Pairing-induced kinetic energy lowering in doped antiferromagnets
NASA Astrophysics Data System (ADS)
Wróbel, P.; Eder, R.; Fulde, P.
2003-10-01
We analyse lowering of the kinetic energy in doped antiferromagnets at the transition to the superconducting state. Measurements of optical conductivity indicate that such unconventional behaviour takes place in underdoped Bi-2212. We argue that the definition of the operator representing the kinetic energy is determined by experimental conditions. The thermodynamic average of that operator is related to the integrated spectral weight of the optical conductivity and thus depends on the cut-off frequency limiting that integral. If the upper limit of the integral lies below the charge transfer gap the spectral weight represents the average of the hopping term in the space restricted to the energy range below the gap. We show that the kinetic energy is indeed lowered at the superconducting transition in the t-J model (tJM), which is an effective model defined in the restricted space. That result is in agreement with experimental observations and may be attributed to the formation of spin polarons and the change of roles which are played by the kinetic and the potential energy in the tJM and in some effective model for spin polarons. The total spectral weight represents the kinetic energy in a model defined in a broader space if the upper limit in the integral of the optical conductivity is set above the gap. We demonstrate that the kinetic energy in the Hubbard model is also lowered in the superconducting state. That result does not agree with experimental observations, indicating that the spectral weight is conserved for all temperatures if the upper limit of the integral is set above the charge transfer gap. This discrepancy suggests that a single band model is not capable of describing in some respects the physics of excitations across the gap.
Total Kinetic Energy Release in the Fast Neutron Induced Fission of 235U
NASA Astrophysics Data System (ADS)
Loveland, Walter; Yanez, Ricardo
2016-09-01
We have measured the total kinetic energy (TKE) release, its variance and associated fission product mass distributions for the neutron induced fission of 235U for En = 2-90 MeV using the 2E method. The neutron energies were determined,event by event, by time of flight measurements with the white spectrum neutron beam from LANSCE. The TKE decreases with increasing neutron energy. This TKE decrease is due to increasing symmetric fission (and decreasing asymmetric fission)with increasing neutron energy, in accord with Brosa model predictions. Our measurement of the TKE release for 235U(nth,f) is in excellent agreement with the known value, indicating our measurements are absolute measurements. The TKE variances are sensitive indicators of nth chance fission. Due to the occurrence of nth chance fission and pre-fission neutron emission, the average fissioning system and its excitation energy is a complex function of the incident neutron energy. Detailed comparisons of our data with previous measurements will be made. This work was supported, in part, by the Director, Office of Energy Research, Division of Nuclear Physics of the Office of High Energy and Nuclear Physics of the U.S. Department of Energy under Grant DE-SC0014380.
Limiting Energy Dissipation Induces Glassy Kinetics in Single-Cell High-Precision Responses.
Das, Jayajit
2016-03-08
Single cells often generate precise responses by involving dissipative out-of-thermodynamic-equilibrium processes in signaling networks. The available free energy to fuel these processes could become limited depending on the metabolic state of an individual cell. How does limiting dissipation affect the kinetics of high-precision responses in single cells? I address this question in the context of a kinetic proofreading scheme used in a simple model of early-time T cell signaling. Using exact analytical calculations and numerical simulations, I show that limiting dissipation qualitatively changes the kinetics in single cells marked by emergence of slow kinetics, large cell-to-cell variations of copy numbers, temporally correlated stochastic events (dynamic facilitation), and ergodicity breaking. Thus, constraints in energy dissipation, in addition to negatively affecting ligand discrimination in T cells, can create a fundamental difficulty in determining single-cell kinetics from cell-population results. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Limiting Energy Dissipation Induces Glassy Kinetics in Single-Cell High-Precision Responses
Das, Jayajit
2016-01-01
Single cells often generate precise responses by involving dissipative out-of-thermodynamic-equilibrium processes in signaling networks. The available free energy to fuel these processes could become limited depending on the metabolic state of an individual cell. How does limiting dissipation affect the kinetics of high-precision responses in single cells? I address this question in the context of a kinetic proofreading scheme used in a simple model of early-time T cell signaling. Using exact analytical calculations and numerical simulations, I show that limiting dissipation qualitatively changes the kinetics in single cells marked by emergence of slow kinetics, large cell-to-cell variations of copy numbers, temporally correlated stochastic events (dynamic facilitation), and ergodicity breaking. Thus, constraints in energy dissipation, in addition to negatively affecting ligand discrimination in T cells, can create a fundamental difficulty in determining single-cell kinetics from cell-population results. PMID:26958894
Kinetic-energy induced smoothening and delay of epitaxial breakdown in pulsed-laser deposition
Shin, Byungha; Aziz, Michael J.
2007-08-15
We have isolated the effect of kinetic energy of depositing species from the effect of flux pulsing during pulsed-laser deposition (PLD) on surface morphology evolution of Ge(001) homoepitaxy at low temperature (100 deg. C). Using a dual molecular beam epitaxy (MBE) PLD chamber, we compare morphology evolution from three different growth methods under identical experimental conditions except for the differing nature of the depositing flux: (a) PLD with average kinetic energy 300 eV (PLD-KE); (b) PLD with suppressed kinetic energy comparable to thermal evaporation energy (PLD-TH); and (c) MBE. The thicknesses at which epitaxial breakdown occurs are ranked in the order PLD-KE>MBE>PLD-TH; additionally, the surface is smoother in PLD-KE than in MBE. The surface roughness of the films grown by PLD-TH cannot be compared due to the early epitaxial breakdown. These results demonstrate convincingly that kinetic energy is more important than flux pulsing in the enhancement of epitaxial growth, i.e., the reduction in roughness and the delay of epitaxial breakdown.
Montoya, M.; Rojas, J.; Lobato, I.
2010-08-04
The average of fragment kinetic energy (E-bar sign*) and the multiplicity of prompt neutrons ({nu}(bar sign)) as a function of fragment mass (m*), as well as the fragment mass yield (Y(m*)) from thermal neutron-induced fission of {sup 239}Pu have been measured by Tsuchiya et al.. In that work the mass and kinetic energy are calculated from the measured kinetic energy of one fragment and the difference of time of flight of the two complementary fragments. However they do not present their results about the standard deviation {sigma}{sub E}*(m*). In this work we have made a numerical simulation of that experiment which reproduces its results, assuming an initial distribution of the primary fragment kinetic energy (E(A)) with a constant value of the standard deviation as function of fragment mass ({sigma}{sub E}(A)). As a result of the simulation we obtain the dependence {sigma}{sub E}*(m*) which presents an enhancement between m* = 92 and m* = 110, and a peak at m* = 121.
NASA Astrophysics Data System (ADS)
Montoya, M.; Rojas, J.; Lobato, I.
2010-08-01
The average of fragment kinetic energy (E*) and the multiplicity of prompt neutrons (ν) as a function of fragment mass (m*), as well as the fragment mass yield (Y(m*)) from thermal neutron-induced fission of 239Pu have been measured by Tsuchiya et al.. In that work the mass and kinetic energy are calculated from the measured kinetic energy of one fragment and the difference of time of flight of the two complementary fragments. However they do not present their results about the standard deviation σE*(m*). In this work we have made a numerical simulation of that experiment which reproduces its results, assuming an initial distribution of the primary fragment kinetic energy (E(A)) with a constant value of the standard deviation as function of fragment mass (σE(A)). As a result of the simulation we obtain the dependence σE*(m*) which presents an enhancement between m* = 92 and m* = 110, and a peak at m* = 121.
NASA Astrophysics Data System (ADS)
Huang, Peisheng; Sanford, Thomas B.; Imberger, JöRg
2009-12-01
Heat and turbulent kinetic energy budgets of the ocean surface layer during the passage of Hurricane Frances were examined using a three-dimensional hydrodynamic model. In situ data obtained with the Electromagnetic-Autonomous Profiling Explorer (EM-APEX) floats were used to set up the initial conditions of the model simulation and to compare to the simulation results. The spatial heat budgets reveal that during the hurricane passage, not only the entrainment in the bottom of surface mixed layer but also the horizontal water advection were important factors determining the spatial pattern of sea surface temperature. At the free surface, the hurricane-brought precipitation contributed a negligible amount to the air-sea heat exchange, but the precipitation produced a negative buoyancy flux in the surface layer that overwhelmed the instability induced by the heat loss to the atmosphere. Integrated over the domain within 400 km of the hurricane eye on day 245.71 of 2004, the rate of heat anomaly in the surface water was estimated to be about 0.45 PW (1 PW = 1015 W), with about 20% (0.09 PW in total) of this was due to the heat exchange at the air-sea interface, and almost all the remainder (0.36 PW) was downward transported by oceanic vertical mixing. Shear production was the major source of turbulent kinetic energy amounting 88.5% of the source of turbulent kinetic energy, while the rest (11.5%) was attributed to the wind stirring at sea surface. The increase of ocean potential energy due to vertical mixing represented 7.3% of the energy deposited by wind stress.
1981-02-01
heat of detonation of pentolite is Sl k.J/g, so the kinetic energy of the tungsten penetrators is equal to the heat of detonation of...the heat of detonation of pentolite, 5.11 kJ/g. Then the scaled distance curves 3 can be used to predict blast pressure at the instrumented position for...kinetic and chemical energy is 11.8 MJ which equals the heat of detonation of 2.3 kg of pentolite. This would produce a reflected blast pressure of
Montoya, M.; Rojas, J.; Saetone, E.
2007-10-26
The mass and kinetic energy distribution of nuclear fragments from thermal neutron-induced fission of {sup 235}U(n{sub th},f) have been studied using a Monte-Carlo simulation. Besides reproducing the pronounced broadening in the standard deviation of the kinetic energy at the final fragment mass number around m = 109, our simulation also produces a second broadening around m = 125. These results are in good agreement with the experimental data obtained by Belhafaf et al. and other results on yield of mass. We conclude that the obtained results are a consequence of the characteristics of the neutron emission, the sharp variation in the primary fragment kinetic energy and mass yield curves. We show that because neutron emission is hazardous to make any conclusion on primary quantities distribution of fragments from experimental results on final quantities distributions.
Quantitative Analysis of Clustered DNA Damages Induced by Silicon Beams of Different Kinetic Energy
Keszenman D. J.; Keszenman, D.J.; Bennett, P.V.; Sutherland, B.M.; Wilson, P.F.
2013-05-14
Humans may b exposed to highly energetic charged particle radiation as a result of medical treatments, occupational activitie or accidental events. In recent years, our increasing presence and burgeoning interest in space exploration beyond low Earth orbit has led to a large increase in the research of the biological effects ofcharged particle radiation typical of that encountered in the space radiation environment. The study of the effects of these types of radiation qualities in terms ofDNA damage induction and repair is fundamental to understand mechanisms both underlying their greater biological effectiveness as we)) as the short and long term risks of health effects such as carcinogenesis, degen rative diseases and premature aging. Charged particle radiation induces a variety of DNA alterations, notably bistranded clustered damages, defined as two or more closely-opposed strand break , oxidized bases or abasic sites within a few helical turns. The induction of such highly complex DNA damage enhances the probability of incorrect or incomplete repair and thus constitutes greater potential for genomic instability, cell death and transformation.
Kinetic energy transducing system
Danihel, M.
1986-07-08
A device is described for converting wave energy to mechanical motion comprising: a frame, at least one wave energy transducer each of which has a float to ride upon the undulating surface of a body of water, a rocker shaft rotatably mounted in the frame and connected to the float by a rocker arm to turn in response to movement of the float upon the undulating water surface, a pair of unidirectional clutch mechanisms coupled to the rocker shaft, a drive shaft rotatably mounted on the frame and connected to the clutch mechanisms to turn in a single direction of rotation responsive to alternative engagement of the clutch mechanisms therewith and turning movement of the rocker shaft in both directions of rotation, and a hydrofoil system for each float including a vertical shaft extending downwardly from the bottom of each float, a transverse rod which is rotatably coupled to the vertical shaft, a pair of hydrofoil wings secured to the transverse rod on opposite sides of the vertical shaft, and means for centering the hydrofoil wings acting between the vertical shaft and the transverse rod to urge the hydrofoil wings toward horizontal orientation.
Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go
2016-05-10
It is found that new channels of energy exchange between macro- and microscopic dynamics exist in plasmas. They are induced by macroscopic plasma flow. This finding is based on the kinetic-magnetohydrodynamic (MHD) theory, which analyses interaction between macroscopic (MHD-scale) motion and microscopic (particle-scale) dynamics. The kinetic-MHD theory is extended to include effects of macroscopic plasma flow self-consistently. The extension is realised by generalising an energy exchange term due to wave-particle resonance, denoted by δ WK. The first extension is generalisation of the particle's Lagrangian, and the second one stems from modification to the particle distribution function due to flow. These extensions lead to a generalised expression of δ WK, which affects the MHD stability of plasmas.
Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go
2016-01-01
It is found that new channels of energy exchange between macro- and microscopic dynamics exist in plasmas. They are induced by macroscopic plasma flow. This finding is based on the kinetic-magnetohydrodynamic (MHD) theory, which analyses interaction between macroscopic (MHD-scale) motion and microscopic (particle-scale) dynamics. The kinetic-MHD theory is extended to include effects of macroscopic plasma flow self-consistently. The extension is realised by generalising an energy exchange term due to wave-particle resonance, denoted by δ WK. The first extension is generalisation of the particle’s Lagrangian, and the second one stems from modification to the particle distribution function due to flow. These extensions lead to a generalised expression of δ WK, which affects the MHD stability of plasmas. PMID:27160346
Kinetic energy equations for the average-passage equation system
NASA Technical Reports Server (NTRS)
Johnson, Richard W.; Adamczyk, John J.
1989-01-01
Important kinetic energy equations derived from the average-passage equation sets are documented, with a view to their interrelationships. These kinetic equations may be used for closing the average-passage equations. The turbulent kinetic energy transport equation used is formed by subtracting the mean kinetic energy equation from the averaged total instantaneous kinetic energy equation. The aperiodic kinetic energy equation, averaged steady kinetic energy equation, averaged unsteady kinetic energy equation, and periodic kinetic energy equation, are also treated.
NASA Astrophysics Data System (ADS)
Lu, Yingxian; Wang, Xiaohong; Wu, Xiaoming; Qin, Jin; Lu, Ruochen
2014-06-01
This paper presents a non-resonant, gravity-induced micro triboelectric harvester with high internal resistance. The device collects kinetic energy from low-frequency jiggling movements for the power supply of portable electric devices such as wristwatches. It includes a friction module to produce triboelectric charge and an electrostatic induction module to export energy. The friction that transfers charge is induced by jiggling movements, with gravity and inertia of an internal slider, instead of with external direct force. The non-resonant structure allows the device to respond to low frequencies of 1.5-5.5 Hz, covering the frequencies of human motion. Load resistance sweeping shows that the optimal load resistance is about 1.1 GΩ, with the peak output voltage of about 260 V, and the output power of 60 µW. The proposed harvester responds to low-frequency kinetic energy in jiggling movements matching that of a human limb's running motion; so it has potential to convert the mechanical energy of arm swings or strides into electric energy.
Duke, Dana Lynn
2015-11-12
This Ph.D. dissertation describes a measurement of the change in mass distributions and average total kinetic energy (TKE) release with increasing incident neutron energy for fission of ^{235}U and ^{238}U. Although fission was discovered over seventy-five years ago, open questions remain about the physics of the fission process. The energy of the incident neutron, En, changes the division of energy release in the resulting fission fragments, however, the details of energy partitioning remain ambiguous because the nucleus is a many-body quantum system. Creating a full theoretical model is difficult and experimental data to validate existing models are lacking. Additional fission measurements will lead to higher-quality models of the fission process, therefore improving applications such as the development of next-generation nuclear reactors and defense. This work also paves the way for precision experiments such as the Time Projection Chamber (TPC) for fission cross section measurements and the Spectrometer for Ion Determination in Fission (SPIDER) for precision mass yields.
Keszenman, D.J.; Sutherland, B. M.
2010-08-01
To determine the linear energy transfer (LET) dependence of the biological effects of densely ionizing radiation in relation to changes in the ionization density along the track, we measured the yields and spectrum of clustered DNA damages induced by charged particles of different atomic number but similar kinetic energy per nucleon in different DNA microenvironments. Yeast DNA embedded in agarose in solutions of different free radical scavenging capacity was irradiated with 1 GeV protons, 1 GeV/nucleon oxygen ions, 980 MeV/nucleon titanium ions or 968 MeV/nucleon iron ions. The frequencies of double-strand breaks (DSBs), abasic sites and oxypurine clusters were quantified. The total DNA damage yields per absorbed dose induced in non-radioquenching solution decreased with LET, with minor variations in radioquenching conditions being detected. However, the total damage yields per particle fluence increased with LET in both conditions, indicating a higher efficiency per particle to induce clustered DNA damages. The yields of DSBs and non-DSB clusters as well as the damage spectra varied with LET and DNA milieu, suggesting the involvement of more than one mechanism in the formation of the different types of clustered damages.
Kinetic energy budgets in areas of convection
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.
1979-01-01
Synoptic scale budgets of kinetic energy are computed using 3 and 6 h data from three of NASA's Atmospheric Variability Experiments (AVE's). Numerous areas of intense convection occurred during the three experiments. Large kinetic energy variability, with periods as short as 6 h, is observed in budgets computed over each entire experiment area and over limited volumes that barely enclose the convection and move with it. Kinetic energy generation and transport processes in the smaller volumes are often a maximum when the enclosed storms are near peak intensity, but the nature of the various energy processes differs between storm cases and seems closely related to the synoptic conditions. A commonly observed energy budget for peak storm intensity indicates that generation of kinetic energy by cross-contour flow is the major energy source while dissipation to subgrid scales is the major sink. Synoptic scale vertical motion transports kinetic energy from lower to upper levels of the atmosphere while low-level horizontal flux convergence and upper-level horizontal divergence also occur. Spatial fields of the energy budget terms show that the storm environment is a major center of energy activity for the entire area.
Turbulence kinetic energy equation for dilute suspensions
NASA Technical Reports Server (NTRS)
Abou-Arab, T. W.; Roco, M. C.
1989-01-01
A multiphase turbulence closure model is presented which employs one transport equation, namely the turbulence kinetic energy equation. The proposed form of this equation is different from the earlier formulations in some aspects. The power spectrum of the carrier fluid is divided into two regions, which interact in different ways and at different rates with the suspended particles as a function of the particle-eddy size ratio and density ratio. The length scale is described algebraically. A mass/time averaging procedure for the momentum and kinetic energy equations is adopted. The resulting turbulence correlations are modeled under less retrictive assumptions comparative to previous work. The closures for the momentum and kinetic energy equations are given. Comparisons of the predictions with experimental results on liquid-solid jet and gas-solid pipe flow show satisfactory agreement.
Kinetic-energy-momentum tensor in electrodynamics
NASA Astrophysics Data System (ADS)
Sheppard, Cheyenne J.; Kemp, Brandon A.
2016-01-01
We show that the Einstein-Laub formulation of electrodynamics is invalid since it yields a stress-energy-momentum (SEM) tensor that is not frame invariant. Two leading hypotheses for the kinetic formulation of electrodynamics (Chu and Einstein-Laub) are studied by use of the relativistic principle of virtual power, mathematical modeling, Lagrangian methods, and SEM transformations. The relativistic principle of virtual power is used to demonstrate the field dynamics associated with energy relations within a relativistic framework. Lorentz transformations of the respective SEM tensors demonstrate the relativistic frameworks for each studied formulation. Mathematical modeling of stationary and moving media is used to illustrate the differences and discrepancies of specific proposed kinetic formulations, where energy relations and conservation theorems are employed. Lagrangian methods are utilized to derive the field kinetic Maxwell's equations, which are studied with respect to SEM tensor transforms. Within each analysis, the Einstein-Laub formulation violates special relativity, which invalidates the Einstein-Laub SEM tensor.
Density Scaling of Noninteracting Kinetic Energy Functionals.
Borgoo, Alex; Tozer, David J
2013-05-14
The influence of imposing an approximate density scaling condition on a noninteracting kinetic energy functional is investigated. A simple generalized gradient approximation (GGA) is presented, which satisfies both the density scaling condition and the usual coordinate scaling condition; the remaining multiplicative constant is determined from an energy criterion. In post-Kohn-Sham calculations, noninteracting kinetic energies of the closed-shell molecules of the G1 set determined using the GGA are a modest improvement over those determined using the corresponding local functional, which does not satisfy the density scaling condition. Potential energy curves of CO, F2, and P2 exhibit binding with the GGA, compared to purely repulsive curves with the local functional. Adjusting the exponent in the GGA form in order to optimize energy accuracy violates the density scaling condition, and two of the diatomics no longer exhibit binding. Results are compared with those from other local/GGA functionals in the literature.
Filamentary and hierarchical pictures - Kinetic energy criterion
NASA Technical Reports Server (NTRS)
Klypin, Anatoly A.; Melott, Adrian L.
1992-01-01
We present a new criterion for formation of second-generation filaments. The criterion called the kinetic energy ratio, KR, is based on comparison of peculiar velocities at different scales. We suggest that the clumpiness of the distribution in some cases might be less important than the 'coldness' or 'hotness' of the flow for formation of coherent structures. The kinetic energy ratio is analogous to the Mach number except for one essential difference. If at some scale KR is greater than 1, as estimated at the linear stage, then when fluctuations of this scale reach nonlinearity, the objects they produce must be anisotropic ('filamentary'). In the case of power-law initial spectra the kinetic ratio criterion suggests that the border line is the power-spectrum with the slope n = -1.
Filamentary and hierarchical pictures - Kinetic energy criterion
NASA Technical Reports Server (NTRS)
Klypin, Anatoly A.; Melott, Adrian L.
1992-01-01
We present a new criterion for formation of second-generation filaments. The criterion called the kinetic energy ratio, KR, is based on comparison of peculiar velocities at different scales. We suggest that the clumpiness of the distribution in some cases might be less important than the 'coldness' or 'hotness' of the flow for formation of coherent structures. The kinetic energy ratio is analogous to the Mach number except for one essential difference. If at some scale KR is greater than 1, as estimated at the linear stage, then when fluctuations of this scale reach nonlinearity, the objects they produce must be anisotropic ('filamentary'). In the case of power-law initial spectra the kinetic ratio criterion suggests that the border line is the power-spectrum with the slope n = -1.
Nonlocal kinetic-energy-density functionals
Garcia-Gonzalez, P.; Alvarellos, J.E.; Chacon, E. |
1996-04-01
In this paper we present nonlocal kinetic-energy functionals {ital T}[{ital n}] within the average density approximation (ADA) framework, which do not require any extra input when applied to any electron system and recover the exact kinetic energy and the linear response function of a homogeneous system. In contrast with previous ADA functionals, these present good behavior of the long-range tail of the exact weight function. The averaging procedure for the kinetic functional (averaging the Fermi momentum of the electron gas, instead of averaging the electron density) leads to a functional without numerical difficulties in the calculation of extended systems, and it gives excellent results when applied to atoms and jellium surfaces. {copyright} {ital 1996 The American Physical Society.}
Excess kinetic energy dissipation in materials
Corrales, Louis R.; Chartier, Alain; Devanathan, Ram
2005-01-12
Molecular dynamics computer simulations are used to study the evolution of thermal spikes arising from PKAs in zircon and copper. The effects of thermostats employed to remove energy from the system is characterized and compared to the case where kinetic energy is not removed from the system. Strong effects on the trajectory of the collision sequence is found for zircon, but in contrast, little effects are found for copper.
Energy transfer and kinetics in mechanochemistry.
Chen, Zhiliang; Lu, Shengyong; Mao, Qiongjing; Buekens, Alfons; Wang, Yuting; Yan, Jianhua
2017-09-13
Mechanochemistry (MC) exerts extraordinary degradation and decomposition effects on many chlorinated, brominated, and even fluorinated persistent organic pollutants (POPs). However, its application is still limited by inadequate study of its reaction kinetic aspects. In the present work, the ball motion and energy transfer in planetary ball mill are investigated in some detail. Almost all milling parameters are summarised in a single factor-total effective impact energy. Furthermore, the MC kinetic between calcium oxide/Al and hexachlorobenzene is well established and modelled. The results indicate that total effective impact energy and reagent ratio are the two factors sufficient for describing the MC degradation degree of POPs. The reaction rate constant only depends on the chemical properties of reactants, so it could be used as an important index to appraise the quality of MC additives. This model successfully predicts the reaction rate for different operating conditions, indicating that it could be suitably applied for conducting MC reactions in other reactors.
Conversion of laser energy to gas kinetic energy
NASA Technical Reports Server (NTRS)
Caledonia, G. E.
1976-01-01
Techniques for the gas phase absorption of laser radiation for ultimate conversion to gas kinetic energy are discussed. Particular emphasis is placed on absorption by the vibration rotation bands of diatomic molecules at high pressures. This high pressure absorption appears to offer efficient conversion of laser energy to gas translational energy. Bleaching and chemical effects are minimized and the variation of the total absorption coefficient with temperature is minimal.
Estimation of turbulent kinetic energy dissipation
NASA Astrophysics Data System (ADS)
Chen, Huey-Long; Hondzo, Miki; Rao, A. Ramachandra
2001-06-01
The kinetic energy dissipation rate is one of the key intrinsic fluid flow parameters in environmental fluid dynamics. In an indirect method the kinetic energy dissipation rate is estimated from the Batchelor spectrum. Because the Batchelor spectrum has a significant difference between the highest and lowest spectral values, the spectral bias in the periodogram causes the lower spectral values at higher frequencies to increase. Consequently, the accuracy in fitting the Batchelor spectrum is affected. In this study, the multitaper spectral estimation method is compared to conventional methods in estimating the synthetic temperature gradient spectra. It is shown in the results that the multitaper spectra have less bias than the Hamming window smoothed spectra and the periodogram in estimating the synthetic temperature gradient spectra. The results of fitting the Batchelor spectrum based on four error functions are compared. When the theoretical noise spectrum is available and delineated at the intersection of the estimated spectrum, the fitting results of the kinetic energy dissipation rate corresponding to the four error functions do not have significant differences. However, when the noise spectrum is unknown and part of the Batchelor spectrum overlaps the region where the noise spectrum dominates, the weighted chi-square distributed error function has the best fitting results.
Imperfect dark energy from kinetic gravity braiding
Deffayet, Cédric; Pujolàs, Oriol; Sawicki, Ignacy; Vikman, Alexander E-mail: oriol.pujolas@cern.ch E-mail: alexander.vikman@nyu.edu
2010-10-01
We introduce a large class of scalar-tensor models with interactions containing the second derivatives of the scalar field but not leading to additional degrees of freedom. These models exhibit peculiar features, such as an essential mixing of scalar and tensor kinetic terms, which we have named kinetic braiding. This braiding causes the scalar stress tensor to deviate from the perfect-fluid form. Cosmology in these models possesses a rich phenomenology, even in the limit where the scalar is an exact Goldstone boson. Generically, there are attractor solutions where the scalar monitors the behaviour of external matter. Because of the kinetic braiding, the position of the attractor depends both on the form of the Lagrangian and on the external energy density. The late-time asymptotic of these cosmologies is a de Sitter state. The scalar can exhibit phantom behaviour and is able to cross the phantom divide with neither ghosts nor gradient instabilities. These features provide a new class of models for Dark Energy. As an example, we study in detail a simple one-parameter model. The possible observational signatures of this model include a sizeable Early Dark Energy and a specific equation of state evolving into the final de-Sitter state from a healthy phantom regime.
Kinetic energy in density-functional theory
NASA Astrophysics Data System (ADS)
Nesbet, R. K.
1998-07-01
While Kohn-Sham theory uses the quantum-mechanical operator for kinetic energy, Thomas-Fermi theory replaces this with an effective local potential. If both theories are based on the exact universal density functional defined by Hohenberg-Kohn theory, it is an interesting question whether they should give the same results for N-electron ground states. This question is examined and answered in the negative. The inconsistency is resolved only by extending the definition of functional derivatives to encompass linear operators. An exact theory must incorporate one-electron energies and occupation numbers derived from Kohn-Sham theory.
Kinetic energy recovery systems in motor vehicles
NASA Astrophysics Data System (ADS)
Śliwiński, C.
2016-09-01
The article draws attention to the increasing environmental pollution caused by the development of vehicle transport and motorization. Different types of design solutions used in vehicles for the reduction of fuel consumption, and thereby emission of toxic gasses into the atmosphere, were specified. Historical design solutions concerning energy recovery devices in mechanical vehicles which used flywheels to accumulate kinetic energy were shown. Developmental tendencies in the area of vehicle manufacturing in the form of hybrid electric and electric devices were discussed. Furthermore, designs of energy recovery devices with electrical energy storage from the vehicle braking and shock absorbing systems were presented. A mechanical energy storing device using a flywheel operating under vacuum was presented, as were advantages and disadvantages of both systems, the limitations they impose on individual constructions and safety issues. The paper also discusses a design concept of an energy recovery device in mechanical vehicles which uses torsion springs as the main components of energy accumulation during braking. The desirability of a cooperation of both the mechanical- and electrical energy recovery devices was indicated.
A note on the maintenance of the atmospheric kinetic energy
NASA Technical Reports Server (NTRS)
Chen, T.-C.; Lee, Y.-H.
1982-01-01
The winter simulations of the GLAS climate model and the NCAR community climate model are used to examine the maintenance of the atmospheric kinetic energy. It is found that the kinetic energy is generated in the lower latitudes south of the maximum westerlies, transported northward and then, destroyed in the midlatitudes north of the maximum westerlies. Therefore, the atmospheric kinetic energy is maintained by the counterbalance between the divergence (convergence) of kinetic energy flux and generation (destruction) of kinetic energy in lower (middle) latitudes.
A new definition of the kinetic energy density
NASA Astrophysics Data System (ADS)
Sim, Eunji; Larkin, Joseph; Bock, Charles W.; Burke, Kieron
2002-03-01
A new definition of the point-wise energy density of the Kohn-Sham kinetic energy functional is introduced. This energy density is defined solely in terms of the electronic density and the functional derivative, i.e., the negative of the Kohn-Sham potential. Regardless of the origin or assumptions of any given approximation to the kinetic energy functional, this new kinetic energy density can be extracted and compared with the exact quantity point-by-point in real space. Its properties are discussed. The new energy density is used to discuss convergence of the gradient expansion for the kinetic energy.
Kinetic Approach for Laser-Induced Plasmas
Omar, Banaz; Rethfeld, Baerbel
2008-10-22
Non-equilibrium distribution functions of electron gas and phonon gas excited with ultrashort intense laser pulses are calculated for laser-induced plasmas occurring in solids. The excitation during femtosecond irradiation and the subsequent thermalization of the free electrons, as well as the dynamics of phonons are described by kinetic equations. The microscopic collision processes, such as absorption by inverse bremsstrahlung, electron-electron collisions, and electron-phonon interactions are considered by complete Boltzmann collision integrals. We apply our kinetic approach for gold by taking s-band electron into account and compare it with the case of excitation of d-band electrons.
Kinetic Approach for Laser-Induced Plasmas
NASA Astrophysics Data System (ADS)
Omar, Banaz; Rethfeld, Bärbel
2008-10-01
Non-equilibrium distribution functions of electron gas and phonon gas excited with ultrashort intense laser pulses are calculated for laser-induced plasmas occurring in solids. The excitation during femtosecond irradiation and the subsequent thermalization of the free electrons, as well as the dynamics of phonons are described by kinetic equations. The microscopic collision processes, such as absorption by inverse bremsstrahlung, electron-electron collisions, and electron-phonon interactions are considered by complete Boltzmann collision integrals. We apply our kinetic approach for gold by taking s-band electron into account and compare it with the case of excitation of d-band electrons.
Partitioning kinetic energy during freewheeling wheelchair maneuvers.
Medola, Fausto O; Dao, Phuc V; Caspall, Jayme J; Sprigle, Stephen
2014-03-01
This paper describes a systematic method to partition the kinetic energy (KE) of a free-wheeling wheelchair. An ultralightweight rigid frame wheelchair was instrumented with two axle-mounted encoders and data acquisition equipment to accurately measure the velocity of the drive wheels. A mathematical model was created combining physical specifications and geometry of the wheelchair and its components. Two able-bodied subjects propelled the wheelchair over four courses that involved straight and turning maneuvers at differing speeds. The KE of the wheelchair was divided into three components: translational, rotational, and turning energy. This technique was sensitive to the changing contributions of the three energy components across maneuvers. Translational energy represented the major component of total KE in all maneuvers except a zero radius turn in which turning energy was dominant. Both translational and rotational energies are directly related to wheelchair speed. Partitioning KE offers a useful means of investigating the dynamics of a moving wheelchair. The described technique permits analysis of KE imparted to the wheelchair during maneuvers involving changes in speed and direction, which are most representative of mobility in everyday life. This technique can be used to study the effort required to maneuver different types and configurations of wheelchairs.
On Kinetics Modeling of Vibrational Energy Transfer
NASA Technical Reports Server (NTRS)
Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.
On Kinetics Modeling of Vibrational Energy Transfer
NASA Technical Reports Server (NTRS)
Gilmore, John O.; Sharma, Surendra P.; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Two models of vibrational energy exchange are compared at equilibrium to the elementary vibrational exchange reaction for a binary mixture. The first model, non-linear in the species vibrational energies, was derived by Schwartz, Slawsky, and Herzfeld (SSH) by considering the detailed kinetics of vibrational energy levels. This model recovers the result demanded at equilibrium by the elementary reaction. The second model is more recent, and is gaining use in certain areas of computational fluid dynamics. This model, linear in the species vibrational energies, is shown not to recover the required equilibrium result. Further, this more recent model is inconsistent with its suggested rate constants in that those rate constants were inferred from measurements by using the SSH model to reduce the data. The non-linear versus linear nature of these two models can lead to significant differences in vibrational energy coupling. Use of the contemporary model may lead to significant misconceptions, especially when integrated in computer codes considering multiple energy coupling mechanisms.
Kinetic energy operators in linearized internal coordinates
NASA Astrophysics Data System (ADS)
Pesonen, Janne
2008-01-01
It is customary to describe molecular vibrations using as exact kinetic energy operators and as accurate potentials as possible. It has become a standard approach to express Hamiltonians in curvilinear internal displacement coordinates, because they offer a simple and physical picture of vibrational motions, including large amplitude changes in the shape. In the older normal mode model of molecular vibrations, the nuclei are thought to vibrate infinitesimally about the reference configuration, and the shape of the molecule is described using linearized approximations of the true geometrically defined internal displacement coordinates. It is natural to ask how the two approaches are related. In this work, I present a general yet practical way to obtain curvilinear displacement coordinates as closed function of their linearized counterparts, and vice versa. In contrast to the conventional power series approach, the body-frame dependency is explicitly taken into account, and the relations are valid for any value of the coordinates. The present approach also allows one to obtain easily exact kinetic energy operators in linearized shape coordinates.
Conversion of laser energy to gas kinetic energy
NASA Technical Reports Server (NTRS)
Caledonia, G. E.
1975-01-01
Techniques for the gas phase absorption of laser radiation for conversion to gas kinetic energy are discussed. Absorption by inverse Bremsstrahlung, in which laser energy is converted at a gas kinetic rate in a spectrally continuous process, is briefly described, and absorption by molecular vibrational rotation bands is discussed at length. High pressure absorption is proposed as a means of minimizing gas bleaching and dissociation, the major disadvantages of the molecular absorption process. A band model is presented for predicting the molecular absorption spectra in the high pressure absorption region and is applied to the CO molecule. Use of a rare gas seeded with Fe(CO)5 for converting vibrational modes to translation modes is described.
Kinetic energy decomposition scheme based on information theory.
Imamura, Yutaka; Suzuki, Jun; Nakai, Hiromi
2013-12-15
We proposed a novel kinetic energy decomposition analysis based on information theory. Since the Hirshfeld partitioning for electron densities can be formulated in terms of Kullback-Leibler information deficiency in information theory, a similar partitioning for kinetic energy densities was newly proposed. The numerical assessments confirm that the current kinetic energy decomposition scheme provides reasonable chemical pictures for ionic and covalent molecules, and can also estimate atomic energies using a correction with viral ratios. Copyright © 2013 Wiley Periodicals, Inc.
Conversion of laser energy to gas kinetic energy
NASA Technical Reports Server (NTRS)
Caledonia, G. E.
1977-01-01
Techniques for the gas-phase absorption of laser energy with ultimate conversion to heat or directed kinetic energy are reviewed. It is shown that the efficiency of resonance absorption by the vibration/rotation bands of the working gas can be enhanced by operating at sufficiently high pressures so that the linewidths of the absorbing transition exceed the line spacing. Within this limit, the gas can absorb continuously over the full spectral region of the band, and bleaching can be minimized since the manifold of molecular vibrational levels can simultaneously absorb the laser radiation.
Conversion of laser energy to gas kinetic energy
NASA Technical Reports Server (NTRS)
Caledonia, G. E.
1977-01-01
Techniques for the gas-phase absorption of laser energy with ultimate conversion to heat or directed kinetic energy are reviewed. It is shown that the efficiency of resonance absorption by the vibration/rotation bands of the working gas can be enhanced by operating at sufficiently high pressures so that the linewidths of the absorbing transition exceed the line spacing. Within this limit, the gas can absorb continuously over the full spectral region of the band, and bleaching can be minimized since the manifold of molecular vibrational levels can simultaneously absorb the laser radiation.
Magkos, Faidon; Mohammed, B Selma; Patterson, Bruce W; Mittendorfer, Bettina
2009-09-01
Free fatty acid (FFA) availability increases several-fold during exercise and remains significantly elevated for at least 3 to 6 hours after exercise cessation. Little, however, is known regarding the duration of the postexercise rise in FFA flux. In the present study, we used stable isotope-labeled palmitate infusion to examine fatty acid metabolism in 27 healthy untrained men and women (age, 29 +/- 7 years; body mass index, 25 +/- 4 kg/m2) between 13 to 16 hours and 21 to 24 hours after a single bout of moderate-intensity endurance exercise (1-2 hours at 60% of peak oxygen consumption), performed in the evening, and after a time-matched resting trial. Postabsorptive FFA rate of appearance (Ra) and FFA concentration in plasma were significantly greater after exercise than rest throughout the recovery period (P < .015), but the exercise-induced increases declined from approximately 40% at 13 to 16 hours to approximately 10% at 21 to 24 hours postexercise (P = .001). The magnitude of the exercise-induced increase in plasma FFA concentration was proportional to the increase in FFA Ra. Correlation analysis demonstrated that exercise-induced changes in plasma FFA Ra at 13 to 16 hours are (1) negatively associated with resting plasma FFA Ra and (2) positively associated with the net energy expenditure of exercise and the exercise-induced changes in whole-body fat oxidation rate (all P values < .05). In multivariate stepwise linear regression analysis, baseline plasma FFA Ra (P < or = .008) and net energy expenditure of exercise (P < or = .005) independently predicted the exercise-induced change in plasma FFA Ra at 13 to 16 hours. We conclude that the exercise-induced increase in FFA mobilization is (1) long-lived, persisting for 12 to 24 hours after exercise, with a progressive decline with time; (2) greater in subjects with low than high resting plasma FFA availability; and (3) greater after exercise with high than low energy demand.
Trends in Southern Ocean Eddy Kinetic Energy
NASA Astrophysics Data System (ADS)
Chambers, Don
2016-04-01
A recent study by Hogg et al. (JGR, 2015) has demonstrated a 20-year trend in eddy kinetic energy (EKE) computed from satellite altimetry data. However, this estimate is based on an averaging over large spatial areas. In this study, we use the same methods to examine regional EKE trends throughout the Southern Ocean, from 1993-2015. We do find significant positive trends in several areas of the Southern Ocean, mainly in regions with high mean EKE associated with interactions between jets and bathymetry. At the same time, however, there are also regions with significant negative trends. Overall, EKE in the majority of the Southern Ocean has not changed. These results suggest that the estimates of Hogg et al. may have been biased by these regional extremes, and that more work is needed to quantify climatic changes in EKE.
Electron acceleration and kinetic energy tailoring via ultrafast terahertz fields.
Greig, S R; Elezzabi, A Y
2014-11-17
We propose a mechanism for tuning the kinetic energy of surface plasmon generated electron pulses through control of the time delay between a pair of externally applied terahertz pulses. Varying the time delay results in translation, compression, and broadening of the kinetic energy spectrum of the generated electron pulse. We also observe that the electrons' kinetic energy dependence on the carrier envelope phase of the surface plasmon is preserved under the influence of a terahertz electric field.
Cascade of kinetic energy in three-dimensional compressible turbulence.
Wang, Jianchun; Yang, Yantao; Shi, Yipeng; Xiao, Zuoli; He, X T; Chen, Shiyi
2013-05-24
The conservative cascade of kinetic energy is established using both Fourier analysis and a new exact physical-space flux relation in a simulated compressible turbulence. The subgrid scale (SGS) kinetic energy flux of the compressive mode is found to be significantly larger than that of the solenoidal mode in the inertial range, which is the main physical origin for the occurrence of Kolmogorov's -5/3 scaling of the energy spectrum in compressible turbulence. The perfect antiparallel alignment between the large-scale strain and the SGS stress leads to highly efficient kinetic energy transfer in shock regions, which is a distinctive feature of shock structures in comparison with vortex structures. The rescaled probability distribution functions of SGS kinetic energy flux collapse in the inertial range, indicating a statistical self-similarity of kinetic energy cascades.
Kinetic energy budget studies of areas of convection
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.
1979-01-01
Synoptic-scale kinetic energy budgets are being computed for three cases when large areas of intense convection occurred over the Central United States. Major energy activity occurs in the storm areas.
NASA Astrophysics Data System (ADS)
Duke, D. L.; Tovesson, F.; Brys, T.; Geppert-Kleinrath, V.; Hambsch, F.-J.; Laptev, A.; Meharchand, R.; Manning, B.; Mayorov, D.; Meierbachtol, K.; Mosby, S.; Perdue, B.; Richman, D.; Shields, D.; Vidali, M.
2017-09-01
The average Total Kinetic Energy (TKE) release and fission-fragment yields in neutron-induced fission of 235U and 238U was measured using a Frisch-gridded ionization chamber. These observables are important nuclear data quantites that are relevant to applications and for informing the next generation of fission models. The measurements were performed a the Los Alamos Neutron Science Center and cover En = 200 keV - 30 MeV. The double-energy (2E) method was used to determine the fission-fragment yields and two methods of correcting for prompt-neutron emission were explored. The results of this study are correlated mass and TKE data.
Determination of kinetic energy applied by center pivot sprinklers
USDA-ARS?s Scientific Manuscript database
The kinetic energy of discrete drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. Under center pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy development can...
The Kinetic Energy of a Rotating Figure Skater.
ERIC Educational Resources Information Center
Chen, Wei R.; Troelstra, Arne A.
1998-01-01
When a rotating figure skater's fully extended arms are pulled back toward the torso, the angular velocity is noticeably increased and the kinetic energy of the skater can also be shown to increase. Discusses the change of the kinetic energy during such a process, and the work necessary for such an increase is derived using a dynamic equilibrium…
Droplet Kinetic Energy from Center-Pivot Sprinklers
USDA-ARS?s Scientific Manuscript database
The kinetic energy of discrete water drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. Under center-pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy developmen...
The Kinetic Energy of a Rotating Figure Skater.
ERIC Educational Resources Information Center
Chen, Wei R.; Troelstra, Arne A.
1998-01-01
When a rotating figure skater's fully extended arms are pulled back toward the torso, the angular velocity is noticeably increased and the kinetic energy of the skater can also be shown to increase. Discusses the change of the kinetic energy during such a process, and the work necessary for such an increase is derived using a dynamic equilibrium…
Kinetic energy budgets in areas of intense convection
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Berecek, E. M.; Ebel, D. M.; Jedlovec, G. J.
1980-01-01
A kinetic energy budget analysis of the AVE-SESAME 1 period which coincided with the deadly Red River Valley tornado outbreak is presented. Horizontal flux convergence was found to be the major kinetic energy source to the region, while cross contour destruction was the major sink. Kinetic energy transformations were dominated by processes related to strong jet intrusion into the severe storm area. A kinetic energy budget of the AVE 6 period also is presented. The effects of inherent rawinsonde data errors on widely used basic kinematic parameters, including velocity divergence, vorticity advection, and kinematic vertical motion are described. In addition, an error analysis was performed in terms of the kinetic energy budget equation. Results obtained from downward integration of the continuity equation to obtain kinematic values of vertical motion are described. This alternate procedure shows promising results in severe storm situations.
Zero kinetic energy photoelectron spectroscopy of pyrene.
Zhang, Jie; Han, Fangyuan; Kong, Wei
2010-10-28
We report zero kinetic energy photoelectron (ZEKE) spectroscopy of pyrene via resonantly enhanced multiphoton ionization. Our analysis centers on the symmetry of the first electronically excited state (S(1)), its vibrational modes, and the vibration of the ground cationic state (D(0)). From comparisons between the observed vibrational frequencies and those from ab initio calculations at the configuration interaction singles level using the 6-311G (d,p) basis set, and based on other previous experimental and theoretical reports, we confirm the (1)B(2u) symmetry for the S(1) state. This assignment represents a reversal in the energy order of the two closely spaced electronically excited states from our theoretical calculation, and extensive configuration interactions are attributed to this result. Among the observed vibrational levels of the S(1) state, three are results of vibronic coupling due to the nearby second electronically excited state. The ZEKE spectroscopy obtained via the vibronic levels of the S(1) state reveals similar modes for the cation as those of the intermediate state. Although we believe that the ground ionic state can be considered a single electron configuration, the agreement between theoretical and experimental frequencies for the cation is limited. This result is somewhat surprising based on our previous work on cata-condensed polycyclic aromatic hydrocarbons and small substituted aromatic compounds. Although a relatively small molecule, pyrene demonstrates its nonrigidity via several out-of-plane bending modes corresponding to corrugation of the molecular plane. The adiabatic ionization potential of neutral pyrene is determined to be 59 888 ± 7 cm(-1).
Effective kinetic energy harvesting via structural instabilities
NASA Astrophysics Data System (ADS)
Haji Hosseinloo, Ashkan; Turitsyn, Konstantin
2017-04-01
Vibration energy harvesting has been shown as a promising power source for many small-scale applications mainly because of the considerable reduction in the energy consumption of the electronics, ease of fabrication and implementation of smart materials at small scale, and scalability issues of the conventional batteries. However, conventional energy harvesters are not quite robust to changes in excitation or system parameters, suffer from narrow bandwidth, and are very inefficient at small scale for low frequency harvesting. In addition, they have a low power to volume ratio. To remedy the robustness issues, improve their effectiveness, and increase their power density, we propose to exploit structural instabilities, in particular instabilities in multi-layered composites which are inherently non-resonant. The induced large strains as a result of the structural instability could be exploited to give rise to large strains in an attached piezoelectric layer to generate charge and, hence, energy. The regular high-strain morphological patterns occur throughout the whole composite structure that in turn enable harvesting at a larger volume compared to conventional harvesters; hence, harvesting via structural instabilities can significantly improve the harvested power to volume ratio. In this study, we focus on harvesting from wrinkling type of instabilities.
Feynman and the kinetic energy of an ice skater
NASA Astrophysics Data System (ADS)
Pérez, José-Philippe
2016-01-01
By employing the angular momentum and mechanical energy theorems, we analyse the increase of the angular velocity for an ice skater who changes his arms, initially in an horizontal position, along the axis of the body, first with respect to the lab frame, in which a variation of kinetic energy is observed, and then with respect to the rotating frame moving with the skater. In the last one, while there is no variation of kinetic energy between initial and final positions, the work of the centrifugal force is the opposite to the variation of kinetic energy in the lab frame. We discuss the explanation given by Richard Feynman in his Mechanics course.
Energy transfer, pressure tensor, and heating of kinetic plasma
NASA Astrophysics Data System (ADS)
Yang, Yan; Matthaeus, William H.; Parashar, Tulasi N.; Haggerty, Colby C.; Roytershteyn, Vadim; Daughton, William; Wan, Minping; Shi, Yipeng; Chen, Shiyi
2017-07-01
Kinetic plasma turbulence cascade spans multiple scales ranging from macroscopic fluid flow to sub-electron scales. Mechanisms that dissipate large scale energy, terminate the inertial range cascade, and convert kinetic energy into heat are hotly debated. Here, we revisit these puzzles using fully kinetic simulation. By performing scale-dependent spatial filtering on the Vlasov equation, we extract information at prescribed scales and introduce several energy transfer functions. This approach allows highly inhomogeneous energy cascade to be quantified as it proceeds down to kinetic scales. The pressure work, - ( P . ∇ ) . u , can trigger a channel of the energy conversion between fluid flow and random motions, which contains a collision-free generalization of the viscous dissipation in collisional fluid. Both the energy transfer and the pressure work are strongly correlated with velocity gradients.
Zero kinetic energy photoelectron spectroscopy of triphenylene
Harthcock, Colin; Zhang, Jie; Kong, Wei
2014-06-28
We report vibrational information of both the first electronically excited state and the ground cationic state of jet-cooled triphenylene via the techniques of resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. The first excited electronic state S{sub 1} of the neutral molecule is of A{sub 1}′ symmetry and is therefore electric dipole forbidden in the D{sub 3h} group. Consequently, there are no observable Franck-Condon allowed totally symmetric a{sub 1}′ vibrational bands in the REMPI spectrum. All observed vibrational transitions are due to Herzberg-Teller vibronic coupling to the E′ third electronically excited state S{sub 3}. The assignment of all vibrational bands as e′ symmetry is based on comparisons with calculations using the time dependent density functional theory and spectroscopic simulations. When an electron is eliminated, the molecular frame undergoes Jahn-Teller distortion, lowering the point group to C{sub 2v} and resulting in two nearly degenerate electronic states of A{sub 2} and B{sub 1} symmetry. Here we follow a crude treatment by assuming that all e′ vibrational modes resolve into b{sub 2} and a{sub 1} modes in the C{sub 2v} molecular frame. Some observed ZEKE transitions are tentatively assigned, and the adiabatic ionization threshold is determined to be 63 365 ± 7 cm{sup −1}. The observed ZEKE spectra contain a consistent pattern, with a cluster of transitions centered near the same vibrational level of the cation as that of the intermediate state, roughly consistent with the propensity rule. However, complete assignment of the detailed vibrational structure due to Jahn-Teller coupling requires much more extensive calculations, which will be performed in the future.
Zero kinetic energy photoelectron spectroscopy of triphenylene
NASA Astrophysics Data System (ADS)
Harthcock, Colin; Zhang, Jie; Kong, Wei
2014-06-01
We report vibrational information of both the first electronically excited state and the ground cationic state of jet-cooled triphenylene via the techniques of resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. The first excited electronic state S1 of the neutral molecule is of A1' symmetry and is therefore electric dipole forbidden in the D3h group. Consequently, there are no observable Franck-Condon allowed totally symmetric a1' vibrational bands in the REMPI spectrum. All observed vibrational transitions are due to Herzberg-Teller vibronic coupling to the E' third electronically excited state S3. The assignment of all vibrational bands as e' symmetry is based on comparisons with calculations using the time dependent density functional theory and spectroscopic simulations. When an electron is eliminated, the molecular frame undergoes Jahn-Teller distortion, lowering the point group to C2v and resulting in two nearly degenerate electronic states of A2 and B1 symmetry. Here we follow a crude treatment by assuming that all e' vibrational modes resolve into b2 and a1 modes in the C2v molecular frame. Some observed ZEKE transitions are tentatively assigned, and the adiabatic ionization threshold is determined to be 63 365 ± 7 cm-1. The observed ZEKE spectra contain a consistent pattern, with a cluster of transitions centered near the same vibrational level of the cation as that of the intermediate state, roughly consistent with the propensity rule. However, complete assignment of the detailed vibrational structure due to Jahn-Teller coupling requires much more extensive calculations, which will be performed in the future.
Zero kinetic energy photoelectron spectroscopy of triphenylene.
Harthcock, Colin; Zhang, Jie; Kong, Wei
2014-06-28
We report vibrational information of both the first electronically excited state and the ground cationic state of jet-cooled triphenylene via the techniques of resonantly enhanced multiphoton ionization (REMPI) and zero kinetic energy (ZEKE) photoelectron spectroscopy. The first excited electronic state S1 of the neutral molecule is of A1' symmetry and is therefore electric dipole forbidden in the D3h group. Consequently, there are no observable Franck-Condon allowed totally symmetric a1' vibrational bands in the REMPI spectrum. All observed vibrational transitions are due to Herzberg-Teller vibronic coupling to the E' third electronically excited state S3. The assignment of all vibrational bands as e' symmetry is based on comparisons with calculations using the time dependent density functional theory and spectroscopic simulations. When an electron is eliminated, the molecular frame undergoes Jahn-Teller distortion, lowering the point group to C2v and resulting in two nearly degenerate electronic states of A2 and B1 symmetry. Here we follow a crude treatment by assuming that all e' vibrational modes resolve into b2 and a1 modes in the C2v molecular frame. Some observed ZEKE transitions are tentatively assigned, and the adiabatic ionization threshold is determined to be 63 365 ± 7 cm(-1). The observed ZEKE spectra contain a consistent pattern, with a cluster of transitions centered near the same vibrational level of the cation as that of the intermediate state, roughly consistent with the propensity rule. However, complete assignment of the detailed vibrational structure due to Jahn-Teller coupling requires much more extensive calculations, which will be performed in the future.
Spectral kinetic energy transfer in turbulent premixed reacting flows.
Towery, C A Z; Poludnenko, A Y; Urzay, J; O'Brien, J; Ihme, M; Hamlington, P E
2016-05-01
Spectral kinetic energy transfer by advective processes in turbulent premixed reacting flows is examined using data from a direct numerical simulation of a statistically planar turbulent premixed flame. Two-dimensional turbulence kinetic-energy spectra conditioned on the planar-averaged reactant mass fraction are computed through the flame brush and variations in the spectra are connected to terms in the spectral kinetic energy transport equation. Conditional kinetic energy spectra show that turbulent small-scale motions are suppressed in the burnt combustion products, while the energy content of the mean flow increases. An analysis of spectral kinetic energy transfer further indicates that, contrary to the net down-scale transfer of energy found in the unburnt reactants, advective processes transfer energy from small to large scales in the flame brush close to the products. Triadic interactions calculated through the flame brush show that this net up-scale transfer of energy occurs primarily at spatial scales near the laminar flame thermal width. The present results thus indicate that advective processes in premixed reacting flows contribute to energy backscatter near the scale of the flame.
Kinetic Energy Principle And Neoclassical Toroidal Torque In Tokamaks
Jong-Kyu Park
2011-11-07
It is shown that when tokamaks are perturbed the kinetic energy principle is closely related to the neoclassical toroidal torque by the action invariance of particles. Especially when tokamaks are perturbed from scalar pressure equilibria, the imaginary part of the potential energy in the kinetic energy principle is equivalent to the toroidal torque by the Neoclassical Toroidal Viscosity (NTV). A unified description therefore should be made for both physics. It is also shown in this case that the potential energy operator can be self-adjoint and thus the stability calculation can be simplified by minimizing the potential energy
Kinetic energy principle and neoclassical toroidal torque in tokamaks
Park, Jong-Kyu
2011-11-15
It is shown that when tokamaks are perturbed, the kinetic energy principle is closely related to the neoclassical toroidal torque by the action invariance of particles. Especially when tokamaks are perturbed from scalar pressure equilibria, the imaginary part of the potential energy in the kinetic energy principle is equivalent to the toroidal torque by the neoclassical toroidal viscosity. A unified description therefore should be made for both physics. It is also shown in this case that the potential energy operator can be self-adjoint and thus the stability calculation can be simplified by minimizing the potential energy.
On the Linearly-Balanced Kinetic Energy Spectrum
NASA Technical Reports Server (NTRS)
Lu, Huei,-Iin; Robertson, F. R.
1999-01-01
It is well known that the earth's atmospheric motion can generally be characterized by the two dimensional quasi-geostrophic approximation, in which the constraints on global integrals of kinetic energy, entrophy and potential vorticity play very important roles in redistributing the wave energy among different scales of motion. Assuming the hypothesis of Kolmogrov's local isotropy, derived a -3 power law of the equilibrium two-dimensional kinetic energy spectrum that entails constant vorticity and zero energy flows from the energy-containing wave number up to the viscous cutoff. In his three dimensional quasi-geostrophic theory, showed that the spectrum function of the vertical scale turbulence - expressible in terms of the available potential energy - possesses the same power law as the two dimensional kinetic energy spectrum. As the slope of kinetic energy spectrum in the inertial range is theoretically related to the predictability of the synoptic scales (Lorenz, 1969), many general circulation models includes a horizontal diffusion to provide reasonable kinetic energy spectra, although the actual power law exhibited in the atmospheric general circulation is controversial. Note that in either the atmospheric modeling or the observational analyses, the proper choice of wave number Index to represent the turbulence scale Is the degree of the Legendre polynomial.
On the Linearly-Balanced Kinetic Energy Spectrum
NASA Technical Reports Server (NTRS)
Lu, Huei,-Iin; Robertson, F. R.
1999-01-01
It is well known that the earth's atmospheric motion can generally be characterized by the two dimensional quasi-geostrophic approximation, in which the constraints on global integrals of kinetic energy, entrophy and potential vorticity play very important roles in redistributing the wave energy among different scales of motion. Assuming the hypothesis of Kolmogrov's local isotropy, derived a -3 power law of the equilibrium two-dimensional kinetic energy spectrum that entails constant vorticity and zero energy flows from the energy-containing wave number up to the viscous cutoff. In his three dimensional quasi-geostrophic theory, showed that the spectrum function of the vertical scale turbulence - expressible in terms of the available potential energy - possesses the same power law as the two dimensional kinetic energy spectrum. As the slope of kinetic energy spectrum in the inertial range is theoretically related to the predictability of the synoptic scales (Lorenz, 1969), many general circulation models includes a horizontal diffusion to provide reasonable kinetic energy spectra, although the actual power law exhibited in the atmospheric general circulation is controversial. Note that in either the atmospheric modeling or the observational analyses, the proper choice of wave number Index to represent the turbulence scale Is the degree of the Legendre polynomial.
Transition of energy transfer from MHD turbulence to kinetic plasma
NASA Astrophysics Data System (ADS)
Yang, Yan; Matthaeus, William; Parashar, Tulasi; Shi, Yipeng; Wan, Minping; Chen, Shiyi
2016-11-01
The classical energy cascade scenario is of great importance in explaining the heating of corona and solar wind. One can envision that energy residing in large-scale fluctuations is transported to smaller scales where dissipation occurs and finally drives kinetic processes that absorb the energy flux and energize charged particles. Here we inquire how the cascade operates in a compressible plasma, and how the characteristics of energy transfer vary going from MHD to kinetic scales. When filtering MHD equations, we can get an apparent inertial range over which the conservative energy cascade occurs and the scale locality of energy transfer is similar to the cases of incompressible MHD turbulence. Pervasive shocks not only make a significant difference on energy cascade and magnetic amplification, but can also introduce considerable pressure dilation, a complement of viscous and ohmic dissipation that can trigger an alternative channel of the conversion between kinetic and internal energy. The procedure can also be applied to the Vlasov equation and kinetic simulation, in comparison with MHD turbulence, and is a good candidate to investigate the energy cascade process and the analogous role of the (tensor) pressure dilation in collisionless plasma.
Renormalizing the Kinetic Energy Operator in Elementary Quantum Mechanics
ERIC Educational Resources Information Center
Coutinho, F. A. B.; Amaku, M.
2009-01-01
In this paper, we consider solutions to the three-dimensional Schrodinger equation of the form [psi](r) = u(r)/r, where u(0) [is not equal to] 0. The expectation value of the kinetic energy operator for such wavefunctions diverges. We show that it is possible to introduce a potential energy with an expectation value that also diverges, exactly…
Renormalizing the Kinetic Energy Operator in Elementary Quantum Mechanics
ERIC Educational Resources Information Center
Coutinho, F. A. B.; Amaku, M.
2009-01-01
In this paper, we consider solutions to the three-dimensional Schrodinger equation of the form [psi](r) = u(r)/r, where u(0) [is not equal to] 0. The expectation value of the kinetic energy operator for such wavefunctions diverges. We show that it is possible to introduce a potential energy with an expectation value that also diverges, exactly…
On the total kinetic energy of our Galaxy
NASA Astrophysics Data System (ADS)
Ninkovic, Slobodan
1992-03-01
The total kinetic energy of the Galaxy is estimated from the potential energy by applying the virial theorem. The limits of the potential energy depend strongly on the value of the local escape velocity. They are estimated to be between (-7 and -1) x 10 exp 16 solar mass sq km/sec sq (escape velocity approximately between 450 km/s and 600 km/s). The specific kinetic energy of the Galaxy as a whole is most likely about 21,000 sq km/sec sq, being equally distributed among the subsystems, if the local escape velocity is near its lower limit; the higher the local escape velocity is, the higher is the specific kinetic energy of the Galaxy due to the influence of the dark corona. The specific kinetic energy of the dark corona tends to become equal to that of the Galaxy as a whole for very high values of the local escape velocity. For the purpose of estimating the total potential energy of the Galaxy, inter alia, a model of the Milky Way is developed which yields both the potential and the density analytically so that it is suitable for calculating the galactocentric orbits.
Reaction wheels for kinetic energy storage
NASA Technical Reports Server (NTRS)
Studer, P. A.
1984-01-01
In contrast to all existing reaction wheel implementations, an order of magnitude increase in speed can be obtained efficiently if power to the actuators can be recovered. This allows a combined attitude control-energy storage system to be developed with structure mounted reaction wheels. The feasibility of combining reaction wheels with energy storage wwheels is demonstrated. The power required for control torques is a function of wheel speed but this energy is not dissipated; it is stored in the wheel. The I(2)R loss resulting from a given torque is shown to be constant, independent of the design speed of the motor. What remains, in order to efficiently use high speed wheels (essential for energy storage) for control purposes, is to reduce rotational losses to acceptable levels. Progress was made in permanent magnet motor design for high speed operation. Variable field motors offer more control flexibility and efficiency over a broader speed range.
