Development of an optimal velocity selection method with velocity obstacle

Energy Technology Data Exchange (ETDEWEB)

Kim, Min Geuk; Oh, Jun Ho [KAIST, Daejeon (Korea, Republic of)

2015-08-15

The Velocity obstacle (VO) method is one of the most well-known methods for local path planning, allowing consideration of dynamic obstacles and unexpected obstacles. Typical VO methods separate a velocity map into a collision area and a collision-free area. A robot can avoid collisions by selecting its velocity from within the collision-free area. However, if there are numerous obstacles near a robot, the robot will have very few velocity candidates. In this paper, a method for choosing optimal velocity components using the concept of pass-time and vertical clearance is proposed for the efficient movement of a robot. The pass-time is the time required for a robot to pass by an obstacle. By generating a latticized available velocity map for a robot, each velocity component can be evaluated using a cost function that considers the pass-time and other aspects. From the output of the cost function, even a velocity component that will cause a collision in the future can be chosen as a final velocity if the pass-time is sufficiently long enough.

Effects of the concentration of emulsion of oil-in-water on the propagation velocity and attenuation

International Nuclear Information System (INIS)

Silva, L S F; Bibiano, D S; Figueiredo, M K K; Costa-Félix, R P B

2015-01-01

Soybean oil is an important feedstock for production of biodiesel that generates about 20 % of oily effluents. This paper studied the effect of concentration of soybean oil-inwater emulsions, in the range from 6 000 to 14 000 ppm, on the propagation velocity and ultrasonic attenuation. The Emission-Reception method has shown that the propagation velocity depends linearly on the concentration. The behavior of attenuation is similar to the velocity. Thus, both parameters can be used to measure oils and greases content in water

Complex relationship between groundwater velocity and concentration of radioactive contaminants

International Nuclear Information System (INIS)

Kaszeta, F.E.; Bond, F.W.

1980-01-01

This paper uses the results from the Multi-component Mass Transport model to examine the complex interrelationship between groundwater velocity and contaminant dispersion, decay, and retardation with regard to their influence on the contaminant concentration distribution as it travels through the geosphere to the biosphere. The rate of transport of contaminants through the geosphere is governed by groundwater velocity, leach rate, and contaminant retardation. The dominant characteristics of the contaminant concentration distribution are inherited during leaching and modified during transport by dilution, dispersion and decay. For a hypothetical non-decaying, non-dispersing contaminant with no retardation properties, the shape of the source term distribution is governed by the groundwater velocity (dilution) and leach rate. This distribution remains unchanged throughout transport. Under actual conditions, however, dispersion, decay and retardation modify the concentration distribution during both leaching and transport. The amount of dispersion is determined by the distance traveled, but it does have a greater peak-reducing influence on spiked distributions than square-shaped distributions. Decay acts as an overall scaling factor on the concentration distribution. Retardation alters the contaminant travel time and therefore indirectly influences the amount of dilution, dispersion and decay. Simple relationships between individual parameters and groundwater velocity as they influence peak concentration do not exist. For those cases where the source term is not solubility-limited and flow past the waste is independent of regional hydrologic conditions, a threshold concentration occurs at a specific groundwater velocity where the effects of dilution balance those of dispersion and decay

PDF methods for combustion in high-speed turbulent flows

Science.gov (United States)

Pope, Stephen B.

1995-01-01

This report describes the research performed during the second year of this three-year project. The ultimate objective of the project is extend the applicability of probability density function (pdf) methods from incompressible to compressible turbulent reactive flows. As described in subsequent sections, progress has been made on: (1) formulation and modelling of pdf equations for compressible turbulence, in both homogeneous and inhomogeneous inert flows; and (2) implementation of the compressible model in various flow configurations, namely decaying isotropic turbulence, homogeneous shear flow and plane mixing layer.

Uranyl adsorption kinetics within silica gel: dependence on flow velocity and concentration

Science.gov (United States)

Dodd, Brandon M.; Tepper, Gary

2017-09-01

Trace quantities of a uranyl dissolved in water were measured using a simple optical method. A dilute solution of uranium nitrate dissolved in water was forced through nanoporous silica gel at fixed and controlled water flow rates. The uranyl ions deposited and accumulated within the silica gel and the uranyl fluorescence within the silica gel was monitored as a function of time using a light emitting diode as the excitation source and a photomultiplier tube detector. It was shown that the response time of the fluorescence output signal at a particular volumetric flow rate or average liquid velocity through the silica gel can be used to quantify the concentration of uranium in water. The response time as a function of concentration decreased with increasing flow velocity.

Comparison of the Force-, Velocity- and Power-Time Curves Between the Concentric-Only and Eccentric-Concentric Bench Press Exercises.

Science.gov (United States)

Pérez-Castilla, Alejandro; Comfort, Paul; McMahon, John J; Pestaña-Melero, Francisco Luis; García-Ramos, Amador

2018-01-17

The aim of this study was to compare the temporal and mechanical variables between the concentric-only and eccentric-concentric bench press (BP) variants. Twenty-one men (age: 22.0±4.2 years, body mass: 73.4±7.7 kg, height: 177.2±8.0 cm; one-repetition maximum [1RM]: 1.12±0.12 kg⋅kg) were evaluated during the concentric-only and eccentric-concentric BP variants using 80% 1RM. Temporal (concentric phase duration, propulsive phase duration, and time to reach the maximum values of force, velocity, and power) and mechanical variables (force, velocity, and power), determined using a linear velocity transducer, were compared between both BP variants. All temporal variables were significantly lower during the eccentric-concentric BP compared to the concentric-only BP (P velocity and power were significantly higher for the eccentric-concentric BP compared to the concentric-only BP (all P velocity (ES: 0.40) and power (ES: 0.41). The stretch-shortening cycle (i.e., eccentric-concentric BP) mainly enhanced force production at the early portion of the concentric phase, but this potentiation effect gradually reduced over the latter part of the movement. Finally, force was higher for the concentric-only BP during 49% of the concentric phase duration. These results suggest that both BP variants should be included during resistance training programs in order to optimize force output at different points of the concentric phase.

Comparison of PDF and Moment Closure Methods in the Modeling of Turbulent Reacting Flows

Science.gov (United States)

Norris, Andrew T.; Hsu, Andrew T.

1994-01-01

In modeling turbulent reactive flows, Probability Density Function (PDF) methods have an advantage over the more traditional moment closure schemes in that the PDF formulation treats the chemical reaction source terms exactly, while moment closure methods are required to model the mean reaction rate. The common model used is the laminar chemistry approximation, where the effects of turbulence on the reaction are assumed negligible. For flows with low turbulence levels and fast chemistry, the difference between the two methods can be expected to be small. However for flows with finite rate chemistry and high turbulence levels, significant errors can be expected in the moment closure method. In this paper, the ability of the PDF method and the moment closure scheme to accurately model a turbulent reacting flow is tested. To accomplish this, both schemes were used to model a CO/H2/N2- air piloted diffusion flame near extinction. Identical thermochemistry, turbulence models, initial conditions and boundary conditions are employed to ensure a consistent comparison can be made. The results of the two methods are compared to experimental data as well as to each other. The comparison reveals that the PDF method provides good agreement with the experimental data, while the moment closure scheme incorrectly shows a broad, laminar-like flame structure.

Heavy Metal and PAH Concentrations in Highway Runoff Deposits Fractionated on Settling Velocities

DEFF Research Database (Denmark)

Bentzen, Thomas Ruby; Larsen, Torben

2009-01-01

The correlation between settling velocity and associated pollutant concentrations is of major importance for best management practice in designing, redesigning, or evaluation of the efficiency of existing pond facilities for retaining unwanted pollutants. The prospect of this note is to state...... the relationship between the settling velocity of the runoff particles and the corresponding metal and polyaromatic hydrocarbon (PAH) concentration directly instead of dealing with two unknowns-the density and the shape of a single particle fraction in a settling velocity calculations. The measurements show...... and copper and there is no significant correlation between PAH concentration and settling velocity. The largest mass of metals and PAH within each pond can be found on the particle fraction with a settling velocity of 5.5-2.5 mm/s....

Hybrid finite-volume/transported PDF method for the simulation of turbulent reactive flows

Science.gov (United States)

Raman, Venkatramanan

A novel computational scheme is formulated for simulating turbulent reactive flows in complex geometries with detailed chemical kinetics. A Probability Density Function (PDF) based method that handles the scalar transport equation is coupled with an existing Finite Volume (FV) Reynolds-Averaged Navier-Stokes (RANS) flow solver. The PDF formulation leads to closed chemical source terms and facilitates the use of detailed chemical mechanisms without approximations. The particle-based PDF scheme is modified to handle complex geometries and grid structures. Grid-independent particle evolution schemes that scale linearly with the problem size are implemented in the Monte-Carlo PDF solver. A novel algorithm, in situ adaptive tabulation (ISAT) is employed to ensure tractability of complex chemistry involving a multitude of species. Several non-reacting test cases are performed to ascertain the efficiency and accuracy of the method. Simulation results from a turbulent jet-diffusion flame case are compared against experimental data. The effect of micromixing model, turbulence model and reaction scheme on flame predictions are discussed extensively. Finally, the method is used to analyze the Dow Chlorination Reactor. Detailed kinetics involving 37 species and 158 reactions as well as a reduced form with 16 species and 21 reactions are used. The effect of inlet configuration on reactor behavior and product distribution is analyzed. Plant-scale reactors exhibit quenching phenomena that cannot be reproduced by conventional simulation methods. The FV-PDF method predicts quenching accurately and provides insight into the dynamics of the reactor near extinction. The accuracy of the fractional time-stepping technique in discussed in the context of apparent multiple-steady states observed in a non-premixed feed configuration of the chlorination reactor.

Computing discharge using the index velocity method

Science.gov (United States)

Levesque, Victor A.; Oberg, Kevin A.

2012-01-01

Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression

PDF -- new peat technology

Energy Technology Data Exchange (ETDEWEB)

Myreen, P B

1982-12-01

The impact of a large-scale utilization of peat must be assessed in each region separately. As it is completely impractical to transport wet peat over long distances, a PDF plant must be built in the peatland region. Such regions often need economic stimulation. The PDF process can be run independent of season and weather, and thus offers permanent jobs. Dredging the peat layer all at once in a wet state is an operation concentrated on a very small land area. If this area can be drained, it can soon afterwards be forested or used for agricultural purposes. Even if the area from which the peat is removed is left as a wetland, when cleverly done, the ecological effects may be favourable. Peat is a significant energy source in many countries now looking for domestic alternatives to expensive imported fuels. The main constraint on large-scale utilization of peat is its ability to retain moisture. The wet-carbonization process, utilized in a PDF plant and yielding a high-quality peat-derived fuel, is believed to be a technically feasible and economically attractive industrial method of dewatering native peat.

Estimation of the variations of ventilation rate and indoor radon concentration using the observed wind velocity and indoor-outdoor temperature difference

International Nuclear Information System (INIS)

Nagano, Katsuhiro; Inose, Yuichi; Kojima, Hiroshi

2006-01-01

The indoor radon concentration in the building depends on the ventilation rate. Measurement results of indoor-outdoor pressure difference showed the ventilation rate correlated closely with the indoor-outdoor pressure difference. The observation results showed that one of factor of indoor-outdoor pressure difference was the wind velocity. When the wind velocity is small, the ventilation rate is affected by the indoor-outdoor temperature difference and the effect depends on the wind velocity. The temporal variation of indoor radon concentration was predicted by the time depending indoor radon balance model and the ventilation rate estimated from the wind velocity and the indoor-outdoor temperature difference. The temporal variations of predicted radon concentration gave good agreement with the experimental values. The measurement method, indoor radon concentration and ventilation rate, factors of temporal variation of ventilation rate, and prediction of indoor radon concentration are reported. (S.Y.)

Asymptotic stability of spectral-based PDF modeling for homogeneous turbulent flows

Science.gov (United States)

Campos, Alejandro; Duraisamy, Karthik; Iaccarino, Gianluca

2015-11-01

Engineering models of turbulence, based on one-point statistics, neglect spectral information inherent in a turbulence field. It is well known, however, that the evolution of turbulence is dictated by a complex interplay between the spectral modes of velocity. For example, for homogeneous turbulence, the pressure-rate-of-strain depends on the integrated energy spectrum weighted by components of the wave vectors. The Interacting Particle Representation Model (IPRM) (Kassinos & Reynolds, 1996) and the Velocity/Wave-Vector PDF model (Van Slooten & Pope, 1997) emulate spectral information in an attempt to improve the modeling of turbulence. We investigate the evolution and asymptotic stability of the IPRM using three different approaches. The first approach considers the Lagrangian evolution of individual realizations (idealized as particles) of the stochastic process defined by the IPRM. The second solves Lagrangian evolution equations for clusters of realizations conditional on a given wave vector. The third evolves the solution of the Eulerian conditional PDF corresponding to the aforementioned clusters. This last method avoids issues related to discrete particle noise and slow convergence associated with Lagrangian particle-based simulations.

Exploration of probability distribution of velocities of saltating sand particles based on the stochastic particle-bed collisions

International Nuclear Information System (INIS)

Zheng Xiaojing; Xie Li; Zhou Youhe

2005-01-01

The wind-blown sand saltating movement is mainly categorized into two mechanical processes, that is, the interaction between the moving sand particles and the wind in the saltation layer, and the collisions of incident particles with sand bed, and the latter produces a lift-off velocity of a sand particle moving into saltation. In this Letter a methodology of phenomenological analysis is presented to get probability density (distribution) function (pdf) of the lift-off velocity of sand particles from sand bed based on the stochastic particle-bed collision. After the sand particles are dealt with by uniform circular disks and a 2D collision between an incident particle and the granular bed is employed, we get the analytical formulas of lift-off velocity of ejected and rebound particles in saltation, which are functions of some random parameters such as angle and magnitude of incident velocity of the impacting particles, impact and contact angles between the collision particles, and creeping velocity of sand particles, etc. By introducing the probability density functions (pdf's) of these parameters in communion with all possible patterns of sand bed and all possible particle-bed collisions, and using the essential arithmetic of multi-dimension random variables' pdf, the pdf's of lift-off velocities are deduced out and expressed by the pdf's of the random parameters in the collisions. The numerical results of the distributions of lift-off velocities display that they agree well with experimental ones

Compressible cavitation with stochastic field method

Science.gov (United States)

Class, Andreas; Dumond, Julien

2012-11-01

Non-linear phenomena can often be well described using probability density functions (pdf) and pdf transport models. Traditionally the simulation of pdf transport requires Monte-Carlo codes based on Lagrange particles or prescribed pdf assumptions including binning techniques. Recently, in the field of combustion, a novel formulation called the stochastic field method solving pdf transport based on Euler fields has been proposed which eliminates the necessity to mix Euler and Lagrange techniques or prescribed pdf assumptions. In the present work, part of the PhD Design and analysis of a Passive Outflow Reducer relying on cavitation, a first application of the stochastic field method to multi-phase flow and in particular to cavitating flow is presented. The application considered is a nozzle subjected to high velocity flow so that sheet cavitation is observed near the nozzle surface in the divergent section. It is demonstrated that the stochastic field formulation captures the wide range of pdf shapes present at different locations. The method is compatible with finite-volume codes where all existing physical models available for Lagrange techniques, presumed pdf or binning methods can be easily extended to the stochastic field formulation.

External intermittency prediction using AMR solutions of RANS turbulence and transported PDF models

Science.gov (United States)

Olivieri, D. A.; Fairweather, M.; Falle, S. A. E. G.

2011-12-01

External intermittency in turbulent round jets is predicted using a Reynolds-averaged Navier-Stokes modelling approach coupled to solutions of the transported probability density function (pdf) equation for scalar variables. Solutions to the descriptive equations are obtained using a finite-volume method, combined with an adaptive mesh refinement algorithm, applied in both physical and compositional space. This method contrasts with conventional approaches to solving the transported pdf equation which generally employ Monte Carlo techniques. Intermittency-modified eddy viscosity and second-moment turbulence closures are used to accommodate the effects of intermittency on the flow field, with the influence of intermittency also included, through modifications to the mixing model, in the transported pdf equation. Predictions of the overall model are compared with experimental data on the velocity and scalar fields in a round jet, as well as against measurements of intermittency profiles and scalar pdfs in a number of flows, with good agreement obtained. For the cases considered, predictions based on the second-moment turbulence closure are clearly superior, although both turbulence models give realistic predictions of the bimodal scalar pdfs observed experimentally.

PDF methods for turbulent reactive flows

Science.gov (United States)

Hsu, Andrew T.

1995-01-01

Viewgraphs are presented on computation of turbulent combustion, governing equations, closure problem, PDF modeling of turbulent reactive flows, validation cases, current projects, and collaboration with industry and technology transfer.

Evaluation of a Consistent LES/PDF Method Using a Series of Experimental Spray Flames

Science.gov (United States)

Heye, Colin; Raman, Venkat

2012-11-01

A consistent method for the evolution of the joint-scalar probability density function (PDF) transport equation is proposed for application to large eddy simulation (LES) of turbulent reacting flows containing evaporating spray droplets. PDF transport equations provide the benefit of including the chemical source term in closed form, however, additional terms describing LES subfilter mixing must be modeled. The recent availability of detailed experimental measurements provide model validation data for a wide range of evaporation rates and combustion regimes, as is well-known to occur in spray flames. In this work, the experimental data will used to investigate the impact of droplet mass loading and evaporation rates on the subfilter scalar PDF shape in comparison with conventional flamelet models. In addition, existing model term closures in the PDF transport equations are evaluated with a focus on their validity in the presence of regime changes.

An experimental study of low concentration sludge settling velocity under turbulent condition.

Science.gov (United States)

Guo, Lisha; Zhang, Daijun; Xu, Danyu; Chen, Yuan

2009-05-01

Particle Image Velocimetry (PIV) was used to study the settling of activated sludge flocs under turbulent flow conditions. Experimental results showed that a larger particle diameter led to a higher settling velocity while the higher turbulence intensity led to lower settling velocity. Based on the measurements a mathematical relation has been derived which correlates the settling velocity for individual sludge flocs under turbulent conditions through a modified Vesilind equation. Settling velocity shows a power-type relation to sludge particle diameter and an exponential-type relation with turbulence intensity and sludge concentration.

Gas-hydrate concentration estimated from P- and S-wave velocities at the Mallik 2L-38 research well, Mackenzie Delta, Canada

Science.gov (United States)

Carcione, José M.; Gei, Davide

2004-05-01

We estimate the concentration of gas hydrate at the Mallik 2L-38 research site using P- and S-wave velocities obtained from well logging and vertical seismic profiles (VSP). The theoretical velocities are obtained from a generalization of Gassmann's modulus to three phases (rock frame, gas hydrate and fluid). The dry-rock moduli are estimated from the log profiles, in sections where the rock is assumed to be fully saturated with water. We obtain hydrate concentrations up to 75%, average values of 37% and 21% from the VSP P- and S-wave velocities, respectively, and 60% and 57% from the sonic-log P- and S-wave velocities, respectively. The above averages are similar to estimations obtained from hydrate dissociation modeling and Archie methods. The estimations based on the P-wave velocities are more reliable than those based on the S-wave velocities.

Ultrasonic device for real-time sewage velocity and suspended particles concentration measurements.

Science.gov (United States)

Abda, F; Azbaid, A; Ensminger, D; Fischer, S; François, P; Schmitt, P; Pallarès, A

2009-01-01

In the frame of a technological research and innovation network in water and environment technologies (RITEAU, Réseau de Recherche et d'Innovation Technologique Eau et Environnement), our research group, in collaboration with industrial partners and other research institutions, has been in charge of the development of a suitable flowmeter: an ultrasonic device measuring simultaneously the water flow and the concentration of size classes of suspended particles. Working on the pulsed ultrasound principle, our multi-frequency device (1 to 14 MHz) allows flow velocity and water height measurement and estimation of suspended solids concentration. Velocity measurements rely on the coherent Doppler principle. A self developed frequency estimator, so called Spectral Identification method, was used and compared to the classical Pulse-Pair method. Several measurements campaigns on one wastewater collector of the French city of Strasbourg gave very satisfactory results and showed smaller standard deviation values for the Doppler frequency extracted by the Spectral Identification method. A specific algorithm was also developed for the water height measurements. It relies on the water surface acoustic impedance rupture and its peak localisation and behaviour in the collected backscattering data. This algorithm was positively tested on long time measurements on the same wastewater collector. A large part of the article is devoted to the measurements of the suspended solids concentrations. Our data analysis consists in the adaptation of the well described acoustic behaviour of sand to the behaviour of wastewater particles. Both acoustic attenuation and acoustic backscattering data over multiple frequencies are analyzed for the extrapolation of size classes and respective concentrations. Under dry weather conditions, the massic backscattering coefficient and the overall size distribution showed similar evolution whatever the measurement site was and were suggesting a global

Modeling the Bergeron-Findeisen Process Using PDF Methods With an Explicit Representation of Mixing

Science.gov (United States)

Jeffery, C.; Reisner, J.

2005-12-01

Currently, the accurate prediction of cloud droplet and ice crystal number concentration in cloud resolving, numerical weather prediction and climate models is a formidable challenge. The Bergeron-Findeisen process in which ice crystals grow by vapor deposition at the expense of super-cooled droplets is expected to be inhomogeneous in nature--some droplets will evaporate completely in centimeter-scale filaments of sub-saturated air during turbulent mixing while others remain unchanged [Baker et al., QJRMS, 1980]--and is unresolved at even cloud-resolving scales. Despite the large body of observational evidence in support of the inhomogeneous mixing process affecting cloud droplet number [most recently, Brenguier et al., JAS, 2000], it is poorly understood and has yet to be parameterized and incorporated into a numerical model. In this talk, we investigate the Bergeron-Findeisen process using a new approach based on simulations of the probability density function (PDF) of relative humidity during turbulent mixing. PDF methods offer a key advantage over Eulerian (spatial) models of cloud mixing and evaporation: the low probability (cm-scale) filaments of entrained air are explicitly resolved (in probability space) during the mixing event even though their spatial shape, size and location remain unknown. Our PDF approach reveals the following features of the inhomogeneous mixing process during the isobaric turbulent mixing of two parcels containing super-cooled water and ice, respectively: (1) The scavenging of super-cooled droplets is inhomogeneous in nature; some droplets evaporate completely at early times while others remain unchanged. (2) The degree of total droplet evaporation during the initial mixing period depends linearly on the mixing fractions of the two parcels and logarithmically on Damköhler number (Da)---the ratio of turbulent to evaporative time-scales. (3) Our simulations predict that the PDF of Lagrangian (time-integrated) subsaturation (S) goes as

A new method for measurement of granular velocities

International Nuclear Information System (INIS)

Nyborg Andersen, B.

1984-01-01

A new, supplementary method to measure granular velocities is presented. The method utilizes the Doppler shift caused by the line of sight component of the solar rotation to cause a wavelength shift through spectral lines as function of heliocentric angle. By measuring the center-to-limb variation of the granular intensity fluctations at different wavelength positions in the lines, the velocities are found. To do this, assumptions regarding the geometrical structure of the velocity and intensity fields have to be made. Preliminary application of the method results in a steep velocity gradient suggesting zero velocity at a hight of 200 km above tau 500 = 1. Possible causes are discussed

The effect of lipid emulsion of different concentration on blood flow velocity: an experimental study

International Nuclear Information System (INIS)

Li Qiang; Wang Maoqiang; Duan Liuxin; Song Peng; Ao Guokun

2009-01-01

Objective: To investigate the function mechanism of lipid emulsion (LE), used as a carrier, by observing the effect of intra-arterial infusion of LE in different concentration and dosage on blood flow velocity. Methods: According to the concentration and dosage used in arterial infusion, the experiments were divided into four groups:group A (20% LE, 2 ml), group B (20% LE, 20 ml), group C (30% LE, 2 ml) and group D (30% LE, 20 ml). Two healthy hybrid dogs were used for the study. Under DSA guidance, the 4 F catheter was placed in the splenic artery and in the hepatic artery respectively. DSA frames were counted in order to calculate the time that the contrast took from the catheter tip to the selected tertiary branches of the splenic or hepatic artery. Results LE infusion, regardless of its concentration level or its dosage, could reduce the blood velocity. The lasting time and the maximal peak value of the blood velocity reduction were significantly different among groups (P < 0.05). The lasting time was 5 minutes, 5-10 minutes, 20 minutes and 20-30 minutes among group A, B, C and D, respectively. The peak value of the reduction appeared at the 18th frames (1.44 s), 30th frames (2.4 s), 9th frames (0.9 s) and 14th frames (1.12 s) in group A, B, C and D, respectively. Conclusion Intra-arterial infusion of LE can reduce the blood flow velocity. The lasting time of the reduction in 30% LE groups is longer than that in 20% LE groups, while the blood velocity reduction in 30% LE groups is less than that in 20% LE groups. (authors)

Feasibility of using acoustic velocity meters for estimating highly organic suspended-solids concentrations in streams

Science.gov (United States)

Patino, Eduardo

1996-01-01

A field experiment was conducted at the Levee 4 canal site below control structure G-88 in the Everglades agricultural area in northwestern Broward County, Florida, to study the relation of acoustic attenuation to suspended-solids concentrations. Acoustic velocity meter and temperature data were obtained with concurrent water samples analyzed for suspended-solids concentrations. Two separate acoustic velocity meter frequencies were used, 200 and 500 kilohertz, to determine the sensitivity of acoustic attenuation to frequency for the measured suspended-solids concentration range. Suspended-solids concentrations for water samples collected at the Levee 4 canal site from July 1993 to September 1994 ranged from 22 to 1,058 milligrams per liter, and organic content ranged from about 30 to 93 percent. Regression analyses showed that attenuation data from the acoustic velocity meter (automatic gain control) and temperature data alone do not provide enough information to adequately describe the concentrations of suspended solids. However, if velocity is also included as one of the independent variables in the regression model, a satisfactory correlation can be obtained. Thus, it is feasible to use acoustic velocity meter instrumentation to estimate suspended-solids concentrations in streams, even when suspended solids are primarily composed of organic material. Using the most comprehensive data set available for the study (500 kiloherz data), the best fit regression model produces a standard error of 69.7 milligrams per liter, with actual errors ranging from 2 to 128 milligrams per liter. Both acoustic velocity meter transmission frequencies of 200 and 500 hilohertz produced similar results, suggesting that transducers of either frequency could be used to collect attenuation data at the study site. Results indicate that calibration will be required for each acoustic velocity meter system to the unique suspended-solids regime existing at each site. More robust solutions may

Point and planar LIF for velocity-concentration correlations in a jet in cross flow

DEFF Research Database (Denmark)

Meyer, Knud Erik; Özcan, Oktay; Larsen, Poul Scheel

2002-01-01

Simultaneous measurements of velocities and concentration with Planar Laser Induced Fluorescense (PLIF) combined with Particle Image Velocimetry (PIV) are compared to similar measurements with pointwise Laser Induced Fluorescense (LIF) made with a slightly modified standard Laser Doppler Anemometer......, since these involve areas with high velocity- and concentration gradients, which in turn amplifies the effect of a finite measurement volume in the two measurement systems. In addition, the concentration measurement was realized by injecting clean water into the dye seeded main flow. This "inverse...

Probability and Cumulative Density Function Methods for the Stochastic Advection-Reaction Equation

Energy Technology Data Exchange (ETDEWEB)

Barajas-Solano, David A.; Tartakovsky, Alexandre M.

2018-01-01

We present a cumulative density function (CDF) method for the probabilistic analysis of $d$-dimensional advection-dominated reactive transport in heterogeneous media. We employ a probabilistic approach in which epistemic uncertainty on the spatial heterogeneity of Darcy-scale transport coefficients is modeled in terms of random fields with given correlation structures. Our proposed CDF method employs a modified Large-Eddy-Diffusivity (LED) approach to close and localize the nonlocal equations governing the one-point PDF and CDF of the concentration field, resulting in a $(d + 1)$ dimensional PDE. Compared to the classsical LED localization, the proposed modified LED localization explicitly accounts for the mean-field advective dynamics over the phase space of the PDF and CDF. To illustrate the accuracy of the proposed closure, we apply our CDF method to one-dimensional single-species reactive transport with uncertain, heterogeneous advection velocities and reaction rates modeled as random fields.

Surface wave velocity tracking by bisection method

International Nuclear Information System (INIS)

Maeda, T.

2005-01-01

Calculation of surface wave velocity is a classic problem dating back to the well-known Haskell's transfer matrix method, which contributes to solutions of elastic wave propagation, global subsurface structure evaluation by simulating observed earthquake group velocities, and on-site evaluation of subsurface structure by simulating phase velocity dispersion curves and/or H/V spectra obtained by micro-tremor observation. Recently inversion analysis on micro-tremor observation requires efficient method of generating many model candidates and also stable, accurate, and fast computation of dispersion curves and Raleigh wave trajectory. The original Haskell's transfer matrix method has been improved in terms of its divergence tendency mainly by the generalized transmission and reflection matrix method with formulation available for surface wave velocity; however, root finding algorithm has not been fully discussed except for the one by setting threshold to the absolute value of complex characteristic functions. Since surface wave number (reciprocal to the surface wave velocity multiplied by frequency) is a root of complex valued characteristic function, it is intractable to use general root finding algorithm. We will examine characteristic function in phase plane to construct two dimensional bisection algorithm with consideration on a layer to be evaluated and algorithm for tracking roots down along frequency axis. (author)

Effects of resistance training using known vs unknown loads on eccentric-phase adaptations and concentric velocity.

Science.gov (United States)

Hernández-Davó, J L; Sabido, R; Behm, D G; Blazevich, A J

2018-02-01

The aims of this study were to compare both eccentric- and concentric-phase adaptations in highly trained handball players to 4 weeks of twice-weekly rebound bench press throw training with varying loads (30%, 50% and 70% of one-repetition maximum [1-RM]) using either known (KL) or unknown (UL) loads and to examine the relationship between changes in eccentric- and concentric-phase performance. Twenty-eight junior team handball players were divided into two experimental groups (KL or UL) and a control group. KL subjects were told the load prior each repetition, while UL were blinded. For each repetition, the load was dropped and then a rebound bench press at maximum velocity was immediately performed. Both concentric and eccentric velocity as well as eccentric kinetic energy and musculo-articular stiffness prior to the eccentric-concentric transition were measured. Results showed similar increases in both eccentric velocity and kinetic energy under the 30% 1-RM but greater improvements under 50% and 70% 1-RM loads for UL than KL. UL increased stiffness under all loads (with greater magnitude of changes). KL improved concentric velocity only under the 30% 1-RM load while UL also improved under 50% and 70% 1-RM loads. Improvements in concentric movement velocity were moderately explained by changes in eccentric velocity (R 2 =.23-.62). Thus, UL led to greater improvements in concentric velocity, and the improvement is potentially explained by increases in the speed (as well as stiffness and kinetic energy) of the eccentric phase. Unknown load training appears to have significant practical use for the improvement of multijoint stretch-shortening cycle movements. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The Prescribed Velocity Method

DEFF Research Database (Denmark)

Nielsen, Peter Vilhelm

The- velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactory...

A mixing method for traceable air velocity measurements

International Nuclear Information System (INIS)

Sillanpää, S; Heinonen, M

2008-01-01

A novel and quite simple method to establish a traceability link between air velocity and the national standards of mass and time is presented in this paper. The method is based on the humidification of flowing air before the blower of a wind tunnel with a known mass flow of water. Then air velocity can be calculated as a function of humidification water flow. The method is compared against a Pitot-tube-based velocity measurement in a wind tunnel at the MIKES. The results of these two different methods agreed well, with a maximum difference of 0.7%

Sediment acoustic index method for computing continuous suspended-sediment concentrations

Science.gov (United States)

Landers, Mark N.; Straub, Timothy D.; Wood, Molly S.; Domanski, Marian M.

2016-07-11

Suspended-sediment characteristics can be computed using acoustic indices derived from acoustic Doppler velocity meter (ADVM) backscatter data. The sediment acoustic index method applied in these types of studies can be used to more accurately and cost-effectively provide time-series estimates of suspended-sediment concentration and load, which is essential for informed solutions to many sediment-related environmental, engineering, and agricultural concerns. Advantages of this approach over other sediment surrogate methods include: (1) better representation of cross-sectional conditions from large measurement volumes, compared to other surrogate instruments that measure data at a single point; (2) high temporal resolution of collected data; (3) data integrity when biofouling is present; and (4) less rating curve hysteresis compared to streamflow as a surrogate. An additional advantage of this technique is the potential expansion of monitoring suspended-sediment concentrations at sites with existing ADVMs used in streamflow velocity monitoring. This report provides much-needed standard techniques for sediment acoustic index methods to help ensure accurate and comparable documented results.

On conditional scalar increment and joint velocity-scalar increment statistics

International Nuclear Information System (INIS)

Zhang Hengbin; Wang Danhong; Tong Chenning

2004-01-01

Conditional velocity and scalar increment statistics are usually studied in the context of Kolmogorov's refined similarity hypotheses and are considered universal (quasi-Gaussian) for inertial-range separations. In such analyses the locally averaged energy and scalar dissipation rates are used as conditioning variables. Recent studies have shown that certain local turbulence structures can be captured when the local scalar variance (φ 2 ) r and the local kinetic energy k r are used as the conditioning variables. We study the conditional increments using these conditioning variables, which also provide the local turbulence scales. Experimental data obtained in the fully developed region of an axisymmetric turbulent jet are used to compute the statistics. The conditional scalar increment probability density function (PDF) conditional on (φ 2 ) r is found to be close to Gaussian for (φ 2 ) r small compared with its mean and is sub-Gaussian and bimodal for large (φ 2 ) r , and therefore is not universal. We find that the different shapes of the conditional PDFs are related to the instantaneous degree of non-equilibrium (production larger than dissipation) of the local scalar. There is further evidence of this from the conditional PDF conditional on both (φ 2 ) r and χ r , which is largely a function of (φ 2 ) r /χ r , a measure of the degree of non-equilibrium. The velocity-scalar increment joint PDF is close to joint Gaussian and quad-modal for equilibrium and non-equilibrium local velocity and scalar, respectively. The latter shape is associated with a combination of the ramp-cliff and plane strain structures. Kolmogorov's refined similarity hypotheses also predict a dependence of the conditional PDF on the degree of non-equilibrium. Therefore, the quasi-Gaussian (joint) PDF, previously observed in the context of Kolmogorov's refined similarity hypotheses, is only one of the conditional PDF shapes of inertial range turbulence. The present study suggests that

Analysis of subgrid scale mixing using a hybrid LES-Monte-Carlo PDF method

International Nuclear Information System (INIS)

Olbricht, C.; Hahn, F.; Sadiki, A.; Janicka, J.

2007-01-01

This contribution introduces a hybrid LES-Monte-Carlo method for a coupled solution of the flow and the multi-dimensional scalar joint pdf in two complex mixing devices. For this purpose an Eulerian Monte-Carlo method is used. First, a complex mixing device (jet-in-crossflow, JIC) is presented in which the stochastic convergence and the coherency between the scalar field solution obtained via finite-volume methods and that from the stochastic solution of the pdf for the hybrid method are evaluated. Results are compared to experimental data. Secondly, an extensive investigation of the micromixing on the basis of assumed shape and transported SGS-pdfs in a configuration with practical relevance is carried out. This consists of a mixing chamber with two opposite rows of jets penetrating a crossflow (multi-jet-in-crossflow, MJIC). Some numerical results are compared to available experimental data and to RANS based results. It turns out that the hybrid LES-Monte-Carlo method could achieve a detailed analysis of the mixing at the subgrid level

The present state and future directions of PDF methods

Science.gov (United States)

Pope, S. B.

1992-01-01

The objectives of the workshop are presented in viewgraph format, as is this entire article. The objectives are to discuss the present status and the future direction of various levels of engineering turbulence modeling related to Computational Fluid Dynamics (CFD) computations for propulsion; to assure that combustion is an essential part of propulsion; and to discuss Probability Density Function (PDF) methods for turbulent combustion. Essential to the integration of turbulent combustion models is the development of turbulent model, chemical kinetics, and numerical method. Some turbulent combustion models typically used in industry are the k-epsilon turbulent model, the equilibrium/mixing limited combustion, and the finite volume codes.

Transported PDF Modeling of Ethanol Spray in Hot-Diluted Coflow Flame

OpenAIRE

Ma, L.; Naud, B.; Roekaerts, D.J.E.M.

2015-01-01

This paper presents a numerical modeling study of one ethanol spray flame from the Delft Spray-in-Hot-Coflow (DSHC) database, which has been used to study Moderate or Intense Low-oxygen Dilution (MILD) combustion of liquid fuels (Correia Rodrigues et al. Combust. Flame 162(3), 759–773, 2015). A “Lagrangian-Lagrangian” approach is adopted where both the joint velocity-scalar Probability Density Function (PDF) for the continuous phase and the joint PDF of droplet properties are modeled and solv...

Analysis of a PDF model in a mixing layer case

International Nuclear Information System (INIS)

Minier, J.P.; Pozorski, J.

1996-04-01

A recent turbulence model put forward by Pope (1991) in the context of PDF modeling has been applied to a mixing layer case. This model solves the one-point joint velocity-dissipation pdf equation by simulating the instantaneous behaviour of a large number of Lagrangian fluid particles. Closure of the evolution equations of these Lagrangian particles is based on diffusion stochastic processes. The paper reports numerical results and tries to analyse the physical meaning of some variables, in particular the dissipation-weighted kinetic energy and its relation with external intermittency. (authors). 14 refs., 7 figs

Manifold methods for methane combustion

Energy Technology Data Exchange (ETDEWEB)

Yang, B.; Pope, S.B. [Cornell Univ., Ithaca, NY (United States)

1995-10-01

Great progresses have been made in combustion research, especially, the computation of laminar flames and the probability density function (PDF) method in turbulent combustion. For one-dimensional laminar flames, by considering the transport mechanism, the detailed chemical kinetic mechanism and the interactions between these two basic processes, today it is a routine matter to calculate flame velocities, extinction, ignition, temperature, and species distributions from the governing equations. Results are in good agreement with those obtained for experiments. However, for turbulent combustion, because of the complexities of turbulent flow, chemical reactions, and the interaction between them, in the foreseeable future, it is impossible to calculate the combustion flow field by directly integrating the basic governing equations. So averaging and modeling are necessary in turbulent combustion studies. Averaging, on one hand, simplifies turbulent combustion calculations, on the other hand, it introduces the infamous closure problems, especially the closure problem with chemical reaction terms. Since in PDF calculations of turbulent combustion, the averages of the chemical reaction terms can be calculated, PDF methods overcome the closure problem with the reaction terms. It has been shown that the PDF method is a most promising method to calculate turbulent combustion. PDF methods have been successfully employed to calculate laboratory turbulent flames: they can predict phenomena such as super equilibrium radical levels, and local extinction. Because of these advantages, PDF methods are becoming used increasingly in industry combustor codes.

A study of the river velocity measurement techniques and analysis methods

Science.gov (United States)

Chung Yang, Han; Lun Chiang, Jie

2013-04-01

Velocity measurement technology can be traced back to the pitot tube velocity measurement method in the 18th century and today's velocity measurement technology use the acoustic and radar technology, with the Doppler principle developed technology advances, in order to develop the measurement method is more suitable for the measurement of velocity, the purpose is to get a more accurate measurement data and with the surface velocity theory, the maximum velocity theory and the indicator theory to obtain the mean velocity. As the main research direction of this article is to review the literature of the velocity measurement techniques and analysis methods, and to explore the applicability of the measurement method of the velocity measurement instruments, and then to describe the advantages and disadvantages of the different mean velocity profiles analysis method. Adequate review of the references of this study will be able to provide a reference for follow-up study of the velocity measurement. Review velocity measurement literature that different velocity measurement is required to follow the different flow conditions measured be upgraded its accuracy, because each flow rate measurement method has its advantages and disadvantages. Traditional velocity instrument can be used at low flow and RiverRAD microwave radar or imaging technology measurement method may be applied in high flow. In the tidal river can use the ADCP to quickly measure river vertical velocity distribution. In addition, urban rivers may be used the CW radar to set up on the bridge, and wide rivers can be used RiverRAD microwave radar to measure the velocities. Review the relevant literature also found that using Ultrasonic Doppler Current Profiler with the Chiu's theory to the velocity of observing automation work can save manpower and resources to improve measurement accuracy, reduce the risk of measurement, but the great variability of river characteristics in Taiwan and a lot of drifting floating

Regularity of particle velocity decrease with scale d distance for rockbursts and shot holes

Czech Academy of Sciences Publication Activity Database

Holub, Karel; Rušajová, Jana

2015-01-01

Roč. 20, č. 2 (2015), s. 80-85 ISSN 1335-1788 Institutional support: RVO:68145535 Keywords : rockburst * hole shot * particle velocity * scaled distance * cylindrical and spherical waveforms Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.390, year: 2015 http://actamont.tuke.sk/pdf/2015/n2/2holub.pdf

A revised method to calculate the concentration time integral of atmospheric pollutants

International Nuclear Information System (INIS)

Voelz, E.; Schultz, H.

1980-01-01

It is possible to calculate the spreading of a plume in the atmosphere under nonstationary and nonhomogeneous conditions by introducing the ''particle-in-cell'' method (PIC). This is a numerical method by which the transport of and the diffusion in the plume is reproduced in such a way, that particles representing the concentration are moved time step-wise in restricted regions (cells) and separately with the advection velocity and the diffusion velocity. This has a systematical advantage over the steady state Gaussian plume model usually used. The fixed-point concentration time integral is calculated directly instead of being substituted by the locally integrated concentration at a constant time as is done in the Gaussian model. In this way inaccuracies due to the above mentioned computational techniques may be avoided for short-time emissions, as may be seen by the fact that both integrals do not lead to the same results. Also the PIC method enables one to consider the height-dependent wind speed and its variations while the Gaussian model can be used only with averaged wind data. The concentration time integral calculated by the PIC method results in higher maximum values in shorter distances to the source. This is an effect often observed in measurements. (author)

PDF Explained

CERN Document Server

Whitington, John

2011-01-01

An introduction to the PDF file format, threaded through with practical examples - deconstructing, creating and processing PDF files. After exploring how PDF is produced, and how it can be edited with tools from text editors to Ghostscript to PDFTK, readers will learn to deal with problems with PDF files and common error messages.

The spatial filtering method for solid particle velocity measurement based on an electrostatic sensor

International Nuclear Information System (INIS)

Xu, Chuanlong; Tang, Guanghua; Zhou, Bin; Wang, Shimin

2009-01-01

The spatial filtering method for particle velocity measurement has the advantages of simplicity of the measurement system and convenience of data processing. In this paper, the relationship between solid particles mean velocity in a pneumatic pipeline and the power spectrum of the output signal of an electrostatic sensor was mathematically modeled. The effects of the length of the sensor, the thickness of the dielectric pipe and its length on the spatial filtering characteristics of the sensor were also investigated using the finite element method. As for the roughness of and the difficult determination of the peak frequency f max of the power spectrum characteristics of the output signal of the sensor, a wavelet analysis based filtering method was applied to smooth the curve, which can accurately determine the peak frequency f max . Finally, experiments were performed on a pilot dense phase pneumatic conveying rig at high pressure to test the performance of the velocity measurement system. The experimental results show that the system repeatability is within ±4% over a gas superficial velocity range of 8.63–18.62 m s −1 for a particle concentration range of 0.067–0.130 m 3 m −3

Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

International Nuclear Information System (INIS)

Bin Mohamad, Edy Tonnizam; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia; Saad, Rosli

2010-01-01

Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

Excavatability Assessment of Weathered Sedimentary Rock Mass Using Seismic Velocity Method

Science.gov (United States)

Bin Mohamad, Edy Tonnizam; Saad, Rosli; Noor, Muhazian Md; Isa, Mohamed Fauzi Bin Md.; Mazlan, Ain Naadia

2010-12-01

Seismic refraction method is one of the most popular methods in assessing surface excavation. The main objective of the seismic data acquisition is to delineate the subsurface into velocity profiles as different velocity can be correlated to identify different materials. The physical principal used for the determination of excavatability is that seismic waves travel faster through denser material as compared to less consolidated material. In general, a lower velocity indicates material that is soft and a higher velocity indicates more difficult to be excavated. However, a few researchers have noted that seismic velocity method alone does not correlate well with the excavatability of the material. In this study, a seismic velocity method was used in Nusajaya, Johor to assess the accuracy of this seismic velocity method with excavatability of the weathered sedimentary rock mass. A direct ripping run by monitoring the actual production of ripping has been employed at later stage and compared to the ripper manufacturer's recommendation. This paper presents the findings of the seismic velocity tests in weathered sedimentary area. The reliability of using this method with the actual rippability trials is also presented.

Wind-induced flow velocity effects on nutrient concentrations at Eastern Bay of Lake Taihu, China.

Science.gov (United States)

Jalil, Abdul; Li, Yiping; Du, Wei; Wang, Jianwei; Gao, Xiaomeng; Wang, Wencai; Acharya, Kumud

2017-07-01

Shallow lakes are highly sensitive to respond internal nutrient loading due to wind-induced flow velocity effects. Wind-induced flow velocity effects on nutrient suspension were investigated at a long narrow bay of large shallow Lake Taihu, the third largest freshwater lake in China. Wind-induced reverse/compensation flow and consistent flow field probabilities at vertical column of the water were measured. The probabilities between the wind field and the flow velocities provided a strong correlation at the surface (80.6%) and the bottom (65.1%) layers of water profile. Vertical flow velocity profile analysis provided the evidence of delay response time to wind field at the bottom layer of lake water. Strong wind field generated by the west (W) and west-north-west (WNW) winds produced displaced water movements in opposite directions to the prevailing flow field. An exponential correlation was observed between the current velocities of the surface and the bottom layers while considering wind speed as a control factor. A linear model was developed to correlate the wind field-induced flow velocity impacts on nutrient concentration at the surface and bottom layers. Results showed that dominant wind directions (ENE, E, and ESE) had a maximum nutrient resuspension contribution (nutrient resuspension potential) of 34.7 and 43.6% at the surface and the bottom profile layers, respectively. Total suspended solids (TSS), total nitrogen (TN), and total phosphorus (TP) average concentrations were 6.38, 1.5, and 0.03 mg/L during our field experiment at Eastern Bay of Lake Taihu. Overall, wind-induced low-to-moderate hydrodynamic disturbances contributed more in nutrient resuspension at Eastern Bay of Lake Taihu. The present study can be used to understand the linkage between wind-induced flow velocities and nutrient concentrations for shallow lakes (with uniform morphology and deep margins) water quality management and to develop further models.

Comparison of different methods for the determination of dynamic characteristics of low velocity anemometers

DEFF Research Database (Denmark)

Melikov, Arsen Krikor; Popiolek, Z.

2004-01-01

Three methods for determining the dynamic characteristics of low velocity thermal anemometers were compared. They were: step-up velocity change and step-down velocity change methods and a method based on sinusoidal type velocity fluctuations. Two low velocity thermal anemometers with omnidirectio......Three methods for determining the dynamic characteristics of low velocity thermal anemometers were compared. They were: step-up velocity change and step-down velocity change methods and a method based on sinusoidal type velocity fluctuations. Two low velocity thermal anemometers...... with omnidirectional velocity sensors were tested. The results identify differences in frequency response of low velocity anemometers determined by the three methods. The time constant and the response time determined by the step-up velocity change method and the step-down velocity change method may be substantially...... different and insufficient for describing the frequency response of all low velocity thermal anemometers. Therefore the upper frequency, determined in tests with sinusoidal velocity fluctuations, is recommended to be used in indoor climate standards as a single parameter describing the dynamic...

Measurements of ammonia concentrations, fluxes and dry deposition velocities to a spruce forest 1991-1995

DEFF Research Database (Denmark)

Andersen, H.V.; Hovmand, M.F.; Hummelshøj, P.

1999-01-01

The dry deposition velocities and fluxes of ammonia have been estimated from measurements of the vertical gradient of ammonia and micrometeorology above a spruce forest in western Jutland, Denmark. Measurements have been made in seven periods, each lasting about one week and covering all seasons...... measuring period characterized by easterly winds with dry conditions and high ammonia concentrations, and the emissions might relate to evaporation from ammonia saturated surfaces or emission from mineralization in the forest soil. In general, relatively high net deposition velocities were observed during...... at conditions with easterly winds, the air have passed central Jutland with large emission areas. Some of the relatively low deposition velocities or emissions were observed during conditions with low ammonia concentration and westerly winds. These observations might relate to a compensation point of the forest...

Size, velocity, and concentration in suspension measurements of spherical droplets and cylindrical jets.

Science.gov (United States)

Onofri, F; Bergougnoux, L; Firpo, J L; Misguich-Ripault, J

1999-07-20

The principle of an optical technique for simultaneous velocity, size, and concentration in suspension measurements of spherical droplets and cylindrical jets is proposed. This technique is based on phase Doppler anemometry working in the dual burst technique configuration. The particle size and velocity are deduced from the reflected signal phase and frequency, whereas the amplitude ratio between the refracted and the reflected signals is used for measuring the concentration of small scatterers inside the particles. Numerical simulations, based on geometrical optics and a Monte Carlo model, and an experimental validation test on cylindrical jets made of various suspensions, are used to validate the principle of the proposed technique. It is believed that this new technique could be useful in investigating processes in which liquid suspensions are sprayed for surface coating, drying, or combustion applications.

A novel background field removal method for MRI using projection onto dipole fields (PDF).

