Aliya, F; Begum, H; Reddy, M T; Sivaraj, N; Pandravada, S R; Narshimulu, G
2014-05-01
Fifty genotypes of spine gourd (Momordica dioica Roxb.) were evaluated in a randomized block design with two replications at the Vegetable Research Station, Rajendranagar, Hyderabad, Andhra Pradesh, India during kharif, 2012. Correlation and path coefficient analysis were carried out to study the character association and contribution, respectively for twelve quantitative characters namely vine length (m), number of stems per plant, days to first female flower appearance, first female flowering node, days to first fruit harvest, days to last fruit harvest, fruiting period (days), fruit length (cm), fruit width (cm), fruit weight (g), number of fruits per plant and fruit yield per plant (kg) for identification of the potential selection indices. Correlation and path coefficient analyses revealed that fruiting period and number of fruits per plant not only had positively significant correlation with fruit yield but also had positively high direct effect on it and are regarded as the main determinants of fruit yield. Days to first fruit harvest had positively moderate direct effect on fruit yield and its association was negatively significant, days to last fruit harvest had negatively high direct effect on fruit yield and its association was significant positively, hence restricted simultaneous selection can be made for days to first fruit harvest and days to last fruit harvest. The improvement in fruit yield can be effective if selection is based on days to first fruit harvest, days to last fruit harvest, fruiting period and number of fruits per plant. PMID:26030998
Debebe, Abel; Singh, Harijat; Tefera, Hailu
2014-01-01
This experiment was conducted at Debre Zeit and Akaki during 2004-2005 cropping season on F2-derived F4 bulk families of three crosses, viz, DZ-01-974 x DZ-01-2786, DZ-01-974 x DZ-Cr-37 and Alba x Kaye Murri. To estimate the correlations and path coefficients between yield and yield components, 63 F4 families were taken randomly from each of the three crosses. The 189 F4 families, five parents and two checks were space planted following in 14 x 14 simple lattice design. Study of associations among traits indicated that yield was positively associated with shoot biomass, harvest index, lodging index and panicle kernel weight at phenotypic level at Debre Zeit. At Akaki, yield had significant positive correlation with shoot biomass, harvest index, plant height, panicle length and panicle weight. At genotypic level, grain yield per plot exhibited positive association with harvest index, shoot biomass, lodging index and panicle kernel weight at Debre Zeit. By contrast, days to heading, days to maturity, plant height and panicle length showed negative association with yield. At Akaki, kernel yield per plot was positively correlated at genotypic level with all the traits considered where lodging index had the highest correlation followed by shoot biomass, panicle kernel weight and harvest index. Path coefficient analysis at both phenotypic and genotypic levels for both the locations suggested those shoot biomass and harvest indexes are the two important yield determining traits. These two traits might be useful in indirect selection for yield improvement in the material generated from the three crosses under consideration. PMID:24783784
An Empirical Comparison of Two Path Coefficient Estimates.
ERIC Educational Resources Information Center
Tam, Peter T. K.; And Others
Since the development of causal path analysis by Wright, both the standardized and unstandardized procedures in path coefficient estimates have been advocated in the related literature, but the superiority of one technique over the other has not been demonstrated empirically or mathematically. In this study, the sampling properties of both…
Snell, Mark K.
2007-07-14
The PANL software determines path through an Adversary Sequence Diagram (ASD) with minimum Probability of Interruption, P(I), given the ASD information and data about site detection, delay, and response force times. To accomplish this, the software generates each path through the ASD, then applies the Estimate of Adversary Sequence Interruption (EASI) methodology for calculating P(I) to each path, and keeps track of the path with the lowest P(I). Primary use is for training purposes during courses on physical security design. During such courses PANL will be used to demonstrate to students how more complex software codes are used by the US Department of Energy to determine the most-vulnerable paths and, where security needs improvement, how such codes can help determine physical security upgrades.
2007-07-14
The PANL software determines path through an Adversary Sequence Diagram (ASD) with minimum Probability of Interruption, P(I), given the ASD information and data about site detection, delay, and response force times. To accomplish this, the software generates each path through the ASD, then applies the Estimate of Adversary Sequence Interruption (EASI) methodology for calculating P(I) to each path, and keeps track of the path with the lowest P(I). Primary use is for training purposes duringmore » courses on physical security design. During such courses PANL will be used to demonstrate to students how more complex software codes are used by the US Department of Energy to determine the most-vulnerable paths and, where security needs improvement, how such codes can help determine physical security upgrades.« less
Method of path coefficients: a trademark of Sewall Wright.
Li, C C
1991-02-01
This address is a tribute to a pioneer of population genetics, including human population genetics. The unique methodology employed by Sewall Wright in many genetic problems is the method of path coefficients. This essay traces the historical landmarks in the development of the path method and then shows how some of the conventional statistical results can be converted into expressions involving path coefficients. The construction of a path diagram to represent such statistical results is explained in terms of examples. In the last section an example of applying the path method to the problem of genetic linkage in a random mating population is given. I hope that, despite the ending of the Sewall Wright era, the path method will continue to serve the scientific world. PMID:2004740
Interactive cutting path analysis programs
NASA Technical Reports Server (NTRS)
Weiner, J. M.; Williams, D. S.; Colley, S. R.
1975-01-01
The operation of numerically controlled machine tools is interactively simulated. Four programs were developed to graphically display the cutting paths for a Monarch lathe, Cintimatic mill, Strippit sheet metal punch, and the wiring path for a Standard wire wrap machine. These programs are run on a IMLAC PDS-ID graphic display system under the DOS-3 disk operating system. The cutting path analysis programs accept input via both paper tape and disk file.
Maity, S; Gorai, A K; Pal, A K
2006-06-01
This paper elucidates the basic approach of determining the path coefficients and its significance in the road traffic noise annoyance. Path model not only outline the direct effect of the traffic noise on the nearby residents but also indicate the indirect effect via other variables. In this study seven variables were considered for determining road traffic noise annoyance. However the same would be equally applicable for other situations like aircraft noise, rail noise, and industry noise with the different variables. At the outset a priori path model was designed and then on the basis of the partial regression coefficient values for the different paths, the revised path model was developed. The standardized partial regression coefficients known as path coefficients, determine the strength of the linkage among variables. Some of the paths in the model were not statistically significant. Revised path models were developed by deleting the insignificant paths whose values were found above 5% level. In the revised path model, thus the direct and indirect effect due to a particular variable causing the road traffic noise annoyance could be observed. PMID:16917695
Analysis of internal conversion coefficients
Coursol; Gorozhankin; Yakushev; Briancon; Vylov
2000-03-01
An extensive database has been assembled that contains the three most widely used sets of calculated internal conversion coefficients (ICC): [Hager R.S., Seltzer E.C., 1968. Internal conversion tables. K-, L-, M-shell Conversion coefficients for Z = 30 to Z = 103, Nucl. Data Tables A4, 1-237; Band I.M., Trzhaskovskaya M.B., 1978. Tables of gamma-ray internal conversion coefficients for the K-, L- and M-shells, 10 < or = Z < or = 104, Special Report of Leningrad Nuclear Physics Institute; Rosel F., Fries H.M., Alder K., Pauli H.C., 1978. Internal conversion coefficients for all atomic shells, At. Data Nucl. Data Tables 21, 91-289] and also includes new Dirac Fock calculations [Band I.M. and Trzhaskovskaya M.B., 1993. Internal conversion coefficients for low-energy nuclear transitions, At. Data Nucl. Data Tables 55, 43-61]. This database is linked to a computer program to plot ICCs and their combinations (sums and ratios) as a function of Z and energy, as well as relative deviations of ICC or their combinations for any pair of tabulated data. Examples of these analyses are presented for the K-shell and total ICCs of the gamma-ray standards [Hansen H.H., 1985. Evaluation of K-shell and total internal conversion coefficients for some selected nuclear transitions, Eur. Appl. Res. Rept. Nucl. Sci. Tech. 11.6 (4) 777-816] and for the K-shell and total ICCs of high multipolarity transitions (total, K-, L-, M-shells of E3 and M3 and K-shell of M4). Experimental data sets are also compared with the theoretical values of these specific calculations. PMID:10724406
Fidan, Barış; Umay, Ilknur
2015-01-01
Accurate signal-source and signal-reflector target localization tasks via mobile sensory units and wireless sensor networks (WSNs), including those for environmental monitoring via sensory UAVs, require precise knowledge of specific signal propagation properties of the environment, which are permittivity and path loss coefficients for the electromagnetic signal case. Thus, accurate estimation of these coefficients has significant importance for the accuracy of location estimates. In this paper, we propose a geometric cooperative technique to instantaneously estimate such coefficients, with details provided for received signal strength (RSS) and time-of-flight (TOF)-based range sensors. The proposed technique is integrated to a recursive least squares (RLS)-based adaptive localization scheme and an adaptive motion control law, to construct adaptive target localization and adaptive target tracking algorithms, respectively, that are robust to uncertainties in aforementioned environmental signal propagation coefficients. The efficiency of the proposed adaptive localization and tracking techniques are both mathematically analysed and verified via simulation experiments. PMID:26690441
Fidan, Barış; Umay, Ilknur
2015-01-01
Accurate signal-source and signal-reflector target localization tasks via mobile sensory units and wireless sensor networks (WSNs), including those for environmental monitoring via sensory UAVs, require precise knowledge of specific signal propagation properties of the environment, which are permittivity and path loss coefficients for the electromagnetic signal case. Thus, accurate estimation of these coefficients has significant importance for the accuracy of location estimates. In this paper, we propose a geometric cooperative technique to instantaneously estimate such coefficients, with details provided for received signal strength (RSS) and time-of-flight (TOF)-based range sensors. The proposed technique is integrated to a recursive least squares (RLS)-based adaptive localization scheme and an adaptive motion control law, to construct adaptive target localization and adaptive target tracking algorithms, respectively, that are robust to uncertainties in aforementioned environmental signal propagation coefficients. The efficiency of the proposed adaptive localization and tracking techniques are both mathematically analysed and verified via simulation experiments. PMID:26690441
Path-integral calculation of the third virial coefficient of quantum gases at low temperatures
Garberoglio, Giovanni; Harvey, Allan H.
2011-04-07
We derive path-integral expressions for the second and third virial coefficients of monatomic quantum gases. Unlike previous work that considered only Boltzmann statistics, we include exchange effects (Bose-Einstein or Fermi-Dirac statistics). We use state-of-the-art pair and three-body potentials to calculate the third virial coefficient of {sup 3}He and {sup 4}He in the temperature range 2.6-24.5561 K. We obtain uncertainties smaller than those of the limited experimental data. Inclusion of exchange effects is necessary to obtain accurate results below about 7 K.
Differential fertility in Bangladesh: a path analysis.
Ahmed, B
1981-01-01
Previous studies of fertility in Bangladesh have mostly used crosstabular and multivariate analyses revealing the direct effect of selected socioeconomic and background variables. The indirect effects are relatively unknown. Analysis of data from the 1975-1976 Bangladesh Fertility Survey seeks to identify variables that significantly affect the cumulative fertility of both urban and rural women and to construct causal models to clarify the complex set of relationships. Path analysis is used on 8 variables: fertility index (number of children ever born to ever married women aged 9-49, age of wife (respondent), age at marriage, religion, childhood background of wife and husband, and educational attainment of both wife and husband. Data obtained from a sample of 4875 rural and 1403 urban women are used. Causal ordering of the variables began with the 4 exogenous variables: age, religion, and childhood backgrounds of the wife and husband. Education of husband and wife are placed next in sequence, followed by age at marriage and the fertility index. Path coefficients are estimated by applying ordinary least squares regression to the equations. "Children ever born" is regressed on all other variables for urban and rural areas. The 2 sets of coefficients are not equivalent and urban and rural data are analyzed separately. 13 paths are significant in the urban model and 11 in the rural model. The coefficients are small suggesting that other variables not included in the study effect fertility. In the urban model, 5 variables were found to have a statistically significant effect on fertility: age, religion, education for both husband and wife, and age at marriage. The indirect effect of religion operating through a network of compound paths suggests that Muslim affiliation tends to depress wife's and husband's education and age at marriage. Holding other variables constant, Muslim women tend to have more children than non-Muslim women. Wife's age at marriage negatively
Garberoglio, Giovanni; Jankowski, Piotr; Szalewicz, Krzysztof; Harvey, Allan H.
