Effective soil hydraulic conductivity predicted with the maximum power principle
Westhoff, Martijn; Erpicum, Sébastien; Archambeau, Pierre; Pirotton, Michel; Zehe, Erwin; Dewals, Benjamin
2016-04-01
Drainage of water in soils happens for a large extent through preferential flowpaths, but these subsurface flowpaths are extremely difficult to observe or parameterize in hydrological models. To potentially overcome this problem, thermodynamic optimality principles have been suggested to predict effective parametrization of these (sub-grid) structures, such as the maximum entropy production principle or the equivalent maximum power principle. These principles have been successfully applied to predict heat transfer from the Equator to the Poles, or turbulent heat fluxes between the surface and the atmosphere. In these examples, the effective flux adapts itself to its boundary condition by adapting its effective conductance through the creation of e.g. convection cells. However, flow through porous media, such as soils, can only quickly adapt its effective flow conductance by creation of preferential flowpaths, but it is unknown if this is guided by the aim to create maximum power. Here we show experimentally that this is indeed the case: In the lab, we created a hydrological analogue to the atmospheric model dealing with heat transport between Equator and poles. The experimental setup consists of two freely draining reservoirs connected with each other by a confined aquifer. By adding water to only one reservoir, a potential difference will build up until a steady state is reached. From the steady state potential difference and the observed flow through the aquifer, and effective hydraulic conductance can be determined. This observed conductance does correspond to the one maximizing power of the flux through the confined aquifer. Although this experiment is done in an idealized setting, it opens doors for better parameterizing hydrological models. Furthermore, it shows that hydraulic properties of soils are not static, but they change with changing boundary conditions. A potential limitation to the principle is that it only applies to steady state conditions
Analysis of Innovative Design of Energy Efficient Hydraulic Actuators
M Osman Abdalla
2013-01-01
Hydraulic cylinder actuators are used extensively in industrial, construction and agricultural works. The small sized outlet ports of the cylinders resist the flow of discharged oil; and as a result the piston motion is slowed down. This causes a lot of heat generation and energy loss within the actuators. The study investigates and analyzes the possibilities of reducing the hydraulic resistance and increasing efficiency of the hydraulic actuator. Conventional hydraulic cylinders are simulate...
Quantifying the Efficiency Advantages of High Viscosity Index Hydraulic Fluids
Christian D. Neveu; Michael D. Zink; Alex Tsay
2006-01-01
By providing higher in- use viscosity at elevated operating temperatures, hydraulic fluids with high viscosity index improve the efficiency of the hydraulic system. For mobile hydraulic equipment this efficiency can be quantified as an increase in fuel economy. This paper reviews the research that demonstrates these efficiency advantages in gear, vane and piston pumps and presents a method for predicting the overall fuel economy for a fleet of hydraulic equipment in opquipment operator to easily improve the performance of the system and reduce fuel consumption.
Analysis of Innovative Design of Energy Efficient Hydraulic Actuators
M Osman Abdalla
2013-01-01
Full Text Available Hydraulic cylinder actuators are used extensively in industrial, construction and agricultural works. The small sized outlet ports of the cylinders resist the flow of discharged oil; and as a result the piston motion is slowed down. This causes a lot of heat generation and energy loss within the actuators. The study investigates and analyzes the possibilities of reducing the hydraulic resistance and increasing efficiency of the hydraulic actuator. Conventional hydraulic cylinders are simulated in FLUENT. Results show that the small outlet ports are the sources of energy loss in hydraulic cylinders. A new hydraulic system was proposed as a solution to relieve the hydraulic resistance in the actuators. The proposed system is a four ports hydraulic cylinder fitted with a novel flow control valve. The proposed four ports cylinder was simulated and parameters such as ports sizes, loads and pressures are varied during the simulation. The hydraulic resisting forces, piston speed and mass flow rates are computed. Results show that the hydraulic resistance is significantly reduced in the proposed four ports actuators; and the proposed cylinders run faster than the conventional cylinders and a considerable amount of energyis saved as well.
[Effect of hydraulic load distribution on sewage treatment efficiency of earthworm bio-filter].
Yang, Jian; Yang, Jian; Yang, Ju-Chuan; Chen, Qiao-Yan; Lou, Shan-Jie
2008-07-01
Effect of hydraulic load distribution on sewage treatment efficiency of earthworm bio-filter was studied by analyzing influent and effluent of earthworm bio-filter and earthworm behaviors. The results show that when hydraulic load varying from 2.0 m3/(m2 x d) to 6.0 m3/(m2 x d), the concentration of each pollutant in earthworm bio-filter effluent increases slowly and is little effected by hydraulic load. When hydraulic load reaches 6.7 m3/(m2 x d), the concentration of COD, BOD5, SS, NH4(+) -N and TP in earthworm bio-filter effluent increases obviously, but the TN concentration in effluent presents descending tendency. The earthworms become rather inadaptable to the living conditions at this operating mode. As hydraulic load increasing, the earthworms' relative ingestive ability is improved at first, and then decreases. The earthworms' relative ingestive ability comes to the maximum at hydraulic load of 4.8 m3/(m2 x d), with good organic removal efficiency. The relation ships between hydraulic load and average weight, average density, unit-area biomass of the earthworms are significant negative correlation. The hydraulic load of 4.8 m3/(m2 x d) is recommended, but not over 6.7 m3/(m2 x d).
Efficiency limit factor analysis for the Francis-99 hydraulic turbine
Zeng, Y.; Zhang, L. X.; Guo, J. P.; Guo, Y. K.; Pan, Q. L.; Qian, J.
2017-01-01
The energy loss in hydraulic turbine is the most direct factor that affects the efficiency of the hydraulic turbine. Based on the analysis theory of inner energy loss of hydraulic turbine, combining the measurement data of the Francis-99, this paper calculates characteristic parameters of inner energy loss of the hydraulic turbine, and establishes the calculation model of the hydraulic turbine power. Taken the start-up test conditions given by Francis-99 as case, characteristics of the inner energy of the hydraulic turbine in transient and transformation law are researched. Further, analyzing mechanical friction in hydraulic turbine, we think that main ingredients of mechanical friction loss is the rotation friction loss between rotating runner and water body, and defined as the inner mechanical friction loss. The calculation method of the inner mechanical friction loss is given roughly. Our purpose is that explore and research the method and way increasing transformation efficiency of water flow by means of analysis energy losses in hydraulic turbine.
Energy Efficiency Comparison between Hydraulic Hybrid and Hybrid Electric Vehicles
Jia-Shiun Chen
2015-05-01
Full Text Available Conventional vehicles tend to consume considerable amounts of fuel, which generates exhaust gases and environmental pollution during intermittent driving cycles. Therefore, prospective vehicle designs favor improved exhaust emissions and energy consumption without compromising vehicle performance. Although pure electric vehicles feature high performance and low pollution characteristics, their limitations are their short driving range and high battery costs. Hybrid electric vehicles (HEVs are comparatively environmentally friendly and energy efficient, but cost substantially more compared with conventional vehicles. Hydraulic hybrid vehicles (HHVs are mainly operated using engines, or using alternate combinations of engine and hydraulic power sources while vehicles accelerate. When the hydraulic system accumulator is depleted, the conventional engine reengages; concurrently, brake-regenerated power is recycled and reused by employing hydraulic motor–pump modules in circulation patterns to conserve fuel and recycle brake energy. This study adopted MATLAB Simulink to construct complete HHV and HEV models for backward simulations. New European Driving Cycles were used to determine the changes in fuel economy. The output of power components and the state-of-charge of energy could be retrieved. Varying power component models, energy storage component models, and series or parallel configurations were combined into seven different vehicle configurations: the conventional manual transmission vehicle, series hybrid electric vehicle, series hydraulic hybrid vehicle, parallel hybrid electric vehicle, parallel hydraulic hybrid vehicle, purely electric vehicle, and hydraulic-electric hybrid vehicle. The simulation results show that fuel consumption was 21.80% lower in the series hydraulic hybrid vehicle compared to the series hybrid electric vehicle; additionally, fuel consumption was 3.80% lower in the parallel hybrid electric vehicle compared to the
Iden, Sascha; Peters, Andre; Durner, Wolfgang
2017-04-01
Soil hydraulic properties are required to solve the Richards equation, the most widely applied model for variably-saturated flow. While the experimental determination of the water retention curve does not pose significant challenges, the measurement of unsaturated hydraulic conductivity is time consuming and costly. The prediction of the unsaturated hydraulic conductivity curve from the soil water retention curve by pore-bundle models is a cost-effective and widely applied technique. A well-known problem of conductivity prediction for retention functions with wide pore-size distributions is the sharp drop in conductivity close to water saturation. This problematic behavior is well known for the van Genuchten model if the shape parameter n assumes values smaller than about 1.3. So far, the workaround for this artefact has been to introduce an explicit air-entry value into the capillary saturation function. However, this correction leads to a retention function which is not continuously differentiable and thus a discontinuous water capacity function. We present an improved parametrization of the hydraulic properties which uses the original capillary saturation function and introduces a maximum pore radius only in the pore-bundle model. Closed-form equations for the hydraulic conductivity function were derived for the unimodal and multimodal retention functions of van Genuchten and have been tested by sensitivity analysis and applied in curve fitting and inverse modeling of multistep outflow experiments. The resulting hydraulic conductivity function is smooth, increases monotonically close to saturation, and eliminates the sharp drop in conductivity close to saturation. Furthermore, the new model retains the smoothness and continuous differentiability of the water retention curve. We conclude that the resulting soil hydraulic functions are physically more reasonable than the ones predicted by previous approaches, and are thus ideally suited for numerical simulations
Effect of filter designs on hydraulic properties and well efficiency.
Kim, Byung-Woo
2014-09-01
To analyze the effect of filter pack arrangement on the hydraulic properties and the well efficiency of a well design, a step drawdown was conducted in a sand-filled tank model. Prior to the test, a single filter pack (SFP), granule only, and two dual filter packs (DFPs), type A (granule-pebble) and type B (pebble-granule), were designed to surround the well screen. The hydraulic properties and well efficiencies related to the filter packs were evaluated using the Hazen's, Eden-Hazel's, Jacob's, and Labadie-Helweg's methods. The results showed that the hydraulic properties and well efficiency of the DFPs were higher than those of a SFP, and the clogging effect and wellhead loss related to the aquifer material were the lowest owing to the grain size and the arrangement of the filter pack. The hydraulic conductivity of the DFPs types A and B was about 1.41 and 6.43 times that of a SFP, respectively. In addition, the well efficiency of the DFPs types A and B was about 1.38 and 1.60 times that of the SFP, respectively. In this study, hydraulic property and well efficiency changes were observed according to the variety of the filter pack used. The results differed from the predictions of previous studies on the grain-size ratio. Proper pack-aquifer ratios and filter pack arrangements are primary factors in the construction of efficient water wells, as is the grain ratio, intrinsic permeability (k), and hydraulic conductivity (K) between the grains of the filter packs and the grains of the aquifer. © 2014, National Ground Water Association.
Iden, Sascha C.; Peters, Andre; Durner, Wolfgang
2015-11-01
The prediction of unsaturated hydraulic conductivity from the soil water retention curve by pore-bundle models is a cost-effective and widely applied technique. One problem for conductivity predictions from retention functions with continuous derivatives, i.e. continuous water capacity functions, is that the hydraulic conductivity curve exhibits a sharp drop close to water saturation if the pore-size distribution is wide. So far this artifact has been ignored or removed by introducing an explicit air-entry value into the capillary saturation function. However, this correction leads to a retention function which is not continuously differentiable. We present a new parameterization of the hydraulic properties which uses the original saturation function (e.g. of van Genuchten) and introduces a maximum pore radius only in the pore-bundle model. In contrast to models using an explicit air entry, the resulting conductivity function is smooth and increases monotonically close to saturation. The model concept can easily be applied to any combination of retention curve and pore-bundle model. We derive closed-form expressions for the unimodal and multimodal van Genuchten-Mualem models and apply the model concept to curve fitting and inverse modeling of a transient outflow experiment. Since the new model retains the smoothness and continuous differentiability of the retention model and eliminates the sharp drop in conductivity close to saturation, the resulting hydraulic functions are physically more reasonable and ideal for numerical simulations with the Richards equation or multiphase flow models.
Improving energy efficiency in robot limbs through hydraulic dangle
Whitman, Julian S.; Meller, Mike; Garcia, Ephrahim
2015-03-01
Animals often allow their limbs to swing passively under their own inertia. For example, about 40% of a human walking gait consists of the primarily passive swing phase. Current hydraulic robots employ traditional actuation methods in which fluid power is expended for all limb movements, even when passive dynamics could be utilized. "Dangle" is the ability to allow a hydraulic actuator to freely sway in response to external loads, in which both sides of the actuator are disconnected from pressure and connected to the tank. Dangle offers the opportunity for efficiency gains by enabling the use of momentum, gravity, and external loads to move a limb without expending fluid power. To demonstrate these efficiency gains, this paper presents an experiment that compares the fluid power consumed to actuate a two degree of freedom hydraulic leg following a human walking gait cycle trajectory in both a traditional manner and utilizing dangle. It was shown that the use of dangle can decrease fluid power consumption by 20% by utilizing pendular dynamics during the swing phase. At speeds higher than the free dangling rate, more power must be used to maintain the desired trajectory due to damping inherent in the configuration. The use of dangle as a power saving method when driving hydraulic limbs could increase operation time for untethered hydraulic walking robots.
Transport efficiency and dynamics of hydraulic fracture networks
Sachau, Till; Bons, Paul; Gomez-Rivas, Enrique
2015-08-01
Intermittent fluid pulses in the Earth's crust can explain a variety of geological phenomena, for instance the occurrence of hydraulic breccia. Fluid transport in the crust is usually modeled as continuous darcian flow, ignoring that sufficient fluid overpressure can cause hydraulic fractures as fluid pathways with very dynamic behavior. Resulting hydraulic fracture networks are largely self-organized: opening and healing of hydraulic fractures depends on local fluid pressure, which is, in turn, largely controlled by the fracture network. We develop a crustal-scale 2D computer model designed to simulate this process. To focus on the dynamics of the process we chose a setup as simple as possible. Control factors are constant overpressure at a basal fluid source and a constant 'viscous' parameter controlling fracture-healing. Our results indicate that at large healing rates hydraulic fractures are mobile, transporting fluid in intermittent pulses to the surface and displaying a 1/fα behavior. Low healing rates result in stable networks and constant flow. The efficiency of the fluid transport is independent from the closure dynamics of veins or fractures. More important than preexisting fracture networks is the distribution of fluid pressure. A key requirement for dynamic fracture networks is the presence of a fluid pressure gradient.
Transport efficiency and dynamics of hydraulic fracture networks
Till eSachau
2015-08-01
Full Text Available Intermittent fluid pulses in the Earth's crust can explain a variety of geological phenomena, for instance the occurrence of hydraulic breccia. Fluid transport in the crust is usually modeled as continuous darcian flow, ignoring that sufficient fluid overpressure can cause hydraulic fractures as fluid pathways with very dynamic behavior. Resulting hydraulic fracture networks are largely self-organized: opening and healing of hydraulic fractures depends on local fluid pressure, which is, in turn, largely controlled by the fracture network. We develop a crustal-scale 2D computer model designed to simulate this process. To focus on the dynamics of the process we chose a setup as simple as possible. Control factors are constant overpressure at a basal fluid source and a constant 'viscous' parameter controlling fracture-healing. Our results indicate that at large healing rates hydraulic fractures are mobile, transporting fluid in intermittent pulses to the surface and displaying a 1/fα behavior. Low healing rates result in stable networks and constant flow. The efficiency of the fluid transport is independent from the closure dynamics of veins or fractures. More important than preexisting fracture networks is the distribution of fluid pressure. A key requirement for dynamic fracture networks is the presence of a fluid pressure gradient.
Efficiency at Maximum Power of Interacting Molecular Machines
Golubeva, Natalia; Imparato, Alberto
2012-01-01
We investigate the efficiency of systems of molecular motors operating at maximum power. We consider two models of kinesin motors on a microtubule: for both the simplified and the detailed model, we find that the many-body exclusion effect enhances the efficiency at maximum power of the many- motor...... system, with respect to the single motor case. Remarkably, we find that this effect occurs in a limited region of the system parameters, compatible with the biologically relevant range....
Nanocoatings for High-Efficiency Industrial Hydraulic and Tooling Systems
Clifton B. Higdon III
2011-01-07
Industrial manufacturing in the U.S. accounts for roughly one third of the 98 quadrillion Btu total energy consumption. Motor system losses amount to 1.3 quadrillion Btu, which represents the largest proportional loss of any end-use category, while pumps alone represent over 574 trillion BTU (TBTU) of energy loss each year. The efficiency of machines with moving components is a function of the amount of energy lost to heat because of friction between contacting surfaces. The friction between these interfaces also contributes to downtime and the loss of productivity through component wear and subsequent repair. The production of new replacement parts requires additional energy. Among efforts to reduce energy losses, wear-resistant, low-friction coatings on rotating and sliding components offer a promising approach that is fully compatible with existing equipment and processes. In addition to lubrication, one of the most desirable solutions is to apply a protective coating or surface treatment to rotating or sliding components to reduce their friction coefficients, thereby leading to reduced wear. Historically, a number of materials such as diamond-like carbon (DLC), titanium nitride (TiN), titanium aluminum nitride (TiAlN), and tungsten carbide (WC) have been examined as tribological coatings. The primary objective of this project was the development of a variety of thin film nanocoatings, derived from the AlMgB14 system, with a focus on reducing wear and friction in both industrial hydraulics and cutting tool applications. Proof-of-concept studies leading up to this project had shown that the constituent phases, AlMgB14 and TiB2, were capable of producing low-friction coatings by pulsed laser deposition. These coatings combine high hardness with a low friction coefficient, and were shown to substantially reduce wear in laboratory tribology tests. Selection of the two applications was based largely on the concept of improved mechanical interface efficiencies for
Decker, Robert L.; Kirby, Klane
This curriculum guide contains a course in hydraulics to train entry-level workers for automotive mechanics and other fields that utilize hydraulics. The module contains 14 instructional units that cover the following topics: (1) introduction to hydraulics; (2) fundamentals of hydraulics; (3) reservoirs; (4) lines, fittings, and couplers; (5)…
Efficiency of autonomous soft nanomachines at maximum power.
Seifert, Udo
2011-01-14
We consider nanosized artificial or biological machines working in steady state enforced by imposing nonequilibrium concentrations of solutes or by applying external forces, torques, or electric fields. For unicyclic and strongly coupled multicyclic machines, efficiency at maximum power is not bounded by the linear response value 1/2. For strong driving, it can even approach the thermodynamic limit 1. Quite generally, such machines fall into three different classes characterized, respectively, as "strong and efficient," "strong and inefficient," and "balanced." For weakly coupled multicyclic machines, efficiency at maximum power has lost any universality even in the linear response regime.
Turbine efficiency test on a large hydraulic turbine unit
YAN ZongGuo; ZHOU LingJiu; WANG ZhengWei
2012-01-01
The flow rate measurements are the most difficult part of efficiency tests on prototype hydraulic turbines.Among the numerous flow rate measurement methods,the Winter Kennedy method is preferred for measuring turbine flow rates,since it is convenient,practical and economical.This paper describes efficiency tests on a large 300 MW Francis turbine,with the flow rate measured using the Winter Kennedy method and the Winter Kennedy flow rate coefficient calibrated using the Gibson method.The measured turbine efficiency curve is then compared with the curve provided by the manufacturer.The CFD calculations including the spiral case are then used to analyze the influence with the coefficient K and index n in the Winter Kennedy flow rate formula on the flow rate measurement.The uncertainty values of n and K are a key reason for the differences between the curves obtained from the efficiency test and the curves provided by the manufacturer.
In-Plant Testing of High-Efficiency Hydraulic Separators
G. H. Luttrell; R. Q. Honaker; R. C. Bratton; T. C. Westerfield; J. N. Kohmuench
2006-06-30
Hydraulic separators are commonly used for particle size classification and gravity concentration of minerals and coal. Unfortunately, the efficiency of these processes can be quite low due to poor equipment design and variations in feed consistency. To help alleviate these problems, an industry-driven R&D program has been undertaken to develop a new generation of hydraulic separators that are more efficient and less costly to operate and maintain. These units, which are commercially called the CrossFlow separator and HydroFloat separator, have the potential to improve performance (separation efficiency and throughput) and reduce operating costs (power consumption, water and reagent usage). In Phase I of this project, laboratory and pilot-scale test units were evaluated at various industrial sites in both the coal and mineral industries. Based on promising results obtained from Phase I, full-scale prototypes were purchased and installed by a major U.S. phosphate producer and a large eastern U.S. coal company. The test data obtained from these sites demonstrate that significant performance improvements can be realized through the application of these high-efficiency separators.
IN-PLANT TESTING OF HIGH-EFFICIENCY HYDRAULIC SEPARATORS
G.H. Luttrell; R.Q. Honaker; R.C. Bratton; T.C. Westerfield; J.N. Kohmuench
2006-05-22
Hydraulic separators are commonly used for particle size classification and gravity concentration of minerals and coal. Unfortunately, the efficiency of these processes can be quite low due to poor equipment design and variations in feed consistency. To help alleviate these problems, an industry-driven R&D program has been undertaken to develop a new generation of hydraulic separators that are more efficient and less costly to operate and maintain. These units, which are commercially called the CrossFlow separator and HydroFloat separator, have the potential to improve performance (separation efficiency and throughput) and reduce operating costs (power consumption, water and reagent usage). In Phase I of this project, laboratory and pilot-scale test units were evaluated at various industrial sites in both the coal and mineral industries. Based on promising results obtained from Phase I, full-scale prototypes were purchased and installed by a major U.S. phosphate producer and a large eastern U.S. coal company. The test data obtained from these sites demonstrate that significant performance improvements can be realized through the application of these high-efficiency separators.
Renninger, Heidi J; McCulloh, Katherine A; Phillips, Nathan
2013-02-01
Palms are an important component of tropical ecosystems, living alongside dicotyledonous trees, even though they have a very different growth pattern and vascular system. As monocots, vessels in palms are located within vascular bundles and, without a vascular cambium that many dicotyledonous trees possess, palms cannot add additional vessels to their vascular system as they get older and taller. This means that hydraulic architecture in palms is more predetermined, which may require a highly efficient hydraulic system. This preset nature, along with the decoupling of hydraulic and mechanical functioning to different cell types, may allow palms to have a more efficient hydraulic system than dicotyledonous trees. Therefore, this study seeks to determine the efficiency of the hydraulic system in the palm Iriartea deltoidea (Ruiz & Pav.) and compare this efficiency with other tree forms. We measured cross-sectional areas of roots, stems and fronds as well as leaf areas of I. deltoidea saplings. Likewise, cross-sections were made and vessel diameters and frequencies measured. This allowed for the calculation of theoretical specific conductivity (K(S,calc)), theoretical leaf-specific conductivity (K(L,calc)), and vessel diameter and vessel number ratios between distal and proximal locations in the palms. Iriartea deltoidea palms were found to have the largest, least frequent vessels that diverged most from the square packing limit (maximum number of vessels that fit into a given area) compared with other major tree forms, and they therefore invested the least space and carbon into water transport structures. Likewise, conduits tapered by ∼1/3 between ranks (root, bole and petiole), which represents an efficient ratio with regard to the trade-offs between safety and efficiency of the conducting system. Conduits also exhibited a high conservation of the sum of the conduit radii cubed (Σr(3)) across ranks, thereby approximating Murray's law patterning. Therefore, our
Size dependence of efficiency at maximum power of heat engine
Izumida, Y.
2013-10-01
We perform a molecular dynamics computer simulation of a heat engine model to study how the engine size difference affects its performance. Upon tactically increasing the size of the model anisotropically, we determine that there exists an optimum size at which the model attains the maximum power for the shortest working period. This optimum size locates between the ballistic heat transport region and the diffusive heat transport one. We also study the size dependence of the efficiency at the maximum power. Interestingly, we find that the efficiency at the maximum power around the optimum size attains a value that has been proposed as a universal upper bound, and it even begins to exceed the bound as the size further increases. We explain this behavior of the efficiency at maximum power by using a linear response theory for the heat engine operating under a finite working period, which naturally extends the low-dissipation Carnot cycle model [M. Esposito, R. Kawai, K. Lindenberg, C. Van den Broeck, Phys. Rev. Lett. 105, 150603 (2010)]. The theory also shows that the efficiency at the maximum power under an extreme condition may reach the Carnot efficiency in principle.© EDP Sciences Società Italiana di Fisica Springer-Verlag 2013.
Valve and Manifold considerations for Efficient Digital Hydraulic Machines
Roemer, Daniel Beck; Nørgård, Christian; Bech, Michael Møller;
2016-01-01
This paper seeks to shed light on the topic of design and sizing of switching valves and connecting manifolds found in large digital hydraulic motors, also known commercially as Digital Displacement Motors. These motors promise very high operation efficiencies with broad operation ranges, which set...... valves when considering also the manifold flow losses. A global optimization is conducted by use of the generalized differential evolution 3 algorithm, where the valve diameters, valve stroke lengths, actuator force capabilities and actuator timing signals are used as design variables. The results...
Quantitative measures for assessment of the hydraulic excavator digging efficiency
Dragoslav JANOSEVIC; Rosen MITREV; Boban ANDJELKOVIC; Plamen PETROV
2012-01-01
In this paper,quantitative measures for the assessment of the hydraulic excavator digging efficiency are proposed and developed.The following factors are considered: (a) boundary digging forces allowed for by the stability of an excavator,(b) boundary digging forces enabled by the driving mechanisms of the excavator,(c) factors taking into consideration the digging position in the working range of an excavator,and (d) sign and direction of potential digging resistive force.A corrected digging force is defined and a mathematical model of kinematic chain and drive mechanisms of a five-member excavator configuration was developed comprising: an undercarriage,a rotational platform and an attachment with boom,stick,and bucket.On the basis of the mathematical model of the excavator,software was developed for computation and detailed analysis of the digging forces in the entire workspace of the excavator.By using the developed software,the analysis of boundary digging forces is conducted and the corrected digging force is determined for two models of hydraulic excavators of the same mass (around 17000 kg) with identical kinematic chain parameters but with different parameters of manipulator driving mechanisms.The results of the analysis show that the proposed set of quantitative measures can be used for assessment of the digging efficiency of existing excavator models and to serve as an optimization criterion in the synthesis of manipulator driving mechanisms of new excavator models.
Efficiency at maximum power of thermally coupled heat engines.
Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph
2012-04-01
We study the efficiency at maximum power of two coupled heat engines, using thermoelectric generators (TEGs) as engines. Assuming that the heat and electric charge fluxes in the TEGs are strongly coupled, we simulate numerically the dependence of the behavior of the global system on the electrical load resistance of each generator in order to obtain the working condition that permits maximization of the output power. It turns out that this condition is not unique. We derive a simple analytic expression giving the relation between the electrical load resistance of each generator permitting output power maximization. We then focus on the efficiency at maximum power (EMP) of the whole system to demonstrate that the Curzon-Ahlborn efficiency may not always be recovered: The EMP varies with the specific working conditions of each generator but remains in the range predicted by irreversible thermodynamics theory. We discuss our results in light of nonideal Carnot engine behavior.
Espino, Susana; Schenk, H Jochen
2011-01-01
The maximum specific hydraulic conductivity (k(max)) of a plant sample is a measure of the ability of a plants' vascular system to transport water and dissolved nutrients under optimum conditions. Precise measurements of k(max) are needed in comparative studies of hydraulic conductivity, as well as for measuring the formation and repair of xylem embolisms. Unstable measurements of k(max) are a common problem when measuring woody plant samples and it is commonly observed that k(max) declines from initially high values, especially when positive water pressure is used to flush out embolisms. This study was designed to test five hypotheses that could potentially explain declines in k(max) under positive pressure: (i) non-steady-state flow; (ii) swelling of pectin hydrogels in inter-vessel pit membranes; (iii) nucleation and coalescence of bubbles at constrictions in the xylem; (iv) physiological wounding responses; and (v) passive wounding responses, such as clogging of the xylem by debris. Prehydrated woody stems from Laurus nobilis (Lauraceae) and Encelia farinosa (Asteraceae) collected from plants grown in the Fullerton Arboretum in Southern California, were used to test these hypotheses using a xylem embolism meter (XYL'EM). Treatments included simultaneous measurements of stem inflow and outflow, enzyme inhibitors, stem-debarking, low water temperatures, different water degassing techniques, and varied concentrations of calcium, potassium, magnesium, and copper salts in aqueous measurement solutions. Stable measurements of k(max) were observed at concentrations of calcium, potassium, and magnesium salts high enough to suppress bubble coalescence, as well as with deionized water that was degassed using a membrane contactor under strong vacuum. Bubble formation and coalescence under positive pressure in the xylem therefore appear to be the main cause for declining k(max) values. Our findings suggest that degassing of water is essential for achieving stable and
Valve and Manifold considerations for Efficient Digital Hydraulic Machines
Roemer, Daniel Beck; Nørgård, Christian; Bech, Michael Møller
2016-01-01
This paper seeks to shed light on the topic of design and sizing of switching valves and connecting manifolds found in large digital hydraulic motors, also known commercially as Digital Displacement Motors. These motors promise very high operation efficiencies with broad operation ranges, which set...... strict requirements to the switching valves and the overall manifold design. To investigate this topic, the largest known digital motor (3.5 megawatt) is studied using models and optimization. Based on the limited information available about this motor, a detailed reconstruction of the motor architecture...... valves when considering also the manifold flow losses. A global optimization is conducted by use of the generalized differential evolution 3 algorithm, where the valve diameters, valve stroke lengths, actuator force capabilities and actuator timing signals are used as design variables. The results...
Efficiency at Maximum Power of Low-Dissipation Carnot Engines
Esposito, Massimiliano; Kawai, Ryoichi; Lindenberg, Katja; van den Broeck, Christian
2010-10-01
We study the efficiency at maximum power, η*, of engines performing finite-time Carnot cycles between a hot and a cold reservoir at temperatures Th and Tc, respectively. For engines reaching Carnot efficiency ηC=1-Tc/Th in the reversible limit (long cycle time, zero dissipation), we find in the limit of low dissipation that η* is bounded from above by ηC/(2-ηC) and from below by ηC/2. These bounds are reached when the ratio of the dissipation during the cold and hot isothermal phases tend, respectively, to zero or infinity. For symmetric dissipation (ratio one) the Curzon-Ahlborn efficiency ηCA=1-Tc/Th is recovered.
Efficiency at maximum power of low-dissipation Carnot engines.
Esposito, Massimiliano; Kawai, Ryoichi; Lindenberg, Katja; Van den Broeck, Christian
2010-10-01
We study the efficiency at maximum power, η*, of engines performing finite-time Carnot cycles between a hot and a cold reservoir at temperatures Th and Tc, respectively. For engines reaching Carnot efficiency ηC=1-Tc/Th in the reversible limit (long cycle time, zero dissipation), we find in the limit of low dissipation that η* is bounded from above by ηC/(2-ηC) and from below by ηC/2. These bounds are reached when the ratio of the dissipation during the cold and hot isothermal phases tend, respectively, to zero or infinity. For symmetric dissipation (ratio one) the Curzon-Ahlborn efficiency ηCA=1-√Tc/Th] is recovered.
Efficient maximum likelihood parameterization of continuous-time Markov processes
McGibbon, Robert T
2015-01-01
Continuous-time Markov processes over finite state-spaces are widely used to model dynamical processes in many fields of natural and social science. Here, we introduce an maximum likelihood estimator for constructing such models from data observed at a finite time interval. This estimator is drastically more efficient than prior approaches, enables the calculation of deterministic confidence intervals in all model parameters, and can easily enforce important physical constraints on the models such as detailed balance. We demonstrate and discuss the advantages of these models over existing discrete-time Markov models for the analysis of molecular dynamics simulations.
Efficiency at maximum power of a discrete feedback ratchet
Jarillo, Javier; Tangarife, Tomás; Cao, Francisco J.
2016-01-01
Efficiency at maximum power is found to be of the same order for a feedback ratchet and for its open-loop counterpart. However, feedback increases the output power up to a factor of five. This increase in output power is due to the increase in energy input and the effective entropy reduction obtained as a consequence of feedback. Optimal efficiency at maximum power is reached for time intervals between feedback actions two orders of magnitude smaller than the characteristic time of diffusion over a ratchet period length. The efficiency is computed consistently taking into account the correlation between the control actions. We consider a feedback control protocol for a discrete feedback flashing ratchet, which works against an external load. We maximize the power output optimizing the parameters of the ratchet, the controller, and the external load. The maximum power output is found to be upper bounded, so the attainable extracted power is limited. After, we compute an upper bound for the efficiency of this isothermal feedback ratchet at maximum power output. We make this computation applying recent developments of the thermodynamics of feedback-controlled systems, which give an equation to compute the entropy reduction due to information. However, this equation requires the computation of the probability of each of the possible sequences of the controller's actions. This computation becomes involved when the sequence of the controller's actions is non-Markovian, as is the case in most feedback ratchets. We here introduce an alternative procedure to set strong bounds to the entropy reduction in order to compute its value. In this procedure the bounds are evaluated in a quasi-Markovian limit, which emerge when there are big differences between the stationary probabilities of the system states. These big differences are an effect of the potential strength, which minimizes the departures from the Markovianicity of the sequence of control actions, allowing also to
AN EFFICIENT APPROXIMATE MAXIMUM LIKELIHOOD SIGNAL DETECTION FOR MIMO SYSTEMS
Cao Xuehong
2007-01-01
This paper proposes an efficient approximate Maximum Likelihood (ML) detection method for Multiple-Input Multiple-Output (MIMO) systems, which searches local area instead of exhaustive search and selects valid search points in each transmit antenna signal constellation instead of all hyperplane. Both of the selection and search complexity can be reduced significantly. The method performs the tradeoff between computational complexity and system performance by adjusting the neighborhood size to select the valid search points. Simulation results show that the performance is comparable to that of the ML detection while the complexity is only as the small fraction of ML.
In-Plant Testing of High-Efficiency Hydraulic Separators
G. H. Luttrell; R. Q. Honaker; R. C. Bratton; T. C. Westerfield; J. N. Kohmuench
2004-07-20
The mineral processing industry has commonly utilized hydraulic separators throughout history for classification and gravity concentration of various minerals. More commonly referred to as hindered-bed or fluidized-bed separators, these units make use of differential particle settling rates to segregate particles according to shape, size, and/or density. As with any equipment, there are inefficiencies associated with its operation, which prompted an industry driven research program to further evaluate two novel high-efficiency hindered bed separators. These units, which are commercially called the CrossFlow separator and HydroFloat separator, have the potential to improve performance (separation efficiency and throughput) and reduce operating costs (power consumption, water and reagent usage). This report describes the results of Phase I activities (laboratory and pilot-scale tests) conducted with the CrossFlow and HydroFloat separators at several locations in the minerals and coal industries. Details of the testing programs (equipment setup, shakedown testing and detailed testing) associated with four coal plants and two phosphate plants are summarized in this work. In most of these applications, the high-efficiency units proved to provide a higher quality product at reduced costs when compared against the performance of conventional separators. Based on promising results obtained from Phase I, full-scale prototypes will be purchased by several mining companies for use in Phase II of this project. Two of the prototype units, which will be constructed by Eriez Manufacturing, are expected to be installed by a major U.S. phosphate producer and a large eastern U.S. coal company. Negotiations are also underway to purchase and install additional prototype units by a mineral sands producer and a second phosphate producer. The data obtained from the full-scale evaluations will be used to further promote commercialization and industrial applications of these innovative
On a robust and efficient maximum depth estimator
ZUO YiJun; LAI ShaoYong
2009-01-01
The best breakdown point robustness is one of the most outstanding features of the univariate median. For this robustness property, the median, however, has to pay the price of a low efficiency at normal and other light-tailed models. Affine equivariant multivariate analogues of the univariate median with high breakdown points were constructed in the past two decades. For the high breakdown robustness, most of them also have to sacrifice their efficiency at normal and other models,nevertheless. The affine equivariant maximum depth estimator proposed and studied in this paper turns out to be an exception. Like the univariate median, it also possesses a highest breakdown point among all its multivariate competitors. Unlike the univariate median, it is also highly efficient relative to the sample mean at normal and various other distributions, overcoming the vital low-efficiency shortcoming of the univariate and other multivariate generalized medians. The paper also studies the asymptotics of the estimator and establishes its limit distribution without symmetry and other strong assumptions that are typically imposed on the underlying distribution.
Grinding efficiency improvement of hydraulic cylinders parts for mining equipment
Aleksandr Korotkov; Vitaliy Korotkov; Leonid Mametyev; Lidia Korotkova; Tatiana Terjaeva
2017-01-01
The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms...
Efficiency at maximum power of a chemical engine.
Hooyberghs, Hans; Cleuren, Bart; Salazar, Alberto; Indekeu, Joseph O; Van den Broeck, Christian
2013-10-01
A cyclically operating chemical engine is considered that converts chemical energy into mechanical work. The working fluid is a gas of finite-sized spherical particles interacting through elastic hard collisions. For a generic transport law for particle uptake and release, the efficiency at maximum power η(mp) [corrected] takes the form 1/2+cΔμ+O(Δμ(2)), with 1∕2 a universal constant and Δμ the chemical potential difference between the particle reservoirs. The linear coefficient c is zero for engines featuring a so-called left/right symmetry or particle fluxes that are antisymmetric in the applied chemical potential difference. Remarkably, the leading constant in η(mp) [corrected] is non-universal with respect to an exceptional modification of the transport law. For a nonlinear transport model, we obtain η(mp) = 1/(θ + 1) [corrected], with θ > 0 the power of Δμ in the transport equation.
Efficiency at maximum power of a chemical engine
Hooyberghs, Hans; Salazar, Alberto; Indekeu, Joseph O; Broeck, Christian Van den
2013-01-01
A cyclically operating chemical engine is considered that converts chemical energy into mechanical work. The working fluid is a gas of finite-sized spherical particles interacting through elastic hard collisions. For a generic transport law for particle uptake and release, the efficiency at maximum power $\\eta$ takes the form 1/2+c\\Delta \\mu + O(\\Delta \\mu^2), with 1/2 a universal constant and $\\Delta \\mu$ the chemical potential difference between the particle reservoirs. The linear coefficient c is zero for engines featuring a so-called left/right symmetry or particle fluxes that are antisymmetric in the applied chemical potential difference. Remarkably, the leading constant in $\\eta$ is non-universal with respect to an exceptional modification of the transport law. For a nonlinear transport model we obtain \\eta = 1/(\\theta +1), with \\theta >0 the power of $\\Delta \\mu$ in the transport equation
ENERGY EFFICIENCY OF DIESEL LOCOMOTIVE HYDRAULIC TRANSMISSION TESTS AT LOCOMOTIVE REPAIR PLANT
B. E. Bodnar
2015-10-01
Full Text Available Purpose. In difficult economic conditions, cost reduction of electricity consumption for the needs of production is an urgent task for the country’s industrial enterprises. Technical specifications of enterprises, which repair diesel locomotive hydraulic transmission, recommend conducting a certain amount of evaluation and regulatory tests to monitor their condition after repair. Experience shows that a significant portion of hydraulic transmission defects is revealed by bench tests. The advantages of bench tests include the ability to detect defects after repair, ease of maintenance of the hydraulic transmission and relatively low labour intensity for eliminating defects. The quality of these tests results in the transmission resource and its efficiency. Improvement of the technology of plant post-repairs hydraulic tests in order to reduce electricity consumption while testing. Methodology. The possible options for hydraulic transmission test bench improvement were analysed. There was proposed an energy efficiency method for diesel locomotive hydraulic transmission testing in locomotive repair plant environment. This is achieved by installing additional drive motor which receives power from the load generator. Findings. Based on the conducted analysis the necessity of improving the plant stand testing of hydraulic transmission was proved. The variants of the stand modernization were examined. The test stand modernization analysis was conducted. Originality. The possibility of using electric power load generator to power the stand electric drive motor or the additional drive motor was theoretically substantiated. Practical value. A variant of hydraulic transmission test stand based on the mutual load method was proposed. Using this method increases the hydraulic transmission load range and power consumption by stand remains unchanged. The additional drive motor will increase the speed of the input shaft that in its turn wil allow testing in
Grinding efficiency improvement of hydraulic cylinders parts for mining equipment
Korotkov Aleksandr
2017-01-01
Full Text Available The aim of the article is to find out ways to improve parts treatment and components of mining equipment on the example of hydraulic cylinders parts, used as pillars for mine roof supports, and other actuator mechanisms. In the course of the research work methods of machine retaining devices design were used, the scientific approaches for the selection of progressive grinding schemes were applied; theoretical and practical experience in the design and production of new constructions of grinding tools was used. As a result of this work it became possible to create a progressive construction of a machine retaining device for grinding of large parts of hydraulic cylinders, to apply an effective scheme of rotary abrasive treatment, to create and implement new design of grinding tools by means of grains with controllable shape and orientation. Implementation of the results obtained in practice will improve the quality and performance of repairing and manufacturing of mining equipment.
Maximum efficiency of low-dissipation heat engines at arbitrary power
Holubec, Viktor; Ryabov, Artem
2016-07-01
We investigate maximum efficiency at a given power for low-dissipation heat engines. Close to maximum power, the maximum gain in efficiency scales as a square root of relative loss in power and this scaling is universal for a broad class of systems. For low-dissipation engines, we calculate the maximum gain in efficiency for an arbitrary fixed power. We show that engines working close to maximum power can operate at considerably larger efficiency compared to the efficiency at maximum power. Furthermore, we introduce universal bounds on maximum efficiency at a given power for low-dissipation heat engines. These bounds represent direct generalization of the bounds on efficiency at maximum power obtained by Esposito et al (2010 Phys. Rev. Lett. 105 150603). We derive the bounds analytically in the regime close to maximum power and for small power values. For the intermediate regime we present strong numerical evidence for the validity of the bounds.
[Impacts of the hydraulic characteristics of pilot clearwell on chlorine disinfection efficiency].
Liu, Qing; Liu, Wen-Jun; Gao, Jing-Wei; Zhang, Su-Xia
2009-09-15
A pilot clearwell was used to simulate the chlorine disinfection process with the Bacillus subtilis spores as the target microbe. The effluent of the activated carbon filter tank was radiated by low pressure UV lamp and then used as the influent the pilot clearwell. The impacts of hydraulic characteristics of pilot clearwell on disinfection efficiency of Bacillus subtilis spores was studied under different hydraulic characteristics which was changed by the number of the baffles. Under the conditions of this experiment, the inactivation coefficients of Bacillus subtilis spores with NaC10 as disinfectant which were calculated by Ct10 value were almost same under different hydraulic characteristics, but the inactivation coefficients which were calculated by CT value were very different under different hydraulic characteristics. This verified that it was more reasonable to evaluate the disinfection efficiency by Ct10 value than CT value. When Ct10 value was in the range of 100 - 300 mg x min/L, the inactivation coefficient of Bacillus subtilis spores with NaClO as disinfectant was 0.001 6 L(mg x min), which highly coincided with others' results. When CT value was in the range of 100 - 700 mg x min/L, under the same CT value, the disinfection efficiency of target microbe would be notably enhanced by increasing the number of baffles which would improve the hydraulic characteristics. So the results verified that the disinfection efficiency could be enhanced by improving the hydraulic characteristics of the clearwell.
Is rootstock-induced dwarfing in olive an effect of reduced plant hydraulic efficiency?
Nardini, Andrea; Gascó, Antonio; Raimondo, Fabio; Gortan, Emmanuelle; Lo Gullo, Maria A; Caruso, Tiziano; Salleo, Sebastiano
2006-09-01
We investigated the hydraulic architecture of young olive trees either self-rooted or grafted on rootstocks with contrasting size-controlling potential. Clones of Olea europea L. (Olive) cv 'Leccino' inducing vigorous scion growth (Leccino 'Minerva', LM) or scion dwarfing (Leccino 'Dwarf', LD) were studied in different scion/rootstock combinations (LD, LM, LD/LD, LM/LM, LD/LM and LM/LD). Shoots growing on LD root systems developed about 50% less leaf surface area than shoots growing on LM root systems. Root systems accounted for 60-70% of plant hydraulic resistance (R), whereas hydraulic resistance of the graft union was negligible. Hydraulic conductance (K = 1/R) of LD root systems was up to 2.5 times less than that of LM root systems. Total leaf surface area (A(L)) was closely and positively related to root hydraulic conductance so that whole-plant hydraulic conductance scaled by A(L) did not differ between experimental groups. Accordingly, maximum transpiration rate and minimum leaf water potential did not differ significantly among experimental groups. We conclude that reduced root hydraulic conductance may explain rootstock-induced dwarfing in olive.
Maximum herd efficiency in meat production I. Optima for slaughter ...
changes in product value are important, it is easy to join them to herd cost efficiency for ... should be evaluated in terms of total herd or life cycle effi- ciency, and not only for a ..... The decline of herd efficiency with increases in b in. Table 2 is in ...
Chen, Jincan; Yan, Zijun; Wu, Liqing
1996-06-01
Considering a thermoelectric generator as a heat engine cycle, the general differential equations of the temperature field inside thermoelectric elements are established by means of nonequilibrium thermodynamics. These equations are used to study the influence of heat leak, Joule's heat, and Thomson heat on the performance of the thermoelectric generator. New expressions are derived for the power output and the efficiency of the thermoelectric generator. The maximum power output is calculated and the optimal matching condition of load is determined. The maximum efficiency is discussed by a representative numerical example. The aim of this research is to provide some novel conclusions and redress some errors existing in a related investigation.
An efficient approach to imaging underground hydraulic networks
Kumar, Mohi
2012-07-01
To better locate natural resources, treat pollution, and monitor underground networks associated with geothermal plants, nuclear waste repositories, and carbon dioxide sequestration sites, scientists need to be able to accurately characterize and image fluid seepage pathways below ground. With these images, scientists can gain knowledge of soil moisture content, the porosity of geologic formations, concentrations and locations of dissolved pollutants, and the locations of oil fields or buried liquid contaminants. Creating images of the unknown hydraulic environments underfoot is a difficult task that has typically relied on broad extrapolations from characteristics and tests of rock units penetrated by sparsely positioned boreholes. Such methods, however, cannot identify small-scale features and are very expensive to reproduce over a broad area. Further, the techniques through which information is extrapolated rely on clunky and mathematically complex statistical approaches requiring large amounts of computational power.
Maximum herd efficiency in meat production II. The influence of ...
efficiency involves reproduction and replacement rates, early fertility, and degree of fertility at first mating. .... For cattle and sheep, an estimate of the effect of early breeding ..... Genetic correlations among sex-limited traits in beef cattle. :. Anim.
Thermal properties for the thermal-hydraulics analyses of the BR2 maximum nominal heat flux.
Dionne, B.; Kim, Y. S.; Hofman, G. L. (Nuclear Engineering Division)
2011-05-23
This memo describes the assumptions and references used in determining the thermal properties for the various materials used in the BR2 HEU (93% enriched in {sup 235}U) to LEU (19.75% enriched in {sup 235}U) conversion feasibility analysis. More specifically, this memo focuses on the materials contained within the pressure vessel (PV), i.e., the materials that are most relevant to the study of impact of the change of fuel from HEU to LEU. This section is regrouping all of the thermal property tables. Section 2 provides a summary of the thermal properties in form of tables while the following sections present the justification of these values. Section 3 presents a brief background on the approach used to evaluate the thermal properties of the dispersion fuel meat and specific heat capacity. Sections 4 to 7 discuss the material properties for the following materials: (i) aluminum, (ii) dispersion fuel meat (UAlx-Al and U-7Mo-Al), (iii) beryllium, and (iv) stainless steel. Section 8 discusses the impact of irradiation on material properties. Section 9 summarizes the material properties for typical operating temperatures. Appendix A elaborates on how to calculate dispersed phase's volume fraction. Appendix B shows the evolution of the BR2 maximum heat flux with burnup.
DETERMINATION OF HYDRAULIC TURBINE EFFICIENCY BY MEANS OF THE CURRENT METER METHOD
PURECE C.
2016-12-01
Full Text Available The paper presents methodology used for determining the efficiency of a low head Kaplan hydraulic turbine with short converging intake. The measurement method used was the current meters method, the only measurement method recommended by the IEC 41standard for flow measurement in this case. The paper also presents the methodology used for measuring the flow by means of the current meters method and the various procedures for calculating the flow. In the last part the paper presents the flow measurements carried out on the Fughiu HPP hydraulic turbines for determining the actual operating efficiency.
Westhoff, Martijn; Zehe, Erwin; Erpicum, Sébastien; Archambeau, Pierre; Pirotton, Michel; Dewals, Benjamin
2015-04-01
The Maximum Entropy Production (MEP) principle is a conjecture assuming that a medium is organized in such a way that maximum power is subtracted from a gradient driving a flux (with power being a flux times its driving gradient). This maximum power is also known as the Carnot limit. It has already been shown that the atmosphere operates close to this Carnot limit when it comes to heat transport from the Equator to the poles, or vertically, from the surface to the atmospheric boundary layer. To reach this state close to the Carnot limit, the effective thermal conductivity of the atmosphere is adapted by the creation of convection cells (e.g. wind). The aim of this study is to test if the soil's effective hydraulic conductivity also adapts itself in such a way that it operates close to the Carnot limit. The big difference between atmosphere and soil is the way of adaptation of its resistance. The soil's hydraulic conductivity is either changed by weathering processes, which is a very slow process, or by creation of preferential flow paths. In this study the latter process is simulated in a lab experiment, where we focus on the preferential flow paths created by piping. Piping is the process of backwards erosion of sand particles subject to a large pressure gradient. Since this is a relatively fast process, it is suitable for being tested in the lab. In the lab setup a horizontal sand bed connects two reservoirs that both drain freely at a level high enough to keep the sand bed always saturated. By adding water to only one reservoir, a horizontal pressure gradient is maintained. If the flow resistance is small, a large gradient develops, leading to the effect of piping. When pipes are being formed, the effective flow resistance decreases; the flow through the sand bed increases and the pressure gradient decreases. At a certain point, the flow velocity is small enough to stop the pipes from growing any further. In this steady state, the effective flow resistance of
Ouerdane, H.; Apertet, Y.; Goupil, C.; Lecoeur, Ph.
2015-07-01
Classical equilibrium thermodynamics is a theory of principles, which was built from empirical knowledge and debates on the nature and the use of heat as a means to produce motive power. By the beginning of the 20th century, the principles of thermodynamics were summarized into the so-called four laws, which were, as it turns out, definitive negative answers to the doomed quests for perpetual motion machines. As a matter of fact, one result of Sadi Carnot's work was precisely that the heat-to-work conversion process is fundamentally limited; as such, it is considered as a first version of the second law of thermodynamics. Although it was derived from Carnot's unrealistic model, the upper bound on the thermodynamic conversion efficiency, known as the Carnot efficiency, became a paradigm as the next target after the failure of the perpetual motion ideal. In the 1950's, Jacques Yvon published a conference paper containing the necessary ingredients for a new class of models, and even a formula, not so different from that of Carnot's efficiency, which later would become the new efficiency reference. Yvon's first analysis of a model of engine producing power, connected to heat source and sink through heat exchangers, went fairly unnoticed for twenty years, until Frank Curzon and Boye Ahlborn published their pedagogical paper about the effect of finite heat transfer on output power limitation and their derivation of the efficiency at maximum power, now mostly known as the Curzon-Ahlborn (CA) efficiency. The notion of finite rate explicitly introduced time in thermodynamics, and its significance cannot be overlooked as shown by the wealth of works devoted to what is now known as finite-time thermodynamics since the end of the 1970's. The favorable comparison of the CA efficiency to actual values led many to consider it as a universal upper bound for real heat engines, but things are not so straightforward that a simple formula may account for a variety of situations. The
Development of a Test Apparatus for Measurement of Hydraulic Fluid Efficiency
Matt Jackson; Brian Koehler
2011-01-01
With increasing demand for nonrenewable resources,energy conservation is critical.Efficiency gains allow more work to be performed while maintaining or even decreasing the energy expended in the process.Reducing the energy consumed by a system results in favorable economic and environmental impact.An apparatus has been developed to measure hydraulic fluid efficiency in a stationary application.The system can be used to develop more efficient fluids,leading to increased work output or decreased energy consumption.
Lemofouet, Sylvain; Rufer, Alfred
This paper presents a hybrid energy storage system mainly based on Compressed Air, where the storage and withdrawal of energy are done within maximum efficiency conditions. As these maximum efficiency conditions impose the level of converted power, an intermittent time-modulated operation mode is applied to the thermodynamic converter to obtain a variable converted power. A smoothly variable output power is achieved with the help of a supercapacitive auxiliary storage device used as a filter. The paper describes the concept of the system, the power-electronic interfaces and especially the Maximum Efficiency Point Tracking (MEPT) algorithm and the strategy used to vary the output power. In addition, the paper introduces more efficient hybrid storage systems where the volumetric air machine is replaced by an oil-hydraulics and pneumatics converter, used under isothermal conditions. Practical results are also presented, recorded from a low-power air motor coupled to a small DC generator, as well as from a first prototype of the hydro-pneumatic system. Some economical considerations are also made, through a comparative cost evaluation of the presented hydro-pneumatic systems and a lead acid batteries system, in the context of a stand alone photovoltaic home application. This evaluation confirms the cost effectiveness of the presented hybrid storage systems.
Elevational trends in hydraulic efficiency and safety of Pinus cembra roots.
Losso, Adriano; Nardini, Andrea; Nolf, Markus; Mayr, Stefan
2016-04-01
In alpine regions, elevational gradients in environmental parameters are reflected by structural and functional changes in plant traits. Elevational changes in plant water relations have also been demonstrated, but comparable information on root hydraulics is generally lacking. We analyzed the hydraulic efficiency (specific hydraulic conductivity k s, entire root system conductance K R) and vulnerability to drought-induced embolism (water potential at 50 % loss of conductivity Ψ 50) of the roots of Pinus cembra trees growing along an elevational transect of 600 m. Hydraulic parameters of the roots were compared with those of the stem and related to anatomical traits {mean conduit diameter (d), wall reinforcement [(t/b)(2)]}. We hypothesized that temperature-related restrictions in root function would cause a progressive limitation of hydraulic efficiency and safety with increasing elevation. We found that both root k s and K R decreased from low (1600 m a.s.l.: k s 5.6 ± 0.7 kg m(-1) s(-1) MPa(-1), K R 0.049 ± 0.005 kg m(-2) s (-1) MPa(-1)) to high elevation (2100 m a.s.l.: k s 4.2 ± 0.6 kg m(-1) s(-1) MPa(-1), K R 0.035 ± 0.006 kg m(-2) s(-1) MPa(-1)), with small trees showing higher K R than large trees. k s was higher in roots than in stems (0.5 ± 0.05 kg m(-1)s(-1)MPa(-1)). Ψ 50 values were similar across elevations and overall less negative in roots (Ψ 50 -3.6 ± 0.1 MPa) than in stems (Ψ 50 -3.9 ± 0.1 MPa). In roots, large-diameter tracheids were lacking at high elevation and (t/b)(2) increased, while d did not change. The elevational decrease in root hydraulic efficiency reflects a limitation in timberline tree hydraulics. In contrast, hydraulic safety was similar across elevations, indicating that avoidance of hydraulic failure is important for timberline trees. As hydraulic patterns can only partly be explained by the anatomical parameters studied, limitations and/or adaptations at the pit level are likely.
On the maximum efficiency of realistic heat engines
Miranda, E N
2012-01-01
In 1975, Courzon and Ahlborn studied a Carnot engine with thermal losses and got an expression for its efficiency that described better the performance of actual heat machines than the traditional result due to Carnot. In their original derivation, time appears explicitly and this is disappointing in the framework of classical thermodynamics. In this note a derivation is given without any explicit reference to time.
Study on maximum efficiency control strategy for induction motor
无
2007-01-01
Two new techniques for effficiency-optimization control (EOC) of induction motor drives were proposed. The first method combined Loss Model and "golden section technique", which was faster than the available methods. Secondly, the low-frequency ripple torque due to decrease of rotor flux was compensated in a feedforward manner. If load torque or speed command changed, the efficiency search algorithm would be abandoned and the rated flux would be established to get the best transient response. The close agreement between the simulation and the experimental results confirmed the validity and usefulness of the proposed techniques.
Haseli, Y
2016-05-01
The objective of this study is to investigate the thermal efficiency and power production of typical models of endoreversible heat engines at the regime of minimum entropy generation rate. The study considers the Curzon-Ahlborn engine, the Novikov's engine, and the Carnot vapor cycle. The operational regimes at maximum thermal efficiency, maximum power output and minimum entropy production rate are compared for each of these engines. The results reveal that in an endoreversible heat engine, a reduction in entropy production corresponds to an increase in thermal efficiency. The three criteria of minimum entropy production, the maximum thermal efficiency, and the maximum power may become equivalent at the condition of fixed heat input.