Science.gov (United States)

Liu, Tian; Khalidov, Ildar; de Rochefort, Ludovic; Spincemaille, Pascal; Liu, Jing; Tsiouris, A John; Wang, Yi

2011-11-01

For optimal image quality in susceptibility-weighted imaging and accurate quantification of susceptibility, it is necessary to isolate the local field generated by local magnetic sources (such as iron) from the background field that arises from imperfect shimming and variations in magnetic susceptibility of surrounding tissues (including air). Previous background removal techniques have limited effectiveness depending on the accuracy of model assumptions or information input. In this article, we report an observation that the magnetic field for a dipole outside a given region of interest (ROI) is approximately orthogonal to the magnetic field of a dipole inside the ROI. Accordingly, we propose a nonparametric background field removal technique based on projection onto dipole fields (PDF). In this PDF technique, the background field inside an ROI is decomposed into a field originating from dipoles outside the ROI using the projection theorem in Hilbert space. This novel PDF background removal technique was validated on a numerical simulation and a phantom experiment and was applied in human brain imaging, demonstrating substantial improvement in background field removal compared with the commonly used high-pass filtering method. Copyright © 2011 John Wiley & Sons, Ltd.

A consistent transported PDF model for treating differential molecular diffusion

Science.gov (United States)

Wang, Haifeng; Zhang, Pei

2016-11-01

Differential molecular diffusion is a fundamentally significant phenomenon in all multi-component turbulent reacting or non-reacting flows caused by the different rates of molecular diffusion of energy and species concentrations. In the transported probability density function (PDF) method, the differential molecular diffusion can be treated by using a mean drift model developed by McDermott and Pope. This model correctly accounts for the differential molecular diffusion in the scalar mean transport and yields a correct DNS limit of the scalar variance production. The model, however, misses the molecular diffusion term in the scalar variance transport equation, which yields an inconsistent prediction of the scalar variance in the transported PDF method. In this work, a new model is introduced to remedy this problem that can yield a consistent scalar variance prediction. The model formulation along with its numerical implementation is discussed, and the model validation is conducted in a turbulent mixing layer problem.

Mean Velocity vs. Mean Propulsive Velocity vs. Peak Velocity: Which Variable Determines Bench Press Relative Load With Higher Reliability?

Science.gov (United States)

García-Ramos, Amador; Pestaña-Melero, Francisco L; Pérez-Castilla, Alejandro; Rojas, Francisco J; Gregory Haff, G

2018-05-01

García-Ramos, A, Pestaña-Melero, FL, Pérez-Castilla, A, Rojas, FJ, and Haff, GG. Mean velocity vs. mean propulsive velocity vs. peak velocity: which variable determines bench press relative load with higher reliability? J Strength Cond Res 32(5): 1273-1279, 2018-This study aimed to compare between 3 velocity variables (mean velocity [MV], mean propulsive velocity [MPV], and peak velocity [PV]): (a) the linearity of the load-velocity relationship, (b) the accuracy of general regression equations to predict relative load (%1RM), and (c) the between-session reliability of the velocity attained at each percentage of the 1-repetition maximum (%1RM). The full load-velocity relationship of 30 men was evaluated by means of linear regression models in the concentric-only and eccentric-concentric bench press throw (BPT) variants performed with a Smith machine. The 2 sessions of each BPT variant were performed within the same week separated by 48-72 hours. The main findings were as follows: (a) the MV showed the strongest linearity of the load-velocity relationship (median r = 0.989 for concentric-only BPT and 0.993 for eccentric-concentric BPT), followed by MPV (median r = 0.983 for concentric-only BPT and 0.980 for eccentric-concentric BPT), and finally PV (median r = 0.974 for concentric-only BPT and 0.969 for eccentric-concentric BPT); (b) the accuracy of the general regression equations to predict relative load (%1RM) from movement velocity was higher for MV (SEE = 3.80-4.76%1RM) than for MPV (SEE = 4.91-5.56%1RM) and PV (SEE = 5.36-5.77%1RM); and (c) the PV showed the lowest within-subjects coefficient of variation (3.50%-3.87%), followed by MV (4.05%-4.93%), and finally MPV (5.11%-6.03%). Taken together, these results suggest that the MV could be the most appropriate variable for monitoring the relative load (%1RM) in the BPT exercise performed in a Smith machine.

Simulations of Spray Reacting Flows in a Single Element LDI Injector With and Without Invoking an Eulerian Scalar PDF Method

Science.gov (United States)

Shih, Tsan-Hsing; Liu, Nan-Suey

2012-01-01

This paper presents the numerical simulations of the Jet-A spray reacting flow in a single element lean direct injection (LDI) injector by using the National Combustion Code (NCC) with and without invoking the Eulerian scalar probability density function (PDF) method. The flow field is calculated by using the Reynolds averaged Navier-Stokes equations (RANS and URANS) with nonlinear turbulence models, and when the scalar PDF method is invoked, the energy and compositions or species mass fractions are calculated by solving the equation of an ensemble averaged density-weighted fine-grained probability density function that is referred to here as the averaged probability density function (APDF). A nonlinear model for closing the convection term of the scalar APDF equation is used in the presented simulations and will be briefly described. Detailed comparisons between the results and available experimental data are carried out. Some positive findings of invoking the Eulerian scalar PDF method in both improving the simulation quality and reducing the computing cost are observed.

Textural behavior of gels formed by rice starch and whey protein isolate: Concentration and crosshead velocities

Directory of Open Access Journals (Sweden)

Thiago Novaes Silva

Full Text Available ABSTRACT Fabricated food gels involving the use of hydrocolloids are gaining polpularity as confectionery/convenience foods. Starch is commonly combined with a hydrocolloid (protein our polyssacharides, particularly in the food industry, since native starches generally do not have ideal properties for the preparation of food products. Therefore the texture studies of starch-protein mixtures could provide a new approach in producing starch-based food products, being thus acritical attribute that needs to be carefully adjusted to the consumer liking. This work investigated the texture and rheological properties of mixed gels of different concentrations of rice starch (15%, 17.5%, and 20% and whey protein isolate (0%, 3%, and 6% with different crosshead velocities (0.05, 5.0, and 10.0 mm/s using a Box-Behnken experimental design. The samples were submitted to uniaxial compression tests with 80% deformation in order to determinate the following rheological parameters: Young’s modulus, fracture stress, fracture deformation, recoverable energy, and apparent biaxial elongational viscosity. Gels with a higher rice starch concentration that were submitted to higher test velocities were more rigid and resistant, while the whey protein isolate concentration had little influence on these properties. The gels showed a higher recoverable energy when the crosshead velocity was higher, and the apparent biaxial elongational viscosity was also influenced by this factor. Therefore, mixed gels exhibit different properties depending on the rice starch concentration and crosshead velocity.

Effect of flow velocity, substrate concentration and hydraulic cleaning on biofouling of reverse osmosis feed channels

KAUST Repository

Radu, Andrea I.

2012-04-01

A two-dimensional mathematical model coupling fluid dynamics, salt and substrate transport and biofilm development in time was used to investigate the effects of cross-flow velocity and substrate availability on biofouling in reverse osmosis (RO)/nanofiltration (NF) feed channels. Simulations performed in channels with or without spacer filaments describe how higher liquid velocities lead to less overall biomass amount in the channel by increasing the shear stress. In all studied cases at constant feed flow rate, biomass accumulation in the channel reached a steady state. Replicate simulation runs prove that the stochastic biomass attachment model does not affect the stationary biomass level achieved and has only a slight influence on the dynamics of biomass accumulation. Biofilm removal strategies based on velocity variations are evaluated. Numerical results indicate that sudden velocity increase could lead to biomass sloughing, followed however by biomass re-growth when returning to initial operating conditions. Simulations show particularities of substrate availability in membrane devices used for water treatment, e.g., the accumulation of rejected substrates at the membrane surface due to concentration polarization. Interestingly, with an increased biofilm thickness, the overall substrate consumption rate dominates over accumulation due to substrate concentration polarization, eventually leading to decreased substrate concentrations in the biofilm compared to bulk liquid. © 2012 Elsevier B.V.

Money velocity in an endogenous growth business cycle with credit shocks

Czech Academy of Sciences Publication Activity Database

Benk, S.; Gillman, M.; Kejak, Michal

-, CDMC06/04 (2006), s. 1-39 Institutional research plan: CEZ:AV0Z70850503 Keywords : money velocity * business cycle * endogenous growth Subject RIV: AH - Economics http://www.st- and rews.ac.uk/economics/CDMA/papers/cp0604.pdf

Planar measurements of velocity and concentration of turbulent mixing in a T-junction

DEFF Research Database (Denmark)

Ingvorsen, Kristian Mark; Meyer, Knud Erik; Nielsen, N. F.

Turbulent mixing of two isothermal air streams in a T-junction of square ducts are investigated. Three dimensional velocity fields and turbulent kinetic energy are measured with stereoscopic Particle Image Velocimetry (PIV). The concentration field is obtained with a planar Mie scattering technique...

Money velocity in an endogenous growth business cycle with credit shocks

Czech Academy of Sciences Publication Activity Database

Benk, S.; Gillman, M.; Kejak, Michal

-, E2007/14 (2007), s. 1-16 ISSN 1749-6101 Institutional research plan: CEZ:MSM0021620846 Keywords : money velocity * business cycle * credit shocks Subject RIV: AH - Economics http://www.cf.ac.uk/carbs/econ/workingpapers/papers/E2007_14.pdf

Surface wave phase velocities between Bulgaria and the Czech Republic

Czech Academy of Sciences Publication Activity Database

Gaždová, Renata; Kolínský, Petr; Popova, I.; Dimitrova, L.

2011-01-01

Roč. 18, č. 2 (2011), s. 16-23 ISSN 1803-1447. [OVA´11 – New Knowledge and Measurements in Seismology, Engineering Geophysics and Geotechnics. Ostrava, 12.04.2011-14.04.2011] R&D Projects: GA ČR GA205/09/1244 Institutional research plan: CEZ:AV0Z30460519 Keywords : surface waves * phase velocity * shear wave velocity Subject RIV: DC - Siesmology, Volcanology, Earth Structure http://www.caag.cz/egrse/2011-2/03%20gazdova_ova.pdf

Visual feedback attenuates mean concentric barbell velocity loss, and improves motivation, competitiveness, and perceived workload in male adolescent athletes.

Science.gov (United States)

Weakley, Jonathon Js; Wilson, Kyle M; Till, Kevin; Read, Dale B; Darrall-Jones, Joshua; Roe, Gregory; Phibbs, Padraic J; Jones, Ben

2017-07-12

It is unknown whether instantaneous visual feedback of resistance training outcomes can enhance barbell velocity in younger athletes. Therefore, the purpose of this study was to quantify the effects of visual feedback on mean concentric barbell velocity in the back squat, and to identify changes in motivation, competitiveness, and perceived workload. In a randomised-crossover design (Feedback vs. Control) feedback of mean concentric barbell velocity was or was not provided throughout a set of 10 repetitions in the barbell back squat. Magnitude-based inferences were used to assess changes between conditions, with almost certainly greater differences in mean concentric velocity between the Feedback (0.70 ±0.04 m·s) and Control (0.65 ±0.05 m·s) observed. Additionally, individual repetition mean concentric velocity ranged from possibly (repetition number two: 0.79 ±0.04 vs. 0.78 ±0.04 m·s) to almost certainly (repetition number 10: 0.58 ±0.05 vs. 0.49 ±0.05 m·s) greater when provided feedback, while almost certain differences were observed in motivation, competitiveness, and perceived workload, respectively. Providing adolescent male athletes with visual kinematic information while completing resistance training is beneficial for the maintenance of barbell velocity during a training set, potentially enhancing physical performance. Moreover, these improvements were observed alongside increases in motivation, competitiveness and perceived workload providing insight into the underlying mechanisms responsible for the performance gains observed. Given the observed maintenance of barbell velocity during a training set, practitioners can use this technique to manipulate training outcomes during resistance training.

A New Method for Estimation of Velocity Vectors

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt; Munk, Peter

1998-01-01

The paper describes a new method for determining the velocity vector of a remotely sensed object using either sound or electromagnetic radiation. The movement of the object is determined from a field with spatial oscillations in both the axial direction of the transducer and in one or two...... directions transverse to the axial direction. By using a number of pulse emissions, the inter-pulse movement can be estimated and the velocity found from the estimated movement and the time between pulses. The method is based on the principle of using transverse spatial modulation for making the received...

A Measuring Method About the Bullet Velocity in Electromagnetic Rail Gun

Directory of Open Access Journals (Sweden)

Jianming LIU

2014-02-01

Full Text Available The operating principle of electromagnetic rail gun by store capacitor was analyzed. A simulation model about the bullet velocity in the electromagnetic rail gun was built. The results of computer simulation experiment showed the relationships between the bullet velocity and the capacitor charging voltage and the pellet mass. By ten coil targets, a new kind of measuring method for the bullet velocity in electromagnetic rail gun was presented. The results of the actual experiment were analyzed. The improving method for measuring bullet velocity was put forward.

Acoustic methods for measuring bullet velocity

OpenAIRE

Courtney, Michael

2008-01-01

This article describes two acoustic methods to measure bullet velocity with an accuracy of 1% or better. In one method, a microphone is placed within 0.1 m of the gun muzzle and a bullet is fired at a steel target 45 m away. The bullet's flight time is the recorded time between the muzzle blast and sound of hitting the target minus the time for the sound to return from the target to the microphone. In the other method, the microphone is placed equidistant from both the gun muzzle and the stee...

The determination methods of the velocity constant for electrochemical reactions

International Nuclear Information System (INIS)

Molina, R.

1963-01-01

In a brief introduction are recalled the fundamental mechanisms of the electrochemical reaction and the definition of the intrinsic velocity constant of a such reaction. By the nature of the different parameters which enter in this definition are due some experimental problems which are examined. Then are given the principles of the measurement methods of the velocity constant. These methods are developed with the mathematical expression of the different rates of the mass transfer to an electrode. In each case are given the experimental limits of use of the methods and the size order of the velocity constant that can be reached. A list of fundamental works to be consulted conclude this work. (O.M.) [fr

Evaluation of Maryland abutment scour equation through selected threshold velocity methods

Science.gov (United States)

Benedict, S.T.

2010-01-01

The U.S. Geological Survey, in cooperation with the Maryland State Highway Administration, used field measurements of scour to evaluate the sensitivity of the Maryland abutment scour equation to the critical (or threshold) velocity variable. Four selected methods for estimating threshold velocity were applied to the Maryland abutment scour equation, and the predicted scour to the field measurements were compared. Results indicated that performance of the Maryland abutment scour equation was sensitive to the threshold velocity with some threshold velocity methods producing better estimates of predicted scour than did others. In addition, results indicated that regional stream characteristics can affect the performance of the Maryland abutment scour equation with moderate-gradient streams performing differently from low-gradient streams. On the basis of the findings of the investigation, guidance for selecting threshold velocity methods for application to the Maryland abutment scour equation are provided, and limitations are noted.

INFLUENCE OF HEXAVALENT CHROMIUM INITIAL CONCENTRATION ON RETARDATION FACTOR AND CONTAMINANT VELOCITY IN A SOIL MEDIA

Directory of Open Access Journals (Sweden)

K. SHIVA PRASHANTH KUMAR

2016-02-01

Full Text Available Sources of soil and ground water contamination are many and include many folds of accidental spills and leaks of toxic and hazardous chemicals. Preparation of ground water contamination model needs good understanding of the behavior of contaminant transport through soil media for predicting the level of contamination of ground water in the near future at the intended site conditions. Sorption is a natural process; due to its presence, the contaminant can move slowly as compared to the ground water and hence the effects of sorption must be taken into consideration while predicting the travel time of the contaminant to reach the ground water sources. This paper discusses the results of column test studies carried out in the laboratory under controlled conditions about the spreading of contaminant (Hexavalent chromium, Cr (VI through the clay mixed red soil at two different initial concentrations (800 mg/L and 4200 mg/L. The variations of the contaminant flow velocity and retardation factor for two different initial concentrations of contaminant were brought out and discussed. The contaminant flow velocity drastically coming down for a relative concentration of 0 to 0.2 and beyond this range, the contaminant flow velocity value is decreasing in a slow rate for both the lower and higher initial contaminant concentrations tested. At the lower relative concentration, the higher retardation factor was observed and it may be due to slowly filling the available sorption sites in the soil column.

A Novel Method for Determining the Gas Transfer Velocity of Carbon Dioxide in Streams

Science.gov (United States)

McDowell, M. J.; Johnson, M. S.

2016-12-01

Characterization of the global carbon cycle relies on the accurate quantification of carbon fluxes into and out of natural and human-dominated ecosystems. Among these fluxes, carbon dioxide (CO2) evasion from surface water has received increasing attention in recent years. However, limitations of current methods, including determination of the gas transfer velocity (k), compromise our ability to evaluate the significance of CO2 fluxes between freshwater systems and the atmosphere. We developed an automated method to determine gas transfer velocities of CO2 (kCO2), and tested it under a range of flow conditions for a first-order stream of a headwater catchment in southwestern British Columbia, Canada. Our method uses continuous in situ measurements of CO2 concentrations using two non-dispersive infrared (NDIR) sensors enclosed in water impermeable, gas permeable membranes (Johnson et al., 2010) downstream from a gas diffuser. CO2 was injected into the stream at regular intervals via a compressed gas tank connected to the diffuser. CO2 injections were controlled by a datalogger at fixed time intervals and in response to storm-induced changes in streamflow. Following the injection, differences in CO2 concentrations at known distances downstream from the diffuser relative to pre-injection baseline levels allowed us to calculate kCO2. Here we present relationships between kCO2 and hydro-geomorphologic (flow velocity, streambed slope, stream width, stream depth), atmospheric (wind speed and direction), and water quality (stream temperature, pH, electrical conductivity) variables. This method has advantages of being automatable and field-deployable, and it does not require supplemental gas chromatography, as is the case for propane injections typically used to determine k. The dataset presented suggests the potential role of this method to further elucidate the role that CO2 fluxes from headwater streams play in the global carbon cycle. Johnson, M. S., Billett, M. F

An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors

Directory of Open Access Journals (Sweden)

Jian Li

2015-12-01

Full Text Available The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

New Methods for Estimating Water Current Velocity Fields from Autonomous Underwater Vehicles

Science.gov (United States)

Kinsey, J. C.; Medagoda, L.

2016-02-01

Water current velocities are a crucial component of understanding oceanographic processes and underwater robots, such as autonomous underwater vehicles (AUVs), provide a mobile platform for obtaining these observations. Estimating water current velocities requires both measurements of the water velocity, often obtained with an Acoustic Doppler Current Profiler (ADCP), as well as estimates of the vehicle velocity. Presently, vehicle velocities are supplied on the sea surface with velocity from GPS, or near the seafloor where Doppler Velocity Log (DVL) in bottom-lock is available; however, this capability is unavailable in the mid-water column where DVL bottom-lock and GPS are unavailable. Here we present a method which calculates vehicle velocities using consecutive ADCP measurements in the mid-water using an extended Kalman filter (EKF). The correlation of the spatially changing water current states, along with mass transport and shear constraints on the water current field, is formulated using least square constraints. Results from the Sentry AUV from a mid-water surveying mission at Deepwater Horizon and a small-scale hydrothermal vent flux estimation mission suggest the method is suitable for real-time use. DVL data is denied to simulate mid-water missions and the results compared to ground truth water velocity measurements estimated using DVL velocities. Results show quantifiable uncertainties in the water current velocities, along with similar performance, for the DVL and no-DVL case in the mid-water. This method has the potential to provide geo-referenced water velocity measurements from mobile ocean robots in the absence of GPS and DVL as well as estimate the uncertainty associated with the measurements.

Quantifying Diastolic Function: From E-Waves as Triangles to Physiologic Contours via the 'Geometric Method'.

Science.gov (United States)

Golman, Mikhail; Padovano, William; Shmuylovich, Leonid; Kovács, Sándor J

2018-03-01

Conventional echocardiographic diastolic function (DF) assessment approximates transmitral flow velocity contours (Doppler E-waves) as triangles, with peak (E peak ), acceleration time (AT), and deceleration time (DT) as indexes. These metrics have limited value because they are unable to characterize the underlying physiology. The parametrized diastolic filling (PDF) formalism provides a physiologic, kinematic mechanism based characterization of DF by extracting chamber stiffness (k), relaxation (c), and load (x o ) from E-wave contours. We derive the mathematical relationship between the PDF parameters and E peak , AT, DT and thereby introduce the geometric method (GM) that computes the PDF parameters using E peak , AT, and DT as input. Numerical experiments validated GM by analysis of 208 E-waves from 31 datasets spanning the full range of clinical diastolic function. GM yielded indistinguishable average parameter values per subject vs. the gold-standard PDF method (k: R 2  = 0.94, c: R 2  = 0.95, x o : R 2  = 0.95, p PDF method to quantify DF in terms of physiologic chamber properties.

A multi-scalar PDF approach for LES of turbulent spray combustion

Science.gov (United States)

Raman, Venkat; Heye, Colin

2011-11-01

A comprehensive joint-scalar probability density function (PDF) approach is proposed for large eddy simulation (LES) of turbulent spray combustion and tests are conducted to analyze the validity and modeling requirements. The PDF method has the advantage that the chemical source term appears closed but requires models for the small scale mixing process. A stable and consistent numerical algorithm for the LES/PDF approach is presented. To understand the modeling issues in the PDF method, direct numerical simulation of a spray flame at three different fuel droplet Stokes numbers and an equivalent gaseous flame are carried out. Assumptions in closing the subfilter conditional diffusion term in the filtered PDF transport equation are evaluated for various model forms. In addition, the validity of evaporation rate models in high Stokes number flows is analyzed.

A method to standardize gait and balance variables for gait velocity.

NARCIS (Netherlands)

Iersel, M.B. van; Olde Rikkert, M.G.M.; Borm, G.F.

2007-01-01

Many gait and balance variables depend on gait velocity, which seriously hinders the interpretation of gait and balance data derived from walks at different velocities. However, as far as we know there is no widely accepted method to correct for effects of gait velocity on other gait and balance

Money velocity in an endogenous growth business cycle with credit shocks

Czech Academy of Sciences Publication Activity Database

Benk, S.; Gillman, M.; Kejak, Michal

-, 2007/5 (2007), s. 1-17 ISSN 1585-5600 R&D Projects: GA MŠk LC542 Institutional research plan: CEZ:MSM0021620846 Keywords : money velocity * business cycle * credit shocks Subject RIV: AH - Economics http://www.mnb.hu/Root/Dokumentumtar/MNB/Kiadvanyok/mnbhu_mnbfuzetek/WP_2007_5.pdf

A method to estimate stellar ages from kinematical data

Science.gov (United States)

Almeida-Fernandes, F.; Rocha-Pinto, H. J.

2018-05-01

We present a method to build a probability density function (PDF) for the age of a star based on its peculiar velocities U, V, and W and its orbital eccentricity. The sample used in this work comes from the Geneva-Copenhagen Survey (GCS) that contains the spatial velocities, orbital eccentricities, and isochronal ages for about 14 000 stars. Using the GCS stars, we fitted the parameters that describe the relations between the distributions of kinematical properties and age. This parametrization allows us to obtain an age probability from the kinematical data. From this age PDF, we estimate an individual average age for the star using the most likely age and the expected age. We have obtained the stellar age PDF for the age of 9102 stars from the GCS and have shown that the distribution of individual ages derived from our method is in good agreement with the distribution of isochronal ages. We also observe a decline in the mean metallicity with our ages for stars younger than 7 Gyr, similar to the one observed for isochronal ages. This method can be useful for the estimation of rough stellar ages for those stars that fall in areas of the Hertzsprung-Russell diagram where isochrones are tightly crowded. As an example of this method, we estimate the age of Trappist-1, which is a M8V star, obtaining the age of t(UVW) = 12.50(+0.29 - 6.23) Gyr.

Proposed method for reconstructing velocity profiles using a multi-electrode electromagnetic flow meter

International Nuclear Information System (INIS)

Kollár, László E; Lucas, Gary P; Zhang, Zhichao

2014-01-01

An analytical method is developed for the reconstruction of velocity profiles using measured potential distributions obtained around the boundary of a multi-electrode electromagnetic flow meter (EMFM). The method is based on the discrete Fourier transform (DFT), and is implemented in Matlab. The method assumes the velocity profile in a section of a pipe as a superposition of polynomials up to sixth order. Each polynomial component is defined along a specific direction in the plane of the pipe section. For a potential distribution obtained in a uniform magnetic field, this direction is not unique for quadratic and higher-order components; thus, multiple possible solutions exist for the reconstructed velocity profile. A procedure for choosing the optimum velocity profile is proposed. It is applicable for single-phase or two-phase flows, and requires measurement of the potential distribution in a non-uniform magnetic field. The potential distribution in this non-uniform magnetic field is also calculated for the possible solutions using weight values. Then, the velocity profile with the calculated potential distribution which is closest to the measured one provides the optimum solution. The reliability of the method is first demonstrated by reconstructing an artificial velocity profile defined by polynomial functions. Next, velocity profiles in different two-phase flows, based on results from the literature, are used to define the input velocity fields. In all cases, COMSOL Multiphysics is used to model the physical specifications of the EMFM and to simulate the measurements; thus, COMSOL simulations produce the potential distributions on the internal circumference of the flow pipe. These potential distributions serve as inputs for the analytical method. The reconstructed velocity profiles show satisfactory agreement with the input velocity profiles. The method described in this paper is most suitable for stratified flows and is not applicable to axisymmetric flows in

Humic acid transport in saturated porous media: influence of flow velocity and influent concentration.

Science.gov (United States)

Wei, Xiaorong; Shao, Mingan; Du, Lina; Horton, Robert

2014-12-01

Understanding the transport of humic acids (HAs) in porous media can provide important and practical evidence needed for accurate prediction of organic/inorganic contaminant transport in different environmental media and interfaces. A series of column transport experiments was conducted to evaluate the transport of HA in different porous media at different flow velocities and influent HA concentrations. Low flow velocity and influent concentration were found to favor the adsorption and deposition of HA onto sand grains packed into columns and to give higher equilibrium distribution coefficients and deposition rate coefficients, which resulted in an increased fraction of HA being retained in columns. Consequently, retardation factors were increased and the transport of HA through the columns was delayed. These results suggest that the transport of HA in porous media is primarily controlled by the attachment of HA to the solid matrix. Accordingly, this attachment should be considered in studies of HA behavior in porous media. Copyright © 2014. Published by Elsevier B.V.

Determination of velocity vector angles using the directional cross-correlation method

DEFF Research Database (Denmark)

Kortbek, Jacob; Jensen, Jørgen Arendt

2005-01-01

and then select the angle with the highest normalized correlation between directional signals. The approach is investigated using Field II simulations and data from the experimental ultrasound scanner RASMUS and with a parabolic flow having a peak velocity of 0.3 m/s. A 7 MHz linear array transducer is used......A method for determining both velocity magnitude and angle in any direction is suggested. The method uses focusing along the velocity direction and cross-correlation for finding the correct velocity magnitude. The angle is found from beamforming directional signals in a number of directions......-time ) between signals to correlate, and a proper choice varies with flow angle and flow velocity. One performance example is given with a fixed value of k tprf for all flow angles. The angle estimation on measured data for flow at 60 ◦ to 90 ◦ , yields a probability of valid estimates between 68% and 98...

Estimation of velocity vector angles using the directional cross-correlation method

DEFF Research Database (Denmark)

Kortbek, Jacob; Jensen, Jørgen Arendt

2006-01-01

and then select the angle with the highest normalized correlation between directional signals. The approach is investigated using Field II simulations and data from the experimental ultrasound scanner RASMUS and a circulating flow rig with a parabolic flow having a peak velocity of 0.3 m/s. A 7 MHz linear array......A method for determining both velocity magnitude and angle in any direction is suggested. The method uses focusing along the velocity direction and cross-correlation for finding the correct velocity magnitude. The angle is found from beamforming directional signals in a number of directions...... transducer is used with a normal transmission of a focused ultrasound field. In the simulations the relative standard deviation of the velocity magnitude is between 0.7% and 7.7% for flow angles between 45 deg and 90 deg. The study showed that angle estimation by directional beamforming can be estimated...

Improved Modeling of Finite-Rate Turbulent Combustion Processes in Research Combustors

Science.gov (United States)

VanOverbeke, Thomas J.

1998-01-01

The objective of this thesis is to further develop and test a stochastic model of turbulent combustion in recirculating flows. There is a requirement to increase the accuracy of multi-dimensional combustion predictions. As turbulence affects reaction rates, this interaction must be more accurately evaluated. In this work a more physically correct way of handling the interaction of turbulence on combustion is further developed and tested. As turbulence involves randomness, stochastic modeling is used. Averaged values such as temperature and species concentration are found by integrating the probability density function (pdf) over the range of the scalar. The model in this work does not assume the pdf type, but solves for the evolution of the pdf using the Monte Carlo solution technique. The model is further developed by including a more robust reaction solver, by using accurate thermodynamics and by more accurate transport elements. The stochastic method is used with Semi-Implicit Method for Pressure-Linked Equations. The SIMPLE method is used to solve for velocity, pressure, turbulent kinetic energy and dissipation. The pdf solver solves for temperature and species concentration. Thus, the method is partially familiar to combustor engineers. The method is compared to benchmark experimental data and baseline calculations. The baseline method was tested on isothermal flows, evaporating sprays and combusting sprays. Pdf and baseline predictions were performed for three diffusion flames and one premixed flame. The pdf method predicted lower combustion rates than the baseline method in agreement with the data, except for the premixed flame. The baseline and stochastic predictions bounded the experimental data for the premixed flame. The use of a continuous mixing model or relax to mean mixing model had little effect on the prediction of average temperature. Two grids were used in a hydrogen diffusion flame simulation. Grid density did not effect the predictions except

A Method of Initial Velocity Measurement for Rocket Projectile

Directory of Open Access Journals (Sweden)

Zhang Jiancheng

2017-01-01

Full Text Available In this paper, a novel method is proposed to measure the initial velocity of the rocket based on STFT (the short-time Fourier transform and the WT (wavelet transform. The radar echo signal processing procedure involves the following steps: sampling process, overlapping windows, wavelet decomposition and reconstruction, computing FFT (Fast Fourier Transform and spectrum analysis, power spectrum peak detection. Then, according to the peak of the detection power spectrum, the corresponding Doppler frequency is obtained. Finally, on the basis of the relationship between Doppler frequency and instantaneous velocity, the V-T curve is drawn in MATLAB to obtain the initial velocity of the rocket muzzle.

Simulation of anisotropic diffusion by means of a diffusion velocity method

CERN Document Server

Beaudoin, A; Rivoalen, E

2003-01-01

An alternative method to the Particle Strength Exchange method for solving the advection-diffusion equation in the general case of a non-isotropic and non-uniform diffusion is proposed. This method is an extension of the diffusion velocity method. It is shown that this extension is quite straightforward due to the explicit use of the diffusion flux in the expression of the diffusion velocity. This approach is used to simulate pollutant transport in groundwater and the results are compared to those of the PSE method presented in an earlier study by Zimmermann et al.

Maximum Likelihood-Based Methods for Target Velocity Estimation with Distributed MIMO Radar

Directory of Open Access Journals (Sweden)

Zhenxin Cao

2018-02-01

Full Text Available The estimation problem for target velocity is addressed in this in the scenario with a distributed multi-input multi-out (MIMO radar system. A maximum likelihood (ML-based estimation method is derived with the knowledge of target position. Then, in the scenario without the knowledge of target position, an iterative method is proposed to estimate the target velocity by updating the position information iteratively. Moreover, the Carmér-Rao Lower Bounds (CRLBs for both scenarios are derived, and the performance degradation of velocity estimation without the position information is also expressed. Simulation results show that the proposed estimation methods can approach the CRLBs, and the velocity estimation performance can be further improved by increasing either the number of radar antennas or the information accuracy of the target position. Furthermore, compared with the existing methods, a better estimation performance can be achieved.

Modeling molecular mixing in a spatially inhomogeneous turbulent flow

Science.gov (United States)

Meyer, Daniel W.; Deb, Rajdeep

2012-02-01

Simulations of spatially inhomogeneous turbulent mixing in decaying grid turbulence with a joint velocity-concentration probability density function (PDF) method were conducted. The inert mixing scenario involves three streams with different compositions. The mixing model of Meyer ["A new particle interaction mixing model for turbulent dispersion and turbulent reactive flows," Phys. Fluids 22(3), 035103 (2010)], the interaction by exchange with the mean (IEM) model and its velocity-conditional variant, i.e., the IECM model, were applied. For reference, the direct numerical simulation data provided by Sawford and de Bruyn Kops ["Direct numerical simulation and lagrangian modeling of joint scalar statistics in ternary mixing," Phys. Fluids 20(9), 095106 (2008)] was used. It was found that velocity conditioning is essential to obtain accurate concentration PDF predictions. Moreover, the model of Meyer provides significantly better results compared to the IECM model at comparable computational expense.

Multiplicative Process in Turbulent Velocity Statistics: A Simplified Analysis

Science.gov (United States)

Chillà, F.; Peinke, J.; Castaing, B.

1996-04-01

A lot of models in turbulence links the energy cascade process and intermittency, the characteristic of which being the shape evolution of the probability density functions (pdf) for longitudinal velocity increments. Using recent models and experimental results, we show that the flatness factor of these pdf gives a simple and direct estimate for what is called the deepness of the cascade. We analyse in this way the published data of a Direct Numerical Simulation and show that the deepness of the cascade presents the same Reynolds number dependence as in laboratory experiments. Plusieurs modèles de turbulence relient la cascade d'énergie et l'intermittence, caractérisée par l'évolution des densités de probabilité (pdf) des incréments longitudinaux de vitesse. Nous appuyant aussi bien sur des modèles récents que sur des résultats expérimentaux, nous montrons que la Curtosis de ces pdf permet une estimation simple et directe de la profondeur de la cascade. Cela nous permet de réanalyser les résultats publiés d'une simulation numérique et de montrer que la profondeur de la cascade y évolue de la même façon que pour les expériences de laboratoire en fonction du nombre de Reynolds.

Development of three-dimensional individual bubble-velocity measurement method by bubble tracking

International Nuclear Information System (INIS)

Kanai, Taizo; Furuya, Masahiro; Arai, Takahiro; Shirakawa, Kenetsu; Nishi, Yoshihisa

2012-01-01

A gas-liquid two-phase flow in a large diameter pipe exhibits a three-dimensional flow structure. Wire-Mesh Sensor (WMS) consists of a pair of parallel wire layers located at the cross section of a pipe. Both the parallel wires cross at 90o with a small gap and each intersection acts as an electrode. The WMS allows the measurement of the instantaneous two-dimensional void-fraction distribution over the cross-section of a pipe, based on the difference between the local instantaneous conductivity of the two-phase flow. Furthermore, the WMS can acquire a phasic-velocity on the basis of the time lag of void signals between two sets of WMS. Previously, the acquired phasic velocity was one-dimensional with time-averaged distributions. The authors propose a method to estimate the three-dimensional bubble-velocity individually WMS data. The bubble velocity is determined by the tracing method. In this tracing method, each bubble is separated from WMS signal, volume and center coordinates of the bubble is acquired. Two bubbles with near volume at two WMS are considered as the same bubble and bubble velocity is estimated from the displacement of the center coordinates of the two bubbles. The validity of this method is verified by a swirl flow. The proposed method can successfully visualize a swirl flow structure and the results of this method agree with the results of cross-correlation analysis. (author)

Probing Amorphous Components in High Temperature TE Materials by in situ Total Scattering and the Pair Distribution Function (PDF) Method

DEFF Research Database (Denmark)

Reardon, Hazel; Iversen, Bo Brummerstedt; Blichfeld, Anders Bank

-I clathrate Ba8Ga16Ge30. This suggests that local structure reorientations in the cage are likely to be the root cause of the degradation of the structure. This deepens our understanding of disordered clathrates, and provides evidence that the PDF technique is an effective method for probing local structure.......e., by measuring both the Bragg and diffuse scattering from a sample. This method has rarely been exploited by the non-oxide thermoelectrics community. , , Treating total scattering data by the Pair Distribution Function method is a logical approach to understanding defects, disorder and amorphous components...... to heating cycles, then we are closer to distinguishing how we may generate materials that do not undergo specific structure reorientation processes, and/or how we may mitigate them before they occur. Here, we will present a total scattering and PDF study that probes the local structure of the Type...

The gamma-ray-flux PDF from galactic halo substructure

International Nuclear Information System (INIS)

Lee, Samuel K.; Ando, Shin'ichiro; Kamionkowski, Marc

2009-01-01

One of the targets of the recently launched Fermi Gamma-ray Space Telescope is a diffuse gamma-ray background from dark-matter annihilation or decay in the Galactic halo. N-body simulations and theoretical arguments suggest that the dark matter in the Galactic halo may be clumped into substructure, rather than smoothly distributed. Here we propose the gamma-ray-flux probability distribution function (PDF) as a probe of substructure in the Galactic halo. We calculate this PDF for a phenomenological model of halo substructure and determine the regions of the substructure parameter space in which the PDF may be distinguished from the PDF for a smooth distribution of dark matter. In principle, the PDF allows a statistical detection of substructure, even if individual halos cannot be detected. It may also allow detection of substructure on the smallest microhalo mass scales, ∼ M ⊕ , for weakly-interacting massive particles (WIMPs). Furthermore, it may also provide a method to measure the substructure mass function. However, an analysis that assumes a typical halo substructure model and a conservative estimate of the diffuse background suggests that the substructure PDF may not be detectable in the lifespan of Fermi in the specific case that the WIMP is a neutralino. Nevertheless, for a large range of substructure, WIMP annihilation, and diffuse background models, PDF analysis may provide a clear signature of substructure

Minimizers with discontinuous velocities for the electromagnetic variational method

International Nuclear Information System (INIS)

De Luca, Jayme

2010-01-01

The electromagnetic two-body problem has neutral differential delay equations of motion that, for generic boundary data, can have solutions with discontinuous derivatives. If one wants to use these neutral differential delay equations with arbitrary boundary data, solutions with discontinuous derivatives must be expected and allowed. Surprisingly, Wheeler-Feynman electrodynamics has a boundary value variational method for which minimizer trajectories with discontinuous derivatives are also expected, as we show here. The variational method defines continuous trajectories with piecewise defined velocities and accelerations, and electromagnetic fields defined by the Euler-Lagrange equations on trajectory points. Here we use the piecewise defined minimizers with the Lienard-Wierchert formulas to define generalized electromagnetic fields almost everywhere (but on sets of points of zero measure where the advanced/retarded velocities and/or accelerations are discontinuous). Along with this generalization we formulate the generalized absorber hypothesis that the far fields vanish asymptotically almost everywhere and show that localized orbits with far fields vanishing almost everywhere must have discontinuous velocities on sewing chains of breaking points. We give the general solution for localized orbits with vanishing far fields by solving a (linear) neutral differential delay equation for these far fields. We discuss the physics of orbits with discontinuous derivatives stressing the differences to the variational methods of classical mechanics and the existence of a spinorial four-current associated with the generalized variational electrodynamics.

Sound Velocity in Soap Foams

International Nuclear Information System (INIS)

Wu Gong-Tao; Lü Yong-Jun; Liu Peng-Fei; Li Yi-Ning; Shi Qing-Fan

2012-01-01

The velocity of sound in soap foams at high gas volume fractions is experimentally studied by using the time difference method. It is found that the sound velocities increase with increasing bubble diameter, and asymptotically approach to the value in air when the diameter is larger than 12.5 mm. We propose a simple theoretical model for the sound propagation in a disordered foam. In this model, the attenuation of a sound wave due to the scattering of the bubble wall is equivalently described as the effect of an additional length. This simplicity reasonably reproduces the sound velocity in foams and the predicted results are in good agreement with the experiments. Further measurements indicate that the increase of frequency markedly slows down the sound velocity, whereas the latter does not display a strong dependence on the solution concentration

A Lagrangian mixing frequency model for transported PDF modeling

Science.gov (United States)

Turkeri, Hasret; Zhao, Xinyu

2017-11-01

In this study, a Lagrangian mixing frequency model is proposed for molecular mixing models within the framework of transported probability density function (PDF) methods. The model is based on the dissipations of mixture fraction and progress variables obtained from Lagrangian particles in PDF methods. The new model is proposed as a remedy to the difficulty in choosing the optimal model constant parameters when using conventional mixing frequency models. The model is implemented in combination with the Interaction by exchange with the mean (IEM) mixing model. The performance of the new model is examined by performing simulations of Sandia Flame D and the turbulent premixed flame from the Cambridge stratified flame series. The simulations are performed using the pdfFOAM solver which is a LES/PDF solver developed entirely in OpenFOAM. A 16-species reduced mechanism is used to represent methane/air combustion, and in situ adaptive tabulation is employed to accelerate the finite-rate chemistry calculations. The results are compared with experimental measurements as well as with the results obtained using conventional mixing frequency models. Dynamic mixing frequencies are predicted using the new model without solving additional transport equations, and good agreement with experimental data is observed.

Burning velocity measurements of nitrogen-containing compounds.

Science.gov (United States)

Takizawa, Kenji; Takahashi, Akifumi; Tokuhashi, Kazuaki; Kondo, Shigeo; Sekiya, Akira

2008-06-30

Burning velocity measurements of nitrogen-containing compounds, i.e., ammonia (NH3), methylamine (CH3NH2), ethylamine (C2H5NH2), and propylamine (C3H7NH2), were carried out to assess the flammability of potential natural refrigerants. The spherical-vessel (SV) method was used to measure the burning velocity over a wide range of sample and air concentrations. In addition, flame propagation was directly observed by the schlieren photography method, which showed that the spherical flame model was applicable to flames with a burning velocity higher than approximately 5 cm s(-1). For CH3NH2, the nozzle burner method was also used to confirm the validity of the results obtained by closed vessel methods. We obtained maximum burning velocities (Su0,max) of 7.2, 24.7, 26.9, and 28.3 cm s(-1) for NH3, CH3NH2, C2H5NH2, and C3H7NH2, respectively. It was noted that the burning velocities of NH3 and CH3NH2 were as high as those of the typical hydrofluorocarbon refrigerants difluoromethane (HFC-32, Su0,max=6.7 cm s(-1)) and 1,1-difluoroethane (HFC-152a, Su0,max=23.6 cm s(-1)), respectively. The burning velocities were compared with those of the parent alkanes, and it was found that introducing an NH2 group into hydrocarbon molecules decreases their burning velocity.

Probability density function method for variable-density pressure-gradient-driven turbulence and mixing

International Nuclear Information System (INIS)

Bakosi, Jozsef; Ristorcelli, Raymond J.

2010-01-01

Probability density function (PDF) methods are extended to variable-density pressure-gradient-driven turbulence. We apply the new method to compute the joint PDF of density and velocity in a non-premixed binary mixture of different-density molecularly mixing fluids under gravity. The full time-evolution of the joint PDF is captured in the highly non-equilibrium flow: starting from a quiescent state, transitioning to fully developed turbulence and finally dissipated by molecular diffusion. High-Atwood-number effects (as distinguished from the Boussinesq case) are accounted for: both hydrodynamic turbulence and material mixing are treated at arbitrary density ratios, with the specific volume, mass flux and all their correlations in closed form. An extension of the generalized Langevin model, originally developed for the Lagrangian fluid particle velocity in constant-density shear-driven turbulence, is constructed for variable-density pressure-gradient-driven flows. The persistent small-scale anisotropy, a fundamentally 'non-Kolmogorovian' feature of flows under external acceleration forces, is captured by a tensorial diffusion term based on the external body force. The material mixing model for the fluid density, an active scalar, is developed based on the beta distribution. The beta-PDF is shown to be capable of capturing the mixing asymmetry and that it can accurately represent the density through transition, in fully developed turbulence and in the decay process. The joint model for hydrodynamics and active material mixing yields a time-accurate evolution of the turbulent kinetic energy and Reynolds stress anisotropy without resorting to gradient diffusion hypotheses, and represents the mixing state by the density PDF itself, eliminating the need for dubious mixing measures. Direct numerical simulations of the homogeneous Rayleigh-Taylor instability are used for model validation.

PDF approach for turbulent scalar field: Some recent developments

Science.gov (United States)

Gao, Feng

1993-01-01

The probability density function (PDF) method has been proven a very useful approach in turbulence research. It has been particularly effective in simulating turbulent reacting flows and in studying some detailed statistical properties generated by a turbulent field There are, however, some important questions that have yet to be answered in PDF studies. Our efforts in the past year have been focused on two areas. First, a simple mixing model suitable for Monte Carlo simulations has been developed based on the mapping closure. Secondly, the mechanism of turbulent transport has been analyzed in order to understand the recently observed abnormal PDF's of turbulent temperature fields generated by linear heat sources.

Velocity and concentration fields in turbulent buoyant mixing in tilted tubes

Science.gov (United States)

Znaien, J.; Moisy, F.; Hulin, J. P.; Salin, D.; Hinch, E. J.

2008-11-01

2D PIV and LIF measurements have been performed on buoyancy driven flows of two miscible fluids of the same viscosity in a tube tilted at different angles θ from vertical and at different density contrasts (characterized by the Atwood number At). As θ increases and At decreases, the flow regime evolves, behind the front, from a turbulent shear flow towards a laminar counter flow with 3 layers of different concentrations. Time variations of the structure function show that both intermittent and developed turbulence occur in intermediate conditions. In the turbulent regime (Reλ˜60) the magnitudes of the longitudinal u'^2 and transverse v'^2 velocity fluctuations and of the component u'v' of the Reynolds stress tensor are shown to be largest on the tube axis while viscous stresses is only important close to the walls. The analyzis of the momentum transfer in the flow with buoyancy forces estimated from the concentration gradients demonstrates that 3D effects are required to achieve the momentum balance. These results are discussed in the framework of classical turbulence models.

Adobe Acrobat X PDF Bible

CERN Document Server

Padova, Ted

2011-01-01

The classic Acrobat and PDF reference, updated to cover the latest release. Consistently the most authoritative and comprehensive resource on Acrobat and PDF format, this standard reference returns with in-depth coverage of the newest version of Acrobat. Written by bestselling author Ted Padova, this book is packed with real-world insights and techniques gained from Padova's daily use of Acrobat and PDF under deadline constraints. You'll discover everything there is to know about using Acrobat and PDF for print prepress, the Internet, CD-ROMs, and other forms of media.: Popular author Ted Pado

Muscle conduction velocity, surface electromyography variables, and echo intensity during concentric and eccentric fatigue.

Science.gov (United States)

Gonzalez-Izal, Miriam; Lusa Cadore, Eduardo; Izquierdo, Mikel

2014-03-01

Concentric (CON) and eccentric (ECC) contractions may involve different mechanisms related to changes in sarcolemma status and the consequent alteration of action potential transmission along muscle fibers. Muscle conduction velocity (CV), surface electromyography signal (sEMG), muscle quality, and blood lactate concentrations were analyzed during CON and ECC actions. Compared with ECC, the CON protocol resulted in greater muscle force losses, blood lactate concentrations, and changes in sEMG parameters. Similar reductions in CV were detected in both protocols. Higher echo intensity values were observed 2 days after ECC due to greater muscle damage. The effects of the muscle damage produced by ECC exercise on the transmission of action potentials along muscle fibers (measured as the CV) may be comparable with the effects of hydrogen accumulation produced by CON exercise (related to greater lactate concentrations), which causes greater force loss and change in other sEMG variables during CON than during ECC actions.

Development of a high velocity rain erosion test method

Energy Technology Data Exchange (ETDEWEB)

Chung, Dong Teak; Jin, Doo Han [Korea University of Technology and Education, Cheonan (Korea, Republic of); Kang, Hyung [Agency for Defense Development, Daejeon (Korea, Republic of)

2009-07-01

The nose of a missile, flying through raining region with a supersonic speed, is subjected to the rain erosion because the nose is made of a brittle ceramic material. A simple yet very effective rain erosion test method is developed. The sabot assembly similar to the hypodermic syringe carries specific amount of water is launched by a low pressure air gun. After the stopper stop the sabot assembly by impact, the steel plunger continues moving toward to squeeze the silicon rubber in front. The pressurized silicon rubber then is squeezed through the orifice in front of the sabot at high velocity, thus, accelerates the water droplet to higher velocity. The droplet velocity up to 800m/s is successfully attained using a low pressure air gun. The ceramic specimen assembly is placed in front of the high speed water droplet and the rain erosion damage on the surface of the specimen is observed.

High accuracy velocity control method for the french moving-coil watt balance

International Nuclear Information System (INIS)

Topcu, Suat; Chassagne, Luc; Haddad, Darine; Alayli, Yasser; Juncar, Patrick

2004-01-01

We describe a novel method of velocity control dedicated to the French moving-coil watt balance. In this project, a coil has to move in a magnetic field at a velocity of 2 mm s -1 with a relative uncertainty of 10 -9 over 60 mm. Our method is based on the use of both a heterodyne Michelson's interferometer, a two-level translation stage, and a homemade high frequency phase-shifting electronic circuit. To quantify the stability of the velocity, the output of the interferometer is sent into a frequency counter and the Doppler frequency shift is recorded. The Allan standard deviation has been used to calculate the stability and a σ y (τ) of about 2.2x10 -9 over 400 s has been obtained

Dynamic Obstacle Avoidance for Unmanned Underwater Vehicles Based on an Improved Velocity Obstacle Method

Directory of Open Access Journals (Sweden)

Wei Zhang

2017-11-01

Full Text Available In view of a dynamic obstacle environment with motion uncertainty, we present a dynamic collision avoidance method based on the collision risk assessment and improved velocity obstacle method. First, through the fusion optimization of forward-looking sonar data, the redundancy of the data is reduced and the position, size and velocity information of the obstacles are obtained, which can provide an accurate decision-making basis for next-step collision avoidance. Second, according to minimum meeting time and the minimum distance between the obstacle and unmanned underwater vehicle (UUV, this paper establishes the collision risk assessment model, and screens key obstacles to avoid collision. Finally, the optimization objective function is established based on the improved velocity obstacle method, and a UUV motion characteristic is used to calculate the reachable velocity sets. The optimal collision speed of UUV is searched in velocity space. The corresponding heading and speed commands are calculated, and outputted to the motion control module. The above is the complete dynamic obstacle avoidance process. The simulation results show that the proposed method can obtain a better collision avoidance effect in the dynamic environment, and has good adaptability to the unknown dynamic environment.

