. http://dx.doi.org/10.1115/1.3152664.

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Switched-reactance hydraulics represents a radically novel approach to the control of fluid power, since the proportional metering of flow through adjustable orifices is eliminated, and the inertive properties of the fluid substituted. Potential advantages in bandwidth, linearity, and efficiency have been indicated. This paper presents the first steady-state theory and experiments with a rotary fluid switch, which accomplishes the needed pulse-width modulation at a desirably high frequency. Cavitation problems are observed, means of their partial solution are implemented, and means of a more complete solution are indicated.

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Дисертації з теми "Hydraulics proportional"

Fahlén, Daniel, and Ludvig Fri. "Modelling and Control of a Forklift’s Hydraulic Lowering Function." Thesis, Linköpings universitet, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-139247.

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Material handling and logistics are fundamental parts of today’s global societyand forklifts are a crucial part of the material handling process. Making these asefficient and reliable as possible are therefore of great interest. In this master thesis, an effort has been made to improve the control of the hydraulic lowering function of a specific forklift. Today the lowering function iscontrolled through an open-loop control scheme making the control performancesensitive to disturbances and system changes. One disturbance of special interestis the temperature of the hydraulic fluid. The goal of this thesis was therefore todesign a controller with improved robustness as well as improved performance. To solve this a model-based control design approach was used and a nonlineargrey-box model was derived, implemented and validated. The model parameterswere estimated using a nonlinear least-squares optimisation problem. The resulting model captures most of the system dynamics and the model fit is higher than 70% which was deemed good enough to use for control design. A PID controller was designed based on the estimated model and the controllerparameters were optimised. Furthermore, the controller was evaluated in simulations and implemented in a real forklift. The proposed controller was compared to the original controller for various scenarios. The results reveal improvedsteady state behaviour with enhanced temperature robustness compared to theoriginal controller.
Materialhantering och logistik är viktigt för att dagens globala samhälle ska fungera. En grundläggande del i materialhanteringsprocessen är gaffeltruckar, därför är det av intresse att göra gaffeltruckar så effektiva och pålitliga som möjligt. I det här examensarbetet har ett försök gjorts till att förbättra styrningen av den hydrauliska sänkningsfunktionen hos en specifik gaffeltruck. Dagens lösning använder sig av öppen styrning vilket gör reglerprestandan känslig för störningar och systemförändringar. En störning av extra intresse är temperaturen av hydraulvätskan. Målet med detta arbete var därför att designa en regulator med ökad robusthet och prestanda. För att lösa detta har en modellbaserad metod för regulatordesign använts där en olinjär gray-box modell härleddes, implementerades och validerades. Modellparametrarna skattades genom att ställa upp och lösa ett ickelinjärt minsta-kvadrat optimeringsproblem. Den resulterande modellen fångar det mesta av systemdynamiken och modellpassningen till uppmätt data var högre än 70\% vilket ansågs bra nog för att kunna använda modellen som en bas för regulatordesign. En PID regulator designades och regulatorparametrarna optimerades med hjälp av modellen. Regulatorn utvärderades i simuleringar och för att sedan implementeras den på en riktig gaffeltruck. Den föreslagna regulatorn jämfördes med den ursprungliga regulatorn i flera olika testfall. Resultaten visade ett bättre steady-state beteende och ökad robusthet mot temperaturförändringar för den designade regulatorn jämfört med den ursprungliga regulatorn.

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Скворчевський, Олександр Євгенович, та Христина Михайлівна Віленська. "Електрогідравлічні мехатронні модулі поступального руху: історія, сучасний стан, перспективи розвитку". Thesis, Харківський національний автомобільно-дорожній університет, 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/28258.

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Анотація:

Метою робота є аналіз існуючих електрогідравлічних мехатронних модулів поступального руху, виявлення основних напрямків їх розвитку та перспектив подальшого вдосконалення. В результаті прослідковано еволюцію таких систем. Запропоноване схемне рішення мехатронного модуля для проведення подальших науково-дослідних та проектно-конструкторських робіт в цьому напрямку.
The aim is to analyze existing electro-mechatronic modules translational motion, identifying the main areas of development and prospects for further improvement. The result followed the evolution of such systems. The proposed schematics mechatronic module for further research and design work in this direction.

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Bodin, Erik, and Henric Davidsson. "Model-Based Design of a Fork Control System in Very Narrow Aisle Forklifts." Thesis, Linköpings universitet, Reglerteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-138049.