Lohse, Harald; Weber, Juergen [Technische Univ. Dresden (Germany). Inst. fuer Fluidtechnik (IFD)
2012-10-08
Reliable data are missing in the evaluation of the energy efficiency of hydraulic deep-drawing presses. Now methods for monitoring of consumption and loss data were defined and tested. Based on these methods, simulation models for the evaluation of energy saving potentials were developed.
Efficiency at maximum power and efficiency fluctuations in a linear Brownian heat-engine model
Park, Jong-Min; Chun, Hyun-Myung; Noh, Jae Dong
2016-07-01
We investigate the stochastic thermodynamics of a two-particle Langevin system. Each particle is in contact with a heat bath at different temperatures T1 and T2 (autonomous heat engine performing work against the external driving force. Linearity of the system enables us to examine thermodynamic properties of the engine analytically. We find that the efficiency of the engine at maximum power ηM P is given by ηM P=1 -√{T2/T1 } . This universal form has been known as a characteristic of endoreversible heat engines. Our result extends the universal behavior of ηM P to nonendoreversible engines. We also obtain the large deviation function of the probability distribution for the stochastic efficiency in the overdamped limit. The large deviation function takes the minimum value at macroscopic efficiency η =η ¯ and increases monotonically until it reaches plateaus when η ≤ηL and η ≥ηR with model-dependent parameters ηR and ηL.
Ocheltree, Troy W; Nippert, Jesse B; Prasad, P V Vara
2016-04-01
A common theme in plant physiological research is the trade-off between stress tolerance and growth; an example of this trade-off at the tissue level is the safety vs efficiency hypothesis, which suggests that plants with the greatest resistance to hydraulic failure should have low maximum hydraulic conductance. Here, we quantified the leaf-level drought tolerance of nine C4 grasses as the leaf water potential at which plants lost 50% (P50 × RR ) of maximum leaf hydraulic conductance (Ksat ), and compared this trait with other leaf-level and whole-plant functions. We found a clear trade-off between Ksat and P50 × RR when Ksat was normalized by leaf area and mass (P = 0.05 and 0.01, respectively). However, no trade-off existed between P50 × RR and gas-exchange rates; rather, there was a positive relationship between P50 × RR and photosynthesis (P = 0.08). P50 × RR was not correlated with species distributions based on precipitation (P = 0.70), but was correlated with temperature during the wettest quarter of the year (P hydraulic system of grass leaves, which can be decoupled from other leaf-level functions. The unique physiology of C4 plants and adaptations to pulse-driven systems may provide mechanisms that could decouple hydraulic conductance from other plant functions.
Larsen, Ulrik; Pierobon, Leonardo; Wronski, Jorrit;
2014-01-01
to power. In this study we propose four linear regression models to predict the maximum obtainable thermal efficiency for simple and recuperated ORCs. A previously derived methodology is able to determine the maximum thermal efficiency among many combinations of fluids and processes, given the boundary...
Quan, H T
2014-06-01
We study the maximum efficiency of a heat engine based on a small system. It is revealed that due to the finiteness of the system, irreversibility may arise when the working substance contacts with a heat reservoir. As a result, there is a working-substance-dependent correction to the Carnot efficiency. We derive a general and simple expression for the maximum efficiency of a Carnot cycle heat engine in terms of the relative entropy. This maximum efficiency approaches the Carnot efficiency asymptotically when the size of the working substance increases to the thermodynamic limit. Our study extends Carnot's result of the maximum efficiency to an arbitrary working substance and elucidates the subtlety of thermodynamic laws in small systems.
Hermann, M. [Fraunhofer Inst. for Solar Energy Systems, Freiburg (Germany)
2004-07-01
The energy efficiency of heat exchangers such as solar absorbers is determined both by their thermal efficiency - evaluated by the collector efficiency factor F' - and the primary energy which is needed to drive the pump transporting the fluid. The former is strongly influenced by the uniformity of the volume flow whereas the latter also depends on the pressure drop in the fluid channels. Thus, in order to obtain a high energy efficiency, it is necessary to ensure a uniform flow distribution with low pressure drop. However, conventional hydraulic structures often show a high pressure drop (serial flow) or a non-uniform flow distribution (parallel flow). In contrast to these channel designs, many natural structures are built of multiple branched channels (''fractals''). The aim of a current research work, which is funded by the German Federal Environmental Foundation (DBU), is to transfer those principles of fluid channel design to technical applications (bionic approach) and compare the structures with conventional ones. This paper describes how fractal hydraulic structures are generated and assessed using hydraulic and thermal simulations. Flow experiments as well as thermography with an absorber model are shown. Furthermore, investigations of flow phenomena using Computational Fluid Dynamics (CFD) are presented. (orig.)
David S. Schechter
2005-04-27
This report describes the work performed during the fourth year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificially fractured cores (AFCs) and X-ray CT scanner to examine the physical mechanisms of bypassing in hydraulically fractured reservoirs (HFR) and naturally fractured reservoirs (NFR) that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. In Chapter 1, we worked with DOE-RMOTC to investigate fracture properties in the Tensleep Formation at Teapot Dome Naval Reserve as part of their CO{sub 2} sequestration project. In Chapter 2, we continue our investigation to determine the primary oil recovery mechanism in a short vertically fractured core. Finally in Chapter 3, we report our numerical modeling efforts to develop compositional simulator with irregular grid blocks.
López, Rosana; López de Heredia, Unai; Collada, Carmen; Cano, Francisco Javier; Emerson, Brent C; Cochard, Hervé; Gil, Luis
2013-06-01
It is widely accepted that hydraulic failure due to xylem embolism is a key factor contributing to drought-induced mortality in trees. In the present study, an attempt is made to disentangle phenotypic plasticity from genetic variation in hydraulic traits across the entire distribution area of a tree species to detect adaptation to local environments. A series of traits related to hydraulics (vulnerability to cavitation and hydraulic conductivity in branches), growth performance and leaf mass per area were assessed in eight Pinus canariensis populations growing in two common gardens under contrasting environments. In addition, the neutral genetic variability (FST) and the genetic differentiation of phenotypic variation (QST) were compared in order to identify the evolutionary forces acting on these traits. The variability for hydraulic traits was largely due to phenotypic plasticity. Nevertheless, the vulnerability to cavitation displayed a significant genetic variability (approx. 5 % of the explained variation), and a significant genetic × environment interaction (between 5 and 19 % of the explained variation). The strong correlation between vulnerability to cavitation and survival in the xeric common garden (r = -0·81; P xylem safety and efficiency was detected. QST of parameters of the vulnerability curve (0·365 for P50 and the slope of the vulnerability curve and 0·452 for P88) differed substantially from FST (0·091), indicating divergent selection. In contrast, genetic drift alone was found to be sufficient to explain patterns of differentiation for xylem efficiency and growth. The ability of P. canariensis to inhabit a wide range of ecosystems seemed to be associated with high phenotypic plasticity and some degree of local adaptations of xylem and leaf traits. Resistance to cavitation conferred adaptive potential for this species to adapt successfully to xeric conditions.
Y. Haseli
2016-05-01
Full Text Available The objective of this study is to investigate the thermal efficiency and power production of typical models of endoreversible heat engines at the regime of minimum entropy generation rate. The study considers the Curzon-Ahlborn engine, the Novikov’s engine, and the Carnot vapor cycle. The operational regimes at maximum thermal efficiency, maximum power output and minimum entropy production rate are compared for each of these engines. The results reveal that in an endoreversible heat engine, a reduction in entropy production corresponds to an increase in thermal efficiency. The three criteria of minimum entropy production, the maximum thermal efficiency, and the maximum power may become equivalent at the condition of fixed heat input.
Recent advance on the efficiency at maximum power of heat engines
Tu Zhan-Chun
2012-01-01
This review reports several key advances on the theoretical investigations of efficiency at maximum power of heat engines in the past five years.The analytical results of efficiency at maximum power for the Curzon-Ahlborn heat engine,the stochastic heat engine constructed from a Brownian particle,and Feynman's ratchet as a heat engine are presented.It is found that:the efficiency at maximum power exhibits universal behavior at small relative temperature differences; the lower and the upper bounds might exist under quite general conditions; and the problem of efficiency at maximum power comes down to seeking for the minimum irreversible entropy production in each finite-time isothermal process for a given time.
Abhijit Sinha
2014-01-01
Full Text Available A comparative analysis on thermodynamic efficiency based on maximum power & power density conditions have been performed for a solar-driven Carnot heat engine with internal irreversibility. In this analysis, the heat transfer from the hot reservoir is to be in the radiation mode and the heat transfer to the cold reservoir is to be in the convection mode. The thermodynamic efficiency function, power & power density functions have been derived and maximization of the power functions have been performed for various design parameters. From the optimum conditions, the thermal efficiencies at maximum power and power densities have been obtained. The effects of internal irreversibility, extreme temperature ratios & specific engine size in area ratio between the hot & cold reservoirs as various design parameters on thermodynamic efficiencies have been investigated for both the conditions. The efficiencies have been compared with Curzon-Ahlborn & Carnot efficiencies respectively.The analysis showed that the efficiency at maximum power output is greater than the efficiency at maximum power density. And the efficiencies can be greater than the Curzon- Ahlborn`s efficiency only for low values of design parameters.
Efficiency at maximum power for an Otto engine with ideal feedback
Wang, Honghui; He, Jizhou; Wang, Jianhui; Wu, Zhaoqi
2016-10-01
We propose an Otto heat engine that undergoes processes involving a special class of feedback and analyze theoretically its response. We use stochastic thermodynamics to determine the performance characteristics of the heat engine and indicate the possibility that its maximum efficiency can surpass the Carnot value. The analytical expression for efficiency at maximum power, including the effects resulting from feedback, reduces to that previously derived based on an engine without feedback.
The maximum efficiency of nano heat engines depends on more than temperature
Woods, Mischa; Ng, Nelly; Wehner, Stephanie
Sadi Carnot's theorem regarding the maximum efficiency of heat engines is considered to be of fundamental importance in the theory of heat engines and thermodynamics. Here, we show that at the nano and quantum scale, this law needs to be revised in the sense that more information about the bath other than its temperature is required to decide whether maximum efficiency can be achieved. In particular, we derive new fundamental limitations of the efficiency of heat engines at the nano and quantum scale that show that the Carnot efficiency can only be achieved under special circumstances, and we derive a new maximum efficiency for others. A preprint can be found here arXiv:1506.02322 [quant-ph] Singapore's MOE Tier 3A Grant & STW, Netherlands.
Neuville, Amélie; Schmittbuhl, Jean; 10.1111/j.1365-246X.2011.05126.x
2011-01-01
Natural open joints in rocks commonly present multi-scale self-affine apertures. This geometrical complexity affects fluid transport and heat exchange between the flow- ing fluid and the surrounding rock. In particular, long range correlations of self-affine apertures induce strong channeling of the flow which influences both mass and heat advection. A key question is to find a geometrical model of the complex aperture that describes at best the macroscopic properties (hydraulic conductivity, heat exchange) with the smallest number of parameters. Solving numerically the Stokes and heat equa- tions with a lubrication approximation, we show that a low pass filtering of the aperture geometry provides efficient estimates of the effective hydraulic and thermal properties (apertures). A detailed study of the influence of the bandwidth of the lowpass filtering on these transport properties is also performed. For instance, keeping the information of amplitude only of the largest Fourier length scales allows us to rea...
Systematic measurement of maximum efficiencies and detuning lengths at the JAERI free-electron laser
Nishimori, N; Nagai, R; Minehara, E J
2002-01-01
We made a systematic measurement of efficiency detuning curves at several gain and loss parameters. The absolute detuning length (delta L) of an optical cavity was measured within an accuracy of 0.1 mu m around the maximum efficiency by a pulse-stacking method using an external laser. The FEL gain was controlled by the undulator gap instead of bunch charge, because we can change the gain rapidly while maintaining constant electron bunch conditions. For the high-gain and low-loss regions, the maximum efficiency is obtained at delta L=0 mu m and is larger than the value derived from the theoretical scaling law in the superradiant regime, while for the low-gain region the maximum efficiency is obtained for delta L shorter than 0 mu m and is similar to the scaling law.
An Efficient Algorithm for Maximum-Entropy Extension of Block-Circulant Covariance Matrices
Carli, Francesca P; Pavon, Michele; Picci, Giorgio
2011-01-01
This paper deals with maximum entropy completion of partially specified block-circulant matrices. Since positive definite symmetric circulants happen to be covariance matrices of stationary periodic processes, in particular of stationary reciprocal processes, this problem has applications in signal processing, in particular to image modeling. Maximum entropy completion is strictly related to maximum likelihood estimation subject to certain conditional independence constraints. The maximum entropy completion problem for block-circulant matrices is a nonlinear problem which has recently been solved by the authors, although leaving open the problem of an efficient computation of the solution. The main contribution of this paper is to provide an efficient algorithm for computing the solution. Simulation shows that our iterative scheme outperforms various existing approaches, especially for large dimensional problems. A necessary and sufficient condition for the existence of a positive definite circulant completio...
West, Anthony C. F.; Novakowski, Kent S.; Gazor, Saeed
2006-06-01
We propose a new method to estimate the transmissivities of bedrock fractures from transmissivities measured in intervals of fixed length along a borehole. We define the scale of a fracture set by the inverse of the density of the Poisson point process assumed to represent their locations along the borehole wall, and we assume a lognormal distribution for their transmissivities. The parameters of the latter distribution are estimated by maximizing the likelihood of a left-censored subset of the data where the degree of censorship depends on the scale of the considered fracture set. We applied the method to sets of interval transmissivities simulated by summing random fracture transmissivities drawn from a specified population. We found the estimated distributions compared well to the transmissivity distributions of similarly scaled subsets of the most transmissive fractures from among the specified population. Estimation accuracy was most sensitive to the variance in the transmissivities of the fracture population. Using the proposed method, we estimated the transmissivities of fractures at increasing scale from hydraulic test data collected at a fixed scale in Smithville, Ontario, Canada. This is an important advancement since the resultant curves of transmissivity parameters versus fracture set scale would only previously have been obtainable from hydraulic tests conducted with increasing test interval length and with degrading equipment precision. Finally, on the basis of the properties of the proposed method, we propose guidelines for the design of fixed interval length hydraulic testing programs that require minimal prior knowledge of the rock.
Efficiency at maximum power output of quantum heat engines under finite-time operation
Wang, Jianhui; He, Jizhou; Wu, Zhaoqi
2012-03-01
We study the efficiency at maximum power, ηm, of irreversible quantum Carnot engines (QCEs) that perform finite-time cycles between a hot and a cold reservoir at temperatures Th and Tc, respectively. For QCEs in the reversible limit (long cycle period, zero dissipation), ηm becomes identical to the Carnot efficiency ηC=1-Tc/Th. For QCE cycles in which nonadiabatic dissipation and the time spent on two adiabats are included, the efficiency ηm at maximum power output is bounded from above by ηC/(2-ηC) and from below by ηC/2. In the case of symmetric dissipation, the Curzon-Ahlborn efficiency ηCA=1-Tc/Th is recovered under the condition that the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation.
Maximum efficiency of state-space models of nanoscale energy conversion devices.
Einax, Mario; Nitzan, Abraham
2016-07-07
The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage.
Maximum efficiency of state-space models of nanoscale energy conversion devices
Einax, Mario; Nitzan, Abraham
2016-07-01
The performance of nano-scale energy conversion devices is studied in the framework of state-space models where a device is described by a graph comprising states and transitions between them represented by nodes and links, respectively. Particular segments of this network represent input (driving) and output processes whose properly chosen flux ratio provides the energy conversion efficiency. Simple cyclical graphs yield Carnot efficiency for the maximum conversion yield. We give general proof that opening a link that separate between the two driving segments always leads to reduced efficiency. We illustrate these general result with simple models of a thermoelectric nanodevice and an organic photovoltaic cell. In the latter an intersecting link of the above type corresponds to non-radiative carriers recombination and the reduced maximum efficiency is manifested as a smaller open-circuit voltage.
Efficiency at maximum power output of quantum heat engines under finite-time operation.
Wang, Jianhui; He, Jizhou; Wu, Zhaoqi
2012-03-01
We study the efficiency at maximum power, η(m), of irreversible quantum Carnot engines (QCEs) that perform finite-time cycles between a hot and a cold reservoir at temperatures T(h) and T(c), respectively. For QCEs in the reversible limit (long cycle period, zero dissipation), η(m) becomes identical to the Carnot efficiency η(C)=1-T(c)/T(h). For QCE cycles in which nonadiabatic dissipation and the time spent on two adiabats are included, the efficiency η(m) at maximum power output is bounded from above by η(C)/(2-η(C)) and from below by η(C)/2. In the case of symmetric dissipation, the Curzon-Ahlborn efficiency η(CA)=1-√(T(c)/T(h)) is recovered under the condition that the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation.
Osterloh, Frank E
2014-10-02
The Shockley-Queisser analysis provides a theoretical limit for the maximum energy conversion efficiency of single junction photovoltaic cells. But besides the semiconductor bandgap no other semiconductor properties are considered in the analysis. Here, we show that the maximum conversion efficiency is limited further by the excited state entropy of the semiconductors. The entropy loss can be estimated with the modified Sackur-Tetrode equation as a function of the curvature of the bands, the degeneracy of states near the band edges, the illumination intensity, the temperature, and the band gap. The application of the second law of thermodynamics to semiconductors provides a simple explanation for the observed high performance of group IV, III-V, and II-VI materials with strong covalent bonding and for the lower efficiency of transition metal oxides containing weakly interacting metal d orbitals. The model also predicts efficient energy conversion with quantum confined and molecular structures in the presence of a light harvesting mechanism.
Latella Ivan
2014-01-01
Full Text Available We analyse the process of conversion of near-field thermal radiation into usable work by considering the radiation emitted between two planar sources supporting surface phonon-polaritons. The maximum work flux that can be extracted from the radiation is obtained taking into account that the spectral flux of modes is mainly dominated by these surface modes. The thermodynamic efficiencies are discussed and an upper bound for the first law efficiency is obtained for this process.
Ouerdane, Henni; Goupil, Christophe; Lecoeur, Philippe
2014-01-01
[...] By the beginning of the 20th century, the principles of thermodynamics were summarized into the so-called four laws, which were, as it turns out, definitive negative answers to the doomed quests for perpetual motion machines. As a matter of fact, one result of Sadi Carnot's work was precisely that the heat-to-work conversion process is fundamentally limited; as such, it is considered as a first version of the second law of thermodynamics. Although it was derived from Carnot's unrealistic model, the upper bound on the thermodynamic conversion efficiency, known as the Carnot efficiency, became a paradigm as the next target after the failure of the perpetual motion ideal. In the 1950's, Jacques Yvon published a conference paper containing the necessary ingredients for a new class of models, and even a formula, not so different from that of Carnot's efficiency, which later would become the new efficiency reference. Yvon's first analysis [...] went fairly unnoticed for twenty years, until Frank Curzon and Bo...
Lund-Hansen, Lars Chresten; Nielsen, Morten Holtegaard; Bruhn, Annette
2008-01-01
LB where Secchi depth reaches a minimum. Stratification showed a clear minimum in central LB where extended mixing prevails whereas strong stratification occurred in northern and southern LB. It is shown that mixed conditions in central LB were related to hydraulic control and super-critical flow...... conditions, as current derived energy for the mixing by comparison was too low. Nutrient (NO2 + NO3) concentrations remained high (~ 5 μM) in the bottom layer following the spring bloom. It is shown that there is a more or less continuous inflow of nutrient rich bottom water into central LB, which through...
Design of Asymmetrical Relay Resonators for Maximum Efficiency of Wireless Power Transfer
Bo-Hee Choi
2016-01-01
Full Text Available This paper presents a new design method of asymmetrical relay resonators for maximum wireless power transfer. A new design method for relay resonators is demanded because maximum power transfer efficiency (PTE is not obtained at the resonant frequency of unit resonator. The maximum PTE for relay resonators is obtained at the different resonances of unit resonator. The optimum design of asymmetrical relay is conducted by both the optimum placement and the optimum capacitance of resonators. The optimum placement is found by scanning the positions of the relays and optimum capacitance can be found by using genetic algorithm (GA. The PTEs are enhanced when capacitance is optimally designed by GA according to the position of relays, respectively, and then maximum efficiency is obtained at the optimum placement of relays. The capacitance of the second resonator to nth resonator and the load resistance should be determined for maximum efficiency while the capacitance of the first resonator and the source resistance are obtained for the impedance matching. The simulated and measured results are in good agreement.
David S. Schechter
2003-10-01
This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling the fluid flow in fracture surface, examining the fluid transfer mechanisms and describing the fracture aperture distribution under different overburden pressure using X-ray CT scanner.
David S. Schechter
2004-04-26
This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on investigating the effect of CO{sub 2} injection rates in homogeneous and fractured cores on oil recovery and a strategy to mitigate CO{sub 2} bypassing in a fractured core.
3D Navier-Stokes Simulations of a rotor designed for Maximum Aerodynamic Efficiency
Johansen, Jeppe; Madsen, Helge. Aa.; Gaunaa, Mac
2007-01-01
The present paper describes the design of a three-bladed wind turbine rotor taking into account maximum aerodynamic efficiency only and not considering structural as well as offdesign issues. The rotor was designed assuming constant induction for most of the blade span, but near the tip region a ...
Wu, Feilong; He, Jizhou; Ma, Yongli; Wang, Jianhui
2014-12-01
We consider the efficiency at maximum power of a quantum Otto engine, which uses a spin or a harmonic system as its working substance and works between two heat reservoirs at constant temperatures Th and Tc (Otto engine working in the linear-response regime.
Wang, Jianhui; He, Jizhou
2012-11-01
We investigate the efficiency at the maximum power output (EMP) of an irreversible Carnot engine performing finite-time cycles between two reservoirs at constant temperatures T(h) and T(c) (Carnot efficiency, whether the internally dissipative friction is considered or not. When dissipations of two "isothermal" and two "adiabatic" processes are symmetric, respectively, and the time allocation between the adiabats and the contact time with the reservoir satisfy a certain relation, the Curzon-Ahlborn (CA) efficiency η(CA) = 1-sqrt[T(c)/T(h)] is derived.
Efficiency at and near maximum power of low-dissipation heat engines.
Holubec, Viktor; Ryabov, Artem
2015-11-01
A universality in optimization of trade-off between power and efficiency for low-dissipation Carnot cycles is presented. It is shown that any trade-off measure expressible in terms of efficiency and the ratio of power to its maximum value can be optimized independently of most details of the dynamics and of the coupling to thermal reservoirs. The result is demonstrated on two specific trade-off measures. The first one is designed for finding optimal efficiency for a given output power and clearly reveals diseconomy of engines working at maximum power. As the second example we derive universal lower and upper bounds on the efficiency at maximum trade-off given by the product of power and efficiency. The results are illustrated on a model of a diffusion-based heat engine. Such engines operate in the low-dissipation regime given that the used driving minimizes the work dissipated during the isothermal branches. The peculiarities of the corresponding optimization procedure are reviewed and thoroughly discussed.
Efficiency at and near maximum power of low-dissipation heat engines
Holubec, Viktor; Ryabov, Artem
2015-11-01
A universality in optimization of trade-off between power and efficiency for low-dissipation Carnot cycles is presented. It is shown that any trade-off measure expressible in terms of efficiency and the ratio of power to its maximum value can be optimized independently of most details of the dynamics and of the coupling to thermal reservoirs. The result is demonstrated on two specific trade-off measures. The first one is designed for finding optimal efficiency for a given output power and clearly reveals diseconomy of engines working at maximum power. As the second example we derive universal lower and upper bounds on the efficiency at maximum trade-off given by the product of power and efficiency. The results are illustrated on a model of a diffusion-based heat engine. Such engines operate in the low-dissipation regime given that the used driving minimizes the work dissipated during the isothermal branches. The peculiarities of the corresponding optimization procedure are reviewed and thoroughly discussed.
Optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits.
Ozkan, Fahri; Tuna, M Cihat; Baylar, Ahmet; Ozturk, Mualla
2014-01-01
Oxygen is an important component of water quality and its ability to sustain life. Water aeration is the process of introducing air into a body of water to increase its oxygen saturation. Water aeration can be accomplished in a variety of ways, for instance, closed-conduit aeration. High-speed flow in a closed conduit involves air-water mixture flow. The air flow results from the subatmospheric pressure downstream of the gate. The air entrained by the high-speed flow is supplied by the air vent. The air entrained into the flow in the form of a large number of bubbles accelerates oxygen transfer and hence also increases aeration efficiency. In the present work, the optimum air-demand ratio for maximum aeration efficiency in high-head gated circular conduits was studied experimentally. Results showed that aeration efficiency increased with the air-demand ratio to a certain point and then aeration efficiency did not change with a further increase of the air-demand ratio. Thus, there was an optimum value for the air-demand ratio, depending on the Froude number, which provides maximum aeration efficiency. Furthermore, a design formula for aeration efficiency was presented relating aeration efficiency to the air-demand ratio and Froude number.
A teaspoon pump for pumping blood with high hydraulic efficiency and low hemolysis potential.
Dame, D
1996-06-01
Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.
Kajino, Tsutomu; Namazue, Eitaro; Ueno, Yutaka
1995-12-31
The front suspension unit for motorcycles is one of the functional parts for which continuous engineering improvement is required for advanced driveability. Especially, the ones for off-road motocross racing are frequently required to have their energy absorbing properties, ability to maintain tire-to-ground contact, driving comfort, etc. to be improved to meet the challenges of the racing courses which include many jumps, to exceed the performance of competitors, and to match the ever-improving performance of the engines and frames. To cope with the situation, the operability, rigidity and hydraulic pressure producing mechanism needs to be upgraded. As part of an improvement program, the authors have developed a air-oil separated front suspension which the authors have called the ``twin chamber`` suspension. In this study, the authors compared the hydraulic pressure producing efficiency of the air-oil separated suspension with that of the conventional single chamber construction. The results of the comparison showed that the twin chamber suspension is less affected by the pressure hysteresis by 8% or more at the piston area and 50% or more at the partition area than the conventional suspension. In addition, for the twin chamber suspension, the rise of pressure becomes smoother to give a quicker response as the velocity increases.
Efficiency at maximum power of thermochemical engines with near-independent particles.
Luo, Xiaoguang; Liu, Nian; Qiu, Teng
2016-03-01
Two-reservoir thermochemical engines are established by using near-independent particles (including Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein particles) as the working substance. Particle and heat fluxes can be formed based on the temperature and chemical potential gradients between two different reservoirs. A rectangular-type energy filter with width Γ is introduced for each engine to weaken the coupling between the particle and heat fluxes. The efficiency at maximum power of each particle system decreases monotonously from an upper bound η(+) to a lower bound η(-) when Γ increases from 0 to ∞. It is found that the η(+) values for all three systems are bounded by η(C)/2 ≤ η(+) ≤ η(C)/(2-η(C)) due to strong coupling, where η(C) is the Carnot efficiency. For the Bose-Einstein system, it is found that the upper bound is approximated by the Curzon-Ahlborn efficiency: η(CA)=1-sqrt[1-η(C)]. When Γ → ∞, the intrinsic maximum powers are proportional to the square of the temperature difference of the two reservoirs for all three systems, and the corresponding lower bounds of efficiency at maximum power can be simplified in the same form of η(-)=η(C)/[1+a(0)(2-η(C))].
Efficiency at maximum power of thermochemical engines with near-independent particles
Luo, Xiaoguang; Liu, Nian; Qiu, Teng
2016-03-01
Two-reservoir thermochemical engines are established by using near-independent particles (including Maxwell-Boltzmann, Fermi-Dirac, and Bose-Einstein particles) as the working substance. Particle and heat fluxes can be formed based on the temperature and chemical potential gradients between two different reservoirs. A rectangular-type energy filter with width Γ is introduced for each engine to weaken the coupling between the particle and heat fluxes. The efficiency at maximum power of each particle system decreases monotonously from an upper bound η+ to a lower bound η- when Γ increases from 0 to ∞ . It is found that the η+ values for all three systems are bounded by ηC/2 ≤η+≤ηC/(2 -ηC ) due to strong coupling, where ηC is the Carnot efficiency. For the Bose-Einstein system, it is found that the upper bound is approximated by the Curzon-Ahlborn efficiency: ηCA=1 -√{1 -ηC } . When Γ →∞ , the intrinsic maximum powers are proportional to the square of the temperature difference of the two reservoirs for all three systems, and the corresponding lower bounds of efficiency at maximum power can be simplified in the same form of η-=ηC/[1 +a0(2 -ηC ) ] .
Laura Castro
2011-01-01
Full Text Available On-site power and mass flow rate measurements were conducted in a hydroelectric power plant (Mexico. Mass flow rate was obtained using Gibson's water hammer-based method. A numerical counterpart was carried out by using the commercial CFD software, and flow simulations were performed to principal components of a hydraulic turbine: runner and draft tube. Inlet boundary conditions for the runner were obtained from a previous simulation conducted in the spiral case. The computed results at the runner's outlet were used to conduct the subsequent draft tube simulation. The numerical results from the runner's flow simulation provided data to compute the torque and the turbine's power. Power-versus-efficiency curves were built, and very good agreement was found between experimental and numerical data.
The ACT{sup 2} project: Demonstration of maximum energy efficiency in real buildings
Crawley, D.B. [Pacific Northwest Lab., Richland, WA (United States); Krieg, B.L. [Pacific Gas and Electric Co., San Ramon, CA (United States)
1991-11-01
A large US utility recently began a project to determine whether the use of new energy-efficient end-use technologies and systems would economically achieve substantial energy savings (perhaps as high as 75% over current practice). Using a field-based demonstration approach, the Advanced Customer Technology Test (ACT{sup 2}) for Maximum Energy Efficiency is providing information on the maximum energy savings possible when integrated packages of new high-efficiency end-use technologies are incorporated into commercial and residential buildings and industrial and agricultural processes. This paper details the underlying rationale, approach, results to date, and future plans for ACT{sup 2}. The ultimate goal is energy efficiency (doing more with less energy) rather than energy conservation (freezing in the dark). In this paper, we first explain why a major United States utility is committed to pursuing demand-side management so aggressively. Next, we discuss the approach the utility chose for conducting the ACT{sup 2} project. We then review results obtained to date from the project`s pilot demonstration site. Last, we describe other related demonstration projects being proposed by the utility.
The ACT sup 2 project: Demonstration of maximum energy efficiency in real buildings
Crawley, D.B. (Pacific Northwest Lab., Richland, WA (United States)); Krieg, B.L. (Pacific Gas and Electric Co., San Ramon, CA (United States))
1991-11-01
A large US utility recently began a project to determine whether the use of new energy-efficient end-use technologies and systems would economically achieve substantial energy savings (perhaps as high as 75% over current practice). Using a field-based demonstration approach, the Advanced Customer Technology Test (ACT{sup 2}) for Maximum Energy Efficiency is providing information on the maximum energy savings possible when integrated packages of new high-efficiency end-use technologies are incorporated into commercial and residential buildings and industrial and agricultural processes. This paper details the underlying rationale, approach, results to date, and future plans for ACT{sup 2}. The ultimate goal is energy efficiency (doing more with less energy) rather than energy conservation (freezing in the dark). In this paper, we first explain why a major United States utility is committed to pursuing demand-side management so aggressively. Next, we discuss the approach the utility chose for conducting the ACT{sup 2} project. We then review results obtained to date from the project's pilot demonstration site. Last, we describe other related demonstration projects being proposed by the utility.
Efficiency at maximum power output of linear irreversible Carnot-like heat engines.
Wang, Yang; Tu, Z C
2012-01-01
The efficiency at maximum power output of linear irreversible Carnot-like heat engines is investigated based on the assumption that the rate of irreversible entropy production of the working substance in each "isothermal" process is a quadratic form of the heat exchange rate between the working substance and the reservoir. It is found that the maximum power output corresponds to minimizing the irreversible entropy production in two isothermal processes of the Carnot-like cycle, and that the efficiency at maximum power output has the form η(mP)=η(C)/(2-γη(C)), where η(C) is the Carnot efficiency, while γ depends on the heat transfer coefficients between the working substance and two reservoirs. The value of η(mP) is bounded between η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)). These results are consistent with those obtained by Chen and Yan [J. Chem. Phys. 90, 3740 (1989)] based on the endoreversible assumption, those obtained by Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] based on the low-dissipation assumption, and those obtained by Schmiedl and Seifert [Europhys. Lett. 81, 20003 (2008)] for stochastic heat engines which in fact also satisfy the low-dissipation assumption. Additionally, we find that the endoreversible assumption happens to hold for Carnot-like heat engines operating at the maximum power output based on our fundamental assumption, and that the Carnot-like heat engines that we focused on do not strictly satisfy the low-dissipation assumption, which implies that the low-dissipation assumption or our fundamental assumption is a sufficient but non-necessary condition for the validity of η(mP)=η(C)/(2-γη(C)) as well as the existence of two bounds, η(-)≡η(C)/2 and η(+)≡η(C)/(2-η(C)).
The maximum power efficiency 1-√τ: Research, education, and bibliometric relevance
Calvo Hernández, A.; Roco, J. M. M.; Medina, A.; Velasco, S.; Guzmán-Vargas, L.
2015-07-01
The well-known efficiency at maximum power for a cyclic system working between hot T h and low T c temperatures given by the equation 1-√ τ( τ= T c /T h), has become a landmark result with regards to the thermodynamic optimization of a great variety of energy converters. Its wide applicability and sole dependence on the external heat bath temperatures (as the Carnot efficiency does) allows for an easy comparison with experimental efficiencies leading to a striking fair agreement. Reversible, finite-time, and linear-irreversible derivations are analyzed in order to show a broader perspective about its meaning from both researching and pedagogical point of views. Its scientific relevance and historical development are also analyzed in this work by means of some bibliometric data. This article is supplemented with comments by Hong Qian and a final reply by the authors.
Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling.
Yan, H; Guo, Hao
2012-01-01
We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson engines. While in the short contact time limit, which corresponds to the Carnot cycle, the same efficiency bounds as that from Esposito et al. [Phys. Rev. Lett. 105, 150603 (2010)] are derived. In both cases, the thermal efficiency decreases as the ratio between the heat capacities of the working medium during heating and cooling stages increases. This might provide instructions for designing real engines.
Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling
Yan, H.; Guo, Hao
2012-01-01
We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson engines. While in the short contact time limit, which corresponds to the Carnot cycle, the same efficiency bounds as that from Esposito [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.105.150603 105, 150603 (2010)] are derived. In both cases, the thermal efficiency decreases as the ratio between the heat capacities of the working medium during heating and cooling stages increases. This might provide instructions for designing real engines.
Wu, Feilong; He, Jizhou; Ma, Yongli; Wang, Jianhui
2014-12-01
We consider the efficiency at maximum power of a quantum Otto engine, which uses a spin or a harmonic system as its working substance and works between two heat reservoirs at constant temperatures T(h) and T(c) (power based on these two different kinds of quantum systems are bounded from the upper side by the same expression η(mp)≤η(+)≡η(C)(2)/[η(C)-(1-η(C))ln(1-η(C))] with η(C)=1-T(c)/T(h) as the Carnot efficiency. This expression η(mp) possesses the same universality of the CA efficiency η(CA)=1-√(1-η(C)) at small relative temperature difference. Within the context of irreversible thermodynamics, we calculate the Onsager coefficients and show that the value of η(CA) is indeed the upper bound of EMP for an Otto engine working in the linear-response regime.
Efficiency at maximum power output for an engine with a passive piston
Sano, Tomohiko G.; Hayakawa, Hisao
2016-08-01
Efficiency at maximum power (MP) output for an engine with a passive piston without mechanical controls between two reservoirs is studied theoretically. We enclose a hard core gas partitioned by a massive piston in a temperature-controlled container and analyze the efficiency at MP under a heating and cooling protocol without controlling the pressure acting on the piston from outside. We find the following three results: (i) The efficiency at MP for a dilute gas is close to the Chambadal-Novikov-Curzon-Ahlborn (CNCA) efficiency if we can ignore the sidewall friction and the loss of energy between a gas particle and the piston, while (ii) the efficiency for a moderately dense gas becomes smaller than the CNCA efficiency even when the temperature difference of the reservoirs is small. (iii) Introducing the Onsager matrix for an engine with a passive piston, we verify that the tight coupling condition for the matrix of the dilute gas is satisfied, while that of the moderately dense gas is not satisfied because of the inevitable heat leak. We confirm the validity of these results using the molecular dynamics simulation and introducing an effective mean-field-like model which we call the stochastic mean field model.
Selva, J
2011-01-01
This paper presents an efficient method to compute the maximum likelihood (ML) estimation of the parameters of a complex 2-D sinusoidal, with the complexity order of the FFT. The method is based on an accurate barycentric formula for interpolating band-limited signals, and on the fact that the ML cost function can be viewed as a signal of this type, if the time and frequency variables are switched. The method consists in first computing the DFT of the data samples, and then locating the maximum of the cost function by means of Newton's algorithm. The fact is that the complexity of the latter step is small and independent of the data size, since it makes use of the barycentric formula for obtaining the values of the cost function and its derivatives. Thus, the total complexity order is that of the FFT. The method is validated in a numerical example.
Apertet, Y; Ouerdane, H; Goupil, C; Lecoeur, Ph
2012-03-01
Energy conversion efficiency at maximum output power, which embodies the essential characteristics of heat engines, is the main focus of the present work. The so-called Curzon and Ahlborn efficiency η(CA) is commonly believed to be an absolute reference for real heat engines; however, a different but general expression for the case of stochastic heat engines, η(SS), was recently found and then extended to low-dissipation engines. The discrepancy between η(CA) and η(SS) is here analyzed considering different irreversibility sources of heat engines, of both internal and external types. To this end, we choose a thermoelectric generator operating in the strong-coupling regime as a physical system to qualitatively and quantitatively study the impact of the nature of irreversibility on the efficiency at maximum output power. In the limit of pure external dissipation, we obtain η(CA), while η(SS) corresponds to the case of pure internal dissipation. A continuous transition between from one extreme to the other, which may be operated by tuning the different sources of irreversibility, also is evidenced.
Stysley, Paul; Coyle, Barry; Clarke, Greg; Poulios, Demetrios; Kay, Richard
2015-01-01
The Global Ecosystems Dynamics Investigation (GEDI) is a planned mission sending a LIDAR instrument to the International Space Station that will employ three NASA laser transmitters. This instrument will produce parallel tracks on the Earth's surface that will provide global 3D vegetation canopy measurements. To meet the mission goals a total of 5 High Output Maximum Efficiency Resonator lasers will to be built (1 ETU + 3 Flight + 1 spare) in-house at NASA-GSFC. This presentation will summarize the HOMER design, the testing the design has completed in the past, and the plans to successfully build the units needed for the GEDI mission.
Efficiency and its bounds for thermal engines at maximum power using Newton's law of cooling
Yan, H; Guo, H.
2012-01-01
We study a thermal engine model for which Newton's cooling law is obeyed during heat transfer processes. The thermal efficiency and its bounds at maximum output power are derived and discussed. This model, though quite simple, can be applied not only to Carnot engines but also to four other types of engines. For the long thermal contact time limit, new bounds, tighter than what were known before, are obtained. In this case, this model can simulate Otto, Joule-Brayton, Diesel, and Atkinson eng...
Efficiency at maximum power of a quantum heat engine based on two coupled oscillators.
Wang, Jianhui; Ye, Zhuolin; Lai, Yiming; Li, Weisheng; He, Jizhou
2015-06-01
We propose and theoretically investigate a system of two coupled harmonic oscillators as a heat engine. We show how these two coupled oscillators within undamped regime can be controlled to realize an Otto cycle that consists of two adiabatic and two isochoric processes. During the two isochores the harmonic system is embedded in two heat reservoirs at constant temperatures T(h) and T(c)(semigroup approach to model the thermal relaxation dynamics along the two isochoric processes, and we find the upper bound of efficiency at maximum power (EMP) η* to be a function of the Carnot efficiency η(C)(=1-T(c)/T(h)): η*≤η(+)≡η(C)(2)/[η(C)-(1-η(C))ln(1-η(C))], identical to those previously derived from ideal (noninteracting) microscopic, mesoscopic, and macroscopic systems.
Efficient Photovoltaic System Maximum Power Point Tracking Using a New Technique
Mehdi Seyedmahmoudian
2016-03-01
Full Text Available Partial shading is an unavoidable condition which significantly reduces the efficiency and stability of a photovoltaic (PV system. When partial shading occurs the system has multiple-peak output power characteristics. In order to track the global maximum power point (GMPP within an appropriate period a reliable technique is required. Conventional techniques such as hill climbing and perturbation and observation (P&O are inadequate in tracking the GMPP subject to this condition resulting in a dramatic reduction in the efficiency of the PV system. Recent artificial intelligence methods have been proposed, however they have a higher computational cost, slower processing time and increased oscillations which results in further instability at the output of the PV system. This paper proposes a fast and efficient technique based on Radial Movement Optimization (RMO for detecting the GMPP under partial shading conditions. The paper begins with a brief description of the behavior of PV systems under partial shading conditions followed by the introduction of the new RMO-based technique for GMPP tracking. Finally, results are presented to demonstration the performance of the proposed technique under different partial shading conditions. The results are compared with those of the PSO method, one of the most widely used methods in the literature. Four factors, namely convergence speed, efficiency (power loss reduction, stability (oscillation reduction and computational cost, are considered in the comparison with the PSO technique.
Bounds and phase diagram of efficiency at maximum power for tight-coupling molecular motors.
Tu, Z C
2013-02-01
The efficiency at maximum power (EMP) for tight-coupling molecular motors is investigated within the framework of irreversible thermodynamics. It is found that the EMP depends merely on the constitutive relation between the thermodynamic current and force. The motors are classified into four generic types (linear, superlinear, sublinear, and mixed types) according to the characteristics of the constitutive relation, and then the corresponding ranges of the EMP for these four types of molecular motors are obtained. The exact bounds of the EMP are derived and expressed as the explicit functions of the free energy released by the fuel in each motor step. A phase diagram is constructed which clearly shows how the region where the parameters (the load distribution factor and the free energy released by the fuel in each motor step) are located can determine whether the value of the EMP is larger or smaller than 1/2. This phase diagram reveals that motors using ATP as fuel under physiological conditions can work at maximum power with higher efficiency (> 1/2) for a small load distribution factor (< 0.1).
Abdellah Ait moussa
2014-08-01
Full Text Available The design and optimization of turbo machine impellers such as those in pumps and turbines is a highly complicated task due to the complex three-dimensional shape of the impeller blades and surrounding devices. Small differences in geometry can lead to significant changes in the performance of these machines. We report here an efficient numerical technique that automatically optimizes the geometry of these blades for maximum performance. The technique combines, mathematical modeling of the impeller blades using non-uniform rational B-spline (NURBS, Computational fluid dynamics (CFD with Geometry Parameterizations in turbulent flow simulation and the Globalized and bounded Nelder-Mead (GBNM algorithm in geometry optimization.
John Leju Celestino Ladu
2014-02-01
Full Text Available The study examined the removal efficiency of upflow anaerobic filter reactor fed continuously with campus domestic wastewater at different hydraulic retention time and wastewater temperature. The reactor was filled with non woven filter materials and operated at hydraulic retention time ranging from 1 to 6 days and wastewater temperature ranging from 20 to 30C. At that operating condition, the result revealed no significant difference for Carbonaceous (COD and nutrients materials except there was significant production of gas. The result revealed that increase in HRT and wastewater temperature improves removal performance of the reactor. The overall reactor removal efficiency for COD, TN, NH4+-N, NO3-N and TP concentration were 51, 22, 21, 28 and 10% and 61 35, 37, 49 and 27% in the anaerobic and anoxic columns, respectively. The experimental system was capable of instantaneous removal of the carbonaceous, nitrogenous and phosphorous compounds.
Simulation of maximum light use efficiency for some typical vegetation types in China
无
2006-01-01
Maximum light use efficiency (εmax) is a key parameter for the estimation of net primary productivity (NPP) derived from remote sensing data. There are still many divergences about its value for each vegetation type. The εmax for some typical vegetation types in China is simulated using a modified least squares function based on NOAA/AVHRR remote sensing data and field-observed NPP data. The vegetation classification accuracy is introduced to the process. The sensitivity analysis of εmax to vegetation classification accuracy is also conducted. The results show that the simulated values of εmax are greater than the value used in CASA model, and less than the values simulated with BIOME-BGC model. This is consistent with some other studies. The relative error of εmax resulting from classification accuracy is -5.5%―8.0%. This indicates that the simulated values of εmax are reliable and stable.
Smolin, John A; Gambetta, Jay M; Smith, Graeme
2012-02-17
We provide an efficient method for computing the maximum-likelihood mixed quantum state (with density matrix ρ) given a set of measurement outcomes in a complete orthonormal operator basis subject to Gaussian noise. Our method works by first changing basis yielding a candidate density matrix μ which may have nonphysical (negative) eigenvalues, and then finding the nearest physical state under the 2-norm. Our algorithm takes at worst O(d(4)) for the basis change plus O(d(3)) for finding ρ where d is the dimension of the quantum state. In the special case where the measurement basis is strings of Pauli operators, the basis change takes only O(d(3)) as well. The workhorse of the algorithm is a new linear-time method for finding the closest probability distribution (in Euclidean distance) to a set of real numbers summing to one.
Cushing, Scott K; Bristow, Alan D; Wu, Nianqiang
2015-11-28
Plasmonics can enhance solar energy conversion in semiconductors by light trapping, hot electron transfer, and plasmon-induced resonance energy transfer (PIRET). The multifaceted response of the plasmon and multiple interaction pathways with the semiconductor makes optimization challenging, hindering design of efficient plasmonic architectures. Therefore, in this paper we use a density matrix model to capture the interplay between scattering, hot electrons, and dipole-dipole coupling through the plasmon's dephasing, including both the coherent and incoherent dynamics necessary for interactions on the plasmon's timescale. The model is extended to Shockley-Queisser limit calculations for both photovoltaics and solar-to-chemical conversion, revealing the optimal application of each enhancement mechanism based on plasmon energy, semiconductor energy, and plasmon dephasing. The results guide application of plasmonic solar-energy harvesting, showing which enhancement mechanism is most appropriate for a given semiconductor's weakness, and what nanostructures can achieve the maximum enhancement.
2008-01-01
Optimal configuration of a class of endoreversible heat engines with fixed duration,input energy and radiative heat transfer law (q∝Δ(T4)) is determined. The optimal cycle that maximizes the efficiency of the heat engine is obtained by using opti-mal-control theory,and the differential equations are solved by the Taylor series expansion. It is shown that the optimal cycle has eight branches including two isothermal branches,four maximum-efficiency branches,and two adiabatic branches. The interval of each branch is obtained,as well as the solutions of the temperatures of the heat reservoirs and the working fluid. A numerical example is given. The obtained results are compared with those obtained with the Newton’s heat transfer law for the maximum efficiency objective,those with linear phe-nomenological heat transfer law for the maximum efficiency objective,and those with radiative heat transfer law for the maximum power output objective.
SONG HanJiang; CHEN LinGen; SUN FengRui
2008-01-01
Optimal configuration of a class of endoreversible heat engines with fixed duration, input energy and radiative heat transfer law (q∝△(T4)) is determined. The optimal cycle that maximizes the efficiency of the heat engine is obtained by using opti-mal-control theory, and the differential equations are solved by the Taylor series expansion. It is shown that the optimal cycle has eight branches including two isothermal branches, four maximum-efficiency branches, and two adiabatic branches. The interval of each branch is obtained, as well as the solutions of the temperatures of the heat reservoirs and the working fluid. A numerical example is given. The obtained results are compared with those obtained with the Newton's heat transfer law for the maximum efficiency objective, those with linear phe-nomenological heat transfer law for the maximum efficiency objective, and those with radiative heat transfer law for the maximum power output objective.
JUN YEOB LEE
2014-10-01
Full Text Available During the development process of a thermal-hydraulic system code, a non-regression test (NRT must be performed repeatedly in order to prevent software regression. The NRT process, however, is time-consuming and labor-intensive. Thus, automation of this process is an ideal solution. In this study, we have developed a program to support an efficient NRT for the SPACE code and demonstrated its usability. This results in a high degree of efficiency for code development. The program was developed using the Visual Basic for Applications and designed so that it can be easily customized for the NRT of other computer codes.
Meller, Michael; Chipka, Jordan; Volkov, Alexander; Bryant, Matthew; Garcia, Ephrahim
2016-11-03
Hydraulic control systems have become increasingly popular as the means of actuation for human-scale legged robots and assistive devices. One of the biggest limitations to these systems is their run time untethered from a power source. One way to increase endurance is by improving actuation efficiency. We investigate reducing servovalve throttling losses by using a selective recruitment artificial muscle bundle comprised of three motor units. Each motor unit is made up of a pair of hydraulic McKibben muscles connected to one servovalve. The pressure and recruitment state of the artificial muscle bundle can be adjusted to match the load in an efficient manner, much like the firing rate and total number of recruited motor units is adjusted in skeletal muscle. A volume-based effective initial braid angle is used in the model of each recruitment level. This semi-empirical model is utilized to predict the efficiency gains of the proposed variable recruitment actuation scheme versus a throttling-only approach. A real-time orderly recruitment controller with pressure-based thresholds is developed. This controller is used to experimentally validate the model-predicted efficiency gains of recruitment on a robot arm. The results show that utilizing variable recruitment allows for much higher efficiencies over a broader operating envelope.
Improved efficiency of maximum likelihood analysis of time series with temporally correlated errors
Langbein, John O.
2017-01-01
Most time series of geophysical phenomena have temporally correlated errors. From these measurements, various parameters are estimated. For instance, from geodetic measurements of positions, the rates and changes in rates are often estimated and are used to model tectonic processes. Along with the estimates of the size of the parameters, the error in these parameters needs to be assessed. If temporal correlations are not taken into account, or each observation is assumed to be independent, it is likely that any estimate of the error of these parameters will be too low and the estimated value of the parameter will be biased. Inclusion of better estimates of uncertainties is limited by several factors, including selection of the correct model for the background noise and the computational requirements to estimate the parameters of the selected noise model for cases where there are numerous observations. Here, I address the second problem of computational efficiency using maximum likelihood estimates (MLE). Most geophysical time series have background noise processes that can be represented as a combination of white and power-law noise, 1/fα">1/fα1/fα with frequency, f. With missing data, standard spectral techniques involving FFTs are not appropriate. Instead, time domain techniques involving construction and inversion of large data covariance matrices are employed. Bos et al. (J Geod, 2013. doi:10.1007/s00190-012-0605-0) demonstrate one technique that substantially increases the efficiency of the MLE methods, yet is only an approximate solution for power-law indices >1.0 since they require the data covariance matrix to be Toeplitz. That restriction can be removed by simply forming a data filter that adds noise processes rather than combining them in quadrature. Consequently, the inversion of the data covariance matrix is simplified yet provides robust results for a wider range of power-law indices.
Improved efficiency of maximum likelihood analysis of time series with temporally correlated errors
Langbein, John
2017-02-01
Most time series of geophysical phenomena have temporally correlated errors. From these measurements, various parameters are estimated. For instance, from geodetic measurements of positions, the rates and changes in rates are often estimated and are used to model tectonic processes. Along with the estimates of the size of the parameters, the error in these parameters needs to be assessed. If temporal correlations are not taken into account, or each observation is assumed to be independent, it is likely that any estimate of the error of these parameters will be too low and the estimated value of the parameter will be biased. Inclusion of better estimates of uncertainties is limited by several factors, including selection of the correct model for the background noise and the computational requirements to estimate the parameters of the selected noise model for cases where there are numerous observations. Here, I address the second problem of computational efficiency using maximum likelihood estimates (MLE). Most geophysical time series have background noise processes that can be represented as a combination of white and power-law noise, 1/f^{α } with frequency, f. With missing data, standard spectral techniques involving FFTs are not appropriate. Instead, time domain techniques involving construction and inversion of large data covariance matrices are employed. Bos et al. (J Geod, 2013. doi: 10.1007/s00190-012-0605-0) demonstrate one technique that substantially increases the efficiency of the MLE methods, yet is only an approximate solution for power-law indices >1.0 since they require the data covariance matrix to be Toeplitz. That restriction can be removed by simply forming a data filter that adds noise processes rather than combining them in quadrature. Consequently, the inversion of the data covariance matrix is simplified yet provides robust results for a wider range of power-law indices.
Improved efficiency of maximum likelihood analysis of time series with temporally correlated errors
Langbein, John
2017-08-01
Most time series of geophysical phenomena have temporally correlated errors. From these measurements, various parameters are estimated. For instance, from geodetic measurements of positions, the rates and changes in rates are often estimated and are used to model tectonic processes. Along with the estimates of the size of the parameters, the error in these parameters needs to be assessed. If temporal correlations are not taken into account, or each observation is assumed to be independent, it is likely that any estimate of the error of these parameters will be too low and the estimated value of the parameter will be biased. Inclusion of better estimates of uncertainties is limited by several factors, including selection of the correct model for the background noise and the computational requirements to estimate the parameters of the selected noise model for cases where there are numerous observations. Here, I address the second problem of computational efficiency using maximum likelihood estimates (MLE). Most geophysical time series have background noise processes that can be represented as a combination of white and power-law noise, 1/f^{α } with frequency, f. With missing data, standard spectral techniques involving FFTs are not appropriate. Instead, time domain techniques involving construction and inversion of large data covariance matrices are employed. Bos et al. (J Geod, 2013. doi: 10.1007/s00190-012-0605-0) demonstrate one technique that substantially increases the efficiency of the MLE methods, yet is only an approximate solution for power-law indices >1.0 since they require the data covariance matrix to be Toeplitz. That restriction can be removed by simply forming a data filter that adds noise processes rather than combining them in quadrature. Consequently, the inversion of the data covariance matrix is simplified yet provides robust results for a wider range of power-law indices.
Vasquez, Yaneth; Escobar, Maria C; Neculita, Carmen M; Arbeli, Ziv; Roldan, Fabio
2016-06-01
Biochemical passive treatment represents a promising option for the remediation of acid mine drainage. This study determined the effect of three hydraulic retention times (1, 2, and 4 days) on changes in system efficiency, reactive mixture, and microbial activity in bioreactors under upward flow conditions. Bioreactors were sacrificed in the weeks 8, 17 and 36, and the reactive mixture was sampled at the bottom, middle, and top layers. Physicochemical analyses were performed on reactive mixture post-treatment and correlated with sulfate-reducing bacteria and cellulolytic and dehydrogenase activity. All hydraulic retention times were efficient at increasing pH and alkalinity and removing sulfate (>60%) and metals (85-99% for Fe(2+) and 70-100% for Zn(2+)), except for Mn(2+). The longest hydraulic retention time (4 days) increased residual sulfides, deteriorated the quality of treated effluent and negatively impacted sulfate-reducing bacteria. Shortest hydraulic retention time (1 day) washed out biomass and increased input of dissolved oxygen in the reactors, leading to higher redox potential and decreasing metal removal efficiency. Concentrations of iron, zinc and metal sulfides were high in the bottom layer, especially with 2 day of hydraulic retention time. Sulfate-reducing bacteria, cellulolytic and dehydrogenase activity were higher in the middle layer at 4 days of hydraulic retention time. Hydraulic retention time had a strong influence on overall performance of passive reactors.
Murphy, Patrick Charles
1985-01-01
An algorithm for maximum likelihood (ML) estimation is developed with an efficient method for approximating the sensitivities. The algorithm was developed for airplane parameter estimation problems but is well suited for most nonlinear, multivariable, dynamic systems. The ML algorithm relies on a new optimization method referred to as a modified Newton-Raphson with estimated sensitivities (MNRES). MNRES determines sensitivities by using slope information from local surface approximations of each output variable in parameter space. The fitted surface allows sensitivity information to be updated at each iteration with a significant reduction in computational effort. MNRES determines the sensitivities with less computational effort than using either a finite-difference method or integrating the analytically determined sensitivity equations. MNRES eliminates the need to derive sensitivity equations for each new model, thus eliminating algorithm reformulation with each new model and providing flexibility to use model equations in any format that is convenient. A random search technique for determining the confidence limits of ML parameter estimates is applied to nonlinear estimation problems for airplanes. The confidence intervals obtained by the search are compared with Cramer-Rao (CR) bounds at the same confidence level. It is observed that the degree of nonlinearity in the estimation problem is an important factor in the relationship between CR bounds and the error bounds determined by the search technique. The CR bounds were found to be close to the bounds determined by the search when the degree of nonlinearity was small. Beale's measure of nonlinearity is developed in this study for airplane identification problems; it is used to empirically correct confidence levels for the parameter confidence limits. The primary utility of the measure, however, was found to be in predicting the degree of agreement between Cramer-Rao bounds and search estimates.
Moffitt, Christine M.