Dense velocity reconstruction from tomographic PTV with material derivatives

Science.gov (United States)

Schneiders, Jan F. G.; Scarano, Fulvio

2016-09-01

A method is proposed to reconstruct the instantaneous velocity field from time-resolved volumetric particle tracking velocimetry (PTV, e.g., 3D-PTV, tomographic PTV and Shake-the-Box), employing both the instantaneous velocity and the velocity material derivative of the sparse tracer particles. The constraint to the measured temporal derivative of the PTV particle tracks improves the consistency of the reconstructed velocity field. The method is christened as pouring time into space, as it leverages temporal information to increase the spatial resolution of volumetric PTV measurements. This approach becomes relevant in cases where the spatial resolution is limited by the seeding concentration. The method solves an optimization problem to find the vorticity and velocity fields that minimize a cost function, which includes next to instantaneous velocity, also the velocity material derivative. The velocity and its material derivative are related through the vorticity transport equation, and the cost function is minimized using the limited-memory Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) algorithm. The procedure is assessed numerically with a simulated PTV experiment in a turbulent boundary layer from a direct numerical simulation (DNS). The experimental validation considers a tomographic particle image velocimetry (PIV) experiment in a similar turbulent boundary layer and the additional case of a jet flow. The proposed technique (`vortex-in-cell plus', VIC+) is compared to tomographic PIV analysis (3D iterative cross-correlation), PTV interpolation methods (linear and adaptive Gaussian windowing) and to vortex-in-cell (VIC) interpolation without the material derivative. A visible increase in resolved details in the turbulent structures is obtained with the VIC+ approach, both in numerical simulations and experiments. This results in a more accurate determination of the turbulent stresses distribution in turbulent boundary layer investigations. Data from a jet

Method of LSD profile asymmetry for estimating the center of mass velocities of pulsating stars

Science.gov (United States)

Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Cacciari, C.; Clementini, C.

2016-05-01

We present radial velocity analysis for 20 solar neighborhood RR Lyrae and 3 Population II Cepheids. High-resolution spectra were observed with either TNG/SARG or VLT/UVES over varying phases. To estimate the center of mass (barycentric) velocities of the program stars, we utilized two independent methods. First, the 'classic' method was employed, which is based on RR Lyrae radial velocity curve templates. Second, we provide the new method that used absorption line profile asymmetry to determine both the pulsation and the barycentric velocities even with a low number of high-resolution spectra and in cases where the phase of the observations is uncertain. This new method is based on a least squares deconvolution (LSD) of the line profiles in order to an- alyze line asymmetry that occurs in the spectra of pulsating stars. By applying this method to our sample stars we attain accurate measurements (+- 2 kms^-1) of the pulsation component of the radial velocity. This results in determination of the barycentric velocity to within 5 kms^-1 even with a low number of high- resolution spectra. A detailed investigation of LSD profile asymmetry shows the variable nature of the project factor at different pulsation phases, which should be taken into account in the detailed spectroscopic analysis of pulsating stars.

Modeling the Impacts of Suspended Sediment Concentration and Current Velocity on Submersed Vegetation in an Illinois River Pool, USA

National Research Council Canada - National Science Library

Best, Elly

2004-01-01

This technical note uses a modeling approach to examine the impacts of suspended sediment concentrations and current velocity on the persistence of submersed macrophytes in a shallow aquatic system...

Comparison of Large Eddy Simulations and κ-ε Modelling of Fluid Velocity and Tracer Concentration in Impinging Jet Mixers

Directory of Open Access Journals (Sweden)

Wojtas Krzysztof

2015-06-01

Full Text Available Simulations of turbulent mixing in two types of jet mixers were carried out using two CFD models, large eddy simulation and κ-ε model. Modelling approaches were compared with experimental data obtained by the application of particle image velocimetry and planar laser-induced fluorescence methods. Measured local microstructures of fluid velocity and inert tracer concentration can be used for direct validation of numerical simulations. Presented results show that for higher tested values of jet Reynolds number both models are in good agreement with the experiments. Differences between models were observed for lower Reynolds numbers when the effects of large scale inhomogeneity are important.

Self-consistent EXAFS PDF Projection Method by Matched Correction of Fourier Filter Signal Distortion

International Nuclear Information System (INIS)

Lee, Jay Min; Yang, Dong-Seok

2007-01-01

Inverse problem solving computation was performed for solving PDF (pair distribution function) from simulated data EXAFS based on data FEFF. For a realistic comparison with experimental data, we chose a model of the first sub-shell Mn-0 pair showing the Jahn Teller distortion in crystalline LaMnO3. To restore the Fourier filtering signal distortion, involved in the first sub-shell information isolated from higher shell contents, relevant distortion matching function was computed initially from the proximity model, and iteratively from the prior-guess during consecutive regularization computation. Adaptive computation of EXAFS background correction is an issue of algorithm development, but our preliminary test was performed under the simulated background correction perfectly excluding the higher shell interference. In our numerical result, efficient convergence of iterative solution indicates a self-consistent tendency that a true PDF solution is convinced as a counterpart of genuine chi-data, provided that a background correction function is iteratively solved using an extended algorithm of MEPP (Matched EXAFS PDF Projection) under development

Water erosion in surface soil conditions: runoff velocity, concentration and D50 index of sediments in runoff

OpenAIRE

Ramos,Júlio César; Bertol,Ildegardis; Barbosa,Fabrício Tondello; Bertól,Camilo; Mafra,Álvaro Luiz; Miquelluti,David José; Mecabô Júnior,José

2016-01-01

ABSTRACT Water erosion and contamination of water resources are influenced by concentration and diameter of sediments in runoff. This study aimed to quantify runoff velocity and concentration and the D50 index of sediments in runoff under different soil surface managements, in the following treatments: i) cropped systems: no-tilled soil covered by ryegrass (Lolium multiflorum Lam.) residue, with high soil cover and minimal roughness (HCR); no tilled soil covered by vetch (Vicia sativa L.) res...

A multi-time-step noise reduction method for measuring velocity statistics from particle tracking velocimetry

Science.gov (United States)

Machicoane, Nathanaël; López-Caballero, Miguel; Bourgoin, Mickael; Aliseda, Alberto; Volk, Romain

2017-10-01

We present a method to improve the accuracy of velocity measurements for fluid flow or particles immersed in it, based on a multi-time-step approach that allows for cancellation of noise in the velocity measurements. Improved velocity statistics, a critical element in turbulent flow measurements, can be computed from the combination of the velocity moments computed using standard particle tracking velocimetry (PTV) or particle image velocimetry (PIV) techniques for data sets that have been collected over different values of time intervals between images. This method produces Eulerian velocity fields and Lagrangian velocity statistics with much lower noise levels compared to standard PIV or PTV measurements, without the need of filtering and/or windowing. Particle displacement between two frames is computed for multiple different time-step values between frames in a canonical experiment of homogeneous isotropic turbulence. The second order velocity structure function of the flow is computed with the new method and compared to results from traditional measurement techniques in the literature. Increased accuracy is also demonstrated by comparing the dissipation rate of turbulent kinetic energy measured from this function against previously validated measurements.

621.pdf | Pdf2006Oct | sadha-na | Indian Academy of Sciences

Indian Academy of Sciences (India)

Home; sadha-na; Pdf2006Oct; 621.pdf. 404! error. The page your are looking for can not be found! Please check the link or use the navigation bar at the top. YouTube; Twitter; Facebook; Blog. Academy News. IAS Logo. 29th Mid-year meeting. Posted on 19 January 2018. The 29th Mid-year meeting of the Academy will be ...

No relationship between cerebral blood flow velocity and cerebrovascular reserve capacity and contemporaneously measured glucose and insulin concentrations in diabetes mellitus

NARCIS (Netherlands)

Fülesdi, B.; Limburg, M.; Bereczki, D.; Molnár, C.; Michels, R. P.; Leányvári, Z.; Csiba, L.

1999-01-01

Blood glucose and insulin concentrations have been reported to influence cerebral hemodynamics. We studied the relationship between actual blood glucose and insulin concentrations and resting cerebral blood flow velocity in the middle cerebral artery and cerebrovascular reserve capacity after

Procedures, analysis, and comparison of groundwater velocity measurement methods for unconfined aquifers

International Nuclear Information System (INIS)

Kearl, P.M.; Dexter, J.J.; Price, J.E.

1988-09-01

Six methods for determining the average linear velocity of ground- water were tested at two separate field sites. The methods tested include bail tests, pumping tests, wave propagation, tracer tests, Geoflo Meter/reg sign/, and borehole dilution. This report presents procedures for performing field tests and compares the results of each method on the basis of application, cost, and accuracy. Comparisons of methods to determine the ground-water velocity at two field sites show certain methods yield similar results while other methods measure significantly different values. The literature clearly supports the reliability of pumping tests for determining hydraulic conductivity. Results of this investigation support this finding. Pumping tests, however, are limited because they measure an average hydraulic conductivity which is only representative of the aquifer within the radius of influence. Bail tests are easy and inexpensive to perform. If the tests are conducted on the majority of wells at a hazardous waste site, then the heterogeneity of the site aquifer can be assessed. However, comparisons of bail-test results with pumping-test and tracer-test results indicate that the accuracy of the method is questionable. Consequently, the principal recommendation of this investigation, based on cost and reliability of the ground-water velocity measurement methods, is that bail tests should be performed on all or a majority of monitoring wells at a site to determine the ''relative'' hydraulic conductivities

Comparison of shear-wave velocity measurements by crosshole, downhole and seismic cone penetration test methods

Energy Technology Data Exchange (ETDEWEB)

Suthaker, N.; Tweedie, R. [Thurber Engineering Ltd., Edmonton, AB (Canada)

2009-07-01

Shear wave velocity measurements are an integral part of geotechnical studies for major structures and are an important tool in their design for site specific conditions such as site-specific earthquake response. This paper reported on a study in which shear wave velocities were measured at a proposed petrochemical plant site near Edmonton, Alberta. The proposed site is underlain by lacustrine clay, glacial till and upper Cretaceous clay shale and sandstone bedrock. The most commonly used methods for determining shear wave velocity include crosshole seismic tests, downhole seismic tests, and seismic cone penetration tests (SCPT). This paper presented the results of all 3 methods used in this study and provided a comparison of the various test methods and their limitations. The crosshole test results demonstrated a common trend of increasing shear wave velocity with depth to about 15 m, below which the velocities remained relatively constant. An anomaly was noted at one site, where the shear wave velocity was reduced at a zone corresponding to clay till containing stiff high plastic clay layers. The field study demonstrated that reasonable agreement in shear wave velocity measurements can be made using crosshole, downhole and seismic tests in the same soil conditions. The National Building Code states that the shear wave velocity is the fundamental method for determining site classification, thus emphasizing the importance of obtaining shear wave velocity measurements for site classification. It was concluded that an SCPT program can be incorporated into the field program without much increase in cost and can be supplemented by downhole or crosshole techniques. 5 refs., 2 tabs., 10 figs.

Inversion methods for fast-ion velocity-space tomography in fusion plasmas

DEFF Research Database (Denmark)

Jacobsen, Asger Schou; Stagner, L.; Salewski, Mirko

2016-01-01

Velocity-space tomography has been used to infer 2D fast-ion velocity distribution functions. Here we compare the performance of five different tomographic inversion methods: truncated singular value decomposition, maximum entropy, minimum Fisher information and zeroth and first-order Tikhonov...... regularization. The inversion methods are applied to fast-ion Dα measurements taken just before and just after a sawtooth crash in the ASDEX Upgrade tokamak as well as to synthetic measurements from different test distributions. We find that the methods regularizing by penalizing steep gradients or maximizing...... entropy perform best. We assess the uncertainty of the calculated inversions taking into account photon noise, uncertainties in the forward model as well as uncertainties introduced by the regularization which allows us to distinguish regions of high and low confidence in the tomographies. In high...

Hot-Wire Calibration at Low Velocities: Revisiting the Vortex Shedding Method

Directory of Open Access Journals (Sweden)

Sohrab S. Sattarzadeh

2013-01-01

Full Text Available The necessity to calibrate hot-wire probes against a known velocity causes problems at low velocities, due to the inherent inaccuracy of pressure transducers at low differential pressures. The vortex shedding calibration method is in this respect a recommended technique to obtain calibration data at low velocities, due to its simplicity and accuracy. However, it has mainly been applied in a low and narrow Reynolds number range known as the laminar vortex shedding regime. Here, on the other hand, we propose to utilize the irregular vortex shedding regime and show where the probe needs to be placed with respect to the cylinder in order to obtain unambiguous calibration data.

Transported PDF Modeling of Nonpremixed Turbulent CO/H-2/N-2 Jet Flames

Energy Technology Data Exchange (ETDEWEB)

Zhao, xinyu; Haworth, D. C.; Huckaby, E. David

2012-01-01

Turbulent CO/H{sub 2}/N{sub 2} (“syngas”) flames are simulated using a transported composition probability density function (PDF) method. A consistent hybrid Lagrangian particle/Eulerian mesh algorithm is used to solve the modeled PDF transport equation. The model includes standard k–ϵ turbulence, gradient transport for scalars, and Euclidean minimum spanning tree (EMST) mixing. Sensitivities of model results to variations in the turbulence model, the treatment of radiation heat transfer, the choice of chemical mechanism, and the PDF mixing model are explored. A baseline model reproduces the measured mean and rms temperature, major species, and minor species profiles reasonably well, and captures the scaling that is observed in the experiments. Both our results and the literature suggest that further improvements can be realized with adjustments in the turbulence model, the radiation heat transfer model, and the chemical mechanism. Although radiation effects are relatively small in these flames, consideration of radiation is important for accurate NO prediction. Chemical mechanisms that have been developed specifically for fuels with high concentrations of CO and H{sub 2} perform better than a methane mechanism that was not designed for this purpose. It is important to account explicitly for turbulence–chemistry interactions, although the details of the mixing model do not make a large difference in the results, within reasonable limits.

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African Journals Online (AJOL)

2009-09-19

included questions on number of years in practice, number of patients seen per day and the type of practice. knowledge ... paeditricians and other health professionals who work with children. Primary preventive strategies for ..... fammed.musc.edu/fmc/data/pdf/ fmcrfinal/specialtopics.pdf. Accessed. September 19, 2009. 21.

A Comparative Study of PDF Generation Methods: Measuring Loss of Fidelity When Converting Arabic and Persian MS Word Files to PDF

Science.gov (United States)

2011-02-17

document objects, on one or more electronic document pages. These commands have their roots in typography , so, to understand the PDF Language, one...must have at least a rudimentary understanding of typography . Only a few of the typographic commands, called text showing operators, can hold strings

Method of measuring directed electron velocities in flowing plasma using the incoherent regions of laser scattering

International Nuclear Information System (INIS)

Jacoby, B.A.; York, T.M.

1979-02-01

With the presumption that a shifted Maxwellian velocity distribution adequately describes the electrons in a flowing plasma, the details of a method to measure their directed velocity are described. The system consists of a ruby laser source and two detectors set 180 0 from each other and both set at 90 0 with respect to the incident laser beam. The lowest velocity that can be determined by this method depends on the electron thermal velocity. The application of this diagnostic to the measurement of flow velocities in plasma being lost from the ends of theta-pinch devices is described

Estimation of suspended sediment concentration in rivers using acoustic methods.

Science.gov (United States)

Elçi, Sebnem; Aydin, Ramazan; Work, Paul A

2009-12-01

Acoustic Doppler current meters (ADV, ADCP, and ADP) are widely used in water systems to measure flow velocities and velocity profiles. Although these meters are designed for flow velocity measurements, they can also provide information defining the quantity of particulate matter in the water, after appropriate calibration. When an acoustic instrument is calibrated for a water system, no additional sensor is needed to measure suspended sediment concentration (SSC). This provides the simultaneous measurements of velocity and concentration required for most sediment transport studies. The performance of acoustic Doppler current meters for measuring SSC was investigated in different studies where signal-to-noise ratio (SNR) and suspended sediment concentration were related using different formulations. However, these studies were each limited to a single study site where neither the effect of particle size nor the effect of temperature was investigated. In this study, different parameters that affect the performance of an ADV for the prediction of SSC are investigated. In order to investigate the reliability of an ADV for SSC measurements in different environments, flow and SSC measurements were made in different streams located in the Aegean region of Turkey having different soil types. Soil samples were collected from all measuring stations and particle size analysis was conducted by mechanical means. Multivariate analysis was utilized to investigate the effect of soil type and water temperature on the measurements. Statistical analysis indicates that SNR readings ob tained from the ADV are affected by water temperature and particle size distribution of the soil, as expected, and a prediction model is presented relating SNR readings to SSC mea surements where both water temperature and sediment characteristics type are incorporated into the model. The coefficients of the suggested model were obtained using the multivariate anal ysis. Effect of high turbidity

Two-stage open-loop velocity compensating method applied to multi-mass elastic transmission system

Directory of Open Access Journals (Sweden)

Zhang Deli

2014-02-01

Full Text Available In this paper, a novel vibration-suppression open-loop control method for multi-mass system is proposed, which uses two-stage velocity compensating algorithm and fuzzy I + P controller. This compensating method is based on model-based control theory in order to provide a damping effect on the system mechanical part. The mathematical model of multi-mass system is built and reduced to estimate the velocities of masses. The velocity difference between adjacent masses is calculated dynamically. A 3-mass system is regarded as the composition of two 2-mass systems in order to realize the two-stage compensating algorithm. Instead of using a typical PI controller in the velocity compensating loop, a fuzzy I + P controller is designed and its input variables are decided according to their impact on the system, which is different from the conventional fuzzy PID controller designing rules. Simulations and experimental results show that the proposed velocity compensating method is effective in suppressing vibration on a 3-mass system and it has a better performance when the designed fuzzy I + P controller is utilized in the control system.

Method for Estimating Evaporative Potential (IM/CLO) from ASTM Standard Single Wind Velocity Measures

Science.gov (United States)

2016-08-10

IM/CLO) FROM ASTM STANDARD SINGLE WIND VELOCITY MEASURES DISCLAIMER The opinions or assertions contained herein are the private views of the...USARIEM TECHNICAL REPORT T16-14 METHOD FOR ESTIMATING EVAPORATIVE POTENTIAL (IM/CLO) FROM ASTM STANDARD SINGLE WIND VELOCITY... ASTM STANDARD SINGLE WIND VELOCITY MEASURES Adam W. Potter Biophysics and Biomedical Modeling Division U.S. Army Research Institute of Environmental

On the peculiarities of LDA method in two-phase flows with high concentrations of particles

Science.gov (United States)

Poplavski, S. V.; Boiko, V. M.; Nesterov, A. U.

2016-10-01

Popular applications of laser Doppler anemometry (LDA) in gas dynamics are reviewed. It is shown that the most popular method cannot be used in supersonic flows and two-phase flows with high concentrations of particles. A new approach to implementation of the known LDA method based on direct spectral analysis, which offers better prospects for such problems, is presented. It is demonstrated that the method is suitable for gas-liquid jets. Owing to the progress in laser engineering, digital recording of spectra, and computer processing of data, the method is implemented at a higher technical level and provides new prospects of diagnostics of high-velocity dense two-phase flows.

A simple measurement method of molecular relaxation in a gas by reconstructing acoustic velocity dispersion

Science.gov (United States)

Zhu, Ming; Liu, Tingting; Zhang, Xiangqun; Li, Caiyun

2018-01-01

Recently, a decomposition method of acoustic relaxation absorption spectra was used to capture the entire molecular multimode relaxation process of gas. In this method, the acoustic attenuation and phase velocity were measured jointly based on the relaxation absorption spectra. However, fast and accurate measurements of the acoustic attenuation remain challenging. In this paper, we present a method of capturing the molecular relaxation process by only measuring acoustic velocity, without the necessity of obtaining acoustic absorption. The method is based on the fact that the frequency-dependent velocity dispersion of a multi-relaxation process in a gas is the serial connection of the dispersions of interior single-relaxation processes. Thus, one can capture the relaxation times and relaxation strengths of N decomposed single-relaxation dispersions to reconstruct the entire multi-relaxation dispersion using the measurements of acoustic velocity at 2N  +  1 frequencies. The reconstructed dispersion spectra are in good agreement with experimental data for various gases and mixtures. The simulations also demonstrate the robustness of our reconstructive method.

Concrete deterioration: detection by ultrasonic pulse velocity method

International Nuclear Information System (INIS)

Sutan, N.M.; Jaafar, M.S.; Hamdan, S.

2003-01-01

Tests were performed to evaluate the feasibility of using Ultrasonic Pulse Velocity Method (UPVM) in detecting defect and determining its depth during the early age concrete. Five reinforced concrete (RC) slabs of grade 30, 40 and 50 specimens at day 3, 7,14 and 28 with a fabricated void at a known location were used. The results obtained were compared to determine the accuracy of the method hence the effectiveness of the method with different strength and as the concrete matures. This method detects defects in specimens during the early age The accuracy varies with concrete strength and as the concrete mature. The test results indicate the method can be used to assess the in-situ properties of concrete or for quality control on site. The method showed better accuracy with stronger concrete detects defects with the accuracy ranging from 55.75-99.62% from day 3-28 (full strength) respectively. (author)

A new method of measuring centre-of-mass velocities of radially pulsating stars from high-resolution spectroscopy

Science.gov (United States)

Britavskiy, N.; Pancino, E.; Tsymbal, V.; Romano, D.; Fossati, L.

2018-03-01

We present a radial velocity analysis of 20 solar neighbourhood RR Lyrae and three Population II Cepheid variables. We obtained high-resolution, moderate-to-high signal-to-noise ratio spectra for most stars; these spectra covered different pulsation phases for each star. To estimate the gamma (centre-of-mass) velocities of the programme stars, we use two independent methods. The first, `classic' method is based on RR Lyrae radial velocity curve templates. The second method is based on the analysis of absorption-line profile asymmetry to determine both pulsational and gamma velocities. This second method is based on the least-squares deconvolution (LSD) technique applied to analyse the line asymmetry that occurs in the spectra. We obtain measurements of the pulsation component of the radial velocity with an accuracy of ±3.5 km s-1. The gamma velocity was determined with an accuracy of ±10 km s-1, even for those stars having a small number of spectra. The main advantage of this method is the possibility of obtaining an estimation of gamma velocity even from one spectroscopic observation with uncertain pulsation phase. A detailed investigation of LSD profile asymmetry shows that the projection factor p varies as a function of the pulsation phase - this is a key parameter, which converts observed spectral line radial velocity variations into photospheric pulsation velocities. As a by-product of our study, we present 41 densely spaced synthetic grids of LSD profile bisectors based on atmospheric models of RR Lyr covering all pulsation phases.

Diagnostic of N2(A) concentration in high velocity nitrogen afterglow at atmospheric pressure

Science.gov (United States)

Pointu, Anne-Marie; Mintusov, Evgeny

2009-10-01

An optical emission diagnostic was used to measure N2(A) concentration in a high velocity (1000 cm/s) N2 flowing afterglow of corona discharge at atmospheric pressure, used for biological decontamination. Introducing impurities of NO (measured at different axial distances and for different values of NO injected flow. Moreover, it has been demonstrated that N2(A) creation comes from N+N+N2 atom recombination with a global rate around 2e-33 cm^6/s, a result which agrees with literature, as well as N2(A) loss mechanisms were confirmed to go via quenching with O and N atoms. The order of magnitude of obtained N2(A) concentration, about 1e11 cm-3, coincides with the results of direct measurement (by Vegard-Kaplan band), using a spectrometer of better resolution.

Second sound velocities in superfluid 3He-4He solutions

International Nuclear Information System (INIS)

Dikina, L.S.; Kotenev, G.Ya.; Rudavskij, Eh.Ya.

1978-01-01

The velocities of the second sound in the superfluid He 3 -He 4 solutions were measured by the pulse method in the range of temperatures from 1.3 K to Tsub(lambda) and for He 3 concentrations up to 13%.The results obtained supplemented by those available before give the complete description of the concentration and temperature dependences of the second sound velocity in superfluid He 3 -He 4 solutions. The comprehensive comparison of the experimental data on the velocity of the second sound with the theoretical calculations for the superfluid solutions with arbitrary content of He 3 is performed. The good agreement is found between experiment and the theory. The experimental data obtained are used for determination of the potential, which determines the properties of the superfluid solutions

Effect of fluid velocity, temperature, and concentration of non-ionic surfactants on drag reduction

International Nuclear Information System (INIS)

Cho, Sung-Hwan; Tae, Choon-Seob; Zaheeruddin, M.

2007-01-01

The drag reduction (DR) and heat transfer efficiency reduction (ER) of non-ionic surfactant as a function of fluid velocity, temperature, and surfactant concentration were investigated. Several types of new surfactants, which contain amine-oxide and betaine, were developed. An experimental apparatus consisting of two temperature controlled water storage tanks, pumps, test specimen pipe and the piping network, two flow meters, two pressure gauges, a heat exchanger, and data logging system was built. From the experimental results, it was concluded that existing alkyl ammonium surfactant (CTAC; cethyl trimethyl ammonium chloride) had DR of 0.6-0.8 at 1000-2000 ppm concentration with fluid temperature ranging between 50 and 60 o C. However, the DR was very low when the fluid temperature was 70-80 o C. The new amine oxide and betaine surfactant (SAOB; stearyl amine oxide + betaine) had lower DR at fluid temperatures ranging between 50 and 60 o C compared with CTAC. However, with fluid temperature ranging between 70 and 80 o C the DR was 0.6-0.8 when the concentration level was between 1000 and 2000 ppm

Flow velocity measurement by using zero-crossing polarity cross correlation method

International Nuclear Information System (INIS)

Xu Chengji; Lu Jinming; Xia Hong

1993-01-01

Using the designed correlation metering system and a high accurate hot-wire anemometer as a calibration device, the experimental study of correlation method in a tunnel was carried out. The velocity measurement of gas flow by using zero-crossing polarity cross correlation method was realized and the experimental results has been analysed

Parallel ion flow velocity measurement using laser induced fluorescence method in an electron cyclotron resonance plasma

International Nuclear Information System (INIS)

Yoshimura, Shinji; Okamoto, Atsushi; Terasaka, Kenichiro; Ogiwara, Kohei; Tanaka, Masayoshi Y.; Aramaki, Mitsutoshi

2010-01-01

Parallel ion flow velocity along a magnetic field has been measured using a laser induced fluorescence (LIF) method in an electron cyclotron resonance (ECR) argon plasma with a weakly-diverging magnetic field. To measure parallel flow velocity in a cylindrical plasma using the LIF method, the laser beam should be injected along device axis; however, the reflection of the incident beam causes interference between the LIF emission of the incident and reflected beams. Here we present a method of quasi-parallel laser injection at a small angle, which utilizes the reflected beam as well as the incident beam to obtain the parallel ion flow velocity. Using this method, we observed an increase in parallel ion flow velocity along the magnetic field. The acceleration mechanism is briefly discussed on the basis of the ion fluid model. (author)

Factors influencing indoor concentrations of radon and daughter products

International Nuclear Information System (INIS)

Wang Hengde

1985-01-01

The correlation between indoor concentrations of 222 Rn and its daughters and some influencing factors is discussed and expressions of concentrations are derived with relation to radon exhalation rate from indoor surfaces, air exchange rate and daughter deposition velocities on indoor surfaces. Experimental methods for determining radon exhalation rate, air exchange rate and daughter deposition velocities are also mentioned

Construction update and drift velocity calibration for the CLAS drift chamber system

International Nuclear Information System (INIS)

Mestayer, M.D.; Barbosa, F.J.; Bonneau, P.; Burtin, E.; Christo, S.; Doolittle, G.; Dytman, S.A.; Gilfoyle, G.P.; Hyde-Wright, C.E.; Klein, A.; Kossov, M.V.; Kuhn, S.E.; Magahiz, R.; Miskimen, R.A.; Murphy, L.Y.; O'Meara, J.E.; Pyron, T.D.; Qin, L.; Raue, B.A.; Schumacher, R.A.; Tuzel, W.; Weinstein, L.B.; Yegneswaran, A.

1995-01-01

We briefly describe the drift chamber system for the CLAS detector at CEBAF, concentrating on the method which will be used to calibrate the drift velocity function. We identify key features of the function which should apply to any small-cell drift chamber geometry in which the cathode and anode surfaces are wires. Using these ideas, we describe a simple method to compensate for variations in the drift velocity function due to environmental changes. (orig.)

Construction update and drift velocity calibration for the CLAS drift chamber system

Energy Technology Data Exchange (ETDEWEB)

Mestayer, M.D. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Barbosa, F.J. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Bonneau, P. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Burtin, E. [University of South Carolina, Columbia, SC (United States); Christo, S. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Doolittle, G. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Dytman, S.A. [University of Pittsburg, Pittsburg, PA (United States); Gilfoyle, G.P. [University of Richmond, Richmond, VA (United States); Hyde-Wright, C.E. [Old Dominion University, Norfolk, VA (United States); Klein, A. [Old Dominion University, Norfolk, VA (United States); Kossov, M.V. [Christopher Newport University, Newport News, VA (United States); Kuhn, S.E. [Old Dominion University, Norfolk, VA (United States); Magahiz, R. [Carnegie-Mellon Univ., Pittsburgh, PA (United States); Miskimen, R.A. [University of Massachussetts, Amherst, MA (United States); Murphy, L.Y. [CE Saclay, Gif sur Yvette (France); O`Meara, J.E. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Pyron, T.D. [Old Dominion University, Norfolk, VA (United States); Qin, L. [Old Dominion University, Norfolk, VA (United States); Raue, B.A. [Old Dominion University, Norfolk, VA (United States); Schumacher, R.A. [Carnegie-Mellon Univ., Pittsburgh, PA (United States); Tuzel, W. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Weinstein, L.B. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States); Yegneswaran, A. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

1995-12-11

We briefly describe the drift chamber system for the CLAS detector at CEBAF, concentrating on the method which will be used to calibrate the drift velocity function. We identify key features of the function which should apply to any small-cell drift chamber geometry in which the cathode and anode surfaces are wires. Using these ideas, we describe a simple method to compensate for variations in the drift velocity function due to environmental changes. (orig.).

Analysis of antibody aggregate content at extremely high concentrations using sedimentation velocity with a novel interference optics.

Science.gov (United States)

Schilling, Kristian; Krause, Frank

2015-01-01

Monoclonal antibodies represent the most important group of protein-based biopharmaceuticals. During formulation, manufacturing, or storage, antibodies may suffer post-translational modifications altering their physical and chemical properties. Such induced conformational changes may lead to the formation of aggregates, which can not only reduce their efficiency but also be immunogenic. Therefore, it is essential to monitor the amount of size variants to ensure consistency and quality of pharmaceutical antibodies. In many cases, antibodies are formulated at very high concentrations > 50 g/L, mostly along with high amounts of sugar-based excipients. As a consequence, all routine aggregation analysis methods, such as size-exclusion chromatography, cannot monitor the size distribution at those original conditions, but only after dilution and usually under completely different solvent conditions. In contrast, sedimentation velocity (SV) allows to analyze samples directly in the product formulation, both with limited sample-matrix interactions and minimal dilution. One prerequisite for the analysis of highly concentrated samples is the detection of steep concentration gradients with sufficient resolution: Commercially available ultracentrifuges are not able to resolve such steep interference profiles. With the development of our Advanced Interference Detection Array (AIDA), it has become possible to register interferograms of solutions as highly concentrated as 150 g/L. The other major difficulty encountered at high protein concentrations is the pronounced non-ideal sedimentation behavior resulting from repulsive intermolecular interactions, for which a comprehensive theoretical modelling has not yet been achieved. Here, we report the first SV analysis of highly concentrated antibodies up to 147 g/L employing the unique AIDA ultracentrifuge. By developing a consistent experimental design and data fit approach, we were able to provide a reliable estimation of the minimum

Applying an economical scale-aware PDF-based turbulence closure model in NOAA NCEP GCMs.

Science.gov (United States)

Belochitski, A.; Krueger, S. K.; Moorthi, S.; Bogenschutz, P.; Cheng, A.

2017-12-01

A novel unified representation of sub-grid scale (SGS) turbulence, cloudiness, and shallow convection is being implemented into the NOAA NCEP Global Forecasting System (GFS) general circulation model. The approach, known as Simplified High Order Closure (SHOC), is based on predicting a joint PDF of SGS thermodynamic variables and vertical velocity, and using it to diagnose turbulent diffusion coefficients, SGS fluxes, condensation, and cloudiness. Unlike other similar methods, comparatively few new prognostic variables needs to be introduced, making the technique computationally efficient. In the base version of SHOC it is SGS turbulent kinetic energy (TKE), and in the developmental version — SGS TKE, and variances of total water and moist static energy (MSE). SHOC is now incorporated into a version of GFS that will become a part of the NOAA Next Generation Global Prediction System based around NOAA GFDL's FV3 dynamical core, NOAA Environmental Modeling System (NEMS) coupled modeling infrastructure software, and a set novel physical parameterizations. Turbulent diffusion coefficients computed by SHOC are now used in place of those produced by the boundary layer turbulence and shallow convection parameterizations. Large scale microphysics scheme is no longer used to calculate cloud fraction or the large-scale condensation/deposition. Instead, SHOC provides these quantities. Radiative transfer parameterization uses cloudiness computed by SHOC. An outstanding problem with implementation of SHOC in the NCEP global models is excessively large high level tropical cloudiness. Comparison of the moments of the SGS PDF diagnosed by SHOC to the moments calculated in a GigaLES simulation of tropical deep convection case (GATE), shows that SHOC diagnoses too narrow PDF distributions of total cloud water and MSE in the areas of deep convective detrainment. A subsequent sensitivity study of SHOC's diagnosed cloud fraction (CF) to higher order input moments of the SGS PDF

Reflowing-driven paragraph recognition for electronic books in PDF

Science.gov (United States)

Fang, Jing; Tang, Zhi; Gao, Liangcai

2011-01-01

When reading electronic books on handheld devices, content sometimes should be reflowed and recomposed to adapt for small-screen mobile devices. According to people's reading practice, it is reasonable to reflow the text content based on paragraphs. Hence, this paper addresses the requirement and proposes a set of novel methods on paragraph recognition for electronic books in PDF. The proposed methods consist of three steps, namely, physical structure analysis, paragraph segmentation, and reading order detection. We make use of locally ordered property of PDF documents and layout style of books to improve traditional page recognition results. In addition, we employ the optimal matching of Bipartite Graph technology to detect paragraphs' reading order. Experiments show that our methods achieve high accuracy. It is noteworthy that, the research has been applied in a commercial software package for Chinese E-book production.

e73.pdf.pdf | 92 | OnlineResources | jgenet | www.ias.ac.in | http ...

Indian Academy of Sciences (India)

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A method for measuring the electron drift velocity in working gas using a Frisch-grid ionization chamber

Energy Technology Data Exchange (ETDEWEB)

Bai, Huaiyong; Wang, Zhimin; Zhang, Luyu; Chen, Jinxiang; Zhang, Guohui, E-mail: guohuizhang@pku.edu.cn

2016-12-21

A method for measuring the electron drift velocity in working gas is proposed. Based on the cathode and the anode signal waveforms of the Frisch-grid ionization chamber, the electron drift velocity is extracted. With this method, the electron drift velocities in Ar + 10% CH{sub 4}, Ar + 3.5% CO{sub 2} and Kr + 2.7% CO{sub 2} gases have been measured and the results are compared with the existing measurements and the simulating results. Using this method, the electron drift velocity can be monitored throughout the experiment of charged particle without bothering the measurement of other parameters, such as the energy and orientation.

Fluctuating ideal-gas lattice Boltzmann method with fluctuation dissipation theorem for nonvanishing velocities.

Science.gov (United States)

Kaehler, G; Wagner, A J

2013-06-01

Current implementations of fluctuating ideal-gas descriptions with the lattice Boltzmann methods are based on a fluctuation dissipation theorem, which, while greatly simplifying the implementation, strictly holds only for zero mean velocity and small fluctuations. We show how to derive the fluctuation dissipation theorem for all k, which was done only for k=0 in previous derivations. The consistent derivation requires, in principle, locally velocity-dependent multirelaxation time transforms. Such an implementation is computationally prohibitively expensive but, with a small computational trick, it is feasible to reproduce the correct FDT without overhead in computation time. It is then shown that the previous standard implementations perform poorly for non vanishing mean velocity as indicated by violations of Galilean invariance of measured structure factors. Results obtained with the method introduced here show a significant reduction of the Galilean invariance violations.

Are PDF Documents Accessible?

Directory of Open Access Journals (Sweden)

Mireia Ribera Turró

2008-09-01

Full Text Available Adobe PDF is one of the most widely used formats in scientific communications and in administrative documents. In its latest versions it has incorporated structural tags and improvements that increase its level of accessibility. This article reviews the concept of accessibility in the reading of digital documents and evaluates the accessibility of PDF according to the most widely established standards.

Consideration of some difficulties in migration velocity analysis; Migration velocity analysis no shomondai ni kansuru kento

Energy Technology Data Exchange (ETDEWEB)

Akama, K [Japan National Oil Corp., Tokyo (Japan). Technology Research Center; Matsuoka, T [Japan Petroleum Exploration Corp., Tokyo (Japan)

1997-10-22

Concerning migration velocity analysis in the seismic exploration method, two typical techniques, out of velocity analysis techniques using residual moveout in the CIP gather, are verified. Deregowski`s method uses pre-stacking deep-level migration records for velocity analysis to obtain velocities free of spatial inconsistency and not dependent on the velocity structure. This method is very like the conventional DMO velocity analysis method and is easy to understand intuitively. In this method, however, error is apt to be aggravated in the process of obtaining the depth-sector velocity from the time-RMS velocity. Al-Yahya`s method formulates the moveout residual in the CIP gather. This assumes horizontal stratification and a small residual velocity, however, and fails to guarantee convergence in the case of a steep structure or a grave model error. In the updating of the velocity model, in addition, it has to maintain required accuracy and, at the same time, incorporate smoothing to ensure not to deteriorate high convergence. 2 refs., 5 figs.

The Reliability of Individualized Load-Velocity Profiles.

Science.gov (United States)

Banyard, Harry G; Nosaka, K; Vernon, Alex D; Haff, G Gregory

2017-11-15

This study examined the reliability of peak velocity (PV), mean propulsive velocity (MPV), and mean velocity (MV) in the development of load-velocity profiles (LVP) in the full depth free-weight back squat performed with maximal concentric effort. Eighteen resistance-trained men performed a baseline one-repetition maximum (1RM) back squat trial and three subsequent 1RM trials used for reliability analyses, with 48-hours interval between trials. 1RM trials comprised lifts from six relative loads including 20, 40, 60, 80, 90, and 100% 1RM. Individualized LVPs for PV, MPV, or MV were derived from loads that were highly reliable based on the following criteria: intra-class correlation coefficient (ICC) >0.70, coefficient of variation (CV) ≤10%, and Cohen's d effect size (ES) 0.05) between trials, movement velocities, or between linear regression versus second order polynomial fits. PV 20-100% , MPV 20-90% , and MV 20-90% are reliable and can be utilized to develop LVPs using linear regression. Conceptually, LVPs can be used to monitor changes in movement velocity and employed as a method for adjusting sessional training loads according to daily readiness.

Autoreceptor Control of Peptide/Neurotransmitter Corelease from PDF Neurons Determines Allocation of Circadian Activity in Drosophila

Directory of Open Access Journals (Sweden)

Charles Choi

2012-08-01

Full Text Available Drosophila melanogaster flies concentrate behavioral activity around dawn and dusk. This organization of daily activity is controlled by central circadian clock neurons, including the lateral-ventral pacemaker neurons (LNvs that secrete the neuropeptide PDF (pigment dispersing factor. Previous studies have demonstrated the requirement for PDF signaling to PDF receptor (PDFR-expressing dorsal clock neurons in organizing circadian activity. Although LNvs also express functional PDFR, the role of these autoreceptors has remained enigmatic. Here, we show that (1 PDFR activation in LNvs shifts the balance of circadian activity from evening to morning, similar to behavioral responses to summer-like environmental conditions, and (2 this shift is mediated by stimulation of the Gα,s-cAMP pathway and a consequent change in PDF/neurotransmitter corelease from the LNvs. These results suggest another mechanism for environmental control of the allocation of circadian activity and provide new general insight into the role of neuropeptide autoreceptors in behavioral control circuits.

Relationship between throwing velocity, muscle power, and bar velocity during bench press in elite handball players.

Science.gov (United States)

Marques, Mario C; van den Tilaar, Roland; Vescovi, Jason D; Gonzalez-Badillo, Juan Jose

2007-12-01

The purpose of this study was to examine the relationship between ball-throwing velocity during a 3-step running throw and dynamic strength, power, and bar velocity during a concentric-only bench-press exercise in team-handball players. Fourteen elite senior male team-handball players volunteered to participate. Each volunteer had power and bar velocity measured during a concentric-only bench-press test with 26, 36, and 46 kg, as well as having 1-repetition-maximum (1-RMBP) strength determined. Ball-throwing velocity was evaluated with a standard 3-step running throw using a radar gun. Ball-throwing velocity was related to the absolute load lifted during the 1-RMBP (r = .637, P = .014), peak power using 36 kg (r = .586, P = .028) and 46 kg (r = .582, P = .029), and peak bar velocity using 26 kg (r = .563, P = .036) and 36 kg (r = .625, P = .017). The results indicate that throwing velocity of elite team-handball players is related to maximal dynamic strength, peak power, and peak bar velocity. Thus, a training regimen designed to improve ball-throwing velocity in elite male team-handball players should include exercises that are aimed at increasing both strength and power in the upper body.

Hybrid method for determining the parameters of condenser microphones from measured membrane velocities and numerical calculations

DEFF Research Database (Denmark)

Barrera Figueroa, Salvador; Rasmussen, Knud; Jacobsen, Finn

2009-01-01

to this problem is to measure the velocity distribution of the membrane by means of a non-contact method, such as laser vibrometry. The measured velocity distribution can be used together with a numerical formulation such as the boundary element method for estimating the microphone response and other parameters......, e.g., the acoustic center. In this work, such a hybrid method is presented and examined. The velocity distributions of a number of condenser microphones have been determined using a laser vibrometer, and these measured velocity distributions have been used for estimating microphone responses......Typically, numerical calculations of the pressure, free-field, and random-incidence response of a condenser microphone are carried out on the basis of an assumed displacement distribution of the diaphragm of the microphone; the conventional assumption is that the displacement follows a Bessel...

Evaluation of the effect of implanted depleted uranium on male reproductive success, sperm concentration, and sperm velocity

International Nuclear Information System (INIS)

Arfsten, Darryl P.; Schaeffer, David J.; Johnson, Eric W.; Robert Cunningham, J.; Still, Kenneth R.; Wilfong, Erin R.

2006-01-01

Depleted uranium (DU) projectiles have been used in battle in Iraq and the Balkans and will continue to be a significant armor-penetrating munition for the US military. As demonstrated in the Persian Gulf War, battle injury from DU projectiles and shrapnel is a possibility, and removal of embedded DU fragments from the body is not always practical because of their location in the body or their small size. Previous studies in rodents have demonstrated that implanted DU mobilizes and translocates to the gonads, and natural uranium may be toxic to spermatazoa and the male reproductive tract. In this study, the effects of implanted DU pellets on sperm concentration, motility, and male reproductive success were evaluated in adult (P1) Sprague-Dawley rats implanted with 0, 12, or 20, DU pellets of 1x2 mm or 12 or 20 tantalum (Ta) steel pellets of 1x2 mm. Twenty DU pellets of 1x2 mm (760 mg) implanted in a 500-g rat are equal to approximately 0.2 pound of DU in a 154-lb (70-kg) person. Urinary analysis found that male rats implanted with DU were excreting uranium at postimplantation days 27 and 117 with the amount dependent on dose. No deaths or evidence of toxicity occurred in P1 males over the 150-day postimplantation study period. When assessed at postimplantation day 150, the concentration, motion, and velocity of sperm isolated from DU-implanted animals were not significantly different from those of sham surgery controls. Velocity and motion of sperm isolated from rats treated with the positive control compound α-chlorohydrin were significantly reduced compared with sham surgery controls. There was no evidence of a detrimental effect of DU implantation on mating success at 30-45 days and 120-145 days postimplantation. The results of this study suggest that implantation of up to 20 DU pellets of 1x2 mm in rats for approximately 21% of their adult lifespan does not have an adverse impact on male reproductive success, sperm concentration, or sperm velocity

Layout-aware text extraction from full-text PDF of scientific articles.

Science.gov (United States)

Ramakrishnan, Cartic; Patnia, Abhishek; Hovy, Eduard; Burns, Gully Apc

2012-05-28

The Portable Document Format (PDF) is the most commonly used file format for online scientific publications. The absence of effective means to extract text from these PDF files in a layout-aware manner presents a significant challenge for developers of biomedical text mining or biocuration informatics systems that use published literature as an information source. In this paper we introduce the 'Layout-Aware PDF Text Extraction' (LA-PDFText) system to facilitate accurate extraction of text from PDF files of research articles for use in text mining applications. Our paper describes the construction and performance of an open source system that extracts text blocks from PDF-formatted full-text research articles and classifies them into logical units based on rules that characterize specific sections. The LA-PDFText system focuses only on the textual content of the research articles and is meant as a baseline for further experiments into more advanced extraction methods that handle multi-modal content, such as images and graphs. The system works in a three-stage process: (1) Detecting contiguous text blocks using spatial layout processing to locate and identify blocks of contiguous text, (2) Classifying text blocks into rhetorical categories using a rule-based method and (3) Stitching classified text blocks together in the correct order resulting in the extraction of text from section-wise grouped blocks. We show that our system can identify text blocks and classify them into rhetorical categories with Precision1 = 0.96% Recall = 0.89% and F1 = 0.91%. We also present an evaluation of the accuracy of the block detection algorithm used in step 2. Additionally, we have compared the accuracy of the text extracted by LA-PDFText to the text from the Open Access subset of PubMed Central. We then compared this accuracy with that of the text extracted by the PDF2Text system, 2commonly used to extract text from PDF. Finally, we discuss preliminary error analysis for

Layout-aware text extraction from full-text PDF of scientific articles

Directory of Open Access Journals (Sweden)

Ramakrishnan Cartic

2012-05-01

Full Text Available Abstract Background The Portable Document Format (PDF is the most commonly used file format for online scientific publications. The absence of effective means to extract text from these PDF files in a layout-aware manner presents a significant challenge for developers of biomedical text mining or biocuration informatics systems that use published literature as an information source. In this paper we introduce the ‘Layout-Aware PDF Text Extraction’ (LA-PDFText system to facilitate accurate extraction of text from PDF files of research articles for use in text mining applications. Results Our paper describes the construction and performance of an open source system that extracts text blocks from PDF-formatted full-text research articles and classifies them into logical units based on rules that characterize specific sections. The LA-PDFText system focuses only on the textual content of the research articles and is meant as a baseline for further experiments into more advanced extraction methods that handle multi-modal content, such as images and graphs. The system works in a three-stage process: (1 Detecting contiguous text blocks using spatial layout processing to locate and identify blocks of contiguous text, (2 Classifying text blocks into rhetorical categories using a rule-based method and (3 Stitching classified text blocks together in the correct order resulting in the extraction of text from section-wise grouped blocks. We show that our system can identify text blocks and classify them into rhetorical categories with Precision1 = 0.96% Recall = 0.89% and F1 = 0.91%. We also present an evaluation of the accuracy of the block detection algorithm used in step 2. Additionally, we have compared the accuracy of the text extracted by LA-PDFText to the text from the Open Access subset of PubMed Central. We then compared this accuracy with that of the text extracted by the PDF2Text system, 2commonly used to extract text from PDF

Qualitative XRD - use of the PDF for beginners and the evolution of the ICDD

International Nuclear Information System (INIS)

Hubbard, C.R.

