The parameters impact on cutting forces and determination of regression function
NASA Astrophysics Data System (ADS)
Popovici, T. D.
2016-11-01
The aim of this paper is to present results of certain experiments related to material workability characteristics, taking into consideration its high quality features and large usability for special manufacturing. It is highly used in various industrial processes, such as aeronautics, petrochemical industry, chemical industry, etc. It was examined the influence of milling parameters upon the three dimensional cutting force and after it was determinate regression function.
NASA Technical Reports Server (NTRS)
Vigue, Y.; Lichten, S. M.; Muellerschoen, R. J.; Blewitt, G.; Heflin, M. B.
1993-01-01
Data collected from a worldwide 1992 experiment were processed at JPL to determine precise orbits for the satellites of the Global Positioning System (GPS). A filtering technique was tested to improve modeling of solar-radiation pressure force parameters for GPS satellites. The new approach improves orbit quality for eclipsing satellites by a factor of two, with typical results in the 25- to 50-cm range. The resultant GPS-based estimates for geocentric coordinates of the tracking sites, which include the three DSN sites, are accurate to 2 to 8 cm, roughly equivalent to 3 to 10 nrad of angular measure.
Determining force field parameters using a physically based equation of state.
van Westen, Thijs; Vlugt, Thijs J H; Gross, Joachim
2011-06-23
Force field parameters used in classical molecular simulations can be estimated from quantum mechanical calculations or spectroscopic measurements. This especially applies to bonded interactions such as bond-stretching, bond-bending, and torsional interactions. However, it is difficult and computational expensive to obtain accurate parameters describing the nonbonded van der Waals interactions from quantum mechanics. In many studies, these parameters are adjusted to reproduce experimental data, such as vapor-liquid equilibria (VLE) data. Adjusting these force field parameters to VLE data is currently a cumbersome and computationally expensive task. The reason is that the result of a calculation of the vapor-liquid equilibria depends on the van der Waals interactions of all atom types in the system, therefore requiring many time-consuming iterations. In this work, we use an analytical equation of state, the perturbed chain statistical associating fluid theory (PC-SAFT), to predict the results of molecular simulations for VLE. The analytical PC-SAFT equation of state is used to approximate the objective function f(p) as a function of the array of force field parameters p. The objective function is here for example defined as the deviations of vapor pressure, enthalpy of vaporization and liquid density data, with respect to experimental data. The parameters are optimized using the analytical PC-SAFT equation of state, which is orders of magnitude quicker to calculate than molecular simulation. The solution is an excellent approximation of the real objective function, so that the resulting method requires only very few molecular simulation runs to converge. The method is here illustrated by optimizing transferable Lennard-Jones parameters for the n-alkane series. Optimizing four force field parameters p = (ε(CH(2))(CH(2)), ε(CH(3))(CH(3)), σ(CH(2))(CH(2)), σ(CH(3))(CH(3))) we obtain excellent agreement of coexisting densities, vapor pressure and caloric properties
NASA Technical Reports Server (NTRS)
Luthcke, S. B.; Marshall, J. A.
1992-01-01
The TOPEX/Poseidon spacecraft was launched on August 10, 1992 to study the Earth's oceans. To achieve maximum benefit from the altimetric data it is to collect, mission requirements dictate that TOPEX/Poseidon's orbit must be computed at an unprecedented level of accuracy. To reach our pre-launch radial orbit accuracy goals, the mismodeling of the radiative nonconservative forces of solar radiation, Earth albedo an infrared re-radiation, and spacecraft thermal imbalances cannot produce in combination more than a 6 cm rms error over a 10 day period. Similarly, the 10-day drag modeling error cannot exceed 3 cm rms. In order to satisfy these requirements, a 'box-wing' representation of the satellite has been developed in which, the satellite is modelled as the combination of flat plates arranged in the shape of a box and a connected solar array. The radiative/thermal nonconservative forces acting on each of the eight surfaces are computed independently, yielding vector accelerations which are summed to compute the total aggregate effect on the satellite center-of-mass. Select parameters associated with the flat plates are adjusted to obtain a better representation of the satellite acceleration history. This study analyzes the estimation of these parameters from simulated TOPEX/Poseidon laser data in the presence of both nonconservative and gravity model errors. A 'best choice' of estimated parameters is derived and the ability to meet mission requirements with the 'box-wing' model evaluated.
NASA Astrophysics Data System (ADS)
Luthcke, S. B.; Marshall, J. A.
1992-11-01
The TOPEX/Poseidon spacecraft was launched on August 10, 1992 to study the Earth's oceans. To achieve maximum benefit from the altimetric data it is to collect, mission requirements dictate that TOPEX/Poseidon's orbit must be computed at an unprecedented level of accuracy. To reach our pre-launch radial orbit accuracy goals, the mismodeling of the radiative nonconservative forces of solar radiation, Earth albedo an infrared re-radiation, and spacecraft thermal imbalances cannot produce in combination more than a 6 cm rms error over a 10 day period. Similarly, the 10-day drag modeling error cannot exceed 3 cm rms. In order to satisfy these requirements, a 'box-wing' representation of the satellite has been developed in which, the satellite is modelled as the combination of flat plates arranged in the shape of a box and a connected solar array. The radiative/thermal nonconservative forces acting on each of the eight surfaces are computed independently, yielding vector accelerations which are summed to compute the total aggregate effect on the satellite center-of-mass. Select parameters associated with the flat plates are adjusted to obtain a better representation of the satellite acceleration history. This study analyzes the estimation of these parameters from simulated TOPEX/Poseidon laser data in the presence of both nonconservative and gravity model errors. A 'best choice' of estimated parameters is derived and the ability to meet mission requirements with the 'box-wing' model evaluated.
Yanai, Toshimasa; Matsuo, Akifumi; Maeda, Akira; Nakamoto, Hiroki; Mizutani, Mirai; Kanehisa, Hiroaki; Fukunaga, Tetsuo
2017-01-13
We developed a force measurement system in a soil-filled mound for measuring ground reaction forces (GRFs) acting on baseball pitchers and examined the reliability and validity of kinetic and kinematic parameters determined from the GRFs. Three soil-filled trays of dimensions that satisfied the official baseball rules were fixed onto three force platforms. Eight collegiate pitchers wearing baseball shoes with metal cleats were asked to throw 5 fastballs with maximum effort from the mound toward a catcher. The reliability of each parameter was determined for each subject as the coefficient of variation across the 5 pitches. The validity of the measurements was tested by comparing the outcomes either with the true values or the corresponding values computed from a motion capture system. The coefficients of variation in the repeated measurements of the peak forces ranged from 0.00 to 0.17, and were smaller for the pivot foot than the stride foot. The mean absolute errors in the impulses determined over entire duration of pitching motion were 5.3 N·s, 1.9 N·s, and 8.2 N·s for the X-, Y-, and Z-directions, respectively. These results suggest that the present method is reliable and valid for determining selected kinetic and kinematic parameters for analyzing pitching performance.
2015-05-27
ParFit is a flexible and extendable framework and library of classes for fitting force-field parameters to data from high-level ab-initio calculations on the basis of deterministic and stochastic algorithms. Currently, the code is fitting MM3 and Merck force-field parameters but could easily extend to other force-field types.
NASA Astrophysics Data System (ADS)
Medan, N.; Banica, M.
2016-11-01
The regular cleaning of the materials deposed in sewer networks is realized, especially with equipment that uses high pressure water jets. The functioning of this equipment is dependent on certain process parameters that can vary, causing variations of the impact forces. The impact force directly affects the cleaning of sewer systems. In order to determine the influence of the process parameters on the impact forces produced by water jets the method of research used is the experiment. The research methods used is that Taguchi design and full factorial design. For the experimental determination of the impact forces a stand for generating water jets and a device for measuring the forces of impact are used. The processing of data is carried out using the Software Minitab 17.
Simple Criteria to Determine the Set of Key Parameters of the DRPE Method by a Brute-force Attack
NASA Astrophysics Data System (ADS)
Nalegaev, S. S.; Petrov, N. V.
Known techniques of breaking Double Random Phase Encoding (DRPE), which bypass the resource-intensive brute-force method, require at least two conditions: the attacker knows the encryption algorithm; there is an access to the pairs of source and encoded images. Our numerical results show that for the accurate recovery by numerical brute-force attack, someone needs only some a priori information about the source images, which can be quite general. From the results of our numerical experiments with optical data encryption DRPE with digital holography, we have proposed four simple criteria for guaranteed and accurate data recovery. These criteria can be applied, if the grayscale, binary (including QR-codes) or color images are used as a source.
Hermosilla, Laura; Prampolini, Giacomo; Calle, Paloma; García de la Vega, José Manuel; Brancato, Giuseppe; Barone, Vincenzo
2015-01-01
A computational strategy that combines both time-dependent and time-independent approaches is exploited to accurately model molecular dynamics and solvent effects on the isotropic hyperfine coupling constants of the DMPO-H nitroxide. Our recent general force field for nitroxides derived from AMBER ff99SB is further extended to systems involving hydrogen atoms in β-positions with respect to NO. The resulting force-field has been employed in a series of classical molecular dynamics simulations, comparing the computed EPR parameters from selected molecular configurations to the corresponding experimental data in different solvents. The effect of vibrational averaging on the spectroscopic parameters is also taken into account, by second order vibrational perturbation theory involving semi-diagonal third energy derivatives together first and second property derivatives. PMID:26584116
Estimates of Running Ground Reaction Force Parameters from Motion Analysis.
Pavei, Gaspare; Seminati, Elena; Storniolo, Jorge L L; Peyré-Tartaruga, Leonardo A
2017-02-01
We compared running mechanics parameters determined from ground reaction force (GRF) measurements with estimated forces obtained from double differentiation of kinematic (K) data from motion analysis in a broad spectrum of running speeds (1.94-5.56 m⋅s(-1)). Data were collected through a force-instrumented treadmill and compared at different sampling frequencies (900 and 300 Hz for GRF, 300 and 100 Hz for K). Vertical force peak, shape, and impulse were similar between K methods and GRF. Contact time, flight time, and vertical stiffness (kvert) obtained from K showed the same trend as GRF with differences < 5%, whereas leg stiffness (kleg) was not correctly computed by kinematics. The results revealed that the main vertical GRF parameters can be computed by the double differentiation of the body center of mass properly calculated by motion analysis. The present model provides an alternative accessible method for determining temporal and kinetic parameters of running without an instrumented treadmill.
The role of impulse parameters in force variability
NASA Technical Reports Server (NTRS)
Carlton, L. G.; Newell, K. M.
1986-01-01
One of the principle limitations of the human motor system is the ability to produce consistent motor responses. When asked to repeatedly make the same movement, performance outcomes are characterized by a considerable amount of variability. This occurs whether variability is expressed in terms of kinetics or kinematics. Variability in performance is of considerable importance because for tasks requiring accuracy it is a critical variable in determining the skill of the performer. What has long been sought is a description of the parameter or parameters that determine the degree of variability. Two general experimental protocals were used. One protocal is to use dynamic actions and record variability in kinematic parameters such as spatial or temporal error. A second strategy was to use isometric actions and record kinetic variables such as peak force produced. What might be the important force related factors affecting variability is examined and an experimental approach to examine the influence of each of these variables is provided.
Force-field parameters for beryllium complexes in amorphous layers.
Emelyanova, Svetlana; Chashchikhin, Vladimir; Bagaturyants, Alexander
2016-09-01
Unknown force-field parameters for metal organic beryllium complexes used in emitting and electron transporting layers of OLED structures are determined. These parameters can be used for the predictive atomistic simulations of the structure and properties of amorphous organic layers containing beryllium complexes. The parameters are found for the AMBER force field using a relaxed scan procedure and quantum-mechanical DFT calculations of potential energy curves for specific internal (angular) coordinates in a series of three Be complexes (Bebq2; Be(4-mpp)2; Bepp2). The obtained parameters are verified in calculations of some molecular and crystal structures available from either quantum-mechanical DFT calculations or experimental data. Graphical Abstract Beryllium complexes in amorphous layersᅟ.
What Determines Knudsen Force at the Microscale
NASA Astrophysics Data System (ADS)
Nabeth, Jeremy S.; Chigullapalli, Sruti; Alexeenko, Alina A.
2011-05-01
Knudsen forces arise in microscale systems when there is a thermal gradient with a characteristic length scale comparable to the molecular mean free path of the ambient gas. These forces are sometimes referred as radiometric or thermo-molecular forces [1] and have been recently measured experimentally in a microscale configuration using heated atomic force microscopy (AFM) probes [2]. The Knudsen force on microstructures with thermal gradients can provide a novel actuation mechanism for mass detection, thermogravimetry, and very high-resolution heat flux measurements. While measuring such forces precisely at microscale can be an arduous task especially since only limited analytical results exist, numerical simulations can provide a basis for understanding the physical mechanisms governing the generation of Knudsen forces. The main goal of this paper is to determine the dependence of the Knudsen force on pressure, geometry and thermal gradients based on rarefied flow simulations and to investigate the effects of the Knudsen force on the dynamics of microbeams.
Frey Law, Laura A; Shields, Richard K
2005-01-01
Background Mathematical muscle models may be useful for the determination of appropriate musculoskeletal stresses that will safely maintain the integrity of muscle and bone following spinal cord injury. Several models have been proposed to represent paralyzed muscle, but there have not been any systematic comparisons of modelling approaches to better understand the relationships between model parameters and muscle contractile properties. This sensitivity analysis of simulated muscle forces using three currently available mathematical models provides insight into the differences in modelling strategies as well as any direct parameter associations with simulated muscle force properties. Methods Three mathematical muscle models were compared: a traditional linear model with 3 parameters and two contemporary nonlinear models each with 6 parameters. Simulated muscle forces were calculated for two stimulation patterns (constant frequency and initial doublet trains) at three frequencies (5, 10, and 20 Hz). A sensitivity analysis of each model was performed by altering a single parameter through a range of 8 values, while the remaining parameters were kept at baseline values. Specific simulated force characteristics were determined for each stimulation pattern and each parameter increment. Significant parameter influences for each simulated force property were determined using ANOVA and Tukey's follow-up tests (α ≤ 0.05), and compared to previously reported parameter definitions. Results Each of the 3 linear model's parameters most clearly influence either simulated force magnitude or speed properties, consistent with previous parameter definitions. The nonlinear models' parameters displayed greater redundancy between force magnitude and speed properties. Further, previous parameter definitions for one of the nonlinear models were consistently supported, while the other was only partially supported by this analysis. Conclusion These three mathematical models use
Force Field Parameter Estimation of Functional Perfluoropolyether Lubricants
Smith, R.; Chung, P.S.; Steckel, J; Jhon, M.S.; Biegler, L.T.
2011-01-01
The head disk interface in a hard disk drive can be considered to be one of the hierarchical multiscale systems, which require the hybridization of multiscale modeling methods with coarse-graining procedure. However, the fundamental force field parameters are required to enable the coarse-graining procedure from atomistic/molecular scale to mesoscale models. In this paper, we investigate beyond molecular level and perform ab initio calculations to obtain the force field parameters. Intramolecular force field parameters for Zdol and Ztetraol were evaluated with truncated PFPE molecules to allow for feasible quantum calculations while still maintaining the characteristic chemical structure of the end groups. Using the harmonic approximation to the bond and angle potentials, the parameters were derived from the Hessian matrix, and the dihedral force constants are fit to the torsional energy profiles generated by a series of constrained molecular geometry optimization.
Force Field Parameter Estimation of Functional Perfluoropolyether Lubricants
Smith, R; Chung, P S; Steckel, J A; Jhon, M S; Biegler, L T
2011-01-01
The head disk interface in hard disk drive can be considered one of the hierarchical multiscale systems, which require the hybridization of multiscale modeling methods with coarse-graining procedure. However, the fundamental force field parameters are required to enable the coarse-graining procedure from atomistic/molecular scale to mesoscale models .In this paper, we investigate beyond molecular level and perform ab-initio calculations to obtain the force field parameters. Intramolecular force field parameters for the Zdol and Ztetraolwere evaluated with truncated PFPE molecules to allow for feasible quantum calculations while still maintaining the characteristic chemical structure of the end groups. Using the harmonic approximation to the bond and angle potentials, the parameters were derived from the Hessian matrix, and the dihedral force constants are fit to the torsional energy profiles generated by a series of constrained molecular geometry optimization.
Cell Forces and Cytoskeletal Order Parameters
NASA Astrophysics Data System (ADS)
Discher, Dennis
2012-02-01
Nematic, Smectic and Isotropic Order parameters have found wide-spread use in characterizing all manner of soft matter systems, but have not yet been applied to characterize and understand the structures within living cells, particularly cytoskeletal structures. Several examples will be used to illustrate the utility of such analyses, ranging from experiments on stem cells attached to or in various elastic matrices to embryonic heart tissue and simulations of membrane cytoskeletons under all manner of stressing. Recently developed theory will be shown to apply in general with account of cell contractility, matrix elasticity and dimensionality as well as cell shape and a newly defined ``cytoskeletal polarizability.'' The latter property of cells is likely different between different cell types due to different amounts of key cytoskeletal components with some types of stem cells being more polarizable than others. Evidence of coupling to the nucleus as a viscoelastic inclusion will also be presented. [4pt] References: (1) P. Dalhaimer, D.E. Discher, T. Lubensky. Crosslinked actin networks exhibit liquid crystal elastomer behavior, including soft-mode elasticity. Nature Physics 3: 354-360 (2007). (2) A. Zemel, F.Rehfeldt, A.E.X. Brown, D.E. Discher, and S.A. Safran. Optimal matrix rigidity in the self-polarization of stem cells. Nature Physics 6: 468 - 473 (2010).
Assessment of laparoscopic skills based on force and motion parameters.
Horeman, Tim; Dankelman, Jenny; Jansen, Frank Willem; van den Dobbelsteen, John J
2014-03-01
Box trainers equipped with sensors may help in acquiring objective information about a trainee's performance while performing training tasks with real instruments. The main aim of this study is to investigate the added value of force parameters with respect to commonly used motion and time parameters such as path length, motion volume, and task time. Two new dynamic bimanual positioning tasks were developed that not only requiring adequate motion control but also appropriate force control successful completion. Force and motion data for these tasks were studied for three groups of participants with different experience levels in laparoscopy (i.e., 11 novices, 19 intermediates, and 12 experts). In total, 10 of the 13 parameters showed a significant difference between groups. When the data from the significant motion, time, and force parameters are used for classification, it is possible to identify the skills level of the participants with 100% accuracy. Furthermore, the force parameters of many individuals in the intermediate group exceeded the maximum values in the novice and expert group. The relatively high forces used by the intermediates argue for the inclusion of training and assessment of force application during tissue handling in future laparoscopic skills training programs.
Integral data analysis for resonance parameters determination
Larson, N.M.; Leal, L.C.; Derrien, H.
1997-09-01
Neutron time-of-flight experiments have long been used to determine resonance parameters. Those resonance parameters have then been used in calculations of integral quantities such as Maxwellian averages or resonance integrals, and results of those calculations in turn have been used as a criterion for acceptability of the resonance analysis. However, the calculations were inadequate because covariances on the parameter values were not included in the calculations. In this report an effort to correct for that deficiency is documented: (1) the R-matrix analysis code SAMMY has been modified to include integral quantities of importance, (2) directly within the resonance parameter analysis, and (3) to determine the best fit to both differential (microscopic) and integral (macroscopic) data simultaneously. This modification was implemented because it is expected to have an impact on the intermediate-energy range that is important for criticality safety applications.
Radiation force modeling for ICESat precision orbit determination
NASA Astrophysics Data System (ADS)
Webb, Charles Edward
2007-12-01
Precision orbit determination (POD) for the Ice, Cloud and land Elevation Satellite (ICESat) relies on an epoch-state batch filter, in which the dynamic models play a central role. Its implementation in the Multi-Satellite Orbit Determination Program (MSODP) originally included a box-and-wing model, representing the TOPEX/Poseidon satellite, to compute solar radiation forces. This "macro-model" has been adapted to the ICESat geometry, and additionally, extended to the calculation of forces induced by radiation reflected and emitted from the Earth. To determine the area and reflectivity parameters of the ICESat macro-model surfaces, a high-fidelity simulation of the radiation forces in low-Earth orbit was first developed, using a detailed model of the satellite, called the "micro-model". In this effort, new algorithms to compute such forces were adapted from a Monte Carlo Ray Tracing (MCRT) method originally designed to determine incident heating rates. After working with the vendor of the Thermal Synthesizer System (TSS) to implement these algorithms, a modified version of this software was employed to generate solar and Earth radiation forces for all ICESat orbit and attitude geometries. Estimates of the macro-model parameters were then obtained from a least-squares fit to these micro-model forces, applying an algorithm that also incorporated linear equality and inequality constraints to ensure feasible solutions. Three of these fitted solutions were selected for post-launch evaluation. Two represented conditions at the start and at the end of the mission, while the third comprised four separate solutions, one for each of the nominal satellite attitudes. In addition, three other sets of macro-model parameters were derived from area-weighted averaging of the micro-model reflectivities. They included solar-only and infrared-only spectral parameters, as well as a set combining these parameters. Daily POD solutions were generated with each of these macro-model sets
Determining Spacecraft Reaction Wheel Friction Parameters
NASA Technical Reports Server (NTRS)
Sarani, Siamak
2009-01-01
Software was developed to characterize the drag in each of the Cassini spacecraft's Reaction Wheel Assemblies (RWAs) to determine the RWA friction parameters. This tool measures the drag torque of RWAs for not only the high spin rates (greater than 250 RPM), but also the low spin rates (less than 250 RPM) where there is a lack of an elastohydrodynamic boundary layer in the bearings. RWA rate and drag torque profiles as functions of time are collected via telemetry once every 4 seconds and once every 8 seconds, respectively. Intermediate processing steps single-out the coast-down regions. A nonlinear model for the drag torque as a function of RWA spin rate is incorporated in order to characterize the low spin rate regime. The tool then uses a nonlinear parameter optimization algorithm based on the Nelder-Mead simplex method to determine the viscous coefficient, the Dahl friction, and the two parameters that account for the low spin-rate behavior.
Determining wave direction using curvature parameters.
de Queiroz, Eduardo Vitarelli; de Carvalho, João Luiz Baptista
2016-01-01
The curvature of the sea wave was tested as a parameter for estimating wave direction in the search for better results in estimates of wave direction in shallow waters, where waves of different sizes, frequencies and directions intersect and it is difficult to characterize. We used numerical simulations of the sea surface to determine wave direction calculated from the curvature of the waves. Using 1000 numerical simulations, the statistical variability of the wave direction was determined. The results showed good performance by the curvature parameter for estimating wave direction. Accuracy in the estimates was improved by including wave slope parameters in addition to curvature. The results indicate that the curvature is a promising technique to estimate wave directions.•In this study, the accuracy and precision of curvature parameters to measure wave direction are analyzed using a model simulation that generates 1000 wave records with directional resolution.•The model allows the simultaneous simulation of time-series wave properties such as sea surface elevation, slope and curvature and they were used to analyze the variability of estimated directions.•The simultaneous acquisition of slope and curvature parameters can contribute to estimates wave direction, thus increasing accuracy and precision of results.
Identification of vehicle parameters and estimation of vertical forces
NASA Astrophysics Data System (ADS)
Imine, H.; Fridman, L.; Madani, T.
2015-12-01
The aim of the present work is to estimate the vertical forces and to identify the unknown dynamic parameters of a vehicle using the sliding mode observers approach. The estimation of vertical forces needs a good knowledge of dynamic parameters such as damping coefficient, spring stiffness and unsprung masses, etc. In this paper, suspension stiffness and unsprung masses have been identified by the Least Square Method. Real-time tests have been carried out on an instrumented static vehicle, excited vertically by hydraulic jacks. The vehicle is equipped with different sensors in order to measure its dynamics. The measurements coming from these sensors have been considered as unknown inputs of the system. However, only the roll angle and the suspension deflection measurements have been used in order to perform the observer. Experimental results are presented and discussed to show the quality of the proposed approach.
Determination of kinetic parameters for biomass combustion.
Álvarez, A; Pizarro, C; García, R; Bueno, J L; Lavín, A G
2016-09-01
The aim of this work is to provide a wide database of kinetic data for the most common biomass by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). Due to the characteristic parameters of DTG curves, a two-stage reaction model is proposed and the kinetic parameters obtained from model-based methods with energy activation values for first and second stages in the range 1.75·10(4)-1.55·10(5)J/mol and 1.62·10(4)-2.37·10(5)J/mol, respectively. However, it has been found that Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose model-free methods are not suitable to determine the kinetic parameters of biomass combustion since the assumptions of these two methods were not accomplished in the full range of the combustion process.
Determination of inertial parameters using a dynamometer.
Son, Jongsang; Ryu, Jeseong; Kim, Jungyoon; Kim, Youngho
2014-01-01
In this study, a simple method based on the dynamic equation of motion was introduced to determine the moment of inertia using a commercial dynamometer, and an optimization technique was utilized to estimate inertial parameters with the determined moment of inertia. To evaluate the feasibility of the developed method, three different passive speeds (i.e. 240, 270 and 300°/s) were chosen to confirm whether the moment of inertia values are the same irrespective of angular speeds. Moreover, the estimated inertial parameters (i.e., the mass, center of mass and moment of inertia) of the elbow attachment and the disk-like 3 kg-weight were compared with solutions of uniform square cube and solid disk, respectively. As a result, the values of moments of inertia of the elbow attachment were 0.216 ± 0.017, 0.215 ± 0.016 and 0.216 ± 0.017 kg · m(2) at angular speeds of 240, 270 and 300°/s, respectively. The values of the moment of inertia of both the attachment and weight were 0.821 ± 0.054, 0.823 ± 0.058 and 0.824 ± 0.053 kg · m(2) at angular speeds of 240, 270 and 300°/s, respectively. There were no significant differences among the speeds. The estimated inertial parameters of the attachment or the weight were very similar to the theoretical values. Therefore, it is expected that the developed method has the potential to estimate inertial parameters of a human body segment and to improve the accuracy and reliability of the studies on human dynamics.
Direct computation of parameters for accurate polarizable force fields
Verstraelen, Toon Vandenbrande, Steven; Ayers, Paul W.
2014-11-21
We present an improved electronic linear response model to incorporate polarization and charge-transfer effects in polarizable force fields. This model is a generalization of the Atom-Condensed Kohn-Sham Density Functional Theory (DFT), approximated to second order (ACKS2): it can now be defined with any underlying variational theory (next to KS-DFT) and it can include atomic multipoles and off-center basis functions. Parameters in this model are computed efficiently as expectation values of an electronic wavefunction, obviating the need for their calibration, regularization, and manual tuning. In the limit of a complete density and potential basis set in the ACKS2 model, the linear response properties of the underlying theory for a given molecular geometry are reproduced exactly. A numerical validation with a test set of 110 molecules shows that very accurate models can already be obtained with fluctuating charges and dipoles. These features greatly facilitate the development of polarizable force fields.
TDR method for determine IC's parameters
NASA Astrophysics Data System (ADS)
Timoshenkov, V.; Rodionov, D.; Khlybov, A.
2016-12-01
Frequency domain simulation is a widely used approach for determine integrated circuits parameters. This approach can be found in most of software tools used in IC industry. Time domain simulation approach shows intensive usage last years due to some advantages. In particular it applicable for analysis of nonlinear and nonstationary systems where frequency domain is inapplicable. Resolution of time domain systems allow see heterogeneities on distance 1mm, determine it parameters and properties. Authors used approach based on detecting reflected signals from heterogeneities - time domain reflectometry (TDR). Field effect transistor technology scaling up to 30-60nm gate length and 10nm gate dielectric, heterojunction bi-polar transistors with 10-30nm base width allows fabricate digital IC's with 20GHz clock frequency and RF-IC's with tens GHz bandwidth. Such devices and operation speed suppose transit signal by use microwave lines. There are local heterogeneities can be found inside of the signal path due to connections between different parts of signal lines (stripe line-RF-connector pin, stripe line - IC package pin). These heterogeneities distort signals that cause bandwidth decrease for RF-devices. Time domain research methods of transmission and reflected signals give the opportunities to determine heterogeneities, it properties, parameters and built up equivalent circuits. Experimental results are provided and show possibility for inductance and capacitance measurement up to 25GHz. Measurements contains result of signal path research on IC and printed circuit board (PCB) used for 12GHz RF chips. Also dielectric constant versus frequency was measured up to 35GHz.
Determining the Tsallis parameter via maximum entropy
NASA Astrophysics Data System (ADS)
Conroy, J. M.; Miller, H. G.
2015-05-01
The nonextensive entropic measure proposed by Tsallis [C. Tsallis, J. Stat. Phys. 52, 479 (1988), 10.1007/BF01016429] introduces a parameter, q , which is not defined but rather must be determined. The value of q is typically determined from a piece of data and then fixed over the range of interest. On the other hand, from a phenomenological viewpoint, there are instances in which q cannot be treated as a constant. We present two distinct approaches for determining q depending on the form of the equations of constraint for the particular system. In the first case the equations of constraint for the operator O ̂ can be written as Tr (FqO ̂)=C , where C may be an explicit function of the distribution function F . We show that in this case one can solve an equivalent maxent problem which yields q as a function of the corresponding Lagrange multiplier. As an illustration the exact solution of the static generalized Fokker-Planck equation (GFPE) is obtained from maxent with the Tsallis enropy. As in the case where C is a constant, if q is treated as a variable within the maxent framework the entropic measure is maximized trivially for all values of q . Therefore q must be determined from existing data. In the second case an additional equation of constraint exists which cannot be brought into the above form. In this case the additional equation of constraint may be used to determine the fixed value of q .
Gravity and Tide Parameters Determined from Satellite and Spacecraft Orbits
NASA Astrophysics Data System (ADS)
Jacobson, Robert A.
2015-05-01
As part of our work on the development of the Jovian and Saturnian satellite ephemerides to support the Juno and Cassini missions, we determined a number of planetary system gravity parameters. This work did not take into account tidal forces. In fact, we saw no obvious observational evidence of tidal effects on the satellite or spacecraft orbits. However, Lainey et al. (2009 Nature 459, 957) and Lainey et. al (2012 Astrophys. J. 752, 14) have published investigations of tidal effects in the Jovian and Saturnian systems, respectively. Consequently, we have begun a re-examination of our ephemeris work that includes a model for tides raised on the planet by the satellites as well as tides raised on the satellites by the planet. In this paper we briefly review the observations used in our ephemeris production; they include astrometry from the late 1800s to 2014, mutual events, eclipses, occultatons, and data acquired by the Pioneer, Voyager, Ulysses, Cassini, Galileo, and New Horizons spacecraft. We summarize the gravity parameter values found from our original analyses. Next we discuss our tidal acceleration model and its impact on the gravity parameter determination. We conclude with preliminary results found when the reprocessing of the observations includes tidal forces acting on the satellites and spacecraft.
Quantitative surface parameter maps using Intermodulation Atomic Force Microscopy
NASA Astrophysics Data System (ADS)
Forchheimer, Daniel; Platz, Daniel; Tholén, Erik; Hutter, Carsten; Haviland, David
2011-03-01
It is well known that the phase image in amplitude modulation atomic force microscopy (AM-AFM) is sensitive to material properties of the surface. However that information is not enough to fully quantify the tip-surface interaction. We have developed Intermodulation AFM, based on a spectral analysis of the cantilever's nonlinear dynamics, which increases the amount of information obtained without increasing scan time. We show how it is possible to extract quantitative material properties of the surface from this additional information. The method works under the assumption of a tip-surface force model, such as the DMT model, fitting the model parameters to the measured spectral data. The parameters are obtained at each pixel of the AFM image and form surface property maps which can be displayed together with topography. We demonstrate this on different surfaces such as polymer blends, extracting stiffness and adhesive properties. D. Platz, E. A. Tholen, D. Pesen, and D. B. Haviland, Appl. Phys. Lett., 92, 153106 (2008)
Determining safe limits for significant task parameters during manual lifting.
Singh, Ravindra Pratrap; Batish, Ajay; Singh, Tejinder Pal
2014-04-01
This experimental study investigated the effect of lifting task parameters (i.e., lifting weight, frequency, coupling, asymmetric angle, and vertical, horizontal, and travel distances) for various dynamic human lifting activities on the ground reaction forces of workers. Ten male workers loaded containers from different levels asymmetrically during experimental trials. The experimental design evolved using Taguchi's Fractional Factorial Experiments. Three factors (lifting weight, frequency, and vertical distance) were observed to be significant. The results showed that vertical reaction forces increase when workers lift weight from floor to shoulder height frequently. It was also observed that instantaneous loading rate increases with more weight, vertical distance, and frequency; a significant extra loading rate is required to change the lower level of load, frequency, and vertical distance to higher levels. Safe limits for significant factors were determined to result in optimal performance of the manual lifting task.
Development of glycyl radical parameters for the OPLS-AA/L force field.
Komáromi, István; Owen, Michael C; Murphy, Richard F; Lovas, Sándor
2008-09-01
On the basis of quantum chemical calculations C(alpha)-glycyl radical parameters have been developed for the OPLS-AA/L force field. The molecular mechanics hypersurface was fitted to the calculated quantum chemical surface by minimizing their molecular mechanics parameter dependent sum-of-squares deviations. To do this, a computer program in which the molecular mechanics energy derivatives with respect to the parameters were calculated analytically was developed, implementing the general method of Lifson and Warshel (J Chem Phys 1968, 49, 5116) for force field parameter optimization. This program, in principle, can determine the optimal parameter set in one calculation if enough representative value points on the quantum chemical potential energy surface are available and there is no linear dependency between the parameters. Some of the parameters in quantum calculations, including several new torsion types around a bond as well as angle parameters at a new central atom type, are not completely separable. Consequently, some restrictions and/or presumptions were necessary during parameter optimization. The relative OPLS-AA energies reproduced those calculated quantum chemically almost perfectly.
Relativity Parameters Determined from Lunar Laser Ranging
NASA Technical Reports Server (NTRS)
Williams, J. G.; Newhall, X. X.; Dickey, J. O.
1996-01-01
Analysis of 24 years of lunar laser ranging data is used to test the principle of equivalence, geodetic precession, the PPN parameters beta and gamma, and G/G. Recent data can be fitted with a rms scatter of 3 cm. (a) Using the Nordtvedt effect to test the principle of equivalence, it is found that the Moon and Earth accelerate alike in the Sun's field. The relative accelerations match to within 5 x 10(exp -13) . This limit, combined with an independent determination of y from planetary time delay, gives beta. Including the uncertainty due to compositional differences, the parameter beta differs from unity by no more than 0.0014; and, if the weak equivalence principle is satisfied, the difference is no more than 0.0006. (b) Geodetic precession matches its expected 19.2 marc sec/yr rate within 0.7%. This corresponds to a 1% test of gamma. (c) Apart from the Nordtvedt effect, beta and gamma can be tested from their influence on the lunar orbit. It is argued theoretically that the linear combination 0.8(beta) + 1.4(gamma) can be tested at the 1% level of accuracy. For solutions using numerically derived partial derivatives, higher sensitivity is found. Both 6 and y match the values of general relativity to within 0.005, and the linear combination beta+ gamma matches to within 0,003, but caution is advised due to the lack of theoretical understanding of these sensitivities. (d) No evidence for a changing gravitational constant is found, with absolute value of G/G less than or equal to 8 x lO(exp -12)/yr. There is significant sensitivity to G/G through solar perturbations on the lunar orbit.
Mayaan, Evelyn; Moser, Adam; MacKerell, Alexander D.; York, Darrin M.
2010-01-01
Force field parameters specifically optimized for residues important in the study of RNA catalysis are derived from density-functional calculations in a fashion consistent with the CHARMM27 all-atom empirical force field. Parameters are presented for residues that model reactive RNA intermediates and transition state analogs, thio-substituted phosphates and phosphoranes, and bound Mg2+ and di-metal bridge complexes. Target data was generated via density-functional calculations at the B3LYP/6-311++G(3df,2p)//B3LYP/6-31++G(d,p) level. Partial atomic charges were initially derived from the CHelpG electrostatic potential fitting and subsequently adjusted to be consistent with the CHARMM27 charges and Lennard-Jones parameters were determined to reproduce interaction energies with water molecules. Bond, angle and torsion parameters were derived from the density-functional calculations and renormalized to maintain compatibility with the existing CHARMM27 parameters for standard residues. The extension of the CHARMM27 force field parameters for the non-standard biological residues presented here will have considerable use in simulations of ribozymes, including the study of freeze-trapped catalytic intermediates, metal ion binding and occupation, and thio effects. PMID:17186477
Measurement strategy and analytic model to determine firing pin force
NASA Astrophysics Data System (ADS)
Lesenciuc, Ioan; Suciu, Cornel
2016-12-01
As illustrated in literature, ballistics is a branch of theoretical mechanics, which studies the construction and working principles of firearms and ammunition, their effects, as well as the motions of projectiles and bullets1. Criminalistics identification, as part of judiciary identification represents an activity aimed at finding common traits of different objects, objectives, phenomena and beings, but more importantly, traits that differentiate each of them from similar ones2-4. In judicial ballistics, in the case of rifled firearms it is relatively simple for experts to identify the used weapon from traces left on the projectile, as the rifling of the barrel leaves imprints on the bullet, which remain approximately identical even after the respective weapon is fired 100 times with the same barrel. However, in the case of smoothbore firearms, their identification becomes much more complicated. As the firing cap suffers alterations from being hit by the firing pin, determination of the force generated during impact creates the premises for determining the type of firearm used to shoot the respective cartridge. The present paper proposes a simple impact model that can be used to evaluate the force generated by the firing pin during its impact with the firing cap. The present research clearly showed that each rifle, by the combination of the three investigated parameters (impact force maximum value, its variation diagram, and impact time) leave a unique trace. Application of such a method in ballistics can create the perspectives for formulating clear conclusions that eliminate possible judicial errors in this field.
Vanommeslaeghe, K; Raman, E Prabhu; MacKerell, A D
2012-12-21
Molecular mechanics force fields are widely used in computer-aided drug design for the study of drug candidates interacting with biological systems. In these simulations, the biological part is typically represented by a specialized biomolecular force field, while the drug is represented by a matching general (organic) force field. In order to apply these general force fields to an arbitrary drug-like molecule, functionality for assignment of atom types, parameters, and partial atomic charges is required. In the present article, algorithms for the assignment of parameters and charges for the CHARMM General Force Field (CGenFF) are presented. These algorithms rely on the existing parameters and charges that were determined as part of the parametrization of the force field. Bonded parameters are assigned based on the similarity between the atom types that define said parameters, while charges are determined using an extended bond-charge increment scheme. Charge increments were optimized to reproduce the charges on model compounds that were part of the parametrization of the force field. A "penalty score" is returned for every bonded parameter and charge, allowing the user to quickly and conveniently assess the quality of the force field representation of different parts of the compound of interest. Case studies are presented to clarify the functioning of the algorithms and the significance of their output data.
Vanommeslaeghe, K.; Raman, E. Prabhu; MacKerell, A. D.
2012-01-01
Molecular mechanics force fields are widely used in computer-aided drug design for the study of drug candidates interacting with biological systems. In these simulations, the biological part is typically represented by a specialized biomolecular force field, while the drug is represented by a matching general (organic) force field. In order to apply these general force fields to an arbitrary drug-like molecule, functionality for assignment of atom types, parameters and partial atomic charges is required. In the present article, algorithms for the assignment of parameters and charges for the CHARMM General Force Field (CGenFF) are presented. These algorithms rely on the existing parameters and charges that were determined as part of the parametrization of the force field. Bonded parameters are assigned based on the similarity between the atom types that define said parameters, while charges are determined using an extended bond-charge increment scheme. Charge increments were optimized to reproduce the charges on model compounds that were part of the parametrization of the force field. A “penalty score” is returned for every bonded parameter and charge, allowing the user to quickly and conveniently assess the quality of the force field representation of different parts of the compound of interest. Case studies are presented to clarify the functioning of the algorithms and the significance of their output data. PMID:23145473
Han, Sanghwa
2008-12-12
Estimation of structural perturbation induced by S-nitrosation is important to understand the mode of cellular signal transduction mediated by nitric oxide. Crystal structures of S-nitrosated proteins have been solved only for a few cases, however, so that molecular dynamics simulation may provide an alternative tool for probing structural perturbation. In this study AMBER-99 force field parameters for S-nitrosocysteine were developed and applied to molecular dynamics simulations of S-nitrosated thioredoxin. Geometry optimization at the level of HF/6-31G * was followed by a restrained electrostatic potential charge-fitting to obtain the atomic charges of S-nitrosocysteine. Force constants for bonds and angles were obtained from generalized AMBER force field. Torsional force constants for CC-SN and CS-NO were determined by fitting the torsional profiles obtained from geometry optimization with those from molecular mechanical energy minimization. Finally molecular dynamics simulations were performed with theses parameters on oxidized and reduced thioredoxin with and without S-nitrosocysteine. In all cases the root-mean-square deviations of alpha-carbons yielded well-behaved trajectories. The CC-SH dihedral angle which fluctuated severely during the simulation became quiet upon S-nitrosation. In conclusion the force field parameters developed in this study for S-nitrosocysteine appear to be suitable for molecular dynamics simulations of S-nitrosated proteins.
Dynamic Parameters Variability: Time Interval Interference on Ground Reaction Force During Running.
Pennone, Juliana; Mezêncio, Bruno; Amadio, Alberto C; Serrão, Júlio C
2016-04-01
The aim of this study was to determine the effect of the time between measures on ground reaction force running variability; 15 healthy men (age = 23.8 ± 3.7 years; weight = 72.8 ± 7.7 kg; height 174.3 ± 8.4 cm) performed two trials of running 45 minutes at 9 km/hr at intervals of seven days. The ground reaction forces were recorded every 5 minutes. The coefficients of variation of indicative parameters of the ground reaction forces for each condition were compared. The coefficients of variations of the ground reaction forces curve analyzed between intervals and sessions were 21.9% and 21.48%, respectively. There was no significant difference for the ground reaction forces parameters Fy1, tFy1, TC1, Imp50, Fy2, and tFy2 between intervals and sessions. Although the ground reaction forces variables present a natural variability, this variability in intervals and in sessions remained consistent, ensuring a high reliability in repeated measures designs.
Material parameter determination from scattering measurements
NASA Technical Reports Server (NTRS)
Dominek, A.; Park, A.; Peters, L., Jr.
1988-01-01
The electrical, macroscopic performance of isotropic material can generally be described through their constitutive scalar parameters, permittivity and permeability which are symbolically represented by epsilon and mu, respectively. These parameters relate the electric and magnetic flux densities to the electric and magnetic fields through the following relationships: (1) D=epsilonE; and (2) B=muH. It is through these parameters that the interaction of electromagnetic waves with material can be quantized in terms of reflection and transmission coefficients, and propagation and attenuation factors.
NASA Astrophysics Data System (ADS)
Kar, Chinmaya; Mohanty, A. R.
2008-01-01
This paper deals with determining various time-varying parameters that are instrumental in introducing noise and vibration in a helical gear system. The most important parameter is the contact line variation, which subsequently induces friction force variation, frictional torque variation and variation in the forces at the bearings. The contact line variation will also give rise to gear mesh stiffness and damping variations. All these parameters are simulated for a defect-free and two defective cases of a helical gear system. The defective cases include one tooth missing and two teeth missing in the helical gear. The algorithm formulated in this paper is found to be simple and effective in determining the time-varying parameters.
The use of impact force as a scale parameter for the impact response of composite laminates
NASA Technical Reports Server (NTRS)
Jackson, Wade C.; Poe, C. C., Jr.
1992-01-01
The building block approach is currently used to design composite structures. With this approach, the data from coupon tests is scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low velocity impacts where the mass of the impacter is large and the size of the specimen is small. For large mass impacts of moderately thick (0.35 to 0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large mass test results can be applied directly to other plates of the same size.
The use of impact force as a scale parameter for the impact response of composite laminates
NASA Technical Reports Server (NTRS)
Jackson, Wade C.; Poe, C. C., Jr.
1992-01-01
The building block approach is currently used to design composite structures. With this approach, the data from coupon tests are scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low-velocity impacts where the mass of the impacter is large, and the size of the specimen is small. For large-mass impacts of moderately thick (0.35-0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large-mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large-mass test results can be applied directly to other plates of the same thickness.
Experimental determination of terahertz atmospheric absorption parameters
NASA Astrophysics Data System (ADS)
Slocum, David M.; Goyette, Thomas M.; Giles, Robert H.; Nixon, William E.
2015-05-01
The terahertz frequency regime is often used as the `chemical fingerprint' region of the electromagnetic spectrum since many molecules exhibit a dense selection of rotational and vibrational transitions. Water is a major component of the atmosphere and since it has a large dipole moment the propagation of terahertz radiation will be dominated by atmospheric effects. This study will present the results of high--resolution broadband measurements of the terahertz atmospheric absorption and detail the technique for directly measuring the pressure broadening coefficients, absolute absorption coefficients, line positions, and continuum effects. Differences between these measured parameters and those tabulated in HITRAN will be discussed. Once the water vapor absorption was characterized, the same technique was used to measure the line parameters for methanol, a trace gas of interest within Earth's atmosphere. Methanol has a dense absorption spectrum in the terahertz frequency region and is an important molecule in fields such as environmental monitoring, security, and astrophysics. The data obtained in the present study will be of immediate use for the remote sensing community, as it is uncommon to measure this many independent parameters as well as to measure the absolute absorption of the transitions. Current models rely on tabulated databases of calculated values for the line parameters measured in this study. Differences between the measured data and those in the databases will be highlighted and discussed.
Human capacity for explosive force production: neural and contractile determinants.
Folland, J P; Buckthorpe, M W; Hannah, R
2014-12-01
This study assessed the integrative neural and contractile determinants of human knee extension explosive force production. Forty untrained participants performed voluntary and involuntary (supramaximally evoked twitches and octets - eight pulses at 300 Hz that elicit the maximum possible rate of force development) explosive isometric contractions of the knee extensors. Explosive force (F0-150 ms) and sequential rate of force development (RFD, 50-ms epochs) were measured. Surface electromyography (EMG) amplitude was recorded (superficial quadriceps and hamstrings, 50-ms epochs) and normalized (quadriceps to Mmax, hamstrings to EMGmax). Maximum voluntary force (MVF) was also assessed. Multiple linear regressions assessed the significant neural and contractile determinants of absolute and relative (%MVF) explosive force and sequential RFD. Explosive force production exhibited substantial interindividual variability, particularly during the early phase of contraction [F50, 13-fold (absolute); 7.5-fold (relative)]. Multiple regression explained 59-93% (absolute) and 35-60% (relative) of the variance in explosive force production. The primary determinants of explosive force changed during the contraction (F0-50, quadriceps EMG and Twitch F; RFD50-100, Octet RFD0-50; F100-150, MVF). In conclusion, explosive force production was largely explained by predictor neural and contractile variables, but the specific determinants changed during the phase of contraction.
Determination and analysis of synchronous motor's parameters
NASA Astrophysics Data System (ADS)
Mesņajevs, Aleksandrs; Zviedris, Andrejs
2009-01-01
In this work the parameters of synchronous machines are analyzed- direct-axis reaction Xad and quadrature-axis reaction Xaq. Methods of calculation in view of magnetic system's and its element's saturation are presented. It is shown that definition of these reactances, using as a basis a two-reaction method, is not correct and connected with work demanding chart analyzing calculations. The new approach to the qualitative and quantitative analysis of synchronous machine's operating modes which is based on consecutive use of the magnetic field's theory is offered, without it with two-reaction parameters Xad and Xaq. This approach is realized by means of a magnetic field's modeling using numerical methods with help of modern computers.
Determination of dose distributions and parameter sensitivity
Napier, B.A.; Farris, W.T.; Simpson, J.C.
1992-12-01
A series of scoping calculations has been undertaken to evaluate the absolute and relative contribution of different radionuclides and exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 005) examined the contributions of numerous parameters to the uncertainty distribution of doses calculated for environmental exposures and accumulation in foods. This study builds on the work initiated in the first scoping study of iodine in cow's milk and the third scoping study, which added additional pathways. Addressed in this calculation were the contributions to thyroid dose of infants from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows' milk from Feeding Regime 1 as described in Calculation 001.
Yu, Yue; Fursule, Ishan A; Mills, Landon C; Englert, Derek L; Berron, Brad J; Payne, Christina M
2017-03-01
2'-Hydroxybiphenyl-2-sulfinate (HBPS) desulfinase (DszB) catalyzes the cleavage of the carbon-sulfur bond from HBPS in the final step of microbial 4S pathway desulfurization reactions. DszB is notable for its substrate specificity and exhibits product inhibition, both of which hinder the overall 4S pathway turnover rate. To understand the molecular-level contributions to substrate and inhibitor binding to DszB, we plan to perform molecular dynamic simulations bound to an array of naphthenic molecules and biphenyl analogues of HBPS. However, many of the small molecules we are interested in are not included in standard force field packages, and thus, we must first produce accurate molecular mechanics force fields. Here, we develop and validate CHARMM-compatible force field parameters for the HBPS substrate, the 2-hydroxybiphenyl product, and potential inhibitors including: 2,2'-biphenol, 2-biphenyl carboxylic acid, 1,8-naphthosultam, and 1,8-naphthosultone. The selected molecules represent biphenyl compounds having both a single and double functional group and the planar naphthenic molecule class, all likely present in the oil-rich environment surrounding DszB-producing microorganisms. The Force Field Toolkit (ffTK) in VMD was used to optimize charge, bond distance, angle, and dihedral parameters. Optimized geometries were determined from quantum mechanical calculations. Molecular simulations of the molecules in explicit and implicit water solutions were conducted to assess the abilities of optimized parameters to recapitulate optimized geometries. Calculated infrared (IR) spectra were obtained and compared with experimental IR spectra for validation of the optimized MM parameters.
Simulation-based Extraction of Key Material Parameters from Atomic Force Microscopy
NASA Astrophysics Data System (ADS)
Alsafi, Huseen; Peninngton, Gray
Models for the atomic force microscopy (AFM) tip and sample interaction contain numerous material parameters that are often poorly known. This is especially true when dealing with novel material systems or when imaging samples that are exposed to complicated interactions with the local environment. In this work we use Monte Carlo methods to extract sample material parameters from the experimental AFM analysis of a test sample. The parameterized theoretical model that we use is based on the Virtual Environment for Dynamic AFM (VEDA) [1]. The extracted material parameters are then compared with the accepted values for our test sample. Using this procedure, we suggest a method that can be used to successfully determine unknown material properties in novel and complicated material systems. We acknowledge Fisher Endowment Grant support from the Jess and Mildred Fisher College of Science and Mathematics,Towson University.
Experimental Determination of the Multiplicity Deadtime Parameter
Menaa, N.; Croft, S.; Kane, S.C.; Philips, S.; Villani, M.; Evans, L.G.
2008-07-01
Definition, extraction, and application of dead-time parameters, in correlated neutron counting, are long standing, thorny issues. Traditionally, dead-time corrections have been estimated on the assumption of a simple paralyzing model, arising from the action of the discriminator in the charged amplifiers connected to the {sup 3}He proportional counters, using a fixed dead-time. Various schemes exist to apply the paralysable model to the multiplicity shift register histogram data. In principle, several methods could be used to estimate the dead-time parameter. The approach which is most widely applied involves measuring a series of Cf-252 sources spanning a wide dynamic range of counting rates. Ratios between the Singles, Doubles and Triples rates which ought to be independent of fissile mass are extracted. The dead-time is chosen so as to achieve the best independence in the ratios, characteristic of the fissioning system, over the counting range. These measurements can be quite laborious to conduct; require a set of Cf-252 sources matched in construction and isotopic composition; require long counts to achieve the requisite precision and involve a good deal of numerical analysis to interpret. In this work we present a simpler scheme which produces comparable values in a way that is easier to implement. In essence we place a near random neutron source, such as may be realized using Am/Li {alpha}-n sources, in the cavity and record the multiplicity histograms as one would for an assay. The variance to mean-squared is narrower than for a random counting experiment, however, as a result of the dead-time losses. A simple formula exists allowing the deadtime to be extracted from this measurement. In this paper, we present results for the traditional approach, the proposed approach and also a variation based on adjusting the total event rate by adding Am/Li sources to a single Cf-252 source fixed in position for the case of a pair of Passive Scrap Multiplicity Counters
New method for determination of critical parameters
NASA Astrophysics Data System (ADS)
Ruge, C.; Dunkelmann, S.; Wagner, F.
1992-10-01
Our method uses topological properties of the large clusters in the single-cluster algorithm of Wolff for Monte Carlo simulations of spin systems. We have applied this method to the d=3 Ising model with film geometry near the special transition. As a test for the method we determined the bulk critical temperature and the critical indices in fair agreement with the results obtained by other methods. The new results refer to the critical surface coupling J1c/J=1.5004(20) and the surface exponents, where φ=0.461(15) and βmi=0.237(5).
Miller, Ross H; Umberger, Brian R; Caldwell, Graham E
2012-05-11
An accumulation of evidence suggests that the force-velocity relationship (FVR) of skeletal muscle plays a major role in limiting maximum human sprinting speed. However, most of the theories on this limiting role have been non-specific as to how the FVR limits speed. The FVR is characterized by three parameters that each have a different effect on its shape, and could thus limit sprinting speed in different ways: the maximum shortening velocity V(max), the shape parameter A(R), and the eccentric plateau C(ecc). In this study, we sought to determine how specifically the FVR limits sprinting speed using forward dynamics simulations of human locomotion to examine the sensitivity of maximum speed to these three FVR parameters. Simulations were generated by optimizing the model's muscle excitations to maximize the average horizontal speed. The simulation's speed, temporal stride parameters, joint angles, GRF, and muscle activity in general compared well to data from human subjects sprinting at maximum effort. Simulations were then repeated with incremental and isolated adjustments in V(max), A(R), and C(ecc) across a physiological range. The range of speeds (5.22-6.91 m s⁻¹) was most sensitive when V(max) was varied, but the fastest speed of 7.17 m s⁻¹ was attained when A(R) was set to its maximum value, which corresponded to all muscles having entirely fast-twitch fibers. This result was explained by the muscle shortening velocities, which tended to be moderate and within the range where A(R) had its greatest effect on the shape of the FVR. Speed was less sensitive to adjustments in C(ecc), with a range of 6.23-6.70 m s⁻¹. Increases in speed with parameter changes were due to increases in stride length more so than stride frequency. The results suggest that the shape parameter A(R), which primarily determines the amount of muscle force that can be produced at moderate shortening velocities, plays a major role in limiting the maximum sprinting speed. Analysis
Aman, Zachary M; Joshi, Sanjeev E; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A
2012-06-15
Hydrate aggregation and deposition are critical factors in determining where and when hydrates may plug a deepwater flowline. We present the first direct measurement of structure II (cyclopentane) hydrate cohesive forces in the water, liquid hydrocarbon and gas bulk phases. For fully annealed hydrate particles, gas phase cohesive forces were approximately twice that obtained in a liquid hydrocarbon phase, and approximately six times that obtained in the water phase. Direct measurements show that hydrate cohesion force in a water-continuous bulk may be only the product of solid-solid cohesion. When excess water was present on the hydrate surface, gas phase cohesive forces increased by a factor of three, suggesting the importance of the liquid or quasi-liquid layer (QLL) in determining cohesive force. Hydrate-steel adhesion force measurements show that, when the steel surface is coated with hydrophobic wax, forces decrease up to 96%. As the micromechanical force technique is uniquely capable of measuring hydrate-surface forces with variable contact time, the present work contains significant implications for hydrate applications in flow assurance.
The Friction Force Determination of Large-Sized Composite Rods in Pultrusion
NASA Astrophysics Data System (ADS)
Grigoriev, S. N.; Krasnovskii, A. N.; Kazakov, I. A.
2014-08-01
Nowadays, the simple pull-force models of pultrusion process are not suitable for large sized rods because they are not considered a chemical shrinkage and thermal expansion acting in cured material inside the die. But the pulling force of the resin-impregnated fibers as they travels through the heated die is essential factor in the pultrusion process. In order to minimize the number of trial-and-error experiments a new mathematical approach to determine the frictional force is presented. The governing equations of the model are stated in general terms and various simplifications are implemented in order to obtain solutions without extensive numerical efforts. The influence of different pultrusion parameters on the frictional force value is investigated. The results obtained by the model can establish a foundation by which process control parameters are selected to achieve an appropriate pull-force and can be used for optimization pultrusion process.
2009-01-01
the Philippine Marine Corps in Internal Security Operations 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) 5d. PROJECT...It is worthy to note that the Marine Corps perceive" s ISO primarily as a mere force on force employment (combat operations) against armed internal ...Virginia 22134-5068 MASTERS OF MILITARY STUDIES ASSESSING THE PARAMETERS FOR DETERMINING MISSION ACCOMPLISHMENT 011 THE PHILIPPINE MARINE CORPS IN INTERNAL
NASA Technical Reports Server (NTRS)
DeWitt, John; Schaffner, Grant; Laughlin, Mitzi; Loehr, James; Hagan, R. Donald
2004-01-01
Long-term exposure to microgravity induces detrimefits to the musculcskdetal system (Schneider et al., 1995; LeBlanc et al., 2000). Treadmill exercise is used onboard the International Space Station as an exercise countermeasure to musculoskeletal deconditioning due to spaceflight. During locomotive exercise in weightlessness (0G), crewmembers wear a harness attached to an external loading mechanism (EL). The EL pulls the crewmember toward the treadmill, and provides resistive load during the impact and propulsive phases of gait. The resulting forces may be important in stimulating bone maintenance (Turner, 1998). The EL can be applied via a bungee and carabineer clip configuration attached to the harness and can be manipulated to create varying amounts of load levels during exercise. Ground-based research performed using a vertically mounted treadmill found that peak ground reaction forces (GRF) during running at an EL of less than one body weight (BW) are less than those that occur during running in normal gravity (1G) (Davis et al., 1996). However, it is not known how the GRF are affected by the EL in a true OG environment. Locomotion while suspended may result in biomechanics that differ from free running. The purpose of this investigation was to determine how EL affects peak impact force, peak propulsive force, loading rate, and impulse of the GRF during running in 0G. It was hypothesized that increasing EL would result in increases in each GRF parameter.
DETERMINATION OF TANGENTIAL AND NORMAL COMPONENTS OF ORAL FORCES
Casas, Estevam Barbosa de Las; de Almeida, André França; Cimini, Carlos Alberto; Gomes, Paulo de Tarso Vida; Cornacchia, Tulimar Pereira Machado; Saffar, Jorge Milton Elian
2007-01-01
Oral forces applied to human teeth during biting and mastication are normally described in the literature only in terms of their axial components. The purpose of this study was to fully determine the spatial characteristics of the oral resultant force – its normal and tangential components - for a given individual. A load cell was especially manufactured to measure oral force and was temporarily implanted as a prosthetic device in the dental arch of a volunteer, replacing his missing upper first molar. The mastication and occlusion tests were carried out in such a way the cell should withstand the loads applied to the molar, and its state of strain was recorded by strain gauges attached to it. Based on the results of these tests and using balance equations, normal and tangential components of the resultant oral force were determined. For direct occlusion, without interposition any obstacle between cusps, a peak normal force of 135 N was recorded simultaneously to a tangential force of 44 N. For mastication of biscuits, a peak normal force of 133 N and a tangential force of 39 N were obtained. PMID:19089104
Using explicit macroscopic feedback to determine efficacy of climate forcings
NASA Astrophysics Data System (ADS)
Kravitz, B.; MacMartin, D. G.
2013-12-01
Calculating efficacies of climate forcings has been a useful method of determining the importance of forcing agents relative to CO2. However, because the strength of internal feedbacks is dependent upon the climate state, efficacies are dependent upon the strengths of the applied forcings, and simulations designed to capture these efficacies have tradeoffs between simulation length and accurately capturing the steady state climate response. We propose an alternate method of determining a quantity similar to climate efficacy via adjusting the amount of forcing by feeding back the observed climate state. By balancing CO2 forcing with another climate forcing, many internal feedbacks are suppressed, which linearizes the climate response to the forcing and promotes rapid convergence of the simulation. We performed simulations in two fully coupled general circulation models of Earth's climate. Doubling the present day CO2 concentration requires a steady state solar reduction of approximately 2.5%; this answer can be obtained with a simulation of less than 30 years. With this method, the amount of solar reduction scales linearly with the logarithmic change in CO2 concentration. We explore similar calculations using other climate forcings. Because this method circumvents calculation of radiative forcing, intercomparison of values between different climate forcings is difficult and is a drawback of our method as compared to the original method of calculating efficacy. Feedback can be used to estimate the efficacy of solar reductions in models. The solar reduction that is required to maintain temperature in the presence of an instantaneous change in atmospheric CO2 concentrations is computed using feedback. The left-hand panel illustrates both the solar forcing as a function of time for offsetting 2×CO2, and the efficacy estimated as the mean solar reduction after the initial transient; extremely rapid convergence is obtained. The right-hand panel illustrates the linearity
Experimental and analytical determination of stability parameters for a balloon tethered in a wind
NASA Technical Reports Server (NTRS)
Redd, L. T.; Bennett, R. M.; Bland, S. R.
1973-01-01
Experimental and analytical techniques for determining stability parameters for a balloon tethered in a steady wind are described. These techniques are applied to a particular 7.64-meter-long balloon, and the results are presented. The stability parameters of interest appear as coefficients in linearized stability equations and are derived from the various forces and moments acting on the balloon. In several cases the results from the experimental and analytical techniques are compared and suggestions are given as to which techniques are the most practical means of determining values for the stability parameters.
Effect of hinge-moment parameters on elevator stick forces in rapid maneuvers
NASA Technical Reports Server (NTRS)
Jones, R. T.; Greenberg, H.
1976-01-01
The importance of the stick force per unit normal acceleration as a criterion of longitudinal stability and the critical dependence of this gradient on elevator hinge moment parameters are investigated with special reference to transient effects for maneuvers of short duration. The analysis shows that different combinations of elevator parameters, which give the same stick force per unit acceleration in turns, give widely different force variations during the entries into and recoveries from steady turns and during maneuvers of short duration such as abrupt pull-ups. The stick force per unit acceleration is greater for abrupt than for gradual control movements.
Physical parameter determination of seven RR Lyrae stars in Bootes
NASA Astrophysics Data System (ADS)
Peña, J. H.; Arellano, A.; Sareyan, J. P.; Peña, R.; Alvarez, M.
2007-06-01
uvbyβ photoelectric photometry of the RR Lyrae stars AE, RS, ST, TV, TW, UU, and XX Bootis has been acquired in order to determine the physical parameters of the stars. We used the correlation between the Fourier parameters derived from the light curves and the physical parameters such as the absolute magnitude M_v, intrinsic colour (B-V)_0 and metal abundance [Fe/H]. Once reddening has been determined, unreddened indices are obtained and T_{eff} and log g followed along the cycle, using a comparison with the theoretical models given for our determined metallicity.
Determination of critical nondimensional parameters in aircraft dynamic response to random input
NASA Technical Reports Server (NTRS)
Hillard, S. E.; Sevik, M. M.
1974-01-01
The critical parameters of subsonic jet aircraft response in a random atmospheric environment are determined. Equations of motion are presented for semirigid aircraft with a flexible primary airfoil. However, the analysis is easily extendable to include additional appendage flexibility. The analysis establishes the mechanical admittance values for pitching, plunging, and the first mode effects from wing elastic bending and torsion. Nondimensional parameters are established which allow the representation of all subsonic jet transport aircraft with one nondimensional model. The critical parameters for random forcing are found to be aircraft relative mass, reduced natural and forcing frequencies, and Mach number. Turbulence scale lengths are found to be directly related to the critical values of reduced forcing frequency. Results are given for subsonic craft traveling at constant altitude. Specific values of admittance functions are tabulated at Mach numbers of 0.2, 0.5, and 0.7. The relative mass range covers all aircraft currently in operation.
All-out Test in Tethered Canoe System can Determine Anaerobic Parameters of Elite Kayakers.
Messias, L H D; Ferrari, H G; Sousa, F A B; Dos Reis, I G M; Serra, C C S; Gobatto, C A; Manchado-Gobatto, F B
2015-10-01
The aims of this study were to use a specific all-out 30-sec tethered test to determine the anaerobic parameters in elite kayakers and verify the relationship between these results and sports performance. Twelve elite slalom kayakers were evaluated. The tethered canoe system was created and used for the all-out 30-sec test application. Measurements of peak force, mean force, minimum force, fatigue index and impulse were performed. Performance evaluation was determined by measuring the time of race in a simulated race containing 24 gates on a white-water course. Blood was collected (25-µl) for analysis of lactate concentration at rest and at 2, 4, 6, 8 and 10-min intervals after both the all-out test and the simulated race. The Pearson product moment correlation shows a inverse and significant relationship of peak force, mean force and impulse with time of race. Blood lactate concentrations after the all-out test and the simulated race peak at same time (4 min). Additionally, no interaction was visualized between time and all-out test/simulated race for blood lactate concentrations (P <0.365). These results suggest a relationship between the parameters of the all-out test and performance. Thus, the tethered canoe system is a useful tool for determining parameters that could be used in training control of slalom kayakers.
