Correlation between Geometrically Induced Oxygen Octahedral Tilts and Multiferroic Behaviors in BiFeO 3 Films

DOE PAGES

Lee, Sung Su; Kim, Young-Min; Lee, Hyun-Jae; ...

2018-03-26

The equilibrium position of atoms in a unit cell is directly connected to crystal functionalities, e.g., ferroelectricity, ferromagnetism, and piezoelectricity. The artificial tuning of the energy landscape can involve repositioning atoms as well as manipulating the functionalities of perovskites (ABO 3), which are good model systems to test this legacy. Mechanical energy from external sources accommodating various clamping substrates is utilized to perturb the energy state of perovskite materials fabricated on the substrates and consequently change their functionalities; however, this approach yields undesired complex behaviors of perovskite crystals, such as lattice distortion, displacement of B atoms, and/or tilting of oxygenmore » octahedra. Owing to complimentary collaborations between experimental and theoretical studies, the effects of both lattice distortion and displacement of B atoms are well understood so far, which leaves us a simple question: Can we exclusively control the positions of oxygen atoms in perovskites for functionality manipulation? Here the artificial manipulation of oxygen octahedral tilt angles within multiferroic BiFeO 3 thin films using strong oxygen octahedral coupling with bottom SrRuO 3 layers is reported, which opens up new possibilities of oxygen octahedral engineering.« less

Bistability and displacement fluctuations in a quantum nanomechanical oscillator

NASA Astrophysics Data System (ADS)

Avriller, R.; Murr, B.; Pistolesi, F.

2018-04-01

Remarkable features have been predicted for the mechanical fluctuations at the bistability transition of a classical oscillator coupled capacitively to a quantum dot [Micchi et al., Phys. Rev. Lett. 115, 206802 (2015), 10.1103/PhysRevLett.115.206802]. These results have been obtained in the regime ℏ ω0≪kBT ≪ℏ Γ , where ω0, T , and Γ are the mechanical resonating frequency, the temperature, and the tunneling rate, respectively. A similar behavior could be expected in the quantum regime of ℏ Γ ≪kBT ≪ℏ ω0 . We thus calculate the energy- and displacement-fluctuation spectra and study their behavior as a function of the electromechanical coupling constant when the system enters the Frank-Condon regime. We find that in analogy with the classical case, the energy-fluctuation spectrum and the displacement spectrum widths show a maximum for values of the coupling constant at which a mechanical bistability is established.

Efficiency of SparkJet

NASA Technical Reports Server (NTRS)

Golbabaei-Asl, M.; Knight, D.; Wilkinson, S.

2013-01-01

The thermal efficiency of a SparkJet is evaluated by measuring the impulse response of a pendulum subject to a single spark discharge. The SparkJet is attached to the end of a pendulum. A laser displacement sensor is used to measure the displacement of the pendulum upon discharge. The pendulum motion is a function of the fraction of the discharge energy that is channeled into the heating of the gas (i.e., increasing the translational-rotational temperature). A theoretical perfect gas model is used to estimate the portion of the energy from the heated gas that results in equivalent pendulum displacement as in the experiment. The earlier results from multiple runs for different capacitances of C = 3, 5, 10, 20, and 40(micro)F demonstrate that the thermal efficiency decreases with higher capacitive discharges.1 In the current paper, results from additional run cases have been included and confirm the previous results

Energy dissipation in a friction-controlled slide of a body excited by random motions of the foundation

NASA Astrophysics Data System (ADS)

Berezin, Sergey; Zayats, Oleg

2018-01-01

We study a friction-controlled slide of a body excited by random motions of the foundation it is placed on. Specifically, we are interested in such quantities as displacement, traveled distance, and energy loss due to friction. We assume that the random excitation is switched off at some time (possibly infinite) and show that the problem can be treated in an analytic, explicit, manner. Particularly, we derive formulas for the moments of the displacement and distance, and also for the average energy loss. To accomplish that we use the Pugachev-Sveshnikov equation for the characteristic function of a continuous random process given by a system of SDEs. This equation is solved by reduction to a parametric Riemann boundary value problem of complex analysis.

Cascade morphology transition in bcc metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Selby, A.; Juslin, Niklas

2015-06-10

Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent,more » $b$, in the defect production curve as a function of cascade energy ($$N_F$$$ \\sim$$$E_{MD}^b$$). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, $$\\mu$$, between the high- and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of $$\\mu$$ as a function of displacement threshold energy, $$E_d$$, is presented for bcc metals.« less

Cascade morphology transition in bcc metals

DOE PAGES

Setyawan, Wahyu; Selby, Aaron P.; Juslin, Niklas; ...

2015-05-18

Energetic atom collisions in solids induce shockwaves with complex morphologies. In this paper, we establish the existence of a morphological transition in such cascades. The order parameter of the morphology is defined as the exponent, b, in the defect production curve as a function of cascade energy (N-F similar to E-MD(b)). Response of different bcc metals can be compared in a consistent energy domain when the energy is normalized by the transition energy, mu, between the high-and the low-energy regime. Using Cr, Fe, Mo and W data, an empirical formula of mu as a function of displacement threshold energy, E-d,more » is presented for bcc metals.« less

Surgical and functional outcomes after operative management of complex and displaced intra-articular glenoid fractures.

PubMed

Anavian, Jack; Gauger, Erich M; Schroder, Lisa K; Wijdicks, Coen A; Cole, Peter A

2012-04-04

Operative treatment is indicated for displaced fractures of the glenoid fossa. However, little is known regarding functional outcomes in these patients. This study assesses surgical and functional results after treatment of displaced, high-energy, complex, intra-articular glenoid fractures. Thirty-three patients with displaced intra-articular fractures of the glenoid were treated surgically between 2002 and 2009. The indications for operative treatment included articular fracture gap or step-off of ≥ 4 mm. Twenty-five patients also had extra-articular scapular involvement. A posterior approach was utilized in twenty-one patients, an anterior approach in seven, and a combined approach in five. Functional outcomes, including Disabilities of the Arm, Shoulder and Hand (DASH) and Short Form-36 (SF-36) scores, shoulder motion and strength, and return to work and/or activities, were obtained for thirty patients (91%). At a mean follow-up of twenty-seven months (range, twelve to seventy-three months), all patients had radiographic union of the fracture. The mean DASH score was 10.8 (range, 0 to 42). All mean SF-36 subscores were comparable with those of the normal population. Twenty-six patients (87%) were pain-free at the time of follow-up, and four had mild pain with prolonged activity. Twenty-seven (90%) of thirty patients returned to their preinjury level of work and/or activities. Our data suggest that surgical treatment for complex, displaced intra-articular glenoid fractures with or without involvement of the scapular neck and body can be associated with good functional outcomes and a low complication rate.

Discrete wavelet transform: a tool in smoothing kinematic data.

PubMed

Ismail, A R; Asfour, S S

1999-03-01

Motion analysis systems typically introduce noise to the displacement data recorded. Butterworth digital filters have been used to smooth the displacement data in order to obtain smoothed velocities and accelerations. However, this technique does not yield satisfactory results, especially when dealing with complex kinematic motions that occupy the low- and high-frequency bands. The use of the discrete wavelet transform, as an alternative to digital filters, is presented in this paper. The transform passes the original signal through two complementary low- and high-pass FIR filters and decomposes the signal into an approximation function and a detail function. Further decomposition of the signal results in transforming the signal into a hierarchy set of orthogonal approximation and detail functions. A reverse process is employed to perfectly reconstruct the signal (inverse transform) back from its approximation and detail functions. The discrete wavelet transform was applied to the displacement data recorded by Pezzack et al., 1977. The smoothed displacement data were twice differentiated and compared to Pezzack et al.'s acceleration data in order to choose the most appropriate filter coefficients and decomposition level on the basis of maximizing the percentage of retained energy (PRE) and minimizing the root mean square error (RMSE). Daubechies wavelet of the fourth order (Db4) at the second decomposition level showed better results than both the biorthogonal and Coiflet wavelets (PRE = 97.5%, RMSE = 4.7 rad s-2). The Db4 wavelet was then used to compress complex displacement data obtained from a noisy mathematically generated function. Results clearly indicate superiority of this new smoothing approach over traditional filters.

Validation of experimental molecular crystal structures with dispersion-corrected density functional theory calculations.

PubMed

van de Streek, Jacco; Neumann, Marcus A

2010-10-01

This paper describes the validation of a dispersion-corrected density functional theory (d-DFT) method for the purpose of assessing the correctness of experimental organic crystal structures and enhancing the information content of purely experimental data. 241 experimental organic crystal structures from the August 2008 issue of Acta Cryst. Section E were energy-minimized in full, including unit-cell parameters. The differences between the experimental and the minimized crystal structures were subjected to statistical analysis. The r.m.s. Cartesian displacement excluding H atoms upon energy minimization with flexible unit-cell parameters is selected as a pertinent indicator of the correctness of a crystal structure. All 241 experimental crystal structures are reproduced very well: the average r.m.s. Cartesian displacement for the 241 crystal structures, including 16 disordered structures, is only 0.095 Å (0.084 Å for the 225 ordered structures). R.m.s. Cartesian displacements above 0.25 A either indicate incorrect experimental crystal structures or reveal interesting structural features such as exceptionally large temperature effects, incorrectly modelled disorder or symmetry breaking H atoms. After validation, the method is applied to nine examples that are known to be ambiguous or subtly incorrect.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Weizhou, E-mail: wzw@lynu.edu.cn, E-mail: ybw@gzu.edu.cn; Zhang, Yu; Sun, Tao

High-level coupled cluster singles, doubles, and perturbative triples [CCSD(T)] computations with up to the aug-cc-pVQZ basis set (1924 basis functions) and various extrapolations toward the complete basis set (CBS) limit are presented for the sandwich, T-shaped, and parallel-displaced benzene⋯naphthalene complex. Using the CCSD(T)/CBS interaction energies as a benchmark, the performance of some newly developed wave function and density functional theory methods has been evaluated. The best performing methods were found to be the dispersion-corrected PBE0 functional (PBE0-D3) and spin-component scaled zeroth-order symmetry-adapted perturbation theory (SCS-SAPT0). The success of SCS-SAPT0 is very encouraging because it provides one method for energy componentmore » analysis of π-stacked complexes with 200 atoms or more. Most newly developed methods do, however, overestimate the interaction energies. The results of energy component analysis show that interaction energies are overestimated mainly due to the overestimation of dispersion energy.« less

Rupture models with dynamically determined breakdown displacement

USGS Publications Warehouse

Andrews, D.J.

2004-01-01

The critical breakdown displacement, Dc, in which friction drops to its sliding value, can be made dependent on event size by specifying friction to be a function of variables other than slip. Two such friction laws are examined here. The first is designed to achieve accuracy and smoothness in discrete numerical calculations. Consistent resolution throughout an evolving rupture is achieved by specifying friction as a function of elapsed time after peak stress is reached. Such a time-weakening model produces Dc and fracture energy proportional to the square root of distance rupture has propagated in the case of uniform stress drop. The second friction law is more physically motivated. Energy loss in a damage zone outside the slip zone has the effect of increasing Dc and limiting peak slip velocity (Andrews, 1976). This article demonstrates a converse effect, that artificially limiting slip velocity on a fault in an elastic medium has a toughening effect, increasing fracture energy and Dc proportionally to rupture propagation distance in the case of uniform stress drop. Both the time-weakening and the velocity-toughening models can be used in calculations with heterogeneous stress drop.

Displacement damage and predicted non-ionizing energy loss in GaAs

NASA Astrophysics Data System (ADS)

Gao, Fei; Chen, Nanjun; Hernandez-Rivera, Efrain; Huang, Danhong; LeVan, Paul D.

2017-03-01

Large-scale molecular dynamics (MD) simulations, along with bond-order interatomic potentials, have been applied to study the defect production for lattice atom recoil energies from 500 eV to 20 keV in gallium arsenide (GaAs). At low energies, the most surviving defects are single interstitials and vacancies, and only 20% of the interstitial population is contained in clusters. However, a direct-impact amorphization in GaAs occurs with a high degree of probability during the cascade lifetime for Ga PKAs (primary knock-on atoms) with energies larger than 2 keV. The results reveal a non-linear defect production that increases with the PKA energy. The damage density within a cascade core is evaluated, and used to develop a model that describes a new energy partition function. Based on the MD results, we have developed a model to determine the non-ionizing energy loss (NIEL) in GaAs, which can be used to predict the displacement damage degradation induced by space radiation on electronic components. The calculated NIEL predictions are compared with the available data, thus validating the NIEL model developed in this study.

Proton Effects and Test Issues for Satellite Designers

NASA Technical Reports Server (NTRS)

Marshall, Cheryl J.; Marshall, Paul W.

1999-01-01

Microelectronic and photonic systems in the natural space environment are bombarded by a variety of charged particles including electrons, trapped protons, cosmic rays, and solar particles (protons and other heavy ions). These incident particles cause both ionizing and non-ionizing effects when traversing a device, and the effects can be either transient or permanent. The vast majority of the kinetic energy of an incident proton is lost to ionization, creating the single event effects (SEES) and total ionizing dose (TID) effects. However, the small portion of energy lost in non-ionizing processes causes atoms to be removed from their lattice sites and form permanent electrically active defects in semiconductor materials. These defects, i.e., "displacement damage," can significantly degrade device performance. In general, most of the displacement damage effects in the natural space environment can be attributed to protons since they are plentiful and extremely energetic (and therefore not readily shielded against). For this reason, we consider only proton induced displacement damage in this course. (Nevertheless, we identify solar cells as an important example of a case where both electron and proton damage can be important since only very light shielding is feasible.) The interested reader is encouraged to explore the three previous NSREC and RADECS short courses which also treat displacement damage issues for satellite applications. Part A of this segment of the short course introduces the space environment, proton shielding issues, and requirements specifications for proton-rich environments. In order to exercise the displacement damage analysis tools for on-orbit performance predictions, the requirements document must provide the relevant proton spectra in addition to the usual total ionizing dose-depth curves. Ion-solid interactions and the nature of the displacement damage they generate have been studied extensively for over half a century, yet they still remain a subject of investigation. In this section, a description of the mechanisms by which displacement damage is produced will be followed by a summary of the major consequences for device performance in a space environment. Often the degradation of a device parameter can be characterized by a damage factor (measured in a laboratory using monoenergetic protons) that is simply the change in a particular electrical or optical parameter per unit proton fluence. In addition, we will describe the concept of a non-ionizing energy loss rate (NIEL) which quantifies that portion of the energy lost by an incident ion that goes into displacements. It has been calculated as a function of proton energy, and is analogous to (and has the same units as) the linear energy transfer (LET) for ionizing energy. We will discover that, to first order, the calculated NIEL describes the energy dependence of the measured device damage factors. This observation provides the basis for predicting proton induced device degradation in a space environment based on both the calculated NIEL and relatively few laboratory test measurements. The methodology of such on-orbit device performance predictions will be described, as well as the limitations. Several classes of devices for which displacement damage is a significant (if not the dominant) mode of radiation induced degradation will be presented.

Boundary displacement measurements using multi-energy soft x-rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tritz, K., E-mail: ktritz@pppl.gov; Stutman, D.; Diallo, A.

The Multi-Energy Soft X-ray (ME-SXR) system on NSTX provides radial profiles of soft X-ray emission, measured through a set of filters with varying thickness, which have been used to reconstruct the electron temperature on fast time scales (∼10 kHz). In addition to this functionality, here we show that the ME-SXR system can be used to measure the boundary displacement of the NSTX plasma with a few mm spatial resolution during magnetohydrodyamic (MHD) activity. Boundary displacement measurements can serve to inform theoretical predictions of neoclassical toroidal viscosity, and will be used to investigate other edge phenomena on NSTX-U. For example, boundary measurementsmore » using filtered SXR measurements can provide information on pedestal steepness and dynamic evolution leading up to and during edge localized modes (ELMs). Future applications include an assessment of a simplified, filtered SXR edge detection system as well as its suitability for real-time non-magnetic boundary feedback for ELMs, MHD, and equilibrium position control.« less

Displacement efficiency of alternative energy and trans-provincial imported electricity in China.

PubMed

Hu, Yuanan; Cheng, Hefa

2017-02-17

China has invested heavily on alternative energy, but the effectiveness of such energy sources at substituting the dominant coal-fired generation remains unknown. Here we analyse the displacement of fossil-fuel-generated electricity by alternative energy, primarily hydropower, and by trans-provincial imported electricity in China between 1995 and 2014 using two-way fixed-effects panel regression models. Nationwide, each unit of alternative energy displaces nearly one-quarter of a unit of fossil-fuel-generated electricity, while each unit of imported electricity (regardless of the generation source) displaces ∼0.3 unit of fossil-fuel electricity generated locally. Results from the six regional grids indicate that significant displacement of fossil-fuel-generated electricity occurs once the share of alternative energy in the electricity supply mix exceeds ∼10%, which is accompanied by 10-50% rebound in the consumption of fossil-fuel-generated electricity. These findings indicate the need for a policy that integrates carbon taxation, alternative energy and energy efficiency to facilitate China's transition towards a low-carbon economy.

Displacement efficiency of alternative energy and trans-provincial imported electricity in China

NASA Astrophysics Data System (ADS)

Hu, Yuanan; Cheng, Hefa

2017-02-01

China has invested heavily on alternative energy, but the effectiveness of such energy sources at substituting the dominant coal-fired generation remains unknown. Here we analyse the displacement of fossil-fuel-generated electricity by alternative energy, primarily hydropower, and by trans-provincial imported electricity in China between 1995 and 2014 using two-way fixed-effects panel regression models. Nationwide, each unit of alternative energy displaces nearly one-quarter of a unit of fossil-fuel-generated electricity, while each unit of imported electricity (regardless of the generation source) displaces ~0.3 unit of fossil-fuel electricity generated locally. Results from the six regional grids indicate that significant displacement of fossil-fuel-generated electricity occurs once the share of alternative energy in the electricity supply mix exceeds ~10%, which is accompanied by 10-50% rebound in the consumption of fossil-fuel-generated electricity. These findings indicate the need for a policy that integrates carbon taxation, alternative energy and energy efficiency to facilitate China's transition towards a low-carbon economy.

Characterization of the energy-dependent uncertainty and correlation in silicon neutron displacement damage metrics

NASA Astrophysics Data System (ADS)

Griffin, Patrick; Rochman, Dimitri; Koning, Arjan

2017-09-01

A rigorous treatment of the uncertainty in the underlying nuclear data on silicon displacement damage metrics is presented. The uncertainty in the cross sections and recoil atom spectra are propagated into the energy-dependent uncertainty contribution in the silicon displacement kerma and damage energy using a Total Monte Carlo treatment. An energy-dependent covariance matrix is used to characterize the resulting uncertainty. A strong correlation between different reaction channels is observed in the high energy neutron contributions to the displacement damage metrics which supports the necessity of using a Monte Carlo based method to address the nonlinear nature of the uncertainty propagation.

10 CFR 590.209 - Exchanges by displacement.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 4 2011-01-01 2011-01-01 false Exchanges by displacement. 590.209 Section 590.209 Energy... Natural Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...

10 CFR 590.209 - Exchanges by displacement.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 4 2010-01-01 2010-01-01 false Exchanges by displacement. 590.209 Section 590.209 Energy... Natural Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...

10 CFR 590.209 - Exchanges by displacement.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 4 2014-01-01 2014-01-01 false Exchanges by displacement. 590.209 Section 590.209 Energy... Natural Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...

10 CFR 590.209 - Exchanges by displacement.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 4 2012-01-01 2012-01-01 false Exchanges by displacement. 590.209 Section 590.209 Energy... Natural Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...

10 CFR 590.209 - Exchanges by displacement.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 4 2013-01-01 2013-01-01 false Exchanges by displacement. 590.209 Section 590.209 Energy... Natural Gas § 590.209 Exchanges by displacement. Any importer of natural gas may enter into an exchange by displacement agreement without the prior authorization of the Assistant Secretary when the net effect of the...

On the theory of intensity distributions of tornadoes and other low pressure systems

NASA Astrophysics Data System (ADS)

Schielicke, Lisa; Névir, Peter

Approaching from a theoretical point of view, this work presents a theory which unifies intensity distributions of different low pressure systems, based on an energy of displacement. Resulting from a generalized Boltzmann distribution, the expression of this energy of displacement is obtained by radial integration over the forces which are in balance with the pressure gradient force in the horizontal equation of motion. A scale analysis helps to find out which balance of forces prevail. According to the prevailing balances, the expression of the energy of displacement differs for various depressions. Investigating the system at the moment of maximum intensity, the energy of displacement can be interpreted as the work that has to be done to generate and finally eliminate the pressure anomaly, respectively. By choosing the appropriate balance of forces, number-intensity (energy of displacement) distributions show exponential behavior with the same decay rate β for tornadoes and cyclones, if tropical and extra-tropical cyclones are investigated together. The decay rate is related to a characteristic (universal) scale of the energy of displacement which has approximately the value Eu = β- 1 ≈ 1000 m 2s - 2 . In consequence, while the different balances of forces cause the scales of velocity, the energy of displacement scale seems to be universal for all low pressure systems. Additionally, if intensity is expressed as lifetime minimum pressure, the number-intensity (pressure) distributions should be power law distributed. Moreover, this work points out that the choice of the physical quantity which represents the intensity is important concerning the behavior of intensity distributions. Various expressions of the intensity like velocity, kinetic energy, energy of displacement and pressure are possible, but lead to different behavior of the distributions.

In Vitro Comparison of a Novel Single Probe Dual-Energy Lithotripter to Current Devices.

PubMed

Carlos, Evan C; Wollin, Daniel A; Winship, Brenton B; Jiang, Ruiyang; Radvak, Daniela; Chew, Ben H; Gustafson, Michael R; Simmons, W Neal; Zhong, Pei; Preminger, Glenn M; Lipkin, Michael E

2018-06-01

The LithoClast Trilogy is a novel single probe, dual-energy lithotripter with ultrasonic (US) vibration and electromagnetic impact forces. ShockPulse and LithoClast Select are existing lithotripters that also use a combination of US and mechanical impact energies. We compared the efficacy and tip motion of these devices in an in vitro setting. Begostones, in the ratio 15:3, were used in all trials. Test groups were Trilogy, ShockPulse, Select ultrasound (US) only, and Select ultrasound with pneumatic (USP). For clearance testing, a single investigator facile with each lithotripter fragmented 10 stones per device. For drill testing, a hands-free apparatus with a submerged balance was used to apply 1 or 2 lbs of pressure on a stone in contact with the device tip. High-speed photography was used to assess Trilogy and ShockPulse's probe tip motion. Select-USP was slowest and Trilogy fastest on clearance testing (p < 0.01). On 1 lbs drill testing, Select-US was slowest (p = 0.001). At 2 lbs, ShockPulse was faster than Select US (p = 0.027), but did not significantly outpace Trilogy nor Select-USP. At either weight, there was no significant difference between Trilogy and ShockPulse. During its US function, Trilogy's maximum downward tip displacement was 0.041 mm relative to 0.0025 mm with ShockPulse. Trilogy had 0.25 mm of maximum downward displacement during its impactor function while ShockPulse had 0.01 mm. Single probe dual-energy devices, such as Trilogy and ShockPulse, represent the next generation of lithotripters. Trilogy more efficiently cleared stone than currently available devices, which could be explained by its larger probe diameter and greater downward tip displacement during both US and impactor functions.

Displacement efficiency of alternative energy and trans-provincial imported electricity in China

PubMed Central

Hu, Yuanan; Cheng, Hefa

2017-01-01

China has invested heavily on alternative energy, but the effectiveness of such energy sources at substituting the dominant coal-fired generation remains unknown. Here we analyse the displacement of fossil-fuel-generated electricity by alternative energy, primarily hydropower, and by trans-provincial imported electricity in China between 1995 and 2014 using two-way fixed-effects panel regression models. Nationwide, each unit of alternative energy displaces nearly one-quarter of a unit of fossil-fuel-generated electricity, while each unit of imported electricity (regardless of the generation source) displaces ∼0.3 unit of fossil-fuel electricity generated locally. Results from the six regional grids indicate that significant displacement of fossil-fuel-generated electricity occurs once the share of alternative energy in the electricity supply mix exceeds ∼10%, which is accompanied by 10–50% rebound in the consumption of fossil-fuel-generated electricity. These findings indicate the need for a policy that integrates carbon taxation, alternative energy and energy efficiency to facilitate China's transition towards a low-carbon economy. PMID:28211467

On the influence of dynamic stress variations on strain accumulation in fault zones

NASA Astrophysics Data System (ADS)

Grigoriev, A. S.; Shilko, E. V.; Astafurov, S. V.; Dimaki, A. V.; Vysotsky, E. M.; Psakhie, S. G.

2015-10-01

In this paper, a numerical study of the influence of the stress state of interface of the block medium structural elements on the deformation response of interface to the dynamic impacts. It is shown that the basic characteristics of the stress state determining the deformation response of the interface are the values of shear stress and mean stress. It is found that the dependence of the irreversible displacement at the interface zone initiated by dynamic impact on the reduced shear stress is described by the logistic function. Herewith, the influence of the mean stress and dynamic impact energy on the value of displacement initiated by dynamic impact can be taken into account by dependence of the logistic function numerator on these parameters.

Model for transport and reaction of defects and carriers within displacement cascades in gallium arsenide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wampler, William R., E-mail: wrwampl@sandia.gov; Myers, Samuel M.

A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers,more » and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.« less

Mechanical Design and Analysis of a Unilateral Cervical Spinal Cord Contusion Injury Model in Non-Human Primates.

PubMed

Sparrey, Carolyn J; Salegio, Ernesto A; Camisa, William; Tam, Horace; Beattie, Michael S; Bresnahan, Jacqueline C

2016-06-15

Non-human primate (NHP) models of spinal cord injury better reflect human injury and provide a better foundation to evaluate potential treatments and functional outcomes. We combined finite element (FE) and surrogate models with impact data derived from in vivo experiments to define the impact mechanics needed to generate a moderate severity unilateral cervical contusion injury in NHPs (Macaca mulatta). Three independent variables (impactor displacement, alignment, and pre-load) were examined to determine their effects on tissue level stresses and strains. Mechanical measures of peak force, peak displacement, peak energy, and tissue stiffness were analyzed as potential determinants of injury severity. Data generated from FE simulations predicted a lateral shift of the spinal cord at high levels of compression (>64%) during impact. Submillimeter changes in mediolateral impactor position over the midline increased peak impact forces (>50%). Surrogate cords established a 0.5 N pre-load protocol for positioning the impactor tip onto the dural surface to define a consistent dorsoventral baseline position before impact, which corresponded with cerebrospinal fluid displacement and entrapment of the spinal cord against the vertebral canal. Based on our simulations, impactor alignment and pre-load were strong contributors to the variable mechanical and functional outcomes observed in in vivo experiments. Peak displacement of 4 mm after a 0.5N pre-load aligned 0.5-1.0 mm over the midline should result in a moderate severity injury; however, the observed peak force and calculated peak energy and tissue stiffness are required to properly characterize the severity and variability of in vivo NHP contusion injuries.

Development of Finite Elements for Two-Dimensional Structural Analysis Using the Integrated Force Method

NASA Technical Reports Server (NTRS)

Kaljevic, Igor; Patnaik, Surya N.; Hopkins, Dale A.

1996-01-01

The Integrated Force Method has been developed in recent years for the analysis of structural mechanics problems. This method treats all independent internal forces as unknown variables that can be calculated by simultaneously imposing equations of equilibrium and compatibility conditions. In this paper a finite element library for analyzing two-dimensional problems by the Integrated Force Method is presented. Triangular- and quadrilateral-shaped elements capable of modeling arbitrary domain configurations are presented. The element equilibrium and flexibility matrices are derived by discretizing the expressions for potential and complementary energies, respectively. The displacement and stress fields within the finite elements are independently approximated. The displacement field is interpolated as it is in the standard displacement method, and the stress field is approximated by using complete polynomials of the correct order. A procedure that uses the definitions of stress components in terms of an Airy stress function is developed to derive the stress interpolation polynomials. Such derived stress fields identically satisfy the equations of equilibrium. Moreover, the resulting element matrices are insensitive to the orientation of local coordinate systems. A method is devised to calculate the number of rigid body modes, and the present elements are shown to be free of spurious zero-energy modes. A number of example problems are solved by using the present library, and the results are compared with corresponding analytical solutions and with results from the standard displacement finite element method. The Integrated Force Method not only gives results that agree well with analytical and displacement method results but also outperforms the displacement method in stress calculations.

[Correlation analysis between residual displacement and hip function after reconstruction of acetabular fractures].

PubMed

Ma, Kunlong; Fang, Yue; Luan, Fujun; Tu, Chongqi; Yang, Tianfu

2012-03-01

To investigate the relationships between residual displacement of weight-bearing and non weight-bearing zones (gap displacement and step displacement) and hip function by analyzing the CT images after reconstruction of acetabular fractures. The CT measures and clinical outcome were retrospectively analyzed from 48 patients with displaced acetabular fracture between June 2004 and June 2009. All patients were treated by open reduction and internal fixation, and were followed up 24 to 72 months (mean, 36 months); all fractures healed after operation. The residual displacement involved the weight-bearing zone in 30 cases (weight-bearing group), and involved the non weight-bearing zone in 18 cases (non weight-bearing group). The clinical outcomes were evaluated by Merle d'Aubigné-Postel criteria, and the reduction of articular surface by CT images, including the maximums of two indexes (gap displacement and step displacement). All the data were analyzed in accordance with the Spearman rank correlation coefficient analysis. There was strong negative correlation between the hip function and the residual displacement values in weight-bearing group (r(s) = -0.722, P = 0.001). But there was no correlation between the hip function and the residual displacement values in non weight-bearing group (r(s) = 0.481, P = 0.059). The results of clinical follow-up were similar to the correlation analysis results. In weight-bearing group, the hip function had strong negative correlation with step displacement (r(s) = 0.825, P = 0.002), but it had no correlation with gap displacement (r(s) = 0.577, P = 0.134). In patients with acetabular fracture, the hip function has correlation not only with the extent of the residual displacement but also with the location of the residual displacement, so the residual displacement of weight-bearing zone is a key factor to affect the hip function. In patients with residual displacement in weight-bearing zone, the bigger the step displacement is, the worse the hip function is.

Exploration of the psychophysics of a motion displacement hyperacuity stimulus.

PubMed

Verdon-Roe, Gay Mary; Westcott, Mark C; Viswanathan, Ananth C; Fitzke, Frederick W; Garway-Heath, David F

2006-11-01

To explore the summation properties of a motion-displacement hyperacuity stimulus with respect to stimulus area and luminance, with the goal of applying the results to the development of a motion-displacement test (MDT) for the detection of early glaucoma. A computer-generated line stimulus was presented with displacements randomized between 0 and 40 minutes of arc (min arc). Displacement thresholds (50% seen) were compared for stimuli of equal area but different edge length (orthogonal to the direction of motion) at four retinal locations. Also, MDT thresholds were recorded at five values of Michelson contrast (25%-84%) for each of five line lengths (11-128 min arc) at a single nasal location (-27,3). Frequency-of-seeing (FOS) curves were generated and displacement thresholds and interquartile ranges (IQR, 25%-75% seen) determined by probit analysis. Equivalent displacement thresholds were found for stimuli of equal area but half the edge length. Elevations of thresholds and IQR were demonstrated as line length and contrast were reduced. Equivalent displacement thresholds were also found for stimuli of equivalent energy (stimulus area x [stimulus luminance - background luminance]), in accordance with Ricco's law. There was a linear relationship (slope -0.5) between log MDT threshold and log stimulus energy. Stimulus area, rather than edge length, determined displacement thresholds within the experimental conditions tested. MDT thresholds are linearly related to the square root of the total energy of the stimulus. A new law, the threshold energy-displacement (TED) law, is proposed to apply to MDT summation properties, giving the relationship T = K logE where, T is the MDT threshold, Kis the constant, and E is the stimulus energy.

Mixed models and reduced/selective integration displacement models for nonlinear analysis of curved beams

NASA Technical Reports Server (NTRS)

Noor, A. K.; Peters, J. M.

1981-01-01

Simple mixed models are developed for use in the geometrically nonlinear analysis of deep arches. A total Lagrangian description of the arch deformation is used, the analytical formulation being based on a form of the nonlinear deep arch theory with the effects of transverse shear deformation included. The fundamental unknowns comprise the six internal forces and generalized displacements of the arch, and the element characteristic arrays are obtained by using Hellinger-Reissner mixed variational principle. The polynomial interpolation functions employed in approximating the forces are one degree lower than those used in approximating the displacements, and the forces are discontinuous at the interelement boundaries. Attention is given to the equivalence between the mixed models developed herein and displacement models based on reduced integration of both the transverse shear and extensional energy terms. The advantages of mixed models over equivalent displacement models are summarized. Numerical results are presented to demonstrate the high accuracy and effectiveness of the mixed models developed and to permit a comparison of their performance with that of other mixed models reported in the literature.

Asymptotic forms for the energy of force-free magnetic field ion figurations of translational symmetry

NASA Technical Reports Server (NTRS)

Sturrock, P. A.; Antiochos, S. K.; Klinchuk, J. A.; Roumeliotis, G.

1994-01-01

It is known from computer calculations that if a force-free magnetic field configuration is stressed progressively by footpoint displacements, the configuration expands and approaches the open configuration with the same surface flux distribution and the energy of the field increases progressively. For configurations of translationalsymmetry, it has been found empirically that the energy tends asymptotically to a certain functional form. It is here shown that analysis of a simple model of the asymptotic form of force-free fields of translational symmetry leads to and therefore justifies this functional form. According to this model, the field evolves in a well-behaved manner with no indication of instability or loss of equilibrium.

Impact of ASTM Standard E722 update on radiation damage metrics

DOE Office of Scientific and Technical Information (OSTI.GOV)

DePriest, Kendall Russell

2014-06-01

The impact of recent changes to the ASTM Standard E722 is investigated. The methodological changes in the production of the displacement kerma factors for silicon has significant impact for some energy regions of the 1-MeV(Si) equivalent fluence response function. When evaluating the integral over all neutrons energies in various spectra important to the SNL electronics testing community, the change in the response results in an increase in the total 1-MeV(Si) equivalent fluence of 2 7%. Response functions have been produced and are available for users of both the NuGET and MCNP codes.

Thermodynamic Insights into Effects of Water Displacement and Rearrangement upon Ligand Modification using Molecular Dynamics Simulations.

PubMed

Wahl, Joel; Smiesko, Martin

2018-05-04

Computational methods, namely Molecular Dynamics Simulations (MD simulations) in combination with Inhomogeneous Fluid Solvation Theory (IFST) were used to retrospectively investigate various cases of ligand structure modifications that led to the displacement of binding site water molecules. Our findings are that the water displacement per se is energetically unfavorable in the discussed examples, and that it is merely the fine balance between change in protein-ligand interaction energy, ligand solvation free energies and binding site solvation free energies that determine if water displacement is favorable or not. We furthermore evaluated if we can reproduce experimental binding affinities by a computational approach combining changes in solvation free energies with changes in protein-ligand interaction energies and entropies. In two of the seven cases, this estimation led to large errors, implying that accurate predictions of relative binding free energies based on solvent thermodynamics is challenging. Still, MD simulations can provide insights into which water molecules can be targeted for displacement. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

First-and Second-Order Displacement Transfer Functions for Structural Shape Calculations Using Analytically Predicted Surface Strains

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2012-01-01

New first- and second-order displacement transfer functions have been developed for deformed shape calculations of nonuniform cross-sectional beam structures such as aircraft wings. The displacement transfer functions are expressed explicitly in terms of beam geometrical parameters and surface strains (uniaxial bending strains) obtained at equally spaced strain stations along the surface of the beam structure. By inputting the measured or analytically calculated surface strains into the displacement transfer functions, one could calculate local slopes, deflections, and cross-sectional twist angles of the nonuniform beam structure for mapping the overall structural deformed shapes for visual display. The accuracy of deformed shape calculations by the first- and second-order displacement transfer functions are determined by comparing these values to the analytically predicted values obtained from finite element analyses. This comparison shows that the new displacement transfer functions could quite accurately calculate the deformed shapes of tapered cantilever tubular beams with different tapered angles. The accuracy of the present displacement transfer functions also are compared to those of the previously developed displacement transfer functions.

Metal-cluster ionization energy: A profile-insensitive exact expression for the size effect

NASA Astrophysics Data System (ADS)

Seidl, Michael; Perdew, John P.; Brajczewska, Marta; Fiolhais, Carlos

1997-05-01

The ionization energy of a large spherical metal cluster of radius R is I(R)=W+(+c)/R, where W is the bulk work function and c~-0.1 is a material-dependent quantum correction to the electrostatic size effect. We present 'Koopmans' and 'displaced-profile change-in-self-consistent-field' expressions for W and c within the ordinary and stabilized-jellium models. These expressions are shown to be exact and equivalent when the exact density profile of a large neutral cluster is employed; these equivalences generalize the Budd-Vannimenus theorem. With an approximate profile obtained from a restricted variational calculation, the 'displaced-profile' expressions are the more accurate ones. This profile insensitivity is important, because it is not practical to extract c from solutions of the Kohn-Sham equations for small metal clusters.

Fruits and vegetables displace, but do not decrease, total energy in school lunches.

PubMed

Bontrager Yoder, Andrea B; Schoeller, Dale A

2014-08-01

The high overweight and obesity prevalence among US children is a well-established public health concern. Diet is known to play a causal role in obesity. Increasing fruit and vegetable (FV) consumption to recommended levels is proposed to help reduce obesity, because their bulk and low energy density are believed to reduce energy-dense food consumption (volume displacement hypothesis). This study tests this hypothesis at the lunch meal among upper-elementary students participating in a Farm to School (F2S) program. Digital photographs of students' school lunch trays were visually analyzed to identify the food items and amounts that were present and consumed before and after the meal. Using the USDA Nutrient Database, total and FV-only energy were calculated for each tray. Analysis of total- and non-FV energy intake was performed according to (1) levels of FV energy intake, (2) FV energy density, and (3) previous years of Farm to School programming. Higher intake of FV energy displaced non-FV energy, but total energy did not decrease across FV energy intake groups. High-FV-energy-density trays showed lower non-FV energy intake than low-FV-energy-density trays (470±179 vs. 534±219 kcal; p<0.0001). Trays from schools with more previous years of F2S programming decreased total and non-FV energy intake from school lunches (p for trend<0.0001, both). Increased FV consumption reduces non-FV energy intake, but does not reduce total energy intake. Therefore, this study does not support the volume displacement hypothesis and suggests calorie displacement instead.

A linkage analysis toolkit for studying allosteric networks in ion channels

PubMed Central

2013-01-01

A thermodynamic approach to studying allosterically regulated ion channels such as the large-conductance voltage- and Ca2+-dependent (BK) channel is presented, drawing from principles originally introduced to describe linkage phenomena in hemoglobin. In this paper, linkage between a principal channel component and secondary elements is derived from a four-state thermodynamic cycle. One set of parallel legs in the cycle describes the “work function,” or the free energy required to activate the principal component. The second are “lever operations” activating linked elements. The experimental embodiment of this linkage cycle is a plot of work function versus secondary force, whose asymptotes are a function of the parameters (displacements and interaction energies) of an allosteric network. Two essential work functions play a role in evaluating data from voltage-clamp experiments. The first is the conductance Hill energy WH[g], which is a “local” work function for pore activation, and is defined as kT times the Hill transform of the conductance (G-V) curve. The second is the electrical capacitance energy WC[q], representing “global” gating charge displacement, and is equal to the product of total gating charge per channel times the first moment (VM) of normalized capacitance (slope of Q-V curve). Plots of WH[g] and WC[q] versus voltage and Ca2+ potential can be used to measure thermodynamic parameters in a model-independent fashion of the core gating constituents (pore, voltage-sensor, and Ca2+-binding domain) of BK channel. The method is easily generalized for use in studying other allosterically regulated ion channels. The feasibility of performing linkage analysis from patch-clamp data were explored by simulating gating and ionic currents of a 17-particle model BK channel in response to a slow voltage ramp, which yielded interaction energies deviating from their given values in the range of 1.3 to 7.2%. PMID:23250867

Mechanical Design and Analysis of a Unilateral Cervical Spinal Cord Contusion Injury Model in Non-Human Primates

PubMed Central

Salegio, Ernesto A.; Camisa, William; Tam, Horace; Beattie, Michael S.; Bresnahan, Jacqueline C.

2016-01-01

Abstract Non-human primate (NHP) models of spinal cord injury better reflect human injury and provide a better foundation to evaluate potential treatments and functional outcomes. We combined finite element (FE) and surrogate models with impact data derived from in vivo experiments to define the impact mechanics needed to generate a moderate severity unilateral cervical contusion injury in NHPs (Macaca mulatta). Three independent variables (impactor displacement, alignment, and pre-load) were examined to determine their effects on tissue level stresses and strains. Mechanical measures of peak force, peak displacement, peak energy, and tissue stiffness were analyzed as potential determinants of injury severity. Data generated from FE simulations predicted a lateral shift of the spinal cord at high levels of compression (>64%) during impact. Submillimeter changes in mediolateral impactor position over the midline increased peak impact forces (>50%). Surrogate cords established a 0.5 N pre-load protocol for positioning the impactor tip onto the dural surface to define a consistent dorsoventral baseline position before impact, which corresponded with cerebrospinal fluid displacement and entrapment of the spinal cord against the vertebral canal. Based on our simulations, impactor alignment and pre-load were strong contributors to the variable mechanical and functional outcomes observed in in vivo experiments. Peak displacement of 4 mm after a 0.5N pre-load aligned 0.5–1.0 mm over the midline should result in a moderate severity injury; however, the observed peak force and calculated peak energy and tissue stiffness are required to properly characterize the severity and variability of in vivo NHP contusion injuries. PMID:26670940

Chemical evolution via beta decay: a case study in strontium-90

NASA Astrophysics Data System (ADS)

Marks, N. A.; Carter, D. J.; Sassi, M.; Rohl, A. L.; Sickafus, K. E.; Uberuaga, B. P.; Stanek, C. R.

2013-02-01

Using 90Sr as a representative isotope, we present a framework for understanding beta decay within the solid state. We quantify three key physical and chemical principles, namely momentum-induced recoil during the decay event, defect creation due to physical displacement, and chemical evolution over time. A fourth effect, that of electronic excitation, is also discussed, but this is difficult to quantify and is strongly material dependent. The analysis is presented for the specific cases of SrTiO3 and SrH2. By comparing the recoil energy with available threshold displacement data we show that in many beta-decay situations defects such as Frenkel pairs will not be created during decay as the energy transfer is too low. This observation leads to the concept of chemical evolution over time, which we quantify using density functional theory. Using a combination of Bader analysis, phonon calculations and cohesive energy calculations, we show that beta decay leads to counter-intuitive behavior that has implications for nuclear waste storage and novel materials design.

Chemical evolution via beta decay: a case study in strontium-90.

PubMed

Marks, N A; Carter, D J; Sassi, M; Rohl, A L; Sickafus, K E; Uberuaga, B P; Stanek, C R

2013-02-13

Using (90)Sr as a representative isotope, we present a framework for understanding beta decay within the solid state. We quantify three key physical and chemical principles, namely momentum-induced recoil during the decay event, defect creation due to physical displacement, and chemical evolution over time. A fourth effect, that of electronic excitation, is also discussed, but this is difficult to quantify and is strongly material dependent. The analysis is presented for the specific cases of SrTiO(3) and SrH(2). By comparing the recoil energy with available threshold displacement data we show that in many beta-decay situations defects such as Frenkel pairs will not be created during decay as the energy transfer is too low. This observation leads to the concept of chemical evolution over time, which we quantify using density functional theory. Using a combination of Bader analysis, phonon calculations and cohesive energy calculations, we show that beta decay leads to counter-intuitive behavior that has implications for nuclear waste storage and novel materials design.

Measurements of wind vectors, eddy momentum transports, and energy conversions in Jupiter's atmosphere from Voyager 1 images

NASA Astrophysics Data System (ADS)

Beebe, R. F.; Ingersoll, A. P.; Hunt, G. E.; Mitchell, J. L.; Muller, J.-P.

1980-01-01

Voyager 1 narrow-angle images were used to obtain displacements of features down to 100 to 200 km in size over intervals of 10 hours. A global map of velocity vectors and longitudinally averaged zonal wind vectors as functions of the latitude, is presented and discussed

Schrödinger propagation of initial discontinuities leads to divergence of moments

NASA Astrophysics Data System (ADS)

Marchewka, A.; Schuss, Z.

2009-09-01

We show that the large phase expansion of the Schrödinger propagation of an initially discontinuous wave function leads to the divergence of average energy, momentum, and displacement, rendering them unphysical states. If initially discontinuous wave functions are considered to be approximations to continuous ones, the determinant of the spreading rate of these averages is the maximal gradient of the initial wave function. Therefore a dilemma arises between the inclusion of discontinuous wave functions in quantum mechanics and the requirement of finite moments.

Acoustic Rectification in Dispersive Media

NASA Technical Reports Server (NTRS)

Cantrell, John H.

2008-01-01

It is shown that the shapes of acoustic radiation-induced static strain and displacement pulses (rectified acoustic pulses) are defined locally by the energy density of the generating waveform. Dispersive properties are introduced analytically by assuming that the rectified pulses are functionally dependent on a phase factor that includes both dispersive and nonlinear terms. The dispersion causes an evolutionary change in the shape of the energy density profile that leads to the generation of solitons experimentally observed in fused silica.

The Role of Interfacial Water in Protein-Ligand Binding: Insights from the Indirect Solvent Mediated Potential of Mean Force.

PubMed

Cui, Di; Zhang, Bin W; Matubayasi, Nobuyuki; Levy, Ronald M

2018-02-13

Classical density functional theory (DFT) can be used to relate the thermodynamic properties of solutions to the indirect solvent mediated part of the solute-solvent potential of mean force (PMF). Standard, but powerful numerical methods can be used to estimate the solute-solvent PMF from which the indirect part can be extracted. In this work we show how knowledge of the direct and indirect parts of the solute-solvent PMF for water at the interface of a protein receptor can be used to gain insights about how to design tighter binding ligands. As we show, the indirect part of the solute-solvent PMF is equal to the sum of the 1-body (energy + entropy) terms in the inhomogeneous solvation theory (IST) expansion of the solvation free energy. To illustrate the effect of displacing interfacial water molecules with particular direct/indirect PMF signatures on the binding of ligands, we carry out simulations of protein binding with several pairs of congeneric ligands. We show that interfacial water locations that contribute favorably or unfavorably at the 1-body level (energy + entropy) to the solvation free energy of the solute can be targeted as part of the ligand design process. Water locations where the indirect PMF is larger in magnitude provide better targets for displacement when adding a functional group to a ligand core.

Fruits and Vegetables Displace, But Do Not Decrease, Total Energy in School Lunches

PubMed Central

Schoeller, Dale A.

2014-01-01

Abstract Background: The high overweight and obesity prevalence among US children is a well-established public health concern. Diet is known to play a causal role in obesity. Increasing fruit and vegetable (FV) consumption to recommended levels is proposed to help reduce obesity, because their bulk and low energy density are believed to reduce energy-dense food consumption (volume displacement hypothesis). This study tests this hypothesis at the lunch meal among upper-elementary students participating in a Farm to School (F2S) program. Methods: Digital photographs of students' school lunch trays were visually analyzed to identify the food items and amounts that were present and consumed before and after the meal. Using the USDA Nutrient Database, total and FV-only energy were calculated for each tray. Analysis of total- and non-FV energy intake was performed according to (1) levels of FV energy intake, (2) FV energy density, and (3) previous years of Farm to School programming. Results: Higher intake of FV energy displaced non-FV energy, but total energy did not decrease across FV energy intake groups. High-FV-energy-density trays showed lower non-FV energy intake than low-FV-energy-density trays (470±179 vs. 534±219 kcal; p<0.0001). Trays from schools with more previous years of F2S programming decreased total and non-FV energy intake from school lunches (p for trend<0.0001, both). Conclusions: Increased FV consumption reduces non-FV energy intake, but does not reduce total energy intake. Therefore, this study does not support the volume displacement hypothesis and suggests calorie displacement instead. PMID:24988122

Analysis of delamination related fracture processes in composites

NASA Technical Reports Server (NTRS)

Armanios, Erian A.

1992-01-01

An anisotropic thin walled closed section beam theory was developed based on an asymptotical analysis of the shell energy functional. The displacement field is not assumed a priori and emerges as a result of the analysis. In addition to the classical out-of-plane torsional warping, two new contributions are identified namely, axial strain and bending warping. A comparison of the derived governing equations confirms the theory developed by Reissner and Tsai. Also, explicit closed form expressions for the beam stiffness coefficients, the stress and displacement fields are provided. The predictions of the present theory were validated by comparison with finite element simulation, other closed form analyses and test data.

A distributed parameter electromechanical model for bimorph piezoelectric energy harvesters based on the refined zigzag theory

NASA Astrophysics Data System (ADS)

Chen, Chung-De

2018-04-01

In this paper, a distributed parameter electromechanical model for bimorph piezoelectric energy harvesters based on the refined zigzag theory (RZT) is developed. In this model, the zigzag function is incorporated into the axial displacement, and the zigzag distribution of the displacement between the adjacent layers of the bimorph structure can be considered. The governing equations, including three equations of motions and one equation of circuit, are derived using Hamilton’s principle. The natural frequency, its corresponding modal function and the steady state response of the base excitation motion are given in exact forms. The presented results are benchmarked with the finite element method and two beam theories, the first-order shear deformation theory and the classical beam theory. Comparing examples shows that the RZT provides predictions of output voltage and generated power at high accuracy, especially for the case of a soft middle layer. Variation of the parameters, such as the beam thickness, excitation frequencies and the external electrical loads, is investigated and its effects on the performance of the energy harvesters are studied by using the RZT developed in this paper. Based on this refined theory, analysts and engineers can capture more details on the electromechanical behavior of piezoelectric harvesters.

Knowledge-Based Elastic Potentials for Docking Drugs or Proteins with Nucleic Acids

PubMed Central

Ge, Wei; Schneider, Bohdan; Olson, Wilma K.

2005-01-01

Elastic ellipsoidal functions defined by the observed hydration patterns around the DNA bases provide a new basis for measuring the recognition of ligands in the grooves of double-helical structures. Here a set of knowledge-based potentials suitable for quantitative description of such behavior is extracted from the observed positions of water molecules and amino acid atoms that form hydrogen bonds with the nitrogenous bases in high resolution crystal structures. Energies based on the displacement of hydrogen-bonding sites on drugs in DNA-crystal complexes relative to the preferred locations of water binding around the heterocyclic bases are low, pointing to the reliability of the potentials and the apparent displacement of water molecules by drug atoms in these structures. The validity of the energy functions has been further examined in a series of sequence substitution studies based on the structures of DNA bound to polyamides that have been designed to recognize the minor-groove edges of Watson-Crick basepairs. The higher energies of binding to incorrect sequences superimposed (without conformational adjustment or displacement of polyamide ligands) on observed high resolution structures confirm the hypothesis that the drug subunits associate with specific DNA bases. The knowledge-based functions also account satisfactorily for the measured free energies of DNA-polyamide association in solution and the observed sites of polyamide binding on nucleosomal DNA. The computations are generally consistent with mechanisms by which minor-groove binding ligands are thought to recognize DNA basepairs. The calculations suggest that the asymmetric distributions of hydrogen-bond-forming atoms on the minor-groove edge of the basepairs may underlie ligand discrimination of G·C from C·G pairs, in addition to the commonly believed role of steric hindrance. The analysis of polyamide-bound nucleosomal structures reveals other discrepancies in the expected chemical design, including unexpected contacts to DNA and modified basepair targets of some ligands. The ellipsoidal potentials thus appear promising as a mathematical tool for the study of drug- and protein-DNA interactions and for gaining new insights into DNA-binding mechanisms. PMID:15501936

Real-time sub-Ångstrom imaging of reversible and irreversible conformations in rhodium catalysts and graphene

NASA Astrophysics Data System (ADS)

Kisielowski, Christian; Wang, Lin-Wang; Specht, Petra; Calderon, Hector A.; Barton, Bastian; Jiang, Bin; Kang, Joo H.; Cieslinski, Robert

2013-07-01

The dynamic responses of a rhodium catalyst and a graphene sheet are investigated upon random excitation with 80 kV electrons. An extraordinary electron microscope stability and resolution allow studying temporary atom displacements from their equilibrium lattice sites into metastable sites across projected distances as short as 60 pm. In the rhodium catalyst, directed and reversible atom displacements emerge from excitations into metastable interstitial sites and surface states that can be explained by single atom trajectories. Calculated energy barriers of 0.13 eV and 1.05 eV allow capturing single atom trapping events at video rates that are stabilized by the Rh [110] surface corrugation. Molecular dynamics simulations reveal that randomly delivered electrons can also reversibly enhance the sp3 and the sp1 characters of the sp2-bonded carbon atoms in graphene. The underlying collective atom motion can dynamically stabilize characteristic atom displacements that are unpredictable by single atom trajectories. We detect three specific displacements and use two of them to propose a path for the irreversible phase transformation of a graphene nanoribbon into carbene. Collectively stabilized atom displacements greatly exceed the thermal vibration amplitudes described by Debye-Waller factors and their measured dose rate dependence is attributed to tunable phonon contributions to the internal energy of the systems. Our experiments suggest operating electron microscopes with beam currents as small as zepto-amperes/nm2 in a weak-excitation approach to improve on sample integrity and allow for time-resolved studies of conformational object changes that probe for functional behavior of catalytic surfaces or molecules.

Primary damage formation in bcc iron

NASA Astrophysics Data System (ADS)

Stoller, R. E.; Odette, G. R.; Wirth, B. D.

1997-11-01

Primary defect formation in bee iron has been extensively investigated using the methods of molecular dynamics (MD) and Monte Carlo (MC) simulation. This research has employed a modified version of the Finnis-Sinclair interatomic potential. MD was used in the simulation of displacement cascades with energies up to 40 keV and to examine the migration of the interstitial clusters that were observed to form in the cascade simulations. Interstitial cluster binding energies and the stable cluster configurations were determined by structural relaxation and energy minimization using a MC method with simulated annealing. Clusters containing up to 19 interstitials were examined. Taken together with the previous work, these new simulations provide a reasonably complete description of primary defect formation in iron. The results of the displacement cascade simulations have been used to characterize the energy and temperature dependence of primary defect formation in terms of two parameters: (1) the number of surviving point defects and (2) the fraction of the surviving defects that are contained in clusters. The number of surviving point defects is expressed as a fraction of the atomic displacements calculated using the secondary displacement model of Norgett-Robinson-Torrens (NRT). Although the results of the high energy simulations are generally consistent with those obtained at lower energies, two notable exceptions were observed. The first is that extensive subcascade formation at 40 keV leads to a higher defect survival fraction than would be predicted from extrapolation of the results obtained for energies up to 20 keV. The stable defect fraction obtained from the MD simulations is a smoothly decreasing function up to 20 keV. Subcascade formation leads to a slight increase in this ratio at 40 keV, where the value is about the same as at 10 keV. Secondly, the potential for a significant level of in-cascade vacancy clustering was observed. Previous cascade studies employing this potential have reported extensive interstitial clustering, but little evidence of vacancy clustering. Interstitial clusters were found to be strongly bound, with binding energies in excess of 1 eV. The larger clusters exhibited a complex, 3D structure and were composed of <111> crowdions. These clusters were observed to migrate by collective <111> translations with an activation energy on the order of 0.1 eV.

Minimally displaced clavicle fracture after high-energy injury: are they likely to displace?

PubMed

Riehl, John T; Athans, Bill J; Munro, Mark W; Langford, Joshua R; Kupiszewski, Stanley J; Haidukewych, George J; Koval, Kenneth J

2014-06-01

Nondisplaced or minimally displaced clavicle fractures are often considered to be benign injuries. These fractures in the trauma patient population, however, may deserve closer follow-up than their low-energy counterparts. We sought to determine the initial assessment performed on these patients and the rate of subsequent fracture displacement in patients sustaining high-energy trauma when a supine chest radiograph on initial trauma survey revealed a well-aligned clavicle fracture. We retrospectively reviewed the cases of trauma alert patients who sustained a midshaft clavicle fracture (AO/OTA type 15-B) with less than 100% displacement treated at a single level 1 trauma centre between 2005 and 2010. We compared fracture displacement on initial supine chest radiographs and follow-up radiographs. Orthopedic consultation and the type of imaging studies obtained were also recorded. Ninety-five patients with clavicle fractures met the inclusion criteria. On follow-up, 57 (60.0%) had displacement of 100% or more of the shaft width. Most patients (63.2%) in our study had an orthopedic consultation during their hospital admission, and 27.4% had clavicle radiographs taken on the day of admission. Clavicle fractures in patients with a high-energy mechanism of injury are prone to fracture displacement, even when initial supine chest radiographs show nondisplacement. We recommend clavicle films as part of the initial evaluation for all patients with clavicle fractures and early follow-up within the first 2 weeks of injury.

Minimally displaced clavicle fracture after high-energy injury: Are they likely to displace?

PubMed Central

Riehl, John T.; Athans, Bill J.; Munro, Mark W.; Langford, Joshua R.; Kupiszewski, Stanley J.; Haidukewych, George J.; Koval, Kenneth J.

2014-01-01

Background Nondisplaced or minimally displaced clavicle fractures are often considered to be benign injuries. These fractures in the trauma patient population, however, may deserve closer follow-up than their low-energy counterparts. We sought to determine the initial assessment performed on these patients and the rate of subsequent fracture displacement in patients sustaining high-energy trauma when a supine chest radiograph on initial trauma survey revealed a well-aligned clavicle fracture. Methods We retrospectively reviewed the cases of trauma alert patients who sustained a midshaft clavicle fracture (AO/OTA type 15-B) with less than 100% displacement treated at a single level 1 trauma centre between 2005 and 2010. We compared fracture displacement on initial supine chest radiographs and follow-up radiographs. Orthopedic consultation and the type of imaging studies obtained were also recorded. Results Ninety-five patients with clavicle fractures met the inclusion criteria. On follow-up, 57 (60.0%) had displacement of 100% or more of the shaft width. Most patients (63.2%) in our study had an orthopedic consultation during their hospital admission, and 27.4% had clavicle radiographs taken on the day of admission. Conclusion Clavicle fractures in patients with a high-energy mechanism of injury are prone to fracture displacement, even when initial supine chest radiographs show nondisplacement. We recommend clavicle films as part of the initial evaluation for all patients with clavicle fractures and early follow-up within the first 2 weeks of injury. PMID:24869608

Rugged Energy Landscapes in Multiphase Porous Media Flow: A Discrete-Domain Description

NASA Astrophysics Data System (ADS)

Cueto-Felgueroso, L.; Juanes, R.

2015-12-01

Immiscible displacements in porous media involve a complex sequence of pore-scale events, from the smooth, reversible displacement of interfaces to abrupt interfacial reconfigurations and rapid pore invasion cascades. Discontinuous changes in pressure or saturation have been referred to as Haines jumps, and they emerge as a key mechanism to understand the origin of hysteresis in porous media flow. Hysteresis persists at the many-pore scale: when multiple cycles of drainage and imbibition of a porous sample are conducted, a dense hysteresis diagram emerges. The interpretation of hysteresis as a consequence of irreversible transitions and multistability is at the heart of early hysteresis models, and in recent experiments, and points to an inherently non-equilibrium behavior. For a given volume fraction of fluids occupying the pore space, many stable configurations are possible, due to the tortuous network of nonuniform pores and throats that compose the porous medium, and to complex wetting and capillary transitions. Multistability indicates that porous media systems exhibit rugged energy landscapes, where the system may remain pinned at local energy minima for long times. We address the question of developing a zero-dimensional model that inherits the path-dependence and `'bursty'' behavior of immiscible displacements, and propose a discrete-domain model that captures the role of metastability and local equilibria in the origin of hysteresis. We describe the porous medium and fluid system as a discrete set of weakly connected, multistable compartments, charaterized by a unique free energy function. This description does not depend explicitly on past saturations, turning points, or drainage/imbibition labels. The system behaves hysteretically, and we rationalize its behavior as sweeping a complex metastability diagram, with dissipation arising from discrete switches among metastable branches. The hysteretic behavior of the pressure-saturation curve is controlled by the topography of the energy landscape, through the number of metastable regions of the compartments and characteristic height of the energy barriers separating the different basins. Our model opens the door to fully explore the interplay between hysteresis and fluctuations in multiphase displacements in porous media.

TU-CD-BRA-11: Application of Bone Suppression Technique to Inspiratory/expiratory Chest Radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, R; Sanada, S; Sakuta, K

Purpose: The bone suppression technique based on advanced image processing can suppress the conspicuity of bones on chest radiographs, creating soft tissue images normally obtained by the dual-energy subtraction technique. This study was performed to investigate the usefulness of bone suppression technique in quantitative analysis of pulmonary function in inspiratory/expiratory chest radiography. Methods: Commercial bone suppression image processing software (ClearRead; Riverain Technologies) was applied to paired inspiratory/expiratory chest radiographs of 107 patients (normal, 33; abnormal, 74) to create corresponding bone suppression images. The abnormal subjects had been diagnosed with pulmonary diseases, such as pneumothorax, pneumonia, emphysema, asthma, and lung cancer.more » After recognition of the lung area, the vectors of respiratory displacement were measured in all local lung areas using a cross-correlation technique. The measured displacement in each area was visualized as displacement color maps. The distribution pattern of respiratory displacement was assessed by comparison with the findings of lung scintigraphy. Results: Respiratory displacement of pulmonary markings (soft tissues) was able to be quantified separately from the rib movements on bone suppression images. The resulting displacement map showed a left-right symmetric distribution increasing from the lung apex to the bottom region of the lung in many cases. However, patients with ventilatory impairments showed a nonuniform distribution caused by decreased displacement of pulmonary markings, which were confirmed to correspond to area with ventilatory impairments found on the lung scintigrams. Conclusion: The bone suppression technique was useful for quantitative analysis of respiratory displacement of pulmonary markings without any interruption of the rib shadows. Abnormal areas could be detected as decreased displacement of pulmonary markings. Inspiratory/expiratory chest radiography combined with the bone suppression technique has potential for predicting local lung function on the basis of dynamic analysis of pulmonary markings. This work was partially supported by Nakatani Foundation, Grant-in-aid for Scientific Research (C) of Ministry of Education, Culture, Sports, Science and Technology, JAPAN (Grant number : 24601007), and Nakatani Foundation, Mitsubishi Foundation, and the he Mitani Foundation for Research and Development. Yasushi Kishitani is a staff of TOYO corporation.« less

Study on the Evaluation Method for Fault Displacement: Probabilistic Approach Based on Japanese Earthquake Rupture Data - Principal fault displacements -

NASA Astrophysics Data System (ADS)

Kitada, N.; Inoue, N.; Tonagi, M.

2016-12-01

The purpose of Probabilistic Fault Displacement Hazard Analysis (PFDHA) is estimate fault displacement values and its extent of the impact. There are two types of fault displacement related to the earthquake fault: principal fault displacement and distributed fault displacement. Distributed fault displacement should be evaluated in important facilities, such as Nuclear Installations. PFDHA estimates principal fault and distributed fault displacement. For estimation, PFDHA uses distance-displacement functions, which are constructed from field measurement data. We constructed slip distance relation of principal fault displacement based on Japanese strike and reverse slip earthquakes in order to apply to Japan area that of subduction field. However, observed displacement data are sparse, especially reverse faults. Takao et al. (2013) tried to estimate the relation using all type fault systems (reverse fault and strike slip fault). After Takao et al. (2013), several inland earthquakes were occurred in Japan, so in this time, we try to estimate distance-displacement functions each strike slip fault type and reverse fault type especially add new fault displacement data set. To normalized slip function data, several criteria were provided by several researchers. We normalized principal fault displacement data based on several methods and compared slip-distance functions. The normalized by total length of Japanese reverse fault data did not show particular trend slip distance relation. In the case of segmented data, the slip-distance relationship indicated similar trend as strike slip faults. We will also discuss the relation between principal fault displacement distributions with source fault character. According to slip distribution function (Petersen et al., 2011), strike slip fault type shows the ratio of normalized displacement are decreased toward to the edge of fault. However, the data set of Japanese strike slip fault data not so decrease in the end of the fault. This result indicates that the fault displacement is difficult to appear at the edge of the fault displacement in Japan. This research was part of the 2014-2015 research project `Development of evaluating method for fault displacement` by the Secretariat of Nuclear Regulation Authority (NRA), Japan.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xue, Haizhou; Zhang, Yanwen; Weber, William J.

Understanding how energy deposited in electronic and atomic subsystems may affect defect dynamics is a long-standing fundamental challenge in materials research. The coupling of displacement cascades and in-cascade ionization-induced annealing are investigated in silicon carbide (SiC). A delayed damage accumulation under ion irradiation is revealed with a linear dependence as a function of both increasing ionization and increasing ratio of electronic to nuclear energy deposition. An in-cascade healing mechanism is suggested with a low threshold value of electronic energy loss (~1.0 keV nm-1). The in-cascade ionization effects must be considered in predicting radiation performance of SiC.

Proton Nonionizing Energy Loss (NIEL) for Device Applications

NASA Technical Reports Server (NTRS)

Jun, Insoo; Xapsos, Michael A.; Messenger, Scott R.; Burke, Edward A.; Walters, Robert J.; Summers, Geoff; Jordan, Thomas

2003-01-01

Nonionizing energy loss (NIEL) is a quantity that describes the rate of energy loss due to atomic displacements as a particle traverses a material. The product of the NIEL and the particle fluence (time integrated flux) gives the displacement damage energy deposition per unit mass of material. NIEL plays the same role to the displacement damage energy deposition as the stopping power to the total ionizing dose (TID). The concept of NIEL has been very useful for correlating particle induced displacement damage effects in semiconductor and optical devices. Many studies have successfully demonstrated that the degradation of semiconductor devices or optical sensors in a radiation field can be linearly correlated to the displacement damage energy, and subsequently to the NIEL deposited in the semiconductor devices or optical sensors. In addition, the NIEL concept was also useful in the study of both Si and GaAs solar cells and of high temperature superconductors, and at predicting the survivability of detectors used at the LHC at CERN. On the other hand, there are some instances where discrepancies are observed in the application of NIEL, most notably in GaAs semiconductor devices. However, NIEL is still a valuable tool, and can be used to scale damages produced by different particles and in different environments, even though this is not understood at the microscopic level.