2016-01-01
We compared the hydrodynamics of replicate experimental mixed cell and replicate standard Burrows pond rearing systems at the Dworshak National Fish Hatchery, ID, in an effort to identify methods for improved solids removal. We measured and compared the hydraulic residence time, particle removal efficiency, and measures of velocity using several tools. Computational fluid dynamics was used first to characterize hydraulics in the proposed retrofit that included removal of the traditional Burrows pond dividing wall and establishment of four counter rotating cells with appropriate drains and inlet water jets. Hydraulic residence time was subsequently established in the four full scale test tanks using measures of conductivity of a salt tracer introduced into the systems both with and without fish present. Vertical and horizontal velocities were also measured with acoustic Doppler velocimetry in transects across each of the rearing systems. Finally, we introduced ABS sinking beads that simulated fish solids then followed the kinetics of their removal via the drains to establish relative purge rates. The mixed cell raceway provided higher mean velocities and a more uniform velocity distribution than did the Burrows pond. Vectors revealed well-defined, counter-rotating cells in the mixed cell raceway, and were likely contributing factors in achieving a relatively high particle removal efficiency-88.6% versus 8.0% during the test period. We speculate retrofits of rearing ponds to mixed cell systems will improve both the rearing environments for the fish and solids removal, improving the efficiency and bio-security of fish culture. We recommend further testing in hatchery production trials to evaluate fish physiology and growth.
Soroosh Mahmoodi
2016-01-01
Full Text Available An interesting model which was able to recuperate and reuse braking energy was investigated. It was named series hybrid hydraulic/electric system (SHHES. The innovated model was presented for heavy hybrid vehicles to overcome the existing drawbacks of single energy storage sources. The novelty of this paper was investigation of a new series hybrid vehicle with triple sources, combustion engine, electric motor, and hydraulic sources. It was simulated with MATLAB-Simulink and different operational mode of control system was investigated. The aim was to improve the efficiency of the energy-loading components in the power train system and the transmission system independently. The ability to store and reuse the kinetic energy was added to the system to prevent energy wasting while the vehicle was braking. Control models were also investigated to realize suitable control algorithms to offer the best efficiency in system components for different vehicle conditions. The torque control strategy based on fuzzy logic controller was proposed to achieve better vehicle performance while the fuel consumption was minimized. The results implied efficient storage and usage in the transmission system. A small vehicle model experimentally verified the simulation results.
An efficient approximation algorithm for finding a maximum clique using Hopfield network learning.
Wang, Rong Long; Tang, Zheng; Cao, Qi Ping
2003-07-01
In this article, we present a solution to the maximum clique problem using a gradient-ascent learning algorithm of the Hopfield neural network. This method provides a near-optimum parallel algorithm for finding a maximum clique. To do this, we use the Hopfield neural network to generate a near-maximum clique and then modify weights in a gradient-ascent direction to allow the network to escape from the state of near-maximum clique to maximum clique or better. The proposed parallel algorithm is tested on two types of random graphs and some benchmark graphs from the Center for Discrete Mathematics and Theoretical Computer Science (DIMACS). The simulation results show that the proposed learning algorithm can find good solutions in reasonable computation time.
Efficient Levenberg-Marquardt minimization of the maximum likelihood estimator for Poisson deviates
Laurence, T; Chromy, B
2009-11-10
Histograms of counted events are Poisson distributed, but are typically fitted without justification using nonlinear least squares fitting. The more appropriate maximum likelihood estimator (MLE) for Poisson distributed data is seldom used. We extend the use of the Levenberg-Marquardt algorithm commonly used for nonlinear least squares minimization for use with the MLE for Poisson distributed data. In so doing, we remove any excuse for not using this more appropriate MLE. We demonstrate the use of the algorithm and the superior performance of the MLE using simulations and experiments in the context of fluorescence lifetime imaging. Scientists commonly form histograms of counted events from their data, and extract parameters by fitting to a specified model. Assuming that the probability of occurrence for each bin is small, event counts in the histogram bins will be distributed according to the Poisson distribution. We develop here an efficient algorithm for fitting event counting histograms using the maximum likelihood estimator (MLE) for Poisson distributed data, rather than the non-linear least squares measure. This algorithm is a simple extension of the common Levenberg-Marquardt (L-M) algorithm, is simple to implement, quick and robust. Fitting using a least squares measure is most common, but it is the maximum likelihood estimator only for Gaussian-distributed data. Non-linear least squares methods may be applied to event counting histograms in cases where the number of events is very large, so that the Poisson distribution is well approximated by a Gaussian. However, it is not easy to satisfy this criterion in practice - which requires a large number of events. It has been well-known for years that least squares procedures lead to biased results when applied to Poisson-distributed data; a recent paper providing extensive characterization of these biases in exponential fitting is given. The more appropriate measure based on the maximum likelihood estimator (MLE
Efficient Levenberg-Marquardt minimization of the maximum likelihood estimator for Poisson deviates
Laurence, T; Chromy, B
2009-11-10
Histograms of counted events are Poisson distributed, but are typically fitted without justification using nonlinear least squares fitting. The more appropriate maximum likelihood estimator (MLE) for Poisson distributed data is seldom used. We extend the use of the Levenberg-Marquardt algorithm commonly used for nonlinear least squares minimization for use with the MLE for Poisson distributed data. In so doing, we remove any excuse for not using this more appropriate MLE. We demonstrate the use of the algorithm and the superior performance of the MLE using simulations and experiments in the context of fluorescence lifetime imaging. Scientists commonly form histograms of counted events from their data, and extract parameters by fitting to a specified model. Assuming that the probability of occurrence for each bin is small, event counts in the histogram bins will be distributed according to the Poisson distribution. We develop here an efficient algorithm for fitting event counting histograms using the maximum likelihood estimator (MLE) for Poisson distributed data, rather than the non-linear least squares measure. This algorithm is a simple extension of the common Levenberg-Marquardt (L-M) algorithm, is simple to implement, quick and robust. Fitting using a least squares measure is most common, but it is the maximum likelihood estimator only for Gaussian-distributed data. Non-linear least squares methods may be applied to event counting histograms in cases where the number of events is very large, so that the Poisson distribution is well approximated by a Gaussian. However, it is not easy to satisfy this criterion in practice - which requires a large number of events. It has been well-known for years that least squares procedures lead to biased results when applied to Poisson-distributed data; a recent paper providing extensive characterization of these biases in exponential fitting is given. The more appropriate measure based on the maximum likelihood estimator (MLE
Izumida, Yuki; Okuda, Koji
2014-05-01
We formulate the work output and efficiency for linear irreversible heat engines working between a finite-sized hot heat source and an infinite-sized cold heat reservoir until the total system reaches the final thermal equilibrium state with a uniform temperature. We prove that when the heat engines operate at the maximum power under the tight-coupling condition without heat leakage the work output is just half of the exergy, which is known as the maximum available work extracted from a heat source. As a consequence, the corresponding efficiency is also half of its quasistatic counterpart.
Maheshwari, Govind; Chaudhary, S; Somani, S.K
2010-01-01
The efficient power, defined as the product of power output and efficiency of the engine, is taken as the objective for performance analysis and optimization of an endoreversible combined Carnot heat...
Sheng, Shiqi; Tu, Z C
2015-02-01
We present a unified perspective on nonequilibrium heat engines by generalizing nonlinear irreversible thermodynamics. For tight-coupling heat engines, a generic constitutive relation for nonlinear response accurate up to the quadratic order is derived from the stalling condition and the symmetry argument. By applying this generic nonlinear constitutive relation to finite-time thermodynamics, we obtain the necessary and sufficient condition for the universality of efficiency at maximum power, which states that a tight-coupling heat engine takes the universal efficiency at maximum power up to the quadratic order if and only if either the engine symmetrically interacts with two heat reservoirs or the elementary thermal energy flowing through the engine matches the characteristic energy of the engine. Hence we solve the following paradox: On the one hand, the quadratic term in the universal efficiency at maximum power for tight-coupling heat engines turned out to be a consequence of symmetry [Esposito, Lindenberg, and Van den Broeck, Phys. Rev. Lett. 102, 130602 (2009); Sheng and Tu, Phys. Rev. E 89, 012129 (2014)]; On the other hand, typical heat engines such as the Curzon-Ahlborn endoreversible heat engine [Curzon and Ahlborn, Am. J. Phys. 43, 22 (1975)] and the Feynman ratchet [Tu, J. Phys. A 41, 312003 (2008)] recover the universal efficiency at maximum power regardless of any symmetry.
Li, Yonghui; Wu, Qiuwei; Zhu, Haiyu
2015-01-01
Based on the benchmark solid oxide fuel cell (SOFC) dynamic model for power system studies and the analysis of the SOFC operating conditions, the nonlinear programming (NLP) optimization method was used to determine the maximum electrical efficiency of the grid-connected SOFC subject...
Boiroux, Dimitri; Juhl, Rune; Madsen, Henrik;
2016-01-01
This paper addresses maximum likelihood parameter estimation of continuous-time nonlinear systems with discrete-time measurements. We derive an efficient algorithm for the computation of the log-likelihood function and its gradient, which can be used in gradient-based optimization algorithms...
Bergboer, N.H; Verdult, V.; Verhaegen, M.H.G.
2002-01-01
We present a numerically efficient implementation of the nonlinear least squares and maximum likelihood identification of multivariable linear time-invariant (LTI) state-space models. This implementation is based on a local parameterization of the system and a gradient search in the resulting parame
Maximum efficiency of steady-state heat engines at arbitrary power.
Ryabov, Artem; Holubec, Viktor
2016-05-01
We discuss the efficiency of a heat engine operating in a nonequilibrium steady state maintained by two heat reservoirs. Within the general framework of linear irreversible thermodynamics we derive a universal upper bound on the efficiency of the engine operating at arbitrary fixed power. Furthermore, we show that a slight decrease of the power below its maximal value can lead to a significant gain in efficiency. The presented analysis yields the exact expression for this gain and the corresponding upper bound.
Ortega-Casanova, Joaquin; Fernandez-Feria, Ramon
2015-11-01
The thrust generated by two heaving plates in tandem is analysed for two particular sets of configurations of interest in forward flight: a plunging leading plate with the trailing plate at rest, and the two plates heaving with the same frequency and amplitude, but varying the phase difference. The thrust efficiency of the leading plate is augmented in relation to a single plate heaving with the same frequency and amplitude in most cases. In the first configuration, we characterize the range of nondimensional heaving frequencies and amplitudes of the leading plate for which the stationary trailing plate contributes positively to the global thrust. The maximum global thrust efficiency, reached for an advance ratio slightly less than unity and a reduced frequency close to 5, is about the same as the maximum efficiency for an isolated plate. But for low frequencies the tandem configuration with the trailing plate at rest is more thrust efficient than the isolated plate. In the second configuration, we find that the maximum thrust efficiency is reached for a phase lag of 180o (counterstroking), particularly for an advance ratio unity and a reduced frequency 4.4, and it is practically the same as in the other configuration and that for a single plate. Supported by the Ministerio de Economía y Competitividad of Spain Grant no. DPI2013-40479-P.
Increasing the production efficiency and reducing the environmental impacts of hydraulic fracturing
Viswanathan, H. S.
2016-12-01
Shale gas is an unconventional fossil energy resource profoundly impacting US energy independence and is projected to last for at least 100 years. Production of methane and other hydrocarbons from low permeability shale involves hydraulic fracturing of rock, establishing fracture connectivity, and multiphase fluid-flow and reaction processes all of which are poorly understood. The result is inefficient extraction with many environmental concerns. A science-based capability is required to quantify the governing mesoscale fluid-solid interactions, including microstructural control of fracture patterns and the interaction of engineered fluids with hydrocarbon flow. These interactions depend on coupled thermo-hydro-mechanical-chemical (THMC) processes over scales from microns to tens of meters. Determining the key mechanisms in subsurface THMC systems has been impeded due to the lack of sophisticated experimental methods to measure fracture aperture and connectivity, multiphase permeability, and chemical exchange capacities at the high temperature, pressure, and stresses present in the subsurface. In this study, we developed and prototyped the microfluidic and triaxial core flood experiments required to reveal the fundamental dynamics of fracture-fluid interactions. The goal is transformation of hydraulic fracturing from present ad hoc approaches to science-based strategies while safely enhancing production. Specifically, we have demonstrated an integrated experimental/modeling approach that allows for a comprehensive characterization of fluid-solid interactions and develop models that can be used to determine the reservoir operating conditions necessary to gain a degree of control over fracture generation, fluid flow, and interfacial processes over a range of subsurface conditions.
Ruslana Sushko
2015-08-01
Full Text Available Purpose: to identify the factors of efficiency of competitive activity of highly skilled basketball players at the stage of maximum realization of individual potential. Material and Methods: in order to identify the factors that have supported the performance of Ukraine's male national team in the European Championship, data analysis and generalization of scientific and technical literature and online data, analysis of official protocols of competitive activities, analysis and generalization of best pedagogical practices, pedagogical supervision, methods of mathematical statistics were used. Results: the efficiency of competitive activity of basketball players was analyzed using such indicators as team roles, won and lost matches, scored and missed points, technical, tactical and age indicators. Conclusions: the factors of efficiency of competitive activity of highly skilled basketball players at the stage of maximum realization of individual potential were identified with regard to age indicators
Zhang, Jie; Tejada-Martínez, Andrés E; Zhang, Qiong; Lei, Hongxia
2014-04-01
The capability of predicting hydraulic and disinfection efficiencies of ozone disinfection contactors is essential for evaluating existing contactors and improving future designs. Previous attempts based on ideal and non-ideal models for the hydraulics and simplified mechanisms for chemical reaction modeling have resulted in low accuracy and are restricted to contactors with simple geometries. This manuscript develops a modeling framework for the ozonation process by combining computational fluid dynamics (CFD) with a kinetics-based reaction modeling for the first time. This computational framework has been applied to the full-scale ozone contactor operated by the City of Tampa Water Department. Flow fields, residence time distribution, ozone concentration distribution, and concentration-contact time (CT) distribution within the contactor have been predicted via the computational framework. The predictions of ozone and bromate concentrations at sample points agree well with physical experimental data measured in the contactor. The predicted CT values at the contactor outlet demonstrate that the disinfection performance of the ozone contactor operated by the City of Tampa Water Department is sufficient to meet regulation requirements. The impact of seasonal flow rate change on disinfection performance is found to be significant and deserves attention during the management and operation of a water treatment plant.
Pedretti, Daniele; Masetti, Marco; Beretta, Giovanni Pietro
2017-10-01
The expected long-term efficiency of vertical cutoff walls coupled to pump-and-treat technologies to contain solute plumes in highly heterogeneous aquifers was analyzed. A well-characterized case study in Italy, with a hydrogeological database of 471 results from hydraulic tests performed on the aquifer and the surrounding 2-km-long cement-bentonite (CB) walls, was used to build a conceptual model and assess a representative remediation site adopting coupled technologies. In the studied area, the aquifer hydraulic conductivity Ka [m/d] is log-normally distributed with mean E (Ya) = 0.32 , variance σYa2 = 6.36 (Ya = lnKa) and spatial correlation well described by an exponential isotropic variogram with integral scale less than 1/12 the domain size. The hardened CB wall's hydraulic conductivity, Kw [m/d], displayed strong scaling effects and a lognormal distribution with mean E (Yw) = - 3.43 and σYw2 = 0.53 (Yw =log10Kw). No spatial correlation of Kw was detected. Using this information, conservative transport was simulated across a CB wall in spatially correlated 1-D random Ya fields within a numerical Monte Carlo framework. Multiple scenarios representing different Kw values were tested. A continuous solute source with known concentration and deterministic drains' discharge rates were assumed. The efficiency of the confining system was measured by the probability of exceedance of concentration over a threshold (C∗) at a control section 10 years after the initial solute release. It was found that the stronger the aquifer heterogeneity, the higher the expected efficiency of the confinement system and the lower the likelihood of aquifer pollution. This behavior can be explained because, for the analyzed aquifer conditions, a lower Ka generates more pronounced drawdown in the water table in the proximity of the drain and consequently a higher advective flux towards the confined area, which counteracts diffusive fluxes across the walls. Thus, a higher σYa2 results
Design, Development and Testing of a PC Based One Axis Sun Tracking System for Maximum Efficiency
Sonu AGARWAL
2011-08-01
Full Text Available The solar energy is a clean source of energy and the photo-voltaic (PV solar panel converts the solar radiation into voltage. The PV solar panel produces the maximum power when the incident angle of sunlight is 90°. In the present paper a PC based one axis sun tracking system has been described to keep the PV solar panel perpendicular to the incident sunlight and thus to have maximum solar power utilization. A computer controlled stepper motor has been used in the tracking system to provide motion to the photovoltaic panel. LDR has been used as photo sensor to sense the incident solar radiation. The implementation of the system has been realized by designing optical to electrical signal conversion circuit, analog to digital conversion circuit, motor driving circuit and parallel port interfacing with PC. Experimental results are also included in order to validate the system performance.
Ruikun Mai
2017-02-01
Full Text Available One of the most promising inductive power transfer applications is the wireless power supply for locomotives which may cancel the need for pantographs. In order to meet the dynamic and high power demands of wireless power supplies for locomotives, a relatively long transmitter track and multiple receivers are usually adopted. However, during the dynamic charging, the mutual inductances between the transmitter and receivers vary and the load of the locomotives also changes randomly, which dramatically affects the system efficiency. A maximum efficiency point tracking control scheme is proposed to improve the system efficiency against the variation of the load and the mutual inductances between the transmitter and receivers while considering the cross coupling between receivers. Firstly, a detailed theoretical analysis on dual receivers is carried out. Then a control scheme with three control loops is proposed to regulate the receiver currents to be the same, to regulate the output voltage and to search for the maximum efficiency point. Finally, a 2 kW prototype is established to validate the performance of the proposed method. The overall system efficiency (DC-DC efficiency reaches 90.6% at rated power and is improved by 5.8% with the proposed method under light load compared with the traditional constant output voltage control method.
INVESTIGATION OF VEHICLE WHEEL ROLLING WITH MAXIMUM EFFICIENCY IN THE BRAKE MODE
D. Leontev
2011-01-01
Full Text Available Up-to-date vehicles are equipped by various systems of braking effort automatic control theparameters calculation of which do not as a rule have a rational solution. In order to increase theworking efficiency of such systems it is necessary to have the data concerning the impact of variousoperational factors on processes occurring at braking of the object of adjustment (vehicle wheel.Data availability concerning the impact of operational factors allows to decrease geometricalparameters of adjustment devices (modulators and maintain their efficient operation under variousexploitation conditions of vehicle’s motion.
Maximum-Likelihood Detection for Energy-Efficient Timing Acquisition in NB-IoT
2016-01-01
Initial timing acquisition in narrow-band IoT (NB-IoT) devices is done by detecting a periodically transmitted known sequence. The detection has to be done at lowest possible latency, because the RF-transceiver, which dominates downlink power consumption of an NB-IoT modem, has to be turned on throughout this time. Auto-correlation detectors show low computational complexity from a signal processing point of view at the price of a higher detection latency. In contrast a maximum likelihood cro...
Giuseppina Garofalo
2016-01-01
Full Text Available In an urban environment, green roofs represent a sustainable solution for mitigating stormwater volumes and hydrograph peaks. So far, many literature studies have investigated the hydraulic efficiency and the subsurface runoff coefficient of green roofs, showing their strong variability according to several factors, including the characteristics of storm events. Furthermore, only few studies have focused on the hydraulic efficiency of green roofs under Mediterranean climate conditions and defined the influencing hydrological parameters on the subsurface runoff coefficient. Nevertheless, for designing purposes, it is crucial to properly assess the subsurface runoff coefficient of a given green roof under specific climate conditions and its influencing factors. This study intends to, firstly, evaluate the subsurface runoff coefficient at daily and event-time scales for a given green roof, through a conceptual model implemented in SWMM. The model was loaded with both daily and 1-min rainfall data from two Mediterranean climate sites, one in Thessaloniki, Greece and one in Cosenza, Italy, respectively. Then, the most influencing hydrological parameters were examined through a statistical regression analysis. The findings show that the daily subsurface runoff coefficient is 0.70 for both sites, while the event-based one is 0.79 with a standard deviation of 0.23 for the site in Cosenza, Italy. The multiple linear regression analysis revealed that the influencing parameters are the rainfall intensity and antecedent dry weather period with a confidence level of 95%. This study demonstrated that, due to the high variability of the subsurface runoff coefficient, the use of a unique value for design purposes is inappropriate and that a preliminary estimation could be obtained as a function of the total rainfall depth and the antecedent dry weather period by using the validated multi-regression relationship which is site specific.
Toward Improved Rotor-Only Axial Fans—Part II: Design Optimization for Maximum Efficiency
Sørensen, Dan Nørtoft; Thompson, M. C.; Sørensen, Jens Nørkær
2000-01-01
Numerical design optimization of the aerodynamic performance of axial fans is carried out, maximizing the efficiency in a designinterval of flow rates. Tip radius, number of blades, and angular velocity of the rotor are fixed, whereas the hub radius andspanwise distributions of chord length...
Efficient strategies for genome scanning using maximum-likelihood affected-sib-pair analysis
Holmans, P.; Craddock, N. [Univ. of Wales College of Medicine, Cardiff (United Kingdom)
1997-03-01
Detection of linkage with a systematic genome scan in nuclear families including an affected sibling pair is an important initial step on the path to cloning susceptibility genes for complex genetic disorders, and it is desirable to optimize the efficiency of such studies. The aim is to maximize power while simultaneously minimizing the total number of genotypings and probability of type I error. One approach to increase efficiency, which has been investigated by other workers, is grid tightening: a sample is initially typed using a coarse grid of markers, and promising results are followed up by use of a finer grid. Another approach, not previously considered in detail in the context of an affected-sib-pair genome scan for linkage, is sample splitting: a portion of the sample is typed in the screening stage, and promising results are followed up in the whole sample. In the current study, we have used computer simulation to investigate the relative efficiency of two-stage strategies involving combinations of both grid tightening and sample splitting and found that the optimal strategy incorporates both approaches. In general, typing half the sample of affected pairs with a coarse grid of markers in the screening stage is an efficient strategy under a variety of conditions. If Hardy-Weinberg equilibrium holds, it is most efficient not to type parents in the screening stage. If Hardy-Weinberg equilibrium does not hold (e.g., because of stratification) failure to type parents in the first stage increases the amount of genotyping required, although the overall probability of type I error is not greatly increased, provided the parents are used in the final analysis. 23 refs., 4 figs., 5 tabs.
Richards, V. M.; Dai, W.
2014-01-01
A MATLAB toolbox for the efficient estimation of the threshold, slope, and lapse rate of the psychometric function is described. The toolbox enables the efficient implementation of the updated maximum-likelihood (UML) procedure. The toolbox uses an object-oriented architecture for organizing the experimental variables and computational algorithms, which provides experimenters with flexibility in experimental design and data management. Descriptions of the UML procedure and the UML Toolbox are provided, followed by toolbox use examples. Finally, guidelines and recommendations of parameter configurations are given. PMID:24671826
Shen, Yi; Dai, Wei; Richards, Virginia M
2015-03-01
A MATLAB toolbox for the efficient estimation of the threshold, slope, and lapse rate of the psychometric function is described. The toolbox enables the efficient implementation of the updated maximum-likelihood (UML) procedure. The toolbox uses an object-oriented architecture for organizing the experimental variables and computational algorithms, which provides experimenters with flexibility in experimental design and data management. Descriptions of the UML procedure and the UML Toolbox are provided, followed by toolbox use examples. Finally, guidelines and recommendations of parameter configurations are given.
Ncube, Philani; Pidou, Marc; Stephenson, Tom; Jefferson, Bruce; Jarvis, Peter
2016-12-15
It is well known that filtration removal efficiency falls with an increase in flow rate; however, there is limited supporting experimental data on how removal efficiency changes for filters with multiple layers of media and for wastewater filtration, a practice that is becoming more common. Furthermore, information is not available on the characteristics of particles that are removed at different flow rates. Here, a quadruple media filter was operated at hydraulic loading rates (HLRs) between 5 and 60 mh(-1) with subsequent measurement of total suspended solids, turbidity and particle size distribution (PSD). Samples were collected from the filter influent, effluent and also from between media layers. Pressure changes across the filter layers were also measured. The solids removal efficiency of the filter varied inversely with the increase in filtration rate. However, the multiple media layers reduced the negative impact of increased HLR in comparison to a single media filter. High filtration rates were shown to transport solids, such that particle retention and headloss development was distributed across the entire depth of the multi-media filter. There was also a progressive decrease in the suspension particle size leaving each of the filter layers. The particle hydrodynamic force simulation was consistent with the changes in measured PSD through the filter layers.
Sung Kim
2014-01-01
Full Text Available This paper describes a numerical study on the improvement of suction performance and hydraulic efficiency of a mixed-flow pump by impellers. The design of these impellers was optimized using a commercial CFD (computational fluid dynamics code and DOE (design of experiments. The design variables of meridional plane and vane plane development were defined for impeller design. In DOE, variables of inlet part were selected as main design variables in meridional plane, and incidence angle was selected in vane plane development. The verification of the experiment sets that were generated by 2k factorial was done by numerical analysis. The objective functions were defined as the NPSHre (net positive suction head required, total efficiency, and total head of the impellers. The importance of the geometric design variables was analyzed using 2k factorial designs. The interaction between the NPSHre and total efficiency, according to the meridional plane and incidence angle, was discussed by analyzing the 2k factorial design results. The performance of optimally designed model was verified by experiments and numerical analysis and the reliability of the model was retained by comparison of numerical analysis and comparative analysis with the reference model.
Maximum Efficiency of Thermoelectric Heat Conversion in High-Temperature Power Devices
V. I. Khvesyuk
2016-01-01
Full Text Available Modern trends in development of aircraft engineering go with development of vehicles of the fifth generation. The features of aircrafts of the fifth generation are motivation to use new high-performance systems of onboard power supply. The operating temperature of the outer walls of engines is of 800–1000 K. This corresponds to radiation heat flux of 10 kW/m2 . The thermal energy including radiation of the engine wall may potentially be converted into electricity. The main objective of this paper is to analyze if it is possible to use a high efficiency thermoelectric conversion of heat into electricity. The paper considers issues such as working processes, choice of materials, and optimization of thermoelectric conversion. It presents the analysis results of operating conditions of thermoelectric generator (TEG used in advanced hightemperature power devices. A high-temperature heat source is a favorable factor for the thermoelectric conversion of heat. It is shown that for existing thermoelectric materials a theoretical conversion efficiency can reach the level of 15–20% at temperatures up to 1500 K and available values of Ioffe parameter being ZT = 2–3 (Z is figure of merit, T is temperature. To ensure temperature regime and high efficiency thermoelectric conversion simultaneously it is necessary to have a certain match between TEG power, temperature of hot and cold surfaces, and heat transfer coefficient of the cooling system. The paper discusses a concept of radiation absorber on the TEG hot surface. The analysis has demonstrated a number of potentialities for highly efficient conversion through using the TEG in high-temperature power devices. This work has been implemented under support of the Ministry of Education and Science of the Russian Federation; project No. 1145 (the programme “Organization of Research Engineering Activities”.
Thien-Tong Nguyen; Doyoung Byun
2008-01-01
In the "modified quasi-steady" approach, two-dimensional (2D) aerodynamic models of flapping wing motions are analyzed with focus on different types of wing rotation and different positions of rotation axis to explain the force peak at the end of each half stroke. In this model, an additional velocity of the mid chord position due to rotation is superimposed on the translational relative velocity of air with respect to the wing. This modification produces augmented forces around the end of eachstroke. For each case of the flapping wing motions with various combination of controlled translational and rotational velocities of the wing along inclined stroke planes with thin figure-of-eight trajectory, discussions focus on lift-drag evolution during one stroke cycle and efficiency of types of wing rotation. This "modified quasi-steady" approach provides a systematic analysis of various parameters and their effects on efficiency of flapping wing mechanism. Flapping mechanism with delayed rotation around quarter-chord axis is an efficient one and can be made simple by a passive rotation mechanism so that it can be useful for robotic application.
Efficient and exact maximum likelihood quantisation of genomic features using dynamic programming.
Song, Mingzhou; Haralick, Robert M; Boissinot, Stéphane
2010-01-01
An efficient and exact dynamic programming algorithm is introduced to quantise a continuous random variable into a discrete random variable that maximises the likelihood of the quantised probability distribution for the original continuous random variable. Quantisation is often useful before statistical analysis and modelling of large discrete network models from observations of multiple continuous random variables. The quantisation algorithm is applied to genomic features including the recombination rate distribution across the chromosomes and the non-coding transposable element LINE-1 in the human genome. The association pattern is studied between the recombination rate, obtained by quantisation at genomic locations around LINE-1 elements, and the length groups of LINE-1 elements, also obtained by quantisation on LINE-1 length. The exact and density-preserving quantisation approach provides an alternative superior to the inexact and distance-based univariate iterative k-means clustering algorithm for discretisation.
Aragon-Gonzalez, G; Leon-Galicia, A; Morales-Gomez, J R
2007-01-01
In this work we include, for the Carnot cycle, irreversibilities of linear finite rate of heat transferences between the heat engine and its reservoirs, heat leak between the reservoirs and internal dissipations of the working fluid. A first optimization of the power output, the efficiency and ecological function of an irreversible Carnot cycle, with respect to: internal temperature ratio, time ratio for the heat exchange and the allocation ratio of the heat exchangers; is performed. For the second and third optimizations, the optimum values for the time ratio and internal temperature ratio are substituted into the equation of power and, then, the optimizations with respect to the cost and effectiveness ratio of the heat exchangers are performed. Finally, a criterion of partial optimization for the class of irreversible Carnot engines is herein presented.
Quantum Coherent Three-Terminal Thermoelectrics: Maximum Efficiency at Given Power Output
Robert S. Whitney
2016-05-01
Full Text Available This work considers the nonlinear scattering theory for three-terminal thermoelectric devices used for power generation or refrigeration. Such systems are quantum phase-coherent versions of a thermocouple, and the theory applies to systems in which interactions can be treated at a mean-field level. It considers an arbitrary three-terminal system in any external magnetic field, including systems with broken time-reversal symmetry, such as chiral thermoelectrics, as well as systems in which the magnetic field plays no role. It is shown that the upper bound on efficiency at given power output is of quantum origin and is stricter than Carnot’s bound. The bound is exactly the same as previously found for two-terminal devices and can be achieved by three-terminal systems with or without broken time-reversal symmetry, i.e., chiral and non-chiral thermoelectrics.
Hapenciuc, C. L.; Borca-Tasciuc, T.; Mihailescu, I. N.
2017-04-01
Thermoelectric materials are used today in thermoelectric devices for heat to electricity(thermoelectric generators-TEG) or electricity to heat(heat pumps) conversion in a large range of applications. In the case of TEGs the final measure of their performance is given by a quantity named the maximum efficiency which shows how much from the heat input is converted into electrical power. Therefore it is of great interest to know correctly how much is the efficiency of a device to can make commercial assessments. The concept of engineering figure of merit, Zeng, and engineering power factor, Peng, were already introduced in the field to quantify the efficiency of a single material under temperature dependent thermoelectric properties, with the mention that the formulas derivation was limited to one leg of the thermoelectric generator. In this paper we propose to extend the concept of engineering figure of merit to a thermoelectric generator by introducing a more general concept of device engineering thermoelectric figure of merit, Zd,eng, which depends on the both TEG materials properties and which shall be the right quantity to be used when we are interested in the evaluation of the efficiency. Also, this work takes into account the electrical contact resistance between the electrodes and thermoelement legs in an attempt to quantify its influence upon the performance of a TEG. Finally, a new formula is proposed for the maximum efficiency of a TEG.
Optimizing WiMAX: Mitigating Co-Channel Interference for Maximum Spectral Efficiency
ABDUL QADIR ANSARI
2016-10-01
Full Text Available The efficient use of radio spectrum is one of the most important issues in wireless networks because spectrum is generally limited and wireless environment is constrained to channel interference. To cope up and for increased usefulness of radio spectrum wireless networks use frequency reuse technique. The frequency reuse technique allows the use of same frequency band in different cells of same network considering inter-cell distance and resulting interference level. WiMAX (Worldwide Interoperability for Microwave Access PHY profile is designed to use FRF (Frequency Reuse Factor of one. When FRF of one is used it results in an improved spectral efficacy but also results in CCI (Co-Channel interference at cell boundaries. The effect of interference is always required to be measured so that some averaging/ minimization techniques may be incorporated to keep the interference level up to some acceptable threshold in wireless environment. In this paper, we have analyzed, that how effectively CCI impact can be mitigated by using different subcarrier permutation types presented in IEEE 802.16 standard. A simulation based analysis is presented wherein impact of using same and different permutation base in adjacent cells in a WiMAX network on CCI, under varying load conditions is analyzed. We have further studied the effect of permutation base in environment where frequency reuse technique is used in conjunction with cell sectoring for better utilization of radio spectrum.
Higuita Cano, Mauricio; Mousli, Mohamed Islam Aniss; Kelouwani, Sousso; Agbossou, Kodjo; Hammoudi, Mhamed; Dubé, Yves
2017-03-01
This work investigates the design and validation of a fuel cell management system (FCMS) which can perform when the fuel cell is at water freezing temperature. This FCMS is based on a new tracking technique with intelligent prediction, which combined the Maximum Efficiency Point Tracking with variable perturbation-current step and the fuzzy logic technique (MEPT-FL). Unlike conventional fuel cell control systems, our proposed FCMS considers the cold-weather conditions, the reduction of fuel cell set-point oscillations. In addition, the FCMS is built to respond quickly and effectively to the variations of electric load. A temperature controller stage is designed in conjunction with the MEPT-FL in order to operate the FC at low-temperature values whilst tracking at the same time the maximum efficiency point. The simulation results have as well experimental validation suggest that propose approach is effective and can achieve an average efficiency improvement up to 8%. The MEPT-FL is validated using a Proton Exchange Membrane Fuel Cell (PEMFC) of 500 W.
Amauris Gilbert-Hernández
2016-05-01
Full Text Available A procedure for the selection of maximum pipe thickness to achieve efficient thermal insulation in piping with steam tracing was developed. The bibliographical review allowed identifying the limitations of previous investigations with regard to the selection of pipe thickness in transfer systems with steam tracing. The model for calculating the overall lost heat was prepared. The procedure considers economic criteria for the selection of pipe thickness and established an optimal thickness value which guarantees a total minimum cost by establishing a balance between the expenditures resulting from heat loss and the project costs.
David S. Schechter
2005-09-28
The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, we divided the report into two chapters. The first chapter was to image and perform experimental investigation of transfer mechanisms during CO{sub 2} flooding in NFR and HFR using X-ray CT scanner. In this chapter, we emphasized our work on understanding the connection between fracture properties and fundamentals of transfer mechanism from matrix to fractures and fluid flow through fracture systems. We started our work by investigating the effect of different overburden pressures and stress-state conditions on rock properties and fluid flow. Since the fracture aperture is one of important parameter that governs the fluid flow through the fracture systems, the average fracture aperture from the fluid flow experiments and fracture aperture distribution derived from X-ray CT scan were estimated for our modeling purposes. The fracture properties and fluid flow have significant changes in response to different overburden pressures and stress-state conditions. The fracture aperture distribution follows lognormal distribution even at elevated stress conditions. Later, we also investigated the fluid transfers between matrix and fracture that control imbibition process. We evaluated dimensionless time for validating the scheme of upscaling laboratory experiments to field dimensions. In CO{sub 2} injection experiments, the use of X-ray CT has allowed us to understand the mechanisms of CO{sub 2} flooding process in fractured system and to take important steps in reducing oil bypassed. When CO{sub 2} flooding experiments were performed on a short core with a fracture at the center of the core, the gravity plays an important role in the recovery of oil
Nimo, Antwi; Grgic, Dario; Reindl, Leonhard M.
2012-04-01
This work presents the optimization of radio frequency (RF) to direct current (DC) circuits using Schottky diodes for remote wireless energy harvesting applications. Since different applications require different wireless RF to DC circuits, RF harvesters are presented for different applications. Analytical parameters influencing the sensitivity and efficiency of the circuits are presented. Results showed in this report are analytical, simulated and measured. The presented circuits operate around the frequency 434 MHz. The result of an L-matched RF to DC circuit operates at a maximum efficiency of 27 % at -35 dBm input. The result of a voltage multiplier achieves an open circuit voltage of 6 V at 0 dBm input. The result of a broadband circuit with a frequency band of 300 MHz, achieves an average efficiency of 5 % at -30 dBm and open circuit voltage of 47 mV. A high quality factor (Q) circuit is also realized with a PI network matching for narrow band applications.
46 CFR 28.405 - Hydraulic equipment.
2010-10-01
... 46 Shipping 1 2010-10-01 2010-10-01 false Hydraulic equipment. 28.405 Section 28.405 Shipping... Operate With More Than 16 Individuals on Board § 28.405 Hydraulic equipment. (a) Each hydraulic system... than four times the system maximum operating pressure. (c) Each hydraulic system must be equipped...
MA Shou-chen; LI Feng-min; YANG Shen-jiao; LI Chun-xi; XU Bing-cheng; ZHANG Xu-cheng
2013-01-01
Two pot experiments were conducted to study the effects of root pruning at the stem elongation stage on non-hydraulic root-sourced signals (nHRS), drought tolerance and water use efficiency of winter wheat (Triticum aestivum). The root pruning significantly reduced the root weight of wheat, but had no effect on root/shoot ratio at the two tested stages. At booting stage, specific root respiration of root pruned plants was significantly higher than those with intact roots (1.06 and 0.94 mmol g-1 s-1, respectively). The soil water content (SWC) at which nHRS for root pruned plants appeared was higher and terminated lower than for intact root plants, the threshold range of nHRS was markedly greater for root pruned plants (61.1-44.6%field water capacity) than for intact root plants (57.9-46.1%field water capacity). At flowering stage, while there was no significant difference in specific root respiration. The SWCs at which nHRS appeared and terminated were both higher for root pruned plants than for intact root plants. The values of chlorophyll fluorescence parameters, i.e., the effective photosystem II quantum yield ( PS I ), the maximum photochemical efficiency of PS II (Fv/Fm), coefficient of photochemical quenching (qP), and coefficient of non-photochemical quenching (NPQ), in root pruned plants were significantly higher than in intact root plants, 7 d after withholding of water. Root pruned plants had significantly higher water use efficiency (WUE) than intact root plants in well-watered and medium drought soil, but not in severe drought condition. In addition, root pruning had no significant effect on grain yield in well-watered and medium drought soil, but significantly decreased grain yield in severe drought condition. In conclusion, the current study showed that root pruning significantly altered nHRS sensitivity and improved WUE of winter wheat in well-watered and medium drought soil, but lowered drought tolerance of winter wheat in severe drought soil. This
Mehrotra, Shakti; Prakash, O; Khan, Feroz; Kukreja, A K
2013-02-01
KEY MESSAGE : ANN-based combinatorial model is proposed and its efficiency is assessed for the prediction of optimal culture conditions to achieve maximum productivity in a bioprocess in terms of high biomass. A neural network approach is utilized in combination with Hidden Markov concept to assess the optimal values of different environmental factors that result in maximum biomass productivity of cultured tissues after definite culture duration. Five hidden Markov models (HMMs) were derived for five test culture conditions, i.e. pH of liquid growth medium, volume of medium per culture vessel, sucrose concentration (%w/v) in growth medium, nitrate concentration (g/l) in the medium and finally the density of initial inoculum (g fresh weight) per culture vessel and their corresponding fresh weight biomass. The artificial neural network (ANN) model was represented as the function of these five Markov models, and the overall simulation of fresh weight biomass was done with this combinatorial ANN-HMM. The empirical results of Rauwolfia serpentina hairy roots were taken as model and compared with simulated results obtained from pure ANN and ANN-HMMs. The stochastic testing and Cronbach's α-value of pure and combinatorial model revealed more internal consistency and skewed character (0.4635) in histogram of ANN-HMM compared to pure ANN (0.3804). The simulated results for optimal conditions of maximum fresh weight production obtained from ANN-HMM and ANN model closely resemble the experimentally optimized culture conditions based on which highest fresh weight was obtained. However, only 2.99 % deviation from the experimental values could be observed in the values obtained from combinatorial model when compared to the pure ANN model (5.44 %). This comparison showed 45 % better potential of combinatorial model for the prediction of optimal culture conditions for the best growth of hairy root cultures.
WANG Yang; TU Zhan-Chun
2013-01-01
The Carnot-like heat engines are classified into three types (normal-,sub-and,super-dissipative) according to relations between the minimum irreversible entropy production in the "isothermal" processes and the time for completing those processes.The efficiencies at maximum power of normal-,sub-and super-dissipative Carnot-like heat engines are proved to be bounded between ηc/2 and ηc/ (2-ηc),ηc/2 and ηc,0 and ηc/ (2-ηc),respectively.These bounds are also shared by linear,sub-and super-linear irreversible Carnot-like engines [Tu and Wang,Europhys.Lett.98 (2012) 40001] although the dissipative engines and the irreversible ones are inequivalent to each other.
Energy-saving Study of Excavator Based on Hydraulic Pump Efficiency%基于液压泵效率的挖掘机节能研究
吴文海; 杨宇澜; 刘桓龙; 王国志
2014-01-01
For the work characteristics of the volume adjustable hydraulic pump,its control and working principle in the hydrau-lic excavator were analyzed. And as a basis,the simulation model of a volume adjustable pump and a hydraulic excavator machine was established. The simulation results show that the discharge ratio of the volume adjustable pump is an important control parameter which can achieve a greater impact on the efficiency of a hydraulic pump. When the excavator is in the fine operation phase,a reducer is used to adjust the pump speed,and the increase of the discharge ratio can improve the efficiency of the pump,so the fuel consumption is decreased by 16.5% which improves the overall fuel efficiency.%针对变量液压泵的工作特点，分析了其在液压挖掘机中控制和工作原理，并以此为基础建立了变量泵以及液压挖掘机整机的仿真模型。仿真结果表明：变量泵的排量比是对挖掘机中液压泵效率影响较大且可实现控制的一个重要参数，在挖掘机精细作业时采用减速机调节泵的转速，适当增大泵的排量比能提高泵的效率，使油耗量下降了16.5％，提高了整机的燃油效率。
Technologies and Innovations for Hydraulic Pumps
Ivantysynova, Monika
2016-01-01
Positive displacement machines working as hydraulic pumps or hydraulic motors have always been, are and will be an essential part of any hydraulic system. Current trends and future demands on energy efficient systems will not only drastically increase the number of positive displacement machines needed for modern efficient hydraulic circuits but will significantly change the performance requirements of pumps and motors. Throttleless system configurations will change the landscape of hydraulic...
Çakir, Recep; Gidirislioglu, Ali; Çebi, Ulviye
2015-12-01
The research into the treatment of domestic wastewaters originating from Büyükdöllük village in Edirne Province was carried out over a 3 year experimental period. The wastewaters of the settlement were treated using a constructed wetland with subsurface horizontal flow, and the effects of different hydraulic loading levels on removal efficiency were studied. In order to achieve this goal, three equal chambers (ponds) of 300 m(2) each were constructed and planted with Phragmites australis. Each of the chambers was loaded with domestic wastewater with average flow discharge creating hydraulic loading rates of 0. m(3) day(-1) m(-2); 0.075 m(3) day(-1) m(-2) and 0.125 m(3) day(-1) m(-2), respectively. According to the results of the study, the inlet levels of the pollutant parameters with carbon origin in the water samples taken from the system entrance are high and the average values for three years are respectively: Biological Oxygen Demand, BOD5 -324.5 mg L(-1); Chemical Oxygen Demand, COD -484,0 mg L(-1); suspended solids (TSS) -147.3 mg L(-1) and Oil and Grease -0.123 mg L(-1). It was also determined that the removal rates of the system were closely dependent on the applied hydraulic loading levels and the highest removal rates of 64.9%, 62.5%, 86.3% and 80.34% for BOD5, COD, TSS and Oil and Grease, respectively, were determined in the pond with a hydraulic loading rate of 0.050 m(3) day(-1) m(-2). Lower removal of 57.9%, 55.5%, 81.4% and 74.5% for BOD5, COD, TSS and Oil and Grease were recorded in the pond with a hydraulic loading rate of 0.075 m(3) day(-1) m(-2); and these values were 49.1%, 47.8%, 70.9% and 62.1% for the pond with a hydraulic loading rate of 0.125 m(3) day(-1) m(-2). High removal rates were also recorded for the other investigated pollution parameters.
Iogna, Patricia A; Bucci, Sandra J; Scholz, Fabián G; Goldstein, Guillermo
2013-11-01
Phenotypic plasticity in morphophysiological leaf traits in response to wind was studied in two dominant shrub species of the Patagonian steppe, used as model systems for understanding effects of high wind speed on leaf water relations and hydraulic properties of small woody plants. Morpho-anatomical traits, hydraulic conductance and conductivity and water relations in leaves of wind-exposed and protected crown sides were examined during the summer with nearly continuous high winds. Although exposed sides of the crowns were subjected to higher wind speeds and air saturation deficits than the protected sides, leaves throughout the crown had similar minimum leaf water potential (ΨL). The two species were able to maintain homeostasis in minimum ΨL using different physiological mechanisms. Berberis microphylla avoided a decrease in the minimum ΨL in the exposed side of the crown by reducing water loss by stomatal control, loss of cell turgor and low epidermal conductance. Colliguaja integerrima increased leaf water transport efficiency to maintain transpiration rates without increasing the driving force for water loss in the wind-exposed crown side. Leaf physiological changes within the crown help to prevent the decrease of minimum ΨL and thus contribute to the maintenance of homeostasis, assuring the hydraulic integrity of the plant under unfavorable conditions. The responses of leaf traits that contribute to mechanical resistance (leaf mass per area and thickness) differed from those of large physiological traits by exhibiting low phenotypic plasticity. The results of this study help us to understand the unique properties of shrubs which have different hydraulic architecture compared to trees.
Várnai, Csilla; Burkoff, Nikolas S; Wild, David L
2013-12-10
Maximum Likelihood (ML) optimization schemes are widely used for parameter inference. They maximize the likelihood of some experimentally observed data, with respect to the model parameters iteratively, following the gradient of the logarithm of the likelihood. Here, we employ a ML inference scheme to infer a generalizable, physics-based coarse-grained protein model (which includes Go̅-like biasing terms to stabilize secondary structure elements in room-temperature simulations), using native conformations of a training set of proteins as the observed data. Contrastive divergence, a novel statistical machine learning technique, is used to efficiently approximate the direction of the gradient ascent, which enables the use of a large training set of proteins. Unlike previous work, the generalizability of the protein model allows the folding of peptides and a protein (protein G) which are not part of the training set. We compare the same force field with different van der Waals (vdW) potential forms: a hard cutoff model, and a Lennard-Jones (LJ) potential with vdW parameters inferred or adopted from the CHARMM or AMBER force fields. Simulations of peptides and protein G show that the LJ model with inferred parameters outperforms the hard cutoff potential, which is consistent with previous observations. Simulations using the LJ potential with inferred vdW parameters also outperforms the protein models with adopted vdW parameter values, demonstrating that model parameters generally cannot be used with force fields with different energy functions. The software is available at https://sites.google.com/site/crankite/.
XU Jiabo; SHI Yonghai; ZHANG Genyu; LIU Jianzhong; ZHU Yazhu
2014-01-01
Constructed wetlands (CWs) were integrated into an indoor recirculating aquaculture system of obscure puffer (Takifugu obscurus) for effluent treatment. The effect of hydraulic loading rate (HLR) on the efficiency of effluent treatment by CWs was ex-amined for over a month. The CWs were operated under brackish conditions (salinity 7.4-7.6) at 3 different HLRs (0.762, 0.633, and 0.458 m d-1) 3 times, 10 days each. Overall, the CWs exhibited high efficiency in removal of total ammonium nitrogen (by 81.03-92.81%) and nitrite nitrogen (by 99.40%-99.68%). The efficiency of CWs in removal of total ammonium nitrogen, nitrate nitrogen, total Kjeldahl nitrogen, total phosphorous, and total suspended solids (TSS) increased with the decrease of HLR. The CWs operated at the 3 HLRs in a decreasing trend proves to be effective, providing a useful method for effluent treatment in commercial puffer aquaculture systems.
DeVore, Matthew S; Gull, Stephen F; Johnson, Carey K
2012-04-05
We describe a method for analysis of single-molecule Förster resonance energy transfer (FRET) burst measurements using classic maximum entropy. Classic maximum entropy determines the Bayesian inference for the joint probability describing the total fluorescence photons and the apparent FRET efficiency. The method was tested with simulated data and then with DNA labeled with fluorescent dyes. The most probable joint distribution can be marginalized to obtain both the overall distribution of fluorescence photons and the apparent FRET efficiency distribution. This method proves to be ideal for determining the distance distribution of FRET-labeled biomolecules, and it successfully predicts the shape of the recovered distributions.
Chen, Sheng-Hong
2015-01-01
This book discusses in detail the planning, design, construction and management of hydraulic structures, covering dams, spillways, tunnels, cut slopes, sluices, water intake and measuring works, ship locks and lifts, as well as fish ways. Particular attention is paid to considerations concerning the environment, hydrology, geology and materials etc. in the planning and design of hydraulic projects. It also considers the type selection, profile configuration, stress/stability calibration and engineering countermeasures, flood releasing arrangements and scouring protection, operation and maintenance etc. for a variety of specific hydraulic structures. The book is primarily intended for engineers, undergraduate and graduate students in the field of civil and hydraulic engineering who are faced with the challenges of extending our understanding of hydraulic structures ranging from traditional to groundbreaking, as well as designing, constructing and managing safe, durable hydraulic structures that are economical ...
Wiegand, D.E.
1962-05-01
A hydraulic servo is designed in which a small pressure difference produced at two orifices by an electrically operated flapper arm in a constantly flowing hydraulic loop is hydraulically amplified by two constant flow pumps, two additional orifices, and three unconnected ball pistons. Two of the pistons are of one size and operate against the additional orifices, and the third piston is of a different size and operates between and against the first two pistons. (AEC)
Hong, Yeh-Sun; Lee, Sang-Yul
2008-02-01
The internal parts of hydraulic pumps operating at variable speed should be protected from insufficient lubrication. The axial piston type pumps employ a steel-base cylinder barrel rotating on a soft bronze valves plate with a slide contact, where the insufficient lubrication of these components can cause rapid wear of the valve plate and increase the friction loss. In this study, the cylinder barrel surface was deposited with CrZrN coatings, which were expected to improve the tribological contact with a valve plate under low-speed mixed lubrication conditions. Its effect on the improvement of the low-speed torque efficiency of a hydraulic piston pump was investigated and compared with that from the CrSiN coating. The coated cylinder barrels showed much lower friction coefficients and wear rates of the valve plates than the uncoated plasma-nitride one. In particular, the CrZrN coatings revealed better performance than the CrSiN coatings. By representing the improvement in the torque efficiency of the whole pump based upon the degree of the friction coefficient reduction, the CrZrN coatings exhibited approximately a 0.35% higher improvement at 300 bar and 100 rpm than CrSiN coatings. The possible failure modes of the coatings coated on the barrel were sugested and the microstructures of the coatings seemed to have a strong effect on the film failure mode.
Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves
HUANG, Ye; Liu, Changsheng; Shiongur Bamed
2014-01-01
Hydraulic control systems of butterfly valves are presently valve-controlled and pump-controlled. Valve-controlled hydraulic systems have serious power loss and generate much heat during throttling. Pump-controlled hydraulic systems have no overflow or throttling losses but are limited in the speed adjustment of the variable-displacement pump, generate much noise, pollute the environment, and have motor power that does not match load requirements, resulting in low efficiency under...
Dukka, Bahadur K C; Akutsu, Tatsuya; Tomita, Etsuji; Seki, Tomokazu; Fujiyama, Asao
2002-01-01
We developed maximum clique-based algorithms for spot matching for two-dimensional gel electrophoresis images, protein structure alignment and protein side-chain packing, where these problems are known to be NP-hard. Algorithms based on direct reductions to the maximum clique can find optimal solutions for instances of size (the number of points or residues) up to 50-150 using a standard PC. We also developed pre-processing techniques to reduce the sizes of graphs. Combined with some heuristics, many realistic instances can be solved approximately.
Rijmen, Frank
2009-01-01
Maximum marginal likelihood estimation of multidimensional item response theory (IRT) models has been hampered by the calculation of the multidimensional integral over the ability distribution. However, the researcher often has a specific hypothesis about the conditional (in)dependence relations among the latent variables. Exploiting these…
Boiroux, Dimitri; Juhl, Rune; Madsen, Henrik
2016-01-01
. This algorithm uses UD decomposition of symmetric matrices and the array algorithm for covariance update and gradient computation. We test our algorithm on the Lotka-Volterra equations. Compared to the maximum likelihood estimation based on finite difference gradient computation, we get a significant speedup...
O. F. Nikitin
2015-01-01
Full Text Available The article deals with the static calculations in designing a high-performance fixed fluid power drive with a single positive-displacement hydraulic motor. Designing is aimed at using a drive that is under development and yet unavailable to find and record the minimum of calculations and maximum of existing hydraulic units that enable clear and unambiguous performance, taking into consideration an available assortment of hydraulic units of hydraulic drives, to have the best efficiency.The specified power (power, moment and kinematics (linear velocity or angular velocity of rotation parameters of the output element of hydraulic motor determine the main output parameters of the hydraulic drive and the useful power of the hydraulic drive under development. The value of the overall efficiency of the hydraulic drive enables us to judge the efficiency of high-performance fixed fluid power drive.The energy analysis of a diagram of the high-performance fixed fluid power drive shows that its high efficiency is achieved when the flow rate of fluid flowing into each cylinder and the magnitude of the feed pump unit (pump are as nearly as possible.The paper considers the ways of determining the geometric parameters of working hydromotors (effective working area or working volume, which allow a selection of the pumping unit parameters. It discusses the ways to improve hydraulic drive efficiency. Using the principle of holding constant conductivity allows us to specify the values of the pressure losses in the hydraulic units used in noncatalog modes. In case of no exact matching between the parameters of existing hydraulic power modes and a proposed characteristics of the pump unit, the nearest to the expected characteristics is taken as a working version.All of the steps allow us to create the high-performance fixed fluid power drive capable of operating at the required power and kinematic parameters with high efficiency.
Smith, P D
1982-01-01
BASIC Hydraulics aims to help students both to become proficient in the BASIC programming language by actually using the language in an important field of engineering and to use computing as a means of mastering the subject of hydraulics. The book begins with a summary of the technique of computing in BASIC together with comments and listing of the main commands and statements. Subsequent chapters introduce the fundamental concepts and appropriate governing equations. Topics covered include principles of fluid mechanics; flow in pipes, pipe networks and open channels; hydraulic machinery;
Mandrone, Giuseppe; Giordano, Nicolò; Bastesen, Eivind; Wheeler, Walter; Chicco, Jessica
2017-04-01
Sustainable thermal energy production from GSHP systems is greatly dependent on the thermo-hydraulic field, yet there are few realistic case studies which capture the dynamics of such systems. Here we present initial work on the static model for one such case example. A BHE field consisting of 12 ground heat exchangers in fractured crystalline rock has been supplying thermal energy for the past 20 years to meet the heating needs of a school located in Bergen, Norway. In recent years the heat pump COP has significantly decreased, which has been ascribed to a depletion of the extractable energy surrounding the BHEs, that is, by extracting more energy in the heating season than is naturally replaced in the summer. A numerical model of the underground is constructed to show the thermal depletion and determine a sustainable thermal use of the shallow reservoir (0-200 m). At this stage, the model represents the geology and structure of the underground, which consists of metamorphic rocks of the Nordåsvatnet Complex (Minor Bergen Arc, Ordovician): amphibolites, micaschists, augen gneisses and quartz-schists depict the first 200 m below ground level. Preliminary well tests in some of these BHEs showed how complex and heterogeneous is the hydrogeological field. Some wells are clearly connected, others show hydraulic head difference of more than 15 m even though they are close by. Future flow tracer tests and down-hole fracture characterization will be carried out for in-depth representation of the flow field. Here we present and discuss laboratory thermal measurements on samples collected in the area, especially a comparison of two thermal conductivity measurement techniques. Thermal conductivity measurements were carried out with the thermal conductivity scanner by Lippmann and Rauen GbR and with the KD2 Pro by Decagon Devices. The optical scanning technology and the transient line source method were therefore compared to get the most valuable results. Electrical
王光明; 朱思洪; 史立新; 倪向东; 阮文盛; 欧阳大业
2013-01-01
In order to estimate the efficiency level of a new kind of tractor hydraulic mechanical CVT, which would provide a theoretical reference for its structural optimization and power matching, the transmission efficiency of the CVT under partial and full load working condition were studied by the methods of both simulation and experimental calibration. First, a complete CVT transmission model was built, based on the software of SimulationX, and part of the model was modified by use of the components under a signal library so as to solve the direction problem of the power flow correctly. In order to ensure the reliability of the model, eight groups of experiments were made to calibrate some of key parameters of the model, such as viscous damping and leak coefficient of the hydraulic system. The results showed that the transmission efficiency level between the simulation model and the actual physical system were enough consistent to meet the research needs after parameter calibration, and that the maximum efficiency error is about 2.4%. Secondly, by a simulation analysis of the transmission efficiency of the CVT under full load working condition, the relationship among the transmission efficiency, the engine speed, and the load torque were studied. Furthermore, a map of transmission efficiency in partial load work condition was drawn also. Finally, this paper points out that it is important that the transmission ratio of gear pair g4 before pump shaft affects the transmission efficiency. The higher the transmission ratio of the gear pair, the higher the transmission efficiency will be. But a higher transmission ratio of gear pair g4 would affect both the transmission ratio distribution of each gear and the load level of motor shaft, making the hydraulic system design and component selection difficult. The conclusion in this paper shows that the transmission efficiency of the CVT is in inverse proportion to the rotational speed of the engine and in direct proportion to
Department of Homeland Security — This table is required whenever hydraulic structures are shown in the flood profile. It is also required if levees are shown on the FIRM, channels containing the...