Factors influencing the determination of cell traction forces
Ehret, Alexander E.; Mazza, Edoardo
2017-01-01
Methods summarized by the term Traction Force Microscopy are widely used to quantify cellular forces in mechanobiological studies. These methods are inverse, in the sense that forces must be determined such that they comply with a measured displacement field. This study investigates how several experimental and analytical factors, originating in the realization of the experiments and the procedures for the analysis, affect the determined traction forces. The present results demonstrate that even for very high resolution measurements free of noise, traction forces can be significantly underestimated, while traction peaks are typically overestimated by 50% or more, even in the noise free case. Compared to this errors, which are inherent to the nature of the mechanical problem and its discretization, the effect of ignoring the out-of-plane displacement component, the interpolation scheme used between the discrete measurement points and the disregard of the geometrical non-linearities when using a nearly linear substrate material are less consequential. Nevertheless, a nonlinear elastic substrate, with strain-stiffening response and some degree of compressibility, can substantially improve the robustness of the reconstruction of traction forces over a wide range of magnitudes. This poses the need for a correct mechanical representation of these non-linearities during the traction reconstruction and a correct mechanical characterization of the substrate itself, especially for the large strain shear domain which is shown to plays a major role in the deformations induced by cells. PMID:28235004
Noninvasive determination of optical lever sensitivity in atomic force microscopy
Higgins, M.J.; Proksch, R.; Sader, J.E.; Polcik, M.; Mc Endoo, S.; Cleveland, J.P.; Jarvis, S.P.
2006-01-15
Atomic force microscopes typically require knowledge of the cantilever spring constant and optical lever sensitivity in order to accurately determine the force from the cantilever deflection. In this study, we investigate a technique to calibrate the optical lever sensitivity of rectangular cantilevers that does not require contact to be made with a surface. This noncontact approach utilizes the method of Sader et al. [Rev. Sci. Instrum. 70, 3967 (1999)] to calibrate the spring constant of the cantilever in combination with the equipartition theorem [J. L. Hutter and J. Bechhoefer, Rev. Sci. Instrum. 64, 1868 (1993)] to determine the optical lever sensitivity. A comparison is presented between sensitivity values obtained from conventional static mode force curves and those derived using this noncontact approach for a range of different cantilevers in air and liquid. These measurements indicate that the method offers a quick, alternative approach for the calibration of the optical lever sensitivity.
Determination of motility forces on isolated chromosomes with laser tweezers.
Khatibzadeh, Nima; Stilgoe, Alexander B; Bui, Ann A M; Rocha, Yesenia; Cruz, Gladys M; Loke, Vince; Shi, Linda Z; Nieminen, Timo A; Rubinsztein-Dunlop, Halina; Berns, Michael W
2014-10-31
Quantitative determination of the motility forces of chromosomes during cell division is fundamental to understanding a process that is universal among eukaryotic organisms. Using an optical tweezers system, isolated mammalian chromosomes were held in a 1064 nm laser trap. The minimum force required to move a single chromosome was determined to be ≈ 0.8-5 pN. The maximum transverse trapping efficiency of the isolated chromosomes was calculated as ≈ 0.01-0.02. These results confirm theoretical force calculations of ≈ 0.1-12 pN to move a chromosome on the mitotic or meiotic spindle. The verification of these results was carried out by calibration of the optical tweezers when trapping microspheres with a diameter of 4.5-15 µm in media with 1-7 cP viscosity. The results of the chromosome and microsphere trapping experiments agree with optical models developed to simulate trapping of cylindrical and spherical specimens.
Touhami, Ahmed; Jericho, Manfred H.; Boyd, Jessica M.; Beveridge, Terry J.
2006-01-01
Type IV pili play an important role in bacterial adhesion, motility, and biofilm formation. Here we present high-resolution atomic force microscopy (AFM) images of type IV pili from Pseudomonas aeruginosa bacteria. An individual pilus ranges in length from 0.5 to 7 μm and has a diameter from 4 to 6 nm, although often, pili bundles in which the individual filaments differed in both length and diameter were seen. By attaching bacteria to AFM tips, it was possible to fasten the bacteria to mica surfaces by pili tethers. Force spectra of tethered pili gave rupture forces of 95 pN. The slopes of force curves close to the rupture force were nearly linear but showed little variation with pilus length. Furthermore, force curves could not be fitted with wormlike-chain polymer stretch models when using realistic persistence lengths for pili. The observation that the slopes near rupture did not depend on the pili length suggests that they do not represent elastic properties of the pili. It is possible that this region of the force curves is determined by an elastic element that is part of the bacterial wall, although further experiments are needed to confirm this. PMID:16385026
Method and Apparatus for Determining Operational Parameters of Thermoelectric Modules
NASA Astrophysics Data System (ADS)
Zybała, Rafał; Schmidt, Maksymilian; Kaszyca, Kamil; Ciupiński, Łukasz; Kruszewski, Mirosław J.; Pietrzak, Katarzyna
2016-10-01
The main aim of this work was to construct and test an apparatus for characterization of high temperature thermoelectric modules to be used in thermoelectric generator (TEGs) applications. The idea of this apparatus is based on very precise measurements of heat fluxes passing through the thermoelectric (TE) module, at both its hot and cold sides. The electrical properties of the module, under different temperature and load conditions, were used to estimate efficiency of energy conversion based on electrical and thermal energy conservation analysis. The temperature of the cold side, T c, was stabilized by a precise circulating thermostat (≤0.1°C) in a temperature range from 5°C to 90°C. The amount of heat absorbed by a coolant flowing through the heat sink was measured by the calibrated and certified heat flow meter with an accuracy better than 1%. The temperature of the hot side, T h, was forced to assumed temperature ( T max = 450°C) by an electric heater with known power ( P h = 0-600 W) with ample thermal insulation. The electrical power was used in calculations. The TE module, heaters and cooling plate were placed in an adiabatic vacuum chamber. The load characteristics of the module were evaluated using an electronically controlled current source as a load. The apparatus may be used to determine the essential parameters of TE modules (open circuit voltage, U oc, short circuit current, I sc, internal electrical resistance, R int, thermal resistance, R th, power density, and efficiency, η, as a function of T c and T h ). Several commercially available TE modules based on Bi2Te3 and Sb2Te3 alloys were tested. The measurements confirmed that the constructed apparatus was highly accurate, stable and yielded reproducible results; therefore, it is a reliable tool for the development of thermoelectric generators.
Determination of dynamic surface forces using piezoelectric arrays
NASA Astrophysics Data System (ADS)
Nitsche, W.; Mirow, P.
The experimental determination of static and dynamic surface forces on flow bodies using piezoelectric arrays is outlined. The fundamentals of the piezo-array sensor technique (sensor construction, signal separation, and signal transmission) are presented. Practical applications of piezo-arrays in the fields of airfoil aerodynamics and general flow investigations are explained. The obtained measuring results are purely qualitative.
Method of determining fracture parameters for heterogenous formations
Solimon, M.Y.; Kuhlman, R.D.; Poulson, D.K.
1991-04-09
This patent describes a method of determining the parameters of a full scale fracturing treatment of a subterranean formation. It comprises injecting fluid into a wellbore penetrating the subterranean formation to generate a fracture in the formation; measuring the pressure of the fluid in the fracture over time; determining a leak-off exponent that characterizes the rate at which the fluid leaks off into the formation as a function of time; determining parameters of a fracturing treatment including fracture length and width using the leak-off exponent.
Yordanova, D; Smirnova, I; Jakobtorweihen, S
2015-05-12
Nonionic surfactants of the Triton X-series find various applications in extraction processes and as solubilizing agents for the purification of membrane proteins. However, so far no optimized parameters are available to perform molecular simulations with a biomolecular force field. Therefore, we have determined the first optimized set of CHARMM parameters for the Triton X-series, enabling all-atom molecular dynamics (MD) simulations. In order to validate the new parameters, micellar sizes (aggregation numbers) of Triton X-114 and Triton X-100 have been investigated as a function of temperature and surfactant concentration. These results are comparable with experimental results. Furthermore, we have introduced a new algorithm to obtain micelle structures from self-assembly MD simulations for the COSMOmic method. This model allows efficient partition behavior predictions once a representative micelle structure is available. The predicted partition coefficients for the systems Triton X-114/water and Triton X-100/water are in excellent agreement with experimental results. Therefore, this method can be applied as a screening tool to find optimal solute-surfactant combinations or suitable surfactant systems for a specific application.
The effect of machining parameters on force signal and tool wear in stone cutting
NASA Astrophysics Data System (ADS)
yousefi, Reza; Gorjizadeh, Ashkan; Mikaeil, Reza
2011-01-01
The application of sensor system is becoming more commonplace in improving productivity and reliability. Although measuring force signal have been widely used for monitoring of metal machining process that their application to stone cutting has not been well investigated. In this paper, the effect of machining parameter on force signal and tool wear was investigated. The result indicate that increasing of the depth of cut and spindle speed will increase the force and tool wear while increasing feed rate will increase force and decrease tool wear.
Determination of photosynthetic parameters in two seawater-tolerant vegetables
NASA Astrophysics Data System (ADS)
Qiu, Nianwei; Zhou, Feng; Liu, Qian; Zhao, Wenqian
2016-03-01
It is difficult to determine the photosynthetic parameters of non-flat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsa and Salicornia bigelovii as two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters (such as P N, g s, E) based on unit fresh mass, instead of leaf area. The light/CO2/temperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants.
Paramfit: automated optimization of force field parameters for molecular dynamics simulations.
Betz, Robin M; Walker, Ross C
2015-01-15
The generation of bond, angle, and torsion parameters for classical molecular dynamics force fields typically requires fitting parameters such that classical properties such as energies and gradients match precalculated quantum data for structures that scan the value of interest. We present a program, Paramfit, distributed as part of the AmberTools software package that automates and extends this fitting process, allowing for simplified parameter generation for applications ranging from single molecules to entire force fields. Paramfit implements a novel combination of a genetic and simplex algorithm to find the optimal set of parameters that replicate either quantum energy or force data. The program allows for the derivation of multiple parameters simultaneously using significantly fewer quantum calculations than previous methods, and can also fit parameters across multiple molecules with applications to force field development. Paramfit has been applied successfully to systems with a sparse number of structures, and has already proven crucial in the development of the Assisted Model Building with Energy Refinement Lipid14 force field.
Molecular determinants of bacterial adhesion monitored by atomic force microscopy
Razatos, Anneta; Ong, Yea-Ling; Sharma, Mukul M.; Georgiou, George
1998-01-01
Bacterial adhesion and the subsequent formation of biofilm are major concerns in biotechnology and medicine. The initial step in bacterial adhesion is the interaction of cells with a surface, a process governed by long-range forces, primarily van der Waals and electrostatic interactions. The precise manner in which the force of interaction is affected by cell surface components and by the physiochemical properties of materials is not well understood. Here, we show that atomic force microscopy can be used to analyze the initial events in bacterial adhesion with unprecedented resolution. Interactions between the cantilever tip and confluent monolayers of isogenic strains of Escherichia coli mutants exhibiting subtle differences in cell surface composition were measured. It was shown that the adhesion force is affected by the length of core lipopolysaccharide molecules on the E. coli cell surface and by the production of the capsular polysaccharide, colanic acid. Furthermore, by modifying the atomic force microscope tip we developed a method for determining whether bacteria are attracted or repelled by virtually any biomaterial of interest. This information will be critical for the design of materials that are resistant to bacterial adhesion. PMID:9736689
Determining Stand Parameters from Uas-Based Point Clouds
NASA Astrophysics Data System (ADS)
Yilmaz, V.; Serifoglu, C.; Gungor, O.
2016-06-01
In Turkey, forest management plans are produced by terrestrial surveying techniques for 10 or 20 year periods, which can be considered quite long to maintain the sustainability of forests. For a successful forest management plan, it is necessary to collect accurate information about the stand parameters and store them in dynamic and robust databases. The position, number, height and closure of trees are among the most important stand parameters required for a forest management plan. Determining the position of each single tree is challenging in such an area consisting of too many interlocking trees. Hence, in this study, an object-based tree detection methodology has been developed in MATLAB programming language to determine the position of each tree top in a highly closed area. The developed algorithm uses the Canopy Height Model (CHM), which is computed from the Digital Terrain Model (DTM) and Digital Surface Model (DSM) generated by using the point cloud extracted from the images taken from a UAS (Unmanned Aerial System). The heights of trees have been determined by using the CHM. The closure of the trees has been determined with the written MATLAB script. The results show that the developed tree detection methodology detected more than 70% of the trees successfully. It can also be concluded that the stand parameters may be determined by using the UAS-based point clouds depending on the characteristics of the study area. In addition, determination of the stand parameters by using point clouds reduces the time needed to produce forest management plans.
Yildirim, Ilyas; Stern, Harry A; Kennedy, Scott D; Tubbs, Jason D; Turner, Douglas H
2010-05-11
A reparameterization of the torsional parameters for the glycosidic dihedral angle, chi, for the AMBER99 force field in RNA nucleosides is used to provide a modified force field, AMBER99chi. Molecular dynamics simulations of cytidine, uridine, adenosine, and guanosine in aqueous solution using the AMBER99 and AMBER99chi force fields are compared with NMR results. For each nucleoside and force field, 10 individual molecular dynamics simulations of 30 ns each were run. For cytidine with AMBER99chi force field, each molecular dynamics simulation time was extended to 120 ns for convergence purposes. Nuclear magnetic resonance (NMR) spectroscopy, including one-dimensional (1D) (1)H, steady-state 1D (1)H nuclear Overhauser effect (NOE), and transient 1D (1)H NOE, was used to determine the sugar puckering and preferred base orientation with respect to the ribose of cytidine and uridine. The AMBER99 force field overestimates the population of syn conformations of the base orientation and of C2'-endo sugar puckering of the pyrimidines, while the AMBER99chi force field's predictions are more consistent with NMR results. Moreover, the AMBER99 force field prefers high anti conformations with glycosidic dihedral angles around 310 degrees for the base orientation of purines. The AMBER99chi force field prefers anti conformations around 185 degrees , which is more consistent with the quantum mechanical calculations and known 3D structures of folded ribonucleic acids (RNAs). Evidently, the AMBER99chi force field predicts the structural characteristics of ribonucleosides better than the AMBER99 force field and should improve structural and thermodynamic predictions of RNA structures.
Blümel, Marcus; Hooper, Scott L; Guschlbauerc, Christoph; White, William E; Büschges, Ansgar
2012-11-01
Characterizing muscle requires measuring such properties as force-length, force-activation, and force-velocity curves. These characterizations require large numbers of data points because both what type of function (e.g., linear, exponential, hyperbolic) best represents each property, and the values of the parameters in the relevant equations, need to be determined. Only a few properties are therefore generally measured in experiments on any one muscle, and complete characterizations are obtained by averaging data across a large number of muscles. Such averaging approaches can work well for muscles that are similar across individuals. However, considerable evidence indicates that large inter-individual variation exists, at least for some muscles. This variation poses difficulties for across-animal averaging approaches. Methods to fully describe all muscle's characteristics in experiments on individual muscles would therefore be useful. Prior work in stick insect extensor muscle has identified what functions describe each of this muscle's properties and shown that these equations apply across animals. Characterizing these muscles on an individual-by-individual basis therefore requires determining only the values of the parameters in these equations, not equation form. We present here techniques that allow determining all these parameter values in experiments on single muscles. This technique will allow us to compare parameter variation across individuals and to model muscles individually. Similar experiments can likely be performed on single muscles in other systems. This approach may thus provide a widely applicable method for characterizing and modeling muscles from single experiments.
Determination of solubility parameters for poly(3-hydroxyalkanoates).
Terada, M; Marchessault, R H
1999-01-01
The three dimensional solubility parameters defined by Hansen are based on dispersion forces between structural units, interaction between polar groups and hydrogen bonding. For polar polymers such as poly(3-hydroxyalkanoates), P(3HA), this approach was used to obtain the three coordinates of a solubility parameter in terms of: a dispersion part, a polar part and a hydrogen bonding part. Thirty-eight different solvents for poly(3-hydroxybutyrate), PHB, which are mentioned in the literature are examined by this method and the theoretical predictions are compared with the experimental reports. Another overall comparison between PHA polymers provides their Hansen and Hildebrand parameters for side chain lengths up to C13. In this series a linear progression in calculated solubility parameters with side chain length was found. An Appendix provides information and data on calculation of the solubility parameters. While the solubility information is limited and only covers homopolymers, it should help to highlight some of the contradictions regarding PHB solubility. This semi-empirical approach is only valid for amorphous polymers hence crystallinity effects, which are important with PHB, as well as molecular weight effects still require analysis.
Effective parameters determining the information flow in hierarchical biological systems.
Blöchl, Florian; Wittmann, Dominik M; Theis, Fabian J
2011-04-01
Signaling networks are abundant in higher organisms. They play pivotal roles, e.g., during embryonic development or within the immune system. In this contribution, we study the combined effect of the various kinetic parameters on the dynamics of signal transduction. To this end, we consider hierarchical complex systems as prototypes of signaling networks. For given topology, the output of these networks is determined by an interplay of the single parameters. For different kinetics, we describe this by algebraic expressions, the so-called effective parameters.When modeling switch-like interactions by Heaviside step functions, we obtain these effective parameters recursively from the interaction graph. They can be visualized as directed trees, which allows us to easily determine the global effect of single kinetic parameters on the system's behavior. We provide evidence that these results generalize to sigmoidal Hill kinetics.In the case of linear activation functions, we again show that the algebraic expressions can be immediately inferred from the topology of the interaction network. This allows us to transform time-consuming analytic solutions of differential equations into a simple graph-theoretic problem. In this context, we also discuss the impact of our work on parameter estimation problems. An issue is that even the fitting of identifiable effective parameters often turns out to be numerically ill-conditioned. We demonstrate that this fitting problem can be reformulated as the problem of fitting exponential sums, for which robust algorithms exist.
NASA Astrophysics Data System (ADS)
Lupyan, Dmitry; Abramov, Yuriy A.; Sherman, Woody
2012-11-01
The Cambridge Structural Database (CSD) offers an excellent data source to study small molecule conformations and molecular interactions. We have analyzed 130 small molecules from the CSD containing an intramolecular sulfur-oxygen distance less than the sum of their van der Waals (vdW) radii. Close S···O distances are observed in several important medicinal chemistry motifs (e.g. a carbonyl oxygen connected by a carbon or nitrogen linker to a sulfur) and are not treated well with existing parameters in the MMFFs or OPLS_2005 force fields, resulting in suboptimal geometries and energetics. In this work, we develop modified parameters for the OPLS_2005 force field to better treat this specific interaction in order to generate conformations close to those found in the CSD structures. We use a combination of refitting a force field torsional parameter, adding a specific atom pair vdW term, and attenuating the electrostatic interactions to obtain an improvement in the accuracy of geometry minimizations and conformational searches for these molecules. Specifically, in a conformational search 58 % of the cases produced a conformation less than 0.25 Å from the CSD crystal conformation with the modified OPLS force field parameters developed in this work. In contrast, 25 and 37 % produced a conformation less than 0.25 Å with the MMFFs and OPLS_2005 force fields, respectively. As an application of the new parameters, we generated conformations for the tyrosine kinase inhibitor axitinib (trade name Inlyta) that could be correctly repacked into three observed polymorphic structures, which was not possible with conformations generated using MMFFs or OPLS_2005. The improved parameters can be mapped directly onto physical characteristics of the systems that are treated inadequately with the molecular mechanics force fields used in this study and potentially other force fields as well.
Lupyan, Dmitry; Abramov, Yuriy A; Sherman, Woody
2012-11-01
The Cambridge Structural Database (CSD) offers an excellent data source to study small molecule conformations and molecular interactions. We have analyzed 130 small molecules from the CSD containing an intramolecular sulfur-oxygen distance less than the sum of their van der Waals (vdW) radii. Close S···O distances are observed in several important medicinal chemistry motifs (e.g. a carbonyl oxygen connected by a carbon or nitrogen linker to a sulfur) and are not treated well with existing parameters in the MMFFs or OPLS_2005 force fields, resulting in suboptimal geometries and energetics. In this work, we develop modified parameters for the OPLS_2005 force field to better treat this specific interaction in order to generate conformations close to those found in the CSD structures. We use a combination of refitting a force field torsional parameter, adding a specific atom pair vdW term, and attenuating the electrostatic interactions to obtain an improvement in the accuracy of geometry minimizations and conformational searches for these molecules. Specifically, in a conformational search 58 % of the cases produced a conformation less than 0.25 Å from the CSD crystal conformation with the modified OPLS force field parameters developed in this work. In contrast, 25 and 37 % produced a conformation less than 0.25 Å with the MMFFs and OPLS_2005 force fields, respectively. As an application of the new parameters, we generated conformations for the tyrosine kinase inhibitor axitinib (trade name Inlyta) that could be correctly repacked into three observed polymorphic structures, which was not possible with conformations generated using MMFFs or OPLS_2005. The improved parameters can be mapped directly onto physical characteristics of the systems that are treated inadequately with the molecular mechanics force fields used in this study and potentially other force fields as well.
Development of OPLS-AA Force Field Parameters for 68 Unique Ionic Liquids.
Sambasivarao, Somisetti V; Acevedo, Orlando
2009-04-14
OPLS-AA force field parameters have been developed and validated for use in the simulation of 68 unique combinations of room temperature ionic liquids featuring 1-alkyl-3-methylimidazolium [RMIM] (R = Me, Et, Bu, Hex, Oct), N-alkylpyridinium [RPyr], and choline cations, along with Cl(-), PF6(-), BF4(-), NO3(-), AlCl4(-), Al2Cl7(-), TfO(-), saccharinate, and acesulfamate anions. The new parameters were fit to conformational profiles from gas-phase ab initio calculations at the LMP2/cc-pVTZ(-f)//HF/6-31G(d) theory level and compared to experimental condensed-phase structural and thermodynamic data. Monte Carlo simulations of the ionic liquids gave relative deviations from experimental densities of ca. 1-3% at 25 °C for most combinations and also yielded close agreement over a temperature range of 5 to 90 °C. Predicted heats of vaporization compared well with available experimental data and estimates. Transferability of the new parameters to multiple alkyl side-chain lengths for [RMIM] and [RPyr] was determined to give excellent agreement with charges and torsion potentials developed specific to desired alkyl lengths in 35 separate ionic liquid simulations. As further validation of the newly developed parameters, the Kemp elimination reaction of benzisoxazole via piperidine was computed in 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] using mixed quantum and molecular mechanics (QM/MM) simulations and was found to give close agreement with the experimental free energy of activation.
NASA Astrophysics Data System (ADS)
Park, Boumyoung; Lee, Hyunseop; Kim, Youngjin; Kim, Hyoungjae; Jeong, Haedo
2008-12-01
The relationship between sliding friction and material removal was investigated using a sensor to measure dynamic friction force according to process parameters such as pressure, velocity, conditioning, abrasive concentration, and slurry pH during oxide chemical mechanical polishing (CMP). Friction force and material removal linearly depend on applied load and relative velocity. A high relative velocity also has an effect on the boundary condition between the wafer and the pad, and friction force reduces with increase in relative velocity. Friction force reduces with polishing time during oxide CMP with ex situ conditioning because of the changes in pad roughness parameters such as Ra, Rp, Rpk, and Rsk. Thus, the in situ conditioning method increases removal rate and improves nonuniformity. Friction force can be uniformly distributed on the oxide wafer as abrasive concentration increases owing to the reduction in friction force loaded on one abrasive particle, improving the nonuniformity of removal rate. In oxide CMP using alkali-based slurry, the effective formation and mechanical removal of the Si-OH bond layer on the SiO2 surface also affect the temporal decrease in friction force and result in a higher removal rate, in comparison with the results of a high friction force and a low removal rate in oxide CMP using neutral-based slurry.
Determination of the atrazine migration parameters in Vertisol
NASA Astrophysics Data System (ADS)
Raymundo-Raymundo, E.; Hernandez-Vargas, J.; Nikol'Skii, Yu. N.; Guber, A. K.; Gavi-Reyes, F.; Prado-Pano, B. L.; Figueroa-Sandoval, B.; Mendosa-Hernandez, J. R.
2010-05-01
The parameters of the atrazine migration in columns with undisturbed Vertisol sampled from an irrigated plot in Guanajuato, Mexico were determined. A model of the convection-dispersion transport of the chemical compounds accounting for the decomposition and equilibrium adsorption, which is widely applied for assessing the risk of contamination of natural waters with pesticides, was used. The model parameters were obtained by solving the inverse problem of the transport equation on the basis of laboratory experiments on the transport of the 18O isotope and atrazine in soil columns with an undisturbed structure at three filtration velocities. The model adequately described the experimental data at the individual selection of the parameters for each output curve. Physically unsubstantiated parameters of the atrazine adsorption and degradation were obtained when the parameter of the hydrodynamic dispersion was determined from the data on the 18O migration. The simulation also showed that the use of parameters obtained at water content close to saturation in the calculations for an unsaturated soil resulted in the overestimation of the leaching rate and the maximum concentration of atrazine in the output curve compared to the experimental data.
Automatic Determination of the Conic Coronal Mass Ejection Model Parameters
NASA Technical Reports Server (NTRS)
Pulkkinen, A.; Oates, T.; Taktakishvili, A.
2009-01-01
Characterization of the three-dimensional structure of solar transients using incomplete plane of sky data is a difficult problem whose solutions have potential for societal benefit in terms of space weather applications. In this paper transients are characterized in three dimensions by means of conic coronal mass ejection (CME) approximation. A novel method for the automatic determination of cone model parameters from observed halo CMEs is introduced. The method uses both standard image processing techniques to extract the CME mass from white-light coronagraph images and a novel inversion routine providing the final cone parameters. A bootstrap technique is used to provide model parameter distributions. When combined with heliospheric modeling, the cone model parameter distributions will provide direct means for ensemble predictions of transient propagation in the heliosphere. An initial validation of the automatic method is carried by comparison to manually determined cone model parameters. It is shown using 14 halo CME events that there is reasonable agreement, especially between the heliocentric locations of the cones derived with the two methods. It is argued that both the heliocentric locations and the opening half-angles of the automatically determined cones may be more realistic than those obtained from the manual analysis
Test stand for determining parameters of microbolometer camera
NASA Astrophysics Data System (ADS)
Krupiński, Michał; Bareła, Jarosław; Kastek, Mariusz; Chmielewski, Krzysztof
2016-10-01
In order to objectively compare the two infrared cameras ones must to measure and compare their parameters on a laboratory. One of the basic parameters for the evaluation of the designed camera is NEDT (noise equivalent delta temperature). In order to examine the NEDT ,parameters such as sensitivity and pixels noise must be measured. To do so, ones should register the output signal from the camera in response to the radiation of black bodies at two different temperatures. The article presents an application and measuring stand for determining the parameters of microbolometers camera. In addition to determination of parameters of a cameras the measuring stand allow to determine defective pixel map, the non uniformity correction (NUC) coefficients: 1-point and 2-point. Additionally, developed test stand serves as a test system to read the raw data from microbolometer detector. Captured image can be corrected with calculated non-uniformity correction coefficients. In a next step the image is processed and visualized on a monitor. Developed test stand allows for an initial assessment of the quality of designed readout circuit. It also allows for efficient testing and comparison of the number of sensors or readout circuits.
NASA Astrophysics Data System (ADS)
Mockler, E. M.; Chun, K. P.; Sapriza-Azuri, G.; Bruen, M.; Wheater, H. S.
2016-11-01
Predictions of river flow dynamics provide vital information for many aspects of water management including water resource planning, climate adaptation, and flood and drought assessments. Many of the subjective choices that modellers make including model and criteria selection can have a significant impact on the magnitude and distribution of the output uncertainty. Hydrological modellers are tasked with understanding and minimising the uncertainty surrounding streamflow predictions before communicating the overall uncertainty to decision makers. Parameter uncertainty in conceptual rainfall-runoff models has been widely investigated, and model structural uncertainty and forcing data have been receiving increasing attention. This study aimed to assess uncertainties in streamflow predictions due to forcing data and the identification of behavioural parameter sets in 31 Irish catchments. By combining stochastic rainfall ensembles and multiple parameter sets for three conceptual rainfall-runoff models, an analysis of variance model was used to decompose the total uncertainty in streamflow simulations into contributions from (i) forcing data, (ii) identification of model parameters and (iii) interactions between the two. The analysis illustrates that, for our subjective choices, hydrological model selection had a greater contribution to overall uncertainty, while performance criteria selection influenced the relative intra-annual uncertainties in streamflow predictions. Uncertainties in streamflow predictions due to the method of determining parameters were relatively lower for wetter catchments, and more evenly distributed throughout the year when the Nash-Sutcliffe Efficiency of logarithmic values of flow (lnNSE) was the evaluation criterion.
Javier, P.J.
1982-01-01
The variation of the pinning force with microstructure and with the Ginzburg-Landau parameter is studied for 53 vanadium and vanadium alloy specimens. Vanadium-carbide precipitates are used as pinning centers. The Ginzburg-Landau parameter is varied by alloying the vanadium with small quantities of gallium or niobium. Alloy compositions of V-0.20a/oGa, V-1.05a/oGa, V-2.96a/oGa, and V-4.01a/oNb are used. These yield a range of the Ginzburg-Landau parameter from less than 2 for the pure vanadium specimens, to more than 20 for the V-2.96a/oGa specimens. The pinning force is not described by a universal scaling law for all specimens. The pinning force for a specific reduced magnetic field is determined by the depinning mechanism active at that field. There are at least three depinning mechanisms. Two of these can be identified with the plastic-deformation mechanism and the line-pinning mechanism, which are predicted by Kramer. A previously unidentified depinning mechanism is the prevailing factor in specimens with large pinning centers. The empirical line-pinning force of the specimens varies with the individual precipitate volume cubed times the density of precipitates. The pinning force in the plastic-deformation region varies as the cube-root of the density of precipitates. A dependence on the Ginzburg-Landau parameter squared can be observed for the magnitude of the pinning force for most of the reduced field regions.
Frontal sinus parameters in computed tomography and sex determination.
Akhlaghi, Mitra; Bakhtavar, Khadijeh; Moarefdoost, Jhale; Kamali, Artin; Rafeifar, Shahram
2016-03-01
The frontal sinus is a sturdy part of the skull that is likely to be retrieved for forensic investigations. We evaluated frontal sinus parameters in paranasal sinus computed tomography (CT) images for sex determination. The study was conducted on 200 normal paranasal sinus CT images of 100 men and 100 women of Persian origin. We categorized the studied population into three age groups of 20-34, 35-49 and ⩾ 50 years. The number of partial septa in the right frontal sinus and the maximum height and width were significantly different between the two sexes. The highest precision for sex determination was for the maximum height of the left frontal sinus (61.3%). In the 20-34 years age-group, height and width of the frontal sinus were significantly different between the two sexes and the height of the left sinus had the highest precision (60.8%). In the 35-49 years age-group, right anterior-posterior diameter had a sex determination precision of 52.3%. No frontal sinus parameter reached a statistically significant level for sex determination in the ⩾ 50 years age-group. The number of septa and scallopings were not useful in sex determination. Frontal sinus parameters did not have a high precision in sex determination among Persian adults.
Global optimization of parameters in the reactive force field ReaxFF for SiOH.
Larsson, Henrik R; van Duin, Adri C T; Hartke, Bernd
2013-09-30
We have used unbiased global optimization to fit a reactive force field to a given set of reference data. Specifically, we have employed genetic algorithms (GA) to fit ReaxFF to SiOH data, using an in-house GA code that is parallelized across reference data items via the message-passing interface (MPI). Details of GA tuning turn-ed out to be far less important for global optimization efficiency than using suitable ranges within which the parameters are varied. To establish these ranges, either prior knowledge can be used or successive stages of GA optimizations, each building upon the best parameter vectors and ranges found in the previous stage. We have finally arrive-ed at optimized force fields with smaller error measures than those published previously. Hence, this optimization approach will contribute to converting force-field fitting from a specialist task to an everyday commodity, even for the more difficult case of reactive force fields.
QCD-inspired determination of NJL model parameters
NASA Astrophysics Data System (ADS)
Springer, Paul; Braun, Jens; Rechenberger, Stefan; Rennecke, Fabian
2017-03-01
The QCD phase diagram at finite temperature and density has attracted considerable interest over many decades now, not least because of its relevance for a better understanding of heavy-ion collision experiments. Models provide some insight into the QCD phase structure but usually rely on various parameters. Based on renormalization group arguments, we discuss how the parameters of QCD low-energy models can be determined from the fundamental theory of the strong interaction. We particularly focus on a determination of the temperature dependence of these parameters in this work and comment on the effect of a finite quark chemical potential. We present first results and argue that our findings can be used to improve the predictive power of future model calculations.
Determination of Complex Microcalorimeter Parameters with Impedance Measurements
NASA Technical Reports Server (NTRS)
Saab, T.; Bandler, S. R.; Chervenak, J.; Figueroa-Feliciano, E.; Finkbeiner, F.; Iyomoto, N.; Kelley, R.; Kilbourne, C. A.; Lindeman, M. A.; Porter, F. S.; Sadleir, J.
2005-01-01
The proper understanding and modeling of a microcalorimeter s response requires the accurate knowledge of a handful of parameters, such as C, G, alpha, . . . . While a few of these, such 8s the normal state resistance and the total thermal conductance to the heat bath (G) are directly determined from the DC IV characteristics, some others, notoriously the heat capacity (C) and alpha, appear in degenerate combinations in most measurable quantities. The case of a complex microcalorimeter, i.e. one in which the absorber s heat capacity is connected by a finite thermal impedance to the sensor, and subsequently by another thermal impedance to the heat bath, results in an added ambiguity in the determination of the individual C's and G's. In general, the dependence of the microcalorimeter s complex impedance on these parameters varies with frequency. This variation allows us to determine the individual parameters by fitting the prediction of the microcalorimeter model to the impedance data. We describe in this paper our efforts at characterizing the Goddard X-ray microcalorimeters. Using the parameters determined with this method we them compare the pulse shape and noise spectra predicted by the microcalorimeter model to data taken with the same devices.
Determination of Parameters of PV Concentrating System With Heliostat
NASA Astrophysics Data System (ADS)
Vardanyan, R.; Norsoyan, A.; Dallakyan, V.
2010-10-01
The structure of PV concentrating system with heliostat is analyzed. The mathematical model of system consisting of PV concentrating module and heliostat is developed. With the use of developed mathematical model the optimal parameters of the system are determined. The results of this work can be used during the design of PV concentrating systems with heliostats.
Intermolecular potential parameters and combining rules determined from viscosity data
Bastien, Lucas A.J.; Price, Phillip N.; Brown, Nancy J.
2010-05-07
The Law of Corresponding States has been demonstrated for a number of pure substances and binary mixtures, and provides evidence that the transport properties viscosity and diffusion can be determined from a molecular shape function, often taken to be a Lennard-Jones 12-6 potential, that requires two scaling parameters: a well depth {var_epsilon}{sub ij} and a collision diameter {sigma}{sub ij}, both of which depend on the interacting species i and j. We obtain estimates for {var_epsilon}{sub ij} and {sigma}{sub ij} of interacting species by finding the values that provide the best fit to viscosity data for binary mixtures, and compare these to calculated parameters using several 'combining rules' that have been suggested for determining parameter values for binary collisions from parameter values that describe collisions of like molecules. Different combining rules give different values for {sigma}{sub ij} and {var_epsilon}{sub ij} and for some mixtures the differences between these values and the best-fit parameter values are rather large. There is a curve in ({var_epsilon}{sub ij}, {sigma}{sub ij}) space such that parameter values on the curve generate a calculated viscosity in good agreement with measurements for a pure gas or a binary mixture. The various combining rules produce couples of parameters {var_epsilon}{sub ij}, {sigma}{sub ij} that lie close to the curve and therefore generate predicted mixture viscosities in satisfactory agreement with experiment. Although the combining rules were found to underpredict the viscosity in most of the cases, Kong's rule was found to work better than the others, but none of the combining rules consistently yields parameter values near the best-fit values, suggesting that improved rules could be developed.
Application of Novel Lateral Tire Force Sensors to Vehicle Parameter Estimation of Electric Vehicles
Nam, Kanghyun
2015-01-01
This article presents methods for estimating lateral vehicle velocity and tire cornering stiffness, which are key parameters in vehicle dynamics control, using lateral tire force measurements. Lateral tire forces acting on each tire are directly measured by load-sensing hub bearings that were invented and further developed by NSK Ltd. For estimating the lateral vehicle velocity, tire force models considering lateral load transfer effects are used, and a recursive least square algorithm is adapted to identify the lateral vehicle velocity as an unknown parameter. Using the estimated lateral vehicle velocity, tire cornering stiffness, which is an important tire parameter dominating the vehicle’s cornering responses, is estimated. For the practical implementation, the cornering stiffness estimation algorithm based on a simple bicycle model is developed and discussed. Finally, proposed estimation algorithms were evaluated using experimental test data. PMID:26569246
Nam, Kanghyun
2015-11-11
This article presents methods for estimating lateral vehicle velocity and tire cornering stiffness, which are key parameters in vehicle dynamics control, using lateral tire force measurements. Lateral tire forces acting on each tire are directly measured by load-sensing hub bearings that were invented and further developed by NSK Ltd. For estimating the lateral vehicle velocity, tire force models considering lateral load transfer effects are used, and a recursive least square algorithm is adapted to identify the lateral vehicle velocity as an unknown parameter. Using the estimated lateral vehicle velocity, tire cornering stiffness, which is an important tire parameter dominating the vehicle's cornering responses, is estimated. For the practical implementation, the cornering stiffness estimation algorithm based on a simple bicycle model is developed and discussed. Finally, proposed estimation algorithms were evaluated using experimental test data.
Zheng, Suqing; Tang, Qing; He, Jian; Du, Shiyu; Xu, Shaofang; Wang, Chaojie; Xu, Yong; Lin, Fu
2016-04-25
Force fields are fundamental to molecular dynamics simulations. However, the incompleteness of force field parameters has been a long-standing problem, especially for metal-related systems. In our previous work, we adopted the Seminario method based on the Hessian matrix to systematically derive the zinc-related force field parameters for AMBER. In this work, in order to further simplify the whole protocol, we have implemented a user-friendly Visual Force Field Derivation Toolkit (VFFDT) to derive the force field parameters via simply clicking on the bond or angle in the 3D viewer, and we have further extended our previous program to support the Hessian matrix output from a variety of quantum mechanics (QM) packages, including Gaussian 03/09, ORCA 3.0, QChem, GAMESS-US, and MOPAC 2009/2012. In this toolkit, a universal VFFDT XYZ file format containing the raw Hessian matrix is available for all of the QM packages, and an instant force field parametrization protocol based on a semiempirical quantum mechanics (SQM) method is introduced. The new function that can automatically obtain the relevant parameters for zinc, copper, iron, etc., which can be exported in AMBER Frcmod format, has been added. Furthermore, our VFFDT program can read and write files in AMBER Prepc, AMBER Frcmod, and AMBER Mol2 format and can also be used to customize, view, copy, and paste the force field parameters in the context of the 3D viewer, which provides utilities complementary to ANTECHAMBER, MCPB, and MCPB.py in the AmberTools.
Frank, T D; Friedrich, R; Beek, P J
2006-11-01
We address two questions that are central to understanding human motor control variability: what kind of dynamical components contribute to motor control variability (i.e., deterministic and/or random ones), and how are those components structured? To this end, we derive a stochastic order parameter equation for isometric force production from experimental data using drift-diffusion estimates. We show that the force variability increases with the required force output because of a decrease of deterministic stability and an accompanying increase of noise intensity. A structural analysis reveals that the deterministic component consists of a linear control loop, while the random component involves a noise source that scales with force output. In addition, we present evidence for the existence of a subject-independent overall noise level of human isometric force production.
NASA Astrophysics Data System (ADS)
Aioanei, Daniel; Samorì, Bruno; Brucale, Marco
2009-12-01
Single molecule force spectroscopy (SMFS) is extensively used to characterize the mechanical unfolding behavior of individual protein domains under applied force by pulling chimeric polyproteins consisting of identical tandem repeats. Constant velocity unfolding SMFS data can be employed to reconstruct the protein unfolding energy landscape and kinetics. The methods applied so far require the specification of a single stretching force increase function, either theoretically derived or experimentally inferred, which must then be assumed to accurately describe the entirety of the experimental data. The very existence of a suitable optimal force model, even in the context of a single experimental data set, is still questioned. Herein, we propose a maximum likelihood (ML) framework for the estimation of protein kinetic parameters which can accommodate all the established theoretical force increase models. Our framework does not presuppose the existence of a single force characteristic function. Rather, it can be used with a heterogeneous set of functions, each describing the protein behavior in the stretching time range leading to one rupture event. We propose a simple way of constructing such a set of functions via piecewise linear approximation of the SMFS force vs time data and we prove the suitability of the approach both with synthetic data and experimentally. Additionally, when the spontaneous unfolding rate is the only unknown parameter, we find a correction factor that eliminates the bias of the ML estimator while also reducing its variance. Finally, we investigate which of several time-constrained experiment designs leads to better estimators.
Analysis of kinematic data and determination of ground reaction force of foot in slow squat
NASA Astrophysics Data System (ADS)
Zhang, Xu-Shu; Guo, Yuan; An, Mei-Wen; Chen, Wei-Yi
2013-02-01
In the present paper, the ground reaction force (GRF) acting on foot in slow squat was determined through a force measuring system, and at the same time, the kinematic data of human squat were obtained by analyzing the photographed image sequences. According to the height and body weight, six healthy volunteers were selected, three men in one group and the other three women in another group, and the fundamental parameters of subjects were recorded, including body weight, height and age, etc. Based on the anatomy characteristics, some markers were placed on the right side of joints. While the subject squatted at slow speed on the force platform, the ground reaction forces on the forefoot and heel for each foot were obtained through calibrated force platform. The analysis results show that the reaction force on heel is greater than that on forefoot, and double feet have nearly constant force. Moreover, from processing and analyzing the synchronously photographed image sequences in squat, the kinematic data of human squat were acquired, including mainly the curves of angle, angular velocity and angular acceleration varied with time for knee, hip and ankle joints in a sagittal plane. The obtained results can offer instructive reference for photographing and analyzing the movements of human bodies, diagnosing some diseases, and establishing in the future appropriate mathematical models for the human motion.
Coefficients of an analytical aerosol forcing equation determined with a Monte-Carlo radiation model
NASA Astrophysics Data System (ADS)
Hassan, Taufiq; Moosmüller, H.; Chung, Chul E.
2015-10-01
Simple analytical equations for global-average direct aerosol radiative forcing are useful to quickly estimate aerosol forcing changes as function of key atmosphere, surface and aerosol parameters. The surface and atmosphere parameters in these analytical equations are the globally uniform atmospheric transmittance and surface albedo, and have so far been estimated from simplified observations under untested assumptions. In the present study, we take the state-of-the-art analytical equation and write the aerosol forcing as a linear function of the single scattering albedo (SSA) and replace the average upscatter fraction with the asymmetry parameter (ASY). Then we determine the surface and atmosphere parameter values of this equation using the output from the global MACR (Monte-Carlo Aerosol Cloud Radiation) model, as well as testing the validity of the equation. The MACR model incorporated spatio-temporally varying observations for surface albedo, cloud optical depth, water vapor, stratosphere column ozone, etc., instead of assuming as in the analytical equation that the atmosphere and surface parameters are globally uniform, and should thus be viewed as providing realistic radiation simulations. The modified analytical equation needs globally uniform aerosol parameters that consist of AOD (Aerosol Optical Depth), SSA, and ASY. The MACR model is run here with the same globally uniform aerosol parameters. The MACR model is also run without cloud to test the cloud effect. In both cloudy and cloud-free runs, the equation fits in the model output well whether SSA or ASY varies. This means the equation is an excellent approximation for the atmospheric radiation. On the other hand, the determined parameter values are somewhat realistic for the cloud-free runs but unrealistic for the cloudy runs. The global atmospheric transmittance, one of the determined parameters, is found to be around 0.74 in case of the cloud-free conditions and around 1.03 with cloud. The surface
Method of determining forest production from remotely sensed forest parameters
Corey, J.C.; Mackey, H.E. Jr.
1987-08-31
A method of determining forest production entirely from remotely sensed data in which remotely sensed multispectral scanner (MSS) data on forest 5 composition is combined with remotely sensed radar imaging data on forest stand biophysical parameters to provide a measure of forest production. A high correlation has been found to exist between the remotely sensed radar imaging data and on site measurements of biophysical 10 parameters such as stand height, diameter at breast height, total tree height, mean area per tree, and timber stand volume.
Determining optimal parameters in magnetic spacecraft stabilization via attitude feedback
NASA Astrophysics Data System (ADS)
Bruni, Renato; Celani, Fabio
2016-10-01
The attitude control of a spacecraft using magnetorquers can be achieved by a feedback control law which has four design parameters. However, the practical determination of appropriate values for these parameters is a critical open issue. We propose here an innovative systematic approach for finding these values: they should be those that minimize the convergence time to the desired attitude. This a particularly diffcult optimization problem, for several reasons: 1) such time cannot be expressed in analytical form as a function of parameters and initial conditions; 2) design parameters may range over very wide intervals; 3) convergence time depends also on the initial conditions of the spacecraft, which are not known in advance. To overcome these diffculties, we present a solution approach based on derivative-free optimization. These algorithms do not need to write analytically the objective function: they only need to compute it in a number of points. We also propose a fast probing technique to identify which regions of the search space have to be explored densely. Finally, we formulate a min-max model to find robust parameters, namely design parameters that minimize convergence time under the worst initial conditions. Results are very promising.
Determination of Solubility Parameters of Ibuprofen and Ibuprofen Lysinate.
Kitak, Teja; Dumičić, Aleksandra; Planinšek, Odon; Šibanc, Rok; Srčič, Stanko
2015-12-03
In recent years there has been a growing interest in formulating solid dispersions, which purposes mainly include solubility enhancement, sustained drug release and taste masking. The most notable problem by these dispersions is drug-carrier (in)solubility. Here we focus on solubility parameters as a tool for predicting the solubility of a drug in certain carriers. Solubility parameters were determined in two different ways: solely by using calculation methods, and by experimental approaches. Six different calculation methods were applied in order to calculate the solubility parameters of the drug ibuprofen and several excipients. However, we were not able to do so in the case of ibuprofen lysinate, as calculation models for salts are still not defined. Therefore, the extended Hansen's approach and inverse gas chromatography (IGC) were used for evaluating of solubility parameters for ibuprofen lysinate. The obtained values of the total solubility parameter did not differ much between the two methods: by the extended Hansen's approach it was δt = 31.15 MPa(0.5) and with IGC it was δt = 35.17 MPa(0.5). However, the values of partial solubility parameters, i.e., δd, δp and δh, did differ from each other, what might be due to the complex behaviour of a salt in the presence of various solvents.
Silicone hydrogel contact lens surface analysis by atomic force microscopy: shape parameters
NASA Astrophysics Data System (ADS)
Giraldez, M. J.; Garcia-Resua, C.; Lira, M.; Sánchez-Sellero, C.; Yebra-Pimentel, E.
2011-05-01
Purpose: Average roughness (Ra) is generally used to quantify roughness; however it makes no distinction between spikes and troughs. Shape parameters as kurtosis (Rku) and skewness (Rsk) serve to distinguish between two profiles with the same Ra. They have been reported in many biomedical fields, but they were no applied to contact lenses before. The aim of this study is to analyze surface properties of four silicone hydrogel contact lenses (CL) by Atomic Force Microscopy (AFM) evaluating Ra, Rku and Rsk. Methods: CL used in this study were disposable silicone hydrogel senofilcon A, comfilcon A, balafilcon A and lotrafilcon B. Unworn CL surfaces roughness and topography were measured by AFM (Veeco, multimode-nanoscope V) in tapping modeTM. Ra, Rku and Rsk for 25 and 196 μm2 areas were determined. Results: Surface topography and parameters showed different characteristics depending on the own nature of the contact lens (Ra/Rku/Rsk for 25 and 196 μm2 areas were: senofilcon A 3,33/3,74/0,74 and 3,76/18,16/1,75; comfilcon A: 1,56/31,09/2,93 and 2,76/45,82/3,60; balafilcon A: 2,01/33,62/-2,14 and 2,54/23,36/-1,96; lotrafilcon B: 26,97/4,11/-0,34 and 29,25/2,82/-0,23). In lotrafilcon B, with the highest Ra, Rku showed a lower degree of peakedness of its distribution. Negative Rsk value obtained for balafilcon A showed a clear predominance of valleys in this lens. Conclusions: Kku and Rsk are two statistical parameters useful to analyse CL surfaces, which complete information from Ra. Differences in values distribution and symmetry were observed between CL.
Determining the alpha dynamo parameter in incompressible homogeneous magnetohydrodynamic turbulence
NASA Technical Reports Server (NTRS)
Matthaeus, W. H.; Goldstein, M. L.; Lantz, S. R.
1983-01-01
Alpha, an important parameter in dynamo theory, is proportional to either the kinetic, current, magnetic, or velocity helicity of the fluctuating magnetic field and fluctuating velocity field. The particular helicity to which alpha is proportional depends on the assumptions used in deriving the first order smoothed equations that describe the alpha effect. In two cases, when alpha is proportional to either the magnetic helicity or velocity helicity, alpha is determined experimentally from two point measurements of the fluctuating fields in incompressible, homogeneous turbulence having arbitrary symmetry. For the other two possibilities, alpha is determined if the turbulence is isotropic.
Spectral Determination of Source Parameters in The Marmara Region
NASA Astrophysics Data System (ADS)
Koseoglu, A.; Meral Ozel, N.; Barıs, S.
2014-12-01
Ever since the 1999 Kocaeli Earthquake, in which the Kandilli Observatory and Earthquake Research Institute (KOERI) was not able to correctly reflect the magnitude size in its preliminary report because of the saturation effect, a rapid and accurate determination of the earthquake becomes a very important issue. Therefore, in the framework of this study an automatic determination of the moment magnitude was performed by using the displacement spectra of selected earthquakes in Marmara Region. For this purpose 39 three component broadband stations from KOERI seismic network which recorded 174 earthquakes with magnitudes 2.5≤M≤5.0 in between 2006-2009 were used. Due to the importance of quality factor in determination of the moment magnitude with spectral analysis method, the quality factor was calculated for the whole region in the beginning. Source spectrum which was obtained by converting the velocity records to displacement spectra and moment magnitudes of earthquakes were determined by fitting this spectrum to classical Brune model. For this aim, an automatic procedure was utilized which based on minimizing the differences between observed and synthetic source spectra identified by the S-waves. Besides of moment magnitude and location parameters, some source parameters such as seismic moment, spectral level, corner frequency and stress drop were also calculated. Application of the method proves that determine the seismic moment from the source spectra is applicable not only for earthquakes with small magnitude but also moderate earthquakes as well.
Effect of hinge-moment parameters on elevator stick forces in rapid maneuvers
NASA Technical Reports Server (NTRS)
Jones, Robert T; Greenberg, Harry
1944-01-01
The importance of the stick force per unit normal acceleration as a criterion of longitudinal stability and the critical dependence of this gradient on elevator hinge-moment parameters have been shown in previous reports. The present report continues the investigation with special reference to transient effects for maneuvers of short duration.
Ervik, Åsmund; Mejía, Andrés; Müller, Erich A
2016-09-26
Coarse-grained molecular simulation has become a popular tool for modeling simple and complex fluids alike. The defining aspects of a coarse grained model are the force field parameters, which must be determined for each particular fluid. Because the number of molecular fluids of interest in nature and in engineering processes is immense, constructing force field parameter tables by individually fitting to experimental data is a futile task. A step toward solving this challenge was taken recently by Mejía et al., who proposed a correlation that provides SAFT-γ Mie force field parameters for a fluid provided one knows the critical temperature, the acentric factor and a liquid density, all relatively accessible properties. Building on this, we have applied the correlation to more than 6000 fluids, and constructed a web application, called "Bottled SAFT", which makes this data set easily searchable by CAS number, name or chemical formula. Alternatively, the application allows the user to calculate parameters for components not present in the database. Once the intermolecular potential has been found through Bottled SAFT, code snippets are provided for simulating the desired substance using the "raaSAFT" framework, which leverages established molecular dynamics codes to run the simulations. The code underlying the web application is written in Python using the Flask microframework; this allows us to provide a modern high-performance web app while also making use of the scientific libraries available in Python. Bottled SAFT aims at taking the complexity out of obtaining force field parameters for a wide range of molecular fluids, and facilitates setting up and running coarse-grained molecular simulations. The web application is freely available at http://www.bottledsaft.org . The underlying source code is available on Bitbucket under a permissive license.
NASA Technical Reports Server (NTRS)
Jaffe, Richard; Langhoff, Stephen R. (Technical Monitor)
1995-01-01
Ab initio quantum chemistry calculations for model molecules can be used to parameterize force fields for molecular dynamics simulations of polymers. Emphasis in our research group is on using quantum chemistry-based force fields for molecular dynamics simulations of organic polymers in the melt and glassy states, but the methodology is applicable to simulations of small molecules, multicomponent systems and solutions. Special attention is paid to deriving reliable descriptions of the non-bonded and electrostatic interactions. Several procedures have been developed for deriving and calibrating these parameters. Our force fields for aromatic polyimide simulations will be described. In this application, the intermolecular interactions are the critical factor in determining many properties of the polymer (including its color).
NASA Technical Reports Server (NTRS)
Poggio, A. J.; Burke, G. L.; Pennock, S. T.
1995-01-01
This report describes the experimental and analytical efforts performed to determine the constitutive parameters of a reinforced concrete pad on which an aircraft (the NASA Boeing 757) was parked while its internal electromagnetic environment was measured. This concrete pad is part of the Large Electromagnetic System-Level Illuminator (LESLI) test facility at the Phillips Laboratory, Kirtland Air Force Base, New Mexico. The relative dielectric constant, conductivity, index of refraction, and reflection coefficient have been determined over the frequency range of 0 to 300 MHz and are presented.
Visscher, Koen M; Vosmeer, C Ruben; Luirink, Rosa A; Geerke, Daan P
2017-03-30
In this work, parameters are optimized for a charge-on-spring based polarizable force field for linear alcohols. We show that parameter transferability can be obtained using a systematic approach in which the effects of parameter changes on physico-chemical properties calculated from simulation are predicted. Our previously described QM/MM calculations are used to attribute condensed-phase polarizabilities, and starting from the non-polarizable GROMOS 53A5/53A6 parameter set, van der Waals and Coulomb interaction parameters are optimized to reproduce pure-liquid (thermodynamic, dielectric, and transport) properties, as well as hydration free energies. For a large set of models, which were obtained by combining small perturbations of 10 distinct parameters, values for pure-liquid properties of the series methanol to butanol were close to experiment. From this large set of models, we selected 34 models without special repulsive van der Waals parameters to distinguish between hydrogen-bonding and non-hydrogen-bonding atom pairs, to make the force field simple and transparent. © 2017 Wiley Periodicals, Inc.
[Parameter determination of algae growth based on ecological tank experiment].
Pang, Yong; Ding, Ling; Gao, Guang
2005-05-01
A dynamic simulation experiment of algae in an ecological tank was performed at the Taihu Laboratory for Lake Ecosystem Research. During the experiment, water from Taihu Lake was infused into the ecological tank and samples were taken continually to observe algae growth under varying conditions, such as temperature, sunlight and nutrients. Based on the experiment, an algae growth model, considering nitrogen and phosphorus cycle, was developed by using the advanced PHREEQC model. After that, a detailed calibration and validation of parameters in the model were done on the basis of experimental results. The least square method was used to determine the optimal set of parameters. The calculated values of algae and nutrient concentrations show fairly satisfying fittness with measured data.
Determination of critical anthropometric parameters for design of respirators
You-Hin Liau
1982-12-01
Anthropometric data were collected from 243 workers in a respirator fit-test programme, and an attempt was made to determine a correlation between these data and the Protection Factor obtained from quantitative fit-testing for half-mask respirators. Data were collected for two direct and five indirect facial measurements from front- and side-view slides of test subjects. For analysis, the data were normalized with relevant respirators dimensions (4 brands and 10 sizes). Results of linear regression analysis indicated that correlation coefficients between Protection Factor and anthropometric data (face length, mouth width, face width, nasal root breadth) were, respectively, 0.04, 0.22, 0.30 and 0.04. These correlation coefficients are for white males without facial hair. The analysis showed the 'critical' parameters to be mouth width and face width; however, a person with certain combinations of anthropometric parameters may provide a better correlation with Protection Factor.
Global Cosmological Parameters Determined Using Classical Double Radio Galaxies
NASA Astrophysics Data System (ADS)
Guerra, Erick J.; Daly, Ruth A.; Wan, Lin
2000-12-01
A sample of 20 powerful extended radio galaxies with redshifts between zero and 2 were used to determine constraints on global cosmological parameters. Data for six radio sources were obtained from the VLA archive, analyzed, and combined with the sample of 14 radio galaxies used previously by Guerra & Daly to determine cosmological parameters. The new results are consistent with our previous results, and indicate that the current value of the mean mass density of the universe is significantly less than the critical value. A universe with Ωm of unity in matter is ruled out at 99.0% confidence, and the best-fitting values of Ωm in matter are 0.10+0.25-0.10 and -0.25+0.35-0.25 assuming zero space curvature and zero cosmological constant, respectively. Note that identical results obtain when the low-redshift bin, which includes Cygnus A, is excluded; these results are independent of whether the radio source Cygnus A is included. The method does not rely on a zero-redshift normalization. The radio properties of each source are also used to determine the density of the gas in the vicinity of the source, and the beam power of the source. The six new radio sources have physical characteristics similar to those found for the original 14 sources. The density of the gas around these radio sources is typical of gas in present-day clusters of galaxies. The beam powers are typically about 1045 ergs s-1.
McCarty, Rachael; Nima Mahmoodi, S.
2014-02-21
The equations of motion for a piezoelectric microcantilever are derived for a nonlinear contact force. The analytical expressions for natural frequencies and mode shapes are obtained. Then, the method of multiple scales is used to analyze the analytical frequency response of the piezoelectric probe. The effects of nonlinear excitation force on the microcantilever beam's frequency and amplitude are analytically studied. The results show a frequency shift in the response resulting from the force nonlinearities. This frequency shift during contact mode is an important consideration in the modeling of AFM mechanics for generation of more accurate imaging. Also, a sensitivity analysis of the system parameters on the nonlinearity effect is performed. The results of a sensitivity analysis show that it is possible to choose parameters such that the frequency shift minimizes. Certain parameters such as tip radius, microcantilever beam dimensions, and modulus of elasticity have more influence on the nonlinearity of the system than other parameters. By changing only three parameters—tip radius, thickness, and modulus of elasticity of the microbeam—a more than 70% reduction in nonlinearity effect was achieved.
A Database of Force-Field Parameters, Dynamics, and Properties of Antimicrobial Compounds.
Malloci, Giuliano; Vargiu, Attilio Vittorio; Serra, Giovanni; Bosin, Andrea; Ruggerone, Paolo; Ceccarelli, Matteo
2015-08-03
We present an on-line database of all-atom force-field parameters and molecular properties of compounds with antimicrobial activity (mostly antibiotics and some beta-lactamase inhibitors). For each compound, we provide the General Amber Force Field parameters for the major species at physiological pH, together with an analysis of properties of interest as extracted from µs-long molecular dynamics simulations in explicit water solution. The properties include number and population of structural clusters, molecular flexibility, hydrophobic and hydrophilic molecular surfaces, the statistics of intraand inter-molecular H-bonds, as well as structural and dynamical properties of solvent molecules within first and second solvation shells. In addition, the database contains several key molecular parameters, such as energy of the frontier molecular orbitals, vibrational properties, rotational constants, atomic partial charges and electric dipole moment, computed by Density Functional Theory. The present database (to our knowledge the first extensive one including dynamical properties) is part of a wider project aiming to build-up a database containing structural, physico-chemical and dynamical properties of medicinal compounds using different force-field parameters with increasing level of complexity and reliability. The database is freely accessible at http://www.dsf.unica.it/translocation/db/.
Determination of diffusion rate parameters in unequilibrated systems
Kohls, J.F.
1980-05-06
A mathematical method of determining the required rate parameters has been developed using the unequilibrated portion of the throughput rate curve. The developed method, termed the stabilized search method, has been verified against both simulated data and actual experimental equilibrated data. Studies performed with simulated permeation data demonstrate that the accuracy of the determined parameters is dependent upon the accuracy of the data used. To quantitatively assess the accuracy of the stabilized search method, several values of diffusivity were used to generate groups of simulated permeation data, each with known solubility and magnitude of random error. The magnitudes of the errors used were chosen to approximate actual experimental permeation rate data. Each group of data was then analyzed using the stabilized search method. The accuracy of the method was evaluated using the calculated diffusivity, solubility, and permeability values in comparison to their actual values. Results showed that the value of diffusivity generated from the data is tolerant of random errors and can be accurately evaluated from data with a 20 percent random error component. The solubility and permeability values are more sensitive to random error. The accuracy to which they can be determined is approximately equal to the random error. Several other modes of error encroachment are discussed and their relative contributions to the possible overall error assessed. A prediction of parameters was made from six sets of experimental permeation data; data was gathered using a leak detector with a 10 to 20% experimental error. Predicted parametric values yield calculated equilibrium throughputs with an average error of 15%.
Semi-empirical determination of radiative parameters for atomic nickel
NASA Astrophysics Data System (ADS)
Ruczkowski, J.; Elantkowska, M.; Dembczyński, J.
2017-01-01
The aim of this article is to determine the values of the radiative parameters for atomic nickel by means of a semi-empirical method. The calculated values of oscillator strengths and lifetimes are, in the majority of cases, in good agreement with experimental data. Our calculation procedures allowed us to obtain the values of transition integrals and predict the values of oscillator strengths for transitions over a wide spectral range and radiative lifetimes for excited levels. Furthermore, the predicted values will be useful when the experimental values are not known.
NASA Astrophysics Data System (ADS)
Urs, Thejas G.; Gowtham, G. K.; Nandaprakash, M. B.; Mahadevaiah, D.; Sangappa, Y.; Somashekar, R.
2017-01-01
A model to determine refractive index and the intermolecular force constant in a polymeric chain is presented in this study. We have used the UV/visible absorption spectrum of a sample to determine afore mentioned parameters. The exponential absorption wavelength points of the spectrum are used to determine these parameters, on which the optical band gap of the material is defined. This study is carried out for various dopant concentration of a composite, so as to get a comparative insight. This study reveals the dependence of these parameters on dopant concentration and the wavelength.
Lee, Ayoung; Jin, Howon; Dang, Hyun-Woo; Choi, Kyung-Hyun; Ahn, Kyung Hyun
2013-11-05
The harmony of ink and printing method is of importance in producing on-demand droplets and jets of ink. Many factors including the material properties, the processing conditions, and the nozzle geometry affect the printing quality. In electrohydrodynamic (EHD) printing where droplets or jets are generated by the electrostatic force, the physical as well as the electrical properties of the fluid should be taken into account to achieve the desired performance. In this study, a systematic approach was suggested for finding the processing windows of the EHD printing. Six dimensionless parameters were organized and applied to the printing system of ethanol/terpineol mixtures. On the basis of the correlation of the dimensionless voltage and the charge relaxation length, the jet diameter of cone-jet mode was characterized, and the semicone angle was compared with the theoretical Taylor angle. In addition, the ratio of electric normal force and electric tangential force on the charged surface of the Taylor cone was recommended as a parameter that determines the degree of cone-jet stability. The cone-jet became more stable as this ratio got smaller. This approach was a systematic and effective way of obtaining the Taylor cone of the cone-jet mode and evaluating the jetting stability. The control of the inks with optimized experimental parameters by this method will improve the jetting performance in EHD inkjet printing.
Determining prestressing forces for inspection of prestressed concrete containments
Not Available
1990-07-01
General Design Criterion 53, Provisions for Containment Testing and Inspection,'' of Appendix A, General Design Criteria for Nuclear Power Plants,'' to 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities,'' requires, in part, that the reactor containment be designed to permit (1) periodic inspection of all important areas and (2) an appropriate surveillance program. Regulatory Guide 1.35, Inservice Inspection of Ungrouted Tendons in Prestressed Concrete Containment Structures,'' describes a basis acceptable to the NRC staff for developing an appropriate inservice inspection and surveillance program for ungrouted tendons in prestressed concrete containment structures of light-water-cooled reactors. This guide expands and clarifies the NRC staff position on determining prestressing forces to be used for inservice inspections of prestressed concrete containment structures.