Characterization of piezoelectric device for implanted pacemaker energy harvesting

NASA Astrophysics Data System (ADS)

Jay, Sunny; Caballero, Manuel; Quinn, William; Barrett, John; Hill, Martin

2016-10-01

Novel implanted cardiac pacemakers that are powered by energy harvesters driven by the cardiac motion and have a 40 year lifetime are currently under development. To satisfy space constraints and energy requirements of the device, silicon-based MEMS energy harvesters are being developed in the EU project (MANpower1). Such MEMS harvesters for vibration frequencies below 50 Hz have not been widely reported. In this paper, an analytical model and a 3D finite element model (FEM) to predict displacement and open circuit voltage, validated through experimental analysis using an off-the-shelf low frequency energy harvester, are presented. The harvester was excited through constant amplitude sinusoidal base displacement over a range of 20 to 70 Hz passing through its first mode natural frequency at 47 Hz. At resonance both models predict displacements with an error of less than 2% when compared to the experimental result. Comparing the two models, the application of the experimentally measured damping ratio differs for accurate displacement prediction and the differences in symmetry in the measured and modelled displacement and voltage data around the resonance frequency indicate the two piezoelectric voltage models use different fundamental equations.

In situ disordering of monoclinic titanium monoxide Ti5O5 studied by transmission electron microscope TEM.

PubMed

Rempel, А А; Van Renterghem, W; Valeeva, А А; Verwerft, M; Van den Berghe, S

2017-09-07

The superlattice and domain structures exhibited by ordered titanium monoxide Ti 5 O 5 are disrupted by low energy electron beam irradiation. The effect is attributed to the disordering of the oxygen and titanium sublattices. This disordering is caused by the displacement of both oxygen and titanium atoms by the incident electrons and results in a phase transformation of the monoclinic phase Ti 5 O 5 into cubic B1 titanium monoxide. In order to determine the energies required for the displacement of titanium or oxygen atoms, i.e. threshold displacement energies, a systematic study of the disappearance of superstructure reflections with increasing electron energy and electron bombardment dose has been performed in situ in a transmission electron microscope (TEM). An incident electron energy threshold between 120 and 140 keV has been observed. This threshold can be ascribed to the displacements of titanium atoms with 4 as well as with 5 oxygen atoms as nearest neighbors. The displacement threshold energy of titanium atoms in Ti 5 O 5 corresponding with the observed incident electron threshold energy lies between 6.0 and 7.5 eV. This surprisingly low value can be explained by the presence of either one or two vacant oxygen lattice sites in the nearest neighbors of all titanium atoms.

Impact of Multifunctional Bimetallic Materials on Lithium Battery Electrochemistry.

PubMed

Durham, Jessica L; Poyraz, Altug S; Takeuchi, Esther S; Marschilok, Amy C; Takeuchi, Kenneth J

2016-09-20

Electric energy storage devices such as batteries are complex systems comprised of a variety of materials with each playing separate yet interactive roles, complicated by length scale interactions occurring from the molecular to the mesoscale. Thus, addressing specific battery issues such as functional capacity requires a comprehensive perspective initiating with atomic level concepts. For example, the electroactive materials which contribute to the functional capacity in a battery comprise approximately 30% or less of the total device mass. Thus, the design and implementation of multifunctional materials can conceptually reduce or eliminate the contribution of passive materials to the size and mass of the final system. Material multifunctionality can be achieved through appropriate material design on the atomic level resulting in bimetallic electroactive materials where one metal cation forms mesoscale conductive networks upon discharge while the other metal cations can contribute to atomic level structure and net functional secondary capacity, a device level issue. Specifically, this Account provides insight into the multimechanism electrochemical redox processes of bimetallic cathode materials based on transition metal oxides (MM'O) or phosphorus oxides (MM'PO) where M = Ag and M' = V or Fe. One discharge process can be described as reduction-displacement where Ag(+) is reduced to Ag(0) and displaced from the parent structure. This reduction-displacement reaction in silver-containing bimetallic electrodes allows for the in situ formation of a conductive network, enhancing the electrochemical performance of the electrode and reducing or eliminating the need for conductive additives. A second discharge process occurs through the reduction of the second transition metal, V or Fe, where the oxidation state of the metal center is reduced and lithium cations are inserted into the structure. As both metal centers contribute to the functional capacity, determining the kinetically and thermodynamically preferred reduction processes at various states of discharge is critical to elucidating the mechanism. Specific advanced in situ and ex situ characterization techniques are conducive to gaining insight regarding the electrochemical behavior of these multifunctional materials over multiple length scales. At the material level, optical microscopy, scanning electron microscopy, and local conductivity measurement via a nanoprobe can track the discharge mechanism of an isolated single particle. At the mesoscale electrode level, in situ data from synchrotron based energy dispersive X-ray diffraction (EDXRD) within fully intact steel batteries can be used to spatially map the distribution of silver metal generated through reduction displacement as a function of discharge depth and discharge rate. As illustrated here, appropriate design of materials with multiple electrochemically active metal centers and properties tuned through strategically conceptualized materials synthesis may provide a path toward the next generation of high energy content electroactive materials and systems. Full understanding of the multiple electrochemical mechanisms can be achieved only by utilizing advanced characterization tools over multiple length scales.

First-Principles Investigation of Radiation Induced Defects in SiC and Si.

NASA Astrophysics Data System (ADS)

Windl, Wolfgang; Lenosky, Thomas J.; Kress, Joel D.; Voter, Arthur F.

1997-03-01

SiC shows promise as a structural material for fusion reactors, partly because of its low activation under neutron irradiation. This radiation, however, can cause damage to its crystal structure, thereby degrading its properties. The focus of this work is the understanding of this neutron-induced radiation damage to SiC. Neutrons interact with matter primarily by scattering off nuclei, an event which suddenly imparts energy and momentum to an atom. If enough energy is transferred, this scattering event creates structural damage, such as displacement of the impacted atom from its original position to an interstitial site. We performed quantum molecular dynamics simulations to determine the displacement energy threshold, i.e., the minimum energy transfer required to create damage. To do this, we used the self-consistent Demkov-Ortega-Grumbach-Sankey (DOGS) extension(A. A. Demkov et al.), Phys. Rev. B 52, 1618 (1995). of the Harris-functional local orbital LDA method of Sankey et al. In order to benchmark the quality of our methodology for studying radiation damage, we compare our results to those of calculations employing classical interatomic potentials; furthermore, we performed similar simulations for Si, where experimental data exist.

Shape fluctuations of nearly spherical lipid vesicles and emulsion droplets.

PubMed

Bivas, Isak

2010-06-01

It is known that the relaxation of the shape fluctuations of nearly spherical lipid vesicles is accompanied by a lateral displacement of the monolayers, comprising their bilayers. In this work a dissipation mechanism of the mechanical energy stored in the fluctuation is revealed that concerns the viscous friction of the flow in the liquid around the vesicle caused by this displacement. The time correlation functions of each of the vesicle's fluctuation modes are calculated as a function of the mechanical and rheological properties of the system which are the tension of the vesicle bilayer, its bending elasticities at free and blocked flip-flop, the viscosities of the liquids bathing the bilayer, the friction coefficient between the two monolayers, as well as the vesicle's dimensions: its bilayer thickness and radius. The correlations of the shape fluctuations of nearly spherical emulsion droplets are also calculated for different viscosities of the liquid inside and outside the droplet.

Improved operation of magnetic bearings for flywheel energy storage system

NASA Technical Reports Server (NTRS)

Zmood, R. B.; Pang, D.; Anand, D. K.; Kirk, J. A.

1990-01-01

Analysis and operation of prototype 500-Wh flywheel at low speeds have shown that many factors affect the correct functioning of the magnetic bearings. An examination is made of a number of these, including magnetic bearing control system nonlinearities and displacement transducer positioning, and their effects upon the successful operation of the suspension system. It is observed that the bearing control system is extremely sensitive to actuator parameters such as coil inductance. As a consequence of the analysis of bearing relaxation oscillations, the bearing actuator design methodology which has previously been used, where coil parameter selection is based upon static considerations, has been revised. Displacement transducer sensors which overcome the collocation problem are discussed.

Approximation of a Brittle Fracture Energy with a Constraint of Non-interpenetration

NASA Astrophysics Data System (ADS)

Chambolle, Antonin; Conti, Sergio; Francfort, Gilles A.

2018-06-01

Linear fracture mechanics (or at least the initiation part of that theory) can be framed in a variational context as a minimization problem over an SBD type space. The corresponding functional can in turn be approximated in the sense of {Γ}-convergence by a sequence of functionals involving a phase field as well as the displacement field. We show that a similar approximation persists if additionally imposing a non-interpenetration constraint in the minimization, namely that only nonnegative normal jumps should be permissible.

Increasing Accuracy of Tissue Shear Modulus Reconstruction Using Ultrasonic Strain Tensor Measurement

NASA Astrophysics Data System (ADS)

Sumi, C.

Previously, we developed three displacement vector measurement methods, i.e., the multidimensional cross-spectrum phase gradient method (MCSPGM), the multidimensional autocorrelation method (MAM), and the multidimensional Doppler method (MDM). To increase the accuracies and stabilities of lateral and elevational displacement measurements, we also developed spatially variant, displacement component-dependent regularization. In particular, the regularization of only the lateral/elevational displacements is advantageous for the lateral unmodulated case. The demonstrated measurements of the displacement vector distributions in experiments using an inhomogeneous shear modulus agar phantom confirm that displacement-component-dependent regularization enables more stable shear modulus reconstruction. In this report, we also review our developed lateral modulation methods that use Parabolic functions, Hanning windows, and Gaussian functions in the apodization function and the optimized apodization function that realizes the designed point spread function (PSF). The modulations significantly increase the accuracy of the strain tensor measurement and shear modulus reconstruction (demonstrated using an agar phantom).

A Monte Carlo simulation code for calculating damage and particle transport in solids: The case for electron-bombarded solids for electron energies up to 900 MeV

NASA Astrophysics Data System (ADS)

Yan, Qiang; Shao, Lin

2017-03-01

Current popular Monte Carlo simulation codes for simulating electron bombardment in solids focus primarily on electron trajectories, instead of electron-induced displacements. Here we report a Monte Carol simulation code, DEEPER (damage creation and particle transport in matter), developed for calculating 3-D distributions of displacements produced by electrons of incident energies up to 900 MeV. Electron elastic scattering is calculated by using full-Mott cross sections for high accuracy, and primary-knock-on-atoms (PKAs)-induced damage cascades are modeled using ZBL potential. We compare and show large differences in 3-D distributions of displacements and electrons in electron-irradiated Fe. The distributions of total displacements are similar to that of PKAs at low electron energies. But they are substantially different for higher energy electrons due to the shifting of PKA energy spectra towards higher energies. The study is important to evaluate electron-induced radiation damage, for the applications using high flux electron beams to intentionally introduce defects and using an electron analysis beam for microstructural characterization of nuclear materials.

Nature of the octahedral tilting phase transitions in perovskites: A case study of CaMnO3

NASA Astrophysics Data System (ADS)

Klarbring, Johan; Simak, Sergei I.

2018-01-01

The temperature-induced antiferrodistortive (AFD) structural phase transitions in CaMnO3, a typical perovskite oxide, are studied using first-principles density functional theory calculations. These transitions are caused by tilting of the MnO6 octahedra that are related to unstable phonon modes in the high-symmetry cubic perovskite phase. Transitions due to octahedral tilting in perovskites normally are believed to fit into the standard soft-mode picture of displacive phase transitions. We calculate phonon-dispersion relations and potential-energy landscapes as functions of the unstable phonon modes and argue based on the results that the phase transitions are better described as being of order-disorder type. This means that the cubic phase emerges as a dynamical average when the system hops between local minima on the potential-energy surface. We then perform ab initio molecular dynamics simulations and find explicit evidence of the order-disorder dynamics in the system. Our conclusions are expected to be valid for other perovskite oxides, and we finally suggest how to predict the nature (displacive or order-disorder) of the AFD phase transitions in any perovskite system.

30 CFR 1206.356 - How do I calculate royalty or fees due on geothermal resources I use for direct use purposes?

Code of Federal Regulations, 2012 CFR

2012-07-01

... energy source will be based on the amount of thermal energy that would otherwise be used by the direct use facility in place of the geothermal resource. That amount of thermal energy (in Btu) displaced by... frequency of computing and accumulating the amount of thermal energy displaced will be determined and...

30 CFR 1206.356 - How do I calculate royalty or fees due on geothermal resources I use for direct use purposes?

Code of Federal Regulations, 2013 CFR

2013-07-01

... energy source will be based on the amount of thermal energy that would otherwise be used by the direct use facility in place of the geothermal resource. That amount of thermal energy (in Btu) displaced by... frequency of computing and accumulating the amount of thermal energy displaced will be determined and...

30 CFR 1206.356 - How do I calculate royalty or fees due on geothermal resources I use for direct use purposes?

Code of Federal Regulations, 2014 CFR

2014-07-01

... energy source will be based on the amount of thermal energy that would otherwise be used by the direct use facility in place of the geothermal resource. That amount of thermal energy (in Btu) displaced by... frequency of computing and accumulating the amount of thermal energy displaced will be determined and...

Impact of Multifunctional Bimetallic Materials on Lithium Battery Electrochemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Durham, Jessica L.; Poyraz, Altug S.; Takeuchi, Esther S.

Electric energy storage devices such as batteries are complex systems comprised of a variety of materials with each playing separate yet interactive roles, complicated by length scale interactions occurring from the molecular to the mesoscale. Thus, addressing specific battery issues such as functional capacity requires a comprehensive perspective initiating with atomic level concepts. For example, the electroactive materials which contribute to the functional capacity in a battery comprise approximately 30% or less of the total device mass. Thus, the design and implementation of multifunctional materials can conceptually reduce or eliminate the contribution of passive materials to the size and massmore » of the final system. Material multi-functionality can be achieved through appropriate material design on the atomic level resulting in bimetallic electroactive materials where one metal cation forms mesoscale conductive networks upon discharge while the other metal cation can contribute to atomic level structure and net functional secondary capacity, a device level issue. Specifically, this Account provides insight into the multi-mechanism electrochemical redox processes of bimetallic cathode materials based on transition metal oxides (MM’O) or phosphorous oxides (MM’PO) where M = Ag and M’ = V or Fe. One discharge process can be described as reduction-displacement where Ag + is reduced to Ag 0 and displaced from the parent structure. This reduction-displacement reaction in silver-containing bimetallic electrodes allows for the in-situ formation of a conductive network, enhancing the electrochemical performance of the electrode and reducing or eliminating the need for conductive additives. A second discharge process occurs through the reduction of the second transition metal, V or Fe, where the oxidation state of the metal center is reduced and lithium cations are inserted into the structure. As both metal centers contribute to the functional capacity, determining the kinetically and thermodynamically preferred reduction processes at various states of discharge is critical to elucidating the mechanism. Specific advanced in-situ and ex-situ characterization techniques are conducive to gaining insight regarding the electrochemical behavior of these multifunctional materials over multiple length scales. At the material level, optical microscopy, scanning electron microscopy, and local conductivity measurement via a nanoprobe can track the discharge mechanism of an isolated single particle. At the mesoscale electrode level, in-situ data from synchrotron based energy dispersive X-ray diffraction (EDXRD) within fully intact steel batteries can be used to spatially map the distribution of silver metal generated through reduction displacement as a function of discharge depth and discharge rate. As illustrated here, appropriate design of materials with multiple electrochemically active metal centers and properties tuned through strategically conceptualized materials synthesis may provide a path toward the next generation of high energy content electroactive materials and systems. In conclusion, full understanding of the multiple electrochemical mechanisms can be achieved only by utilizing advanced characterization tools over multiple length scales.« less

Impact of Multifunctional Bimetallic Materials on Lithium Battery Electrochemistry

DOE PAGES

Durham, Jessica L.; Poyraz, Altug S.; Takeuchi, Esther S.; ...

2016-08-26

Electric energy storage devices such as batteries are complex systems comprised of a variety of materials with each playing separate yet interactive roles, complicated by length scale interactions occurring from the molecular to the mesoscale. Thus, addressing specific battery issues such as functional capacity requires a comprehensive perspective initiating with atomic level concepts. For example, the electroactive materials which contribute to the functional capacity in a battery comprise approximately 30% or less of the total device mass. Thus, the design and implementation of multifunctional materials can conceptually reduce or eliminate the contribution of passive materials to the size and massmore » of the final system. Material multi-functionality can be achieved through appropriate material design on the atomic level resulting in bimetallic electroactive materials where one metal cation forms mesoscale conductive networks upon discharge while the other metal cation can contribute to atomic level structure and net functional secondary capacity, a device level issue. Specifically, this Account provides insight into the multi-mechanism electrochemical redox processes of bimetallic cathode materials based on transition metal oxides (MM’O) or phosphorous oxides (MM’PO) where M = Ag and M’ = V or Fe. One discharge process can be described as reduction-displacement where Ag + is reduced to Ag 0 and displaced from the parent structure. This reduction-displacement reaction in silver-containing bimetallic electrodes allows for the in-situ formation of a conductive network, enhancing the electrochemical performance of the electrode and reducing or eliminating the need for conductive additives. A second discharge process occurs through the reduction of the second transition metal, V or Fe, where the oxidation state of the metal center is reduced and lithium cations are inserted into the structure. As both metal centers contribute to the functional capacity, determining the kinetically and thermodynamically preferred reduction processes at various states of discharge is critical to elucidating the mechanism. Specific advanced in-situ and ex-situ characterization techniques are conducive to gaining insight regarding the electrochemical behavior of these multifunctional materials over multiple length scales. At the material level, optical microscopy, scanning electron microscopy, and local conductivity measurement via a nanoprobe can track the discharge mechanism of an isolated single particle. At the mesoscale electrode level, in-situ data from synchrotron based energy dispersive X-ray diffraction (EDXRD) within fully intact steel batteries can be used to spatially map the distribution of silver metal generated through reduction displacement as a function of discharge depth and discharge rate. As illustrated here, appropriate design of materials with multiple electrochemically active metal centers and properties tuned through strategically conceptualized materials synthesis may provide a path toward the next generation of high energy content electroactive materials and systems. In conclusion, full understanding of the multiple electrochemical mechanisms can be achieved only by utilizing advanced characterization tools over multiple length scales.« less

Heisenberg limit for displacements with semiclassical states

NASA Astrophysics Data System (ADS)

Luis, Alfredo

2004-04-01

We analyze the quantum limit to the sensitivity of the detection of small displacements. We focus on the case of free particles and harmonic oscillators as the systems experiencing the displacement. We show that the minimum displacement detectable is proportional to the inverse of the square root of the mean value of the energy in the state experiencing the displacement (Heisenberg limit). We present a measuring scheme that reaches this limit using semiclassical states. We examine the performance of this strategy under realistic practical conditions by computing the effect of imperfections such as losses and nonunit detection efficiencies. This analysis confirms the robustness of this measuring strategy by showing that the experimental imperfections can be suitably compensated by increasing the mean energy of the input state.

The (Possibly Negative) Effects of Physical Activity on Executive Functions: Implications of the Changing Metabolic Costs of Brain Development.

PubMed

Howard, Steven J; Cook, Caylee J; Said-Mohamed, Rihlat; Norris, Shane A; Draper, Catherine E

2016-09-01

An area of growth in physical activity research has involved investigating effects of physical activity on children's executive functions. Many of these efforts seek to increase the energy expenditure of young children as a healthy and low-cost way to affect physical, health, and cognitive outcomes. We review theory and research from neuroscience and evolutionary biology, which suggest that interventions seeking to increase the energy expenditure of young children must also consider the energetic trade-offs that occur to accommodate changing metabolic costs of brain development. According to Life History Theory, and supported by recent evidence, the high relative energy-cost of early brain development requires that other energy-demanding functions of development (ie, physical growth, activity) be curtailed. This is important for interventions seeking to dramatically increase the energy expenditure of young children who have little excess energy available, with potentially negative cognitive consequences. Less energy-demanding physical activities, in contrast, may yield psychosocial and cognitive benefits while not overburdening an underweight child's already scarce energy supply. While further research is required to establish the extent to which increases in energy-demanding physical activities may compromise or displace energy available for brain development, we argue that action cannot await these findings.

Programmable energy landscapes for kinetic control of DNA strand displacement.

PubMed

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.

An assessment of the industrial cogeneration market for parabolic dish systems

NASA Technical Reports Server (NTRS)

Doane, J. W.

1981-01-01

The value analysis technique used is straightforward. Maximum allowable life-cycle system cost for the cogeneration system is determined as the sum of the present value of fuels displaced plus the present value of revenues from exported power. Each conventional fuel displaced is described by a unit cost in the first year, a uniform annual consumption rate, and a uniform annual escalation rate for unit cost. Exported energy flows are treated the same as displaced energy.

Ab initio and Molecular Dynamic models of displacement damage in crystalline and turbostratic graphite

NASA Astrophysics Data System (ADS)

McKenna, Alice

One of the functions of graphite is as a moderator in several nuclear reactor designs, including the Advanced Gas-cooled Reactor (AGR). In the reactor graphite is used to thermalise the neutrons produced in the fission reaction thus allowing a self-sustained reaction to occur. The graphite blocks, acting as the moderator, are constantly irradiated and consequently suffer damage. This thesis examines the types of damage caused using molecular dynamic (MD) simulations and ab intio calculations. Neutron damage starts with a primary knock-on atom (PKA), which is travelling so fast that it creates damage through electronic and thermal excitation (this is addressed with thermal spike simulations). When the PKA has lost energy the subsequent cascade is based on ballistic atomic displacement. These two types of simulations were performed on single crystal graphite and other carbon structures such as diamond and amorphous carbon as a comparison. The thermal spike in single crystal graphite produced results which varied from no defects to a small number of permanent defects in the structure. It is only at the high energy range that more damage is seen but these energies are less likely to occur in the nuclear reactor. The thermal spike does not create damage but it is possible that it can heal damaged sections of the graphite, which can be demonstrated with the motion of the defects when a thermal spike is applied. The cascade simulations create more damage than the thermal spike even though less energy is applied to the system. A new damage function is found with a threshold region that varies with the square root of energy in excess of the energy threshold. This is further broken down in to contributions from primary and subsequent knock-on atoms. The threshold displacement energy (TDE) is found to be Ed=25eV at 300K. In both these types of simulation graphite acts very differently to the other carbon structures. There are two types of polycrystalline graphite structures which simulations have been performed on. The difference between the two is at the grain boundaries with one having dangling bonds and the other one being bonded. The cascade showed the grain boundaries acting as a trap for the knock-on atoms which produces more damage compared with the single crystal. Finally the effects of turbostratic disorder on damage is considered. Density functional theory (DFT) was used to look at interstitials in (002) twist boundaries and how they act compared to AB stacked graphite. The results of these calculations show that the spiro interstitial is more stable in these grain boundaries, so at temperatures where the interstitial can migrate along the c direction they will segregate to (002) twist boundaries.

A new method to approximate load-displacement relationships of spinal motion segments for patient-specific multi-body models of scoliotic spine.

PubMed

Jalalian, Athena; Tay, Francis E H; Arastehfar, Soheil; Liu, Gabriel

2017-06-01

Load-displacement relationships of spinal motion segments are crucial factors in characterizing the stiffness of scoliotic spine models to mimic the spine responses to loads. Although nonlinear approach to approximation of the relationships can be superior to linear ones, little mention has been made to deriving personalized nonlinear load-displacement relationships in previous studies. A method is developed for nonlinear approximation of load-displacement relationships of spinal motion segments to assist characterizing in vivo the stiffness of spine models. We propose approximation by tangent functions and focus on rotational displacements in lateral direction. The tangent functions are characterized using lateral bending test. A multi-body model was characterized to 18 patients and utilized to simulate four spine positions; right bending, left bending, neutral, and traction. The same was done using linear functions to assess the performance of the proposed tangent function in comparison with the linear function. Root-mean-square error (RMSE) of the displacements estimated by the tangent functions was 44 % smaller than the linear functions. This shows the ability of our tangent function in approximation of the relationships for a range of infinitesimal to large displacements involved in the spine movement to the four positions. In addition, the models based on the tangent functions yielded 67, 55, and 39 % smaller RMSEs of Ferguson angles, locations of vertebrae, and orientations of vertebrae, respectively, implying better estimates of spine responses to loads. Overall, it can be concluded that our method for approximating load-displacement relationships of spinal motion segments can offer good estimates of scoliotic spine stiffness.

Hartree-Fock theory of the inhomogeneous electron gas at a jellium metal surface: Rigorous upper bounds to the surface energy and accurate work functions

NASA Astrophysics Data System (ADS)

Sahni, V.; Ma, C. Q.

1980-12-01

The inhomogeneous electron gas at a jellium metal surface is studied in the Hartree-Fock approximation by Kohn-Sham density functional theory. Rigorous upper bounds to the surface energy are derived by application of the Rayleigh-Ritz variational principle for the energy, the surface kinetic, electrostatic, and nonlocal exchange energy functionals being determined exactly for the accurate linear-potential model electronic wave functions. The densities obtained by the energy minimization constraint are then employed to determine work-function results via the variationally accurate "displaced-profile change-in-self-consistent-field" expression. The theoretical basis of this non-self-consistent procedure and its demonstrated accuracy for the fully correlated system (as treated within the local-density approximation for exchange and correlation) leads us to conclude these results for the surface energies and work functions to be essentially exact. Work-function values are also determined by the Koopmans'-theorem expression, both for these densities as well as for those obtained by satisfaction of the constraint set on the electrostatic potential by the Budd-Vannimenus theorem. The use of the Hartree-Fock results in the accurate estimation of correlation-effect contributions to these surface properties of the nonuniform electron gas is also indicated. In addition, the original work and approximations made by Bardeen in this attempt at a solution of the Hartree-Fock problem are briefly reviewed in order to contrast with the present work.

Energy compensation and nutrient displacement following regular consumption of hazelnuts and other energy-dense snack foods in non-obese individuals.

PubMed

Pearson, Katherine R; Tey, Siew Ling; Gray, Andrew R; Chisholm, Alexandra; Brown, Rachel C

2017-04-01

Regular nut consumption reduces cardiovascular disease risk, partly from improvements to dietary quality. Examining how individuals make dietary changes when consuming nuts may reveal key behavioural eating patterns beneficial for the development of dietary interventions. We examined the effects of nuts in comparison with other energy-dense snacks on energy compensation, nutrient displacement, and food group patterns. This was a 12-week randomised, controlled, parallel study with four arms: ~1100 kJ/day for each of hazelnuts (42 g), chocolate (50 g), potato crisps (50 g), or no added snack food. Diet records, body composition, and physical activity were measured at baseline and week 12, in 102 non-obese participants. Significant improvements in diet quality were observed in the hazelnut group, particularly when consumed as snacks. Intakes of monounsaturated fat (MUFA) and vitamin E were significantly higher (all P < 0.05), whereas saturated fat and carbohydrate were significantly lower (both P ≤ 0.022) in the hazelnut group compared to the other groups. Partial energy compensation did not differ significantly between groups, but nutrient displacement values for MUFA and fibre differed significantly. Within the hazelnut group, there was nearly complete displacement for fibre, partial displacement for energy, protein, total fat, MUFA, PUFA, potassium, folate, and vitamin E, and overcompensation for carbohydrate and sugar. Our results demonstrate that energy compensation occurs for all three intervention snacks in this non-obese population. Regular nut consumption significantly improves nutrient profiles compared to other snacks with changes occurring at the snack level.

A study of planar anchor groups for graphene-based single-molecule electronics.

PubMed

Bailey, Steven; Visontai, David; Lambert, Colin J; Bryce, Martin R; Frampton, Harry; Chappell, David

2014-02-07

To identify families of stable planar anchor groups for use in single molecule electronics, we report detailed results for the binding energies of two families of anthracene and pyrene derivatives adsorbed onto graphene. We find that all the selected derivatives functionalized with either electron donating or electron accepting substituents bind more strongly to graphene than the parent non-functionalized anthracene or pyrene. The binding energy is sensitive to the detailed atomic alignment of substituent groups over the graphene substrate leading to larger than expected binding energies for -OH and -CN derivatives. Furthermore, the ordering of the binding energies within the anthracene and pyrene series does not simply follow the electron affinities of the substituents. Energy barriers to rotation or displacement on the graphene surface are much lower than binding energies for adsorption and therefore at room temperature, although the molecules are bound to the graphene, they are almost free to move along the graphene surface. Binding energies can be increased by incorporating electrically inert side chains and are sensitive to the conformation of such chains.

A study of planar anchor groups for graphene-based single-molecule electronics

NASA Astrophysics Data System (ADS)

Bailey, Steven; Visontai, David; Lambert, Colin J.; Bryce, Martin R.; Frampton, Harry; Chappell, David

2014-02-01

To identify families of stable planar anchor groups for use in single molecule electronics, we report detailed results for the binding energies of two families of anthracene and pyrene derivatives adsorbed onto graphene. We find that all the selected derivatives functionalized with either electron donating or electron accepting substituents bind more strongly to graphene than the parent non-functionalized anthracene or pyrene. The binding energy is sensitive to the detailed atomic alignment of substituent groups over the graphene substrate leading to larger than expected binding energies for -OH and -CN derivatives. Furthermore, the ordering of the binding energies within the anthracene and pyrene series does not simply follow the electron affinities of the substituents. Energy barriers to rotation or displacement on the graphene surface are much lower than binding energies for adsorption and therefore at room temperature, although the molecules are bound to the graphene, they are almost free to move along the graphene surface. Binding energies can be increased by incorporating electrically inert side chains and are sensitive to the conformation of such chains.

Toward tunable band gap and tunable dirac point in bilayer graphene with molecular doping.

PubMed

Yu, Woo Jong; Liao, Lei; Chae, Sang Hoon; Lee, Young Hee; Duan, Xiangfeng

2011-11-09

The bilayer graphene has attracted considerable attention for potential applications in future electronics and optoelectronics because of the feasibility to tune its band gap with a vertical displacement field to break the inversion symmetry. Surface chemical doping in bilayer graphene can induce an additional offset voltage to fundamentally affect the vertical displacement field and the band gap opening in bilayer graphene. In this study, we investigate the effect of chemical molecular doping on band gap opening in bilayer graphene devices with single or dual gate modulation. Chemical doping with benzyl viologen molecules modulates the displacement field to allow the opening of a transport band gap and the increase of the on/off ratio in the bilayer graphene transistors. Additionally, Fermi energy level in the opened gap can be rationally controlled by the amount of molecular doping to obtain bilayer graphene transistors with tunable Dirac points, which can be readily configured into functional devices, such as complementary inverters.

Silicon displacement threshold energy determined by electron paramagnetic resonance and positron annihilation spectroscopy in cubic and hexagonal polytypes of silicon carbide

NASA Astrophysics Data System (ADS)

Kerbiriou, X.; Barthe, M.-F.; Esnouf, S.; Desgardin, P.; Blondiaux, G.; Petite, G.

2007-05-01

Both for electronic and nuclear applications, it is of major interest to understand the properties of point defects into silicon carbide (SiC). Low energy electron irradiations are supposed to create primary defects into materials. SiC single crystals have been irradiated with electrons at two beam energies in order to investigate the silicon displacement threshold energy into SiC. This paper presents the characterization of the electron irradiation-induced point defects into both polytypes hexagonal (6H) and cubic (3C) SiC single crystals by using both positron annihilation spectroscopy (PAS) and electron paramagnetic resonance (EPR). The nature and the concentration of the generated point defects depend on the energy of the electron beam and the polytype. After an electron irradiation at an energy of 800 keV vSi mono-vacancies and vSi-vC di-vacancies are detected in both 3C and 6H-SiC polytypes. On the contrary, the nature of point defects detected after an electron irradiation at 190 keV strongly depends on the polytype. Into 6H-SiC crystals, silicon Frenkel pairs vSi-Si are detected whereas only carbon vacancy related defects are detected into 3C-SiC crystals. The difference observed in the distribution of defects detected into the two polytypes can be explained by the different values of the silicon displacement threshold energies for 3C and 6H-SiC. By comparing the calculated theoretical numbers of displaced atoms with the defects numbers measured using EPR, the silicon displacement threshold energy has been estimated to be slightly lower than 20 eV in the 6H polytype and close to 25 eV in the 3C polytype.

Improved Displacement Transfer Functions for Structure Deformed Shape Predictions Using Discretely Distributed Surface Strains

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2012-01-01

In the formulations of earlier Displacement Transfer Functions for structure shape predictions, the surface strain distributions, along a strain-sensing line, were represented with piecewise linear functions. To improve the shape-prediction accuracies, Improved Displacement Transfer Functions were formulated using piecewise nonlinear strain representations. Through discretization of an embedded beam (depth-wise cross section of a structure along a strain-sensing line) into multiple small domains, piecewise nonlinear functions were used to describe the surface strain distributions along the discretized embedded beam. Such piecewise approach enabled the piecewise integrations of the embedded beam curvature equations to yield slope and deflection equations in recursive forms. The resulting Improved Displacement Transfer Functions, written in summation forms, were expressed in terms of beam geometrical parameters and surface strains along the strain-sensing line. By feeding the surface strains into the Improved Displacement Transfer Functions, structural deflections could be calculated at multiple points for mapping out the overall structural deformed shapes for visual display. The shape-prediction accuracies of the Improved Displacement Transfer Functions were then examined in view of finite-element-calculated deflections using different tapered cantilever tubular beams. It was found that by using the piecewise nonlinear strain representations, the shape-prediction accuracies could be greatly improved, especially for highly-tapered cantilever tubular beams.

Comparing Life-Cycle Carbon and Energy Impacts for Biofuel, Wood Product, and Forest Management

Treesearch

Bruce Lippke; Richard Gustafson; Richard Venditti; Philip Steele; Timothy A. Volk; Elaine Oneil; Leonard Johnson; Maureen E. Puettmann; Kenneth Skog

2012-01-01

The different uses of wood result in a hierarchy of carbon and energy impacts that can be characterized by their efficiency in displacing carbon emissions and/or in displacing fossil energy imports, both being current national objectives. When waste wood is used for biofuels (forest or mill residuals and thinnings) fossil fuels and their emissions are reduced without...

Coulomb displacement energies of excited states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sherr, R.; Bertsch, G.

The Bansal--French--Zamick model is quite successful in accounting for the Coulomb displacement energies of excited particle--hole states in a variety of light nuclei. Level shifts are typically reproduced to within 50 keV. However, the model fails for certain excited 0$sup +$ states, and this remains a puzzle. (AIP)

Calculation of Stress Intensity Factors for Interfacial Cracks in Fiber Metal Laminates

NASA Technical Reports Server (NTRS)

Wang, John T.

2009-01-01

Stress intensity factors for interfacial cracks in Fiber Metal Laminates (FML) are computed by using the displacement ratio method recently developed by Sun and Qian (1997, Int. J. Solids. Struct. 34, 2595-2609). Various FML configurations with single and multiple delaminations subjected to different loading conditions are investigated. The displacement ratio method requires the total energy release rate, bimaterial parameters, and relative crack surface displacements as input. Details of generating the energy release rates, defining bimaterial parameters with anisotropic elasticity, and selecting proper crack surface locations for obtaining relative crack surface displacements are discussed in the paper. Even though the individual energy release rates are nonconvergent, mesh-size-independent stress intensity factors can be obtained. This study also finds that the selection of reference length can affect the magnitudes and the mode mixity angles of the stress intensity factors; thus, it is important to report the reference length used with the calculated stress intensity factors.

Apparatus for the conversion of power strokes of a random sequence and of random lengths of strokes into potential energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elkuch, E.

1984-01-17

The apparatus comprises at least one positive displacement pump, which is driven by the sea waves. The quantity of delivery of this pump is adjustable in accordance with the lengths of strokes made by the ocean waves. This is made possible in that the positive displacement pump comprises pistons having different volume displacements. The height of the incoming waves is measured by a membrane box connected to a transducer which generates signals such that only that piston of the plurality of pistons is made to operate, which has by design a volume displacement which gives the optimal recovery of themore » energy of the ocean waves. The or these pistons pump a working fluid into a storage vessel, which allows the generation of peak load as well as base load electrical energy.« less

A comparison of neutron and gamma damage effects on silica glass in a nuclear reactor radiation environment

NASA Astrophysics Data System (ADS)

Holcomb, David E.; Miller, Don W.

1993-08-01

A study of the relative damage effects of neutrons and gamma rays on silica glass in a nuclear reactor radiation environment is reported. The neutron and gamma energy spectra of the Ohio State University Research Reactor beam port #1 were applied to silica glass to obtain primary knock-on charged particle energy spectra. The resultant charged particle spectra were then applied to the polyatomic forms of the Lindhard et al. integrodifferential equation for damage energy and the Parkin and Coulter integrodifferential equation for net atomic displacement. The results show that near a nuclear reactor core the vast majority of the dose to silica is due to gamma rays (factor of roughly 40) and that neutrons cause much more displacement damage than gamma rays (35 times the oxygen displacement rate and 500 times the silicon displacement rate). However, pure silica core optical fibers irradiated in a nuclear reactor's mixed neutron/gamma environment exhibit little difference in transmission loss on an equal dose basis compared to fibers irradiated in a gamma only environment, indicating that atomic displacement is not a significant damage mechanism.

Integrated control and health monitoring capacitive displacement sensor development task. Orbit transfer rocket engine technology program

NASA Technical Reports Server (NTRS)

Collamore, Frank N.

1989-01-01

The development of a miniature multifunction turbomachinery shaft displacement sensor using state-of-the-art non-contract capacitive sensing technology is described. Axial displacement, radial displacement, and speed are sensed using a single probe within the envelope normally required for a single function. A survey of displacement sensing technology is summarized including inductive, capacitive, optical and ultrasonic techniques. The design and operation of an experimental triple function sensor is described. Test results are included showing calibration tests and simultaneous dynamic testing of multiple functions. Recommendations for design changes are made to improve low temperature performance, reliability, and for design of a flight type signal conditioning unit.

A Demonstration of Optimal Apodization Determination for Proper Lateral Modulation

NASA Astrophysics Data System (ADS)

Sumi, Chikayoshi; Komiya, Yuichi; Uga, Shinya

2009-07-01

We have realized effective ultrasound (US) beamformings by the steering of plural beams and apodizations for B-mode imaging with a high lateral resolution and accurate measurement of tissue or blood displacement vector and/or strain tensor using the multidimensional cross-spectrum phase gradient method (MCSPGM), or multidimensional autocorrelation or Doppler methods (MAM and MDM) using multidimensional analytic signals. For instance, the coherent superposition of the steered beams performed in the lateral cosine modulation method (LCM) has a higher potential for realizing a more accurate measurement of a displacement vector than the synthesis of the displacement vector using the accurately measured axial displacements obtained by the multidimensional synthetic aperture method (MDSAM), multidirectional transmission method (MTM) or the use of plural US transducers. Originally, the apodization function to be used for realizing a designed point spread function (PSF) was obtained by the Fraunhofer approximation (FA). However, to obtain the best approximated, designed PSF in the least-squares sense, we proposed a linear optimization (LO) method. Furthermore, on the basis of the knowledge about the losts of US energy during the propagation, we have recently developed a nonlinear optimization (NLO) method, in which the feet of the main lobes in apodization function are properly truncated. Thus, NLO also allows the decrease in the number of channels or the confinement of the effective aperture. In this study, to gain insight into the ideal shape of the PSF, the accuracies of the two-dimensional (2D) displacement vector measurements were compared for typical PSFs with distinct lateral envelope shapes, particularly, in terms of full width at half maximum (FWHM) and the length of the feet, i.e., the Gaussian function, Hanning window and parabolic function. It was confirmed that a PSF having a wide FWHM and short feet was ideal. Such a PSF yielded an echo with a high signal-to-noise ratio (SNR), a large bandwidth and a large maximum spectrum of the center frequency. Moreover, for the three PSFs used, by calculating the PSFs using a typical transducer model and the apodization functions obtained by the respective LO and NLO methods and FA, we compare the approximation accuracies of the realized PSFs. NLO was effective for realizing such an ideal PSF. In addition, NLO allowed the significant decrease in the number of channels or the confinement of the effective aperture. Thus, in the comparisons of the three distinct PSFs, we obtain an appropriate apodization function. This study will assist the realization of the best lateral modulation.

A nanoscale perspective on the effects of transverse microprestress on drying creep of nanoporous solids

NASA Astrophysics Data System (ADS)

Sinko, Robert; Bažant, Zdeněk P.; Keten, Sinan

2018-01-01

The Pickett effect describes the excess non-additive strain developed during drying of a nanoporous solid material under creep. One explanation for its origins, developed using micromechanical models, is the progressive relaxation of internally developed microprestress. However, these models have not explicitly considered the effects of this microprestress on nanoscale energy barriers that govern the relative motion and displacement between nanopore walls during deformation. Here, we evaluate the nanoscale effects of transverse microprestresses on the drying creep behaviour of a nanoscale slit pore using coarse-grained molecular dynamics. We find that the underlying energy barrier depends exponentially on the transverse microprestress, which is attributed to changes in the effective viscosity and degree of nanoconfinement of molecules in the water interlayer. Specifically, as the transverse microprestress is relaxed (i.e. its magnitude decreases), the activation energy barrier is reduced, thereby leading to an acceleration of the creep behaviour and a stronger Pickett effect. Based on our simulation results, we introduce a new microprestress-dependent energy term into our existing Arrhenius model, which describes the relative displacement of pore walls as a function of the underlying activation energy barriers. Our findings further verify the existing micromechanical theories for the origin of the Pickett effect and establish a quantitative relationship between the transverse microprestress and the intensity of the Pickett effect.

Large Deformation and Adhesive Contact Studies of Axisymmetric Membranes

PubMed Central

Laprade, Evan J.; Long, Rong; Pham, Jonathan; Lawrence, Jimmy; Emrick, Todd; Crosby, Alfred; Hui, Chung-Yuen; Shull, Kenneth R.

2013-01-01

A model membrane contact system consisting of an acrylic copolymer membrane and polydimethyl-siloxane substrate was utilized to evaluate a recently developed nonlinear large-deformation adhesive contact analysis. Direct measurements of the local membrane apex strain during non-contact inflation indicated that the neo-Hookean model provides an accurate measure of membrane strain and supports its use as the strain energy function for the analysis. A time dependent modulus emerges from the analysis, with principal tensions obtained from a comparison of predicted and experimental membrane profiles. A displacement controlled geometry was more easily modeled than the pressure controlled geometry, the applicability of the analysis was limited by wrinkling instabilities. The substantial viscoelastic behavior of these membranes made it difficult to describe the entire membrane with a single modulus, given the nonuniform deformation history of the membranes. Given the difficulty in determining membrane tension from the measured pressure and profile fits using the model, the peel energy was used as a simpler measure of adhesion. Using an analytical balance in the displacement controlled geometry, the membrane tension at the contact line was directly measured. Coupled with contact angle imaging, the peel energy was determined. For the model membranes studied, this peel energy described the membrane/substrate adhesive interactions quite well, giving well-defined peel energies that were independent of the detailed strain state of the membrane. PMID:23289644

Variable-Domain Displacement Transfer Functions for Converting Surface Strains into Deflections for Structural Deformed Shape Predictions

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2015-01-01

Variable-Domain Displacement Transfer Functions were formulated for shape predictions of complex wing structures, for which surface strain-sensing stations must be properly distributed to avoid jointed junctures, and must be increased in the high strain gradient region. Each embedded beam (depth-wise cross section of structure along a surface strain-sensing line) was discretized into small variable domains. Thus, the surface strain distribution can be described with a piecewise linear or a piecewise nonlinear function. Through discretization, the embedded beam curvature equation can be piece-wisely integrated to obtain the Variable-Domain Displacement Transfer Functions (for each embedded beam), which are expressed in terms of geometrical parameters of the embedded beam and the surface strains along the strain-sensing line. By inputting the surface strain data into the Displacement Transfer Functions, slopes and deflections along each embedded beam can be calculated for mapping out overall structural deformed shapes. A long tapered cantilever tubular beam was chosen for shape prediction analysis. The input surface strains were analytically generated from finite-element analysis. The shape prediction accuracies of the Variable- Domain Displacement Transfer Functions were then determined in light of the finite-element generated slopes and deflections, and were fofound to be comparable to the accuracies of the constant-domain Displacement Transfer Functions

Modified Displacement Transfer Functions for Deformed Shape Predictions of Slender Curved Structures with Varying Curvatives

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2014-01-01

To eliminate the need to use finite-element modeling for structure shape predictions, a new method was invented. This method is to use the Displacement Transfer Functions to transform the measured surface strains into deflections for mapping out overall structural deformed shapes. The Displacement Transfer Functions are expressed in terms of rectilinearly distributed surface strains, and contain no material properties. This report is to apply the patented method to the shape predictions of non-symmetrically loaded slender curved structures with different curvatures up to a full circle. Because the measured surface strains are not available, finite-element analysis had to be used to analytically generate the surface strains. Previously formulated straight-beam Displacement Transfer Functions were modified by introducing the curvature-effect correction terms. Through single-point or dual-point collocations with finite-elementgenerated deflection curves, functional forms of the curvature-effect correction terms were empirically established. The resulting modified Displacement Transfer Functions can then provide quite accurate shape predictions. Also, the uniform straight-beam Displacement Transfer Function was applied to the shape predictions of a section-cut of a generic capsule (GC) outer curved sandwich wall. The resulting GC shape predictions are quite accurate in partial regions where the radius of curvature does not change sharply.

Considerable knock-on displacement of metal atoms under a low energy electron beam.

PubMed

Gu, Hengfei; Li, Geping; Liu, Chengze; Yuan, Fusen; Han, Fuzhou; Zhang, Lifeng; Wu, Songquan

2017-03-15

Under electron beam irradiation, knock-on atomic displacement is commonly thought to occur only when the incident electron energy is above the incident-energy threshold of the material in question. However, we report that when exposed to intense electrons at room temperature at a low incident energy of 30 keV, which is far below the theoretically predicted incident-energy threshold of zirconium, Zircaloy-4 (Zr-1.50Sn-0.25Fe-0.15Cr (wt.%)) surfaces can undergo considerable displacement damage. We demonstrate that electron beam irradiation of the bulk Zircaloy-4 surface resulted in a striking radiation effect that nanoscale precipitates within the surface layer gradually emerged and became clearly visible with increasing the irradiation time. Our transmission electron microscope (TEM) observations further reveal that electron beam irradiation of the thin-film Zircaly-4 surface caused the sputtering of surface α-Zr atoms, the nanoscale atomic restructuring in the α-Zr matrix, and the amorphization of precipitates. These results are the first direct evidences suggesting that displacement of metal atoms can be induced by a low incident electron energy below threshold. The presented way to irradiate may be extended to other materials aiming at producing appealing properties for applications in fields of nanotechnology, surface technology, and others.

Radiation degradation prediction for InGaP solar cells by using appropriate estimation method for displacement threshold energy

NASA Astrophysics Data System (ADS)

Okuno, Y.; Okuda, S.; Akiyoshi, M.; Oka, T.; Harumoto, M.; Omura, K.; Kawakita, S.; Imaizumi, M.; Messenger, S. R.; Lee, K. H.; Yamaguchi, M.

2017-09-01

InGaP solar cells are not predicted to be susceptible to displacement damage by irradiation with electrons at energies lower than 100 keV from non-ionizing energy loss (NIEL) calculations. However, it is recently observed that InGaP solar cells are shown to degrade by irradiation with 60 keV electrons. This degradation is considered to be caused by radiation defects but is not clear. In this study, the kind of the defects generated by electrons at energies lower than 100 keV is found by deep-level transient spectroscopy (DLTS). The result of DLTS indicates that the prediction of primary knock-on atoms by using the radiation damage model is different from the experiment. In order to suggest the generation mechanism of radiation defects, we propose a new displacement threshold energy (Ed) by using a new technique in which NIEL and the introduction rate of radiation defects are combined. The degradation prediction by using estimated Ed is found to agree well with the degradation of electric power of InGaP solar cells irradiated by low-energy electrons. From the theory of radiation defects, we propose a new obtaining process of suitable degradation prediction by the displacement damage dose method.

Spectroscopic ellipsometry in vacuum ultraviolet spectral area

NASA Astrophysics Data System (ADS)

Fuchs, Detlef

An ellipsometer is developed and built, which allows the direct spectroscopic evaluation of dielectric function of solid bodies in the energy area 5 to 35 eV. A linear polarized synchrotron radiation was used as light source. The Stokes parameters and the Mueller matrices were used for the mathematical modeling, which take into account the properties of the synchrotron light and the analyzer, which depend on the wavelength. The crystals of the semiconductor bindings GaAs, GaP, InP and ZnS were examined. Ellipsometric measurements and reflection spectra show a displacement of spectral structures towards lower photon energies after the storage.

Heteroaromatic π-Stacking Energy Landscapes

PubMed Central

2014-01-01

In this study we investigate π-stacking interactions of a variety of aromatic heterocycles with benzene using dispersion corrected density functional theory. We calculate extensive potential energy surfaces for parallel-displaced interaction geometries. We find that dispersion contributes significantly to the interaction energy and is complemented by a varying degree of electrostatic interactions. We identify geometric preferences and minimum interaction energies for a set of 13 5- and 6-membered aromatic heterocycles frequently encountered in small drug-like molecules. We demonstrate that the electrostatic properties of these systems are a key determinant for their orientational preferences. The results of this study can be applied in lead optimization for the improvement of stacking interactions, as it provides detailed energy landscapes for a wide range of coplanar heteroaromatic geometries. These energy landscapes can serve as a guide for ring replacement in structure-based drug design. PMID:24773380

Theoretical Evaluation of Electroactive Polymer Based Micropump Diaphragm for Air Flow Control

NASA Technical Reports Server (NTRS)

Xu, Tian-Bing; Su, Ji; Zhang, Qiming

2004-01-01

An electroactive polymer (EAP), high energy electron irradiated poly(vinylidene fluoride-trifluoroethylene) [P(VDFTrFE)] copolymer, based actuation micropump diaphragm (PAMPD) have been developed for air flow control. The displacement strokes and profiles as a function of amplifier and frequency of electric field have been characterized. The volume stroke rates (volume rate) as function of electric field, driving frequency have been theoretically evaluated, too. The PAMPD exhibits high volume rate. It is easily tuned with varying of either amplitude or frequency of the applied electric field. In addition, the performance of the diaphragms were modeled and the agreement between the modeling results and experimental data confirms that the response of the diaphragms follow the design parameters. The results demonstrated that the diaphragm can fit some future aerospace applications to replace the traditional complex mechanical systems, increase the control capability and reduce the weight of the future air dynamic control systems. KEYWORDS: Electroactive polymer (EAP), micropump, diaphragm, actuation, displacement, volume rate, pumping speed, clamping ratio.

Determination of recombination radius in Si for binary collision approximation codes

DOE PAGES

Vizkelethy, Gyorgy; Foiles, Stephen M.

2015-09-11

Displacement damage caused by ions or neutrons in microelectronic devices can have significant effect on the performance of these devices. Therefore, it is important to predict not only the displacement damage profile, but also its magnitude precisely. Analytical methods and binary collision approximation codes working with amorphous targets use the concept of displacement energy, the energy that a lattice atom has to receive to create a permanent replacement. It was found that this “displacement energy” is direction dependent; it can range from 12 to 32 eV in silicon. Obviously, this model fails in BCA codes that work with crystalline targets,more » such as Marlowe. Marlowe does not use displacement energy; instead, it uses lattice binding energy only and then pairs the interstitial atoms with vacancies. Then based on the configuration of the Frenkel pairs it classifies them as close, near, or distant pairs, and considers the distant pairs the permanent replacements. Unfortunately, this separation is an ad hoc assumption, and the results do not agree with molecular dynamics calculations. After irradiation, there is a prompt recombination of interstitials and vacancies if they are nearby, within a recombination radius. In order to implement this recombination radius in Marlowe, we used the comparison of MD and Marlowe calculation in a range of ion energies in single crystal silicon target. As a result, the calculations showed that a single recombination radius of ~7.4 Å in Marlowe for a range of ion energies gives an excellent agreement with MD.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azadi, Sam, E-mail: s.azadi@ucl.ac.uk; Cohen, R. E.

We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimalmore » VMC and DMC binding energies of −2.3(4) and −2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is −2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods.« less

Structure, Stabilities, Thermodynamic Properties, and IR Spectra of Acetylene Clusters (C2H2)n=2-5.

PubMed

Karthikeyan, S; Lee, Han Myoung; Kim, Kwang S

2010-10-12

There are no clear conclusions over the structures of the acetylene clusters. In this regard, we have carried out high-level calculations for acetylene clusters (C2H2)2-5 using dispersion-corrected density functional theory (DFT-D), Møller-Plesset second-order perturbation theory (MP2); and coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)] at the complete basis set limit. The lowest energy structure of the acetylene dimer has a T-shaped structure of C2v symmetry, but it is nearly isoenergetic to the displaced stacked structure of C2h symmetry. We find that the structure shows the quantum statistical distribution for configurations between the T-shaped and displaced stacked structures for which the average angle (|θ̃|) between two acetylene molecules would be 53-78°, close to the T-shaped structure. The trimer has a triangular structure of C3h symmetry. The tetramer has two lowest energy isomers of S4 and C2h symmetry in zero-point energy (ZPE)-uncorrected energy (ΔEe), but one lowest energy isomer of C2v symmetry in ZPE-corrected energy (ΔE0). For the pentamer, the global minimum structure is C1 symmetry with eight sets of T-type π-H interactions and a set of π-π interactions. Our high-level ab initio calculations are consistent with available experimental data.

Modeling the Impact of Deformation on Unstable Miscible Displacements in Porous Media

NASA Astrophysics Data System (ADS)

Santillán, D.; Cueto-Felgueroso, L.

2014-12-01

Coupled flow and geomechanics is a critical research challenge in engineering and the geosciences. The simultaneous flow of two or more fluids with different densities or viscosities through deformable media is ubiquitous in environmental, industrial, and biological processes, including the removal of non-aqueous phase liquids from underground water bodies, the geological storage of CO2, and current challenges in energy technologies, such as enhanced geothermal systems, unconventional hydrocarbon resources or enhanced oil recovery techniques. Using numerical simulation, we study the interplay between viscous-driven flow instabilities (viscous fingering) and rock mechanics, and elucidate the structure of the displacement patterns as a function of viscosity contrast, injection rate and rock mechanical properties. Finally, we discuss the role of medium deformation on transport and mixing processes in porous media.

The sliding-helix voltage sensor

PubMed Central

Peyser, Alexander; Nonner, Wolfgang

2012-01-01

The voltage sensor (VS) domain of voltage-gated ion channels underlies electrical excitability of living cells. We simulate a mesoscale model of the VS domain to determine the functional consequences of some of its physical elements. Our mesoscale model is based on VS charges, linear dielectrics and whole-body motion, applied to an S4 ‘sliding helix’. The electrostatics under voltage-clamped boundary conditions are solved consistently using a boundary element method. Based on electrostatic configurational energy, statistical-mechanical expectations of the experimentally observable relation between displaced charge and membrane voltage are predicted. Consequences of the model are investigated for variations of: S4 configuration (α- and 310-helical), countercharge alignment with S4 charges, protein polarizability, geometry of the gating canal, screening of S4 charges by the baths, and fixed charges located at the bath interfaces. The sliding helix VS domain has an inherent electrostatic stability in the explored parameter space: countercharges present in the region of weak dielectric always retain an equivalent S4 charge in that region but allow sliding movements displacing 3 to 4 e0. That movement is sensitive to small energy variations (< 2kT) along the path dependent on a number of electrostatic parameters tested in our simulations. These simulations show how the slope of the relation between displaced charge and voltage could be tuned in a channel. PMID:22907204

Scale-invariant Green-Kubo relation for time-averaged diffusivity

NASA Astrophysics Data System (ADS)

Meyer, Philipp; Barkai, Eli; Kantz, Holger

2017-12-01

In recent years it was shown both theoretically and experimentally that in certain systems exhibiting anomalous diffusion the time- and ensemble-averaged mean-squared displacement are remarkably different. The ensemble-averaged diffusivity is obtained from a scaling Green-Kubo relation, which connects the scale-invariant nonstationary velocity correlation function with the transport coefficient. Here we obtain the relation between time-averaged diffusivity, usually recorded in single-particle tracking experiments, and the underlying scale-invariant velocity correlation function. The time-averaged mean-squared displacement is given by 〈δ2¯〉 ˜2 DνtβΔν -β , where t is the total measurement time and Δ is the lag time. Here ν is the anomalous diffusion exponent obtained from ensemble-averaged measurements 〈x2〉 ˜tν , while β ≥-1 marks the growth or decline of the kinetic energy 〈v2〉 ˜tβ . Thus, we establish a connection between exponents that can be read off the asymptotic properties of the velocity correlation function and similarly for the transport constant Dν. We demonstrate our results with nonstationary scale-invariant stochastic and deterministic models, thereby highlighting that systems with equivalent behavior in the ensemble average can differ strongly in their time average. If the averaged kinetic energy is finite, β =0 , the time scaling of 〈δ2¯〉 and 〈x2〉 are identical; however, the time-averaged transport coefficient Dν is not identical to the corresponding ensemble-averaged diffusion constant.

Representation of deformable motion for compression of dynamic cardiac image data

NASA Astrophysics Data System (ADS)

Weinlich, Andreas; Amon, Peter; Hutter, Andreas; Kaup, André

2012-02-01

We present a new approach for efficient estimation and storage of tissue deformation in dynamic medical image data like 3-D+t computed tomography reconstructions of human heart acquisitions. Tissue deformation between two points in time can be described by means of a displacement vector field indicating for each voxel of a slice, from which position in the previous slice at a fixed position in the third dimension it has moved to this position. Our deformation model represents the motion in a compact manner using a down-sampled potential function of the displacement vector field. This function is obtained by a Gauss-Newton minimization of the estimation error image, i. e., the difference between the current and the deformed previous slice. For lossless or lossy compression of volume slices, the potential function and the error image can afterwards be coded separately. By assuming deformations instead of translational motion, a subsequent coding algorithm using this method will achieve better compression ratios for medical volume data than with conventional block-based motion compensation known from video coding. Due to the smooth prediction without block artifacts, particularly whole-image transforms like wavelet decomposition as well as intra-slice prediction methods can benefit from this approach. We show that with discrete cosine as well as with Karhunen-Lo`eve transform the method can achieve a better energy compaction of the error image than block-based motion compensation while reaching approximately the same prediction error energy.

Displacement as a predictor of functional impairment in tsunami-exposed children.

PubMed

Lee, Christopher; Du, Ye Beverly; Christina, Desy; Palfrey, Judith; O'Rourke, Edward; Belfer, Myron

2015-01-01

Thirty months after the Indian Ocean tsunami of 26 December 2004, thousands of families in Aceh Province, Indonesia, remained in temporary barracks while sanitation conditions and non-governmental organisation support deteriorated. This study sought to determine the factors associated with functional impairment in a sample of 138 displaced and non-displaced Acehnese children. Using multivariate linear regression models, it was found that displacement distance was a consistent predictor of impairment using the Brief Impairment Scale. Exposure to tsunami-related trauma markers was not significantly linked with impairment in the model. Paternal employment was a consistent protective factor for child functioning. These findings suggest that post-disaster displacement and the subsequent familial economic disruption are significant predictors of impaired functioning in children's daily activities. Post-disaster interventions should consider the disruption of familiar environments for families and children when relocating vulnerable populations to avoid deleterious impacts on children's functioning. © 2014 The Author(s). Disasters © Overseas Development Institute, 2014.

Curved Displacement Transfer Functions for Geometric Nonlinear Large Deformation Structure Shape Predictions

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran; Lung, Shun-Fat

2017-01-01

For shape predictions of structures under large geometrically nonlinear deformations, Curved Displacement Transfer Functions were formulated based on a curved displacement, traced by a material point from the undeformed position to deformed position. The embedded beam (depth-wise cross section of a structure along a surface strain-sensing line) was discretized into multiple small domains, with domain junctures matching the strain-sensing stations. Thus, the surface strain distribution could be described with a piecewise linear or a piecewise nonlinear function. The discretization approach enabled piecewise integrations of the embedded-beam curvature equations to yield the Curved Displacement Transfer Functions, expressed in terms of embedded beam geometrical parameters and surface strains. By entering the surface strain data into the Displacement Transfer Functions, deflections along each embedded beam can be calculated at multiple points for mapping the overall structural deformed shapes. Finite-element linear and nonlinear analyses of a tapered cantilever tubular beam were performed to generate linear and nonlinear surface strains and the associated deflections to be used for validation. The shape prediction accuracies were then determined by comparing the theoretical deflections with the finiteelement- generated deflections. The results show that the newly developed Curved Displacement Transfer Functions are very accurate for shape predictions of structures under large geometrically nonlinear deformations.

Existence and energy decay of a nonuniform Timoshenko system with second sound

NASA Astrophysics Data System (ADS)

Hamadouche, Taklit; Messaoudi, Salim A.

2018-02-01

In this paper, we consider a linear thermoelastic Timoshenko system with variable physical parameters, where the heat conduction is given by Cattaneo's law and the coupling is via the displacement equation. We discuss the well-posedness and the regularity of solution using the semigroup theory. Moreover, we establish the exponential decay result provided that the stability function χ r(x)=0. Otherwise, we show that the solution decays polynomially.

Semiconductor spintronics: The full matrix approach

NASA Astrophysics Data System (ADS)

Rossani, A.

2015-12-01

A new model, based on an asymptotic procedure for solving the spinor kinetic equations of electrons and phonons is proposed, which gives naturally the displaced Fermi-Dirac distribution function at the leading order. The balance equations for the electron number, energy density and momentum, plus the Poisson’s equation, constitute now a system of six equations. Moreover, two equations for the evolution of the spin densities are added, which account for a general dispersion relation.

Surface displacements and energy release rates for constant stress drop slip zones in joined elastic quarter spaces

NASA Astrophysics Data System (ADS)

Rodgers, Michael J.; Wen, Shengmin; Keer, Leon M.

2000-08-01

A three-dimensional quasi-static model of faulting in an elastic half-space with a horizontal change of material properties (i.e., joined elastic quarter spaces) is considered. A boundary element method is used with a stress drop slip zone approach so that the fault surface relative displacements as well as the free surface displacements are approximated in elements over their respective domains. Stress intensity factors and free surface displacements are calculated for a variety of cases to show the phenomenological behavior of faulting in such a medium. These calculations showed that the behavior could be distinguished from a uniform half-space. Slip in a stiffer material increases, while slip in a softer material decreases the energy release rate and the free surface displacements. Also, the 1989 Kalapana earthquake was located on the basis of a series of forward searches using this method and leveling data. The located depth is 8 km, which is the closer to the seismically inferred depth than that determined from other models. Finally, the energy release rate, which can be used as a fracture criterion for fracture at this depth, is calculated to be 11.1×106 J m-2.

Computational and Experimental Studies of the Radiation Response of Gd2Ti2O7 Pyrochlore

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devanathan, Ram; Weber, William J.

2005-12-16

The structure and property changes in Gd2Ti2O7 (polycrystalline pyrochlore) were examined following irradiation with 1 MeV Kr+, 0.6 MeV Bi+ and 4 MeV Au2+ ions over the temperature range 30-950 K. Gd2Ti2O7 readily amorphizes with a low temperature (30 K) critical dose for amorphization of {approx} 0.15 displacements per atom (dpa). The critical temperature above which amorphization does not occur is about 1190 K. Nano-indentation studies reveal that the structural changes were accompanied by decreases of 15% in the Young's modulus. 1 MeV Kr+ irradiation of amorphous Gd2Ti2O7 at 1065 K resulted in ion-beam-assisted recrystallization. These experimental studies were complementedmore » with molecular dynamics simulations of low energy recoils in Gd2Ti2O7 and Gd2Zr2O7 using a Buckingham type potential. The displacement threshold energy surface in both pyrochlores is highly anisotropic. Displacement energies are higher for all sublattices in the titanate pyrochlore compared to the zirconate. Ti sublattice displacements require energies in excess of 100 eV, and result in multiple displacements and defect clusters. The formation of these clusters might impede dynamic defect recovery and facilitate amorphization.« less

Effects of wind-energy facilities on grassland bird distributions

USGS Publications Warehouse

Shaffer, Jill A.; Buhl, Deb

2016-01-01

The contribution of renewable energy to meet worldwide demand continues to grow. Wind energy is one of the fastest growing renewable sectors, but new wind facilities are often placed in prime wildlife habitat. Long-term studies that incorporate a rigorous statistical design to evaluate the effects of wind facilities on wildlife are rare. We conducted a before-after-control-impact (BACI) assessment to determine if wind facilities placed in native mixed-grass prairies displaced breeding grassland birds. During 2003–2012, we monitored changes in bird density in 3 study areas in North Dakota and South Dakota (U.S.A.). We examined whether displacement or attraction occurred 1 year after construction (immediate effect) and the average displacement or attraction 2–5 years after construction (delayed effect). We tested for these effects overall and within distance bands of 100, 200, 300, and >300 m from turbines. We observed displacement for 7 of 9 species. One species was unaffected by wind facilities and one species exhibited attraction. Displacement and attraction generally occurred within 100 m and often extended up to 300 m. In a few instances, displacement extended beyond 300 m. Displacement and attraction occurred 1 year after construction and persisted at least 5 years. Our research provides a framework for applying a BACI design to displacement studies and highlights the erroneous conclusions that can be made without the benefit of adopting such a design. More broadly, species-specific behaviors can be used to inform management decisions about turbine placement and the potential impact to individual species. Additionally, the avoidance distance metrics we estimated can facilitate future development of models evaluating impacts of wind facilities under differing land-use scenarios.

Effects of wind-energy facilities on breeding grassland bird distributions.

PubMed

Shaffer, Jill A; Buhl, Deborah A

2016-02-01

The contribution of renewable energy to meet worldwide demand continues to grow. Wind energy is one of the fastest growing renewable sectors, but new wind facilities are often placed in prime wildlife habitat. Long-term studies that incorporate a rigorous statistical design to evaluate the effects of wind facilities on wildlife are rare. We conducted a before-after-control-impact (BACI) assessment to determine if wind facilities placed in native mixed-grass prairies displaced breeding grassland birds. During 2003-2012, we monitored changes in bird density in 3 study areas in North Dakota and South Dakota (U.S.A.). We examined whether displacement or attraction occurred 1 year after construction (immediate effect) and the average displacement or attraction 2-5 years after construction (delayed effect). We tested for these effects overall and within distance bands of 100, 200, 300, and >300 m from turbines. We observed displacement for 7 of 9 species. One species was unaffected by wind facilities and one species exhibited attraction. Displacement and attraction generally occurred within 100 m and often extended up to 300 m. In a few instances, displacement extended beyond 300 m. Displacement and attraction occurred 1 year after construction and persisted at least 5 years. Our research provides a framework for applying a BACI design to displacement studies and highlights the erroneous conclusions that can be made without the benefit of adopting such a design. More broadly, species-specific behaviors can be used to inform management decisions about turbine placement and the potential impact to individual species. Additionally, the avoidance distance metrics we estimated can facilitate future development of models evaluating impacts of wind facilities under differing land-use scenarios. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Particle transport in low-energy ventilation systems. Part 1: theory of steady states.