Reaction wheels for kinetic energy storage
Studer, P.A.
1984-11-01
In contrast to all existing reaction wheel implementations, an order of magnitude increase in speed can be obtained efficiently if power to the actuators can be recovered. This allows a combined attitude control-energy storage system to be developed with structure mounted reaction wheels. The feasibility of combining reaction wheels with energy storage wheels is demonstrated. The power required for control torques is a function of wheel speed but this energy is not dissipated it is stored in the wheel. The I(2)R loss resulting from a given torque is shown to be constant, independent of the design speed of the motor. What remains, in order to efficiently use high speed wheels (essential for energy storage) for control purposes, is to reduce rotational losses to acceptable levels. Progress was made in permanent magnet motor design for high speed operation. Variable field motors offer more control flexibility and efficiency over a broader speed range.
A Note on Kinetic Energy, Dissipation and Enstrophy
NASA Technical Reports Server (NTRS)
Wu, Jie-Zhi; Zhou, Ye; Fan, Meng
1998-01-01
The dissipation rate of a Newtonian fluid with constant shear viscosity can be shown to include three constituents: dilatation, vorticity, and surface strain. The last one is found to make no contributions to the change of kinetic energy. These dissipation constituents arc used to identify typical compact turbulent flow structures at high Reynolds numbers. The incompressible version of the simplified kinetic-energy equation is then cast to a novel form, which is free from the work rate done by surface stresses but in which the full dissipation re-enters.
Energy landscapes, folding mechanisms, and kinetics of RNA tetraloop hairpins.
Chakraborty, Debayan; Collepardo-Guevara, Rosana; Wales, David J
2014-12-31
RNA hairpins play a pivotal role in a diverse range of cellular functions, and are integral components of ribozymes, mRNA, and riboswitches. However, the mechanistic and kinetic details of RNA hairpin folding, which are key determinants of most of its biological functions, are poorly understood. In this work, we use the discrete path sampling (DPS) approach to explore the energy landscapes of two RNA tetraloop hairpins, and provide insights into their folding mechanisms and kinetics in atomistic detail. Our results show that the potential energy landscapes have a distinct funnel-like bias toward the folded hairpin state, consistent with efficient structure-seeking properties. Mechanistic and kinetic information is analyzed in terms of kinetic transition networks. We find microsecond folding times, consistent with temperature jump experiments, for hairpin folding initiated from relatively compact unfolded states. This process is essentially driven by an initial collapse, followed by rapid zippering of the helix stem in the final phase. Much lower folding rates are predicted when the folding is initiated from extended chains, which undergo longer excursions on the energy landscape before nucleation events can occur. Our work therefore explains recent experiments and coarse-grained simulations, where the folding kinetics exhibit precisely this dependency on the initial conditions.
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Browning, P. A.
1983-01-01
Contributions of divergent and rotational wind components to the synoptic-scale kinetic energy balance are described using rawinsonde data at 3 and 6 h intervals from NASA's fourth Atmospheric Variability experiment. Two intense thunderstorm complexes occurred during the period. Energy budgets are described for the entire computational region and for limited volumes that enclosed storm-induced, upper level wind maxima located poleward of convection. Although small in magnitude, the divergent wind component played an important role in the cross-contour generation and horizontal flux divergence of kinetic energy. The importance of V(D) appears directly related to the presence and intensity of convection. Although K(D) usually comprised less than 10 percent of the total kinetic energy content, generation of kinetic energy by V(D) was a major factor in the creation of upper-level wind maxima to the north of the storm complexes. Omission of the divergent wind apparently would lead to serious misrepresentations of the energy balance. A random error analysis is presented to assess confidence limits in the various energy parameters.
Evaluating rainfall kinetic energy - intensity relationships with observed disdrometric data
NASA Astrophysics Data System (ADS)
Angulo-Martinez, Marta; Begueria, Santiago; Latorre, Borja
2016-04-01
Rainfall kinetic energy is required for determining erosivity, the ability of rainfall to detach soil particles and initiate erosion. Its determination relay on the use of disdrometers, i.e. devices capable of measuring the drop size distribution and velocity of falling raindrops. In the absence of such devices, rainfall kinetic energy is usually estimated with empirical expressions relating rainfall energy and intensity. We evaluated the performance of 14 rainfall energy equations in estimating one-minute rainfall energy and event total energy, in comparison with observed data from 821 rainfall episodes (more than 100 thousand one-minute observations) by means of an optical disdrometer. In addition, two sources of bias when using such relationships were evaluated: i) the influence of using theoretical terminal raindrop fall velocities instead of measured values; and ii) the influence of time aggregation (rainfall intensity data every 5-, 10-, 15-, 30-, and 60-minutes). Empirical relationships did a relatively good job when complete events were considered (R2 > 0.82), but offered poorer results for within-event (one-minute resolution) variation. Also, systematic biases where large for many equations. When raindrop size distribution was known, estimating the terminal fall velocities by empirical laws produced good results even at fine time resolution. The influence of time aggregation was very high in the estimated kinetic energy, although linear scaling may allow empirical correction. This results stress the importance of considering all these effects when rainfall energy needs to be estimated from more standard precipitation records. , and recommends the use of disdrometer data to locally determine rainfall kinetic energy.
Mass, Momentum and Kinetic Energy of a Relativistic Particle
ERIC Educational Resources Information Center
Zanchini, Enzo
2010-01-01
A rigorous definition of mass in special relativity, proposed in a recent paper, is recalled and employed to obtain simple and rigorous deductions of the expressions of momentum and kinetic energy for a relativistic particle. The whole logical framework appears as the natural extension of the classical one. Only the first, second and third laws of…
Mass, Momentum and Kinetic Energy of a Relativistic Particle
ERIC Educational Resources Information Center
Zanchini, Enzo
2010-01-01
A rigorous definition of mass in special relativity, proposed in a recent paper, is recalled and employed to obtain simple and rigorous deductions of the expressions of momentum and kinetic energy for a relativistic particle. The whole logical framework appears as the natural extension of the classical one. Only the first, second and third laws of…
Unified Technical Concepts. Module 7: Potential and Kinetic Energy.
ERIC Educational Resources Information Center
Technical Education Research Center, Waco, TX.
This concept module on potential and kinetic energy is one of thirteen modules that provide a flexible, laboratory-based physics instructional package designed to meet the specialized needs of students in two-year, postsecondary technical schools. Each of the thirteen concept modules discusses a single physics concept and how it is applied to each…
Momentum and Kinetic Energy: Confusable Concepts in Secondary School Physics
ERIC Educational Resources Information Center
Bryce, T. G. K.; MacMillan, K.
2009-01-01
Researchers and practitioners alike express concerns about the conceptual difficulties associated with the concepts of momentum and kinetic energy currently taught in school physics. This article presents an in-depth analysis of the treatment given to them in 44 published textbooks written for UK secondary school certificate courses. This is set…
Momentum and Kinetic Energy: Confusable Concepts in Secondary School Physics
ERIC Educational Resources Information Center
Bryce, T. G. K.; MacMillan, K.
2009-01-01
Researchers and practitioners alike express concerns about the conceptual difficulties associated with the concepts of momentum and kinetic energy currently taught in school physics. This article presents an in-depth analysis of the treatment given to them in 44 published textbooks written for UK secondary school certificate courses. This is set…
Unified Technical Concepts. Module 7: Potential and Kinetic Energy.
ERIC Educational Resources Information Center
Technical Education Research Center, Waco, TX.
This concept module on potential and kinetic energy is one of thirteen modules that provide a flexible, laboratory-based physics instructional package designed to meet the specialized needs of students in two-year, postsecondary technical schools. Each of the thirteen concept modules discusses a single physics concept and how it is applied to each…
Determination of enzyme mechanisms by radiationless energy transfer kinetics.
Lobb, R R; Auld, D S
1979-06-01
Rigorous definition of the elementary steps of an enzymatic reaction requires visualization of transient enzyme-substrate (ES) complexes. Measurement of radiationless energy transfer (RET) between enzyme tryptophan residues and a fluorescent dansyl (5-dimethylaminonaphthalene-1-sulfonyl) substrate provides a sensitive means to observe ES complexes directly. Analysis of the rate of formation and breakdown of ES complexes by RET can serve as the basis of a rapid kinetic approach to enzyme mechanisms. Both pre-steady-state and steady-state kinetics can be performed in the same RET experiment. Analysis at steady state precisely determines k(cat) and K(m) values by multiple means. Analysis at pre-steady state determines the number of intermediates, the type of reaction mechanism, and all the individual binding and rate constants. Chymotrypsin was chosen as a standard of reference for RET kinetics because extensive investigations have established both the existence of transient intermediates in the course of its catalytic process and the range of values to be expected for pertinent kinetic constants. As predicted, RET kinetics readily detects the two known intermediates in the alpha-chymotrypsincatalyzed hydrolysis of specific ester substrates. The results are both qualitatively and quantitatively in accord with data derived for this enzyme from classical kinetics. Hence, this experimental study both validates and demonstrates the theoretical advantages and potential of RET kinetics. The generality of the approach has been investigated by synthesizing a family of dansyl-labeled substrates designed to meet the specificity requirements of a number of metallo- and nonmetallo- exo- and endopeptidases. In all cases, the ES complex is observed readily at micromolar or lower concentrations of enzyme under stopped-flow conditions. The success of the RET kinetic approach on proteolytic enzymes shows its broad utility.
Systems engineering analysis of kinetic energy weapon concepts
Senglaub, M.
1996-06-01
This study examines, from a systems engineering design perspective, the potential of kinetic energy weapons being used in the role of a conventional strategic weapon. Within the Department of Energy (DOE) complex, strategic weapon experience falls predominantly in the nuclear weapons arena. The techniques developed over the years may not be the most suitable methodologies for use in a new design/development arena. For this reason a more fundamental approach was pursued with the objective of developing an information base from which design decisions might be made concerning the conventional strategic weapon system concepts. The study examined (1) a number of generic missions, (2) the effects of a number of damage mechanisms from a physics perspective, (3) measures of effectiveness (MOE`s), and (4) a design envelope for kinetic energy weapon concepts. With the base of information a cut at developing a set of high-level system requirements was made, and a number of concepts were assessed against these requirements.
Kinetic-energy density functional: Atoms and shell structure
Garcia-Gonzalez, P.; Alvarellos, J.E.; Chacon, E. |
1996-09-01
We present a nonlocal kinetic-energy functional which includes an anisotropic average of the density through a symmetrization procedure. This functional allows a better description of the nonlocal effects of the electron system. The main consequence of the symmetrization is the appearance of a clear shell structure in the atomic density profiles, obtained after the minimization of the total energy. Although previous results with some of the nonlocal kinetic functionals have given incipient structures for heavy atoms, only our functional shows a clear shell structure for most of the atoms. The atomic total energies have a good agreement with the exact calculations. Discussion of the chemical potential and the first ionization potential in atoms is included. The functional is also extended to spin-polarized systems. {copyright} {ital 1996 The American Physical Society.}
Covalent bonding: the fundamental role of the kinetic energy.
Bacskay, George B; Nordholm, Sture
2013-08-22
This work addresses the continuing disagreement between two prevalent schools of thought concerning the mechanism of covalent bonding. According to Hellmann, Ruedenberg, and Kutzelnigg, a lowering of the kinetic energy associated with electron delocalization is the key stabilization mechanism. The opposing view of Slater, Feynman, and Bader has maintained that the source of stabilization is electrostatic potential energy lowering due to electron density redistribution to binding regions between nuclei. Despite the large body of accurate quantum chemical work on a range of molecules, the debate concerning the origin of bonding continues unabated, even for H2(+), the simplest of covalently bound molecules. We therefore present here a detailed study of H2(+), including its formation, that uses a sequence of computational methods designed to reveal the relevant contributing mechanisms as well as the spatial density distributions of the kinetic and potential energy contributions. We find that the electrostatic mechanism fails to provide real insight or explanation of bonding, while the kinetic energy mechanism is sound and accurate but complex or even paradoxical to those preferring the apparent simplicity of the electrostatic model. We further argue that the underlying mechanism of bonding is in fact of dynamical character, and analyses that focus on energy do not reveal the origin of covalent bonding in full clarity.
Programmable energy landscapes for kinetic control of DNA strand displacement.
Machinek, Robert R F; Ouldridge, Thomas E; Haley, Natalie E C; Bath, Jonathan; Turberfield, Andrew J
2014-11-10
DNA is used to construct synthetic systems that sense, actuate, move and compute. The operation of many dynamic DNA devices depends on toehold-mediated strand displacement, by which one DNA strand displaces another from a duplex. Kinetic control of strand displacement is particularly important in autonomous molecular machinery and molecular computation, in which non-equilibrium systems are controlled through rates of competing processes. Here, we introduce a new method based on the creation of mismatched base pairs as kinetic barriers to strand displacement. Reaction rate constants can be tuned across three orders of magnitude by altering the position of such a defect without significantly changing the stabilities of reactants or products. By modelling reaction free-energy landscapes, we explore the mechanistic basis of this control mechanism. We also demonstrate that oxDNA, a coarse-grained model of DNA, is capable of accurately predicting and explaining the impact of mismatches on displacement kinetics.
Turbulent Kinetic Energy in the Energy Balance of a Solar Flare.
Kontar, E P; Perez, J E; Harra, L K; Kuznetsov, A A; Emslie, A G; Jeffrey, N L S; Bian, N H; Dennis, B R
2017-04-14
The energy released in solar flares derives from a reconfiguration of magnetic fields to a lower energy state, and is manifested in several forms, including bulk kinetic energy of the coronal mass ejection, acceleration of electrons and ions, and enhanced thermal energy that is ultimately radiated away across the electromagnetic spectrum from optical to x rays. Using an unprecedented set of coordinated observations, from a suite of instruments, we here report on a hitherto largely overlooked energy component-the kinetic energy associated with small-scale turbulent mass motions. We show that the spatial location of, and timing of the peak in, turbulent kinetic energy together provide persuasive evidence that turbulent energy may play a key role in the transfer of energy in solar flares. Although the kinetic energy of turbulent motions accounts, at any given time, for only ∼(0.5-1)% of the energy released, its relatively rapid (∼1-10 s) energization and dissipation causes the associated throughput of energy (i.e., power) to rival that of major components of the released energy in solar flares, and thus presumably in other astrophysical acceleration sites.
Effects of directed and kinetic energy weapons on spacecraft
Fraas, A P
1986-12-01
The characteristics of the various directed energy beams are reviewed, and their damaging effects on typical materials are examined for a wide range of energy pulse intensities and durations. Representative cases are surveyed, and charts are presented to indicate regions in which damage to spacecraft structures, particularly radiators for power plants, would be likely. The effects of kinetic energy weapons, such as bird-shot, are similarly examined. The charts are then applied to evaluate the effectiveness of various measures designed to reduce the vulnerability of spacecraft components, particularly nuclear electric power plants.
Possible explanation of the atmospheric kinetic and potential energy spectra.
Vallgren, Andreas; Deusebio, Enrico; Lindborg, Erik
2011-12-23
We hypothesize that the observed wave number spectra of kinetic and potential energy in the atmosphere can be explained by assuming that there are two related cascade processes emanating from the same large-scale energy source, a downscale cascade of potential enstrophy, giving rise to the k(-3) spectrum at synoptic scales and a downscale energy cascade giving rise to the k(-5/3) spectrum at mesoscales. The amount of energy which is going into the downscale energy cascade is determined by the rate of system rotation, with negligible energy going downscale in the limit of very fast rotation. We present a set of simulations of a system with strong rotation and stratification, supporting these hypotheses and showing good agreement with observations.
Reaction Path Optimization with Holonomic Constraints and Kinetic Energy Potentials
Brokaw, Jason B.; Haas, Kevin R.; Chu, Jhih-wei
2009-08-11
Two methods are developed to enhance the stability, efficiency, and robustness of reaction path optimization using a chain of replicas. First, distances between replicas are kept equal during path optimization via holonomic constraints. Finding a reaction path is, thus, transformed into a constrained optimization problem. This approach avoids force projections for finding minimum energy paths (MEPs), and fast-converging schemes such as quasi-Newton methods can be readily applied. Second, we define a new objective function - the total Hamiltonian - for reaction path optimization, by combining the kinetic energy potential of each replica with its potential energy function. Minimizing the total Hamiltonian of a chain determines a minimum Hamiltonian path (MHP). If the distances between replicas are kept equal and a consistent force constant is used, then the kinetic energy potentials of all replicas have the same value. The MHP in this case is the most probable isokinetic path. Our results indicate that low-temperature kinetic energy potentials (<5 K) can be used to prevent the development of kinks during path optimization and can significantly reduce the required steps of minimization by 2-3 times without causing noticeable differences between a MHP and MEP. These methods are applied to three test cases, the C₇eq-to-Cax isomerization of an alanine dipeptide, the ⁴C₁- to-¹C₄ transition of an α-D-glucopyranose, and the helix-to-sheet transition of a GNNQQNY heptapeptide. By applying the methods developed in this work, convergence of reaction path optimization can be achieved for these complex transitions, involving full atomic details and a large number of replicas (>100). For the case of helix-to-sheet transition, we identify pathways whose energy barriers are consistent with experimental measurements. Further, we develop a method based on the work energy theorem to quantify the accuracy of reaction paths and to determine whether the atoms used to define a
Reaction Path Optimization with Holonomic Constraints and Kinetic Energy Potentials.
Brokaw, Jason B; Haas, Kevin R; Chu, Jhih-Wei
2009-08-11
Two methods are developed to enhance the stability, efficiency, and robustness of reaction path optimization using a chain of replicas. First, distances between replicas are kept equal during path optimization via holonomic constraints. Finding a reaction path is, thus, transformed into a constrained optimization problem. This approach avoids force projections for finding minimum energy paths (MEPs), and fast-converging schemes such as quasi-Newton methods can be readily applied. Second, we define a new objective function - the total Hamiltonian - for reaction path optimization, by combining the kinetic energy potential of each replica with its potential energy function. Minimizing the total Hamiltonian of a chain determines a minimum Hamiltonian path (MHP). If the distances between replicas are kept equal and a consistent force constant is used, then the kinetic energy potentials of all replicas have the same value. The MHP in this case is the most probable isokinetic path. Our results indicate that low-temperature kinetic energy potentials (<5 K) can be used to prevent the development of kinks during path optimization and can significantly reduce the required steps of minimization by 2-3 times without causing noticeable differences between a MHP and MEP. These methods are applied to three test cases, the C7eq-to-Cax isomerization of an alanine dipeptide, the (4)C1-to-(1)C4 transition of an α-d-glucopyranose, and the helix-to-sheet transition of a GNNQQNY heptapeptide. By applying the methods developed in this work, convergence of reaction path optimization can be achieved for these complex transitions, involving full atomic details and a large number of replicas (>100). For the case of helix-to-sheet transition, we identify pathways whose energy barriers are consistent with experimental measurements. Further, we develop a method based on the work energy theorem to quantify the accuracy of reaction paths and to determine whether the atoms used to define a path
Plasmadynamics and ionization kinetics of thermionic energy conversion
Lawless, J.L. Jr.; Lam, S.H.
1982-02-01
To reduce the plasma arc-drop, thermionic energy conversion is studied with both analytical and numerical tools. Simplifications are made in both the plasmadynamic and ionization-recombination theories. These are applied to a scheme proposed presently using laser irradiation to enhance the ionization kinetics of the thermionic plasma and thereby reduce the arc-drop. It is also predicted that it is possible to generate the required laser light from a thermionic-type cesium plasma. The analysis takes advantage of theoretical simplifications derived for the ionization-recombination kinetics. It is shown that large laser ionization enhancements can occur and that collisional cesium recombination lasing is expected. To complement the kinetic theory, a numerical method is developed to solve the thermionic plasma dynamics. To combine the analysis of ionization-recombination kinetics with the plasma dynamics of thermionic conversion, a finite difference computer program is constructed. It is capable of solving for both unsteady and steady thermionic converter behavior including possible laser ionization enhancement or atomic recombination lasing. A proposal to improve thermionic converter performance using laser radiation is considered. In this proposed scheme, laser radiation impinging on a thermionic plasma enhances the ionization process thereby raising the plasma density and reducing the plasma arc-drop. A source for such radiation may possibly be a cesium recombination laser operating in a different thermionic converter. The possibility of this being an energy efficient process is discussed. (WHK)
Bicarbonate kinetics and predicted energy expenditure in critically ill children.
Sy, Jama; Gourishankar, Anand; Gordon, William E; Griffin, Debra; Zurakowski, David; Roth, Rachel M; Coss-Bu, Jorge; Jefferson, Larry; Heird, William; Castillo, Leticia
2008-08-01
To determine nutrient requirements by the carbon oxidation techniques, it is necessary to know the fraction of carbon dioxide produced during the oxidative process but not excreted. This fraction has not been described in critically ill children. By measuring the dilution of (13)C infused by metabolically produced carbon dioxide, the rates of carbon dioxide appearance can be estimated. Energy expenditure can be determined by bicarbonate dilution kinetics if the energy equivalents of carbon dioxide (food quotient) from the diet ingested are known. We conducted a 6-h, primed, continuous tracer infusion of NaH(13)CO(3) in critically ill children fed parenterally or enterally or receiving only glucose and electrolytes, to determine bicarbonate fractional recovery, bicarbonate rates of appearance, and energy expenditure. Thirty-one critically ill children aged 1 mo-20 y who were admitted to a pediatric intensive care unit at a tertiary-care center were studied. Patients were stratified by age, BMI, and severity score (PRISM III). Fractional bicarbonate recovery was 0.69, 0.70, and 0.63, respectively, for the parenterally fed, enterally fed, and glucose-electrolytes groups, and it correlated with the severity of disease in the parenteral (P < 0.01) and glucose-electrolytes (P < 0.05) groups. Rates of appearance varied between 0.17 and 0.19 micromol . kg(-1) . h(-1) With these data and estimates of the energy equivalents of carbon dioxide (a surrogate for respiratory quotient), energy expenditure was determined. The 2001 World Health Organization and Schofield predictive equations overestimated and underestimated, respectively, energy requirements compared with those obtained by bicarbonate dilution kinetics. Bicarbonate kinetics allows accurate determination of energy needs in critically ill children.
Kinetic energy budgets during the life cycle of intense convective activity
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Scoggins, J. R.
1978-01-01
Synoptic-scale data at three- and six-hour intervals are employed to study the relationship between changing kinetic energy variables and the life cycles of two severe squall lines. The kinetic energy budgets indicate a high degree of kinetic energy generation, especially pronounced near the jet-stream level. Energy losses in the storm environment are due to the transfer of kinetic energy from grid to subgrid scales of motion; large-scale upward vertical motion carries aloft the kinetic energy generated by storm activity at lower levels. In general, the time of maximum storm intensity is also the time of maximum energy conversion and transport.
Casimir rack and pinion as a miniaturized kinetic energy harvester.
Miri, MirFaez; Etesami, Zahra
2016-08-01
We study a nanoscale machine composed of a rack and a pinion with no contact, but intermeshed via the lateral Casimir force. We adopt a simple model for the random velocity of the rack subject to external random forces, namely, a dichotomous noise with zero mean value. We show that the pinion, even when it experiences random thermal torque, can do work against a load. The device thus converts the kinetic energy of the random motions of the rack into useful work.
A study of the kinetic energy generation with general circulation models
NASA Technical Reports Server (NTRS)
Chen, T.-C.; Lee, Y.-H.
1983-01-01
The history data of winter simulation by the GLAS climate model and the NCAR community climate model are used to examine the generation of atmospheric kinetic energy. The contrast between the geographic distributions of the generation of kinetic energy and divergence of kinetic energy flux shows that kinetic energy is generated in the upstream side of jets, transported to the downstream side and destroyed there. The contributions from the time-mean and transient modes to the counterbalance between generation of kinetic energy and divergence of kinetic energy flux are also investigated. It is observed that the kinetic energy generated by the time-mean mode is essentially redistributed by the time-mean flow, while that generated by the transient flow is mainly responsible for the maintenance of the kinetic energy of the entire atmospheric flow.
A study of the kinetic energy generation with general circulation models
NASA Technical Reports Server (NTRS)
Chen, T.-C.; Lee, Y.-H.
1983-01-01
The history data of winter simulation by the GLAS climate model and the NCAR community climate model are used to examine the generation of atmospheric kinetic energy. The contrast between the geographic distributions of the generation of kinetic energy and divergence of kinetic energy flux shows that kinetic energy is generated in the upstream side of jets, transported to the downstream side and destroyed there. The contributions from the time-mean and transient modes to the counterbalance between generation of kinetic energy and divergence of kinetic energy flux are also investigated. It is observed that the kinetic energy generated by the time-mean mode is essentially redistributed by the time-mean flow, while that generated by the transient flow is mainly responsible for the maintenance of the kinetic energy of the entire atmospheric flow.
Maximum kinetic energy considerations in proton stereotactic radiosurgery.
Sengbusch, Evan R; Mackie, Thomas R
2011-04-12
The purpose of this study was to determine the maximum proton kinetic energy required to treat a given percentage of patients eligible for stereotactic radiosurgery (SRS) with coplanar arc-based proton therapy, contingent upon the number and location of gantry angles used. Treatment plans from 100 consecutive patients treated with SRS at the University of Wisconsin Carbone Cancer Center between June of 2007 and March of 2010 were analyzed. For each target volume within each patient, in-house software was used to place proton pencil beam spots over the distal surface of the target volume from 51 equally-spaced gantry angles of up to 360°. For each beam spot, the radiological path length from the surface of the patient to the distal boundary of the target was then calculated along a ray from the gantry location to the location of the beam spot. This data was used to generate a maximum proton energy requirement for each patient as a function of the arc length that would be spanned by the gantry angles used in a given treatment. If only a single treatment angle is required, 100% of the patients included in the study could be treated by a proton beam with a maximum kinetic energy of 118 MeV. As the length of the treatment arc is increased to 90°, 180°, 270°, and 360°, the maximum energy requirement increases to 127, 145, 156, and 179 MeV, respectively. A very high percentage of SRS patients could be treated at relatively low proton energies if the gantry angles used in the treatment plan do not span a large treatment arc. Maximum proton kinetic energy requirements increase linearly with size of the treatment arc.
Enhanced propagation of rainfall kinetic energy in the UK
NASA Astrophysics Data System (ADS)
Diodato, Nazzareno; Bellocchi, Gianni
2017-08-01
A gridded 0.25° reconstruction of rainfall kinetic energy (RKE) over the UK, on the basis of pluviometric observations and reanalysis back to 1765, shows that autumn RKE doubled in 1991-2013 (˜2 MJ m-2) compared to 1948-1990 (˜1 MJ m-2). A shift eastward is underway, which includes southern and northern portions of the country. Analyzing the long-running England and Wales precipitation series, we conclude that it is likely that increased precipitation amounts associated with more frequent convective storms created conditions for higher energy events.
Kinetics of Reactions of Monomeric Nitrosomethane Induced by Flash Photolysis.
ERIC Educational Resources Information Center
Kozubek, H.; And Others
1984-01-01
Describes an experiment in which the kinetics of dimerization of nitrosamine induced by a flash of light is measured. The experiment can be performed with a commercial ultraviolet-VIS spetrophotometer with easy to make modifications. The experiment demonstrates a flash photolysis system not always available in university chemistry laboratories.…
NASA Astrophysics Data System (ADS)
Meneveau, Charles
2015-11-01
A topic that elicited the interest of John Lumley is pressure transport in turbulence. In 1978 (JL, in Advances in Applied Mechanics, pages 123-176) he showed that pressure transport likely acts in the opposite direction to the spatial flux of kinetic energy due to triple velocity correlations. Here we examine a flow in which the interplay of turbulent decay and spatial transport is particularly relevant. Specifically, using a specially designed active grid and screens placed in the Corrsin wind tunnel, such a flow is realized. Data are acquired using X-wire thermal anemometry at different spanwise and downstream locations. In order to resolve the dissipation rate accurately, measurements are also acquired using the NSTAP probe developed and manufactured by Princeton researchers and kindly provided to us (M. Hultmark, Y. Fan, L. Smits). The results show power-law decay with downstream distance, with a decay exponent that becomes larger in the high kinetic energy side of the flow. Measurements of the dissipation enable us to obtain the spanwise gradient of the spatial flux. One possible explanation for the observations is upgrading transport of kinetic energy due to pressure-velocity correlations, although its magnitude required to close the budget appears very large. Absence of simultaneous pressure velocity measurement preclude us to fully elucidate the observed trends. In collaboration with Adrien Thormann, Johns Hopkins University. Financial support: National Science Foundation.
Kinetic Modeling of Laser-Induced Fusion
2007-09-01
Thermal neutrons are of considerable interest to the Department of Defense and for commercial applications. Unlike high- energy photons, neutrons easily...develop a compact generator for thermal neutrons with large enough flux. The limited availability of radio-isotopes, combined with the relatively...Deuterium-Tritium (D-T) fusion, which generates Alpha particles and fast neutrons . In these sources, Deuterium ions are accelerated to about 130 keV and hit
Kinetic Modeling of Laser Induced Fusion
2007-07-01
distribution unlimited (PA #07298A). 13. SUPPLEMENTARY NOTES For presentation at AFRL and AFOSR. 14. ABSTRACT Thermal neutrons are of...considerable interest to the Department of Defense and for commercial applications. Unlike high-energy photons, neutrons easily penetrate high density...for thermal neutrons with large enough flux. The limited availability of radio-isotopes, combined with the relatively short half-life, safety
Violation of an f -sum rule with generalized kinetic energy
NASA Astrophysics Data System (ADS)
Limtragool, Kridsanaphong; Phillips, Philip W.
2017-05-01
Motivated by the normal state of the cuprates in which the integrated spectral weight of the optical conductivity or optical sum increases faster than a linear function of the particle density, we derive an f -sum rule for a system in which the kinetic-energy operator in the Hamiltonian is a general function of the momentum squared. Such a kinetic energy arises in scale invariant theories and can be derived within the context of holography. Our derivation of the f -sum rule is based on the gauge couplings of a nonlocal Lagrangian in which the kinetic operator is a fractional Laplacian of order α . We find that the f -sum rule in this case deviates from the standard linear dependence on the particle density. We find two regimes. At high temperatures and low densities, the optical sum is proportional to n Tα/-1 α where T is the temperature. At low temperatures and high densities, the optical sum is proportional to n1 +2/(α -1 ) d with d being the number of spatial dimensions. The result in the low-temperature and high-density limit, when α <1 , can be used to qualitatively explain the behavior of the effective number of charge carriers in the cuprates at various doping concentrations.
Biomineralization mechanisms: a kinetics and interfacial energy approach
NASA Astrophysics Data System (ADS)
Nancollas, George H.; Wu, Wenju
2000-04-01
The calcium phosphates and oxalates are among the most frequently encountered biomineral phases and numerous kinetics studies have been made of their crystallization and dissolution in supersaturated and undersaturated solutions, respectively. These have focused mainly on parameters such as solution composition, ionic strength, pH, temperature, and solid surface characteristics. There is considerable interest in extending such studies to solutions more closely simulating the biological milieu. The constant composition method is especially useful for investigating the mechanisms of these reactions, and in the present work, the interfacial tensions between water and each of these surfaces have been calculated from measured contact angles using surface tension component theory. Values for the calcium phosphate phases such as dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP), hydroxyapatite (HAP), and fluorapatite (FAP) may be compared with data calculated from dissolution kinetics experiments invoking different reaction mechanisms. Agreement between the directly measured interfacial energies and those calculated from the kinetics experiments provides valuable corroborative information about individual growth and dissolution mechanisms. For the calcium phosphates, the much smaller interfacial tensions of OCP and DCPD in contact with water as compared with those of HAP and FAP support the suggestion that the former phases are precursors in HAP and FAP biomineralization. The ability of a surface to nucleate mineral phases is closely related to the magnitude of the interfacial energies. Constant composition studies have also shown that HAP is an effective nucleator of calcium oxalate monohydrate, both of which are frequently observed in renal stones.
Budgets of divergent and rotational kinetic energy during two periods of intense convection
NASA Technical Reports Server (NTRS)
Buechler, D. E.; Fuelberg, H. E.
1986-01-01
The derivations of the energy budget equations for divergent and rotational components of kinetic energy are provided. The intense convection periods studied are: (1) synoptic scale data of 3 or 6 hour intervals and (2) mesoalphascale data every 3 hours. Composite energies and averaged budgets for the periods are presented; the effects of random data errors on derived energy parameters is investigated. The divergent kinetic energy and rotational kinetic energy budgets are compared; good correlation of the data is observed. The kinetic energies and budget terms increase with convective development; however, the conversion of the divergent and rotational energies are opposite.
Spectral Energy Transfer and Dissipation of Magnetic Energy from Fluid to Kinetic Scales
Bowers, K.; Li, H.
2007-01-19
We investigate the magnetic energy transfer from the fluid to kinetic scales and dissipation processes using three-dimensional fully kinetic particle-in-cell plasma simulations. The nonlinear evolution of a sheet pinch is studied where we show that it exhibits both fluid scale global relaxation and kinetic scale collisionless reconnection at multiple resonant surfaces. The interactions among collisionless tearing modes destroy the original flux surfaces and produce stochastic fields, along with generating sheets and filaments of intensified currents. In addition, the magnetic energy is transferred from the original shear length scale both to the large scales due to the global relaxation and to the smaller, kinetic scales for dissipation. The dissipation is dominated by the thermal or pressure effect in the generalized Ohm's law, and electrons are preferentially accelerated.
Nowcasting of kinetic energy of hail precipitation using radar
NASA Astrophysics Data System (ADS)
Sánchez, J. L.; López, L.; García-Ortega, E.; Gil, B.
2013-04-01
The detection of hail precipitation generated by a storm is a complicated task due to the limited spatial extension and the space-time irregularity of impacts generated on the ground. Some of the most extensive methods to create climatology of these impacts are observer networks or hailpad networks. Both methods are affected by numerous inconveniences, overall when it is necessary to work with an extensive area, in which it is necessary to maintain an operating network that has numerous maintenance costs. In this sense, there are numerous works done that have developed different models with the objective of detecting hail precipitation using meteorological radar. Some of these methods use discriminant statistic techniques that, through the combination of different radar parameters, can achieve very satisfactory results. On the other hand, it would be very interesting to know not only the probability of hail, but also some of the characteristics of the hailstones precipitated, such as the number or their kinetic energy, since these parameters are directly related to the damage generated in infrastructures and/or crops. The estimation of kinetic energy of hail precipitation using meteorological radar has caught the interest of some authors. In our case, we used the databases obtained by hailpad networks and the databases of C-band and S-Band radar to build an algorithm to estimate the vertical component of kinetic energy produced by a hail precipitation. In order to carry out this study, data on hail was gathered and analyzed from the hailpad networks in the province of Zaragoza (in the north-east of Spain) and the province of Mendoza (in Argentina, close to the Andes range on the border with Chile). These are two geographically distant regions, but which share a common characteristic: a high frequency of storms with hail precipitation, mainly during the summer months (Sánchez et al., 2009a). In order to compile the database, we have established two categories of
Font, J.; Torrent, J.; Ribó, M.; Laurents, D. V.; Balny, C.; Vilanova, M.; Lange, R.
2006-01-01
Pressure-jump (p-jump)-induced relaxation kinetics was used to explore the energy landscape of protein folding/unfolding of Y115W, a fluorescent variant of ribonuclease A. Pressure-jumps of 40 MPa amplitude (5 ms dead-time) were conducted both to higher (unfolding) and to lower (folding) pressure, in the range from 100 to 500 MPa, between 30 and 50°C. Significant deviations from the expected symmetrical protein relaxation kinetics were observed. Whereas downward p-jumps resulted always in single exponential kinetics, the kinetics induced by upward p-jumps were biphasic in the low pressure range and monophasic at higher pressures. The relative amplitude of the slow phase decreased as a function of both pressure and temperature. At 50°C, only the fast phase remained. These results can be interpreted within the framework of a two-dimensional energy surface containing a pressure- and temperature-dependent barrier between two unfolded states differing in the isomeric state of the Asn-113–Pro-114 bond. Analysis of the activation volume of the fast kinetic phase revealed a temperature-dependent shift of the unfolding transition state to a larger volume. The observed compensation of this effect by glycerol offers an explanation for its protein stabilizing effect. PMID:16798802
Momentum and kinetic energy before the tackle in rugby union.
Hendricks, Sharief; Karpul, David; Lambert, Mike
2014-09-01
Understanding the physical demands of a tackle in match situations is important for safe and effective training, developing equipment and research. Physical components such as momentum and kinetic energy, and it relationship to tackle outcome is not known. The aim of this study was to compare momenta between ball-carrier and tackler, level of play (elite, university and junior) and position (forwards vs. backs), and describe the relationship between ball-carrier and tackler mass, velocity and momentum and the tackle outcome. Also, report on the ball-carrier and tackler kinetic energy before contact and the estimated magnitude of impact (energy distributed between ball-carrier and tackler upon contact). Velocity over 0.5 seconds before contact was determined using a 2-dimensional scaled version of the field generated from a computer alogorithm. Body masses of players were obtained from their player profiles. Momentum and kinetic energy were subsequently calculated for 60 tackle events. Ball-carriers were heavier than the tacklers (ball-carrier 100 ± 14 kg vs. tackler 93 ± 11 kg, d = 0.52, p = 0.0041, n = 60). Ball-carriers as forwards had a significantly higher momentum than backs (forwards 563 ± 226 Kg(.)m(.)s(-1) n = 31 vs. backs 438 ± 135 Kg(.)m(.)s(-1), d = 0.63, p = 0.0012, n = 29). Tacklers dominated 57% of tackles and ball-carriers dominated 43% of tackles. Despite the ball-carrier having a mass advantage before contact more frequently than the tackler, momentum advantage and tackle dominance between the ball-carrier and tackler was proportionally similar. These findings may reflect a characteristic of the modern game of rugby where efficiently heavier players (particularly forwards) are tactically predetermined to carry the ball in contact. Key PointsFirst study to quantify momentum, kinetic energy, and magnitude of impact in rugby tackles across different levels in matches without a device attached to a player.Physical components alone, of either ball
Momentum and Kinetic Energy Before the Tackle in Rugby Union
Hendricks, Sharief; Karpul, David; Lambert, Mike
2014-01-01
Understanding the physical demands of a tackle in match situations is important for safe and effective training, developing equipment and research. Physical components such as momentum and kinetic energy, and it relationship to tackle outcome is not known. The aim of this study was to compare momenta between ball-carrier and tackler, level of play (elite, university and junior) and position (forwards vs. backs), and describe the relationship between ball-carrier and tackler mass, velocity and momentum and the tackle outcome. Also, report on the ball-carrier and tackler kinetic energy before contact and the estimated magnitude of impact (energy distributed between ball-carrier and tackler upon contact). Velocity over 0.5 seconds before contact was determined using a 2-dimensional scaled version of the field generated from a computer alogorithm. Body masses of players were obtained from their player profiles. Momentum and kinetic energy were subsequently calculated for 60 tackle events. Ball-carriers were heavier than the tacklers (ball-carrier 100 ± 14 kg vs. tackler 93 ± 11 kg, d = 0.52, p = 0.0041, n = 60). Ball-carriers as forwards had a significantly higher momentum than backs (forwards 563 ± 226 Kg.m.s-1 n = 31 vs. backs 438 ± 135 Kg.m.s-1, d = 0.63, p = 0.0012, n = 29). Tacklers dominated 57% of tackles and ball-carriers dominated 43% of tackles. Despite the ball-carrier having a mass advantage before contact more frequently than the tackler, momentum advantage and tackle dominance between the ball-carrier and tackler was proportionally similar. These findings may reflect a characteristic of the modern game of rugby where efficiently heavier players (particularly forwards) are tactically predetermined to carry the ball in contact. Key Points First study to quantify momentum, kinetic energy, and magnitude of impact in rugby tackles across different levels in matches without a device attached to a player. Physical components alone, of either ball-carrier or
Lu, San; Lu, Quanming; Huang, Can; Wang, Shui
2013-06-15
By performing two-dimensional particle-in-cell simulations, we investigate the transfer between electron bulk kinetic and electron thermal energy in collisionless magnetic reconnection. In the vicinity of the X line, the electron bulk kinetic energy density is much larger than the electron thermal energy density. The evolution of the electron bulk kinetic energy is mainly determined by the work done by the electric field force and electron pressure gradient force. The work done by the electron gradient pressure force in the vicinity of the X line is changed to the electron enthalpy flux. In the magnetic island, the electron enthalpy flux is transferred to the electron thermal energy due to the compressibility of the plasma in the magnetic island. The compression of the plasma in the magnetic island is the consequence of the electromagnetic force acting on the plasma as the magnetic field lines release their tension after being reconnected. Therefore, we can observe that in the magnetic island the electron thermal energy density is much larger than the electron bulk kinetic energy density.
Energy cascade down to kinetic scales and the role of pressure tensor in heating of kinetic plasma
NASA Astrophysics Data System (ADS)
Yang, Y.; Matthaeus, W. H.; Parashar, T.; Wan, M.
2016-12-01
The classical energy cascade theory suggests that energy is transferred from large to small scales at a constant rate and nonlinear interactions occur predominately between comparable scales. This scenario is of great importance in explaining the heating of corona and solar wind. One can envision that energy residing in large-scale fluctuations is transported to smaller scales where dissipation occurs and finally drives kinetic processes that absorb the energy flux and energize charged particles. The energy cascade well above kinetic scales has been studied, while little is known about that when getting close to ion kinetic scales. When filtering the Vlasov equation, we can introduce several energy transfer functions across scales and filtered energy equations resembling to those in MHD. We propose to use kinetic plasma simulations and investigate how the characteristics of energy transfer vary going from MHD to kinetic scales. It has been shown that in compressible MHD turbulence [1] , apart from dissipation, the pressure dilation, p ∇ \\cdot {u}, can trigger an alternative channel of the conversion between kinetic and internal energy. We will address the analogous roles of the (tensor) pressure dilation, which now reads ( {P} \\cdot ∇ ) \\cdot {u} in collisionless plasma. We study, for example, effects of anisotropic and isotropic pressure, and of the diagonal and off-diagonal pressure tensor, and related influences on dissipation and heating. [1] Y. Yang et al, Phys. Rev. E, 93, 061102(R) (2016)
Magnetically confined kinetic-energy storage ring: A new fundamental energy-storage concept
NASA Astrophysics Data System (ADS)
Hull, J. R.; Schertz, W. W.
1985-07-01
A new, fundamental type of energy storage device which has the potential for low cost diurnal storage of electrical energy is introduced. The magnetically confined kinetic energy storage ring (MCKESR) stores kinetic energy as mass circulated at high velocity around a circular loop. The constraining force necessary to keep the circulating mass (essentially a ring) from flying apart is provided by radial, inwardly directed forces exerted along the parameter of the loop by magnetic fields. The magnets and ring are contained in a tunnel, which may be buried in the ground. Levitational support against gravity is also provided by magnetic fields. Electrical energy insertion or extraction is similar to that for a synchronous motor/generator. Major advantages of the MCKESR concept are that large devices seem feasible and that costs are inversely related to size. The use of superconducting magnets should result in a very high energy recovery efficiency.
A Detailed Level Kinetics Model of NO Vibrational Energy Distributions
NASA Technical Reports Server (NTRS)
Sharma, Surendra P.; Gilmore, John; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Several contemporary problems have pointed to the desirability of a detailed level kinetics approach to modeling the distribution of vibrational energy in NO. Such a model is necessary when vibrational redistribution reactions are insufficient to maintain a Boltzmann distribution over the vibrational energy states. Recent calculations of the rate constant for the first reaction of the Zeldovich mechanism (N2 + O (goes to) NO + N) have suggested that the product NO is formed in high vibrational states. In shock layer flowfields, the product NO molecules may experience an insufficient number of collisions to establish a Boltzmann distribution over vibrational states, thus necessitating a level kinetics model. In other flows, such as expansions of high temperature air, fast, near-resonance vibrational energy exchanges with N2 and O2 may also require a level specific model for NO because of the relative rates of vibrational exchange and redistribution. The proposed report will integrate computational and experimental components to construct such a model for the NO molecule.
A Detailed Level Kinetics Model of NO Vibrational Energy Distributions
NASA Technical Reports Server (NTRS)
Sharma, Surendra P.; Gilmore, John; Cavolowsky, John A. (Technical Monitor)
1996-01-01
Several contemporary problems have pointed to the desirability of a detailed level kinetics approach to modeling the distribution of vibrational energy in NO. Such a model is necessary when vibrational redistribution reactions are insufficient to maintain a Boltzmann distribution over the vibrational energy states. Recent calculations of the rate constant for the first reaction of the Zeldovich mechanism (N2 + O (goes to) NO + N) have suggested that the product NO is formed in high vibrational states. In shock layer flowfields, the product NO molecules may experience an insufficient number of collisions to establish a Boltzmann distribution over vibrational states, thus necessitating a level kinetics model. In other flows, such as expansions of high temperature air, fast, near-resonance vibrational energy exchanges with N2 and O2 may also require a level specific model for NO because of the relative rates of vibrational exchange and redistribution. The proposed report will integrate computational and experimental components to construct such a model for the NO molecule.
Conversion of magnetic field energy into kinetic energy in the solar wind
NASA Technical Reports Server (NTRS)
Whang, Y. C.
1972-01-01
The outflow of the solar magnetic field energy (the radial component of the Poynting vector) per steradian is inversely proportional to the solar wind velocity. It is a decreasing function of the heliocentric distance. When the magnetic field effect is included in the one-fluid model of the solar wind, the transformation of magnetic field energy into kinetic energy during the expansion process increases the solar wind velocity at 1 AU by 17 percent.
Mass yields and kinetic energy of fragments from fission of highly-excited nuclei with A≲220
NASA Astrophysics Data System (ADS)
Denisov, V. Yu.; Margitych, T. O.; Sedykh, I. Yu.
2017-02-01
It is shown that the potential energy surface of the two separated fragments has the saddle point, which takes place at small distance between the surfaces of well-deformed fragments. The height of this two-body saddle point is larger than the height of one-body fission barrier for nuclei with A ≲ 220. The mass yields of the fission fragments, which are appearing at the fission of nuclei with A ≲ 220, are related to the number of states of the two-fragment systems at the two-body saddle points. The characteristics of kinetic energy of fragments are described by using the trajectory motion equations with the dissipation terms. The Gaussian distribution of the final kinetic energy around the classical value of this energy induced by the stochastic fluctuations is taken into account at an evaluation of the total kinetic energy distributions of the fission fragments.
Modeling the turbulent kinetic energy equation for compressible, homogeneous turbulence
NASA Technical Reports Server (NTRS)
Aupoix, B.; Blaisdell, G. A.; Reynolds, William C.; Zeman, Otto
1990-01-01
The turbulent kinetic energy transport equation, which is the basis of turbulence models, is investigated for homogeneous, compressible turbulence using direct numerical simulations performed at CTR. It is shown that the partition between dilatational and solenoidal modes is very sensitive to initial conditions for isotropic decaying turbulence but not for sheared flows. The importance of the dilatational dissipation and of the pressure-dilatation term is evidenced from simulations and a transport equation is proposed to evaluate the pressure-dilatation term evolution. This transport equation seems to work well for sheared flows but does not account for initial condition sensitivity in isotropic decay. An improved model is proposed.
Zhao, Linjie; Sun, Tanlin; Pei, Jianfeng; Ouyang, Qi
2015-07-28
It has been a consensus in cancer research that cancer is a disease caused primarily by genomic alterations, especially somatic mutations. However, the mechanism of mutation-induced oncogenesis is not fully understood. Here, we used the mitochondrial apoptotic pathway as a case study and performed a systematic analysis of integrating pathway dynamics with protein interaction kinetics to quantitatively investigate the causal molecular mechanism of mutation-induced oncogenesis. A mathematical model of the regulatory network was constructed to establish the functional role of dynamic bifurcation in the apoptotic process. The oncogenic mutation enrichment of each of the protein functional domains involved was found strongly correlated with the parameter sensitivity of the bifurcation point. We further dissected the causal mechanism underlying this correlation by evaluating the mutational influence on protein interaction kinetics using molecular dynamics simulation. We analyzed 29 matched mutant-wild-type and 16 matched SNP--wild-type protein systems. We found that the binding kinetics changes reflected by the changes of free energy changes induced by protein interaction mutations, which induce variations in the sensitive parameters of the bifurcation point, were a major cause of apoptosis pathway dysfunction, and mutations involved in sensitive interaction domains show high oncogenic potential. Our analysis provided a molecular basis for connecting protein mutations, protein interaction kinetics, network dynamics properties, and physiological function of a regulatory network. These insights provide a framework for coupling mutation genotype to tumorigenesis phenotype and help elucidate the logic of cancer initiation.
Zhao, Linjie; Sun, Tanlin; Pei, Jianfeng; Ouyang, Qi
2015-01-01
It has been a consensus in cancer research that cancer is a disease caused primarily by genomic alterations, especially somatic mutations. However, the mechanism of mutation-induced oncogenesis is not fully understood. Here, we used the mitochondrial apoptotic pathway as a case study and performed a systematic analysis of integrating pathway dynamics with protein interaction kinetics to quantitatively investigate the causal molecular mechanism of mutation-induced oncogenesis. A mathematical model of the regulatory network was constructed to establish the functional role of dynamic bifurcation in the apoptotic process. The oncogenic mutation enrichment of each of the protein functional domains involved was found strongly correlated with the parameter sensitivity of the bifurcation point. We further dissected the causal mechanism underlying this correlation by evaluating the mutational influence on protein interaction kinetics using molecular dynamics simulation. We analyzed 29 matched mutant–wild-type and 16 matched SNP—wild-type protein systems. We found that the binding kinetics changes reflected by the changes of free energy changes induced by protein interaction mutations, which induce variations in the sensitive parameters of the bifurcation point, were a major cause of apoptosis pathway dysfunction, and mutations involved in sensitive interaction domains show high oncogenic potential. Our analysis provided a molecular basis for connecting protein mutations, protein interaction kinetics, network dynamics properties, and physiological function of a regulatory network. These insights provide a framework for coupling mutation genotype to tumorigenesis phenotype and help elucidate the logic of cancer initiation. PMID:26170328
Kinetic energy management in road traffic injury prevention: a call for action
Khorasani-Zavareh, Davoud; Bigdeli, Maryam; Saadat, Soheil; Mohammadi, Reza
2015-01-01
Abstract: By virtue of their variability, mass and speed have important roles in transferring energies during a crash incidence (kinetic energy). The sum of kinetic energy is important in determining an injury severity and that is equal to one half of the vehicle mass multiplied by the square of the vehicle speed. To meet the Vision Zero policy (a traffic safety policy) prevention activities should be focused on vehicle speed management. Understanding the role of kinetic energy will help to develop measures to reduce the generation, distribution, and effects of this energy during a road traffic crash. Road traffic injury preventive activities necessitate Kinetic energy management to improve road user safety. PMID:24284810
On a Broken Formal Symmetry between Kinetic and Gravitational Energy
NASA Astrophysics Data System (ADS)
Nikkhah Shirazi, Armin
2011-03-01
Historically, the discovery of symmetries has played an important role in the progress of our fundamental understanding of nature. This paper will demonstrate that there exists in Newtonian theory in a spherical gravitational field a formal symmetry between the kinetic (KE) and gravitational potential energy (GPE) of a test mass. Put differently, there exists a way of expressing GPE such that the form of the mathematical expression remains invariant under an interchange of KE and GPE. When extended to relativity by a suitable assumption, it leads to a framework that bridges the general relativistic and Newtonian conceptions of gravitational energy, even though the symmetry is broken except in the infinitesimal limit. Recognizing this symmetry at infinitesimal scales makes it possible to write a relativistic equation of an individual graviton, the properties of which under under one interpretation may be unexpected.
Spectral Kinetic Energy Transfer Through a Premixed Flame Brush
NASA Astrophysics Data System (ADS)
Towery, Colin A. Z.; Poludnenko, Alexei Y.; Hamlington, Peter E.
2014-11-01
Turbulence-flame interactions are of fundamental importance for understanding and modeling premixed turbulent reacting flows. These interactions can result in nonlinear feedback leading to large changes in both the turbulence and flame. Recent computational studies have indicated, however, that not all scales of turbulent motion are affected equally. Small-scale motions appear to be suppressed while larger-scale motions are unaffected or even enhanced. In order to determine the scale-dependence of turbulence-flame interactions, direct numerical simulations of statistically planar, premixed flames have been performed and analyzed. Two-dimensional kinetic energy spectra, conditioned on the planar-averaged fuel mass-fraction, are measured through the flame brush and compared to both compressible and incompressible non-reacting flow spectra. Changes in the spectra with respect to fuel mass-fraction are then connected to the dynamics of the kinetic energy spectrum transport equation. Particular focus is placed on understanding triadic velocity, pressure, and dilatation interactions, including the characterization of backscatter due to heat release and compressibility. Finally, the implications of these results for modeling practical premixed combustion problems are outlined.
The kinetic energy interceptor: Shooting a bullet with a bullet
1995-04-01
Although the Cold War has ended, the threat of proliferation with chemical, biological, and nuclear warheads continues. Two factors further increase the threat from these weapons of mass destruction: knowledge of missile technology has spread extensively, and, in recent years, many countries - some of them unfriendly to the US and its allies - have obtained short- and intermediate-range missiles. The threat posed by such missiles was amply demonstrated during the Gulf War. Thus, the need to protect US and allied forces from these weapons has never been greater. When nuclear-tipped defensive missiles, such as Sprint and Spartan, were phased out years ago, the US turned for its defense to kinetic-energy {open_quotes}kill{close_quotes} interceptors - missiles that destroy an enemy missile by striking it with lethal force and accuracy at some point in its trajectory. The Patriot missile is probably the best-known kinetic-energy (KE) interceptor in the US defensive arsenal. To counter the spreading threat of proliferation, LLNL and other laboratories have been participating in a joint program funded by the Ballistic Missile Defense Organization (BMDO), within the Department of Defense, to develop defensive missile systems. Participants are designing, testing, and certifying KE interceptors to defend against current and future missile threats. These research efforts are described.
Kinetic Energy of Tornadoes in the United States.
Fricker, Tyler; Elsner, James B
2015-01-01
Tornadoes can cause catastrophic destruction. Here total kinetic energy (TKE) as a metric of destruction is computed from the fraction of the tornado path experiencing various damage levels and a characteristic wind speed for each level. The fraction of the path is obtained from a model developed for the Nuclear Regulatory Commission that combines theory with empirical data. TKE is validated as a useful metric by comparing it to other indexes and loss indicators. Half of all tornadoes have TKE exceeding 62.1 GJ and a quarter have TKE exceeding 383.2 GJ. One percent of the tornadoes have TKE exceeding 31.9 TJ. April has more energy than May with fewer tornadoes; March has more energy than June with half as many tornadoes. September has the least energy but November and December have the fewest tornadoes. Alabama ranks number one in terms of tornado energy with 2.48 PJ over the period 2007-2013. TKE can be used to help better understand the changing nature of tornado activity.
Kinetic Energy of Tornadoes in the United States
Fricker, Tyler; Elsner, James B.
2015-01-01
Tornadoes can cause catastrophic destruction. Here total kinetic energy (TKE) as a metric of destruction is computed from the fraction of the tornado path experiencing various damage levels and a characteristic wind speed for each level. The fraction of the path is obtained from a model developed for the Nuclear Regulatory Commission that combines theory with empirical data. TKE is validated as a useful metric by comparing it to other indexes and loss indicators. Half of all tornadoes have TKE exceeding 62.1 GJ and a quarter have TKE exceeding 383.2 GJ. One percent of the tornadoes have TKE exceeding 31.9 TJ. April has more energy than May with fewer tornadoes; March has more energy than June with half as many tornadoes. September has the least energy but November and December have the fewest tornadoes. Alabama ranks number one in terms of tornado energy with 2.48 PJ over the period 2007–2013. TKE can be used to help better understand the changing nature of tornado activity. PMID:26132830
When and how does a prominence-like jet gain kinetic energy?
Liu, Jiajia; Liu, Rui; Zhang, Quanhao; Liu, Kai; Shen, Chenglong; Wang, S.; Wang, Yuming
2014-02-20
A jet is a considerable amount of plasma being ejected from the chromosphere or lower corona into the higher corona and is a common phenomenon. Usually, a jet is triggered by a brightening or a flare, which provides the first driving force to push plasma upward. In this process, magnetic reconnection is thought to be the mechanism to convert magnetic energy into thermal, nonthermal, and kinetic energies. However, most jets could reach an unusual high altitude and end much later than the end of its associated flare. This fact implies that there is another way to continuously transfer magnetic energy into kinetic energy even after the reconnection. The picture described above is well known in the community, but how and how much magnetic energy is released through a way other than reconnection is still unclear. By studying a prominence-like jet observed by SDO/AIA and STEREO-A/EUVI, we find that the continuous relaxation of the post-reconnection magnetic field structure is an important process for a jet to climb up higher than it could through only reconnection. The kinetic energy of the jet gained through the relaxation is 1.6 times that gained from the reconnection. The resultant energy flux is hundreds of times larger than the flux required for the local coronal heating, suggesting that such jets are a possible source to keep the corona hot. Furthermore, rotational motions appear all the time during the jet. Our analysis suggests that torsional Alfvén waves induced during reconnection could not be the only mechanism to release magnetic energy and drive jets.
A Rolling Pendulum Bob: Conservation of Energy and Partitioning of Kinetic Energy.
ERIC Educational Resources Information Center
Helrich, Carl; Lehman, Thomas
1979-01-01
Describes a pendulum in which the spherical bob can roll on a track of the same arc as it swings when suspended by a cord. Comparison of the motion in the two mentioned cases shows the effect of rotational kinetic energy when the bob rolls. (GA)
ENERGY DISSIPATION IN MAGNETIC NULL POINTS AT KINETIC SCALES
Olshevsky, Vyacheslav; Lapenta, Giovanni; Divin, Andrey; Eriksson, Elin; Markidis, Stefano
2015-07-10
We use kinetic particle-in-cell and MHD simulations supported by an observational data set to investigate magnetic reconnection in clusters of null points in space plasma. The magnetic configuration under investigation is driven by fast adiabatic flux rope compression that dissipates almost half of the initial magnetic field energy. In this phase powerful currents are excited producing secondary instabilities, and the system is brought into a state of “intermittent turbulence” within a few ion gyro-periods. Reconnection events are distributed all over the simulation domain and energy dissipation is rather volume-filling. Numerous spiral null points interconnected via their spines form null lines embedded into magnetic flux ropes; null point pairs demonstrate the signatures of torsional spine reconnection. However, energy dissipation mainly happens in the shear layers formed by adjacent flux ropes with oppositely directed currents. In these regions radial null pairs are spontaneously emerging and vanishing, associated with electron streams and small-scale current sheets. The number of spiral nulls in the simulation outweighs the number of radial nulls by a factor of 5–10, in accordance with Cluster observations in the Earth's magnetosheath. Twisted magnetic fields with embedded spiral null points might indicate the regions of major energy dissipation for future space missions such as the Magnetospheric Multiscale Mission.
NASA Astrophysics Data System (ADS)
Reitsma, G.; Zettergren, H.; Boschman, L.; Bodewits, E.; Hoekstra, R.; Schlathölter, T.
2013-12-01
We report on 30 keV He2 + collisions with naphthalene (C10H8) molecules, which leads to very extensive fragmentation. To unravel such complex fragmentation patterns, we designed and constructed an experimental setup, which allows for the determination of the full momentum vector by measuring charged collision products in coincidence in a recoil ion momentum spectrometer type of detection scheme. The determination of fragment kinetic energies is found to be considerably more accurate than for the case of mere coincidence time-of-flight spectrometers. In fission reactions involving two cationic fragments, typically kinetic energy releases of 2-3 eV are observed. The results are interpreted by means of density functional theory calculations of the reverse barriers. It is concluded that naphthalene fragmentation by collisions with keV ions clearly is much more violent than the corresponding photofragmentation with energetic photons. The ion-induced naphthalene fragmentation provides a feedstock of various small hydrocarbonic species of different charge states and kinetic energy, which could influence several molecule formation processes in the cold interstellar medium and facilitates growth of small hydrocarbon species on pre-existing polycyclic aromatic hydrocarbons.
NASA Astrophysics Data System (ADS)
Abdulhalim, I.
1995-03-01
A microscopic many-body model is proposed for the kinetics of metastable defects (MSDs) in hydrogenated amorphous silicon (a-Si:H). It is based on the existence of short-lived large energy fluctuations which induce transient traps for carriers that release their energy and enhance the creation or annihilation of MSDs. The expressions found for the photoinduced and thermally induced creation and annihilation rates' coefficients explain the dependence on the variety of parameters.
NASA Technical Reports Server (NTRS)
Dare, P. M.; Smith, P. J.
1983-01-01
The eddy kinetic energy budget is calculated for a 48-hour forecast of an intense occluding winter cyclone associated with a strong well-developed jet stream. The model output consists of the initialized (1200 GMT January 9, 1975) and the 12, 24, 36, and 48 hour forecast fields from the Drexel/NCAR Limited Area Mesoscale Prediction System (LAMPS) model. The LAMPS forecast compares well with observations for the first 24 hours, but then overdevelops the low-level cyclone while inadequately developing the upper-air wave and jet. Eddy kinetic energy was found to be concentrated in the upper-troposphere with maxima flanking the primary trough. The increases in kinetic energy were found to be due to an excess of the primary source term of kinetic energy content, which is the horizontal flux of eddy kinetic energy over the primary sinks, and the generation and dissipation of eddy kinetic energy.
NASA Technical Reports Server (NTRS)
Dare, P. M.; Smith, P. J.
1983-01-01
The eddy kinetic energy budget is calculated for a 48-hour forecast of an intense occluding winter cyclone associated with a strong well-developed jet stream. The model output consists of the initialized (1200 GMT January 9, 1975) and the 12, 24, 36, and 48 hour forecast fields from the Drexel/NCAR Limited Area Mesoscale Prediction System (LAMPS) model. The LAMPS forecast compares well with observations for the first 24 hours, but then overdevelops the low-level cyclone while inadequately developing the upper-air wave and jet. Eddy kinetic energy was found to be concentrated in the upper-troposphere with maxima flanking the primary trough. The increases in kinetic energy were found to be due to an excess of the primary source term of kinetic energy content, which is the horizontal flux of eddy kinetic energy over the primary sinks, and the generation and dissipation of eddy kinetic energy.