Scintillating bolometers: A key for determining WIMP parameters
NASA Astrophysics Data System (ADS)
Cerdeño, D. G.; Marcos, C.; Peiró, M.; Fornasa, M.; Cuesta, C.; García, E.; Ginestra, C.; Martínez, M.; Ortigoza, Y.; Puimedón, J.; Sarsa, M. L.
2014-07-01
In the last decade direct detection Dark Matter (DM) experiments have increased enormously their sensitivity and ton-scale setups have been proposed, especially using germanium and xenon targets with double readout and background discrimination capabilities. In light of this situation, we study the prospects for determining the parameters of Weakly Interacting Massive Particle (WIMP) DM (mass, spin-dependent (SD) and spin-independent (SI) cross-section off nucleons) by combining the results of such experiments in the case of a hypothetical detection. In general, the degeneracy between the SD and SI components of the scattering cross-section can only be removed using targets with different sensitivities to these components. Scintillating bolometers, with particle discrimination capability, very good energy resolution and threshold and a wide choice of target materials, are an excellent tool for a multitarget complementary DM search. We investigate how the simultaneous use of scintillating targets with different SD-SI sensitivities and/or light isotopes (as the case of CaF2 and NaI) significantly improves the determination of the WIMP parameters. In order to make the analysis more realistic we include the effect of uncertainties in the halo model and in the spin-dependent nuclear structure functions, as well as the effect of a thermal quenching different from 1.
Filter parameter tuning analysis for operational orbit determination support
NASA Technical Reports Server (NTRS)
Dunham, J.; Cox, C.; Niklewski, D.; Mistretta, G.; Hart, R.
1994-01-01
The use of an extended Kalman filter (EKF) for operational orbit determination support is being considered by the Goddard Space Flight Center (GSFC) Flight Dynamics Division (FDD). To support that investigation, analysis was performed to determine how an EKF can be tuned for operational support of a set of earth-orbiting spacecraft. The objectives of this analysis were to design and test a general purpose scheme for filter tuning, evaluate the solution accuracies, and develop practical methods to test the consistency of the EKF solutions in an operational environment. The filter was found to be easily tuned to produce estimates that were consistent, agreed with results from batch estimation, and compared well among the common parameters estimated for several spacecraft. The analysis indicates that there is not a sharply defined 'best' tunable parameter set, especially when considering only the position estimates over the data arc. The comparison of the EKF estimates for the user spacecraft showed that the filter is capable of high-accuracy results and can easily meet the current accuracy requirements for the spacecraft included in the investigation. The conclusion is that the EKF is a viable option for FDD operational support.
Determining the tube bundle streamlining critical parameters using the numerical experiment method
NASA Astrophysics Data System (ADS)
Kaplunov, S. M.; Val'es, N. G.; Samolysov, A. V.; Marchevskaya, O. A.
2015-08-01
The article is devoted to development and application of mathematical models describing the most dangerous mechanisms through which vibrations are excited in tube bundles and blunt cylindrically shaped structures, and to development of reliable calculation methods for describing these models, which would make it possible to obtain prompt data for designing and subsequent operation of the considered structural elements. For solving such problems, a comprehensive approach is required, which should be based on a combined use of numerical experiments on computers and experimental investigations on full-scale equipment. The authors have developed a procedure for numerically investigating the hydrodynamic forces arising during stalled streamlining and the tube bundle vibrations caused by these forces. The procedure is based on using the developed mathematical model describing fluid-elastic excitation of vibrations in a bundle of elastic tubes placed in external cross flow. The problem of studying fluid-elastic excitation is brought to stability analysis, which is carried out with the assumption about a linear behavior of destabilizing forces for undisturbed state of elastic tubes. A theoretical investigation of the developed mathematical model was carried out, from which the necessary and sufficient condition of system stability has been obtained in terms of system dimensionless parameters (mass, damping, and velocity). An algorithm for numerically determining the matrices of linear hydrodynamic coupling coefficients for particular tube bundles is developed. The validity of the algorithm and the computer programs developed on its basis are checked by comparing the results of test calculations with the bank of known experimental data. A procedure is proposed for determining the matrices of linear hydrodynamic coupling coefficients in bundles having a regular layout of their cross section and a large number of tubes through calculating these matrices for a relatively small
Axial penile rigidity: determinants and relation to hemodynamic parameters.
Goldstein, I; Udelson, D
1998-05-01
Erectile dysfunction may be defined in terms of axial penile rigidity, the physical property that enables the erection to be utilized as a penetration tool during sexual activity. Erectile dysfunction occurs when inadequate axial penile rigidity results in buckling of the penile column when subjected to axial compressive loading situations during vaginal intromission. New multi-disciplinary engineering studies of penile hemodynamic and structural dynamic relationships are reviewed concerning the determinants of axial penile rigidity. Axial penile rigidity develops as a continuum during the increases in intracavernosal pressure and volume changes from the flaccid state and is influenced by intracavernosal pressure, penile tissue mechanical properties and penile geometry. Two penile tissue mechanical properties are especially relevant; cavernosal maximum volume at relatively low intracavernosal pressure, and tunical distensibility, the relative volume of the fully erect to completely flaccid pendulous penis. Two penile geometric properties are critical; the penile aspect ratio, defined as the diameter to length ratio of the pendulous penis, and the magnitude of the flaccid penile diameter. Clinically measured values of axial buckling forces in patients undergoing dynamic pharmacocavernosometry strongly correlated to theoretic-based analytic derived magnitudes of axial penile rigidity based on these above pressure, tissue and geometric determinants. Since axial penile rigidity is not exclusively dependent upon intracavernosal pressure, patients with normal erectile hemodynamics may be erroneously labelled as having psychogenic dysfunction where their true pathophysiology may be related to abnormal penile tissue properties and/or penile geometric factors. Similarly, some patients may claim sufficient rigidity for penetration, but have abnormal hemodynamic erectile function studies. They may have uniquely advantageous tissue mechanical and/or geometric properties. More
Determining hydrodynamic forces in bursting bubbles using DNA nanotube mechanics
Hariadi, Rizal F.; Winfree, Erik; Yurke, Bernard
2015-01-01
Quantifying the mechanical forces produced by fluid flows within the ocean is critical to understanding the ocean’s environmental phenomena. Such forces may have been instrumental in the origin of life by driving a primitive form of self-replication through fragmentation. Among the intense sources of hydrodynamic shear encountered in the ocean are breaking waves and the bursting bubbles produced by such waves. On a microscopic scale, one expects the surface-tension–driven flows produced during bubble rupture to exhibit particularly high velocity gradients due to the small size scales and masses involved. However, little work has examined the strength of shear flow rates in commonly encountered ocean conditions. By using DNA nanotubes as a novel fluid flow sensor, we investigate the elongational rates generated in bursting films within aqueous bubble foams using both laboratory buffer and ocean water. To characterize the elongational rate distribution associated with a bursting bubble, we introduce the concept of a fragmentation volume and measure its form as a function of elongational flow rate. We find that substantial volumes experience surprisingly large flow rates: during the bursting of a bubble having an air volume of 10 mm3, elongational rates at least as large as ϵ˙=1.0×108 s−1 are generated in a fragmentation volume of ∼2×10−6 μL. The determination of the elongational strain rate distribution is essential for assessing how effectively fluid motion within bursting bubbles at the ocean surface can shear microscopic particles and microorganisms, and could have driven the self-replication of a protobiont. PMID:26504222
NASA Astrophysics Data System (ADS)
Garrett, Joseph L.; Somers, David; Munday, Jeremy N.
2015-06-01
Measurements of the Casimir force require the elimination of the electrostatic force between the surfaces. However, due to electrostatic patch potentials, the voltage required to minimize the total force may not be sufficient to completely nullify the electrostatic interaction. Thus, these surface potential variations cause an additional force, which can obscure the Casimir force signal. In this paper, we inspect the spatially varying surface potential of e-beamed, sputtered, sputtered and annealed, and template stripped gold surfaces with Heterodyne amplitude modulated Kelvin probe force microscopy (HAM-KPFM). It is demonstrated that HAM-KPFM improves the spatial resolution of surface potential measurements compared to amplitude modulated Kelvin probe force microscopy. We find that patch potentials vary depending on sample preparation, and that the calculated pressure can be similar to the pressure difference between Casimir force calculations employing the plasma and Drude models.
Determination of the Fracture Parameters in a Stiffened Composite Panel
NASA Technical Reports Server (NTRS)
Lin, Chung-Yi
2000-01-01
A modified J-integral, namely the equivalent domain integral, is derived for a three-dimensional anisotropic cracked solid to evaluate the stress intensity factor along the crack front using the finite element method. Based on the equivalent domain integral method with auxiliary fields, an interaction integral is also derived to extract the second fracture parameter, the T-stress, from the finite element results. The auxiliary fields are the two-dimensional plane strain solutions of monoclinic materials with the plane of symmetry at x(sub 3) = 0 under point loads applied at the crack tip. These solutions are expressed in a compact form based on the Stroh formalism. Both integrals can be implemented into a single numerical procedure to determine the distributions of stress intensity factor and T-stress components, T11, T13, and thus T33, along a three-dimensional crack front. The effects of plate thickness and crack length on the variation of the stress intensity factor and T-stresses through the thickness are investigated in detail for through-thickness center-cracked plates (isotropic and orthotropic) and orthotropic stiffened panels under pure mode-I loading conditions. For all the cases studied, T11 remains negative. For plates with the same dimensions, a larger size of crack yields larger magnitude of the normalized stress intensity factor and normalized T-stresses. The results in orthotropic stiffened panels exhibit an opposite trend in general. As expected, for the thicker panels, the fracture parameters evaluated through the thickness, except the region near the free surfaces, approach two-dimensional plane strain solutions. In summary, the numerical methods presented in this research demonstrate their high computational effectiveness and good numerical accuracy in extracting these fracture parameters from the finite element results in three-dimensional cracked solids.
A novel criterion for determination of material model parameters
NASA Astrophysics Data System (ADS)
Andrade-Campos, A.; de-Carvalho, R.; Valente, R. A. F.
2011-05-01
Parameter identification problems have emerged due to the increasing demanding of precision in the numerical results obtained by Finite Element Method (FEM) software. High result precision can only be obtained with confident input data and robust numerical techniques. The determination of parameters should always be performed confronting numerical and experimental results leading to the minimum difference between them. However, the success of this task is dependent of the specification of the cost/objective function, defined as the difference between the experimental and the numerical results. Recently, various objective functions have been formulated to assess the errors between the experimental and computed data (Lin et al., 2002; Cao and Lin, 2008; among others). The objective functions should be able to efficiently lead the optimisation process. An ideal objective function should have the following properties: (i) all the experimental data points on the curve and all experimental curves should have equal opportunity to be optimised; and (ii) different units and/or the number of curves in each sub-objective should not affect the overall performance of the fitting. These two criteria should be achieved without manually choosing the weighting factors. However, for some non-analytical specific problems, this is very difficult in practice. Null values of experimental or numerical values also turns the task difficult. In this work, a novel objective function for constitutive model parameter identification is presented. It is a generalization of the work of Cao and Lin and it is suitable for all kinds of constitutive models and mechanical tests, including cyclic tests and Baushinger tests with null values.
Evolutionary determination of experimental parameters for ptychographical imaging
Shenfield, Alex; Rodenburg, John M.
2011-06-15
The Ptychographical Iterative Engine (PIE) algorithm is a recently developed novel method of Coherent Diffractive Imaging (CDI) that uses multiple overlapping diffraction patterns to reconstruct an image. This method has successfully produced high quality reconstructions at both optical and X-ray wavelengths but the need for accurate knowledge of the probe positions is currently a limiting factor in the production of high resolution reconstructions at electron wavelengths. This paper examines the shape of the search landscape for producing optimal image reconstructions in the specific case of electron microscopy and then shows how evolutionary search methods can be used to reliably determine experimental parameters in the electron microscopy case (such as the spherical aberration in the probe and the probe positions).
Quantitative Determination of Lineshape Parameters from Velocity Modulation Spectroscopy
NASA Astrophysics Data System (ADS)
Hodges, James N.; McCall, Benjamin J.
2016-06-01
Velocity Modulation Spectroscopy (VMS) has stood as the gold standard in molecular ion spectroscopy for 30 years. Whether in a traditional uni-directional experiment or more complicated cavity-enhanced layouts with additional layers of modulation, VMS remains the preferred ion detection scheme and is responsible for the detection and transition frequency determination of around 50 molecules. Despite its success, VMS still has a great deal of untapped potential. There have only been two other published studies of VMS lineshapes and both struggle with the highly correlated parameters: linewidth, intensity, and velocity modulation amplitude, i.e. the maximum Doppler shift during a period of the discharge. Due to this difficulty, both Gao and Civis made concessions to achieve a good fit. Careful analysis of the contour of the transition profile allows us to properly disentangle those parameters in order to probe the environment of the positive column. We can extract the precise values for the translational temperature of the ion, the relative transition intensity, the ion mobility, and the electric field strength just from the lineshape of a single transition. A firm understanding of the lineshape will facilitate chemical and physical investigations of positive columns and allow for a better understanding of more complicated detection schemes. H. Gao et al., Acta Phys. Sin. 50, 1463 (2001) S. Civis, Chem. Phys. 186, 63 (1994)
Systematic Effects in Earth Orientation Parameters Determined by VLBI
NASA Astrophysics Data System (ADS)
Schuh, H.; Heinkelmann, R.
2015-12-01
Very Long Baseline Interferometry (VLBI) is the only technique that directly connects on the observation level the realizations of ITRS and ICRS in terms of their orientation. Many applications in spacecraft navigation, fundamental astronomy, astrometry and geosciences depend on the Earth Orientation Parameters (EOP) determined by VLBI. Currently, under the IAG/IAU Joint Working Group on the Theory of Earth Rotation, activities are supported to advance the theory of Earth rotation. Some components of Earth Rotation, such as the free modes like the Free Core Nutation (FCN) are not predictable but rely entirely on the observation through VLBI. In our presentation we investigate the EOP when alternating various VLBI analysis options such as correction models, a priori parameters, and other choices with the aim to detect and quantify possible systematic effects. Our approach is purely empirical: we alternate certain analysis options and assess the differences with respect to the reference solution that adheres to the IERS Conventions (2010) and applies the standard parameterization. For demonstration we analyze the regular International VLBI Service for Geodesy and Astrometry (IVS) sessions IVS-R1 and IVS-R4.The IAG flagship component GGOS (Global Geodetic Observing System) aims to provide the EOP with an accuracy of 1 mm on the Earth surface (about 30 microarcseconds). This accuracy target will be applied as a limit to interpret the significance of the differences obtained in our comparisons.
Bicycle ergometer instrumentation to determine muscle and bone forces during exercise
NASA Technical Reports Server (NTRS)
Figueroa, Fernando
1995-01-01
It is hypothesized that bone loss experienced by astronauts in zero gravity conditions may be curtailed by appropriate exercise. According to Wolf's law, bone regenerates when muscles produce stresses by pulling on the bone during daily activity and/or exercise on Earth. to use this theory to prevent or decrease bone loss, one needs to quantify musculoskeletal loads and relate them to bone density changes. In the context of the space program, it is desirable to determine musculoskeletal loads during exercise (using the bicycle ergometer in this case) so that one may make similar measurements on Earth and in space. In this manner, load measurements on Earth may be used as reference to generate similar loads during exercise in space. The work reported in this document entails a musculoskeletal load measurement system that, when complete, will provide forces at muscle insertion points and other contact points, on bone. This data will be used by Dr. Beth A. Todd, who is also a SSF working with Dr. Shackelford, as input to a finite element model of bone sections to determine stress distributions. A bicycle ergometer has been instrumented to measure parameters needed to determine musculoskeletal forces during exercise. A primary feature of the system is its compactness. It uses small/light sensors without line-of-sight requirements. The system developed includes sensors, signal processing, a data acquisition system, and software to collect the data. The sensors used include optical encoders to measure position and orientation of the pedal (foot), accelerometers to determine kinematic parameters of the shank and thigh, load cells to measure pedal forces on the sagittal plane, and EMG probes to measure muscle activity. The signals are processed using anti-aliasing filters and amplifiers. The sensors' output is digitized using 30 channels of a board mounted inside a 486 class PC. A program sets the data acquisition parameters and collects data during a time period specified
Abdel-Wahab, Magd M; Wang, Chong; Vanegas-Useche, Libardo V; Parker, Graham A
2011-06-01
The removal ability of gutter brushes for road sweeping for various debris types and different sweeping parameters is studied through experimental tests. The brushing test rig used comprises two commercial gutter brushes, a concrete test bed, and an asphalt test road with a gutter of 0.25 cm width and 10° slope. The brush-surface contact area is determined by sweeping sand on the concrete test bed. Sweeping problems are identified and discussed, and sweeping criteria for the different debris types are suggested. Also, optimum sweeping parameters are proposed for each debris type. In addition, debris removal mechanisms are discussed and analysed. The results indicate that for large heavy debris such as stones and gravel, it is not difficult to achieve large removal forces, because the steel bristles are relatively stiff. Conversely, high removal forces are not needed for particles of millimetre or micron sizes, but bristle curvature has to be appropriate to remove particles from road concavities. Finally, it is found that mud, especially dry mud on a rough surface, is the hardest debris to sweep, requiring a brush with a large tilt angle and a very large penetration to produce large removal forces.
Chakrapani, Sunil Kishore; Barnard, Daniel J
2017-02-01
The present article investigates the possibility of using nonlinear resonance ultrasound spectroscopy to determine the acoustic nonlinearity parameter (β) and third order elastic constant by developing an inverse problem. A theoretical framework was developed for nonlinear forced vibration of a cantilever beam using material nonlinearity (stress-strain nonlinearity). The resulting nonlinear equation was solved using method of multiple time scales to obtain the nonlinear frequency shifts. The present works focuses only on classical nonlinearity and, therefore, a diverse group of intact, classic nonlinear materials were chosen. The samples were tested using nonlinear resonance ultrasound spectroscopy, and the developed theory was used to invert the experimental frequency shifts to obtain the nonlinearity parameters. The third order elastic constants and β were calculated using their analytical relationship with the nonlinearity parameter. The experimentally determined C111 and β values for all various materials agree well with literature values. In addition to determining β, determination of the sign, or phase of β was also explored theoretically and experimentally.
Determination of the key parameters affecting historic communications satellite trends
NASA Technical Reports Server (NTRS)
Namkoong, D.
1984-01-01
Data representing 13 series of commercial communications satellites procured between 1968 and 1982 were analyzed to determine the factors that have contributed to the general reduction over time of the per circuit cost of communications satellites. The model by which the data were analyzed was derived from a general telecommunications application and modified to be more directly applicable for communications satellites. In this model satellite mass, bandwidth-years, and technological change were the variable parameters. A linear, least squares, multiple regression routine was used to obtain the measure of significance of the model. Correlation was measured by coefficient of determination (R super 2) and t-statistic. The results showed that no correlation could be established with satellite mass. Bandwidth-year however, did show a significant correlation. Technological change in the bandwidth-year case was a significant factor in the model. This analysis and the conclusions derived are based on mature technologies, i.e., satellite designs that are evolutions of earlier designs rather than the first of a new generation. The findings, therefore, are appropriate to future satellites only if they are a continuation of design evolution.
Determination of the key parameters affecting historic communications satellite trends
NASA Astrophysics Data System (ADS)
Namkoong, D.
1984-06-01
Data representing 13 series of commercial communications satellites procured between 1968 and 1982 were analyzed to determine the factors that have contributed to the general reduction over time of the per circuit cost of communications satellites. The model by which the data were analyzed was derived from a general telecommunications application and modified to be more directly applicable for communications satellites. In this model satellite mass, bandwidth-years, and technological change were the variable parameters. A linear, least squares, multiple regression routine was used to obtain the measure of significance of the model. Correlation was measured by coefficient of determination (R super 2) and t-statistic. The results showed that no correlation could be established with satellite mass. Bandwidth-year however, did show a significant correlation. Technological change in the bandwidth-year case was a significant factor in the model. This analysis and the conclusions derived are based on mature technologies, i.e., satellite designs that are evolutions of earlier designs rather than the first of a new generation. The findings, therefore, are appropriate to future satellites only if they are a continuation of design evolution.
Determining CME-driven shock parameters from remote sensing observations
NASA Astrophysics Data System (ADS)
Volpes, L.; Bothmer, V.
2016-02-01
Coronal mass ejections (CMEs) are large scale eruptions of magnetized plasma propagating from the Sun into interplanetary space with speeds varying from a few tens to more than 2500 km s-1. They cause large-scale turbulence in the heliosphere and are the major drivers of space weather. Fast CMEs drive strong shocks in the corona and interplanetary medium and generate plasma turbulence in the post-shock regions ahead of the CME bodies. In this work results from the detailed analysis of a strong CME and shock event on April 3, 2010 are summarized. For this event the solar source region is identified and the CME and shock kinematics are determined from time series of white light images obtained by the SECCHI suite on board the STEREO spacecrafts. The shock's standoff distance, compression ratio and Mach number are derived. A comparison of the derived values with the in-situ measurements shows good agreement. Further comparison of the shock MHD parameters determined from remote sensing observations with in-situ data, including the calculation of power-spectra, will help validating the results and provide new insights into CME generated turbulence. The study will be extended to further events identified in STEREO observations.
Determination of fundamental asteroseismic parameters using the Hilbert transform
NASA Astrophysics Data System (ADS)
Kiefer, René; Schad, Ariane; Herzberg, Wiebke; Roth, Markus
2015-06-01
Context. Solar-like oscillations exhibit a regular pattern of frequencies. This pattern is dominated by the small and large frequency separations between modes. The accurate determination of these parameters is of great interest, because they give information about e.g. the evolutionary state and the mass of a star. Aims: We want to develop a robust method to determine the large and small frequency separations for time series with low signal-to-noise ratio. For this purpose, we analyse a time series of the Sun from the GOLF instrument aboard SOHO and a time series of the star KIC 5184732 from the NASA Kepler satellite by employing a combination of Fourier and Hilbert transform. Methods: We use the analytic signal of filtered stellar oscillation time series to compute the signal envelope. Spectral analysis of the signal envelope then reveals frequency differences of dominant modes in the periodogram of the stellar time series. Results: With the described method the large frequency separation Δν can be extracted from the envelope spectrum even for data of poor signal-to-noise ratio. A modification of the method allows for an overview of the regularities in the periodogram of the time series.
NASA Astrophysics Data System (ADS)
Garber, E. A.; Timofeeva, M. A.
2016-11-01
New propositions are introduced into the technique of energy-force calculation of pinch-pass mills in order to determine the energy-force and technological parameters of skin rolling of cold-rolled steel strips at the minimum errors. The application of these propositions decreases the errors of calculating the forces and torques in a working stand by a factor of 3-5 as compared to the calculation according to the well-known technique, saves the electric power in the existing mills, and demonstrates the possibility of decreasing the dimensions of working stands and the power of the rolling mill engine.
Application of atomic force microscopy on rapid determination of microorganisms for food safety.
Yang, H; Wang, Y
2008-10-01
Rapid detection and quantification of microorganisms is important for food quality, safety, and security. In this field, nanotechnology appears to be promising in its ability to characterize an individual microorganism and detect heterogeneous distribution of microbes in food samples. In this study, atomic force microscopy (AFM), a nanotechnology tool, was used to investigate Escherichia coli (E. coli) qualitatively and quantitatively. E. coli strains B and K12 were used as surrogates to represent pathogenic strains, such as E. coli O157: H7. The results from AFM were compared with those from scanning/transmission electron microscopy (SEM/TEM). The qualitative determination was obtained using morphology and characteristic parameters from AFM images, and the quantitative determination was obtained by calculating the microorganisms in AFM images. The results show that AFM provides a new approach for rapid determination of microorganisms for food safety.
Determining the Pollution Parameters of Degirmendere Stream (Trabzon, NE TURKEY)
NASA Astrophysics Data System (ADS)
Sunnetci, M. O.; Hatipoglu, E.; Firat Ersoy, A.; Gultekin, F.
2013-12-01
The pollution parameters of Degirmendere Stream (Trabzon, TURKEY) are determined in this study. The study area is located between Maçka, 26 km to the south of Trabzon city, and the Black Sea. The area consists of Late Cretaceous volcano-sedimentary rocks, dacite, and basalt, overlain by Eocene volcanic rocks. Quaternary alluvium overlay all geological units following Degirmendere Stream bed. In-situ physical parameter measurements, anion-cation analysis, and heavy and pollutant element analysis on water samples were carried out for four months at four different locations on the stream. The stream's water temperature values were between 4.7 and 9.7oC, pH values were between 6.01 and 7.98, dissolved oxygen (DO) values were between 7.03 and 12.38 mg/l, electrical conductivity (EC) values were between 86 and 254 μS/cm. According to the Piper diagram, the stream water is classified as Ca-HCO3 type water. In the Schoeller diagram, the lines combining mek/l values of the ions in stream water are parallel. Al concentration in the stream water varied from 0.06 to 0.22 mg/l, Mn concentration varied from 0.1 to 0.36 mg/l, and Fe concentration varied from 0.01 to 0.12 mg/l. The stream water is classified as first class in point of temperature, pH, DO, total dissolved solids (TDS), NO3-, P, Pb, Fe, and Al; first and second class in point of NH4+; second class in point of Cu; and third class in point of NO2-, according to the Water Pollution Control Regulation of the Turkish Republic's Criteria for Inland Surface Water Classification. Results indicate waters of the Degirmendere Stream is very good-good for irrigation use according to the Wilcox diagram.
Determining extreme parameter correlation in ground water models.
Hill, M.C.; Osterby, O.
2003-01-01
In ground water flow system models with hydraulic-head observations but without significant imposed or observed flows, extreme parameter correlation generally exists. As a result, hydraulic conductivity and recharge parameters cannot be uniquely estimated. In complicated problems, such correlation can go undetected even by experienced modelers. Extreme parameter correlation can be detected using parameter correlation coefficients, but their utility depends on the presence of sufficient, but not excessive, numerical imprecision of the sensitivities, such as round-off error. This work investigates the information that can be obtained from parameter correlation coefficients in the presence of different levels of numerical imprecision, and compares it to the information provided by an alternative method called the singular value decomposition (SVD). Results suggest that (1) calculated correlation coefficients with absolute values that round to 1.00 were good indicators of extreme parameter correlation, but smaller values were not necessarily good indicators of lack of correlation and resulting unique parameter estimates; (2) the SVD may be more difficult to interpret than parameter correlation coefficients, but it required sensitivities that were one to two significant digits less accurate than those that required using parameter correlation coefficients; and (3) both the SVD and parameter correlation coefficients identified extremely correlated parameters better when the parameters were more equally sensitive. When the statistical measures fail, parameter correlation can be identified only by the tedious process of executing regression using different sets of starting values, or, in some circumstances, through graphs of the objective function.
NASA Technical Reports Server (NTRS)
Suit, William T.
1989-01-01
Estimates of longitudinal stability and control parameters for the space shuttle were determined by applying a maximum likelihood parameter estimation technique to Challenger flight test data. The parameters for pitching moment coefficient, C(m sub alpha), (at different angles of attack), pitching moment coefficient, C(m sub delta e), (at different elevator deflections) and the normal force coefficient, C(z sub alpha), (at different angles of attack) describe 90 percent of the response to longitudinal inputs during Space Shuttle Challenger flights with C(m sub delta e) being the dominant parameter. The values of C(z sub alpha) were found to be input dependent for these tests. However, when C(z sub alpha) was set at preflight predictions, the values determined for C(m sub delta e) changed less than 10 percent from the values obtained when C(z sub alpha) was estimated as well. The preflight predictions for C(z sub alpha) and C(m sub alpha) are acceptable values, while the values of C(z sub delta e) should be about 30 percent less negative than the preflight predictions near Mach 1, and 10 percent less negative, otherwise.
Analyzing a hydrocarbon reservoir by determining the response of that reservoir to tidal forces
Graebner, P.
1991-08-20
This patent describes a method for determining a component of the response of a hydrocarbons reservoir to tidal forces. It comprises measuring a variable responsive to tidal forces within the reservoir over a measurement time period; determining a theoretical earth-tide for the reservoir over the measurement time period; and determining the component of the response to tidal forces by comparing the variable measurements and the theoretical earth-tide determinations.
Parameter estimation of social forces in pedestrian dynamics models via a probabilistic method.
Corbetta, Alessandro; Muntean, Adrian; Vafayi, Kiamars
2015-04-01
Focusing on a specific crowd dynamics situation, including real life experiments and measurements, our paper targets a twofold aim: (1) we present a Bayesian probabilistic method to estimate the value and the uncertainty (in the form of a probability density function) of parameters in crowd dynamic models from the experimental data; and (2) we introduce a fitness measure for the models to classify a couple of model structures (forces) according to their fitness to the experimental data, preparing the stage for a more general model-selection and validation strategy inspired by probabilistic data analysis. Finally, we review the essential aspects of our experimental setup and measurement technique.
Density profiles of supernova matter and determination of neutrino parameters
Chiu, S.-H.
2007-08-15
The flavor conversion of supernova neutrinos can lead to observable signatures related to the unknown neutrino parameters. As one of the determinants in dictating the efficiency of resonant flavor conversion, the local density profile near the Mikheyev-Smirnov-Wolfenstein (MSW) resonance in a supernova environment is, however, not so well understood. In this analysis, variable power-law functions are adopted to represent the independent local density profiles near the locations of resonance. It is shown that the uncertain matter density profile in a supernova, the possible neutrino mass hierarchies, and the undetermined 1-3 mixing angle would result in six distinct scenarios in terms of the survival probabilities of {nu}{sub e} and {nu}{sub e}. The feasibility of probing the undetermined neutrino mass hierarchy and the 1-3 mixing angle with the supernova neutrinos is then examined using several proposed experimental observables. Given the incomplete knowledge of the supernova matter profile, the analysis is further expanded to incorporate the Earth matter effect. The possible impact due to the choice of models, which differ in the average energy and in the luminosity of neutrinos, is also addressed in the analysis.
Siebert, T; Sust, M; Thaller, S; Tilp, M; Wagner, H
2007-04-01
We evaluate an improved method for individually determining neuromuscular properties in vivo. The method is based on Hill's equation used as a force law combined with Newton's equation of motion. To ensure the range of validity of Hill's equation, we first perform detailed investigations on in vitro single muscles. The force-velocity relation determined with the model coincides well with results obtained by standard methods (r=.99) above 20% of the isometric force. In addition, the model-predicted force curves during work loop contractions very well agree with measurements (mean difference: 2-3%). Subsequently, we deduce theoretically under which conditions it is possible to combine several muscles of the human body to model muscles. This leads to a model equation for human leg extension movements containing parameters for the muscle properties and for the activation. To numerically determine these invariant neuromuscular properties we devise an experimental method based on concentric and isometric leg extensions. With this method we determine individual muscle parameters from experiments such that the simulated curves agree well with experiments (r=.99). A reliability test with 12 participants revealed correlations r=.72-.91 for the neuromuscular parameters (p<.01). Predictions of similar movements under different conditions show mean errors of about 5%. In addition, we present applications in sports practise and theory.
NASA Astrophysics Data System (ADS)
Chu, Zhongyi; Ma, Ye; Hou, Yueyang; Wang, Fengwen
2017-02-01
This paper presents a novel identification method for the intact inertial parameters of an unknown object in space captured by a manipulator in a space robotic system. With strong dynamic and kinematic coupling existing in the robotic system, the inertial parameter identification of the unknown object is essential for the ideal control strategy based on changes in the attitude and trajectory of the space robot via capturing operations. Conventional studies merely refer to the principle and theory of identification, and an error analysis process of identification is deficient for a practical scenario. To solve this issue, an analysis of the effect of errors on identification is illustrated first, and the accumulation of measurement or estimation errors causing poor identification precision is demonstrated. Meanwhile, a modified identification equation incorporating the contact force, as well as the force/torque of the end-effector, is proposed to weaken the accumulation of errors and improve the identification accuracy. Furthermore, considering a severe disturbance condition caused by various measured noises, the hybrid immune algorithm, Recursive Least Squares and Affine Projection Sign Algorithm (RLS-APSA), is employed to decode the modified identification equation to ensure a stable identification property. Finally, to verify the validity of the proposed identification method, the co-simulation of ADAMS-MATLAB is implemented by multi-degree of freedom models of a space robotic system, and the numerical results show a precise and stable identification performance, which is able to guarantee the execution of aerospace operations and prevent failed control strategies.
Determining important parameters related to cyanobacterial alkaloid toxin exposure
Love, A H
2005-09-16
Science-based decision making required robust and high-fidelity mechanistic data about the system dynamics and impacts of system changes. Alkaloid cyanotoxins have the characteristics to warrant consideration for their potential threat. Since insufficient information is available to construct a systems model for the alkaloid cyanotoxins, saxitoxins, anatoxins, and anatoxin-a(S), an accurate assessments of these toxins as a potential threat for use for intentional contamination is not possible. Alkaloid cyanotoxin research that contributed to such a model has numerous areas of overlap for natural and intentional health effects issues that generates dual improvements to the state of the science. The use of sensitivity analyses of systems models can identify parameters that, when determined, result in the greatest impact to the overall system and may help to direct the most efficient use of research funding. This type of modeling-assisted experimentation may allow rapid progress for overall system understanding compared to observational or disciplinary research agendas. Assessment and management of risk from intentional contamination can be performed with greater confidence when mechanisms are known and the relationships between different components are validated. This level of understanding allows high-fidelity assessments that do not hamper legitimate possession of these toxins for research purposes, while preventing intentional contamination that would affect public health. It also allows for appropriate response to an intentional contamination event, even if the specific contamination had not been previous considered. Development of science-based decision making tools will only improve our ability to address the new requirements addressing potential threats to our nation.
Multifactorial determination of the electric drive for the force compensating manipulator
NASA Astrophysics Data System (ADS)
Pyatibratov, G. Ya; Danshina, A. A.
2017-02-01
The methodology of multifactorial determination of rational parameters of transmission gear and synchronous electric motor driving by permanent magnets for the system of the vertical freight movement of the force compensating manipulator is offered. An integrated approach to the selection of the power part of this manipulator takes into account: motor speed matching and an executive mechanism of the manipulator, operation of the electric drive with a minimum possible value of the maximum torque at the movement of freight with constant speed and with acceleration at different values of the freight mass. A reasonable radius of mechanism activation is determined from accepted values with application of the compromise approach enabling to consider at the same time the performance of all limiting conditions. The electromechanical module of the manipulator is selected when a value of the activation radius provides the minimum possible required motor torque.
NASA Technical Reports Server (NTRS)
Sutton, M. A.; Davis, P. K.
1976-01-01
Numerical solutions of the governing equations of motion of a liquid squeeze film damped forced vibration system were carried out to examine the feasibility of using a liquid squeeze film to cushion and protect large structures, such as buildings, located in areas of high seismic activity. The mathematical model used was that for a single degree of freedom squeeze film damped spring mass system. The input disturbance was simulated by curve fitting actual seismic data with an eleventh order Lagranging polynomial technique. Only the normal component of the seismic input was considered. The nonlinear, nonhomogeneous governing differential equation of motion was solved numerically to determine the transmissibility over a wide range of physical parameters using a fourth-order Runge-Kutta technique. It is determined that a liquid squeeze film used as a damping agent in a spring-mass system can significantly reduce the response amplitude for a seismic input disturbance.
Determination of parameters of a nuclear reactor through noise measurements
Cohn, C.E.
1975-07-15
A method of measuring parameters of a nuclear reactor by noise measurements is described. Noise signals are developed by the detectors placed in the reactor core. The polarity coincidence between the noise signals is used to develop quantities from which various parameters of the reactor can be calculated. (auth)
Adhesion Forces between Lewis(X) Determinant Antigens as Measured by Atomic Force Microscopy.
Tromas, C; Rojo, J; de la Fuente, J M; Barrientos, A G; García, R; Penadés, S
2001-01-01
The adhesion forces between individual molecules of Lewis(X) trisaccharide antigen (Le(X) ) have been measured in water and in calcium solution by using atomic force microscopy (AFM, see graph). These results demonstrate the self-recognition capability of this antigen, and reinforce the hypothesis that carbohydrate-carbohydrate interaction could be considered as the first step in the cell-adhesion process in nature.
Determination of Radiative Forcing of Saharan Dust using Combined TOMS and ERBE Data
NASA Technical Reports Server (NTRS)
Hsu, N. Christina; Herman, Jay R.; Weaver, Clark
1999-01-01
The direct radiative forcing of Saharan dust aerosols has been determined by combining aerosol information derived from Nimbus-7 TOMS with radiation measurements observed at the top of atmosphere (TOA) by NOAA-9 ERBE made during February-July 1985. Cloud parameters and precipitable water derived from the NOAA-9 HIRS2 instrument were used to aid in screening for clouds and water vapor in the analyses. Our results indicate that under "cloud-free" and "dry" conditions there is a good correlation between the ERBE TOA outgoing longwave fluxes and the TOMS aerosol index measurements over both land and ocean in areas under the influence of airborne Saharan dust. The ERBE TOA outgoing shortwave fluxes were also found to correlate well with the dust loading derived from TOMS over ocean. However, the calculated shortwave forcing of Saharan dust aerosols is very weak and noisy over land for the range of solar zenith angle viewed by the NOAA-9 ERBE in 1985. Sensitivity factors of the TOA outgoing fluxes to changes in aerosol index were estimated using a linear regression fit to the ERBE and TOMS measurements. The ratio of the shortwave-to-longwave response to changes in dust loading over the ocean is found to be roughly 2 to 3, but opposite in sign. The monthly averaged "clear-sky" TOA direct forcing of airborne Saharan dust was also calculated by multiplying these sensitivity factors by the TOMS monthly averaged "clear-sky" aerosol index. Both the observational and theoretical analyses indicate that the dust layer height, ambient moisture content as well as the presence of cloud all play an important role in determining the TOA direct radiative forcing due to mineral aerosols.
Li, Xinbi; Ponomarev, Sergei Y; Sa, Qina; Sigalovsky, Daniel L; Kaminski, George A
2013-05-30
A previously introduced polarizable simulations with second-order interaction model (POSSIM) force field has been extended to include parameters for small molecules serving as models for peptide and protein side-chains. Parameters have been fitted to permit reproducing many-body energies, gas-phase dimerization energies, and geometries and liquid-phase heats of vaporization and densities. Quantum mechanical and experimental data have been used as the target for the fitting. The POSSIM framework combines accuracy of a polarizable force field and computational efficiency of the second-order approximation of the full-scale induced point dipole polarization formalism. The resulting parameters can be used for simulations of the parameterized molecules themselves or their analogues. In addition to this, these force field parameters are currently being used in further development of the POSSIM fast polarizable force field for proteins.
Li, Xinbi; Ponomarev, Sergei Y.; Sa, Qina; Sigalovsky, Daniel L.; Kaminski, George A.
2013-01-01
A previously introduced POSSIM (POlarizable Simulations with Second order Interaction Model) force field has been extended to include parameters for small molecules serving as models for peptide and protein side-chains. Parameters have been fitted to permit reproducing many-body energies, gas-phase dimerization energies and geometries and liquid-phase heats of vaporization and densities. Quantum mechanical and experimental data have been used as the target for the fitting. The POSSIM framework combines accuracy of a polarizable force field and computational efficiency of the second-order approximation of the full-scale induced point dipole polarization formalism. The resulting parameters can be used for simulations of the parameterized molecules themselves or their analogues. In addition to this, these force field parameters are currently being employed in further development of the POSSIM fast polarizable force field for proteins. PMID:23420678
NASA Astrophysics Data System (ADS)
Abdel-Jaber, H.; Glisic, B.
2014-07-01
Structural health monitoring (SHM) consists of the continuous or periodic measurement of structural parameters and their analysis with the aim of deducing information about the performance and health condition of a structure. The significant increase in the construction of prestressed concrete bridges motivated this research on an SHM method for the on-site determination of the distribution of prestressing forces along prestressed concrete beam structures. The estimation of the distribution of forces is important as it can give information regarding the overall performance and structural integrity of the bridge. An inadequate transfer of the designed prestressing forces to the concrete cross-section can lead to a reduced capacity of the bridge and consequently malfunction or failure at lower loads than predicted by design. This paper researches a universal method for the determination of the distribution of prestressing forces along concrete beam structures at the time of transfer of the prestressing force (e.g., at the time of prestressing or post-tensioning). The method is based on the use of long-gauge fiber optic sensors, and the sensor network is similar (practically identical) to the one used for damage identification. The method encompasses the determination of prestressing forces at both healthy and cracked cross-sections, and for the latter it can yield information about the condition of the cracks. The method is validated on-site by comparison to design forces through the application to two structures: (1) a deck-stiffened arch and (2) a curved continuous girder. The uncertainty in the determination of prestressing forces was calculated and the comparison with the design forces has shown very good agreement in most of the structures’ cross-sections, but also helped identify some unusual behaviors. The method and its validation are presented in this paper.
DeSmitt, Holly J; Domire, Zachary J
2016-12-01
Biomechanical models are sensitive to the choice of model parameters. Therefore, determination of accurate subject specific model parameters is important. One approach to generate these parameters is to optimize the values such that the model output will match experimentally measured strength curves. This approach is attractive as it is inexpensive and should provide an excellent match to experimentally measured strength. However, given the problem of muscle redundancy, it is not clear that this approach generates accurate individual muscle forces. The purpose of this investigation is to evaluate this approach using simulated data to enable a direct comparison. It is hypothesized that the optimization approach will be able to recreate accurate muscle model parameters when information from measurable parameters is given. A model of isometric knee extension was developed to simulate a strength curve across a range of knee angles. In order to realistically recreate experimentally measured strength, random noise was added to the modeled strength. Parameters were solved for using a genetic search algorithm. When noise was added to the measurements the strength curve was reasonably recreated. However, the individual muscle model parameters and force curves were far less accurate. Based upon this examination, it is clear that very different sets of model parameters can recreate similar strength curves. Therefore, experimental variation in strength measurements has a significant influence on the results. Given the difficulty in accurately recreating individual muscle parameters, it may be more appropriate to perform simulations with lumped actuators representing similar muscles.
Probe-rotating atomic force microscopy for determining material properties
Lee, Sang Heon
2014-03-15
In this paper, we propose a probe-rotating atomic force microscope that enables scan in an arbitrary direction in the contact imaging mode, which is difficult to achieve using a conventional atomic force microscope owing to the orientation-dependent probe and the inability to rotate the probe head. To enable rotation of the probe about its vertical axis, we employed a compact and light probe head, the sensor of which is made of an optical disk drive pickup unit. Our proposed mechanical configuration, operating principle, and control system enables axial and lateral scan in various directions.
40 CFR 86.229-94 - Road load force, test weight, and inertia weight class determination.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Road load force, test weight, and... § 86.229-94 Road load force, test weight, and inertia weight class determination. (a) Flywheels, electrical forces, or other means of simulating test weight as shown in the table in this paragraph shall...
40 CFR 86.229-94 - Road load force, test weight, and inertia weight class determination.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Road load force, test weight, and... § 86.229-94 Road load force, test weight, and inertia weight class determination. (a) Flywheels, electrical forces, or other means of simulating test weight as shown in the table in this paragraph shall...
Oh, Suk Yung; Bae, Young Chan
2010-07-15
The method presented in this paper was developed to predict liquid-liquid equilibria in ternary liquid mixtures by using a combination of a thermodynamic model and molecular dynamics simulations. In general, common classical thermodynamic models have many parameters which are determined by fitting a model with experimental data. This proposed method, however, provides a simple procedure for calculating liquid-liquid equilibria utilizing binary interaction parameters and molecular size parameters determined from molecular dynamics simulations. This method was applied to mixtures containing water, hydrocarbons, alcohols, chlorides, ketones, acids, and other organic liquids over various temperature ranges. The predicted results agree well with the experimental data without the use of adjustable parameters.
Determinants of contractile forces generated in disorganized actomyosin bundles.
Kim, Taeyoon
2015-04-01
Actomyosin machinery is a fundamental engine consisting mostly of actin filaments, molecular motors, and passive cross-linkers, generating mechanical forces required for biological processes of non-muscle cells such as cell migration, cytokinesis, and morphogenesis. Although the molecular and physical properties of key elements in the actomyosin machinery have been characterized well, it still remains unclear how macroscopic force buildup and dissipation in actomyosin networks and bundles depend on the microscopic properties of individual cytoskeletal components and their local interactions. To bridge such a gap between macroscopic and microscopic scales, we have developed a three-dimensional computational model of actomyosin bundles clamped to an elastic substrate with minimal components: actin filaments, passive cross-linkers, and active motors. Our model accounts for several key features neglected by previous studies despite their significance for force generation, such as realistic structure and kinetics of the motors. Using the model, we systematically investigated how net tension in actomyosin bundles is governed via interplay between motors and cross-linkers. We demonstrated motors can generate large tension on a bundle in the absence of cross-linkers in a very inefficient, unstable manner. Cross-linkers help motors to generate their maximum potential forces as well as enhance overall connectivity, leading to much higher efficiency and stability. We showed further that the cross-linkers behave as a molecular clutch with tunable friction which has quite distinct effects on net tension depending on their cross-linking angles. We also examined the source of symmetry breaking between tensile and compressive forces during tension generation process and discussed how the length and dynamics of actin filaments and the stiffness of the elastic substrate can affect the generated tension.
NASA Astrophysics Data System (ADS)
Gusev, Ye. M.; Nasonova, O. N.; Dzhogan, L. Ya.
2009-04-01
Construction of a model for simulating hydrological processes, to our opinion, should be based on mathematical description of the real physical heat and water exchange processes occurring in a soil - vegetation/snow cover - atmosphere system rather than on available data. This allows one to create more universal model, which can be applied at different temporal and spatial scales and under different natural conditions. More than that, such a model can be applied for poorly-gauged basins and in the presence of uncertain/unreliable forcing data and land surface parameters, provided that reliable runoff measurements are available at least for several years. The latter is necessary for model calibration to reduce the impact of uncertainties in input data on model results. The present work is intended to confirm the above statements using the land surface model SWAP (Soil Water - Atmosphere - Plants). SWAP is a physically-based model describing the processes of heat and water exchange within a soil-vegetation/snow cover-atmosphere system (SVAS). The model can be applied both for point (or grid cell) simulations of vertical fluxes and state variables of SVAS in atmospheric science applications, and for simulating streamflow on different scales — from small catchments to continental scale river basins. The results of model validations have demonstrated that SWAP is able to reproduce (without calibration) heat and water exchange processes (in particular, hydrological processes) adequately, provided that input data of high quality are available. In poorly-gauged basins, alternative sources of information should be used. Here, the global data sets on forcing data and land surface parameters were used for simulating streamflow from two pan-Arctic river basins (the Mezen and the Pechora basins with an area of 78 000 and 324 000 sq.km, respectively), located in the northeast part of the European Russia. The Mezen and the Pechora basins were represented for modeling purposes
Dehzangi, Arash; Larki, Farhad; Hutagalung, Sabar D.; Goodarz Naseri, Mahmood; Majlis, Burhanuddin Y.; Navasery, Manizheh; Hamid, Norihan Abdul; Noor, Mimiwaty Mohd
2013-01-01
In this letter, we investigate the fabrication of Silicon nanostructure patterned on lightly doped (1015 cm−3) p-type silicon-on-insulator by atomic force microscope nanolithography technique. The local anodic oxidation followed by two wet etching steps, potassium hydroxide etching for silicon removal and hydrofluoric etching for oxide removal, are implemented to reach the structures. The impact of contributing parameters in oxidation such as tip materials, applying voltage on the tip, relative humidity and exposure time are studied. The effect of the etchant concentration (10% to 30% wt) of potassium hydroxide and its mixture with isopropyl alcohol (10%vol. IPA ) at different temperatures on silicon surface are expressed. For different KOH concentrations, the effect of etching with the IPA admixture and the effect of the immersing time in the etching process on the structure are investigated. The etching processes are accurately optimized by 30%wt. KOH +10%vol. IPA in appropriate time, temperature, and humidity. PMID:23776479
[Study on Indicator Densitometry Determination Method of Hemodynamic Parameters].
Liu, Guang-da; Zhou, Run-dong; Zha, Yu-tong; Cai, Jing; Niu, Jun-qi; Gao, Pu-jun; Liu, Li-li
2016-03-01
Measurement for hemodynamic parameters has always been a hot spot of clinical research. Methods for measuring hemodynamic parameters clinically have the problems of invasiveness, complex operation and being unfit for repeated measurement. To solve the problems, an indicator densitometry analysis method is presented based on near-infrared spectroscopy (NIRS) and indicator dilution theory, which realizes the hemodynamic parameters measured noninvasively. While the indocyanine green (ICG) was injected into human body, circulation carried the indicator mixing and diluting with the bloodstream. Then the near-nfrared probe was used to emit near-infrared light at 735, 805 and 940 nm wavelengths through the sufferer's fingertip and synchronously capture the transmission light containing the information of arterial pulse wave. By uploading the measured data, the computer would calculate the ICG concentration, establish continuous concentration curve and compute some intermediate variables such as the mean transmission time (MTT) and the initial blood ICG concentration (c(t0)). Accordingly Cardiac Output (CO) and Circulating Blood Volume (CBV) could be calculated. Compared with the clinical "gold standard" methods of thermodilution and I-131 isotope-labelling method to measure the two parameters by clinical controlled trials, ten sets of data were obtained. The maximum relative errors of this method were 8.88% and 4.28% respectively, and both of the average relative errors were below 5%. The result indicates that this method can meet the clinical accuracy requirement and can be used as a noninvasive, repeatable and applied solution for clinical hemodynamnic parameters measurement.
The Determinants of Career Decisions of Air Force Pilots.
1981-05-01
entry into the Air Force, 2) age at the beginning of the sample period, 3) source of commission, 4) ethnic background, and 5) state from which accessed...Changing attitudes and characteristics of the officer a population would lead one to expect different responses to the same environment in different time...possible to analyse a larger segment of the pilot population . There are other year groups, both earlier and later than the ones used here, that were
Zgarbová, Marie; Luque, F. Javier; Šponer, Jiří; Cheatham, Thomas E.; Otyepka, Michal; Jurečka, Petr
2013-01-01
We present a refinement of the backbone torsion parameters ε and ζ of the Cornell et al. AMBER force field for DNA simulations. The new parameters, denoted as εζOL1, were derived from quantum-mechanical calculations with inclusion of conformation-dependent solvation effects according to the recently reported methodology (J. Chem. Theory Comput. 2012, 7(9), 2886-2902). The performance of the refined parameters was analyzed by means of extended molecular dynamics (MD) simulations for several representative systems. The results showed that the εζOL1 refinement improves the backbone description of B-DNA double helices and G-DNA stem. In B-DNA simulations, we observed an average increase of the helical twist and narrowing of the major groove, thus achieving better agreement with X-ray and solution NMR data. The balance between populations of BI and BII backbone substates was shifted towards the BII state, in better agreement with ensemble-refined solution experimental results. Furthermore, the refined parameters decreased the backbone RMS deviations in B-DNA MD simulations. In the antiparallel guanine quadruplex (G-DNA) the εζOL1 modification improved the description of non-canonical α/γ backbone substates, which were shown to be coupled to the ε/ζ torsion potential. Thus, the refinement is suggested as a possible alternative to the current ε/ζ torsion potential, which may enable more accurate modeling of nucleic acids. However, long-term testing is recommended before its routine application in DNA simulations. PMID:24058302
Hansen, Clint; Venture, Gentiane; Rezzoug, Nasser; Gorce, Philippe; Isableu, Brice
2014-05-07
Over the last decades a variety of research has been conducted with the goal to improve the Body Segment Inertial Parameters (BSIP) estimations but to our knowledge a real validation has never been completely successful, because no ground truth is available. The aim of this paper is to propose a validation method for a BSIP identification method (IM) and to confirm the results by comparing them with recalculated contact forces using inverse dynamics to those obtained by a force plate. Furthermore, the results are compared with the recently proposed estimation method by Dumas et al. (2007). Additionally, the results are cross validated with a high velocity overarm throwing movement. Throughout conditions higher correlations, smaller metrics and smaller RMSE can be found for the proposed BSIP estimation (IM) which shows its advantage compared to recently proposed methods as of Dumas et al. (2007). The purpose of the paper is to validate an already proposed method and to show that this method can be of significant advantage compared to conventional methods.
Determining frequentist confidence limits using a directed parameter space search
Daniel, Scott F.; Connolly, Andrew J.; Schneider, Jeff
2014-10-10
We consider the problem of inferring constraints on a high-dimensional parameter space with a computationally expensive likelihood function. We propose a machine learning algorithm that maps out the Frequentist confidence limit on parameter space by intelligently targeting likelihood evaluations so as to quickly and accurately characterize the likelihood surface in both low- and high-likelihood regions. We compare our algorithm to Bayesian credible limits derived by the well-tested Markov Chain Monte Carlo (MCMC) algorithm using both multi-modal toy likelihood functions and the seven yr Wilkinson Microwave Anisotropy Probe cosmic microwave background likelihood function. We find that our algorithm correctly identifies the location, general size, and general shape of high-likelihood regions in parameter space while being more robust against multi-modality than MCMC.
ERIC Educational Resources Information Center
Gamble, Reed
1989-01-01
Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)
NASA Astrophysics Data System (ADS)
Vulc, Silvia
2014-12-01
This paper presents a study on grinding tungsten carbide DK460UF, through experimental investigation using diamond grinding wheel with 54 μm grain size. Different sets of experiments were performed to study the effects of the independent grinding parameters such as grinding wheel speed, feed and depth of cut on cutting forces. Test results showed that the feed and depth of cut influence significantly the cutting forces. The research was lead to optimize the process parameters for reducing cutting forces. In this way, for different parameters of cutting regime, it were measured the values of the components of the grinding force, tangential component, Ft and normal component Fn. The results of the experiment showed that it is better to use great speeds and small feed rate and depth of cut in grinding tungsten carbides, such as DK460UF
Determining the Kinetic Parameters Characteristic of Microalgal Growth.
ERIC Educational Resources Information Center
Martinez Sancho, Maria Eugenie; And Others
1991-01-01
An activity in which students obtain a growth curve for algae, identify the exponential and linear growth phases, and calculate the parameters which characterize both phases is described. The procedure, a list of required materials, experimental conditions, analytical technique, and a discussion of the interpretations of individual results are…
Development of a subsidence database and determination of subsidence parameters
Peng, S.S.; Luo, Y.; Zhang, Z.M.
1995-11-01
A total of 209 cases of subsidence data over longwall panels in 16 US coal seams have been collected and built into a subsidence database. The database is developed under MS Windows environment. It uses a very user-friendly menu driven system. The empirical formulae for a number of commonly used subsidence parameters have been derived from those collected subsidence data.
Liu, Y; Weinert, M; Li, L
2015-01-21
Graphene vacancies are engineered for novel functionalities, however, the charge state of these defects, the key parameter that is vital to charge transfer during chemical reactions and carrier scattering, is generally unknown. Here, we carried out atomic resolution imaging of graphene vacancy defects created by Ar plasma using noncontact atomic force microscopy, and made the first determination of their charge state by local contact potential difference measurements. Combined with density functional theory calculations, we show that graphene vacancies are typically positively charged, with size-dependent charge states that are not necessarily integer-valued. These findings provide new insights into carrier scattering by vacancy defects in graphene, as well as its functionalization for chemical sensing and catalysis, and underline the tunability of these functions by controlling the size of vacancy defect.
Comparison of Methods to Obtain Force-Field Parameters for Metal Sites.
Hu, LiHong; Ryde, Ulf
2011-08-09
We have critically examined and compared various ways to obtain standard harmonic molecular mechanics (MM) force-field parameters for metal sites in proteins, using the 12 most common Zn(2+) sites as test cases. We show that the parametrization of metal sites is hard to treat with automatic methods. The choice of method is a compromise between speed and accuracy and therefore depends on the intended use of the parameters. If the metal site is not of central interest in the investigation, for example, a structural metal far from the active site, a simple and fast parametrization is normally enough, using either a nonbonded model with restraints or a bonded parametrization based on the method of Seminario. On the other hand, if the metal site is of central interest in the investigation, a more accurate method is needed to give quantitative results, for example, the method by Norrby and Liljefors. The former methods are semiautomatic and can be performed in seconds, once a quantum mechanical (QM) geometry optimization and frequency calculation has been performed, whereas the latter method typically takes several days and requires significant human intervention. All approaches require a careful selection of the atom types used. For a nonbonded model, standard atom types can be used, whereas for a bonded model, it is normally wise to use special atom types for each metal ligand. For accurate results, new atom types for all atoms in the metal site can be used. Atomic charges should also be considered. Typically, QM restrained electrostatic potential charges are accurate and easy to obtain once the QM calculation is performed, and they allow for charge transfer within the complex. For negatively charged complexes, it should be checked that hydrogen atoms of the ligands get proper charges. Finally, water ligands pose severe problems for bonded models in force fields that ignore nonbonded interactions for atoms separated by two bonds. Complexes with a single water ligand
NASA Astrophysics Data System (ADS)
de Sousa, Kleverson C.; Domingues, Allan C.; Pereira, Pedro P. de S.; Carneiro, Sergio H.; de Morais, Marcus V. G.; Fabro, Adriano T.
2016-06-01
The experimental determination of modal parameters, i.e. natural frequencies, mode shapes and damping ratio, are key in characterizing the dynamic behaviour of structures. Typically, such parameters are obtained from dynamic measurements using one or a set of accelerometers, for response measurements, along with force transducers from an impact hammer or an electrodynamic actuator, i.e. a shaker. However, lightweight structures, commonly applied in the aerospace industry, can be significantly affected by the added mass from accelerometers. Therefore, non-contact measurement techniques, like Laser Doppler Vibrometer (LDV), are a more suitable approach in determining the dynamic characteristics of such structures. In this article, the procedures and results of a modal test for a honeycomb sandwich panel for aerospace applications are presented and discussed. The main objectives of the test are the identification of natural frequencies and mode shapes in order to validate a numerical model, as well as the identification of the damping characteristics of the panel. A validated numerical model will be necessary for future detailed response analysis of the satellite, including vibroacoustic investigations to account for acoustic excitations encountered during launching. The numerical model using homogenised material properties is updated to fit the experimental results and very good agreement between experimental and numerically obtained natural frequencies and mode shapes.
Blümel, Marcus; Guschlbauer, Christoph; Daun-Gruhn, Silvia; Hooper, Scott L; Büschges, Ansgar
2012-11-01
Models built using mean data can represent only a very small percentage, or none, of the population being modeled, and produce different activity than any member of it. Overcoming this "averaging" pitfall requires measuring, in single individuals in single experiments, all of the system's defining characteristics. We have developed protocols that allow all the parameters in the curves used in typical Hill-type models (passive and active force-length, series elasticity, force-activation, force-velocity) to be determined from experiments on individual stick insect muscles (Blümel et al. 2012a). A requirement for means to not well represent the population is that the population shows large variation in its defining characteristics. We therefore used these protocols to measure extensor muscle defining parameters in multiple animals. Across-animal variability in these parameters can be very large, ranging from 1.3- to 17-fold. This large variation is consistent with earlier data in which extensor muscle responses to identical motor neuron driving showed large animal-to-animal variability (Hooper et al. 2006), and suggests accurate modeling of extensor muscles requires modeling individual-by-individual. These complete characterizations of individual muscles also allowed us to test for parameter correlations. Two parameter pairs significantly co-varied, suggesting that a simpler model could as well reproduce muscle response.
Possibility of determination of the asymptotic level-density parameter
Kudyaev, G.A.; Ostapenko, Y.B.; Svirin, M.I.; Smirenkin, G.N.
1988-02-01
We investigate the sensitivity of the fissility of nuclei to the parameters of the density of excited levels and conclude that the nuclei in the region of Pb are most favorable for an experimental estimate of the asymptotic parameter a-italic-tilde = ..cap alpha..A. The mean value ..cap alpha.. = 0.086 +- 0.009 MeV/sup -1/ is found from analysis of the fission of seven nuclei from /sup 201/Tl to /sup 213/At. This value is in agreement with the phenomenological description of the energy dependence a(U) (..cap alpha.. = 0.093 MeV/sup -1/) and with the theoretical prediction ..cap alpha.. = 0.09 MeV/sup -1/ obtained for a Woods-Saxon potential.
Direct determination of neutrino mass parameters at future colliders
Kadastik, M.; Raidal, M.; Rebane, L.
2008-06-01
If the observed light neutrino masses are induced by their Yukawa couplings to singlet right-handed neutrinos, the natural smallness of those makes direct collider tests of the electroweak scale neutrino mass mechanisms difficult in the simplest models. In the triplet Higgs seesaw scenario the smallness of light neutrino masses may come from the smallness of B-L breaking parameters, allowing sizable Yukawa couplings even for a TeV scale triplet. We show that, in this scenario, measuring the branching fractions of doubly charged Higgs to different same-charged lepton flavors at CERN LHC and/or ILC experiments will allow one to measure the neutrino mass parameters that neutrino oscillation experiments are insensitive to, including the neutrino mass hierarchy, lightest neutrino mass, and Majorana phases.
Instrument for the measurement and determination of chemical pulse column parameters
Marchant, Norman J.; Morgan, John P.
1990-01-01
An instrument for monitoring and measuring pneumatic driving force pulse parameters applied to chemical separation pulse columns obtains real time pulse frequency and root mean square amplitude values, calculates column inch values and compares these values against preset limits to alert column operators to the variations of pulse column operational parameters beyond desired limits.
Determination of Kinetic Parameters from Steady-State Microdisk Voltammograms
1988-01-01
characteristic parameters of voltammetric curves (i.e., constants without special expertise, instruments, or mathematical limiting current, half -wave...was then used to calculate based and subjects suitable data to alternative ways of analysis. the reversible half -wave potential (eq 14) assuming DR/Do...apparent half -wave potential to more positive values (for oxidations) and decreases the slope and lineant, Irk 0of the plot. Equation II may be used in two
Determination of combustion parameters using engine crankshaft speed
NASA Astrophysics Data System (ADS)
Taglialatela, F.; Lavorgna, M.; Mancaruso, E.; Vaglieco, B. M.
2013-07-01
Electronic engine controls based on real time diagnosis of combustion process can significantly help in complying with the stricter and stricter regulations on pollutants emissions and fuel consumption. The most important parameter for the evaluation of combustion quality in internal combustion engines is the in-cylinder pressure, but its direct measurement is very expensive and involves an intrusive approach to the cylinder. Previous researches demonstrated the direct relationship existing between in-cylinder pressure and engine crankshaft speed and several authors tried to reconstruct the pressure cycle on the basis of the engine speed signal. In this paper we propose the use of a Multi-Layer Perceptron neural network to model the relationship between the engine crankshaft speed and some parameters derived from the in-cylinder pressure cycle. This allows to have a non-intrusive estimation of cylinder pressure and a real time evaluation of combustion quality. The structure of the model and the training procedure is outlined in the paper. A possible combustion controller using the information extracted from the crankshaft speed information is also proposed. The application of the neural network model is demonstrated on a single-cylinder spark ignition engine tested in a wide range of speeds and loads. Results confirm that a good estimation of some combustion pressure parameters can be obtained by means of a suitable processing of crankshaft speed signal.
Automated inference procedure for the determination of cell growth parameters
NASA Astrophysics Data System (ADS)
Harris, Edouard A.; Koh, Eun Jee; Moffat, Jason; McMillen, David R.
2016-01-01
The growth rate and carrying capacity of a cell population are key to the characterization of the population's viability and to the quantification of its responses to perturbations such as drug treatments. Accurate estimation of these parameters necessitates careful analysis. Here, we present a rigorous mathematical approach for the robust analysis of cell count data, in which all the experimental stages of the cell counting process are investigated in detail with the machinery of Bayesian probability theory. We advance a flexible theoretical framework that permits accurate estimates of the growth parameters of cell populations and of the logical correlations between them. Moreover, our approach naturally produces an objective metric of avoidable experimental error, which may be tracked over time in a laboratory to detect instrumentation failures or lapses in protocol. We apply our method to the analysis of cell count data in the context of a logistic growth model by means of a user-friendly computer program that automates this analysis, and present some samples of its output. Finally, we note that a traditional least squares fit can provide misleading estimates of parameter values, because it ignores available information with regard to the way in which the data have actually been collected.
A Quantitative Approach to Determine Analogous Areas Using Environmental Parameters
2008-03-01
determining the analogous areas. Instead of a MATLAB-based fuzzy logic approach, this method uses ArcMap software as a tool for performing analogous...area searches and display of results. This method is more efficient and user-friendly than the fuzzy logic approach, and allows users to easily...addition, a different approach is used in determining the analogous areas. Instead of a MATLAB-based, fuzzy logic approach, this method uses ArcMap
Determination of Modal Parameters from Experimental Frequency Response Data.