PubMed

Bolster, D T; Linden, P F

2009-04-01

Many modern low-energy ventilation schemes, such as displacement or natural ventilation, take advantage of temperature stratification in a space, extracting the warmest air from the top of the room. The adoption of these energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. In this work we study the steady state transport of particulate contaminants in a displacement-ventilated space. Representing heat sources as ideal sources of buoyancy, analytical models are developed that allow us to compare the average efficiency of contaminant removal between traditional and modern low-energy systems. We found that on average traditional and low-energy systems are similar in overall pollutant removal efficiency, although quite different vertical distributions of contaminant can exist, thus affecting individual exposure. While the main focus of this work is on particles where the dominant mode of deposition is by gravitational settling, we also discuss additional deposition mechanisms and show that the qualitative observations we make carry over to cases where such mechanisms must be included. We illustrate that while average concentration of particles for traditional mixing systems and low energy displacement systems are similar, local concentrations can vary significantly with displacement systems. Depending on the source of the particles this can be better or worse in terms of occupant exposure and engineers should take due diligence accordingly when designing ventilation systems.

Static non-reciprocity in mechanical metamaterials.

PubMed

Coulais, Corentin; Sounas, Dimitrios; Alù, Andrea

2017-02-23

Reciprocity is a general, fundamental principle governing various physical systems, which ensures that the transfer function-the transmission of a physical quantity, say light intensity-between any two points in space is identical, regardless of geometrical or material asymmetries. Breaking this transmission symmetry offers enhanced control over signal transport, isolation and source protection. So far, devices that break reciprocity (and therefore show non-reciprocity) have been mostly considered in dynamic systems involving electromagnetic, acoustic and mechanical wave propagation associated with fields varying in space and time. Here we show that it is possible to break reciprocity in static systems, realizing mechanical metamaterials that exhibit vastly different output displacements under excitation from different sides, as well as one-way displacement amplification. This is achieved by combining large nonlinearities with suitable geometrical asymmetries and/or topological features. In addition to extending non-reciprocity and isolation to statics, our work sheds light on energy propagation in nonlinear materials with asymmetric crystalline structures and topological properties. We anticipate that breaking reciprocity will open avenues for energy absorption, conversion and harvesting, soft robotics, prosthetics and optomechanics.

Constraining the p¯/p ratio in TeV cosmic rays with observations of the Moon shadow by HAWC

NASA Astrophysics Data System (ADS)

Abeysekara, A. U.; Albert, A.; Alfaro, R.; Alvarez, C.; Álvarez, J. D.; Arceo, R.; Arteaga-Velázquez, J. C.; Avila Rojas, D.; Ayala Solares, H. A.; Belmont-Moreno, E.; BenZvi, S. Y.; Braun, J.; Brisbois, C.; Caballero-Mora, K. S.; Capistrán, T.; Carramiñana, A.; Casanova, S.; Castillo, M.; Cotti, U.; Cotzomi, J.; Coutiño de León, S.; De León, C.; De la Fuente, E.; Diaz Hernandez, R.; Dichiara, S.; Dingus, B. L.; DuVernois, M. A.; Ellsworth, R. W.; Engel, K.; Enríquez-Rivera, O.; Fleischhack, H.; Fraija, N.; Galván-Gámez, A.; García-González, J. A.; González Muñoz, A.; González, M. M.; Hampel-Arias, Z.; Harding, J. P.; Hernandez, S.; Hona, B.; Hueyotl-Zahuantitla, F.; Hui, C. M.; Hüntemeyer, P.; Iriarte, A.; Jardin-Blicq, A.; Joshi, V.; Kaufmann, S.; Lara, A.; Lee, W. H.; León Vargas, H.; Linnemann, J. T.; Longinotti, A. L.; Luis-Raya, G.; Luna-García, R.; López-Coto, R.; Malone, K.; Marinelli, S. S.; Martinez, O.; Martinez-Castellanos, I.; Martínez-Castro, J.; Martínez-Huerta, H.; Matthews, J. A.; Miranda-Romagnoli, P.; Moreno, E.; Mostafá, M.; Nellen, L.; Newbold, M.; Nisa, M. U.; Noriega-Papaqui, R.; Pelayo, R.; Pretz, J.; Pérez-Pérez, E. G.; Ren, Z.; Rho, C. D.; Rivière, C.; Rosa-González, D.; Rosenberg, M.; Ruiz-Velasco, E.; Salesa Greus, F.; Sandoval, A.; Schneider, M.; Schoorlemmer, H.; Seglar Arroyo, M.; Sinnis, G.; Smith, A. J.; Springer, R. W.; Surajbali, P.; Taboada, I.; Tibolla, O.; Torres, I.; Villaseñor, L.; Weisgarber, T.; Westerhoff, S.; Wood, J.; Yapici, T.; Yodh, G. B.; Zepeda, A.; Zhou, H.; HAWC Collaboration

2018-05-01

An indirect measurement of the antiproton flux in cosmic rays is possible as the particles undergo deflection by the geomagnetic field. This effect can be measured by studying the deficit in the flux, or shadow, created by the Moon as it absorbs cosmic rays that are headed toward the Earth. The shadow is displaced from the actual position of the Moon due to geomagnetic deflection, which is a function of the energy and charge of the cosmic rays. The displacement provides a natural tool for momentum/charge discrimination that can be used to study the composition of cosmic rays. Using 33 months of data comprising more than 80 billion cosmic rays measured by the High Altitude Water Cherenkov observatory, we have analyzed the Moon shadow to search for TeV antiprotons in cosmic rays. We present our first upper limits on the p ¯/p fraction, which in the absence of any direct measurements provide the tightest available constraints of ˜1 % on the antiproton fraction for energies between 1 and 10 TeV.

General displaced SU(1, 1) number states: Revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dehghani, A., E-mail: alireza.dehghani@gmail.com, E-mail: a-dehghani@tabrizu.ac.ir

2014-04-15

The most general displaced number states, based on the bosonic and an irreducible representation of the Lie algebra symmetry of su(1, 1) and associated with the Calogero-Sutherland model are introduced. Here, we utilize the Barut-Girardello displacement operator instead of the Klauder-Perelomov counterpart, to construct new kind of the displaced number states which can be classified in nonlinear coherent states regime, too, with special nonlinearity functions. They depend on two parameters, and can be converted into the well-known Barut-Girardello coherent and number states, respectively, depending on which of the parameters equal to zero. A discussion of the statistical properties of thesemore » states is included. Significant are their squeezing properties and anti-bunching effects which can be raised by increasing the energy quantum number. Depending on the particular choice of the parameters of the above scenario, we are able to determine the status of compliance with flexible statistics. Major parts of the issue is spent on something that these states, in fact, should be considered as new kind of photon-added coherent states, too. Which can be reproduced through an iterated action of a creation operator on new nonlinear Barut-Girardello coherent states. Where the latter carry, also, outstanding statistical features.« less

Oxygen-Vacancy-Induced Polar Behavior in (LaFeO 3) 2/(SrFeO 3) Superlattices

DOE PAGES

Mishra, Rohan; Kim, Young-Min; Salafranca, Juan; ...

2014-04-15

Complex oxides displaying ferroelectric and/or multiferroic behavior are of high fundamental and applied interest. In this work, for the first time, we show that it is possible to achieve polar order in a superlattice made up of two nonpolar oxides by means of oxygen vacancy ordering. Using scanning transmission electron microscopy imaging, we show the polar displacement of magnetic Fe ions in a superlattice of (LaFeO 3) 2/(SrFeO 3) grown on a SrTiO 3 substrate. Using density functional theory calculations, we systematically study the effect of epitaxial strain, octahedral rotations, and surface terminations in the superlattice and find them tomore » have a negligible effect on the antipolar displacements of the Fe ions lying in between SrO and LaO layers of the superlattice (i.e., within La 0.5Sr 0.5FeO 3 unit cells). The introduction of oxygen vacancies, on the other hand, triggers a polar displacement of the Fe ions. We confirm this important result using electron energy loss spectroscopy, which shows partial oxygen vacancy ordering in the region where polar displacements are observed and an absence of vacancy ordering outside of that area.« less

Numerical Simulation and Experimental Verification of Hollow and Foam-Filled Flax-Fabric-Reinforced Epoxy Tubular Energy Absorbers Subjected to Crashing

NASA Astrophysics Data System (ADS)

Sliseris, J.; Yan, L.; Kasal, B.

2017-09-01

Numerical methods for simulating hollow and foam-filled flax-fabric-reinforced epoxy tubular energy absorbers subjected to lateral crashing are presented. The crashing characteristics, such as the progressive failure, load-displacement response, absorbed energy, peak load, and failure modes, of the tubes were simulated and calculated numerically. A 3D nonlinear finite-element model that allows for the plasticity of materials using an isotropic hardening model with strain rate dependence and failure is proposed. An explicit finite-element solver is used to address the lateral crashing of the tubes considering large displacements and strains, plasticity, and damage. The experimental nonlinear crashing load vs. displacement data are successfully described by using the finite-element model proposed. The simulated peak loads and absorbed energy of the tubes are also in good agreement with experimental results.

Preconditions for constructing a biomechanical model of the heart as an integral musculovascular organ

NASA Astrophysics Data System (ADS)

Edemskii, M. L.; Kogan, V. A.

1981-07-01

Relative to its major function, pumping, the heart should be considered as an integral musculovascular organ. It is precisely this integration in the structural and functional sense which permits the heart not only to perform its pump function as a converter of chemical energy supplied by the blood into mechanical flow energy but also to combine the supply and conversion of energy into a single cycle, produce the hydrodynamics of cardiac output in definite fashion, and introduce a correction into the filling phase according to current arterial pressure as the most dynamic index of systemic hemodynamics. The breakdown of the structure of the cardiac pump into elements differing in their functional significance permits us to delineate at least three channels for the utilization of energy supplied to the heart and consumed in the major pumping function: the mechanical work performed by the lower part of the cardiac muscle that is displaced into the ventricular space, the energy consumed on maintaining the systolic pressure of the myocardial fibers which form the relatively immobile upper and side walls of the heart, and the energy consumed on maintaining the high tone of the muscular walls of the coronary arteries and arterioles which form the hydraulic frame of the heart. A representation of the heart which includes muscular and vascular components, in our view, is the basic prerequisite for the development of mathematical models for the cardiac pump based on energy balance equations and suitable for solving the problems posed by clinical medicine in regard to auxiliary blood circulation.

Mixed finite-element formulations in piezoelectricity and flexoelectricity

PubMed Central

2016-01-01

Flexoelectricity, the linear coupling of strain gradient and electric polarization, is inherently a size-dependent phenomenon. The energy storage function for a flexoelectric material depends not only on polarization and strain, but also strain-gradient. Thus, conventional finite-element methods formulated solely on displacement are inadequate to treat flexoelectric solids since gradients raise the order of the governing differential equations. Here, we introduce a computational framework based on a mixed formulation developed previously by one of the present authors and a colleague. This formulation uses displacement and displacement-gradient as separate variables which are constrained in a ‘weighted integral sense’ to enforce their known relation. We derive a variational formulation for boundary-value problems for piezo- and/or flexoelectric solids. We validate this computational framework against available exact solutions. Our new computational method is applied to more complex problems, including a plate with an elliptical hole, stationary cracks, as well as tension and shear of solids with a repeating unit cell. Our results address several issues of theoretical interest, generate predictions of experimental merit and reveal interesting flexoelectric phenomena with potential for application. PMID:27436967

Mixed finite-element formulations in piezoelectricity and flexoelectricity.

PubMed

Mao, Sheng; Purohit, Prashant K; Aravas, Nikolaos

2016-06-01

Flexoelectricity, the linear coupling of strain gradient and electric polarization, is inherently a size-dependent phenomenon. The energy storage function for a flexoelectric material depends not only on polarization and strain, but also strain-gradient. Thus, conventional finite-element methods formulated solely on displacement are inadequate to treat flexoelectric solids since gradients raise the order of the governing differential equations. Here, we introduce a computational framework based on a mixed formulation developed previously by one of the present authors and a colleague. This formulation uses displacement and displacement-gradient as separate variables which are constrained in a 'weighted integral sense' to enforce their known relation. We derive a variational formulation for boundary-value problems for piezo- and/or flexoelectric solids. We validate this computational framework against available exact solutions. Our new computational method is applied to more complex problems, including a plate with an elliptical hole, stationary cracks, as well as tension and shear of solids with a repeating unit cell. Our results address several issues of theoretical interest, generate predictions of experimental merit and reveal interesting flexoelectric phenomena with potential for application.

Photochemical Acceleration of DNA Strand Displacement by Using Ultrafast DNA Photo-crosslinking.

PubMed

Nakamura, Shigetaka; Hashimoto, Hirokazu; Kobayashi, Satoshi; Fujimoto, Kenzo

2017-10-18

DNA strand displacement is an essential reaction in genetic recombination, biological processes, and DNA nanotechnology. In particular, various DNA nanodevices enable complicated calculations. However, it takes time before the output is obtained, so acceleration of DNA strand displacement is required for a rapid-response DNA nanodevice. Herein, DNA strand displacement by using DNA photo-crosslinking to accelerate this displacement is evaluated. The DNA photo-crosslinking of 3-cyanovinylcarbazole ( CNV K) was accelerated at least 20 times, showing a faster DNA strand displacement. The rate of photo-crosslinking is a key factor and the rate of DNA strand displacement is accelerated through ultrafast photo-crosslinking. The rate of DNA strand displacement was regulated by photoirradiation energy. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of crystal-field excitations and infrared active phonons in TbMnO3

NASA Astrophysics Data System (ADS)

Mansouri, S.; Jandl, S.; Balli, M.; Fournier, P.; Mukhin, A. A.; Ivanov, V. Yu; Balbashov, A.; Orlita, M.

2018-05-01

The Tb3+ (4f 8) crystal-field (CF) excitations and the infrared phonons in TbMnO3 are studied as a function of temperature and under an applied magnetic field. The phonon energy shifts reflect local displacement of the oxygen ions that contribute to the CF energy level shifts below 120 K and under magnetic field. The CF polarized transmission spectra provide interesting information about the debated nature of the excitations at 41, 65, 130 cm‑1. We also evaluate the contribution of the charge transfer mechanism to the magnetoelectric process in TbMnO3 under magnetic field.

First principles investigation of structural, vibrational and thermal properties of black and blue phosphorene

NASA Astrophysics Data System (ADS)

Arif Khalil, R. M.; Ahmad, Javed; Rana, Anwar Manzoor; Bukhari, Syed Hamad; Tufiq Jamil, M.; Tehreem, Tuba; Nissar, Umair

2018-05-01

In this investigation, structural, dynamical and thermal properties of black and blue phosphorene (P) are presented through the first principles calculations based on the density functional theory (DFT). These DFT calculations depict that due to the approximately same values of ground state energy at zero Kelvin and Helmholtz free energy at room-temperature, it is expected that both structures can coexist at transition temperature. Lattice dynamics of both phases were investigated by using the finite displacement supercell approach. It is noticed on the basis of harmonic approximation thermodynamic calculations that the blue phase is thermodynamically more stable than the black phase above 155 K.

Mitigating environmental impacts through the energetic use of wood: Regional displacement factors generated by means of substituting non-wood heating systems.

PubMed

Wolf, Christian; Klein, Daniel; Richter, Klaus; Weber-Blaschke, Gabriele

2016-11-01

Wood biomass, especially when applied for heating, plays an important role for mitigating environmental impacts such as climate change and the transition towards higher shares of renewable energy in today's energy mix. However, the magnitude of mitigation benefits and burdens associated with wood use can vary greatly depending on regional parameters such as the displaced fossil reference or heating mix. Therefore, regionalized displacement factors, considering region-specific production conditions and substituted products are required when assessing the precise contribution of wood biomass towards the mitigation of environmental impacts. We carried out Life Cycle Assessments of wood heating systems for typical Bavarian conditions and substitute energy carriers with a focus on climate change and particulate matter emissions. In order to showcase regional effects, we created weighted displacement factors for the region of Bavaria, based on installed capacities of individual wood heating systems and the harvested tree species distribution. The study reveals that GHG displacements between -57gCO2-eq.∗MJ(-1) of useful energy through the substitution of natural gas with a 15kW spruce pellets heating system and -165gCO2-eq.∗MJ(-1) through the substitution of power utilized for heating with a modern 6kW beech split log heating system can be achieved. It was shown that the GHG mitigation potentials of wood utilization are overestimated through the common use of light fuel oil as the only reference system. We further propose a methodology for the calculation of displacement factors which is adaptable to other regions worldwide. Based on our approach it is possible to generate displacement factors for wood heating systems which enable accurate decision-making for project planning in households, heating plants, communities and also for entire regions. Copyright © 2016 Elsevier B.V. All rights reserved.

Critical evaluation of dipolar, acid-base and charge interactions I. Electron displacement within and between molecules, liquids and semiconductors.

PubMed

Rosenholm, Jarl B

2017-09-01

Specific dipolar, acid-base and charge interactions involve electron displacements. For atoms, single bonds and molecules electron displacement is characterized by electronic potential, absolute hardness, electronegativity and electron gap. In addition, dissociation, bonding, atomization, formation, ionization, affinity and lattice enthalpies are required to quantify the electron displacement in solids. Semiconductors are characterized by valence and conduction band energies, electron gaps and average Fermi energies which in turn determine Galvani potentials of the bulk, space charge layer and surface states. Electron displacement due to interaction between (probe) molecules, liquids and solids are characterized by parameters such as Hamaker constant, solubility parameter, exchange energy density, surface tension, work of adhesion and immersion. They are determined from permittivity, refractive index, enthalpy of vaporization, molar volume, surface pressure and contact angle. Moreover, acidic and basic probes may form adducts which are adsorbed on target substrates in order to establish an indirect measure of polarity, acidity, basicity or hydrogen bonding. Acidic acceptor numbers (AN), basic donor numbers (DN), acidic and basic "electrostatic" (E) and "covalent" (C) parameters determined by enthalpy of adduct formation are considered as general acid-base scales. However, the formal grounds for assignments as dispersive, Lifshitz-van der Waals, polar, acid, base and hydrogen bond interactions are inconsistent. Although correlations are found no of the parameters are mutually fully compatible and moreover the enthalpies of acid-base interaction do not correspond to free energies. In this review the foundations of different acid-base parameters relating to electron displacement within and between (probe) molecules, liquids and (semiconducting) solids are thoroughly investigated and their mutual relationships are evaluated. Copyright © 2017 Elsevier B.V. All rights reserved.

Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wampler, William R.; Myers, Samuel M.

2014-02-01

A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defectsmore » within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.« less

Vibration characteristics of functionally graded carbon nanotube reinforced composite rectangular plates on Pasternak foundation with arbitrary boundary conditions and internal line supports

NASA Astrophysics Data System (ADS)

Zhong, Rui; Wang, Qingshan; Tang, Jinyuan; Shuai, Cijun; Liang, Qian

2018-02-01

This paper presents the first known vibration characteristics of moderately thick functionally graded carbon nanotube reinforced composite rectangular plates on Pasternak foundation with arbitrary boundary conditions and internal line supports on the basis of the firstorder shear deformation theory. Different distributions of single walled carbon nanotubes (SWCNTs) along the thickness are considered. Uniform and other three kinds of functionally graded distributions of carbon nanotubes along the thickness direction of plates are studied. The solutions carried out using an enhanced Ritz method mainly include the following three points: Firstly, create the Lagrange energy function by the energy principle; Secondly, as the main innovation point, the modified Fourier series are chosen as the basic functions of the admissible functions of the plates to eliminate all the relevant discontinuities of the displacements and their derivatives at the edges; Lastly, solve the natural frequencies as well as the associated mode shapes by means of the Ritz-variational energy method. In this study, the influences of the volume fraction of CNTs, distribution type of CNTs, boundary restrain parameters, location of the internal line supports, foundation coefficients on the natural frequencies and mode shapes of the FG-CNT reinforced composite rectangular plates are presented.

The effects of real and artificial Leg Length Discrepancy on mechanical work and energy cost during the gait.

PubMed

Assogba, T F; Boulet, S; Detrembleur, C; Mahaudens, P

2018-01-01

The impacts of Leg Length Discrepancy (LLD) on the kinematic and dynamic parameters of walking have been widely discussed. But little is known on total mechanical work and energy cost. These two variables are more representative of the functional impairment undergone by the LLD patients. To assess the changes of the mechanical work and energy cost of walking in subjects with real LLD and to compare their results with healthy subjects in whom the LLD has been simulated. The mechanical work and energy cost data of 60 healthy subjects (speed: 4km/h) with artificial LLD induced by soles (2 and 4cm), 20 patients (speed: 3.75±0.5km/h) with real LLD and 20 matched subjects (speed: 3.75±0.5km/h) were collected. Statistical comparisons between the groups were performed using a t-paired test and ANOVA. Patients with a real LLD showed a significant decrease in mechanical work and energy cost when compared to norms. Patients with real LLD provide a better recovery when compared to subjects with artificial LLD of 2cm, and a decrease of energy cost and higher muscular efficiency (mechanical work/energy cost) when compared to subjects with artificial LLD of 4cm. Our results showed that patients with a real LLD develop compensatory strategies during gait, probably to minimize the displacement of the body center of mass and consequently reduce the amount of energy expenditure useful for their displacement. Moreover, they adopt a better gait strategy compared to the subjects in whom LLD was simulated. Copyright © 2017 Elsevier B.V. All rights reserved.

Diffusion of phonons through (along and across) the ultrathin crystalline films

NASA Astrophysics Data System (ADS)

Šetrajčić, J. P.; Jaćimovski, S. K.; Vučenović, S. M.

2017-11-01

Instead of usual approach, applying displacement-displacement Green's functions, the momentum-momentum Green's functions will be used to calculate the diffusion tensor. With this type of Green's function we have calculated and analyzed dispersion law in film-structures. A small number of phonon energy levels along the direction of boundary surfaces joint of the film are discrete-ones and in this case standing waves could occur. This is consequence of quantum size effects. These Green's functions enter into Kubo's formula defining diffusion properties of the system and possible heat transfer direction through observed structures. Calculation of the diffusion tensor for phonons in film-structure requires solving of the system of difference equations. Boundary conditions are included into mentioned system through the Hamiltonian of the film-structure. It has been shown that the diagonal elements of the diffusion tensor express discrete behavior of the dispersion law of elementary excitations. More important result is-that they are temperature independent and that their values are much higher comparing with bulk structures. This result favors better heat conduction of the film, but in direction which is perpendicular to boundary film surface. In the same time this significantly favors appearance 2D superconducting surfaces inside the ultra-thin crystal structure, which are parallel to the boundary surface.

The eigenfrequency spectrum of linear magnetohydrodynamic perturbations in stationary equilibria: A variational principle

NASA Astrophysics Data System (ADS)

Andries, Jesse

2010-11-01

The frequencies of the normal modes of oscillation of linear magnetohydrodynamic perturbations of a stationary equilibrium are related to the stationary points of a quadratic functional over the Hilbert space of Lagrangian displacement vectors, which is subject to a constraint. In the absence of a background flow (or of a uniform flow), the relation reduces to the well-known Rayleigh-Ritz variational principle. In contrast to the existing variational principles for perturbations of stationary equilibria, the present treatment does neither impose additional symmetry restrictions on the equilibrium, nor does it involve the generalization to bilinear functionals instead of quadratic forms. This allows a more natural interpretation of the quadratic forms as energy functionals.

Computer-assisted time-averaged holograms of the motion of the surface of the mammalian tympanic membrane with sound stimuli of 0.4 to 25 kHz

PubMed Central

Rosowski, John J.; Cheng, Jeffrey Tao; Ravicz, Michael E.; Hulli, Nesim; Hernandez-Montes, Maria; Harrington, Ellery; Furlong, Cosme

2009-01-01

Time-averaged holograms describing the sound-induced motion of the tympanic membrane (TM) in cadaveric preparations from three mammalian species and one live ear were measured using opto-electronic holography. This technique allows rapid measurements of the magnitude of motion of the tympanic membrane surface at frequencies as high as 25 kHz. The holograms measured in response to low and middle-frequency sound stimuli are similar to previously reported time-averaged holograms. However, at higher frequencies (f > 4 kHz), our holograms reveal unique TM surface displacement patterns that consist of highly-ordered arrangements of multiple local displacement magnitude maxima, each of which is surrounded by nodal areas of low displacement magnitude. These patterns are similar to modal patterns (two-dimensional standing waves) produced by either the interaction of surface waves traveling in multiple directions or the uniform stimulation of modes of motion that are determined by the structural properties and boundary conditions of the TM. From the ratio of the displacement magnitude peaks to nodal valleys in these apparent surface waves, we estimate a Standing Wave Ratio of at least 4 that is consistent with energy reflection coefficients at the TM boundaries of at least 0.35. It is also consistent with small losses within the uniformly stimulated modal surface waves. We also estimate possible TM surface wave speeds that vary with frequency and species from 20 to 65 m/s, consistent with other estimates in the literature. The presence of standing wave or modal phenomena has previously been intuited from measurements of TM function, but is ignored in some models of tympanic membrane function. Whether these standing waves result either from the interactions of multiple surface waves that travel along the membrane, or by uniformly excited modal displacement patterns of the entire TM surface is still to be determined. PMID:19328841

Computer-assisted time-averaged holograms of the motion of the surface of the mammalian tympanic membrane with sound stimuli of 0.4-25 kHz.

PubMed

Rosowski, John J; Cheng, Jeffrey Tao; Ravicz, Michael E; Hulli, Nesim; Hernandez-Montes, Maria; Harrington, Ellery; Furlong, Cosme

2009-07-01

Time-averaged holograms describing the sound-induced motion of the tympanic membrane (TM) in cadaveric preparations from three mammalian species and one live ear were measured using opto-electronic holography. This technique allows rapid measurements of the magnitude of motion of the tympanic membrane surface at frequencies as high as 25 kHz. The holograms measured in response to low and middle-frequency sound stimuli are similar to previously reported time-averaged holograms. However, at higher frequencies (f>4 kHz), our holograms reveal unique TM surface displacement patterns that consist of highly-ordered arrangements of multiple local displacement magnitude maxima, each of which is surrounded by nodal areas of low displacement magnitude. These patterns are similar to modal patterns (two-dimensional standing waves) produced by either the interaction of surface waves traveling in multiple directions or the uniform stimulation of modes of motion that are determined by the structural properties and boundary conditions of the TM. From the ratio of the displacement magnitude peaks to nodal valleys in these apparent surface waves, we estimate a Standing Wave Ratio of at least 4 that is consistent with energy reflection coefficients at the TM boundaries of at least 0.35. It is also consistent with small losses within the uniformly stimulated modal surface waves. We also estimate possible TM surface wave speeds that vary with frequency and species from 20 to 65 m/s, consistent with other estimates in the literature. The presence of standing wave or modal phenomena has previously been intuited from measurements of TM function, but is ignored in some models of tympanic membrane function. Whether these standing waves result either from the interactions of multiple surface waves that travel along the membrane, or by uniformly excited modal displacement patterns of the entire TM surface is still to be determined.

Air displacement plethysmography, dual-energy x-ray absorptiometry, and total body water to evaluate body composition in preschool-age children

USDA-ARS?s Scientific Manuscript database

Anthropometrics and body mass index are only proxies in the evaluation of adiposity in the pediatric population. Air displacement plethysmography technology was not available for children aged 6 months to 9 years until recently. Our study was designed to test the precision of air displacement plethy...

The Impact of Sustainable Development Technology on a Small Economy-The Case of Energy-Saving Technology.

PubMed

Chen, Xiding; Huang, Qinghua; Huang, Weilun; Li, Xue

2018-02-08

We investigated the impact of a sustainable development technology on the macroeconomic variables in a small economy utilizing a case study with a stochastically improving energy saving technology and a stochastically increasing energy price. The results show the technological displacement effects of energy saving technology are stronger, but there are more ambiguous instantaneous returns to physical capital. However, the energy saving technology's displacement effects might not affect the conditions under which the Harberger-Laursen-Metzler (HLM) effect holds. The effects of rising energy prices on bonds are stronger, and there are more ambiguous instantaneous returns, but the conditions under which the HLM effect holds are different.

The Impact of Sustainable Development Technology on a Small Economy—The Case of Energy-Saving Technology

PubMed Central

Huang, Qinghua; Huang, Weilun; Li, Xue

2018-01-01

We investigated the impact of a sustainable development technology on the macroeconomic variables in a small economy utilizing a case study with a stochastically improving energy saving technology and a stochastically increasing energy price. The results show the technological displacement effects of energy saving technology are stronger, but there are more ambiguous instantaneous returns to physical capital. However, the energy saving technology’s displacement effects might not affect the conditions under which the Harberger-Laursen-Metzler (HLM) effect holds. The effects of rising energy prices on bonds are stronger, and there are more ambiguous instantaneous returns, but the conditions under which the HLM effect holds are different. PMID:29419788

Generalized squeezing rotating-wave approximation to the isotropic and anisotropic Rabi model in the ultrastrong-coupling regime

NASA Astrophysics Data System (ADS)

Zhang, Yu-Yu

2016-12-01

Generalized squeezing rotating-wave approximation (GSRWA) is proposed by employing both the displacement and the squeezing transformations. A solvable Hamiltonian is reformulated in the same form as the ordinary RWA ones. For a qubit coupled to oscillators experiment, a well-defined Schrödinger-cat-like entangled state is given by the displaced-squeezed oscillator state instead of the original displaced state. For the isotropic Rabi case, the mean photon number and the ground-state energy are expressed analytically with additional squeezing terms, exhibiting a substantial improvement of the GSRWA. And the ground-state energy in the anisotropic Rabi model confirms the effectiveness of the GSRWA. Due to the squeezing effect, the GSRWA improves the previous methods only with the displacement transformation in a wide range of coupling strengths even for large atom frequency.

Ab initio molecular dynamics investigations of low-energy recoil events in Ni and NiCo

DOE PAGES

Liu, Bin; Yuan, Fenglin; Jin, Ke; ...

2015-10-06

Low-energy recoil events in pure Ni and the equiatomic NiCo alloy are studied using ab initio molecular dynamics simulations. We found that the threshold displacement energies are strongly dependent on orientation and weakly dependent on composition. The minimum threshold displacement energies are along the [1 1 0] direction in both pure Ni and the NiCo alloy. Compared to pure Ni, the threshold displacement energies increase slightly in the NiCo alloy due to stronger bonds in the alloy, irrespective of the element type of the PKA. A single Ni interstitial occupying the center of a tetrahedron formed by four Ni atomsmore » and a <1 0 0> split interstitial is produced in pure Ni by the recoils, while only the <1 0 0> split interstitial is formed in the NiCo alloy. Compared to the replacement sequences in pure Ni, anti-site defect sequences are observed in the alloy, which have high efficiency for both producing defects and transporting energy outside of the cascade core. These results provide insights into energy transfer processes occurring in equiatomic alloys under irradiation.« less

Photovoltaic frequency–watt curve design for frequency regulation and fast contingency reserves

DOE PAGES

Johnson, Jay; Neely, Jason C.; Delhotal, Jarod J.; ...

2016-09-02

When renewable energy resources are installed in electricity grids, they typically increase generation variability and displace thermal generator control action and inertia. Grid operators combat these emerging challenges with advanced distributed energy resource (DER) functions to support frequency and provide voltage regulation and protection mechanisms. This paper focuses on providing frequency reserves using autonomous IEC TR 61850-90-7 pointwise frequency-watt (FW) functions that adjust DER active power as a function of measured grid frequency. The importance of incorporating FW functions into a fleet of photovoltaic (PV) systems is demonstrated in simulation. Effects of FW curve design, including curtailment, deadband, and droop,more » were analyzed against performance metrics using Latin hypercube sampling for 20%, 70%, and 120% PV penetration scenarios on the Hawaiian island of Lanai. Finally, to understand the financial implications of FW functions to utilities, a performance function was defined based on monetary costs attributable to curtailed PV production, load shedding, and generator wear. An optimization wrapper was then created to find the best FW function curve for each penetration level. Lastly, it was found that in all cases, the utility would save money by implementing appropriate FW functions.« less

[Treatment of metacarpal fractures].

PubMed

Prokop, A; Jubel, A; Helling, H J; Kulus, S; Rehm, K E

2002-09-01

Conservative treatment of metacarpal fractures is recommended if there is no joint displacement, malrotation, displacement of over 30 degrees ad axim and shortening of over 5 mm. Surgery should be performed in open fractures and serial fractures of metacarpal bone. Early functional treatment should be carried out in stable, not displaced fractures. A cast can be used for a short period in full extended position of fingers and flexion in metacarpo-phalangeal joint in 60 - 90 degrees. Twin-tape fixation allows functional treatment after soft-tissue swelling has disappeared. Closed reduction of displaced fractures of the fifth metacarpal bone (boxer's fracture) is not successful. Cases with displacement of over 30 degrees may be treated surgically by intramedullary stabilisation.

Chemical accuracy from quantum Monte Carlo for the benzene dimer.

PubMed

Azadi, Sam; Cohen, R E

2015-09-14

We report an accurate study of interactions between benzene molecules using variational quantum Monte Carlo (VMC) and diffusion quantum Monte Carlo (DMC) methods. We compare these results with density functional theory using different van der Waals functionals. In our quantum Monte Carlo (QMC) calculations, we use accurate correlated trial wave functions including three-body Jastrow factors and backflow transformations. We consider two benzene molecules in the parallel displaced geometry, and find that by highly optimizing the wave function and introducing more dynamical correlation into the wave function, we compute the weak chemical binding energy between aromatic rings accurately. We find optimal VMC and DMC binding energies of -2.3(4) and -2.7(3) kcal/mol, respectively. The best estimate of the coupled-cluster theory through perturbative triplets/complete basis set limit is -2.65(2) kcal/mol [Miliordos et al., J. Phys. Chem. A 118, 7568 (2014)]. Our results indicate that QMC methods give chemical accuracy for weakly bound van der Waals molecular interactions, comparable to results from the best quantum chemistry methods.

Stability Criteria Analysis for Landing Craft Utility

DTIC Science & Technology

2017-12-01

Square meter m/s Meters per Second m/s2 Meters per Second Squared n Vertical Displacement of Sea Water Free Surface n3 Ship’s Heave... Displacement n5 Ship’s Pitch Angle p(ξ) Rayleigh Distribution Probability Function POSSE Program of Ship Salvage Engineering pk...Spectrum Constant γ JONSWAP Wave Spectrum Peak Factor Γ(λ) Gamma Probability Function Δ Ship’s Displacement Δω Small Frequency

KRASH 85 User’s Guide - Input/Output Format.

DTIC Science & Technology

1985-07-01

speaking, any significant .crror in the model will result in a very large value for EPSILON (1>0.1) or will ca;use the NASTRAN solution to terminate with...with NASTRAN ) * A comprehensive energy balance, * Center of gravity (c.g.) displacement, velocity, acceleration and force time histories * Revised...initial conditions subroutine (combined with NASTRAN ) * A comprehensive energy balance * Center of gravity (e.g.) displacement, velocity, acceleration and

Pelvic trauma with displaced sacral fractures: functional outcome at one year.

PubMed

Tötterman, Anna; Glott, Thomas; Søberg, Helene Lundgaard; Madsen, Jan Erik; Røise, Olav

2007-06-01

A prospective single-cohort study of 31 patients surgically treated for pelvic injuries with displaced sacral fractures. To describe the medium term functional outcome in unstable sacral fractures. Displaced sacral fractures pose a special challenge in orthopedic surgery due to the high rate of associated injuries. Little information is available on the medium-term functional outcome of patients with injuries which include unstable sacral fractures. We examined 31 patients with displaced sacral fractures having 10 mm or more displacement, 1 year (mean, 1.4 years; range, 1.0-2.5 years) after injury. Data from a previous study were supplemented with functional outcome measures (work status, independence in ADL, and SF-36). An association between outcome and tested variables was sought. Fifteen months after injury, 65% of the patients had regained their independence in functions pertaining to daily activities; 33% had returned to work. All dimensions of perceived health were affected. Polytrauma and impairments relative to voiding and sexual function had a detrimental effect on outcome. Fracture characteristics were not predictive of poor outcome. Although the majority of patients achieved independent living, medium-term follow-up indicated significant residual disability. The complex nature of these fractures and the associated injuries should be considered in the rehabilitation of these patients.

Ab initio molecular dynamics simulations of low energy recoil events in MgO

NASA Astrophysics Data System (ADS)

Petersen, B. A.; Liu, B.; Weber, W. J.; Zhang, Y.

2017-04-01

Low-energy recoil events in MgO are studied using ab intio molecular dynamics simulations to reveal the dynamic displacement processes and final defect configurations. Threshold displacement energies, Ed, are obtained for Mg and O along three low-index crystallographic directions, [100], [110], and [111]. The minimum values for Ed are found along the [110] direction consisting of the same element, either Mg or O atoms. Minimum threshold values of 29.5 eV for Mg and 25.5 eV for O, respectively, are suggested from the calculations. For other directions, the threshold energies are considerably higher, 65.5 and 150.0 eV for O along [111] and [100], and 122.5 eV for Mg along both [111] and [100] directions, respectively. These results show that the recoil events in MgO are partial-charge transfer assisted processes where the charge transfer plays an important role. There is a similar trend found in other oxide materials, where the threshold displacement energy correlates linearly with the peak partial-charge transfer, suggesting this behavior might be universal in ceramic oxides.

Adsorption, desorption, and displacement kinetics of H2O and CO2 on TiO2(110).

PubMed

Smith, R Scott; Li, Zhenjun; Chen, Long; Dohnálek, Zdenek; Kay, Bruce D

2014-07-17

The adsorption, desorption, and displacement kinetics of H2O and CO2 on TiO2(110) are investigated using temperature programmed desorption (TPD) and molecular beam techniques. The TPD spectra for both H2O and CO2 have well-resolved peaks corresponding to desorption from bridge-bonded oxygen (Ob), Ti5c, and defect sites in order of increasing peak temperature. Analysis of the saturated surface spectrum for both species reveals that the corresponding adsorption energies on all sites are greater for H2O than for CO2. Sequential dosing of H2O and CO2 reveals that, independent of the dose order, H2O molecules will displace CO2 in order to occupy the highest energy binding sites available. Isothermal experiments show that the displacement of CO2 by H2O occurs between 75 and 80 K.

On the strain energy of laminated composite plates

NASA Technical Reports Server (NTRS)

Atilgan, Ali R.; Hodges, Dewey H.

1991-01-01

The present effort to obtain the asymptotically correct form of the strain energy in inhomogeneous laminated composite plates proceeds from the geometrically nonlinear elastic theory-based three-dimensional strain energy by decomposing the nonlinear three-dimensional problem into a linear, through-the-thickness analysis and a nonlinear, two-dimensional analysis analyzing plate formation. Attention is given to the case in which each lamina exhibits material symmetry about its middle surface, deriving closed-form analytical expressions for the plate elastic constants and the displacement and strain distributions through the plate's thickness. Despite the simplicity of the plate strain energy's form, there are no restrictions on the magnitudes of displacement and rotation measures.

Evaluating Interventions in the U.S. Electricity System: Assessments of Energy Efficiency, Renewable Energy, and Small-Scale Cogeneration

NASA Astrophysics Data System (ADS)

Siler-Evans, Kyle

There is growing interest in reducing the environmental and human-health impacts resulting from electricity generation. Renewable energy, energy efficiency, and energy conservation are all commonly suggested solutions. Such interventions may provide health and environmental benefits by displacing emissions from conventional power plants. However, the generation mix varies considerably from region to region and emissions vary by the type and age of a generator. Thus, the benefits of an intervention will depend on the specific generators that are displaced, which vary depending on the timing and location of the intervention. Marginal emissions factors (MEFs) give a consistent measure of the avoided emissions per megawatt-hour of displaced electricity, which can be used to evaluate the change in emissions resulting from a variety of interventions. This thesis presents the first systematic calculation of MEFs for the U.S. electricity system. Using regressions of hourly generation and emissions data from 2006 through 2011, I estimate regional MEFs for CO2, NO x, and SO2, as well as the share of marginal generation from coal-, gas-, and oil-fired generators. This work highlights significant regional differences in the emissions benefits of displacing a unit of electricity: compared to the West, displacing one megawatt-hour of electricity in the Midwest is expected to avoid roughly 70% more CO2, 12 times more SO 2, and 3 times more NOx emissions. I go on to explore regional variations in the performance of wind turbines and solar panels, where performance is measured relative to three objectives: energy production, avoided CO2 emissions, and avoided health and environmental damages from criteria pollutants. For 22 regions of the United States, I use regressions of historic emissions and generation data to estimate marginal impact factors, a measure of the avoided health and environmental damages per megawatt-hour of displaced electricity. Marginal impact factors are used to evaluate the effects of an additional wind turbine or solar panel in the U.S. electricity system. I find that the most attractive sites for renewables depend strongly on one's objective. A solar panel in Iowa displaces 20% more CO2 emissions than a panel in Arizona, though energy production from the Iowa panel is 25% less. Similarly, despite a modest wind resource, a wind turbine in West Virginia is expected to displace 7 times more health and environmental damages than a wind turbine in Oklahoma. Finally, I shift focus and explore the economics of small-scale cogeneration, which has long been recognized as a more efficient alternative to central-station power. Although the benefits of distributed cogeneration are widely cited, adoption has been slow in the U.S. Adoption could be encouraged by making cogeneration more economically attractive, either by increasing the expected returns or decreasing the risks of such investments. I present a case study of a 300-kilowatt cogeneration unit and evaluate the expected returns from: demand response, capacity markets, regulation markets, accelerated depreciation, a price on CO2 emissions, and net metering. In addition, I explore the effectiveness of feed-in tariffs at mitigating the energy-price risks to cogeneration projects.

Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Yanfei; Larson, Ben C.

There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown thatmore » the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.« less

Displacement Fields and Self-Energies of Circular and Polygonal Dislocation Loops in Homogeneous and Layered Anisotropic Solids

DOE PAGES

Gao, Yanfei; Larson, Ben C.

2015-06-19

There are large classes of materials problems that involve the solutions of stress, displacement, and strain energy of dislocation loops in elastically anisotropic solids, including increasingly detailed investigations of the generation and evolution of irradiation induced defect clusters ranging in sizes from the micro- to meso-scopic length scales. Based on a two-dimensional Fourier transform and Stroh formalism that are ideal for homogeneous and layered anisotropic solids, we have developed robust and computationally efficient methods to calculate the displacement fields for circular and polygonal dislocation loops. Using the homogeneous nature of the Green tensor of order -1, we have shown thatmore » the displacement and stress fields of dislocation loops can be obtained by numerical quadrature of a line integral. In addition, it is shown that the sextuple integrals associated with the strain energy of loops can be represented by the product of a pre-factor containing elastic anisotropy effects and a universal term that is singular and equal to that for elastic isotropic case. Furthermore, we have found that the self-energy pre-factor of prismatic loops is identical to the effective modulus of normal contact, and the pre-factor of shear loops differs from the effective indentation modulus in shear by only a few percent. These results provide a convenient method for examining dislocation reaction energetic and efficient procedures for numerical computation of local displacements and stresses of dislocation loops, both of which play integral roles in quantitative defect analyses within combined experimental–theoretical investigations.« less

Simulation of magnetoelastic response of iron nanowire loop

NASA Astrophysics Data System (ADS)

Huang, Junping; Peng, Xianghe; Wang, Zhongchang; Hu, Xianzhi

2018-03-01

We analyzed the magnetoelastic responses of one-dimensional iron nanowire loop systems with quantum statistical mechanics, treating the particles in the systems as identical bosons with an arbitrary integer spin. Under the assumptions adopted, we demonstrated that the Hamiltonian of the system can be separated into two parts, corresponding to two Ising subsystems, describing the particle spin and the particle displacement, respectively. Because the energy of the particle motion at atomic scale is quantized, there should be more the strict constraint on the particle displacement Ising subsystem. Making use of the existing results for Ising system, the partition function of the system was derived into two parts, corresponding respectively to the two Ising subsystems. Then the Gibbs distribution was obtained by statistical mechanics, and the description for the magnetoelastic response was derived. The magnetoelastic responses were predicted with the developed approach, and the comparison with the results calculated with VASP demonstrates the validity of the developed approach.

A geometrically nonlinear theory of elastic plates

NASA Technical Reports Server (NTRS)

Hodges, Dewey H.; Atilgan, Ali R.; Danielson, D. A.

1992-01-01

A set of kinematic and intrinsic equilibrium equations is derived for plates undergoing large deflection and rotation but with small strain. The large rotation is treated by the general finite rotation of a frame in which the material points that are originally along a normal line in the undeformed plate undergo only small displacements. Exact intrinsic virtual strain-displacement relations are derived; using a reduced 2-D strain energy function from which the warping has been systematically eliminated, a set of intrinsic equilibrium equations follows. It is demonstrated that only five equilibrium equations can be derived in this way, because the component of virtual rotation about the normal is not independent. These equations include terms which cannot be obtained without the use of a finite rotation vector which contains three nonzero components. These extra terms correspond to the difference of in-plane shear stress resultants in other theories.

Adsorption, Desorption, and Displacement Kinetics of H2O and CO2 on TiO2(110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R. Scott; Li, Zhenjun; Chen, Long

The adsorption, desorption, and displacement kinetics of H2O and CO2 on TiO2(110) are investigated using temperature programmed desorption (TPD) and molecular beam techniques. The TPD spectra for both H2O and CO2 have well-resolved peaks corresponding to desorption from bridge-bonded oxygen (BBO), Ti, and oxygen vacancies (VO) sites in order of increasing peak temperature. Analysis of the saturated monolayer peak for both species reveals that the corresponding adsorption energies on all sites are greater for H2O and for CO2. Sequential dosing of H2O and CO2 reveals that, independent of the dose order, H2O molecules will displace CO2 in order to occupymore » the highest energy binding sites available. Isothermal experiments show that the displacement of CO2 by H2O occurs between 75 and 80 K. Further analysis shows that a ratio of 4 H2O to 3 CO2 molecules is needed to displace CO2 from the TiO2(110) surface.« less

Adsorption, Desorption, and Displacement Kinetics of H2O and CO2 on Forsterite, Mg2SiO4(011)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, R. Scott; Li, Zhenjun; Dohnalek, Zdenek

We have examined the adsorbate-substrate interaction kinetics of CO2 and H2O on a natural forsterite crystal surface, Mg2SiO4(011), with 10-15% of substitutional Fe2+. We use temperature programmed desorption (TPD) and molecular beam techniques to determine the adsorption, desorption, and displacement kinetics for H2O and CO2. Neither CO2 nor H2O has distinct sub-monolayer desorption peaks but instead both have a broad continuous desorption feature that evolve smoothly into multilayer desorption. Inversion of the monolayer coverage spectra for both molecules reveals that the corresponding binding energies for H2O are greater than that for CO2 on all sites. The relative strength of thesemore » interactions is the dominant factor in the competitive adsorption/displacement kinetics. In experiments where the two adsorbates are co-dosed, H2O always binds to the highest energy binding sites available and displaces CO2. The onset of CO2 displacement by H2O occurs between 65 and 75 K.« less

First-principles studies of PETN molecular crystal vibrational frequencies under high pressure

NASA Astrophysics Data System (ADS)

Perger, Warren; Zhao, Jijun

2005-07-01

The vibrational frequencies of the PETN molecular crystal were calculated using the first-principles CRYSTAL03 program which employs an all-electron LCAO approach and calculates analytic first derivatives of the total energy with respect to atomic displacements. Numerical second derivatives were used to enable calculation of the vibrational frequencies at ambient pressure and under various states of compression. Three different density functionals, B3LYP, PW91, and X3LYP were used to examine the effect of the exchange-correlation functional on the vibrational frequencies. The pressure-induced shift of the vibrational frequencies will be presented and compared with experiment. The average deviation with experimental results is shown to be on the order of 2-3%, depending on the functional used.

The Wrinkling of a Twisted Ribbon

NASA Astrophysics Data System (ADS)

Kohn, Robert V.; O'Brien, Ethan

2018-02-01

Recent experiments by Chopin and Kudrolli (Phys Rev Lett 111:174302, 2013) showed that a thin elastic ribbon, when twisted into a helicoid, may wrinkle in the center. We study this from the perspective of elastic energy minimization, building on recent work by Chopin et al. (J Elast 119(1-2):137-189, 2015) in which they derive a modified von Kármán functional and solve the relaxed problem. Our main contribution is to show matching upper and lower bounds for the minimum energy in the small-thickness limit. Along the way, we show that the displacements must be small where we expect that the ribbon is helicoidal, and we estimate the wavelength of the wrinkles.

Correlation of a Bipolar-Transistor-Based Neutron Displacement Damage Sensor Methodology with Proton Irradiations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tonigan, Andrew M.; Arutt, Charles N.; Parma, Edward J.

For this research, a bipolar-transistor-based sensor technique has been used to compare silicon displacement damage from known and unknown neutron energy spectra generated in nuclear reactor and high-energy-density physics environments. The technique has been shown to yield 1-MeV(Si) equivalent neutron fluence measurements comparable to traditional neutron activation dosimetry. This study significantly extends previous results by evaluating three types of bipolar devices utilized as displacement damage sensors at a nuclear research reactor and at a Pelletron particle accelerator. Ionizing dose effects are compensated for via comparisons with 10-keV x-ray and/or cobalt-60 gamma ray irradiations. Non-ionizing energy loss calculations adequately approximate themore » correlations between particle-device responses and provide evidence for the use of one particle type to screen the sensitivity of the other.« less

Correlation of a Bipolar-Transistor-Based Neutron Displacement Damage Sensor Methodology with Proton Irradiations

DOE PAGES

Tonigan, Andrew M.; Arutt, Charles N.; Parma, Edward J.; ...

2017-11-16

For this research, a bipolar-transistor-based sensor technique has been used to compare silicon displacement damage from known and unknown neutron energy spectra generated in nuclear reactor and high-energy-density physics environments. The technique has been shown to yield 1-MeV(Si) equivalent neutron fluence measurements comparable to traditional neutron activation dosimetry. This study significantly extends previous results by evaluating three types of bipolar devices utilized as displacement damage sensors at a nuclear research reactor and at a Pelletron particle accelerator. Ionizing dose effects are compensated for via comparisons with 10-keV x-ray and/or cobalt-60 gamma ray irradiations. Non-ionizing energy loss calculations adequately approximate themore » correlations between particle-device responses and provide evidence for the use of one particle type to screen the sensitivity of the other.« less

Nonlinear Stability and Saturation of Ballooning Modes in Tokamaks*

NASA Astrophysics Data System (ADS)

Ham, C. J.; Cowley, S. C.; Brochard, G.; Wilson, H. R.

2016-06-01

The theory of tokamak stability to nonlinear "ballooning" displacements of elliptical magnetic flux tubes is presented. Above a critical pressure profile the energy stored in the plasma may be lowered by finite (but not infinitesimal) displacements of such tubes (metastability). Above a higher pressure profile, the linear stability boundary, such tubes are linearly and nonlinearly unstable. The predicted saturated flux tube displacement can be of the order of the pressure gradient scale length. Plasma transport from these displaced flux tubes may explain the rapid loss of confinement in some experiments.

Visualizing the orientational dependence of an intermolecular potential

NASA Astrophysics Data System (ADS)

Sweetman, Adam; Rashid, Mohammad A.; Jarvis, Samuel P.; Dunn, Janette L.; Rahe, Philipp; Moriarty, Philip

2016-02-01

Scanning probe microscopy can now be used to map the properties of single molecules with intramolecular precision by functionalization of the apex of the scanning probe tip with a single atom or molecule. Here we report on the mapping of the three-dimensional potential between fullerene (C60) molecules in different relative orientations, with sub-Angstrom resolution, using dynamic force microscopy (DFM). We introduce a visualization method which is capable of directly imaging the variation in equilibrium binding energy of different molecular orientations. We model the interaction using both a simple approach based around analytical Lennard-Jones potentials, and with dispersion-force-corrected density functional theory (DFT), and show that the positional variation in the binding energy between the molecules is dominated by the onset of repulsive interactions. Our modelling suggests that variations in the dispersion interaction are masked by repulsive interactions even at displacements significantly larger than the equilibrium intermolecular separation.

Low energy proton irradiation effects on InP/InGaAs DHBTs and InP-base frequency dividers

NASA Astrophysics Data System (ADS)

Zhang, Xingyao; Li, Yudong; Guo, Qi; Feng, Jie

2018-03-01

InP/InGaAs DHBTs and frequency dividers are irradiated by low energy proton, and displacement damage effect of the devices are analyzed. InP/InGaAs DHBTs has been made DC characteristics measurements, and the function measurement for frequency dividers has been done both before and after proton irradiation. The breakdown voltage of InP DHBTs drop to 3.7V When the fluence up to 5x1013 protons/cm2. Meanwhile, the function of frequency dividers get out of order. Degradation of DC characteristics of DHBTs are due to the radiation-induced defects in the quasi neutral base and the space charge region of base-collector and base-emitter junctions. The performance deterioration of DHBTs induce the fault of frequency dividers, and prescaler may be the most sensitive circuit.

The impact of displacement on the expression of depressive disorder and social functioning among the war refugees.

PubMed

Radanović-Grgurić, Ljiljana; Barkić, Jelena; Filaković, Pavo; Koić, Oliver; Laufer, Davor; Petek, Anamarija; Mandić, Nikola

2009-12-01

Our research objective was to estimate the characteristics of major depressive disorder and social adaptation of women displaced during the war in Croatia in the early 1990s. We aimed to establish the relationship between major depressive disorder and displacement and study its impact on the outcome of depression in order to improve treatment and avoid possible complications. A group of 20 women, 35 to 55 years of age, displaced some time during the 199l.-1995. war in Croatia were compared to 27 women of the same age but with no experience of exile. All the patients suffered from major depressive disorder based upon DSM-IV diagnostic criteria. The Hamilton Rating Scale for Depression, the Zung Self Rating Depression Scale and the Social Adaptation Self-evaluation Scale were used. The objective intensity of depression of the displaced significantly decreased over time but not their personal experience of depression. All depressed patients manifested poor social adaptation. Many aspects of social functioning remained poor even after the improvement of depressive disorder. Displacement characteristics were: the length of time spent in exile, the place, and the circumstances of displacement regarding the members of the family accompanying the displaced women. These characteristics significantly influenced the expression of their major depressive disorder as well as social functioning. Displaced persons/refugees are at high risk of developing depressive disorder. Recognition of all risk factors and early diagnosis of depressive disorder followed by appropriate treatment could decrease the risk of chronic and complicated depression as well as the risk of poor social adaptation.

Summary of Seismic Discrimination and Explosion Yield Determination Research

DTIC Science & Technology

1978-11-01

measured and nuemrically simulated displacements .. ........... ... 56 21 Comparison of experimental and numerically simulated source functions expressed...as RVP transforms ...... ..................... 5 22 Comparison of measured and predicted displace- ments for Test 1 ..... .............. ... 57 23...Comparison of measured and predicted displace- ments for the cratering shot (Test 8) . . . . 59 24 The vertical displacement from the complete two

Crystal water dynamics of guanosine dihydrate: analysis of atomic displacement parameters, time profile of hydrogen-bonding probability, and translocation of water by MD simulation.

PubMed

Yoneda, Shigetaka; Sugawara, Yoko; Urabe, Hisako

2005-01-27

The dynamics of crystal water molecules of guanosine dihydrate are investigated in detail by molecular dynamics (MD) simulation. A 2 ns simulation is performed using a periodic boundary box composed of 4 x 5 x 8 crystallographic unit cells and using the particle-mesh Ewald method for calculation of electrostatic energy. The simulated average atomic positions and atomic displacement parameters are remarkably coincident with the experimental values determined by X-ray analysis, confirming the high accuracy of this simulation. The dynamics of crystal water are analyzed in terms of atomic displacement parameters, orientation vectors, order parameters, self-correlation functions of the orientation vectors, time profiles of hydrogen-bonding probability, and translocations. The simulation clarifies that the average structure is composed of various stable and transient structures of the molecules. The simulated guanosine crystal forms a layered structure, with four water sites per asymmetric unit, classified as either interlayer water or intralayer water. From a detailed analysis of the translocations of water molecules in the simulation, columns of intralayer water molecules along the c axis appear to represent a pathway for hydration and dehydration by a kind of molecular valve mechanism.

Isospin-symmetry breaking in masses of N ≃ Z nuclei

NASA Astrophysics Data System (ADS)

Bączyk, P.; Dobaczewski, J.; Konieczka, M.; Satuła, W.; Nakatsukasa, T.; Sato, K.

2018-03-01

Effects of the isospin-symmetry breaking (ISB) beyond mean-field Coulomb terms are systematically studied in nuclear masses near the N = Z line. The Coulomb exchange contributions are calculated exactly. We use extended Skyrme energy density functionals (EDFs) with proton-neutron-mixed densities, to which we add new terms breaking the isospin symmetry. Two parameters associated with the new terms are determined by fitting mirror and triplet displacement energies (MDEs and TDEs) of isospin multiplets. The new EDFs reproduce MDEs for the T = 1/2 doublets and T = 1 triplets, and TDEs for the T = 1 triplets. Relative strengths of the obtained isospin-symmetry-breaking terms are not consistent with the differences in the NN scattering lengths, ann, app, and anp. Based on low-energy experimental data, it seems thus impossible to delineate the strong-force ISB effects from beyond-mean-field Coulomb-energy corrections.

How main-chains of proteins explore the free-energy landscape in native states.

PubMed

Senet, Patrick; Maisuradze, Gia G; Foulie, Colette; Delarue, Patrice; Scheraga, Harold A

2008-12-16

Understanding how a single native protein diffuses on its free-energy landscape is essential to understand protein kinetics and function. The dynamics of a protein is complex, with multiple relaxation times reflecting a hierarchical free-energy landscape. Using all-atom molecular dynamics simulations of an alpha/beta protein (crambin) and a beta-sheet polypeptide (BS2) in their "native" states, we demonstrate that the mean-square displacement of dihedral angles, defined by 4 successive C(alpha) atoms, increases as a power law of time, t(alpha), with an exponent alpha between 0.08 and 0.39 (alpha = 1 corresponds to Brownian diffusion), at 300 K. Residues with low exponents are located mainly in well-defined secondary elements and adopt 1 conformational substate. Residues with high exponents are found in loops/turns and chain ends and exist in multiple conformational substates, i.e., they move on multiple-minima free-energy profiles.

How main-chains of proteins explore the free-energy landscape in native states

PubMed Central

Senet, Patrick; Maisuradze, Gia G.; Foulie, Colette; Delarue, Patrice; Scheraga, Harold A.

2008-01-01

Understanding how a single native protein diffuses on its free-energy landscape is essential to understand protein kinetics and function. The dynamics of a protein is complex, with multiple relaxation times reflecting a hierarchical free-energy landscape. Using all-atom molecular dynamics simulations of an α/β protein (crambin) and a β-sheet polypeptide (BS2) in their “native” states, we demonstrate that the mean-square displacement of dihedral angles, defined by 4 successive Cα atoms, increases as a power law of time, tα, with an exponent α between 0.08 and 0.39 (α = 1 corresponds to Brownian diffusion), at 300 K. Residues with low exponents are located mainly in well-defined secondary elements and adopt 1 conformational substate. Residues with high exponents are found in loops/turns and chain ends and exist in multiple conformational substates, i.e., they move on multiple-minima free-energy profiles. PMID:19073932

EFFECT OF STRAIN FIELD ON THRESHOLD DISPLACEMENT ENERGY OF TUNGSTEN STUDIED BY MOLECULAR DYNAMICS SIMULATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, D.; Gao, Ning; Setyawan, Wahyu

The influence of hydrostatic strain on point defect formation energy and threshold displacement energy (Ed) in body-centered cubic (BCC) tungsten was studied with molecular dynamics simulations. Two different tungsten potentials (Fikar and Juslin) were used. The minimum Ed direction calculated with the Fikar-potential was <100>, but with the Juslin-potential it was <111>. The most stable self-interstitial (SIA) configuration was a <111>-crowdion for both potentials. The stable SIA configuration did not change with applied strain. Varying the strain from compression to tension increased the vacancy formation energy but decreased the SIA formation energy. The SIA formation energy changed more significantly thanmore » for a vacancy such that Ed decreased with applied strain from compression to tension.« less

Elastic Model Transitions: A Hybrid Approach Utilizing Quadratic Inequality Constrained Least Squares (LSQI) and Direct Shape Mapping (DSM)

NASA Technical Reports Server (NTRS)

Hannan, Mike R.; Jurenko, Robert J.; Bush, Jason; Ottander, John

2014-01-01

A method for transitioning linear time invariant (LTI) models in time varying simulation is proposed that utilizes a hybrid approach for determining physical displacements by augmenting the original quadratically constrained least squares (LSQI) algorithm with Direct Shape Mapping (DSM) and modifying the energy constraints. The approach presented is applicable to simulation of the elastic behavior of launch vehicles and other structures that utilize discrete LTI finite element model (FEM) derived mode sets (eigenvalues and eigenvectors) that are propagated throughout time. The time invariant nature of the elastic data presents a problem of how to properly transition elastic states from the prior to the new model while preserving motion across the transition and ensuring there is no truncation or excitation of the system. A previous approach utilizes a LSQI algorithm with an energy constraint to effect smooth transitions between eigenvector sets with no requirement that the models be of similar dimension or have any correlation. This approach assumes energy is conserved across the transition, which results in significant non-physical transients due to changing quasi-steady state energy between mode sets, a phenomenon seen when utilizing a truncated mode set. The computational burden of simulating a full mode set is significant so a subset of modes is often selected to reduce run time. As a result of this truncation, energy between mode sets may not be constant and solutions across transitions could produce non-physical transients. In an effort to abate these transients an improved methodology was developed based on the aforementioned approach, but this new approach can handle significant changes in energy across mode set transitions. It is proposed that physical velocities due to elastic behavior be solved for using the LSQI algorithm, but solve for displacements using a two-step process that independently addresses the quasi-steady-state and non-steady-state contributions to the elastic displacement. For structures subject to large external forces, such as thrust or atmospheric drag, it is imperative to capture these forces when solving for elastic displacement. To simplify the mathematical formulation, assumptions are made regarding mass matrix normalization, constant external forcing, and constant viscous damping. These simplifications allow for direct solutions to the quasi-steady-state displacements through a process titled Direct Shape Mapping. DSM solves for the displacements using the eigenvalues of the elastic modes and the external forcing and returns a set of elastic displacements dictated by the eigenvectors of the post-transition mode set. For the non-steady-state contributions to displacement we formulate a LSQI problem that is constrained by energy of the non-steady state terms. The contributions from the quasi-steady-state and non-steady state solutions are then combined to obtain the physical displacements associated with the new set of eigenvectors. Results for the LSQI-DSM approach show significant reduction/complete removal of transients across mode set transitions while maintaining elastic motion from the prior state. For time propagation applications employing discrete elastic models that need to be transitioned in time and where running with full a full mode set is not feasible, the method developed offers a practical solution to simulating vehicle elasticity.

Computer Simulation of a 155-mm Projectile in a Scat Gun Assembly

DTIC Science & Technology

2008-09-01

piston increases its kinetic energy as it is displaced a distance X. X X X MpsV2s /2 = f((P- vRT )/(Lpw -X))A - F)dx = (- vRT /(Lpw - X))AdY + f(PA -F...piston is displaced x, the critical displacement can be calculated using the Ideal Gas Law PV = vRT . YD = vRT /(A(Lp;v - x,i)) (ALpwv - x(,.ij

Automated generation of influence functions for planar crack problems

NASA Technical Reports Server (NTRS)

Sire, Robert A.; Harris, David O.; Eason, Ernest D.

1989-01-01

A numerical procedure for the generation of influence functions for Mode I planar problems is described. The resulting influence functions are in a form for convenient evaluation of stress-intensity factors for complex stress distributions. Crack surface displacements are obtained by a least-squares solution of the Williams eigenfunction expansion for displacements in a cracked body. Discrete values of the influence function, evaluated using the crack surface displacements, are curve fit using an assumed functional form. The assumed functional form includes appropriate limit-behavior terms for very deep and very shallow cracks. Continuous representation of the influence function provides a convenient means for evaluating stress-intensity factors for arbitrary stress distributions by numerical integration. The procedure is demonstrated for an edge-cracked strip and a radially cracked disk. Comparisons with available published results demonstrate the accuracy of the procedure.

Large-amplitude jumps and non-Gaussian dynamics in highly concentrated hard sphere fluids.

PubMed

Saltzman, Erica J; Schweizer, Kenneth S

2008-05-01

Our microscopic stochastic nonlinear Langevin equation theory of activated dynamics has been employed to study the real-space van Hove function of dense hard sphere fluids and suspensions. At very short times, the van Hove function is a narrow Gaussian. At sufficiently high volume fractions, such that the entropic barrier to relaxation is greater than the thermal energy, its functional form evolves with time to include a rapidly decaying component at small displacements and a long-range exponential tail. The "jump" or decay length scale associated with the tail increases with time (or particle root-mean-square displacement) at fixed volume fraction, and with volume fraction at the mean alpha relaxation time. The jump length at the alpha relaxation time is predicted to be proportional to a measure of the decoupling of self-diffusion and structural relaxation. At long times corresponding to mean displacements of order a particle diameter, the volume fraction dependence of the decay length disappears. A good superposition of the exponential tail feature based on the jump length as a scaling variable is predicted at high volume fractions. Overall, the theoretical results are in good accord with recent simulations and experiments. The basic aspects of the theory are also compared with a classic jump model and a dynamically facilitated continuous time random-walk model. Decoupling of the time scales of different parts of the relaxation process predicted by the theory is qualitatively similar to facilitated dynamics models based on the concept of persistence and exchange times if the elementary event is assumed to be associated with transport on a length scale significantly smaller than the particle size.

