On Fluid Compressibility in Switch-Mode Hydraulic Circuits—Part I: Modeling and Analysis

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Computational Experiment ◽  
High Efficiency ◽  
Major Influence ◽  
Hydraulic Fluid ◽  
System Pressure ◽  
Switch Mode ◽  
Entrained Air ◽  
Hydraulic Circuits ◽  
Fluid Compressibility

Fluid compressibility has a major influence on the efficiency of switch-mode hydraulic circuits due to the release of energy stored in fluid compression during each switching cycle and the increased flow rate through the high-speed valve during transition events. Multiple models existing in the literature for fluid bulk modulus, the inverse of the compressibility, are reviewed and compared with regards to their applicability to a switch-mode circuit. In this work, a computational model is constructed of the primary energy losses in a generic switch-mode hydraulic circuit with emphasis on losses created by fluid compressibility. The model is used in a computational experiment where the system pressure, switched volume, and fraction of air entrained in the hydraulic fluid are varied through multiple levels. The computational experiments resulted in switch-mode circuit volumetric efficiencies that ranged from 51% to 95%. The dominant energy loss is due to throttling through the ports of the high-speed valve during valve transition events. The throttling losses increase with the fraction of entrained air and the volume of fluid experiencing pressure fluctuations, with a smaller overall influence seen as a result of the system pressure. The results of the computational experiment indicate that to achieve high efficiency in switch-mode hydraulic circuits, it is critical to minimize both the entrained air in the hydraulic fluid and the fluid volume between the high-speed valve and the pump, motor, or actuator. These computational results are compared with experimental results in Part II of this two part paper series.

On Fluid Compressibility in Switch-Mode Hydraulic Circuits—Part II: Experimental Results

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
James D. Van de Ven
Keyword(s):  
Computational Model ◽  
Experimental Work ◽  
Experimental System ◽  
Experimental Results ◽  
System Pressure ◽  
Switch Mode ◽  
Air System ◽  
Entrained Air ◽  
Hydraulic Circuits ◽  
Fluid Compressibility

In this paper, the author presents experimental work with a generic switch-mode hydraulic circuit that aims to validate a previously presented computational model, with primary focus on the energy loss due to fluid compressibility. While multiple previous papers have presented experimental works with switch-mode hydraulic circuits, the presented experimental system is unique due the capability of in-flow measurement of the entrained air in the hydraulic fluid. A designed experiment was run that varied the entrained air, system pressure, and volume of the fluid experiencing pressure fluctuations, defined as the switched volume. The calculated volumetric efficiency from these experiments ranged from to 61% to 75%, with efficiency increasing with decreased levels of entrained air, system pressure, and switched volume. These efficiency trends and the pressure profile in the switched volume agree well with the computational model presented in Part I of this two part set (Van de Ven, 2013, “On Fluid Compressibility in Switch-Mode Hydraulic Circuits—Part I: Modeling and Analysis,” ASME J. Dyn. Sys., Meas., Control, 135(2), p. 021013). Differences between the experimental results and the computational model include approximately 10% higher predicted efficiency and pressure oscillations found in the experimental work that were not predicted by the model.

Development of a High-Speed On-Off Valve for Switch-Mode Control of Hydraulic Circuits With Four-Quadrant Control

2010 ◽  
Author(s):  
Jeslin J. Wu ◽  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Average Power ◽  
Viscous Friction ◽  
Valve Design ◽  
Rotating Disc ◽  
Mode Control ◽  
Switch Mode ◽  
Variable Displacement ◽  
Four Quadrant ◽  
Hydraulic Circuits

Hydraulic circuits are typically controlled by throttling valves or variable displacement pump/motors. The first method throttles fluid for a desired pressure output and excess energy is lost through heat. While variable displacement pumps are more efficient, they are often large and expensive. An alternate method is the switch-mode control of hydraulic circuits through high-speed on-off valves. The proposed on-off valve design makes use of a continuously rotating disc to modulate flow between on and off states; the average power output or pulse duration is determined by the relative phase shift between the input and output ports. The addition of a directional valve to the the high-speed three-way valve allows any fixed displacement actuator to behave like a virtually variable displacement unit that is capable of four-quadrant control. In this paper a mathematical model focusing on the throttling, compressibility, internal leakage and viscous friction losses is developed and utilized to optimize the valve design for highest efficiency.

