Calculation Method for Effect of Silt Sediment on Lifting Force of HydraulicGate
Institute of Scientific and Technical Information of China (English)
Gao Shizhao; Xu Guobin; Wang Mingbin
2015-01-01
In this paper, silt sediment is considered to be Bingham body, which is made up of coarse and fine parti-cles in front of a hydraulic gate. The coarse and fine particles provide friction and shear stress in the course of opening the gate. They constitute together the adhesion force of the sediment. Based on this viewpoint, this paper putsforward a formula for the effect of silt sediment on the lifting force. The formula includes gate weight, down-suction force, sealing rubber friction, plus-weight, water-column pressure, plus-silted-sediment weight and rolling(or sliding)-bearing friction. Finally, the verification results show that the formula has certain reliability and the calculation accu-racy can meet the need of practical engineering.
Force Balance Analysis Calculation of Downhole Hydraulic Piston Pump%井下水力活塞泵力平衡分析计算
Institute of Scientific and Technical Information of China (English)
刘乾义; 郭庆平
2012-01-01
The structure and working principle of hydraulic piston pumps is introduced* analysis and calculation of its effective displacement pump and hydraulic motor displacement, and the actual displacement and rated discharge capacity were made. The force balance equation for hydraulic piston pump was established. The P/E values were computed to obtain friction losses, which provided a basis for design and application of hydraulic piston pumps.%介绍了水力活塞泵的结构及工作原理,分析计算了其液马达排量和泵的有效排量、实际排量及额定排量,建立了水力活塞泵力平衡方程,计算得到摩阻损失和P/E值,为水力活塞泵的设计应用提供依据.
Energy Technology Data Exchange (ETDEWEB)
Corpa Masa, R.; Jimenez Varas, G.; Moreno Garcia, B.
2016-08-01
To be able to simulate the behavior of nuclear fuel under operating conditions, it is required to include all the representative loads, including the lateral hydraulic forces which were not included traditionally because of the difficulty of calculating them in a reliable way. Thanks to the advance in CFD codes, now it is possible to assess them. This study calculates the local lateral hydraulic forces, caused by the contraction and expansion of the flow due to the bow of the surrounding fuel assemblies, on of fuel assembly under typical operating conditions from a three loop Westinghouse PWR reactor. (Author)
Hydraulic forces contribute to left ventricular diastolic filling
Maksuti, Elira; Carlsson, Marcus; Arheden, Håkan; Kovács, Sándor J.; Broomé, Michael; Ugander, Martin
2017-03-01
Myocardial active relaxation and restoring forces are known determinants of left ventricular (LV) diastolic function. We hypothesize the existence of an additional mechanism involved in LV filling, namely, a hydraulic force contributing to the longitudinal motion of the atrioventricular (AV) plane. A prerequisite for the presence of a net hydraulic force during diastole is that the atrial short-axis area (ASA) is smaller than the ventricular short-axis area (VSA). We aimed (a) to illustrate this mechanism in an analogous physical model, (b) to measure the ASA and VSA throughout the cardiac cycle in healthy volunteers using cardiovascular magnetic resonance imaging, and (c) to calculate the magnitude of the hydraulic force. The physical model illustrated that the anatomical difference between ASA and VSA provides the basis for generating a hydraulic force during diastole. In volunteers, VSA was greater than ASA during 75-100% of diastole. The hydraulic force was estimated to be 10-60% of the peak driving force of LV filling (1-3 N vs 5-10 N). Hydraulic forces are a consequence of left heart anatomy and aid LV diastolic filling. These findings suggest that the relationship between ASA and VSA, and the associated hydraulic force, should be considered when characterizing diastolic function and dysfunction.
Study on Characteristics of Hydraulic Servo System for Force Control of Hydraulic Robots
Energy Technology Data Exchange (ETDEWEB)
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.
Flow-Force Compensation in a Hydraulic Valve
Lugowski, Jan
2015-01-01
Flow-reaction forces acting in hydraulic valves have been studied for many decades. Despite this, they are difficult to account for due to the complexities of the jet flow. This paper focuses only on the reduction, also referred to as compensation, of the flow force as applied to a valve spool featuring a profile of a turbine bucket. Fluid power textbooks explain the compensation taking place on such a profile by applying Newton laws of motion to the profile and deliver an equation for the magnitude and the direction of the flow force. This paper shows that both the magnitude and the direction of the compensating flow force are incorrect if calculated from the textbook equation. A corrected analysis of the dynamic forces is presented that are in agreement with earlier experiments by this author. It follows that the compensating flow force should be calculated from the static-pressure imbalance on the spool profile. That is, not Newton but Pascal law should be applied to calculate the compensating flow force.
Precision Force Control for an Electro-Hydraulic Press Machine
Directory of Open Access Journals (Sweden)
Hong-Ming Chen
2014-08-01
Full Text Available This thesis is primarily intended to design a PC-based control system to control the force of an electro-hydraulic servo press system for implementing precision force control. The main feature is to develop a composite control by using the relief valve and the flow servo valve. Using feedback from a force sensor, a fuzzy controller was designed with LabVIEW software as the system control core for achieving a precision force control for the hydraulic cylinder on its travel and output. The weakness of hydraulic systems is that hydraulic oil is compressible and prone to leaking, and its characteristics can vary with oil temperature, thus making it difficult for a general linear controller to achieve accurate control. Therefore, a fuzzy controller was designed with LabVIEW along with a NI-PCI_6221 interface card and a load cell to control the servo valve flow and the relief valve to control the pressure source. The testing results indicate that accurate force control output of an electro-hydraulic servo press system can be obtained.
Optimised Iteration in Coupled Monte Carlo - Thermal-Hydraulics Calculations
Hoogenboom, J. Eduard; Dufek, Jan
2014-06-01
This paper describes an optimised iteration scheme for the number of neutron histories and the relaxation factor in successive iterations of coupled Monte Carlo and thermal-hydraulic reactor calculations based on the stochastic iteration method. The scheme results in an increasing number of neutron histories for the Monte Carlo calculation in successive iteration steps and a decreasing relaxation factor for the spatial power distribution to be used as input to the thermal-hydraulics calculation. The theoretical basis is discussed in detail and practical consequences of the scheme are shown, among which a nearly linear increase per iteration of the number of cycles in the Monte Carlo calculation. The scheme is demonstrated for a full PWR type fuel assembly. Results are shown for the axial power distribution during several iteration steps. A few alternative iteration method are also tested and it is concluded that the presented iteration method is near optimal.
Development of Force Reflecting Joystick for Hydraulic Excavator
Ahn, Kyoungkwan
In teleoperation field robotic system such as hydraulically actuated robotic excavator, the maneuverability and convenience is the most important in the operation of robotic excavator. Particularly the force information is important in dealing with digging and leveling operation in the teleoperated excavator. This paper presents a new force reflecting joystick in a velocity-force type bilateral teleoperation system. The master system is electrical joystick and the slave system is hydraulic cylinder. Particularly pneumatic motor is used newly in the master joystick for force reflection and the information of the pressure of slave cylinder is measured and utilized as force feedback signal. This paper also proposes a novel force-reflection gain selecting algorithm based on artificial neural network. Finally a series of experiments are conducted under various load conditions using a laboratory-made one axis slave cylinder and load simulator.
Hydraulic forces caused by annular pressure seals in centrifugal pumps
Iino, T.; Kaneko, H.
1980-01-01
The hydraulic forces caused by annular pressure seals were investigated. The measured inlet and exit loss coefficients of the flow through the seals were much smaller than the conventional values. The results indicate that the damping coefficient and the inertia coefficient of the fluid film in the seal are not affected much by the rotational speed or the eccentricity of the rotor, though the stiffness coefficient seemed to be influenced by the eccentricity.
Axial force calculation of passive magnetic bearing
National Research Council Canada - National Science Library
Vučković Ana N; Raičević Nebojša B; Ilić Saša S; Aleksić Slavoljub R; Perić Mirjana T
2014-01-01
.... Configuration like this one resembles the one passive magnetic bearing has. Force calculation is performed using semi analytical approach based on fictitious magnetization charges and discretization technique...
Project calculation of the steering mechanism hydraulic servo control in motor vehicles
Directory of Open Access Journals (Sweden)
Zoran Đukan Majkić
2013-10-01
Full Text Available Hydraulic servo controls are designed to facilitate rotation in place without providing increased ppower to steering wheels. In the initial design phase, the dimensions required for control systems are usually obtained through the calculation of their load when wheels rotate in place, where the torque is calculated empirically. The starting point in the project calculation is thus to determine the hydraulic power steering torque torsional resistance which is then used to determine the maximum value of force i.e. the torque on the stering wheel. The calculation of the control system servo control consists of determining the basic parameters, the required pump capacity, the main dimensions of the hub and the pipeline and the conditions for the stability of the system control mechanism. Introduction The aim of the calculation of the steering control system is to determine the basic parameters of its components which ensure the fulfilment of requirements of the control system. Calculations are performed in several stages with a simultaneous detailed constructive analysis of the control system leading to the best variant. At each stage, design and control calculations of the hydraulic servo of the steering mechanism are performed. The design allows the computation to complete the selection of basic dimensions of the amplifer elements, starting from the approved scheme and the basic building loads of approximate values. Calculations control is carried out to clarify the structural solution and to obtain the output characteristics of the control amplifier which are applied in the estimation of potential properties of the structure. Project calculation Baseline data must be sufficiently reliable, ie. must correspond to the construction characteristics of the vehicle design and the control system as well as to service conditions..A proper deterimination of the torque calculation of torsional resistance in wheels is of utmost importance. Moment of
Multifragmentation calculated with relativistic forces
Feldmeier, H; Papp, G
1995-01-01
A saturating hamiltonian is presented in a relativistically covariant formalism. The interaction is described by scalar and vector mesons, with coupling strengths adjusted to the nuclear matter. No explicit density depe ndence is assumed. The hamiltonian is applied in a QMD calculation to determine the fragment distribution in O + Br collision at different energies (50 -- 200 MeV/u) to test the applicability of the model at low energies. The results are compared with experiment and with previous non-relativistic calculations. PACS: 25.70Mn, 25.75.+r
Hydraulic calculation of gravity transportation pipeline system for backfill slurry
Institute of Scientific and Technical Information of China (English)
ZHANG Qin-li; HU Guan-yu; WANG Xin-min
2008-01-01
Taking cemented coal gangue pipeline transportation system in Suncun Coal Mine, Xinwen Mining Group, Shandong Province, China, as an example, the hydraulic calculation approaches and process about gravity pipeline transportation of backfill slurry were investigated. The results show that the backfill capability of the backfill system should be higher than 74.4m3/h according to the mining production and backfill times in the mine; the minimum velocity (critical velocity) and practical working velocity of the backfill slurry are 1.44 and 3.82m/s, respectively. Various formulae give the maximum ratio of total length to vertical height of pipeline (L/H ratio) of the backfill system of 5.4, and then the reliability and capability of the system can be evaluated.
Reciprocity Theorems for Ab Initio Force Calculations
Wei, C; Mele, E J; Rappe, A M; Lewis, Steven P.; Rappe, Andrew M.
1996-01-01
We present a method for calculating ab initio interatomic forces which scales quadratically with the size of the system and provides a physically transparent representation of the force in terms of the spatial variation of the electronic charge density. The method is based on a reciprocity theorem for evaluating an effective potential acting on a charged ion in the core of each atom. We illustrate the method with calculations for diatomic molecules.
The influence of hydraulic forces on the selection of structural form
Glerum, A.; Schippers, J.
1981-01-01
Besides that the hydraulic forces have an influence on the structure, the shape of the structure may often influence the hydraulic loads as well. A distinction should be made between hydrostatic forces which are for instance caused by a difference in head between two water levels and dynamic forces
Isotope Production Facility Conceptual Thermal-Hydraulic Design Review and Scoping Calculations
Energy Technology Data Exchange (ETDEWEB)
Pasamehmetoglu, K.O.; Shelton, J.D.
1998-08-01
The thermal-hydraulic design of the target for the Isotope Production Facility (IPF) is reviewed. In support of the technical review, scoping calculations are performed. The results of the review and scoping calculations are presented in this report.
Force Control Strategies in Hydraulically Actuated Legged Robots
Directory of Open Access Journals (Sweden)
Hector Montes
2016-03-01
Full Text Available In this contribution, several strategies of force control have been proposed to be implemented and evaluated in ROBOCLIMBER, a quadruped robot of large dimensions. A first group of strategies proposed in this paper is based on impedance control, which is intended to adapt the foot-ground contact forces according to the experimentally specified damping ratio and the undamped natural frequency. A second control strategy of interest for many practical cases is called the parallel force/position control, which has one inner loop position control and two external control loops, one of force and another of position. A third group of control strategies is the posture stabilization for ROBOCLIMBER using the feedback of the ZMP calculation and the position of its legs. Finally, a control strategy for the control of a quasi-static gait using ZMP feedback is proposed and tested by simulation.
Calculating Free Energies Using Average Force
Darve, Eric; Pohorille, Andrew; DeVincenzi, Donald L. (Technical Monitor)
2001-01-01
A new, general formula that connects the derivatives of the free energy along the selected, generalized coordinates of the system with the instantaneous force acting on these coordinates is derived. The instantaneous force is defined as the force acting on the coordinate of interest so that when it is subtracted from the equations of motion the acceleration along this coordinate is zero. The formula applies to simulations in which the selected coordinates are either unconstrained or constrained to fixed values. It is shown that in the latter case the formula reduces to the expression previously derived by den Otter and Briels. If simulations are carried out without constraining the coordinates of interest, the formula leads to a new method for calculating the free energy changes along these coordinates. This method is tested in two examples - rotation around the C-C bond of 1,2-dichloroethane immersed in water and transfer of fluoromethane across the water-hexane interface. The calculated free energies are compared with those obtained by two commonly used methods. One of them relies on determining the probability density function of finding the system at different values of the selected coordinate and the other requires calculating the average force at discrete locations along this coordinate in a series of constrained simulations. The free energies calculated by these three methods are in excellent agreement. The relative advantages of each method are discussed.
FORCE FEEDBACK MODEL OF ELECTRO-HYDRAULIC SERVO TELE-OPERATION ROBOT BASED ON VELOCITY CONTROL
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
The tele-operation robotic system which consists of an excavator as the construction robot, and two joysticks for operating the robot from a safe place are useful for performing restoration in damaged areas. In order to accomplish a precise task, the operator needs to feel a realistic sense of task force brought about from a feedback force between the fork glove of slave robot and unfamiliar environment. A novel force feedback model is proposed based on velocity control of cylinder to determine environment force acting" on fork glove. Namely, the feedback force is formed by the error of displacement of joystick with velocity and driving force of piston, and the gain is calculated by the driving force and threshold of driving force of hydraulic cylinder. Moreover, the variable gain improved algorithm is developed to overcome the defect for grasping soft object. Experimental results for fork glove freedom of robotic system are provided to demonstrate the developed algorithm is available for grasping soft object.
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)…
EVALUATION OF HYDRAULIC CONDUCTIVITIES CALCULATED FROM MULTIPORT-PERMEAMETER MEASUREMENTS
A multiport permeameter was developed for use in estimating hydraulic conductivity over intact sections of aquifer core using the core liner as the permeameter body. Six cores obtained from one borehole through the upper 9 m of a stratified glacial-outwash aquifer were used to ev...
Cao, Yang-Bing; Feng, Xia-Ting; Yan, E.-Chuan; Chen, Gang; Lü, Fei-fei; Ji, Hui-bin; Song, Kuang-Yin
2016-05-01
Knowledge of the fracture hydraulic aperture and its relation to the mechanical aperture and normal stress is urgently needed in engineering construction and analytical research at the engineering field scale. A new method based on the in situ borehole camera measurement and borehole water-pressure test is proposed for the calculation of the fracture hydraulic aperture. This method comprises six steps. The first step is to obtain the equivalent hydraulic conductivity of the test section from borehole water-pressure tests. The second step is a tentative calculation to obtain the qualitative relation between the reduction coefficient and the mechanical aperture obtained from borehole camera measurements. The third step is to choose the preliminary reduction coefficient for obtaining the initial hydraulic aperture. The remaining three steps are to optimize, using the genetic algorithm, the hydraulic apertures of fractures with high uncertainty. The method is then applied to a fractured granite engineering area whose purpose is the construction of an underground water-sealed storage cavern for liquefied petroleum gas. The probability distribution characteristics of the hydraulic aperture, the relationship between the hydraulic aperture and the mechanical aperture, the hydraulic aperture and the normal stress, and the differences between altered fractures and fresh fractures are all analyzed. Based on the effects of the engineering applications, the method is proved to be feasible and reliable. More importantly, the results of the hydraulic aperture obtained in this paper are different from those results elicited from laboratory tests, and the reasons are discussed in the paper.
Velocity Potential in Engineering Hydraulics versus Force Potential in Groundwater Dynamics
Weyer, K.
2013-12-01
Within engineering practice, the calculation of subsurface flow is dominated by the mathematical pseudo-physics of the engineer's adaptation of continuum methods to mechanics. Continuum mechanics rose to prominence in the 19th century in an successful attempt to solve practical engineering problems. To that end were put in place quite a number of simplifications in geometry and the properties of water and other fluids, as well as simplifications of Darcy's equation, in order to find reasonable answers to practical problems by making use of analytical equations. The proof of the correctness of the approach and its usefulness was in the practicability of results obtained. In the 1930s, a diametrically-opposed duality developed in the theoretical derivation of the laws of subsurface fluid flow between Muskat's (1937) velocity potential (engineering hydraulics) and Hubbert's (1940) force potential. The conflict between these authors lasted a lifetime. In the end Hubbert stated on one occasion that Muskat formulates a refined mathematics but does not know what it means in physical terms. In this author's opinion that can still be said about the application of continuum mechanics by engineers to date, as for example to CO2 sequestration, regional groundwater flow, oil sands work, and geothermal studies. To date, engineering hydraulics is best represented by Bear (1972) and de Marsily (1986). In their well-known textbooks, both authors refer to Hubbert's work as the proper way to deal with the physics of compressible fluids. Water is a compressible fluid. The authors then ignore, however, their own insights (de Marsily states so explicitly, Bear does not) and proceed to deal with water as an incompressible fluid. At places both authors assume the pressure gradients to be the main driving force for flow of fluids in the subsurface. That is not, however, the case. Instead the pressure potential forces are caused by compression initiated by unused gravitational energy not
Steady-State Flow-Force Compensation in a Hydraulic Spool Valve
Lugowski, Jan
2013-01-01
A high-speed jet flowing inside of a partially-open hydraulic valve is accompanied by a reaction force, also referred to as flow force. The nature of this force has remained a mystery despite an extensive research effort spanning many decades. The momentum theory on the flow force by Lee and Blackburn (1952) explains the origin of the flow force and offers a design solution to shape the valve spool as a turbine bucket. It provides a model to calculate the compensated flow force as well. This paper shows that the model applies to a different flow case due to incorrect assumptions made. A corrected equation is presented based on a detailed analysis of the static-pressure distribution in the valve cavity as well as on a literature review of pressure loss in diffusers and nozzles. The new equation is based on the compensation taking place upstream of the valve orifice, not downstream as assumed by the momentum theory. The new model can be applied to chamfers or notches on the valve spool without the need to machi...
Robust Force Control of a 6-Link Electro-Hydraulic Manipulator
Ahn, Kyoungkwan; Yokota, Shinichi
Uninterrupted power supply has become indispensable during the maintenance task of active electric power lines as a result of today's highly information-oriented society and increasing demand of electric utilities. This maintenance task has the risk of electric shock and the danger of falling from high place. Therefore it is necessary to realize an autonomous robot system using electro-hydraulic manipulator because hydraulic manipulators have the advantage of electric insulation and power/mass density. Meanwhile an electro-hydraulic manipulator using hydraulic actuators has many nonlinear elements, and its parameter fluctuations are greater than those of an electrically driven manipulator. So it is relatively difficult to realize not only stable contact work but also accurate force control for the autonomous assembly tasks using hydraulic manipulators. In this paper, the robust force control of a 6-link electro-hydraulic manipulator system used in the real maintenance task of active electic line is examined in detail. A nominal model for the system is obtained from experimental frequency responses of the system, and the deviation of the manipulator system from the nominal model is derived by a multiplicative uncertainty. Robust disturbance observers for force control are designed using this information in an H∞ framework, and implemented on the two different setups. Experimental results show that highly robust force tracking by a 6-link electro-hydraulic manipulator could be achieved even if the stiffness of environment and the shape of wall change.
Energy Technology Data Exchange (ETDEWEB)
Pozdniakov, Sergey; Tsang, Chin-Fu
2004-01-02
In this paper, we consider an approach for estimating the effective hydraulic conductivity of a 3D medium with a binary distribution of local hydraulic conductivities. The medium heterogeneity is represented by a combination of matrix medium conductivity with spatially distributed sets of inclusions. Estimation of effective conductivity is based on a self-consistent approach introduced by Shvidler (1985). The tensor of effective hydraulic conductivity is calculated numerically by using a simple system of equations for the main diagonal elements. Verification of the method is done by comparison with theoretical results for special cases and numerical results of Desbarats (1987) and our own numerical modeling. The method was applied to estimating the effective hydraulic conductivity of a 2D and 3D fractured porous medium. The medium heterogeneity is represented by a combination of matrix conductivity and a spatially distributed set of highly conductive fractures. The tensor of effective hydraulic conductivity is calculated for parallel- and random-oriented sets of fractures. The obtained effective conductivity values coincide with Romm's (1966) and Snow's (1969) theories for infinite fracture length. These values are also physically acceptable for the sparsely-fractured-medium case with low fracture spatial density and finite fracture length. Verification of the effective hydraulic conductivity obtained for a fractured porous medium is done by comparison with our own numerical modeling for a 3D case and with Malkovsky and Pek's (1995) results for a 2D case.
Calculation of Water Supply to Hydraulic Jet Devices
Directory of Open Access Journals (Sweden)
M. V. Krautsou
2006-01-01
Full Text Available Dependence for calculation of working fluid supply to water-air ejector is proposed. The dependence has been derived via analysis and processing of data being obtained by experimental research of water-jet devices.
Modeling Hydraulic Responses to Meteorological Forcing: fromCanopy to Aquifer
Energy Technology Data Exchange (ETDEWEB)
Pan, Lehua; Jin, Jiming; Miller, Norman; Wu, Yu-Shu; Bodvarsson,Gudmundur
2007-02-08
An understanding of the hydrologic interactions amongatmosphere, land surface, and subsurface is one of the keys tounderstanding the water cycling system that supports our life system onearth. Properly modeling such interactionsis a difficult task because oftheinherent coupled processes and complex feedback structures amongsubsystems. In this paper, we present a model that simulates thelandsurface and subsurface hydrologic response to meteorological forcing.This model combines a state of the art landsurface model, the NCARCommunity Land Model version 3 (CLM3), with a variablysaturatedgroundwater model, the TOUGH2, through an internal interfacethat includes flux and state variables shared by the two submodels.Specifically, TOUGH2, in its simulation, uses infiltration, evaporation,and rootuptake rates, calculated by CLM3, as source/sink terms? CLM3, inits simulation, uses saturation and capillary pressure profiles,calculated by TOUGH2, as state variables. This new model, CLMT2,preserves the best aspects of both submodels: the state of the artmodeling capability of surface energy and hydrologic processes from CLM3and the more realistic physical process based modeling capability ofsubsurface hydrologic processes from TOUGH2. The preliminary simulationresults show that the coupled model greatly improves the predictions ofthe water table, evapotranspiration, surface temperature, and moisture inthe top 20 cm of soil at a real watershed, as evaluated from 18 years ofobserved data. The new model is also ready to be coupled with anatmospheric simulation model, representing one of the first models thatare capable to simulate hydraulic processes from top of the atmosphere todeep ground.
CALCULATION OF TENSION FORCE OF BELT CONVEYOR
Directory of Open Access Journals (Sweden)
Ismet Ibishi
2012-12-01
Full Text Available In this paper is done the explanation on tension fashion of the belt conveyor which is employed in Kosovo Energy Corporation – KEK, for coal transportation to provide electric power plant. The aim of the paper enables to recognize tension forces not to pass with deformation of belt so that this problem will damage the workingprocess. Work principle is based on initial tension and tension during working process. The fact is known that the tension starts from the carriage on the way to tension mechanization, so forces on the rope passing through pulley there has to dominate the friction coefficient. All this process is related to economy of transportationmechanism.
Calculation of noncontact forces between silica nanospheres.
Sun, Weifu; Zeng, Qinghua; Yu, Aibing
2013-02-19
Quantification of the interactions between nanoparticles is important in understanding their dynamic behaviors and many related phenomena. In this study, molecular dynamics simulation is used to calculate the interaction potentials (i.e., van der Waals attraction, Born repulsion, and electrostatic interaction) between two silica nanospheres of equal radius in the range of 0.975 to 5.137 nm. The results are compared with those obtained from the conventional Hamaker approach, leading to the development of modified formulas to calculate the van der Waals attraction and Born repulsion between nanospheres, respectively. Moreover, Coulomb's law is found to be valid for calculating the electrostatic potential between nanospheres. The developed formulas should be useful in the study of the dynamic behaviors of nanoparticle systems under different conditions.
An assessment of the CORCON-MOD3 code. Part 1: Thermal-hydraulic calculations
Energy Technology Data Exchange (ETDEWEB)
Strizhov, V.; Kanukova, V.; Vinogradova, T.; Askenov, E. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Nuclear Safety; Nikulshin, V. [Russian Research Center, Moscow (Russian Federation). Kurchatov Inst.
1996-09-01
This report deals with the subject of CORCON-Mod3 code validation (thermal-hydraulic modeling capability only) based on MCCI (molten core concrete interaction) experiments conducted under different programs in the past decade. Thermal-hydraulic calculations (i.e., concrete ablation, melt temperature, melt energy, concrete temperature, and condensible and non-condensible gas generation) were performed with the code, and compared with the data from 15 experiments, conducted at different scales using both simulant (metallic and oxidic) and prototypic melt materials, using different concrete types, and with and without an overlying water pool. Sensitivity studies were performed in a few cases involving, for example, heat transfer from melt to concrete, condensed phase chemistry, etc. Further, special analysis was performed using the ACE L8 experimental data to illustrate the differences between the experimental and the reactor conditions, and to demonstrate that with proper corrections made to the code, the calculated results were in better agreement with the experimental data. Generally, in the case of dry cavity and metallic melts, CORCON-Mod3 thermal-hydraulic calculations were in good agreement with the test data. For oxidic melts in a dry cavity, uncertainties in heat transfer models played an important role for two melt configurations--a stratified geometry with segregated metal and oxide layers, and a heterogeneous mixture. Some discrepancies in the gas release data were noted in a few cases.
Sensitivity of aerosol radiative forcing calculations to spectral resolution
Energy Technology Data Exchange (ETDEWEB)
Grant, K.E.
1996-10-01
Potential impacts of aerosol radiative forcing on climate have generated considerable recent interest. An important consideration in estimating the forcing from various aerosol components is the spectral resolution used for the solar radiative transfer calculations. This paper examines the spectral resolution required from the viewpoint of overlapping spectrally varying aerosol properties with other cross sections. A diagnostic is developed for comparing different band choices, and the impact of these choices on the radiative forcing calculated for typical sulfate and biomass aerosols was investigated.
Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong
2016-05-01
Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this
The role of magnetoplasmons in Casimir force calculations
Esquivel-Sirvent, R; Palomino-Ovando, M A; Cocoletzi, G H
2009-01-01
In this paper we review the role of magneto plasmon polaritons in the Casimir force calculations. By applying an external constant magnetic field a strong optical anisotropy is induced on two parallel slabs reducing the reflectivity and thus the Casimir force. As the external magnetic field increases, the Casimir force decreases. Thus, with an an external magnetic field the Casimir force can be controlled.The calculations are done in the Voigt configuration where the magnetic field is parallel to the slabs. In this configuration the reflection coefficients for TE and TM modes do not show mode conversion.
Magnetic Field and Force Calculations for ATLAS Asymmetrical Structure
Nessi, Marzio
2001-01-01
Magnetic field distortion in the assymetrical ATLAS structure are calculated. Magnetic forces in the system are estimated. 3D magnetic field simulation by the Opera3D code for symmetrical and asymmetrical systems is used.
Energy Technology Data Exchange (ETDEWEB)
Slater, CO
2005-09-08
To aid in the determinations of reactivity worths for target materials in a proposed High Flux Isotope Reactor (HFIR) target configuration containing two additional hydraulic tubes, the worths of cadmium rabbits within the current hydraulic tube were calculated using a reference model of the HFIR and the MCNP5 computer code. The worths were compared to measured worths for both static and ejection experiments. After accounting for uncertainties in the calculations and the measurements, excellent agreement between the two was obtained. Computational and measurement limitations indicate that accurate estimation of worth is only possible when the worth exceeds 10 cents. Results indicate that MCNP5 and the reactor model can be used to predict reactivity worths of various samples when the expected perturbations are greater than 10 cents. The level of agreement between calculation and experiment indicates that the accuracy of such predictions would be dependent solely on the quality of the nuclear data for the materials to be irradiated. Transients that are approximated by ''piecewise static'' computational models should likewise have an accuracy that is dependent solely on the quality of the nuclear data.
NUMERICAL CALCULATION OF SOLID-LIQUID TWO PHASE FLOW BETWEEN STAY VANES IN HYDRAULIC TURBINE
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
In this paper, an energy equation of silt-laden water flow is educed based on the energy equation of continuum fluid flow. The dissipation functions of liquid phase and solid phase are presented respectively. Then the extremity law of energy dissipation rate is introduced for the research of the silt-laden water flow and a new mathematical model is developed. The corresponding procedure based on the finite difference method (FDM) is developed to calculate the two phase flow in hydraulic turbine. The method is applied to analyze the silt-laden water flow between stay vanes, and the numerical results are in good agreement with the experimental ones.
J. S. Rao; E. Raghavacharyulu; Seshadri, V.; V.V.R. Rao
1983-01-01
Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic a...
Directory of Open Access Journals (Sweden)
Chao Hu
2015-04-01
Full Text Available Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak, cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laser-scanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation project quality assessment with the laser scanning technology can be reduced by 70%−90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.
Experimental Validation of Modelled Fluid Forces in Fast Switching Hydraulic On/Off Valves
DEFF Research Database (Denmark)
Nørgård, Christian; Bech, Michael Møller; Roemer, Daniel Beck;
2015-01-01
A prototype of a fast switching valve for a digital hydraulic machine has been designed and manufactured. The valve is composed of an annular seat plunger connected with a moving coil actuator as the force producing element. The valve prototype is designed for flow rates of 600 l/min with less than...... 0.5 bar pressure drop, and the models predicts a switching time in the region of a millisecond with a travel length of 3.5 mm using an average power of 250 W. The total machine efficiency when neglecting losses not related to the valves is above 98 %. The objective of this paper is to experimentally...... validate a transient computational fluid dynamics (CFD) model of the fluid forces that oppose the valve plunger when moving rapidly through the surrounding oil during switching. Due to the fast switching of the valve, the fluid forces which oppose plunger movement increases drastically as the plunger...
Nuclear forces and ab initio calculations of atomic nuclei
Meißner, Ulf-G.
2014-01-01
Nuclear forces and the nuclear many-body problem have been some of Gerry Brown's main topics in his so productive life as a theoretical physicist. In this talk, I outline how Gerry's work laid the foundations of the modern theory of nuclear forces and ab initio calculations of atomic nuclei. I also present some recent developments obtained in the framework of nuclear lattice simulations.
Unbalanced Magnetic Force Calculation in Brushless DC Motors
Directory of Open Access Journals (Sweden)
Z. Valipoor
2015-03-01
Full Text Available In this paper, an analytical method to calculate the unbalance magnetic pull forces (UMP due to the eccentricity of the rotor with considering the slots impact, is presented. Unbalanced magnetic pull is important because it affects the wear on the bearings as well as noise and vibration. The results of the analytical method, using finite element analysis for a prototype motor, were valid. Some force harmonics have the potential to produce noise and vibration. In order to detect harmonics of unbalance magnet forces, Depending on the fault frequency, the stator currents and spectrum of the vibrations have been analyzed
Non-local thin films in Casimir force calculations
Esquivel, R
2005-01-01
he Casimir force is calculated between plates with thin metallic coating. Thin films are described with spatially dispersive (nonlocal) dielectric functions. For thin films the nonlocal effects are more relevant than for half-spaces. However, it is shown that even for film thickness smaller than the mean free path for electrons, the difference between local and nonlocal calculations of the Casimir force is of the order of a few tenths of a percent. Thus the local description of thin metallic films is adequate within the current experimental precision and range of separations.
Frequency-dependent Drude damping in Casimir force calculations
Energy Technology Data Exchange (ETDEWEB)
Esquivel-Sirvent, R, E-mail: raul@fisica.unam.m [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apdo. Postal 20-364, Mexico D.F. 01000 (Mexico)
2009-04-01
The Casimir force is calculated between Au thin films that are described by a Drude model with a frequency dependent damping function. The model parameters are obtained from available experimental data for Au thin films. Two cases are considered; annealed and nonannealed films that have a different damping function. Compared with the calculations using a Drude model with a constant damping parameter, we observe changes in the Casimir force of a few percent. This behavior is only observed in films of no more than 300 A thick.
Energy Technology Data Exchange (ETDEWEB)
Bailey, William J.
1996-12-31
This Dr. ing. thesis covers a study of drilling hydraulics offshore. The purpose of drilling hydraulics is to provide information about downhole pressure, suitable surface pump rates, the quality of hole cleaning and optimum tripping speeds during drilling operations. Main fields covered are drilling hydraulics, fluid characterisation, pressure losses, and equivalent circulating density. 197 refs., 23 figs., 22 tabs.
Directory of Open Access Journals (Sweden)
Wei Zhang
2017-05-01
Full Text Available As a key component of hydraulic control systems, hydraulic servovalves influence their performance significantly. Unpredictable self-excited noise inside hydraulic servovalves may cause instability and even failure. Being functional, with higher saturation magnetization and increased viscosity when exposed to a magnetic field, magnetic fluids (MFs have been widely used in dampers, sealing, and biomedical treatment. In this paper, magnetic fluids are applied in the torque motor of a hydraulic servovalve to exert damping and resistance for vibration and noise suppression. Construction of the torque motor armature with magnetic fluids is introduced and the forces due to magnetic fluids on the torque motor armature are studied. Based on a bi-viscosity-constituted relationship, a mathematical model of the damping force from magnetic fluids is built when magnetic fluids are filled in the working gaps of the torque motor. Measurements of the properties of an Fe3O4 composite magnetic fluid are carried out to calculate the parameters of this mathematical model and to investigate the influence of magnetic fluids on the vibration characteristics of the armature assembly. The simulated and tested harmonic responses of the armature with and without magnetic fluids show the good suppression effects of magnetic fluids on the self-excited noise inside the servovalve.
Nonlocal thin films in calculations of the Casimir force
Esquivel-Sirvent, R.; Svetovoy, V.B.
2005-01-01
The Casimir force is calculated between plates with thin metallic coating. Thin films are described with spatially dispersive (nonlocal) dielectric functions. For thin films the nonlocal effects are more relevant than for half-spaces. However, it is shown that even for film thickness smaller than th
Energy Technology Data Exchange (ETDEWEB)
Kalin, J., E-mail: jan.kalin@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Petkovsek, B., E-mail: borut.petkovsek@zag.s [Slovenian National Building and Civil Engineering Institute, Dimiceva 12, SI-1000 Ljubljana (Slovenia); Montarnal, Ph., E-mail: philippe.montarnal@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Genty, A., E-mail: alain.genty@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Deville, E., E-mail: estelle.deville@cea.f [CEA/Saclay, DM2S/SFME/LSET, Gif-sur-Yvette, 91191 cedex (France); Krivic, J., E-mail: jure.krivic@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia); Ratej, J., E-mail: joze.ratej@geo-zs.s [Geological Survey of Slovenia, Dimiceva 14, SI-1000 Ljubljana (Slovenia)
2011-04-15
In the past years the Slovenian Performance Analysis/Safety Assessment team has performed many generic studies for the future Slovenian low and intermediate level waste repository, most recently a Special Safety Analysis for the Krsko site. The modelling approach was to split the problem into three parts: near-field (detailed model of the repository), far-field (i.e., geosphere) and biosphere. In the Special Safety Analysis the code used to perform the near-field calculations was Hydrus2D. Recently the team has begun a cooperation with the French Commisariat al'Energie Atomique/Saclay (CEA/Saclay) and, as a part of this cooperation, began investigations into using the Alliances numerical platform for near-field calculations in order to compare the overall approach and calculated results. The article presents the comparison between these two codes for a silo-type repository that was considered in the Special Safety Analysis. The physical layout and characteristics of the repository are presented and a hydraulic and transport model of the repository is developed and implemented in Alliances. Some analysis of sensitivity to mesh fineness and to simulation timestep has been preformed and is also presented. The compared quantity is the output flux of radionuclides on the boundary of the model. Finally the results from Hydrus2D and Alliances are compared and the differences and similarities are commented.
Osuský, F.; Bahdanovich, R.; Farkas, G.; Haščík, J.; Tikhomirov, G. V.
2017-01-01
The paper is focused on development of the coupled neutronics-thermal hydraulics model for the Gas-cooled Fast Reactor. It is necessary to carefully investigate coupled calculations of new concepts to avoid recriticality scenarios, as it is not possible to ensure sub-critical state for a fast reactor core under core disruptive accident conditions. Above mentioned calculations are also very suitable for development of new passive or inherent safety systems that can mitigate the occurrence of the recriticality scenarios. In the paper, the most promising fuel material compositions together with a geometry model are described for the Gas-cooled fast reactor. Seven fuel pin and fuel assembly geometry is proposed as a test case for coupled calculation with three different enrichments of fissile material in the form of Pu-UC. The reflective boundary condition is used in radial directions of the test case and vacuum boundary condition is used in axial directions. During these condition, the nuclear system is in super-critical state and to achieve a stable state (which is numerical representation of operational conditions) it is necessary to decrease the reactivity of the system. The iteration scheme is proposed, where SCALE code system is used for collapsing of a macroscopic cross-section into few group representation as input for coupled code NESTLE.
Effective source approach to self-force calculations
Energy Technology Data Exchange (ETDEWEB)
Vega, Ian [Department of Physics, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Wardell, Barry [Max-Planck-Institut fuer Gravitationphysik, Albert-Einstein-Institut, 14476 Potsdam (Germany); Diener, Peter, E-mail: ianvega@uoguelph.ca, E-mail: barry.wardell@aei.mpg.de, E-mail: diener@cct.lsu.edu [Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803 (United States)
2011-07-07
Numerical evaluation of the self-force on a point particle is made difficult by the use of delta functions as sources. Recent methods for self-force calculations avoid delta functions altogether, using instead a finite and extended 'effective source' for a point particle. We provide a review of the general principles underlying this strategy, using the specific example of a scalar point charge moving in a black hole spacetime. We also report on two new developments: (i) the construction and evaluation of an effective source for a scalar charge moving along a generic orbit of an arbitrary spacetime, and (ii) the successful implementation of hyperboloidal slicing that significantly improves on previous treatments of boundary conditions used for effective-source-based self-force calculations. Finally, we identify some of the key issues related to the effective source approach that will need to be addressed by future work.
Effective source approach to self-force calculations
Vega, Ian; Diener, Peter
2011-01-01
Numerical evaluation of the self-force on a point particle is made difficult by the use of delta functions as sources. Recent methods for self-force calculations avoid delta functions altogether, using instead a finite and extended "effective source" for a point particle. We provide a review of the general principles underlying this strategy, using the specific example of a scalar point charge moving in a black hole spacetime. We also report on two new developments: (i) the construction and evaluation of an effective source for a scalar charge moving along a generic orbit of an arbitrary spacetime, and (ii) the successful implementation of hyperboloidal slicing that significantly improves on previous treatments of boundary conditions used for effective-source-based self-force calculations. Finally, we identify some of the key issues related to the effective source approach that will need to be addressed by future work.
Directory of Open Access Journals (Sweden)
Dorian Nedelcu
2015-07-01
Full Text Available The paper presents the Hydro Hill Chart - Francis module application, used to calculate the hill chart of the Pelton, Francis and Kaplan hydraulic turbine models, by processing the data measured on the stand. After describing the interface and menu, the input data is graphically presented and the universal characteristic for measuring scenarios ao=const. and n11=const is calculated. Finally, the two calculated hill charts are compared through a graphical superimposition of the isolines.
Directory of Open Access Journals (Sweden)
Daniel O. Baun
2003-01-01
Full Text Available A comparison is made between the characteristics of the measured lateral impeller forces and the hydraulic performances of a four- and a five-vane impeller, each operating in a spiral volute, a concentric volute, and a double volute. The pump's rotor was supported in magnetic bearings. In addition to supporting and controlling the rotor motion, the magnetic bearings also served as active load cells and were used to measure the impeller forces acting on the pump's rotor. The lateral impeller force characteristics, as a function of a normalized flow coefficient, were virtually identical in the four- and five-vane impellers in each respective volute type. The measured impeller forces for each volute type were compared with correlations in the literature. The measured forces from the double volute configurations agreed with the forces from a correlation model over the full flow range. Single volute configurations compared well with the predictions of a published correlation at high flow rates, ϕ/ϕn>0.5. Concentric volute configurations compared well with a published correlation at low flow rates, ϕ/ϕn<0.4. The head-versus-flow characteristics of the four-vane impeller in each volute type were stable over a greater flow range than the corresponding characteristics of the five-vane impeller. At higher flow rates in the stable region of the head's characteristic curves near the best efficiency point, the five-vane impeller produced higher head than did the four-vane impeller in each volute type.
Rao, J. S.; Raghavacharyulu, E.; Seshadri, V.; Rao, V. V. R.
1983-10-01
Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic analogy is described. A flat plate stage is simulated on the rotating water table, and the results obtained are presented.
Directory of Open Access Journals (Sweden)
J. S. Rao
1983-10-01
Full Text Available Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic analogy ia described. A flat plate stage is simulated on the rotating water table, and the results obtalned are presented.
Directory of Open Access Journals (Sweden)
Dorian Nedelcu
2015-07-01
Full Text Available The paper presents the HydroHillChart - Pelton module application, used to calculate the hill chart of the Pelton hydraulic turbine models, by processing the data measured on the stand. In addition, the tools offered by the application such as: interface, menu, input data, numerical and graphical results, etc. are described.
Mathews, Alyssa
Emissions from the combustion of fossil fuels are a growing pollution concern throughout the global community, as they have been linked to numerous health issues. The freight transportation sector is a large source of these emissions and is expected to continue growing as globalization persists. Within the US, the expanding development of the natural gas industry is helping to support many industries and leading to increased transportation. The process of High Volume Hydraulic Fracturing (HVHF) is one of the newer advanced extraction techniques that is increasing natural gas and oil reserves dramatically within the US, however the technique is very resource intensive. HVHF requires large volumes of water and sand per well, which is primarily transported by trucks in rural areas. Trucks are also used to transport waste away from HVHF well sites. This study focused on the emissions generated from the transportation of HVHF materials to remote well sites, dispersion, and subsequent health impacts. The Geospatial Intermodal Freight Transport (GIFT) model was used in this analysis within ArcGIS to identify roadways with high volume traffic and emissions. High traffic road segments were used as emissions sources to determine the atmospheric dispersion of particulate matter using AERMOD, an EPA model that calculates geographic dispersion and concentrations of pollutants. Output from AERMOD was overlaid with census data to determine which communities may be impacted by increased emissions from HVHF transport. The anticipated number of mortalities within the impacted communities was calculated, and mortality rates from these additional emissions were computed to be 1 in 10 million people for a simulated truck fleet meeting stricter 2007 emission standards, representing a best case scenario. Mortality rates due to increased truck emissions from average, in-use vehicles, which represent a mixed age truck fleet, are expected to be higher (1 death per 341,000 people annually).
Su, M.; Zhang, Y. X.; Zhang, J. Y.; Hou, H. C.
2016-05-01
According to the basic parameters of 211-80 high specific speed mixed-flow pump, based on the quasi-three dimensional flow theory, the hydraulic design of impeller and its matching spaced guide vanes for high specific speed mixed flow pump was completed, in which the iterative calculation of S 1, S 2 stream surfaces was employed to obtain meridional flow fields and the point-by-point integration method was employed to draw blade camber lines. Blades are thickened as well as blade leading edges are smoothed in the conformal mapping surface. Subsequently the internal fields of the whole flow passage of the designed pump were simulated by using RANS equations with RNG k-ε two-equation turbulent model. The results show that, compared with the 211-80 model, the hydraulic efficiency of the designed pump at the optimal flow rate increases 9.1%. The hydraulic efficiency of designed pump in low flow rate condition (78% designed flow rate) increases 6.46%. The hydraulic efficiency in high flow rate areas increases obviously and there is no bad phenomenon of suddenly decrease of hydraulic efficiency in model pump. From the distributions of velocity and pressure fields, it can be seen that the flow in impeller is uniform and the increase of pressure is gentle. There are no obvious impact phenomenon on impeller inlet and obvious wake shedding vortex phenomenon from impeller outlet to guide vanes inlet.
The application of Excel in municipal drainage pipeline hydraulic calculation%Excel 在市政排水管道水力计算中的应用
Institute of Scientific and Technical Information of China (English)
赖江华
2015-01-01
介绍了排水管渠的水力计算公式，从雨水管道水力计算与污水管道水力计算两方面着手，探讨了运用Excel软件进行水力计算的方法，通过试算分析指出运用Excel软件进行水力计算简单便捷、精确度高。%This paper introduced the hydraulic calculation formula of drain ditch,from rainwater pipeline hydraulic calculation and sewage pipe-line hydraulic calculation two aspects,discussed the method using Excel software made hydraulic calculation,through the trial analysis indicated that using Excel software for hydraulic calculation was simple and convenient,had high precision.
Masuzawa, Toru; Ohta, Akiko; Tanaka, Nobuatu; Qian, Yi; Tsukiya, Tomonori
2009-01-01
The effect of the hydraulic force on magnetically levitated (maglev) pumps should be studied carefully to improve the suspension performance and the reliability of the pumps. A maglev centrifugal pump, developed at Ibaraki University, was modeled with 926 376 hexahedral elements for computational fluid dynamics (CFD) analyses. The pump has a fully open six-vane impeller with a diameter of 72.5 mm. A self-bearing motor suspends the impeller in the radial direction. The maximum pressure head and flow rate were 250 mmHg and 14 l/min, respectively. First, a steady-state analysis was performed using commercial code STAR-CD to confirm the model's suitability by comparing the results with the real pump performance. Second, transient analysis was performed to estimate the hydraulic force on the levitated impeller. The impeller was rotated in steps of 1 degrees using a sliding mesh. The force around the impeller was integrated at every step. The transient analysis revealed that the direction of the radial force changed dynamically as the vane's position changed relative to the outlet port during one circulation, and the magnitude of this force was about 1 N. The current maglev pump has sufficient performance to counteract this hydraulic force. Transient CFD analysis is not only useful for observing dynamic flow conditions in a centrifugal pump but is also effective for obtaining information about the levitation dynamics of a maglev pump.
Chiral nucleon-nucleon forces in nuclear structure calculations
Directory of Open Access Journals (Sweden)
Coraggio L.
2016-01-01
Full Text Available Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
Chiral nucleon-nucleon forces in nuclear structure calculations
Coraggio, L; Holt, J W; Itaco, N; Machleidt, R; Marcucci, L E; Sammarruca, F
2016-01-01
Realistic nuclear potentials, derived within chiral perturbation theory, are a major breakthrough in modern nuclear structure theory, since they provide a direct link between nuclear physics and its underlying theory, namely the QCD. As a matter of fact, chiral potentials are tailored on the low-energy regime of nuclear structure physics, and chiral perturbation theory provides on the same footing two-nucleon forces as well as many-body ones. This feature fits well with modern advances in ab-initio methods and realistic shell-model. Here, we will review recent nuclear structure calculations, based on realistic chiral potentials, for both finite nuclei and infinite nuclear matter.
Boehning, Fiete; Timms, Daniel L; Amaral, Felipe; Oliveira, Leonardo; Graefe, Roland; Hsu, Po-Lin; Schmitz-Rode, Thomas; Steinseifer, Ulrich
2011-08-01
In many state-of-the-art rotary blood pumps for long-term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design--singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (∼0 N), the circular volute yielded the highest force (∼2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study.
Energy Technology Data Exchange (ETDEWEB)
Proskuryakov, K.N.; Bogomazov, D.N.; Poliakov, N. [Moscow Power Engineering Institute (Technical University), Moscow (Russian Federation)
2007-07-01
The new special module to neutron-physic and thermal-hydraulic computer codes for coolant acoustical characteristics calculation is worked out. The Russian computer code Rainbow has been selected for joint use with a developed module. This code system provides the possibility of EFOCP (Eigen Frequencies of Oscillations of the Coolant Pressure) calculations in any coolant acoustical elements of primary circuits of NPP. EFOCP values have been calculated for transient and for stationary operating. The calculated results for nominal operating were compared with results of measured EFOCP. For example, this comparison was provided for the system: 'pressurizer + surge line' of a WWER-1000 reactor. The calculated result 0.58 Hz practically coincides with the result of measurement (0.6 Hz). The EFOCP variations in transients are also shown. The presented results are intended to be useful for NPP vibration-acoustical certification. There are no serious difficulties for using this module with other computer codes.