Statistical rate theory and kinetic energy-resolved ion chemistry: theory and applications.
Armentrout, P B; Ervin, Kent M; Rodgers, M T
2008-10-16
Ion chemistry, first discovered 100 years ago, has profitably been coupled with statistical rate theories, developed about 80 years ago and refined since. In this overview, the application of statistical rate theory to the analysis of kinetic-energy-dependent collision-induced dissociation (CID) reactions is reviewed. This procedure accounts for and quantifies the kinetic shifts that are observed as systems increase in size. The statistical approach developed allows straightforward extension to systems undergoing competitive or sequential dissociations. Such methods can also be applied to the reverse of the CID process, association reactions, as well as to quantitative analysis of ligand exchange processes. Examples of each of these types of reactions are provided and the literature surveyed for successful applications of this statistical approach to provide quantitative thermochemical information. Such applications include metal-ligand complexes, metal clusters, proton-bound complexes, organic intermediates, biological systems, saturated organometallic complexes, and hydrated and solvated species.
An integral turbulent kinetic energy analysis of free shear flows
NASA Technical Reports Server (NTRS)
Peters, C. E.; Phares, W. J.
1973-01-01
Mixing of coaxial streams is analyzed by application of integral techniques. An integrated turbulent kinetic energy (TKE) equation is solved simultaneously with the integral equations for the mean flow. Normalized TKE profile shapes are obtained from incompressible jet and shear layer experiments and are assumed to be applicable to all free turbulent flows. The shear stress at the midpoint of the mixing zone is assumed to be directly proportional to the local TKE, and dissipation is treated with a generalization of the model developed for isotropic turbulence. Although the analysis was developed for ducted flows, constant-pressure flows were approximated with the duct much larger than the jet. The axisymmetric flows under consideration were predicted with reasonable accuracy. Fairly good results were also obtained for the fully developed two-dimensional shear layers, which were computed as thin layers at the boundary of a large circular jet.
Mass independent kinetic energy reducing inlet system for vacuum environment
Reilly, Peter T. A. [Knoxville, TN
2010-12-14
A particle inlet system comprises a first chamber having a limiting orifice for an incoming gas stream and a micrometer controlled expansion slit. Lateral components of the momentum of the particles are substantially cancelled due to symmetry of the configuration once the laminar flow converges at the expansion slit. The particles and flow into a second chamber, which is maintained at a lower pressure than the first chamber, and then moves into a third chamber including multipole guides for electromagnetically confining the particle. The vertical momentum of the particles descending through the center of the third chamber is minimized as an upward stream of gases reduces the downward momentum of the particles. The translational kinetic energy of the particles is near-zero irrespective of the mass of the particles at an exit opening of the third chamber, which may be advantageously employed to provide enhanced mass resolution in mass spectrometry.
Mass independent kinetic energy reducing inlet system for vacuum environment
Reilly, Peter T.A.
2014-05-13
A particle inlet system comprises a first chamber having a limiting orifice for an incoming gas stream and a micrometer controlled expansion slit. Lateral components of the momentum of the particles are substantially cancelled due to symmetry of the configuration once the laminar flow converges at the expansion slit. The particles and flow into a second chamber, which is maintained at a lower pressure than the first chamber, and then moves into a third chamber including multipole guides for electromagnetically confining the particle. The vertical momentum of the particles descending through the center of the third chamber is minimized as an upward stream of gases reduces the downward momentum of the particles. The translational kinetic energy of the particles is near-zero irrespective of the mass of the particles at an exit opening of the third chamber, which may be advantageously employed to provide enhanced mass resolution in mass spectrometry.
Mass independent kinetic energy reducing inlet system for vacuum environment
Reilly, Peter T.A.
2013-12-03
A particle inlet system comprises a first chamber having a limiting orifice for an incoming gas stream and a micrometer controlled expansion slit. Lateral components of the momentum of the particles are substantially cancelled due to symmetry of the configuration once the laminar flow converges at the expansion slit. The particles and flow into a second chamber, which is maintained at a lower pressure than the first chamber, and then moves into a third chamber including multipole guides for electromagnetically confining the particle. The vertical momentum of the particles descending through the center of the third chamber is minimized as an upward stream of gases reduces the downward momentum of the particles. The translational kinetic energy of the particles is near-zero irrespective of the mass of the particles at an exit opening of the third chamber, which may be advantageously employed to provide enhanced mass resolution in mass spectrometry.
Kinetic energy distributions of ions after surface collisions
Short, R.T.; Todd, P.J.; Grimm, C.C.
1991-01-01
As a part of the development of an organic ion microprobe, to be used for imaging of particular organic compounds in biological tissue, various methods of quadrupole-based tandem mass spectroscopy (MS/MS) have been investigated. High transmission efficiency is essential for the success of the organic ion microprobe, due to expected low analyte concentrations in biological tissue and the potential for sample damage from prolonged exposure to the primary ion beam. MS/MS is necessary for organic ion imaging because of the complex nature of the biological matrices. The goal of these studies of was to optimize the efficiency of daughter ion production and transmission by first determining daughter ion properties and then designing ion optics based on those properties. The properties of main interest are daughter ion kinetic energy and angular distribution. 1 fig.
Utilization of rotor kinetic energy storage for hybrid vehicles
Hsu, John S.
2011-05-03
A power system for a motor vehicle having an internal combustion engine, the power system comprises an electric machine (12) further comprising a first excitation source (47), a permanent magnet rotor (28) and a magnetic coupling rotor (26) spaced from the permanent magnet rotor and at least one second excitation source (43), the magnetic coupling rotor (26) also including a flywheel having an inertial mass to store kinetic energy during an initial acceleration to an operating speed; and wherein the first excitation source is electrically connected to the second excitation source for power cycling such that the flywheel rotor (26) exerts torque on the permanent magnet rotor (28) to assist braking and acceleration of the permanent magnet rotor (28) and consequently, the vehicle. An axial gap machine and a radial gap machine are disclosed and methods of the invention are also disclosed.
Experimental evidence of the decrease of kinetic energy of hadrons in passing through atomic nuclei
NASA Technical Reports Server (NTRS)
Strugalski, Z.
1985-01-01
Hadrons with kinetic energies higher than the pion production threshold lose their kinetic energies monotonically in traversing atomic nuclei, due to the strong interactions in nuclear matter. This phenomenon is a crude analogy to the energy loss of charged particles in their passage through materials. Experimental evidence is presented.
Energy scavenging strain absorber: application to kinetic dielectric elastomer generator
NASA Astrophysics Data System (ADS)
Jean-Mistral, C.; Beaune, M.; Vu-Cong, T.; Sylvestre, A.
2014-03-01
Dielectric elastomer generators (DEGs) are light, compliant, silent energy scavengers. They can easily be incorporated into clothing where they could scavenge energy from the human kinetic movements for biomedical applications. Nevertheless, scavengers based on dielectric elastomers are soft electrostatic generators requiring a high voltage source to polarize them and high external strain, which constitutes the two major disadvantages of these transducers. We propose here a complete structure made up of a strain absorber, a DEG and a simple electronic power circuit. This new structure looks like a patch, can be attached on human's wear and located on the chest, knee, elbow… Our original strain absorber, inspired from a sailing boat winch, is able to heighten the external available strain with a minimal factor of 2. The DEG is made of silicone Danfoss Polypower and it has a total area of 6cm per 2.5cm sustaining a maximal strain of 50% at 1Hz. A complete electromechanical analytical model was developed for the DEG associated to this strain absorber. With a poling voltage of 800V, a scavenged energy of 0.57mJ per cycle is achieved with our complete structure. The performance of the DEG can further be improved by enhancing the imposed strain, by designing a stack structure, by using a dielectric elastomer with high dielectric permittivity.
Effect of the electronic kinetic energy on the elastic strain in metallic multilayers
NASA Astrophysics Data System (ADS)
Huberman, M. L.; Grimsditch, M.
1992-09-01
A recent theory of induced strain in metallic multilayers, caused by electron transfer effects, is revised by taking into account the electronic kinetic energy. When this is done, it is found that the predicted sign of the strain is opposite to what was found previously. For a multilayer having abrupt composition changes, the predicted magnitude of the strain is greater by a factor of 9/5 than what was found previously, whereas for a multilayer having smooth composition changes, it is the same as what was found previously.
The main beam correction term in kinetic energy release from metastable peaks.
Petersen, Allan Christian
2017-08-26
The correction term for the precursor ion signal width in determination of kinetic energy release is reviewed and the correction term is formally derived. The derived correction term differs from the traditionally applied term. An experimental finding substantiates the inaccuracy in the latter. The application of the 'T-value' to study kinetic energy release is found preferable to kinetic energy release distributions when the metastable peaks are slim and simple Gaussians. For electronically predissociated systems a 'borderline zero' kinetic energy release can be directly interpreted in terms of reaction dynamics with strong curvature in the reaction coordinate. This article is protected by copyright. All rights reserved.
Understanding the Pulsar High Energy Emission: Macroscopic and Kinetic Models
NASA Astrophysics Data System (ADS)
Kalapotharakos, Constantinos; Brambilla, Gabriele; Timokhin, Andrey; Kust Harding, Alice; Kazanas, Demos
2017-08-01
Pulsars are extraordinary objects powered by the rotation of magnetic fields of order 10^8, 10^12G anchored onto neutron stars and rotating with periods 10^(-3)-10s. These fields mediate the conversion of their rotational energy into MHD winds and at the same time accelerate particles to energies sufficiently high to produce GeV photons. Fermi, since its launch in 2008, has established several trends among the observed gamma-ray pulsar properties playing a catalytic role in the current modeling of the high energy emission in pulsar magnetospheres. We judiciously use the guidance provided by the Fermi data to yield meaningful constraints on the macroscopic parameters of our global dissipative pulsar magnetosphere models. Our FIDO (Force-Free Inside, Dissipative Outside) models indicate that the dissipative regions lie outside the light cylinder near the equatorial current sheet. Our models reproduce the light-curve phenomenology while a detailed comparison of the model spectral properties with those observed by Fermi reveals the dependence of the macroscopic conductivity parameter on the spin-down rate providing a unique insight into the understanding of the physical mechanisms behind the high-energy emission in pulsar magnetospheres. Finally, we further exploit these important results by building self-consistent 3D global kinetic particle-in-cell (PIC) models which, eventually, provide the dependence of the macroscopic parameter behavior (e.g. conductivity) on the microphysical properties (e.g. particle multiplicities, particle injection rates). Our PIC models provide field structures and particle distributions that are not only consistent with each other but also able to reproduce a broad range of the observed gamma-ray phenomenology (light curves and spectral properties) of both young and millisecond pulsars.
Detailed Kinetic Modeling of Processes Relevant To Fusion Energy
NASA Astrophysics Data System (ADS)
Mehl, Marco; Armstrong, Michael; Zaug, Joseph; Crowhurst, Jonathan; Radousky, Harry; Stavrou, Elissaios
2016-10-01
Carbon based materials have been proposed as candidates for the fabrication of plasma-facing components in the design of fusion energy devices. Although these components are not supposed to be in direct contact with the core fusion plasma, plasma instabilities and the harsh environment they are exposed to can cause the degradation of plasma-exposed components and the transfer of contaminants into the plasma followed by deposition of byproducts. In order to investigate the chemistry involved in these processes and to assist the development of models suitable to understand the long term consequences of the carbon ablation/deposition cycle, an inductively coupled plasma flow reactor (ICPFR) has been developed. The ICPFR allows the atomization of carbon containing precursors to high temperatures (in the order of 10000K) and the characterization of the gas and solid species formed downsteam from the plasma source through spectroscopic techniques. In parallel to the experimental analysis a comprehensive set of fluid dynamic and detailed kinetic simulations are used to analyze the data. The combination of these two approaches resulted in a validated and comprehensive chemical model for the formation of carbon deposits in carbon contaminated cooling plasmas. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Rapid laser induced energy transfer in atomic systems
NASA Technical Reports Server (NTRS)
Harris, S. E.; Young, J. F.
1978-01-01
Analytical and experimental studies of the rapid transfer of stored populations from metastable states to selected target states of a different species are reported. Both laser-induced or laser-switched collision and laser-induced two-photon spontaneous emission are described. It is shown that the laser-induced collision method is particularly useful in the visible and UV spectral regions. It has applications in photochemistry, gas-phase kinetics, and in high-power, high-energy gas-phase lasers. The anti-Stokes source is useful in the VUV and soft X-ray spectral regions.
Computation Molecular Kinetics Model of HZE Induced Cell Cycle Arrest
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.; Ren, Lei
2004-01-01
Cell culture models play an important role in understanding the biological effectiveness of space radiation. High energy and charge (HZE) ions produce prolonged cell cycle arrests at the G1/S and G2/M transition points in the cell cycle. A detailed description of these phenomena is needed to integrate knowledge of the expression of DNA damage in surviving cells, including the determination of relative effectiveness factors between different types of radiation that produce differential types of DNA damage and arrest durations. We have developed a hierarchical kinetics model that tracks the distribution of cells in various cell phase compartments (early G1, late G1, S, G2, and M), however with transition rates that are controlled by rate-limiting steps in the kinetics of cyclin-cdk's interactions with their families of transcription factors and inhibitor molecules. The coupling of damaged DNA molecules to the downstream cyclin-cdk inhibitors is achieved through a description of the DNA-PK and ATM signaling pathways. For HZE irradiations we describe preliminary results, which introduce simulation of the stochastic nature of the number of direct particle traversals per cell in the modulation of cyclin-cdk and cell cycle population kinetics. Comparison of the model to data for fibroblast cells irradiated photons or HZE ions are described.
Computation Molecular Kinetics Model of HZE Induced Cell Cycle Arrest
NASA Technical Reports Server (NTRS)
Cucinotta, Francis A.; Ren, Lei
2004-01-01
Cell culture models play an important role in understanding the biological effectiveness of space radiation. High energy and charge (HZE) ions produce prolonged cell cycle arrests at the G1/S and G2/M transition points in the cell cycle. A detailed description of these phenomena is needed to integrate knowledge of the expression of DNA damage in surviving cells, including the determination of relative effectiveness factors between different types of radiation that produce differential types of DNA damage and arrest durations. We have developed a hierarchical kinetics model that tracks the distribution of cells in various cell phase compartments (early G1, late G1, S, G2, and M), however with transition rates that are controlled by rate-limiting steps in the kinetics of cyclin-cdk's interactions with their families of transcription factors and inhibitor molecules. The coupling of damaged DNA molecules to the downstream cyclin-cdk inhibitors is achieved through a description of the DNA-PK and ATM signaling pathways. For HZE irradiations we describe preliminary results, which introduce simulation of the stochastic nature of the number of direct particle traversals per cell in the modulation of cyclin-cdk and cell cycle population kinetics. Comparison of the model to data for fibroblast cells irradiated photons or HZE ions are described.
Accurate spectral numerical schemes for kinetic equations with energy diffusion
NASA Astrophysics Data System (ADS)
Wilkening, Jon; Cerfon, Antoine J.; Landreman, Matt
2015-08-01
We examine the merits of using a family of polynomials that are orthogonal with respect to a non-classical weight function to discretize the speed variable in continuum kinetic calculations. We consider a model one-dimensional partial differential equation describing energy diffusion in velocity space due to Fokker-Planck collisions. This relatively simple case allows us to compare the results of the projected dynamics with an expensive but highly accurate spectral transform approach. It also allows us to integrate in time exactly, and to focus entirely on the effectiveness of the discretization of the speed variable. We show that for a fixed number of modes or grid points, the non-classical polynomials can be many orders of magnitude more accurate than classical Hermite polynomials or finite-difference solvers for kinetic equations in plasma physics. We provide a detailed analysis of the difference in behavior and accuracy of the two families of polynomials. For the non-classical polynomials, if the initial condition is not smooth at the origin when interpreted as a three-dimensional radial function, the exact solution leaves the polynomial subspace for a time, but returns (up to roundoff accuracy) to the same point evolved to by the projected dynamics in that time. By contrast, using classical polynomials, the exact solution differs significantly from the projected dynamics solution when it returns to the subspace. We also explore the connection between eigenfunctions of the projected evolution operator and (non-normalizable) eigenfunctions of the full evolution operator, as well as the effect of truncating the computational domain.
Estimates of meteoroid kinetic energies from observations of infrasonic airwaves
NASA Astrophysics Data System (ADS)
Edwards, Wayne N.; Brown, Peter G.; Revelle, Douglas O.
2006-06-01
Signal properties of the acoustic waves produced from meteoroids impacting the Earth's atmosphere in the approximate size range of 0.1 10 m diameter have been analyzed at infrasonic frequencies. From these data, we have produced a series of empirical relations between the far-field acoustic signature of the bolide shocks and meteor source energies by correlating infrasonic observations of those fireballs which are also detected by earth-observing satellites. Adopting a similar approach as has been previously employed for man-made explosives, signal properties such as acoustic amplitude, signal energy/power and signal-to-noise ratio, are shown, after high-altitude wind corrections, to be useful tools in estimating the kinetic energy of a bolide. Comparison of bolide infrasound data to ground-based explosive tests show that the acoustic amplitudes from airwaves generated by small bolide events (<7 kt TNT equivalent) attenuate more rapidly than nuclear or chemical explosions. As well, acoustic amplitude values for bolides are systematically lower than acoustic amplitudes measured for equivalent ground-based explosions. This is interpreted to be largely due to bolide acoustic sources being at high altitudes in the atmosphere. We find from our analysis that these heights are on average located between 20 and 30 km. Larger events (>7 kt) mimic man-made explosions in terms of range dependence, but offset in amplitude equivalent to ˜20 km source altitudes. This is consistent with instrumental observations of fireballs and the expectation that larger meteoroids (greater than a few meters in diameter), should penetrate deeper into the atmosphere on average. Applying these new relationships to historical events, we find that the August 3, 1963 bolide detected infrasonically near the Prince Edward Islands off the coast of South Africa, previously estimated to have an energy of 1100 kt, may have had a much smaller energy of 266±90 kt. This energy revision brings the
Kinetic simulation of thermally induced metastability in the tungsten-carbon system
NASA Astrophysics Data System (ADS)
Demetriou, Marios Demetri
2001-11-01
A dynamic computational model is developed within the context of classical nucleation theory for thermally induced non-equilibrium phase transitions. The conditions for this model are those encountered in rapid thermal processing of invariantly nucleating compound phases. The kinetic variables used in the model were directly obtained from the free energy formulations that characterize the stable and metastable equilibria amongst participating phases. The isothermal as well as non-isothermal kinetics were simulated by means of stochastic equations which model the fluctuational process of crystal nucleation along with the deterministic process of crystal growth. A strategy to evaluate the static (isothermal) and dynamic (non-isothermal) effects of nucleation transience based on time scale analogy is outlined and validated by contrasting the results of the dynamic model against those obtained from a steady state model. The developed model was applied to the W-C compound-forming binary system. The stable phase equilibria were reproduced using free energy data obtained from literature, while the metastable ones were obtained by extrapolating the stable equilibria into regions of metastability. The model was utilized to simulate the kinetics of graphitization during non-equilibrium peritectic melting of WC. The isothermal kinetic analysis suggests that graphitization becomes extremely rapid when annealing at large superheatings, while the highest crystallization rate was found to occur at the metastable congruent melting point of WC (˜3107 K) where 1-ppm crystallize in ˜2 nanoseconds. The non-isothermal kinetic analysis suggests that increasing the heating rate suppresses graphitization, while graphitization may be completely bypassed by the rapidly forming metastable liquid when processing under extreme rapid heating (˜108 K/s) beyond the metastable congruent melting point of WC. The model was also utilized to simulate the kinetics of phase selection during non
RNA folding pathways and kinetics using 2D energy landscapes.
Senter, Evan; Dotu, Ivan; Clote, Peter
2015-01-01
RNA folding pathways play an important role in various biological processes, such as (i) the hok/sok (host-killing/suppression of killing) system in E. coli to check for sufficient plasmid copy number, (ii) the conformational switch in spliced leader (SL) RNA from Leptomonas collosoma, which controls trans splicing of a portion of the '5 exon, and (iii) riboswitches--portions of the 5' untranslated region of messenger RNA that regulate genes by allostery. Since RNA folding pathways are determined by the energy landscape, we describe a novel algorithm, FFTbor2D, which computes the 2D projection of the energy landscape for a given RNA sequence. Given two metastable secondary structures A, B for a given RNA sequence, FFTbor2D computes the Boltzmann probability p(x, y) = Z(x,y)/Z that a secondary structure has base pair distance x from A and distance y from B. Using polynomial interpolationwith the fast Fourier transform,we compute p(x, y) in O(n(5)) time and O(n(2)) space, which is an improvement over an earlier method, which runs in O(n(7)) time and O(n(4)) space. FFTbor2D has potential applications in synthetic biology, where one might wish to design bistable switches having target metastable structures A, B with favorable pathway kinetics. By inverting the transition probability matrix determined from FFTbor2D output, we show that L. collosoma spliced leader RNA has larger mean first passage time from A to B on the 2D energy landscape, than 97.145% of 20,000 sequences, each having metastable structures A, B. Source code and binaries are freely available for download at http://bioinformatics.bc.edu/clotelab/FFTbor2D. The program FFTbor2D is implemented in C++, with optional OpenMP parallelization primitives.
Lee, Joe; Graves, David B.; Kazi, Haseeb; Gaddam, Sneha; Kelber, Jeffry A.
2013-07-15
In-situ x-ray photoelectron spectroscopy (XPS) and ex-situ Fourier transform infrared studies of He plasma and Ar{sup +} ion bombardment pretreatments of organosilicate glass demonstrate that such pretreatments inhibit subsequent O{sub 2} plasma-induced carbon loss by forming a SiO{sub 2}-like damaged overlayer, and that the degree of protection correlates directly with increased ion kinetic energies, but not with the thickness of the SiO{sub 2} overlayer. This thickness is observed by XPS to be roughly constant and <1 nm regardless of ion energies involved. The data indicate that ion kinetic energies are an important parameter in protective noble gas plasma pretreatments to inhibit O{sub 2} plasma-induced carbon loss.
A Comparison of Kinetic Energy and Momentum in Special Relativity and Classical Mechanics
ERIC Educational Resources Information Center
Riggs, Peter J.
2016-01-01
Kinetic energy and momentum are indispensable dynamical quantities in both the special theory of relativity and in classical mechanics. Although momentum and kinetic energy are central to understanding dynamics, the differences between their relativistic and classical notions have not always received adequate treatment in undergraduate teaching.…
Droplet kinetic energy of moving spray-plate center-pivot irrigation sprinklers
USDA-ARS?s Scientific Manuscript database
The kinetic energy of discrete water drops impacting a bare soil surface generally leads to a drastic reduction in water infiltration rate due to formation of a seal on the soil surface. Under center-pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy development ...
USDA-ARS?s Scientific Manuscript database
The kinetic energy of discrete drops impacting a bare soil surface is generally observed to lead to a drastic reduction in water infiltration rate due to soil surface seal formation. Under center pivot sprinkler irrigation, kinetic energy transferred to the soil prior to crop canopy development can...
A Comparison of Kinetic Energy and Momentum in Special Relativity and Classical Mechanics
ERIC Educational Resources Information Center
Riggs, Peter J.
2016-01-01
Kinetic energy and momentum are indispensable dynamical quantities in both the special theory of relativity and in classical mechanics. Although momentum and kinetic energy are central to understanding dynamics, the differences between their relativistic and classical notions have not always received adequate treatment in undergraduate teaching.…
The Rainfall and Rainfall Kinetic Energy Intensity-Duration of Landslides and Debris flow in Taiwan
NASA Astrophysics Data System (ADS)
Chang, Jui-Ming; Chen, Hongey
2016-04-01
This research used Joss-Waldvogel Disdrometers (JWD) which set in Shiment catchment, Northern Taiwan and Chishan catchment, Southern Taiwan to record rainfall kinetic energy data, to find the relationship between rainfall kinetic energy and rainfall intensity in these two areas. The distance between the two areas is less than 150 km. These data help the researchers and showed that the equations of relationship were ekN =28.7* (1-0.7027*exp(-0.0395*I)) and ekS=27.4*(1-0.5954*exp(-0.0345*I)). Generally, rainfall kinetic energy in Northern Taiwan is higher than in Southern Taiwan during rainfall period. Also, the occurring time and rainfall records of 143 landslide events from 2006 to 2012 were analyzed. The rainfall-intensity (I-D) relationship could be used to build rainfall threshold which were IN=15.13 D-0.28 and IS=47.58 D-0.35. In brief, the rainfall feature in landslide of Northern Taiwan had low rainfall intensity, long rainfall duration and low average accumulative rainfall. By combining rainfall kinetic energy and rainfall threshold, rainfall kinetic energy threshold could be established, which were ¯E N=13.83 D-0.04 and ¯E S =15.59 D-0.02. The results showed that not only for rainfall but also for rainfall kinetic energy threshold, the values of thresholds in North were lower than those in South. Due to impaction energy of rainfall to ground surface, rainfall kinetic energy would not forever increase. Therefore, rainfall kinetic energy threshold is also a useful tool for landslide warning. Key words: Rainfall kinetic energy, Rainfall threshold, Rainfall kinetic energy threshold, Landslide
NASA Astrophysics Data System (ADS)
Montoya, M.; Rojas, J.; Lobato, I.
2008-12-01
The kinetic energy distribution as a function of mass of final fragments (m) from low energy fission of $^{234}U$, measured with the Lohengrin spectrometer by Belhafaf et al. presents a peak around m=108 and another around m = 122. The authors attribute the first peak to the evaporation of a large number of neutrons around the corresponding mass number; and the second peak to the distribution of the primary fragment kinetic energy. Nevertheless, the theoretical calculations related to primary distribution made by Faust et al. do not result in a peak around m = 122. In order to clarify this apparent controversy, we have made a numerical experiment in which the masses and the kinetic energy of final fragments are calculated, assuming an initial distribution of the kinetic energy without peaks on the standard deviation as function of fragment mass. As a result we obtain a pronounced peak on the standard deviation of the kinetic energy distribution around m = 109, a depletion from m = 121 to m = 129, and an small peak around m = 122, which is not as big as the measured by Belhafaf et al. Our simulation also reproduces the experimental results on the yield of the final mass, the average number of emitted neutrons as a function of the provisional mass (calculated from the values of the final kinetic energy of the complementary fragments) and the average value of fragment kinetic energy as a function of the final mass.
Laplacian-level density functionals for the kinetic energy density and exchange-correlation energy
NASA Astrophysics Data System (ADS)
Perdew, John P.; Constantin, Lucian A.
2007-04-01
We construct a Laplacian-level meta-generalized-gradient-approximation (meta-GGA) for the noninteracting (Kohn-Sham orbital) positive kinetic energy density τ of an electronic ground state of density n . This meta-GGA is designed to recover the fourth-order gradient expansion τGE4 in the appropriate slowly varying limit and the von Weizsäcker expression τW=∣∇n∣2/(8n) in the rapidly varying limit. It is constrained to satisfy the rigorous lower bound τW(r)⩽τ(r) . Our meta-GGA is typically a strong improvement over the gradient expansion of τ for atoms, spherical jellium clusters, jellium surfaces, the Airy gas, Hooke’s atom, one-electron Gaussian density, quasi-two-dimensional electron gas, and nonuniformly scaled hydrogen atom. We also construct a Laplacian-level meta-GGA for exchange and correlation by employing our approximate τ in the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA density functional. The Laplacian-level TPSS gives almost the same exchange-correlation enhancement factors and energies as the full TPSS, suggesting that τ and ∇2n carry about the same information beyond that carried by n and ∇n . Our kinetic energy density integrates to an orbital-free kinetic energy functional that is about as accurate as the fourth-order gradient expansion for many real densities (with noticeable improvement in molecular atomization energies), but considerably more accurate for rapidly varying ones.
Vertical kinetic energy and turbulent dissipation in the ocean
NASA Astrophysics Data System (ADS)
Thurnherr, A. M.; Kunze, E.; Toole, J. M.; St. Laurent, L.; Richards, K. J.; Ruiz-Angulo, A.
2015-09-01
Oceanic internal waves are closely linked to turbulence. Here a relationship between vertical wave number (kz) spectra of fine-scale vertical kinetic energy (VKE) and turbulent dissipation ɛ is presented using more than 250 joint profiles from five diverse dynamic regimes, spanning latitudes between the equator and 60°. In the majority of the spectra VKE varies as kz-2. Scaling VKE with √ɛ collapses the off-equatorial spectra to within √2 but underestimates the equatorial spectrum. The simple empirical relationship between VKE and ɛ fits the data better than a common shear-and-strain fine-scale parameterization, which significantly underestimates ɛ in the two data sets that are least consistent with the Garrett-Munk (GM) model. The new relationship between fine-scale VKE and dissipation rate can be interpreted as an alternative, single-parameter scaling for turbulent dissipation in terms of fine-scale internal wave vertical velocity that requires no reference to the GM model spectrum.
Hindcasts of Integrated Kinetic Energy in North Atlantic Tropical Cyclones
NASA Astrophysics Data System (ADS)
Kozar, Michael; Misra, Vasubandhu
2015-04-01
Integrated kinetic energy (IKE) is a recently developed metric that evaluates the destructive potential of a tropical cyclone by assessing the size and strength of its wind field. Despite the potential usefulness of the IKE metric, there are few, if any, operational tools that are specifically designed to forecast IKE in real-time. Therefore, a system of artificial neural networks is created to produce deterministic and probabilistic projections of IKE in North Atlantic tropical cyclones out to 72 hours from a series of relevant environmental and storm specific normalized input parameters. In an effort to assess its real-time skill, this IKE forecasting system is run in a mock-operational mode for the 1990 to 2011 North Atlantic hurricane seasons. Hindcasts of IKE are produced in this manner by running the neural networks with hindcasted input parameters from NOAA's second generation Global Ensemble Forecasting System reforecast dataset. Ultimately, the results of the hindcast exercises indicate that the neural network system is capable of skillfully forecasting IKE in an operational setting at a level significantly higher than climatology and persistence. Ultimately, forecasts of IKE from these neural networks could potentially be an asset for operational meteorologists that would complement existing forecast tools in an effort to better assess the damage potential of landfalling tropical cyclones, particularly with regards to storm surge damage.
NonBoussinesq effects on vorticity and kinetic energy production
NASA Astrophysics Data System (ADS)
Ravichandran, S.; Dixit, Harish; Govindarajan, Rama
2015-11-01
The Boussinesq approximation, commonly employed in weakly compressible or incompressible flows, neglects changes in inertia due to changes in the density. However, the nonBoussinesq terms can lead to a kind of centrifugal instability for small but sharp density variations, and therefore cannot be neglected under such circumstances (see, e.g.,
Numerical investigation of kinetic energy dynamics during autoignition of n-heptane/air mixture
NASA Astrophysics Data System (ADS)
Lucena Kreppel Paes, Paulo; Brasseur, James; Xuan, Yuan
2015-11-01
Many engineering applications involve complex turbulent reacting flows, where nonlinear, multi-scale turbulence-combustion couplings are important. Direct representation of turbulent reacting flow dynamics is associated with prohibitive computational costs, which makes it necessary to employ turbulent combustion models to account for the effects of unresolved scales on resolved scales. Classical turbulence models are extensively employed in reacting flow simulations. However, they rely on assumptions about the energy cascade, which are valid for incompressible, isothermal homogeneous isotropic turbulence. A better understanding of the turbulence-combustion interactions is required for the development of more accurate, physics-based sub-grid-scale models for turbulent reacting flows. In order to investigate the effects of reaction-induced density, viscosity, and pressure variations on the turbulent kinetic energy, Direct Numerical Simulation (DNS) of autoignition of partially-premixed, lean n-heptane/air mixture in three-dimensional homogeneous isotropic turbulence has been performed. This configuration represents standard operating conditions of Homogeneous-Charge Compression-Ignition (HCCI) engines. The differences in the turbulent kinetic energy balance between the present turbulent reacting flow and incompressible, isothermal homogeneous isotropic turbulence are highlighted at different stages during the autoignition process.
From the Kinetic Energy Recovery System to the Thermo-Hydraulic Hybrid Motor Vehicle
NASA Astrophysics Data System (ADS)
Cristescu, Corneliu; Drumea, Petrin; Guta, Dragos; Dumitrescu, Catalin
2011-12-01
The paper presents some theoretical and experimental results obtained by the Hydraulics and Pneumatics Research Institute INOE 2000-IHP with its partners, regarding the creating of one hydraulic system able to recovering the kinetic energy of the motor vehicles, in the braking phases, and use this recovered energy in the starting and accelerating phases. Also, in the article is presented a testing stand, which was especially designed for testing the hydraulic system for recovery the kinetic energy. Through mounting of the kinetic energy recovering hydraulic system, on one motor vehicle, this vehicle became a thermo-hydraulic hybrid vehicle. Therefore, the dynamic behavior was analyzed for the whole hybrid motor vehicle, which includes the energy recovery system. The theoretical and experimental results demonstrate the possible performances of the hybrid vehicle and that the kinetic energy recovery hydraulic systems are good means to increase energy efficiency of the road motor vehicles and to decrease of the fuel consumption.
Making waves: Kinetic processes controlling surface evolution during low energy ion sputtering
NASA Astrophysics Data System (ADS)
Chan, Wai Lun; Chason, Eric
2007-06-01
When collimated beams of low energy ions are used to bombard materials, the surface often develops a periodic pattern or "ripple" structure. Different types of patterns are observed to develop under different conditions, with characteristic features that depend on the substrate material, the ion beam parameters, and the processing conditions. Because the patterns develop spontaneously, without applying any external mask or template, their formation is the expression of a dynamic balance among fundamental surface kinetic processes, e.g., erosion of material from the surface, ion-induced defect creation, and defect-mediated evolution of the surface morphology. In recent years, a comprehensive picture of the different kinetic mechanisms that control the different types of patterns that form has begun to emerge. In this article, we provide a review of different mechanisms that have been proposed and how they fit together in terms of the kinetic regimes in which they dominate. These are grouped into regions of behavior dominated by the directionality of the ion beam, the crystallinity of the surface, the barriers to surface roughening, and nonlinear effects. In sections devoted to each type of behavior, we relate experimental observations of patterning in these regimes to predictions of continuum models and to computer simulations. A comparison between theory and experiment is used to highlight strengths and weaknesses in our understanding. We also discuss the patterning behavior that falls outside the scope of the current understanding and opportunities for advancement.
Shear flow-induced detachment kinetics of Dictyostelium discoideum cells from solid substrate.
Décavé, Emmanuel; Garrivier, Daniel; Bréchet, Yves; Fourcade, Bertrand; Bruckert, Franz
2002-01-01
Using Dictyostelium discoideum as a model organism of specific and nonspecific adhesion, we studied the kinetics of shear flow-induced cell detachment. For a given cell, detachment occurs for values of the applied hydrodynamic stress above a threshold. Cells are removed from the substrate with an apparent first-order rate constant that strongly depends on the applied stress. The threshold stress depends on cell size and physicochemical properties of the substrate, but is not affected by depolymerization of the actin and tubulin cytoskeleton. In contrast, the kinetics of cell detachment is almost independent of cell size, but is strongly affected by a modification of the substrate and the presence of an intact actin cytoskeleton. These results are interpreted in the framework of a peeling model. The threshold stress and the cell-detachment rate measure the local equilibrium energy and the dissociation rate constant of the adhesion bridges, respectively. PMID:11964228
When and How Does A Prominence-like Jet Gain Kinetic Energy?
NASA Astrophysics Data System (ADS)
Liu, J.; Wang, Y.; Zhang, Q.; Liu, K.; Shen, C.
2013-12-01
Usually a jet is triggered by a brightening or flare, which provides the first driving force. In this process, magnetic reconnection is thought to be the mechanism to convert magnetic energy into jet's kinetic energy. However, most jets could reach an unusual height and end far after the end of its associated flare. This fact implies another way continuously transferring magnetic energy into kinetic energy after the reconnection. This picture is well known, but how and how much magnetic energy is released through the way other than the reconnection is still unclear. Here, through studying a prominence-like jet observed by AIA and EUVI, we reveal the continuously relaxation of post-reconnection magnetic field structure is an important process to support a jet. The kinetic energy of the jet gained through this way is 1.6 times of that from the reconnection. The resultant energy flux is hundreds of the required for local coronal heating, suggesting such jets are a possible source to keep corona hot. Rotational motion appearing all the time during the jet implies the torsional Alfven wave induced during reconnection is not the only mechanism to release magnetic energy and drive jets. Left column: Difference images taken by SDO/AIA at 304A passband. The FOV of the images is 430"x430". Right column: Difference images from STEREO-A/EUVI at the same passband. The FOV is 450"x450". Since STEREO-A was 120 degree apart away from SDO on 2012 July 8, the SDO limb event right happened ondisk in the view of STEREO-A. Black and red solid curve: integrated intensity over the cross-section of the jet at different height at 19:11 UT and 19:47 UT, respectively. The two horizontal dashed lines are their average values. Black and red dashed curve with asterisks: axial speed with errors of the eight sub-jets shown in Figure 3 at 19:11 UT and 19:47 UT , respectively. Blue dashed curve with diamonds: angular speed with errors of the jet at different height.
UV-induced reaction kinetics of dilinoleoylphosphatidylethanolamine monolayers.
Viitala, T; Peltonen, J
1999-01-01
The UV-induced reactivity of dilinoleoylphosphatidylethanolamine (DLiPE) Langmuir and Langmuir-Blodgett films has been studied by in situ measurements of the changes in the mean molecular area, UV-vis and Fourier transform infrared spectroscopy, and atomic force microscopy (AFM). Optimum orientation and packing density of the DLiPE molecules in the monolayer were achieved by adding uranyl acetate to the subphase. A first-order reaction kinetic model was successfully fitted to the experimental reaction kinetics data obtained at a surface pressure of 30 mN/m. Topographical studies of LB films by AFM were performed on bilayer structures as a function of subphase composition and UV irradiation time. The orientational effect of the uranyl ions on the monolayer molecules was observed as an enhanced homogeneity of the freshly prepared monomeric LB films. However, the long-term stability of these films proved to be bad; clear reorganization and loss of a true monolayer structure were evidenced by the AFM images. This instability was inhibited for the UV-irradiated films, indicating that the UV irradiation gave rise to a cross-linked structure. PMID:10233096
NASA Astrophysics Data System (ADS)
Yu-Jen, Wang; Tsung-Yi, Chuang; Jui-Hsin, Yu
2017-09-01
Vibration-based energy harvesters have been developed as power sources for wireless sensor networks. Because the vibration frequency of the environment is varied with surrounding conditions, how to design an adaptive energy harvester is a practical topic. This paper proposes a design for a piezoelectric energy harvester possessing the ability to self-adjust its resonant frequency in rotational environments. The effective length of a trapezoidal cantilever is extended by centrifugal force from a rotating wheel to vary its area moment of inertia. The analytical solution for the natural frequency of the piezoelectric energy harvester was derived from the parameter design process, which could specify a structure approaching resonance at any wheel rotating frequency. The kinetic equation and electrical damping induced by power generation were derived from a Lagrange method and a mechanical-electrical coupling model, respectively. An energy harvester with adequate parameters can generate power at a wide range of car speeds. The output power of an experimental prototype composed of piezoelectric thin films and connected to a 3.3 MΩ external resistor was approximately 70-140 μW at wheel speeds ranging from 200 to 700 RPM. These results demonstrate that the proposed piezoelectric energy harvester can be applied as a power source for the wireless tire pressure monitoring sensor.
Kinetics of motility-induced phase separation and swim pressure
NASA Astrophysics Data System (ADS)
Patch, Adam; Yllanes, David; Marchetti, M. Cristina
2017-01-01
Active Brownian particles (ABPs) represent a minimal model of active matter consisting of self-propelled spheres with purely repulsive interactions and rotational noise. Here we examine the pressure of ABPs in two dimensions in both closed boxes and systems with periodic boundary conditions and show that its nonmonotonic behavior with density is a general property of ABPs and is not the result of finite-size effects. We correlate the time evolution of the mean pressure towards its steady-state value with the kinetics of motility-induced phase separation. For parameter values corresponding to phase-separated steady states, we identify two dynamical regimes. The pressure grows monotonically in time during the initial regime of rapid cluster formation, overshooting its steady-state value and then quickly relaxing to it, and remains constant during the subsequent slower period of cluster coalescence and coarsening. The overshoot is a distinctive feature of active systems.
Kinetic energy management in road traffic injury prevention: a call for action.
Khorasani-Zavareh, Davoud; Bigdeli, Maryam; Saadat, Soheil; Mohammadi, Reza
2015-01-01
By virtue of their variability, mass and speed have important roles in transferring energies during a crash incidence (kinetic energy). The sum of kinetic energy is important in determining an injury severity and that is equal to one half of the vehicle mass multiplied by the square of the vehicle speed. To meet the Vision Zero policy (a traffic safety policy) prevention activities should be focused on vehicle speed management. Understanding the role of kinetic energy will help to develop measures to reduce the generation, distribution, and effects of this energy during a road traffic crash. Road traffic injury preventive activities necessitate Kinetic energy management to improve road user safety. © 2015 KUMS, All rights reserved.
Turbulent Kinetic Energy (TKE) Budgets Using 5-beam Doppler Profilers
NASA Astrophysics Data System (ADS)
Guerra, M. A.; Thomson, J. M.
2016-12-01
Field observations of turbulence parameters are important for the development of hydrodynamic models, understanding contaminant mixing, and predicting sediment transport. The turbulent kinetic energy (TKE) budget quantifies where turbulence is being produced, dissipated or transported at a specific site. The Nortek Signature 5-beam AD2CP was used to measure velocities at high sampling rates (up to 8 Hz) at Admiralty Inlet and Rich Passage in Puget Sound, WA, USA. Raw along-beam velocity data is quality controlled and is used to estimate TKE spectra, spatial structure functions, and Reynolds stress tensors. Exceptionally low Doppler noise in the data enables clear observations of the inertial sub-range of isotropic turbulence in both the frequency TKE spectra and the spatial structure functions. From these, TKE dissipation rates are estimated following Kolmogorov's theory of turbulence. The TKE production rates are estimated using Reynolds stress tensors together with the vertical shear in the mean flow. The Reynolds stress tensors are estimated following the methodology of Dewey and Stinger (2007), which is significantly improved by inclusion of the 5th beam (as opposed to the conventional 4). These turbulence parameters are used to study the TKE budget along the water column at the two sites. Ebb and flood production and dissipation rates are compared through the water column at both sites. At Admiralty Inlet, dissipation exceeds production during ebb while the opposite occurs during flood because the proximity to a lateral headland. At Rich Passage, production exceeds dissipation through the water column for all tidal conditions due to a vertical sill in the vicinity of the measurement site.
Spectral study of wintertime kinetic energy of the Northern Hemisphere in the troposphere
NASA Technical Reports Server (NTRS)
Lee, H. N.; Zhao, Z.; Kao, S. K.
1983-01-01
Characteristics of the kinetic energy of wind fields at various pressure levels were analyzed, and significant wavenumbers in the wavenumber-frequency domain were identified. The nonlinear interaction terms of the kinetic energy equation were examined, and the distribution of the kinetic energy at the 850 mb, 500 mb, and 200 mb levels was calculated. A 5 deg latitude-longitude square grid was used, with NMC data for the 1975-1976 winter in the 20-60 deg N at 500 mb and 20-85 deg N for the 200 mb and 850 mb levels. The kinetic energy distribution was determined to be geography-dependent, with wavenumbers 6-9 westerly waves in the midfrequency range contributing significantly to kinetic energy maxima over the North Pacific and the east coast of North America. The contribution of the nonlinear interactions of these waves, which correspond to the longitudinal convergence of the kinetic energy flux, was found to be larger than the meridional convergence of the kinetic energy flux, and to occur mainly between 30-50 deg N. The nonlinear interactions were a negative contribution over the North Pacific at the 200 mb level.
Combustor kinetic energy efficiency analysis of the hypersonic research engine data
NASA Astrophysics Data System (ADS)
Hoose, K. V.
1993-11-01
A one-dimensional method for measuring combustor performance is needed to facilitate design and development scramjet engines. A one-dimensional kinetic energy efficiency method is used for measuring inlet and nozzle performance. The objective of this investigation was to assess the use of kinetic energy efficiency as an indicator for scramjet combustor performance. A combustor kinetic energy efficiency analysis was performed on the Hypersonic Research Engine (HRE) data. The HRE data was chosen for this analysis due to its thorough documentation and availability. The combustor, inlet, and nozzle kinetic energy efficiency values were utilized to determine an overall engine kinetic energy efficiency. Finally, a kinetic energy effectiveness method was developed to eliminate thermochemical losses from the combustion of fuel and air. All calculated values exhibit consistency over the flight speed range. Effects from fuel injection, altitude, angle of attack, subsonic-supersonic combustion transition, and inlet spike position are shown and discussed. The results of analyzing the HRE data indicate that the kinetic energy efficiency method is effective as a measure of scramjet combustor performance.
Spectral study of wintertime kinetic energy of the Northern Hemisphere in the troposphere
NASA Technical Reports Server (NTRS)
Lee, H. N.; Zhao, Z.; Kao, S. K.
1983-01-01
Characteristics of the kinetic energy of wind fields at various pressure levels were analyzed, and significant wavenumbers in the wavenumber-frequency domain were identified. The nonlinear interaction terms of the kinetic energy equation were examined, and the distribution of the kinetic energy at the 850 mb, 500 mb, and 200 mb levels was calculated. A 5 deg latitude-longitude square grid was used, with NMC data for the 1975-1976 winter in the 20-60 deg N at 500 mb and 20-85 deg N for the 200 mb and 850 mb levels. The kinetic energy distribution was determined to be geography-dependent, with wavenumbers 6-9 westerly waves in the midfrequency range contributing significantly to kinetic energy maxima over the North Pacific and the east coast of North America. The contribution of the nonlinear interactions of these waves, which correspond to the longitudinal convergence of the kinetic energy flux, was found to be larger than the meridional convergence of the kinetic energy flux, and to occur mainly between 30-50 deg N. The nonlinear interactions were a negative contribution over the North Pacific at the 200 mb level.
Rainfall kinetic energy-intensity and rainfall momentum-intensity relationships for Cape Verde
NASA Astrophysics Data System (ADS)
Sanchez-Moreno, Juan Francisco; Mannaerts, Chris M.; Jetten, Victor; Löffler-Mang, Martin
2012-08-01
Momentum and kinetic energy of rainfall are widely used indices to describe erosivity, the ability of rainfall to detach soil particles and erode the landscape. An optical laser disdrometer was installed in Santiago Island, Cape Verde, between September 2008 and September 2010 to measure rainfall intensity and size distribution of raindrops. A total time series of 5129 observations of radar reflectivity, visibility, rainfall intensity and number of particles were gathered. Rainfall kinetic energy expenditure KEtime (J m-2 h-1), kinetic energy content KEmm (J m-2 mm-1) and momentum flux MtA (kg m s-1 m-2 s-1) were calculated and fitted to different known experimental equations. The best fit between rainfall intensity and kinetic energy expenditure, kinetic energy content and momentum were obtained with power-law equations. These equations were validated in two independent events corresponding to 2008 and 2009, producing high correlation coefficients. The results show that for Cape Verde, KEtime is a more appropriate index to relate with rainfall intensity, and that kinetic energy expenditure and momentum flux are interchangeable parameters for erosivity estimation. New relationships relating kinetic energy and rainfall intensity, and momentum and rainfall intensity were derived, which contribute to the characterization of rainfall originating from tropical depressions at lower latitudes.
Kinetics of pulse-induced photoluminescence from a semiconductor quantum dot.
Rukhlenko, Ivan D; Leonov, Mikhail Yu; Turkov, Vadim K; Litvin, Aleksandr P; Baimuratov, Anvar S; Baranov, Alexander V; Fedorov, Anatoly V
2012-12-03
Optical methods, which allow the determination of the dominant channels of energy and phase relaxation, are the most universal techniques for the investigation of semiconductor quantum dots. In this paper, we employ the kinetic Pauli equation to develop the first generalized model of the pulse-induced photoluminescence from the lowest-energy eigenstates of a semiconductor quantum dot. Without specifying the shape of the excitation pulse and by assuming that the energy and phase relaxation in the quantum dot may be characterized by a set of phenomenological rates, we derive an expression for the observable photoluminescence cross section, valid for an arbitrary number of the quantum dot's states decaying with the emission of secondary photons. Our treatment allows for thermal transitions occurring with both decrease and increase in energy between all the relevant eigenstates at room or higher temperature. We show that in the general case of N states coupled to each other through a bath, the photoluminescence kinetics from any of them is determined by the sum of N exponential functions, whose exponents are proportional to the respective decay rates. We illustrate the application of the developed model by considering the processes of resonant luminescence and thermalized luminescence from the quantum dot with two radiating eigenstates, and by assuming that the secondary emission is excited with either a Gaussian or exponential pulse. Analytic expressions describing the signals of secondary emission are analyzed, in order to elucidate experimental situations in which the relaxation constants may be reliably extracted from the photoluminescence spectra.
Laskin, Julia; Futrell, Jean H.
2015-02-01
We introduce a new approach for studying the kinetics of large ion fragmentation in the gas phase by coupling surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer with resonant ejection of selected fragment ions using a relatively short (5 ms) ejection pulse. The approach is demonstrated for singly protonated angiotensin III ions excited by collisions with a self-assembled monolayer of alkylthiol on gold (HSAM). The overall decomposition rate and rate constants of individual reaction channels are controlled by varying the kinetic energy of the precursor ion in a range of 65–95 eV. The kinetics of peptide fragmentation are probed by varying the delay time between resonant ejection and fragment ion detection at a constant total reaction time. RRKM modeling indicates that the shape of the kinetics plots is strongly affected by the shape and position of the energy deposition function (EDF) describing the internal energy distribution of the ion following ion-surface collision. Modeling of the kinetics data provides detailed information on the shape of the EDF and energy and entropy effects of individual reaction channels.
Prediction of free turbulent mixing using a turbulent kinetic energy method
NASA Technical Reports Server (NTRS)
Harsha, P. T.
1973-01-01
Free turbulent mixing of two-dimensional and axisymmetric one- and two-stream flows is analyzed by a relatively simple turbulent kinetic energy method. This method incorporates a linear relationship between the turbulent shear and the turbulent kinetic energy and an algebraic relationship for the length scale appearing in the turbulent kinetic energy equation. Good results are obtained for a wide variety of flows. The technique is shown to be especially applicable to flows with heat and mass transfer, for which nonunity Prandtl and Schmidt numbers may be assumed.
NASA Technical Reports Server (NTRS)
Che, H.; Goldstein, M. L.; Vinas, A. F.
2014-01-01
The observed steep kinetic scale turbulence spectrum in the solar wind raises the question of how that turbulence originates. Observations of keV energetic electrons during solar quiet time suggest them as a possible source of free energy to drive kinetic turbulence. Using particle-in-cell simulations, we explore how the free energy released by an electron two-stream instability drives Weibel-like electromagnetic waves that excite wave-wave interactions. Consequently, both kinetic Alfvénic and whistler turbulence are excited that evolve through inverse and forward magnetic energy cascades.
NASA Astrophysics Data System (ADS)
Mamedov, Bahtiyar Akber; Copuroglu, Ebru
2017-02-01
By using the Löwdin-α function method, we have analytically calculated the two-center kinetic energy integrals over Slater type orbitals (STOs). The two-center kinetic energy integrals are presented in terms of the two-center overlap integrals. A new approach is applicable to accurate calculations of two-center kinetic energy integral over STOs for arbitrary values of scaling parameters and interatomic distances. Obtained results show that the proposed method is easy to apply to the real systems, and has better calculation CPU time with compared to the existing approximations.
NASA Technical Reports Server (NTRS)
Schmid, L. A.
1977-01-01
The case of a cold gas in the absence of external force fields is considered. Since the only energy involved is kinetic energy, the total kinetic action (i.e., the space-time integral of the kinetic energy density) should serve as the total free-energy functional in this case, and as such should be a local minimum for all possible fluctuations about stable flow. This conjecture is tested by calculating explicit, manifestly covariant expressions for the first and second variations of the total kinetic action in the context of Lagrangian kinematics. The general question of the correlation between physical stability and the convexity of any action integral that can be interpreted as the total free-energy functional of the flow is discussed and illustrated for the cases of rectillinear and rotating shearing flows.
The role of latent heat in kinetic energy conversions of South Pacific cyclones
NASA Technical Reports Server (NTRS)
Kann, Deirdre M.; Vincent, Dayton G.
1986-01-01
The four-dimensional behavior of cyclone systems in the South Pacific Convergence Zone (SPCZ) is analyzed. Three cyclone systems, which occurred during the period from January 10-16, 1979, are examined using the data collected during the first special observing period of the FGGE. The effects of latent heating on the life cycles of the cyclones are investigated. Particular attention is given to the conversions of eddy available potential energy to eddy kinetic energy and of mean kinetic energy to eddy kinetic energy. The net radiation profile, sensible heat flux, total field of vertical motion, and latent heat component were computed. The life cycles of the cyclones are described. It is observed that the latent heating component accounts for nearly all the conversion in the three cyclones, and latent heating within the SPCZ is the major source of eddy kinetic energy for the cyclones.
The role of latent heat in kinetic energy conversions of South Pacific cyclones
NASA Technical Reports Server (NTRS)
Kann, Deirdre M.; Vincent, Dayton G.
1986-01-01
The four-dimensional behavior of cyclone systems in the South Pacific Convergence Zone (SPCZ) is analyzed. Three cyclone systems, which occurred during the period from January 10-16, 1979, are examined using the data collected during the first special observing period of the FGGE. The effects of latent heating on the life cycles of the cyclones are investigated. Particular attention is given to the conversions of eddy available potential energy to eddy kinetic energy and of mean kinetic energy to eddy kinetic energy. The net radiation profile, sensible heat flux, total field of vertical motion, and latent heat component were computed. The life cycles of the cyclones are described. It is observed that the latent heating component accounts for nearly all the conversion in the three cyclones, and latent heating within the SPCZ is the major source of eddy kinetic energy for the cyclones.
Platelet-activating factor-induced increases in glucose kinetics
Lang, C.H.; Dobrescu, C.; Hargrove, D.M.; Bagby, G.J.; Spitzer, J.J. )
1988-02-01
Platelet-activating factor (PAF) is a postulated mediator of many of the early hemodynamic effects of endotoxin. The aim of the present study was to determine whether in vivo administration of PAF could produce alterations in whole-body glucose metabolism that would mimic those seen during endotoxemia. Glucose kinetics were assessed in chronically catheterized conscious rats by the constant infusion of (6-{sup 3}H)- and (U-{sup 14}C)glucose before and for 4 h after either a bolus injection or a constant infusion of PAF. The bolus injection of PAF elevated the rate of glucose appearance (R{sub a}; 44%) for 1.5 h. The lower PAF infusion rate decreased blood pressure 11% to 104 mmHg, whereas the higher infusion rate decreased pressure 34% to 77 mmHg. Both PAF infusion rates produced elevations in plasma glucose and glucose R{sub a} throughout the 4-h infusion period in a dose-related manner. The PAF infusions also induced dose-related increases in plasma glucagon and catecholamine levels throughout the infusion period. Because the constant infusion of PAF did stimulate many of the hemodynamic and metabolic alterations produced by endotoxin, this study provides additional support for the potential importance of PAF as a mediator of the early hemodynamic and metabolic sequela of endotoxin shock. Furthermore, the PAF-induced changes in glucose metabolism appear to be mediated by the resultant elevation in plasma catecholamines.
Leading-order nonlocal kinetic energy in peridynamics for consistent energetics and wave dispersion
NASA Astrophysics Data System (ADS)
Dayal, Kaushik
2017-08-01
This work considers the approximation of peridynamics by strain-gradient models in the linear, one-dimensional setting. Strain-gradient expansions that approximate the peridynamic dispersion relation using Taylor series are compared to strain-gradient models that approximate the peridynamic elastic energy. The dynamic and energetic expansions differ from each other, and neither captures an important feature of peridynamics that mimics atomic-scale dynamics, namely that the frequency of short waves is bounded and non-zero. The paper next examines peridynamics as the limit model along a sequence of strain-gradient models that consistently approximate both the energetics and the dispersion properties of peridynamics. Formally examining the limit suggests that the inertial term in the dynamical equation of peridynamics - or equivalently, the peridynamic kinetic energy - is necessarily nonlocal in space to balance the spatial nonlocality in the elastic energy. The nonlocality in the kinetic energy is of leading-order in the following sense: classical elasticity is the zeroth-order theory in both the kinetically nonlocal peridynamics and the classical peridynamics, but once nonlocality in the elastic energy is introduced, it must be balanced by nonlocality in the kinetic energy at the same order. In that sense, the kinetic nonlocality is not a higher-order correction; rather, the kinetic nonlocality is essential for consistent energetics and dynamics even in the simplest setting. The paper then examines the implications of kinetically nonlocal peridynamics in the context of stationary and propagating discontinuities of the kinematic fields.
On the Equipartition of Kinetic Energy in an Ideal Gas Mixture
ERIC Educational Resources Information Center
Peliti, L.
2007-01-01
A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)
On the Equipartition of Kinetic Energy in an Ideal Gas Mixture
ERIC Educational Resources Information Center
Peliti, L.
2007-01-01
A refinement of an argument due to Maxwell for the equipartition of translational kinetic energy in a mixture of ideal gases with different masses is proposed. The argument is elementary, yet it may work as an illustration of the role of symmetry and independence postulates in kinetic theory. (Contains 1 figure.)
Determination of equivalent amounts of kinetic energy, work, and heat energy in the human body.
Cinar, Yildirim
2002-07-01
The goal of this study is determine the mechanical equivalent of heat and the functional capacity of metabolism of walking at a slow pace (velocity = 4022m/hour, length of a step=75cm, energy utilization of a 70 kg person is 200kcal/hour). 50 healthy physicians were chosen randomly, and up and down motion of the body were determined as 6cm while stepping. Based on these, the heat equivalent is 37.5kcal/hour for horizontal motion and 52.7kcal/hour for 6cm up-and-down bobbing motions of body, and the functional capacity of metabolism is at least 45% ([37.5+52.7]/200=45%) for slow walking state, that this capacity is twofold more than earlier information. Muscle converts kinetic energy (work) to heat via friction, and heat sources of the body, and the concepts of thermogenesis and the functional capacity of metabolism should be revised.
Energy Conservation Tests of a Coupled Kinetic-kinetic Plasma-neutral Transport Code
Stotler, D. P.; Chang, C. S.; Ku, S. H.; Lang, J.; Park, G.
2012-08-29
A Monte Carlo neutral transport routine, based on DEGAS2, has been coupled to the guiding center ion-electron-neutral neoclassical PIC code XGC0 to provide a realistic treatment of neutral atoms and molecules in the tokamak edge plasma. The DEGAS2 routine allows detailed atomic physics and plasma-material interaction processes to be incorporated into these simulations. The spatial pro le of the neutral particle source used in the DEGAS2 routine is determined from the uxes of XGC0 ions to the material surfaces. The kinetic-kinetic plasma-neutral transport capability is demonstrated with example pedestal fueling simulations.
Weijers, Mireille; Barneveld, Peter A; Cohen Stuart, Martien A; Visschers, Ronald W
2003-12-01
The heat-induced denaturation kinetics of two different sources of ovalbumin at pH 7 was studied by chromatography and differential scanning calorimetry. The kinetics was found to be independent of protein concentration and salt concentration, but was strongly dependent on temperature. For highly pure ovalbumin, the decrease in nondenatured native protein showed first-order dependence. The activation energy obtained with different techniques varied between 430 and 490 kJ*mole(-1). First-order behavior was studied in detail using differential scanning calorimetry. The calorimetric traces were irreversible and highly scan rate-dependent. The shape of the thermograms as well as the scan rate dependence can be explained by assuming that the thermal denaturation takes place according to a simplified kinetic process where N is the native state, D is denatured (or another final state) and k a first-order kinetic constant that changes with temperature, according to the Arrhenius equation. A kinetic model for the temperature-induced denaturation and aggregation of ovalbumin is presented. Commercially obtained ovalbumin was found to contain an intermediate-stable fraction (IS) of about 20% that was unable to form aggregates. The denaturation of this fraction did not satisfy first-order kinetics.
Vos, M.; Marmitt, G. G.; Finkelstein, Y.; Moreh, R.
2015-09-14
Reflection electron energy loss spectra from some insulating materials (CaCO{sub 3}, Li{sub 2}CO{sub 3}, and SiO{sub 2}) taken at relatively high incoming electron energies (5–40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO{sub 2}, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E − E{sub gap}){sup 1.5}. For CaCO{sub 3}, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li{sub 2}CO{sub 3} (7.5 eV) is the first experimental estimate.
NASA Astrophysics Data System (ADS)
Vos, M.; Marmitt, G. G.; Finkelstein, Y.; Moreh, R.
2015-09-01
Reflection electron energy loss spectra from some insulating materials (CaCO3, Li2CO3, and SiO2) taken at relatively high incoming electron energies (5-40 keV) are analyzed. Here, one is bulk sensitive and a well-defined onset of inelastic excitations is observed from which one can infer the value of the band gap. An estimate of the band gap was obtained by fitting the spectra with a procedure that includes the recoil shift and recoil broadening affecting these measurements. The width of the elastic peak is directly connected to the mean kinetic energy of the atom in the material (Doppler broadening). The experimentally obtained mean kinetic energies of the O, C, Li, Ca, and Si atoms are compared with the calculated ones, and good agreement is found, especially if the effect of multiple scattering is taken into account. It is demonstrated experimentally that the onset of the inelastic excitation is also affected by Doppler broadening. Aided by this understanding, we can obtain a good fit of the elastic peak and the onset of inelastic excitations. For SiO2, good agreement is obtained with the well-established value of the band gap (8.9 eV) only if it is assumed that the intensity near the edge scales as (E - Egap)1.5. For CaCO3, the band gap obtained here (7 eV) is about 1 eV larger than the previous experimental value, whereas the value for Li2CO3 (7.5 eV) is the first experimental estimate.