2002-01-01

Full text: The Powder Diffraction File (PDF), published by the International Centre for Diffraction Data (ICDD), has traditionally been used for phase identification by x-ray diffraction methods and is widely used in establishing the phases present in reaction, corrosion and decomposition products in fields including mineralogy, materials science, manufacturing and pharmaceuticals. The X-ray diffraction reference patterns of the PDF have been collected and edited by the non profit organization known today as the International Centre for Diffraction Data (ICDD). Recent activities by the ICDD have greatly enhanced the PDF based on collaboration with structural data centers, expanding the pattern producing Grants-in-Aid program, and focussing efforts of task groups of the ICDD Technical Committee. The currently evolving needs of combinatorial scientists, pharmaceutical laboratories, and computational materials science will impact the PDF in coming years. One opportunity is for greater cross-linking of characterization and property databases and the efforts to explore this future will be discussed. This presentation will survey the evolution of the organization and the PDF emphasizing the more recent changes, summarize the contents of the PDF, present highlights of how to use the powder diffraction file for phase identification, and highlight advantages of the forthcoming relational database format for the PDF. Copyright (2002) Australian X-ray Analytical Association Inc

Theoretical analysis of stack gas emission velocity measurement by optical scintillation

International Nuclear Information System (INIS)

Yang Yang; Dong Feng-Zhong; Ni Zhi-Bo; Pang Tao; Zeng Zong-Yong; Wu Bian; Zhang Zhi-Rong

2014-01-01

Theoretical analysis for an online measurement of the stack gas flow velocity based on the optical scintillation method with a structure of two parallel optical paths is performed. The causes of optical scintillation in a stack are first introduced. Then, the principle of flow velocity measurement and its mathematical expression based on cross correlation of the optical scintillation are presented. The field test results show that the flow velocity measured by the proposed technique in this article is consistent with the value tested by the Pitot tube. It verifies the effectiveness of this method. Finally, by use of the structure function of logarithmic light intensity fluctuations, the theoretical explanation of optical scintillation spectral characteristic in low frequency is given. The analysis of the optical scintillation spectrum provides the basis for the measurement of the stack gas flow velocity and particle concentration simultaneously. (general)

A low noise discrete velocity method for the Boltzmann equation with quantized rotational and vibrational energy

Science.gov (United States)

Clarke, Peter; Varghese, Philip; Goldstein, David

2018-01-01

A discrete velocity method is developed for gas mixtures of diatomic molecules with both rotational and vibrational energy states. A full quantized model is described, and rotation-translation and vibration-translation energy exchanges are simulated using a Larsen-Borgnakke exchange model. Elastic and inelastic molecular interactions are modeled during every simulated collision to help produce smooth internal energy distributions. The method is verified by comparing simulations of homogeneous relaxation by our discrete velocity method to numerical solutions of the Jeans and Landau-Teller equations, and to direct simulation Monte Carlo. We compute the structure of a 1D shock using this method, and determine how the rotational energy distribution varies with spatial location in the shock and with position in velocity space.

Trajectory Generation Method with Convolution Operation on Velocity Profile

Energy Technology Data Exchange (ETDEWEB)

Lee, Geon [Hanyang Univ., Seoul (Korea, Republic of); Kim, Doik [Korea Institute of Science and Technology, Daejeon (Korea, Republic of)

2014-03-15

The use of robots is no longer limited to the field of industrial robots and is now expanding into the fields of service and medical robots. In this light, a trajectory generation method that can respond instantaneously to the external environment is strongly required. Toward this end, this study proposes a method that enables a robot to change its trajectory in real-time using a convolution operation. The proposed method generates a trajectory in real time and satisfies the physical limits of the robot system such as acceleration and velocity limit. Moreover, a new way to improve the previous method, which generates inefficient trajectories in some cases owing to the characteristics of the trapezoidal shape of trajectories, is proposed by introducing a triangle shape. The validity and effectiveness of the proposed method is shown through a numerical simulation and a comparison with the previous convolution method.

Point Measurements of Fermi Velocities by a Time-of-Flight Method

DEFF Research Database (Denmark)

Falk, David S.; Henningsen, J. O.; Skriver, Hans Lomholt

1972-01-01

The present paper describes in detail a new method of obtaining information about the Fermi velocity of electrons in metals, point by point, along certain contours on the Fermi surface. It is based on transmission of microwaves through thin metal slabs in the presence of a static magnetic field...... applied parallel to the surface. The electrons carry the signal across the slab and arrive at the second surface with a phase delay which is measured relative to a reference signal; the velocities are derived by analyzing the magnetic field dependence of the phase delay. For silver we have in this way...... obtained one component of the velocity along half the circumference of the centrally symmetric orbit for B→∥[100]. The results are in agreement with current models for the Fermi surface. For B→∥[011], the electrons involved are not moving in a symmetry plane of the Fermi surface. In such cases one cannot...

Autoreceptor Modulation of Peptide/Neurotransmitter Co-release from PDF Neurons Determines Allocation of Circadian Activity in Drosophila

Science.gov (United States)

Choi, Charles; Cao, Guan; Tanenhaus, Anne K.; McCarthy, Ellena v.; Jung, Misun; Schleyer, William; Shang, Yuhua; Rosbash, Michael; Yin, Jerry C.P.; Nitabach, Michael N.

2012-01-01

Drosophila melanogaster flies concentrate behavioral activity around dawn and dusk. This organization of daily activity is controlled by central circadian clock neurons, including the lateral ventral pacemaker neurons (LNvs) that secrete the neuropeptide PDF (Pigment Dispersing Factor). Previous studies have demonstrated the requirement for PDF signaling to PDF receptor (PDFR)-expressing dorsal clock neurons in organizing circadian activity. While LNvs also express functional PDFR, the role of these autoreceptors has remained enigmatic. Here we show that (1) PDFR activation in LNvs shifts the balance of circadian activity from evening to morning, similar to behavioral responses to summer-like environmental conditions and (2) this shift is mediated by stimulation of the Ga,s-cAMP pathway and a consequent change in PDF/neurotransmitter co-release from the LNvs. These results suggest a novel mechanism for environmental control of the allocation of circadian activity and provide new general insight into the role of neuropeptide autoreceptors in behavioral control circuits. PMID:22938867

Applicability of Stokes method for measuring viscosity of mixtures with concentration gradient

Directory of Open Access Journals (Sweden)

César Medina

2017-12-01

Full Text Available After measuring density and viscosity of a mixture of glycerin and water contained in a vertical pipe, a variation of these properties according to depth is observed. These gradients are typical of non-equilibrium states related to the lower density of water and the fact that relatively long times are necessary to achieve homogeneity. In the same pipe, the falling velocity of five little spheres is measured as a function of depth, and then a numerical fit is performed which agrees very well with experimental data. Based on the generalization of these results, the applicability of Stokes method is discussed for measuring viscosity of mixtures with a concentration gradient.

PDF4LHC recommendations for LHC Run II

NARCIS (Netherlands)

Butterworth, Jon; Carrazza, Stefano; Cooper-Sarkar, Amanda; Roeck, Albert de; Feltesse, Joel; Forte, Stefano; Gao, Jun; Glazov, Sasha; Huston, Joey; Kassabov, Zahari; McNulty, Ronan; Morsch, Andreas; Nadolsky, Pavel; Radescu, Voica; Rojo, Juan; Thorne, Robert S.

2015-01-01

We provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\\alpha_s$ uncertainties suitable for applications at the LHC Run II. We review developments since the previous PDF4LHC recommendation, and discuss and compare the new

System and method for investigating sub-surface features and 3D imaging of non-linear property, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation

Science.gov (United States)

Vu, Cung Khac; Skelt, Christopher; Nihei, Kurt; Johnson, Paul A.; Guyer, Robert; Ten Cate, James A.; Le Bas, Pierre-Yves; Larmat, Carene S.

2015-06-02

A system and a method for generating a three-dimensional image of a rock formation, compressional velocity VP, shear velocity VS and velocity ratio VP/VS of a rock formation are provided. A first acoustic signal includes a first plurality of pulses. A second acoustic signal from a second source includes a second plurality of pulses. A detected signal returning to the borehole includes a signal generated by a non-linear mixing process from the first and second acoustic signals in a non-linear mixing zone within an intersection volume. The received signal is processed to extract the signal over noise and/or signals resulting from linear interaction and the three dimensional image of is generated.

Determination of the filtration velocities and mean velocity in ground waters using radiotracers

International Nuclear Information System (INIS)

Duran P, Oscar; Diaz V, Francisco; Heresi M, Nelida

1994-01-01

An experimental method to determine filtration, or, Darcy velocity and mean velocity in underground waters using radiotracers, is described. After selecting the most appropriate tracers, from 6 chemical compounds, to measure water velocity, a method to measure filtration velocity was developed. By fully labelling the water column with 2 radioisotopes, Br and tritium, almost identical values were obtained for the aquifer filtration velocity in the sounding S1. This value was 0.04 m/d. Field porosity was calculated at 11% and mean velocity at 0.37 m.d. With the filtration velocity value and knowing the hydraulic variation between the soundings S1 and S2 placed at 10 meters, field permeability was estimated at 2.4 x 10 m/s. (author)

Maximum entropy PDF projection: A review

Science.gov (United States)

Baggenstoss, Paul M.

2017-06-01

We review maximum entropy (MaxEnt) PDF projection, a method with wide potential applications in statistical inference. The method constructs a sampling distribution for a high-dimensional vector x based on knowing the sampling distribution p(z) of a lower-dimensional feature z = T (x). Under mild conditions, the distribution p(x) having highest possible entropy among all distributions consistent with p(z) may be readily found. Furthermore, the MaxEnt p(x) may be sampled, making the approach useful in Monte Carlo methods. We review the theorem and present a case study in model order selection and classification for handwritten character recognition.

New Tools to Convert PDF Math Contents into Accessible e-Books Efficiently.

Science.gov (United States)

Suzuki, Masakazu; Terada, Yugo; Kanahori, Toshihiro; Yamaguchi, Katsuhito

2015-01-01

New features in our math-OCR software to convert PDF math contents into accessible e-books are shown. A method for recognizing PDF is thoroughly improved. In addition, contents in any selected area including math formulas in a PDF file can be cut and pasted into a document in various accessible formats, which is automatically recognized and converted into texts and accessible math formulas through this process. Combining it with our authoring tool for a technical document, one can easily produce accessible e-books in various formats such as DAISY, accessible EPUB3, DAISY-like HTML5, Microsoft Word with math objects and so on. Those contents are useful for various print-disabled students ranging from the blind to the dyslexic.

Autoreceptor control of peptide/neurotransmitter corelease from PDF neurons determines allocation of circadian activity in drosophila.

Science.gov (United States)

Choi, Charles; Cao, Guan; Tanenhaus, Anne K; McCarthy, Ellena V; Jung, Misun; Schleyer, William; Shang, Yuhua; Rosbash, Michael; Yin, Jerry C P; Nitabach, Michael N

2012-08-30

Drosophila melanogaster flies concentrate behavioral activity around dawn and dusk. This organization of daily activity is controlled by central circadian clock neurons, including the lateral-ventral pacemaker neurons (LN(v)s) that secrete the neuropeptide PDF (pigment dispersing factor). Previous studies have demonstrated the requirement for PDF signaling to PDF receptor (PDFR)-expressing dorsal clock neurons in organizing circadian activity. Although LN(v)s also express functional PDFR, the role of these autoreceptors has remained enigmatic. Here, we show that (1) PDFR activation in LN(v)s shifts the balance of circadian activity from evening to morning, similar to behavioral responses to summer-like environmental conditions, and (2) this shift is mediated by stimulation of the Gα,s-cAMP pathway and a consequent change in PDF/neurotransmitter corelease from the LN(v)s. These results suggest another mechanism for environmental control of the allocation of circadian activity and provide new general insight into the role of neuropeptide autoreceptors in behavioral control circuits. Copyright © 2012 The Authors. Published by Elsevier Inc. All rights reserved.

A PRACTICAL APPROACH TO THE GROUND OSCILLATION VELOCITY MEASUREMENT METHOD

Directory of Open Access Journals (Sweden)

Siniša Stanković

2017-01-01

Full Text Available The use of an explosive’s energy during blasting includes undesired effects on the environment. The seismic influence of a blast, as a major undesired effect, is determined by many national standards, recommendations and calculations where the main parameter is ground oscillation velocity at the field measurement location. There are a few approaches and methods for calculation of expected ground oscillation velocities according to charge weight per delay and the distance from the blast to the point of interest. Utilizations of these methods and formulas do not provide satisfactory results, thus the measured values on diverse distance from the blast field more or less differ from values given by previous calculations. Since blasting works are executed in diverse geological conditions, the aim of this research is the development of a practical and reliable approach which will give a different model for each construction site where blasting works have been or will be executed. The approach is based on a greater number of measuring points in line from the blast field at predetermined distances. This new approach has been compared with other generally used methods and formulas through the use of measurements taken during research along with measurements from several previously executed projects. The results confirmed that the suggested model gives more accurate values.

PDF4LHC recommendations for LHC Run II

CERN Document Server

Butterworth, Jon; Cooper-Sarkar, Amanda; De Roeck, Albert; Feltesse, Joel; Forte, Stefano; Gao, Jun; Glazov, Sasha; Huston, Joey; Kassabov, Zahari; McNulty, Ronan; Morsch, Andreas; Nadolsky, Pavel; Radescu, Voica; Rojo, Juan; Thorne, Robert

2016-01-01

We provide an updated recommendation for the usage of sets of parton distribution functions (PDFs) and the assessment of PDF and PDF+$\\alpha_s$ uncertainties suitable for applications at the LHC Run II. We review developments since the previous PDF4LHC recommendation, and discuss and compare the new generation of PDFs, which include substantial information from experimental data from the Run I of the LHC. We then propose a new prescription for the combination of a suitable subset of the available PDF sets, which is presented in terms of a single combined PDF set. We finally discuss tools which allow for the delivery of this combined set in terms of optimized sets of Hessian eigenvectors or Monte Carlo replicas, and their usage, and provide some examples of their application to LHC phenomenology.

Comparative study of the discrete velocity and lattice Boltzmann methods for rarefied gas flows through irregular channels.

Science.gov (United States)

Su, Wei; Lindsay, Scott; Liu, Haihu; Wu, Lei

2017-08-01

Rooted from the gas kinetics, the lattice Boltzmann method (LBM) is a powerful tool in modeling hydrodynamics. In the past decade, it has been extended to simulate rarefied gas flows beyond the Navier-Stokes level, either by using the high-order Gauss-Hermite quadrature, or by introducing the relaxation time that is a function of the gas-wall distance. While the former method, with a limited number of discrete velocities (e.g., D2Q36), is accurate up to the early transition flow regime, the latter method (especially the multiple relaxation time (MRT) LBM), with the same discrete velocities as those used in simulating hydrodynamics (i.e., D2Q9), is accurate up to the free-molecular flow regime in the planar Poiseuille flow. This is quite astonishing in the sense that less discrete velocities are more accurate. In this paper, by solving the Bhatnagar-Gross-Krook kinetic equation accurately via the discrete velocity method, we find that the high-order Gauss-Hermite quadrature cannot describe the large variation in the velocity distribution function when the rarefaction effect is strong, but the MRT-LBM can capture the flow velocity well because it is equivalent to solving the Navier-Stokes equations with an effective shear viscosity. Since the MRT-LBM has only been validated in simple channel flows, and for complex geometries it is difficult to find the effective viscosity, it is necessary to assess its performance for the simulation of rarefied gas flows. Our numerical simulations based on the accurate discrete velocity method suggest that the accuracy of the MRT-LBM is reduced significantly in the simulation of rarefied gas flows through the rough surface and porous media. Our simulation results could serve as benchmarking cases for future development of the LBM for modeling and simulation of rarefied gas flows in complex geometries.

Comparative study of the discrete velocity and lattice Boltzmann methods for rarefied gas flows through irregular channels

Science.gov (United States)

Su, Wei; Lindsay, Scott; Liu, Haihu; Wu, Lei

2017-08-01

Rooted from the gas kinetics, the lattice Boltzmann method (LBM) is a powerful tool in modeling hydrodynamics. In the past decade, it has been extended to simulate rarefied gas flows beyond the Navier-Stokes level, either by using the high-order Gauss-Hermite quadrature, or by introducing the relaxation time that is a function of the gas-wall distance. While the former method, with a limited number of discrete velocities (e.g., D2Q36), is accurate up to the early transition flow regime, the latter method (especially the multiple relaxation time (MRT) LBM), with the same discrete velocities as those used in simulating hydrodynamics (i.e., D2Q9), is accurate up to the free-molecular flow regime in the planar Poiseuille flow. This is quite astonishing in the sense that less discrete velocities are more accurate. In this paper, by solving the Bhatnagar-Gross-Krook kinetic equation accurately via the discrete velocity method, we find that the high-order Gauss-Hermite quadrature cannot describe the large variation in the velocity distribution function when the rarefaction effect is strong, but the MRT-LBM can capture the flow velocity well because it is equivalent to solving the Navier-Stokes equations with an effective shear viscosity. Since the MRT-LBM has only been validated in simple channel flows, and for complex geometries it is difficult to find the effective viscosity, it is necessary to assess its performance for the simulation of rarefied gas flows. Our numerical simulations based on the accurate discrete velocity method suggest that the accuracy of the MRT-LBM is reduced significantly in the simulation of rarefied gas flows through the rough surface and porous media. Our simulation results could serve as benchmarking cases for future development of the LBM for modeling and simulation of rarefied gas flows in complex geometries.

A Simple Method for Assessing Upper-Limb Force-Velocity Profile in Bench Press.

Science.gov (United States)

Rahmani, Abderrahmane; Samozino, Pierre; Morin, Jean-Benoit; Morel, Baptiste

2018-02-01

To analyze the reliability and validity of a field computation method based on easy-to-measure data to assess the mean force ([Formula: see text]) and velocity ([Formula: see text]) produced during a ballistic bench-press movement and to verify that the force-velocity profile (F-v) obtained with multiple loaded trials is accurately described. Twelve participants performed ballistic bench presses against various lifted mass from 30% to 70% of their body mass. For each trial, [Formula: see text] and [Formula: see text] were determined from an accelerometer (sampling rate 500 Hz; reference method) and a simple computation method based on upper-limb mass, barbell flight height, and push-off distance. These [Formula: see text] and [Formula: see text] data were used to establish the F-v relationship for each individual and method. A strong to almost perfect reliability was observed between the 2 trials (ICC > .90 for [Formula: see text] and .80 for [Formula: see text], CV%  .80, P push-off distance).

The PDF4LHC Working Group Interim Report

CERN Document Server

Alekhin, Sergey; Ball, Richard D.; Bertone, Valerio; Blumlein, Johannes; Botje, Michiel; Butterworth, Jon; Cerutti, Francesco; Cooper-Sarkar, Amanda; de Roeck, Albert; Del Debbio, Luigi; Feltesse, Joel; Forte, Stefano; Glazov, Alexander; Guffanti, Alberto; Gwenlan, Claire; Huston, Joey; Jimenez-Delgado, Pedro; Lai, Hung-Liang; Latorre, Jose I.; McNulty, Ronan; Nadolsky, Pavel; Olaf Moch, Sven; Pumplin, Jon; Radescu, Voica; Rojo, Juan; Sjostrand, Torbjorn; Stirling, W.J.; Stump, Daniel; Thorne, Robert S.; Ubiali, Maria; Vicini, Alessandro; Watt, Graeme; Yuan, C.-P.

2011-01-01

This document is intended as a study of benchmark cross sections at the LHC (at 7 TeV) at NLO using modern parton distribution functions currently available from the 6 PDF fitting groups that have participated in this exercise. It also contains a succinct user guide to the computation of PDFs, uncertainties and correlations using available PDF sets. A companion note, also submitted to the archive, provides an interim summary of the current recommendations of the PDF4LHC working group for the use of parton distribution functions and of PDF uncertainties at the LHC, for cross section and cross section uncertainty calculations.

A Comprehensive Study of Gridding Methods for GPS Horizontal Velocity Fields

Science.gov (United States)

Wu, Yanqiang; Jiang, Zaisen; Liu, Xiaoxia; Wei, Wenxin; Zhu, Shuang; Zhang, Long; Zou, Zhenyu; Xiong, Xiaohui; Wang, Qixin; Du, Jiliang

2017-03-01

Four gridding methods for GPS velocities are compared in terms of their precision, applicability and robustness by analyzing simulated data with uncertainties from 0.0 to ±3.0 mm/a. When the input data are 1° × 1° grid sampled and the uncertainty of the additional error is greater than ±1.0 mm/a, the gridding results show that the least-squares collocation method is highly robust while the robustness of the Kriging method is low. In contrast, the spherical harmonics and the multi-surface function are moderately robust, and the regional singular values for the multi-surface function method and the edge effects for the spherical harmonics method become more significant with increasing uncertainty of the input data. When the input data (with additional errors of ±2.0 mm/a) are decimated by 50% from the 1° × 1° grid data and then erased in three 6° × 12° regions, the gridding results in these three regions indicate that the least-squares collocation and the spherical harmonics methods have good performances, while the multi-surface function and the Kriging methods may lead to singular values. The gridding techniques are also applied to GPS horizontal velocities with an average error of ±0.8 mm/a over the Chinese mainland and the surrounding areas, and the results show that the least-squares collocation method has the best performance, followed by the Kriging and multi-surface function methods. Furthermore, the edge effects of the spherical harmonics method are significantly affected by the sparseness and geometric distribution of the input data. In general, the least-squares collocation method is superior in terms of its robustness, edge effect, error distribution and stability, while the other methods have several positive features.

Fulltext PDF

Indian Academy of Sciences (India)

the list of essential medicines of the World Health Organization1. Thiamine ... he was just 27!), he published a full paper in the Journal of the American Chemical Society, which for the first time elaborated how ... EML2015_8-May-15.pdf.

Remote determination of the velocity index and mean streamwise velocity profiles

Science.gov (United States)

Johnson, E. D.; Cowen, E. A.

2017-09-01

When determining volumetric discharge from surface measurements of currents in a river or open channel, the velocity index is typically used to convert surface velocities to depth-averaged velocities. The velocity index is given by, k=Ub/Usurf, where Ub is the depth-averaged velocity and Usurf is the local surface velocity. The USGS (United States Geological Survey) standard value for this coefficient, k = 0.85, was determined from a series of laboratory experiments and has been widely used in the field and in laboratory measurements of volumetric discharge despite evidence that the velocity index is site-specific. Numerous studies have documented that the velocity index varies with Reynolds number, flow depth, and relative bed roughness and with the presence of secondary flows. A remote method of determining depth-averaged velocity and hence the velocity index is developed here. The technique leverages the findings of Johnson and Cowen (2017) and permits remote determination of the velocity power-law exponent thereby, enabling remote prediction of the vertical structure of the mean streamwise velocity, the depth-averaged velocity, and the velocity index.

Local measurement of interfacial area, interfacial velocity and liquid turbulence in two-phase flow

International Nuclear Information System (INIS)

Hibiki, T.; Hogsett, S.; Ishii, M.

1998-01-01

Double sensor probe and hotfilm anemometry methods were developed for measuring local flow characteristics in bubbly flow. The formulation for the interfacial area concentration measurement was obtained by improving the formulation derived by Kataoka and Ishii. The assumptions used in the derivation of the equation were verified experimentally. The interfacial area concentration measured by the double sensor probe agreed well with one by the photographic method. The filter to validate the hotfilm anemometry for measuring the liquid velocity and turbulent intensity in bubbly flow was developed based on removing the signal due to the passing bubbles. The local void fraction, interfacial area concentration, interfacial velocity, Sauter mean diameter, liquid velocity, and turbulent intensity of vertical upward air-water flow in a round tube with inner diameter of 50.8 mm were measured by using these methods. A total of 54 data sets were acquired consisting of three superficial gas flow rates, 0.039, 0.067, and 0.147 m/s, and three superficial liquid flow rates, 0.60, 1.00, and 1.30 m/s. The measurements were performed at the three locations: L/D=2, 32, and 62. This data is expected to be used for the development of reliable constitutive relations which reflect the true transfer mechanisms in two-phase flow. (author)

Crystal growth velocity in deeply undercooled Ni-Si alloys

Science.gov (United States)

Lü, Y. J.

2012-02-01

The crystal growth velocity of Ni95Si5 and Ni90Si10 alloys as a function of undercooling is investigated using molecular dynamics simulations. The modified imbedded atom method potential yields the equilibrium liquidus temperatures T L ≈ 1505 and 1387 K for Ni95Si5 and Ni90Si10 alloys, respectively. From the liquidus temperatures down to the deeply undercooled region, the crystal growth velocities of both the alloys rise to the maximum with increasing undercooling and then drop slowly, whereas the athermal growth process presented in elemental Ni is not observed in Ni-Si alloys. Instead, the undercooling dependence of the growth velocity can be well-described by the diffusion-limited model, furthermore, the activation energy associated with the diffusion from melt to interface increases as the concentration increases from 5 to 10 at.% Si, resulting in the remarkable decrease of growth velocity.

Evaluation of an ion adsorption method to estimate intragravel flow velocity in salmonid spawning gravels

Science.gov (United States)

James L. Clayton; John G. King; Russell F. Thurow

1996-01-01

Intragravel water exchange provides oxygenated water, removes metabolic waste, and is an essential factor in salmonid embryo survival. Measurements of intragravel flow velocity have been suggested as an index of gravel quality and also as a useful predictor of fry emergence; however, proposed methods for measuring velocity in gravel are problematic. We evaluate an ion...

Method of enriching oil shale concentrate

Energy Technology Data Exchange (ETDEWEB)

Larsson, M

1942-02-14

The method is characterized by producing one concentrate first and then this concentrate, in water solution using suitable apparatus, is separated by settling into one heavier bottom portion, rich in mineral matter, and into a lighter slime containing concentrated organic substance.

Deep PDF parsing to extract features for detecting embedded malware.

Energy Technology Data Exchange (ETDEWEB)

Munson, Miles Arthur; Cross, Jesse S. (Missouri University of Science and Technology, Rolla, MO)

2011-09-01

The number of PDF files with embedded malicious code has risen significantly in the past few years. This is due to the portability of the file format, the ways Adobe Reader recovers from corrupt PDF files, the addition of many multimedia and scripting extensions to the file format, and many format properties the malware author may use to disguise the presence of malware. Current research focuses on executable, MS Office, and HTML formats. In this paper, several features and properties of PDF Files are identified. Features are extracted using an instrumented open source PDF viewer. The feature descriptions of benign and malicious PDFs can be used to construct a machine learning model for detecting possible malware in future PDF files. The detection rate of PDF malware by current antivirus software is very low. A PDF file is easy to edit and manipulate because it is a text format, providing a low barrier to malware authors. Analyzing PDF files for malware is nonetheless difficult because of (a) the complexity of the formatting language, (b) the parsing idiosyncrasies in Adobe Reader, and (c) undocumented correction techniques employed in Adobe Reader. In May 2011, Esparza demonstrated that PDF malware could be hidden from 42 of 43 antivirus packages by combining multiple obfuscation techniques [4]. One reason current antivirus software fails is the ease of varying byte sequences in PDF malware, thereby rendering conventional signature-based virus detection useless. The compression and encryption functions produce sequences of bytes that are each functions of multiple input bytes. As a result, padding the malware payload with some whitespace before compression/encryption can change many of the bytes in the final payload. In this study we analyzed a corpus of 2591 benign and 87 malicious PDF files. While this corpus is admittedly small, it allowed us to test a system for collecting indicators of embedded PDF malware. We will call these indicators features throughout

Shock loading predictions from application of indicial theory to shock-turbulence interactions

Science.gov (United States)

Keefe, Laurence R.; Nixon, David

1991-01-01

A sequence of steps that permits prediction of some of the characteristics of the pressure field beneath a fluctuating shock wave from knowledge of the oncoming turbulent boundary layer is presented. The theory first predicts the power spectrum and pdf of the position and velocity of the shock wave, which are then used to obtain the shock frequency distribution, and the pdf of the pressure field, as a function of position within the interaction region. To test the validity of the crucial assumption of linearity, the indicial response of a normal shock is calculated from numerical simulation. This indicial response, after being fit by a simple relaxation model, is used to predict the shock position and velocity spectra, along with the shock passage frequency distribution. The low frequency portion of the shock spectra, where most of the energy is concentrated, is satisfactorily predicted by this method.

Assessment of the influence factors on nasal spray droplet velocity using phase-Doppler anemometry (PDA).

Science.gov (United States)

Liu, Xiaofei; Doub, William H; Guo, Changning

2011-03-01

Droplet velocity is an important parameter that can be used to characterize nasal spray products. In this study, a phase-Doppler anemometry (PDA) system was used to measure the droplet velocities of nasal sprays. A survey of seven commercial nasal spray products showed a range of droplet velocities from 6.7 to 19.2 m/s, all significantly different from each other. A three-level, four-factor Box-Behnken design of experiments (DOE) methodology were applied to investigate the influences of actuation parameters and formulation properties on nasal spray droplet velocity using a set of placebo formulations. The DOE study shows that all four input factors (stroke length, actuation velocity, concentration of the gelling agent, and concentration of the surfactant) have significant influence on droplet velocity. An optimized quadratic model generated from the DOE results describes the inherent relationships between the input factors and droplet velocity thus providing a better understanding of the input factor influences. Overall, PDA provides a new in vitro characterization method for the evaluation of inhalation drugs through assessment of spray velocity and may assist in product development to meet drug delivery equivalency requirements. © 2011 American Association of Pharmaceutical Scientists

Study of the dissolution velocity of dispersed solid particles. Development of a calculation method for analyzing the kinetic curves. Extension to the study of composed kinetics

International Nuclear Information System (INIS)

Jorda, Michel.

1976-01-01

The dissolution of a solid in an aqueous phase is studied, the solid consisting of dispersed particles. A continuous colorimetric analysis method is developed to study the dissolution process and a two-parameter optimization method is established to investigate the kinetic curves obtained. This method is based on the differential equation dx/dt=K(1-x)sup(n). (n being the decrease in the dissolution velocity when the dissolved part increases and K a velocity parameter). The dissolution of SO 4 Cu and MnO 4 K in water and UO 3 in SO 4 H 2 is discussed. It is shown that the dissolution velocity of UO 3 is proportional to the concentration of the H + ions in the solution as far as this one is not higher than 0.25N. The study of the temperature dependence of the UO 3 dissolution reaction shows that a transition phase takes place from 25 to 65 0 C between a phase in which the dissolution is controlled by the diffusion of the H + ions and the chemical reaction at the interface and a phase in which the kinetics is only controlled by the diffusion [fr

Alignment method for parabolic trough solar concentrators

Science.gov (United States)

Diver, Richard B [Albuquerque, NM

2010-02-23

A Theoretical Overlay Photographic (TOP) alignment method uses the overlay of a theoretical projected image of a perfectly aligned concentrator on a photographic image of the concentrator to align the mirror facets of a parabolic trough solar concentrator. The alignment method is practical and straightforward, and inherently aligns the mirror facets to the receiver. When integrated with clinometer measurements for which gravity and mechanical drag effects have been accounted for and which are made in a manner and location consistent with the alignment method, all of the mirrors on a common drive can be aligned and optimized for any concentrator orientation.

Measurements of P- and S wave velocities in a rock massif and its use in estimating elastic moduli

Czech Academy of Sciences Publication Activity Database

Živor, Roman; Vilhelm, J.; Rudajev, Vladimír; Lokajíček, Tomáš

2011-01-01

Roč. 8, č. 2 (2011), s. 157-167 ISSN 1214-9705 R&D Projects: GA AV ČR IAA300130906 Institutional research plan: CEZ:AV0Z30130516 Keywords : seismic source * seismic waves velocity * elastic constants * geophone * piezo -electric transducer Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/abstracts/AGG/02_11/6_Zivor.pdf

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Indian Academy of Sciences (India)

PRAKASH

11% due to surface water velocity (SWV) in the river Cauvery and 11% due to temperature in the river Kapila. ...... 2000) and in sediments of Botany Bay in Sydney, Australia, ... APHA 1992 Standard methods for examination of water and waste.

Analysis shear wave velocity structure obtained from surface wave methods in Bornova, Izmir

Energy Technology Data Exchange (ETDEWEB)

Pamuk, Eren, E-mail: eren.pamuk@deu.edu.tr; Akgün, Mustafa, E-mail: mustafa.akgun@deu.edu.tr [Department of Geophysical Engineering, Dokuz Eylul University, Izmir (Turkey); Özdağ, Özkan Cevdet, E-mail: cevdet.ozdag@deu.edu.tr [Dokuz Eylul University Rectorate, Izmir (Turkey)

2016-04-18

Properties of the soil from the bedrock is necessary to describe accurately and reliably for the reduction of earthquake damage. Because seismic waves change their amplitude and frequency content owing to acoustic impedance difference between soil and bedrock. Firstly, shear wave velocity and depth information of layers on bedrock is needed to detect this changing. Shear wave velocity can be obtained using inversion of Rayleigh wave dispersion curves obtained from surface wave methods (MASW- the Multichannel Analysis of Surface Waves, ReMi-Refraction Microtremor, SPAC-Spatial Autocorrelation). While research depth is limeted in active source study, a passive source methods are utilized for deep depth which is not reached using active source methods. ReMi method is used to determine layer thickness and velocity up to 100 m using seismic refraction measurement systems.The research carried out up to desired depth depending on radius using SPAC which is utilized easily in conditions that district using of seismic studies in the city. Vs profiles which are required to calculate deformations in under static and dynamic loads can be obtained with high resolution using combining rayleigh wave dispersion curve obtained from active and passive source methods. In the this study, Surface waves data were collected using the measurements of MASW, ReMi and SPAC at the İzmir Bornova region. Dispersion curves obtained from surface wave methods were combined in wide frequency band and Vs-depth profiles were obtained using inversion. Reliability of the resulting soil profiles were provided by comparison with theoretical transfer function obtained from soil paremeters and observed soil transfer function from Nakamura technique and by examination of fitting between these functions. Vs values are changed between 200-830 m/s and engineering bedrock (Vs>760 m/s) depth is approximately 150 m.

A metronome for controlling the mean velocity during the bench press exercise.

Science.gov (United States)

Moras, Gerard; Rodríguez-Jiménez, Sergio; Busquets, Albert; Tous-Fajardo, Julio; Pozzo, Marco; Mujika, Iñigo

2009-05-01

Lifting velocity may have a great impact on strength training-induced adaptations. The purpose of this study was to validate a method including a metronome and a measurement tape as inexpensive tools for the estimation of mean lifting velocity during the bench press exercise. Fifteen subjects participated in this study. After determining their one repetition maximum (1RM) load, we estimated the maximum metronome rhythm (R) that each subject could maintain in the concentric phase for loads of 40 and 60% of 1RM. To estimate R, the 3 repetitions with highest concentric power, as measured by means of a linear encoder, were selected, and their average duration was calculated and converted to lifting rhythm in beats per minute (bpm) for each subject. The range of motion was measured using a regular tape and kept constant during all exercises. Subjects were instructed to begin with the barbell at arm lengths and lower it in correspondence with the metronome beep. They subsequently performed 5 repetitions at 3 different rhythms relative to R (50, 70, and 90% R) for each training load (40 and 60% of 1RM). A linear encoder was attached to the bar and used as a criterion to measure the vertical displacement over time. For each rhythm, the mean velocity was calculated with the metronome (time) and the reference distance and compared with that recorded by the linear encoder. The SEM for velocity between both testing methods ranged from 0.02 to 0.05 m.s (coefficient of variation, 4.0-6.4%; Pearson's correlation, 0.8-0.95). The present results showed that the use of a metronome and a measurement tape may be a valid method to estimate the mean velocity of execution during the bench press exercise. This simple method could help coaches and athletes achieve their strength training goals, which are partly determined by lifting velocity.

Introducing a novel gravitation-based high-velocity compaction analysis method for pharmaceutical powders.

Science.gov (United States)

Tanner, Timo; Antikainen, Osmo; Ehlers, Henrik; Yliruusi, Jouko

2017-06-30

With modern tableting machines large amounts of tablets are produced with high output. Consequently, methods to examine powder compression in a high-velocity setting are in demand. In the present study, a novel gravitation-based method was developed to examine powder compression. A steel bar is dropped on a punch to compress microcrystalline cellulose and starch samples inside the die. The distance of the bar is being read by a high-accuracy laser displacement sensor which provides a reliable distance-time plot for the bar movement. In-die height and density of the compact can be seen directly from this data, which can be examined further to obtain information on velocity, acceleration and energy distribution during compression. The energy consumed in compact formation could also be seen. Despite the high vertical compression speed, the method was proven to be cost-efficient, accurate and reproducible. Copyright © 2017 Elsevier B.V. All rights reserved.

The PDF4LHC report on PDFs and LHC data: Results from Run I and preparation for Run II

CERN Document Server

Rojo, Juan; Ball, Richard D; Cooper-Sarkar, Amanda; de Roeck, Albert; Farry, Stephen; Ferrando, James; Forte, Stefano; Gao, Jun; Harland-Lang, Lucian; Huston, Joey; Glazov, Alexander; Gouzevitch, Maxime; Gwenlan, Claire; Lipka, Katerina; Lisovyi, Mykhailo; Mangano, Michelangelo; Nadolsky, Pavel; Perrozzi, Luca; Placakyte, Ringaile; Radescu, Voica; Salam, Gavin P; Thorne, Robert

2015-01-01

The accurate determination of the Parton Distribution Functions (PDFs) of the proton is an essential ingredient of the Large Hadron Collider (LHC) program. PDF uncertainties impact a wide range of processes, from Higgs boson characterisation and precision Standard Model measurements to New Physics searches. A major recent development in modern PDF analyses has been to exploit the wealth of new information contained in precision measurements from the LHC Run I, as well as progress in tools and methods to include these data in PDF fits. In this report we summarise the information that PDF-sensitive measurements at the LHC have provided so far, and review the prospects for further constraining PDFs with data from the recently started Run II. This document aims to provide useful input to the LHC collaborations to prioritise their PDF-sensitive measurements at Run II, as well as a comprehensive reference for the PDF-fitting collaborations.

The PDF4LHC report on PDFs and LHC data. Results from Run I and preparation for Run II

International Nuclear Information System (INIS)

Rojo, Juan; Ball, Richard D.; CERN, Geneva

2015-07-01

The accurate determination of the Parton Distribution Functions (PDFs) of the proton is an essential ingredient of the Large Hadron Collider (LHC) program. PDF uncertainties impact a wide range of processes, from Higgs boson characterisation and precision Standard Model measurements to New Physics searches. A major recent development in modern PDF analyses has been to exploit the wealth of new information contained in precision measurements from the LHC Run I, as well as progress in tools and methods to include these data in PDF fits. In this report we summarise the information that PDF-sensitive measurements at the LHC have provided so far, and review the prospects for further constraining PDFs with data from the recently started Run II. This document aims to provide useful input to the LHC collaborations to prioritise their PDF-sensitive measurements at Run II, as well as a comprehensive reference for the PDF-fitting collaborations.

PDF and cAMP enhance PER stability in Drosophila clock neurons

Science.gov (United States)

Li, Yue; Guo, Fang; Shen, James; Rosbash, Michael

2014-01-01

The neuropeptide PDF is important for Drosophila circadian rhythms: pdf01 (pdf-null) animals are mostly arrhythmic or short period in constant darkness and have an advanced activity peak in light–dark conditions. PDF contributes to the amplitude, synchrony, as well as the pace of circadian rhythms within clock neurons. PDF is known to increase cAMP levels in PDR receptor (PDFR)-containing neurons. However, there is no known connection of PDF or of cAMP with the Drosophila molecular clockworks. We discovered that the mutant period gene perS ameliorates the phenotypes of pdf-null flies. The period protein (PER) is a well-studied repressor of clock gene transcription, and the perS protein (PERS) has a markedly short half-life. The result therefore suggests that the PDF-mediated increase in cAMP might lengthen circadian period by directly enhancing PER stability. Indeed, increasing cAMP levels and cAMP-mediated protein kinase A (PKA) activity stabilizes PER, in S2 tissue culture cells and in fly circadian neurons. Adding PDF to fly brains in vitro has a similar effect. Consistent with these relationships, a light pulse causes more prominent PER degradation in pdf01 circadian neurons than in wild-type neurons. The results indicate that PDF contributes to clock neuron synchrony by increasing cAMP and PKA, which enhance PER stability and decrease clock speed in intrinsically fast-paced PDFR-containing clock neurons. We further suggest that the more rapid degradation of PERS bypasses PKA regulation and makes the pace of clock neurons more uniform, allowing them to avoid much of the asynchrony caused by the absence of PDF. PMID:24707054

Application of the Spatial Auto-Correlation Method for Shear-Wave Velocity Studies Using Ambient Noise

Science.gov (United States)

Asten, M. W.; Hayashi, K.

2018-05-01

Ambient seismic noise or microtremor observations used in spatial auto-correlation (SPAC) array methods consist of a wide frequency range of surface waves from the frequency of about 0.1 Hz to several tens of Hz. The wavelengths (and hence depth sensitivity of such surface waves) allow determination of the site S-wave velocity model from a depth of 1 or 2 m down to a maximum of several kilometres; it is a passive seismic method using only ambient noise as the energy source. Application usually uses a 2D seismic array with a small number of seismometers (generally between 2 and 15) to estimate the phase velocity dispersion curve and hence the S-wave velocity depth profile for the site. A large number of methods have been proposed and used to estimate the dispersion curve; SPAC is the one of the oldest and the most commonly used methods due to its versatility and minimal instrumentation requirements. We show that direct fitting of observed and model SPAC spectra generally gives a superior bandwidth of useable data than does the more common approach of inversion after the intermediate step of constructing an observed dispersion curve. Current case histories demonstrate the method with a range of array types including two-station arrays, L-shaped multi-station arrays, triangular and circular arrays. Array sizes from a few metres to several-km in diameter have been successfully deployed in sites ranging from downtown urban settings to rural and remote desert sites. A fundamental requirement of the method is the ability to average wave propagation over a range of azimuths; this can be achieved with either or both of the wave sources being widely distributed in azimuth, and the use of a 2D array sampling the wave field over a range of azimuths. Several variants of the method extend its applicability to under-sampled data from sparse arrays, the complexity of multiple-mode propagation of energy, and the problem of precise estimation where array geometry departs from an

Fulltext PDF

Indian Academy of Sciences (India)

Scholars and Post-Doctoral Fellows (PDF), who work in topology and related areas also to apply. The course consists lectures on the following topics: (a) topology of metric spaces, (b) basic proper- ties of topological spaces, (c) separation axioms and metrization theorems, (d) fundamental groups,. (e) covering spaces and ...

SU-F-T-94: Plan2pdf - a Software Tool for Automatic Plan Report for Philips Pinnacle TPS

Energy Technology Data Exchange (ETDEWEB)

Wu, C [Sutter Medical Foundation, Roseville, CA (United States)

2016-06-15

Purpose: To implement an automatic electronic PDF plan reporting tool for Philips Pinnacle treatment planning system (TPS) Methods: An electronic treatment plan reporting software is developed by us to enable fully automatic PDF report from Pinnacle TPS to external EMR programs such as MOSAIQ. The tool is named “plan2pdf”. plan2pdf is implemented using Pinnacle scripts, Java and UNIX shell scripts, without any external program needed. plan2pdf supports full auto-mode and manual mode reporting. In full auto-mode, with a single mouse click, plan2pdf will generate a detailed Pinnacle plan report in PDF format, which includes customizable cover page, Pinnacle plan summary, orthogonal views through each plan POI and maximum dose point, DRR for each beam, serial transverse views captured throughout the dose grid at a user specified interval, DVH and scorecard windows. The final PDF report is also automatically bookmarked for each section above for convenient plan review. The final PDF report can either be saved on a user specified folder on Pinnacle, or it can be automatically exported to an EMR import folder via a user configured FTP service. In manual capture mode, plan2pdf allows users to capture any Pinnacle plan by full screen, individual window or rectangular ROI drawn on screen. Furthermore, to avoid possible patients’ plan mix-up during auto-mode reporting, a user conflict check feature is included in plan2pdf: it prompts user to wait if another patient is being exported by plan2pdf by another user. Results: plan2pdf is tested extensively and successfully at our institution consists of 5 centers, 15 dosimetrists and 10 physicists, running Pinnacle version 9.10 on Enterprise servers. Conclusion: plan2pdf provides a highly efficient, user friendly and clinical proven platform for all Philips Pinnacle users, to generate a detailed plan report in PDF format for external EMR systems.

SU-F-T-94: Plan2pdf - a Software Tool for Automatic Plan Report for Philips Pinnacle TPS

International Nuclear Information System (INIS)

Wu, C

2016-01-01

Purpose: To implement an automatic electronic PDF plan reporting tool for Philips Pinnacle treatment planning system (TPS) Methods: An electronic treatment plan reporting software is developed by us to enable fully automatic PDF report from Pinnacle TPS to external EMR programs such as MOSAIQ. The tool is named “plan2pdf”. plan2pdf is implemented using Pinnacle scripts, Java and UNIX shell scripts, without any external program needed. plan2pdf supports full auto-mode and manual mode reporting. In full auto-mode, with a single mouse click, plan2pdf will generate a detailed Pinnacle plan report in PDF format, which includes customizable cover page, Pinnacle plan summary, orthogonal views through each plan POI and maximum dose point, DRR for each beam, serial transverse views captured throughout the dose grid at a user specified interval, DVH and scorecard windows. The final PDF report is also automatically bookmarked for each section above for convenient plan review. The final PDF report can either be saved on a user specified folder on Pinnacle, or it can be automatically exported to an EMR import folder via a user configured FTP service. In manual capture mode, plan2pdf allows users to capture any Pinnacle plan by full screen, individual window or rectangular ROI drawn on screen. Furthermore, to avoid possible patients’ plan mix-up during auto-mode reporting, a user conflict check feature is included in plan2pdf: it prompts user to wait if another patient is being exported by plan2pdf by another user. Results: plan2pdf is tested extensively and successfully at our institution consists of 5 centers, 15 dosimetrists and 10 physicists, running Pinnacle version 9.10 on Enterprise servers. Conclusion: plan2pdf provides a highly efficient, user friendly and clinical proven platform for all Philips Pinnacle users, to generate a detailed plan report in PDF format for external EMR systems.

Local Doppler Effect, Index of Refraction through the Earth Crust, PDF and the CNGS Neutrino Anomaly?

Directory of Open Access Journals (Sweden)

Assis A. V. D. B.

2012-04-01

Full Text Available In this brief paper, we show the neutrino velocity discrepancy obtained in the OPERA experiment may be due to the local Doppler effect between a local clock attached to a given detector at Gran Sasso, say C G , and the respective instantaneous clock crossing C G , say C C , being this latter at rest in the instantaneous inertial frame having got the velocity of rotation of CERN about Earth’s axis in relation to the fixed stars. With this effect, the index of refraction of the Earth crust may accomplish a refractive effect by which the neutrino velocity through the Earth crust turns out to be small in relation to the speed of light in the empty space, leading to an encrusted discrepancy that may have contamined the data obtained from the block of detectors at Gran Sasso, leading to a time interval excess that did not provide an exact match between the shift of the protons PDF (probability distribution function by TOF c and the detection data at Gran Sasso via the maximum likelihood matching.

Determination of groundwater flow velocity by radon measurements

International Nuclear Information System (INIS)

Hohn, E.; von Gunten, H.R.

1990-01-01

The groundwater resources of glacio-fluvial perialpine valleys are recharged significantly by the infiltration from rivers. The groundwater residence times between rivers and wells should be known in groundwater management problems. Short residence times can be estimated using radon. Radon concentrations in rivers are usually very low. Upon filtration and movement of the water in the ground, radon is picked up and its concentration increases by 2-3 orders of magnitude according to radioactive growth laws. Residence times and flow velocities can be estimated from the increasing radon concentrations measured in groundwater sampling tubes at different distances from the river. Results obtained with this method agree with the results from experiments with artificial tracers

Differences in the Load-Velocity Profile Between 4 Bench-Press Variants.

Science.gov (United States)

García-Ramos, Amador; Pestaña-Melero, Francisco Luis; Pérez-Castilla, Alejandro; Rojas, Francisco Javier; Haff, Guy Gregory

2018-03-01

To compare the load-velocity relationship between 4 variants of the bench-press (BP) exercise. The full load-velocity relationship of 30 men was evaluated by means of an incremental loading test starting at 17 kg and progressing to the individual 1-repetition maximum (1RM) in 4 BP variants: concentric-only BP, concentric-only BP throw (BPT), eccentric-concentric BP, and eccentric-concentric BPT. A strong and fairly linear relationship between mean velocity (MV) and %1RM was observed for the 4 BP variants (r 2  > .96 for pooled data and r 2  > .98 for individual data). The MV associated with each %1RM was significantly higher in the eccentric-concentric technique than in the concentric-only technique. The only significant difference between the BP and BPT variants was the higher MV with the light to moderate loads (20-70%1RM) in the BPT using the concentric-only technique. MV was significantly and positively correlated between the 4 BP variants (r = .44-.76), which suggests that the subjects with higher velocities for each %1RM in 1 BP variant also tend to have higher velocities for each %1RM in the 3 other BP variants. These results highlight the need for obtaining specific equations for each BP variant and the existence of individual load-velocity profiles.

A single-probe heat pulse method for estimating sap velocity in trees.