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This thesis explains the model-based design of a fork control system in a turret head operated Very Narrow Aisle forklift in order to evaluate and push the limits of the current hardware architecture. The turret head movement consists of two separate motions, traversing and rotation, which both are hydraulically actuated. The plant is thoroughly modeled in the Mathworks softwares Simulink/Simscape to assist in the design of the control system. The control system is designed in Simulink/Stateflow and code-generated to be evaluated in the actual forklift. Optimal control theory is used to generate a minimum-jerk trajectory for auto-rotation, that is simultaneous traversing and rotation with the load kept in centre. The new control system is able to control the system within the positioning requirements of +/- 10 mm and +/- 9 mrad for traversing and rotation, respectively. It also shows good overall performance in terms of robustness since it has been tested and validated with different loads and on different versions of the forklift. However, the study also shows that the non-linearities of the system, especially in the hydraulic proportional valves, causes problems in a closed-loop control system. The work serves as a proof of concept for model-based development at the company since the development time of the new control system was significantly lower than for the original control system.

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Kontz, Matthew Edward. "Haptic Control of Hydraulic Machinery Using Proportional Valves." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19876.

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Supplying haptic or force feedback to operators using hydraulic machinery such as excavators has the potential to increase operator capabilities. Haptic, robotic, human-machine interfaces enable several enhancing features including coordinated motion control and programmable haptic feedback. Coordinated or resolved motion control supplies a more intuitive means of specifying the equipment's motion. Haptic feedback is used to relay meaningful information back to the user in the form of force signals about digging force acting on the bucket, programmable virtual constraints and system limitations imposed by the mechanism, maximum pressure or maximum flow. In order to make this technology economically viable, the benefits must offset the additional cost associated with implementation. One way to minimize this cost is to not use high-end hydraulic components. For smaller backhoes and mini-excavators this means that the hydraulic systems are comprised of a constant displacement pump and proportional direction control valves. Hydraulic and haptic control techniques suitable for backhoes/excavators are developed and tested on a small backhoe test-bed. A virtual backhoe simulator is created for controller design and human evaluation. Not only is the virtual simulator modeled after the test-bed, but the control algorithm used in the simulator is the same as the actual backhoe test-bed. Data from human subject tests are presented that evaluate the control strategies on both the real and virtual backhoe. The end goal of this project is to incorporate coordinated haptic control algorithms that work with low-cost systems and maximize the enhancement of operator capabilities.

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Hoferek, Martin. "Řízení proporcionálního hydraulického ventilu." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-316385.

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The thesis deals with design and implementation of proportional hydraulic valve, which will be integrated to hydraulic system of small hydro in Rájec - Jestřebí. This valve will be used to control one of the wicket gates of double Francis turbine. The thesis is processed for the company Mavel a.s., which is the owner of SH. The goal of this thesis is to create control of the valve according to the client's requirements, its implementation to the control system and commissioning.

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Vácha, Ondřej. "Testovaní charakteristiky proporcionální hydraulické kostky." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400453.

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Goal of this thesis is to verify functions of hydraulic manifolds from new supplier, measure characteristics of pressure loss relative to flow rate and for proportional blocks also characteristics of flow rate relative to control voltage at constant inlet pressure. Verification will be carried out with proportional manifolds and on/off manifolds with different failure functions.

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André, Simon. "Design and Optimization of Controllers for an Electro-Hydraulic System." Thesis, Linköpings universitet, Reglerteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-107620.

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Electro-Hydraulic (EH) systems are commonly used in the industry for applications that require high power-weight ratios and large driving forces. The EH system studied in this master thesis have recently been upgraded with new hardware components and as a part of this upgrade a new controller was requested. The system consists of a controller that computes a control signal for an electric motor. The motor drives a gear pump that generates a flow of hydraulic fluid. The flow is then directed to a cylinder. The movements of a piston in the cylinder is affected by the flow and the piston position can be measured. The measured piston position is then fed back to the controller and the control loop is complete. The system was previously controlled using a Proportional-Integral-Derivative (PID) controller and the purpose of this thesis is to compare the old controller with alternative control strategies suitable for this application. The evaluation of the controllers is based on both software and hardware simulations and results in a recommendation for final implementation of the best suited controller. The control strategies chosen for investigation are: a retuned PID controller, a PID controller with feed forward from reference, a PID based cascade controller, a Linear Quadratic (LQ) controller, and a Model Predictive Controller (MPC). To synthesize the controllers an approximate model of the system is formed and implemented in the software environment Matlab Simulink. The model is tuned to fit recorded data and provides a decent estimation of the actual system. The proposed control strategies are then simulated and evaluated in Simulink with the model posing as the real system. These simulations resulted in the elimination of the cascade controller as a possible candidate since it proved unstable for large steps in the reference signal. The remaining four controllers were all selected for simulation on the real hardware system. Unfortunately the MPC was never successfully implemented on the hardware due to some unknown compatibility error and hence eliminated as a possible candidate. The three remaining control strategies, PID, PID with feed forward from reference and the LQ controller, were all successfully implemented and simulated on hardware. The results from the hardware simulations compared to simulations made with the old controller, as well as the results from the software simulations, were then evaluated. Depending on the purpose one of two control strategies is recommended for this application. The LQ controller achieved the best overall performance and is presented as the control strategy best suited for this application.