García-Aldea, David; Alvarellos, J E
2008-08-21
Following some recent ideas on the construction of kinetic energy density functionals that reproduce the linear response function of the homogeneous electron gas, a family of them with a nonlocal term based on the von Weizsacker functional and with a dependence on the logarithm of the density is presented. As localized systems are the most difficult to study with explicit kinetic functionals, in this paper we apply to atomic systems a number of families of fully nonlocal kinetic functionals. We have put our attention in both the total kinetic energy and the local behavior of the kinetic energy density, and the results clearly show the quality of these fully nonlocal functionals. They make a good description of the local behavior of the kinetic energy density and maintain good results for the total kinetic energies. We must remark that almost all the functionals discussed in the paper, when using an adequate reference density, can be evaluated as a single integral in momentum space, with a quasilinear scaling for the computational cost.
Ceriotti, Michele; Manolopoulos, David E
2012-09-07
Light nuclei at room temperature and below exhibit a kinetic energy which significantly deviates from the predictions of classical statistical mechanics. This quantum kinetic energy is responsible for a wide variety of isotope effects of interest in fields ranging from chemistry to climatology. It also furnishes the second moment of the nuclear momentum distribution, which contains subtle information about the chemical environment and has recently become accessible to deep inelastic neutron scattering experiments. Here, we show how, by combining imaginary time path integral dynamics with a carefully designed generalized Langevin equation, it is possible to dramatically reduce the expense of computing the quantum kinetic energy. We also introduce a transient anisotropic Gaussian approximation to the nuclear momentum distribution which can be calculated with negligible additional effort. As an example, we evaluate the structural properties, the quantum kinetic energy, and the nuclear momentum distribution for a first-principles simulation of liquid water.
Kinetic energy distribution of OH+ from water fragmentation by electron impact
NASA Astrophysics Data System (ADS)
Ferreira, Natalia; Sigaud, L.; Montenegro, E. C.
2017-07-01
The release of the highly reactive radical OH+ from the fragmentation of water by electron impact is made mostly through the OH++H0 channel. This channel ejects suprathermal OH+ ions with a kinetic energy distribution whose details are unexplored so far due to the difficulty in experimentally characterizing ions ejected with very low kinetic energy without another charged partner. These ions are studied here using the delayed extraction time-of-flight technique (DETOF). The structures and substructures in the kinetic energy distribution of OH+ associated with both single and double ionization are identified qualitatively and quantitatively. A comparison with the kinetic energy distribution of the complementary channel OH0+H+ , also originating from vacancies in the 1 b2 orbital, shows marked differences between the two, mainly regarding the relative role between the fragmentation involving the H2O+ ground state or via transitions to repulsive states.
New Ro-Vibrational Kinetic Energy Operators using Polyspherical Coordinates for Polyatomic Molecules
NASA Technical Reports Server (NTRS)
Schwenke, David W.; Kwak, Dochan (Technical Monitor)
2002-01-01
We illustrate how one can easily derive kinetic energy operators for polyatomic molecules using polyspherical coordinates with very general choices for z-axis embeddings arid angles used to specify relative orientations of internal vectors. Computer algebra is not required.
Klix, Christian L; Murata, Ken-ichiro; Tanaka, Hajime; Williams, Stephen R; Malins, Alex; Royall, C Patrick
2013-01-01
Colloidal clusters are an unusual state of matter where tunable interactions enable a sufficient reduction in their degrees of freedom that their energy landscapes can become tractable - they form a playground for statistical mechanics and promise unprecedented control of structure on the submicron lengthscale. We study colloidal clusters in a system where a short-ranged polymer-induced attraction drives clustering, while a weak, long-ranged electrostatic repulsion prevents extensive aggregation. We compare experimental yields of cluster structures with theory which assumes simple addition of competing isotropic interactions between the colloids. Here we show that for clusters of size 4 ≤ m ≤ 7, the yield of minimum energy clusters is much less than expected. We attribute this to an anisotropic self-organized surface charge distribution which leads to unexpected kinetic trapping. We introduce a model for the coupling between counterions and binding sites on the colloid surface with which we interpret our findings.
Modelling rainfall kinetic energy: a novel approach to erosion prediction and management
NASA Astrophysics Data System (ADS)
Nissan, H.; Toumi, R.
2013-12-01
Soil erosion is already a major global problem. Climate change and the rising world population will exert growing pressure on our land to deliver food and stability. This study presents a new and innovative application of a cloud resolving model, for use in soil erosion prediction studies. Rainfall kinetic energy flux is an important variable in erosion prediction, but is generally parameterized from intensity due to measurement difficulties. Instead, we show that a cloud resolving model can be used to dynamically simulate the kinetic energy of rain from basic physics, using four commonly used microphysics schemes. Rainfall kinetic energy flux is modelled during an idealized supercell storm with the Weather Research and Forecasting model. Results are within the range of observations and also capture the observed variability in kinetic energy flux for a given rainfall intensity, where current methods fail. Large raindrops are shown to contribute disproportionately to total kinetic energy flux compared with their number, suggesting that several existing relations between terminal velocity and size of raindrops are poorly suited for kinetic energy modelling. Treatment of raindrop size is tested and compared between the schemes, and factors influencing the erosive potential of rainfall will also be discussed. This work demonstrates the potential for conducting erosion prediction studies using a regional climate model. The method presented here may be easily extended for use in a full regional climate model with a microphysics parameterization scheme. This paves the way for full climate, and climate change, simulations of rainfall erosivity on regional to global scales and may contribute towards the ultimate integration of an erosion prediction scheme into climate models to allow coupled interactions with the atmosphere. Reference: Geophys. Res. Lett., 40, doi:10.1002/grl.50622 Schematic showing raindrop number density, rain mass flux and kinetic energy flux as
Makwana, K. D. Cattaneo, F.; Zhdankin, V.; Li, H.; Daughton, W.
2015-04-15
Simulations of decaying magnetohydrodynamic (MHD) turbulence are performed with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k{sub ⊥}{sup −1.3}. The kinetic code shows a spectral slope of k{sub ⊥}{sup −1.5} for smaller simulation domain, and k{sub ⊥}{sup −1.3} for larger domain. We estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. This work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.
Kinetic aspects of the formation of aluminium oxide by use of a microwave-induced plasma.
Quade, A; Steffen, H; Hippler, R; Wulff, H
2002-10-01
The oxidation of thin aluminium layers in a microwave plasma has been investigated to determine the kinetics of oxide growth. Thin Al-coatings were oxidized by means of a variety of gas mixtures, characterized by different partial pressures of oxygen, in microwave-induced plasmas of different power. To study the whole kinetic process the Al-metal and the oxide formed were investigated by means of a combination of grazing incidence X-ray reflectometry (GIXR) and grazing incidence X-ray diffractometry (GIXRD). XPS and FTIR spectroscopy confirmed the formation of stoichiometric Al(2)O(3). The alumina formed is X-ray amorphous. Quantitative description of oxide formation was achieved indirectly by determination of the decrease in the integrated intensity of the Al(111)-peak and the total thickness of the whole coating. These values enabled calculation of kinetic data. It was found that oxide growth was a combination of two simultaneous processes - diffusion and sputter processes. The diffusion coefficient D (cm(2) s(-1)) and the sputter rate S (nm s(-1)) were determined. The effect of the composition of the gas mixture, microwave power, and concentration of activated oxygen species on the oxidation process will be discussed. For calculation of the activation energy, E(A), of this plasma-enhanced diffusion process the temperature-dependence of D was investigated.
Garcia-Aldea, David; Alvarellos, J. E.
2008-02-15
We propose a kinetic energy density functional scheme with nonlocal terms based on the von Weizsaecker functional, instead of the more traditional approach where the nonlocal terms have the structure of the Thomas-Fermi functional. The proposed functionals recover the exact kinetic energy and reproduce the linear response function of homogeneous electron systems. In order to assess their quality, we have tested the total kinetic energies as well as the kinetic energy density for atoms. The results show that these nonlocal functionals give as good results as the most sophisticated functionals in the literature. The proposed scheme for constructing the functionals means a step ahead in the field of fully nonlocal kinetic energy functionals, because they are capable of giving better local behavior than the semilocal functionals, yielding at the same time accurate results for total kinetic energies. Moreover, the functionals enjoy the possibility of being evaluated as a single integral in momentum space if an adequate reference density is defined, and then quasilinear scaling for the computational cost can be achieved.
Model for Strain-Induced Precipitation Kinetics in Microalloyed Steels
NASA Astrophysics Data System (ADS)
Medina, Sebastian F.; Quispe, Alberto; Gomez, Manuel
2013-10-01
Based on Dutta and Sellars's expression for the start of strain-induced precipitation in microalloyed steels, a new model has been constructed which takes into account the influence of variables such as microalloying element percentages, strain, temperature, strain rate, and grain size. Although the equation given by these authors reproduces the typical "C" shape of the precipitation start time (P s) curve well, the expression is not reliable for all cases. Recrystallization-precipitation-time-temperature diagrams have been plotted thanks to a new experimental study carried out by means of hot torsion tests on approximately twenty microalloyed steels with different Nb, V, and Ti contents. Mathematical analysis of the results recommends the modification of some parameters such as the supersaturation ratio (K s) and constant B, which is no longer a constant, but a function of K s when the latter is calculated at the nose temperature (T N) of the P s curve. The value of parameter B is deduced from the minimum point or nose of the P s curve, where ∂t 0.05/∂T is equal to zero, and it can be demonstrated that B cannot be a constant. The new expressions for these parameters are derived from the latest studies undertaken by the authors and this work represents an attempt to improve the model. The expressions are now more consistent and predict the precipitation-time-temperature curves with remarkable accuracy. The model for strain-induced precipitation kinetics is completed by means of Avrami's equation.
Kinetic Energy Corrections for Slip-Stick Behavior in Brittle Adhesives
NASA Technical Reports Server (NTRS)
Macon, David J.; Anderson, Greg L.; McCool, Alex (Technical Monitor)
2001-01-01
Fracture mechanics is the study of the failure of a body that contains a flaw. In the energy balance approach to fracture mechanics, contributions from the external work and elastic strain energy are accounted for but rarely are corrections for the kinetic energy given. Under slip-stick conditions, part of the external work is expended as kinetic energy. The magnitude of this kinetic energy depends upon the shape of the crack. A specimen with a blunt crack will fail at a high load and the crack will catastrophically travel through the material until the kinetic energy is dissipated. Material with a sharp crack will fail at a lower load but will still be catastrophic in nature. A kinetic term is incorporated into the energy balance approach. This term accounts for the velocity of the crack after failure and how far the crack travels before arresting. This correction makes the shape of the initiation crack irrelevant. When applied to data generated by tapered double cantilever beam specimens under slip-stick conditions, the scatter in the measured critical strain energy release rate is significantly reduced.
Single-Strand Stacking Free Energy from DNA Beacon Kinetics
Aalberts, Daniel P.; Parman, John M.; Goddard, Noel L.
2003-01-01
DNA beacons are short single-stranded chains which can form closed hairpin shapes through complementary base pairing at their ends. Contrary to the common polymer theory assumption that only their loop length matters, experiments show that their closing kinetics depend on the loop composition. We have modeled the closing kinetics and in so doing have obtained stacking enthalpies and entropies for single-stranded nucleic acids. The resulting change of persistence length with temperature effects the dynamics. With a Monte Carlo study, we answer another polymer question of how the closing time scales with chain length, finding τ ∼ N2.44±0.02. There is a significant crossover for shorter chains, bringing the effective exponent into good agreement with experiment. PMID:12719250
Kinetics of processes and energy distribution in an electric discharge upon pumping a XeCl laser
Bychkov, Yurii I; Yampol'skaya, S A; Yastremskii, Arkadii G
2010-01-31
Radiation energies and efficiencies of the XeCl laser are calculated for different pump regimes in a broad range of variations in the initial parameters [pump energy of 50 - 350 J L{sup -1}, pulse duration of 30 - 150 ns, initial concentration of HCl molecules of (0.7 - 2.5) x 10{sup 17} cm{sup -3}]. The sequence of kinetic processes during which the pump energy is converted into induced radiation and heat is determined. It is shown that when 80% - 90% of the initial HCl concentration is used per pulse, the optimal ratio between the radiation energy and the laser efficiency is provided. In these regimes, about 50% of the pump energy is spent on production of excimer molecules in the entire range of the experimental parameters and for one HCl molecule 10 {+-} 1.5 eV is spent. (lasers)
Kinetic-energy operator in the effective shell-model interaction
Jaqua, L. ); Hasan, M.A. ); Vary, J.P. ); Barrett, B.R. )
1992-12-01
Differences in the Hartree-Fock and effective shell-model interaction arising from alternative treatments of the kinetic-energy operator in finite nuclear many-body problems are described. The Hartree-Fock single-particle energies and their relationship to experimental removal energies depend sensitively on whether or not the center-of-mass kinetic energy is retained in the nuclear Hamiltonian. Large effects in particle-hole energies are obtained which have important consequences for effective shell-model Hamiltonians. If the center-of-mass contribution of the kinetic-energy operator is removed from the Hamiltonian, substantial effects appear in a simple example of the shell-model spectra of [sup 16]O and [sup 17]O treated as four and five valence nucleons, respectively, outside a [sup 12]C core. The contributions to the energy coming from the valence, relative kinetic-energy operator push the energy spectra of both nuclei up by about 1 MeV relative to their ground states.
Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets
NASA Astrophysics Data System (ADS)
Chen, Lei; Zhang, Jie; Freund, William M.; Kong, Wei
2015-07-01
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs+ is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs+-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 106 helium atoms when the source temperature is between 14 K and 17 K.
Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets
Chen, Lei; Zhang, Jie; Freund, William M.; Kong, Wei
2015-07-28
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs{sup +} is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs{sup +}-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 10{sup 6} helium atoms when the source temperature is between 14 K and 17 K.
Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets.
Chen, Lei; Zhang, Jie; Freund, William M; Kong, Wei
2015-07-28
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs(+) is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs(+)-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 10(6) helium atoms when the source temperature is between 14 K and 17 K.
Effect of kinetic energy on the doping efficiency of cesium cations into superfluid helium droplets
Chen, Lei; Zhang, Jie; Freund, William M.; Kong, Wei
2015-01-01
We present an experimental investigation of the effect of kinetic energy on the ion doping efficiency of superfluid helium droplets using cesium cations from a thermionic emission source. The kinetic energy of Cs+ is controlled by the bias voltage of a collection grid collinearly arranged with the droplet beam. Efficient doping from ions with kinetic energies from 20 eV up to 480 V has been observed in different sized helium droplets. The relative ion doping efficiency is determined by both the kinetic energy of the ions and the average size of the droplet beam. At a fixed source temperature, the number of doped droplets increases with increasing grid voltage, while the relative ion doping efficiency decreases. This result implies that not all ions are captured upon encountering with a sufficiently large droplet, a deviation from the near unity doping efficiency for closed shell neutral molecules. We propose that this drop in ion doping efficiency with kinetic energy is related to the limited deceleration rate inside a helium droplet. When the source temperature changes from 14 K to 17 K, the relative ion doping efficiency decreases rapidly, perhaps due to the lack of viable sized droplets. The size distribution of the Cs+-doped droplet beam can be measured by deflection and by energy filtering. The observed doped droplet size is about 5 × 106 helium atoms when the source temperature is between 14 K and 17 K. PMID:26233132
Pressure induced manifold enhancement of Li-kinetics in FCC fullerene.
Das, Deya; Han, Sang Soo; Lee, Kwang-Ryeol; Singh, Abhishek K
2014-10-21
The reduction of the diffusion energy barrier for Li in electrodes is one of the required criteria to achieve better performances in Li ion batteries. Using density functional theory based calculations, we report a pressure induced manifold enhancement of Li-kinetics in bulk FCC fullerene. Scanning of the potential energy surface reveals a diffusion path with a low energy barrier of 0.62 eV, which reduces further under the application of hydrostatic pressure. The pressure induced reduction in the diffusion barrier continues till a uniform volume strain of 17.7% is reached. Further enhancement of strain increases the barrier due to the repulsion caused by C-C bond formation between two neighbouring fullerenes. The decrease in the barrier is attributed to the combined effect of charge transfer triggered by the enhanced interaction of Li with the fullerene as well as the change in profile of the local potential, which becomes more attractive for Li. The lowering of the barrier leads to an enhancement of two orders of magnitude in Li diffusivity at room temperature making pressurized bulk fullerene a promising artificial solid electrolyte interface (SEI) for a faster rechargeable battery.
NASA Astrophysics Data System (ADS)
Zhang, Peng; Lan, Pengfei; Feng, Zhengpeng; Zhang, Qingbin; Lu, Peixiang
2014-10-01
Here we present a novel method to improve the kinetic energy resolution of a velocity map imaging(VMI) spectrometer. The main modifications, compared to the original design of Eppink and Parker (1997 Rev. Sci. Instrum. 68 3477), are two additional grid electrodes. One of the electrodes is a grounded grid and the other is an arc-shaped grid with negative voltages (or positive voltages for an ions spectrometer). The arc-shaped electrode is axially symmetrical around the spectrometer axis. The field constructed by the two electrodes is to compensate the dispersion of the ‘v’-shaped energy resolution. Simulations by SIMION and reconstructions by the basis set expansion Abel transform method show that the kinetic energy resolution can be improved drastically by our new method. Furthermore, the accuracy in the determination of the kinetic energy of ion/electrons remains unchanged with respect to the original design.
A kinetic energy analysis of the meso beta-scale severe storm environment
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Printy, M. F.
1984-01-01
Analyses are performed of the meso beta-scale (20-200 km wavelengths and several hours to one-day periods) severe storm kinetic energy balance on the fifth day of the AVE SESAME campaign of May 1979. A 24-hr interval covering the antecedent, active and post-convective outbreak activity over Oklahoma are considered. Use is made of the kinetic energy budget equation (KEBE) for a finite volume in an isobaric coordinate system. Rawindsonde data with 75 km resolution were treated. The KEBE model covered changes in kinetic energy due to the cross contour flows, horizontal and vertical components of flux divergence, and volumic mass changes on synoptic and subsynoptic scales. The greatest variability was concentrated above 400 mb height and over the most intense storm activity. Energy was generated at the highest rates in divergence and decreased the most in convection. The meso beta-scale lacked sufficient resolution for analyzing mesoscale activity.
Neutron kinetics in moderators and SNM detection through epithermal-neutron-induced fissions
NASA Astrophysics Data System (ADS)
Gozani, Tsahi; King, Michael J.
2016-01-01
Extension of the well-established Differential Die Away Analysis (DDAA) into a faster time domain, where more penetrating epithermal neutrons induce fissions, is proposed and demonstrated via simulations and experiments. In the proposed method the fissions stimulated by thermal, epithermal and even higher-energy neutrons are measured after injection of a narrow pulse of high-energy 14 MeV (d,T) or 2.5 MeV (d,D) source neutrons, appropriately moderated. The ability to measure these fissions stems from the inherent correlation of neutron energy and time ("E-T" correlation) during the process of slowing down of high-energy source neutrons in common moderating materials such as hydrogenous compounds (e.g., polyethylene), heavy water, beryllium and graphite. The kinetic behavior following injection of a delta-function-shaped pulse (in time) of 14 MeV neutrons into such moderators is studied employing MCNPX simulations and, when applicable, some simple "one-group" models. These calculations served as a guide for the design of a source moderator which was used in experiments. Qualitative relationships between slowing-down time after the pulse and the prevailing neutron energy are discussed. A laboratory system consisting of a 14 MeV neutron generator, a polyethylene-reflected Be moderator, a liquid scintillator with pulse-shape discrimination (PSD) and a two-parameter E-T data acquisition system was set up to measure prompt neutron and delayed gamma-ray fission signatures in a 19.5% enriched LEU sample. The measured time behavior of thermal and epithermal neutron fission signals agreed well with the detailed simulations. The laboratory system can readily be redesigned and deployed as a mobile inspection system for SNM in, e.g., cars and vans. A strong pulsed neutron generator with narrow pulse (<75 ns) at a reasonably high pulse frequency could make the high-energy neutron induced fission modality a realizable SNM detection technique.
Measurement of the Kinetic Energy of a Body by Means of a Deformation.
ERIC Educational Resources Information Center
Perez, Pedro J.; And Others
1996-01-01
Describes a technique that measures the deformation produced in a plastic material by a falling ball in order to compute the ball's kinetic energy. Varying the parameters produces accurate results and gives students a good understanding of the measurement of energy. Combines various mechanical concepts that students have learned separately in…
Relativistic Momentum and Kinetic Energy, and E = mc[superscript 2
ERIC Educational Resources Information Center
Hu, Ben Yu-Kuang
2009-01-01
Based on relativistic velocity addition and the conservation of momentum and energy, I present simple derivations of the expressions for the relativistic momentum and kinetic energy of a particle, and for the formula E = mc[superscript 2]. (Contains 5 footnotes and 2 figures.)
NEW APPROACHES: Measurement of the kinetic energy of a body by means of a deformation
NASA Astrophysics Data System (ADS)
Pérez, Pedro J.; Castellvi, Francesc; Rosell, Joan I.
1996-07-01
The simple technique of measuring the deformation produced in a plastic material by a falling ball can be used to compute the ball's kinetic energy. Varying the parameters in this simple experiment can produce accurate results and give students a good understanding of the measurement of energy.
Measurement of the Kinetic Energy of a Body by Means of a Deformation.
ERIC Educational Resources Information Center
Perez, Pedro J.; And Others
1996-01-01
Describes a technique that measures the deformation produced in a plastic material by a falling ball in order to compute the ball's kinetic energy. Varying the parameters produces accurate results and gives students a good understanding of the measurement of energy. Combines various mechanical concepts that students have learned separately in…
Relativistic Momentum and Kinetic Energy, and E = mc[superscript 2
ERIC Educational Resources Information Center
Hu, Ben Yu-Kuang
2009-01-01
Based on relativistic velocity addition and the conservation of momentum and energy, I present simple derivations of the expressions for the relativistic momentum and kinetic energy of a particle, and for the formula E = mc[superscript 2]. (Contains 5 footnotes and 2 figures.)
Kinetic energy of rainfall an important driver of soil erosion - how reliable are our estimates?
NASA Astrophysics Data System (ADS)
Wilken, Florian; Sommer, Michael; Fiener, Peter
2016-04-01
The most important process initiating interrill erosion is the detachment of soil particles via splash processes. Splash erosion intensity is depending on soil and rainfall characteristics. Rainfall characteristics are essentially determined by the drop size and fall velocity, leading to a specific kinetic energy of rainfall. In consequence, the kinetic energy of rain events is often directly or indirectly included in erosion models to calculate splash erosion. Therefore, rainfall kinetic energy is commonly derived by empirical functions (e.g. RUSLE; Renard et al. 1997) from available rainfall intensity measurements. The aim of this study is to analyze the event type-specific uncertainties inherent in these empirical functions purely based on rainfall intensity measurements. Therefore, we compare rainfall energies calculated from rainfall intensities measured with a standard tipping bucket rain gauge to rainfall energy measurements taken by laser distrometers. These allow to calculate rainfall kinetic energy from a spectrum of measured drop sizes and fall velocities. The study was carried out in NE-Germany in a test area with an average annual precipitation of approximately 500 mm dominated by intense convective precipitation. We compare one year of data from two laser distrometers and two tipping buckets installed at two locations about 1 km apart. Our results show distinct differences for high intensity events between the measuring techniques. We found notably higher rainfall kinetic energy for high intensity events measured by the laser distrometer compared to the tipping bucked derived kinetic energy. This points to a measurement bias of high erosive rainfall events which would be of particular relevance for erosion studies.
Kinetic Kaleidoscope: Exploring Movement and Energy in the Visual Arts.
ERIC Educational Resources Information Center
Herman, Gail Neary; Hollingsworth, Patricia
Works of visual art contain an inner dynamism and energy that an individual's perceptual apparatus can translate into kinesthetic impressions, movement, and sound. Through this translation, a child's natural energies can interact with the artwork through multiple sensory experiences, enriching art appreciation. After a brief examination of the…
NASA Astrophysics Data System (ADS)
Davies, A. R.; Veron, F.; Oliver, M. J.
2014-12-01
The Southern Ocean is an iron limited, high nitrate, low chlorophyll region that draws considerable attention as a potential site for carbon drawdown through iron fertilization. However, there are no prolonged in-situ observations of the mechanisms driving naturally occurring blooms in this region. Here we present results from an APEX biofloat that continuously profiled the Drake Passage from ~ 2,000 m to the surface every two days. The biofloat measured the development and export of a naturally occurring phytoplankton bloom in the Drake Passage. Our analysis indicates that low levels of mesoscale kinetic energy coincided with the observed phytoplankton bloom. We postulate that low KE level are a precondition for bloom onset in the Drake Passage, which is confirmed by satellite observations. High levels of mesoscale kinetic energy immediately followed the phytoplankton bloom and appear to have facilitated organic carbon export to the deep ocean by changing the neutral density depths of aggregated cells. Furthermore, satellite observations in Drake Passage suggest that high levels of mesoscale kinetic energy limit bloom formation. We suggest that low mesoscale kinetic energy is a precondition for bloom formation in the Drake Passage before other potentially limiting factors become significant (e.g. grazing relation, macronutrients, micronutrients). If mesoscale kinetic energy were to impose a limitation on phytoplankton concentrations across the entire Southern Ocean, there may be regions unsuitable for geoengineered draw down of atmospheric carbon dioxide through large scale iron additions.
Momentum and eddy kinetic energy transports by a multiple microburst- producing storm
NASA Astrophysics Data System (ADS)
Lin, Yeong-Jer; Coover, John A.
1990-05-01
A comprehensive study of the structure and internal dynamics was made for a multiple microburst-producing storm for August 5, 1982, in Colorado during the Joint Airport Weather Studies (JAWS) Project at Denver's Stapleton International Airport. The analysis levels were contained between 0.25 and 2 km. The horizontal and vertical grid spacings were 0.5 and 0.25 km, respectively. These fields were subjected to internal consistency checks to determine the level of confidence before interpretation. Results show that the combined effects of misocyclone circulations, perturbation-pressure gradients, melting, buoyancy, and precipitation loading contribute to the maintenance of the microburst downdrafts in the atmospheric boundary layer (ABL). At low levels where the microbursts dominate, the presence of microburst gust fronts and diverging outflow enhances the vertical transport of horizontal momentum and eddy kinetic energy. The misocyclones located above the microbursts largely determine the transport of horizontal momentum and eddy kinetic energy there. In the microburst subdomain, a net transport of horizontal momentum and eddy kinetic energy is downward from the misocyclone to the surface. Its magnitude is directly proportional to the strength of a microburst at low levels and the misocyclone aloft. Budget studies of horizontal momentum flux and eddy kinetic energy within the storm domain and the microburst subdomain have added to a further understanding of the storm's structure and internal dynamics. The pressure and buoyancy effects are two main contributors to the generation/decay of horizontal momentum fluxes and eddy kinetic energy at the microburst levels.
Kinetics and Energy Transfer in Nonequilibrium Fluid Flows
1993-02-03
Crosley, Molecular Physics Laboratory, SRI International, Menlo Park, California 94025 Abstract Laser-induced fluorescence has reached maturity as an...FLUORESCENCE IN COMBUSTION The technique of laser-induced fluorescence has attained maturity in the field of combustion science. At the Twenty-fourth...HCO by the photolysis of slowly flowing acetaldehyde in a room temperature cell [12]. An excitation spectrum showing several bands of this electronic
Estimation of the kinetic energy dissipation in fall-arrest system and manikin during fall impact.
Wu, John Z; Powers, John R; Harris, James R; Pan, Christopher S
2011-04-01
Fall-arrest systems (FASs) have been widely applied to provide a safe stop during fall incidents for occupational activities. The mechanical interaction and kinetic energy exchange between the human body and the fall-arrest system during fall impact is one of the most important factors in FAS ergonomic design. In the current study, we developed a systematic approach to evaluate the energy dissipated in the energy absorbing lanyard (EAL) and in the harness/manikin during fall impact. The kinematics of the manikin and EAL during the impact were derived using the arrest-force time histories that were measured experimentally. We applied the proposed method to analyse the experimental data of drop tests at heights of 1.83 and 3.35 m. Our preliminary results indicate that approximately 84-92% of the kinetic energy is dissipated in the EAL system and the remainder is dissipated in the harness/manikin during fall impact. The proposed approach would be useful for the ergonomic design and performance evaluation of an FAS. STATEMENT OF RELEVANCE: Mechanical interaction, especially kinetic energy exchange, between the human body and the fall-arrest system during fall impact is one of the most important factors in the ergonomic design of a fall-arrest system. In the current study, we propose an approach to quantify the kinetic energy dissipated in the energy absorbing lanyard and in the harness/body system during fall impact.
Kinetic energy offsets for multicharged ions from an electron beam ion source.
Kulkarni, D D; Ahl, C D; Shore, A M; Miller, A J; Harriss, J E; Sosolik, C E; Marler, J P
2017-08-01
Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar(4+) and Ar(8+) ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.
Kinetic energy offsets for multicharged ions from an electron beam ion source
NASA Astrophysics Data System (ADS)
Kulkarni, D. D.; Ahl, C. D.; Shore, A. M.; Miller, A. J.; Harriss, J. E.; Sosolik, C. E.; Marler, J. P.
2017-08-01
Using a retarding field analyzer, we have measured offsets between the nominal and measured kinetic energy of multicharged ions extracted from an electron beam ion source (EBIS). By varying source parameters, a shift in ion kinetic energy was attributed to the trapping potential produced by the space charge of the electron beam within the EBIS. The space charge of the electron beam depends on its charge density, which in turn depends on the amount of negative charge (electron beam current) and its velocity (electron beam energy). The electron beam current and electron beam energy were both varied to obtain electron beams of varying space charge and these were related to the observed kinetic energy offsets for Ar4+ and Ar8+ ion beams. Knowledge of these offsets is important for studies that seek to utilize slow, i.e., low kinetic energy, multicharged ions to exploit their high potential energies for processes such as surface modification. In addition, we show that these offsets can be utilized to estimate the effective radius of the electron beam inside the trap.
Numerical Simulations of the Kinetic Energy Transfer in the Bath of a BOF Converter
NASA Astrophysics Data System (ADS)
Zhou, Xiaobin; Ersson, Mikael; Zhong, Liangcai; Jönsson, Pär
2016-02-01
The paper focuses on the fundamental aspects of the kinetic energy transfer from a top and bottom gas injection to the bath of the basic oxygen furnace (BOF) by applying a mathematical model. The analyses revealed that the energy transfer is less efficient when top lance height is lowered or the flowrate is increased in the top blowing operations. However, an inverse trend was found that the kinetic energy transfer is increased when the bottom flowrate is increased for the current bottom blowing operation conditions. The kinetic energy transfer index results indicated that the energy transfer for the bottom blowing is much more efficient than that of the top blowing operations. To understand the effects of the upper buoyant phase on the energy dissipation of the bulk liquid in the bath, different mass and physical properties of slag and foam were considered in the bottom blowing simulations. The slag on top of the bath is found to dissipate by 6.6, 9.4, and 11.2 pct for slag mass values of 5, 9, and 15 t compared to the case without slag atop the surface of the bath, respectively. The results showed that the kinetic energy transfer is not largely influenced by the viscosity of the upper slag or the foaming phases.
Tropical cyclone kinetic energy and structure evolution in the HWRFx model
NASA Astrophysics Data System (ADS)
Maclay, Katherine S.
2011-07-01
Tropical cyclones exhibit significant variability in their structure, especially in terms of size and asymmetric structures. The variations can influence subsequent evolution in the storm as well as its environmental impacts and play an important role in forecasting. This study uses the Hurricane Weather Research and Forecasting Experimental System (HWRFx) to investigate the horizontal and vertical structure of tropical cyclones. Five real data HWRFx model simulations from the 2005 Atlantic tropical cyclone season (two of Hurricanes Emily and Wilma, and one of Hurricane Katrina) are used. Horizontal structure is investigated via several methods: the decomposition of the integrated kinetic energy field into wavenumber space, composite analysis of the wind fields, and azimuthal wavenumber decomposition of the tangential wind field. Additionally, a spatial and temporal decomposition of the vorticity field to study the vortex Rossby wave contribution to storm asymmetries with an emphasis on azimuthal wavenumber-2 features is completed. Spectral decomposition shows that the average low level kinetic energy in azimuthal wavenumbers 0, 1 and 2 are 92%, 6%, and 1.5% of the total kinetic energy. The kinetic energy in higher wavenumbers is much smaller. Analysis also shows that the low level kinetic energy wavenumber 1 and 2 components can vary between 0.3--36.3% and 0.1--14.1% of the total kinetic energy, respectively. The asymmetries associated with storm motion, environmental shear, and the relative orientation of these vectors are examined. A composite analysis shows a dominant wavenumber-1 asymmetry associated with the storm motion and shear vectors. For storm motion the asymmetry is located in the right front quadrant relative to the motion vector with a magnitude exceeding 2.5 m/s, and for shear the asymmetry is located 90° left of the shear vector with a magnitude exceeding 5 m/s. The locations of these wavenumber-1 asymmetries are consistent with the findings of
Self-powered water splitting using flowing kinetic energy.
Tang, Wei; Han, Yu; Han, Chang Bao; Gao, Cai Zhen; Cao, Xia; Wang, Zhong Lin
2015-01-14
By utilizing a water-flow-driven triboelectric nanogenerator, a fully self-powered water-splitting process is demonstrated using the electricity converted from a water flow without additional energy costs. Considering the extremely low costs, the demonstrated approach is universally applicable and practically usable for future water electrolysis, which may initiate a research direction in the field of triboelectrolysis and possibly impacts energy science in general. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Simultaneous computation of free energies and kinetics of rare events
NASA Astrophysics Data System (ADS)
Moroni, Daniele; van Erp, Titus S.; Bolhuis, Peter G.
2005-05-01
We introduce a method to evaluate simultaneously the reaction rate constant and the free energy profile of a process in a complex environment. The method employs the partial path transition interface sampling technique we recently developed for the calculation of rate constants in diffusive systems. We illustrate the applicability of the technique by studying a simple dimer in a repulsive fluid, and show that the free energy can be obtained at no additional computational cost.
Exact kinetic energy enables accurate evaluation of weak interactions by the FDE-vdW method
Sinha, Debalina; Pavanello, Michele
2015-08-28
The correlation energy of interaction is an elusive and sought-after interaction between molecular systems. By partitioning the response function of the system into subsystem contributions, the Frozen Density Embedding (FDE)-vdW method provides a computationally amenable nonlocal correlation functional based on the adiabatic connection fluctuation dissipation theorem applied to subsystem density functional theory. In reproducing potential energy surfaces of weakly interacting dimers, we show that FDE-vdW, either employing semilocal or exact nonadditive kinetic energy functionals, is in quantitative agreement with high-accuracy coupled cluster calculations (overall mean unsigned error of 0.5 kcal/mol). When employing the exact kinetic energy (which we term the Kohn-Sham (KS)-vdW method), the binding energies are generally closer to the benchmark, and the energy surfaces are also smoother.
Exact kinetic energy enables accurate evaluation of weak interactions by the FDE-vdW method.
Sinha, Debalina; Pavanello, Michele
2015-08-28
The correlation energy of interaction is an elusive and sought-after interaction between molecular systems. By partitioning the response function of the system into subsystem contributions, the Frozen Density Embedding (FDE)-vdW method provides a computationally amenable nonlocal correlation functional based on the adiabatic connection fluctuation dissipation theorem applied to subsystem density functional theory. In reproducing potential energy surfaces of weakly interacting dimers, we show that FDE-vdW, either employing semilocal or exact nonadditive kinetic energy functionals, is in quantitative agreement with high-accuracy coupled cluster calculations (overall mean unsigned error of 0.5 kcal/mol). When employing the exact kinetic energy (which we term the Kohn-Sham (KS)-vdW method), the binding energies are generally closer to the benchmark, and the energy surfaces are also smoother.
Exact kinetic energy enables accurate evaluation of weak interactions by the FDE-vdW method
NASA Astrophysics Data System (ADS)
Sinha, Debalina; Pavanello, Michele
2015-08-01
The correlation energy of interaction is an elusive and sought-after interaction between molecular systems. By partitioning the response function of the system into subsystem contributions, the Frozen Density Embedding (FDE)-vdW method provides a computationally amenable nonlocal correlation functional based on the adiabatic connection fluctuation dissipation theorem applied to subsystem density functional theory. In reproducing potential energy surfaces of weakly interacting dimers, we show that FDE-vdW, either employing semilocal or exact nonadditive kinetic energy functionals, is in quantitative agreement with high-accuracy coupled cluster calculations (overall mean unsigned error of 0.5 kcal/mol). When employing the exact kinetic energy (which we term the Kohn-Sham (KS)-vdW method), the binding energies are generally closer to the benchmark, and the energy surfaces are also smoother.
Makwana, K. D.; Zhdankin, V.; Li, H.; Daughton, W.; Cattaneo, F.
2015-04-10
We performed simulations of decaying magnetohydrodynamic (MHD) turbulence with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k-1.3⊥k⊥-1.3. The kinetic code shows a spectral slope of k-1.5⊥k⊥-1.5 for smaller simulation domain, and k-1.3⊥k⊥-1.3 for larger domain. We then estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. Finally, this work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.
Makwana, K. D.; Zhdankin, V.; Li, H.; ...
2015-04-10
We performed simulations of decaying magnetohydrodynamic (MHD) turbulence with a fluid and a kinetic code. The initial condition is an ensemble of long-wavelength, counter-propagating, shear-Alfvén waves, which interact and rapidly generate strong MHD turbulence. The total energy is conserved and the rate of turbulent energy decay is very similar in both codes, although the fluid code has numerical dissipation, whereas the kinetic code has kinetic dissipation. The inertial range power spectrum index is similar in both the codes. The fluid code shows a perpendicular wavenumber spectral slope of k-1.3⊥k⊥-1.3. The kinetic code shows a spectral slope of k-1.5⊥k⊥-1.5 for smallermore » simulation domain, and k-1.3⊥k⊥-1.3 for larger domain. We then estimate that collisionless damping mechanisms in the kinetic code can account for the dissipation of the observed nonlinear energy cascade. Current sheets are geometrically characterized. Their lengths and widths are in good agreement between the two codes. The length scales linearly with the driving scale of the turbulence. In the fluid code, their thickness is determined by the grid resolution as there is no explicit diffusivity. In the kinetic code, their thickness is very close to the skin-depth, irrespective of the grid resolution. Finally, this work shows that kinetic codes can reproduce the MHD inertial range dynamics at large scales, while at the same time capturing important kinetic physics at small scales.« less
Connecting the kinetics and energy landscape of tRNA translocation on the ribosome.
Whitford, Paul C; Blanchard, Scott C; Cate, Jamie H D; Sanbonmatsu, Karissa Y
2013-01-01
Functional rearrangements in biomolecular assemblies result from diffusion across an underlying energy landscape. While bulk kinetic measurements rely on discrete state-like approximations to the energy landscape, single-molecule methods can project the free energy onto specific coordinates. With measures of the diffusion, one may establish a quantitative bridge between state-like kinetic measurements and the continuous energy landscape. We used an all-atom molecular dynamics simulation of the 70S ribosome (2.1 million atoms; 1.3 microseconds) to provide this bridge for specific conformational events associated with the process of tRNA translocation. Starting from a pre-translocation configuration, we identified sets of residues that collectively undergo rotary rearrangements implicated in ribosome function. Estimates of the diffusion coefficients along these collective coordinates for translocation were then used to interconvert between experimental rates and measures of the energy landscape. This analysis, in conjunction with previously reported experimental rates of translocation, provides an upper-bound estimate of the free-energy barriers associated with translocation. While this analysis was performed for a particular kinetic scheme of translocation, the quantitative framework is general and may be applied to energetic and kinetic descriptions that include any number of intermediates and transition states.
NASA Technical Reports Server (NTRS)
Browning, P. A.; Fuelberg, H. E.
1983-01-01
Divergent and rotational components of the synoptic scale kinetic energy balance are presented using rawinsonde data at 3 and 6 h intervals from the Atmospheric Variability Experiment (AVE 4). Two intense thunderstorm complexes occurred during the period. Energy budgets are described for the entire computational region and for limited volumes that enclose and move with the convection. Although small in magnitude, the divergent wind component played an important role in the cross contour generation and horizontal flux divergence of kinetic energy. The importance of V sub D appears directly to the presence and intensity of convection within the area. Although K sub D usually comprised less than 10 percent of the total kinetic energy content within the storm environment, as much as 87 percent of the total horizontal flux divergence and 68 percent of the total cross contour generation was due to the divergent component in the upper atmosphere. Generation of kinetic energy by the divergent component appears to be a major factor in the creation of an upper level wind maximum on the poleward side of one of the complexes. A random error analysis is presented to assess confidence limits in the various energy parameters.
Properties of the kinetic energy budgets in wall-bounded turbulent flows
NASA Astrophysics Data System (ADS)
Zhou, Ang; Klewicki, Joseph
2016-08-01
Available high-quality numerical simulation data are used to investigate and characterize the kinetic energy budgets for fully developed turbulent flow in pipes and channels, and in the zero-pressure gradient turbulent boundary layer. The mean kinetic energy equation in these flows is empirically and analytically shown to respectively exhibit the same four-layer leading-order balance structure as the mean momentum equation. This property of the mean kinetic energy budget provides guidance on how to group terms in the more complicated turbulence and total kinetic energy budgets. Under the suggested grouping, the turbulence budget shows either a two- or three-layer structure (depending on channel or pipe versus boundary layer flow), while the total kinetic energy budget exhibits a clear four-layer structure. These layers, however, differ in position and size and exhibit variations with friction Reynolds number (δ+) that are distinct from the layer structure associated with the mean dynamics. The present analyses indicate that each of the four layers is characterized by a predominance of a reduced set of the grouped terms in the governing equation. The width of the third layer is mathematically reasoned to scale like δ+-√{δ+} at finite Reynolds numbers. In the boundary layer the upper bounds of both the second and third layers convincingly merge under this normalization, as does the width of the third layer. This normalization also seems to be valid for the width of the third layer in pipes and channels, but only for δ+>1000 . The leading-order balances in the total kinetic energy budget are shown to arise from a nontrivial interweaving of the mean and turbulence budget contributions with distance from the wall.
[Responses of biological soil crust to and its relief effect on raindrop kinetic energy].
Qin, Ning-qiang; Zhao, Yun-ge
2011-09-01
Based on the field investigation and by the method of simulated single-drop rain, this paper studied the responses of different types of biological soil crusts (biocrusts) in the wind-water erosion interleaving region of Loess Plateau to and their relief effect on the kinetic energy of raindrops. The responses of the biocrusts to raindrop kinetic energy had close relations with their biological composition. The cyanobacteria-dominated biocrusts with a thickness of 1 cm and the moss-dominated biocrusts with the coverage of 80% could resist in 0.99 J and 75.56 J of cumulative rain drop kinetic energy, respectively, and the potential resistance of the biocrusts with the same biological compositions was relative to the biomass of the biological compositions, i.e., the larger the biomass, the higher the resistance. As the chlorophyll a content of cyanobacteria- dominated biocrusts (which characterizes the cyanobacterial biomass) increased from 3.32 to 3.73 microg x g(-1), the resistance of the biocrusts against the cumulative raindrop kinetic energy increased from 0.99 to 2.17 J; when the moss biomass in the moss- dominated biocrusts increased from 2.03 to 4.73 g x dm(-2), the resistance of the crusts increased from 6.08 to 75.56 J. During the succession of the biocrusts, their responses to the raindrop kinetic energy presented an "S" pattern. No significant differences in the resistance against raindrop cumulative kinetic energy were observed between the cyanobacteria-dominated biocrusts with variable biomass, but the resistance of moss-dominated biocrusts increased significantly as their biomass per unit area increased. The resistance of moss-dominated biocrusts increased linearly when their biomass increased from 2.03 g x dm(-2) to 4.73 g x dm(-2). The moss-dominated biocrusts could resist in 62.03 J of raindrop kinetic energy when their biomass was up to 3.70 g x dm(-2). Biocrusts had obvious effects in relieving raindrop kinetic energy, and the relief effect
Energy-Driven Kinetic Monte Carlo Method and Its Application in Fullerene Coalescence.
Ding, Feng; Yakobson, Boris I
2014-09-04
Mimicking the conventional barrier-based kinetic Monte Carlo simulation, an energy-driven kinetic Monte Carlo (EDKMC) method was developed to study the structural transformation of carbon nanomaterials. The new method is many orders magnitude faster than standard molecular dynamics or Monte Marlo (MC) simulations and thus allows us to explore rare events within a reasonable computational time. As an example, the temperature dependence of fullerene coalescence was studied. The simulation, for the first time, revealed that short capped single-walled carbon nanotubes (SWNTs) appear as low-energy metastable structures during the structural evolution.
Banerjee, Kinshuk; Das, Biswajit; Gangopadhyay, Gautam
2013-04-28
In this paper, we have explored generic criteria of cooperative behavior in ion channel kinetics treating it on the same footing with multistate receptor-ligand binding in a compact theoretical framework. We have shown that the characterization of cooperativity of ion channels in terms of the Hill coefficient violates the standard Hill criteria defined for allosteric cooperativity of ligand binding. To resolve the issue, an alternative measure of cooperativity is proposed here in terms of the cooperativity index that sets a unified criteria for both the systems. More importantly, for ion channel this index can be very useful to describe the cooperative kinetics as it can be readily determined from the experimentally measured ionic current combined with theoretical modelling. We have analyzed the correlation between the voltage value and slope of the voltage-activation curve at the half-activation point and consequently determined the standard free energy of activation of the ion channel using two well-established mechanisms of cooperativity, namely, Koshland-Nemethy-Filmer (KNF) and Monod-Wyman-Changeux (MWC) models. Comparison of the theoretical results for both the models with appropriate experimental data of mutational perturbation of Shaker K(+) channel supports the experimental fact that the KNF model is more suitable to describe the cooperative behavior of this class of ion channels, whereas the performance of the MWC model is unsatisfactory. We have also estimated the mechanistic performance through standard free energy of channel activation for both the models and proposed a possible functional disadvantage in the MWC scheme.
Bio-kinetic energy harvesting using electroactive polymers
NASA Astrophysics Data System (ADS)
Slade, Jeremiah R.; Bowman, Jeremy; Kornbluh, Roy
2012-06-01
In hybrid vehicles, electric motors are used on each wheel to not only propel the car but also to decelerate the car by acting as generators. In the case of the human body, muscles spend about half of their time acting as a brake, absorbing energy, or doing what is known as negative work. Using dielectric elastomers it is possible to use the "braking" phases of walking to generate power without restricting or fatiguing the Warfighter. Infoscitex and SRI have developed and demonstrated methods for using electroactive polymers (EAPs) to tap into the negative work generated at the knee during the deceleration phase of the human gait cycle and convert it into electrical power that can be used to support wearable information systems, including display and communication technologies. The specific class of EAP that has been selected for these applications is termed dielectric elastomers. Because dielectric elastomers dissipate very little mechanical energy into heat, greater amounts of energy can be converted into electricity than by any other method. The long term vision of this concept is to have EAP energy harvesting cells located in components of the Warfighter ensemble, such as the boot uppers, knee pads and eventually even the clothing itself. By properly locating EAPs at these sites it will be possible to not only harvest power from the negative work phase but to actually reduce the amount of work done by the Warfighter's muscles during this phase, thereby reducing fatigue and minimizing the forces transmitted to the joints.
Flywheel set for accumulating kinetic energy of rotation
Theyse, F.H.
1980-09-16
A flywheel set is described for accumulating energy with elastically supported bearings, resulting in a low critical speed, lying at all times under the operational flywheel speed. The axial thrust taking bearings, or one bearing, may be operating with magnetic forces.
Influence of the Richtmyer-Meshkov instability on the kinetic energy spectrum.
Weber, Christopher R.
2010-09-01
The fluctuating kinetic energy spectrum in the region near the Richtmyer-Meshkov instability (RMI) is experimentally investigated using particle image velocimetry (PIV). The velocity field is measured at a high spatial resolution in the light gas to observe the effects of turbulence production and dissipation. It is found that the RMI acts as a source of turbulence production near the unstable interface, where energy is transferred from the scales of the perturbation to smaller scales until dissipation. The interface also has an effect on the kinetic energy spectrum farther away by means of the distorted reflected shock wave. The energy spectrum far from the interface initially has a higher energy content than that of similar experiments with a flat interface. These differences are quick to disappear as dissipation dominates the flow far from the interface.
Time-of-flight electron spectrometer for a broad range of kinetic energies
Kothe, Alexander; Metje, Jan; Wilke, Martin; Moguilevski, Alexandre; Engel, Nicholas; Al-Obaidi, Ruba; Richter, Clemens; Golnak, Ronny; Kiyan, Igor Yu.; Aziz, Emad F.
2013-02-15
A newly constructed time-of-flight electron spectrometer of the magnetic bottle type is characterized for electron detection in a broad range of kinetic energies. The instrument is designed to measure the energy spectra of electrons generated from liquids excited by strong laser fields and photons in the range of extreme ultra violet and soft X-rays. Argon inner shell electrons were recorded to calibrate the spectrometer and investigate its characteristics, such as energy resolution and collection efficiency. Its energy resolution {Delta}E/E of 1.6% allows resolving the Ar 2p spin orbit structure at kinetic energies higher than 100 eV. The collection efficiency is determined and compared to that of the spectrometer in its field-free configuration.
Time-of-flight electron spectrometer for a broad range of kinetic energies.
Kothe, Alexander; Metje, Jan; Wilke, Martin; Moguilevski, Alexandre; Engel, Nicholas; Al-Obaidi, Ruba; Richter, Clemens; Golnak, Ronny; Kiyan, Igor Yu; Aziz, Emad F
2013-02-01
A newly constructed time-of-flight electron spectrometer of the magnetic bottle type is characterized for electron detection in a broad range of kinetic energies. The instrument is designed to measure the energy spectra of electrons generated from liquids excited by strong laser fields and photons in the range of extreme ultra violet and soft X-rays. Argon inner shell electrons were recorded to calibrate the spectrometer and investigate its characteristics, such as energy resolution and collection efficiency. Its energy resolution ΔE/E of 1.6% allows resolving the Ar 2p spin orbit structure at kinetic energies higher than 100 eV. The collection efficiency is determined and compared to that of the spectrometer in its field-free configuration.
Concept of variable activation energy and its validity in nonisothermal kinetics.
Tan, Guanglei; Wang, Qi; Zheng, Hongxia; Zhao, Wei; Zhang, Song; Liu, Zhongsuo
2011-06-09
The concept of variable activation energy in solid-state kinetics under nonisothermal conditions has been suffering from doubt and controversy. Rate equations of nonisothermal kinetics of solid decomposition, which involve the factors of thermodynamics conditions, pressure of gaseous product, structure parameters of solid, and/or extent of conversion, are derived from the models of the interface reaction, the diffusion of gaseous product, and the nuclei growth of the solid product, respectively. The definition of the validity function in the rate equations represents the influence of the factors on the reaction rate. A function of variable activation energy depending on the validity function is also developed. The changing trend and degree of activation energy are extrapolated from the function of variable activation energy and based on the data of nonisothermal thermal decomposition of calcium carbonate. It is shown that the concept of variable activation energy is meaningfully applicable to solid-state reactions under nonisothermal conditions.
Magnetic to magnetic and kinetic to magnetic energy transfers at the top of the Earth's core
NASA Astrophysics Data System (ADS)
Huguet, Ludovic; Amit, Hagay; Alboussière, Thierry
2016-11-01
We develop the theory for the magnetic to magnetic and kinetic to magnetic energy transfer between different spherical harmonic degrees due to the interaction of fluid flow and radial magnetic field at the top of the Earth's core. We show that non-zero secular variation of the total magnetic energy could be significant and may provide evidence for the existence of stretching secular variation, which suggests the existence of radial motions at the top of the Earth's core-whole core convection or MAC waves. However, the uncertainties of the small scales of the geomagnetic field prevent a definite conclusion. Combining core field and flow models we calculate the detailed magnetic to magnetic and kinetic to magnetic energy transfer matrices. The magnetic to magnetic energy transfer shows a complex behaviour with local and non-local transfers. The spectra of magnetic to magnetic energy transfers show clear maxima and minima, suggesting an energy cascade. The kinetic to magnetic energy transfers, which are much weaker due to the weak poloidal flow, are either local or non-local between degree one and higher degrees. The patterns observed in the matrices resemble energy transfer patterns that are typically found in 3-D MHD numerical simulations.
Weijers, Mireille; Barneveld, Peter A.; Cohen Stuart, Martien A.; Visschers, Ronald W.
2003-01-01
The heat-induced denaturation kinetics of two different sources of ovalbumin at pH 7 was studied by chromatography and differential scanning calorimetry. The kinetics was found to be independent of protein concentration and salt concentration, but was strongly dependent on temperature. For highly pure ovalbumin, the decrease in nondenatured native protein showed first-order dependence. The activation energy obtained with different techniques varied between 430 and 490 kJ•mole−1. First-order behavior was studied in detail using differential scanning calorimetry. The calorimetric traces were irreversible and highly scan rate-dependent. The shape of the thermograms as well as the scan rate dependence can be explained by assuming that the thermal denaturation takes place according to a simplified kinetic process \\documentclass[10pt]{article} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{pmc} \\usepackage[Euler]{upgreek} \\pagestyle{empty} \\oddsidemargin -1.0in \\begin{document} \\begin{equation*}N\\;{ \\,\\substack{ ^{{\\mathit{k}}} \\\\ {\\rightarrow} \\\\ }\\, }\\;D\\end{equation*}\\end{document} where N is the native state, D is denatured (or another final state) and k a first-order kinetic constant that changes with temperature, according to the Arrhenius equation. A kinetic model for the temperature-induced denaturation and aggregation of ovalbumin is presented. Commercially obtained ovalbumin was found to contain an intermediate-stable fraction (IS) of about 20% that was unable to form aggregates. The denaturation of this fraction did not satisfy first-order kinetics. PMID:14627731
NASA Technical Reports Server (NTRS)
Han, Jongil; Arya, S. Pal; Shaohua, Shen; Lin, Yuh-Lang; Proctor, Fred H. (Technical Monitor)
2000-01-01
Algorithms are developed to extract atmospheric boundary layer profiles for turbulence kinetic energy (TKE) and energy dissipation rate (EDR), with data from a meteorological tower as input. The profiles are based on similarity theory and scalings for the atmospheric boundary layer. The calculated profiles of EDR and TKE are required to match the observed values at 5 and 40 m. The algorithms are coded for operational use and yield plausible profiles over the diurnal variation of the atmospheric boundary layer.
NASA Astrophysics Data System (ADS)
Cadei, Andrea; Dionisi, Alessandro; Sardini, Emilio; Serpelloni, Mauro
2014-01-01
Implantable medical devices usually require a battery to operate and this can represent a severe restriction. In most cases, the implantable medical devices must be surgically replaced because of the dead batteries; therefore, the longevity of the whole implantable medical device is determined by the battery lifespan. For this reason, researchers have been studying energy harvesting techniques from the human body in order to obtain batteryless implantable medical devices. The human body is a rich source of energy and this energy can be harvested from body heat, breathing, arm motion, leg motion or the motion of other body parts produced during walking or any other activity. In particular, the main human-body energy sources are kinetic energy and thermal energy. This paper reviews the state-of-art in kinetic and thermoelectric energy harvesters for powering implantable medical devices. Kinetic energy harvesters are based on electromagnetic, electrostatic and piezoelectric conversion. The different energy harvesters are analyzed highlighting their sizes, energy or power they produce and their relative applications. As they must be implanted, energy harvesting devices must be limited in size, typically about 1 cm3. The available energy depends on human-body positions; therefore, some positions are more advantageous than others. For example, favorable positions for piezoelectric harvesters are hip, knee and ankle where forces are significant. The energy harvesters here reported produce a power between 6 nW and 7.2 mW; these values are comparable with the supply requirements of the most common implantable medical devices; this demonstrates that energy harvesting techniques is a valid solution to design batteryless implantable medical devices.
Materials implications of advanced thermal and kinetic energy threats
NASA Astrophysics Data System (ADS)
Fitpatrick, R.; Mescall, J.
1983-05-01
The behavior of materials subjected to laser radiation rather than issues of target acquisition, pointing and tracking, fire control, and damage recognition are discussed. These target acquisition and fire control requirements represents extremely difficult technological problems that must be solved if the Laser is ever to be used as a weapon against hard targets. Questions that must be resolved are outlined as follows: Can laser beams be propagated over large distances along predictable paths? Can available active and passive countermeasures be overcome? Is there a place for large scale, high power, high value directed energy weapons on the battlefield? While these questions are being addressed, the Army materials community is developing a data base on materials and structures vulnerability. This data base will not only serve the hardening community, which has the task of offering protection against directed energy, but also will help the weapon developers determine the effectiveness of their systems.
Energy transfer and dual cascade in kinetic magnetized plasma turbulence.
Plunk, G G; Tatsuno, T
2011-04-22
The question of how nonlinear interactions redistribute the energy of fluctuations across available degrees of freedom is of fundamental importance in the study of turbulence and transport in magnetized weakly collisional plasmas, ranging from space settings to fusion devices. In this Letter, we present a theory for the dual cascade found in such plasmas, which predicts a range of new behavior that distinguishes this cascade from that of neutral fluid turbulence. These phenomena are explained in terms of the constrained nature of spectral transfer in nonlinear gyrokinetics. Accompanying this theory are the first observations of these phenomena, obtained via direct numerical simulations using the gyrokinetic code AstroGK. The basic mechanisms that are found provide a framework for understanding the turbulent energy transfer that couples scales both locally and nonlocally.
Kinetic Energy associated with Dynamic Fragmentation in Brittle Solids
NASA Astrophysics Data System (ADS)
Griffith, W. A.; Ghaffari, H.; Barber, T. J.
2016-12-01
The formation of fragments during dynamic processes associated with impulsive loads has been the subject of numerous studies ranging from shaped-charge jet break up and rock blasting to bolide impacts, and, more recently, earthquake rupture. In the latter case pulverized rocks found millimeters to tens of meters from the principal slip zone have been associated with fast, and even supershear, rupture. It has been conjectured that the transition from intact or discretely fractured host rock to pulverization is controlled by initial micro-defects and the driven impulse signal characteristics. Here we report a series of experiments where we characterize the 3D terminal velocity vectors of particles in a range of fragmented to pulverized Novaculite and Westerly Granite rock samples using a Split Hopkinson Pressure Bar Apparatus. We accomplish this by controlling the rate of the stress ramp (a characteristic of the source time function) applied to the rock specimen and recording the impact pattern of rock fragments using a steel ring lined with a pressure-calibrated thin film surrounding the specimen. Using elastic Hertzian contact theory in conjunction with the resulting pressure distributions, we calculate the velocity of ejected particles for each experiment, allowing us to calculate approximate the normal components of kinematic energy of flying fragments. In combination with the laser particle size analysis (PSD), we show a relationship between the rate of the stress ramp and average particle size, and we refine the estimation of fracture energy during the experiments. Coupled with recently obtained data constraining the mechanical energy invested in creating new fracture surfaces, this work brings us closer to defining a complete energy budget for the brittle fragmentation process during earthquake rupture.
Energy analysis of convectively induced wind perturbations
NASA Technical Reports Server (NTRS)
Fuelberg, Henry E.; Buechler, Dennis E.
1989-01-01
Budgets of divergent and rotational components of kinetic energy (KD and KR) are examined for four upper level wind speed maxima that develop during the fourth Atmospheric Variability Experiment (AVE IV) and the first AVE-Severe Environmental Storms and Mesoscale Experiment (AVE-SESAME I). A similar budget analysis is performed for a low-level jet stream during AVE-SESAME I. The energetics of the four upper level speed maxima is found to have several similarities. The dominant source of KD is cross-contour flow by the divergent wind, and KD provides a major source of KR via a conversion process. Conversion from available potential energy provides an additional source of KR in three of the cases. Horizontal maps reveal that the conversions involving KD are maximized in regions poleward of the convection. Low-level jet development during AVE-SESAME I appears to be assisted by convective activity to the west.
Simulations of thermodynamics and kinetics on rough energy landscapes with milestoning.
Bello-Rivas, Juan M; Elber, Ron
2016-03-05
We investigated by computational means the kinetics and stationary behavior of stochastic dynamics on an ensemble of rough two-dimensional energy landscapes. There are no obvious separations of temporal scales in these systems, which constitute a simple model for the behavior of glasses and some biomaterials. Even though there are significant computational challenges present in these systems due to the large number of metastable states, the Milestoning method is able to compute their kinetic and thermodynamic properties exactly. We observe two clearly distinguished regimes in the overall kinetics: one in which diffusive behavior dominates and another that follows an Arrhenius law (despite the absence of a dominant barrier). We compare our results with those obtained with an exactly-solvable one-dimensional model, and with the results from the rough one-dimensional energy model introduced by Zwanzig. © 2015 Wiley Periodicals, Inc.