Science.gov (United States)

López-Bernal, Álvaro; Testi, Luca; Villalobos, Francisco J

2017-10-01

Available sap flow methods are still far from being simple, cheap and reliable enough to be used beyond very specific research purposes. This study presents and tests a new single-probe heat pulse (SPHP) method for monitoring sap velocity in trees using a single-probe sensor, rather than the multi-probe arrangements used up to now. Based on the fundamental conduction-convection principles of heat transport in sapwood, convective velocity (V h ) is estimated from the temperature increase in the heater after the application of a heat pulse (ΔT). The method was validated against measurements performed with the compensation heat pulse (CHP) technique in field trees of six different species. To do so, a dedicated three-probe sensor capable of simultaneously applying both methods was produced and used. Experimental measurements in the six species showed an excellent agreement between SPHP and CHP outputs for moderate to high flow rates, confirming the applicability of the method. In relation to other sap flow methods, SPHP presents several significant advantages: it requires low power inputs, it uses technically simpler and potentially cheaper instrumentation, the physical damage to the tree is minimal and artefacts caused by incorrect probe spacing and alignment are removed. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

A two pressure-velocity approach for immersed boundary methods in three dimensional incompressible flows

International Nuclear Information System (INIS)

Sabir, O; Ahmad, Norhafizan; Nukman, Y; Tuan Ya, T M Y S

2013-01-01

This paper describes an innovative method for computing fluid solid interaction using Immersed boundary methods with two stage pressure-velocity corrections. The algorithm calculates the interactions between incompressible viscous flows and a solid shape in three-dimensional domain. The fractional step method is used to solve the Navier-Stokes equations in finite difference schemes. Most of IBMs are concern about exchange of the momentum between the Eulerian variables (fluid) and the Lagrangian nodes (solid). To address that concern, a new algorithm to correct the pressure and the velocity using Simplified Marker and Cell method is added. This scheme is applied on staggered grid to simulate the flow past a circular cylinder and study the effect of the new stage on calculations cost. To evaluate the accuracy of the computations the results are compared with the previous software results. The paper confirms the capacity of new algorithm for accurate and robust simulation of Fluid Solid Interaction with respect to pressure field

The analysis of coolant-velocity distribution in plat-typed fuel element using CFD method for RSG-GAS research reactor

International Nuclear Information System (INIS)

Muhammad Subekti; Darwis Isnaini; Endiah Puji Hastuti

2013-01-01

The measurement experiment for coolant-velocity distribution in the subchannel of fuel element of RSG-GAS research reactor is difficult to be carried out due to too narrow channel and subchannel placed inside the fuel element. Hence, the calculation is required to predict the coolant-velocity distribution inside subchannel to confirm that the handle presence does not ruin the velocity distribution into every subchannel. This calculation utilizes CFD method, which respect to 3-dimension interior. Moreover, the calculation of coolant-velocity distribution inside subchannel was not ever carried out. The research object is to investigate the distribution of coolant-velocity in plat-typed fuel element using 3-dimension CFD method for RSG-GAS research reactor. This research is required as a part of the development of thermalhydraulic design of fuel element for innovative research reactor as well. The modeling uses ½ model in Gambit software and calculation uses turbulence equation in FLUENT 6.3 software. Calculation result of 3D coolant-velocity in subchannel using CFD method is lower about 4.06 % than 1D calculation result due to 1D calculation obeys handle availability. (author)

The PDF4LHC report on PDFs and LHC data: results from Run I and preparation for Run II

International Nuclear Information System (INIS)

Rojo, Juan; Accardi, Alberto; Ball, Richard D; Cooper-Sarkar, Amanda; Gwenlan, Claire; Roeck, Albert de; Mangano, Michelangelo; Farry, Stephen; Ferrando, James; Forte, Stefano; Gao, Jun; Harland-Lang, Lucian; Huston, Joey; Glazov, Alexander; Lipka, Katerina; Gouzevitch, Maxime; Lisovyi, Mykhailo; Nadolsky, Pavel

2015-01-01

The accurate determination of the parton distribution functions (PDFs) of the proton is an essential ingredient of the Large Hadron Collider (LHC) program. PDF uncertainties impact a wide range of processes, from Higgs boson characterization and precision Standard Model measurements to new physics searches. A major recent development in modern PDF analyses has been to exploit the wealth of new information contained in precision measurements from the LHC Run I, as well as progress in tools and methods to include these data in PDF fits. In this report we summarize the information that PDF-sensitive measurements at the LHC have provided so far, and review the prospects for further constraining PDFs with data from the recently started Run II. This document aims to provide useful input to the LHC collaborations to prioritize their PDF-sensitive measurements at Run II, as well as a comprehensive reference for the PDF-fitting collaborations. (topical review)

Bulk velocity extraction for nano-scale Newtonian flows

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wenfei, E-mail: zwenfei@gmail.com [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China); Sun, Hongyu [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China)

2012-04-16

The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

Bulk velocity extraction for nano-scale Newtonian flows

International Nuclear Information System (INIS)

Zhang, Wenfei; Sun, Hongyu

2012-01-01

The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

Fulltext PDF

Indian Academy of Sciences (India)

ways to track turtles both through space and time. The comparison of ... as a single nesting population was reduced to a few hundred individuals in the 1970s. However .... turtles spent some part of the year in those coastal waters. However ..... The newsletters are available online in PDF format and a limited number of.

The velocity of sound

International Nuclear Information System (INIS)

Beyer, R.T.

1985-01-01

The paper reviews the work carried out on the velocity of sound in liquid alkali metals. The experimental methods to determine the velocity measurements are described. Tables are presented of reported data on the velocity of sound in lithium, sodium, potassium, rubidium and caesium. A formula is given for alkali metals, in which the sound velocity is a function of shear viscosity, atomic mass and atomic volume. (U.K.)

Direct photon production and PDF fits reloaded

NARCIS (Netherlands)

Campbell, John M.; Rojo, Juan; Slade, Emma; Williams, Ciaran

2018-01-01

Direct photon production in hadronic collisions provides a handle on the gluon PDF by means of the QCD Compton scattering process. In this work we revisit the impact of direct photon production on a global PDF analysis, motivated by the recent availability of the next-to-next-to-leading (NNLO)

Online Wavelet Complementary velocity Estimator.

Science.gov (United States)

Righettini, Paolo; Strada, Roberto; KhademOlama, Ehsan; Valilou, Shirin

2018-02-01

In this paper, we have proposed a new online Wavelet Complementary velocity Estimator (WCE) over position and acceleration data gathered from an electro hydraulic servo shaking table. This is a batch estimator type that is based on the wavelet filter banks which extract the high and low resolution of data. The proposed complementary estimator combines these two resolutions of velocities which acquired from numerical differentiation and integration of the position and acceleration sensors by considering a fixed moving horizon window as input to wavelet filter. Because of using wavelet filters, it can be implemented in a parallel procedure. By this method the numerical velocity is estimated without having high noise of differentiators, integration drifting bias and with less delay which is suitable for active vibration control in high precision Mechatronics systems by Direct Velocity Feedback (DVF) methods. This method allows us to make velocity sensors with less mechanically moving parts which makes it suitable for fast miniature structures. We have compared this method with Kalman and Butterworth filters over stability, delay and benchmarked them by their long time velocity integration for getting back the initial position data. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

On the importance of effective convergence velocity of synthetic acceleration methods in neutron transport

International Nuclear Information System (INIS)

Coppa, G.G.M.; Ravetto, P.; Colombo, V.

1996-01-01

The present work concerns some aspects of the optimization of the synthesis acceleration techniques in neutron transport. The importance of non-asymptotic convergence velocity as a theoretical means to characterize and optimize acceleration methods is discussed in detail for isotropic as well as highly anisotropic scattering cases; this shows the innacuracy of results based only on the usual asyptotic analysis. A detailed study of convergence velocity behaviour for space discretized schemes and multidimensional problems is also presented. Finally, various kinds of theoretical-evaluated convergence velocities are reported to study the effective behaviour of some modifications of the classic DSA technique recently proposed to face its loss of effectiveness and optimize performances when dealing with highly anisotropic scattering; comparisons with results of already assessed DSA modification techniques are reported for various scattering cross-section configurations. (Author)

New frontiers in PDF determination

CERN Multimedia

CERN. Geneva

2016-01-01

Parton Distribution Functions (PDFs) are a crucial input at the LHC, their uncertainty often being the limiting factor in the accuracy of theoretical predictions. At the same time the LHC is delivering a number of precise measurements that have the potential to greatly constrain these functions. I will give an overview on the theory behind and on the state of the art of PDF determination. I will then mention the new theoretical and methodological challenges in modern PDF fits and explore the precision frontiers opened by the accuracy of the LHC data.

Analysis of flexible-membrane aerofoils by a method of velocity singularities

International Nuclear Information System (INIS)

Mateescu, D.; Newman, B.G.

1985-01-01

Two dimensional sails were originally treated as flexible, impervious, inextensible membranes. These methods are developed in the context of thin aerofoil theory, the membrane being replaced by a vortex sheet and the boundary conditions satisfied at the corresponding positions on the aerofoil chord. The present present methos is developed as a linear potential theory, although it may be further extended to include non-linear and viscous effects. The new analysis is based on the method of velocity singularities associated with the changes in aerofoil slope developed for rigid aerofoils; it eliminates the need of formally solving an integral equation

Modeling of the Maximum Entropy Problem as an Optimal Control Problem and its Application to Pdf Estimation of Electricity Price

Directory of Open Access Journals (Sweden)

M. E. Haji Abadi

2013-09-01

Full Text Available In this paper, the continuous optimal control theory is used to model and solve the maximum entropy problem for a continuous random variable. The maximum entropy principle provides a method to obtain least-biased probability density function (Pdf estimation. In this paper, to find a closed form solution for the maximum entropy problem with any number of moment constraints, the entropy is considered as a functional measure and the moment constraints are considered as the state equations. Therefore, the Pdf estimation problem can be reformulated as the optimal control problem. Finally, the proposed method is applied to estimate the Pdf of the hourly electricity prices of New England and Ontario electricity markets. Obtained results show the efficiency of the proposed method.

Assessment of PDF Micromixing Models Using DNS Data for a Two-Step Reaction

Science.gov (United States)

Tsai, Kuochen; Chakrabarti, Mitali; Fox, Rodney O.; Hill, James C.

1996-11-01

Although the probability density function (PDF) method is known to treat the chemical reaction terms exactly, its application to turbulent reacting flows have been overshadowed by the ability to model the molecular mixing terms satisfactorily. In this study, two PDF molecular mixing models, the linear-mean-square-estimation (LMSE or IEM) model and the generalized interaction-by-exchange-with-the-mean (GIEM) model, are compared with the DNS data in decaying turbulence with a two-step parallel-consecutive reaction and two segregated initial conditions: ``slabs" and ``blobs". Since the molecular mixing model is expected to have a strong effect on the mean values of chemical species under such initial conditions, the model evaluation is intended to answer the following questions: Can the PDF models predict the mean values of chemical species correctly with completely segregated initial conditions? (2) Is a single molecular mixing timescale sufficient for the PDF models to predict the mean values with different initial conditions? (3) Will the chemical reactions change the molecular mixing timescales of the reacting species enough to affect the accuracy of the model's prediction for the mean values of chemical species?

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Indian Academy of Sciences (India)

Energy Fit with the Local Correlation Tracking and Doppler Velocity. B. Ravindra. ∗. & D. W. Longcope ... In the solar photosphere, it is now possible to measure all the components of the mag- netic field with some ... Longcope (2004) developed a method, the minimum energy fit (MEF) which uses the induction equation and ...

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Indian Academy of Sciences (India)

Admin

B ackground. T he sub-title of this article is borrow ed from tw o dis- ..... theory w hich so starkly opposed the B iblicalversion of creation. A second .... R eca p itu la - tion and C onclusion, sum m arises the thesis { w hich, in ...... Education, 2002; http://www.muslimheritage.com/uploads/ibnsina.pdf) for an early example of ...

Numerical simulation of a plane turbulent mixing layer, with applications to isothermal, rapid reactions

Science.gov (United States)

Lin, P.; Pratt, D. T.

1987-01-01

A hybrid method has been developed for the numerical prediction of turbulent mixing in a spatially-developing, free shear layer. Most significantly, the computation incorporates the effects of large-scale structures, Schmidt number and Reynolds number on mixing, which have been overlooked in the past. In flow field prediction, large-eddy simulation was conducted by a modified 2-D vortex method with subgrid-scale modeling. The predicted mean velocities, shear layer growth rates, Reynolds stresses, and the RMS of longitudinal velocity fluctuations were found to be in good agreement with experiments, although the lateral velocity fluctuations were overpredicted. In scalar transport, the Monte Carlo method was extended to the simulation of the time-dependent pdf transport equation. For the first time, the mixing frequency in Curl's coalescence/dispersion model was estimated by using Broadwell and Breidenthal's theory of micromixing, which involves Schmidt number, Reynolds number and the local vorticity. Numerical tests were performed for a gaseous case and an aqueous case. Evidence that pure freestream fluids are entrained into the layer by large-scale motions was found in the predicted pdf. Mean concentration profiles were found to be insensitive to Schmidt number, while the unmixedness was higher for higher Schmidt number. Applications were made to mixing layers with isothermal, fast reactions. The predicted difference in product thickness of the two cases was in reasonable quantitative agreement with experimental measurements.

Measurement of the burning velocity of propane-air mixtures using soap bubbles

Energy Technology Data Exchange (ETDEWEB)

Sakai, Yukio

1988-12-20

By filling a soap bubble with propane-air mixture of spacified equivalence ratio and by igniting it at the center, the flame propagation velocity was measured applying multiplex exposure Schlieren method. And the flow velocity of the unburnt propane-air mixture was also measured by a hot-wire anemometer. From the differences of the above two velocities, the burning velocity was obtained. The values of the burning velocity agreed well with the highly accurate results of usual measurements. The maximum value of the burning velocity, which exists at an equivalence ratio of 1.1, was 50cm/s. This value agreed well with the theoretical calculation result on the on-dimensional flame by Warnatz. The burning velocity in the range of from 0.7 to 1.5 equivalence ratios decreases symmetrically with the maximum value at the center. The velocity decrease in the excessive concentration range of fuel is only a little and converges between 7 and 10 cm/s. To evade the influence of the flame-front instability, measurements were done from 2 to 5cm from the ignition center. Thus accurate values were obtained. 23 refs., 5 figs.

Method of solution for the determination of the velocity profiles in turbulent flow through annular tobes

Energy Technology Data Exchange (ETDEWEB)

Schmal, M; Russo, Q [Rio de Janeiro Univ. (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Almeida, M S; Bozzo, S [Rio de Janeiro Univ. (Brazil). Instituto de Quimica

1975-03-01

A method of solutions is presented for the determination of the velocity profiles in turbulent flow through annular tubes, based on the Von Karman similarity theory developed by Quarmby. The parameters found by Quarmby appearing in the velocity profiles and determined experimentally by different authors were approximated by polynonial functions of variable degree, as function of the Reynolds numbers. The Runge-Kutta-Nystrom method was used in the integration of the differential equations and the systematic of solution is presented in a computer program. The calculated results were compared to the experimental date and presented a deviation of 10/sup -2/%.

Comparison of Effective Medium Schemes For Seismic Velocities in Cracked Anisotropic Rock

Science.gov (United States)

Morshed, S.; Chesnokov, E.

2017-12-01

Understanding of elastic properties of reservoir rock is necessary for meaningful interpretation and analysis of seismic measurements. The elastic properties of a rock are controlled by the microstructural properties such as mineralogical composition, pore and crack distribution, texture and pore connectivity. However, seismic scale is much larger than microstructure scale. Understanding of macroscopic properties at relevant seismic scale (e.g. borehole sonic data) comes from effective medium theory (EMT). However, most of the effective medium theories fail at high crack density as the interactions of strain fields of the cracks can't be ignored. We compare major EMT schemes from low to high crack density. While at low crack density all method gives similar results, at high crack density they differ significantly. Then, we focus on generalized singular approximation (GSA) and effective field (EF) method as they allow cracks beyond the limit of dilute concentrations. Additionally, we use grain contact (GC) method to examine the stiffness constants of the rock matrix. We prepare simple models of a multiphase media containing low to high concentrations of isolated pores. Randomly oriented spherical pores and horizontally oriented ellipsoidal (aspect ratio =0.1) pores have been considered. For isolated spherical pores, all the three methods show exactly same or similar results. However, inclusion interactions are different in different directions in case of horizontal ellipsoidal pores and individual stiffness constants differ greatly from one method to another at different crack density. Stiffness constants remain consistent in GSA method whereas some components become unusual in EF method at a higher crack density (>0.15). Finally, we applied GSA method to interpret ultrasonic velocities of core samples. Mineralogical composition from X-ray diffraction (XRD) data and lab measured porosity data have been utilized. Both compressional and shear wave velocities from GSA

Design and application of PDF model for extracting

Science.gov (United States)

Xiong, Lei

2013-07-01

In order to change the steps of contributions in editorial department system from two steps to one, this paper advocates that the technology of extracting the information of PDF files should be transplanted from PDF reader into IEEE Xplore contribution system and that it should be combined with uploading in batch skillfully to enable editors to upload PDF files about 1GB in batch for once. Computers will extract the information of the title, author, address, mailbox, abstract and key words of thesis voluntarily for later retrieval so as to save plenty of labor, material and finance for editorial department.

The determination methods of the velocity constant for electrochemical reactions; Les methodes de determination de la constante de vitesse des reactions electrochimiques

Energy Technology Data Exchange (ETDEWEB)

Molina, R

1963-07-01

In a brief introduction are recalled the fundamental mechanisms of the electrochemical reaction and the definition of the intrinsic velocity constant of a such reaction. By the nature of the different parameters which enter in this definition are due some experimental problems which are examined. Then are given the principles of the measurement methods of the velocity constant. These methods are developed with the mathematical expression of the different rates of the mass transfer to an electrode. In each case are given the experimental limits of use of the methods and the size order of the velocity constant that can be reached. A list of fundamental works to be consulted conclude this work. (O.M.) [French] Dans une breve introduction sont rappeles les mecanismes fondamentaux de la reaction electrochimique et la definition de la constante de vitesse intrinseque d'une telle reaction. De la nature des differents parametres qui entrent dans celle definition, decoulent un certain nombre de problemes experimentaux qui sont passes en revue. On donne ensuite les principes des methodes de mesure de la constante de vitesse. L'exposition de ces methodes est developpee a l'aide de l'expression mathematique des differents regimes de transfert de masse a une electrode. On s'attache dans chaque cas, a donner les limitations experimentales d'utilisation des methodes et l'ordre de grandeur de la constante de vitesse qu'elles permettent d'atteindre. Une liste des ouvrages fondamentaux a consulter conclut ce travail. (auteur)

A method for predicting the impact velocity of a projectile fired from a compressed air gun facility

International Nuclear Information System (INIS)

Attwood, G.J.

1988-03-01

This report describes the development and use of a method for calculating the velocity at impact of a projectile fired from a compressed air gun. The method is based on a simple but effective approach which has been incorporated into a computer program. The method was developed principally for use with the Horizontal Impact Facility at AEE Winfrith but has been adapted so that it can be applied to any compressed air gun of a similar design. The method has been verified by comparison of predicted velocities with test data and the program is currently being used in a predictive manner to specify test conditions for the Horizontal Impact Facility at Winfrith. (author)

Complexity in the scaling of velocity fluctuations in the high-latitude F-region ionosphere

Directory of Open Access Journals (Sweden)

M. L. Parkinson

2008-09-01

Full Text Available The temporal scaling properties of F-region velocity fluctuations, δv_los, were characterised over 17 octaves of temporal scale from τ=1 s to <1 day using a new data base of 1-s time resolution SuperDARN radar measurements. After quality control, 2.9 (1.9 million fluctuations were recorded during 31.5 (40.4 days of discretionary mode soundings using the Tasmanian (New Zealand radars. If the fluctuations were statistically self-similar, the probability density functions (PDFs of δv_los would collapse onto the same PDF using the scaling P_s (δv_s, τ=τ^αP (δv_los, τ and δv_s=δv_losτ^−α where α is the scaling exponent. The variations in scaling exponents α and multi-fractal behaviour were estimated using peak scaling and generalised structure function (GSF analyses, and a new method based upon minimising the differences between re-scaled probability density functions (PDFs. The efficiency of this method enabled calculation of "α spectra", the temporal spectra of scaling exponents from τ=1 s to ~2048 s. The large number of samples enabled calculation of α spectra for data separated into 2-h bins of MLT as well as two main physical regimes: Population A echoes with Doppler spectral width <75 m s⁻¹ concentrated on closed field lines, and Population B echoes with spectral width >150 m s⁻¹ concentrated on open field lines. For all data there was a scaling break at τ~10 s and the similarity of the fluctuations beneath this scale may be related to the large spatial averaging (~100 km×45 km employed by SuperDARN radars. For Tasmania Population B, the velocity fluctuations exhibited approximately mono fractal power law scaling between τ~8 s and 2048 s (34 min, and probably up to several hours. The scaling exponents were generally less than that expected for basic MHD

CAN THE CURRICULUM BE USED TO ESTIMATE CRITICAL VELOCITY IN YOUNG COMPETITIVE SWIMMERS?

Directory of Open Access Journals (Sweden)

Daniel A. Marinho

2009-03-01

Full Text Available The aims of the present study were to assess critical velocity using the swimmer curriculum in front crawl events and to compare critical velocity to the velocity corresponding to a 4 mmol·l-1 of blood lactate concentration and to the velocity of a 30 min test. The sample included 24 high level male swimmers ranged between 14 and 16 years old. For each subject the critical velocity, the velocity corresponding to a 4 mmol·l-1 of blood lactate concentration and the mean velocity of a 30 min test were determined. The critical velocity was also estimated by considering the best performance of a swimmer over several distances based on the swimmer curriculum. Critical velocity including 100, 200 and 400 m events was not different from the velocity of 4 mmol·l-1 of blood lactate concentration. Critical velocity including all the swimmer events was not different from the velocity of a 30 min test. The assessment of critical velocity based upon the swimmer curriculum would therefore seem to be a good approach to determine the aerobic ability of a swimmer. The selection of the events to be included in critical velocity assessment must be a main concern in the evaluation of the swimmer

Correlation of right atrial appendage velocity with left atrial appendage velocity and brain natriuretic Peptide.

Science.gov (United States)

Kim, Bu-Kyung; Heo, Jung-Ho; Lee, Jae-Woo; Kim, Hyun-Soo; Choi, Byung-Joo; Cha, Tae-Joon

2012-03-01

Left atrial appendage (LAA) anatomy and function have been well characterized both in healthy and diseased people, whereas relatively little attention has been focused on the right atrial appendage (RAA). We sought to evaluate RAA flow velocity and to compare these parameters with LAA indices and with a study of biomarkers, such as brain natriuretic peptide, among patients with sinus rhythm (SR) and atrial fibrillation (AF). In a series of 79 consecutive patients referred for transesophageal echocardiography, 43 patients (23 with AF and 20 controls) were evaluated. AF was associated with a decrease in flow velocity for both LAA and RAA [LAA velocity-SR vs. AF: 61 ± 22 vs. 29 ± 18 m/sec (p vs. AF: 46 ± 20 vs. 19 ± 8 m/sec (p brain natriuretic peptide (BNP). AF was associated with decreased RAA and LAA flow velocities. RAA velocity was found to be positively correlated with LAA velocity and negatively correlated with BNP. The plasma BNP concentration may serve as a determinant of LAA and RAA functions.

Numerical modeling of probe velocity effects for electromagnetic NDE methods

Science.gov (United States)

Shin, Y. K.; Lord, W.

The present discussion of magnetic flux (MLF) leakage inspection introduces the behavior of motion-induced currents. The results obtained indicate that velocity effects exist at even low probe speeds for magnetic materials, compelling the inclusion of velocity effects in MLF testing of oil pipelines, where the excitation level and pig speed are much higher than those used in the present work. Probe velocity effect studies should influence probe design, defining suitable probe speed limits and establishing training guidelines for defect-characterization schemes.

Sedimentation Velocity Analysis of Large Oligomeric Chromatin Complexes Using Interference Detection.

Science.gov (United States)

Rogge, Ryan A; Hansen, Jeffrey C

2015-01-01

Sedimentation velocity experiments measure the transport of molecules in solution under centrifugal force. Here, we describe a method for monitoring the sedimentation of very large biological molecular assemblies using the interference optical systems of the analytical ultracentrifuge. The mass, partial-specific volume, and shape of macromolecules in solution affect their sedimentation rates as reflected in the sedimentation coefficient. The sedimentation coefficient is obtained by measuring the solute concentration as a function of radial distance during centrifugation. Monitoring the concentration can be accomplished using interference optics, absorbance optics, or the fluorescence detection system, each with inherent advantages. The interference optical system captures data much faster than these other optical systems, allowing for sedimentation velocity analysis of extremely large macromolecular complexes that sediment rapidly at very low rotor speeds. Supramolecular oligomeric complexes produced by self-association of 12-mer chromatin fibers are used to illustrate the advantages of the interference optics. Using interference optics, we show that chromatin fibers self-associate at physiological divalent salt concentrations to form structures that sediment between 10,000 and 350,000S. The method for characterizing chromatin oligomers described in this chapter will be generally useful for characterization of any biological structures that are too large to be studied by the absorbance optical system. © 2015 Elsevier Inc. All rights reserved.

Fulltext PDF

Indian Academy of Sciences (India)

Sandeep M., Sun F., Liu F., Li J., David P. B. and Yue G. H. 2012 Novel polymorphic microsatellites from Florida red tilapia and cross- species amplification in Mozambique and Nile tilapia. J. Genet. 91, e97–e99. Online only: http://www.ias.ac.in/jgenet/OnlineResources/. 91/e97.pdf. Xin C., Yu D., Peng J., Hu H., Xing Y. and ...

A Electronic Map Data Model Based on PDF

Science.gov (United States)

Zhou, Xiaodong; Yang, Chuncheng; Meng, Nina; Peng, Peng

2018-05-01

In this paper, we proposed the PDFEMAP (PDF electronic map) that is a kind of new electronic map products aiming at the current situation and demand of the use of electronic map products. Firstly gives the definition and characteristics of PDFEMAP, followed by a detailed description of the data model and method for generating PDFEMAP, and finally expounds application modes of the PDFEMAP which feasibility and effectiveness are verified.

Influence of Isoinertial-Pneumatic Mixed Resistances on Force-Velocity Relationship.

Science.gov (United States)

Avrillon, Simon; Jidovtseff, Boris; Hug, François; Guilhem, Gaël

2017-03-01

Muscle strengthening is commonly based on the use of isoinertial loading, whereas variable resistances such as pneumatic loading may be implemented to optimize training stimulus. The purpose of the current study was to determine the effect of the ratio between pneumatic and isoinertial resistance on the force-velocity relationship during ballistic movements. A total of 15 participants performed 2 concentric repetitions of ballistic bench-press movements with intention to throw the bar at 30%, 45%, 60%, 75%, and 90% of the maximal concentric repetition with 5 resistance ratios including 100%, 75%, 50%, 25%, or 0% of pneumatic resistance, the additional load being isoinertial. Force-, velocity-, and power-time patterns were assessed and averaged over the concentric phase to determine the force-velocity and power-velocity relationships for each resistance ratio. Each 25% increase in the pneumatic part in the resistance ratio elicited higher movement velocity (+0.11 ± 0.03 m/s from 0% to 80% of the concentric phase) associated with lower force levels (-43.6 ± 15.2 N). Increased isoinertial part in the resistance ratio resulted in higher velocity toward the end of the movement (+0.23 ± 0.01 m/s from 90% to 100%). The findings show that the resistance ratio could be modulated to develop the acceleration phase and force toward the end of the concentric phase (pneumatic-oriented resistance). Inversely, isoinertial-oriented resistance should be used to develop maximal force and maximal power. Resistance modality could, therefore, be considered an innovative variable to modulate the training stimulus according to athletic purposes.

Monte-Carlo calculation of the calibration factors for the interfacial area concentration and the velocity of the bubbles for double sensor conductivity probe

International Nuclear Information System (INIS)

Munoz-Cobo, J.L.; Pena, J.; Chiva, S.; Mendez, S.

2007-01-01

This paper presents a study of the estimation of the correction factors for the interfacial area concentration and the bubble velocity in two phase flow measurements using the double sensor conductivity probe. Monte-Carlo calculations of these correction factors have been performed for different values of the relative distance (ΔS/D) between the tips of the conductivity probe and different values of the relative bubble velocity fluctuation parameter. Also this paper presents the Monte-Carlo calculation of the expected value of the calibration factors for bubbly flow assuming a log-normal distribution of the bubble sizes. We have computed the variation of the expected values of the calibration factors with the relative distance (ΔS/D) between the tips and the velocity fluctuation parameter. Finally, we have performed a sensitivity study of the variation of the average values of the calibration factors for bubbly flow with the geometrical standard deviation of the log-normal distribution of bubble sizes. The results of these calculations show that the total interfacial area correction factor is very close to 2, and depends very weakly on the velocity fluctuation, and the relative distance between tips. For the velocity calibration factor, the Monte-Carlo results show that for moderate values of the relative bubble velocity fluctuation parameter (H max ≤ 0.3) and values of the relative distance between tips not too small (ΔS/D ≥ 0.2), the correction velocity factor for the bubble sensor conductivity probe is close to unity, ranging from 0.96 to 1

The pdf approach to turbulent polydispersed two-phase flows

Science.gov (United States)

Minier, Jean-Pierre; Peirano, Eric

2001-10-01

The purpose of this paper is to develop a probabilistic approach to turbulent polydispersed two-phase flows. The two-phase flows considered are composed of a continuous phase, which is a turbulent fluid, and a dispersed phase, which represents an ensemble of discrete particles (solid particles, droplets or bubbles). Gathering the difficulties of turbulent flows and of particle motion, the challenge is to work out a general modelling approach that meets three requirements: to treat accurately the physically relevant phenomena, to provide enough information to address issues of complex physics (combustion, polydispersed particle flows, …) and to remain tractable for general non-homogeneous flows. The present probabilistic approach models the statistical dynamics of the system and consists in simulating the joint probability density function (pdf) of a number of fluid and discrete particle properties. A new point is that both the fluid and the particles are included in the pdf description. The derivation of the joint pdf model for the fluid and for the discrete particles is worked out in several steps. The mathematical properties of stochastic processes are first recalled. The various hierarchies of pdf descriptions are detailed and the physical principles that are used in the construction of the models are explained. The Lagrangian one-particle probabilistic description is developed first for the fluid alone, then for the discrete particles and finally for the joint fluid and particle turbulent systems. In the case of the probabilistic description for the fluid alone or for the discrete particles alone, numerical computations are presented and discussed to illustrate how the method works in practice and the kind of information that can be extracted from it. Comments on the current modelling state and propositions for future investigations which try to link the present work with other ideas in physics are made at the end of the paper.

Errors analysis in the evaluation of particle concentration by PDA on a turbulent two-phase jet: application for cross section and transit time methods

Energy Technology Data Exchange (ETDEWEB)

Calvo, Esteban; Garcia, Juan A.; Garcia, Ignacio; Aisa, Luis A. [University of Zaragoza, Area de Mecanica de Fluidos, Centro Politecnico Superior, Zaragoza (Spain)

2009-09-15

Phase-Doppler anemometry (PDA) is a powerful tool for two-phase flow measurements and testing. Particle concentration and mass flux can also be evaluated using the raw particle data supplied by this technique. The calculation starts from each particle velocity, diameter, transit time data, and the total measurement time. There are two main evaluation strategies. The first one uses the probe volume effective cross section, and it is usually simplified assuming that particles follow quasi one-directional trajectories. In the text, it will be called the cross section method. The second one includes a set of methods which will be denoted as ''Generalized Integral Methods'' (GIM). Concentration algorithms such as the transit time method (TTM) and the integral volume method (IVM) are particular cases of the GIM. In any case, a previous calibration of the measurement volume geometry is necessary to apply the referred concentration evaluation methods. In this study, concentrations and mass fluxes both evaluated by the cross-section method and the TTM are compared. Experimental data are obtained from a particle-laden jet generated by a convergent nozzle. Errors due to trajectory dispersion, burst splitting, and multi-particle signals are discussed. (orig.)

Development of the interfacial area concentration measurement method using a five sensor conductivity probe

International Nuclear Information System (INIS)

Euh, Dong Jin; Yun, Byong Jo; Song, Chul Hwa; Kwon, Tae Soon; Chung, Moon Ki; Lee, Un Chul

2000-01-01

The interfacial area concentration(IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAE can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly than the four sensor prober. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator

PDF added value of a high resolution climate simulation for precipitation

Science.gov (United States)

Soares, Pedro M. M.; Cardoso, Rita M.

2015-04-01

General Circulation Models (GCMs) are models suitable to study the global atmospheric system, its evolution and response to changes in external forcing, namely to increasing emissions of CO2. However, the resolution of GCMs, of the order of 1o, is not sufficient to reproduce finer scale features of the atmospheric flow related to complex topography, coastal processes and boundary layer processes, and higher resolution models are needed to describe observed weather and climate. The latter are known as Regional Climate Models (RCMs) and are widely used to downscale GCMs results for many regions of the globe and are able to capture physically consistent regional and local circulations. Most of the RCMs evaluations rely on the comparison of its results with observations, either from weather stations networks or regular gridded datasets, revealing the ability of RCMs to describe local climatic properties, and assuming most of the times its higher performance in comparison with the forcing GCMs. The additional climatic details given by RCMs when compared with the results of the driving models is usually named as added value, and it's evaluation is still scarce and controversial in the literuature. Recently, some studies have proposed different methodologies to different applications and processes to characterize the added value of specific RCMs. A number of examples reveal that some RCMs do add value to GCMs in some properties or regions, and also the opposite, elighnening that RCMs may add value to GCM resuls, but improvements depend basically on the type of application, model setup, atmospheric property and location. The precipitation can be characterized by histograms of daily precipitation, or also known as probability density functions (PDFs). There are different strategies to evaluate the quality of both GCMs and RCMs in describing the precipitation PDFs when compared to observations. Here, we present a new method to measure the PDF added value obtained from

An evaluation method of critical velocity for self-excited vibration of cross-shaped tube bundle in cross flow

International Nuclear Information System (INIS)

Inada, Fumio; Nishihara, Takashi; Yasuo, Akira; Morita, Ryo

2002-01-01

The applicability of the cross-shaped tube bundle as a lower plenum component of pressure vessel is examined to develop a next generation LWR in Japanese electric utilities. The flow-induced vibration characteristics are not understood well. Methods to evaluate turbulence induced vibration and vortex induced vibration were proposed by CRIEPI. In this study, vibration response is obtained experimentally to propose a method to evaluate self-excited vibration of cross-shaped tube bundle. The self-excited vibration was found to be generated when nondimensional flow velocity was above a critical value. The nondimensional critical velocity of normal configuration is 15% smaller than that of staggered configuration, which means that the nondimensional critical velocity of normal configuration can give conservative evaluation. The result of Reynolds number Re=6.2 x 10 4 agrees well with that of Re=6.8 x 10 5 , in which region, the effect of Reynolds number on the critical velocity is small. (author)

Dynamic Link Inclusion in Online PDF Journals

OpenAIRE

Probets, Steve; Brailsford, David; Carr, Les; Hall, Wendy

1998-01-01

Two complementary de facto standards for the publication of electronic documents are HTML on theWorldWideWeb and Adobe s PDF (Portable Document Format) language for use with Acrobat viewers. Both these formats provide support for hypertext features to be embedded within documents. We present a method, which allows links and other hypertext material to be kept in an abstract form in separate link databases. The links can then be interpreted or compiled at any stage and applied, in the correct ...

Modified method of perturbed stationary states. II. Semiclassical and low-velocity quantal approximations

International Nuclear Information System (INIS)

Green, T.A.

1978-10-01

For one-electron heteropolar systems, the wave-theoretic Lagrangian of Paper I 2 is simplified in two distinct approximations. The first is semiclassical; the second is quantal, for velocities below those for which the semiclassical treatment is reliable. For each approximation, unitarity and detailed balancing are discussed. Then, the variational method as described by Demkov is used to determine the coupled equations for the radial functions and the Euler-Lagrange equations for the translational factors which are part of the theory. Specific semiclassical formulae for the translational factors are given in a many-state approximation. Low-velocity quantal formulae are obtained in a one-state approximation. The one-state results of both approximations agree with an earlier determination by Riley. 14 references

Simultaneous velocity and pressure quantification using pressure-sensitive flow tracers in air

Science.gov (United States)

Zhang, Peng; Peterson, Sean; Porfiri, Maurizio

2017-11-01

Particle-based measurement techniques for assessing the velocity field of a fluid have advanced rapidly over the past two decades. Full-field pressure measurement techniques have remained elusive, however. In this work, we aim to demonstrate the possibility of direct simultaneous planar velocity and pressure measurement of a high speed aerodynamic flow by employing novel pressure-sensitive tracer particles for particle image velocimetry (PIV). Specifically, the velocity and pressure variations of an airflow through a converging-diverging channel are studied. Polystyrene microparticles embedded with a pressure-sensitive phosphorescent dye-platinum octaethylporphyrin (PtOEP)-are used as seeding particles. Due to the oxygen quenching effect, the emission lifetime of PtOEP is highly sensitive to the oxygen concentration, that is, the partial pressure of oxygen, in the air. Since the partial pressure of oxygen is linearly proportional to the air pressure, we can determine the air pressure through the phosphorescence emission lifetime of the dye. The velocity field is instead obtained using traditional PIV methods. The particles have a pressure resolution on the order of 1 kPa, which may be improved by optimizing the particle size and dye concentration to suit specific flow scenarios. This work was supported by the National Science Foundation under Grant Number CBET-1332204.

MRI contrast agent concentration and tumor interstitial fluid pressure.

Science.gov (United States)

Liu, L J; Schlesinger, M

2016-10-07

The present work describes the relationship between tumor interstitial fluid pressure (TIFP) and the concentration of contrast agent for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). We predict the spatial distribution of TIFP based on that of contrast agent concentration. We also discuss the cases for estimating tumor interstitial volume fraction (void fraction or porosity of porous medium), ve, and contrast volume transfer constant, K(trans), by measuring the ratio of contrast agent concentration in tissue to that in plasma. A linear fluid velocity distribution may reflect a quadratic function of TIFP distribution and lead to a practical method for TIFP estimation. To calculate TIFP, the parameters or variables should preferably be measured along the direction of the linear fluid velocity (this is in the same direction as the gray value distribution of the image, which is also linear). This method may simplify the calculation for estimating TIFP. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Straight velocity boundaries in the lattice Boltzmann method

Science.gov (United States)

Latt, Jonas; Chopard, Bastien; Malaspinas, Orestis; Deville, Michel; Michler, Andreas

2008-05-01

Various ways of implementing boundary conditions for the numerical solution of the Navier-Stokes equations by a lattice Boltzmann method are discussed. Five commonly adopted approaches are reviewed, analyzed, and compared, including local and nonlocal methods. The discussion is restricted to velocity Dirichlet boundary conditions, and to straight on-lattice boundaries which are aligned with the horizontal and vertical lattice directions. The boundary conditions are first inspected analytically by applying systematically the results of a multiscale analysis to boundary nodes. This procedure makes it possible to compare boundary conditions on an equal footing, although they were originally derived from very different principles. It is concluded that all five boundary conditions exhibit second-order accuracy, consistent with the accuracy of the lattice Boltzmann method. The five methods are then compared numerically for accuracy and stability through benchmarks of two-dimensional and three-dimensional flows. None of the methods is found to be throughout superior to the others. Instead, the choice of a best boundary condition depends on the flow geometry, and on the desired trade-off between accuracy and stability. From the findings of the benchmarks, the boundary conditions can be classified into two major groups. The first group comprehends boundary conditions that preserve the information streaming from the bulk into boundary nodes and complete the missing information through closure relations. Boundary conditions in this group are found to be exceptionally accurate at low Reynolds number. Boundary conditions of the second group replace all variables on boundary nodes by new values. They exhibit generally much better numerical stability and are therefore dedicated for use in high Reynolds number flows.

A Method for Measuring Sludge Settling Characteristics in Turbulent Flows

DEFF Research Database (Denmark)

Rasmussen, Michael R.; Larsen, Torben

1996-01-01

A method for the determination of the settlilng velocity for sludge as a funktion of turbulence intensity and sludge concentration has been developed. The principle of the method is to continuously feed the top of a settling column with sludge so that a steady state and uniform concentration...... distribution occurs in the middle of the column. This eliminates time scale effects such as flocculation from the measurements, as the resulting settling velocity only can be found at steady state and uniform conditions. The method assumes that flocculated sludge settles faster than disintegratedsludge to make...... a mass balance involving concentration at the top and the middle of the column as well as the inlet sludge flow. The resulting mass balance is used to calculate a lokal settling velocity. The turbulence is introduced by an oscillating grid in the whole depth of the settling column. Settling velocities...

Errors analysis in the evaluation of particle concentration by PDA on a turbulent two-phase jet: application for cross section and transit time methods

Science.gov (United States)

Calvo, Esteban; García, Juan A.; García, Ignacio; Aísa, Luis A.

2009-09-01

Phase-Doppler anemometry (PDA) is a powerful tool for two-phase flow measurements and testing. Particle concentration and mass flux can also be evaluated using the raw particle data supplied by this technique. The calculation starts from each particle velocity, diameter, transit time data, and the total measurement time. There are two main evaluation strategies. The first one uses the probe volume effective cross section, and it is usually simplified assuming that particles follow quasi one-directional trajectories. In the text, it will be called the cross section method. The second one includes a set of methods which will be denoted as “Generalized Integral Methods” (GIM). Concentration algorithms such as the transit time method (TTM) and the integral volume method (IVM) are particular cases of the GIM. In any case, a previous calibration of the measurement volume geometry is necessary to apply the referred concentration evaluation methods. In this study, concentrations and mass fluxes both evaluated by the cross-section method and the TTM are compared. Experimental data are obtained from a particle-laden jet generated by a convergent nozzle. Errors due to trajectory dispersion, burst splitting, and multi-particle signals are discussed.

A method of uranium isotopes concentration analysis

International Nuclear Information System (INIS)

Lin Yuangen; Jiang Meng; Wu Changli; Duan Zhanyuan; Guo Chunying

2010-01-01

A basic method of uranium isotopes concentration is described in this paper. The iteration method is used to calculate the relative efficiency curve, by analyzing the characteristic γ energy spectrum of 235 U, 232 U and the daughter nuclide of 238 U, then the relative activity can be calculated, at last the uranium isotopes concentration can be worked out, and the result is validated by the experimentation. (authors)

Rayleigh-wave phase-velocity maps and three-dimensional shear velocity structure of the western US from local non-plane surface wave tomography

Science.gov (United States)

Pollitz, F.F.; Snoke, J. Arthur

2010-01-01

We utilize two-and-three-quarter years of vertical-component recordings made by the Transportable Array (TA) component of Earthscope to constrain three-dimensional (3-D) seismic shear wave velocity structure in the upper 200 km of the western United States. Single-taper spectral estimation is used to compile measurements of complex spectral amplitudes from 44 317 seismograms generated by 123 teleseismic events. In the first step employed to determine the Rayleigh-wave phase-velocity structure, we implement a new tomographic method, which is simpler and more robust than scattering-based methods (e.g. multi-plane surface wave tomography). The TA is effectively implemented as a large number of local arrays by defining a horizontal Gaussian smoothing distance that weights observations near a given target point. The complex spectral-amplitude measurements are interpreted with the spherical Helmholtz equation using local observations about a succession of target points, resulting in Rayleigh-wave phase-velocity maps at periods over the range of 18–125 s. The derived maps depend on the form of local fits to the Helmholtz equation, which generally involve the nonplane-wave solutions of Friederich et al. In a second step, the phase-velocity maps are used to derive 3-D shear velocity structure. The 3-D velocity images confirm details witnessed in prior body-wave and surface-wave studies and reveal new structures, including a deep (>100 km deep) high-velocity lineament, of width ∼200 km, stretching from the southern Great Valley to northern Utah that may be a relic of plate subduction or, alternatively, either a remnant of the Mojave Precambrian Province or a mantle downwelling. Mantle seismic velocity is highly correlated with heat flow, Holocene volcanism, elastic plate thickness and seismicity. This suggests that shallow mantle structure provides the heat source for associated magmatism, as well as thinning of the thermal lithosphere, leading to relatively high

Estimation of vector velocity

DEFF Research Database (Denmark)

2000-01-01

Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

Shallow velocity model in the area of Pozzo Pitarrone, Mt. Etna, from single station, array methods and borehole data

Directory of Open Access Journals (Sweden)

Luciano Zuccarello

2016-09-01

Full Text Available Seismic noise recorded by a temporary array installed around Pozzo Pitarrone, NE flank of Mt. Etna, have been analysed with several techniques. Single station HVSR method and SPAC array method have been applied to stationary seismic noise to investigate the local shallow structure. The inversion of dispersion curves produced a shear wave velocity model of the area reliable down to depth of about 130 m. A comparison of such model with the stratigraphic information available for the investigated area shows a good qualitative agreement. Taking advantage of a borehole station installed at 130 m depth, we could estimate also the P-wave velocity by comparing the borehole recordings of local earthquakes with the same event recorded at surface. Further insight on the P-wave velocity in the upper 130 m layer comes from the surface reflected wave observable in some cases at the borehole station. From this analysis we obtained an average P-wave velocity of about 1.2 km/s, compatible with the shear wave velocity found from the analysis of seismic noise.

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African Journals Online (AJOL)

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The method involves using a water pump, a variable voltage. The method involves using ... followed established trends such that terminal velocity and drop kinetic such that terminal ... produce a distribution of droplets unless a variety of drop forming sized .... attributed to the system's voltage regulation given that the variable ...

Detonation velocity in poorly mixed gas mixtures

Science.gov (United States)

Prokhorov, E. S.

2017-10-01

The technique for computation of the average velocity of plane detonation wave front in poorly mixed mixture of gaseous hydrocarbon fuel and oxygen is proposed. Here it is assumed that along the direction of detonation propagation the chemical composition of the mixture has periodic fluctuations caused, for example, by layered stratification of gas charge. The technique is based on the analysis of functional dependence of ideal (Chapman-Jouget) detonation velocity on mole fraction (with respect to molar concentration) of the fuel. It is shown that the average velocity of detonation can be significantly (by more than 10%) less than the velocity of ideal detonation. The dependence that permits to estimate the degree of mixing of gas mixture basing on the measurements of average detonation velocity is established.

S-wave velocity measurements along levees in New Orleans using passive surface wave methods

Science.gov (United States)

Hayashi, K.; Lorenzo, J. M.; Craig, M. S.; Gostic, A.

2017-12-01

In order to develop non-invasive methods for levee inspection, geophysical investigations were carried out at four sites along levees in the New Orleans area: 17th Street Canal, London Avenue Canal, Marrero Levee, and Industrial Canal. Three of the four sites sustained damage from Hurricane Katrina in 2005 and have since been rebuilt. The geophysical methods used include active and passive surface wave methods, and capacitively coupled resistivity. This paper summarizes the acquisition and analysis of the 1D and 2D passive surface wave data. Twelve wireless seismic data acquisition units with 2 Hz vertical component geophones were used to record data. Each unit includes a GPS receiver so that all units can be synchronized over any distance without cables. The 1D passive method used L shaped arrays of three different sizes with geophone spacing ranging from 5 to 340 m. Ten minutes to one hour of ambient noise was recorded with each array, and total data acquisition took approximately two hours at each site. The 2D method used a linear array with a geophone spacing of 5m. Four geophones were moved forward every 10 minutes along 400 1000 m length lines. Data acquisition took several hours for each line. Recorded ambient noise was processed using the spatial autocorrelation method and clear dispersion curves were obtained at all sites (Figure 1a). Minimum frequencies ranged from 0.4 to 0.7 Hz and maximum frequencies ranged from 10 to 30 Hz depending on the site. Non-linear inversion was performed and 1D and 2D S-wave velocity models were obtained. The 1D method penetrated to depths ranging from 200 to 500 m depending on the site (Figure 1b). The 2D method penetrated to a depth of 40 60 m and provided 400 1000 m cross sections along the levees (Figure 2). The interpretation focused on identifying zones beneath the levees or canal walls having low S-wave velocities corresponding to saturated, unconsolidated sands, or low-rigidity clays. Resultant S-wave velocity profiles

Settling velocities in batch sedimentation

International Nuclear Information System (INIS)

Fricke, A.M.; Thompson, B.E.

1982-10-01

The sedimentation of mixtures containing one and two sizes of spherical particles (44 and 62 μm in diameter) was studied. Radioactive tracing with 57 Co was used to measure the settling velocities. The ratio of the settling velocity U of uniformly sized particles to the velocity predicted to Stokes' law U 0 was correlated to an expression of the form U/U 0 = epsilon/sup α/, where epsilon is the liquid volume fraction and α is an empirical constant, determined experimentally to be 4.85. No effect of viscosity on the ratio U/U 0 was observed as the viscosity of the liquid medium was varied from 1x10 -3 to 5x10 -3 Pa.s. The settling velocities of particles in a bimodal mixture were fit by the same correlation; the ratio U/U 0 was independent of the concentrations of different-sized particles

Review and statistical analysis of the ultrasonic velocity method for estimating the porosity fraction in polycrystalline materials

International Nuclear Information System (INIS)

Roth, D.J.; Swickard, S.M.; Stang, D.B.; Deguire, M.R.

1990-03-01

A review and statistical analysis of the ultrasonic velocity method for estimating the porosity fraction in polycrystalline materials is presented. Initially, a semi-empirical model is developed showing the origin of the linear relationship between ultrasonic velocity and porosity fraction. Then, from a compilation of data produced by many researchers, scatter plots of velocity versus percent porosity data are shown for Al2O3, MgO, porcelain-based ceramics, PZT, SiC, Si3N4, steel, tungsten, UO2,(U0.30Pu0.70)C, and YBa2Cu3O(7-x). Linear regression analysis produced predicted slope, intercept, correlation coefficient, level of significance, and confidence interval statistics for the data. Velocity values predicted from regression analysis for fully-dense materials are in good agreement with those calculated from elastic properties

Determination of velocity correction factors for real-time air velocity monitoring in underground mines.