1978-12-01
MILLERUNCLASSIFIED AFITCTC 1A NL mhhIhIIIIIIIIu Il lllllllllfl EIIEIIEIIIEEI IIIIIIIIIIIIIu IEEEEEIIIIIIIE IIEEEE-EI-EII -iii1 � 11jW8 1 2... TIPLER OF DAMPING MATR- 5 PARAMETER ESTIMATION 7. ERROR w 0.97242 0.0 Ci 0.11493 0.0 2 0.28362 0.0 C2 0.14715 0.0 mode F0.05735 /-347.521 0.02M 1 L 1 0T 0
A new technology for determining transport parameters in porous media
Conca, J.L.; Wright, J.
1995-12-31
The UFA Method can directly and rapidly measure transport parameters for any porous medium over a wide range of water contents and conditions. UFA results for subsurface sediments at a mixed-waste disposal site at the Hanford Site in Washington State provided the data necessary for detailed hydrostratigraphic mapping, subsurface flux and recharge distributions, and subsurface chemical mapping. Seven hundred unsaturated conductivity measurements along with pristine pore water extractions were obtained in only six months using the UFA. These data are used to provide realistic information to conceptual models, predictive models and restoration strategies.
Localization of microseismic events and determination of source parameters
NASA Astrophysics Data System (ADS)
Mokshin, E. V.; Berezhnoi, D. V.
2016-11-01
We examine the problem of localization determining and a microseismic moment tensor of single microseismic event in the presence of strongly correlated noise. This is a typical problem occurring in monitoring of microseismic events from a daylight surface under conditions of a producing field or surface monitoring of hydraulic fracturing. We offer the solution to this problem based on the method of maximum likelihood. The article presents of decision of this problem and the results of numerical experiments. We discuss some features and problems of the proposed approach and estimate the required computing resources. We develop the problem of determination direction of fracture propagation from microseismic event.
Barrios, Joaquin; Willson, John
2017-04-01
Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess change in these forces that accompany load-modifying interventions, minimum detectable change (MDC) thresholds must be established. The primary study purpose was to derive MDCs for medial tibiofemoral peak force and force impulse during walking. The secondary purpose was to identify the proportions of individuals exhibiting reductions greater than these MDCs when walking with lateral foot wedging. Eight healthy individuals provided 3-dimensional gait data over 3 test sessions to serve as inputs for an inverse dynamics-driven medial tibiofemoral contact force model, from which MDCs for peak force and impulse were derived. The MDC was 0.246 BW (8.7%) for peak force and 0.0385 BW∙s (3.7%) for impulse. Then, 25 healthy individuals provided gait data by walking with and without 6° laterally wedged foot orthoses, and the proportion of individuals exhibiting changes in medial tibiofemoral contact peak force and impulse values exceeding the MDC threshold was determined. For impulse and peak force, 52% and 4% of participants exhibited a decrease exceeding the MDC, respectively. In summary, medial tibiofemoral contact force MDCs were derived, with impulse showing greater sensitivity than peak force to the effects of a biomechanical intervention.
Wales, David J; Yildirim, Ilyas
2017-04-13
With current advancements in RNA based therapeutics, it is becoming crucial to utilize theoretical and computational methods to describe properly the physical properties of RNA molecules. NMR and X-ray crystallography are two powerful techniques for investigating structural properties. However, if the RNA molecules are complex or dynamic, these methods might not be adequate. For computational approaches, the quality of the force field will determine accuracy of our predictions. In this contribution, we revise the α/γ torsional parameters of RNA for amber force field using a model system representing an RNA dimer backbone. Combined with revised χ torsional parameters, previously shown to improve computational predictions, we benchmarked the revised force field on five single-stranded RNA (ssRNA) tetramers, three RNA dodecamer duplexes, and an RNA hairpin. A total of 60 μs of molecular dynamics (MD) simulations were run. We also employ the discrete path sampling (DPS) approach to compare the predictions for the revised amber force field with those for amber10. Our results indicate that the unphysical states observed with amber10 in ssRNA MD simulations are suppressed for the revised amber force field. In line with NMR experimental observations, incorporation of the revised α/γ and χ torsional parameters leads to A-form-like conformational states as the most favorable ssRNA tetramer conformations. Furthermore, the revised force field maintains the A-form geometry in regular RNA duplexes. Our revised amber force field for RNA should therefore improve structural and thermodynamic predictions for challenging RNA systems.
Dooley, Adam; Ma, Ye; Zhang, Yanxin
2015-01-01
Forearm crutches are a commonly used assistive device to aid the ambulation of people with lower limb impairment. Due to the structure of the joints of the upper limb, the loading patterns during crutch-walking can be detrimental to the user. Shock-absorbed or compliant crutches may reduce ground contact impact, potentially benefitting the user. In this study, the authors performed a biomechanical evaluation of a shock absorber crutch, which uses an elastomeric system to absorb impact. Ground reaction forces (GRFs) and spatiotemporal parameters were compared between shock absorbed and standard crutches. Results indicate no significant differences to spatiotemporal parameters and peak ground reaction forces between the crutches. There is an initial impact spike during crutch strike when using shock absorbed crutches, after which the rate of force development is moderately decreased when compared with a standard crutch. The practical benefit of a small reduction in force is questionable and more work must be undertaken to further optimise shock absorber design.
Determination of nuclear tracks parameters on sequentially etched PADC detectors
NASA Astrophysics Data System (ADS)
Horwacik, Tomasz; Bilski, Pawel; Koerner, Christine; Facius, Rainer; Berger, Thomas; Nowak, Tomasz; Reitz, Guenther; Olko, Pawel
Polyallyl Diglycol Carbonate (PADC) detectors find many applications in radiation protection. One of them is the cosmic radiation dosimetry, where PADC detectors measure the linear energy transfer (LET) spectra of charged particles (from protons to heavy ions), supplementing TLD detectors in the role of passive dosemeter. Calibration exposures to ions of known LET are required to establish a relation between parameters of track observed on the detector and LET of particle creating this track. PADC TASTRAK nuclear track detectors were exposed to 12 C and 56 Fe ions of LET in H2 O between 10 and 544 keV/µm. The exposures took place at the Heavy Ion Medical Accelerator (HIMAC) in Chiba, Japan in the frame of the HIMAC research project "Space Radiation Dosimetry-Ground Based Verification of the MATROSHKA Facility" (20P-240). Detectors were etched in water solution of NaOH with three different temperatures and for various etching times to observe the appearance of etched tracks, the evolution of their parameters and the stability of the etching process. The applied etching times (and the solution's concentrations and temperatures) were: 48, 72, 96, 120 hours (6.25 N NaOH, 50 O C), 20, 40, 60, 80 hours (6.25 N NaOH, 60 O C) and 8, 12, 16, 20 hours (7N NaOH, 70 O C). The analysis of the detectors involved planimetric (2D) measurements of tracks' entrance ellipses and mechanical measurements of bulk layer thickness. Further track parameters, like angle of incidence, track length and etch rate ratio were then calculated. For certain tracks, results of planimetric measurements and calculations were also compared with results of optical track profile (3D) measurements, where not only the track's entrance ellipse but also the location of the track's tip could be directly measured. All these measurements have been performed with the 2D/3D measurement system at DLR. The collected data allow to create sets of V(LET in H2 O) calibration curves suitable for short, intermediate and
Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.
2012-08-01
This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of H{sub {alpha}} and the H{sub {beta}} lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.
NASA Astrophysics Data System (ADS)
Cristofolini, Andrea; Neretti, Gabriele; Borghi, Carlo A.
2012-08-01
This work proposes an experimental analysis on the magneto hydro dynamic (MHD) interaction induced by a magnetic test body immersed into a hypersonic argon flow. The characteristic plasma parameters are measured. They are related to the voltages arising in the Hall direction and to the variation of the fluid dynamic properties induced by the interaction. The tests have been performed in a hypersonic wind tunnel at Mach 6 and Mach 15. The plasma parameters are measured in the stagnation region in front of the nozzle of the wind tunnel and in the free stream region at the nozzle exit. The test body has a conical shape with the cone axis in the gas flow direction and the cone vertex against the flow. It is placed at the nozzle exit and is equipped with three permanent magnets. In the configuration adopted, the Faraday current flows in a closed loop completely immersed into the plasma of the shock layer. The electric field and the pressure variation due to MHD interaction have been measured on the test body walls. Microwave adsorption measurements have been used for the determination of the electron number density and the electron collision frequency. Continuum recombination radiation and line radiation emissions have been detected. The electron temperature has been determined by means of the spectroscopic data by using different methods. The electron number density has been also determined by means of the Stark broadening of Hα and the Hβ lines. Optical imaging has been utilized to visualize the pattern of the electric current distribution in the shock layer around the test body. The experiments show a considerable effect of the electromagnetic forces produced by the MHD interaction acting on the plasma flow around the test body. A comparison of the experimental data with simulation results shows a good agreement.
Determining H0 with Bayesian hyper-parameters
NASA Astrophysics Data System (ADS)
Cardona, Wilmar; Kunz, Martin; Pettorino, Valeria
2017-03-01
We re-analyse recent Cepheid data to estimate the Hubble parameter H0 by using Bayesian hyper-parameters (HPs). We consider the two data sets from Riess et al. 2011 and 2016 (labelled R11 and R16, with R11 containing less than half the data of R16) and include the available anchor distances (megamaser system NGC4258, detached eclipsing binary distances to LMC and M31, and MW Cepheids with parallaxes), use a weak metallicity prior and no period cut for Cepheids. We find that part of the R11 data is down-weighted by the HPs but that R16 is mostly consistent with expectations for a Gaussian distribution, meaning that there is no need to down-weight the R16 data set. For R16, we find a value of H0 = 73.75 ± 2.11 km s‑1 Mpc‑1 if we use HPs for all data points (including Cepheid stars, supernovae type Ia, and the available anchor distances), which is about 2.6 σ larger than the Planck 2015 value of H0 = 67.81 ± 0.92 km s‑1 Mpc‑1 and about 3.1 σ larger than the updated Planck 2016 value 66.93 ± 0.62 km s‑1 Mpc‑1. If we perfom a standard χ2 analysis as in R16, we find H0 = 73.46 ± 1.40 (stat) km s‑1 Mpc‑1. We test the effect of different assumptions, and find that the choice of anchor distances affects the final value significantly. If we exclude the Milky Way from the anchors, then the value of H0 decreases. We find however no evident reason to exclude the MW data. The HP method used here avoids subjective rejection criteria for outliers and offers a way to test datasets for unknown systematics.
Lomboy, Gilson; Sundararajan, Sriram; Wang Kejin; Subramaniam, Shankar
2011-11-15
A method for determining Hamaker constant of cementitious materials is presented. The method involved sample preparation, measurement of adhesion force between the tested material and a silicon nitride probe using atomic force microscopy in dry air and in water, and calculating the Hamaker constant using appropriate contact mechanics models. The work of adhesion and Hamaker constant were computed from the pull-off forces using the Johnson-Kendall-Roberts and Derjagin-Muller-Toropov models. Reference materials with known Hamaker constants (mica, silica, calcite) and commercially available cementitious materials (Portland cement (PC), ground granulated blast furnace slag (GGBFS)) were studied. The Hamaker constants of the reference materials obtained are consistent with those published by previous researchers. The results indicate that PC has a higher Hamaker constant than GGBFS. The Hamaker constant of PC in water is close to the previously predicted value C{sub 3}S, which is attributed to short hydration time ({<=} 45 min) used in this study.
NEUROMUSCULAR DETERMINANTS OF FORCE COORDINATION DURING MULTIDIGIT GRASPING
Johnston, J. A.; Winges, S. A.; Santello, M.
2007-01-01
The biomechanical structure of the hand and its underlying neurophysiology contribute to the coordination of the kinematics and kinetics necessary for multidigit grasping. We recently examined the neural organization of inputs to different extrinsic finger flexors during multi‐digit object hold and found moderate to strong motor unit short‐term synchrony. This suggests a common neural input to the motoneurons innervating these different hand muscles/muscle compartments, which may in turn influence the coordination of grip forces. To further characterize this common input to the hand muscles during multidigit grasping, we used the frequency‐based measure of coherence. Motor unit coherence provides information with regards to the oscillatory frequency of a common input, as well as the coupling of the discharges of a motor unit pair at both short and long latencies. Preliminary results indicate that a large proportion of trials are characterized by significant coherence in the 1–12 Hz frequency range, which is more pronounced in the within‐ than between‐muscle/muscle compartment analysis. This indicates a differential organization of common oscillatory inputs to pairs of motoneurons innervating the same vs. different muscles/ muscle compartments. The functional role of the 1–12 Hz oscillatory modulation of motor unit behavior is currently being investigated. PMID:17271343
Codon Usage Bias and Determining Forces in Taenia solium Genome.
Yang, Xing; Ma, Xusheng; Luo, Xuenong; Ling, Houjun; Zhang, Xichen; Cai, Xuepeng
2015-12-01
The tapeworm Taenia solium is an important human zoonotic parasite that causes great economic loss and also endangers public health. At present, an effective vaccine that will prevent infection and chemotherapy without any side effect remains to be developed. In this study, codon usage patterns in the T. solium genome were examined through 8,484 protein-coding genes. Neutrality analysis showed that T. solium had a narrow GC distribution, and a significant correlation was observed between GC12 and GC3. Examination of an NC (ENC vs GC3s)-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENC (the effective number of codons) values were detected below the expected curve, suggesting that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally. We also identified 26 optimal codons in the T. solium genome, all of which ended with either a G or C residue. These optimal codons in the T. solium genome are likely consistent with tRNAs that are highly expressed in the cell, suggesting that mutational and translational selection forces are probably driving factors of codon usage bias in the T. solium genome.
NASA Astrophysics Data System (ADS)
Ruta, Sergiu; Hovorka, Ondrej; Huang, Pin-Wei; Wang, Kangkang; Ju, Ganping; Chantrell, Roy
2017-03-01
The generic problem of extracting information on intrinsic particle properties from the whole class of interacting magnetic fine particle systems is a long standing and difficult inverse problem. As an example, the Switching Field Distribution (SFD) is an important quantity in the characterization of magnetic systems, and its determination in many technological applications, such as recording media, is especially challenging. Techniques such as the first order reversal curve (FORC) methods, were developed to extract the SFD from macroscopic measurements. However, all methods rely on separating the contributions to the measurements of the intrinsic SFD and the extrinsic effects of magnetostatic and exchange interactions. We investigate the underlying physics of the FORC method by applying it to the output predictions of a kinetic Monte-Carlo model with known input parameters. We show that the FORC method is valid only in cases of weak spatial correlation of the magnetisation and suggest a more general approach.
Ruta, Sergiu; Hovorka, Ondrej; Huang, Pin-Wei; Wang, Kangkang; Ju, Ganping; Chantrell, Roy
2017-01-01
The generic problem of extracting information on intrinsic particle properties from the whole class of interacting magnetic fine particle systems is a long standing and difficult inverse problem. As an example, the Switching Field Distribution (SFD) is an important quantity in the characterization of magnetic systems, and its determination in many technological applications, such as recording media, is especially challenging. Techniques such as the first order reversal curve (FORC) methods, were developed to extract the SFD from macroscopic measurements. However, all methods rely on separating the contributions to the measurements of the intrinsic SFD and the extrinsic effects of magnetostatic and exchange interactions. We investigate the underlying physics of the FORC method by applying it to the output predictions of a kinetic Monte-Carlo model with known input parameters. We show that the FORC method is valid only in cases of weak spatial correlation of the magnetisation and suggest a more general approach. PMID:28338056
Method for experimental determination of flutter speed by parameter identification
NASA Technical Reports Server (NTRS)
Nissim, E.; Gilyard, Glenn B.
1989-01-01
A method for flight flutter testing is proposed which enables one to determine the flutter dynamic pressure from flights flown far below the flutter dynamic pressure. The method is based on the identification of the coefficients of the equations of motion at low dynamic pressures, followed by the solution of these equations to compute the flutter dynamic pressure. The initial results of simulated data reported in the present work indicate that the method can accurately predict the flutter dynamic pressure, as described. If no insurmountable difficulties arise in the implementation of this method, it may significantly improve the procedures for flight flutter testing.
Hyun, Seung-Hyun; Kim, Young-Pyo; Ryew, Che-Cheong
2016-01-01
This study aimed to analyze an effect on the parameters of high-heel shoe and transfer time of ground reaction force during level walking and subjects participated were composed of adult female subjects (n=13) of 20s with height of high heel (0 cm, 9 cm, respectively). Instrument used for the study was 1 set force plate (AMTI-OR9-7) and sampling rate for data collection of analysis parameters was set-up at 1,000 Hz. The revelation of required coefficient of friction (RCOF) maximum showed significant difference with more rapid than that of 1st peak vertical force (1 PVF). Transfer time of body weight showed significant difference with more delay at 9 cm than that of 0 cm. RCOF required more frictional force required because PVF showed significant difference with larger value on 9 cm than that of 3 cm at 1 PVF. Both center of pressure (COP) x and COPy showed rather less displacement on 9 cm than that of 0 cm. In addition, level walking by high heel shoe did not control efficiently the ground reaction force due to restricted control capacity of coefficient of frictional force and therefore could suggest an inducement of muscle fatigue, heightening a possibility of sliding and falling due to decrease of frictional force. PMID:27807524
Internal photoemission in molecular junctions: parameters for interfacial barrier determinations.
Fereiro, Jerry A; Kondratenko, Mykola; Bergren, Adam Johan; McCreery, Richard L
2015-01-28
The photocurrent spectra for large-area molecular junctions are reported, where partially transparent copper top contacts permit illumination by UV-vis light. The effect of variation of the molecular structure and thickness are discussed. Internal photoemission (IPE), a process involving optical excitation of hot carriers in the contacts followed by transport across internal system barriers, is dominant when the molecular component does not absorb light. The IPE spectrum contains information regarding energy level alignment within a complete, working molecular junction, with the photocurrent sign indicating transport through either the occupied or unoccupied molecular orbitals. At photon energies where the molecular layer absorbs, a secondary phenomenon is operative in addition to IPE. In order to distinguish IPE from this secondary mechanism, we show the effect of the source intensity as well as the thickness of the molecular layer on the observed photocurrent. Our results clearly show that the IPE mechanism can be differentiated from the secondary mechanism by the effects of variation of experimental parameters. We conclude that IPE can provide valuable information regarding interfacial energetics in intact, working molecular junctions, including clear discrimination of charge transport mediated by electrons through unoccupied system orbitals from that mediated by hole transport through occupied system orbitals.
Determination and adjustment of drying parameters of Tunisian ceramic bodies
NASA Astrophysics Data System (ADS)
Mahmoudi, Salah; Bennour, Ali; Srasra, Ezzeddine; Zargouni, Fouad
2016-12-01
This work deals with the mineralogical, physico-chemical and geotechnical analyses of representative Aptian clays in the north-east of Tunisia. X-ray diffraction reveals a predominance of illite (50-60 wt%) associated with kaolinite and interstratified illite/smectite. The accessory minerals detected in raw materials are quartz, calcite and Na-feldspar. The average amounts of silica, alumina and alkalis are 52, 20 and 3.5 wt%, respectively. The contents of lime and iron vary between 4 and 8 wt %. The plasticity test shows medium values of plasticity index (16-28 wt%). The linear drying shrinkage is weak (less than 0.99 wt%) which makes these clays suitable for fast drying. The firing shrinkage and expansion are limited. A lower firing and drying temperature allow significant energy savings. Currently, these clays are used in the industry for manufacturing earthenware tiles. For the optimum exploitation of the clay materials and improvement of production conditions, a mathematical formulationis established for the drying parameters. These models predict drying shrinkage (d), bending strength after drying (b) and residual moisture (r) from initial moisture (m) and pressing pressure (p).
Experimental Determination of Metal Fuel Point Defect Parameters
Fluss, M J; McCall, S
2008-06-03
Nuclear metallic fuels are one of many options for advanced nuclear fuel cycles because they provide dimensional stability, mechanical integrity, thermal efficiency, and irradiation resistance while the associated pyro-processing is technically relevant to concerns about proliferation and diversion of special nuclear materials. In this presentation we will discuss recent success that we have had in studying isochronal annealing of damage cascades in Pu and Pu(Ga) arising from the self-decay of Pu as well as the annealing characteristics of noninteracting point defect populations produced by ion accelerator irradiation. Comparisons of the annealing properties of these two populations of defects arising from very different source terms are enlightening and point to complex defect and mass transport properties in the plutonium specimens which we are only now starting to understand as a result of many follow-on studies. More importantly however, the success of these measurements points the way to obtaining important mass transport parameters for comparison with theoretical predictions or to use directly in existing and future materials modeling of radiation effects in nuclear metallic fuels. The way forward on such measurements and the requisite theory and modeling will be discussed.
Soil hydrodynamic parameter determination using Ground-Penetrating Radar monitoring
NASA Astrophysics Data System (ADS)
Leger, E.
2015-12-01
Soil hydraulic properties, represented by the soil water retention andhydraulic conductivity functions, dictate water flow in the vadosezone, from surface to aquifers. Understanding the water flow dynamichas important implications for estimating available water resourcesand flood forecasting. It is also crucial in evaluating the dynamicsof chemical pollutants in soil and in assessing the risks ofgroundwater pollution. Ground Penetrating Radar is a geophysicalmethod particularly suited to measure contrasts of electromagneticparameters such as those created by water content variations in soils.We developed coupled hydrodynamic and electromagnetic numericalmodeling to invert the two way travel times associated withreflections corresponding to strong dielectric permittivity contrastssuch as wetting front and wetting bulb.We will present three different techniques using Ground PenetratingRadar monitoring: one using a single ring infiltrometer, an other oneusing shallow boreholes and the last one being a laboratory largecylindrical tank in which we applied different water table levels.We used the parametrical Mualem-van Genuchten model to fit soil-waterretention and hydraulic conductivity functions. Using GroundPenetrating Radar data inversion, we optimized the Mualem-vanGenuchten parameters using Shuffled Complex Evolution algorithm.Results are compared with classical laboratory and field methods.
Solar radiation force modeling for TDRS orbit determination
NASA Technical Reports Server (NTRS)
Lee, T.; Lucas, M. J.; Shanklin, R. E., Jr.
1981-01-01
The relative orbit determination accuracies resulting from several TDRS models are evaluated. These models include spherical, single-plate, and restricted two-plate models. The plate models can be adjusted in both area and reflectivity through differential correction. The restricted two-plate model has an Earth-pointing plate and a solar plate; the orientation of the solar plate is restricted to rotation about an axis perpendicular to the satellite's orbital plane.
Comprehensive Methods for Determining Space Effects on Air Force Systems
2009-08-04
condensation on ice, Part I: Non-HN03 Constituent of NOy Condensing on Low Temperature Upper Tropospheric Cirrus Cloud Particles,"/ Geophys. Res. Ill...Kinetic limitations, a possible ’ cloud clock’ for determining cloud parcel lifetime," J. Geophys. Res. 112, D12209 (2007). W. Geppert, A...34Electron attachment to SF6 under well defined conditions: Comparison of statistical modeling results to experiments," J. Phys. Conf. Series. 115,012019
Plank, J.; Sachsenhauser, B.; Reese, J. de
2010-05-15
For adsorption of three different allylether-based PCE superplasticizers on CaCO{sub 3} surface, the thermodynamic parameters DELTAH, DELTAS and DELTAG were determined experimentally. The GIBBS standard free energy of adsorption DELTAG{sub 0ads}, the standard enthalpy of adsorption DELTAH{sub 0ads} and the standard entropy of adsorption DELTAS{sub 0ads} applying to an unoccupied CaCO{sub 3} surface were obtained via a linear regression of ln K (equilibrium constant) versus 1 / T (VAN'T HOFF plot). Additionally, the thermodynamic parameters characteristic for a CaCO{sub 3} surface loaded already with polymer (isosteric conditions) were determined using a modified CLAUSIUS-CLAPEYRON equation. For all PCE molecules, negative DELTAG values were found, indicating that adsorption of these polymers is energetically favourable and a spontaneous process. Adsorption of PCEs possessing short side chains is mainly instigated by electrostatic attraction and a release of enthalpy. Contrary to this, adsorption of PCEs with long side chains occurs because of a huge gain in entropy. The gain in entropy results from the release of counter ions attached to the carboxylate groups of the polymer backbone and of water molecules and ions adsorbed on the CaCO{sub 3} surface. With increased surface loading, however, DELTAG{sub isosteric} decreases and adsorption ceases when DELTAG becomes 0. The presence of Ca{sup 2+} ions in the pore solution strongly impacts PCE adsorption, due to complexation of carboxylate groups and a reduced anionic charge amount of the molecule. In the presence of Ca{sup 2+}, adsorption of allylether-based PCEs is almost exclusively driven by a gain in entropy. Consequently, PCEs should produce a strong entropic effect upon adsorption to be effective cement dispersants. Molecular architecture, anionic charge density and molecular weight as well as the type of anchor groups present in a superplasticizer determine whether enthalpy or entropy is the dominant force for
Optimal Parameter Determination for Tritiated Water Storage in Polyacrylic Networks
Postolache, C.; Matei, Lidia; Georgescu, Rodica; Ionita, Gh.
2005-07-15
Due to the remarkable capacity of water retaining, croslinked polyacrylic acids (PAA) represent an interesting alternative for tritiated water trapping. The study was developed on radiolytical processes in PAA:HTO systems derivated from irradiation of polymeric network by disintegration of tritium atoms from HTO. The aim of these studies is the identification of polymeric structures and optimal storage conditions.Sol and gel fractions were determinated by radiometrical methods using PAA labeled with 14-C at carboxylic groups and T at main chains of the polymer. Simulation of radiolytical processes was realized using {gamma} radiation field emitted by a irradiation source of 60-Co which ensures a maximum of absorbed dose rate of 3 kGy/h. Self-radiolytical effects were investigated using labeled PAA in HTO with great radioactive concentration (37-185 GBq/mL). The experiment suggests as optimum for HTO storage as tritium liquid wastes a 1:30 PAA:HTO swelling degree at 18.5-37 MBqL. HTO radioactive concentration.RES studies of radiolytical processes were also realized on dry polyacrylic acid (PAA) and polyacrylic based hydrogels irradiated and determined at 77 K. In the study we observed the effect of swelling capacity of hydrogel o the formation of free radicals.
ERIC Educational Resources Information Center
Digilov, Rafael M.
2008-01-01
We describe a simple and very inexpensive undergraduate laboratory experiment for fast determination of Young's modulus at moderate temperatures with the aid of a force sensor. A strip-shaped specimen rigidly bolted to the force sensor forms a clamped-free cantilever beam. Placed in a furnace, it is subjected to free-bending vibrations followed by…
Experimentally Determined Plasma Parameters in a 30 cm Ion Engine
NASA Technical Reports Server (NTRS)
Sengupta, Anita; Goebel, Dan; Fitzgerald, Dennis; Owens, Al; Tynan, George; Dorner, Russ
2004-01-01
Single planar Langmuir probes and fiber optic probes are used to concurrently measure the plasma properties and neutral density variation in a 30cm diameter ion engine discharge chamber, from the immediate vicinity of the keeper to the near grid plasma region. The fiber optic probe consists of a collimated optical fiber recessed into a double bore ceramic tube fitted with a stainless steel light-limiting window. The optical fiber probe is used to measure the emission intensity of excited neutral xenon for a small volume of plasma, at various radial and axial locations. The single Langmuir probes, are used to generate current-voltage characteristics at a total of 140 spatial locations inside the discharge chamber. Assuming a maxwellian distribution for the electron population, the Langmuir probe traces provide spatially resolved measurements of plasma potential, electron temperature, and plasma density. Data reduction for the NSTAR TH8 and TH15 throttle points indicates an electron temperature range of 1 to 7.9 eV and an electron density range of 4e10 to le13 cm(sup -3), throughout the discharge chamber, consistent with the results in the literature. Plasma potential estimates, computed from the first derivative of the probe characteristic, indicate potential from 0.5V to 11V above the discharge voltage along the thruster centerline. These values are believed to be excessively high due to the sampling of the primary electron population along the thruster centerline. Relative neutral density profiles are also obtained with a fiber optic probe sampling photon flux from the 823.1 nm excited to ground state transition. Plasma parameter measurements and neutral density profiles will be presented as a function of probe location and engine discharge conditions. A discussion of the measured electron energy distribution function will also be presented, with regards to variation from pure maxwellian. It has been found that there is a distinct primary population found along
NASA Astrophysics Data System (ADS)
Castro, Luz Angelica; Hoyos, Mauricio
2016-04-01
We propose an experimental methodology to determine the secondary Bjerknes force between rigid particles. Measurements done for different particles sizes showed acoustical inter particles interactions. We use and extend the methodology presented in a previous work. The determination of this force will lead us a better understanding of the aggregation process in acoustic resonators. We report in this work, the results of two parabolic flights campaigns performed at the Airbus A300 ZERO-G (Novespace, France).
NASA Technical Reports Server (NTRS)
Batterson, J. G.
1986-01-01
The successful parametric modeling of the aerodynamics for an airplane operating at high angles of attack or sideslip is performed in two phases. First the aerodynamic model structure must be determined and second the associated aerodynamic parameters (stability and control derivatives) must be estimated for that model. The purpose of this paper is to document two versions of a stepwise regression computer program which were developed for the determination of airplane aerodynamic model structure and to provide two examples of their use on computer generated data. References are provided for the application of the programs to real flight data. The two computer programs that are the subject of this report, STEP and STEPSPL, are written in FORTRAN IV (ANSI l966) compatible with a CDC FTN4 compiler. Both programs are adaptations of a standard forward stepwise regression algorithm. The purpose of the adaptation is to facilitate the selection of a adequate mathematical model of the aerodynamic force and moment coefficients of an airplane from flight test data. The major difference between STEP and STEPSPL is in the basis for the model. The basis for the model in STEP is the standard polynomial Taylor's series expansion of the aerodynamic function about some steady-state trim condition. Program STEPSPL utilizes a set of spline basis functions.
Determination of the Asynchronous Load on a Rotor from the Measured Internal Forces
NASA Astrophysics Data System (ADS)
Phan, A.-V.; Reynaud, G.
1997-09-01
Experimental contributions currently play an important role in determining hydraulic forces due to cavitation. Up to the present date, there is no computational analysis which has proven to be successful in this domain. Experiments are usually carried out to measure the resulting internal forces in a model because these forces are crucial for designing elements under cavitational flows. This paper presents a numerical approach using the theory of rotordynamics coupled with the finite element method (FEM) to determine the hydraulic load on a rotor from the internal forces measured in a cross-section of the rotor. Once the load is found, a program developed can be used to compute the internal forces in any cross-section of interest and to evaluate dynamic effects on the rotor. Two illustrative examples are presented to show the validity of this approach.
NASA Technical Reports Server (NTRS)
Nissim, Eli
1990-01-01
The effectiveness of aerodynamic excitation is evaluated analytically in conjunction with the experimental determination of flutter dynamic pressure by parameter identification. Existing control surfaces were used, with an additional vane located at the wingtip. The equations leading to the identification of the equations of motion were reformulated to accommodate excitation forces of aerodynamic origin. The aerodynamic coefficients of the excitation forces do not need to be known since they are determined by the identification procedure. The 12 degree-of-freedom numerical example treated in this work revealed the best wingtip vane locations, and demonstrated the effectiveness of the aileron-vane excitation system. Results from simulated data gathered at much lower dynamic pressures (approximately half the value of flutter dynamic pressure) predicted flutter dynamic pressures with 2-percent errors.
ERIC Educational Resources Information Center
Skrzek, Anna; Stefanska, Malgorzata
2012-01-01
The aim of the paper was to evaluate changes in muscle force-velocity parameters (F-v) in elderly women subjected to physical exercise. The examinations encompassed 20 women, aged 62-71, who were students at the University of the Third Age in Wroclaw. The evaluation of flexors and extensors of the knee joint, as well as flexors and extensors of…
NASA Astrophysics Data System (ADS)
El Bouami, Souhail; Habak, Malek; Franz, Gérald; Velasco, Raphaël; Vantomme, Pascal
2016-10-01
Composite materials are increasingly used for structural parts in the aeronautic industries. Carbon Fiber-Reinforced Plastics (CFRP) are often used in combination with metallic materials, mostly aluminium alloys. This raises new problems in aircraft assembly. Delamination is one of these problems. In this study, CFRP/Al-Li stacks is used as experimental material for investigation effect of interaction of cutting parameters (cutting speed and feed rate) and tool geometry on delamination and thrust forces in drilling operation. A plan of experiments, based on Taguchi design method, was employed to investigate the influence of tool geometry and in particular the point angle and cutting parameters on delamination and axial effort. The experimental results demonstrate that the feed rate is the major parameter and the importance of tool point angle in delamination and thrust forces in the stacks were shown.
Murzyn, Krzysztof; Bratek, Maciej; Pasenkiewicz-Gierula, Marta
2013-12-27
OPLS All-Atom (OPLS/AA) is a generic all-atom force field which was fine-tuned to accurately reproduce condensed phase properties of organic liquids. Its application in modeling of lipid membranes is, however, limited mainly due to the inability to correctly describe phase behavior and organization of the hydrophobic core of the model lipid bilayers. Here we report new OPLS/AA parameters for n-pentadecane, methyl acetate, and dimethyl phosphate anion. For the new force field parameters, we show very good agreement between calculated and numerous reference data, including liquid density, enthalpy of vaporization, free energy of hydration, and selected transport properties. The new OPLS/AA parameters have been used in successful submicrosecond MD simulations of bilayers made of bacterial glycolipids whose results will be published elsewhere shortly.
Ponomarev, Sergei Y.; Kaminski, George A.
2011-01-01
A previously introduced POSSIM (POlarizable Simulations with Second order Interaction Model) force field has been extended to include parameters for alanine peptides and protein backbones. New features were introduced into the fitting protocol, as compared to the previous generation of the polarizable force field for proteins. A reduced amount of quantum mechanical data was employed in fitting the electrostatic parameters. Transferability of the electrostatics between our recently developed NMA model and the protein backbone was confirmed. Binding energy and geometry for complexes of alanine dipeptide with a water molecule were estimated and found in a good agreement with high-level quantum mechanical results (for example, the intermolecular distances agreeing within ca. 0.06Å). Following the previously devised procedure, we calculated average errors in alanine di- and tetra-peptide conformational energies and backbone angles and found the agreement to be adequate (for example, the alanine tetrapeptide extended-globular conformational energy gap was calculated to be 3.09 kcal/mol quantim mechanically and 3.14 kcal/mol with the POSSIM force field). However, we have now also included simulation of a simple alpha-helix in both gas-phase and water as the ultimate test of the backbone conformational behavior. The resulting alanine and protein backbone force field is currently being employed in further development of the POSSIM fast polarizable force field for proteins. PMID:21743799
Camilo, G.B.; Carvalho, A.R.S.; Machado, D.C.; Mogami, R.; Kasuki, L.; Gadelha, M.R.; Melo, P.L.; Lopes, A.J.
2015-01-01
The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=−0.602, P<0.001) and mean resistance (rs=−0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease. PMID:26445330
Camilo, G B; Carvalho, A R S; Machado, D C; Mogami, R; Kasuki, L; Gadelha, M R; Melo, P L; Lopes, A J
2015-10-01
The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7) vs 11.4 (9.05-17.6) Hz, P=0.023] and a lower value for mean reactance [0.32 (0.21-0.64) vs 0.49 (0.34-0.96) cm H2O/L/s2, P=0.005]. In inspiratory Q-MDCT, the acromegalic patients had higher percentages of total lung volume (TLV) for nonaerated and poorly aerated areas [0.42% (0.30-0.51%) vs 0.25% (0.20-0.32%), P=0.039 and 3.25% (2.48-3.46%) vs 1.70% (1.45-2.15%), P=0.001, respectively]. Furthermore, the acromegalic patients had higher values for total lung mass in both inspiratory and expiratory Q-MDCT [821 (635-923) vs 696 (599-769) g, P=0.021 and 844 (650-945) vs 637 (536-736) g, P=0.009, respectively]. In inspiratory Q-MDCT, TLV showed significant correlations with all FOT parameters. The TLV of hyperaerated areas showed significant correlations with intercept resistance (rs=-0.602, P<0.001) and mean resistance (rs=-0.580, P<0.001). These data showed that acromegalic patients have increased amounts of lung tissue as well as nonaerated and poorly aerated areas. Functionally, there was a loss of homogeneity of the respiratory system. Moreover, there were correlations between the structural and functional findings of the respiratory system, consistent with the pathophysiology of the disease.
Camilo, G B; Carvalho, A R S; Machado, D C; Mogami, R; Kasuki, L; Gadelha, M R; Melo, P L; Lopes, A J
2015-08-04
The aims of this study were to evaluate the forced oscillation technique (FOT) and pulmonary densitovolumetry in acromegalic patients and to examine the correlations between these findings. In this cross-sectional study, 29 non-smoking acromegalic patients and 17 paired controls were subjected to the FOT and quantification of lung volume using multidetector computed tomography (Q-MDCT). Compared with the controls, the acromegalic patients had a higher value for resonance frequency [15.3 (10.9-19.7)
McLoughlin, Neal; Lee, Stephen L; Hähner, Georg
2007-08-01
We demonstrate that the thermal response of uncalibrated atomic force microscope cantilevers can be used to extract the density and the viscosity of viscous liquids with good accuracy. Temperature dependent thermal noise spectra were measured in water/poly(ethylene glycol) mixtures. Empirical parameters characteristic of the resonance behavior of the system were extracted from data recorded for one of the solutions at room temperature. These parameters were then employed to determine both viscosity and density values of the solutions simultaneously at different temperatures. In addition, activation energies for viscous flow were determined from the viscosity values obtained. The method presented is both fast and reliable and has the potential to be applied in connection with microfluidic systems, making macroscopic amounts of liquid and separate measurements with a viscometer and a densimeter redundant.
The Social Determinants of Health in Military Forces of Iran: A Qualitative Study
Bahadori, Mohammadkarim; Sanaeinasab, Hormoz; Ghanei, Mostafa; Mehrabi Tavana, Ali; Ravangard, Ramin; Karamali, Mazyar
2015-01-01
Providing effective health interventions and achieving equity in health need to apply the community-based approaches such as social determinants of health. In the military organizations, these determinants have received less attention from the military health researchers and policymakers. Therefore, this study aimed to identify and explain the social determinants affecting the health of military forces in Iran. This was a qualitative study which was conducted in 2014. The required data were collected through semistructured interviews and analyzed through Conventional Content Analysis. The studied sample consisted of 22 military health experts, policymakers, and senior managers selected using purposeful sampling method with maximum variation sampling. MAXQDA.2007 was used to analyze the collected data. After analyzing the collected data, two main contents, that is, “general social determinants of health” and “military social determinants of health,” with 22 themes and 90 subthemes were identified as the social determinants of military forces' health. Main themes were religious rule, spirituality promotion policies, international military factors, military command, and so forth. Given the role and importance of social factors determining the military forces' health, it can be recommended that the military organizations should pay more attention to these determinants in making policies and creating social, economic, and cultural structures for their forces. PMID:26379716
Borysov, Stanislav S.; Forchheimer, Daniel; Haviland, David B.
2014-10-29
Here we present a theoretical framework for the dynamic calibration of the higher eigenmode parameters (stiffness and optical lever inverse responsivity) of a cantilever. The method is based on the tip–surface force reconstruction technique and does not require any prior knowledge of the eigenmode shape or the particular form of the tip–surface interaction. The calibration method proposed requires a single-point force measurement by using a multimodal drive and its accuracy is independent of the unknown physical amplitude of a higher eigenmode.
Borysov, Stanislav S; Forchheimer, Daniel; Haviland, David B
2014-01-01
We present a theoretical framework for the dynamic calibration of the higher eigenmode parameters (stiffness and optical lever inverse responsivity) of a cantilever. The method is based on the tip-surface force reconstruction technique and does not require any prior knowledge of the eigenmode shape or the particular form of the tip-surface interaction. The calibration method proposed requires a single-point force measurement by using a multimodal drive and its accuracy is independent of the unknown physical amplitude of a higher eigenmode.
Forchheimer, Daniel; Haviland, David B
2014-01-01
Summary We present a theoretical framework for the dynamic calibration of the higher eigenmode parameters (stiffness and optical lever inverse responsivity) of a cantilever. The method is based on the tip–surface force reconstruction technique and does not require any prior knowledge of the eigenmode shape or the particular form of the tip–surface interaction. The calibration method proposed requires a single-point force measurement by using a multimodal drive and its accuracy is independent of the unknown physical amplitude of a higher eigenmode. PMID:25383301
2013-01-01
Maximum Likelihood (ML) optimization schemes are widely used for parameter inference. They maximize the likelihood of some experimentally observed data, with respect to the model parameters iteratively, following the gradient of the logarithm of the likelihood. Here, we employ a ML inference scheme to infer a generalizable, physics-based coarse-grained protein model (which includes Go̅-like biasing terms to stabilize secondary structure elements in room-temperature simulations), using native conformations of a training set of proteins as the observed data. Contrastive divergence, a novel statistical machine learning technique, is used to efficiently approximate the direction of the gradient ascent, which enables the use of a large training set of proteins. Unlike previous work, the generalizability of the protein model allows the folding of peptides and a protein (protein G) which are not part of the training set. We compare the same force field with different van der Waals (vdW) potential forms: a hard cutoff model, and a Lennard-Jones (LJ) potential with vdW parameters inferred or adopted from the CHARMM or AMBER force fields. Simulations of peptides and protein G show that the LJ model with inferred parameters outperforms the hard cutoff potential, which is consistent with previous observations. Simulations using the LJ potential with inferred vdW parameters also outperforms the protein models with adopted vdW parameter values, demonstrating that model parameters generally cannot be used with force fields with different energy functions. The software is available at https://sites.google.com/site/crankite/. PMID:24683370
Determination of ITM Key Parameters By the Ionospheric Connection Explorer (ICON)
NASA Astrophysics Data System (ADS)
Immel, T. J.; England, S.; Mende, S. B.; Makela, J. J.; Harding, B. J.; Stephan, A. W.; Kamalabadi, F.; Heelis, R. A.; Englert, C. R.; Edelstein, J.; Forbes, J. M.; Maute, A. I.; Crowley, G.; Huba, J. D.; Harlander, J.; Swenson, G. R.; Frey, H. U.; Bust, G. S.; Gerard, J. C. M. C.; Hubert, B. A.; Rowland, D. E.; Hysell, D. L.; Saito, A.; Frey, S.; Bester, M.; Craig, W.
2014-12-01
Selected for development by NASA in 2013, ICON is a mission that will launch in 2017 to discover the source of strong day-to-day variability in Earth's space environment. Recent observations continue to raise questions about the effects and interaction of these in our geospace environment, and how these vary between extremes in solar activity. To address these, ICON will measure all key parameters of the atmosphere and ionosphere simultaneously and continuously with a combination of remote sensing and in-situ measurements. ICON will fly in a 27-degree inclination orbit with a payload designed to observe the processes of vertical wave coupling in the Ionosphere/Thermosphere/Mesosphere system, how these processes influence the state of the system itself, and how that state preconditions the system for modification by external influence (e.g. solar and solar wind forcing). ICON will remotely observe winds and temperatures in the 90-150 km region while measuring the highly variable electric field in the ionosphere on magnetically connected field lines. Simultaneous to these observations, ICON remotely observes the thermospheric composition and density, and ionospheric density in day and night. The retrievals involved and resultant precision in the determination of key parameters will be presented. The scientific return from ICON is enhanced by dynamic operational modes of the observatory that provide capabilities well beyond that afforded by a static space platform. Careful selection of these modes and the selective implementation of instrument redundancy provide the ability to operate with large technical margins that support the greatest return of science data.
NASA Technical Reports Server (NTRS)
Hagan, Ronald Donald; Norcross, Jason; DeWitt, John; Lee, Stuart M.; McCleary, Frank; Edwards, W. Brent
2006-01-01
Both motorized (T-M) and non-motorized (T-NM) treadmill locomotion are used on the International Space Station (ISS) as countermeasures to the deleterious effects of prolonged weightlessness. However, the ground reaction forces (GRF) and gait parameters of these exercise modes have not been examined. The purpose of this study was to determine if differences in GRF and gait parameters exist while walking (1.34 m/s) and running (3.13 m/s) on T-M and T-NM. Dissimilar GRF and gait parameters suggest that T-M and T-NM locomotion may elicit different physiologic effects. T-NM may result in a reduced stimulus to bone formation due to a lower LR, but an increased energy cost as a result of shorter, more frequent strides. Therefore, the usage of each mode should depend upon the desired training stimulus.
Cartagena-Rivera, Alexander X; Logue, Jeremy S; Waterman, Clare M; Chadwick, Richard S
2016-06-07
The organization of filamentous actin and myosin II molecular motor contractility is known to modify the mechanical properties of the cell cortical actomyosin cytoskeleton. Here we describe a novel method, to our knowledge, for using force spectroscopy approach curves with tipless cantilevers to determine the actomyosin cortical tension, elastic modulus, and intracellular pressure of nonadherent cells. We validated the method by measuring the surface tension of water in oil microdrops deposited on a glass surface. We extracted an average tension of T ∼ 20.25 nN/μm, which agrees with macroscopic experimental methods. We then measured cortical mechanical properties in nonadherent human foreskin fibroblasts and THP-1 human monocytes before and after pharmacological perturbations of actomyosin activity. Our results show that myosin II activity and actin polymerization increase cortex tension and intracellular pressure, whereas branched actin networks decreased them. Interestingly, myosin II activity stiffens the cortex and branched actin networks soften it, but actin polymerization has no effect on cortex stiffness. Our method is capable of detecting changes in cell mechanical properties in response to perturbations of the cytoskeleton, allowing characterization with physically relevant parameters. Altogether, this simple method should be of broad application for deciphering the molecular regulation of cell cortical mechanical properties.
Mettler, Joni A; Griffin, Lisa
2010-12-01
Muscle force potentiation affects force output during electrical stimulation. Few studies have examined stimulation train parameters that influence potentiation such as pulse number, stimulation frequency, train duration, and force-time integral and peak force produced during the train. Pulse-matched trains (100 pulses) at 7.5, 15, 25, 30, 50, and 100 Hz, and trains of varying pulse number (50, 100, and 200 pulses) at 30 and 50 Hz were delivered to the ulnar nerve of 10 (5 male, 5 female; 23.4 ± 0.9 years), healthy individuals in random order. Single twitches of the adductor pollicis muscle were elicited before and after each train with a rest interval of at least 5 min between each train. No differences in potentiation occurred across the pulse-matched trains at frequencies of 15-50 Hz (38.9 ± 5.4-44.6 ± 5.5%). Twitch force potentiation following the highest (100 Hz) and lowest (7.5 Hz) frequency trains were not significantly different and were lower than the other 100 pulse-matched trains. As pulse number increased, potentiation increased for both the 30 and 50-Hz trains. There was a significant positive correlation between force potentiation and force-time integral produced by the stimulation train, r = 0.70. The results indicate that potentiation magnitude is dependent on the force-time integral produced during the test train and the number of pulses delivered, independent of stimulation frequency.
NASA Astrophysics Data System (ADS)
Suzuki, Y.
2016-05-01
This article demonstrates the practical applicability of a method of modelling shape memory alloys (SMAs) as actuators. For this study, a pair of SMA wires was installed in an antagonistic manner to form an actuator, and a linear differential equation that describes the behaviour of the actuator’s generated force relative to its input voltage was derived for the limited range below the austenite onset temperature. In this range, hysteresis need not be considered, and the proposed SMA actuator can therefore be practically applied in linear control systems, which is significant because large deformations accompanied by hysteresis do not necessarily occur in most vibration control cases. When specific values of the parameters used in the differential equation were identified experimentally, it became clear that one of the parameters was dependent on ambient airflow velocity. The values of this dependent parameter were obtained using an additional SMA wire as a sensor. In these experiments, while the airflow distribution around the SMA wires was varied by changing the rotational speed of the fans in the wind tunnels, an input voltage was conveyed to the SMA actuator circuit, and the generated force was measured. In this way, the parameter dependent on airflow velocity was estimated in real time, and it was validated that the calculated force was consistent with the measured one.
NASA Astrophysics Data System (ADS)
Golub, V. P.; Pavlyuk, Ya. V.; Fernati, P. V.
2013-03-01
The parameters of fractional-exponential hereditary kernels for nonlinear viscoelastic materials are determined. Methods for determining the parameters used in the third-order theory of viscoelasticity and in nonlinear theories based on the similarity of primary creep curves and the similarity of isochronous creep curves are analyzed. The parameters of fractional-exponential hereditary kernels are determined and tested against experimental data for microplastic, TC-8/3-250 glass-reinforced plastics, SVAM glass-reinforced plastics. The results (tables and plots) are analyzed
NASA Astrophysics Data System (ADS)
Boden, Christopher D. J.; Pattenden, Gerald
1999-03-01
Ab initio calculations at the RHF/6-31G* and MP2/6- 31G*//RHF/6-31G* levels of theory are performed for 2-methyl-4-carboxamido-oxazoles and -thiazoles, including rotational profiles for the ring-carboxamide bond, which showed the expected conjugation and hydrogen bonding effects. On the basis of these data, newly optimised stretch, bend and torsional parameters for the AMBER* force field are derived, along with CHELPG-fitted partial atomic charges.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-09-22
... Determination and Certification Related to Colombian Armed Forces Under Section 7046(B) of the Department of...-117) (``FY 2010 SFOAA''), I hereby determine, certify, and report that the Colombian Armed Forces are... Colombian Armed Forces' progress in meeting the above-mentioned conditions, as provided in section...
Determination of the Parameter Sets for the Best Performance of IPS-driven ENLIL Model
NASA Astrophysics Data System (ADS)
Yun, Jongyeon; Choi, Kyu-Cheol; Yi, Jonghyuk; Kim, Jaehun; Odstrcil, Dusan
2016-12-01
Interplanetary scintillation-driven (IPS-driven) ENLIL model was jointly developed by University of California, San Diego (UCSD) and National Aeronaucics and Space Administration/Goddard Space Flight Center (NASA/GSFC). The model has been in operation by Korean Space Weather Cetner (KSWC) since 2014. IPS-driven ENLIL model has a variety of ambient solar wind parameters and the results of the model depend on the combination of these parameters. We have conducted researches to determine the best combination of parameters to improve the performance of the IPS-driven ENLIL model. The model results with input of 1,440 combinations of parameters are compared with the Advanced Composition Explorer (ACE) observation data. In this way, the top 10 parameter sets showing best performance were determined. Finally, the characteristics of the parameter sets were analyzed and application of the results to IPS-driven ENLIL model was discussed.
Gilgien, Matthias; Spörri, Jörg; Chardonnens, Julien; Kröll, Josef; Müller, Erich
2013-01-01
In alpine ski racing the relationships between skier kinetics and kinematics and their effect on performance and injury-related aspects are not well understood. There is currently no validated system to determine all external forces simultaneously acting on skiers, particularly under race conditions and throughout entire races. To address the problem, this study proposes and assesses a method for determining skier kinetics with a single lightweight differential global navigation satellite system (dGNSS). The dGNSS kinetic method was compared to a reference system for six skiers and two turns each. The pattern differences obtained between the measurement systems (offset ± SD) were −26 ± 152 N for the ground reaction force, 1 ± 96 N for ski friction and −6 ± 6 N for the air drag force. The differences between turn means were small. The error pattern within the dGNSS kinetic method was highly repeatable and precision was therefore good (SD within system: 63 N ground reaction force, 42 N friction force and 7 N air drag force) allowing instantaneous relative comparisons and identification of discriminative meaningful changes. The method is therefore highly valid in assessing relative differences between skiers in the same turn, as well as turn means between different turns. The system is suitable to measure large capture volumes under race conditions. PMID:23917257
NASA Astrophysics Data System (ADS)
Leclère, Quentin; Ablitzer, Frédéric; Pézerat, Charles
2015-09-01
The paper aims to combine two objectives of the Force Analysis Technique (FAT): vibration source identification and material characterization from the same set of measurement. Initially, the FAT was developed for external load location and identification. It consists in injecting measured vibration displacements in the discretized equation of motion. Two developments exist: FAT and CFAT (Corrected Force Analysis Technique) where two finite difference schemes are used. Recently, the FAT was adapted for the identification of elastic and damping properties in a structure. The principal interests are that the identification is local and allows mapping of material characteristics, the identification can be made at all frequencies, especially in medium and high frequency domains. The paper recalls the development of FAT and CFAT on beams and plates and how it can be possible to extract material characteristics in areas where no external loads are applied. Experimental validations are shown on an aluminum plate with arbitrary boundary conditions, excited by a point force and where a piece of foam is glued on a sub-surface of the plate. Contactless measurements were made using a scanning laser vibrometer. The results of FAT and CFAT are compared and discussed for material property identifications in the regions with and without foam. The excitation force identification is finally made by using the identified material properties. CFAT gives excellent results comparable to a direct measurement obtained by a piezoelectric sensor. The relevance of the corrected scheme is then underlined for both source identification and material characterization from the same measurements.
Optimization of Process Parameters of Edge Robotic Deburring with Force Control
NASA Astrophysics Data System (ADS)
Burghardt, A.; Szybicki, D.; Kurc, K.; Muszyńska, M.
2016-12-01
The issues addressed in the paper present a part of the scientific research conducted within the framework of the automation of the aircraft engine part manufacturing processes. The results of the research presented in the article provided information in which tolerances while using a robotic control station with the option of force control we can make edge deburring.
NASA Astrophysics Data System (ADS)
Mao, Albert H.; Pappu, Rohit V.
2012-08-01
Accurate models of alkali and halide ions in aqueous solution are necessary for computer simulations of a broad variety of systems. Previous efforts to develop ion force fields have generally focused on reproducing experimental measurements of aqueous solution properties such as hydration free energies and ion-water distribution functions. This dependency limits transferability of the resulting parameters because of the variety and known limitations of water models. We present a solvent-independent approach to calibrating ion parameters based exclusively on crystal lattice properties. Our procedure relies on minimization of lattice sums to calculate lattice energies and interionic distances instead of equilibrium ensemble simulations of dense fluids. The gain in computational efficiency enables simultaneous optimization of all parameters for Li+, Na+, K+, Rb+, Cs+, F-, Cl-, Br-, and I- subject to constraints that enforce consistency with periodic table trends. We demonstrate the method by presenting lattice-derived parameters for the primitive model and the Lennard-Jones model with Lorentz-Berthelot mixing rules. The resulting parameters successfully reproduce the lattice properties used to derive them and are free from the influence of any water model. To assess the transferability of the Lennard-Jones parameters to aqueous systems, we used them to estimate hydration free energies and found that the results were in quantitative agreement with experimentally measured values. These lattice-derived parameters are applicable in simulations where coupling of ion parameters to a particular solvent model is undesirable. The simplicity and low computational demands of the calibration procedure make it suitable for parametrization of crystallizable ions in a variety of force fields.
Determining parameters and mechanisms of colloid retention and release in porous media
Technology Transfer Automated Retrieval System (TEKTRAN)
A framework is presented to determine fundamental parameters and mechanisms controlling colloid (including microbes and nanoparticles) retention and release on hypothetical porous medium surfaces that exhibit distributions of nanoscale chemical heterogeneity, nano- to microscale roughness, and spati...
NASA Astrophysics Data System (ADS)
Huang, Zhipeng; Gao, Lihong; Wang, Yangwei; Wang, Fuchi
2016-09-01
The Johnson-Cook (J-C) constitutive model is widely used in the finite element simulation, as this model shows the relationship between stress and strain in a simple way. In this paper, a cluster global optimization algorithm is proposed to determine the J-C constitutive model parameters of materials. A set of assumed parameters is used for the accuracy verification of the procedure. The parameters of two materials (401 steel and 823 steel) are determined. Results show that the procedure is reliable and effective. The relative error between the optimized and assumed parameters is no more than 4.02%, and the relative error between the optimized and assumed stress is 0.2% × 10-5. The J-C constitutive parameters can be determined more precisely and quickly than the traditional manual procedure. Furthermore, all the parameters can be simultaneously determined using several curves under different experimental conditions. A strategy is also proposed to accurately determine the constitutive parameters.
Halperin, Israel; Aboodarda, Saied Jalal; Button, Duane C.; Andersen, Lars L.
2014-01-01
Background: Limited dorsiflexion range of motion (ROM) has been linked to lower limb injuries. Improving limited ankle ROM may decrease injury rates. Static stretching (SS) is ubiquitously used to improve ROM but can lead to decreases in force and power if performed prior to the activity. Thus, alternatives to improve ROM without performance decrements are needed. Objectives/Purpose: To compare the effects of SS and self massage (SM) with a roller massage of the calf muscles on ankle ROM, maximal voluntary contraction (MVC) force F100 (force produced in the first 100 ms of the MVC), electromyography (EMG of soleus and tibialis anterior) characteristics of the plantar flexors, and a single limb balance test. Methods: Fourteen recreationally trained subjects were tested on two separate occasions in a randomized cross‐over design. After a warm up, subjects were assessed for passive dorsiflexion ROM, MVC, and a single‐limb balance test with eyes closed. The same three measurements were repeated after 10 minutes (min) of rest and prior to the interventions. Following the pre‐test, participants randomly performed either SS or SM for 3 sets of 30 seconds (s) with 10s of rest between each set. At one and 10 min post‐interventions the participants repeated the three measurements, for a third and fourth cycle of testing. Results: Roller massage increased and SS decreased maximal force output during the post‐test measurements, with a significant difference occurring between the two interventions at 10 min post‐test (p < 0.05, ES = 1.23, 8.2% difference). Both roller massage (p < 0.05, ES = 0.26, ~4%) and SS (p < 0.05, ES = 0.27, ~5.2%) increased ROM immediately and 10 min after the interventions. No significant effects were found for balance or EMG measures. Conclusions: Both interventions improved ankle ROM, but only the self‐massage with a roller massager led to small improvements in MVC force relative to SS at 10 min post‐intervention. These results
Kwak, Dai Soon; Tao, Quang Bang; Todo, Mitsugu; Jeon, Insu
2012-05-01
Knee joint implants developed by western companies have been imported to Korea and used for Korean patients. However, many clinical problems occur in knee joints of Korean patients after total knee joint replacement owing to the geometric mismatch between the western implants and Korean knee joint structures. To solve these problems, a method to determine the representative dimension parameter values of Korean knee joints is introduced to aid in the design of knee joint implants appropriate for Korean patients. Measurements of the dimension parameters of 88 male Korean knee joint subjects were carried out. The distribution of the subjects versus each measured parameter value was investigated. The measured dimension parameter values of each parameter were grouped by suitable intervals called the "size group," and average values of the size groups were calculated. The knee joint subjects were grouped as the "patient group" based on "size group numbers" of each parameter. From the iterative calculations to decrease the errors between the average dimension parameter values of each "patient group" and the dimension parameter values of the subjects, the average dimension parameter values that give less than the error criterion were determined to be the representative dimension parameter values for designing knee joint implants for Korean patients.
Microtubule and cortical forces determine platelet size during vascular platelet production.
Thon, Jonathan N; Macleod, Hannah; Begonja, Antonija Jurak; Zhu, Jie; Lee, Kun-Chun; Mogilner, Alex; Hartwig, John H; Italiano, Joseph E
2012-05-22
Megakaryocytes release large preplatelet intermediates into the sinusoidal blood vessels. Preplatelets convert into barbell-shaped proplatelets in vitro to undergo repeated abscissions that yield circulating platelets. These observations predict the presence of circular-preplatelets and barbell-proplatelets in blood, and two fundamental questions in platelet biology are what are the forces that determine barbell-proplatelet formation, and how is the final platelet size established. Here we provide insights into the terminal mechanisms of platelet production. We quantify circular-preplatelets and barbell-proplatelets in human blood in high-resolution fluorescence images, using a laser scanning cytometry assay. We demonstrate that force constraints resulting from cortical microtubule band diameter and thickness determine barbell-proplatelet formation. Finally, we provide a mathematical model for the preplatelet to barbell conversion. We conclude that platelet size is limited by microtubule bundling, elastic bending, and actin-myosin-spectrin cortex forces.
A test of improved force field parameters for urea: molecular-dynamics simulations of urea crystals.
Özpınar, Gül Altınbaş; Beierlein, Frank R; Peukert, Wolfgang; Zahn, Dirk; Clark, Timothy
2012-08-01
Molecular-dynamics (MD) simulations of urea crystals of different shapes (cubic, rectangular prismatic, and sheet) have been performed using our previously published force field for urea. This force field has been validated by calculating values for the cohesive energy, sublimation temperature, and melting point from the MD data. The cohesive energies computed from simulations of cubic and rectangular prismatic urea crystals in vacuo at 300 K agreed very well with the experimental sublimation enthalpies reported at 298 K. We also found very good agreement between the melting points as observed experimentally and from simulations. Annealing the crystals just below the melting point leads to reconstruction to form crystal faces that are consistent with experimental observations. The simulations reveal a melting mechanism that involves surface (corner/edge) melting well below the melting point, and rotational disordering of the urea molecules in the corner/edge regions of the crystal, which then facilitates the translational motion of these molecules.
Conservative force model performance for TOPEX/Poseidon precision orbit determination
NASA Technical Reports Server (NTRS)
Marshall, J. Andrew; Luthcke, Scott B.
1993-01-01
The TOPEX/Poseidon spacecraft was launched on August 10, 1992 to study the Earth's oceans. To achieve maximum benefit from the altimetric data collected, mission requirements dictate that TOPEX/Poseidon's orbit must be computed at an unprecedented level of accuracy. In order to satisfy these requirements, a model which accounts for the satellite's complex geometry, attitude, and surface properties has been developed. This `box-wing' representation treats the spacecraft as the combination of flat plates arranged in the shape of a box and a connecetd solar array. The nonconservative forces acting on each of the eight surfaces are computed independently, yielding vector accelerations which are summed to compute the total aggregate effect on the satellite center-of-mass. Parameters associated with each flat plate were derived from a finite element analysis of the spacecraft. Certain parameters can be inferred from tracking data and have been adjusted to obtain a better representation of the satellite acceleration history. Changes in the nominal mission profile and the presence of an `anomalistic' force have complicated this tuning process. Model performance, parameter sensitivities, and the `anomalistic' force will be discussed.
NASA Astrophysics Data System (ADS)
Golub, V. P.; Fernati, P. V.; Lyashenko, Ya. G.
2008-09-01
The parameters of the fractional exponential creep and relaxation kernels of linear viscoelastic materials are determined. Methods that approximate the kernel by using the Mittag-Leffler function, the Laplace-Carson transform, and direct approximation of the creep function by the original equation are analyzed. The parameters of fractional exponential kernels are determined for aramid fibers, parapolyamide fibers, glass-reinforced plastic, and polymer concrete. It is shown that the kernel parameters calculated through the direct approximation of the creep function provide the best agreement between theory and experiment. The methods are experimentally validated for constant-stress and variable-stress loading in the modes of additional loading and complete unloading
A new method to determine the partial solubility parameters of polymers from intrinsic viscosity.
Bustamante, Pilar; Navarro-Lupión, Javier; Escalera, Begoña
2005-02-01
A modification of the extended Hansen method, formerly used to determine the partial solubility parameters of drugs and non-polymeric excipients is tested with a polymer for the first time. The proposed method relates the logarithm of the intrinsic viscosities of the polymer in a series of solvents and solvent mixtures with the Hansen (three parameter model) and Karger (four parameter model) partial solubility parameters. The viscosity of diluted solutions of hydroxypropyl methylcellulose (HPMC) was determined in pure solvents and binary mixtures of varying polarity. The intrinsic viscosity was obtained from the common intercept of the Huggins and Kraemer relationships. The intrinsic viscosity tends to increase with increasing the solubility parameter of the medium. The results show that hydrogen bonding and polarity of the polymer largely determine polymer-solvent interactions. The models proposed provided reasonable partial and total solubility parameters for the polymer and enable one to quantitatively characterize, for the first time, the Lewis acid-base ability of a polymer thus, providing a more realistic picture of hydrogen bonding for solvent selection/compatibility and to predict drug-polymer interactions. Combination of the dispersion and polar parameters into a single non-specific solubility parameter was also tested. The results extend earlier findings and suggest that the models are quite versatile and may be applied to drugs, non-polymeric and polymeric excipients.
Parameter determination for singlet oxygen modeling of BPD-mediated PDT
NASA Astrophysics Data System (ADS)
McMillan, Dayton D.; Chen, Daniel; Kim, Michele M.; Liang, Xing; Zhu, Timothy C.