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Vintr, Pavel. "Lineární jednotka s hydraulickým pohonem pro robot s paralelní kinematickou strukturou." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230468.

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This Master thesis deals with the design of linear unit with hydraulic actuator for the robot with parallel kinematic structure. One of the objectives is to get an overview of the differences related to characteristics of design and construction between serial and parallel kinematic structure (PKS) of the industrial robots, as a new type of technical objects in robotics. In addition the aim is to create an original structural design of linear unit, as the basic constructional assembly and operational node of robot with PKS, according to the specified input values, such as power, pressure, speed and stroke, important for the design of linear hydraulic actuator.

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Huang, Szu-Wei, and 黃思維. "Hydraulic Characteristics of Detention Dam with Linear Proportional." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/11039002092875420986.

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Анотація:

碩士
國立中興大學
土木工程學系
92
Abstract A detention pond is practically set to reduce the peak flow, delay the peak time and alleviate the amount of excess flood due to the upstream development. Linear proportional weirs are used in this study. The outlet has a rectangular base over which a fitting shape is designed. This special arrangement allows a rapid discharge prior to the arrival of peak flow thus leaves a greater capacity to accommodate the income flood. A numerical hydrological routing model is proposed to investigate the characteristics of flood detention with six linear proportional weirs considering six triangular and five trapezoidal inflow hydrographs. The detention pond experiments are also carried out to verify the suitability of proposed numerical model. The results of the study are outlined as follow: 1. Based on the hydrology continuity equation (3-15) and linear proportional weir discharge equation (3-17), we can calculate the governing equations (3-29) to (3~31) of triangular and trapezoidal inflow hydrographs. By using the Runge-Kutta numerical method together with the verified results from the detention pond experiment, the numerical model can provide a good way for flow prediction. 2. In this research, the regression formulas for peak reduction κ of linear proportional weir in equations (5-2), (5-3) with triangular hydrographs and in equations (5-6), (5-7) representing trapezoidal hydrographs are obtained. By using these regression formulas, we can ratiocinate the value of κ is less when the bottom width b or height a of rectangular outlet is larger, while the value of κ becomes larger when the ratio of shape a/b is greater. As for the dimensionless peak lag time Ts , it increases when the characteristic parameter of the triangular or trapezoidal inflow hydrograph increases. In addition, Ts is larger than zero when the value of κ approaches zero. It means that the peak time can have a lag although peak discharge is not reduced. Equations (5-4) and (5-8) are the regression formulas of Ts with κ and characteristic parameters 、 for references. 3. With comparison of the differences of storage volume between triangular and trapezoidal inflow hydrographs, it can be seen that the detention pond of trapezoidal hydrograph needs larger dimensionless storage volume than that of the triangular hydrograph when peak outflow is the same. Figures 5-20 and 5-33 show the storage volume for the linear proportion weir is less than that of the rectangular spillway. It is implied that the outlet for the linear proportional weir has a better detention effect. Also, the regression formulas for with κ of triangular and trapezoidal inflow hydrographs in equations (5-5) and (5-9) are provided for references.

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XIE, YI-ZHE, and 謝佾哲. "CFD Simulation and Experimental Investigation of Hydraulic Proportional Damper." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/f5gm3e.

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Анотація:

碩士
國立雲林科技大學
機械工程系
107
In this paper, the CFD simulation of the hydraulic proportional suspension damper is used to analyze various fluid phenomena such as fluid pressure, flow, flow line and shock absorber damping force inside the electronically controlled proportional valve. Firstly, it is practicall impossible to get the corresponding value of the correct opening of the main and pilot stage inside the electronically controlled proportional valve. This parameter is an important boundary condition when executed CFD simulation analysis. On the other hand, it is also clear that the CFD simulation cannot be executed if the boundary conditions for the simulation are unknown. To solve this problem, the force equilibrium equation for the main stage is derived. From this equation, the corresponding value of the correct opening of the main and pilot stage can be determined by trial-and-error approach. This study also focuses on the three critical dimensions inside the electronically controlled proportional valve, and explore the influence of the dimension changes on the damping force of the shock absorber and the evaluation of the soft and hard design of the shock absorber. Finally, this study tests the performance of the shock absorber through the shock absorber test bench. The relationship between the damping force and velocity of the shock absorber obtained by the experimental results is compared with the results of CFD simulation analysis. After comparison, although the experimental and CFD analysis results are slightly deviated, but the curilinear trend is very close. From this result, the reliability of the CFD simulation analysis method in this paper is verified. It is expected that the research results in this paper will make a concrete contribution to the research and development of domestic shock absorbers in the future.