2014-07-28
We present a path-integral Monte Carlo procedure for the fully quantum calculation of the second molecular virial coefficient accounting for intramolecular flexibility. This method is applied to molecular hydrogen (H{sub 2}) and deuterium (D{sub 2}) in the temperature range 15–2000 K, showing that the effect of molecular flexibility is not negligible. Our results are in good agreement with experimental data, as well as with virials given by recent empirical equations of state, although some discrepancies are observed for H{sub 2} between 100 and 200 K.
Soccer ball lift coefficients via trajectory analysis
NASA Astrophysics Data System (ADS)
Goff, John Eric; Carré, Matt J.
2010-07-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin parameters that have not been obtained by today's wind tunnels. Our trajectory analysis technique is not only a valuable tool for professional sports scientists, it is also accessible to students with a background in undergraduate-level classical mechanics.
ERIC Educational Resources Information Center
Tsai, Tien-Lung; Shau, Wen-Yi; Hu, Fu-Chang
2006-01-01
This article generalizes linear path analysis (PA) and simultaneous equations models (SiEM) to deal with mixed responses of different types in a recursive or triangular system. An efficient instrumental variable (IV) method for estimating the structural coefficients of a 2-equation partially recursive generalized path analysis (GPA) model and…
Path analysis in genetic epidemiology: a critique.
Karlin, S; Cameron, E C; Chakraborty, R
1983-01-01
Path analysis, a form of general linear structural equation models, is used in studies of human genetics data to discern genetic, environmental, and cultural factors contributing to familial resemblance. It postulates a set of linear and additive parametric relationships between phenotypes and genetic and cultural variables and then essentially uses the assumption of multivariate normality to estimate and perform tests of hypothesis on parameters. Such an approach has been advocated for the analysis of genetic epidemiological data by D. C. Rao, N. Morton, C. R. Cloninger, L. J. Eaves, and W. E. Nance, among others. This paper reviews and evaluates the formulations, assumptions, methodological procedures, interpretations, and applications of path analysis. To give perspective, we begin with a discussion of path analysis as it occurs in the form of general linear causal models in several disciplines of the social sciences. Several specific path analysis models applied to lipoprotein concentrations, IQ, and twin data are then reviewed to keep the presentation self-contained. The bulk of the critical discussion that follows is directed toward the following four facets of path analysis: (1) coherence of model specification and applicability to data; (2) plausibility of modeling assumptions; (3) interpretability and utility of the model; and (4) validity of statistical and computational procedures. In the concluding section, a brief discussion of the problem of appropriate model selection is presented, followed by a number of suggestions of essentially model-free alternative methods of use in the treatment of complex structured data such as occurs in genetic epidemiology. PMID:6349335
A taxonomy of integral reaction path analysis
Grcar, Joseph F.; Day, Marcus S.; Bell, John B.
2004-12-23
W. C. Gardiner observed that achieving understanding through combustion modeling is limited by the ability to recognize the implications of what has been computed and to draw conclusions about the elementary steps underlying the reaction mechanism. This difficulty can be overcome in part by making better use of reaction path analysis in the context of multidimensional flame simulations. Following a survey of current practice, an integral reaction flux is formulated in terms of conserved scalars that can be calculated in a fully automated way. Conditional analyses are then introduced, and a taxonomy for bidirectional path analysis is explored. Many examples illustrate the resulting path analysis and uncover some new results about nonpremixed methane-air laminar jets.
A Critical Path Analysis of Scientific Productivity.
ERIC Educational Resources Information Center
Loehle, Craig
1994-01-01
This article presents a queuing model simulation of scientific productivity utilizing critical path analysis. Creativity is found to have a large positive effect, a negative effect, or no effect on productivity, depending on the stage of the problem-solving process to which it is applied and the nature of the bottlenecks inherent to the specific…
Behavioral Path Analysis and Environmental Evaluation.
ERIC Educational Resources Information Center
Wise, James A.; Kahle, Ellen
Behavioral Path Analysis is both a theory and a methodology for studying person-environment interactions. It is designed to be applicable to the evaluation of both environments in use and proposed designed environments. This paper presents the basics of the theory, and some examples of recent applications that have guided its development. The…
Path Analysis: A Link between Family Theory and Reseach.
ERIC Educational Resources Information Center
Rank, Mark R.; Sabatelli, Ronald M.
This paper discusses path analysis and the applicability of this methodology to the field of family studies. The statistical assumptions made in path analysis are presented along with a description of the two types of models within path analysis, i.e., recursive and non-recursive. Methods of calculating in the path model and the advantages of…
Adaptive path planning: Algorithm and analysis
Chen, Pang C.
1995-03-01
To address the need for a fast path planner, we present a learning algorithm that improves path planning by using past experience to enhance future performance. The algorithm relies on an existing path planner to provide solutions difficult tasks. From these solutions, an evolving sparse work of useful robot configurations is learned to support faster planning. More generally, the algorithm provides a framework in which a slow but effective planner may be improved both cost-wise and capability-wise by a faster but less effective planner coupled with experience. We analyze algorithm by formalizing the concept of improvability and deriving conditions under which a planner can be improved within the framework. The analysis is based on two stochastic models, one pessimistic (on task complexity), the other randomized (on experience utility). Using these models, we derive quantitative bounds to predict the learning behavior. We use these estimation tools to characterize the situations in which the algorithm is useful and to provide bounds on the training time. In particular, we show how to predict the maximum achievable speedup. Additionally, our analysis techniques are elementary and should be useful for studying other types of probabilistic learning as well.
Soccer Ball Lift Coefficients via Trajectory Analysis
ERIC Educational Resources Information Center
Goff, John Eric; Carre, Matt J.
2010-01-01
We performed experiments in which a soccer ball was launched from a machine while two high-speed cameras recorded portions of the trajectory. Using the trajectory data and published drag coefficients, we extracted lift coefficients for a soccer ball. We determined lift coefficients for a wide range of spin parameters, including several spin…
Statechart Analysis with Symbolic PathFinder
NASA Technical Reports Server (NTRS)
Pasareanu, Corina S.
2012-01-01
We report here on our on-going work that addresses the automated analysis and test case generation for software systems modeled using multiple Statechart formalisms. The work is motivated by large programs such as NASA Exploration, that involve multiple systems that interact via safety-critical protocols and are designed with different Statechart variants. To verify these safety-critical systems, we have developed Polyglot, a framework for modeling and analysis of model-based software written using different Statechart formalisms. Polyglot uses a common intermediate representation with customizable Statechart semantics and leverages the analysis and test generation capabilities of the Symbolic PathFinder tool. Polyglot is used as follows: First, the structure of the Statechart model (expressed in Matlab Stateflow or Rational Rhapsody) is translated into a common intermediate representation (IR). The IR is then translated into Java code that represents the structure of the model. The semantics are provided as "pluggable" modules.
Performance Analysis of Path Planning Modeling
NASA Astrophysics Data System (ADS)
Wang, Zhirui; Li, Shuanghong; Zhang, Ying; Du, Qiaoling
Ant colony system (ACS) algorithm was applied to the path planning for the robot. In the same working environment, path planning based on MAKLINK graph theory and Voronoi diagram were simulated and compared. MAKLINK graph theory is appropriate to apply to precise searching in small-scale district, and Voronoi diagram is suitable for fast path planning in a large area.
Adaptive path planning: Algorithm and analysis
Chen, Pang C.
1993-03-01
Path planning has to be fast to support real-time robot programming. Unfortunately, current planning techniques are still too slow to be effective, as they often require several minutes, if not hours of computation. To alleviate this problem, we present a learning algorithm that uses past experience to enhance future performance. The algorithm relies on an existing path planner to provide solutions to difficult tasks. From these solutions, an evolving sparse network of useful subgoals is learned to support faster planning. The algorithm is suitable for both stationary and incrementally-changing environments. To analyze our algorithm, we use a previously developed stochastic model that quantifies experience utility. Using this model, we characterize the situations in which the adaptive planner is useful, and provide quantitative bounds to predict its behavior. The results are demonstrated with problems in manipulator planning. Our algorithm and analysis are sufficiently general that they may also be applied to task planning or other planning domains in which experience is useful.
NASA Technical Reports Server (NTRS)
Rinsland, Curtis P.; Smith, Mary Ann H.; Goldman, Aaron; Malathy Devi, V.
1991-01-01
Lorentz air-broadening coefficients and relative intensities have been measured for forty-three lines in the pure rotational band and twenty lines in the nu2 band of H2O-16 between 800 and 1150/cm. The results were derived from analysis of nine 0.017/cm-resolution atmospheric absorption spectra recorded over horizontal paths of 0.5-1.5 km with the McMath Fourier transform spectrometer and main solar telescope operated on Kitt Peak by the National Solar Observatory. A nonlinear least-squares spectral fitting technique was used in the spectral analysis. The results are compared with previous measurements and calculations. In most cases, the measured pressure-broadening coefficients and intensities are significantly different from the values in the 1986 HITRAN line parameters compilation.
NASA Technical Reports Server (NTRS)
Palazzolo, Alan; Bhattacharya, Avijit; Athavale, Mahesh; Venkataraman, Balaji; Ryan, Steve; Funston, Kerry
1997-01-01
This paper highlights bulk flow and CFD-based models prepared to calculate force and leakage properties for seals and shrouded impeller leakage paths. The bulk flow approach uses a Hir's based friction model and the CFD approach solves the Navier Stoke's (NS) equation with a finite whirl orbit or via analytical perturbation. The results show good agreement in most instances with available benchmarks.
A new coefficient of concordance with applications to biosignal analysis
NASA Astrophysics Data System (ADS)
Xu, Weichao; Chen, Zhaoguo; Liu, Wenqing
2015-12-01
In this paper we propose a novel concordance coefficients called Order Statistics Concordance Coefficients based on order statistics and Pearson's Product Moment Correlation Coefficient. For comparison, we also construct other three similar index based on Average Pearson's Product Moment Correlation Coefficient, Kendall's Concordance Coefficients, Average Kendall's tau. We propose Multivariate Normal Model to estimate the correlation coefficient, Linear Model and Nonlinear Model to model the linear and nonlinear association between multichannel signals, And we also apply the concordance coefficients to biosignal analysis developed a new organizational index for quantifying organization of AF. Statistical evidences suggest that (a) Order Statistics Concordance Coefficients have better robust than other three index; (b) capable of distinguishing fibrillatory rhythms from nonfibrillatory rhythms, such as Atiral flutter; (c) can reflect the effectiveness of adenosine, a drug commonly used during electrophysiological procedures; and (d) perform better than other three concordance coefficients.
Improved analysis of impurity transport coefficient profiles
NASA Astrophysics Data System (ADS)
Chilenski, M. A.; Greenwald, M.; Marzouk, Y.; Howard, N. T.; Rice, J.; White, A. E.