2013-03-01
Photodynamic therapy (PDT) offers a cancer treatment modality capable of providing minimally invasive localized tumor necrosis. To accurately predict PDT treatment outcome based on pre-treatment patient specific parameters, an explicit dosimetry model is used to calculate apparent reacted 1O2 concentration ([1O2]rx) at varied radial distances from the activating light source inserted into tumor tissue and apparent singlet oxygen threshold concentration for necrosis ([1O2]rx, sd) for type-II PDT photosensitizers. Inputs into the model include a number of photosensitizer independent parameters as well as photosensitizer specific photochemical parameters ξ σ, and β. To determine the specific photochemical parameters of benzoporphyrin derivative monoacid A (BPD), mice were treated with BPDPDT with varied light source strengths and treatment times. All photosensitizer independent inputs were assessed pre-treatment and average necrotic radius in treated tissue was determined post-treatment. Using the explicit dosimetry model, BPD specific ξ σ, and β photochemical parameters were determined which estimated necrotic radii similar to those observed in initial BPD-PDT treated mice using an optimization algorithm that minimizes the difference between the model and that of the measurements. Photochemical parameters for BPD are compared with those of other known photosensitizers, such as Photofrin. The determination of these BPD specific photochemical parameters provides necessary data for predictive treatment outcome in clinical BPD-PDT using the explicit dosimetry model.
[Determination of Virtual Surgery Mass Point Spring Model Parameters Based on Genetic Algorithms].
Chen, Ying; Hu, Xuyi; Zhu, Qiguang
2015-12-01
Mass point-spring model is one of the commonly used models in virtual surgery. However, its model parameters have no clear physical meaning, and it is hard to set the parameter conveniently. We, therefore, proposed a method based on genetic algorithm to determine the mass-spring model parameters. Computer-aided tomography (CAT) data were used to determine the mass value of the particle, and stiffness and damping coefficient were obtained by genetic algorithm. We used the difference between the reference deformation and virtual deformation as the fitness function to get the approximate optimal solution of the model parameters. Experimental results showed that this method could obtain an approximate optimal solution of spring parameters with lower cost, and could accurately reproduce the effect of the actual deformation model as well.
Jing, Xufeng; Xia, Rui; Wang, Weimin; Tian, Ying; Hong, Zhi
2016-05-01
We propose analytical expressions to determine the effective constitutive parameters of a planar bianisotropic metamaterial from scattering parameters in the terahertz region. In our retrieval method, the transmission and reflection coefficients in only one wave propagation direction are applied. Considering the nonsymmetry of planar metamaterials in the wave propagation direction, the effective refractive index and the impedance should be obtained by a modified S parameters retrieval process. The effective parameters of the permittivity, permeability, and magnetoelectric coupling coefficient of planar bianisotropic metamaterials can be retrieved by derived equations. Specifically, the constitutive parameters for different planar metamaterials, among which two are isotropic and the other two are bianisotropic metamaterials, are determined. The intrinsic differences between the normal planar metamaterials and the bianisotropic metamaterials are evidently illustrated. The phenomenon including electric coupling to magnetic resonance and only electric response in the transmission spectrum is confirmed by retrieval effective permittivity and permeability.
Margreitter, Christian; Reif, Maria M; Oostenbrink, Chris
2017-04-15
In this study, we propose newly derived parameters for phosphate ions in the context of the GROMOS force field parameter sets. The non-bonded parameters used up to now lead to a hydration free energy, which renders the dihydrogen phosphate ion too hydrophobic when compared to experimentally derived values, making a reparametrization of the phosphate moiety necessary. Phosphate species are of great importance in biomolecular simulations not only because of their crucial role in the backbone of nucleic acids but also as they represent one of the most important types of post-translational modifications to protein side-chains and are an integral part in many lipids. Our re-parametrization of the free dihydrogen phosphate (H 2PO 4-) and three derivatives (methyl phosphate, dimethyl phosphate, and phenyl phosphate) leads, in conjunction with the previously updated charged side-chains in the GROMOS parameter set 54A8, to new nucleic acid backbone parameters and a 54A8 version of the widely used GROMOS protein post-translational modification parameter set. © 2017 Wiley Periodicals, Inc.
GNSS orbit determination by precise modeling of non-gravitational forces acting on satellite's body
NASA Astrophysics Data System (ADS)
Wielgosz, Agata; Kalarus, Maciej; Liwosz, Tomasz
2016-04-01
Satellites orbiting around Earth are affected by gravitational forces and non-gravitational perturbations (NGP). While the perturbations caused by gravitational forces, which are due to central body gravity (including high-precision geopotential field) and its changes (due to secular variations and tides), solar bodies attraction and relativistic effects are well-modeled, the perturbations caused by the non-gravitational forces are the most limiting factor in Precise Orbit Determination (POD). In this work we focused on very precise non-gravitational force modeling for medium Earth orbit satellites by applying the various models of solar radiation pressure including changes in solar irradiance and Earth/Moon shadow transition, Earth albedo and thermal radiation. For computing influence of aforementioned forces on spacecraft the analytical box-wing satellite model was applied. Smaller effects like antenna thrust or spacecraft thermal radiation were also included. In the process of orbit determination we compared the orbit with analytically computed NGP with the standard procedure in which CODE model is fitted for NGP recovery. We considered satellites from several systems and on different orbits and for different periods: when the satellite is all the time in full sunlight and when transits the umbra and penumbra regions.
NASA Astrophysics Data System (ADS)
Nakayama, Masaki; Katano, Hiroaki; Sato, Haruki
2014-05-01
A precise determination of the critical temperature and density for technically important fluids would be possible on the basis of the digital image for the visual observation of the phase boundary in the vicinity of the critical point since the sensitivity and resolution are higher than those of naked eyes. In addition, the digital image can avoid the personal uncertainty of an observer. A strong density gradient occurs in a sample cell at the critical point due to gravity. It was carefully assessed to determine the critical density, where the density profile in the sample cell can be observed from the luminance profile of a digital image. The density-gradient profile becomes symmetric at the critical point. One of the best fluids, whose thermodynamic properties have been measured with the highest reliability among technically important fluids, would be carbon dioxide. In order to confirm the reliability of the proposed method, the critical temperature and density of carbon dioxide were determined using the digital image. The critical temperature and density values of carbon dioxide are ( and ( kg m, respectively. The critical temperature and density values agree with the existing best values within estimated uncertainties. The reliability of the method was confirmed. The critical pressure, 7.3795 MPa, corresponding to the determined critical temperature of 304.143 K is also proposed. A new set of parameters for the vapor-pressure equation is also provided.
Nagel, Tina M; Hadi, Mohammad F; Claeson, Amy A; Nuckley, David J; Barocas, Victor H
2014-11-01
Performing planar biaxial testing and using nominal stress-strain curves for soft-tissue characterization is most suitable when (1) the test produces homogeneous strain fields, (2) fibers are aligned with the coordinate axes, and (3) strains are measured far from boundaries. Some tissue types [such as lamellae of the annulus fibrosus (AF)] may not allow for these conditions to be met due to their natural geometry and constitution. The objective of this work was to develop and test a method utilizing a surface displacement field, grip force-stretch data, and finite-element (FE) modeling to facilitate analysis of such complex samples. We evaluated the method by regressing a simple structural model to simulated and experimental data. Three different tissues with different characteristics were used: Superficial pectoralis major (SPM) (anisotropic, aligned with axes), facet capsular ligament (FCL) (anisotropic, aligned with axes, bone attached), and a lamella from the AF (anisotropic, aligned off-axis, bone attached). We found that the surface displacement field or the grip force-stretch data information alone is insufficient to determine a unique parameter set. Utilizing both data types provided tight confidence regions (CRs) of the regressed parameters and low parameter sensitivity to initial guess. This combined fitting approach provided robust characterization of tissues with varying fiber orientations and boundaries and is applicable to tissues that are poorly suited to standard biaxial testing. The structural model, a set of C++ finite-element routines, and a Matlab routine to do the fitting based on a set of force/displacement data is provided in the on-line supplementary material.
Influence of sub-Doppler force on the Doppler trap parameters of a magneto-optical trap
NASA Astrophysics Data System (ADS)
Noh, Heung-Ryoul; Kim, Kihwan
2005-05-01
We have measured the trap frequency as well as the damping coefficient of a magneto-optical trap by using a transient oscillation method. The dependence of such trap properties on the various experimental parameters such as the cooling laser intensity, detuning, and magnetic field gradient is investigated. We find that the measured trap frequency is in excellent agreement with the simple rate-equation analysis based on the Doppler cooling theory. In contrast, the damping coefficient is about twice larger than the calculated one, which is attributed to the existence of the sub-Doppler trap near the trap center. We also have shown for the multi-level atom the trap parameters are affected by the laser intensity, detuning of other directions. From the measurement of the damping coefficient, we have found that the trap parameters are affected by the sub-Doppler force. These observations are explained by the direct calculation of the force where the detuning of transverse laser is different from the considered axis.
Federal Register 2010, 2011, 2012, 2013, 2014
2012-11-06
... Under Secretary of the Air Force (Space). ACTION: Publicize Consent Order, and Determine Level of... Deputy Under Secretary of the Air Force (Space), as the Compliance Officer under the Federal Trade... current Compliance Officer is the Deputy Under Secretary of the Air Force (Space), Mr. Richard...
Code of Federal Regulations, 2011 CFR
2011-07-01
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Code of Federal Regulations, 2010 CFR
2010-07-01
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Code of Federal Regulations, 2014 CFR
2014-07-01
... connection for former members of the Armed Forces of Czechoslovakia or Poland. 3.359 Section 3.359 Pensions... connection for former members of the Armed Forces of Czechoslovakia or Poland. Rating boards will determine whether or not the condition for which treatment is claimed by former members of the Armed Forces...
Code of Federal Regulations, 2012 CFR
2012-07-01
... connection for former members of the Armed Forces of Czechoslovakia or Poland. 3.359 Section 3.359 Pensions... connection for former members of the Armed Forces of Czechoslovakia or Poland. Rating boards will determine whether or not the condition for which treatment is claimed by former members of the Armed Forces...
Code of Federal Regulations, 2013 CFR
2013-07-01
... connection for former members of the Armed Forces of Czechoslovakia or Poland. 3.359 Section 3.359 Pensions... connection for former members of the Armed Forces of Czechoslovakia or Poland. Rating boards will determine whether or not the condition for which treatment is claimed by former members of the Armed Forces...
Effects of wing modification on an aircraft's aerodynamic parameters as determined from flight data
NASA Technical Reports Server (NTRS)
Hess, R. A.
1986-01-01
A study of the effects of four wing-leading-edge modifications on a general aviation aircraft's stability and control parameters is presented. Flight data from the basic aircraft configuration and configurations with wing modifications are analyzed to determine each wing geometry's stability and control parameters. The parameter estimates and aerodynamic model forms are obtained using the stepwise regression and maximum likelihood techniques. The resulting parameter estimates and aerodynamic models are verified using vortex-lattice theory and by analysis of each model's ability to predict aircraft behavior. Comparisons of the stability and control derivative estimates from the basic wing and the four leading-edge modifications are accomplished so that the effects of each modification on aircraft stability and control derivatives can be determined.
NASA Astrophysics Data System (ADS)
Godinez, Humberto C.; Reisner, Jon M.; Fierro, Alexandre O.; Guimond, Stephen R.; Kao, Jim
2012-11-01
In this work we determine key model parameters for rapidly intensifying Hurricane Guillermo (1997) using the Ensemble Kalman Filter (EnKF). The approach is to utilize the EnKF as a tool to only estimate the parameter values of the model for a particular data set. The assimilation is performed using dual-Doppler radar observations obtained during the period of rapid intensification of Hurricane Guillermo. A unique aspect of Guillermo was that during the period of radar observations strong convective bursts, attributable to wind shear, formed primarily within the eastern semicircle of the eyewall. To reproduce this observed structure within a hurricane model, background wind shear of some magnitude must be specified; as well as turbulence and surface parameters appropriately specified so that the impact of the shear on the simulated hurricane vortex can be realized. To identify the complex nonlinear interactions induced by changes in these parameters, an ensemble of model simulations have been conducted in which individual members were formulated by sampling the parameters within a certain range via a Latin hypercube approach. The ensemble and the data, derived latent heat and horizontal winds from the dual-Doppler radar observations, are utilized in the EnKF to obtain varying estimates of the model parameters. The parameters are estimated at each time instance, and a final parameter value is obtained by computing the average over time. Individual simulations were conducted using the estimates, with the simulation using latent heat parameter estimates producing the lowest overall model forecast error.
NASA Technical Reports Server (NTRS)
Hawkins, Richard; Penland, Jim A.
1997-01-01
Observations have been made and reported that the experimental normal force coefficients at a constant angle of attack were constant with a variation of more than 2 orders of magnitude of Reynolds number at a free-stream Mach number M(sub infinity) of 8.00 and more than 1 order of magnitude variation at M(sub infinity) = 6.00 on the same body-wing hypersonic cruise configuration. These data were recorded under laminar, transitional, and turbulent boundary layer conditions with both hot-wall and cold-wall models. This report presents experimental data on 25 configurations of 17 models of both simple and complex geometry taken at M(sub infinity) = 6.00, 6.86, and 8.00 in 4 different hypersonic facilities. Aerodynamic calculations were made by computational fluid dynamics (CID) and engineering methods to analyze these data. The conclusions were that the normal force coefficients at a given altitude are constant with Reynolds numbers at hypersonic speeds and that the axial force coefficients recorded under laminar boundary-layer conditions at several Reynolds numbers may be plotted against the laminar parameter (the reciprocal of the Reynolds number to the one-half power) and extrapolated to the ordinate axis to determine the inviscid-wave-drag coefficient at the intercept.
Zhou, Y.; Ojeda-May, P.; Nagaraju, M.; Pu, J.
2016-01-01
Adenosine triphosphate (ATP)-binding cassette (ABC) transporters are ubiquitous ATP-dependent membrane proteins involved in translocations of a wide variety of substrates across cellular membranes. To understand the chemomechanical coupling mechanism as well as functional asymmetry in these systems, a quantitative description of how ABC transporters hydrolyze ATP is needed. Complementary to experimental approaches, computer simulations based on combined quantum mechanical and molecular mechanical (QM/MM) potentials have provided new insights into the catalytic mechanism in ABC transporters. Quantitatively reliable determination of the free energy requirement for enzymatic ATP hydrolysis, however, requires substantial statistical sampling on QM/MM potential. A case study shows that brute force sampling of ab initio QM/MM (AI/MM) potential energy surfaces is computationally impractical for enzyme simulations of ABC transporters. On the other hand, existing semiempirical QM/MM (SE/MM) methods, although affordable for free energy sampling, are unreliable for studying ATP hydrolysis. To close this gap, a multiscale QM/MM approach named reaction path–force matching (RP–FM) has been developed. In RP–FM, specific reaction parameters for a selected SE method are optimized against AI reference data along reaction paths by employing the force matching technique. The feasibility of the method is demonstrated for a proton transfer reaction in the gas phase and in solution. The RP–FM method may offer a general tool for simulating complex enzyme systems such as ABC transporters. PMID:27498639
Determination of Structural Parameters of Thin-Film Photocatalytic Materials by BDS
NASA Astrophysics Data System (ADS)
Korte, Dorota; Franko, Mladen
2015-09-01
A method for determination of structural parameters of some thin-film photocatalytic materials is presented. The analysis was based on the material's thermal parameter dependences on its surface structure or porosity and was thus performed by the use of beam deflection spectroscopy (BDS) supported by theoretical analysis made in the framework of complex geometrical optics. The results obtained by BDS were than compared with those received on the basis of AFM and SEM measurements and found to be in good agreement.
Nikiforidis, G; Tsambaos, D; Balas, C; Bezerianos, A
1993-01-01
An analytical model and the corresponding experimental procedure are presented, which make it possible to separately analyze the viscous and elastic components of human hair. Moreover, a computerized experimental system is described with which a standardized quantitative determination of the most important mechanical parameters of human hair can be performed. Comparative investigations of the mechanical behavior of hair specimens obtained from the frontoparietal and occipital scalp regions of 10 healthy human subjects showed no statistically significant differences with regard to their mechanical parameters. Nevertheless, the paired analysis of the mechanical parameters of thin and thick hair specimens revealed that the values of two of these parameters are significantly higher in thin than in thick hair specimens. These findings suggest that there are mechanical parameters of human hair related to gross hair morphology, whereas others depend on hair microstructure.
Nakamura, Hideya; Sugino, Yui; Watano, Satoru
2012-01-01
A novel in-die evaluation method of tablet capping tendency was proposed based on a force-displacement curve and stress relaxation parameter in a tableting process. In our previous study (Chem. Pharm. Bull., 59, 2011, Nakamura et al.), the phase diagram consisting of elastic recovery energy (E(e)) and plastic deformation energy (E(p)) of compressed powder, named as the E(e)-E(p) diagram, was proposed. However, it was found that capping tendency of tablets prepared by double-compression with multi-component powder formulations cannot be discriminated using the E(e)-E(p) diagram. To improve the capping discrimination ability, we here proposed a novel corrected phase diagram consisting of the E(e) and an interparticle bonding parameter E(b)(t), named as the E(e)-E(b)(t) diagram. The E(b)(t) was proposed as a new parameter expressing strength of the interparticle bonding formed by the stress relaxation inside compressed powder. The E(b)(t) was defined as a product of the E(p) and the stress relaxation parameter Y(t), estimated from the force-displacement curve and the stress relaxation test. The capping discrimination ability of the diagrams was evaluated using a hierarchical-clustering analysis. The results exhibited that the capping tendency could be clearly discriminated using the proposed E(e)-E(b)(t) diagram at the double-compression and the multi-component powder formulations, as compared to the E(e)-E(p) diagram. This proposed diagram can be used for screening of the powder formulations to avoid the capping.
Blumrosen, Gadi; Abazari, Alireza; Golberg, Alexander; Yarmush, Martin L; Toner, Mehmet
2016-09-01
The design of effective electroporation protocols for molecular delivery applications requires the determination of transport parameters including diffusion coefficient, membrane resealing, and critical electric field strength for electroporation. The use of existing technologies to determine these parameters is time-consuming and labor-intensive, and often results in large inconsistencies in parameter estimation due to variations in the protocols and setups. In this work, we suggest using a set of concentric electrodes to screen a full range of electric field strengths in a single test to determine the electroporation-induced transmembrane transport parameters. Using Calcein as a fluorescent probe, we developed analytical methodology to determine the transport parameters based on the electroporation-induced pattern of fluorescence loss from cells. A monolayer of normal human dermal fibroblast (NHDF) cells were pre-loaded with Calcein and electroporated with an applied voltage of 750V with 10 and 50 square pulses with 50μs duration. Using our analytical model, the critical electric field strength for electroporation was found for the 10 and 50 pulses experiments. An inverse correlation between the field strength and the molecular transport time decay constant, and a direct correlation between field strength and the membrane permeability were observed. The results of this work can simplify the development of electroporation-assisted technologies for research and therapies.
Code of Federal Regulations, 2010 CFR
2010-07-01
... member, the member is constructed of a material which when bent would return to its original shape after the force is removed (plastic or spring steel materials); (D) In the case of any parameter, the... forces or torques applied to the adjustment; (C) The manufacturer demonstrates that travel or...
NASA Astrophysics Data System (ADS)
Golub, V. P.; Ragulina, V. S.; Fernati, P. V.
2015-03-01
A method for determining the parameters of the hereditary kernels for nonlinear viscoelastic materials is tested in conditions of pure torsion. A Rabotnov-type model is chosen. The parameters of the hereditary kernels are determined by fitting discrete values of the kernels found using a similarity condition. The discrete values of the kernels in the zone of singularity occurring in short-term tests are found using weight functions. The Abel kernel, a combination of power and exponential functions, and a fractional-exponential function are considered
The application of virtual prototyping methods to determine the dynamic parameters of mobile robot
NASA Astrophysics Data System (ADS)
Kurc, Krzysztof; Szybicki, Dariusz; Burghardt, Andrzej; Muszyńska, Magdalena
2016-04-01
The paper presents methods used to determine the parameters necessary to build a mathematical model of an underwater robot with a crawler drive. The parameters present in the dynamics equation will be determined by means of advanced mechatronic design tools, including: CAD/CAE software andMES modules. The virtual prototyping process is described as well as the various possible uses (design adaptability) depending on the optional accessories added to the vehicle. A mathematical model is presented to show the kinematics and dynamics of the underwater crawler robot, essential for the design stage.
NASA Astrophysics Data System (ADS)
Clement, R.; Reglero, V.; Garcia, M.; Fabregat, J.; Bravo, A.; Suso, J.
1993-01-01
A new uvby and H-beta monitoring program of low mass eclipsing binaries is currently being carried out in the framework of a 5-yr observational program which also involves radial velocity determinations. The scope of this work is to provide very accurate absolute astrophysical parameters: mass, radius, and effective temperatures, for main-sequence late-type stars. One of the main goals is to improve the mass-luminosity relation in the low and intermediate mass range. A second objective is to perform accurate tests of the most recent grids of evolutionary models. This program is complementary to that currently being implemented by the Copenhagen group. In this contribution we present the photometric preliminary results obtained for three of the systems included in our long-term survey: BH Vir, ZZ UMa, and CR Cas for which primary eclipses have been observed. Particular attention is paid to the determination of reddening, distances, and radiative properties. A more detailed study will be carried out when the light curves and radial velocity measurements are completed.
Determining an Appropriate Force Sizing Paradigm for the U.S. Army
2006-05-31
USAWC STRATEGY RESEARCH PROJECT DETERMINING AN APPROPRIATE FORCE SIZING PARADIGM FOR THE U.S. ARMY by Lieutenant Colonel Ricky D. Gibbs United States...Army Colonel David Brooks Project Advisor The views expressed in this academic research paper are those of the This SRP is submitted in partial...fulfillment of the requirements of the Master of Strategic Studies Degree. The views expressed in this student academic research paper are those of the
Determination of parameter identifiability in nonlinear biophysical models: A Bayesian approach
Hines, Keegan E.; Middendorf, Thomas R.
2014-01-01
A major goal of biophysics is to understand the physical mechanisms of biological molecules and systems. Mechanistic models are evaluated based on their ability to explain carefully controlled experiments. By fitting models to data, biophysical parameters that cannot be measured directly can be estimated from experimentation. However, it might be the case that many different combinations of model parameters can explain the observations equally well. In these cases, the model parameters are not identifiable: the experimentation has not provided sufficient constraining power to enable unique estimation of their true values. We demonstrate that this pitfall is present even in simple biophysical models. We investigate the underlying causes of parameter non-identifiability and discuss straightforward methods for determining when parameters of simple models can be inferred accurately. However, for models of even modest complexity, more general tools are required to diagnose parameter non-identifiability. We present a method based in Bayesian inference that can be used to establish the reliability of parameter estimates, as well as yield accurate quantification of parameter confidence. PMID:24516188
Weerachanchai, Piyarat; Wong, Yuewen; Lim, Kok Hwa; Tan, Timothy Thatt Yang; Lee, Jong-Min
2014-11-10
The total and partial solubility parameters (dispersion, polar and hydrogen-bonding solubility parameters) of ten ionic liquids were determined. Intrinsic viscosity approaches were used that encompassed a one-dimensional method (1D-Method), and two different three-dimensional methods (3D-Method1 and 3D-Method2). The effect of solvent type, the dimethylacetamide (DMA) fraction in the ionic liquid, and dissolution temperature on solubility parameters were also investigated. For all types of effect, both the 1D-Method and 3D-Method2 present the same trend in the total solubility parameter. The partial solubility parameters are influenced by the cation and anion of the ionic liquid. Considering the effect on partial solubility parameters of the solvent type in the ionic liquid, it was observed that in both 3D methods, the dispersion and polar parameters of a 1-ethyl-3-methylimidazolium acetate/solvent (60:40 vol %) mixture tend to increase as the total solubility parameter of the solvent increases.
Determination of power system component parameters using nonlinear dead beat estimation method
NASA Astrophysics Data System (ADS)
Kolluru, Lakshmi
Power systems are considered the most complex man-made wonders in existence today. In order to effectively supply the ever increasing demands of the consumers, power systems are required to remain stable at all times. Stability and monitoring of these complex systems are achieved by strategically placed computerized control centers. State and parameter estimation is an integral part of these facilities, as they deal with identifying the unknown states and/or parameters of the systems. Advancements in measurement technologies and the introduction of phasor measurement units (PMU) provide detailed and dynamic information of all measurements. Accurate availability of dynamic measurements provides engineers the opportunity to expand and explore various possibilities in power system dynamic analysis/control. This thesis discusses the development of a parameter determination algorithm for nonlinear power systems, using dynamic data obtained from local measurements. The proposed algorithm was developed by observing the dead beat estimator used in state space estimation of linear systems. The dead beat estimator is considered to be very effective as it is capable of obtaining the required results in a fixed number of steps. The number of steps required is related to the order of the system and the number of parameters to be estimated. The proposed algorithm uses the idea of dead beat estimator and nonlinear finite difference methods to create an algorithm which is user friendly and can determine the parameters fairly accurately and effectively. The proposed algorithm is based on a deterministic approach, which uses dynamic data and mathematical models of power system components to determine the unknown parameters. The effectiveness of the algorithm is tested by implementing it to identify the unknown parameters of a synchronous machine. MATLAB environment is used to create three test cases for dynamic analysis of the system with assumed known parameters. Faults are
Radiative force model performance for TOPEX/Poseidon precision orbit determination
NASA Technical Reports Server (NTRS)
Marshall, J. Andrew; Luthcke, Scott B.
1994-01-01
The TOPEX/Poseidon spacecraft was launched to study the Earth's oceans. To maximize the benefit from the alimetric data collected, mission requirements dictate that TOPEX/Poseidon's orbit must be computed at extremely high accuracy. To meet these demands, a nonconservative force model which accounts for the satellite's complex geometry, attitude and surface properties has been developed. The 'box-wing' representation treats the spacecraft as the combination of flat plates arranged in the shape of a box and a connected solar array. Model performance and parameter sensitivities are discussed.
A Study of Parameters Affecting Fibroblast Morphology in Response to an Applied Mechanical Force
NASA Technical Reports Server (NTRS)
Grymes, Rosalind A.; Sawyer, Christine
1994-01-01
A precisely controlled stretch/relaxation regimen (20% elongation at 6.6 cycles/min) was applied to normal human fetal, neonatal and aged dermal fibroblasts cultured on flexible membranes. Culture conditions included poly (NH2) or collagen type I coated substrate membranes; control cultures were grown on the same pliable material in the absence of applied stretch. Direct observation and immunofluorescence analyses revealed a progressive change in cell body orientation limited to the stretched dermal fibroblast cultures. Monolayers gradually (over 4 days) acquired a symmetric, radial distribution equivalent to the biaxial array of the applied force. At high seeding density, alignment was inhibited in the fetal cell cultures. This cell strain required collagen type I coating for optimal attachment to the flexible membrane, preferring growth in three-dimensional cell 'balls' on the poly(NH2) coated substrate. Neonatal cells also required the collagen type I coating, but both neonatal and aged dermal fibroblasts aligned efficiently at all seeding densities examined. The randomly oriented neonatal cells on the unstretched control membranes spontaneously detached at confluence, as a single cell sheet. Their aligned counterparts did not detach until the applied stretch stimulus was removed. Low concentrations of cytochalasin D (62.5 ng/ml) disrupted the stretch-related alignment response. Rhodamine phalloidin staining visualized fewer actin stress fibers in stretched, aligned cells than in controls. Both intercellular interactions and cytoskeletal integrity mediate the response to mechanical strain. Normal rabbit corneal stroma fibroblasts (NRC) were also analyzed, and failed to orient under these conditions. This cell type may require a different regimen, or a longer time period, to demonstrate alignment behavior. Supported by NASA Space Biology RTOP 199-40-22 and the NASA-ARC Director's Discretionary Fund.
On the entrainment coefficient in a forced plume: quantitative effects of source parameters
NASA Astrophysics Data System (ADS)
Matulka, A.; López, P.; Redondo, J. M.; Tarquis, A.
2014-02-01
The behavior of a forced plume is mainly controlled by the source buoyancy and momentum fluxes and the efficiency of turbulent mixing between the plume and the ambient fluid (stratified or not). The interaction between the plume and the ambient fluid controls the plume dynamics and is usually represented by the entrainment coefficient αE. Commonly used one-dimensional models incorporating a constant entrainment coefficient are fundamental and very useful for predictions in geophysical flows and industrial situations. Nevertheless, if the basic geometry of the flow changes, or the type of source or the environmental fluid conditions (e.g., level of turbulence, shear, ambient stratification, presence of internal waves), new models allowing for variable entrainment are necessary. The presented paper is an experimental study based on a set of turbulent plume experiments in a calm unstratified ambient fluid under different source conditions (represented by different buoyancy and momentum fluxes). The main result is that the entrainment coefficient is not a constant and clearly varies in time within the same plume independently of the buoyancy and the source position. This paper also analyzes the influence of the source conditions on the mentioned time evolution. The measured entrainment coefficient αE has considerable variability. It ranges between 0.26 and 0.9 for variable Atwood number experiments and between 0.16 and 0.55 for variable source position experiments. As is observed, values are greater than the traditional standard value of Morton et al. (1956) for plumes and jets, which is about 0.13.
Suomi, Visa; Han, Yang; Konofagou, Elisa; Cleveland, Robin O
2016-10-21
Multiple ultrasound elastography techniques rely on acoustic radiation force (ARF) in monitoring high-intensity focused ultrasound (HIFU) therapy. However, ARF is dependent on tissue attenuation and sound speed, both of which are also known to change with temperature making the therapy monitoring more challenging. Furthermore, the viscoelastic properties of tissue are also temperature dependent, which affects the displacements induced by ARF. The aim of this study is to quantify the temperature dependent changes in the acoustic and viscoelastic properties of liver and investigate their effect on ARF induced displacements by using both experimental methods and simulations. Furthermore, the temperature dependent viscoelastic properties of liver are experimentally measured over a frequency range of 0.1-200 Hz at temperatures reaching 80 °C, and both conventional and fractional Zener models are used to fit the data. The fractional Zener model was found to fit better with the experimental viscoelasticity data with respect to the conventional model with up to two orders of magnitude lower sum of squared errors (SSE). The characteristics of experimental displacement data were also seen in the simulations due to the changes in attenuation coefficient and lesion development. At low temperatures before thermal ablation, attenuation was found to affect the displacement amplitude. At higher temperature, the decrease in displacement amplitude occurs approximately at 60-70 °C due to the combined effect of viscoelasticity changes and lesion growth overpowering the effect of attenuation. The results suggest that it is necessary to monitor displacement continuously during HIFU therapy in order to ascertain when ablation occurs.
NASA Astrophysics Data System (ADS)
Suomi, Visa; Han, Yang; Konofagou, Elisa; Cleveland, Robin O.
2016-10-01
Multiple ultrasound elastography techniques rely on acoustic radiation force (ARF) in monitoring high-intensity focused ultrasound (HIFU) therapy. However, ARF is dependent on tissue attenuation and sound speed, both of which are also known to change with temperature making the therapy monitoring more challenging. Furthermore, the viscoelastic properties of tissue are also temperature dependent, which affects the displacements induced by ARF. The aim of this study is to quantify the temperature dependent changes in the acoustic and viscoelastic properties of liver and investigate their effect on ARF induced displacements by using both experimental methods and simulations. Furthermore, the temperature dependent viscoelastic properties of liver are experimentally measured over a frequency range of 0.1-200 Hz at temperatures reaching 80 °C, and both conventional and fractional Zener models are used to fit the data. The fractional Zener model was found to fit better with the experimental viscoelasticity data with respect to the conventional model with up to two orders of magnitude lower sum of squared errors (SSE). The characteristics of experimental displacement data were also seen in the simulations due to the changes in attenuation coefficient and lesion development. At low temperatures before thermal ablation, attenuation was found to affect the displacement amplitude. At higher temperature, the decrease in displacement amplitude occurs approximately at 60-70 °C due to the combined effect of viscoelasticity changes and lesion growth overpowering the effect of attenuation. The results suggest that it is necessary to monitor displacement continuously during HIFU therapy in order to ascertain when ablation occurs.
Determination of the force transmitted by an ion thruster plasma plume to an orbital object
NASA Astrophysics Data System (ADS)
Alpatov, A.; Cichocki, F.; Fokov, A.; Khoroshylov, S.; Merino, M.; Zakrzhevskii, A.
2016-02-01
An approach to determine the force transmitted by the plasma plume of an ion thruster to an orbital object immersed in it using its central projection on a selected plane is proposed. A photo camera is used to obtain the image of the object central projection. The algorithms for the calculation of the transmission of momentum by the impacting ion beam are developed including the determination of the object contour and the correction of the error due to a camera offset from the ion beam axis, and the computation of the fraction of the ion beam that impinges on the object surface.
NASA Astrophysics Data System (ADS)
Brunel, David; Deresmes, Dominique; Mélin, Thierry
2009-06-01
We use Kelvin force microscopy (KFM) to study the electrostatic properties of single-walled carbon nanotube field effect transistor devices (CNTFETs) with backgate geometry at room temperature. We show that KFM maps recorded as a function of the device backgate polarization enable a complete phenomenological determination of the averaging effects associated with the KFM probe side capacitances, and thus, to obtain KFM measurements with quantitative character. The value of the electrostatic lever arm of the CNTFET is determined from KFM measurements and found in agreement with transport measurements based on Coulomb blockade.
Improvement of the precision of lattice parameter determination by nano-beam electron diffraction.
Saitoh, Koh; Nakahara, Hirotaka; Tanaka, Nobuo
2013-01-01
A highly precise determination of lattice parameters using higher-order Laue zone (HOLZ) reflections observed in nano-beam electron diffraction is presented. The introduction of more than 40 HOLZ reflections, whose positions are corrected by considering the aberration of the electron optics and are determined with an accuracy of 0.04 nm⁻¹, allows us to achieve a remarkable high precision of a 0.02% error, which is four times higher than the precision without HOLZ reflections.
Determining Relative Importance and Effective Settings for Genetic Algorithm Control Parameters.
Mills, K L; Filliben, J J; Haines, A L
2015-01-01
Setting the control parameters of a genetic algorithm to obtain good results is a long-standing problem. We define an experiment design and analysis method to determine relative importance and effective settings for control parameters of any evolutionary algorithm, and we apply this method to a classic binary-encoded genetic algorithm (GA). Subsequently, as reported elsewhere, we applied the GA, with the control parameter settings determined here, to steer a population of cloud-computing simulators toward behaviors that reveal degraded performance and system collapse. GA-steered simulators could serve as a design tool, empowering system engineers to identify and mitigate low-probability, costly failure scenarios. In the existing GA literature, we uncovered conflicting opinions and evidence regarding key GA control parameters and effective settings to adopt. Consequently, we designed and executed an experiment to determine relative importance and effective settings for seven GA control parameters, when applied across a set of numerical optimization problems drawn from the literature. This paper describes our experiment design, analysis, and results. We found that crossover most significantly influenced GA success, followed by mutation rate and population size and then by rerandomization point and elite selection. Selection method and the precision used within the chromosome to represent numerical values had least influence. Our findings are robust over 60 numerical optimization problems.
Determination of the QCD Λ Parameter and the Accuracy of Perturbation Theory at High Energies.
Dalla Brida, Mattia; Fritzsch, Patrick; Korzec, Tomasz; Ramos, Alberto; Sint, Stefan; Sommer, Rainer
2016-10-28
We discuss the determination of the strong coupling α_{MS[over ¯]}(m_{Z}) or, equivalently, the QCD Λ parameter. Its determination requires the use of perturbation theory in α_{s}(μ) in some scheme s and at some energy scale μ. The higher the scale μ, the more accurate perturbation theory becomes, owing to asymptotic freedom. As one step in our computation of the Λ parameter in three-flavor QCD, we perform lattice computations in a scheme that allows us to nonperturbatively reach very high energies, corresponding to α_{s}=0.1 and below. We find that (continuum) perturbation theory is very accurate there, yielding a 3% error in the Λ parameter, while data around α_{s}≈0.2 are clearly insufficient to quote such a precision. It is important to realize that these findings are expected to be generic, as our scheme has advantageous properties regarding the applicability of perturbation theory.
Determination of Some Parameters for Fatigue Life in Welded Joints Using Fracture Mechanics Method
NASA Astrophysics Data System (ADS)
Al-Mukhtar, A. M.; Biermann, H.; Hübner, P.; Henkel, S.
2010-12-01
In this work, the parameters stress intensity factor (SIF), initial and final crack lengths ( a i and a f), crack growth parameters ( C and m), and fatigue strength (FAT) are investigated. The determination of initial crack length seems to be the most serious factor in fatigue life and strength calculations for welded joints. A fracture mechanics approach was used in these calculations based on SIF which was calculated with the finite element method (FEM). The weld toe crack was determined to be equal to 0.1 mm, whereas the weld root crack's length was varied depending on the degree of the weld penetration. These initial crack length values are applicable for all types of joints which have the same crack phenomenon. As based on the above calculated parameters, the new limits of FAT for new geometries which are not listed yet in recommendations can be calculated according to the current approach.
NASA Technical Reports Server (NTRS)
Wu, Jiun-Tsong; Wu, Sien-Chong
1992-01-01
A method to determine satellite orbits using tracking data and a priori gravitational field is described. The a priori constraint on the orbit dynamics is determined by the covariance matrix of the spherical harmonic coefficients for the gravity model, so that the optimal combination of the measurements and gravitational field is achieved. A set of bin parameters is introduced to represent the perturbation of the gravitational field on the position of the satellite orbit. The covariance matrix of a conventional gravity model is transformed into that for the bin parameters by the variational partial derivatives. The covariance matrices of the bin parameters and the epoch state are combined to form the covariance matrix of the satellite positions at the measurement times. The combined matrix is used as the a priori information to estimate the satellite positions with measurements.
The lattice parameter of the 28Si spheres in the determination of the Avogadro constant
NASA Astrophysics Data System (ADS)
Massa, E.; Mana, G.; Ferroglio, L.; Kessler, E. G.; Schiel, D.; Zakel, S.
2011-04-01
The Avogadro constant has been determined by atom counting in two enriched 28Si spheres. Atoms were counted by exploiting their ordered arrangement in the spheres and calculating the ratio between sphere and the unit-cell volumes. This paper describes how the values of the sphere lattice parameters and, consequently, their unit-cell volumes were obtained.
ERIC Educational Resources Information Center
National Bureau of Standards (DOC), Washington, DC.
The system for determining parameters of a particle described in this document is a government-owned invention that is available for licensing. The background of the invention is outlined, and drawings of the system together with a detailed description of its function are provided. A collector contains a hole and annular apertures for transmitting…
Determination of modeling parameters for power IGBTs under pulsed power conditions
Dale, Gregory E; Van Gordon, Jim A; Kovaleski, Scott D
2010-01-01
While the power insulated gate bipolar transistor (IGRT) is used in many applications, it is not well characterized under pulsed power conditions. This makes the IGBT difficult to model for solid state pulsed power applications. The Oziemkiewicz implementation of the Hefner model is utilized to simulate IGBTs in some circuit simulation software packages. However, the seventeen parameters necessary for the Oziemkiewicz implementation must be known for the conditions under which the device will be operating. Using both experimental and simulated data with a least squares curve fitting technique, the parameters necessary to model a given IGBT can be determined. This paper presents two sets of these seventeen parameters that correspond to two different models of power IGBTs. Specifically, these parameters correspond to voltages up to 3.5 kV, currents up to 750 A, and pulse widths up to 10 {micro}s. Additionally, comparisons of the experimental and simulated data will be presented.
Determination of partial solubility parameters of five benzodiazepines in individual solvents.
Verheyen, S; Augustijns, P; Kinget, R; Van den Mooter, G
2001-10-09
Three and four component partial solubility parameters for diazepam, lorazepam, oxazepam, prazepam and temazepam were determined using the extended and expanded Hansen regression models. A comparison was made also with solubility parameters calculated by the group contribution method proposed by Van Krevelen. Although a limited number of solvents was used, the results from the present study indicate that the partial solubility parameters obtained from the experimental regression models clearly reflect the structural differences in these five structurally related molecules. High R(2)-values were observed in the regression models (0.932 < or =R(2)< or =0.984), except for lorazepam (0.606 < or =R(2)< or =0.825). This was attributed to difficulties in obtaining reliable values of the temperature and heat of fusion due to thermal decomposition of this compound. Introduction of the Flory-Huggins size correction parameter did not improve the R(2)- and F-values in any of the regression models used.
Determination of discharge parameters via OES at the Linac4 H- ion source
NASA Astrophysics Data System (ADS)
Briefi, S.; Fink, D.; Mattei, S.; Lettry, J.; Fantz, U.
2016-02-01
Optical emission spectroscopy (OES) measurements of the atomic Balmer series and the molecular Fulcher transition have been carried out at the Linac4 ion source in order to determine plasma parameters. As the spectroscopic system was only relatively calibrated, the data evaluation only yielded rough estimates of the plasma parameters (Te ≈ 1.2 eV, ne ≈ 1 × 1019 m-3, and nH/nH2 ≈ 0.5 at standard operational parameters). The analysis of the Fulcher transition revealed a non-thermal "hockey-stick" rotational population of the hydrogen molecules. At varying RF power, the measurements at the on-axis line of sight (LOS) showed a peak in the rotational temperatures between 25 and 40 kW of RF power, whereas a steady decrease with power was observed at a tilted LOS, indicating the presence of strong plasma parameter gradients.
Determination of a suitable parameter field for the active fluid jet polishing process
NASA Astrophysics Data System (ADS)
Maurer, Roland; Biskup, Heiko; Trum, Christian; Rascher, Rolf; Wünsche, Christine
2013-09-01
In 2012 a well-known company in the field of high precision optics assigned the University of Applied Sciences Deggendorf to determine a suitable parameter field for the active fluid jet polishing (AFJP) process in order to reach a surface accuracy of at least lambda / 5. The active fluid jet polishing is a relatively new and an affordable sub-aperture polishing process. For a fast and precise identification of the parameter field a considered design of experiment is necessary. The available control variables were the rotational speed of the nozzle, the distance between the test object and the jet, the feed rate, the material of the pin inside the nozzle and the material of the test object itself. In order to reach a significant data density on the one hand and to minimize the number of test runs on the other hand a meander shaped tool path was chosen. At each blank nine paths had been driven whereby at each path another parameter combination was picked. Thus with only one test object nine parameter settings may be evaluated. For the automatized analysis of the tracks a software tool was developed. The software evaluates ten sections which orthogonally intersect the nine tracks on the test-lens. The significant measurement parameters per section are the width and the height of each path as well as the surface roughness within the polished tracks. With the aid of these parameters and further statistical evaluations a suitable parameter field for the goal to find a constant and predictable removal spot was determined. Furthermore up to now over 60 test runs have been successfully finished with nine parameter combinations in each case. As a consequence a test evaluation by hand would be very time-consuming and the software facilitates it dramatically.
Polynomial force approximations and multifrequency atomic force microscopy.
Platz, Daniel; Forchheimer, Daniel; Tholén, Erik A; Haviland, David B
2013-01-01
We present polynomial force reconstruction from experimental intermodulation atomic force microscopy (ImAFM) data. We study the tip-surface force during a slow surface approach and compare the results with amplitude-dependence force spectroscopy (ADFS). Based on polynomial force reconstruction we generate high-resolution surface-property maps of polymer blend samples. The polynomial method is described as a special example of a more general approximative force reconstruction, where the aim is to determine model parameters that best approximate the measured force spectrum. This approximative approach is not limited to spectral data, and we demonstrate how it can be adapted to a force quadrature picture.
NASA Astrophysics Data System (ADS)
Morin, José A.; Ibarra, Borja; Cao, Francisco J.
2016-05-01
Single-molecule manipulation experiments of molecular motors provide essential information about the rate and conformational changes of the steps of the reaction located along the manipulation coordinate. This information is not always sufficient to define a particular kinetic cycle. Recent single-molecule experiments with optical tweezers showed that the DNA unwinding activity of a Phi29 DNA polymerase mutant presents a complex pause behavior, which includes short and long pauses. Here we show that different kinetic models, considering different connections between the active and the pause states, can explain the experimental pause behavior. Both the two independent pause model and the two connected pause model are able to describe the pause behavior of a mutated Phi29 DNA polymerase observed in an optical tweezers single-molecule experiment. For the two independent pause model all parameters are fixed by the observed data, while for the more general two connected pause model there is a range of values of the parameters compatible with the observed data (which can be expressed in terms of two of the rates and their force dependencies). This general model includes models with indirect entry and exit to the long-pause state, and also models with cycling in both directions. Additionally, assuming that detailed balance is verified, which forbids cycling, this reduces the ranges of the values of the parameters (which can then be expressed in terms of one rate and its force dependency). The resulting model interpolates between the independent pause model and the indirect entry and exit to the long-pause state model
NASA Astrophysics Data System (ADS)
Wang, Kesheng; Cheng, Jia; Yao, Shiji; Lu, Yijia; Ji, Linhong; Xu, Dengfeng
2016-12-01
Electrostatic force measurement at the micro/nano scale is of great significance in science and engineering. In this paper, a reasonable way of applying voltage is put forward by taking an electrostatic chuck in a real integrated circuit manufacturing process as a sample, applying voltage in the probe and the sample electrode, respectively, and comparing the measurement effect of the probe oscillation phase difference by amplitude modulation atomic force microscopy. Based on the phase difference obtained from the experiment, the quantitative dependence of the absolute magnitude of the electrostatic force on the tip-sample distance and applied voltage is established by means of theoretical analysis and numerical simulation. The results show that the varying characteristics of the electrostatic force with the distance and voltage at the micro/nano scale are similar to those at the macroscopic scale. Electrostatic force gradually decays with increasing distance. Electrostatic force is basically proportional to the square of applied voltage. Meanwhile, the applicable conditions of the above laws are discussed. In addition, a comparison of the results in this paper with the results of the energy dissipation method shows the two are consistent in general. The error decreases with increasing distance, and the effect of voltage on the error is small.
Determination of hydraulic fracture parameters using a non-stationary fluid injection
NASA Astrophysics Data System (ADS)
Valov, A. V.; Golovin, S. V.
2016-06-01
In this paper, one provides a theoretical justification of the possibility of hydraulic fracture parameters determination by using a non-stationary fluid injection. It is assumed that the fluid is pumped into the fractured well with the time-periodic flow rate. It is shown that there is a phase shift between waves of fluid pressure and velocity. For the modelling purposes, the length and width of the fracture are assumed to be fixed. In the case of infinite fracture, one constructs an exact solution that ensures analytical determination of the phase shift in terms of the physical parameters of the problem. In the numerical calculation, the phase shift between pressure and velocity waves is found for a finite fracture. It is shown that the value of the phase shift depends on the physical parameters and on the fracture geometry. This makes it possible to determine parameters of hydraulic fracture, in particular its length, by the experimental measurement of the time shift and comparison with the numerical solution.
Spectrophotometric determination of turbid optical parameters without using an integrating sphere.
Liang, Xiaohui; Li, Meihua; Lu, Jun Q; Huang, Chuanwei; Feng, Yuanming; Sa, Yu; Ding, Junhua; Hu, Xin-Hua
2016-03-10
Spectrophotometric quantification of turbidity by multiple optical parameters has wide-ranging applications in material analysis and life sciences. A robust system design needs to combine hardware for precise measurement of light signals with software to accurately model measurement configuration and rapidly solve a sequence of challenging inverse problems. We have developed and validated a design approach and performed system validation based on radiative transfer theory for determination of absorption coefficient, scattering coefficient, and anisotropy factor without using an integrating sphere. Accurate and rapid determination of parameters and spectra is achieved for microsphere suspension samples by combining photodiode-based measurement of four signals with the Monte Carlo simulation and perturbation-based inverse calculations. The three parameters of microsphere suspension samples have been determined from the measured signals as functions of wavelength from 400 to 800 nm and agree with calculated results based on the Mie theory. It has been shown that the inverse problems in the cases of microsphere suspension samples are well posed with convex cost functions to yield unique solutions, and it takes about 1 min to obtain the three parameters per wavelength.
Use of a probing pulsed magnetic field for determining plasma parameters
NASA Astrophysics Data System (ADS)
Rousskikh, A. G.; Oreshkin, V. I.; Zhigalin, A. S.; Yushkov, G. Yu.
2016-11-01
A novel, simple, and readily usable method is proposed for measuring the electrical conductivity and temperature of a plasma. The method is based on the interaction of the test plasma with a pulsed magnetic field. The electric signals induced by the magnetic field in the circuits of two probes (miniature solenoids), one immersed in the test plasma and the other placed outside the plasma, provide data for estimating the plasma parameters. The method was verified experimentally by determining the parameters of the plasma flows generated in the cathode spots high-current pulsed vacuum arcs that were used to form cylindrical shells of bismuth Z-pinch plasma.
Determination of Geometric and Kinematical Parameters of Coronal Mass Ejections Using STEREO Data
NASA Astrophysics Data System (ADS)
Fainshtein, V. G.; Tsivileva, D. M.; Kashapova, L. K.
2010-03-01
We present a new, relatively simple and fast method to determine true geometric and kinematical CME parameters from simultaneous STEREO A, B observations of CMEs. These parameters are the three-dimensional direction of CME propagation, velocity and acceleration of CME front, CME angular sizes and front position depending on time. The method is based on the assumption that CME shape may be described by a modification of so-called ice-cream cone models. The method has been tested for several CMEs.
Determination of crack morphology parameters from service failures for leak-rate analyses
Wilkowski, G.; Ghadiali, N.; Paul, D.
1997-04-01
In leak-rate analyses described in the literature, the crack morphology parameters are typically not well agreed upon by different investigators. This paper presents results on a review of crack morphology parameters determined from examination of service induced cracks. Service induced cracks were found to have a much more tortuous flow path than laboratory induced cracks due to crack branching associated with the service induced cracks. Several new parameters such as local and global surface roughnesses, as well as local and global number of turns were identified. The effect of each of these parameters are dependent on the crack-opening displacement. Additionally, the crack path is typically assumed to be straight through the pipe thickness, but the service data show that the flow path can be longer due to the crack following a fusion line, and/or the number of turns, where the number of turns in the past were included as a pressure drop term due to the turns, but not the longer flow path length. These parameters were statistically evaluated for fatigue cracks in air, corrosion-fatigue, IGSCC, and thermal fatigue cracks. A refined version of the SQUIRT leak-rate code was developed to account for these variables. Sample calculations are provided in this paper that show how the crack size can vary for a given leak rate and the statistical variation of the crack morphology parameters.
Determination of Eros Physical Parameters for Near Earth Asteroid Rendezvous Orbit Phase Navigation
NASA Technical Reports Server (NTRS)
Miller, J. K.; Antreasian, P. J.; Georgini, J.; Owen, W. M.; Williams, B. G.; Yeomans, D. K.
1995-01-01
Navigation of the orbit phase of the Near Earth steroid Rendezvous (NEAR) mission will re,quire determination of certain physical parameters describing the size, shape, gravity field, attitude and inertial properties of Eros. Prior to launch, little was known about Eros except for its orbit which could be determined with high precision from ground based telescope observations. Radar bounce and light curve data provided a rough estimate of Eros shape and a fairly good estimate of the pole, prime meridian and spin rate. However, the determination of the NEAR spacecraft orbit requires a high precision model of Eros's physical parameters and the ground based data provides only marginal a priori information. Eros is the principal source of perturbations of the spacecraft's trajectory and the principal source of data for determining the orbit. The initial orbit determination strategy is therefore concerned with developing a precise model of Eros. The original plan for Eros orbital operations was to execute a series of rendezvous burns beginning on December 20,1998 and insert into a close Eros orbit in January 1999. As a result of an unplanned termination of the rendezvous burn on December 20, 1998, the NEAR spacecraft continued on its high velocity approach trajectory and passed within 3900 km of Eros on December 23, 1998. The planned rendezvous burn was delayed until January 3, 1999 which resulted in the spacecraft being placed on a trajectory that slowly returns to Eros with a subsequent delay of close Eros orbital operations until February 2001. The flyby of Eros provided a brief glimpse and allowed for a crude estimate of the pole, prime meridian and mass of Eros. More importantly for navigation, orbit determination software was executed in the landmark tracking mode to determine the spacecraft orbit and a preliminary shape and landmark data base has been obtained. The flyby also provided an opportunity to test orbit determination operational procedures that will be
Review and test of methods for determination of the Schottky diode parameters
NASA Astrophysics Data System (ADS)
Olikh, O. Ya.
2015-07-01
This paper deals with the extraction of the Schottky diode parameters from a current-voltage characteristic. 10 analytical methods, 2 numerical methods, and 4 evolutionary algorithms of the series resistance, barrier height, and ideality factor determination are reviewed. The accuracy of the methods is quantified using a wide range of both ideal and noisy synthetic data. In addition, the influencing factors of the parameters extraction accuracy are estimated. The adaptive procedure, which improves the precision of analytical Gromov's method, is suggested. The use of Lambert W function has been shown to reduce the error of parameter extraction by numerical method. Finally, all methods are applied to experimental data. The most reliable and preferred methods are chosen.
NASA Astrophysics Data System (ADS)
Rueter, Keiti; Novikov, Ivan
2016-09-01
Parameters of a nuclear density distribution for an exotic nuclei with halo or skin structures can be determined from the experimentally measure interaction cross-section. In the presented work, to extract parameters for a halo and core, we compare experimental data on interaction cross section with reaction cross-sections calculated using expressions obtained in the Glauber Model and its optical approximation. These calculations are performed using Markov Chain Monte Carlo algorithm. In addition, we discuss the accuracy of the Monte Carlo approach to calculating the interaction and reaction cross-sections. The dependence of the accuracy of the density parameters of various exotic nuclei on the ``quality'' of the random numbers chains (here, ``quality'' is defined by lag-1 autocorrelation time of a sequence of random numbers) is obtained for the Gaussian density distribution for a core and the Gaussian density distribution for a halo. KY NSF EPSCoR Research Scholars Program.
Seol, Daehee; Park, Seongjae; Varenyk, Olexandr V.; ...
2016-07-28
Hysteresis loop analysis via piezoresponse force microscopy (PFM) is typically performed to probe the existence of ferroelectricity at the nanoscale. But, such an approach is rather complex in accurately determining the pure contribution of ferroelectricity to the PFM. We suggest a facile method to discriminate the ferroelectric effect from the electromechanical (EM) response through the use of frequency dependent ac amplitude sweep with combination of hysteresis loops in PFM. This combined study through experimental and theoretical approaches verifies that this method can be used as a new tool to differentiate the ferroelectric effect from the other factors that contribute tomore » the EM response.« less
Seol, Daehee; Park, Seongjae; Varenyk, Olexandr V.; Lee, Shinbuhm; Lee, Ho Nyung; Morozovska, Anna N.; Kim, Yunseok
2016-07-28
Hysteresis loop analysis via piezoresponse force microscopy (PFM) is typically performed to probe the existence of ferroelectricity at the nanoscale. But, such an approach is rather complex in accurately determining the pure contribution of ferroelectricity to the PFM. We suggest a facile method to discriminate the ferroelectric effect from the electromechanical (EM) response through the use of frequency dependent ac amplitude sweep with combination of hysteresis loops in PFM. This combined study through experimental and theoretical approaches verifies that this method can be used as a new tool to differentiate the ferroelectric effect from the other factors that contribute to the EM response.
NASA Technical Reports Server (NTRS)
Arnaiz, H. H.
1975-01-01
As part of a NASA program to evaluate current methods of predicting the performance of large, supersonic airplanes, the drag of the XB-70 airplane was measured accurately in flight at Mach numbers from 0.75 to 2.5. This paper describes the techniques used to determine engine net thrust and the drag forces charged to the propulsion system that were required for the in-flight drag measurements. The accuracy of the measurements and the application of the measurement techniques to aircraft with different propulsion systems are discussed. Examples of results obtained for the XB-70 airplane are presented.
Seol, Daehee; Park, Seongjae; Varenyk, Olexandr V.; Lee, Shinbuhm; Lee, Ho Nyung; Morozovska, Anna N.; Kim, Yunseok
2016-01-01
Hysteresis loop analysis via piezoresponse force microscopy (PFM) is typically performed to probe the existence of ferroelectricity at the nanoscale. However, such an approach is rather complex in accurately determining the pure contribution of ferroelectricity to the PFM. Here, we suggest a facile method to discriminate the ferroelectric effect from the electromechanical (EM) response through the use of frequency dependent ac amplitude sweep with combination of hysteresis loops in PFM. Our combined study through experimental and theoretical approaches verifies that this method can be used as a new tool to differentiate the ferroelectric effect from the other factors that contribute to the EM response. PMID:27466086
Accuracy of atmospheric parameters of FGK dwarfs determined by spectrum fitting
NASA Astrophysics Data System (ADS)
Ryabchikova, T.; Piskunov, N.; Pakhomov, Yu.; Tsymbal, V.; Titarenko, A.; Sitnova, T.; Alexeeva, S.; Fossati, L.; Mashonkina, L.
2016-02-01
We performed extensive tests of the accuracy of atmospheric parameter determination for FGK stars based on the spectrum fitting procedure Spectroscopy Made Easy (SME). Our stellar sample consists of 13 objects, including the Sun, in the temperature range 5000-6600 K and metallicity range -1.4-+0.4. The analysed stars have the advantage of having parameters derived by interferometry. For each star, we use spectra obtained with different spectrographs and different signal-to-noise ratios (S/N). For the fitting, we adopted three different sets of constraints and test how the derived parameters depend upon the spectral regions (masks) used in SME. We developed and implemented in SME a new method for estimating uncertainties in the resulting parameters based on fitting residuals, partial derivatives, and data uncertainties. For stars in the 5700-6600 K range, the best agreement with the effective temperatures derived by interferometry is achieved when spectrum fitting includes the H α and H β lines, while for cooler stars the choice of the mask does not affect the results. The derived atmospheric parameters do not strongly depend on spectral resolution and S/N of the observations, while the uncertainties in temperature and surface gravity increase with increasing effective temperature, with minima at 50 K in Teff and 0.1 dex in log g, for spectra with S/N=150-200. A non-local thermodynamic equilibrium (NLTE) analysis of the Ti I/Ti II and Fe I/Fe II ionization equilibria and abundances determined from the atomic C I (NLTE) and molecular CH species supports the parameters we derived with SME by fitting the observed spectra including the hydrogen lines.
Equation-free analysis of agent-based models and systematic parameter determination
NASA Astrophysics Data System (ADS)
Thomas, Spencer A.; Lloyd, David J. B.; Skeldon, Anne C.
2016-12-01
Agent based models (ABM)s are increasingly used in social science, economics, mathematics, biology and computer science to describe time dependent systems in circumstances where a description in terms of equations is difficult. Yet few tools are currently available for the systematic analysis of ABM behaviour. Numerical continuation and bifurcation analysis is a well-established tool for the study of deterministic systems. Recently, equation-free (EF) methods have been developed to extend numerical continuation techniques to systems where the dynamics are described at a microscopic scale and continuation of a macroscopic property of the system is considered. To date, the practical use of EF methods has been limited by; (1) the over-head of application-specific implementation; (2) the laborious configuration of problem-specific parameters; and (3) large ensemble sizes (potentially) leading to computationally restrictive run-times. In this paper we address these issues with our tool for the EF continuation of stochastic systems, which includes algorithms to systematically configuration problem specific parameters and enhance robustness to noise. Our tool is generic and can be applied to any 'black-box' simulator and determines the essential EF parameters prior to EF analysis. Robustness is significantly improved using our convergence-constraint with a corrector-repeat (C3R) method. This algorithm automatically detects outliers based on the dynamics of the underlying system enabling both an order of magnitude reduction in ensemble size and continuation of systems at much higher levels of noise than classical approaches. We demonstrate our method with application to several ABM models, revealing parameter dependence, bifurcation and stability analysis of these complex systems giving a deep understanding of the dynamical behaviour of the models in a way that is not otherwise easily obtainable. In each case we demonstrate our systematic parameter determination stage for
Determination of Optimum Cutting Parameters for Surface Roughness in Turning AL-B4C Composites
NASA Astrophysics Data System (ADS)
Channabasavaraja, H. K.; Nagaraj, P. M.; Srinivasan, D.
2016-09-01
Many materials such as alloys, composites find their applications on the basis of machinability, cost and availability. In the present work, machinability of Aluminium 1100 and Boron carbide (AL+ B4C) composite material is examined by using lathe tool dynometers (BANKA Lathe) by varying the cutting parameters like spindle speed, Depth of cut and Feed rate in 3 levels. Also, surface roughness is measured against the weight % of reinforcement in the composite (0, 4 and 8 %). From the study it is observed that the hardness of a composite material increases with increase in weight % of reinforcement material (B4C) by 26.27 and 66.7 % respectively. The addition of reinforcement materials influences the machinability. The cutting force in both X and Z direction were also found increment with the reinforcement percentage.
Online determination of biophysical parameters of mucous membranes of a human body
Lisenko, S A; Kugeiko, M M
2013-07-31
We have developed a method for online determination of biophysical parameters of mucous membranes (MMs) of a human body (transport scattering coefficient, scattering anisotropy factor, haemoglobin concentration, degrees of blood oxygenation, average diameter of capillaries with blood) from measurements of spectral and spatial characteristics of diffuse reflection. The method is based on regression relationships between linearly independent components of the measured light signals and the unknown parameters of MMs, obtained by simulation of the radiation transfer in the MM under conditions of its general variability. We have proposed and justified the calibration-free fibre-optic method for determining the concentration of haemoglobin in MMs by measuring the light signals diffusely reflected by the tissue in four spectral regions at two different distances from the illumination spot. We have selected the optimal wavelengths of optical probing for the implementation of the method. (laser applications in biology and medicine)
Note: A calibration method to determine the lumped-circuit parameters of a magnetic probe.
Li, Fuming; Chen, Zhipeng; Zhu, Lizhi; Liu, Hai; Wang, Zhijiang; Zhuang, Ge
2016-06-01
This paper describes a novel method to determine the lumped-circuit parameters of a magnetic inductive probe for calibration by using Helmholtz coils with high frequency power supply (frequency range: 10 kHz-400 kHz). The whole calibration circuit system can be separated into two parts: "generator" circuit and "receiver" circuit. By implementing the Fourier transform, two analytical lumped-circuit models, with respect to these separated circuits, are constructed to obtain the transfer function between each other. Herein, the precise lumped-circuit parameters (including the resistance, inductance, and capacitance) of the magnetic probe can be determined by fitting the experimental data to the transfer function. Regarding the fitting results, the finite impedance of magnetic probe can be used to analyze the transmission of a high-frequency signal between magnetic probes, cables, and acquisition system.
Note: A calibration method to determine the lumped-circuit parameters of a magnetic probe
NASA Astrophysics Data System (ADS)
Li, Fuming; Chen, Zhipeng; Zhu, Lizhi; Liu, Hai; Wang, Zhijiang; Zhuang, Ge
2016-06-01
This paper describes a novel method to determine the lumped-circuit parameters of a magnetic inductive probe for calibration by using Helmholtz coils with high frequency power supply (frequency range: 10 kHz-400 kHz). The whole calibration circuit system can be separated into two parts: "generator" circuit and "receiver" circuit. By implementing the Fourier transform, two analytical lumped-circuit models, with respect to these separated circuits, are constructed to obtain the transfer function between each other. Herein, the precise lumped-circuit parameters (including the resistance, inductance, and capacitance) of the magnetic probe can be determined by fitting the experimental data to the transfer function. Regarding the fitting results, the finite impedance of magnetic probe can be used to analyze the transmission of a high-frequency signal between magnetic probes, cables, and acquisition system.
Barz, Tilman; Löffler, Verena; Arellano-Garcia, Harvey; Wozny, Günter
2010-06-25
In this work, parameters of the steric mass-formalism SMA are optimally ascertained for a reliable determination of the adsorption isotherms of beta-lactoglobulin A and B under non-isocratic conditions. For this purpose, static batch experiments are used in contrast to the protocols based on different experimental steps, which use a chromatographic column. It is shown that parameters can already be determined for a small number of experiments by using a systematic procedure based on optimal model-based experimental design and an efficient NLP-solver. The in different works observed anti-Langmuir shape of the isotherm for small concentrations of beta-lactoglobulin A was corroborated. Moreover, we also found indications for a porosity variation with changing protein concentrations.
Method for Determining the D{sup 0}-D{sup 0} Mixing Parameters
Sinha, Nita; Sinha, Rahul; Browder, T. E.; Pakvasa, Sandip; Deshpande, N. G.