Kukush, Alexander; Schneeweiss, Hans
2004-01-01
We compare the asymptotic covariance matrix of the ML estimator in a nonlinear measurement error model to the asymptotic covariance matrices of the CS and SQS estimators studied in Kukush et al (2002). For small measurement error variances they are equal up to the order of the measurement error variance and thus nearly equally efficient.
Babayev, Z.B.; Abashev, Z.V.
1982-01-01
The efficiency expert of the Angrenskiy production-technological administration of the production association Sredazugol A. V. Bubnov has suggested a hydraulic hoist-press for repairing road equipment which is a device consisting of lifting mechanism, press and test stand for verifying the high pressure hoses and pumps.
Ye, Zhuo-Lin; Li, Wei-Sheng; Lai, Yi-Ming; He, Ji-Zhou; Wang, Jian-Hui
2015-12-01
We propose a quantum-mechanical Brayton engine model that works between two superposed states, employing a single particle confined in an arbitrary power-law trap as the working substance. Applying the superposition principle, we obtain the explicit expressions of the power and efficiency, and find that the efficiency at maximum power is bounded from above by the function: η+ = θ/(θ + 1), with θ being a potential-dependent exponent. Supported by the National Natural Science Foundation of China under Grant Nos. 11505091, 11265010, and 11365015, and the Jiangxi Provincial Natural Science Foundation under Grant No. 20132BAB212009
Radovcich, N. A.; Dreim, D.; Okeefe, D. A.; Linner, L.; Pathak, S. K.; Reaser, J. S.; Richardson, D.; Sweers, J.; Conner, F.
1985-01-01
Work performed in the design of a transport aircraft wing for maximum fuel efficiency is documented with emphasis on design criteria, design methodology, and three design configurations. The design database includes complete finite element model description, sizing data, geometry data, loads data, and inertial data. A design process which satisfies the economics and practical aspects of a real design is illustrated. The cooperative study relationship between the contractor and NASA during the course of the contract is also discussed.
Kaiadi, Mehrzad; Tunestål, Per; Johansson, Bengt
2010-01-01
High EGR rates combined with turbocharging has been identified as a promising way to increase the maximum load and efficiency of heavy duty spark ignition Natural Gas engines. With stoichiometric conditions a three way catalyst can be used which means that regulated emissions can be kept at very low levels. Most of the heavy duty NG engines are diesel engines which are converted for SI operation. These engine's components are in common with the diesel-engine which put limits on higher exh...
Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves
Ye HUANG
2014-09-01
Full Text Available Hydraulic control systems of butterfly valves are presently valve-controlled and pump-controlled. Valve-controlled hydraulic systems have serious power loss and generate much heat during throttling. Pump-controlled hydraulic systems have no overflow or throttling losses but are limited in the speed adjustment of the variable-displacement pump, generate much noise, pollute the environment, and have motor power that does not match load requirements, resulting in low efficiency under light loads and wearing of the variable-displacement pump. To overcome these shortcomings, this article designs a closed hydraulic control system in which an AC servo motor drives a quantitative pump that controls a spiral swinging hydraulic cylinder, and analyzes and calculates the structure and parameters of a spiral swinging hydraulic cylinder. The hydraulic system adjusts the servo motor’s speed according to the requirements of the control system, and the motor power matches the power provided to components, thus eliminating the throttling loss of hydraulic circuits. The system is compact, produces a large output force, provides stable transmission, has a quick response, and is suitable as a hydraulic control system of a large butterfly valve.
Remotely Adjustable Hydraulic Pump
Kouns, H. H.; Gardner, L. D.
1987-01-01
Outlet pressure adjusted to match varying loads. Electrohydraulic servo has positioned sleeve in leftmost position, adjusting outlet pressure to maximum value. Sleeve in equilibrium position, with control land covering control port. For lowest pressure setting, sleeve shifted toward right by increased pressure on sleeve shoulder from servovalve. Pump used in aircraft and robots, where hydraulic actuators repeatedly turned on and off, changing pump load frequently and over wide range.
Sniegowski, Kristel; Bers, Karolien; Ryckeboer, Jaak; Jaeken, Peter; Spanoghe, Pieter; Springael, Dirk
2012-08-01
Addition of pesticide-primed soil containing adapted pesticide degrading bacteria to the biofilter matrix of on farm biopurification systems (BPS) which treat pesticide contaminated wastewater, has been recommended, in order to ensure rapid establishment of a pesticide degrading microbial community in BPS. However, uncertainties exist about the minimal soil inoculum density needed for successful bioaugmentation of BPS. Therefore, in this study, BPS microcosm experiments were initiated with different linuron primed soil inoculum densities ranging from 0.5 to 50 vol.% and the evolution of the linuron mineralization capacity in the microcosms was monitored during feeding with linuron. Successful establishment of a linuron mineralization community in the BPS microcosms was achieved with all inoculum densities including the 0.5 vol.% density with only minor differences in the time needed to acquire maximum degradation capacity. Moreover, once established, the robustness of the linuron degrading microbial community towards expected stress situations proved to be independent of the initial inoculum density. This study shows that pesticide-primed soil inoculum densities as low as 0.5 vol.% can be used for bioaugmentation of a BPS matrix and further supports the use of BPS for treatment of pesticide-contaminated wastewater at farmyards.
Yang, Yongqiang; Zhan, Xuan; Wu, Shijun; Kang, Mingliang; Guo, Jianan; Chen, Fanrong
2016-04-01
The low hydraulic loading rate (HLR) greatly restricts the wide application of subsurface wastewater infiltration system (SWIS) in densely populated areas. To increase the HLR, an innovative SWIS was developed using cyclic operation mode. In each cycle, a wastewater feeding period is followed by a drying period, in which the aeration is conducted by a medium-pressure fan. Results indicated that the removal rate of TOC and NH4(+)-N were more than 85% at HLR of 0.5m(3)/m(2)d, whereas the TN removal rate was lower than 20%, indicating that the aeration was efficient and denitrification process was largely limited in the SWIS. When HLR decreased from 0.5 to 0.2m(3)/m(2)d, the pollutant removal efficiency enhanced slightly except for TN. Overall, the intermittent operation and micro-power aeration, combined with shunting the pollutant loading were really helpful for SWIS to achieve higher HLR, which offers a reference for the design of innovative SWIS.
Hydraulic hammer drilling technology: Developments and capabilities
Melamed, Y.; Kiselev, A. [SKB Geotechnika, Moscow (Russian Federation); Gelfgat, M. [Aquatic Co., Moscow (Russian Federation); Dreesen, D.; Blacic, J. [Los Alamos National Lab., NM (United States). GeoEngineering Group
1996-12-31
Percussion drilling technology was considered many years ago as one of the best approaches for hard rock drilling. Unfortunately the efficiency of most hydraulic hammer (HH) designs was very low (8% maximum), so they were successfully used in shallow boreholes only. Thirty years of research and field drilling experience with HH application in Former Soviet Union (FSU) countries led to the development of a new generation of HH designs with a proven efficiency of 40%. That advance achieved good operational results in hard rock at depths up to 2,000 m and more. The most recent research has shown that there are opportunities to increase HH efficiency up to 70%. This paper presents HH basic design principles and operational features. The advantages of HH technology for coiled-tubing drilling is shown on the basis of test results recently conducted in the US.
林躜; 李磊; 陈俊华; 郑堤; 唐辰; 李浩
2014-01-01
In order to solve the problem of low energy capturing efficiency of the horizontal axis turbine in tidal current power generation system at low current speed, a variable pump counter torque reference value model was established. In this study, based on the maximum power tracking theory and the torque equilibrium equation of turbine versus variable pump, a control system with indirect speed control, pressure feedback, and torque control was designed to achieve the maximum power capture of the turbine by regulating the output of the variable pump in a small range. The performance of the designed control system was simulated by means of the Automation Studio software, and corresponding sea test was conducted. Test results showed that the control system ran steadily, the captured power coefficient of the turbine fluctuated near 0.35 and 0.33, respectively, in the simulation and sea trials; compared with the uncontrolled, these numbers increased by 0.03 and 0.05, respectively. The capture efficiency of the turbine was enhanced, and the effectiveness of the control system was verified.%文章为解决水平轴潮流能发电系统在低于设计流速下叶轮能量捕获效率低的问题,运用最大功率跟踪控制理论及叶轮与变量泵传动轴力矩平衡方程,建立了变量泵反力矩参考值模型,设计了间接速度控制的压力反馈加转矩控制系统,通过小范围内调节变量泵排量,实现叶轮最大功率捕获。整个系统的性能在自动化工作室(automation studio)中进行了仿真测试,实验样机也进行了海上试验。仿真测试和海试结果显示,该控制系统工作稳定性好,仿真和海试时叶轮的捕获功率系数分别在0.35和0.33附近波动,相比不加控制,分别增加了约0.03和0.05,提高了叶轮的捕获效率,验证了控制系统的有效性。
Ramachandran, Hema; Pillai, K. P. P.; Bindu, G. R.
2016-08-01
A two-port network model for a wireless power transfer system taking into account the distributed capacitances using PP network topology with top coupling is developed in this work. The operating and maximum power transfer efficiencies are determined analytically in terms of S-parameters. The system performance predicted by the model is verified with an experiment consisting of a high power home light load of 230 V, 100 W and is tested for two forced resonant frequencies namely, 600 kHz and 1.2 MHz. The experimental results are in close agreement with the proposed model.
M. Girotto
2012-06-01
Full Text Available Esta pesquisa teve como objetivo avaliar a velocidade e intensidade de ação do hexazinone isolado e em mistura com outros inibidores do fotossistema II, através da eficiência fotossintética de Panicum maximum em pós-emergência. O ensaio foi constituído de seis tratamentos: hexazinone (250 g ha-1, tebuthiuron (1,0 kg ha-1, hexazinone + tebuthiuron (125 g ha-1 + 0,5 kg ha-1, diuron (2.400 g ha-1, hexazinone + diuron (125 + 1.200 g ha-1, metribuzin (1.440 g ha-1, hexazinone + metribuzin (125 + 720 g ha-1 e uma testemunha. O experimento foi instalado em delineamento inteiramente casualizado, com quatro repetições. Após a aplicação dos tratamentos, as plantas foram transportadas para casa de vegetação sob condições controladas de temperatura e umidade, onde ficaram durante o período experimental, sendo realizadas as seguintes avaliações: taxa de transporte de elétrons e análise visual de intoxicação. A avaliação com o fluorômetro foi realizada nos intervalos de 1, 2, 6, 24, 48, 72, 120 e 168 horas após a aplicação, e as avaliações visuais, aos três e sete dias após a aplicação. Os resultados demonstraram diferença nos tratamentos, enfatizando a aplicação do diuron, que reduziu lentamente o transporte de elétrons comparado com os outros herbicidas e, em mistura com hexazinone, apresentou efeito sinérgico. Verificou-se com o uso do fluorômetro a intoxicação antecipada em plantas de P. maximum após a aplicação de herbicidas inibidores do fotossistema II de forma isolada e em mistura.This work aimed to evaluate the speed and intensity of action of hexazinone applied alone and in combination with other photo-system II inhibitors on the photosynthetic efficiency of Panicum maximum in post-emergence. The assay consisted of six treatments: hexazinone (250 g ha-1, tebuthiuron (1.0 kg ha-1, hexazinone + tebuthiuron (125 g ha-1+ 0.5 kg ha-1, diuron (2,400 g ha-1, hexazinone + diuron (125 + 1,200 g ha-1, metribuzin
Basko, M. M.
2016-08-01
Theoretical investigation has been performed on the conversion efficiency (CE) into the 13.5-nm extreme ultraviolet (EUV) radiation in a scheme where spherical microspheres of tin (Sn) are simultaneously irradiated by two laser pulses with substantially different wavelengths. The low-intensity short-wavelength pulse is used to control the rate of mass ablation and the size of the EUV source, while the high-intensity long-wavelength pulse provides efficient generation of the EUV light at λ=13.5 nm. The problem of full optimization for maximizing the CE is formulated and solved numerically by performing two-dimensional radiation-hydrodynamics simulations with the RALEF-2D code under the conditions of steady-state laser illumination. It is shown that, within the implemented theoretical model, steady-state CE values approaching 9% are feasible; in a transient peak, the maximum instantaneous CE of 11.5% was calculated for the optimized laser-target configuration. The physical factors, bringing down the fully optimized steady-state CE to about one half of the absolute theoretical maximum of CE≈20 % for the uniform static Sn plasma, are analyzed in detail.
Hydraulic conductivity of compacted zeolites.
Oren, A Hakan; Ozdamar, Tuğçe
2013-06-01
Hydraulic conductivities of compacted zeolites were investigated as a function of compaction water content and zeolite particle size. Initially, the compaction characteristics of zeolites were determined. The compaction test results showed that maximum dry unit weight (γ(dmax)) of fine zeolite was greater than that of granular zeolites. The γ(dmax) of compacted zeolites was between 1.01 and 1.17 Mg m(-3) and optimum water content (w(opt)) was between 38% and 53%. Regardless of zeolite particle size, compacted zeolites had low γ(dmax) and high w(opt) when compared with compacted natural soils. Then, hydraulic conductivity tests were run on compacted zeolites. The hydraulic conductivity values were within the range of 2.0 × 10(-3) cm s(-1) to 1.1 × 10(-7) cm s(-1). Hydraulic conductivity of all compacted zeolites decreased almost 50 times as the water content increased. It is noteworthy that hydraulic conductivity of compacted zeolite was strongly dependent on the zeolite particle size. The hydraulic conductivity decreased almost three orders of magnitude up to 39% fine content; then, it remained almost unchanged beyond 39%. Only one report was found in the literature on the hydraulic conductivity of compacted zeolite, which is in agreement with the findings of this study.
Design of hydraulic output Stirling engine
Toscano, W. M.; Harvey, A. C.; Lee, K.
1983-01-01
A hydraulic output system for the RE-1000 free piston stirling engine (FPSE) was designed. The hydraulic output system can be readily integrated with the existing hot section of RE-1000 FPSE. The system has two simply supported diaphragms which separate the engine gas from the hydraulic fluid, a dynamic balance mechanism, and a novel, null center band hydraulic pump. The diaphragms are designed to endure more than 10 billion cycles, and to withstand the differential pressure load as high as 14 MPa. The projected thermodynamic performance of the hydraulic output version of RE-1000 FPSE is 1.87 kW at 29/7 percent brake efficiency.
Numerical Simulation of the Propagation of Hydraulic and Natural Fracture Using Dijkstra’s Algorithm
Yanfang Wu
2016-07-01
Full Text Available Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed on the basis of weighted fracture which is derived in combination of Dijkstra’s algorithm energy theory and vector method. Numerical results along with experimental data demonstrated that proposed method is capable of predicting the propagated hydraulic fracture configuration reasonably with high computation efficiency. Sensitivity analysis reveals a number of interesting observation results: the shortest path weight value decreases with increasing of fracture density and length, and increases with increasing of the angle between fractures to the maximum principal stress direction. Our method is helpful for evaluating the complexity of the discrete fracture network, to obtain the extension direction of the fracture.
Hydraulic constraints modify optimal photosynthetic profiles in giant sequoia trees.
Ambrose, Anthony R; Baxter, Wendy L; Wong, Christopher S; Burgess, Stephen S O; Williams, Cameron B; Næsborg, Rikke R; Koch, George W; Dawson, Todd E
2016-11-01
Optimality theory states that whole-tree carbon gain is maximized when leaf N and photosynthetic capacity profiles are distributed along vertical light gradients such that the marginal gain of nitrogen investment is identical among leaves. However, observed photosynthetic N gradients in trees do not follow this prediction, and the causes for this apparent discrepancy remain uncertain. Our objective was to evaluate how hydraulic limitations potentially modify crown-level optimization in Sequoiadendron giganteum (giant sequoia) trees up to 90 m tall. Leaf water potential (Ψ l ) and branch sap flow closely followed diurnal patterns of solar radiation throughout each tree crown. Minimum leaf water potential correlated negatively with height above ground, while leaf mass per area (LMA), shoot mass per area (SMA), leaf nitrogen content (%N), and bulk leaf stable carbon isotope ratios (δ(13)C) correlated positively with height. We found no significant vertical trends in maximum leaf photosynthesis (A), stomatal conductance (g s), and intrinsic water-use efficiency (A/g s), nor in branch-averaged transpiration (E L), stomatal conductance (G S), and hydraulic conductance (K L). Adjustments in hydraulic architecture appear to partially compensate for increasing hydraulic limitations with height in giant sequoia, allowing them to sustain global maximum summer water use rates exceeding 2000 kg day(-1). However, we found that leaf N and photosynthetic capacity do not follow the vertical light gradient, supporting the hypothesis that increasing limitations on water transport capacity with height modify photosynthetic optimization in tall trees.
Zeng, Ming; Soric, Audrey; Roche, Nicolas
2013-09-01
In this study, total organic carbon (TOC) biodegradation was simulated by GPS-X software in biofilm reactors with carriers of plastic rings and glass beads under different hydraulic conditions. Hydrodynamic model by retention time distribution and biokinetic measurement by in-situ batch test served as two significant parts of model calibration. Experimental results showed that TOC removal efficiency was stable in both media due to the enough height of column, although the actual hydraulic volume changed during the variation of hydraulic condition. Simulated TOC removal efficiencies were close to experimental ones with low theil inequality coefficient values (below 0.15). Compared with glass beads, more TOC was removed in the filter with plastic rings due to the larger actual hydraulic volume and lower half saturation coefficient in spite of its lower maximum specific growth rate of biofilm, which highlighted the importance of calibrating hydrodynamic behavior and biokinetics.
Koyama, Shinsuke; Paninski, Liam
2010-08-01
A number of important data analysis problems in neuroscience can be solved using state-space models. In this article, we describe fast methods for computing the exact maximum a posteriori (MAP) path of the hidden state variable in these models, given spike train observations. If the state transition density is log-concave and the observation model satisfies certain standard assumptions, then the optimization problem is strictly concave and can be solved rapidly with Newton-Raphson methods, because the Hessian of the loglikelihood is block tridiagonal. We can further exploit this block-tridiagonal structure to develop efficient parameter estimation methods for these models. We describe applications of this approach to neural decoding problems, with a focus on the classic integrate-and-fire model as a key example.
Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik
1997-01-01
This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application...... of the laws of physics on the system. The unknown (or uncertain) parameters are estimated with Maximum Likelihood (ML) parameter estimation. The identified model has been evaluated by comparing the measurements with simulation of the model. The identified model was much more capable of describing the dynamics...... of the system than the deterministic model....
Ogawa, Akira; Anzou, Hideki; Yamamoto, So; Shimagaki, Mituru
2015-11-01
In order to control the maximum tangential velocity Vθm(m/s) of the turbulent rotational air flow and the collection efficiency ηc (%) using the fly ash of the mean diameter XR50=5.57 µm, two secondary jet nozzles were installed to the body of the axial flow cyclone dust collector with the body diameter D1=99mm. Then in order to estimate Vθm (m/s), the conservation theory of the angular momentum flux with Ogawa combined vortex model was applied. The comparisons of the estimated results of Vθm(m/s) with the measured results by the cylindrical Pitot-tube were shown in good agreement. And also the estimated collection efficiencies ηcth (%) basing upon the cut-size Xc (µm) which was calculated by using the estimated Vθ m(m/s) and also the particle size distribution R(Xp) were shown a little higher values than the experimental results due to the re-entrainment of the collected dust. The best method for adjustment of ηc (%) related to the contribution of the secondary jet flow is principally to apply the centrifugal effect Φc (1). Above stated results are described in detail.
Kinkhabwala, Ali
2013-01-01
The most fundamental problem in statistics is the inference of an unknown probability distribution from a finite number of samples. For a specific observed data set, answers to the following questions would be desirable: (1) Estimation: Which candidate distribution provides the best fit to the observed data?, (2) Goodness-of-fit: How concordant is this distribution with the observed data?, and (3) Uncertainty: How concordant are other candidate distributions with the observed data? A simple unified approach for univariate data that addresses these traditionally distinct statistical notions is presented called "maximum fidelity". Maximum fidelity is a strict frequentist approach that is fundamentally based on model concordance with the observed data. The fidelity statistic is a general information measure based on the coordinate-independent cumulative distribution and critical yet previously neglected symmetry considerations. An approximation for the null distribution of the fidelity allows its direct conversi...
Katherine McCulloh; John S. Sperry; Barbara Lachenbruch; Frederick D. Meinzer; Peter B. Reich; Steven Voelker
2010-01-01
Coniferous, diffuse-porous and ring-porous trees vary in their xylem anatomy, but the functional consequences of these differences are not well understood from the scale of the conduit to the individual. Hydraulic and anatomical measurements were made on branches and trunks from 16 species from temperate and tropical areas, representing all three wood types. Scaling of...
High precise control method for a new type of piezoelectric electro-hydraulic servo valve
无
2007-01-01
A new type of piezoelectric electro-hydraulic servo valve system was proposed. And then multilayer piezoelectric actuator based on new piezoelectric ceramic material was used as the electricity-machine converter of the proposed piezoelectric electro-hydraulic servo valve. The proposed piezoelectric electro-hydraulic servo valve has ascendant performance compared with conventional ones. But the system is of high nonlinearity and uncertainty, it cannot achieve favorable control performance by conventional control method. To develop an efficient way to control piezoelectric electro-hydraulic servo valve system, a high-precise fuzzy control method with hysteresis nonlinear model in feedforward loop was proposed. The control method is separated into two parts: a feedforward loop with Preisach hysteresis nonlinear model and a feedback loop with high-precise fuzzy control. Experimental results show that the hysteresis loop and the maximum output hysteresis by the PID control method are 4.22%and 2.11 μm, respectively; the hysteresis loop and the maximum output hysteresis by the proposed control method respectively are 0.74% and 0.37 μm, respectively; the maximum tracking error by the PID control method for sine wave reference signal is about 5.02%, the maximum tracking error by the proposed control method for sine wave reference signal is about 0.85%.
1993-07-01
This document provides an analysis of the potential impacts associated with the proposed action, which is continued operation of Naval Petroleum Reserve No. I (NPR-1) at the Maximum Efficient Rate (MER) as authorized by Public law 94-258, the Naval Petroleum Reserves Production Act of 1976 (Act). The document also provides a similar analysis of alternatives to the proposed action, which also involve continued operations, but under lower development scenarios and lower rates of production. NPR-1 is a large oil and gas field jointly owned and operated by the federal government and Chevron U.SA Inc. (CUSA) pursuant to a Unit Plan Contract that became effective in 1944; the government`s interest is approximately 78% and CUSA`s interest is approximately 22%. The government`s interest is under the jurisdiction of the United States Department of Energy (DOE). The facility is approximately 17,409 acres (74 square miles), and it is located in Kern County, California, about 25 miles southwest of Bakersfield and 100 miles north of Los Angeles in the south central portion of the state. The environmental analysis presented herein is a supplement to the NPR-1 Final Environmental Impact Statement of that was issued by DOE in 1979 (1979 EIS). As such, this document is a Supplemental Environmental Impact Statement (SEIS).
王钊宁; 罗兴锜; 郭鹏程; 程宦; 王亚林
2015-01-01
基于海南大广坝水电站水轮机改造项目，通过分析电站运行中存在的水力不稳定现象和水轮机效率水平偏低的原因，提出了水轮机的改造方案和目标；讨论了水力参数和设计理念；介绍了改造前后转轮流道的本质差异。通过全流道数值仿真计算，定性评估了改造后水轮机的稳定性，定量标定了水轮机的效率水平，预期了模型水轮机的综合特性曲线。结论认为，改造后模型水轮机最优效率大于93．8％，额定效率91％，加权平均效率89．3％；原型水轮机最优效率95．1％，额定效率92．4％，加权平均效率90．8％；与改造前相比，加权平均效率增幅可达2．0％。%A new retrofitting method and target are presented by means of analyzing the phenome‐non of hydraulic instability and the reason of relatively low turbine efficiency based on the trans‐formation project referring to Daguangba Hydropower station in Hainan ,meanwhile ,hydraulic parameters selection and design conception are discussed in details .Also ,this paper introduces the essential difference of runner channel between pre‐and‐post retrofit .According to the full passage numerical simulation computation ,the hydraulic stability of retrofitted Francis runner is qualitatively evaluated and the efficiency level is quantitatively indicated .Finally ,the paper has predicted the comprehensive feature curves of the model water‐turbine .The conclusions indicate that the model turbine optimum efficiency exceeds 93 .8% ,the rated efficiency and weighted aver‐age efficiency are respectively 91% and 89 .3% compared with 95 .1% optimum efficiency ,92 .4%rated efficiency ,and 90 .8% weighted average efficiency originating from the prototype turbine ;the weighted average efficiency of the model turbine significantly increases 2 .0% by contrast with the one of the prototype turbine .
The 25 kWe solar thermal Stirling hydraulic engine system: Conceptual design
White, Maurice; Emigh, Grant; Noble, Jack; Riggle, Peter; Sorenson, Torvald
1988-01-01
The conceptual design and analysis of a solar thermal free-piston Stirling hydraulic engine system designed to deliver 25 kWe when coupled to a 11 meter test bed concentrator is documented. A manufacturing cost assessment for 10,000 units per year was made. The design meets all program objectives including a 60,000 hr design life, dynamic balancing, fully automated control, more than 33.3 percent overall system efficiency, properly conditioned power, maximum utilization of annualized insolation, and projected production costs. The system incorporates a simple, rugged, reliable pool boiler reflux heat pipe to transfer heat from the solar receiver to the Stirling engine. The free-piston engine produces high pressure hydraulic flow which powers a commercial hydraulic motor that, in turn, drives a commercial rotary induction generator. The Stirling hydraulic engine uses hermetic bellows seals to separate helium working gas from hydraulic fluid which provides hydrodynamic lubrication to all moving parts. Maximum utilization of highly refined, field proven commercial components for electric power generation minimizes development cost and risk.
Hydraulic fracturing system and method
Ciezobka, Jordan; Salehi, Iraj
2017-02-28
A hydraulic fracturing system and method for enhancing effective permeability of earth formations to increase hydrocarbon production, enhance operation efficiency by reducing fluid entry friction due to tortuosity and perforation, and to open perforations that are either unopened or not effective using traditional techniques, by varying a pump rate and/or a flow rate to a wellbore.
Measurement and evaluation of static characteristics of rotary hydraulic motor
Hružík Lumír
2014-03-01
Full Text Available The paper describes experimental equipment for measurement of static characteristics of rotary hydraulic motor. It is possible to measure flow, pressure, temperature, speed and torque by means of this equipment. It deals with measurement of static characteristics of a gear rotary hydraulic motor. Mineral oil is used as hydraulic liquid in this case. Flow, torque and speed characteristics are evaluated from measured parameters. Measured mechanical-hydraulic, flow and total efficiencies of the rotary hydraulic motor are adduced in the paper. It is possible to diagnose technical conditions of the hydraulic motor (eventually to recommend its exchange from the experimental measurements.
柳清; 刘文君; 高京伟; 张素霞
2009-01-01
以枯草杆菌黑色变种芽孢为目标微生物,以紫外线消毒后的炭滤池出水为进水,在中试清水池模型中模拟氯消毒过程,通过改变清水池导流板数目获得不同的水力条件,研究清水池水力条件对氯消毒效率的影响.结果表明,在本试验中,不同水力条件下以Ct_(10)值计算的NaClO对枯草杆菌黑色变种芽孢的灭活系数之间相互一致,而不同水力条件下以CT值计算的NaClO对枯草杆菌黑色变种芽孢的灭活系数之间相差很大,表明Ct_(10)是评价清水池消毒效率的合理指标;在Ct_(10)=(100～300)mg·min/L的范围内,NaClO对枯草杆菌黑色变种芽孢的灭活系数为0.001 6 L/(mg·min),与其他研究者的结果具有很好的一致性;清水池水力条件的改善可以提高消毒效率,在CT=(100～700)mg·min/L的范围内,当CT值固定时,随着清水池内导流板数增多,水力条件得到改善,t_(10)增加,目标菌种的灭活率显著提高.%A pilot clearwell was used to simulate the chlorine disinfection process with the Bacillus subtilis spores as the target microbe. The effluent of the activated carbon filter tank was radiated by low pressure UV lamp and then used as the influent the pilot clearwell. The impacts of hydraulic characteristics of pilot clearwell on disinfection efficiency of Bacillus subtilis spores was studied under different hydraulic characteristics which was changed by the number of the baffles. Under the conditions of this experiment, the inactivation coefficients of Bacillus subtilis spores with NaClO as disinfectant which were calculated by Ct_(10) value were almost same under different hydraulic characteristics, but the inactivation coefficients which were calculated by CT value were very different under different hydraulic characteristics. This verified that it was more reasonable to evaluate the disinfection efficiency by Ct_(10) value than CT value. When Ct_(10) value was in the range of 100 ～ 300 mg
唐治德; 徐阳阳; 赵茂; 彭一灵
2015-01-01
By applying lumped parameter circuit theory and coupled mode theory, the efficiency of wire-less power transfer system via magnetic resonant coupling was researched, and the concept of transfer effi-ciency maximum frequency was proposed when transfer efficiency is maximum. Influence of system pa-rameters and load on transfer efficiency maximum frequency and transfer efficiency were analyzed. Two coils transfer system was set up, and the relationship between the frequency and transfer efficiency, the relationship between load and transfer efficiency maximum frequency and between load and transfer effi-ciency were studied,and the relationship between distance and transfer efficiency maximum frequency and between distance and transfer efficiency were carried out. Experiments and simulation prove that: there is a transfer efficiency maximum frequency in wireless power transfer system; and this transfer efficiency maximum frequency is proportional to the load and inversely proportional to mutual inductance approxi-mately; transfer efficiency maximum frequency increases with the increase of distance; when the system work in transfer efficiency maximum frequency and the load resistance is much greater than the coil resist-ance, the transfer efficiency of wireless power transfer system is maximum.%应用集总参数和耦合模理论，研究了电磁耦合式无线电能传输系统的传输效率问题，提出了使无线电能传输系统传输效率最大的传输效率最佳频率概念，分析了传输系统参数和负载对传输效率最佳频率和传输效率的影响。制作了两线圈无线电能传输实验电路，并进行了谐振频率与传输效率的关系，负载与传输效率最佳频率及传输效率的关系，距离与传输效率最佳频率及传输效率的关系实验和仿真分析。实验和仿真分析证明了：无线电能传输系统有一个传输效率最佳频率；传输效率最佳频率近似与负载成正比，与线圈
Ghaniyari-Benis, Saeid; Martín, Antonio; Borja Padilla, Rafael; M. A. Martín; Hedayat, N.
2012-01-01
A modelling of the anaerobic digestion process of molasses was conducted in a 70-L multistage anaerobic biofilm reactor or hybrid anaerobic baffled reactor with six compartments at an operating temperature of 26 Â°C. Five hydraulic retention times (6, 16, 24, 72 and 120 h) were studied at a constant influent COD concentration of 10,000 mg/L. Two different kinetic models (one was based on a dispersion model with first-order kinetics for substrate consumption and the other based on a modificati...
Teodor Eugen Man
2010-01-01
Full Text Available This paper presents two examples of exploitation of water energy that can be used in the irrigation field. First of theseexamples is the hydraulic transformer type A. Barglazan used for irrigation, pumped water is taken directly from theriver’s well, using a hydraulic pump which simultaneously carried out a double transformation in this way: hydraulicenergy into mechanic energy and mechanical energy into hydraulic energy. Technology preparation and devices designwas done in record time, seeing that this constructive solution is more robust, reliable and with improved energyperformance versus the laboratory prototype. The experimental research which was made at 1:1 scale proved theirgood function over time. Another example is the hydraulic hammer (hydraulic pump that uses low-head energy topump water, with a global efficiency of about 10 - 50%. Currently, the new situation of private ownership of landprovides conditions for new pumping microstations to be made where irrigation is necessary and optimal hydrauliclocations exist.
Sun, Shuaihui; Huang, Yi; Guo, Pengcheng; Zuo, Juanli; Luo, Xingqi
2016-11-01
In the present paper, the computer fluid dynamics(CFD) with dynamic mesh model had been applied in scroll hydraulic pump to obtain its flow field at different leakage clearance. The fluid force on the orbiting scroll, the mass flow rate and the hydraulic efficiency at different leakage clearance were calculated based on the flow field data. The results indicated that when the leakage clearance increased from 0.5mm to 1.5mm, the average pressure, maximum of pressure fluctuation, leakage jet flow velocity, shaft power, cavitation degree decreased and the leakage flow rate increased. If the leakage clearance was 2.0mm, the high pressure discharge fluid flowed through the clearance and led to the increase of the average pressure and fluid force. When the leakage clearance is 1.0mm, the average pressure is far lower than that at the 0.5mm clearance, and the hydraulic efficiency is the highest.
HYDRAULICS, LOUISA COUNTY, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydraulic analysis for estimating flood stages for a flood insurance study. It...
EPA and the United Parcel Service (UPS) have developed a hydraulic hybrid delivery vehicle to explore and demonstrate the environmental benefits of the hydraulic hybrid for urban pick-up and delivery fleets.
Study on Characteristics of Hydraulic Servo System for Force Control of Hydraulic Robots
Kim, Hyo-gon; Han, Changsoo [Hanyang University, Seoul (Korea, Republic of); Lee, Jong-won [Korea University of Science and Technology, Seoul (Korea, Republic of); Park, Sangdeok [Korea Institute of Industrial Technology, Seoul (Korea, Republic of)
2015-02-15
Because a hydraulic actuator has high power and force densities, this allows the weight of the robot's limbs to be reduced. This allows for good dynamic characteristics and high energy efficiency. Thus, hydraulic actuators are used in some exoskeleton robots and quadrupedal robots that require high torque. Force control is useful for robot compliance with a user or environment. However, force control of a hydraulic robot is difficult because a hydraulic servo system is highly nonlinear from a control perspective. In this study, a nonlinear model was used to develop a simulation program for a hydraulic servo system consisting of a servo valve, transmission lines, and a cylinder. The problems and considerations with regard to the force control performance for a hydraulic servo system were investigated. A force control method using the nonlinear model was proposed, and its effect was evaluated with the simulation program.
A novel energy recovery system for parallel hybrid hydraulic excavator.
Li, Wei; Cao, Baoyu; Zhu, Zhencai; Chen, Guoan
2014-01-01
Hydraulic excavator energy saving is important to relieve source shortage and protect environment. This paper mainly discusses the energy saving for the hybrid hydraulic excavator. By analyzing the excess energy of three hydraulic cylinders in the conventional hydraulic excavator, a new boom potential energy recovery system is proposed. The mathematical models of the main components including boom cylinder, hydraulic motor, and hydraulic accumulator are built. The natural frequency of the proposed energy recovery system is calculated based on the mathematical models. Meanwhile, the simulation models of the proposed system and a conventional energy recovery system are built by AMESim software. The results show that the proposed system is more effective than the conventional energy saving system. At last, the main components of the proposed energy recovery system including accumulator and hydraulic motor are analyzed for improving the energy recovery efficiency. The measures to improve the energy recovery efficiency of the proposed system are presented.
Reducing-resistance mechanism of vibratory excavation of hydraulic excavator
ZHU Jian-xin; YANG Cheng-yun; HU Huo-yan; ZOU Xiang-fu
2008-01-01
Based on the working principle of vibratory excavation of hydraulic excavator, the expression of digging resistance changed with time under sine wave inspiritment was deduced; a comparison analysis was given after calculating the forces status of rock and soil under static load and vibratory load respectively by using MATLAB; and then RFPA-2D(rock failure process analysis code) was used to make comparison of simulation experiment on rock and soil failure process under static load and vibratory load. The results demonstrate that, compared with the normal excavation under the same situation, the digging resistance and the energy consumption can be reduced by respectively 30% and 60% at maximum, and that the working efficiency can be increased by 45% at maximum owing to vibratory excavation.
张付英; 李腾; 洪彬
2014-01-01
针对传统密封设计基于经验和技巧、没有理论和方法指导的问题，提出弹性往复密封的增效设计理论。在分析弹性液压往复密封的失效形式和增效机制的基础上，提出弹性往复密封增效设计的概念，确立使密封高效和无泄漏的增效准则。根据增效准则，提出弹性往复密封的增效设计技术体系。该理论提高了密封设计过程的规范化和可操作性，有效提高了密封设计的效率和质量。%Aimed at the problems that the seal design relies on empirical means without methods guiding,the efficiency-reinforcement design theories for elastomeric hydraulic reciprocating seals were proposed.Based on the exploration in the failure types and efficiency-reinforcement mechanism of elastomeric reciprocating seals,the concept of efficiency reinforce-ment design for elastomeric reciprocating seals was put forward,the efficiency-reinforcement rules were built which could realize the high reliability and efficiency of seals and zero leakage.According to the efficiency-reinforcement rules,the ef-fi ciency-reinforcement design technologies for elastomeric reciprocating seals were proposed.This theory improves the normal-ization and operability of the seal design,and improves the design quality and efficiency of elastomeric reciprocating seal.
Technology of load-sensitivity used in the hydraulic system of an all-hydraulic core rig
XIN De-zhong; CHEN Song-ling; WANG Qing-feng
2009-01-01
The existing hydraulic system always have problems of temperature rise, run-ning stability and anti-interference of the implementation components, reliability of hydrau-lic components, maintenance difficulties, and other issues. With high efficiency, energy saving, reliability, easy operating, stable running, anti-interference ability, and other ad-vantages, the load-sensitive hydraulic system is more suitable for coal mine all-hydraulic core rig. Therefore, for the technical development of the coal mine all-hydraulic core rig, the load-sensitive technology employed by the rig should be of great significance.
2016-01-01
The leaf venation architecture is an ideal, highly structured and efficient irrigation system in plant leaves. Leaf vein density (LVD) and vein thickness are the two major properties of this system. Leaf laminae carry out photosynthesis to harvest the maximum biological yield. It is still unknown whether the LVD and/or leaf vein thickness determines the plant hydraulic conductance (K plant) and leaf photosynthetic rate (A). To investigate this topic, the current study was conducted with two v...
李沁; 宋新山; 陆化杰; 严登华
2012-01-01
Series of simulated horizontal subsurface-flow constructed wetlands using different sized glass beads (4-9,8-12,11-17 mm) as wetland filter media were established to investigate the effect of heterogeneous porous media on the hydraulic efficiency of the wetland. Flow through the filter bed was visualized by injecting dyed fluid into the water-saturated model. The hydraulic parameters such as hydraulic retention time, effective volume fraction and hy draulic efficiency were detected using chloride tracer. The flow patterns were also analyzed. Results showed that the dyed fluid in different experiment apparatus presented different flow pattern. In the simulated constructed wetland filled with small grain size glass beads (4-9 mm) , the dyed fluid from top inlet to bottom outlet had the highest effec tive volume, means the constructed wetland had the highest space utilization ratio, effective volume ratio and dye flow distribution area, the dyed fluid was in arc shape around the corner, and the dead area was the smallest. When the di ameter of glass beads ranged 4-9 mm, the mean retention time of wetland and its distribution divergence was 0. 437 8 h and 0. 052 5, the effective volume ratio and hydraulic efficiency of wetland was 0. 495 7 and 0. 469 6 respectively. With increasing the diameter of glass beads, the mean retention time was shortened, the distribution divergence of mean retention time was increased and the effective volume ratio and hydraulic efficiency were decreased. Reasonable distribution of hydraulic retention time could increase the effective volume ratio of wetland, namely the wetland had larger effective volume for sewage migration, which was benefit for the sufficient connection of pollutants, substrate and microbes in substrate, so as to improve the removal efficient of pollutants.%对比以不同粒径(4～9、8～12、11～17 mm)非均质多孔介质(玻璃珠)作为基质的水平潜流人工湿地(以有机玻璃板材模拟)的水力效率
The effect of maximum open height on operating characteristics of polymer injected pump poppet valve
Zhang, S. C.; Chen, X. D.; Deng, H. Y.
2012-11-01
Reciprocating polymer injected pump is the key injection equipment of tertiary oil recovery, the poppet valve in it exists the problem of large vibration noise, low efficiency and short life when transportation high viscosity medium. So the CFD technique is adopted to simulate and analyze the inner flow fields of fluid end poppet valve. According to the practical structure of the poppet valve, a simplified 2D axis-symmetry geometry model of the flow field is established. Combined with pump speed, plunger stroke and plunger diameter, given the boundary condition of the inlet valve, then the numerical simulation of flow field under six different maximum open heights is done depending on software Fluent. The relationship between open height to valve gap flow velocity, hydraulic loss and lag angle is obtained. The results indicate that, with the increase of open height, the valve gap flow velocity decreases, inlet outlet pressure differential decreases and hydraulic loss decreases. But the lag angle is continuously increasing with the increase of maximum open height, the valve has a good work performance when the open height is 1, 1.5, 2, 2.5, 3mm, but when it reaches 3.5mm, the valve performance becomes poor. The study can offer certain reference to understand operating characteristics of poppet valve, help to reduce the hydraulic losses and raise volume efficiency of the pump.
Denisov, S. L.; Korolkov, A. I.
2017-07-01
A study of the phenomenon of diffraction of acoustic waves in application to the task of noise shielding by the method of maximum length sequences has been carried out. Rectangular plates and an aircraft model of integrated layout are used as the screens. In the study of noise shielding by aircraft model, the theorem of reciprocity is used. A comparison of experimental results with calculations performed in the framework of the geometrical theory of diffraction (GTD) is performed. On the basis of calculations, the identification of the contributions from different areas of the shielding surface in the full acoustic field is carried out. For the aircraft model, the shielding factor is calculated depending on the frequency.
Sauer, T. [ebm-papst Mulfingen GmbH und Co. KG, Mulfingen (Germany)
2006-03-15
Blowers are often powered by rotary-current asynchronous motors with short-circuit rotors, which are robust, simple and reliable. Today, specifications have become more demanding. For example, economic efficiency and low noise - combined with speed control which again should be as simple as possible - are now required. Asynchronous motors are hardly capable of meeting these requirements, so they are being replaced in many applications by electronically commuted permanent magnet motors, so-called EC drives. (orig.)
Morillon Galvez, David [Comision Nacional para el Ahorro de Energia, Mexico, D. F. (Mexico)
1999-07-01
An analysis of the elements and factors that the architecture of buildings must have to be sustainable, such as: a design adequate to the environment, saving and efficient use of alternate energies, and the auto-supply is presented. In addition a methodology for the natural air conditioning (bioclimatic architecture) of buildings, as well as ideas for the saving and efficient use of energy, with the objective of contributing to the adequate use of components of the building (walls, ceilings, floors etc.), is presented, that when interacting with the environment it takes advantage of it, without deterioration of the same, obtaining energy efficient designs. [Spanish] Se presenta un analisis de los elementos y factores que debe tener la arquitectura de edificios para ser sustentable, como; un diseno adecuado al ambiente, ahorro y uso eficiente de la energia, el uso de energias alternas y el autoabastecimiento. Ademas se propone una metodologia para la climatizacion natural (arquitectura bioclimatica) de edificios, asi como ideas para el ahorro y uso eficiente de energia, con el objetivo de aportar al uso adecuado de componentes del edificio (muros, techos, pisos etc.) que al interactuar con el ambiente tome ventaja de el, sin deterioro del mismo, logrando disenos energeticamente eficientes.
Thermal-hydraulic modeling and analysis of hydraulic system by pseudo-bond graph
胡均平; 李科军
2015-01-01
To increase the efficiency and reliability of the thermodynamics analysis of the hydraulic system, the method based on pseudo-bond graph is introduced. According to the working mechanism of hydraulic components, they can be separated into two categories: capacitive components and resistive components. Then, the thermal-hydraulic pseudo-bond graphs of capacitive C element and resistance R element were developed, based on the conservation of mass and energy. Subsequently, the connection rule for the pseudo-bond graph elements and the method to construct the complete thermal-hydraulic system model were proposed. On the basis of heat transfer analysis of a typical hydraulic circuit containing a piston pump, the lumped parameter mathematical model of the system was given. The good agreement between the simulation results and experimental data demonstrates the validity of the modeling method.
HYDRAULIC UNITS FOR DRIVING SYSTEMS OF RUNNING EQUIPMENT IN ROAD CONSTRUCTION MACHINERY
A. Ja. Kotlobai
2016-01-01
Full Text Available Operational efficiency of multi-functional road construction machines depends on number of working bodies which are simultaneously performing technological operations. Systems for propulsion pto to the running equipment drive and active working bodies of road construction machines are developing in the way of using three-axis hydraulic drives. When designing a hydraulic system for road construction machinery dividing of power flow from propulsion to the running equipment drive and active working bodies is considered as rather essential problem. Leading companies do not pay attention to the development of flow divider designs, preferring to produce more expensive multi-flow pumps. One of the ways to increase efficiency of multi-functional road construction machinery is an implementation of running equipment hydraulic driving system based on a mono-aggregate pump unit which consists of a pump and a volumetric divider of power fluid flow. A principle of volumetric division and summing-up of power fluid flows, technical realization and methodology for calculation of key parameters of discrete flow distributors has been developed on the basis of discrete hydraulics regulations. The paper presents results of mathematical modeling of hydraulic systems equipped with the discrete flow distributor. Analysis of a dual-motor hydraulic drive operation has shown the following results: a discrete flow distributor ensures independent load mode of the current consumer circuit operation from the load mode of the second consumer circuit within a wide range of loads; rational value of working fluid flow discretization parameter is the following value interval k = 4–6, maximum value of parameter efficiency is reached when an angular velocity of a distributor rotor coincides with the angular velocity of a pump shaft; discrete flow distributor provides a possibility to change parameters of hydraulic flow feeding in consumers’ pressure lines within a wide range
Thermally Actuated Hydraulic Pumps
Jones, Jack; Ross, Ronald; Chao, Yi
2008-01-01
Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research
Drawing a pictogram operator - hydraulic stowing assembly
Bukhgol' ts, V.P.; Dinershtein, V.A.
1984-11-01
Hydraulic stowing is widely used during the extraction of coal from seams prone to spontaneous ignition or from seams situated under preserved structures. Experience has shown that the presence of a considerable number of controlling and measuring devices on hydraulic stowing assemblies results in erratic operations. The authors, after examining the controls of the hydraulic stowing complexes, recommend that all functions which the operator might perform badly or not at all should be controlled automatically. The operator must, however, have access to manual controls which should be included in the system in order to achieve an effective and trouble free operation. The authors propose a pictogram to explain the relationship between the human operator and the hydraulic complex, based on structural diagrams. The system developed, which was tried out at the Koksovaya mine, increased the efficiency of the complex and reduced the work load of the operator. 3 references.
I.P. van Staveren (Irene)
2009-01-01
textabstractThe dominant economic theory, neoclassical economics, employs a single economic evaluative criterion: efficiency. Moreover, it assigns this criterion a very specific meaning. Other – heterodox – schools of thought in economics tend to use more open concepts of efficiency, related to comm
Research on hydraulic-powered roof supports test problems
SUN Hong-bo; JIANG Jin-qiu; MA Qiang
2011-01-01
The load-bearing characters of hydraulic-powered roof support with dual telescopic legs were analyzed. With a specific type hydraulic-powered roof support with dual telescopic legs for research object, the inside load test problems in factories was analyzed, and the correct test methods were given, which can enhance the test efficiency and make the factories away from the error design of hydraulic-powered roof supports and legs.
Costa, Rui J.; Wilkinson-Herbots, Hilde
2017-01-01
The isolation-with-migration (IM) model is commonly used to make inferences about gene flow during speciation, using polymorphism data. However, it has been reported that the parameter estimates obtained by fitting the IM model are very sensitive to the model’s assumptions—including the assumption of constant gene flow until the present. This article is concerned with the isolation-with-initial-migration (IIM) model, which drops precisely this assumption. In the IIM model, one ancestral population divides into two descendant subpopulations, between which there is an initial period of gene flow and a subsequent period of isolation. We derive a very fast method of fitting an extended version of the IIM model, which also allows for asymmetric gene flow and unequal population sizes. This is a maximum-likelihood method, applicable to data on the number of segregating sites between pairs of DNA sequences from a large number of independent loci. In addition to obtaining parameter estimates, our method can also be used, by means of likelihood-ratio tests, to distinguish between alternative models representing the following divergence scenarios: (a) divergence with potentially asymmetric gene flow until the present, (b) divergence with potentially asymmetric gene flow until some point in the past and in isolation since then, and (c) divergence in complete isolation. We illustrate the procedure on pairs of Drosophila sequences from ∼30,000 loci. The computing time needed to fit the most complex version of the model to this data set is only a couple of minutes. The R code to fit the IIM model can be found in the supplementary files of this article. PMID:28193727
Vibration of hydraulic machinery
Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong
2013-01-01
Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...
Handbook of hydraulic fluid technology
Totten, George E
2011-01-01
""The Handbook of Hydraulic Fluid Technology"" serves as the foremost resource for designing hydraulic systems and for selecting hydraulic fluids used in engineering applications. Featuring new illustrations, data tables, as well as practical examples, this second edition is updated with essential information on the latest hydraulic fluids and testing methods. The detailed text facilitates unparalleled understanding of the total hydraulic system, including important hardware, fluid properties, and hydraulic lubricants. Written by worldwide experts, the book also offers a rigorous overview of h
楚双霞; 刘林华
2011-01-01
There are five typical approximate formulae of maximum conversion efficiency, which are often used for the second law analysis of the utilization of terrestrial solar radiation. Based on Candau's definition of radiative exergy and solar spectral radiation databank developed by Gueymard, the maximum conversion efficiencies (exergy-to-energy ratio) of terrestrial solar radiation under different air mass and tilt angle were obtained and taken as benchmark solution. The accuracies of these five typical approximate formulae of maximum conversion efficiency were compared and analyzed under different atmospheric condition and tilt angle. The results show that, for maximum conversion efficiency of terrestrial solar radiation, the approximate formulae that proposed by Petela, Spanner, Parrot and Jeter overestimates, while that proposed by Badescu underestimates largely. Atmospheric condition heavily affects maximum conversion efficiency of terrestrial solar radiation. The influence of atmospheric condition should be taken into account on the exact computation of maximum conversion efficiency of terrestrial solar radiation for the second law analysis of solar energy conversion systems.%在对应用地表太阳辐射的系统进行热力学第二定律分析时,经常采用5个典型的太阳辐射最大转化效率计算公式.在Candau给出的辐射(火用)的定义和Gueymard公布的太阳光谱辐射数据的基础上,该文首先获得了不同大气条件和接收面下地表太阳辐射的最大转化效率(火用)和能间比值),并将其作为基准数据,比较和分析了不同大气条件和接收面下由5个典型公式计算得到的地表太阳辐射最大转化效率的精度.结果表明由Petela、Spanner、Parrot和Jeter提出的公式的计算结果高估了地表太阳辐射的最大转化效率,而由Badescu提出的公式计算得到的结果远远低估了地表太阳辐射的最大转化效率.大气条件对地表太阳辐射最大转化效率
Universal asymptotic umbrella for hydraulic fracture modeling
Linkov, Aleksandr M
2014-01-01
The paper presents universal asymptotic solution needed for efficient modeling of hydraulic fractures. We show that when neglecting the lag, there is universal asymptotic equation for the near-front opening. It appears that apart from the mechanical properties of fluid and rock, the asymptotic opening depends merely on the local speed of fracture propagation. This implies that, on one hand, the global problem is ill-posed, when trying to solve it as a boundary value problem under a fixed position of the front. On the other hand, when properly used, the universal asymptotics drastically facilitates solving hydraulic fracture problems (both analytically and numerically). We derive simple universal asymptotics and comment on their employment for efficient numerical simulation of hydraulic fractures, in particular, by well-established Level Set and Fast Marching Methods.
FEMA DFIRM Hydraulic Structures
Minnesota Department of Natural Resources — This layer and accompanying attribute table is required whenever hydraulic structures are shown in the flood profile. It is also required if levees are shown on the...
Conrad, Finn
2005-01-01
The paper presents research results using IT-Tools for CAD and dynamic modelling, simulation, analysis, and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. Matlab/Simulink and CATIA are used as IT-Tools. The contributions include results from on......-going research projects on fluid power and mechatronics based on tap water hydraulic servovalves and linear servo actuators and rotary vane actuators for motion control and power transmission. Development and design a novel water hydraulic rotary vane actuator for robot manipulators. Proposed mathematical...... modelling, control and simulation of a water hydraulic rotary vane actuator applied to power and control a two-links manipulator and evaluate performance. The results include engineering design and test of the proposed simulation models compared with IHA Tampere University’s presentation of research...
Constant-Pressure Hydraulic Pump
Galloway, C. W.
1982-01-01
Constant output pressure in gas-driven hydraulic pump would be assured in new design for gas-to-hydraulic power converter. With a force-multiplying ring attached to gas piston, expanding gas would apply constant force on hydraulic piston even though gas pressure drops. As a result, pressure of hydraulic fluid remains steady, and power output of the pump does not vary.
Vibration Isolation for Parallel Hydraulic Hybrid Vehicles
The M. Nguyen
2008-01-01
Full Text Available In recent decades, several types of hybrid vehicles have been developed in order to improve the fuel economy and to reduce the pollution. Hybrid electric vehicles (HEV have shown a significant improvement in fuel efficiency for small and medium-sized passenger vehicles and SUVs. HEV has several limitations when applied to heavy vehicles; one is that larger vehicles demand more power, which requires significantly larger battery capacities. As an alternative solution, hydraulic hybrid technology has been found effective for heavy duty vehicle because of its high power density. The mechanical batteries used in hydraulic hybrid vehicles (HHV can be charged and discharged remarkably faster than chemical batteries. This feature is essential for heavy vehicle hybridization. One of the main problems that should be solved for the successful commercialization of HHV is the excessive noise and vibration involving with the hydraulic systems. This study focuses on using magnetorheological (MR technology to reduce the noise and vibration transmissibility from the hydraulic system to the vehicle body. In order to study the noise and vibration of HHV, a hydraulic hybrid subsystem in parallel design is analyzed. This research shows that the MR elements play an important role in reducing the transmitted noise and vibration to the vehicle body. Additionally, locations and orientations of the isolation system also affect the efficiency of the noise and vibration mitigation. In simulations, a skyhook control algorithm is used to achieve the highest possible effectiveness of the MR isolation system.
Review of Hydraulic Fracturing for Preconditioning in Cave Mining
He, Q.; Suorineni, F. T.; Oh, J.
2016-12-01
Hydraulic fracturing has been used in cave mining for preconditioning the orebody following its successful application in the oil and gas industries. In this paper, the state of the art of hydraulic fracturing as a preconditioning method in cave mining is presented. Procedures are provided on how to implement prescribed hydraulic fracturing by which effective preconditioning can be realized in any in situ stress condition. Preconditioning is effective in cave mining when an additional fracture set is introduced into the rock mass. Previous studies on cave mining hydraulic fracturing focused on field applications, hydraulic fracture growth measurement and the interaction between hydraulic fractures and natural fractures. The review in this paper reveals that the orientation of the current cave mining hydraulic fractures is dictated by and is perpendicular to the minimum in situ stress orientation. In some geotechnical conditions, these orientation-uncontrollable hydraulic fractures have limited preconditioning efficiency because they do not necessarily result in reduced fragmentation sizes and a blocky orebody through the introduction of an additional fracture set. This implies that if the minimum in situ stress orientation is vertical and favors the creation of horizontal hydraulic fractures, in a rock mass that is already dominated by horizontal joints, no additional fracture set is added to that rock mass to increase its blockiness to enable it cave. Therefore, two approaches that have the potential to create orientation-controllable hydraulic fractures in cave mining with the potential to introduce additional fracture set as desired are proposed to fill this gap. These approaches take advantage of directional hydraulic fracturing and the stress shadow effect, which can re-orientate the hydraulic fracture propagation trajectory against its theoretical predicted direction. Proppants are suggested to be introduced into the cave mining industry to enhance the
Pedersen, Henrik Clemmensen
2004-01-01
in a project to develop rules and methods for designing and controlling mobile hydraulic systems in the most energy efficient way, when also considering the operational aspects of the system. The paper first describes the thoughts and ideas behind the project and then focus on an automated approach to design......Throughout the last three decades energy consumption has become one of the primary design aspects in hydraulic systems, especially for mobile hydraulic systems, as power and cooling capacity here is at limited disposal. Considering the energy usage, this is dependent on component efficiency......, but even more important is the system topology. However, there are no rules or guidelines for what system topology to choose for a given application, in order to obtain the most energy efficient system, nor for how the energy should be distributed in the system. This paper describes the approach taken...