Simulations of thermodynamics and kinetics on rough energy landscapes with Milestoning
Bello-Rivas, Juan M.; Elber, Ron
2015-01-01
We investigated by computational means the kinetics and stationary behavior of stochastic dynamics on an ensemble of rough two-dimensional energy landscapes. There are no obvious separations of temporal scales in these systems, which constitute a simple model for the behavior of glasses and some biomaterials. Even though there are significant computational challenges present in these systems due to the large number of metastable states, the Milestoning method is able to compute their kinetic and thermodynamic properties exactly. We observe two clearly distinguished regimes in the overall kinetics: one in which diffusive behavior dominates and another that follows an Arrhenius law (despite the absence of a dominant barrier). We compare our results with those obtained with an exactly-solvable one-dimensional model, and with the results from the rough one-dimensional energy model introduced by Zwanzig. PMID:26265358
Plasmon-induced resonance energy transfer for solar energy conversion
NASA Astrophysics Data System (ADS)
Li, Jiangtian; Cushing, Scott K.; Meng, Fanke; Senty, Tess R.; Bristow, Alan D.; Wu, Nianqiang
2015-09-01
In Förster resonance energy transfer (FRET), energy non-radiatively transfers from a blue-shifted emitter to a red-shifted absorber by dipole-dipole coupling. This study shows that plasmonics enables the opposite transfer direction, transferring the plasmonic energy towards the short-wavelength direction to induce charge separation in a semiconductor. Plasmon-induced resonance energy transfer (PIRET) differs from FRET because of the lack of a Stoke's shift, non-local absorption effects and a strong dependence on the plasmon's dephasing rate and dipole moment. PIRET non-radiatively transfers energy through an insulating spacer layer, which prevents interfacial charge recombination losses and dephasing of the plasmon from hot-electron transfer. The distance dependence of dipole-dipole coupling is mapped out for a range of detuning across the plasmon resonance. PIRET can efficiently harvest visible and near-infrared sunlight with energy below the semiconductor band edge to help overcome the constraints of band-edge energetics for single semiconductors in photoelectrochemical cells, photocatalysts and photovoltaics.
Kinetic reconstruction of the free-energy landscape.
Wedekind, Jan; Reguera, David
2008-09-04
We present a new general method to trace back a lot of valuable information from direct simulations and experiments of activated processes. In particular, it allows the reconstruction of the free-energy landscape for an arbitrary reaction coordinate directly from the out-of-equilibrium dynamics of the process. We demonstrate the power of this concept by its application to a molecular dynamics simulation of nucleation of a Lennard-Jones vapor. The same method can be also applied to Brownian dynamics and stochastic simulations.
Skin penetration assessment of less lethal kinetic energy munitions.
Bir, Cynthia A; Stewart, Shelby J; Wilhelm, Marianne
2005-11-01
The development of less-lethal technologies has provided law enforcement personnel with an alternative to lethal force. Although the less lethal projectile was produced to engender non-penetrating wounds, case studies show that there have been a number of reported penetrating injuries ranging from minor to significant in morbidity. The objective of this study was to determine the energy per unit area required to penetrate various regions of the body. Eight unembalmed postmortem human specimens were procured for this testing. Each specimen sustained a maximum of 25 impacts consisting of shots to the anterior and posterior thorax, abdomen, and legs. A 12-gauge, fin-stabilized, rubber rocket round was used as the impactor for all of the conducted tests. The energy density required for 50% risk of penetration varied from 23.99 J/cm2 for the location on the anterior rib (p = 0.000) to 52.74 J/cm2 for the location on the posterior rib (p = 0.001).
The influence of energy migration on luminescence kinetics parameters in upconversion nanoparticles
NASA Astrophysics Data System (ADS)
Alyatkin, Sergey; Asharchuk, Ilya; Khaydukov, Kirill; Nechaev, Andrey; Lebedev, Oleg; Vainer, Yuri; Semchishen, Vladimir; Khaydukov, Evgeny
2017-01-01
The mechanism of upconversion at the nanoscale is still under discussion. In this paper, we report on the experimental results of anti-Stokes luminescence kinetics in the upconversion nanoparticles of β-NaYF4: 20%Yb3+; 0.6%Tm3+. The parameters of the luminescence kinetics were found to be unambiguously dependent on the number of excitation quanta n, which are necessary for certain transitions between the energy states of thulium ions. The observed correlation has been explained by means of the long-lasting energy migration between the ytterbium ions. The spread in time between the luminescent maxima of the corresponding thulium transitions not only shows the nonlinear character of upconversion, but also reveals the time scale of energy migration as well. From these, we derive that the conventional Förster formalism applied to the estimation of energy transfer efficiency in UCNP-fluorophore pairs can provide misleading results.
Kinetic-energy matrix elements for atomic Hylleraas-CI wave functions.
Harris, Frank E
2016-05-28
Hylleraas-CI is a superposition-of-configurations method in which each configuration is constructed from a Slater-type orbital (STO) product to which is appended (linearly) at most one interelectron distance rij. Computations of the kinetic energy for atoms by this method have been difficult due to the lack of formulas expressing these matrix elements for general angular momentum in terms of overlap and potential-energy integrals. It is shown here that a strategic application of angular-momentum theory, including the use of vector spherical harmonics, enables the reduction of all atomic kinetic-energy integrals to overlap and potential-energy matrix elements. The new formulas are validated by showing that they yield correct results for a large number of integrals published by other investigators.
Kinetic Energy from Supernova Feedback in High-resolution Galaxy Simulations
NASA Astrophysics Data System (ADS)
Simpson, Christine M.; Bryan, Greg L.; Hummels, Cameron; Ostriker, Jeremiah P.
2015-08-01
We describe a new method for adding a prescribed amount of kinetic energy to simulated gas modeled on a cartesian grid by directly altering grid cells’ mass and velocity in a distributed fashion. The method is explored in the context of supernova (SN) feedback in high-resolution (˜10 pc) hydrodynamic simulations of galaxy formation. Resolution dependence is a primary consideration in our application of the method, and simulations of isolated explosions (performed at different resolutions) motivate a resolution-dependent scaling for the injected fraction of kinetic energy that we apply in cosmological simulations of a 109 M⊙ dwarf halo. We find that in high-density media (≳50 cm-3) with coarse resolution (≳4 pc per cell), results are sensitive to the initial kinetic energy fraction due to early and rapid cooling. In our galaxy simulations, the deposition of small amounts of SN energy in kinetic form (as little as 1%) has a dramatic impact on the evolution of the system, resulting in an order-of-magnitude suppression of stellar mass. The overall behavior of the galaxy in the two highest resolution simulations we perform appears to converge. We discuss the resulting distribution of stellar metallicities, an observable sensitive to galactic wind properties, and find that while the new method demonstrates increased agreement with observed systems, significant discrepancies remain, likely due to simplistic assumptions that neglect contributions from SNe Ia and stellar winds.
Similarity between turbulent kinetic energy and temperature spectra in the near-wall region
NASA Technical Reports Server (NTRS)
Antonia, R. A.; Kim, J.
1991-01-01
The similarity between turbulent kinetic energy and temperature spectra, previously confirmed using experimental data in various turbulent shear flows, is validated in the near-wall region using direct numerical simulation data in a fully developed turbulent channel flow. The dependence of this similarity on the molecular Prandtl number is also examined.
Zou, Jiaxiu; Peng, Xiaolan; Li, Miao; Xiong, Ying; Wang, Bing; Dong, Faqin; Wang, Bin
2017-03-01
In the present study, the electrochemical oxidation of real wastewaters discharged by textile industry was carried out using a boron-doped diamond (BDD) anode. The effect of operational variables, such as applied current density (20-100 mA·cm(-2)), NaCl concentration added to the real wastewaters (0-3 g·L(-1)), and pH value (2.0-10.0), on the kinetics of COD oxidation and on the energy consumption was carefully investigated. The obtained experimental results could be well matched with a proposed kinetic model, in which the indirect oxidation mediated by electrogenerated strong oxidants would be described through a pseudo-first-order kinetic constant k. Values of k exhibited a linear increase with increasing applied current density and decreasing pH value, and an exponential increase with NaCl concentration. Furthermore, high oxidation kinetics resulted in low specific energy consumption, but this conclusion was not suitable to the results obtained under different applied current density. Under the optimum operational conditions, it only took 3 h to complete remove the COD in the real textile wastewaters and the specific energy consumption could be as low as 11.12 kWh·kg(-1) COD. The obtained results, low energy consumption and short electrolysis time, allowed to conclude that the electrochemical oxidation based on BDD anodes would have practical industrial application for the treatment of real textile wastewater.
Employing Magnetic Levitation to Monitor Reaction Kinetics and Measure Activation Energy
ERIC Educational Resources Information Center
Benz, Lauren; Cesafsky, Karen E.; Le, Tran; Park, Aileen; Malicky, David
2012-01-01
This article describes a simple and inexpensive undergraduate-level kinetics experiment that uses magnetic levitation to monitor the progress and determine the activation energy of a condensation reaction on a polymeric solid support. The method employs a cuvette filled with a paramagnetic solution positioned between two strong magnets. The…
Employing Magnetic Levitation to Monitor Reaction Kinetics and Measure Activation Energy
ERIC Educational Resources Information Center
Benz, Lauren; Cesafsky, Karen E.; Le, Tran; Park, Aileen; Malicky, David
2012-01-01
This article describes a simple and inexpensive undergraduate-level kinetics experiment that uses magnetic levitation to monitor the progress and determine the activation energy of a condensation reaction on a polymeric solid support. The method employs a cuvette filled with a paramagnetic solution positioned between two strong magnets. The…
KINETIC ENERGY FROM SUPERNOVA FEEDBACK IN HIGH-RESOLUTION GALAXY SIMULATIONS
Simpson, Christine M.; Bryan, Greg L.; Ostriker, Jeremiah P.; Hummels, Cameron
2015-08-10
We describe a new method for adding a prescribed amount of kinetic energy to simulated gas modeled on a cartesian grid by directly altering grid cells’ mass and velocity in a distributed fashion. The method is explored in the context of supernova (SN) feedback in high-resolution (∼10 pc) hydrodynamic simulations of galaxy formation. Resolution dependence is a primary consideration in our application of the method, and simulations of isolated explosions (performed at different resolutions) motivate a resolution-dependent scaling for the injected fraction of kinetic energy that we apply in cosmological simulations of a 10{sup 9} M{sub ⊙} dwarf halo. We find that in high-density media (≳50 cm{sup −3}) with coarse resolution (≳4 pc per cell), results are sensitive to the initial kinetic energy fraction due to early and rapid cooling. In our galaxy simulations, the deposition of small amounts of SN energy in kinetic form (as little as 1%) has a dramatic impact on the evolution of the system, resulting in an order-of-magnitude suppression of stellar mass. The overall behavior of the galaxy in the two highest resolution simulations we perform appears to converge. We discuss the resulting distribution of stellar metallicities, an observable sensitive to galactic wind properties, and find that while the new method demonstrates increased agreement with observed systems, significant discrepancies remain, likely due to simplistic assumptions that neglect contributions from SNe Ia and stellar winds.
NASA Technical Reports Server (NTRS)
Liu, Xiao-Feng; Thomas, Flint O.; Nelson, Robert C.
2001-01-01
Turbulence kinetic energy (TKE) is a very important quantity for turbulence modeling and the budget of this quantity in its transport equation can provide insight into the flow physics. Turbulence kinetic energy budget measurements were conducted for a symmetric turbulent wake flow subjected to constant zero, favorable and adverse pressure gradients in year-three of research effort. The purpose of this study is to clarify the flow physics issues underlying the demonstrated influence of pressure gradient on wake development and provide experimental support for turbulence modeling. To ensure the reliability of these notoriously difficult measurements, the experimental procedure was carefully designed on the basis of an uncertainty analysis. Four different approaches, based on an isotropic turbulence assumption, a locally axisymmetric homogeneous turbulence assumption, a semi-isotropy assumption and a forced balance of the TKE equation, were applied for the estimate of the dissipation term. The pressure transport term is obtained from a forced balance of the turbulence kinetic energy equation. This report will present the results of the turbulence kinetic energy budget measurement and discuss their implication on the development of strained turbulent wakes.
NASA Astrophysics Data System (ADS)
Endo, Kazunaka
2016-02-01
In the Auger electron spectra (AES) simulations, we define theoretical modified kinetic energies of AES in the density functional theory (DFT) calculations. The modified kinetic energies correspond to two final-state holes at the ground state and at the transition-state in DFT calculations, respectively. This method is applied to simulate Auger electron spectra (AES) of 2nd periodic atom (Li, Be, B, C, N, O, F)-involving substances (LiF, beryllium, boron, graphite, GaN, SiO2, PTFE) by deMon DFT calculations using the model molecules of the unit cell. Experimental KVV (valence band electrons can fill K-shell core holes or be emitted during KVV-type transitions) AES of the (Li, O) atoms in the substances agree considerably well with simulation of AES obtained with the maximum kinetic energies of the atoms, while, for AES of LiF, and PTFE substance, the experimental F KVV AES is almost in accordance with the spectra from the transitionstate kinetic energy calculations.
Statistical evaporation of rotating clusters. I. Kinetic energy released
NASA Astrophysics Data System (ADS)
Calvo, F.; Parneix, P.
2003-07-01
Unimolecular evaporation in rotating atomic clusters is investigated using phase space theory (PST) and molecular dynamics simulations. The rotational densities of states are calculated in the sphere+atom approximation, and analytical expressions are given for a radial interaction potential with the form -C/rp. The vibrational densities of states are calculated using Monte Carlo simulations, and the average radial potential at finite temperature is obtained using a recent extension of the multiple range random-walk algorithm. These ideas are tested on simple argon clusters modeled with the Lennard-Jones interaction potential, at several excitation energies and angular momenta of the parent cluster. Our results show that PST successfully reproduces the simulation data, not only the average KER but its probability distribution, for dissociations from LJ14, for which the product cluster can effectively be considered as spherical. Even for dissociations from the nonspherical LJ8, simulation results remain very close to the predictions of the statistical theory.
Ehst, D.A.; Hassanein, A.
1996-02-01
Ablation damage to solid targets with high heat flux impulses is generally greater high-energy electron beam heat sources compared to low-energy plasma guns. This sensitivity to incoming particle kinetic energy is explored with computer modelling; a fast-running routine (DESIRE) is developed for initial scoping analysis and is found to be in reasonable agreement with several experiments on graphite and tungsten targets. If tokamak disruptions are characterized by particle energies less than {approximately}1 keV, then we expect plasma guns are a better analogue than electron beams for simulating disruption behavior and testing candidate plasma-facing materials.
Kinetic energies of fragment ions produced by dissociative photoionization of NO
NASA Technical Reports Server (NTRS)
Samson, J. A. R.; Angel, G. C.; Rstgi, O. P.
1985-01-01
The kinetic energies of ions produced by dissociative photoionization of NO have been measured at the discrete resonance lines of He (584A) and Ne (736A), and with undispersed synchrotron radiation. O sup + ions were identified with energies from 0 to approximately 0.5 eV and two groups of N sup + ions one with energy of 0.36 eV and another with energies between 0.9 and 1.5 eV, apparently produced by predissociation of the C sup 3 P 1 and B'1 sigma states respectively.
The Control Based on Internal Average Kinetic Energy in Complex Environment for Multi-robot System
NASA Astrophysics Data System (ADS)
Yang, Mao; Tian, Yantao; Yin, Xianghua
In this paper, reference trajectory is designed according to minimum energy consumed for multi-robot system, which nonlinear programming and cubic spline interpolation are adopted. The control strategy is composed of two levels, which lower-level is simple PD control and the upper-level is based on the internal average kinetic energy for multi-robot system in the complex environment with velocity damping. Simulation tests verify the effectiveness of this control strategy.
NASA Astrophysics Data System (ADS)
Kropotkin, A. P.
2014-07-01
Dynamics of plasma systems in space involves processes of large-scale energy conversion. Like in conventional gas dynamics, the conversion can occur on shocks. However, in collisionless magnetized plasma systems, quite different nonlinear structures may be responsible for energy conversion. Those are anisotropic kinetic current sheets. It is demonstrated that observations at the Earth's magnetopause provide evidence of long-term existence of such structures.
Including the relativistic kinetic energy in a spline-augmented plane-wave band calculation
Fehrenbach, G.M.; Schmidt, G.
1997-03-01
The first-order relativistic correction to the kinetic energy of an electron, the mass-velocity term, is not bounded from below. It can, therefore, not be used within a variational framework. To overcome this deficiency we developed a method to include the entire relativistic kinetic energy {radical}(p{sup 2}c{sup 2}+m{sub 0}{sup 2}c{sup 4}){minus}m{sub 0}c{sup 2} in a spline-augmented plane-wave band calculation. The first results for silver are quite promising, especially for d and p states: The analysis of the energies of the core states as well as of the valence band structure suggests that the energies of d bands are reproduced within 1 mRy. However, the combination of the relativistic kinetic energy with the Darwin term leads to energies which are too low for s-like valence states by 10 mRy. Therefore, the s and d valence band complex is spread out and the Fermi level is lowered by the same amount as the s states. We expect to overcome these deficiencies in future investigations by using a alternative form of the relativistic potential correction along the lines proposed by Douglas and Kroll. {copyright} {ital 1997} {ital The American Physical Society}
Laskin, Julia
2015-11-30
In this work, resonant ejection coupled with surface-induced dissociation (SID) in a Fourier transform ion cyclotron resonance mass spectrometer is used to examine fragmentation kinetics of two singly protonated hexapeptides, RYGGFL and KYGGFL, containing the basic arginine residue and less basic lysine residue at the N-terminus. The kinetics of individual reaction channels at different collision energies are probed by applying a short ejection pulse (1 ms) in resonance with the cyclotron frequency of a selected fragment ion and varying the delay time between ion-surface collision and resonant ejection while keeping total reaction delay time constant. Rice-Ramsperger-Kassel-Marcus (RRKM) modeling of the experimental data provides accurate threshold energies and activation entropies of individual reaction channels. Substitution of arginine with less basic lysine has a pronounced effect on the observed fragmentation kinetics of several pathways, including the b2 ion formation, but has little or no effect on formation of the b5+H2O fragment ion. The combination of resonant ejection SID, time- and collision energy-resolved SID, and RRKM modeling of both types of experimental data provides a detailed mechanistic understanding of the primary dissociation pathways of complex gaseous ions.
Turbulent Kinetic Energy in the Oklahoma City Urban Environment
Lundquist, J; Leach, M; Gouveia, F
2004-06-24
A major field experiment, Joint URBAN 2003 (JU2003), was conducted in Oklahoma City in July 2003 to collect meteorological and tracer data sets for evaluating dispersion models in urban areas. The Department of Homeland Security and the Defense Threat Reduction Agency were the primary sponsors of JU2003. Investigators from five Department of Energy national laboratories, several other government agencies, universities, private companies, and international agencies conducted the experiment. Observations to characterize the meteorology in and around the urban area complemented the observation of the dispersion of SF6, an inert tracer gas. Over one hundred threedimensional sonic anemometers were deployed in and around the urban area to monitor wind speed, direction, and turbulence fluxes during releases of SF6. Sonic deployment locations included a profile of eight sonic anemometers mounted on a crane less than 1 km north of the central business district (CBD). Using data from these and other sonic anemometers deployed in the urban area, we can quantify the effect of the urban area on atmospheric turbulence and compare results seen in OKC to those in other urban areas to assess the parameters typically used in parameterizations of urban turbulence.
NASA Astrophysics Data System (ADS)
Pasca, H.; Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.; Kim, Y.
2016-05-01
The mass, charge, isotopic, and kinetic-energy distributions of fission fragments are studied within an improved scission-point statistical model in the reactions 235U+n and 239Pu+n at different energies of the incident neutron. The charge and mass distributions of the electromagnetic- and neutron-induced fission of 214,218Ra, 230,232,238U are also shown. The available experimental data are well reproduced and the energy-dependencies of the observable characteristics of fission are predicted for future experiments.
Kinetics of light-induced ordering and deformation in LC azobenzene-containing materials.
Toshchevikov, Vladimir; Petrova, Tatiana; Saphiannikova, Marina
2017-04-12
Azobenzene-containing smart materials are able to transform the energy of light into directional mechanical stress. We develop a theory of time-dependent light-induced ordering and deformation in azobenzene materials starting from the kinetic equations of photoisomerization. The liquid crystalline (LC) interactions between rod-like trans-isomers are taken into account. Angular selectivity of the photoisomerization known as an "angular hole burning" or the Weigert effect leads to the light-induced ordering and deformation of the azobenzene materials. The time evolution of ordering and deformation is found as a function of intensity of light depending on the opto-mechanical characteristics of the materials, such as probabilities of the optical excitation of trans- and cis-isomers, angular jump during the single isomerization event, viscosity of the materials, strength of the LC interactions in both the isotropic and LC materials, and the angular distribution of chromophores in polymer chains. Established structural-property relationships are in agreement with a number of experiments and can be used for the construction of light-controllable smart materials for practical applications.
Jeon, Jonggu; Cho, Minhaeng
2011-12-07
The vibrational energy transfer from the excited carbonyl stretch mode in N-deuterated N-methylacetamide (NMA-d), both in isolation and in a heavy water cluster, is studied with nonequilibrium molecular dynamics (NEMD) simulations, employing a quantum mechanical/molecular mechanical (QM∕MM) force field at the semiempirical PM3 level. The nonequilibrium ensemble of vibrationally excited NMA-d is prepared by perturbing the positions and velocities of the carbonyl C and O atoms and its NEMD trajectories are obtained with a leap-frog algorithm properly modified for the initial perturbation. In addition to the time-domain analysis of the kinetic and potential energies, a novel method for the spectral analysis of the atomic kinetic energies is developed, in terms of the spectral density of kinetic energy, which provides the time-dependent changes of the frequency-resolved kinetic energies without the complications of normal mode analysis at every MD time step. Due to the QM description of the solute electronic structure, the couplings among the normal modes are captured more realistically than with classical force fields. The energy transfer in the isolated NMA-d is found to proceed first from the carbonyl bond to other modes with time scales of 3 ps or less, and then among the other modes over 3-21 ps. In the solvated NMA-d, most of the excess energy is first transferred to other intramolecular modes within 5 ps, which is subsequently dissipated to solvent with 7-19 ps time scales. The contribution of the direct energy transfer from the carbonyl bond to solvent was only 5% with ~7 ps time scale. Solvent reorganization that leads to destabilization of the electrostatic interactions is found to be crucial in the long time relaxation of the excess energy, while the water intramolecular modes do not contribute significantly. Detailed mode-specific energy transfer pathways are deduced for the isolated and solvated NMA-d and they show that the energy transfer in NMA-d is a
NASA Astrophysics Data System (ADS)
Jeon, Jonggu; Cho, Minhaeng
2011-12-01
The vibrational energy transfer from the excited carbonyl stretch mode in N-deuterated N-methylacetamide (NMA-d), both in isolation and in a heavy water cluster, is studied with nonequilibrium molecular dynamics (NEMD) simulations, employing a quantum mechanical/molecular mechanical (QM/MM) force field at the semiempirical PM3 level. The nonequilibrium ensemble of vibrationally excited NMA-d is prepared by perturbing the positions and velocities of the carbonyl C and O atoms and its NEMD trajectories are obtained with a leap-frog algorithm properly modified for the initial perturbation. In addition to the time-domain analysis of the kinetic and potential energies, a novel method for the spectral analysis of the atomic kinetic energies is developed, in terms of the spectral density of kinetic energy, which provides the time-dependent changes of the frequency-resolved kinetic energies without the complications of normal mode analysis at every MD time step. Due to the QM description of the solute electronic structure, the couplings among the normal modes are captured more realistically than with classical force fields. The energy transfer in the isolated NMA-d is found to proceed first from the carbonyl bond to other modes with time scales of 3 ps or less, and then among the other modes over 3-21 ps. In the solvated NMA-d, most of the excess energy is first transferred to other intramolecular modes within 5 ps, which is subsequently dissipated to solvent with 7-19 ps time scales. The contribution of the direct energy transfer from the carbonyl bond to solvent was only 5% with ˜7 ps time scale. Solvent reorganization that leads to destabilization of the electrostatic interactions is found to be crucial in the long time relaxation of the excess energy, while the water intramolecular modes do not contribute significantly. Detailed mode-specific energy transfer pathways are deduced for the isolated and solvated NMA-d and they show that the energy transfer in NMA-d is a
Low energy electron induced decomposition of phosgene on Ag(111)
NASA Astrophysics Data System (ADS)
Zhou, X.-L.; Coon, S. R.; White, J. M.
1990-01-01
The decomposition, induced by low energy electrons (0-23 eV), of adsorbed phosgene (Cl2CO) on Ag(111) has been studied using temperature programmed desorption (TPD) and x-ray photoelectron spectroscopy (XPS). The electron induced decomposition (EID) products are surface Cl(a) and gas phase CO(g). There is no electron stimulated desorption (ESD) of molecular Cl2CO or atomic Cl. The evolution of CO during EID is readily monitored with a mass spectrometer. The electron kinetic energy threshold for the EID of Cl2CO is near zero eV. The EID cross section is in the range of 10-16-10-15 cm2 and increases with incident electron energy. The EID process is attributed to dissociative electron attachment (DEA) in which incident electrons attach themselves to adsorbed Cl2CO forming Cl2CO- ions as intermediates that dissociate. These results are compared with the photodissociation of Cl2CO on Ag(111).
Measurement of inner radiation belt electrons with kinetic energy above 1 MeV
NASA Astrophysics Data System (ADS)
Selesnick, R. S.
2015-10-01
Data from the Proton-Electron Telescope on the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, taken during 1992-2009, are analyzed for evidence of inner radiation belt electrons with kinetic energy E > 1 MeV. It is found that most of the data from a detector combination with a nominal energy threshold of 1 MeV were, in fact, caused by a chance coincidence response to lower energy electrons or high-energy protons. In particular, there was no detection of inner belt or slot region electrons above 1 MeV following the 2003 Halloween storm injection, though they may have been present. However, by restricting data to a less-stable, low-altitude trapping region, a persistent presence of inner belt electrons in the energy range 1 to 1.6 MeV is demonstrated. Their soft, exponential energy spectra are consistent with extrapolation of lower energy measurements.
Distinctive features of kinetics of plasma at high specific energy deposition
NASA Astrophysics Data System (ADS)
Lepikhin, Nikita; Popov, Nikolay; Starikovskaia, Svetlana
2016-09-01
A nanosecond capillary discharge in pure nitrogen at moderate pressures is used as an experimental tool for plasma kinetics studies at conditions of high specific deposited energy up to 1 eV/molecule. Experimental observations based on electrical (back current shunts, capacitive probe) and spectroscopic measurements (quenching rates; translational, rotational and vibrational temperature measurements) demonstrate that high specific deposited energy, at electric fields of 200-300 Td, can significantly change gas kinetics in the discharge and in the afterglow. The numerical calculations in 1D axially symmetric geometry using experimental data as input parameters show that changes in the plasma kinetics are caused by extremely high excitation degree: up to 10% of molecular nitrogen is electronically excited at present conditions. Distinctive features of kinetics of plasma at high specific energy deposition as well as details of the experimental technique and numerical calculations will be present. The work was partially supported by French National Agency, ANR (PLASMAFLAME Project, 2011 BS09 025 01), AOARD AFOSR, FA2386-13-1-4064 grant (Program Officer Prof. Chiping Li), LabEx Plas@Par and Linked International Laboratory LIA KaPPA (France-Russia).
Wang, Y Y; Grygiel, C; Dufour, C; Sun, J R; Wang, Z G; Zhao, Y T; Xiao, G Q; Cheng, R; Zhou, X M; Ren, J R; Liu, S D; Lei, Y; Sun, Y B; Ritter, R; Gruber, E; Cassimi, A; Monnet, I; Bouffard, S; Aumayr, F; Toulemonde, M
2014-07-18
Modification of surface and bulk properties of solids by irradiation with ion beams is a widely used technique with many applications in material science. In this study, we show that nano-hillocks on CaF2 crystal surfaces can be formed by individual impact of medium energy (3 and 5 MeV) highly charged ions (Xe(22+) to Xe(30+)) as well as swift (kinetic energies between 12 and 58 MeV) heavy xenon ions. For very slow highly charged ions the appearance of hillocks is known to be linked to a threshold in potential energy (Ep) while for swift heavy ions a minimum electronic energy loss per unit length (Se) is necessary. With our results we bridge the gap between these two extreme cases and demonstrate, that with increasing energy deposition via Se the Ep-threshold for hillock production can be lowered substantially. Surprisingly, both mechanisms of energy deposition in the target surface seem to contribute in an additive way, which can be visualized in a phase diagram. We show that the inelastic thermal spike model, originally developed to describe such material modifications for swift heavy ions, can be extended to the case where both kinetic and potential energies are deposited into the surface.
Wang, Y. Y.; Grygiel, C.; Dufour, C.; Sun, J. R.; Wang, Z. G.; Zhao, Y. T.; Xiao, G. Q.; Cheng, R.; Zhou, X. M.; Ren, J. R.; Liu, S. D.; Lei, Y.; Sun, Y. B.; Ritter, R.; Gruber, E.; Cassimi, A.; Monnet, I.; Bouffard, S.; Aumayr, F.; Toulemonde, M.
2014-01-01
Modification of surface and bulk properties of solids by irradiation with ion beams is a widely used technique with many applications in material science. In this study, we show that nano-hillocks on CaF2 crystal surfaces can be formed by individual impact of medium energy (3 and 5 MeV) highly charged ions (Xe22+ to Xe30+) as well as swift (kinetic energies between 12 and 58 MeV) heavy xenon ions. For very slow highly charged ions the appearance of hillocks is known to be linked to a threshold in potential energy (Ep) while for swift heavy ions a minimum electronic energy loss per unit length (Se) is necessary. With our results we bridge the gap between these two extreme cases and demonstrate, that with increasing energy deposition via Se the Ep-threshold for hillock production can be lowered substantially. Surprisingly, both mechanisms of energy deposition in the target surface seem to contribute in an additive way, which can be visualized in a phase diagram. We show that the inelastic thermal spike model, originally developed to describe such material modifications for swift heavy ions, can be extended to the case where both kinetic and potential energies are deposited into the surface. PMID:25034006
NASA Astrophysics Data System (ADS)
Wang, Y. Y.; Grygiel, C.; Dufour, C.; Sun, J. R.; Wang, Z. G.; Zhao, Y. T.; Xiao, G. Q.; Cheng, R.; Zhou, X. M.; Ren, J. R.; Liu, S. D.; Lei, Y.; Sun, Y. B.; Ritter, R.; Gruber, E.; Cassimi, A.; Monnet, I.; Bouffard, S.; Aumayr, F.; Toulemonde, M.
2014-07-01
Modification of surface and bulk properties of solids by irradiation with ion beams is a widely used technique with many applications in material science. In this study, we show that nano-hillocks on CaF2 crystal surfaces can be formed by individual impact of medium energy (3 and 5 MeV) highly charged ions (Xe22+ to Xe30+) as well as swift (kinetic energies between 12 and 58 MeV) heavy xenon ions. For very slow highly charged ions the appearance of hillocks is known to be linked to a threshold in potential energy (Ep) while for swift heavy ions a minimum electronic energy loss per unit length (Se) is necessary. With our results we bridge the gap between these two extreme cases and demonstrate, that with increasing energy deposition via Se the Ep-threshold for hillock production can be lowered substantially. Surprisingly, both mechanisms of energy deposition in the target surface seem to contribute in an additive way, which can be visualized in a phase diagram. We show that the inelastic thermal spike model, originally developed to describe such material modifications for swift heavy ions, can be extended to the case where both kinetic and potential energies are deposited into the surface.
Alterations in glucose kinetics induced by pentobarbital anesthesia
Lang, C.H.; Bagby, G.J.; Spitzer, J.J.
1986-03-05
Pentobarbital is a common anesthetic agent used in animal research that is known to alter sympathetic function and may also affect carbohydrate metabolism. The in vivo effects of iv pentobarbital on glucose homeostasis were studied in chronically catheterized fasted rats. Whole body glucose kinetics, assessed by the constant iv infusion of (6-/sup 3/H)- and (U-/sup 14/C)-glucose, were determined in all rats in the conscious state. Thereafter, glucose metabolism was followed over the next 4 hr in 3 subgroups of rats; conscious, anesthetized with body temperature maintained, and anesthetized with body temperature not maintained. Hypothermia (a 5/sup 0/C decrease) developed spontaneously in anesthetized rats kept at ambient temperature (22/sup 0/C). No differences were seen in MABP and heart rate between conscious and normothermic anesthetized rats; however, hypothermic anesthetized rats showed a decrease in MABP (20%) and heart rate (35%). Likewise, plasma glucose and lactate concentrations, the rate of glucose appearance (Ra), recycling and metabolic clearance (MCR) did not differ between conscious and normothermic anesthetized animals. In contrast, hypothermic anesthetized rats showed a 50% reduction in plasma lactate, a 40% drop in glucose Ra, and a 30-40% decrease in glucose recycling and MCR. Thus, pentobarbital does not appear to alter in vivo glucose kinetics, compared to unanesthetized controls, provided that body temperature is maintained.
Alterations in glucose kinetics induced by pentobarbital anesthesia
Lang, C.H.; Bagby, G.J.; Hargrove, D.M.; Hyde, P.M.; Spitzer, J.J. )
1987-12-01
Because pentobarbital is often used in investigations related to carbohydrate metabolism, the in vivo effect of this drug on glucose homeostasis was studied. Glucose kinetics assessed by the constant intravenous infusion of (6-{sup 3}H)- and (U-{sup 14}C)glucose, were determined in three groups of catheterized fasted rats: conscious, anesthetized and body temperature maintained, and anesthetized but body temperature not maintained. After induction of anesthesia, marked hypothermia developed in rats not provided with external heat. Anesthetized rats that developed hypothermia showed a decrease in mean arterial blood pressure (25%) and heart rate (40%). Likewise, the plasma lactate concentration and the rates of glucose appearance, recycling, and metabolic clearance were reduced by 30-50% in the hypothermic anesthetized rats. Changes in whole-body carbohydrate metabolism were prevented when body temperature was maintained. Because plasma pentobarbital levels were similar between the euthermic and hypothermic rats during the first 2 h of the experiment, the rapid reduction in glucose metabolism in this latter group appears related to the decrease in body temperature. The continuous infusion of epinephrine produced alterations in glucose kinetics that were not different between conscious animals and anesthetized rats with body temperature maintained. Thus pentobarbital-anesthetized rats became hypothermic when kept at room temperature and exhibited marked decreases in glucose metabolism. Such changes were absent when body temperature was maintained during anesthesia.
Buoyant production and consumption of turbulence kinetic energy in cloud-topped mixed layers
NASA Technical Reports Server (NTRS)
Randall, D. A.
1984-01-01
It is pointed out that studies of the entraining planetary boundary layer (PBL) have generally emphasized the role of buoyancy fluxes in driving entrainment. The buoyancy flux is proportional to the rate of conversion of the potential energy of the mean flow into the kinetic energy of the turbulence. It is not unusual for conversion to proceed in both directions simultaneously. This occurs, for instance, in both clear and cloudy convective mixed layers which are capped by inversions. A partitioning of the net conversion into positive parts, generating turbulence kinetic energy (TKE), and negative parts (TKE-consuming), would make it possible to include the positive part in the gross production rate, and closure would be achieved. Three different approaches to partitioning have been proposed. The present investigation is concerned with a comparison of the three partitioning theories. Particular attention is given to the cloud-topped mixed layer because in this case the differences between two partitioning approaches are most apparent.
Kinetic Energy of Hydrocarbons as a Function of Electron Density and Convolutional Neural Networks.
Yao, Kun; Parkhill, John
2016-03-08
We demonstrate a convolutional neural network trained to reproduce the Kohn-Sham kinetic energy of hydrocarbons from an input electron density. The output of the network is used as a nonlocal correction to conventional local and semilocal kinetic functionals. We show that this approximation qualitatively reproduces Kohn-Sham potential energy surfaces when used with conventional exchange correlation functionals. The density which minimizes the total energy given by the functional is examined in detail. We identify several avenues to improve on this exploratory work, by reducing numerical noise and changing the structure of our functional. Finally we examine the features in the density learned by the neural network to anticipate the prospects of generalizing these models.
Buoyant production and consumption of turbulence kinetic energy in cloud-topped mixed layers
NASA Technical Reports Server (NTRS)
Randall, D. A.
1984-01-01
It is pointed out that studies of the entraining planetary boundary layer (PBL) have generally emphasized the role of buoyancy fluxes in driving entrainment. The buoyancy flux is proportional to the rate of conversion of the potential energy of the mean flow into the kinetic energy of the turbulence. It is not unusual for conversion to proceed in both directions simultaneously. This occurs, for instance, in both clear and cloudy convective mixed layers which are capped by inversions. A partitioning of the net conversion into positive parts, generating turbulence kinetic energy (TKE), and negative parts (TKE-consuming), would make it possible to include the positive part in the gross production rate, and closure would be achieved. Three different approaches to partitioning have been proposed. The present investigation is concerned with a comparison of the three partitioning theories. Particular attention is given to the cloud-topped mixed layer because in this case the differences between two partitioning approaches are most apparent.
Robiche, J.; Rax, J.-M.; Bonnaud, G.; Gremillet, L.
2010-03-15
The collisional dynamics of a relativistic electron jet in a magnetized plasma are investigated within the framework of kinetic theory. The relativistic Fokker-Planck equation describing slowing down, pitch angle scattering, and cyclotron rotation is derived and solved. Based on the solution of this Fokker-Planck equation, an analytical formula for the root mean square spot size transverse to the magnetic field is derived and this result predicts a reduction in radial transport. Some comparisons with particle-in-cell simulation are made and confirm striking agreement between the theory and the simulation. For fast electron with 1 MeV typical kinetic energy interacting with a solid density hydrogen plasma, the energy deposition density in the transverse direction increases by a factor 2 for magnetic field of the order of 1 T. Along the magnetic field, the energy deposition profile is unaltered compared with the field-free case.
Rock Cutting Depth Model Based on Kinetic Energy of Abrasive Waterjet
NASA Astrophysics Data System (ADS)
Oh, Tae-Min; Cho, Gye-Chun
2016-03-01
Abrasive waterjets are widely used in the fields of civil and mechanical engineering for cutting a great variety of hard materials including rocks, metals, and other materials. Cutting depth is an important index to estimate operating time and cost, but it is very difficult to predict because there are a number of influential variables (e.g., energy, geometry, material, and nozzle system parameters). In this study, the cutting depth is correlated to the maximum kinetic energy expressed in terms of energy (i.e., water pressure, water flow rate, abrasive feed rate, and traverse speed), geometry (i.e., standoff distance), material (i.e., α and β), and nozzle system parameters (i.e., nozzle size, shape, and jet diffusion level). The maximum kinetic energy cutting depth model is verified with experimental test data that are obtained using one type of hard granite specimen for various parameters. The results show a unique curve for a specific rock type in a power function between cutting depth and maximum kinetic energy. The cutting depth model developed here can be very useful for estimating the process time when cutting rock using an abrasive waterjet.
Near-surface mean circulation and kinetic energy in the central North Atlantic from drifter data
NASA Astrophysics Data System (ADS)
Brügge, Bernd
1995-10-01
An analysis of a large drifting buoy data set is presented. The objective is to obtain a self-contained description of the properties of the near-surface circulation (drogue depth 100 m) in the central North Atlantic Ocean, independent of hydrographic data. A necessary preanalysis step was the removal of all data from undrogued buoys from the data set. The physical parameters of the circulation were deduced by averaging the remaining data in 2°×3° boxes. The minimum amount of data which is necessary to get statistically stable results was determined by an empirical quality criterion. All important mean currents in the investigation area are reproduced by the near-surface mean velocity field. A separation of the mean velocity field into a nondivergent and an irrational part shows that the flow field is almost nondivergent. The distribution of eddy kinetic energy is concentrated along the mean currents and provides the largest part of the total kinetic energy, but there are regional variations. Energy from inertial movements dominates the high-frequency part of the kinetic energy. Its distribution is very patchy. The analysis of the Reynolds stress terms shows an energy transfer from the eddy field to the mean circulation in the vicinity of the North Atlantic Current.
Kinetic treatment of alpha-particle loss and energy deposition in ELMO Bumpy Torus
Fenstermacher, M.E.; Uckan, N.A.
1982-12-01
A formalism has been developed in terms of a drift kinetic equation with a Fokker-Planck collision operator to calculate alpha particle loss and energy deposition rate coefficients for one position in space and for steady-state operating conditions. A bounce-averaged drift kinetic equation for an ELMO Bumpy Torus (EBT) is expressed in invariant variables E = v/sup 2//2 and lambda = v/sub perpendicular//sup 2/B/sub MID//v/sup 2/B(l) and is used with energy scattering and pitch angle scattering terms in the collision operator. The alpha particle distribution function is expanded in terms of energy coefficients and pitch angle eigenfunctions. For the case of a square well magnetic field shape, the pitch angle eigenfunctions are the Legendre polynominals. With an expression for the distribution function the particle loss and energy deposition rates are calculated by taking the zeroth and first-order energy moments, respectively, of the kinetic equation.
Osváth, Szabolcs; Herényi, Levente; Závodszky, Péter; Fidy, Judit; Köhler, Gottfried
2006-08-25
One of the most intriguing predictions of energy landscape models is the existence of non-exponential protein folding kinetics caused by hierarchical structures in the landscapes. Here we provide the strongest evidence so far of such hierarchy and determine the time constants and weights of the kinetic components of the suggested hierarchic energy landscape. To our knowledge, the idea of hierarchical folding energy barriers has never been tested over such a broad timescale. Refolding of yeast phosphoglycerate kinase was initiated from the guanidine-unfolded state by stopped-flow or manual mixing and monitored by tryptophan fluorescence from 1 ms to 15 min. The strategy to build a model that describes folding of yeast phosphoglycerate kinase was to start from the simplest paradigm and modify it stepwise to the necessary minimal extent after repeated comparisons with the experiments. We made no a priori assumptions about the folding landscape. The result was a hierarchic finite level landscape model that quantitatively describes the refolding of yeast phosphoglycerate kinase from 1 ms to 15 min. The early steps of the folding process happen in the upper region of the landscape, where the surface has a hierarchic structure. This leads to stretched kinetics in the early phase of the folding. The lower region of the energy landscape is dominated by a trap that reflects the accumulation of molten globule intermediate state. From this intermediate, the protein can reach the global energy minimum corresponding to the native state through a cross-barrier folding step.
Electron scattering as a tool to study zero-point kinetic energies of atoms in molecules
NASA Astrophysics Data System (ADS)
Moreh, R.; Finkelstein, Y.; Vos, M.
2015-07-01
High resolution electron compton scattering (ECS) is being used to study the atomic momentum distributions and hence the zero-point kinetic energies (ZPKE) of the scattering atoms. Such studies have shown that the scattering is from a single atom of the scattering sample. For an electron beam with a well defined incident energy, the scattered electron energy at any angle from each atomic species is Doppler broadened. The broadening reflects the atomic momentum distribution contributed by both the internal and external motions of the molecular system. By measuring the Doppler broadening of the scattered electron lines it was possible to determine the kinetic energy of the scattering atom including that of its zero-point motion. Thus, the atomic kinetic energies in gases such as H2, D2, HD, CH4 and in H2O, D2O and NH3 were measured and compared with those calculated semi-empirically using the measured optical infra red (IR) and Raman frequencies of the internal vibrations of the molecules. In general, good agreement between the measured and calculated values was found. Electron scattering was also used to study the ratio of e-scattering intensities from the H- and O-atoms in water (H2O), where some anomalies were reported to exist.
Kinetic energy of throughfall in a highly diverse forest ecosystem in the humid subtropics
NASA Astrophysics Data System (ADS)
Geißler, Christian; Kühn, Peter; Scholten, Thomas
2010-05-01
After decades of research it is generally accepted that vegetation is a key factor in controlling soil erosion. Therefore, in ecosystems where erosion is a serious problem, afforestation is a common measure against erosion. Most of the studies in the last decades focused on agricultural systems and less attention was paid to natural systems. To understand the mechanisms preventing soil erosion in natural systems the processes have to be studied in detail and gradually. The first step and central research question is on how the canopies of the tree layer alter the properties of rainfall and generate throughfall. Kinetic energy is a widely used parameter to estimate the erosion potential of open field rainfall and throughfall. In the past, numerous studies have shown that vegetation of a certain height enhances the kinetic energy under the canopy (Chapman 1948, Mosley 1982, Vis 1986, Hall & Calder 1993, Nanko et al. 2006, Nanko et al. 2008) in relation to open field rainfall. This is mainly due to a shift in the drop size distribution to less but larger drops possessing a higher amount of kinetic energy. In vital forest ecosystems lower vegetation (shrubs, herbs) as well as a continuous litter layer protects the forest soil from the impact of large drops. The influence of biodiversity, specific forest stands or single species in this process system is still in discussion. In the present study calibrated splash cups (after Ellison 1947, Geißler et al. under review) have been used to detect differences in kinetic energy on the scale of specific species and on the scale of forest stands of contrasting age and biodiversity in a natural forest ecosystem. The splash cups have been calibrated experimentally using a laser disdrometer. The results show that the kinetic energy of throughfall produced by the tree layer increases with the age of the specific forest stand. The average throughfall kinetic energy (J m-2) is about 2.6 times higher in forests than under open field
Statistical model of a flexible inextensible polymer chain: The effect of kinetic energy.
Pergamenshchik, V M; Vozniak, A B
2017-01-01
Because of the holonomic constraints, the kinetic energy contribution in the partition function of an inextensible polymer chain is difficult to find, and it has been systematically ignored. We present the first thermodynamic calculation incorporating the kinetic energy of an inextensible polymer chain with the bending energy. To explore the effect of the translation-rotation degrees of freedom, we propose and solve a statistical model of a fully flexible chain of N+1 linked beads which, in the limit of smooth bending, is equivalent to the well-known wormlike chain model. The partition function with the kinetic and bending energies and correlations between orientations of any pair of links and velocities of any pair of beads are found. This solution is precise in the limits of small and large rigidity-to-temperature ratio b/T. The last exact solution is essential as even very "harmless" approximation results in loss of the important effects when the chain is very rigid. For very high b/T, the orientations of different links become fully correlated. Nevertheless, the chain does not go over into a hard rod even in the limit b/T→∞: While the velocity correlation length diverges, the correlations themselves remain weak and tend to the value ∝T/(N+1). The N dependence of the partition function is essentially determined by the kinetic energy contribution. We demonstrate that to obtain the correct energy and entropy in a constrained system, the T derivative of the partition function has to be applied before integration over the constraint-setting variable.
Statistical model of a flexible inextensible polymer chain: The effect of kinetic energy
NASA Astrophysics Data System (ADS)
Pergamenshchik, V. M.; Vozniak, A. B.
2017-01-01
Because of the holonomic constraints, the kinetic energy contribution in the partition function of an inextensible polymer chain is difficult to find, and it has been systematically ignored. We present the first thermodynamic calculation incorporating the kinetic energy of an inextensible polymer chain with the bending energy. To explore the effect of the translation-rotation degrees of freedom, we propose and solve a statistical model of a fully flexible chain of N +1 linked beads which, in the limit of smooth bending, is equivalent to the well-known wormlike chain model. The partition function with the kinetic and bending energies and correlations between orientations of any pair of links and velocities of any pair of beads are found. This solution is precise in the limits of small and large rigidity-to-temperature ratio b /T . The last exact solution is essential as even very "harmless" approximation results in loss of the important effects when the chain is very rigid. For very high b /T , the orientations of different links become fully correlated. Nevertheless, the chain does not go over into a hard rod even in the limit b /T →∞ : While the velocity correlation length diverges, the correlations themselves remain weak and tend to the value ∝T /(N +1 ). The N dependence of the partition function is essentially determined by the kinetic energy contribution. We demonstrate that to obtain the correct energy and entropy in a constrained system, the T derivative of the partition function has to be applied before integration over the constraint-setting variable.
Kinetic energy budget during strong jet stream activity over the eastern United States
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Scoggins, J. R.
1980-01-01
Kinetic energy budgets are computed during a cold air outbreak in association with strong jet stream activity over the eastern United States. The period is characterized by large generation of kinetic energy due to cross-contour flow. Horizontal export and dissipation of energy to subgrid scales of motion constitute the important energy sinks. Rawinsonde data at 3 and 6 h intervals during a 36 h period are used in the analysis and reveal that energy fluctuations on a time scale of less than 12 h are generally small even though the overall energy balance does change considerably during the period in conjunction with an upper level trough which moves through the region. An error analysis of the energy budget terms suggests that this major change in the budget is not due to random errors in the input data but is caused by the changing synoptic situation. The study illustrates the need to consider the time and space scales of associated weather phenomena in interpreting energy budgets obtained through use of higher frequency data.
A kinetic analysis of strand breaks on large DNA induced by cigarette smoke extract
NASA Astrophysics Data System (ADS)
Kurita, Hirofumi; Takata, Tatsuya; Yasuda, Hachiro; Takashima, Kazunori; Mizuno, Akira
2010-06-01
We report a kinetic analysis of strand breakages on large DNA molecules induced by cigarette smoke extract (CSE), an extract of soluble cigarette smoke components. Previously, this DNA damage was analyzed by agarose gel electrophoresis, whereas we used fluorescence to kinetically analyze damage to individual DNA molecules. CSE caused a marked change in length of DNA molecules. The rate of CSE-induced double-strand breakage on large random-coiled DNA molecules was determined using a simple theoretical model, allowing the facile estimation of the rate of double-strand breaks on large DNA molecules.
Proton kinetic effects and turbulent energy cascade rate in the solar wind.
Osman, K T; Matthaeus, W H; Kiyani, K H; Hnat, B; Chapman, S C
2013-11-15
The first observed connection between kinetic instabilities driven by proton temperature anisotropy and estimated energy cascade rates in the turbulent solar wind is reported using measurements from the Wind spacecraft at 1 AU. We find enhanced cascade rates are concentrated along the boundaries of the (β∥, T⊥/T∥) plane, which includes regions theoretically unstable to the mirror and firehose instabilities. A strong correlation is observed between the estimated cascade rate and kinetic effects such as temperature anisotropy and plasma heating, resulting in protons 5-6 times hotter and 70%-90% more anisotropic than under typical isotropic plasma conditions. These results offer new insights into kinetic processes in a turbulent regime.
Proton Kinetic Effects and Turbulent Energy Cascade Rate in the Solar Wind
NASA Astrophysics Data System (ADS)
Osman, K. T.; Matthaeus, W. H.; Kiyani, K. H.; Hnat, B.; Chapman, S. C.
2013-11-01
The first observed connection between kinetic instabilities driven by proton temperature anisotropy and estimated energy cascade rates in the turbulent solar wind is reported using measurements from the Wind spacecraft at 1 AU. We find enhanced cascade rates are concentrated along the boundaries of the (β∥, T⊥/T∥) plane, which includes regions theoretically unstable to the mirror and firehose instabilities. A strong correlation is observed between the estimated cascade rate and kinetic effects such as temperature anisotropy and plasma heating, resulting in protons 5-6 times hotter and 70%-90% more anisotropic than under typical isotropic plasma conditions. These results offer new insights into kinetic processes in a turbulent regime.
Proton Kinetic Effects and Turbulent Energy Cascade Rate in the Solar Wind
NASA Astrophysics Data System (ADS)
Osman, K.; Matthaeus, W. H.; Kiyani, K. H.; Hnat, B.; Chapman, S. C.
2013-12-01
The first observed connection between kinetic instabilities driven by proton temperature anisotropy and estimated energy cascade rates in the turbulent solar wind is reported using measurements from the Wind spacecraft at 1 AU. We find enhanced cascade rates are concentrated along the boundaries of the (β‖,T⊥/T‖)-plane, which includes regions theoretically unstable to the mirror and firehose instabilities. A strong correlation is observed between the estimated cascade rates and kinetic effects such as temperature anisotropy and plasma heating, resulting in protons 5-6 times hotter and 70-90% more anisotropic than under typical isotropic plasma conditions. These results offer new insights into kinetic processes in a turbulent regime.
Effects of crystal-melt interfacial energy anisotropy on dendritic morphology and growth kinetics
NASA Technical Reports Server (NTRS)
Glicksman, M. E.; Singh, N. B.
1989-01-01
Morphological and kinetic studies of succinonitrile, a BCC crystal with a low (0.5 percent) anisotropy and pivalic acid, and FCC crystal with relatively large (5 percent) anisotropy in solid-liquid interfacial energy, show clearly that anisotropy in the solid-liquid interfacial energy does not affect the tip radius-velocity relationship, but has a profound influence on the tip region and the rate of amplification of branching waves. Anisotropy of the solid-liquid interfacial energy may be one of the key factors by which the microstructural characteristics of cast structures reflect individual material behavior, especially crystal symmetry.
NASA Astrophysics Data System (ADS)
Blackman, Karin; Perret, Laurent; Calmet, Isabelle; Rivet, Cédric
2017-08-01
In the present work, a boundary layer developing over a rough-wall consisting of staggered cubes with a plan area packing density λp = 25% is studied within the wind tunnel using Particle Image Velocimetry (PIV) to investigate the Turbulent Kinetic Energy (TKE) budget. To access the full TKE budget, an estimation of the dissipation (ɛ) using both the transport equation of the resolved-scale kinetic energy and Large-Eddy (LE) PIV models based on the use of a subgrid-scale model following the methodology used in large-eddy simulations is employed. A low-pass filter, larger than the Taylor microscale, is applied to the data prior to the computation of the velocity gradients ensuring a clear cutoff in the inertial range where the models are valid. The presence of the cube roughness elements has a significant influence on the TKE budget due to the region of strong shear that develops over the cubes. The shear layer is shown to produce and dissipate energy, as well as transport energy through advection, turbulent transport, and pressure transport. The recirculation region that forms through the interaction of the shear layer and the canopy layer, which is the region below the height of the cube roughness, creates rapid longitudinal evolution of the mean flow thereby inducing weak production. Finally, through stochastic estimation of the conditional average, it is shown that localized regions of backscatter (energy transfer from unresolved to resolved scales) and forward scatter (energy transfer from resolved to unresolved scales) occur as a result of coherent vortical structures.
Induced innovation, energy prices, and the environment
NASA Astrophysics Data System (ADS)
Popp, David Clifford
The process of developing new technologies is a central question for economic theory as well as for public policy in many areas. For example, the development of cleaner, more efficient energy technologies will play an important role in reducing the threat of global warming. To study how technology evolves over time, this dissertation uses patent data on energy innovations from 1970 to 1991 to examine the impact of energy prices on energy-efficient innovations. Before this can be done, however, information on supply-side factors which influence innovation is also needed. In the case of innovation, supply-side factors are the usefulness of the existing base of scientific knowledge. Patent citations are used for this purpose. Subsequent citations to patents granted each year since 1970 are used to show that the returns to research and development (R&D) fall over time for most of the technologies studied. These estimates are then combined with data on demand-side factors, such as energy prices, to estimate a model of induced innovation in energy technologies. Both energy prices and the supply of knowledge are found to have strongly significant positive effects on innovation. Next, the Yale Technology Concordance (YTC), which maps patents to the industries in which they are used, is employed to construct a stock of energy-related knowledge for 14 energy intensive industries. The effect of changes in this stock on energy consumption in these industries is estimated. On average, the present value of energy savings resulting from a new patent is eight million dollars, with the maximum savings coming about five years after the initial patent application. Finally, the results of each regression are combined to simulate the impact of a ten percent energy tax. Initially, simple factor substitution due to the price change has the largest effect. However, because of the cumulative nature of R&D, induced innovation has a much larger effect than factor substitution in the long run
Effect of Self-generated Radial Electric Field on Internal Collapse induced by m=1 Kinetic Kink Mode
NASA Astrophysics Data System (ADS)
Matsumoto, Taro; Tokuda, Shinji; Kishimoto, Yasuaki; Takizuka, Tomonori; Naitou, Hiroshi
1998-11-01
Effect of Self-generated Radial Electric Field on Internal Collapse induced by m=1 Kinetic Kink Mode Matsumoto Taro, Tokuda Shinji, Kishimoto Yasuaki, Takizuka Tomonori Naka Fusion Research Establishment, Japan Atomic Energy Research Institute, Japan and Naitou Hiroshi Department of Electrical and Electronic Engineering, Yamaguchi University, Japan The density gradient effect is taken into account in the gyro-kinetic nonlinear simulation of the kinetic m=1 internal kink mode in a cylindrical plasma. Even when the density gradient is not so large enough to change the process of the full reconnection, the process of the post-reconnection phase is changed considerably due to the self-generated radial electric field, i.e. m/n = 0/0 mode induced by the nonlinear interaction. The radial electric field grows to the same level as the 1/1 mode, and drives a ExB plasma rotation in the ion diamagnetic direction. The density and current distribution, and therefore q-min value after the full reconnection, are found to be significantly affected by the rotation.
Levin, J D; Ting-Beall, H P; Hochmuth, R M
2001-01-01
Many human diseases are mediated through the immune system. In chronic inflammatory disorders, the processes ordinarily involved in tissue healing become destructive. Endothelial cells normally recruit leukocytes to inflamed tissue using cytokine-induced adhesion receptors on the surfaces of interacting cells. Leukocyte capture depends on specialized characteristics of these receptors, particularly the binding kinetics. This study is designed to clarify the relationship between cytokine-induced changes in cell properties and binding kinetics. Here, we measure the kinetics of expression and monoclonal antibody binding for E-selectin in interleukin-1alpha-stimulated microvascular endothelium in vitro and incorporate the data into kinetic models. Quantitative flow cytometry is used to determine molecular density (expression), and micropipette assays are used to find the probability of adhesion (function). Within five hours of interleukin-1alpha stimulation, E-selectin density increases from 0 to 742 sites/microm(2), and antibody-E-selectin adhesion probability increases from a baseline of 6.3% to 64%. A kinetic model is applied to find an apparent association rate constant, k(f), of 3.7 x 10(-14) cm(2)/sec for antibody-E-selectin binding. Although the model successfully predicts experimental results, the rate constant is undervalued for a diffusion-limited process, suggesting that functional adhesion may be modified through cytokine-induced changes in microtopology and receptor localization. PMID:11159434
Adaptive coarse graining method for energy transfer and dissociation kinetics of polyatomic species.
Sahai, A; Lopez, B; Johnston, C O; Panesi, M
2017-08-07
A novel reduced-order method is presented for modeling reacting flows characterized by strong non-equilibrium of the internal energy level distribution of chemical species in the gas. The approach seeks for a reduced-order representation of the distribution function by grouping individual energy states into macroscopic bins, and then reconstructing state population using the maximum entropy principle. This work introduces an adaptive grouping methodology to identify and lump together groups of states that are likely to equilibrate faster with respect to each other. To this aim, two algorithms have been considered: the modified island algorithm and the spectral clustering method. Both methods require a measure of dissimilarity between internal energy states. This is achieved by defining "metrics" based on the strength of the elementary rate coefficients included in the state-specific kinetic mechanism. Penalty terms are used to avoid grouping together states characterized by distinctively different energies. The two methods are used to investigate excitation and dissociation of N2 (Σg+1) molecules due to interaction with N(Su4) atoms in an ideal chemical reactor. The results are compared with a direct numerical simulation of the state-specific kinetics obtained by solving the master equations for the complete set of energy levels. It is found that adaptive grouping techniques outperform the more conventional uniform energy grouping algorithm by providing a more accurate description of the distribution function, mole fraction and energy profiles during non-equilibrium relaxation.
Adaptive coarse graining method for energy transfer and dissociation kinetics of polyatomic species
NASA Astrophysics Data System (ADS)
Sahai, A.; Lopez, B.; Johnston, C. O.; Panesi, M.
2017-08-01
A novel reduced-order method is presented for modeling reacting flows characterized by strong non-equilibrium of the internal energy level distribution of chemical species in the gas. The approach seeks for a reduced-order representation of the distribution function by grouping individual energy states into macroscopic bins, and then reconstructing state population using the maximum entropy principle. This work introduces an adaptive grouping methodology to identify and lump together groups of states that are likely to equilibrate faster with respect to each other. To this aim, two algorithms have been considered: the modified island algorithm and the spectral clustering method. Both methods require a measure of dissimilarity between internal energy states. This is achieved by defining "metrics" based on the strength of the elementary rate coefficients included in the state-specific kinetic mechanism. Penalty terms are used to avoid grouping together states characterized by distinctively different energies. The two methods are used to investigate excitation and dissociation of N2 (g+1Σ) molecules due to interaction with N (S4u ) atoms in an ideal chemical reactor. The results are compared with a direct numerical simulation of the state-specific kinetics obtained by solving the master equations for the complete set of energy levels. It is found that adaptive grouping techniques outperform the more conventional uniform energy grouping algorithm by providing a more accurate description of the distribution function, mole fraction and energy profiles during non-equilibrium relaxation.
Scale-to-scale energy transfer in mixing flow induced by the Richtmyer-Meshkov instability
NASA Astrophysics Data System (ADS)
Liu, Han; Xiao, Zuoli
2016-05-01
The Richtmyer-Meshkov instability (RMI) mixing flow induced by a planar shock wave of Mach 1.6 is investigated using direct numerical simulation method. Interfacial perturbations of different scales between air and sulfur hexafluoride are introduced to study the effect of the initial conditions. Focus is placed on the analysis of the scale-to-scale transfer of kinetic energy in both Fourier and physical spaces. The kinetic energy injected from the perturbation scales is transferred to both larger and smaller scales in an average sense within the inner mixing zone (IMZ) at early times and is mainly passed down into smaller scales at the late stage. The physical-space energy flux due to the subgrid-scale (SGS) stress is studied using a filtering approach in order to shed light on the physical origin of the scale-to-scale kinetic energy transfer. It is found that the pointwise SGS energy flux is highly correlated with the local spike and bubble structures in the IMZ. Moreover, it turns out that the mean SGS energy flux is mainly ascribed to the component in the direction of shock wave propagation. An analysis using the method of conditional averaging manifests that the generation of local SGS energy flux is associated with the property of the surrounding flow induced by quadrupolar or dipolar vortex structures.
Scale-to-scale energy transfer in mixing flow induced by the Richtmyer-Meshkov instability.
Liu, Han; Xiao, Zuoli
2016-05-01
The Richtmyer-Meshkov instability (RMI) mixing flow induced by a planar shock wave of Mach 1.6 is investigated using direct numerical simulation method. Interfacial perturbations of different scales between air and sulfur hexafluoride are introduced to study the effect of the initial conditions. Focus is placed on the analysis of the scale-to-scale transfer of kinetic energy in both Fourier and physical spaces. The kinetic energy injected from the perturbation scales is transferred to both larger and smaller scales in an average sense within the inner mixing zone (IMZ) at early times and is mainly passed down into smaller scales at the late stage. The physical-space energy flux due to the subgrid-scale (SGS) stress is studied using a filtering approach in order to shed light on the physical origin of the scale-to-scale kinetic energy transfer. It is found that the pointwise SGS energy flux is highly correlated with the local spike and bubble structures in the IMZ. Moreover, it turns out that the mean SGS energy flux is mainly ascribed to the component in the direction of shock wave propagation. An analysis using the method of conditional averaging manifests that the generation of local SGS energy flux is associated with the property of the surrounding flow induced by quadrupolar or dipolar vortex structures.