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Книги з теми "Hydraulics proportional"

MacCurdy, Edward, ed. The Notebooks of Leonardo Da Vinci: Arranged, Rendered into English, and Introduced by Edward MacCurdy. Old Saybrook, CT,: Konecky & Konecky, 2003.

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Leonardo. Leonardo: Un hombre universal en los límites extremos de la mente y del arte. Madrid: Electa, 1999.

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1950-, Desmond Michael, Pedretti Carlo, Leonardo da Vinci 1452-1519, and Powerhouse Museum, eds. Leonardo da Vinci: The Codex Leicester--notebook of a genius. Sydney, N.S.W: Powerhouse, 2000.

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Carlo, Pedretti, Melani Margherita, and Basilique nationale du Sacré-Coeur (Belgium), eds. Leonardo da Vinci: The European genius : paintings and drawings : exhibition in the Basilica of Koekelberg, Brussels, in celebration of the 50th anniversary of the Treaty of Rome for the constitution of the European Community (1957-2007). Foligno (PG) [i.e. Perugia, Italy]: Cartei & Bianchi, 2007.

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Leonardo. Leonardo da Vinci: I manoscritti dell'Istituto di Francia. Edited by Govi Gilberto 1826-1889, Poli Capri Paola, and Istituto di Francia. Roma: H. van der Poel, 2000.

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Leonardo. Leonardo da Vinci: Attualità e mito = Leonardo da Vinci : aktualitás és mítosz. [S.l.]: Museo Ideale, 1991.

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K, Kustodieva T., Strinati Claudio M, Palazzo ducale (Venice Italy), Palazzo del Quirinale (Rome, Italy), and Gosudarstvennyĭ Ėrmitazh (Russia), eds. Leonardo: La Madonna Litta dall'Ermitage di San Pietroburgo. Roma: De Luca, 2003.

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Leonardo. Leonardo da Vinci: Engineer and architect. [Montreal]: Montreal Museum of Fine Arts, 1987.

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C, Marani Pietro, Fiorio Maria Teresa, and Castello sforzesco, eds. Leonardo: Dagli studi di proporzioni al Trattato della pittura. Milano: Electa, 2007.

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Leonardo. Leonardo da Vinci: Künstler, Erfinder, Wissenschaftler. Speyer: Historisches Museum der Pfalz, 1995.

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Частини книг з теми "Hydraulics proportional"

Inderelst, Martin, and Hubertus Murrenhoff. "Hydraulic Proportional and Servo Valves." In Encyclopedia of Lubricants and Lubrication, 881–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-22647-2_38.

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Wollschlaeger, Martin, Erik Unger, and Heiko Witte. "CANopen Device Profile for Hydraulic Proportional Valves." In Fieldbus Technology, 118–25. Vienna: Springer Vienna, 1999. http://dx.doi.org/10.1007/978-3-7091-6421-1_16.

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Luan, D. T., L. Q. Ngoc, and P. H. Hoang. "Dynamic Analysis of Hydraulic–Mechanical System Using Proportional Valve." In Proceedings of the International Conference on Advances in Computational Mechanics 2017, 991–1001. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7149-2_69.

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Owczarek, Piotr, Dominik Rybarczyk, and Arkadiusz Kubacki. "Dynamic Model and Simulation of Electro-Hydraulic Proportional Valve." In Automation 2017, 99–107. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-54042-9_9.

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Shen, Wei, and Junzheng Wang. "A Driving Method of the Electro Hydraulic Proportional Valve Based on Compensation Network." In Informatics in Control, Automation and Robotics, 199–204. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-25899-2_27.

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"Landscape Influences on Stream Habitats and Biological Assemblages." In Landscape Influences on Stream Habitats and Biological Assemblages, edited by Dana M. Infante, Michael J. Wiley, and Paul W. Seelbach. American Fisheries Society, 2006. http://dx.doi.org/10.47886/9781888569766.ch16.

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<em>Abstract.</em>—We investigated the effects of channel shape on the fish assemblages of 51 streams in Michigan’s Lower Peninsula. We considered three measures of stream channel shape: the low-flow hydraulic radius, channel incision, and a measure of channel fit (bank-full over lowflow stream width). Covariance structure analysis (CSA) was used to quantify relationships among fish assemblage properties, channel shape variables, and a number of other reach and catchment scale measures, including stream slope, catchment area, and the proportions of agriculture and coarse surficial geology in stream catchments. Our analyses showed that with increasing channel incision, total fish biomass decreased and that decreasing low flow hydraulic radius led to a reduction in the biomass of intolerant fishes. Our analyses emphasized the ways that catchment and reach scale measures affected fish assemblages through their effects on catchment hydrology, stream hydraulics, and stream channel shape. Catchment area was positively related to species richness and the average weight of fish; coarse geology was positively related to the biomass of the intolerant assemblage and to the average weight of intolerant fishes; and stream slope was negatively related to species richness and the average weight of individuals. Catchment agriculture had negative effects on the average weight of fish, yet species richness was found to increase with this measure, possibly due to the positive relationship between catchment agriculture and stream temperature. By investigating the effects of large scale factors on measures of channel shape and stream fishes with CSA, this study provides insights into the mechanisms by which the landscape influences stream fish assemblages.