Based on Fluid Digital Transmission and Control Theory on Application of Digital Hydraulic Valve

2012 ◽  
Vol 619 ◽  
pp. 455-458
Author(s):  
Wen Hua Li ◽  
Yu Ling Du
Keyword(s):  
Control Theory ◽  
Hydraulic System ◽  
High Speed ◽  
High Efficiency ◽  
Simulation Analysis ◽  
High Reliability ◽  
Electronic Control Unit ◽  
System Pressure ◽  
Analysis Experiment ◽  
Hydraulic Valve

A digital hydraulic valve is a new control theory and method, it is through the electronic control unit installed in a conventional valve, and integrated processing, the formation of a wide variety of digital valve，By the digital-to-analog conversion element is directly connected with the computer. Using the computer output pulse number and frequency to control electro hydraulic system pressure and measurement. The system proposed can make the hydraulic system has the advantages of high efficiency, high speed, high reliability. And used Matlab/Simulink software to control system performance simulation analysis, experiment and simulation results show that, this system has great application prospect and practical value.

Soft Switch Lock-Release Mechanism for a Switch-Mode Hydraulic Pump Circuit

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
James D. Van de Ven
Keyword(s):  
High Speed ◽  
Soft Switching ◽  
Proper Function ◽  
Energy Losses ◽  
Release Mechanism ◽  
Soft Switch ◽  
Locking Mechanism ◽  
Duty Cycles ◽  
Switch Mode ◽  
Hydraulic Circuits

Switch-mode hydraulic circuits are a theoretically efficient, compact, fast responding, and inexpensive control option. Despite the many potential benefits of switch-mode hydraulic circuits, the control method suffers from large energy losses during transitions of the high-speed valve due to throttling and fluid compressibility. Rannow and Li previously proposed utilizing soft switching to minimize the throttling energy loss (Rannow and Li, “Soft Switching Approach to Reducing Transition Losses in On/Off Hydraulic Valve,” J. Dyn. Syst., Measure. Control (in press)). A major challenge of this approach is a locking soft switch that releases quickly and with precise timing, while under load. In this paper, a novel soft switch locking mechanism is presented that utilizes the pressure signal in the switched volume to trigger the release. A dynamic model is developed of three unique soft switch circuits and two control circuits that create a virtually variable displacement pump. The model is used to perform a grid search optimization of the soft switch parameters for the three circuits. The three soft switch circuits reduce the throttling and compressibility energy losses between 49% and 66% compared with the control circuit. The simulation results demonstrated that the soft switch circuits perform as expected for duty cycles and pressures below the design conditions. At higher duty cycles and pressures, the short time the circuit is connected to tank prevented the soft switches from resetting between cycles, preventing proper function. This novel lock and release soft switch mechanism enables soft switching in switch-mode hydraulic circuits, which significantly reduces throttling and compressibility energy losses during valve transitions. Lower losses during valve transition allow the use of slower switching valves, lowering energy consumption, and cost.

One-step Separation and Purification of Four Phenolic Acids from Stenoloma chusanum (L.) Ching by Medium-pressure Liquid Chromatography and High-speed Counter-current Chromatography

2019 ◽  
Vol 9 (2) ◽  
pp. 138-143
Author(s):  
Tianyun Li ◽  
Xiling Dai ◽  
Yichen Li ◽  
Guozheng Huang ◽  
Jianguo Cao
Keyword(s):  
Natural Products ◽  
Liquid Chromatography ◽  
Phenolic Acids ◽  
High Speed ◽  
High Efficiency ◽  
Total Phenolic ◽  
Medium Pressure ◽  
Medium Pressure Liquid Chromatography ◽  
One Step ◽  
Counter Current