Comparative study of displacement cascades simulated with 'magnetic' potentials and Mendelev-type potential in α-Fe

NASA Astrophysics Data System (ADS)

Gao, Chan; Tian, Dongfeng; Li, Maosheng; Qian, Dazhi

2017-04-01

Different interatomic potentials produce displacement cascades with different features, and hence they significantly influence the results obtained from the displacement cascade simulations. The displacement cascade simulations in α-Fe have been carried out by molecular dynamics with three 'magnetic' potentials (MP) and Mendelev-type potential in this paper. Prior to the cascade simulations, the 'magnetic' potentials are hardened to suit for cascade simulations. We find that the peak time, maximum of defects, cascade volume and cascade density with 'magnetic' potentials are smaller than those with Mendelev-type potential. There is no significant difference within statistical uncertainty in the defect production efficiency with Mendelev-type potential and the second 'magnetic' potential at the same cascade energy, but remarkably smaller than those with the first and third 'magnetic' potential. Self interstitial atom (SIA) clustered fractions with 'magnetic' potentials are smaller than that with Mendelev-type potential, especially at the higher energy, due to the larger interstitial formation energies which result from the 'magnetic' potentials. The defect clustered fractions, which are input data for radiation damage accumulation models, may influence the prediction of microstructural evolution under radiation.

Apparatus and method for suppressing vibration and displacement of a bellows

DOEpatents

Kuklo, T.C.

1984-01-01

Flexible bellows are utilized between two systems, such as a pumping system and a process station, to partially absorb system vibrations and to compensate for misalignment between the systems. It is common practice to either clamp a rigid spacer between flanges of the two systems to separate them from each other, or to maintain the bellows in unsupported relationship between these systems. In the former bellows arrangement, the rigid spacer transmits vibratory energy between the two systems and the bellows tends to function as an undamped or underdamped unit that resonates at its own frequency to create additional vibratory energy, transmitted to the systems. In the latter, unsupported bellows arrangement, the pressure differential prevalent between the fluid flowing through the bellows and ambient normally causes extension or retraction of the bellows and resulting misalignment problems. The present invention substantially solves the above vibration and misalignment problems by providing an inflatable tube in surrounding relationship about a bellows to suppress vibration and displacement thereof. A method for isolating first and second systems from each other to prevent the transmission of vibratory energy therebetween comprises the steps of attaching at least one flexible bellows between the systems, surrounding the bellows with an inflatable tube, and maintaining a predetermined pressure in the tube to urge the tube in flexible contact with at least some of the convolutions of the bellows.

Fault Gauge Numerical Simulation : Dynamic Rupture Propagation and Local Energy Partitioning

NASA Astrophysics Data System (ADS)

Mollon, G.

2017-12-01

In this communication, we present dynamic simulations of the local (centimetric) behaviour of a fault filled with a granular gauge submitted to dynamic rupture. The numerical tool (Fig. 1) combines classical Discrete Element Modelling (albeit with the ability to deal with arbitrary grain shapes) for the simualtion of the gauge, and continuous modelling for the simulation of the acoustic waves emission and propagation. In a first part, the model is applied to the simulation of steady-state shearing of the fault under remote displacement boudary conditions, in order to observe the shear accomodation at the interface (R1 cracks, localization, wear, etc.). It also makes it possible to fit to desired values the Rate and State Friction properties of the granular gauge by adapting the contact laws between grains. Such simulations provide quantitative insight in the steady-state energy partitionning between fracture, friction and acoustic emissions as a function of the shear rate. In a second part, the model is submitted to dynamic rupture. For that purpose, the fault is elastically preloaded just below rupture, and a displacement pulse is applied at one end of the sample (and on only one side of the fault). This allows to observe the propagation of the instability along the fault and the interplay between this propagation and the local granular phenomena. Energy partitionning is then observed both in space and time.

Modeling of normal contact of elastic bodies with surface relief taken into account

NASA Astrophysics Data System (ADS)

Goryacheva, I. G.; Tsukanov, I. Yu

2018-04-01

An approach to account the surface relief in normal contact problems for rough bodies on the basis of an additional displacement function for asperities is considered. The method and analytic expressions for calculating the additional displacement function for one-scale and two-scale wavy relief are presented. The influence of the microrelief geometric parameters, including the number of scales and asperities density, on additional displacements of the rough layer is analyzed.

A novel determination of energy expenditure efficiency during a balance task using accelerometers. A pilot study.

PubMed

Caña-Pino, Alejandro; Apolo-Arenas, Maria Dolores; Moral-Blanco, Javier; De la Cruz-Sánchez, Ernesto; Espejo-Antúnez, Luis

2017-08-18

The objectives of this study are to determine the displacement of the center of pressure (CoP) and its association with the spectral energy density of the acceleration required for the maintenance of postural balance in different standing positions in healthy participants using design observational and setting laboratorial studies. Participants were 30 healthy university students aged between 18 and 32 years old (mean [M] ± standard deviation [SD] = 21,57 ± 3,31 years). Triaxial accelerometer and a pressure platform were used in order to obtain energy spectral density and CoP sway measurements during four balance tasks. Statistically significant differences were found for anteroposterior (p = 0.002) and mediolateral (p = 0.009) CoP displacement between the conditions eyes closed and stable surface and the conditions eyes closed and unstable surface. A statistically significant correlation was also observed between Z-axis (anterior-posterior) of the accelerometer and mediolateral axis of the CoP (r = 0.465; p = 0.01) and between Y-axis accelerometer (mediolateral) and displacement of the CoP in the anteroposterior axis (r = 0.413; p = 0.023). Spectral energy density appears to be associated with the displacement of CoP in healthy participants.

Pre- and postoperative magnetic resonance imaging appearance of the normal residual pituitary gland following macroadenoma resection: Clinical implications

PubMed Central

Maio, Salvatore Di; Biswas, Arundhati; Vézina, Jean Lorrain; Hardy, Jules; Mohr, Gérard

2012-01-01

Background: To assess the relationship between the preoperative magnetic resonance imaging (MRI) appearance of the normal residual pituitary gland (NRPG) and pituitary functional outcome following transsphenoidal resection of pituitary macroadenomas. Methods: We retrospectively reviewed the medical records of 100 consecutive patients with a pituitary macroadenoma, who underwent transsphenoidal resection. The preoperative configuration of the displaced NRPG was stratified as superior, superolateral or lateral. The extent of postoperative restitution of the NRPG was divided into four groups: Group 1 — normal residual gland or almost normal; Group 2 — more than 50% restitution; Group 3 — less than 50% of the normal residual gland; and Group 4 — barely visible or absent residual gland. The pre- and postoperative NRPG appearance was correlated with pituitary functional status. Results: Preoperatively, the NRPG was identifiable in 79 patients, with extrasellar displacement in 53%. The displacement pattern was superior in 8%, superolateral in 32%, and lateral in 58% of the patients. If the NRPG was displaced laterally, the ipsilateral cavernous sinus was not invaded by the pituitary macroadenoma. Partial or complete pituitary function was lost in 6 / 23 (26.1%) patients with superior or superolateral displacement of the NRPG, compared to only 1 / 36 (2.8%) patients without superior displacement of the NRPG (P = 0.025). Progressive postoperative reconstitution of the NRPG was related to the preservation of the pituitary hormonal axis (Pearson Chi-Square P < 0.001). Conclusions: Progressive displacement of the NRPG preoperatively, and lack of restitution of the NRPG on postoperative MRI appeared to correlate with the postoperative pituitary functional loss. PMID:22754732

Functional outcomes of Gartland III supracondylar humerus fractures with early neurovascular complications in children: A retrospective observational study.

PubMed

Wang, Sung Il; Kwon, Tae Young; Hwang, Hong Pil; Kim, Jung Ryul

2017-06-01

This was a retrospective observational study. The aim of this study was to evaluate functional outcomes in children treated for Gartland III supracondylar humerus (SCH) fracture with neurovascular (NV) injuries using validated outcome measures. A secondary goal was to determine whether clinical parameters such as age at injury, sex, weight, fracture site, and/or direction of displacement could predict NV injury at the time of fracture or long-term functional outcomes in these patients.One hundred fifty-four patients of Gartland III SCH fractures between March 2004 and May 2013 were studied retrospectively. The patients were divided into 2 groups according to the presence of NV injury. Medical records and radiographs were reviewed to assess several parameters, including age, sex, weight, treatment intervention, the extremity involved, direction of fracture displacement, and NV injury. Functional outcome was assessed on final follow-up using the Pediatric Outcomes Data Collection Instrument (PODCI) and Quick Disabilities of the Arm, Shoulder, and Hand (Quick DASH) outcome measures. Statistical analysis was used to determine the relationship between NV injury and functional outcomes.There were 33 cases with Gartland III SCH fracture associated with NV injuries (10 cases of vascular compromise, 14 cases of neural injury, and 9 cases involving both vascular compromise and neural injury). There were significant differences between the 2 groups in age (P  =  .048), weight (P  =  .009), and direction of displacement (P  =  .004). Vascular compromise and median nerve injury were most common in fractures with posterolateral displacement, and radial nerve injuries were common in fractures with posteromedial displacement. The mean global function score in the PODCI was 91.4 points, and the mean Quick DASH score was 11.7 points, with excellent functional outcomes. No differences in outcomes were identified based upon age, fracture site, sex, weight, direction of displacement, or operative technique in NV injury patients (P > .05).The majority of patients with Gartland III SCH fractures associated with NV injuries returned to a high functioning level after treatment of their injuries. NV injury does not appear to influence functional outcomes. Good functional results can be expected regardless of age, fracture site, sex, weight, direction of displacement, and operative technique.

Mechanisms of Radiation Induced Effects in Carbon Nanotubes

DTIC Science & Technology

2016-10-01

the defect types created for both ionizing and non-ionizing particles under exposure to high total ionization and displacement damage doses. Carbon...and displacement damage doses. Additionally, the radiation effects on CNT carrier transport parameters (mobility, lifetime, conductivity) have been...thermal oxidation. 2. Radiation Testing of SWCNTs 2.1 Displacement Damage Dose Effects as a Function of SWCNT Electronic-Type Displacement damage does

A study of the displacement of a Wankel rotary engine

NASA Astrophysics Data System (ADS)

Beard, J. E.; Pennock, G. R.

1993-03-01

The volumetric displacement of a Wankel rotary engine is a function of the trochoid ratio and the pin size ratio, assuming the engine has a unit depth and the number of lobes is specified. The mathematical expression which defines the displacement contains a function which can be evaluated directly and a normal elliptic integral of the second type which does not have an explicit solution. This paper focuses on the contribution of the elliptic integral to the total displacement of the engine. The influence of the elliptic integral is shown to account for as much as 20 percent of the total displacement, depending on the trochoid ratio and the pin size ratio. Two numerical integration techniques are compared in the paper, namely, the trapezoidal rule and Simpson's 1/3 rule. The bounds on the error, associated with each numerical method, are analyzed. The results indicate that the numerical method has a minimal effect on the accuracy of the calculated displacement for a practical number of integration steps. The paper also evaluates the influence of manufacturing tolerances on the calculated displacement and the actual displacement. Finally. a numerical example of the common three-lobed Wankel rotary engine is included for illustrative purposes.

Ab initio molecular dynamics simulations of low energy recoil events in MgO

DOE PAGES

Petersen, B. A.; Liu, B.; Weber, W. J.; ...

2017-01-11

In this paper, low-energy recoil events in MgO are studied using ab initio molecular dynamics simulations to reveal the dynamic displacement processes and final defect configurations. Threshold displacement energies, E d, are obtained for Mg and O along three low-index crystallographic directions, [100], [110], and [111]. The minimum values for E d are found along the [110] direction consisting of the same element, either Mg or O atoms. Minimum threshold values of 29.5 eV for Mg and 25.5 eV for O, respectively, are suggested from the calculations. For other directions, the threshold energies are considerably higher, 65.5 and 150.0 eVmore » for O along [111] and [100], and 122.5 eV for Mg along both [111] and [100] directions, respectively. These results show that the recoil events in MgO are partial-charge transfer assisted processes where the charge transfer plays an important role. Finally, there is a similar trend found in other oxide materials, where the threshold displacement energy correlates linearly with the peak partial-charge transfer, suggesting this behavior might be universal in ceramic oxides.« less

Factors influencing the life cycle burdens of the recovery of energy from residual municipal waste.

PubMed

Burnley, Stephen; Coleman, Terry; Peirce, Adam

2015-05-01

A life cycle assessment was carried out to assess a selection of the factors influencing the environmental impacts and benefits of incinerating the fraction of municipal waste remaining after source-separation for reuse, recycling, composting or anaerobic digestion. The factors investigated were the extent of any metal and aggregate recovery from the bottom ash, the thermal efficiency of the process, and the conventional fuel for electricity generation displaced by the power generated. The results demonstrate that incineration has significant advantages over landfill with lower impacts from climate change, resource depletion, acidification, eutrophication human toxicity and aquatic ecotoxicity. To maximise the benefits of energy recovery, metals, particularly aluminium, should be reclaimed from the residual bottom ash and the energy recovery stage of the process should be as efficient as possible. The overall environmental benefits/burdens of energy from waste also strongly depend on the source of the power displaced by the energy from waste, with coal giving the greatest benefits and combined cycle turbines fuelled by natural gas the lowest of those considered. Regardless of the conventional power displaced incineration presents a lower environmental burden than landfill. Copyright © 2015 Elsevier Ltd. All rights reserved.

A new method to simulate the effects of viscous fingering on miscible displacement processes in porous media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vossoughi, S.; Green, D.W.; Smith, J.E.

This paper presents a new method to simulate the effects of viscous fingering on miscible displacement processes in porous media. The method is based on the numerical solution of a general form of the convection-dispersion equation. In this equation the convection term is represented by a fractional flow function. The fractional flow function is derived from Darcy's law using a concentration-dependent, average viscosity and relative flow area to each fluid at any point in the bed. The method was extended to the description of a polymer flood by including retention and inaccessible pore volume. A Langmuir-type model for polymer retentionmore » in the rock was used. The resulting convection-dispersion equation for displacement by polymer was then solved numerically by the use of a finite element method with linear basis functions and Crank-Nicholson derivative approximation. History matches were performed on four sets of laboratory data to verify the model. These were: an unfavorable viscosity ratio displacement, stable displacement of glycerol by polymer solution, unstable displacement of brine by a slug of polymer solution, and a favorable viscosity ratio displacement. In general, computed results from the model matched laboratory data closely. Good agreement of the model with experiments over a significant range of variables lends support to the analysis.« less

Framework for non-coherent interface models at finite displacement jumps and finite strains

NASA Astrophysics Data System (ADS)

Ottosen, Niels Saabye; Ristinmaa, Matti; Mosler, Jörn

2016-05-01

This paper deals with a novel constitutive framework suitable for non-coherent interfaces, such as cracks, undergoing large deformations in a geometrically exact setting. For this type of interface, the displacement field shows a jump across the interface. Within the engineering community, so-called cohesive zone models are frequently applied in order to describe non-coherent interfaces. However, for existing models to comply with the restrictions imposed by (a) thermodynamical consistency (e.g., the second law of thermodynamics), (b) balance equations (in particular, balance of angular momentum) and (c) material frame indifference, these models are essentially fiber models, i.e. models where the traction vector is collinear with the displacement jump. This constraints the ability to model shear and, in addition, anisotropic effects are excluded. A novel, extended constitutive framework which is consistent with the above mentioned fundamental physical principles is elaborated in this paper. In addition to the classical tractions associated with a cohesive zone model, the main idea is to consider additional tractions related to membrane-like forces and out-of-plane shear forces acting within the interface. For zero displacement jump, i.e. coherent interfaces, this framework degenerates to existing formulations presented in the literature. For hyperelasticity, the Helmholtz energy of the proposed novel framework depends on the displacement jump as well as on the tangent vectors of the interface with respect to the current configuration - or equivalently - the Helmholtz energy depends on the displacement jump and the surface deformation gradient. It turns out that by defining the Helmholtz energy in terms of the invariants of these variables, all above-mentioned fundamental physical principles are automatically fulfilled. Extensions of the novel framework necessary for material degradation (damage) and plasticity are also covered.

Compression-after-Impact and Bend Fatigue Results of Glass/Epoxy Composites with Compliant Interlayer and Needling Interlaminar Enhancements

DTIC Science & Technology

2017-05-22

velocity impact of 2-D woven fabric panels displacement response with various interlaminar enhancements ............................... 7 Fig. 3 Low...various interlaminar enhancements ............. 9 Fig. 8 Low-velocity impact displacement response for 3-D TPU interlayer composites...The results for the impact testing of the panels with 2-D woven glass fabrics are provided in Figs. 2–6 for displacement versus time, energy versus

Shear-strain gradient induced polarization reversal in ferroelectric BaTiO3 thin films: A first-principles total-energy study

NASA Astrophysics Data System (ADS)

Li, Guannan; Huang, Xiaokun; Hu, Jingsan; Zhang, Weiyi

2017-04-01

Based on the first-principles total-energy calculation, we have studied the shear-strain gradient effect on the polarization reversal of ferroelectric BaTiO3 thin films. By calculating the energies of double-domain supercells for different electric polarization, shear-strain gradients, and domain-wall displacement, we extracted, in addition to the domain-wall energy, the polarization energy, elastic energy, and flexoelectric coefficient of a single domain. The constructed Landau-Devonshire phenomenological theory yields a critical shear-strain gradient of 9.091 ×107/m (or a curvature radius (R ) of 110 Å) for reversing the 180∘ domain at room temperature, which is on the same order of the experimentally estimated value of 3.333 ×107/m (R =300 Å ). In contrast to the commonly used linear response theory, the flexoelectric coefficient derived from fitting the total energy to a Landau-Devonshire energy functional does not depend on the specific pseudopotential. Thus, our method offers an alternative numerical approach to study the flexoelectric effect.

Inductor-Free Wireless Energy Delivery via Maxwell's Displacement Current from an Electrodeless Triboelectric Nanogenerator.

PubMed

Cao, Xia; Zhang, Meng; Huang, Jinrong; Jiang, Tao; Zou, Jingdian; Wang, Ning; Wang, Zhong Lin

2018-02-01

Wireless power delivery has been a dream technology for applications in medical science, security, radio frequency identification (RFID), and the internet of things, and is usually based on induction coils and/or antenna. Here, a new approach is demonstrated for wireless power delivery by using the Maxwell's displacement current generated by an electrodeless triboelectric nanogenerator (TENG) that directly harvests ambient mechanical energy. A rotary electrodeless TENG is fabricated using the contact and sliding mode with a segmented structure. Due to the leakage of electric field between the segments during relative rotation, the generated Maxwell's displacement current in free space is collected by metal collectors. At a gap distance of 3 cm, the output wireless current density and voltage can reach 7 µA cm -2 and 65 V, respectively. A larger rotary electrodeless TENG and flexible wearable electrodeless TENG are demonstrated to power light-emitting diodes (LEDs) through wireless energy delivery. This innovative discovery opens a new avenue for noncontact, wireless energy transmission for applications in portable and wearable electronics. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Direct charge radioisotope activation and power generation

DOEpatents

Lal, Amit; Li, Hui; Blanchard, James P.; Henderson, Douglass L.

2002-01-01

An activator has a base on which is mounted an elastically deformable micromechanical element that has a section that is free to be displaced toward the base. An absorber of radioactively emitted particles is formed on the base or the displaceable section of the deformable element and a source is formed on the other of the displaceable section or the base facing the absorber across a small gap. The radioactive source emits charged particles such as electrons, resulting in a buildup of charge on the absorber, drawing the absorber and source together and storing mechanical energy as the deformable element is bent. When the force between the absorber and the source is sufficient to bring the absorber into effective electrical contact with the source, discharge of the charge between the source and absorber allows the deformable element to spring back, releasing the mechanical energy stored in the element. An electrical generator such as a piezoelectric transducer may be secured to the deformable element to convert the released mechanical energy to electrical energy that can be used to provide power to electronic circuits.

Nature of the water/aromatic parallel alignment interactions.

PubMed

Mitoraj, Mariusz P; Janjić, Goran V; Medaković, Vesna B; Veljković, Dušan Ž; Michalak, Artur; Zarić, Snežana D; Milčić, Miloš K

2015-01-30

The water/aromatic parallel alignment interactions are interactions where the water molecule or one of its O-H bonds is parallel to the aromatic ring plane. The calculated energies of the interactions are significant, up to ΔE(CCSD)(T)(limit) = -2.45 kcal mol(-1) at large horizontal displacement, out of benzene ring and CH bond region. These interactions are stronger than CH···O water/benzene interactions, but weaker than OH···π interactions. To investigate the nature of water/aromatic parallel alignment interactions, energy decomposition methods, symmetry-adapted perturbation theory, and extended transition state-natural orbitals for chemical valence (NOCV), were used. The calculations have shown that, for the complexes at large horizontal displacements, major contribution to interaction energy comes from electrostatic interactions between monomers, and for the complexes at small horizontal displacements, dispersion interactions are dominant binding force. The NOCV-based analysis has shown that in structures with strong interaction energies charge transfer of the type π → σ*(O-H) between the monomers also exists. © 2014 Wiley Periodicals, Inc.

Applications of Displacement Transfer Functions to Deformed Shape Predictions of the GIII Swept-Wing Structure

NASA Technical Reports Server (NTRS)

Lung, Shun-Fat; Ko, William L.

2016-01-01

The displacement transfer functions (DTFs) were applied to the GIII swept wing for the deformed shape prediction. The calculated deformed shapes are very close to the correlated finite element results as well as the measured data. The convergence study showed that using 17 strain stations, the wing-tip displacement prediction error was 1.6 percent, and that there is no need to use a large number of strain stations for G-III wing shape predictions.

Focal ratio degradation: a new perspective

NASA Astrophysics Data System (ADS)

Haynes, Dionne M.; Withford, Michael J.; Dawes, Judith M.; Haynes, Roger; Bland-Hawthorn, Joss

2008-07-01

We have developed an alternative FRD empirical model for the parallel laser beam technique which can accommodate contributions from both scattering and modal diffusion. It is consistent with scattering inducing a Lorentzian contribution and modal diffusion inducing a Gaussian contribution. The convolution of these two functions produces a Voigt function which is shown to better simulate the observed behavior of the FRD distribution and provides a greatly improved fit over the standard Gaussian fitting approach. The Voigt model can also be used to quantify the amount of energy displaced by FRD, therefore allowing astronomical instrument scientists to identify, quantify and potentially minimize the various sources of FRD, and optimise the fiber and instrument performance.

Halogen, Hydroxy, Mercapto and Amino-Compounds: A Mechanistic Study--2

ERIC Educational Resources Information Center

Hanson, R. W.

1976-01-01

Compare reactions in which the functional groups of title compounds are displaced. The overall order of activity observed for alkyl halides, alcohols, thiels, and aliphatic amines acting as bases or nucleophiles is reversed when reactions involve displacement of the functional group. (MLH)

Displaced clavicle fractures in adolescents: facts, controversies, and current trends.

PubMed

Pandya, Nirav K; Namdari, Surena; Hosalkar, Harish S

2012-08-01

There is an increasing trend toward stabilization and fixation of markedly displaced midshaft clavicle fractures in adolescents. Recent studies in the adult literature have shown a greater prevalence of symptomatic malunion, nonunion, and poor functional outcomes after nonsurgical management of displaced fractures. Fixation of displaced midshaft clavicle fractures can restore length and alignment, resulting in shorter time to union. Symptomatic malunion after significantly displaced fractures in adolescents may be more common than previously thought. Adolescents often have high functional demands, and their remodeling potential is limited. Knowledge of bone biology and the effects of shortening, angulation, and rotation on shoulder girdle mechanics is critical in decision making in order to increase the likelihood of optimal results at skeletal maturity. Selection of fixation is dependent on many factors, including fracture type, patient age, skeletal maturity, and surgeon comfort.

Field theoretic approach to roughness corrections

NASA Astrophysics Data System (ADS)

Wu, Hua Yao; Schaden, Martin

2012-02-01

We develop a systematic field theoretic description of roughness corrections to the Casimir free energy of a massless scalar field in the presence of parallel plates with mean separation a. Roughness is modeled by specifying a generating functional for correlation functions of the height profile. The two-point correlation function being characterized by its variance, σ2, and correlation length, ℓ. We obtain the partition function of a massless scalar quantum field interacting with the height profile of the surface via a δ-function potential. The partition function is given by a holographic reduction of this model to three coupled scalar fields on a two-dimensional plane. The original three-dimensional space with a flat parallel plate at a distance a from the rough plate is encoded in the nonlocal propagators of the surface fields on its boundary. Feynman rules for this equivalent 2+1-dimensional model are derived and its counterterms constructed. The two-loop contribution to the free energy of this model gives the leading roughness correction. The effective separation, aeff, to a rough plate is measured to a plane that is displaced a distance ρ∝σ2/ℓ from the mean of its profile. This definition of the separation eliminates corrections to the free energy of order 1/a4 and results in unitary scattering matrices. We obtain an effective low-energy model in the limit ℓ≪a. It determines the scattering matrix and equivalent planar scattering surface of a very rough plate in terms of the single length scale ρ. The Casimir force on a rough plate is found to always weaken with decreasing correlation length ℓ. The two-loop approximation to the free energy interpolates between the free energy of the effective low-energy model and that of the proximity force approximation - the force on a very rough plate with σ≳0.5ℓ being weaker than on a planar Dirichlet surface at any separation.

Estimating Renewable Energy Economic Potential in the United States: Methodology and Initial Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, Austin; Beiter, Philipp; Heimiller, Donna

The report describes a geospatial analysis method to estimate the economic potential of several renewable resources available for electricity generation in the United States. Economic potential, one measure of renewable generation potential, is defined in this report as the subset of the available resource technical potential where the cost required to generate the electricity (which determines the minimum revenue requirements for development of the resource) is below the revenue available in terms of displaced energy and displaced capacity.

Displacement energy of the surface layers of tungsten

NASA Astrophysics Data System (ADS)

Han, Longtao; Krstic, Predrag

2015-11-01

A molecular dynamics study with BOP potential is used to calculate the threshold displacement energy (ED) of primary knock-on atoms in the surface layers of the tungsten bcc crystal lattice at 300 K and at various crystallographic directions. Depending on the direction, ED is 10% to 75% smaller from the bulk value at the first layer, interfacing vacuum, while it reaches close to the bulk value already at the third tungsten layer. Supported by IACS of SBU and LDRD of PPPL.

Study of the Structural Stability in Intermetallics Using Displacive Transformation Paths

NASA Astrophysics Data System (ADS)

Sob, M.; Wang, L. G.; Vitek, V.

1997-03-01

Relative structural stability of TiAl, FeAl, NiAl and NiTi is studied by investigating displacive phase transformation paths. These include the well known tetragonal (Bain's) and trigonal deformation paths which correspond to large homogeneous straining, and also more complex paths that include the shuffling of atomic planes. The results of full-potential APW total energy calculations show that all higher-energy cubic structures studied are locally unstable with respect to some deformation modes. There may or may not be symmetry-dictated energy extrema corresponding to cubic lattices depending on the atomic ordering. However, other energy extrema that are not imposed by symmetry requirements occur along the transformation paths. Configurations corresponding to energy minima may represent metastable structures that can play an important role in interfaces and other extended defects.

Integrating CO₂ storage with geothermal resources for dispatchable renewable electricity

DOE PAGES

Buscheck, Thomas A.; Bielicki, Jeffrey M.; Chen, Mingjie; ...

2014-12-31

We present an approach that uses the huge fluid and thermal storage capacity of the subsurface, together with geologic CO₂ storage, to harvest, store, and dispatch energy from subsurface (geothermal) and surface (solar, nuclear, fossil) thermal resources, as well as energy from electrical grids. Captured CO₂ is injected into saline aquifers to store pressure, generate artesian flow of brine, and provide an additional working fluid for efficient heat extraction and power conversion. Concentric rings of injection and production wells are used to create a hydraulic divide to store pressure, CO₂, and thermal energy. Such storage can take excess power frommore » the grid and excess/waste thermal energy, and dispatch that energy when it is demanded, enabling increased penetration of variable renewables. Stored CO₂ functions as a cushion gas to provide enormous pressure-storage capacity and displaces large quantities of brine, which can be desalinated and/or treated for a variety of beneficial uses.« less

A new method to simulate the effects of viscous fingering on miscible displacement processes in porous media

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vossoughi, S.; Green, D.W.; Smith, J.E.

Dispersion and viscous fingering are important parameters in miscible displacement. Effects of dispersion on concentration profiles in porous media can be simulated when the viscosity ratio is favorable. The capability to simulate viscous fingering is limited. This paper presents a new method to simulate effects of viscous fingering on miscible displacement processes in porous media. The method is based on the numerical solution of a general form of the convection-dispersion equation. In this equation the convection term is represented by a fractional flow function. The fractional flow function is derived from Darcy's law by using a concentration-dependent average viscosity andmore » relative flow area to each fluid at any point in the bed. The method was extended to the description of a polymer flood by including retention and inaccessible PV. A Langmuir-type model for polymer retention in the rock was used. The resulting convection-dispersion equation for displacement by polymer was solved numerically by the use of a finite-element method with linear basis functions and Crank-Nicholson derivative approximation. History matches were performed on four sets of laboratory data to verify the model: (1) an unfavorable viscosity ratio displacement, (2) stable displacement of glycerol by polymer solution, (3) unstable displacement of brine by a slug of polymer solution, and (4) a favorable viscosity ratio displacement. In general, computed results from the model matched laboratory data closely. Good agreement of the model with experiments over a significant range of variables lends support to the analysis.« less

Energy Dissipation of Rayleigh Waves due to Absorption Along the Path by the Use of Finite Element Method

DTIC Science & Technology

1979-07-31

3 x 3 t Strain vector a ij,j Space derivative of the stress tensor Fi Force vector per unit volume o Density x CHAPTER III F Total force K Stiffness...matrix 6Vector displacements M Mass matrix B Space operating matrix DO Matrix moduli 2 x 3 DZ Operating matrix in Z direction N Matrix of shape...dissipating medium the deformation of a solid is a function of time, temperature and space . Creep phenomenon is a deformation process in which there is

First-Principles Studies of Pentaerythritol Tetranitrate (PETN) Single Crystal Unit Cell Volumes and Vibrational Frequencies under Hydrostatic Pressure

NASA Astrophysics Data System (ADS)

Perger, Warren F.; Zhao, Jijun; Winey, J. M.; Gupta, Y. M.

2006-07-01

The vibrational frequencies of the PETN molecular crystal were calculated using the first-principles CRYSTAL03 program which employs an all-electron LCAO approach and calculates analytic first derivatives of the total energy with respect to atomic displacements. Numerical second derivatives were used to enable calculation of the vibrational frequencies at ambient pressure and under various states of compression. Three different density functionals, B3LYP, PW91, and X3LYP were used to examine the effect of the exchange-correlation functional on the vibrational frequencies. The average deviation with experimental results is shown to be on the order of 2-3%, depending on the functional used. The pressure-induced shift of the vibrational frequencies is presented.

Anatomically precontoured LCP for delayed union of a medial third clavicle fracture. Case report with review of the literature.

PubMed

Siebenlist, S; Sandmann, G; Kirchhoff, C; Biberthaler, P; Neumaier, M

2013-01-01

Fractures of the medial clavicle third are rare injuries. Even in case of significant fracture displacement, their therapeutic management has been nonoperative. Recently, surgical intervention has become mandatory for displaced fractures types to prevent non-union and functional complaints, but the optimal operative strategy is being discussed controversially. We describe the case of a 63-year-old male patient with a significantly displaced medial clavicle fracture after failed conservative treatment resulting in restricted, painful shoulder function. The patient underwent open reduction and osteosynthesis with an anatomically precontoured locking compression plate (LCP). One year after surgery the patient is free of complaints and has returned to his preinjury activity level without any functional restrictions. As a not yet reported operative approach, anatomically preshaped locking plating seems to be an effective fixation method for displaced fractures of the medial clavicle third. The operative management is described in detail and discussed with the current literature. Based on the presented case, we underline the statement that displaced medial clavicle fractures should be surgically addressed to avoid late damage.

On the Modeling of Shells in Multibody Dynamics

NASA Technical Reports Server (NTRS)

Bauchau, Olivier A.; Choi, Jou-Young; Bottasso, Carlo L.

2000-01-01

Energy preserving/decaying schemes are presented for the simulation of the nonlinear multibody systems involving shell components. The proposed schemes are designed to meet four specific requirements: unconditional nonlinear stability of the scheme, a rigorous treatment of both geometric and material nonlinearities, exact satisfaction of the constraints, and the presence of high frequency numerical dissipation. The kinematic nonlinearities associated with arbitrarily large displacements and rotations of shells are treated in a rigorous manner, and the material nonlinearities can be handled when the, constitutive laws stem from the existence of a strain energy density function. The efficiency and robustness of the proposed approach is illustrated with specific numerical examples that also demonstrate the need for integration schemes possessing high frequency numerical dissipation.

Phonon and thermodynamical properties of CuSc: A DFT study

NASA Astrophysics Data System (ADS)

Jain, Ekta; Pagare, Gitanjali; Dubey, Shubha; Sanyal, S. P.

2018-05-01

A detailed systematic theoretical investigation of phonon and thermodynamical behavior of CuSc intermetallic compound has been carried out by uing first-principles density functional theory in B2-type (CsCl) crystal structure. Phonon dispersion curve and phonon density of states (PhDOS) are studied which confirm the stability of CuSc intermetallic compound in B2 phase. It is found that PhDOS at high frequencies mostly composed of Sc states. We have also presented some temperature dependent properties such as entropy, free energy, heat capacity, internal energy and thermal displacement, which are computed under PHONON code. The various features of these quantities are discussed in detail. From these results we demonstrate that the particular intermetallic have better ductility and larger thermal expansion.

Constraints on geothermal reservoir volume change calculations from InSAR surface displacements and injection and production data

NASA Astrophysics Data System (ADS)

Kaven, J. Ole; Barbour, Andrew J.; Ali, Tabrez

2017-04-01

Continual production of geothermal energy at times leads to significant surface displacement that can be observed in high spatial resolution using InSAR imagery. The surface displacement can be analyzed to resolve volume change within the reservoir revealing the often-complicated patterns of reservoir deformation. Simple point source models of reservoir deformation in a homogeneous elastic or poro-elastic medium can be superimposed to provide spatially varying, kinematic representations of reservoir deformation. In many cases, injection and production data are known in insufficient detail; but, when these are available, the same Green functions can be used to constrain the reservoir deformation. Here we outline how the injection and production data can be used to constrain bounds on the solution by posing the inversion as a quadratic programming with inequality constraints and regularization rather than a conventional least squares solution with regularization. We apply this method to InSAR-derived surface displacements at the Coso and Salton Sea Geothermal Fields in California, using publically available injection and production data. At both geothermal fields the available surface deformation in conjunction with the injection and production data permit robust solutions for the spatially varying reservoir deformation. The reservoir deformation pattern resulting from the constrained quadratic programming solution is more heterogeneous when compared to a conventional least squares solution. The increased heterogeneity is consistent with the known structural controls on heat and fluid transport in each geothermal reservoir.

Comparing primary energy attributed to renewable energy with primary energy equivalent to determine carbon abatement in a national context.

PubMed

Gallachóir, Brian P O; O'Leary, Fergal; Bazilian, Morgan; Howley, Martin; McKeogh, Eamon J

2006-01-01

The current conventional approach to determining the primary energy associated with non-combustible renewable energy (RE) sources such as wind energy and hydro power is to equate the electricity generated from these sources with the primary energy supply. This paper compares this with an approach that was formerly used by the IEA, in which the primary energy equivalent attributed to renewable energy was equated with the fossil fuel energy it displaces. Difficulties with implementing this approach in a meaningful way for international comparisons lead to most international organisations abandoning the primary energy equivalent methodology. It has recently re-emerged in prominence however, as efforts grow to develop baseline procedures for quantifying the greenhouse gas (GHG) emissions avoided by renewable energy within the context of the Kyoto Protocol credit trading mechanisms. This paper discusses the primary energy equivalent approach and in particular the distinctions between displacing fossil fuel energy in existing plant or in new plant. The approach is then extended provide insight into future primary energy displacement by renewable energy and to quantify the amount of CO2 emissions avoided by renewable energy. The usefulness of this approach in quantifying the benefits of renewable energy is also discussed in an energy policy context, with regard to increasing security of energy supply as well as reducing energy-related GHG (and other) emissions. The approach is applied in a national context and Ireland is case study country selected for this research. The choice of Ireland is interesting in two respects. The first relates to the high proportion of electricity only fossil fuel plants in Ireland resulting in a significant variation between primary energy and primary energy equivalent. The second concerns Ireland's poor performance to date in limiting GHG emissions in line with its Kyoto target and points to the need for techniques to quantify the potential contribution of renewable energy in achieving the target set.

Solar energy receiver for a Stirling engine

NASA Technical Reports Server (NTRS)

Selcuk, M. K. (Inventor)

1980-01-01

A solar energy receiver includes a separable endless wall formed of a ceramic material in which a cavity of substantially cylindrical configuration is defined for entrapping solar flux. An acceptance aperture is adapted to admit to the cavity a concentrated beam of solar energy. The wall is characterized by at least one pair of contiguously related segments separated by lines of cleavage intercepting the aperture. At least one of the segments is supported for pivotal displacement. A thermal-responsive actuator is adapted to respond to excessive temperatures within the cavity for initiating pivoted displacement of one segment, whereby thermal flux is permitted to escape from the cavity.

Experimental investigation of the displacement dynamics during biphasic flow in porous media

NASA Astrophysics Data System (ADS)

Ayaz, Monem; Toussaint, Renaud; Måløy, Knut-Jørgen; Schafer, Gerhard

2016-04-01

We experimentally study the interface dynamics of an immiscible fluid as it displaces a fully saturated porous medium. The system is confined by a vertically oriented Hele-Shaw cell, with piezoelectric type acoustic sensors mounted along the centerline. During drainage potential surface energy is stored at the interface up to a given threshold in pressure, at which an instability occurs as new pores are invaded and the radius of curvature of the interface increases locally, the energy gets released, and part of this energy is detectable as acoustic emission. By detecting pore-scale events emanating from the interface at various points, we look to develop techniques for localizing the displacement front. To assess the quality, optical monitoring is done using a high speed camera.In our study we also aim to gain further insight into the interface dynamics by varying parameters such as the effective gravity, and the invasion speed and using other methods of probing the system such as active tomography. We here present our preliminary results of this study.

Regional variations in the health, environmental, and climate benefits of wind and solar generation

PubMed Central

Siler-Evans, Kyle; Azevedo, Inês Lima; Morgan, M. Granger; Apt, Jay

2013-01-01

When wind or solar energy displace conventional generation, the reduction in emissions varies dramatically across the United States. Although the Southwest has the greatest solar resource, a solar panel in New Jersey displaces significantly more sulfur dioxide, nitrogen oxides, and particulate matter than a panel in Arizona, resulting in 15 times more health and environmental benefits. A wind turbine in West Virginia displaces twice as much carbon dioxide as the same turbine in California. Depending on location, we estimate that the combined health, environmental, and climate benefits from wind or solar range from $10/MWh to $100/MWh, and the sites with the highest energy output do not yield the greatest social benefits in many cases. We estimate that the social benefits from existing wind farms are roughly 60% higher than the cost of the Production Tax Credit, an important federal subsidy for wind energy. However, that same investment could achieve greater health, environmental, and climate benefits if it were differentiated by region. PMID:23798431

Regional variations in the health, environmental, and climate benefits of wind and solar generation.

PubMed

Siler-Evans, Kyle; Azevedo, Inês Lima; Morgan, M Granger; Apt, Jay

2013-07-16

When wind or solar energy displace conventional generation, the reduction in emissions varies dramatically across the United States. Although the Southwest has the greatest solar resource, a solar panel in New Jersey displaces significantly more sulfur dioxide, nitrogen oxides, and particulate matter than a panel in Arizona, resulting in 15 times more health and environmental benefits. A wind turbine in West Virginia displaces twice as much carbon dioxide as the same turbine in California. Depending on location, we estimate that the combined health, environmental, and climate benefits from wind or solar range from $10/MWh to $100/MWh, and the sites with the highest energy output do not yield the greatest social benefits in many cases. We estimate that the social benefits from existing wind farms are roughly 60% higher than the cost of the Production Tax Credit, an important federal subsidy for wind energy. However, that same investment could achieve greater health, environmental, and climate benefits if it were differentiated by region.

Sustainable biofuel contributions to carbon mitigation and energy independence

DOE PAGES

Lippke, Bruce; Gustafson, Richard; Venditti, Richard; ...

2011-10-19

The growing interest in US biofuels has been motivated by two primary national policy goals, (1) to reduce carbon emissions and (2) to achieve energy independence. However, the current low cost of fossil fuels is a key barrier to investments in woody biofuel production capacity. The effectiveness of wood derived biofuels must consider not only the feedstock competition with low cost fossil fuels but also the wide range of wood products uses that displace different fossil intensive products. Alternative uses of wood result in substantially different unit processes and carbon impacts over product life cycles. We developed life cycle datamore » for new bioprocessing and feedstock collection models in order to make life cycle comparisons of effectiveness when biofuels displace gasoline and wood products displace fossil intensive building materials. Wood products and biofuels can be joint products from the same forestland. Furthermore, substantial differences in effectiveness measures are revealed as well as difficulties in valuing tradeoffs between carbon mitigation and energy independence.« less

Resistance of Concrete Masonry Walls With Membrane Catcher Systems Subjected to Blast Loading

DTIC Science & Technology

2010-12-01

fiber reinforcement) sprayed-on polymers. The early versions of this approach were a polyurea -based coating similar to that used for truck bed liners...displacement. Figure 5 illustrates a resistance function using a polyurea membrane retrofit, and Figure 6 shows the complete resistance function. The...resistance function is truncated for these conditions: Figure 5. Resistance function — 3 mm thick polyurea retrofit DIsplacement (mm) P re s s u re

Responsive materials: A novel design for enhanced machine-augmented composites

PubMed Central

Bafekrpour, Ehsan; Molotnikov, Andrey; Weaver, James C.; Brechet, Yves; Estrin, Yuri

2014-01-01

The concept of novel responsive materials with a displacement conversion capability was further developed through the design of new machine-augmented composites (MACs). Embedded converter machines and MACs with improved geometry were designed and fabricated by multi-material 3D printing. This technique proved to be very effective in fabricating these novel composites with tuneable elastic moduli of the matrix and the embedded machines and excellent bonding between them. Substantial improvement in the displacement conversion efficiency of the new MACs over the existing ones was demonstrated. Also, the new design trebled the energy absorption of the MACs. Applications in energy absorbers as well as mechanical sensors and actuators are thus envisaged. A further type of MACs with conversion ability, viz. conversion of compressive displacements to torsional ones, was also proposed. PMID:24445490

Neuropsychological functioning in posttraumatic stress disorder following forced displacement in older adults and their offspring.

PubMed

Jelinek, Lena; Wittekind, Charlotte E; Moritz, Steffen; Kellner, Michael; Muhtz, Christoph

2013-12-15

The aim of the present study was to investigate neuropsychological performance in an untried trauma sample of older adults displaced during childhood at the end of World War II (WWII) with and without posttraumatic stress disorder (PTSD) as well as transgenerational effects of trauma and PTSD on their offspring. Displaced older adults with (n=20) and without PTSD (n=24) and nondisplaced healthy individuals (n=11) as well as one of their respective offspring were assessed with a large battery of cognitive tests (primarily targeting memory functioning). No evidence for deficits in neuropsychological performance was found in the aging group of displaced people with PTSD. Moreover, no group difference emerged in the offspring groups. Findings may be interpreted as first evidence for a rather resilient PTSD group of older adults that is available for assessment 60 years after displacement. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Differential dpa calculations with SPECTRA-PKA

NASA Astrophysics Data System (ADS)

Gilbert, M. R.; Sublet, J.-Ch.

2018-06-01

The processing code SPECTRA-PKA produces energy spectra of primary atomic recoil events (or primary knock-on atoms, PKAs) for any material composition exposed to an irradiation spectrum. Such evaluations are vital inputs for simulations aimed at understanding the evolution of damage in irradiated material, which is generated in cascade displacement events initiated by PKAs. These PKA spectra present the full complexity of the input (to SPECTRA-PKA) nuclear data-library evaluations of recoil events. However, the commonly used displacements per atom (dpa) measure, which is an integral measure over all possible recoil events of the displacement damage dose, is still widely used and has many useful applications - as both a comparative and correlative quantity. This paper describes the methodology employed that allows the SPECTRA-PKA code to evaluate dpa rates using the energy-dependent recoil (PKA) cross section data used for the PKA distributions. This avoids the need for integral displacement kerma cross sections and also provides new insight into the relative importance of different reaction channels (and associated different daughter residual and emitted particles) to the total integrated dpa damage dose. Results are presented for Fe, Ni, W, and SS316. Fusion dpa rates are compared to those in fission, highlighting the increased contribution to damage creation in the former from high-energy threshold reactions.

Driving force and nucleophilicity in SN2 displacements

PubMed Central

Streitwieser, Andrew

1985-01-01

The free energies of activation for reaction of six anionic nucleophiles with methyl iodide in dimethylformamide correlate linearly with the overall heats of reaction in the gas phase. The result indicates that nucleophilicity in this SN2 displacement reaction is dominated by electron affinity and bond-strength effects. PMID:16593634

Comparison of two fractal interpolation methods

NASA Astrophysics Data System (ADS)

Fu, Yang; Zheng, Zeyu; Xiao, Rui; Shi, Haibo

2017-03-01

As a tool for studying complex shapes and structures in nature, fractal theory plays a critical role in revealing the organizational structure of the complex phenomenon. Numerous fractal interpolation methods have been proposed over the past few decades, but they differ substantially in the form features and statistical properties. In this study, we simulated one- and two-dimensional fractal surfaces by using the midpoint displacement method and the Weierstrass-Mandelbrot fractal function method, and observed great differences between the two methods in the statistical characteristics and autocorrelation features. From the aspect of form features, the simulations of the midpoint displacement method showed a relatively flat surface which appears to have peaks with different height as the fractal dimension increases. While the simulations of the Weierstrass-Mandelbrot fractal function method showed a rough surface which appears to have dense and highly similar peaks as the fractal dimension increases. From the aspect of statistical properties, the peak heights from the Weierstrass-Mandelbrot simulations are greater than those of the middle point displacement method with the same fractal dimension, and the variances are approximately two times larger. When the fractal dimension equals to 1.2, 1.4, 1.6, and 1.8, the skewness is positive with the midpoint displacement method and the peaks are all convex, but for the Weierstrass-Mandelbrot fractal function method the skewness is both positive and negative with values fluctuating in the vicinity of zero. The kurtosis is less than one with the midpoint displacement method, and generally less than that of the Weierstrass-Mandelbrot fractal function method. The autocorrelation analysis indicated that the simulation of the midpoint displacement method is not periodic with prominent randomness, which is suitable for simulating aperiodic surface. While the simulation of the Weierstrass-Mandelbrot fractal function method has strong periodicity, which is suitable for simulating periodic surface.

Atomistic modeling and experimental studies of radiation damage in monazite-type LaPO4 ceramics

NASA Astrophysics Data System (ADS)

Ji, Yaqi; Kowalski, Piotr M.; Neumeier, Stefan; Deissmann, Guido; Kulriya, Pawan K.; Gale, Julian D.

2017-02-01

We simulated the threshold displacement energies (Ed), the related displacement and defect formation probabilities, and the energy barriers in LaPO4 monazite-type ceramics. The obtained Ed values for La, P, O primary knock-on atoms (PKA) are 56 eV, 75 eV and 8 eV, respectively. We found that these energies can be correlated with the energy barriers that separate the defect from the initial states. The Ed values are about twice the values of energy barriers, which is explained through an efficient dissipation of the PKA kinetic energy in the considered system. The computed Ed were used in simulations of the extent of radiation damage in La0.2Gd0.8PO4 solid solution, investigated experimentally. We found that this lanthanide phosphate fully amorphises in the ion beam experiments for fluences higher than ∼1013 ions/cm2.

Charge Compensation and Electrostatic Transferability in Three Entropy Stabilized Oxides: Results from Density Functional Theory Calculations

DTIC Science & Technology

2016-09-06

displacements from ideal lattice sites, along with reduction of a few Co and Ni cations. Addition of Li to J14 reduces the lattice constant, consistent...associated with the atoms as well as in displacements of atoms from their ideal lattice sites. II. SYNTHESIS OF THE J141Sc COMPOSITION Berardan et al...Plotted in Figure 6 are the average atom displacements for the three large systems as a function of element type. For J14 (open bars), the dis

Optically phase-locked electronic speckle pattern interferometer system performance for vibration measurement in random displacement fields

NASA Astrophysics Data System (ADS)

Moran, Steve E.; Lugannani, Robert; Craig, Peter N.; Law, Robert L.

1989-02-01

An analysis is made of the performance of an optically phase-locked electronic speckle pattern interferometer in the presence of random noise displacements. Expressions for the phase-locked speckle contrast for single-frame imagery and the composite rms exposure for two sequentially subtracted frames are obtained in terms of the phase-locked composite and single-frame fringe functions. The noise fringe functions are evaluated for stationary, coherence-separable noise displacements obeying Gauss-Markov temporal statistics. The theoretical findings presented here are qualitatively supported by experimental results.

Calculation of Cardiac Kinetic Energy Index from PET images.

PubMed

Sims, John; Oliveira, Marco Antônio; Meneghetti, José Claudio; Gutierrez, Marco Antônio

2015-01-01

Cardiac function can be assessed from displacement measurements in imaging modalities from nuclear medicine Using positron emission tomography (PET) image sequences with Rubidium-82, we propose and estimate the total Kinetic Energy Index (KEf) obtained from the velocity field, which was calculated using 3D optical flow(OF) methods applied over the temporal image sequence. However, it was found that the brightness of the image varied unexpectedly between frames, violating the constant brightness assumption of the OF method and causing large errors in estimating the velocity field. Therefore total brightness was equalized across image frames and the adjusted configuration tested with rest perfusion images acquired from individuals with normal (n=30) and low (n=33) cardiac function. For these images KEf was calculated as 0.5731±0.0899 and 0.3812±0.1146 for individuals with normal and low cardiac function respectively. The ability of KEf to properly classify patients into the two groups was tested with a ROC analysis, with area under the curve estimated as 0.906. To our knowledge this is the first time that KEf has been applied to PET images.

Experimental compliance calibration of the compact fracture toughness specimen

NASA Technical Reports Server (NTRS)

Fisher, D. M.; Buzzard, R. J.

1980-01-01

Compliances and stress intensity coefficients were determined over crack length to width ratios from 0.1 to 0.8. Displacements were measured at the load points, load line, and crack mouth. Special fixturing was devised to permit accurate measurement of load point displacement. The results are in agreement with the currently used results of boundary collocation analyses. The errors which occur in stress intensity coefficients or specimen energy input determinations made from load line displacement measurements rather than from load point measurements are emphasized.

Monte Carlo Techniques for Calculations of Charge Deposition and Displacement Damage from Protons in Visible and Infrared Sensor Arrays

NASA Technical Reports Server (NTRS)

Marshall, Paul; Reed, Robert; Fodness, Bryan; Jordan, Tom; Pickel, Jim; Xapsos, Michael; Burke, Ed

2004-01-01

This slide presentation examines motivation for Monte Carlo methods, charge deposition in sensor arrays, displacement damage calculations, and future work. The discussion of charge deposition sensor arrays includes Si active pixel sensor APS arrays and LWIR HgCdTe FPAs. The discussion of displacement damage calculations includes nonionizing energy loss (NIEL), HgCdTe NIEL calculation results including variance, and implications for damage in HgCdTe detector arrays.

On Displacement Height, from Classical to Practical Formulation: Stress, Turbulent Transport and Vorticity Considerations

NASA Astrophysics Data System (ADS)

Sogachev, Andrey; Kelly, Mark

2016-03-01

Displacement height ( d) is an important parameter in the simple modelling of wind speed and vertical fluxes above vegetative canopies, such as forests. Here we show that, aside from implicit definition through a (displaced) logarithmic profile, accepted formulations for d do not consistently predict flow properties above a forest. Turbulent transport can affect the displacement height, and is an integral part of what is called the roughness sublayer. We develop a more general approach for estimation of d, through production of turbulent kinetic energy and turbulent transport, and show how previous stress-based formulations for displacement height can be seen as simplified cases of a more general definition including turbulent transport. Further, we also give a simplified and practical form for d that is in agreement with the general approach, exploiting the concept of vortex thickness scale from mixing-layer theory. We assess the new and previous displacement height formulations by using flow statistics derived from the atmospheric boundary-layer Reynolds-averaged Navier-Stokes model SCADIS as well as from wind-tunnel observations, for different vegetation types and flow regimes in neutral conditions. The new formulations tend to produce smaller d than stress-based forms, falling closer to the classic logarithmically-defined displacement height. The new, more generally defined, displacement height appears to be more compatible with profiles of components of the turbulent kinetic energy budget, accounting for the combined effects of turbulent transport and shear production. The Coriolis force also plays a role, introducing wind-speed dependence into the behaviour of the roughness sublayer; this affects the turbulent transport, shear production, stress, and wind speed, as well as the displacement height, depending on the character of the forest. We further show how our practical (`mixing-layer') form for d matches the new turbulence-based relation, as well as correspondence to previous (stress-based) formulations.

Molecular dynamics simulations of shock waves in oriented nitromethane single crystals.

PubMed

He, Lan; Sewell, Thomas D; Thompson, Donald L

2011-03-28

The structural relaxation of crystalline nitromethane initially at T = 200 K subjected to moderate (~15 GPa) supported shocks on the (100), (010), and (001) crystal planes has been studied using microcanonical molecular dynamics with the nonreactive Sorescu-Rice-Thompson force field [D. C. Sorescu, B. M. Rice, and D. L. Thompson, J. Phys. Chem. B 104, 8406 (2000)]. The responses to the shocks were determined by monitoring the mass density, the intermolecular, intramolecular, and total temperatures (average kinetic energies), the partitioning of total kinetic energy among Cartesian directions, the radial distribution functions for directions perpendicular to those of shock propagation, the mean-square displacements in directions perpendicular to those of shock propagation, and the time dependence of molecular rotational relaxation as a function of time. The results show that the mechanical response of crystalline nitromethane strongly depends on the orientation of the shock wave. Shocks propagating along [100] and [001] result in translational disordering in some crystal planes but not in others, a phenomenon that we refer to as plane-specific disordering; whereas for [010] the shock-induced stresses are relieved by a complicated structural rearrangement that leads to a paracrystalline structure. The plane-specific translational disordering is more complete by the end of the simulations (~6 ps) for shock propagation along [001] than along [100]. Transient excitation of the intermolecular degrees of freedom occurs in the immediate vicinity of the shock front for all three orientations; the effect is most pronounced for the [010] shock. In all three cases excitation of molecular vibrations occurs more slowly than the intermolecular excitation. The intermolecular and intramolecular temperatures are nearly equal by the end of the simulations, with 400-500 K of net shock heating. Results for two-dimensional mean-square molecular center-of-mass displacements, calculated as a function of time since shock wave passage in planes perpendicular to the direction of shock propagation, show that the molecular translational mobility in the picoseconds following shock wave passage is greatest for [001] and least for the [010] case. In all cases the root-mean-square center-of-mass displacement is small compared to the molecular diameter of nitromethane on the time scale of the simulations. The calculated time scales for the approach to thermal equilibrium are generally consistent with the predictions of a recent theoretical analysis due to Hooper [J. Chem. Phys. 132, 014507 (2010)].

Systematic study of anharmonic features in a principal component analysis of gramicidin A.

PubMed

Kurylowicz, Martin; Yu, Ching-Hsing; Pomès, Régis

2010-02-03

We use principal component analysis (PCA) to detect functionally interesting collective motions in molecular-dynamics simulations of membrane-bound gramicidin A. We examine the statistical and structural properties of all PCA eigenvectors and eigenvalues for the backbone and side-chain atoms. All eigenvalue spectra show two distinct power-law scaling regimes, quantitatively separating large from small covariance motions. Time trajectories of the largest PCs converge to Gaussian distributions at long timescales, but groups of small-covariance PCs, which are usually ignored as noise, have subdiffusive distributions. These non-Gaussian distributions imply anharmonic motions on the free-energy surface. We characterize the anharmonic components of motion by analyzing the mean-square displacement for all PCs. The subdiffusive components reveal picosecond-scale oscillations in the mean-square displacement at frequencies consistent with infrared measurements. In this regime, the slowest backbone mode exhibits tilting of the peptide planes, which allows carbonyl oxygen atoms to provide surrogate solvation for water and cation transport in the channel lumen. Higher-frequency modes are also apparent, and we describe their vibrational spectra. Our findings expand the utility of PCA for quantifying the essential features of motion on the anharmonic free-energy surface made accessible by atomistic molecular-dynamics simulations. Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Crashworthiness characteristics of a carbon fiber reinforced dual-phase epoxy–polyurea hybrid matrix composite

DOE PAGES

Zhou, Hongyu; Attard, Thomas L.; Dhiradhamvit, Kittinan; ...

2014-11-07

In this paper, the crashworthiness characteristics of rectangular tubes made from a Carbon-fiber reinforced Hybrid-Polymeric Matrix (CHMC) composite were investigated using quasi-static and impact crush tests. The hybrid matrix formulation of the CHMC was created by combining an epoxy-based thermosetting polymer with a lightly crosslinked polyurea elastomer at various cure-time intervals and volumetric ratios. The load–displacement responses of both CHMC and carbon-fiber reinforced epoxy (CF/epoxy) specimens were obtained under various crushing speeds; and crashworthiness parameters, such as the average crushing force and specific energy absorption (SEA), were calculated using subsequent load–displacement relationships. The CHMC maintained a high level of structuralmore » integrity and post-crush performance, relative to traditional CF/epoxy. The influence of the curing time and volumetric ratios of the polyurea/epoxy dual-hybridized matrix system on the crashworthiness parameters was also investigated. The results reveal that the load carrying capacity and total energy absorption tend to increase with greater polyurea thickness and lower elapsed reaction curing time of the epoxy although this is typically a function of the loading rate. In conclusion, the mechanism by which the CHMC provides increased damage tolerance was also investigated using scanning electron microscopy (SEM).« less

The use of displacement damage dose to correlate degradation in solar cells exposed to different radiations

NASA Technical Reports Server (NTRS)

Summers, Geoffrey P.; Burke, Edward A.; Shapiro, Philip; Statler, Richard; Messenger, Scott R.; Walters, Robert J.

1994-01-01

It has been found useful in the past to use the concept of 'equivalent fluence' to compare the radiation response of different solar cell technologies. Results are usually given in terms of an equivalent 1 MeV electron or an equivalent 10 MeV proton fluence. To specify cell response in a complex space-radiation environment in terms of an equivalent fluence, it is necessary to measure damage coefficients for a number of representative electron and proton energies. However, at the last Photovoltaic Specialist Conference we showed that nonionizing energy loss (NIEL) could be used to correlate damage coefficients for protons, using measurements for GaAs as an example. This correlation means that damage coefficients for all proton energies except near threshold can be predicted from a measurement made at one particular energy. NIEL is the exact equivalent for displacement damage of linear energy transfer (LET) for ionization energy loss. The use of NIEL in this way leads naturally to the concept of 10 MeV equivalent proton fluence. The situation for electron damage is more complex, however. It is shown that the concept of 'displacement damage dose' gives a more general way of unifying damage coefficients. It follows that 1 MeV electron equivalent fluence is a special case of a more general quantity for unifying electron damage coefficients which we call the 'effective 1 MeV electron equivalent dose'.

Modelling toehold-mediated RNA strand displacement.

PubMed

Šulc, Petr; Ouldridge, Thomas E; Romano, Flavio; Doye, Jonathan P K; Louis, Ard A

2015-03-10

We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5' end of the substrate; and that the displacement slows down with increasing temperature for longer toeholds. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Displacement cascades and defects annealing in tungsten, Part I: Defect database from molecular dynamics simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.

Molecular dynamics simulations have been used to generate a comprehensive database of surviving defects due to displacement cascades in bulk tungsten. Twenty-one data points of primary knock-on atom (PKA) energies ranging from 100 eV (sub-threshold energy) to 100 keV (~780 × Ed, where Ed = 128 eV is the average displacement threshold energy) have been completed at 300 K, 1025 K and 2050 K. Within this range of PKA energies, two regimes of power-law energy-dependence of the defect production are observed. A distinct power-law exponent characterizes the number of Frenkel pairs produced within each regime. The two regimes intersect atmore » a transition energy which occurs at approximately 250 × Ed. The transition energy also marks the onset of the formation of large self-interstitial atom (SIA) clusters (size 14 or more). The observed defect clustering behavior is asymmetric, with SIA clustering increasing with temperature, while the vacancy clustering decreases. This asymmetry increases with temperature such that at 2050 K (~0.5 Tm) practically no large vacancy clusters are formed, meanwhile large SIA clusters appear in all simulations. The implication of such asymmetry on the long-term defect survival and damage accumulation is discussed. In addition, <100> {110} SIA loops are observed to form directly in the highest energy cascades, while vacancy <100> loops are observed to form at the lowest temperature and highest PKA energies, although the appearance of both the vacancy and SIA loops with Burgers vector of <100> type is relatively rare.« less

In vivo myosin step-size from zebrafish skeletal muscle

PubMed Central

Ajtai, Katalin; Sun, Xiaojing; Takubo, Naoko; Wang, Yihua

2016-01-01

Muscle myosins transduce ATP free energy into actin displacement to power contraction. In vivo, myosin side chains are modified post-translationally under native conditions, potentially impacting function. Single myosin detection provides the ‘bottom-up’ myosin characterization probing basic mechanisms without ambiguities inherent to ensemble observation. Macroscopic muscle physiological experimentation provides the definitive ‘top-down’ phenotype characterizations that are the concerns in translational medicine. In vivo single myosin detection in muscle from zebrafish embryo models for human muscle fulfils ambitions for both bottom-up and top-down experimentation. A photoactivatable green fluorescent protein (GFP)-tagged myosin light chain expressed in transgenic zebrafish skeletal muscle specifically modifies the myosin lever-arm. Strychnine induces the simultaneous contraction of the bilateral tail muscles in a live embryo, causing them to be isometric while active. Highly inclined thin illumination excites the GFP tag of single lever-arms and its super-resolution orientation is measured from an active isometric muscle over a time sequence covering many transduction cycles. Consecutive frame lever-arm angular displacement converts to step-size by its product with the estimated lever-arm length. About 17% of the active myosin steps that fall between 2 and 7 nm are implicated as powerstrokes because they are beyond displacements detected from either relaxed or ATP-depleted (rigor) muscle. PMID:27249818

Apparatus and method for suppressing vibration and displacement of a bellows

DOEpatents

Kuklo, Thomas C.

1985-01-01

Flexible bellows are utilized between two systems, such as a pumping system and a process station, to partially absorb system vibrations and to compensate for misalignment between the systems. It is common practice to either clamp a rigid spacer between flanges of the two systems (FIG. 3B) to separate them from each other, or to maintain the bellows in unsupported relationship between these systems (FIG. 4B). In the former bellows arrangement, the rigid spacer transmits vibratory energy between the two systems and the bellows tends to function as an undamped or underdamped unit that resonates at its own frequency to create additional vibratory energy, transmitted to the systems. In the latter, unsupported bellows arrangement (FIG. 4B), the pressure differential prevalent between the fluid flowing through the bellows and ambient normally causes extension or retraction of the bellows and resulting misalignment problems. The present invention substantially solves the above vibration and misalignment problems by providing an inflatable tube (20) in surrounding relationship about a bellows (14) to suppress vibration and displacement thereof. A method for isolating first and second systems (11,12) from each other to prevent the transmission of vibratory energy therebetween comprises the steps of attaching at least one flexible bellows (14) between the systems (11,12), surrounding the bellows with an inflatable tube (20), and maintaining a predetermined pressure in the tube (20) to urge the tube in flexible contact with at least some of the convolutions of the bellows (14).

Fourfold Clusters of Rovibrational Energies in H2Te Studied With an Ab Initio Potential Energy Function

NASA Technical Reports Server (NTRS)

Jensen, Per; Li, Yan; Hirsch, Gerhard; Buenker, Robert J.; Lee, Timothy J.; Arnold, James O. (Technical Monitor)

1994-01-01

We report an ab initio investigation of the cluster effect (i.e., the formation of nearly degenerate, four member groups of rotation-vibration energy levels at higher J and K(sub a). values) in the H2Te molecule. The potential energy function has been calculated ab initio at a total of 334 molecular geometries by means of the CCSD(T) method where the (1s-4f) core electrons of Te were described by an effective core potential. The values of the potential energy function obtained cover the region up to around 10,000/cm above the equilibrium energy. On the basis of the ab initio potential, the rotation-vibration energy spectra of H2Te-130 and its deuterated isotopomers have been calculated with the MORBID (Morse Oscillator Rigid Bender Internal Dynamics) Hamiltonian and computer program. In particular, we have calculated the rotational energy manifolds for J less than or = 40 in the vibrational ground state, the upsilon(sub 2) state, the "first triad" (the upsilon(sub l)/upsilon(sub 3)/2upsilon(sub 2) interacting vibrational states), and the "second triad" (the upsilon(sub 1) + upsilon(sub 2/upsilon(sub 2) + upsilon(sub 3)/3upsilon(sub 2) states) of H2Te-130. We find that the cluster formation in H2Te is very similar to those of of H2Se and H2S, which we have studied previously. However, contrary to semiclassical predictions, we do not determine any significant displacement of the clusters towards lower J values relative to H2Se. Hence the experimental observation of the cluster states in H2Te will be at least as difficult as in H2Se.

Stress Analysis of Composite Cylindrical Shells with an Elliptical Cutout

NASA Technical Reports Server (NTRS)

Oterkus, E.; Madenci, E.; Nemeth, M. P.

2007-01-01

A special-purpose, semi-analytical solution method for determining the stress and deformation fields in a thin laminated-composite cylindrical shell with an elliptical cutout is presented. The analysis includes the effects of cutout size, shape, and orientation; non-uniform wall thickness; oval-cross-section eccentricity; and loading conditions. The loading conditions include uniform tension, uniform torsion, and pure bending. The analysis approach is based on the principle of stationary potential energy and uses Lagrange multipliers to relax the kinematic admissibility requirements on the displacement representations through the use of idealized elastic edge restraints. Specifying appropriate stiffness values for the elastic extensional and rotational edge restraints (springs) allows the imposition of the kinematic boundary conditions in an indirect manner, which enables the use of a broader set of functions for representing the displacement fields. Selected results of parametric studies are presented for several geometric parameters that demonstrate that analysis approach is a powerful means for developing design criteria for laminated-composite shells.

Stress Analysis of Composite Cylindrical Shells With an Elliptical Cutout

NASA Technical Reports Server (NTRS)

Nemeth, M. P.; Oterkus, E.; Madenci, E.