Atomic kinetic research of ordered quantum dot growth induced by dislocation on the substrate
NASA Astrophysics Data System (ADS)
Zhao, Chang; Zhao, M.; Wang, Y.; Lv, A. J.; Xing, G. J.; Ma, Y. C.
2014-01-01
In this study, the modified effects of stress originating from the dislocation on the substrate to the semiconductor quantum dot growth are investigated by performing an event-based continuous kinetic Monte Carlo simulation, in which the contribution of the dangling bond of the atom is considered. The research results indicate that the change of binding energy initiated by the stress between the deposit atom and the substrate's atoms may significantly influence the atoms' kinetic behaviors, and on the pattern surface the atoms' kinetic effects are very sensitive to the initial condition of the substrate. In addition, the dependence of the atomic kinetics on the growth flux and temperature are also studied. The simulation results are in good qualitative agreement with those of our experiment.
Strobusch, D; Scheurer, Ch
2011-09-28
A new hierarchical expansion of the kinetic energy operator in curvilinear coordinates is presented and modified vibrational self-consistent field (VSCF) equations are derived including all kinematic effects within the mean field approximation. The new concept for the kinetic energy operator is based on many-body expansions for all G matrix elements and its determinant. As a test application VSCF computations were performed on the H(2)O(2) molecule using an analytic potential (PCPSDE) and different hierarchical approximations for the kinetic energy operator. The results indicate that coordinate-dependent reduced masses account for the largest part of the kinetic energy. Neither kinematic couplings nor derivatives of the G matrix nor its determinant had significant effects on the VSCF energies. Only the zero-point value of the pseudopotential yields an offset to absolute energies which, however, is irrelevant for spectroscopic problems.
Chattoraj, Sayantan; Bhugra, Chandan; Li, Zheng Jane; Sun, Changquan Calvin
2014-12-01
The nonisothermal crystallization kinetics of amorphous materials is routinely analyzed by statistically fitting the crystallization data to kinetic models. In this work, we systematically evaluate how the model-dependent crystallization kinetics is impacted by variations in the heating rate and the selection of the kinetic model, two key factors that can lead to significant differences in the crystallization activation energy (Ea ) of an amorphous material. Using amorphous felodipine, we show that the Ea decreases with increase in the heating rate, irrespective of the kinetic model evaluated in this work. The model that best describes the crystallization phenomenon cannot be identified readily through the statistical fitting approach because several kinetic models yield comparable R(2) . Here, we propose an alternate paired model-fitting model-free (PMFMF) approach for identifying the most suitable kinetic model, where Ea obtained from model-dependent kinetics is compared with those obtained from model-free kinetics. The most suitable kinetic model is identified as the one that yields Ea values comparable with the model-free kinetics. Through this PMFMF approach, nucleation and growth is identified as the main mechanism that controls the crystallization kinetics of felodipine. Using this PMFMF approach, we further demonstrate that crystallization mechanism from amorphous phase varies with heating rate. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.
Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave
NASA Astrophysics Data System (ADS)
Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; Boardsen, Scott A.; Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.; Saito, Yoshifumi; Paterson, William R.; Fuselier, Stephen A.; Ergun, Robert E.; Strangeway, Robert J.; Russell, Christopher T.; Giles, Barbara L.; Pollock, Craig J.; Torbert, Roy B.; Burch, James L.
2017-03-01
Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.
Budget of Turbulent Kinetic Energy in a Shock Wave Boundary-Layer Interaction
NASA Technical Reports Server (NTRS)
Vyas, Manan A.; Waindim, Mbu; Gaitonde, Datta V.
2016-01-01
Implicit large-eddy simulation (ILES) of a shock wave/boundary-layer interaction (SBLI) was performed. Quantities present in the exact equation of the turbulent kinetic energy transport were accumulated and used to calculate terms like production, dissipation, molecular diffusion, and turbulent transport. The present results for a turbulent boundary layer were validated by comparison with direct numerical simulation data. It was found that a longer development domain was necessary for the boundary layer to reach an equilibrium state and a finer mesh resolution would improve the predictions. In spite of these findings, trends of the present budget match closely with that of the direct numerical simulation. Budgets for the SBLI region are presented at key axial stations. These budgets showed interesting dynamics as the incoming boundary layer transforms and the terms of the turbulent kinetic energy budget change behavior within the interaction region.
Traumatic thrombosis of internal carotid artery sustained by transfer of kinetic energy.
Kalcioglu, Mahmut Tayyar; Celbis, Osman; Mizrak, Bulent; Firat, Yezdan; Selimoglu, Erol
2012-06-01
A 31-year-old male patient with a fatal thrombosis of the internal carotid artery caused by gun shot injury was presented in this case report. The patient was referred to the hospital with a diffuse edema on his left cheek. On otolaryngologic examination, there was a bullet entrance hole at the left mandibular corpus. No exit hole could be found. The finding from his axial computed tomography of neck and paranasal sinuses was normal. On neurological examination, a dense right hemiparesis was observed. In his cerebral angiogram, left common carotid artery was totally obliterated. Diffuse ischemia was observed in the left cerebral hemisphere. Despite intensive interventions, the patient died 4 days after the accident. In the autopsy, a large thrombosis was obtained in the left common carotid artery. This case emphasizes a fatal kinetic energy effect in vascular structures. It is stressed that a gun shot injury could be fatal with its indirect kinetic energy effects at subacute phase.
The genetic code and its optimization for kinetic energy conservation in polypeptide chains.
Guilloux, Antonin; Jestin, Jean-Luc
2012-08-01
Why is the genetic code the way it is? Concepts from fields as diverse as molecular evolution, classical chemistry, biochemistry and metabolism have been used to define selection pressures most likely to be involved in the shaping of the genetic code. Here minimization of kinetic energy disturbances during protein evolution by mutation allows an optimization of the genetic code to be highlighted. The quadratic forms corresponding to the kinetic energy term are considered over the field of rational numbers. Arguments are given to support the introduction of notions from basic number theory within this context. The observations found to be consistent with this minimization are statistically significant. The genetic code may well have been optimized according to energetic criteria so as to improve folding and dynamic properties of polypeptide chains. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.
libKEDF: An accelerated library of kinetic energy density functionals.
Dieterich, Johannes M; Witt, William C; Carter, Emily A
2017-06-30
Kinetic energy density functionals (KEDFs) approximate the kinetic energy of a system of electrons directly from its electron density. They are used in electronic structure methods that lack direct access to orbitals, for example, orbital-free density functional theory (OFDFT) and certain embedding schemes. In this contribution, we introduce libKEDF, an accelerated library of modern KEDF implementations that emphasizes nonlocal KEDFs. We discuss implementation details and assess the performance of the KEDF implementations for large numbers of atoms. We show that using libKEDF, a single computing node or (GPU) accelerator can provide easy computational access to mesoscale chemical and materials science phenomena using OFDFT algorithms. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.
Quantum oscillations in the kinetic energy density: Gradient corrections from the Airy gas
NASA Astrophysics Data System (ADS)
Lindmaa, Alexander; Mattsson, Ann E.; Armiento, Rickard
2014-03-01
We show how one can systematically derive exact quantum corrections to the kinetic energy density (KED) in the Thomas-Fermi (TF) limit of the Airy gas (AG). The resulting expression is of second order in the density variation and we demonstrate how it applies universally to a certain class of model systems in the slowly varying regime, for which the accuracy of the gradient corrections of the extended Thomas-Fermi (ETF) model is limited. In particular we study two kinds of related electronic edges, the Hermite gas (HG) and the Mathieu gas (MG), which are both relevant for discussing periodic systems. We also consider two systems with finite integer particle number, namely non-interacting electrons subject to harmonic confinement as well as the hydrogenic potential. Finally we discuss possible implications of our findings mainly related to the field of functional development of the local kinetic energy contribution.
Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave
Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; ...
2017-03-31
Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA’s Magnetospheric Multiscale (MMS) mission, we utilize Earth’s magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electronsmore » confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. As a result, the investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.« less
Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave
Gershman, Daniel J.; F-Viñas, Adolfo; Dorelli, John C.; Boardsen, Scott A.; Avanov, Levon A.; Bellan, Paul M.; Schwartz, Steven J.; Lavraud, Benoit; Coffey, Victoria N.; Chandler, Michael O.; Saito, Yoshifumi; Paterson, William R.; Fuselier, Stephen A.; Ergun, Robert E.; Strangeway, Robert J.; Russell, Christopher T.; Giles, Barbara L.; Pollock, Craig J.; Torbert, Roy B.; Burch, James L.
2017-01-01
Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations. PMID:28361881
NASA Astrophysics Data System (ADS)
Zilletti, Michele; Elliott, Stephen J.; Rustighi, Emiliano
2012-08-01
The tuning of a dynamic vibration absorber is considered such that either the kinetic energy of the host structure is minimised or the power dissipation within the absorber is maximised. If the host structure is approximated as a damped single degree of freedom, the optimal values for the ratio of the absorber's natural frequency to the host structure and the optimal damping ratio of the absorber are shown to be the same whether the kinetic energy of the host structure is minimised or the power dissipation of the absorber is maximised. It is also demonstrated that the total power input into the system does not depend on the two parameters but only on the host structure's mass.
Khoma, Mykhaylo; Jaquet, Ralph
2017-09-21
The kinetic energy operator for triatomic molecules with coordinate or distance-dependent nuclear masses has been derived. By combination of the chain rule method and the analysis of infinitesimal variations of molecular coordinates, a simple and general technique for the construction of the kinetic energy operator has been proposed. The asymptotic properties of the Hamiltonian have been investigated with respect to the ratio of the electron and proton mass. We have demonstrated that an ad hoc introduction of distance (and direction) dependent nuclear masses in Cartesian coordinates preserves the total rotational invariance of the problem. With the help of Wigner rotation functions, an effective Hamiltonian for nuclear motion can be derived. In the derivation, we have focused on the effective trinuclear Hamiltonian. All necessary matrix elements are given in closed analytical form. Preliminary results for the influence of non-adiabaticity on vibrational band origins are presented for H3(+).
NASA Astrophysics Data System (ADS)
Khoma, Mykhaylo; Jaquet, Ralph
2017-09-01
The kinetic energy operator for triatomic molecules with coordinate or distance-dependent nuclear masses has been derived. By combination of the chain rule method and the analysis of infinitesimal variations of molecular coordinates, a simple and general technique for the construction of the kinetic energy operator has been proposed. The asymptotic properties of the Hamiltonian have been investigated with respect to the ratio of the electron and proton mass. We have demonstrated that an ad hoc introduction of distance (and direction) dependent nuclear masses in Cartesian coordinates preserves the total rotational invariance of the problem. With the help of Wigner rotation functions, an effective Hamiltonian for nuclear motion can be derived. In the derivation, we have focused on the effective trinuclear Hamiltonian. All necessary matrix elements are given in closed analytical form. Preliminary results for the influence of non-adiabaticity on vibrational band origins are presented for H3+.
The onset of sediment transport in vegetated channels predicted by turbulent kinetic energy
NASA Astrophysics Data System (ADS)
Yang, J. Q.; Chung, H.; Nepf, H. M.
2016-11-01
This laboratory study advances our understanding of sediment transport in vegetated regions, by describing the impact of stem density on the critical velocity, Ucrit, at which sediment motion is initiated. Sparse emergent vegetation was modeled with rigid cylinders arranged in staggered arrays of different stem densities. The sediment transport rate, Qs, was measured over a range of current speeds using digital imaging, and the critical velocity was selected as the condition at which the magnitude of Qs crossed the noise threshold. For both grain sizes considered here (0.6-0.85 mm and 1.7-2 mm), Ucrit decreased with increasing stem density. This dependence can be explained by a threshold condition based on turbulent kinetic energy, kt, suggesting that near-bed turbulence intensity may be a more important control than bed shear stress on the initiation of sediment motion. The turbulent kinetic energy model unified the bare bed and vegetated channel measurements.
Wave-particle energy exchange directly observed in a kinetic Alfvén-branch wave.
Gershman, Daniel J; F-Viñas, Adolfo; Dorelli, John C; Boardsen, Scott A; Avanov, Levon A; Bellan, Paul M; Schwartz, Steven J; Lavraud, Benoit; Coffey, Victoria N; Chandler, Michael O; Saito, Yoshifumi; Paterson, William R; Fuselier, Stephen A; Ergun, Robert E; Strangeway, Robert J; Russell, Christopher T; Giles, Barbara L; Pollock, Craig J; Torbert, Roy B; Burch, James L
2017-03-31
Alfvén waves are fundamental plasma wave modes that permeate the universe. At small kinetic scales, they provide a critical mechanism for the transfer of energy between electromagnetic fields and charged particles. These waves are important not only in planetary magnetospheres, heliospheres and astrophysical systems but also in laboratory plasma experiments and fusion reactors. Through measurement of charged particles and electromagnetic fields with NASA's Magnetospheric Multiscale (MMS) mission, we utilize Earth's magnetosphere as a plasma physics laboratory. Here we confirm the conservative energy exchange between the electromagnetic field fluctuations and the charged particles that comprise an undamped kinetic Alfvén wave. Electrons confined between adjacent wave peaks may have contributed to saturation of damping effects via nonlinear particle trapping. The investigation of these detailed wave dynamics has been unexplored territory in experimental plasma physics and is only recently enabled by high-resolution MMS observations.
The kinetics of thermal stress induced denaturation of Aquaporin 0.
Hansen, John E; Leslie, Logan; Swamy-Mruthinti, Satyanarayana
2014-08-08
Aquaporin 0 (AQP0) is an integral membrane protein that facilitates water transport and cellular adhesion in the lens. Its dysfunction has been associated with cataractogenesis. Our earlier studies showed AQP0 undergoes aggregation when subjected to thermal stress and this aggregation seems to have been facilitated by mechanical agitation brought about by gentle stirring. The purpose of this study is to determine the secondary structural changes that precede aggregation and the role that α-crystallin plays in inhibiting those structural changes. Detergent solubilized calf lens AQP0 was subjected to thermal stress at 50°C for varying times. Secondary structural changes were measured by Circular Dichroism (CD) spectropolarimetry. Convex constraint analysis was used to deconvolute the CD spectra into pure component curves representing the secondary structural elements. Our results showed that under thermal stress, the α-helix content of AQP0 decreased from 50% to 7% with a concomitant increase from 0% to 52% in β-sheet content. The time-dependent loss of α-helical structure and gain of β-sheet structure appear to follow first-order kinetics with very similar values (∼30min) suggesting a single transition. In the presence of α-crystallin, this conversion to β-sheet is minimized, suggesting that the protein structure that binds to the molecular chaperone is mostly the α-helical structure of AQP0. Copyright © 2014 Elsevier Inc. All rights reserved.
Decadal variations of the South Tropical Countercurrent and Eddy Kinetic Energy in the South Pacific
NASA Astrophysics Data System (ADS)
Rieck, Jan Klaus; Böning, Claus W.; Greatbatch, Richard J.
2017-04-01
A series of eddying global ocean-sea ice models is used to assess the low-frequency variability of Eddy Kinetic Energy in the world ocean. The models with horizontal resolutions ranging from 1/4°-1/12° are driven by the atmospheric CORE.v2 forcing for a period of 1958-2009. A region located between 25°-33°S and 153°-175°W stands out globally, having a high variance of EKE, relative to the mean EKE, at decadal timescales. This region is characterized by the shallow, eastward South Tropical Countercurrent (STCC). The STCC, restricted to the upper 200m, forms a vertically sheared current system with the westward South Equatorial Current (SEC) below. While there are only minor changes to the SEC on decadal timescales, velocities of the STCC vary with a magnitude of >50% of the mean. The induced variations in vertical shear (du/dz) are at a maximum during the 1970s, followed by a minimum from the mid 1980s to mid 1990s and a subsequent increase. Decadal EKE changes are driven by these variations in du/dz and an associated strengthening of the reversal of the meridional gradient of potential vorticity with depth. Increased du/dz between the STCC and SEC is related, through the thermal wind balance, to sub-surface temperature anomalies, with a maximum >1°C at 300m depth. Sensitivity studies reveal this decadal variations to be driven by changes in the wind stress τ. A combination of local and remote anomalies of curl(τ) drives sub-surface temperature changes that either emerge locally or propagate in to the STCC region from the east and south. These temperature anomalies steepen (flatten) the isopycnals and increase (decrease) du/dz.
Nonlinear Cascades of Surface Oceanic Geostrophic Kinetic Energy in the Frequency Domain
2012-09-01
1986: Numerical simulations of the vertical structure of quasi - geostrophic turbulence. / At- mos. ScL, 43,2923-2936. Hughes, C. W., and S. D. P...Phys. Oceanogr.. 34,416-431 Salmon, R., 1978: Two-layer quasi - geostrophic turbulence in a simple special case. Geophys. Astrophys. Fluid Dyn...AUTHORISI Nonlinear Cascades of Surface Oceanic Geostrophic Kinetic Energy in the Frequency Domain 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK
Nonlinear Cascades of Surface Oceanic Geostrophic Kinetic Energy in the Frequency Domain
2012-09-01
B I C E T A L . 1599 Hua, B. L., and D. B. Haidvogel, 1986: Numerical simulations of the vertical structure of quasi - geostrophic turbulence. J. At...equilibration of an oceanic baroclinic jet. J. Phys. Oceanogr., 34, 416–432. Salmon, R., 1978: Two-layer quasi - geostrophic turbulence in a simple...Nonlinear Cascades of Surface Oceanic Geostrophic Kinetic Energy in the Frequency Domain* BRIAN K. ARBIC Department of Earth and Environmental
Budget of Turbulent Kinetic Energy in a Shock Wave Boundary-Layer Interaction
NASA Technical Reports Server (NTRS)
Vyas, Manan; Waindim, Mbu; Gaitonde, Datta
2016-01-01
Implicit large-eddy simulation (ILES) of a shock wave boundary-layer interaction (SBLI) was performed. Quantities present in the exact equation of the turbulent kinetic energy (TKE) transport were accumulated. These quantities will be used to calculate the components of TKE-like production, dissipation, transport, and dilatation. Correlations of these terms will be presented to study the growth and interaction between various terms. A comparison with its RANS (Reynolds-Averaged Navier-Stokes) counterpart will also be presented.
Revisiting the density scaling of the non-interacting kinetic energy.
Borgoo, Alex; Teale, Andrew M; Tozer, David J
2014-07-28
Scaling relations play an important role in the understanding and development of approximate functionals in density functional theory. Recently, a number of these relationships have been redefined in terms of the Kohn-Sham orbitals [Calderín, Phys. Rev. A: At., Mol., Opt. Phys., 2013, 86, 032510]. For density scaling the author proposed a procedure involving a multiplicative scaling of the Kohn-Sham orbitals whilst keeping their occupation numbers fixed. In the present work, the differences between this scaling with fixed occupation numbers and that of previous studies, where the particle number change implied by the scaling was accommodated through the use of the grand canonical ensemble, are examined. We introduce the terms orbital and ensemble density scaling for these approaches, respectively. The natural ambiguity of the density scaling of the non-interacting kinetic energy functional is examined and the ancillary definitions implicit in each approach are highlighted and compared. As a consequence of these differences, Calderín recovered a homogeneity of degree 1 for the non-interacting kinetic energy functional under orbital scaling, contrasting recent work by the present authors [J. Chem. Phys., 2012, 136, 034101] where the functional was found to be inhomogeneous under ensemble density scaling. Furthermore, we show that the orbital scaling result follows directly from the linearity and the single-particle nature of the kinetic energy operator. The inhomogeneity of the non-interacting kinetic energy functional under ensemble density scaling can be quantified by defining an effective homogeneity. This quantity is shown to recover the homogeneity values for important approximate forms that are exact for limiting cases such as the uniform electron gas and one-electron systems. We argue that the ensemble density scaling provides more insight into the development of new functional forms.
Intercomparison of the seasonal cycle in 200 hPa kinetic energy in AMIP GCM simulations
Boyle, J.S.
1996-10-01
The 200 hPa kinetic energy is represented by means of the spherical harmonic components for the Atmospheric Model Intercomparison Project (AMIP) simulations, the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis and the European Centre for Medium Range Weather Forecast Reanalysis (ERA). The data used are the monthly mean wind fields from 1979 to 1988. The kinetic energy is decomposed into the divergent (DKE) and rotational (RKE) components and emphasis is placed on examining the former. The two reanalysis data sets show reasonable agreement that is best for the rotational kinetic energy. The largest difference in the divergent kinetic energy occurs during the northern summer. As might be expected, the two analyses are closet in regions where there are sufficient observations such that the effect of the model used in the assimilation cycle are minimized. The observed RKE show only a slight seasonal cycle with a maximum occuring during the northern winter. The DKE, on the other hand, has a very pronounced seasonal cycle with maxima at the solsticial seasons and minima during the equinoctial seasons. The model results show a very large spread in the magnitudes of the RKE and DKE although the models all evince a seasonal variation in phase with that observed. The median values of the seasonal cycle of RKE and DKE for the models are usually superior to those of any individual model. Results are also presented for simulation following the AMIP protocol but using updated versions of the original AMIP entries. In most cases these new integrations show better agreement with the observations.
Eigenvalue spectrum of the independent-fermion kinetic-energy kernel
Joubert, D.
1996-09-01
The constrained minimization independent-fermion kinetic-energy kernel, {delta}{sup 2}{ital T}{sub {ital s}}[{rho}]/{delta}{rho}({bold r}){delta}{rho}({bold r}{sup {prime}}), has a zero mode for all {rho}({bold r}), while it is non-negative for {rho}({bold r}) noninteracting {ital v} representable. {copyright} {ital 1996 The American Physical Society.}
Initiation and Modification of Reaction by Energy Addition: Kinetic and Transport Phenomena
1993-10-01
MODIFICATION OF REACTION BY ENERGY ADDITION: KINETIC AND TRANSPORT PHENOMENA by Francis E. Fendell and Mau-Song Chou Center for Propulsion Technology...TA - A2 L AUHOWAC - F49620-90-C-0070 Francis E. Fendell and Mau-Song Chou 7. PEMOS101IG ORGANIZATION NAME(S AND...a gaseous mixture is more pertinent for the supersonic-combustor applications of interest to the Air Force (compare Figs. 1 and 2) (Carrier, Fendell
State-to-State Internal Energy Relaxation Following the Quantum-Kinetic Model in DSMC
NASA Technical Reports Server (NTRS)
Liechty, Derek S.
2014-01-01
A new model for chemical reactions, the Quantum-Kinetic (Q-K) model of Bird, has recently been introduced that does not depend on macroscopic rate equations or values of local flow field data. Subsequently, the Q-K model has been extended to include reactions involving charged species and electronic energy level transitions. Although this is a phenomenological model, it has been shown to accurately reproduce both equilibrium and non-equilibrium reaction rates. The usefulness of this model becomes clear as local flow conditions either exceed the conditions used to build previous models or when they depart from an equilibrium distribution. Presently, the applicability of the relaxation technique is investigated for the vibrational internal energy mode. The Forced Harmonic Oscillator (FHO) theory for vibrational energy level transitions is combined with the Q-K energy level transition model to accurately reproduce energy level transitions at a reduced computational cost compared to the older FHO models.
Kinetic Energy Distribution of H(2p) Atoms from Dissociative Excitation of H2
NASA Technical Reports Server (NTRS)
Ajello, Joseph M.; Ahmed, Syed M.; Kanik, Isik; Multari, Rosalie
1995-01-01
The kinetic energy distribution of H(2p) atoms resulting from electron impact dissociation of H2 has been measured for the first time with uv spectroscopy. A high resolution uv spectrometer was used for the measurement of the H Lyman-alpha emission line profiles at 20 and 100 eV electron impact energies. Analysis of the deconvolved 100 eV line profile reveals the existence of a narrow line peak and a broad pedestal base. Slow H(2p) atoms with peak energy near 80 meV produce the peak profile, which is nearly independent of impact energy. The wings of H Lyman-alpha arise from dissociative excitation of a series of doubly excited Q(sub 1) and Q(sub 2) states, which define the core orbitals. The fast atom energy distribution peaks at 4 eV.
Systematics of kinetic freeze-out properties in high energy collisions from STAR
NASA Astrophysics Data System (ADS)
Kumar, Lokesh
2014-11-01
The main aim of the RHIC Beam Energy Scan (BES) program is to explore the QCD phase diagram which includes search for a possible QCD critical point and the phase boundary between QGP and hadronic phase. We report the collision energy and centrality dependence of kinetic freeze-out properties from the measured mid-rapidity (| y | < 0.1) light hadrons (pions, kaons, protons and their anti-particles) for Au + Au collisions at the center-of-mass energy √{sNN} = 7.7 , 11.5 , 19.6 , 27 , and 39 GeV. The STAR detector, with a large uniform acceptance and excellent particle identification is used in the data collection and analysis. The kinetic freeze-out temperature Tkin and average collective velocity < β > parameters are extracted from blast-wave fits to the identified hadron spectra and systematically compared with the results from other collision energies including those at AGS, SPS and LHC. It is found that all results fall into an anti-correlation band in the 2-dimensional (Tkin, < β >) distribution: the largest value of collective velocity and lowest temperature is reached in the most central collisions at the highest collision energy. The energy dependence of these freeze-out parameters is discussed.
Recruiting at the Edge: Kinetic Energy Inhibits Anchovy Populations in the Western Mediterranean
Ruiz, Javier; Macías, Diego; Rincón, Margarita M.; Pascual, Ananda; Catalán, Ignacio A.; Navarro, Gabriel
2013-01-01
The Strait of Gibraltar replenishes the Mediterranean with Atlantic waters through an intense eastward current known as the Atlantic Jet (AJ). The AJ fertilizes the southwestern Mediterranean and is considered to be the ultimate factor responsible for the comparatively high fish production of this region. Here, we perform an analysis of the available historical catches and catch per unit effort (CPUE), together with a long series of surface currents, kinetic energy and chlorophyll concentration. We show that the high kinetic energy of the AJ increases primary production but also negatively impacts the recruitment of anchovy. We contend that anchovy recruitment in the region is inhibited by the advection and dispersion of larvae and post-larvae during periods of strong advection by the AJ. The inhibitory impact of kinetic energy on anchovy landings is not a transient but rather a persistent state of the system. An exceptional combination of events creates an outbreak of this species in the Alboran Sea. These events depend on the Mediterranean-Atlantic exchange of water masses and, therefore, are highly sensitive to climate changes that are projected, though not always negatively, for fish landings. PMID:23451027
Quasiperiodic energy dependence of exciton relaxation kinetics in the sexithiophene crystal.
Petelenz, Piotr; Zak, Emil
2014-10-16
Femtosecond kinetics of fluorescence rise in the sexithiophene crystal is studied on a microscopic model of intraband relaxation, where exciton energy is assumed to be dissipated by phonon-accompanied scattering, with the rates calculated earlier. The temporal evolution of the exciton population is described by a set of kinetic equations, solved numerically to yield the population buildup at the band bottom. Not only the time scale but also the shape of the rise curves is found to be unusually sensitive to excitation energy, exhibiting unique quasiperiodic dependence thereon, which is rationalized in terms of the underlying model. Further simulations demonstrate that the main conclusions are robust with respect to experimental factors such as finite temperature and inherent spectral broadening of the exciting pulse, while the calculated fluorescence rise times are found to be in excellent agreement with experimental data available to date. As the rise profiles are composed of a number of exponential contributions, which varies with excitation energy, the common practice of characterizing the population buildup in the emitting state by a single value of relaxation time turns out to be an oversimplification. New experiments giving further insight into the kinetics and mechanism of intraband exciton relaxation are suggested.
Nucleation of diindenoperylene and pentacene at thermal and hyperthermal incident kinetic energies
Kish, Edward R.; Desai, Tushar V.; Greer, Douglas R.; Engstrom, James R.; Woll, Arthur R.
2015-05-15
The authors have examined the nucleation of diindenoperylene (DIP) on SiO{sub 2} employing primarily atomic force microscopy and focusing on the effect of incident kinetic energy employing both thermal and supersonic sources. For all incident kinetic energies examined (E{sub i} = 0.09–11.3 eV), the nucleation of DIP is homogeneous and the dependence of the maximum island density on the growth rate is described by a power law. A critical nucleus of approximately two molecules is implicated by our data. A re-examination of the nucleation of pentacene on SiO{sub 2} gives the same major result that the maximum island density is determined by the growth rate, and it is independent of the incident kinetic energy. These observations are readily understood by factoring in the size of the critical nucleus in each case, and the island density, which indicates that diffusive transport of molecules to the growing islands dominate the dynamics of growth in the submonolayer regime.
Kinetic Energy and Angular Distributions of He and Ar Atoms Evaporating from Liquid Dodecane.
Patel, Enamul-Hasan; Williams, Mark A; Koehler, Sven P K
2017-01-12
We report both kinetic energy and angular distributions for He and Ar atoms evaporating from C12H26. All results were obtained by performing molecular dynamics simulations of liquid C12H26 with around 10-20 noble gas atoms dissolved in the liquid and by subsequently following the trajectories of the noble gas atoms after evaporation from the liquid. Whereas He evaporates with a kinetic energy distribution of (1.05 ± 0.03) × 2RT (corrected for the geometry used in experiments: (1.08 ± 0.03) × 2RT, experimentally obtained value: (1.14 ± 0.01) × 2RT), Ar displays a kinetic energy distribution that better matches a Maxwell-Boltzmann distribution at the temperature of the liquid ((0.99 ± 0.04) × 2RT). This behavior is also reflected in the angular distributions, which are close to a cosine distribution for Ar but slightly narrower, especially for faster atoms, in the case of He. This behavior of He is most likely due to the weak interaction potential between He and the liquid hydrocarbon.
How is initial soil erosion affected by rainfall intensity and kinetic energy?
NASA Astrophysics Data System (ADS)
Neumann, Martin; Iserloh, Thomas; Rodrigo Comino, Jesús; Kavka, Petr; Seeger, Manuel; Ries, Johannes B.
2017-04-01
Rainfall simulation with small scale simulators is a method used worldwide to assess the generation of overland flow and initial soil erosion. For a thorough interpretation of the obtained experimental data, it is necessary to know detailed information of the rainfall characteristics. This study presents the effect of different rainfall intensities and kinetic energies on initial soil erosion rates under controlled experimental conditions. For this research the small portable rainfall simulator of Trier University was used. The experimental plot is 0.28 m2 and the height of the nozzle is 2 m above ground. We applied a wide range of rainfall intensities (20, 40, 60 and 80 mm h-1) and kinetic energies (0.4 - 9 J m2 mm-1). For this purpose, a set of various nozzles were tested under laboratory conditions. First, the spatial distribution of the artificial rainfall on the plot surface was measured to ensure the reproducibility of the experiments with constant rainfall intensity. Second, the drop size distribution was tested to control and adjust its similarity to the one measured in natural events. With the selected nozzles and rainfall intensities, 54 rainfall simulations were performed on prepared surface at the experimental site of Trier University. With the measured values a 3D matrix of rainfall intensity, kinetic energy and soil loss were calculated. This method allows an accurate estimation of soil erodibility for a wide range of rainfall characteristics. The presentation was funded by Ministry of agriculture of the Czech Republic (research project QJ1520265).
Measuring kinetic energy changes in the mesoscale with low acquisition rates
Roldán, É.; Martínez, I. A.; Rica, R. A.; Dinis, L.
2014-06-09
We report on the measurement of the average kinetic energy changes in isothermal and non-isothermal quasistatic processes in the mesoscale, realized with a Brownian particle trapped with optical tweezers. Our estimation of the kinetic energy change allows to access to the full energetic description of the Brownian particle. Kinetic energy estimates are obtained from measurements of the mean square velocity of the trapped bead sampled at frequencies several orders of magnitude smaller than the momentum relaxation frequency. The velocity is tuned applying a noisy electric field that modulates the amplitude of the fluctuations of the position and velocity of the Brownian particle, whose motion is equivalent to that of a particle in a higher temperature reservoir. Additionally, we show that the dependence of the variance of the time-averaged velocity on the sampling frequency can be used to quantify properties of the electrophoretic mobility of a charged colloid. Our method could be applied to detect temperature gradients in inhomogeneous media and to characterize the complete thermodynamics of biological motors and of artificial micro and nanoscopic heat engines.
NASA Astrophysics Data System (ADS)
van Bohemen, S. M. C.
2015-01-01
The kinetics of the martensitic transformation in Fe-0.80C determined on the basis of dilatometry data is compared to the acoustic emission (AE) energy accompanying the transformation in the same steel reported in a previous study. The discrepancy between the AE energy and the volume fraction of martensite indicates that the mechanism for the generation of AE during the martensitic transformation is not solely dependent on the kinetics and the associated moving interfaces as suggested in previous studies. During the growth of martensite, slip takes place in order to relieve internal stresses, and dislocations are thought to be mainly introduced in the relatively soft austenite matrix. The quantitative analysis in this study demonstrates that the AE energy generated per unit time is a function of both the transformation kinetics and the volume fraction of remaining austenite. This strongly indicates that the moving dislocations associated with the plastic deformation of the austenite surrounding the as-formed martensite are the dominant sources of the generated acoustic waves. This improved AE source model is consistent with the well-accepted mechanism of AE during conventional plastic deformation due to an external load.
Dissipation of Turbulent Kinetic Energy in the Atmospheric Boundary Layer: Observations and Theory
NASA Astrophysics Data System (ADS)
Blumen, W.
2002-05-01
Two aspects of atmospheric dissipation will be examined, namely, the measurement of dissipation in frontal zones that are embedded in the boundary layer, and a theoretical examination of the dissipation length, used for parameterization purposes in some numerical models. The observations were acquired during two field programs carried out in southeast Kansas:MICROFRONTS-1995 and CASES-1999. Data were collected by both hot-wire and sonic anemometers. The hot-wire voltages were converted to wind speeds and the dissipation computed under the assumption of local isotropy. Taylor's hypothesis, including correction terms, was applied to convert spatial to time derivatives, since these data were collected on towers and presented as time series. This approach represents the direct dissipation method. The inertial method computes the dissipation from inertial subrange measurements, making use of the Kolmogorov five-thirds law and Taylor's hypothesis. The turbulent kinetic energy dissipation rate ɛ increased by over an order of magnitude in the frontal zone that passed the MICROFRONTS tower array, from values of the order of ɛ =0.01m2s-3 in the prefrontal region. After passage of the front the dissipation rate relaxed back to prefrontal values. The dissipation rate within the frontal zone that passed through the CASES site could not be determined because of flow distortion by the tower. Both prefrontal and post frontal dissipation rates were similar in magnitude to those measured during MICROFRONTS.In each case, no significant differences in the magnitudes of ɛ determined by the direct dissipation and inertial dissipation calculations, were evident. Numerical models require a parameterization of the dissipation rate ɛ that is appropriate for the unresolved scales of motion. One approach is to employ the dissipation length l as a surrogate for ɛ , where l=e3/2/ɛ and e is the turbulent kinetic energy. The aim is to represent l as a function of the vertical wind shear and
Mass Yields and Average Total Kinetic Energy Release in Fission for 235U, 238U, and 239Pu
NASA Astrophysics Data System (ADS)
Duke, Dana
2015-10-01
Mass yield distributions and average total kinetic energy (TKE) in neutron induced fission of 235U, 238U, and 239Pu targets were measured with a gridded ionization chamber. Despite decades of fission research, our understanding of how fragment mass yields and TKE depend on incident neutron energy is limited, especially at higher energies (above 5-10 MeV). Improved accuracy in these quantities is important for nuclear technology as it enhances our simulation capabilities and increases the confidence in diagnostic tools. The data can also guide and validate theoretical fission models where the correlation between the fragment mass and TKE is of particular value for constraining models. The Los Alamos Neutron Science Center - Weapons Neutron Research (LANSCE - WNR) provides a neutron beam with energies from thermal to hundreds of MeV, well-suited for filling in the gaps in existing data and exploring fission behavior in the fast neutron region. The results of the studies on target nuclei 235U, 238U, and 239Pu will be presented with a focus on exploring data trends as a function of neutron energy from thermal through 30 MeV. Results indicate clear evidence of structure due to multi-chance fission in the TKE . LA-UR-15-24761.
Berkane, K.; Bencheikh, K.
2005-08-15
For first-principles density functional theory of a many fermion system, the determination of the kinetic energy functional is important. We consider N independent fermions with spatially varying effective mass in two dimensions, we derive the corresponding kinetic energy density using the ({Dirac_h}/2{pi}) semiclassical approach. Our result reduces, as expected, to the one obtained in the literature for a constant effective mass. We examine the analytical expressions of the position dependent effective mass terms in the kinetic energy density functional with respect to the dimensionality d=1,2,3 of the space.
NASA Astrophysics Data System (ADS)
Di Palma, T. M.; Apicella, B.; Armenante, M.; Velotta, R.; Wang, X.; Spinelli, N.
2005-11-01
The kinetic energy distributions and the cross sections of the ions produced in the electron impact of ethyl tert-butyl ether (ETBE) have been studied by time of flight (TOF) mass spectrometry. The kinetic energy distributions have been deduced from the TOF peak shape analysis and a Montecarlo simulation method of the ion trajectories has been used to evaluate the collection efficiency of the spectrometer as a function of the ion initial kinetic energy. The measured ion yields have been corrected for the collection efficiency and the partial and total ionization cross sections of ETBE determined in the range 20-150 eV.
Che, H; Goldstein, M L; Viñas, A F
2014-02-14
The observed steep kinetic scale turbulence spectrum in the solar wind raises the question of how that turbulence originates. Observations of keV energetic electrons during solar quiet time suggest them as a possible source of free energy to drive kinetic turbulence. Using particle-in-cell simulations, we explore how the free energy released by an electron two-stream instability drives Weibel-like electromagnetic waves that excite wave-wave interactions. Consequently, both kinetic Alfvénic and whistler turbulence are excited that evolve through inverse and forward magnetic energy cascades.
Orbital-free kinetic-energy density functionals with a density-dependent kernel
NASA Astrophysics Data System (ADS)
Wang, Yan Alexander; Govind, Niranjan; Carter, Emily A.
1999-12-01
We report linear-response kinetic-energy density functionals, which show significant improvement over the Wang-Teter, Perrot, Smargiassi-Madden, Wang-Govind-Carter functionals, yet still maintain O(N ln N) scaling. Numerical tests show that these functionals, which contain a double-density-dependent kernel, can reproduce the Kohn-Sham results almost exactly for several aluminum bulk phases. We further show that with a sensible choice of the uniform background density, energies of formation for the low-index aluminum surfaces, where the density variations are very large, can be reproduced to within reasonable accuracy.
NASA Astrophysics Data System (ADS)
Zhang, Zhedong; Wang, Jin
2015-04-01
We develop a population and flux landscape theory for general non-equilibrium quantum systems. We illustrate our theory by modelling the quantum transport of donor-acceptor energy transfer. We find two driving forces for the non-equilibrium quantum dynamics. The symmetric part of the driving force corresponds to the population landscape contribution which mainly governs the equilibrium part of dynamics while the anti-symmetric part of the driving force generates the non-equilibrium curl quantum flux which leads to the detailed-balance-breaking and time-irreversibility. The multi-loop structure of the flux emerges forms the flux-landscape. We study the trend of changes in population and flux-landscape with respect to the voltage (temperature difference induced by environments) and electronic coupling. Improving the voltage and electronic coupling in general facilitates the quantum transport by reducing the population landscape barriers between major states and increasing the mean value of the flux. A limit-cycle mode emerges when the underlying flux-landscape becomes funnelled with a significant gap between the largest flux loop and the rest of them. On the kinetic level, we find that multiple kinetic paths between quantum states emerge and illustrate the interference effects. The degree of interference is determined by the landscape and flux. Furthermore, we quantify kinetic rate which strongly correlates with the population landscape and flux. For quantum transport, we demonstrate that as the coherence or the quantum entanglement is enhanced, the flux and energy transfer efficiency are increased. Finally it is surprising that the non-equilibriumness quantified by voltage has a non-trivial contribution on strengthening the entanglement, which is attributed to the non-local feature of the quantum curl flux.
NASA Astrophysics Data System (ADS)
Shin, Seungha
All energy conversion inefficiencies begin with emission of resonant atomic motions, e.g., vibrations, and are declared as waste heat once these motions thermalize to equilibrium. The nonequilibrium energy occupancy of the vibrational modes can be targeted as a harvestable, low entropy energy source for direct conversion to electric energy. Since the lifetime of these resonant vibrations is short, special nanostructures are required with the appropriate tuning of the kinetics. These in turn require multiscale, multiphysics treatments. Atomic vibration is described with quasiparticle phonon in solid, and the optical phonon emission is dominant relaxation channel in semiconductors. These optical modes become over-occupied when their emission rate becomes larger than their decay rate, thus hindering energy relaxation and transport in devices. Effective removal of these phonons by drifting electrons is investigated by manipulating the electron distribution to have higher population in the low-energy states, thus allowing favorable phonon absorption. This is done through introduction, design and analysis of a heterobarrier conducting current, where the band gap is controlled by alloying, thus creating a spatial variation which is abrupt followed by a linear gradient (to ensure directed current). Self-consistent ensemble Monte Carlo simulations based on interaction kinetics between electron and phonon show that up to 19% of the phonon energy is converted to electric potential with an optimized GaAs/AlxGa1-xAs barrier structure over a range of current and electron densities, and this system is also verified through statistical entropy analysis. This direct energy conversion improves the device performance with lower operation temperature and enhances overall energy conversion efficiency. Through this study, the paradigm for harvesting the resonant atomic vibration is proposed, reversing the general role of phonon as only causing electric potential drop. Fundamentals
Liu, Guanlin; Leng, Qiang; Lian, Jiawei; Guo, Hengyu; Yi, Xi; Hu, Chenguo
2015-01-21
Great attention has been paid to nanogenerators that harvest energy from ambient environments lately. In order to give considerable output current, most nanogenerators require high-velocity motion that in most cases can hardly be provided in our daily life. Here we report a notepad-like triboelectric generator (NTEG), which uses simple notepad-like structure to generate elastic deformation so as to turn a low-velocity kinetic energy into high-velocity kinetic energy through the conversion of elastic potential energy. Therefore, the NTEG can achieve high current output under low-velocity motion, which completely distinguishes it from tribogenerators previously reported. The factors that may affect the output performance are explored, including the number of slices, active length of slice, press speed, and vertical displacement. In addition, the working mechanism is systematically studied, indicating that the efficiency of the generator can be greatly enhanced by interconversion between kinetic energy and elastic potential energy. The short-circuit current, the open-circuit voltage, and power density are 205 μA and 470 V and 9.86 W/m(2), respectively, which is powerful enough to light up hundreds of light-emitting diodes (LEDs) and charge a commercial capacitor. Besides, NTEGs have been successfully applied to a self-powered door monitor.
Kinetic energy partition method applied to ground state helium-like atoms
NASA Astrophysics Data System (ADS)
Chen, Yu-Hsin; Chao, Sheng D.
2017-03-01
We have used the recently developed kinetic energy partition (KEP) method to solve the quantum eigenvalue problems for helium-like atoms and obtain precise ground state energies and wave-functions. The key to treating properly the electron-electron (repulsive) Coulomb potential energies for the KEP method to be applied is to introduce a "negative mass" term into the partitioned kinetic energy. A Hartree-like product wave-function from the subsystem wave-functions is used to form the initial trial function, and the variational search for the optimized adiabatic parameters leads to a precise ground state energy. This new approach sheds new light on the all-important problem of solving many-electron Schrödinger equations and hopefully opens a new way to predictive quantum chemistry. The results presented here give very promising evidence that an effective one-electron model can be used to represent a many-electron system, in the spirit of density functional theory.
Kinetic energy partition method applied to ground state helium-like atoms.
Chen, Yu-Hsin; Chao, Sheng D
2017-03-28
We have used the recently developed kinetic energy partition (KEP) method to solve the quantum eigenvalue problems for helium-like atoms and obtain precise ground state energies and wave-functions. The key to treating properly the electron-electron (repulsive) Coulomb potential energies for the KEP method to be applied is to introduce a "negative mass" term into the partitioned kinetic energy. A Hartree-like product wave-function from the subsystem wave-functions is used to form the initial trial function, and the variational search for the optimized adiabatic parameters leads to a precise ground state energy. This new approach sheds new light on the all-important problem of solving many-electron Schrödinger equations and hopefully opens a new way to predictive quantum chemistry. The results presented here give very promising evidence that an effective one-electron model can be used to represent a many-electron system, in the spirit of density functional theory.
Chemical bond as a test of density-gradient expansions for kinetic and exchange energies
Perdew, J.P.; Levy, M.; Painter, G.S.; Wei, S.; Lagowski, J.B.
1988-01-15
Errors in kinetic and exchange contributions to the molecular bonding energy are assessed for approximate density functionals by reference to near-exact Hartree-Fock values. From the molecular calculations of Allan et al. and of Lee and Ghosh, it is demonstrated that the density-gradient expansion does not accurately describe the noninteracting kinetic contribution to the bonding energy, even when this expansion is carried to fourth order and applied in its spin-density-functional form to accurate Hartree-Fock densities. In a related study, it is demonstrated that the overbinding of molecules such as N/sub 2/ and F/sub 2/, which occurs in the local-spin-density (LSD) approximation for the exchange-correlation energy, is not attributable to errors in the self-consistent LSD densities. Contrary to expectations based upon the Gunnarsson-Jones nodality argument, it is found that the LSD approximation for the exchange energy can seriously overbind a molecule even when bonding does not create additional nodes in the occupied valence orbitals. LSD and exact values for the exchange contribution to the bonding energy are displayed and discussed for several molecules.
Liu, Yan; Song, Yang; Madahar, Vipul; Liao, Jiayu
2012-03-01
Förster resonance energy transfer (FRET) technology has been widely used in biological and biomedical research, and it is a very powerful tool for elucidating protein interactions in either dynamic or steady state. SUMOylation (the process of SUMO [small ubiquitin-like modifier] conjugation to substrates) is an important posttranslational protein modification with critical roles in multiple biological processes. Conjugating SUMO to substrates requires an enzymatic cascade. Sentrin/SUMO-specific proteases (SENPs) act as an endopeptidase to process the pre-SUMO or as an isopeptidase to deconjugate SUMO from its substrate. To fully understand the roles of SENPs in the SUMOylation cycle, it is critical to understand their kinetics. Here, we report a novel development of a quantitative FRET-based protease assay for SENP1 kinetic parameter determination. The assay is based on the quantitative analysis of the FRET signal from the total fluorescent signal at acceptor emission wavelength, which consists of three components: donor (CyPet-SUMO1) emission, acceptor (YPet) emission, and FRET signal during the digestion process. Subsequently, we developed novel theoretical and experimental procedures to determine the kinetic parameters, k(cat), K(M), and catalytic efficiency (k(cat)/K(M)) of catalytic domain SENP1 toward pre-SUMO1. Importantly, the general principles of this quantitative FRET-based protease kinetic determination can be applied to other proteases. Copyright Â© 2011 Elsevier Inc. All rights reserved.
Convective kinetic energy equation under the mass-flux subgrid-scale parameterization
NASA Astrophysics Data System (ADS)
Yano, Jun-Ichi
2015-03-01
The present paper originally derives the convective kinetic energy equation under mass-flux subgrid-scale parameterization in a formal manner based on the segmentally-constant approximation (SCA). Though this equation is long since presented by Arakawa and Schubert (1974), a formal derivation is not known in the literature. The derivation of this formulation is of increasing interests in recent years due to the fact that it can explain basic aspects of the convective dynamics such as discharge-recharge and transition from shallow to deep convection. The derivation is presented in two manners: (i) for the case that only the vertical component of the velocity is considered and (ii) the case that both the horizontal and vertical components are considered. The equation reduces to the same form as originally presented by Arakwa and Schubert in both cases, but with the energy dissipation term defined differently. In both cases, nevertheless, the energy "dissipation" (loss) term consists of the three principal contributions: (i) entrainment-detrainment, (ii) outflow from top of convection, and (iii) pressure effects. Additionally, inflow from the bottom of convection contributing to a growth of convection is also formally counted as a part of the dissipation term. The eddy dissipation is also included for a completeness. The order-of-magnitude analysis shows that the convective kinetic energy "dissipation" is dominated by the pressure effects, and it may be approximately described by Rayleigh damping with a constant time scale of the order of 102-103 s. The conclusion is also supported by a supplementary analysis of a cloud-resolving model (CRM) simulation. The Appendix discusses how the loss term ("dissipation") of the convective kinetic energy is qualitatively different from the conventional eddy-dissipation process found in turbulent flows.
Theory and simulation of discrete kinetic beta induced Alfvén eigenmode in tokamak plasmas
NASA Astrophysics Data System (ADS)
Wang, X.; Zonca, F.; Chen, L.
2010-11-01
It is shown, both analytically and by numerical simulations, that, in the presence of thermal ion kinetic effects, the beta induced Alfvén eigenmode (BAE)-shear Alfvén wave continuous spectrum can be discretized into radially trapped eigenstates known as kinetic BAE (KBAE). While thermal ion compressibility gives rise to finite BAE accumulation point frequency, the discretization occurs via the finite Larmor radius and finite orbit width effects. Simulations and analytical theories agree both qualitatively and quantitatively. Simulations also demonstrate that KBAE can be readily excited by the finite radial gradients of energetic particles.
NASA Technical Reports Server (NTRS)
Jaffe, Richard L.; Pattengill, Merle D.; Schwenke, David W.
1989-01-01
Strategies for constructing global potential energy surfaces from a limited number of accurate ab initio electronic energy calculations are discussed. Generally, these data are concentrated in small regions of configuration space (e.g., in the vicinity of saddle points and energy minima) and difficulties arise in generating a potential function that is globally well-behaved. Efficient computer codes for carrying out classical trajectory calculations on vector and parallel processors are also described. Illustrations are given from recent work on the following chemical systems: Ca + HF yields CaF + H, H + H + H2 yields H2 + H2, N + O2 yields NO + O and O + N2 yields NO + N. The dynamics and kinetics of metathesis, dissociation, recombination, energy transfer and complex formation processes will be discussed.
Kinetic energy distributions of sputtered neutral aluminum clusters: Al--Al[sub 6
Coon, S.R.; Calaway, W.F.; Pellin, M.J. ); Curlee, G.A. . Dept. of Physics); White, J.M. . Dept. of Chemistry and Biochemistry)
1992-01-01
Neutral aluminum clusters sputtered from polycrystalline aluminum were analyzed by laser postionization time-of-flight (TOF) mass spectrometry. The kinetic energy distributions of Al through Al[sub 6] were measured by a neutrals time-of-flight technique. The interpretation of laser postionization TOF data to extract velocity and energy distributions is presented. The aluminum cluster distributions are qualitatively similar to previous copper cluster distribution measurements from our laboratory. In contrast to the steep high energy tails predicted by the single- or multiple- collision models, the measured cluster distributions have high energy power law dependences in the range of E[sup [minus]3] to E[sup [minus]4.5]. Correlated collision models may explain the substantial abundance of energetic clusters that are observed in these experiments. Possible influences of cluster fragmentation on the distributions are discussed.
Kinetic energy distributions of sputtered neutral aluminum clusters: Al--Al{sub 6}
Coon, S.R.; Calaway, W.F.; Pellin, M.J.; Curlee, G.A.; White, J.M.
1992-12-01
Neutral aluminum clusters sputtered from polycrystalline aluminum were analyzed by laser postionization time-of-flight (TOF) mass spectrometry. The kinetic energy distributions of Al through Al{sub 6} were measured by a neutrals time-of-flight technique. The interpretation of laser postionization TOF data to extract velocity and energy distributions is presented. The aluminum cluster distributions are qualitatively similar to previous copper cluster distribution measurements from our laboratory. In contrast to the steep high energy tails predicted by the single- or multiple- collision models, the measured cluster distributions have high energy power law dependences in the range of E{sup {minus}3} to E{sup {minus}4.5}. Correlated collision models may explain the substantial abundance of energetic clusters that are observed in these experiments. Possible influences of cluster fragmentation on the distributions are discussed.
NASA Technical Reports Server (NTRS)
Jaffe, Richard L.; Pattengill, Merle D.; Schwenke, David W.
1989-01-01
Strategies for constructing global potential energy surfaces from a limited number of accurate ab initio electronic energy calculations are discussed. Generally, these data are concentrated in small regions of configuration space (e.g., in the vicinity of saddle points and energy minima) and difficulties arise in generating a potential function that is globally well-behaved. Efficient computer codes for carrying out classical trajectory calculations on vector and parallel processors are also described. Illustrations are given from recent work on the following chemical systems: Ca + HF yields CaF + H, H + H + H2 yields H2 + H2, N + O2 yields NO + O and O + N2 yields NO + N. The dynamics and kinetics of metathesis, dissociation, recombination, energy transfer and complex formation processes will be discussed.
NASA Astrophysics Data System (ADS)
Salinas, V.; Bruning, E. C.; Berkseth, S.
2016-12-01
Current research for the Kinematic Texture and Lightning (KTaL) experiment seeks to provide insight on the correlation between lightning flash rate, size, and energy to the turbulent environment of thunderstorms. Previous work has shown higher and lower flash rates to correspond to smaller and larger flashes within the more or less turbulent regions of thunderstorms. The energy of these flashes were found through dimensional analysis, where the energy spectra for an ensemble of flashes showed correlation between flash size and turbulent structure. However, this flash energy was estimated without the retrieval of a self-consistent set of electrostatic parameters such as the electric field or charge density. This study uses the West Texas Lightning Mapping Array (WTLMA) to estimate the electrostatic energy and TTU Ka-band mobile radar data to estimate the turbulent kinetic energy (TKE) spectra. A 3D Poisson solver is used to find the charge density used to estimate the electrostatic energy of individual flashes for LMA generated convex hull geometries. It is hypothesized that electrostatic energy obtained from the numerical solver will covary with the energy spectra derived from dimensional analysis and the TKE spectra for each deployment, therby showing the physical link between flash size and the turbulent structure of thunderstorms.
NASA Astrophysics Data System (ADS)
Gamal, Yosr E. E.-D.; Abdellatif, Galila
2017-08-01
A study is performed to investigate the dependency of threshold intensity on gas pressure observed in the measurements of the breakdown of molecular oxygen that carried out by Phuoc (2000) [1]. In this experiment, the breakdown was induced by 532 nm laser radiation of pulse width 5.5 ns and spot size of 8.5 μm, in oxygen over a wide pressure range (190-3000 Torr). The analysis aimed to explore the electron kinetic reliance on gas pressure for the separate contribution of each of the gain and loss processes encountered in this study. The investigation is based on an electron cascade model applied previously in Gamal and Omar (2001) [2] and Gaabour et al. (2013) [3]. This model solves numerically a differential equation designates the time evolution of the electron energy distribution, and a set of rate equations that describe the change of excited states population. The numerical examination of the electron energy distribution function and its parameters revealed that photo-ionization of the excited molecules plays a significant role in enhancing the electron density growth rate over the whole tested gas pressure range. This process is off set by diffusion of electrons out of the focal volume in the low-pressure regime. At atmospheric pressure electron, collisional processes dominate and act mainly to populate the excited states. Hence photo-ionization becomes efficient and compete with the encountered loss processes (electron diffusion, vibrational excitation of the ground state molecules as well as two body attachments). At high pressures ( 3000 Torr) three body attachments are found to be the primary cause of losses which deplete the electron density and hence results in the slow decrease of the threshold intensity.
Fission induced by nucleons at intermediate energies
NASA Astrophysics Data System (ADS)
Lo Meo, S.; Mancusi, D.; Massimi, C.; Vannini, G.; Ventura, A.
2015-01-01
Monte Carlo calculations of fission of actinides and pre-actinides induced by protons and neutrons in the energy range from 100 MeV to 1 GeV are carried out by means of a recent version of the Liège Intranuclear Cascade Model, INCL++, coupled with two different evaporation-fission codes, GEMINI++ and ABLA07. In order to reproduce experimental fission cross sections, model parameters are usually adjusted on available (p , f) cross sections and used to predict (n , f) cross sections for the same isotopes.
Pan, Jianjun; Khadka, Nawal K
2016-05-26
Quantitative characterization of membrane defects (pores) is important for elucidating the molecular basis of many membrane-active peptides. We study kinetic defects induced by melittin in vesicular and planar lipid bilayers. Fluorescence spectroscopy measurements indicate that melittin induces time-dependent calcein leakage. Solution atomic force microscopy (AFM) is used to visualize melittin-induced membrane defects. After initial equilibration, the most probable defect radius is ∼3.8 nm in 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) bilayers. Unexpectedly, defects become larger with longer incubation, accompanied by substantial shape transformation. The initial defect radius is ∼4.7 nm in 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers. Addition of 30 mol % cholesterol to DOPC bilayers suppresses defect kinetics, although the inhibitory impact is negated by longer incubation. Overall, the kinetic rate of defect development follows DLPC > DOPC > DOPC/cholesterol. Kinetic defects are also observed when anionic lipids are present. Based on the observation that defects can occupy as large as 40% of the bilayer surface, we propose a kinetic defect growth model. We also study the effect of melittin on the phase behavior of DOPC/egg-sphingomyelin/cholesterol bilayers. We find that melittin initially suppresses or eliminates liquid-ordered (Lo) domains; Lo domains gradually emerge and become the dominant species with longer incubation; and defects in phase-coexisting bilayers have a most probable radius of ∼5 nm and are exclusively localized in the liquid-disordered (Ld) phase. Our experimental data highlight that melittin-induced membrane defects are not static; conversely, spontaneous defect growth is intrinsically associated with membrane permeabilization exerted by melittin.
Enzymatic Kinetic Isotope Effects from Path-Integral Free Energy Perturbation Theory.
Gao, J
2016-01-01
Path-integral free energy perturbation (PI-FEP) theory is presented to directly determine the ratio of quantum mechanical partition functions of different isotopologs in a single simulation. Furthermore, a double averaging strategy is used to carry out the practical simulation, separating the quantum mechanical path integral exactly into two separate calculations, one corresponding to a classical molecular dynamics simulation of the centroid coordinates, and another involving free-particle path-integral sampling over the classical, centroid positions. An integrated centroid path-integral free energy perturbation and umbrella sampling (PI-FEP/UM, or simply, PI-FEP) method along with bisection sampling was summarized, which provides an accurate and fast convergent method for computing kinetic isotope effects for chemical reactions in solution and in enzymes. The PI-FEP method is illustrated by a number of applications, to highlight the computational precision and accuracy, the rule of geometrical mean in kinetic isotope effects, enhanced nuclear quantum effects in enzyme catalysis, and protein dynamics on temperature dependence of kinetic isotope effects. © 2016 Elsevier Inc. All rights reserved.
Viggiano, A A
2006-06-14
A number of aspects of ionospheric chemistry are revisited. The review discusses in detail only work performed at AFRL, but other work is mentioned. A large portion of the paper discusses measurements of the kinetics of upper ionospheric reactions at very high temperatures, i.e. the upper temperature range has been extended to at least 1400 K and in some cases to 1800 K. These temperatures are high enough to excite vibrations in O2, N2, and NO and comparing them to drift tube data allows information on the rotational temperature and vibrational level dependences to be derived. Rotational and translational energy are equivalent in controlling the kinetics in most reactions. Vibrational energy in O2 and N2 is often found to promote reactivity which is shown to cause ionospheric density depletions. NO vibrations do not significantly affect the reactivity. In a number of cases, detailed calculations accompanied the experimental studies and elucidated details of the mechanisms. Kinetics of two peroxide isomers important in the lower ionospheric have been measured for the first time, i.e. NOO+ and ONOO-. Finally, two examples are shown where errors in previous data are corrected.
NASA Astrophysics Data System (ADS)
Andrianova, Z. S.; Breslavskaya, N. N.; Pliss, E. M.; Buchachenko, A. L.
2016-10-01
A computational program specially designed to analyze co-oxidation of substances in mixtures is suggested. The rigorous kinetic scheme of 32 reactions describing co-oxidation of isotope differing polyunsaturated fatty acids was computed to enlighten experimentally detected enormously large H/D isotope effects. The latter were shown to depend on the kinetic chain length and exhibit two extreme regimes of short and long chains which characterize isotope effects on the initiation and propagation chain reactions of hydrogen (deuterium) atom abstraction. No protective effect of deuterated polyunsaturated acids on the oxidation of protiated acids was detected. Protective effect of the deuterated compounds on the biologically important processes seems to be induced by the low yield of products formed in the chain termination reactions due to the low rate of initiation by deuterated compounds.
Kinetic energy distribution of multiply charged ions in Coulomb explosion of Xe clusters.
Heidenreich, Andreas; Jortner, Joshua
2011-02-21
We report on the calculations of kinetic energy distribution (KED) functions of multiply charged, high-energy ions in Coulomb explosion (CE) of an assembly of elemental Xe(n) clusters (average size (n) = 200-2171) driven by ultra-intense, near-infrared, Gaussian laser fields (peak intensities 10(15) - 4 × 10(16) W cm(-2), pulse lengths 65-230 fs). In this cluster size and pulse parameter domain, outer ionization is incomplete∕vertical, incomplete∕nonvertical, or complete∕nonvertical, with CE occurring in the presence of nanoplasma electrons. The KEDs were obtained from double averaging of single-trajectory molecular dynamics simulation ion kinetic energies. The KEDs were doubly averaged over a log-normal cluster size distribution and over the laser intensity distribution of a spatial Gaussian beam, which constitutes either a two-dimensional (2D) or a three-dimensional (3D) profile, with the 3D profile (when the cluster beam radius is larger than the Rayleigh length) usually being experimentally realized. The general features of the doubly averaged KEDs manifest the smearing out of the structure corresponding to the distribution of ion charges, a marked increase of the KEDs at very low energies due to the contribution from the persistent nanoplasma, a distortion of the KEDs and of the average energies toward lower energy values, and the appearance of long low-intensity high-energy tails caused by the admixture of contributions from large clusters by size averaging. The doubly averaged simulation results account reasonably well (within 30%) for the experimental data for the cluster-size dependence of the CE energetics and for its dependence on the laser pulse parameters, as well as for the anisotropy in the angular distribution of the energies of the Xe(q+) ions. Possible applications of this computational study include a control of the ion kinetic energies by the choice of the laser intensity profile (2D∕3D) in the laser-cluster interaction volume.