2007-12-31
We propose a new method to determine the mass and width differences of the two D meson mass eigenstates as well as the CP violating parameters associated with D{sup 0}-D{sup 0} mixing. We show that an accurate measurement of all the mixing parameters is possible for an arbitrary CP violating phase, by combining observables from a time dependent study of D decays to a doubly Cabibbo suppressed mode with information from a CP eigenstate. As an example we consider D{sup 0}{yields}K*{sup 0}{pi}{sup 0} decays where the K*{sup 0} is reconstructed in both K{sup +}{pi}{sup -} and K{sub S}{pi}{sup 0}. We also show that decays to the CP eigenstate D{yields}K{sup +}K{sup -} together with D{yields}K{sup +}{pi}{sup -} decays can be used to extract all the mixing parameters. There is a fourfold ambiguity in the solutions for x and y in both the cases. A combined analysis using D{sup 0}{yields}K*{sup 0}{pi}{sup 0} and D{yields}K{sup +}K{sup -} can also be used to reduce the ambiguity in the determination of parameters.
Determination of Hapke's Equation Parameters Using Multi-angular Bidirectional Reflectance Spectra.
NASA Astrophysics Data System (ADS)
Cord, A.; Pinet, P.; Daydou, Y.; Chevrel, S.
Hapke's equation of radiative transfer provides a basic rigorous description of pho- tometric behavior of a powdered mineral mixture in terms of physically meaningful parameters characterizing multiple scattering, phase function, opposition effect, and roughness. However values of parameters involved in Hapke's equation are only par- tially known for typical planetary materials, and their complex determination hampers the quantification of materials abundance present in a multispectral scenes, when ap- plying a non linear spectral mixture. The objective of this investigation is to present a reliable method, based on a genetic algorithm, allowing to solve simultaneously all the parameters involved in Hapke's equation. This can be achieved with multi-angular hyperspectral images and do not require any a priori knowledge of the target under study. Using a spectral imaging facility, operational at the Observatoire Midi-Pyrenees, France and dedicated to the measurement along the 0.40 - 1.05 mm domain of the multi-angular and multispectral properties of macroscopic surfaces (200 x 200 mm) with a submillimeter spatial resolution, this new method is applied on three powdered soils with four grain sizes sorting. The first results are compared with the literature and their analysis determines the success and limitations of such an approach. A by-product of this application is the derivation of Hapke parameters that may be used in future reflectance data interpretations and acquisition (e.g. AMIE / SMART-1, Lunar A, Selene optical instruments).
Hopkins, David L; Holman, Benjamin W B; van de Ven, Remy J
2015-02-01
Carcase pH and temperature decline rates influence lamb tenderness; therefore pH decline parameters are beneficial when modelling tenderness. These include pH at temperature 18 °C (pH@Temp18), temperature when pH is 6 (Temp@pH6), and pH at 24 h post-mortem (pH24). This study aimed to establish a relationship between shear force (SF) as a proxy for tenderness and carcase pH decline parameters estimated using both linear and spline estimation models for the m. longissimus lumborum (LL). The study also compared abattoirs regarding their achievement of ideal pH decline, indicative of optimal tenderness. Based on SF measurements of LL and m. semimembranosus collected as part of the Information Nucleus slaughter programme (CRC for Sheep Industry Innovation) this study found significant relationships between tenderness and pH24LL, consistent across the meat cuts and ageing periods examined. Achievement of ideal pH decline was shown not to have significantly differed across abattoirs, although rates of pH decline varied significantly across years within abattoirs.
Parameter-free determination of actual temperature at chemical freeze-out in nuclear interactions
NASA Astrophysics Data System (ADS)
Panagiotou, A. D.; Mavromanolakis, G.; Tzoulis, J.
1995-07-01
We propose a method to determine the actual temperature at chemical freeze-out in relativistic nucleus-nucleus collisions, using the experimental μq/T and μs/T values, obtained from strange particle ratios. We employ the Hadron Gas formalism, assuming only local thermal equilibration, to relate the quarkchemical potential and temperature. This relation constrains the allowed values of μq/T, μs/T and T, enabling the determination of the actual temperature. Comparison of the inverse slope parameter of the mT-distributions with the actual temperature determines the transverse flow velocity of the fireball matter. Knowledge of these quantities is essential in determining the EoS of nuclear matter and in evaluating interactions with regard to a possible phase transition to QGP.
Collins, J.L.
2005-10-28
The objective of this report is to describe a simple but very useful experimental methodology that was used to determine optimum process parameters for preparing several hydrous metal-oxide gel spheres by the internal gelation process. The method is inexpensive and very effective in collection of key gel-forming data that are needed to prepare the hydrous metal-oxide microspheres of the best quality for a number of elements.
NASA Astrophysics Data System (ADS)
Astafurov, S. V.; Shilko, E. V.; Dimaki, A. V.; Psakhie, S. G.
2016-11-01
The paper is devoted to theoretical investigation of peculiarities of inelastic deformation of porous brittle materials in constrained conditions. The study was based on computer-aided simulation by movable cellular automaton method. Analysis of the simulation results allowed to estimate values of some rheological parameters of porous brittle materials and to determine the limits of applicability of Mises-Schleicher equation for description of the inelastic deformation of such materials under axial compression in constrained conditions.
Determination of the quadratic slope parameter in eta-->3pi(0) decay.
Tippens, W B; Prakhov, S; Allgower, C E; Bekrenev, V; Berger, E; Briscoe, W J; Clajus, M; Comfort, J R; Craig, K; Efendiev, A; Grosnick, D; Holstein, B R; Huber, G M; Isenhower, D; Knecht, N; Koetke, D; Koulbardis, A; Kozlenko, N; Kruglov, S; Lolos, G J; Lopatin, I; Manley, D M; Marusić, A; Manweiler, R; McDonald, S; Nefkens, B M; Olmsted, J; Papandreou, Z; Phaisangittisakul, N; Price, J W; Pulver, M; Ramirez, A F; Sadler, M E; Shafi, A; Spinka, H; Stanislaus, S; Starostin, A; Staudenmaier, H M
2001-11-05
We have determined the quadratic slope parameter alpha for eta-->3pi(0) to be alpha = -0.031(4) from a 99% pure sample of 10(6)eta-->3pi(0) decays produced in the reaction pi(-)p-->n(eta) close to the eta threshold using the Crystal Ball detector at the AGS. The result is four times more precise than the present world data and disagrees with current chiral perturbation theory calculations by about four standard deviations.
Determination of the kinetic parameters of BeO using isothermal decay method.
Azorin Nieto, Juan; Vega, Claudia Azorin; Montalvo, Teodoro Rivera; Cabrera, Eugenio Torijano
2016-02-01
Most of the existing methods for obtaining the frequency factors make use of the trap depth (activation energy) making some assumptions about the order of the kinetics. This causes inconsistencies in the reported values of trapping parameters due that the values of the activation energy obtained by different methods differ appreciably among them. Then, it is necessary to use a method independent of the trap depth making use of the isothermal luminescence decay (ILD) method. The trapping parameters associated with the prominent glow peak of BeO (280°C) are reported using ILD method. As a check, the trap parameters are also calculated by glow curve shape (Chen's) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods. ILD method was used for determining the trapping parameters of BeO. Results obtained applying this method are in good agreement with those obtained using other methods, except in the value of the frequency factor.
NASA Astrophysics Data System (ADS)
Bustos, Cesar; Sandeen, Ben; Chennakesavalu, Shriram; Littenberg, Tyson; Farr, Ben; Kalogera, Vassiliki
2016-01-01
Gravitational Waves (GWs) were predicted by Einstein's Theory of General Relativity as ripples in space-time that propagate outward from a source. Strong GW sources consist of compact binary systems such as Binary Neutron Stars (BNS) or Binary Black Holes (BBHs) that experience orbital shrinkage (inspiral) and eventual merger. Indirect evidence for the existence of GWs has been obtained through radio pulsar studies in BNS systems. A study of BBHs and other compact objects has limitations in the electromagnetic spectrum, therefore direct detections of GWs will open a new window into their nature. The effort targeting direct GWs detection is anchored on the development of a detector known as Advanced LIGO (Laser Interferometer Gravitational Wave Observation). Although detecting GW sources represents an anticipated breakthrough in physics, making GW astrophysics a reality critically relies on our ability to determine and measure the physical parameters associated with GW sources. We use Markov Chain Monte Carlo (MCMC) simulations on high-performance computing clusters for parameter estimation on high dimensional spaces (GW sources - 15 parameters). The quality of GW parameter estimation greatly depends on having the best possible knowledge of the expected waveform. Unfortunately, BBH GW production is very complex and our best waveforms are not valid across the full parameter space. With large-scale simulations we examine quantitatively the limitations of these waveforms in terms of extracting the astrophysical properties of BBH GW sources. We find that current waveforms are inadequate for BBH of unequal masses and demonstrate that improved waveforms are critically needed.
Considering uncertainties in the determination of earthquake source parameters from seismic spectra
NASA Astrophysics Data System (ADS)
Garcia-Aristizabal, Alexander; Caciagli, Marco; Selva, Jacopo
2016-11-01
In this paper, we present a method for handling uncertainties in the determination of the source parameters of earthquakes from spectral data. We propose a robust framework for estimating earthquake source parameters and relative uncertainties, which are propagated down to the estimation of basic seismic parameters of interest such as the seismic moment, the moment magnitude, the source size and the static stress drop. In practice, we put together a Bayesian approach for model parameter estimation and a weighted statistical mixing of multiple solutions obtained from a network of instruments, providing a useful framework for extracting meaningful data from intrinsically uncertain data sets. The Bayesian approach used to estimate the source spectra parameters is a simple but powerful mechanism for non-linear model fitting, providing also the opportunity to naturally propagate uncertainties and to assess the quality and uniqueness of the solution. Another important added value of such an approach is the possibility of integrating information from the expertise of seismologists. Such data can be encoded in a prior state of information that is then updated with the information provided by seismological data. The performance of the proposed approach is demonstrated analysing data from the 1909 April 23 earthquake occurred near Benavente (Portugal).
Qiu, Zhihai; Yao, Guangping; Chen, Defu; Wang, Ying; Gu, Ying; Li, Buhong
2016-01-01
Characterizing port wine stains (PWS) with its optical parameters [i.e. absorption coefficient (μ a) and reduced scattering coefficient (μ s')] and microvascular parameters [i.e. blood volume fraction (BVF), mean vessel diameter (MVD), and oxygen saturation (StO2)] is extremely important for elucidating the mechanisms for its light-based treatments, such as pulsed dye laser and photodynamic therapy. In this study, a customized diffuse reflectance spectroscopy (DRS) probe with an appropriate source-detector distance was used to measure the diffuse reflectance spectra of PWS lesions in clinical practice. The results demonstrate that optical parameters of different types of PWS lesions can be accurately extracted by fitting the DRS with diffusion equation. Since the sampling depth of the probe coincides with the depth distribution of abnormal vasculature in PWS, the obtained microvascular parameters of PWS lesions that changed from pink to purple are in agreement with the corresponding physiological conditions. This study suggests that DRS can be utilized to quantitatively determine the optical and microvascular parameters of PWS lesions, which have the potential for planning the protocol and predicting the efficiency for light-based PWS treatments.
Avcu, N; Alyürük, H; Demir, G K; Pekergin, F; Cavas, L; Güzeliş, C
2015-06-01
This paper employs the root locus method to conduct a detailed investigation of the parameter regions that ensure bistability in a well-studied gene regulatory network namely, lac operon of Escherichia coli (E. coli). In contrast to previous works, the parametric bistability conditions observed in this study constitute a complete set of necessary and sufficient conditions. These conditions were derived by applying the root locus method to the polynomial equilibrium equation of the lac operon model to determine the parameter values yielding the multiple real roots necessary for bistability. The lac operon model used was defined as an ordinary differential equation system in a state equation form with a rational right hand side, and it was compatible with the Hill and Michaelis-Menten approaches of enzyme kinetics used to describe biochemical reactions that govern lactose metabolism. The developed root locus method can be used to study the steady-state behavior of any type of convergent biological system model based on mass action kinetics. This method provides a solution to the problem of analyzing gene regulatory networks under parameter uncertainties because the root locus method considers the model parameters as variable, rather than fixed. The obtained bistability ranges for the lac operon model parameters have the potential to elucidate the appearance of bistability for E. coli cells in in vivo experiments, and they could also be used to design robust hysteretic switches in synthetic biology.
Determination of MSSM Parameters from LHC and ILCObservables in a Global Fit
Bechtle, Philip; Desch, Klaus; Porod, Werner; Wienemann, Peter; /Freiburg U.
2005-12-02
We present the results of a realistic global fit of the Lagrangian parameters of the Minimal Supersymmetric Standard Model assuming universality for the first and second generation and real parameters. No assumptions on the SUSY breaking mechanism are made. The fit is performed using the precision of future mass measurements of superpartners at the LHC and mass and polarized topological cross-section measurements at the ILC. Higher order radiative corrections are accounted for wherever possible to date. Results are obtained for a modified SPS1a MSSM benchmark scenario but they were checked not to depend critically on this assumption. Exploiting a simulated annealing algorithm, a stable result is obtained without any a priori assumptions on the values of the fit parameters. Most of the Lagrangian parameters can be extracted at the percent level or better if theoretical uncertainties are neglected. Neither LHC nor ILC measurements alone will be sufficient to obtain a stable result. The effects of theoretical uncertainties arising from unknown higher-order corrections and parametric uncertainties are examined qualitatively. They appear to be relevant and the result motivates further precision calculations. The obtained parameters at the electroweak scale are used for a fit of the parameters at high energy scales within the bottom-up approach. In this way regularities at these scales are explored and the underlying model can be determined with hardly any theoretical bias. Fits of high-scale parameters to combined LHC+ILC measurements within the mSUGRA framework reveal that even tiny distortions in the low-energy mass spectrum already lead to unacceptable {chi}{sup 2} values. This does not hold for ''LHC only'' inputs.
Determination of the Michel parameters and the τ neutrino helicity in τ decay
NASA Astrophysics Data System (ADS)
Alexander, J. P.; Bebek, C.; Berger, B. E.; Berkelman, K.; Bloom, K.; Cassel, D. G.; Cho, H. A.; Coffman, D. M.; Crowcroft, D. S.; Dickson, M.; Drell, P. S.; Ecklund, K. M.; Ehrlich, R.; Elia, R.; Foland, A. D.; Gaidarev, P.; Galik, R. S.; Gittelman, B.; Gray, S. W.; Hartill, D. L.; Heltsley, B. K.; Hopman, P. I.; Kandaswamy, J.; Kim, P. C.; Kreinick, D. L.; Lee, T.; Liu, Y.; Ludwig, G. S.; Masui, J.; Mevissen, J.; Mistry, N. B.; Ng, C. R.; Nordberg, E.; Ogg, M.; Patterson, J. R.; Peterson, D.; Riley, D.; Soffer, A.; Valant-Spaight, B.; Ward, C.; Athanas, M.; Avery, P.; Jones, C. D.; Lohner, M.; Prescott, C.; Yelton, J.; Zheng, J.; Brandenburg, G.; Briere, R. A.; Gao, Y. S.; Kim, D. Y.-J.; Wilson, R.; Yamamoto, H.; Browder, T. E.; Li, F.; Li, Y.; Rodriguez, J. L.; Bergfeld, T.; Eisenstein, B. I.; Ernst, J.; Gladding, G. E.; Gollin, G. D.; Hans, R. M.; Johnson, E.; Karliner, I.; Marsh, M. A.; Palmer, M.; Selen, M.; Thaler, J. J.; Edwards, K. W.; Bellerive, A.; Janicek, R.; Macfarlane, D. B.; McLean, K. W.; Patel, P. M.; Sadoff, A. J.; Ammar, R.; Baringer, P.; Bean, A.; Besson, D.; Coppage, D.; Darling, C.; Davis, R.; Hancock, N.; Kotov, S.; Kravchenko, I.; Kwak, N.; Anderson, S.; Kubota, Y.; Lattery, M.; Lee, S. J.; O'neill, J. J.; Patton, S.; Poling, R.; Riehle, T.; Savinov, V.; Smith, A.; Alam, M. S.; Athar, S. B.; Ling, Z.; Mahmood, A. H.; Severini, H.; Timm, S.; Wappler, F.; Anastassov, A.; Blinov, S.; Duboscq, J. E.; Fisher, K. D.; Fujino, D.; Gan, K. K.; Hart, T.; Honscheid, K.; Kagan, H.; Kass, R.; Lee, J.; Spencer, M. B.; Sung, M.; Undrus, A.; Wanke, R.; Wolf, A.; Zoeller, M. M.; Nemati, B.; Richichi, S. J.; Ross, W. R.; Skubic, P.; Wood, M.; Bishai, M.; Fast, J.; Gerndt, E.; Hinson, J. W.; Menon, N.; Miller, D. H.; Shibata, E. I.; Shipsey, I. P.; Yurko, M.; Gibbons, L.; Glenn, S.; Johnson, S. D.; Kwon, Y.; Roberts, S.; Thorndike, E. H.; Jessop, C. P.; Lingel, K.; Marsiske, H.; Perl, M. L.; Ugolini, D.; Wang, R.; Zhou, X.; Coan, T. E.; Fadeyev, V.; Korolkov, I.; Maravin, Y.; Narsky, I.; Shelkov, V.; Staeck, J.; Stroynowski, R.; Volobouev, I.; Ye, J.; Artuso, M.; Efimov, A.; Frasconi, F.; Gao, M.; Goldberg, M.; He, D.; Kopp, S.; Moneti, G. C.; Mountain, R.; Schuh, S.; Skwarnicki, T.; Stone, S.; Viehhauser, G.; Xing, X.; Bartelt, J.; Csorna, S. E.; Jain, V.; Marka, S.; Godang, R.; Kinoshita, K.; Lai, I. C.; Pomianowski, P.; Schrenk, S.; Bonvicini, G.; Cinabro, D.; Greene, R.; Perera, L. P.; Zhou, G. J.; Barish, B.; Chadha, M.; Chan, S.; Eigen, G.; Miller, J. S.; O'grady, C.; Schmidtler, M.; Urheim, J.; Weinstein, A. J.; Würthwein, F.; Asner, D. M.; Bliss, D. W.; Brower, W. S.; Masek, G.; Paar, H. P.; Prell, S.; Sharma, V.; Gronberg, J.; Hill, T. S.; Kutschke, R.; Lange, D. J.; Menary, S.; Morrison, R. J.; Nelson, H. N.; Nelson, T. K.; Qiao, C.; Richman, J. D.; Roberts, D.; Ryd, A.; Witherell, M. S.; Balest, R.; Behrens, B. H.; Cho, K.; Ford, W. T.; Park, H.; Rankin, P.; Roy, J.; Smith, J. G.
1997-11-01
Using the CLEO II detector at the Cornell Electron Storage Ring operated at s=10.6 GeV, we have determined the Michel parameters ρ, ξ, and δ in τ-/+-->l-/+νν¯ decay as well as the τ neutrino helicity parameter hντ in τ-/+-->π-/+π0ν decay. From a data sample of 3.02×106 produced τ pairs we analyzed events of the topologies e+e--->τ+τ--->(l+/-νν¯)(π-/+π0ν) and e+e--->τ+τ--->(π+/-π0ν¯)(π-/+π0ν). We obtain ρ=0.747ρ=0.747+/-0.010+/-0.006, ξ=1.007+/-0.040+/-0.015, ξδ=0.745+/-0.026+/-0.009, and hντ=-0.995+/-0.010+/-0.003, where we have used the previously determined sign of hντ [ARGUS Collaboration, H. Albrecht et al., Z. Phys. C 58, 61 (1993); Phys. Lett. B 349, 576 (1995)]. We also present the Michel parameters as determined from the electron and muon samples separately. All results are in agreement with the standard model V-A interaction.
SDSS-II: Determination of shape and color parameter coefficients for SALT-II fit model
Dojcsak, L.; Marriner, J.; /Fermilab
2010-08-01
In this study we look at the SALT-II model of Type IA supernova analysis, which determines the distance moduli based on the known absolute standard candle magnitude of the Type IA supernovae. We take a look at the determination of the shape and color parameter coefficients, {alpha} and {beta} respectively, in the SALT-II model with the intrinsic error that is determined from the data. Using the SNANA software package provided for the analysis of Type IA supernovae, we use a standard Monte Carlo simulation to generate data with known parameters to use as a tool for analyzing the trends in the model based on certain assumptions about the intrinsic error. In order to find the best standard candle model, we try to minimize the residuals on the Hubble diagram by calculating the correct shape and color parameter coefficients. We can estimate the magnitude of the intrinsic errors required to obtain results with {chi}{sup 2}/degree of freedom = 1. We can use the simulation to estimate the amount of color smearing as indicated by the data for our model. We find that the color smearing model works as a general estimate of the color smearing, and that we are able to use the RMS distribution in the variables as one method of estimating the correct intrinsic errors needed by the data to obtain the correct results for {alpha} and {beta}. We then apply the resultant intrinsic error matrix to the real data and show our results.
NASA Astrophysics Data System (ADS)
Leroy, Frédéric
2016-10-01
Owing to its peculiar electronic properties, molybdenum disulfide (MoS2) has been the subject of a growing number of studies in the recent years. In applications, this material and other transition metal dichalcogenides (TMDs) may have to interact with a liquid or polymer phase as well as solutions of biomolecules. It is therefore of primary importance to understand the wetting and adhesion properties of TMDs. Starting from existing models, we derive Lennard-Jones parameters for the interaction between water and the basal plane of MoS2 that are consistent with recent wetting experiments. Molecular dynamics simulations indicate that a stack of only two MoS2 monolayers is necessary to capture the wetting behavior of bulk MoS2. It is found that the Coulomb interaction between water and monolayer and bilayer MoS2 plays no role in the related interfacial thermodynamics. Calculations with the optimized parameters show that the depth of the well of the interaction potential between water and bulk MoS2 is of the order of 8.2 kJ/mol. Such a value is comparable with what was found for graphite and consistent with the fact that the wetting angles of water on graphite and MoS2 are almost equal. The derivation of the force-field parameters is performed using a methodology which, contrary to previous studies, makes a consistent use of droplet calculations. The results of our work should find application in further simulation studies on the wetting behavior of TMDs and other dispersive materials.
NASA Astrophysics Data System (ADS)
Seçgin, Abdullah
2013-01-01
Statistical energy analysis (SEA) parameters such as average modal spacing, coupling loss factor and input power are numerically determined for point connected, directly coupled symmetrically laminated composite plates using a modal-based approach. The approach is an enhancement of classical wave transmission formula. Unlike most of the existing numerical or experimental techniques, the approach uses uncoupled plate modal information and treats substructure by means of averaged modal impedances. The procedure introduced here is verified using analytical definitions of infinite orthotropic plates which physically resemble to laminated plates for (under) specific conditions, and is tested by performing experimental power injection method (PIM) for an actual, right-angled composite structure. In the development process, force and moment transmissions are individually considered in order to be consistent with analytical formulations. Modal information of composite plates is statistically evaluated by the discrete singular convolution method with random boundary conditions. Proposed methodology not only provides an efficient use of SEA method in high frequency vibration analysis of composite structures, but also enhances SEA accuracy in mid frequency region in which conventional SEA fails. Furthermore, the effect of orientation angles of laminations on SEA parameters are also discussed in mid and high frequency regions.
Inverse Force Determination on a Small Scale Launch Vehicle Model Using a Dynamic Balance
NASA Technical Reports Server (NTRS)
Ngo, Christina L.; Powell, Jessica M.; Ross, James C.
2017-01-01
A launch vehicle can experience large unsteady aerodynamic forces in the transonic regime that, while usually only lasting for tens of seconds during launch, could be devastating if structural components and electronic hardware are not designed to account for them. These aerodynamic loads are difficult to experimentally measure and even harder to computationally estimate. The current method for estimating buffet loads is through the use of a few hundred unsteady pressure transducers and wind tunnel test. Even with a large number of point measurements, the computed integrated load is not an accurate enough representation of the total load caused by buffeting. This paper discusses an attempt at using a dynamic balance to experimentally determine buffet loads on a generic scale hammer head launch vehicle model tested at NASA Ames Research Center's 11' x 11' transonic wind tunnel. To use a dynamic balance, the structural characteristics of the model needed to be identified so that the natural modal response could be and removed from the aerodynamic forces. A finite element model was created on a simplified version of the model to evaluate the natural modes of the balance flexures, assist in model design, and to compare to experimental data. Several modal tests were conducted on the model in two different configurations to check for non-linearity, and to estimate the dynamic characteristics of the model. The experimental results were used in an inverse force determination technique with a psuedo inverse frequency response function. Due to the non linearity, the model not being axisymmetric, and inconsistent data between the two shake tests from different mounting configuration, it was difficult to create a frequency response matrix that satisfied all input and output conditions for wind tunnel configuration to accurately predict unsteady aerodynamic loads.
Kulig, Waldemar; Pasenkiewicz-Gierula, Marta; Róg, Tomasz
2015-12-01
In this data article we provide topologies and force field parameters files for molecular dynamics simulations of lipids in the OPLS-aa force field using the GROMACS package. This is the first systematic parameterization of lipid molecules in this force field. Topologies are provided for four phosphatidylcholines: saturated DPPC, mono-cis unsaturated POPC and DOPC, and mono-trans unsaturated PEPC. Parameterization of the phosphatidylcholines was achieved in two steps: first, we supplemented the OPLS force field parameters for DPPC with new parameters for torsion angles and van der Waals parameters for the carbon and hydrogen atoms in the acyl chains, as well as new partial atomic charges and parameters for torsion angles in the phosphatidylcholine and glycerol moieties [1]. Next, we derived parameters for the cis and trans double bonds and the neighboring them single bonds [2]. Additionally, we provide GROMACS input files with parameters describing simulation conditions (md.mdp), which are strongly recommended to be used with these lipids models. The data are associated with the research article "Cis and trans unsaturated phosphatidylcholine bilayers: a molecular dynamics simulation study" [2] and provided as supporting materials.
Kulig, Waldemar; Pasenkiewicz-Gierula, Marta; Róg, Tomasz
2015-01-01
In this data article we provide topologies and force field parameters files for molecular dynamics simulations of lipids in the OPLS-aa force field using the GROMACS package. This is the first systematic parameterization of lipid molecules in this force field. Topologies are provided for four phosphatidylcholines: saturated DPPC, mono-cis unsaturated POPC and DOPC, and mono-trans unsaturated PEPC. Parameterization of the phosphatidylcholines was achieved in two steps: first, we supplemented the OPLS force field parameters for DPPC with new parameters for torsion angles and van der Waals parameters for the carbon and hydrogen atoms in the acyl chains, as well as new partial atomic charges and parameters for torsion angles in the phosphatidylcholine and glycerol moieties [1]. Next, we derived parameters for the cis and trans double bonds and the neighboring them single bonds [2]. Additionally, we provide GROMACS input files with parameters describing simulation conditions (md.mdp), which are strongly recommended to be used with these lipids models. The data are associated with the research article “Cis and trans unsaturated phosphatidylcholine bilayers: a molecular dynamics simulation study” [2] and provided as supporting materials. PMID:26568975
Diffractive index determination by Tikhonov regularization on forced string vibration data
NASA Astrophysics Data System (ADS)
Asekritova, Irina; Nilsson, Börje; Rydström, Sara
2009-03-01
Wave analysis is efficient for investigating the interior of objects. Examples are ultra sound examination of humans and radar using elastic and electromagnetic waves. A common procedure is inverse scattering where both transmitters and receivers are located outside the object or on its boundary. A variant is when both transmitters and receivers are located on the scattering object. The canonical model is a finite inhomogeneous string driven by a harmonic point force. The inverse problem for the determination of the diffractive index of the string is studied. This study is a first step to the problem for the determination of the mechanical strength of wooden logs. An inverse scattering theory is formulated incorporating two regularizing strategies. The results of simulations using this theory show that the suggested method works quite well and that the regularization methods based on the couple of spaces (L2, H1) could be very useful in such problems.
Motion Parameters Determination of the SC and Phobos in the Project Phobos-Grunt
NASA Technical Reports Server (NTRS)
Akim, E. L.; Stepanyants, V. A.; Tuchin, A. G.; Shishov, V. A.
2007-01-01
The SC "Phobos-Grunt" flight is planned to 2009 in Russia with the purpose to deliver to the Earth the soil samples of the Mars satellite Phobos. The mission will pass under the following scheme [1-4]: the SC flight from the Earth to the Mars, the SC transit on the Mars satellite orbit, the motion round the Mars on the observation orbit and on the quasi-synchronous one [5], landing on Phobos, taking of a ground and start in the direction to the Earth. The implementation of complicated dynamical operations in the Phobos vicinity is foreseen by the project. The SC will be in a disturbance sphere of gravitational fields from the Sun, the Mars and the Phobos. The SC orbit determination is carried out on a totality of trajectory measurements executed from ground tracking stations and measurements of autonomous systems onboard space vehicle relatively the Phobos. As ground measurements the radio engineering measurements of range and range rate are used. There are possible as onboard optical observations of the Phobos by a television system and ranges from the SC up to the Phobos surface by laser locator. As soon as the Phobos orbit accuracy is insufficient for a solution of a problem of landing its orbit determination will be carried out together with determination of the SC orbit. Therefore the algorithms for joint improving of initial conditions of the SC and the Phobos are necessary to determine parameters of the SC relative the Phobos motion within a single dynamical motion model. After putting on the martial satellite orbit, on the Phobos observation orbit, on the quasi-synchronous orbit in the Phobos vicinity the equipment guidance and the following process of the SC orbit determination relatively Phobos requires a priori knowledge of the Phobos orbit parameters with sufficiently high precision. These parameters should be obtained beforehand using both all modern observations and historical ones.
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2011-10-03
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Determination of HCME 3-D parameters using a full ice-cream cone model
NASA Astrophysics Data System (ADS)
Na, Hyeonock; Moon, Yong-Jae; Lee, Harim
2016-05-01
It is very essential to determine three dimensional parameters (e.g., radial speed, angular width, source location) of Coronal Mass Ejections (CMEs) for space weather forecast. Several cone models (e.g., an elliptical cone model, an ice-cream cone model, an asymmetric cone model) have been examined to estimate these parameters. In this study, we investigate which cone type is close to a halo CME morphology using 26 CMEs: halo CMEs by one spacecraft (SOHO or STEREO-A or B) and as limb CMEs by the other ones. From cone shape parameters of these CMEs such as their front curvature, we find that near full ice-cream cone type CMEs are much closer to observations than shallow ice-cream cone type CMEs. Thus we develop a new cone model in which a full ice-cream cone consists of many flat cones with different heights and angular widths. This model is carried out by the following steps: (1) construct a cone for given height and angular width, (2) project the cone onto the sky plane, (3) select points comprising the outer boundary, and (4) minimize the difference between the estimated projection speeds with the observed ones. By applying this model to 12 SOHO/LASCO halo CMEs, we find that 3-D parameters from our method are similar to those from other stereoscopic methods (a geometrical triangulation method and a Graduated Cylindrical Shell model) based on multi-spacecraft data. We are developing a general ice-cream cone model whose front shape is a free parameter determined by observations.
NASA Astrophysics Data System (ADS)
Akhter, Gulraiz; Hasan, M.
2016-01-01
In order to determine the groundwater resources and potentials of the Khanewal District of Pakistan, a geophysical method in combination with pumping test data were used. An analytical relationship between the aquifer parameters interpreted from surface geoelectrical method and pumping test was established in order to estimate aquifer parameters from surface measurements where no pumping tests exist. For the said purpose, 48 geoelectric investigations were carried out using Schlumberger vertical electrical sounding (VES). Seven of the soundings were conducted where pumping tests had been carried out at borehole sites. The vertical electrical sounding stations were interpreted, and resistivities and thickness parameters were calculated. The values of transmissivity and hydraulic conductivity were calculated using the Dar Zarrouk parameter. Transmissivity values obtained from pumping test data and the VES method range between 954 - 4263 m2/day and 200 - 5600 m2/day respectively. Hydraulic conductivity values determined from pumping test data and geoelectrical technique range between 15.9 - 60.9 m/day and 29.76 - 72.3 m/day respectively. The low values of transmissivity and hydraulic conductivity indicate clay or shale while high values are due to the presence of sand or gravel. A comparison of the transmissivity values obtained from pumping test data and surface geoelectrical method shows a positive correlation (R2 =0.90). Similarly, the regression between hydraulic conductivity determined from the pumping test data and the geoelectrical method is also positively correlated (R2 =0.96). The results provide a quick and useful estimation of aquifer properties and potentials.
Determining Parameters and Mechanisms of Colloid Retention and Release in Porous Media.
Bradford, Scott A; Torkzaban, Saeed
2015-11-10
A modeling framework is presented to determine fundamental parameters and controlling mechanisms of colloid (microbes, clays, and nanoparticles) retention and release on surfaces of porous media that exhibit wide distributions of nanoscale chemical heterogeneity, nano- to microscale roughness, and pore water velocity. Primary and/or secondary minimum interactions in the zone of electrostatic influence were determined over the heterogeneous solid surface. The Maxwellian kinetic energy model was subsequently employed to determine the probability of immobilization and diffusive release of colloids from each of these minima. In addition, a balance of applied hydrodynamic and resisting adhesive torques was conducted to determine locations of immobilization and hydrodynamic release in the presence of spatially variable water flow and microscopic roughness. Locations for retention had to satisfy both energy and torque balance conditions for immobilization, whereas release could occur either due to diffusion or hydrodynamics. Summation of energy and torque balance results over the elementary surface area of the porous medium provided estimates for colloid retention and release parameters that are critical to predicting environmental fate, including the sticking and release efficiencies and the maximum concentration of retained colloids on the solid phase. Nanoscale roughness and chemical heterogeneity produced localized primary minimum interactions that controlled long-term retention, even when mean chemical conditions were unfavorable. Microscopic roughness played a dominant role in colloid retention under low ionic strength and high hydrodynamic conditions, especially for larger colloids.
Study on determining the photometric parameters for a white LED using a light meter
NASA Astrophysics Data System (ADS)
Marcu, Alina E.; Dobre, Robert A.; Vlǎdescu, Marian
2016-12-01
The paper presents the experiments performed in order to determine the most suitable measuring mode which could be used to notably increase the accuracy of the photometric parameters determination for a white LED using a light meter with multiple measurement modes for various classic light sources like tungsten (incandescent), fluorescent, mercury and sodium based. Light meters are used for measuring the illuminance, which is a photometric parameter and its determination is based on the properties of human sight sense. Knowing how the sensitivity of the eye varies with the wavelength, the spectral response of the sensor and the spectral composition of the radiation emitted by a certain light source, a correction curve can be applied over the sensed values and obtain an accurate measurement. Nowadays many light meters can contain multiple calibration curves for typical light sources, but not for LEDs, especially for white ones. Since multiple measurements can be done using each correction curve, the authors conducted experiments to determine how to combine the aforementioned results to obtain a good estimate for the illuminance of white LEDs.
Modeling of Non-Gravitational Forces for Precise and Accurate Orbit Determination
NASA Astrophysics Data System (ADS)
Hackel, Stefan; Gisinger, Christoph; Steigenberger, Peter; Balss, Ulrich; Montenbruck, Oliver; Eineder, Michael
2014-05-01
Remote sensing satellites support a broad range of scientific and commercial applications. The two radar imaging satellites TerraSAR-X and TanDEM-X provide spaceborne Synthetic Aperture Radar (SAR) and interferometric SAR data with a very high accuracy. The precise reconstruction of the satellite's trajectory is based on the Global Positioning System (GPS) measurements from a geodetic-grade dual-frequency Integrated Geodetic and Occultation Receiver (IGOR) onboard the spacecraft. The increasing demand for precise radar products relies on validation methods, which require precise and accurate orbit products. An analysis of the orbit quality by means of internal and external validation methods on long and short timescales shows systematics, which reflect deficits in the employed force models. Following the proper analysis of this deficits, possible solution strategies are highlighted in the presentation. The employed Reduced Dynamic Orbit Determination (RDOD) approach utilizes models for gravitational and non-gravitational forces. A detailed satellite macro model is introduced to describe the geometry and the optical surface properties of the satellite. Two major non-gravitational forces are the direct and the indirect Solar Radiation Pressure (SRP). The satellite TerraSAR-X flies on a dusk-dawn orbit with an altitude of approximately 510 km above ground. Due to this constellation, the Sun almost constantly illuminates the satellite, which causes strong across-track accelerations on the plane rectangular to the solar rays. The indirect effect of the solar radiation is called Earth Radiation Pressure (ERP). This force depends on the sunlight, which is reflected by the illuminated Earth surface (visible spectra) and the emission of the Earth body in the infrared spectra. Both components of ERP require Earth models to describe the optical properties of the Earth surface. Therefore, the influence of different Earth models on the orbit quality is assessed. The scope of
Kaminski, George A.; Ponomarev, Sergei Y.; Liu, Aibing B.
2009-01-01
We are presenting POSSIM (POlarizable Simulations with Second order Interaction Model) – a software package and a set of parameters designed for molecular simulations. The key feature of POSSIM is that the electrostatic polarization is taken into account using a previously introduced fast formalism. This permits cutting computational cost of using the explicit polarization by about an order of magnitude. In this article, parameters for water, methane, ethane, propane, butane, methanol and NMA are introduced. These molecules are viewed as model systems for protein simulations. We have achieved our goal of ca. 0.5 kcal/mol accuracy for gas-phase dimerization energies and no more than 2% deviations in liquid state heats of vaporization and densities. Moreover, free energies of hydration of the polarizable methane, ethane and methanol have been calculated using the statistical perturbation theory. These calculations are a model for calculating protein pKa shifts and ligand binding affinities. The free energies of hydration were found to be 2.12 kcal/mol, 1.80 kcal/mol and −4.95 kcal/mol for methane, ethane and methanol, respectively. The experimentally determined literature values are 1.91 kcal/mol, 1.83 kcal/mol and −5.11 kcal/mol. The POSSIM average error in these absolute free energies of hydration is only about 0.13 kcal/mol. Using the statistical perturbation theory with polarizable force fields is not widespread, and we believe that this work opens road to further development of the POSSIM force field and its applications for obtaining accurate energies in protein-related computer modeling. PMID:20209038
Determination of parameters for successful spray coating of silicon microneedle arrays.
McGrath, Marie G; Vrdoljak, Anto; O'Mahony, Conor; Oliveira, Jorge C; Moore, Anne C; Crean, Abina M
2011-08-30
Coated microneedle patches have demonstrated potential for effective, minimally invasive, drug and vaccine delivery. To facilitate cost-effective, industrial-scale production of coated microneedle patches, a continuous coating method which utilises conventional pharmaceutical processes is an attractive prospect. Here, the potential of spray-coating silicon microneedle patches using a conventional film-coating process was evaluated and the key process parameters which impact on coating coalescence and weight were identified by employing a fractional factorial design to coat flat silicon patches. Processing parameters analysed included concentration of coating material, liquid input rate, duration of spraying, atomisation air pressure, gun-to-surface distance and air cap setting. Two film-coating materials were investigated; hydroxypropylmethylcellulose (HPMC) and carboxymethylcellulose (CMC). HPMC readily formed a film-coat on silicon when suitable spray coating parameter settings were determined. CMC films required the inclusion of a surfactant (1%, w/w Tween 80) to facilitate coalescence of the sprayed droplets on the silicon surface. Spray coating parameters identified by experimental design, successfully coated 280μm silicon microneedle arrays, producing an intact film-coat, which follows the contours of the microneedle array without occlusion of the microneedle shape. This study demonstrates a novel method of coating microneedle arrays with biocompatible polymers using a conventional film-coating process. It is the first study to indicate the thickness and roughness of coatings applied to microneedle arrays. The study also highlights the importance of identifying suitable processing parameters when film coating substrates of micron dimensions. The ability of a fractional factorial design to identify these critical parameters is also demonstrated. The polymer coatings applied in this study can potentially be drug loaded for intradermal drug and vaccine delivery.
Neuert, Mark A C; Dunning, Cynthia E
2013-09-01
Strain energy-based adaptive material models are used to predict bone resorption resulting from stress shielding induced by prosthetic joint implants. Generally, such models are governed by two key parameters: a homeostatic strain-energy state (K) and a threshold deviation from this state required to initiate bone reformation (s). A refinement procedure has been performed to estimate these parameters in the femur and glenoid; this study investigates the specific influences of these parameters on resulting density distributions in the distal ulna. A finite element model of a human ulna was created using micro-computed tomography (µCT) data, initialized to a homogeneous density distribution, and subjected to approximate in vivo loading. Values for K and s were tested, and the resulting steady-state density distribution compared with values derived from µCT images. The sensitivity of these parameters to initial conditions was examined by altering the initial homogeneous density value. The refined model parameters selected were then applied to six additional human ulnae to determine their performance across individuals. Model accuracy using the refined parameters was found to be comparable with that found in previous studies of the glenoid and femur, and gross bone structures, such as the cortical shell and medullary canal, were reproduced. The model was found to be insensitive to initial conditions; however, a fair degree of variation was observed between the six specimens. This work represents an important contribution to the study of changes in load transfer in the distal ulna following the implementation of commercial orthopedic implants.
Operation Hardtack. Project 6. 6. X-band radar determination of nuclear-cloud parameters
Bastian, C.W.; Robbiani, R.; Hargrave, J.
1985-09-01
The general objectives of this project were to make observations with weather Radar Set AN/CPS-9 in order to determine what characteristics and parameters of a nuclear detonation could be detected with X-band radar. The specific objectives were to obtain data that would lead to the determination of the following information relative to the nuclear cloud; rate of rise, rate of horizontal growth, maximum height, maximum diameter, stabilized height, fallout pattern due to the initial cloud formation, and range and azimuth versus time. As a result of this project, it was determined that the AN/CPS-9 radar is well suited for observations of surface or near-surface bursts, as would be expected from a comparison of its performance characteristics with those of other available radar sets.
Ridwelski, K; Meyer, F; Ebert, M; Malfertheiner, P; Lippert, H
2001-01-01
Prognosis and outcome of patients with pancreatic carcinoma is poor. The aim of the study was to investigate (1) which factors of medical history and clinical status as well as which laboratory parameters determine survival in pancreatic carcinoma and (2) whether specific data can be used as prognostic parameters or for early diagnosis of pancreatic carcinoma. In total, 287 patients with pancreatic carcinoma were enrolled in the study. In 193 subjects, only palliative treatment was possible. Survival was assessed using univariate survival probability curves by Kaplan-Meier. Comparison of patient groups with regard to survival was achieved using the log-rank test. Multivariate analysis was carried out using the Cox regression model. Overall, 22 factors, showing a significant impact on survival in pancreatic carcinoma were found, e.g., tumor-associated factors such as (1) tumor stage according to the UICC classification including TNM-based staging, grading, tumor site, and vascular infiltration; (2) preoperative habits and signs and symptoms (physical condition, pain, loss of appetite, ethanol consumption); (3) change of laboratory parameters (CA 19-9, bilirubin, prothrombin time, urea, C-reactive protein), and (4) type of intervention (surgical approach, R0/1/2 resection). Using multivariate analysis, seven factors (UICC tumor stage and site, surgical intervention including number of resected lymph nodes, chemotherapy, occurence of a carcinoma in relatives, preoperative physical condition, night sweat) were determined. In the 193 patients with palliative treatment, only ten factors (among them UICC tumor stage including the presence of metastases; data from the medical history such as physical condition, loss of appetite, and carcinoma in relatives, and laboratory parameters including prothrombin time, protein content, and aspartate aminotransferase levels) were found to be important. Chemotherapy had the strongest impact on survival which was confirmed by
López, Iván; Borzacconi, Liliana
2010-10-01
A model based on the work of Angelidaki et al. (1993) was applied to simulate the anaerobic biodegradation of ruminal contents. In this study, two fractions of solids with different biodegradation rates were considered. A first-order kinetic was used for the easily biodegradable fraction and a kinetic expression that is function of the extracellular enzyme concentration was used for the slowly biodegradable fraction. Batch experiments were performed to obtain an accumulated methane curve that was then used to obtain the model parameters. For this determination, a methodology derived from the "multiple-shooting" method was successfully used. Monte Carlo simulations allowed a confidence range to be obtained for each parameter. Simulations of a continuous reactor were performed using the optimal set of model parameters. The final steady-states were determined as functions of the operational conditions (solids load and residence time). The simulations showed that methane flow peaked at a flow rate of 0.5-0.8 Nm(3)/d/m(reactor)(3) at a residence time of 10-20 days. Simulations allow the adequate selection of operating conditions of a continuous reactor.
Determining stellar parameters of asteroseismic targets: going beyond the use of scaling relations
NASA Astrophysics Data System (ADS)
Rodrigues, Thaíse S.; Bossini, Diego; Miglio, Andrea; Girardi, Léo; Montalbán, Josefina; Noels, Arlette; Trabucchi, Michele; Coelho, Hugo Rodrigues; Marigo, Paola
2017-01-01
Asteroseismic parameters allow us to measure the basic stellar properties of field giants observed far across the Galaxy. Most of such determinations are, up to now, based on simple scaling relations involving the large frequency separation, Δν, and the frequency of maximum power, νmax. In this work, we implement Δν and the period spacing, ΔP, computed along detailed grids of stellar evolutionary tracks, into stellar isochrones and hence in a Bayesian method of parameter estimation. Tests with synthetic data reveal that masses and ages can be determined with typical precision of 5 and 19 per cent, respectively, provided precise seismic parameters are available. Adding independent information on the stellar luminosity, these values can decrease down to 3 and 10 per cent respectively. The application of these methods to NGC 6819 giants produces a mean age in agreement with those derived from isochrone fitting, and no evidence of systematic differences between RGB and RC stars. The age dispersion of NGC 6819 stars, however, is larger than expected, with at least part of the spread ascribable to stars that underwent mass-transfer events.
Kaya, S.; Merhan, O.; Kacar, C.; Colak, A.; Bozukluhan, K.
2016-01-01
Aim: The aim of this study is to determine serum ceruloplasmin levels in cows with endometritis of varying degrees of severity and to establish whether or not there is a correlation between acute phase protein (APP) levels and biochemical parameters. Material and Methods: The study was conducted with 100 Brown Swiss cows (3-8 years of age) on days 28-32 postpartum. Cows were divided into endometritis (mild, moderate, and severe endometriosis) and healthy groups based on ultrasonography, vaginoscopy, and cytological examination. Blood samples were collected from all cows. Levels of haptoglobin (Hp), serum amyloid A (SAA), ceruloplasmin, albumin, and some biochemical parameters were analyzed. Results: Hp, SAA, and ceruloplasmin levels were higher in cows with endometritis than in healthy cows (p=0.001), and the levels of these APPs increased as endometritis became more severe (p=0.001). Some significant correlations were found between APPs and the biochemical parameters that were analyzed. In conclusion, it was determined that ceruloplasmin levels increase significantly in the presence of endometritis and proportionate to the severity of endometritis. A significant correlation was found between ceruloplasmin levels and Hp and SAA levels. Conclusion: It was concluded that ceruloplasmin levels can be used in the diagnosis of endometritis as an alternative to Hp and SAA levels. PMID:27847413
Huang, Zhong; Baldwin, Philip R; Mullapudi, Srinivas; Penczek, Pawel A
2003-01-01
The current theory of image formation in electron microscopy has been semi-quantitatively successful in describing data. The theory involves parameters due to the transfer function of the microscope (defocus, spherical aberration constant, and amplitude constant ratio) as well as parameters used to describe the background and attenuation of the signal. We present empirical evidence that at least one of the features of this model has not been well characterized. Namely the spectrum of the noise background is not accurately described by a Gaussian and associated "B-factor;" this becomes apparent when one studies high-quality far-from focus data. In order to have both our analysis and conclusions free from any innate bias, we have approached the questions by developing an automated fitting algorithm. The most important features of this routine, not currently found in the literature, are (i). a process for determining the cutoff for those frequencies below which observations and the currently adopted model are not in accord, (ii). a method for determining the resolution at which no more signal is expected to exist, and (iii). a parameter-with units of spatial frequency-that characterizes which frequencies mainly contribute to the signal. Whereas no general relation is seen to exist between either of these two quantities and the defocus, a simple empirical relationship approximately relates all three.
40 CFR 86.529-98 - Road load force and inertia weight determination.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 18 2011-07-01 2011-07-01 false Road load force and inertia weight... Emission Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.529-98 Road load force and... of this section. Velocity V is in km/h and force (F) is in newtons. The forces given by the...
40 CFR 86.529-98 - Road load force and inertia weight determination.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 18 2010-07-01 2010-07-01 false Road load force and inertia weight... Emission Regulations for 1978 and Later New Motorcycles; Test Procedures § 86.529-98 Road load force and... of this section. Velocity V is in km/h and force (F) is in newtons. The forces given by the...
The determination of the operation parameters at the axial hydraulic turbine
NASA Astrophysics Data System (ADS)
Simedru, A. I.
2016-08-01
In the operating point of the monitoring moment there are assumed from process the monitoring measured parameters: the active and reactive power, upstream and downstream water levels (after the intake trash rake and at the outlet of the turbine draft tube), wicket gate and runner opening blades, the differential pressure in the spiral chamber and the hydrounit speed. So, there was established the characteristic curves obtained on analytic basis and similitude and compared with the curves measured experimentally on the hydraulic machines from the power plant. The cavitational coefficient of the machine and the cavitational coefficient of the equipment are in function of the system parameters between them especially the suction head, the runner and wicket gates blades angles of opening. The solution proposed is a method of determining the operating turbine parameters and of the cavitation, by reducing the error caused by the similitude phenomenon, using an accurate estimation of the turbine operating parameters according to the universal diagram of the turbine. The numerical obtained values permit the necessary correlation through a complex function which is able to reduce or eliminate the unwished effects of the cavitation phenomena on the hydraulic turbines of the Iron Gates power plant.
The determination of the intrinsic and extrinsic parameters of virtual camera based on OpenGL
NASA Astrophysics Data System (ADS)
Li, Suqi; Zhang, Guangjun; Wei, Zhenzhong
2006-11-01
OpenGL is the international standard of 3D image. The 3D image generation by OpenGL is similar to the shoot by camera. This paper focuses on the application of OpenGL to computer vision, the OpenGL 3D image is regarded as virtual camera image. Firstly, the imaging mechanism of OpenGL has been analyzed in view of perspective projection transformation of computer vision camera. Then, the relationship between intrinsic and extrinsic parameters of camera and function parameters in OpenGL has been analysed, the transformation formulas have been deduced. Thereout the computer vision simulation has been realized. According to the comparison between the actual CCD camera images and virtual camera images(the parameters of actual camera are the same as virtual camera's) and the experiment results of stereo vision 3D reconstruction simulation, the effectiveness of the method with which the intrinsic and extrinsic parameters of virtual camera based on OpenGL are determined has been verified.
Image parameters for maturity determination of a composted material containing sewage sludge
NASA Astrophysics Data System (ADS)
Kujawa, S.; Nowakowski, K.; Tomczak, R. J.; Boniecki, P.; Dach, J.
2013-07-01
Composting is one of the best methods for management of sewage sludge. In a reasonably conducted composting process it is important to early identify the moment in which a material reaches the young compost stage. The objective of this study was to determine parameters contained in images of composted material's samples that can be used for evaluation of the degree of compost maturity. The study focused on two types of compost: containing sewage sludge with corn straw and sewage sludge with rapeseed straw. The photographing of the samples was carried out on a prepared stand for the image acquisition using VIS, UV-A and mixed (VIS + UV-A) light. In the case of UV-A light, three values of the exposure time were assumed. The values of 46 parameters were estimated for each of the images extracted from the photographs of the composted material's samples. Exemplary averaged values of selected parameters obtained from the images of the composted material in the following sampling days were presented. All of the parameters obtained from the composted material's images are the basis for preparation of training, validation and test data sets necessary in development of neural models for classification of the young compost stage.
NASA Astrophysics Data System (ADS)
Magnoni, F.; Scognamiglio, L.; Tinti, E.; Casarotti, E.
2014-12-01
Seismic moment tensor is one of the most important source parameters defining the earthquake dimension and style of the activated fault. Moment tensor catalogues are ordinarily used by geoscientists, however, few attempts have been done to assess possible impacts of moment magnitude uncertainties upon their own analysis. The 2012 May 20 Emilia mainshock is a representative event since it is defined in literature with a moment magnitude value (Mw) spanning between 5.63 and 6.12. An uncertainty of ~0.5 units in magnitude leads to a controversial knowledge of the real size of the event. The possible uncertainty associated to this estimate could be critical for the inference of other seismological parameters, suggesting caution for seismic hazard assessment, coulomb stress transfer determination and other analyses where self-consistency is important. In this work, we focus on the variability of the moment tensor solution, highlighting the effect of four different velocity models, different types and ranges of filtering, and two different methodologies. Using a larger dataset, to better quantify the source parameter uncertainty, we also analyze the variability of the moment tensor solutions depending on the number, the epicentral distance and the azimuth of used stations. We endorse that the estimate of seismic moment from moment tensor solutions, as well as the estimate of the other kinematic source parameters, cannot be considered an absolute value and requires to come out with the related uncertainties and in a reproducible framework characterized by disclosed assumptions and explicit processing workflows.
New method for determination of the photoresist Dill parameters using spectroscopic ellipsometry
NASA Astrophysics Data System (ADS)
Boher, Pierre; Defranoux, Christophe; Piel, Jean-Philippe; Stehle, Jean-Louis P.
1999-04-01
In this paper a new method to determine photoresist Dill parameters is presented. Based on spectroscopic ellipsometry (SE) measurements, this new method is more precise than standard techniques based on transmittance measurements. Indeed, compared to photometry, SE technique is a self calibrated technique which provide directly two independent parameters Tan (Psi) and Cos (Delta) which can be used to extract directly thickness but also optical indices of a layer inside a multilayer structure. Moreover, the wavelength dependence introduces more restrictions for the data analysis since thickness and optical indices can be deduced directly in many cases. We apply this technique to different kinds of photoresist designed for 365nm and 248nm. At each wavelength ellipsometric parameters are simulated directly versus the exposure dose without any assumption on the thickness and on the index of refraction evolution. On 365nm photoresist this new method provides Dill parameters in good agreement with the standard method. On 248nm photoresist we show that the influence of the exposure is more important on the refractive index and on the thickness of the layer than on its absorption.
New method for determination of the photoresist Dill parameters using spectroscopic ellipsometry
NASA Astrophysics Data System (ADS)
Boher, Pierre; Defranoux, Christophe; Piel, Jean-Philippe; Stehle, Jean-Louis P.
1999-06-01
In this paper a new method to determine photoresist DIll parameters is presented. Based on spectroscopic ellipsometry (SE) measurements, this new method is more precise than standard techniques based on transmittance measurements. Indeed, compared to photometry, SE technique is a self calibrated technique which provide directly two independent parameters Tan (Psi) and Cos (Delta) which can be used to extract directly thickness but also optical indices of a layer inside a multilayer structure. Moreover, the wavelength dependence introduces more restrictions for the data analysis since thickness and optical indices can be deduced directly in many cases. We apply this technique to different kinds of photoresist designed for 365nm and 248nm. At each wavelength ellipsometric parameters are simulate directly versus the exposure dose without any assumption on the thickness and on the index of refraction evolution. On 365nm photoresist this new method provides Dill parameters in good agreement with the standard method. On 248nm photoresist we show that the influence of the exposure is more important on the refractive index and on the thickness of the layer than on its absorption.
Acoustical determination of the parameters governing thermal dissipation in porous media.
Olny, Xavier; Panneton, Raymond
2008-02-01
In this paper, the question of the acoustical determination of macroscopic thermal parameters used to describe heat exchanges in rigid open-cell porous media subjected to acoustical excitations is addressed. The proposed method is based on the measurement of the dynamic bulk modulus of the material, and analytical inverse solutions derived from different semiphenomenological models governing the thermal dissipation of acoustic waves in the material. Three models are considered: (1) Champoux-Allard model [J. Appl. Phys. 20, 1975-1979 (1991)] requiring knowledge of the porosity and thermal characteristic length, (2) Lafarge et al. model [J. Acoust. Soc. Am. 102, 1995-2006 (1997)] using the same parameters and the thermal permeability, and (3) Wilson model [J. Acoust. Soc. Am. 94, 1136-1145 (1993)] that requires two adjusted parameters. Except for the porosity that is obtained from direct measurement, all the other thermal parameters are derived from the analytical inversion of the models. The method is applied to three porous materials-a foam, a glass wool, and a rock wool-with very different thermal properties. It is shown that the method can be used to assess the validity of the descriptive models for a given material.
Post-processing of seismic parameter data based on valid seismic event determination
McEvilly, Thomas V.
1985-01-01
An automated seismic processing system and method are disclosed, including an array of CMOS microprocessors for unattended battery-powered processing of a multi-station network. According to a characterizing feature of the invention, each channel of the network is independently operable to automatically detect, measure times and amplitudes, and compute and fit Fast Fourier transforms (FFT's) for both P- and S- waves on analog seismic data after it has been sampled at a given rate. The measured parameter data from each channel are then reviewed for event validity by a central controlling microprocessor and if determined by preset criteria to constitute a valid event, the parameter data are passed to an analysis computer for calculation of hypocenter location, running b-values, source parameters, event count, P- wave polarities, moment-tensor inversion, and Vp/Vs ratios. The in-field real-time analysis of data maximizes the efficiency of microearthquake surveys allowing flexibility in experimental procedures, with a minimum of traditional labor-intensive postprocessing. A unique consequence of the system is that none of the original data (i.e., the sensor analog output signals) are necessarily saved after computation, but rather, the numerical parameters generated by the automatic analysis are the sole output of the automated seismic processor.
Determination of discharge parameters via OES at the Linac4 H{sup −} ion source
Briefi, S.; Fink, D.; Mattei, S.; Lettry, J.; Fantz, U.
2016-02-15
Optical emission spectroscopy (OES) measurements of the atomic Balmer series and the molecular Fulcher transition have been carried out at the Linac4 ion source in order to determine plasma parameters. As the spectroscopic system was only relatively calibrated, the data evaluation only yielded rough estimates of the plasma parameters (T{sub e} ≈ 1.2 eV, n{sub e} ≈ 1 × 10{sup 19} m{sup −3}, and n{sub H}/n{sub H{sub 2}} ≈ 0.5 at standard operational parameters). The analysis of the Fulcher transition revealed a non-thermal “hockey-stick” rotational population of the hydrogen molecules. At varying RF power, the measurements at the on-axis line of sight (LOS) showed a peak in the rotational temperatures between 25 and 40 kW of RF power, whereas a steady decrease with power was observed at a tilted LOS, indicating the presence of strong plasma parameter gradients.
Parsons, Tom
2008-01-01
Paleoearthquake observations often lack enough events at a given site to directly define a probability density function (PDF) for earthquake recurrence. Sites with fewer than 10-15 intervals do not provide enough information to reliably determine the shape of the PDF using standard maximum-likelihood techniques [e.g., Ellsworth et al., 1999]. In this paper I present a method that attempts to fit wide ranges of distribution parameters to short paleoseismic series. From repeated Monte Carlo draws, it becomes possible to quantitatively estimate most likely recurrence PDF parameters, and a ranked distribution of parameters is returned that can be used to assess uncertainties in hazard calculations. In tests on short synthetic earthquake series, the method gives results that cluster around the mean of the input distribution, whereas maximum likelihood methods return the sample means [e.g., NIST/SEMATECH, 2006]. For short series (fewer than 10 intervals), sample means tend to reflect the median of an asymmetric recurrence distribution, possibly leading to an overestimate of the hazard should they be used in probability calculations. Therefore a Monte Carlo approach may be useful for assessing recurrence from limited paleoearthquake records. Further, the degree of functional dependence among parameters like mean recurrence interval and coefficient of variation can be established. The method is described for use with time-independent and time-dependent PDF?s, and results from 19 paleoseismic sequences on strike-slip faults throughout the state of California are given.
Parsons, T.
2008-01-01
Paleoearthquake observations often lack enough events at a given site to directly define a probability density function (PDF) for earthquake recurrence. Sites with fewer than 10-15 intervals do not provide enough information to reliably determine the shape of the PDF using standard maximum-likelihood techniques (e.g., Ellsworth et al., 1999). In this paper I present a method that attempts to fit wide ranges of distribution parameters to short paleoseismic series. From repeated Monte Carlo draws, it becomes possible to quantitatively estimate most likely recurrence PDF parameters, and a ranked distribution of parameters is returned that can be used to assess uncertainties in hazard calculations. In tests on short synthetic earthquake series, the method gives results that cluster around the mean of the input distribution, whereas maximum likelihood methods return the sample means (e.g., NIST/SEMATECH, 2006). For short series (fewer than 10 intervals), sample means tend to reflect the median of an asymmetric recurrence distribution, possibly leading to an overestimate of the hazard should they be used in probability calculations. Therefore a Monte Carlo approach may be useful for assessing recurrence from limited paleoearthquake records. Further, the degree of functional dependence among parameters like mean recurrence interval and coefficient of variation can be established. The method is described for use with time-independent and time-dependent PDFs, and results from 19 paleoseismic sequences on strike-slip faults throughout the state of California are given.
Chandrasekhar, Indira; Kastenholz, Mika; Lins, Roberto D; Oostenbrink, Chris; Schuler, Lukas D; Tieleman, D Peter; van Gunsteren, Wilfred F
2003-03-01
The performance of the GROMOS96 parameter set 45A3 developed for aliphatic alkanes is tested on a bilayer of dipalmitoylphosphatidylcholine (DPPC) in water in the liquid-crystalline L(alpha) phase. Variants of the force-field parameter set as well as different sets of simulation conditions or simulation parameter sets are evaluated. In the case of the force-field parameters, the van der Waals constants for the non-bonded interaction of the ester carbonyl carbon and the partial charges and charge group definition of the phosphatidylcholine head group are examined. On the methodological side, different cut-off distances for the non-bonded interactions, use of a reaction-field force due to long-range electrostatic interactions, the frequency of removal of the centre of mass motion and the strength of the coupling of the pressure of the system to the pressure bath are tested. The area per lipid, as a measure of structure, the order parameters of the chain carbons, as a measure of membrane fluidity, and the translational diffusion of the lipids in the plane of the bilayer are calculated and compared with experimental values. An optimal set of simulation parameters for which the GROMOS96 parameter set 45A3 yields a head group area, chain order parameters and a lateral diffusion coefficient in accordance with the experimental data is listed.
NASA Astrophysics Data System (ADS)
Dag, Yusuf
Forced convection over traditional surfaces such as flat plate, cylinder and sphere have been well researched and documented. Data on forced convection over airfoil surfaces, however, remain very scanty in literature. High altitude vehicles that employ airfoils as lifting surfaces often suffer leading edge ice accretions which have tremendous negative consequences on the lifting capabilities and stability of the vehicle. One of the ways of mitigating the effect of ice accretion involves judicious leading edge convective cooling technique which in turn depends on the accuracy of convective heat transfer coefficient used in the analysis. In this study empirical investigation of convective heat transfer measurements on asymmetric airfoil is presented at different angle of attacks ranging from 0° to 20° under subsonic flow regime. The top and bottom surface temperatures are measured at given points using Senflex hot film sensors (Tao System Inc.) and used to determine heat transfer characteristics of the airfoils. The model surfaces are subjected to constant heat fluxes using KP Kapton flexible heating pads. The monitored temperature data are then utilized to determine the heat convection coefficients modelled empirically as the Nusselt Number on the surface of the airfoil. The experimental work is conducted in an open circuit-Eiffel type wind tunnel, powered by a 37 kW electrical motor that is able to generate subsonic air velocities up to around 41 m/s in the 24 square-inch test section. The heat transfer experiments have been carried out under constant heat flux supply to the asymmetric airfoil. The convective heat transfer coefficients are determined from measured surface temperature and free stream temperature and investigated in the form of Nusselt number. The variation of Nusselt number is shown with Reynolds number at various angles of attacks. It is concluded that Nusselt number increases with increasing Reynolds number and increase in angle of attack from 0
NASA Astrophysics Data System (ADS)
Lv, Wei; Li, Xiaojiao; Feng, Enmin
2014-02-01
This study is intended to provide a parameter identification method to determine the salinity of sea ice using temperature and thickness measurements. This method is particularly effective when field data are sparse and unsatisfactory due to the difficulties associated with fieldwork, especially during the polar winter. The main idea of the method is described. The salinity profile is calculated by the temperature and thickness observations, which were measured at Nella Fjord around Zhongshan Station, Antarctica during the polar night time by the 22nd Chinese Antarctic Research Expedition. Another simulation for temperature profiles during a different measurement period is performed. Results show that better simulations of the salinity and temperature distributions are possible with the estimated parameters than with Eicken's and THESCI's methods. This method will help people to understand the salinity evolution of sea ice more thoroughly.
Determination of structure parameters in strong-field tunneling ionization theory of molecules
Zhao Songfeng; Jin Cheng; Le, Anh-Thu; Lin, C. D.; Jiang, T. F.