Parameter Designing for Heave Compensation Hydraulic System Installed in Deepwater
Zhao Teng
2013-01-01
Full Text Available The function diagram of active heave compensation hydraulic system has been given, besides, the mathematics model for the principal hydraulic components of the compensation system has been built, and the input-output relation between components has been made clear. Aimed at compensating work capacity for the system, design and research on parameters as the bearing pressure, the initial state and the maximum flow of hydraulic cylinder, accumulator and other principal components have been made separately, and standardized design has been accomplished in accordance with relevant standards. Furthermore, calculus and verification for the capacity of the hydraulic system in different working stages have been made in order to calculate the pressure lose of the system and provide objective data for the hardware system design of the hydraulic components of the heave compensation system.
Deshimaru, Jun' ichi
1988-11-01
The gear, vane and piston pumps occupy a more then 90% share in the hydraulic pumps. Comparatively large pumps are mainly variable delivery piston pumps. The piston pumps are comparatively high in output density (output per unit weight), indicating the hydraulic pump in performance, and tend to become higher and higher in it. Though they are mainly 210 to 350kgf/cm/sup 2/ in rated pressure, some of them come to surpass 400kgf/cm/sup 3/ in it. While the progress in computation also requires the high speed operation, high accuracy and other severe conditions for the hydraulic units, which accordingly and increasingly intensify the requirement for hydraulic oil in abrasion resistibility, oxidation stability and response characteristics. While cavitation comes to easily occur, which considerably and disadvantageously influences hydraulic oil in life through degradation, noise level and respondingness. From now on, the development of high performance oil and study of mechanical structure are important. 19 references, 9 figures, 2 tables.
Trade-offs between xylem hydraulic properties, wood anatomy and yield in Populus.
Hajek, Peter; Leuschner, Christoph; Hertel, Dietrich; Delzon, Sylvain; Schuldt, Bernhard
2014-07-01
Trees face the dilemma that achieving high plant productivity is accompanied by a risk of drought-induced hydraulic failure due to a trade-off in the trees' vascular system between hydraulic efficiency and safety. By investigating the xylem anatomy of branches and coarse roots, and measuring branch axial hydraulic conductivity and vulnerability to cavitation in 4-year-old field-grown aspen plants of five demes (Populus tremula L. and Populus tremuloides Michx.) differing in growth rate, we tested the hypotheses that (i) demes differ in wood anatomical and hydraulic properties, (ii) hydraulic efficiency and safety are related to xylem anatomical traits, and (iii) aboveground productivity and hydraulic efficiency are negatively correlated to cavitation resistance. Significant deme differences existed in seven of the nine investigated branch-related anatomical and hydraulic traits but only in one of the four coarse-root-related anatomical traits; this likely is a consequence of high intra-plant variation in root morphology and the occurrence of a few 'high-conductivity roots'. Growth rate was positively related to branch hydraulic efficiency (xylem-specific conductivity) but not to cavitation resistance; this indicates that no marked trade-off exists between cavitation resistance and growth. Both branch hydraulic safety and hydraulic efficiency significantly depended on vessel size and were related to the genetic distance between the demes, while the xylem pressure causing 88% loss of hydraulic conductivity (P88 value) was more closely related to hydraulic efficiency than the commonly used P50 value. Deme-specific variation in the pit membrane structure may explain why vessel size was not directly linked to growth rate. We conclude that branch hydraulic efficiency is an important growth-influencing trait in aspen, while the assumed trade-off between productivity and hydraulic safety is weak.
A conceptual model of check dam hydraulics for gully control
C. Castillo
2013-09-01
Full Text Available There is little information in scientific literature regarding the modifications induced by check dam systems in flow regimes in restored gully reaches, despite it being a crucial issue for the design of conservation measures. Here, we develop a conceptual model to classify flow regimes in straight rectangular channels for initial and dam-filling conditions as well as a method of estimating efficiency in order to provide guidelines for optimal design. The model integrates several previous mathematical approaches for assessing the main processes involved (hydraulic jump HJ, impact flow, gradually varied flows. Its performance was compared with the simulations obtained from IBER, a bi-dimensional hydrodynamic model. The impact of check dam spacing (defined by the geometric factor of influence c on efficiency was explored. Eleven main classifications of flow regimes were identified depending on the element and level of influence. The model produced similar results when compared with IBER, but led to higher estimations of HJ and impact lengths. Total influence guaranteed maximum efficiency and HJ control defining the location of the optimal c. Geometric total influence (c = 1 was a valid criterion for the different stages of the structures in a wide range of situations provided that hydraulic roughness conditions remained high within the gully, e.g. through revegetation. Our total influence criterion involved shorter spacing than that habitually recommended in technical manuals for restoration, but was in line with those values found in spontaneous and stable step-pools systems, which might serve as a reference for man-made interventions.
Microbial effect on soil hydraulic properties
Furman, Alex; Rosenzweig, Ravid; Volk, Elazar; Rosenkranz, Hella; Iden, Sascha; Durner, Wolfgang
2014-05-01
Although largely ignored, the soil contains large amount of biofilms (attached microbes) that can affect many processes. While biochemical processes are studied, biophysical processes receive only little attention. Biofilms may occupy some of the pore space, and by that affect the soil hydraulic properties. This effect on unsaturated soils, however, was not intensively studied. In this research we directly measure the hydraulic properties, namely the soil's unsaturated hydraulic conductivity function and retention curve, for soils containing real biofilm. To do that we inoculate soil with biofilm-forming bacteria and incubate it with sufficient amounts of nutrient until biofilm is formed. The hydraulic properties of the incubated soil are then measured using several techniques, including multi-step outflow and evaporation method. The longer measurements (evaporation method) are conducted under refrigeration conditions to minimize microbial activity during the experiment. The results show a clear effect of the biofilm, where the biofilm-affected soil (sandy loam in our case) behaves like a much finer soil. This qualitatively makes sense as the biofilm generates an effective pore size distribution that is characterized by smaller pores. However, the effect is much more complex and needs to be studied carefully considering (for example) dual porosity models. We compare our preliminary results with other experiments, including flow-through column experiments and experiments with biofilm analogues. Clearly a better understanding of the way microbial activity alters the hydraulic properties may help designing more efficient bioremediation, irrigation, and other soil-related processes.
Cavitation in Hydraulic Machinery
Kjeldsen, M.
1996-11-01
The main purpose of this doctoral thesis on cavitation in hydraulic machinery is to change focus towards the coupling of non-stationary flow phenomena and cavitation. It is argued that, in addition to turbulence, superimposed sound pressure fluctuations can have a major impact on cavitation and lead to particularly severe erosion. For the design of hydraulic devices this finding may indicate how to further limit the cavitation problems. Chapter 1 reviews cavitation in general in the context of hydraulic machinery, emphasizing the initial cavitation event and the role of the water quality. Chapter 2 discusses the existence of pressure fluctuations for situations common in such machinery. Chapter 3 on cavitation dynamics presents an algorithm for calculating the nucleation of a cavity cluster. Chapter 4 describes the equipment used in this work. 53 refs., 55 figs.,10 tabs.
Parr, Andrew
2006-01-01
Nearly all industrial processes require objects to be moved, manipulated or subjected to some sort of force. This is frequently accomplished by means of electrical equipment (such as motors or solenoids), or via devices driven by air (pneumatics) or liquids (hydraulics).This book has been written by a process control engineer as a guide to the operation of hydraulic and pneumatic systems for all engineers and technicians who wish to have an insight into the components and operation of such a system.This second edition has been fully updated to include all recent developments su
Popeye Project: Hydraulic umbilical
Jordan, K.G.; Williams, V.T.
1996-12-31
For the Popeye Project, the longest super-duplex hydraulic umbilical in the world was installed in the Gulf of Mexico. This paper reports on its selection and project implementation. Material selection addresses corrosion in seawater, water-based hydraulic fluid, and methanol. Five alternatives were considered: (1) carbon-steel with traditional coating and anodes, (2) carbon-steel coated with thermally sprayed aluminum, (3) carbon-steel sheathed in aluminum, (4) super-duplex, and (5) titanium. The merits and risks associated with each alternative are discussed. The manufacture and installation of the selected umbilical are also reported.
Hydraulic Arm Modeling via Matlab SimHydraulics
Věchet, Stanislav; Krejsa, Jiří
2009-01-01
System modeling is a vital tool for cost reduction and design process speed up in most engineering fields. The paper is focused on modeling of hydraulic arm as a part of intelligent prosthesis project, in the form of 2DOF open kinematic chain. The arm model combines mechanical, hydraulic and electric subsystems and uses Matlab as modeling tool. SimMechanics Matlab extension is used for mechanical part modeling, SimHydraulics toolbox is used for modeling of hydraulic circuit used for actuating...
Maximum Autocorrelation Factorial Kriging
Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.
2000-01-01
This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from...
HYDRAULICS, TUSCARAWAS COUNTY, OHIO, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydraulic procedures for estimating flood discharges for a flood insurance...
Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik
1997-01-01
This paper describes a case study of identifying the physical model (or the grey box model) of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application...
Water Treatment Technology - Hydraulics.
Ross-Harrington, Melinda; Kincaid, G. David
One of twelve water treatment technology units, this student manual on hydraulics provides instructional materials for three competencies. (The twelve units are designed for a continuing education training course for public water supply operators.) The competencies focus on the following areas: head loss in pipes in series, function loss in…
Conrad, Finn
2005-01-01
The paper presents research results using IT-Tools for CAD and dynamic modelling, simulation, analysis, and design of water hydraulic actuators for motion control of machines, lifts, cranes and robots. Matlab/Simulink and CATIA are used as IT-Tools. The contributions include results from on-going...
COHESIVE ZONE FINITE ELEMENT-BASED MODELING OF HYDRAULIC FRACTURES
Zuorong Chen; A.P. Bunger; Xi Zhang; Robert G. Jeffrey
2009-01-01
Hydraulic fracturing is a powerful technology used to stimulate fluid production from reservoirs. The fully 3-D numerical simulation of the hydraulic fracturing process is of great importance to the efficient application of this technology, but is also a great challenge because of the strong nonlinear coupling between the viscous flow of fluid and fracture propagation. By taking advantage of a cohesive zone method to simulate the fracture process, a finite element model based on the existing pore pressure cohesive finite elements has been established to investigate the propagation of a penny-shaped hydraulic fracture in an infinite elastic medium. The effect of cohesive material parameters and fluid viscosity on the hydraulic fracture behaviour has been investigated. Excellent agreement between the finite element results and analytical solutions for the limiting case where the fracture process is dominated by rock fracture toughness demonstrates the ability of the cohesive zone finite element model in simulating the hydraulic fracture growth for this case.
Hydraulic analysis of cell-network treatment wetlands
Wang, Huaguo; Jawitz, James W.
2006-11-01
SummaryWhen individual cells of a multiple-cell treatment wetland are hydraulically connected, the wetland has a cell-network structure. The hydraulic performance of treatment wetlands is often characterized using tracer residence time distributions (RTDs) measured between the wetland inlet and outlet, such that the wetland is considered as a single hydraulic unit, regardless of the extent of networking between individual internal cells. This work extends the single hydraulic unit approach to enable the specification of moments and RTD parameters for individual cells, or clusters of cells, within the cell-network based on inert tracer tests with injection only at the network inlet. Hydraulic performance is quantified in terms of hydraulic efficiency and travel time dimensionless variance using both the method of moments and RTD modeling. Cell-network analysis was applied to a case study from the Orlando Easterly Wetland (OEW), demonstrating the improvement in hydraulic performance of individual wetland cells following wetland restoration activities. Furthermore, cell-network analysis indicated that the location of water quality sampling station locations within the cell network can significantly affect the accuracy of pollutant removal effectiveness estimation when the individual sample station RTD does not represent the hydraulic unit RTD. At the OEW, it was determined that historical nutrient removal effectiveness estimation may be underestimated for one area and overestimated for another, and recommendations were provided for sample station locations to minimize future performance estimation errors.
Hydraulic manipulator research at ORNL
Kress, R.L.; Jansen, J.F. [Oak Ridge National Lab., TN (United States); Love, L.J. [Oak Ridge Inst. for Science and Education, TN (United States)
1997-03-01
Recently, task requirements have dictated that manipulator payload capacity increase to accommodate greater payloads, greater manipulator length, and larger environmental interaction forces. General tasks such as waste storage tank cleanup and facility dismantlement and decommissioning require manipulator life capacities in the range of hundreds of pounds rather than tens of pounds. To meet the increased payload capacities demanded by present-day tasks, manipulator designers have turned once again to hydraulics as a means of actuation. In order to successfully design, build, and deploy a new hydraulic manipulator (or subsystem), sophisticated modeling, analysis, and control experiments are usually needed. Oak Ridge National Laboratory (ORNL) has a history of projects that incorporate hydraulics technology, including mobile robots, teleoperated manipulators, and full-scale construction equipment. In addition, to support the development and deployment of new hydraulic manipulators, ORNL has outfitted a significant experimental laboratory and has developed the software capability for research into hydraulic manipulators, hydraulic actuators, hydraulic systems, modeling of hydraulic systems, and hydraulic controls. The purpose of this article is to describe the past hydraulic manipulator developments and current hydraulic manipulator research capabilities at ORNL. Included are example experimental results from ORNL`s flexible/prismatic test stand.
Hydraulic Conductivity of Compacted Laterite Treated with Iron Ore Tailings
Umar Sa’eed Yusuf
2016-01-01
Full Text Available The objective of this study was to investigate the effect of iron ore tailings (IOT on hydraulic conductivity of compacted laterite. The IOT conforms to ASTM C 618-15 Type F designations. In the present study, soil was admixed with 0–20% IOT and compacted at moulding water content ranging from 10 to 25% using four types of compactive efforts. Hydraulic conductivities of the compacted soil-IOT mixtures were determined using deionized water and municipal solid waste leachate as the permeant fluids, respectively. Deionized water was the reference permeant fluid. Results of this study showed that hydraulic conductivity decreased with increase in IOT content as a result of improvement in mechanical properties of the soil. Permeation of the soil-IOT mixtures with leachate caused the hydraulic conductivity to drop to less than 1 × 10−9 m/s especially at higher compactive efforts. Also, bioclogging of the soil pores due to accumulation of biomass from bacteria and yeast present in the leachate tends to significantly reduce the hydraulic conductivity. From an economic point of view, it has been found from the results of this study that soil specimens treated with up to 20% IOT and compacted at the British Standard Light (BSL compactive effort met the maximum regulatory hydraulic conductivity of less than or equal to 1 × 10−9 m/s for hydraulic barrier system.
Partially decoupled modeling of hydraulic fracturing processes
Settari, A.; Puchyr, P.J.; Bachman, R.C. (Simtech Consulting Services, Calgary (CA))
1990-02-01
A new method of partial decoupling of the problem of modeling a hydraulic fracture in a reservoir is described. According to the authors this approach has significant advantages over previous methods with fully coupled or completely uncoupled models. Better accuracy can be achieved in modeling the fracture propagation, and the new system is very efficient and versatile. Virtually any reservoir model can be used for predicting postfracture productivity. Examples of single- and multiphase applications for modeling fractured wells are discussed.
Oscar Castro-Orgaz
2015-04-01
Full Text Available The transition from subcritical to supercritical flow when the inflow Froude number Fo is close to unity appears in the form of steady state waves called undular hydraulic jump. The characterization of the undular hydraulic jump is complex due to the existence of a non-hydrostatic pressure distribution that invalidates the gradually-varied flow theory, and supercritical shock waves. The objective of this work is to present a mathematical model for the undular hydraulic jump obtained from an approximate integration of the Reynolds equations for turbulent flow assuming that the Reynolds number R is high. Simple analytical solutions are presented to reveal the physics of the theory, and a numerical model is used to integrate the complete equations. The limit of application of the theory is discussed using a wave breaking condition for the inception of a surface roller. The validity of the mathematical predictions is critically assessed using physical data, thereby revealing aspects on which more research is needed
On the Dynamic Measurements of Hydraulic Characteristics
Hasmatuchi, Vlad; Bosioc, Alin; Münch-Alligné, Cécile
2016-11-01
The present work introduces the implementation and validation of a faster method to measure experimentally the efficiency characteristics of hydraulic turbomachines at a model scale on a test rig. The case study is represented by a laboratory prototype of an in-line axial microturbine for water supply networks. The 2.65 kW one-stage variable speed turbine, composed by one upstream 5-blade runner followed by one counter-rotating downstream 7-blade runner, has been installed on the HES-SO Valais/Wallis universal test rig dedicated to assess performances of small hydraulic machinery following the IEC standard recommendations. In addition to the existing acquisition/control system of the test rig used to measure the 3D hill-chart of a turbine by classical static point-by-point method, a second digitizer has been added to acquire synchronized dynamic signals of the employed sensors. The optimal acceleration/deceleration ramps of the electrical drives have been previously identified in order to cope with the purpose of a reduced measurement time while avoiding errors and hysteresis on the acquired hydraulic characteristics. Finally, the comparison between the turbine efficiency hill-charts obtained by dynamic and static point-by-point methods shows a very good agreement in terms of precision and repeatability. Moreover, the applied dynamic method reduces significantly (by a factor of up to ten) the time necessary to measure the efficiency characteristics on model testing.
赵斌; 权龙; 郝云晓
2016-01-01
电梯作为高层建筑运输人及货物的设备，自发明至今一直为人们的出行提供便捷；但诸多研究表明电梯能耗占高层建筑总能耗的20%左右，尤其是在能源供需矛盾日益突出的今天，电梯能耗已成为制约其发展和应用的主要问题。为降低电梯能耗，达到电梯节能运行的目的，结合曳引电梯的结构特点、运行特性及能耗特性，提出并设计一种新型的电-液混合驱动高能效曳引电梯节能系统。对传统电梯的运行特性进行分析，进而对提出的新型节能原理进行分析。建立曳引电梯能耗的仿真模型，并对传统电梯和节能电梯运行过程中的能耗进行仿真分析，仿真结果表明新型节能系统的节能效果明显。搭建电梯节能综合试验平台，通过在高层建筑进行能耗试验，验证仿真模型的准确性，试验结果表明新型节能系统的节能效率约为10%～14%。本文的研究成果不但是曳引电梯节能方面的发展方向之一，而且在其他垂直提升机械中也具有较好的应用前景。%Elevators are increasingly irreplaceable in the modernization of society, and since their invention, they have undergone several generations of replacement and technology upgrades, while providing convenience for people to move. Numerous studies show that the energy consumed by elevators accounts for about 20% of the total energy consumption of high-rise buildings. Especially in the energy supply and demand contradictions becoming increasingly prominent today, the energy consumption has become the main problem which restricts the elevators development and application. In order to reduce the elevator energy consumption and achieve the energy saving operational purpose, this study proposed and designed a new type of high-efficiency hybrid electric-hydraulic drive energy-saving traction elevator system based on the structural, operating, and energy
Determining the Conditions for the Hydraulic Impacts Emergence at Hydraulic Systems
Mazurenko A.S.
2017-08-01
Full Text Available This research aim is to develop a method for modeling the conditions for the critical hydrau-lic impacts emergence on thermal and nuclear power plants’ pipeline systems pressure pumps depart-ing from the general provisions of the heat and hydrodynamic instability theory. On the developed method basis, the conditions giving rise to the reliability-critical hydraulic impacts emergence on pumps for the thermal and nuclear power plants’ typical pipeline system have been determined. With the flow characteristic minimum allowable (critical sensitivity, the flow velocity fluctuations ampli-tude reaches critical values at which the pumps working elements’ failure occurs. The critical hydrau-lic impacts emergence corresponds to the transition of the vibrational heat-hydrodynamic instability into an aperiodic one. As research revealed, a highly promising approach as to the preventing the criti-cal hydraulic impacts related to the foreground use of pumps having the most sensitive consumption (at supply network performance (while other technical characteristics corresponding to that parame-ter. The research novelty refers to the suggested method elaborated by the authors’ team, which, in contrast to traditional approaches, is efficient in determining the pump hydraulic impact occurrence conditions when the vibrational heat-hydrodynamic instability transition to the aperiodic instability.
RESEARCH ON THE ENERGY ECONOMIZATION OF ELECTRO-HYDRAULIC HAMMER
无
2000-01-01
The research on the driving principle and economization of energy of electro-hydraulic hammer is discussed. By means of the Balance chart of energy, the method and formulas to calculate every level efficiency and the total efficiency of steam drived hammer are formed. With the aid of actual data of plants, the actual efficiency of steam drived hammer is got. The working principle and the driving system of electro-hydraulic hammer are introduced. The procedure of energy transfer of this hammer is analyzed. The utilization ratio of energy of this type of hammer is got. It is shown that the efficiency of electro-hydraulic hammer is 7 times as much as that of steam drived hammer.
Slide stability of hydraulic structures on subbed soil
Zhou Junliang
2013-01-01
The study on slide stability of hydraulic structures on subbed soil was made. Using the slide test results of dragged concreting base plates on subbed soil pits,the decreased value of bearing capacity on slide after re-bound and repression influence of subbed soil was determined,and the envelope of ultimate slide shear resistance was also quantitatively determined. Due to the lack of similar mechanisms of slide stability on subbed soil and base plate of hydraulic structures,different safety coefficients for the slide stability were adopted. It was suggested to use the maximum compressive stress σmax of eccentric load to predict structure displacement,slide and creepy slippage of subbed soil,to determine the sliding creepy contour and limit the maximum load on subbed soil. Two hydraulic structures that had been put into operation were reviewed by this method,and the results accorded with the real conditions.
The inverse maximum dynamic flow problem
BAGHERIAN; Mehri
2010-01-01
We consider the inverse maximum dynamic flow (IMDF) problem.IMDF problem can be described as: how to change the capacity vector of a dynamic network as little as possible so that a given feasible dynamic flow becomes a maximum dynamic flow.After discussing some characteristics of this problem,it is converted to a constrained minimum dynamic cut problem.Then an efficient algorithm which uses two maximum dynamic flow algorithms is proposed to solve the problem.
Characterisation of hydraulically-active fractures in a fractured ...
2015-01-07
Jan 7, 2015 ... maximum depth of the tunnel is 90–100 m from the peak of a mountain located above the .... g is the gravity acceleration l is the length of the test ..... process and is a hydraulically-active fracture conducting ground- water flow.
A 6-DOF vibration isolation system for hydraulic hybrid vehicles
Nguyen, The; Elahinia, Mohammad; Olson, Walter W.; Fontaine, Paul
2006-03-01
This paper presents the results of vibration isolation analysis for the pump/motor component of hydraulic hybrid vehicles (HHVs). The HHVs are designed to combine gasoline/diesel engine and hydraulic power in order to improve the fuel efficiency and reduce the pollution. Electric hybrid technology is being applied to passenger cars with small and medium engines to improve the fuel economy. However, for heavy duty vehicles such as large SUVs, trucks, and buses, which require more power, the hydraulic hybridization is a more efficient choice. In function, the hydraulic hybrid subsystem improves the fuel efficiency of the vehicle by recovering some of the energy that is otherwise wasted in friction brakes. Since the operation of the main component of HHVs involves with rotating parts and moving fluid, noise and vibration are an issue that affects both passengers (ride comfort) as well as surrounding people (drive-by noise). This study looks into the possibility of reducing the transmitted noise and vibration from the hydraulic subsystem to the vehicle's chassis by using magnetorheological (MR) fluid mounts. To this end, the hydraulic subsystem is modeled as a six degree of freedom (6-DOF) rigid body. A 6-DOF isolation system, consisting of five mounts connected to the pump/motor at five different locations, is modeled and simulated. The mounts are designed by combining regular elastomer components with MR fluids. In the simulation, the real loading and working conditions of the hydraulic subsystem are considered and the effects of both shock and vibration are analyzed. The transmissibility of the isolation system is monitored in a wide range of frequencies. The geometry of the isolation system is considered in order to sustain the weight of the hydraulic system without affecting the design of the chassis and the effectiveness of the vibration isolating ability. The simulation results shows reduction in the transmitted vibration force for different working cycles of
Time-dependent water permeation behavior of concrete under constant hydraulic pressure
Fang Yonghao; Wang Zhongli; Zhou Yue
2008-01-01
In the present work, a concrete permeability testing setup was designed to study the behavior of hydraulic concrete subjected to constant hydraulic pressure. The results show that when concrete is subjected to high enough constant hydraulic pressure, it will be permeated, and after it reaches its maximum permeation rate, the permeability coefficient will gradually decrease towards a stable value. A time-dependent model of permeability coefficient for concrete subjected to hydraulic pressure is proposed. It is indicated that the decrease of the permeability coefficient with permeation time conforms well to the negative-exponential decrease model.
Maximum Autocorrelation Factorial Kriging
Nielsen, Allan Aasbjerg; Conradsen, Knut; Pedersen, John L.; Steenfelt, Agnete
2000-01-01
This paper describes maximum autocorrelation factor (MAF) analysis, maximum autocorrelation factorial kriging, and its application to irregularly sampled stream sediment geochemical data from South Greenland. Kriged MAF images are compared with kriged images of varimax rotated factors from an ordinary non-spatial factor analysis, and they are interpreted in a geological context. It is demonstrated that MAF analysis contrary to ordinary non-spatial factor analysis gives an objective discrimina...
Huffman, Lester H.; Knoke, Gerald S.
1985-08-20
A method of hydraulically mining an underground pitched mineral vein comprising drilling a vertical borehole through the earth's lithosphere into the vein and drilling a slant borehole along the footwall of the vein to intersect the vertical borehole. Material is removed from the mineral vein by directing a high pressure water jet thereagainst. The resulting slurry of mineral fragments and water flows along the slant borehole into the lower end of the vertical borehole from where it is pumped upwardly through the vertical borehole to the surface.
Abderrahmane, Hamid; Kasimov, Aslan
2013-11-01
We report an experimental observation of a new symmetry breaking of circular hydraulic jump into a self-organized structure that consists of a spinning polygonal jump and logarithmic-spiral waves of fluid elevation downstream. The waves are strikingly similar to spiral density waves in galaxies. The fluid flow exhibits counterparts of salient morphological features of galactic flows, in particular the outflow from the center, jets, circum-nuclear rings, gas inflows toward the galactic center, and vortices. The hydrodynamic instability revealed here may have a counterpart that plays a role in the formation and sustainability of spiral arms in galaxies.
张玖霞; 方杰
2011-01-01
In this paper,Meihekou scale intensive arable land to achieve good results as the starting point,the transfer of land from the government guidance to promote,develop policies to create conditions for the scale,speed up the transfer of rural labor to expand the scale of operation in space in the analysis of Meihekou scale intensive arable land on the remarkable results.Meanwhile,for the land transfer process Meihekou exist in many non-standard issues,from land to carry out intensive,in order to achieve maximum efficiency of land use perspective,on how to do large-scale land operation Meihekou proposed measures.%本文以梅河口市做好耕地集约规模经营取得的成效为切入点,从政府引导推动土地流转,制定优惠扶持政策为规模经营创造条件,加快农村劳动力转移为规模经营拓展空间等方面分析了梅河口市在耕地集约规模经营上取得的显著成效。同时,针对梅河口市在土地流转过程中存在的问题,从实现土地使用效益最大化的视角,对梅河口市如何做好土地规模经营提出了相关的对策。
Maximum magnitude earthquakes induced by fluid injection
McGarr, Arthur F.
2014-01-01
Analysis of numerous case histories of earthquake sequences induced by fluid injection at depth reveals that the maximum magnitude appears to be limited according to the total volume of fluid injected. Similarly, the maximum seismic moment seems to have an upper bound proportional to the total volume of injected fluid. Activities involving fluid injection include (1) hydraulic fracturing of shale formations or coal seams to extract gas and oil, (2) disposal of wastewater from these gas and oil activities by injection into deep aquifers, and (3) the development of enhanced geothermal systems by injecting water into hot, low-permeability rock. Of these three operations, wastewater disposal is observed to be associated with the largest earthquakes, with maximum magnitudes sometimes exceeding 5. To estimate the maximum earthquake that could be induced by a given fluid injection project, the rock mass is assumed to be fully saturated, brittle, to respond to injection with a sequence of earthquakes localized to the region weakened by the pore pressure increase of the injection operation and to have a Gutenberg-Richter magnitude distribution with a b value of 1. If these assumptions correctly describe the circumstances of the largest earthquake, then the maximum seismic moment is limited to the volume of injected liquid times the modulus of rigidity. Observations from the available case histories of earthquakes induced by fluid injection are consistent with this bound on seismic moment. In view of the uncertainties in this analysis, however, this should not be regarded as an absolute physical limit.
Maximum magnitude earthquakes induced by fluid injection
McGarr, A.
2014-02-01
Analysis of numerous case histories of earthquake sequences induced by fluid injection at depth reveals that the maximum magnitude appears to be limited according to the total volume of fluid injected. Similarly, the maximum seismic moment seems to have an upper bound proportional to the total volume of injected fluid. Activities involving fluid injection include (1) hydraulic fracturing of shale formations or coal seams to extract gas and oil, (2) disposal of wastewater from these gas and oil activities by injection into deep aquifers, and (3) the development of enhanced geothermal systems by injecting water into hot, low-permeability rock. Of these three operations, wastewater disposal is observed to be associated with the largest earthquakes, with maximum magnitudes sometimes exceeding 5. To estimate the maximum earthquake that could be induced by a given fluid injection project, the rock mass is assumed to be fully saturated, brittle, to respond to injection with a sequence of earthquakes localized to the region weakened by the pore pressure increase of the injection operation and to have a Gutenberg-Richter magnitude distribution with a b value of 1. If these assumptions correctly describe the circumstances of the largest earthquake, then the maximum seismic moment is limited to the volume of injected liquid times the modulus of rigidity. Observations from the available case histories of earthquakes induced by fluid injection are consistent with this bound on seismic moment. In view of the uncertainties in this analysis, however, this should not be regarded as an absolute physical limit.
46 CFR 28.880 - Hydraulic equipment.
2010-10-01
... hydraulic equipment and the adjacent work area. Protection shall be afforded to the operator of hydraulic... 46 Shipping 1 2010-10-01 2010-10-01 false Hydraulic equipment. 28.880 Section 28.880 Shipping... INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.880 Hydraulic equipment. (a) Each hydraulic system must...
Konev, V.; Polovnikov, E.; Krut, O.; Merdanov, Sh; Zakirzakov, G.
2017-07-01
It’s determined that the main part of trailbuilders operated in the North is the technology equipped by the hydraulic actuator. Further development of the northern territories will demand using of various means and ways machinery thermal preparation, and also the machinery of the northern fulfillment. On this basis problems in equipment operation are defined. One of the main is efficiency supplying of a hydraulic actuator. On the basis of the operating conditions’ analysis of trailbuilder hydraulic actuator operation it is determined, that under low negative temperatures the means of thermal preparation are necessary. The existing systems warm up only a hydraulic tank or warming up of the hydro equipment before the machinery operation is carried out under loading with intensive wears. Thus, with the purpose to raise the efficiency of thermal hydraulic actuator, operated far from stationary bases autonomous, energy saving, not expensive in creation and operation systems are necessary. In accordance with the analysis of means and ways of the thermal preparation of the hydraulic actuator and the thermal balance calculations of the (internal) combustion engine the system of the hydraulic actuator heating is offered and is being investigated. It contains a local hydraulic actuator warming up and the system of internal combustion engine heat utilization. Within research operation conditions of the local hydraulic actuator heating are viewed and determined, taking into account constructive changes to the local hydraulic actuator heating. Mathematical modelling of the heat technical process in the modernized hydraulic actuator is considered. As a result temperature changes of the heat-transfer and the hydraulic cylinder in time are determined. To check the theoretical researches and to define dependences on hydraulic actuator warming up, the experimental installation is made. It contains the measuring equipment, a small tank with the heat exchanger of the burnt gases
Chaudhry, M Hanif
2014-01-01
This book covers hydraulic transients in a comprehensive and systematic manner from introduction to advanced level and presents various methods of analysis for computer solution. The field of application of the book is very broad and diverse and covers areas such as hydroelectric projects, pumped storage schemes, water-supply systems, cooling-water systems, oil pipelines and industrial piping systems. Strong emphasis is given to practical applications, including several case studies, problems of applied nature, and design criteria. This will help design engineers and introduce students to real-life projects. This book also: · Presents modern methods of analysis suitable for computer analysis, such as the method of characteristics, explicit and implicit finite-difference methods and matrix methods · Includes case studies of actual projects · Provides extensive and complete treatment of governed hydraulic turbines · Presents design charts, desi...
Variation of hydraulic gradient in nonlinear finite strain consolidation
谢新宇; 黄杰卿; 王文军; 李金柱
2014-01-01
In the research field of ground water, hydraulic gradient is studied for decades. In the consolidation field, hydraulic gradient is yet to be investigated as an important hydraulic variable. So, the variation of hydraulic gradient in nonlinear finite strain consolidation was focused on in this work. Based on lab tests, the nonlinear compressibility and nonlinear permeability of Ningbo soft clay were obtained. Then, a strongly nonlinear governing equation was derived and it was solved with the finite element method. Afterwards, the numerical analysis was performed and it was verified with the existing experiment for Hong Kong marine clay. It can be found that the variation of hydraulic gradient is closely related to the magnitude of external load and the depth in soils. It is interesting that the absolute value of hydraulic gradient (AVHG) increases rapidly first and then decreases gradually after reaching the maximum at different depths of soils. Furthermore, the changing curves of AVHG can be roughly divided into five phases. This five-phase model can be employed to study the migration of pore water during consolidation.
Ai, Shao-shui; Li, Yang-yang; Chen, Jia-cun; Chen, Wei-yue
2015-11-01
Root xylem anatomical structure and hydraulic traits of three typical shrubs, i.e., Salix psammophila, Caragana korshinskii and Hippophae rhamnoides, within two soil layers (0-20 cm and 30-50 cm) were compared. The results showed that S. psammophila had a higher leaf water potential than C. korshinskii and H. rhamnoides, the average maximum and minimum lumen diameter (d(max) and d(min), respectively), the average lumen area of vessels (Alum) and the ratio of lumen area of all vessels to xylem area (Aves/Axyl) in S. psammophila roots were also significantly higher than those in C. korshinskii and H. rhamnoides, and the root vessel density (VD) in S. psammophila was the same as that in H. rhamnoides but significantly higher than that in C. korshinskii. Root hydraulic conductivity in S. psammophila was 5 times of C. korshinskii and 2.8 times of H. hamnoides. The vulnerability index in S. psammophila roots was similar to that in C. korshinskii but higher than that in H. hamnoides. S. psammophila belonged to a water-spending species, whereas both C. korshinskii and H. rhamnoides were water-saving species, and C. korshinskii was more drought-resistant than H. rhamnoides. There was no difference of d(max), d(min) and Alum between roots in two soil layers, but roots within in the 30-50 cm soil layer had larger VD and Aves/Axyl. The root specific hydraulic conductivity within the 30-50 cm soil layer was significantly higher than within the surface soil layer, whereas the vulnerability index within the 30-50 cm soil layer was smaller, indicating roots in deep soil layers had higher hydraulic transport efficiency and lower hydraulic vulnerability.
Anti-rebound Cushion Device for Hydraulic Breaker
Zhao Hongqiang
2005-01-01
This paper analyzes the phenomenon of rebound impact and its negative influence on the present hydraulic breaker. To get over its shortcomings, a new anti-rebound cushion device has been designed to prevent the phenomenon of rebound impact. A hydraulic cushion is used to absorb the rebound impact energy, which can be released for the next stroke of the hydraulic breaker. Thus, there is little loss of energy, and the efficiency of the impact system can be increased by 5 %. The absorption effect of the hydraulic anti-rebound cushion increases the service life of breaker components by up to twice as long as in the current breaker. A dynamic model and a motion equation of the anti-rebound cushion device are presented, and the optimum frequency and damping ratio are obtained, providing optimum design parameters for the anti-rebound cushion device.
Automated Hydraulic System Design and Power Management in Mobile Applications
Pedersen, Henrik Clemmensen
a presentation of the used graph theory representation that is developed to represent a hydraulic open-circuit system and which is based on a numerical formulation that uniquely describe the system in terms of five set of design variables that describe respectively the topology, the components and the operating...... are found on most medium and high-end mobile hydraulic machinery. Despite the energy saving potentials that these systems posses, compared to the other open-circuit hydraulic system topologies, LS-system may still be subject to very low system efficiencies if not designed correctly. This is typically...... machines if operated in the intended and optimal work area, but due to an inappropriate system layout. Most of the power lost in open circuit hydraulic system systems is in this regard in the transmission part, i.e. hoses and fittings, and the valves used to control the system. A large part of the design...
Hydraulic rams; a comparative investigation
Tacke, J.H.P.M.
1988-01-01
A mathematical model describing the essential features of hydraulic ram operation is developed in order to clarify the possibilities and limitations of the ram relative to its site and its adjustments. The model distinguishes three different periods in the pumping cycle of the hydraulic ram: acceler
Hydraulics. FOS: Fundamentals of Service.
John Deere Co., Moline, IL.
This manual on hydraulics is one of a series of power mechanics texts and visual aids for training in the servicing of agricultural and industrial machinery. Focus is on oil hydraulics. Materials provide basic information and illustrations for use by vocational students and teachers as well as shop servicemen and laymen. The twelve chapters focus…
Study of the Process of Hydraulic Mixing in Anaerobic Digester of Biogas Plant
Karaeva Julia V.
2015-03-01
Full Text Available Two systems of hydraulic mixing in a vertical cylindrical anaerobic digester: standard and modernised are discussed in the paper. Numerical investigations that were carried out are focused on a study of hydrodynamic processes in an aerobic digester using two various systems of hydraulic mixing as well as on analysis of the efficiency of methane fermentation process accomplished under different geometric parameters of an anaerobic digester and systems of hydraulic mixing.
Zhang, Zhenzhen; Zhao, Ping; McCarthy, Heather R.; Ouyang, Lei; Niu, Junfeng; Zhu, Liwei; Ni, Guangyan; Huang, Yuqing
2016-01-01
A clear understanding of hydraulic regulation in cultivated plants is crucial for addressing challenges to forest water cycling due to climate changes in low subtropical China. Experiments were conducted to determine the hydrologic balance of a Eucalyptus urophylla plantation in response to periodic drought. Trees displayed lower stomatal conductance (GS) and leaf water potentials (ΨL) during the dry periods. A decrease of 22.4% was found for the maximum reference GS (GS at D = 1 kPa; GSref-max). Accordingly, specific hydraulic conductivity (ks) decreased by 45.3 – 65.6% from the wet to the dry season, depending on the tree size. Fairly stable leaf stomatal conductance (gs) with decreasing ΨL (ΨL < -1.6 MPa) contributed to the high water-use efficiency (WUE) of this Eucalyptus species. Additionally, the lower stomatal sensitivity (-m = 0.53) in the dry season might also be responsible for the high WUE, since we found an anisohydric behavior that was associated with photosynthetically active radiation (Q0). Larger trees were found to use water more efficiently than small trees, due to the higher sensitivity of ks to decreasing ΨL. This was also verified by the decreasing leaf carbon isotope discrimination (Δ13C) with increasing tree diameter. However, further studies are needed to determine the universality of these results for other Eucalyptus species in this region. PMID:27725821
Hydraulic Stability of Accropode Armour
Jensen, T.; Burcharth, H. F.; Frigaard, Peter
, and to assess the influence of core permeability on the hydraulic stability of Accropodes. Two structures were examined, one with a relatively permeable core and one with a relatively impermeable core. In November/December 1995, Ph.D.-student Marten Christensen carried out the model tests on the structure...... with permeable core (crushed granite with a gradation of 5-8 mm). The outcome of this study is described in "Hydraulic Stability of Single-Layer Dolos and Accropode Armour Layers" by Christensen & Burcharth (1995). In January/February 1996, Research Assistant Thomas Jensen carried out a similar study......The present report describes the hydraulic model tests of Accropode armour layers carried out at the Hydraulics Laboratory at Aalborg University from November 1995 through March 1996. The objective of the model tests was to investigate the hydraulic stability of Accropode armour layers...
Hydraulic Stability of Accropode Armour
Jensen, T.; Burcharth, H. F.; Frigaard, Peter
, and to assess the influence of core permeability on the hydraulic stability of Accropodes. Two structures were examined, one with a relatively permeable core and one with a relatively impermeable core. In November/December 1995, Ph.D.-student Marten Christensen carried out the model tests on the structure...... with permeable core (crushed granite with a gradation of 5-8 mm). The outcome of this study is described in "Hydraulic Stability of Single-Layer Dolos and Accropode Armour Layers" by Christensen & Burcharth (1995). In January/February 1996, Research Assistant Thomas Jensen carried out a similar study......The present report describes the hydraulic model tests of Accropode armour layers carried out at the Hydraulics Laboratory at Aalborg University from November 1995 through March 1996. The objective of the model tests was to investigate the hydraulic stability of Accropode armour layers...
Maximum likely scale estimation
Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo
2005-01-01
A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and/or ...
Stubkier, Søren; Pedersen, Henrik C.; Mørkholt, M.
As wind turbines increase in size, combined with increased lifetime demands, new methods for load reduction needs to be examined. One method is to make the yaw system of the turbine soft/flexible and hereby dampen the loads to the system, which is the focus of the current paper. By utilizing...... the HAWC2 aeroelastic code and an extended model of the NREL 5MW turbine combined with a simplified linear model of the turbine, the parameters of the soft yaw system are optimized to reduce loading in critical components. Results shows that a significant reduction in fatigue and extreme loads to the yaw...... system and rotor shaft when utilizing the soft yaw drive concept compared to the original stiff yaw system. The physical demands of the hydraulic yaw system are furthermore examined for a life time of 20 years. Based on the extrapolated loads, the duty cycles show that it is possible to construct...
Electro Hydraulic Hitch Control
Hansen, M. R.; Andersen, T. O.; Nielsen, B.
2003-01-01
system for agricultural applications and driving for transportation. During tranport phases, the lack of suspension causes the vehicle to bounce and pitch, and makes it difficalt to control. Many systems have been proposed to cope with the oscillatory behavior, and different solutions exist. Common......This paper present and discusses R&D results on electro hydraulic hitch control for off-road vehicle, in particular active damping of oscillation occuring on tractors. The research deals with analysis and control of the oscillations occuring on tractors which are design without any susspection...... for most of the systems are that they operate on the hydrailc actuators generally providing the motive forces for moving the implement and/or attachment, typically a plough. The basic idea and physical working principle are to use the implement, moveable relative to the vehicle, as a damper mass. The paper...
Maximum information photoelectron metrology
Hockett, P; Wollenhaupt, M; Baumert, T
2015-01-01
Photoelectron interferograms, manifested in photoelectron angular distributions (PADs), are a high-information, coherent observable. In order to obtain the maximum information from angle-resolved photoionization experiments it is desirable to record the full, 3D, photoelectron momentum distribution. Here we apply tomographic reconstruction techniques to obtain such 3D distributions from multiphoton ionization of potassium atoms, and fully analyse the energy and angular content of the 3D data. The PADs obtained as a function of energy indicate good agreement with previous 2D data and detailed analysis [Hockett et. al., Phys. Rev. Lett. 112, 223001 (2014)] over the main spectral features, but also indicate unexpected symmetry-breaking in certain regions of momentum space, thus revealing additional continuum interferences which cannot otherwise be observed. These observations reflect the presence of additional ionization pathways and, most generally, illustrate the power of maximum information measurements of th...
Hydraulic Actuators with Autonomous Hydraulic Supply for the Mainline Aircrafts
I. S. Shumilov
2014-01-01
Full Text Available Applied in the aircraft control systems, hydraulic servo actuators with autonomous hydraulic supply, so-called, hydraulic actuators of integrated configuration, i.e. combination of a source of hydraulic power and its load in the single unit, are aimed at increasing control system reliability both owing to elimination of the pipelines connecting the actuator to the hydraulic supply source, and owing to avoidance of influence of other loads failure on the actuator operability. Their purpose is also to raise control system survivability by eliminating the long pipeline communications and their replacing for the electro-conductive power supply system, thus reducing the vulnerability of systems. The main reason for a delayed application of the hydraulic actuators in the cutting-edge aircrafts was that such aircrafts require hydraulic actuators of considerably higher power with considerable heat releases, which caused an unacceptable overheat of the hydraulic actuators. Positive and negative sides of the hydraulic actuators, their alternative options of increased reliability and survivability, local hydraulic systems as an advanced alternative to independent hydraulic actuators are considered.Now to use hydraulic actuators in mainline aircrafts is inexpedient since there are the unfairly large number of the problems reducing, first and last, safety of flights, with no essential weight and operational advantages. Still works to create competitive hydraulic actuators ought to be continued.Application of local hydraulic systems (LHS will allow us to reduce length of pressure head and drain pipelines and mass of pipelines, as well as to raise their general fail-safety and survivability. Application of the LHS principle will allow us to use a majority of steering drive advantages. It is necessary to allocate especially the following:- ease of meeting requirements for the non-local spread of the engine weight;- essentially reducing length and weight of
Concept Design of Movable Beam of Hydraulic Press
Li Yancong
2017-01-01
Full Text Available The hydraulic press movable beam is one of the key components of the hydraulic press; its design quality impacts the accuracy of the workpiece that the press suppressed. In this paper, first, with maximum deflection and material strength as constraints, mechanical model of the movable beam is established; next, the concept design model of the moveable beam structure is established; the relationship among the force of the side cylinder, the thickness of the inclined plate, outer plate is established also. Taking movable beam of the 100MN type THP10-10000 isothermal forging hydraulic press as an example, the conceptual design result is given. This concept design method mentoned in the paper has general meaning and can apply to other similar product design.
Hydraulic conductivity of organomodified soil
Wallace, R.B.; Grant, J.M.; Voice, T.C.; Rakhshandehroo, G.; Xu, S.; Boyd, S.A. [Michigan State Univ., East Lansing, MI (United States)
1995-11-01
The effects of organomodification on soil hydraulic conductivity were investigated. Hydraulic conductivity and porosity of treated and untreated samples of a sandy loam were measured as a function of effective stress. Batch treatment with hexadecyltrimethyl ammonium (HDTMA) and dry packing produced organomodified samples that were 79% less conducive than untreated samples prior to loading. Treated samples lost less hydraulic conductivity as a result of loading than untreated samples so that treated samples had higher conductivity at high loads. Observed differences in conductivity are explained in terms of the role of the treated and untreated clay in controlling initial effective pore size and its change during consolidation.
A New Type of Hydraulic Muscle
Nitai Drimer
2016-01-01
Full Text Available This paper presents the invention and development of a new fundamental type of hydraulic actuator, aimed at delivering better actuation efficiency. This actuator is a flexible tube, composed of two different materials, which deflects while applying inner pressure. This concept is simple to produce, and allows adaptation of the deflected shape by the design parameters (radius, wall thickness, geometry, etc.. Among other applications, it is mostly suitable for the activation of fins of nature-like marine robots. Theoretical formulation, production of prototypes and actuation experiments are presented, as well as material hysteresis research and an application example.
Experimental Characterization and Modelling of Energy Efficient Fluid Supply Systems
Bjorklund, Karina M; Vacca, Andrea; Opperwall, Timothy J
2015-01-01
In applications such as in agriculture, construction, and aerospace applications, high pressure hydraulics is the preferred technology to transmit mechanical power. As a consequence, the energy efficiency of the hydraulic system used to perform the mechanical actuations is of primary concern to reduce the energy consumptions in the abovementioned applications. In an hydraulic system, the primary component determining the energy efficiency is the hydraulic pump. This work focuses on the study ...
A quantitative analysis of hydraulic interaction processes in stream-aquifer systems.
Wang, Wenke; Dai, Zhenxue; Zhao, Yaqian; Li, Junting; Duan, Lei; Wang, Zhoufeng; Zhu, Lin
2016-01-28
The hydraulic relationship between the stream and aquifer can be altered from hydraulic connection to disconnection when the pumping rate exceeds the maximum seepage flux of the streambed. This study proposes to quantitatively analyze the physical processes of stream-aquifer systems from connection to disconnection. A free water table equation is adopted to clarify under what conditions a stream starts to separate hydraulically from an aquifer. Both the theoretical analysis and laboratory tests have demonstrated that the hydraulic connectedness of the stream-aquifer system can reach a critical disconnection state when the horizontal hydraulic gradient at the free water surface is equal to zero and the vertical is equal to 1. A boundary-value problem for movement of the critical point of disconnection is established for an analytical solution of the inverted water table movement beneath the stream. The result indicates that the maximum distance or thickness of the inverted water table is equal to the water depth in the stream, and at a steady state of disconnection, the maximum hydraulic gradient at the streambed center is 2. This study helps us to understand the hydraulic phenomena of water flow near streams and accurately assess surface water and groundwater resources.
Maximum Likelihood Associative Memories
Gripon, Vincent; Rabbat, Michael
2013-01-01
Associative memories are structures that store data in such a way that it can later be retrieved given only a part of its content -- a sort-of error/erasure-resilience property. They are used in applications ranging from caches and memory management in CPUs to database engines. In this work we study associative memories built on the maximum likelihood principle. We derive minimum residual error rates when the data stored comes from a uniform binary source. Second, we determine the minimum amo...
Maximum likely scale estimation
Loog, Marco; Pedersen, Kim Steenstrup; Markussen, Bo
2005-01-01
A maximum likelihood local scale estimation principle is presented. An actual implementation of the estimation principle uses second order moments of multiple measurements at a fixed location in the image. These measurements consist of Gaussian derivatives possibly taken at several scales and....../or having different derivative orders. Although the principle is applicable to a wide variety of image models, the main focus here is on the Brownian model and its use for scale selection in natural images. Furthermore, in the examples provided, the simplifying assumption is made that the behavior...... of the measurements is completely characterized by all moments up to second order....
From the Kinetic Energy Recovery System to the Thermo-Hydraulic Hybrid Motor Vehicle
Cristescu, Corneliu; Drumea, Petrin; Guta, Dragos; Dumitrescu, Catalin
2011-12-01
The paper presents some theoretical and experimental results obtained by the Hydraulics and Pneumatics Research Institute INOE 2000-IHP with its partners, regarding the creating of one hydraulic system able to recovering the kinetic energy of the motor vehicles, in the braking phases, and use this recovered energy in the starting and accelerating phases. Also, in the article is presented a testing stand, which was especially designed for testing the hydraulic system for recovery the kinetic energy. Through mounting of the kinetic energy recovering hydraulic system, on one motor vehicle, this vehicle became a thermo-hydraulic hybrid vehicle. Therefore, the dynamic behavior was analyzed for the whole hybrid motor vehicle, which includes the energy recovery system. The theoretical and experimental results demonstrate the possible performances of the hybrid vehicle and that the kinetic energy recovery hydraulic systems are good means to increase energy efficiency of the road motor vehicles and to decrease of the fuel consumption.
Test investigation on hydraulic losses in the discharge passage of an axial-flow pump
QIU Baoyun; CAO Haihong; JIANG Wei; GAO Zhaohui; WANG Fei
2007-01-01
In a discharge passage with a guide blade dis- charge circulation and secondary flow because of bend pipe, the flow in a 1-channel discharge passage of an axial flow pump is a complicated spiral flow. For a 2-channel passage, the discharge in the left channel is bigger than that in the fight, and the passage hydraulic losses are abnormal. In this study, the section current energy of the passage is accurately mea- sured and determined with a 5-hole probe. The hydraulic loss characteristics are determined and analyzed. The methods deducing the hydraulic losses are investigated. The results indicate that the passage hydraulic losses are not proportional to the flow discharge. Compared with a circular pipe, the hydraulic losses of a divergent discharge passage are smaller and the pump assembly efficiency is 10%-30% higher. As for the 1-channel passage, the axial-flow pump outlet circulation is usually too big; the passage hydraulic losses are also big, but a small circulation can slightly reduce hydraulic losses. As for the 2-channel passage, discharges in the two channels are not equal and the hydraulic losses increase. The outlet guide blade with a small discharge circulation or without circulation could reduce discharge passage hydraulic losses and increase pump assembly efficiency by 6%-11%.
HYDRAULICS, ATHENS COUNTY, OHIO, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydrologic procedures for estimating flood discharges for a flood insurance...
HYDRAULICS, JACKSON COUNTY, KENTUCKY, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydrologic procedures for estimating flood discharges for a flood insurance...
HYDRAULICS, MADISON COUNTY, ALABAMA, USA
Federal Emergency Management Agency, Department of Homeland Security — This Hydraulic data was reviewed and approved by FEMA during the initial MT-2 processing. Recent developments in digital terrain and geospatial database management...
HYDRAULICS, HAMPDEN COUNTY, MA, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data in this submittal include spatial datasets and model outputs necessary for computation of the 1-percent flooding extent. The minimum requirement for...
Hydraulic wind energy conversion system
1981-07-01
The purpose of this research was to design, build and test a hydraulic wind energy system. This design used a three bladed turbine, which drove a hydraulic pump. The energy is transmitted from the pump through a long hose and into a hydraulic motor, where the energy is used. This wind system was built and tested during the winter of 1980-1981. The power train included a five meter, three bladed wind turbine, a 9.8:1 ratio gearbox, a 1.44 cubic inch displacement pump with a small supercharge gear pump attached. The hydraulic fluid was pumped through a 70', 3/4'' I-D-high pressure flexhose, then through a volume control valve and into a 1.44 cubic inch displacement motor. The fluid was returned through a 70', 1'' I-D-flexhose.
14 CFR 29.1435 - Hydraulic systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hydraulic systems. 29.1435 Section 29.1435... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Miscellaneous Equipment § 29.1435 Hydraulic systems. (a) Design. Each hydraulic system must be designed as follows: (1) Each element of the hydraulic system...
14 CFR 23.1435 - Hydraulic systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hydraulic systems. 23.1435 Section 23.1435... § 23.1435 Hydraulic systems. (a) Design. Each hydraulic system must be designed as follows: (1) Each hydraulic system and its elements must withstand, without yielding, the structural loads expected...
Advanced Performance Hydraulic Wind Energy
Jones, Jack A.; Bruce, Allan; Lam, Adrienne S.
2013-01-01
The Jet Propulsion Laboratory, California Institute of Technology, has developed a novel advanced hydraulic wind energy design, which has up to 23% performance improvement over conventional wind turbine and conventional hydraulic wind energy systems with 5 m/sec winds. It also has significant cost advantages with levelized costs equal to coal (after carbon tax rebate). The design is equally applicable to tidal energy systems and has passed preliminary laboratory proof-of-performance tests, as funded by the Department of Energy.
Improving hydraulic excavator performance through in line hydraulic oil contamination monitoring
Ng, Felix; Harding, Jennifer A.; Glass, Jacqueline
2017-01-01
It is common for original equipment manufacturers (OEMs) of high value products to provide maintenance or service packages to customers to ensure their products are maintained at peak efficiency throughout their life. To quickly and efficiently plan for maintenance requirements, OEMs require accurate information about the use and wear of their products. In recent decades, the aerospace industry in particular has become expert in using real time data for the purpose of product monitoring and maintenance scheduling. Significant quantities of real time usage data from product monitoring are commonly generated and transmitted back to the OEMs, where diagnostic and prognostic analysis will be carried out. More recently, other industries such as construction and automotive, are also starting to develop capabilities in these areas and condition based maintenance (CBM) is increasing in popularity as a means of satisfying customers' demands. CBM requires constant monitoring of real time product data by the OEMs, however the biggest challenge for these industries, in particular construction, is the lack of accurate and real time understanding of how their products are being used possibly because of the complex supply chains which exist in construction projects. This research focuses on current dynamic data acquisition techniques for mobile hydraulic systems, in this case the use of a mobile inline particle contamination sensor; the aim was to assess suitability to achieve both diagnostic and prognostic requirements of Condition Based Maintenance. It concludes that hydraulic oil contamination analysis, namely detection of metallic particulates, offers a reliable way to measure real time wear of hydraulic components.
Roemer, Daniel Beck; Bech, Michael Møller; Johansen, Per
2015-01-01
Fast-switching seat valves suitable for digital hydraulic pumps and motors utilize direct electromagnetic actuators, which must exhibit superior transient performance to allow efficient operation of the fluid power pump/motor. A moving coil actuator resulting in a minimum valve switching time.......5 bar at 600 L/min flow rate, enabling efficient operation of digital hydraulic pumps and motors....