Directory of Open Access Journals (Sweden)
Egor M. Mikhailovsky
2015-06-01
Full Text Available We proposed a method for numerically solving the problem of flow distribution in hydraulic circuits with lumped parameters for the case of random closing relations. The conventional and unconventional types of relations for the laws of isothermal steady fluid flow through the individual hydraulic circuit components are studied. The unconventional relations are presented by those given implicitly by the flow rate and dependent on the pressure of the working fluid. In addition to the unconventional relations, the formal conditions of applicability were introduced. These conditions provide a unique solution to the flow distribution problem. A new modified nodal pressure method is suggested. The method is more versatile in terms of the closing relation form as compared to the unmodified one, and has lower computational costs as compared to the known technique of double-loop iteration. The paper presents an analysis of the new method and its algorithm, gives a calculated example of a gas transportation network, and its results.
Thermal-hydraulic Fortran program for steady-state calculations of plate-type fuel research reactors
Directory of Open Access Journals (Sweden)
Khedr Ahmed
2008-01-01
Full Text Available The safety assessment of research and power reactors is a continuous process covering their lifespan and requiring verified and validated codes. Power reactor codes all over the world are well established and qualified against real measuring data and qualified experimental facilities. These codes are usually sophisticated, require special skills and consume a lot of running time. On the other hand, most research reactor codes still require much more data for validation and qualification. It is, therefore, of benefit to any regulatory body to develop its own codes for the review and assessment of research reactors. The present paper introduces a simple, one-dimensional Fortran program called THDSN for steady-state thermal-hydraulic calculations of plate-type fuel research reactors. Besides calculating the fuel and coolant temperature distributions and pressure gradients in an average and hot channel, the program calculates the safety limits and margins against the critical phenomena encountered in research reactors, such as the onset of nucleate boiling, critical heat flux and flow instability. Well known thermal-hydraulic correlations for calculating the safety parameters and several formulas for the heat transfer coefficient have been used. The THDSN program was verified by comparing its results for 2 and 10 MW benchmark reactors with those published in IAEA publications and a good agreement was found. Also, the results of the program are compared with those published for other programs, such as the PARET and TERMIC.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
Transporting sediment is a natural function of the river. To maintain the normal evolution of the river certain amount of water flow is required, which is called the instream flow requirements for transporting sediment (IFRTS). We defined the permitting flow velocity by the conception of IFRTS, and also put forward the ecological hydraulic radius model (EHRM) to estimate IFRTS. The calculating process of EHRM is explained by the example of Daofu Hydrological Station on Xianshui branch of Yalong River in the west line first-stage construction of South-North Water Transfer Project. The result shows that the IFRTS occupied 29.7%―59.5% of annual mean discharge in flood season, the average of IFRTS was about 100.2 m3/s during 1966―1987, it is close to the IFRTS 90 m3/s calculated by IFRTS conception. Hence, it is feasible to use EHRM to calculate IFRTS.
Hydraulic System Design of Hydraulic Actuators for Large Butterfly Valves
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
Jeong, J.J.; Joo, H.G.; Cho, B.O.; Zee, S.Q.; Lee, W.J. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)
2001-07-01
To assess the performance of KAERI coupled multi-dimensional system thermal- hydraulics (T/H) and three-dimensional (3-D) kinetics code, MARS/MASTER, Exercise III of the OECD main steam line break benchmark problem is solved. The coupled code is capable of employing an individual flow channel for each fuel assembly as well as lumped ones. The basic analysis model of the reference plant consists of four major components: a 3-D core neutronics model, a 3-D thermal-hydraulic model for the reactor vessel employing lumped flow channels, a refined core T/H model and a 1-D T/H model for coolant system. Calculations were performed with and without the refined core T/H model. The results of the basic calculation performed without the refined core T/H model show that the core power distribution evolves to a highly localized shape due to the presence of a stuck rod, as well as asymmetric flow distribution in the reactor core. The results of the refined core T/H model indicate that the local peaking factor can be reduced by as much as 22 % through accurate representation of the local T/H feedback effects. Nonetheless, the global transient behaviors are not significantly affected. (author)
Shalaginova, Z. I.
2016-03-01
The mathematical model and calculation method of the thermal-hydraulic modes of heat points, based on the theory of hydraulic circuits, being developed at the Melentiev Energy Systems Institute are presented. The redundant circuit of the heat point was developed, in which all possible connecting circuits (CC) of the heat engineering equipment and the places of possible installation of control valve were inserted. It allows simulating the operating modes both at central heat points (CHP) and individual heat points (IHP). The configuration of the desired circuit is carried out automatically by removing the unnecessary links. The following circuits connecting the heating systems (HS) are considered: the dependent circuit (direct and through mixing elevator) and independent one (through the heater). The following connecting circuits of the load of hot water supply (HWS) were considered: open CC (direct water pumping from pipelines of heat networks) and a closed CC with connecting the HWS heaters on single-level (serial and parallel) and two-level (sequential and combined) circuits. The following connecting circuits of the ventilation systems (VS) were also considered: dependent circuit and independent one through a common heat exchanger with HS load. In the heat points, water temperature regulators for the hot water supply and ventilation and flow regulators for the heating system, as well as to the inlet as a whole, are possible. According to the accepted decomposition, the model of the heat point is an integral part of the overall heat-hydraulic model of the heat-supplying system having intermediate control stages (CHP and IHP), which allows to consider the operating modes of the heat networks of different levels connected with each other through CHP as well as connected through IHP of consumers with various connecting circuits of local systems of heat consumption: heating, ventilation and hot water supply. The model is implemented in the Angara data
First vapor explosion calculations performed with MC3D thermal-hydraulic code
Energy Technology Data Exchange (ETDEWEB)
Brayer, C.; Berthoud, G. [CEA Centre d`Etudes de Grenoble, 38 (France). Direction des Reacteurs Nucleaires
1998-01-01
This paper presents the first calculations performed with the `explosion` module of the multiphase computer code MC3D, which is devoted to the fine fragmentation and explosion phase of a fuel coolant interaction. A complete description of the physical laws included in this module is given. The fragmentation models, taking into account two fragmentation mechanisms, a thermal one and an hydrodynamic one, are also developed here. Results to some calculations to test the numerical behavior of MC3D and to test the explosion models in 1D or 2D are also presented. (author)
New method of calculating fuzzy reliability of hydraulic cylinder stability%液压缸稳定性模糊可靠度计算的新方法
Institute of Scientific and Technical Information of China (English)
龚相超; 胡百鸣; 韩芳
2011-01-01
There are many factors to influence the critical press of the hydraulic cylinder. The action mechanism is not entirely clear about how various parts of the hydraulic cylinder work on its stability, moreover, the load of the hydraulic cylinder is fuzzy and random. In the paper, the fuzzy reliability of the hydraulic cylinder stability is calculated according to mechanical fuzzy reliability theory, which provides an important reference for the design of the hydraulic cylinder. In addition, linear membership function is used for the critical pressure of the hydraulic cylinder, and the load is a kind of random variable which is normallydistributed. The calculation example shows that the method is effective.%根据机械模糊可靠性理论，笔者计算了液压缸稳定性的模糊可靠度，为液压缸设计提供了一个重要的参照指标。计算液压缸临界压力采用了线性隶属度函数，工作载荷为正态分布的随机变量，计算实例证明了该计算方法的有效性。
Calculating levitation forces in the magnet-high-temperature superconductor systems
Ermolaev, YS; Rudnev, IA
2005-01-01
A new method of calculation of the magnetic levitation force in the permanent magnet-high-temperature superconductor systems is proposed based on the Maxwell equations and the Bean model. The dependences of the levitation force on the gap width calculated for various regimes of superconductor coolin
Calculating levitation forces in the magnet-high-temperature superconductor systems
Ermolaev, YS; Rudnev, IA
2005-01-01
A new method of calculation of the magnetic levitation force in the permanent magnet-high-temperature superconductor systems is proposed based on the Maxwell equations and the Bean model. The dependences of the levitation force on the gap width calculated for various regimes of superconductor coolin
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.
Mooring Model Experiment and Mooring Line Force Calculation
Institute of Scientific and Technical Information of China (English)
向溢; 谭家华; 杨建民; 张承懿
2001-01-01
Mooring model experiment and mooring line tension determination are of significance to the design of mooring systems and berthing structures. This paper mainly involves: (a) description and analysis of a mooring model experiment;(b) derivation of static equilibrium equations for a moored ship subjected to wind, current and waves; (c) solution of mo.oring equations with the Monte Carlo method; (d) qualitative analysis of effects of pier piles on mooring line forces. Special emphasis is placed on the derivation ofstatic equilibrium equations, solution method and the mooring model experiment.
Energy Technology Data Exchange (ETDEWEB)
Jordan, K. A.; Schubring, D. [Univ. of Florida, Florida (United States); Girardin, G.; Pautz, A. [Swiss Federal Institute of Technology, Zuerich (Switzerland)
2013-07-01
A collaboration between the University of Florida and the Swiss Federal Institute of Technology, Lausanne (EPFL) has been formed to develop and validate detailed coupled multiphysics models of the zero-power (100 W) CROCUS reactor at EPFL and the 100 kW University of Florida Training Reactor, for the comprehensive analysis of the reactor behavior under transient (neutronic or thermal-hydraulic induced) conditions. These two reactors differ significantly in the core design and thermal power output, but share unique heat transfer and flow characteristics. They are characterized by single-phase laminar water flow at near-atmospheric pressures in complex geometries with the possibility of mechanically entrained air bubbles. Validation experiments will be designed to expand the validation domain of these existing models, computational codes and techniques. In this process, emphasis will be placed on validation of the coupled models developed to gain confidence in their applicability for safety analysis. EPFL is responsible for the design and implementation of transient experiments to generate a database of reactor parameters (flow distribution, power profile, and power evolution) to be used to validate against code predictions. The transient experiments performed at EPFL will be simulated on the basis of developed models for these tasks. Comparative analysis will be performed with SERPENT and MCNPX reference core models. UF focuses on the generation of the coupled neutron kinetics and thermal-hydraulic models, including implementation of a TRACE/PARCS reactor simulator model, a PARET model, and development of full-field computational fluid dynamics models (using OpenFOAM) for refined thermal-hydraulics physics treatments. In this subtask of the project, the aim is to verify by means of CFD the validity of TRACE predictions for near-atmospheric pressure water flow in the presence of mechanically entrained air bubbles. The scientific understanding of these multiphysics
Bobbert, Maarten F; Gómez Alvarez, Constanza B; van Weeren, P René; Roepstorff, Lars; Weishaupt, Michael A
2007-06-01
The purpose of this study was to determine whether individual limb forces could be calculated accurately from kinematics of trotting and walking horses. We collected kinematic data and measured vertical ground reaction forces on the individual limbs of seven Warmblood dressage horses, trotting at 3.4 m s(-1) and walking at 1.6 m s(-1) on a treadmill. First, using a segmental model, we calculated from kinematics the total ground reaction force vector and its moment arm relative to each of the hoofs. Second, for phases in which the body was supported by only two limbs, we calculated the individual reaction forces on these limbs. Third, we assumed that the distal limbs operated as linear springs, and determined their force-length relationships using calculated individual limb forces at trot. Finally, we calculated individual limb force-time histories from distal limb lengths. A good correspondence was obtained between calculated and measured individual limb forces. At trot, the average peak vertical reaction force on the forelimb was calculated to be 11.5+/-0.9 N kg(-1) and measured to be 11.7+/-0.9 N kg(-1), and for the hindlimb these values were 9.8+/-0.7 N kg(-1) and 10.0+/-0.6 N kg(-1), respectively. At walk, the average peak vertical reaction force on the forelimb was calculated to be 6.9+/-0.5 N kg(-1) and measured to be 7.1+/-0.3 N kg(-1), and for the hindlimb these values were 4.8+/-0.5 N kg(-1) and 4.7+/-0.3 N kg(-1), respectively. It was concluded that the proposed method of calculating individual limb reaction forces is sufficiently accurate to detect changes in loading reported in the literature for mild to moderate lameness at trot.
Tensile force correction calculation method for prestressed construction of tension structures
Institute of Scientific and Technical Information of China (English)
Xin ZHUO; Guo-fa ZHANG; Koichiro ISHIKAWA; Dao-an LOU
2008-01-01
Factors such as errors during the fabrication or construction of structural components and errors of calculation assumption or calculation methods,are very likely to cause serious deviation of many strings'actual prestressing forces from the designed values during tension structure construction or service period,and further to threaten the safety and reliability of the structure.Aiming at relatively large errors of the prestressing force of strings in a tension structure construction or service period,this paper proposes a new finite element method(FEM),the"tensile force correction calculation method".Based on the measured prestressing forces of the strings,this new method applies the structure from the zero prestressing force status approach to the measured prestressing force status for the first phase,and from the measured prestressing force status approach to the designed prestressing force status for the second phase.The construction tensile force correction value for each string can be obtained by multi-iteration with FEM.Using the results of calculation,the strings'tensile force correction by group and in batch will be methodic,simple and accurate.This new calculation method Can be applied to the prestressed correction construction simulation analysis for tension structures.
Calculating Free Energies Using Scaled-Force Molecular Dynamics Algorithm
Darve, Eric; Wilson, Micahel A.; Pohorille, Andrew
2000-01-01
One common objective of molecular simulations in chemistry and biology is to calculate the free energy difference between different states of the system of interest. Examples of problems that have such an objective are calculations of receptor-ligand or protein-drug interactions, associations of molecules in response to hydrophobic, and electrostatic interactions or partition of molecules between immiscible liquids. Another common objective is to describe evolution of the system towards a low energy (possibly the global minimum energy), 'native' state. Perhaps the best example of such a problem is folding of proteins or short RNA molecules. Both types of problems share the same difficulty. Often, different states of the system are separated by high energy barriers, which implies that transitions between these states are rare events. This, in turn, can greatly impede exploration of phase space. In some instances this can lead to 'quasi non-ergodicity', whereby a part of phase space is inaccessible on timescales of the simulation. A host of strategies has been developed to improve efficiency of sampling the phase space. For example, some Monte Carlo techniques involve large steps which move the system between low-energy regions in phase space without the need for sampling the configurations corresponding to energy barriers (J-walking). Most strategies, however, rely on modifying probabilities of sampling low and high-energy regions in phase space such that transitions between states of interest are encouraged. Perhaps the simplest implementation of this strategy is to increase the temperature of the system. This approach was successfully used to identify denaturation pathways in several proteins, but it is clearly not applicable to protein folding. It is also not a successful method for determining free energy differences. Finally, the approach is likely to fail for systems with co-existing phases, such as water-membrane systems, because it may lead to spontaneous
Meunier, F; Couvreur, V; Draye, X; Vanderborght, J; Javaux, M
2017-03-02
Predicting root water uptake and plant transpiration is crucial for managing plant irrigation and developing drought-tolerant root system ideotypes (i.e. ideal root systems). Today, three-dimensional structural functional models exist, which allows solving the water flow equation in the soil and in the root systems under transient conditions and in heterogeneous soils. Yet, these models rely on the full representation of the three-dimensional distribution of the root hydraulic properties, which is not always easy to access. Recently, new models able to represent this complex system without the full knowledge of the plant 3D hydraulic architecture and with a limited number of parameters have been developed. However, the estimation of the macroscopic parameters a priori still requires a numerical model and the knowledge of the full three-dimensional hydraulic architecture. The objective of this study is to provide analytical mathematical models to estimate the values of these parameters as a function of local plant general features, like the distance between laterals, the number of primaries or the ratio of radial to axial root conductances. Such functions would allow one to characterize the behaviour of a root system (as characterized by its macroscopic parameters) directly from averaged plant root traits, thereby opening new possibilities for developing quantitative ideotypes, by linking plant scale parameters to mean functional or structural properties. With its simple form, the proposed model offers the chance to perform sensitivity and optimization analyses as presented in this study.
Institute of Scientific and Technical Information of China (English)
LIU Xingjun; WANG Cuiping; Ikuo OHNUMA; Ryosuke KAINUMA; Kiyohito ISHIDA; CHEN Xiaohu
2005-01-01
Using Becker's method, we calculate the interfacial energy between two liquid phases in an immiscible system. Based on the Gibbs-Thomson equation, the force acting on the droplet towards the thermal center can be obtained by integrating the interfacial energy between the droplet and matrix liquid phase, which is related to both the radius of a droplet and the temperature gradient. In addition, the forces of gravitation and buoyancy also act on the droplet. The calculated results indicate that the resultant for these forces together mainly decides the microstructure morphology of the solidified alloy. The calculated results are in good agreement with the corresponding experimental results.
Dodge, W. G.
1968-01-01
Computer program determines the forced vibration in three dimensional space of a multiple degree of freedom beam type structural system. Provision is made for the longitudinal axis of the analytical model to change orientation at any point along its length. This program is used by industries in which structural design dynamic analyses are performed.
An improved method for calculating force distributions in moment-stiff timber connections
DEFF Research Database (Denmark)
Ormarsson, Sigurdur; Blond, Mette
2012-01-01
An improved method for calculating force distributions in moment-stiff metal dowel-type timber connections is presented, a method based on use of three-dimensional finite element simulations of timber connections subjected to moment action. The study that was carried out aimed at determining how...... the slip modulus varies with the angle between the direction of the dowel forces and the fibres in question, as well as how the orthotropic stiffness behaviour of the wood material affects the direction and the size of the forces. It was assumed that the force distribution generated by the moment action...... taking place strives to minimize the slip rotation between the separate members of a given timber connection. The results of modified hand calculations based on the finite element calculations carried out were found to differ appreciably from the results of conventional hand calculations....
Fan, Zheyong; Siro, Topi; Harju, Ari
2012-01-01
In this paper, we develop a highly efficient molecular dynamics code fully implemented on graphics processing units for thermal conductivity calculations using the Green-Kubo formula. We compare two different schemes for force evaluation, a previously used thread-scheme where a single thread is used for one particle and each thread calculates the total force for the corresponding particle, and a new block-scheme where a whole block is used for one particle and each thread in the block calcula...
Liu, H; Glöckle, W; Elster, Ch.
2002-01-01
The Faddeev equations for the three-body bound state are solved directly as thre e-dimensional integral equations without employing partial wave decomposition. Two-body forces of the Malfliet-Tjon type and simple spin independent genuine three-body forces are considered for the calculation of the three-body binding energy.
On the origin and the calculation of the force in electrostatic actuators
Jakoby, Bernhard
2016-07-01
This paper reviews fundamental ways to calculate the forces between charged electrodes as they appear, e.g., in electrostatic drives. In particular the consideration of the force acting on the surface charge layers on the electrodes, the principle of virtual displacement, and the Maxwell stress tensor are considered for two examples: a parallel plate capacitor and an electrostatic comb drive featuring interdigitated electrodes.
应用MATLAB进行燃气管网水力计算%Hydraulic Calculation of Gas Pipe Network with MATLAB
Institute of Scientific and Technical Information of China (English)
欧阳曙光
2011-01-01
A new method for hydraulic calculation of gas pipe network with MATLAB was proposed,and an example of calculation was given.The advantages of this method were discussed and analyzed,which showed that MATLAB was the useful tool of hydraulic calculation for engineers of gas engineering because it was easy to learn and use and was efficient to program.%本文提出了一种应用MATLAB进行燃气管网水力计算的方法,给出了一个计算实例,并对该方法的优越性进行了分析和讨论。最后指出MATLAB易学、易用,而且编程效率高,是燃气工程技术人员应用计算机进行燃气管网水力计算的理想工具。
Naumov, Vladimir S; Ignatov, Stanislav K
2017-08-01
The GROMOS 56ACARBO force field for the description of carbohydrates was modified for calculations of chitosan (poly-1,4-(N-acetyl)-β-D-glucopyranosamine-2) with protonated and non-protonated amino groups and its derivatives. Additional parameterization was developed on the basis of quantum chemical calculations. The modified force field (56ACARBO_CHT) allows performing the molecular dynamic calculations of chitosans with different degrees of protonation corresponding to various acidity of medium. Test calculations of the conformational transitions in the chitosan rings and polymeric chains as well as the chitosan nanocrystal dissolution demonstrate good agreement with experimental data. Graphical abstract The GROMOS 56ACARBO_CHT force field allows performing the molecular dynamic calculations of chitosans with different types of amio-group: free, protonated, substituted.
Institute of Scientific and Technical Information of China (English)
Ming-hui YU; Hong-yan WEI; Song-bai WU
2015-01-01
Bank erosion is a typical process of lateral channel migration, which is accompanied by vertical bed evolution. As a main sediment source, the failed bank soil may directly cause the increase of sediment concentration and considerable channel evolution in a short time. The paper presents an experimental study on non-cohesive and cohesive homogenous bank failure processes, influence of the failed bank soil on bank re-collapse, as well as the interaction between bank failure and near-bank bed evolution due to fluvial hydraulic force. A series of experiments were carried out in a 180° bend rectangular flume. The results reveal the iteration cycle between bank erosion and bed deformation: undercutting of the riverbank, slip failure of the submerged zone of the bank, as well as cantilever failure of the overhang, failed bank soil staying at bank toe temporarily or hydraulic transportation, exchange between the failed bank soil and bed material, bed material load being re-transported either as bed load or as suspended load, and bed deformation. Same as bank failure, the mixing of failed bank soil and bed material is more severe near the curved flow apex. Moreover, non-cohesive bank failure tends to occur near the water surface while cohesive bank failure near the bank toe. For non-cohesive dense (sandy) soil, the bank erosion amount and residual amount of failed bank soil on the bed increase with the near-bank velocity or bed erodibility. But for cohesive soil, only bank erosion amount follows the above rule. The results are expected to provide theoretical basis for river management and flood prevention.
Institute of Scientific and Technical Information of China (English)
王丽薇; 张亦工; 高殿荣
2011-01-01
结合锻造工况,建立80 MN快速锻造液压机主控系统物理模型,考虑到活动横梁两侧压力作用面积不同,将各工况等效为非对称缸驱动活动横梁运动,分别推导活动横梁两侧液压弹簧刚度以及各工况下等效质量,给出主控系统液压固有频率计算公式,最后以正弦锻造曲线作为理想位移曲线,校核负载稳定运行的最大速度和最大加速度值.结果表明,该液压机液压系统设计完全满足动态性能要求.%Based on forging conditions, the physical model of main control system for 80 MN high speed forging hydraulic press was build, considering the different pressure action areas in both sides of movable beam, all forging working conditions were equivalent to the movement of movable beam driven by unsymmetrical cylinder, the hydraulic spring stiffness in both sides of movable beam and equivalent mass with all working conditions were deduced respectively. Furthermore the calculation formulas for hydraulic inherent frequency of main control system were presented. The max speed and max acceleration under stable operation condition were checked using sine forging curve as ideal displacement curve. The results show that the hydraulic system design of hydraulic press satisfies requirements for dynamic performances.
Gamma-point lattice free energy estimates from O(1) force calculations
DEFF Research Database (Denmark)
Voss, Johannes; Vegge, Tejs
2008-01-01
We present a new method for estimating the vibrational free energy of crystal (and molecular) structures employing only a single force calculation, for a particularly displaced configuration, in addition to the calculation of the ground state configuration. This displacement vector is the sum...
Gamma-point lattice free energy estimates from O(1) force calculations
DEFF Research Database (Denmark)
Voss, Johannes; Vegge, Tejs
2008-01-01
We present a new method for estimating the vibrational free energy of crystal (and molecular) structures employing only a single force calculation, for a particularly displaced configuration, in addition to the calculation of the ground state configuration. This displacement vector is the sum...
Institute of Scientific and Technical Information of China (English)
李晶; 汤贵春; 曹骏飞; 是贤珠
2015-01-01
A thermodynamic analysis method was adopted to hydraulic servo steering units in temG perature controlling for reducing aircraft hydraulic systems failure.A hydraulic servo steering units can be simplified to a servo valve and an actuator cylinder.Based on the first law of thermodynamics, the thermodynamic model of hydraulic steering units for aircraft was established.And the thermodyG namic differential equations set of the model were derived with lumped parameter method,and solved by RungeKutta method.Simulations of hydraulic servo steering thermodynamics model were carried out by employing MATLAB software.And the calculation results coincide with the experimental data. The model presented herein can be used to calculate the dynamic temperature of aircraft hydraulic sysG tems.%为减少飞机液压系统故障，从温度控制层面对飞机液压伺服舵机进行热力学分析。将液压伺服舵机的物理模型简化为伺服阀控制作动筒的形式，建立液压伺服舵机热力学模型。根据热力学第一定律，采用集中参数法建立热力学方程。基于 MATLAB 平台，采用龙格库塔法对舵机热力学模型进行编程仿真计算，得出舵机各节点温度分布曲线。将仿真结果与实验数据进行了对比，对比结果验证了飞机液压伺服舵机热力学模型的正确性，该模型可应用于飞机液压系统动态温度计算。
An improved method for calculating force distributions in moment-stiff timber connections
DEFF Research Database (Denmark)
Ormarsson, Sigurdur; Blond, Mette
2012-01-01
An improved method for calculating force distributions in moment-stiff multi-dowel timber connections is presented, a method based on use of three-dimensional finite element simulations of timber connections subjected to moment action. The study that was carried out aimed at determining how...... the slip modulus varies with the angle between the direction of the dowel forces and the fibres in question, as well as how the orthotropic stiffness behaviour of the wood material affects the direction and the size of the forces. It was assumed that the force distribution generated by the moment action...... taking place strives to minimize the slip rotation between the separate members of a given timber connection. The results of modified hand calculations and of the corresponding finite element calculations that were performed were found to agree rather closely, and to differ remarkably from the results...
Institute of Scientific and Technical Information of China (English)
XU Zhongming; HUANG Ping
2007-01-01
A method based on the energy dissipation mechanism of an Independent Oscillator model is used to calculate the frictional force and the friction coefficient of interfacial friction. The friction work is calculated with considering the potential change of contact surfaces during sliding. The potential change can be gained by a universal adhesive energy function. The relationships between frictional force and parameters of a tribo-system, such as surface energy and microstructure of interfacial material, are set up. The calculation results of the known experimental data denote that the frictional force is nearly proportional to the surface energy of the material, nearly inversely proportional to the scaling length, and independent of the lattice constant. The results agree with that of adhesion friction equations. They also agree with the experimental results performed with an atomic-force microscope under the ultra high vacuum condition.
The Methodology of Calculation of Cutting Forces When Machining Composite Materials
Rychkov, D. A.; Yanyushkin, A. S.
2016-08-01
Cutting of composite materials has specific features and is different from the processing of metals. When this characteristic intense wear of the cutting tool. An important criterion in the selection process parameters composite processing is the value of the cutting forces, which depends on many factors and is determined experimentally, it is not always appropriate. The study developed a method of determining the cutting forces when machining composite materials and the comparative evaluation of the calculated and actual values of cutting forces. The methodology for calculating cutting forces into account specific features of the cutting tool and the extent of wear, the strength properties of the processed material and cutting conditions. Experimental studies conducted with fiberglass milling cutter equipped with elements of hard metal VK3M. The discrepancy between the estimated and the actual values of the cutting force is not more than 10%.
Milton, Kimball A; Wagner, Jef; Cavero-Pelaez, Ines
2009-01-01
Various applications of the multiple scattering technique to calculating Casimir energy are described. These include the interaction between dilute bodies of various sizes and shapes, temperature dependence, interactions with multilayered and corrugated bodies, and new examples of exactly solvable separable bodies.
Calculation of muscle forces during normal gait under consideration of femoral bending moments.
Lutz, Frederick; Mastel, Roland; Runge, Martin; Stief, Felix; Schmidt, André; Meurer, Andrea; Witte, Hartmut
2016-09-01
This paper introduces a new approach for computing lower extremity muscle forces by incorporating equations that consider "bone structure" and "prevention of bending by load reduction" into existing optimization algorithms. Lower extremity muscle and joint forces, during normal gait, were calculated and compared using two different optimization approaches. We added constraint equations that prevent femoral bending loads to an existing approach that considers "minimal total muscular force". Gait parameters such as kinematics, ground reaction forces, and surface electromyographic activation patterns were examined using standardized gait analysis. A subject-specific anatomic model of the lower extremities, obtained from magnetic resonance images of a healthy male, was used for the simulations. Finite element analysis was used to calculate femoral loads. The conventional method of calculating muscle forces leads to higher rates of femoral bending and structural stress than the new approach. Adding equations with structural subject-specific parameters in our new approach resulted in reduced femoral stress patterns. These findings show that our new approach improves the accuracy of femoral stress and strain simulations. Structural overloads caused by bending can be avoided during inverse calculation of muscle forces.
Hydraulic Calculation Method for the Fluid Delivery System of Centrifugal Pump%离心泵流体输送系统水力计算方法
Institute of Scientific and Technical Information of China (English)
徐宏斌
2001-01-01
简述离心泵和管路的特性，介绍离心泵流体输送管路系统的水力计算方法，以及如何确定泵的安装高度。%The characteristics of centrifugal pump and pipeline are brieflyelaborated. The hydraulic calculation method for fluid delivery pipeline system of centrifugal pump and the method of determining the pump installation height are introduced.
Analysis of The Clamping Force for 2D Electro-hydraulic Rotary Valve%2D电液转阀式换向阀阀芯卡紧力分析
Institute of Scientific and Technical Information of China (English)
童成伟; 阮健; 孔晨菁; 刘奎
2016-01-01
Introduces the working principle of 2D electro-hydraulic rotary valve, and puts forward a design scheme of 2D electro-ydraulic rotary valve.Based on the principle of gap flow and analysis of the radial clamping force of the spool of 2D electro-hydraulic rotary valve un-der eccentric conditions,the theoretical calculation formula of the clamping force of the spool is obtained.Using MATLAB software to draw the relationship of spool radial clamping force with eccentric angle and the angle of high and low pressure groove.%介绍了2D电液转阀式换向阀的工作原理，提出了一种2D电液转阀式换向阀的设计方案；应用缝隙流动原理，对2D电液转阀式换向阀阀芯在偏心情况下的径向卡紧力进行系统理论分析，得到阀芯液压卡紧力的理论计算公式；运用MATLAB软件进行数值计算，得出阀芯径向卡紧力与偏心角位置和高低压槽口夹角的关系。
Approximate Method of Calculating Forces on Rudder During Ship Sailing on a Shipping Route
Directory of Open Access Journals (Sweden)
K. Zelazny
2014-09-01
Full Text Available Service speed of a ship in real weather conditions is a basic design parameter. Forecasting of this speed at preliminary design stage is made difficult by the lack of simple but at the same accurate models of forces acting upon a ship sailing on a preset shipping route. The article presents a model for calculating forces and moment on plane rudder, useful for forecasting of ship service speed at preliminary stages of ship design.
Institute of Scientific and Technical Information of China (English)
侯秋丰; 吕强; 刘雪莱; 史浩峰
2016-01-01
The finite element model of Hydraulic release bearing is established to study the influence of the construction of clutch hydraulic release bearing cylinder on the pressing force of sealing ring ,and this model is used for analyzing the process of pressing into the hydraulic release bearing's sealing ring .The characteristic curve of the pressing force of sealing ring and the displacement is obtained .The model is validated by comparing the calculated and experimental result .Then u-sing the established model ,the influence of the bearing cylinder's construction and the sealing ring friction coefficient for the pressing force of seal ring is analyzed .The results show that the pressing force of sealing ring has a big fluctuation when it is just pressed ,then gradually reduces and tends to be stable .If the friction coefficient and the outer diameter of cylinder re-duce or the inner diameter of cylinder increases ,the pressing force of sealing ring would reduce effectively .The developed model and conclusions proposed are instructive for the design and structure optimization of clutch hydraulic release bearing .%为了研究离合器液压分离轴承缸体结构对密封圈压入力的影响,建立了液压分离轴承有限元模型,对液压分离轴承密封圈压入过程进行了分析,得到了密封圈压入力随位移变化的关系曲线,并与相关试验结果进行对比分析,验证了有限元模型的正确性.利用建立的模型,分析了轴承缸体结构参数以及与密封圈摩擦因数对压入力的影响.结果表明,在刚被压入时,密封圈受到的压入力波动较大,随后逐渐减小并趋于稳定.降低摩擦因数,增大缸体的内径和降低缸体外径可以有效地降低密封圈受到的压入力.该建模方法和结论对液压分离轴承的设计和结构优化具有一定的指导意义.
Adaptive GPU-accelerated force calculation for interactive rigid molecular docking using haptics.
Iakovou, Georgios; Hayward, Steven; Laycock, Stephen D
2015-09-01
Molecular docking systems model and simulate in silico the interactions of intermolecular binding. Haptics-assisted docking enables the user to interact with the simulation via their sense of touch but a stringent time constraint on the computation of forces is imposed due to the sensitivity of the human haptic system. To simulate high fidelity smooth and stable feedback the haptic feedback loop should run at rates of 500Hz to 1kHz. We present an adaptive force calculation approach that can be executed in parallel on a wide range of Graphics Processing Units (GPUs) for interactive haptics-assisted docking with wider applicability to molecular simulations. Prior to the interactive session either a regular grid or an octree is selected according to the available GPU memory to determine the set of interatomic interactions within a cutoff distance. The total force is then calculated from this set. The approach can achieve force updates in less than 2ms for molecular structures comprising hundreds of thousands of atoms each, with performance improvements of up to 90 times the speed of current CPU-based force calculation approaches used in interactive docking. Furthermore, it overcomes several computational limitations of previous approaches such as pre-computed force grids, and could potentially be used to model receptor flexibility at haptic refresh rates.
Directory of Open Access Journals (Sweden)
MohammadReza Zare
2010-12-01
Full Text Available In permanent magnet (PM linear motor, there is force ripple, which is detrimental to positioning. This force ripple is mainly due to cogging force and mutual force ripple. These forces are affected by geometric parameters of brushless PM motor, such as width of magnet, height of magnet, shifted length of magnet pole, length and height of armature and slot width. If flux density distribution can be described by geometric parameters that are related to the force ripple and force ripple is described by the flux density distribution, the optimal design can be done by considering force ripple as cost function and geometric parameters as design variables. In this paper, at first, flux density distribution in the air gap is calculated by analytic solution of Laplace and Possion equations in the function of geometric parameters. Cogging force is obtained by integrating Maxwell stress tensor, which is described by flux density distribution, on slot face and end face of iron core of armature. Secondly, a finite element method is presented in order to compare the previous method with this method.
Evaluation of carbohydrate molecular mechanical force fields by quantum mechanical calculations
DEFF Research Database (Denmark)
Hemmingsen, Lars Bo Stegeager; Madsen, D.E.; Esbensen, A.L.
2004-01-01
A quantitative evaluation of 20 second-generation carbohydrate force fields was carried out using ab initio and density functional methods. Geometry-optimized structures (B3LYP/6-31G(d)) and relative energies using augmented correlation consistent basis sets were calculated in gas phase...... for monosaccharide carbohydrate benchmark systems. Selected results are: (i) The interaction energy of the alpha-D-alucopyranose-H2O heterodimer is estimated to be 4.9 kcal/mol, using a composite method including terms at highly correlated (CCSD(T)) level. Most molecular mechanics force fields are in error......-generation carbohydrate force fields. No single force field is consistently better than the others for all the test cases. A statistical assessment of the performance of the force fields indicates that CHEAT(95), CFF, certain versions of Amber and of MM3 have the best overall performance, for these gas phase...
Prying Force Calculation and Design Method for T-shaped Tensile Connector with High Strength Bolt
Institute of Scientific and Technical Information of China (English)
Zhaoxin Hou; Guohong Huang; Chao Gong
2015-01-01
In order to establish the design method for T⁃shaped tensile connector with high strength bolt, the theoretical analysis is carried out. Firstly, it analyzes the performance of the connector and establishes prying force calculation model. Based on the model, prying force equation and function between bolt prying force and flange thickness is derived, and the min and max thickness requirement of flange plate under a certain tension load is then obtained. Finally, two simplified design methods of the connector are proposed, which are bolt pulling capacity method and flange plate bending capacity method.
Habegger, Maria L; Motta, Philip J; Huber, Daniel R; Dean, Mason N
2012-12-01
Evaluations of bite force, either measured directly or calculated theoretically, have been used to investigate the maximum feeding performance of a wide variety of vertebrates. However, bite force studies of fishes have focused primarily on small species due to the intractable nature of large apex predators. More massive muscles can generate higher forces and many of these fishes attain immense sizes; it is unclear how much of their biting performance is driven purely by dramatic ontogenetic increases in body size versus size-specific selection for enhanced feeding performance. In this study, we investigated biting performance and feeding biomechanics of immature and mature individuals from an ontogenetic series of an apex predator, the bull shark, Carcharhinus leucas (73-285cm total length). Theoretical bite force ranged from 36 to 2128N at the most anterior bite point, and 170 to 5914N at the most posterior bite point over the ontogenetic series. Scaling patterns differed among the two age groups investigated; immature bull shark bite force scaled with positive allometry, whereas adult bite force scaled isometrically. When the bite force of C. leucas was compared to those of 12 other cartilaginous fishes, bull sharks presented the highest mass-specific bite force, greater than that of the white shark or the great hammerhead shark. A phylogenetic independent contrast analysis of anatomical and dietary variables as determinants of bite force in these 13 species indicated that the evolution of large adult bite forces in cartilaginous fishes is linked predominantly to the evolution of large body size. Multiple regressions based on mass-specific standardized contrasts suggest that the evolution of high bite forces in Chondrichthyes is further correlated with hypertrophication of the jaw adductors, increased leverage for anterior biting, and widening of the head. Lastly, we discuss the ecological significance of positive allometry in bite force as a possible
Calculation and Analysis of Internal Force in Arch Structure of Frozen Soil
Institute of Scientific and Technical Information of China (English)
YUE Feng-tian; ZHANG Yong; SHI Rong-jian
2005-01-01
Aimed at the frozen soil arch reinforcement form of upside shed used for the shield machine launching in tunneling the internal force of the structure was calculated with the aid of the structural mechanics theory. Considering the space characteristics of the structure,this calculating method is suitable for practical engineering.Moreover,the behavior of the freezing arch reinforcement structure was analyzed combined with an engineering case.
液压冲击的分析计算及减小措施%Analysis and Calculation of Hydraulic Impact and its Reduction Measures
Institute of Scientific and Technical Information of China (English)
徐成东
2016-01-01
从液压冲击发生的机理出发，提出造成液压冲击的两大因素是管道阀门突然关闭和运动部件迅速制动或换向，并对其分别进行了详细的分析和计算，提出了具体的减小措施。%Based on the occurrence mechanism of hydraulic impact , it is put forward that two causes of hydraulic impact are sudden closing of the pipeline valve and quick braking or reversing of the moving part .Detailed analysis and calculation have been performed respectively and specific reduction measures have been proposed .
Energy Technology Data Exchange (ETDEWEB)
Kim, Chang Hyun; Kim, Young Ae; Oh, Seung Jong; Park, Jong Woon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)
2007-10-15
The increase of the acceptance tolerance of Pressurizer Safety Valve (PSV) test is vital for the safe operation of nuclear power plants because the frequent tests may make the valves decrepit and become a cause of leak. Recently, Korea Hydro and Nuclear Power Company (KHNP) is building a PSV performance test facility to provide the technical background data for the relaxation of the acceptance tolerance of PSV including the valve pop-up characteristics and the loop seal dynamics (if the plant has the loop seal in the upstream of PSV). The discharge piping and supports must be designed to withstand severe transient hydrodynamic loads when the safety valve actuates. The evaluation of hydrodynamic loads is a two-step process: first the thermal hydraulic behavior in the piping must be defined, and then the hydrodynamic loads are calculated from the thermal hydraulic parameters such as pressure and mass flow. The hydrodynamic loads are used as input to the structural analysis.
Highly eccentric inspirals into a Schwarzschild black hole using self-force calculations
Osburn, Thomas; Warburton, Niels; Evans, Charles
2016-03-01
Eccentric-orbit inspirals into a massive black hole are calculated using the gravitational self-force. Both extreme-mass-ratio inspirals (EMRIs) and intermediate-mass-ratio inspirals (IMRIs) are modeled. These calculations include all dissipative and conservative first-order-in-the-mass-ratio effects for inspirals into a Schwarzschild black hole. We compute systems with initial eccentricities as high as e = 0.8 and initial separations as large as 100 M. In the case of EMRIs, the calculations follow the decay through many thousands of orbits up to the onset of the plunge. Inspirals are computed using an osculating-orbits scheme that is driven by self-force data from a hybridized self-force code. A Lorenz gauge self-force code is combined with highly accurate flux data from a Regge-Wheeler-Zerilli code, allowing the hybrid self-force model to track orbital phase in the inspirals to within 0.1 radians or better. Extensions of the method to include other physical effects are considered.
Analytical calculation of the drag force near drag crisis of a falling sphere
Assis, Armando V D B; Branco, N S
2010-01-01
We obtain analitically the $v^2$ dependence of the drag force on a falling sphere close to the drag crisis, as well as the drag coefficient at the drag crisis, with excellent agreement with experiment. We take into account the effects of viscosity in creating a turbulent boundary layer and perform the calculations using the Navier-Stokes equation.
Calculation method of ship collision force on bridge using artificial neural network
Institute of Scientific and Technical Information of China (English)
Wei FAN; Wan-cheng YUAN; Qi-wu FAN
2008-01-01
Ship collision on bridge is a dynamic process featured by high nonlinearity and instantaneity. Calculating ship-bridge collision force typically involves either the use of design-specification-stipulated equivalent static load, or the use of finite element method (FEM) which is more time-consuming and requires supercomputing resources. In this paper, we proposed an alternative approach that combines FEM with artificial neural network (ANN). The radial basis function neural network (RBFNN) employed for calculating the impact force in consideration of ship-bridge collision mechanics. With ship velocity and mass as the input vectors and ship collision force as the output vector, the neural networks for different network parameters are trained by the learning samples obtained from finite element simulation results. The error analyses of the learning and testing samples show that the proposed RBFNN is accurate enough to calculate ship-bridge collision force. The input-output relationship obtained by the RBFNN is essentially consistent with the typical empirical formulae. Finally, a special toolbox is developed for calculation efficiency in application using MATLAB software.
Use of pressure insoles to calculate the complete ground reaction forces
Forner Cordero, A.; Koopman, H.F.J.M.; Helm, van der F.C.T.
2004-01-01
A method to calculate the complete ground reaction force (GRF) components from the vertical GRF measured with pressure insoles is presented and validated. With this approach it is possible to measure several consecutive steps without any constraint on foot placement and compute a standard inverse dy
A Benchmark Calculation for the Nd Scattering with a Model Three-Body Force
Phyu, Aye Mya; Golak, Jacek; Oo, Htun Htun; Witala, Henryk; Gloeckle, Walter
2012-01-01
Using the complex energy method, the problem of nucleon-deuteron scattering is solved with a simple three-body force having a separable form. Our results are compared with the results of modern direct two-variable calculations and a good agreement is found. This forms a firm base for other applications of the complex energy method.
Du, Di; Toffoletto, Frank; Biswal, Sibani Lisa
2014-04-01
Typically the force between paramagnetic particles in a uniform magnetic field is described using the dipolar model, which is inaccurate when particles are in close proximity to each other. Instead, the exact force between paramagnetic particles can be determined by solving a three-dimensional Laplace's equation for magnetostatics under specified boundary conditions and calculating the Maxwell stress tensor. The analytical solution to this multi-boundary-condition Laplace's equation can be obtained by using a solid harmonics expansion in conjunction with the Hobson formula. However, for a multibody system, finite truncation of the Hobson formula does not lead to convergence of the expansion at all points, which makes the approximation physically unrealistic. Here we present a numerical method for solving this Laplace's equation for magnetostatics. This method uses a smoothed representation to replace all the boundary conditions. A two-step propagation is used to dramatically accelerate the calculation without losing accuracy. Using this method, we calculate the force between two paramagnetic particles in a uniform and a rotational external field and compare our results with other models. Furthermore, the many-body effects for three-particle, ten-particle, and 24-particle systems are examined using the same method. We also calculate the interaction between particles with different magnetic susceptibilities and particle diameters. The Laplace's equation solver method described in this article that is used to determine the force between paramagnetic particles is shown to be very useful for dynamic simulations for both two-particle systems and a large cluster of particles.
2D finite element analysis and force calculations for induction motors with broken bars
Directory of Open Access Journals (Sweden)
Hanafy Hassan Hanafy
2014-06-01
Full Text Available In this paper an ABC transient model of the three phase induction motor is developed that depends on self- and mutual inductance calculations based on accurate finite element analysis (FEA. This model can represent both healthy and broken bars’ conditions. The effects of that type of fault on the stator current, rotor bar currents distribution, the forces exerted on the rotor bars, the motor speed and motor torque are studied. It was observed that broken bar faults will cause fluctuations in the stator peak current and in the motor speed and torque. It was found that the asymmetry in the rotor bar currents will lead to asymmetrical distribution of the radial and tangential forces affecting the bars. The asymmetry in the tangential forces causes the fluctuations in the motor torque, while the asymmetry in the radial forces will increase the mechanical stresses on the rotor shaft.
Brueckner-Hartree-Fock calculations for finite nuclei with renormalized realistic forces
Hu, B. S.; Xu, F. R.; Wu, Q.; Ma, Y. Z.; Sun, Z. H.
2017-03-01
One can adopt two-step G -matrix approximations for the Brueckner-Hartree-Fock (BHF) calculations. The first G matrix is to soften the bare force, and the second one is to include the high-order correlations of the interaction in medium. The first G -matrix calculation for two-nucleon interaction should be done in the center-of-mass coordinate. As another alternative BHF approach, we have adopted the Vlow-k technique to soften the interaction and used the G matrix to include high-order correlations. The Vlow-k renormalization leads to high-momentum and low-momentum components of the interaction decoupled. With the Vlow-k potential, we have performed the BHF calculations for finite nuclei. The G -matrix elements with exact Pauli exclusions are calculated in the self-consistent BHF basis. To see effects from further possible correlations beyond BHF, we have simultaneously performed renormalized BHF (RBHF) calculations with the same potential. In RBHF, the mean field derived from realistic forces is modified by introducing the particle-occupation depletion resulting from many-body correlations. The ground-state energies and radii of the closed-shell nuclei, 4He, 16O, and 40Ca, have been investigated. The convergences of the BHF and RBHF calculations have been discussed and compared with other ab initio calculations with the same potential.
Ab initio MO calculation of force constants and dipole derivatives for formamide
Sugawara, Yoko; Hamada, Yoshiaki; Hirakawa, Akiko Y.; Tsuboi, Masamichi; Kato, Shigeki; Morokuma, Keiji
1980-08-01
Ab initio SCF MO calculations have been carried out for the equilibrium geometry, vibrational frequencies, force constants, dipole moment and its derivatives of formamide. The energy gradient method was employed and the 4-31G basis set was used. For in-plane vibrations: (1) Calculated normal frequencies were 10-20% greater than the observed fundamental frequencies. (2) Isotope shifts (- d0, - d1, - d2, and - d3 species) were well reproduced. (3) The calculated dipole moment derivatives showed a good correspondence with the infrared intensity pattern. (4) The NH 2 rocking—OCN bending cross term, which should be zero in the Urey—Bradley force field, came out to be as large as -0.18 mdyne A. For out-of-plane vibrations, especially for the NH 2 wagging, it was found to be essential to include polarization functions for N, C and O atoms.
A fast high-order method to calculate wakefield forces in an electron beam
Qiang, Ji; Ryne, Robert D
2012-01-01
In this paper we report on a high-order fast method to numerically calculate wakefield forces in an electron beam given a wake function model. This method is based on a Newton-Cotes quadrature rule for integral approximation and an FFT method for discrete summation that results in an $O(Nlog(N))$ computational cost, where $N$ is the number of grid points. Using the Simpson quadrature rule with an accuracy of $O(h^4)$, where $h$ is the grid size, we present numerical calculation of the wakefields from a resonator wake function model and from a one-dimensional coherent synchrotron radiation (CSR) wake model. Besides the fast speed and high numerical accuracy, the calculation using the direct line density instead of the first derivative of the line density avoids numerical filtering of the electron density function for computing the CSR wakefield force.
Osburn, Thomas; Evans, Charles; Hopper, Seth
2014-01-01
We present an algorithm for calculating the metric perturbations and gravitational self-force for extreme-mass-ratio inspirals (EMRIs) with eccentric orbits. The massive black hole is taken to be Schwarzschild and metric perturbations are computed in Lorenz gauge. The perturbation equations are solved as coupled systems of ordinary differential equations in the frequency domain. Accurate local behavior of the metric is attained through use of the method of extended homogeneous solutions and mode-sum regularization is used to find the self-force. We focus on calculating the self-force with sufficient accuracy to ensure its error contributions to the phase in a long term orbital evolution will be $\\delta\\Phi \\lesssim 10^{-2}$ radians. This requires the orbit-averaged force to have fractional errors $\\lesssim 10^{-8}$ and the oscillatory part of the self-force to have errors $\\lesssim 10^{-3}$ (a level frequently easily exceeded). Our code meets this error requirement in the oscillatory part, extending the reach...