2005-01-01

A special-purpose, semi-analytical solution method for determining the stress and deformation fields in a thin laminated-composite cylindrical shell with an elliptical cutout is presented. The analysis includes the effects of cutout size, shape, and orientation; nonuniform wall thickness; oval-cross-section eccentricity; and loading conditions. The loading conditions include uniform tension, uniform torsion, and pure bending. The analysis approach is based on the principle of stationary potential energy and uses Lagrange multipliers to relax the kinematic admissibility requirements on the displacement representations through the use of idealized elastic edge restraints. Specifying appropriate stiffness values for the elastic extensional and rotational edge restraints (springs) allows the imposition of the kinematic boundary conditions in an indirect manner, which enables the use of a broader set of functions for representing the displacement fields. Selected results of parametric studies are presented for several geometric parameters that demonstrate that analysis approach is a powerful means for developing design criteria for laminated-composite shells.

Effects of vacancies on atom displacement threshold energy calculations through Molecular Dynamics Methods in BaTiO3

NASA Astrophysics Data System (ADS)

Gonzalez Lazo, Eduardo; Cruz Inclán, Carlos M.; Rodríguez Rodríguez, Arturo; Guzmán Martínez, Fernando; Abreu Alfonso, Yamiel; Piñera Hernández, Ibrahin; Leyva Fabelo, Antonio

2017-09-01

A primary approach for evaluating the influence of point defects like vacancies on atom displacement threshold energies values Td in BaTiO3 is attempted. For this purpose Molecular Dynamics Methods, MD, were applied based on previous Td calculations on an ideal tetragonal crystalline structure. It is an important issue in achieving more realistic simulations of radiation damage effects in BaTiO3 ceramic materials. It also involves irradiated samples under severe radiation damage effects due to high fluency expositions. In addition to the above mentioned atom displacement events supported by a single primary knock-on atom, PKA, a new mechanism was introduced. It corresponds to the simultaneous excitation of two close primary knock-on atoms in BaTiO3, which might take place under a high flux irradiation. Therefore, two different BaTiO3 Td MD calculation trials were accomplished. Firstly, single PKA excitations in a defective BaTiO3 tetragonal crystalline structure, consisting in a 2×2×2 BaTiO3 perovskite like super cell, were considered. It contains vacancies on Ba and O atomic positions under the requirements of electrical charge balance. Alternatively, double PKA excitations in a perfect BaTiO3 tetragonal unit cell were also simulated. On this basis, the corresponding primary knock-on atom (PKA) defect formation probability functions were calculated at principal crystal directions, and compared with the previous one we calculated and reported at an ideal BaTiO3 tetrahedral crystal structure. As a general result, a diminution of Td values arises in present calculations in comparison with those calculated for single PKA excitation in an ideal BaTiO3 crystal structure.

The comparative analysis of rocks' resistance to forward-slanting disc cutters and traditionally installed disc cutters

NASA Astrophysics Data System (ADS)

Zhang, Zhao-Huang; Fei, Sun; Liang, Meng

2016-08-01

At present, disc cutters of a full face rock tunnel boring machine are mostly mounted in the traditional way. Practical use in engineering projects reveals that this installation method not only heavily affects the operation life of disc cutters, but also increases the energy consumption of a full face rock tunnel boring machine. To straighten out this issue, therefore, a rock-breaking model is developed for disc cutters' movement after the research on the rock breaking of forward-slanting disc cutters. Equations of its displacement are established based on the analysis of velocity vector of a disc cutter's rock-breaking point. The functional relations then are brought forward between the displacement parameters of a rock-breaking point and its coordinate through the analysis of micro displacement of a rock-breaking point. Thus, the geometric equations of rock deformation are derived for the forward-slanting installation of disc cutters. With a linear relationship remaining between the acting force and its deformation either before or after the leap breaking, the constitutive relation of rock deformation can be expressed in the form of generalized Hooke law, hence the comparative analysis of the variation in the resistance of rock to the disc cutters mounted in the forward-slanting way with that in the traditional way. It is discovered that with the same penetration, strain of the rock in contact with forward-slanting disc cutters is apparently on the decline, in other words, the resistance of rock to disc cutters is reduced. Thus wear of disc cutters resulted from friction is lowered and energy consumption is correspondingly decreased. It will be useful for the development of installation and design theory of disc cutters, and significant for the breakthrough in the design of full face rock tunnel boring machine.

Contaminants in ventilated filling boxes

NASA Astrophysics Data System (ADS)

Bolster, D. T.; Linden, P. F.

While energy efficiency is important, the adoption of energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. Many low-energy systems, such as displacement or natural ventilation, rely on temperature stratification within the interior environment, always extracting the warmest air from the top of the room. Understanding buoyancy-driven convection in a confined ventilated space is key to understanding the flow that develops with many of these modern low-energy ventilation schemes. In this work we study the transport of an initially uniformly distributed passive contaminant in a displacement-ventilated space. Representing a heat source as an ideal sourced of buoyancy, analytical and numerical models are developed that allow us to compare the average efficiency of contaminant removal between traditional mixing and modern low-energy systems. A set of small-scale analogue laboratory experiments was also conducted to further validate our analytical and numerical solutions.We find that on average traditional and low-energy ventilation methods are similar with regard to pollutant flushing efficiency. This is because the concentration being extracted from the system at any given time is approximately the same for both systems. However, very different vertical concentration gradients exist. For the low-energy system, a peak in contaminant concentration occurs at the temperature interface that is established within the space. This interface is typically designed to sit at some intermediate height in the space. Since this peak does not coincide with the extraction point, displacement ventilation does not offer the same benefits for pollutant flushing as it does for buoyancy removal.

Contributions on Optimizing Approximations in the Study of Melting and Solidification Processes That Occur in Processing by Electro-Erosion

NASA Astrophysics Data System (ADS)

Potra, F. L.; Potra, T.; Soporan, V. F.

We propose two optimization methods of the processes which appear in EDM (Electrical Discharge Machining). First refers to the introduction of a new function approximating the thermal flux energy in EDM machine. Classical researches approximate this energy with the Gauss' function. In the case of unconventional technology the Gauss' bell became null only for r → +∞, where r is the radius of crater produced by EDM. We introduce a cubic spline regression which descends to zero at the crater's boundary. In the second optimization we propose modifications in technologies' work regarding the displacement of the tool electrode to the piece electrode such that the material melting to be realized in optimal time and the feeding speed with dielectric liquid regarding the solidification of the expulsed material. This we realize using the FAHP algorithm based on the theory of eigenvalues and eigenvectors, which lead to mean values of best approximation. [6

Ab initio study of edge effect on relative motion of walls in carbon nanotubes

NASA Astrophysics Data System (ADS)

Popov, Andrey M.; Lebedeva, Irina V.; Knizhnik, Andrey A.; Lozovik, Yurii E.; Potapkin, Boris V.

2013-01-01

Interwall interaction energies of double-walled nanotubes with long inner and short outer walls are calculated as functions of coordinates describing relative rotation and displacement of the walls using van der Waals corrected density functional theory. The magnitude of corrugation and the shape of the potential energy relief are found to be very sensitive to changes of the shorter wall length at subnanometer scale and atomic structure of the edges if at least one of the walls is chiral. Threshold forces required to start relative motion of the short walls and temperatures at which the transition between diffusive and free motion of the short walls takes place are estimated. The edges are also shown to provide a considerable contribution to the barrier to relative rotation of commensurate nonchiral walls. For such walls, temperatures of orientational melting, i.e., the crossover from rotational diffusion to free relative rotation, are estimated. The possibility to produce nanotube-based bolt/nut pairs and nanobearings is discussed.

Variable-Displacement Hydraulic Drive Unit

NASA Technical Reports Server (NTRS)

Lang, D. J.; Linton, D. J.; Markunas, A.

1986-01-01

Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

Hydro-Thermal Fatigue Resistance Measurements on Polymer Interfaces

NASA Astrophysics Data System (ADS)

Gurumurthy, Charan K.; Kramer, Edward J.; Hui, Chung-Yuen

1998-03-01

We have developed a new technique based on a fiber optic displacement sensor for rapid determination of hydro-thermal fatigue crack growth rate per cycle (da/dN) of an epoxy/polyimide interface used in flip chip attach microelectronic assembly. The sample is prepared as a trilayered cantilever beam by capillary flow of the epoxy underfill over a polyimide coated metallic beam. During hydro-thermal cycling the crack growth along the interface (from the free end) changes the displacement of this end of the beam and we measure the free end displacement at the lowest temperature in each hydro-thermal cycle. The change in beam displacement is then converted into crack growth rate (da/dN). da/dN depends on the maximum change in the strain energy release rate of the crack and the phase angle in each cycle. The relation between da/dN and maximum strain energy release rate characterizes the fatigue crack growth resistance of the interface. We have developed and used a simple model anhydride cured and a commercially available PMDA/ODA passivation for this study.

Defect structures induced by high-energy displacement cascades in γ uranium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao, Yinbin; Beeler, Benjamin; Deo, Chaitanya

Displacement cascade simulations were conducted for the c uranium system based on molecular dynamics. A recently developed modified embedded atom method (MEAM) potential was employed to replicate the atomic interactions while an embedded atom method (EAM) potential was adopted to help characterize the defect structures induced by the displacement cascades. The atomic displacement process was studied by providing primary knock-on atoms (PKAs) with kinetic energies from 1 keV to 50 keV. The influence of the PKA incident direction was examined. The defect structures were analyzed after the systems were fully relaxed. The states of the self-interstitial atoms (SIAs) were categorizedmore » into various types of dumbbells, the crowdion, and the octahedral interstitial. The voids were determined to have a polyhedral shape with {110} facets. The size distribution of the voids was also obtained. The results of this study not only expand the knowledge of the microstructural evolution in irradiated c uranium, but also provide valuable references for the radiation-induced defects in uranium alloy fuels.« less

Acoustic Emission Parameters of Three Gorges Sandstone during Shear Failure

NASA Astrophysics Data System (ADS)

Xu, Jiang; Liu, Yixin; Peng, Shoujian

2016-12-01

In this paper, an experimental investigation of sandstone samples from the Three Gorges during shear failure was conducted using acoustic emission (AE) and direct shear tests. The AE count rate, cumulative AE count, AE energy, and amplitude of the sandstone samples were determined. Then, the relationships among the AE signals and shearing behaviors of the samples were analyzed in order to detect micro-crack initiation and propagation and reflect shear failure. The results indicated that both the shear strength and displacement exhibited a logarithmic relationship with the displacement rate at peak levels of stress. In addition, the various characteristics of the AE signals were apparent in various situations. The AE signals corresponded with the shear stress under different displacement rates. As the displacement rate increased, the amount of accumulative damage to each specimen decreased, while the AE energy peaked earlier and more significantly. The cumulative AE count primarily increased during the post-peak period. Furthermore, the AE count rate and amplitude exhibited two peaks during the peak shear stress period due to crack coalescence and rock bridge breakage. These isolated cracks later formed larger fractures and eventually caused ruptures.

Faraday's Law, Lenz's Law, and Conservation of Energy

NASA Astrophysics Data System (ADS)

Wood, Lowell; Rottmann, Ray; Barrera, Regina

2003-03-01

A magnet accelerates upward through a coil and generates an emf that is recorded by a data acquisition system and a computer. Simultaneously, the position of the magnet as a function of time is recorded using a photogate/pulley system. When the circuit is completed by adding an appropriate load resistor, a current that opposes the flux change is generated in the coil. This current causes a magnetic field in the coil that decreases the acceleration of the rising magnet, a fact that is evident from the position versus time data. The energy dissipated by the resistance in the circuit is shown experimentally to equal the loss in mechanical energy of the system to within a few percent, thus demonstrating conservation of energy. The graphs of speed squared versus displacement show the changes in acceleration produced by the interaction of the induced current and the magnet. Students in introductory physics laboratories have successfully performed this experiment and are able to see many relevant features of Faraday's law.

Optical spectra obtained from amorphous films of rubrene: Evidence for predominance of twisted isomer

NASA Astrophysics Data System (ADS)

Kytka, M.; Gisslen, L.; Gerlach, A.; Heinemeyer, U.; Kováč, J.; Scholz, R.; Schreiber, F.

2009-06-01

In order to investigate the optical properties of rubrene we study the vibronic progression of the first absorption band (lowest π →π∗ transition). We analyze the dielectric function ɛ2 of rubrene in solution and thin films using the displaced harmonic oscillator model and derive all relevant parameters of the vibronic progression. The findings are supplemented by density functional calculations using B3LYP hybrid functionals. Our theoretical results for the molecule in two different conformations, i.e., with a twisted or planar tetracene backbone, are in very good agreement with the experimental data obtained for rubrene in solution and thin films. Moreover, a simulation based on the monomer spectrum and the calculated transition energies of the two conformations indicates that the thin film spectrum of rubrene is dominated by the twisted isomer.

Light-induced picosecond rotational disordering of the inorganic sublattice in hybrid perovskites.

PubMed

Wu, Xiaoxi; Tan, Liang Z; Shen, Xiaozhe; Hu, Te; Miyata, Kiyoshi; Trinh, M Tuan; Li, Renkai; Coffee, Ryan; Liu, Shi; Egger, David A; Makasyuk, Igor; Zheng, Qiang; Fry, Alan; Robinson, Joseph S; Smith, Matthew D; Guzelturk, Burak; Karunadasa, Hemamala I; Wang, Xijie; Zhu, Xiaoyang; Kronik, Leeor; Rappe, Andrew M; Lindenberg, Aaron M

2017-07-01

Femtosecond resolution electron scattering techniques are applied to resolve the first atomic-scale steps following absorption of a photon in the prototypical hybrid perovskite methylammonium lead iodide. Following above-gap photoexcitation, we directly resolve the transfer of energy from hot carriers to the lattice by recording changes in the mean square atomic displacements on 10-ps time scales. Measurements of the time-dependent pair distribution function show an unexpected broadening of the iodine-iodine correlation function while preserving the Pb-I distance. This indicates the formation of a rotationally disordered halide octahedral structure developing on picosecond time scales. This work shows the important role of light-induced structural deformations within the inorganic sublattice in elucidating the unique optoelectronic functionality exhibited by hybrid perovskites and provides new understanding of hot carrier-lattice interactions, which fundamentally determine solar cell efficiencies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Xiaoxi; Tan, Liang Z.; Shen, Xiaozhe

Femtosecond resolution electron scattering techniques are applied to resolve the first atomic-scale steps following absorption of a photon in the prototypical hybrid perovskite methylammonium lead iodide. Following above-gap photoexcitation, we directly resolve the transfer of energy from hot carriers to the lattice by recording changes in the mean square atomic displacements on 10-ps time scales. Measurements of the time-dependent pair distribution function show an unexpected broadening of the iodine-iodine correlation function while preserving the Pb-I distance. This indicates the formation of a rotationally disordered halide octahedral structure developing on picosecond time scales. Here, this work shows the important role ofmore » light-induced structural deformations within the inorganic sublattice in elucidating the unique optoelectronic functionality exhibited by hybrid perovskites and provides new understanding of hot carrier-lattice interactions, which fundamentally determine solar cell efficiencies.« less

Optical spectra obtained from amorphous films of rubrene: Evidence for predominance of twisted isomer.

PubMed

Kytka, M; Gisslen, L; Gerlach, A; Heinemeyer, U; Kovác, J; Scholz, R; Schreiber, F

2009-06-07

In order to investigate the optical properties of rubrene we study the vibronic progression of the first absorption band (lowest pi-->pi( *) transition). We analyze the dielectric function epsilon(2) of rubrene in solution and thin films using the displaced harmonic oscillator model and derive all relevant parameters of the vibronic progression. The findings are supplemented by density functional calculations using B3LYP hybrid functionals. Our theoretical results for the molecule in two different conformations, i.e., with a twisted or planar tetracene backbone, are in very good agreement with the experimental data obtained for rubrene in solution and thin films. Moreover, a simulation based on the monomer spectrum and the calculated transition energies of the two conformations indicates that the thin film spectrum of rubrene is dominated by the twisted isomer.

General Series Solutions for Stresses and Displacements in an Inner-fixed Ring

NASA Astrophysics Data System (ADS)

Jiao, Yongshu; Liu, Shuo; Qi, Dexuan

2018-03-01

The general series solution approach is provided to get the stress and displacement fields in the inner-fixed ring. After choosing an Airy stress function in series form, stresses are expressed by infinite coefficients. Displacements are obtained by integrating the geometric equations. For an inner-fixed ring, the arbitrary loads acting on outer edge are extended into two sets of Fourier series. The zero displacement boundary conditions on inner surface are utilized. Then the stress (and displacement) coefficients are expressed by loading coefficients. A numerical example shows the validity of this approach.

Patient satisfaction after open reduction and internal fixation through lateral extensile approach in displaced intraarticular calcaneal fractures (Sander's type II and III).

PubMed

Kavin, Khatri; Vijay, Sharma; Devendra, Lakhotia; Kamran, Farooque

2016-01-01

To determine patient satisfaction in the patients of displaced intraarticular calcaneal fractures treated with standard lateral approach. The patients of displaced calcaneal fractures (Sander's type II and III) treated between March 2009 and March 2012 were included in the retrospective review and functional outcome was evaluated using American Orthopaedic Foot and Ankle Society (AOFAS) hind foot score, Creighton Nebraska Health Foundation Assessment (CNHFA) scale and foot function index (FFI). The cohort included 26 patients (19 males: seven were females) with a mean age of 38.16 ± 13.53 years (range 18-64 years). The mean period of follow-up was 24.42 ± 6.68 months. The patients achieved good functional scores after anatomical reduction of the fracture. The complication rate was low following strict inclusion criteria. Careful patient selection in displaced intraarticular calcaneal fractures treated through lateral extensile approach achieves good patient satisfaction.

[Osteosynthesis by tension band wiring of displaced fractures of the olecranon].

PubMed

Doursounian, L; Prevot, O; Touzard, R C

1994-01-01

Fifty-two displaced olecranon fractures in adults were treated over a 5-year period. Minimum follow-up was 6 months. Forty-eight fractures were operated and 38 were treated by tension band wiring technique. This technique, applied for all types of fractures, gave good functional results in 33 cases (87%) and fair functional results in 5 cases. Complications include 1 pseudarthrosis, 2 loss of reduction, 2 transient tourniquet palsy and 13 skin problems due to wire protrusion. Tension band wiring is a simple safe and effective technique for displaced olecranon fractures but often requires K-wire removal.

Sequential strand displacement beacon for detection of DNA coverage on functionalized gold nanoparticles.

PubMed

Paliwoda, Rebecca E; Li, Feng; Reid, Michael S; Lin, Yanwen; Le, X Chris

2014-06-17

Functionalizing nanomaterials for diverse analytical, biomedical, and therapeutic applications requires determination of surface coverage (or density) of DNA on nanomaterials. We describe a sequential strand displacement beacon assay that is able to quantify specific DNA sequences conjugated or coconjugated onto gold nanoparticles (AuNPs). Unlike the conventional fluorescence assay that requires the target DNA to be fluorescently labeled, the sequential strand displacement beacon method is able to quantify multiple unlabeled DNA oligonucleotides using a single (universal) strand displacement beacon. This unique feature is achieved by introducing two short unlabeled DNA probes for each specific DNA sequence and by performing sequential DNA strand displacement reactions. Varying the relative amounts of the specific DNA sequences and spacing DNA sequences during their coconjugation onto AuNPs results in different densities of the specific DNA on AuNP, ranging from 90 to 230 DNA molecules per AuNP. Results obtained from our sequential strand displacement beacon assay are consistent with those obtained from the conventional fluorescence assays. However, labeling of DNA with some fluorescent dyes, e.g., tetramethylrhodamine, alters DNA density on AuNP. The strand displacement strategy overcomes this problem by obviating direct labeling of the target DNA. This method has broad potential to facilitate more efficient design and characterization of novel multifunctional materials for diverse applications.

AVERT Main Module Quick Start Guide

EPA Pesticide Factsheets

Learn how to get started with the AVERT tool, which guides non-experts in evaluating county-level emissions displaced at electric power plants by energy efficiency and renewable energy policies and programs.

Site Competition During Coadsorption of Acetone with Methanol and Water on TiO2(110)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Mingmin; Henderson, Michael A.

2011-08-02

The competitive interaction between acetone and two solvent molecules (methanol and water) for surface sites on rutile TiO2(110) was studied using temperature programmed desorption (TPD). On a vacuum reduced TiO2(110) surface, which possessed ~5% oxygen vacancy sites, excess methanol displaced preadsorbed acetone molecules to weakly bound and physisorbed desorption states below 200 K, whereas acetone was stabilized to 250 K against displacement by methanol on an oxidized surface through formation of an acetone-diolate species. These behaviors of acetone differ from the competitive interactions between acetone and water in that acetone is less susceptible to displacement by water. Examination of acetone+methanolmore » and acetone+water multilayer combinations shows that acetone is more compatible in water-ice films than in methanol-ice films, presumably because water has greater potential as a hydrogen-bond donor than does methanol. Acetone molecules displaced from the TiO2(110) surface by water are more likely to be retained in the near-surface region, having a greater opportunity to revisit the surface, than when methanol is used as a coadsorbate. This work was supported by the US Department of Energy Basic Energy Sciences' Chemical Sciences, Geosciences & Biosciences Division. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less

Naturally Inspired Firefly Controller For Stabilization Of Double Inverted Pendulum

NASA Astrophysics Data System (ADS)

Srikanth, Kavirayani; Nagesh, Gundavarapu

2015-12-01

A double inverted pendulum plant as an established model that is analyzed as part of this work was tested under the influence of time delay, where the controller was fine tuned using a firefly algorithm taking into considering the fitness function of variation of the cart position and to minimize the cart position displacement and still stabilize it effectively. The naturally inspired algorithm which imitates the fireflies definitely is an energy efficient method owing to the inherent logic of the way the fireflies respond collectively and has shown that critical time delays makes the system healthy.

Peeling flexible beams in viscous fluids: Rigidity and extensional compliance

NASA Astrophysics Data System (ADS)

Dhong, Charles; Fréchette, Joëlle

2017-01-01

We describe small angle peeling measurements in completely submerged environments to study the coupling between viscous forces and the mechanical properties of the plates being peeled. During the experiments, the plates resist motion because of lubrication forces while van der Waals forces between the plates and the static surface are negligible. In particular, we study the role played by flexural rigidity in the force-displacement curves and in the energy release rate. We show that the coupling between the viscous forces and the flexural rigidity of the plates dictates the shape and magnitude of the force-displacement curves. We develop simple scaling relationships that combine the lubrication forces with an Euler-Bernoulli beam to extract how the peak force and energy release rates depend on the ratio between rigidity and viscosity, and show good agreement between the predictions and experimental results. We also show that increasing the extensional compliance leads to a decrease in both the force-displacement curve and in the energy release rate. We then demonstrate that this reduction can be interpreted in terms of a stress decay length.

Galvanic displacement reaction and rapid thermal annealing in size/shape controlling silver nanoparticles on silicon substrate

NASA Astrophysics Data System (ADS)

Ghosh, Tapas; Satpati, Biswarup

2017-05-01

The effect of the thermal annealing on silver nanoparticles deposited on silicon surface has been studied. The silver nanoparticles have been deposited by the galvanic displacement reaction. Rapid thermal annealing (RTA) has been performed on the Si substrate, containing the silver nanoparticles. The scanning transmission electron microscopy (STEM), energy dispersive X-ray (EDX) spectroscopy and scanning electron microscopy (SEM) study show that the galvanic displacement reaction and subsequent rapid thermal annealing could lead to well separated and spherical shaped larger silver nanoparticles on silicon substrate.

Molecular dynamics studies of displacement cascades in Fe-Y{sub 2}TiO{sub 5} system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dholakia, Manan, E-mail: manan@igcar.gov.in; Chandra, Sharat; Jaya, S. Mathi

The effect of displacement cascade on Fe-Y{sub 2}TiO{sub 5} bilayer is studied using classical molecular dynamics simulations. Different PKA species – Fe, Y, Ti and O – with the same PKA energy of 8 keV are used to produce displacement cascades that encompass the interface. It is shown that Ti atom has the highest movement in the ballistic regime of cascades which can lead to Ti atoms moving out of the oxide clusters into the Fe matrix in ODS alloys.

Treatment options and outcome after bony avulsion of the flexor digitorum profundus tendon: a review of 29 cases.

PubMed

Halát, Gabriel; Negrin, Lukas; Erhart, Jochen; Ristl, Robin; Hajdu, Stefan; Platzer, Patrick

2017-02-01

The objective of this retrospective review was to evaluate the functional and esthetic outcomes in patients with non- or minimally (<2 mm), and severely (>2 mm) displaced bony avulsions of the flexor digitorum profundus (FDP) tendon. Between 1996 and 2010, 29 patients with a bony avulsion of the FDP tendon were treated. The displacement magnitude of the avulsed fragment determined, whether conservative or surgical treatment was performed. Persisting functional deficit, radiological findings, remaining disabilities using the Disability of the Arm, Shoulder, and Hand (DASH) score, as well as treatment-related deformities and complications were evaluated retrospectively and at a mean follow-up of 7 years. In 16 patients, conservative therapy by initial static splinting due to a fragment displacement of <2 mm was conducted. These patients reported no functional impairment at follow-up. In 13 cases, major displacement (>2 mm) of the bony fragment led to an open reconstruction of the avulsion injury either by screw fixation or a Lengemann pull-out wire. In a majority, an extension deficit in the DIP joint and a decrease of tip pinch strength by 25% was present at follow-up. In five patients, peri- or short-term postoperative complications occurred and in five, a nail deformity remained. DASH score revealed satisfying results after both therapeutic approaches. Conservative treatment in non- or minimally displaced avulsions leads to satisfying functional results. Patients receiving surgery after major fragment displacement need to be aware of a possible impaired ROM at the DIP joint. The use of the Lengemann pull-out wire may place patients at an increased complication risk and frequently induces nail deformities. Therapeutic, level IV.

Waves: Internal Tides

NASA Technical Reports Server (NTRS)

Ray, Richard D.

1999-01-01

Oceanic internal tides are internal waves with tidal periodicities. They are ubiquitous throughout the ocean, although generally more pronounced near large bathymetric features such as mid-ocean ridges and continental slopes. The internal vertical displacements associated with these waves can be extraordinarily large. Near some shelf breaks where the surface tides are strong, internal displacements (e.g., of an isothermal surface) can exceed 200 meters. Displacements of 10 meters in the open ocean are not uncommon. The associated current velocities are usually comparable to or larger than the currents of the surface tide. On continental shelves internal tides can occasionally generate packets of internal solitons, which are detectable in remote sensing imagery. Other common nonlinear features are generation of higher harmonics (e.g., 6-hr waves) and wave breaking. Internal tides are known to be an important energy source for mixing of shelf waters. Recent research suggests that they may also be a significant energy source for deep-ocean mixing.

Ultrafast Charge Transfer of a Valence Double Hole in Glycine Driven Exclusively by Nuclear Motion

NASA Astrophysics Data System (ADS)

Li, Zheng; Vendrell, Oriol; Santra, Robin

2015-10-01

We explore theoretically the ultrafast transfer of a double electron hole between the functional groups of glycine after K -shell ionization and subsequent Auger decay. Although a large energy gap of about 15 eV initially exists between the two electronic states involved and coherent electronic dynamics play no role in the hole transfer, we find that the double hole is transferred within 3 to 4 fs between both functional ends of the glycine molecule driven solely by specific nuclear displacements and non-Born-Oppenheimer effects. The nuclear displacements along specific vibrational modes are of the order of 15% of a typical chemical bond between carbon, oxygen, and nitrogen atoms and about 30% for bonds involving hydrogen atoms. The time required for the hole transfer corresponds to less than half a vibrational period of the involved nuclear modes. This finding challenges the common wisdom that nuclear dynamics of the molecular skeleton are unimportant for charge transfer processes at the few-femtosecond time scale and shows that they can even play a prominent role. It also indicates that in x-ray imaging experiments, in which ionization is unavoidable, valence electron redistribution caused by nuclear dynamics might be much faster than previously anticipated. Thus, non-Born-Oppenheimer effects may affect the apparent electron densities extracted from such measurements.

Synthesis, characterization and lithium-ion migration dynamics simulation of LiFe1- x T x PO4 (T = Mn, Co, La and Ce) doping cathode material for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Xiao, Yi; Zhang, Fu Chun; Han, Jeong In

2016-11-01

LiFePO4 was doped by metallic cation in Fe sites via ball milling by a solid-state reaction method synthesis, and with very low-level doping of these samples, such as Li0.95T0.05FePO4 (where T = Mn2+, Co2+, La3+, Ce4+). The effects of doping were studied by X-ray diffraction pattern, Raman shift, scanning electronic microscopy and energy-dispersive X-ray spectroscopy as sample characterizations. The results indicate that these dopants have no significant effect on the structure of the material, but considerably improve its electrochemical behavior. First-principles calculations were used to obtain the migration pathway of Li ions along the one-dimensional (010) direction in LiFePO4, and molecular dynamics simulation was used to investigate the lithium-ion diffusion coefficients ( D Li) inside LiFePO4, which were derived from the slope of the mean square displacement versus time plots. The evolution of the structure during the simulation was analyzed by the radial distribution function to obtain the data, and radial distribution functions and mean square displacements were used to confirm the formation of crystalline units and the evolution of structure.

Ultrafast Charge Transfer of a Valence Double Hole in Glycine Driven Exclusively by Nuclear Motion.

PubMed

Li, Zheng; Vendrell, Oriol; Santra, Robin

2015-10-02

We explore theoretically the ultrafast transfer of a double electron hole between the functional groups of glycine after K-shell ionization and subsequent Auger decay. Although a large energy gap of about 15 eV initially exists between the two electronic states involved and coherent electronic dynamics play no role in the hole transfer, we find that the double hole is transferred within 3 to 4 fs between both functional ends of the glycine molecule driven solely by specific nuclear displacements and non-Born-Oppenheimer effects. The nuclear displacements along specific vibrational modes are of the order of 15% of a typical chemical bond between carbon, oxygen, and nitrogen atoms and about 30% for bonds involving hydrogen atoms. The time required for the hole transfer corresponds to less than half a vibrational period of the involved nuclear modes. This finding challenges the common wisdom that nuclear dynamics of the molecular skeleton are unimportant for charge transfer processes at the few-femtosecond time scale and shows that they can even play a prominent role. It also indicates that in x-ray imaging experiments, in which ionization is unavoidable, valence electron redistribution caused by nuclear dynamics might be much faster than previously anticipated. Thus, non-Born-Oppenheimer effects may affect the apparent electron densities extracted from such measurements.

Atomic-scale properties of Ni-based FCC ternary, and quaternary alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tamm, Artur; Aabloo, Alvo; Klintenberg, Mattias

2015-08-26

The aim of our study is to characterize some atomic-scale properties of Ni-based FCC multicomponent alloys. For this purpose, we use Monte Carlo method combined with density functional theory calculations to study short-range order (SRO), atomic displacements, electronic density of states, and magnetic moments in equimolar ternary NiCrCo, and quaternary NiCrCoFe alloys. The salient features for the ternary alloy are a negative SRO parameter between Ni Cr and a positive between Cr Cr pairs as well as a weakly magnetic state. For the quaternary alloy we predict negative SRO parameter for Ni Cr and Ni Fe pairs and positive formore » Cr Cr and Fe Fe pairs. Atomic displacements for both ternary and quaternary alloys are negligible. In contrast to the ternary, the quaternary alloy shows a complex magnetic structure. The electronic structure of the ternary and quaternary alloys shows differences near the Fermi energy between a random solid solution and the predicted structure with SRO. Despite that, the calculated EXAFS spectra does not show enough contrast to discriminate between random and ordered structures. Finally, the predicted SRO has an impact on point-defect energetics, electron phonon coupling and thermodynamic functions and thus, SRO should not be neglected when studying properties of these two alloys.« less

New Insights on Tsunami Genesis and Energy Source

NASA Astrophysics Data System (ADS)

Song, Y. T.; Mohtat, A.; Yim, S. C.

2017-12-01

Conventional tsunami theories suggest that earthquakes with significant vertical motions are more likely to generate tsunamis. In tsunami models, the vertical seafloor elevation is directly transferred to the sea-surface as the only initial condition. However, evidence from the 2011 Tohoku earthquake indicates otherwise; the vertical seafloor uplift was only 3 5 meters, too small to account for the resultant tsunami. Surprisingly, the horizontal displacement was undeniably larger than anyone's expectation; about 60 meters at the frontal wedge of the fault plate, the largest slip ever recorded by in-situ instruments. The question is whether the horizontal motion of seafloor slopes had enhanced the tsunami to become as destructive as observed. In this study, we provide proof: (1) Combining various measurements from the 2011 Tohoku event, we show that the earthquake transferred a total energy of 3.1e+15 joule to the ocean, in which the potential energy (PE) due to the vertical seafloor elevation (including seafloor uplift/subsidence plus the contribution from the horizontal displacement) was less than a half, while the kinetic energy (KE) due to the horizontal displacement velocity of the continental slope contributed a majority portion; (2) Using two modern state-of-the-art wave flumes and a three-dimensional tsunami model, we have reproduced the source energy and tsunamis consistent with observations, including the 2004 Sumatra event. Based on the unified source energy formulation, we offer a competing theory to explain why some earthquakes generate destructive tsunamis, while others do not.

Tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inaoka, Takeshi, E-mail: inaoka@phys.u-ryukyu.ac.jp; Furukawa, Takuro; Toma, Ryo

By means of a hybrid density-functional method, we investigate the tensile-strain effect of inducing the indirect-to-direct band-gap transition and reducing the band-gap energy of Ge. We consider [001], [111], and [110] uniaxial tensility and (001), (111), and (110) biaxial tensility. Under the condition of no normal stress, we determine both normal compression and internal strain, namely, relative displacement of two atoms in the primitive unit cell, by minimizing the total energy. We identify those strain types which can induce the band-gap transition, and evaluate the critical strain coefficient where the gap transition occurs. Either normal compression or internal strain operatesmore » unfavorably to induce the gap transition, which raises the critical strain coefficient or even blocks the transition. We also examine how each type of tensile strain decreases the band-gap energy, depending on its orientation. Our analysis clearly shows that synergistic operation of strain orientation and band anisotropy has a great influence on the gap transition and the gap energy.« less

Apparent Activation Energies Associated with Protein Dynamics on Hydrophobic and Hydrophilic Surfaces

PubMed Central

Langdon, Blake B.; Kastantin, Mark; Schwartz, Daniel K.

2012-01-01

With the use of single-molecule total internal reflection fluorescence microscopy (TIRFM), the dynamics of bovine serum albumin (BSA) and human fibrinogen (Fg) at low concentrations were observed at the solid-aqueous interface as a function of temperature on hydrophobic trimethylsilane (TMS) and hydrophilic fused silica (FS) surfaces. Multiple dynamic modes and populations were observed and characterized by their surface residence times and squared-displacement distributions (surface diffusion). Characteristic desorption and diffusion rates for each population/mode were generally found to increase with temperature, and apparent activation energies were determined from Arrhenius analyses. The apparent activation energies of desorption and diffusion were typically higher on FS than on TMS surfaces, suggesting that protein desorption and mobility were hindered on hydrophilic surfaces due to favorable protein-surface and solvent-surface interactions. The diffusion of BSA on TMS appeared to be activationless for several populations, whereas diffusion on FS always exhibited an apparent activation energy. All activation energies were small in absolute terms (generally only a few kBT), suggesting that most adsorbed protein molecules are weakly bound and move and desorb readily under ambient conditions. PMID:22713578

Hyoid Displacement in Post-Treatment Cancer Patients: Preliminary Findings

ERIC Educational Resources Information Center

Zu, Yihe; Yang, Zhenyu; Perlman, Adrienne L.

2011-01-01

Purpose: Dysphagia after head and neck cancer treatment is a health care issue; in some cases, the cause of death is not cancer but, rather, the passage of food or liquid into the lungs. Hyoid displacement is known to be important to safe swallowing function. The purpose of this study was to evaluate hyoid displacement after cancer treatment.…

Temporomandibular joint disorder in a patient with multiple sclerosis--review of literature with a clinical report.

PubMed

Badel, Tomislav; Carek, Andreja; Podoreski, Dijana; Pavicin, Ivana Savić; Lovko, Sandra Kocijan

2010-09-01

Temporomandibular disorders are a form of musculoskeletal disorders, which reduce the function of stomatognathic system and they are related to some other diseases causing painful conditions and disorders of oral function. The aim of this paper is to describe a one year follow up clinical case of a female patient with comorbid multiple sclerosis and a relatively rare form of articular disc disorder. Primary clinical diagnostics encompassed manual methods of TMJ examination. Definite diagnosis included radiologic examination. Clinical hyperextensive condyle position was palpated bilaterally and subsequently confirmed by a functional panoramic radiograph of TMJ. The anterior displacement of disc with reduction was diagnosed by magnetic resonance and in the right joint there was a disc displacement upon excursive movement. From relevant literature, the relationship of a number of diseases that can be related to functional disorder of the orofacial system, such as multiple sclerosis, has been described from many aspects. Also, apart from the standard classification of one form of anterior displacement of the disc, made primarily by magnetic resonance, cases of disc displacement upon excursive mandibular movement can rarely be found in literature.

The Effects of Triggering Mechanisms on the Energy Absorption Capability of Circular Jute/Epoxy Composite Tubes under Quasi-Static Axial Loading

NASA Astrophysics Data System (ADS)

Sivagurunathan, Rubentheran; Lau Tze Way, Saijod; Sivagurunathan, Linkesvaran; Yaakob, Mohd. Yuhazri

2018-01-01

The usage of composite materials have been improving over the years due to its superior mechanical properties such as high tensile strength, high energy absorption capability, and corrosion resistance. In this present study, the energy absorption capability of circular jute/epoxy composite tubes were tested and evaluated. To induce the progressive crushing of the composite tubes, four different types of triggering mechanisms were used which were the non-trigger, single chamfered trigger, double chamfered trigger and tulip trigger. Quasi-static axial loading test was carried out to understand the deformation patterns and the load-displacement characteristics for each composite tube. Besides that, the influence of energy absorption, crush force efficiency, peak load, mean load and load-displacement history were examined and discussed. The primary results displayed a significant influence on the energy absorption capability provided that stable progressive crushing occurred mostly in the triggered tubes compared to the non-triggered tubes. Overall, the tulip trigger configuration attributed the highest energy absorption.

Molecular dynamics simulations of high energy cascade in ordered alloys: Defect production and subcascade division

NASA Astrophysics Data System (ADS)

Crocombette, Jean-Paul; Van Brutzel, Laurent; Simeone, David; Luneville, Laurence

2016-06-01

Displacement cascades have been calculated in two ordered alloys (Ni3Al and UO2) in the molecular dynamics framework using the CMDC (Cell Molecular Dynamics for Cascade) code (J.-P. Crocombette and T. Jourdan, Nucl. Instrum. Meth. B 352, 9 (2015)) for energies ranking between 0.1 and 580 keV. The defect production has been compared to the prediction of the NRT (Norgett, Robinson and Torrens) standard. One observes a decrease with energy of the number of defects compared to the NRT prediction at intermediate energies but, unlike what is commonly observed in elemental solids, the number of produced defects does not always turn to a linear variation with ballistic energy at high energies. The fragmentation of the cascade into subcascades has been studied through the analysis of surviving defect pockets. It appears that the common knowledge equivalence of linearity of defect production and subcascades division does not hold in general for alloys. We calculate the average number of subcascades and average number of defects per subcascades as a function of ballistic energy. We find an unexpected variety of behaviors for these two average quantities above the threshold for subcascade formation.

Σ 3 (111 ) grain boundary of body-centered cubic Ti-Mo and Ti-V alloys: First-principles and model calculations

NASA Astrophysics Data System (ADS)

Yan, Jia-Yi; Ehteshami, Hossein; Korzhavyi, Pavel A.; Borgenstam, Annika

2017-07-01

The energetics and atomic structures of Σ 3 [1 1 ¯0 ] (111 ) grain boundary (GB) of body-centered cubic (bcc) Ti-Mo and Ti-V alloys are investigated using density-functional-theory calculations and virtual crystal approximation. The electron density in bcc structure and the atomic displacements and excess energy of the GB are correlated to bcc-ω phase stability. Model calculations based on pairwise interplanar interactions successfully reproduce the chemical part of GB energy. The chemical GB energy can be expressed as a sum of excess pairwise interactions between bcc (111) layers, which are obtained from Gaussian elimination of the total energies of a number of periodic structures. The energy associated with the relaxation near the GB is solved by numerical minimization using the derivatives of the excess interactions. Anharmonic interlayer interactions are necessary for obtaining accurate relaxation energy and excess GB volume from model calculations. The effect of GB on vibrational spectrum is also investigated. Segregation energies of B and Y to a substitutional site on the GB plane are calculated. Preliminary results suggest that Y tends to segregate, while B tends to antisegregate.

Ab initio molecular dynamics simulations of AlN responding to low energy particle radiation

NASA Astrophysics Data System (ADS)

Xi, Jianqi; Liu, Bin; Zhang, Yanwen; Weber, William J.

2018-01-01

Ab initio molecular dynamics simulations of low energy recoil events in wurtzite AlN have been performed to determine threshold displacement energies, defect production and evolution mechanisms, role of partial charge transfer during the process, and the influence of irradiation-induced defects on the properties of AlN. The results show that the threshold displacement energies, Ed, along the direction parallel to the basal planes are smaller than those perpendicular to the basal planes. The minimum Ed values are determined to be 19 eV and 55 eV for N and Al atom, respectively, which occur along the [ 1 ¯ 1 ¯ 20 ] direction. In general, the threshold displacement energies for N are smaller than those for Al atom, indicating the N defects would be dominant under irradiation. The defect production mechanisms have been analyzed. It is found that charge transfer and redistribution for both the primary knock-on atom and the subsequent recoil atoms play a significant role in defect production and evolution. Similar to the trend in oxide materials, there is a nearly linear relationship between Ed and the total amount of charge transfer at the potential energy peak in AlN, which provides guidance on the development of charge-transfer interatomic potentials for classic molecular dynamics simulations. Finally, the response behavior of AlN to low energy irradiation is qualitatively investigated. The existence of irradiation-induced defects significantly modifies the electronic structure, and thus affects the magnetic, electronic and optical properties of AlN. These findings further enrich the understanding of defects in the wide bandgap semiconductor of AlN.

The Post-Processing Approach in the Finite Element Method. Part 1. Calculation of Displacements, Stresses, and other Higher Derivatives of the Displacements.

DTIC Science & Technology

1982-12-01

Were the influence function (Green’s function) known for this point, then we could take i=O and 0 would be expressible in terms of the input data...alone. So (1.1) would take the form 4=R . Of course, the influence function is not in general available. At the other extreme, if we take to be the Dirac...where n is some integer, which, for the moment, will remain arbitrary. If we select for the influence function (Green’s function), then (2.5a) and

Visual analysis of immiscible displacement processes in porous media under ultrasound effect

NASA Astrophysics Data System (ADS)

Naderi, Khosrow; Babadagli, Tayfun

2011-05-01

The effect of sonic waves, in particular, ultrasonic radiation, on immiscible displacement in porous media and enhanced oil recovery has been of interest for more than five decades. Attempts were made to investigate the effect through core scale experimental or theoretical models. Visual experiments are useful to scrutinize the reason for improved oil recovery under acoustic waves of different frequency but are not abundant in literature. In this paper, we report observations and analyses as to the effects of ultrasonic energy on immiscible displacement and interaction of the fluid matrix visually in porous media through two-dimensional (2D) sand pack experiments. 2D glass bead models with different wettabilities were saturated with different viscosity oils and water was injected into the models. The experiments were conducted with and without ultrasound. Dynamic water injection experiments were preferred as they had both viscous and capillary forces in effect. The displacement patterns were evaluated both in terms of their shape, size, and the interface characteristics quantitatively and qualitatively to account for the effects of ultrasonic waves on the displacement and the reason for increased oil production under this type of sonic wave. More compact clusters were observed when ultrasonic energy was present in water-wet systems. In the oil-wet cases, more oil was produced after breakthrough when ultrasound was applied and no compact clusters were formed in contrast to the water-wet cases.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoller, Roger E; Nordlund, Kai; Melerba, L

The processes that give rise to changes in the microstructure and the physical and mechanical properties of materials exposed to energetic particles are initiated by essentially elastic collisions between atoms in what has been called an atomic displacement cascade. The formation and evolution of this primary radiation damage mechanism are described to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the primary variables cascade energy and irradiation temperature are discussed, along with a range of secondary factors that can influence damage formation.Radiation-inducedmore » changes in microstructure and mechanical properties in structural materials are the result of a complex set of physical processes initiated by the collision between an energetic particle (neutron or ion) and an atom in the lattice. This primary damage event is called an atomic displacement cascade. The simplest description of a displacement cascade is to view it as a series of many billiard-ball-like elastic collisions among the atoms in the material. This chapter describes the formation and evolution of this primary radiation damage mechanism to provide an overview of how stable defects are formed by displacement cascades, as well as the nature and morphology of the defects themselves. The impact of the relevant variables such as cascade energy and irradiation temperature is discussed, and defect formation in different materials is compared.« less

Linearization of Positional Response Curve of a Fiber-optic Displacement Sensor

NASA Astrophysics Data System (ADS)

Babaev, O. G.; Matyunin, S. A.; Paranin, V. D.

2018-01-01

Currently, the creation of optical measuring instruments and sensors for measuring linear displacement is one of the most relevant problems in the area of instrumentation. Fiber-optic contactless sensors based on the magneto-optical effect are of special interest. They are essentially contactless, non-electrical and have a closed optical channel not subject to contamination. The main problem of this type of sensors is the non-linearity of their positional response curve due to the hyperbolic nature of the magnetic field intensity variation induced by moving the magnetic source mounted on the controlled object relative to the sensing element. This paper discusses an algorithmic method of linearizing the positional response curve of fiber-optic displacement sensors in any selected range of the displacements to be measured. The method is divided into two stages: 1 - definition of the calibration function, 2 - measurement and linearization of the positional response curve (including its temperature stabilization). The algorithm under consideration significantly reduces the number of points of the calibration function, which is essential for the calibration of temperature dependence, due to the use of the points that randomly deviate from the grid points with uniform spacing. Subsequent interpolation of the deviating points and piecewise linear-plane approximation of the calibration function reduces the microcontroller storage capacity for storing the calibration function and the time required to process the measurement results. The paper also presents experimental results of testing real samples of fiber-optic displacement sensors.

On a 3-D singularity element for computation of combined mode stress intensities

NASA Technical Reports Server (NTRS)

Atluri, S. N.; Kathiresan, K.

1976-01-01

A special three-dimensional singularity element is developed for the computation of combined modes 1, 2, and 3 stress intensity factors, which vary along an arbitrarily curved crack front in three dimensional linear elastic fracture problems. The finite element method is based on a displacement-hybrid finite element model, based on a modified variational principle of potential energy, with arbitrary element interior displacements, interelement boundary displacements, and element boundary tractions as variables. The special crack-front element used in this analysis contains the square root singularity in strains and stresses, where the stress-intensity factors K(1), K(2), and K(3) are quadratically variable along the crack front and are solved directly along with the unknown nodal displacements.

Optimization of High-Dimensional Functions through Hypercube Evaluation

PubMed Central

Abiyev, Rahib H.; Tunay, Mustafa

2015-01-01

A novel learning algorithm for solving global numerical optimization problems is proposed. The proposed learning algorithm is intense stochastic search method which is based on evaluation and optimization of a hypercube and is called the hypercube optimization (HO) algorithm. The HO algorithm comprises the initialization and evaluation process, displacement-shrink process, and searching space process. The initialization and evaluation process initializes initial solution and evaluates the solutions in given hypercube. The displacement-shrink process determines displacement and evaluates objective functions using new points, and the search area process determines next hypercube using certain rules and evaluates the new solutions. The algorithms for these processes have been designed and presented in the paper. The designed HO algorithm is tested on specific benchmark functions. The simulations of HO algorithm have been performed for optimization of functions of 1000-, 5000-, or even 10000 dimensions. The comparative simulation results with other approaches demonstrate that the proposed algorithm is a potential candidate for optimization of both low and high dimensional functions. PMID:26339237

Hip Surveillance in Children with Cerebral Palsy.

PubMed

Huser, Aaron; Mo, Michelle; Hosseinzadeh, Pooya

2018-04-01

The hip is the second most common involved joint in cerebral palsy. Hip displacement occurs in more than 33% of children with cerebral palsy, with a higher prevalence in nonambulatory children. Hip displacement in this population is typically progressive. Hip dislocation can result in pain and difficulty with sitting and perineal care. Since early stage of hip displacement can be silent, and hip surveillance programs are recommended. Most programs use the degree of hip dysplasia and Growth Motor Function Classification System level for screening recommendations. Treatment depends on the degree of dysplasia, functional status of the patient, and patient's age. Copyright © 2017 Elsevier Inc. All rights reserved.

Anisotropic mean-square displacements in two-dimensional colloidal crystals of tilted dipoles

NASA Astrophysics Data System (ADS)

Froltsov, V. A.; Likos, C. N.; Löwen, H.; Eisenmann, C.; Gasser, U.; Keim, P.; Maret, G.

2005-03-01

Superparamagnetic colloidal particles confined to a flat horizontal air-water interface in an external magnetic field, which is tilted relative to the interface, form anisotropic two-dimensional crystals resulting from their mutual dipole-dipole interactions. Using real-space experiments and harmonic lattice theory we explore the mean-square displacements of the particles in the directions parallel and perpendicular to the in-plane component of the external magnetic field as a function of the tilt angle. We find that the anisotropy of the mean-square displacement behaves nonmonotonically as a function of the tilt angle and does not correlate with the structural anisotropy of the crystal.

van der Waals criticality in AdS black holes: A phenomenological study

NASA Astrophysics Data System (ADS)

Bhattacharya, Krishnakanta; Majhi, Bibhas Ranjan; Samanta, Saurav

2017-10-01

Anti-de Sitter black holes exhibit van der Waals-type phase transition. In the extended phase-space formalism, the critical exponents for any spacetime metric are identical to the standard ones. Motivated by this fact, we give a general expression for the Helmholtz free energy near the critical point, which correctly reproduces these exponents. The idea is similar to the Landau model, which gives a phenomenological description of the usual second-order phase transition. Here, two main inputs are taken into account for the analysis: (a) black holes should have van der Waals-like isotherms, and (b) free energy can be expressed solely as a function of thermodynamic volume and horizon temperature. Resulting analysis shows that the form of Helmholtz free energy correctly encapsulates the features of the Landau function. We also discuss the isolated critical point accompanied by nonstandard values of critical exponents. The whole formalism is then extended to two other criticalities, namely, Y -X and T -S (based on the standard; i.e., nonextended phase space), where X and Y are generalized force and displacement, whereas T and S are the horizon temperature and entropy. We observe that in the former case Gibbs free energy plays the role of Landau function, whereas in the later case, that role is played by the internal energy (here, it is the black hole mass). Our analysis shows that, although the existence of a van der Waals phase transition depends on the explicit form of the black hole metric, the values of the critical exponents are universal in nature.

Influence of specific contacts on the stability and structure of proteins. Theory for the perturbation of a harmonic system.

PubMed Central

Jackson, M B

1987-01-01

The question of how specific contacts within a protein influence its stability and structure is examined within a formal theoretical framework. A mathematical model is developed in which the potential energy of a protein is taken as a harmonic expansion of all of its internal or normal coordinates. With classical statistical mechanics the properties of the system can be derived from this potential energy function. A few new contacts are then introduced as additional energy terms, each having a quadratic dependence on a single internal coordinate. These terms are added as perturbations to the original potential energy, and the attendant changes in the properties of the system are obtained. Exact expressions can be derived for changes in the enthalpy, entropy, and for any arbitrary internal degree of freedom. These quantities are expressed in terms of the parameters of the potential energy functions of the new contacts, and the mean square displacements and positional correlation functions of the internal coordinates. These results provide qualitative insights into the role of contacts in stabilizing a particular conformation. Estimates are given for the entropy of formation of a hydrogen bond in a protein. A criterion is proposed for determining whether a contact is essential to the stability of a protein conformation. This model may be applicable to many experimental systems in which mutant or modified proteins are available that differ by one or a few amino acids. The results may also be useful in thermodynamic analyses of computer simulations. PMID:3828463

Experimental techniques and computational methods toward the estimation of the effective two-phase flow coefficients and multi-scale heterogeneities of soils

NASA Astrophysics Data System (ADS)

Tsakiroglou, C. D.; Aggelopoulos, C. A.; Sygouni, V.

2009-04-01

A hierarchical, network-type, dynamic simulator of the immiscible displacement of water by oil in heterogeneous porous media is developed to simulate the rate-controlled displacement of two fluids at the soil column scale. A cubic network is constructed, where each node is assigned a permeability which is chosen randomly from a distribution function. The intensity of heterogeneities is quantified by the width of the permeability distribution function. The capillary pressure at each node is calculated by combining a generalized Leverett J-function with a Corey type model. Information about the heterogeneity of soils at the pore network scale is obtained by combining mercury intrusion porosimetry (MIP) data with back-scattered scanning electron microscope (BSEM) images [1]. In order to estimate the two-phase flow properties of nodes (relative permeability and capillary pressure functions, permeability distribution function) immiscible and miscible displacement experiments are performed on undisturbed soil columns. The transient responses of measured variables (pressure drop, fluid saturation averaged over five successive segments, solute concentration averaged over three cross-sections) are fitted with models accounting for the preferential flow paths at the micro- (multi-region model) and macro-scale (multi flowpath model) because of multi-scale heterogeneities [2,3]. Simulating the immiscible displacement of water by oil (drainage) in a large netork, at each time step, the fluid saturation and pressure of each node are calculated formulating mass balances at each node, accounting for capillary, viscous and gravity forces, and solving the system of coupled equations. At each iteration of the algorithm, the pressure drop is so selected that the total flow rate of the injected fluid is kept constant. The dynamic large-scale network simulator is used (1) to examine the sensitivity of the transient responses of the axial distribution of fluid saturation and total pressure drop across the network to the permeability distribution function, spatial correlations of permeability, and capillary number, and (2) to estimate the effective (up-scaled) relative permeability functions at the soil column scale. In an attempt to clarify potential effects of the permeability distribution and spatial permeability correlations on the transient responses of the pressure drop across a soil column, signal analysis with wavelets is performed [4] on experimental and simulated results. The transient variation of signal energy and frequency of pressure drop fluctuations at the wavelet domain are correlated with macroscopic properties such as the effective water and oil relative permeabilities of the porous medium, and microscopic properties such as the variation of the permeability distribution of oil-occupied nodes. Toward the solution of the inverse problem, a general procedure is suggested to identify macro-heterogeneities from the fast analysis of pressure drop signals. References 1. Tsakiroglou, C.D. and M.A. Ioannidis, "Dual porosity modeling of the pore structure and transport properties of a contaminated soil", Eur. J. Soil Sci., 59, 744-761 (2008). 2. Aggelopoulos, C.A., and C.D. Tsakiroglou, "Quantifying the Soil Heterogeneity from Solute Dispersion Experiments", Geoderma, 146, 412-424 (2008). 3. Aggelopoulos, C.A., and C.D. Tsakiroglou, "A multi-flow path approach to model immiscible displacement in undisturbed heterogeneous soil columns", J. Contam. Hydrol., in press (2009). 4. Sygouni, V., C.D. Tsakiroglou, and A.C. Payatakes, "Using wavelets to characterize the wettability of porous materials", Phys. Rev. E, 76, 056304 (2007).

Symposium review: Modulating adipose tissue lipolysis and remodeling to improve immune function during the transition period and early lactation of dairy cows.

PubMed

Contreras, G Andres; Strieder-Barboza, Clarissa; De Koster, Jenne

2018-03-01

Despite major advances in our understanding of transition and early lactation cow physiology and the use of advanced dietary, medical, and management tools, at least half of early lactation cows are reported to develop disease and over half of cow deaths occur during the first week of lactation. Excessive lipolysis, usually measured as plasma concentrations of free fatty acids (FFA), is a major risk factor for the development of displaced abomasum, ketosis, fatty liver, and metritis, and may also lead to poor lactation performance. Lipolysis triggers adipose tissue (AT) remodeling that is characterized by enhanced humoral and cell-mediated inflammatory responses and changes in its distribution of cellular populations and extracellular matrix composition. Uncontrolled AT inflammation could perpetuate lipolysis, as we have observed in cows with displaced abomasum, especially in those animals with genetic predisposition for excessive lipolysis responses. Efficient transition cow management ensures a moderate rate of lipolysis that is rapidly reduced as lactation progresses. Limiting FFA release from AT benefits immune function as several FFA are known to promote dysregulation of inflammation. Adequate formulation of pre- and postpartum diet reduces the intensity of AT lipolysis. Additionally, supplementation with niacin, monensin, and rumen-protected methyl donors (choline and methionine) during the transition period is reported to minimize FFA release into systemic circulation. Targeted supplementation of energy sources during early lactation improves energy balance and increases insulin concentration, which limits AT lipolytic responses. This review elaborates on the mechanisms by which uncontrolled lipolysis triggers inflammatory disorders. Details on current nutritional and pharmacological interventions that aid the modulation of FFA release from AT and their effect on immune function are provided. Understanding the inherent characteristics of AT biology in transition and early lactation cows will reduce disease incidence and improve lactation performance. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Light-induced picosecond rotational disordering of the inorganic sublattice in hybrid perovskites

DOE PAGES

Wu, Xiaoxi; Tan, Liang Z.; Shen, Xiaozhe; ...

2017-07-26

Femtosecond resolution electron scattering techniques are applied to resolve the first atomic-scale steps following absorption of a photon in the prototypical hybrid perovskite methylammonium lead iodide. Following above-gap photoexcitation, we directly resolve the transfer of energy from hot carriers to the lattice by recording changes in the mean square atomic displacements on 10-ps time scales. Measurements of the time-dependent pair distribution function show an unexpected broadening of the iodine-iodine correlation function while preserving the Pb-I distance. This indicates the formation of a rotationally disordered halide octahedral structure developing on picosecond time scales. Here, this work shows the important role ofmore » light-induced structural deformations within the inorganic sublattice in elucidating the unique optoelectronic functionality exhibited by hybrid perovskites and provides new understanding of hot carrier-lattice interactions, which fundamentally determine solar cell efficiencies.« less

Dynamic ductile fracture of a central crack

NASA Technical Reports Server (NTRS)

Tsai, Y. M.

1976-01-01

A central crack, symmetrically growing at a constant speed in a two dimensional ductile material subject to uniform tension at infinity, is investigated using the integral transform methods. The crack is assumed to be the Dugdale crack, and the finite stress condition at the crack tip is satisfied during the propagation of the crack. Exact expressions of solution are obtained for the finite stress condition at the crack tip, the crack shape, the crack opening displacement, and the energy release rate. All those expressions are written as the product of explicit dimensional quantities and a nondimensional dynamic correction function. The expressions reduce to the associated static results when the crack speed tends to zero, and the nondimensional dynamic correction functions were calculated for various values of the parameter involved.

Archaeal ribonuclease P proteins have potential for biotechnological applications where precise hybridization of nucleic acids is needed.

PubMed

Miyanoshita, Mitsuru; Nakashima, Takashi; Kakuta, Yoshimitsu; Kimura, Makoto

2015-01-01

Fluorescence resonance energy transfer-based assay showed that archaeal ribonuclease P (RNase P) proteins significantly promoted DNA annealing and strand displacement. Moreover, we found that archaeal RNase P proteins could discriminate nucleotide exchanges in DNA chains via their activity accelerating DNA strand displacement, suggesting that they have potential for biotechnological application to genetic diagnosis.

Fall with Linear Drag and Wien's Displacement Law: Approximate Solution and Lambert Function

ERIC Educational Resources Information Center

Vial, Alexandre

2012-01-01

We present an approximate solution for the downward time of travel in the case of a mass falling with a linear drag force. We show how a quasi-analytical solution implying the Lambert function can be found. We also show that solving the previous problem is equivalent to the search for Wien's displacement law. These results can be of interest for…

Search for R -parity violating supersymmetry with displaced vertices in proton-proton collisions at s = 8 TeV

DOE PAGES

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; ...

2017-01-25

Results are reported from a search for R-parity violating supersymmetry in proton-proton collision events collected by the CMS experiment at a center-of-mass energy of √s = 8 TeV. Here, the data sample corresponds to an integrated luminosity of 17.6 fb –1. This search assumes a minimal flavor violating model in which the lightest supersymmetric particle is a long-lived neutralino or gluino, leading to a signal with jets emanating from displaced vertices. In a sample of events with two displaced vertices, no excess yield above the expectation from standard model processes is observed, and limits are placed on the pair productionmore » cross section as a function of mass and lifetime of the neutralino or gluino. At 95% confidence level, the analysis excludes cross sections above approximately 1 fb for neutralinos or gluinos with mass between 400 and 1500 GeV and mean proper decay length between 1 and 30 mm. Gluino masses are excluded below 1 and 1.3 TeV for mean proper decay lengths of 300 μm an 1 mm, respectively, and below 1.4 TeV for the range 2–30 mm. The results are also applicable to other models in which long-lived particles decay into multijet final states.« less

Search for R -parity violating supersymmetry with displaced vertices in proton-proton collisions at s = 8 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.

Results are reported from a search for R-parity violating supersymmetry in proton-proton collision events collected by the CMS experiment at a center-of-mass energy of √s = 8 TeV. Here, the data sample corresponds to an integrated luminosity of 17.6 fb –1. This search assumes a minimal flavor violating model in which the lightest supersymmetric particle is a long-lived neutralino or gluino, leading to a signal with jets emanating from displaced vertices. In a sample of events with two displaced vertices, no excess yield above the expectation from standard model processes is observed, and limits are placed on the pair productionmore » cross section as a function of mass and lifetime of the neutralino or gluino. At 95% confidence level, the analysis excludes cross sections above approximately 1 fb for neutralinos or gluinos with mass between 400 and 1500 GeV and mean proper decay length between 1 and 30 mm. Gluino masses are excluded below 1 and 1.3 TeV for mean proper decay lengths of 300 μm an 1 mm, respectively, and below 1.4 TeV for the range 2–30 mm. The results are also applicable to other models in which long-lived particles decay into multijet final states.« less

Predicting Displaceable Water Sites Using Mixed-Solvent Molecular Dynamics.

PubMed

Graham, Sarah E; Smith, Richard D; Carlson, Heather A

2018-02-26

Water molecules are an important factor in protein-ligand binding. Upon binding of a ligand with a protein's surface, waters can either be displaced by the ligand or may be conserved and possibly bridge interactions between the protein and ligand. Depending on the specific interactions made by the ligand, displacing waters can yield a gain in binding affinity. The extent to which binding affinity may increase is difficult to predict, as the favorable displacement of a water molecule is dependent on the site-specific interactions made by the water and the potential ligand. Several methods have been developed to predict the location of water sites on a protein's surface, but the majority of methods are not able to take into account both protein dynamics and the interactions made by specific functional groups. Mixed-solvent molecular dynamics (MixMD) is a cosolvent simulation technique that explicitly accounts for the interaction of both water and small molecule probes with a protein's surface, allowing for their direct competition. This method has previously been shown to identify both active and allosteric sites on a protein's surface. Using a test set of eight systems, we have developed a method using MixMD to identify conserved and displaceable water sites. Conserved sites can be determined by an occupancy-based metric to identify sites which are consistently occupied by water even in the presence of probe molecules. Conversely, displaceable water sites can be found by considering the sites which preferentially bind probe molecules. Furthermore, the inclusion of six probe types allows the MixMD method to predict which functional groups are capable of displacing which water sites. The MixMD method consistently identifies sites which are likely to be nondisplaceable and predicts the favorable displacement of water sites that are known to be displaced upon ligand binding.

Direct design of an energy landscape with bistable DNA origami mechanisms.

PubMed

Zhou, Lifeng; Marras, Alexander E; Su, Hai-Jun; Castro, Carlos E

2015-03-11

Structural DNA nanotechnology provides a feasible technique for the design and fabrication of complex geometries even exhibiting controllable dynamic behavior. Recently we have demonstrated the possibility of implementing macroscopic engineering design approaches to construct DNA origami mechanisms (DOM) with programmable motion and tunable flexibility. Here, we implement the design of compliant DNA origami mechanisms to extend from prescribing motion to prescribing an energy landscape. Compliant mechanisms facilitate motion via deformation of components with tunable stiffness resulting in well-defined mechanical energy stored in the structure. We design, fabricate, and characterize a DNA origami nanostructure with an energy landscape defined by two stable states (local energy minima) separated by a designed energy barrier. This nanostructure is a four-bar bistable mechanism with two undeformed states. Traversing between those states requires deformation, and hence mechanical energy storage, in a compliant arm of the linkage. The energy barrier for switching between two states was obtained from the conformational distribution based on a Boltzmann probability function and closely follows a predictive mechanical model. Furthermore, we demonstrated the ability to actuate the mechanism into one stable state via additional DNA inputs and then release the actuation via DNA strand displacement. This controllable multistate system establishes a foundation for direct design of energy landscapes that regulate conformational dynamics similar to biomolecular complexes.

Fluidic Energy Harvester Optimization in Grid Turbulence

NASA Astrophysics Data System (ADS)

Danesh-Yazdi, Amir; Elvin, Niell; Andreopoulos, Yiannis

2017-11-01

Even though it is omnipresent in nature, there has not been a great deal of research in the literature involving turbulence as an energy source for piezoelectric fluidic harvesters. In the present work, a grid-generated turbulence forcing function model which we derived previously is employed in the single degree-of-freedom electromechanical equations to find the power output and tip displacement of piezoelectric cantilever beams. Additionally, we utilize simplified, deterministic models of the turbulence forcing function to obtain closed-form expressions for the power output. These theoretical models are studied using experiments that involve separately placing a hot-wire anemometer probe and a short PVDF beam in flows where turbulence is generated by means of passive and semi-passive grids. From a parametric study on the deterministic models, we show that the white noise forcing function best mimics the experimental data. Furthermore, our parametric study of the response spectrum of a generic fluidic harvester in grid-generated turbulent flow shows that optimum power output is attained for beams placed closer to the grid with a low natural frequency and damping ratio and a large electromechanical coupling coefficient. NSF Grant No. CBET 1033117.

A Deep Analysis of Center Displacement in An Idealized Tropical Cyclone with Low-wavenumber Asymmetries

NASA Astrophysics Data System (ADS)

Zhao, C.; Song, J.; Leng, H.