2015-11-01
Work is underway on the development of a novel technique to estimate impurity transport coefficient profiles and their uncertainties. Inference of impurity transport coefficient profiles using x-ray imaging crystal spectroscopy measurements of laser blow-off impurity injections has played a key role in the validation of gyrokinetic simulations of impurity transport in L-mode (Howard et al. 2012, Nucl. Fusion 52, 063002). Recent attempts to apply the existing methodology for interpreting such measurements to H-mode have failed to yield reliable estimates, however. This failure exposes key issues regarding the uniqueness of the solution and the rigorous estimation of the uncertainty. A new approach is under development which uses a combination of Markov chain Monte Carlo (MCMC) and global optimization techniques to estimate impurity transport coefficient profiles even when there are multiple possible solutions. This poster will present the new methodology in detail and will show preliminary results from applying it to Alcator C-Mod data. This new approach will enable us to test the existing understanding of L-mode impurity transport and to move towards multichannel validation of gyrokinetic simulations of H-modes. Supported by USDOE award DE-FC02-99ER54512.
Generalized skew coefficients for flood-frequency analysis in Minnesota
Lorenz, D.L.
1997-01-01
This report presents an evaluation of generalized skew coefficients used in flood-frequency analysis. Station skew coefficients were computed for 267 long-term stream-gaging stations in Minnesota and the surrounding states of Iowa, North and South Dakota, Wisconsin, and the provinces of Manitoba and Ontario, Canada. Generalized skew coefficients were computed from station skew coefficients using a locally weighted regression technique. The resulting regression trend surface was the generalized skew coefficient map, except for the North Shore area, and has a mean square error of 0.182.
Tikhonov regularization-based operational transfer path analysis
NASA Astrophysics Data System (ADS)
Cheng, Wei; Lu, Yingying; Zhang, Zhousuo
2016-06-01
To overcome ill-posed problems in operational transfer path analysis (OTPA), and improve the stability of solutions, this paper proposes a novel OTPA based on Tikhonov regularization, which considers both fitting degrees and stability of solutions. Firstly, fundamental theory of Tikhonov regularization-based OTPA is presented, and comparative studies are provided to validate the effectiveness on ill-posed problems. Secondly, transfer path analysis and source contribution evaluations for numerical cases studies on spherical radiating acoustical sources are comparatively studied. Finally, transfer path analysis and source contribution evaluations for experimental case studies on a test bed with thin shell structures are provided. This study provides more accurate transfer path analysis for mechanical systems, which can benefit for vibration reduction by structural path optimization. Furthermore, with accurate evaluation of source contributions, vibration monitoring and control by active controlling vibration sources can be effectively carried out.
Structure coefficients for use in stellar analysis
NASA Astrophysics Data System (ADS)
İnlek, Gülay; Budding, Edwin
2012-12-01
We present new values of the structural coefficients η j , and related quantities, for realistic models of distorted stars in close binary systems. Our procedure involves numerical integration of Radau's equation for detailed structural data and we verified our technique by referring to the 8-digit results of Brooker & Olle (Mon. Not. R. Astron. Soc. 115:101, 1955) for purely mathematical models. We provide tables of representative values of η j , and related quantities, for j=2,3,…,7 for a selection of Zero Age Stellar Main Sequence (ZAMS) stellar models taken from the EZWeb compilation of the Dept. of Astronomy, University of Wisconsin-Madison. We include also some preliminary comparisons of our findings with the results of Claret and Gimenez (Astron. Astrophys. 519:A57 2010) for some observed stars.
Folded-path optical analysis gas cell
Carangelo, R.M.; Wright, D.D.
1995-08-08
A folded-path gas cell employs an elliptical concave mirror in confronting relationship to two substantially spherical concave mirrors. At least one of the spherical mirrors, and usually both, are formed with an added cylindrical component to increase orthogonal foci coincidence and thereby to increase the radiation energy throughput characteristic of the cell. 10 figs.
Folded-path optical analysis gas cell
Carangelo, Robert M.; Wright, David D.
1995-01-01
A folded-path gas cell employs an elliptical concave mirror in confronting relationship to two substantially spherical concave mirrors. At least one of the spherical mirrors, and usually both, are formed with an added cylindrical component to increase orthogonal focii coincidence and thereby to increase the radiation energy throughput characteristic of the cell.
Guenole, Nigel; Brown, Anna
2014-01-01
We report a Monte Carlo study examining the effects of two strategies for handling measurement non-invariance – modeling and ignoring non-invariant items – on structural regression coefficients between latent variables measured with item response theory models for categorical indicators. These strategies were examined across four levels and three types of non-invariance – non-invariant loadings, non-invariant thresholds, and combined non-invariance on loadings and thresholds – in simple, partial, mediated and moderated regression models where the non-invariant latent variable occupied predictor, mediator, and criterion positions in the structural regression models. When non-invariance is ignored in the latent predictor, the focal group regression parameters are biased in the opposite direction to the difference in loadings and thresholds relative to the referent group (i.e., lower loadings and thresholds for the focal group lead to overestimated regression parameters). With criterion non-invariance, the focal group regression parameters are biased in the same direction as the difference in loadings and thresholds relative to the referent group. While unacceptable levels of parameter bias were confined to the focal group, bias occurred at considerably lower levels of ignored non-invariance than was previously recognized in referent and focal groups. PMID:25278911
Analysis of a heat transfer device for measuring film coefficients
NASA Technical Reports Server (NTRS)
Medrow, R. A.; Johnson, R. L.; Loomis, W. R.; Wedeven, L. D.
1975-01-01
A heat transfer device consisting of a heated rotating cylinder in a bath was analyzed for its effectiveness to determine heat transfer coefficient of fluids. A time dependent analysis shows that the performance is insensitive to the value of heat transfer coefficient with the given rig configuration.
Assessment of weighted-least-squares-based gas path analysis
NASA Astrophysics Data System (ADS)
Doel, D. L.
1994-04-01
Manufacturers of gas turbines have searched for three decades for a reliable way to use gas path measurements to determine the health of jet engine components. They have been hindered in this pursuit by the quality of the measurements used to carry out the analysis. Engine manufacturers have chosen weighted-least-squares techniques to reduce the inaccuracy caused by sensor error. While these algorithms are clearly an improvement over the previous generation of gas path analysis programs, they still fail in many situations. This paper describes some of the failures and explores their relationship to the underlying analysis technique. It also describes difficulties in implementing a gas path analysis program. The paper concludes with an appraisal of weighted-least-squares-based gas path analysis.
Vibration Analysis of a Split Path Gearbox
NASA Technical Reports Server (NTRS)
Krantz, Timothy L.; Rashidi, Majid
1995-01-01
Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.
NASA Astrophysics Data System (ADS)
Dave, Prashant; Bhushan, Mani; Venkataraman, Chandra
2016-04-01
Aerosols can modulate variability of Indian summer monsoon by perturbing the radiative balance of the atmosphere, affecting the land-ocean processes and altering the cloud-microphysics at varying spatio-temporal scale, ranging from fast (less than a day) to slow (months) temporal effects. In the literature, overall interaction between AOD and Precipitation was quantified as correlation coefficients (Ramchandran and Kedia, 2013; Gryspeerdt et al., 2012; Gryspeerdt et al., 2014), however the segregation of the interaction was required to better understand the presence/absence of pathway mediated through changes in cloud-microphysics and atmospheric stability. In this work, effects of aerosols on precipitation, mediated through changes in cloud-microphysics and atmospheric stability, on daily time-scales, are studied and quantified using coincident observational data of aerosols, clouds and rainfall, using Path-analysis (Wright, 1969). MODIS, ERA-interim and IMD data-sets for years 2000-2009 for Aerosol optical depth (AOD), Column water vapour (CWV), Cloud droplet effective radius (CDERL), Convective available potential energy (CAPE) and Precipitation, over Indian region were used for the analysis. Cause-effect model was built to validate and quantify the effects of AOD on precipitation, mediated through CDERL and CAPE. To contrast cause-effect mechanism in presence and absence of aerosol fields, high AOD-low Precipitation and low AOD-low Precipitation clusters were formed. Cluster-averaged time series were used to calculate the lagged correlation (AOD leading) and provided as input to Path-analysis. "AOD-CDERL-Precipitation" and "AOD-CAPE-Precipitation" pathways were found to be statistically significant for high AOD-low Precipitation clusters while both were absent for low AOD-low Precipitation clusters, for years 2003 and 2004. For other years statistically significant pathway between AOD and Precipitation could not be found. In "AOD-CDERL-Precipitation" pathway
[Electroencephalogram Feature Selection Based on Correlation Coefficient Analysis].
Zhou, Jinzhi; Tang, Xiaofang
2015-08-01
In order to improve the accuracy of classification with small amount of motor imagery training data on the development of brain-computer interface (BCD systems, we proposed an analyzing method to automatically select the characteristic parameters based on correlation coefficient analysis. Throughout the five sample data of dataset IV a from 2005 BCI Competition, we utilized short-time Fourier transform (STFT) and correlation coefficient calculation to reduce the number of primitive electroencephalogram dimension, then introduced feature extraction based on common spatial pattern (CSP) and classified by linear discriminant analysis (LDA). Simulation results showed that the average rate of classification accuracy could be improved by using correlation coefficient feature selection method than those without using this algorithm. Comparing with support vector machine (SVM) optimization features algorithm, the correlation coefficient analysis can lead better selection parameters to improve the accuracy of classification. PMID:26710441
Seismic refraction analysis: the path forward
Haines, Seth S.; Zelt, Colin; Doll, William
2012-01-01
Seismic Refraction Methods: Unleashing the Potential and Understanding the Limitations; Tucson, Arizona, 29 March 2012 A workshop focused on seismic refraction methods took place on 29 May 2012, associated with the 2012 Symposium on the Application of Geophysics to Engineering and Environmental Problems. This workshop was convened to assess the current state of the science and discuss paths forward, with a primary focus on near-surface problems but with an eye on all applications. The agenda included talks on these topics from a number of experts interspersed with discussion and a dedicated discussion period to finish the day. Discussion proved lively at times, and workshop participants delved into many topics central to seismic refraction work.
PathVisio 3: An Extendable Pathway Analysis Toolbox
Kutmon, Martina; van Iersel, Martijn P.; Bohler, Anwesha; Kelder, Thomas; Nunes, Nuno; Pico, Alexander R.; Evelo, Chris T.
2015-01-01
PathVisio is a commonly used pathway editor, visualization and analysis software. Biological pathways have been used by biologists for many years to describe the detailed steps in biological processes. Those powerful, visual representations help researchers to better understand, share and discuss knowledge. Since the first publication of PathVisio in 2008, the original paper was cited more than 170 times and PathVisio was used in many different biological studies. As an online editor PathVisio is also integrated in the community curated pathway database WikiPathways. Here we present the third version of PathVisio with the newest additions and improvements of the application. The core features of PathVisio are pathway drawing, advanced data visualization and pathway statistics. Additionally, PathVisio 3 introduces a new powerful extension systems that allows other developers to contribute additional functionality in form of plugins without changing the core application. PathVisio can be downloaded from http://www.pathvisio.org and in 2014 PathVisio 3 has been downloaded over 5,500 times. There are already more than 15 plugins available in the central plugin repository. PathVisio is a freely available, open-source tool published under the Apache 2.0 license (http://www.apache.org/licenses/LICENSE-2.0). It is implemented in Java and thus runs on all major operating systems. The code repository is available at http://svn.bigcat.unimaas.nl/pathvisio. The support mailing list for users is available on https://groups.google.com/forum/#!forum/wikipathways-discuss and for developers on https://groups.google.com/forum/#!forum/wikipathways-devel. PMID:25706687
Path analysis: A model for the development of scientific reasoning abilities in adolescents
NASA Astrophysics Data System (ADS)
Stuessy, Carol L.