图算角变力矩法%Chart Calculation Angular Change Force Moment Method
Institute of Scientific and Technical Information of China (English)
马楠
2012-01-01
The method of moment distribution is one kind of the mechanics analytical method with wide-ranging application in the engineering field. Angular change force moment is defined as the amount of the angular displacement of the structure joints expressed by force moment. Chart calculation angular change force moment method is defined as the method of solving the hyperstatic structure with the help of the concepts of the method of moment distribution. Its unknown amount is the angular change force moment and its object is the calculation chart. This is also the calculation while looking at the calculation chart. Chart calculation angular change force moment method is against the demerits such as the many waiting-for calculation amounts and the progressive calculation and the approximation with the error of truncation and so on in the method of moment distribution. Of course,it also externalized the merits such as the normalizing-calculation modality and the clear thought way and the reduced mind labour conveniently. Thus it has been one kind of the direct and accurate mechanics analytic method that has been the foundation of hyperstatic structure in order to build a common and unified mechanics analytic method.%力矩分配法,是工程界常用的手算结构的力学分析方法.以力矩表达结构结点角位移的量,称为角变力矩.以角变力矩为未知量,以计算图为对象利用力矩分配法概念求解超静定结构的方法,称为图算角变力矩法,即边看图边计算角变力矩的方法.图算角变力矩法,克服了力矩分配法直接待求量个数多、计算的渐近性和有截断误差的近似性等缺点,发扬了力矩分配法计算程式规范,省脑力、思路清晰等优点,成为一种直接精确的力学分析方法,为建立超静定结构普遍统一的力学分析方法奠定了基础.
Efficient Computation of Power, Force, and Torque in BEM Scattering Calculations
Reid, M T Homer
2013-01-01
We present concise, computationally efficient formulas for several quantities of interest -- including absorbed and scattered power, optical force (radiation pressure), and torque -- in scattering calculations performed using the boundary-element method (BEM) [also known as the method of moments (MOM)]. Our formulas compute the quantities of interest \\textit{directly} from the BEM surface currents with no need ever to compute the scattered electromagnetic fields. We derive our new formulas and demonstrate their effectiveness by computing power, force, and torque in a number of example geometries. Free, open-source software implementations of our formulas are available for download online.
Calculations of three-nucleon reactions with N3LO chiral forces: achievements and challenges
Witala, Henryk; Skibinski, Roman; Topolnicki, Kacper
2013-01-01
We discuss the application of the chiral N3LO forces to three-nucleon reactions and point to the challenges which will have to be addressed. Present approaches to solve three-nucleon Faddeev equations are based on a partial-wave decomposition. A rapid increase of the number of terms contributing to the chiral three-nucleon force when increasing the order of the chiral expansion from N2LO to N3LO forced us to develop a fast and effective method of automatized partial wave decomposition. At low energies of the incoming nucleon below about 20MeV, where only a limited number of partial waves is required, this method allowed us to perform calculations of reactions in the three-nucleon continuum using N3LO two- and three-nucleon forces. It turns out that inclusion of consistent chiral interactions, with relativistic 1/m corrections and short-range 2pi-contact term omitted in the N3LO three-nucleon force, does not explain the long standing low energy Ay-puzzle. We discuss problems arising when chiral forces are appl...
Robin, M. J. L.; Sudicky, E. A.; Gillham, R. W.; Kachanoski, R. G.
1991-10-01
Distribution coefficients (Kd), defined as the ratio of the concentration of solute associated with the solids to the concentration in solution, are widely used in the prediction of reactive solute transport. With the advent of stochastic approaches to describe solute transport, there is a need to examine the spatial distribution of Kd, and its correlation with the hydraulic conductivity (K). Distribution coefficients were measured in triplicates for strontium on 1279 subsamples of cores from Canadian Forces Base Borden for which K measurements were available. The Kd values ranged from 4.4 to 29.8 mL/g, with a mean of 9.9 and standard deviation of 2.89 mL/g. The standard error on the triplicate means was 0.95 mL/g or approximately 10% of the mean. The spatial behavior of Kd and K (expressed as In (Kd) and ln (K)) was examined in three directions: horizontally along two orthogonal transects and vertically. The two variables each behaved nearly identically in the two horizontal directions, suggesting horizontal isotropy. Horizontally, ln (Kd) appeared as "white noise" suggesting that the horizontal spacing between cores (1 m) was too large to detect any self-correlation. The distribution coefficient displayed increasing power spectral density with increasing scale in the vertical direction, while In (K) showed these trends in all directions. Depending on the model used, the, correlation lengths obtained by least squares fits of the power spectra varied from 1 to 7.5 m horizontally and from 10 to 30 cm vertically for ln (K); and from 30 cm to 2 m horizontally and from 30 to 70 cm vertically for ln (Kd). The ln (Kd) values showed a significant but very weak negative overall correlation with ln (K) at the 99.95% confidence level. The cross-spectral and coherency analysis showed that the sign and degree of correlation between ln (Kd) and ln (K) depended on the scale and direction considered. The correlations in all directions and at all scales were weak, and could not
Self-gravitational Force Calculation of Infinitesimally Thin Gaseous Disks on Nested Grids
Wang, Hsiang-Hsu; Taam, Ronald E.; Yen, David C. C.
2016-06-01
We extend the work of Yen et al. and develop second-order formulae to accommodate a nested grid discretization for the direct self-gravitational force calculation for infinitesimally thin gaseous disks. This approach uses a two-dimensional kernel that is derived for infinitesimally thin disks and is free of artificial boundary conditions. The self-gravitational force calculation is presented in generalized convolution forms for a nested grid configuration. A numerical technique derived from a fast Fourier transform is employed to reduce the computational complexity to be nearly linear. By comparing with analytic potential-density pairs associated with the generalized Maclaurin disks, the extended approach is verified to be of second-order accuracy when using numerical simulations. The proposed method is accurate, computationally fast, and has the potential to be applied to studies of planetary migration and the gaseous morphology of disk galaxies.
Self-Gravitational Force Calculation of Infinitesimally Thin Gaseous Disks on Nested Grids
Wang, Hsiang-Hsu; Yen, David C C
2016-01-01
We extend the work of Yen et al. (2012) and develop 2nd order formulae to accommodate a nested grid discretization for the direct self-gravitational force calculation for infinitesimally thin gaseous disks. This approach uses a two-dimensional kernel derived for infinitesimally thin disks and is free of artificial boundary conditions. The self-gravitational force calculation is presented in generalized convolution forms for a nested grid configuration. A numerical technique derived from a fast Fourier transform is employed to reduce the computational complexity to be nearly linear. By comparing with analytic potential-density pairs associated with the generalized Maclaurin disks, the extended approach is verified to be of second order accuracy using numerical simulations. The proposed method is accurate, computationally fast and has the potential to be applied to the studies of planetary migration and the gaseous morphology of disk galaxies.
A Force-Based Grid Manipulator for ALE Calculations in a Lobe Pump
Institute of Scientific and Technical Information of China (English)
John Vande Voorde; Jan Vierendeels; Erik Dick
2003-01-01
In this paper, a time-dependant calculation of flow in a lobe pump is presented. Calculations are performed using the arbitrary Lagrangean Eulerean (ALE) method. A grid manipulator is needed to move the nodes between time steps. The used grid manipulator is based on the pseudo-force idea. This means that each node is fictitiously connected with its 8 neighbours via fictitious springs. The equilibrium of the resulting pseudo spring forces defines the altered position of the nodes. The grid manipulator was coupled with a commercial flow solver and the whole was tested on the flow through a three-lobe lobe pump. Results were obtained for a rotational speed of 460 rpm and incompressible silicon oil as fluid.
Advanced model for the calculation of meshing forces in spur gear planetary transmissions
Iglesias Santamaría, Miguel; Fernández del Rincón, Alfonso; Juan de Luna, Ana Magdalena de; Díez Ibarbia, Alberto; García Fernández, Pablo; Viadero Rueda, Fernando
2015-01-01
This paper presents a planar spur gear planetary transmission model, describing in great detail aspects such as the geometric definition of geometric overlaps and the contact forces calculation, thus facilitating the reproducibility of results by fellow researchers. The planetary model is based on a mesh model already used by the authors in the study of external gear ordinary transmissions. The model has been improved and extended to allow for the internal meshing simulation, taking into cons...
Methodes de calcul des forces aerodynamiques pour les etudes des interactions aeroservoelastiques
Biskri, Djallel Eddine
L'aeroservoelasticite est un domaine ou interagissent la structure flexible d'un avion, l'aerodynamique et la commande de vol. De son cote, la commande du vol considere l'avion comme une structure rigide et etudie l'influence du systeme de commande sur la dynamique de vol. Dans cette these, nous avons code trois nouvelles methodes d'approximation de forces aerodynamiques: Moindres carres corriges, Etat minimal corrige et Etats combines. Dans les deux premieres methodes, les erreurs d'approximation entre les forces aerodynamiques approximees par les methodes classiques et celles obtenues par les nouvelles methodes ont les memes formes analytiques que celles des forces aerodynamiques calculees par LS ou MS. Quant a la troisieme methode, celle-ci combine les formulations des forces approximees avec les methodes standards LS et MS. Les vitesses et frequences de battement et les temps d'executions calcules par les nouvelles methodes versus ceux calcules par les methodes classiques ont ete analyses.
Are Time-Domain Self-Force Calculations Contaminated by Jost Solutions?
Jaramillo, Jose Luis; Canizares, Priscilla
2011-01-01
The modeling of the gravitational-wave emission from extreme-mass-ratio inspirals is crucial for their detection and analysis with the future space-based observatory LISA. The inspiral can be described as the action of a local force, the self-force, determined by the gravitational perturbations created by the small object, described as a point mass, on the background geometry. The calculation of the self-force is a challenging task that requires the control of sources of error such as spurious modes or numerical noise. Here we address the question of the possible emergence of a persistent spurious solution in time-domain schemes, referred to as a Jost junk solution in the literature, that may contaminate self-force calculations. Previous studies suggested that Jost solutions are due to the use of zero initial data, which is inconsistent with the singular sources associated with the point mass. However, in this work we show that the specific origin is an inconsistency in the translation of the singular sources...
Directory of Open Access Journals (Sweden)
Yu.S. Nagornov
2016-03-01
Full Text Available The present work is devoted to the analysis of three-dimensional data of atomic force microscopy for research of the morphology of red blood cells. In this paper we built a biomechanical model of the erythrocyte, which allowed calculating the intracellular pressure of erythrocyte based on data of atomic force microscopy. As a result, we obtained the dependence intracellular pressure on the morphology of red blood cell. We have proposed a method of estimating of intracellular pressure of erythrocytes based on numerical modeling and data of atomic force microscopy of erythrocytes scan, which involves a comparison of the experimental data with the results of numerical calculation. The method is applied to the data of atomic force microscopy of erythrocytes of experimental animals - dwarf domestic pigs with different degrees of obstructive jaundice and normal. It is shown that with increasing severity of the disease and the concentration of bilirubin in the blood there is an infringement erythrocyte membranes, by an average increasing their volume and intracellular pressure.
Wesseling, Mariska; de Groote, Friedl; Jonkers, Ilse
2014-01-22
This study examined the effect of body segment parameter (BSP) perturbations on joint moments calculated using an inverse dynamics procedure and muscle forces calculated using computed muscle control (CMC) during gait. BSP (i.e. segment mass, center of mass location (com) and inertia tensor) of the left thigh, shank and foot of a scaled musculoskeletal model were perturbed. These perturbations started from their nominal value and were adjusted to ±40% in steps of 10%, for both individual as well as combined perturbations in BSP. For all perturbations, an inverse dynamics procedure calculated the ankle, knee and hip moments based on an identical inverse kinematics solution. Furthermore, the effect of applying a residual reduction algorithm (RRA) was investigated. Muscle excitations and resulting muscle forces were calculated using CMC. The results show only a limited effect of an individual parameter perturbation on the calculated moments, where the largest effect is found when perturbing the shank com (MS(com,shank), the ratio of absolute difference in torque and relative parameter perturbation, is maximally -7.81 N m for hip flexion moment). The additional influence of perturbing two parameters simultaneously is small (MS(mass+com,thigh) is maximally 15.2 N m for hip flexion moment). RRA made small changes to the model to increase the dynamic consistency of the simulation (after RRA MS(com,shank) is maximally 5.01 N m). CMC results show large differences in muscle forces when BSP are perturbed. These result from the underlying forward integration of the dynamic equations.
Calculating forces on thin flat plates with incomplete vorticity-field data
Limacher, Eric; Morton, Chris; Wood, David
2016-11-01
Optical experimental techniques such as particle image velocimetry (PIV) permit detailed quantification of velocities in the wakes of bluff bodies. Patterns in the wake development are significant to force generation, but it is not trivial to quantitatively relate changes in the wake to changes in measured forces. Key difficulties in this regard include: (i) accurate quantification of velocities close to the body, and (ii) the effect of missing velocity or vorticity data in regions where optical access is obscured. In the present work, we consider force formulations based on the vorticity field, wherein mathematical manipulation eliminates the need for accurate near-body velocity information. Attention is restricted to nominally two dimensional problems, namely (i) a linearly accelerating flat plate, investigated using PIV in a water tunnel, and (ii) a pitching plate in a freestream flow, as investigated numerically by Wang & Eldredge (2013). The effect of missing vorticity data on the pressure side of the plate has a significant impact on the calculation of force for the pitching plate test case. Fortunately, if the vorticity on the pressure side remains confined to a thin boundary layer, simple corrections can be applied to recover a force estimate.
Cho, Jae Hyun; Batta, A.; Casamassima, V.; Cheng, X.; Choi, Yong Joon; Hwang, Il Soon; Lim, Jun; Meloni, P.; Nitti, F. S.; Dedul, V.; Kuznetsov, V.; Komlev, O.; Jaeger, W.; Sedov, A.; Kim, Ji Hak; Puspitarini, D.
2011-08-01
As highly promising coolant for new generation nuclear reactors, liquid Lead-Bismuth Eutectic has been extensively worldwide investigated. With high expectation about this advanced coolant, a multi-national systematic study on LBE was proposed in 2007, which covers benchmarking of thermal hydraulic prediction models for Lead-Alloy Cooled Advanced Nuclear Energy System (LACANES). This international collaboration has been organized by OECD/NEA, and nine organizations - ENEA, ERSE, GIDROPRESS, IAEA, IPPE, KIT/IKET, KIT/INR, NUTRECK, and RRC KI - contribute their efforts to LACANES benchmarking. To produce experimental data for LACANES benchmarking, thermal-hydraulic tests were conducted by using a 12-m tall LBE integral test facility, named as Heavy Eutectic liquid metal loop for integral test of Operability and Safety of PEACER (HELIOS) which has been constructed in 2005 at the Seoul National University in the Republic of Korea. LACANES benchmark campaigns consist of a forced convection (phase-I) and a natural circulation (phase-II). In the forced convection case, the predictions of pressure losses based on handbook correlations and that obtained by Computational Fluid Dynamics code simulation were compared with the measured data for various components of the HELIOS test facility. Based on comparative analyses of the predictions and the measured data, recommendations for the prediction methods of a pressure loss in LACANES were obtained. In this paper, results for the forced convection case (phase-I) of LACANES benchmarking are described.
Density-functional calculation of van der Waals forces for free-electron-like surfaces
DEFF Research Database (Denmark)
Hult, E.; Hyldgaard, P.; Rossmeisl, Jan;
2001-01-01
A recently proposed general density functional for asymptotic van der Waals forces is used to calculate van der Waals coefficients and reference-plane positions for realistic low-indexed Al surfaces. Results are given for a number of atoms and molecules outside the surfaces, as well as for the in......A recently proposed general density functional for asymptotic van der Waals forces is used to calculate van der Waals coefficients and reference-plane positions for realistic low-indexed Al surfaces. Results are given for a number of atoms and molecules outside the surfaces, as well...... as for the interaction between the surfaces themselves. The densities and static image-plane positions that are needed as input in the van der Waals functional are calculated self-consistently within density-functional theory using the generalized-gradient approximation, pseudopotentials, and plane waves. This study...... shows that the van der Waals density functional is applicable to realistic surfaces. The need for physically correct surface models, especially for open surfaces, is also illustrated. Finally the parameters for the anisotropic interaction of O-2 with Al are calculated....
Energy Technology Data Exchange (ETDEWEB)
Stefani, Giovanni Laranjo de; Conti, Thadeu das Neves; Fedorenko, Giuliana G.; Castro, Vinicius A.; Maio, Mireia F., E-mail: gstefani@ipen.b, E-mail: tnconti@ipen.b, E-mail: g.fedorenko@ipen.b, E-mail: vcastro@ipen.b, E-mail: mfmaio@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Santos, Thiago Augusto dos, E-mail: tsantos@ipen.b [Universidade de Sao Paulo (IFUSP), Sao Paulo, SP (Brazil). Inst. de Fisica
2011-07-01
This work objective was to create a manager program that would automate the programs and computer codes in use for neutronic calculation and thermo-hydraulic in IEA-R1 reactor thus making the process for calculation of safety parameters and for configuration change up to 98% faster than that used in the reactor today. This process was tested in combination with the reactor operators and is being implemented by the quality department. The main codes and programs involved in the calculations of configuration change are Leopard, Hammier-Technion, Twodb, Citation and Cobra. Calculations of delayed neutron and criticality coefficients given in the process of safety parameters calculation are given by the Hammer-Technion and Citation in a process that involves about eleven repetitions so that it meets all the necessary conditions (such different temperatures of the moderator and fuel). The results are entirely consistent with the expected and absolutely the same as those given by manual process. Thus the work shows its reliability as well the advantage of saving time, once a process that could take up to four hours was turned in one that takes around five minutes when done in a home computer. Much of this advantage is due to the fact that were created subprograms to treat the output of each program used and transform them into the input of the other programs, removing from it the intermediate essential data for this to occur, thus avoiding also a possible human error by handling the various data supplied. (author)
On improving the algorithm efficiency in the particle-particle force calculations
Kozynchenko, Alexander I.; Kozynchenko, Sergey A.
2016-09-01
The problem of calculating inter-particle forces in the particle-particle (PP) simulation models takes an important place in scientific computing. Such simulation models are used in diverse scientific applications arising in astrophysics, plasma physics, particle accelerators, etc., where the long-range forces are considered. The inverse-square laws such as Coulomb's law of electrostatic forces and Newton's law of universal gravitation are the examples of laws pertaining to the long-range forces. The standard naïve PP method outlined, for example, by Hockney and Eastwood [1] is straightforward, processing all pairs of particles in a double nested loop. The PP algorithm provides the best accuracy of all possible methods, but its computational complexity is O (Np2), where Np is a total number of particles involved. Too low efficiency of the PP algorithm seems to be the challenging issue in some cases where the high accuracy is required. An example can be taken from the charged particle beam dynamics where, under computing the own space charge of the beam, so-called macro-particles are used (see e.g., Humphries Jr. [2], Kozynchenko and Svistunov [3]).
ANALYSIS AND ESTIMATION OF HYDRAULIC STABILITY OF FRANCIS HYDRO TURBINE
Institute of Scientific and Technical Information of China (English)
LAI Xi-de
2004-01-01
With the development of large-capacity hydro turbines, the hydraulic instability of bydro turbines has become one of the most important problems that affect the stable operation of the hydro-electric units. The hydraulic vibration and unstable operation of Francis hydro turbines are primarily caused by the unsteady pressure pulsations inside draft tubes.The forced rotating vortex core at the runner exit and the channel vortices inside Francis turbine runners are origins of the unsteady pressure pulsations when operating at partial load. This paper briefly analyzes the hydraulic instability of operation caused by the vortex core and channel vortices at partial load, then, presents a way to estimate the hydraulic stability by calculation of the flow behavior at the runner exit.The validity of estimation is examined by comparison with experimental data. This will be helpful to evaluate the alternative design and predict the hydraulic stability for both the prototype and model hydro turbines.
Particle in cell calculation of plasma force on a small grain in a non-uniform collisional sheath
Hutchinson, I H
2013-01-01
The plasma force on grains of specified charge and height in a collisional plasma sheath are calculated using the multidimensional particle in cell code COPTIC. The background ion velocity distribution functions for the unperturbed sheath vary substantially with collisionality. The grain force is found to agree quite well with a combination of background electric field force plus ion drag force. However, the drag force must take account of the non-Maxwellian (and spatially varying) ion distribution function, and the collisional drag enhancement. It is shown how to translate the dimensionless results into practical equilibrium including other forces such as gravity.
Energy Technology Data Exchange (ETDEWEB)
Kotsarev, Alexander; Lizorkin, Mikhail [National Research Centre ' Kurchatov Institute' , Moscow (Russian Federation); Bencik, Marek; Hadek, Jan [UJV Rez, a.s., Rez (Czech Republic); Kozmenkov, Yaroslav; Kliem, Soeren [Helmholtz-Zentrum Dresden-Rossendorf (HZDR) e.V., Dresden (Germany)
2016-09-15
The 7th AER dynamic benchmark is a continuation of the efforts to validate the codes systematically for the estimation of the transient behavior of VVER type nuclear power plants. The main part of the benchmark is the simulation of the re-connection of an isolated circulation loop with low temperature in a VVER-440 plant. This benchmark was calculated by the National Research Centre ''Kurchatov Institute'' (with the code ATHLET/BIPR-VVER), UJV Rez (with the code RELAP5-3D {sup copyright}) and HZDR (with the code DYN3D/ATHLET). The paper gives an overview of the behavior of the main thermal hydraulic and neutron kinetic parameters in the provided solutions.
Energy Technology Data Exchange (ETDEWEB)
Perez, Daniel Milian; Lorenzo, Daniel E. Milian; Garcia, Lorena P. Rodriguez; Llanes, Jesus Salomon; Hernandez, Carlos R. Garcia, E-mail: dperez@instec.cu, E-mail: dmilian@instec.cu, E-mail: lorenapilar@instec.cu, E-mail: cgh@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Lira, Carlos A. Brayner de Oliveira, E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Rodriguez, Manuel Cadavid, E-mail: mcadavid2001@yahoo.com [Tecnologia Nuclear Medica Spa, TNM (Chile)
2015-07-01
{sup 99m}Tc is the most common radioisotope used in nuclear medicine. It is a very useful radioisotope, which is used in about 30-40 million procedures worldwide every year. Medical diagnostic imaging techniques using {sup 99m}Tc represent approximately 80% of all nuclear medicine procedures. Although {sup 99m}Tc can be produced directly on a cyclotron or other type of particle accelerator, currently is almost exclusively produced from the beta-decay of its 66-h parent {sup 99}Mo. {sup 99}Mo production system in an Aqueous Homogeneous Reactor (AHR) is potentially advantageous because of its low cost, small critical mass, inherent passive safety, and simplified fuel handling, processing and purification characteristics. In this paper, an AHR conceptual design using Low Enriched Uranium (LEU) is studied and optimized for the production of {sup 99}Mo. Aspects related with the neutronic behavior such as optimal reflector thickness, critical height, medical isotopes production and the reactivity feedback introduced in the solution by the volumetric expansion of the fuel solution due to thermal expansion of the fuel solution and the void volume generated by radiolytic gas bubbles were evaluated. Thermal-hydraulics studies were carried out in order to show that sufficient cooling capacity exists to prevent fuel overheating. The neutronic and thermal-hydraulics calculations have been performed with the MCNPX computational code and the version 14 of ANSYS CFX respectively. The neutronic calculations demonstrated that the reactor is able to produce 370 six-day curies of {sup 99}Mo in 5 days operation cycles and the CFD simulation demonstrated that the heat removal systems provide sufficient cooling capacity to prevent fuel overheating, the maximum temperature reached by the fuel (89.29 deg C) was smaller to the allowable temperature limit (90 deg C). (author)
Bradshaw, Richard T; Essex, Jonathan W
2016-08-09
Hydration free energy (HFE) calculations are often used to assess the performance of biomolecular force fields and the quality of assigned parameters. The AMOEBA polarizable force field moves beyond traditional pairwise additive models of electrostatics and may be expected to improve upon predictions of thermodynamic quantities such as HFEs over and above fixed-point-charge models. The recent SAMPL4 challenge evaluated the AMOEBA polarizable force field in this regard but showed substantially worse results than those using the fixed-point-charge GAFF model. Starting with a set of automatically generated AMOEBA parameters for the SAMPL4 data set, we evaluate the cumulative effects of a series of incremental improvements in parametrization protocol, including both solute and solvent model changes. Ultimately, the optimized AMOEBA parameters give a set of results that are not statistically significantly different from those of GAFF in terms of signed and unsigned error metrics. This allows us to propose a number of guidelines for new molecule parameter derivation with AMOEBA, which we expect to have benefits for a range of biomolecular simulation applications such as protein-ligand binding studies.
A novel treatment of the proton-proton Coulomb force in proton-deuteron Faddeev calculations
Directory of Open Access Journals (Sweden)
Glöckle W.
2010-04-01
Full Text Available We present resently introduced novel approach to include th e proton-proton (pp Coulomb force into the momentum space three-nucleon (3N Faddeev calculations. It is based on a standard formulation for short range forces and relies on a screening of the long-range Coul omb interaction. In order to avoid all uncertainties connected with an application of the partial wave expansion, unsuitable when working with long-range forces, we apply directly the 3-dimensional pp screened Coulomb t-matrix. That main new ingredient, the 3-dimensional screened pp Coulomb t-matrix, is obtained by a numerical sol ution of the 3-dimensional Lippmann-Schwinger (LS equation. Using a simple dynamical model for the nuclear part of the interaction we demonstrate the feasibility of that approach. The physical elastic pd scattering amplitude has a well deﬁned screening limit and does not require renormalisation. Well converged elastic pd cro ss sections are obtained at ﬁnite screening radii. Also the proton-deuteron (pd breakup observables can be determ ined from the resulting on-shell 3N amplitudes increasing the screening radius. However, contrary to the pd e lastic scattering, the screening limit exists only after renormalisation of the pp t-matrices.
Directory of Open Access Journals (Sweden)
A. E. Vinogradov
2008-01-01
Full Text Available An induction seismic receiver is widely applied in many guarding devices (1К18 «Realiya», PS-75 «Gerb» and others which are used for detection of moving surface objects. The receiver makes it possible to register soil vibrations caused by the object action. An inertial element of such seismic receiver is a cylindrical coil connected with the body by means of two flat springs.The paper proposes a method for calculation of electromotive force (EMF at induction seismic receiver output when it is exposed to seismic Relay wave on the basis of a differential equation for motion of the inertial element with due account of transient processes of forced vibrations and damping. The seismic receiver damping is a coil form where k of the spool, in which surface Foucault currents are induced.Results of modeling and experimental investigations have shown that the proposed methodology for EMF calculation, which is induced in the seismic receiver, allows faithfully to model signals at induction seismic receiver output that can be rather useful for mathematical modeling of surface object motion seismograms.
Institute of Scientific and Technical Information of China (English)
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，
Analysis for Clamping Force of Hydraulic Slide-valve Spool Based on Fluent%基于Fluent的液压滑阀阀芯卡紧力研究
Institute of Scientific and Technical Information of China (English)
陈奎生; 周雯娟; 郭媛; 付曙光; 张宏伟; 蒋俊
2011-01-01
Through simulation and analysis, the changes in clamping force of the hydraulic slide-valve spool when the spool skewed were studied, with no pressure-equalizing grooves, three rectangular grooves, five rectangular grooves and five triangular grooves. The simulation results show; opening pressure-equalizing grooves in the valve can reduce clamping force; the more pressure equalizing grooves open, the smaller the clamping force becomes. With the same amount, clamping force of spool with rectangular grooves is larger than that with triangle grooves, but the spool with rectangular grooves is more conducive to become concentric.%通过仿真分析,研究液压滑阀阀芯在不开均压槽、开3条矩形槽、开5条矩形槽、开5条三角形槽4种情况下,阀芯歪斜时阀芯卡紧力的变化.由仿真结果可知:阀芯歪斜时,在阀芯上开均压槽可以有效减小卡紧力,开的均压槽越多,卡紧力越小；开相同数量的矩形槽比三角槽的卡紧力大,但是更利于使阀芯趋于同心.
Extending the capability of GYRE to calculate tidally forced stellar oscillations
Guo, Zhao; Gies, Douglas R.
2016-01-01
Tidally forced oscillations have been observed in many eccentric binary systems, such as KOI-54 and many other 'heart beat stars'. The tidal response of the star can be calculated by solving a revised stellar oscillations equations.The open-source stellar oscillation code GYRE (Townsend & Teitler 2013) can be used to solve the free stellar oscillation equations in both adiabatic and non-adiabatic cases. It uses a novel matrix exponential method which avoids many difficulties of the classical shooting and relaxation method. The new version also includes the effect of rotation in traditional approximation.After showing the code flow of GYRE, we revise its subroutines and extend its capability to calculate tidallyforced oscillations in both adiabatic and non-adiabatic cases following the procedure in the CAFein code (Valsecchi et al. 2013). In the end, we compare the tidal eigenfunctions with those calculated from CAFein.More details of the revision and a simple version of the code in MATLAB can be obtained upon request.
Homentcovschi, Dorel; Murray, Bruce T.; Miles, Ronald N.
2013-01-01
There are a number of applications for microstructure devices consisting of a regular pattern of perforations, and many of these utilize fluid damping. For the analysis of viscous damping and for calculating the spring force in some cases, it is possible to take advantage of the regular hole pattern by assuming periodicity. Here a model is developed to determine these quantities based on the solution of the Stokes' equations for the air flow. Viscous damping is directly related to thermal-mechanical noise. As a result, the design of perforated microstructures with minimal viscous damping is of real practical importance. A method is developed to calculate the damping coefficient in microstructures with periodic perforations. The result can be used to minimize squeeze film damping. Since micromachined devices have finite dimensions, the periodic model for the perforated microstructure has to be associated with the calculation of some frame (edge) corrections. Analysis of the edge corrections has also been performed. Results from analytical formulas and numerical simulations match very well with published measured data. PMID:24058267
Energy Technology Data Exchange (ETDEWEB)
Kutepov, A L
2004-01-08
Linear-response (LR) theory in combination with the first-principles band structure codes allows to calculate phonons in an efficient way. In this report a formalism which enables us to apply LR theory within an all-electron framework utilizing the relativistic full-potential linearized augmented plane-wave (RFLAPW) method is presented. As first part, the equations for the calculations of the atomic forces are given and they are used for the calculation of forces in {alpha}-Pu. As a second step, a complete set of formulaes for the dynamic matrices calculation is presented.
A finite-volume numerical method to calculate fluid forces and rotordynamic coefficients in seals
Athavale, M. M.; Przekwas, A. J.; Hendricks, R. C.
1992-01-01
A numerical method to calculate rotordynamic coefficients of seals is presented. The flow in a seal is solved by using a finite-volume formulation of the full Navier-Stokes equations with appropriate turbulence models. The seal rotor is perturbed along a diameter such that the position of the rotor is a sinusoidal function of time. The resulting flow domain changes with time, and the time-dependent flow in the seal is solved using a space conserving moving grid formulation. The time-varying fluid pressure reaction forces are then linked with the rotor center displacement, velocity and acceleration to yield the rotordynamic coefficients. Results for an annular seal are presented, and compared with experimental data and other more simplified numerical methods.
Calculation of the static forces acting on ACV bag-finger skirts
Xie, Y. N.; Hua, Y.
A mathematical model of the geometry formation of an ACV bag-finger skirt is developed to determine skirt shape and its deflection for varying cushion pressures, and calculations for the reactions of supports of the rigid structure on the skirt at the inner and outer attachment points are obtained. The model assumption that the finger triangle of the two-dimensional bag-finger skirt turns around the inner attachment point with changing ratio of cushion pressure to bag pressure is confirmed by experiments using skirt rigs. Good agreement is found between theoretical and experimental results, and it is shown that when the cushion pressure is changing, the pressure ratio is the essential dimensionless parameter for the skirt geometry formation and its deflection, and for the forces acting on it.
A Transport Equation Approach to Green Functions and Self-force Calculations
Wardell, Barry
2010-01-01
In a recent work, we presented the first application of the Poisson-Wiseman-Anderson method of `matched expansions' to compute the self-force acting on a point particle moving in a curved spacetime. The method employs two expansions for the Green function which are respectively valid in the `quasilocal' and `distant past' regimes, and which may be matched together within the normal neighbourhood. In this article, we introduce the method of matched expansions and discuss transport equation methods for the calculation of the Green function in the quasilocal region. These methods allow the Green function to be evaluated throughout the normal neighborhood and are also relevant to a broad range of problems from radiation reaction to quantum field theory in curved spacetime and quantum gravity.
A practical, covariant puncture for second-order self-force calculations
Pound, Adam
2014-01-01
Accurately modeling an extreme-mass-ratio inspiral requires knowledge of the second-order gravitational self-force on the inspiraling small object. Recently, numerical puncture schemes have been formulated to calculate this force, and their essential analytical ingredients have been derived from first principles. However, the \\emph{puncture}, a local representation of the small object's self-field, in each of these schemes has been presented only in a local coordinate system centered on the small object, while a numerical implementation will require the puncture in coordinates covering the entire numerical domain. In this paper we provide an explicit covariant self-field as a local expansion in terms of Synge's world function. The self-field is written in the Lorenz gauge, in an arbitrary vacuum background, and in forms suitable for both self-consistent and Gralla-Wald-type representations of the object's trajectory. We illustrate the local expansion's utility by sketching the procedure of constructing from i...
Practical, covariant puncture for second-order self-force calculations
Pound, Adam; Miller, Jeremy
2014-05-01
Accurately modeling an extreme-mass-ratio inspiral requires knowledge of the second-order gravitational self-force on the inspiraling small object. Recently, numerical puncture schemes have been formulated to calculate this force, and their essential analytical ingredients have been derived from first principles. However, the "puncture," a local representation of the small object's self-field, in each of these schemes has been presented only in a local coordinate system centered on the small object, while a numerical implementation will require the puncture in coordinates covering the entire numerical domain. In this paper we provide an explicit covariant self-field as a local expansion in terms of Synge's world function. The self-field is written in the Lorenz gauge, in an arbitrary vacuum background, and in forms suitable for both self-consistent and Gralla-Wald-type representations of the object's trajectory. We illustrate the local expansion's utility by sketching the procedure of constructing from it a numerically practical puncture in any chosen coordinate system.
Rapid Calculation of Thermal Forces in Coarse Grained Simulation of Colloidal Particles
Swan, James; Fiore, Andrew; Donev, Aleksander; Balboa, Florencio
2016-11-01
In the presented work, we will demonstrate a spectrally accurate method for calculation of thermal forces in implicit solvent simulations of soft materials such as colloidal dispersions. For implicit solvent models, the stochastic forces must be drawn from a normal distribution whose covariance is a complicated function of the particle configuration. For a system of interacting N particles, drawing a single sample requires O (N3) operations, if numerically exact techniques from linear algebra are employed. So-called "fast" methods can approximate the sampling with roughly O (Nm logN) computational complexity, where m is a coefficient greater than one which depends on the configuration of the particles. The computational complexity of the presented approach is O (N(logN) d / (d + 3)) , where d is the fractal dimension of the particulate structures being modeled. Remarkably, this new approach adapts to the structure of the material under study by leveraging the algebraic structure of Ewald summation and balancing the computational effort spent evaluating near-field and far-field contributions to the hydrodynamic interactions among the suspended particles. Applications of this approach to modeling colloidal gelation and particulate suspensions will be discussed.
MHD Calculation of halo currents and vessel forces in NSTX VDEs
Breslau, J. A.; Strauss, H. R.; Paccagnella, R.
2012-10-01
Research tokamaks such as ITER must be designed to tolerate a limited number of disruptions without sustaining significant damage. It is therefore vital to have numerical tools that can accurately predict the effects of these events. The 3D nonlinear extended MHD code M3D [1] can be used to simulate disruptions and calculate the associated wall currents and forces. It has now been validated against halo current data from NSTX experiments in which vertical displacement events (VDEs) were deliberately induced by turning off vertical feedback control. The results of high-resolution numerical simulations at realistic Lundquist numbers show reasonable agreement with the data, supporting a model in which the most dangerously asymmetric currents and heat loads, and the largest horizontal forces, arise in situations where a fast-growing ideal 2,1 external kink mode is destabilized by the scraping-off of flux surfaces with safety factor q>2 during the course of the VDE. [4pt] [1] W. Park, et al., Phys. Plasmas 6 (1999) 1796.
Directory of Open Access Journals (Sweden)
Jonathan S. Merritt
2008-01-01
Full Text Available The equine distal forelimb is a common location of injuries related to mechanical overload. In this study, a two-dimensional model of the musculoskeletal system of the region was developed and applied to kinematic and kinetic data from walking and trotting horses. The forces in major tendons and joint reaction forces were calculated. The components of the joint reaction forces caused by wrapping of tendons around sesamoid bones were found to be of similar magnitude to the reaction forces between the long bones at each joint. This finding highlighted the importance of taking into account muscle-tendon wrapping when evaluating joint loading in the equine distal forelimb.
Indian Academy of Sciences (India)
Ankur Kumar; Jyeshtharaj B Joshi; Arun K Nayak; Pallippattu K Vijayan
2015-05-01
In this paper, a review is presented on the experimental investigations and the numerical simulations performed to analyze the thermal-hydraulic performance of the air-cooled heat exchangers. The air-cooled heat exchangers mostly consist of the finned-tube bundles. The primary role of the extended surfaces (fins) is to provide more heat transfer area to enhance the rate of heat transfer on the air side. The secondary role of the fins is to generate vortices, which help in enhancing the mixing and the heat transfer coefficient. In this study, the annular and plate fins are considered, the annular fins are further divided into four categories: (1) plane annular fins, (2) serrated fins, (3) crimped spiral fins, (4) perforated fins, and similarly for the plate fins, the fin types are: (1) plain plate fins, (2) wavy plate fins, (3) plate fins with DWP, and (4) slit and strip fins. In Section 4, the performance of the various types of fins is presented with respect to the parameters: (1) Reynolds number, (2) fin pitch, (3) fin height, (4) fin thickness, (5) tube diameter, (6) tube pitch, (7) tube type, (8) number of tube rows, and (9) effect of dehumidifying conditions. In Section 5, the conclusions and the recommendations for the future work have been given.
Ergün, A Sanlı
2011-10-01
Focused ultrasound therapy relies on acoustic power absorption by tissue. The stronger the absorption the higher the temperature increase is. However, strong acoustic absorption also means faster attenuation and limited penetration depth. Hence, there is a trade-off between heat generation efficacy and penetration depth. In this paper, we formulated the acoustic power absorption as a function of frequency and attenuation coefficient, and defined two figures of merit to measure the power absorption: spatial peak of the acoustic power absorption density, and the acoustic power absorbed within the focal area. Then, we derived "rule of thumb" expressions for the optimum frequencies that maximized these figures of merit given the target depth and homogeneous tissue type. We also formulated a method to calculate the optimum frequency for inhomogeneous tissue given the tissue composition for situations where the tissue structure can be assumed to be made of parallel layers of homogeneous tissue. We checked the validity of the rules using linear acoustic field simulations. For a one-dimensional array of 4cm acoustic aperture, and for a two-dimensional array of 4×4cm(2) acoustic aperture, we found that the power absorbed within the focal area is maximized at 0.86MHz, and 0.79MHz, respectively, when the target depth is 4cm in muscle tissue. The rules on the other hand predicted the optimum frequencies for acoustic power absorption as 0.9MHz and 0.86MHz, respectively for the 1D and 2D array case, which are within 6% and 9% of the field simulation results. Because radiation force generated by an acoustic wave in a lossy propagation medium is approximately proportional to the acoustic power absorption, these rules can be used to maximize acoustic radiation force generated in tissue as well.
Directory of Open Access Journals (Sweden)
Orlov Vladimir
2017-01-01
Full Text Available The lifetime of the pipeline, which undergoes trenchless repair by pulling and then fixing various types of internal protective coatings inside, is determined by the strength characteristics of the two-layer structure “old pipeline + internal protective coating”. Hydraulic parameters of internal protective coatings, such as surface roughness and degree of hydrophobicity (water repellency, can play a role in prolonging the life of the repaired pipeline. With a high degree of hydrophobicity of the protective coating, the contact of the transported liquid with the walls of the pipeline during its operation in the non-pressure regime decreases, which leads to a decrease in the negative impact on the walls, in particular, their attrition, interaction with the specific structure of the coating material, which in turn reduces the energy costs when transporting water. Given article deals with a mathematical description of the interaction of the surface structure (with its inherent wetting ability and the transported liquid in a mini-stream created on an inclined open chute imitating the inner surface of a pressureless pipeline. The theoretical positions and methodology for calculating the degree of hydrophobicity are based on research conducted on the basis of frontal and coaxial (along the flow digital photo and video. T
Harrison, R. J.; Feinberg, J. M.
2007-12-01
First-order reversal curves (FORCs) are a powerful method for characterizing the magnetic hysteresis properties of natural and synthetic materials, and are rapidly becoming a standard tool in rock magnetic and paleomagnetic investigations. Here we describe a modification to existing algorithms for the calculation of FORC diagrams using locally-weighted regression smoothing (often referred to as loess smoothing). Like conventional algorithms, the FORC distribution is calculated by fitting a second degree polynomial to a region of FORC space defined by a smoothing factor, N. Our method differs from conventional algorithms in two ways. Firstly, rather than a square of side (2N+1) centered on the point of interest, the region of FORC space used for fitting is defined as a span of arbitrary shape encompassing the (2N+1)2 data points closest to the point of interest. Secondly, data inside the span are given a weight that depends on their distance from the point being evaluated: data closer to the point being evaluated have higher weights and have a greater effect on the fit. Loess smoothing offers two advantages over current methods. Firstly, it allows the FORC distribution to be calculated using a constant smoothing factor all the way to the Hc = 0 axis. This eliminates possible distortions to the FORC distribution associated with reducing the smoothing factor close to the Hc = 0 axis, and does not require use of the extended FORC formalism and the reversible ridge, which swamps the low-coercivity signal. Secondly, it allows finer control over the degree of smoothing applied to the data, enabling automated selection of the optimum smoothing factor for a given FORC measurement, based on an analysis of the standard deviation of the fit residuals. The new algorithm forms the basis for FORCinel, a new suite of FORC analysis tools for Igor Pro (www.wavemetrics.com), freely available on request from the authors.
Hydraulic manipulator research at ORNL
Energy Technology Data Exchange (ETDEWEB)
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.
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 ...
Institute of Scientific and Technical Information of China (English)
李中荣; 顾烈烽
2011-01-01
This study was carried out to improve the stepwise calculation method of hydraulic calculation for designing micro-irrigation plot,whose branch pipes and laterals were laid under positive and reverse slope condition. Typical case showed that emitters’ average flow of irrigation plot was equal to emitters’ design flow,flow deviation rate was less than that of permission, the results satisfied the requirements of design regulation. At the same time,the stepwise calculation could provide the theoretical basis for controlling the pressure in microirrigation plot,determining the flow and design pressure.%改进一种对由支、毛管均为顺逆坡铺设时所构成的灌水小区的水力计算详算法.该法将用于一条毛管水力计算的详算法扩至整个灌水小区,将一条毛管在支管上双向布置位置选择扩至小区内均为顺、逆坡布置的支管和所有毛管,通过计算机快速求出各管段、各孔口的压力、流量值.通过实例计算表明,灌水小区内灌水器流量的平均值等于灌水器设计流量,满足规范规定的设计要求.同时,该计算方法可为微灌灌水小区压力、流量的确定和设置压力(流量)控制(调节)设备提供理论设计参数依据.
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)
Directory of Open Access Journals (Sweden)
Kyung-Duk Park
2015-07-01
Full Text Available The ice-resistance estimation technique for icebreaking ships had been studied intensively over recent years to meet the needs of designing Arctic vessels. Before testing in the ice model basin, the estimation of a ship’s ice resistance with high reliability is very important to decide the delivered power necessary for level ice operation. The main idea of previous studies came from several empirical formulas, such as Poznyak and Ionov (1981, Enkvist (1972 and Shimansky (1938 methods, in which ice resistance components such as icebreaking, buoyancy and clearing resistances were represented by the integral equations along the Design Load Water Line (DLWL. The current study proposes a few modified methods not only considering the DLWL shape, but also the hull shape under the DLWL. In the proposed methodology, the DLWL shape for icebreaking resistance and the hull shape under the DLWL for buoyancy and clearing resistances can be directly considered in the calculation. Especially, when calculating clearing resistance, the flow pattern of ice particles under the DLWL of ship is assumed to be in accordance with the ice flow observed during ice model testing. This paper also deals with application examples for a few ship designs and its ice model testing programs at the AARC ice model basin. From the comparison of results of the model test and the estimation, the reliability of this estimation technique has been discussed.
CRITICALITY CURVES FOR PLUTONIUM HYDRAULIC FLUID MIXTURES
Energy Technology Data Exchange (ETDEWEB)
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.
Institute of Scientific and Technical Information of China (English)
刘会会; 符永正
2012-01-01
对于热水供暖异程系统,工程设计中常用的水力计算方法是等温降法,且从最远立管环路开始计算。这种方法因为受最小管径的限制,往往难以实现各立管环路之间的水力平衡,而必需借助阀门才能实现水力平衡。本文通过计算实例说明,从最近立管环路开始计算,则可以很好地实现各立管环路之间的水力平衡,而无需借助阀门,并给出了这种方法的计算顺序。%For the hot water heating direct return system, the common hydraulic calculation method of engineering design is constant temperature drop method, which is calculated from the farthest riser loop. Because of the minimum diameter restriction, it is usually difficult to realize the hydraulic balance of every riser loop. Under such conditions, the system can meet the demand of hydraulic balance using valves. In the paper, through a calculation example it is shown that every riser loop is very easy to realize hydraulic balance without using valves when the system is calculated from the nearest riser loop. Besides, the calculation order of this method is given.
Efficient calculation of chiral three-nucleon forces up to N3LO for ab initio studies
Hebeler, K; Epelbaum, E; Golak, J; Skibinski, R
2015-01-01
We present a novel framework to decompose three-nucleon forces in a momentum space partial-wave basis. The new approach is computationally much more efficient than previous methods and opens the way to ab initio studies of few-nucleon scattering processes, nuclei and nuclear matter based on higher-order chiral 3N forces. We use the new framework to calculate matrix elements of chiral three-nucleon forces at N2LO and N3LO in large basis spaces and carry out benchmark calculations for neutron matter and symmetric nuclear matter. We also study the size of the individual three-nucleon force contributions for $^3$H. For nonlocal regulators, we find that the sub-leading terms, which have been neglected in most calculations so far, provide important contributions. All matrix elements are calculated and stored in a user-friendly way, such that values of low-energy constants as well as the form of regulator functions can be chosen freely.
Wang, Hsiang-Hsu; Taam, Ronald E
2015-01-01
Investigating the evolution of disk galaxies and the dynamics of proto-stellar disks can involve the use of both a hydrodynamical and a Poisson solver. These systems are usually approximated as infinitesimally thin disks using two- dimensional Cartesian or polar coordinates. In Cartesian coordinates, the calcu- lations of the hydrodynamics and self-gravitational forces are relatively straight- forward for attaining second order accuracy. However, in polar coordinates, a second order calculation of self-gravitational forces is required for matching the second order accuracy of hydrodynamical schemes. We present a direct algorithm for calculating self-gravitational forces with second order accuracy without artifi- cial boundary conditions. The Poisson integral in polar coordinates is expressed in a convolution form and the corresponding numerical complexity is nearly lin- ear using a fast Fourier transform. Examples with analytic solutions are used to verify that the truncated error of this algorithm is of seco...
Directory of Open Access Journals (Sweden)
Grković Vojin R.
2013-01-01
Full Text Available The paper presents the mathematical model and the procedure for calculation of the resultant force acting on the air cooled gas turbine blade(s based on the aerodynamic theory and computation of the circulation around the blade profile. In the conducted analysis was examined the influence of the cooling air mass flow expressed through the cooling air flow parameter λc, as well as, the values of the inlet and outlet angles β1 and β2, on the magnitude of the tangential and axial forces. The procedure and analysis were exemplified by the calculation of the tangential and axial forces magnitudes. [Projekat Ministarstva nauke Republike Srbije: Development and building the demonstrative facility for combined heat and power with gasification
An Approximate Method for Calculation of Fluid Force and Response of A Circular Cylinder at Lock-in
Institute of Scientific and Technical Information of China (English)
WANG Yi
2008-01-01
In this paper, equations calculating lift force of a rigid circular cylinder at lock-in in uniform flow are deduced in detail. Besides, equations calculating the lift force on a long flexible circular cylinder at lock-in are deduced based on mode analysis of a multi-degree freedom system. The simplified forms of these equations are also given. Furthermore, an approximate method to predict the forces and response of rigid circular cylinders and long flexible circular cylinders at lock-in is introduced in the case of low mass-damping ratio. A method to eliminate one deficiency of these equations is introduced. Comparison with experimental results shows the effectiveness of this approximate method.
Li, Ying; Chan, Maria K Y; Sankaranarayanan, Subramanian; Rouxb, Benoît
2016-01-01
In molecular dynamics (MD) simulation, force field determines the capability of an individual model in capturing physical and chemistry properties. The method for generating proper parameters of the force field form is the key component for computational research in chemistry, biochemistry, and condensed-phase physics. Our study showed that the feasibility to predict experimental condensed phase properties (i.e., density and heat of vaporization) of methanol through problem specific force field from only quantum chemistry information. To acquire the satisfying parameter sets of the force field, the genetic algorithm (GA) is the main optimization method. For electrostatic potential energy, we optimized both the electrostatic parameters of methanol using the GA method, which leads to low deviations of between the quantum mechanics (QM) calculations and the GA optimized parameters. We optimized the van der Waals (vdW) parameters both using GA and guided GA methods by calibrating interaction energy of various met...