2010-03-15
In the strong field molecular tunneling ionization theory of Tong et al. [Phys. Rev. A 66, 033402 (2002)], the ionization rate depends on the asymptotic wave function of the molecular orbital from which the electron is removed. The orbital wave functions obtained from standard quantum chemistry packages in general are not good enough in the asymptotic region. Here we construct a one-electron model potential for several linear molecules using density functional theory. We show that the asymptotic wave function can be improved with an iteration method and after one iteration accurate asymptotic wave functions and structure parameters are determined. With the new parameters we examine the alignment-dependent tunneling ionization probabilities for several molecules and compare with other calculations and with recent measurements, including ionization from inner molecular orbitals.
NASA Astrophysics Data System (ADS)
Nakano, M.; Yamashina, T.; Kumagai, H.; Inoue, H.; S.; F.
2008-12-01
Rapid determinations of the earthquake source parameters are important for early disaster response and tsunami warning issue. After the devastation of the 2004 great Sumatra-Andaman earthquake, a nationwide broadband seismograph network in Indonesia has been developed by international cooperations among Meteorological and Geophysical Agency of Indonesia (BMG), GeoForschungsZentrum Potsdam, Germany (GFZ), the China Earthquake Administration (CEA), and the National Research Institute for Earth Science and Disaster Prevention, Japan (NIED). This seismic network is intended to improve the capabilities for monitoring seismic activity and tsunami generation in Indonesia, and is a part of the Indonesia Tsunami Early Warning System (InaTEWS). We developed an automated system for rapid determinations of the earthquake source parameters called SWIFT (Source parameter determinations based on Waveform Inversion of Fourier Transformed seismograms) using data from the seismic network in Indonesia. This paper describes the SWIFT system and its performance. We also compare the obtained source parameters with those obtained by the Global Centroid Moment Tensor (GCMT) project (http://www.globalcmt.org/). The SWIFT system is based on the waveform inversion method of Nakano et al. (2008, GJI, 173, 1000-1011). In this method, waveform inversion is carried out in the frequency domain to rapidly and routinely estimate both the focal mechanism and moment function. A pure double-couple focal mechanism from a point source is assumed in order to stabilize the inversion using data from a small number of seismic stations. The fault and slip orientation angles are estimated by a grid search with respect to the dip, strike, and rake angles. The source centroid location is determined by a spatial grid search, in which we adopt adaptive grid spacings for an efficient search. The moment function is reconstructed from its bandpassed form obtained from the inversion. This system is triggered by
Schaefer, B.; Luebbecke, M.; Mann, K.
2006-05-15
The suitability of the Hartmann-Shack technique for the determination of the propagation parameters of a laser beam is faced against the well known caustic approach according to the ISO 11146 standard. A He-Ne laser (543 nm) was chosen as test beam, both in its fundamental mode as well as after intentional distortion, introducing a moderate amount of spherical aberration. Results are given for the most important beam parameters M{sup 2}, divergence, and beam widths, indicating an agreement of better than 10% and for adapted beam diameter <5%. Furthermore, the theoretical background, pros and cons, as well as some features of the software implementation for the Hartmann-Shack sensor are briefly reviewed.
Bordes, C; Fréville, V; Ruffin, E; Marote, P; Gauvrit, J Y; Briançon, S; Lantéri, P
2010-01-04
The evolution of regulation on chemical substances (i.e. REACH regulation) calls for the progressive substitution of toxic chemicals in formulations when suitable alternatives have been identified. In this context, the method of Hansen solubility parameters was applied to identify an alternative solvent less toxic than methylene chloride used in a microencapsulation process. During the process based on a multiple emulsion (W/O/W) with solvent evaporation/extraction method, the solvent has to dissolve a polymer, poly(epsilon-caprolactone) (PCL), which forms a polymeric matrix encapsulating or entrapping a therapeutic protein as the solvent is extracted. Therefore the three partial solubility parameters of PCL have been determined by a group contribution method, swelling experiments and turbidimetric titration. The results obtained allowed us to find a solvent, anisole, able to solubilize PCL and to form a multiple emulsion with aqueous solutions. A feasibility test was conducted under standard operating conditions and allowed the production of PCL microspheres.
Mogami, R; Camilo, G B; Machado, D C; Melo, P L; Carvalho, A R S
2015-01-01
Objective: To evaluate the correlations between pulmonary densitometry values and forced oscillation technique (FOT) parameters in patients with silicosis. Methods: This cross-sectional study comprised 36 non-smoker patients with silicosis and 20 matched control subjects who were submitted to FOT and multidetector CT (MDCT). Results: Compared with the control subjects, the MDCT evaluation demonstrated that patients with silicosis exhibited greater total lung mass. These patients also had larger non-aerated and poorly aerated compartments, which included nodules and scarring. Compared with the control subjects, FOT evaluation demonstrated that patients with silicosis exhibited changes in both reactive and resistive properties of the respiratory system. In these patients, there was a greater heterogeneity of the respiratory system and increased work of breathing. Significant correlations between non-aerated compartment size and FOT parameters that reflect the non-homogeneity of the respiratory system were observed. The dynamic compliance of the respiratory system was negatively correlated with non-aerated compartment size, while the impedance at 4 Hz was positively correlated with non-aerated compartment size. Conclusion: Patients with silicosis have heavier lungs. In these patients, a larger non-aerated compartment is associated with a worsening of lung function. A more significant pulmonary involvement is associated with a loss of homogeneity and increased mechanical load of the respiratory system. Advances in knowledge The findings provided by both pulmonary densitometry and FOT may add valuable information to the subjective analysis of silicosis; however, more studies are necessary to evaluate the potential use of these methods for assessing disease progression. PMID:25747897
Using Maximal Isometric Force to Determine the Optimal Load for Measuring Dynamic Muscle Power
NASA Technical Reports Server (NTRS)
Spiering, Barry A.; Lee, Stuart M. C.; Mulavara, Ajitkumar P.; Bentley, Jason R.; Nash, Roxanne E.; Sinka, Joseph; Bloomberg, Jacob J.
2009-01-01
Maximal power output occurs when subjects perform ballistic exercises using loads of 30-50% of one-repetition maximum (1-RM). However, performing 1-RM testing prior to power measurement requires considerable time, especially when testing involves multiple exercises. Maximal isometric force (MIF), which requires substantially less time to measure than 1-RM, might be an acceptable alternative for determining the optimal load for power testing. PURPOSE: To determine the optimal load based on MIF for maximizing dynamic power output during leg press and bench press exercises. METHODS: Twenty healthy volunteers (12 men and 8 women; mean +/- SD age: 31+/-6 y; body mass: 72 +/- 15 kg) performed isometric leg press and bench press movements, during which MIF was measured using force plates. Subsequently, subjects performed ballistic leg press and bench press exercises using loads corresponding to 20%, 30%, 40%, 50%, and 60% of MIF presented in randomized order. Maximal instantaneous power was calculated during the ballistic exercise tests using force plates and position transducers. Repeated-measures ANOVA and Fisher LSD post hoc tests were used to determine the load(s) that elicited maximal power output. RESULTS: For the leg press power test, six subjects were unable to be tested at 20% and 30% MIF because these loads were less than the lightest possible load (i.e., the weight of the unloaded leg press sled assembly [31.4 kg]). For the bench press power test, five subjects were unable to be tested at 20% MIF because these loads were less than the weight of the unloaded aluminum bar (i.e., 11.4 kg). Therefore, these loads were excluded from analysis. A trend (p = 0.07) for a main effect of load existed for the leg press exercise, indicating that the 40% MIF load tended to elicit greater power output than the 60% MIF load (effect size = 0.38). A significant (p . 0.05) main effect of load existed for the bench press exercise; post hoc analysis indicated that the effect of
Dietzel, Steffen; Pircher, Joachim; Nekolla, A. Katharina; Gull, Mazhar; Brändli, André W.; Pohl, Ulrich; Rehberg, Markus
2014-01-01
Determination of blood flow velocity and related hemodynamic parameters is an important aspect of physiological studies which in many settings requires fluorescent labeling. Here we show that Third Harmonic Generation (THG) microscopy is a suitable tool for label-free intravital investigations of the microcirculation in widely-used physiological model systems. THG microscopy is a non-fluorescent multi-photon scanning technique combining the advantages of label-free imaging with restriction of signal generation to a focal spot. Blood flow was visualized and its velocity was measured in adult mouse cremaster muscle vessels, non-invasively in mouse ear vessels and in Xenopus tadpoles. In arterioles, THG line scanning allowed determination of the flow pulse velocity curve and hence the heart rate. By relocating the scan line we obtained velocity profiles through vessel diameters, allowing shear rate calculations. The cell free layer containing the glycocalyx was also visualized. Comparison of the current microscopic resolution with theoretical, diffraction limited resolution let us conclude that an about sixty-fold THG signal intensity increase may be possible with future improved optics, optimized for 1200–1300 nm excitation. THG microscopy is compatible with simultaneous two-photon excited fluorescence detection. It thus also provides the opportunity to determine important hemodynamic parameters in parallel to common fluorescent observations without additional label. PMID:24933027
NASA Astrophysics Data System (ADS)
Ye, Z.; Chiao, L.
2013-12-01
Resolution analysis has been a crucial appraisal procedure in general estimation problems to help with the correct interpretation. However, complete resolution information is usually inaccessible due to the sizeable matrix inversion involved with the construction of the resolution matrix. Furthermore, there are not explicit forward kernels embedded within formulations for popular interpolation algorithms such as the kriging and the minimum curvature gridding schemes. Stochastic simulation has recently been proposed to make resolution evaluation for sizeable inverse problems tractable. We generalize the method of getting resolution information to the popular interpolation schemes. There are usually certain empirically determined tuning parameters involved in these interpolation schemes, for example, the ideal function and radius of influence for fitting the semi-variogram in the kriging method and the relative weighting of the membrane stress term in the minimum curvature gridding scheme. We show that our proposed resolution analysis not only provide the crucial spatial resolution pattern, more importantly, it helps to determine those critical tuning parameters that have been determined empirically and arbitrarily. Keywords: resolution analysis; stochastic simulation; kriging; minimum curvature gridding
NASA Astrophysics Data System (ADS)
Tang, J. S.
2011-03-01
It has been over half a century since the launch of the first artificial satellite Sputnik in 1957, which marks the beginning of the Space Age. During the past 50 years, with the development and innovations in various fields and technologies, satellite application has grown more and more intensive and extensive. This thesis is based on three major research projects which the author joined in. These representative projects cover main aspects of satellite orbit theory and application of precise orbit determination (POD), and also show major research methods and important applications in orbit dynamics. Chapter 1 is an in-depth research on analytical theory of satellite orbits. This research utilizes general transformation theory to acquire high-order analytical solutions when mean-element method is not applicable. These solutions can be used in guidance and control or rapid orbit forecast within the accuracy of 10-6. We also discuss other major perturbations, each of which is considered with improved models, in pursuit of both convenience and accuracy especially when old models are hardly applicable. Chapter 2 is POD research based on observations. Assuming a priori force model and estimation algorithm have reached their accuracy limits, we introduce empirical forces to Shenzhou-type orbit in order to compensate possible unmodeled or mismodeled perturbations. Residuals are analyzed first and only empirical force models with actual physical background are considered. This not only enhances a posteriori POD accuracy, but also considerably improves the accuracy of orbit forecast. This chapter also contains theoretical discussions on modeling of empirical forces, computation of partial derivatives and propagation of various errors. Error propagation helps to better evaluate orbital accuracy in future missions. Chapter 3 is an application of POD in space geodesy. GRACE satellites are used to obtain Antarctic temporal gravity field between 2004 and 2007. Various changes
NASA Astrophysics Data System (ADS)
Kessels, W.; Wuttke, M. W.
2007-05-01
A single well technique to determine groundwater flow values and transport parameters is presented. Multielectrode arrays are placed at the filtered casing depth by an inflatable packer or are installed on the borehole wall behind the casing.Tracer water with a higher or lower specific electrical conductivity (salinity) which is injected between the electrodes. This tracer plume then moves into the natural groundwater flow field. The observation of this movement by geoelectric logging enables the determination of the groundwater velocity and salinity. The transport parameters "effective porosity" and "dispersion length" can also be derived. The geoelectric logging uses n borehole electrodes and two grounding electrodes. Thus, either n independent two point measurements or n*(n-1)/2 pole-to-pole measurements can be conducted to obtain a full set of geoelectric measurements. This set is used to derive all electrode combinations by applying the law of superposition and reciprocity. The tracer distribution around the borehole during and after injection depends on the hydraulic and transport parameters of the aquifer and the filter sand. The transport parameter "porosity" plus the total injected tracer volume determines the tracer distribution around the borehole. The transport parameter "dispersivity" determines the abruptness of the tracer front. The method was tested by undertaking measurements in a lab aquifer filled with sand. The results are discussed and the limitations of the method are shown. Multielectrode installations behind casing were tested in situ in the two scientific boreholes CAT-LUD-1 and CAT- LUD-1A drilled in the northern part of Germany. A multielectrode packer system was designed, built and tested in these boreholes. The results are compared with colloid observations in the borehole and hydraulic triangulation in surrounded observation wells. Here, the interpretation of these in situ measurements is mainly restricted to two point geoelectric
McNamee, Cathy E; Pyo, Nayoung; Tanaka, Saaya; Vakarelski, Ivan U; Kanda, Yoichi; Higashitani, Ko
2006-03-15
In this study, we used the colloid probe atomic force microscopy (AFM) technique to investigate the adhesion force between a living cell and a silica colloid particle in a Leibovitz's L-15 medium (L-15). The L-15 liquid maintained the pharmaceutical conditions necessary to keep the cells alive in the outside environment during the AFM experiment. The force curves in such a system showed a steric repulsion in the compression force curve, due to the compression of the cells by the colloid probe, and an adhesion force in the decompression force curve, due to binding events between the cell and the probe. We also investigated for the first time how the position on the cell surface, the strength of the pushing force, and the residence time of the probe at the cell surface individually affected the adhesion force between a living cell and a 6.84 microm diameter silica colloid particle in L-15. The position of measuring the force on the cell surface was seen not to affect the value of the maximum adhesion force. The loading force was also seen not to notably affect the value of the maximum adhesion force, if it was small enough not to pierce and damage the cell. The residence time of the probe at the cell surface, however, clearly affected the adhesion force, where a longer residence time gave a larger maximum force. From these results, we could conclude that the AFM force measurements should be made using a loading force small enough not to damage the cell and a fixed residence time, when comparing results of different systems.
Methodology for Determining Optimal Exposure Parameters of a Hyperspectral Scanning Sensor
NASA Astrophysics Data System (ADS)
Walczykowski, P.; Siok, K.; Jenerowicz, A.
2016-06-01
The purpose of the presented research was to establish a methodology that would allow the registration of hyperspectral images with a defined spatial resolution on a horizontal plane. The results obtained within this research could then be used to establish the optimum sensor and flight parameters for collecting aerial imagery data using an UAV or other aerial system. The methodology is based on an user-selected optimal camera exposure parameters (i.e. time, gain value) and flight parameters (i.e. altitude, velocity). A push-broom hyperspectral imager- the Headwall MicroHyperspec A-series VNIR was used to conduct this research. The measurement station consisted of the following equipment: a hyperspectral camera MicroHyperspec A-series VNIR, a personal computer with HyperSpec III software, a slider system which guaranteed the stable motion of the sensor system, a white reference panel and a Siemens star, which was used to evaluate the spatial resolution. Hyperspectral images were recorded at different distances between the sensor and the target- from 5m to 100m. During the registration process of each acquired image, many exposure parameters were changed, such as: the aperture value, exposure time and speed of the camera's movement on the slider. Based on all of the registered hyperspectral images, some dependencies between chosen parameters had been developed: - the Ground Sampling Distance - GSD and the distance between the sensor and the target, - the speed of the camera and the distance between the sensor and the target, - the exposure time and the gain value, - the Density Number and the gain value. The developed methodology allowed us to determine the speed and the altitude of an unmanned aerial vehicle on which the sensor would be mounted, ensuring that the registered hyperspectral images have the required spatial resolution.
Determination of the elastic properties of tomato fruit cells with an atomic force microscope.
Zdunek, Artur; Kurenda, Andrzej
2013-09-11
Since the mechanical properties of single cells together with the intercellular adhesive properties determine the macro-mechanical properties of plants, a method for evaluation of the cell elastic properties is needed to help explanation of the behavior of fruits and vegetables in handling and food processing. For this purpose, indentation of tomato mesocarp cells with an atomic force microscope was used. The Young's modulus of a cell using the Hertz and Sneddon models, and stiffness were calculated from force-indentation curves. Use of two probes of distinct radius of curvature (20 nm and 10,000 nm) showed that the measured elastic properties were significantly affected by tip geometry. The Young's modulus was about 100 kPa ± 35 kPa and 20 kPa ± 14 kPa for the sharper tip and a bead tip, respectively. Moreover, large variability regarding elastic properties (>100%) among cells sampled from the same region in the fruit was observed. We showed that AFM provides the possibility of combining nano-mechanical properties with topography imaging, which could be very useful for the study of structure-related properties of fruits and vegetables at the cellular and sub-cellular scale.
Sanz-Aguilar, Ana; Anadón, José D.; Edelaar, Pim; Carrete, Martina; Tella, José Luis
2014-01-01
The dominant criterion to determine when an introduced species is established relies on the maintenance of a self-sustaining population in the area of introduction, i.e. on the viability of the population from a demographic perspective. There is however a paucity of demographic studies on introduced species, and establishment success is thus generally determined by expert opinion without undertaking population viability analyses (PVAs). By means of an intensive five year capture-recapture monitoring program (involving >12,000 marked individuals) we studied the demography of five introduced passerine bird species in southern Spain which are established and have undergone a fast expansion over the last decades. We obtained useful estimates of demographic parameters (survival and reproduction) for one colonial species (Ploceus melanocephalus), confirming the long-term viability of its local population through PVAs. However, extremely low recapture rates prevented the estimation of survival parameters and population growth rates for widely distributed species with low local densities (Estrilda troglodytes and Amandava amandava) but also for highly abundant yet non-colonial species (Estrilda astrild and Euplectes afer). Therefore, determining the establishment success of introduced passerine species by demographic criteria alone may often be troublesome even when devoting much effort to field-work. Alternative quantitative methodologies such as the analysis of spatio-temporal species distributions complemented with expert opinion deserve thus their role in the assessment of establishment success of introduced species when estimates of demographic parameters are difficult to obtain, as is generally the case for non-colonial, highly mobile passerines. PMID:25333743
Sanz-Aguilar, Ana; Anadón, José D; Edelaar, Pim; Carrete, Martina; Tella, José Luis
2014-01-01
The dominant criterion to determine when an introduced species is established relies on the maintenance of a self-sustaining population in the area of introduction, i.e. on the viability of the population from a demographic perspective. There is however a paucity of demographic studies on introduced species, and establishment success is thus generally determined by expert opinion without undertaking population viability analyses (PVAs). By means of an intensive five year capture-recapture monitoring program (involving >12,000 marked individuals) we studied the demography of five introduced passerine bird species in southern Spain which are established and have undergone a fast expansion over the last decades. We obtained useful estimates of demographic parameters (survival and reproduction) for one colonial species (Ploceus melanocephalus), confirming the long-term viability of its local population through PVAs. However, extremely low recapture rates prevented the estimation of survival parameters and population growth rates for widely distributed species with low local densities (Estrilda troglodytes and Amandava amandava) but also for highly abundant yet non-colonial species (Estrilda astrild and Euplectes afer). Therefore, determining the establishment success of introduced passerine species by demographic criteria alone may often be troublesome even when devoting much effort to field-work. Alternative quantitative methodologies such as the analysis of spatio-temporal species distributions complemented with expert opinion deserve thus their role in the assessment of establishment success of introduced species when estimates of demographic parameters are difficult to obtain, as is generally the case for non-colonial, highly mobile passerines.
Varanasi, C.; McGinn, P.J.; Pavate, V.; Kvam, E.P.
1995-09-01
Melt processing of YBa{sub 2}Cu{sub 3}O{sub {ital x}} (Y-123) with a NdBa{sub 2}Cu{sub 3}O{sub {ital x}}-123 single-crystal seed has been used to grow large single-grain Y-123 samples. Processing parameters have been varied to observe the resulting differences in the levitation force of the samples. Increased hold time above the peritectic temperature and increased undercooling temperature have been observed to be beneficial in enhancing the levitation force of the samples. The levitation force measurements have been correlated with magnetization measurements on the crushed domains.
Determination of Force Coresponding to Maximal Lactate Steady State in Tethered Swimming
PAPOTI, MARCELO; VITÓRIO, RICARDO; ARAÚJO, GUSTAVO G.; DA SILVA, ADELINO S. R.; SANTHIAGO, VANESSA; MARTINS, LUIZ E. B.; CUNHA, SÉRGIO A.; GOBATTO, CLAUDIO A.
2009-01-01
The main aim of the present investigation was to verify if the aerobic capacity (AC) measured in tethered swimming corresponds to the maximal lactate steady state (MLSS) and its correlation with 30 min and 400m free style swimming. Twenty-five swimmers were submitted to an incremental tethered swimming test (ITS) with an initial load of 20N and increments of 10N each 3min. After each stage of 3min, the athletes had 30s of interval to blood sample collections that were used to measure blood lactate concentrations ([La−]). The ACBI was determined by the abrupt increase in [La−] versus force (F). The points obtained between [La−] versus force (N) were adjusted by an exponential curve model to determine AC corresponding to 3.5mmol.l−1 (AC3.5) and 4.0mmol.l−1 (AC4.0). After these procedures, the swimmers performed maximal efforts of 30min and 400m in free style swimming. We used the distance performed in 30min and the time performed in 400m to calculate the median velocities (i.e. V30 and V400) of these protocols. After one week, in order to measure the MLSS, nine athletes performed three 30-min tethered swimming efforts with intensities of 90, 100, and 110% of ACBI. The ANOVA one-way was used to compare the ACBI, AC3.5 and AC4.0. Correlations between ACs, and between ACs and V30 and V400 (p<0.05) were determined using the Pearson’s correlation coefficient. The intensity corresponding to 100% of ACBI was similar to the MLSS. It was observed significant correlations of the aerobic capacities (i.e. ACBI, AC3.5 and AC4.0) with V30 (r>0.91) and V400 (r>0.63). According to our results, it is possible to conclude that the ACBI corresponds to the MLSS, and both the AC - individually determined - and the AC - determined using fixed blood lactate concentrations of 3.5 and 4.0mmol.l−1 - can be used to predict the mean velocity of 30min and 400m in free style swimming. In addition to that, the tethered swimming system can be used for aerobic development in places
NASA Astrophysics Data System (ADS)
Ho, Anna Y. Q.; Ness, Melissa; Hogg, David W.; Rix, Hans-Walter
2016-02-01
The Cannon is a data-driven method for determining stellar labels (physical parameters and chemical abundances) from stellar spectra in the context of vast spectroscopic surveys. It fits for the spectral model given training spectra and labels, with the polynomial order for the spectral model decided by the user, infers labels for the test spectra, and provides diagnostic output for monitoring and evaluating the process. It offers SNR-independent continuum normalization, performs well at lower signal-to-noise, and is very accurate.
Direct determination of discrete harmonic bath parameters from molecular dynamics simulations.
Walters, Peter L; Allen, Thomas C; Makri, Nancy
2017-01-15
We present a direct procedure for determining the parameters of a discrete harmonic bath modeling the influence of a complex condensed phase environment on the system of interest. The procedure employs an efficient discretization of the spectral density into modes that correspond to equal fractions of the reorganization energy. The new procedure uses directly the classical correlation function (available from molecular dynamics calculations) as input, avoiding numerical computation of the spectral density by means of a discrete Fourier transform. Convergence is obtained using a shorter time length of the correlation function, leading to significant computational savings. © 2016 Wiley Periodicals, Inc.
NASA Astrophysics Data System (ADS)
Chudzik, S.
2017-03-01
The paper presents results of research on an innovative method for determining thermal parameters of thermal insulating materials. The method is based on harmonic thermal excitations. Temperature measurements at selected points of a specimen under test are performed by means of semiconductor infrared sensors. The study also employs a 3D model of thermal diffusion. To obtain a solution of the coefficient inverse problem a method based on an artificial neural network is presented. The heat transfer coefficient on the specimen surface is estimated on the basis of a reference specimen. The validity of the adopted model of heat diffusion and the usefulness of the method proposed are verified experimentally.
Liang, Yuzhen; Kuo, Dave T F; Allen, Herbert E; Di Toro, Dominic M
2016-10-01
There is concern about the environmental fate and effects of munition constituents (MCs). Polyparameter linear free energy relationships (pp-LFERs) that employ Abraham solute parameters can aid in evaluating the risk of MCs to the environment. However, poor predictions using pp-LFERs and ABSOLV estimated Abraham solute parameters are found for some key physico-chemical properties. In this work, the Abraham solute parameters are determined using experimental partition coefficients in various solvent-water systems. The compounds investigated include hexahydro-1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX), hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine (MNX), hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), hexahydro-1,3-dinitroso-5- nitro-1,3,5-triazine (DNX), 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitrobenzene (TNB), and 4-nitroanisole. The solvents in the solvent-water systems are hexane, dichloromethane, trichloromethane, octanol, and toluene. The only available reported solvent-water partition coefficients are for octanol-water for some of the investigated compounds and they are in good agreement with the experimental measurements from this study. Solvent-water partition coefficients fitted using experimentally derived solute parameters from this study have significantly smaller root mean square errors (RMSE = 0.38) than predictions using ABSOLV estimated solute parameters (RMSE = 3.56) for the investigated compounds. Additionally, the predictions for various physico-chemical properties using the experimentally derived solute parameters agree with available literature reported values with prediction errors within 0.79 log units except for water solubility of RDX and HMX with errors of 1.48 and 2.16 log units respectively. However, predictions using ABSOLV estimated solute parameters have larger prediction errors of up to 7.68 log units. This large discrepancy is probably due to the missing R2NNO2
Determination of velocity, acceleration,and forces in the contraction of vorticella convallaria
NASA Astrophysics Data System (ADS)
Sallaq, R.; van Winkle, D. H.; Cao, J.
2003-03-01
The contractile avoidance response of the single cell vorticella convallaria is one of the fastest motions in a biological system. Previous studies of this system have been limited by the difficulty in setting up high speed camera and triggering equipment to capture the contraction, occurring over several milliseconds. Using a CMOS camera, which can continuously record and store 64x256 pel images at rep rate up to 13 kHz into 500 MB of on-board memory (Vision Research, In.-Phantom), we are able to capture the spontaneous fast contraction of the vorticella in real time. By measuring the stalk length vs. time from these recorded images , the contraction velocity and acceleration vs. time plots are determined. Using estimates of mass the contractile forces exerted by the stalk are found to be on the order of 10-10N. In addition , significant variations in all measured quantities are observed even for the same organism.
NASA Astrophysics Data System (ADS)
Peltonen, Jouko; Paajanen, Mika; Lekkala, Jukka
2000-10-01
The actuator functionality of electromechanical polypropylene films was studied using atomic force microscopy. The film carries a permanent electric charge and includes microbubbles as a result of two-dimensional stretching of the film. The thickness change of various film structures covered with electrodes was measured as a function of external voltage. The dependence was found to be nonlinear, the thickness change in the range 0.001%-0.1% of the total film thickness and affected by the internal charge density of the film. Applying a capacitor model including an air gap within the polymer layer enabled the determination of the Young's modulus, the interfacial charge density and the actuator sensitivity of the studied structures.
NASA Astrophysics Data System (ADS)
Niedzielski, Bethany; Caragianis Broadbridge, Christine; DaPonte, John S.; Gherasimova, Maria
2010-01-01
The purpose of this study was to compare the ability of several texture analysis parameters to differentiate textured samples from a smooth control on images obtained with an Atomic Force Microscope (AFM). Surface roughness plays a major role in the realm of material science, especially in integrated electronic devices. As these devices become smaller and smaller, new materials with better electrical properties are needed. New materials with smoother surface morphology have been found to have superior electrical properties than their rougher counterparts. Therefore, in many cases surface texture is indicative of the electrical properties that material will have. Physical vapor deposition techniques such as Jet Vapor Deposition and Molecular Beam Epitaxy are being utilized to synthesize these materials as they have been found to create pure and uniform thin layers. For the current study, growth parameters were varied to produce a spectrum of textured samples. The focus of this study was the image processing techniques associated with quantifying surface texture. As a result of the limited sample size, there was no attempt to draw conclusions about specimen processing methods. The samples were imaged using an AFM in tapping mode. In the process of collecting images, it was discovered that roughness data was much better depicted in the microscope's "height" mode as opposed to "equal area" mode. The AFM quantified the surface texture of each image by returning RMS roughness and the first order histogram statistics of mean roughness, standard deviation, skewness, and kurtosis. Color images from the AFM were then processed on an off line computer running NIH ImageJ with an image texture plug in. This plug in produced another set of first order statistics computed from each images' histogram as well as second order statistics computed from each images' cooccurrence matrix. The second order statistics, which were originally proposed by Haralick, include contrast, angular
Melquiades, F L; Bortoleto, G G; Marchiori, L F S; Bueno, M I M S
2012-10-31
Current methods for quality control of sugar cane are performed in extracted juice using several methodologies, often requiring appreciable time and chemicals (eventually toxic), making the methods not green and expensive. The present study proposes the use of X-ray spectrometry together with chemometric methods as an innovative and alternative technique for determining sugar cane quality parameters, specifically sucrose concentration, POL, and fiber content. Measurements in stem, leaf, and juice were performed, and those applied directly in stem provided the best results. Prediction models for sugar cane stem determinations with a single 60 s irradiation using portable X-ray fluorescence equipment allows estimating the % sucrose, % fiber, and POL simultaneously. Average relative deviations in the prediction step of around 8% are acceptable if considering that field measurements were done. These results may indicate the best period to cut a particular crop as well as for evaluating the quality of sugar cane for the sugar and alcohol industries.
NASA Technical Reports Server (NTRS)
Albert, Karen Keppler
1999-01-01
Pressure broadening and pressure-induced shift coefficients due to water and nitrogen have been determined for water vapor transitions in the CO2 region of interest to Project HALOE. The temperature dependences of the widths and shifts have also been determined for selected transitions in this region. Results have been compared with values available in the literature. The line parameters have been obtained from the analysis of room temperature recordings of the spectrum of pure water and recordings of the spectra of heated water/nitrogen mixtures. The recordings of the water vapor spectrum were obtained with Fourier Transform Spectrometers at Kitt Peak and at the Justus-Liebig-Universitat Giessen. Up to eighteen spectra have been fitted simultaneously with a multispectrum nonlinear least-squares fitting technique developed by Dr. D. Chris Benner and colleagues.
FAST INVERSION METHOD FOR DETERMINATION OF PLANETARY PARAMETERS FROM TRANSIT TIMING VARIATIONS
Nesvorny, David; Beauge, Cristian
2010-01-20
The transit timing variation (TTV) method relies on monitoring changes in timing of transits of known exoplanets. Non-transiting planets in the system can be inferred from TTVs by their gravitational interaction with the transiting planet. The TTV method is sensitive to low-mass planets that cannot be detected by other means. Here we describe a fast algorithm that can be used to determine the mass and orbit of the non-transiting planets from the TTV data. We apply our code, ttvim.f, to a wide variety of planetary systems to test the uniqueness of the TTV inversion problem and its dependence on the precision of TTV observations. We find that planetary parameters, including the mass and mutual orbital inclination of planets, can be determined from the TTV data sets that should become available in near future. Unlike the radial velocity technique, the TTV method can therefore be used to characterize the inclination distribution of multi-planet systems.
Determination of spatially dependent diffusion parameters in bovine bone using Kalman filter.
Shokry, Abdallah; Ståhle, Per; Svensson, Ingrid
2015-11-07
Although many studies have been made for homogenous constant diffusion, bone is an inhomogeneous material. It has been suggested that bone porosity decreases from the inner boundaries to the outer boundaries of the long bones. The diffusivity of substances in the bone matrix is believed to increase as the bone porosity increases. In this study, an experimental set up is used where bovine bone samples, saturated with potassium chloride (KCl), were put into distilled water and the conductivity of the water was followed. Chloride ions in the bone samples escaped out in the water through diffusion and the increase of the conductivity was measured. A one-dimensional, spatially dependent mathematical model describing the diffusion process is used. The diffusion parameters in the model are determined using a Kalman filter technique. The parameters for spatially dependent at endosteal and periosteal surfaces are found to be (12.8 ± 4.7) × 10(-11) and (5 ± 3.5) × 10(-11)m(2)/s respectively. The mathematical model function using the obtained diffusion parameters fits very well with the experimental data with mean square error varies from 0.06 × 10(-6) to 0.183 × 10(-6) (μS/m)(2).
Carroll, R.D.
1969-01-01
A statistical analysis was made of the relationship of various acoustic parameters of volcanic rocks to compressional wave velocities for data obtained in a volcanic region in Nevada. Some additional samples, chiefly granitic rocks, were also included in the study to extend the range of parameters and the variety of siliceous rock types sampled. Laboratory acoustic measurements obtained on 62 dry core samples were grouped with similar measurements obtained from geophysical logging devices at several depth intervals in a hole from which 15 of the core samples had been obtained. The effects of lithostatic and hydrostatic load on changing the rock acoustic parameters measured in the hole were noticeable when compared with the laboratory measurements on the same core. The results of the analyses determined by grouping all of the data, however, indicate that dynamic Young's, shear and bulk modulus, shear velocity, shear and compressional characteristic impedance, as well as amplitude and energy reflection coefficients may be reliably estimated on the basis of the compressional wave velocities of the rocks investigated. Less precise estimates can be made of density based on the rock compressional velocity. The possible extension of these relationships to include many siliceous rocks is suggested. ?? 1969.
Near infrared spectroscopy (NIRS) for on-line determination of quality parameters in intact olives.
Salguero-Chaparro, Lourdes; Baeten, Vincent; Fernández-Pierna, Juan A; Peña-Rodríguez, Francisco
2013-08-15
The acidity, moisture and fat content in intact olive fruits were determined on-line using a NIR diode array instrument, operating on a conveyor belt. Four sets of calibrations models were obtained by means of different combinations from samples collected during 2009-2010 and 2010-2011, using full-cross and external validation. Several preprocessing treatments such as derivatives and scatter correction were investigated by using the root mean square error of cross-validation (RMSECV) and prediction (RMSEP), as control parameters. The results obtained showed RMSECV values of 2.54-3.26 for moisture, 2.35-2.71 for fat content and 2.50-3.26 for acidity parameters, depending on the calibration model developed. Calibrations for moisture, fat content and acidity gave residual predictive deviation (RPD) values of 2.76, 2.37 and 1.60, respectively. Although, it is concluded that the on-line NIRS prediction results were acceptable for the three parameters measured in intact olive samples in movement, the models developed must be improved in order to increase their accuracy before final NIRS implementation at mills.
Cranston, P Graham; Veldhuis, Jim H; Narasimhan, Sriram; Brodland, G Wayne
2010-09-01
Although cell-level mechanical forces are crucial to tissue self-organization in contexts ranging from embryo development to cancer metastases to regenerative engineering, the absence of methods to map them over time has been a major obstacle to new understanding. Here, we present a technique for constructing detailed, dynamic maps of the forces driving morphogenetic events from time-lapse images. Forces in the cell are considered to be separable into unknown active driving forces and known passive forces, where actomyosin systems and microtubules contribute primarily to the first group and intermediate filaments and cytoplasm to the latter. A finite-element procedure is used to estimate the field of forces that must be applied to the passive components to produce their observed incremental deformations. This field is assumed to be generated by active forces resolved along user-defined line segments whose location, often along cell edges, is informed by the underlying biology. The magnitudes and signs of these forces are determined by a mathematical inverse method. The efficacy of the approach is demonstrated using noisy synthetic data from a cross section of a generic invagination and from a planar aggregate that involves two cell types, edge forces that vary with time and a neighbor change.
Forrester, S E; Yeadon, M R; King, M A; Pain, M T G
2011-03-15
Strength, or maximum joint torque, is a fundamental factor governing human movement, and is regularly assessed for clinical and rehabilitative purposes as well as for research into human performance. This study aimed to identify the most appropriate protocol for fitting a maximum voluntary torque function to experimental joint torque data. Three participants performed maximum isometric and concentric-eccentric knee extension trials on an isovelocity dynamometer and a separate experimental protocol was used to estimate maximum knee extension angular velocity. A nine parameter maximum voluntary torque function, which included angle, angular velocity and neural inhibition effects, was fitted to the experimental torque data and three aspects of this fitting protocol were investigated. Using an independent experimental estimate of maximum knee extension angular velocity gave lower variability in the high concentric velocity region of the maximum torque function compared to using dynamometer measurements alone. A weighted root mean square difference (RMSD) score function, that forced the majority (73-92%) of experimental data beneath the maximum torque function, was found to best account for the one-sided noise in experimental torques resulting from sub-maximal effort by the participants. The suggested protocol (an appropriately weighted RMSD score function and an independent estimate of maximum knee extension angular velocity) gave a weighted RMSD of between 11 and 13 Nm (4-5% of maximum isometric torque). It is recommended that this protocol be used in generating maximum voluntary joint torque functions in all torque-based modelling of dynamic human movement.
NASA Astrophysics Data System (ADS)
Wallace, D.; Ng, J. A.; Keall, P. J.; O'Brien, R. T.; Poulsen, P. R.; Juneja, P.; Booth, J. T.
2015-06-01
Kilovoltage intrafraction monitoring (KIM) utilises the kV imager during treatment for real-time tracking of prostate fiducial markers. However, its effectiveness relies on sufficient image quality for the fiducial tracking task. To guide the performance characterisation of KIM under different clinically relevant conditions, the effect of different kV parameters and patient size on image quality, and quantification of MV scatter from the patient to the kV detector panel were investigated in this study. Image quality was determined for a range of kV acquisition frame rates, kV exposure, MV dose rates and patient sizes. Two methods were used to determine image quality; the ratio of kV signal through the patient to the MV scatter from the patient incident on the kilovoltage detector, and the signal-to-noise ratio (SNR). The effect of patient size and frame rate on MV scatter was evaluated in a homogeneous CIRS pelvis phantom and marker segmentation was determined utilising the Rando phantom with embedded markers. MV scatter incident on the detector was shown to be dependent on patient thickness and frame rate. The segmentation code was shown to be successful for all frame rates above 3 Hz for the Rando phantom corresponding to a kV to MV ratio of 0.16 and an SNR of 1.67. For a maximum patient dimension less than 36.4 cm the conservative kV parameters of 5 Hz at 1 mAs can be used to reduce dose while retaining image quality, where the current baseline kV parameters of 10 Hz at 1 mAs is shown to be adequate for marker segmentation up to a patient dimension of 40 cm. In conclusion, the MV scatter component of image quality noise for KIM has been quantified. For most prostate patients, use of KIM with 10 Hz imaging at 1 mAs is adequate however image quality can be maintained and imaging dose reduced by altering existing acquisition parameters.
Hibi, N; Fujinaga, H; Ishii, K
1996-01-01
Work and power outputs during short-term, maximal exertion on a friction loaded cycle ergometer are usually calculated from the friction force applied to the flywheel. The inertia of the flywheel is sometimes taken into consideration, but the effects of internal resistances and other factors have been ignored. The purpose of this study was to estimate their effects by comparing work or power output determined from the force exerted on the pedals (pedalling force) with work or power output determined from the friction force and the moment of inertia of the rotational parts. A group of 22 male college students accelerated a cycle ergometer as rapidly as possible for 3 s. The total work output determined from the pedalling force (TWp) was significantly greater than that calculated from the friction force and the moment of inertia (TWf). Power output determined from the pedalling force during each pedal stroke (SPp) was also significantly greater than that calculated from the friction force and the moment of inertia. Percentage difference (% diff), defined by % diff = ¿(TWp - TWf)/TWf¿ x 100, ranged from 16.8% to 49.3% with a mean value of 30.8 (SD 9.1)%. It was observed that % diff values were higher in subjects with greater TWp or greater maximal SPp. These results would indicate that internal resistances and other factors, such as the deformation of the chain and the vibrations of the entire system, may have significant effects on the measurements of work and power outputs. The effects appear to depend on the magnitudes of pedalling force and pedal velocity.
NASA Astrophysics Data System (ADS)
Nishio, S.; Ogisako, E.; Denda, A.; Mitachi, T.; Hirakawa, H.
2014-12-01
In Japan, the interest in methane hydrate is increasing rapidly owing to increasing recognition of its potential as a next-generation energy resource that can replace conventional fossil fuels. To produce methane gas safely and minimize the associated environmental damage, we need to address many wide-ranging environmental issues. One such issue entails assessing seafloor stability during methane gas production. Methane hydrate binds the sand grains that make up the strata under the seafloor. It has been suggested that methane production may lead to seafloor deformation because the strata become unstable following the removal of methane hydrate. The geotechnical properties of ground have significant effects on its deformation behavior, but deep seafloors have not been thoroughly investigated yet. The world's first offshore test gas production from methane hydrate was conducted in the eastern Nankai Trough. We present geotechnical properties of the samples recovered from the gas production site; these properties were determined by means of laboratory tests. Soil index tests, consolidation tests, K0 consolidated undrained triaxial compression/extension tests and direct box shear tests were conducted for obtaining the geotechnical parameters necessary for deep seafloor stability analysis. The strength parameters corresponding to peak and residual states were determined by the reversal direct box shear tests. This study is supported by the Research Consortium for Methane Hydrate Resources in Japan. We wish to express our appreciation to the MH21 Research Consortium and Japan Oil, Gas and Metals National Corporation for their permission to use the laboratory test data.
A new methodology to determine kinetic parameters for one- and two-step chemical models
NASA Technical Reports Server (NTRS)
Mantel, T.; Egolfopoulos, F. N.; Bowman, C. T.
1996-01-01
In this paper, a new methodology to determine kinetic parameters for simple chemical models and simple transport properties classically used in DNS of premixed combustion is presented. First, a one-dimensional code is utilized to performed steady unstrained laminar methane-air flame in order to verify intrinsic features of laminar flames such as burning velocity and temperature and concentration profiles. Second, the flame response to steady and unsteady strain in the opposed jet configuration is numerically investigated. It appears that for a well determined set of parameters, one- and two-step mechanisms reproduce the extinction limit of a laminar flame submitted to a steady strain. Computations with the GRI-mech mechanism (177 reactions, 39 species) and multicomponent transport properties are used to validate these simplified models. A sensitivity analysis of the preferential diffusion of heat and reactants when the Lewis number is close to unity indicates that the response of the flame to an oscillating strain is very sensitive to this number. As an application of this methodology, the interaction between a two-dimensional vortex pair and a premixed laminar flame is performed by Direct Numerical Simulation (DNS) using the one- and two-step mechanisms. Comparison with the experimental results of Samaniego et al. (1994) shows a significant improvement in the description of the interaction when the two-step model is used.
Determination of impact parameters and efficiency of 6.8/15 caliber captive bolt guns.
Dörfler, Katharina; Troeger, Klaus; Lücker, Ernst; Schönekeß, Holger; Frank, Matthias
2014-07-01
While the morphological appearance of injuries due to powder-actuated captive bolt stunners has been extensively investigated, medicolegal literature contains, except for one work by Nadjem and Pollak (Arch Kriminol 203:91-102), no further investigations into the physical impact characteristics of these sharp-edged circular punching tools. However, basic physical parameters, such as bolt velocity, momentum, kinetic energy, and energy density, play a crucial role in the medicolegal and traumatological assessment of captive bolt stunners and the related injuries. And also, regulatory bodies demand a reliable and repeatable measurement test set-up for the determination of captive bolt stunners' impact characteristics. Therefore, it is the aim of this work to design and describe a test set-up based on one single photoelectric light barrier and to determine the impact parameters for a series of newly developed cal. 6.8/15 stunning devices. We found that bolt velocity ranges from v = 42 to 54 m/s, while momentum ranges from p = 11 to 14 Ns, and kinetic energy reaches values from E = 224 to 369 J. The efficiency of the captive bolt stunner, defined as the ratio of the kinetic energy of the stunner's bolt to the potential energy of industrial blank cartridges, also described in this work for the first time, was found to vary between 36 and 46 %.
Determination of thermoluminescence kinetic parameters of terbium-doped zirconium oxide
NASA Astrophysics Data System (ADS)
Rivera, T.; Azorín, J.; Falcony, C.; Martínez, E.; García, M.
2001-06-01
In recent years considerable importance has been attached to zirconium oxide doped with rare earth (ZrO 2 : RE) thin films due to their desirable characteristics for use in UV dosimetry. In our laboratories we have developed a method to prepare ZrO 2 : RE thin films. Dosimetric characteristics of these materials have been reported previously (Azorin et al., Radiat. Meas. 29 (1998) 315; Radiat. Prot. Dosim. 85 (1999) 317) and results of these have stimulated continued development and analysis of the thermoluminescence mechanism. Two important parameters to be determined in TL studies are the activation energy ( E) and the frequency factor ( s). This paper presents the results of determining kinetic parameters of terbium-doped zirconium oxide (ZrO 2 : Tb) thin films, exposed to 260 nm UV light, using the Lushchik (Sov. Phys. JETF 3 (1956) 390) and Chen (J. Appl. Phys. 40 (1969) 570; J. Electrochem. Soc. 166 (1969) 1254) methods. Kinetic analysis of the glow curve shows second order kinetics for both the first and second glow peaks.
Poggio, A.J.; Burke, G.J.; Pennock, S.T.
1995-01-15
This report describes the experimental and analytical program performed to determine the constitutive parameters of the reinforced concrete pad in the test facility used during the Low Power On-the-Ground portion of the NASA Boeing 757 HIRF Tests. These tests were conducted during the period September 20 to October 21, 1994 in the LESLI facility at the Phillips Laboratory, Kirtland AFB, NM. The on-the-ground tests were designed to meet several objectives including support of a flight test series and the generation of data for the validation of codes and models that could be used to predict the electromagnetic environment in transport aircraft. To satisfy these objectives, tests were to be executed in a known environment and the data compared to modeling results. A critical feature of this testing was the ``known environment`` which implies knowledge of the parameters which are critical to an effective modeling activity and which could include, among many other things, definitions of the airplane and its physical and electrical configuration, the ground upon which it sits when stationary, the fields impinging on the aircraft, and the radiating or bounding structure in the simulator. The authors would want to specify the electromagnetic characteristics of the entire space that would likely enter into a mathematical modeling effort so that the model can be made as ``close`` to physical reality as desired prior to exercising computational algorithms which might introduce their own uncertainties. Since the authors are evaluating codes used for determination of the electromagnetic environment in aircraft and since the on-the-ground test involved an airplane parked on a pad in the simulator facility, they would require a definition of the constitutive parameters of the pad.
Oldenhof, Harriëtte; Friedel, Katharina; Sieme, Harald; Glasmacher, Birgit; Wolkers, Willem F
2010-08-01
Cellular membranes are one of the primary sites of injury during freezing and thawing for cryopreservation of cells. Fourier transform infrared spectroscopy (FTIR) was used to monitor membrane phase behavior and ice formation during freezing of stallion sperm. At high subzero ice nucleation temperatures which result in cellular dehydration, membranes undergo a profound transition to a highly ordered gel phase. By contrast, low subzero nucleation temperatures, that are likely to result in intracellular ice formation, leave membrane lipids in a relatively hydrated fluid state. The extent of freezing-induced membrane dehydration was found to be dependent on the ice nucleation temperature, and showed Arrhenius behavior. The presence of glycerol did not prevent the freezing-induced membrane phase transition, but membrane dehydration occurred more gradual and over a wider temperature range. We describe a method to determine membrane hydraulic permeability parameters (E(Lp), Lpg) at subzero temperatures from membrane phase behavior data. In order to do this, it was assumed that the measured freezing-induced shift in wavenumber position of the symmetric CH(2) stretching band arising from the lipid acyl chains is proportional to cellular dehydration. Membrane permeability parameters were also determined by analyzing the H(2)O-bending and -libration combination band, which yielded higher values for both E(Lp) and Lpg as compared to lipid band analysis. These differences likely reflect differences between transport of free and membrane-bound water. FTIR allows for direct assessment of membrane properties at subzero temperatures in intact cells. The derived biophysical membrane parameters are dependent on intrinsic cell properties as well as freezing extender composition.
A new multi-wavelength model-based method for determination of enzyme kinetic parameters.
Sorouraddin, Mohammad-Hossein; Amini, Kaveh; Naseri, Abdolhossein; Vallipour, Javad; Hanaee, Jalal; Rashidi, Mohammad-Reza
2010-09-01
Lineweaver-Burk plot analysis is the most widely used method to determine enzyme kinetic parameters. In the spectrophotometric determination of enzyme activity using the Lineweaver-Burk plot, it is necessary to find a wavelength at which only the substrate or the product has absorbance without any spectroscopic interference of the other reaction components. Moreover, in this method, different initial concentrations of the substrate should be used to obtain the initial velocities required for Lineweaver-Burk plot analysis. In the present work, a multi-wavelength model-based method has been developed and validated to determine Michaelis-Menten constants for some enzyme reactions. In this method, a selective wavelength region and several experiments with different initial concentrations of the substrate are not required. The absorbance data of the kinetic assays are fitted by non-linear regression coupled to the numeric integration of the related differential equation. To indicate the applicability of the proposed method, the Michaelis-Menten constants for the oxidation of phenanthridine, 6-deoxypenciclovir and xanthine by molybdenum hydroxylases were determined using only a single initial concentration of the substrate, regardless of any spectral overlap.
Finite element determination of the forces exerted by endotracheal tubes on the upper airways.
Gustin, B; G'Sell, C; Cochelin, B; Wourms, P; Potier-Ferry, M
1996-06-01
Accidents occurring during intubations often originate in the mechanical interaction between the tube and the upper airways. A review of these accidents, including their possible complications, shows that they are mainly due to the forces exerted by the tube on the anatomical structures during the long intubation periods. The structural design of currently available tubes is presented, and the viscoelastic properties of the constituent PVC materials are analysed. It is shown how the long-term viscoelastic behaviour of the polymer can be assessed from accelerated relaxation tests in uniaxial tension at temperatures higher than the body temperature and how the variation in the relaxation modulus can be modelled through a simple constitutive equation with a minimum number of parameters. From these data, the mechanical interaction of the tubes with the trachea are computed by means of the finite element method. The relative efficiency of different types of endotracheal tubes is thus discussed and operational criteria are eventually defined for the choice of tubes in clinical situations.
Determination of μd chemistry kinetic parameters for the MuSun Experiment
NASA Astrophysics Data System (ADS)
Raha, Nandita
2014-09-01
The MuSun experiment at PSI will measure the muon doublet capture rate Λd in ultra pure deuterium gas to 1.5% precision from the measured decay-electron time distribution. This reaction cleanly determines the strength of the two-nucleon weak axial current interaction. The kinetic parameters of the μd chemistry are essential for extracting Λd, which in turn are determined from the process of muon catalyzed fusion in deuterium. This process yields 3 He recoils and 2.45 MeV monoenergetic neutrons from the reaction ddμ -->3 He + n + μ . Encoded in the time dependence of the fusion products are the ddμ molecular formation rates from the F = 1 / 2 , 3 / 2 hyperfine states (λd and λq) and the hyperfine transition rate (λqd) from the higher-energy F = 3 / 2 state to the lower-energy F = 1 / 2 state. This work concentrates on the analysis of the fusion neutrons, which are detected by an array of eight neutron detectors. Pulse shape discrimination was used to distinguish neutrons from background gamma rays. A least squared fit to the time spectrum of the fusion neutrons determines the μd chemistry kinetic parameters λqd and the ratio λq / λd. The MuSun experiment at PSI will measure the muon doublet capture rate Λd in ultra pure deuterium gas to 1.5% precision from the measured decay-electron time distribution. This reaction cleanly determines the strength of the two-nucleon weak axial current interaction. The kinetic parameters of the μd chemistry are essential for extracting Λd, which in turn are determined from the process of muon catalyzed fusion in deuterium. This process yields 3 He recoils and 2.45 MeV monoenergetic neutrons from the reaction ddμ -->3 He + n + μ . Encoded in the time dependence of the fusion products are the ddμ molecular formation rates from the F = 1 / 2 , 3 / 2 hyperfine states (λd and λq) and the hyperfine transition rate (λqd) from the higher-energy F = 3 / 2 state to the lower-energy F = 1 / 2 state. This work concentrates
Determining the Molecular Packing Arrangements on Protein Crystal Faces by Atomic Force Microscopy
NASA Technical Reports Server (NTRS)
Li, Huayu; Perozzo, Mary A.; Konnert, John H.; Nadarajan, Arunan; Pusey, Marc L.
1998-01-01
Periodic Bond Chain (PBC) analysis of the packing of tetragonal lysozyme crystals have revealed that there are two possible molecular packing arrangements for the crystal faces. The analysis also predicted that only one of these, involving the formation of helices about the 4(sub 3) axes, would prevail during crystal growth. In this study high resolution atomic force microscopy (AFM) was employed to verify these predictions for the (110) crystal face. A computer program was developed which constructs the expected AFM image for a given tip shape for each possible molecular packing arrangement. By comparing the actual AFM image with the predicted images the correct packing arrangement was determined. The prediction of an arrangement involving 4(sub 3) helices was confirmed in this manner,"while the alternate arrangement was not observed. The investigation also showed the protein molecules were packed slightly closer about the 4(sub 3) axes than in the crystallographic arrangement of the crystal interior. This study demonstrates a new approach for determining the molecular packing arrangements on protein crystal faces. It also shows the power of combining a theoretical PBC analysis with experimental high resolution AFM techniques in probing protein crystal growth processes at the molecular level.
Horta, Bruno A C; Merz, Pascal T; Fuchs, Patrick F J; Dolenc, Jozica; Riniker, Sereina; Hünenberger, Philippe H
2016-08-09
This article reports on the calibration and validation of a new GROMOS-compatible parameter set 2016H66 for small organic molecules in the condensed phase. The calibration is based on 62 organic molecules spanning the chemical functions alcohol, ether, aldehyde, ketone, carboxylic acid, ester, amine, amide, thiol, sulfide, and disulfide, as well as aromatic compounds and nucleic-acid bases. For 57 organic compounds, the calibration targets are the experimental pure-liquid density ρliq and the vaporization enthalpy ΔHvap, as well as the hydration free energy ΔGwat and the solvation free energy ΔGche in cyclohexane, at atmospheric pressure and at (or close to) room temperature. The final root-mean-square deviations (RMSD) for these four quantities over the set of compounds are 32.4 kg m(-3), 3.5 kJ mol(-1), 4.1 kJ mol(-1), and 2.1 kJ mol(-1), respectively, and the corresponding average deviations (AVED) are 1.0 kg m(-3), 0.2 kJ mol(-1), 2.6 kJ mol(-1), and 1.0 kJ mol(-1), respectively. For the five nucleic-acid bases, the parametrization is performed by transferring the final 2016H66 parameters from analogous organic compounds followed by a slight readjustment of the charges to reproduce the experimental water-to-chloroform transfer free energies ΔGtrn. The final RMSD for this quantity over the five bases is 1.7 kJ mol(-1), and the corresponding AVED is 0.8 kJ mol(-1). As an initial validation of the 2016H66 set, seven additional thermodynamic, transport, and dielectric properties are calculated for the 57 organic compounds in the liquid phase. The agreement with experiment in terms of these additional properties is found to be reasonable, with significant deviations typically affecting either a specific chemical function or a specific molecule. This suggests that in most cases, a classical force-field description along with a careful parametrization against ρliq, ΔHvap, ΔGwat, and ΔGche results in a model that appropriately describes the liquid in terms of
NASA Astrophysics Data System (ADS)
Gosch, D. L.; Dontsova, K.; Chorover, J.; Ferré, T.; Taylor, S.
2010-12-01
During military operations, a small fraction of propellant mass is not consumed during firing and is deposited onto the ground surface (Jenkins et al., 2006). Soluble propellant constituents can be released from particulate residues into the environment. Propellant constituents of interest for this study are nitroglycerine (NG), 2,4-dinitrotoluine (2,4-DNT), 2,6-dinitrotoluine (2,6-DNT), and nitroguanidine (NQ). The goal of this work is to determine fate and transport parameters for these constituents in three soils that represent a range of geographic locations and soil properties. This supports a companion study that looks at dissolution of NG, 2,4-DNT, 2,6-DNT, and NQ from fired and unfired solid propellant formulations and their transport in soils. The three soils selected for the study are Catlin silt loam (fine-silty, mixed, mesic, superactive Oxyaquic Argiudoll), Plymouth sandy loam (mesic, coated Typic Quartzipsamment), and Sassafras loam (fine loamy, siliceous, mesic Typic Hapudult). Two of these soils, Plymouth sandy loam and Sassafras loam, were collected on military installations. Linear adsorption coefficients and transformation rates of propellant constituents were determined in batch kinetic experiments. Soils were mixed with propellant constituent solutions (2 mg L-1) at 4:1 solution/soil mass ratio and equilibrated for 0, 1, 2, 6, 12, 24, 48, and 120 hr at which time samples were centrifuged and supernatant solutions were analyzed for target compounds by high performance liquid chromatography (HPLC) using U.S. EPA Method 8330b for NG, 2,4-DNT, and 2,6-DNT, and Walsh (1989) method for NQ. Adsorption and transformation of propellant constituents were determined from the decrease in solution concentration of these compounds. It was determined that all studied compounds were subjected to sorption by the solid phase and degradation. Catlin soil, with finer texture and high organic matter content, influenced solution concentration of NG, 2,4-DNT, 2,6-DNT
Determination of fiber-matrix interface failure parameters from off-axis tests
NASA Technical Reports Server (NTRS)
Naik, Rajiv A.; Crews, John H., Jr.
1993-01-01
Critical fiber-matrix (FM) interface strength parameters were determined using a micromechanics-based approach together with failure data from off-axis tension (OAT) tests. The ply stresses at failure for a range of off-axis angles were used as input to a micromechanics analysis that was performed using the personal computer-based MICSTRAN code. FM interface stresses at the failure loads were calculated for both the square and the diamond array models. A simple procedure was developed to determine which array had the more severe FM interface stresses and the location of these critical stresses on the interface. For the cases analyzed, critical FM interface stresses were found to occur with the square array model and were located at a point where adjacent fibers were closest together. The critical FM interface stresses were used together with the Tsai-Wu failure theory to determine a failure criterion for the FM interface. This criterion was then used to predict the onset of ply cracking in angle-ply laminates for a range of laminate angles. Predictions for the onset of ply cracking in angle-ply laminates agreed with the test data trends.
Vrijsen, N H; Jansen, J W; Compter, J C; Lomonova, E A
2013-07-01
A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.
NASA Astrophysics Data System (ADS)
Vrijsen, N. H.; Jansen, J. W.; Compter, J. C.; Lomonova, E. A.
2013-07-01
A measurement method is presented which identifies the magnetic hysteresis effects present in the force of linear reluctance actuators. The measurement method is applied to determine the magnetic hysteresis in the force of an E-core reluctance actuator, with and without pre-biasing permanent magnet. The force measurements are conducted with a piezoelectric load cell (Kistler type 9272). This high-bandwidth force measurement instrument is identified in the frequency domain using a voice-coil actuator that has negligible magnetic hysteresis and eddy currents. Specifically, the phase delay between the current and force of the voice-coil actuator is used for the calibration of the measurement instrument. This phase delay is also obtained by evaluation of the measured force and flux variation in the E-core actuator, both with and without permanent magnet on the middle tooth. The measured magnetic flux variation is used to distinguish the phase delay due to magnetic hysteresis from the measured phase delay between the current and the force of the E-core actuator. Finally, an open loop steady-state ac model is presented that predicts the magnetic hysteresis effects in the force of the E-core actuator.
NASA Astrophysics Data System (ADS)
Marković, Dragoljub
1993-11-01
We explore the feasibility of using LIGO and/or VIRGO gravitational-wave measurements of coalescing, neutron-star-neutron-star (NS-NS) binaries and black-hole-neutron-star (BH-NS) binaries at cosmological distances to determine the cosmological parameters of our Universe. From the observed gravitational waveforms one can infer, as direct observables, the luminosity distance D of the source and the binary's two ``redshifted masses,'' M'1≡M1(1+z) and M'2≡M2(1+z), where Mi are the actual masses and z≡Δλ/λ is the binary's cosmological redshift. Assuming that the NS mass spectrum is sharply peaked about 1.4Msolar, as binary pulsar and x-ray source observations suggest, the redshift can be estimated as z=M'NS/1.4Msolar-1. The actual distance-redshift relation D(z) for our Universe is strongly dependent on its cosmological parameters [the Hubble constant H0, or h0≡H0/100 km s-1Mpc-1, the mean mass density ρm, or density parameter Ω0≡(8π/3H20)ρm, and the cosmological constant, Λ, or λ0≡Λ/(3H20)], so by a statistical study of (necessarily noisy) measurements of D and z for a large number of binaries, one can deduce the cosmological parameters. The various noise sources that will plague such a cosmological study are discussed and estimated, and the accuracies of the inferred parameters are determined as functions of the detectors' noise characteristics, the number of binaries observed, and the neutron-star mass spectrum. The dominant source of error is the detectors' intrinsic noise, though stochastic gravitational lensing of the waves by intervening matter might significantly influence the inferred cosmological constant λ0, when the detectors reach ``advanced'' stages of development. The estimated errors of parameters inferred from BH-NS measurements can be described by the following rough analytic fits: Δh0/h0~=0.02(N/h0)(τR)-1/2 (for N/h0<~2), where N is the detector's noise level (strain/Hz) in units of the ``advanced LIGO'' noise level, R is the
NASA Astrophysics Data System (ADS)
Bayo, A.; Rodrigo, C.; Barrado, D.; Allard, F.
One of the very first steps astronomers working in stellar physics perform to advance in their studies, is to determine the most common/relevant physical parameters of the objects of study (effective temperature, bolometric luminosity, surface gravity, etc.). Different methodologies exist depending on the nature of the data, intrinsic properties of the objects, etc. One common approach is to compare the observational data with theoretical models passed through some simulator that will leave in the synthetic data the same imprint than the observational data carries, and see what set of parameters reproduce the observations best. Even in this case, depending on the kind of data the astronomer has, the methodology changes slightly. After parameters are published, the community tend to quote, praise and criticize them, sometimes paying little attention on whether the possible discrepancies come from the theoretical models, the data themselves or just the methodology used in the analysis. In this work we perform the simple, yet interesting, exercise of comparing the effective temperatures obtained via SED and more detailed spectral fittings (to the same grid of models), of a sample of well known and characterized young M-type objects members to different star forming regions and show how differences in temperature of up to 350 K can be expected just from the difference in methodology/data used. On the other hand we show how these differences are smaller for colder objects even when the complexity of the fit increases like for example introducing differential extinction. To perform this exercise we benefit greatly from the framework offered by the Virtual Observaotry.
Enhanced orbit determination filter: Inclusion of ground system errors as filter parameters
NASA Technical Reports Server (NTRS)
Masters, W. C.; Scheeres, D. J.; Thurman, S. W.
1994-01-01
The theoretical aspects of an orbit determination filter that incorporates ground-system error sources as model parameters for use in interplanetary navigation are presented in this article. This filter, which is derived from sequential filtering theory, allows a systematic treatment of errors in calibrations of transmission media, station locations, and earth orientation models associated with ground-based radio metric data, in addition to the modeling of the spacecraft dynamics. The discussion includes a mathematical description of the filter and an analytical comparison of its characteristics with more traditional filtering techniques used in this application. The analysis in this article shows that this filter has the potential to generate navigation products of substantially greater accuracy than more traditional filtering procedures.
Fourier Transform Ultrasound Spectroscopy for the determination of wave propagation parameters.
Pal, Barnana
2017-01-01
The reported results for ultrasonic wave attenuation constant (α) in pure water show noticeable inconsistency in magnitude. A "Propagating-Wave" model analysis of the most popular pulse-echo technique indicates that this is a consequence of the inherent wave propagation characteristics in a bounded medium. In the present work Fourier Transform Ultrasound Spectroscopy (FTUS) is adopted to determine ultrasonic wave propagation parameters, the wave number (k) and attenuation constant (α) at 1MHz frequency in tri-distilled water at room temperature (25°C). Pulse-echo signals obtained under same experimental conditions regarding the exciting input signal and reflecting boundary wall of the water container for various lengths of water columns are captured. The Fast Fourier Transform (FFT) components of the echo signals are taken to compute k, α and r, the reflection constant at the boundary, using Oak Ridge and Oxford method. The results are compared with existing literature values.