Science.gov (United States)

Zhou, Lihong; Yuan, Liming; Thomas, Rick; Iannacchione, Anthony

2017-12-01

When there are installations of air velocity sensors in the mining industry for real-time airflow monitoring, a problem exists with how the monitored air velocity at a fixed location corresponds to the average air velocity, which is used to determine the volume flow rate of air in an entry with the cross-sectional area. Correction factors have been practically employed to convert a measured centerline air velocity to the average air velocity. However, studies on the recommended correction factors of the sensor-measured air velocity to the average air velocity at cross sections are still lacking. A comprehensive airflow measurement was made at the Safety Research Coal Mine, Bruceton, PA, using three measuring methods including single-point reading, moving traverse, and fixed-point traverse. The air velocity distribution at each measuring station was analyzed using an air velocity contour map generated with Surfer ® . The correction factors at each measuring station for both the centerline and the sensor location were calculated and are discussed.

A method of solution for the determination of the velocity profiles in turbulent flow through annular tobes

International Nuclear Information System (INIS)

Schmal, M.; Russo, Q.; Almeida, M.S.; Bozzo, S.

1975-01-01

A method of solutions is presented for the determination of the velocity profiles in turbulent flow through annular tubes, based on the Von Karman similarity theory developed by Quarmby. The parameters found by Quarmby appearing in the velocity profiles and determined experimentally by different authors were approximated by polynonial functions of variable degree, as function of the Reynolds numbers. The Runge-Kutta-Nystrom method was used in the integration of the differential equations and the systematic of solution is presented in a computer program. The calculated results were compared to the experimental date and presented a deviation of 10 -2 % [pt

Anaerobic membrane bioreactors and the influence of space velocity and biomass concentration on methane production for liquid dairy manure

International Nuclear Information System (INIS)

Wallace, James M.; Safferman, Steven I.

2014-01-01

Two pilot-scale anaerobic membrane bioreactors (AnMBRs) and a control completely mixed digester (CMD) were constructed to evaluate the influence of space velocity and biomass concentration on methane production for sand separated dairy manure. A negative impact on methane production resulted with operating the AnMBR system at 972 μHz–2960 μHz but no impact was found when operating at 69 μHz and 312 μHz. Operating at 69 μHz–350 μHz is realistic for a field installation. Despite the higher biomass concentration, the methane production of the AnMBRs was nearly equal to the CMD. An AnMBR with 69 μHz was operated equivalent to a CMD by returning all permeate to the digester tank and removing excess biomass directly from the reactor tank resulting in a hydraulic retention time (HRT) equal to the solids retention time (SRT). When using sand separated dairy manure and an HRT (and equal SRT) of 12 d, both systems produced methane at an equal rate, suggesting that the pump/membrane system did not influence methane production. The most likely reason was mass transfer limitations of hydrolytic enzymes. Based on methane production and volatile fatty acids analysis, it appears the fermentable substrate available for degradation was similar. The AnMBR proved to have benefit as part of an integrated nutrient management system that produced water that is virtually free of particulate nutrients, especially phosphorus. This enables the irrigation of the water to crops that need nitrogen and the efficient movement of phosphorus, as a solid, to needed locations. - Highlights: • Manure AnMBRs with a high space velocity inhibit methane production. • Manure AnMBRs with a low space velocity perform similar to conventional digesters. • Decoupled HRT and SRT in manure AnMBRs do not increase methane production. • Ultrafiltration membranes effectively partitioned manure nutrients from the liquid. • Manure does not foul ultrafiltration membranes and require mild

A numerical CFD method for the broiler house ventilation analysis

Czech Academy of Sciences Publication Activity Database

Kic, P.; Zajíček, Milan

2011-01-01

Roč. 4, č. 1 (2011), s. 1-7 ISSN 1546-959X Institutional research plan: CEZ:AV0Z10750506 Institutional support: RVO:67985556 Keywords : poultry * air * velocity * temperature * CFD Subject RIV: GB - Machines ; Buildings for Agriculture http://library.utia.cas.cz/separaty/2013/VS/zajicek-0394097.pdf

A parabolic velocity-decomposition method for wind turbines

Science.gov (United States)

Mittal, Anshul; Briley, W. Roger; Sreenivas, Kidambi; Taylor, Lafayette K.

2017-02-01

An economical parabolized Navier-Stokes approximation for steady incompressible flow is combined with a compatible wind turbine model to simulate wind turbine flows, both upstream of the turbine and in downstream wake regions. The inviscid parabolizing approximation is based on a Helmholtz decomposition of the secondary velocity vector and physical order-of-magnitude estimates, rather than an axial pressure gradient approximation. The wind turbine is modeled by distributed source-term forces incorporating time-averaged aerodynamic forces generated by a blade-element momentum turbine model. A solution algorithm is given whose dependent variables are streamwise velocity, streamwise vorticity, and pressure, with secondary velocity determined by two-dimensional scalar and vector potentials. In addition to laminar and turbulent boundary-layer test cases, solutions for a streamwise vortex-convection test problem are assessed by mesh refinement and comparison with Navier-Stokes solutions using the same grid. Computed results for a single turbine and a three-turbine array are presented using the NREL offshore 5-MW baseline wind turbine. These are also compared with an unsteady Reynolds-averaged Navier-Stokes solution computed with full rotor resolution. On balance, the agreement in turbine wake predictions for these test cases is very encouraging given the substantial differences in physical modeling fidelity and computer resources required.

A compression algorithm for the combination of PDF sets

NARCIS (Netherlands)

Carrazza, Stefano; Latorre, Jose I.; Rojo, Juan; Watt, Graeme

2015-01-01

The current PDF4LHC recommendation to estimate uncertainties due to parton distribution functions (PDFs) in theoretical predictions for LHC processes involves the combination of separate predictions computed using PDF sets from different groups, each of which comprises a relatively large number of

New method of design of nonimaging concentrators.

Science.gov (United States)

Miñano, J C; González, J C

1992-06-01

A new method of designing nonimaging concentrators is presented and two new types of concentrators are developed. The first is an aspheric lens, and the second is a lens-mirror combination. A ray tracing of three-dimensional concentrators (with rotational symmetry) is also done, showing that the lens-mirror combination has a total transmission as high as that of the full compound parabolic concentrators, while their depth is much smaller than the classical parabolic mirror-nonimaging concentrator combinations. Another important feature of this concentrator is that the optically active surfaces are not in contact with the receiver, as occurs in other nonimaging concentrators in which the rim of the mirror coincides with the rim of the receiver.

Prediction of shear wave velocity using empirical correlations and artificial intelligence methods

Science.gov (United States)

Maleki, Shahoo; Moradzadeh, Ali; Riabi, Reza Ghavami; Gholami, Raoof; Sadeghzadeh, Farhad

2014-06-01

Good understanding of mechanical properties of rock formations is essential during the development and production phases of a hydrocarbon reservoir. Conventionally, these properties are estimated from the petrophysical logs with compression and shear sonic data being the main input to the correlations. This is while in many cases the shear sonic data are not acquired during well logging, which may be for cost saving purposes. In this case, shear wave velocity is estimated using available empirical correlations or artificial intelligent methods proposed during the last few decades. In this paper, petrophysical logs corresponding to a well drilled in southern part of Iran were used to estimate the shear wave velocity using empirical correlations as well as two robust artificial intelligence methods knows as Support Vector Regression (SVR) and Back-Propagation Neural Network (BPNN). Although the results obtained by SVR seem to be reliable, the estimated values are not very precise and considering the importance of shear sonic data as the input into different models, this study suggests acquiring shear sonic data during well logging. It is important to note that the benefits of having reliable shear sonic data for estimation of rock formation mechanical properties will compensate the possible additional costs for acquiring a shear log.

Prediction of shear wave velocity using empirical correlations and artificial intelligence methods

Directory of Open Access Journals (Sweden)

Shahoo Maleki

2014-06-01

Full Text Available Good understanding of mechanical properties of rock formations is essential during the development and production phases of a hydrocarbon reservoir. Conventionally, these properties are estimated from the petrophysical logs with compression and shear sonic data being the main input to the correlations. This is while in many cases the shear sonic data are not acquired during well logging, which may be for cost saving purposes. In this case, shear wave velocity is estimated using available empirical correlations or artificial intelligent methods proposed during the last few decades. In this paper, petrophysical logs corresponding to a well drilled in southern part of Iran were used to estimate the shear wave velocity using empirical correlations as well as two robust artificial intelligence methods knows as Support Vector Regression (SVR and Back-Propagation Neural Network (BPNN. Although the results obtained by SVR seem to be reliable, the estimated values are not very precise and considering the importance of shear sonic data as the input into different models, this study suggests acquiring shear sonic data during well logging. It is important to note that the benefits of having reliable shear sonic data for estimation of rock formation mechanical properties will compensate the possible additional costs for acquiring a shear log.

A Centerless Circular Array Method: Extracting Maximal Information on Phase Velocities of Rayleigh Waves From Microtremor Records From a Simple Seismic Array

Science.gov (United States)

Cho, I.; Tada, T.; Shinozaki, Y.

2005-12-01

We have developed a Centerless Circular Array (CCA) method of microtremor exploration, an algorithm that enables to estimate phase velocities of Rayleigh waves by analyzing vertical-component records of microtremors that are obtained with an array of three or five seismic sensors placed around a circumference. Our CCA method shows a remarkably high performance in long-wavelength ranges because, unlike the frequency-wavenumber spectral method, our method does not resolve individual plane-wave components in the process of identifying phase velocities. Theoretical considerations predict that the resolving power of our CCA method in long-wavelength ranges depends upon the SN ratio, or the ratio of power of the propagating components to that of the non-propagating components (incoherent noise) contained in the records from the seismic array. The applicability of our CCA method to small-sized arrays on the order of several meters in radius has already been confirmed in our earlier work (Cho et al., 2004). We have deployed circular seismic arrays of different sizes at test sites in Japan where the underground structure is well documented through geophysical exploration, and have applied our CCA method to microtremor records to estimate phase velocities of Rayleigh waves. The estimates were then checked against "model" phase velocities that are derived from theoretical calculations. For arrays of 5, 25, 300 and 600 meters in radii, the estimated and model phase velocities demonstrated fine agreement within a broad wavelength range extending from a little larger than 3r (r: the array radius) up to at least 40r, 14r, 42r and 9r, respectively. This demonstrates the applicability of our CCA method to arrays on the order of several to several hundreds of meters in radii, and also illustrates, in a typical way, the markedly high performance of our CCA method in long-wavelength ranges. We have also invented a mathematical model that enables to evaluate the SN ratio in a given

A simple measuring technique of surface flow velocity to analyze the behavior of velocity fields in hydraulic engineering applications.

Science.gov (United States)

Tellez, Jackson; Gomez, Manuel; Russo, Beniamino; Redondo, Jose M.

2015-04-01

An important achievement in hydraulic engineering is the proposal and development of new techniques for the measurement of field velocities in hydraulic problems. The technological advances in digital cameras with high resolution and high speed found in the market, and the advances in digital image processing techniques now provides a tremendous potential to measure and study the behavior of the water surface flows. This technique was applied at the Laboratory of Hydraulics at the Technical University of Catalonia - Barcelona Tech to study the 2D velocity fields in the vicinity of a grate inlet. We used a platform to test grate inlets capacity with dimensions of 5.5 m long and 4 m wide allowing a zone of useful study of 5.5m x 3m, where the width is similar of the urban road lane. The platform allows you to modify the longitudinal slopes from 0% to 10% and transversal slope from 0% to 4%. Flow rates can arrive to 200 l/s. In addition a high resolution camera with 1280 x 1024 pixels resolution with maximum speed of 488 frames per second was used. A novel technique using particle image velocimetry to measure surface flow velocities has been developed and validated with the experimental data from the grate inlets capacity. In this case, the proposed methodology can become a useful tools to understand the velocity fields of the flow approaching the inlet where the traditional measuring equipment have serious problems and limitations. References DigiFlow User Guide. (2012), (June). Russo, B., Gómez, M., & Tellez, J. (2013). Methodology to Estimate the Hydraulic Efficiency of Nontested Continuous Transverse Grates. Journal of Irrigation and Drainage Engineering, 139(10), 864-871. doi:10.1061/(ASCE)IR.1943-4774.0000625 Teresa Vila (1), Jackson Tellez (1), Jesus Maria Sanchez (2), Laura Sotillos (1), Margarita Diez (3, 1), and J., & (1), M. R. (2014). Diffusion in fractal wakes and convective thermoelectric flows. Geophysical Research Abstracts - EGU General Assembly 2014

PDF turbulence modeling and DNS

Science.gov (United States)

Hsu, A. T.

1992-01-01

The problem of time discontinuity (or jump condition) in the coalescence/dispersion (C/D) mixing model is addressed in probability density function (pdf). A C/D mixing model continuous in time is introduced. With the continuous mixing model, the process of chemical reaction can be fully coupled with mixing. In the case of homogeneous turbulence decay, the new model predicts a pdf very close to a Gaussian distribution, with finite higher moments also close to that of a Gaussian distribution. Results from the continuous mixing model are compared with both experimental data and numerical results from conventional C/D models. The effect of Coriolis forces on compressible homogeneous turbulence is studied using direct numerical simulation (DNS). The numerical method used in this study is an eight order compact difference scheme. Contrary to the conclusions reached by previous DNS studies on incompressible isotropic turbulence, the present results show that the Coriolis force increases the dissipation rate of turbulent kinetic energy, and that anisotropy develops as the Coriolis force increases. The Taylor-Proudman theory does apply since the derivatives in the direction of the rotation axis vanishes rapidly. A closer analysis reveals that the dissipation rate of the incompressible component of the turbulent kinetic energy indeed decreases with a higher rotation rate, consistent with incompressible flow simulations (Bardina), while the dissipation rate of the compressible part increases; the net gain is positive. Inertial waves are observed in the simulation results.

Regional versus detailed velocity analysis to quantify hydrate and free gas in marine sediments : the south Shetland margin case study

Energy Technology Data Exchange (ETDEWEB)

Tinivella, U.; Loreto, M.F.; Accaino, F. [Inst. Nazionale di Oceanografia di Geofisica Sperimentale, Trieste (Italy)

2008-07-01

The presence of gas hydrate and free gas within marine sediments, deposited along the South Shetland margin, offshore the Antarctic Peninsula, was confirmed by low and high resolution geophysical data, acquired during three research cruises in 1989-1990. Seismic data analysis has demonstrated the presence of a bottom simulating reflector that is very strong and continuous in the eastern part of the margin. This seismic dataset was used in the past to extract detailed velocity information of the shallow structures by using traditional tomographic inversion and jointly tomographic inversion and pre-stack depth migration tool. This paper presented a method to obtain a regional seismic velocity field and information about hydrate and free gas presence in the marine sediments, by using an improved method of the standard analysis of the pre-stack depth migration output. The velocity field was obtained with a layer stripping approach and tomographic inversion of the reflections observed in common image gathering. The paper presented the seismic data and regional and detailed velocity analysis. The results of residual semblance analyses were also presented. Gas phase concentrations were then discussed. The velocity analysis revealed the presence of three main layers characterizing the first kilometer of sediments below the sea floor. In addition, velocity models and related gas-phase sections showed that gas was concentrated in different parts of the profile than where the hydrate was concentrated. This observation confirmed that geological structures and sedimentary processes controlled the gas and hydrate distribution, as observed along other margins. 7 refs., 5 figs.

Experimental validation of alternate integral-formulation method for predicting acoustic radiation based on particle velocity measurements.

Science.gov (United States)

Ni, Zhi; Wu, Sean F

2010-09-01

This paper presents experimental validation of an alternate integral-formulation method (AIM) for predicting acoustic radiation from an arbitrary structure based on the particle velocities specified on a hypothetical surface enclosing the target source. Both the normal and tangential components of the particle velocity on this hypothetical surface are measured and taken as the input to AIM codes to predict the acoustic pressures in both exterior and interior regions. The results obtained are compared with the benchmark values measured by microphones at the same locations. To gain some insight into practical applications of AIM, laser Doppler anemometer (LDA) and double hotwire sensor (DHS) are used as measurement devices to collect the particle velocities in the air. Measurement limitations of using LDA and DHS are discussed.

The Csub(N) method in cylindrical geometry and one-velocity theory

International Nuclear Information System (INIS)

Kavenoky, A.

1975-01-01

The Csub(N) method of solving the transport equation has been developed at Saclay during the last few years: its main advantage is that the computing time is independent of the size of the media considered. This method is based on a lemma proved by Placzek: an integral equation is provided for the angular flux at the boundaries of the media, its kernel is the infinite medium Green's function. The knowledge of the angular flux at the boundaries of the media allows the fluxes to be calculated at any point. The report is devoted to the application to classical problems in one velocity cylindrical geometry: albedo of the inner and outer problems, extrapolation length for the Milne problem, critical radius [fr

Propositions for a PDF model based on fluid particle acceleration

International Nuclear Information System (INIS)

Minier, J.P.; Pozorski, J.

1997-05-01

This paper describes theoretical propositions to model the acceleration of a fluid particle in a turbulent flow. Such a model is useful for the PDF approach to turbulent reactive flows as well as for the Lagrangian modelling of two-phase flows. The model developed here draws from ideas already put forward by Sawford but which are generalized to the case of non-homogeneous flows. The model is built so as to revert continuously to Pope's model, which uses a Langevin equation for particle velocities, when the Reynolds number becomes very high. The derivation is based on the technique of fast variable elimination. This technique allow a careful analysis of the relations between different levels of modelling. It also allows to address certain problems in a more rigorous way. In particular, application of this technique shows that models presently used can in principle simulate bubbly flows including the pressure-gradient and added-mass forces. (author)

PDF Modeling of Turbulent Combustion

National Research Council Canada - National Science Library

Pope, Stephen B

2006-01-01

.... The PDF approach to turbulent combustion has the advantages of fully representing the turbulent fluctuations of species and temperature, and of allowing realistic combustion chemistry to be implemented...

Imaging of 3-D seismic velocity structure of Southern Sumatra region using double difference tomographic method

Energy Technology Data Exchange (ETDEWEB)

Lestari, Titik, E-mail: t2klestari@gmail.com [Meteorological Climatological and Geophysical Agency (MCGA), Jalan Angkasa I No.2 Kemayoran, Jakarta Pusat, 10720 (Indonesia); Faculty of Earth Science and Technology, Bandung Institute of Technology, Jalan Ganesa No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Bandung Institute of Technology, Jalan Ganesa 10 Bandung 40132 (Indonesia)

2015-04-24

Southern Sumatra region has a high level of seismicity due to the influence of the subduction system, Sumatra fault, Mentawai fault and stretching zone activities. The seismic activities of Southern Sumatra region are recorded by Meteorological Climatological and Geophysical Agency (MCGA’s) Seismograph network. In this study, we used earthquake data catalog compiled by MCGA for 3013 events from 10 seismic stations around Southern Sumatra region for time periods of April 2009 – April 2014 in order to invert for the 3-D seismic velocities structure (Vp, Vs, and Vp/Vs ratio). We applied double-difference seismic tomography method (tomoDD) to determine Vp, Vs and Vp/Vs ratio with hypocenter adjustment. For the inversion procedure, we started from the initial 1-D seismic velocity model of AK135 and constant Vp/Vs of 1.73. The synthetic travel time from source to receiver was calculated using ray pseudo-bending technique, while the main tomographic inversion was applied using LSQR method. The resolution model was evaluated using checkerboard test and Derivative Weigh Sum (DWS). Our preliminary results show low Vp and Vs anomalies region along Bukit Barisan which is may be associated with weak zone of Sumatran fault and migration of partial melted material. Low velocity anomalies at 30-50 km depth in the fore arc region may indicated the hydrous material circulation because the slab dehydration. We detected low seismic seismicity in the fore arc region that may be indicated as seismic gap. It is coincides contact zone of high and low velocity anomalies. And two large earthquakes (Jambi and Mentawai) also occurred at the contact of contrast velocity.

Validity of a Simple Method for Measuring Force-Velocity-Power Profile in Countermovement Jump.

Science.gov (United States)

Jiménez-Reyes, Pedro; Samozino, Pierre; Pareja-Blanco, Fernando; Conceição, Filipe; Cuadrado-Peñafiel, Víctor; González-Badillo, Juan José; Morin, Jean-Benoît

2017-01-01

To analyze the reliability and validity of a simple computation method to evaluate force (F), velocity (v), and power (P) output during a countermovement jump (CMJ) suitable for use in field conditions and to verify the validity of this computation method to compute the CMJ force-velocity (F-v) profile (including unloaded and loaded jumps) in trained athletes. Sixteen high-level male sprinters and jumpers performed maximal CMJs under 6 different load conditions (0-87 kg). A force plate sampling at 1000 Hz was used to record vertical ground-reaction force and derive vertical-displacement data during CMJ trials. For each condition, mean F, v, and P of the push-off phase were determined from both force-plate data (reference method) and simple computation measures based on body mass, jump height (from flight time), and push-off distance and used to establish the linear F-v relationship for each individual. Mean absolute bias values were 0.9% (± 1.6%), 4.7% (± 6.2%), 3.7% (± 4.8%), and 5% (± 6.8%) for F, v, P, and slope of the F-v relationship (S Fv ), respectively. Both methods showed high correlations for F-v-profile-related variables (r = .985-.991). Finally, all variables computed from the simple method showed high reliability, with ICC >.980 and CV push-off distance, and jump height are known.

Vector blood velocity estimation in medical ultrasound

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt; Gran, Fredrik; Udesen, Jesper

2006-01-01

Two methods for making vector velocity estimation in medical ultrasound are presented. All of the techniques can find both the axial and transverse velocity in the image and can be used for displaying both the correct velocity magnitude and direction. The first method uses a transverse oscillation...... in the ultrasound field to find the transverse velocity. In-vivo examples from the carotid artery are shown, where complex turbulent flow is found in certain parts of the cardiac cycle. The second approach uses directional beam forming along the flow direction to estimate the velocity magnitude. Using a correlation...... search can also yield the direction, and the full velocity vector is thereby found. An examples from a flow rig is shown....

A study on the high velocity impact behavior of titanium alloy by PVD method

International Nuclear Information System (INIS)

Sohn, Se Won; Lee, Doo Sung; Hong, Sung Hee

2001-01-01

In order to investigate the fracture behaviors(penetration modes) and resistance to penetration during ballistic impact of titanium alloy laminates and nitrified titanium alloy laminates which were treated by PVD(Physical Vapor Deposition) method, ballistic tests were conducted. Evaporation, sputtering, and ion plating are three kinds of PVD method. In this research, ion plating was used to achieve higher surface hardness and surface hardness test were conducted using a micro Vicker's hardness tester. Resistance to penetration is determined by the protection ballistic limit(V 50 ), a statistical velocity with 50% probability for complete penetration. Fracture behaviors and ballistic tolerance, described by penetration modes, are respectfully observed at and above ballistic limit velocities, as a result of V 50 test and Projectile Through Plates(PTP) test methods. PTP tests were conducted with 0 .deg. obliquity at room temperature using 5.56mm ball projectile. V 50 tests with 0 .deg. obliquity at room temperature were conducted with projectiles that were able to achieve near or complete penetration during PTP tests. Surface hardness, resistance to penetration, and penetration modes of titanium alloy laminates are compared to those of nitrified titanium alloy laminates

Allowable CO2 concentrations under the United Nations Framework Convention on Climate Change as a function of the climate sensitivity probability distribution function

International Nuclear Information System (INIS)

Harvey, L D Danny

2007-01-01

Article 2 of the United Nations Framework Convention on Climate Change (UNFCCC) calls for stabilization of greenhouse gas (GHG) concentrations at levels that prevent dangerous anthropogenic interference (DAI) in the climate system. Until recently, the consensus viewpoint was that the climate sensitivity (the global mean equilibrium warming for a doubling of atmospheric CO 2 concentration) was 'likely' to fall between 1.5 and 4.5 K. However, a number of recent studies have generated probability distribution functions (pdfs) for climate sensitivity with the 95th percentile of the expected climate sensitivity as large as 10 K, while some studies suggest that the climate sensitivity is likely to fall in the lower half of the long-standing 1.5-4.5 K range. This paper examines the allowable CO 2 concentration as a function of the 95th percentile of the climate sensitivity pdf (ranging from 2 to 8 K) and for the following additional assumptions: (i) the 50th percentile for the pdf of the minimum sustained global mean warming that causes unacceptable harm equal to 1.5 or 2.5 K; and (ii) 1%, 5% or 10% allowable risks of unacceptable harm. For a 1% risk tolerance and the more stringent harm-threshold pdf, the allowable CO 2 concentration ranges from 323 to 268 ppmv as the 95th percentile of the climate sensitivity pdf increases from 2 to 8 K, while for a 10% risk tolerance and the less stringent harm-threshold pdf, the allowable CO 2 concentration ranges from 531 to 305 ppmv. In both cases it is assumed that non-CO 2 GHG radiative forcing can be reduced to half of its present value, otherwise; the allowable CO 2 concentration is even smaller. Accounting for the fact that the CO 2 concentration will gradually fall if emissions are reduced to zero, and that peak realized warming will then be less than the peak equilibrium warming (related to peak radiative forcing) allows the CO 2 concentration to peak at 10-40 ppmv higher than the limiting values given above for a climate

Application research of computational mass-transfer differential equation in MBR concentration field simulation.

Science.gov (United States)

Li, Chunqing; Tie, Xiaobo; Liang, Kai; Ji, Chanjuan

2016-01-01

After conducting the intensive research on the distribution of fluid's velocity and biochemical reactions in the membrane bioreactor (MBR), this paper introduces the use of the mass-transfer differential equation to simulate the distribution of the chemical oxygen demand (COD) concentration in MBR membrane pool. The solutions are as follows: first, use computational fluid dynamics to establish a flow control equation model of the fluid in MBR membrane pool; second, calculate this model by adopting direct numerical simulation to get the velocity field of the fluid in membrane pool; third, combine the data of velocity field to establish mass-transfer differential equation model for the concentration field in MBR membrane pool, and use Seidel iteration method to solve the equation model; last but not least, substitute the real factory data into the velocity and concentration field model to calculate simulation results, and use visualization software Tecplot to display the results. Finally by analyzing the nephogram of COD concentration distribution, it can be found that the simulation result conforms the distribution rule of the COD's concentration in real membrane pool, and the mass-transfer phenomenon can be affected by the velocity field of the fluid in membrane pool. The simulation results of this paper have certain reference value for the design optimization of the real MBR system.

An asymptotic inversion method of inferring the sound velocity distribution in the sun from the spectrum of p-mode oscillations

International Nuclear Information System (INIS)

Sekii, Takashi; Shibahashi, Hiromoto

1989-01-01

We present an inversion method of inferring the sound velocity distribution in the Sun from its oscillation data of p-modes. The equation governing the p-mode oscillations is reduced to a form similar to the Schroedinger equation in quantum mechanics. By using a quantization rule based on the KWBJ asymptotic method, we derive an integral equation of which solution provides the 'acoustic potential' of the wave equation. The acoustic potential consists of two parts: One of them is related with the squared sound velocity and is dependent on the degree of the mode l, while the other term is independent of l and dominates in the outer part of the Sun. By examining the l-dependence of the acoustic potential obtained as the solution of the integral equation, we separate these two components of the potential and eventually obtain the sound velocity distribution from a set of eigenfrequencies of p-modes. In order to evaluate prospects of this inversion method, we perform numerical simulations in which eigenfrequencies of a theoretical solar model are used to reproduce the sound velocity distribution of the model. The error of thus inferred sound velocity relative to the true values is estimated to be less than a few percent. (author)

Performance of a vector velocity estimator

DEFF Research Database (Denmark)

Munk, Peter; Jensen, Jørgen Arendt

1998-01-01

tracking can be found in the literature, but no method with a satisfactory performance has been found that can be used in a commercial implementation. A method for estimation of the velocity vector is presented. Here an oscillation transverse to the ultrasound beam is generated, so that a transverse motion...... in an autocorrelation approach that yields both the axial and the lateral velocity, and thus the velocity vector. The method has the advantage that a standard array transducer and a modified digital beamformer, like those used in modern ultrasound scanners, is sufficient to obtain the information needed. The signal...

Weak second-order splitting schemes for Lagrangian Monte Carlo particle methods for the composition PDF/FDF transport equations

International Nuclear Information System (INIS)

Wang Haifeng; Popov, Pavel P.; Pope, Stephen B.

2010-01-01

We study a class of methods for the numerical solution of the system of stochastic differential equations (SDEs) that arises in the modeling of turbulent combustion, specifically in the Monte Carlo particle method for the solution of the model equations for the composition probability density function (PDF) and the filtered density function (FDF). This system consists of an SDE for particle position and a random differential equation for particle composition. The numerical methods considered advance the solution in time with (weak) second-order accuracy with respect to the time step size. The four primary contributions of the paper are: (i) establishing that the coefficients in the particle equations can be frozen at the mid-time (while preserving second-order accuracy), (ii) examining the performance of three existing schemes for integrating the SDEs, (iii) developing and evaluating different splitting schemes (which treat particle motion, reaction and mixing on different sub-steps), and (iv) developing the method of manufactured solutions (MMS) to assess the convergence of Monte Carlo particle methods. Tests using MMS confirm the second-order accuracy of the schemes. In general, the use of frozen coefficients reduces the numerical errors. Otherwise no significant differences are observed in the performance of the different SDE schemes and splitting schemes.

Supplement to procedures, analysis, and comparison of groundwater velocity measurement methods for unconfined aquifers

International Nuclear Information System (INIS)

Zinkl, R.J.; Kearl, P.M.

1988-09-01

This report is a supplement to Procedures, Analysis, and Comparison of Groundwater Velocity Measurement Methods for Unconfined Aquifers and provides computer program descriptions, type curves, and calculations for the analysis of field data in determining groundwater velocity in unconfined aquifers. The computer programs analyze bail or slug tests, pumping tests, Geoflo Meter data, and borehole dilution data. Appendix A is a description of the code, instructions for using the code, an example data file, and the calculated results to allow checking the code after installation on the user's computer. Calculations, development of formulas, and correction factors for the various programs are presented in Appendices B through F. Appendix G provides a procedure for calculating transmissivity and specific yield for pumping tests performed in unconfined aquifers

Risk methodology for geologic disposal of radioactive waste: The distributed velocity method of solving the convective-dispersion equation

Energy Technology Data Exchange (ETDEWEB)

Campbell, James E; Longsine, Dennis E [Sandia National Laboratories, Albuquerque, New Mexico (United States); Reeves, Mark [INTERA Environmental Consultants, Inc. Houston, TX (United States)

1980-06-01

A new method is proposed for treating convective-dispersive transport. The motivation for developing this technique arises from the demands of performing a risk assessment for a nuclear waste repository. These demands include computational efficiency over a relatively large range of Peclet numbers and the ability to handle chains of decaying radionuclides with rather extreme contrasts in both solution velocities and half lives. To the extent it has been tested to date, the Distributed Velocity Method (DVM) appears to satisfy these demands. Included in this paper are the mathematical theory, numerical implementation, an error analysis employing statistical sampling and regression analysis techniques, and comparisons of DVM with other methods for convective-dispersive transport. (author)

Changes in Ultrasonic Velocity from Fluid Substitution, Calculated with Laboratory Methods, Digital Rock Physics, and Biot Theory

Science.gov (United States)

Goldfarb, E. J.; Ikeda, K.; Tisato, N.

2017-12-01

Seismic and ultrasonic velocities of rocks are function of several variables including fluid saturation and type. Understanding the effect of each variable on elastic waves can be valuable when using seismic methods for subsurface modeling. Fluid type and saturation are of specific interest to volcanology, water, and hydrocarbon exploration. Laboratory testing is often employed to understand the effects of fluids on elastic waves. However, laboratory testing is expensive and time consuming. It normally requires cutting rare samples into regular shapes. Fluid injection can also destroy specimens as removing the fluid after testing can prove difficult. Another option is theoretical modeling, which can be used to predict the effect of fluids on elastic properties, but it is often inaccurate. Alternatively, digital rock physics (DRP) can be used to investigate the effect of fluid substitution. DRP has the benefit of being non invasive, as it does not require regular sample shapes or fluid injection. Here, we compare the three methods for dry and saturated Berea sandstone to test the reliability of DRP. First, ultrasonic velocities were obtained from laboratory testing. Second, for comparison, we used a purely theoretical approach - i.e., Hashin-Shtrikman and Biot theory - to estimate the wave speeds at dry and wet conditions. Third, we used DRP. The dry sample was scanned with micro Computed Tomography (µCT), and a three dimensional (3D) array was recorded. We employed a segmentation-less method to convert each 3D array value to density, porosity, elastic moduli, and wave speeds. Wave propagation was simulated numerically at similar frequency as the laboratory. To simulate fluid substitution, we numerically substituted air values for water and repeated the simulation. The results from DRP yielded similar velocities to the laboratory, and accurately predicted the velocity change from fluid substitution. Theoretical modeling could not accurately predict velocity, and

Travel Times, Streamflow Velocities, and Dispersion Rates in the Yellowstone River, Montana

Science.gov (United States)

McCarthy, Peter M.

2009-01-01

The Yellowstone River is a vital natural resource to the residents of southeastern Montana and is a primary source of water for irrigation and recreation and the primary source of municipal water for several cities. The Yellowstone River valley is the primary east-west transportation corridor through southern Montana. This complex of infrastructure makes the Yellowstone River especially vulnerable to accidental spills from various sources such as tanker cars and trucks. In 2008, the U.S. Geological Survey (USGS), in cooperation with the Montana Department of Environmental Quality, initiated a dye-tracer study to determine instream travel times, streamflow velocities, and dispersion rates for the Yellowstone River from Lockwood to Glendive, Montana. The purpose of this report is to describe the results of this study and summarize data collected at each of the measurement sites between Lockwood and Glendive. This report also compares the results of this study to estimated travel times from a transport model developed by the USGS for a previous study. For this study, Rhodamine WT dye was injected at four locations in late September and early October 2008 during reasonably steady streamflow conditions. Streamflows ranged from 3,490 to 3,770 cubic feet per second upstream from the confluence of the Bighorn River and ranged from 6,520 to 7,570 cubic feet per second downstream from the confluence of the Bighorn River. Mean velocities were calculated for each subreach between measurement sites for the leading edge, peak concentration, centroid, and trailing edge at 10 percent of the peak concentration. Calculated velocities for the centroid of the dye plume for subreaches that were completely laterally mixed ranged from 1.83 to 3.18 ft/s within the study reach from Lockwood Bridge to Glendive Bridge. The mean of the completely mixed centroid velocity for the entire study reach, excluding the subreach between Forsyth Bridge and Cartersville Dam, was 2.80 ft/s. Longitudinal

A Simple Method for Determination of Critical Swimming Velocity in Swimming Flume

OpenAIRE

高橋, 繁浩; 若吉, 浩二; Shigehiro, TAKAHASHI; Kohji, WAKAYOSHI; 中京大学; 奈良教育大学教育学部

2001-01-01

The purpose of this study was to investigate a simple method for determination of critical swimming velocity (Vcri). Vcri is defined by Wakayoshi et al. (1992) as the swimming speed which could theoretically be maintained forever without exhaustion, and is expressed as the slope of a regression line between swimming distance (D) and swimming time (T) obtained at various swimming speeds. To determine Vcri, 20 well-trained swimmers were measured at several swimming speeds ranging from 1.25 m/se...

Uncertainty assessment of 3D instantaneous velocity model from stack velocities

Science.gov (United States)

Emanuele Maesano, Francesco; D'Ambrogi, Chiara

2015-04-01

3D modelling is a powerful tool that is experiencing increasing applications in data analysis and dissemination. At the same time the need of quantitative uncertainty evaluation is strongly requested in many aspects of the geological sciences and by the stakeholders. In many cases the starting point for 3D model building is the interpretation of seismic profiles that provide indirect information about the geology of the subsurface in the domain of time. The most problematic step in the 3D modelling construction is the conversion of the horizons and faults interpreted in time domain to the depth domain. In this step the dominant variable that could lead to significantly different results is the velocity. The knowledge of the subsurface velocities is related mainly to punctual data (sonic logs) that are often sparsely distributed in the areas covered by the seismic interpretation. The extrapolation of velocity information to wide extended horizons is thus a critical step to obtain a 3D model in depth that can be used for predictive purpose. In the EU-funded GeoMol Project, the availability of a dense network of seismic lines (confidentially provided by ENI S.p.A.) in the Central Po Plain, is paired with the presence of 136 well logs, but few of them have sonic logs and in some portion of the area the wells are very widely spaced. The depth conversion of the 3D model in time domain has been performed testing different strategies for the use and the interpolation of velocity data. The final model has been obtained using a 4 layer cake 3D instantaneous velocity model that considers both the initial velocity (v0) in every reference horizon and the gradient of velocity variation with depth (k). Using this method it is possible to consider the geological constraint given by the geometries of the horizons and the geo-statistical approach to the interpolation of velocities and gradient. Here we present an experiment based on the use of set of pseudo-wells obtained from the

Examples of in-vivo blood vector velocity estimation

DEFF Research Database (Denmark)

Udesen, Jesper; Nielsen, Michael Bachmann; Nielsen, Kristian R.

2007-01-01

In this paper examples of in-vivo blood vector velocity images of the carotid artery are presented. The transverse oscillation (TO) method for blood vector velocity estimation has been used to estimate the vector velocities and the method is first evaluated in a circulating flowrig where...

Three dimensional reflection velocity analysis based on velocity model scan; Model scan ni yoru sanjigen hanshaha sokudo kaiseki

Energy Technology Data Exchange (ETDEWEB)

Minegishi, M; Tsuru, T [Japan National Oil Corp., Tokyo (Japan); Matsuoka, T [Japan Petroleum Exploration Corp., Tokyo (Japan)

1996-05-01

Introduced herein is a reflection wave velocity analysis method using model scanning as a method for velocity estimation across a section, the estimation being useful in the construction of a velocity structure model in seismic exploration. In this method, a stripping type analysis is carried out, wherein optimum structure parameters are determined for reflection waves one after the other beginning with those from shallower parts. During this process, the velocity structures previously determined for the shallower parts are fixed and only the lowest of the layers undergoing analysis at the time is subjected to model scanning. To consider the bending of ray paths at each velocity boundaries involving shallower parts, the ray path tracing method is utilized for the calculation of the reflection travel time curve for the reflection surface being analyzed. Out of the reflection wave travel time curves calculated using various velocity structure models, one that suits best the actual reflection travel time is detected. The degree of matching between the calculated result and actual result is measured by use of data semblance in a time window provided centering about the calculated reflective wave travel time. The structure parameter is estimated on the basis of conditions for the maximum semblance. 1 ref., 4 figs.

The Use of PDF/A in Digital Archives: A Case Study from Archaeology

Directory of Open Access Journals (Sweden)

Tim N. L. Evans

2014-10-01

Full Text Available In recent years the Portable Document Format (PDF has become a ubiquitous format in the exchange of documents; in 2005 the PDF/A profile was defined in order to meet long term accessibility needs, and has accordingly come to be regarded as a long-term archiving strategy for PDF files. In the field of archaeology, a growing number of PDF files – containing the detailed results of fieldwork and research – are beginning to be deposited with digital archives such as the Archaeology Data Service (ADS. In the ADS’ experience, the use of PDF/A has had benefits as well as drawbacks: the majority of PDF reports are now in a standard format better suited to longer-term access, however migrating to PDF/A and managing and ensuring reuse of these files is intensive, and fraught with potential pitfalls. Of these, perhaps the most serious has been an unreliability in PDF/A conformance by the wide range of tools and software now available. There are also practical and more theoretical implications for reuse which, as our discipline of archaeology alongside so many others rapidly becomes digitized, presents us with a large corpus of ‘data’ that is human readable, but may not be amenable to machine-based technologies such as NLP. It may be argued that these factors effectively undermine some of the perceived cost benefit of moving from paper to digital, as well as the longer-term sustainability of PDF/A within digital archives.

Multivariate regression methods for estimating velocity of ictal discharges from human microelectrode recordings

Science.gov (United States)

Liou, Jyun-you; Smith, Elliot H.; Bateman, Lisa M.; McKhann, Guy M., II; Goodman, Robert R.; Greger, Bradley; Davis, Tyler S.; Kellis, Spencer S.; House, Paul A.; Schevon, Catherine A.

2017-08-01

Objective. Epileptiform discharges, an electrophysiological hallmark of seizures, can propagate across cortical tissue in a manner similar to traveling waves. Recent work has focused attention on the origination and propagation patterns of these discharges, yielding important clues to their source location and mechanism of travel. However, systematic studies of methods for measuring propagation are lacking. Approach. We analyzed epileptiform discharges in microelectrode array recordings of human seizures. The array records multiunit activity and local field potentials at 400 micron spatial resolution, from a small cortical site free of obstructions. We evaluated several computationally efficient statistical methods for calculating traveling wave velocity, benchmarking them to analyses of associated neuronal burst firing. Main results. Over 90% of discharges met statistical criteria for propagation across the sampled cortical territory. Detection rate, direction and speed estimates derived from a multiunit estimator were compared to four field potential-based estimators: negative peak, maximum descent, high gamma power, and cross-correlation. Interestingly, the methods that were computationally simplest and most efficient (negative peak and maximal descent) offer non-inferior results in predicting neuronal traveling wave velocities compared to the other two, more complex methods. Moreover, the negative peak and maximal descent methods proved to be more robust against reduced spatial sampling challenges. Using least absolute deviation in place of least squares error minimized the impact of outliers, and reduced the discrepancies between local field potential-based and multiunit estimators. Significance. Our findings suggest that ictal epileptiform discharges typically take the form of exceptionally strong, rapidly traveling waves, with propagation detectable across millimeter distances. The sequential activation of neurons in space can be inferred from clinically

Photodissociation of Small Molecules and Photoionization of Free Radicals Using the VUV Velocity-Map Imaging Photoion and Photoelectron Method

Science.gov (United States)

Gao, Hong

The tunable vacuum ultraviolet (VUV) laser generated through the two-photon resonance-enhanced four-wave mixing scheme is combined with the newly developed time-slice velocity map imaging photoion method to study the photodissociation of small molecules in the VUV region, and with the velocity map imaging photoelectron method to study the photoionization of free radicals. The photodissociation dynamics of NO in the energy region around 13.5 eV has been investigated. Branching ratios of the three lowest dissociation channels of 12C 16O that produce C(3P) + O(3P), C( 1D) + O(3P) and C(3P) + O(1D) are measured for the first time in the VUV region from 102,500 cm-1 to 110,500 cm-1, valuable information of the dissociation dynamics for this prototype system has been deduced. We demonstrated an experiment that has two independently tunable VUV lasers and a time-slice velocity map imaging setup, this provides us a global way to perform systematic state-selected photodissociation of small molecules via state-selected detection of the atomic products in the VUV region. The velocity map imaging photoelectron method was successfully used to obtain the photoelectron spectrum of the propargyl radical (C3H3) via a single VUV photoionization process. The propargyl radical is generated by the 193 nm laser photodissociation of the precursor C3H3Cl. This is the first time that the velocity map imaging photoelectron method is used to get the photoelectron spectra of free radicals, indicating that it is a powerful technique for studying the photoionization of free radicals which are always hard to be produced with high enough number densities for spectroscopic studies. This dissertation is mainly based on the following peer-reviewed journal articles: 1. Hong Gao, Yang Pan, Lei Yang, Jingang Zhou, C. Y. Ng and William M. Jackson. "Time-slice velocity-map ion imaging studies of the Photodissociation of NO in the vacuum ultraviolet region", the Journal of Chemical Physics, 136, 134302

A Two-Radius Circular Array Method: Extracting Independent Information on Phase Velocities of Love Waves From Microtremor Records From a Simple Seismic Array

Science.gov (United States)

Tada, T.; Cho, I.; Shinozaki, Y.

2005-12-01

We have invented a Two-Radius (TR) circular array method of microtremor exploration, an algorithm that enables to estimate phase velocities of Love waves by analyzing horizontal-component records of microtremors that are obtained with an array of seismic sensors placed around circumferences of two different radii. The data recording may be done either simultaneously around the two circles or in two separate sessions with sensors distributed around each circle. Both Rayleigh and Love waves are present in the horizontal components of microtremors, but in the data processing of our TR method, all information on the Rayleigh waves ends up cancelled out, and information on the Love waves alone are left to be analyzed. Also, unlike the popularly used frequency-wavenumber spectral (F-K) method, our TR method does not resolve individual plane-wave components arriving from different directions and analyze their "vector" phase velocities, but instead directly evaluates their "scalar" phase velocities --- phase velocities that contain no information on the arrival direction of waves --- through a mathematical procedure which involves azimuthal averaging. The latter feature leads us to expect that, with our TR method, it is possible to conduct phase velocity analysis with smaller numbers of sensors, with higher stability, and up to longer-wavelength ranges than with the F-K method. With a view to investigating the capabilities and limitations of our TR method in practical implementation to real data, we have deployed circular seismic arrays of different sizes at a test site in Japan where the underground structure is well documented through geophysical exploration. Ten seismic sensors were placed equidistantly around two circumferences, five around each circle, with varying combinations of radii ranging from several meters to several tens of meters, and simultaneous records of microtremors around circles of two different radii were analyzed with our TR method to produce

Decompositions of bubbly flow PIV velocity fields using discrete wavelets multi-resolution and multi-section image method

International Nuclear Information System (INIS)

Choi, Je-Eun; Takei, Masahiro; Doh, Deog-Hee; Jo, Hyo-Jae; Hassan, Yassin A.; Ortiz-Villafuerte, Javier

2008-01-01

Currently, wavelet transforms are widely used for the analyses of particle image velocimetry (PIV) velocity vector fields. This is because the wavelet provides not only spatial information of the velocity vectors, but also of the time and frequency domains. In this study, a discrete wavelet transform is applied to real PIV images of bubbly flows. The vector fields obtained by a self-made cross-correlation PIV algorithm were used for the discrete wavelet transform. The performances of the discrete wavelet transforms were investigated by changing the level of power of discretization. The images decomposed by wavelet multi-resolution showed conspicuous characteristics of the bubbly flows for the different levels. A high spatial bubble concentrated area could be evaluated by the constructed discrete wavelet transform algorithm, in which high-leveled wavelets play dominant roles in revealing the flow characteristics

Blind test of methods for obtaining 2-D near-surface seismic velocity models from first-arrival traveltimes

Science.gov (United States)

Zelt, Colin A.; Haines, Seth; Powers, Michael H.; Sheehan, Jacob; Rohdewald, Siegfried; Link, Curtis; Hayashi, Koichi; Zhao, Don; Zhou, Hua-wei; Burton, Bethany L.; Petersen, Uni K.; Bonal, Nedra D.; Doll, William E.

2013-01-01

Seismic refraction methods are used in environmental and engineering studies to image the shallow subsurface. We present a blind test of inversion and tomographic refraction analysis methods using a synthetic first-arrival-time dataset that was made available to the community in 2010. The data are realistic in terms of the near-surface velocity model, shot-receiver geometry and the data's frequency and added noise. Fourteen estimated models were determined by ten participants using eight different inversion algorithms, with the true model unknown to the participants until it was revealed at a session at the 2011 SAGEEP meeting. The estimated models are generally consistent in terms of their large-scale features, demonstrating the robustness of refraction data inversion in general, and the eight inversion algorithms in particular. When compared to the true model, all of the estimated models contain a smooth expression of its two main features: a large offset in the bedrock and the top of a steeply dipping low-velocity fault zone. The estimated models do not contain a subtle low-velocity zone and other fine-scale features, in accord with conventional wisdom. Together, the results support confidence in the reliability and robustness of modern refraction inversion and tomographic methods.

Field estimates of floc dynamics and settling velocities in a tidal creek with significant along-channel gradients in velocity and SPM

Science.gov (United States)

Schwarz, C.; Cox, T.; van Engeland, T.; van Oevelen, D.; van Belzen, J.; van de Koppel, J.; Soetaert, K.; Bouma, T. J.; Meire, P.; Temmerman, S.

2017-10-01

A short-term intensive measurement campaign focused on flow, turbulence, suspended particle concentration, floc dynamics and settling velocities were carried out in a brackish intertidal creek draining into the main channel of the Scheldt estuary. We compare in situ estimates of settling velocities between a laser diffraction (LISST) and an acoustic Doppler technique (ADV) at 20 and 40 cm above bottom (cmab). The temporal variation in settling velocity estimated were compared over one tidal cycle, with a maximum flood velocity of 0.46 m s-1, a maximum horizontal ebb velocity of 0.35 m s-1 and a maximum water depth at high water slack of 2.41 m. Results suggest that flocculation processes play an important role in controlling sediment transport processes in the measured intertidal creek. During high-water slack, particles flocculated to sizes up to 190 μm, whereas at maximum flood and maximum ebb tidal stage floc sizes only reached up to 55 μm and 71 μm respectively. These large differences indicate that flocculation processes are mainly governed by turbulence-induced shear rate. In this study, we specifically recognize the importance of along-channel gradients that places constraints on the application of the acoustic Doppler technique due to conflicts with the underlying assumptions. Along-channel gradients were assessed by additional measurements at a second location and scaling arguments which could be used as an indication whether the Reynolds-flux method is applicable. We further show the potential impact of along-channel advection of flocs out of equilibrium with local hydrodynamics influencing overall floc sizes.