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Azar, Ahmad Taher, Fernando E. Serrano, and Sundarapandian Vaidyanathan. "Proportional Integral Loop Shaping Control Design With Particle Swarm Optimization Tuning." In Advances in System Dynamics and Control, 24–57. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-4077-9.ch002.

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Backlash is one of several discontinuities found in different kinds of systems. It can be found in actuators of different types, such as mechanical and hydraulic, giving way to unwanted effects in the system behavior. Proportional integral (PI) loop shaping control design implementing a describing function to find the limit cycle oscillations and the appropriate control gain selection by particle swarm optimization is developed. Therefore, a frequency domain approach is implemented for the control of nonlinear system of any kind such as robotics, mechatronics, and other kind of mechanisms, electrical motors, etc. Finally, in order to corroborate the theoretical background explained in this chapter, the stabilization of a cart-pendulum system with the proposed control strategy is shown.

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Yang, Jiewei, Ruiying Bai, Jiwei Cai, Jixu Wu, and Weihua Liu. "Influence of mixture proportion on bleeding of concrete." In Progress in Civil, Architectural and Hydraulic Engineering IV, 1111–14. CRC Press, 2015. http://dx.doi.org/10.1201/b19383-228.

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Gray, William G., and Michael A. Celia. "Incorporation of Interfacial Areas in Models of Two-Phase Flow." In Vadose Zone Hydrology. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780195109900.003.0006.

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The mathematical study of flow in porous media is typically based on the 1856 empirical result of Henri Darcy. This result, known as Darcy’s law, states that the velocity of a single-phase flow through a porous medium is proportional to the hydraulic gradient. The publication of Darcy’s work has been referred to as “the birth of groundwater hydrology as a quantitative science” (Freeze and Cherry, 1979). Although Darcy’s original equation was found to be valid for slow, steady, one-dimensional, single-phase flow through a homogeneous and isotropic sand, it has been applied in the succeeding 140 years to complex transient flows that involve multiple phases in heterogeneous media. To attain this generality, a modification has been made to the original formula, such that the constant of proportionality between flow and hydraulic gradient is allowed to be a spatially varying function of the system properties. The extended version of Darcy’s law is expressed in the following form: qα=-Kα . Jα (2.1) where qα is the volumetric flow rate per unit area vector of the α-phase fluid, Kα is the hydraulic conductivity tensor of the α-phase and is a function of the viscosity and saturation of the α-phase and of the solid matrix, and Jα is the vector hydraulic gradient that drives the flow. The quantities Jα and Kα account for pressure and gravitational effects as well as the interactions that occur between adjacent phases. Although this generalization is occasionally criticized for its shortcomings, equation (2.1) is considered today to be a fundamental principle in analysis of porous media flows (e.g., McWhorter and Sunada, 1977). If, indeed, Darcy’s experimental result is the birth of quantitative hydrology, a need still remains to build quantitative analysis of porous media flow on a strong theoretical foundation. The problem of unsaturated flow of water has been attacked using experimental and theoretical tools since the early part of this century. Sposito (1986) attributes the beginnings of the study of soil water flow as a subdiscipline of physics to the fundamental work of Buckingham (1907), which uses a saturation-dependent hydraulic conductivity and a capillary potential for the hydraulic gradient.

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Pratumsuwan, Pornjit, and Chaiyapon Thongchaisuratkrul. "Pre-compensation for a Hybrid Fuzzy PID Control of a Proportional Hydraulic System." In PID Control, Implementation and Tuning. InTech, 2011. http://dx.doi.org/10.5772/15202.

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Тези доповідей конференцій з теми "Hydraulics proportional"

Naepfel, Rainer. "Special Applications in Mobile Hydraulics Including Electro-Hydraulic Proportional Technology." In 1985 SAE International Off-Highway and Powerplant Congress and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1985. http://dx.doi.org/10.4271/851492.

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Muschalle, Manfred, Wolfgang Petri, and Christer Fjellgren. "New Concepts of Proportional Pressure Reducing Valves (PPRVs) for Mobile Hydraulics." In International Off-Highway & Powerplant Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1998. http://dx.doi.org/10.4271/981969.

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Bartolj, Jan, Anže Čelik, and Franc Majdič. "Development of metallic 3d-printed water hydraulic proportional directional control valve." In International conference Fluid Power 2021. University of Maribor Press, 2021. http://dx.doi.org/10.18690/978-961-286-513-9.4.