Background:Stenoloma chusanum (L.) Ching is a Chinese traditional medicinal fern with high total flavonoid and total phenolic content. Traditionally, phenolic compounds were separated by using column chromatography, which is relatively inefficient. </P><P> Objective: This study aims to use an efficient method to separate natural products from S. chusanum by Medium-Pressure Liquid Chromatography (MPLC) and High-Speed Counter-Current Chromatography (HSCCC).Methods:In the present research, firstly, a sample (2.5 g) from the dichloromethane extract of S. chusanum was separated by MPLC. Next, fraction P5 was purified by HSCCC with a two-phase solvent system composed of hexane-ethyl acetate-methanol-water (HEMWat) at a volume ratio of 2:4:1:4 (v/v/v/v). </P><P> Result: Four phenolic acids were obtained and their structures were identified by means of NMR and ESI-mass analysis. They were identified as: 1) protocatechuic acid (34 mg, purity 90.1%), 2) syringic acid (66 mg, purity 99.0%), 3) p-hydroxybenzoic acid (5 mg, purity 91.2%) and 4) vanillic acid (6 mg, purity 99.3%).Conclusion:The combination of MPLC and HSCCC is a high-efficiency separation method for natural products. This is the first report with regard to the separation of four phenolic acids in one step by MPLC and HSCCC from S. chusanum (L.) Ching.

scholarly journals On-chip trans-dimensional plasmonic router

Nanophotonics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 3357-3365 ◽  
Author(s):  
Shaohua Dong ◽  
Qing Zhang ◽  
Guangtao Cao ◽  
Jincheng Ni ◽  
Ting Shi ◽  
...  
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Incident Angle ◽  
Reciprocal Lattice ◽  
Plasmonic Waveguide ◽  
Optical Diffraction ◽  
Local Dynamic ◽  
Phase Gradient ◽  
On Chip ◽  
Plasmon Polaritons

AbstractPlasmons, as emerging optical diffraction-unlimited information carriers, promise the high-capacity, high-speed, and integrated photonic chips. The on-chip precise manipulations of plasmon in an arbitrary platform, whether two-dimensional (2D) or one-dimensional (1D), appears demanding but non-trivial. Here, we proposed a meta-wall, consisting of specifically designed meta-atoms, that allows the high-efficiency transformation of propagating plasmon polaritons from 2D platforms to 1D plasmonic waveguides, forming the trans-dimensional plasmonic routers. The mechanism to compensate the momentum transformation in the router can be traced via a local dynamic phase gradient of the meta-atom and reciprocal lattice vector. To demonstrate such a scheme, a directional router based on phase-gradient meta-wall is designed to couple 2D SPP to a 1D plasmonic waveguide, while a unidirectional router based on grating metawall is designed to route 2D SPP to the arbitrarily desired direction along the 1D plasmonic waveguide by changing the incident angle of 2D SPP. The on-chip routers of trans-dimensional SPP demonstrated here provide a flexible tool to manipulate propagation of surface plasmon polaritons (SPPs) and may pave the way for designing integrated plasmonic network and devices.

scholarly journals Optimization of Air Gap Length and Capacitive Auxiliary Winding in Three-Phase Induction Motors Based on a Genetic Algorithm

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4407
Author(s):  
Mbika Muteba
Keyword(s):  
Genetic Algorithm ◽  
Design Process ◽  
Power Factor ◽  
High Speed ◽  
High Efficiency ◽  
Air Gap ◽  
Element Analysis ◽  
Three Phase ◽  
High Torque ◽  
Cage Induction Motor