Rationalizing method of replacement intervals by using Bayesian statistics

International Nuclear Information System (INIS)

Kasai, Masao; Notoya, Junichi; Kusakari, Yoshiyuki

2007-01-01

This study represents the formulations for rationalizing the replacement intervals of equipments and/or parts taking into account the probability density functions (PDF) of the parameters of failure distribution functions (FDF) and compares the optimized intervals by our formulations with those by conventional formulations which uses only representative values of the parameters of FDF instead of using these PDFs. The failure data are generated by Monte Carlo simulations since the real failure data can not be available for us. The PDF of PDF parameters are obtained by Bayesian method and the representative values are obtained by likelihood estimation and Bayesian method. We found that the method using PDF by Bayesian method brings longer replacement intervals than one using the representative of the parameters. (author)

Numerical Loading of a Maxwellian Probability Distribution Function

International Nuclear Information System (INIS)

Lewandowski, J.L.V.

2003-01-01

A renormalization procedure for the numerical loading of a Maxwellian probability distribution function (PDF) is formulated. The procedure, which involves the solution of three coupled nonlinear equations, yields a numerically loaded PDF with improved properties for higher velocity moments. This method is particularly useful for low-noise particle-in-cell simulations with electron dynamics

Three-dimensional modelling of the human carotid artery using the lattice Boltzmann method: I. Model and velocity analysis

Energy Technology Data Exchange (ETDEWEB)

Boyd, J [Cardiovascular Research Group Physics, University of New England, Armidale, NSW 2351 (Australia); Buick, J M [Department of Mechanical and Design Engineering, University of Portsmouth, Anglesea Building, Anglesea Road, Portsmouth PO1 3DJ (United Kingdom)

2008-10-21

Numerical modelling is a powerful tool in the investigation of human blood flow and arterial diseases such as atherosclerosis. It is known that near wall velocity and shear are important in the pathogenesis and progression of atherosclerosis. In this paper results for a simulation of blood flow in a three-dimensional carotid artery geometry using the lattice Boltzmann method are presented. The velocity fields in the body of the fluid are analysed at six times of interest during a physiologically accurate velocity waveform. It is found that the three-dimensional model agrees well with previous literature results for carotid artery flow. Regions of low near wall velocity and circulatory flow are observed near the outer wall of the bifurcation and in the lower regions of the external carotid artery, which are regions that are typically prone to atherosclerosis.

Three-dimensional modelling of the human carotid artery using the lattice Boltzmann method: I. Model and velocity analysis

International Nuclear Information System (INIS)

Boyd, J; Buick, J M

2008-01-01

Numerical modelling is a powerful tool in the investigation of human blood flow and arterial diseases such as atherosclerosis. It is known that near wall velocity and shear are important in the pathogenesis and progression of atherosclerosis. In this paper results for a simulation of blood flow in a three-dimensional carotid artery geometry using the lattice Boltzmann method are presented. The velocity fields in the body of the fluid are analysed at six times of interest during a physiologically accurate velocity waveform. It is found that the three-dimensional model agrees well with previous literature results for carotid artery flow. Regions of low near wall velocity and circulatory flow are observed near the outer wall of the bifurcation and in the lower regions of the external carotid artery, which are regions that are typically prone to atherosclerosis.

Low-density lipoprotein concentration in the normal left coronary artery tree

Directory of Open Access Journals (Sweden)

Louridas George E

2008-10-01

Full Text Available Abstract Background The blood flow and transportation of molecules in the cardiovascular system plays a crucial role in the genesis and progression of atherosclerosis. This computational study elucidates the Low Density Lipoprotein (LDL site concentration in the entire normal human 3D tree of the LCA. Methods A 3D geometry model of the normal human LCA tree is constructed. Angiographic data used for geometry construction correspond to end-diastole. The resulted model includes the LMCA, LAD, LCxA and their main branches. The numerical simulation couples the flow equations with the transport equation applying realistic boundary conditions at the wall. Results High concentration of LDL values appears at bifurcation opposite to the flow dividers in the proximal regions of the Left Coronary Artery (LCA tree, where atherosclerosis frequently occurs. The area-averaged normalized luminal surface LDL concentrations over the entire LCA tree are, 1.0348, 1.054 and 1.23, for the low, median and high water infiltration velocities, respectively. For the high, median and low molecular diffusivities, the peak values of the normalized LDL luminal surface concentration at the LMCA bifurcation reach 1.065, 1.080 and 1.205, respectively. LCA tree walls are exposed to a cholesterolemic environment although the applied mass and flow conditions refer to normal human geometry and normal mass-flow conditions. Conclusion The relationship between WSS and luminal surface concentration of LDL indicates that LDL is elevated at locations where WSS is low. Concave sides of the LCA tree exhibit higher concentration of LDL than the convex sides. Decreased molecular diffusivity increases the LDL concentration. Increased water infiltration velocity increases the LDL concentration. The regional area of high luminal surface concentration is increased with increasing water infiltration velocity. Regions of high LDL luminal surface concentration do not necessarily co-locate to the

The Superstatistical Nature and Interoccurrence Time of Atmospheric Mercury Concentration Fluctuations

Science.gov (United States)

The probability density function (PDF) of the time intervals between subsequent extreme events in atmospheric Hg0 concentration data series from different latitudes has been investigated. The Hg0 dynamic possesses a long-term memory autocorrelation function. Above a fixed thresh...

Direct photon production and PDF fits reloaded

Energy Technology Data Exchange (ETDEWEB)

Campbell, John M.; Rojo, Juan; Slade, Emma; Williams, Ciaran

2018-02-08

Direct photon production in hadronic collisions provides a handle on the gluon PDF by means of the QCD Compton scattering process. In this work we revisit the impact of direct photon production on a global PDF analysis, motivated by the recent availability of the next-to-next-to-leading (NNLO) calculation for this process. We demonstrate that the inclusion of NNLO QCD and leading-logarithmic electroweak corrections leads to a good quantitative agreement with the ATLAS measurements at 8 TeV and 13 TeV, except for the most forward rapidity region in the former case. By including the ATLAS 8 TeV direct photon production data in the NNPDF3.1 NNLO global analysis, we assess its impact on the medium-x gluon. We also study the constraining power of the direct photon production measurements on PDF fits based on different datasets, in particular on the NNPDF3.1 no-LHC and collider-only fits. We also present updated NNLO theoretical predictions for direct photon production at 13 TeV that include the constraints from the 8 TeV measurements.

Analysis of photosynthate translocation velocity and measurement of weighted average velocity in transporting pathway of crops

International Nuclear Information System (INIS)

Ge Cailin; Luo Shishi; Gong Jian; Zhang Hao; Ma Fei

1996-08-01

The translocation profile pattern of 14 C-photosynthate along the transporting pathway in crops were monitored by pulse-labelling a mature leaf with 14 CO 2 . The progressive spreading of translocation profile pattern along the sheath or stem indicates that the translocation of photosynthate along the sheath or stem proceed with a range of velocities rather than with just a single velocity. The method for measuring the weighted average velocity of photosynthate translocation along the sheath or stem was established in living crops. The weighted average velocity and the maximum velocity of photosynthate translocation along the sheath in rice and maize were measured actually. (4 figs., 3 tabs.)

Validation of Transverse Oscillation Vector Velocity Estimation In-Vivo

DEFF Research Database (Denmark)

Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten

2007-01-01

Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound (US) beam direction. This implies that a Doppler angle under examination close to 90deg results in unreliable information about the true blood direction and blood velocity. The novel...... the presented angle independent 2-D vector velocity method. The results give reason to believe that the TO method can be a useful alternative to conventional Doppler systems bringing forth new information to the US examination of blood flow....

A test of the ADV-based Reynolds flux method for in situ estimation of sediment settling velocity in a muddy estuary

Science.gov (United States)

Cartwright, Grace M.; Friedrichs, Carl T.; Smith, S. Jarrell

2013-12-01

Under conditions common in muddy coastal and estuarine environments, acoustic Doppler velocimeters (ADVs) can serve to estimate sediment settling velocity ( w s) by assuming a balance between upward turbulent Reynolds flux and downward gravitational settling. Advantages of this method include simple instrument deployment, lack of flow disturbance, and relative insensitivity to biofouling and water column stratification. Although this method is being used with increasing frequency in coastal and estuarine environments, to date it has received little direct ground truthing. This study compared in situ estimates of w s inferred by a 5-MHz ADV to independent in situ observations from a high-definition video settling column over the course of a flood tide in the bottom boundary layer of the York River estuary, Virginia, USA. The ADV-based measurements were found to agree with those of the settling column when the current speed at about 40 cm above the bed was greater than about 20 cm/s. This corresponded to periods when the estimated magnitude of the settling term in the suspended sediment continuity equation was four or more times larger than the time rate of change of concentration. For ADV observations restricted to these conditions, ADV-based estimates of w s (mean 0.48±0.04 mm/s) were highly consistent with those observed by the settling column (mean 0.45±0.02 mm/s). However, the ADV-based method for estimating w s was sensitive to the prescribed concentration of the non-settling washload, C wash. In an objective operational definition, C wash can be set equal to the lowest suspended solids concentration observed around slack water.

Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models

Science.gov (United States)

Murillo, Carol Andrea; Thorel, Luc; Caicedo, Bernardo

2009-06-01

The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge testing is a relevant method to characterize VS near the surface.

IT Department User Survey PDF Usage Report

CERN Document Server

Jones, Pete

2017-01-01

During 2016 the IT-CDA group carried out a study of IT users and their working environments and habits with the aim of understanding the user community better. This project involved interviews with users from different working backgrounds and an online survey containing questions of user devices and software preferences. A section of the questions was aimed at understanding how people handle PDF documents and this note analyses the responses to these. This analysis will help IT-CDA to better understand the PDF requirements and so help us to improve the services that rely on these documents.

On whistler-mode group velocity

International Nuclear Information System (INIS)

Sazhin, S.S.

1986-01-01

An analytical of the group velocity of whistler-mode waves propagating parallel to the magnetic field in a hot anisotropic plasma is presented. Some simple approximate formulae, which can be used for the magnetospheric applications, are derived. These formulae can predict some properties of this group velocity which were not previously recognized or were obtained by numerical methods. In particular, it is pointed out that the anisotropy tends to compensate for the influence of the electron temperature on the value of the group velocity when the wave frequency is well below the electron gyrofrequency. It is predicted, that under conditions at frequencies near the electron gyrofrequency, this velocity tends towards zero

Attenuation and velocity dispersion in the exploration seismic frequency band

Science.gov (United States)

Sun, Langqiu

In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

Feasibility of a semi-automated method for cardiac conduction velocity analysis of high-resolution activation maps

NARCIS (Netherlands)

Doshi, Ashish N.; Walton, Richard D.; Krul, Sébastien P.; de Groot, Joris R.; Bernus, Olivier; Efimov, Igor R.; Boukens, Bastiaan J.; Coronel, Ruben

2015-01-01

Myocardial conduction velocity is important for the genesis of arrhythmias. In the normal heart, conduction is primarily dependent on fiber direction (anisotropy) and may be discontinuous at sites with tissue heterogeneities (trabeculated or fibrotic tissue). We present a semi-automated method for

Exploiting LSPIV to assess debris-flow velocities in the field

Science.gov (United States)

Theule, Joshua I.; Crema, Stefano; Marchi, Lorenzo; Cavalli, Marco; Comiti, Francesco

2018-01-01

The assessment of flow velocity has a central role in quantitative analysis of debris flows, both for the characterization of the phenomenology of these processes and for the assessment of related hazards. Large-scale particle image velocimetry (LSPIV) can contribute to the assessment of surface velocity of debris flows, provided that the specific features of these processes (e.g. fast stage variations and particles up to boulder size on the flow surface) are taken into account. Three debris-flow events, each of them consisting of several surges featuring different sediment concentrations, flow stages, and velocities, have been analysed at the inlet of a sediment trap in a stream in the eastern Italian Alps (Gadria Creek). Free software has been employed for preliminary treatment (orthorectification and format conversion) of video-recorded images as well as for LSPIV application. Results show that LSPIV velocities are consistent with manual measurements of the orthorectified imagery and with front velocity measured from the hydrographs in a channel recorded approximately 70 m upstream of the sediment trap. Horizontal turbulence, computed as the standard deviation of the flow directions at a given cross section for a given surge, proved to be correlated with surface velocity and with visually estimated sediment concentration. The study demonstrates the effectiveness of LSPIV in the assessment of surface velocity of debris flows and permit the most crucial aspects to be identified in order to improve the accuracy of debris-flow velocity measurements.

Calculation of radon concentration in water by toluene extraction method

Energy Technology Data Exchange (ETDEWEB)

Saito, Masaaki [Tokyo Metropolitan Isotope Research Center (Japan)

1997-02-01

Noguchi method and Horiuchi method have been used as the calculation method of radon concentration in water. Both methods have two problems in the original, that is, the concentration calculated is changed by the extraction temperature depend on the incorrect solubility data and the concentration calculated are smaller than the correct values, because the radon calculation equation does not true to the gas-liquid equilibrium theory. However, the two problems are solved by improving the radon equation. I presented the Noguchi-Saito equation and the constant B of Horiuchi-Saito equation. The calculating results by the improved method showed about 10% of error. (S.Y.)

Estimating the Wet-Rock P-Wave Velocity from the Dry-Rock P-Wave Velocity for Pyroclastic Rocks

Science.gov (United States)

Kahraman, Sair; Fener, Mustafa; Kilic, Cumhur Ozcan

2017-07-01

Seismic methods are widely used for the geotechnical investigations in volcanic areas or for the determination of the engineering properties of pyroclastic rocks in laboratory. Therefore, developing a relation between the wet- and dry-rock P-wave velocities will be helpful for engineers when evaluating the formation characteristics of pyroclastic rocks. To investigate the predictability of the wet-rock P-wave velocity from the dry-rock P-wave velocity for pyroclastic rocks P-wave velocity measurements were conducted on 27 different pyroclastic rocks. In addition, dry-rock S-wave velocity measurements were conducted. The test results were modeled using Gassmann's and Wood's theories and it was seen that estimates for saturated P-wave velocity from the theories fit well measured data. For samples having values of less and greater than 20%, practical equations were derived for reliably estimating wet-rock P-wave velocity as function of dry-rock P-wave velocity.

Probability Density Function Method for Observing Reconstructed Attractor Structure

Institute of Scientific and Technical Information of China (English)

陆宏伟; 陈亚珠; 卫青

2004-01-01

Probability density function (PDF) method is proposed for analysing the structure of the reconstructed attractor in computing the correlation dimensions of RR intervals of ten normal old men. PDF contains important information about the spatial distribution of the phase points in the reconstructed attractor. To the best of our knowledge, it is the first time that the PDF method is put forward for the analysis of the reconstructed attractor structure. Numerical simulations demonstrate that the cardiac systems of healthy old men are about 6 - 6.5 dimensional complex dynamical systems. It is found that PDF is not symmetrically distributed when time delay is small, while PDF satisfies Gaussian distribution when time delay is big enough. A cluster effect mechanism is presented to explain this phenomenon. By studying the shape of PDFs, that the roles played by time delay are more important than embedding dimension in the reconstruction is clearly indicated. Results have demonstrated that the PDF method represents a promising numerical approach for the observation of the reconstructed attractor structure and may provide more information and new diagnostic potential of the analyzed cardiac system.

Tailoring group velocity by topology optimization

DEFF Research Database (Denmark)

Stainko, Roman; Sigmund, Ole

2007-01-01

The paper describes a systematic method for the tailoring of dispersion properties of slab-based photonic crystal waveguides. The method is based on the topology optimization method which consists in repeated finite element frequency domain analyses. The goal of the optimization process is to come...... up with slow light, zero group velocity dispersion photonic waveguides or photonic waveguides with tailored dispersion properties for dispersion compensation purposes. An example concerning the design of a wide bandwidth, constant low group velocity waveguide demonstrate the e±ciency of the method....

Implicit and explicit schemes for mass consistency preservation in hybrid particle/finite-volume algorithms for turbulent reactive flows

International Nuclear Information System (INIS)

Popov, Pavel P.; Pope, Stephen B.

2014-01-01

This work addresses the issue of particle mass consistency in Large Eddy Simulation/Probability Density Function (LES/PDF) methods for turbulent reactive flows. Numerical schemes for the implicit and explicit enforcement of particle mass consistency (PMC) are introduced, and their performance is examined in a representative LES/PDF application, namely the Sandia–Sydney Bluff-Body flame HM1. A new combination of interpolation schemes for velocity and scalar fields is found to better satisfy PMC than multilinear and fourth-order Lagrangian interpolation. A second-order accurate time-stepping scheme for stochastic differential equations (SDE) is found to improve PMC relative to Euler time stepping, which is the first time that a second-order scheme is found to be beneficial, when compared to a first-order scheme, in an LES/PDF application. An explicit corrective velocity scheme for PMC enforcement is introduced, and its parameters optimized to enforce a specified PMC criterion with minimal corrective velocity magnitudes

Reliability and Validity of the Load-Velocity Relationship to Predict the 1RM Back Squat.

Science.gov (United States)

Banyard, Harry G; Nosaka, Kazunori; Haff, G Gregory

2017-07-01

Banyard, HG, Nosaka, K, and Haff, GG. Reliability and validity of the load-velocity relationship to predict the 1RM back squat. J Strength Cond Res 31(7): 1897-1904, 2017-This study investigated the reliability and validity of the load-velocity relationship to predict the free-weight back squat one repetition maximum (1RM). Seventeen strength-trained males performed three 1RM assessments on 3 separate days. All repetitions were performed to full depth with maximal concentric effort. Predicted 1RMs were calculated by entering the mean concentric velocity of the 1RM (V1RM) into an individualized linear regression equation, which was derived from the load-velocity relationship of 3 (20, 40, 60% of 1RM), 4 (20, 40, 60, 80% of 1RM), or 5 (20, 40, 60, 80, 90% of 1RM) incremental warm-up sets. The actual 1RM (140.3 ± 27.2 kg) was very stable between 3 trials (ICC = 0.99; SEM = 2.9 kg; CV = 2.1%; ES = 0.11). Predicted 1RM from 5 warm-up sets up to and including 90% of 1RM was the most reliable (ICC = 0.92; SEM = 8.6 kg; CV = 5.7%; ES = -0.02) and valid (r = 0.93; SEE = 10.6 kg; CV = 7.4%; ES = 0.71) of the predicted 1RM methods. However, all predicted 1RMs were significantly different (p ≤ 0.05; ES = 0.71-1.04) from the actual 1RM. Individual variation for the actual 1RM was small between trials ranging from -5.6 to 4.8% compared with the most accurate predictive method up to 90% of 1RM, which was more variable (-5.5 to 27.8%). Importantly, the V1RM (0.24 ± 0.06 m·s) was unreliable between trials (ICC = 0.42; SEM = 0.05 m·s; CV = 22.5%; ES = 0.14). The load-velocity relationship for the full depth free-weight back squat showed moderate reliability and validity but could not accurately predict 1RM, which was stable between trials. Thus, the load-velocity relationship 1RM prediction method used in this study cannot accurately modify sessional training loads because of large V1RM variability.

Extra Dimensions: 3D in PDF Documentation

International Nuclear Information System (INIS)

Graf, Norman A

2012-01-01

Experimental science is replete with multi-dimensional information which is often poorly represented by the two dimensions of presentation slides and print media. Past efforts to disseminate such information to a wider audience have failed for a number of reasons, including a lack of standards which are easy to implement and have broad support. Adobe's Portable Document Format (PDF) has in recent years become the de facto standard for secure, dependable electronic information exchange. It has done so by creating an open format, providing support for multiple platforms and being reliable and extensible. By providing support for the ECMA standard Universal 3D (U3D) and the ISO PRC file format in its free Adobe Reader software, Adobe has made it easy to distribute and interact with 3D content. Until recently, Adobe's Acrobat software was also capable of incorporating 3D content into PDF files from a variety of 3D file formats, including proprietary CAD formats. However, this functionality is no longer available in Acrobat X, having been spun off to a separate company. Incorporating 3D content now requires the additional purchase of a separate plug-in. In this talk we present alternatives based on open source libraries which allow the programmatic creation of 3D content in PDF format. While not providing the same level of access to CAD files as the commercial software, it does provide physicists with an alternative path to incorporate 3D content into PDF files from such disparate applications as detector geometries from Geant4, 3D data sets, mathematical surfaces or tesselated volumes.

High - velocity water jet impact on concrete samples

Czech Academy of Sciences Publication Activity Database

Mádr, V.; Uhlář, R.; Hlaváč, L. M.; Sitek, Libor; Foldyna, Josef; Hela, R.; Bodnárová, L.; Kaličinský, J.

2009-01-01

Roč. 2, č. 4 (2009), s. 43-48 ISSN 2067-3809 Institutional research plan: CEZ:AV0Z30860518 Keywords : water jet * concrete * depth of penetration * disintegration volume Subject RIV: JM - Building Engineering http://acta.fih.upt.ro/pdf/2009-4/ACTA-2009-4-08.pdf

A new phase coding method using a slice selection gradient for high speed flow velocity meaurements in NMR tomography

International Nuclear Information System (INIS)

Oh, C.H.; Cho, Z.H.; California Univ., Irvine

1986-01-01

A new phase coding method using a selection gradient for high speed NMR flow velocity measurements is introduced and discussed. To establish a phase-velocity relationship of flow under the slice selection gradient and spin-echo RF pulse, the Bloch equation was numerically solved under the assumption that only one directional flow exists, i.e. in the direction of slice selection. Details of the numerical solution of the Bloch equation and techniques related to the numerical computations are also given. Finally, using the numerical calculation, high speed flow velocity measurement was attempted and found to be in good agreement with other complementary controlled measurements. (author)

Experiments and CFD Modelling of Turbulent Mass Transfer in a Mixing Channel

DEFF Research Database (Denmark)

Hjertager Osenbroch, Lene Kristin; Hjertager, Bjørn H.; Solberg, Tron

2006-01-01

. Three different flow cases are studied. The 2D numerical predictions of the mixing channel show that none of the k-ε turbulence models tested is suitable for the flow cases studied here. The turbulent Schmidt number is reduced to obtain a better agreement between measured and predicted mean......Experiments are carried out for passive mixing in order to obtain local mean and turbulent velocities and concentrations. The mixing takes place in a square channel with two inlets separated by a block. A combined PIV/PLIF technique is used to obtain instantaneous velocity and concentration fields...... and fluctuating concentrations. The multi-peak presumed PDF mixing model is tested....

Maximal intended velocity training induces greater gains in bench press performance than deliberately slower half-velocity training.

Science.gov (United States)

González-Badillo, Juan José; Rodríguez-Rosell, David; Sánchez-Medina, Luis; Gorostiaga, Esteban M; Pareja-Blanco, Fernando

2014-01-01

The purpose of this study was to compare the effect on strength gains of two isoinertial resistance training (RT) programmes that only differed in actual concentric velocity: maximal (MaxV) vs. half-maximal (HalfV) velocity. Twenty participants were assigned to a MaxV (n = 9) or HalfV (n = 11) group and trained 3 times per week during 6 weeks using the bench press (BP). Repetition velocity was controlled using a linear velocity transducer. A complementary study (n = 10) aimed to analyse whether the acute metabolic (blood lactate and ammonia) and mechanical response (velocity loss) was different between the MaxV and HalfV protocols used. Both groups improved strength performance from pre- to post-training, but MaxV resulted in significantly greater gains than HalfV in all variables analysed: one-repetition maximum (1RM) strength (18.2 vs. 9.7%), velocity developed against all (20.8 vs. 10.0%), light (11.5 vs. 4.5%) and heavy (36.2 vs. 17.3%) loads common to pre- and post-tests. Light and heavy loads were identified with those moved faster or slower than 0.80 m · s(-1) (∼ 60% 1RM in BP). Lactate tended to be significantly higher for MaxV vs. HalfV, with no differences observed for ammonia which was within resting values. Both groups obtained the greatest improvements at the training velocities (≤ 0.80 m · s(-1)). Movement velocity can be considered a fundamental component of RT intensity, since, for a given %1RM, the velocity at which loads are lifted largely determines the resulting training effect. BP strength gains can be maximised when repetitions are performed at maximal intended velocity.

Edgeworth Expansion Based Model for the Convolutional Noise pdf

Directory of Open Access Journals (Sweden)

Yonatan Rivlin

2014-01-01

Full Text Available Recently, the Edgeworth expansion up to order 4 was used to represent the convolutional noise probability density function (pdf in the conditional expectation calculations where the source pdf was modeled with the maximum entropy density approximation technique. However, the applied Lagrange multipliers were not the appropriate ones for the chosen model for the convolutional noise pdf. In this paper we use the Edgeworth expansion up to order 4 and up to order 6 to model the convolutional noise pdf. We derive the appropriate Lagrange multipliers, thus obtaining new closed-form approximated expressions for the conditional expectation and mean square error (MSE as a byproduct. Simulation results indicate hardly any equalization improvement with Edgeworth expansion up to order 4 when using optimal Lagrange multipliers over a nonoptimal set. In addition, there is no justification for using the Edgeworth expansion up to order 6 over the Edgeworth expansion up to order 4 for the 16QAM and easy channel case. However, Edgeworth expansion up to order 6 leads to improved equalization performance compared to the Edgeworth expansion up to order 4 for the 16QAM and hard channel case as well as for the case where the 64QAM is sent via an easy channel.

In Vivo Validation of a Blood Vector Velocity Estimator with MR Angiography

DEFF Research Database (Denmark)

Hansen, Kristoffer Lindskov; Udesen, Jesper; Thomsen, Carsten

2009-01-01

Conventional Doppler methods for blood velocity estimation only estimate the velocity component along the ultrasound beam direction. This implies that a Doppler angle under examination close to 90° results in unreliable information about the true blood direction and blood velocity. The novel method...... indicate that reliable vector velocity estimates can be obtained in vivo using the presented angle-independent 2-D vector velocity method. The TO method can be a useful alternative to conventional Doppler systems by avoiding the angle artifact, thus giving quantitative velocity information....

Stellar magnetometry and Zeeman-Doppler imaging in exo-planets research using the radial velocity method

International Nuclear Information System (INIS)

Hebrard, Elodie

2015-01-01

Forthcoming instruments dedicated to exo-planets detection through the radial velocity method are numerous, and increasingly more accurate. However this method is indirect: orbiting planets are detected and characterised from variations on the spectrum of the host star. We are therefore sensitive to all activity phenomena impacting the spectrum and producing a radial velocity signal (pulsation, granulation, spots, magnetic cycle...). The detection of rocky Earth-like planets around main-sequence stars, and of hot Jupiters into young systems, are currently limited by the intrinsic magnetic activity of the host stars. The radial velocity fluctuations caused by activity (activity jitter) can easily mimic and hide signals from such planets, whose amplitude is of a few m/s and hundreds of m/s, respectively. As a result, the detection threshold of exo-planets is largely set by the stellar activity level. Currently, efforts are invested to overcome this intrinsic limitation. During my PhD, I studied how to take advantage of imaging tomographic techniques (Zeeman-Doppler imaging, ZDI) to characterize stellar activity and magnetic field topologies, ultimately allowing us to filter out the activity jitter. My work is based on spectro-polarimetric observations of a sample of weakly-active M-dwarfs, and young active T Tauri stars. Using a modified version of ZDI, we are able to reconstruct the distribution of active regions, and then model the induced stellar signal allowing us to clean RV curves from the activity jitter. First tests demonstrate that this technique can be efficient enough to recover the planet signal, especially for the more active ones. (author)

Portable method of measuring gaseous acetone concentrations.

Science.gov (United States)

Worrall, Adam D; Bernstein, Jonathan A; Angelopoulos, Anastasios P

2013-08-15

Measurement of acetone in human breath samples has been previously shown to provide significant non-invasive diagnostic insight into the control of a patient's diabetic condition. In patients with diabetes mellitus, the body produces excess amounts of ketones such as acetone, which are then exhaled during respiration. Using various breath analysis methods has allowed for the accurate determination of acetone concentrations in exhaled breath. However, many of these methods require instrumentation and pre-concentration steps not suitable for point-of-care use. We have found that by immobilizing resorcinol reagent into a perfluorosulfonic acid polymer membrane, a controlled organic synthesis reaction occurs with acetone in a dry carrier gas. The immobilized, highly selective product of this reaction (a flavan) is found to produce a visible spectrum color change which could measure acetone concentrations to less than ppm. We here demonstrate how this approach can be used to produce a portable optical sensing device for real-time, non-invasive acetone analysis. Copyright © 2013 Elsevier B.V. All rights reserved.

PDF fit in the fixed-flavour-number scheme

International Nuclear Information System (INIS)

Alekhin, S.; Bluemlein, J.; Moch, S.

2012-02-01

We discuss the heavy-quark contribution to deep inelastic scattering in the scheme with n f =3;4;5 fixed flavors. Based on the recent ABM11 PDF analysis of world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process with the running-mass definition for heavy quarks we show that fixed flavor number scheme is sufficient for describing the deep-inelastic-scattering data in the entire kinematic range. We compare with other PDF sets and comment on the implications for measuring the strong coupling constant α s (M Z ).

A noninvasive method for measuring the velocity of diffuse hydrothermal flow by tracking moving refractive index anomalies

Science.gov (United States)

Mittelstaedt, Eric; Davaille, Anne; van Keken, Peter E.; Gracias, Nuno; Escartin, Javier

2010-10-01

Diffuse flow velocimetry (DFV) is introduced as a new, noninvasive, optical technique for measuring the velocity of diffuse hydrothermal flow. The technique uses images of a motionless, random medium (e.g., rocks) obtained through the lens of a moving refraction index anomaly (e.g., a hot upwelling). The method works in two stages. First, the changes in apparent background deformation are calculated using particle image velocimetry (PIV). The deformation vectors are determined by a cross correlation of pixel intensities across consecutive images. Second, the 2-D velocity field is calculated by cross correlating the deformation vectors between consecutive PIV calculations. The accuracy of the method is tested with laboratory and numerical experiments of a laminar, axisymmetric plume in fluids with both constant and temperature-dependent viscosity. Results show that average RMS errors are ˜5%-7% and are most accurate in regions of pervasive apparent background deformation which is commonly encountered in regions of diffuse hydrothermal flow. The method is applied to a 25 s video sequence of diffuse flow from a small fracture captured during the Bathyluck'09 cruise to the Lucky Strike hydrothermal field (September 2009). The velocities of the ˜10°C-15°C effluent reach ˜5.5 cm/s, in strong agreement with previous measurements of diffuse flow. DFV is found to be most accurate for approximately 2-D flows where background objects have a small spatial scale, such as sand or gravel.

Galilean-invariant preconditioned central-moment lattice Boltzmann method without cubic velocity errors for efficient steady flow simulations

Science.gov (United States)

Hajabdollahi, Farzaneh; Premnath, Kannan N.

2018-05-01

Lattice Boltzmann (LB) models used for the computation of fluid flows represented by the Navier-Stokes (NS) equations on standard lattices can lead to non-Galilean-invariant (GI) viscous stress involving cubic velocity errors. This arises from the dependence of their third-order diagonal moments on the first-order moments for standard lattices, and strategies have recently been introduced to restore Galilean invariance without such errors using a modified collision operator involving corrections to either the relaxation times or the moment equilibria. Convergence acceleration in the simulation of steady flows can be achieved by solving the preconditioned NS equations, which contain a preconditioning parameter that can be used to tune the effective sound speed, and thereby alleviating the numerical stiffness. In the present paper, we present a GI formulation of the preconditioned cascaded central-moment LB method used to solve the preconditioned NS equations, which is free of cubic velocity errors on a standard lattice, for steady flows. A Chapman-Enskog analysis reveals the structure of the spurious non-GI defect terms and it is demonstrated that the anisotropy of the resulting viscous stress is dependent on the preconditioning parameter, in addition to the fluid velocity. It is shown that partial correction to eliminate the cubic velocity defects is achieved by scaling the cubic velocity terms in the off-diagonal third-order moment equilibria with the square of the preconditioning parameter. Furthermore, we develop additional corrections based on the extended moment equilibria involving gradient terms with coefficients dependent locally on the fluid velocity and the preconditioning parameter. Such parameter dependent corrections eliminate the remaining truncation errors arising from the degeneracy of the diagonal third-order moments and fully restore Galilean invariance without cubic defects for the preconditioned LB scheme on a standard lattice. Several

Natural tracer test simulation by stochastic particle tracking method

International Nuclear Information System (INIS)

Ackerer, P.; Mose, R.; Semra, K.

1990-01-01

Stochastic particle tracking methods are well adapted to 3D transport simulations where discretization requirements of other methods usually cannot be satisfied. They do need a very accurate approximation of the velocity field. The described code is based on the mixed hybrid finite element method (MHFEM) to calculated the piezometric and velocity field. The random-walk method is used to simulate mass transport. The main advantages of the MHFEM over FD or FE are the simultaneous calculation of pressure and velocity, which are considered as unknowns; the possibility of interpolating velocities everywhere; and the continuity of the normal component of the velocity vector from one element to another. For these reasons, the MHFEM is well adapted for particle tracking methods. After a general description of the numerical methods, the model is used to simulate the observations made during the Twin Lake Tracer Test in 1983. A good match is found between observed and simulated heads and concentrations. (Author) (12 refs., 4 figs.)

Growth of binary solid solution single crystals and calculation of melt surface displacement velocity

International Nuclear Information System (INIS)

Agamaliyev, Z.A.; Tahirov, V.I.; Hasanov, Z.Y.; Quliyev, A.F.

2007-01-01

A binary solid solution single crystal growth method has been worked out. Cylinder feeding alloy with complex content distribution and truncated cone crucible are used. Second component distribution coefficient is more than unit. Content distribution along grown crystal is found by solving continuity equation. After reaching dynamic equilibrium state second component concentration in grown crystal is saturated the value of which is less than the average ona in the feeding alloy. Using the method Ge-Si perfect single crystals has been grown. Calculation method of melt surface displacement velocity has been offered as well

Application of Acoustic and Optic Methods for Estimating Suspended-Solids Concentrations in the St. Lucie River Estuary, Florida

Science.gov (United States)

Patino, Eduardo; Byrne, Michael J.

2004-01-01

Acoustic and optic methods were applied to estimate suspended-solids concentrations in the St. Lucie River Estuary, southeastern Florida. Acoustic Doppler velocity meters were installed at the North Fork, Speedy Point, and Steele Point sites within the estuary. These sites provide varying flow, salinity, water-quality, and channel cross-sectional characteristics. The monitoring site at Steele Point was not used in the analyses because repeated instrument relocations (due to bridge construction) prevented a sufficient number of samples from being collected at the various locations. Acoustic and optic instruments were installed to collect water velocity, acoustic backscatter strength (ABS), and turbidity data that were used to assess the feasibility of estimating suspended-solids concentrations in the estuary. Other data collected at the monitoring sites include tidal stage, salinity, temperature, and periodic discharge measurements. Regression analyses were used to determine the relations of suspended-solids concentration to ABS and suspended-solids concentration to turbidity at the North Fork and Speedy Point sites. For samples used in regression analyses, measured suspended-solids concentrations at the North Fork and Speedy Point sites ranged from 3 to 37 milligrams per liter, and organic content ranged from 50 to 83 percent. Corresponding salinity for these samples ranged from 0.12 to 22.7 parts per thousand, and corresponding temperature ranged from 19.4 to 31.8 ?C. Relations determined using this technique are site specific and only describe suspended-solids concentrations at locations where data were collected. The suspended-solids concentration to ABS relation resulted in correlation coefficients of 0.78 and 0.63 at the North Fork and Speedy Point sites, respectively. The suspended-solids concentration to turbidity relation resulted in correlation coefficients of 0.73 and 0.89 at the North Fork and Speedy Point sites, respectively. The adequacy of the

A simple flow-concentration modelling method for integrating water ...

African Journals Online (AJOL)

A simple flow-concentration modelling method for integrating water quality and ... flow requirements are assessed for maintenance low flow, drought low flow ... the instream concentrations of chemical constituents that will arise from different ...

Method of concentrating oil shale by flotation

Energy Technology Data Exchange (ETDEWEB)

Larsson, M

1941-01-28

A method is described of concentrating oil shale by flotation. It is characterized by grinding the shale to a grain size which, roughly speaking, is less than 0.06 mm. and more conveniently should be less than 0.05 mm., and followed by flotation. During the process the brown foam formed is separated as concentrate, while the black-brown to all-black foam is separated as a middle product, ground fine again, and thereafter floated once more. The patent contains five additional claims.

Fulltext PDF

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

2004-11-03

Nov 3, 2004 ... clouds decrease with their increasing random velocities. These fast clouds .... where the velocities of the absorption lines were due to systematic motions. .... This is expected since we are sampling relatively small path lengths ...

Noncommutative nature of the addition of noncollinear velocities in special relativity and the geometric phase method (commemorating the publication centennial of A Sommerfeld's work)

International Nuclear Information System (INIS)

Malykin, Grigorii B

2010-01-01

In 1909, Arnold Sommerfeld used geometric calculations to show that the relativistic addition of two noncollinear velocities on an imaginary-radius sphere is a noncommutative operation. Sommerfeld was the first to use the geometric phase method to calculate the angle between the resulting velocities depending on the order in which they are added. For this, he related the value of this angle to the excess of the spherical triangle formed by the two original velocities and their sum. In 1931, Sommerfeld applied his method to analyze the Thomas precession. (from the history of physics)

Peculiar velocity measurement in a clumpy universe

Science.gov (United States)

Habibi, Farhang; Baghram, Shant; Tavasoli, Saeed

Aims: In this work, we address the issue of peculiar velocity measurement in a perturbed Friedmann universe using the deviations from measured luminosity distances of standard candles from background FRW universe. We want to show and quantify the statement that in intermediate redshifts (0.5 deviations from the background FRW model are not uniquely governed by peculiar velocities. Luminosity distances are modified by gravitational lensing. We also want to indicate the importance of relativistic calculations for peculiar velocity measurement at all redshifts. Methods: For this task, we discuss the relativistic correction on luminosity distance and redshift measurement and show the contribution of each of the corrections as lensing term, peculiar velocity of the source and Sachs-Wolfe effect. Then, we use the SNe Ia sample of Union 2, to investigate the relativistic effects, we consider. Results: We show that, using the conventional peculiar velocity method, that ignores the lensing effect, will result in an overestimate of the measured peculiar velocities at intermediate redshifts. Here, we quantify this effect. We show that at low redshifts the lensing effect is negligible compare to the effect of peculiar velocity. From the observational point of view, we show that the uncertainties on luminosity of the present SNe Ia data prevent us from precise measuring the peculiar velocities even at low redshifts (z < 0.2).

Microseismic Velocity Imaging of the Fracturing Zone

Science.gov (United States)

Zhang, H.; Chen, Y.

2015-12-01

Hydraulic fracturing of low permeability reservoirs can induce microseismic events during fracture development. For this reason, microseismic monitoring using sensors on surface or in borehole have been widely used to delineate fracture spatial distribution and to understand fracturing mechanisms. It is often the case that the stimulated reservoir volume (SRV) is determined solely based on microseismic locations. However, it is known that for some fracture development stage, long period long duration events, instead of microseismic events may be associated. In addition, because microseismic events are essentially weak and there exist different sources of noise during monitoring, some microseismic events could not be detected and thus located. Therefore the estimation of the SRV is biased if it is solely determined by microseismic locations. With the existence of fluids and fractures, the seismic velocity of reservoir layers will be decreased. Based on this fact, we have developed a near real time seismic velocity tomography method to characterize velocity changes associated with fracturing process. The method is based on double-difference seismic tomography algorithm to image the fracturing zone where microseismic events occur by using differential arrival times from microseismic event pairs. To take into account varying data distribution for different fracking stages, the method solves the velocity model in the wavelet domain so that different scales of model features can be obtained according to different data distribution. We have applied this real time tomography method to both acoustic emission data from lab experiment and microseismic data from a downhole microseismic monitoring project for shale gas hydraulic fracturing treatment. The tomography results from lab data clearly show the velocity changes associated with different rock fracturing stages. For the field data application, it shows that microseismic events are located in low velocity anomalies. By

Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

International Nuclear Information System (INIS)

Nishio, R.; Ikeda, M.; Sasaki, R.; Ohashi, S.

2011-01-01

The hybrid magnetically levitated carrying system is developed. Control method of running velocity of the carrier is studied. Running velocity is controlled by current of the propulsion coils. Propulsion characteristcs are improved. We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

Study on control method of running velocity for the permanent magnet-HTSC hybrid magnetically levitated conveyance system

Energy Technology Data Exchange (ETDEWEB)

Nishio, R.; Ikeda, M.; Sasaki, R. [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan); Ohashi, S., E-mail: ohashi@kansai-u.ac.jp [Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680 (Japan)

2011-11-15

The hybrid magnetically levitated carrying system is developed. Control method of running velocity of the carrier is studied. Running velocity is controlled by current of the propulsion coils. Propulsion characteristcs are improved. We have developed the magnetically levitated carrying system. In this system, pinning force of high temperature bulk super conductor (HTSC) is used for the levitation and guidance. Four HTSCs are installed on the carrier. The magnetic rail is set on the ground, and flux from the magnetic rail is pinned by HTSCs. To increase levitation force, repulsive force of the permanent magnet is used. The hybrid levitation system is composed. The permanent magnet is installed under the load stage of the carrier. Repulsive force by the permanent magnet between the load stage on the carrier and the magnetic rail on the ground is used to support the load weight. Levitation and guidance one by pinning effect of the YBaCuO HTSC in the carrier is used to levitate the carrier body. The load stage is separated from the carrier flame and can move freely for vertical direction levitation. For the propulsion system, electromagnet is installed on the surface of the magnetic rail. In this paper, control method of running velocity of the carrier is studied. Propulsion force is given as follows; Air core copper coils are installed on the magnetic rail. Interaction between current of these coils and permanent magnets on the carrier generates propulsion force. Running velocity is controlled by current of the propulsion coils. It is also changed by position of the carrier and the load weight. From the results, stability of the propulsion system is given, and propulsion characteristics are improved.

PDF fit in the fixed-flavour-number scheme

Energy Technology Data Exchange (ETDEWEB)

Alekhin, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Institute for High Energy Physics, Moscow (Russian Federation); Bluemlein, J.; Moch, S. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

2012-02-15

We discuss the heavy-quark contribution to deep inelastic scattering in the scheme with n{sub f}=3;4;5 fixed flavors. Based on the recent ABM11 PDF analysis of world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process with the running-mass definition for heavy quarks we show that fixed flavor number scheme is sufficient for describing the deep-inelastic-scattering data in the entire kinematic range. We compare with other PDF sets and comment on the implications for measuring the strong coupling constant {alpha}{sub s}(M{sub Z}).

Computational analysis for velocity slip and diffusion species with carbon nanotubes

Science.gov (United States)

Hayat, T.; Hussain, Zakir; Alsaedi, A.; Hobiny, A.

This article addresses a computational study for carbon nanotubes with diffusion species. Mathematical analysis and modeling are formulated in the presence of slip effect, Darcy porous medium and chemical species. Diffusion coefficients are accounted as equal amount. Optimal Homotopy Analysis Method (OHAM) is implemented in taking care for convergence control parameters. Residual errors and its graphs are plotted for CNTs nanofluids. The current data is compared with the previous published work. The results are found in favorable agreement. Physically interesting parameters are highlighted. The velocity is dominated for MWCNT than SWCNT. The velocity profile increases for power index when m > 1 while opposite trend is observed for power index when m skin friction coefficient and reverse trend is noticed for slip parameter and wall thickness parameter. Opposite behavior is noticed for concentration profile at surface for homogenous-heterogeneous reactions parameters.

Sparse PDF maps for non-linear multi-resolution image operations

KAUST Repository

Hadwiger, Markus

2012-11-01

We introduce a new type of multi-resolution image pyramid for high-resolution images called sparse pdf maps (sPDF-maps). Each pyramid level consists of a sparse encoding of continuous probability density functions (pdfs) of pixel neighborhoods in the original image. The encoded pdfs enable the accurate computation of non-linear image operations directly in any pyramid level with proper pre-filtering for anti-aliasing, without accessing higher or lower resolutions. The sparsity of sPDF-maps makes them feasible for gigapixel images, while enabling direct evaluation of a variety of non-linear operators from the same representation. We illustrate this versatility for antialiased color mapping, O(n) local Laplacian filters, smoothed local histogram filters (e.g., median or mode filters), and bilateral filters. © 2012 ACM.

Evaluation of scalar mixing and time scale models in PDF simulations of a turbulent premixed flame

Energy Technology Data Exchange (ETDEWEB)

Stoellinger, Michael; Heinz, Stefan [Department of Mathematics, University of Wyoming, Laramie, WY (United States)

2010-09-15

Numerical simulation results obtained with a transported scalar probability density function (PDF) method are presented for a piloted turbulent premixed flame. The accuracy of the PDF method depends on the scalar mixing model and the scalar time scale model. Three widely used scalar mixing models are evaluated: the interaction by exchange with the mean (IEM) model, the modified Curl's coalescence/dispersion (CD) model and the Euclidean minimum spanning tree (EMST) model. The three scalar mixing models are combined with a simple model for the scalar time scale which assumes a constant C{sub {phi}}=12 value. A comparison of the simulation results with available measurements shows that only the EMST model calculates accurately the mean and variance of the reaction progress variable. An evaluation of the structure of the PDF's of the reaction progress variable predicted by the three scalar mixing models confirms this conclusion: the IEM and CD models predict an unrealistic shape of the PDF. Simulations using various C{sub {phi}} values ranging from 2 to 50 combined with the three scalar mixing models have been performed. The observed deficiencies of the IEM and CD models persisted for all C{sub {phi}} values considered. The value C{sub {phi}}=12 combined with the EMST model was found to be an optimal choice. To avoid the ad hoc choice for C{sub {phi}}, more sophisticated models for the scalar time scale have been used in simulations using the EMST model. A new model for the scalar time scale which is based on a linear blending between a model for flamelet combustion and a model for distributed combustion is developed. The new model has proven to be very promising as a scalar time scale model which can be applied from flamelet to distributed combustion. (author)

A Practical Tuning Method for the Robust PID Controller with Velocity Feed-Back

Directory of Open Access Journals (Sweden)

Emre Sariyildiz

2015-08-01

Full Text Available Proportional-Integral-Derivative (PID control is the most widely used control method in industrial and academic applications due to its simplicity and efficiency. Several different control methods/algorithms have been proposed to tune the gains of PID controllers. However, the conventional tuning methods do not have sufficient performance and simplicity for practical applications, such as robotics and motion control. The performance of motion control systems may significantly deteriorate by the nonlinear plant uncertainties and unknown external disturbances, such as inertia variations, friction, external loads, etc., i.e., there may be a significant discrepancy between the simulation and experiment if the robustness is not considered in the design of PID controllers. This paper proposes a novel practical tuning method for the robust PID controller with velocity feed-back for motion control systems. The main advantages of the proposed method are the simplicity and efficiency in practical applications, i.e., a high performance robust motion control system can be easily designed by properly tuning conventional PID controllers. The validity of the proposal is verified by giving simulation and experimental results.

Keynesian multiplier versus velocity of money

Science.gov (United States)

Wang, Yougui; Xu, Yan; Liu, Li

2010-08-01

In this paper we present the relation between Keynesian multiplier and the velocity of money circulation in a money exchange model. For this purpose we modify the original exchange model by constructing the interrelation between income and expenditure. The random exchange yields an agent's income, which along with the amount of money he processed determines his expenditure. In this interactive process, both the circulation of money and Keynesian multiplier effect can be formulated. The equilibrium values of Keynesian multiplier are demonstrated to be closely related to the velocity of money. Thus the impacts of macroeconomic policies on aggregate income can be understood by concentrating solely on the variations of money circulation.

Sparse PDF Volumes for Consistent Multi-Resolution Volume Rendering

KAUST Repository

Sicat, Ronell Barrera

2014-12-31

This paper presents a new multi-resolution volume representation called sparse pdf volumes, which enables consistent multi-resolution volume rendering based on probability density functions (pdfs) of voxel neighborhoods. These pdfs are defined in the 4D domain jointly comprising the 3D volume and its 1D intensity range. Crucially, the computation of sparse pdf volumes exploits data coherence in 4D, resulting in a sparse representation with surprisingly low storage requirements. At run time, we dynamically apply transfer functions to the pdfs using simple and fast convolutions. Whereas standard low-pass filtering and down-sampling incur visible differences between resolution levels, the use of pdfs facilitates consistent results independent of the resolution level used. We describe the efficient out-of-core computation of large-scale sparse pdf volumes, using a novel iterative simplification procedure of a mixture of 4D Gaussians. Finally, our data structure is optimized to facilitate interactive multi-resolution volume rendering on GPUs.

VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD

Directory of Open Access Journals (Sweden)

Johan Debayle

2011-05-01

Full Text Available An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.

Numerical evaluation of the five sensor probe method for measurement of local interfacial area concentration of cap bubbles

International Nuclear Information System (INIS)

Euh, D.J.; Yun, B.J.; Song, C.H.; Kwon, T.S.; Chung, M.K.; Lee, U.C.

2000-01-01

The interfacial area concentration (IAC) is one of the most important parameters in the two-fluid model for two-phase flow analysis. The IAC can be measured by a local conductivity probe method that uses the difference of conductivity between water and air/steam. The number of sensors in the conductivity probe may be differently chosen by considering the flow regime of two-phase flow. The four sensor conductivity probe method predicts the IAC without any assumptions of the bubble shape. The local IAC can be obtained by measuring the three dimensional velocity vector elements at the measuring point, and the directional cosines of the sensors. The five sensor conductivity probe method proposed in this study is based on the four sensor probe method. With the five sensor probe, the local IAC for a given referred measuring area of the probe can be predicted more exactly. In this paper, the mathematical approach of the five sensor probe method for measuring the IAC is described, and a numerical simulation is carried out for ideal cap bubbles of which the sizes and locations are determined by a random number generator. (author)

A Numerical Method for Predicting Rayleigh Surface Wave Velocity in Anisotropic Crystals (Postprint)

Science.gov (United States)

2017-09-05

velocity, preventing the use of gradient-based optimization routines. The typical approach to solving this problem is to perform the inverse many times...is dependent on the wave velocity. However, the wave velocity is unknown at this point, which means p and v must be determined simultaneously . One way...defined as: Z=−iBA−1 (11) where A is the matrix formed by combining the displacement vectors, a into a single matrix. The inverse is guaranteed to exist

Measuring velocity by differentiation of analog encoder signals

NARCIS (Netherlands)

Winarto, R.F.; Steinbuch, M.; Molengraft, van de M.J.G.