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New additive metal powder technologies are increasingly used for various prototypes. Different powder materials can be used for very complex shapes. Water hydraulics needs new technologies and new approaches to enable more frequent use by users. A new shape of housing for a water hydraulic proportional directional control valve was designed. FEM and CFD analyses of the valve housing were performed. Based on the results of the initial numerical analyses, topological optimization of the valve housing was performed. The prototype of the valve was fabricated from non-corrosive Inconel powder using 3D printing process. After machining, the valve was assembled and experimentally validated on the water hydraulic test rig. The new 3D-printed Inconel valve housing is more than 3 times lighter than similar housings of industrial valves.

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Dong, Zhe. "Proportional-Integral Disturbance Observer of Nuclear Reactors." In 2020 International Conference on Nuclear Engineering collocated with the ASME 2020 Power Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icone2020-16207.

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Abstract A proportional-integral disturbance observer (PI-DO) for monitoring nuclear reactors is newly proposed, which is driven by the measurements of neutron flux and coolant temperature at reactor inlet as well as their integrations. This PI-DO provides a globally asymptotic estimation with a bounded steady-state error for the reactor key process variables as well as the total disturbances in channels of the neutron kinetics and primary coolant thermal-hydraulics. Moreover, the PI-DO is applied to reconstruct the unmeasurable state variables and total disturbances of a nuclear heating reactor (NHR). Numerical simulation results not only verify the theoretic analysis but also show both the satisfactory performance and the influence of observer parameters.

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Marani, Pietro, and Massimo Martelli. "Energy and Control Characteristics of a Novel Meter Out Hydraulic System for Mobile Applications." In ASME/BATH 2017 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fpmc2017-4269.

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The metering out sensing system represents the latest, and most promising, architectural concept for improving the performance of mobile multiple actuation systems through hydraulic proportional components control. The first part of the paper introduces the novel architecture of meter-out sensing control system, properly designed to distribute the flow rate directed to actuators according to the proportional control of the metering out element only. To do this, an innovative piloting subsystem controls the pump displacement, while a set of compensated proportional control valves applied to actuators outlet work to manage the load unbalance. The inlet doesn’t have any proportional throttle element thus reducing control losses with respect to state-of-the-art systems. In this way, the architecture is able to control both resisting and overrunning loads, and its design could easily include the automatic activation of the regenerative function to limit the requested hydraulic power. Then, the paper highlights how the proposed architecture of meter-out sensing system, which does not require complex sensor networks or complex electronic controls, could overcome the most important limitations affecting other control technologies currently adopted in mobile hydraulics. The third part of the paper depicts the main results obtained in the evaluation of the performance figures of merit for the metering out sensing system, performed through a Virtual Test Procedure applied to a lumped and distributed parameter numerical model.

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Yuan, Chenggang, Min Pan, and Andrew Plummer. "A Review of Switched Inertance Hydraulic Converter Technology." In BATH/ASME 2018 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fpmc2018-8829.

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Digital hydraulics is a new technology providing an alternative to conventional proportional or servovalve-controlled systems in the area of fluid power. Research is driven by the need for highly energy efficient hydraulic machines but is relatively immature compared to other energy-saving technologies. Digital hydraulic applications, such as digital pumps, digital valves and actuators, switched inertance hydraulic converters (SIHCs) and digital hydraulic power management systems, all promise high energy efficiency. This review introduces the development of SIHCs and evaluates the device configurations, performance and control strategies that are found in current SIHC research, particularly focusing on the work being undertaken in last 15 years. The designs for highspeed switching valves are evaluated, and their advantages and limitations are discussed. This article concludes with some suggestions for the future development of SIHCs.

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Leung, W. H. "On the MEGAPIE Target Thermal Hydraulics: A RELAP5 Analysis." In 12th International Conference on Nuclear Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/icone12-49378.

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A new type of liquid-metal target is designed for the Spallation Neutron Source in PSI. LBE is selected to be the target material and the primary coolant as well. RELAP5/MOD 3.2 is used to analyze the system thermal hydraulics. The nominal conditions are chosen based on temperature constraints from the design assessments. The steady state results are in the proximity of the design specifications and the heat removal capacity is adequately deployed. The normal thermal hydraulic transients, namely the proton beam and beam interrupt, are studied. A basic PID (Proportional, Integral, Derivative) control is implemented in the RELAP5 for regulating the target temperature. It is found that the control chain works very well for the beam trip in limiting the temperature fluctuations. In a beam interrupt, the proton beam is completely turned off without recovering. The transition from full power to hot-standby is quite smooth, but it becomes oscillatory in the long run due to the timelags in the cooling loops’ responses. An off normal case of target main coolant trip has also been studied. Without the main pump, the target can still be operated in the natural circulation mode, and the control can cope with the normal beam transients and restarting the target from hot standby.