Impact of ductility on hydraulic fracturing in shales
MacMinn, Chris; Auton, Lucy
2016-04-01
Hydraulic fracturing is a method for extracting natural gas and oil from low-permeability rocks such as shale via the high-pressure injection of fluid into the bulk of the rock. The goal is to initiate and propagate fractures that will provide hydraulic access deeper into the reservoir, enabling gas or oil to be collected from a larger region of the rock. Fracture is the tensile failure of a brittle material upon reaching a threshold tensile stress, but some shales have a high clay content and may yield plastically before fracturing. Plastic deformation is the shear failure of a ductile material, during which stress relaxes through irreversible rearrangements of the particles of the material. Here, we investigate the impact of the ductility of shales on hydraulic fracturing. We first consider a simple, axisymmetric model for radially outward fluid injection from a wellbore into a ductile porous rock. We use this model to show that plastic deformation greatly reduces the maximum tensile stress, and that this maximum stress does not always occur at the wellbore. We then complement these results with laboratory experiments in an analogue system, and with numerical simulations based on the discrete element method (DEM), both of which suggest that ductile failure can indeed dramatically change the resulting deformation pattern. These results imply that hydraulic fracturing may fail in ductile rocks, or that the required injection rate for fracking may be much larger than the rate predicted from models that assume purely elastic mechanical behavior.
F. TopsÃƒÂ¸e
2001-09-01
Full Text Available Abstract: In its modern formulation, the Maximum Entropy Principle was promoted by E.T. Jaynes, starting in the mid-fifties. The principle dictates that one should look for a distribution, consistent with available information, which maximizes the entropy. However, this principle focuses only on distributions and it appears advantageous to bring information theoretical thinking more prominently into play by also focusing on the "observer" and on coding. This view was brought forward by the second named author in the late seventies and is the view we will follow-up on here. It leads to the consideration of a certain game, the Code Length Game and, via standard game theoretical thinking, to a principle of Game Theoretical Equilibrium. This principle is more basic than the Maximum Entropy Principle in the sense that the search for one type of optimal strategies in the Code Length Game translates directly into the search for distributions with maximum entropy. In the present paper we offer a self-contained and comprehensive treatment of fundamentals of both principles mentioned, based on a study of the Code Length Game. Though new concepts and results are presented, the reading should be instructional and accessible to a rather wide audience, at least if certain mathematical details are left aside at a rst reading. The most frequently studied instance of entropy maximization pertains to the Mean Energy Model which involves a moment constraint related to a given function, here taken to represent "energy". This type of application is very well known from the literature with hundreds of applications pertaining to several different elds and will also here serve as important illustration of the theory. But our approach reaches further, especially regarding the study of continuity properties of the entropy function, and this leads to new results which allow a discussion of models with so-called entropy loss. These results have tempted us to speculate over
Regularized maximum correntropy machine
Wang, Jim Jing-Yan
2015-02-12
In this paper we investigate the usage of regularized correntropy framework for learning of classifiers from noisy labels. The class label predictors learned by minimizing transitional loss functions are sensitive to the noisy and outlying labels of training samples, because the transitional loss functions are equally applied to all the samples. To solve this problem, we propose to learn the class label predictors by maximizing the correntropy between the predicted labels and the true labels of the training samples, under the regularized Maximum Correntropy Criteria (MCC) framework. Moreover, we regularize the predictor parameter to control the complexity of the predictor. The learning problem is formulated by an objective function considering the parameter regularization and MCC simultaneously. By optimizing the objective function alternately, we develop a novel predictor learning algorithm. The experiments on two challenging pattern classification tasks show that it significantly outperforms the machines with transitional loss functions.
Boundary condition effects on maximum groundwater withdrawal in coastal aquifers.
Lu, Chunhui; Chen, Yiming; Luo, Jian
2012-01-01
Prevention of sea water intrusion in coastal aquifers subject to groundwater withdrawal requires optimization of well pumping rates to maximize the water supply while avoiding sea water intrusion. Boundary conditions and the aquifer domain size have significant influences on simulating flow and concentration fields and estimating maximum pumping rates. In this study, an analytical solution is derived based on the potential-flow theory for evaluating maximum groundwater pumping rates in a domain with a constant hydraulic head landward boundary. An empirical correction factor, which was introduced by Pool and Carrera (2011) to account for mixing in the case with a constant recharge rate boundary condition, is found also applicable for the case with a constant hydraulic head boundary condition, and therefore greatly improves the usefulness of the sharp-interface analytical solution. Comparing with the solution for a constant recharge rate boundary, we find that a constant hydraulic head boundary often yields larger estimations of the maximum pumping rate and when the domain size is five times greater than the distance between the well and the coastline, the effect of setting different landward boundary conditions becomes insignificant with a relative difference between two solutions less than 2.5%. These findings can serve as a preliminary guidance for conducting numerical simulations and designing tank-scale laboratory experiments for studying groundwater withdrawal problems in coastal aquifers with minimized boundary condition effects.
Design and Optimization of Fast Switching Valves for Large Scale Digital Hydraulic Motors
Roemer, Daniel Beck
of seat valves suitable for large scale digital hydraulic motors and detailed analysis methods for the pressure chambers of such machines. In addition, modeling methods of seat valves within this field have been developed, and a design method utilizing these models including optimization of subdomains has......The present thesis is on the design, analysis and optimization of fast switching valves for digital hydraulic motors with high power ratings. The need for such high power motors origins in the potential use of hydrostatic transmissions in wind turbine drive trains, as digital hydraulic machines...... have been shown to improve the overall efficiency and efficient operation range compared to traditional hydraulic machines. Digital hydraulic motors uses electronically controlled independent seat valves connected to the pressure chambers, which must be fast acting and exhibit low pressure losses...
Smart magnetic markers use in hydraulic fracturing.
Zawadzki, Jarosław; Bogacki, Jan
2016-11-01
One of the main challenges and unknowns during shale gas exploration is to assess the range and efficiency of hydraulic fracturing. It is also essential to assess the distribution of proppant, which keeps the fracture pathways open. Solving these problems may considerably increase the efficiency of the shale gas extraction. Because of that, the idea of smart magnetic marker, which can be detected when added to fracturing fluid, has been considered for a long time. This study provides overview of the possibilities of magnetic marker application for shale gas extraction. The imaging methods using electromagnetic markers, are considered or developed in two directions. The first possibility is the markers' electromagnetic activity throughout the whole volume of the fracturing fluid. Thus, it can be assumed that the whole fracturing fluid is the marker. Among these type of hydraulic fracturing solutions, ferrofluid could be considered. The second possibility is marker, which is just one of many components of the fracturing fluid. In this case feedstock magnetic materials, ferrites and nanomaterials could be considered. Magnetic properties of magnetite could be too low and ferrofluids' or nanomaterials' price is unacceptably high. Because of that, ferrites, especially ZnMn ferrites seems to be the best material for magnetic marker. Because of the numerous applications in electronics, it is cheap and easily available, although the price is higher, then that of magnetite. The disadvantage of using ferrite, could be too small mechanical strength. It creates an essential need for combining magnetic marker with proppant into magnetic-ceramic composite.
Drainage hydraulics of permeable friction courses
Charbeneau, Randall J.; Barrett, Michael E.
2008-04-01
This paper describes solutions to the hydraulic equations that govern flow in permeable friction courses (PFC). PFC is a layer of porous asphalt approximately 50 mm thick that is placed as an overlay on top of an existing conventional concrete or asphalt road surface to help control splash and hydroplaning, reduce noise, and enhance quality of storm water runoff. The primary objective of this manuscript is to present an analytical system of equations that can be used in design and analysis of PFC systems. The primary assumptions used in this analysis are that the flow can be modeled as one-dimensional, steady state Darcy-type flow and that slopes are sufficiently small so that the Dupuit-Forchheimer assumptions apply. Solutions are derived for cases where storm water drainage is confined to the PFC bed and for conditions where the PFC drainage capacity is exceeded and ponded sheet flow occurs across the pavement surface. The mathematical solutions provide the drainage characteristics (depth and residence time) as a function of rainfall intensity, PFC hydraulic conductivity, pavement slope, and maximum drainage path length.
Hydraulic fracture model comparison study: Complete results
Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States); Abou-Sayed, I.S. [Mobil Exploration and Production Services (United States); Moschovidis, Z. [Amoco Production Co. (US); Parker, C. [CONOCO (US)
1993-02-01
Large quantities of natural gas exist in low permeability reservoirs throughout the US. Characteristics of these reservoirs, however, make production difficult and often economic and stimulation is required. Because of the diversity of application, hydraulic fracture design models must be able to account for widely varying rock properties, reservoir properties, in situ stresses, fracturing fluids, and proppant loads. As a result, fracture simulation has emerged as a highly complex endeavor that must be able to describe many different physical processes. The objective of this study was to develop a comparative study of hydraulic-fracture simulators in order to provide stimulation engineers with the necessary information to make rational decisions on the type of models most suited for their needs. This report compares the fracture modeling results of twelve different simulators, some of them run in different modes for eight separate design cases. Comparisons of length, width, height, net pressure, maximum width at the wellbore, average width at the wellbore, and average width in the fracture have been made, both for the final geometry and as a function of time. For the models in this study, differences in fracture length, height and width are often greater than a factor of two. In addition, several comparisons of the same model with different options show a large variability in model output depending upon the options chosen. Two comparisons were made of the same model run by different companies; in both cases the agreement was good. 41 refs., 54 figs., 83 tabs.
Equalized near maximum likelihood detector
2012-01-01
This paper presents new detector that is used to mitigate intersymbol interference introduced by bandlimited channels. This detector is named equalized near maximum likelihood detector which combines nonlinear equalizer and near maximum likelihood detector. Simulation results show that the performance of equalized near maximum likelihood detector is better than the performance of nonlinear equalizer but worse than near maximum likelihood detector.
Cheeseman, Peter; Stutz, John
2005-01-01
A long standing mystery in using Maximum Entropy (MaxEnt) is how to deal with constraints whose values are uncertain. This situation arises when constraint values are estimated from data, because of finite sample sizes. One approach to this problem, advocated by E.T. Jaynes [1], is to ignore this uncertainty, and treat the empirically observed values as exact. We refer to this as the classic MaxEnt approach. Classic MaxEnt gives point probabilities (subject to the given constraints), rather than probability densities. We develop an alternative approach that assumes that the uncertain constraint values are represented by a probability density {e.g: a Gaussian), and this uncertainty yields a MaxEnt posterior probability density. That is, the classic MaxEnt point probabilities are regarded as a multidimensional function of the given constraint values, and uncertainty on these values is transmitted through the MaxEnt function to give uncertainty over the MaXEnt probabilities. We illustrate this approach by explicitly calculating the generalized MaxEnt density for a simple but common case, then show how this can be extended numerically to the general case. This paper expands the generalized MaxEnt concept introduced in a previous paper [3].
FAN Liwei; Hai Reti; WANG Wenxing; LU Zexiang; YANG Zhiming
2008-01-01
A subsurface flow wetland (SSFW) was simulated using a commercial computational fluid dynamic (CFD) code. The constructed media was simulated using porous media and the liquid resident time distribution (RTD) in the SSFW was obtained using the particle trajectory model. The effect of wetland configuration and operating conditions on the hydraulic performance of the SSFW were investigated. The results indicated that the hydraulic performance of the SSFW was predominantly affected by the wetland configuration. The hydraulic efficiency of the SSFW with an inlet at the middle edge of the upper media was 0.584 and the best among the SSFWs with an inlet at the top, the middle, and the bottom edge of the upper media. The constructed media affected the hydraulic performance by the ratio (K) of the upper and lower media resistance. The selection of appropriate media resistance in the protection layer can improve the hydraulic efficiency. When the viscous resistance coefficient of the media in the protection layer changed from 2.315×105 to 1.200×108, the hydraulic efficiency of the SSFW increased from 0.301 to 0.751. However, the effect of operating conditions on the hydraulic efficiency of the SSFW was slight.
Sugarcane Tandem Mills Operation at Two Hydraulic Pressure Levels
Jorge Michel Corrales-Suárez
2015-01-01
Full Text Available Among the areas with more energy consumption in a sugar factory is the tandem of mills. The applied hydraulic pressure on the superior mace is one of the variables that have influence on this energy consumption. Hydraulic pressures were decreased in a value that did not affect the extraction process efficiency to determine the possibilities of decreasing this energy consumption. The research was carried out in two sugar cane tandems of six mills. The pressures were only varied in the extraction mills in humid according to a statistical design of experiments in random blocks. The results were analyzed by means of the analysis of variance of double classification. The independent variables were the hydraulic pressures in the intermediate mills while the dependent variables were the % pol and % humidity of the final bagasse. The hydraulic pressures of the intermediate mills were reduced 3.45 MPa in the Tandem 1 and 2.07 MPa in the Tandem 2. It was demonstrated that under the conditions of the experiment, the employment of working hydraulic pressures smaller than the usually established ones for each tandem did not affect the extraction process of the sugar cane sucrose significantly, but decreased 11.75% the power demand on tandem 1 and 8.17% on tandem 2.
Changes in Root Hydraulic Conductivity During Wheat Evolution
Chang-Xing ZHAO; Xi-Ping DENG; Lun SHAN; Ernst STEUDLE; Sui-Qi ZHANG; Qing YE
2005-01-01
A better understanding of the mechanisms of water uptake by plant roots should be vital for improving drought resistance and water use efficiency (WUE). In the present study, we have demonstrated correlations between root system hydraulic conductivity and root characteristics during evolution using six wheat evolution genotypes (solution culture) with different ploidy chromosome sets (Triticum boeoticum Bioss., T. monococcum L.: 2n = 2x = 14; T. dicoccides Koern., T. dicoccon (Schrank) Schuebl.: 2n = 4x = 28;T. vulgare Vill., T. aestivum L. cv. Xiaoyan No. 6: 2n = 6x = 42). The experimental results showed that significant correlations were found between root system hydraulic conductivity and root characteristics of the materials with the increase in ploidy chromosomes (2x→6x) during wheat evolution. Hydraulic conductivity of the wheat root system at the whole-plant level was increased with chromosome ploidy during evolution, which was positively correlated with hydraulic conductivity of single roots, whole plant biomass,root average diameter, and root growth (length, area), whereas the root/shoot ratio had an inverse correlation with the hydraulic conductivity of root system with increasing chromosome ploidy during wheat evolution. Therefore, it is concluded that that the water uptake ability of wheat roots was strengthened from wild to modern cultivated species during evolution, which will provide scientific evidence for genetic breeding to improve the WUE of wheat by genetic engineering.
Kałuża, Tomasz; Radecki-Pawlik, Artur; Plesiński, Karol; Walczak, Natalia; Szoszkiewicz, Krzysztof; Radecki-Pawlik, Bartosz
2016-04-01
In the present time integrated water management is directly connected with management and direct works in river channels themselves which are taking into account morphological processes in rivers and improve flow conditions. Our work focused on the hydraulic and hydrodynamic consequences upon the introduction of the concept of the improvement of the hydromorphological conditions of the Flinta River in a given reach following river channel management concept. Based on a comprehensive study of the hydromorphological state of the river, four sections were selected where restoration measures can efficiently improve river habitat conditions in the river. For each section a set of technical and biological measures were proposed and implemented in practice. One of the proposed solutions was to construct plant basket hydraulic structures (PBHS) within the river channel, which are essentially plant barriers working as sediment traps, changing river channel morphology and are in line with concepts of Water Framework Directive. These relatively small structures work as crested weirs and unquestionably change the channel morphology. Along our work we show the results of three-year long (2013-2015) systematic measurements that provided information on the morphological consequences of introducing such structures into a river channel. Our main conclusions are as follows: 1. Plant basket hydraulic structures cause changes in hydrodynamic conditions and result in sediment accumulation and the formation of river backwaters upstream and downstream the obstacle; 2. The introduced plant basket hydraulic structures cause plant debris accumulation which influences the hydrodynamic flow conditions; 3. The installation of plant basket hydraulic structures on the river bed changes flow pattern as well as flow hydrodynamic conditions causing river braiding process; 4. The erosion rate below the plant basket hydraulic structures is due to the hydraulic work conditions of the PBHS and its
Low-power microfluidic electro-hydraulic pump (EHP).
Lui, Clarissa; Stelick, Scott; Cady, Nathaniel; Batt, Carl
2010-01-07
Low-power electrolysis-based microfluidic pumps utilizing the principle of hydraulics, integrated with microfluidic channels in polydimethylsiloxane (PDMS) substrates, are presented. The electro-hydraulic pumps (EHPs), consisting of electrolytic, hydraulic and fluidic chambers, were investigated using two types of electrodes: stainless steel for larger volumes and annealed gold electrodes for smaller-scale devices. Using a hydraulic fluid chamber and a thin flexible PDMS membrane, this novel prototype successfully separates the reagent fluid from the electrolytic fluid, which is particularly important for biological and chemical applications. The hydraulic advantage of the EHP device arises from the precise control of flow rate by changing the electrolytic pressure generated, independent of the volume of the reagent chamber, mimicking the function of a hydraulic press. Since the reservoirs are pre-filled with reagents and sealed prior to testing, external fluid coupling is minimized. The stainless steel electrode EHPs were manufactured with varying chamber volume ratios (1 : 1 to 1 : 3) as a proof-of-concept, and exhibited flow rates of 1.25 to 30 microl/min with electrolysis-based actuation at 2.5 to 10 V(DC). The miniaturized gold electrode EHPs were manufactured with 3 mm diameters and 1 : 1 chamber volume ratios, and produced flow rates of 1.24 to 7.00 microl/min at 2.5 to 10 V(AC), with a higher maximum sustained pressure of 343 KPa, suggesting greater device robustness using methods compatible with microfabrication. The proposed technology is low-cost, low-power and disposable, with a high level of reproducibility, allowing for ease of fabrication and integration into existing microfluidic lab-on-a-chip and analysis systems.
Effects of hydraulic pressure on the performance of single chamber air-cathode microbial fuel cells.
Cheng, Shaoan; Liu, Weifeng; Guo, Jian; Sun, Dan; Pan, Bin; Ye, Yaoli; Ding, Weijun; Huang, Haobin; Li, Fujian
2014-06-15
Scaling up of microbial fuel cells (MFCs) without losing power density requires a thorough understanding of the effect of hydraulic pressure on MFC performance. In this work, the performance of an activated carbon air-cathode MFC was evaluated under different hydraulic pressures. The MFC under 100 mmH2O hydraulic pressure produced a maximum power density of 1260 ± 24 mW m(-2), while the power density decreased by 24.4% and 44.7% as the hydraulic pressure increased to 500 mmH2O and 2000 mmH2O, respectively. Notably, the performance of both the anode and the cathode had decreased under high hydraulic pressures. Electrochemical impedance spectroscopy tests of the cathode indicated that both charge transfer resistance and diffusion transfer resistance increased with the increase in hydraulic pressure. Denaturing gradient gel electrophoresis of PCR-amplified partial 16S rRNA genes demonstrated that the similarity among anodic biofilm communities under different hydraulic pressures was ≥ 90%, and the communities of all MFCs were dominated by Geobacter sp. These results suggested that the reduction in power output of the single chamber air-cathode MFC under high hydraulic pressures can be attributed to water flooding of the cathode and suppression the metabolism of anodic exoelectrogenic bacteria.
Complex Fluids and Hydraulic Fracturing.
Barbati, Alexander C; Desroches, Jean; Robisson, Agathe; McKinley, Gareth H
2016-06-07
Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process.
Hydraulic properties of ladle slags
J. Vlček
2016-07-01
Full Text Available The article presents results of examining of hydraulic properties of ladle slags formed during production of steel. The studied ladle slags were subjected to different cooling mode from the molten state. Based on the ability of the slag react with the water was assessed their hydraulic activity. The hydraulic properties are caused by the presence of minerals dicalcium silicate, tricalcium aluminate, mayenite, brownmillerite and dicalcium ferite. The emergence of required hydrating phases in the ladle slags is conditioned by a sufficient CaO content and their cooling rate. The contact the slag with water during processing and their ageing has a negative effect. The experiment has shown that the phase transformation of the mineral dicalcium silicate which occurs during cooling of the ladle slags cause their volume instability.
Hao, Guang-You; Wang, Ai-Ying; Liu, Zhi-Hui; Franco, Augusto C; Goldstein, Guillermo; Cao, Kun-Fang
2011-06-01
Hemiepiphytic Ficus species (Hs) possess traits of more conservative water use compared with non-hemiepiphytic Ficus species (NHs) even during their terrestrial growth phase, which may result in significant differences in photosynthetic light use between these two growth forms. Stem hydraulic conductivity, leaf gas exchange and chlorophyll fluorescence were compared in adult trees of five Hs and five NHs grown in a common garden. Hs had significantly lower stem hydraulic conductivity, lower stomatal conductance and higher water use efficiency than NHs. Photorespiration played an important role in avoiding photoinhibition at high irradiance in both Hs and NHs. Under saturating irradiance levels, Hs tended to dissipate a higher proportion of excessive light energy through thermal processes than NHs, while NHs dissipated a larger proportion of electron flow than Hs through the alternative electron sinks. No significant difference in maximum net CO2 assimilation rate was found between Hs and NHs. Stem xylem hydraulic conductivity was positively correlated with maximum electron transport rate and negatively correlated with the quantum yield of non-photochemical quenching across the 10 studied Ficus species. These findings indicate that a canopy growth habit during early life stages in Hs of Ficus resulted in substantial adaptive differences from congeneric NHs not only in water relations but also in photosynthetic light use and carbon economy. The evolution of epiphytic growth habit, even for only part of their life cycle, involved profound changes in a suite of inter-correlated ecophysiological traits that persist to a large extent even during the later terrestrial growth phase.
Hydraulic resistance of biofilms
Dreszer, C.
2013-02-01
Biofilms may interfere with membrane performance in at least three ways: (i) increase of the transmembrane pressure drop, (ii) increase of feed channel (feed-concentrate) pressure drop, and (iii) increase of transmembrane passage. Given the relevance of biofouling, it is surprising how few data exist about the hydraulic resistance of biofilms that may affect the transmembrane pressure drop and membrane passage. In this study, biofilms were generated in a lab scale cross flow microfiltration system at two fluxes (20 and 100Lm-2h-1) and constant cross flow (0.1ms-1). As a nutrient source, acetate was added (1.0mgL-1 acetate C) besides a control without nutrient supply. A microfiltration (MF) membrane was chosen because the MF membrane resistance is very low compared to the expected biofilm resistance and, thus, biofilm resistance can be determined accurately. Transmembrane pressure drop was monitored. As biofilm parameters, thickness, total cell number, TOC, and extracellular polymeric substances (EPS) were determined, it was demonstrated that no internal membrane fouling occurred and that the fouling layer actually consisted of a grown biofilm and was not a filter cake of accumulated bacterial cells. At 20Lm-2h-1 flux with a nutrient dosage of 1mgL-1 acetate C, the resistance after 4 days reached a value of 6×1012m-1. At 100Lm-2h-1 flux under the same conditions, the resistance was 5×1013m-1. No correlation of biofilm resistance to biofilm thickness was found; Biofilms with similar thickness could have different resistance depending on the applied flux. The cell number in biofilms was between 4×107 and 5×108 cellscm-2. At this number, bacterial cells make up less than a half percent of the overall biofilm volume and therefore did not hamper the water flow through the biofilm significantly. A flux of 100Lm-2h-1 with nutrient supply caused higher cell numbers, more biomass, and higher biofilm resistance than a flux of 20Lm-2h-1. However, the biofilm thickness
Controls of Hydraulic Wind Turbine
Zhang Yin
2016-01-01
Full Text Available In this paper a hydraulic wind turbine generator system was proposed based on analysis the current wind turbines technologies. The construction and principles were introduced. The mathematical model was verified using MATLAB and AMsim. A displacement closed loop of swash plate of motor and a speed closed loop of generator were setup, a PID control is introduced to maintain a constant speed and fixed frequency at wind turbine generator. Simulation and experiment demonstrated that the system can connect grid to generate electric and enhance reliability. The control system demonstrates a high performance speed regulation and effectiveness. The results are great significant to design a new type hydraulic wind turbine system.
Integrating hydraulic equivalent sections into a hydraulic geometry study
Jia, Yanhong; Yi, Yujun; Li, Zhiwei; Wang, Zhaoyin; Zheng, Xiangmin
2017-09-01
Hydraulic geometry (HG) is an important geomorphic concept that has played an indispensable role in hydrological analyses, physical studies of streams, ecosystem and aquatic habitat studies, and sedimentology research. More than 60 years after Leopold and Maddock (1953) first introduced the concept of HG, researchers have still not uncovered the physical principles underlying HG behavior. One impediment is the complexity of the natural river cross section. The current study presents a new way to simplify the cross section, namely, the hydraulic equivalent section, which is generalized from the cross section in the ;gradually varied flow of an alluvial river; (GVFAR) and features hydrodynamic properties and bed-building laws similar to those of the GVFAR. Energy balance was used to derive the stage Z-discharge Q relationship in the GVFAR. The GVFAR in the Songhua River and the Yangtze River were selected as examples. The data, including measured discharge, river width, water stage, water depth, wet area, and cross section, were collected from the hydrological yearbooks of typical hydrological stations on the Songhua River and the Yangtze River from 1955 to 1987. The relationships between stage Z-discharge Q and cross-sectional area A-stage Z at various stations were analyzed, and ;at-a-station hydraulic geometry; (AHG) relationships were obtained in power-law forms. Based on derived results and observational data analysis, the Z-Q and Z-A relationships of AHG were similar to rectangular weir flows, thus the cross section of the GVFAR was generalized as a compound rectangular, hydraulic equivalent cross section. As to bed-building characteristics, the bankfull discharge method and the stage-discharge-relation method were used to calculate the dominant variables of the alluvial river. This hydraulic equivalent section has the same Z-Q relation, Z-A relation, dominant discharge, dominant river width, and dominant water depth as the cross section in the GVFAR. With the
张艳超; 何济洲
2014-01-01
在低耗散卡诺热机模型的基础上，进一步研究热漏对低耗散卡诺热机最大功率下效率及其边界的影响。在类卡诺热机循环条件下，考虑等温膨胀与等温压缩过程中高低温热源之间存在热漏，推导出存在热漏时低耗散卡诺热机最大功率下效率的表达式，并且在对称情况下与经典CA(Curzon-Ahlborn)效率进行比较。发现当不存在热漏时，低耗散卡诺热机最大功率下的效率等于CA效率。当存在热漏时，低耗散卡诺热机最大功率下的效率低于CA效率，并随着热漏的增加而降低。在非对称下得到存在热漏时低耗散卡诺热机最大功率下效率的上下限和可观测范围，并与不同种类实际的热机效率进行比较，结果表明考虑热漏时低耗散卡诺热机的效率及其边界更加符合实际热机的观测值。%Based on the low-dissipation Carnot heat engine model, the influence of heat leak on the efficiency at maximum power and its bounds of low-dissipation Carnot heat engine are further discussed. Under the condition of Carnot-like heat engine cycle, the expressions for the efficiency at maximum power of the quantum dot engine are derived in the presence of heat leak between hot reservoir and cold reservoir of the isothermal expansion and the isothermal compression process, and compared with the classical CA efficiency in the symmetric case. It is found that, when there is no heat leak, the efficiency at maximum power of the low-dissipation Carnot heat engine is equal to the CA efficiency. In the presence of heat leak, the efficiency at maximum power of the low-dissipation Carnot heat engine is lower than the CA efficiency, and decreases with the increases of heat leak. In the case of asymmetric, the upper bound and lower bound of efficiency at maximum power are obtained, and compared with different kinds of actual engine efficiency. The results show that the efficiency at maximum power and its
EFFECT OF HYDRAULIC AND GEOMETRICAL PROPERTIES ON STEPPED CASCADE AERATION SYSTEM
VEDHACHALAM RATHINAKUMAR
2017-03-01
Full Text Available Stepped cascade aeration system is commonly used to aerate the water and wastewater to increase the dissolved oxygen during pre and post treatment process. In the present research, experiments were conducted to evaluate the performance of a rectangular Cascade Aeration System with varying flow rates, risers and tread by maintaining constant width of the channel using water collected from reverse osmosis plant. The experiments were carried out with four different risers such as 0.15 m, 0.18 m, 0.225 m and 0.30 m. Each rise was investigated with five different tread of 0.60 m, 0.55 m, 0.50 m, 0.45 m and 0.40 m. Comprehensive experimental investigations were carried out for different hydraulic loading rates of 0.005 to 0.035 m3/s/m2. Results obtained from the experiments reveals that increasing dimensionless discharges promotes more aeration, attains a maximum up to dimensionless discharge= 2.22 and beyond this there was a significant decrease in aeration. In addition, the increased in number of steps significantly enhances air entertainment and surface fall rate in the Stepped Cascade Aeration System. A regression equation was derived by keeping aeration efficiency as response with dimensionless discharge and oxygen saturation concentration as influencing parameters. The dimension less discharge is a function of critical depth of the rectangular channel and step height, whereas oxygen saturation concentration represents the ratio of oxygen deficit and oxygen saturation concentration. Based on the experimental results, the optimum design and/or results such as number of steps (12 numbers and hydraulic loading rate (0.025 m3/s/m2 with fixed tread width of 0.6 m were identified to achieve maximum aeration rate (0.5-0.60 in Aeration system.
USE OF GEOSYNTHETIC CASINGS IN HYDRAULIC ENGINEERING
Piyavskiy Semen Avraamovich
2012-10-01
Full Text Available The article covers the use of geosynthetic casings in hydraulic engineering. The authors describe the structure of earth dams that have geosynthetic casings used as the reinforcement of downstream slopes. Results of stability calculations are provided. The authors consider several examples of effective application of advanced geosynthetic materials used in combination with local building materials as structural elements of hydraulic engineering facilities. Their analysis has demonstrated a strong potential and expediency of application of geosynthetic casings in the course of construction and renovation of low-pressure earth dams. The authors have also developed a new structure of an earth dam. The new earth dam has geosynthetic casings used as structural reinforcing elements of the crown and the downstream slope. The dam structure contemplates the overflow of high water. The structural strengths of the proposed solution include a smaller material consumption rate, lower labour intensiveness and cost of the slope reinforcement due to the application of local building materials used to fill the casings, fast and easy depositing of slope reinforcing elements, and high workability of its dismantling for repair purposes. The authors have also completed the analysis of stability of geosynthetic casings of downstream slopes of an earth dam. The analysis has proven high efficiency of a small slope ratio in combination with its anchorage and reinforcement of the downstream toe with the help of high-strength geogrids.
CRITICALITY CURVES FOR PLUTONIUM HYDRAULIC FLUID MIXTURES
WITTEKIND WD
2007-10-03
This Calculation Note performs and documents MCNP criticality calculations for plutonium (100% {sup 239}Pu) hydraulic fluid mixtures. Spherical geometry was used for these generalized criticality safety calculations and three geometries of neutron reflection are: {sm_bullet}bare, {sm_bullet}1 inch of hydraulic fluid, or {sm_bullet}12 inches of hydraulic fluid. This document shows the critical volume and critical mass for various concentrations of plutonium in hydraulic fluid. Between 1 and 2 gallons of hydraulic fluid were discovered in the bottom of HA-23S. This HA-23S hydraulic fluid was reported by engineering to be Fyrquel 220. The hydraulic fluid in GLovebox HA-23S is Fyrquel 220 which contains phosphorus. Critical spherical geometry in air is calculated with 0 in., 1 in., or 12 inches hydraulic fluid reflection.
DCS Hydraulics Submittal, Butler County, Alabama, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulics data includes spatial datasets and data tables necessary for documenting the hydraulic procedures for computing flood elevations for a flood insurance...
DCS Hydraulics Submittal, Bullock County, Alabama, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulics data includes spatial datasets and data tables necessary for documenting the hydraulic procedures for computing flood elevations for a flood insurance...
DCS Hydraulics Submittal, Covington County, Alabama, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulics data includes spatial datasets and data tables necessary for documenting the hydraulic procedures for computing flood elevations for a flood insurance...
High Pressure Hydraulic Distribution System
1991-05-20
to 500 0 F. 5 cycles. 5000 F room temperature to 50001F; 45 ______________ Icycles The tesis planned for the distribution system demonstrator were...American Society for Testing and Materials ASTM D412 - Tension Testing of Vulcanized Rubber ASTM D571 - Testing Automotive Hydraulic Brake Hose Society of
Bonn, D.; Andersen, Anders Peter; Bohr, Tomas
2009-01-01
We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected...
Hydraulic Fracture Containment in Sand
Dong, Y.
2010-01-01
The mechanism of hydraulic fracturing in soft, high permeability material is considered fundamentally different from that in hard, low permeability rock, where a tensile fracture is created and conventional linear elastic fracture mechanics (LEFM) applies. The fracturing and associated modeling work
Design of hydraulic recuperation unit
Jandourek Pavel
2016-01-01
Full Text Available This article deals with design and measurement of hydraulic recuperation unit. Recuperation unit consist of radial turbine and axial pump, which are coupled on the same shaft. Speed of shaft with impellers are 6000 1/min. For economic reasons, is design of recuperation unit performed using commercially manufactured propellers.
Tree Hydraulics: How Sap Rises
Denny, Mark
2012-01-01
Trees transport water from roots to crown--a height that can exceed 100 m. The physics of tree hydraulics can be conveyed with simple fluid dynamics based upon the Hagen-Poiseuille equation and Murray's law. Here the conduit structure is modelled as conical pipes and as branching pipes. The force required to lift sap is generated mostly by…
Tree Hydraulics: How Sap Rises
Denny, Mark
2012-01-01
Trees transport water from roots to crown--a height that can exceed 100 m. The physics of tree hydraulics can be conveyed with simple fluid dynamics based upon the Hagen-Poiseuille equation and Murray's law. Here the conduit structure is modelled as conical pipes and as branching pipes. The force required to lift sap is generated mostly by…
A new linear type hydraulic motor
Jiang, Dong; Zhang, Tong; Li, Wenhua; Chen, Xinyang
2017-08-01
This paper proposes the design of liner type hydraulic motor on the base of inner curved radial piston hydraulic motor. The hydraulic cylinders of the new type motor are in the straight line which will improve the utilization of the axial space and different out power can be supplied by changes the number of cylinders. In this paper, the structure and working principle of the liner type hydraulic motor is introduced.
Hsiao, Kai-Wen; Hsu, Yu-Chao; Jan, Chyan-Deng; Su, Yu-Wen
2016-04-01
The inclined rectangular chute construction is a common structure used in hydraulic engineering for typical reasons such as the increase of bottom slope, the transition from side channel intakes to tunnel spillways, the drainage construction, and the reduction of chute width due to bridges, flood diversion structures or irrigation systems. The converging vertical sidewalls of a chute contraction deflect the supercritical flow to form hydraulic shock waves. Hydraulic shock waves have narrow and locally extreme wavy surfaces, which commonly results in the requirement of higher height of sidewalls. Therefore, predicting the possible height and position of maximum hydraulic shock wave are necessary to design the required height of sidewalls to prevent flow overtopping. In this study, we used a three-dimensional computation fluid dynamics model (i.e., FLOW-3D) to simulate the characteristics of hydraulic shock waves in an inclined chute contraction. For this purpose, the parameters of simulated hydraulic shock wave, such as the shock angle, maximum shock wave height and maximum shock wave position in various conditions are compared with those calculated by the empirical relations obtained from literatures. We showed that the simulated results are extremely close to the experimental results. The numerical results validated the applicability of these empirical relations and extend their applicability to higher approach Froude numbers from 3.51 to 7.27. Furthermore, we also applied the Yuan-Shan-Tsu flood diversion channel under 200-year peak flow condition to FLOW-3D model to simulate the hydraulic shock waves and validate the effect of the installation of a diversion pier in the channel on promoting the stability of flow fluid. The results revealed that a diversion pier installed in the Yuan-Shan-Tsu flood diversion channel is helpful for improving the stability of flow field. In summary, this study demonstrates that FLOW-3D model can be used to simulate the
Almomani, Fares
2016-01-01
This study investigates the effect of hydraulic mixing on anaerobic digestion and sludge accumulation in a septic tank. The performance of a septic tank equipped with a hydraulic mixer was compared with that of a similar standard septic tank over a period of 10 months. The study was conducted in two phases: Phase-I--from May to November 2013 (6 months); Phase-II--from January to May 2014 (4 months). Hydraulic mixing effectively reduced the effluent biological oxygen demand (BOD) and total suspended solids, and reduced the sludge accumulation rate in the septic tank. The BOD removal efficiencies during Phase-II were 65% and 75% in the standard septic tank and a septic tank equipped with hydraulic mixer (Smart Digester™), respectively. The effect of hydraulic mixing reduced the rate of sludge accumulation from 0.64 cm/day to 0.27 cm/day, and increased the pump-out interval by a factor of 3.
Hydraulic characterization of " Furcraea andina
Rivera-Velasquez, M. F.; Fallico, C.; Molinari, A.; Santillan, P.; Salazar, M.
2012-04-01
The present level of pollution, increasingly involving groundwaters, constitutes a serious risk for environment and human health. Therefore the remediation of saturated and unsaturated soils, removing pollutant materials through innovative and economic bio-remediation techniques is more frequently required. Recent studies on natural fiber development have shown the effectiveness of these fibers for removal of some heavy metals, due to the lignin content in the natural fibers which plays an important role in the adsorption of metal cations (Lee et al., 2004; Troisi et al., 2008; C. Fallico, 2010). In the context of remediation techniques for unsaturated and/or saturated zone, an experimental approach for the hydraulic characterization of the "Furcraea andina" (i.e., Cabuya Blanca) fiber was carried out. This fiber is native to Andean regions and grows easily in wild or cultivated form in the valleys and hillsides of Colombia, Ecuador, and Peru. Fibers of "Furcraea andina" were characterized by experimental tests to determine their hydraulic conductivity or permeability and porosity in order to use this medium for bioremediation of contaminated aquifer exploiting the physical, chemical and microbial capacity of natural fiber in heavy metal adsorption. To evaluate empirically the hydraulic conductivity, laboratory tests were carried out at constant head specifically on the fibers manually extracted. For these tests we used a flow cell (used as permeameter), containing the "Furcraea andina" fibers to be characterized, suitably connected by a tygon pipe to a Marriott's bottle, which had a plastic tube that allow the adjustment of the hydraulic head for different tests to a constant value. By this experiment it was also possible to identify relationships that enable the estimation of permeability as a function of density, i.e. of the compaction degree of the fibers. Our study was carried out for three values of hydraulic head (H), namely 10, 18, and 25 cm and for each
14 CFR 25.1435 - Hydraulic systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hydraulic systems. 25.1435 Section 25.1435... STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1435 Hydraulic systems. (a) Element design. Each element of the hydraulic system must be designed to: (1) Withstand the proof...
14 CFR 27.1435 - Hydraulic systems.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hydraulic systems. 27.1435 Section 27.1435... STANDARDS: NORMAL CATEGORY ROTORCRAFT Equipment Safety Equipment § 27.1435 Hydraulic systems. (a) Design. Each hydraulic system and its elements must withstand, without yielding, any structural loads...
Hydraulic modelling for flood mapping and prevention: the case study of Cerfone River
Di Francesco, Silvia; Venturi, Sara; Manciola, Piergiorgio
2016-04-01
The research focuses on the hydraulic risk evaluation and danger estimation for different extreme flood events, in order to correctly implement mitigation measures in an anthropized basin. The Cerfone River (Tuscany, Italy), due to the several floods that have affected the neighbouring villages in recent years, is selected as case of study. A finite volume numerical model that solves the shallow water equations all over the computational domain, was used to simulate the unsteady evolution of the maximum extent of flooded areas for different scenarios. The one - dimensional approach (still widespread in engineering projects) can be inaccurate in complex flows, which are often two or three dimensional and sometimes does not manage to capture the flood spatial extents in terms of flow depth and velocity. The use of a two-dimensional numerical model seems to be the suitable instrument in terms of computational efficiency and adequacy of results. In fact it overcomes the limits of a one-dimensional modeling in terms of prediction of hydraulic variables with a less computational effort respect to a full 3d model. An accurate modeling of the river basin leads to the evaluation of the present hydraulic risk. Structural and non- structural measures are then studied, simulated and compared in order to define the optimal risk reduction plan for the area of study. At this aim, different flooding scenarios were simulated through the 2D mathematical model: i) existing state of the river and floodplain areas; ii) design of a levee to protect the most vulnerable populated areas against the flooding risk; iii) use of off - stream detention basins that strongly amplify the lamination capacity of floodplains. All these scenarios were simulated for different return periods: 50, 100, 200 and 500 years. The inputs of the hydraulic models are obtained in accordance with the legislative requirement of Tuscany Region; in particular discharge hydrographs are evaluate through the ALTo
Position Sensorless Drive o SRM Mounted on Hydraulic Pump Unit
Kosaka, Takashi; Nabeya, Yoshinari; Ohyama, Kazunobu; Matsui, Nobuyuki
Recently, Switched Reluctance Motors (SRM)have been applied to several industrial products such as fans, blowers, pumps and so forth because of their simple construction and relatively high e ciency.As one of the examples, Daikin Industries Ltd.has been successful in manufacturing hydraulic pump unit using 2.2kW three-phase SRM with shaft mounted position sensor for its control. This paper presents the position sensorless drive o the SRM for the purposes of reducing cost and down sizing of the hydraulic pump unit system.The controller, intentionally designed for this special application, realizes the following characteristics;the maximum and minimum speeds are 5000 and 300rpm, the speed response between the maximum and minimum speeds is within 100msec and the starting torque is less than 20% of the rated torque.The experimental studies using the hydraulic pump unit show that the proposed sensorless control scheme satis es the requirements for this application.
Incorporating Soil Hydraulic Parameter Statistics in Developing Pedo-transfer Functions
Zhao, Y.; Zhu, J.; Ye, M.; Meyer, P. D.; Pan, F.; Hassan, A. E.
2007-12-01
In this study, we develop artificial neural network (ANN) based pedotransfer functions (PTFs) to predict soil hydraulic properties. The PTF approach is an efficient way of translating less costly available data, such as particle-size distributions, soil textures and other geophysical measurements, to soil hydraulic parameters required for numerical simulations and other applications. The ANN PTFs need to be trained before being used to transfer indirect measurements to soil hydraulic parameters. The traditional training process, in general, is to adjust ANN's coefficients to solely minimize the difference between the estimated and measured soil hydraulic parameters. The training process, however, did not consider the distributions of soil hydraulic parameters and the trained neural networks may yield improper distributions, which may severely affect probabilistic predictions. We incorporate the distributions of the soil hydraulic parameters into the ANN PTF development. In addition, it has been observed that PTFs can introduce unrealistic correlations between the output parameters. The unwanted artificial correlations need to be penalized during the training process, since it is well known that parameter correlations have significant effect on predictions. We achieve these two goals by adding two regularization terms to the ANN objective functions. A suite of new neural network models are developed to estimate soil hydraulic parameters. These neural network models have the same input and output variables, but different objective functions, which incorporate sequentially the site soil hydraulic parameter measurements, parameter probability distributions, and parameter correlations.
Thermal Hydraulic Performance of Tight Lattice Bundle
Yamamoto, Yasushi; Akiba, Miyuki; Morooka, Shinichi; Shirakawa, Kenetsu; Abe, Nobuaki
Recently, the reduced moderation spectrum BWR has been studied. The fast neutron spectrum is obtained through triangular tight lattice fuel. However, there are few thermal hydraulic test data and thermal hydraulic correlation applicable to critical power prediction in such a tight lattice bundle. This study aims to enhance the database of the thermal hydraulic performance of the tight lattice bundle whose rod gap is about 1mm. Therefore, thermal hydraulic performance measurement tests of tight lattice bundles for the critical power, the pressure drop and the counter current flow limiting were performed. Moreover, the correlations to evaluate the thermal-hydraulic performance of the tight lattice bundle were developed.
Sefkow, Adam B.; Bennett, Guy R.
2010-09-01
Under the auspices of the Science of Extreme Environments LDRD program, a <2 year theoretical- and computational-physics study was performed (LDRD Project 130805) by Guy R Bennett (formally in Center-01600) and Adam B. Sefkow (Center-01600): To investigate novel target designs by which a short-pulse, PW-class beam could create a brighter K{alpha} x-ray source than by simple, direct-laser-irradiation of a flat foil; Direct-Foil-Irradiation (DFI). The computational studies - which are still ongoing at this writing - were performed primarily on the RedStorm supercomputer at Sandia National Laboratories Albuquerque site. The motivation for a higher efficiency K{alpha} emitter was very clear: as the backlighter flux for any x-ray imaging technique on the Z accelerator increases, the signal-to-noise and signal-to-background ratios improve. This ultimately allows the imaging system to reach its full quantitative potential as a diagnostic. Depending on the particular application/experiment this would imply, for example, that the system would have reached its full design spatial resolution and thus the capability to see features that might otherwise be indiscernible with a traditional DFI-like x-ray source. This LDRD began FY09 and ended FY10.
Establishment of digital model for dynamic simulation analysis on hydraulic impact perforator
无
2005-01-01
Hydraulic impact perforator is powerful tools for trenchless project. It has advantages in cabinet structure, low cost, long life and easy protected. Compared with pneumatic DTH, the hydraulic impact spear worked under high pressure and using uncompressible fluid thusgreater impact energy and higher efficiency can be supported. The authors founded the dynamic simulation model of HDI-146 hydraulic impact spear. The project for solving the differential equation was suggested also. By means of virtual machine technology, the dynamic mechanism of HDI-146 can be explored and tutoring us to optimize the structural parameters can be made.
Hydraulic fracture during epithelial stretching
Casares, Laura; Vincent, Romaric; Zalvidea, Dobryna; Campillo, Noelia; Navajas, Daniel; Arroyo, Marino; Trepat, Xavier
2015-03-01
The origin of fracture in epithelial cell sheets subject to stretch is commonly attributed to excess tension in the cells’ cytoskeleton, in the plasma membrane, or in cell-cell contacts. Here, we demonstrate that for a variety of synthetic and physiological hydrogel substrates the formation of epithelial cracks is caused by tissue stretching independently of epithelial tension. We show that the origin of the cracks is hydraulic; they result from a transient pressure build-up in the substrate during stretch and compression manoeuvres. After pressure equilibration, cracks heal readily through actomyosin-dependent mechanisms. The observed phenomenology is captured by the theory of poroelasticity, which predicts the size and healing dynamics of epithelial cracks as a function of the stiffness, geometry and composition of the hydrogel substrate. Our findings demonstrate that epithelial integrity is determined in a tension-independent manner by the coupling between tissue stretching and matrix hydraulics.
PRESSURE OSCILLATIONS IN TRANSIENT PROCESSES OF HYDRAULIC SYSTEMS WITH VARIABLE DISPLACEMENT PUMPS
Hennadii Zaionchkovskyi
2015-12-01
Full Text Available In aviation hydraulic drive of high power as a power supply the axial-piston variable displacement pumps became wide spreaded. The pump operational modes with air isolation and cavitation are accompanied by increased noise, delivery reduction and intensive pressure oscillations. The negative results of such phenomena are hydraulic elements erosion, pipeline fatigue failure, working fluid viscosity reduction and its contamination by wear products. The mechanism of cavitation rising in axial-piston pumps is considered, and factors which influence the cavitation rising and working fluid aeration are specified. The features of transient processes in aircraft hydraulic systems with variable displacement pumps are considered. It has been showed that as the pump delivery changes from its minimum to maximum great pressure oscillations in the aircraft pressure pipeline of the hydraulic system takes place, and have a negative influence on the pump service life. The recommendations concerning such pressure oscillation reduction are given.
2008-04-17
currently formulated with vegetable oils (i.e., rapeseed , sun flower, corn, soybean, canola, coconut, etc.) and synthetic ester, such as polyol ester...2008 Vegetable Oil • Excellent lubrication • Nontoxic • Biodegradable • Derived from renewable resources such as rapeseed , sunflower, corn...Mineral Oil 100 SAE 15W-40 G Rapeseed 32 Commercial HF H Polyol ester 22 MIL-PRF-32073 Grade 2 I Canola - Cooking Oil *Hydraulic fluid 3717 April
Fire Resistant Aircraft Hydraulic System.
1982-07-01
and compounds based on new experimental elastomers as well as most commercially available elastomers were screened in seeking seals that were both...for hydraulic component testing. All of the available E6.5 stock was purchased for the screening tests. However, DuPont stated that other homologs of...with the lubricity and anti-wear additive olyvan A (molybdenum oxysulphide dithiocarbamate ) added in the quantity of less than one percent by weight
The Sherpa Maximum Likelihood Estimator
Nguyen, D.; Doe, S.; Evans, I.; Hain, R.; Primini, F.
2011-07-01
A primary goal for the second release of the Chandra Source Catalog (CSC) is to include X-ray sources with as few as 5 photon counts detected in stacked observations of the same field, while maintaining acceptable detection efficiency and false source rates. Aggressive source detection methods will result in detection of many false positive source candidates. Candidate detections will then be sent to a new tool, the Maximum Likelihood Estimator (MLE), to evaluate the likelihood that a detection is a real source. MLE uses the Sherpa modeling and fitting engine to fit a model of a background and source to multiple overlapping candidate source regions. A background model is calculated by simultaneously fitting the observed photon flux in multiple background regions. This model is used to determine the quality of the fit statistic for a background-only hypothesis in the potential source region. The statistic for a background-plus-source hypothesis is calculated by adding a Gaussian source model convolved with the appropriate Chandra point spread function (PSF) and simultaneously fitting the observed photon flux in each observation in the stack. Since a candidate source may be located anywhere in the field of view of each stacked observation, a different PSF must be used for each observation because of the strong spatial dependence of the Chandra PSF. The likelihood of a valid source being detected is a function of the two statistics (for background alone, and for background-plus-source). The MLE tool is an extensible Python module with potential for use by the general Chandra user.
Research on hydraulic slotting technology controlling coal-gas outbursts
WEI Guo-ying; SHAN Zhi-yong; ZHANG Zi-min
2008-01-01
Measured to control serious coal-gas outburst in coal seam were analyzed by theory and experimented in test site. A new technique to distress the coal-bed and drain methane, called hydraulic slotting, was described in detail, and the mechanism of hydrau-lic slotting was put forward and analyzed. The characteristic parameter of hydraulic slotting was given in Jiaozuo mining area and the characteristic of validity, adaptability and secu-rity was evaluated. The results show that the stress surrounding the strata and the gas in coal seam is released efficiently and thoroughly while new techniques are taken, as slot-ting at heading face by high pressure large diameter jet. The resistance to coal and gas outbursts is increased dramatically once the area of slotting is increased to a certain size.In the process of driving 2 000 m tunnel by hydraulic slotting excavation, coal and gas outburst never occurre. The technique could be used to prevent and control potential coal-gas outburst in the proceeding of tunnel driving, and the speed tunneling could be as high as more than 2 times.
Simulation and control of an electro-hydraulic actuated clutch
Balau, Andreea-Elena; Caruntu, Constantin-Florin; Lazar, Corneliu
2011-08-01
The basic function of any type of automotive transmission is to transfer the engine torque to the vehicle with the desired ratio smoothly and efficiently and the most common control devices inside the transmission are clutches and hydraulic pistons. The automatic control of the clutch engagement plays a crucial role in Automatic Manual Transmission (AMT) vehicles, being seen as an increasingly important enabling technology for the automotive industry. It has a major role in automatic gear shifting and traction control for improved safety, drivability and comfort and, at the same time, for fuel economy. In this paper, a model for a wet clutch actuated by an electro-hydraulic valve used by Volkswagen for automatic transmissions is presented. Starting from the developed model, a simulator was implemented in Matlab/Simulink and the model was validated against data obtained from a test-bench provided by Continental Automotive Romania, which includes the Volkswagen wet clutch actuated by the electro-hydraulic valve. Then, a predictive control strategy is applied to the model of the electro-hydraulic actuated clutch with the aims of controlling the clutch piston displacement and decreasing the influence of the network-induced delays on the control performances. The simulation results obtained with the proposed method are compared with the ones obtained with different networked controllers and it is shown that the strategy proposed in this paper can indeed improve the performances of the control system.
Pump Application as Hydraulic Turbine – Pump as Turbine (PaT)
Rusovs, D
2009-01-01
The paper considers pump operation as hydraulic turbine with purpose to produce mechanical power from liquid flow. The Francis hydraulic turbine was selected for comparison with centrifugal pump in reverse operation. Turbine and centrifugal pump velocity triangles were considered with purpose to evaluate PaT efficiency. Shape of impeller blades for turbine and pumps was analysed. Specific speed calculation is carried out with purpose to obtain similarity in pump and turbine description. For ...
Hydraulic Redistribution: A Modeling Perspective
Daly, E.; Verma, P.; Loheide, S. P., III
2014-12-01
Roots play a key role in the soil water balance. They extract and transport water for transpiration, which usually represents the most important soil water loss in vegetated areas, and can redistribute soil water, thereby increasing transpiration rates and enhancing root nutrient uptake. We present here a two-dimensional model capable of describing two key aspects of root water uptake: root water compensation and hydraulic redistribution. Root water compensation is the ability of root systems to respond to the reduction of water uptake from areas of the soil with low soil water potential by increasing the water uptake from the roots in soil parts with higher water potential. Hydraulic redistribution is a passive transfer of water through the root system from areas of the soil with greater water potential to areas with lower water potential. Both mechanisms are driven by gradients of water potential in the soil and the roots. The inclusion of root water compensation and hydraulic redistribution in models can be achieved by describing root water uptake as a function of the difference in water potential between soil and root xylem. We use a model comprising the Richards equation for the water flow in variably saturated soils and the Darcy's equation for the water flow in the xylem. The two equations are coupled via a sink term, which is assumed to be proportional to the difference between soil and xylem water potentials. The model is applied in two case studies to describe vertical and horizontal hydraulic redistribution and the interaction between vegetation with different root depths. In the case of horizontal redistribution, the model is used to reproduce the fluxes of water across the root system of a tree subjected to uneven irrigation. This example can be extended to situations when only part of the root system has access to water, such as vegetation near creeks, trees at the edge of forests, and street trees in urban areas. The second case is inspired by recent
Engineering rhizosphere hydraulics: pathways to improve plant adaptation to drought
Ahmed, Mutez; Zarebanadkouki, Mohsen; Ahmadi, Katayoun; Kroener, Eva; Kostka, Stanley; Carminati, Andrea
2017-04-01
Developing new technologies to optimize the use of water in irrigated croplands is of increasing importance. Recent studies have drawn attention to the role of mucilage in shaping rhizosphere hydraulic properties and regulating root water uptake. During drying mucilage keeps the rhizosphere wet and conductive, but upon drying it turns hydrophobic limiting root water uptake. Here we introduced the concept of rhizoligands, defined as additives that 1) rewet the rhizosphere and 2) reduce mucilage swelling hereby reducing the rhizosphere conductivity. We then tested its effect on rhizosphere water dynamics and transpiration. The following experiments were carried out to test if selected surfactants behave as a rhizoligand. We used neutron radiography to monitor water redistribution in the rhizosphere of lupine and maize irrigated with water and rhizoligand solution. In a parallel experiment, we tested the effect of rhizoligand on the transpiration rate of lupine and maize subjected to repeated drying and wetting cycles. We also measured the effect of rhizoligand on the maximum swelling of mucilage and the saturated hydraulic conductivity of soil mixed with various mucilage concentrations. The results were then simulated using a root water uptake model. Rhizoligand treatment quickly and uniformly rewetted the rhizosphere of maize and lupine. Interestingly, rhizoligand also reduced transpiration during drying/wetting cycles. Evaporation from the bare soil was of minor importance. Our hypothesis is that the reduction in transpiration was triggered by the interaction between rhizoligand and mucilage exuded by roots. This hypothesis is supported by the fact that rhizoligand reduced the maximum swelling of mucilage, increased its viscosity, and decreased the hydraulic conductivity of soil-mucilage mixtures. The reduced conductivity of the rhizosphere induced a moderate stress to the plants reducing transpiration. Simulation with a reduced hydraulic conductivity of the
Thermal-hydraulic analysis of LTS cables for the DEMO TF coil using simplified models
Lewandowska Monika
2017-03-01
Full Text Available The conceptual design activities for the DEMOnstration reactor (DEMO – the prototype fusion power plant – are conducted in Europe by the EUROfusion Consortium. In 2015, three design concepts of the DEMO toroidal field (TF coil were proposed by Swiss Plasma Center (EPFL-SPC, PSI Villigen, Italian National Agency for New Technologies (ENEA Frascati, and Atomic Energy and Alternative Energies Commission (CEA Cadarache. The proposed conductor designs were subjected to complete mechanical, electromagnetic, and thermal-hydraulic analyses. The present study is focused on the thermal-hydraulic analysis of the candidate conductor designs using simplified models. It includes (a hydraulic analysis, (b heat removal analysis, and (c assessment of the maximum temperature and the maximum pressure in each conductor during quench. The performed analysis, aimed at verification whether the proposed design concepts fulfil the established acceptance criteria, provides the information for further improvements of the coil and conductors design.
Journal: Efficient Hydrologic Tracer-Test Design for Tracer ...