A simplified model for average kinetic energy flux within large wind turbine arrays
NASA Astrophysics Data System (ADS)
Markfort, Corey; Zhang, Wei; Porte-Agel, Fernando
2015-11-01
We investigate the kinetic energy distribution within an array of wind turbines using a 1-D model for the interactions between large-scale wind farms and the atmospheric boundary layer (ABL). Obstructed shear flow scaling is used to predict the development length of the wind farm flow as well as vertical momentum flux. Within the region of flow development, momentum and energy is advected into the wind farm and wake turbulence draws excess momentum in from between turbines. This is characterized by large dispersive fluxes. Once the flow within the farm is developed, the area - averaged velocity profile exhibits an inflection point, characteristic of obstructed shear flows. The inflected velocity profile is responsible for a characteristic turbulence eddy scale, which may be responsible for a significant amount of the vertical momentum and energy flux. Prediction of this scale is useful for determining the amount of available power for harvesting. The model result for kinetic energy flux is compared to wind tunnel measurements. The model is useful for optimizing wind turbine spacing and layout, and for assessing the impacts of wind farms on nearby wind resources and the environment.
Kinetic Energy Recovery from the Chimney Flue Gases Using Ducted Turbine System
NASA Astrophysics Data System (ADS)
Mann, Harjeet S.; Singh, Pradeep K.
2017-03-01
An innovative idea of extracting kinetic energy from man-made wind resources using ducted turbine system for on-site power generation is introduced in this paper. A horizontal axis ducted turbine is attached to the top of the chimney to harness the kinetic energy of flue gases for producing electricity. The turbine system is positioned beyond the chimney outlet, to avoid any negative impact on the chimney performance. The convergent-divergent duct causes increase in the flue gas velocity and hence enhances the performance of the turbine. It also acts as a safety cover to the energy recovery system. The results from the CFD based simulation analysis indicate that significant power 34 kW can be harnessed from the chimney exhaust. The effect of airfoils NACA4412 and NACA4416 and the diffuser angle on the power extraction by the energy recovery system using a 6-bladed ducted turbine has been studied with the CFD simulation. It is observed that the average flue gas velocity in the duct section at the throat is approximately twice that of the inlet velocity, whereas maximum velocity achieved is 2.6 times the inlet velocity. The simulated results show that about power may be extracted from the chimney flue gases of 660 MW power plant. The system can be retrofitted to existing chimneys of thermal power plants, refineries and other industries.
Turbulence power and kinetic energy spectra measured by a temporal-to-spatial record conversion
NASA Astrophysics Data System (ADS)
Buchhave, Preben; Velte, Clara
2015-11-01
A method of converting a time record of turbulent velocity measured at a point in a flow to a spatial velocity record consisting of consecutive streak line elements that allows computation of turbulent kinetic wavenumber spectra is briefly introduced (more detail in a related paper at this conference, see ref). The method completely bypasses the problems with Taylor's hypothesis caused by fluctuating convection velocities. In the present contribution, we discuss the interpretation of the first order static moments (e.g. mean and rms velocity) and second order dynamic moments (e.g. spatial correlation function and energy spectrum) computed from the spatial record, which was derived from the measured temporal record. We compare several possible versions of the new energy spectra with the classical 1D and 3D energy spectra and the so-called total kinetic energy spectrum and discuss the range of validity of any equivalence between the new computations and the classical ones. Ref.: Clara M. Velte: A novel time-to-space conversion methods bypassing the problems with Taylor's hypothesis caused by fluctuating convection velocities
Comparison of CME masses and kinetic energies near the Sun and in the inner heliosphere
NASA Technical Reports Server (NTRS)
Webb, D. F.; Howard, R. A.; Jackson, B. V.
1995-01-01
Masses have now been determined for many of the CMEs observed in the inner heliosphere by the HELIOS 1 and 2 zodiacal light photometers. The speed of the brightest material of each CME has also been measured so that, for events having both mass and speed determinations, the kinetic energies of the CMEs are estimated. We compare the masses and kinetic energies of the individual CMEs measured in the inner heliosphere by HELIOS and near the Sun from observations by the SOLWIND (1979-1983) and SMM coronagraphs (1980). Where feasible we also compare the speeds of the same CMEs. We find that the HELIOS masses and energies tend to be somewhat larger by factors of 2-5 than those derived from the coronagraph data. We also compare the distribution of the masses and energies of the HELIOS and coronagraph CMEs over the solar cycle. These results provide an important baseline for observations of CMEs from coronagraphs, from the ISEE-3/ICE, WIND and Ulysses spacecraft and in the future from SOHO.
Enhanced von Weizsäcker Wang-Govind-Carter kinetic energy density functional for semiconductors
NASA Astrophysics Data System (ADS)
Shin, Ilgyou; Carter, Emily A.
2014-05-01
We propose a new form of orbital-free (OF) kinetic energy density functional (KEDF) for semiconductors that is based on the Wang-Govind-Carter (WGC99) nonlocal KEDF. We enhance within the latter the semi-local von Weizsäcker KEDF term, which is exact for a single orbital. The enhancement factor we introduce is related to the extent to which the electron density is localized. The accuracy of the new KEDF is benchmarked against Kohn-Sham density functional theory (KSDFT) by comparing predicted energy differences between phases, equilibrium volumes, and bulk moduli for various semiconductors, along with metal-insulator phase transition pressures. We also compare point defect and (100) surface energies in silicon for a broad test of its applicability. This new KEDF accurately reproduces the exact non-interacting kinetic energy of KSDFT with only one additional adjustable parameter beyond the three parameters in the WGC99 KEDF; it exhibits good transferability between semiconducting to metallic silicon phases and between various III-V semiconductors without parameter adjustment. Overall, this KEDF is more accurate than previously proposed OF KEDFs (e.g., the Huang-Carter (HC) KEDF) for semiconductors, while the computational efficiency remains at the level of the WGC99 KEDF (several hundred times faster than the HC KEDF). This accurate, fast, and transferable new KEDF holds considerable promise for large-scale OFDFT simulations of metallic through semiconducting materials.
Enhanced von Weizsäcker Wang-Govind-Carter kinetic energy density functional for semiconductors.
Shin, Ilgyou; Carter, Emily A
2014-05-14
We propose a new form of orbital-free (OF) kinetic energy density functional (KEDF) for semiconductors that is based on the Wang-Govind-Carter (WGC99) nonlocal KEDF. We enhance within the latter the semi-local von Weizsäcker KEDF term, which is exact for a single orbital. The enhancement factor we introduce is related to the extent to which the electron density is localized. The accuracy of the new KEDF is benchmarked against Kohn-Sham density functional theory (KSDFT) by comparing predicted energy differences between phases, equilibrium volumes, and bulk moduli for various semiconductors, along with metal-insulator phase transition pressures. We also compare point defect and (100) surface energies in silicon for a broad test of its applicability. This new KEDF accurately reproduces the exact non-interacting kinetic energy of KSDFT with only one additional adjustable parameter beyond the three parameters in the WGC99 KEDF; it exhibits good transferability between semiconducting to metallic silicon phases and between various III-V semiconductors without parameter adjustment. Overall, this KEDF is more accurate than previously proposed OF KEDFs (e.g., the Huang-Carter (HC) KEDF) for semiconductors, while the computational efficiency remains at the level of the WGC99 KEDF (several hundred times faster than the HC KEDF). This accurate, fast, and transferable new KEDF holds considerable promise for large-scale OFDFT simulations of metallic through semiconducting materials.
Kinetic Energy Recovery from the Chimney Flue Gases Using Ducted Turbine System
NASA Astrophysics Data System (ADS)
Mann, Harjeet S.; Singh, Pradeep K.
2017-03-01
An innovative idea of extracting kinetic energy from man-made wind resources using ducted turbine system for on-site power generation is introduced in this paper. A horizontal axis ducted turbine is attached to the top of the chimney to harness the kinetic energy of flue gases for producing electricity. The turbine system is positioned beyond the chimney outlet, to avoid any negative impact on the chimney performance. The convergent-divergent duct causes increase in the flue gas velocity and hence enhances the performance of the turbine. It also acts as a safety cover to the energy recovery system. The results from the CFD based simulation analysis indicate that significant power 34 kW can be harnessed from the chimney exhaust. The effect of airfoils NACA4412 and NACA4416 and the diffuser angle on the power extraction by the energy recovery system using a 6-bladed ducted turbine has been studied with the CFD simulation. It is observed that the average flue gas velocity in the duct section at the throat is approximately twice that of the inlet velocity, whereas maximum velocity achieved is 2.6 times the inlet velocity. The simulated results show that about power may be extracted from the chimney flue gases of 660 MW power plant. The system can be retrofitted to existing chimneys of thermal power plants, refineries and other industries.
Kinetic study of solid waste pyrolysis using distributed activation energy model.
Bhavanam, Anjireddy; Sastry, R C
2015-02-01
The pyrolysis characteristics of municipal solid waste, agricultural residues such as ground nut shell, cotton husk and their blends are investigated using non-isothermal thermogravimetric analysis (TGA) with in a temperature range of 30-900 °C at different heating rates of 10 °C, 30 °C and 50 °C/min in inert atmosphere. From the thermograms obtained from TGA, it is observed that the maximum rate of degradation occurred in the second stage of the pyrolysis process for all the solid wastes. The distributed activation energy model (DAEM) is used to study the pyrolysis kinetics of the solid wastes. The kinetic parameters E (activation energy), k0 (frequency factor) are calculated from this model. It is found that the range of activation energies for agricultural residues are lower than the municipal solid waste. The activation energies for the municipal solid waste pyrolysis process drastically decreased with addition of agricultural residues. The proposed DAEM is successfully validated with TGA experimental data.
Electron kinetic energy and plasma emission diagnosis from femtosecond laser produced air plasmas
NASA Astrophysics Data System (ADS)
Heins, A.; Singh, S. C.; Guo, C.
2017-07-01
The characteristics of a plasma formed by a focused ultrashort laser in atmospheric-pressure air are studied with linear and circular pulses. We show that the ionization threshold for circular pulses is 1.36 times higher than for that linear pulses. Using an intensified CCD camera, we study plasma emission over seven orders of magnitude in a dynamic range. In spite of possessing a lower total ion number, plasmas produced by circular pulses are found to be brighter visible-light emitters than those produced by linear pulses of the same energy. This indicates that circular pulses produce plasmas with more electron kinetic energy than linear pulses and that kinetic energy plays a role in the optical emission intensity. The presence of high energy electrons is verified by demonstrating that a high-ionization-potential gas can be made to radiate more brightly by the addition of a low-ionization-potential gas even though the second gas lowers the achievable focal intensity.
Aggregation of liposomes induced by calcium: A structural and kinetic study
NASA Astrophysics Data System (ADS)
Roldán-Vargas, Sándalo; Martín-Molina, Alberto; Quesada-Pérez, Manuel; Barnadas-Rodríguez, Ramon; Estelrich, Joan; Callejas-Fernández, José
2007-02-01
In this work, the calcium-induced aggregation of phosphatidylserine liposomes is probed by means of the analysis of the kinetics of such process as well as the aggregate morphology. This novel characterization of liposome aggregation involves the use of static and dynamic light-scattering techniques to obtain kinetic exponents and fractal dimensions. For salt concentrations larger than 5mM , a diffusion-limited aggregation regime is observed and the Brownian kernel properly describes the time evolution of the diffusion coefficient. For slow kinetics, a slightly modified multiple contact kernel is required. In any case, a time evolution model based on the numerical resolution of Smoluchowski’s equation is proposed in order to establish a theoretical description for the aggregating system. Such a model provides an alternative procedure to determine the dimerization constant, which might supply valuable information about interaction mechanisms between phospholipid vesicles.
Pak, Alireza; Lesage, Denis; Gimbert, Yves; Vékey, Károly; Tabet, Jean-Claude
2008-04-01
The internal energy of ions and the timescale play fundamental roles in mass spectrometry. The main objective of this study is to estimate and compare the internal energy distributions of different ions (different nature, degree of freedom 'DOF' and fragmentations) produced in an electrospray source (ESI) of a triple-quadrupole instrument (Quattro I Micromass). These measurements were performed using both the Survival Yield method (as proposed by De Pauw) and the MassKinetics software (kinetic model introduced by Vékey). The internal energy calibration is the preliminary step for ESI and collision-induced dissociation (CID) spectra calculation. meta-Methyl-benzylpyridinium ion and four protonated peptides (YGGFL, LDIFSDF, LDIFSDFR and RLDIFSDF) were produced using an electrospray source. These ions were used as thermometer probe compounds. Cone voltages (V(c)) were linearly correlated with the mean internal energy values (
Kinetic Modeling of Slow Energy Release in Non-Ideal Carbon Rich Explosives
Vitello, P; Fried, L; Glaesemann, K; Souers, C
2006-06-20
We present here the first self-consistent kinetic based model for long time-scale energy release in detonation waves in the non-ideal explosive LX-17. Non-ideal, insensitive carbon rich explosives, such as those based on TATB, are believed to have significant late-time slow release in energy. One proposed source of this energy is diffusion-limited growth of carbon clusters. In this paper we consider the late-time energy release problem in detonation waves using the thermochemical code CHEETAH linked to a multidimensional ALE hydrodynamics model. The linked CHEETAH-ALE model dimensional treats slowly reacting chemical species using kinetic rate laws, with chemical equilibrium assumed for species coupled via fast time-scale reactions. In the model presented here we include separate rate equations for the transformation of the un-reacted explosive to product gases and for the growth of a small particulate form of condensed graphite to a large particulate form. The small particulate graphite is assumed to be in chemical equilibrium with the gaseous species allowing for coupling between the instantaneous thermodynamic state and the production of graphite clusters. For the explosive burn rate a pressure dependent rate law was used. Low pressure freezing of the gas species mass fractions was also included to account for regions where the kinetic coupling rates become longer than the hydrodynamic time-scales. The model rate parameters were calibrated using cylinder and rate-stick experimental data. Excellent long time agreement and size effect results were achieved.
Statistical properties of kinetic and total energy densities in reverberant spaces.
Jacobsen, Finn; Molares, Alfonso Rodríguez
2010-04-01
Many acoustical measurements, e.g., measurement of sound power and transmission loss, rely on determining the total sound energy in a reverberation room. The total energy is usually approximated by measuring the mean-square pressure (i.e., the potential energy density) at a number of discrete positions. The idea of measuring the total energy density instead of the potential energy density on the assumption that the former quantity varies less with position than the latter goes back to the 1930s. However, the phenomenon was not analyzed until the late 1970s and then only for the region of high modal overlap, and this analysis has never been published. Moreover, until fairly recently, measurement of the total sound energy density required an elaborate experimental arrangement based on finite-difference approximations using at least four amplitude and phase matched pressure microphones. With the advent of a three-dimensional particle velocity transducer, it has become somewhat easier to measure total rather than only potential energy density in a sound field. This paper examines the ensemble statistics of kinetic and total sound energy densities in reverberant enclosures theoretically, experimentally, and numerically.
Karimi, Alireza; Navidbakhsh, Mahdi; Razaghi, Reza
2014-06-01
Polyvinyl alcohol (PVA) sponge is in widespread use for biomedical and tissue engineering applications owing to its biocompatibility, availability, relative cheapness, and excellent mechanical properties. This study reports a novel concept of design in energy absorbing materials which consist in the use of PVA sponge as an alternative reinforcement material to enhance the energy loss of impact loads. An experimental study is carried out to measure the mechanical properties of the PVA sponge under uniaxial loading. The kinetic energy absorption capacity of the PVA sponge is computed by a hexahedral finite element (FE) model of the steel ball and bullet through the LS-DYNA code under impact load at three different thicknesses (5, 10, 15mm). The results show that a higher sponge thickness invokes a higher energy loss of the steel ball and bullet. The highest energy loss of the steel ball and bullet is observed for the thickest sponge with 160 and 35J, respectively. The most common type of traumatic brain injury in which the head subject to impact load causes the brain to move within the skull and consequently brain hemorrhaging. These results suggest the application of the PVA sponge as a great kinetic energy absorber material compared to commonly used expanded polystyrene foams (EPS) to absorb most of the impact energy and reduces the transmitted load. The results might have implications not only for understanding of the mechanical properties of PVA sponge but also for use as an alternative reinforcement material in helmet and packaging material design. Copyright © 2014 Elsevier B.V. All rights reserved.
NASA Astrophysics Data System (ADS)
Fujii, Mikiya; Takatsuka, Kazuo
2007-11-01
The temperature and heat capacity of isolated atomic clusters are studied in terms of an ab initio statistical theory of kinetic energy distribution by atomic evaporation. Two definitions of canonical temperature are examined and numerically compared: One is based on the most probable kinetic energy release (KER), whereas the other is determined with use of the entire distribution of the KER. The mutual relationship and their advantages are discussed.
Liu, Qi; Gao, Min-Rui; Liu, Yuzi; Okasinski, John S; Ren, Yang; Sun, Yugang
2016-01-13
The fast reaction kinetics presented in the microwave synthesis of colloidal silver nanoparticles was quantitatively studied, for the first time, by integrating a microwave reactor with in situ X-ray diffraction at a high-energy synchrotron beamline. Comprehensive data analysis reveals two different types of reaction kinetics corresponding to the nucleation and growth of the Ag nanoparticles. The formation of seeds (nucleation) follows typical first-order reaction kinetics with activation energy of 20.34 kJ/mol, while the growth of seeds (growth) follows typical self-catalytic reaction kinetics. Varying the synthesis conditions indicates that the microwave colloidal chemistry is independent of concentration of surfactant. These discoveries reveal that the microwave synthesis of Ag nanoparticles proceeds with reaction kinetics significantly different from the synthesis present in conventional oil bath heating. The in situ X-ray diffraction technique reported in this work is promising to enable further understanding of crystalline nanomaterials formed through microwave synthesis.
Dynamic Positron Emission Tomography Image Restoration via a Kinetics-Induced Bilateral Filter
Bian, Zhaoying; Huang, Jing; Ma, Jianhua; Lu, Lijun; Niu, Shanzhou; Zeng, Dong; Feng, Qianjin; Chen, Wufan
2014-01-01
Dynamic positron emission tomography (PET) imaging is a powerful tool that provides useful quantitative information on physiological and biochemical processes. However, low signal-to-noise ratio in short dynamic frames makes accurate kinetic parameter estimation from noisy voxel-wise time activity curves (TAC) a challenging task. To address this problem, several spatial filters have been investigated to reduce the noise of each frame with noticeable gains. These filters include the Gaussian filter, bilateral filter, and wavelet-based filter. These filters usually consider only the local properties of each frame without exploring potential kinetic information from entire frames. Thus, in this work, to improve PET parametric imaging accuracy, we present a kinetics-induced bilateral filter (KIBF) to reduce the noise of dynamic image frames by incorporating the similarity between the voxel-wise TACs using the framework of bilateral filter. The aim of the proposed KIBF algorithm is to reduce the noise in homogeneous areas while preserving the distinct kinetics of regions of interest. Experimental results on digital brain phantom and in vivo rat study with typical 18F-FDG kinetics have shown that the present KIBF algorithm can achieve notable gains over other existing algorithms in terms of quantitative accuracy measures and visual inspection. PMID:24586657
Garcia-Aldea, David; Alvarellos, J. E.
2007-11-15
We study two families of approximate nonlocal kinetic-energy functionals that include a full von Weizsaecker functional, and that have nonlocal terms with the mathematical structure of the Thomas-Fermi functional. The functionals recover the exact kinetic energy and the linear response function of a homogeneous electron system. The first family is a generalization of a successful previous nonlocal functional. The second family is proposed in the paper, and is designed to obtain functionals suitable for use in both localized and extended systems. Furthermore, this family has been designed to be evaluated by a single integration in momentum space when a constant reference density is used. The atomic total kinetic energies are in good agreement with the exact calculations. The kinetic-energy density corresponding to each functional has been assessed to control its quality. The results show that, in general, these functionals behave better than both the Thomas-Fermi and all semilocal generalized gradient approximation functionals when describing the kinetic-energy density of atoms, providing a better description of the nonlocal effects of the kinetic energy of electron systems.
NASA Astrophysics Data System (ADS)
Towers, J.; van Zyl, B. P.; Kirkby, W.
2015-08-01
In a recent paper [B. P. van Zyl et al., Phys. Rev. A 89, 022503 (2014), 10.1103/PhysRevA.89.022503], the average density approximation (ADA) was implemented to develop a parameter-free, nonlocal kinetic energy functional to be used in the orbital-free density functional theory of an inhomogeneous, two-dimensional (2D) Fermi gas. In this work, we provide a detailed comparison of self-consistent calculations within the ADA with the exact results of the Kohn-Sham density functional theory and the elementary Thomas-Fermi (TF) approximation. We demonstrate that the ADA for the 2D kinetic energy functional works very well under a wide variety of confinement potentials, even for relatively small particle numbers. Remarkably, the TF approximation for the kinetic energy functional, without any gradient corrections, also yields good agreement with the exact kinetic energy for all confining potentials considered, although at the expense of the spatial and kinetic energy densities exhibiting poor pointwise agreement, particularly near the TF radius. Our findings illustrate that the ADA kinetic energy functional yields accurate results for both the local and global equilibrium properties of an inhomogeneous 2D Fermi gas, without the need for any fitting parameters.
Noise induced transitions in rugged energy landscapes
NASA Astrophysics Data System (ADS)
Pradas, Marc; Duncan, Andrew; Kalliadasis, Serafim; Pavliotis, Greg
2016-11-01
External or internal random fluctuations are ubiquitous in many physical and technological systems and can play a key role in their dynamics often inducing a wide variety of complex spatiotemporal phenomena, including noise-induced spatial patterns and noise-induced phase transitions. Many of these phenomena can be modelled by noisy multiscale systems characterized by the presence of a wide range of different time- and lengthscales interacting nontrivially with each other. Here we analyse the effects of additive noise on systems that are described in terms of a rugged energy landscape, modelled as a slowly-varying multiscale potential perturbed by periodic multiscale fluctuations. Some examples of this problem include the dynamics of sessile droplets on heterogeneous substrates, crystallization and the evolution of protein folding. We demonstrate that the interplay between noise and the small scale fluctuations in the potential can give rise to a dramatically different bifurcation structure and dynamical behaviour compared to that of the original, unperturbed model. For instance, we observe several nontrivial and largely unexpected dynamic-state transitions controlled by the noise intensity. We characterize these transitions in terms of critical exponents.
Potential to kinetic energy conversion in wave number domain for the Southern Hemisphere
NASA Technical Reports Server (NTRS)
Huang, H.-J.; Vincent, D. G.
1984-01-01
Preliminary results of a wave number study conducted for the South Pacific Convergence Zone (SPCZ) using FGGE data for the period January 10-27, 1979 are reported. In particular, three variables (geomagnetic height, z, vertical p-velocity, omega, and temperature, T) and one energy conversion quantity, omega-alpha (where alpha is the specific volume), are shown. It is demonstrated that wave number 4 plays an important role in the conversion from available potential energy to kinetic energy in the Southern Hemisphere tropics, particularly in the vicinity of the SPCZ. It is therefore suggested that the development and movement of wave number 4 waves be carefully monitored in making forecasts for the South Pacific region.
Sensory Agreement Guides Kinetic Energy Optimization of Arm Movements during Object Manipulation.
Farshchiansadegh, Ali; Melendez-Calderon, Alejandro; Ranganathan, Rajiv; Murphey, Todd D; Mussa-Ivaldi, Ferdinando A
2016-04-01
The laws of physics establish the energetic efficiency of our movements. In some cases, like locomotion, the mechanics of the body dominate in determining the energetically optimal course of action. In other tasks, such as manipulation, energetic costs depend critically upon the variable properties of objects in the environment. Can the brain identify and follow energy-optimal motions when these motions require moving along unfamiliar trajectories? What feedback information is required for such optimal behavior to occur? To answer these questions, we asked participants to move their dominant hand between different positions while holding a virtual mechanical system with complex dynamics (a planar double pendulum). In this task, trajectories of minimum kinetic energy were along curvilinear paths. Our findings demonstrate that participants were capable of finding the energy-optimal paths, but only when provided with veridical visual and haptic information pertaining to the object, lacking which the trajectories were executed along rectilinear paths.
The analysis and kinetic energy balance of an upper-level wind maximum during intense convection
NASA Technical Reports Server (NTRS)
Fuelberg, H. E.; Jedlovec, G. J.
1982-01-01
The purpose of this paper is to analyze the formation and maintenance of the upper-level wind maximum which formed between 1800 and 2100 GMT, April 10, 1979, during the AVE-SESAME I period, when intense storms and tornadoes were experienced (the Red River Valley tornado outbreak). Radiosonde stations participating in AVE-SESAME I are plotted (centered on Oklahoma). National Meteorological Center radar summaries near the times of maximum convective activity are mapped, and height and isotach plots are given, where the formation of an upper-level wind maximum over Oklahoma is the most significant feature at 300 mb. The energy balance of the storm region is seen to change dramatically as the wind maximum forms. During much of its lifetime, the upper-level wind maximum is maintained by ageostrophic flow that produces cross-contour generation of kinetic energy and by the upward transport of midtropospheric energy. Two possible mechanisms for the ageostrophic flow are considered.
The distribution of eddy kinetic and potential energies in the global ocean
NASA Astrophysics Data System (ADS)
Ferrari, Raffaele; Wunsch, Carl
2010-03-01
Understanding of the major sources, sinks, and reservoirs of energy in the ocean is briefly updated in a diagram. The nature of the dominant kinetic energy reservoir, that of the balanced variablity, is then found to be indistinguishable in the observations from a sum of barotropic and first baroclinic ordinary quasi-geostrophic modes. Little supporting evidence is available to partition the spectra among forced motions and turbulent cascades, along with significant energy more consistent with weakly non-linear wave dynamics. Linear-response wind-forced motions appear to dominate the high frequency (but subinertial) mooring frequency spectra. Turbulent cascades appear to fill the high wavenumber spectra in altimetric data and numerical simulations. Progress on these issues is hindered by the difficulty in connecting the comparatively easily available frequency spectra with the variety of theoretically predicted wavenumber spectra.
NASA Astrophysics Data System (ADS)
Wen, Tong; Zhao, Yunliang; Xiao, Qihang; Ma, Qiulin; Kang, Shichang; Li, Hongqiang; Song, Shaoxian
The microwave-assisted leaching was a new approach to intensify the copper recovery from chalcopyrite by hydrometallurgy. In this work, the effect of microwave-assisted heating on chalcopyrite leaching of kinetics, interfacial reaction temperature and surface energy were investigated. The activation energy of chalcopyrite leaching was affected indistinctively by the microwave-assisted heating (39.1 kJ/mol) compared with the conventional heating (43.9 kJ/mol). However, the boiling point of the leaching system increased through microwave-assisted heating. Because of the improved boiling point and the selective heating of microwave, the interfacial reaction temperature increased significantly, which gave rise to the increase of the leaching recovery of copper. Moreover, the surface energy of the chalcopyrite through microwave-assisted heating was also enhanced, which was beneficial to strengthen the leaching of chalcopyrite.
Potential to kinetic energy conversion in wave number domain for the Southern Hemisphere
NASA Technical Reports Server (NTRS)
Huang, H.-J.; Vincent, D. G.
1984-01-01
Preliminary results of a wave number study conducted for the South Pacific Convergence Zone (SPCZ) using FGGE data for the period January 10-27, 1979 are reported. In particular, three variables (geomagnetic height, z, vertical p-velocity, omega, and temperature, T) and one energy conversion quantity, omega-alpha (where alpha is the specific volume), are shown. It is demonstrated that wave number 4 plays an important role in the conversion from available potential energy to kinetic energy in the Southern Hemisphere tropics, particularly in the vicinity of the SPCZ. It is therefore suggested that the development and movement of wave number 4 waves be carefully monitored in making forecasts for the South Pacific region.
Inversion Vibrational Energy Levels of AsH3 + Studied by Zero-Kinetic Photoelectron Spectroscopy
NASA Astrophysics Data System (ADS)
Mo, Yuxiang
2016-06-01
The rotational-resolved vibrational spectra of AsH3 + have been measured for the first time with vibrational energies up to 6000 wn above the ground state using zero-kinetic energy photoelectron spectroscopic method. The inversion vibrational energy levels (νb{2}) and the corresponding rotational constants for the νb{2} =0-16 have been determined. The tunneling splittings of the inversion vibration energy levels have been observed for the ground and the first excited vibrational states. The geometric parameters of AsH3 + as a function of inversion vibrational quantum states have been determined, indicating that the geometric structure of the cation changes from near planar structure to a pyramidal structure with more vibrational excitations. In addition to the experimental measurement, a two-dimensional theoretical calculation including the two symmetric vibrational modes was performed to determine the energy levels of the symmetric inversion and As-H stretching vibrations. The calculated vibrational energy levels are in good agreement with the experimental results. The first adiabatic ionization energy (IE) for AsH3 was also accurately determined. The result of this work will be compared with our published result on the PH3+.
Electromagnetic energy conversion in downstream fronts from three dimensional kinetic reconnection
Lapenta, Giovanni; Goldman, Martin; Newman, David; Markidis, Stefano; Divin, Andrey
2014-05-15
The electromagnetic energy equation is analyzed term by term in a 3D simulation of kinetic reconnection previously reported by Vapirev et al. [J. Geophys. Res.: Space Phys. 118, 1435 (2013)]. The evolution presents the usual 2D-like topological structures caused by an initial perturbation independent of the third dimension. However, downstream of the reconnection site, where the jetting plasma encounters the yet unperturbed pre-existing plasma, a downstream front is formed and made unstable by the strong density gradient and the unfavorable local acceleration field. The energy exchange between plasma and fields is most intense at the instability, reaching several pW/m{sup 3}, alternating between load (energy going from fields to particles) and generator (energy going from particles to fields) regions. Energy exchange is instead purely that of a load at the reconnection site itself in a region focused around the x-line and elongated along the separatrix surfaces. Poynting fluxes are generated at all energy exchange regions and travel away from the reconnection site transporting an energy signal of the order of about S≈10{sup −3}W/m{sup 2}.
Goel, N K; Kumar, Virendra; Pahan, S; Bhardwaj, Y K; Sabharwal, S
2011-10-15
Mutual radiation grafting technique was employed to graft polyacrylic acid (PAA) onto Polytetrafluoroethylene (Teflon) scrap using high energy gamma radiation. Polyacrylic acid-g-Teflon (PAA-g-Teflon) adsorbent was characterized by grafting extent measurement, FTIR spectroscopy, SEM and wet ability & surface energy analysis. The PAA-g-Teflon adsorbent was studied for dye adsorption from aqueous solution of basic dyes, namely, Basic red 29 (BR29) and Basic yellow 11 (BY11). The equilibrium adsorption data were analyzed by Langmuir and Freundlich adsorption isotherm models, whereas, adsorption kinetics was analyzed using pseudo-first order, pseudo-second order and intra-particle diffusion kinetic models. Equilibrium adsorption of BR29 was better explained by Langmuir adsorption model, while that of BY11 by Freundlich adsorption model. The adsorption capacity for BY11 was more than for BR29. Separation factor (R(L)) was found to be in the range 0 < R(L) < 1, indicating favorable adsorption of dyes. Higher coefficient of determination (r(2) > 0.99) and better agreement between the q(e,cal) and q(e,exp) values suggested that pseudo-second order kinetic model better represents the kinetic adsorption data. The non-linearity obtained for intra-particle diffusion plot indicated, more than one process is involved in the adsorption of basic dyes. The desorption studies showed that ~95% of the adsorbed dye could be eluted in suitable eluent.
Vázquez, Juana; Harding, Michael E; Stanton, John F; Gauss, Jürgen
2011-05-10
A variational method for the calculation of low-lying vibrational energy levels of molecules with small amplitude vibrations is presented. The approach is based on the Watson Hamiltonian in rectilinear normal coordinates and characterized by a quasi-analytic integration over the kinetic energy operator (KEO). The KEO beyond the harmonic approximation is represented by a Taylor series in terms of the rectilinear normal coordinates around the equilibrium configuration. This formulation of the KEO enables its extension to arbitrary order until numerical convergence is reached for those states describing small amplitude motions and suitably represented with a rectilinear system of coordinates. A Gauss-Hermite quadrature grid representation of the anharmonic potential is used for all the benchmark examples presented. Results for a set of molecules with linear and nonlinear configurations, i.e., CO2, H2O, and formyl fluoride (HFCO), illustrate the performance of the method and the versatility of our implementation.
Microwave treatment of dairy manure for resource recovery: Reaction kinetics and energy analysis.
Srinivasan, Asha; Liao, Ping H; Lo, Kwang V
2016-12-01
A newly designed continuous-flow 915 MHz microwave wastewater treatment system was used to demonstrate the effectiveness of the microwave enhanced advanced oxidation process (MW/H2O2-AOP) for treating dairy manure. After the treatment, about 84% of total phosphorus and 45% of total chemical oxygen demand were solubilized with the highest H2O2 dosage (0.4% H2O2 per %TS). The reaction kinetics of soluble chemical oxygen demand revealed activation energy to be in the range of 5-22 kJ mole(-1). The energy required by the processes was approximately 0.16 kWh per liter of dairy manure heated. A higher H2O2 dosage used in the system had a better process performance in terms of solids solubilization, reaction kinetics, and energy consumption. Cost-benefit analysis for a farm-scale MW/H2O2-AOP treatment system was also presented. The results obtained from this study would provide the basic knowledge for designing an effective farm-scale dairy manure treatment system.
Random activation energy model and disordered kinetics, from static to dynamic disorder.
Vlad, Marcel Ovidiu; Cerofolini, Gianfranco; Oefner, Peter; Ross, John
2005-11-17
We suggest a unified path integral approach for random rate processes with random energy barriers, which includes systems with static and dynamic disorder as particular cases. We assume that the random component of the activation energy barrier can be described by a generalized Zubarev-McLennan nonequilibrum statistical ensemble that can be derived from the maximum information entropy approach by assuming that the time history of the fluctuations of the random components of the energy barrier are known. We show that the average survival function, which is an experimental observable in disorderd kinetics, can be computed exactly in terms of the characteristic functional of this generalized Zubarev-McLennan nonequilibrium statistical ensemble. We investigate different types of disorder described by our approach, ranging from static disorder with infinite memory to random processes with long or short memory, and finally to rapidly fluctuating independent random processes with no memory. We derive expressions of the average survival function for all these types of disorder and discuss their implications in the evaluation of kinetic parameters from experimental data. We illustrate our approach by studying a simple model of dynamic disorder of the renewal type. Finally we discuss briefly the implications of our approach in molecular biology and genetics.
Lee, H.; Wu, C.-Y.; Yang, S.K.; Lee, Y.-P.
2005-08-15
Following photodissociation of formyl fluoride (HFCO) at 193 nm, we detected products with fragmentation translational spectroscopy utilizing a tunable vacuum ultraviolet beam from a synchrotron for ionization. Among three primary dissociation channels observed in this work, the F-elimination channel HFCO{yields}HCO+F dominates, with a branching ratio {approx}0.66 and an average release of kinetic energy {approx}55 kJ mol{sup -1}; about 17% of HCO further decomposes to H+CO. The H-elimination channel HFCO{yields}FCO+H has a branching ratio {approx}0.28 and an average release of kinetic energy {approx}99 kJ mol{sup -1}; about 21% of FCO further decomposes to F+CO. The F-elimination channel likely proceeds via the S{sub 1} surface whereas the H-elimination channel proceeds via the T{sub 1} surface; both channels exhibit moderate barriers for dissociation. The molecular HF-elimination channel HFCO{yields}HF+CO, correlating with the ground electronic surface, has a branching ratio of only {approx}0.06; the average translational release of 93 kJ mol{sup -1}, {approx}15% of available energy, implies that the fragments are highly internally excited. Detailed mechanisms of photodissociation are discussed.
Ardoña, Herdeline Ann M; Draper, Emily R; Citossi, Francesca; Wallace, Matthew; Serpell, Louise C; Adams, Dave J; Tovar, John D
2017-06-28
We report a peptide-based multichromophoric hydrogelator system, wherein π-electron units with different inherent spectral energies are spatially controlled within peptidic 1-D nanostructures to create localized energy gradients in aqueous environments. This is accomplished by mixing different π-conjugated peptides prior to initiating self-assembly through solution acidification. We can vary the kinetics of the assembly and the degree of self-sorting through the choice of the assembly trigger, which changes the kinetics of acidification. The hydrolysis of glucono-δ-lactone (GdL) provides a slow pH drop that allows for stepwise triggering of peptide components into essentially self-sorted nanostructures based on subtle pKa differences, whereas HCl addition leads to a rapid formation of mixed components within a nanostructure. Using (1)H NMR spectroscopy and fiber X-ray diffraction, we determine the conditions and peptide mixtures that favor self-sorting or intimate comixing. Photophysical investigations in the solution phase provide insight into the correlation of energy-transport processes occurring within the assemblies to the structural organization of the π-systems.
Asymptotic domination of cold relativistic MHD winds by kinetic energy flux
NASA Technical Reports Server (NTRS)
Begelman, Mitchell C.; Li, Zhi-Yun
1994-01-01
We study the conditions which lead to the conversion of most Poynting flux into kinetic energy flux in cold, relativistic hydromagnetic winds. It is shown that plasma acceleration along a precisely radial flow is extremely inefficient due to the near cancellation of the toroidal magnetic pressure and tension forces. However, if the flux tubes in a flow diverge even slightly faster than radially, the fast magnetosonic point moves inward from infinity to a few times the light cylinder radius. Once the flow becomes supermagnetosonic, further divergence of the flux tubes beyond the fast point can accelerate the flow via the 'magnetic nozzle' effect, thereby further converting Poynting flux to kinetic energy flux. We show that the Grad-Shafranov equation admits a generic family of kinetic energy-dominated asymptotic wind solutions with finite total magnetic flux. The Poynting flux in these solutions vanishes logarithmically with distance. The way in which the flux surfaces are nested within the flow depends only on the ratio of angular velocity to poliodal 4-velocity as a function of magnetic flux. Radial variations in flow structure can be expressed in terms of a pressure boundary condition on the outermost flux surface, provided that no external toriodal field surrounds the flow. For a special case, we show explicitly how the flux surfaces merge gradually to their asymptotes. For flows confined by an external medium of pressure decreasing to zero at infinity we show that, depending on how fast the ambient pressure declines, the final flow state could be either a collimated jet or a wind that fills the entire space. We discuss the astrophysical implications of our results for jets from active galactic nuclei and for free pulsar winds such as that believed to power the Crab Nebula.
Numerical and experimental assessment of turbulent kinetic energy in an aortic coarctation.
Lantz, Jonas; Ebbers, Tino; Engvall, Jan; Karlsson, Matts
2013-07-26
The turbulent blood flow through an aortic coarctation in a 63-year old female patient was studied experimentally using magnetic resonance imaging (MRI), and numerically using computational fluid dynamics (CFD), before and after catheter intervention. Turbulent kinetic energy (TKE) was computed in the numerical model using large eddy simulation and compared with direct in vivo MRI measurements. Despite the two totally different methods to obtain TKE values, both quantitative and qualitative results agreed very well. The results showed that even though both blood flow rate and Reynolds number increased after intervention, total turbulent kinetic energy levels decreased in the coarctation. Therefore, the use of the Reynolds number alone as a measure of turbulence in cardiovascular flows should be used with caution. Furthermore, the change in flow field and kinetic energy were assessed, and it was found that before intervention a jet formed in the throat of the coarctation, which impacted the arterial wall just downstream the constriction. After intervention the jet was significantly weaker and broke up almost immediately, presumably resulting in less stress on the wall. As there was a good agreement between measurements and numerical results (the increase and decrease of integrated TKE matched measurements almost perfectly while peak values differed by approximately 1mJ), the CFD results confirmed the MRI measurements while at the same time providing high-resolution details about the flow. Thus, this preliminary study indicates that MR-based TKE measurements might be useful as a diagnostic tool when evaluating intervention outcome, while the detailed numerical results might be useful for further understanding of the flow for treatment planning.
Asymptotic domination of cold relativistic MHD winds by kinetic energy flux
NASA Technical Reports Server (NTRS)
Begelman, Mitchell C.; Li, Zhi-Yun
1994-01-01
We study the conditions which lead to the conversion of most Poynting flux into kinetic energy flux in cold, relativistic hydromagnetic winds. It is shown that plasma acceleration along a precisely radial flow is extremely inefficient due to the near cancellation of the toroidal magnetic pressure and tension forces. However, if the flux tubes in a flow diverge even slightly faster than radially, the fast magnetosonic point moves inward from infinity to a few times the light cylinder radius. Once the flow becomes supermagnetosonic, further divergence of the flux tubes beyond the fast point can accelerate the flow via the 'magnetic nozzle' effect, thereby further converting Poynting flux to kinetic energy flux. We show that the Grad-Shafranov equation admits a generic family of kinetic energy-dominated asymptotic wind solutions with finite total magnetic flux. The Poynting flux in these solutions vanishes logarithmically with distance. The way in which the flux surfaces are nested within the flow depends only on the ratio of angular velocity to poliodal 4-velocity as a function of magnetic flux. Radial variations in flow structure can be expressed in terms of a pressure boundary condition on the outermost flux surface, provided that no external toriodal field surrounds the flow. For a special case, we show explicitly how the flux surfaces merge gradually to their asymptotes. For flows confined by an external medium of pressure decreasing to zero at infinity we show that, depending on how fast the ambient pressure declines, the final flow state could be either a collimated jet or a wind that fills the entire space. We discuss the astrophysical implications of our results for jets from active galactic nuclei and for free pulsar winds such as that believed to power the Crab Nebula.
Estimates of turbulent kinetic energy dissipation rate for a stratified flow in a wind tunnel
NASA Astrophysics Data System (ADS)
Puhales, Franciano Scremin; Demarco, Giuliano; Martins, Luis Gustavo Nogueira; Acevedo, Otávio Costa; Degrazia, Gervásio Annes; Welter, Guilherme Sausen; Costa, Felipe Denardin; Fisch, Gilberto Fernando; Avelar, Ana Cristina
2015-08-01
In this work a method to estimate turbulent kinetic energy dissipation rate (TKEDR) was presented. The technique uses the second-order structure function and Kolmogorov's law for inertial subrange. This methodology was applied on both neutral and stable stratification wind tunnel data, where the frozen turbulence hypothesis was assumed. The experiments were made with Reynolds Number ranging from 103 up to 104. The results show difference between the neutral and stable cases, but this gap decreases with the mean wind speed. Furthermore, TKEDR evaluated was used to describe the inertial subrange in the longitudinal velocity spectrum with a good agreement with the experimental data.
Effect of mean velocity shear on the dissipation rate of turbulent kinetic energy
NASA Technical Reports Server (NTRS)
Yoshizawa, Akira; Liou, Meng-Sing
1992-01-01
The dissipation rate of turbulent kinetic energy in incompressible turbulence is investigated using a two-scale DIA. The dissipation rate is shown to consist of two parts; one corresponds to the dissipation rate used in the current turbulence models of eddy-viscosity type, and another comes from the viscous effect that is closely connected with mean velocity shear. This result can elucidate the physical meaning of the dissipation rate used in the current turbulence models and explain part of the discrepancy in the near-wall dissipation rates between the current turbulence models and direct numerical simulation of the Navier-Stokes equation.
NASA Technical Reports Server (NTRS)
Kofsky, I. L.; Barrett, J. L.
1985-01-01
Laboratory experiments in which recombined CO, CO2, D2O, OH, N2, H2, and O2 molecules desorb from surfaces in excited internal and translational states are briefly reviewed. Unequilibrated distributions predominate from the principally catalytic metal substrates so far investigated. Mean kinetic energies have been observed up to approx. 3x, and in some cases less than, wall-thermal; the velocity distributions generally vary with emission angle, with non-Lambertian particle fluxes. The excitation state populations are found to depend on surface impurities, in an as yet unexplained way.
Method and turbine for extracting kinetic energy from a stream of two-phase fluid
NASA Technical Reports Server (NTRS)
Elliott, D. G. (Inventor)
1979-01-01
An axial flow separator turbine is described which includes a number of nozzles for delivering streams of a two-phase fluid along linear paths. A phase separator which responsively separates the vapor and liquid is characterized by concentrically related annuli supported for rotation within the paths. The separator has endless channels for confining the liquid under the influence of centrifugal forces. A vapor turbine fan extracts kinetic energy from the liquid. Angular momentum of both the liquid phase and the vapor phase of the fluid is converted to torque.
Kinetic energy releases of small amino acids upon interaction with keV ions
NASA Astrophysics Data System (ADS)
Bari, S.; Alvarado, F.; Postma, J.; Sobocinski, P.; Hoekstra, R.; Schlathölter, T.
2009-01-01
In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation of the gas-phase amino acids glycine, alanine and valine upon interaction with keV α-particles. High resolution coincidence time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies.
Anomalous dissipation and kinetic-energy distribution in pipes at very high Reynolds numbers
NASA Astrophysics Data System (ADS)
Chen, Xi; Wei, Bo-Bo; Hussain, Fazle; She, Zhen-Su
2016-01-01
A symmetry-based theory is developed for the description of (streamwise) kinetic energy K in turbulent pipes at extremely high Reynolds numbers (Re's). The theory assumes a mesolayer with continual deformation of wall-attached eddies which introduce an anomalous dissipation, breaking the exact balance between production and dissipation. An outer peak of K is predicted above a critical Re of 104, in good agreement with experimental data. The theory offers an alternative explanation for the recently discovered logarithmic distribution of K . The concept of anomalous dissipation is further supported by a significant modification of the k -ω equation, yielding an accurate prediction of the entire K profile.
Anomalous dissipation and kinetic-energy distribution in pipes at very high Reynolds numbers.
Chen, Xi; Wei, Bo-Bo; Hussain, Fazle; She, Zhen-Su
2016-01-01
A symmetry-based theory is developed for the description of (streamwise) kinetic energy K in turbulent pipes at extremely high Reynolds numbers (Re's). The theory assumes a mesolayer with continual deformation of wall-attached eddies which introduce an anomalous dissipation, breaking the exact balance between production and dissipation. An outer peak of K is predicted above a critical Re of 10^{4}, in good agreement with experimental data. The theory offers an alternative explanation for the recently discovered logarithmic distribution of K. The concept of anomalous dissipation is further supported by a significant modification of the k-ω equation, yielding an accurate prediction of the entire K profile.
Rabern, D.A.
1991-01-01
Three-dimensional numerical simulations were performed to determine the effect of an asymmetric base pressure on kinetic energy projectiles during launch. A matrix of simulations was performed in two separate launch environments. One launch environment represented a severe lateral load environment, while the other represented a nonsevere lateral load environment based on the gun tube straightness. The orientation of the asymmetric pressure field, its duration, the projectile's initial position, and the tube straightness were altered to determine the effects of each parameter. The pressure asymmetry translates down the launch tube to exit parameters and is washed out by tube profile. Results from the matrix of simulations are presented.
Rabern, D.A.
1991-12-31
Three-dimensional numerical simulations were performed to determine the effect of an asymmetric base pressure on kinetic energy projectiles during launch. A matrix of simulations was performed in two separate launch environments. One launch environment represented a severe lateral load environment, while the other represented a nonsevere lateral load environment based on the gun tube straightness. The orientation of the asymmetric pressure field, its duration, the projectile`s initial position, and the tube straightness were altered to determine the effects of each parameter. The pressure asymmetry translates down the launch tube to exit parameters and is washed out by tube profile. Results from the matrix of simulations are presented.
Graph-based analysis of kinetics on multidimensional potential-energy surfaces.
Okushima, T; Niiyama, T; Ikeda, K S; Shimizu, Y
2009-09-01
The aim of this paper is twofold: one is to give a detailed description of an alternative graph-based analysis method, which we call saddle connectivity graph, for analyzing the global topography and the dynamical properties of many-dimensional potential-energy landscapes and the other is to give examples of applications of this method in the analysis of the kinetics of realistic systems. A Dijkstra-type shortest path algorithm is proposed to extract dynamically dominant transition pathways by kinetically defining transition costs. The applicability of this approach is first confirmed by an illustrative example of a low-dimensional random potential. We then show that a coarse-graining procedure tailored for saddle connectivity graphs can be used to obtain the kinetic properties of 13- and 38-atom Lennard-Jones clusters. The coarse-graining method not only reduces the complexity of the graphs, but also, with iterative use, reveals a self-similar hierarchical structure in these clusters. We also propose that the self-similarity is common to many-atom Lennard-Jones clusters.
Rise kinetics of light-induced modulation of absorption for a CdS crystal
NASA Technical Reports Server (NTRS)
Long, E. R., Jr.; Conway, E. J.
1976-01-01
An experimental study has been made of the rise kinetics for changes in optical absorption in a single crystal of CdS which was bulk excited by pulsed laser light. The experimental data were compared to calculations from a simple model involving a bimolecular process. Experimental and calculated values agreed to within the experimental error and confirmed that light-induced modulation of absorption is a bimolecular process.
On energy balance and the structure of radiated waves in kinetics of crystalline defects
NASA Astrophysics Data System (ADS)
Sharma, Basant Lal
2016-11-01
Traveling waves, with well-known closed form expressions, in the context of the defects kinetics in crystals are excavated further with respect to their inherent structure of oscillatory components. These are associated with, so called, Frenkel-Kontorova model with a piecewise quadratic substrate potential, corresponding to the symmetric as well as asymmetric energy wells of the substrate, displacive phase transitions in bistable chains, and brittle fracture in triangular lattice strips under mode III conditions. The paper demonstrates that the power expended theorem holds so that the sum of rate of working and the rate of total energy flux into a control strip moving steadily with the defect equals the rate of energy sinking into the defect, in the sense of N.F. Mott. In the conservative case of the Frenkel-Kontorova model with asymmetric energy wells, this leads to an alternative expression for the mobility in terms of the energy flux through radiated lattice waves. An application of the same to the case of martensitic phase boundary and a crack, propagating uniformly in bistable chains and triangular lattice strips, respectively, is also provided and the energy release is expressed in terms of the radiated energy flux directly. The equivalence between the well-known expressions and their alternative is established via an elementary identity, which is stated and proved in the paper as the zero lemma. An intimate connection between the three distinct types of defects is, thus, revealed in the framework of energy balance, via a structural similarity between the corresponding variants of the 'zero' lemma containing the information about radiated energy flux. An extension to the dissipative models, in the presence of linear viscous damping, is detailed and analog of the zero lemma is proved. The analysis is relevant to the dynamics of dislocations, brittle cracks, and martensitic phase boundaries, besides possible applications to analogous physical contexts which are
Large-scale self-tuning solid-state kinetic energy harvester
NASA Astrophysics Data System (ADS)
Pletner, Baruch; Swan, Lukas; Wettels, Nicholas; Joseph, Alain
2012-04-01
In recent years there has been a strong emphasis on kinetic (vibration) energy harvesting using smart structure technology. This emphasis has been driven in large part by industry demand for powering sensors and wireless telemetry of sensor data in places into which running power and data cables is difficult or impossible. Common examples are helicopter drive shafts and other rotating equipment. In many instances, available space in these locations is highly limited, resulting in a trend for miniaturization of kinetic energy harvesters. While in some cases size limitations are dominant, in other cases large and even very large harvesters are possible and even desirable since they may produce significantly more power. Examples of large-scale energy harvesting include geomatics, which is the discipline of gathering, storing, processing, and delivering spatially referenced information on vast scales. Geomatics relies on suites of various sensors and imaging devices such as meteorological sensors, seismographs, high-resolution cameras, and LiDAR's. These devices may be stationed for prolonged periods of time in remote and poorly accessible areas and are required to operate continuously over prolonged periods of time. In other cases, sensing and imaging equipment may be mounted on land, sea, or airborne platforms and expected to operate for many hours on its own power. Providing power to this equipment constitutes a technological challenge. Other cases may include commercial buildings, unmanned powered gliders and more. Large scale kinetic energy harvesting thus constitutes a paradigm shift in the approach to kinetic energy harvesting as a whole and as often happens it poses its own unique technological challenges. Primarily these challenges fall into two categories: the cost-effective manufacturing of large and very large scale transducing elements based on smart structure technology and the continuous optimization (tuning) of these transducers for various operating
Wu, Jianlan; Tang, Zhoufei; Gong, Zhihao; Cao, Jianshu; Mukamel, Shaul
2015-04-02
The energy absorbed in a light-harvesting protein complex is often transferred collectively through aggregated chromophore clusters. For population evolution of chromophores, the time-integrated effective rate matrix allows us to construct quantum kinetic clusters quantitatively and determine the reduced cluster-cluster transfer rates systematically, thus defining a minimal model of energy-transfer kinetics. For Fenna-Matthews-Olson (FMO) and light-havrvesting complex II (LCHII) monomers, quantum Markovian kinetics of clusters can accurately reproduce the overall energy-transfer process in the long-time scale. The dominant energy-transfer pathways are identified in the picture of aggregated clusters. The chromophores distributed extensively in various clusters can assist a fast and long-range energy transfer.
Abaïdia, Abd-Elbasset; Delecroix, Barthélémy; Leduc, Cédric; Lamblin, Julien; McCall, Alan; Baquet, Georges; Dupont, Grégory
2017-01-01
Abaïdia, A-E, Delecroix, B, Leduc, C, Lamblin, J, McCall, A, Baquet, G, and Dupont, G. Effects of a strength training session after an exercise inducing muscle damage on recovery kinetics. J Strength Cond Res 31(1): 115-125, 2017-The purpose of this study was to investigate the effects of an upper-limb strength training session the day after an exercise inducing muscle damage on recovery of performance. In a randomized crossover design, subjects performed the day after the exercise, on 2 separate occasions (passive vs. active recovery conditions) a single-leg exercise (dominant in one condition and nondominant in the other condition) consisting of 5 sets of 15 eccentric contractions of the knee flexors. Active recovery consisted of performing an upper-body strength training session the day after the exercise. Creatine kinase, hamstring strength, and muscle soreness were assessed immediately and 20, 24, and 48 hours after exercise-induced muscle damage. The upper-body strength session, after muscle-damaging exercise accelerated the recovery of slow concentric force (effect size = 0.65; 90% confidence interval = -0.06 to 1.32), but did not affect the recovery kinetics for the other outcomes. The addition of an upper-body strength training session the day after muscle-damaging activity does not negatively affect the recovery kinetics. Upper-body strength training may be programmed the day after a competition.
On the Exchange of Kinetic and Magnetic Energy between Clouds and the Interstellar Medium
NASA Astrophysics Data System (ADS)
Miniati, Francesco; Jones, T. W.; Ryu, Dongsu
1999-05-01
We investigate, through two-dimensional MHD numerical simulations, the interaction of a uniform magnetic field oblique to a moving interstellar cloud. In particular we explore the transformation of cloud kinetic energy into magnetic energy as a result of field line stretching. Some previous simulations have emphasized the possible dynamical importance of a ``magnetic shield'' formed around clouds when the magnetic field is perpendicular to the cloud motion. It was not clear, however, how dependent those findings were on the assumed field configuration and cloud properties. To expand our understanding of this effect, we examine several new cases by varying the magnetic field orientation angle with respect to the cloud motion (θ), the cloud-background density contrast, and the cloud Mach number. We show that in two dimensions and with θ large enough, the magnetic field tension can become dominant in the dynamics of the motion of high density contrast, low Mach number clouds. In such a case, a significant fraction of the cloud's kinetic energy can be transformed into magnetic energy with the magnetic pressure at the cloud's nose exceeding the ram pressure of the impinging flow. We derive a characteristic timescale, τma, for this process of energy ``conversion.'' We find also that unless the cloud motion is highly aligned with the magnetic field, reconnection through tearing-mode instabilities in the cloud wake limits the formation of a strong flux-rope feature following the cloud. Finally we attempt to interpret some observed properties of the magnetic field in view of our results.
Fritzius, Thorsten; Turecek, Rostislav; Seddik, Riad; Kobayashi, Hiroyuki; Tiao, Jim; Rem, Pascal D; Metz, Michaela; Kralikova, Michaela; Bouvier, Michel; Gassmann, Martin; Bettler, Bernhard
2017-02-01
GABAB receptors are the G-protein coupled receptors for the main inhibitory neurotransmitter in the brain, GABA. GABAB receptors were shown to associate with homo-oligomers of auxiliary KCTD8, KCTD12, KCTD12b, and KCTD16 subunits (named after their T1 K(+)-channel tetramerization domain) that regulate G-protein signaling of the receptor. Here we provide evidence that GABAB receptors also associate with hetero-oligomers of KCTD subunits. Coimmunoprecipitation experiments indicate that two-thirds of the KCTD16 proteins in the hippocampus of adult mice associate with KCTD12. We show that the KCTD proteins hetero-oligomerize through self-interacting T1 and H1 homology domains. Bioluminescence resonance energy transfer measurements in live cells reveal that KCTD12/KCTD16 hetero-oligomers associate with both the receptor and the G-protein. Electrophysiological experiments demonstrate that KCTD12/KCTD16 hetero-oligomers impart unique kinetic properties on G-protein-activated Kir3 currents. During prolonged receptor activation (one min) KCTD12/KCTD16 hetero-oligomers produce moderately desensitizing fast deactivating K(+) currents, whereas KCTD12 and KCTD16 homo-oligomers produce strongly desensitizing fast deactivating currents and nondesensitizing slowly deactivating currents, respectively. During short activation (2 s) KCTD12/KCTD16 hetero-oligomers produce nondesensitizing slowly deactivating currents. Electrophysiological recordings from hippocampal neurons of KCTD knock-out mice are consistent with these findings and indicate that KCTD12/KCTD16 hetero-oligomers increase the duration of slow IPSCs. In summary, our data demonstrate that simultaneous assembly of distinct KCTDs at the receptor increases the molecular and functional repertoire of native GABAB receptors and modulates physiologically induced K(+) current responses in the hippocampus.
Kinetic model of stimulated emission created by resonance pumping of aluminum laser-induced plasma
NASA Astrophysics Data System (ADS)
Gornushkin, I. B.; Kazakov, A. Ya.
2017-06-01
Stimulated emission observed experimentally in an aluminum laser induced plasma is modeled via a kinetic approach. The simulated emission at several cascade transitions is created by a pump laser guided through the plasma at several microseconds after its creation and tuned in resonance with the strong 3s23p-3s24s transition at 266 nm. A two-dimensional space-time collisional radiative plasma model explains the creation of the population inversion and lasing at wavelengths of 2100 n m and 396.1 nm. The population inversion for lasing at 2100 n m is created by depopulation of the ground 3s23p state and population of the 3s25s state via the absorption of the resonant radiation at 266 nm. The population inversion for lasing at 396.1 nm occurs during the laser pulse via the decay of the population of the pumped 3s25s state to the excited 3s24s state via cascade transitions driven optically and by collisions. In particular, efficient are the mixing transitions between neighboring states separated by small gaps on the order of k T at plasma temperatures of 5000-10 000 K. The model predicts that the population inversion and corresponding gain may reach high values even at very moderate pump energy of several μJ per pulse. The efficiency of lasing at 2100 n m and 396.1 nm is estimated to be ˜3% and 0.05%, correspondingly with respect to the pump laser intensity. The gain for lasing at 396.1 nm can reach as high as ˜40 cm-1. The polarization effect that the pump radiation at 266 nm imposes on the stimulated emission at 396.1 nm is discussed. The calculated results are favorably compared to experimental data.
Kinetic energy of shakeoff atomic electrons from 37K β+ decay
NASA Astrophysics Data System (ADS)
Behr, J. A.; Gorelov, A.; Farfan, C.; Smale, S.; Olchanski, K.; Kurchananov, L.; Anholm, M.; Behling, R. S.; Fenker, B.; Shidling, P. D.; Mehlman, M.; Melconian, D.; Ashery, D.; Gwinner, G.; Trinat Collaboration
2013-10-01
We have measured the kinetic energies from 0 to 30 eV of atomic shakeoff electrons from the β+ decay of 37K. Despite much experimental and theoretical work on the distribution of final ion charge states, shakeoff electrons from β- decay have only been measured with energies above 150 eV [Mitrokhovich, Nucl. Phys. Atom. Energy, 11, 125 (2010)]. We use our magneto-optical trap's time-varying magnetic quadrupole field combined with a uniform electric field as a spectrometer. Our result has more 15 eV electrons than a model using the sudden approximation and hydrogenic wavefunctions [Levinger, Phys. Rev. 90, 11 (1958)]. The total energy carried away by electrons is, as expected, a negligible correction to superallowed Ft values. Understanding the energy of these low-energy electrons is important for their use in precision β decay to select events coming from trapped atoms and start time-of-flight for the recoil ions. Our results could provide a benchmark for shakeoff electron calculations used for biological radiation damage [Lee, Comp. Math. Meth in Medicine doi:10.1155/2012/651475]. Support: NSERC, NRC through TRIUMF, DOE ER41747 ER40773, State of Texas, Israel Science Foundation.
Sengbusch, E; Pérez-Andújar, A; DeLuca, P M; Mackie, T R
2009-02-01
Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180 degrees continuous arc proton therapy and for 180 degrees split arc proton therapy (two 90 degrees arcs) using CT# profiles from the Pinnacle (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the
Sengbusch, E.; Pérez-Andújar, A.; DeLuca, P. M.; Mackie, T. R.