A model was formulated and tested for the development of scientific reasoning abilities in adolescents. Piagetian theory provided the framework for choosing potential determinants of the dependent variable, scientific reasoning abilities. A model reflecting hypothesized causal relationships among determinants and with the dependent variable was developed a priori on the basis of theoretical and substantive reasoning. The hypothesized model was tested and revised using path analysis. Data from intact classes of middle-school (n = 101) and high-school (n = 89) students from an upper-middle-class suburb of a midwestern city revealed significant (p < 0.05) path coefficients for these variables and scientific reasoning abilities: age, I.Q., field dependence-independence, and experience. A path from locus of control to scientific reasoning abilities through field dependence-independence was also statistically significant. The revised model explained 61 percent of the variance in scientific reasoning abilities.
Path Analysis: An Introduction and Analysis of a Decade of Research.
ERIC Educational Resources Information Center
Stage, Frances K.; Carter, Hasani C.; Nora, Amaury
2004-01-01
The authors review the use and interpretations of path analyses in articles published in The Journal of Educational Research from 1992 to 2002 and discuss related issues. This article provides (a) a brief introduction to path analysis, (b) suggested guidelines and recommendations for reporting results, (c) a sample of a model path analysis, (d)…
Path Similarity Analysis: A Method for Quantifying Macromolecular Pathways
Seyler, Sean L.; Kumar, Avishek; Thorpe, M. F.; Beckstein, Oliver
2015-01-01
Diverse classes of proteins function through large-scale conformational changes and various sophisticated computational algorithms have been proposed to enhance sampling of these macromolecular transition paths. Because such paths are curves in a high-dimensional space, it has been difficult to quantitatively compare multiple paths, a necessary prerequisite to, for instance, assess the quality of different algorithms. We introduce a method named Path Similarity Analysis (PSA) that enables us to quantify the similarity between two arbitrary paths and extract the atomic-scale determinants responsible for their differences. PSA utilizes the full information available in 3N-dimensional configuration space trajectories by employing the Hausdorff or Fréchet metrics (adopted from computational geometry) to quantify the degree of similarity between piecewise-linear curves. It thus completely avoids relying on projections into low dimensional spaces, as used in traditional approaches. To elucidate the principles of PSA, we quantified the effect of path roughness induced by thermal fluctuations using a toy model system. Using, as an example, the closed-to-open transitions of the enzyme adenylate kinase (AdK) in its substrate-free form, we compared a range of protein transition path-generating algorithms. Molecular dynamics-based dynamic importance sampling (DIMS) MD and targeted MD (TMD) and the purely geometric FRODA (Framework Rigidity Optimized Dynamics Algorithm) were tested along with seven other methods publicly available on servers, including several based on the popular elastic network model (ENM). PSA with clustering revealed that paths produced by a given method are more similar to each other than to those from another method and, for instance, that the ENM-based methods produced relatively similar paths. PSA applied to ensembles of DIMS MD and FRODA trajectories of the conformational transition of diphtheria toxin, a particularly challenging example, showed that
A Path-Analysis Model of Secondary Physics Enrollments
ERIC Educational Resources Information Center
Bryant, Lee T.; Doran, Rodney L.
1977-01-01
Develops a path-analysis model of critical variables affecting student enrollment in secondary school physics. A test of the model utilizing state provided data of physics enrollment in New York State resulted in the rejection of the model; however, significant critical variable results were obtained. (SL)
Start and Stop Rules for Exploratory Path Analysis.
ERIC Educational Resources Information Center
Shipley, Bill
2002-01-01
Describes a method for choosing rejection probabilities for the tests of independence that are used in constraint-based algorithms of exploratory path analysis. The method consists of generating a Markov or semi-Markov model from the equivalence class represented by a partial ancestral graph and then testing the d-separation implications. (SLD)
Quantifying tight-gas sandstone permeability via critical path analysis
Technology Transfer Automated Retrieval System (TEKTRAN)
Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, especially in spatially complex rocks. In this letter, we apply critical path analysis (CPA) to estimate perm...
Establishing a Causal Model for Bloom's Taxonomy through Path Analysis.
ERIC Educational Resources Information Center
O'Hara, Takeshi; And Others
Path analysis was used to reanalyze Kropp and Stoker's data from tests designed to evaluate Bloom's taxonomy of educational objectives in the cognitive domain. Scores for 1,128 students in grades nine through twelve were analyzed separately by grade level for four content areas on six taxonomic levels. A measure of general ability was also…
Ultraviolet scattering propagation modeling: analysis of path loss versus range.
Drost, Robert J; Moore, Terrence J; Sadler, Brian M
2013-11-01
Modeling of the complex atmospheric propagation of deep-ultraviolet (UV) radiation is important for applications such as non-line-of-sight (NLOS) UV communications. Building upon prior work in which it was observed that short-range, singly scattered NLOS path loss varies linearly with range, we formalize this relationship, generalizing it to consider any order of scattering and more-general system characteristics. In particular, we derive the approximate relationship PL[proportionality]r(2-n) between path loss PL and range r for nth-order scattered radiation, and investigate the region of validity of this approximation. Insight arising from the analysis can be invaluable in the development and study of UV systems, as demonstrated by numerical results that illustrate implications of the analysis. PMID:24322923
Dynamic path analysis in life-course epidemiology.
Gamborg, Michael; Jensen, Gorm Boje; Sørensen, Thorkild I A; Andersen, Per Kragh
2011-05-15
Life-course epidemiology seeks to better understand the mechanisms that lead to the development of chronic diseases. An example is the mechanism leading from body size to coronary heart disease (CHD); one way to acquire a better understanding of this mechanism is to investigate to what extent it works through other risk factors. In this paper, the dynamic path analysis model is presented as a tool to analyze these dynamic mechanisms in life-course epidemiology. A key feature of dynamic path analysis is its ability to decompose the total effect of a risk factor into a direct effect (not mediated by other variables) and indirect effects (mediated through other variables). This is illustrated by examining the associations between repeated measurements of body mass index (BMI) and systolic blood pressure (SBP) and the risk of CHD in a sample of Danish men between 1976 and 2006. The effect of baseline BMI on the risk of CHD is decomposed into a direct effect and indirect effects going through later BMI, concurrent SBP, or later SBP. In conclusion, dynamic path analysis is a flexible tool that by the decomposition of effects can be used to increase the understanding of mechanisms that underlie the etiology of chronic disease. PMID:21415031
Correlates of romantic attachment: A path analysis study.
Shea, J A; Adams, G R
1984-02-01
A path-analytic study was undertaken to investigate the proposed relationship between physical attractiveness, need for intimacy, self-disclosure, thought about one's dating partner, and reported romantic love. Extrapolations from theories by Murstein (1971) and I. Reiss (1960), and conclusions from other empirical work, provided the background for the assessment of the relationship between the four proposed predictive factors and the development of romantic affect. During the winter of 1977-78 656 college students responded to a survey assessing each of the four predictors and romantic love. Path structures were initially estimated for male and female subsamples. Since few significant sex differences were noted, coefficients were compared for groups of students involved in dating relationships of varying durations. All four predictors were significantly associated with the subjects' self-reported romantic affect toward their dating partner. In all analyses, thinking about one's partner was found to be the most potent predictor. The data suggest the earlier work by Murstein and Reiss offer both testable and productive theoretical foundations for the study of romantic involvement. However, in future work it would be beneficial to (a) search for more numerous and powerful antecedents to romantic love; (b) delineate the specific role of cognitive processes in influencing romantic attachment; (c) compare relationships on criteria other than months of involvement; and (d) seek to examine love from the perspectives of both individuals involved in the dyadic relationship. PMID:24306506
Behavior analysis, mentalism, and the path to social justice
Moore, J.
2003-01-01
Traditional psychology is mentalistic in the sense that it appeals to inner causes in the explanation of behavior. Two examples of mentalism in traditional psychology are (a) dispositional attributions and (b) conventional treatments of intelligence. These examples may be linked to such pernicious social -isms as racism and sexism by noting that some individuals justify engaging in discriminatory conduct toward others by appealing to some deficient inner quality of those being discriminated against. This sort of mentalistic appeal ultimately prevents some members of our society from being integrated into society and from progressing down the path of social justice. Behavior analysis offers a constructional alternative to the mentalistic views of traditional psychology and allows our society as a whole to move down the path. PMID:22478401
Path Analysis of the Community Response to Road Traffic Noise
NASA Astrophysics Data System (ADS)
Osada, Y.; Yoshida, T.; Yoshida, K.; Kawaguchi, T.; Hoshiyama, Y.; Yamamoto, K.
1997-08-01
Path analysis was applied to data collected in a social survey on the community response to traffic noise along a trunk road in Tokyo. The data were collected from more than 390 female residents by means of a questionnaire. A path model was developed for the causal relation of the noise annoyance, dissatisfaction with living environment, and the wish of the respondents to move to the antecedent variables, including noise levels, personal factors, and noise effects. The strongest effect on annoyance was for the noise level, followed by interferences with daily activities. The model explains 43% of the variation in annoyance. The dissatisfaction with the living environment and wish of respondents to move depended strongly on noise annoyance, but other factors should also be considered, as only 33% and 19% of their variation, respectively, could be explained by the model.
Improvements in antenna coupling path algorithms for aircraft EMC analysis
NASA Astrophysics Data System (ADS)
Bogusz, Michael; Kibina, Stanley J.
The algorithms to calculate and display the path of maximum electromagnetic interference coupling along the perfectly conducting surface of a frustrum cone model of an aircraft nose are developed and revised for the Aircraft Inter-Antenna Propagation with Graphics (AAPG) electromagnetic compatibility analysis code. Analysis of the coupling problem geometry on the frustrum cone model and representative numerical test cases reveal how the revised algorithms are more accurate than their predecessors. These improvements in accuracy and their impact on realistic aircraft electromagnetic compatibility problems are outlined.
Zarabadi, Atefeh S; Pawliszyn, Janusz
2015-02-17
Analysis in the frequency domain is considered a powerful tool to elicit precise information from spectroscopic signals. In this study, the Fourier transformation technique is employed to determine the diffusion coefficient (D) of a number of proteins in the frequency domain. Analytical approaches are investigated for determination of D from both experimental and data treatment viewpoints. The diffusion process is modeled to calculate diffusion coefficients based on the Fourier transformation solution to Fick's law equation, and its results are compared to time domain results. The simulations characterize optimum spatial and temporal conditions and demonstrate the noise tolerance of the method. The proposed model is validated by its application for the electropherograms from the diffusion path of a set of proteins. Real-time dynamic scanning is conducted to monitor dispersion by employing whole column imaging detection technology in combination with capillary isoelectric focusing (CIEF) and the imaging plug flow (iPF) experiment. These experimental techniques provide different peak shapes, which are utilized to demonstrate the Fourier transformation ability in extracting diffusion coefficients out of irregular shape signals. Experimental results confirmed that the Fourier transformation procedure substantially enhanced the accuracy of the determined values compared to those obtained in the time domain. PMID:25607375
Analysis of Satellite Drag Coefficient Based on Wavelet Transform
NASA Astrophysics Data System (ADS)
Liu, Wei; Wang, Ronglan; Liu, Siqing
Abstract: Drag coefficient sequence was obtained by solving Tiangong1 continuous 55days GPS orbit data with different arc length. The same period solar flux f10.7 and geomagnetic index Ap ap series were high and low frequency multi-wavelet decomposition. Statistical analysis results of the layers sliding correlation between space environmental parameters and decomposition of Cd, showed that the satellite drag coefficient sequence after wavelet decomposition and the corresponding level of f10.7 Ap sequence with good lag correlation. It also verified that the Cd prediction is feasible. Prediction residuals of Cd with different regression models and different sample length were analysed. The results showed that the case was best when setting sample length 20 days and f10.7 regression model were used. It also showed that NRLMSIS-00 model's response in the region of 350km (Tiangong's altitude) and low-middle latitude (Tiangong's inclination) is excessive in ascent stage of geomagnetic activity Ap and is inadequate during fall off segment. Additionally, the low-frequency decomposition components NRLMSIS-00 model's response is appropriate in f10.7 rising segment. High frequency decomposition section, Showed NRLMSIS-00 model's response is small-scale inadequate during f10.7 ascent segment and is reverse in decline of f10.7. Finally, the potential use of a summary and outlook were listed; This method has an important reference value to improve the spacecraft orbit prediction accuracy. Key words: wavelet transform; drag coefficient; lag correlation; Tiangong1;space environment
Path-sensitive analysis for reducing rollback overheads
O'Brien, John K.P.; Wang, Kai-Ting Amy; Yamashita, Mark; Zhuang, Xiaotong
2014-07-22
A mechanism is provided for path-sensitive analysis for reducing rollback overheads. The mechanism receives, in a compiler, program code to be compiled to form compiled code. The mechanism divides the code into basic blocks. The mechanism then determines a restore register set for each of the one or more basic blocks to form one or more restore register sets. The mechanism then stores the one or more register sets such that responsive to a rollback during execution of the compiled code. A rollback routine identifies a restore register set from the one or more restore register sets and restores registers identified in the identified restore register set.