Hydrological tracer testing is the most reliable diagnostic technique available for the determination of basic hydraulic and geometric parameters necessary for establishing operative solute-transport processes. Tracer-test design can be difficult because of a lack of prior knowledge of the basic hydraulic and geometric parameters desired and the appropriate tracer mass to release. A new efficient hydrologic tracer-test design (EHTD) methodology has been developed to facilitate the design of tracer tests by root determination of the one-dimensional advection-dispersion equation (ADE) using a preset average tracer concentration which provides a theoretical basis for an estimate of necessary tracer mass. The method uses basic measured field parameters (e.g., discharge, distance, cross-sectional area) that are combined in functional relatipnships that descrive solute-transport processes related to flow velocity and time of travel. These initial estimates for time of travel and velocity are then applied to a hypothetical continuous stirred tank reactor (CSTR) as an analog for the hydrological-flow system to develop initial estimates for tracer concentration, tracer mass, and axial dispersion. Application of the predicted tracer mass with the hydraulic and geometric parameters in the ADE allows for an approximation of initial sample-collection time and subsequent sample-collection frequency where a maximum of 65 samples were determined to be necessary for descri
Farhang Azarang
2017-06-01
Full Text Available Introduction: The critical role of the rivers in supplying water for various needs of life has led to engineering identification of the hydraulic regime and flow condition of the rivers. Hydraulic structures such dams have inevitable effects on their downstream that should be well investigated. The reservoir dams are the most important hydraulic structures which are the cause of great changes in river flow conditions. Materials and Methods: In this research, an accurate assessment was performed to study the flow regime of Karkheh river at downstream of Karkheh Reservoir Dam as the largest dam in Middle East. Karkheh River is the third waterful river of Iran after Karun and Dez and the third longest river after the Karun and Sefidrud. The Karkheh Dam is a large reservoir dam built in Iran on the Karkheh River in 2000. The Karkheh Reservoir Dam is on the Karkheh River in the Northwestern Khouzestan Province, the closest city being Andimeshk to the east. The part of Karkheh River, which was studied in this research is located at downstream of Karkheh Reservoir Dam. This interval is approximately 94 km, which is located between PayePol and Abdolkhan hydrometric stations. In this research, 138 cross sections were used along Karkheh River. Distance of cross sections from each other was 680m in average. The efficient model of HEC-RAS has been utilized to simulate the Karkheh flow conditions before and after the reservoir dam construction using of hydrometric stations data included annually and monthly mean discharges, instantaneous maximum discharges, water surface profiles and etc. Three defined discharges had been chosen to simulate the Karkheh River flow; maximum defined discharge, mean defined discharge and minimum defined discharge. For each of these discharges values, HEC-RAS model was implemented as a steady flow of the Karkheh River at river reach of study. Water surface profiles of flow, hydraulic parameters and other results of flow regime in
On the application of reynolds theory to thermo-piezo-viscous lubrication in oil hydraulics
Johansen, Per; Roemer, Daniel Beck; Andersen, Torben O.
2015-01-01
. In this paper the derivation of Reynolds equation from the continuum assumption is reviewed and it is shown that the validity of Reynolds theory based pressure field solutions in oil hydraulic thermo-piezo-viscous lubrication models are subject to maximum bounds on the pressure and temperature field gradients...
Influence of the Geometry of Beveled Edges on the Stress-Strain State of Hydraulic Cylinders
Buyalich, G. B.; Anuchin, A. V.; Serikov, K. P.
2016-04-01
The studies were carried out to determine the influence of forms obtained when preparing edges for welding a cylinder for hydraulic legs; the maximum stresses were defined at the location of weld roots, depending on variable parameters. The stress-strain states were calculated using finite element method.
Identification of Physical Parameters for A Hydraulic Robot
Madsen, Henrik; Zhou, Jianjun; Hansen, Lars Henrik
1997-01-01
This paper describes a case study of identifying the physical model of a hydraulic test robot. The obtained model is intended to provide a basis for model-based control of the robot. The physical model is formulated in continuous time and is derived by application of the laws of physics...... on the system. The unknown (or uncertain) parameters are estimated with Maximum Likelihood (ML) parameter estimation. The identified model has been evaluated by comparing the measurements with simulation of the model. The identified model was much more capable of describing the dynamics of the system than...... the deterministic model....
Determination and discussion hydraulic retention time in membrane bioreactor system
无
2002-01-01
Based on the microorganism kinetic model, the formulafor computing hydraulic retention time in a membrane bioreactorsystem (MBR) is derived. With considering HRT as an evaluationindex a combinational approach was used to discuss factors whichhave an effect on MBR. As a result, the influencing factors werelisted in order from strength to weakness as: maximum specificremoval rate K, saturation constant Ks, maintenance coefficient m,Moreover, the formula was simplified, whose parameters wereexperimentally determined in petrochemical wastewater treatment. The simplified formula is (=1.1((1/(-1)(Ks+S)/KX0, forpetrochemical wastewater treatment K and Ks equaled 0.185 and154.2, respectively.
An Interval Maximum Entropy Method for Quadratic Programming Problem
RUI Wen-juan; CAO De-xin; SONG Xie-wu
2005-01-01
With the idea of maximum entropy function and penalty function methods, we transform the quadratic programming problem into an unconstrained differentiable optimization problem, discuss the interval extension of the maximum entropy function, provide the region deletion test rules and design an interval maximum entropy algorithm for quadratic programming problem. The convergence of the method is proved and numerical results are presented. Both theoretical and numerical results show that the method is reliable and efficient.
Vibrations of hydraulic pump and their solution
Dobšáková Lenka; Nováková Naděžda; Habán Vladimír; Hudec Martin; Jandourek Pavel
2017-01-01
The vibrations of hydraulic pump and connected pipeline system are very problematic and often hardly soluble. The high pressure pulsations of hydraulic pump with the double suction inlet are investigated. For that reason the static pressure and accelerations are measured. The numerical simulations are carried out in order to correlate computed data with experimental ones and assess the main source of vibrations. Consequently the design optimization of the inner hydraulic part of pump is done ...
Development and industrial tests of the first LNG hydraulic turbine system in China
Jie Chen
2016-10-01
Full Text Available The cryogenic hydraulic turbine can be used to replace the conventional J–T valve for LNG or mixed refrigerant throttling and depressurization in a natural gas liquefaction plant. This advanced technology is not only to enhance the efficiency of the liquefaction plant, but to usher a new trend in the development of global liquefaction technologies. China has over 136 liquefaction plants, but the cryogenic hydraulic turbines have not been deployed in industrial utilization. In addition, these turbines cannot be manufactured domestically. In this circumstance, through working on the key technologies for LNG hydraulic turbine process & control system development, hydraulic model optimization design, structure design and manufacturing, the first domestic cryogenic hydraulic turbine with a flow rate of 40 m3/h was developed to recover the pressure energy from the LNG of cold box. The turbine was installed in the CNOOC Zhuhai Natural Gas Liquefaction Plant for industrial tests under multiple working conditions, including start-stop, variable flow rates and variable rotation speeds. Test results show that the domestic LNG cryogenic hydraulic turbine has satisfactory mechanical and operational performances at low temperatures as specified in design. In addition, the process & control system and frequency-conversion power-generation system of the turbine system are designed properly to automatically and smoothly replace the existing LNG J–T valve. As a result, the domestic LNG cryogenic hydraulic turbine system can improve LNG production by an average of 2% and generate power of 8.3 kW.
Combining 3D Hydraulic Tomography with Tracer Tests for Improved Transport Characterization.
Sanchez-León, E; Leven, C; Haslauer, C P; Cirpka, O A
2016-07-01
Hydraulic tomography (HT) is a method for resolving the spatial distribution of hydraulic parameters to some extent, but many details important for solute transport usually remain unresolved. We present a methodology to improve solute transport predictions by combining data from HT with the breakthrough curve (BTC) of a single forced-gradient tracer test. We estimated the three dimensional (3D) hydraulic-conductivity field in an alluvial aquifer by inverting tomographic pumping tests performed at the Hydrogeological Research Site Lauswiesen close to Tübingen, Germany, using a regularized pilot-point method. We compared the estimated parameter field to available profiles of hydraulic-conductivity variations from direct-push injection logging (DPIL), and validated the hydraulic-conductivity field with hydraulic-head measurements of tests not used in the inversion. After validation, spatially uniform parameters for dual-domain transport were estimated by fitting tracer data collected during a forced-gradient tracer test. The dual-domain assumption was used to parameterize effects of the unresolved heterogeneity of the aquifer and deemed necessary to fit the shape of the BTC using reasonable parameter values. The estimated hydraulic-conductivity field and transport parameters were subsequently used to successfully predict a second independent tracer test. Our work provides an efficient and practical approach to predict solute transport in heterogeneous aquifers without performing elaborate field tracer tests with a tomographic layout.
Hydraulically Driven Grips For Hot Tensile Specimens
Bird, R. Keith; Johnson, George W.
1994-01-01
Pair of grips for tensile and compressive test specimens operate at temperatures up to 1,500 degrees F. Grips include wedges holding specimen inside furnace, where heated to uniform temperature. Hydraulic pistons drive wedges, causing them to exert clamping force. Hydraulic pistons and hydraulic fluid remain outside furnace, at room temperature. Cooling water flows through parts of grips to reduce heat transferred to external components. Advantages over older devices for gripping specimens in high-temperature tests; no need to drill holes in specimens, maintains constant gripping force on specimens, and heated to same temperature as that of specimen without risk of heating hydraulic fluid and acuator components.
OECD Maximum Residue Limit Calculator
With the goal of harmonizing the calculation of maximum residue limits (MRLs) across the Organisation for Economic Cooperation and Development, the OECD has developed an MRL Calculator. View the calculator.
Design of a wind turbine rotor for maximum aerodynamic efficiency
Johansen, Jeppe; Aagaard Madsen, Helge; Gaunaa, Mac;
2009-01-01
The design of a three-bladed wind turbine rotor is described, where the main focus has been highest possible mechanical power coefficient, CP, at a single operational condition. Structural, as well as off-design, issues are not considered, leading to a purely theoretical design for investigating...... and a full three-dimensional Navier-Stokes solver. Excellent agreement is obtained using the three models. Global CP reaches a value of slightly above 0.51, while global thrust coefficient CT is 0.87. The local power coefficient Cp increases to slightly above the Betz limit on the inner part of the rotor......; the local thrust coefficient Ct increases to a value above 1.1. This agrees well with the theory of de Vries, which states that including the effect of the low pressure behind the centre of the rotor stemming from the increased rotation, both Cp and Ct will increase towards the root. Towards the tip, both...
Efficient estimation of the maximum metabolic productivity of batch systems
St. John, Peter C.; Crowley, Michael F.; Bomble, Yannick J.
2017-01-31
Production of chemicals from engineered organisms in a batch culture involves an inherent trade-off between productivity, yield, and titer. Existing strategies for strain design typically focus on designing mutations that achieve the highest yield possible while maintaining growth viability. While these methods are computationally tractable, an optimum productivity could be achieved by a dynamic strategy in which the intracellular division of resources is permitted to change with time. New methods for the design and implementation of dynamic microbial processes, both computational and experimental, have therefore been explored to maximize productivity. However, solving for the optimal metabolic behavior under the assumption that all fluxes in the cell are free to vary is a challenging numerical task. Previous studies have therefore typically focused on simpler strategies that are more feasible to implement in practice, such as the time-dependent control of a single flux or control variable.
Design and Analysis of Hydraulic Chassis with Obstacle Avoidance Function
Hong, Yingjie; Zhang, Xiang
2017-07-01
This article mainly expounds the design of hydraulic system for the hydraulic chassis with obstacle avoidance function. Including the selection of hydraulic motor wheels, hydraulic pump, digital hydraulic cylinder and the matching of engine power. And briefly introduces the principle of obstacle avoidance.
Xue, Wei; Nay-Htoon, Bhone; Lindner, Steve; Dubbert, Maren; Otieno, Dennis; Ko, Jonghan; Werner, Christiane; Tenhunen, John
2016-04-01
Leaf intrinsic water use efficiency (WUEi) coupling maximum assimilation rate (Amax) and transpirable water lost via stomatal conductance (gsc) has been gaining increasing concern in sustainable crop production. Factors that influence leaf Amax and WUEi in rice (Oryza sativa L. cv Unkang) at flooding and rainfed conditions were evaluated. Positive correlations for leaf nitrogen content (Nm) and maximum carboxylation rate (Vcmax), for nitrogen allocation in Rubisco enzymes and mesophyll conductance (gm) were evident independent of cropping cultures. Rainfed rice exhibited enriched canopy leaf average Nm resulting in higher Amax, partially supporting improved leaf WUEi. Maximum WUEi (up to 0.14 μmol mmol(-1)) recorded in rainfed rice under drought conditions resulted from increasing gm/gsc ratio while at cost of significant decline in Amax due to hydraulically constrained gsc. Amax sensitivity related to gsc which was regulated by plant hydraulic conductance. WUEi was tightly correlated to Vcmax/gsc and gm/gsc ratios across the paddy and rainfed not to light environment, morphological and physiological traits, highlighting enhance capacity of Nm accumulation in rainfed rice with gsc at moderately high level similar to paddy rice facilitate optimization in Amax and WUEi while, is challenged by drought-vulnerable plant hydraulic conductance.
Nonlinear mathematical modeling and sensitivity analysis of hydraulic drive unit
Kong, Xiangdong; Yu, Bin; Quan, Lingxiao; Ba, Kaixian; Wu, Liujie
2015-09-01
The previous sensitivity analysis researches are not accurate enough and also have the limited reference value, because those mathematical models are relatively simple and the change of the load and the initial displacement changes of the piston are ignored, even experiment verification is not conducted. Therefore, in view of deficiencies above, a nonlinear mathematical model is established in this paper, including dynamic characteristics of servo valve, nonlinear characteristics of pressure-flow, initial displacement of servo cylinder piston and friction nonlinearity. The transfer function block diagram is built for the hydraulic drive unit closed loop position control, as well as the state equations. Through deriving the time-varying coefficient items matrix and time-varying free items matrix of sensitivity equations respectively, the expression of sensitivity equations based on the nonlinear mathematical model are obtained. According to structure parameters of hydraulic drive unit, working parameters, fluid transmission characteristics and measured friction-velocity curves, the simulation analysis of hydraulic drive unit is completed on the MATLAB/Simulink simulation platform with the displacement step 2 mm, 5 mm and 10 mm, respectively. The simulation results indicate that the developed nonlinear mathematical model is sufficient by comparing the characteristic curves of experimental step response and simulation step response under different constant load. Then, the sensitivity function time-history curves of seventeen parameters are obtained, basing on each state vector time-history curve of step response characteristic. The maximum value of displacement variation percentage and the sum of displacement variation absolute values in the sampling time are both taken as sensitivity indexes. The sensitivity indexes values above are calculated and shown visually in histograms under different working conditions, and change rules are analyzed. Then the sensitivity
PRINCIPLE OF POST-PRODUCTION DESIGN OF HYDRAULIC ACTUATORS
A. V. Puzanov
2015-01-01
Full Text Available In work the problem of design-technology preparation of production of hydraulic actuators is staticized. The structure and business processes of design and production are analysed. Methods and means of reorganization of project works for the purpose of cutting-down of time of preparation of production are offered. The directions of reorganization of process of design are formulated. The principle of carrying out procedures of design-technology preparation of production of hydraulic actuators with use of ready elements of a production cycle is considered. The scheme of their practical realization at machine-building enterprise is offered. The assessment of growth of efficiency of design-technology preparation of production is given in machine-building enterprise.
Helical coil thermal hydraulic model
Caramello, M.; Bertani, C.; De Salve, M.; Panella, B.
2014-11-01
A model has been developed in Matlab environment for the thermal hydraulic analysis of helical coil and shell steam generators. The model considers the internal flow inside one helix and its associated control volume of water on the external side, both characterized by their inlet thermodynamic conditions and the characteristic geometry data. The model evaluates the behaviour of the thermal-hydraulic parameters of the two fluids, such as temperature, pressure, heat transfer coefficients, flow quality, void fraction and heat flux. The evaluation of the heat transfer coefficients as well as the pressure drops has been performed by means of the most validated literature correlations. The model has been applied to one of the steam generators of the IRIS modular reactor and a comparison has been performed with the RELAP5/Mod.3.3 code applied to an inclined straight pipe that has the same length and the same elevation change between inlet and outlet of the real helix. The predictions of the developed model and RELAP5/Mod.3.3 code are in fairly good agreement before the dryout region, while the dryout front inside the helical pipes is predicted at a lower distance from inlet by the model.
Zhaobin Zhang
2016-09-01
Full Text Available As hydraulic fracturing is a fluid-rock coupling process, the permeability of the hydraulic-stimulated fracture network in the initial stage has great effects on the propagation of the hydraulic fracture network in the following stages. In this work, the permeability of the hydraulic-stimulated fracture network in shale gas reservoirs is investigated by a newly-proposed model based on the displacement discontinuity method. The permeability of the fracture network relies heavily on fracture apertures, which can be calculated with high precision by the displacement discontinuity method. The hydraulic fracturing processes are simulated based on the natural fracture networks reconstructed from the shale samples in the Longmaxi formation of China. The flow fields are simulated and the permeability is calculated based on the fracture configurations and fracture apertures after hydraulic fracturing treatment. It is found that the anisotropy of the permeability is very strong, and the permeability curves have similar shapes. Therefore, a fitting equation of the permeability curve is given for convenient use in the future. The permeability curves under different fluid pressures and crustal stress directions are obtained. The results show that the permeability anisotropy is stronger when the fluid pressure is higher. Moreover, the permeability anisotropy reaches the minimum value when the maximum principle stress direction is perpendicular to the main natural fracture direction. The investigation on the permeability is useful for answering how the reservoirs are hydraulically stimulated and is useful for predicting the propagation behaviors of the hydraulic fracture network in shale gas reservoirs.
Research on Discharge Circuit of Electro-Hydraulic Power Impulse Water Jets
Wang, Zhaohui; Gao, Quanjie; Wang, Wei; Liao, Zhenfang
2012-01-01
Electro-hydraulic power impulse water jets can convert the shock wave generated in the liquid by discharging into mechanical energy, and it has been widely used in material forming, surface cleaning, pipeline dirt cleaning and ore breaking process. Compared with the traditional high pressure water jets, the energy utilization of electro-hydraulic power impulse water jets is up to 80% while the water consumption is reduced by 40-55%. This paper has taken electro-hydraulic power impulse water jets as the research object, employed obtaining the maximum pressure of compression impulse matrix surface as the research goal, studied in depth the equivalent discharge circuit, characteristic equation and the relationship between the electrical parameters of the electro-hydraulic power impulse discharge circuit and built the calculation method of the voltage, the inductance, the capacitance and the electrode spacing parameter of electro-hydraulic power impulse water jets discharge circuit. So, it will provide important theoretical basis for further studies of electro-hydraulic power impulse technology and the existing water jets device.
Llanos, Ella María; Jeffrey, Robert G.; Hillis, Richard; Zhang, Xi
2017-08-01
Rocks are naturally fractured, and lack of knowledge of hydraulic fracture growth through the pre-existing discontinuities in rocks has impeded enhancing hydrocarbon extraction. This paper presents experimental results from uniaxial and biaxial tests, combined with numerical and analytical modelling results to develop a criterion for predicting whether a hydraulic fracture will cross a discontinuity, represented at the laboratory by unbonded machined frictional interfaces. The experimental results provide the first evidence for the impact of viscous fluid flow on the orthogonal fracture crossing. The fracture elliptical footprint also reflects the importance of both the applied loading stress and the viscosity in fracture propagation. The hydraulic fractures extend both in the direction of maximum compressive stress and in the direction with discontinuities that are arranged to be normal to the maximum compressive stress. The modelling results of fracture growth across discontinuities are obtained for the locations of slip starting points in initiating fracture crossing. Our analysis, in contrast to previous work on the prediction of frictional crossing, includes the non-singular stresses generated by the finite pressurised hydraulic fracture. Experimental and theoretical outcomes herein suggest that hydraulic fracture growth through an orthogonal discontinuity does not depend primarily on the interface friction coefficient.
Design of a New Energy-saving Hydraulic Cylinder%一种新型节能液压缸的设计
田灵飞; 陈龙淼
2011-01-01
In order to improve the efficiency of hydraulic cylinder, on the basis of improving hydraulic cylinder structure and hydraulic circuit design, a new energy-saving hydraulic cylinders was designed which was a combination of piston-cylinder and plungercylinder.The hydraulic cylinder has the characteristics of saving energy and improving the efficiency of hydraulic system.%为提高液压缸的工作效率,从改进液压缸结构以及液压回路的设计出发,设计一种基于柱塞缸与活塞缸的组合式新型节能高效液压缸.使用该液压缸既能节约液压能,又能提高液压系统效率.
Matzner, Steven L; Rettedal, David D; Harmon, Derek A; Beukelman, MacKenzie R
2014-08-01
Two cultivars of Phaseolus vulgaris L. were grown under three light levels to determine if hydraulic acclimation to light occurs in herbaceous annuals and whether intraspecific trade-offs constrain hydraulic traits. Acclimation occurred in response to reduced light and included decreased stomatal density (SD) and increased specific leaf area (SLA). Reduced light resulted in lower wood density (WD); decreased cavitation resistance, measured as the xylem pressure causing a 50 % reduction in stem conductivity (P50); and increased hydraulic capacity, measured as average leaf mass specific transpiration (E(LM)). Significant or marginally significant trade-offs between P50 and WD, WD and E(LM), and E(LM) and P50 reflected variation due to both genotype and environmental effects. A trade-off between WD and P50 within one cultivar indicated that morphological adjustment was constrained. Coordinated changes in WD, P50, and E(LM) within each cultivar in response to light were consistent with trade-offs constraining plasticity. A water-use efficiency (WUE, measured as δ(13)C) versus hydraulic capacity (E(LM)) trade-off was observed within each cultivar, further indicating that hydraulic trade-offs can constrain acclimation. Larger plants had lower hydraulic capacity (E(LM)) but greater cavitation resistance, WD, and WUE. Distinct hydraulic strategies were observed with the cultivar adapted to irrigated conditions having higher stomatal conductance and stem flow rates. The cultivar adapted to rain-fed conditions had higher leaf area and greater cavitation resistance. Hydraulic trade-offs were observed within the herbaceous P. vulgaris resulting from both genotype and environmental effects. Trade-offs within a cultivar reflected constraints to hydraulic acclimation in response to changing light.
Shang-Shu Shih
2016-06-01
Full Text Available Constructed ponds and wetlands are widely used in urban areas for stormwater management, ecological conservation, and pollution treatment. The treatment efficiency of these systems is strongly related to the hydrodynamics and hydraulic residence time. In this study, we developed a physical model and used rhodamine-WT as a tracer to conduct flume experiments. An equivalent Reynolds number was assumed, and the flume was a 1/25-scale model. Emergent obstructions (EOs, submerged obstructions (SOs, and high- and low-density emergent vegetation were placed along the sides of the flume, and 49 tracer tests were performed. We altered the density, spatial extent, aspect ratio, and configurations of the obstructions and emergent vegetation to observe changes in the hydraulic efficiency of a deep-water wetland. In the cases of low-aspect-ratio obstructions, the effects of the EOs on the hydraulic efficiency were significantly stronger than those of the SOs. In contrast, in the cases of high-aspect-ratio obstructions, the improvement effects of the EOs were weaker than those of the SOs. The high-aspect-ratio EOs altered the flow direction and constrained the water conveyance area, which apparently caused a short-circuited flow phenomenon, resulting in a decrease in hydraulic efficiency. Most cases revealed that the emergent vegetation improved the hydraulic efficiency more than the EOs. The high-density emergent vegetation (HEV improved the hydraulic efficiency more than the low-density emergent vegetation (LEV. Three cases involving HEV, two cases involving LEV, and one case involving EOs attained a good hydraulic efficiency (λ > 0.75. To achieve greater water purification, aquatic planting in constructed wetlands should not be overly dense. The HEV configuration in case 3-1 achieved optimum hydraulic performance for compliance with applicable water treatment standards.
Maximum margin Bayesian network classifiers.
Pernkopf, Franz; Wohlmayr, Michael; Tschiatschek, Sebastian
2012-03-01
We present a maximum margin parameter learning algorithm for Bayesian network classifiers using a conjugate gradient (CG) method for optimization. In contrast to previous approaches, we maintain the normalization constraints on the parameters of the Bayesian network during optimization, i.e., the probabilistic interpretation of the model is not lost. This enables us to handle missing features in discriminatively optimized Bayesian networks. In experiments, we compare the classification performance of maximum margin parameter learning to conditional likelihood and maximum likelihood learning approaches. Discriminative parameter learning significantly outperforms generative maximum likelihood estimation for naive Bayes and tree augmented naive Bayes structures on all considered data sets. Furthermore, maximizing the margin dominates the conditional likelihood approach in terms of classification performance in most cases. We provide results for a recently proposed maximum margin optimization approach based on convex relaxation. While the classification results are highly similar, our CG-based optimization is computationally up to orders of magnitude faster. Margin-optimized Bayesian network classifiers achieve classification performance comparable to support vector machines (SVMs) using fewer parameters. Moreover, we show that unanticipated missing feature values during classification can be easily processed by discriminatively optimized Bayesian network classifiers, a case where discriminative classifiers usually require mechanisms to complete unknown feature values in the data first.
Maximum Entropy in Drug Discovery
Chih-Yuan Tseng
2014-07-01
Full Text Available Drug discovery applies multidisciplinary approaches either experimentally, computationally or both ways to identify lead compounds to treat various diseases. While conventional approaches have yielded many US Food and Drug Administration (FDA-approved drugs, researchers continue investigating and designing better approaches to increase the success rate in the discovery process. In this article, we provide an overview of the current strategies and point out where and how the method of maximum entropy has been introduced in this area. The maximum entropy principle has its root in thermodynamics, yet since Jaynes’ pioneering work in the 1950s, the maximum entropy principle has not only been used as a physics law, but also as a reasoning tool that allows us to process information in hand with the least bias. Its applicability in various disciplines has been abundantly demonstrated. We give several examples of applications of maximum entropy in different stages of drug discovery. Finally, we discuss a promising new direction in drug discovery that is likely to hinge on the ways of utilizing maximum entropy.
HYDRAULIC CHARACTERISTICS OF VERTICAL VORTEX AT HYDRAULIC INTAKES
CHEN Yun-liang; WU Chao; YE Mao; JU Xiao-ming
2007-01-01
The trace of vertical vortex flow at hydraulic intakes is of the shape of spiral lines, which was observed in the presented experiments with the tracer technique. It represents the fluid particles flow spirally from the water surface to the underwater and rotate around the vortex-axis multi-cycle. This process is similar to the movement of screw. To describe the multi-circle spiral characteristics under the axisymmetric condition, the vertical vortex would change not only in the radial direction but also in the axial direction. The improved formulae for three velocity components for the vertical vortex flow were deduced by using the method of separation of variables in this article. In the improved formulae, the velocity components are the functions of the radial and axial coordinates, so the multi-circle spiral flow of vertical vortex could be simulated. The calculated and measured results for the vertical vortex flow were compared and the causes of errors were analyzed.
Modeling coupled nitrogen and water use strategies of plant productivity through hydraulic traits
Mackay, D. S.; Savoy, P.; Pleban, J. R.; Tai, X.; Ewers, B. E.; Sperry, J.; Weinig, C.
2016-12-01
Changes in heat, nutrient, and drought stresses create novel environments that threaten the health of forests and viability of crop production. Here a trait-based conceptual model finds tradeoffs in maximum hydraulic conductance (Kmax), root to leaf area ratio (RLA) and vulnerability to cavitation (VC) based on the energy costs of acquiring water and nitrogen (N) to support gross primary production (GPP). The atmosphere supplies carbon to and demands water from plants via their stomata. The demand for water increases at higher temperatures due to increased vapor pressure deficits. The lost water is replenished by a passive wicking process that pulls water and N from the soil into roots and up water-filled xylem tubes. When water is in short supply the cost of getting it is high as measured by a decline in K and stomatal closure. Soil N dynamics also influence plant water use. When N is abundant, plants grow low VC fine roots with lower specific root length (m g-1), low Kmax, and maintain a relatively low RLA. In low N environments, N is costly and fine roots gain efficiency by building less robust (or higher VC) xylem with higher Kmax and higher RLA. What happens when the cost of acquiring water changes from high to low under low and high N costs? We incorporated the conceptual model into TREES, which couples whole plant hydraulics to carbon allocation, root-rhizosphere expansion/contraction and, also new for this study, a rhizosphere-root centric microbe-plant N dynamics. We used two experimental studies (drought, N) and two drought-prone fluxnet sites to test the conceptual model at individual plant and regional scales, respectively, and with frequent short versus infrequent long dry periods. When water was not limiting the hydraulic tradeoffs suppressed differences in GPP between the N use strategies. When water was in short supply, however, low RLA&VC plants dropped GPP early during drought because of low Kmax. Since these plants had low VC roots they also
李勇汇; 冉兵; 朱海昱
2012-01-01
The maximum efficiency control scheme for a solid oxide fuel cell (SOFC) distributed generator (DG) in the grid-connected condition was proposed. By introducing the steady-state equations which govern the complex electrochemistry, thennodynamic and electrical processes of the SOFC DG, the relationship between the AC and DC sides of the SOFC DG was established. Analyses indicate that the control variables of the power conditioning unit are dependant of the control variables of the cell stack if the constant unity power factor operating scheme for the SOFC DG is chosen. However, the operating states of the SOFC DG under this control scheme must be subjected to the operating constraints denoted as feasible operating space (FOS). The non-linear programming method was then used to determine the maximum efficiency and the optimal control variables. Simulation results show that the SOFC DG under the maximum efficiency should maintain three DC-side operating variables constant simultaneously, namely, fuel utilization factor, excess oxygen ratio and stack operating temperature.%提出了一种固体氧化物燃料电池(solid oxide fuel cell,SOFC)分布式电源(distributed generator,DG)以最大效率并网发电的控制策略.通过引入反映内部复杂电化学、热力学和电气过程的稳态方程,建立了SOFC分布式电源交、直流两侧的联系.分析表明,SOFC分布式电源在采用恒功率因素运行方式时其功率调节单元的2个控制变量取决于电池堆的2个变量.然而,这种运行方式必须满足SOFC分布式电源的运行状态限制在被定义为合理运行空间(feasible operating space,FOS)的范围内.非线性规划方法用来计算SOFC分布式电源的最大效率和最优控制变量.仿真表明,SOFC分布式电源以最大效率发电时其直流侧氢气利用系数、过量氧气比例和电池堆温度这3个运行变量必须保持恒定.
Modeling, Optimization, and Detailed Design of a Hydraulic Flywheel-Accumulator
Strohmaier, Kyle Glenn
Improving mobile energy storage technology is an important means of addressing concerns over fossil fuel scarcity and energy independence. Traditional hydraulic accumulator energy storage, though favorable in power density, durability, cost, and environmental impact, suffers from relatively low energy density and a pressure-dependent state of charge. The hydraulic flywheel-accumulator concept utilizes both the hydro-pneumatic and rotating kinetic energy domains by employing a rotating pressure vessel. This thesis provides an in-depth analysis of the hydraulic flywheel-accumulator concept and an assessment of the advantages it offers over traditional static accumulator energy storage. After specifying a practical architecture for the hydraulic flywheel-accumulator, this thesis addresses the complex fluid phenomena and control implications associated with multi-domain energy storage. To facilitate rapid selection of the hydraulic flywheel-accumulator dimensions, computationally inexpensive material stress models are developed for each component. A drive cycle simulation strategy is also developed to assess the dynamic performance of the device. The stress models and performance simulation are combined to form a toolset that facilitates computationally-efficient model-based design. The aforementioned toolset has been embedded into a multi-objective optimization algorithm that aims to minimize the mass of the hydraulic flywheel-accumulator system and to minimize the losses it incurs over the course of a drive cycle. Two optimizations have been performed - one with constraints that reflect a vehicle-scale application, and one with constraints that reflect a laboratory application. At both scales, the optimization results suggest that the hydraulic flywheel-accumulator offers at least an order of magnitude improvement over traditional static accumulator energy storage, while operating at efficiencies between 75% and 93%. A particular hydraulic flywheel-accumulator design
Design of Pumps for Water Hydraulic Systems
Klit, Peder; Olsen, Stefan; Bech, Thomas Nørgaard
1999-01-01
This paper considers the development of two pumps for water hydraulic applications. The pumps are based on two different working principles: The Vane-type pump and the Gear-type pump. Emphasis is put on the considerations that should be made to account for water as the hydraulic fluid.......KEYWORDS: water, pump, design, vane, gear....
Hydraulic fracturing with distinct element method
Pruiksma, J.P.; Bezuijen, A.
2002-01-01
In this report, hydraulic fracturing is investigated using the distinct element code PFC2D from Itasca. Special routines were written to be able to model hydraulic fracturing. These include adding fluid flow to PFC2D and updating the fluid flow domains when fractures appear. A brief description of t
Hydraulic Actuator for Ganged Control Rods
Thompson, D. C.; Robey, R. M.
1986-01-01
Hydraulic actuator moves several nuclear-reactor control rods in unison. Electromagnetic pump pushes liquid lithium against ends of control rods, forcing them out of or into nuclear reactor. Color arrows show lithium flow for reactor startup and operation. Flow reversed for shutdown. Conceived for use aboard spacecraft, actuator principle applied to terrestrial hydraulic machinery involving motion of ganged rods.
Control arrangement for the actuation of hydraulic consumers
Kussel, W.; Dettmers, M.; Weirich, W.
1988-11-09
An arrangement for controlling the actuation of hydraulic consumers, by selectively connecting the consumers to hydraulic pressure and return lines; the control arrangement comprising a respective hydraulically operated directional control valve associated with each of the hydraulic consumers, a respective electro-magnetically operated pre-control valve associated with each of the hydraulic directional control valves, and further electro-magnetically operated directional control valve means associated with the pre-control valves, each of the hydraulic consumers being connectible to the hydraulic pressure or return lines via the associated hydraulically operated directional control valve which is actuatable by a hydraulic control line leading from the output of the associated pre-control valve, wherein the inputs of the pre-control valves are connected directly to the hydraulic return line and indirectly, via the further control valve means, to the hydraulic return line or to a hydraulic control pressure line.
Nanocoating for High-efficiency Industrial Hydraulic and Tooling Systems
Cook, Bruce [Ames Lab., Ames, IA (United States)
2011-06-22
Characterization of the AlMgB14-based coatings revealed their semi-crystalline nature; as a single phase, AlMgB_{14} appears amorphous. Combining this material with TiB2 through comminution of very fine-scale powders (~100 nm), produces a bulk solid that exceeds the hardness of its respective constituent phases. Through physical vapor deposition processing, the resulting nanocomposite coating combines the wear resistance characteristic of hard materials (e.g. the AlMgB_{14}) with a regenerating lubricant. Within the top layers (10-20 nm) of the nanocomposite coating, the same TiB2 phase used to enhance the strength and provide ductility to the otherwise brittle AlMgB_{14} material reacts with available oxygen to form boron oxide. As the atoms of TiB_{2} continue to react, layers of boric acid begin to form at the surface. This affords an exceptionally low coefficient of friction (as low as 0.02) to the coating. Physical vapor deposition processing parameters were evaluated and optimized during the project to minimize the difficulties common to transitioning a laboratory-scale process or technology to a salable product. Coating process times and temperatures, process gas flows and ramp rates, and a number of other adjustable parameters were optimized based on the results of testing and coating characterization. The overriding goal of all of these efforts was a repeatable coating process that yields the benefits observed in the laboratory, independent of the intended product or market.
Energy Efficiency Comparison between Hydraulic Hybrid and Hybrid Electric Vehicles
Jia-Shiun Chen
2015-01-01
Conventional vehicles tend to consume considerable amounts of fuel, which generates exhaust gases and environmental pollution during intermittent driving cycles. Therefore, prospective vehicle designs favor improved exhaust emissions and energy consumption without compromising vehicle performance. Although pure electric vehicles feature high performance and low pollution characteristics, their limitations are their short driving range and high battery costs. Hybrid electric vehicles (HEVs) ar...
Modeling Vertical Flow Treatment Wetland Hydraulics to Optimize Treatment Efficiency
2011-03-24
Shelley (Member) Date //signed// 10 Mar 2011 Robert Ritzi (Member) Wright State University Date iv AFIT/GES/ENV/11-M03...members; Dr. Michael Shelley, for his invaluable insights into past research of the treatment wetland at Wright Patterson AFB; and Dr. Robert Ritzi, for...Amon, J.P., A. Agrawal, M.L. Shelley, B.C. Opperman, M.P. Enright , N.D. Clemmer, T. Slusser, J. Lach, T. Sobolewski, W. Gruner, and A.C. Entingh
Maximum power operation of interacting molecular motors
Golubeva, Natalia; Imparato, Alberto
2013-01-01
We study the mechanical and thermodynamic properties of different traffic models for kinesin which are relevant in biological and experimental contexts. We find that motor-motor interactions play a fundamental role by enhancing the thermodynamic efficiency at maximum power of the motors......, as compared to the non-interacting system, in a wide range of biologically compatible scenarios. We furthermore consider the case where the motor-motor interaction directly affects the internal chemical cycle and investigate the effect on the system dynamics and thermodynamics....
CORA: Emission Line Fitting with Maximum Likelihood
Ness, Jan-Uwe; Wichmann, Rainer
2011-12-01
CORA analyzes emission line spectra with low count numbers and fits them to a line using the maximum likelihood technique. CORA uses a rigorous application of Poisson statistics. From the assumption of Poissonian noise, the software derives the probability for a model of the emission line spectrum to represent the measured spectrum. The likelihood function is used as a criterion for optimizing the parameters of the theoretical spectrum and a fixed point equation is derived allowing an efficient way to obtain line fluxes. CORA has been applied to an X-ray spectrum with the Low Energy Transmission Grating Spectrometer (LETGS) on board the Chandra observatory.
Gravity-Driven Hydraulic Fractures
Germanovich, L. N.; Garagash, D.; Murdoch, L. C.; Robinowitz, M.
2014-12-01
This study is motived by a new method for disposing of nuclear waste by injecting it as a dense slurry into a hydraulic fracture that grows downward to great enough depth to permanently isolate the waste. Disposing of nuclear waste using gravity-driven hydraulic fractures is mechanically similar to the upward growth of dikes filled with low density magma. A fundamental question in both applications is how the injected fluid controls the propagation dynamics and fracture geometry (depth and breadth) in three dimensions. Analog experiments in gelatin [e.g., Heimpel and Olson, 1994; Taisne and Tait, 2009] show that fracture breadth (the short horizontal dimension) remains nearly stationary when the process in the fracture "head" (where breadth is controlled) is dominated by solid toughness, whereas viscous fluid dissipation is dominant in the fracture tail. We model propagation of the resulting gravity-driven (buoyant or sinking), finger-like fracture of stationary breadth with slowly varying opening along the crack length. The elastic response to fluid loading in a horizontal cross-section is local and can be treated similar to the classical Perkins-Kern-Nordgren (PKN) model of hydraulic fracturing. The propagation condition for a finger-like crack is based on balancing the global energy release rate due to a unit crack extension with the rock fracture toughness. It allows us to relate the net fluid pressure at the tip to the fracture breadth and rock toughness. Unlike the PKN fracture, where breadth is known a priori, the final breadth of a finger-like fracture is a result of processes in the fracture head. Because the head is much more open than the tail, viscous pressure drop in the head can be neglected leading to a 3D analog of Weertman's hydrostatic pulse. This requires relaxing the local elasticity assumption of the PKN model in the fracture head. As a result, we resolve the breadth, and then match the viscosity-dominated tail with the 3-D, toughness
Scaling hydraulic properties of a macroporous soil
Mohanty, Binayak P.
1999-06-01
Macroporous soils exhibit significant differences in their hydraulic properties for different pore domains. Multimodal hydraulic functions may be used to describe the characteristics of multiporosity media. I investigated the usefulness of scaling to describe the spatial variability of hydraulic conductivity (K(-h)) functions of a macroporous soil in Las Nutrias, New Mexico. Piecewise-continuous hydraulic conductivity functions suitable for macroporous soils in conjunction with a hybrid similar media-functional normalization scaling approach were used. Results showed that gravity-dominated flow and the related hydraulic conductivity (K(minus;h) functions of the macropore region are more readily scalable than capillary-dominated flow properties of the mesopore and micropore regions. A possible reason for this behavior is that gravity-dominated flow in the larger pores is mostly influenced by the pore diameter which remains more uniform as compared to tortuous mesopores and micropores with variable neck and body sizes along the pore length.
Hydraulic conductivity of GCLs in MSW landfills
LI Guo-cheng; YANG Wu-chao; DAN Tang-hui
2008-01-01
The state of the art of the study on the hydraulic conductivity of GCLs is presented in terms of the in-fluence of the effective stress, chemical interactions, freeze - thaw cycles and temperature gradients. The chan-ges of void ratio caused by changes of effective stress have a direct linear effect on the hydraulic conductivity, regardless of the cation concentration or the thickness of the adsorbed layer. The hydraulic conductivity is relat-ed to the relative abundance of monovalent and divalent cation(RMD), and RMD has a great effect on the hy-draulic conductivity in weak solution. The long-term susceptibility of GCLs to increased hydraulic conductivity as a response to repeated freeze-thaw cycling is minimal, which has been proved after 150 freeze-thaw cycles. The potential of desiccation cracking increases with the increasing temperature gradient and is related to the ini-tial subsoil water content, the applied overburden stress, etc.
Modeling and Simulation of Hydraulic Engine Mounts
DUAN Shanzhong; Marshall McNea
2012-01-01
Hydraulic engine mounts are widely used in automotive powertrains for vibration isolation.A lumped mechanical parameter model is a traditional approach to model and simulate such mounts.This paper presents a dynamical model of a passive hydraulic engine mount with a double-chamber,an inertia track,a decoupler,and a plunger.The model is developed based on analogy between electrical systems and mechanical-hydraulic systems.The model is established to capture both low and high frequency dynatmic behaviors of the hydraulic mount.The model will be further used to find the approximate pulse responses of the mounts in terms of the force transmission and top chamber pressure.The close form solution from the simplifiod linear model may provide some insight into the highly nonlinear behavior of the mounts.Based on the model,computer simulation has been carried out to study dynamic performance of the hydraulic mount.
An Optimisation Approach Applied to Design the Hydraulic Power Supply for a Forklift Truck
Pedersen, Henrik Clemmensen; Andersen, Torben Ole; Hansen, Michael Rygaard
2004-01-01
This paper describes the first part of a method that may be used in the design of the most energy efficient hydraulic opencircuit systems, when also considering the operational aspects of the system given in the design specifications. The method builds on a numerically based multi-level optimisat......This paper describes the first part of a method that may be used in the design of the most energy efficient hydraulic opencircuit systems, when also considering the operational aspects of the system given in the design specifications. The method builds on a numerically based multi...
GAS AND OIL POWER DISTRIBUTION RATIO OF A NEW HYDRAULIC BREAKER
ZHAO Hongqiang; LI Meixiang; GAO Bin; HE Qinghua
2007-01-01
The working principle of a new hydraulic breaker operated jointly by gas and hydraulic flow which has a reasonable structure, high efficiency and long piston life-span, is analyzed, and the optimal power distribution ratio of the sealed nitrogen gas to the high-pressure oil in the process of piston impacting is studied. Through theoretical analysis, optimization simulation and detailed calculation, it is determined that the impact system has optimal mechanical performance and highest efficiency when the distribution ratio Φis between 0.3 and 0.5. The theoretical result is also verified by repeated tests.
惠记庄; 张广辉; 聂春鹏; 刘琼
2015-01-01
The signal processing and hydraulic system of original test bench was improved,and the traction test of YJH315 sheet-metal hydraulic torque converter was carried out.Based on the numerical calculation method of three dimensional flow field,the angular momentum equation, torque equation and the calculation method of performance parameter of external characteristic for YJH315 sheet-metal hydraulic torque converter were put out.The efficiencies,torque coefficients and nominal torques under different rotating speed ratios were gotten by using MATLAB simulation software and measured test respectively,and simulation result and test result were compared.Analysis result shows that when rotating speed ratio is from 0 to 0.9,the maximum efficiency is 0.82 under test condition,the value is 0.82 under simulation condition,and the maximum error of efficiency is about 2%.The maximum torque coefficient is 2.41 under test condition,the value is 2.29 under simulation condition,and the maximum error of torque coefficient is about 3%.The maximum nominal torque is 28.7 N·m under test condition,the value is 27.3 N ·m under simulation condition,and the maximum error of nominal torque is about 3%.All the errors of three indexes are within the acceptable range,so the proposed calculation method of external characteristic for sheet-metal hydraulic torque converter is feasible.1 tab,22 figs,21 refs.%对原有试验台架的信号处理和液压系统进行改进，进行了 YJH315钣金型液力变矩器的牵引试验。应用三维流场数值计算方法，提出了 YJH315钣金型液力变矩器外特性的动量矩方程、力矩方程与性能参数计算方法。分别通过 MATLAB 仿真软件和实测试验得到了不同转速比下的效率、变矩系数和公称力矩，并将仿真结果与试验结果进行对比分析。分析结果表明：当转速比在0～0．9时，试验工况下的最大效率为0．82，仿真工况下的最大效率为0．79，
Hydraulic test for evaluation of hydrophone VSP
Yabuuchi, Satoshi; Koide, Kaoru [Power Reactor and Nuclear Fuel Development Corp., Toki, Gifu (Japan). Tono Geoscience Center
1997-12-01
This hydraulic test was carried out at the test site of Tono Geoscience Center, Mizunami-shi, Gifu Pref. in order to evaluate the reliability of the hydraulic conductivity estimated from hydrophone VSP experiment. From March to April 1997, we carried out measurements of pore-water pressure at five depths and permeability tests at seven depths down to G.L.-300m, within a borehole drilled in granitic rock. We compared the results of hydraulic test with hydrophone VSP experiment on condition that a single open fracture existed, and we obtained two notable results. First, for the granitic rock at which a single open fracture was found by BTV and also detected by hydrophone VSP experiment, the hydraulic conductivity was 1.54 x 10{sup -7} cm/sec, while for the same granitic rock at which another single open fracture was found by BTV but not detected by hydrophone VSP experiment, the hydraulic conductivity was less than 6 x 10{sup -10} cm/sec. Second, we converted the hydraulic conductivity of 1.54 x 10{sup -7} cm/sec which was obtained in a hydraulic test section of length 2.5 m into an equivalent value for a single open fracture of width 1 mm. The converted value (3.8 x 10{sup -4} cm/sec) was similar to the hydraulic conductivity estimated from hydrophone VSP experiment. In conclusion, the hydraulic test result shows that hydrophone VSP is useful to estimate an approximate hydraulic conductivity of a single open fracture. (author)
DLC coatings for hydraulic applications
Luca NOBILI; Luca MAGAGNIN
2009-01-01
Replacement of lubricating oils with water or low-viscosity fluids is highly desirable in many industrial fields, on account of the environmental and economical advantages. Low lubricity of water might be insufficient for proper operation of hydraulic components, and diamond-like carbon(DLC) coatings are very attractive as solid lubricant films. A remote-plasma PACVD process was utilized to deposit hydrogenated DLC coatings (a-C:H) on different substrates. Microindentation measurements show that the coating hardness is around 35 GPa. Tribological behavior was evaluated by block-on-ring tests performed in water and water with alumina. The wear rate was calculated after measuring the wear volume by a laser profilemeter. Morphological and compositional analysis of the wear tracks reveal that coating failure may occur by abrasive wear or delamination, depending on the substrate properties. Hard and smooth substrates give the best results and dispersed alumina particles increase the wear rate.
Aircraft Hydraulic Systems Dynamic Analysis
1978-10-01
4400 PSIG OUTLET PRESSURE ~’f UM5 S1 l .( FIF ~0RV lR 1 .I. AP (c R (V) IFWM) APPROX C ASE !VPý :iI S ReUN N•;MRF.. r p kN i t, isI A! f IN, I:E • ’l...and 1F.GI pump modelo were assumed from data supplied by CECO. 165 _ -- --- - SECTION V HYDRAULIC MOTOR MODEL DEVELOPMENT AND VERIFICATION A fixed...3 70 P.,0 601 ~4 M24.0 3 1p ’, 4 r I 1 1 ISIS 2411 APPENDIX E (CONT.) HSFR TECHNICAL MANUAL (AFAPL-TR-76-43, VOL. IV) 4.15 VANE PU`MP SUBROUTINE 4.15A
Quantum-dot Carnot engine at maximum power.
Esposito, Massimiliano; Kawai, Ryoichi; Lindenberg, Katja; Van den Broeck, Christian
2010-04-01
We evaluate the efficiency at maximum power of a quantum-dot Carnot heat engine. The universal values of the coefficients at the linear and quadratic order in the temperature gradient are reproduced. Curzon-Ahlborn efficiency is recovered in the limit of weak dissipation.
Maximum Spectral Luminous Efficacy of White Light
Murphy, T W
2013-01-01
As lighting efficiency improves, it is useful to understand the theoretical limits to luminous efficacy for light that we perceive as white. Independent of the efficiency with which photons are generated, there exists a spectrally-imposed limit to the luminous efficacy of any source of photons. We find that, depending on the acceptable bandpass and---to a lesser extent---the color temperature of the light, the ideal white light source achieves a spectral luminous efficacy of 250--370 lm/W. This is consistent with previous calculations, but here we explore the maximum luminous efficacy as a function of photopic sensitivity threshold, color temperature, and color rendering index; deriving peak performance as a function of all three parameters. We also present example experimental spectra from a variety of light sources, quantifying the intrinsic efficacy of their spectral distributions.
Hydraulic design of a low-specific speed Francis runner for a hydraulic cooling tower
Ruan, H.; Luo, X. Q.; Liao, W. L.; Zhao, Y. P.
2012-11-01
The air blower in a cooling tower is normally driven by an electromotor, and the electric energy consumed by the electromotor is tremendous. The remaining energy at the outlet of the cooling cycle is considerable. This energy can be utilized to drive a hydraulic turbine and consequently to rotate the air blower. The purpose of this project is to recycle energy, lower energy consumption and reduce pollutant discharge. Firstly, a two-order polynomial is proposed to describe the blade setting angle distribution law along the meridional streamline in the streamline equation. The runner is designed by the point-to-point integration method with a specific blade setting angle distribution. Three different ultra-low-specificspeed Francis runners with different wrap angles are obtained in this method. Secondly, based on CFD numerical simulations, the effects of blade setting angle distribution on pressure coefficient distribution and relative efficiency have been analyzed. Finally, blade angles of inlet and outlet and control coefficients of blade setting angle distribution law are optimal variables, efficiency and minimum pressure are objective functions, adopting NSGA-II algorithm, a multi-objective optimization for ultra-low-specific speed Francis runner is carried out. The obtained results show that the optimal runner has higher efficiency and better cavitation performance.
Greenslade, Thomas B., Jr.
1985-01-01
Discusses a series of experiments performed by Thomas Hope in 1805 which show the temperature at which water has its maximum density. Early data cast into a modern form as well as guidelines and recent data collected from the author provide background for duplicating Hope's experiments in the classroom. (JN)
Abolishing the maximum tension principle
Dabrowski, Mariusz P
2015-01-01
We find the series of example theories for which the relativistic limit of maximum tension $F_{max} = c^2/4G$ represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models.
Abolishing the maximum tension principle
Mariusz P. Da̧browski
2015-09-01
Full Text Available We find the series of example theories for which the relativistic limit of maximum tension Fmax=c4/4G represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models.
Hydraulic fracturing in granite under geothermal conditions
Solberg, P.; Lockner, D.; Byerlee, J.D.
1980-01-01
The experimental hydraulic fracturing of granite under geothermal conditions produces tensile fracture at rapid fluid injection rates and shear fracture at slow injection rates and elevated differential stress levels. A sudden burst of acoustic emission activity accompanies tensile fracture formation whereas the acoustic emission rate increases exponentially prior to shear fracture. Temperature does not significantly affect the failure mechanism, and the experimental results have not demonstrated the occurrence of thermal fracturing. A critical result of these experiments is that fluid injection at intermediate rates and elevated differential stress levels increases permeability by more than an order of magnitude without producing macroscopic fractures, and low-level acoustic emission activity occurs simultaneously near the borehole and propagates outward into the specimen with time. Permeability measurements conducted at atmospheric pressure both before and after these experiments show that increased permeability is produced by permanent structural changes in the rock. Although results of this study have not demonstrated the occurrence of thermal fracturing, they suggest that fluid injection at certain rates in situ may markedly increase local permeability. This could prove critical to increasing the efficiency of heat exchange for geothermal energy extraction from hot dry rock. ?? 1980.
Acworth, R. Ian; Rau, Gabriel C.; Halloran, Landon J. S.; Timms, Wendy A.
2017-04-01
Accurate determination of groundwater state of confinement and compressible storage properties at vertical resolution over depth is notoriously difficult. We use the hydraulic head response to atmospheric tides at 2 cpd frequency as a tracer to quantify barometric efficiency (BE) and specific storage (Ss) over depth. Records of synthesized Earth tides, atmospheric pressure, and hydraulic heads measured in nine piezometers completed at depths between 5 and 55 m into unconsolidated smectitic clay and silt, sand and gravel were examined in the frequency domain. The barometric efficiency increased over depth from ˜0.05 in silty clay to ˜0.15 in sands and gravels. BE for silty clay was confirmed by calculating the loading efficiency as 0.95 using rainfall at the surface. Specific storage was calculated using effective rather than total moisture. The differences in phase between atmospheric pressure and hydraulic heads at 2 cpd were ˜180° below 10 m indicating confined conditions despite the low BE. Heads in the sediment above a fine sand and silt layer at 12 m exhibited a time variable phase difference between 0° and 180° indicating varying confinement. Our results illustrate that the atmospheric tide at 2 cpd is a powerful natural tracer for quantifying groundwater state of confinement and compressible storage properties in layered formations from hydraulic heads and atmospheric pressure records without the need for externally induced hydraulic stress. This approach could significantly improve the development of conceptual hydrogeological model used for groundwater resource development and management.
Hydraulic resistance of carper of cylindrical shape mineral wool
Zhukov Aleksey Dmitrievich
2015-04-01
Full Text Available The properties of the mineral wool mat are determined by the mode of heat treatment and properties of the products. The main parameter to assess the properties of highly porous fibrous material is its resistance to the air flow, which can be estimated by the value of the hydraulic resistance. This parameter includes both the characteristics of the mineral fiber (diameter, length, density characteristics of the system as a whole (total porosity, average density, the content of fibrous inclusions and gas environment parameters (temperature and speed of its motion through the porous layer. Characteristics of the gaseous medium are technological factors, which influence the material during the heat treatment, and hence optimization of the process parameters. The flow of gas through the perforated wall of the hole determined by characteristics, pressurized inside a rolling pin, and the structural characteristics of the mineral geometrical cylinder and his hydraulic resistance. So, a universal criterion, which measures the mass transfer efficiency and hence the effectiveness of the heat treatment, is a hydraulic resistance cylinder. The study of the processes occurring in the mineral wool carpet, showed that its hydraulic resistance is directly proportional to the surface of fibers per unit bed volume and inversely proportional to the third degree of porosity of the layer. Researches have shown that increasing the degree of perforation increases the uneven distribution. However, if total power increases 1.87 times, because the perforation through the inlet portion perforation of rolling pin was disclosure, substantially uniform distribution was achieved. The investigations led to the following conclusions: the specific surface layer has a linear dependence on its average density; hydraulic resistance of the layer will be greater, when the amount of beads and fibers diameter is smaller. The obtained exact dependence allows calculating the hydraulic
Assessing soil hydraulic characteristics using HYPROP and BEST: a comparison
Leitinger, Georg; Obojes, Nikolaus; Lassabatère, Laurent
2015-04-01
Knowledge of ecohydrological characteristics with high spatial resolution is a prerequisite for large-scale hydrological modelling. Data on soil hydraulic characteristics are of major importance, but measurements are often seen as time consuming and costly. In order to accurately model grassland productivity and in particular evapotranspiration, soil sampling and infiltration experiments at 25 grassland sites ranging from 900m to 2300m a.s.l. were conducted in the long term socio-ecological research (LTSER) site Stubai Valley, Tyrolean Alps, Austria, covering 265 km². Here we present a comparison of two methods to determine important hydrological properties of soils: (1) the evaporation method HYPROP (Hydraulic Property Analyzer; UMS Munich, 2010), and (2) the BEST-model (Beerkan Estimation of Soil Transfer Parameters; Lassabatère et al. (2006)), each determining the soil hydraulic characteristics and in particular the water retention curve. For the most abundant soil types we compared the pf-curves calculated from HYPROP data suing the Van Genuchten equation to the ones resulting from the comparatively time efficient BEST approach to find out if the latter is a suitable method to determine pf curves of alpine grassland soils. Except for the soil type Rendzina, the comparison of HYPROP and BEST showed slightly variations in the pF curves and resulting hydraulic characteristics. At the starting point BEST curves presented a slower dehydration, HYPROP a fast and continuous water loss. HYPROP analyses showed the highest variability in the measured values of Rendzina. Regarding BEST, the Alluvial Soils showed the highest variability. To assess equivalence between HYPROP and BEST we deduced several hydraulic characteristics from the pF curves, e.g. saturated water content, field capacity, permanent wilting point, pore size distribution, and minimum water retention. The comparison of HYPROP and BEST revealed that the results of soil water characteristics may depend on
Tellez, Jackson; Gomez, Manuel; Russo, Beniamino; Redondo, Jose M.