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Huova, Mikko, Jyrki Tammisto, Matti Linjama, and Jussi Tervonen. "Fuel Efficiency Analysis of Selected Hydraulic Hybrids in a Wheel Loader Application." In BATH/ASME 2018 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fpmc2018-8869.

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There is a potential for significant improvement on fuel efficiency of many mobile machines by using hybrid technology as the Diesel engines are often driven at very inefficient operating points in these applications. The load generated by the working hydraulics of a mobile machine is often rapidly changing and contains high peak powers compared to the mean power required. This paper studies three different hydraulic hybrids in a wheel loader application. The study is based on a measured sand-loading Y-cycle. In addition to the hybrid systems, a load sensing proportional valve based reference machine and a modified machine based on independent metering valves are analyzed. All five system alternatives are analyzed systematically to enable a comparison of their fuel efficiency. The study shows that the fuel consumption of the machine can be decreased up to 28 % in such load cycle by using a suitable hydraulic hybrid system.

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Kogler, Helmut, Rudolf Scheidl, and Michael Ehrentraut. "A Simulation Model of a Hydraulic Buck Converter Based on a Mixed Time Frequency Domain Iteration." In ASME/BATH 2013 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fpmc2013-4409.

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Digital hydraulics is an opportunity to realize simple, robust, cheap and energy efficient hydraulic drives. In such systems digital on/off valves are used instead of proportional valves. Moreover, in hydraulic switching converters the valves are actuated within a few milliseconds, which create sharp pressure changes and, in turn, significant wave propagation effects in the pipe system. For a proper design of digital hydraulic systems a sound understanding of these effects is required to achieve the desired behavior of the switching drive system. In such converters, like the buck-, boost or boost-buck-converter, the inductance is one crucial component. It is realized by a simple pipe mainly for cost reasons. Furthermore, switching converters contain some components with nonlinear characteristics, like valves or accumulators, which prevent a comprehensive analysis in frequency domain. For a convenient analysis a qualified model of a hydraulic buck converter based on a mixed time frequency domain iteration is presented. Main parameters of this model are identified and wave propagation effects in the inductance pipe of the converter are investigated by simulation.

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Tatoglu, Akin, Claudio Campana, James Nolan, and Gary Toloczko. "Fuzzy Logic Controller Design of a Single Stage Fluid Valve Based Robotic Arm." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24145.

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Abstract One challenge for mobile robotics is the limitation of onboard processing power and the size of equipment required to accomplish basic tasks. While hydraulic pistons can generate high force output for various types of manipulation tasks, they require large equipment including the pistons, compressors, and the power sources in order to operate properly. For hydraulics to be applied to small to medium scale robots, the scale of the system needs to be as minimalistic as possible. For this purpose, we designed a single stage valve actuated robotic arm. Since system’s dynamic behavior is complex and only piston distance data is observable, a heuristic method, a Fuzzy Logic controller, is investigated. The goal is to create and optimize a system using a single piston and small compressor while maintaining effective control of the arm. Fuzzy Logic Controller system details, experimental setup and results are discussed for various motion profiles and finally its effectiveness is compared with a traditional PID controller approach. Robotics is a field that is constantly evolving and looking for creative new ways to provide solutions to new and old obstacles. One challenge for mobile robotics is the limitation of onboard processing power and the size of equipment required to accomplish basic tasks. The issue especially with smaller scale mobile robots is the lack of power and space on the robot to fit equipment and any critical apparatus for said equipment. While hydraulic pistons can generate high force output for various types of manipulation tasks, they require large equipment including pistons, compressors, and power sources in order to operate properly. Typically, a motor is used to power a pump which pressurizes hydraulic fluid. This fluid is used by the machine via hydraulic tubes and then is sent back through a filter and returns to the pump. This method of using hydraulics requires a large amount of power and a large amount of space. For hydraulics to be applied to small to medium scale robots, the scale of the system needs to be as minimalistic as possible. For this purpose, we designed a single stage valve actuated robotic arm. These employed the use of small electronic control boards fitted to the compressor system used to drive the hydraulics. For types of systems that must operate with discrete impulses of data to reach a target or reference value predominantly use Proportional-Integral-Derivative (PID) Controllers. These would be programmed in the onboard computer driving the hydraulic system. These systems require careful tweaking of various gain values to set up appropriately. However, the choice of an accurate controller structure relies on the application. Since system’s dynamic behavior is complex and only piston distance data is observable, an alternative method of control is investigated. Fuzzy logic is a control method which takes inputs from sensors and determines the output in terms of logical statements that can be in degrees between 0 and 1 rather than strictly 0 and 1 as seen in traditional Boolean logic. The particular equipment of interest in this study is a pneumatic robotic arm and all associated hardware. The goal is to create and optimize a system using a single piston and small compressor while maintaining effective control of the arm. Both a PID controller and a Fuzzy Logic controller were used to control the same system for the same set of tests. After PID control design approach is briefly discussed, Fuzzy Logic Controller system details, experimental setup and results are discussed for various motion profiles. Finally, the effectiveness of a traditional PID controller is compared to the effectiveness of a fuzzy logic controller.