Coefficient of variation spectral analysis: An application to underwater acoustics
NASA Astrophysics Data System (ADS)
Herstein, P. D.; Laplante, R. F.
1983-05-01
Acoustic noise in the ocean is often described in terms of its power spectral density. Just as in other media, this noise consists of both narrowband and broadband frequency components. A major problem in the analysis of power spectral density measurements is distinguishing between narrowband spectral components of interest and contaminating narrowband components. In this paper, the use of coefficient of variation (Cv) spectrum is examined as an adjunct to the conventional power spectrum to distinguish narrowband components of interest from contaminating components. The theory of the Cv is presented. Coefficients for several classical input distributions are developed. It is shown that Cv spectra can be easily implemented as an adjunct procedure during the computation of the ensemble of averaged power spectra. Power and Cv spectra derived from actual at-sea sonobuoy measurements of deep ocean ambient noise separate narrowband components from narrowband lines of interest in the ensemble of averaged power spectra, these acoustic components of interest can be distinguished in the Cv spectra.
Analysis of the contact graph routing algorithm: Bounding interplanetary paths
NASA Astrophysics Data System (ADS)
Birrane, Edward; Burleigh, Scott; Kasch, Niels
2012-06-01
Interplanetary communication networks comprise orbiters, deep-space relays, and stations on planetary surfaces. These networks must overcome node mobility, constrained resources, and significant propagation delays. Opportunities for wireless contact rely on calculating transmit and receive opportunities, but the Euclidean-distance diameter of these networks (measured in light-seconds and light-minutes) precludes node discovery and contact negotiation. Propagation delay may be larger than the line-of-sight contact between nodes. For example, Mars and Earth orbiters may be separated by up to 20.8 min of signal propagation time. Such spacecraft may never share line-of-sight, but may uni-directionally communicate if one orbiter knows the other's future position. The Contact Graph Routing (CGR) approach is a family of algorithms presented to solve the messaging problem of interplanetary communications. These algorithms exploit networks where nodes exhibit deterministic mobility. For CGR, mobility and bandwidth information is pre-configured throughout the network allowing nodes to construct transmit opportunities. Once constructed, routing algorithms operate on this contact graph to build an efficient path through the network. The interpretation of the contact graph, and the construction of a bounded approximate path, is critically important for adoption in operational systems. Brute force approaches, while effective in small networks, are computationally expensive and will not scale. Methods of inferring cycles or other librations within the graph are difficult to detect and will guide the practical implementation of any routing algorithm. This paper presents a mathematical analysis of a multi-destination contact graph algorithm (MD-CGR), demonstrates that it is NP-complete, and proposes realistic constraints that make the problem solvable in polynomial time, as is the case with the originally proposed CGR algorithm. An analysis of path construction to complement hop
NASA Astrophysics Data System (ADS)
Yan, Yangqian; Blume, D.
2016-06-01
The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b4 of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4 , our b4 agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions.
Yan, Yangqian; Blume, D
2016-06-10
The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astrophysics. This work determines the fourth-order virial coefficient b_{4} of such a strongly interacting Fermi gas using a customized ab initio path-integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b_{4}, our b_{4} agrees within error bars with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly antisymmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions. PMID:27341213
NASA Astrophysics Data System (ADS)
Yan, Yangqian; Blume, D.
2016-05-01
The unitary equal-mass Fermi gas with zero-range interactions constitutes a paradigmatic model system that is relevant to atomic, condensed matter, nuclear, particle, and astro physics. This work determines the fourth-order virial coefficient b4 of such a strongly-interacting Fermi gas using a customized ab inito path integral Monte Carlo (PIMC) algorithm. In contrast to earlier theoretical results, which disagreed on the sign and magnitude of b4, our b4 agrees with the experimentally determined value, thereby resolving an ongoing literature debate. Utilizing a trap regulator, our PIMC approach determines the fourth-order virial coefficient by directly sampling the partition function. An on-the-fly anti-symmetrization avoids the Thomas collapse and, combined with the use of the exact two-body zero-range propagator, establishes an efficient general means to treat small Fermi systems with zero-range interactions. We gratefully acknowledge support by the NSF.
Path analysis of agro-industrial traits in sweet sorghum.
Lombardi, G M R; Nunes, J A R; Parrella, R A C; Teixeira, D H L; Bruzi, A T; Durães, N N L; Fagundes, T G
2015-01-01
Sweet sorghum has considerable potential for ethanol production due to its succulent stalks that contain directly fermentable sugars. Since many traits need to be considered in the selection process to breed superior cultivars for ethanol production, then correlations between the traits might be of use to help the breeder define optimal improvement strategies. The aim of this study was to investigate the association between the principal agro-industrial traits in sweet sorghum, and to evaluate the direct and indirect effects of primary and secondary traits on ethanol production per hectare. In total, 45 sweet sorghum genotypes (lineage/hybrids) were evaluated in an experiment designed in an alpha lattice 5 x 9. The data were analyzed using a mixed model approach. A detailed study of simple correlations was accomplished using path analysis. The experimental precision was high, with an accuracy above 76%. The various genotypes showed genetic variation for all agronomic and industrial traits, except stalk diameter. Some agro-industrial traits showed significant simple correlations with ethanol production, but according to the path analysis, some of these traits did not show a significant direct or indirect effect on ethanol production. The results highlighted the primary and secondary traits with practical relevance to sweet sorghum breeding, since they showed director indirect effects on ethanol production. PMID:26662435
Soil Organic Matter Effects on Phosphorus Sorption: a Path Analysis
Kang, J.; Hesterberg, D; Osmond, D
2009-01-01
While P sorption in mineral soils has been extensively studied, P sorption behavior in organic-rich soils is less known. This study was conducted to determine the relationships between Langmuir P sorption maxima (S{sub max}) and selected physicochemical properties of soils, with particular emphasis on organic matter (OM) content. The S{sub max} values were determined for 72 soil samples from the North Carolina Coastal Plain, along with pH, clay and OM contents, oxalate-extractable P (P{sub ox}), Al (Al{sub ox}), and Fe (Fe{sub ox}), and Mehlich 3 extractable P (P{sub M3}), Al (Al{sub M3}), and Fe (Fe{sub M3}). Path analysis was used to examine direct and indirect effects of soil properties on S{sub max}. In the oxalate path analysis, the direct effects of clay, Al{sub ox}, and Fe{sub ox} on S{sub max} were significant in the order Al{sub ox} > clay > Fe{sub ox} (P < 0.05). The S{sub max} was highly influenced by the indirect effect of Al{sub ox} and Fe{sub ox} through OM content. A two-piece segmented linear relationship existed between S{sub max} and OM and the regression slope in soils with OM {le} 49 g kg{sup -1} was 10-fold greater than that for soils with OM > 49 g kg{sup -1}. This finding suggested that noncrystalline or organically bound Al and Fe in the soils with OM > 49 g kg{sup -1} is less effective for P sorption than in the soils with lower OM content. In the Mehlich 3 path analysis, the direct effects of clay, OM, and Al{sub M3} on S{sub max} were significant in the order Al{sub M3} > OM > clay (P < 0.05) while the direct effect of Fe{sub M3} on S{sub max} was not significant. Oxalate may be better suited than Mehlich 3 as an extractant for predicting P sorption capacity in the Coastal Plain soils.
Quantifying tight-gas sandstone permeability via critical path analysis
NASA Astrophysics Data System (ADS)
Ghanbarian, Behzad; Torres-Verdín, Carlos; Skaggs, Todd H.
2016-06-01
Rock permeability has been actively investigated over the past several decades by the geosciences community. However, its accurate estimation still presents significant technical challenges, particularly in spatially complex rocks. In this short communication, we apply critical path analysis (CPA) to estimate permeability in porous rocks from measured mercury intrusion porosimetry and electrical conductivity data. Theoretical estimations of various CPA-based models are then compared to experimental measurements using eighteen tight-gas sandstones. Except for two of the samples, we find permeability estimations performed with the Skaggs model (assuming pore diameter independent of its length) more accurate than other models, within a factor of two of the measured permeabilities. We discuss some plausible sources of the uncertainties.
Path Analysis of Household Energy Use - Neighborhood Comparison
NASA Astrophysics Data System (ADS)
Tenjin, Nanako
Many have studied residential energy use in relation with appliance types and efficiency, dwelling types, behavior, socio-demographics, and geography. Yet little is understood about the interrelations among the variables in the context of energy use. We used data collected through residential energy surveys from two neighborhoods in California. Path analysis models with emphasis on the appliance characteristics, appliance usage, and household energy use were developed and statistically tested. Our study showed that even a simple demographic variable like household size has unique effect channels on household energy use and also the channel was significant in one neighborhood but not in the other. While our model leaves much to be improved, the model supports a framework of energy use to explain energy use from a behavioral perspective in which household decisions were related to socio-demographic characteristics but neighborhood difference also plays a major role.
NASA Astrophysics Data System (ADS)
Mobile, Michael; Widdowson, Mark; Stewart, Lloyd; Nyman, Jennifer; Deeb, Rula; Kavanaugh, Michael; Mercer, James; Gallagher, Daniel
2016-04-01
Better estimates of non-aqueous phase liquid (NAPL) mass, its persistence into the future, and the potential impact of source reduction are critical needs for determining the optimal path to clean up sites impacted by NAPLs. One impediment to constraining time estimates of source depletion is the uncertainty in the rate of mass transfer between NAPLs and groundwater. In this study, an innovative field test is demonstrated for the purpose of quantifying field-scale NAPL mass transfer coefficients (klN) within a source zone of a fuel-contaminated site. Initial evaluation of the test concept using a numerical model revealed that the aqueous phase concentration response to the injection of clean groundwater within a source zone was a function of NAPL mass transfer. Under rate limited conditions, NAPL dissolution together with the injection flow rate and the radial distance to monitoring points directly controlled time of travel. Concentration responses observed in the field test were consistent with the hypothetical model results allowing field-scale NAPL mass transfer coefficients to be quantified. Site models for groundwater flow and solute transport were systematically calibrated and utilized for data analysis. Results show klN for benzene varied from 0.022 to 0.60 d- 1. Variability in results was attributed to a highly heterogeneous horizon consisting of layered media of varying physical properties.