2013-01-01

In this report a new method for measuring velocities has been introduced. During the research in literature an overview has been made of the existing methods of measuring velocities. From this research, it can be concluded that a lot of existing approaches only work in specific settings. Besides

Description of a double centrifugation tube method for concentrating canine platelets.

Science.gov (United States)

Perazzi, Anna; Busetto, Roberto; Martinello, Tiziana; Drigo, Michele; Pasotto, Daniela; Cian, Francesco; Patruno, Marco; Iacopetti, Ilaria

2013-07-22

To evaluate the efficiency of platelet-rich plasma preparations by means of a double centrifugation tube method to obtain platelet-rich canine plasma at a concentration at least 4 times higher than the baseline value and a concentration of white blood cells not exceeding twice the reference range. A complete blood count was carried out for each sample and each concentrate. Whole blood samples were collected from 12 clinically healthy dogs (consenting blood donors). Blood was processed by a double centrifugation tube method to obtain platelet concentrates, which were then analyzed by a flow cytometry haematology system for haemogram. Platelet concentration and white blood cell count were determined in all samples. Platelet concentration at least 4 times higher than the baseline value and a white blood cell count not exceeding twice the reference range were obtained respectively in 10 cases out of 12 (83.3%) and 11 cases out of 12 (91.6%). This double centrifugation tube method is a relatively simple and inexpensive method for obtaining platelet-rich canine plasma, potentially available for therapeutic use to improve the healing process.

Analysis of the swimming velocity of cadmium-stressed Daphnia magna

International Nuclear Information System (INIS)

Baillieul, M.; Blust, R.

1999-01-01

The swimming velocity of the waterflea Daphnia magna is dependent on its body size. Therefore, environmental factors like toxic stress that influence growth also influence swimming velocity. An experiment was set up to test whether exposure to cadmium would reduce only growth, with a concomitant decrease in velocity, or whether it would reduce velocity below the swimming velocity of similarly-sized control animals. Daphnids were exposed for 10 days to free cadmium ion concentrations ranging from 1x10 -8 to 1x10 -7 M Cd 2+ , and body size and swimming velocity were measured every 2 days. The results showed that cadmium decreased both growth and velocity, i.e. exposed daphnids swam slower than similarly-sized control daphnids. Swimming velocity provided no indication of successful acclimation in any cadmium treatment. Food consumption and assimilation were reduced by exposure to cadmium. This reduced food intake may have, at least partially, caused the decreased growth rates. However, since reduced food intake does not affect swimming velocity, the reduced swimming velocity must be attributed to toxic effects of cadmium, other than those on food intake. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

An LES-PBE-PDF approach for modeling particle formation in turbulent reacting flows

Science.gov (United States)

Sewerin, Fabian; Rigopoulos, Stelios

2017-10-01

Many chemical and environmental processes involve the formation of a polydispersed particulate phase in a turbulent carrier flow. Frequently, the immersed particles are characterized by an intrinsic property such as the particle size, and the distribution of this property across a sample population is taken as an indicator for the quality of the particulate product or its environmental impact. In the present article, we propose a comprehensive model and an efficient numerical solution scheme for predicting the evolution of the property distribution associated with a polydispersed particulate phase forming in a turbulent reacting flow. Here, the particulate phase is described in terms of the particle number density whose evolution in both physical and particle property space is governed by the population balance equation (PBE). Based on the concept of large eddy simulation (LES), we augment the existing LES-transported probability density function (PDF) approach for fluid phase scalars by the particle number density and obtain a modeled evolution equation for the filtered PDF associated with the instantaneous fluid composition and particle property distribution. This LES-PBE-PDF approach allows us to predict the LES-filtered fluid composition and particle property distribution at each spatial location and point in time without any restriction on the chemical or particle formation kinetics. In view of a numerical solution, we apply the method of Eulerian stochastic fields, invoking an explicit adaptive grid technique in order to discretize the stochastic field equation for the number density in particle property space. In this way, sharp moving features of the particle property distribution can be accurately resolved at a significantly reduced computational cost. As a test case, we consider the condensation of an aerosol in a developed turbulent mixing layer. Our investigation not only demonstrates the predictive capabilities of the LES-PBE-PDF model but also

Comparative analysis of methods for concentrating venom from jellyfish Rhopilema esculentum Kishinouye

Science.gov (United States)

Li, Cuiping; Yu, Huahua; Feng, Jinhua; Chen, Xiaolin; Li, Pengcheng

2009-02-01

In this study, several methods were compared for the efficiency to concentrate venom from the tentacles of jellyfish Rhopilema esculentum Kishinouye. The results show that the methods using either freezing-dry or gel absorption to remove water to concentrate venom are not applicable due to the low concentration of the compounds dissolved. Although the recovery efficiency and the total venom obtained using the dialysis dehydration method are high, some proteins can be lost during the concentrating process. Comparing to the lyophilization method, ultrafiltration is a simple way to concentrate the compounds at high percentage but the hemolytic activities of the proteins obtained by ultrafiltration appear to be lower. Our results suggest that overall lyophilization is the best and recommended method to concentrate venom from the tentacles of jellyfish. It shows not only the high recovery efficiency for the venoms but high hemolytic activities as well.

Electron drift velocity measurements in liquid krypton-methane mixtures

CERN Document Server

Folegani, M; Magri, M; Piemontese, L

1999-01-01

Electron drift velocities have been measured in liquid krypton, pure and mixed with methane at different concentrations (1-10% in volume) versus electric field strength, and a possible effect of methane on electron lifetime has been investigated. While no effect on lifetime could be detected, since lifetimes were in all cases longer than what measurable, a very large increase in drift velocity (up to a factor 6) has been measured.

Analysis and forecasting of wind velocity in chetumal, quintana roo, using the single exponential smoothing method

Energy Technology Data Exchange (ETDEWEB)

Cadenas, E. [Facultad de Ingenieria Mecanica, Universidad Michoacana de San Nicolas de Hidalgo, Santiago Tapia No. 403, Centro (Mexico); Jaramillo, O.A.; Rivera, W. [Centro de Ivestigacion en Energia, Universidad Nacional Autonoma de Mexico, Apartado Postal 34, Temixco 62580, Morelos (Mexico)

2010-05-15

In this paper the analysis and forecasting of wind velocities in Chetumal, Quintana Roo, Mexico is presented. Measurements were made by the Instituto de Investigaciones Electricas (IIE) during two years, from 2004 to 2005. This location exemplifies the wind energy generation potential in the Caribbean coast of Mexico that could be employed in the hotel industry in the next decade. The wind speed and wind direction were measured at 10 m above ground level. Sensors with high accuracy and a low starting threshold were used. The wind velocity was recorded using a data acquisition system supplied by a 10 W photovoltaic panel. The wind speed values were measured with a frequency of 1 Hz and the average wind speed was recorded considering regular intervals of 10 min. First a statistical analysis of the time series was made in the first part of the paper through conventional and robust measures. Also the forecasting of the last day of measurements was made utilizing the single exponential smoothing method (SES). The results showed a very good accuracy of the data with this technique for an {alpha} value of 0.9. Finally the SES method was compared with the artificial neural network (ANN) method showing the former better results. (author)

Fulltext PDF

Indian Academy of Sciences (India)

user1

Self-Similar Solutions for Viscous and Resistive Advection Dominated Accretion. Flows (Kazem Faghei), 9. Photoionization Cross-Section of Chlorine-like Iron ... Photoelectric Radial Velocities, Paper XX: 45 Years' Monitoring of the Radial. Velocities of the Redman K Stars (R. F. Griffin & A. Stroe), 245. On the Maximum ...

Spectral analysis of surface waves method to assess shear wave velocity within centrifuge models

OpenAIRE

MURILLO, Carol Andrea; THOREL, Luc; CAICEDO, Bernardo

2009-01-01

The method of the spectral analysis of surface waves (SASW) is tested out on reduced scale centrifuge models, with a specific device, called the mini Falling Weight, developed for this purpose. Tests are performed on layered materials made of a mixture of sand and clay. The shear wave velocity VS determined within the models using the SASW is compared with the laboratory measurements carried out using the bender element test. The results show that the SASW technique applied to centrifuge test...

Waveform inversion of lateral velocity variation from wavefield source location perturbation

KAUST Repository

Choi, Yun Seok

2013-09-22

It is challenge in waveform inversion to precisely define the deep part of the velocity model compared to the shallow part. The lateral velocity variation, or what referred to as the derivative of velocity with respect to the horizontal distance, with well log data can be used to update the deep part of the velocity model more precisely. We develop a waveform inversion algorithm to obtain the lateral velocity variation by inverting the wavefield variation associated with the lateral shot location perturbation. The gradient of the new waveform inversion algorithm is obtained by the adjoint-state method. Our inversion algorithm focuses on resolving the lateral changes of the velocity model with respect to a fixed reference vertical velocity profile given by a well log. We apply the method on a simple-dome model to highlight the methods potential.

Heat transfer simulation of motorcycle fins under varying velocity using CFD method

Science.gov (United States)

Shahril, K.; Mohd Kasim, Nurhayati Binti; Sabri, M.

2013-12-01

Motorcycle engine releases heat to the atmosphere through the mode of force convection. To solve this, fins are provided on the outer of the cylinder. The heat transfer rate is defined depending on the velocity of vehicle, fin geometry and the ambient temperature. Increasing the temperature difference between the object and the environment, increasing the convection heat transfer coefficient, or increasing the surface area of the object increases the heat transfer. Many experimental methods are available in literature to analyze the effect of these factors on the heat transfer rate. However, CFD analysis will be use to simulate the heat transfer of the engine block. ANSYS software is selected to run the simulation.

Characterization of Medication Velocity and Size Distribution from Pressurized Metered-Dose Inhalers by Phase Doppler Anemometry.

Science.gov (United States)

Alatrash, Abubaker; Matida, Edgar

2016-12-01

Particle size and velocity are two of the most significant factors that impact the deposition of pressurized metered-dose inhaler (pMDI) sprays in the mouth cavity. pMDIs are prominently used around the world in the treatment of patients suffering from a variety of lung diseases such as asthma and chronic obstructive pulmonary disease. Since their introduction in the field, and as a result of their effectiveness and simplicity of usage, pMDIs are considered to be the most widely prescribed medical aerosol delivery system. In the current study, particle velocity and size distribution were measured at three different locations along the centerline of a pMDI spray using Phase Doppler Anemometry. pMDIs from four different pharmaceutical companies were tested, each using salbutamol sulfate as the medication. Measurements along at the pMDI centerline (at 0, 75, and 100 mm downstream of the inhaler mouthpiece) showed that the spray velocities were bimodal in time for all four pMDI brands. The first peak occurred as the spray was leaving the mouthpiece, while the second peak (at the same location, 0 mm) occurred at around 60, 95, 95, and 115 milliseconds later, respectively, for the four tested inhalers, with a drop in the velocity between the two peaks. Three probability density functions (PDFs) were tested, and the Rosin-Rammler PDF best fit the empirical data, as determined using a chi-squared test. These results suggest that there is a difference in the mean particle velocities at the centerline for the tested pMDIs and the diameter of released particles varied statistically for each brand.

Novel mining methods

CSIR Research Space (South Africa)

Monchusi, B

2012-10-01

Full Text Available stream_source_info Monchusi_2012.pdf.txt stream_content_type text/plain stream_size 1953 Content-Encoding ISO-8859-1 stream_name Monchusi_2012.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Novel Mining Methods 4th... 2012 Slide 12 CSIR mine safety platform AR Drone Differential time-of-flight beacon Sampling ? CSIR 2012 Slide 13 Reef Laser-Induced Breakdown Spectroscopy (LIBS) head Scan X-Y Laser/Spectrometer/Computer Rock Breaking ? CSIR 2012 Slide...

Spectral Velocity Estimation in the Transverse Direction

DEFF Research Database (Denmark)

Jensen, Jørgen Arendt

2013-01-01

A method for estimating the velocity spectrum for a fully transverse flow at a beam-to-flow angle of 90is described. The approach is based on the transverse oscillation (TO) method, where an oscillation across the ultrasound beam is made during receive processing. A fourth-order estimator based...... on the correlation of the received signal is derived. A Fourier transform of the correlation signal yields the velocity spectrum. Performing the estimation for short data segments gives the velocity spectrum as a function of time as for ordinary spectrograms, and it also works for a beam-to-flow angle of 90...... estimation scheme can reliably find the spectrum at 90, where a traditional estimator yields zero velocity. Measurements have been conducted with the SARUS experimental scanner and a BK 8820e convex array transducer (BK Medical, Herlev, Denmark). A CompuFlow 1000 (Shelley Automation, Inc, Toronto, Canada...

Quasiconvexity at the boundary and concentration effects generated by gradients

Czech Academy of Sciences Publication Activity Database

Kružík, Martin

2013-01-01

Roč. 19, č. 3 (2013), s. 679-700 ISSN 1292-8119 R&D Projects: GA ČR GAP201/10/0357; GA ČR(CZ) GAP201/12/0671 Institutional support: RVO:67985556 Keywords : bounded sequences of gradients * concentrations * oscillations Subject RIV: BA - General Mathematics Impact factor: 1.105, year: 2013 http://library.utia.cas.cz/separaty/2013/MTR/kruzik-0394748.pdf

Velocity measurement of conductor using electromagnetic induction

International Nuclear Information System (INIS)

Kim, Gu Hwa; Kim, Ho Young; Park, Joon Po; Jeong, Hee Tae; Lee, Eui Wan

2002-01-01

A basic technology was investigated to measure the speed of conductor by non-contact electromagnetic method. The principle of the velocity sensor was electromagnetic induction. To design electromagnet for velocity sensor, 2D electromagnetic analysis was performed using FEM software. The sensor output was analyzed according to the parameters of velocity sensor, such as the type of magnetizing currents and the lift-off. Output of magnetic sensor was linearly depended on the conductor speed and magnetizing current. To compensate the lift-off changes during measurement of velocity, the other magnetic sensor was put at the pole of electromagnet.

Density, ultrasound velocity, acoustic impedance, reflection and absorption coefficient determination of liquids via multiple reflection method.

Science.gov (United States)

Hoche, S; Hussein, M A; Becker, T

2015-03-01

The accuracy of density, reflection coefficient, and acoustic impedance determination via multiple reflection method was validated experimentally. The ternary system water-maltose-ethanol was used to execute a systematic, temperature dependent study over a wide range of densities and viscosities aiming an application as inline sensor in beverage industries. The validation results of the presented method and setup show root mean square errors of: 1.201E-3 g cm(-3) (±0.12%) density, 0.515E-3 (0.15%) reflection coefficient and 1.851E+3 kg s(-1) m(-2) (0.12%) specific acoustic impedance. The results of the diffraction corrected absorption showed an average standard deviation of only 0.12%. It was found that the absorption change shows a good correlation to concentration variations and may be useful for laboratory analysis of sufficiently pure liquids. The main part of the observed errors can be explained by the observed noise, temperature variation and the low signal resolution of 50 MHz. In particular, the poor signal-to-noise ratio of the second reflector echo was found to be a main accuracy limitation. Concerning the investigation of liquids the unstable properties of the reference material PMMA, due to hygroscopicity, were identified to be an additional, unpredictable source of uncertainty. While dimensional changes can be considered by adequate methodology, the impact of the time and temperature dependent water absorption on relevant reference properties like the buffer's sound velocity and density could not be considered and may explain part of the observed deviations. Copyright © 2014 Elsevier B.V. All rights reserved.

A new settling velocity model to describe secondary sedimentation.

Science.gov (United States)

Ramin, Elham; Wágner, Dorottya S; Yde, Lars; Binning, Philip J; Rasmussen, Michael R; Mikkelsen, Peter Steen; Plósz, Benedek Gy

2014-12-01

Secondary settling tanks (SSTs) are the most hydraulically sensitive unit operations in biological wastewater treatment plants. The maximum permissible inflow to the plant depends on the efficiency of SSTs in separating and thickening the activated sludge. The flow conditions and solids distribution in SSTs can be predicted using computational fluid dynamics (CFD) tools. Despite extensive studies on the compression settling behaviour of activated sludge and the development of advanced settling velocity models for use in SST simulations, these models are not often used, due to the challenges associated with their calibration. In this study, we developed a new settling velocity model, including hindered, transient and compression settling, and showed that it can be calibrated to data from a simple, novel settling column experimental set-up using the Bayesian optimization method DREAM(ZS). In addition, correlations between the Herschel-Bulkley rheological model parameters and sludge concentration were identified with data from batch rheological experiments. A 2-D axisymmetric CFD model of a circular SST containing the new settling velocity and rheological model was validated with full-scale measurements. Finally, it was shown that the representation of compression settling in the CFD model can significantly influence the prediction of sludge distribution in the SSTs under dry- and wet-weather flow conditions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Circular mode: a new scanning probe microscopy method for investigating surface properties at constant and continuous scanning velocities.

Science.gov (United States)

Nasrallah, Hussein; Mazeran, Pierre-Emmanuel; Noël, Olivier

2011-11-01

In this paper, we introduce a novel scanning probe microscopy mode, called the circular mode, which offers expanded capabilities for surface investigations especially for measuring physical properties that require high scanning velocities and/or continuous displacement with no rest periods. To achieve these specific conditions, we have implemented a circular horizontal displacement of the probe relative to the sample plane. Thus the relative probe displacement follows a circular path rather than the conventional back and forth linear one. The circular mode offers advantages such as high and constant scanning velocities, the possibility to be combined with other classical operating modes, and a simpler calibration method of the actuators generating the relative displacement. As application examples of this mode, we report its ability to (1) investigate the influence of scanning velocity on adhesion forces, (2) measure easily and instantly the friction coefficient, and (3) generate wear tracks very rapidly for tribological investigations. © 2011 American Institute of Physics

One-loop fluctuation-dissipation formula for bubble-wall velocity

International Nuclear Information System (INIS)

Arnold, P.

1993-01-01

The limiting bubble wall velocity during a first-order electroweak phase transition is of interest in scenarios for electroweak baryogenesis. Khlebnikov has recently proposed an interesting method for computing this velocity based on the fluctuation-dissipation theorem. It is demonstrated that at one-loop order this method is identical to simple, earlier techniques for computing the wall velocity based on computing the friction from particles reflecting off or transmitting through the wall in the ideal gas limit

One-loop fluctuation-dissipation formula for bubble-wall velocity

International Nuclear Information System (INIS)

Arnold, P.

1993-01-01

The limiting bubble-wall velocity during a first-order electroweak phase transition is of interest in scenarios for electroweak baryogenesis. Khlebnikov has recently proposed an interesting method for computing this velocity based on the fluctuation-dissipation theorem. I demonstrate that at one-loop order this method is identical to simple, earlier techniques for computing the wall velocity based on computing the friction from particles reflecting off or transmitting through the wall in the ideal gas (''thin-wall'') limit

The impact of the photon PDF and electroweak corrections on t anti t distributions

International Nuclear Information System (INIS)

Pagani, D.; Tsinikos, I.; Zaro, M.

2016-01-01

We discuss the impact of EW corrections on differential distributions in top-quark pair production at the LHC and future hadron colliders, focussing on the effects of initial-state photons. Performing a calculation at Next-to-Leading Order QCD+EW accuracy, we investigate in detail the impact of photon-initiated channels on central values as well as PDF and scale uncertainties, both at order α s α and α s 2 α. We present predictions at 13 and 100 TeV, and provide results for the 8 TeV differential measurements performed by ATLAS and CMS. A thorough comparison of results obtained with the NNPDF2.3QED and CT14QED PDF sets is performed. While contributions due to the photon PDF are negligible with CT14QED, this is not the case for NNPDF2.3QED, where such contributions are sizeable and show large PDF uncertainties. On the one hand, we show that differential observables in top-pair production, in particular top-quark and t anti t rapidities, can be used to improve the determination of the photon PDF within the NNPDF approach. On the other hand, with current PDF sets, we demonstrate the necessity of including EW corrections and photon-induced contributions for a correct determination of both the central value and the uncertainties of theoretical predictions. (orig.)

The impact of the photon PDF and electroweak corrections on t anti t distributions

Energy Technology Data Exchange (ETDEWEB)

Pagani, D.; Tsinikos, I. [Universite Catholique de Louvain, Centre for Cosmology, Particle Physics and Phenomenology (CP3), Louvain-la-Neuve (Belgium); Zaro, M. [Sorbonne Universites, UPMC University Paris 06, UMR 589, LPTHE, Paris (France); CNRS, UMR 7589, LPTHE, Paris (France)

2016-09-15

We discuss the impact of EW corrections on differential distributions in top-quark pair production at the LHC and future hadron colliders, focussing on the effects of initial-state photons. Performing a calculation at Next-to-Leading Order QCD+EW accuracy, we investigate in detail the impact of photon-initiated channels on central values as well as PDF and scale uncertainties, both at order α{sub s}α and α{sub s}{sup 2}α. We present predictions at 13 and 100 TeV, and provide results for the 8 TeV differential measurements performed by ATLAS and CMS. A thorough comparison of results obtained with the NNPDF2.3QED and CT14QED PDF sets is performed. While contributions due to the photon PDF are negligible with CT14QED, this is not the case for NNPDF2.3QED, where such contributions are sizeable and show large PDF uncertainties. On the one hand, we show that differential observables in top-pair production, in particular top-quark and t anti t rapidities, can be used to improve the determination of the photon PDF within the NNPDF approach. On the other hand, with current PDF sets, we demonstrate the necessity of including EW corrections and photon-induced contributions for a correct determination of both the central value and the uncertainties of theoretical predictions. (orig.)

Evaluation of single and double centrifugation tube methods for concentrating equine platelets.

Science.gov (United States)

Argüelles, D; Carmona, J U; Pastor, J; Iborra, A; Viñals, L; Martínez, P; Bach, E; Prades, M

2006-10-01

The aim of this study was to evaluate single and double centrifugation tube methods for concentrating equine platelets. Whole blood samples were collected from clinically normal horses and processed by use of single and double centrifugation tube methods to obtain four platelet concentrates (PCs): PC-A, PC-B, PC-C, and PC-D, which were analyzed using a flow cytometry hematology system for hemogram and additional platelet parameters (mean platelet volume, platelet distribution width, mean platelet component concentration, mean platelet component distribution width). Concentrations of transforming growth factor beta 1 (TGF-beta(1)) were determined in all the samples. Platelet concentrations for PC-A, PC-B, PC-C, and PC-D were 45%, 44%, 71%, and 21% higher, respectively, compared to the same values for citrated whole blood samples. TGF-beta(1) concentrations for PC-A, PC-B, PC-C, and PC-D were 38%, 44%, 44%, and 37% higher, respectively, compared to citrated whole blood sample values. In conclusion, the single and double centrifugation tube methods are reliable methods for concentrating equine platelets and for obtaining potentially therapeutic TGF-beta(1) levels.

Aerosol deposition velocities on the Pacific and Atlantic oceans calculated from 7Be measurements

International Nuclear Information System (INIS)

Young, J.A.; Silker, W.B.

1979-01-01

The concentrations of 7 Be were measured in Pacific and Atlantic ocean water for past several years to determine the deposition velocity of aerosol particles on the ocean surface. Beryllium-7 is produced at a relatively constant rate in the atmosphere by spallation reactions of cosmic rays with atmospheric nitrogen and oxygen. Immediately after its formation 7 Be becomes attached to aerosol particles, and therefore can serve as tracers of the subsequent behavior of these particles. Isopleths of 7 Be surface water concentration, 7 Be inventory in the ocean, and deposition velocity have been prepared for the Pacific Ocean from 30 0 S to 60 0 N and for the Atlantic Ocean from 10 0 N to 55 0 N. The concentrations, inventories and deposition velocities tended to be higher in regions where precipitation was high, and generally increased with latitude. The average flux of 7 Be across the ocean surface was calculated to be 0.027 atoms cm -2 sec -1 which is probably not significantly greater than the worldwide average 7 Be flux across land and ocean surfaces of 0.022 atoms cm -2 sec -1 calculated by Lal and Peters. The average deposition velocity was calculated to be 0.80 cm sec -1 . This value may be 10 to 30% too low, since it was calculated using atmospheric 7 Be concentrations which were measured at continental stations. Measurements of atmospheric 7 Be concentrations at ocean stations suggest that the concentrations at the continental stations averaged 10 to 30% higher than the concentrations over the ocean

Aerosol deposition velocities on the Pacific and Atlantic oceans calculated from 7Be measurements

International Nuclear Information System (INIS)

Young, J.A.; Silker, W.B.

1980-01-01

The concentrations of 7 Be have been measured in Pacific and Atlantic ocean water for the past several years to determine the deposition velocity of aerosol particles on the ocean surface. 7 Be is produced at a relatively constant rate in the atmosphere by spallation reactions of cosmic rays with atmospheric nitrogen and oxygen. Immediately after its formation 7 Be becomes attached to aerosol particles, and therefore can serve as tracers of the subsequent behavior of these particles. Isopleths of 7 Be surface water concentrations, 7 Be inventory in the ocean, and deposition velocity have been prepared for the Pacific Ocean from 30 0 S to 60 0 N and for the Atlantic Ocean from 10 0 N to 55 0 N. The concentrations, inventories and deposition velocities tended to be higher in regions where precipitation was high, and generally increased with latitude. The average flux of 7 Be across the ocean surface was calculated to be 0.027 atoms cm -2 s -1 which is probably not significantly greater than the worldwide average 7 Be flux across land and ocean surfaces of 0.022 atoms cm -2 s -1 calculated by Lal and Peters. The average deposition velocity was calculated to be 0.80 cm s -1 . This value may be 10-50% too low, since it was calculated using atmospheric 7 Be concentrations which were measured at continental stations. Measurements of atmospheric 7 Be concentrations at ocean stations suggest that the concentrations at the continental stations averaged 10-50% higher than the concentrations over the ocean. (orig.)

Large-scale structure of the Taurus molecular complex. II. Analysis of velocity fluctuations and turbulence. III. Methods for turbulence

International Nuclear Information System (INIS)

Kleiner, S.C.; Dickman, R.L.

1985-01-01

The velocity autocorrelation function (ACF) of observed spectral line centroid fluctuations is noted to effectively reproduce the actual ACF of turbulent gas motions within an interstellar cloud, thereby furnishing a framework for the study of the large scale velocity structure of the Taurus dark cloud complex traced by the present C-13O J = 1-0 observations of this region. The results obtained are discussed in the context of recent suggestions that widely observed correlations between molecular cloud widths and cloud sizes indicate the presence of a continuum of turbulent motions within the dense interstellar medium. Attention is then given to a method for the quantitative study of these turbulent motions, involving the mapping of a source in an optically thin spectral line and studying the spatial correlation properties of the resulting velocity centroid map. 61 references

Clearance rate of Mytilus edulis (L.) as a function of current velocity and mussel aggregation

DEFF Research Database (Denmark)

Nielsen, Pernille; Vismann, Bent

2014-01-01

by current velocities up to 1.4 m/sec, whereas experiments with 3 mussels showed that clearance of the mussels decreased progressively at current velocities greater than 0.2 m/sec, and reached 0 L/h per individual at current velocities greater than 0.6 m/sec. The constant feeding at all current velocities......The aim of the current study was to investigate the effect of water current velocities on the clearance rate of Mytilus edulis when different numbers of mussels were used in the experiments. An automatic setup, which controlled and monitored the algal concentration continually, was used to measure...... the effect of increasing current velocity (0.05-1.4 m/sec) on the M. edulis clearance rate. Clearance rate measurements were performed under constant food concentrations of 3,000 cells/mL of Rhodomonas salina on either 3 mussels or 20 mussels. We found that the clearance rate of 20 mussels was unaffected...

Determination of hydrogen cluster velocities and comparison with numerical calculations

International Nuclear Information System (INIS)

Täschner, A.; Köhler, E.; Ortjohann, H.-W.; Khoukaz, A.

2013-01-01

The use of powerful hydrogen cluster jet targets in storage ring experiments led to the need of precise data on the mean cluster velocity as function of the stagnation temperature and pressure for the determination of the volume density of the target beams. For this purpose a large data set of hydrogen cluster velocity distributions and mean velocities was measured at a high density hydrogen cluster jet target using a trumpet shaped nozzle. The measurements have been performed at pressures above and below the critical pressure and for a broad range of temperatures relevant for target operation, e.g., at storage ring experiments. The used experimental method is described which allows for the velocity measurement of single clusters using a time-of-flight technique. Since this method is rather time-consuming and these measurements are typically interfering negatively with storage ring experiments, a method for a precise calculation of these mean velocities was needed. For this, the determined mean cluster velocities are compared with model calculations based on an isentropic one-dimensional van der Waals gas. Based on the obtained data and the presented numerical calculations, a new method has been developed which allows to predict the mean cluster velocities with an accuracy of about 5%. For this two cut-off parameters defining positions inside the nozzle are introduced, which can be determined for a given nozzle by only two velocity measurements

High-pressure pair distribution function (PDF) measurement using high-energy focused x-ray beam

Energy Technology Data Exchange (ETDEWEB)

Hong, Xinguo, E-mail: xhong@bnl.gov; Weidner, Donald J. [Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794 (United States); Ehm, Lars [Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794 (United States); National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973 (United States); Zhong, Zhong; Ghose, Sanjit [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, NY 11973 (United States); Duffy, Thomas S. [Department of Geosciences, Princeton University, Princeton, NJ 08544 (United States)

2016-07-27

In this paper, we report recent development of the high-pressure pair distribution function (HP-PDF) measurement technique using a focused high-energy X-ray beam coupled with a diamond anvil cell (DAC). The focusing optics consist of a sagittally bent Laue monochromator and Kirkpatrick-Baez (K–B) mirrors. This combination provides a clean high-energy X-ray beam suitable for HP-PDF research. Demonstration of the HP-PDF technique for nanocrystalline platinum under quasi-hydrostatic condition above 30 GPa is presented.

Fulltext PDF

Indian Academy of Sciences (India)

a certain velocity, the brake is then applied, the resistive force being 12 per unit mass. The train comes to rest at station B. Assume that the air resistance experienced by the train during motion is proportional to its velocity, the proportionality constant being k. If T is the time of travel between A and B, express the distance ...

Fulltext PDF

Indian Academy of Sciences (India)

ing a certain velocity, the brake is then applied, the resistive force being 12 per unit mass. The train comes to rest at station B. Assume that the air resistance experienced by the train during motion is proportional to its velocity, the proportionality constant being k. If T is the time of travel between A and B, express the distance ...

Comparison of three different methods for assessing in situ friction velocity: A case study from Loch Etive, Scotland

DEFF Research Database (Denmark)

Inoue, Tetsunori; Glud, Ronnie N.; Stahl, Henrik

2011-01-01

Three approaches, Eddy Correlation (EC), Turbulent Kinetic Energy (TKE), and Inertial Dissipation (ID) methods, were compared to evaluate their potential for estimation of friction velocity in a Scottish sea loch. As an independent assessment parameter, we used simultaneous O2 recordings of the d...

Acute influence of the application of strength treatment based on the combinated contrast training method on precision and velocity in overarm handball throwing

Directory of Open Access Journals (Sweden)

Juan S. Gómez Navarrete

2011-01-01

Full Text Available Abstract Combination of strengh training methods has been shown as an effective way for strengh development. This is specially indicated for improving explosive strengh and power. Our study shows the influence of combined contrast improvement method on overarm throwing in handball. Treatment consisted on one session of combined contras method. 10 handball palyers and 13 non-players participated in this estudy. The instrumental was a gun radar to know velocity throws, a camera to digitalize the accuracy, and an isometric dynamometer for strenght data collection. Results show a significant decrease in peak of force values in players group. Another significant decrease was obsesrved on integral to peak force for both groups. There are significant positive relations between throwing velocity parameters related to weight and size with isometric peak of force. We concluded that isometric time/strengh curve is an usefull instrument to observe changes produced in the subjet's capacity of producing strengh during training. Keywords: Precision, velocity, overarm handball throwing, isometric test, combined contrast method

Optical efficiency of solar concentrators by a reverse optical path method.

Science.gov (United States)

Parretta, A; Antonini, A; Milan, E; Stefancich, M; Martinelli, G; Armani, M

2008-09-15

A method for the optical characterization of a solar concentrator, based on the reverse illumination by a Lambertian source and measurement of intensity of light projected on a far screen, has been developed. It is shown that the projected light intensity is simply correlated to the angle-resolved efficiency of a concentrator, conventionally obtained by a direct illumination procedure. The method has been applied by simulating simple reflective nonimaging and Fresnel lens concentrators.

Reference and PDF-manager software: complexities, support and workflow.

Science.gov (United States)

Mead, Thomas L; Berryman, Donna R

2010-10-01

In the past, librarians taught reference management by training library users to use established software programs such as RefWorks or EndNote. In today's environment, there is a proliferation of Web-based programs that are being used by library clientele that offer a new twist on the well-known reference management programs. Basically, these new programs are PDF-manager software (e.g., Mendeley or Papers). Librarians are faced with new questions, issues, and concerns, given the new workflows and pathways that these PDF-manager programs present. This article takes a look at some of those.

Examples of invasive and non-invasive methods for estimation of shear-wave velocity profile in Bucharest

International Nuclear Information System (INIS)

Aldea, A.; Albota, E.; Yamanaka, H.; Fukumoto, S.; Poiata, N.

2007-01-01

The estimation of subsurface shear-wave velocity is of major importance for understanding and modelling site-response and surface ground motion. The shear-wave velocity profile strongly influence the shear-wave part of the seismic motion that proved to be the most damaging one. The improvement of input seismic ground motion for design is one of the long-term objectives within the Japan International Cooperation Agency (JICA) Project in Romania. Two approaches were used: installation of a digital seismic network and soil investigations (in situ and in laboratory). National Center for Seismic Risk Reduction (NCSRR, Romania), the implementing agency of JICA Project, performed these activities in cooperation with Japanese partner institutions, and an efficient know-how transfer was achieved. Between the soil investigation activities, a special importance was given to the estimation of shear-wave velocity profile. The present paper presents results from PS logging tests at NCSRR seismic station sites, and from single-station and array microtremor measurements. Other results from PS logging tests, surface-wave method and in situ and laboratory geotechnical investigations are presented in other papers in these proceedings. In future, a joint-collaborative effort of Romanian institutions may allow an improved characterisation of the soil profile beneath Bucharest. (authors)

Evaluation of granite weathering in the Jeroným Mine using non-destructive methods

Czech Academy of Sciences Publication Activity Database

Lednická, Markéta; Kaláb, Zdeněk

2012-01-01

Roč. 9, č. 2 (2012), s. 211-220 ISSN 1214-9705 R&D Projects: GA ČR GA105/09/0089 Institutional support: RVO:68145535 Keywords : weathering * granite, mine * ultrasonic pulse velocity * Schmidt hammer Subject RIV: DH - Mining, incl. Coal Mining Impact factor: 0.530, year: 2011 http://www.irsm.cas.cz/abstracts/AGG/02_12/10_Lednicka_Kalab.pdf

Comparison of four methods to assess colostral IgG concentration in dairy cows.

Science.gov (United States)

Chigerwe, Munashe; Tyler, Jeff W; Middleton, John R; Spain, James N; Dill, Jeffrey S; Steevens, Barry J

2008-09-01

To determine sensitivity and specificity of 4 methods to assess colostral IgG concentration in dairy cows and determine the optimal cutpoint for each method. Cross-sectional study. 160 Holstein dairy cows. 171 composite colostrum samples collected within 2 hours after parturition were used in the study. Test methods used to estimate colostral IgG concentration consisted of weight of the first milking, 2 hydrometers, and an electronic refractometer. Results of the test methods were compared with colostral IgG concentration determined by means of radial immunodiffusion. For each method, sensitivity and specificity for detecting colostral IgG concentration hydrometer 1, 0.75; hydrometer 2, 0.76; refractometer, 0.75), but no significant differences were identified among the other 3 methods with regard to sensitivity. Specificities at the optimal cutpoint were similar for all 4 methods. Results suggested that use of either hydrometer or the electronic refractometer was an acceptable method of screening colostrum for low IgG concentration; however, the manufacturer-defined scale for both hydrometers overestimated colostral IgG concentration. Use of weight of the first milking as a screening test to identify bovine colostrum with inadequate IgG concentration could not be justified because of the low sensitivity.

An Investigation of a Hybrid Mixing Model for PDF Simulations of Turbulent Premixed Flames

Science.gov (United States)

Zhou, Hua; Li, Shan; Wang, Hu; Ren, Zhuyin

2015-11-01

Predictive simulations of turbulent premixed flames over a wide range of Damköhler numbers in the framework of Probability Density Function (PDF) method still remain challenging due to the deficiency in current micro-mixing models. In this work, a hybrid micro-mixing model, valid in both the flamelet regime and broken reaction zone regime, is proposed. A priori testing of this model is first performed by examining the conditional scalar dissipation rate and conditional scalar diffusion in a 3-D direct numerical simulation dataset of a temporally evolving turbulent slot jet flame of lean premixed H2-air in the thin reaction zone regime. Then, this new model is applied to PDF simulations of the Piloted Premixed Jet Burner (PPJB) flames, which are a set of highly shear turbulent premixed flames and feature strong turbulence-chemistry interaction at high Reynolds and Karlovitz numbers. Supported by NSFC 51476087 and NSFC 91441202.

Velocity spectrum for the Iranian plateau

Science.gov (United States)

Bastami, Morteza; Soghrat, M. R.

2018-01-01

Peak ground acceleration (PGA) and spectral acceleration values have been proposed in most building codes/guidelines, unlike spectral velocity (SV) and peak ground velocity (PGV). Recent studies have demonstrated the importance of spectral velocity and peak ground velocity in the design of long period structures (e.g., pipelines, tunnels, tanks, and high-rise buildings) and evaluation of seismic vulnerability in underground structures. The current study was undertaken to develop a velocity spectrum and for estimation of PGV. In order to determine these parameters, 398 three-component accelerograms recorded by the Building and Housing Research Center (BHRC) were used. The moment magnitude (Mw) in the selected database was 4.1 to 7.3, and the events occurred after 1977. In the database, the average shear-wave velocity at 0 to 30 m in depth (Vs30) was available for only 217 records; thus, the site class for the remaining was estimated using empirical methods. Because of the importance of the velocity spectrum at low frequencies, the signal-to-noise ratio of 2 was chosen for determination of the low and high frequency to include a wider range of frequency content. This value can produce conservative results. After estimation of the shape of the velocity design spectrum, the PGV was also estimated for the region under study by finding the correlation between PGV and spectral acceleration at the period of 1 s.

Conduction velocity of antigravity muscle action potentials.

Science.gov (United States)

Christova, L; Kosarov, D; Christova, P

1992-01-01

The conduction velocity of the impulses along the muscle fibers is one of the parameters of the extraterritorial potentials of the motor units allowing for the evaluation of the functional state of the muscles. There are no data about the conduction velocities of antigravity muscleaction potentials. In this paper we offer a method for measuring conduction velocity of potentials of single MUs and the averaged potentials of the interference electromiogram (IEMG) lead-off by surface electrodes from mm. sternocleidomastoideus, trapezius, deltoideus (caput laterale) and vastus medialis. The measured mean values of the conduction velocity of antigravity muscles potentials can be used for testing the functional state of the muscles.

An Automatic High Efficient Method for Dish Concentrator Alignment

Directory of Open Access Journals (Sweden)

Yong Wang

2014-01-01

for the alignment of faceted solar dish concentrator. The isosceles triangle configuration of facet’s footholds determines a fixed relation between light spot displacements and foothold movements, which allows an automatic determination of the amount of adjustments. Tests on a 25 kW Stirling Energy System dish concentrator verify the feasibility, accuracy, and efficiency of our method.

Magnetic flux concentration methods for magnetic energy harvesting module

Directory of Open Access Journals (Sweden)

Wakiwaka Hiroyuki

2013-01-01

Full Text Available This paper presents magnetic flux concentration methods for magnetic energy harvesting module. The purpose of this study is to harvest 1 mW energy with a Brooks coil 2 cm in diameter from environmental magnetic field at 60 Hz. Because the harvesting power is proportional to the square of the magnetic flux density, we consider the use of a magnetic flux concentration coil and a magnetic core. The magnetic flux concentration coil consists of an air­core Brooks coil and a resonant capacitor. When a uniform magnetic field crossed the coil, the magnetic flux distribution around the coil was changed. It is found that the magnetic field in an area is concentrated larger than 20 times compared with the uniform magnetic field. Compared with the air­core coil, our designed magnetic core makes the harvested energy ten­fold. According to ICNIRP2010 guideline, the acceptable level of magnetic field is 0.2 mT in the frequency range between 25 Hz and 400 Hz. Without the two magnetic flux concentration methods, the corresponding energy is limited to 1 µW. In contrast, our experimental results successfully demonstrate energy harvesting of 1 mW from a magnetic field of 0.03 mT at 60 Hz.

Reliability of the Load-Velocity Relationship Obtained Through Linear and Polynomial Regression Models to Predict the One-Repetition Maximum Load.

Science.gov (United States)

Pestaña-Melero, Francisco Luis; Haff, G Gregory; Rojas, Francisco Javier; Pérez-Castilla, Alejandro; García-Ramos, Amador

2017-12-18

This study aimed to compare the between-session reliability of the load-velocity relationship between (1) linear vs. polynomial regression models, (2) concentric-only vs. eccentric-concentric bench press variants, as well as (3) the within-participants vs. the between-participants variability of the velocity attained at each percentage of the one-repetition maximum (%1RM). The load-velocity relationship of 30 men (age: 21.2±3.8 y; height: 1.78±0.07 m, body mass: 72.3±7.3 kg; bench press 1RM: 78.8±13.2 kg) were evaluated by means of linear and polynomial regression models in the concentric-only and eccentric-concentric bench press variants in a Smith Machine. Two sessions were performed with each bench press variant. The main findings were: (1) first-order-polynomials (CV: 4.39%-4.70%) provided the load-velocity relationship with higher reliability than second-order-polynomials (CV: 4.68%-5.04%); (2) the reliability of the load-velocity relationship did not differ between the concentric-only and eccentric-concentric bench press variants; (3) the within-participants variability of the velocity attained at each %1RM was markedly lower than the between-participants variability. Taken together, these results highlight that, regardless of the bench press variant considered, the individual determination of the load-velocity relationship by a linear regression model could be recommended to monitor and prescribe the relative load in the Smith machine bench press exercise.

Computational analysis for velocity slip and diffusion species with carbon nanotubes

Directory of Open Access Journals (Sweden)

T. Hayat

Full Text Available This article addresses a computational study for carbon nanotubes with diffusion species. Mathematical analysis and modeling are formulated in the presence of slip effect, Darcy porous medium and chemical species. Diffusion coefficients are accounted as equal amount. Optimal Homotopy Analysis Method (OHAM is implemented in taking care for convergence control parameters. Residual errors and its graphs are plotted for CNTs nanofluids. The current data is compared with the previous published work. The results are found in favorable agreement. Physically interesting parameters are highlighted. The velocity is dominated for MWCNT than SWCNT. The velocity profile increases for power index when m>1 while opposite trend is observed for power index when m<1. Permeability parameter and volume fraction reduce the skin friction coefficient and reverse trend is noticed for slip parameter and wall thickness parameter. Opposite behavior is noticed for concentration profile at surface for homogenous-heterogeneous reactions parameters. Keywords: Chemical species, Carbon nanotubes, Nonuniform stretching sheet, Slip effects

Measurements of the laminar burning velocity of hydrogen-air premixed flames

Energy Technology Data Exchange (ETDEWEB)

Pareja, Jhon; Burbano, Hugo J. [Science and Technology of Gases and Rational Use of Energy Group, Faculty of Engineering, University of Antioquia, Calle 67 N 53, 108 Bloque 20, 447 Medellin (Colombia); Ogami, Yasuhiro [Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan)

2010-02-15

Experimental and numerical studies on laminar burning velocities of hydrogen-air mixtures were performed at standard pressure and room temperature varying the equivalence ratio from 0.8 to 3.0. The flames were generated using a contoured slot-type nozzle burner (4 mm x 10 mm). Measurements of laminar burning velocity were conducted using particle tracking velocimetry (PTV) combined with Schlieren photography. This technique provides the information of instantaneous local burning velocities in the whole region of the flame front, and laminar burning velocities were determined using the mean value of local burning velocities in the region of non-stretch. Additionally, average laminar burning velocities were determined using the angle method and compared with the data obtained with the PTV method. Numerical calculations were also conducted using detailed reaction mechanisms and transport properties. The experimental results from the PTV method are in good agreement with the numerical results at every equivalence ratio of the range of study. Differences between the results obtained with the angle method and those with the PTV method are reasonably small when the effects of flame stretch and curvature are reduced by using a contoured slot-type nozzle. (author)

Time-dependent coolant velocity measurements in an operating BWR

International Nuclear Information System (INIS)

Luebbesmeyer, D.; Crowe, R.D.

1980-01-01

A method to measure time-dependent fluid velocities in BWR-bundle elements by noise analysis of the incore-neutron-detector signals is shown. Two application examples of the new method are given. The time behaviour of the fluid velocity in the bundle element during a scheduled power excursion of the plant. The change of power was performed by changing the coolant flow through the core The apparent change of the fluid velocity due to thermal elongation of the helix-drive of the TIP-system. A simplified mathematical model was derived for this elongation to use as a reference to check the validity of the new method. (author)

Collaborative validation of a rapid method for efficient virus concentration in bottled water

DEFF Research Database (Denmark)

Schultz, Anna Charlotte; Perelle, Sylvie; Di Pasquale, Simona

2011-01-01

. Three newly developed methods, A, B and C, for virus concentration in bottled water were compared against the reference method D: (A) Convective Interaction Media (CIM) monolithic chromatography; filtration of viruses followed by (B) direct lysis of viruses on membrane; (C) concentration of viruses......Enteric viruses, including norovirus (NoV) and hepatitis A virus (HAV), have emerged as a major cause of waterborne outbreaks worldwide. Due to their low infectious doses and low concentrations in water samples, an efficient and rapid virus concentration method is required for routine control...... by ultracentrifugation; and (D) concentration of viruses by ultrafiltration, for each methods' (A, B and C) efficacy to recover 10-fold dilutions of HAV and feline calicivirus (FCV) spiked in bottles of 1.5L of mineral water. Within the tested characteristics, all the new methods showed better performance than method D...

Global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity

Science.gov (United States)

Chounet, Agnès; Vallée, Martin; Causse, Mathieu; Courboulex, Françoise

2018-05-01

Application of the SCARDEC method provides the apparent source time functions together with seismic moment, depth, and focal mechanism, for most of the recent earthquakes with magnitude larger than 5.6-6. Using this large dataset, we have developed a method to systematically invert for the rupture direction and average rupture velocity Vr, when unilateral rupture propagation dominates. The approach is applied to all the shallow (z earthquakes of the catalog over the 1992-2015 time period. After a careful validation process, rupture properties for a catalog of 96 earthquakes are obtained. The subsequent analysis of this catalog provides several insights about the seismic rupture process. We first report that up-dip ruptures are more abundant than down-dip ruptures for shallow subduction interface earthquakes, which can be understood as a consequence of the material contrast between the slab and the overriding crust. Rupture velocities, which are searched without any a-priori up to the maximal P wave velocity (6000-8000 m/s), are found between 1200 m/s and 4500 m/s. This observation indicates that no earthquakes propagate over long distances with rupture velocity approaching the P wave velocity. Among the 23 ruptures faster than 3100 m/s, we observe both documented supershear ruptures (e.g. the 2001 Kunlun earthquake), and undocumented ruptures that very likely include a supershear phase. We also find that the correlation of Vr with the source duration scaled to the seismic moment (Ts) is very weak. This directly implies that both Ts and Vr are anticorrelated with the stress drop Δσ. This result has implications for the assessment of the peak ground acceleration (PGA) variability. As shown by Causse and Song (2015), an anticorrelation between Δσ and Vr significantly reduces the predicted PGA variability, and brings it closer to the observed variability.

3D Vector Velocity Estimation using a 2D Phased Array

DEFF Research Database (Denmark)

Pihl, Michael Johannes; Jensen, Jørgen Arendt

2011-01-01

of using the TO method for estimation 3D velocity vectors, and the proposed decoupling is demonstrated. A 64x64 and a 32x32 elements transducer are emulated using Field II. Plug flow with a speed of 1 m/s in a small region is rotated in the XY -plane. A binary flow example with [vx,vy]=[1,0] and [0,1] m......A method to estimate the three dimensional (3D) velocity vector is presented is this paper. 3D velocity vector techniques are needed to measure the full velocity and characterize the complicated flow patterns in the human body. The Transverse Oscillation (TO) method introduces oscillations...... matrix transducer. For the 32x32 transducer, the mean and standard deviation for the speed are 0.94 0.11 m/s and for the angle bias -0.487.7. The simulation study clearly demonstrates, that the new method can be used to estimate the 3D velocity vector using a 2D phased matrix array, and that the velocity...