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Звіти організацій з теми "Hydraulics proportional"

Montalvo-Bartolomei, Axel, Bryant Robbins, and Jamie López-Soto. Backward erosion progression rates from small-scale flume tests. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/42135.

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Backward erosion piping (BEP) is an internal erosion mechanism by which erosion channels progress upstream, typically through cohesionless or highly erodible foundation materials of dams and levees. As one of the primary causes of embankment failures, usually during high pool events, the probability of BEP-induced failure is commonly evaluated by the U.S. Army Corps of Engineers for existing dams and levees. In current practice, BEP failure probability is quantitatively assessed assuming steady state conditions with qualitative adjustments for temporal aspects of the process. In cases with short-term hydraulic loads, the progression rate of the erosion pipe may control the failure probability such that more quantitative treatment of the temporal development of erosion is necessary to arrive at meaningful probabilities of failure. This report builds upon the current state of the practice by investigating BEP progression rates through a series of laboratory experiments. BEP progression rates were measured for nine uniform sands in a series of 55 small-scale flume tests. Results indicate that the pipe progression rates are proportional to the seepage velocity and can be predicted using equations recently proposed in the literature.

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Snyder, Victor A., Dani Or, Amos Hadas, and S. Assouline. Characterization of Post-Tillage Soil Fragmentation and Rejoining Affecting Soil Pore Space Evolution and Transport Properties. United States Department of Agriculture, April 2002. http://dx.doi.org/10.32747/2002.7580670.bard.

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Tillage modifies soil structure, altering conditions for plant growth and transport processes through the soil. However, the resulting loose structure is unstable and susceptible to collapse due to aggregate fragmentation during wetting and drying cycles, and coalescense of moist aggregates by internal capillary forces and external compactive stresses. Presently, limited understanding of these complex processes often leads to consideration of the soil plow layer as a static porous medium. With the purpose of filling some of this knowledge gap, the objectives of this Project were to: 1) Identify and quantify the major factors causing breakdown of primary soil fragments produced by tillage into smaller secondary fragments; 2) Identify and quantify the. physical processes involved in the coalescence of primary and secondary fragments and surfaces of weakness; 3) Measure temporal changes in pore-size distributions and hydraulic properties of reconstructed aggregate beds as a function of specified initial conditions and wetting/drying events; and 4) Construct a process-based model of post-tillage changes in soil structural and hydraulic properties of the plow layer and validate it against field experiments. A dynamic theory of capillary-driven plastic deformation of adjoining aggregates was developed, where instantaneous rate of change in geometry of aggregates and inter-aggregate pores was related to current geometry of the solid-gas-liquid system and measured soil rheological functions. The theory and supporting data showed that consolidation of aggregate beds is largely an event-driven process, restricted to a fairly narrow range of soil water contents where capillary suction is great enough to generate coalescence but where soil mechanical strength is still low enough to allow plastic deforn1ation of aggregates. The theory was also used to explain effects of transient external loading on compaction of aggregate beds. A stochastic forInalism was developed for modeling soil pore space evolution, based on the Fokker Planck equation (FPE). Analytical solutions for the FPE were developed, with parameters which can be measured empirically or related to the mechanistic aggregate deformation model. Pre-existing results from field experiments were used to illustrate how the FPE formalism can be applied to field data. Fragmentation of soil clods after tillage was observed to be an event-driven (as opposed to continuous) process that occurred only during wetting, and only as clods approached the saturation point. The major mechanism of fragmentation of large aggregates seemed to be differential soil swelling behind the wetting front. Aggregate "explosion" due to air entrapment seemed limited to small aggregates wetted simultaneously over their entire surface. Breakdown of large aggregates from 11 clay soils during successive wetting and drying cycles produced fragment size distributions which differed primarily by a scale factor l (essentially equivalent to the Van Bavel mean weight diameter), so that evolution of fragment size distributions could be modeled in terms of changes in l. For a given number of wetting and drying cycles, l decreased systematically with increasing plasticity index. When air-dry soil clods were slightly weakened by a single wetting event, and then allowed to "age" for six weeks at constant high water content, drop-shatter resistance in aged relative to non-aged clods was found to increase in proportion to plasticity index. This seemed consistent with the rheological model, which predicts faster plastic coalescence around small voids and sharp cracks (with resulting soil strengthening) in soils with low resistance to plastic yield and flow. A new theory of crack growth in "idealized" elastoplastic materials was formulated, with potential application to soil fracture phenomena. The theory was preliminarily (and successfully) tested using carbon steel, a ductile material which closely approximates ideal elastoplastic behavior, and for which the necessary fracture data existed in the literature.

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