Mobile, Michael; Widdowson, Mark; Stewart, Lloyd; Nyman, Jennifer; Deeb, Rula; Kavanaugh, Michael; Mercer, James; Gallagher, Daniel
2016-04-01
Better estimates of non-aqueous phase liquid (NAPL) mass, its persistence into the future, and the potential impact of source reduction are critical needs for determining the optimal path to clean up sites impacted by NAPLs. One impediment to constraining time estimates of source depletion is the uncertainty in the rate of mass transfer between NAPLs and groundwater. In this study, an innovative field test is demonstrated for the purpose of quantifying field-scale NAPL mass transfer coefficients (kl(N)) within a source zone of a fuel-contaminated site. Initial evaluation of the test concept using a numerical model revealed that the aqueous phase concentration response to the injection of clean groundwater within a source zone was a function of NAPL mass transfer. Under rate limited conditions, NAPL dissolution together with the injection flow rate and the radial distance to monitoring points directly controlled time of travel. Concentration responses observed in the field test were consistent with the hypothetical model results allowing field-scale NAPL mass transfer coefficients to be quantified. Site models for groundwater flow and solute transport were systematically calibrated and utilized for data analysis. Results show kl(N) for benzene varied from 0.022 to 0.60d(-1). Variability in results was attributed to a highly heterogeneous horizon consisting of layered media of varying physical properties. PMID:26855386
Application of critical path analysis in clinical trials
Kumar, Amal; Chakraborty, Bhaswat S.
2016-01-01
Clinical research operates in a strictly regulated environment under various management models, but a distinct management model of clinical trial (CT) still needs exploration and research. Critical path analysis (CPA) is a management approach can be used for monitoring, analysis, and prediction of success of its time-bound operational activities. A model CT was compiled with 78 activities, which were further merged into 35 major activities. After performing dependence analysis, the list was finalized with 25 activities which were taken in activity predecessor to create a network diagram and perform CPA considering patients, conduct, and outcome. Activities were inclusive, described the trial entirely with accuracy, and were in chronological and logical sequences. This approach does not replace an understanding of or adherence to the requirements contained in all applicable regulations, guidelines or standard operating procedures governing clinical studies but ensures the proper use of operational and decisional approaches including optimal resource management. As the need to meet deadlines becomes more important and the need to produce good, stable project plans, CPA is very useful for determining activities that can lead to project delay. With this approach, project may be effectively monitored, and realistic schedules can be maintained. PMID:26955606
Application of critical path analysis in clinical trials.
Kumar, Amal; Chakraborty, Bhaswat S
2016-01-01
Clinical research operates in a strictly regulated environment under various management models, but a distinct management model of clinical trial (CT) still needs exploration and research. Critical path analysis (CPA) is a management approach can be used for monitoring, analysis, and prediction of success of its time-bound operational activities. A model CT was compiled with 78 activities, which were further merged into 35 major activities. After performing dependence analysis, the list was finalized with 25 activities which were taken in activity predecessor to create a network diagram and perform CPA considering patients, conduct, and outcome. Activities were inclusive, described the trial entirely with accuracy, and were in chronological and logical sequences. This approach does not replace an understanding of or adherence to the requirements contained in all applicable regulations, guidelines or standard operating procedures governing clinical studies but ensures the proper use of operational and decisional approaches including optimal resource management. As the need to meet deadlines becomes more important and the need to produce good, stable project plans, CPA is very useful for determining activities that can lead to project delay. With this approach, project may be effectively monitored, and realistic schedules can be maintained. PMID:26955606
TRAC (Transient Reactor Analysis Code) model of reactor vent paths
Pevey, R.E.; Reece, J.W.
1987-12-18
The Safety Methods group of Scientific Computations Division (SCD) is currently calculating assembly power limits based on reactor response to a double-ended guillotine pipe break loss of coolant accident (LOCA). SCD has implemented a two-level approach in which the Transient Reactor Analysis Code (TRAC) is used to calculate the system pressure response to the LOCA, and these pressures serve as the boundary conditions for a detailed assembly calculation using FLOWTRAN. As part of the TRAC calculation, a detailed TRAC model of the reactor vent paths has been developed that involves the hardware in the top portion of the reactor tank through which air flows as the moderator tank drains following the LOCA initiation. The hardware included in this model are the top shield (with its many penetrations), the gas space above the top shield, the vacuum breakers, the U tube, the helium blanket gas system, and the gas ports. This detailed model is necessary for an accurate calculation of the tank pressures in the first few seconds of the LOCA because the initial tank depressurization is relieved through these vent paths. The tank pressures for about 5 seconds into the transient are sensitive to water flow from the gas space through the top shield, the associated expansion pressure drop of the blanket gas, and the clearing of the vacuum breakers and gas ports. This model was added to a previously developed TRAC model of the rest of the system and the resulting full system model was used to calculate the pressure response during the first few seconds of the LOCA. 8 refs., 8 figs.
Transition path theory analysis of c-Src kinase activation.
Meng, Yilin; Shukla, Diwakar; Pande, Vijay S; Roux, Benoît
2016-08-16
Nonreceptor tyrosine kinases of the Src family are large multidomain allosteric proteins that are crucial to cellular signaling pathways. In a previous study, we generated a Markov state model (MSM) to simulate the activation of c-Src catalytic domain, used as a prototypical tyrosine kinase. The long-time kinetics of transition predicted by the MSM was in agreement with experimental observations. In the present study, we apply the framework of transition path theory (TPT) to the previously constructed MSM to characterize the main features of the activation pathway. The analysis indicates that the activating transition, in which the activation loop first opens up followed by an inward rotation of the αC-helix, takes place via a dense set of intermediate microstates distributed within a fairly broad "transition tube" in a multidimensional conformational subspace connecting the two end-point conformations. Multiple microstates with negligible equilibrium probabilities carry a large transition flux associated with the activating transition, which explains why extensive conformational sampling is necessary to accurately determine the kinetics of activation. Our results suggest that the combination of MSM with TPT provides an effective framework to represent conformational transitions in complex biomolecular systems. PMID:27482115
Ghosal, Dipak; Mueller, Stephen Ng
2005-04-01
With multipath routing in mobile ad hoc networks (MANETs), a source can establish multiple routes to a destination for routing data. In MANETs, mulitpath routing can be used to provide route resilience, smaller end-to-end delay, and better load balancing. However, when the multiple paths are close together, transmissions of different paths may interfere with each other, causing degradation in performance. Besides interference, the physical diversity of paths also improves fault tolerance. We present a purely distributed multipath protocol based on the AODV-Multipath (AODVM) protocol called AODVM with Path Diversity (AODVM/PD) that finds multiple paths with a desired degree of correlation between paths specified as an input parameter to the algorithm. We demonstrate through detailed simulation analysis that multiple paths with low degree of correlation determined by AODVM/PD provides both smaller end-to-end delay than AODVM in networks with low mobility and better route resilience in the presence of correlated node failures.
Causal Modeling--Path Analysis a New Trend in Research in Applied Linguistics
ERIC Educational Resources Information Center
Rastegar, Mina
2006-01-01
This article aims at discussing a new statistical trend in research in applied linguistics. This rather new statistical procedure is causal modeling--path analysis. The article demonstrates that causal modeling--path analysis is the best statistical option to use when the effects of a multitude of L2 learners' variables on language achievement are…
Using Parcels to Convert Path Analysis Models into Latent Variable Models
ERIC Educational Resources Information Center
Coffman, Donna L.; MacCallum, Robert C.
2005-01-01
The biasing effects of measurement error in path analysis models can be overcome by the use of latent variable models. In cases where path analysis is used in practice, it is often possible to use parcels as indicators of a latent variable. The purpose of the current study was to compare latent variable models in which parcels were used as…
NASA Astrophysics Data System (ADS)
Wei, Linsheng; Xu, Min; Yuan, Dingkun; Zhang, Yafang; Hu, Zhaoji; Tan, Zhihong
2014-10-01
The electron drift velocity, electron energy distribution function (EEDF), density-normalized effective ionization coefficient and density-normalized longitudinal diffusion velocity are calculated in SF6-O2 and SF6-Air mixtures. The experimental results from a pulsed Townsend discharge are plotted for comparison with the numerical results. The reduced field strength varies from 40 Td to 500 Td (1 Townsend=10-17 V·cm2) and the SF6 concentration ranges from 10% to 100%. A Boltzmann equation associated with the two-term spherical harmonic expansion approximation is utilized to gain the swarm parameters in steady-state Townsend. Results show that the accuracy of the Boltzmann solution with a two-term expansion in calculating the electron drift velocity, electron energy distribution function, and density-normalized effective ionization coefficient is acceptable. The effective ionization coefficient presents a distinct relationship with the SF6 content in the mixtures. Moreover, the E/Ncr values in SF6-Air mixtures are higher than those in SF6-O2 mixtures and the calculated value E/Ncr in SF6-O2 and SF6-Air mixtures is lower than the measured value in SF6-N2. Parametric studies conducted on these parameters using the Boltzmann analysis offer substantial insight into the plasma physics, as well as a basis to explore the ozone generation process.
Ste-Marie, Diane M; Carter, Michael J; Law, Barbi; Vertes, Kelly; Smith, Victoria
2016-09-01
Research has shown learning advantages for self-controlled practice contexts relative to yoked (i.e., experimenter-imposed) contexts; yet, explanations for this phenomenon remain relatively untested. We examined, via path analysis, whether self-efficacy and intrinsic motivation are important constructs for explaining self-controlled learning benefits. The path model was created using theory-based and empirically supported relationships to examine causal links between these psychological constructs and physical performance. We hypothesised that self-efficacy and intrinsic motivation would have greater predictive power for learning under self-controlled compared to yoked conditions. Participants learned double-mini trampoline progressions, and measures of physical performance, self-efficacy and intrinsic motivation were collected over two practice days and a delayed retention day. The self-controlled group (M = 2.04, SD = .98) completed significantly more skill progressions in retention than their yoked counterparts (M = 1.3, SD = .65). The path model displayed adequate fit, and similar significant path coefficients were found for both groups wherein each variable was predominantly predicted by its preceding time point (e.g., self-efficacy time 1 predicts self-efficacy time 2). Interestingly, the model was not moderated by group; thus, failing to support the hypothesis that self-efficacy and intrinsic motivation have greater predictive power for learning under self-controlled relative to yoked conditions. PMID:26707002
ERIC Educational Resources Information Center
Phillips, Gary W.
The usefulness of path analysis as a means of better understanding various linear models is demonstrated. First, two linear models are presented in matrix form using linear structural relations (LISREL) notation. The two models, regression and factor analysis, are shown to be identical although the research question and data matrix to which these…
The solubility of (Ba,Sr)SO 4 precipitates: Thermodynamic equilibrium and reaction path analysis
NASA Astrophysics Data System (ADS)
Felmy, Andrew R.; Rai, Dhanpat; Moore, Dean A.
1993-09-01
The solubility of (Ba,Sr)SO 4 precipitates, varying in SrSO 4 mole fraction from 0.05-0.90, was investigated at room temperature with an equilibration period extending to almost three years. The data show that on or before 315 days of equilibration the precipitates reach a reversible equilibrium with the aqueous solution. The reversibility of this equilibrium was verified both by the attainment of steady-state concentrations with time and by heating the samples to perturb the equilibrium and then observing the slow return to the initial equilibrium state. The dissolution of the (Ba,Sr)SO 4 precipitates does not, in general, follow limiting reaction paths as defined by the Lippmann solutus or stoichiometric dissolution curves. In addition, activity coefficient calculations for the BaSO 4 and SrSO 4 components of the solid phase, using either total bulk analysis or near-surface analysis of the component mole fractions, do not satisfy the Gibbs-Duhem equation, demonstrating that a single solid-solution phase does not control both the aqueous Ba and Sr concentrations. Instead, our long-term equilibration data can be explained by the unavoidable formation of small amounts of barite and substitution of Sr into a solid-solution phase with the BaSO 4 component of the solid-solution phase never reaching thermodynamic equilibrium with the aqueous phase.