2017-12-01

The Tropical Cyclone(TC) center-finding technique plays an important role when diagnostic analyses of TC structure are performed, especially when dealing with low-wavenumber asymmetries. Previous works have already established that structure of TCs can vary greatly depending on the displacement induced by center-finding techniques. As it is difficult to define a true TC center in the real world, this work seeks to explore how low-wavenumber azimuthal Fourier analyses can vary with center displacement using idealized, parametric TC-like vortices with different perturbation structures. It is shown that the errors is sensitive to the location and radial structure of the adding perturbation. In the case of adding azimuthal wavenumber 1 and 3 asymmetries, the increasing radial shear of initial asymmetries will enhance the corresponding spectral energy around radius of maximum wind(RMW) significantly, and they also have a great effect on spectral energy of wavenumber 2. On the contrary, the wavenumber 2 cases show a reduction from 1RMW to outer radius when shear is increasing and has little effect on spectral energy of wavenumber 1 or 2. Pervious findings indicated that the aliasing is dependent on the placement of center relative to the location of the asymmetries, which is also valid in these shearing situations. Moreover, it is found that this aliasing caused by phase displacement is less sensitive with the radial shear in wavenumber 2 and 3 cases, while it shows an significant amplification and deformation when wavenumber 1 asymmetry is added.

Toehold-Mediated Displacement of an Adenosine-Binding Aptamer from a DNA Duplex by its Ligand.

PubMed

Monserud, Jon H; Macri, Katherine M; Schwartz, Daniel K

2016-10-24

DNA is increasingly used to engineer dynamic nanoscale circuits, structures, and motors, many of which rely on DNA strand-displacement reactions. The use of functional DNA sequences (e.g., aptamers, which bind to a wide range of ligands) in these reactions would potentially confer responsiveness on such devices, and integrate DNA computation with highly varied molecular stimuli. By using high-throughput single-molecule FRET methods, we compared the kinetics of a putative aptamer-ligand and aptamer-complement strand-displacement reaction. We found that the ligands actively disrupted the DNA duplex in the presence of a DNA toehold in a similar manner to complementary DNA, with kinetic details specific to the aptamer structure, thus suggesting that the DNA strand-displacement concept can be extended to functional DNA-ligand systems. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular dynamics simulation of low-energy recoil events in titanate pyrochlores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Liyuan; Setyawan, Wahyu; Li, Yuhong

2017-01-01

Molecular dynamics simulations of low-energy displacements in titanate pyrochlores have been carried out along three main directions, to determineE dfor A, Ti and O, corresponding defect configurations, and defect formation dynamics.

Radiographic follow-up of 84 operatively treated scapula neck and body fractures.

PubMed

Cole, Peter A; Gauger, Erich M; Herrera, Diego A; Anavian, Jack; Tarkin, Ivan S

2012-03-01

Certain scapula fractures may warrant surgical management to restore shoulder anatomy and promote optimal function. The purpose of this study is to determine the early radiographic follow-up of open reduction internal fixation (ORIF) for displaced, scapular fractures involving the glenoid neck and body. Eighty-four patients with a scapula body or neck fracture (with or without articular involvement) underwent ORIF between 2002 and 2010 at a single level I trauma centre. This study represents a retrospective review of data prospectively collected into a dedicated scapula fracture database. All patients met at least one of the following operative criteria: ≥20 mm medial/lateral (M/L) displacement (lateral border offset), ≥45° of angular deformity on a scapular-Y X-ray, the combination of angulation ≥30° plus M/L displacement ≥15 mm, double disruptions of the superior shoulder suspensory complex both displaced ≥10 mm, glenopolar angle (GPA) ≤22° and open fractures. Eighty-eight percent (74/84) had sufficient follow-up defined as at least 6 months. Measured outcomes included rates of scapula union and malunion, as well as surgical complications and re-operations. All fractures were caused by high-energy trauma with 24 (29%) resulting from motor-vehicle collisions. Associated injuries occurred in 94% of patients, most commonly involving the chest (70%) and ipsilateral shoulder girdle (43%). Forty-eight patients had M/L displacement as an operative indication with a mean displacement of 25.7 mm (range=20-40). Thirty-eight (45%) had ≥2 operative indications. A single surgeon performed ORIF in all patients using a posterior approach. Five patients also required an anterior (deltopectoral) approach. The fixation strategy included lateral and vertebral border stabilisation with dynamic compression and reconstruction plates, respectively. Union was achieved in all cases. There were three cases of malunion based on a GPA difference >10° from the uninjured shoulder. Re-operations included removal of hardware (seven patients) and manipulation under anaesthesia (three patients). There were no infections or wound dehiscence. ORIF for displaced scapula fractures is a relatively safe and effective procedure for restoration of anatomy and promotion of union. Therapeutic study, level IV. Copyright © 2011 Elsevier Ltd. All rights reserved.

An overview of the value of parabolic dish solar thermal systems in industrial cogeneration applications

NASA Technical Reports Server (NTRS)

1982-01-01

The essential elements of the cogeneration system configuration to be captured were the displacement of thermal energy by collection and use of the Brayton exhaust stream, and the sale back to the utility of any electricity production in excess of on-site requirements. In contrast to simply dumping these energy flows, their use or sale obviously serves, by itself, to increase gross value of the solar thermal energy system. Net allowable cost of the parabolic dish modules may or may not be increased, however. A consideration is that the waste heat capture and delivery subsystems are not free. This study does not address the incremental cost of adding waste heat capture, transport, and conversion (to steam, if necessary). It does compute a value for the thermal energy thereby displaced. This value can serve as a first-round input to any detailed economic evaluation of waste heat recovery.

Atomistic Simulation of Displacement Cascades in Zircon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Devanathan, Ram; Weber, William J.; Corrales, Louis R.

2002-05-06

Low energy displacement cascades in zircon (ZrSiO4) initiated by a Zr primary knock-on atom have been investigated by molecular dynamics simulations using a Coulombic model for long-range interactions, Buckingham potential for short-range interactions and Ziegler-Biersack potentials for close pair interactions. Displacements were found to occur mainly in the O sublattice, and O replacements by a ring mechanism were predominant. Clusters containing Si interstitials bridged by O interstitials, vacancy clusters and anti-site defects were found to occur. This Si-O-Si bridging is considerable in quenched liquid ZrSiO4.

Fluorescence-excitation and emission spectra from LH2 antenna complexes of Rhodopseudomonas acidophila as a function of the sample preparation conditions.

PubMed

Kunz, Ralf; Timpmann, Kõu; Southall, June; Cogdell, Richard J; Köhler, Jürgen; Freiberg, Arvi

2013-10-10

The high sensitivity of optical spectra of pigment-protein complexes to temperature and pressure is well known. In the present study, we have demonstrated the significant influence of the environments commonly used in bulk and single-molecule spectroscopic studies at low temperatures on the LH2 photosynthetic antenna complex from Rhodopseudomonas acidophila. A transfer of this LH2 complex from a bulk-buffer solution into a spin-coated polymer film results in a 189 cm(-1) blue shift of the B850 excitonic absorption band at 5 K. Within the molecular exciton model, the origin of this shift could be disentangled into three parts, namely to an increase of the local site energies, a contraction of the exciton band, and a decrease of the displacement energy.

The Theory of Quantized Fields. III

DOE R&D Accomplishments Database

Schwinger, J.

1953-05-01

In this paper we discuss the electromagnetic field, as perturbed by a prescribed current. All quantities of physical interest in various situations, eigenvalues, eigenfunctions, and transformation probabilities, are derived from a general transformation function which is expressed in a non-Hermitian representation. The problems treated are: the determination of the energy-momentum eigenvalues and eigenfunctions for the isolated electromagnetic field, and the energy eigenvalues and eigenfunctions for the field perturbed by a time-independent current that departs from zero only within a finite time interval, and for a time-dependent current that assumes non-vanishing time-independent values initially and finally. The results are applied in a discussion of the intra-red catastrophe and of the adiabatic theorem. It is shown how the latter can be exploited to give a uniform formulation for all problems requiring the evaluation of transition probabilities or eigenvalue displacements.

Improvements in magnetic bearing performance for flywheel energy storage

NASA Technical Reports Server (NTRS)

Plant, David P.; Anand, Davinder K.; Kirk, James A.; Calomeris, Anthony J.; Romero, Robert L.

1988-01-01

The paper considers the development of a 500-Watt-hour magnetically suspended flywheel stack energy storage system. The work includes hardware testing results from a stack flywheel energy storage system, improvements in the area of noncontacting displacement transducers, and performance enhancements of magnetic bearings. Experimental results show that a stack flywheel energy storage system is feasible technology.

A method for determining electrophoretic and electroosmotic mobilities using AC and DC electric field particle displacements.

PubMed

Oddy, M H; Santiago, J G

2004-01-01

We have developed a method for measuring the electrophoretic mobility of submicrometer, fluorescently labeled particles and the electroosmotic mobility of a microchannel. We derive explicit expressions for the unknown electrophoretic and the electroosmotic mobilities as a function of particle displacements resulting from alternating current (AC) and direct current (DC) applied electric fields. Images of particle displacements are captured using an epifluorescent microscope and a CCD camera. A custom image-processing code was developed to determine image streak lengths associated with AC measurements, and a custom particle tracking velocimetry (PTV) code was devised to determine DC particle displacements. Statistical analysis was applied to relate mobility estimates to measured particle displacement distributions.

Stress-intensity factors and crack-opening displacements for round compact specimens. [fracture toughness of metallic materials

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.

1979-01-01

A two dimensional, boundary collocation stress analysis was used to analyze various round compact specimens. The influence of the round external boundary and of pin-loaded holes on stress intensity factors and crack opening displacements was determined as a function of crack-length-to-specimen-width ratios. A wide-range equation for the stress intensity factors was developed. Equations for crack-surface displacements and load-point displacements were also developed. In addition, stress intensity factors were calculated from compliance methods to demonstrate that load-displacement records must be made at the loading points and not along the crack line for crack-length-to-specimen-width ratios less than about 0.4.

[Conservative treatment of metacarpal fracture].

PubMed

Prokop, A; Helling, H J; Kulus, S; Rehm, K E

2002-01-01

Conservative treatment of meatacarpale fracture is recommended if there are no joint displacement, rotation failures, displacement over 30 degrees ad axim and shortening over 5 mm. Operative procedures should be done in open fractures and serial of fractures of metacarpale bones. Early functionally treatment should be done in stable, not displaced fractures. Cast can be used only for a short time in full extended position of fingers and flexion in metacarpo-phalangeal joint in 60-90 degrees. Twin-tapes after reduction of edema allowed free range of motion by fixed rotation. Closed reduction of displaced fractures of fifth metacarpal bone (boxer's fracture) isn't successful. Cases with displacement over 30 degrees may be operatively treated by intramedullary stabilization.

Effects of Displacement in Children Exposed to Disasters.

PubMed

Pfefferbaum, Betty; Jacobs, Anne K; Van Horn, Richard L; Houston, J Brian

2016-08-01

The literature on children's responses to disasters is well developed with increasing attention to the confounding experiences of displacement. This paper presents an overview of the emotional and behavioral effects of displacement on children and adolescents and describes their educational adjustment in terms of both academic achievement and school behavior. A summary of family effects elucidates how children's functioning is influenced through the family system in which they are embedded. The psychosocial impact of displacement reflects the myriad social losses that children and their families may face. Information from this review of the current literature on the effects of displacement may inform the design and delivery of support and intervention services for children and families following disasters.

Displacement monitoring of switch track and its slab on a bridge of high speed railway by FBG

NASA Astrophysics Data System (ADS)

Li, Weilai; Li, He; Cheng, Jian; Huang, Xiaomei; Pan, Jianjun; Zhou, Ciming; Yang, Minghong

2011-05-01

In a 350km/h high speed railway line, there is a seamless switch with ballastless slabs built on a bridge. 54 Fiber Bragg Grating detecting cells are employed to monitor the displacement of track and slab. The cell is of extending function of measurement range, up to 50mm displacement, and is of good linearity. Protecting methods for cells and fiber are adopted to keep them surviving from the harsh conditions. The results show that in 75 days, the displacement of the track and sleeper slab was 8-9mm, and the displacement is of high correlation with daily environmental temperature change.

Start-up and control method and apparatus for resonant free piston Stirling engine

DOEpatents

Walsh, Michael M.

1984-01-01

A resonant free-piston Stirling engine having a new and improved start-up and control method and system. A displacer linear electrodynamic machine is provided having an armature secured to and movable with the displacer and having a stator supported by the Stirling engine housing in juxtaposition to the armature. A control excitation circuit is provided for electrically exciting the displacer linear electrodynamic machine with electrical excitation signals having substantially the same frequency as the desired frequency of operation of the Stirling engine. The excitation control circuit is designed so that it selectively and controllably causes the displacer electrodynamic machine to function either as a generator load to extract power from the displacer or the control circuit selectively can be operated to cause the displacer electrodynamic machine to operate as an electric drive motor to apply additional input power to the displacer in addition to the thermodynamic power feedback to the displacer whereby the displacer linear electrodynamic machine also is used in the electric drive motor mode as a means for initially starting the resonant free-piston Stirling engine.

Radiological and Functional Outcome of Displaced Colles’ Fracture Managed with Closed Reduction and Percutaneous Pinning: A Prospective Study

PubMed Central

Khatri, Kishor; Kharel, Krishna; Byanjankar, Subin; Sharma, Jay R; Shrestha, Rahul; Vaishya, Raju; Agarwal, Amit Kumar; Vijay, Vipul

2017-01-01

Background: Displaced Colles’ fractures are treated by manipulation and below elbow cast application. Malunion is a common complication, resulting in pain, mid-carpal instability, and post-traumatic arthritis. Fracture stabilization by percutaneous pinning is a simple, minimally invasive technique that helps prevent displacement of the fracture, thereby minimizing complications. This study aims to assess the amount of collapse after closed manipulation and percutaneous pinning with Kirschner wires (K-wires) and its correlation with the functional outcome of the wrist after union. Methods: A prospective study was conducted from May 2015 to May 2016 in a tertiary orthopedic center. Ninety patients (60 females, 30 males) with an average age of 54.93 years with Type II fractures underwent closed manipulation and percutaneous pinning with crossed K-wires as the primary procedure. Serial radiographs were taken to document the amount of collapse. The functional outcome was assessed using the Cooney Wrist Score. Results: At the final follow-up at six months, the collapse in the mean dorsal angle was 0.94 and mean ulnar variance was 0.51. Functionally, 48 patients (53.33%) had an excellent outcome, 36 patients (40%) had a good outcome, and six patients (6.67%) had a fair outcome. Conclusions: Displaced Colles’ fractures should be reduced and stabilized with percutaneous K-wires to achieve an excellent functional outcome. PMID:28191366

Radiological and Functional Outcome of Displaced Colles' Fracture Managed with Closed Reduction and Percutaneous Pinning: A Prospective Study.

PubMed

Panthi, Sagar; Khatri, Kishor; Kharel, Krishna; Byanjankar, Subin; Sharma, Jay R; Shrestha, Rahul; Vaishya, Raju; Agarwal, Amit Kumar; Vijay, Vipul

2017-01-06

Displaced Colles' fractures are treated by manipulation and below elbow cast application. Malunion is a common complication, resulting in pain, mid-carpal instability, and post-traumatic arthritis. Fracture stabilization by percutaneous pinning is a simple, minimally invasive technique that helps prevent displacement of the fracture, thereby minimizing complications. This study aims to assess the amount of collapse after closed manipulation and percutaneous pinning with Kirschner wires (K-wires) and its correlation with the functional outcome of the wrist after union. A prospective study was conducted from May 2015 to May 2016 in a tertiary orthopedic center. Ninety patients (60 females, 30 males) with an average age of 54.93 years with Type II fractures underwent closed manipulation and percutaneous pinning with crossed K-wires as the primary procedure. Serial radiographs were taken to document the amount of collapse. The functional outcome was assessed using the Cooney Wrist Score. At the final follow-up at six months, the collapse in the mean dorsal angle was 0.94 and mean ulnar variance was 0.51. Functionally, 48 patients (53.33%) had an excellent outcome, 36 patients (40%) had a good outcome, and six patients (6.67%) had a fair outcome. Displaced Colles' fractures should be reduced and stabilized with percutaneous K-wires to achieve an excellent functional outcome.

Quantum Jeffreys prior for displaced squeezed thermal states

NASA Astrophysics Data System (ADS)

Kwek, L. C.; Oh, C. H.; Wang, Xiang-Bin

1999-09-01

It is known that, by extending the equivalence of the Fisher information matrix to its quantum version, the Bures metric, the quantum Jeffreys prior can be determined from the volume element of the Bures metric. We compute the Bures metric for the displaced squeezed thermal state and analyse the quantum Jeffreys prior and its marginal probability distributions. To normalize the marginal probability density function, it is necessary to provide a range of values of the squeezing parameter or the inverse temperature. We find that if the range of the squeezing parameter is kept narrow, there are significant differences in the marginal probability density functions in terms of the squeezing parameters for the displaced and undisplaced situations. However, these differences disappear as the range increases. Furthermore, marginal probability density functions against temperature are very different in the two cases.

Application of displacement monitoring system on high temperature steam pipe

NASA Astrophysics Data System (ADS)

Ghaffar, M. H. A.; Husin, S.; Baek, J. E.

2017-10-01

High-energy piping systems of power plants such as Main Steam (MS) pipe or Hot Reheat (HR) pipe are operating at high temperature and high pressure at base and cyclic loads. In the event of transient condition, a pipe can be deflected dramatically and caused high stress in the pipe, yielding to failure of the piping system. Periodic monitoring and walk down can identify abnormalities but limitations exist in the standard walk down practice. This paper provides a study of pipe displacement monitoring on MS pipe of coal-fired power plant to continuously capture the pipe movement behaviour at different load using 3-Dimensional Displacement Measuring System (3DDMS). The displacement trending at Location 5 and 6 (north and south) demonstrated pipes displace less than 25% to that of design movement. It was determined from synchronisation analysis that Location 7 (north) and Location 8 (south) pipe actual movement difference has exceeded the design movement difference. Visual survey at specified locations with significant displacement trending reveals issues of hydraulic snubber and piping interferences. The study demonstrated that the displacement monitoring is able to capture pipe movement at all time and allows engineer to monitor pipe movement behaviour, aids in identifying issue early for remedy action.

Ultrasonic Attenuation in Normal and Superconducting Indium.

DTIC Science & Technology

1980-05-22

dimension x space coordinate, dislocation displacement dislocation displacement y space coordinate.1z space coordinate x ACKNOWLEDGMENTS The author...The driving force on the dislocation is given by: F=bO (2.7) In general, the dislocation displacement will be a function of three space coordinates...mm diameter, 50 Q impedance coaxial conductors 47 * made of stainless steel and teflon . The cavity button is soldered * directly to the rigid

In vivo relationship between pelvis motion and deep fascia displacement of the medial gastrocnemius: anatomical and functional implications.

PubMed

Cruz-Montecinos, Carlos; González Blanche, Alberto; López Sánchez, David; Cerda, Mauricio; Sanzana-Cuche, Rodolfo; Cuesta-Vargas, Antonio

2015-11-01

Different authors have modelled myofascial tissue connectivity over a distance using cadaveric models, but in vivo models are scarce. The aim of this study was to evaluate the relationship between pelvic motion and deep fascia displacement in the medial gastrocnemius (MG). Deep fascia displacement of the MG was evaluated through automatic tracking with an ultrasound. Angular variation of the pelvis was determined by 2D kinematic analysis. The average maximum fascia displacement and pelvic motion were 1.501 ± 0.78 mm and 6.55 ± 2.47 °, respectively. The result of a simple linear regression between fascia displacement and pelvic motion for three task executions by 17 individuals was r = 0.791 (P < 0.001). Moreover, hamstring flexibility was related to a lower anterior tilt of the pelvis (r = 0.544, P < 0.024) and a lower deep fascia displacement of the MG (r = 0.449, P < 0.042). These results support the concept of myofascial tissue connectivity over a distance in an in vivo model, reinforce the functional concept of force transmission through synergistic muscle groups, and grant new perspectives for the role of fasciae in restricting movement in remote zones. © 2015 Anatomical Society.

In vivo relationship between pelvis motion and deep fascia displacement of the medial gastrocnemius: anatomical and functional implications

PubMed Central

Cruz-Montecinos, Carlos; González Blanche, Alberto; López Sánchez, David; Cerda, Mauricio; Sanzana-Cuche, Rodolfo; Cuesta-Vargas, Antonio

2015-01-01

Different authors have modelled myofascial tissue connectivity over a distance using cadaveric models, but in vivo models are scarce. The aim of this study was to evaluate the relationship between pelvic motion and deep fascia displacement in the medial gastrocnemius (MG). Deep fascia displacement of the MG was evaluated through automatic tracking with an ultrasound. Angular variation of the pelvis was determined by 2D kinematic analysis. The average maximum fascia displacement and pelvic motion were 1.501 ± 0.78 mm and 6.55 ± 2.47 °, respectively. The result of a simple linear regression between fascia displacement and pelvic motion for three task executions by 17 individuals was r = 0.791 (P < 0.001). Moreover, hamstring flexibility was related to a lower anterior tilt of the pelvis (r = 0.544, P < 0.024) and a lower deep fascia displacement of the MG (r = 0.449, P < 0.042). These results support the concept of myofascial tissue connectivity over a distance in an in vivo model, reinforce the functional concept of force transmission through synergistic muscle groups, and grant new perspectives for the role of fasciae in restricting movement in remote zones. PMID:26467242

Neutron displacement cross-sections for tantalum and tungsten at energies up to 1 GeV

NASA Astrophysics Data System (ADS)

Broeders, C. H. M.; Konobeyev, A. Yu.; Villagrasa, C.

2005-06-01

The neutron displacement cross-section has been evaluated for tantalum and tungsten at energies from 10 -5 eV up to 1 GeV. The nuclear optical model, the intranuclear cascade model combined with the pre-equilibrium and evaporation models were used for the calculations. The number of defects produced by recoil atoms nuclei in materials was calculated by the Norgett, Robinson, Torrens model and by the approach combining calculations using the binary collision approximation model and the results of the molecular dynamics simulation. The numerical calculations were done using the NJOY code, the ECIS96 code, the MCNPX code and the IOTA code.

Ab initio molecular dynamics simulation of the effects of stacking faults on the radiation response of 3C-SiC

PubMed Central

Jiang, M.; Peng, S. M.; Zhang, H. B.; Xu, C. H.; Xiao, H. Y.; Zhao, F. A.; Liu, Z. J.; Zu, X. T.

2016-01-01

In this study, an ab initio molecular dynamics method is employed to investigate how the existence of stacking faults (SFs) influences the response of SiC to low energy irradiation. It reveals that the C and Si atoms around the SFs are generally more difficult to be displaced than those in unfaulted SiC, and the corresponding threshold displacement energies for them are generally larger, indicative of enhanced radiation tolerance caused by the introduction of SFs, which agrees well with the recent experiment. As compared with the unfaulted state, more localized point defects are generated in faulted SiC. Also, the efficiency of damage production for Si recoils is generally higher than that of C recoils. The calculated potential energy increases for defect generation in SiC with intrinsic and extrinsic SFs are found to be higher than those in unfaulted SiC, due to the stronger screen-Coulomb interaction between the PKA and its neighbors. The presented results provide a fundamental insight into the underlying mechanism of displacement events in faulted SiC and will help to advance the understanding of the radiation response of SiC with and without SFs. PMID:26880027

A simple method for determining stress intensity factors for a crack in bi-material interface

NASA Astrophysics Data System (ADS)

Morioka, Yuta

Because of violently oscillating nature of stress and displacement fields near the crack tip, it is difficult to obtain stress intensity factors for a crack between two dis-similar media. For a crack in a homogeneous medium, it is a common practice to find stress intensity factors through strain energy release rates. However, individual strain energy release rates do not exist for bi-material interface crack. Hence it is necessary to find alternative methods to evaluate stress intensity factors. Several methods have been proposed in the past. However they involve mathematical complexity and sometimes require additional finite element analysis. The purpose of this research is to develop a simple method to find stress intensity factors in bi-material interface cracks. A finite element based projection method is proposed in the research. It is shown that the projection method yields very accurate stress intensity factors for a crack in isotropic and anisotropic bi-material interfaces. The projection method is also compared to displacement ratio method and energy method proposed by other authors. Through comparison it is found that projection method is much simpler to apply with its accuracy comparable to that of displacement ratio method.

Biologically inspired highly efficient buoyancy engine

NASA Astrophysics Data System (ADS)

Akle, Barbar; Habchi, Wassim; Abdelnour, Rita; Blottman, John, III; Leo, Donald

2012-04-01

Undersea distributed networked sensor systems require a miniaturization of platforms and a means of both spatial and temporal persistence. One aspect of this system is the necessity to modulate sensor depth for optimal positioning and station-keeping. Current approaches involve pneumatic bladders or electrolysis; both require mechanical subsystems and consume significant power. These are not suitable for the miniaturization of sensor platforms. Presented in this study is a novel biologically inspired method that relies on ionic motion and osmotic pressures to displace a volume of water from the ocean into and out of the proposed buoyancy engine. At a constant device volume, the displaced water will alter buoyancy leading to either sinking or floating. The engine is composed of an enclosure sided on the ocean's end by a Nafion ionomer and by a flexible membrane separating the water from a gas enclosure. Two electrodes are placed one inside the enclosure and the other attached to the engine on the outside. The semi-permeable membrane Nafion allows water motion in and out of the enclosure while blocking anions from being transferred. The two electrodes generate local concentration changes of ions upon the application of an electrical field; these changes lead to osmotic pressures and hence the transfer of water through the semi-permeable membrane. Some aquatic organisms such as pelagic crustacean perform this buoyancy control using an exchange of ions through their tissue to modulate its density relative to the ambient sea water. In this paper, the authors provide an experimental proof of concept of this buoyancy engine. The efficiency of changing the engine's buoyancy is calculated and optimized as a function of electrode surface area. For example electrodes made of a 3mm diameter Ag/AgCl proved to transfer approximately 4mm3 of water consuming 4 Joules of electrical energy. The speed of displacement is optimized as a function of the surface area of the Nafion membrane and its thickness. The 4mm3 displaced volume obtained with the Ag/AgCl electrodes required approximately 380 seconds. The thickness of the Nafion membrane is 180μm and it has an area of 133mm3.

Implementing displacement damage calculations for electrons and gamma rays in the Particle and Heavy-Ion Transport code System

NASA Astrophysics Data System (ADS)

Iwamoto, Yosuke

2018-03-01

In this study, the Monte Carlo displacement damage calculation method in the Particle and Heavy-Ion Transport code System (PHITS) was improved to calculate displacements per atom (DPA) values due to irradiation by electrons (or positrons) and gamma rays. For the damage due to electrons and gamma rays, PHITS simulates electromagnetic cascades using the Electron Gamma Shower version 5 (EGS5) algorithm and calculates DPA values using the recoil energies and the McKinley-Feshbach cross section. A comparison of DPA values calculated by PHITS and the Monte Carlo assisted Classical Method (MCCM) reveals that they were in good agreement for gamma-ray irradiations of silicon and iron at energies that were less than 10 MeV. Above 10 MeV, PHITS can calculate DPA values not only for electrons but also for charged particles produced by photonuclear reactions. In DPA depth distributions under electron and gamma-ray irradiations, build-up effects can be observed near the target's surface. For irradiation of 90-cm-thick carbon by protons with energies of more than 30 GeV, the ratio of the secondary electron DPA values to the total DPA values is more than 10% and increases with an increase in incident energy. In summary, PHITS can calculate DPA values for all particles and materials over a wide energy range between 1 keV and 1 TeV for electrons, gamma rays, and charged particles and between 10-5 eV and 1 TeV for neutrons.

Low energy ion-solid interactions and chemistry effects in a series of pyrochlores

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Liyuan; Li, Yuhong; Devanathan, Ram

The effect of chemistry on low energy recoil events was investigated at 10 K for each type of atom in pyrochlores using molecular dynamics simulation. Contour plots of the threshold displacement energy (Ed) in Gd2Zr2O7 have been produced along more than 80 directions for each individual species. The Ed surface for each type of atom in Gd2Zr2O7 is highly anisotropic; Ed of Zr exhibits the largest degree of anisotropy, while that of O8b exhibits the smallest. The recommended values of Ed in Gd2Zr2O7 based on the observed minima are 56, 94 and 25 eV, respectively for Gd, Zr and O.more » The influence of cation radius on Ed in pyrochlores A2B2O7 (with A-site ranging from Lu3+ to La3+ and B-site ranging from Ti4+ to Ce4+) was also investigated along three directions [100], [110] and [111]. The Ed in pyrochlores strongly depended on the atom type, atom mass, knock-on direction, and lattice position. The defects produced after low energy displacement events included cation antisite defects, cation Frenkel pairs, anion Frenkel pairs, various vacancies and interstitials. Ce doping in pyrochlores may affect the radiation response, because it resulted in drastic changes in cation and anion displacement energies and formation of an unusual type of anti-site defect. This work demonstrates links between Ed and amorphization resistance.« less

Radiological study of the secondary reduction effect of early functional exercise on displaced intra-articular calcaneal fractures after internal compression fixation.

PubMed

Chen, Wei; Liu, Bo; Lv, Hongzhi; Su, Yanling; Chen, Xiao; Zhu, Yanbin; Du, Chenguang; Zhang, Xiaolin; Zhang, Yingze

2017-09-01

Early post-operative exercise and weight-bearing activities are found to improve the functional recovery of patients with displaced intra-articular calcaneal fractures (DIACFs). We hypothesized that early functional exercise after surgery might have a secondary reduction effect on the subtalar joint, in particular the smaller fracture fragments that were not fixed firmly. A prospective study was conducted to verify this hypothesis. From December 2012 to September 2013, patients with unilateral DIACFs were enrolled and received a treatment consisting of percutaneous leverage and minimally invasive fixation. After surgery, patients in the study group started exercising on days two to three, using partial weight bearing starting week three, and full weight bearing starting week 12. Patients in the control group followed a conventional post-operative protocol of partial weight bearing after week six and full weight bearing after the bone healed. Computed tomography (CT) scanning was performed at post-operative day one, week four, week eight, and week 12 to reconstruct coronal, sagittal, and axial images, on which the maximal residual displacements of the fractures were measured. Function was evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) scoring scale at the 12th post-operative month. Twenty-eight patients in the study group and 32 in the control group were followed up for more than 12 months; their data were collected and used for the final analysis. Repeated-measures analysis of variance (ANOVA) of the maximal residual displacements of the fracture measured on CT images revealed significant differences between the study and the control groups. There were interaction effects between group and time point. Except for the first time point, the differences between the groups at all studied time points were significant. In the study group, the differences between all studied time points were significant. Strong correlations were observed between the AOFAS score at post-operative month 12 and the maximal residual displacement of the fractures on the CT images at postoperative week 12. Early functional exercise and weight bearing activity can smooth and shape the subtalar joint and reduce the residual displacement of the articular surface, improving functional recovery of the affected foot. Therefore, early rehabilitation functional exercise can be recommended in clinical practice.

Reconstructing particle masses in events with displaced vertices

NASA Astrophysics Data System (ADS)

Cottin, Giovanna

2018-03-01

We propose a simple way to extract particle masses given a displaced vertex signature in event topologies where two long-lived mother particles decay to visible particles and an invisible daughter. The mother could be either charged or neutral and the neutral daughter could correspond to a dark matter particle in different models. The method allows to extract the parent and daughter masses by using on-shell conditions and energy-momentum conservation, in addition to the displaced decay positions of the parents, which allows to solve the kinematic equations fully on an event-by-event basis. We show the validity of the method by means of simulations including detector effects. If displaced events are seen in discovery searches at the Large Hadron Collider (LHC), this technique can be applied.

Ab initio molecular dynamics simulations of AlN responding to low energy particle radiation

DOE PAGES

Xi, Jianqi; Liu, Bin; Zhang, Yanwen; ...

2018-01-30

Ab initio molecular dynamics simulations of low energy recoil events in wurtzite AlN have been performed to determine threshold displacement energies, defect production and evolution mechanisms, role of partial charge transfer during the process, and the influence of irradiation-induced defects on the properties of AlN. Here, the results show that the threshold displacement energies, E d, along the direction parallel to the basal planes are smaller than those perpendicular to the basal planes. The minimum E d values are determined to be 19 eV and 55 eV for N and Al atom, respectively, which occur along the [more » $$\\overline{11}20$$] direction. In general, the threshold displacement energies for N are smaller than those for Al atom, indicating the N defects would be dominant under irradiation. The defect production mechanisms have been analyzed. It is found that charge transfer and redistribution for both the primary knock-on atom and the subsequent recoil atoms play a significant role in defect production and evolution. Similar to the trend in oxide materials, there is a nearly linear relationship between E d and the total amount of charge transfer at the potential energy peak in AlN, which provides guidance on the development of charge-transfer interatomic potentials for classic molecular dynamics simulations. Finally, the response behavior of AlN to low energy irradiation is qualitatively investigated. The existence of irradiation-induced defects significantly modifies the electronic structure, and thus affects the magnetic, electronic and optical properties of AlN. In conclusion, these findings further enrich the understanding of defects in the wide bandgap semiconductor of AlN.« less

Ab initio molecular dynamics simulations of AlN responding to low energy particle radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xi, Jianqi; Liu, Bin; Zhang, Yanwen

Ab initio molecular dynamics simulations of low energy recoil events in wurtzite AlN have been performed to determine threshold displacement energies, defect production and evolution mechanisms, role of partial charge transfer during the process, and the influence of irradiation-induced defects on the properties of AlN. Here, the results show that the threshold displacement energies, E d, along the direction parallel to the basal planes are smaller than those perpendicular to the basal planes. The minimum E d values are determined to be 19 eV and 55 eV for N and Al atom, respectively, which occur along the [more » $$\\overline{11}20$$] direction. In general, the threshold displacement energies for N are smaller than those for Al atom, indicating the N defects would be dominant under irradiation. The defect production mechanisms have been analyzed. It is found that charge transfer and redistribution for both the primary knock-on atom and the subsequent recoil atoms play a significant role in defect production and evolution. Similar to the trend in oxide materials, there is a nearly linear relationship between E d and the total amount of charge transfer at the potential energy peak in AlN, which provides guidance on the development of charge-transfer interatomic potentials for classic molecular dynamics simulations. Finally, the response behavior of AlN to low energy irradiation is qualitatively investigated. The existence of irradiation-induced defects significantly modifies the electronic structure, and thus affects the magnetic, electronic and optical properties of AlN. In conclusion, these findings further enrich the understanding of defects in the wide bandgap semiconductor of AlN.« less

Design and Realization of a Three Degrees of Freedom Displacement Measurement System Composed of Hall Sensors Based on Magnetic Field Fitting by an Elliptic Function

PubMed Central

Zhao, Bo; Wang, Lei; Tan, Jiu-Bin

2015-01-01

This paper presents the design and realization of a three degrees of freedom (DOFs) displacement measurement system composed of Hall sensors, which is built for the XYθz displacement measurement of the short stroke stage of the reticle stage of lithography. The measurement system consists of three pairs of permanent magnets mounted on the same plane on the short stroke stage along the Y, Y, X directions, and three single axis Hall sensors correspondingly mounted on the frame of the reticle stage. The emphasis is placed on the decoupling and magnetic field fitting of the three DOFs measurement system. The model of the measurement system is illustrated, and the XY positions and θZ rotation of the short stroke stage can be obtained by decoupling the sensor outputs. A magnetic field fitting by an elliptic function-based compensation method is proposed. The practical field intensity of a permanent magnet at a certain plane height can be substituted for the output voltage of a Hall sensors, which can be expressed by the elliptic function through experimental data as the crucial issue to calculate the three DOFs displacement. Experimental results of the Hall sensor displacement measurement system are presented to validate the proposed three DOFs measurement system. PMID:26370993

Investigating a continuous shear strain function for depth-dependent properties of native and tissue engineering cartilage using pixel-size data.

PubMed

Motavalli, Mostafa; Whitney, G Adam; Dennis, James E; Mansour, Joseph M

2013-12-01

A previously developed novel imaging technique for determining the depth dependent properties of cartilage in simple shear is implemented. Shear displacement is determined from images of deformed lines photobleached on a sample, and shear strain is obtained from the derivative of the displacement. We investigated the feasibility of an alternative systematic approach to numerical differentiation for computing the shear strain that is based on fitting a continuous function to the shear displacement. Three models for a continuous shear displacement function are evaluated: polynomials, cubic splines, and non-parametric locally weighted scatter plot curves. Four independent approaches are then applied to identify the best-fit model and the accuracy of the first derivative. One approach is based on the Akaiki Information Criteria, and the Bayesian Information Criteria. The second is based on a method developed to smooth and differentiate digitized data from human motion. The third method is based on photobleaching a predefined circular area with a specific radius. Finally, we integrate the shear strain and compare it with the total shear deflection of the sample measured experimentally. Results show that 6th and 7th order polynomials are the best models for the shear displacement and its first derivative. In addition, failure of tissue-engineered cartilage, consistent with previous results, demonstrates the qualitative value of this imaging approach. © 2013 Elsevier Ltd. All rights reserved.

Structural and functional roles of a conserved proline residue in the alpha2 helix of Escherichia coli thioredoxin.

PubMed

de Lamotte-Guéry, F; Pruvost, C; Minard, P; Delsuc, M A; Miginiac-Maslow, M; Schmitter, J M; Stein, M; Decottignies, P

1997-12-01

Proline 40 in Escherichia coli thioredoxin is located close to the redox active site (Cys32-Cys35) within the alpha2 helix. The conservation of this residue among most of the thioredoxins suggests that it could play an important role in the structure and/or function of this protein. We have substituted Pro40 for Ala by using site-directed mutagenesis and expressed the mutant P40A in E.coli. The effects of the mutation on the biophysical and biological properties of thioredoxin have been analyzed and compared with molecular dynamics simulations. Modeling predicted that the replacement of Pro40 by Ala induced a displacement of the active site which exposes Trp31 to the solvent and opens a cleft located between helices alpha2 and alpha3. The solvation free energy (SFE) calculation also indicated that P40A became more hydrophobic as W31 became more accessible. These predictions were totally in agreement with the experimental results. The mutant P40A exhibited chromatographic behavior and fluorescence properties very different from those of the wild-type (WT) protein, in relationship with the displacement of W31. The determination of the free energy of unfolding of P40A showed that the mutant was globally destabilized by 2.9 kcal/mol. However, the effect of the mutation on the transition curve was highly unusual as the midpoint of the unfolding transition increased, indicating that some local structures were actually stabilized by the mutation. Despite these structural modifications, neither the ability of the protein to reduce a chloroplastic enzyme nor its reactivity with the bacterial reductase decreased. The only functional difference was the higher stability of P40A in light activation of NADP-malate dehydrogenase under air, which suggests that the mutant was less rapidly re-oxidized than WT. Therefore, it can be concluded that Pro40 is not essential for maintaining the redox function of thioredoxin but rather is required for the stability of the protein.

Studies of O18 impurity trapping at interstitial dislocation loops in ion implanted Fe (1 1 0) by ion channeling and ab initio calculations

NASA Astrophysics Data System (ADS)

Mathayan, Vairavel; Kothalamuthu, Saravanan; Gnanasekaran, Jaiganesh; Balakrishnan, Sundaravel; Panigrahi, Binaykumar

2018-01-01

The O18 and self ions are implanted at same depth in Fe (1 1 0) crystal and annealed to study the oxygen trapping under excess self interstitial defects. Rutherford backscattering spectrometry, nuclear reaction analysis and channeling measurements have been performed to determine the lattice site position of O18. The presence of dislocation loops is confirmed by energy-dependent dechanneling parameter measurements. From the tilt angular scans of Fe and O18 signals along 〈1 0 0〉, 〈1 1 0〉 axes, O18 is found to be displaced 0.2 Å from tetrahedral towards octahedral interstitial site in O18. Similar lattice site location of oxygen with the displacement of 0.37 Å is predicted by density functional theory calculations for the interaction of oxygen with 〈1 0 0〉 interstitial dislocation loop structure. Our results provide strong evidence on oxygen trapping at interstitial dislocation loops in the presence of excess interstitial defects in iron.

Modeling of a viscoelastic damper and its application in structural control.

PubMed

Mehrabi, M H; Suhatril, Meldi; Ibrahim, Zainah; Ghodsi, S S; Khatibi, Hamed

2017-01-01

Conventional seismic rehabilitation methods may not be suitable for some buildings owing to their high cost and time-consuming foundation work. In recent years, viscoelastic dampers (VEDs) have been widely used in many mid- and high-rise buildings. This study introduces a viscoelastic passive control system called rotary rubber braced damper (RRBD). The RRBD is an economical, lightweight, and easy-to-assemble device. A finite element model considering nonlinearity, large deformation, and material damage is developed to conduct a parametric study on different damper sizes under pushover cyclic loading. The fundamental characteristics of this VED system are clarified by analyzing building structures under cyclic loading. The result show excellent energy absorption and stable hysteresis loops in all specimens. Additionally, by using a sinusoidal shaking table test, the effectiveness of the RRBD to manage the response displacement and acceleration of steel frames is considered. The RRBD functioned at early stages of lateral displacement, indicating that the system is effective for all levels of vibration. Moreover, the proposed damper shows significantly better performance in terms of the column compression force resulting from the brace action compared to chevron bracing (CB).

Fluorescence Resonance Energy Transfer-Based Photonic Circuits Using Single-Stranded Tile Self-Assembly and DNA Strand Displacement.

PubMed

Zhang, Xuncai; Ying, Niu; Shen, Chaonan; Cui, Guangzhao

2017-02-01

Structural DNA nanotechnology has great potential in the fabrication of complicated nanostructures and devices capable of bio-sensing and logic function. A variety of nanostructures with desired shapes have been created in the past few decades. But the application of nanostructures remains to be fully studied. Here, we present a novel biological information processing system constructed on a self-assembled, spatially addressable single-stranded tile (SST) nanostructure as DNA nano-manipulation platform that created by SST self-assembly technology. Utilizing DNA strand displacement technology, the fluorescent dye that is pre-assembled in the nano-manipulation platform is transferred from the original position to the destination, which can achieve photonic logic circuits by FRET signal cascades, including logic AND, OR, and NOT gates. And this transfer process is successfully validated by visual DSD software. The transfer process proposed in this study may provide a novel method to design complicated biological information processing system constructed on a SST nanostructure, and can be further used to develop intelligent delivery of drug molecules in vivo.

Dynamic state of water molecular displacement of the brain during the cardiac cycle in idiopathic normal pressure hydrocephalus.

PubMed

Kan, Hirohito; Miyati, Tosiaki; Mase, Mitsuhito; Osawa, Tomoshi; Ohno, Naoki; Kasai, Harumasa; Arai, Nobuyuki; Kawano, Makoto; Shibamoto, Yuta

2015-03-01

The predictive accuracy of iNPH diagnoses could be increased using a combination of supplemental tests for iNPH. To evaluate the dynamic state of water displacement during the cardiac cycle in idiopathic normal pressure hydrocephalus (iNPH), we determined the change in water displacement using q-space analysis of diffusion magnetic resonance image. ECG-triggered single-shot diffusion echo planar imaging was used. Water displacement was obtained from the displacement probability profile calculated by Fourier transform of the signal decay fitted as a function of the reciprocal spatial vector q. Then maximum minus minimum displacement (delta-displacement), of all cardiac phase images was calculated. We assessed the delta-displacement in white matter in patients with iNPH and atrophic ventricular dilation (atrophic VD), and in healthy volunteers (control group). Delta-displacement in iNPH was significantly higher than those in the atrophic VD and control. This shows that water molecules of the white matter in iNPH are easily fluctuated by volume loading of the cranium during the cardiac cycle, due to the decrease in intracranial compliance. There was no significant correlation between delta-displacement and displacement. The delta-displacement and the displacement do not necessarily yield the same kind of information. Delta-displacement demonstrated to obtain biophysical information about fluctuation. This analysis may be helpful in the understanding physiology and pathological condition in iNPH and the assisting in the diagnosis. Copyright © 2015 Elsevier Ltd. All rights reserved.

The energetics of heterogeneous deformation in open-cell elastic foams

NASA Astrophysics Data System (ADS)

Gioia, Gustavo; Cuitino, Alberto

2002-03-01

We study the energetics of a model of elastic foams to show that the stretch heterogeneity observed in experiments stems from the lack of convexity of the governing energy functional. The predicted stretch distributions correspond to stratified mixtures of two configurational phases of the foam. Stretching occurs in the form of a phase transition, by growth of one of the phases at the expense of the other. We also compare the predicted mechanical response with experimental data for foams of different densities. Lastly, we perform displacement field measurements using the digital image correlation technique, and find the results to be in agreement with our predictions.

Thermo-Elastic Triangular Sandwich Element for the Complete Stress Field Based on a Single-Layer Theory

NASA Technical Reports Server (NTRS)

Das, M.; Barut, A.; Madenci, E.; Ambur, D. R.

2004-01-01

This study presents a new triangular finite element for modeling thick sandwich panels, subjected to thermo-mechanical loading, based on a {3,2}-order single-layer plate theory. A hybrid energy functional is employed in the derivation of the element because of a C interelement continuity requirement. The single-layer theory is based on five weighted-average field variables arising from the cubic and quadratic representations of the in-plane and transverse displacement fields, respectively. The variations of temperature and distributed loading acting on the top and bottom surfaces are non-uniform. The temperature varies linearly through the thickness.

Data Report. Volume I. Velocity and Temperature Profile Data for Zero Pressure Gradient, Fully Turbulent Boundary Layers.

DTIC Science & Technology

1981-01-01

Werle I DAft’Janu’_Lt 8 5 NO. OF PAGES 326 COPY NO. ____ 3AIR T𔃺r12 Or tC OF CIDWIMZ RUR (47SC) NO nifE OF TPRANSMTTL TO DDC T17J2 ! nch:ical report...integral properties are determined B W) displacement thickness y dy o Pe Ue (ii) momentum thickness f( dy 0 PC Ue (iii) energy-dissipation thickness a~ 0...NO. I BOUNDARY LAYER PROPERTIES STANDARD LINEAR SUBLAYER INTERPOLATION FUNCTION FROM TO WALL WALL TO Y*=35 FREE STREAM VELOCITY = 98,579 98.579 FREE

Prediction of phonon-mediated superconductivity in hole-doped black phosphorus.

PubMed

Feng, Yanqing; Sun, Hongyi; Sun, Junhui; Lu, Zhibin; You, Yong

2018-01-10

We study the conventional electron-phonon mediated superconducting properties of hole-doped black phosphorus by density functional calculations and get quite a large electron-phonon coupling (EPC) constant λ ~ 1.0 with transition temperature T C ~ 10 K, which is comparable to MgB 2 when holes are doped into the degenerate and nearly flat energy bands around the Fermi level. We predict that the softening of low-frequency [Formula: see text] optical mode and its phonon displacement, which breaks the lattice nonsymmorphic symmetry of gliding plane and lifts the band double degeneracy, lead to a large EPC. These factors are favorable for BCS superconductivity.

Prediction of phonon-mediated superconductivity in hole-doped black phosphorus

NASA Astrophysics Data System (ADS)

Feng, Yanqing; Sun, Hongyi; Sun, Junhui; Lu, Zhibin; You, Yong

2018-01-01

We study the conventional electron-phonon mediated superconducting properties of hole-doped black phosphorus by density functional calculations and get quite a large electron-phonon coupling (EPC) constant λ ~ 1.0 with transition temperature T C ~ 10 K, which is comparable to MgB2 when holes are doped into the degenerate and nearly flat energy bands around the Fermi level. We predict that the softening of low-frequency B3g1 optical mode and its phonon displacement, which breaks the lattice nonsymmorphic symmetry of gliding plane and lifts the band double degeneracy, lead to a large EPC. These factors are favorable for BCS superconductivity.

Measurement of O and Ti atom displacements in TiO 2 during flash sintering experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Bola; Yadav, Devinder; Raj, Rishi

In-situ flash experiments on rutile TiO 2 were performed at the synchrotron at the Brookhaven National Laboratory. Pair distribution function analysis of total X-ray scattering measurements yielded mean-square atomic displacements of oxygen and titanium atoms during the progression of the 3 stages of flash. The displacements are measured to be far greater for oxygen atoms than for titanium atoms. Thus, these large displacements may signal an “elastic softening” of the lattice, which, recently, has been predicted as a precursor to the onset of flash.

Dynamic surface acoustic response to a thermal expansion source on an anisotropic half space.

PubMed

Zhao, Peng; Zhao, Ji-Cheng; Weaver, Richard

2013-05-01

The surface displacement response to a distributed thermal expansion source is solved using the reciprocity principle. By convolving the strain Green's function with the thermal stress field created by an ultrafast laser illumination, the complete surface displacement on an anisotropic half space induced by laser absorption is calculated in the time domain. This solution applies to the near field surface displacement due to pulse laser absorption. The solution is validated by performing ultrafast laser pump-probe measurements and showing very good agreement between the measured time-dependent probe beam deflection and the computed surface displacement.

Measurement of O and Ti atom displacements in TiO 2 during flash sintering experiments

DOE PAGES

Yoon, Bola; Yadav, Devinder; Raj, Rishi; ...

2017-12-29

In-situ flash experiments on rutile TiO 2 were performed at the synchrotron at the Brookhaven National Laboratory. Pair distribution function analysis of total X-ray scattering measurements yielded mean-square atomic displacements of oxygen and titanium atoms during the progression of the 3 stages of flash. The displacements are measured to be far greater for oxygen atoms than for titanium atoms. Thus, these large displacements may signal an “elastic softening” of the lattice, which, recently, has been predicted as a precursor to the onset of flash.

Multi-resonant electromagnetic shunt in base isolation for vibration damping and energy harvesting

NASA Astrophysics Data System (ADS)

Pei, Yalu; Liu, Yilun; Zuo, Lei

2018-06-01

This paper investigates multi-resonant electromagnetic shunts applied to base isolation for dual-function vibration damping and energy harvesting. Two multi-mode shunt circuit configurations, namely parallel and series, are proposed and optimized based on the H2 criteria. The root-mean-square (RMS) value of the relative displacement between the base and the primary structure is minimized. Practically, this will improve the safety of base-isolated buildings subjected the broad bandwidth ground acceleration. Case studies of a base-isolated building are conducted in both the frequency and time domains to investigate the effectiveness of multi-resonant electromagnetic shunts under recorded earthquake signals. It shows that both multi-mode shunt circuits outperform traditional single mode shunt circuits by suppressing the first and the second vibration modes simultaneously. Moreover, for the same stiffness ratio, the parallel shunt circuit is more effective at harvesting energy and suppressing vibration, and can more robustly handle parameter mistuning than the series shunt circuit. Furthermore, this paper discusses experimental validation of the effectiveness of multi-resonant electromagnetic shunts for vibration damping and energy harvesting on a scaled-down base isolation system.

Calculations of the displacement damage and short-circuit current degradation in proton irradiated (AlGa)As-GaAs solar cells

NASA Technical Reports Server (NTRS)

Yeh, C. S.; Li, S. S.; Loo, R. Y.

1987-01-01

A theoretical model for computing the displacement damage defect density and the short-circuit current (I sub sc) degradation in proton-irradiated (AlGa)As-GaAs p-n junction solar cells is presented. Assumptions were made with justification that the radiation induced displacement defects form an effective recombination center which controls the electron and hole lifetimes in the junction space charge region and in the n-GaAs active layer of the irradiated GaAs p-n junction cells. The degradation of I sub sc in the (AlGa)As layer was found to be negligible compared to the total degradation. In order to determine the I sub sc degradation, the displacement defect density, path length, range, reduced energy after penetrating a distance x, and the average number of displacements formed by one proton scattering event were first calculated. The I sub sc degradation was calculated by using the electron capture cross section in the p-diffused layer and the hole capture cross section in the n-base layer as well as the wavelength dependent absorption coefficients. Excellent agreement was found between the researchers calculated values and the measured I sub sc in the proton irradiated GaAs solar cells for proton energies of 100 KeV to 10 MeV and fluences from 10 to the 10th power p/square cm to 10 to the 12th power p/square cm.

Vibrational energy harvesting by exploring structural benefits and nonlinear characteristics

NASA Astrophysics Data System (ADS)

Wei, Chongfeng; Jing, Xingjian

2017-07-01

Traditional energy harvesters are often of low efficiency due to very limited energy harvesting bandwidth, which should also be enough close to the ambient excitation frequency. To overcome this difficulty, some attempts can be seen in the literature typically with the purposes of either increasing the energy harvesting bandwidth with a harvester array, or enhancing the energy harvesting bandwidth and peak with nonlinear coupling effect etc. This paper presents an alternative way which can achieve tuneable resonant frequency (from high frequency to ultralow frequency) and improved energy harvesting bandwidth and peak simultaneously by employing special structural benefits and advantageous displacement-dependent nonlinear damping property. The proposed energy harvesting system employs a lever systems combined with an X-shape supporting structure and demonstrates very adjustable stiffness and unique nonlinear damping characteristics which are very beneficial for energy harvesting. It is shown that the energy harvesting performance of the proposed system is directly determined by several easy-to-tune structural parameters and also by the relative displacement in a special nonlinear manner, which provides a great flexibility and/or a unique tool for tuning and improving energy harvesting efficiency via matching excitation frequencies and covering a broader frequency band. This study potentially provides a new insight into the design of energy harvesting systems by employing structural benefits and geometrical nonlinearities.

HOT WATER DISPLACEMENT FOR THE RECOVERY OF VISCOUS OIL

EPA Science Inventory

The relative permeability curves that have been calculated from the displacement data so far show changes in the relative permeabilities of oil and water with temperature. Currently, saturated hydraulic conductivity determinations are being made as function of temperature for th...

A numerical study on piezoelectric energy harvesting by combining transverse galloping and parametric instability phenomena

NASA Astrophysics Data System (ADS)

Franzini, Guilherme Rosa; Santos, Rebeca Caramêz Saraiva; Pesce, Celso Pupo

2017-12-01

This paper aims to numerically investigate the effects of parametric instability on piezoelectric energy harvesting from the transverse galloping of a square prism. A two degrees-of-freedom reduced-order model for this problem is proposed and numerically integrated. A usual quasi-steady galloping model is applied, where the transverse force coefficient is adopted as a cubic polynomial function with respect to the angle of attack. Time-histories of nondimensional prism displacement, electric voltage and power dissipated at both the dashpot and the electrical resistance are obtained as functions of the reduced velocity. Both, oscillation amplitude and electric voltage, increased with the reduced velocity for all parametric excitation conditions tested. For low values of reduced velocity, 2:1 parametric excitation enhances the electric voltage. On the other hand, for higher reduced velocities, a 1:1 parametric excitation (i.e., the same as the natural frequency) enhances both oscillation amplitude and electric voltage. It has been also found that, depending on the parametric excitation frequency, the harvested electrical power can be amplified in 70% when compared to the case under no parametric excitation.

Impact of implementation of spaceborne lidar-retrieved canopy height in the WRF model

NASA Astrophysics Data System (ADS)

Lee, Junhong; Hong, Jinkyu

2017-04-01

Canopy height is closely related to biomass and aerodynamic properties, which regulate turbulent transfer of energy and mass at the soil-vegetation-atmosphere continuum. However, this key information has been prescribed as a constant value in a fixed plant functional type in atmospheric models. This presentation reports impacts of using realistic forest canopy height, retrieved from spaceborne LiDAR, on regional climate simulation in the Weather Research and Forecasting (WRF) model's land surface model. Numerical simulations were conducted over the Amazon Basin and East Asia during summer season. Over these regions, the LiDAR-retrieved canopy heights were higher than the default values used in the WRF,which are dependent only on plant functional type. By modifying roughness length and zero-plane displacement height, the change of canopy height resulted in changes in surface energy balance by regulating aerodynamic conductances and vertical temperature gradient, thus modifying the lifting condensation level and equivalent potential temperature in the atmospheric boundary layer. Our analysis also showed that the WRF model better reproduced the observed precipitation when LiDAR-retrieved canopy height was used over the Amazon Basin.

Implementation of spaceborne lidar-retrieved canopy height in the WRF model

NASA Astrophysics Data System (ADS)

Lee, Junhong; Hong, Jinkyu

2016-06-01

Canopy height is closely related to biomass and aerodynamic properties, which regulate turbulent transfer of energy and mass at the soil-vegetation-atmosphere continuum. However, this key information has been prescribed as a constant value in a fixed plant functional type in atmospheric models. This paper is the first to report impacts of using realistic forest canopy height, retrieved from spaceborne lidar, on regional climate simulation by using the canopy height data in the Weather Research and Forecasting (WRF) model's land surface model. Numerical simulations were conducted over the Amazon Basin during summer season. Over this region, the lidar-retrieved canopy heights were higher than the default values used in the WRF, which are dependent only on plant functional type. By modifying roughness length and zero-plane displacement height, the change of canopy height resulted in changes in surface energy balance by regulating aerodynamic conductances and vertical temperature gradient, thus modifying the lifting condensation level and equivalent potential temperature in the atmospheric boundary layer. Our analysis also showed that the WRF model better reproduced the observed precipitation when lidar-retrieved canopy height was used over the Amazon Basin.

One-dimensional modeling of thermal energy produced in a seismic fault

NASA Astrophysics Data System (ADS)

Konga, Guy Pascal; Koumetio, Fidèle; Yemele, David; Olivier Djiogang, Francis

2017-12-01

Generally, one observes an anomaly of temperature before a big earthquake. In this paper, we established the expression of thermal energy produced by friction forces between the walls of a seismic fault while considering the dynamic of a one-dimensional spring-block model. It is noted that, before the rupture of a seismic fault, displacements are caused by microseisms. The curves of variation of this thermal energy with time show that, for oscillatory and aperiodic displacement, the thermal energy is accumulated in the same way. The study reveals that thermal energy as well as temperature increases abruptly after a certain amount of time. We suggest that the corresponding time is the start of the anomaly of temperature observed which can be considered as precursory effect of a big seism. We suggest that the thermal energy can heat gases and dilate rocks until they crack. The warm gases can then pass through the cracks towards the surface. The cracks created by thermal energy can also contribute to the rupture of the seismic fault. We also suggest that the theoretical model of thermal energy, produced in seismic fault, associated with a large quantity of experimental data may help in the prediction of earthquakes.

Modeling the elastic energy of alloys: Potential pitfalls of continuum treatments.

PubMed

Baskaran, Arvind; Ratsch, Christian; Smereka, Peter

2015-12-01

Some issues that arise when modeling elastic energy for binary alloys are discussed within the context of a Keating model and density-functional calculations. The Keating model is a simplified atomistic formulation based on modeling elastic interactions of a binary alloy with harmonic springs whose equilibrium length is species dependent. It is demonstrated that the continuum limit for the strain field are the usual equations of linear elasticity for alloys and that they correctly capture the coarse-grained behavior of the displacement field. In addition, it is established that Euler-Lagrange equation of the continuum limit of the elastic energy will yield the same strain field equation. This is the same energy functional that is often used to model elastic effects in binary alloys. However, a direct calculation of the elastic energy atomistic model reveals that the continuum expression for the elastic energy is both qualitatively and quantitatively incorrect. This is because it does not take atomistic scale compositional nonuniformity into account. Importantly, this result also shows that finely mixed alloys tend to have more elastic energy than segregated systems, which is the exact opposite of predictions made by some continuum theories. It is also shown that for strained thin films the traditionally used effective misfit for alloys systematically underestimate the strain energy. In some models, this drawback is handled by including an elastic contribution to the enthalpy of mixing, which is characterized in terms of the continuum concentration. The direct calculation of the atomistic model reveals that this approach suffers serious difficulties. It is demonstrated that elastic contribution to the enthalpy of mixing is nonisotropic and scale dependent. It is also shown that such effects are present in density-functional theory calculations for the Si-Ge system. This work demonstrates that it is critical to include the microscopic arrangements in any elastic model to achieve even qualitatively correct behavior.

Faradaically selective membrane for liquid metal displacement batteries

NASA Astrophysics Data System (ADS)

Yin, Huayi; Chung, Brice; Chen, Fei; Ouchi, Takanari; Zhao, Ji; Tanaka, Nobuyuki; Sadoway, Donald R.

2018-02-01

In the realm of stationary energy storage, a plurality of candidate chemistries continues to vie for acceptance, among them the Na-NiCl2 displacement battery, which has eluded widespread adoption owing to the fragility of the β″-Al2O3 membrane. Here we report a porous electronically conductive membrane, which achieves chemical selectivity by preferred faradaic reaction instead of by regulated ionic conduction. Fitted with a porous membrane of TiN, a displacement cell comprising a liquid Pb positive electrode, a liquid Li-Pb negative electrode and a molten-salt electrolyte of PbCl2 dissolved in LiCl-KCl eutectic was cycled at a current density of 150 mA cm-2 at a temperature of 410 °C and exhibited a coulombic efficiency of 92% and a round-trip energy efficiency of 71%. As an indication of industrial scalability, we show comparable performance in a cell fitted with a faradaic membrane fashioned out of porous metal.

Displacement potential solution of a guided deep beam of composite materials under symmetric three-point bending

NASA Astrophysics Data System (ADS)

Rahman, M. Muzibur; Ahmad, S. Reaz

2017-12-01

An analytical investigation of elastic fields for a guided deep beam of orthotropic composite material having three point symmetric bending is carried out using displacement potential boundary modeling approach. Here, the formulation is developed as a single function of space variables defined in terms of displacement components, which has to satisfy the mixed type of boundary conditions. The relevant displacement and stress components are derived into infinite series using Fourier integral along with suitable polynomials coincided with boundary conditions. The results are presented mainly in the form of graphs and verified with finite element solutions using ANSYS. This study shows that the analytical and numerical solutions are in good agreement and thus enhances reliability of the displacement potential approach.

Functional outcomes of conservatively treated clavicle fractures

PubMed Central

Bajuri, Mohd Yazid; Maidin, S; Rauf, A; Baharuddin, M; Harjeet, S

2011-01-01

OBJECTIVE: The main aim of the study was to analyze the outcomes of clavicle fractures in adults treated non-surgically and to evaluate the clinical effects of displacement, fracture patterns, fracture location, fracture comminution, shortening and fracture union on shoulder function. METHODS: Seventy clavicle fractures were non-surgically treated in the Orthopedics Department at the Tuanku Ja'afar General Hospital, a tertiary care hospital in Seremban, Malaysia, an average of six months after injury. The clavicle fractures were treated conservatively with an arm sling and a figure-eight splint for three weeks. No attempt was made to reduce displaced fractures, and the patients were allowed immediate free-shoulder mobilization, as tolerated. They were prospectively evaluated clinically and radiographically. Shoulder function was evaluated using the Constant scoring technique. RESULTS: There were statistically significant functional outcome impairments in non-surgically treated clavicle fractures that correlated with the fracture type (comminution), the fracture displacement (21 mm or more), shortening (15 mm or more) and the fracture union (malunion). CONCLUSION: This article reveals the need for surgical intervention to treat clavicle fractures and improve shoulder functional outcomes. PMID:21655759

A simulation technique for 3D MR-guided acoustic radiation force imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Payne, Allison, E-mail: apayne@ucair.med.utah.edu; Bever, Josh de; Farrer, Alexis

2015-02-15

Purpose: In magnetic resonance-guided focused ultrasound (MRgFUS) therapies, the in situ characterization of the focal spot location and quality is critical. MR acoustic radiation force imaging (MR-ARFI) is a technique that measures the tissue displacement caused by the radiation force exerted by the ultrasound beam. This work presents a new technique to model the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model. Methods: When a steady-state point-source force acts internally in an infinite homogeneous medium, the displacement of the material in all directions is given by the Somigliana elastostatic tensor. The radiation forcemore » field, which is caused by absorption and reflection of the incident ultrasound intensity pattern, will be spatially distributed, and the tensor formulation takes the form of a convolution of a 3D Green’s function with the force field. The dynamic accumulation of MR phase during the ultrasound pulse can be theoretically accounted for through a time-of-arrival weighting of the Green’s function. This theoretical model was evaluated experimentally in gelatin phantoms of varied stiffness (125-, 175-, and 250-bloom). The acoustic and mechanical properties of the phantoms used as parameters of the model were measured using independent techniques. Displacements at focal depths of 30- and 45-mm in the phantoms were measured by a 3D spin echo MR-ARFI segmented-EPI sequence. Results: The simulated displacements agreed with the MR-ARFI measured displacements for all bloom values and focal depths with a normalized RMS difference of 0.055 (range 0.028–0.12). The displacement magnitude decreased and the displacement pattern broadened with increased bloom value for both focal depths, as predicted by the theory. Conclusions: A new technique that models the displacements caused by the radiation force of an ultrasound beam in a homogeneous tissue model theory has been rigorously validated through comparison with experimentally obtained 3D displacement data in homogeneous gelatin phantoms using a 3D MR-ARFI sequence. The agreement of the experimentally measured and simulated results demonstrates the potential to use MR-ARFI displacement data in MRgFUS therapies.« less

Elastic layer under axisymmetric indentation and surface energy effects

NASA Astrophysics Data System (ADS)

Intarit, Pong-in; Senjuntichai, Teerapong; Rungamornrat, Jaroon

2018-04-01

In this paper, a continuum-based approach is adopted to investigate the contact problem of an elastic layer with finite thickness and rigid base subjected to axisymmetric indentation with the consideration of surface energy effects. A complete Gurtin-Murdoch surface elasticity is employed to consider the influence of surface stresses. The indentation problem of a rigid frictionless punch with arbitrary axisymmetric profiles is formulated by employing the displacement Green's functions, derived with the aid of Hankel integral transform technique. The problem is solved by assuming the contact pressure distribution in terms of a linear combination of admissible functions and undetermined coefficients. Those coefficients are then obtained by employing a collocation technique and an efficient numerical quadrature scheme. The accuracy of proposed solution technique is verified by comparing with existing solutions for rigid indentation on an elastic half-space. Selected numerical results for the indenters with flat-ended cylindrical and paraboloidal punch profiles are presented to portray the influence of surface energy effects on elastic fields of the finite layer. It is found that the presence of surface stresses renders the layer stiffer, and the size-dependent behavior of elastic fields is observed in the present solutions. In addition, the surface energy effects become more pronounced with smaller contact area; thus, the influence of surface energy cannot be ignored in the analysis of indentation problem especially when the indenter size is very small such as in the case of nanoindentation.

Evidence that displacement activities facilitate behavioural transitions in ring-tailed lemurs.