2015-04-01
An important achievement in hydraulic engineering is the proposal and development of new techniques for the measurement of field velocities in hydraulic problems. The technological advances in digital cameras with high resolution and high speed found in the market, and the advances in digital image processing techniques now provides a tremendous potential to measure and study the behavior of the water surface flows. This technique was applied at the Laboratory of Hydraulics at the Technical University of Catalonia - Barcelona Tech to study the 2D velocity fields in the vicinity of a grate inlet. We used a platform to test grate inlets capacity with dimensions of 5.5 m long and 4 m wide allowing a zone of useful study of 5.5m x 3m, where the width is similar of the urban road lane. The platform allows you to modify the longitudinal slopes from 0% to 10% and transversal slope from 0% to 4%. Flow rates can arrive to 200 l/s. In addition a high resolution camera with 1280 x 1024 pixels resolution with maximum speed of 488 frames per second was used. A novel technique using particle image velocimetry to measure surface flow velocities has been developed and validated with the experimental data from the grate inlets capacity. In this case, the proposed methodology can become a useful tools to understand the velocity fields of the flow approaching the inlet where the traditional measuring equipment have serious problems and limitations. References DigiFlow User Guide. (2012), (June). Russo, B., Gómez, M., & Tellez, J. (2013). Methodology to Estimate the Hydraulic Efficiency of Nontested Continuous Transverse Grates. Journal of Irrigation and Drainage Engineering, 139(10), 864-871. doi:10.1061/(ASCE)IR.1943-4774.0000625 Teresa Vila (1), Jackson Tellez (1), Jesus Maria Sanchez (2), Laura Sotillos (1), Margarita Diez (3, 1), and J., & (1), M. R. (2014). Diffusion in fractal wakes and convective thermoelectric flows. Geophysical Research Abstracts - EGU General Assembly 2014
ZHAO Binjuan; WANG Yu; CHEN Huilong; QIU Jing; HOU Duohua
2015-01-01
Computational fluid dynamics (CFD) can give a lot of potentially very useful information for hydraulic optimization design of pumps, however, it cannot directly state what kind of modification should be made to improve such hydrodynamic performance. In this paper, a more convenient and effective approach is proposed by combined using of CFD, multi-objective genetic algorithm (MOGA) and artificial neural networks (ANN) for a double-channel pump’s impeller, with maximum head and efficiency set as optimization objectives, four key geometrical parameters including inlet diameter, outlet diameter, exit width and midline wrap angle chosen as optimization parameters. Firstly, a multi-fidelity fitness assignment system in which fitness of impellers serving as tralning and comparison samples for ANN is evaluated by CFD, meanwhile fitness of impellers generated by MOGA is evaluated by ANN, is established and dramatically reduces the computational expense. Then, a modified MOGA optimization process, in which selection is performed independently in two sub-populations according to two optimization objectives, crossover and mutation is performed afterword in the merged population, is developed to ensure the global optimal solution to be found. Finally, Pareto optimal frontier is found after 500 steps of iterations, and two optimal design schemes are chosen according to the design requirements. The preliminary and optimal design schemes are compared, and the comparing results show that hydraulic performances of both pumps 1 and 2 are improved, with the head and efficiency of pump 1 increased by 5.7% and 5.2%, respectively in the design working conditions, meanwhile shaft power decreased in all working conditions, the head and efficiency of pump 2 increased by 11.7% and 5.9%, respectively while shaft power increased by 5.5%. Inner flow field analyses also show that the backflow phenomenon significantly diminishes at the entrance of the optimal impellers 1 and 2, both the area
A Note on k-Limited Maximum Base
Yang Ruishun; Yang Xiaowei
2006-01-01
The problem of k-limited maximum base was specified into two special problems of k-limited maximum base; that is, let subset D of the problem of k-limited maximum base be an independent set and a circuit of the matroid, respectively. It was proved that under this circumstance the collections of k-limited base satisfy base axioms. Then a new matroid was determined, and the problem of k-limited maximum base was transformed to the problem of maximum base of this new matroid. Aiming at the problem, two algorithms, which in essence are greedy algorithms based on former matroid, were presented for the two special problems of k-limited maximum base. They were proved to be reasonable and more efficient than the algorithm presented by Ma Zhongfan in view of the complexity of algorithm.
Effects of Microneedle Design Parameters on Hydraulic Resistance
Hood, R. Lyle; Kosoglu, Mehmet A.; Parker, Matthew; Rylander, Christopher G.
2011-01-01
Microneedles have been an expanding medical technology in recent years due to their ability to penetrate tissue and deliver therapy with minimal invasiveness and patient discomfort. Variations in design have allowed for enhanced fluid delivery, biopsy collection, and the measurement of electric potentials. Our novel microneedle design attempts to combine many of these functions into a single length of silica tubing capable of both light and fluid delivery terminating in a sharp tip of less than 100 microns in diameter. This manuscript focuses on the fluid flow aspects of the design, characterizing the contributions to hydraulic resistance from the geometric parameters of the microneedles. Experiments consisted of measuring the volumetric flow rate of de-ionized water at set pressures (ranging from 69-621 kPa) through a relevant range of tubing lengths, needle lengths, and needle tip diameters. Data analysis showed that the silica tubing (~150 micron bore diameter) adhered to within ±5% of the theoretical prediction by Poiseuille’s Law describing laminar internal pipe flow at Reynolds numbers less than 700. High hydraulic resistance within the microneedles correlated with decreasing tip diameter. The hydraulic resistance offered by the silica tubing preceding the microneedle taper was approximately 1-2 orders of magnitude less per unit length, but remained the dominating resistance in most experiments as the tubing length was >30 mm. These findings will be incorporated into future design permutations to produce a microneedle capable of both efficient fluid transfer and light delivery. PMID:22211159
HYDRAULIC ELEVATOR INSTALLATION ESTIMATION FOR THE WATER SOURCE WELL SAND-PACK CLEANING UP
V. V. Ivashechkin
2016-01-01
Full Text Available The article offers design of a hydraulic elevator installation for cleaning up water-source wells of sand packs. It considerers the installation hydraulic circuit according to which the normal pump feeds the high-level tank water into the borehole through two parallel water lines. The water-jet line with washing nozzle for destroying the sand-pack and the supply pipe-line coupled with the operational nozzle of the hydraulic elevator containing the inlet and the supply pipelines for respectively intaking the hydromixture and removing it from the well. The paper adduces equations for fluid motion in the supply and the water-jet pipelines and offers expressions for evaluating the required heads in them. For determining water flow in the supply and the water-jet pipe lines the author proposes to employ graphical approach allowing finding the regime point in Q–H chart by means of building characteristics of the pump and the pipe-lines. For calculating the useful vertical head, supply and dimensions of the hydraulic elevator the article employs the equation of motion quantity with consistency admission of the motion quantity before and after mixing the flows in the hydraulic elevator. The suggested correlations for evaluating the hydraulic elevator efficiency determine the sand pack removal duration as function of its sizes and the ejected fluid flow rate. A hydraulic-elevator installation parameters estimation example illustrates removing a sand pack from a water-source borehole of 41 m deep and 150 mm diameter bored in the village of Uzla of Myadelsk region, of Minsk oblast. The working efficiency of a manufactured and laboratory tested engineering prototype of the hydraulic elevator installation was acknowledged in actual tests at the indicated borehole site. With application of graphical approach, the suggested for the hydraulic elevator installation parameters calculation procedure allows selecting, with given depth and the borehole diameter
Layered clustering multi-fault diagnosis for hydraulic piston pump
Du, Jun; Wang, Shaoping; Zhang, Haiyan
2013-04-01
Efficient diagnosis is very important for improving reliability and performance of aircraft hydraulic piston pump, and it is one of the key technologies in prognostic and health management system. In practice, due to harsh working environment and heavy working loads, multiple faults of an aircraft hydraulic pump may occur simultaneously after long time operations. However, most existing diagnosis methods can only distinguish pump faults that occur individually. Therefore, new method needs to be developed to realize effective diagnosis of simultaneous multiple faults on aircraft hydraulic pump. In this paper, a new method based on the layered clustering algorithm is proposed to diagnose multiple faults of an aircraft hydraulic pump that occur simultaneously. The intensive failure mechanism analyses of the five main types of faults are carried out, and based on these analyses the optimal combination and layout of diagnostic sensors is attained. The three layered diagnosis reasoning engine is designed according to the faults' risk priority number and the characteristics of different fault feature extraction methods. The most serious failures are first distinguished with the individual signal processing. To the desultory faults, i.e., swash plate eccentricity and incremental clearance increases between piston and slipper, the clustering diagnosis algorithm based on the statistical average relative power difference (ARPD) is proposed. By effectively enhancing the fault features of these two faults, the ARPDs calculated from vibration signals are employed to complete the hypothesis testing. The ARPDs of the different faults follow different probability distributions. Compared with the classical fast Fourier transform-based spectrum diagnosis method, the experimental results demonstrate that the proposed algorithm can diagnose the multiple faults, which occur synchronously, with higher precision and reliability.
Aerobic biodegradation of organic compounds in hydraulic fracturing fluids.
Kekacs, Daniel; Drollette, Brian D; Brooker, Michael; Plata, Desiree L; Mouser, Paula J
2015-07-01
Little is known of the attenuation of chemical mixtures created for hydraulic fracturing within the natural environment. A synthetic hydraulic fracturing fluid was developed from disclosed industry formulas and produced for laboratory experiments using commercial additives in use by Marcellus shale field crews. The experiments employed an internationally accepted standard method (OECD 301A) to evaluate aerobic biodegradation potential of the fluid mixture by monitoring the removal of dissolved organic carbon (DOC) from an aqueous solution by activated sludge and lake water microbial consortia for two substrate concentrations and four salinities. Microbial degradation removed from 57 % to more than 90 % of added DOC within 6.5 days, with higher removal efficiency at more dilute concentrations and little difference in overall removal extent between sludge and lake microbe treatments. The alcohols isopropanol and octanol were degraded to levels below detection limits while the solvent acetone accumulated in biological treatments through time. Salinity concentrations of 40 g/L or more completely inhibited degradation during the first 6.5 days of incubation with the synthetic hydraulic fracturing fluid even though communities were pre-acclimated to salt. Initially diverse microbial communities became dominated by 16S rRNA sequences affiliated with Pseudomonas and other Pseudomonadaceae after incubation with the synthetic fracturing fluid, taxa which may be involved in acetone production. These data expand our understanding of constraints on the biodegradation potential of organic compounds in hydraulic fracturing fluids under aerobic conditions in the event that they are accidentally released to surface waters and shallow soils.
Maximum Genus of Strong Embeddings
Er-ling Wei; Yan-pei Liu; Han Ren
2003-01-01
The strong embedding conjecture states that any 2-connected graph has a strong embedding on some surface. It implies the circuit double cover conjecture: Any 2-connected graph has a circuit double cover.Conversely, it is not true. But for a 3-regular graph, the two conjectures are equivalent. In this paper, a characterization of graphs having a strong embedding with exactly 3 faces, which is the strong embedding of maximum genus, is given. In addition, some graphs with the property are provided. More generally, an upper bound of the maximum genus of strong embeddings of a graph is presented too. Lastly, it is shown that the interpolation theorem is true to planar Halin graph.
Influence of hydraulic retention time on the psychrophilic hydrolysis/acidogenesis of proteins.
Poirrier, Paola; Schiappacasse, María Cristina; Carballa, Marta; Lema, Juan M
2016-11-01
The influence of the hydraulic retention time (HRT) on the anaerobic hydrolysis of complex substrates has been studied under psychrophilic conditions. For this purpose, a continuous stirred tank reactor was operated at 15 °C and neutral pH and gelatin was considered as a model protein. Three HRTs have been tested: 12, 21 and 36 h. Gelatin hydrolysis was greatly dependent on HRT, increasing from 40% at 12 h-HRT to a maximum of 65% at 36 h-HRT. Molecular size distribution analyses of the effluent showed that hydrolysation of compounds larger than 10 kDa was poor at 12 h-HRT, whereas the fraction of 1-10 kDa was completely transformed into compounds smaller than 1 kDa. Higher HRT (36 h) improved the degradation of the recalcitrant fraction (>10 kDa), obtaining an effluent with around 95% of soluble molecules (<1 kDa). In that way, the use of membrane bioreactors for the treatment of this type of macromolecules could improve the degradation efficiencies by enabling to increase the residence time of the non-hydrolyzed molecules, with what would be possible to achieve higher organic loading rate operation.
Numerical analysis on the cavitation and unsteady flow in a scroll hydraulic pump
Sun, S. H.; Guo, P. C.; Huang, Y.; Zuo, J. L.; Luo, X. Q.
2016-05-01
This paper presents numerical analysis of unsteady flow in a scroll hydraulic pump to discover its flow mechanism. The dynamic mesh model has to be used to simulate the flow field unsteadily. The unsteady flow patterns and pressure distributions in the suction, squeezing and discharge chamber are analysed. The suction process continues until the crank angle reaches the 320 degree. Then the pressure in the chamber rises instantaneously, and the fluid begins to flow out from the chamber. Because of the high pressure difference at the clearance, the jet flow and the vortex appear, and the large flow losses generates with them. In addition, the velocity and static pressure distribution in the two symmetry crescent suction chamber is different remarkably. One reason is that the location of suction port cannot be set symmetrically for the simplification of the pump structure. Another reason for that is the fluid is impelled by different part of the orbiting scroll. The asymmetric pressure distribution will result in the extra force on the scroll. The cavitation generates at the negative pressure region. Therefore, the unsteady simulation shows some important phenomena. The structure of the scroll pump need to be optimized to reduce the maximum pressure, weaken the jet flow, vortex and the uneven pressure distribution to ensure the pump working safely and efficiently.
Pinheiro, Larissa Cunha; Su, Jian, E-mail: larissa@lasme.coppe.ufrj.br, E-mail: sujian@lasme.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Programa de Engenhraria Nuclear; Cotta, Renato Machado, E-mail: cotta@mecanica.coppe.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (POLI/COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Dept. de Engenharia Mecanica
2015-07-01
Single phase natural circulation circuits composed of two convective heat exchangers and connecting tubes are important for the passive heat removal from spent fuel pools (SFP). To keep the structural integrity of the stored spent fuel assemblies, continuously cooling has to be provided in order to avoid increase at the pool temperature and subsequent uncovering of the fuel and enhanced reaction between water and metal releasing hydrogen. Decay heat can achieve considerably high amounts of energy e.g. in the AP1000, considering the emergency fuel assemblies, the maximum heat decay will reach 13 MW in the 15th day (Westinghouse Electric Company, 2010). A highly efficient alternative to do so is by means of natural circulation, which is cost-effective compared to active cooling systems and is inherently safer since presents less associated devices and no external work is required. Many researchers have investigated safety and stability aspects of natural circulation loops (NCL). However, there is a lack of literature concerning the improvement of NCL through a standard unified methodology, especially for natural circulation circuits with two heat exchangers. In the present study, a simplified thermal-hydraulic analysis of single phase natural circulation circuit with two heat exchanges is presented. Relevant dimensionless key groups were proposed to for the design and safety analysis of a scaled NCL for the cooling of spent fuel storage pool with convective cooling and heating. (author)
Microcosm wetlands for wastewater treatment with different hydraulic loading rates and macrophytes.
Jing, Shuh-Ren; Lin, Ying-Feng; Wang, Tze-Wen; Lee, Der-Yuan
2002-01-01
Constructed wetlands (CW) usually require large land areas for treating wastewater. This study evaluated the feasibility of applying CW with less land requirement by operating a group of microcosm wetlands at a hydraulic retention time (HRT) of less than 4 d in southern Taiwan. An artificial wastewater, simulating municipal wastewater containing 200 mg L(-1) of chemical oxygen demand (COD), 20 mg L(-1) of NH4+-N (AN), and 20 mg L(-1) of PO4(3-)-P (OP), was the inflow source. Three emergent plants [reed, Phragmites australis (Cav.) Trin. ex Steud.; water primrose, Ludwigia octovalvis (Jacq.) P.H. Raven; and dayflower, Commelina communis L.] and two floating plants [water spinach, Ipomoea aquatica Forssk.; and water lettuce, Pistia stratiotes L.] plants were tested. The planted systems showed more nutrient removal than unplanted systems; however, the type of macrophytes in CW did not make a major difference in treatment. At the HRTs of 2 to 4 d, the planted system maintained greater than 72,80, and 46% removal for COD, AN, and OP, respectively. For AN and OP removal, the highest efficiencies occurred at the HRT of 3 d, whereas maximum removal rates for AN and OP occurred at the HRT of 2 d. Both removal rates and efficiencies were reduced drastically at the HRT of 1 d. Removals of COD, OP, and AN followed first-order reactions within the HRTs of 1 to 4 d. The efficient removals of these constituents obtained with HRT between 2 and 4 d indicated the possibility of using a CW system for wastewater treatment with less land requirement.
Remizov, Ivan D
2009-01-01
In this note, we represent a subdifferential of a maximum functional defined on the space of all real-valued continuous functions on a given metric compact set. For a given argument, $f$ it coincides with the set of all probability measures on the set of points maximizing $f$ on the initial compact set. This complete characterization lies in the heart of several important identities in microeconomics, such as Roy's identity, Sheppard's lemma, as well as duality theory in production and linear programming.
An inversion strategy for hydraulic tomography: Coupling travel time and amplitude inversion
Brauchler, R.; Cheng, J.-T.; Dietrich, P.; Everett, M.; Johnson, B.; Liedl, R.; Sauter, M.
2007-10-01
SummaryWe present a hydraulic tomographic inversion strategy with an emphasis on the reduction of ambiguity of hydraulic travel time inversion results and the separation of the estimated diffusivity values into hydraulic conductivity and specific storage. Our tomographic inversion strategy is tested by simulated multilevel interference slug tests in which the positions of the sources (injection ports) and the receivers (observation ports) isolated with packers are varied. Simulations include the delaying effect of wellbore storage on travel times which are quantified and shown to be of increasing importance for shorter travel distances. For the reduction of ambiguity of travel time inversion, we use the full travel time data set, as well as smaller data subsets of specified source-receiver angles. The inversion results of data subsets show different resolution characteristics and improve the reliability of the interpretation. The travel time of a pressure pulse is a function of the diffusivity of the medium between the source and receiver. Thus, it is difficult to directly derive values for hydraulic conductivity and specific storage by inverting travel times. In order to overcome this limitation, we exploit the great computational efficiency of hydraulic travel time tomography to define the aquifer structure, which is then input into the underlying groundwater flow model MODFLOW-96. Finally, we perform a model calibration (amplitude inversion) using the automatic parameter estimator PEST, enabling us to separate diffusivity into its two components hydraulic conductivity and specific storage.
The Testability of Maximum Magnitude
Clements, R.; Schorlemmer, D.; Gonzalez, A.; Zoeller, G.; Schneider, M.
2012-12-01
Recent disasters caused by earthquakes of unexpectedly large magnitude (such as Tohoku) illustrate the need for reliable assessments of the seismic hazard. Estimates of the maximum possible magnitude M at a given fault or in a particular zone are essential parameters in probabilistic seismic hazard assessment (PSHA), but their accuracy remains untested. In this study, we discuss the testability of long-term and short-term M estimates and the limitations that arise from testing such rare events. Of considerable importance is whether or not those limitations imply a lack of testability of a useful maximum magnitude estimate, and whether this should have any influence on current PSHA methodology. We use a simple extreme value theory approach to derive a probability distribution for the expected maximum magnitude in a future time interval, and we perform a sensitivity analysis on this distribution to determine if there is a reasonable avenue available for testing M estimates as they are commonly reported today: devoid of an appropriate probability distribution of their own and estimated only for infinite time (or relatively large untestable periods). Our results imply that any attempt at testing such estimates is futile, and that the distribution is highly sensitive to M estimates only under certain optimal conditions that are rarely observed in practice. In the future we suggest that PSHA modelers be brutally honest about the uncertainty of M estimates, or must find a way to decrease its influence on the estimated hazard.
Alternative Multiview Maximum Entropy Discrimination.
Chao, Guoqing; Sun, Shiliang
2016-07-01
Maximum entropy discrimination (MED) is a general framework for discriminative estimation based on maximum entropy and maximum margin principles, and can produce hard-margin support vector machines under some assumptions. Recently, the multiview version of MED multiview MED (MVMED) was proposed. In this paper, we try to explore a more natural MVMED framework by assuming two separate distributions p1( Θ1) over the first-view classifier parameter Θ1 and p2( Θ2) over the second-view classifier parameter Θ2 . We name the new MVMED framework as alternative MVMED (AMVMED), which enforces the posteriors of two view margins to be equal. The proposed AMVMED is more flexible than the existing MVMED, because compared with MVMED, which optimizes one relative entropy, AMVMED assigns one relative entropy term to each of the two views, thus incorporating a tradeoff between the two views. We give the detailed solving procedure, which can be divided into two steps. The first step is solving our optimization problem without considering the equal margin posteriors from two views, and then, in the second step, we consider the equal posteriors. Experimental results on multiple real-world data sets verify the effectiveness of the AMVMED, and comparisons with MVMED are also reported.
Design of a New Type of Distribution Valve for Hydraulic Breaker and Analysis of Energy Consumption
无
2006-01-01
Energy consumed by distribution valves causes an energy loss for the output energy of hydraulic breakers, which has a significant influence on its efficiency. A new type of distribution valve used for hydraulic breakers, designed to reduce energy consumption, is analyzed on the basis of the operating principle and energy loss of the current distribution valve. The new distribution valve adopts a cone valve and the optimization technique of unequal open degree for the valve port. Theoretical calculations and analyses have proven that the new distribution valve can reduce energy loss by 9.0127J, or energy consumption by 31%, during an impact cycle and the efficiency of the hydraulic breaker can be raised by 4.5%. It has the following characteristics: little leakage, little pressure loss and low energy consumption.
Regenerative Braking Control Strategy of Electric-Hydraulic Hybrid (EHH Vehicle
Yang Yang
2017-07-01
Full Text Available A novel electric-hydraulic hybrid drivetrain incorporating a set of hydraulic systems is proposed for application in a pure electric vehicle. Models of the electric and hydraulic components are constructed. Two control strategies, which are based on two separate rules, are developed; the maximum energy recovery rate strategy adheres to the rule of the maximization of the braking energy recovery rate, while the minimum current impact strategy adheres to the rule of the minimization of the charge current to the battery. The simulation models were established to verify the effects of these two control strategies. An ABS (Anti-lock Braking System fuzzy control strategy is also developed and simulated. The simulation results demonstrate that the developed control strategy can effectively absorb the braking energy, suppress the current impact, and assure braking safety.
Final design of a free-piston hydraulic advanced Stirling conversion system
Wallace, D. A.; Noble, J. E.; Emigh, S. G.; Ross, B. A.; Lehmann, G. A.
1991-01-01
Under the US Department of Energy's (DOEs) Solar Thermal Technology Program, Sandia National Laboratories is evaluating heat engines for solar distributed receiver systems. The final design is described of an engineering prototype advanced Stirling conversion system (ASCS) with a free-piston hydraulic engine output capable of delivering about 25 kW of electric power to a utility grid. The free-piston Stirling engine has the potential for a highly reliable engine with long life because it has only a few moving parts, has noncontacting bearings, and can be hermetically sealed. The ASCS is designed to deliver maximum power per year over a range of solar input with a design life of 30 years (60,000 h). The system includes a liquid Nak pool boiler heat transport system and a free-piston Stirling engine with high-pressure hydraulic output, coupled with a bent axis variable displacement hydraulic motor and a rotary induction generator.
A New Type of Continuously Variable Displacement Mechanism Used for Hydraulic Motors
LI Yong; SHI Guang-lin; CHEN Zhao-neng
2007-01-01
A continuously variable displacement mechanism, which is composed of a hydraulic control valve with mechanical-positional feedback to camshaft, was designed for changing the displacement of traditional camshaft connecting-rod low speed high torque (LSHT) hydraulic motor continuously. The new type of continuously variable displacement mechanism is simple and easy to be made. The structure and principle of a continuously variable displacement mechanism was introduced. The mathematic model of the continuously variable displacement mechanism was set up and its static and dynamic characteristics were analyzed with the help of computer simulation. It can be seen that the cam ring on camshaft of the traditional LSHT hydraulic motor can stop at any position between minimum and maximum eccentricity, according to an input fluid pressure signal. And it can also stay anywhere stably through self-adjusting. Besides, it can work stabilized when load impact or oil leakage exists.
DESIGN AND CONSTRUCTION OF A HYDRAULIC PISTON
Santos De La Cruz, Eulogio; Universidad Nacional Mayor de San Marcos; Rojas Lazo, Oswaldo; Universidad Nacional Mayor de San Marcos; Yenque Dedios, Julio; Universidad Nacional Mayor de San Marcos; Lavado Soto, Aurelio; Universidad Nacional Mayor de San Marcos
2014-01-01
A hydraulic system project includes the design, materials selection and construction of the hydraulic piston, hydraulic circuit and the joint with the pump and its accesories. This equiment will be driven by the force of moving fluid, whose application is in the devices of machines, tools, printing, perforation, packing and others. El proyecto de un sistema hidráulico, comprende el diseño, selección de materiales y construcción del pistón hidráulico, circuito hidráulico y el ensamble con l...
Bubble visualization in a simulated hydraulic jump
Witt, Adam; Shen, Lian
2013-01-01
This is a fluid dynamics video of two- and three-dimensional computational fluid dynamics simulations carried out at St. Anthony Falls Laboratory. A transient hydraulic jump is simulated using OpenFOAM, an open source numerical solver. A Volume of Fluid numerical method is employed with a realizable k-epsilon turbulence model. The goal of this research is to model the void fraction and bubble size in a transient hydraulic jump. This fluid dynamics video depicts the air entrainment characteristics and bubble behavior within a hydraulic jump of Froude number 4.82.
Design and Construction of a Hydraulic Ram Pump
Shuaibu Ndache MOHAMMED
2007-09-01
Full Text Available The Design and Fabrication of a Hydraulic Ram Pump (Hydram is undertaken. It is meant to lift water from a depth of 2m below the surface with no other external energy source required. Based on the design the volume flow rate in the derived pipe was 4.5238 × 10-5 m3/s (2.7 l/min, Power was 1.273 kW which results in an efficiency of 57.3%. The overall cost of fabrication of this hydram shows that the pump is relatively cheaper than the existing pumps.
Plenefisch, Thomas; Brückner, Lisa; Ceranna, Lars; Gestermann, Nicolai; Houben, Georg; Tischner, Torsten; Wegler, Ulrich; Wellbrink, Matthias; Bönnemann, Christian; Bertram, Andreas; Kirschbaum, Bernd
2016-04-01
Recently, the BGR has worked out a study on the potential environmental impact caused by hydraulic fracturing or chemical stimulations in deep geothermal reservoirs in Germany and adjacent areas. The investigations and analyses are based on existing studies and information provided by operators. The two environmental impacts being essentially considered in the report are induced seismicity and possible contamination of the groundwater reservoirs which serve for drinking water supply. Altogether, in this study, information on 30 hydraulic frac operations and 26 chemical stimulations including information from neighboring countries were compiled and analyzed. Out of the hydraulic stimulations two thirds were carried out as waterfracs and one third as fracturing with proppants. Parameters used in the study to characterize the induced seismicity are maximum magnitude, number of seismic events, size of the seismically active volume, and the relation of this volume to fault zones and the cap rock, as well as, finally, the impacts at the Earth's surface. The response of the subsurface to hydraulic fracturing is variable: There are some activities, which cause perceptible seismic events, others, where no perceptible but instrumentally detected events occurred, and moreover activities without even any instrumentally detected events. A classification of seismic hazard with respect to tectonic region, geology, or depth of the layer is still difficult, since the number of hydraulic fracturing measures in deep geothermal wells is small making a statistically sound analysis impossible. However, there are some indications, that hydraulic fracturing in granite in tectonically active regions like the Upper Rhine Graben results in comparatively stronger, perceptible seismicity compared to hydraulic fracturing in the sedimentary rocks of the North German basin. The maximum magnitudes of induced earthquakes caused by hydraulic fracturing of deep geothermal wells in Germany are
Hydraulic Fracturing and the Environment
Ayatollahy Tafti, T.; Aminzadeh, F.; Jafarpour, B.; de Barros, F.
2013-12-01
In this presentation, we highlight two key environmental concerns of hydraulic fracturing (HF), namely induced seismicity and groundwater contamination (GC). We examine the induced seismicity (IS) associated with different subsurface fluid injection and production (SFIP) operations and the key operational parameters of SFIP impacting it. In addition we review the key potential sources for possible water contamination. Both in the case of IS and GC we propose modeling and data analysis methods to quantify the risk factors to be used for monitoring and risk reduction. SFIP include presents a risk in hydraulic fracturing, waste water injection, enhanced oil recovery as well as geothermal energy operations. Although a recent report (NRC 2012) documents that HF is not responsible for most of the induced seismicities, we primarily focus on HF here. We look into vaious operational parameters such as volume and rate of water injection, the direction of the well versus the natural fracture network, the depth of the target and the local stress field and fault system, as well as other geological features. The latter would determine the potential for triggering tectonic related events by small induced seismicity events. We provide the building blocks for IS risk assessment and monitoring. The system we propose will involve adequate layers of complexity based on mapped seismic attributes as well as results from ANN and probabilistic predictive modeling workflows. This leads to a set of guidelines which further defines 'safe operating conditions' and 'safe operating zones' which will be a valuable reference for future SFIP operations. We also illustrate how HF can lead to groundwater aquifer contamination. The source of aquifer contamination can be the hydrocarbon gas or the chemicals used in the injected liquid in the formation. We explore possible pathways of contamination within and discuss the likelihood of contamination from each source. Many of the chemical compounds used
Sack, Lawren; Ball, Marilyn C; Brodersen, Craig; Davis, Stephen D; Des Marais, David L; Donovan, Lisa A; Givnish, Thomas J; Hacke, Uwe G; Huxman, Travis; Jansen, Steven; Jacobsen, Anna L; Johnson, Daniel M; Koch, George W; Maurel, Christophe; McCulloh, Katherine A; McDowell, Nate G; McElrone, Andrew; Meinzer, Frederick C; Melcher, Peter J; North, Gretchen; Pellegrini, Matteo; Pockman, William T; Pratt, R Brandon; Sala, Anna; Santiago, Louis S; Savage, Jessica A; Scoffoni, Christine; Sevanto, Sanna; Sperry, John; Tyerman, Stephen D; Way, Danielle; Holbrook, N Michele
2016-09-01
Water plays a central role in plant biology and the efficiency of water transport throughout the plant affects both photosynthetic rate and growth, an influence that scales up deterministically to the productivity of terrestrial ecosystems. Moreover, hydraulic traits mediate the ways in which plants interact with their abiotic and biotic environment. At landscape to global scale, plant hydraulic traits are important in describing the function of ecological communities and ecosystems. Plant hydraulics is increasingly recognized as a central hub within a network by which plant biology is connected to palaeobiology, agronomy, climatology, forestry, community and ecosystem ecology and earth-system science. Such grand challenges as anticipating and mitigating the impacts of climate change, and improving the security and sustainability of our food supply rely on our fundamental knowledge of how water behaves in the cells, tissues, organs, bodies and diverse communities of plants. A workshop, 'Emerging Frontiers in Plant Hydraulics' supported by the National Science Foundation, was held in Washington DC, 2015 to promote open discussion of new ideas, controversies regarding measurements and analyses, and especially, the potential for expansion of up-scaled and down-scaled inter-disciplinary research, and the strengthening of connections between plant hydraulic research, allied fields and global modelling efforts.
Ganzmann, I.; Hille, D.; Staude, U. [AREVA NP GmbH (Germany). Materials, Fluid-Structure Interaction, Plant Life Management NTCM-G
2009-07-01
The reliable fuel element behavior during the complete fuel cycle is one of the fundamental prerequisites of a safe and efficient nuclear power plant operation. The fuel element behavior with respect to pressure drop and vibration impact cannot be simulated by means of fluid-structure interaction codes. Therefore it is necessary to perform tests using fuel element mock-ups (1:1). AREVA NP has constructed the test facility PETER (PWR fuel element tests in Erlangen) loop. The modular construction allows maximum flexibility for any type of fuel elements. Modern measuring instrumentation for flow, pressure and vibration characterization allows the analysis of cause and consequences of thermal hydraulic phenomena. PETER loop is the standard test facility for the qualification of dynamic fuel element behavior in flowing fluid and is used for failure mode analysis.
Conceptual design and cost analysis of hydraulic output unit for 15 kW free-piston Stirling engine
White, M. A.
1982-01-01
A long-life hydraulic converter with unique features was conceptually designed to interface with a specified 15 kW(e) free-piston Stirling engine in a solar thermal dish application. Hydraulic fluid at 34.5 MPa (5000 psi) is produced to drive a conventional hydraulic motor and rotary alternator. Efficiency of the low-maintenance converter design was calculated at 93.5% for a counterbalanced version and 97.0% without the counterbalance feature. If the converter were coupled to a Stirling engine with design parameters more typcial of high-technology Stirling engines, counterbalanced converter efficiency could be increased to 99.6%. Dynamic computer simulation studies were conducted to evaluate performance and system sensitivities. Production costs of the complete Stirling hydraulic/electric power system were evaluated at $6506 which compared with $8746 for an alternative Stirling engine/linear alternator system.
Westhoff, M.; Erpicum, S.; Archambeau, P.; Pirotton, M.; Zehe, E.; Dewals, B.
2015-12-01
Power can be performed by a system driven by a potential difference. From a given potential difference, the power that can be subtracted is constraint by the Carnot limit, which follows from the first and second laws of thermodynamics. If the system is such that the flux producing power (with power being the flux times its driving potential difference) also influences the potential difference, a maximum in power can be obtained as a result of the trade-off between the flux and the potential difference. This is referred to as the maximum power principle. It has already been shown that the atmosphere operates close to this maximum power limit when it comes to heat transport from the Equator to the poles, or vertically, from the surface to the atmospheric boundary layer. To reach this state of maximum power, the effective thermal conductivity of the atmosphere is adapted by the creation of convection cells. The aim of this study is to test if the soil's effective hydraulic conductivity also adapts in such a way that it produces maximum power. However, the soil's hydraulic conductivity adapts differently; for example by the creation of preferential flow paths. Here, this process is simulated in a lab experiment, which focuses on preferential flow paths created by piping. In the lab, we created a hydrological analogue to the atmospheric model dealing with heat transport between Equator and poles, with the aim to test if the effective hydraulic conductivity of the sand bed can be predicted with the maximum power principle. The experimental setup consists of two freely draining reservoir connected with each other by a confined aquifer. By adding water to only one reservoir, a potential difference will build up until a steady state is reached. The results will indicate whether the maximum power principle does apply for groundwater flow and how it should be applied. Because of the different way of adaptation of flow conductivity, the results differ from that of the
Parker Hybrid Hydraulic Drivetrain Demonstration
Collett, Raymond [Parker-Hannifin Corporation, Cleveland, OH (United States); Howland, James [Parker-Hannifin Corporation, Cleveland, OH (United States); Venkiteswaran, Prasad [National Energy Technology Lab. (NETL), Morgantown, WV (United States)
2014-03-31
This report examines the benefits of Parker Hannifin hydraulic hybrid brake energy recovery systems used in commercial applications for vocational purposes. A detailed background on the problem statement being addressed as well as the solution set specific for parcel delivery will be provided. Objectives of the demonstration performed in high start & stop applications included opportunities in fuel usage reduction, emissions reduction, vehicle productivity, and vehicle maintenance. Completed findings during the demonstration period and parallel investigations with NREL, CALSTART, along with a literature review will be provided herein on this research area. Lastly, results identified in the study by third parties validated the savings potential in fuel reduction of on average of 19% to 52% over the baseline in terms of mpg (Lammert, 2014, p11), Parker data for parcel delivery vehicles in the field parallels this at a range of 35% - 50%, emissions reduction of 17.4% lower CO2 per mile and 30.4% lower NOx per mile (Gallo, 2014, p15), with maintenance improvement in the areas of brake and starter replacement, while leaving room for further study in the area of productivity in terms of specific metrics that can be applied and studied.
Thermal hydraulics development for CASL
Lowrie, Robert B [Los Alamos National Laboratory
2010-12-07
This talk will describe the technical direction of the Thermal-Hydraulics (T-H) Project within the Consortium for Advanced Simulation of Light Water Reactors (CASL) Department of Energy Innovation Hub. CASL is focused on developing a 'virtual reactor', that will simulate the physical processes that occur within a light-water reactor. These simulations will address several challenge problems, defined by laboratory, university, and industrial partners that make up CASL. CASL's T-H efforts are encompassed in two sub-projects: (1) Computational Fluid Dynamics (CFD), (2) Interface Treatment Methods (ITM). The CFD subproject will develop non-proprietary, scalable, verified and validated macroscale CFD simulation tools. These tools typically require closures for their turbulence and boiling models, which will be provided by the ITM sub-project, via experiments and microscale (such as DNS) simulation results. The near-term milestones and longer term plans of these two sub-projects will be discussed.
Transputer Control of Hydraulic Actuators and Robots
Conrad, Finn
1996-01-01
Results from a Danish mechatronics research program entitled IMCIA - Intelligent Control and Intelligent Actuators. The objective is development of intelligent actuators for intelligent motion control. A mechatronics test facility with a transputer controlled hydraulic robot suiteable for real...
Concept Evaluation for Hydraulic Yaw System
Stubkier, Søren; Pedersen, Henrik C.; Andersen, Torben Ole
2013-01-01
a suspension system on a car, leading the loads away from the turbine structure. However, to realize a soft hydraulic yaw system a new design concept must be found. As a part of the development of the new concept a preliminary concept evaluation has been conducted, evaluating seven different hydraulic yaw...... concepts, ranging from a one-to-one copy of the electrical drive (electrical drives replaced by hydraulic dittos), to floating suspension systems mounted on hydraulic cylinders. Rough calculations of size and consequences of the different systems are presented ending up with the final concept for further...... investigation. Loads and yaw demands are based on the IEC 61400-1 standard for wind turbine design, and the loads for this examination are extrapolated from the HAWC2 aeroelastic design code. The concepts are based on a 5 MW off-shore turbine....
HYDRAULICS, Des Moines COUNTY, IOWA, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydrologic procedures for estimating flood discharges for a flood insurance...
ON THE THEORIES OF HYDRAULIC GEOMETRY
Vijay P. SINGH
2003-01-01
Hydraulic geometry is of fundamental importance in planning, design, and management of river engineering and training works. Although some concepts of hydraulic geometry were proposed toward the end of the nineteenth century, the real impetus toward formulating a theory of hydraulic geometry was provided by the work of Leopold and Maddock (1953). A number of theories have since been proposed.Some of the theories are interrelated but others are based on quite different principles. All theories,however, assume that the river flow is steady and uniform and the river tends to attain a state of equilibrium or quasi-equilibrium. The differences are due to the differences in hydraulic mechanisms that the theories employ to explain the attainment of equilibrium by the river.
Stream restoration hydraulic design course: lecture notes
Newbury, R
2002-01-01
Steam restoration encompasses a broad range of activities and disciplines. This lecture series is designed for practitioners who must fit habitat improvement works in the hydraulics of degraded channels...
HYDRAULICS, Des Moines COUNTY, IOWA, USA
Federal Emergency Management Agency, Department of Homeland Security — Hydraulic data include spatial datasets and data tables necessary for documenting the hydrologic procedures for estimating flood discharges for a flood insurance...
Hydraulic fracturing chemicals and fluids technology
Fink, Johannes
2013-01-01
When classifying fracturing fluids and their additives, it is important that production, operation, and completion engineers understand which chemical should be utilized in different well environments. A user's guide to the many chemicals and chemical additives used in hydraulic fracturing operations, Hydraulic Fracturing Chemicals and Fluids Technology provides an easy-to-use manual to create fluid formulations that will meet project-specific needs while protecting the environment and the life of the well. Fink creates a concise and comprehensive reference that enables the engineer to logically select and use the appropriate chemicals on any hydraulic fracturing job. The first book devoted entirely to hydraulic fracturing chemicals, Fink eliminates the guesswork so the engineer can select the best chemicals needed on the job while providing the best protection for the well, workers and environment. Pinpoints the specific compounds used in any given fracturing operation Provides a systematic approach to class...
Transputer Control of Hydraulic Actuators and Robots
Conrad, Finn
1996-01-01
Results from a Danish mechatronics research program entitled IMCIA - Intelligent Control and Intelligent Actuators. The objective is development of intelligent actuators for intelligent motion control. A mechatronics test facility with a transputer controlled hydraulic robot suiteable for real...
Paddle River Dam : review of probable maximum flood
Clark, D. [UMA Engineering Ltd., Edmonton, AB (Canada); Neill, C.R. [Northwest Hydraulic Consultants Ltd., Edmonton, AB (Canada)
2008-07-01
The Paddle River Dam was built in northern Alberta in the mid 1980s for flood control. According to the 1999 Canadian Dam Association (CDA) guidelines, this 35 metre high, zoned earthfill dam with a spillway capacity sized to accommodate a probable maximum flood (PMF) is rated as a very high hazard. At the time of design, it was estimated to have a peak flow rate of 858 centimetres. A review of the PMF in 2002 increased the peak flow rate to 1,890 centimetres. In light of a 2007 revision of the CDA safety guidelines, the PMF was reviewed and the inflow design flood (IDF) was re-evaluated. This paper discussed the levels of uncertainty inherent in PMF determinations and some difficulties encountered with the SSARR hydrologic model and the HEC-RAS hydraulic model in unsteady mode. The paper also presented and discussed the analysis used to determine incremental damages, upon which a new IDF of 840 m{sup 3}/s was recommended. The paper discussed the PMF review, modelling methodology, hydrograph inputs, and incremental damage of floods. It was concluded that the PMF review, involving hydraulic routing through the valley bottom together with reconsideration of the previous runoff modeling provides evidence that the peak reservoir inflow could reasonably be reduced by approximately 20 per cent. 8 refs., 5 tabs., 8 figs.
46 CFR 112.50-3 - Hydraulic starting.
2010-10-01
... 46 Shipping 4 2010-10-01 2010-10-01 false Hydraulic starting. 112.50-3 Section 112.50-3 Shipping... POWER SYSTEMS Emergency Diesel and Gas Turbine Engine Driven Generator Sets § 112.50-3 Hydraulic starting. A hydraulic starting system must meet the following: (a) The hydraulic starting system must be...
21 CFR 870.2780 - Hydraulic, pneumatic, or photoelectric plethysmographs.
2010-04-01
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hydraulic, pneumatic, or photoelectric... § 870.2780 Hydraulic, pneumatic, or photoelectric plethysmographs. (a) Identification. A hydraulic... using hydraulic, pneumatic, or photoelectric measurement techniques. (b) Classification. Class...
Impact of sludge layer geometry on the hydraulic performance of a waste stabilization pond.
Ouedraogo, Faissal R; Zhang, Jie; Cornejo, Pablo K; Zhang, Qiong; Mihelcic, James R; Tejada-Martinez, Andres E
2016-08-01
Improving the hydraulic performance of waste stabilization ponds (WSPs) is an important management strategy to not only ensure protection of public health and the environment, but also to maximize the potential reuse of valuable resources found in the treated effluent. To reuse effluent from WSPs, a better understanding of the factors that impact the hydraulic performance of the system is needed. One major factor determining the hydraulic performance of a WSP is sludge accumulation, which alters the volume of the pond. In this study, computational fluid dynamics (CFD) analysis was applied to investigate the impact of sludge layer geometry on hydraulic performance of a facultative pond, typically used in many small communities throughout the developing world. Four waste stabilization pond cases with different sludge volumes and distributions were investigated. Results indicate that sludge distribution and volume have a significant impact on wastewater treatment efficiency and capacity. Although treatment capacity is reduced with accumulation of sludge, the latter may induce a baffling effect which causes the flow to behave closer to that of plug flow reactor and thus increase treatment efficiency. In addition to sludge accumulation and distribution, the impact of water surface level is also investigated through two additional cases. Findings show that an increase in water level while keeping a constant flow rate can result in a significant decrease in the hydraulic performance by reducing the sludge baffling effect, suggesting a careful monitoring of sludge accumulation and water surface level in WSP systems.
Turbulent intensity and scales of turbulence after hydraulic jump in rectangular channel
Kozioł Adam
2016-06-01
Full Text Available Turbulent intensity and scales of turbulence after hydraulic jump in rectangular channel. Experimental research was undertaken to investigate the changes in spatial turbulence intensity and scales of turbulent eddies (macroeddies in a rectangular channel and the influence of the hydraulic jump on vertical, lateral and streamwise distributions of relative turbulence intensity and scales of turbulent eddies. The results of three tests for different discharges are presented. An intensive turbulent mixing that arises as a result of a hydraulic jump has a significant effect on instantaneous velocity, turbulent intensities and sizes of eddies, as well as their vertical and longitudinal distributions. In the analysed case the most noticeable changes appeared up to 0.5 m downstream the hydraulic jump. In the vertical dimension such an effect was especially seen near the surface. The smallest streamwise sizes of macroeddies were present near the surface, maximum at the depth of z/h = 0.6 and from that point sizes were decreasing towards the bottom. The intensive turbulent mixing within the hydraulic jump generates macroeddies of small sizes.
Cacti with maximum Kirchhoff index
Wang, Wen-Rui; Pan, Xiang-Feng
2015-01-01
The concept of resistance distance was first proposed by Klein and Randi\\'c. The Kirchhoff index $Kf(G)$ of a graph $G$ is the sum of resistance distance between all pairs of vertices in $G$. A connected graph $G$ is called a cactus if each block of $G$ is either an edge or a cycle. Let $Cat(n;t)$ be the set of connected cacti possessing $n$ vertices and $t$ cycles, where $0\\leq t \\leq \\lfloor\\frac{n-1}{2}\\rfloor$. In this paper, the maximum kirchhoff index of cacti are characterized, as well...
Generic maximum likely scale selection
Pedersen, Kim Steenstrup; Loog, Marco; Markussen, Bo
2007-01-01
The fundamental problem of local scale selection is addressed by means of a novel principle, which is based on maximum likelihood estimation. The principle is generally applicable to a broad variety of image models and descriptors, and provides a generic scale estimation methodology. The focus...... on second order moments of multiple measurements outputs at a fixed location. These measurements, which reflect local image structure, consist in the cases considered here of Gaussian derivatives taken at several scales and/or having different derivative orders....
João L. Zocoler
2011-04-01
Full Text Available Neste trabalho, ajustou-se um modelo matemático para quantificar o efeito da variação do rendimento da bomba hidráulica na variação dos custos de um sistema de bombeamento, na estrutura tarifária horossazonal verde (subgrupo A4 e o tempo de recuperação do capital investido no equipamento de maior rendimento. Em seguida, o mesmo foi aplicado a um sistema de bombeamento para suprimento de um sistema de irrigação do tipo pivô central. As opções de rendimento da bomba hidráulica foram: 69,5% (bomba 1, 73% (bomba 2 e 78% (bomba 3, cujos custos de aquisição foram, respectivamente, R$ 6.176,00, R$ 8.479,00 e R$ 15.509,00. Os resultados da aplicação do modelo mostraram que: i a substituição da bomba 1 pela bomba 2 foi viável, sendo o período de recuperação de capital 3,4 anos; ii a substituição da bomba 1 pela bomba 3 foi viável, sendo o período de recuperação de capital 9,2 anos; iii a substituição da bomba 2 pela bomba 3 foi inviável, sendo o período de recuperação de capital 21,1 anos superior ao período de amortização do investimento na avaliação econômica, considerado 15 anos.In this study a mathematical model was adjusted to quantify the effect of the pump efficiency on cost variation of the pumping system in the green hourly seasonal tariff (subgroup A4 - irrigation and the investment recovery period by a more efficient pumping station. Afterwards, the same model was applied in a pumping system supplying a center pivot irrigation machine. The hydraulics pump efficiency options were: 69.5% (pump 1, 73% (pump 2 and 78% (pump 3, with acquisition costs of R$ 6,176.00, R$ 8,479.00 and R$ 15,509.00, respectively. The results of the model applied showed that: i the substitution of pump 1 for 2 was feasible, being the investment recovery period of 3.4 years; ii the substitution of bomb 1 for 3 was feasible, being the investment recovery period of 9.2 years; and iii the substitution of bomb 2 for 3 was unfeasible
RESEARCH OF THE DYNAMIC CHARACTERISTICS ON A NEW HYDRAULIC SYSTEM OF ELECTRO-HYDRAULIC HAMMER
无
2001-01-01
A new typed hydraulic system of electro-hydraulic hammer is researched and developed.By means of power bond graphs the modeling and simulation to the dynamic characteristics of the new hydraulic system are performed. The experimental research which is emphasized on the blowing stroke is also performed. It is proved from the result of simulation and experiment that this new hydraulic system possesses such advantages as simplification of structure,flexibleness of operation and reliability of working. Especially it possesses better dynamic characteristics.
Design of a laboratory hydraulic device for testing of hydraulic pumps
Pavel Máchal
2013-01-01
Full Text Available The present contribution deals with solves problem of research of testing device to monitor of hydrostatic pumps durability about dynamic loading under laboratory conditions. When carrying out the design of testing device are based on load characteristics of tractor hydraulic circuit, the individual characteristics of hydraulic components and performed calculations. Load characteristics on the tractors CASE IH Magnum 310, JOHN DEERE 8100, ZETOR FORTERRA 114 41 and Fendt 926 Vario were measured. Design of a hydraulic laboratory device is based on the need for testing new types of hydraulic pumps or various types of hydraulic fluids. When creating of hydraulic device we focused on testing hydraulic pumps used in agricultural and forestry tractors. Proportional pressure control valve is an active member of the hydraulic device, which provides change of a continuous control signal into relative pressure of operating fluid. The advantage of a designed hydraulic system is possibility of simulation of dynamic operating loading, which is obtained by measurement under real conditions, and thereby creates laboratory conditions as close to real conditions as possible. The laboratory device is constructed at the Department of Transport and Handling, Faculty of Engineering, Slovak University of Agriculture in Nitra.
Characterization of a hydraulically induced bedrock fracture
2014-01-01
Hydraulic fracturing is a controversial practice because of concerns about environmental impacts due to its widespread use in recovering unconventional petroleum and natural gas deposits. However, water-only hydraulic fracturing has been used safely and successfully for many years to increase the permeability of aquifers used for drinking and irrigation water supply. This process extends and widens existing bedrock fractures, allowing groundwater storage to increase. Researchers have studied ...
FEEDBACK LINEARISATION APPLIED ON A HYDRAULIC
Andersen, Torben Ole; Hansen, Michael Rygaard; Pedersen, Henrik C.;
2005-01-01
Generally most hydraulic systems are intrensically non-linear, why applying linear control techniques typically results in conservatively dimensioned controllers to obtain stable performance. Non-linear control techniques have the potential of overcoming these problems, and in this paper the focus...... is on developing and applying several different feedback linearisation (FL) controllers to the individual servo actuators in a hydraulically driven servo robot to evaluate and compare their possiblities and limitations. This is done based on both simulation and experimental results....
Data Analytics of Hydraulic Fracturing Data
Zhang, Jovan Yang [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Viswanathan, Hari [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Hyman, Jeffery [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Middleton, Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2016-08-11
These are a set of slides on the data analytics of hydraulic fracturing data. The conclusions from this research are the following: they proposed a permeability evolution as a new mechanism to explain hydraulic fracturing trends; they created a model to include this mechanism and it showed promising results; the paper from this research is ready for submission; they devised a way to identify and sort refractures in order to study their effects, and this paper is currently being written.
Jalali, Mohammadreza; Klepikova, Maria; Fisch, Hansruedi; Amann, Florian; Loew, Simon
2016-04-01
A decameter-scale in-situ hydraulic stimulation and circulation (ISC) experiment has been initiated by the newly-founded Swiss Competence Centre for Energy Research - Supply of Electricity (SCCER-SoE) at Nagra's Grimsel Test Site (GTS) as a part of the work-package WP1 of the Deep Underground Laboratory (DUG-Lab) initiative. The experiment area is situated in the southern part of the GTS in a low fracture density volume of the Grimsel granodiorite. The hydraulic properties of the granitic rock mass are supposed to be similar to those expected in the crystalline basement of the alpine foreland where deep enhanced geothermal systems might be developed in future. The main objectives of the multi-disciplinary experiment are to provide a high resolution pre- and post-stimulation characterization of fracture permeability and connectivity, to investigate patterns of preferential flow paths, to describe the pressure propagation during the stimulation phases and to evaluate the efficiency of the fracture-matrix heat exchanger. A comprehensive test & monitoring layout including a fair number of boreholes instrumented with a variety of sensors (e.g. pressure, strain, displacement, temperature, and seismic sensors) is designed to collect detailed data during multiple hydraulic stimulation runs. The diffusion of fluid pressure is expected to be governed mainly by the properties and geometry of the existent fracture network. The hydraulic transmissivity of fractures are in the range of 10-7 to 10-9 m2/s whereas the matrix rock has a very low hydraulic conductivity (K ˜ 10-12 m/s). As part of the stress measurement campaign during the pre-stimulation phase of the ISC experiment, a series of hydraulic fracturing (HF) and hydraulic tests in pre-existing fractures (HTPF) were conducted. The tests were accompanied by micro-seismic monitoring within several observation boreholes to investigate the initiation and propagation of the induced fractures. Together with results from over
Hydraulic Motor Driving Variable-Pitch System for Wind Turbine
Ye HUANG
2013-11-01
Full Text Available The present hydraulic variable-pitch mechanism of wind turbine uses three hydraulic cylinders to drive three crank and connecting rod mechanisms respectively; the blades are moved with the cranks. The hydraulic variable-pitch mechanism has complex structure, occupies a lot of space and its maintenance is trouble. In order to make up for the shortcomings of hydraulic cylinder variable-pitch system, the present hydraulic variable-pitch mechanism should be changed as follows: hydraulic motors are used to drive gears; gears drive blades; the electro-hydraulic proportional valves are used to control hydraulic motors. The hydraulic control part and electrical control part of variable-pitch system is redesigned. The new variable-pitch system is called hydraulic motor driving variable-pitch system. The new variable-pitch system meets the control requirements of blade pitch, makes the structure simple and its application effect is perfect.
New and improved hydraulic radius for channels of the second kind
Ali R. Vatankhah
2015-09-01
In current research a new and improved definition of hydraulic radius for closed conduits flowing partially full, is presented. This definition is efficient enough and provides powerful tool to determine the channel discharge and friction slope of uniform flow via Manning’s equation.
Ion-mediated changes of xylem hydraulic resistance in planta: fact or fiction?
Ieperen, van W.
2007-01-01
Although xylem provides an efficient transport pathway for water in plants, the hydraulic conductivity of xylem (Kh) can still influence plant water status. For decades, the Kh of functional xylem has been assumed to be constant in the short term because xylem consists of a network of dead interconn
STUDY ON AN OBJECTORIENTED FEATUREBASED CADOF HYDRAULIC MANIFOLD BLOCK
无
2000-01-01
The technique of objectoriented featurebased solid modeling and its application in the CAD of hydraulic manifold block (HMB) are discussed. The research can greatly improve the convenience and efficiency of product design for HMB, as well as for the other mechanical products.
Economics and Maximum Entropy Production
Lorenz, R. D.
2003-04-01
Price differentials, sales volume and profit can be seen as analogues of temperature difference, heat flow and work or entropy production in the climate system. One aspect in which economic systems exhibit more clarity than the climate is that the empirical and/or statistical mechanical tendency for systems to seek a maximum in production is very evident in economics, in that the profit motive is very clear. Noting the common link between 1/f noise, power laws and Self-Organized Criticality with Maximum Entropy Production, the power law fluctuations in security and commodity prices is not inconsistent with the analogy. There is an additional thermodynamic analogy, in that scarcity is valued. A commodity concentrated among a few traders is valued highly by the many who do not have it. The market therefore encourages via prices the spreading of those goods among a wider group, just as heat tends to diffuse, increasing entropy. I explore some empirical price-volume relationships of metals and meteorites in this context.
Maximum capacities of the 100-B water plant
Strand, N.O.
1953-04-27
Increases in process water flows will be needed as the current program of increasing pile power levels continues. The future process water flows that will be required are known to be beyond the present maximum capacities of component parts of the water system. It is desirable to determine the present maximum capacities of each major component part so that plans can be mode for modifications and/or additions to the present equipment to meet future required flows. The apparent hydraulic limit of the present piles is about 68,000 gpm. This figure is based on a tube inlet pressure of 400 psi, a tube flow of 34 gpm, and 2,000 effective tubes. In this document the results of tests and calculations to determine the present maximum capacities of each major component part of the 100-B water system will be presented. Emergency steam operated pumps will not be considered as it is doubtful of year around operation of a steam driven pump could be economically justified. Some possible ways to increase the process water flows of each component part of the water system to the ultimate of 68,000 gpm are given.