NASA Astrophysics Data System (ADS)
Merz, Ralf; BlöSchl, Günter
2009-01-01
In this paper we analyze the controls on the spatiotemporal variability of event runoff coefficients. A total of about 64,000 events in 459 Austrian catchments ranging from 5 to 10000 km2 are analyzed. Event runoff coefficients vary in space, depending on the long-term controls such as climate and catchment formation. Event runoff coefficients also vary in time, depending on event characteristics such as antecedent soil moisture and event rainfall depth. Both types of controls are analyzed separately in the paper. The spatial variability is analyzed in terms of a correlation analysis of the statistical moments of the runoff coefficients and catchment attributes. Mean runoff coefficients are most strongly correlated to indicators representing climate such as mean annual precipitation and the long-term ratio of actual evaporation to precipitation through affecting long-term soil moisture. Land use, soil types, and geology do not seem to exert a major control on runoff coefficients of the catchments under study. The temporal variability is analyzed by comparing the deviation of the event runoff coefficients from their mean depending on event characteristics. The analysis indicates that antecedent soil moisture conditions control runoff coefficients to a higher degree than does event rainfall. The analysis also indicates that soil moisture derived from soil moisture accounting schemes has more predictive power for the temporal variability of runoff coefficients than antecedent rainfall.
CONGR: A FORTRAN IV Program to Compute Coefficients of Congruence for Factor Analysis
ERIC Educational Resources Information Center
Myers, Donald E.
1976-01-01
A Fortran IV program which computes either of the coefficients of congruence (psi or phi) used in comparison of factors in factor analysis is presented. Output consists of a non-symmetric matrix of factor coefficients. Listings of the program, results and test data are available. (Author/JKS)
The development and analysis of geopotential coefficient models to spherical harmonic degree 360
NASA Astrophysics Data System (ADS)
Rapp, Richard H.; Pavlis, Nikolaos K.
1990-12-01
Two new geopotential coefficient models to spherical harmonic degree 360 are developed using recent advances made in theoretical modeling methods, satellite gravitational models, and expanded and improved terrestrial data. The new models are based on the combination of a satellite potential coefficient model (GEM-T2) to degree 50 with 30-arc mean gravity anomalies, yielding an adjusted set of coefficients and gravity anomalies, which were then harmonically analyzed to yield a set of potential coefficients to degree 360. The models were verified in several ways including satellite orbit residual analysis, demonstrating a substantial improvement over previous high-degree expansions.
The development and analysis of geopotential coefficient models to spherical harmonic degree 360
NASA Technical Reports Server (NTRS)
Rapp, Richard H.; Pavlis, Nikolaos K.
1990-01-01
Two new geopotential coefficient models to spherical harmonic degree 360 are developed using recent advances made in theoretical modeling methods, satellite gravitational models, and expanded and improved terrestrial data. The new models are based on the combination of a satellite potential coefficient model (GEM-T2) to degree 50 with 30-arc mean gravity anomalies, yielding an adjusted set of coefficients and gravity anomalies, which were then harmonically analyzed to yield a set of potential coefficients to degree 360. The models were verified in several ways including satellite orbit residual analysis, demonstrating a substantial improvement over previous high-degree expansions.
An improved path flux analysis with multi generations method for mechanism reduction
NASA Astrophysics Data System (ADS)
Wang, Wei; Gou, Xiaolong
2016-03-01
An improved path flux analysis with a multi generations (IMPFA) method is proposed to eliminate unimportant species and reactions, and to generate skeletal mechanisms. The production and consumption path fluxes of each species at multiple reaction paths are calculated and analysed to identify the importance of the species and of the elementary reactions. On the basis of the indexes of each reaction path of the first, second, and third generations, the improved path flux analysis with two generations (IMPFA2) and improved path flux analysis with three generations (IMPFA3) are used to generate skeletal mechanisms that contain different numbers of species. The skeletal mechanisms are validated in the case of homogeneous autoignition and perfectly stirred reactor of methane and n-decane/air mixtures. Simulation results of the skeletal mechanisms generated by IMPFA2 and IMPFA3 are compared with those obtained by path flux analysis (PFA) with two and three generations, respectively. The comparisons of ignition delay times, final temperatures, and temperature dependence on flow residence time show that the skeletal mechanisms generated by the present IMPFA method are more accurate than those obtained by the PFA method, with almost the same number of species under a range of initial conditions. By considering the accuracy and computational efficiency, when using the IMPFA (or PFA) method, three generations may be the best choice for the reduction of large-scale detailed chemistry.
Impact of Maternal Death on Household Economy in Rural China: A Prospective Path Analysis
Ye, Fang; Ao, Deng; Feng, Yao; Wang, Lin; Chen, Jie; Huntington, Dale
2015-01-01
Objectives The present study aimed to explore the inter-relationships among maternal death, household economic status after the event, and potential influencing factors. Methods We conducted a prospective cohort study of households that had experienced maternal death (n = 195) and those that experienced childbirth without maternal death (n = 384) in rural China. All the households were interviewed after the event occurred and were followed up 12 months later. Structural equation modeling was used to test the relationship model, utilizing income and expenditure per capita in the following year after the event as the main outcome variables, maternal death as the predictor, and direct costs, the amount of money offset by positive and negative coping strategies, whether the husband remarried, and whether the newborn was alive as the mediators. Results In the following year after the event, the path analysis revealed a direct effect from maternal death to lower income per capita (standardized coefficient = -0.43, p = 0.041) and to lower expenditure per capita (standardized coefficient = -0.51, p<0.001). A significant indirect effect was found from maternal death to lower income and expenditure per capita mediated by the influencing factors of higher direct costs, less money from positive coping methods, more money from negative coping, and the survival of the newborn. Conclusion This study analyzed the direct and indirect effects of maternal death on a household economy. The results provided evidence for better understanding the mechanism of how this event affects a household economy and provided a reference for social welfare policies to target the most vulnerable households that have suffered from maternal deaths. PMID:26247210
Genome-scale cluster analysis of replicated microarrays using shrinkage correlation coefficient
Yao, Jianchao; Chang, Chunqi; Salmi, Mari L; Hung, Yeung Sam; Loraine, Ann; Roux, Stanley J
2008-01-01
Background Currently, clustering with some form of correlation coefficient as the gene similarity metric has become a popular method for profiling genomic data. The Pearson correlation coefficient and the standard deviation (SD)-weighted correlation coefficient are the two most widely-used correlations as the similarity metrics in clustering microarray data. However, these two correlations are not optimal for analyzing replicated microarray data generated by most laboratories. An effective correlation coefficient is needed to provide statistically sufficient analysis of replicated microarray data. Results In this study, we describe a novel correlation coefficient, shrinkage correlation coefficient (SCC), that fully exploits the similarity between the replicated microarray experimental samples. The methodology considers both the number of replicates and the variance within each experimental group in clustering expression data, and provides a robust statistical estimation of the error of replicated microarray data. The value of SCC is revealed by its comparison with two other correlation coefficients that are currently the most widely-used (Pearson correlation coefficient and SD-weighted correlation coefficient) using statistical measures on both synthetic expression data as well as real gene expression data from Saccharomyces cerevisiae. Two leading clustering methods, hierarchical and k-means clustering were applied for the comparison. The comparison indicated that using SCC achieves better clustering performance. Applying SCC-based hierarchical clustering to the replicated microarray data obtained from germinating spores of the fern Ceratopteris richardii, we discovered two clusters of genes with shared expression patterns during spore germination. Functional analysis suggested that some of the genetic mechanisms that control germination in such diverse plant lineages as mosses and angiosperms are also conserved among ferns. Conclusion This study shows that SCC is
Uncertainty Analysis of Seebeck Coefficient and Electrical Resistivity Characterization
NASA Technical Reports Server (NTRS)
Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred
2014-01-01
In order to provide a complete description of a materials thermoelectric power factor, in addition to the measured nominal value, an uncertainty interval is required. The uncertainty may contain sources of measurement error including systematic bias error and precision error of a statistical nature. The work focuses specifically on the popular ZEM-3 (Ulvac Technologies) measurement system, but the methods apply to any measurement system. The analysis accounts for sources of systematic error including sample preparation tolerance, measurement probe placement, thermocouple cold-finger effect, and measurement parameters; in addition to including uncertainty of a statistical nature. Complete uncertainty analysis of a measurement system allows for more reliable comparison of measurement data between laboratories.
Multidimensional stock network analysis: An Escoufier's RV coefficient approach
NASA Astrophysics Data System (ADS)
Lee, Gan Siew; Djauhari, Maman A.
2013-09-01
The current practice of stocks network analysis is based on the assumption that the time series of closed stock price could represent the behaviour of the each stock. This assumption leads to consider minimal spanning tree (MST) and sub-dominant ultrametric (SDU) as an indispensible tool to filter the economic information contained in the network. Recently, there is an attempt where researchers represent stock not only as a univariate time series of closed price but as a bivariate time series of closed price and volume. In this case, they developed the so-called multidimensional MST to filter the important economic information. However, in this paper, we show that their approach is only applicable for that bivariate time series only. This leads us to introduce a new methodology to construct MST where each stock is represented by a multivariate time series. An example of Malaysian stock exchange will be presented and discussed to illustrate the advantages of the method.
Path Length Entropy Analysis of Diastolic Heart Sounds
Griffel, B.; Zia, M. K.; Fridman, V.; Saponieri, C.; Semmlow, J. L.
2013-01-01
Early detection of coronary artery disease (CAD) using the acoustic approach, a noninvasive and cost-effective method, would greatly improve the outcome of CAD patients. To detect CAD, we analyze diastolic sounds for possible CAD murmurs. We observed diastolic sounds to exhibit 1/f structure and developed a new method, path length entropy (PLE) and a scaled version (SPLE), to characterize this structure to improve CAD detection. We compare SPLE results to Hurst exponent, Sample entropy and Multi-scale entropy for distinguishing between normal and CAD patients. SPLE achieved a sensitivity-specificity of 80%–81%, the best of the tested methods. However, PLE and SPLE are not sufficient to prove nonlinearity, and evaluation using surrogate data suggests that our cardiovascular sound recordings do not contain significant nonlinear properties. PMID:23930808
Abraham, Michael H; Gil-Lostes, Javier; Corr, Stuart; Acree, William E
2012-11-23
Gas-water partition coefficients, K(w), and gas-solvent partition coefficients, K(s), have been determined for chlorodifluoromethane and for 1,1,1,3,3,3-hexafluoropropane by headspace analysis, using a very simple experimental procedure. These partition coefficients then yield water-solvent partition coefficients, P(s). Where comparisons can be made there is excellent agreement with literature values for K(w) and P(s). The obtained values of K(s) and P(s) can be used to obtain physicochemical properties, or descriptors, for the refrigerants. Combination of these descriptors with previous equations we have developed enables partition coefficients to be obtained for a host of systems. PMID:23089519
Pawel, David; Leggett, Richard Wayne; Eckerman, Keith F; Nelson, Christopher
2007-01-01
Federal Guidance Report No. 13 (FGR 13) provides risk coefficients for estimation of the risk of cancer due to low-level exposure to each of more than 800 radionuclides. Uncertainties in risk coefficients were quantified in FGR 13 for 33 cases (exposure to each of 11 radionuclides by each of three exposure pathways) on the basis of sensitivity analyses in which various combinations of plausible biokinetic, dosimetric, and radiation risk models were used to generate alternative risk coefficients. The present report updates the uncertainty analysis in FGR 13 for the cases of inhalation and ingestion of radionuclides and expands the analysis to all radionuclides addressed in that report. The analysis indicates that most risk coefficients for inhalation or ingestion of radionuclides are determined within a factor of 5 or less by current information. That is, application of alternate plausible biokinetic and dosimetric models and radiation risk models (based on the linear, no-threshold hypothesis with an adjustment for the dose and dose rate effectiveness factor) is unlikely to change these coefficients by more than a factor of 5. In this analysis the assessed uncertainty in the radiation risk model was found to be the main determinant of the uncertainty category for most risk coefficients, but conclusions concerning the relative contributions of risk and dose models to the total uncertainty in a risk coefficient may depend strongly on the method of assessing uncertainties in the risk model.