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
Institute of Scientific and Technical Information of China (English)
罗渝; 许强; 何思明; 李新坡; 何尽川; 吴永
2015-01-01
A new method based on the multi-wedge translation mechanism is presented to calculate the lateral force acting on the stabilizing piles. At first, there is no assumption for the shape of potential sliding surface, it is just considered that the potential sliding surface is a composite of a number of straight lines. And then, the potential sliding mass is divided into a number of triangular wedges take with these straight lines as its base. The kinematic theorem of limit analysis is adopted to calculate the rate of external work and the rate of energy dissipation for each triangular wedge, respectively. Furthermore, the multivariate functions are established to calculate the lateral force acting on the stabilizing piles. The lateral force and the corresponding potential sliding surfaces can be obtained by an optimizational technique. At last, an example is taken to illustrate the method. The effect of soil strength parameters, slope angle and pile roughness on the lateral force and the corresponding potential sliding surface are analyzed. The result are compared with those obtained using other methods.
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;
Directory of Open Access Journals (Sweden)
Raiker Witter
2015-01-01
Full Text Available Polarization of atoms plays a substantial role in molecular interactions. Class I and II force fields mostly calculate with fixed atomic charges which can cause inadequate descriptions for highly charged molecules, for example, ion channels or metalloproteins. Changes in charge distributions can be included into molecular mechanics calculations by various methods. Here, we present a very fast computational quantum mechanical method, the Bond Polarization Theory (BPT. Atomic charges are obtained via a charge calculation method that depend on the 3D structure of the system in a similar way as atomic charges of ab initio calculations. Different methods of population analysis and charge calculation methods and their dependence on the basis set were investigated. A refined parameterization yielded excellent correlation of R=0.9967. The method was implemented in the force field COSMOS-NMR and applied to the histidine-tryptophan-complex of the transmembrane domain of the M2 protein channel of influenza A virus. Our calculations show that moderate changes of side chain torsion angle χ1 and small variations of χ2 of Trp-41 are necessary to switch from the inactivated into the activated state; and a rough two-side jump model of His-37 is supported for proton gating in accordance with a flipping mechanism.
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity,the kinematic parameters of the slide,connecting rod and crank were formulated approximately. On the basis of the results above,three inertia forces and the input moment in the mechanism during its idle running were investigated and fo...
Kawai, Shigeki; Sadeghi, Ali; Xu, Feng; Feng, Xu; Peng, Lifen; Lifen, Peng; Pawlak, Rémy; Glatzel, Thilo; Willand, Alexander; Orita, Akihiro; Otera, Junzo; Goedecker, Stefan; Meyer, Ernst
2013-10-22
State-of-the art experimental techniques such as scanning tunneling microscopy have great difficulties in extracting detailed structural information about molecules adsorbed on surfaces. By combining atomic force microscopy and Kelvin probe force microscopy with ab initio calculations, we demonstrate that we can obtain a wealth of detailed structural information about the molecule itself and its environment. Studying an FFPB molecule on a gold surface, we are able to determine its exact location on the surface, the nature of its bonding properties with neighboring molecules that lead to the growth of one-dimensional strips, and the internal torsions and bendings of the molecule.
An Improved Algorithm for Calculating Friction Force and Torque in Involute Helical Gears
Directory of Open Access Journals (Sweden)
Lin Han
2013-01-01
Full Text Available Time varying frictional force and torque are one of the main exciting sources of vibration in helical gears. This paper presents an approach to determine the friction force and torque in involute helical gears considering nonuniform load distribution along contact lines. An analytical load distribution model is employed and extended to obtain the load per unit of length along contact lines. Friction force and torque models under nonuniform assumption are derived. Comparisons of the determined friction force and torque with the results from uniform assumption are made. In addition, the differences between constant friction coefficient and varying coefficient are revealed. Moreover, two typical design cases of helical gears are studied. Results show that the fluctuations of friction force and torque under uniform assumption are more significant than those under nonuniform assumption in sample I for a single tooth, but less significant for the sum of those of the three teeth, while in sample II, the fluctuations under uniform assumption are less significant than those under nonuniform assumption. The friction coefficient induced difference is negligible compared with the difference induced by load distribution assumptions.
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...
Calculation of force distribution for a periodically supported beam subjected to moving loads
Hoang, T.; Duhamel, D.; Foret, G.; Yin, H. P.; Joyez, P.; Caby, R.
2017-02-01
In this study, a novel model for a periodically supported beam subjected to moving loads was developed using a periodicity condition on reaction forces. This condition, together with Fourier transforms and Dirac combs, forms a relation between the beam displacement and support reaction forces. This relation explains the force distribution at the supports, and holds for any type of support and foundation behaviors. Based on this relation, a system equivalence for a periodically supported beam is presented in this paper. An application to non-ballasted viscoelastic supports is presented as an example and the results clearly match the existing model. Next, an approximation of real-time responses was developed for the moving loads as periodic series. The comparison shows that this approximation can be used for a limited number of loads if the distances between loads are sufficiently large. The system equivalence for a periodically supported beam is efficient for supports with linear behavior, and could be extended to other behaviors.
Calculation of the Dynamic Characteristics of an Electric Arc Subjected to Forced Extinction
Nekrasov, S. A.
2016-11-01
Models and methods of calculating the currents in a free-burning arc and in an arc in an arc chute with magnetic blow and the voltages across them in the process of their extinction are considered. A comparison of calculation and experimental data has been performed.
Directory of Open Access Journals (Sweden)
I. I. Sergey
2005-01-01
Full Text Available The paper contains description of a simplified method for calculating closing-in of switch-gear flexible buses at short circuit. The developed method is based on integral and energy principles of mechanics. In order to increase accuracy of the calculation corrections factors are introduced in an explicit formula for calculation of maximum horizontal deviations. These factors have been obtained with the help of a computer program that realized numerical method for calculating closing-in of wires by flexible thread levels.Diagrams are constructed with the purpose to find ymax and criteria of electro-dynamic resistance of flexible buses (permissible impulse of electro-dynamic forces and current of electro-dynamic resistance is determined.
Hughes, Zak E; Wright, Louise B; Walsh, Tiffany R
2013-10-29
The molecular simulation of biomolecules adsorbed at noble metal interfaces can assist in the development of bionanotechnology applications. In line with advances in polarizable force fields for adsorption at aqueous gold interfaces, there is scope for developing a similar force field for silver. One way to accomplish this is via the generation of in vacuo adsorption energies calculated using first-principles approaches for a wide range of different but biologically relevant small molecules, including water. Here, we present such first-principles data for a comprehensive range of bio-organic molecules obtained from plane-wave density functional theory calculations using the vdW-DF functional. As reported previously for the gold force field, GolP-CHARMM (Wright, L. B.; Rodger, P. M.; Corni, S.; Walsh, T. R. GolP-CHARMM: first-principles based force-fields for the interaction of proteins with Au(111) and Au(100). J. Chem. Theory Comput. 2013, 9, 1616-1630), we have used these data to construct a a new force field, AgP-CHARMM, suitable for the simulation of biomolecules at the aqueous Ag(111) and Ag(100) interfaces. This force field is derived to be consistent with GolP-CHARMM such that adsorption on Ag and Au can be compared on an equal footing. Our force fields are used to evaluate the water overlayer stability on both silver and gold, finding good agreement with known behaviors. We also calculate and compare the structuring (spatial and orientational) of liquid water adsorbed at both silver and gold. Finally, we report the adsorption free energy of a range of amino acids at both the Au(111) and Ag(111) aqueous interfaces, calculated using metadynamics. Stronger adsorption on gold was noted in most cases, with the exception being the carboxylate group present in aspartic acid. Our findings also indicate differences in the binding free energy profile between silver and gold for some amino acids, notably for His and Arg. Our analysis suggests that the relatively
Directory of Open Access Journals (Sweden)
Wefstaedt Patrick
2009-11-01
Full Text Available Abstract Background Among other causes the long-term result of hip prostheses in dogs is determined by aseptic loosening. A prevention of prosthesis complications can be achieved by an optimization of the tribological system which finally results in improved implant duration. In this context a computerized model for the calculation of hip joint loadings during different motions would be of benefit. In a first step in the development of such an inverse dynamic multi-body simulation (MBS- model we here present the setup of a canine hind limb model applicable for the calculation of ground reaction forces. Methods The anatomical geometries of the MBS-model have been established using computer tomography- (CT- and magnetic resonance imaging- (MRI- data. The CT-data were collected from the pelvis, femora, tibiae and pads of a mixed-breed adult dog. Geometric information about 22 muscles of the pelvic extremity of 4 mixed-breed adult dogs was determined using MRI. Kinematic and kinetic data obtained by motion analysis of a clinically healthy dog during a gait cycle (1 m/s on an instrumented treadmill were used to drive the model in the multi-body simulation. Results and Discussion As a result the vertical ground reaction forces (z-direction calculated by the MBS-system show a maximum deviation of 1.75%BW for the left and 4.65%BW for the right hind limb from the treadmill measurements. The calculated peak ground reaction forces in z- and y-direction were found to be comparable to the treadmill measurements, whereas the curve characteristics of the forces in y-direction were not in complete alignment. Conclusion In conclusion, it could be demonstrated that the developed MBS-model is suitable for simulating ground reaction forces of dogs during walking. In forthcoming investigations the model will be developed further for the calculation of forces and moments acting on the hip joint during different movements, which can be of help in context with the in
Graybill, George
2007-01-01
Forces are at work all around us. Discover what a force is, and different kinds of forces that work on contact and at a distance. We use simple language and vocabulary to make this invisible world easy for students to ""see"" and understand. Examine how forces ""add up"" to create the total force on an object, and reinforce concepts and extend learning with sample problems.
Neslusan, L
2010-01-01
Considering two static, electrically charged, elementary particles, we demonstrate a possible way of proving that all known fundamental forces in the nature are the manifestations of the single, unique interaction. We re-define the gauging of integration constants in the Schwarzschild solution of Einstein field equations. We consider the potential energy in this context regardless it is gravitational or electric potential energy. With the newly gauged constants, we sketch how the unique interaction can be described with the help of an appropriate solution of the well-known Maxwell equations. According the solution, there are two zones, in the system of two oppositely charged particles, where the force is oscillating. The first particle can be in a stable, constant distance from the second particle, between the neighbouring regions of repulsion and attraction. In an outer oscillation zone, the corresponding energy levels in the proton-electron systems are identical (on the level of accuracy of values calculate...
Wang, Hsiang-Hsu; Yen, David C. C.; Taam, Ronald E.
2015-11-01
Investigating the evolution of disk galaxies and the dynamics of proto-stellar disks can involve the use of both a hydrodynamical and a Poisson solver. These systems are usually approximated as infinitesimally thin disks using two-dimensional Cartesian or polar coordinates. In Cartesian coordinates, the calculations of the hydrodynamics and self-gravitational forces are relatively straightforward for attaining second-order accuracy. However, in polar coordinates, a second-order calculation of self-gravitational forces is required for matching the second-order accuracy of hydrodynamical schemes. We present a direct algorithm for calculating self-gravitational forces with second-order accuracy without artificial boundary conditions. The Poisson integral in polar coordinates is expressed in a convolution form and the corresponding numerical complexity is nearly linear using a fast Fourier transform. Examples with analytic solutions are used to verify that the truncated error of this algorithm is of second order. The kernel integral around the singularity is applied to modify the particle method. The use of a softening length is avoided and the accuracy of the particle method is significantly improved.
Kaminski, George A.; Ponomarev, Sergei Y.; Liu, Aibing B.
2009-01-01
We are presenting POSSIM (POlarizable Simulations with Second order Interaction Model) – a software package and a set of parameters designed for molecular simulations. The key feature of POSSIM is that the electrostatic polarization is taken into account using a previously introduced fast formalism. This permits cutting computational cost of using the explicit polarization by about an order of magnitude. In this article, parameters for water, methane, ethane, propane, butane, methanol and NMA are introduced. These molecules are viewed as model systems for protein simulations. We have achieved our goal of ca. 0.5 kcal/mol accuracy for gas-phase dimerization energies and no more than 2% deviations in liquid state heats of vaporization and densities. Moreover, free energies of hydration of the polarizable methane, ethane and methanol have been calculated using the statistical perturbation theory. These calculations are a model for calculating protein pKa shifts and ligand binding affinities. The free energies of hydration were found to be 2.12 kcal/mol, 1.80 kcal/mol and −4.95 kcal/mol for methane, ethane and methanol, respectively. The experimentally determined literature values are 1.91 kcal/mol, 1.83 kcal/mol and −5.11 kcal/mol. The POSSIM average error in these absolute free energies of hydration is only about 0.13 kcal/mol. Using the statistical perturbation theory with polarizable force fields is not widespread, and we believe that this work opens road to further development of the POSSIM force field and its applications for obtaining accurate energies in protein-related computer modeling. PMID:20209038
Institute of Scientific and Technical Information of China (English)
Jim Wang; Sheng-dun Zhao; Hu-shan Shi; Chun-jian Hua
2009-01-01
A new method to calculate and counterbalance the inertia force of slider-crank mechanisms in high-speed mechanical presses was put forward. By analyzing the kinematic characteristics of a center-located slider-crank mechanism whose crank rotates at a constant angular velocity, the kinematic parameters of the slide, connecting rod and crank were formulated approximately. On the basis of the results above, three inertia forces and the input moment in the mechanism during its idle running were investigated and formulated by dynamic analysis. A verification experiment was performed on a slider-crank mechanism at a high-speed press machine. The forces derived from the established formulas were compared respectively with those obtained by the ADAMS software and the classical method of connecting rod mass substitution. It was experimentally found that the proposed formulas have an improved performance over related earlier techniques. By use of these results, a 1000 kN 1250 rpm four-point high-speed press machine was designed and manufactured. The slide of this press is driven by four sets of slider-crank mechanisms with symmetrical layout and opposite rotation directions to counterbalance the horizontal inertia forces. Four eccentric counterbalance blocks were designed to counterbalance the vertical force after their mass and equivalent eccentric radius were formulated. The high-speed press machine designed by the proposed counterbalance method has worked with satisfactory performance and good dynamic balance for more than four years in practical production.
Rai, Neeraj; Tiwari, Surya P; Maginn, Edward J
2012-09-06
Advances in computational algorithms and methodologies make it possible to use highly accurate quantum mechanical calculations to develop force fields (pair-wise additive intermolecular potentials) for condensed phase simulations. Despite these advances, this approach faces numerous hurdles for the case of actinyl ions, AcO2(n+) (high-oxidation-state actinide dioxo cations), mainly due to the complex electronic structure resulting from an interplay of s, p, d, and f valence orbitals. Traditional methods use a pair of molecules (“dimer”) to generate a potential energy surface (PES) for force field parametrization based on the assumption that many body polarization effects are negligible. We show that this is a poor approximation for aqueous phase uranyl ions and present an alternative approach for the development of actinyl ion force fields that includes important many body solvation effects. Force fields are developed for the UO2(2+) ion with the SPC/Fw, TIP3P, TIP4P, and TIP5P water models and are validated by carrying out detailed molecular simulations on the uranyl aqua ion, one of the most characterized actinide systems. It is shown that the force fields faithfully reproduce available experimental structural data and hydration free energies. Failure to account for solvation effects when generating PES leads to overbinding between UO2(2+) and water, resulting in incorrect hydration free energies and coordination numbers. A detailed analysis of arrangement of water molecules in the first and second solvation shell of UO2(2+) is presented. The use of a simple functional form involving the sum of Lennard-Jones + Coulomb potentials makes the new force field compatible with a large number of available molecular simulation engines and common force fields.
CALCULATION OF VISCOUS HYDRODYNAMIC FORCES ON A SHIP HULL IN OBLIQUE MOTION
Institute of Scientific and Technical Information of China (English)
QIU Lei; ZOU Zao-jian; ZHANG Xie-dong
2004-01-01
This paper focuses on computations of viscous hydrodynamic forces acting on a ship in oblique motion by solving the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations. The standard k-ε turbulence model with wall function was applied. The conservation equations were discretized by a cell-centered second-order Finite Volume Method (FVM) in a block-structured body-fitted grid and the coupling of velocity and pressure was resolved with the SIMPLE method. Computations were performed for a Wigley hull model to investigate the viscous flows around it. The results show good agreement with experimental data and more reasonable prediction of hydrodynamic forces and moments than other numerical results available.
Forces at the Main Mechanism of a Railbound Forging Manipulator
Directory of Open Access Journals (Sweden)
Florian Ion Tiberiu Petrescu
2015-12-01
Full Text Available Forging manipulators have become more prevalent in the industry today. They are used to manipulate objects to be forged. The most common forging manipulators are moving on a railway to have a greater precision and stability. They have been called the railbound forging manipulators. In this paper we determine the driving forces of the main mechanism from such manipulator. Forces diagram shows a typical forging manipulator, with the basic motions in operation process: walking, motion of the tong and buffering. The lifting mechanism consists of several parts including linkages, hydraulic drives and motion pairs. Hydraulic drives are with the lifting hydraulic cylinder, the buffer hydraulic cylinder and the leaning hydraulic cylinder, which are individually denoted by c1, c2 and c3. In this work considering that the kinematics is being solved it determines the forces of the mechanism. In the first place shall be calculated all external forces from the mechanism (The inertia forces, gravitational forces and the force of the weight of the cast part. Is then calculated all the forces from couplers.
Cavitation in Hydraulic Machinery
Energy Technology Data Exchange (ETDEWEB)
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.
Directory of Open Access Journals (Sweden)
Josip Sertić
2014-01-01
Full Text Available The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of “Milano” boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized.
Sertić, Josip; Kozak, Dražan; Samardžić, Ivan
2014-01-01
The values of reaction forces in the boiler supports are the basis for the dimensioning of bearing steel structure of steam boiler. In this paper, the application of the method of equivalent stiffness of membrane wall is proposed for the calculation of reaction forces. The method of equalizing displacement, as the method of homogenization of membrane wall stiffness, was applied. On the example of "Milano" boiler, using the finite element method, the calculation of reactions in the supports for the real geometry discretized by the shell finite element was made. The second calculation was performed with the assumption of ideal stiffness of membrane walls and the third using the method of equivalent stiffness of membrane wall. In the third case, the membrane walls are approximated by the equivalent orthotropic plate. The approximation of membrane wall stiffness is achieved using the elasticity matrix of equivalent orthotropic plate at the level of finite element. The obtained results were compared, and the advantages of using the method of equivalent stiffness of membrane wall for the calculation of reactions in the boiler supports were emphasized.
Hydraulic power take-off for wave energy systems
DEFF Research Database (Denmark)
Christensen, Georg Kronborg
2001-01-01
Investigation and laboratory experiments with a hydraulic power conversion system for converting forces from a 2.5m diamter float to extract energy from seawaves. The test rig consists of a hydraulic wave simulator and a hydraulic point absorber. The absorber converts the incomming forces...
No-Core Shell Model Calculations in Light Nuclei with Three-Nucleon Forces
Energy Technology Data Exchange (ETDEWEB)
Barrett, B R; Vary, J P; Nogga, A; Navratil, P; Ormand, W E
2004-01-08
The ab initio No-Core Shell Model (NCSM) has recently been expanded to include nucleon-nucleon (NN) and three-nucleon (3N) interactions at the three-body cluster level. Here it is used to predict binding energies and spectra of p-shell nuclei based on realistic NN and 3N interactions. It is shown that 3N force (3NF) properties can be studied in these nuclear systems. First results show that interactions based on chiral perturbation theory lead to a realistic description of {sup 6}Li.
Tang, S.; Zhang, M. H.
2014-12-01
Large-scale forcing data (vertical velocities and advective tendencies) are important atmospheric fields to drive single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulations (LES), but they are difficult to calculate accurately. The current 1-dimensional constrained variational analysis (1D CVA) method (Zhang and Lin, 1997) used by the Atmospheric Radiation Measurement (ARM) program is limited to represent the average of a sounding network domain. We extended the original 1D CVA algorithm into 3-dimensional along with other improvements, calculated gridded large-scale forcing data, apparent heating sources (Q1) and moisture sinks (Q2), and compared with 5 reanalyses: ERA-Interim, NCEP CFSR, MERRA, JRA55 and NARR for a mid-latitude spring cyclone case. The results from a case study for in March 3rd 2000 at the Southern Great Plain (SGP) show that reanalyses generally captured the structure of the mid-latitude cyclone, but they have serious biases in the 2nd order derivative terms (divergences and horizontal derivations) at regional scales of less than a few hundred kilometers. Our algorithm provides a set of atmospheric fields consistent with the observed constraint variables at the surface and top of the atmosphere better than reanalyses. The analyzed atmospheric fields can be used in SCM, CRM and LES to provide 3-dimensional dynamical forcing, or be used to evaluate reanalyses or model simulations.
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.
Method of calculation of tanks forced ventilation from the remnants of liquid products
Directory of Open Access Journals (Sweden)
С. О. Пузік
2013-07-01
Full Text Available The advantages of gasoline compared to other petroleum products in terms of feasibility of their research. Calculations of the duration of ventilation and changes in the concentration of vapors of gasoline remains in the gas space of the vertical tank with a capacity of 1000 m3 (RUS-1000. Nomogram constructed for the quantitative forecast available liquid balances petrol A-95 and the time duration ventylyaiyi RUS-1000 from the remnants of the petrol
Measurement and calculation of levitation forces between magnets and granular superconductors
Johansen, T. H.; Bratsberg, H.; Baziljevich, M.; Hetland, P. O.; Riise, A. B.
1995-01-01
Recent developments indicate that exploitation of the phenomenon of magnetic levitation may become one of the most important near-term applications of high-T(sub c) superconductivity. Because of this, the interaction between a strong permanent magnet(PM) and bulk high-T(sub c) superconductor (HTSC) is currently a subject of much interest. We have studied central features of the mechanics of PM-HTSC systems of simple geometries. Here we report experimental results for the components of the levitation force, their associated stiffness and mechanical ac-loss. To analyze the observed behavior a theoretical framework based on critical-state considerations is developed. It will be shown that all the mechanical properties can be explained consistently at a quantitative level wing a minimum of model parameters.
Energy Technology Data Exchange (ETDEWEB)
Abe, K.; Ito, K.; Suezawa, H.; Hirota, M.; Nishio, M.
1986-10-01
Conformations of a series of acyclic alcohols (CH/sub 3/CH(R)CH(OH)CH/sub 3/, CH/sub 3/CH(R)CH(OH)CH(R')CH/sub 3/, and CH/sub 3/CH(R)CH(OH)Bu/sup t/) were studied (1) by measuring vicinal H-H coupling constants (/sup 3/JH-H), (2) by lanthanoid-induced shift (LIS) analysis, (3) by molecular mechanics calculations (MM2), and (4) by ab initio (STO-3G, 4-31G geometry optimization) calculations. In the case of conformationally flexible alcohols as exemplified by 2-butanol and 3-pentanol, population of conformers determined by the LIS method do not agree with those determined by the /sup 3/JH-H, MM2, and ab initio methods. The discrepancy comes from the fact that the LIS measurement gives the most stable conformation of the alcohol in the LSR-alcohol complex and not of the free alcohol. In some flexible molecules, the most stable conformer in the complex can be different from that of the free molecule. In general, the conformational equilibrium is shifted by coordination of the shift reagent to the conformer whose alkyl chain stretches opposite to the direction of the coordination site of the shift reagent. 21 references, 1 figure, 6 tables.
SUPERENERGY-2: a multiassembly, steady-state computer code for LMFBR core thermal-hydraulic analysis
Energy Technology Data Exchange (ETDEWEB)
Basehore, K.L.; Todreas, N.E.
1980-08-01
Core thermal-hydraulic design and performance analyses for Liquid Metal Fast Breeder Reactors (LMFBRs) require repeated detailed multiassembly calculations to determine radial temperature profiles and subchannel outlet temperatures for various core configurations and subassembly structural analyses. At steady-state, detailed core-wide temperature profiles are required for core restraint calculations and subassembly structural analysis. In addition, sodium outlet temperatures are routinely needed for each reactor operating cycle. The SUPERENERGY-2 thermal-hydraulic code was designed specifically to meet these designer needs. It is applicable only to steady-state, forced-convection flow in LMFBR core geometries.
Martin, Jan M. L.
The quartic force fields of a number of small polyatomic molecules (specifically, rm H _2O, NH_2, NH_3, CH_4, BH_3, BeH_2, H_2CO, N_2O, CO_2, CS_2, OCS, H_2S, FNO, ClNO, and H_2CS) have been computed ab initio using large basis sets and augmented coupled cluster methods. It has been established throughout that harmonic and fundamental frequencies can consistently be reproduced to within about 10 cm^{ -1} of experimental using spdf basis sets, except in such inherently problematic cases as the umbrella motion in NH_3; such problems are solved by recomputing the harmonic frequencies with an spdf g basis set. Coupled cluster frequencies using small basis sets of spd quality agree surprisingly well with experiment (mean absolute error of 26 cm^ {-1}), but bond distances are generally seriously overestimated. Using spdf basis sets, they are consistently overestimated by 0.002 and 0.006-7 A for single and multiple bonds, respectively; for spdf g basis sets this drops to 0.001 and 0.003-4 A, respectively. Geometries and harmonic frequencies for highly polar fluorine compounds such as HF and FNO are qualitatively wrong unless special anion functions are added to the fluorine basis set. Anharmonicity, rovibrational coupling, and centrifugal distortion constants are consistently predicted well; the anharmonic portions of the computed force fields are probably more reliable than their experimental counterparts in many cases. Remaining errors in the computed geometries and harmonic frequencies are shown to be almost entirely due to a combination of core correlation and residual deficiencies in the electron correlation treatment. A 3-term correction for remaining basis set incompleteness to computed total atomization energies is proposed by the author, and is shown to result in mean absolute errors of as little as 0.5 kcal/mol for spdf g basis sets. Example applications on rm HCO^+, HOC^+, B_2C, BCN, and BNC testify to the predictive power of the methods used in this work.
Minomo, Kosho; Ogata, Kazuyuki
2015-01-01
We analyze $^{16}$O-$^{16}$O and $^{12}$C-$^{12}$C scattering with the microscopic coupled-channels method and investigate the coupled-channels and three-nucleon-force (3NF) effects on elastic and inelastic cross sections. In the microscopic coupled-channels calculation, the Melbourne g-matrix interaction modified according to the chiral 3NF effects is used. It is found that the coupled-channels and 3NF effects additively change both the elastic and inelastic cross sections. As a result, the coupled-channels calculation including the 3NF effects significantly improves the agreement between the theoretical results and the experimental data. The incident-energy dependence of the coupled-channels and 3NF effects is also discussed.
DEFF Research Database (Denmark)
Pøhlsgaard, Jacob; Harpsøe, Kasper; Jørgensen, Flemming Steen
2012-01-01
The binding affinity of a drug like molecule depends among other things on the availability of the bioactive conformation. If the bioactive conformation has a significantly higher energy than the global minimum energy conformation, the molecule is unlikely to bind to its target. Determination of ...... compounds generated by conformational analysis with modified electrostatics are good approximations of the conformational distributions predicted by experimental data and in simulated annealing performed in explicit solvent.......The binding affinity of a drug like molecule depends among other things on the availability of the bioactive conformation. If the bioactive conformation has a significantly higher energy than the global minimum energy conformation, the molecule is unlikely to bind to its target. Determination...... of the global minimum energy conformation and calculation of conformational penalties of binding are prerequisites for prediction of reliable binding affinities. Here, we present a simple and computationally efficient procedure to estimate the global energy minimum for a wide variety of structurally diverse...
Zhang, Gaigong; Hu, Wei; Yang, Chao; Pask, John E
2015-01-01
Recently, we have proposed the adaptive local basis set for electronic structure calculations based on Kohn-Sham density functional theory in a pseudopotential framework. The adaptive local basis set is efficient and systematically improvable for total energy calculations. In this paper, we present the calculation of atomic forces, which can be used for a range of applications such as geometry optimization and molecular dynamics simulation. We demonstrate that, under mild assumptions, the computation of atomic forces can scale nearly linearly with the number of atoms in the system using the adaptive local basis set. We quantify the accuracy of the Hellmann-Feynman forces for a range of physical systems, benchmarked against converged planewave calculations, and find that the adaptive local basis set is efficient for both force and energy calculations, requiring at most a few tens of basis functions per atom to attain accuracy required in practice. Since the adaptive local basis set has implicit dependence on a...
Nitschke, Naomi; Atkovska, Kalina; Hub, Jochen S.
2016-09-01
Molecular dynamics simulations are capable of predicting the permeability of lipid membranes for drug-like solutes, but the calculations have remained prohibitively expensive for high-throughput studies. Here, we analyze simple measures for accelerating potential of mean force (PMF) calculations of membrane permeation, namely, (i) using smaller simulation systems, (ii) simulating multiple solutes per system, and (iii) using shorter cutoffs for the Lennard-Jones interactions. We find that PMFs for membrane permeation are remarkably robust against alterations of such parameters, suggesting that accurate PMF calculations are possible at strongly reduced computational cost. In addition, we evaluated the influence of the definition of the membrane center of mass (COM), used to define the transmembrane reaction coordinate. Membrane-COM definitions based on all lipid atoms lead to artifacts due to undulations and, consequently, to PMFs dependent on membrane size. In contrast, COM definitions based on a cylinder around the solute lead to size-independent PMFs, down to systems of only 16 lipids per monolayer. In summary, compared to popular setups that simulate a single solute in a membrane of 128 lipids with a Lennard-Jones cutoff of 1.2 nm, the measures applied here yield a speedup in sampling by factor of ˜40, without reducing the accuracy of the calculated PMF.
Institute of Scientific and Technical Information of China (English)
Yong Wu; Siming He
2015-01-01
Failure of loose gully deposits under the effect of rainfall contributes to the potential risk of debris flow. In the past decades, researches on hydraulic mechanism and time-dependent characteristics of loose deposits failure are frequently reported, however adequate measures for reducing debris flow are not available practically. In this context, a time-dependent model was established to determine the changes of water table of loose deposits using hydraulic and topographic theories. In addition, the variation in water table with elapsed time was analyzed. The formulas for calculating hydrodynamic and hydrostatic pressures on each strip and block unit of deposit were proposed, and the slope stability and failure risk of the loose deposits were assessed based on the time-dependent hydraulic characteristics of established model. Finally, the failure mechanism of deposits based on infinite slope theory was illustrated, with an example, to calculate sliding force, anti-sliding force and residual sliding force applied to each slice. The results indicate that failure of gully deposits under the effect of rainfall is the result of continuously increasing hydraulic pressure and water table. The time-dependent characteristics of loose deposit failure are determined by the factors of hydraulic properties, drainage area of interest, rainfall pattern, rainfall duration and intensity.
电液伺服加载系统多余力分析%Research on Surplus Force of Electro-hydraulic Servo Loading System
Institute of Scientific and Technical Information of China (English)
韩洋; 吴晖; 曾毅; 潘阳
2016-01-01
Hydraulic cylinder position control is widely used. Electro-hydraulic servo loading system is often used to simulate the real load. This article firstly build the mathematical model of electro-hydraulic proportional position and electro-hydraulic servo loading systems. Then analyze the surplus torque generated in loading process to find out the related factors influencing the surplus torque. Finally adopt“PID+speed feed-forward compensation”to improve comprehensive performance of loading system.%液压缸位置控制广泛应用于各类液压控制系统中，常采用电液伺服加载系统模拟其运动过程中的真实负载。该文首先建立电液比例位置控制和电液伺服加载系统的数学模型；然后对加载过程中产生的多余力进行分析，找出影响多余力的相关因素；最后采用“PID+速度前馈补偿”来改善加载系统的综合性能。
Dynamic Calculation of a New Portable Hydraulic Pile Driver%一种新型便携式液压打桩机的动力学计算
Institute of Scientific and Technical Information of China (English)
张步恩
2015-01-01
In flood season,for embankment reinforcement and thepilingfor road construction and maintenance, pile driv-ing operation by machinery equipment instead of manual labor is a technological progress. At present, piling equipment has low working efficiency, heavy weight and strong labor intensity and so on, so the research on a portable hydraulic pile driver, which is used in the piling ofareas such as flood control and emergency rescue and the guardrail construction of highway and railway, will be of great significance. Under the simplified conditions, by establishing the dynamic model of portable hydraulic pile driver piling process, the acceleration of the dynamic modelsystem and the influences of the soil resistance onthe pile sinking in the piling are analyzed. And the relationship between the acceleration and the base frequency, and the influences of the soil resistance onthe pile driver are obtained, which will laya good theoretical basis for the research and development of portable hydraulic pile driver product prototype.%对于汛期的堤防加固以及公路建设与维护的打桩作业,由机械设备代替人力进行打桩作业是技术上的一次长足进步.针对目前打桩设备作业效率低、自重大及劳动强度大等缺陷,研发便携式液压打桩机用于防汛抢险、高速公路及铁路护栏建设等领域的打桩作业具有重要的意义.在简化条件下,通过建立便携式液压打桩机打桩过程的动力学模型,分析了动力学模型系统的加速度以及打桩过程中土壤阻力对沉桩的影响,得到基频与加速度的关系,土壤阻力对打桩机的影响,为研发便携式液压打桩机产品样机奠定良好的理论基础.
Institute of Scientific and Technical Information of China (English)
袁良正; 贾金洁
2016-01-01
Exampled with a large scale of coal-to-natural gas plant, hydraulic and purging parameters for high pressure and superheated steam pipe network were studied in this article. By using chemical process simulation software ASPEN HYSIS, the model of steam pipeline net was established and then it was calculated, with which the method based on quantitative analysis for calculating steam purging parameters was found.%以某大型煤制天然气项目为例，对高压过热蒸汽管网的水力学及吹扫参数进行研究。采用化工流程模拟软件ASPEN HYSYS对蒸汽管网进行建模计算，找到了一种定量分析计算蒸汽吹扫参数的方法。
Ahlstrand, Emma; Hermansson, Kersti; Friedman, Ran
2017-03-24
Zinc plays important roles in structural stabilization of proteins, enzyme catalysis, and signal transduction. Many Zn binding sites are located at the interface between the protein and the cellular fluid. In aqueous solutions, Zn ions adopt an octahedral coordination, while in proteins zinc can have different coordinations, with a tetrahedral conformation found most frequently. The dynamics of Zn binding to proteins and the formation of complexes that involve Zn are dictated by interactions between Zn and its binding partners. We calculated the interaction energies between Zn and its ligands in complexes that mimic protein binding sites and in Zn complexes of water and one or two amino acid moieties, using quantum mechanics (QM) and molecular mechanics (MM). It was found that MM calculations that neglect or only approximate polarizability did not reproduce even the relative order of the QM interaction energies in these complexes. Interaction energies calculated with the CHARMM-Drude polarizable force field agreed better with the ab initio results, although the deviations between QM and MM were still rather large (40-96 kcal/mol). In order to gain further insight into Zn-ligand interactions, the free energies of interaction were estimated by QM calculations with continuum solvent representation, and we performed energy decomposition analysis calculations to examine the characteristics of the different complexes. The ligand-types were found to have high impact on the relative strength of polarization and electrostatic interactions. Interestingly, ligand-ligand interactions did not play a significant role in the binding of Zn. Finally, analysis of ligand exchange energies suggests that carboxylates could be exchanged with water molecules, which explains the flexibility in Zn binding dynamics. An exchange between carboxylate (Asp/Glu) and imidazole (His) is less likely.
Energy Technology Data Exchange (ETDEWEB)
Bauer, C.
2001-07-01
The objective of this study is the development of an algorithm enabling coupling of nonmatching computational grids to carry out calculations of an unsteady flow through a hydraulic axial turbine with reference to interaction between stator and rotor. The algorithm should offer the possibility to operate the computational grids in a fixed position relative to each other as well as in relative movement. Furthermore, the calculation should be feasible with separate grids in parallel and different frames of reference. Employing selected examples this method is investigated in detail the results are compared with performed measurements. The unsteady numerical examination of the coupling process is carried out with different examples; especially the interaction effects between stator, rotor and draft tube of a hydraulic axial turbine are observed. In addition, the effect of tip clearance of the mean flow is described. Extensive model tests using the axial turbine have been performed at the Institute for Fluid Mechanics and Hydraulic Machinery, IHS. Flow time dependent velocities have been measured with a Laser Doppler Velocimeter placed at midspan of the blading. Periodical changes in static pressure have been recorded at different locations near the wall of the turbine casing. These measurements serve as reference for the comparison with results derived from the unsteady calculations. The confrontation of the time-dependent fluctuations of the flow quantities and the calculation of the efficiency of the turbine resulting from the simulation results allow a comparison in absolute terms. (orig.) [German] Fuer die instationaere Berechnung einer hydraulischen Axialturbine unter Beruecksichtigung der Interaktion zwischen Leit- und Laufrad wird ein Algorithmus zum Koppeln von nichtpassenden Berechnungsnetzen entwickelt. Diese Berechnungsnetze sollen zueinander ortsfest sein oder auch eine Relativbewegung zueinander haben koennen. Sie sollen ausserdem und in unterschiedlichen
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.
Energy Technology Data Exchange (ETDEWEB)
Domingos, Douglas Borges; Silva, Antonio Teixeira e; Umbehaun, Pedro Ernesto; Silva, Jose Eduardo Rosa da; Conti, Thadeu das Neves; Yamaguchi, Mitsuo [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)], e-mail: douglasborgesdomingos@yahoo.com.br
2009-07-01
Neutronic, thermal-hydraulics and accident analysis calculations were developed to estimate the safety of an irradiation device placed in the IEA-R1 reactor core. The irradiation device will be used to receive miniplates of U{sub 3}O{sub 8}-Al e U{sub 3}Si{sub 2}-Al dispersion fuels, LEU type (19.9% of {sup 235}U), with uranium densities of, respectively, 3.0 gU/cm{sup 3} and 4.8gU/cm{sup 3}. The fuel miniplates will be irradiated to nominal {sup 235}U burnup levels of 50% and 80%, in order to qualify the above high-density dispersion fuels to be used in the Brazilian Multipurpose Reactor, now in the conception phase. For the neutronic calculation, the computer code CITATION was utilized. The computer code FLOW was used to calculate the coolant flow rate in the irradiation device, allowing the determination of the fuel miniplate temperatures with the computer model MTRCR-IEA-R1. A postulated Loss of Coolant Accident (LOCA) was analyzed with the computer codes LOSS and TEMPLOCA, allowing the calculation of the fuel miniplate temperatures after the reactor pool draining. The calculations showed that the irradiation of the fuel miniplates will happen without any adverse consequence in the IEA-R1 reactor. (author)
Institute of Scientific and Technical Information of China (English)
ChenJing
2004-01-01
Until recently the hydrogen molecule structural parameters are calculated with the methods of quantum mechanics. To achieve results close to experimental values, the wave function used is complicated and has no clear physical meaning. Because the distribution of the electron probability density is a statistical rule, the macro-time has actually been used in the concept on a electron cloud graph. Here are obtained three formulas with a classical mechanics method on the bond-length re , bond-energy De and force constant k of the ground state hydrogen molecule, which have a clear physical meaning but no artificial parameters, and compared with experimental values, the relative errors are respectively less than 1% , 2% and 4% .
Minh, David D L
2015-01-01
A binding potential of mean force (BPMF) is a free energy of noncovalent association in which one binding partner is flexible and the other is rigid. I have developed a method to calculate BPMFs for protein-ligand systems. The method is based on replica exchange sampling from multiple thermodynamic states at different temperatures and protein-ligand interaction strengths. Protein-ligand interactions are represented by interpolating precomputed electrostatic and van der Waals grids. Using a simple estimator for thermodynamic length, thermodynamic states are initialized at approximately equal intervals. The method is demonstrated on the Astex diverse set, a database of 85 protein-ligand complexes relevant to pharmacy or agriculture. Fifteen independent simulations of each complex were started using poses from crystallography, docking, or the lowest-energy pose observed in the other simulations. Benchmark simulations completed within three days on a single processor. Overall, protocols initialized using the ther...
Lenaerts, G; Bartels, W; Gelaude, F; Mulier, M; Spaepen, A; Van der Perre, G; Jonkers, I
2009-06-19
Hip loading affects the development of hip osteoarthritis, bone remodelling and osseointegration of implants. In this study, we analyzed the effect of subject-specific modelling of hip geometry and hip joint centre (HJC) location on the quantification of hip joint moments, muscle moments and hip contact forces during gait, using musculoskeletal modelling, inverse dynamic analysis and static optimization. For 10 subjects, hip joint moments, muscle moments and hip loading in terms of magnitude and orientation were quantified using three different model types, each including a different amount of subject-specific detail: (1) a generic scaled musculoskeletal model, (2) a generic scaled musculoskeletal model with subject-specific hip geometry (femoral anteversion, neck-length and neck-shaft angle) and (3) a generic scaled musculoskeletal model with subject-specific hip geometry including HJC location. Subject-specific geometry and HJC location were derived from CT. Significant differences were found between the three model types in HJC location, hip flexion-extension moment and inclination angle of the total contact force in the frontal plane. No model agreement was found between the three model types for the calculation of contact forces in terms of magnitude and orientations, and muscle moments. Therefore, we suggest that personalized models with individualized hip joint geometry and HJC location should be used for the quantification of hip loading. For biomechanical analyses aiming to understand modified hip joint loading, and planning hip surgery in patients with osteoarthritis, the amount of subject-specific detail, related to bone geometry and joint centre location in the musculoskeletal models used, needs to be considered.
Toyokawa, Masakazu; Matsumoto, Takuma; Minomo, Kosho; Ogata, Kazuyuki; Kohno, Michio
2015-01-01
We investigate the effects of chiral three-nucleon force (3NF) on proton scattering at 65 MeV and $^{4}$He scattering at 72 MeV/nucleon from heavier targets, using the standard microscopic framework composed of the Brueckner-Hartree-Fock (BHF) method and the $g$-matrix folding model. For nuclear matter, the $g$ matrix is evaluated from chiral two-nucleon force (2NF) of N$^{3}$LO and chiral 3NF of NNLO by using the BHF method. Since the $g$ matrix thus obtained is numerical and nonlocal, an optimum local form is determined from the on-shell and near-on-shell components of $g$ matrix that are important for elastic scattering. For elastic scattering, the optical potentials are calculated by folding the local chiral $g$ matrix with projectile and target densities. This microscopic framework reproduces the experimental data without introducing any adjustable parameter. Chiral-3NF effects are small for proton scattering, but sizable for $^{4}$He scattering at middle angles where the data are available. Chiral 3NF, ...
Guo, Guang-Jun; Li, Meng; Zhang, Yi-Gang; Wu, Chang-Hua
2009-11-28
By performing constrained molecular dynamics simulations in the methane-water system, we successfully calculated the potential of mean force (PMF) between a dodecahedral water cage (DWC) and dissolved methane for the first time. As a function of the distance between DWC and methane, this is characterized by a deep well at approximately 6.2 A and a shallow well at approximately 10.2 A, separated by a potential barrier at approximately 8.8 A. We investigated how the guest molecule, cage rigidity and the cage orientation affected the PMF. The most important finding is that the DWC itself strongly adsorbs methane and the adsorption interaction is independent of the guests. Moreover, the activation energy of the DWC adsorbing methane is comparable to that of hydrogen bonds, despite differing by a factor of approximately 10% when considering different water-methane interaction potentials. We explain that the cage-methane adsorption interaction is a special case of the hydrophobic interaction between methane molecules. The strong net attraction in the DWC shell with radii between 6.2 and 8.8 A may act as the inherent driving force that controls hydrate formation. A cage adsorption hypothesis for hydrate nucleation is thus proposed and discussed.
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…
SITMILARITY LAW FOR HYDRAULIC DISTORTED MODEL
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
Newton's general similarity criterion was applied to the distorted model. The results for the similarities of gravity force, drag force and pressure force are identical with those derived from relevant differential equations of fluid flow. And the selected limits of the distorted ratio were studied and the simulation of roughness coefficient of distorted model was conducted by means of hydraulic test.
Institute of Scientific and Technical Information of China (English)
李昊; 孙宝江; 高永海; 王金堂; 王宁
2013-01-01
深水控制泥浆帽钻井技术可以应对严重漏失地层和高压、高含硫地层的钻井问题,但钻井水力参数的设计与计算较为困难.为此,结合深水钻井工艺流程,建立了深水控制泥浆帽钻井井底压力计算模型,给出了深水钻井不同工况下的钻井液密度确定准则和钻井液当量循环密度计算方法,并基于井筒内循环压耗分析得到了水面泵和水下泵的泵压计算方法；针对严重漏失地层和高压、高含硫地层的井筒压力分布特点,给出了该工况下的泥浆帽高度计算方法；结合井眼清洁准则和漏失量与漏失压差的关系,给出了牺牲流体排量计算方法,并以此为基础提出了深水控制泥浆帽钻井水力参数设计流程.以一口深水井为例,对控制泥浆帽钻井水力参数进行了算例分析,结果表明:泥浆帽高度主要由井底压力的大小决定,钻井液密度与排量的大小可对其产生一定影响,所以通过调节泥浆帽高度可以控制井筒压力.%Deepwater control mud cap drilling is an advanced technology to deal with thief zone,highpressure and high sulfur-bearing formation,but its drilling hydraulic parameters design and calculation are more complex.According to the drilling process in deepwater,the calculation model of BHP for deepwater control mud cap drilling was established.The guidelines for determining drilling fluid density under different conditions and calculation method of ECD were proposed,based on the analysis of circulating pressure loss,the calculating methods for pump pressure were put forward at subsea and surface respectively.The calculation method of mud cap height was proposed according to the characteristics of wellbore pressure distribution in thief zone,high pressure and high sulfur-bearing formation.Based on the wellbore cleaning rule and the relationship between lost amount and lost pressure differential,the calculation method of sacrificed flow rate was proposed
Energy Technology Data Exchange (ETDEWEB)
Vasiliev, A., E-mail: vasil@ibrae.ac.ru [Nuclear Safety Institute (IBRAE), B. Tulskaya 52, 115191 Moscow (Russian Federation); Stuckert, J., E-mail: juri.stuckert@kit.edu [Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)
2015-03-15
Highlights: • Modeling of processes in porous debris regions. • Analysis of coolability of massive debris bed. • Complexity of simulation of flow regime near boiling curve. - Abstract: The thermal hydraulic and SFD (Severe Fuel Damage) best estimate computer modeling code SOCRAT/V3 was used for the post-test analysis of the QUENCH-17 experiment performed at KIT on January 2013. The objective of this test was to examine the formation of a debris bed inside the completely oxidized region of the bundle without melt formation and to investigate the coolability behavior during the reflood. The test bundle for QUENCH-17 test was intentionally changed in comparison to basic QUENCH bundles (usually 21 heated rod simulators) with the emphasis to investigate debris behavior phenomena. Only 12 periphery fuel rod simulators were heated by centerline tungsten heaters. 9 unheated fuel rod simulators were located in the inner part of the test bundle. This is why the massive porous debris formation in the inner part of the bundle was not influenced by the presence of tungsten heaters. The QUENCH-17 test conditions simulated a hypothetical scenario of nuclear power plant severe accident sequence with debris bed formation in which the overheated up to 1800 K core would be flooded from the bottom by ECCS (Emergency Core Cooling System). The QUENCH-17 test included the following phases: (1) heat-up phase (heat-up rate up to 0.25 K/s); (2) oxidation phase (the cladding temperature about 1800 K in hottest region, steam mass flow rate 2 g/s); (3) bottom flood phase (characteristic cooling time about 600 s, water mass flow rate 10 g/s). SOCRAT/V3 computer modeling code was used for calculation of basic thermal hydraulic, oxidation and thermal mechanical behavior during all phases of the experiment. The calculated results are in a good agreement with experimental data which justifies the adequacy of modeling capabilities of SOCRAT code system.
Sweere, Augustinus J M; Fraaije, Johannes G E M
2017-05-09
We have calculated the excess free energy of mixing of 1053 binary mixtures with the OPLS-AA force field using two different methods: thermodynamic integration (TI) of molecular dynamics simulations and the Pair Configuration to Molecular Activity Coefficient (PAC-MAC) method. PAC-MAC is a force field based quasi-chemical method for predicting miscibility properties of various binary mixtures. The TI calculations yield a root mean squared error (RMSE) compared to experimental data of 0.132 kBT (0.37 kJ/mol). PAC-MAC shows a RMSE of 0.151 kBT with a calculation speed being potentially 1.0 × 10(4) times greater than TI. OPLS-AA force field parameters are optimized using PAC-MAC based on vapor-liquid equilibrium data, instead of enthalpies of vaporization or densities. The RMSE of PAC-MAC is reduced to 0.099 kBT by optimizing 50 force field parameters. The resulting OPLS-PM force field has a comparable accuracy as the OPLS-AA force field in the calculation of mixing free energies using TI.
Knipfer, T; Fei, J; Gambetta, G A; Shackel, K A; Matthews, M A
2014-10-21
The cell-pressure-probe is a unique tool to study plant water relations in-situ. Inaccuracy in the estimation of cell volume (νo) is the major source of error in the calculation of both cell volumetric elastic modulus (ε) and cell hydraulic conductivity (Lp). Estimates of νo and Lp can be obtained with the pressure-clamp (PC) and pressure-relaxation (PR) methods. In theory, both methods should result in comparable νo and Lp estimates, but this has not been the case. In this study, the existing νo-theories for PC and PR methods were reviewed and clarified. A revised νo-theory was developed that is equally valid for the PC and PR methods. The revised theory was used to determine νo for two extreme scenarios of solute mixing between the experimental cell and sap in the pressure probe microcapillary. Using a fully automated cell-pressure-probe (ACPP) on leaf epidermal cells of Tradescantia virginiana, the validity of the revised theory was tested with experimental data. Calculated νo values from both methods were in the range of optically determined νo (=1.1-5.0nL) for T. virginiana. However, the PC method produced a systematically lower (21%) calculated νo compared to the PR method. Effects of solute mixing could only explain a potential error in calculated νo of cell turgor) of 19%, which is a fundamental parameter in calculating νo. It followed from the revised theory that the ratio of ΔV/ΔP was inversely related to the solute reflection coefficient. This highlighted that treating the experimental cell as an ideal osmometer in both methods is potentially not correct. Effects of non-ideal osmotic behavior by transmembrane solute movement may be minimized in the PR as compared to the PC method.