An adaptive method for determining an acquisition parameter t0 in a modified CPMG sequence
NASA Astrophysics Data System (ADS)
Xing, Donghui; Fan, Yiren; Hao, Jianfei; Ge, Xinmin; Li, Chaoliu; Xiao, Yufeng; Wu, Fei
2017-03-01
The modified CPMG (Carr-Purcell-Meiboom-Gill) pulse sequence is a common sequence used for measuring the internal magnetic field gradient distribution of formation rocks, for which t0 (the duration of the first window) is a key acquisition parameter. In order to obtain the optimal t0, an adaptive method is proposed in this paper. By studying the factors influencing discriminant factor σ and its variation trend using T2-G forward numerical simulation, it is found that the optimal t0 corresponds to the maximum value of σ. Then combining the constraint condition of SNR (Signal Noise Ratio) of spin echo, an optimal t0 in modified CPMG pulse sequence is determined. This method can reduce the difficulties of operating T2-G experiments. Finally, the adaptive method is verified by the results of the T2-G experiments for four water-saturated sandstone samples.
Determination of isotropic layer parameters from spatiotemporal signals of an ultrasonic array
NASA Astrophysics Data System (ADS)
Titov, S. A.; Maev, R. G.
2013-09-01
The paper discusses a method for measuring the velocities and attenuation of longitudinal and transverse ultrasonic waves and the density and thickness of the isotropic layer with an array placed in an immersion liquid parallel to the sample. The method is based on the recording of the total spatiotemporal signal of the array and its expansion into a spatial spectrum of pulse plane wave response. The ultrasonic velocity and sample thickness depend on the response delay of the plane wave in the layer from the transverse projection of the slowness vector. The density and attenuation are determined from the behavior of the amplitudes of spectral responses. To confirm this method in experiment, the parameters of a polystyrene plate have been measured using a linear 32-element array with a central frequency of 17 MHz.
NASA Astrophysics Data System (ADS)
Lei, Jun; Sun, Pengbo; Bui, Tinh Quoc
2015-01-01
To determine fracture parameters of interfacial cracks in transverse isotropic magnetoelectroelastic composites, a displacement extrapolation formula was derived. The matrix-form formula can be applicable for both material components with arbitrary poling directions. The corresponding explicit expression of this formula was obtained for each poling direction normal to the crack plane. This displacement extrapolation formula is only related to the boundary quantities of the extended crack opening displacements across crack faces, which is convenient for numerical applications, especially for BEM. Meantime, an alternative extrapolation formula based on the path-independent J-integral and displacement ratios was presented which may be more adaptable for any domain-based numerical techniques like FEM. A numerical example was presented to show the correctness of these formulae.
NASA Astrophysics Data System (ADS)
Varady, Mark; Mantooth, Brent; Pearl, Thomas; Willis, Matthew
2014-03-01
A continuum model of reactive decontamination in absorbing polymeric thin film substrates exposed to the chemical warfare agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (known as VX) was developed to assess the performance of various decontaminants. Experiments were performed in conjunction with an inverse analysis method to obtain the necessary model parameters. The experiments involved contaminating a substrate with a fixed VX exposure, applying a decontaminant, followed by a time-resolved, liquid phase extraction of the absorbing substrate to measure the residual contaminant by chromatography. Decontamination model parameters were uniquely determined using the Levenberg-Marquardt nonlinear least squares fitting technique to best fit the experimental time evolution of extracted mass. The model was implemented numerically in both a 2D axisymmetric finite element program and a 1D finite difference code, and it was found that the more computationally efficient 1D implementation was sufficiently accurate. The resulting decontamination model provides an accurate quantification of contaminant concentration profile in the material, which is necessary to assess exposure hazards.
Determination of full piezoelectric complex parameters using gradient-based optimization algorithm
NASA Astrophysics Data System (ADS)
Kiyono, C. Y.; Pérez, N.; Silva, E. C. N.
2016-02-01
At present, numerical techniques allow the precise simulation of mechanical structures, but the results are limited by the knowledge of the material properties. In the case of piezoelectric ceramics, the full model determination in the linear range involves five elastic, three piezoelectric, and two dielectric complex parameters. A successful solution to obtaining piezoceramic properties consists of comparing the experimental measurement of the impedance curve and the results of a numerical model by using the finite element method (FEM). In the present work, a new systematic optimization method is proposed to adjust the full piezoelectric complex parameters in the FEM model. Once implemented, the method only requires the experimental data (impedance modulus and phase data acquired by an impedometer), material density, geometry, and initial values for the properties. This method combines a FEM routine implemented using an 8-noded axisymmetric element with a gradient-based optimization routine based on the method of moving asymptotes (MMA). The main objective of the optimization procedure is minimizing the quadratic difference between the experimental and numerical electrical conductance and resistance curves (to consider resonance and antiresonance frequencies). To assure the convergence of the optimization procedure, this work proposes restarting the optimization loop whenever the procedure ends in an undesired or an unfeasible solution. Two experimental examples using PZ27 and APC850 samples are presented to test the precision of the method and to check the dependency of the frequency range used, respectively.
NASA Astrophysics Data System (ADS)
Lisenko, S. A.; Firago, V. A.; Kugeiko, M. M.; Kubarko, A. I.
2016-09-01
We have developed a method for on-the-fl y retrieval of the volume concentration of blood vessels, the average diameter of the blood vessels, the blood oxygenation level, and the molar concentrations of chromophores in the bulbar conjunctiva from its diffuse reflectance spectra, measured when the radiation delivery and detection channels are spatially separated. The relationship between the diffuse reflectance spectrum of the conjunctiva and its unknown parameters is described in terms of an analytical model, constructed on the basis of a highly accurate approximation analog of the Monte Carlo method. We have studied the effect of localization of hemoglobin in erythrocytes and localization of erythrocytes in the blood vessels on the power of the retrieval of structural and morphological parameters for the conjunctiva. We developed a device for obtaining video images of the conjunctiva and contactless measurements of its diffuse reflectance spectrum. By comparing simulated diffuse reflectance spectra of the conjunctiva with the experimental measurements, we established a set of chromophores which must be taken into account in the model for reproducing the experimental data within the measurement error. We observed absorption bands for neuroglobin in the experimental spectra, and provided a theoretical basis for the possibility of determining its absolute concentrations in the conjunctiva. We have shown that our method can detect low bilirubin concentrations in blood.
NASA Technical Reports Server (NTRS)
Mather, R. S.; Lerch, F. J.; Rizos, C.; Masters, E. G.; Hirsch, B.
1978-01-01
The 1977 altimetry data bank is analyzed for the geometrical shape of the sea surface expressed as surface spherical harmonics after referral to the higher reference model defined by GEM 9. The resulting determination is expressed as quasi-stationary dynamic SST. Solutions are obtained from different sets of long arcs in the GEOS-3 altimeter data bank as well as from sub-sets related to the September 1975 and March 1976 equinoxes assembled with a view to minimizing seasonal effects. The results are compared with equivalent parameters obtained from the hydrostatic analysis of sporadic temperature, pressure and salinity measurements of the oceans and the known major steady state current systems with comparable wavelengths. The most clearly defined parameter (the zonal harmonic of degree 2) is obtained with an uncertainty of + or - 6 cm. The preferred numerical value is smaller than the oceanographic value due to the effect of the correction for the permanent earth tide. Similar precision is achieved for the zonal harmonic of degree 3. The precision obtained for the fourth degree zonal harmonic reflects more closely the accuracy expected from the level of noise in the orbital solutions.
Fetal kidney length as a useful adjunct parameter for better determination of gestational age
Ugur, Mete G.; Mustafa, Aynur; Ozcan, Huseyin C.; Tepe, Neslihan B.; Kurt, Huseyin; Akcil, Emre; Gunduz, Reyhan
2016-01-01
Objectives: To determine the validity of fetal kidney length and amniotic fluid index (AFI) in labor dating. Methods: This prospective study included 180 pregnant women followed up in the outpatient clinic at the Department of Obstetrics and Gynecology, Gaziantep University, Turkey, between January 2014 and January 2015. The gestational age (GA) was estimated by early fetal ultrasound measures and last menstrual period. Routine fetal biometric parameters, fetal kidney length, and amniotic fluid index were measured. We studied the correlation between fetal kidney length, amniotic fluid index, and gestational age. Result: The mean gestational age depending on last menstrual period and early ultrasound was 31.98±4.29 (24-39 weeks). The mean kidney length was 35.66±6.61 (19-49 mm). There was a significant correlation between gestational age and fetal kidney length (r=0.947, p=0.001). However, there was a moderate negative correlation between GA and AFI. Adding fetal kidney length to the routine biometrics improved the effectiveness of the model used to estimate GA (R2=0.965 to R2=0.987). Conclusion: Gestational age can be better predicted by adding fetal kidney length to other routine parameters. PMID:27146616
Determination of stress parameters for eight well-recorded earthquakes in eastern North America
Boore, D.M.; Campbell, K.W.; Atkinson, G.M.
2010-01-01
We determined the stress parameter, Δσ, for the eight earthquakes studied by Atkinson and Boore (2006), using an updated dataset and a revised point-source stochastic model that captures the effect of a finite fault. We consider four geometrical-spreading functions, ranging from 1/R at all distances to two- or three-part functions. The Δσ values are sensitive to the rate of geometrical spreading at close distances, with 1/R1.3 spreading implying much higher Δσ than models with 1/R spreading. The important difference in ground motions of most engineering concern, however, arises not from whether the geometrical spreading is 1/R1.3 or 1/R at close distances, but from whether a region of flat or increasing geometrical spreading at intermediate distances is present, as long as Δσ is constrained by data that are largely at distances of 100 km–800 km. The simple 1/R model fits the sparse data for the eight events as well as do more complex models determined from larger datasets (where the larger datasets were used in our previous ground-motion prediction equations); this suggests that uncertainty in attenuation rates is an important component of epistemic uncertainty in ground-motion modeling. For the attenuation model used by Atkinson and Boore (2006), the average value of Δσ from the point-source model ranges from 180 bars to 250 bars, depending on whether or not the stress parameter from the 1988 Saguenay earthquake is included in the average. We also find that Δσ for a given earthquake is sensitive to its moment magnitude M, with a change of 0.1 magnitude units producing a factor of 1.3 change in the derived Δσ.
Determining the mechanism and parameters of hydrate formation and loss in glucose.
Scholl, Sarah K; Schmidt, Shelly J
2014-11-01
Water-solid interactions are known to play a major role in the chemical and physical stability of food materials. Despite its extensive use throughout the food industry, the mechanism and parameters of hydrate formation and loss in glucose are not well characterized. Hydrate formation in alpha-anhydrous glucose (α-AG) and hydrate loss in glucose monohydrate (GM) were studied under equilibrium conditions at various relative humidity (RH) values using saturated salt slurries for 1 y. The mechanism of hydrate formation and hydrate loss were determined through mathematical modeling of Dynamic Vapor Sorption data and Raman spectroscopy was used to confirm the mechanisms. The critical temperature for hydrate loss in GM was determined using thermogravimetric analysis (TGA). The moisture sorption profiles of α-AG and GM were also studied under dynamic conditions using an AquaSorp Isotherm Generator. Hydrate formation was observed at and above 68% RH at 25 °C and the conversion of α-AG to GM can best be described as following a nucleation mechanism, however, diffusion and/or geometric contraction mechanisms were also observed by Raman spectroscopy subsequent to the coalescence of initial nucleation sites. Hydrate loss was observed to occur at and below 11% RH at 25 °C during RH storage and at 70 °C during TGA. The conversion of GM to α-AG follows nucleation and diffusion mechanisms. Hydrate formation was evident under dynamic conditions in α-AG and GM prior to deliquescence. This research is the first to report hydrate formation and loss parameters for crystalline α-AG and GM during extended storage at 25 ˚C.
Kujawska, Tamara; Nowicki, Andrzej; Lewin, Peter A
2011-12-01
This work addresses the difficulties in the measurements of the nonlinear medium parameter B/A and presents a modification of the finite amplitude method (FAM), one of the accepted procedures to determine this parameter. The modification is based on iterative, hybrid approach and entails the use of the versatile and comprehensive model to predict distortion of the pressure-time waveform and its subsequent comparison with the one experimentally determined. The measured p-t waveform contained at least 18 harmonics generated by 2.25 MHz, 29 mm effective diameter, single element, focused PZT source (f-number 3.5) and was recorded by Sonora membrane hydrophone calibrated in the frequency range 1-40 MHz. The hydrophone was positioned coaxially at the distal end of the specially designed, two-section assembly comprising of one, fixed length (60mm), water-filled cylindrical container and the second, variable length (60-120 mm) container that was filled with unknown medium. The details of the measurement chamber are described and the reasons for this specific design are analyzed. The data were collected with the variable length chamber filled with 1.3-butanediol, which was used as a close approximation of tissue mimicking phantom. The results obtained provide evidence that a novel combination of the FAM with the semi-empirical nonlinear propagation model based on the hyperbolic operator is capable of reducing the overall uncertainty of the B/A measurements as compared to those reported in the literature. The overall uncertainty of the method reported here was determined to be ±2%, which enhances the confidence in the numerical values of B/A measured for different, clinically relevant media. Optimization of the approach is also discussed and it is shown that it involves an iterative procedure that entails a careful selection of the acoustic source and its geometry and the axial distance over which the measurements need to be performed. The optimization also depends
NASA Astrophysics Data System (ADS)
Tsuda, K.; Archuleta, R.
2003-12-01
The data from the Yokohama high-density accelerometer array have been used to try to separate path, source and site effects. The Yokohama array has 150 surface accelerometers and 9 borehole accelerometers located in a 20 km x 20 km region. The main objective of this study is to measure the variance of site effects for closely spaced sites on similar surficial geology. Since 1998, the array has recorded more than 30 earthquakes, 13 of these events were recorded at all borehole stations, and selected for our analysis (9 deep events and 4 shallow events). Using the data from these 13 events we estimate the seismic moment and corner frequency for each event, Qo, frequency dependence of Q, and the frequency dependent site effect. We use Boatwright's (1978) representation of the omega-squared spectrum for the source. The quality factor is assumed to be constant for frequencies less than 1.0 Hz while having a power law relation for frequencies greater than 1.0 Hz. Using a Heat Bath algorithm, we estimate the parameters for the source and path using only the borehole stations. Initially the borehole response is assumed to be unity and path attenuation fixed while Mo is determined by inverting the data for f… 1Hz. The difference between the observed and predicted spectrum at each borehole is then used as the site response of the borehole records and Qo, Q(f) and fc are determined by inverting the borehole data from the 9 deep events, keeping Mo fixed to the previously determined values. We iterate until changes in the residuals between observed and predicted spectra are negligible. Once stable values of Mo, fc and Q(f) are obtained, we invert only the source parameters (Mo and fc) using the 9 borehole stations for each of the 9 events individually. The same procedure is applied for 4 shallow events. Knowing Mo, fc, and Q(f), we can then determine the site response for the 150 surface stations by averaging the ratio between predicted and observed amplitude spectra. The Q
Determination of electric parameters of cell membranes by a dielectrophoresis method.
Marszalek, P; Zielinsky, J J; Fikus, M; Tsong, T Y
1991-01-01
Marszalek, P., J. J. Zielinsky, and M. Fikus (1989. Bioelectrochem. Bioenerg. 22:289-298) have described a novel design for measuring the complete dielectrophoretic spectrum of a single cell. From the analysis of the dielectrophoretic spectrum, the membrane conductivity, sigma membr, and the membrane dielectric permittivity, epsilon membr, of the cell may be determined according to the theory of dielectrophoresis described by Sauer, F. A. (1985. Interactions between Electromagnetic Field and Cells. A. Chiabrera, C. Nicolini, and H.P. Schwan, editors. Plenum Publishing Corp., New York. 181-202). At Fo, the net force experienced by a single shell sphere in a nonuniform periodic field is zero, and the sphere ceases to move in the field. In other words, at Fo, the effective polarizability, chi eff, of the sphere (the polarizability of sphere minus the polarizability of the medium) is equal to zero. For biological cells in high conductivity medium, e.g., the isotonic saline, sigma membr falls below 2 x 10(-6) S m-1, where Fo becomes insensitive to sigma membr, and the method becomes impractical. In a low conductivity medium, 0.3 M sucrose, sigma membr of cells is generally higher and the method may be applied. Assuming a membrane thickness of 9 nm, epsilon membr of Neurospora crassa slime cells was determined to be in the range of 8.3-9.4 epsilon o, and of myeloma Tib9 to be 9.4 epsilon o, epsilon o being the dielectric permittivity of the free space. The values for the slime cells were compared with values obtained by the dielectric spectroscopy method which measures average values for cells in suspension. PMID:1831052
Molecular Line Parameters Precisely Determined by a Cavity Ring-Down Spectrometer
NASA Astrophysics Data System (ADS)
Hu, Shui-Ming; Tan, Yan; Wang, Jin; Lu, Yan; Cheng, Cunfeng; Sun, Yu Robert; Liu, An-Wen
2015-06-01
A cavity ring-down spectrometer calibrated with a set of precise atomic lines was built to retrieve precise line parameters in the near infrared.~[1,2] The spectrometer allows us to detect absorptions with a sensitivity of 10-11~cm-1 and a spectral precision up to 10-6~cm-1. Ro-vibrational lines in the second overtone of H_2 have been observed, including the extremely weak S_3(5) line with a line intensity less than 1× 10-30cm/molecule, which is among the weakest molecular lines detected by absorption in the gas phase. The absolute line positions of H_2 agree well with the high-level quantum chemical calculations including relativistic and QED corrections, with the deviation being less than 5× 10-4~cm-1.~[3,4] A quantitative study has also been carried out on the ν_1+5ν_3 band of CO_2.~[5] It was the first CO_2 band observed 80 years ago in the spectrum of Venus. We determined the line positions with an accuracy of 3× 10-5~cm-1, two orders of magnitude better than previous studies. Similar studies have been carried out to determine the line parameters of H_2O~[6] and CO~[7] in the spectral regions near 0.8~μm. The spectroscopic parameters can be used in varies studies, from the atmospheres of the earth-like planets to the test of fundamental physics. References [1] H. Pan, et al. Rev. Sci. Instrum. 82, 103110 (2011). [2] C.-F. Cheng, Opt. Expr. 20, 9956 (2012). [3] C.-F. Cheng, et al. Phys. Rev. A 85, 024501 (2012). [4] y. Tan, et al. J. Mol. Spectrosc. 300, 60 (2014). [5] Y. Lu, et al. Astrophys. J. 775, 71 (2013). [6] Y. Lu, et al. JQSRT 118, 96 (2013). [7] Y. Tan, et al. ``Ro-vibrational analysis of the fifth overtone of CO at 802~nm'', under preparation.
Collision forces for compliant projectiles
NASA Technical Reports Server (NTRS)
Grady, Joseph E.
1990-01-01
Force histories resulting from the impact of compliant projectiles were determined experimentally. A long instrumented rod was used as the target, and the impact force was calculated directly from the measured strain response. Results from a series of tests on several different sized impactors were used to define four dimensionless parameters that determine, for a specified impactor velocity and size, the amplitude, duration, shape, and impulse of the impact force history.
Albedo of the south pole on Mars determined by topographic forcing of atmosphere dynamics
Colaprete, A.; Barnes, J.R.; Haberle, R.M.; Hollingsworth, J.L.; Kieffer, H.H.; Titus, T.N.
2005-01-01
The nature of the martian south polar cap has remained enigmatic since the first spacecraft observations. In particular, the presence of a perennial carbon dioxide ice cap, the formation of a vast area of black 'slab ice' known as the Cryptic region and the asymmetric springtime retreat of the cap have eluded explanation. Here we present observations and climate modelling that indicate the south pole of Mars is characterized by two distinct regional climates that are the result of dynamical forcing by the largest southern impact basins, Argyre and Hellas. The style of surface frost deposition is controlled by these regional climates. In the cold and stormy conditions that exist poleward of 60?? S and extend 180?? in longitude west from the Mountains of Mitchel (???30?? W), surface frost accumulation is dominated by precipitation. In the opposite hemisphere, the polar atmosphere is relatively warm and clear and frost accumulation is dominated by direct vapour deposition. It is the differences in these deposition styles that determine the cap albedo.
Albedo of the South Pole on Mars Determined by Topographic Forcing of Atmosphere Dynamics
NASA Technical Reports Server (NTRS)
Colaprete, Anthony; Barnes, Jeffrey R.; Haberle, Robert M.; Hollingsworth, Jeffery L.; Kleffer, Hugh H.; Titus, Timothy N.
2005-01-01
The nature of the martian south polar cap has remained enigmatic since the first spacecraft observations. In particular, the presence of a perennial carbon dioxide ice cap, the formation of a vast area of black slab ice known as the Cryptic region and the asymmetric springtime retreat of the cap have eluded explanation. Here we present observations and climate modelling that indicate the south pole of Mars is characterized by two distinct regional climates that are the result of dynamical forcing by the largest southern impact basins, Argyre and Hellas. The style of surface frost deposition is controlled by these regional climates. In the cold and stormy conditions that exist poleward of 60 degrees S and extend 180 degrees in longitude west from the Mountains of Mitchel (about 30 degrees W), surface frost accumulation is dominated by precipitation. In the opposite hemisphere, the polar atmosphere is relatively warm and clear and frost accumulation is dominated by direct vapour deposition. It is the differences in these deposition styles that determine the cap albedo.
Alan, Bircan; Utangaç, Mazhar; Göya, Cemil; Dağgülli, Mansur
2016-01-01
Background The aim of this study was to investigate the potential contribution of acoustic radiation force impulse (ARFI) elastography to the determination of the severity of benign prostate hypertrophy (BPH) by performing shear wave velocity (SWV) measurements of the prostate using ARFI technology. Material/Methods Sixty BPH patients and 40 healthy volunteers were included in this study. SWV measurements of the prostate were performed by transabdominal ultrasonography (US), both in the BPH patients and control subjects. The BPH patients also underwent uroflowmetry measurements. Using the International Prostate Symptom Score (IPSS), the BPH patients were divided into two subgroups, a mild-to-moderate BPH group and a severe BPH group, to compare SWV values. Results The BPH patients had higher SWV values for the central area of the prostate compared to the control subjects (2.52±0.59 m/s and 1.47±0.42 m/s, p<0.01). The SWV values of the central area of prostate were higher in the severe BPH group compared to the mild-to-moderate BPH group (2.62±0.58 and 2.25±0.55, p=0.02). Conclusions Our ARFI elastography results indicated that the central prostate SWV values of BPH patients were significantly higher relative to those of a healthy control group. The central prostate SWV values increased in proportion to the increased severity of BPH. Measurement of SWV by ARFI technology constitutes a non-invasive alternative to other methods for the determination of BPH severity. PMID:27876713
Automatic determination of primary electron beam parameters in Monte Carlo simulation
Pena, Javier; Gonzalez-Castano, Diego M.; Gomez, Faustino; Sanchez-Doblado, Francisco; Hartmann, Guenther H.
2007-03-15
In order to obtain realistic and reliable Monte Carlo simulations of medical linac photon beams, an accurate determination of the parameters that define the primary electron beam that hits the target is a fundamental step. In this work we propose a new methodology to commission photon beams in Monte Carlo simulations that ensures the reproducibility of a wide range of clinically useful fields. For such purpose accelerated Monte Carlo simulations of 2x2, 10x10, and 20x20 cm{sup 2} fields at SSD=100 cm are carried out for several combinations of the primary electron beam mean energy and radial FWHM. Then, by performing a simultaneous comparison with the correspondent measurements for these same fields, the best combination is selected. This methodology has been employed to determine the characteristics of the primary electron beams that best reproduce a Siemens PRIMUS and a Varian 2100 CD machine in the Monte Carlo simulations. Excellent agreements were obtained between simulations and measurements for a wide range of field sizes. Because precalculated profiles are stored in databases, the whole commissioning process can be fully automated, avoiding manual fine-tunings. These databases can also be used to characterize any accelerators of the same model from different sites.
A borehole fluid conductivity logging method for the determination of fracture inflow parameters
Tsang, Chin-Fu
1987-10-01
It is of much current interest to determine the flow characteristics of fractures intersecting a wellbore to provide data in the estimation of the hydrologic behavior of fractured rocks. The fluid inflow rates from the fractures into the wellbore are important quantities to measure. Often these inflows are at very low rates. One often finds that only a few percent of the fractures identified by core inspection and geophysical logging are water-conducting fractures, the rest being closed, clogged, or isolated from the water flow system. A new procedure is proposed and a corresponding method of analysis developed to locate water-conducting fractures and obtain fracture inflow parameters by means of a time sequence of electric conductivity logs of the borehole fluid. The physical basis of the analysis method is discussed. The procedure is applied to an existing set of data, which shows initiation and growth of nine conductivity peaks in a 900-m section of a 1690-m borehole, corresponding to nine water-conducting fractures intersecting the borehole. We are able to match all nine peaks and determine the flow rates from these fractures. 16 refs., 28 figs., 5 tabs.
NASA Technical Reports Server (NTRS)
Born, G. H.
1974-01-01
Mariner 9 Doppler tracking data and television photographs of Deimos and Phobos were analyzed to determine the gravity field, mass, and spin-axis direction of Mars and the natural satellite orbits. The solutions agree with previously published results. Radio data consisted of an apoapsis state vector for each of revolutions 5-195 obtained from one-revolution fits of Doppler data. Optical data consisted of TV photographs of Phobos and Deimos taken between revolutions 25 and 221. A first-order analytical theory, extended to include dominant second-order resonance effects on the Mariner 9 orbit, was used to calculate the motion of the spacecraft, Deimos, and Phobos. The feasibility of combining radio and optical data in long-arc solutions for accurate determination of orbits and physical parameters is demonstrated. The analytical theory developed for the evolution of a highly eccentric orbit in shallow resonance is accurate to plus or minus 1 km in the apoapsis state vector of Mariner 9 over a period of 200 revolutions.
Duffy, M C; Blitzer, B L; Boyer, J L
1983-01-01
To determine directly the driving forces for bile acid entry into the hepatocyte, the uptake of [3H]taurocholic acid into rat liver plasma membrane vesicles was studied. The membrane preparation contained predominantly right-side-out vesicles, and was highly enriched in plasma membrane marker enzymes. The uptake of taurocholate at equilibrium was inversely related to medium osmolarity, indicating transport into an osmotically sensitive space. In the presence of an inwardly directed sodium gradient (NaCl or sodium gluconate), the initial rate of uptake was rapid and taurocholate was transiently accumulated at a concentration twice that at equilibrium (overshoot). Other inwardly directed cation gradients (K+, Li+, choline+) or the presence of sodium in the absence of a gradient (Na+ equilibrated) resulted in a slower initial uptake rate and did not sustain an overshoot. Bile acids inhibited sodium-dependent taurocholate uptake, whereas bromsulphthalein inhibited both sodium-dependent and sodium-independent uptake and D-glucose had no effect on uptake. Uptake was temperature dependent, with maximal overshoots occurring at 25 degrees C. Imposition of a proton gradient across the vesicle (pHo less than pHi) in the absence of a sodium gradient failed to enhance taurocholate uptake, indicating that double ion exchange (Na+-H+, OH- -anion) is unlikely. Creation of a negative intravesicular potential by altering accompanying anions or by valinomycin-induced K+-diffusion potentials did not enhance taurocholate uptake, suggesting an electroneutral transport mechanism. The kinetics of taurocholate uptake demonstrated saturability with a Michaelis constant at 52 microM and maximum velocity of 4.5 nmol X mg-1 X protein X min-1. These studies provide definitive evidence for a sodium gradient-dependent, carrier-mediated, electrically neutral transport mechanism for hepatic taurocholate uptake. These findings are consistent with a model for bile secretion in which the basolateral
Pervushin, Yu.S.; Valiev, R.S.
1987-03-01
An installation and a method for investigating thermal forces and strains in structural elements type rods, plates and panels of composite polymer materials subjected to one-sided heating are presented. A diagram of the installation for investigating the thermal forces in structural elements of heat-insulating materials subjected to one-sided heating is shown. The dependences of the support membrane forces and bending moments in the rod on the temperature in one-sided heating were established. The nature of the change of the thermal forces depends on the speed and depth of penetration of the front of temperatures exceeding the temperature of onset of destruction into the section of the material. During cooling, the tensile forces and bending moments continue to increase.
Sensitivity Analysis of the USLE Soil Erodibility Factor to Its Determining Parameters
NASA Astrophysics Data System (ADS)
Mitova, Milena; Rousseva, Svetla
2014-05-01
Soil erosion is recognized as one of the most serious soil threats worldwide. Soil erosion prediction is the first step in soil conservation planning. The Universal Soil Loss Equation (USLE) is one of the most widely used models for soil erosion predictions. One of the five USLE predictors is the soil erodibility factor (K-factor), which evaluates the impact of soil characteristics on soil erosion rates. Soil erodibility nomograph defines K-factor depending on soil characteristics, such as: particle size distribution (fractions finer that 0.002 mm and from 0.1 to 0.002 mm), organic matter content, soil structure and soil profile water permeability. Identifying the soil characteristics, which mostly influence the K-factor would give an opportunity to control the soil loss through erosion by controlling the parameters, which reduce the K-factor value. The aim of the report is to present the results of analysis of the relative weight of these soil characteristics in the K-factor values. The relative impact of the soil characteristics on K-factor was studied through a series of statistical analyses of data from the geographic database for soil erosion risk assessments in Bulgaria. Degree of correlation between K-factor values and the parameters that determine it was studied by correlation analysis. The sensitivity of the K-factor was determined by studying the variance of each parameter within the range between minimum and maximum possible values considering average value of the other factors. Normalizing transformation of data sets was applied because of the different dimensions and the orders of variation of the values of the various parameters. The results show that the content of particles finer than 0.002 mm has the most significant relative impact on the soil erodibility, followed by the content of particles with size from 0.1 mm to 0.002 mm, the class of the water permeability of the soil profile, the content of organic matter and the aggregation class. The
The Determination of Forces and Moments on a Gimballed SRM Nozzle Using a Cold Flow Model
NASA Technical Reports Server (NTRS)
Whitesides, R. Harold; Bacchus, David L.; Hengel, John E.
1994-01-01
The Solid Rocket Motor Air Flow Facility (SAF) at NASA Marshall Space Flight Center was used to characterize the flow in the critical aft end and nozzle of a solid propellant rocket motor (SRM) as part of the design phase of development. The SAF is a high pressure, blowdown facility which supplies a controlled flow of air to a subscale model of the internal port and nozzle of a SRM to enable measurement and evaluation of the flow field and surface pressure distributions. The ASRM Aft Section/Nozzle Model is an 8 percent scale model of the 19 second burn time aft port geometry and nozzle of the Advanced Solid Rocket Motor, the now canceled new generation space Shuttle Booster. It has the capability to simulate fixed nozzle gimbal angles of 0, 4, and 8 degrees. The model was tested at full scale motor Reynolds Numbers with extensive surface pressure instrumentation to enable detailed mapping of the surface pressure distributions over the nozzle interior surface, the exterior surface of the nozzle nose and the surface of the simulated propellant grain in the aft motor port. A mathematical analysis and associated numerical procedure were developed to integrate the measured surface pressure distributions to determine the lateral and axial forces on the moveable section of the nozzle, the effective model thrust and the effective aerodynamic thrust vector (as opposed to the geometric nozzle gimbal angle). The nozzle lateral and axial aerodynamic loads and moments about the pivot point are required for design purposes and require complex, three dimensional flow analyses. The alignment of the thrust vector with the nozzle geometric centerline is also a design requirement requiring three dimensional analyses which were supported by this experimental program. The model was tested with all three gimbal angles at three pressure levels to determine Reynolds number effects and reproducibility. This program was successful in demonstrating that a measured surface pressure
Determination of Experimental Fuel Rod Parameters using 3D Modelling of PCMI with MPS Defect
Casagranda, Albert; Spencer, Benjamin Whiting; Pastore, Giovanni; Novascone, Stephen Rhead; Hales, Jason Dean; Williamson, Richard L; Martineau, Richard Charles
2016-05-01
An in-reactor experiment is being designed in order to validate the pellet-cladding mechanical interaction (PCMI) behavior of the BISON fuel performance code. The experimental parameters for the test rod being placed in the Halden Research Reactor are being determined using BISON simulations. The 3D model includes a missing pellet surface (MPS) defect to generate large local cladding deformations, which should be measureable after typical burnup times. The BISON fuel performance code is being developed at Idaho National Laboratory (INL) and is built on the Multiphysics Object-Oriented Simulation Environment (MOOSE) framework. BISON supports both 2D and 3D finite elements and solves the fully coupled equations for solid mechanics, heat conduction and species diffusion. A number of fuel performance effects are included using models for swelling, densification, creep, relocation and fission gas production & release. In addition, the mechanical and thermal contact between the fuel and cladding is explicitly modelled using a master-slave based contact algorithm. In order to accurately predict PCMI effects, the BISON code includes the relevant physics involved and provides a scalable and robust solution procedure. The depth of the proposed MPS defect is being varied in the BISON model to establish an optimum value for the experiment. The experiment will be interrupted approximately every 6 months to measure cladding radial deformation and provide data to validate BISON. The complete rodlet (~20 discrete pellets) is being simulated using a 180° half symmetry 3D model with MPS defects at two axial locations. In addition, annular pellets will be used at the top and bottom of the pellet stack to allow thermocouples within the rod to measure the fuel centerline temperature. Simulation results will be presented to illustrate the expected PCMI behavior and support the chosen experimental design parameters.
Ballak, Sam B; Degens, Hans; de Haan, Arnold; Jaspers, Richard T
2014-03-01
Human aging is associated with a progressive decline in skeletal muscle mass and force generating capacity, however the exact mechanisms underlying these changes are not fully understood. Rodents models have often been used to enhance our understanding of mechanisms of age-related changes in human skeletal muscle. However, to what extent age-related alterations in determinants of muscle force generating capacity observed in rodents resemble those in humans has not been considered thoroughly. This review compares the effect of aging on muscle force generating determinants (muscle mass, fiber size, fiber number, fiber type distribution and muscle specific tension), in men and male rodents at similar relative age. It appears that muscle aging in male F344*BN rat resembles that in men most; 32-35-month-old rats exhibit similar signs of muscle weakness to those of 70-80-yr-old men, and the decline in 36-38-month-old rats is similar to that in men aged over 80 yrs. For male C57BL/6 mice, age-related decline in muscle force generating capacity seems to occur only at higher relative age than in men. We conclude that the effects on determinants of muscle force differ between species as well as within species, but qualitatively show the same pattern as that observed in men.
NASA Astrophysics Data System (ADS)
Ravindranath, V. M.; Basavarajappa, G. S. Shiva Shankar S.; Suresh, R.
2016-09-01
In aluminium matrix composites, reinforcement of hard ceramic particle present inside the matrix which causes tool wear, high cutting forces and poor surface finish during machining. This paper focuses on effect of cutting parameters on thrust force, surface roughness and burr height during drilling of MMCs. In the present work, discuss the influence of spindle speed and feed rate on drilling the pure base alloy (Al-2219), mono composite (Al- 2219+8% B4C) and hybrid composite (Al-2219+8%B4C+3%Gr). The composites were fabricated using liquid metallurgy route. The drilling experiments were conducted by CNC machine with TiN coated HSS tool, M42 (Cobalt grade) and carbide tools at various spindle speeds and feed rates. The thrust force, surface roughness and burr height of the drilled hole were investigated in mono composite and hybrid composite containing graphite particles, the experimental results show that the feed rate has more influence on thrust force and surface roughness. Lesser thrust force and discontinuous chips were produced during machining of hybrid composites when compared with mono and base alloy during drilling process. It is due to solid lubricant property of graphite which reduces the lesser thrust force, burr height and lower surface roughness. When machining with Carbide tool at low feed and high speeds good surface finish was obtained compared to other two types of cutting tool materials.
Kamenev, Yu E; Masalov, S A; Filimonova, A A
2005-04-30
A method is proposed and a device is described for determining the electrodynamic parameters of one-dimensional wire gratings in the submillimetre range. The grating under study was used as the output mirror of the laser. The transmission coefficient and the phase shift are determined experimentally for several gratings with different parameters at a wavelength of 337 {mu}m. (laser applications and other topics in quantum electronics)
Meurisse, Guillaume M; Dierick, Frédéric; Schepens, Bénédicte; Bastien, Guillaume J
2016-01-01
In gait lab, the quantification of the ground reaction forces (GRFs) acting upon individual limbs is required for dynamic analysis. However, using a single force plate, only the resultant GRF acting on both limbs is available. The aims of this study are (a) to develop an algorithm allowing a reliable detection of the front foot contact (FC) and the back foot off (FO) time events when walking on a single plate, (b) to reconstruct the vertical GRFs acting upon each limb during the double contact phase (DC) and (c) to evaluate this reconstruction on healthy and clinical gait trials. For the purpose of the study, 811 force measurements during DC were analyzed based on walking trials from 27 healthy subjects and 88 patients. FC and FO are reliably detected using a novel method based on the distance covered by the centre of pressure. The algorithm for the force reconstruction is a revised version of the approach of Davis and Cavanagh [24]. In order to assess the robustness of the algorithm, we compare the resulting GRFs with the real forces measured with individual force plates. The median of the relative error on force reconstruction is 1.8% for the healthy gait and 2.5% for the clinical gait. The reconstructed and the real GRFs during DC are strongly correlated for both healthy and clinical gait data (R(2)=0.998 and 0.991, respectively).
Farina, Simone; Ceretti, Elisabetta; Thepsonti, Thanongsak; Oezel, Tugrul
2011-05-04
Titanium alloys offer superb properties in strength, corrosion resistance and biocompatibility and are commonly utilized in medical devices and implants. Micro-end milling process is a direct and rapid fabrication method for manufacturing medical devices and implants in titanium alloys. Process performance and quality depend upon an understanding of the relationship between cutting parameters and forces and resultant tool deflections to avoid tool breakage. For this purpose, FE simulations of chip formation during micro-end milling of Ti-6Al-4V alloy with an ultra-fine grain solid carbide two-flute micro-end mill are investigated using DEFORM software.At first, specific forces in tangential and radial directions of cutting during micro-end milling for varying feed advance and rotational speeds have been determined using designed FE simulations for chip formation process. Later, these forces are applied to the micro-end mill geometry along the axial depth of cut in 3D analysis of ABAQUS. Consequently, 3D distributions for tool deflections and von Misses stress are determined. These analyses will yield in establishing integrated multi-physics process models for high performance micro-end milling and a leap-forward to process improvements.
NASA Astrophysics Data System (ADS)
Gnutek, Paweł; Açıkgöz, Muhammed; Rudowicz, Czesław
2015-05-01
Superposition model (SPM) analysis of the zero-field splitting parameters (ZFSPs), in short SPM/ZFSP, enables correlation of crystallographic, spectroscopic, and magnetic data for transition ions with an orbitally non-degenerate ground state in crystals. SPM analysis of ZFSPs requires knowledge of the model parameters, i.e. the intrinsic parameters - bbark (R0), power law exponents - tk, and the reference distance - R0. An extensive survey of literature has revealed that the model parameters for Ni2+ (S=1) ions are not available as yet. Hence, in this study we set for determination of the model parameters sets applicable for SPM/ZFSP analysis of Ni2+ ions in the six-fold coordinated NiO6 with axial symmetry. Our method utilizes the relationships between the intrinsic parameters bbark (R0) and the experimental data for the uniaxial-stress parameters obtained for Ni2+ ions in several crystals. The present results enable modeling of the ZFSP b20 = D for Ni2+ (S=1) ions, which hitherto has been hindered by the lack of suitable model parameters sets. Applications of SPM/ZFSP analysis are carried out for Ni2+ ions doped into α-Al2O3 (corundum), α-LiIO3, and LiNbO3, as well as the series of fluosilicate crystals with general formula: ABF6·6R2O (A=Zn, Mg, Co, Ni, Fe; B=Si, Ti, Sn, BF4; R=H, D). These results will be utilized in studies of Ni2+-based systems suitable for pressure sensors in high-pressure electron magnetic resonance (EMR) measurements and spectroscopic properties of Ni2+ ions in Haldane gap systems.
NASA Astrophysics Data System (ADS)
Cheng, Shuying; Doerr, Stefan H.; Bryant, Rob; Wright, Chris J.
2010-05-01
Extraction of soil with solvents is commonly used to isolate fractions of soil organic matter (SOM) thought to cause soil water repellency. Previous studies have assessed the efficiency of extraction procedures by determining sample water repellency and SOM content, before and after extraction, and the ability of extracts to render wettable materials repellent. Here we use atomic force microscopy (AFM) for the direct, high-resolution examination of the effects of the most commonly used solvent (isopropanol/ammonia) on physico-chemical properties of soil particle surfaces. Particles, from three pairs of wettable and water repellent sandy soils, were examined before and after Soxhlet extraction and following extract application to extracted soil material. Complementary evidence was provided by comparison with the effects of exposing clean sand to organic compounds of known composition. The extraction rendered all soils wettable and resulted in a reduction in particle surface area covered by SOM. Subsequent exposure of these wettable particles to extracts (i) re-introduced some level of water repellency despite achieving only a minimal increase in SOM; (ii) led to a more uniform scatter of soft regions, indicative of SOM; but (iii) did not consistently re-create original surface features. The outcomes suggest that (a) although isopropanol/ammonia extraction may be able to isolate key compounds involved in causing water repellency, these compounds appear to be obtained in a form with little affinity for clean mineral surfaces; (b) the extent and distribution of SOM on soil particle surfaces appears to be a critical factor in the expression of water repellency.
ERIC Educational Resources Information Center
Mockovak, William P.
The purpose of this study was to demonstrate a methodology which could be used to estimate the reading skills of Air Force personnel and the reading requirements of different career fields in an attempt to determine the extent of the difference between the reading skills of personnel and the reading requirements of the training materials in a…
Siti Farizwana, M. R.; Mazrura, S.; Zurahanim Fasha, A.; Ahmad Rohi, G.
2010-01-01
The study was to determine the concentration of aluminium (Al) and study the physicochemical parameters (pH, total dissolved solids (TDS), turbidity, and residual chlorine) in drinking water supply in selected palm oil estates in Kota Tinggi, Johor. Water samples were collected from the estates with the private and the public water supplies. The sampling points were at the water source (S), the treatment plant outlet (TPO), and at the nearest houses (H1) and the furthest houses (H2) from the TPO. All estates with private water supply failed to meet the NSDWQ for Al with mean concentration of 0.99 ± 1.52 mg/L. However, Al concentrations in all public water supply estates were well within the limit except for one estate. The pH for all samples complied with the NSDWQ except from the private estates for the drinking water supply with an acidic pH (5.50 ± 0.90). The private water supply showed violated turbidity value in the drinking water samples (14.2 ± 24.1 NTU). Insufficient amount of chlorination was observed in the private water supply estates (0.09 ± 0.30 mg/L). Private water supplies with inefficient water treatment served unsatisfactory drinking water quality to the community which may lead to major health problems. PMID:21461348
Determination of kinetic parameters of Phlomis bovei de Noé using thermogravimetric analysis.
Yahiaoui, Meriem; Hadoun, Hocine; Toumert, Idir; Hassani, Aicha
2015-11-01
This paper reports the pyrolysis study of Phlomis bovei biomass by thermogravimetric experiments in order to determine the thermal degradation behavior and kinetic parameters. The weight losses were found to occur in three stages. In the DTG thermograms, an increase of the heating rate tended to delay thermal degradation processes towards higher temperatures. The average values of activation energy and pre-exponential factor calculated from Ozawa-Flynn-Wall, Kissinger-Akahira-Sunose and Kissinger methods are 134.83, 134.06, 223.31kJ/mol and 4.1610(13), 1.1810(10), 2.8110(11)/s, respectively. The three-pseudo-component method shows that the activation energy increases with increasing the heating rate for hemicellulose and cellulose while the activation energy of the lignin decreased with an increase of the heating rate. Predicted results and experimental data exhibit similar tendencies and the three pseudo-components model with n different from unity 1 is recommended as the most suitable for prediction of kinetic behavior of Phlomis bovei de Noé.
Back-calculation of temperature parameters for determination of asphalt layer modulus
NASA Astrophysics Data System (ADS)
Dong, Qinxi; Matsui, Kunihito; Yamamoto, Kazuya; Higashi, Shigeo
2000-05-01
The pavement elastic modulus of each layer was usually assumed not to be dependent on the environmental factors when the backcalculation of asphalt pavement was conducted from the measured surface deflections of FWD. However, it is well known that the elastic modulus of asphalt layer changes with the variation of temperature. Considering the influence of atmospheric temperature and radiant heat, the temperature distribution is nonlinear along the asphalt layer thickness, and has always been changed. Therefore, the distribution of elastic modulus in the asphalt layer has been considered to change as well. In this paper, we assume the elastic modulus distribution of the asphalt layer to vary with its temperature in terms of the exponential form. Based on the finite element method forward analysis, we propose a method to estimate a standard elastic modulus and temperature coefficient at 20 degrees Celsius for the asphalt layer from the backcalculation analysis. The corresponding FEM backcalculation program using Gauss-Newton method was developed to determine the pavement layer moduli and temperature dependent coefficient, in which the singular value decomposition (SVD) was used for the inverse analysis with scaling of unknown parameters. This method results in a smaller condition number that contributes to improvement of numerical stability. Both numerical simulation and measured data from FWD testing are used to demonstrate the potential applications of this method. As a result, the backcalculation procedure is less dependent on the user's initial values, fast in convergence rate and effective in the pavement engineering.
Jeong, Hyunjo; Zhang, Shuzeng; Li, Xiongbing; Barnard, Dan
2015-09-15
The accurate measurement of acoustic nonlinearity parameter β for fluids or solids generally requires making corrections for diffraction effects due to finite size geometry of transmitter and receiver. These effects are well known in linear acoustics, while those for second harmonic waves have not been well addressed and therefore not properly considered in previous studies. In this work, we explicitly define the attenuation and diffraction corrections using the multi-Gaussian beam (MGB) equations which were developed from the quasilinear solutions of the KZK equation. The effects of making these corrections are examined through the simulation of β determination in water. Diffraction corrections are found to have more significant effects than attenuation corrections, and the β values of water can be estimated experimentally with less than 5% errors when the exact second harmonic diffraction corrections are used together with the negligible attenuation correction effects on the basis of linear frequency dependence between attenuation coefficients, α{sub 2} ≃ 2α{sub 1}.
Rahaman, M S; Ellis, N; Mavinic, D S
2008-01-01
In this paper, struvite (MgNH(4)PO(4).6H(2)O) precipitation kinetics were studied with different operating conditions (varying supersaturation, pH, Mg:P ratio, degree of mixing and seeding conditions) and relevant rate constants were determined by fitting a slightly modified first-order kinetic model to the experimental data obtained. The rate of change of ortho-P concentration in the bulk solutions increases with increasing supersaturation ratio. The estimated rate constants are 2.034, 1.716 and 0.690 hr(-1) for the supersaturation ratio of 9.64, 4.83, and 2.44, respectively. Kinetic parameters were also evaluated for the Mg:P ratio between the ranges of 1.0 and 1.6, indicating higher phosphorus removal efficiency with increasing Mg:P ratio. The rate constants were found to be 0.942, 2.034 and 2.712 hr(-1) for Mg:P ratios of 1.0, 1.3 and 1.6, respectively. The experimental observations for kinetic study of struvite precipitation with different stirrer speeds clearly show that the mixing intensity used had little effect on the intrinsic rate constants. K values found to be 2.034 and 1.902 h(-1) for 100 and 70 rpm, respectively. Seeding, with 250-500 microm of seed crystals during the struvite precipitation kinetics test, was found to have very little effect on the ortho-P removal.
Experimental determination of the bulk Rashba parameters in BiTeBr
NASA Astrophysics Data System (ADS)
Martin, C.; Suslov, A. V.; Buvaev, S.; Hebard, A. F.; Bugnon, P.; Berger, H.; Magrez, A.; Tanner, D. B.
2016-12-01
Shubnikov-de Haas (SdH) oscillations, Hall effect, and optical reflectance (R(ω)) measurements have been performed on single crystals of BiTeBr. Under magnetic fields up to 32 tesla and at temperatures as low as 0.4 K, the SdH data shows a single oscillation frequency F = 102 +/- 5 \\text{tesla} . The combined transport and optical studies establish that the SdH effect originates from the Rashba spin-split bulk conduction band, with the chemical potential situated about 13 meV below the crossing (Dirac) point. The bulk carrier concentration was ne≈5×1018 \\text{cm}-3 and the effective mass m1*= 0.16m0 . Combining SdH and optical data, we reliably determine the Rashba parameters for the bulk conduction band of BiTeBr: the Rashba energy ER = 28 \\text{meV} and the momentum spin-split kR = 0.033 \\unicode{8491}-1 . Hence, the bulk Rashba coupling strength αR = 2ER/kR is found to be 1.7 eVÅ.
The effects of machine parameters on residual stress determined using micro-Raman spectroscopy
Sparks, R.G.; Enloe, W.S.; Paesler, M.A.
1988-12-01
The effects of machine parameters on residual stresses in single point diamond turned silicon and germanium have been investigated using micro-Raman spectroscopy. Residual stresses were sampled across ductile feed cuts in < 100 > silicon and germanium which were single point diamond turned using a variety of feed rates, rake angles and clearance angles. High spatial resolution micro-Raman spectra (1{mu}m spot) were obtained in regions of ductile cutting where no visible surface damage was present. The use of both 514-5nm and 488.0nm excitation wavelengths, by virtue of their differing characteristic penetration depths in the materials, allowed determinations of stress profiles as a function of depth into the sample. Previous discussions have demonstrated that such Raman spectra will exhibit asymmetrically broadened peaks which are characteristic of the superposition of a continuum of Raman scatterers from the various depths probed. Depth profiles of residual stress were obtained using computer deconvolution of the resulting asymmetrically broadened raman spectra.
Siti Farizwana, M R; Mazrura, S; Zurahanim Fasha, A; Ahmad Rohi, G
2010-01-01
The study was to determine the concentration of aluminium (Al) and study the physicochemical parameters (pH, total dissolved solids (TDS), turbidity, and residual chlorine) in drinking water supply in selected palm oil estates in Kota Tinggi, Johor. Water samples were collected from the estates with the private and the public water supplies. The sampling points were at the water source (S), the treatment plant outlet (TPO), and at the nearest houses (H1) and the furthest houses (H2) from the TPO. All estates with private water supply failed to meet the NSDWQ for Al with mean concentration of 0.99 ± 1.52 mg/L. However, Al concentrations in all public water supply estates were well within the limit except for one estate. The pH for all samples complied with the NSDWQ except from the private estates for the drinking water supply with an acidic pH (5.50 ± 0.90). The private water supply showed violated turbidity value in the drinking water samples (14.2 ± 24.1 NTU). Insufficient amount of chlorination was observed in the private water supply estates (0.09 ± 0.30 mg/L). Private water supplies with inefficient water treatment served unsatisfactory drinking water quality to the community which may lead to major health problems.
Pu, Yang; Wang, Wubao; Al-Rubaiee, Mohammad; Gayen, Swapan Kumar; Xu, Min
2012-07-01
Optical extinction and diffuse reflection spectra of cancerous and normal prostate tissues in the 750 to 860 nm spectral range were measured. Optical extinction measurements using thin ex vivo prostate tissue samples were used to determine the scattering coefficient (μ(s)), while diffuse reflection measurements using thick prostate tissue samples were used to extract the absorption coefficient (μ(a)) and the reduced scattering coefficient (μ'(s)). The anisotropy factor (g) was obtained using the extracted values of μ(s) and μ'(s). The values of fractal dimension (D(f)) of cancerous and normal prostate tissues were obtained by fitting to the wavelength dependence of μ'(s). The number of scattering particles contributing to μ(s) as a function of particle size and the cutoff diameter d(max) as a function of g were investigated using the fractal soft tissue model and Mie theory. Results show that d(max) of the normal tissue is larger than that of the cancerous tissue. The cutoff diameter d(max) is observed to agree with the nuclear size for the normal tissues and the nucleolar size for the cancerous tissues. Transmission spectral polarization imaging measurements were performed that could distinguish the cancerous prostate tissue samples from the normal tissue samples based on the differences between their absorption and scattering parameters.
Use of Factorial Analysis to Determine the Interaction Between Parameters of a Land Surface Model
NASA Astrophysics Data System (ADS)
Varejão, C. G.; Varejão, E. V.; Costa, M. H.
2007-05-01
Land surface models use several parameters to represent biophysical processes. These parameters frequently are unknown, reproducing with uncertainty the characteristics of the ecosystem in study. Model calibration techniques find values for each parameter that reduce uncertainty. However, the calibration process is computationally expensive, since is necessary a lot of model runs to have their parameters adjusted. The more parameters are considered, more difficult the process is, particularly when there are interactions among them, and a modification in a parameter value implies in the change of the optimum value of the other parameters. The use of a factorial experiment allows the identification of possible inert parameters, whose values do not influence the final result of the experiment and, therefore, could be excluded from the calibration process. In this work we used factorial analysis to verify the existence of interaction among 5 parameters of the land surface IBIS model - Beta2 (distribution of fine roots), Vmax (maximum Rubisco enzyme capacity), m (coefficient related to the stomatal conductance), CHS (heat capacity of stems) and CHU (heat capacity of leaves) - evaluated against the output fluxes Rn (net radiation), H (sensible heat flux), LE (latent heat flux) and NEE (net ecosystem CO2 exchange). Data was collected at the Amazon tropical rainforest site known as K83, near Santarem, Brazil. The knowledge of the existing interactions between the parameters can considerably reduce the computational cost of further optimization processes, since each parameter that does not interact with others should be optimized independently.
Gu, Zonglin; De Luna, Phil; Yang, Zaixing; Zhou, Ruhong
2017-01-25
Molybdenum disulfide (MoS2) has recently emerged as a promising nanomaterial in a wide range of applications due to its unique and impressive properties. For example, MoS2 has gained attention in the biomedical field because of its ability to act as an antibacterial and anticancer agent. However, the potential influence of this exciting nanomaterial on biomolecules is yet to be extensively studied. Molecular dynamics (MD) simulations are invaluable tools in the examination of protein interactions with nanomaterials such as MoS2. Previous protein MD studies have employed MoS2 force field parameters which were developed to accurately model bulk crystal structures and thermal heat transport but may not necessarily be amendable to its properties at the interface with biomolecules. By adopting a newly developed MoS2 force field, which was designed to better capture its interaction with water and proteins, we have examined the changes in protein structures between the original and refitted MoS2 force field parameters of three representative proteins, polyalanine (α-helix), YAP65 WW-domains (β-sheet), and HP35 (globular protein) when adsorbed onto MoS2 nanomaterials. We find that the original force field, with much larger van der Waals (vdW) contributions, resulted in more dramatic protein structural damage than the refitted parameters. Importantly, some denaturation of the protein tertiary structure and the local secondary structure persisted with the refitted force field albeit overall less severe MoS2 denaturation capacity was found. This work suggests that the denaturation ability of MoS2 to the protein structure is not as dire as previously reported and provides noteworthy findings on the dynamic interactions of proteins with this emergent material.
40 CFR 86.529-98 - Road load force and inertia weight determination.
Code of Federal Regulations, 2012 CFR
2012-07-01
... these limits shall be tested at an equivalent inertial mass and road load force specified by the Administrator. Figure F98-9 follows: Figure F98-9 Loaded vehicle mass (kg) Equivalent inertial mass (kg)...
40 CFR 86.529-98 - Road load force and inertia weight determination.
Code of Federal Regulations, 2014 CFR
2014-07-01
... these limits shall be tested at an equivalent inertial mass and road load force specified by the Administrator. Figure F98-9 follows: Figure F98-9 Loaded vehicle mass (kg) Equivalent inertial mass (kg)...
Determination of the effect of particle thermal conductivity on thermophoretic force
NASA Astrophysics Data System (ADS)
Bosworth, Ryan W.; Ketsdever, Andrew D.
2016-11-01
The contribution of vane thermal conductivity on the Crookes radiometer is experimentally investigated with four vane materials. This work examines increasing the force production of a radiometer vane for applications such as near-space propulsion by increasing the vane's perimeter while decreasing the total surface area of the vane by means of machined holes in the vanes. Experimental results are given for four vane thermal conductivities. These results indicate that force production is improved for vanes with relatively low thermal conductivity.
NASA Technical Reports Server (NTRS)
Knight, J. D.; Xia, Z.; Mccaul, E.; Hacker, H., Jr.
1992-01-01
Calculations of the forces exerted on a journal by a magnetic bearing actuator are presented, along with comparisons to experimentally measured forces. The calculations are based on two-dimensional solutions for the flux distribution in the metal parts and free space, using finite but constant permeability in the metals. Above a relative permeability of 10,000 the effects of changes in permeability are negligible, but below 10,000 decreases in permeability cause significant decreases in the force. The calculated forces are shown to depend on the metal permeability more strongly when the journal is displaced from its centered position. The predicted forces in the principal attractive direction are in good agreement with experiment when a relatively low value of permeability is chosen. The forces measured normal to the axis of symmetry when the journal is displaced from that axis, however, are significantly higher than predicted by theory, even with a value of relative permeability larger than 5000. These results indicate a need for further work including nonlinear permeability distributions.
Chen, Fanxiu; Zhuang, Qi; Zhang, Huixin
2016-06-20
The mechanical behaviors of granular materials are governed by the grain properties and microstructure of the materials. We conducted experiments to study the force transmission in granular materials using plane strain tests. The large amount of nearly continuous displacement data provided by the advanced noncontact experimental technique of digital image correlation (DIC) has provided a means to quantify local displacements and strains at the particle level. The average strain of each particle could be calculated based on the DIC method, and the average stress could be obtained using Hooke's law. The relationship between the stress and particle force could be obtained based on basic Newtonian mechanics and the balance of linear momentum at the particle level. This methodology is introduced and validated. In the testing procedure, the system is tested in real 2D particle cases, and the contact forces and force chain are obtained and analyzed. The system has great potential for analyzing a real granular system and measuring the contact forces and force chain.
Jiang, N. N.; Xing, T.; Wang, P.; Xie, C.; Xu, X. L.
2015-01-01
Effects of water-misting sprays with forced ventilation after transport during summer on meat quality, stress parameters, glycolytic potential and microstructures of muscle in broilers were investigated. A total of 105 mixed-sex Arbor Acres broilers were divided into three treatment groups: i) 45-min transport without rest (T group), ii) 45-min transport with 1-h rest (TR group), iii) 45-min transport with 15-min water-misting sprays with forced ventilation and 45-min rest (TWFR group). The results showed the TWFR group significantly increased (p<0.05) initial muscle pH (pHi) and ultimate pH (pHu) and significantly reduced L* (p<0.05), drip loss, cook loss, creatine kinase, lactate dehydrogenase activity, plasma glucose content, lactate and glycolytic potential when compared with other groups. Microstructure of the muscle from TWFR group broilers under light microscopy showed smaller intercellular spaces among muscle fibers and bundles compared with T group. In conclusion this study indicated water-misting sprays with forced ventilation after transport could relieve the stress caused by transport under high temperature, which was favorable for the broilers’ welfare. Furthermore, water-misting sprays with forced ventilation after transport slowed down the postmortem glycolysis rate and inhibited the occurrence of PSE-like meat in broilers. Although rest after transport could also improve the meat quality, the effect was not as significant as water-misting sprays with forced ventilation after transport. PMID:26580445
Bandura, A V; Sofo, J O; Kubicki, J D
2006-04-27
Plane-wave density functional theory (DFT-PW) calculations were performed on bulk SnO2 (cassiterite) and the (100), (110), (001), and (101) surfaces with and without H2O present. A classical interatomic force field has been developed to describe bulk SnO2 and SnO2-H2O surface interactions. Periodic density functional theory calculations using the program VASP (Kresse et al., 1996) and molecular cluster calculations using Gaussian 03 (Frisch et al., 2003) were used to derive the parametrization of the force field. The program GULP (Gale, 1997) was used to optimize parameters to reproduce experimental and ab initio results. The experimental crystal structure and elastic constants of SnO2 are reproduced reasonably well with the force field. Furthermore, surface atom relaxations and structures of adsorbed H2O molecules agree well between the ab initio and force field predictions. H2O addition above that required to form a monolayer results in consistent structures between the DFT-PW and classical force field results as well.
A feasibility study for experimentally determining dynamic force distribution in a lap joint.
Mayes, Randall Lee
2013-11-01
Developing constitutive models of the physics in mechanical joints is currently stymied by inability to measure forces and displacements within the joint. The current state of the art estimates whole joint stiffness and energy loss per cycle from external measured force input and one or two acceleration responses. To validate constitutive models beyond this state requires a measurement of the distributed forces and displacements at the joint interface. Unfortunately, introducing measurement devices at the interface completely disrupts the desired physics. A feasibility study is presented for a non-intrusive method of solving for the interface dynamic forces from an inverse problem using full field measured responses. The responses come from the viewable surface of a beam. The noise levels associated with digital image correlation and continuous scanning laser Doppler velocimetry are evaluated from typical beam experiments. Two inverse problems are simulated. One utilizes the extended Sum of Weighted Accelerations Technique (SWAT). The second is a new approach dubbed the method of truncated orthogonal forces. These methods are much more robust if the contact patch geometry is well identified. Various approaches to identifying the contact patch are investigated, including ion marker tracking, Prussian blue and ultrasonic measurements. A typical experiment is conceived for a beam which has a lap joint at one end with a single bolt connecting it to another identical beam. In a virtual test using the beam finite element analysis, it appears that the SWAT inverse method requires evaluation of too many coefficients to adequately identify the force distribution to be viable. However, the method of truncated orthogonal forces appears viable with current digital image correlation (and probably other) imaging techniques.
NASA Astrophysics Data System (ADS)
Rao, J. S.; Raghavacharyulu, E.; Seshadri, V.; Rao, V. V. R.
1983-10-01
Determination of non-steady forces in a real turbine stage is difficult due to the local flow conditions, for example high pressures, high temperatures and in-accessibility to the region etc. Experimentation in a real turbine is also prohibitive due to the costs involved. An alternate method of arriving at these non-steady forces through the use of modified hydraulic analogy is discussed. A rotating water table facility, developed and fabricated based on the principles of modified hydraulic analogy is described. A flat plate stage is simulated on the rotating water table, and the results obtained are presented.
Abascal, José L F; Vega, Carlos
2007-06-08
We show that, in order to yield an acceptable phase diagram for water, the key ingredient is the relative strength of the dipolar and quadrupolar forces. We also demonstrate that for three-point-charge water models the relative strength of the dipolar to quadrupolar forces is determined by the position of the negative charge. This provides a theoretical background--supported by the experiment--to our knowledge of the water interactions which at present is essentially dominated by empirical models. In addition, it can be quite useful in the development of improved water models with a more physical basis.
A new methodology for determination of macroscopic transport parameters in drying porous media
NASA Astrophysics Data System (ADS)
Attari Moghaddam, A.; Kharaghani, A.; Tsotsas, E.; Prat, M.
2015-12-01
Two main approaches have been used to model the drying process: The first approach considers the partially saturated porous medium as a continuum and partial differential equations are used to describe the mass, momentum and energy balances of the fluid phases. The continuum-scale models (CM) obtained by this approach involve constitutive laws which require effective material properties, such as the diffusivity, permeability, and thermal conductivity which are often determined by experiments. The second approach considers the material at the pore scale, where the void space is represented by a network of pores (PN). Micro- or nanofluidics models used in each pore give rise to a large system of ordinary differential equations with degrees of freedom at each node of the pore network. In this work, the moisture transport coefficient (D), the pseudo desorption isotherm inside the network and at the evaporative surface are estimated from the post-processing of the three-dimensional pore network drying simulations for fifteen realizations of the pore space geometry from a given probability distribution. A slice sampling method is used in order to extract these parameters from PN simulations. The moisture transport coefficient obtained in this way is shown in Fig. 1a. The minimum of average D values demonstrates the transition between liquid dominated moisture transport region and vapor dominated moisture transport region; a similar behavior has been observed in previous experimental findings. A function is fitted to the average D values and then is fed into the non-linear moisture diffusion equation. The saturation profiles obtained from PN and CM simulations are shown in Fig. 1b. Figure 1: (a) extracted moisture transport coefficient during drying for fifteen realizations of the pore network, (b) average moisture profiles during drying obtained from PN and CM simulations.
Radiographic study of the hip joint to determine anthropometric parameters for Indian population.
Bagaria, Vaibhav; Deshpande, Shirish; Kuthe, Abhay; Rasalkar, Darshana D; Paunipagar, Bhawan K; Madhugiri, Tanushree Subhash
2012-02-01
Hip replacement surgeries are on the rise in India. However, for these surgeries, most of the implants used are imported and manufactured entirely to suit the geometrical considerations of the western population. Studies in the past have shown that there are anatomical variations in the hip joint for different ethnic backgrou