2009-01-01
Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy of protons, immediately prior to entry into the patient, that must be reached by the treatment system. The commonly used value for the maximum kinetic energy required for a medical proton accelerator is 250 MeV, but it has not been demonstrated that this energy is indeed necessary to treat all or most patients eligible for proton therapy. This article quantifies the maximum kinetic energy of protons, immediately prior to entry into the patient, necessary to treat a given percentage of patients with rotational proton therapy, and examines the impact of this energy threshold on the cost and feasibility of a compact, gantry-mounted proton accelerator treatment system. One hundred randomized treatment plans from patients treated with IMRT were analyzed. The maximum radiological pathlength from the surface of the patient to the distal edge of the treatment volume was obtained for 180° continuous arc proton therapy and for 180° split arc proton therapy (two 90° arcs) using CT# profiles from the Pinnacle™ (Philips Medical Systems, Madison, WI) treatment planning system. In each case, the maximum kinetic energy of protons, immediately prior to entry into the patient, that would be necessary to treat the patient was calculated using proton range tables for various media. In addition, Monte Carlo simulations were performed to quantify neutron production in a water phantom representing a patient as a function of the maximum proton kinetic energy achievable by a proton treatment system. Protons with a kinetic energy of 240 MeV, immediately prior to entry into the patient, were needed to treat 100% of patients in this study. However, it was shown that 90% of patients could be treated at 198 MeV, and 95% of patients could be treated at 207 MeV. Decreasing the proton kinetic
Calorimetric study of the energy efficiency for ultrasound-induced radical formation.
Kuijpers, M W A; Kemmere, M F; Keurentjes, J T F
2002-05-01
Energy conversion in sonochemistry is known to be an important factor for the development of industrial applications, however, the strong influence of the physical properties of the liquid on the ultrasound characteristics usually prevents an accurate determination of the chemical effects. In this study, the energy efficiency of the ultrasound-induced radical formation from methyl methacrylate has been investigated. The energy yield can be quantified by comparison of the ultrasonic power that is transferred to the liquid and the radical formation kinetics. Based on this method the influence of temperature and amplitude of the ultrasound horn on the energy efficiency has been determined. The energy yield for the formation of radicals from ultrasonic waves appears to be in the order of 5 x 10(-6) J/J. The energy conversion is the highest at low temperatures and at low amplitudes.
Kinetic modeling and energy efficiency of UV/H₂O₂ treatment of iodinated trihalomethanes.
Xiao, Yongjun; Zhang, Lifeng; Yue, Junqi; Webster, Richard D; Lim, Teik-Thye
2015-05-15
Photodegradation of I-THMs including CHCl2I and CHI3 by the UV/H2O2 system was investigated in this study. CHCl2I and CHI3 react rapidly with hydroxyl radical (OH) produced by the UV/H2O2 system, with second-order rate constants of 8.0 × 10(9) and 8.9 × 10(9) M(-1) s(-1), respectively. A fraction of CHCl2I could be completely mineralized within 15 min and the remaining fraction was mainly converted to formic acid (HCO2H). Cl(-) and I(-) were identified as the predominant end-products. No ClO3(-) was observed during the photodegradation process, while IO3(-) was detected but at less than 2% of the total liberated iodine species at the end of the reaction. The effects of pH, H2O2 dose, and matrix species such as humic acid (HA), HCO3(-), SO4(2-), Cl(-), NO3(-) on the photodegradation kinetics were evaluated. The steady-state kinetic model has been proven to successfully predict the destruction of CHCl2I and CHI3 by UV/H2O2 in different water matrices. On this basis, the kinetic model combined with electrical energy per order (EE/O) concept was applied to evaluate the efficiency of the photodegradation process and to optimize the H2O2 dose for different scenarios. The optimal H2O2 doses in deionized (DI) water, model natural water, and surface water are estimated at 5, 12, and 16 mg L(-1), respectively, which correspond to the lowest total energy consumption (EE/Ototal) of 0.2, 0.31, and 0.45 kWhm(-3)order(-1). Copyright © 2015 Elsevier Ltd. All rights reserved.
Current redistribution and generation of kinetic energy in the stagnated Z pinch.
Ivanov, V V; Anderson, A A; Papp, D; Astanovitskiy, A L; Talbot, B R; Chittenden, J P; Niasse, N
2013-07-01
The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%.
Koitaya, Takanori; Shimizu, Sumera; Mukai, Kozo; Yoshimoto, Shinya; Yoshinobu, Jun
2012-06-07
Novel isotope effects were observed in desorption kinetics and adsorption geometry of cyclohexane on Rh(111) by the use of infrared reflection absorption spectroscopy, temperature programmed desorption, photoelectron spectroscopy, and spot-profile-analysis low energy electron diffraction. The desorption energy of deuterated cyclohexane (C(6)D(12)) is lower than that of C(6)H(12). In addition, the work function change by adsorbed C(6)D(12) is smaller than that by adsorbed C(6)H(12). These results indicate that C(6)D(12) has a shallower adsorption potential than C(6)H(12) (vertical geometric isotope effect). The lateral geometric isotope effect was also observed in the two-dimensional cyclohexane superstructures as a result of the different repulsive interaction between interfacial dipoles. The observed isotope effects should be ascribed to the quantum nature of hydrogen involved in the C-H···metal interaction.
Enhancing Understanding of High Energy Density Plasmas Using Fluid Modeling with Kinetic Closures
NASA Astrophysics Data System (ADS)
Hansen, David; Held, Eric; Srinivasan, Bhuvana; Masti, Robert; King, Jake
2016-10-01
This work seeks to understand possible stabilization mechanisms of the early-time electrothermal instability in the evolution of the Rayleigh-Taylor instability in MagLIF (Magnetized Liner Inertial Fusion) experiments. Such mechanisms may include electron thermal conduction, viscosity, and large magnetic fields. Experiments have shown that the high-energy density plasmas from wire-array implosions require physics modelling that goes well beyond simple models such as ideal MHD. The plan is to develop a multi-fluid extended-MHD model that includes kinetic closures for thermal conductivity, resistivity, and viscosity using codes that are easily available to the wider research community. Such an effort would provide the community with a well-benchmarked tool capable of advanced modeling of high-energy-density plasmas.
Cars and Kinetic Energy -- Some Simple Physics with Real-World Relevance
NASA Astrophysics Data System (ADS)
Parthasarathy, Raghuveer
2012-10-01
Understanding energy usage is crucial to understanding modern civilization, as well as many of the challenges it faces. Energy-related issues also offer real-world examples of important physical concepts, and as such have been the focus of several articles in The Physics Teacher in the past few decades (e.g., Refs. 1-5, noted further below). Here, I illustrate how a basic understanding of kinetic energy—a topic encountered early in any introductory physics course—enables significant insights into the nature of automobile transportation. Specifically, we can accurately predict how much power the average driver in the United States uses, and explain what determines this, without needing to consider any aspects of mechanical engineering or engine design.
Dependence of single-walled carbon nanotube adsorption kinetics on temperature and binding energy.
Rawat, D S; Krungleviciute, V; Heroux, L; Bulut, M; Calbi, M M; Migone, A D
2008-12-02
We present results for the isothermal adsorption kinetics of methane, hydrogen, and tetrafluoromethane on closed-ended single-walled carbon nanotubes. In these experiments, we monitor the pressure decrease as a function of time as equilibrium is approached, after a dose of gas is added to the cell containing the nanotubes. The measurements were performed at different fractional coverages limited to the first layer. The results indicate that, for a given coverage and temperature, the equilibration time is an increasing function of E/(k(B)T), where E is the binding energy of the adsorbate and k(B)T is the thermal energy. These findings are consistent with recent theoretical predictions and computer simulations results that we use to interpret the experimental measurements.
Damage detection via closed-form sensitivity matrix of modal kinetic energy change ratio
NASA Astrophysics Data System (ADS)
Hadjian Shahri, A. H.; Ghorbani-Tanha, A. K.
2017-08-01
In this paper, a new damage detection method based on a damage sensitive feature parameter named Modal Kinetic Energy Change Ratio has been proposed. The sensitivity matrix for the damage identification procedure is calculated by making use of the closed-form sensitivity of eigenvalues of the structure. Numerical simulations and experimental tests were carried out on a beam-like structure in order to examine the reliability and feasibility of the proposed method. System Equivalent Reduction Expansion Technique is employed to omit rotational degrees of freedom of the model. It is demonstrated that this method locates and quantifies structural damage(s) with acceptable accuracy. The best advantage of the proposed method comparing to the ones which are based on modal strain energy is that it is not sensitive to mode shape noise and yields favorable results under moderate noise in natural frequencies.
Kinetic description of charmonium production in high-energy nuclear collisions
Polleri, Alberto; Weise, Wolfram; Renk, Thorsten; Schneider, Roland
2004-10-01
We study the evolution of charmonia as they collide with the constituents of the fireball produced in high-energy nucleus-nucleus collisions. The latter evolves in a manner controlled by the equation of state as given by lattice QCD, and is constructed in such a way that the observed hadronic spectra are correctly reproduced. A kinetic description of charmonium interactions with both quark-gluon and hadronic degrees of freedom allows us to study in detail the evolution in different regimes, controlled by collision energy, kinematics, and geometry. The data collected at the CERN-SPS accelerator are well described and new estimates for J/{psi} production at BNL-RHIC are presented.
Low-energy signals from kinetic mixing with a warped abelian hidden sector
NASA Astrophysics Data System (ADS)
McDonald, Kristian L.; Morrissey, David E.
2011-02-01
We investigate the detailed phenomenology of a light Abelian hidden sector in the Randall-Sundrum framework. Relative to other works with light hidden sectors, the main new feature is a tower of hidden Kaluza-Klein vectors that kinetically mix with the Standard Model photon and Z. We investigate the decay properties of the hidden sector fields in some detail, and develop an approach for calculating processes initiated on the ultraviolet brane of a warped space with large injection momentum relative to the infrared scale. Using these results, we determine the detailed bounds on the light warped hidden sector from precision electroweak measurements and low-energy experiments. We find viable regions of parameter space that lead to significant production rates for several of the hidden Kaluza-Klein vectors in meson factories and fixed-target experiments. This offers the possibility of exploring the structure of an extra spacetime dimension with lower-energy probes.
NASA Astrophysics Data System (ADS)
Joung, M. K. R.; Mac Low, M.-M.
2005-12-01
We construct three-dimensional models of stratified interstellar medium stirred by discrete supernova explosions, including vertical gravitational field and parameterized heating and cooling, with sufficient spatial resolution to follow detailed gas dynamics using a grid-based adaptive mesh refinement code, Flash. The models reproduce observed characteristics of the Galaxy such as the galactic fountain and cold dense clouds in the galactic disk. We find: (1) Kinetic energy is distributed over a broad range of lengths, but 90% of the total kinetic energy is contained in wavelengths shortward of 150 pc; (2) Turbulent velocity dispersion is inversely proportional to the square root of the local density, making the turbulent pressure nearly constant; (3) The global gas structure depends sensitively on the assumed background diffuse heating rate. We discuss how these high-resolution models can be used as a subgrid model for supernova feedback in global simulations of galaxies. MKRJ was supported by an AMNH Graduate Student Fellowship. M-MML acknowledges support by NSF Career grant AST99-85392, and NSF grants AST03-07793, AST03-07854. The software used in this work was in part developed by the DOE-supported ASCI/Alliance Center for Astrophysical Thermonuclear Flashes at the University of Chicago. Computations were performed at the Pittsburgh Supercomputing Center supported by the NSF.
Hypovalency--a kinetic-energy density description of a 4c-2e bond.
Jacobsen, Heiko
2009-06-07
A bond descriptor based on the kinetic energy density, the localized-orbital locator (LOL), is used to characterize the nature of the chemical bond in electron deficient multi-center bonds. The boranes B(2)H(6), B(4)H(4), B(4)H(10), [B(6)H(6)](2-), and [B(6)H(7)](-) serve as prototypical examples of hypovalent 3c-2e and 4c-2e bonding. The kinetic energy density is derived from a set of Kohn-Sham orbitals obtained from pure density functional calculations (PBE/TZVP), and the topology of LOL is analyzed in terms of (3,-3) attractors (Gamma). The B-B-B and B-H-B 3c-2e, and the B-B-H-B 4c-2e bonding situations are defined by their own characteristic LOL profiles. The presence of one attractor in relation to the three or four atoms that are engaged in electron deficient bonding provides sufficient indication of the type of 3c-2e or 4c-2e bond present. For the 4c-2e bond in [B(6)H(7)](-) the LOL analysis is compared to results from an experimental QTAIM study.
Energy Transfer Kinetics in Photosynthesis as an Inspiration for Improving Organic Solar Cells.
Nganou, Collins; Lackner, Gerhard; Teschome, Bezu; Deen, M Jamal; Adir, Noam; Pouhe, David; Lupascu, Doru C; Mkandawire, Martin
2017-06-07
Clues to designing highly efficient organic solar cells may lie in understanding the architecture of light-harvesting systems and exciton energy transfer (EET) processes in very efficient photosynthetic organisms. Here, we compare the kinetics of excitation energy tunnelling from the intact phycobilisome (PBS) light-harvesting antenna system to the reaction center in photosystem II in intact cells of the cyanobacterium Acaryochloris marina with the charge transfer after conversion of photons into photocurrent in vertically aligned carbon nanotube (va-CNT) organic solar cells with poly(3-hexyl)thiophene (P3HT) as the pigment. We find that the kinetics in electron hole creation following excitation at 600 nm in both PBS and va-CNT solar cells to be 450 and 500 fs, respectively. The EET process has a 3 and 14 ps pathway in the PBS, while in va-CNT solar cell devices, the charge trapping in the CNT takes 11 and 258 ps. We show that the main hindrance to efficiency of va-CNT organic solar cells is the slow migration of the charges after exciton formation.
NASA Technical Reports Server (NTRS)
Kim, S.-W.; Chen, C.-P.
1987-01-01
A multiple-time-scale turbulence model of a single point closure and a simplified split-spectrum method is presented. In the model, the effect of the ratio of the production rate to the dissipation rate on eddy viscosity is modeled by use of the multiple-time-scales and a variable partitioning of the turbulent kinetic energy spectrum. The concept of a variable partitioning of the turbulent kinetic energy spectrum and the rest of the model details are based on the previously reported algebraic stress turbulence model. Example problems considered include: a fully developed channel flow, a plane jet exhausting into a moving stream, a wall jet flow, and a weakly coupled wake-boundary layer interaction flow. The computational results compared favorably with those obtained by using the algebraic stress turbulence model as well as experimental data. The present turbulence model, as well as the algebraic stress turbulence model, yielded significantly improved computational results for the complex turbulent boundary layer flows, such as the wall jet flow and the wake boundary layer interaction flow, compared with available computational results obtained by using the standard kappa-epsilon turbulence model.
Kinetic energy density and agglomerate abrasion rate during blending of agglomerates into powders.
Willemsz, Tofan A; Hooijmaijers, Ricardo; Rubingh, Carina M; Tran, Thanh N; Frijlink, Henderik W; Vromans, Herman; van der Voort Maarschalk, Kees
2012-01-23
Problems related to the blending of a cohesive powder with a free flowing bulk powder are frequently encountered in the pharmaceutical industry. The cohesive powder often forms lumps or agglomerates which are not dispersed during the mixing process and are therefore detrimental to blend uniformity. Achieving sufficient blend uniformity requires that the blending conditions are able to break up agglomerates, which is often an abrasion process. This study was based on the assumption that the abrasion rate of agglomerates determines the required blending time. It is shown that the kinetic energy density of the moving powder bed is a relevant parameter which correlates with the abrasion rate of agglomerates. However, aspects related to the strength of agglomerates should also be considered. For this reason the Stokes abrasion number (St(Abr)) has been defined. This parameter describes the ratio between the kinetic energy density of the moving powder bed and the work of fracture of the agglomerate. The St(Abr) number is shown to predict the abrasion potential of agglomerates in the dry-mixing process. It appeared possible to include effects of filler particle size and impeller rotational rate into this concept. A clear relationship between abrasion rate of agglomerates and the value of St(Abr) was demonstrated.
A kinetic energy model of two-vehicle crash injury severity.
Sobhani, Amir; Young, William; Logan, David; Bahrololoom, Sareh
2011-05-01
An important part of any model of vehicle crashes is the development of a procedure to estimate crash injury severity. After reviewing existing models of crash severity, this paper outlines the development of a modelling approach aimed at measuring the injury severity of people in two-vehicle road crashes. This model can be incorporated into a discrete event traffic simulation model, using simulation model outputs as its input. The model can then serve as an integral part of a simulation model estimating the crash potential of components of the traffic system. The model is developed using Newtonian Mechanics and Generalised Linear Regression. The factors contributing to the speed change (ΔV(s)) of a subject vehicle are identified using the law of conservation of momentum. A Log-Gamma regression model is fitted to measure speed change (ΔV(s)) of the subject vehicle based on the identified crash characteristics. The kinetic energy applied to the subject vehicle is calculated by the model, which in turn uses a Log-Gamma Regression Model to estimate the Injury Severity Score of the crash from the calculated kinetic energy, crash impact type, presence of airbag and/or seat belt and occupant age.
NASA Astrophysics Data System (ADS)
Lantz, Jonas; Ebbers, Tino; Karlsson, Matts
2012-11-01
In this study, turbulent kinetic energy (TKE) in an aortic coarctation was studied using both a numerical technique (large eddy simulation, LES) and in vivo measurements using magnetic resonance imaging (MRI). High levels of TKE are undesirable, as kinetic energy is extracted from the mean flow to feed the turbulent fluctuations. The patient underwent surgery to widen the coarctation, and the flow before and after surgery was computed and compared to MRI measurements. The resolution of the MRI was about 7 × 7 voxels in axial cross-section while 50x50 mesh cells with increased resolution near the walls was used in the LES simulation. In general, the numerical simulations and MRI measurements showed that the aortic arch had no or very low levels of TKE, while elevated values were found downstream the coarctation. It was also found that TKE levels after surgery were lowered, indicating that the diameter of the constriction was increased enough to decrease turbulence effects. In conclusion, both the numerical simulation and MRI measurements gave very similar results, thereby validating the simulations and suggesting that MRI measured TKE can be used as an initial estimation in clinical practice, while LES results can be used for detailed quantification and further research of aortic flows.
Fully-kinetic simulations of the Rayleigh-Taylor instability in high-energy-density plasmas
NASA Astrophysics Data System (ADS)
Alves, E. Paulo; Mori, Warren B.; Fiuza, Frederico
2016-10-01
The Rayleigh-Taylor instability (RTI) in high-energy-density (HED) plasmas is a central problem in a wide range of scenarios. It dictates, for instance, the dynamics of supernovae in astrophysical plasmas, and is also recognized as a critical challenge to achieving ignition in inertial confinement fusion. In some of these conditions the Larmor radius or Coulomb mean free path (m.f.p.) is finite, allowing kinetic effects to become important, and it is not fully clear how the development of the RTI deviates from standard hydrodynamic behavior. In order to obtain an accurate description of the RTI in these HED conditions it is essential to capture the self-consistent interplay between collisional and collisionless plasma processes, and the role of self-generated electric and magnetic fields. We have explored the dynamics of the RTI in HED plasma conditions using first-principles particle-in-cell simulations combined with Monte Carlo binary collisions. Our simulations capture the role of kinetic diffusion as well as the self-generated electric (e.g. space-charge) and magnetic (e.g. Biermann battery) fields on the growth rate and nonlinear evolution of the RTI for different plasma conditions. We will discuss how different collisional m.f.p. relative to the collisionless plasma skin depth affect the RTI development. This work was supported by the DOE Office of Science, Fusion Energy Science (FWP 100182).
The Effects of Kinetic Energy on Concentric and Eccentric Isokinetic Work
Boggess, Brian; Moffit, Jeff; Morales, Jacobo; Anderson, Tim
2008-01-01
This investigation examined inertial effects on work output during isokinetic concentric knee extension and eccentric knee flexion. Total work (Wtotal) included work due to kinetic energy (Wkin), with respect to gravity (Wgrav), and against the dynamometer (Wdyn). Eighteen resistance-trained participants (9 males, 9 females) performed maximal voluntary concentric (90, 150, 210, 270 deg/s) and eccentric (-150, -90, -30 deg/s) actions with the dominant leg. Differences between work measurement type (WMT), i.e., gravity-corrected work and Wtotal, were assessed. ANOVA (2 WMT x 2 mode x 2 gender x 4 speed) revealed significant main effects (p < 0. 05) for both factors concentrically but only for WMT eccentrically. It was concluded that the effect of kinetic energy during isokinetic leg extension may elicit differences in measurement where the associated error (Kerr) significantly increases with increasing velocity concentrically and decreases eccentrically. Key pointsTotal isokinetic work is underestimated by standard gravity corrected techniques.Standard gravity corrected work measurements overestimate isometric eccentric total work.The overestimation of isometric eccentric total work increases with greater angular velocity. PMID:24150138
Kinetic analysis and energy efficiency of phenol degradation in a plasma-photocatalysis system.
Wang, Hui-juan; Chen, Xiao-yang
2011-02-28
Combination of two kinds of advanced oxidation processes (AOPs) is an effective approach to control wastewater pollution. In this research, a pulsed discharge plasma system with multi-point-to-plate electrode and an immobilized TiO(2) photocatalysis system is coupled to oxidize target pollutant in aqueous solution. Kinetic analysis (pseudo-first order kinetic constant, k) and energy efficiency (energy yield value at 50% phenol conversion, G(50)) of phenol oxidation in different reaction systems (plasma alone and plasma-photocatalysis) are reviewed to account for the synergistic mechanism of plasma and photocatalysis. The experimental results show that higher k and G(50) of phenol oxidation can be obtained in the plasma-photocatalysis system under the conditions of different gas bubbling varieties, initial solution pH and radical scavenger addition. Moreover, the investigation tested hydroxyl radical (OH) is the most important species for phenol removal in the synergistic system of plasma-photocatalysis as well as in the plasma alone system.
Kinetic energy entrainment in wind turbine and actuator disc wakes: an experimental analysis
NASA Astrophysics Data System (ADS)
Lignarolo, L. E. M.; Ragni, D.; Simão Ferreira, C. J.; van Bussel, G. J. W.
2014-06-01
The present experimental study focuses on the comparison between the wake of a two-bladed wind turbine and the one of an actuator disk. The flow field at the middle plane of the wake is measured with a stereoscopic particle image velocimetry setup, in the low-speed Open Jet Facility wind tunnel of the Delft University of Technology. The wind turbine wake is characterized by the complex dynamics of the tip vortex development and breakdown. Analysis of the flow statistics show anisotropic turbulent fluctuations in the turbine wake, with stronger components in the radial direction. The wake of the actuator disc is instead characterized by isotropic random fluctuations. The mixing process in the shear layer is further analysed in terms of flux of mean flow kinetic energy, to show the main differences between the kinetic energy entrainment in the actuator and the turbine wake. This project is intended to provide the basis for understanding the origin of the limitations of the current wake models based on the actuator disc assumption.
NASA Astrophysics Data System (ADS)
Shantappa, A.; Hanagodimath, S. M.
2014-01-01
Effective atomic numbers, electron densities of some vitamins (Retinol, Riboflavin, Niacin, Biotin, Folic acid, Cobalamin, Phylloquinone and Flavonoids) composed of C, H, O, N, Co, P and S have been calculated for total and partial photon interactions by the direct method for energy range 1 keV-100 GeV by using WinXCOM and kinetic energy released in matter (Kerma) relative to air is calculated in energy range of 1 keV-20 MeV. Change in effective atomic number and electron density with energy is calculated for all photon interactions. Variation of photon mass attenuation coefficients with energy are shown graphically only for total photon interaction. It is observed that change in mass attenuation coefficient with composition of different chemicals is very large below 100 keV and moderate between 100 keV and 10 MeV and negligible above 10 MeV. Behaviour of vitamins is almost indistinguishable except biotin and cobalamin because of large range of atomic numbers from 1(H) to 16 (S) and 1(H) to 27(Co) respectively. K a value shows a peak due to the photoelectric effect around K-absorption edge of high- Z constituent of compound for biotin and cobalamin.
Young, R M; Arnette, J K; Roess, D A; Barisas, B G
1994-01-01
We describe practical aspects of photobleaching fluorescence energy transfer measurements on individual living cells. The method introduced by T. M. Jovin and co-workers (see, most recently, Kubitscheck et al. 1993. Biophys. J. 64:110) is based on the reduced rate of irreversible photobleaching of donor fluorophores when acceptor fluorophores are present. Measuring differences in donor photobleaching rates on cells labeled with donor only (fluorescein isothiocyanate-conjugated proteins) and with both donor and acceptor (tetramethylrhodamine-conjugated proteins) allows calculation of the fluorescence energy transfer efficiency. We assess possible methods of data analysis in light of the underlying processes of photobleaching and energy transfer and suggest optimum strategies for this purpose. Single murine B lymphocytes binding various ratios of donor and acceptor conjugates of tetravalent concanavalin A (Con A) and divalent succinyl Con A were examined for interlectin energy transfer by these methods. For Con A, a maximum transfer efficiency of 0.49 +/- 0.02 was observed. Under similar conditions flow cytometric measurements of donor quenching yielded a value of 0.54 +/- 0.03. For succinyl Con A, the maximum transfer efficiency was 0.36. To provide concrete examples of quantities arising in such energy transfer determinations, we present examples of individual cell data and kinetic analyses, population rate constant distributions, and error estimates for the various quantities involved. PMID:7948701
NASA Astrophysics Data System (ADS)
Kohnert, Aaron Anthony
The mechanical properties of materials are often degraded over time by exposure to irradiation environments, a phenomenon that has hindered the development of multiple nuclear reactor design concepts. Such property changes are the result of microstructural changes induced by the collision of high energy particles with the atoms in a material. The lattice defects generated in these recoil events migrate and interact to form extended damage structures. This study has used theoretical models based on the mean field chemical reaction rate theory to analyze the aggregation of isolated lattice defects into larger microstructural features that are responsible for long term property changes, focusing on the development of black dot damage in ferritic iron based alloys. The purpose of such endeavors is two-fold. Primarily, such models explain and quantify the processes through which these microstructures form. Additionally, models provide insight into the behavior and properties of the point defects and defect clusters which drive general microstructural evolution processes. The modeling effort presented in this work has focused on physical fidelity, drawing from a variety of sources of information to characterize the unobservable defect generation and agglomeration processes that give rise to the observable features reported in experimental data. As such, the models are based not solely on isolated point defect creation, as is the case with many older rate theory approaches, but instead on realistic estimates of the defect cluster population produced in high energy cascade damage events. Experimental assessments of the microstructural changes evident in transmission electron microscopy studies provide a means to measure the efficacy of the kinetic models. Using common assumptions of the mobility of defect clusters generated in cascade damage conditions, an unphysically high density of damage features develops at the temperatures of interest with a temperature dependence
NASA Astrophysics Data System (ADS)
Gorlé, C.; van Beeck, J.; Rambaud, P.; Van Tendeloo, G.
When considering the modelling of small particle dispersion in the lower part of the Atmospheric Boundary Layer (ABL) using Reynolds Averaged Navier Stokes simulations, the particle paths depend on the velocity profile and on the turbulence kinetic energy, from which the fluctuating velocity components are derived to predict turbulent dispersion. It is therefore important to correctly reproduce the ABL, both for the velocity profile and the turbulence kinetic energy profile. For RANS simulations with the standard k- ɛ model, Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the k-ɛ turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46-47, 145-153.) proposed a set of boundary conditions which result in horizontally homogeneous profiles. The drawback of this method is that it assumes a constant profile of turbulence kinetic energy, which is not always consistent with field or wind tunnel measurements. Therefore, a method was developed which allows the modelling of a horizontally homogeneous turbulence kinetic energy profile that is varying with height. By comparing simulations performed with the proposed method to simulations performed with the boundary conditions described by Richards and Hoxey (1993. Appropriate boundary conditions for computational wind engineering models using the k-ɛ turbulence model. Journal of Wind Engineering and Industrial Aerodynamics 46-47, 145-153.), the influence of the turbulence kinetic energy on the dispersion of small particles over flat terrain is quantified.
Giese, Daniel; Weiss, Kilian; Baeßler, Bettina; Madershahian, Navid; Choi, Yeong-Hoon; Maintz, David; Bunck, Alexander C
2017-09-18
The objective of the current work was to evaluate flow and turbulent kinetic energy in different transcatheter aortic valve implants using highly undersampled time-resolved multi-point 3-directional phase-contrast measurements (4D Flow MRI) in an in vitro setup. A pulsatile flow setup was used with a compliant tubing mimicking a stiff left ventricular outflow tract and ascending aorta. Five different implants were measured using a highly undersampled multi-point 4D Flow MRI sequence. Velocities and turbulent kinetic energy values were analysed and compared. Strong variations of turbulent kinetic energy distributions between the valves were observed. Maximum turbulent kinetic energy values ranged from 100 to over 500 J/m(3) while through-plane velocities were similar between all valves. Highly accelerated 4D Flow MRI for the measurement of velocities and turbulent kinetic energy values allowed for the assessment of hemodynamic parameters in five different implant models. The presented setup, measurement protocol and analysis methods provides an efficient approach to compare different valve implants and could aid future novel valve designs.
Nikitin, A V; Rey, M; Tyuterev, Vl G
2015-03-07
A simultaneous use of the full molecular symmetry and of an exact kinetic energy operator (KEO) is of key importance for accurate predictions of vibrational levels at a high energy range from a potential energy surface (PES). An efficient method that permits a fast convergence of variational calculations would allow iterative optimization of the PES parameters using experimental data. In this work, we propose such a method applied to tetrahedral AB4 molecules for which a use of high symmetry is crucial for vibrational calculations. A symmetry-adapted contracted angular basis set for six redundant angles is introduced. Simple formulas using this basis set for explicit calculation of the angular matrix elements of KEO and PES are reported. The symmetric form (six redundant angles) of vibrational KEO without the sin(q)(-2) type singularity is derived. The efficient recursive algorithm based on the tensorial formalism is used for the calculation of vibrational matrix elements. A good basis set convergence for the calculations of vibrational levels of the CH4 molecule is demonstrated.
Nikitin, A. V.; Rey, M.; Tyuterev, Vl. G.
2015-03-07
A simultaneous use of the full molecular symmetry and of an exact kinetic energy operator (KEO) is of key importance for accurate predictions of vibrational levels at a high energy range from a potential energy surface (PES). An efficient method that permits a fast convergence of variational calculations would allow iterative optimization of the PES parameters using experimental data. In this work, we propose such a method applied to tetrahedral AB{sub 4} molecules for which a use of high symmetry is crucial for vibrational calculations. A symmetry-adapted contracted angular basis set for six redundant angles is introduced. Simple formulas using this basis set for explicit calculation of the angular matrix elements of KEO and PES are reported. The symmetric form (six redundant angles) of vibrational KEO without the sin(q){sup −2} type singularity is derived. The efficient recursive algorithm based on the tensorial formalism is used for the calculation of vibrational matrix elements. A good basis set convergence for the calculations of vibrational levels of the CH{sub 4} molecule is demonstrated.
Zaccone, Alessio; Gentili, Daniele; Wu, Hua; Morbidelli, Massimo
2010-04-07
The aggregation of interacting brownian particles in sheared concentrated suspensions is an important issue in colloid and soft matter science per se. Also, it serves as a model to understand biochemical reactions occurring in vivo where both crowding and shear play an important role. We present an effective medium approach within the Smoluchowski equation with shear which allows one to calculate the encounter kinetics through a potential barrier under shear at arbitrary colloid concentrations. Experiments on a model colloidal system in simple shear flow support the validity of the model in the concentration range considered. By generalizing Kramers' rate theory to the presence of shear and collective hydrodynamics, our model explains the significant increase in the shear-induced reaction-limited aggregation kinetics upon increasing the colloid concentration.
NASA Astrophysics Data System (ADS)
Adamovic, D.; Münger, E. P.; Chirita, V.; Hultman, L.; Greene, J. E.
2005-05-01
Embedded-atom molecular dynamics simulations are used to investigate the effects of low-energy self-ion irradiation of Pt adatoms on Pt(111). Here, we concentrate on self-bombardment dynamics, i.e., isolating and monitoring the atomic processes, induced by normally incident Pt atoms with energies E ranging from 5 to 50 eV, that can affect intra- and interlayer mass transport.. We find that adatom scattering, surface channeling, and dimer formation occur at all energies. Atomic intermixing events involving incident and terrace atoms are observed at energies ⩾15eV, while the collateral formation of residual surface vacancies is observed only with E >40eV. The overall effect of low-energy self-ion irradiation is to enhance lateral adatom and terrace atom migration.
Karlsson, Johan; Atefyekta, Saba; Andersson, Martin
2015-01-01
The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding-diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments.
Kinetic selection vs. free energy of DNA base pairing in control of polymerase fidelity.
Oertell, Keriann; Harcourt, Emily M; Mohsen, Michael G; Petruska, John; Kool, Eric T; Goodman, Myron F
2016-04-19
What is the free energy source enabling high-fidelity DNA polymerases (pols) to favor incorporation of correct over incorrect base pairs by 10(3)- to 10(4)-fold, corresponding to free energy differences of ΔΔGinc∼ 5.5-7 kcal/mol? Standard ΔΔG° values (∼0.3 kcal/mol) calculated from melting temperature measurements comparing matched vs. mismatched base pairs at duplex DNA termini are far too low to explain pol accuracy. Earlier analyses suggested that pol active-site steric constraints can amplify DNA free energy differences at the transition state (kinetic selection). A recent paper [Olson et al. (2013)J Am Chem Soc135:1205-1208] used Vent pol to catalyze incorporations in the presence of inorganic pyrophosphate intended to equilibrate forward (polymerization) and backward (pyrophosphorolysis) reactions. A steady-state leveling off of incorporation profiles at long reaction times was interpreted as reaching equilibrium between polymerization and pyrophosphorolysis, yielding apparent ΔG° = -RTlnKeq, indicating ΔΔG° of 3.5-7 kcal/mol, sufficient to account for pol accuracy without need of kinetic selection. Here we perform experiments to measure and account for pyrophosphorolysis explicitly. We show that forward and reverse reactions attain steady states far from equilibrium for wrong incorporations such as G opposite T. Therefore,[Formula: see text]values obtained from such steady-state evaluations ofKeqare not dependent on DNA properties alone, but depend largely on constraints imposed on right and wrong substrates in the polymerase active site.
Karlsson, Johan; Atefyekta, Saba; Andersson, Martin
2015-01-01
The osseointegration capacity of bone-anchoring implants can be improved by the use of drugs that are administrated by an inbuilt drug delivery system. However, to attain superior control of drug delivery and to have the ability to administer drugs of varying size, including proteins, further material development of drug carriers is needed. Mesoporous materials have shown great potential in drug delivery applications to provide and maintain a drug concentration within the therapeutic window for the desired period of time. Moreover, drug delivery from coatings consisting of mesoporous titania has shown to be promising to improve healing of bone-anchoring implants. Here we report on how the delivery of an osteoporosis drug, alendronate, can be controlled by altering pore size and surface energy of mesoporous titania thin films. The pore size was varied from 3.4 nm to 7.2 nm by the use of different structure-directing templates and addition of a swelling agent. The surface energy was also altered by grafting dimethylsilane to the pore walls. The drug uptake and release profiles were monitored in situ using quartz crystal microbalance with dissipation (QCM-D) and it was shown that both pore size and surface energy had a profound effect on both the adsorption and release kinetics of alendronate. The QCM-D data provided evidence that the drug delivery from mesoporous titania films is controlled by a binding–diffusion mechanism. The yielded knowledge of release kinetics is crucial in order to improve the in vivo tissue response associated to therapeutic treatments. PMID:26185444
Isospin quartic term in the kinetic energy of neutron-rich nucleonic matter
NASA Astrophysics Data System (ADS)
Cai, Bao-Jun; Li, Bao-An
2015-07-01
The energy of a free gas of neutrons and protons is well known to be approximately isospin parabolic with a negligibly small quartic term of only 0.45 MeV at the saturation density of nuclear matter ρ0=0.16 fm-3 . Using an isospin-dependent single-nucleon momentum distribution including a high (low) momentum tail (depletion) with its shape parameters constrained by recent high-energy electron scattering and medium-energy nuclear photodisintegration experiments as well as the state-of-the-art calculations of the deuteron wave function and the equation of state of pure neutron matter near the unitary limit within several modern microscopic many-body theories, we show for the first time that the kinetic energy of interacting nucleons in neutron-rich nucleonic matter has a significant quartic term of 7.18 ±2.52 MeV. Such a large quartic term has broad ramifications in determining the equation of state of neutron-rich nucleonic matter using observables of nuclear reactions and neutron stars.
Proton transfer pathways, energy landscape, and kinetics in creatine-water systems.
Ivchenko, Olga; Whittleston, Chris S; Carr, Joanne M; Imhof, Petra; Goerke, Steffen; Bachert, Peter; Wales, David J
2014-02-27
We study the exchange processes of the metabolite creatine, which is present in both tumorous and normal tissues and has NH2 and NH groups that can transfer protons to water. Creatine produces chemical exchange saturation transfer (CEST) contrast in magnetic resonance imaging (MRI). The proton transfer pathway from zwitterionic creatine to water is examined using a kinetic transition network constructed from the discrete path sampling approach and an approximate quantum-chemical energy function, employing the self-consistent-charge density-functional tight-binding (SCC-DFTB) method. The resulting potential energy surface is visualized by constructing disconnectivity graphs. The energy landscape consists of two distinct regions corresponding to the zwitterionic creatine structures and deprotonated creatine. The activation energy that characterizes the proton transfer from the creatine NH2 group to water was determined from an Arrhenius fit of rate constants as a function of temperature, obtained from harmonic transition state theory. The result is in reasonable agreement with values obtained in water exchange spectroscopy (WEX) experiments.
Kinetic model for the vibrational energy exchange in flowing molecular gas mixtures. Ph.D. Thesis
NASA Technical Reports Server (NTRS)
Offenhaeuser, F.
1987-01-01
The present study is concerned with the development of a computational model for the description of the vibrational energy exchange in flowing gas mixtures, taking into account a given number of energy levels for each vibrational degree of freedom. It is possible to select an arbitrary number of energy levels. The presented model uses values in the range from 10 to approximately 40. The distribution of energy with respect to these levels can differ from the equilibrium distribution. The kinetic model developed can be employed for arbitrary gaseous mixtures with an arbitrary number of vibrational degrees of freedom for each type of gas. The application of the model to CO2-H2ON2-O2-He mixtures is discussed. The obtained relations can be utilized in a study of the suitability of radiation-related transitional processes, involving the CO2 molecule, for laser applications. It is found that the computational results provided by the model agree very well with experimental data obtained for a CO2 laser. Possibilities for the activation of a 16-micron and 14-micron laser are considered.
Schmidt, Michael W; Ivanic, Joseph; Ruedenberg, Klaus
2014-05-28
An analysis based on the variation principle shows that in the molecules H2 (+), H2, B2, C2, N2, O2, F2, covalent bonding is driven by the attenuation of the kinetic energy that results from the delocalization of the electronic wave function. For molecular geometries around the equilibrium distance, two features of the wave function contribute to this delocalization: (i) Superposition of atomic orbitals extends the electronic wave function from one atom to two or more atoms; (ii) intra-atomic contraction of the atomic orbitals further increases the inter-atomic delocalization. The inter-atomic kinetic energy lowering that (perhaps counter-intuitively) is a consequence of the intra-atomic contractions drives these contractions (which per se would increase the energy). Since the contractions necessarily encompass both, the intra-atomic kinetic and potential energy changes (which add to a positive total), the fact that the intra-atomic potential energy change renders the total potential binding energy negative does not alter the fact that it is the kinetic delocalization energy that drives the bond formation.
Schmidt, Michael W; Ivanic, Joseph; Ruedenberg, Klaus
2014-05-28
An analysis based on the variation principle shows that in the molecules H2 +, H2, B2, C2, N2, O2, F2, covalent bonding is driven by the attenuation of the kinetic energy that results from the delocalization of the electronic wave function. For molecular geometries around the equilibrium distance, two features of the wave function contribute to this delocalization: (i) Superposition of atomic orbitals extends the electronic wave function from one atom to two or more atoms; (ii) intra-atomic contraction of the atomic orbitals further increases the inter-atomic delocalization. The inter-atomic kinetic energy lowering that (perhaps counter-intuitively) is a consequence of the intra-atomic contractions drives these contractions (which per se would increase the energy). Since the contractions necessarily encompass both, the intra-atomic kinetic and potential energy changes (which add to a positive total), the fact that the intra-atomic potential energy change renders the total potential binding energy negative does not alter the fact that it is the kinetic delocalization energy that drives the bond formation.
Schmidt, Michael W.; Ruedenberg, Klaus; Ivanic, Joseph
2014-05-28
An analysis based on the variation principle shows that in the molecules H{sub 2}{sup +}, H{sub 2}, B{sub 2}, C{sub 2}, N{sub 2}, O{sub 2}, F{sub 2}, covalent bonding is driven by the attenuation of the kinetic energy that results from the delocalization of the electronic wave function. For molecular geometries around the equilibrium distance, two features of the wave function contribute to this delocalization: (i) Superposition of atomic orbitals extends the electronic wave function from one atom to two or more atoms; (ii) intra-atomic contraction of the atomic orbitals further increases the inter-atomic delocalization. The inter-atomic kinetic energy lowering that (perhaps counter-intuitively) is a consequence of the intra-atomic contractions drives these contractions (which per se would increase the energy). Since the contractions necessarily encompass both, the intra-atomic kinetic and potential energy changes (which add to a positive total), the fact that the intra-atomic potential energy change renders the total potential binding energy negative does not alter the fact that it is the kinetic delocalization energy that drives the bond formation.
Schmidt, Michael W.; Ivanic, Joseph; Ruedenberg, Klaus
2014-01-01
An analysis based on the variation principle shows that in the molecules H2+, H2, B2, C2, N2, O2, F2, covalent bonding is driven by the attenuation of the kinetic energy that results from the delocalization of the electronic wave function. For molecular geometries around the equilibrium distance, two features of the wave function contribute to this delocalization: (i) Superposition of atomic orbitals extends the electronic wave function from one atom to two or more atoms; (ii) intra-atomic contraction of the atomic orbitals further increases the inter-atomic delocalization. The inter-atomic kinetic energy lowering that (perhaps counter-intuitively) is a consequence of the intra-atomic contractions drives these contractions (which per se would increase the energy). Since the contractions necessarily encompass both, the intra-atomic kinetic and potential energy changes (which add to a positive total), the fact that the intra-atomic potential energy change renders the total potential binding energy negative does not alter the fact that it is the kinetic delocalization energy that drives the bond formation. PMID:24880263
Estimation of Rainfall Kinetic Energy by Rain Intensity and/or Radar Reflectivity Factor
NASA Astrophysics Data System (ADS)
Yu, N.; Delrieu, G.; Boudevillain, B.; Hazenberg, P.; Uijlenhoet, R.
2011-12-01
This study presents an approach to estimate the rainfall kinetic energy (KE) by rain intensity (R) and radar reflectivity factor (Z) separately, or jointly, on the basis of a one- or two-moment scaled formulation. This formulation considers the raindrop size distribution (DSD) as a combination of bulk rainfall variable(s) (R or/and Z) and an intrinsic distribution g(x), which is in function of the scaled raindrop diameter x. Results from previous studies showed that g(x) remains more or less constant, hence the variability of DSD is mainly explained by the bulk rainfall variable(s). In this study, the Gamma probability density function (pdf) with two parameters is used to model the g(x). Considered the self-consistent relationships between parameters, a robust method is proposed to estimate three climatological g(x), in R-, Z- and RZ-scaled formulation respectively, with a 28-month DSD dataset collected in the Cevennes-Vivarais region, France. Three relationships (KE-R, KE-Z and KE-(R,Z)), which link the observations (R and/or Z) to rainfall kinetic energy (KE), are established based on three climatological g(x). As expected, the combination of R and Z yields a significant improvement of the estimation of KE compared to the single-moment formulations. And Z yields a better performance in KE estimating compared to the KE-R relationship. In terms of the application of these relationships based on real radar reflectivity factors and/or rain gauge measurements, the combination of R and Z yields also the best performance in estimation of KE among the three relationships. Different from the application of the disdrometer data, the performance of the real KE-Z relationship degrades compared to the real KE-R relationship, which is probably due to the sampling error of radar. However, KE estimated by radar possess the advantages in spatialization of kinetic energy over that based on rain gauge stations. This study was supported financially by the HYDRATE project of the
NASA Astrophysics Data System (ADS)
Uzdensky, Dmitri
Relativistic astrophysical plasma environments routinely produce intense high-energy emission, which is often observed to be nonthermal and rapidly flaring. The recently discovered gamma-ray (> 100 MeV) flares in Crab Pulsar Wind Nebula (PWN) provide a quintessential illustration of this, but other notable examples include relativistic active galactic nuclei (AGN) jets, including blazars, and Gamma-ray Bursts (GRBs). Understanding the processes responsible for the very efficient and rapid relativistic particle acceleration and subsequent emission that occurs in these sources poses a strong challenge to modern high-energy astrophysics, especially in light of the necessity to overcome radiation reaction during the acceleration process. Magnetic reconnection and collisionless shocks have been invoked as possible mechanisms. However, the inferred extreme particle acceleration requires the presence of coherent electric-field structures. How such large-scale accelerating structures (such as reconnecting current sheets) can spontaneously arise in turbulent astrophysical environments still remains a mystery. The proposed project will conduct a first-principles computational and theoretical study of kinetic turbulence in relativistic collisionless plasmas with a special focus on nonthermal particle acceleration and radiation emission. The main computational tool employed in this study will be the relativistic radiative particle-in-cell (PIC) code Zeltron, developed by the team members at the Univ. of Colorado. This code has a unique capability to self-consistently include the synchrotron and inverse-Compton radiation reaction force on the relativistic particles, while simultaneously computing the resulting observable radiative signatures. This proposal envisions performing massively parallel, large-scale three-dimensional simulations of driven and decaying kinetic turbulence in physical regimes relevant to real astrophysical systems (such as the Crab PWN), including the
Kinetics of the cellular intake of a gene expression inducer at high concentrations.
Tran, Huy; Oliveira, Samuel M D; Goncalves, Nadia; Ribeiro, Andre S
2015-09-01
From in vivo single-event measurements of the transient and steady-state transcription activity of a single-copy lac-ara-1 promoter in Escherichia coli, we characterize the intake kinetics of its inducer (IPTG) from the media. We show that the empirical data are well-fit by a model of intake assuming a bilayer membrane, with the passage through the second layer being rate-limiting, coupled to a stochastic, sub-Poissonian, multi-step transcription process. Using this model, we show that for a wide range of extracellular inducer levels (up to 1.25 mM) the intake process is diffusive-like, suggesting unsaturated membrane permeability. Inducer molecules travel from the periplasm to the cytoplasm in, on average, 31.7 minutes, strongly affecting cells' response time. The novel methodology followed here should aid the study of cellular intake mechanisms at the single-event level.
A subsynoptic-scale kinetic energy study of the Red River Valley tornado outbreak (AVE-SESAME 1)
NASA Technical Reports Server (NTRS)
Jedlovec, G. J.; Fuelberg, H. E.
1981-01-01
The subsynoptis-scale kinetic energy balance during the Red River Valley tornado outbreak is presented in order to diagnose storm environment interactions. Area-time averaged energetics indicate that horizontal flux convergence provides the major energy source to the region, while cross contour flow provides the greatest sink. Maximum energy variability is found in the upper levels in association with jet stream activity. Area averaged energetics at individual observation times show that the energy balance near times of maximum storm activity differs considerably from that of the remaining periods. The local kinetic energy balance over Oklahoma during the formation of a limited jet streak receives special attention. Cross contour production of energy is the dominant local source for jet development. Intense convection producing the Red River Valley tornadoes may have contributed to this local development by modifying the surrounding environment.
Inversion vibration of PH3+(X~ 2A2'') studied by zero kinetic energy photoelectron spectroscopy
NASA Astrophysics Data System (ADS)
Yang, Jie; Li, Juan; Hao, Yusong; Zhou, Chang; Mo, Yuxiang
2006-08-01
We report the first rotationally resolved spectroscopic studies on PH3+(X˜A2″2) using zero kinetic energy photoelectron spectroscopy and coherent VUV radiation. The spectra about 8000cm-1 above the ground vibrational state of PH3+(X˜A2″2) have been recorded. We observed the vibrational energy level splittings of PH3+(X˜A2″2) due to the tunneling effect in the inversion (symmetric bending) vibration (ν2+). The energy splitting for the first inversion vibrational state (0+/0-) is 5.8cm-1. The inversion vibrational energy levels, rotational constants, and adiabatic ionization energies (IEs) for ν2+=0-16 have been determined. The bond angles between the neighboring P-H bonds and the P-H bond lengths are also obtained using the experimentally determined rotational constants. With the increasing of the inversion vibrational excitations (ν2+), the bond lengths (P-H) increase a little and the bond angles (H-P-H) decrease a lot. The inversion vibrational energy levels have also been calculated by using one dimensional potential model and the results are in good agreement with the experimental data for the first several vibrational levels. In addition to inversion vibration, we also observed firstly the other two vibrational modes: the symmetric P-H stretching vibration (ν1+) and the degenerate bending vibration (ν4+). The fundamental frequencies for ν1+ and ν4+ are 2461.6 (±2) and 1043.9 (±2)cm-1, respectively. The first IE for PH3 was determined as 79670.9 (±1)cm-1.
Hybrid Kinetic-Fluid Electromagnetic Simulations of Imploding High Energy Density Plasmas for IFE
NASA Astrophysics Data System (ADS)
Welch, Dale; Rose, Dave; Thoma, Carsten; Genoni, Thomas; Bruner, Nichelle; Clark, Robert; Stygar, William; Leeper, Ramon
2011-10-01
A new simulation technique is being developed to study high current and moderate density-radius product (ρR) z-pinch plasmas relevant to Inertial Fusion Energy (IFE). Fully kinetic, collisional, and electromagnetic simulations of the time evolution of up to 40-MA current (deuterium and DT) z-pinches, but with relatively low ρR, have yielded new insights into the mechanisms of neutron production. At fusion relevant conditions (ρR > 0.01 gm/cm2) , however, this technique requires a prohibitively large number of cells and particles. A new hybrid implicit technique has been developed that accurately describes high-density and magnetized imploding plasmas. The technique adapts a recently published algorithm, that enables accurate descriptions of highly magnetized particle orbits, to high density plasmas and also makes use of an improved kinetic particle remap technique. We will discuss the new technique, stable range of operation, and application to an IFE relevant z-pinch design at 60 MA. Work supported by Sandia National Laboratories.
NASA Astrophysics Data System (ADS)
Appannababu, S.; Cinausero, M.; Marchi, T.; Gramegna, F.; Prete, G.; Bermudez, J.; Fabris, D.; Collazuol, G.; Saxena, A.; Nayak, B. K.; Kailas, S.; Bruno, M.; Morelli, L.; Gelli, N.; Piantelli, S.; Pasquali, G.; Barlini, S.; Valdré, S.; Vardaci, E.; Sajo-Bohus, L.; Degerlier, M.; Jhingan, A.; Behera, B. R.; Kravchuk, V. L.
2016-10-01
The correlations between mass distributions of the binary fragments, total kinetic energy (TKE), and neutron multiplicity have been investigated for the reaction +208Pb 50Ti at 294 MeV bombarding energy. Although this reaction has been used to synthesize the Rf (Z =104 ) superheavy element, a complete study of its fragmentation dynamics is still not available in the literature. In this work, average neutron multiplicities were extracted as a function of different fragment mass splits and TKE windows. A weak increase of the prescission neutron multiplicity is observed going from asymmetric to symmetric mass splits. A fission delay time of 4.5 ×10-20 s has been extracted for the symmetric fission. The neutron multiplicity extracted for the symmetric mass split was used to derive the average number of neutrons emitted in the spontaneous fission of 258Rf. The extrapolated value of 4.7 ±1.4 is found to be consistent with systematics of spontaneous and neutron-induced fission in heavy nuclei and with the results of previous works for superheavy nuclei with Z =116 and Z =124 .
NASA Technical Reports Server (NTRS)
Chen, T.-C.; Alpert, J. C.; Schlatter, T. W.
1978-01-01
The magnitude of the divergent component of the wind is relatively small compared to that of the nondivergent component in large-scale atmospheric flows; nevertheless, it plays an important role in the case of explosive cyclogenesis examined here. The kinetic energy budget for the life cycle of an intense, developing cyclone over North America is calculated. The principal kinetic energy source is the net horizontal transport across the boundaries of the region enclosing the cyclone. By investigating the relative importance of the divergent and nondivergent wind components in the kinetic energy budget, it was found, as expected, that neglecting the divergent wind component in calculating the magnitude of the kinetic energy is of little consequence, but that the horizontal flux convergence and generation of kinetic energy depend crucially upon the divergent component. Modification of the divergent wind component can result in significant changes in the kinetic energy budget of the synoptic system.
NASA Technical Reports Server (NTRS)
Chen, T.-C.; Alpert, J. C.; Schlatter, T. W.
1978-01-01
The magnitude of the divergent component of the wind is relatively small compared to that of the nondivergent component in large-scale atmospheric flows; nevertheless, it plays an important role in the case of explosive cyclogenesis examined here. The kinetic energy budget for the life cycle of an intense, developing cyclone over North America is calculated. The principal kinetic energy source is the net horizontal transport across the boundaries of the region enclosing the cyclone. By investigating the relative importance of the divergent and nondivergent wind components in the kinetic energy budget, it was found, as expected, that neglecting the divergent wind component in calculating the magnitude of the kinetic energy is of little consequence, but that the horizontal flux convergence and generation of kinetic energy depend crucially upon the divergent component. Modification of the divergent wind component can result in significant changes in the kinetic energy budget of the synoptic system.
NASA Astrophysics Data System (ADS)
N'tsouaglo, Kokou; Joly, Jean-Francois; Beland, Laurent; Brommer, Peter; Mousseau, Normand
2013-03-01
In the last two decades, there has been a considerable interest in the development of accelerated numerical methods for sampling the energy landscape of complex materials. Many of these methods are based on the kinetic Monte Carlo (KMC) algorithm introduced 40 years ago. This is the case of kinetic ART, for example, which uses a very efficient transition-state searching method, ART nouveau, coupled with a topological tool, NAUTY, to offer an off-lattice KMC method with on-the-fly catalog building to study complex systems, such as ion-bombarded and amorphous materials, on timescales of a second or more. Looking at two systems, vacancy aggregation in Fe and energy relaxation in ion-bombarded c-Si, we characterize the changes in the energy landscape and the relation to its time evolution with kinetic ART and its correspondence with the well-known Bell-Evans-Polanyi principle used in chemistry.
Ohkubo, T. Ishii, Y.
2015-03-15
A compact focused gaseous ion beam system has been developed to form proton microbeams of a few hundreds of keV with a penetration depth of micrometer range in 3-dimensional proton beam writing. Proton microbeams with kinetic energies of 100-140 keV were experimentally formed on the same point at a constant ratio of the kinetic energy of the object side to that of the image side. The experimental results indicate that the beam diameters were measured to be almost constant at approximately 6 μm at the same point with the kinetic energy range. These characteristics of the system were experimentally and numerically demonstrated to be maintained as long as the ratio was constant.
Impact of Various Processes on the Transient Evolution of Spectral Kinetic Energies.
NASA Astrophysics Data System (ADS)
Schilling, Heinz-Dieter
1990-08-01
Geopotential height fields for nine winters (1967/68-1975/76) and summers on three levels (300, 500, 1000 mb), provided by the German Weather Service, are used to compute daily budgets of kinetic energy (Km) for single zonal wavenumbers m within a quasi-geostrophic framework. The energetics are averaged over the depth of the troposphere and the latitudinal belt 40°N 85°N.Inadequate field resolution by data, and inevitable model approximations justify regressive corrections of the energy conversion estimates, leading to upper-bound estimates of the fraction of kinetic energy variance explained by different conversions (hindcast skills). The results are(i) Persistence is most important for the evolution of Km for m 4; the skill ranges from 76% to 59% (in winter). The importance is less for m 5, according to the skills ranging from 51% to 43% (in winter).(ii) For 1 m 4 the sum of energy conversions explains approximately 35%-45% of the variance of Km, left unexplained by persistence in winter. In this wave range the leading process is the nonlinear interaction with waves m 5, whereas conversions between Kz and Km as well as lateral boundary fluxes are of the least importance. The evolution of Km for m = 2,,4 is unexpectedly well correlated to the conversion between available potential energies C(AzAm) which appears to be a good substitute for C(AmKm), which is proportional to the vertical sensible heatflux.(iii) For waves with 5 m 8 the sum of conversions explains 30%-50% of the variance of Km, left unexplained by persistence in winter.The baroclinic conversion C(AmKm) contributes the largest skill; however, C(AzAm) is a better indicator of baroclinic activity even in this wave range. The next largest impact on Km stems from nonlinear wave- wave interactions involving at least one other short wave with m = 6,,12. The influence of C(KzKm) is insignificant in the wave range 5 m
Exact numerical computation of a kinetic energy operator in curvilinear coordinates
NASA Astrophysics Data System (ADS)
Lauvergnat, David; Nauts, André
2002-05-01
The conformation and dynamical behavior of molecular systems is very often advantageously described in terms of physically well-adapted curvilinear coordinates. It is rather easy to show that the numerous analytical expressions of the kinetic energy operator of a molecular system described in terms of n curvilinear coordinates can all be transformed into the following more usable expression: T̂=∑ijf2ij(q)∂2/∂qi∂qj+∑if1i(q)∂/∂qi+ν(q), where f2ij(q), f1i(q), and ν(q) are functions of the curvilinear coordinates q=(…,qi,…). If the advantages of curvilinear coordinates are unquestionable, they do have a major drawback: the sometimes awful complexity of the analytical expression of the kinetic operator T̂ for molecular systems with more than five atoms. Therefore, we develop an algorithm for computing T̂ for a given value of the n curvilinear coordinates q. The calculation of the functions f2ij(q), f1i(q), and ν(q) only requires the knowledge of the Cartesian coordinates and their derivatives in terms of the n curvilinear coordinates. This coordinate transformation (curvilinear→Cartesian) is very easy to perform and is widely used in quantum chemistry codes resorting to a Z-matrix to define the curvilinear coordinates. Thus, the functions f2ij(q), f1i(q), and ν(q) can be evaluated numerically and exactly for a given value of q, which makes it possible to propagate wavepackets or to simulate the spectra of rather complex systems (constrained Hamiltonian). The accuracy of this numerical procedure is tested by comparing two calculations of the bending spectrum of HCN: the first one, performed by using the present numerical kinetic operator procedure, the second one, obtained in previous studies, by using an analytical kinetic operator. Finally, the ab initio computation of the internal rotation spectrum and wave functions of 2-methylpropanal by means of dimensionality reduction, is given as an original application.
NASA Astrophysics Data System (ADS)
Gadre, Shridhar R.; Bendale, Rajeev D.
1987-08-01
An uncertainty-type lower bound [I. Bialynicki-Birula and J. Mycielski, Commun. Math. Phys. 44, 129 (1975)] to the information-entropy sum in complementary spaces has recently been reformulated by Gadre et al. [Phys. Rev. A 32, 2602 (1985)] in terms of the respective one-particle probability densities. This bound has been exploited to derive rigorous upper as well as lower bounds to the information entropies and their sum in terms of the corresponding second moments of their distributions. Thus the present work establishes a direct connection, as suggested by Sears, Parr, and Dinur [Israel J. Chem. 19, 165 (1980)], between the quantum-mechanical kinetic energy and information entropy in position space. It has also been demonstrated that given at least one arbitrary moment-type constraint in each space, it is possible to derive an upper bound to the information entropy sum in complementary spaces.
Seasonal variability of eddy kinetic energy in a global high-resolution ocean model
NASA Astrophysics Data System (ADS)
Rieck, Jan K.; Böning, Claus W.; Greatbatch, Richard J.; Scheinert, Markus
2015-11-01
A global ocean model with 1/12° horizontal resolution is used to assess the seasonal cycle of surface eddy kinetic energy (EKE). The model reproduces the salient features of the observed mean surface EKE, including amplitude and phase of its seasonal cycle in most parts of the ocean. In all subtropical gyres of the Pacific and Atlantic, EKE peaks in summer down to a depth of ˜350 m, below which the seasonal cycle is weak. Investigation of the possible driving mechanisms reveals the seasonal changes in the thermal interactions with the atmosphere to be the most likely cause of the summer maximum of EKE. The development of the seasonal thermocline in spring and summer is accompanied by stronger mesoscale variations in the horizontal temperature gradients near the surface which corresponds, by thermal wind balance, to an intensification of mesoscale velocity anomalies toward the surface.
Energy resolution and efficiency of phonon-mediated kinetic inductance detectors for light detection
NASA Astrophysics Data System (ADS)
Cardani, L.; Colantoni, I.; Cruciani, A.; Di Domizio, S.; Vignati, M.; Bellini, F.; Casali, N.; Castellano, M. G.; Coppolecchia, A.; Cosmelli, C.; Tomei, C.
2015-08-01
The development of sensitive cryogenic light detectors is of primary interest for bolometric experiments searching for rare events like dark matter interactions or neutrino-less double beta decay. Thanks to their good energy resolution and the natural multiplexed read-out, Kinetic Inductance Detectors (KIDs) are particularly suitable for this purpose. To efficiently couple KIDs-based light detectors to the large crystals used by the most advanced bolometric detectors, active surfaces of several cm2 are needed. For this reason, we are developing phonon-mediated detectors. In this paper, we present the results obtained with a prototype consisting of four 40 nm thick aluminum resonators patterned on a 2 × 2 cm2 silicon chip, and calibrated with optical pulses and X-rays. The detector features a noise resolution σE = 154 ± 7 eV and an (18 ± 2)% efficiency.
NASA Astrophysics Data System (ADS)
Zilletti, Michele; Gardonio, Paolo; Elliott, Stephen J.
2014-09-01
In this study the active vibration control of a structure modelled as a single degree of freedom system and excited by a white noise force is considered. The control system consists of an inertial actuator driven with a signal proportional to the velocity of the structure under control measured by an ideal collocated sensor. The optimisation of the physical and control parameters of the control system such as the internal damping of the actuator, its natural frequency and the feedback gain of the controller are considered such that either the kinetic energy of the host structure is minimised or the power dissipated by the control system is maximised. This type of control system is only conditionally stable therefore a stability condition has to be satisfied by the optimisation process. The paper shows that the two optimisation criteria are equivalent.