2011-01-01
Finite element method analysis of main lines of hydraulic central loading system installation expansion loops mounted on product and chemical tankers has been presented in the paper. The axial forces problem in installations mounted along the ship's open decks executed from hull deformations on waves and thermal stresses is given. Use of "U" type expansion loops is described. Results of forces in anchor points and stresses of Mises due to expansion loop deformations are shown. Calculations we...
Force Calculation of Turret FPSO Single Point Mooring System%转塔式FPSO单点系泊系统受力计算方法
Institute of Scientific and Technical Information of China (English)
李伟峰; 史国友; 李伟; 杨家轩
2012-01-01
According to the national relative criterions and standards, some calculations are made on wind force, current force as well as wave force which affect FPSO single point mooring system. Then the force conditions of mooring chains of the mooring system are analyzed. Hie force calculation modal of mooring chains is established, making use of the static method to solve the dynamic force of anchoring chain problem, which provides a simple but effective method to check the turret FPSO single point mooring system. Finally, taking the "South Sea Development" FPSO as an example to check the correction of the method, and it is verified that the calculation results are very close to the actual conditions.%依据国家有关标准及相关规范,计算了影响FPSO单点系泊系统的风作用力、流作用力和波浪作用力,分析了系泊系统各锚链的受力情况；建立了锚链受力计算模型,将动态锚链受力问题通过静态的计算方法予以核算,为转塔式FPSO单点系泊系统提供了一种简单有效的核算方法.以“南海开拓”号FPSO为例进行验算,计算结果与实际情况基本相符.
Institute of Scientific and Technical Information of China (English)
季雅宙
2013-01-01
Coal mine safety rules show: we must establish and improve dustproof and water supply system in the mine well. Based on the comprehensive study and analysis on the status of water supply system in Tangshan Mining Company Tieyi District and the reconstruction plan of water supply system, this paper used the pipe network hydraulic calculation theory to calculate the existing and new water supply system to build and improve the dustproof and water supply system and ensure safety of mine.% 煤矿安全规程规定：矿井必须建立完善的防尘供水系统。本文通过对唐山矿业公司铁一区供水系统的现状及下步供水系统改造计划的综合研究、分析，利用管网水力计算理论对铁一区生产区域现有和新建供水系统进行计算校核，确保铁一区建立完善的防尘供水系统，保证矿井的安全生产。
废液处理系统冷却器热工水力计算研究%The Research of Thermal-hydraulic Calculation for Waste Processing System Cooler
Institute of Scientific and Technical Information of China (English)
孙圣权; 刘宇昊; 高峰; 马贞钦; 陈先林; 徐江
2016-01-01
As one of the key equipment is cooler radioactive in waste processing system,which will determine whether the system is capable of stable operation. In this paper, a mathematical model based on thermal-hydraulic calculation,by calculation and verification,to ensure that the system can meet the key equipment cooler design and use requirements,this method is similar to the equipment design and testing provided useful experience.%冷却器作为放射性废液处理系统中的关键设备之一，直接决定了系统是否能够稳定运行，本文建立基于热工水力计算的数学模型，通过计算与校核，确保系统关键设备冷却器能够满足设计和使用要求，该方法为类似设备的设计和试验提供了可借鉴的经验。
Institute of Scientific and Technical Information of China (English)
吕坤
2012-01-01
Water hammer of cavities collapsing is harm for long distance and large water pi pel inc. water hammer boost is dozens of times more than the ordinary water hammer. Al present mainly through hydraulic calculation model to predict ihe pipeline pressure, there are two kindx of models. the difference is that whether can reflect the flow and calculate pressure. by ram combing theory and practice conelusion, consider the water hammer of cavities collapsing model reflects (he actual situation.%断流弥合水锤对于长距离的大型输水管道来说危害极大,水锤升压是普通水锤的数十倍.目前主要通过水力计算模型来预测管道压力情况,王要存在两种模型,其区别在于是否反应出断流现象及计算出断流后的压力.通过理论结合实践得出结论,考虑断流弥合水锤的计算模型更反映出实际情况.
Pankoke, S.; Buck, B.; Woelfel, H. P.
1998-08-01
Long-term whole-body vibrations can cause degeneration of the lumbar spine. Therefore existing degeneration has to be assessed as well as industrial working places to prevent further damage. Hence, the mechanical stress in the lumbar spine—especially in the three lower vertebrae—has to be known. This stress can be expressed as internal forces. These internal forces cannot be evaluated experimentally, because force transducers cannot be implementated in the force lines because of ethical reasons. Thus it is necessary to calculate the internal forces with a dynamic mathematical model of sitting man.A two dimensional dynamic Finite Element model of sitting man is presented which allows calculation of these unknown internal forces. The model is based on an anatomic representation of the lower lumbar spine (L3-L5). This lumber spine model is incorporated into a dynamic model of the upper torso with neck, head and arms as well as a model of the body caudal to the lumbar spine with pelvis and legs. Additionally a simple dynamic representation of the viscera is used. All these parts are modelled as rigid bodies connected by linear stiffnesses. Energy dissipation is modelled by assigning modal damping ratio to the calculated undamped eigenvalues. Geometry and inertial properties of the model are determined according to human anatomy. Stiffnesses of the spine model are derived from static in-vitro experiments in references [1] and [2]. Remaining stiffness parameters and parameters for energy dissipation are determined by using parameter identification to fit measurements in reference [3]. The model, which is available in 3 different postures, allows one to adjust its parameters for body height and body mass to the values of the person for which internal forces have to be calculated.
Institute of Scientific and Technical Information of China (English)
王兴洲; 徐超; 何永森
2001-01-01
In order to research into more novel and reliable full-hydraulic automatic reversing device for booster and the methods of parameters calculation related to the reversal frequency of booster, on the basis of discussing super high pressure water jet generators, including the working principle of booster, and making an all-round analysis of the automatic reversing devices for all types of boosters at home and abroad, a classification method of existent automatic reversing device for boosters is put forward. This classification method is definite in concept and helpful to specify the design of thistype devices. A full-hydraulic automatic revesing device, which has many advantages such as specific structure, simplified system, lower noise level, less faults, and so on, is proposed. The experiment has shown that the calculation and the new device used in the design of water jet cutting machines have simplified the structure of water jet generators and improved their reliability. It plays a positive and impellent role in improving the quality of super high pressure water jet cutting machines and in the development of water jet cutting technology.%为了研究更为新颖可靠的增压器全液压自动换向装置和与增压器换向频率有关的参数计算方法，对超高压水射流发生器及增压器的工作原理进行了分析，研制了1种对现行增压器自动换向装置的分类方法及具有结构独特、系统简单、机械噪音小、故障率低等优点的全液压自动换向装置.实验结果表明：该分类方法概念明确，有利于规范此类装置的设计；将计算方法和新装置应用于水射流切割机产品的设计中，简化了水射流发生器结构，提高了其工作的可靠性，对提高超高压水射流切割机产品质量和促进水射流切割技术的发展起到了积极的推动作用.
Modeling and Simulation of Hydraulic Engine Mounts
Institute of Scientific and Technical Information of China (English)
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.
Furuya, M.
2006-01-01
Currently, 434 nuclear power plants are in operation worldwide. 21% of them are known as Boiling Water Reactors (BWRs). These BWRs have pumps that cool their reactor cores (the forced circulation BWRs). In the design of new BWRs, ways to cool the core by a natural circulation flow, without pumps, al
Furuya, M.
2006-01-01
Currently, 434 nuclear power plants are in operation worldwide. 21% of them are known as Boiling Water Reactors (BWRs). These BWRs have pumps that cool their reactor cores (the forced circulation BWRs). In the design of new BWRs, ways to cool the core by a natural circulation flow, without pumps,
Furuya, M.
2006-01-01
Currently, 434 nuclear power plants are in operation worldwide. 21% of them are known as Boiling Water Reactors (BWRs). These BWRs have pumps that cool their reactor cores (the forced circulation BWRs). In the design of new BWRs, ways to cool the core by a natural circulation flow, without pumps, al
Bandura, A V; Sofo, J O; Kubicki, J D
2006-04-27
Plane-wave density functional theory (DFT-PW) calculations were performed on bulk SnO2 (cassiterite) and the (100), (110), (001), and (101) surfaces with and without H2O present. A classical interatomic force field has been developed to describe bulk SnO2 and SnO2-H2O surface interactions. Periodic density functional theory calculations using the program VASP (Kresse et al., 1996) and molecular cluster calculations using Gaussian 03 (Frisch et al., 2003) were used to derive the parametrization of the force field. The program GULP (Gale, 1997) was used to optimize parameters to reproduce experimental and ab initio results. The experimental crystal structure and elastic constants of SnO2 are reproduced reasonably well with the force field. Furthermore, surface atom relaxations and structures of adsorbed H2O molecules agree well between the ab initio and force field predictions. H2O addition above that required to form a monolayer results in consistent structures between the DFT-PW and classical force field results as well.
Yaqoob, M.A.; Rooij, de M.B.; Schipper, D.J.
2013-01-01
The adhesion force due to capillary interaction between two hydrophilic surfaces is strongly dependent on the partial pressure of water and is often calculated using the Kelvin equation. The validity of the Kelvin equation is questionable at low relative humidity (RH) of water, like in high vacuum a
Institute of Scientific and Technical Information of China (English)
和东平; 韩贺永; 黄庆学; 王君; 张晓民; 李佳
2016-01-01
The electro-hydraulic position servo control model and electro-hydraulic force servo control model are es-tablished respectively based on AMEsim,and the dynamic simulation is carried out.The position step response curve and the force step response curve are obtained by adjusting the appropriate PID parameters and the advanta-ges and the disadvantages of the two control methods have been given.And the double loop limit amplitude transfer strategy of the full-hydraulic leveler is further put forward,when a loop is in the working state and another loop is al-ways in the saturated state through the working of limiter,the smooth transition of the double loop is ultimately realized.The transfer strategy which whether it is that the position closed loop turns to force loop or that force closed loop turns to position closed loop can be achieved smoothly through simulation analysis.At last,the feasibility and effec-tiveness of the proposed transfer strategy is verified by using the method of master slave synchronization in the two-cylinder synchronous test rig at the laboratory,and the transfer strategy has important guiding significance to the production.%基于AMEsim分别建立了全液压矫直机电液位置伺服控制模型和电液力伺服控制模型，并分别对其进行了动态仿真研究，通过调整合适的PID参数，得到了位置阶跃响应曲线和力阶跃响应曲线，明确了二者控制的优缺点。并且进一步提出了全液压矫直机的双环限幅转换策略，通过限幅器的作用，当一个环处于工作状态的时候另一个环始终处于饱和状态，最终实现双环的平稳转换。通过仿真分析，该转换策略不管是位置闭环向力闭环转换还是力闭环向位置闭环转换都可以实现平稳转换。最后在实验室两缸同步实验台上用主从同步方式验证该转换策略的可行性和有效性，该转换策略对现实的生产具有重要的指导意义。
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.
Electro Hydraulic Hitch Control
DEFF Research Database (Denmark)
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...
2006-01-01
Currently, 434 nuclear power plants are in operation worldwide. 21% of them are known as Boiling Water Reactors (BWRs). These BWRs have pumps that cool their reactor cores (the forced circulation BWRs). In the design of new BWRs, ways to cool the core by a natural circulation flow, without pumps, also called natural circulation BWRs, are being considered. A possible disadvantage of natural circulation BWRs might be their susceptibility to instabilities, which could then lead to both flow and ...
I. I. Sergey; E. G. Ponomarenko; W. M. Sammur; P. I. Klimkovich
2005-01-01
The paper contains description of a simplified method for calculating closing-in of switch-gear flexible buses at short circuit. The developed method is based on integral and energy principles of mechanics. In order to increase accuracy of the calculation corrections factors are introduced in an explicit formula for calculation of maximum horizontal deviations. These factors have been obtained with the help of a computer program that realized numerical method for calculating closing-in of wi...
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...
Fu, Haohao; Shao, Xueguang; Chipot, Christophe; Cai, Wensheng
2016-08-09
Proper use of the adaptive biasing force (ABF) algorithm in free-energy calculations needs certain prerequisites to be met, namely, that the Jacobian for the metric transformation and its first derivative be available and the coarse variables be independent and fully decoupled from any holonomic constraint or geometric restraint, thereby limiting singularly the field of application of the approach. The extended ABF (eABF) algorithm circumvents these intrinsic limitations by applying the time-dependent bias onto a fictitious particle coupled to the coarse variable of interest by means of a stiff spring. However, with the current implementation of eABF in the popular molecular dynamics engine NAMD, a trajectory-based post-treatment is necessary to derive the underlying free-energy change. Usually, such a posthoc analysis leads to a decrease in the reliability of the free-energy estimates due to the inevitable loss of information, as well as to a drop in efficiency, which stems from substantial read-write accesses to file systems. We have developed a user-friendly, on-the-fly code for performing eABF simulations within NAMD. In the present contribution, this code is probed in eight illustrative examples. The performance of the algorithm is compared with traditional ABF, on the one hand, and the original eABF implementation combined with a posthoc analysis, on the other hand. Our results indicate that the on-the-fly eABF algorithm (i) supplies the correct free-energy landscape in those critical cases where the coarse variables at play are coupled to either each other or to geometric restraints or holonomic constraints, (ii) greatly improves the reliability of the free-energy change, compared to the outcome of a posthoc analysis, and (iii) represents a negligible additional computational effort compared to regular ABF. Moreover, in the proposed implementation, guidelines for choosing two parameters of the eABF algorithm, namely the stiffness of the spring and the mass
Institute of Scientific and Technical Information of China (English)
王美香
2014-01-01
提出了一种新的给水管网水力计算方法．该方法对给水管网系统的节点流量连续性方程进行重新构造，用改进的Cholesky分解方法对重新构造的矩阵进行三角分解，然后使用预处理共轭梯度法求解．经用供水管网模型进行验证并与EPANET软件的计算结果进行比较，结果表明：该算法共迭代5次，用时0．102 s，与EPANET混合节点-环方法的求解精度和速度非常接近，且弥补了EPA-NET软件的应用缺陷，可用于求解大型城市的给水管网系统．%A calculation method of water distribution network hydraulic was proposed.The nodes flow conti-nuity equation of water distribution system was reconstructed,the reconstructed matrix was decomposed tri-angularly by a modified Cholesky decomposition method,and thus it was suitable for the use of precondi-tioned conjugate gradient method.It was tested by the model of water distribution network(WDN)hydrau-lic.Compared with calculation result of EPANET software,the proposed algorithm does total iteration five times in 0.1 02 s,which closed to the result of mixed node-ring method used in EPANET software in the as-pect of accuracy and speed.The proposed algorithm overcame the defects of EPANET software,which could be used to solve large-scale urban water supply network system.
Calculation of the effect of tip geometry on noncontact atomic force microscopy using a qPlus sensor
Directory of Open Access Journals (Sweden)
Julian Stirling
2013-01-01
Full Text Available In qPlus atomic force microscopy the tip length can in principle approach the length of the cantilever. We present a detailed mathematical model of the effects this has on the dynamic properties of the qPlus sensor. The resulting, experimentally confirmed motion of the tip apex is shown to have a large lateral component, raising interesting questions for both calibration and force-spectroscopy measurements.
Singular perturbation approach for control of hydraulically driven flexible manipulator
Institute of Scientific and Technical Information of China (English)
LI Guang; WU Min
2005-01-01
The hydraulic flexible manipulator system is divided into two parts: flexible arm dynamics and hydraulic servomechanism, a driving Jacobian is derived to connect these two parts. Taking hydraulic actuator force as virtual input, a singular perturbed composite model is formulated and used to design composite controllers for the flexible link, in which the slow subsystem controller dominates the trajectory tracking, and then a fast controller is designed to damp out the vibration of the flexible structure. Moreover, the backstepping technique is applied to regulate the spool position of a hydraulic valve to provide the required force. Simulation results are provided to show the effectiveness of the presented approach.
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.
Gusso, André; Burnham, Nancy A.
2016-09-01
It has long been recognized that stochastic surface roughness can considerably change the van der Waals (vdW) force between interacting surfaces and particles. However, few analytical expressions for the vdW force between rough surfaces have been presented in the literature. Because they have been derived using perturbative methods or the proximity force approximation the expressions are valid when the roughness correction is small and for a limited range of roughness parameters and surface separation. In this work, a nonperturbative approach, the effective density method (EDM) is proposed to circumvent some of these limitations. The method simplifies the calculations of the roughness correction based on pairwise summation (PWS), and allows us to derive simple expressions for the vdW force and energy between two semispaces covered with stochastic rough surfaces. Because the range of applicability of PWS and, therefore, of our results, are not known a priori, we compare the predictions based on the EDM with those based on the multilayer effective medium model, whose range of validity can be defined more properly and which is valid when the roughness correction is comparatively large. We conclude that the PWS can be used for roughness characterized by a correlation length of the order of its rms amplitude, when this amplitude is of the order of or smaller than a few nanometers, and only for typically insulating materials such as silicon dioxide, silicon nitride, diamond, and certain glasses, polymers and ceramics. The results are relevant for the correct modeling of systems where the vdW force can play a significant role such as micro and nanodevices, for the calculation of the tip-sample force in atomic force microscopy, and in problems involving adhesion.
Project W-320, 241-C-106 sluicing piping calculations, Volume 7
Energy Technology Data Exchange (ETDEWEB)
Bailey, J.W.
1998-07-29
The object of this report is to calculate the hydraulic forces imposed at the sluicer nozzle. This is required by Project W-320 waste retrieval for tank 241-C-106. The method of analysis used is Bernoulli`s momentum equation for stead flow.
Hydraulic resistance to movement of a drill suspended by a cable in a bore-hole in travels
Vasiliev,N.I./Kudryashov, B.B.
2002-01-01
Equations are given for calculation of the hydraulic resistance force to movement of a drill suspended by cable and the speed of its movement as a function of the dimension and mass of the drill and properties of the hole liquid. The most significant factor influencing the hydraulic resistance during drill movement in the hole is the radial clearance between the drill and bore-hole walls. The methods of experimental study of the drill movement on the laboratory stand are described. The result...
Catalina, Adrian V.; Stefanescu, Doru M.; Sen, Subhayu
2000-01-01
The distribution of insoluble particles in a metal casting depends primarily on the interaction of the particles with the solid/liquid interface (SLI) during the solidification process. The balance of the forces acting on the particle essentially determines whether a particle will be engulfed or pushed by the SLI. An important component of this force balance is the drag force generated by the particle motion in front of the SLI. Previously developed mathematical models for particle/SLI interaction made use of steady-state solutions of this force provided by the lubrication theory. However, our numerical model based on the SLI tracking approach shows that the steady-state approach is inappropriate to model the interaction process and that at steady-state the theoretical solution underestimates the drag force. It was found that regression analysis of steady-state numerical solutions for cylindrical particles moving normal to a flat SLI gives a relationship of the form: Abstract The distribution of insoluble particles in a metal casting depends primarily on the interaction of the particles with the solid/liquid interface (SLI) during the solidification process. The balance of the forces acting on the particle essentially determines whether a particle will be engulfed or pushed by the SLI. An important component of this force balance is the drag force generated by the particle motion in front of the SLI. Previously developed mathematical models for particle/SLI interaction made use of steady-state solutions of this force provided by the lubrication theory. However, our numerical model based on the SLI tracking approach shows that the steady-state approach is inappropriate to model the interaction process and that at steady-state the theoretical solution underestimates the drag force. It was found that regression analysis of steady-state numerical solutions for cylindrical particles moving normal to a flat SLI gives a relationship of the form: F(sub D, sup num) =sqoare
Internal Force Calculation of Long Cantilever Traffic Deck Slab%长悬臂行车道板的内力计算
Institute of Scientific and Technical Information of China (English)
孙立刚
2012-01-01
采用沙柯公式、贝达巴赫公式和Ansys计算分析公路桥梁长悬臂行车道板的内力,总结了计算方法,对设计工作具有一定的参考价值。%Internal force of long cantilever traffic deck slab of highway bridge is calculated and analyzed by the adoption of Sawko formula,Baider Bahkt formula,and Ansys.Calculation methods are summarized which have certain reference value for design effort.
1984-05-01
HDL technical report). H. E. Brandt, Bremsstrahlung Recoil Force on the Third-Order Nonlinear kip Dynamic Polarization Charge of a Relativistic Test...ASTROPHYSICS ATTN CENTER FOR RADIATION RESEARCH ATTN K. THORNE ATTN C. TEAGUE 130-33 ATTN E. MARX PASADENA, CA 91125 WASHINGTON, DC 20234 UNIVERSITY OF
Slobodan Babic; Cevdet Akyel
2016-01-01
Bitter coils are electromagnets used for the generation of extremely strong magnetic fields superior to 30 T. In this paper we calculate the mutual inductance and the magnetic force between Bitter disk (pancake) coil with the nonlinear radial current and the circular filamentary coil with the azimuthal current. The close form expressed over complete elliptic integrals of the first and second kind as well as Heuman’s Lambda function is obtained for this configuration either for the mutual indu...
Energy Technology Data Exchange (ETDEWEB)
Sridharan, Kumar; Anderson, Mark; Allen, Todd; Corradini, Michael
2012-01-30
on Cr-carbide on the graphite surface. Ni-electroplating dramatically reduced corrosion of alloys, although some diffusion of Fe and Cr were observed occur through the Ni plating. A pyrolytic carbon and SiC (PyC/SiC) CVD coating was also investigated and found to be effective in mitigating corrosion. The KCl-MgCl2 molten salt was less corrosive than FLiNaK fluoride salts for corrosion tests performed at 850oC. Cr dissolution in the molten chloride salt was still observed and consequently Ni-201 and Hastelloy N exhibited the least depth of attack. Grain-boundary engineering (GBE) of Incoloy 800H improved the corrosion resistance (as measured by weight loss and maximum depth of attack) by nearly 50% as compared to the as-received Incoloy 800H sample. Because Cr dissolution is an important mechanism of corrosion, molten salt electrochemistry experiments were initiated. These experiments were performed using anodic stripping voltammetry (ASV). Using this technique, the reduction potential of Cr was determined against a Pt quasi-reference electrode as well as against a Ni(II)-Ni reference electrode in molten FLiNaK at 650 oC. The integrated current increased linearly with Cr-content in the salt, providing for a direct assessment of the Cr concentration in a given salt of unknown Cr concentration. To study heat transfer mechanisms in these molten salts over the forced and mixed convection regimes, a forced convective loop was constructed to measure heat transfer coefficients, friction factors and corrosion rates in different diameter tubes in a vertical up flow configuration in the laminar flow regime. Equipment and instrumentation for the forced convective loop was designed, constructed, and tested. These include a high temperature centrifugal pump, mass flow meter, and differential pressure sensing capabilities to an uncertainty of < 2 Pa. The heat transfer coefficient for the KCl-MgCl2 salt was measured in two different diameter channels (0.083 and 0.370Ã). In the 0
Directory of Open Access Journals (Sweden)
V. O. Kaledin
2014-01-01
Full Text Available In this paper we consider a moving orthotropic cylindrical shell of rotation. The purpose is to assess the choice of kinematic hypothesis for calculating the phase velocities of cylindrical shells. The comparison was done for the two hypotheses, namely: those of Timoshenko and Kirchhoff-Love. The calculation was performed under the following assumptions: all Poisson's ratios of orthotropic material were taken to be zero; the principal axes of anisotropy coincide with the lines of curvature, the coefficients of mutual influence of forces per unit length and bending moments were taken to be zero, which is valid for sufficiently thin shells. Analysis of the phase velocity of the cylindrical shell has shown that at low frequencies of traveling wave Timoshenko’s hypothesis gives an infinite value of the phase velocity. However, with increasing frequency of the traveling wave phase velocities obtained with different kinematic hypotheses, in the limit approach each other. Additionally, this article presents a numerical calculation of the phase velocity of the traveling waves. Calculation technique developed by V.O. Kaledin is based on the assumption that the traveling (direct and reflected waves, forming a standing wave, are in superposition at sustained forced vibrations of a shell. Next, the analytical results, obtained for a cylindrical shell with the harmonic disturbing force acting at the front edge, have been compared with the numerical results obtained under the same assumptions. The difference between the numerical and analytical results is less than 1,5%.We note that many of the well-known works mention low accuracy when using the Kirchhoff-Love hypothesis to calculate phase velocities of the second and higher forms in thin cylindrical shells of rotation. This work is soundly refutes this claim and can form the basis of further studies of wave processes in shells of rotation of arbitrary Gaussian curvature using the Kirchhoff
Energy Technology Data Exchange (ETDEWEB)
Sridharan, Kumar; Anderson, Mark; Allen, Todd; Corradini, Michael
2012-01-30
on Cr-carbide on the graphite surface. Ni-electroplating dramatically reduced corrosion of alloys, although some diffusion of Fe and Cr were observed occur through the Ni plating. A pyrolytic carbon and SiC (PyC/SiC) CVD coating was also investigated and found to be effective in mitigating corrosion. The KCl-MgCl2 molten salt was less corrosive than FLiNaK fluoride salts for corrosion tests performed at 850oC. Cr dissolution in the molten chloride salt was still observed and consequently Ni-201 and Hastelloy N exhibited the least depth of attack. Grain-boundary engineering (GBE) of Incoloy 800H improved the corrosion resistance (as measured by weight loss and maximum depth of attack) by nearly 50% as compared to the as-received Incoloy 800H sample. Because Cr dissolution is an important mechanism of corrosion, molten salt electrochemistry experiments were initiated. These experiments were performed using anodic stripping voltammetry (ASV). Using this technique, the reduction potential of Cr was determined against a Pt quasi-reference electrode as well as against a Ni(II)-Ni reference electrode in molten FLiNaK at 650 oC. The integrated current increased linearly with Cr-content in the salt, providing for a direct assessment of the Cr concentration in a given salt of unknown Cr concentration. To study heat transfer mechanisms in these molten salts over the forced and mixed convection regimes, a forced convective loop was constructed to measure heat transfer coefficients, friction factors and corrosion rates in different diameter tubes in a vertical up flow configuration in the laminar flow regime. Equipment and instrumentation for the forced convective loop was designed, constructed, and tested. These include a high temperature centrifugal pump, mass flow meter, and differential pressure sensing capabilities to an uncertainty of < 2 Pa. The heat transfer coefficient for the KCl-MgCl2 salt was measured in two different diameter channels (0.083 and 0.370Ã). In the 0
Image method in the calculation of the van der Waals force between an atom and a conducting surface
Souza, Reinaldo de Melo e; Sigaud, C; Farina, C
2012-01-01
Initially, we make a detailed historical survey of van der Waals forces, collecting the main references on the subject. Then, we review a method recently proposed by Eberlein and Zietal to compute the dispersion van der Waals interaction between a neutral but polarizable atom and a perfectly conducting surface of arbitrary shape. This method has the advantage of relating the quantum problem to a corresponding classical one in electrostatics so that all one needs is to compute an appropriate Green function. We show how the image method of electrostatics can be conveniently used together with the Eberlein and Zietal mehtod (when the problem admits an image solution). We then illustrate this method in a couple of simple but important cases, including the atom-sphere system. Particularly, in our last example, we present an original result, namely, the van der Waals force between an atom and a boss hat made of a grounded conducting material.
Image method in the calculation of the van der Waals force between an atom and a conducting surface
de Melo e Souza, Reinaldo; Kort-Kamp, W. J. M.; Sigaud, C.; Farina, C.
2013-05-01
After a brief survey of van der Waals forces, we review a method recently proposed by Eberlein and Zietal to compute the dispersion van der Waals interaction between a neutral but polarizable atom and a perfectly conducting surface of arbitrary shape. This method has the advantage of relating the quantum problem to a corresponding classical one in electrostatics in an enlightening way so that all one needs is to compute an appropriate Green function. We show how the image method of electrostatics can be conveniently used together with the Eberlein and Zietal method (when the image solution is known). We then illustrate this method in some simple but important cases, including the atom-sphere system. Finally, we present an original result for the van der Waals force between an atom and a boss hat made of a grounded conducting material.
Design of a laboratory hydraulic device for testing of hydraulic pumps
Directory of Open Access Journals (Sweden)
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.
THE CALCULATION METHOD ABOUT THE FRICTION ARM OF HYDRAULIC STEEL GATE ROLLER%水工钢闸门滚轮的滚动摩擦力臂计算方法
Institute of Scientific and Technical Information of China (English)
高仕赵; 徐国宾
2013-01-01
In order to solve the problem of the calculation method about the rolling friction arm of a hydraulic steel gate roller,the contact problem between wheel and rail is reduced to the contact between the cylinder and the cylinder seat.Taking the contact line as the end of the semicircle,it assumes that the pressure of the contact line is proportional to the height at the point of this semicircle.The analytical solution of a rolling friction arm is derived according to the Boussinesq problem of an infinite half-plane solution.Finally,ANSYS is applied to computing the contact between rolling wheel and rail to verify the correctness of the analytical solution of the rolling friction arm.The results show that the rolling friction arm formula is reasonably simplified,and the calculation accuracy can meet the actual requirements.%为了解决水工钢闸门滚轮在受载荷作用时产生的滚动摩擦力臂的计算方法问题,将滚轮与钢轨的接触问题简化为圆柱与圆柱座之间的接触问题,并以接触线为底作半圆,假设接触线上各点的压力与此半圆在该点的高度成正比.同时根据无限半平面Boussinesq问题的解法推导出滚动摩擦力臂的解析解.最后采用ANSYS建立滚轮全模型与钢轨进行接触分析来验证滚动摩擦力臂解析解的正确性.结果表明该滚动摩擦力臂计算公式简化合理,计算精度能够满足实际要求.
Antunes, A.; Glover, P. M.; Li, Y.; Mian, O. S.; Day, B. L.
2012-07-01
Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.
Antunes, A; Glover, P M; Li, Y; Mian, O S; Day, B L
2012-07-21
Large static magnetic fields may be employed in magnetic resonance imaging (MRI). At high magnetic field strengths (usually from about 3 T and above) it is possible for humans to perceive a number of effects. One such effect is mild vertigo. Recently, Roberts et al (2011 Current Biology 21 1635-40) proposed a Lorentz-force mechanism resulting from the ionic currents occurring naturally in the endolymph of the vestibular system. In the present work a more detailed calculation of the forces and resulting pressures in the vestibular system is carried out using a numerical model. Firstly, realistic 3D finite element conductivity and fluid maps of the utricle and a single semi-circular canal containing the current sources (dark cells) and sinks (hair cells) of the utricle and ampulla were constructed. Secondly, the electrical current densities in the fluid are calculated. Thirdly, the developed Lorentz force is used directly in the Navier-Stokes equation and the trans-cupular pressure is computed. Since the driving force field is relatively large in comparison with the advective acceleration, we demonstrate that it is possible to perform an approximation in the Navier-Stokes equations that reduces the problem to solving a simpler Poisson equation. This simplification allows rapid and easy calculation for many different directions of applied magnetic field. At 7 T a maximum cupula pressure difference of 1.6 mPa was calculated for the combined ampullar (0.7 µA) and utricular (3.31 µA) distributed current sources, assuming a hair-cell resting current of 100 pA per unit. These pressure values are up to an order of magnitude lower than those proposed by Roberts et al using a simplistic model and calculation, and are in good agreement with the estimated pressure values for nystagmus velocities in caloric experiments. This modeling work supports the hypothesis that the Lorentz force mechanism is a significant contributor to the perception of magnetic field induced vertigo.
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
ON INFLUENCE OF KINEMATICS TO EQUIVALENT LINEAR DAMPING OF HELICOPTER BLADE HYDRAULIC DAMPER
Institute of Scientific and Technical Information of China (English)
胡国才; 向锦武; 张晓谷
2002-01-01
An analytical model of hydraulic damper was presented in forward flight accounting for pitch/flap/lag kinematic coupling and its nonlinear force-velocity curve. The fourth order Runge-Kutta was applied to calculate the damper axial velocity in time domain. Fourier series based moving block analysis was applied to calculate equivalent linear damping in terms of transient responses of damper axial velocity. Results indicate that equivalent linear damping will be significantly reduced if pitch/ flap/ lag kinematic coupling introduced for notional model and flight conditions.
Energy Technology Data Exchange (ETDEWEB)
Luo, Ye, E-mail: xw111luoye@gmail.com; Sorella, Sandro, E-mail: sorella@sissa.it [International School for Advanced Studies (SISSA), and CRS Democritos, CNR-INFM, Via Bonomea 265, I-34136 Trieste (Italy); Zen, Andrea, E-mail: zen.andrea.x@gmail.com [Dipartimento di Fisica, Università di Roma “La Sapienza,” Piazzale Aldo Moro 2, I-00185 Rome (Italy)
2014-11-21
We present a systematic study of a recently developed ab initio simulation scheme based on molecular dynamics and quantum Monte Carlo. In this approach, a damped Langevin molecular dynamics is employed by using a statistical evaluation of the forces acting on each atom by means of quantum Monte Carlo. This allows the use of an highly correlated wave function parametrized by several variational parameters and describing quite accurately the Born-Oppenheimer energy surface, as long as these parameters are determined at the minimum energy condition. However, in a statistical method both the minimization method and the evaluation of the atomic forces are affected by the statistical noise. In this work, we study systematically the accuracy and reliability of this scheme by targeting the vibrational frequencies of simple molecules such as the water monomer, hydrogen sulfide, sulfur dioxide, ammonia, and phosphine. We show that all sources of systematic errors can be controlled and reliable frequencies can be obtained with a reasonable computational effort. This work provides convincing evidence that this molecular dynamics scheme can be safely applied also to realistic systems containing several atoms.
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.
Design Calculations and Draft Specifications.
1976-01-01
v ML •. :.? ... *-. .- VJ, The low rpm required precludes the use of a low speed high torque .- - ( LSHT ) hydraulic motor directly without...7. - 33,000 x .75 Max torque required at drive motor : 7.9 x 33,000 = 69.7 ft-lb - L’ 27rx 1.7 x 350 A Sundstrand Model 1MH-02 LSHT hydraulic motor ...large-diameter hydraulic hoses. The procedure followed here is to size hydraulic motors or actuators based on torque, speed, or force requirements
DEFF Research Database (Denmark)
Schløer, Signe; Bredmose, Henrik; Bingham, Harry B.
2016-01-01
and nonlinear irregular wave realizations are calculated using the fully nonlinear potential flow wave model OceanWave3D [1]. The linear and nonlinear wave realizations are compared using both a static analysis on a fixed monopile and dynamic calculations with the aeroelastic code Flex5 [2]. The conclusion from...... this analysis is that linear wave theory is generally sufficient for estimating the fatigue loading, but wave nonlinearity is important in determining the ultimate design loads.......The response of an offshore wind turbine tower and its monopile foundation has been investigated when exposed to linear and fully nonlinear irregular waves on four different water depths. The investigation focuses on the consequences of including full nonlinearity in the wave kinematics. The linear...
Bentley, I; Frauendorf, S
2013-01-01
A model with nucleons in a charge independent potential well interacting by an isovector pairing force is considered. For a 24-dimensional valence space, the Hartree-Bogolyubov (HB) plus Random Phase (RPA) approximation to the lowest eigenvalue of the Hamiltonian is shown to be accurate except near values of the pairing force coupling constant G where the HB solution shifts from a zero to a non-zero pair gap. In the limit G->infinity the HB + RPA is asymptotically exact. The inaccuracy of the HB + RPA in the critical regions of G can be remedied by interpolation. The resulting algoritm is used to calculate pairing corrections in the framework of a Nilsson-Strutinsky calculation of nuclear masses near N = Z for A = 24-100, where N and Z are the numbers of neutrons and protons, and A = N + Z. The dimension of the valence space is 2A in these calculations. Adjusting five liquid drop parameters and a power law expression for the constant G as a function of A allows us to reproduce the measured binding energies of...
Cai, Kaicong; Zheng, Xuan; Du, Fenfen
2017-08-01
The spectroscopy of amide-I vibrations has been widely utilized for the understanding of dynamical structure of polypeptides. For the modeling of amide-I spectra, two frequency maps were built for β-peptide analogue (N-ethylpropionamide, NEPA) in a number of solvents within different schemes (molecular mechanics force field based, GM map; DFT calculation based, GD map), respectively. The electrostatic potentials on the amide unit that originated from solvents and peptide backbone were correlated to the amide-I frequency shift from gas phase to solution phase during map parameterization. GM map is easier to construct with negligible computational cost since the frequency calculations for the samples are purely based on force field, while GD map utilizes sophisticated DFT calculations on the representative solute-solvent clusters and brings insight into the electronic structures of solvated NEPA and its chemical environments. The results show that the maps' predicted amide-I frequencies present solvation environmental sensitivities and exhibit their specific characters with respect to the map protocols, and the obtained vibrational parameters are in satisfactory agreement with experimental amide-I spectra of NEPA in solution phase. Although different theoretical schemes based maps have their advantages and disadvantages, the present maps show their potentials in interpreting the amide-I spectra for β-peptides, respectively.
Directory of Open Access Journals (Sweden)
Slobodan Babic
2016-01-01
Full Text Available Bitter coils are electromagnets used for the generation of extremely strong magnetic fields superior to 30 T. In this paper we calculate the mutual inductance and the magnetic force between Bitter disk (pancake coil with the nonlinear radial current and the circular filamentary coil with the azimuthal current. The close form expressed over complete elliptic integrals of the first and second kind as well as Heuman’s Lambda function is obtained for this configuration either for the mutual inductance or for the magnetic force. The results of this method are compared with those obtained by the improved modified filament method for the presented configuration. All results are in an excellent agreement.
Kongsted, Jacob; Christiansen, Ove
2006-09-28
An automatic and general procedure for the calculation of geometrical derivatives of the energy and general property surfaces for molecular systems is developed and implemented. General expressions for an n-mode representation are derived, where the n-mode representation includes only the couplings between n or less degrees of freedom. The general expressions are specialized to derivative force fields and property surfaces, and a scheme for calculation of the numerical derivatives is implemented. The implementation is interfaced to electronic structure programs and may be used for both ground and excited electronic states. The implementation is done in the context of a vibrational structure program and can be used in combination with vibrational self-consistent field (VSCF), vibrational configuration interaction (VCI), vibrational Moller-Plesset, and vibrational coupled cluster calculations of anharmonic wave functions and calculation of vibrational averaged properties at the VSCF and VCI levels. Sample calculations are presented for fundamental vibrational energies and vibrationally averaged dipole moments and frequency dependent polarizabilities and hyperpolarizabilities of water and formaldehyde.
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
Concept Evaluation for Hydraulic Yaw System
DEFF Research Database (Denmark)
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....
Institute of Scientific and Technical Information of China (English)
王俊伟; 赵利杰; 马芬芝
2014-01-01
In order to improve mining efficiency, reduce the amount of the Roadway Excavation,enhance the mine production safety, based on distributed parameter model, the paper make scientific researches on Long-distance Hydraulic-fiuid Supply. the AMESIM Software is used to establish Long -distance Hydraulic -fiuid supply model, then according to various situations were simulated, finally design Long -distance Hydraulic -fiuid Supply scheme. Through the research, the distance of Long -distance Hydraulic-fiuid Supply scheme for Fully-mechanized Mining Faceis 1500 meters,thatbasically meet the needs of the mining area face of my company.%为了提高回采效率，减小巷道掘进量，增强矿井生产的安全性，基于分布式参数模型，本文对工作面远距离供液技术进行研究。首先使用 AMESIM 软件建立远距离供液模型，然后针对各种情况进行仿真计算，最后设计远距离供液方案。通过研究，远距离供液方案，可以为综采工作面提供1500m 的供液距离，基本满足采区工作面的需要。
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
Energy Technology Data Exchange (ETDEWEB)
Fry, M.A.; Needham, C.E.; Stucker, M.; Chambers, B.S.; Ganong, G.P.
1976-10-01
This laboratory performed Hydrodynamics Unlimited (HULL) calculations of the air blast over a dam for two yields and two pressure regions. A 5th calculation included a rigid blockhouse at the foot of the dam. Although the shielding effect of the dam reduced the incident blast wave overpressure, reflection of the shock from the valley floor raised the peak overpressure up to at least 40% of the free air value. In almost every case, the overpressure impulses near the foot of the dam were greater than or equal to free air values. The rigid blockhouse experienced the most severe overpressure environments. The assumption of a 50-psi hard blockhouse is reasonable. During collapse of the blockhouse, it appears to be rigid to the air flow, since it responds slowly to the rapid air blast. Although there may be other reasons to detonate the weapon on the surface of the reservoir, the best way to destroy the blockhouse and any related structures with air blast, probably would be to detonate the device downstream of the blockhouse.
Calculation Method of Induced Electromotive Force of DC Motor with Wide Brushes%宽电刷直流电机感应电动势算法
Institute of Scientific and Technical Information of China (English)
2013-01-01
电刷宽度对直流电机感应电动势的影响是很大的，因此，在未考虑电刷宽度的条件下所推导出的感应电动势计算式都不够精确，对直流电机尤其是宽电刷直流电机的设计缺乏指导意义。详细分析了电刷宽度对直流电机的感应电动势的影响，给出了宽电刷直流电机感应电动势的计算方法。分析了电刷宽度变化引起感应电动势和电枢电流变化情况，得出了电机在运行中经常出现烧损故障的原因。%The effect of brush width on induced electromotive force of DC motor is obvious. Therefore,the cal-culation of induced electromotive force without considering the brush width is not precise enough,which results in the lack of guiding significance for the design of DC motor,especially DC motor with wide brushes. This pa-per firstly analyzes the effects of the brush width on induced electromotive force of DC motor,and then pro-poses the algorithm for induced electromotive force of DC motor with wide brushes. Through the changes of in-duced electromotive force and armature current caused by the change of the brush width,the reason for burning fault during DC motor running is obtained.
Two-axis hydraulic joint for high speed, heavy lift robotic operations
Energy Technology Data Exchange (ETDEWEB)
Vaughn, M.R.; Robinett, R.D.; Phelan, J.R.; VanZuiden, D.M.
1994-04-01
A hydraulically driven universal joint was developed for a heavy lift, high speed nuclear waste remediation application. Each axis is driven by a simple hydraulic cylinder controlled by a jet pipe servovalve. Servovalve behavior is controlled by a force feedback control system, which damps the hydraulic resonance. A prototype single joint robot was built and tested. A two joint robot is under construction.
Joseph, Lynnette; Sajan, D; Chaitanya, K; Devarajegowda, H C; Isac, Jayakumary
2013-10-01
FT-IR and FT-Raman spectra of 1, 3-Bis (hydroxymethyl) benzimidazolin-2-one were recorded and analyzed in the solid phase. The optimized molecular geometry and vibrational wavenumbers have also been calculated in optimized structure by using DFT method. Scaled quantum mechanical force fields have also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. The red shifting of the O-H stretching wavenumber is due to the formation of O-H···O intermolecular hydrogen bonding. The lowering and splitting of the carbonyl stretching vibrational modes is assigned to the intermolecular association based on C=O···H type hydrogen bonding in the molecule. Chemical interpretation of hyperconjugative interactions was done by natural bond orbital analysis.
Misquitta, Alston J; Szalewicz, Krzysztof
2005-06-01
A symmetry-adapted perturbation theory based on Kohn-Sham determinants [SAPT(KS)] and utilizing asymptotically corrected exchange-correlation potentials has been applied to the He2, Ne2, (H2O)2, and (CO2)2 dimers. It is shown that SAPT(KS) is able to recover the electrostatic, first-order exchange, second-order induction, and exchange-induction energies with an accuracy approaching and occasionally surpassing that of regular SAPT at the currently programmed theory level. The use of the asymptotic corrections is critical to achieve this accuracy. The SAPT(KS) results can be obtained at a small fraction of the time needed for regular SAPT calculations. The robustness of the SAPT(KS) method with respect to the basis set size is also demonstrated. A theoretical justification for high accuracy of SAPT(KS) predictions for the electrostatic, first-order exchange, and second-order induction energies has been provided.
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...
New method to improve dynamic stiffness of electro-hydraulic servo systems
Bai, Yanhong; Quan, Long
2013-09-01
Most current researches working on improving stiffness focus on the application of control theories. But controller in closed-loop hydraulic control system takes effect only after the controlled position is deviated, so the control action is lagged. Thus dynamic performance against force disturbance and dynamic load stiffness can’t be improved evidently by advanced control algorithms. In this paper, the elementary principle of maintaining piston position unchanged under sudden external force load change by charging additional oil is analyzed. On this basis, the conception of raising dynamic stiffness of electro hydraulic position servo system by flow feedforward compensation is put forward. And a scheme using double servo valves to realize flow feedforward compensation is presented, in which another fast response servo valve is added to the regular electro hydraulic servo system and specially utilized to compensate the compressed oil volume caused by load impact in time. The two valves are arranged in parallel to control the cylinder jointly. Furthermore, the model of flow compensation is derived, by which the product of the amplitude and width of the valve’s pulse command signal can be calculated. And determination rules of the amplitude and width of pulse signal are concluded by analysis and simulations. Using the proposed scheme, simulations and experiments at different positions with different force changes are conducted. The simulation and experimental results show that the system dynamic performance against load force impact is largely improved with decreased maximal dynamic position deviation and shortened settling time. That is, system dynamic load stiffness is evidently raised. This paper proposes a new method which can effectively improve the dynamic stiffness of electro-hydraulic servo systems.
Analysis of Innovative Design of Energy Efficient Hydraulic Actuators
Directory of Open Access Journals (Sweden)
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.
Mao, Yuezhi; Demerdash, Omar; Head-Gordon, Martin; Head-Gordon, Teresa
2016-11-08
AMOEBA is a molecular mechanics force field that addresses some of the shortcomings of a fixed partial charge model, by including permanent atomic point multipoles through quadrupoles, as well as many-body polarization through the use of point inducible dipoles. In this work, we investigate how well AMOEBA formulates its non-bonded interactions, and how it implicitly incorporates quantum mechanical effects such as charge penetration (CP) and charge transfer (CT), for water-water and water-ion interactions. We find that AMOEBA's total interaction energies, as a function of distance and over angular scans for the water dimer and for a range of water-monovalent cations, agree well with an advanced density functional theory (DFT) model, whereas the water-halides and water-divalent cations show significant disagreement with the DFT result, especially in the compressed region when the two fragments overlap. We use a second-generation energy decomposition analysis (EDA) scheme based on absolutely localized molecular orbitals (ALMOs) to show that in the best cases AMOEBA relies on cancellation of errors by softening of the van der Waals (vdW) wall to balance permanent electrostatics that are too unfavorable, thereby compensating for the missing CP effect. CT, as another important stabilizing effect not explicitly taken into account in AMOEBA, is also found to be incorporated by the softened vdW interaction. For the water-halides and water-divalent cations, this compensatory approach is not as well executed by AMOEBA over all distances and angles, wherein permanent electrostatics remains too unfavorable and polarization is overdamped in the former while overestimated in the latter. We conclude that the DFT-based EDA approach can help refine a next-generation AMOEBA model that either realizes a better cancellation of errors for problematic cases like those illustrated here, or serves to guide the parametrization of explicit functional forms for short-range contributions from
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
不平衡推力迭代法的改进%Improvement of Iterative Method to Calculate Unbalanced Thrust Force
Institute of Scientific and Technical Information of China (English)
李博; 蔺宗宗; 杨柳
2013-01-01
In the calculation of unbalanced thrust force using iterative algorithm, the inter-slice force direction is assumed to be parallel to the sliding surface of the upper slice bottom, which results in excessive calculation value and leads to unsafty of projects. The authors improved the method through correcting the angle between the directions of inter-slice forces in the slope. What' s more, we derived the formulas respectively in the presence of and in the absence of seismic force. On the basis of Visual Basic programming, we applied the improved formula to the calculation of an example and compared the result with that of the previous unimproved formula. The result indicates that the improved method is practicable, and presents a more reasonable physical process.%不平衡推力迭代法假定条块作用力方向平行于上一条块底滑面,这样可能导致计算结果偏大,使工程偏于不安全,通过对坡体滑块间作用力方向角度的修正,对不平衡推力迭代法做了改进,并在不考虑地震力和考虑地震力的情况下分别进行了公式的推导.针对具体算例,利用改进后的计算公式,在Visual Basic编程的基础上,对具体算例进行了计算,并和改进前的方法做了比较.结果表明:改进后的方法对改进前的方法具有一定程度的修正作用,且改进方法的物理过程更加合理,在具体应用上具有一定的实用性.
Hopper, Seth; Kavanagh, Chris; Ottewill, Adrian C.
2016-02-01
We present a method for solving the first-order Einstein field equations in a post-Newtonian (PN) expansion. Our calculations generalize the work of Bini and Damour and subsequently Kavanagh et al. to consider eccentric orbits on a Schwarzschild background. We derive expressions for the retarded metric perturbation at the location of the particle for all ℓ-modes. We find that, despite first appearances, the Regge-Wheeler gauge metric perturbation is C0 at the particle for all ℓ. As a first use of our solutions, we compute the gauge-invariant quantity ⟨U ⟩ through 4PN while simultaneously expanding in eccentricity through e10. By anticipating the e →1 singular behavior at each PN order, we greatly improve the accuracy of our results for large e . We use ⟨U ⟩ to find 4PN contributions to the effective one body potential Q ^ through e10 and at linear order in the mass ratio.