PubMed

Buckley, Victoria; Semple, Stuart

2012-07-01

Displacement activities are behavioural patterns defined by their apparent irrelevance to an animal's ongoing actions. Despite being identified in diverse taxa, their function remains poorly understood. One hypothesis posits that displacement activities facilitate transitions between different behaviours by mediating changes in animals' motivational state. Under this hypothesis, it is predicted that displacement activities will occur more frequently around changes in behaviour than at other times, and also that rates of displacement activities will be higher before than after such behavioural transitions. We tested these two predictions in wild ring-tailed lemurs (Lemur catta). During focal observations, animals' behavioural state was continuously recorded, as were all occurrences of self-scratching, a common displacement activity in this species. Self-scratching rates were found to be significantly elevated both before and after behavioural transitions. Furthermore, self-scratching rates were significantly higher before behavioural transitions occurred than after. These results, therefore, provide support for the hypothesis that displacement activities facilitate behavioural transitions in L. catta. Copyright © 2012 Elsevier B.V. All rights reserved.

Applications of Displacement Transfer Functions to Deformed Shape Predictions of the G-III Swept-Wing Structure

NASA Technical Reports Server (NTRS)

Lung, Shun-Fat; Ko, William L.

2016-01-01

In support of the Adaptive Compliant Trailing Edge [ACTE] project at the NASA Armstrong Flight Research Center, displacement transfer functions were applied to the swept wing of a Gulfstream G-III airplane (Gulfstream Aerospace Corporation, Savannah, Georgia) to obtain deformed shape predictions. Four strainsensing lines (two on the lower surface, two on the upper surface) were used to calculate the deformed shape of the G III wing under bending and torsion. There being an insufficient number of surface strain sensors, the existing G III wing box finite element model was used to generate simulated surface strains for input to the displacement transfer functions. The resulting predicted deflections have good correlation with the finite-element generated deflections as well as the measured deflections from the ground load calibration test. The convergence study showed that the displacement prediction error at the G III wing tip can be reduced by increasing the number of strain stations (for each strain-sensing line) down to a minimum error of l.6 percent at 17 strain stations; using more than 17 strain stations yielded no benefit because the error slightly increased to 1.9% when 32 strain stations were used.

A complete solution of cartographic displacement based on elastic beams model and Delaunay triangulation

NASA Astrophysics Data System (ADS)

Liu, Y.; Guo, Q.; Sun, Y.

2014-04-01

In map production and generalization, it is inevitable to arise some spatial conflicts, but the detection and resolution of these spatial conflicts still requires manual operation. It is become a bottleneck hindering the development of automated cartographic generalization. Displacement is the most useful contextual operator that is often used for resolving the conflicts arising between two or more map objects. Automated generalization researches have reported many approaches of displacement including sequential approaches and optimization approaches. As an excellent optimization approach on the basis of energy minimization principles, elastic beams model has been used in resolving displacement problem of roads and buildings for several times. However, to realize a complete displacement solution, techniques of conflict detection and spatial context analysis should be also take into consideration. So we proposed a complete solution of displacement based on the combined use of elastic beams model and constrained Delaunay triangulation (CDT) in this paper. The solution designed as a cyclic and iterative process containing two phases: detection phase and displacement phase. In detection phase, CDT of map is use to detect proximity conflicts, identify spatial relationships and structures, and construct auxiliary structure, so as to support the displacement phase on the basis of elastic beams. In addition, for the improvements of displacement algorithm, a method for adaptive parameters setting and a new iterative strategy are put forward. Finally, we implemented our solution on a testing map generalization platform, and successfully tested it against 2 hand-generated test datasets of roads and buildings respectively.

Signal displacement in spiral-in acquisitions: simulations and implications for imaging in SFG regions.

PubMed

Brewer, Kimberly D; Rioux, James A; Klassen, Martyn; Bowen, Chris V; Beyea, Steven D

2012-07-01

Susceptibility field gradients (SFGs) cause problems for functional magnetic resonance imaging (fMRI) in regions like the orbital frontal lobes, leading to signal loss and image artifacts (signal displacement and "pile-up"). Pulse sequences with spiral-in k-space trajectories are often used when acquiring fMRI in SFG regions such as inferior/medial temporal cortex because it is believed that they have improved signal recovery and decreased signal displacement properties. Previously postulated theories explain differing reasons why spiral-in appears to perform better than spiral-out; however it is clear that multiple mechanisms are occurring in parallel. This study explores differences in spiral-in and spiral-out images using human and phantom empirical data, as well as simulations consistent with the phantom model. Using image simulations, the displacement of signal was characterized using point spread functions (PSFs) and target maps, the latter of which are conceptually inverse PSFs describing which spatial locations contribute signal to a particular voxel. The magnitude of both PSFs and target maps was found to be identical for spiral-out and spiral-in acquisitions, with signal in target maps being displaced from distant regions in both cases. However, differences in the phase of the signal displacement patterns that consequently lead to changes in the intervoxel phase coherence were found to be a significant mechanism explaining differences between the spiral sequences. The results demonstrate that spiral-in trajectories do preserve more total signal in SFG regions than spiral-out; however, spiral-in does not in fact exhibit decreased signal displacement. Given that this signal can be displaced by significant distances, its recovery may not be preferable for all fMRI applications. Copyright © 2012 Elsevier Inc. All rights reserved.

Experimental and FE displacement and polymerization stress of bonded restorations as a function of the C-Factor, volume and substrate stiffness.

PubMed

Boaro, Letícia Cristina Cidreira; Brandt, William Cunha; Meira, Josete Barbosa Cruz; Rodrigues, Flávia Pires; Palin, William M; Braga, Roberto Ruggiero

2014-02-01

To determine the free surface displacement of resin-composite restorations as a function of the C-Factor, volume and substrate stiffness, and to compare the results with interfacial stress values evaluated by finite element analysis (FEA). Surface displacement was determined by an extensometer using restorations with 4 or 6mm diameter and 1 or 2mm depth, prepared in either bovine teeth or glass. The maximum displacement of the free surface was monitored for 5 min from the start of photoactivation, at an acquisition rate of 1s(-1). Axisymmetric cavity models were performed by FEA. Structural stiffness and maximum stresses were investigated. For glass, displacement showed a stronger correlation with volume (r=0.771) than with C-Factor (r=0.395, p<0.001 for both). For teeth, a stronger correlation was found with C-Factor (r=0.709; p<0.001) than with volume (r=0.546, p<0.001). For similar dimensions, stress and displacement were defined by stiffness. Simultaneous increases in volume and C-Factor led to increases in stress and surface displacement. Maximum stresses were located at the cavosurface angle, internal angle (glass) and at the dentine-enamel junction (teeth). The displacement of the restoration's free surface was related to interfacial stress development. Structural stiffness seems to affect the shrinkage stress at the tooth/resin-composite interface in bonded restorations. Deep restorations are always problematic because they showed high shear stress, regardless of their width. FEA is the only tool capable of detecting shear stress due to polymerization as there is still no reliable experimental alternative. Copyright © 2013 Elsevier Ltd. All rights reserved.

Axial displacement of abutments into implants and implant replicas, with the tapered cone-screw internal connection, as a function of tightening torque.

PubMed

Dailey, Bruno; Jordan, Laurence; Blind, Olivier; Tavernier, Bruno

2009-01-01

The passive fit of a superstructure on implant abutments is essential to success. One source of error when using a tapered cone-screw internal connection may be the difference between the tightening torque level applied to the abutments by the laboratory technician compared to that applied by the treating clinician. The purpose of this study was to measure the axial displacement of tapered cone-screw abutments into implants and their replicas as a function of the tightening torque level. Twenty tapered cone-screw abutments were selected. Two groups were created: 10 abutments were secured into 10 implants, and 10 abutments were secured into 10 corresponding implant replicas. Each abutment was tightened in increasing increments of 5 Ncm, from 0 Ncm to 45 Ncm, with a torque controller. The length of each sample was measured repeatedly with an Electronic Digital Micrometer. The mean axial displacement for the implant group and the replica group was calculated. The data were analyzed by the Mann-Whitney and Spearman tests. For both groups, there was always an axial displacement of the abutment upon each incremental application of torque. The mean axial displacement values varied between 7 and 12 microm for the implant group and between 6 and 21 microm for the replica group at each 5-Ncm increment. From 0 to 45 Ncm, the total mean axial displacement values were 89 microm for the implant group and 122 microm for the replica group. There was a continuous axial displacement of the abutments into implants and implant replicas when the applied torque was raised from 0 to 45 Ncm. Torque applied above the level recommended by the manufacturer increased the difference in displacement between the two groups.

Chemistry at Work.

ERIC Educational Resources Information Center

Burke, Barbara A.

1997-01-01

Presents a demonstration which uses single displacement reactions to generate electricity. Illustrates the relationships between redox chemical reactions, electricity, chemical energy, and work. (JRH)

Substrate decomposition in galvanic displacement reaction: Contrast between gold and silver nanoparticle formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Tapas; Satpati, Biswarup, E-mail: biswarup.satpati@saha.ac.in; Kabiraj, D.

We have investigated substrate decomposition during formation of silver and gold nanoparticles in galvanic displacement reaction on germanium surfaces. Silver and gold nanoparticles were synthesized by electroless deposition on sputter coated germanium thin film (∼ 200 nm) grown initially on silicon substrate. The nanoparticles formation and the substrate corrosion were studied using scanning transmission electron microscopy (STEM) and the energy dispersive X-ray (EDX) spectroscopy.

Proton irradiation effects on advanced digital and microwave III-V components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hash, G.L.; Schwank, J.R.; Shaneyfelt, M.R.

1994-09-01

A wide range of advanced III-V components suitable for use in high-speed satellite communication systems were evaluated for displacement damage and single-event effects in high-energy, high-fluence proton environments. Transistors and integrated circuits (both digital and MMIC) were irradiated with protons at energies from 41 to 197 MeV and at fluences from 10{sup 10} to 2 {times} 10{sup 14} protons/cm{sup 2}. Large soft-error rates were measured for digital GaAs MESFET (3 {times} 10{sup {minus}5} errors/bit-day) and heterojunction bipolar circuits (10{sup {minus}5} errors/bit-day). No transient signals were detected from MMIC circuits. The largest degradation in transistor response caused by displacement damage wasmore » observed for 1.0-{mu}m depletion- and enhancement-mode MESFET transistors. Shorter gate length MESFET transistors and HEMT transistors exhibited less displacement-induced damage. These results show that memory-intensive GaAs digital circuits may result in significant system degradation due to single-event upset in natural and man-made space environments. However, displacement damage effects should not be a limiting factor for fluence levels up to 10{sup 14} protons/cm{sup 2} [equivalent to total doses in excess of 10 Mrad(GaAs)].« less

Proton irradiation effects on advanced digital and microwave III-V components

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hash, G.L.; Schwank, J.R.; Shaneyfelt, M.R.

1994-12-01

A wide range of advanced III-V components suitable for use in high-speed satellite communication systems were evaluated for displacement damage and single-event effects in high-energy, high-fluence proton environments. Transistors and integrated circuits (both digital and MMIC) were irradiated with protons at energies from 41 to 197 MeV and at fluences from 10[sup 10] to 2 [times] 10[sup 14] protons/cm[sup 2]. Large soft-error rates were measured for digital GaAs MESFET (3 [times] 10[sup [minus]5] errors/bit-day) and heterojunction bipolar circuits (10[sup [minus]5] errors/bit-day). No transient signals were detected from MMIC circuits. The largest degradation in transistor response caused by displacement damage wasmore » observed for 1.0-[mu]m depletion- and enhancement-mode MESFET transistors. Shorter gate length MESFET transistors and HEMT transistors exhibited less displacement-induced damage. These results show that memory-intensive GaAs digital circuits may result in significant system degradation due to single-event upset in natural and man-made space environments. However, displacement damage effects should not be a limiting factor for fluence levels up to 10[sup 14] protons/cm[sup 2] [equivalent to total doses in excess of 10 Mrad (GaAs)].« less

Electroactive nanostructured polymer actuators fabricated using sulfonated styrenic pentablock copolymer/montmorillonite/ionic liquid nanocomposite membranes

NASA Astrophysics Data System (ADS)

Lee, Jang-Woo; Hong, Soon Man; Koo, Chong Min

2014-08-01

High-bendable, air-operable ionic polymer-metal composite (IPMC) actuators composed of electroactive nanostructured middle-block sulfonated styrenic pentablock copolymer (SSPB)/sulfonated montmorillonite (s-MMT) nanocomposite electrolyte membranes with bulky imidazolium ionic liquids (ILs) incorporated were fabricated and their bending actuation performances were evaluated. The SSPB-based IPMC actuators showed larger air-operable bending displacements, higher displacement rates, and higher energy efficiency of actuations without conventional IPMC bottlenecks, including back relaxation and actuation instability during actuation in air, than the Nafion counterpart. Incorporation of s-MMT into the SSPB matrix further enhanced the actuation performance of the IPMC actuators in terms of displacement, displacement rate, and energy efficiency. The remarkably high performance of the SSPB/s-MMT/IL IPMCs was considered to be due to the microphase-separated large ionic domains of the SSPB (the average diameter of the ionic domain: ca. 20 nm) and the role of s-MMT as an ionic bridge between the ionic domains, and the ion pumping effect of the bulky imidazolium cations of the ILs as well. The microphase-separated nanostructure of the composite membranes caused a high dimensional stability upon swelling in the presence of ILs, which effectively preserved the original electrode resistance against swelling, leading to a high actuation performance of IPMC.

Research on theoretical optimization and experimental verification of minimum resistance hull form based on Rankine source method

NASA Astrophysics Data System (ADS)

Zhang, Bao-Ji; Zhang, Zhu-Xin

2015-09-01

To obtain low resistance and high efficiency energy-saving ship, minimum total resistance hull form design method is studied based on potential flow theory of wave-making resistance and considering the effects of tail viscous separation. With the sum of wave resistance and viscous resistance as objective functions and the parameters of B-Spline function as design variables, mathematical models are built using Nonlinear Programming Method (NLP) ensuring the basic limit of displacement and considering rear viscous separation. We develop ship lines optimization procedures with intellectual property rights. Series60 is used as parent ship in optimization design to obtain improved ship (Series60-1) theoretically. Then drag tests for the improved ship (Series60-1) is made to get the actual minimum total resistance hull form.

Transient response of multidegree-of-freedom linear systems to forcing functions with inequality constraints

NASA Technical Reports Server (NTRS)

Michalopoulos, C. D.

1974-01-01

Optimal control theory is applied to analyze the transient response of discrete linear systems to forcing functions with unknown time dependence but having known bounds. Particular attention is given to forcing functions which include: (1) maximum displacement of any given mass element, (2) maximum relative displacement of any two adjacent masses, and (3) maximum acceleration of a given mass. Linear mechanical systems with an arbitrary number of degrees of freedom and only one forcing function acting are considered. In the general case, the desired forcing function is found to be a function that switches from the upper-to-lower bound and vice-versa at certain moments of time. A general procedure for finding such switching times is set forth.

Uranium phase diagram from first principles

NASA Astrophysics Data System (ADS)

Yanilkin, Alexey; Kruglov, Ivan; Migdal, Kirill; Oganov, Artem; Pokatashkin, Pavel; Sergeev, Oleg

2017-06-01

The work is devoted to the investigation of uranium phase diagram up to pressure of 1 TPa and temperature of 15 kK based on density functional theory. First of all the comparison of pseudopotential and full potential calculations is carried out for different uranium phases. In the second step, phase diagram at zero temperature is investigated by means of program USPEX and pseudopotential calculations. Stable and metastable structures with close energies are selected. In order to obtain phase diagram at finite temperatures the preliminary selection of stable phases is made by free energy calculation based on small displacement method. For remaining candidates the accurate values of free energy are obtained by means of thermodynamic integration method (TIM). For this purpose quantum molecular dynamics are carried out at different volumes and temperatures. Interatomic potentials based machine learning are developed in order to consider large systems and long times for TIM. The potentials reproduce the free energy with the accuracy 1-5 meV/atom, which is sufficient for prediction of phase transitions. The equilibrium curves of different phases are obtained based on free energies. Melting curve is calculated by modified Z-method with developed potential.

Unleashing elastic energy: dynamics of energy release in rubber bands and impulsive biological systems

NASA Astrophysics Data System (ADS)

Ilton, Mark; Cox, Suzanne; Egelmeers, Thijs; Patek, S. N.; Crosby, Alfred J.

Impulsive biological systems - which include mantis shrimp, trap-jaw ants, and venus fly traps - can reach high speeds by using elastic elements to store and rapidly release energy. The material behavior and shape changes critical to achieving rapid energy release in these systems are largely unknown due to limitations of materials testing instruments operating at high speed and large displacement. In this work, we perform fundamental, proof-of-concept measurements on the tensile retraction of elastomers. Using high speed imaging, the kinematics of retraction are measured for elastomers with varying mechanical properties and geometry. Based on the kinematics, the rate of energy dissipation in the material is determined as a function of strain and strain-rate, along with a scaling relation which describes the dependence of maximum velocity on material properties. Understanding this scaling relation along with the material failure limits of the elastomer allows the prediction of material properties required for optimal performance. We demonstrate this concept experimentally by optimizing for maximum velocity in our synthetic model system, and achieve retraction velocities that exceed those in biological impulsive systems. This model system provides a foundation for future work connecting continuum performance to molecular architecture in impulsive systems.

Posterior papillary muscle anchoring affects remote myofiber stress and pump function: finite element analysis.

PubMed

Pantoja, Joe Luis; Ge, Liang; Zhang, Zhihong; Morrel, William G; Guccione, Julius M; Grossi, Eugene A; Ratcliffe, Mark B

2014-10-01

The role of posterior papillary muscle anchoring (PPMA) in the management of chronic ischemic mitral regurgitation (CIMR) is controversial. We studied the effect of anchoring point direction and relocation displacement on left ventricular (LV) regional myofiber stress and pump function. Previously described finite element models of sheep 16 weeks after posterolateral myocardial infarction (MI) were used. True-sized mitral annuloplasty (MA) ring insertion plus different PPM anchoring techniques were simulated. Anchoring points tested included both commissures and the central anterior mitral annulus; relocation displacement varied from 10% to 40% of baseline diastolic distance from the PPM to the anchor points on the annulus. For each reconstruction scenario, myofiber stress in the MI, border zone, and remote myocardium as well as pump function were calculated. PPMA caused reductions in myofiber stress at end-diastole and end-systole in all regions of the left ventricle that were proportional to the relocation displacement. Although stress reduction was greatest in the MI region, it also occurred in the remote region. The maximum 40% displacement caused a slight reduction in LV pump function. However, with the correction of regurgitation by MA plus PPMA, there was an overall increase in forward stroke volume. Finally, anchoring point direction had no effect on myofiber stress or pump function. PPMA reduces remote myofiber stress, which is proportional to the absolute distance of relocation and independent of anchoring point. Aggressive use of PPMA techniques to reduce remote myofiber stress may accelerate reverse LV remodeling without impairing LV function. Copyright © 2014 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

Free-piston regenerative hot gas hydraulic engine

NASA Technical Reports Server (NTRS)

Beremand, D. G. (Inventor)

1980-01-01

A displacer piston which is driven pneumatically by a high-pressure or low-pressure gas is included in a free-piston regenerative hydraulic engine. Actuation of the displacer piston circulates the working fluid through a heater, a regenerator and a cooler. The present invention includes an inertial mass such as a piston or a hydraulic fluid column to effectively store and supply energy during portions of the cycle. Power is transmitted from the working fluid to a hydraulic fluid across a diaphragm or lightweight piston to achieve a hydraulic power out-put. The displacer piston of the present invention may be driven pneumatically, hydraulically or electromagnetically. In addition, the displacer piston and the inertial mass of the present invention may be positioned on the same side of the diaphragm member or may be separated by the diaphragm member.

Displacement Cascade Damage Production in Metals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stoller, Roger E; Malerba, Lorenzo; Nordlund, Kai

Radiation-induced changes in microstructure and mechanical properties in structural materials are the result of a complex set of physical processes initiated by the collision between an energetic particle (neutron or ion) and an atom in the lattice. This primary damage event is called an atomic displacement cascade. The simplest description of a displacement cascade is to view it as a series of many billiard-ball-like elastic collisions among the atoms in the material. This chapter describes the formation and evolution of this primary radiation damage mechanism to provide an overview of how stable defects are formed by displacement cascades, as wellmore » as the nature and morphology of the defects themselves. The impact of the relevant variables such as cascade energy and irradiation temperature is discussed, and defect formation in different materials is compared.« less

Extension-torsion coupling behavior of advanced composite tilt-rotor blades

NASA Technical Reports Server (NTRS)

Kosmatka, J. B.

1989-01-01

An analytic model was developed to study the extension-bend-twist coupling behavior of an advanced composite helicopter or tilt-rotor blade. The outer surface of the blade is defined by rotating an arbitrary cross section about an initial twist axis. The cross section can be nonhomogeneous and composed of generally anisotropic materials. The model is developed based upon a three dimensional elasticity approach that is recast as a coupled two-dimensional boundary value problem defined in a curvilinear coordinate system. Displacement solutions are written in terms of known functions that represent extension, bending, and twisting and unknown functions for local cross section deformations. The unknown local deformation functions are determined by applying the principle of minimum potential energy to the discretized two-dimensional cross section. This is an application of the Ritz method, where the trial function family is the displacement field associated with a finite element (8-node isoparametric quadrilaterals) representation of the section. A computer program was written where the cross section is discretized into 8-node quadrilateral subregions. Initially the program was verified using previously published results (both three-dimensional elasticity and technical beam theory) for pretwisted isotropic bars with an elliptical cross section. In addition, solid and thin-wall multi-cell NACA-0012 airfoil sections were analyzed to illustrate the pronounced effects that pretwist, initial twist axis location, and spar location has on coupled behavior. Currently, a series of advanced composite airfoils are being modeled in order to assess how the use of laminated composite materials interacts with pretwist to alter the coupling behavior of the blade. These studies will investigate the use of different ply angle orientations and the use of symmetric versus unsymmetric laminates.

A Simple Sensor Model for THUNDER Actuators

NASA Technical Reports Server (NTRS)

Campbell, Joel F.; Bryant, Robert G.

2009-01-01

A quasi-static (low frequency) model is developed for THUNDER actuators configured as displacement sensors based on a simple Raleigh-Ritz technique. This model is used to calculate charge as a function of displacement. Using this and the calculated capacitance, voltage vs. displacement and voltage vs. electrical load curves are generated and compared with measurements. It is shown this model gives acceptable results and is useful for determining rough estimates of sensor output for various loads, laminate configurations and thicknesses.

Closed reduction of displaced or dislocated mandibular condyle fractures in children using threaded Kirschner wire and external rubber traction.

PubMed

Kim, J H; Nam, D H

2015-10-01

Most surgeons agree that closed treatment provides the best results for condylar fractures in children. Nevertheless, treatment of the paediatric mandibular condyle fracture that is severely displaced or dislocated is controversial. The purpose of this study was to investigate the long-term clinical and radiological outcomes following the treatment of displaced or dislocated condylar fractures in children using threaded Kirschner wire and external rubber traction. This procedure can strengthen the advantage of closed reduction and make up for the shortcomings of open reduction. From March 1, 2005 to December 25, 2011, 11 children aged between 4 and 12 years with displaced or dislocated mandibular condyle fractures were treated using threaded Kirschner wire and external rubber traction under portable C-arm fluoroscopy. All patients had unilateral displaced or dislocated condylar fractures. The follow-up period ranged from 24 to 42 months (mean 29.3 months). Normal occlusion and pain-free function of the temporomandibular joint, without deviation or limitation of jaw opening, was achieved in all patients. This closed reduction technique in displaced or dislocated condylar fractures in children offers a reliable solution in preventing the unfavourable sequelae of closed treatment and the open technique, such as altered morphology, functional disturbances, and facial nerve damage. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

On the biophysics and kinetics of toehold-mediated DNA strand displacement

PubMed Central

Srinivas, Niranjan; Ouldridge, Thomas E.; Šulc, Petr; Schaeffer, Joseph M.; Yurke, Bernard; Louis, Ard A.; Doye, Jonathan P. K.; Winfree, Erik

2013-01-01

Dynamic DNA nanotechnology often uses toehold-mediated strand displacement for controlling reaction kinetics. Although the dependence of strand displacement kinetics on toehold length has been experimentally characterized and phenomenologically modeled, detailed biophysical understanding has remained elusive. Here, we study strand displacement at multiple levels of detail, using an intuitive model of a random walk on a 1D energy landscape, a secondary structure kinetics model with single base-pair steps and a coarse-grained molecular model that incorporates 3D geometric and steric effects. Further, we experimentally investigate the thermodynamics of three-way branch migration. Two factors explain the dependence of strand displacement kinetics on toehold length: (i) the physical process by which a single step of branch migration occurs is significantly slower than the fraying of a single base pair and (ii) initiating branch migration incurs a thermodynamic penalty, not captured by state-of-the-art nearest neighbor models of DNA, due to the additional overhang it engenders at the junction. Our findings are consistent with previously measured or inferred rates for hybridization, fraying and branch migration, and they provide a biophysical explanation of strand displacement kinetics. Our work paves the way for accurate modeling of strand displacement cascades, which would facilitate the simulation and construction of more complex molecular systems. PMID:24019238

On the biophysics and kinetics of toehold-mediated DNA strand displacement.

PubMed

Srinivas, Niranjan; Ouldridge, Thomas E; Sulc, Petr; Schaeffer, Joseph M; Yurke, Bernard; Louis, Ard A; Doye, Jonathan P K; Winfree, Erik

2013-12-01

Dynamic DNA nanotechnology often uses toehold-mediated strand displacement for controlling reaction kinetics. Although the dependence of strand displacement kinetics on toehold length has been experimentally characterized and phenomenologically modeled, detailed biophysical understanding has remained elusive. Here, we study strand displacement at multiple levels of detail, using an intuitive model of a random walk on a 1D energy landscape, a secondary structure kinetics model with single base-pair steps and a coarse-grained molecular model that incorporates 3D geometric and steric effects. Further, we experimentally investigate the thermodynamics of three-way branch migration. Two factors explain the dependence of strand displacement kinetics on toehold length: (i) the physical process by which a single step of branch migration occurs is significantly slower than the fraying of a single base pair and (ii) initiating branch migration incurs a thermodynamic penalty, not captured by state-of-the-art nearest neighbor models of DNA, due to the additional overhang it engenders at the junction. Our findings are consistent with previously measured or inferred rates for hybridization, fraying and branch migration, and they provide a biophysical explanation of strand displacement kinetics. Our work paves the way for accurate modeling of strand displacement cascades, which would facilitate the simulation and construction of more complex molecular systems.

Designing Radiation Resistance in Materials for Fusion Energy

NASA Astrophysics Data System (ADS)

Zinkle, S. J.; Snead, L. L.

2014-07-01

Proposed fusion and advanced (Generation IV) fission energy systems require high-performance materials capable of satisfactory operation up to neutron damage levels approaching 200 atomic displacements per atom with large amounts of transmutant hydrogen and helium isotopes. After a brief overview of fusion reactor concepts and radiation effects phenomena in structural and functional (nonstructural) materials, three fundamental options for designing radiation resistance are outlined: Utilize matrix phases with inherent radiation tolerance, select materials in which vacancies are immobile at the design operating temperatures, or engineer materials with high sink densities for point defect recombination. Environmental and safety considerations impose several additional restrictions on potential materials systems, but reduced-activation ferritic/martensitic steels (including thermomechanically treated and oxide dispersion-strengthened options) and silicon carbide ceramic composites emerge as robust structural materials options. Materials modeling (including computational thermodynamics) and advanced manufacturing methods are poised to exert a major impact in the next ten years.

Sound waves and flexural mode dynamics in two-dimensional crystals

NASA Astrophysics Data System (ADS)

Michel, K. H.; Scuracchio, P.; Peeters, F. M.

2017-09-01

Starting from a Hamiltonian with anharmonic coupling between in-plane acoustic displacements and out-of-plane (flexural) modes, we derived coupled equations of motion for in-plane displacements correlations and flexural mode density fluctuations. Linear response theory and time-dependent thermal Green's functions techniques are applied in order to obtain different response functions. As external perturbations we allow for stresses and thermal heat sources. The displacement correlations are described by a Dyson equation where the flexural density distribution enters as an additional perturbation. The flexural density distribution satisfies a kinetic equation where the in-plane lattice displacements act as a perturbation. In the hydrodynamic limit this system of coupled equations is at the basis of a unified description of elastic and thermal phenomena, such as isothermal versus adiabatic sound motion and thermal conductivity versus second sound. The general theory is formulated in view of application to graphene, two-dimensional h-BN, and 2H-transition metal dichalcogenides and oxides.

Understanding of assembly phenomena by aromatic-aromatic interactions: benzene dimer and the substituted systems.

PubMed

Lee, Eun Cheol; Kim, Dongwook; Jurecka, Petr; Tarakeshwar, P; Hobza, Pavel; Kim, Kwang S

2007-05-10

Interactions involving aromatic rings are important in molecular/biomolecular assembly and engineering. As a consequence, there have been a number of investigations on dimers involving benzene or other substituted pi systems. In this Feature Article, we examine the relevance of the magnitudes of their attractive and repulsive interaction energy components in governing the geometries of several pi-pi systems. The geometries and the associated binding energies were evaluated at the complete basis set (CBS) limit of coupled cluster theory with singles, doubles, and perturbative triples excitations [CCSD(T)] using a least biased scheme for the given data set. The results for the benzene dimer indicate that the floppy T-shaped structure (center-to-center distance: 4.96 A, with an axial benzene off-centered above the facial benzene) is isoenergetic in zero-point-energy (ZPE) corrected binding energy (D0) to the displaced-stacked structure (vertical interplanar distance: 3.54 A). However, the T-shaped structure is likely to be slightly more stable (D0 approximately equal to 2.4-2.5 kcal/mol) if quadruple excitations are included in the coupled cluster calculations. The presence of substituents on the aromatic ring, irrespective of their electron withdrawing or donating nature, leads to an increase in the binding energy, and the displaced-stacked conformations are more stabilized than the T-shaped conformers. This explains the wide prevalence of displaced stacked structures in organic crystals. Despite that the dispersion energy is dominating, the substituent as well as the conformational effects are correlated to the electrostatic interaction. This electrostatic origin implies that the substituent effect would be reduced in polar solution, but important in apolar media, in particular, for assembling processes.

Partial proximal tibia fractures

PubMed Central

Raschke, Michael J.; Kittl, Christoph; Domnick, Christoph

2017-01-01

Partial tibial plateau fractures may occur as a consequence of either valgus or varus trauma combined with a rotational and axial compression component. High-energy trauma may result in a more complex and multi-fragmented fracture pattern, which occurs predominantly in young people. Conversely, a low-energy mechanism may lead to a pure depression fracture in the older population with weaker bone density. Pre-operative classification of these fractures, by Müller AO, Schatzker or novel CT-based methods, helps to understand the fracture pattern and choose the surgical approach and treatment strategy in accordance with estimated bone mineral density and the individual history of each patient. Non-operative treatment may be considered for non-displaced intra-articular fractures of the lateral tibial condyle. Intra-articular joint displacement ⩾ 2 mm, open fractures or fractures of the medial condyle should be reduced and fixed operatively. Autologous, allogenic and synthetic bone substitutes can be used to fill bone defects. A variety of minimally invasive approaches, temporary osteotomies and novel techniques (e.g. arthroscopically assisted reduction or ‘jail-type’ screw osteosynthesis) offer a range of choices for the individual and are potentially less invasive treatments. Rehabilitation protocols should be carefully planned according to the degree of stability achieved by internal fixation, bone mineral density and other patient-specific factors (age, compliance, mobility). To avoid stiffness, early functional mobilisation plays a major role in rehabilitation. In the elderly, low-energy trauma and impression fractures are indicators for the further screening and treatment of osteoporosis. Cite this article: EFORT Open Rev 2017;2. DOI: 10.1302/2058-5241.2.160067. Originally published online at www.efortopenreviews.org PMID:28630761

3-D in vitro estimation of temperature using the change in backscattered ultrasonic energy.

PubMed

Arthur, R Martin; Basu, Debomita; Guo, Yuzheng; Trobaugh, Jason W; Moros, Eduardo G

2010-08-01

Temperature imaging with a non-invasive modality to monitor the heating of tumors during hyperthermia treatment is an attractive alternative to sparse invasive measurement. Previously, we predicted monotonic changes in backscattered energy (CBE) of ultrasound with temperature for certain sub-wavelength scatterers. We also measured CBE values similar to our predictions in bovine liver, turkey breast muscle, and pork rib muscle in 2-D in vitro studies and in nude mice during 2-D in vivo studies. To extend these studies to three dimensions, we compensated for motion and measured CBE in turkey breast muscle. 3-D data sets were assembled from images formed by a phased-array imager with a 7.5-MHz linear probe moved in 0.6-mm steps in elevation during uniform heating from 37 to 45 degrees C in 0.5 degrees C increments. We used cross-correlation as a similarity measure in RF signals to automatically track feature displacement as a function of temperature. Feature displacement was non-rigid. Envelopes of image regions, compensated for non-rigid motion, were found with the Hilbert transform then smoothed with a 3 x 3 running average filter before forming the backscattered energy at each pixel. CBE in 3-D motion-compensated images was nearly linear with an average sensitivity of 0.30 dB/ degrees C. 3-D estimation of temperature in separate tissue regions had errors with a maximum standard deviation of about 0.5 degrees C over 1-cm(3) volumes. Success of CBE temperature estimation based on 3-D non-rigid tracking and compensation for real and apparent motion of image features could serve as the foundation for the eventual generation of 3-D temperature maps in soft tissue in a non-invasive, convenient, and low-cost way in clinical hyperthermia.

Correcting the vertical component of ocean bottom seismometers for the effects of tilt and compliance

NASA Astrophysics Data System (ADS)

Bell, S. W.; Forsyth, D. W.

2013-12-01

Typically there are very high noise levels at long periods on the horizontal components of ocean bottom seismographs due to the turbulent interaction of bottom currents with the seismometer package on the seafloor. When there is a slight tilt of the instrument, some of the horizontal displacement caused by bottom currents leaks onto the vertical component record, which can severely increase the apparent vertical noise. Another major type of noise, compliance noise, is created when pressure variations associated with water (gravity) waves deform the seabed. Compliance noise increases with decreasing water depth, and at water depths of less than a few hundred meters, compliance noise typically obscures most earthquake signals. Following Crawford and Webb (2000), we have developed a methodology for reducing these noise sources by 1-2 orders of magnitude, revealing many events that could not be distinguished before noise reduction. Our methodology relies on transfer functions between different channels. We calculate the compliance noise in the vertical displacement record by applying a transfer function to the differential pressure gauge record. Similarly, we calculate the tilt-induced bottom current noise in the vertical displacement record by applying a transfer function to the horizontal displacement records. Using data from the Cascadia experiment and other experiments, we calculate these transfer functions at a range of stations with varying tilts and water depths. The compliance noise transfer function depends strongly on water depth, and we provide a theoretical and empirical description of this dependence. Tilt noise appears to be very highly correlated with instrument design, with negligible tilt noise observed for the 'abalone' instruments from the Scripps Institute of Oceanography and significant tilt observed for the Woods Hole Oceanographic Institution instruments in the first year deployment of the Cascadia experiment. Tilt orientation appears relatively constant, but we observe significant day-to-day variation in tilt angle, requiring the calculation of a tilt transfer function for each individual day for optimum removal of bottom current noise. In removing the compliance noise, there is some distortion of the signal. We show how to correct for this distortion using theoretical and empirical transfer functions between pressure and displacement records for seismic signals.

Control of base-excited dynamical systems through piezoelectric energy harvesting absorber

NASA Astrophysics Data System (ADS)

Abdelmoula, H.; Dai, H. L.; Abdelkefi, A.; Wang, L.

2017-09-01

The spring-mass absorber usually offers a good control to dynamical systems under direct base excitations for a specific value of the excitation frequency. As the vibrational energy of a primary dynamical system is transferred to the absorber, it gets dissipated. In this study, this energy is no longer dissipated but converted to available electrical power by designing efficient energy harvesters. A novel design of a piezoelectric beam installed inside an elastically-mounted dynamical system undergoing base excitations is considered. A design is carried out in order to determine the properties and dimensions of the energy harvester with the constraint of simultaneously decreasing the oscillating amplitudes of the primary dynamical system and increasing the harvested power of the energy harvesting absorber. An analytical model for the coupled system is constructed using Euler-Lagrange principle and Galerkin discretization. Different strategies for controlling the primary structure displacement and enhancing the harvested power as functions of the electrical load resistance and thickness of the beam substrate are performed. The linear polynomial approximation of the system’s key parameters as a function of the beam’s substrate thickness is first carried out. Then, the gradient method is applied to determine the adequate values of the electrical load resistance and thickness of the substrate under the constraints of minimizing the amplitudes of the primary structure or maximizing the levels of the harvested power. After that, an iterative strategy is considered in order to simultaneously minimize the amplitudes of the primary structure and maximize the levels of the harvested power as functions of the thickness of the substrate and electrical load resistance. In addition to harmonic excitations, the coupled system subjected to a white noise is explored. Through this analysis, the load resistance and thickness of the substrate of the piezoelectric energy harvester are determined. It is shown that, in addition to efficiently control the oscillating amplitudes of the primary structure, broadband resonance regions can take place and hence high levels of the harvested power are obtained.

Structure and function of the undulating membrane in spermatozoan propulsion in the toad Bufo marinus

PubMed Central

1980-01-01

Accessory fibers in most sperm surround the axoneme so that their function in propulsion is difficult to assess. In the sperm of the toad Bufo marinus, an accessory fiber is displaced from the axoneme, being connected to it by the thin undulating membrane in such a way that the movement of axoneme and accessory fiber can be viewed independently. The axoneme is highly convoluted in whole mounts, and the axial fiber is straight. Cinemicrographic analysis shows that it is the longer, flexuous fiber, the presumed axoneme, that move actively. The accessory fiber follows it passively with a lower amplitude of movement. The accessory fiber does not move independent of the axoneme, even after demembranation and reactivation of the sperm. On the basis of anatomical relations in the neck region, it appears that the accessory fibers of amphibians are analogous to the dense fibers of mammalian sperm. SDS polyacrylamide gel electrophoresis of demembranated toad sperm tails reveals two principal proteins in addition to the tubulins, the former probably arising from the accessory fibers and the matrix of the undulating membrane. The function of displacing an accessory fiber into an undulating membrane may be to provide stiffness for the tail without incurring an energy deficit large enough to require a long middle piece. A long middle piece is not present in toad sperm, in contrast to those sperm that have accessory fibers around the axoneme. However, the toad sperm suffers a reduction in speed of about one- third, compared with the speed expected for a sperm without an undulating membrane. PMID:6771299

Outcome Determining Factors for displaced Intra-articular Calcaneal Fractures treated operatively

PubMed Central

Chan, KL; Idham, HM; Izani, IM; Nahulan, T

2015-01-01

Introduction: Calcaneal fractures are caused by high energy trauma and mostly are intra-articular fractures. Nondisplaced intra-articular calcaneal fracture (IACF) can be treated non-operatively. However, displaced intra-articular need to be reduced and fixed anatomically to facilitate early ankle rehabilitation and minimize functional impairment. This study was done to find out the outcome of the IACF patients who underwent operative treatment. Methods: 62 patients with IACF were selected in this study and had been followed up from June 2009 to May 2013. They were placed into two groups; the operative treated and non-operative treated groups. Bilateral ankle lateral view plain radiographs were taken for comparison of the Bohler and Gissane angles. Both groups of patients were assessed by the Maryland Foot Score (MFS) and the SF-36v2 general health survey questionnaire. The ability of the patients to perform activity of daily living (ADL) and /or return to work (RTW) was assessed as well. Results: The operative treatment group of displaced IACF patients achieved no significant better scores in the mean MFS and SF-36v2 mean scores as compared to non operated cases. There was no difference in RTW between the 2 groups, but earlier ADL was recorded in the operated group. However, this study had found 5 associated factors which causes major effect to the patients’ outcome to treatment. Conclusions: The patient’s compliance with post-operative rehabilitation regimen were found to be significantly related with the outcomes. PMID:28611903

Conformational energy landscape of the acyl pocket loop in acetylcholinesterase: a Monte Carlo-generalized Born model study.

PubMed

Carlacci, Louis; Millard, Charles B; Olson, Mark A

2004-10-01

The X-ray crystal structure of the reaction product of acetylcholinesterase (AChE) with the inhibitor diisopropylphosphorofluoridate (DFP) showed significant structural displacement in a loop segment of residues 287-290. To understand this conformational selection, a Monte Carlo (MC) simulation study was performed of the energy landscape for the loop segment. A computational strategy was applied by using a combined simulated annealing and room temperature Metropolis sampling approach with solvent polarization modeled by a generalized Born (GB) approximation. Results from thermal annealing reveal a landscape topology of broader basin opening and greater distribution of energies for the displaced loop conformation, while the ensemble average of conformations at 298 K favored a shift in populations toward the native by a free-energy difference in good agreement with the estimated experimental value. Residue motions along a reaction profile of loop conformational reorganization are proposed where Arg-289 is critical in determining electrostatic effects of solvent interaction versus Coulombic charging.

Finite Element Analysis in Concurrent Processing: Computational Issues

NASA Technical Reports Server (NTRS)

Sobieszczanski-Sobieski, Jaroslaw; Watson, Brian; Vanderplaats, Garrett

2004-01-01

The purpose of this research is to investigate the potential application of new methods for solving large-scale static structural problems on concurrent computers. It is well known that traditional single-processor computational speed will be limited by inherent physical limits. The only path to achieve higher computational speeds lies through concurrent processing. Traditional factorization solution methods for sparse matrices are ill suited for concurrent processing because the null entries get filled, leading to high communication and memory requirements. The research reported herein investigates alternatives to factorization that promise a greater potential to achieve high concurrent computing efficiency. Two methods, and their variants, based on direct energy minimization are studied: a) minimization of the strain energy using the displacement method formulation; b) constrained minimization of the complementary strain energy using the force method formulation. Initial results indicated that in the context of the direct energy minimization the displacement formulation experienced convergence and accuracy difficulties while the force formulation showed promising potential.

(Project 13-5292) Correlating thermal and mechanical coupling based multiphysics behavior of nuclear materials through in-situ measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tomar, Vikas

Irradiations and post characterization experiments were performed first on Zr samples. This step will help understand the effect of the 2.5% alloying elements on the behavior of Zircaloy-4 (PWR cladding material) when compared to pure Zr. Irradiation flux measurements and sample temperature calibrations were performed at different energies prior to the irradiation experiments. Irradiations were performed with two different energy regimes1: non-displacment energies and displacement energies. Time was also dedicated to optimize transmission electron microscopy (TEM) sample preparation conditions via electropolishing technique. This step is crucial to prepare TEM samples for the in-situ TEM/irradiation experiments (Year 2). In addition, Zircaloy-4more » samples are being prepared for irradiation, and a setup is built by one of our collaborators (Dr. Mert Efe) to prepare ultrafine (UF) and nanocrystalline (NC) Zircaloy-4 samples for comparison with the commercial Zircaloy-4 samples.« less

INFLUENCE OF MASS ON DISPLACEMENT THRESHOLD

DOE Office of Scientific and Technical Information (OSTI.GOV)

Setyawan, Wahyu; Selby, A.; Nandipati, Giridhar

2014-12-30

Molecular dynamics simulations are performed to investigate the effect of mass on displacement threshold energy in Cr, Mo, Fe and W. For each interatomic potential, the mass of the atoms is varied among those metals for a total of 16 combinations. The average threshold energy over all crystal directions is calculated within the irreducible crystal directions using appropriate weighting factors. The weighting factors account for the different number of equivalent directions among the grid points and the different solid angle coverage of each grid point. The grid points are constructed with a Miller index increment of 1/24 for a totalmore » of 325 points. For each direction, 10 simulations each with a different primary-knock-on atom are performed. The results show that for each interatomic potential, the average threshold energy is insensitive to the mass; i.e., the values are the same within the standard error. In the future, the effect of mass on high-energy cascades for a given interatomic potential will be investigated.« less

GMTIFS: cryogenic rotary mechanisms for the GMT Integral-Field Spectrograph

NASA Astrophysics Data System (ADS)

Hart, John; Espeland, Brady; Bloxham, Gabe; Boz, Robert; Bundy, Dave; Davies, John; Fordham, Bart; Herald, Nick; Sharp, Rob; Vaccarella, Annino; Vest, Colin

2016-07-01

A representative range of the rotary mechanisms proposed for use in GMTIFS is described. All are driven by cryogenically rated stepper motors. For each mechanism, angular position is measured by means of eddy current sensors arranged to function as a resolver. These measure the linear displacement of a decentered aluminum alloy target in two orthogonal directions, from which angular position is determined as a function of the displacement ratio. Resolver function and performance is described. For each mechanism, the mechanical design is described and the adequacy of positioning repeatability assessed. Options for improvement are discussed.

Pump control system for windmills

DOEpatents

Avery, Don E.

1983-01-01

A windmill control system having lever means, for varying length of stroke of the pump piston, and a control means, responsive to the velocity of the wind to operate the lever means to vary the length of stroke and hence the effective displacement of the pump in accordance with available wind energy, with the control means having a sensing member separate from the windmill disposed in the wind and displaceable thereby in accordance with wind velocity.

Racking tests of non-structural building partitions (The behavior of architectural (nonstructural) building components during earthquakes)

NASA Astrophysics Data System (ADS)

Rihal, S. S.

1980-12-01

The effects of inter-story displacement (drift) during simllated earthquake conditions are reported. The correlation between inter-story relative displacement and building partition behavior, the threshold levels of partition damage, and the fundamental characteristics of non-structural building partitions (stiffness, energy absorption capacity, and strength) under horizontal racking actions were investigated. Parameters in this study consist of geometry of partition configuration and placement of gypsum wallboard panels.

A new method for testing pile by single-impact energy and P-S curve

NASA Astrophysics Data System (ADS)

Xu, Zhao-Yong; Duan, Yong-Kang; Wang, Bin; Hu, Yi-Li; Yang, Run-Hai; Xu, Jun; Zhao, Jin-Ming

2004-11-01

By studying the pile-formula and stress-wave methods ( e.g., CASE method), the authors propose a new method for testing piles using the single-impact energy and P-S curves. The vibration and wave figures are recorded, and the dynamic and static displacements are measured by different transducers near the top of piles when the pile is impacted by a heavy hammer or micro-rocket. By observing the transformation coefficient of driving energy (total energy), the consumed energy of wave motion and vibration and so on, the vertical bearing capacity for single pile is measured and calculated. Then, using the vibration wave diagram, the dynamic relation curves between the force ( P) and the displacement ( S) is calculated and the yield points are determined. Using the static-loading test, the dynamic results are checked and the relative constants of dynamic-static P-S curves are determined. Then the subsidence quantity corresponding to the bearing capacity is determined. Moreover, the shaped quality of the pile body can be judged from the formation of P-S curves.

Energy and greenhouse gas life cycle assessment and cost analysis of aerobic and anaerobic membrane bioreactor systems: Influence of scale, population density, climate, and methane recovery.

PubMed

Cashman, Sarah; Ma, Xin; Mosley, Janet; Garland, Jay; Crone, Brian; Xue, Xiaobo

2018-04-01

This study calculated the energy and greenhouse gas life cycle and cost profiles of transitional aerobic membrane bioreactors (AeMBR) and anaerobic membrane bioreactors (AnMBR). Membrane bioreactors (MBR) represent a promising technology for decentralized wastewater treatment and can produce recycled water to displace potable water. Energy recovery is possible with methane generated from AnMBRs. Scenarios for these technologies were investigated for different scale systems serving various population densities under a number of climate conditions with multiple methane recovery options. When incorporating the displacement of drinking water, AeMBRs started to realize net energy benefits at the 1 million gallons per day (MGD) scale and mesophilic AnMBRs at the 5 MGD scale. For all scales, the psychrophilic AnMBR resulted in net energy benefits. This study provides insights into key performance characteristics needed before an informed decision can be made for a community to transition towards the adoption of MBR technologies. Copyright © 2018. Published by Elsevier Ltd.

Wind, Wave, and Tidal Energy Without Power Conditioning

NASA Technical Reports Server (NTRS)

Jones, Jack A.

2013-01-01

Most present wind, wave, and tidal energy systems require expensive power conditioning systems that reduce overall efficiency. This new design eliminates power conditioning all, or nearly all, of the time. Wind, wave, and tidal energy systems can transmit their energy to pumps that send high-pressure fluid to a central power production area. The central power production area can consist of a series of hydraulic generators. The hydraulic generators can be variable displacement generators such that the RPM, and thus the voltage, remains constant, eliminating the need for further power conditioning. A series of wind blades is attached to a series of radial piston pumps, which pump fluid to a series of axial piston motors attached to generators. As the wind is reduced, the amount of energy is reduced, and the number of active hydraulic generators can be reduced to maintain a nearly constant RPM. If the axial piston motors have variable displacement, an exact RPM can be maintained for all, or nearly all, wind speeds. Analyses have been performed that show over 20% performance improvements with this technique over conventional wind turbines

A benchmark for reaction coordinates in the transition path ensemble

PubMed Central

2016-01-01

The molecular mechanism of a reaction is embedded in its transition path ensemble, the complete collection of reactive trajectories. Utilizing the information in the transition path ensemble alone, we developed a novel metric, which we termed the emergent potential energy, for distinguishing reaction coordinates from the bath modes. The emergent potential energy can be understood as the average energy cost for making a displacement of a coordinate in the transition path ensemble. Where displacing a bath mode invokes essentially no cost, it costs significantly to move the reaction coordinate. Based on some general assumptions of the behaviors of reaction and bath coordinates in the transition path ensemble, we proved theoretically with statistical mechanics that the emergent potential energy could serve as a benchmark of reaction coordinates and demonstrated its effectiveness by applying it to a prototypical system of biomolecular dynamics. Using the emergent potential energy as guidance, we developed a committor-free and intuition-independent method for identifying reaction coordinates in complex systems. We expect this method to be applicable to a wide range of reaction processes in complex biomolecular systems. PMID:27059559

Optimum Operating Conditions for PZT Actuators for Vibrotactile Wearables

NASA Astrophysics Data System (ADS)

Logothetis, Irini; Matsouka, Dimitra; Vassiliadis, Savvas; Vossou, Clio; Siores, Elias

2018-04-01

Recently, vibrotactile wearables have received much attention in fields such as medicine, psychology, athletics and video gaming. The electrical components presently used to generate vibration are rigid; hence, the design and creation of ergonomical wearables are limited. Significant advances in piezoelectric components have led to the production of flexible actuators such as piezoceramic lead zirconate titanate (PZT) film. To verify the functionality of PZT actuators for use in vibrotactile wearables, the factors influencing the electromechanical conversion were analysed and tested. This was achieved through theoretical and experimental analyses of a monomorph clamped-free structure for the PZT actuator. The research performed for this article is a three-step process. First, a theoretical analysis presents the equations governing the actuator. In addition, the eigenfrequency of the film was analysed preceding the experimental section. For this stage, by applying an electric voltage and varying the stimulating electrical characteristics (i.e., voltage, electrical waveform and frequency), the optimum operating conditions for a PZT film were determined. The tip displacement was measured referring to the mechanical energy converted from electrical energy. From the results obtained, an equation for the mechanical behaviour of PZT films as actuators was deduced. It was observed that the square waveform generated larger tip displacements. In conjunction with large voltage inputs at the predetermined eigenfrequency, the optimum operating conditions for the actuator were achieved. To conclude, PZT films can be adapted to assist designers in creating comfortable vibrotactile wearables.

Optimum Operating Conditions for PZT Actuators for Vibrotactile Wearables

NASA Astrophysics Data System (ADS)

Logothetis, Irini; Matsouka, Dimitra; Vassiliadis, Savvas; Vossou, Clio; Siores, Elias

2018-07-01

Recently, vibrotactile wearables have received much attention in fields such as medicine, psychology, athletics and video gaming. The electrical components presently used to generate vibration are rigid; hence, the design and creation of ergonomical wearables are limited. Significant advances in piezoelectric components have led to the production of flexible actuators such as piezoceramic lead zirconate titanate (PZT) film. To verify the functionality of PZT actuators for use in vibrotactile wearables, the factors influencing the electromechanical conversion were analysed and tested. This was achieved through theoretical and experimental analyses of a monomorph clamped-free structure for the PZT actuator. The research performed for this article is a three-step process. First, a theoretical analysis presents the equations governing the actuator. In addition, the eigenfrequency of the film was analysed preceding the experimental section. For this stage, by applying an electric voltage and varying the stimulating electrical characteristics (i.e., voltage, electrical waveform and frequency), the optimum operating conditions for a PZT film were determined. The tip displacement was measured referring to the mechanical energy converted from electrical energy. From the results obtained, an equation for the mechanical behaviour of PZT films as actuators was deduced. It was observed that the square waveform generated larger tip displacements. In conjunction with large voltage inputs at the predetermined eigenfrequency, the optimum operating conditions for the actuator were achieved. To conclude, PZT films can be adapted to assist designers in creating comfortable vibrotactile wearables.

The Effect of Interface Treatment on Ceramic Performance and Modeling Dyneema Subjected to Ballistic Impact

DTIC Science & Technology

2018-01-23

aluminum plate; and the time history of the aluminum back surface displacement located directly under the sphere. Figures 2-4 present the computed results... displacements as a function of time. It is clear that the computed results using no bond produce more damage in the ceramic plate and much more... displacement of the aluminum back plate. Figures 5-7 present the computed results for boron carbide (using the TR model), for impact velocities of V

An Army-Centric System of Systems Analysis (SoSA) Definition

DTIC Science & Technology

2011-02-01

1994, 19, 49–74. 34. Suzuki, K.; Ikegami , T . Homeodynamics in the Game of Life. In Artificial Life XI: Proceedings of the Eleventh International...insect displacement as a function of sampling time. (b) The same dataset displaying displacement at time t versus displacement at time t +  t ...probability distribution of x(ti), x( t i + 1), x( t i + 2), …, x( t i + m - 1) is dependent upon the value of ti (21). Similarly, a discrete time series

"State of the Art" of technical protection measures in Austria and the effectiveness documented during bedload and debris flow events

NASA Astrophysics Data System (ADS)

Moser, Markus; Mehlhorn, Susanne; Rudolf-Miklau, Florian; Suda, Jürgen

2017-04-01

Since the beginning of systematic torrent control in Austria 130 years ago, barriers are constructed for protection purposes. Until the end of the 1960s, solid barriers were built at the exits of depositional areas to prevent dangerous debris flows from reaching high consequence areas. The development of solid barriers with large slots or slits to regulate sediment transport began with the use of reinforced concrete during the 1970s (Rudolf-Miklau, Suda 2011). In order to dissipate the energy of debris flows debris flow breakers have been designed since the 1980s. By slowing and depositing the surge front of the debris flow, downstream reaches of the stream channel and settlement areas should be exposed to considerably lower dynamic impact. In the past, the technological development of these constructions was only steered by the experiences of the engineering practice while an institutionalized process of standardization comparable to other engineering branches was not existent. In future all structures have to be designed and dimensioned according to the EUROCODE standards. This was the reason to establish an interdisciplinary working group (ON-K 256) at the Austrian Standards Institute (ASI), which has managed to developed comprehensive new technical standards for torrent control engineering, including load models, design, dimensioning and life cycle assessment of torrent control works (technical standard ONR 24800 - series). Extreme torrential events comprise four definable displacement processes floods; fluvial solid transport; hyper-concentrated solid transport (debris floods) and debris flow (stony debris flow or mud-earth flow). As a rule, the design of the torrential barriers has to follow its function (Kettl, 1984). Modern protection concepts in torrent control are scenario-oriented and try to optimize different functions in a chain of protections structures (function chain). More or less the first step for the designing the optimal construction type is the definition of the displacement processes for each torrent section. The criteria for each process are defined in the technical standard ONR 24800 - series in Austria. According to ONR 24800 the functions of torrential barriers can be divided in process control functional types (retention; dosing and filtering; energy dissipation). The last step is the designing of the construction type. Bedload and debris events in Austria showed the functionality of the barriers. On the basis of these findings and results, some recommendations were derived to improve the function fulfilment of the technical protection measures.

Block structure and geodynamics of the continental lithosphere on plate boundaries

NASA Astrophysics Data System (ADS)

Gatinsky, Yu. G.; Prokhorova, T. V.; Romanyuk, T. V.; Vladova, G. L.

2009-04-01

Division of the Earth lithosphere on large plates must be considered only as the first and most general approximation in its structure hierarchy. Some transit zones or difuuse boundaries after other authors take place in lithosphere plate boundaries. The tectonic tension of plate interaction is transferred and relaxed within these zones, which consist of blocks limited by seismoactive faults. Vectors of block horizontal displacements often don't coincide with vectors of main plates and change together with changing block rigidity. As a rule the intensity the seismic energy at plate and transit zone boundaries decreases linearly with distancing from these boundaries and correlates with decreasing of velocities of block horizontal displacements. But sometimes the maximum of the energy manifestation takes place in inner parts of transit zones. Some relatively tight interblock zones established in central and east Asia are the most seismically active. They limited such blocks as Pamir, Tien Shan, Bayanhar, Shan, Japanese-Korean, as well as the north boundary of the Indian Plate. A seismic energy intensity of these zones can be compared with the energy of Pacific subduction zones. It is worthy to note that the majority catastrophic earthquakes took place in Central Asia just within interblock zones. A level of block displacement is situated mainly in the bottom or inside the Earth crust, more rare in the lithosphere mantle. Blocks with the most thick lithosphere roots (SE China, Amurian) are the most rigid and weakly deformed.

Universal behavior in ideal slip

NASA Technical Reports Server (NTRS)

Bozzolo, Guillermo; Ferrante, John; Smith, John R.

1991-01-01

The slip energies and stresses are computed for defect-free crystals of Ni, Cu, Ag, and Al using the many-atom approach. A simple analytical expression for the slip energies is obtained, leading to a universal form for slip, with the energy scaled by the surface energy and displacement scaled by the lattice constant. Maximum stresses are found to be somewhat larger than but comparable with experimentally determined maximum whisker strengths.

Capsizing Icebergs: An Exercise in the Application of the Principle of the Conservation of Energy with a Very Surprising Result

ERIC Educational Resources Information Center

Marshall, Rick

2015-01-01

Many icebergs are vulnerable to capsizing. In doing so the gravitational potential energy of the ice is increased, while that of the displaced sea water is decreased. Applying the principle of the conservation of energy shows that by capsizing, there is also a net transfer of energy to the surrounding sea water. This will be a maximum for a…

Effects of varying material properties on the load deformation characteristics of heel cushions.

PubMed

Sun, Pi-Chang; Wei, Hung-Wen; Chen, Chien-Hua; Wu, Chun-Hao; Kao, Hung-Chan; Cheng, Cheng-Kung

2008-07-01

Various insole materials were used in attenuation of heel-strike impact. This study presented a compression test to investigate the deformation characteristics of common heel cushions. There were two materials (thermoplastic elastomer "TPE" and silicone) with three hardness and six thickness being analyzed. They underwent consecutive loading-unloading cycles with a load control mode. The displacement of material thickness was recorded during cyclic compression being applied and released from 0 to 1050 N. The energy input, return and dissipation were evaluated based on the load deformation curves when new and after repeated compression. The TPE recovered more deformed energy and thickness than the silicone after the first loading cycle. The silicone would preserve more strain energy with increasing its hardness for the elastic recovery in the unloading process. The deformed energy was decreased as the original thickness did not completely recover under cyclic tests. The reduction in hysteresis area was gradually converged within 20 cycles. The silicone attenuated more impact energy in the initial cycles, but its energy dissipation was reduced after repeated loading. To increase hardness or thickness should be considered to improve resilience or accommodate persistent compression without flattening. The careful selection of cushion materials is imperative to meet individual functional demands.

Three-dimensional (3D) coseismic deformation map produced by the 2014 South Napa Earthquake estimated and modeled by SAR and GPS data integration

NASA Astrophysics Data System (ADS)

Polcari, Marco; Albano, Matteo; Fernández, José; Palano, Mimmo; Samsonov, Sergey; Stramondo, Salvatore; Zerbini, Susanna

2016-04-01

In this work we present a 3D map of coseismic displacements due to the 2014 Mw 6.0 South Napa earthquake, California, obtained by integrating displacement information data from SAR Interferometry (InSAR), Multiple Aperture Interferometry (MAI), Pixel Offset Tracking (POT) and GPS data acquired by both permanent stations and campaigns sites. This seismic event produced significant surface deformation along the 3D components causing several damages to vineyards, roads and houses. The remote sensing results, i.e. InSAR, MAI and POT, were obtained from the pair of SAR images provided by the Sentinel-1 satellite, launched on April 3rd, 2014. They were acquired on August 7th and 31st along descending orbits with an incidence angle of about 23°. The GPS dataset includes measurements from 32 stations belonging to the Bay Area Regional Deformation Network (BARDN), 301 continuous stations available from the UNAVCO and the CDDIS archives, and 13 additional campaign sites from Barnhart et al, 2014 [1]. These data constrain the horizontal and vertical displacement components proving to be helpful for the adopted integration method. We exploit the Bayes theory to search for the 3D coseismic displacement components. In particular, for each point, we construct an energy function and solve the problem to find a global minimum. Experimental results are consistent with a strike-slip fault mechanism with an approximately NW-SE fault plane. Indeed, the 3D displacement map shows a strong North-South (NS) component, peaking at about 15 cm, a few kilometers far from the epicenter. The East-West (EW) displacement component reaches its maximum (~10 cm) south of the city of Napa, whereas the vertical one (UP) is smaller, although a subsidence in the order of 8 cm on the east side of the fault can be observed. A source modelling was performed by inverting the estimated displacement components. The best fitting model is given by a ~N330° E-oriented and ~70° dipping fault with a prevailing right-lateral motion. Both NS and UP components are well constrained while the residuals for the EW component are higher. Further analysis will be mainly focused on model improvements. References [1] Barnhart W.D., Murray J.R., Yun S. H., Svarc J. L., Samsonov S. V., Fielding E. J., Brooks B. A., Milillo P. (2015) - Geodetic Constraints on the 2014 M 6.0 South Napa Earthquake. Seismological Research Letters, vol. 86, pp. 335-343, doi: http://dx.doi.org/10.1785/0220140210.

Calculation of the Displacement Current Using the Integral Form of Ampere's Law.

ERIC Educational Resources Information Center

Dahm, A. J.

1978-01-01

Derives the magnetic field as a function of position between two capacitor plates during discharge with the use of the integral form of Ampere's law and real currents only. The displacement current must be included to obtain the same result for arbitrary choices of contours. (Author/GA)

Simulation of irradiation creep

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reiley, T.C.; Jung, P.

1977-01-01

The results to date in the area of radiation enhanced deformation using beams of light ions to simulate fast neutron displacement damage are reviewed. A comparison is made between these results and those of in-reactor experiments. Particular attention is given to the displacement rate calculations for light ions and the electronic energy losses and their effect on the displacement cross section. Differences in the displacement processes for light ions and neutrons which may effect the irradiation creep process are discussed. The experimental constraints and potential problem areas associated with these experiments are compared to the advantages of simulation. Support experimentsmore » on the effect of thickness on thermal creep are presented. A brief description of the experiments in progress is presented for the following laboratories: HEDL, NRL, ORNL, PNL, U. of Lowell/MIT in the United States, AERE Harwell in the United Kingdom, CEN Saclay in France, GRK Karlsruhe and KFA Julich in West Germany.« less

Closed-form Static Analysis with Inertia Relief and Displacement-Dependent Loads Using a MSC/NASTRAN DMAP Alter

NASA Technical Reports Server (NTRS)

Barnett, Alan R.; Widrick, Timothy W.; Ludwiczak, Damian R.

1995-01-01

Solving for the displacements of free-free coupled systems acted upon by static loads is commonly performed throughout the aerospace industry. Many times, these problems are solved using static analysis with inertia relief. This solution technique allows for a free-free static analysis by balancing the applied loads with inertia loads generated by the applied loads. For some engineering applications, the displacements of the free-free coupled system induce additional static loads. Hence, the applied loads are equal to the original loads plus displacement-dependent loads. Solving for the final displacements of such systems is commonly performed using iterative solution techniques. Unfortunately, these techniques can be time-consuming and labor-intensive. Since the coupled system equations for free-free systems with displacement-dependent loads can be written in closed-form, it is advantageous to solve for the displacements in this manner. Implementing closed-form equations in static analysis with inertia relief is analogous to implementing transfer functions in dynamic analysis. Using a MSC/NASTRAN DMAP Alter, displacement-dependent loads have been included in static analysis with inertia relief. Such an Alter has been used successfully to solve efficiently a common aerospace problem typically solved using an iterative technique.

Adaptive radiotherapy for NSCLC patients: utilizing the principle of energy conservation to evaluate dose mapping operations

NASA Astrophysics Data System (ADS)

Zhong, Hualiang; Chetty, Indrin J.

2017-06-01

Tumor regression during the course of fractionated radiotherapy confounds the ability to accurately estimate the total dose delivered to tumor targets. Here we present a new criterion to improve the accuracy of image intensity-based dose mapping operations for adaptive radiotherapy for patients with non-small cell lung cancer (NSCLC). Six NSCLC patients were retrospectively investigated in this study. An image intensity-based B-spline registration algorithm was used for deformable image registration (DIR) of weekly CBCT images to a reference image. The resultant displacement vector fields were employed to map the doses calculated on weekly images to the reference image. The concept of energy conservation was introduced as a criterion to evaluate the accuracy of the dose mapping operations. A finite element method (FEM)-based mechanical model was implemented to improve the performance of the B-Spline-based registration algorithm in regions involving tumor regression. For the six patients, deformed tumor volumes changed by 21.2  ±  15.0% and 4.1  ±  3.7% on average for the B-Spline and the FEM-based registrations performed from fraction 1 to fraction 21, respectively. The energy deposited in the gross tumor volume (GTV) was 0.66 Joules (J) per fraction on average. The energy derived from the fractional dose reconstructed by the B-spline and FEM-based DIR algorithms in the deformed GTV’s was 0.51 J and 0.64 J, respectively. Based on landmark comparisons for the 6 patients, mean error for the FEM-based DIR algorithm was 2.5  ±  1.9 mm. The cross-correlation coefficient between the landmark-measured displacement error and the loss of radiation energy was  -0.16 for the FEM-based algorithm. To avoid uncertainties in measuring distorted landmarks, the B-Spline-based registrations were compared to the FEM registrations, and their displacement differences equal 4.2  ±  4.7 mm on average. The displacement differences were correlated to their relative loss of radiation energy with a cross-correlation coefficient equal to 0.68. Based on the principle of energy conservation, the FEM-based mechanical model has a better performance than the B-Spline-based DIR algorithm. It is recommended that the principle of energy conservation be incorporated into a comprehensive QA protocol for adaptive radiotherapy.