There is a necessity to design a three-phase squirrel cage induction motor (SCIM) for high-speed applications with a larger air gap length in order to limit the distortion of air gap flux density, the thermal expansion of stator and rotor teeth, centrifugal forces, and the magnetic pull. To that effect, a larger air gap length lowers the power factor, efficiency, and torque density of a three-phase SCIM. This should inform motor design engineers to take special care during the design process of a three-phase SCIM by selecting an air gap length that will provide optimal performance. This paper presents an approach that would assist with the selection of an optimal air gap length (OAL) and optimal capacitive auxiliary stator winding (OCASW) configuration for a high torque per ampere (TPA) three-phase SCIM. A genetic algorithm (GA) assisted by finite element analysis (FEA) is used in the design process to determine the OAL and OCASW required to obtain a high torque per ampere without compromising the merit of achieving an excellent power factor and high efficiency for a three-phase SCIM. The performance of the optimized three-phase SCIM is compared to unoptimized machines. The results obtained from FEA are validated through experimental measurements. Owing to the penalty functions related to the value of objective and constraint functions introduced in the genetic algorithm model, both the FEA and experimental results provide evidence that an enhanced torque per ampere three-phase SCIM can be realized for a large OAL and OCASW with high efficiency and an excellent power factor in different working conditions.

scholarly journals Research on Distance Transform and Neural Network Lidar Information Sampling Classification-Based Semantic Segmentation of 2D Indoor Room Maps

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1365
Author(s):  
Tao Zheng ◽  
Zhizhao Duan ◽  
Jin Wang ◽  
Guodong Lu ◽  
Shengjie Li ◽  
...  
Keyword(s):  
Neural Network ◽  
High Speed ◽  
High Performance ◽  
High Efficiency ◽  
Semantic Segmentation ◽  
Raspberry Pi ◽  
Distance Transform ◽  
Testing Stage ◽  
Sampling Points ◽  
Information Sampling

Semantic segmentation of room maps is an essential issue in mobile robots’ execution of tasks. In this work, a new approach to obtain the semantic labels of 2D lidar room maps by combining distance transform watershed-based pre-segmentation and a skillfully designed neural network lidar information sampling classification is proposed. In order to label the room maps with high efficiency, high precision and high speed, we have designed a low-power and high-performance method, which can be deployed on low computing power Raspberry Pi devices. In the training stage, a lidar is simulated to collect the lidar detection line maps of each point in the manually labelled map, and then we use these line maps and the corresponding labels to train the designed neural network. In the testing stage, the new map is first pre-segmented into simple cells with the distance transformation watershed method, then we classify the lidar detection line maps with the trained neural network. The optimized areas of sparse sampling points are proposed by using the result of distance transform generated in the pre-segmentation process to prevent the sampling points selected in the boundary regions from influencing the results of semantic labeling. A prototype mobile robot was developed to verify the proposed method, the feasibility, validity, robustness and high efficiency were verified by a series of tests. The proposed method achieved higher scores in its recall, precision. Specifically, the mean recall is 0.965, and mean precision is 0.943.

The Role of Porous Media in Homogenization of High Pressure Diesel Fuel Spray Combustion

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Navid Shahangian ◽  
Damon Honnery ◽  
Jamil Ghojel
Keyword(s):  
High Pressure ◽  
Porous Media ◽  
High Speed ◽  
Fuel Spray ◽  
Compression Ignition Engines ◽  
System Pressure ◽  
Novel Approach ◽  
Air Mixing ◽  
The Media

Interest is growing in the benefits of homogeneous charge compression ignition engines. In this paper, we investigate a novel approach to the development of a homogenous charge-like environment through the use of porous media. The primary purpose of the media is to enhance the spread as well as the evaporation process of the high pressure fuel spray to achieve charge homogenization. In this paper, we show through high speed visualizations of both cold and hot spray events, how porous media interactions can give rise to greater fuel air mixing and what role system pressure and temperature plays in further enhancing this process.

scholarly journals High-speed high-efficiency large-area resonant cavity enhanced p-i-n photodiodes for multimode fiber communications

2001 ◽  
Vol 13 (12) ◽  
pp. 1349-1351 ◽  
Author(s):  
M. Gokkavas ◽  
O. Dosunmu ◽  
M.S. Unlu ◽  
G. Ulu ◽  
R.P. Mirin ◽  
...  
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Resonant Cavity ◽  
Multimode Fiber ◽  
Large Area ◽  
Fiber Communications
Sign in / Sign up

Export Citation Format

Share Document