Bullimore, Sharon R; Saunders, Travis J; Herzog, Walter; MacIntosh, Brian R
2010-10-01
The maximal shortening velocity of a muscle (V(max)) provides a link between its macroscopic properties and the underlying biochemical reactions and is altered in some diseases. Two methods that are widely used for determining V(max) are afterloaded and isotonic release contractions. To determine whether these two methods give equivalent results, we calculated V(max) in 9 intact single fibres from the lumbrical muscles of the frog Xenopus laevis (9.5-15.5 °C, stimulation frequency 35-70 Hz). The data were modelled using a 3-state cross-bridge model in which the states were inactive, detached, and attached. Afterloaded contractions gave lower predictions of Vmax than did isotonic release contractions in all 9 fibres (3.20 ± 0.84 versus 4.11 ± 1.08 lengths per second, respectively; means ± SD, p = 0.001) and underestimated unloaded shortening velocity measured with the slack test by an average of 29% (p = 0.001, n = 6). Excellent model predictions could be obtained by assuming that activation is inhibited by shortening. We conclude that under the experimental conditions used in this study, afterloaded and isotonic release contractions do not give equivalent results. When a change in the V(max) measured with afterloaded contractions is observed in diseased muscle, it is important to consider that this may reflect differences in either activation kinetics or cross-bridge cycling rates.
Hopper, Seth; Ottewill, Adrian C
2015-01-01
We present a method for solving the first-order field equations in a post-Newtonian (PN) expansion. Our calculations generalize work of Bini and Damour~\\cite{BiniDamo13} and subsequently Kavanagh et al.~\\cite{KavaOtteWard15}, to consider eccentric orbits on a Schwarzschild background. We derive expressions for the retarded metric perturbation at the location of the particle for all $\\ell$-modes. We find that, despite first appearances, the Regge-Wheeler gauge metric perturbation is $C^0$ at the particle for all $\\ell$. As a first use of our solutions, we compute the gauge-invariant quantity $\\langle U \\rangle$ through 4PN while simultaneously expanding in eccentricity through $e^{10}$. By anticipating the $e\\to 1$ singular behavior at each PN order, we greatly improve the accuracy of our results for large $e$. We use $\\langle U \\rangle$ to find 4PN contributions to the effective one body potential $q(u)$ through $e^{10}$ and at linear order in the mass-ratio.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Feng; Tominaga, Keisuke, E-mail: atmyh@ntu.edu.tw, E-mail: tominaga@kobe-u.ca.jp, E-mail: junichi.nishizawa@hanken.jp [Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-0013 (Japan); Hayashi, Michitoshi, E-mail: atmyh@ntu.edu.tw, E-mail: tominaga@kobe-u.ca.jp, E-mail: junichi.nishizawa@hanken.jp; Wang, Houng-Wei [Center for Condensed Matter Sciences, National Taiwan University, 1 Roosevelt Rd., Sec. 4, Taipei 10617, Taiwan (China); Kambara, Ohki; Sasaki, Tetsuo [Research Institute of Electronics, Shizuoka University, 3-5-1 Jyohoku, Naka-ku, Hamamatsu, Shizuoka 432-8561 (Japan); Nishizawa, Jun-ichi, E-mail: atmyh@ntu.edu.tw, E-mail: tominaga@kobe-u.ca.jp, E-mail: junichi.nishizawa@hanken.jp [Jun-ichi Nishizawa Memorial Research Center, Tohoku University, 519-1176 Aoba, Aramaki, Aoba-ku, Sendai 980-0845 (Japan)
2014-05-07
The phonon modes of molecular crystals in the terahertz frequency region often feature delicately coupled inter- and intra-molecular vibrations. Recent advances in density functional theory such as DFT-D{sup *} have enabled accurate frequency calculation. However, the nature of normal modes has not been quantitatively discussed against experimental criteria such as isotope shift (IS) and correlation field splitting (CFS). Here, we report an analytical mode-decoupling method that allows for the decomposition of a normal mode of interest into intermolecular translation, libration, and intramolecular vibrational motions. We show an application of this method using the crystalline anthracene system as an example. The relationship between the experimentally obtained IS and the IS obtained by PBE-D{sup *} simulation indicates that two distinctive regions exist. Region I is associated with a pure intermolecular translation, whereas region II features coupled intramolecular vibrations that are further coupled by a weak intermolecular translation. We find that the PBE-D{sup *} data show excellent agreement with the experimental data in terms of IS and CFS in region II; however, PBE-D{sup *} produces significant deviations in IS in region I where strong coupling between inter- and intra-molecular vibrations contributes to normal modes. The result of this analysis is expected to facilitate future improvement of DFT-D{sup *}.
OPTIMUM DESIGN AND NON-LINEAR MODEL OF POWERPLANT HYDRAULIC MOUNT SYSTEM
Institute of Scientific and Technical Information of China (English)
Shi Wenku; Min Haitao; Dang Zhaolong
2003-01-01
6-DOF non-linear mechanics model of powerplant hydraulic mount system is established. Optimum design of the powerplant hydraulic mount system is made with the hydraulic mount parameters as variables and with uncoupling of energy, rational disposition of nature frequency and minimum of reactive force at mount's location as objective functions. And based on the optimum design, software named ODPHMS (optimum design of powerplant hydraulic mount system) used in powerplant mount system optimum design is developed.
三维滑坡推力计算方法探讨%CALCULATION METOD FOR DRIVING FORCE OF THREE-DIMENSIONAL LANDSLIDES
Institute of Scientific and Technical Information of China (English)
张常亮; 李同录; 李萍
2011-01-01
The common two-dimensional(2D)methods for the driving forces of landslides don't consider the lateral variation and confinements,which can make the stabilization design un-precisely. Three-dimensional(3D) method can reflect the spatialdistribution of the driving force of landslide. So it can resolve the problem of 2D methods. This paper provides a general formula for calculating the driving force of 3D landslide. It is based on the method of the general form of 3D equilibrium proposed by the authors. The paper presents case studies and a comparison between the 2D and 3D methods. Then,it obtains a distribution function of the lateral variation. This function reflects the spatial distribution of the driving force of 3D landslides,and makes slope stabilization design more reasonable.%常规二维滑坡推力计算没有考虑其横向变化,导致设计过于保守,三维推力计算方法的提出则能体现滑坡推力的空间分布,解决二维存在的问题.本文在三维极限平衡法统一模型的基础上,建立了求解三维滑坡推力的统一公式.利用实例,通过二维推力计算与三维计算结果的对比分析,获得三维推力的横向分布函数,有效反映出三维滑坡推力的空间分布状态,所得三维滑坡推力应用于设计更合理.
Institute of Scientific and Technical Information of China (English)
廖宗蓉
2016-01-01
Hydraulic transient (water hammer)refers to the dynamic change of flow and pres-sure in hydraulic system,which comes from the fact that transient increase of water pressure in the pipes would cause pressure waves and transmit it in sound velocity.In this paper,hydraulic transi-ent was analyzed through rigid water hammer model and flexible water hammer model.Simplified finite difference equation was adopted to build a characteristics-method mathematical model for hy-draulic transient and set up boundary conditions for pump motions and valve motions.Characteris-tic method equation and boundary conditions equation were used to get the transient of water hammer waves in pipelines so as to solve the problems of water hammer in complicated pipeline sys-tem and boundary conditions.%由于管道内压力瞬间升高，压力波在管道内以声速传递，导致水力系统流量和压力动态变化，即产生水力瞬变(水锤)，通过刚性水锤模型和弹性水锤模型分析给水管线水力瞬变，采用简化的有限差分方程，建立特征线法水力瞬变数学模型，并建立了泵、阀动作的边界条件，可借助于特征线方程和边界条件方程，求解管线内水锤波的暂态，以解决复杂的管路系统和边界条件的水锤问题。
Calculation of Press Fitting Force for Involute Spline Fit%渐开线花键配合压装力计算
Institute of Scientific and Technical Information of China (English)
王宋军; 陈启云; 李慧军; 由毅; 冯擎峰
2013-01-01
The involute spline coupling is widely applied in automobile industry due to strong transmission torque and high centering accuracy.To assure the concentricity of internal and external splines, the coupling method of major diameter center-ing spline interference fit is mostly adopted between gears and shafts in a vehicle transmission.However, there are no fit cate-gories and calculating method of press fitting force in China′s involute spline fit standard.In this paper, the press fitting force of major diameter centering involute spline is calculated using the press coupling calculation method on a smooth cylindrical surface, thus the basis for establishing the press fitting process of involute spline is provided.% 渐开线花键联结因其传递扭矩大、定心精度高等优点，在汽车行业得到广泛应用。为保证内、外花键同轴度，在汽车变速器中齿轮与轴多采用大径定心的花键过盈配合联结方式。在我国渐开线花键配合标准中没有此配合类别及其压装力计算方法。笔者试以光滑圆柱面过盈联结计算方法计算大径定心的渐开线花键配合压装力，为制定渐开线花键压装工艺提供依据。
Digging Soil Experiments for Micro Hydraulic Excavators based on Model Predictive Tracking Control
Tomatsu, Takumi; Nonaka, Kenichiro; Sekiguchi, Kazuma; Suzuki, Katsumasa
2016-09-01
Recently, the increase of burden to operators and lack of skilled operators are the issue in the work of the hydraulic excavator. These problems are expected to be improved by autonomous control. In this paper, we present experimental results of hydraulic excavators using model predictive control (MPC) which incorporates servo mechanism. MPC optimizes digging operations by the optimal control input which is calculated by predicting the future states and satisfying the constraints. However, it is difficult for MPC to cope with the reaction force from soil when a hydraulic excavator performs excavation. Servo mechanism suppresses the influence of the constant disturbance using the error integration. However, the bucket tip deviates from a specified shape by the sudden change of the disturbance. We can expect that the tracking performance is improved by combining MPC and servo mechanism. Path-tracking controls of the bucket tip are performed using the optimal control input. We apply the proposed method to the Komatsu- made micro hydraulic excavator PC01 by experiments. We show the effectiveness of the proposed method through the experiment of digging soil by comparing servo mechanism and pure MPC with the proposed method.
Directory of Open Access Journals (Sweden)
Bartlomiej Zylinski
2011-01-01
Full Text Available Finite element method analysis of main lines of hydraulic central loading system installation expansion loops mounted on product and chemical tankers has been presented in the paper. The axial forces problem in installations mounted along the ship's open decks executed from hull deformations on waves and thermal stresses is given. Use of "U" type expansion loops is described. Results of forces in anchor points and stresses of Mises due to expansion loop deformations are shown. Calculations were made by ABAQUS Ver.6.7 FEM computer program.
Modeling and parameter estimation for hydraulic system of excavator's arm
Institute of Scientific and Technical Information of China (English)
HE Qing-hua; HAO Peng; ZHANG Da-qing
2008-01-01
A retrofitted electro-bydraulic proportional system for hydraulic excavator was introduced firstly. According to the principle and characteristic of load independent flow distribution(LUDV)system, taking boom hydraulic system as an example and ignoring the leakage of hydraulic cylinder and the mass of oil in it,a force equilibrium equation and a continuous equation of hydraulic cylinder were set up.Based On the flow equation of electro-hydraulic proportional valve, the pressure passing through the valve and the difference of pressure were tested and analyzed.The results show that the difference of pressure does not change with load, and it approximates to 2.0 MPa. And then, assume the flow across the valve is directly proportional to spool displacement andis not influenced by load, a simplified model of electro-hydraulic system was put forward. At the same time, by analyzing the structure and load-bearing of boom instrument, and combining moment equivalent equation of manipulator with rotating law, the estimation methods and equations for such parameters as equivalent mass and bearing force of hydraulic cylinder were set up. Finally, the step response of flow of boom cylinder was tested when the electro-hydraulic proportional valve was controlled by the stepcurrent. Based on the experiment curve, the flow gain coefficient of valve is identified as 2.825×10-4m3/(s·A)and the model is verified.
滁河特大桥吊杆张拉控制力计算%Calculation of Control Forces for Tensioning of Suspenders of Chuhe River Bridge
Institute of Scientific and Technical Information of China (English)
陈强; 黎曙文; 瞿国召; 许三平; 李学斌
2011-01-01
To realize the tensioning of suspenders of tied arch bridge in one step and to avoid the late time adjusting of cable forces of the suspenders, in the light of the structural characteristics of Chuhe River Bridge (a Nilsen structure system) and with the aim that the cable forces of the suspenders of the completed bridge could meet the design requirements, the optimal math-ematic model and the iteration algorithm process were put forward, the control forces for the tensioning of the suspenders were optimally calculated, the control forces that comprehensively con-sidered the design requirements of the completed bridge were given and the control of the construction process of the bridge was finally successfully implemented. Practice proves that the utilization of the optimized control forces for the tensioning of the suspenders can meet the requirements for the strength safety and stability of the arch ribs and tie beams in the construction and the multi-time tensioning and adjusting of the suspenders is therefore avoided.%为了实现系杆拱桥吊索(或吊杆)力张拉的“一步到位”,避免后期的索力调整,针对滁河特大桥(尼尔森结构体系)的结构特点,以成桥状态下的吊杆力满足设计要求为目标,提出了优化数学模型及迭代算法实现过程,对吊杆张拉控制力进行了优化计算,给出了综合考虑成桥状态满足设计要求的吊杆张拉控制力,成功地进行了滁河特大桥施工过程控制.实践证明,采用优化的吊杆张拉控制力,能够满足该桥施工过程中拱肋、系梁的强度安全和稳定性要求,避免了吊杆多次张拉及调整方案.
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...
DEFF Research Database (Denmark)
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...
Energy Technology Data Exchange (ETDEWEB)
Sato, N. [Tohoku University, Sendai (Japan); Hayashi, S.; Hayase, T.; Shirai, A. [Tohoku Univ., Sendai (Japan). Inst. of Fluid Science
2000-01-15
In this study, the effect of a flange on the compensation of flow force in the main poppet valve of the hydraulic semi-active damper has been studied via numerical simulation. First, validity of the numerical analysis was confirmed by comparison between the computational and experimental results. Then, the mathematical models for the flow force acting on the poppet valves both with or without flange for converged flow were obtained based on the computational results. Introducing these mathematical models to the equivalent model of the whole semi-active damper system in the previous paper, the effects of the flow force on the stability of the damper system were investigated. As the result, the flange improves the stability of the system when the pressure difference and the main valve displacement are relatively large. (author)
Digital hydraulic valving system. [design and development
1973-01-01
The design and development are reported of a digital hydraulic valving system that would accept direct digital inputs. Topics include: summary of contractual accomplishments, design and function description, valve parameters and calculations, conclusions, and recommendations. The electrical control circuit operating procedure is outlined in an appendix.
Reducing-resistance mechanism of vibratory excavation of hydraulic excavator
Institute of Scientific and Technical Information of China (English)
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.
Design of a hydraulic actuator for active control of rotating machinery
Rashidi, Majid; Dirusso, Eliseo
1991-01-01
A hydraulic actuator is described which consists of a pump, a hydraulic servo-valve, and a thin elastic plate which transduces the generated pressure variations into forces acting on a mass which simulates the bearing of a rotor system. An actuator characteristic number is defined to provide a base for an optimum design of force actuators with combined weight, frequency, and force considerations. This characteristic number may also be used to compare hydraulic and electromagnetic force actuators. In tests, this actuator generated 182.3 Newton force at a frequency of 100 Hz and a displacement amplitude of 5.8 x 10 exp -5 meter.
Bachu, Stefan; Michael, Karsten
2002-03-01
Although not fully adequate, freshwater hydraulic heads have been used historically to represent and analyze variable-density flow in sloping aquifers in sedimentary basins. The use of environmental heads is valid only for strictly vertical flow in unconfined aquifers, while using variable-density hydraulic heads contravenes Darcy's law. Although the use of hydraulic-head surfaces is the simplest and quickest means of flow analysis and interpretation, preceding other methods such as numerical modeling, it introduces some errors that should be assessed and minimized in order to provide the most accurate flow representation. A first error is introduced when approximating the potential and buoyancy components along aquifer slope of the flow-driving force with their projections onto the horizontal plane. This error is most probably negligibly small for sloping aquifers in undisturbed sedimentary basins, but may be significant for aquifers dipping at a significant angle, such as in folded strata. A second error is introduced when using only hydraulic heads in the representation and analysis, and neglecting the buoyancy component of the flow-driving force. The significance of this error can be assessed by performing a Driving Force Ratio (DFR) analysis. There is no single or critical value of the DFR, below which the error in using hydraulic heads alone is negligible, and above which it is not acceptable anymore; rather, the decision regarding the error acceptability should and can be made on a case by case basis. The DFR, hence the errors in flow direction and magnitude, can be minimized for any given aquifer by using an optimum reference density in hydraulic-head calculations that is the areally-weighted average density of formation water in that aquifer. In flow analyses based on potentiometric surfaces, the use of freshwater as the reference density actually maximizes the errors introduced by the neglect of the buoyancy component of the flow-driving force because it
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.
Thermal-hydraulic design and transient evaluation of a small long-life HTR
Energy Technology Data Exchange (ETDEWEB)
Ding, Ming [Harbin Engineering University, Nantong Street 145, 150001 Harbin (China); Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Kloosterman, Jan Leen, E-mail: j.l.kloosterman@tudelft.nl [Delft University of Technology, Mekelweg 15, 2629 JB Delft (Netherlands)
2013-02-15
Highlights: ► We present the thermal-hydraulic evaluations of a small, long-life and block-type HTR using the DALTON/THERMIX code system. ► A cross section generation methodology is developed and verified for the diffusion calculations of the small HTR. ► The thermal-hydraulic characteristics of the small HTR during pressurized loss of forced-cooling incidents are compared with depressurized loss of forced-cooling ones. ► The thermal-hydraulic characteristics of a cylindrical core are compared with an annular one. ► Thermal power limit of the small HTR is investigated based on depressurized loss of forced-cooling incidents. -- Abstract: Small long-life high temperature gas-cooled reactors (HTRs) may provide electricity or heat for remote areas or industrial users in developed and/or developing countries. Moreover, small HTRs have advantages over large nuclear reactors of demonstrated inherent safety, transportability, modular construction, and flexible site selection. This paper presents the thermal-hydraulic evaluations of the U-Battery, which is a small, long-life and block-type HTR using the DALTON/THERMIX code system. The thermal-hydraulic characteristics of a cylindrical design and an annular design of the U-Battery were evaluated for loss of forced-cooling (LOFC) incidents including depressurized LOFC (DLOFC) and pressurized LOFC (PLOFC) incidents. The calculations show that the stronger natural circulation during the PLOFC makes the reactor core cool faster than during the DLOFC, flattens the radial solid temperature distribution, and transfers more heat from the hot regions (bottom and center of the reactor core) to cold regions (top and periphery of the reactor core). Although the natural circulation in the reactor core is so weak that it is neglected during the DLOFC, the decay heat is removed passively by conduction without any violation of the temperature limits for the 20 MWth U-Battery. The comparisons of the cylindrical and annular reactor
OPTIMAL HYDRAULIC DESIGN AND CAD APPLICATIONS OF AXIAL FLOW HYDRAULIC TURBINE'S RUNNER
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A method of the optimal hydraulic design and CAD application of runner blades of axial-flow hydraulic turbines are discussed on the basis of optimization principle and CAD technique in this paper. Based on the theory of fluid dynamics, the blade′s main geometrical parameter, working parameters and performances index of the blades and the relationship between them are analysed, and the mathematical model of optimal hydraulic design of axial-flow runners has been established. Through nonlinear programming, the problems can be solved. By making use of the calculation geometry and computer graphics, the distribution method of the singular points, and an CAD applied software, an optimal hydraulic design are presented.
Mechanisms and Kinematics of Hydraulic Support for Top-Coal Caving
Institute of Scientific and Technical Information of China (English)
董志峰; 王寿峰; 常宏; 吴建
2001-01-01
The structure and characteristic of new type of hydraulic support for top-coal caving were discussed. The mechanism and kinematics of the hydraulic support were analyzed. The formulas were deduced to calculate the velocity and acceleration of top beam, shield beam, front and back legs, which give the solution to the design and research for hydraulic support.
Error Analysis and Compensation Method on the Mechanical Structure of the Hydraulic Control System
Directory of Open Access Journals (Sweden)
Luo Yanyan
2016-01-01
Full Text Available Mechanical deformation of mechanical transmission part in hydraulic control system directly affects the loading accuracy of the system. For improving the mechanical properties of the system, The force analysis and motion analysis of mechanism are simulated based on the four-bar linkage structure (FLS, and kinematics simulation is designed by using Matlab program, then came to a system error bar graph. The system error was calculated accurately according to the results of the structural mechanics simulation made by Solidworks motion module. The structure of the system will be modified when systematic errors exceed the required limit values until it reach the required value.
Hydraulic conductance and viscous coupling of three-phase layers in angular capillaries
Dehghanpour, H.; Aminzadeh, B.; Dicarlo, D. A.
2011-06-01
Predicting three-phase relative permeability by network models requires reliable models for hydraulic conductance of films and layers stabilized by capillary forces at the pore level. We solve the creeping flow approximation of the Navier-Stokes equation for stable wetting and intermediate layers in the corner of angular capillaries by using a continuity boundary condition at the layer interface. We find significant coupling between the condensed phases and calculate the generalized mobilities by solving cocurrent and countercurrent flow of wetting and intermediate layers. Finally, we present a simple heuristic model for the generalized mobilities as a function of the geometry and viscosity ratio.
Energy Technology Data Exchange (ETDEWEB)
Wang, Xiaohong; Bowman, Joel M., E-mail: jmbowma@emory.edu [Cherry L. Emerson Center for Scientific Computation and Department of Chemistry, Emory University, Atlanta, Georgia 30322 (United States); Huang, Xinchuan [SETI Institute, 189 Bernardo Ave, Suite 100, Mountain View, California 94043 (United States); Lee, Timothy J., E-mail: Timothy.J.Lee@nasa.gov [MS 245-1, NASA Ames Research Center, Mofffett Field, California 94035 (United States)
2013-12-14
We report a CCSD(T)/cc-pCV5Z quartic force field (QFF) and a semi-global CCSD(T)-F12b/aug-cc-pVTZ potential energy surface (PES) for singlet, cyclic C{sub 4}. Vibrational fundamentals, combinations, and overtones are obtained using vibrational second-order perturbation theory (VPT2) and the vibrational configuration-interaction (VCI) approach. Agreement is within 10 cm{sup −1} between the VCI calculated fundamentals on the QFF and PES using the MULTIMODE (MM) program, and VPT2 and VCI results agree for the fundamentals. The agreement between VPT2-QFF and MM-QFF results is also good for the C{sub 4} combinations and overtones. The J = 1 and J = 2 rovibrational energies are reported from both VCI (MM) on the PES and VPT2 on the QFF calculations. The spectroscopic constants of {sup 12}C{sub 4} and two C{sub 2v}-symmetry, single {sup 13}C-substituted isotopologues are presented, which may help identification of cyclic C{sub 4} in future experimental analyses or astronomical observations.
Martini, M; Hilaire, S; Goriely, S; Lechaftois, F
2016-01-01
Valuable theoretical predictions of nuclear dipole excitations in the whole chart are of great interest for different nuclear applications, including in particular nuclear astrophysics. Here we present large-scale calculations of the $E1$ $\\gamma$-ray strength function obtained in the framework of the axially-symmetric deformed QRPA based on the finite-range Gogny force. This approach is applied to even-even nuclei, the strength function for odd nuclei being derived by interpolation. The convergence with respect to the adopted number of harmonic oscillator shells and the cut-off energy introduced in the 2-quasiparticle (2-$qp$) excitation space is analyzed. The calculations performed with two different Gogny interactions, namely D1S and D1M, are compared. A systematic energy shift of the $E1$ strength is found for D1M relative to D1S, leading to a lower energy centroid and a smaller energy-weighted sum rule for D1M. When comparing with experimental photoabsorption data, the Gogny-QRPA predictions are found to...
Institute of Scientific and Technical Information of China (English)
陈卫; 贾鸿益
2014-01-01
This paper is targeted at the problem of slag field drainage discharge in the original design scheme on Huangdeng Hydro‐power Station .It meets the needs of safe operation ,optimizes the discharge chute type design from the angle of hydraulics .Accord‐ing to the running status in the discharge and for the sake of improving flow regime and the safe operation of side slopes at drainage holes as well as the discharge chutes ,hydraulic characteristics are analyzed and structural shape modification is conducted for dis‐charge chute .%针对澜沧江黄登水电站弃渣场高边坡排水泄槽原设计方案存在的问题，从水力学角度对泄槽体型进行优化设计，使其满足安全运行的需要。根据泄槽运行现状，为改善水流流态，保证排水洞出口边坡和泄槽运行安全，对泄槽段水力学特性进行分析和结构体型进行改造设计。
Model based monitoring of wellbore hydraulics for abnormal event detection
Energy Technology Data Exchange (ETDEWEB)
Todorov, Dimitar; Fruhwirth, Rudolf K. [Thonhauser Data Engineering GmbH, Leoben (Austria); Thonhauser, Gerhard [Montanuniversitaet Leoben (Austria)
2013-03-15
With the increasing demand for energy in the last decades, the petroleum industry was forced to push the limits to levels that have never been reached before. Exploring very deep waters, drilling under varying conditions of extreme pressure and temperature and dealing with issues, which involve a new level of understanding, are challenges, which need to be overcome in order to safely and successfully accomplish the planned goals. Operating under such circumstances obligates the driller to be extremely precise in his actions. Even with the driller's extensive experience and training, the possible reaction time is in some cases extremely short. This article discusses the reasons for automatic trouble event recognition systems in the drilling process and how these affect the drilling operations and optimization processes. In this respect a concept of a real time hydraulic monitor will be developed helping the driller to visualize calculations in a plot, showing the pump limitations, the limitations due to the formation fracture gradient and the hole cleaning requirements. Additionally, taking into account the complete wellbore hydraulics and introducing various well behavior models and different algorithms, the system is capable of operating as a real-time indicator for undesired downhole events. (orig.)
Issues Related To Troubleshooting Of Avionic Hydraulic Units
Directory of Open Access Journals (Sweden)
Jastrzębski Grzegorz
2014-12-01
Full Text Available The paper outlines workflows associated with troubleshooting of avionic hydraulic systems with detailed description of the troubleshooting algorithm and classification of diagnostic signals provided by avionic hydraulic systems and their subassemblies. Attention is paid to measurement sequences for diagnostic signals from hydraulic systems, circuits and units. Detailed description is dedicated to an innovative design of a troubleshooting device intended for direct measurements of internal leaks from avionic hydraulic units. Advantages of the proposed measurement method are summarized with benefits from use of the presented device and compared against the methods that are currently in use. Subsequent phases of the troubleshooting process are described with examples of measurement results that have been acquired from subassemblies of hydraulic systems of SU-22 aircrafts currently in service at Polish Air Forces with consideration given to cases when the permissible threshold of diagnostic signals were exceeded. Finally, all results from investigations are subjected to thorough analysis.
Energy Technology Data Exchange (ETDEWEB)
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.
ITHNA.SYS: An Integrated Thermal Hydraulic and Neutronic Analyzer SYStem for NUR research reactor
Energy Technology Data Exchange (ETDEWEB)
Mazidi, S., E-mail: samirmazidi@gmail.com [Division Physique et Applications Nucléaires, Centre de Recherche Nucléaire de Draria (CRND), BP 43 Sebala, Draria, Alger (Algeria); Meftah, B., E-mail: b_meftah@yahoo.com [Division Physique et Applications Nucléaires, Centre de Recherche Nucléaire de Draria (CRND), BP 43 Sebala, Draria, Alger (Algeria); Belgaid, M., E-mail: belgaidm@yahoo.com [Faculté de Physique, Université Houari Boumediene, USTHB, BP 31, Bab Ezzouar, Alger (Algeria); Letaim, F., E-mail: fletaim@yahoo.fr [Faculté des Sciences et Technologies, Université d’El-oued, PO Box 789, El-oued (Algeria); Halilou, A., E-mail: hal_rane@yahoo.fr [Division Réacteur NUR, Centre de Recherche Nucléaire de Draria, BP 43 Sebala, Draria, Alger (Algeria)
2015-08-15
Highlights: • We develop a neutronic and thermal hydraulic MTR reactor analyzer. • The analyzer allows a rapid determination of the reactor core parameters. • Some NUR reactor parameters have been analyzed. - Abstract: This paper introduces the Integrated Thermal Hydraulic and Neutronic Analyzer SYStem (ITHNA.SYS) that has been developed for the Algerian research reactor NUR. It is used both as an operating aid tool and as a core physics engineering analysis tool. The system embeds three modules of the MTR-PC software package developed by INVAP SE: the cell calculation code WIMSD, the core calculation code CITVAP and the program TERMIC for thermal hydraulic analysis of a material testing reactor (MTR) core in forced convection. ITHNA.SYS operates both in on-line and off-line modes. In the on-line mode, the system is linked, via the computer parallel port, to the data acquisition console of the reactor control room and allows a real time monitoring of major physical and safety parameters of the NUR core. PC-based ITHNA.SYS provides a viable and convenient way of using an accumulated and often complex reactor physics stock of knowledge and frees the user from the intricacy of adequate reactor core modeling. This guaranties an accurate, though rapid, determination of a variety of neutronic and thermal hydraulic parameters of importance for the operation and safety analysis of the NUR research reactor. Instead of the several hours usually required, the processing time for the determination of such parameters is now reduced to few seconds. Validation of the system was performed with respect to experimental measurements and to calculations using reference codes. ITHNA.SYS can be easily adapted to accommodate other kinds of MTR reactors.
Institute of Scientific and Technical Information of China (English)
吴松柏; 余明辉
2014-01-01
The paper presents a study on non-cohesive and cohesive homogenous bank failure processes,in⁃fluence of bank failure mass on bank re-collapse as well as the interaction between bank failure and bed evolution through a series of experiments carried out in a 180° bend rectangular flume. The results reveal the iteration cycle between bank erosion and bed deformation;basal erosion due to fluvial hydraulic force, bank failure under the influence of gravity, failure block staying at bank toe temporarily or being remobi⁃lized by the flow,exchange between bank failure mass and bed material,bed-material load being reworked or transported either as bed load or as suspended load, and bed deformation. Same as bank failure, the mixing of bank failure mass and bed material is more serious near the curved flow apex. Moreover,non-co⁃hesive bank failure tends to occur near the water surface, while cohesive bank failure near the bank toe. For non-cohesive material, the bank erosion amount and residual amount of bank failure mass on the bed increase with the near-bank velocity or bed movability. But for cohesive material, only bank erosion amount obeys the above rule. In addition, the research indicates that the mechanism and patterns of bank collapse and interaction between bank failure and bed evolution, which could provide a theoretical basis for further study.%河岸崩塌是河道横向变形的重要表现形式，崩塌体作为陡增的泥沙源反作用于河床演变，进一步影响岸坡的二次崩塌。在弯道水槽中展开系列试验，研究水力作用下非黏性及黏性均质岸坡冲刷崩塌力学机理、塌岸淤床交互作用过程及其影响因素。试验表明，水流冲刷过程中岸坡破坏是水流淘刷岸坡坡脚、岸坡崩塌及崩塌体淤积坡脚，并在河床上分解、输移掺混中交互作用的反复循环过程。岸坡崩塌、崩塌体与河床发生掺混最剧烈处位于弯道出口水流顶冲点附近，非黏
Hydraulics and pneumatics a technician's and engineer's guide
Parr, Andrew
2011-01-01
Nearly all industrial processes require objects to be moved, manipulated or subjected to some sort of force. Such movements and manipulations are frequently accomplished by means of devices driven by liquids (hydraulics) or air (pneumatics), the subject of this book. Hydraulics and Pneumatics is written by a practicing process control engineer as a guide to the successful operation of hydraulic and pneumatic systems for all engineers and technicians working with them. Keeping mathematics and theory to a minimum, this practical guide is thorough but accessible to technicians without a
Representing plant hydraulics in a global Earth system model.
Kennedy, D.; Gentine, P.
2015-12-01
Earth system models need improvement to reproduce observed seasonal and diurnal cycles of photosynthesis and respiration. Model water stress parameterizations lag behind the plant physiology literature. A plant hydraulics model is developed and deployed in a global Earth system model (NCAR CESM 1.2.2 with CLM 4.5). Assimilation and transpiration are attenuated according to literature cavitation curves. Water stress is evaluated based on plant functional type hydraulic parameters forced by soil moisture and atmospheric conditions. Resolving the plant water status allows for modelling divergent strategies for water stress. The case of isohydric versus anisohydric species is presented, showing that including plant hydraulic traits alter modelled photosynthesis and transpiration.
Integrated hydraulic cooler and return rail in camless cylinder head
Energy Technology Data Exchange (ETDEWEB)
Marriott, Craig D [Clawson, MI; Neal, Timothy L [Ortonville, MI; Swain, Jeff L [Flushing, MI; Raimao, Miguel A [Colorado Springs, CO
2011-12-13
An engine assembly may include a cylinder head defining an engine coolant reservoir, a pressurized fluid supply, a valve actuation assembly, and a hydraulic fluid reservoir. The valve actuation assembly may be in fluid communication with the pressurized fluid supply and may include a valve member displaceable by a force applied by the pressurized fluid supply. The hydraulic fluid reservoir may be in fluid communication with the valve actuation assembly and in a heat exchange relation to the engine coolant reservoir.
Popeye Project: Hydraulic umbilical
Energy Technology Data Exchange (ETDEWEB)
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...
HYDRAULIC CHARACTERISTICS OF VERTICAL VORTEX AT HYDRAULIC INTAKES
Institute of Scientific and Technical Information of China (English)
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.
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...
Force Analysis and Deformation Calculation of Concentric Double String%同心双管柱受力分析及变形计算
Institute of Scientific and Technical Information of China (English)
刘冰; 綦耀光; 韩军; 王超; 徐春成; 张芬娜; 熊先钺
2013-01-01
The concentric double string has broad prospects of application in oil and gas well downhole operations such as sand washing and acid discharge. The mechanical and mathematical models of concentric double string were established according to hydrodynamic and elastomechanical theories. The influencing factors of the string in operation were considered comprehensively. The calculation method for the string deformation was derived. The calculation shows that the deformation of the string is caused by the effects of pressure difference, submerged weight, frictional force, temperature difference and expansion. The deformation affects the application and safety performance of the string. The actual deformation of the string is less than that of theoretical calculation in practical engineering due to the effects of the friction between casing and string as well as well deflection. When outer tubing shortening and inner tubing lengthening reach a certain value, the inner tubing will undergo buckling deformation. Therefore, the compensation design of string deformation should be conducted.%在油气井冲砂、排酸等井下作业中,同心双管柱具有广阔的应用前景.根据流体力学、弹性力学等理论建立了同心双管柱的力学、数学模型,比较全面地考虑了同心双管柱作业时受到的各种作用因素,推导出同心双管柱变形量的计算方法.计算结果表明,同心双管柱在压差、浮重、摩擦力、温差和膨胀综合作用下发生变形,对其使用和安全性能产生影响；在实际工程中,由于套管和管柱的摩擦作用以及井斜角的影响,同心双管柱的实际变形量要小于理论计算值；当外油管缩短内油管伸长达到一定值时,内油管发生屈曲变形,需要做管柱的变形补偿设计.
Parameter Designing for Heave Compensation Hydraulic System Installed in Deepwater
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
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.
DEFF Research Database (Denmark)
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…
DEFF Research Database (Denmark)
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...
DLC coatings for hydraulic applications
Institute of Scientific and Technical Information of China (English)
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.
Measurement and modeling of unsaturated hydraulic conductivity
Perkins, Kim S.; Elango, Lakshmanan
2011-01-01
The unsaturated zone plays an extremely important hydrologic role that influences water quality and quantity, ecosystem function and health, the connection between atmospheric and terrestrial processes, nutrient cycling, soil development, and natural hazards such as flooding and landslides. Unsaturated hydraulic conductivity is one of the main properties considered to govern flow; however it is very difficult to measure accurately. Knowledge of the highly nonlinear relationship between unsaturated hydraulic conductivity (K) and volumetric water content is required for widely-used models of water flow and solute transport processes in the unsaturated zone. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is common. In hydrologic studies, calculations based on property-transfer models informed by hydraulic property databases are often used in lieu of measured data from the site of interest. Reliance on database-informed predicted values with the use of neural networks has become increasingly common. Hydraulic properties predicted using databases may be adequate in some applications, but not others. This chapter will discuss, by way of examples, various techniques used to measure and model hydraulic conductivity as a function of water content, K. The parameters that describe the K curve obtained by different methods are used directly in Richards’ equation-based numerical models, which have some degree of sensitivity to those parameters. This chapter will explore the complications of using laboratory measured or estimated properties for field scale investigations to shed light on how adequately the processes are represented. Additionally, some more recent concepts for representing unsaturated-zone flow processes will be discussed.
Energy Technology Data Exchange (ETDEWEB)
Freimann, Robert [Muenchen Hochschule (Germany). Fakultaet Bauingenieurwesen
2009-07-01
Hydraulics is the science of the forces of water at rest and in motion. In projects of the water industry, hydraulic calculations provide information for dimensioning structures and plants and for optimising the process that are going on inside. This textbook provides students with sufficient knowledge to solve hydraulic problems and invites them to do their owncalculations. For this, the main hydraulic facts for studies and practice are explained with the aid of calculated examples and problems for the reader to solve. Detailed solutions are provided at the back. The book is full of English terms, which are explained at the back in a glossary. The book addresses students of technical universities and similar institutions, but it may also be a reference manual for the practical engineer. (orig.) [German] Hydraulik ist die Wissenschaft von den Kraeften des ruhenden und des bewegten Wassers. In wasserwirtschaftlichen Planungen dienen die Resultate hydraulischer Berechnungen der Dimensionierung von entsprechenden Bauwerken und Anlagen sowie der Optimierung der darin ablaufenden Prozesse. Dieses Lehrbuch vermittelt den Studierenden das Wissen zur Bearbeitung hydraulischer Fragestellungen und befaehigt sie durch die anschauliche Darstellung zu selbststaendigen Berechnungen. Dabei werden die wichtigsten hydraulischen Zusammenhaenge fuer Studium und Praxis auch mithilfe von durchgerechneten Beispielen und durch den Leser zu loesenden Aufgaben erlaeutert. Zu letzteren sind am Ende des Lehrbuches ausfuehrliche Loesungswege zu finden. Das Buch ist gespickt mit englischen Fachbegriffen rund um die Hydraulik und enthaelt am Ende des Buches ein entsprechendes Verzeichnis. Dieses Buch richtet sich in erster Linie an Studierende des Bauingenieurwesens an Technischen Universitaeten, Fachhochschulen und vergleichbaren Bildungseinrichtungen. Neben der Vermittlung der im Studium erforderlichen Kenntnisse kann es aber auch dem Praktiker eine wertvolle Hilfe zur kurzfristigen
Performances of a balanced hydraulic motor with planetary gear train
Yu, Hongying; Luo, Changjie; Wang, Huimin
2012-07-01
The current research of a balanced hydraulic motor focuses on the characteristics of the motor with three planet gears. References of a balanced hydraulic motor with more than three planet gears are hardly found. In order to study the characteristics of a balanced hydraulic motor with planetary gear train that includes more than three planet gears, on the basis of analysis of the structure and working principle of a balanced hydraulic motor with planetary gear train, formulas are deduced for calculating the hydraulic motor's primary performance indexes such as displacement, unit volume displacement, flowrate fluctuation ratio, etc. Influences of the gears' tooth number on displacement and flowrate characteristics are analyzed. In order to guarantee the reliability of sealing capability, the necessary conditions that tooth number of the sun gear and the planet gears should satisfy are discussed. Selecting large unit volume displacement and small displacement fluctuation ratio as designing objectives, a balanced hydraulic motor with three planet gears and a common gear motor are designed under the conditions of same displacement, tooth addendum coefficien and clearance coefficient. By comparing the unit volume displacement and fluctuation ratio of the two motors, it can be seen that the balanced hydraulic motor with planetary gear train has the advantages of smaller fluctuation ratio and larger unit volume displacement. The results provide theoretical basis for choosing gear tooth-number of this kind of hydraulic motor.
Huang, Xiang; Andrews, Charles B.; Liu, Jie; Yao, Yingying; Liu, Chuankun; Tyler, Scott W.; Selker, John S.; Zheng, Chunmiao
2016-08-01
Understanding the spatial and temporal characteristics of water flux into or out of shallow aquifers is imperative for water resources management and eco-environmental conservation. In this study, the spatial variability in the vertical specific fluxes and hydraulic conductivities in a streambed were evaluated by integrating distributed temperature sensing (DTS) data and vertical hydraulic gradients into an ensemble Kalman filter (EnKF) and smoother (EnKS) and an empirical thermal-mixing model. The formulation of the EnKF/EnKS assimilation scheme is based on a discretized 1D advection-conduction equation of heat transfer in the streambed. We first systematically tested a synthetic case and performed quantitative and statistical analyses to evaluate the performance of the assimilation schemes. Then a real-world case was evaluated to calculate assimilated specific flux. An initial estimate of the spatial distributions of the vertical hydraulic gradients was obtained from an empirical thermal-mixing model under steady-state conditions using a constant vertical hydraulic conductivity. Then, this initial estimate was updated by repeatedly dividing the assimilated specific flux by estimates of the vertical hydraulic gradients to obtain a refined spatial distribution of vertical hydraulic gradients and vertical hydraulic conductivities. Our results indicate that optimal parameters can be derived with fewer iterations but greater simulation effort using the EnKS compared with the EnKF. For the field application in a stream segment of the Heihe River Basin in northwest China, the average vertical hydraulic conductivities in the streambed varied over three orders of magnitude (5 × 10-1 to 5 × 102 m/d). The specific fluxes ranged from near zero (qz < ±0.05 m/d) to ±1.0 m/d, while the vertical hydraulic gradients were within the range of -0.2 to 0.15 m/m. The highest and most variable fluxes occurred adjacent to a debris-dam and bridge pier. This phenomenon is very likely
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.
Study on Thermal-Hydraulic Behavior of an Integral Type Reactor under Heaving Condition
Directory of Open Access Journals (Sweden)
Beibei Feng
2014-01-01
Full Text Available A self-developed program was used to study the thermal-hydraulic behavior of an integral type reactor under heaving condition. Comparison of calculated results with the data of experiments performed on a natural circulation loop designed with reference to an integral type reactor of Tsinghua University in inclination, heaving, and rolling motions was carried out. Characteristics of natural circulation in heaving motion and effect of motion parameters on natural circulation were investigated. Results indicated that: (1 long-period heaving motion would lead to more significant influence than inclination and rolling motion; (2 it was an alternating force field which consisted of gravity and an additional force that decided the flow temperature and density difference of natural circulation; (3 effect of strength k and cycle T of heaving motion on flow fluctuation of natural circulation and condensate depression of heating section outlet was performed.
Energy Technology Data Exchange (ETDEWEB)
Wesolowski, David J [ORNL; Bandura, Andrei V. [St. Petersburg State University, St. Petersburg, Russia; Sofo, Jorge O. [Pennsylvania State University; Kubicki, James D. [Pennsylvania State University
2006-01-01
Plane-wave density functional theory (DFT-PW) calculations were performed on bulk SnO{sub 2} (cassiterite) and the (100), (110), (001), and (101) surfaces with and without H{sub 2}O present. A classical interatomic force field has been developed to describe bulk SnO{sub 2} and SnO{sub 2}-H{sub 2}O surface interactions. Periodic density functional theory calculations using the program VASP (Kresse et al., 1996) and molecular cluster calculations using Gaussian 03 (Frisch et al., 2003) were used to derive the parametrization of the force field. The program GULP (Gale, 1997) was used to optimize parameters to reproduce experimental and ab initio results. The experimental crystal structure and elastic constants of SnO{sub 2} are reproduced reasonably well with the force field. Furthermore, surface atom relaxations and structures of adsorbed H{sub 2}O molecules agree well between the ab initio and force field predictions. H{sub 2}O addition above that required to form a monolayer results in consistent structures between the DFT-PW and classical force field results as well.
Directory of Open Access Journals (Sweden)
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
ELECTRO-HYDRAULIC SERVO SYSTEM IN THE CENTRIFUGE FIELD
Institute of Scientific and Technical Information of China (English)
Dong Longlei; Yan Guirong; Li Ronglin
2004-01-01
The mechanical characteristics of the electro-hydraulic servo system in the centrifuge field are analyzed.The hydraulic pressure law in the centrifuge field indicates the existence of the centrifuge hydraulic pressure.The mechanical characteristics of the slide-valve and the dual nozzle flapper valve are studied,and it is found that the centrifuge field can not only increase the driving force or moment of the function units,but also decrease the stability of the components.Finally by applying Gauss minimum constraint principle,the dynamic model of the electro-hydraulic vibrator in the centrifuge field is established,and the mechanical restriction of the system is also presented.The study will be helpful for the realization of the combined vibration and centrifuge test system.
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...
Goicochea, A Gama; Hernández, J D; Pérez, E
2014-01-01
The role of viscous forces coupled with Brownian forces in momentum conserving computer simulations is studied here in the context of their contribution to the total average pressure of a simple fluid as derived from the virial theorem, in comparison with the contribution of the conservative force to the total pressure. The specific mesoscopic model used is the one known as dissipative particle dynamics, although our conclusions apply to similar models that obey the fluctuation dissipation theorem for short range interactions and have velocity dependent viscous forces. We find that the average contribution of the random and dissipative forces to the pressure is negligible for long simulations, provided these forces are appropriately coupled and when the finite time step used in the integration of the equation of motion is not too small. Finally, we study the properties of the fluid when the random force is made equal to zero and find that the system freezes as a result of the competition of the dissipative an...
Huang, Bingxiang; Li, Pengfeng; Ma, Jian; Chen, Shuliang
2014-07-01
Because of the advantages of integrating water pressure blasting and hydraulic fracturing, the use of hydraulic fracturing after water pressure control blasting is a method that is used to fully transform the structure of a coal-rock mass by increasing the number and range of hydraulic cracks. An experiment to study hydraulic fracturing after water pressure blasting on cement mortar samples (300 × 300 × 300 mm3) was conducted using a large-sized true triaxial hydraulic fracturing experimental system. A traditional hydraulic fracturing experiment was also performed for comparison. The experimental results show that water pressure blasting produces many blasting cracks, and follow-up hydraulic fracturing forces blasting cracks to propagate further and to form numerous multidirectional hydraulic cracks. Four macroscopic main hydraulic cracks in total were noted along the borehole axial and radial directions on the sample surfaces. Axial and radial main failure planes induced by macroscopic main hydraulic cracks split the sample into three big parts. Meanwhile, numerous local hydraulic cracks were formed on the main failure planes, in different directions and of different types. Local hydraulic cracks are mainly of three types: local hydraulic crack bands, local branched hydraulic cracks, and axial layered cracks. Because local hydraulic cracks produce multiple local layered failure planes and lamellar ruptures inside the sample, the integrity of the sample decreases greatly. The formation and propagation process of many multidirectional hydraulic cracks is affected by a combination of water pressure blasting, water pressure of fracturing, and the stress field of the surrounding rock. To a certain degree, the stress field of surrounding rock guides the formation and propagation process of the blasting crack and the follow-up hydraulic crack. Following hydraulic fracturing that has been conducted after water pressure blasting, the integrity of the sample is found to
Modeling and controlling of a flexible hydraulic manipulator
Institute of Scientific and Technical Information of China (English)
LI Guang; WU Min
2005-01-01
A mathematical model was developed combining the dynamics of an Euler-Bernoulli beam, described by the assumed-mode method and hydraulic circuit dynamics. Only one matrix, termed drive Jacobian, was needed in the modeling of interaction between hydraulic circuit and flexible manipulator mechanism. Furthermore, a new robust controller based on mentioned above dynamic model was also considered to regulate both flexural vibrations and rigid body motion. The proposed controller combined sliding mode and backstepping techniques to deal with the nonlinear system with uncertainties. The sliding mode control was used to achieve an asymptotic joint angle and vibration regulation by providing a virtual force while the backstepping technique was used to regulate the spool position of a hydraulic valve to provide the required control force. Simulation results are presented to show the stabilizing effect and robustness of this control strategy.
Energy Technology Data Exchange (ETDEWEB)
Glaeser, H.; Graf, U.; Herb, J.; and others
2012-02-15
The project RS1184 „Thermal-hydraulic Calculation Methods for Transients and Accidents of the Reactor Cooling System Under Special Consideration of Multi-Dimensional Flows (ATHLET, FLUBOX, CFX)'' consists of four work packages: 1. Further development of the computer code ATHLET 2. Termination of FLUBOX development and development of an ATHLET-internal 3D module 3. Coupling of ATHLET and CFD code ANSYS CFX as well as CFX model development to simulate three-dimensional flows in the reactor coolant system 4. Prediction capability of computer code ATHLET. One of the superior objectives of the project is to improve the prediction capability of the thermal-hydraulic system code ATHLET, including the simulation of multi-dimensional flow in the reactor vessel. The constitutive equations in ATHLET, especially the momentum equations in ATHLET, are written in one-dimensional form. It was planned to develop the 2D/3D module FLUBOX further and couple it with ATHLET. Due to reasons given in chapter 3, the FLUBOX development was terminated. Instead, the decision was made to develop a fast running internal ATHLET-module. The 2D/3D equations for ATHLET have been derived and were implemented. That strategy allows using all ATHLET models and the ATHLET code structure. An additional advantage is that different numerical schemes of different codes, and consequently a loss of efficiency, will be avoided. A second possibility is the coupling of ATHLET with the CFD code ANSYS CFX. Such a coupled code system will be used in those cases when a part of the simulation area is needed to be calculated with high resolution. Such a detailed modelling cannot be provided by ATHLET-3D. A complete representation of the cooling system by a CFD code cannot be performed due to calculation time. In order to calculate the complete system behavior still with ATHLET, that part to be investigated in more detail, will be replaced by a CFX model. Several new models and improvements of existing
MODELING AND CALCULATION OF FLOW AMPLIFIER PARAMETERS IN STEERING OF HEAVY TRUCKS
Directory of Open Access Journals (Sweden)
V. P. Avtushko
2008-01-01
Full Text Available The paper analyzes prospects pertaining to development of methods for dynamic calculation of monitoring hydraulic units with various types of relations. Calculated diagram of steering hydraulic drive with flow amplifier and turning cylinder has been given in the paper and its dynamic model has been developed. A hydraulic drive is considered as a system with lumped parameters. It is supposed that properties of working fluid are unchangeable during transient process; leakages and cavitations do not occur; fluid can be pressed; resistance of service drain line is taken into account. Model has been developed with due account of resistance of manifolds and internal channels of flow amplifier, hydrodynamic forces, that influence on amplifier control valves, and friction forces of movable elements. Multi-variant dynamic calculation has been done and some results of the investigations are presented in the paper. The paper also contains analysis that shows influence of various design and component parameters of flow amplifier on the drive dynamics.