Brachial Plexus Injury in a 6-Year-Old Boy with 100% Displaced Proximal Humeral Metaphyseal Fracture: A Case Presentation.

PubMed

Jovanovich, Elizabeth Nora; Howard, James F

2017-12-01

Posttraumatic brachial plexopathies can occur following displaced proximal humeral fractures, causing profound functional deficits. Described here is an unusual case of a displaced proximal humeral metaphyseal fracture in a young child. The patient underwent closed reduction and serial casting, but hand weakness and forearm sensory loss persisted. Needle electromyography localized the injury to the mid/proximal arm near the fracture site, resulting in damage to the posterior and medial cords of the brachial plexus with profound involvement of the radial, ulnar, and median nerves and sparing of the axillary nerve. After months of occupational therapy, hand strength improved, with a nearly full return of function. V. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Non-classicality criteria: Glauber-Sudarshan P function and Mandel ? parameter

NASA Astrophysics Data System (ADS)

Alexanian, Moorad

2018-01-01

We calculate exactly the quantum mechanical, temporal Wigner quasiprobability density for a single-mode, degenerate parametric amplifier for a system in the Gaussian state, viz., a displaced-squeezed thermal state. The Wigner function allows us to calculate the fluctuations in photon number and the quadrature variance. We contrast the difference between the non-classicality criteria, which is independent of the displacement parameter ?, based on the Glauber-Sudarshan quasiprobability distribution ? and the classical/non-classical behaviour of the Mandel ? parameter, which depends strongly on ?. We find a phase transition as a function of ? such that at the critical point ?, ?, as a function of ?, goes from strictly classical, for ?, to a mixed classical/non-classical behaviour, for ?.

Effects of friction dampers on aerodynamically unstable rotor stages

NASA Technical Reports Server (NTRS)

Griffin, J. H.; Sinha, A.

1983-01-01

Attention is given to the physical concepts and mathematical techniques useful in the analysis of the stabilizing effect of friction on aerodynamically unstable rotor stages. Results are presented for three-, four-, and five-bladed disks. In the present multidegree-of-freedom model of an aerodynamically unstable rotor stage, a harmonic steady state solution due to the friction dampers may be either a stability limit, a stable cycle limit, or neither. A criterion is established in the form of an energy function which determines whether the solution is a stability limit. In the event that the initial displacement and velocity exeed those associated with the steady state solution corresponding to a stability limit, the reponse becomes unbounded.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Yanzhou; Heo, Tae Wook; Zhang, Fan

Here we present our theoretical assessment of the kinetic pathways during phase transformations of multi-component Ti alloys. Employing the graphical thermodynamic approach and an integrated free energy function based on the realistic thermodynamic database and assuming that a displacive structural transformation occurs much faster than long-range diffusional processes, we analyze the phase stabilities of Ti-6Al -4V (Ti-6wt.%Al -4wt.%V). Our systematic analyses predict a variety of possible kinetic pathways for β to (α + β) transformations leading to different types of microstructures under various heat treatment conditions. In addition, the possibility of unconventional kinetic pathways is discussed. Lastly, we also brieflymore » discuss the application of our approach to general multicomponent/multiphase alloy systems.« less

Light-Duty Vehicle Fuel Consumption Displacement Potential up to 2045

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moawad, Ayman; Rousseau, Aymeric

2016-04-01

The U.S. Department of Energy (DOE) Vehicle Technologies Program (VTP) is developing more energy-efficient and environmentally friendly highway transportation technologies that will enable America to use less petroleum. The long-term aim is to develop "leapfrog" technologies that will provide Americans with greater freedom of mobility and energy security, while lowering costs and reducing impacts on the environment.

Full-field 3D deformation measurement: comparison between speckle phase and displacement evaluation.

PubMed

Khodadad, Davood; Singh, Alok Kumar; Pedrini, Giancarlo; Sjödahl, Mikael

2016-09-20

The objective of this paper is to describe a full-field deformation measurement method based on 3D speckle displacements. The deformation is evaluated from the slope of the speckle displacement function that connects the different reconstruction planes. For our experiment, a symmetrical arrangement with four illuminations parallel to the planes (x,z) and (y,z) was used. Four sets of speckle patterns were sequentially recorded by illuminating an object from the four directions, respectively. A single camera is used to record the holograms before and after deformations. Digital speckle photography is then used to calculate relative speckle displacements in each direction between two numerically propagated planes. The 3D speckle displacements vector is calculated as a combination of the speckle displacements from the holograms recorded in each illumination direction. Using the speckle displacements, problems associated with rigid body movements and phase wrapping are avoided. In our experiment, the procedure is shown to give the theoretical accuracy of 0.17 pixels yielding the accuracy of 2×10^-3 in the measurement of deformation gradients.

Ab initio calculation of resonant Raman intensities of transition metal dichalcogenides

NASA Astrophysics Data System (ADS)

Miranda, Henrique; Reichardt, Sven; Molina-Sanchez, Alejandro; Wirtz, Ludger

Raman spectroscopy is used to characterize optical and vibrational properties of materials. Its computational simulation is important for the interpretation of experimental results. Two approaches are the bond polarizability model and density functional perturbation theory. However, both are known to not capture resonance effects. These resonances and quantum interference effects are important to correctly reproduce the intensities as a function of laser energy as, e.g., reported for the case of multi-layer MoTe21.We present two fully ab initio approaches that overcome this limitation. In the first, we calculate finite difference derivatives of the dielectric susceptibility with the phonon displacements2. In the second we calculate electron-light and electron-phonon matrix elements from density functional theory and use them to evaluate expressions for the Raman intensity derived from time-dependent perturbation theory. These expressions are implemented in a computer code that performs the calculations as a post-processing step. We compare both methods and study the case of triple-layer MoTe2. Luxembourg National Research Fund (FNR).

Factors associated with malnutrition among children in internally displaced person's camps, northern Uganda.

PubMed

Olwedo, Mary Abwola; Mworozi, Edison; Bachou, Hanifa; Orach, Christopher Garimoi

2008-12-01

Since mid 1990s, Uganda has had an estimated 1.6 million internally displaced persons (IDPs) in the northern and eastern districts. A major cause of morbidity and mortality amongst children in displaced settings is protein energy malnutrition. To estimate the prevalence of and describe the risk factors for protein energy malnutrition among under five years old children living in internally displaced persons camps in Omoro county Gulu district. This was a cross sectional study undertaken among internally displaced people's in Omoro county, Gulu district during 13 - 23(rd) September 2006. Anthropometric measurements of 672 children aged 3 - 59 months were undertaken and all their caretakers interviewed. The anthropometric measurements were analyzed using z-scores of height-for-age (H/A) and weight-for-height (W/H) indices. Qualitative data were collected through 6 focus group discussions, key informant interviews and observation. Data were captured using Epi Data version 3.0 and analyzed using EPI-INFO version 3.3.2 and SPSS version 12.0 computer packages respectively. ResultsThe prevalence of global stunting was found to be 52.4% and of global acute malnutrition 6.0%. Male children are at risk of being stunted Adjusted OR 1.57 95% CI 1.15-2.13; p value=0.004. Children in the age group 3 - 24 months were at risk of acute malnutrition Adjusted OR 2.78 95% CI 1.26-6.15; p value=0.012 while de-worming was protective Adjusted OR 0.44 95% CI 0.22-0.88; p value=0.018. The main sources of foodstuff for IDPs include food rations distributed by WFP, cultivation and purchase. There is high prevalence of protein energy malnutrition (stunting) among children in the internally displaced people's camps in Gulu district. Male children are at an increased risk of stunting while children aged between 3 - 24 months are at an increased risk of suffering from acute malnutrition. Stakeholders including local government and relief organizations should intensify efforts to improve the nutritional status of IDPs especially children in the camp settings. The quantity of and access to household food supplies, health education on infant and child feeding and integrated management of childhood illnesses (IMCI) activities in the camps should be strengthened.

In-Situ RBS Channelling Studies Of Ion Implanted Semiconductors And Insulators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wendler, E.

2011-06-01

The experimental set-up at the ion beam facility in Jena allows the performance of Rutherford backscattering spectrometry (RBS) in channeling configuration at any temperature between 15 K and room temperature without changing the environment or the temperature of the sample. Doing RBS channeling studies at 15 K increases the sensitivity to defects, because the influence of lattice vibrations is reduced. Thus, the very early processes of ion induced damage formation can be studied and the cross section of damage formation per ion in virgin material, P, can be determined. At 15 K ion-beam induced damage formation itself can be investigated,more » because the occurrence of thermal effects can be widely excluded. In AlAs, GaN, and ZnO the cross section P measured at 15 K can be used to estimate the displacement energy for the heavier component, which is in reasonable agreement with other experiments or theoretical calculations. For a given ion species (here Ar ions) the measured cross section P exhibits a quadratic dependence P{proportional_to}P{sub SRIM}{sup 2} with P{sub SRIM} being the value calculated with SRIM using established displacement energies from other sources. From these results the displacement energy of AlN can be estimated to about 40 eV. Applying the computer code DICADA to calculate the depth distribution of displaced lattice atoms from the channeling spectra, indirect information about the type of defects produced during ion implantation at 15 K can be obtained. In some materials like GaN or ZnO the results indicate the formation of extended defects most probably dislocation loops and thus suggest an athermal mobility of defect at 15 K.« less

Deformations and strains in adhesive joints by moire interferometry

NASA Technical Reports Server (NTRS)

Post, D.; Czarnek, R.; Wood, J.; John, D.; Lubowinski, S.

1984-01-01

Displacement fields in a thick adherend lap joint and a cracked lap shear specimen were measured by high sensitivity moire interferometry. Contour maps of in-plane U and V displacements were obtained across adhesive and adherent surfaces. Loading sequences ranged from modest loads to near-failure loads. Quantitative results are given for displacements and certain strains in the adhesive and along the adhesive/adherend boundary lines. The results show nonlinear displacements and strains as a function of loads or stresses and they show viscoelastic or time-dependent response. Moire interferometry is an excellent method for experimental studies of adhesive joint performance. Subwavelength displacement resolution of a few micro-inches, and spatial resolution corresponding to 1600 fringes/inch (64 fringes/mm), were obtained in these studies. The whole-field contour maps offer insights not available from local measurements made by high sensitivity gages.

Internal derangements of the temporomandibular joint: A review of the anatomy, diagnosis, and management

PubMed Central

Young, Andrew L.

2015-01-01

Internal derangements of the temporomandibular joint are conditions in which the articular disc has become displaced from its original position the condylar head. Relevant anatomic structures and their functional relationships are briefly discussed. The displacement of the disc can result in numerous presentations, with the most common being disc displacement with reduction (with or without intermittent locking), and disc displacement without reduction (with or without limited opening). These are described in this article according to the standardized Diagnostic Criteria for Temporomandibular Disorders, as well as the less common posterior disc displacement. Appropriate management usually ranges from patient education and monitoring to splints, physical therapy, and medications. In rare and select cases, surgery may be necessary. However, in for the majority of internal derangements, the prognosis is good, particularly with conservative care. PMID:26929478

Internal derangements of the temporomandibular joint: A review of the anatomy, diagnosis, and management.

PubMed

Young, Andrew L

2015-01-01

Internal derangements of the temporomandibular joint are conditions in which the articular disc has become displaced from its original position the condylar head. Relevant anatomic structures and their functional relationships are briefly discussed. The displacement of the disc can result in numerous presentations, with the most common being disc displacement with reduction (with or without intermittent locking), and disc displacement without reduction (with or without limited opening). These are described in this article according to the standardized Diagnostic Criteria for Temporomandibular Disorders, as well as the less common posterior disc displacement. Appropriate management usually ranges from patient education and monitoring to splints, physical therapy, and medications. In rare and select cases, surgery may be necessary. However, in for the majority of internal derangements, the prognosis is good, particularly with conservative care.

Compositional Effects on Electromechanical Degradation of RAINBOW Actuators

NASA Technical Reports Server (NTRS)

Dausch, David E.; Wise, Stephanie A.

1998-01-01

The effect of ceramic composition on the electromechanical displacement degradation of RAINBOW (Reduced and Internally Biased Oxide Wafer) actuators was investigated. RAINBOWs were fabricated from commercially available PZT-5H and PZT-5A piezoelectric disks as well as from tape cast PLZT piezoelectric 7/65/35 and electrostrictive 9/65/35 compositions. Displacement properties were measured at low electric fields (10 to 13 kV/cm) under loads of 0 to 500 g, and displacement degradation as a function of time was observed over 107 cycles. The PZT-5A and PLZT 9/65/35 compositions exhibited minimal decrease in displacement when load was applied. Furthermore, these compositions retained approximately 65 percent of their initial displacement after 10(exp 7) cycles under a load of 300 g. PZT-5H and PLZT 7/65/35 degraded completely under these conditions.

[Management of disk displacement with condylar fracture].

PubMed

Yu, Shi-bin; Li, Zu-bing; Yang, Xue-wen; Zhao, Ji-hong; Dong, Yao-jun

2003-07-01

To investigate clinical features of disk displacement during the course of condylar fracture and to explore the techniques of disk reposition and suturation. 32 patients (10 females and 22 males) who had disk displacements with condylar fractures were followed up. Reduction and reposition of the dislocated disks simultaneously with fixation of fractures were performed. 7 patients underwent intermaxillary fixation with elastic bands for 1 to 2 weeks. The occlusions were satisfactory in all cases but one for the reason of ramus height loss. No TMJ symptom was found when examined 3 months post operation. Anterior disk displacements were most occurred with high condylar process fractures. Surgical reposition and suturation of disk play an important role for the later TMJ-function.

Analysis of Composite Panels Subjected to Thermo-Mechanical Loads

NASA Technical Reports Server (NTRS)

Noor, Ahmed K.; Peters, Jeanne M.

1999-01-01

The results of a detailed study of the effect of cutout on the nonlinear response of curved unstiffened panels are presented. The panels are subjected to combined temperature gradient through-the-thickness combined with pressure loading and edge shortening or edge shear. The analysis is based on a first-order, shear deformation, Sanders-Budiansky-type shell theory with the effects of large displacements, moderate rotations, transverse shear deformation, and laminated anisotropic material behavior included. A mixed formulation is used with the fundamental unknowns consisting of the generalized displacements and the stress resultants of the panel. The nonlinear displacements, strain energy, principal strains, transverse shear stresses, transverse shear strain energy density, and their hierarchical sensitivity coefficients are evaluated. The hierarchical sensitivity coefficients measure the sensitivity of the nonlinear response to variations in the panel parameters, as well as in the material properties of the individual layers. Numerical results are presented for cylindrical panels and show the effects of variations in the loading and the size of the cutout on the global and local response quantities as well as their sensitivity to changes in the various panel, layer, and micromechanical parameters.

Levitation and lateral forces between a point magnetic dipole and a superconducting sphere

NASA Astrophysics Data System (ADS)

H, M. Al-Khateeb; M, K. Alqadi; F, Y. Alzoubi; B, Albiss; M, K. Hasan (Qaseer; N, Y. Ayoub

2016-05-01

The dipole-dipole interaction model is employed to investigate the angular dependence of the levitation and lateral forces acting on a small magnet in an anti-symmetric magnet/superconducting sphere system. Breaking the symmetry of the system enables us to study the lateral force which is important in the stability of the magnet above a superconducting sphere in the Meissner state. Under the assumption that the lateral displacement of the magnet is small compared to the physical dimensions of our proposed system, analytical expressions are obtained for the levitation and lateral forces as a function of the geometrical parameters of the superconductor as well as the height, the lateral displacement, and the orientation of the magnetic moment of the magnet. The dependence of the levitation force on the height of the levitating magnet is similar to that in the symmetric magnet/superconducting sphere system within the range of proposed lateral displacements. It is found that the levitation force is linearly dependent on the lateral displacement whereas the lateral force is independent of this displacement. A sinusoidal variation of both forces as a function of the polar and azimuthal angles specifying the orientation of the magnetic moment is observed. The relationship between the stability and the orientation of the magnetic moment is discussed for different orientations.

Design and analysis of fractional order seismic transducer for displacement and acceleration measurements

NASA Astrophysics Data System (ADS)

Veeraian, Parthasarathi; Gandhi, Uma; Mangalanathan, Umapathy

2018-04-01

Seismic transducers are widely used for measurement of displacement, velocity, and acceleration. This paper presents the design of seismic transducer in the fractional domain for the measurement of displacement and acceleration. The fractional order transfer function for seismic displacement and acceleration transducer are derived using Grünwald-Letnikov derivative. Frequency response analysis of fractional order seismic displacement transducer (FOSDT) and fractional order seismic acceleration transducer (FOSAT) are carried out for different damping ratio with the different fractional order, and the maximum dynamic measurement range is identified. The results demonstrate that fractional order seismic transducer has increased dynamic measurement range and less phase distortion as compared to the conventional seismic transducer even with a lower damping ratio. Time response of FOSDT and FOSAT are derived analytically in terms of Mittag-Leffler function, the effect of fractional behavior in the time domain is evaluated from the impulse and step response. The fractional order system is found to have significantly reduced overshoot as compared to the conventional transducer. The fractional order seismic transducer design proposed in this paper is illustrated with a design example for FOSDT and FOSAT. Finally, an electrical equivalent of FOSDT and FOSAT is considered, and its frequency response is found to be in close agreement with the proposed fractional order seismic transducer.

The Structural Basis of IKs Ion-Channel Activation: Mechanistic Insights from Molecular Simulations.

PubMed

Ramasubramanian, Smiruthi; Rudy, Yoram

2018-06-05

Relating ion channel (iCh) structural dynamics to physiological function remains a challenge. Current experimental and computational techniques have limited ability to explore this relationship in atomistic detail over physiological timescales. A framework associating iCh structure to function is necessary for elucidating normal and disease mechanisms. We formulated a modeling schema that overcomes the limitations of current methods through applications of artificial intelligence machine learning. Using this approach, we studied molecular processes that underlie human IKs voltage-mediated gating. IKs malfunction underlies many debilitating and life-threatening diseases. Molecular components of IKs that underlie its electrophysiological function include KCNQ1 (a pore-forming tetramer) and KCNE1 (an auxiliary subunit). Simulations, using the IKs structure-function model, reproduced experimentally recorded saturation of gating-charge displacement at positive membrane voltages, two-step voltage sensor (VS) movement shown by fluorescence, iCh gating statistics, and current-voltage relationship. Mechanistic insights include the following: 1) pore energy profile determines iCh subconductance; 2) the entire protein structure, not limited to the pore, contributes to pore energy and channel subconductance; 3) interactions with KCNE1 result in two distinct VS movements, causing gating-charge saturation at positive membrane voltages and current activation delay; and 4) flexible coupling between VS and pore permits pore opening at lower VS positions, resulting in sequential gating. The new modeling approach is applicable to atomistic scale studies of other proteins on timescales of physiological function. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Delocalization via Sliding in Solid 4He: Is It Plausible?

NASA Astrophysics Data System (ADS)

Krainyukova, N. V.

2010-02-01

The modified Debye approach was used to calculate the Gibbs free energy for solid 4He and energetic profiles for different atomic displacements with respect to an equilibrium lattice. Atoms interact via the applied Aziz potential. We have found that individual atomic displacements may hardly give rise to any delocalization because of huge barriers but cooperative plane sliding is highly plausible especially in the intermediate phase, which was found to be more favorable than hcp for small cluster sizes. In the latter case the roughness of the potential profile is less than one kelvin. In some particular sliding cases the energy levels in the nearest wells nearly coincide that is a well-known precursor for the delocalization effect.

A new magnetic coupling pump of residual pressure energy

NASA Astrophysics Data System (ADS)

Tong, Junjie; Ma, Xiaoqian; Fang, Yunhui

2017-10-01

A new method of magnetic coupling pump based on residual pressure is designed and the theoretical analysis and design calculation are carried out. The magnetic coupling pump device based on residual pressure is developed to achieve zero leakage during the energy conversion of two kinds of fluids. The results show that under the same displacement condition, the pressure head of the feed water is reduced with the increase of the feed water flow rate, the rotation speed of the axial impeller decreases gradually with the increase of the diameter of the drain pipe. In the case of the same water supply flow, the impeller speed increases with the increase of the displacement. When the available drainage increases, the pressure of the feed water supply increases.

Investigation of transition States in bulk and freestanding film polymer glasses.

PubMed

Jain, Tushar S; de Pablo, Juan J

2004-04-16

We have performed transition state searches on the potential energy landscape for bulk and freestanding film polymer glasses and identified connected minima. An analysis of the displacements between minima shows that the sites that undergo the greatest displacement are highly localized in space for both the bulk and the thin-film systems studied. In the case of the thin film, the clusters originate at the surface and penetrate into the center of the film thereby coupling the relaxation in the center of the film to the mobile surface layer. Furthermore, the energy barriers between minima are lower in the thin film than in the bulk system. These findings can rationalize the experimentally observed depression of the glass transition temperature in freestanding polymer films.

Earthquake mechanism and seafloor deformation for tsunami generation

USGS Publications Warehouse

Geist, Eric L.; Oglesby, David D.; Beer, Michael; Kougioumtzoglou, Ioannis A.; Patelli, Edoardo; Siu-Kui Au, Ivan

2014-01-01

Tsunamis are generated in the ocean by rapidly displacing the entire water column over a significant area. The potential energy resulting from this disturbance is balanced with the kinetic energy of the waves during propagation. Only a handful of submarine geologic phenomena can generate tsunamis: large-magnitude earthquakes, large landslides, and volcanic processes. Asteroid and subaerial landslide impacts can generate tsunami waves from above the water. Earthquakes are by far the most common generator of tsunamis. Generally, earthquakes greater than magnitude (M) 6.5–7 can generate tsunamis if they occur beneath an ocean and if they result in predominantly vertical displacement. One of the greatest uncertainties in both deterministic and probabilistic hazard assessments of tsunamis is computing seafloor deformation for earthquakes of a given magnitude.

Dynamic Algorithms for Transition Matrix Generation

NASA Astrophysics Data System (ADS)

Yevick, David; Lee, Yong Hwan

The methods of [D. Yevick, Int. J. Mod. Phys. C, 1650041] for constructing transition matrices are applied to the two dimensional Ising model. Decreasing the system temperature during the acquisition of the matrix elements yields a reasonably precise specific heat curve for a 32x32 spin system for a limited number (50-100M) of realizations. If the system is instead evolved to first higher and then lower energies within a restricted interval that is steadily displaced in energy as the computation proceeds, a modification which permits backward displacements up to a certain lower bound for each forward step ensures acceptable accuracy. Additional constraints on the transition rule are also investigated. The Natural Sciences and Engineering Research Council of Canada (NSERC) and CIENA are acknowledged for financial support.

Comparative study of electrical and switch-skipping mechanical switch for self-powered SSHI in medium coupled piezoelectric vibration energy harvesters

NASA Astrophysics Data System (ADS)

Asanuma, H.; Sakamoto, K.; Komatsuzaki, T.; Iwata, Y.

2018-07-01

To increase output power for piezoelectric vibration energy harvesters, considerable attention has recently been focused on a self-powered synchronized switch harvesting on inductor (SSHI) technique employing an electrical and mechanical switch. However, there are two technical issues: in a medium or highly coupled harvester, the piezoelectric coupling force, which increases as the SSHI’s voltage increases, will reduce the harvester’s displacement and the resulting output power, and there are few reports comparing the performance of electrical switch SSHI (ESS) and mechanical switch SSHI (MSS) that include consideration of the piezoelectric coupling force. We developed a simulation technique that allows us to evaluate the output power considering the piezoelectric coupling force, and investigated the performance of stopper-based MSS and ESS, both numerically and experimentally. The numerical investigation predicted the following: (1) the output power for the ESS is lower than that for the MSS at acceleration lower than 3.5 m s‑2 and (2) intriguingly, the output power for the MSS continues to increase, whereas the peak–peak displacement remains constant. The experimental results showed behaviour similar to that of the numerical predictions. The results are attributed to the different switching strategies: the MSS turns on only when the harvester’s displacement exceeds the gap distance, while the ESS turns on at every maximum/minimum displacement.

Effects of constrained arm swing on vertical center of mass displacement during walking.

PubMed

Yang, Hyung Suk; Atkins, Lee T; Jensen, Daniel B; James, C Roger

2015-10-01

The purpose of this study was to determine the effects of constraining arm swing on the vertical displacement of the body's center of mass (COM) during treadmill walking and examine several common gait variables that may account for or mask differences in the body's COM motion with and without arm swing. Participants included 20 healthy individuals (10 male, 10 female; age: 27.8 ± 6.8 years). The body's COM displacement, first and second peak vertical ground reaction forces (VGRFs), and lowest VGRF during mid-stance, peak summed bilateral VGRF, lower extremity sagittal joint angles, stride length, and foot contact time were measured with and without arm swing during walking at 1.34 m/s. The body's COM displacement was greater with the arms constrained (arm swing: 4.1 ± 1.2 cm, arm constrained: 4.9 ± 1.2 cm, p < 0.001). Ground reaction force data indicated that the COM displacement increased in both double limb and single limb stance. However, kinematic patterns visually appeared similar between conditions. Shortened stride length and foot contact time also were observed, although these do not seem to account for the increased COM displacement. However, a change in arm COM acceleration might have contributed to the difference. These findings indicate that a change in arm swing causes differences in vertical COM displacement, which could increase energy expenditure. Copyright © 2015 Elsevier B.V. All rights reserved.

Wettability and Flow Rate Impacts on Immiscible Displacement: A Theoretical Model

NASA Astrophysics Data System (ADS)

Hu, Ran; Wan, Jiamin; Yang, Zhibing; Chen, Yi-Feng; Tokunaga, Tetsu

2018-04-01

When a more viscous fluid displaces a less viscous one in porous media, viscous pressure drop stabilizes the displacement front against capillary pressure fluctuation. For this favorable viscous ratio conditions, previous studies focused on the front instability under slow flow conditions but did not address competing effects of wettability and flow rate. Here we study how this competition controls displacement patterns. We propose a theoretical model that describes the crossover from fingering to stable flow as a function of invading fluid contact angle θ and capillary number Ca. The phase diagram predicted by the model shows that decreasing θ stabilizes the displacement for θ≥45° and the critical contact angle θc increases with Ca. The boundary between corner flow and cooperative filling for θ < 45° is also described. This work extends the classic phase diagram and has potential applications in predicting CO2 capillary trapping and manipulating wettability to enhance gas/oil displacement efficiency.

Correlation of electron and proton irradiation-induced damage in InP solar cells

NASA Technical Reports Server (NTRS)

Walters, Robert J.; Summers, Geoffrey P.; Messenger, Scott R.; Burke, Edward A.

1995-01-01

When determining the best solar cell technology for a particular space flight mission, accurate prediction of solar cell performance in a space radiation environment is essential. The current methodology used to make such predictions requires extensive experimental data measured under both electron and proton irradiation. Due to the rising cost of accelerators and irradiation facilities, such extensive data sets are expensive to obtain. Moreover, with the rapid development of novel cell designs, the necessary data are often not available. Therefore, a method for predicting cell degradation based on limited data is needed. Such a method has been developed at the Naval Research Laboratory based on damage correlation using 'displacement damage dose' which is the product of the non-ionizing energy loss (NIEL) and the particle fluence. Displacement damage dose is a direct analog of the ionization dose used to correlate the effects of ionizing radiations. In this method, the performance of a solar cell in a complex radiation environment can be predicted from data on a single proton energy and two electron energies, or one proton energy, one electron energy, and Co(exp 60) gammas. This method has been used to accurately predict the extensive data set measured by Anspaugh on GaAs/Ge solar cells under a wide range of electron and proton energies. In this paper, the method is applied to InP solar cells using data measured under 1 MeV electron and 3 MeV proton irradiations, and the calculations are shown to agree well with the measured data. In addition to providing accurate damage predictions, this method also provides a basis for quantitative comparisons of the performance of different cell technologies. The performance of the present InP cells is compared to that published for GaAs/Ge cells. The results show InP to be inherently more resistant to displacement energy deposition than GaAs/Ge.

Induced Fit in Protein Multimerization: The HFBI Case

PubMed Central

Riccardi, Laura

2016-01-01

Hydrophobins, produced by filamentous fungi, are small amphipathic proteins whose biological functions rely on their unique surface-activity properties. Understanding the mechanistic details of the multimerization process is of primary importance to clarify the interfacial activity of hydrophobins. We used free energy calculations to study the role of a flexible β-hairpin in the multimerization process in hydrophobin II from Trichoderma reesei (HFBI). We characterized how the displacement of this β-hairpin controls the stability of the monomers/dimers/tetramers in solution. The regulation of the oligomerization equilibrium of HFBI will necessarily affect its interfacial properties, fundamental for its biological function and for technological applications. Moreover, we propose possible routes for the multimerization process of HFBI in solution. This is the first case where a mechanism by which a flexible loop flanking a rigid patch controls the protein-protein binding equilibrium, already known for proteins with charged binding hot-spots, is described within a hydrophobic patch. PMID:27832079

Study of vibrational modes in CuxAg1-xIn5S8 mixed crystals by infrared reflection measurements

NASA Astrophysics Data System (ADS)

Gasanly, N. M.

2018-04-01

Infrared reflection spectra of CuxAg1-xIn5S8 mixed crystals, grown by Bridgman method, were studied in the wide frequency range of 50-2000 cm-1. All four infrared-active modes were detected, which are in full agreement with the prediction of group-theoretical analysis. Real and imaginary parts of the dielectric function, refractive index and the energy losses function were evaluated from reflectivity measurements. The frequencies of TO and LO modes and oscillator strengths were also determined. The bands detected in IR spectra of studied crystals were assigned to various vibration types (valence and valence-deformation) on the basis of the symmetrized displacements of atoms obtained employing the Melvin projection operators. The linear dependencies of optical mode frequencies on the composition of CuxAg1-xIn5S8 mixed crystals were obtained. These dependencies display one-mode behavior.

Displacement cascades and defect annealing in tungsten, Part II: Object kinetic Monte Carlo Simulation of Tungsten Cascade Aging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.

2015-07-01

The results of object kinetic Monte Carlo (OKMC) simulations of the annealing of primary cascade damage in bulk tungsten using a comprehensive database of cascades obtained from molecular dynamics (Setyawan et al.) are described as a function of primary knock-on atom (PKA) energy at temperatures of 300, 1025 and 2050 K. An increase in SIA clustering coupled with a decrease in vacancy clustering with increasing temperature, in addition to the disparate mobilities of SIAs versus vacancies, causes an interesting effect of temperature on cascade annealing. The annealing efficiency (the ratio of the number of defects after and before annealing) exhibitsmore » an inverse U-shape curve as a function of temperature. The capabilities of the newly developed OKMC code KSOME (kinetic simulations of microstructure evolution) used to carry out these simulations are described.« less

Injury tolerance and moment response of the knee joint to combined valgus bending and shear loading.

PubMed

Bose, Dipan; Bhalla, Kavi S; Untaroiu, Costin D; Ivarsson, B Johan; Crandall, Jeff R; Hurwitz, Shepard

2008-06-01

Valgus bending and shearing of the knee have been identified as primary mechanisms of injuries in a lateral loading environment applicable to pedestrian-car collisions. Previous studies have reported on the structural response of the knee joint to pure valgus bending and lateral shearing, as well as the estimated injury thresholds for the knee bending angle and shear displacement based on experimental tests. However, epidemiological studies indicate that most knee injuries are due to the combined effects of bending and shear loading. Therefore, characterization of knee stiffness for combined loading and the associated injury tolerances is necessary for developing vehicle countermeasures to mitigate pedestrian injuries. Isolated knee joint specimens (n=40) from postmortem human subjects were tested in valgus bending at a loading rate representative of a pedestrian-car impact. The effect of lateral shear force combined with the bending moment on the stiffness response and the injury tolerances of the knee was concurrently evaluated. In addition to the knee moment-angle response, the bending angle and shear displacement corresponding to the first instance of primary ligament failure were determined in each test. The failure displacements were subsequently used to estimate an injury threshold function based on a simplified analytical model of the knee. The validity of the determined injury threshold function was subsequently verified using a finite element model. Post-test necropsy of the knees indicated medial collateral ligament injury consistent with the clinical injuries observed in pedestrian victims. The moment-angle response in valgus bending was determined at quasistatic and dynamic loading rates and compared to previously published test data. The peak bending moment values scaled to an average adult male showed no significant change with variation in the superimposed shear load. An injury threshold function for the knee in terms of bending angle and shear displacement was determined by performing regression analysis on the experimental data. The threshold values of the bending angle (16.2 deg) and shear displacement (25.2 mm) estimated from the injury threshold function were in agreement with previously published knee injury threshold data. The continuous knee injury function expressed in terms of bending angle and shear displacement enabled injury prediction for combined loading conditions such as those observed in pedestrian-car collisions.

Repair of lesser tuberosity osteotomy for shoulder arthroplasty: biomechanical evaluation of the Backpack and Dual Row techniques.

PubMed

Heckman, Daniel S; Hoover, Stephen A; Weinhold, Paul S; Spang, Jeffrey T; Creighton, R Alexander

2011-04-01

Subscapularis dysfunction following total shoulder arthroplasty can result in permanent loss of function. The lesser tuberosity osteotomy (LTO) has been proposed as a method which utilizes bone-to-bone healing to improve subscapularis function. This study evaluates the biomechanical properties of two described techniques for LTO repair. We hypothesized that a Dual Row repair would be stronger and demonstrate less cyclic displacement than a Backpack repair. Ten matched pairs of cadaveric humeri were dissected, leaving the subscapularis intact, and a lesser tuberosity osteotomy was performed. Matched shoulders were randomized to either a Backpack repair or a Dual Row repair. Repairs were subjected to cyclic loading to 180 N for 500 cycles, followed by ramp-up loading to ultimate failure. Clinical failure was defined as displacement >5 mm after 500 cycles. Displacement after 500 cycles was significantly greater for the Backpack repair (6.9 mm) than for the Dual Row repair (4.6 mm) (P = .007). Most displacement occurred on the first cycle (Backpack, 4.6 mm; Dual Row, 2.1 mm) (P < .001). There was a trend toward a higher clinical failure rate for the Backpack repair (8/10) than the Dual Row repair (3/10). Ultimate tensile strength was significantly greater for the Dual Row repair (632.3 N) than for the Backpack repair (510.9 N) (P = .01). The Dual Row technique is significantly stronger and demonstrates less cyclic displacement than the Backpack technique. Clinical studies are needed to determine the impact of LTO repair technique on subscapularis function following shoulder arthroplasty. Copyright © 2011. Published by Mosby, Inc.

Experimental and Numerical Analysis of Axially Compressed Circular Cylindrical Fiber-Reinforced Panels with Various Boundary Conditions.

DTIC Science & Technology

1981-10-01

Numerical predictions used in the compari- sons were obtained from the energy -based, finite-difference computer proqram CLAPP. Test specimens were clamped...edges V LONGITUDINAL STIFFENERS 45 I. Introduction 45 2. Stiffener Strain Energy 46 3. Stiffener Energy in Matrix Form 47 4. Displacement Continuity 49...that theoretical bifurcation loads predicted by the energy method represent upper bounds to the classical bifurcation loads associated with the test

A Crude Reality; Exploring the Interdependencies of Energy (Oil), the Macro-Economy, and National Security

DTIC Science & Technology

2012-04-11

Policy (SWEEP) optimizing our own natural resources in the near term (oil, natural gas, coal, nuclear, wind, solar, hydro, geothermal and synthetics... geothermal and synthetics), and displaces the oil based economy with a long term energy transformation plan based on renewable energy, is vital to...climb and supply begins to diminish. Global energy demands will continue to rise as the developing economies of countries like Brazil, Russia, China

Large-Deformation Displacement Transfer Functions for Shape Predictions of Highly Flexible Slender Aerospace Structures

NASA Technical Reports Server (NTRS)

Ko, William L.; Fleischer, Van Tran

2013-01-01

Large deformation displacement transfer functions were formulated for deformed shape predictions of highly flexible slender structures like aircraft wings. In the formulation, the embedded beam (depth wise cross section of structure along the surface strain sensing line) was first evenly discretized into multiple small domains, with surface strain sensing stations located at the domain junctures. Thus, the surface strain (bending strains) variation within each domain could be expressed with linear of nonlinear function. Such piecewise approach enabled piecewise integrations of the embedded beam curvature equations [classical (Eulerian), physical (Lagrangian), and shifted curvature equations] to yield closed form slope and deflection equations in recursive forms.

Dietary fiber does not displace energy but is associated with decreased serum cholesterol concentrations in healthy children.

PubMed

Ruottinen, Soile; Lagström, Hanna K; Niinikoski, Harri; Rönnemaa, Tapani; Saarinen, Maiju; Pahkala, Katja A; Hakanen, Maarit; Viikari, Jorma Sa; Simell, Olli

2010-03-01

Dietary fiber has health benefits, but fiber recommendations for children are controversial because fiber may displace energy. The objective was to longitudinally evaluate dietary fiber intake in children and to study associations between growth variables, serum cholesterol concentrations, and intakes of fiber, energy, and nutrients. Altogether, 543 children from a prospective randomized atherosclerosis prevention trial (the Special Turku Coronary Risk factor Intervention Project; STRIP) participated in this study between the ages of 8 mo and 9 y. The intervention children (n = 264) were counseled to replace part of saturated fat with unsaturated fat. Nutrient intakes, weight, height, and serum total, HDL-, and LDL-cholesterol and triglyceride concentrations were analyzed. Children were divided into 3 groups according to mean dietary fiber intake in foods: low (lowest 10%), high (highest 10%), and average (middle 80%) fiber intakes. Fiber intake associated positively with energy intake and inversely with fat intake. Children with a high fiber intake received more vitamins and minerals than did children in other groups. In longitudinal growth analyses, weights and heights were similar in all 3 fiber intake groups, and fiber intake (g/d) associated positively with weight gain between 8 mo and 2 y. Serum cholesterol concentrations decreased with increasing fiber intakes. Children in the intervention group had a higher fiber intake than did the control children during the entire follow-up period. Fiber intake did not displace energy or disturb growth between 13 mo and 9 y of age. Serum cholesterol values correlated inversely with fiber intake, which indicated that part of the cholesterol-lowering intervention effect in the STRIP project may have been explained by dietary fiber.

Thermodynamic stability in elastic systems: Hard spheres embedded in a finite spherical elastic solid.

PubMed

Solano-Altamirano, J M; Goldman, Saul

2015-12-01

We determined the total system elastic Helmholtz free energy, under the constraints of constant temperature and volume, for systems comprised of one or more perfectly bonded hard spherical inclusions (i.e. "hard spheres") embedded in a finite spherical elastic solid. Dirichlet boundary conditions were applied both at the surface(s) of the hard spheres, and at the outer surface of the elastic solid. The boundary conditions at the surface of the spheres were used to describe the rigid displacements of the spheres, relative to their initial location(s) in the unstressed initial state. These displacements, together with the initial positions, provided the final shape of the strained elastic solid. The boundary conditions at the outer surface of the elastic medium were used to ensure constancy of the system volume. We determined the strain and stress tensors numerically, using a method that combines the Neuber-Papkovich spherical harmonic decomposition, the Schwartz alternating method, and Least-squares for determining the spherical harmonic expansion coefficients. The total system elastic Helmholtz free energy was determined by numerically integrating the elastic Helmholtz free energy density over the volume of the elastic solid, either by a quadrature, or a Monte Carlo method, or both. Depending on the initial position of the hard sphere(s) (or equivalently, the shape of the un-deformed stress-free elastic solid), and the displacements, either stationary or non-stationary Helmholtz free energy minima were found. The non-stationary minima, which involved the hard spheres nearly in contact with one another, corresponded to lower Helmholtz free energies, than did the stationary minima, for which the hard spheres were further away from one another.

Refined hierarchical kinematics quasi-3D Ritz models for free vibration analysis of doubly curved FGM shells and sandwich shells with FGM core

NASA Astrophysics Data System (ADS)

Fazzolari, Fiorenzo A.; Carrera, Erasmo

2014-02-01

In this paper, the Ritz minimum energy method, based on the use of the Principle of Virtual Displacements (PVD), is combined with refined Equivalent Single Layer (ESL) and Zig Zag (ZZ) shell models hierarchically generated by exploiting the use of Carrera's Unified Formulation (CUF), in order to engender the Hierarchical Trigonometric Ritz Formulation (HTRF). The HTRF is then employed to carry out the free vibration analysis of doubly curved shallow and deep functionally graded material (FGM) shells. The PVD is further used in conjunction with the Gauss theorem to derive the governing differential equations and related natural boundary conditions. Donnell-Mushtari's shallow shell-type equations are given as a particular case. Doubly curved FGM shells and doubly curved sandwich shells made up of isotropic face sheets and FGM core are investigated. The proposed shell models are widely assessed by comparison with the literature results. Two benchmarks are provided and the effects of significant parameters such as stacking sequence, boundary conditions, length-to-thickness ratio, radius-to-length ratio and volume fraction index on the circular frequency parameters and modal displacements are discussed.

Biomimetics of [NiFe]-Hydrogenase: Nickel- or Iron-Centered Proton Reduction Catalysis?

PubMed

Tang, Hao; Hall, Michael B

2017-12-13

The [NiFe] hydrogenase (H2ase) has been characterized in the Ni-R state with a hydride bridging between Fe and Ni but displaced toward the Ni. In nearly all of the synthetic Ni-R models reported so far, the hydride ligand is either displaced toward Fe, or terminally bound to Fe. Recently, a structural and functional [NiFe]-H2ase mimic ( Nat. Chem. 2016 , 8 , 1054 - 1060 ) was reported to produce H 2 catalytically via EECC mechanism through a Ni-centered hydride intermediate like the enzyme. Here, a comprehensive DFT study shows a much lower energy route via an E[ECEC] mechanism through an Fe-centered hydride intermediate. Although catalytic H 2 production occurs at the potential corresponding to the complex's second reduction, a third electron is needed to induce the second proton addition from the weak acid. The first two-electron reductions and a proton addition produce a semibridging hydride with a short Fe-H bond like other structured [NiFe]-biomimetics, but this species is not basic enough to add another proton from the weak acid without the third electron. The calculated mechanism provides insight into the origin of this structure in the enzyme.

Thermal conductivity of self-ion irradiated nanocrystalline zirconium thin films

DOE PAGES

Pulavarthy, Raghu; Wang, Baoming; Hattar, Khalid; ...

2017-07-15

Thermomechanical stability and high thermal conductivity are important for nuclear cladding material performance and reliability, which degrade over time under irradiation. The literature suggests nanocrystalline materials as radiation tolerant, but little or no evidence is present from thermal transport perspective. In this study, we irradiated 10 nm grain size zirconium thin films with 800 keV Zr + beam from a 6 MV HVE Tandem accelerator to achieve various doses of 3 × 10 10 to 3.26 × 10 14 ions/cm 2, corresponding to displacement per atom (dpa) of 2.1 × 10 –4 to 2.28. Transmission electron microscopy showed significant grainmore » growth, texture evolution and oxidation in addition to the creation of displacement defects due to the irradiation. The specimens were co-fabricated with micro-heaters to establish thermal gradients that were mapped using infrared thermometry. An energy balance approach was used to estimate the thermal conductivity of the specimens, as function of irradiation dosage. As a result, up to 32% reduction of thermal conductivity was measured for the sample exposed to a dose of 2.1 dpa (3 × 10 14 ions/cm 2).« less

Noble-transition metal nanoparticle breathing in a reactive gas atmosphere.

PubMed

Petkov, Valeri; Shan, Shiyao; Chupas, Peter; Yin, Jun; Yang, Lefu; Luo, Jin; Zhong, Chuan-Jian

2013-08-21

In situ high-energy X-ray diffraction coupled to atomic pair distribution function analysis is used to obtain fundamental insight into the effect of the reactive gas environment on the atomic-scale structure of metallic particles less than 10 nm in size. To substantiate our recent discovery we investigate a wide range of noble-transition metal nanoparticles and confirm that they expand and contract radially when treated in oxidizing (O2) and reducing (H2) atmospheres, respectively. The results are confirmed by supplementary XAFS experiments. Using computer simulations guided by the experimental diffraction data we quantify the effect in terms of both relative lattice strain and absolute atomic displacements. In particular, we show that the effect leads to a small percent of extra surface strain corresponding to several tenths of Ångström displacements of the atoms at the outmost layer of the particles. The effect then gradually decays to zero within 4 atomic layers inside the particles. We also show that, reminiscent of a breathing type structural transformation, the effect is reproducible and reversible. We argue that because of its significance and widespread occurrence the effect should be taken into account in nanoparticle research.

Atomic motion from the mean square displacement in a monatomic liquid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wallace, Duane C.; De Lorenzi-Venneri, Giulia; Chisolm, Eric D.

V-T theory is constructed in the many-body Hamiltonian formulation, and is being developed as a novel approach to liquid dynamics theory. In this theory the liquid atomic motion consists of two contributions, normal mode vibrations in a single representative potential energy valley, and transits, which carry the system across boundaries between valleys. The mean square displacement time correlation function (the MSD) is a direct measure of the atomic motion, and our goal is to determine if the V-T formalism can produce a physically sensible account of this motion. We employ molecular dynamics (MD) data for a system representing liquid Na,more » and find the motion evolves in three successive time intervals: on the first 'vibrational' interval, the vibrational motion alone gives a highly accurate account of the MD data; on the second 'crossover' interval, the vibrational MSD saturates to a constant while the transit motion builds up from zero; on the third 'random walk' interval, the transit motion produces a purely diffusive random walk of the vibrational equilibrium positions. Furthermore, this motional evolution agrees with, and adds refinement to, the MSD atomic motion as described by current liquid dynamics theories.« less

Atomic motion from the mean square displacement in a monatomic liquid

DOE PAGES

Wallace, Duane C.; De Lorenzi-Venneri, Giulia; Chisolm, Eric D.

2016-04-08

V-T theory is constructed in the many-body Hamiltonian formulation, and is being developed as a novel approach to liquid dynamics theory. In this theory the liquid atomic motion consists of two contributions, normal mode vibrations in a single representative potential energy valley, and transits, which carry the system across boundaries between valleys. The mean square displacement time correlation function (the MSD) is a direct measure of the atomic motion, and our goal is to determine if the V-T formalism can produce a physically sensible account of this motion. We employ molecular dynamics (MD) data for a system representing liquid Na,more » and find the motion evolves in three successive time intervals: on the first 'vibrational' interval, the vibrational motion alone gives a highly accurate account of the MD data; on the second 'crossover' interval, the vibrational MSD saturates to a constant while the transit motion builds up from zero; on the third 'random walk' interval, the transit motion produces a purely diffusive random walk of the vibrational equilibrium positions. Furthermore, this motional evolution agrees with, and adds refinement to, the MSD atomic motion as described by current liquid dynamics theories.« less

Modeling of a viscoelastic damper and its application in structural control

PubMed Central

Ibrahim, Zainah; Ghodsi, S. S.; Khatibi, Hamed

2017-01-01

Conventional seismic rehabilitation methods may not be suitable for some buildings owing to their high cost and time-consuming foundation work. In recent years, viscoelastic dampers (VEDs) have been widely used in many mid- and high-rise buildings. This study introduces a viscoelastic passive control system called rotary rubber braced damper (RRBD). The RRBD is an economical, lightweight, and easy-to-assemble device. A finite element model considering nonlinearity, large deformation, and material damage is developed to conduct a parametric study on different damper sizes under pushover cyclic loading. The fundamental characteristics of this VED system are clarified by analyzing building structures under cyclic loading. The result show excellent energy absorption and stable hysteresis loops in all specimens. Additionally, by using a sinusoidal shaking table test, the effectiveness of the RRBD to manage the response displacement and acceleration of steel frames is considered. The RRBD functioned at early stages of lateral displacement, indicating that the system is effective for all levels of vibration. Moreover, the proposed damper shows significantly better performance in terms of the column compression force resulting from the brace action compared to chevron bracing (CB). PMID:28570657

Thermal conductivity of self-ion irradiated nanocrystalline zirconium thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pulavarthy, Raghu; Wang, Baoming; Hattar, Khalid

Thermomechanical stability and high thermal conductivity are important for nuclear cladding material performance and reliability, which degrade over time under irradiation. The literature suggests nanocrystalline materials as radiation tolerant, but little or no evidence is present from thermal transport perspective. In this study, we irradiated 10 nm grain size zirconium thin films with 800 keV Zr + beam from a 6 MV HVE Tandem accelerator to achieve various doses of 3 × 10 10 to 3.26 × 10 14 ions/cm 2, corresponding to displacement per atom (dpa) of 2.1 × 10 –4 to 2.28. Transmission electron microscopy showed significant grainmore » growth, texture evolution and oxidation in addition to the creation of displacement defects due to the irradiation. The specimens were co-fabricated with micro-heaters to establish thermal gradients that were mapped using infrared thermometry. An energy balance approach was used to estimate the thermal conductivity of the specimens, as function of irradiation dosage. As a result, up to 32% reduction of thermal conductivity was measured for the sample exposed to a dose of 2.1 dpa (3 × 10 14 ions/cm 2).« less

Bioinspired model of mechanical energy harvesting based on flexoelectric membranes.

PubMed

Rey, Alejandro D; Servio, P; Herrera-Valencia, E E

2013-02-01

Membrane flexoelectricity is an electromechanical coupling process that describes membrane electrical polarization due to bending and membrane bending under electric fields. In this paper we propose, formulate, and characterize a mechanical energy harvesting system consisting of a deformable soft flexoelectric thin membrane subjected to harmonic forcing from contacting bulk fluids. The key elements of the energy harvester are formulated and characterized, including (i) the mechanical-to-electrical energy conversion efficiency, (ii) the electromechanical shape equation connecting fluid forces with membrane curvature and electric displacement, and (iii) the electric power generation and efficiency. The energy conversion efficiency is cast as the ratio of flexoelectric coupling to the product of electric and bending elasticity. The device is described by a second-order curvature dynamics coupled to the electric displacement equation and as such results in mechanical power absorption with a resonant peak whose amplitude decreases with bending viscosity. The electric power generation is proportional to the conversion factor and the power efficiency decreases with frequency. Under high bending viscosity, the power efficiency increases with the conversion factor and under low viscosities it decreases with the conversion factor. The theoretical results presented contribute to the ongoing experimental efforts to develop mechanical energy harvesting from fluid flow energy through solid-fluid interactions and electromechanical transduction.

Can the ionosphere regulate magnetospheric convection.

NASA Technical Reports Server (NTRS)

Coroniti, F. V.; Kennel, C. F.

1973-01-01

A simple model is outlined that relates the dayside magnetopause displacement to the currents feeding the polar cap ionosphere, from which the ionospheric electric field and the flux return rate may be estimated as a function of magnetopause displacement. Then, flux conservation arguments make possible an estimate of the time scale on which convection increases.

Effects of translation-rotation coupling on the displacement probability distribution functions of boomerang colloidal particles

NASA Astrophysics Data System (ADS)

Chakrabarty, Ayan; Wang, Feng; Sun, Kai; Wei, Qi-Huo

Prior studies have shown that low symmetry particles such as micro-boomerangs exhibit behaviour of Brownian motion rather different from that of high symmetry particles because convenient tracking points (TPs) are usually inconsistent with the center of hydrodynamic stress (CoH) where the translational and rotational motions are decoupled. In this paper we study the effects of the translation-rotation coupling on the displacement probability distribution functions (PDFs) of the boomerang colloid particles with symmetric arms. By tracking the motions of different points on the particle symmetry axis, we show that as the distance between the TP and the CoH is increased, the effects of translation-rotation coupling becomes pronounced, making the short-time 2D PDF for fixed initial orientation to change from elliptical to crescent shape and the angle averaged PDFs from ellipsoidal-particle-like PDF to a shape with a Gaussian top and long displacement tails. We also observed that at long times the PDFs revert to Gaussian. This crescent shape of 2D PDF provides a clear physical picture of the non-zero mean displacements observed in boomerangs particles.

The effect of shape on the fracture of a soft elastic gel subjected to shear load.

PubMed

Kundan, Krishna Kant; Ghatak, Animangsu

2018-02-21

For brittle solids, the fracture energy is the energy required to create a unit area of new surface through the process of division. For crosslinked materials, it is a function of the intrinsic properties like crosslinking density and bond strength of the crosslinks. Here we show that the energy released due to fracture can depend also on the shape of a joint made of this material. Our experiment involves two gel blocks connected via a thin gel disk. The disk is formed into different regular and exotic shapes, but with identical areas of cross-section. When one of the blocks is sheared with respect to the other, the shear load increases with vertical displacement, eventually causing a fracture at a threshold load. The maximum fracture load is different for different disks and among different regularly shaped disks, it is at a maximum for pentagon and hexagon shapes. The fracture energy release rate of the joint depends also on the aspect ratio (height/width) of the shapes. Our experiments also throw light on possible reasons for such a dependence on the shape of the joints.

Fast mean and variance computation of the diffuse sound transmission through finite-sized thick and layered wall and floor systems

NASA Astrophysics Data System (ADS)

Decraene, Carolina; Dijckmans, Arne; Reynders, Edwin P. B.

2018-05-01

A method is developed for computing the mean and variance of the diffuse field sound transmission loss of finite-sized layered wall and floor systems that consist of solid, fluid and/or poroelastic layers. This is achieved by coupling a transfer matrix model of the wall or floor to statistical energy analysis subsystem models of the adjacent room volumes. The modal behavior of the wall is approximately accounted for by projecting the wall displacement onto a set of sinusoidal lateral basis functions. This hybrid modal transfer matrix-statistical energy analysis method is validated on multiple wall systems: a thin steel plate, a polymethyl methacrylate panel, a thick brick wall, a sandwich panel, a double-leaf wall with poro-elastic material in the cavity, and a double glazing. The predictions are compared with experimental data and with results obtained using alternative prediction methods such as the transfer matrix method with spatial windowing, the hybrid wave based-transfer matrix method, and the hybrid finite element-statistical energy analysis method. These comparisons confirm the prediction accuracy of the proposed method and the computational efficiency against the conventional hybrid finite element-statistical energy analysis method.

Grid inhomogeneous solvation theory: hydration structure and thermodynamics of the miniature receptor cucurbit[7]uril.

PubMed

Nguyen, Crystal N; Young, Tom Kurtzman; Gilson, Michael K

2012-07-28

The displacement of perturbed water upon binding is believed to play a critical role in the thermodynamics of biomolecular recognition, but it is nontrivial to unambiguously define and answer questions about this process. We address this issue by introducing grid inhomogeneous solvation theory (GIST), which discretizes the equations of inhomogeneous solvation theory (IST) onto a three-dimensional grid situated in the region of interest around a solute molecule or complex. Snapshots from explicit solvent simulations are used to estimate localized solvation entropies, energies, and free energies associated with the grid boxes, or voxels, and properly summing these thermodynamic quantities over voxels yields information about hydration thermodynamics. GIST thus provides a smoothly varying representation of water properties as a function of position, rather than focusing on hydration sites where solvent is present at high density. It therefore accounts for full or partial displacement of water from sites that are highly occupied by water, as well as for partly occupied and water-depleted regions around the solute. GIST can also provide a well-defined estimate of the solvation free energy and therefore enables a rigorous end-states analysis of binding. For example, one may not only use a first GIST calculation to project the thermodynamic consequences of displacing water from the surface of a receptor by a ligand, but also account, in a second GIST calculation, for the thermodynamics of subsequent solvent reorganization around the bound complex. In the present study, a first GIST analysis of the molecular host cucurbit[7]uril is found to yield a rich picture of hydration structure and thermodynamics in and around this miniature receptor. One of the most striking results is the observation of a toroidal region of high water density at the center of the host's nonpolar cavity. Despite its high density, the water in this toroidal region is disfavored energetically and entropically, and hence may contribute to the known ability of this small receptor to bind guest molecules with unusually high affinities. Interestingly, the toroidal region of high water density persists even when all partial charges of the receptor are set to zero. Thus, localized regions of high solvent density can be generated in a binding site without strong, attractive solute-solvent interactions.

Grid inhomogeneous solvation theory: Hydration structure and thermodynamics of the miniature receptor cucurbit[7]uril

PubMed Central

Nguyen, Crystal N.; Kurtzman Young, Tom; Gilson, Michael K.

2012-01-01

The displacement of perturbed water upon binding is believed to play a critical role in the thermodynamics of biomolecular recognition, but it is nontrivial to unambiguously define and answer questions about this process. We address this issue by introducing grid inhomogeneous solvation theory (GIST), which discretizes the equations of inhomogeneous solvation theory (IST) onto a three-dimensional grid situated in the region of interest around a solute molecule or complex. Snapshots from explicit solvent simulations are used to estimate localized solvation entropies, energies, and free energies associated with the grid boxes, or voxels, and properly summing these thermodynamic quantities over voxels yields information about hydration thermodynamics. GIST thus provides a smoothly varying representation of water properties as a function of position, rather than focusing on hydration sites where solvent is present at high density. It therefore accounts for full or partial displacement of water from sites that are highly occupied by water, as well as for partly occupied and water-depleted regions around the solute. GIST can also provide a well-defined estimate of the solvation free energy and therefore enables a rigorous end-states analysis of binding. For example, one may not only use a first GIST calculation to project the thermodynamic consequences of displacing water from the surface of a receptor by a ligand, but also account, in a second GIST calculation, for the thermodynamics of subsequent solvent reorganization around the bound complex. In the present study, a first GIST analysis of the molecular host cucurbit[7]uril is found to yield a rich picture of hydration structure and thermodynamics in and around this miniature receptor. One of the most striking results is the observation of a toroidal region of high water density at the center of the host's nonpolar cavity. Despite its high density, the water in this toroidal region is disfavored energetically and entropically, and hence may contribute to the known ability of this small receptor to bind guest molecules with unusually high affinities. Interestingly, the toroidal region of high water density persists even when all partial charges of the receptor are set to zero. Thus, localized regions of high solvent density can be generated in a binding site without strong, attractive solute-solvent interactions. PMID:22852591

Quantum dynamics of a plane pendulum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leibscher, Monika; Schmidt, Burkhard

A semianalytical approach to the quantum dynamics of a plane pendulum is developed, based on Mathieu functions which appear as stationary wave functions. The time-dependent Schroedinger equation is solved for pendular analogs of coherent and squeezed states of a harmonic oscillator, induced by instantaneous changes of the periodic potential energy function. Coherent pendular states are discussed between the harmonic limit for small displacements and the inverted pendulum limit, while squeezed pendular states are shown to interpolate between vibrational and free rotational motion. In the latter case, full and fractional revivals as well as spatiotemporal structures in the time evolution ofmore » the probability densities (quantum carpets) are quantitatively analyzed. Corresponding expressions for the mean orientation are derived in terms of Mathieu functions in time. For periodic double well potentials, different revival schemes, and different quantum carpets are found for the even and odd initial states forming the ground tunneling doublet. Time evolution of the mean alignment allows the separation of states with different parity. Implications for external (rotational) and internal (torsional) motion of molecules induced by intense laser fields are discussed.« less

A sensitivity analysis of a surface energy balance model to LAI (Leaf Area Index)

NASA Astrophysics Data System (ADS)

Maltese, A.; Cannarozzo, M.; Capodici, F.; La Loggia, G.; Santangelo, T.

2008-10-01

The LAI is a key parameter in hydrological processes, especially in the physically based distribution models. It is a critical ecosystem attribute since physiological processes such as photosynthesis, transpiration and evaporation depend on it. The diffusion of water vapor, momentum, heat and light through the canopy is regulated by the distribution and density of the leaves, branches, twigs and stems. The LAI influences the sensible heat flux H in the surface energy balance single source models through the calculation of the roughness length and of the displacement height. The aerodynamic resistance between the soil and within-canopy source height is a function of the LAI through the roughness length. This research carried out a sensitivity analysis of some of the most important parameters of surface energy balance models to the LAI time variation, in order to take into account the effects of the LAI variation with the phenological period. Finally empirical retrieved relationships between field spectroradiometric data and the field LAI measured via a light-sensitive instrument are presented for a cereal field.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gibson, Adam Paul

The authors present a measurement of the mass of the top quark. The event sample is selected from proton-antiproton collisions, at 1.96 TeV center-of-mass energy, observed with the CDF detector at Fermilab's Tevatron. They consider a 318 pb -1 dataset collected between March 2002 and August 2004. They select events that contain one energetic lepton, large missing transverse energy, exactly four energetic jets, and at least one displaced vertex b tag. The analysis uses leading-order tmore » $$\\bar{t}$$ and background matrix elements along with parameterized parton showering to construct event-by-event likelihoods as a function of top quark mass. From the 63 events observed with the 318 pb -1 dataset they extract a top quark mass of 172.0 ± 2.6(stat) ± 3.3(syst) GeV/c 2 from the joint likelihood. The mean expected statistical uncertainty is 3.2 GeV/c 2 for m $$\\bar{t}$$ = 178 GTeV/c 2 and 3.1 GeV/c 2 for m $$\\bar{t}$$ = 172.5 GeV/c 2. The systematic error is dominated by the uncertainty of the jet energy scale.« less

Enantiospecific adsorption of propranolol enantiomers on naturally chiral copper surface: A molecular dynamics simulation investigation

NASA Astrophysics Data System (ADS)

Sedghamiz, Tahereh; Bahrami, Maryam; Ghatee, Mohammad Hadi

2017-04-01

Adsorption of propranolol enantiomers on naturally chiral copper (Cu(3,1,17)S) and achiral copper (Cu(100)) surfaces were studied by molecular dynamics simulation to unravel the features of adsorbate-adsorbent enantioselectivity. Adsorption of S- and R-propranolol on Cu(3,1,17)S terraces (with 100 plane) leads mainly to endo- and exo-conformers, respectively. Simulated pair correlation function (g(r)) and mean square displacement (MSD) were analyzed to identify adsorption sites of enantiomers on Cu(3,1,17)S substrate surface, and their simulated binding energies were used to access the adsorption strength. According to (g(r)), R-propranolol adsorbs via naphtyl group while S-propranolol mainly adsorbs through chain group. R-enantiomer binds more tightly to the chiral substrate surface than S-enantiomer as indicated by a higher simulated binding energy by 2.74 kJ mol-1 per molecule. The difference in binding energies of propranolol enantiomers on naturally chiral Cu(3,1,17)S is almost six times larger than on the achiral Cu(100) surface, which substantiates the appreciably strong specific enantioselective adsorption on the former surface.

Electronic conductance of a poly(p-phenylene)-like nanowire in the presence of thermal atomic vibrations

NASA Astrophysics Data System (ADS)

Shariati, Ashrafalsadat; Rabani, Hassan; Mardaani, Mohammad

2017-10-01

We present a theoretical method based on Green’s function technique and tight-binding approach as well as harmonic approximation in order to calculate the coherent electronic conductance of an extended poly(p-phenylene) oligomer in the presence of thermal atomic vibrations. We study two proposed mass-spring models for atomic vibrations: one, including rigid benzene rings connected to each other by vibrating bonds; and in another, the bonds along the oligomer vibrate even in the benzene rings. The electron-phonon (e-ph) interaction influences the electron hopping energies linearly with respect to atomic displacements. The model shows that the conductance spectra exhibit some new energy gaps in the presence of e-ph interaction even at zero temperature. The conductance is more affected by e-ph interaction when the atomic vibrations are supposed to be present in the benzene rings. At the edges of the band energy and central gap, the phonon-assisted phenomena can be observed. Generally, the increasing e-ph interaction strength as well as temperature destroys the electronic conductance especially in the resonance region.

Testing and performance of a new friction damper for seismic vibration control

NASA Astrophysics Data System (ADS)

Martínez, Carlos A.; Curadelli, Oscar

2017-07-01

In the last two decades, great efforts were carried out to reduce the seismic demand on structures through the concept of energy dissipation instead of increasing the stiffness and strength. Several devices based on different energy dissipation principles have been developed and implemented worldwide, however, most of the dissipation devices are usually installed using diagonal braces, which entail certain drawbacks on apertures for circulation, lighting or ventilation and architectural or functional requirements often preclude this type of installations. In this work, a conceptual development of a novel energy dissipation device, called Multiple Friction Damper (MFD), is proposed and examined. To verify its characteristics and performance, the MFD was implemented on a single storey steel frame experimental model and tested under different conditions of normal force and real time acceleration records. Experimental results demonstrated that the new MFD constitutes an effective and reliable alternative to control the structural response in terms of displacement and acceleration. A mathematical formulation based on the Wen's model reflecting the nonlinear behaviour of the device is also presented.

Acetabular fractures in the elderly treated with a primary Burch-Schneider reinforcement ring, autologous bone graft, and a total hip arthroplasty: a prospective study with a 4-year follow-up.

PubMed

Enocson, Anders; Blomfeldt, Richard

2014-06-01

To investigate the clinical and radiologic outcomes in elderly patients suffering from an acetabular fracture operated with an acute primary acetabular reinforcement ring, autologous bone graft, and a total hip arthroplasty (THA). Prospective cohort study. Tertiary care university hospital. Fifteen elderly patients (7 women) with a mean age of 76 years and a displaced acetabular fracture after a low-energy trauma were included. The fractures involved the anterior column, but no patients with associated both column fractures were included. All the patients were able to walk independently before the fracture occurred. Primary operation with a Burch-Schneider reinforcement ring, autologous bone graft, and a THA. The patients were reviewed at 4, 12, 24, and 48 months after the fracture occurred. The outcome assessments included complications, reoperations, activity of daily living function, functional scores (Harris hip score and short musculoskeletal function assessment), health-related quality of life [EuroQol (EQ-5D) index score], and radiologic evaluation. There were no prosthetic dislocations, periprosthetic fractures, deep infections, or other adverse events. There were no radiologic signs of loosening of the reinforcement ring or the prosthesis components at any of the follow up sessions, and the autologous bone graft was well incorporated in all the patients at the final follow-up. At 48 months, the mean Harris hip score was 88, the mean short musculoskeletal function assessment dysfunction score was 30, the bother score was 25, and the mean EQ-5D index score was 0.65. All the patients were able to walk independently at the final follow-up. Treatment of displaced anterior column, anterior column posterior hemitransverse and transverse acetabular fractures in elderly patients using a primary reinforcement ring, autologous bone graft, and a THA seems to be a safe option with good functional and radiologic outcomes. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Bearing system

DOEpatents

Kapich, Davorin D.

1987-01-01

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.