DEFF Research Database (Denmark)
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....
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.
New parameters influencing hydraulic runner lifetime
Sabourin, M.; Thibault, D.; Bouffard, D. A.; Lévesque, M.
2010-08-01
Traditionally, hydraulic runner mechanical design is based on calculation of static stresses. Today, validation of hydraulic runner design in terms of reliability requires taking into account the fatigue effect of dynamics loads. A damage tolerant approach based on fracture mechanics is the method chosen by Alstom and Hydro-Québec to study fatigue damage in runners. This requires a careful examination of all factors influencing material fatigue behavior. Such material behavior depends mainly on the chemical composition, microstructure and thermal history of the component, and on the resulting residual stresses. Measurement of fracture mechanics properties of various steels have demonstrated that runner lifetime can be significantly altered by differences in the manufacturing process, although remaining in accordance with agreed practices and standards such as ASTM. Carbon content and heat treatment are suspected to influence fatigue lifetime. This will have to be investigated by continuing the current research.
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...
Institute of Scientific and Technical Information of China (English)
杨磊磊
2014-01-01
Based on computational fluid dynamics, and using three-dimensional river hydraulic model HEC-RAS ( River Analyse System) , this paper took the interchange bridge No. 2 as the research object, which is situated on the Bejaia Express Highway in Algeria and was still under construction. Meanwhile, under the same geological condition and with once-in-a-hundred-year flood peak flow, the paper analyzed the influences of different bridge span schemes on the maximum bridge scouring depth. And then in this paper, the calculation results of three-dimensional river hydraulic model under the condition of different bridge span schemes were analyzed and researched, and finally an economical and reasonable bridge design scheme was determined. This paper provides a new research approach of scheme design for similar bridges at home and abroad in future.%基于计算流体动力学的方法，运用三维河道水力学模型HEC-RAS( River Analyse System)分析阿尔及利贝贾亚高速公路在建项目2号互通桥梁在百年一遇的最大洪峰流量下，不同桥梁孔跨方案在相同地质条件下对桥梁最大冲刷深度的影响，对不同桥梁孔跨方案下三维河道水力学模型计算结果进行分析研究，确定经济合理的桥梁设计方案，为今后国内外同类桥梁设计的方案研究提供了新的研究方法。
Institute of Scientific and Technical Information of China (English)
王荀; 邱阿瑞
2012-01-01
In this paper, the field-circuit coupled time-stepping finite element model of squirrel-cage asynchronous motor is presented and the validity is verified by means of the comparison between the stator phase current harmonics of the simulating wave and those of the experiment wave. Air gap flux density is calculated by means of this model and radial electromagnetic force is calculated using the classical Maxwell stress tensor method. Air gap flux density and radial electromagnetic force vary in both space domain and time domain and two dimensional Fourier analysis are carried out to calculate harmonics of those. The influence of the tooth and slot and the slip on flux density and radial electromagnetic force are discussed. The relationship of flux density waves and radial electromagnetic force waves are analyzed. Radial electromagnetic force waves and the testing electromagnetic noise spectra are analyzed and compared and the results verify the effectiveness of the calculation of radial electromagnetic force waves. Radial electromagnetic force and its harmonics calculated by the method can be used to electromagnetic noise analysis in the design stage.%建立笼型异步电动机的场路耦合时步有限元模型,通过定子相电流仿真波形和实测波形的谐波比较验证有效性。基于该模型计算气隙磁通密度,进而利用经典的Maxwell应力张量法计算径向电磁力。气隙磁通密度和径向电磁力均随空间和时间变化,利用二维傅里叶分析分别求解它们的谐波;并探讨齿槽和转差率对磁通密度和径向电磁力的影响,以及磁通密度波和径向电磁力波之间的关系。将径向电磁力波和实测电磁噪声频谱进行了分析和对比,结果表明径向电磁力波的计算是合理有效的。利用本文方法计算的径向电磁力及其谐波可应用于在设计阶段对电磁噪声的分析。
Institute of Scientific and Technical Information of China (English)
张云鹏; 刘淑琴; 李红伟; 范友鹏
2012-01-01
研究轴向混合磁轴承实现五自由度悬浮时，需要计算径向承载力与磁轴承结构参数以及永磁体参数之间的关系。为了解决轴向混合磁轴承缺乏径向承载力解析数学模型的问题，该文在分析轴向混合磁轴承磁路以及各部分磁导的基础上，结合稀土永磁体的工作特性，用虚位移法得出了轴向混合磁轴承的径向承载力解析数学模型。模型表明，在小径向位移时，该型的混合磁轴承径向承载力随着径向位移增加而增加，近似线性关系，径向承载力和刚度随轴向气隙增大而减小；磁轴承径向承载力随永磁体的有效长度增加呈现先增大后趋近饱和。利用有限元方法对径向承载力进行仿真计算，仿真结果与模型计算结果基本吻合。%In studying axial hybrid magnetic bearing （HMB） for suspension in five degree of freedom （DOF）, the relationship between radial electromagnetic force and magnetic bearing structural parameters and permanent magnet parameters should be calculated. In order to overcome the lack of analytical calculation model for radial electromagnet force of axial HMB, based on magnetic circuit analysis and calculation of magnetic conductance for each parts, the analytical calculation model for radial electromagnet force of axial HMB is proposed in this paper. The analytical formulation of radial electromagnetic force is derived by using virtual displacement method and demagnetization characteristics of the rare earth permanent magnet. It is found that the radial electromagnetic force increases with the radial displacement increasing approximately in linear relationship, and the radial force and stiffness decreases with the axial gap increasing. The radial electromagnetic force increased and then saturated with increasing permanent magnet effective length. The model of axial HMB is simulated by finite-element method software and the simulation results are basically in
AN ANALYTICAL SOLUTION FOR CALCULATING THE INITIATION OF SEDIMENT MOTION
Institute of Scientific and Technical Information of China (English)
Thomas LUCKNER; Ulrich ZANKE
2007-01-01
This paper presents an analytical solution for calculating the initiation of sediment motion and the risk of river bed movement. It thus deals with a fundamental problem in sediment transport, for which no complete analytical solution has yet been found. The analytical solution presented here is based on forces acting on a single grain in state of initiation of sediment motion. The previous procedures for calculating the initiation of sediment motion are complemented by an innovative combination of optical surface measurement technology for determining geometrical parameters and their statistical derivation as well as a novel approach for determining the turbulence effects of velocity fluctuations. This two aspects and the comparison of the solution functions presented here with the well known data and functions of different authors mainly differ the presented solution model for calculating the initiation of sediment motion from previous approaches. The defined values of required geometrical parameters are based on hydraulically laboratory tests with spheres. With this limitations the derivated solution functions permit the calculation of the effective critical transport parameters of a single grain, the calculation of averaged critical parameters for describing the state of initiation of sediment motion on the river bed, the calculation of the probability density of the effective critical velocity as well as the calculation of the risk of river bed movement. The main advantage of the presented model is the closed analytical solution from the equilibrium of forces on a single grain to the solution functions describing the initiation of sediment motion.
Wave Dragon. Test to evaluate hydraulic response. Report phase A
Energy Technology Data Exchange (ETDEWEB)
Soerensen, H.C.; Friis-Madsen, E.
1999-02-01
Danish Maritime Institute has in the spring 1998 built a model in scale 1:50 of the wave energy converter Wave Dragon. The scale model is based on calculations performed by the inventor Erik Friis-Madsen from the consultant Loewenmark F.R.I. The scale model is tested in the wave tank at Aalborg University, the Hydraulic and Coastal Engineering Laboratory. This report deals with the results from this test (phase A of the test program). The objective of the test series was to get a judgement of the viability of Wave Dragon in extreme sea conditions in the Danish part of the North Sea at a water depth of 30 meters. The test series had to document: The viability of the Wave Dragon in extreme sea conditions up to 100-year waves; the hydraulic response in 7 different sea conditions where forces and movements have been registered. The main findings are: Wave Dragon has the expected behavior, i.e. the converter is able to survive a 100-year storm; An adjustment of the pitch of the converter could improve the energy efficiency; The forces in the mooring system and the junction between wave reflectors and the platform are acceptable. The forces and the movements are registered at 7 different sea conditions. Video recording has been taken during the test. Five of the sea conditions correspond to 'normal' waves in which power will be produced. Two sea conditions correspond to extreme wave situations. The duration of the registration in each sea conditions was approximately 1/2 an hour, i.e. 3.5 hours in scale 1:1. The conclusion is: The planned test series to evaluate the energy performance can start up (phase B of the test program); The energy efficiency is expected to be improved by a slight modification in the geometry of the Wave Dragon. The modifications can include the geometry of the front and the stabilising wing at the rear end of the platform. Further on changes are possible in the stiffness of the junction between the wave reflectors and the platform and
Spatial variability in streambed hydraulic conductivity of contrasting stream morphologies
DEFF Research Database (Denmark)
Sebök, Éva; Calvache, Carlos Duque; Engesgaard, Peter Knudegaard;
2015-01-01
Streambed hydraulic conductivity is one of the main factors controlling variability in surface water-groundwater interactions, but only few studies aim at quantifying its spatial and temporal variability in different stream morphologies. Streambed horizontal hydraulic conductivities (Kh) were...... therefore determined from in-stream slug tests, vertical hydraulic conductivities (Kv) were calculated with in-stream permeameter tests and hydraulic heads were measured to obtain vertical head gradients at eight transects, each comprising five test locations, in a groundwater-dominated stream. Seasonal...... small-scale measurements were taken in December 2011 and August 2012, both in a straight stream channel with homogeneous elevation and downstream of a channel meander with heterogeneous elevation. All streambed attributes showed large spatial variability. Kh values were the highest at the depositional...
Determination of Material Strengths by Hydraulic Bulge Test
Directory of Open Access Journals (Sweden)
Hankui Wang
2016-12-01
Full Text Available The hydraulic bulge test (HBT method is proposed to determine material tensile strengths. The basic idea of HBT is similar to the small punch test (SPT, but inspired by the manufacturing process of rupture discs—high-pressure hydraulic oil is used instead of punch to cause specimen deformation. Compared with SPT method, the HBT method can avoid some of influence factors, such as punch dimension, punch material, and the friction between punch and specimen. A calculation procedure that is entirely based on theoretical derivation is proposed for estimate yield strength and ultimate tensile strength. Both conventional tensile tests and hydraulic bulge tests were carried out for several ferrous alloys, and the results showed that hydraulic bulge test results are reliable and accurate.
Determination of Material Strengths by Hydraulic Bulge Test.
Wang, Hankui; Xu, Tong; Shou, Binan
2016-12-30
The hydraulic bulge test (HBT) method is proposed to determine material tensile strengths. The basic idea of HBT is similar to the small punch test (SPT), but inspired by the manufacturing process of rupture discs-high-pressure hydraulic oil is used instead of punch to cause specimen deformation. Compared with SPT method, the HBT method can avoid some of influence factors, such as punch dimension, punch material, and the friction between punch and specimen. A calculation procedure that is entirely based on theoretical derivation is proposed for estimate yield strength and ultimate tensile strength. Both conventional tensile tests and hydraulic bulge tests were carried out for several ferrous alloys, and the results showed that hydraulic bulge test results are reliable and accurate.
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...
Stark, Austin C; Andrews, Casey T; Elcock, Adrian H
2013-09-10
Coarse-grained (CG) simulation methods are now widely used to model the structure and dynamics of large biomolecular systems. One important issue for using such methods - especially with regard to using them to model, for example, intracellular environments - is to demonstrate that they can reproduce experimental data on the thermodynamics of protein-protein interactions in aqueous solutions. To examine this issue, we describe here simulations performed using the popular coarse-grained MARTINI force field, aimed at computing the thermodynamics of lysozyme and chymotrypsinogen self-interactions in aqueous solution. Using molecular dynamics simulations to compute potentials of mean force between a pair of protein molecules, we show that the original parameterization of the MARTINI force field is likely to significantly overestimate the strength of protein-protein interactions to the extent that the computed osmotic second virial coefficients are orders of magnitude more negative than experimental estimates. We then show that a simple down-scaling of the van der Waals parameters that describe the interactions between protein pseudo-atoms can bring the simulated thermodynamics into much closer agreement with experiment. Overall, the work shows that it is feasible to test explicit-solvent CG force fields directly against thermodynamic data for proteins in aqueous solutions, and highlights the potential usefulness of osmotic second virial coefficient measurements for fully parameterizing such force fields.
Linke, Bernd; Muha, Ivo; Wittum, Gabriel; Plogsties, Vincent
2013-02-01
Data from 24 full scale biogas plants in Germany digesting cow manure and crops were evaluated. Special emphasis was given to the effect of hydraulic retention time HRT and proportion of crops in the mixture (VS basis) p(VS,Crops)(Inp) on the methane yield from the digester [Formula: see text] and the storage tank [Formula: see text] at 37 and 22°C. The evaluation has shown model parameters for maximal methane yield of manure and crops [Formula: see text] at 270 and 420 Lkg(-1), respectively. For example, at HRT of 60days, maximum methane yield result to 249 and 388 Lkg(-1) for a crop proportion in the input of 0.0 and 1.0, respectively. The calculation of [Formula: see text] considers first order reaction rates and a temperature term f(T). Hence, at any arbitrary temperature in the range of 12°C
2007-03-01
Base, the A-10 depot maintenance, commodities, and backshop workloads previously located in Sacramento were relocated to the Hill AFB hydraulic and...Air Force Base, the A-10 depot maintenance, commodities, and backshop workloads previously located in Sacramento were relocated to the Hill AFB ...relocating the hydraulic and pneudraulic repair facility to another Air Force base. Since workload has already been located from McClellan AFB , and
Nonlinear, Adaptive and Fault-tolerant Control for Electro-hydraulic Servo Systems
DEFF Research Database (Denmark)
Choux, Martin
Fluid power systems have been in use since 1795 with the rst hydraulic press patented by Joseph Bramah and today form the basis of many industries. Electro hydraulic servo systems are uid power systems controlled in closed-loop. They transform reference input signals into a set of movements...... in hydraulic actuators (cylinders or motors) by the means of hydraulic uid under pressure. With the development of computing power and control techniques during the last few decades, they are used increasingly in many industrial elds which require high actuation forces within limited space. However, despite...... numerous attractive properties, hydraulic systems are always subject to potential leakages in their components, friction variation in their hydraulic actuators and deciency in their sensors. These violations of normal behaviour reduce the system performances and can lead to system failure...
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…
Institute of Scientific and Technical Information of China (English)
李琪; 张铁军; 于继良
2004-01-01
文章介绍了正在研制的调制式旋转导向钻井工具MRST的组成及其工作原理;它由测控短节、偏置导向执行机构两大部分组成,是在钻柱全旋转且相对于井壁没有静止支撑点的条件下进行导向钻井的.工具偏置导向执行机构的执行是以钻井液为制导动力源,即作用在执行机构伸缩块上的内外压差而产生的液力推力,液力推力的大小与制导效果密切相关;为此,采用常规钻井水力学计算程序,对MRST在正常钻井工作条件下液力推力的大小及其影响因素进行了计算分析.结果表明,就目前国内陆上钻井设备所具有的条件,所研制的MRST是可以适应7000 m井深以内的井对导向力控制要求的;但作用在MRST伸缩块上的液力推力是随井深、排量、钻井液密度及流变性等的变化而变化的,实际应用MRST时应考虑上述因素变化对MRST工作性能产生的影响;此外,也可考虑通过微调排量的办法来调整MRST导向力的大小.
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
Hydraulic Stability of Accropode Armour
DEFF Research Database (Denmark)
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
DEFF Research Database (Denmark)
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...
DEFF Research Database (Denmark)
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...
HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM
Directory of Open Access Journals (Sweden)
O. M. Pshinko
2015-08-01
Full Text Available Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canonical equations consists of the equations for concrete strength, absolute volume, concrete mix consistency as well as the equation for optimal concrete saturation with aggregates while minimizing cement content. The joint solution of these four equations related to composition allows determining for the materials the concrete composition of required strength, concrete workability with minimum cement content. The procedure for calculation of hydraulic concrete composition according to the physico-analytical method consists of two parts: 1 physical, which is laboratory testing of concrete mix components in different concrete compositions; 2 analytical, which represents the calculation algorithm for concrete compositions equivalent in concrete strength and workability that comply with the specific conditions of concrete placing. Findings. To solve the problem of designing the concrete composition with the desired properties for railway structures and buildings it was proposed to use the information technology in the form of a developed computer program whose algorithm includes the physico-analytical method for hydraulic concrete composition determination. Originality. The developed concrete composition design method takes into account the basic properties of raw materials, concrete mix and concrete, which are pre-determined. The distinctive feature of physico-analytical method is obtaining of a set of equivalent compositions with a certain concrete mix
Flow characteristics of variable hydraulic transformer
Institute of Scientific and Technical Information of China (English)
杨冠中; 姜继海
2015-01-01
A new kind of hydraulic transformer, called variable hydraulic transformer (VHT), is proposed to control its load flow rate. The hydraulic transformer evolves from a pressure transducer to a power transducer. The flow characteristics of VHT, such as its instantaneous flow rates, average flow rates, and flow pulsations in the ports, are investigated. Matlab software is used to simulate and calculate. There are five controlled angles of the port plate that can help to define the flow characteristics of VHT. The relationships between the flow characteristics and the structure in VHT are shown. Also, the plus−minus change of the average flow rates and the continuity of the instantaneous flow rates in the ports are presented. The results demonstrate the performance laws of VHT when the controlled angles of the port plate and of the swash plate change. The results also reveal that the special principle of the flow pulsation in the ports and the jump points of the instantaneous curves are the two basic causes of its loud noise, and that the control angles of the port plate and the swash plate and the pressures in the ports are the three key factors of the noise.
Directory of Open Access Journals (Sweden)
F. Raes
2004-12-01
Full Text Available To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH4, carbon monoxide (CO, non-methane volatile organic compounds (NMVOC and nitrogen oxides (NOx up to the year 2030 and implemented them in two global Chemistry Transport Models. The "Current Legislation" (CLE scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a "Maximum technically Feasible Reduction" (MFR scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NOx, NMVOC and CO than was suggested by the widely used IPCC (Intergovernmental Panel on Climate Change SRES (Special Report on Emission Scenarios scenarios (Nakicenovic et al., 2000. With the TM3 and STOCHEM models we performed several long-term integrations (1990–2030 to assess global, hemispheric and regional changes in CH4, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce realistically the observed trends in background ozone, CO, and CH4 concentrations from 1990 to 2002. For the "current legislation" case, both models indicate an increase of the annual average ozone levels in the Northern hemisphere by 5 ppbv, and up to 15 ppbv over the Indian
Tidal modulation of two-layer hydraulic exchange flows
Directory of Open Access Journals (Sweden)
L. M. Frankcombe
2006-11-01
Full Text Available Time-dependent, two layer hydraulic exchange flow is studied using an idealised shallow water model. It is found that barotropic time-dependent perturbations, representing tidal forcing, increase the baroclinic exchange flux above the steady hydraulic limit, with flux increasing monotonically with tidal amplitude (measured either by height or flux amplitude over a tidal period. Exchange flux also depends on the non-dimensional tidal period, γ, which was introduced by Helfrich (1995. Resonance complicates the relationship between exchange flux and height amplitude, but, when tidal strength is characterised by flux amplitude, exchange flux is a monotonic function of γ.
Institute of Scientific and Technical Information of China (English)
邓先华; 简文星
2015-01-01
structure and anchor cable tensile force. It establishes anchor cable tensile force matching with the cost of pile-anchor cable structure calculation models from three aspects of relation curve model,polynomial fitting model and optimized deformation consistence condition model.It combines“m”and “K”methods of pile internal force calculation and structural mechanics’principle of virtual work and diagram multiplication method.A calculation programs by Visual C++is complied to calculate the cost of pile-anchor cable structure with different anchor cable tensile force through different case studies.It presents the relation diagrams between the cost of pile-anchor cable structure and anchor cable tensile force.The results show that the cost of pile-anchor cable structure first decreases and then increases with the increase of anchor cable tensile force.Three kinds of model calculation results of anchor cable tensile force matching with the cost of pile-anchor cable structure are very close.Anchor cable tensile force calculated by any method can be considered as the final anchor cable tensile force design value.At this point,the plus and minus extremums of bending moment of pile are not equal.This also shows that anchor cable tensile force is not necessarily the optimal when the plus and minus extremums of bending moment of pile are equal.Although pile body status is ideal at the moment,the cost may be higher,so that economic benefit is poor.
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
Institute of Scientific and Technical Information of China (English)
Yue JIN; Yang LU; Jiahui GONG; Zhixiong LU; Wenming LI; Jungan WU
2015-01-01
An Electro-hydraulic loading system is designed based on a test-bed of tractor’s hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force is controlled to make proportional and continuous variable by an electro-hydraulic proportional relief valve. A steering resistance loading test-bed is built to test three kinds of steering resistance including constant,step and sine style. Tire lateral resistance is also tested under different steering conditions. The result shows that the electro-hydraulic loading system has high stability and following performance. Besides,the system’s steady state error is lower than 3. 1%,and it meets the test requirement of tractor’s hydraulic steering by-wire.
Global dynamic modeling of electro-hydraulic 3-UPS/S parallel stabilized platform by bond graph
Zhang, Lijie; Guo, Fei; Li, Yongquan; Lu, Wenjuan
2016-08-01
Dynamic modeling of a parallel manipulator(PM) is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.
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.
Directory of Open Access Journals (Sweden)
F. Dentener
2005-01-01
Full Text Available To explore the relationship between tropospheric ozone and radiative forcing with changing emissions, we compiled two sets of global scenarios for the emissions of the ozone precursors methane (CH4, carbon monoxide (CO, non-methane volatile organic compounds (NMVOC and nitrogen oxides (NOx up to the year 2030 and implemented them in two global Chemistry Transport Models. The 'Current Legislation' (CLE scenario reflects the current perspectives of individual countries on future economic development and takes the anticipated effects of presently decided emission control legislation in the individual countries into account. In addition, we developed a 'Maximum technically Feasible Reduction' (MFR scenario that outlines the scope for emission reductions offered by full implementation of the presently available emission control technologies, while maintaining the projected levels of anthropogenic activities. Whereas the resulting projections of methane emissions lie within the range suggested by other greenhouse gas projections, the recent pollution control legislation of many Asian countries, requiring introduction of catalytic converters for vehicles, leads to significantly lower growth in emissions of the air pollutants NOx, NMVOC and CO than was suggested by the widely used and more pessimistic IPCC (Intergovernmental Panel on Climate Change SRES (Special Report on Emission Scenarios scenarios (Nakicenovic et al., 2000, which made Business-as-Usual assumptions regarding emission control technology. With the TM3 and STOCHEM models we performed several long-term integrations (1990-2030 to assess global, hemispheric and regional changes in CH4, CO, hydroxyl radicals, ozone and the radiative climate forcings resulting from these two emission scenarios. Both models reproduce broadly the observed trends in CO, and CH4 concentrations from 1990 to 2002. For the 'current legislation' case, both models indicate an increase of the annual average ozone
Hydraulic Actuators with Autonomous Hydraulic Supply for the Mainline Aircrafts
Directory of Open Access Journals (Sweden)
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
Energy Technology Data Exchange (ETDEWEB)
Morgado, Claudio A.; Jurecka, Petr; Svozil, Daniel; Hobza, Pavel; Sponer, Jiri
2009-06-09
We have carried out reference quantum-chemical calculations for about 100 geometries of the uracil dimer in stacked conformations. The calculations have been specifically aimed at geometries with unoptimized distances between the monomers including geometries with mutually tilted monomers. Such geometries are characterized by a delicate balance between local steric clashes and local unstacking and had until now not been investigated using reference quantummechanics (QM) methods. Nonparallel stacking geometries often occur in nucleic acids and are of decisive importance, for example, for local conformational variations in B-DNA. Errors in the shortrange repulsion region would have a major impact on potential energy scans which were often used in the past to investigate local geometry variations in DNA. An incorrect description of such geometries may also partially affect molecular dynamics (MD) simulations in applications when quantitative accuracy is required. The reference QM calculations have been carried out using the MP2 method extrapolated to the complete basis-set limit and corrected for higher-order electron-correlation contributions using CCSD(T) calculations with a medium-sized basis set. These reference calculations have been used as benchmark data to test the performance of the DFT-D, SCS(MI)-MP2, and DFTSAPT QM methods and of the AMBER molecular-mechanics (MM) force field. The QM methods show close to quantitative agreement with the reference data, albeit the DFT-D method tends to modestly exaggerate the repulsion of steric clashes. The force field in general also provides a good description of base stacking for the systems studied here. However, for geometries with close interatomic contacts and clashes, the repulsion effects are rather severely exaggerated. The discrepancy reported here should not affect the overall stability of MD simulations and qualitative applications of the force field. However, it may affect the description of subtle
Hydraulic conductivity of organomodified soil
Energy Technology Data Exchange (ETDEWEB)
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.
Performance optimization of grooved slippers for aero hydraulic pumps
Institute of Scientific and Technical Information of China (English)
Chen Juan; Ma Jiming; Li Jia; Fu Yongling
2016-01-01
A computational fluid dynamics (CFD) simulation method based on 3-D Navier–Stokes equation and Arbitrary Lagrangian–Eulerian (ALE) method is presented to analyze the grooved slip-per performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry (groove width and radius, orifice size) on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.
Performance optimization of grooved slippers for aero hydraulic pumps
Directory of Open Access Journals (Sweden)
Juan Chen
2016-06-01
Full Text Available A computational fluid dynamics (CFD simulation method based on 3-D Navier–Stokes equation and Arbitrary Lagrangian–Eulerian (ALE method is presented to analyze the grooved slipper performance of piston pump. The moving domain of grooved slipper is transformed into a fixed reference domain by the ALE method, which makes it convenient to take the effects of rotate speed, body force, temperature, and oil viscosity into account. A geometric model to express the complex structure, which covers the orifice of piston and slipper, vented groove and the oil film, is constructed. Corresponding to different oil film thicknesses calculated in light of hydrostatic equilibrium theory and boundary conditions, a set of simulations is conducted in COMSOL to analyze the pump characteristics and effects of geometry (groove width and radius, orifice size on these characteristics. Furthermore, the mechanics and hydraulics analyses are employed to validate the CFD model, and there is an excellent agreement between simulation and analytical results. The simulation results show that the sealing land radius, orifice size and groove width all dramatically affect the slipper behavior, and an optimum tradeoff among these factors is conducive to optimizing the pump design.
Inconsistency in the average hydraulic models used in nuclear reactor design and safety analysis
Energy Technology Data Exchange (ETDEWEB)
Park, Jee Won; Roh, Gyu Hong; Choi, Hang Bok [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)
1997-12-31
One of important inconsistencies in the six-equation model predictions has been found to be the force experienced by a single bubble placed in a convergent stream of liquid. Various sets of governing equations yield different amount of forces to hold the bubble stationary in a convergent nozzle. By using the first order potential flow theory, it is found that the six-equation model can not be used to estimate the force experienced by a deformed bubble. The theoretical value of the particle stress of a bubble in a convergent nozzle flow has been found to be a function of the Weber number when bubble distortion is allowed. This force has been calculated by using different sets of governing equations and compared with the theoretical value. It is suggested in this study that the bubble size distribution function can be used to remove the presented inconsistency by relating the interfacial variables with different moments of the bubble size distribution function. This study also shows that the inconsistencies in the thermal-hydraulic governing equation can be removed by mechanistic modeling of the phasic interface. 11 refs., 3 figs. (Author)
A Coupled Calculation Suite for Atucha II Operational Transients Analysis
Directory of Open Access Journals (Sweden)
Oscar Mazzantini
2011-01-01
Full Text Available While more than a decade ago reactor and thermal hydraulic calculations were tedious and often needed a lot of approximations and simplifications that forced the designers to take a very conservative approach, computational resources available nowadays allow engineers to cope with increasingly complex problems in a reasonable time. The use of best-estimate calculations provides tools to justify convenient engineering margins, reduces costs, and maximises economic benefits. In this direction, a suite of coupled best-estimate specific calculation codes was developed to analyse the behaviour of the Atucha II nuclear power plant in Argentina. The developed tool includes three-dimensional spatial neutron kinetics, a channel-level model of the core thermal hydraulics with subcooled boiling correlations, a one-dimensional model of the primary and secondary circuits including pumps, steam generators, heat exchangers, and the turbine with all their associated control loops, and a complete simulation of the reactor control, limitation, and protection system working in closed-loop conditions as a faithful representation of the real power plant. In the present paper, a description of the coupling scheme between the codes involved is given, and some examples of their application to Atucha II are shown.
Baker, Christopher M; Lopes, Pedro E M; Zhu, Xiao; Roux, Benoît; Mackerell, Alexander D
2010-03-01
Lennard-Jones (LJ) parameters for a variety of model compounds have previously been optimized within the CHARMM Drude polarizable force field to reproduce accurately pure liquid phase thermodynamic properties as well as additional target data. While the polarizable force field resulting from this optimization procedure has been shown to satisfactorily reproduce a wide range of experimental reference data across numerous series of small molecules, a slight but systematic overestimate of the hydration free energies has also been noted. Here, the reproduction of experimental hydration free energies is greatly improved by the introduction of pair-specific LJ parameters between solute heavy atoms and water oxygen atoms that override the standard LJ parameters obtained from combining rules. The changes are small and a systematic protocol is developed for the optimization of pair-specific LJ parameters and applied to the development of pair-specific LJ parameters for alkanes, alcohols and ethers. The resulting parameters not only yield hydration free energies in good agreement with experimental values, but also provide a framework upon which other pair-specific LJ parameters can be added as new compounds are parametrized within the CHARMM Drude polarizable force field. Detailed analysis of the contributions to the hydration free energies reveals that the dispersion interaction is the main source of the systematic errors in the hydration free energies. This information suggests that the systematic error may result from problems with the LJ combining rules and is combined with analysis of the pair-specific LJ parameters obtained in this work to identify a preliminary improved combining rule.
Method to Estimate the Dissolved Air Content in Hydraulic Fluid
Hauser, Daniel M.
2011-01-01
In order to verify the air content in hydraulic fluid, an instrument was needed to measure the dissolved air content before the fluid was loaded into the system. The instrument also needed to measure the dissolved air content in situ and in real time during the de-aeration process. The current methods used to measure the dissolved air content require the fluid to be drawn from the hydraulic system, and additional offline laboratory processing time is involved. During laboratory processing, there is a potential for contamination to occur, especially when subsaturated fluid is to be analyzed. A new method measures the amount of dissolved air in hydraulic fluid through the use of a dissolved oxygen meter. The device measures the dissolved air content through an in situ, real-time process that requires no additional offline laboratory processing time. The method utilizes an instrument that measures the partial pressure of oxygen in the hydraulic fluid. By using a standardized calculation procedure that relates the oxygen partial pressure to the volume of dissolved air in solution, the dissolved air content is estimated. The technique employs luminescent quenching technology to determine the partial pressure of oxygen in the hydraulic fluid. An estimated Henry s law coefficient for oxygen and nitrogen in hydraulic fluid is calculated using a standard method to estimate the solubility of gases in lubricants. The amount of dissolved oxygen in the hydraulic fluid is estimated using the Henry s solubility coefficient and the measured partial pressure of oxygen in solution. The amount of dissolved nitrogen that is in solution is estimated by assuming that the ratio of dissolved nitrogen to dissolved oxygen is equal to the ratio of the gas solubility of nitrogen to oxygen at atmospheric pressure and temperature. The technique was performed at atmospheric pressure and room temperature. The technique could be theoretically carried out at higher pressures and elevated
Intelligent Control of a Novel Hydraulic Forging Manipulator
Directory of Open Access Journals (Sweden)
J. Wang
2011-01-01
Full Text Available The increased demand for large-size forgings has led to developments and innovations of heavy-duty forging manipulators. Besides the huge carrying capacity, some robot features such as force perception, delicacy and flexibility, forging manipulators should also possess. The aim of the work is to develop a heavy-duty forging manipulator with robot features by means of combination of methods in mechanical, hydraulic, and control field. In this paper, through kinematic analysis of a novel forging manipulator, control strategy of the manipulator is proposed considering the function and motion of forging manipulators. Hybrid pressure/position control of hydraulic actuators in forging manipulator is realized. The feasibility of the control method has been verified by the experiments on a real prototype of the novel hydraulic forging manipulator in our institute. The intelligent control of the forging manipulator is performed with programmable logic controller which is suitable for industrial applications.
Creating new life for hydraulic turbines by upgrading and rehabilitation
Energy Technology Data Exchange (ETDEWEB)
Wachter, G.F.
1998-12-01
Methods by which to extend the life of aging hydraulic turbines which are still in operation today are discussed. Upgrading some of these turbines which were built as far back as 80 years ago may be feasible with current rehabilitation technology and advanced computer aided hydraulic mechanical design analysis techniques. The benefits achieved with many hydraulic turbine upgrade and rehabilitation programs include: (1) increased performance, (2) extended service life, (3) stopping accelerated deterioration due to cavitation, (4) reducing detrimental symptoms such as unit vibration, component cracking and excessive wearing ring clearances, (5) reducing the possibility of major failures, and (6) reducing unscheduled forced outages. Increased usage of a non-polluting, renewable energy source is an additional benefit of rehabilitation and upgrading of hydro power generating units.2 refs., 2 tabs., 7 figs.
Concept Design of Movable Beam of Hydraulic Press
Directory of Open Access Journals (Sweden)
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.
Safety estimation of high-pressure hydraulic cylinder using FSI method
Institute of Scientific and Technical Information of China (English)
KIM J.H.; HAN S.M.; KIM Y.J.
2016-01-01
Hydraulic cylinder is a primary component of the hydraulic valve systems.The numerical study of hydraulic cylinder to evaluate the stress analysis,the life assessment and the performance of operation characteristics in hydraulic cylinder were described.The calculation of safety factor,fatigue life,piston chamber pressure,rod chamber pressure and the change of velocity of piston with flow time after the beginning of hydraulic cylinder were incorporated.Numerical analysis was performed using the commercial CFD code,ANSYS with unsteady,dynamic mesh model,two-way FSI (fluid-struc-ture interaction)method and k-εturbulent model.The internal pressure in hydraulic cylinder through stress analysis show higher than those of the yield strength.
Effects of model layer simplification using composite hydraulic properties
Sepulveda, Nicasio; Kuniansky, Eve L.
2010-01-01
The effects of simplifying hydraulic property layering within an unconfined aquifer and the underlying confining unit were assessed. The hydraulic properties of lithologic units within the unconfined aquifer and confining unit were computed by analyzing the aquifer-test data using radial, axisymmetric two-dimensional (2D) flow. Time-varying recharge to the unconfined aquifer and pumping from the confined Upper Floridan aquifer (USA) were simulated using 3D flow. Conceptual flow models were developed by gradually reducing the number of lithologic units in the unconfined aquifer and confining unit by calculating composite hydraulic properties for the simplified lithologic units. Composite hydraulic properties were calculated using either thickness-weighted averages or inverse modeling using regression-based parameter estimation. No significant residuals were simulated when all lithologic units comprising the unconfined aquifer were simulated as one layer. The largest residuals occurred when the unconfined aquifer and confining unit were aggregated into a single layer (quasi-3D), with residuals over 100% for the leakage rates to the confined aquifer and the heads in the confining unit. Residuals increased with contrasts in vertical hydraulic conductivity between the unconfined aquifer and confining unit. Residuals increased when the constant-head boundary at the bottom of the Upper Floridan aquifer was replaced with a no-flow boundary.
Institute of Scientific and Technical Information of China (English)
张晓俊; 权龙; 赵斌
2016-01-01
针对现有液压阀流场(Computational fluid dynamics，CFD)仿真研究中，采用单相流模型进行计算，忽略了流体气化现象对流体密度及其流场的影响，仿真所得相对压力过低与实际不符的问题，运用Fluent软件，采用两相流模型，研究内流式滑阀流场分布，分析阀口开度、流量变化对于阀芯壁面压力分布及其稳态液动力的影响；设计一种壁面压力分布测量的试验方案，测量得到阀芯壁面的压力分布，并通过表面积积分法求出阀芯所受稳态液动力。结果表明：试验所得的内流式滑阀的壁面压力分布及其稳态液动力与仿真结果趋势一致，壁面压力峰值随着阀口开度的增大而减小；阀口开度较小时，稳态液动力的方向为阀口关闭的方向，在阀口开度达到临界点时，稳态液动力的方向为阀口打开的方向；滑阀稳态液动力公式计算由于忽略了入口射流角的变化及其出口处的动量，得到的稳态液动力误差较大，且方向始终指向阀口打开的方向。%In view of the existing problem which does not accord with the fact, that is, in the hydraulic valve flow field CFD study, the single-phase flow model ignores the influence on fluid density and fluid flow field under the condition of cavitation occurred, which leads to the result of the lower relative pressure, by using Fluent software and multiphase model, field distribution is studied on the converged flow sliding valve,and the influence by the change in the flow rate and valve orifice is analyzed on the spool wall pressure distribution and the steady-state flow force. A measurement scheme of wall pressure distribution is designed. The surface integral of the measurement value is the steady flow force. The result is the experimental data is consistent with the simulation’s, and the peak of the wall pressure distribution decreases with the increasing of the orifice area. the orifice area
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
Energy Technology Data Exchange (ETDEWEB)
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.
Demerdash, Omar; Mao, Yuezhi; Liu, Tianyi; Head-Gordon, Martin; Head-Gordon, Teresa
2017-10-01
In this work, we evaluate the accuracy of the classical AMOEBA model for representing many-body interactions, such as polarization, charge transfer, and Pauli repulsion and dispersion, through comparison against an energy decomposition method based on absolutely localized molecular orbitals (ALMO-EDA) for the water trimer and a variety of ion-water systems. When the 2- and 3-body contributions according to the many-body expansion are analyzed for the ion-water trimer systems examined here, the 3-body contributions to Pauli repulsion and dispersion are found to be negligible under ALMO-EDA, thereby supporting the validity of the pairwise-additive approximation in AMOEBA's 14-7 van der Waals term. However AMOEBA shows imperfect cancellation of errors for the missing effects of charge transfer and incorrectness in the distance dependence for polarization when compared with the corresponding ALMO-EDA terms. We trace the larger 2-body followed by 3-body polarization errors to the Thole damping scheme used in AMOEBA, and although the width parameter in Thole damping can be changed to improve agreement with the ALMO-EDA polarization for points about equilibrium, the correct profile of polarization as a function of intermolecular distance cannot be reproduced. The results suggest that there is a need for re-examining the damping and polarization model used in the AMOEBA force field and provide further insights into the formulations of polarizable force fields in general.
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...
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...
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.
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
Phenomenon of methane driven caused by hydraulic fracturing in methane-bearing coal seams
Institute of Scientific and Technical Information of China (English)
Huang Bingxiang; Cheng Qingying; Chen Shuliang
2016-01-01
The methane concentration of the return current will always be enhanced to a certain degree when hydraulic fracturing with bedding drilling is implemented to a gassy coal seam in an underground coal mine. The methane in coal seam is driven out by hydraulic fracturing. Thus, the phenomenon is named as methane driven effect of hydraulic fracturing. After deep-hole hydraulic fracturing at the tunneling face of the gassy coal seam, the coal methane content exhibits a‘low-high-low”distribution along exca-vation direction in the following advancing process, verifying the existence of methane driven caused by hydraulic fracturing in methane-bearing coal seam. Hydraulic fracturing causes the change of pore-water and methane pressure in surrounding coal. The uneven distribution of the pore pressure forms a pore pressure gradient. The free methane migrates from the position of high pore (methane) pressure to the position of low pore (methane) pressure. The methane pressure gradient is the fundamental driving force for methane-driven coal seam hydraulic fracturing. The uneven hydraulic crack propagation and the effect of time (as some processes need time to complete and are not completed instantaneously) will result in uneven methane driven. Therefore, an even hydraulic fracturing technique should be used to avoid the negative effects of methane driven; on the other hand, by taking fully advantage of methane driven, two technologies are presented.
混合式直线力电机的参数计算及有限元分析∗%Parameter Calculation and Finite Element Analysis of Hybrid Linear Force Motor
Institute of Scientific and Technical Information of China (English)
武瑞兵
2015-01-01
Using magnetic circuit analytical method and finite element method electromagnetic motor design parameters and calculate the static characteristic analysis, and the effects of nonlinear magnetic materials on the output of the electromagnetic force;On this basis, the prototype will be manufactured the test results prove that the static force curve of theoretical analysis.%利用磁路解析法和有限元法，对所设计电机进行了电磁参数计算和静特性分析，并研究了导磁材料非线性对输出电磁力的影响。在此基础上，对所制造的样机进行了静态力曲线的测试。试验结果证明了理论分析的正确性。
Quantitative measures for assessment of the hydraulic excavator digging efficiency
Institute of Scientific and Technical Information of China (English)
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.
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...
Institute of Scientific and Technical Information of China (English)
姚峰林; 高世桥
2011-01-01
To calculate the electrostatic force in the micro machined gyroscope is a key problem in the mechanical characteristic of it. Base on the principle of electrostatic drive of the micro machined gyroscope, the paper introduces infinite plane model, edge-effect model and comer-effect model as the electrostatic field computation module of the micro comb. It deduces the formula of capacitance computation and electrostatic force of three models. By the numerical calculation and finite element calculation, it gets the capacitance and the electrostatic force of the gyroscope and the applicable circumstance of each model that the overlap length in variation. It suggests that the edge-effect and the corner-effect of comb should be fully considered when designing and computing the comb.%准确计算静电力是分析微机械陀螺力学特性的关键.文章基于微陀螺静电驱动原理,介绍了微梳齿结构的静电场计算的无限大平板模型,边缘效应模型,拐角效应模型三种模型.推导了三种模型的电容计算公式和静电力计算公式.通过数值计算和有限元计算,得到交叠长度变化时,不同计算模型的电容和静电驱动力的对比和各种模型的适用范围.说明在微尺度条件下静电场的边缘效应和拐角效应应当在设计和计算梳齿时应当充分考虑.
大功率IGBT散热器水冷热阻计算%Forced water cooled thermal-resistance calculation for high-power IGBT radiator
Institute of Scientific and Technical Information of China (English)
罗冰洋; 黄丽婷; 莫易敏; 袁慕
2013-01-01
为了优化水冷散热器散热能力,保障其可靠工作,引用了传热学中的基本原理与公式,以散热器外形的机械尺寸、水的强制对流换热系数和水的导热系数作为参数及变量推导了散热器水冷热阻的计算公式.同时为了满足实际应用,开发了一种专用水冷散热器热阻计算和曲线绘制软件,可以显示热阻随参数变化而变化的各种曲线,也可以直接计算显示热阻值.为散热器的设计中参数的优化选择提供直观方便的参考.%In order to enhance the heat-transfer capability of the water-cooled radiator and ensure its reliability, the basic principle and formula of the heat transfer theory was employed. Taking the radiator dimension, water conductivity and water con-vective heat-transfer coefficient as parameters, the calculation formula of the water cooled thermal resistance of radiator was de-rived. In order to the practical applications of the radiator, a software to draw the curve and calculate the thermal resistance was developed. It can not only display various kinds of curves that thermal resistance changes with the parameters, but also can di-rectly show the calculation result of thermal resistance. With these functions, the parameter optimizing design method which is of good directive significance can be widely used in engineering projects.
Institute of Scientific and Technical Information of China (English)
吴帅; 彭传龙; 焦宗夏; 王晓东; 王晓腾; 彭刚
2014-01-01
Proportional solenoid is the driving devices electromagnetic to control the action of the proportional valve. The overall performance of the proportional solenoid is largely determined by this part. The traditional solenoids have the following disadvantages. The linearity of the solenoid is poor. The effective stroke is short. And the barrier magnetic is installed difficulty. In view of the above the shortcomings, a new structure of the linear force solenoid is presented. The composite magnetic force generated by the permanent magnets and electromagnetic field is using to drive the armature. The barrier magnetic in the new solenoid is canceled, so the solenoid can assemble easily. Theoretical analysis and finite element simulation is done for its design optimization in this paper. One prototype is designed and manufactured, and the designed structure is verified by experiment.%比例电磁铁是控制比例阀先导级阀芯动作的电磁驱动元件，其性能在很大程度上决定比例阀的整体性能。针对传统比例电磁铁线性度差、比例范围短、隔磁环安装困难等不足，设计一种新型结构的比例电磁铁，这种比例电磁铁采用永磁体与线圈产生的复合磁场力驱动衔铁运动，同时新型结构的比例电磁铁中取消传统比例电磁铁的隔磁环结构，降低加工难度并且具有较传统的比例电磁铁更好的性能。对设计的新型电磁铁进行数学建模和理论分析验证其理论的可行性，并且对同等尺寸的比例电磁铁进行仿真优化设计，获得尺寸条件限制下的性能最佳的比例电磁铁设计。在理论分析的基础上，通过对样机的电磁力测试获得的试验数据与理论分析数据一致，验证了这种新型结构的比例电磁铁的实用性。
Varanasi, P.; Sarangi, S.
1974-01-01
Collision-broadened line widths in CO-CO2 and CO-O2 collisions have been calculated by incorporating interactions due to octopoles and hexadecapoles and short-range repulsive interactions into Anderson's (1949) theory. It is shown how these higher-order interactions can be manipulated to yield good agreement with experimental data. A critical evaluation of this totally empirical manipulation suggests that a thorough revision of the theory is required for all but simple dipole-dipole interactions. In the process of the evaluation, the values of the multipole moments are discussed.
Arivazhagan, G; Shanmugam, R; Elangovan, A
2013-03-15
The results of FTIR spectral measurement on equimolar diisopropyl ether-butyric acid binary mixture and quantum chemical calculations on the complex molecule have been presented. Dielectric studies have been carried out on the binary mixture over the entire composition range and at four different temperatures 303 K, 308 K, 313 K and 318 K. n-Butyric acid seems to prefer less polar ether to interact with it. It appears that the usual interpretation of variation of static dielectric constant and positive deviation of excess permittivity from ideal mixture behavior needs to be relooked.
Thermo-hydraulic analysis for sub-module of Chinese HCSB TBM design
Institute of Scientific and Technical Information of China (English)
ZHAO Zhou; FENG Kai-ming; WANG Xiao-yu; YUAN Tao
2006-01-01
Thermo-hydraulic calculation and analysis for sub-module of Chinese HCSB TBM were carried out using FE code ANSYS. Results indicate that temperature distribution in materials used in sub-module is reasonable and acceptable.
The analysis of thermal-hydraulic models in MELCOR code
Energy Technology Data Exchange (ETDEWEB)
Kim, M. H.; Hur, C.; Kim, D. K.; Cho, H. J. [POhang Univ., of Science and TECHnology, Pohang (Korea, Republic of)
1996-07-15
The objective of the present work is to verify the prediction and analysis capability of MELCOR code about the progression of severe accidents in light water reactor and also to evaluate appropriateness of thermal-hydraulic models used in MELCOR code. Comparing the results of experiment and calculation with MELCOR code is carried out to achieve the above objective. Specially, the comparison between the CORA-13 experiment and the MELCOR code calculation was performed.
MA, Z. Y.; Wu, Q. Q.
2016-11-01
A hydraulic-mechanical-electric and structures coupled model of hydropower station system including subsystem models of the penstock, hydro-turbine model, speed governor, synchronous generator as well as grid, rotor-bearing system and powerhouse structure is established. This model is used to simulate the small fluctuation transient process of 10% load-up in the part load condition for hydropower station. Mechanical eccentric force, unbalanced magnetic pull and vortex pressure fluctuation at inlet of draft tube are considered in the numerical calculation. The interaction between hydraulic-mechanical-electric coupled factors and structural vibration properties during the small fluctuation transient process is studied. The results indicate that the speed regulation for turbine has very litter impact on the transient process of generator. In the process of small fluctuation with loading method in this paper, structure of powerhouse is greatly influenced by vortex pressure pulse in the draft tube, and the vibration of unit is excited by loads which caused by itself rotating.
Hydraulic Power Plant Machine Dynamic Diagnosis
Directory of Open Access Journals (Sweden)
Hans Günther Poll
2006-01-01
Full Text Available A method how to perform an entire structural and hydraulic diagnosis of prototype Francis power machines is presented and discussed in this report. Machine diagnosis of Francis units consists on a proper evaluation of acquired mechanical, thermal and hydraulic data obtained in different operating conditions of several rotary and non rotary machine components. Many different physical quantities of a Francis machine such as pressure, strains, vibration related data, water flow, air flow, position of regulating devices and displacements are measured in a synchronized way so that a relation of cause an effect can be developed for each operating condition and help one to understand all phenomena that are involved with such kind of machine. This amount of data needs to be adequately post processed in order to allow correct interpretation of the machine dynamics and finally these data must be compared with the expected calculated data not only to fine tuning the calculation methods but also to accomplish fully understanding of the influence of the water passages on such machines. The way how the power plant owner has to operate its Francis machines, many times also determined by a central dispatcher, has a high influence on the fatigue life time of the machine components. The diagnostic method presented in this report helps one to understand the importance of adequate operation to allow a low maintenance cost for the entire power plant. The method how to acquire these quantities is discussed in details together with the importance of correct sensor balancing, calibration and adequate correlation with the physical quantities. Typical results of the dynamic machine behavior, with adequate interpretation, obtained in recent measurement campaigns of some important hydraulic turbines were presented. The paper highlights the investigation focus of the hydraulic machine behavior and how to tailor the measurement strategy to accomplish all goals. Finally some
Rosas Aguilar, Jorge
2013-05-01
Grain size distribution, porosity, and hydraulic conductivity from over 400 unlithified sediment samples were analized. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly to the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical off sets, were made to produce modified equations that considerably improve the hydraulic conductivity estimates from grain size data for beach, dune, off shore marine, and wadi sediments. Expected hydraulic conductivity estimation errors were reduced. Correction factors were proposed for wadi sediments, taking mud percentage and the standard deviation (in phi units) into account.
Optimisation of Working Areas in Discrete Hydraulic Power Take off-system for Wave Energy Converters
DEFF Research Database (Denmark)
Hansen, Anders Hedegaard; Hansen, Rico Hjerm; Pedersen, Henrik C.
2012-01-01
Fluid power is the leading technology in Power Take Off(PTO) systems in Wave Energy Converters(WEC’s), due to the capability of generating high force at low velocity. However, as hydraulic force controlling system may suffer from large energy losses the efficiency of the hydraulic PTO systems may...... be a limiting factor for wave energy. Therefore, a secondary controlled force system has been proposed as PTO element for WEC’s. This paper investigates the configuration of a multi-chamber cylinder utilising two common pressure lines. By usage of model based optimisation an optimal number and size of working...
Horizontal steam generator PGV-1000 thermal-hydraulic analysis
Energy Technology Data Exchange (ETDEWEB)
Ubra, O. [Skoda Company, Prague (Switzerland); Doubek, M. [Czech Technical Univ., Prague (Switzerland)
1995-12-31
A computer program for the steady state thermal-hydraulic analysis of horizontal steam generator PGV-1000 is presented. The program provides the capability to analyze steam generator PGV-1000 primary side flow and temperature distribution, primary side pressure drops, heat transfer between the primary and secondary sides and multidimensional heat flux distribution. A special attention is paid to the thermal-hydraulics of the secondary side. The code predicts 3-D distribution of the void fraction at the secondary side, mass redistribution under the submerged perforated sheet and the steam generator level profile. By means of developed computer program a detailed thermal-hydraulic study of the PGV-1000 has been carried out. A wide range of calculations has been performed and a set of important steam generator characteristics has been obtained. Some of them are presented in the paper. (orig.). 5 refs.
Theoretical Modeling of Internal Hydraulic Jump in Density Currents
Firoozabadi, Bahar; Aryanfar, Asghar; Afshin, Hossein
2013-01-01
In this paper, we propose an analytical framework for internal hydraulic jumps. Density jumps or internal hydraulic jumps occur when a supper critical flow of water discharges into a stagnant layer of water with slightly different density. The approach used here is control volume method which is also used to analyze ordinary hydraulic jumps. The important difference here is that entrainment is taken into account. Using conservation equations with the aid of some simplifying assumptions we come to an equation that gives jump downstream height as function of jump upstream characteristics and the entrainment. To determine the magnitude of downstream height we use an experimental equation for calculating the entrainment. Finally we verify our framework by comparing the height that we gain from the derived equation with some experimental data.
RESEARCH ON THE ENERGY ECONOMIZATION OF ELECTRO-HYDRAULIC HAMMER
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
郭春秋; 解家春; 刘兴民
2013-01-01
在研究堆内进行辐照在线产氚试验是ITER计划专项国内配套研究项目之一.本工作主要针对研究堆内辐照氦冷陶瓷氚增殖剂包层(简称陶瓷)球床组件的试验技术要求,评估辐照陶瓷球床组件设计方案的可行性.通过对不同的陶瓷球床组件结构参数和组件在堆内的不同辐照位置,进行热工流体力学设计计算,得到满足要求的入堆辐照陶瓷球床组件设计方案.%In-pile irradiation & in-situ tritium extraction experiment is one of associated domestic research projects in ITER special program.According to the technical requirements of in-pile irradiation experiment of helium cooled ceramic breeder (ceramic) pebble bed assembly in a research reactor,the feasibility of the design for the in-pile irradiation & in-situ tritium extraction experiment of ceramic pebble bed assembly was evaluated.By conducting thermal-hydraulic design calculation with different in-pile irradiation channels,locations and structure parameters for ceramic pebble bed assembly,a reasonable design scheme of ceramic pebble bed assembly satisfying the design requirements for in-pile irradiation was obtained.
Measurement and modeling of unsaturated hydraulic conductivity: Chapter 21
Perkins, Kim S.; Elango, Lakshmanan
2011-01-01
The unsaturated zone plays an extremely important hydrologic role that influences water quality and quantity, ecosystem function and health, the connection between atmospheric and terrestrial processes, nutrient cycling, soil development, and natural hazards such as flooding and landslides. Unsaturated hydraulic conductivity is one of the main properties considered to govern flow; however it is very difficult to measure accurately. Knowledge of the highly nonlinear relationship between unsaturated hydraulic conductivity (K) and volumetric water content () is required for widely-used models of water flow and solute transport processes in the unsaturated zone. Measurement of unsaturated hydraulic conductivity of sediments is costly and time consuming, therefore use of models that estimate this property from more easily measured bulk-physical properties is common. In hydrologic studies, calculations based on property-transfer models informed by hydraulic property databases are often used in lieu of measured data from the site of interest. Reliance on database-informed predicted values with the use of neural networks has become increasingly common. Hydraulic properties predicted using databases may be adequate in some applications, but not others.
Interaction of hydraulic and buckling mechanisms in blowout fractures.
Nagasao, Tomohisa; Miyamoto, Junpei; Jiang, Hua; Tamaki, Tamotsu; Kaneko, Tsuyoshi
2010-04-01
The etiology of blowout fractures is generally attributed to 2 mechanisms--increase in the pressure of the orbital contents (the hydraulic mechanism) and direct transmission of impacts on the orbital walls (the buckling mechanism). The present study aims to elucidate whether or not an interaction exists between these 2 mechanisms. We performed a simulation experiment using 10 Computer-Aided-Design skull models. We applied destructive energy to the orbits of the 10 models in 3 different ways. First, to simulate pure hydraulic mechanism, energy was applied solely on the internal walls of the orbit. Second, to simulate pure buckling mechanism, energy was applied solely on the inferior rim of the orbit. Third, to simulate the combined effect of the hydraulic and buckling mechanisms, energy was applied both on the internal wall of the orbit and inferior rim of the orbit. After applying the energy, we calculated the areas of the regions where fracture occurred in the models. Thereafter, we compared the areas among the 3 energy application patterns. When the hydraulic and buckling mechanisms work simultaneously, fracture occurs on wider areas of the orbital walls than when each of these mechanisms works separately. The hydraulic and buckling mechanisms interact, enhancing each other's effect. This information should be taken into consideration when we examine patients in whom blowout fracture is suspected.
Effects of model layer simplification using composite hydraulic properties
Kuniansky, Eve L.; Sepulveda, Nicasio; Elango, Lakshmanan
2011-01-01
Groundwater provides much of the fresh drinking water to more than 1.5 billion people in the world (Clarke et al., 1996) and in the United States more that 50 percent of citizens rely on groundwater for drinking water (Solley et al., 1998). As aquifer systems are developed for water supply, the hydrologic system is changed. Water pumped from the aquifer system initially can come from some combination of inducing more recharge, water permanently removed from storage, and decreased groundwater discharge. Once a new equilibrium is achieved, all of the pumpage must come from induced recharge and decreased discharge (Alley et al., 1999). Further development of groundwater resources may result in reductions of surface water runoff and base flows. Competing demands for groundwater resources require good management. Adequate data to characterize the aquifers and confining units of the system, like hydrologic boundaries, groundwater levels, streamflow, and groundwater pumping and climatic data for recharge estimation are to be collected in order to quantify the effects of groundwater withdrawals on wetlands, streams, and lakes. Once collected, three-dimensional (3D) groundwater flow models can be developed and calibrated and used as a tool for groundwater management. The main hydraulic parameters that comprise a regional or subregional model of an aquifer system are the hydraulic conductivity and storage properties of the aquifers and confining units (hydrogeologic units) that confine the system. Many 3D groundwater flow models used to help assess groundwater/surface-water interactions require calculating ?effective? or composite hydraulic properties of multilayered lithologic units within a hydrogeologic unit. The calculation of composite hydraulic properties stems from the need to characterize groundwater flow using coarse model layering in order to reduce simulation times while still representing the flow through the system accurately. The accuracy of flow models with
Johnson, Daniel M; Wortemann, Remi; McCulloh, Katherine A; Jordan-Meille, Lionel; Ward, Eric; Warren, Jeffrey M; Palmroth, Sari; Domec, Jean-Christophe
2016-08-01
Water transport from soils to the atmosphere is critical for plant growth and survival. However, we have a limited understanding about many portions of the whole-tree hydraulic pathway, because the vast majority of published information is on terminal branches. Our understanding of mature tree trunk hydraulic physiology, in particular, is limited. The hydraulic vulnerability segmentation hypothesis (HVSH) stipulates that distal portions of the plant (leaves, branches and roots) should be more vulnerable to embolism than trunks, which are nonredundant organs that require a massive carbon investment. In the current study, we compared vulnerability to loss of hydraulic function, leaf and xylem water potentials and the resulting hydraulic safety margins (in relation to the water potential causing 50% loss of hydraulic conductivity) in leaves, branches, trunks and roots of four angiosperms and four conifer tree species. Across all species, our results supported strongly the HVSH as leaves and roots were less resistant to embolism than branches or trunks. However, branches were consistently more resistant to embolism than any other portion of the plant, including trunks. Also, calculated whole-tree vulnerability to hydraulic dysfunction was much greater than vulnerability in branches. This was due to hydraulic dysfunction in roots and leaves at less negative water potentials than those causing branch or trunk dysfunction. Leaves and roots had narrow or negative hydraulic safety margins, but trunks and branches maintained positive safety margins. By using branch-based hydraulic information as a proxy for entire plants, much research has potentially overestimated embolism resistance, and possibly drought tolerance, for many species. This study highlights the necessity to reconsider past conclusions made about plant resistance to drought based on branch xylem only. This study also highlights the necessity for more research of whole-plant hydraulic physiology to better
Institute of Scientific and Technical Information of China (English)
张爽; 邹建华
2015-01-01
简要介绍了大型电机螺纹连接的基本类型，并结合实例详细介绍了螺纹连接的拧紧力矩及预紧力计算过程，对计算值进行了现场验证，以便在电机设计、制造以及用户对电机现场安装、维护维修时，给出准确的螺纹拧紧力矩和预紧力值，为电机设计人员提供参考。%Fundamental type of threaded connection of large motor is briefly introduced in this paper, combined with examples calculation process of tightening torque and pretightening force of threaded connection are introduced, and calculated value is verified onsite, so as to give accurate threaded tightening torque and pretightening force for designing, manufacturing on-site installation and maintaining of the motor. Reference for the motor designer is also provided.
Institute of Scientific and Technical Information of China (English)
刘宝权; 张鸿; 王自东; 王军生; 张岩
2011-01-01
对冷轧带钢轧制过程中因辊缝倾斜调整过量所导致的单边浪缺陷和断带进行了分析,应用影响函数法计算辊系变形,通过迭代计算出附加倾斜后的传动侧轧制力、操作侧轧制力、辊间压力分布、单位宽度轧制力分布、出口厚度横向分布、出口横向张应力分布。理论计算和实际测量结果表明,冷轧机双侧轧制力差值与倾斜调整量呈近似线性增长的规律。根据轧制力差值与倾斜量之间的比例关系,用实测轧制力差值对倾斜值进行动态限幅,可有效避免冷轧过程中断带事故的发生。%The single edge wave and strip break caused by excessive tilting adjustment were analyzed. Influence func tion method was adopted to model the roll deformation. Adding different tilt, roll force of drive side, roll force of operator side, transverse distribution of contact pressure between rolls, transverse distribution of roll force, trans verse distribution of strip thickness at exit side and transverse distribution of tension at exit side were calculated by using iterative method. The theoretical calculation and the actual measurement results show that the difference be- tween the bilateral increases almost linearly with tilt adjustment value. The break strip accidents are effectively aver ted by dynamic limiting to tilt setting value with the measured differential roll force, according to the proportional relationship between the differential roll force and the tilt.
Kattawar, G. W.
1980-01-01
The multipole expansion obtained by Morita et al. (1968) of the Gaussian laser beam used to levitate an aerosol particle in order that its complete phase matrix may be measured is compared with that of Tsai and Pogorzelski (1975) in order to demonstrate the effect of the incorrect expansion used by Morita. Errors incurred by the use of an equation in which one side satisfies the scalar wave equation while the other side does not and can be reduced to a plane wave amplitude are calculated as functions of the inverse of the wave number times the beam waist, the wave number times the radial spherical coordinate and the angular spherical coordinate. Errors on the order of a few percent, considered undetectable are obtained in the squared-field amplitudes due to the expansion, however, they are found to become significant (several tens of percent) when the angle is zero. It is concluded that the expansion of Morita should only be used in the regions where the spherical angle is less than 0.01 and its product with the wave number and the radial spherical coordinate is less than unity.
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
Directory of Open Access Journals (Sweden)
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.
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.
Fundamental characteristics of oil hydraulic servo system; Yuatsu servo kei no kihonteki tokusei
Energy Technology Data Exchange (ETDEWEB)
Suzuki, K. [Musashi Instsitute of Technology, Tokyo (Japan)
1999-05-15
Since a hydraulic servo generates a great force very quickly upon receiving a small force or electric power, it is widely used in machine tools, construction machinery, and vehicles. The basics are that a high pressure fluid generated by a hydraulic pump is controlled by a valve and forwarded to a hydraulic cylinder or rotary hydraulic motor for the generation of a parallel motion or rotation. For the control of the valve, there are the mechanical-hydraulic servo mechanism in which the valve is operated by mechanical linkage and the electrical-hydraulic servo system in which the valve is driven by electric signals. It is difficult to perform sophisticated control such as optimum control by use of the mechanical method while the electrical method may be applied to such sophisticated control. In the former, a hydraulic servo system is constructed using mechanical feedback. It is simpler and more reliable than the other, and is used for the control of aircraft wings and for the steering of ships and vehicles. Using the latter, electric signals low in power are amplified in a servo amplifier before being sent to the servo valve. For the driving of the spool in a servo valve, the nozzle and flapper system is widely in use. (NEDO)
Time domain responses of hydraulic bushing with two flow passages
Chai, Tan; Dreyer, Jason T.; Singh, Rajendra
2014-02-01
Hydraulic bushings are commonly employed in vehicle suspension and body sub-frame systems to control motion, vibration, and structure-borne noise. Since literature on this topic is sparse, a controlled bushing prototype which accommodates a combination of long and short flow passages and flow restriction elements is first designed, constructed and instrumented. Step-up and step-down responses of several typical fluid-filled bushing configurations are measured along with steady harmonic time histories of transmitted force and internal pressures. To analyze the experimental results and gain physical insights into the hydraulic bushing system, lumped system models of bushings with different design features are developed, and analytical expressions of transmitted force and internal pressure responses are derived by using the convolution method. Parametric studies are also conducted to examine the effect of hydraulic element parameters. System parameters are successfully estimated for both harmonic and step responses using theory and measurements, and the dynamic force measurements are analyzed using analytical predictions. Finally, some nonlinearities of the system are also observed, and the fluid resistance of flow passage is found to be the most nonlinear element.
Rustad, James R.; Rosso, Kevin M.; Felmy, Andrew R.
2004-04-01
We present a molecular model for ferrous-ferric electron transfer in an aqueous solution that accounts for electronic polarizability and exhibits spontaneous cation hydrolysis. An extended Lagrangian technique is introduced for carrying out calculations of electron-transfer barriers in polarizable systems. The model predicts that the diabatic barrier to electron transfer increases with increasing pH, due to stabilization of the Fe3+ by fluctuations in the number of hydroxide ions in its first coordination sphere, in much the same way as the barrier would increase with increasing dielectric constant in the Marcus theory. We have also calculated the effect of pH on the potential of mean force between two hydrolyzing ions in aqueous solution. As expected, increasing pH reduces the potential of mean force between the ferrous and ferric ions in the model system. The magnitudes of the predicted increase in diabatic transfer barrier and the predicted decrease in the potential of mean force nearly cancel each other at the canonical transfer distance of 0.55 nm. Even though hydrolysis is allowed in our calculations, the distribution of reorganization energies has only one maximum and is Gaussian to an excellent approximation, giving a harmonic free energy surface in the reorganization energy F(ΔE) with a single minimum. There is thus a surprising amount of overlap in electron-transfer reorganization energies for Fe2+-Fe(H2O)63+, Fe2+-Fe(OH)(H2O)52+, and Fe2+-Fe(OH)2(H2O)+ couples, indicating that fluctuations in hydrolysis state can be viewed on a continuum with other solvent contributions to the reorganization energy. There appears to be little justification for thinking of the transfer rate as arising from the contributions of different hydrolysis states. Electronic structure calculations indicate that Fe(H2O)62+-Fe(OH)n(H2O)6-n(3-n)+ complexes interacting through H3O2- bridges do not have large electronic couplings.
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
Directory of Open Access Journals (Sweden)
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.
Mitra, Devrani; Pelmenschikov, Vladimir; Guo, Yisong; Case, David A; Wang, Hongxin; Dong, Weibing; Tan, Ming-Liang; Ichiye, Toshiko; Jenney, Francis E; Adams, Michael W W; Yoda, Yoshitaka; Zhao, Jiyong; Cramer, Stephen P
2011-06-14
We have used (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to study oxidized and reduced forms of the [4Fe-4S] cluster in the D14C variant ferredoxin from Pyrococcus furiosus (Pf D14C Fd). To assist the normal-mode assignments, we conducted NRVS with D14C ferredoxin samples with (36)S substituted into the [4Fe-4S] cluster bridging sulfide positions, and a model compound without ligand side chains, (Ph(4)P)(2)[Fe(4)S(4)Cl(4)]. Several distinct regions of NRVS intensity are identified, ranging from "protein" and torsional modes below 100 cm(-1), through bending and breathing modes near 150 cm(-1), to strong bands from Fe-S stretching modes between 250 and ∼400 cm(-1). The oxidized ferredoxin samples were also investigated by resonance Raman (RR) spectroscopy. We found good agreement between NRVS and RR frequencies, but because of different selection rules, the intensities vary dramatically between the two types of spectra. The (57)Fe partial vibrational densities of states for the oxidized samples were interpreted by normal-mode analysis with optimization of Urey-Bradley force fields for local models of the [4Fe-4S] clusters. Full protein model calculations were also conducted using a supplemented CHARMM force field, and these calculations revealed low-frequency modes that may be relevant to electron transfer with Pf Fd partners. Density functional theory (DFT) calculations complemented these empirical analyses, and DFT was used to estimate the reorganization energy associated with the [Fe(4)S(4)](2+/+) redox cycle. Overall, the NRVS technique demonstrates great promise for the observation and quantitative interpretation of the dynamical properties of Fe-S proteins.
Mitra, Devrani; Pelmenschikov, Vladimir; Guo, Yisong; Case, David A.; Wang, Hongxin; Dong, Weibing; Tan, Ming-Liang; Ichiye, Toshiko; Jenney, Francis E.; Adams, Michael W. W.; Yoda, Yoshitaka; Zhao, Jiyong; Cramer, Stephen P.
2011-01-01
We have used 57Fe nuclear resonance vibrational spectroscopy (NRVS) to study oxidized and reduced forms of the [4Fe-4S] cluster in the D14C variant ferredoxin from Pyrococcus furiosus (Pf D14C Fd). To assist the normal mode assignments, we recorded the NRVS of D14C ferredoxin samples with 36S substituted into the [4Fe-4S] cluster bridging sulfide positions, and a model compound without ligand side chains: (Ph4P)2[Fe4S4Cl4]. Several distinct regions of NRVS intensity are identified, ranging from `protein' and torsional modes below 100 cm−1, through bending and breathing modes near 150 cm−1, to strong bands from Fe-S stretching modes between 250 cm−1 and ~400 cm−1. The oxidized ferredoxin samples were also investigated by resonance Raman (RR) spectroscopy. We found good agreement between NRVS and RR frequencies, but because of different selection rules, the intensities vary dramatically between the two types of spectra. The 57Fe partial vibrational densities of states (PVDOS) for the oxidized samples were interpreted by normal mode analysis with optimization of Urey-Bradley force fields for local models of the [4Fe-4S] clusters. Full protein model calculations were also conducted using a supplemented CHARMM force field, and these calculations revealed low frequency modes that may be relevant to electron transfer with Pf Fd partners. Density functional theory (DFT) calculations complemented these empirical analyses, and DFT was used to estimate the reorganization energy associated with the [Fe4S4]2+/1+ redox cycle. Overall, the NRVS technique demonstrates great promise for the observation and quantitative interpretation of the dynamical properties of Fe-S proteins. PMID:21500788
USE OF GEOSYNTHETIC CASINGS IN HYDRAULIC ENGINEERING
Directory of Open Access Journals (Sweden)
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.
基于机械系统运动学的滑阀泵滑阀杆不平衡力的计算%Modeling and Calculation of Rod’s Inertia Force in Rotary Piston Vacuum Pump
Institute of Scientific and Technical Information of China (English)
于振华; 姜康
2016-01-01
The large inertial force,exerted on the sliding-valve rod intheeccentric motion of thetwo-stage rota-rypiston vacuum pump (Model 2H-1 50),was mathematically modeled and theoretically calculated on the basis of kinematics and dynamics of rigid mechanical system.The motivation was to design an effective counterweight to dampen the inertia force induced vibration.The calculated results show that the time-dependent inertial force is non-harmonic and its magnitude and direction are changing instantaneously and sharply in one cycle.Based on the calculation,the counterweight was optimized and fixed at the proper position in the prototyped rotary piston pump. The test results show that the counterweight significantly dampened the vibration by reducing the inertia force and displacement of the rotary piston vacuum pump.We suggest that the calculation of the inertial force may be of much technological interest in dampening the vibration of rotary piston vacuum pump.%滑阀式真空泵的运动属于偏心运动，该泵的滑阀构件在工作中产生的不平衡惯性力引起泵的较大振动，但是长期以来无精确的计算滑阀不平衡惯性力的方法，因此确定滑阀的不平衡惯性力幅值成为降低滑阀泵振动的关键所在。本文运用机械系统运动学理论推导了精确计算滑阀杆的不平衡惯性力的公式，计算了2H-150型双级滑阀真空泵滑阀杆在一个工作周期内的不平衡惯性力。计算获得了滑阀杆不平衡力幅值的精确值，计算结果表明，滑阀杆的大小和方向是不断发生变化的，引起的振动是非简谐振动。根据滑阀杆不平衡惯性力的计算结果进行动平衡配重，配重后的滑阀泵振动力和振动位移大幅度下降。结果表明该方法正确可靠，为滑阀泵减振分析提供了准确数据。
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
Hydraulic fracturing system and method
Energy Technology Data Exchange (ETDEWEB)
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.
DEFF Research Database (Denmark)
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
Directory of Open Access Journals (Sweden)
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.
Implementation and implications of macrophyte reconfiguration in hydraulic river modeling
Verschoren, Veerle; Schoelynck, Jonas; Buis, Kerst; Meire, Dieter; Bal, Kris; Meire, Patrick; Temmerman, Stijn
2014-05-01
In lowland rivers, abundant macrophyte growth can often be observed. The aquatic vegetation has an impact on the flow by creating friction which results in increased water levels and decreased flow velocities. At the same time submerged macrophytes are susceptible to hydrodynamic forces of the water. Their morphology is therefore often flexible and streamlined so that it enables reconfiguration (i.e. bending of macrophytes with water flow) and decreases potential damage at high flow velocities. Knowledge of these mutual interactions is crucial in order to model water flow in vegetated rivers. A correct estimation of flow velocity and water height is indispensable for the calculation of hydraulic, ecological and geomorphological parameters. The total resistance to water flow in a river can be described by a Manning coefficient. This value is influenced by river characteristics as well as by the presence of macrophytes. In this study a simple method is developed to quantify the resistance created by macrophytes after reconfiguration of their canopy. In order to achieve this we derive model formulations and plant parameters for three different macrophyte species and compare model simulation with measured flow velocity data for two case studies. Furthermore, the effect of macrophyte reconfiguration is investigated by modeling the same case studies with and without the implementation of macrophyte reconfiguration. It was found that the local resistance created by the vegetation was overestimated when reconfiguration was not considered. This resulted in an overestimation of stream velocity adjacent to the vegetation and an underestimation of the stream velocity within and behind the vegetation. Another effect was a higher water level gradient and consequently a higher Manning coefficient in the scenario without reconfiguration compared to the scenario with reconfiguration. Reconfiguration had also an influence on ecological and geomorphological parameters. It was found
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.
远洋船用伸缩折叠起重机液压系统设计%Marine telescopic folding crane hydraulic system design
Institute of Scientific and Technical Information of China (English)
卢志珍; 倪学虎; 舒希勇; 王成龙
2012-01-01
在分析伸缩折叠起重机对液压系统要求的基础上,针对起重机技术参数及客户要求提出了液压系统设计的思路.对关键液压元件——液压泵、液压马达、液压缸进行了计算选型,设计了液压原理图,并阐述了起重机液压回路的工作原理.%Based on the analysis of telescopic folding crane hydraulic system requirements,put forward the hydraulic system design thinking according to crane technical parameters and requirements of customers. Calculation and type selection of the key hydraulic components------hydraulic pump and hydraulic motor, hydraulic cylinder, design hydraulic principle diagram and expoundscrane hydraulic loop principle of work.
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
Climbing robot actuated by meso-hydraulic artificial muscles
Bryant, Matthew; Fitzgerald, Jason; Miller, Samuel; Saltzman, Jonah; Kim, Sangkyu; Lin, Yong; Garcia, Ephrahim
2014-03-01
This paper presents the design, construction, experimental characterization, and system testing of a legged, wall-climbing robot actuated by meso-scale hydraulic artificial muscles. While small wall-climbing robots have seen increased research attention in recent years, most authors have primarily focused on designs for the gripping and adhesion of the robot to the wall, while using only standard DC servo-motors for actuation. This project seeks to explore and demonstrate a different actuation mechanism that utilizes hydraulic artificial muscles. A four-limb climbing robot platform that includes a full closed-loop hydraulic power and control system, custom hydraulic artificial muscles for actuation, an on-board microcontroller and RF receiver for control, and compliant claws with integrated sensing for gripping a variety of wall surfaces has been constructed and is currently being tested to investigate this actuation method. On-board power consumption data-logging during climbing operation, analysis of the robot kinematics and climbing behavior, and artificial muscle force-displacement characterization are presented to investigate and this actuation method.
HYDRAULIC DEVICES FOR HYDROSYSTEM TAILRACE PROTECTION
Directory of Open Access Journals (Sweden)
Kuznetsova Y. A.
2015-11-01
Full Text Available Based on the Karman vortex theory, the calculated dependences for velocity induced by profile action in the flow, lifting force and drag force, acting on the profile, are determined. Calculations, performed in MathCAD, allowed, for the given up-stream velocity, to calculate height of mid-section of the bed-formation profile, width of the profile along the chord, span of the profile, angle of attack, velocity of the induced flow. For the calculated profile parameters, the velocity circulation value, drag force and lifting force are determined. As the bed-formation profiles, it is recommended to use flat plates, frame constructions with transverse ribs in the form of arch, fish-like symmetric or slightly curved profiles. Ways of the profile installation in the flow, depending on the angle of attack, are evaluated: three versions - for symmetric profiles, and six versions - for asymmetric profiles. Diagram of the device for the hydrosystem tailrace protection against erosion is developed on the basis of submerged NACA 0302 profile or profile of Zhukovsky, made of flexible materials, including profiles, system of supporting and regulating ropes, and shore or bottom supports. This design is mobile, intended for the periodic regulation of sediment yield
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...
Control Reconfigurability of Bilinear Hydraulic Drive Systems
DEFF Research Database (Denmark)
Shaker, Hamid Reza; Tahavori, Maryamsadat
2011-01-01
be effective if sufficient redundancy does not exist in the process. A measure for control reconfigurability which reveals the level of redundancy in connection with feedback control is proposed in this paper for bilinear systems. The proposed control reconfigurability measure is the extension of its gramian......The objective of the methods within the framework of the plug and play process control and particularly fault tolerant control is to establish control techniques which guarantee a certain performance through control reconfiguration at the occurrence of the faults or changes. These methods cannot......-based analogous counterpart, which has been previously proposed for the linear processes. The control reconfigurability is calculated for the bilinear models of an electro-hydraulic drive to show its relevance to redundant actuating capabilities in the models....
Hydraulic fracture design and optimization of gas storage wells
Energy Technology Data Exchange (ETDEWEB)
Mohaghegh, S.; Ameri, S. [Petroleum and Natural Gas and Engineering Department, West Virginia University, P.O. Box 6070, Morgantown, WV (United States); Balanb, B. [Schlumberger Austin Product Center, 8311 North FM 620 Road, Austin, TX (United States); Platon, V. [Baker Atlas, 10201 Westheimer Rd., Houston, TX (United States)
1999-10-01
Conventional hydraulic fracture design and optimization involves the use of two- or three-dimensional hydraulic fracture simulators. These simulators need a wealth of reservoir data as input to provide users with usable results. In many cases, such data are not available or very expensive to acquire. This paper provides a new methodology that can be used in cases where detail reservoir data are not available or prohibitively expensive to acquire. Through the use of two virtual intelligence techniques, namely neural networks and genetic algorithms, hydraulic fracture treatments are designed using only the available data. The unique design optimization method presented here is a logical continuation of the study that was presented in two previous papers [McVey et al., 1996, Identification of parameters influencing the response of gas storage wells to hydraulic fracturing with the aid of a neural network, SPE Computer Applications Journal, Apr., 54-57; Mohaghegh et al., 1996b, Predicting well stimulation results in a gas storage field in the absence of reservoir data, using neural networks, SPE Reservoir Engineering Journal, Nov., 54-57]. A quick review of these papers is included here. This method will use the available data on each well, which includes basic well information, production history and results of previous frac job treatments, and provides engineer with a detail optimum hydraulic fracture design unique to each well. The expected post-hydraulic fracture deliverability for the designed treatment is also provided to assist engineers in estimating incremental increase in recovery to be used in economic calculations. There are no simulated data throughout this study and all data used for development and verification of all methods are actual field data.
Institute of Scientific and Technical Information of China (English)
强新伟; 武良臣; 李建华; 牛永生
2001-01-01
本文通过对三种不同压力分布(弹流润滑理论、赫兹理论、平均赫兹理论)下牵引力的MATLAB编程计算，探讨了赫兹理论、平均赫兹理论的精确程度，以及其各自的适用范围。%: In this paper, through the programming calculation of traction force with MATLAB in three different pressure distribution (EHL theory、 HZ theory、 MP theory), we discuss the precision degree of both HZ theory and MP theory, and their applying field respectively.
Rosas, Jorge
2014-07-19
Grain size distribution, porosity, and hydraulic conductivity were determined for 39 sediment samples collected from ephemeral streams (wadis) in western Saudi Arabia. The measured hydraulic conductivity values were then compared to values calculated using 20 different empirical equations commonly used to estimate hydraulic conductivity from grain size analyses. It was found that most of the hydraulic conductivity values estimated from the empirical equations correlated very poorly with the measured hydraulic conductivity values. Modifications of the empirical equations, including changes to special coefficients and statistical offsets, were made to produce modified equations that considerably improved the hydraulic conductivity estimates from grain size data for wadi sediments. The Chapuis, Hazen, Kozeny, Slichter, Terzaghi, and Barr equations produced the best correlations, but still had relatively high predictive errors. The Chapius equation was modified for wadi sediments by incorporating mud percentage and the standard deviation (in phi units) into a new equation that reduced the predicted hydraulic conductivity error to ±14.1 m/day. The equation is best applied to ephemeral stream samples that have hydraulic conductive values greater than 2 m/day.
Institute of Scientific and Technical Information of China (English)
毛伙南
2012-01-01
The survey of unit type curtain wall is researched. Using the ANSYS software, the internal force and displacement of the unit type plate structure which are composed of the trough type aluminum plate and S stiffening ribs (portal type frame) are calculated. The stiffening rib and the aluminum plate corner partial rivet loosens by the rigid joint turns the hinge point is studied. The computation model is built and its biggest internal force and displacement are obtained. Finally, the practical application is in troduced.%阐述了槽型铝板和加劲肋构成的单元式幕墙的内力及变形计算.采用ANSYS软件对单元板块由槽型铝板与5条加劲肋组成的结构的内力和变形进行计算,研究了加劲肋转角处由于局部铆钉松脱由刚结点变成铰接点后其计算模型发生改变的应力及位移计算,最后介绍实际应用.
Thermal-hydraulic modeling of reactivity accidents in MTR reactors
Directory of Open Access Journals (Sweden)
Khater Hany
2006-01-01
Full Text Available This paper describes the development of a dynamic model for the thermal-hydraulic analysis of MTR research reactors during a reactivity insertion accident. The model is formulated for coupling reactor kinetics with feedback reactivity and reactor core thermal-hydraulics. To represent the reactor core, two types of channels are considered, average and hot channels. The developed computer program is compiled and executed on a personal computer, using the FORTRAN language. The model is validated by safety-related benchmark calculations for MTR-TYPE reactors of IAEA 10 MW generic reactor for both slow and fast reactivity insertion transients. A good agreement is shown between the present model and the benchmark calculations. Then, the model is used for simulating the uncontrolled withdrawal of a control rod of an ETRR-2 reactor in transient with over power scram trip. The model results for ETRR-2 are analyzed and discussed.
Hydraulic modelling of drinking water treatment plant operations
Directory of Open Access Journals (Sweden)
L. C. Rietveld
2009-06-01
Full Text Available The flow through a unit of a drinking water treatment plant is one of the most important parameters in terms of a unit's effectiveness. In the present paper, a new EPAnet library is presented with the typical hydraulic elements for drinking water treatment processes well abstraction, rapid sand filtration and cascade and tower aeration. Using this treatment step library, a hydraulic model was set up, calibrated and validated for the drinking water treatment plant Harderbroek. With the actual valve position and pump speeds, the flows were calculated through the several treatment steps. A case shows the use of the model to calculate the new setpoints for the current frequency converters of the effluent pumps during a filter backwash.
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.
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.
Hydrodynamic Forces on Reverse Tainter Valves; Hydraulic Model Investigation
2013-12-01
FACILITY: Completion of a physical model study of the culvert valves of the Eisenhower and Snell Locks, St. Lawrence Seaway (Stockstill et al., in...evaluation of culvert valves at Eisenhower and Snell Locks, St. Lawrence Seaway. Vicksburg, MS: US Army Engineer Research and Development Center
Calculations to an IAHR-benchmark test using the CFD-code CFX-4
Energy Technology Data Exchange (ETDEWEB)
Krepper, E.
1998-10-01
The calculation concerns a test, which was defined as a benchmark for 3-D codes by the working group of advanced nuclear reactor types of IAHR (International Association of Hydraulic Research). The test is well documented and detailed measuring results are available. The test aims at the investigation of phenomena, which are important for heat removal at natural circulation conditions in a nuclear reactor. The task for the calculation was the modelling of the forced flow field of a single phase incompressible fluid with consideration of heat transfer and influence of gravity. These phenomena are typical also for other industrial processes. The importance of correct modelling of these phenomena also for other applications is a motivation for performing these calculations. (orig.)
Hydraulic resistance of a plant root to water-uptake: A slender-body theory.
Chen, Kang Ping
2016-05-07
A slender-body theory for calculating the hydraulic resistance of a single plant root is developed. The work provides an in-depth discussion on the procedure and the assumptions involved in calculating a root׳s internal hydraulic resistance as well as the physical and the mathematical aspects of the external three-dimensional flow around the tip of a root in a saturated soil and how this flow pattern enhances uptake and reduces hydraulic resistance. Analytical solutions for the flux density distribution on the stele-cortex interface, local water-uptake profile inside the stele core, the overall water-uptake at the base of the stele, and the total hydraulic resistance of a root are obtained in the slender-body limit. It is shown that a key parameter controlling a root's hydraulic resistance is the dimensionless axial conductivity in the stele, which depends on the permeabilities of the stele and the cortex as well as the root's radial and axial dimensions. Three-dimensional tip effect reduces a root's hydraulic resistance by as much as 36% when compared to the radial flow theory of Landsberg and Fowkes. In addition, the total hydraulic resistance cannot be generally decomposed into the direct sum of a radial resistance and an axial resistance.
Estimation of hydraulic parameters in a complex porous aquifer system using geoelectrical methods.
Kazakis, N; Vargemezis, G; Voudouris, K S
2016-04-15
Geoelectrical methods have been widely used for the estimation of aquifer hydraulic properties. In this study, geoelectrical methods were applied in a lithologically and hydrochemically complex porous aquifer to estimate its porosity, hydraulic conductivity and transmissivity. For this purpose, the electrical resistivity of the aquifer as well as the electrical conductivity of the groundwater was measured in 37 sites and wells. Initially, the Archie's law was used to generate sets of cementation factor (m) and alpha (α) parameter from which the mode values of α=0.98 and m=1.75 are representative of the studied aquifer. The transmissivity of the aquifer varies from 5.1×10(-3) to 3.1×10(-5)m(2)/s, whereas the mean value of its porosity is 0.45. The hydraulic conductivity of the aquifer which was calculated according to Archie's law varies from 2.08×10(-6) to 6.84×10(-5)m/s and is strongly correlated with the pumping test's hydraulic conductivity. In contrast, the hydraulic conductivity which was calculated using Dar-Zarrouk parameters presents lower correlation with the pumping test's hydraulic conductivity. Furthermore, a relation between aquifer resistivity and hydraulic conductivity was established for the studied aquifer to enable the estimation of these parameters in sites lacking data.
RESEARCH ON STABILITY AND MINIMUM ORIFICE AREA OF HYDRAULIC SERVO POSITION CONTROL SYSTEM
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper reports results of research on the stability of a hydraulic servo position system using generalization pulse code modulation (GPCM) and common on/off valves for hydraulic servo control. The de- scribing function was first used to analyze the system′s stability, and based on the nonlinear theory, an equation calculating the minimum orifice area of GPCM valves was derived by applying results of analysis on the stability of the GPCM control system. In the end, aimed at developing a hydraulic servo position system to be used in a paint robot, simulation and experiment were carried out. The results show that the theoretical conclusions accorded with practical results.
Advanced geothermal hydraulics model -- Phase 1 final report, Part 2
Energy Technology Data Exchange (ETDEWEB)
W. Zheng; J. Fu; W. C. Maurer
1999-07-01
An advanced geothermal well hydraulics model (GEODRIL) is being developed to accurately calculate bottom-hole conditions in these hot wells. In Phase 1, real-time monitoring and other improvements were added to GEODRIL. In Phase 2, GEODRIL will be integrated into Marconi's Intelligent Drilling Monitor (IDM) that will use artificial intelligence to detect lost circulation, fluid influxes and other circulation problems in geothermal wells. This software platform has potential for significantly reducing geothermal drilling costs.
Calculation method for effect of silt sediment to lifting force of radial gate%淤泥对弧形钢闸门启门力影响的计算方法
Institute of Scientific and Technical Information of China (English)
徐国宾; 高仕赵
2012-01-01
为了估算泥沙淤积对弧形钢闸门启门力的影响,提出了一个计算公式.该公式将门前淤泥考虑为由粗细颗粒组成的宾汉体,同时考虑了泥沙附着力的力矩、梁格中附带泥沙重力的力矩、转动铰摩阻力的力矩、止水摩擦力矩、下吸力的力矩以及闸门重力和外加重力的力矩对弧形钢闸门启门力的影响.并利用该公式计算的弧形钢闸门启门力和西洱河二、四级电站泄洪闸门的实测资料进行对比得出:在门前泥沙淤积厚度较低的情况下,弧形钢闸门的启门力矩主要由闸门重力和外加重力决定,但是由泥沙引起的启门力矩变化也是不容忽视的,是导致闸门开启困难的影响因素之一,因此在设计过程中应充分考虑泥沙淤积对闸门启门力的影响,制定出合理的操作和维护方案,以防止闸门启闭困难情况的出现；该公式在计算门前有泥沙淤积情况下的启门力时,其计算精度能够满足工程实际需要.%In order to estimate the effect of silt sediment on the lifting force of steel radial gate, a calculating formula was proposed. In the formula, the silt deposited in front of the gate was considered to be the Bingham material which consists of coarse and fine particles. Also, the torques due to grillage sediment weight, rotational hinge friction resistance, seal friction resistance, under-suction effect, door weight and additio-nal-weight were torque etc were involved in the formula. The lifting forces applying on the sluicing steel radial gates in the 2nd and 4th Hydro-Power Station on the River Xi'er were estimated and compared with those measured in the stations. It was shown that in the case of less sediment deposition, the opening and closing torque on a radial gate is mainly decided by the door and additional-weight, but the lifting force caused from the sediment cannot be ignored. It is the sediment that leads to there is a difficulty in opening gate, thus it
Fluid-dynamic design optimization of hydraulic proportional directional valves
Amirante, Riccardo; Catalano, Luciano Andrea; Poloni, Carlo; Tamburrano, Paolo
2014-10-01
This article proposes an effective methodology for the fluid-dynamic design optimization of the sliding spool of a hydraulic proportional directional valve: the goal is the minimization of the flow force at a prescribed flow rate, so as to reduce the required opening force while keeping the operation features unchanged. A full three-dimensional model of the flow field within the valve is employed to accurately predict the flow force acting on the spool. A theoretical analysis, based on both the axial momentum equation and flow simulations, is conducted to define the design parameters, which need to be properly selected in order to reduce the flow force without significantly affecting the flow rate. A genetic algorithm, coupled with a computational fluid dynamics flow solver, is employed to minimize the flow force acting on the valve spool at the maximum opening. A comparison with a typical single-objective optimization algorithm is performed to evaluate performance and effectiveness of the employed genetic algorithm. The optimized spool develops a maximum flow force which is smaller than that produced by the commercially available valve, mainly due to some major modifications occurring in the discharge section. Reducing the flow force and thus the electromagnetic force exerted by the solenoid actuators allows the operational range of direct (single-stage) driven valves to be enlarged.
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.
A Hydraulic Blowdown Servo System For Launch Vehicle
Chen, Anping; Deng, Tao
2016-07-01
This paper introduced a hydraulic blowdown servo system developed for a solid launch vehicle of the family of Chinese Long March Vehicles. It's the thrust vector control (TVC) system for the first stage. This system is a cold gas blowdown hydraulic servo system and consist of gas vessel, hydraulic reservoir, servo actuator, digital control unit (DCU), electric explosion valve, and pressure regulator etc. A brief description of the main assemblies and characteristics follows. a) Gas vessel is a resin/carbon fiber composite over wrapped pressure vessel with a titanium liner, The volume of the vessel is about 30 liters. b) Hydraulic reservoir is a titanium alloy piston type reservoir with a magnetostrictive sensor as the fluid level indicator. The volume of the reservoir is about 30 liters. c) Servo actuator is a equal area linear piston actuator with a 2-stage low null leakage servo valve and a linear variable differential transducer (LVDT) feedback the piston position, Its stall force is about 120kN. d) Digital control unit (DCU) is a compact digital controller based on digital signal processor (DSP), and deployed dual redundant 1553B digital busses to communicate with the on board computer. e) Electric explosion valve is a normally closed valve to confine the high pressure helium gas. f) Pressure regulator is a spring-loaded poppet pressure valve, and regulates the gas pressure from about 60MPa to about 24MPa. g) The whole system is mounted in the aft skirt of the vehicle. h) This system delivers approximately 40kW hydraulic power, by contrast, the total mass is less than 190kg. the power mass ratio is about 0.21. Have finished the development and the system test. Bench and motor static firing tests verified that all of the performances have met the design requirements. This servo system is complaint to use of the solid launch vehicle.
Rotzoll, Kolja; Gingerich, Stephen B.; Jenson, John W.; El-Kadi, Aly I.
2013-01-01
Tidal-signal attenuations are analyzed to compute hydraulic diffusivities and estimate regional hydraulic conductivities of the Northern Guam Lens Aquifer, Territory of Guam (Pacific Ocean), USA. The results indicate a significant tidal-damping effect at the coastal boundary. Hydraulic diffusivities computed using a simple analytical solution for well responses to tidal forcings near the periphery of the island are two orders of magnitude lower than for wells in the island’s interior. Based on assigned specific yields of ~0.01–0.4, estimated hydraulic conductivities are ~20–800 m/day for peripheral wells, and ~2,000–90,000 m/day for interior wells. The lower conductivity of the peripheral rocks relative to the interior rocks may best be explained by the effects of karst evolution: (1) dissolutional enhancement of horizontal hydraulic conductivity in the interior; (2) case-hardening and concurrent reduction of local hydraulic conductivity in the cliffs and steeply inclined rocks of the periphery; and (3) the stronger influence of higher-conductivity regional-scale features in the interior relative to the periphery. A simple numerical model calibrated with measured water levels and tidal response estimates values for hydraulic conductivity and storage parameters consistent with the analytical solution. The study demonstrates how simple techniques can be useful for characterizing regional aquifer properties.
A fast direct numerical simulation method for characterising hydraulic roughness
Chung, Daniel; MacDonald, Michael; Hutchins, Nicholas; Ooi, Andrew
2015-01-01
We describe a fast direct numerical simulation (DNS) method that promises to directly characterise the hydraulic roughness of any given rough surface, from the hydraulically smooth to the fully rough regime. The method circumvents the unfavourable computational cost associated with simulating high-Reynolds-number flows by employing minimal-span channels (Jimenez & Moin 1991). Proof-of-concept simulations demonstrate that flows in minimal-span channels are sufficient for capturing the downward velocity shift, that is, the Hama roughness function, predicted by flows in full-span channels. We consider two sets of simulations, first with modelled roughness imposed by body forces, and second with explicit roughness described by roughness-conforming grids. Owing to the minimal cost, we are able to conduct DNSs with increasing roughness Reynolds numbers while maintaining a fixed blockage ratio, as is typical in full-scale applications. The present method promises a practical, fast and accurate tool for character...
Evaluation of Hydraulic Response of the Wave Dragon
DEFF Research Database (Denmark)
Frigaard, Peter; Kofoed, Jens Peter
The present study investigates the hydraulic response of the wave energy converter Wave Dragon. This is done by peforming model tests in a wave tank in the Hydraulics & Coastal Engineering Laboratory at Aalborg University. In the model tests a floating scale model (length scale 1:50) of the Wave...... Dragon is subjected to irregular, long crested irregular and short crested sea conditions corresponding to typical situations under which the Wave Dragon will produce power. Furthermore two situations corresponding to extreme storm conditions are tested. The objective of the study is to determine...... the wave induced forces in the moorings and in the junction between the reflectors and the reservoir part, and motions of the Wave Dragon situated in different sea conditions....
Evaluation of Hydraulic Response of the Wave Dragon
DEFF Research Database (Denmark)
Frigaard, Peter; Kofoed, Jens Peter
The present study investigates the hydraulic response of the wave energy converter Wave Dragon. This is done by peforming model tests in a wave tank in the Hydraulics & Coastal Engineering Laboratory at Aalborg University. In the model tests a floating scale model (length scale 1:50) of the Wave...... Dragon is subjected to irregular, long crested irregular and short crested sea conditions corresponding to typical situations under which the Wave Dragon will produce power. Furthermore two situations corresponding to extreme storm conditions are tested. The objective of the study is to determine...... the wave induced forces in the moorings and in the junction between the reflectors and the reservoir part, and motions of the Wave Dragon situated in different sea conditions....
Disturbance observer based position tracking of electro-hydraulic actuator
Institute of Scientific and Technical Information of China (English)
国凯; 魏建华; 田启岩
2015-01-01
A nonlinear controller based on an extended second-order disturbance observer is presented to track desired position for an electro-hydraulic single-rod actuator in the presence of both external disturbances and parameter uncertainties. The proposed extended second-order disturbance observer deals with not only the external perturbations, but also parameter uncertainties which are commonly regarded as lumped disturbances in previous researches. Besides, the outer position tracking loop is designed with cylinder load pressure as output; and the inner pressure control loop provides the hydraulic actuator the characteristic of a force generator. The stability of the closed-loop system is provided based on Lyapunov theory. The performance of the controller is verified through simulations and experiments. The results demonstrate that the proposed nonlinear position tracking controller, together with the extended second-order disturbance observer, gives an excellent tracking performance in the presence of parameter uncertainties and external disturbance.