Global Qualitative Flow-Path Modeling for Local State Determination in Simulation and Analysis
NASA Technical Reports Server (NTRS)
Malin, Jane T. (Inventor); Fleming, Land D. (Inventor)
1998-01-01
For qualitative modeling and analysis, a general qualitative abstraction of power transmission variables (flow and effort) for elements of flow paths includes information on resistance, net flow, permissible directions of flow, and qualitative potential is discussed. Each type of component model has flow-related variables and an associated internal flow map, connected into an overall flow network of the system. For storage devices, the implicit power transfer to the environment is represented by "virtual" circuits that include an environmental junction. A heterogeneous aggregation method simplifies the path structure. A method determines global flow-path changes during dynamic simulation and analysis, and identifies corresponding local flow state changes that are effects of global configuration changes. Flow-path determination is triggered by any change in a flow-related device variable in a simulation or analysis. Components (path elements) that may be affected are identified, and flow-related attributes favoring flow in the two possible directions are collected for each of them. Next, flow-related attributes are determined for each affected path element, based on possibly conflicting indications of flow direction. Spurious qualitative ambiguities are minimized by using relative magnitudes and permissible directions of flow, and by favoring flow sources over effort sources when comparing flow tendencies. The results are output to local flow states of affected components.
Women's Paths in Science: A Critical Feminist Analysis
ERIC Educational Resources Information Center
Kinzie, Jillian
2007-01-01
The author introduces her critical and feminist perspective, elaborates on her critical approach, and discusses how this influenced the development of her research questions, methodology, data analysis, interpretation, and presentation of findings.
Someswara Rao, Chinta; Viswanadha Raju, S
2016-03-01
In this paper, we consider correlation coefficient, rank correlation coefficient and cosine similarity measures for evaluating similarity between Homo sapiens and monkeys. We used DNA chromosomes of genome wide genes to determine the correlation between the chromosomal content and evolutionary relationship. The similarity among the H. sapiens and monkeys is measured for a total of 210 chromosomes related to 10 species. The similarity measures of these different species show the relationship between the H. sapiens and monkey. This similarity will be helpful at theft identification, maternity identification, disease identification, etc. PMID:26981409
NASA Astrophysics Data System (ADS)
Wang, Gufeng; Karnes, John; Bunker, Christopher E.; Lei Geng, M.
2006-11-01
We demonstrate the feasibility of using two-dimensional correlation coefficient mapping to classify gas chromatograms of environmental hazards. Correct identification and classification of the contaminants is the prerequisite for their appropriate treatment and containments. A data set consisting of 76 gas chromatograms of eight types of jet fuels, which are common sources of hydrocarbon contamination in ground water, is examined with two-dimensional statistical sample-sample correlation coefficients. Analysis demonstrates that jet fuel samples of the same type correlate strongly with each other but less significantly with other jet fuel classes. According to the magnitude of the correlation coefficients between each pair of the samples, jet fuel types of each sample in the data set can be assigned with an accuracy of 100% through a leave-one-out cross validation (LOOCV) procedure. Correlation coefficient mapping is thus a promising method to classify samples of environmental importance.
Ranking paths in statistical energy analysis models with non-deterministic loss factors
NASA Astrophysics Data System (ADS)
Aragonès, Àngels; Guasch, Oriol
2015-02-01
Finding the contributions of transmission paths in statistical energy analysis (SEA) models has become an established valuable tool to detect and remedy vibro-acoustic problems. Paths are identified in SEA according to Craik's definition and recently, very efficient methods have been derived to rank them in the framework of graph theory. However, up to date classification schemes have only considered the mean values of loss factors for path comparison, their variance being ignored. This can result in significant errors in the final results. In this work it is proposed to address this problem by defining stochastic biparametric SEA graphs whose edges are assigned both, mean and variance values. Paths between subsystems are then compared according to a proposed cost function that accounts for the stochastic nature of loss factors. For an efficacious ranking of paths, the stochastic SEA graph is converted to an extended deterministic SEA graph where fast classification deterministic algorithms can be applied. The importance of nonneglecting the influence of the variance in path ranking is illustrated by means of some academic numerical examples.
An Optimization-Driven Analysis Pipeline to Uncover Biomarkers and Signaling Paths: Cervix Cancer
Lorenzo, Enery; Camacho-Caceres, Katia; Ropelewski, Alexander J.; Rosas, Juan; Ortiz-Mojer, Michael; Perez-Marty, Lynn; Irizarry, Juan; Gonzalez, Valerie; Rodríguez, Jesús A.; Cabrera-Rios, Mauricio; Isaza, Clara
2015-01-01
Establishing how a series of potentially important genes might relate to each other is relevant to understand the origin and evolution of illnesses, such as cancer. High-throughput biological experiments have played a critical role in providing information in this regard. A special challenge, however, is that of trying to conciliate information from separate microarray experiments to build a potential genetic signaling path. This work proposes a two-step analysis pipeline, based on optimization, to approach meta-analysis aiming to build a proxy for a genetic signaling path. PMID:26388997
Automatic Beam Path Analysis of Laser Wakefield Particle Acceleration Data
Rubel, Oliver; Geddes, Cameron G.R.; Cormier-Michel, Estelle; Wu, Kesheng; Prabhat,; Weber, Gunther H.; Ushizima, Daniela M.; Messmer, Peter; Hagen, Hans; Hamann, Bernd; Bethel, E. Wes
2009-10-19
Numerical simulations of laser wakefield particle accelerators play a key role in the understanding of the complex acceleration process and in the design of expensive experimental facilities. As the size and complexity of simulation output grows, an increasingly acute challenge is the practical need for computational techniques that aid in scientific knowledge discovery. To that end, we present a set of data-understanding algorithms that work in concert in a pipeline fashion to automatically locate and analyze high energy particle bunches undergoing acceleration in very large simulation datasets. These techniques work cooperatively by first identifying features of interest in individual timesteps, then integrating features across timesteps, and based on the information derived perform analysis of temporally dynamic features. This combination of techniques supports accurate detection of particle beams enabling a deeper level of scientific understanding of physical phenomena than hasbeen possible before. By combining efficient data analysis algorithms and state-of-the-art data management we enable high-performance analysis of extremely large particle datasets in 3D. We demonstrate the usefulness of our methods for a variety of 2D and 3D datasets and discuss the performance of our analysis pipeline.
Analysis of the ACTS-Vancouver Path Propagation Data
NASA Technical Reports Server (NTRS)
Kharadly, M.; Ross, R.; Dow, B.
1996-01-01
The data described here cover the two-year period from 1 December 1993 to 30 November, 1995. The analysis is done for two sets of valid data: (a) observed or total attenuation data, which includes all atmospheric effects plus the additional attenuation resulting from wet antenna surfaces during rain events, and (b) adjusted attenuation data as in (a) minus estimated values of attenuation due to wetting the antenna surfaces. In both cases, average and worst month cumulative distribution functions (CDF's), fade-duration statistics, and fade-slope statistics for the 20 and 27 GHz beacons are presented.
NASA Astrophysics Data System (ADS)
Jones, Reese E.; Mandadapu, Kranthi K.
2012-04-01
We present a rigorous Green-Kubo methodology for calculating transport coefficients based on on-the-fly estimates of: (a) statistical stationarity of the relevant process, and (b) error in the resulting coefficient. The methodology uses time samples efficiently across an ensemble of parallel replicas to yield accurate estimates, which is particularly useful for estimating the thermal conductivity of semi-conductors near their Debye temperatures where the characteristic decay times of the heat flux correlation functions are large. Employing and extending the error analysis of Zwanzig and Ailawadi [Phys. Rev. 182, 280 (1969)], 10.1103/PhysRev.182.280 and Frenkel [in Proceedings of the International School of Physics "Enrico Fermi", Course LXXV (North-Holland Publishing Company, Amsterdam, 1980)] to the integral of correlation, we are able to provide tight theoretical bounds for the error in the estimate of the transport coefficient. To demonstrate the performance of the method, four test cases of increasing computational cost and complexity are presented: the viscosity of Ar and water, and the thermal conductivity of Si and GaN. In addition to producing accurate estimates of the transport coefficients for these materials, this work demonstrates precise agreement of the computed variances in the estimates of the correlation and the transport coefficient with the extended theory based on the assumption that fluctuations follow a Gaussian process. The proposed algorithm in conjunction with the extended theory enables the calculation of transport coefficients with the Green-Kubo method accurately and efficiently.
Thomas, S; Fell, D A
1993-06-01
A computer program (MetaCon) is described for the evaluation of flux control, concentration control and branch-point distribution control coefficients of a metabolic pathway. Requiring only the reaction scheme as input, the program produces algebraic expressions for the control coefficients in terms of elasticity coefficients, metabolite concentrations and pathway fluxes. Any of these variables can be substituted by numeric or simple algebraic expressions; the expressions will then be automatically rearranged in terms of the remaining unknown variables. When all variables have been substituted, numeric values will be obtained for the control coefficients. The program is a computerized implementation of the matrix method for the determination of control coefficients. The features of MetaCon are compared with those of other programs available to workers in Metabolic Control Analysis. Potential benefits of, and methods of using, MetaCon are discussed. The mathematical background and validity of the matrix method rules are discussed, and the algorithm used by MetaCon is described. The matrix method is shown to be a specific case of a previously described general formalism for calculating control coefficients. PMID:8503870
NASA Astrophysics Data System (ADS)
Kim, B.; Eun, S.; Seo, W.; Park, J.; Ahn, J.; Moon, K.
2013-12-01
Aerosols in the atmosphere can scatter and absorb solar radiation and their spatial/temporal distributions are highly inhomogeneous due to short lifetimes (about a few weeks or less). Through scattering and absorption of solar radiation, aerosols directly affect visibility and climate through the modification of the Earth's energy budget (Charlson et al., 1992; Yan, 2007; Wang, 2012). This study investigates long-term trends and characteristics of aerosol light scattering coefficient at Seoul and Baengnyeongdo, 100 km upstream of Seoul, in Korea. Aerosol scattering coefficients were measured continuously with nephelometers. The analysis period is limited to one year of 2011. For the relationship analysis of extinction coefficients (σext) to visibility and aerosol optical depth, σsp observed at 3 p.m. have been used with help of aerosol absorption coefficients (σap) in order to remove its dependence upon relative humidity (RH), and also those of rainy period have been excluded. As expected, σext estimated are inversely proportional to visibility observation by eye. Aerosol extinction coefficients have been vertically integrated with an assumption of nearly well-mixed within an e-folding height to determine aerosol optical depth (τa), and compared with those retrieved from sunphotometer. The results show a reasonable agreement in spite of an inherent difference of each definition. We expect these findings would help to eventually understand aerosol radiative forcing and its effect on the regional climate change around Korea.
NASA Astrophysics Data System (ADS)
Hirasawa, T.; Ishihara, M.; Tsujita, K.; Hirota, K.; Irisawa, K.; Kitagaki, M.; Fujita, M.; Kikuchi, M.
2012-02-01
In photo-acoustic (PA) imaging, valuable medical applications based on optical absorption spectrum such as contrast agent imaging and blood oxygen saturation measurement have been investigated. In these applications, there is an essential requirement to determine optical absorption coefficients accurately. In present, PA signal intensities have been commonly used to determine optical absorption coefficients. This method achieves practical accuracy by combining with radiative transfer analysis. However, time consumption of radiative transfer analysis and effects of signal generation efficiencies were problems of this method. In this research, we propose a new method to determine optical absorption coefficients using continuous wavelet transform (CWT). We used CWT to estimate instantaneous frequencies of PA signals which reflects optical absorption distribution. We validated the effectiveness of CWT in determination of optical absorption coefficients through an experiment. In the experiment, planar shaped samples were illuminated to generate PA signal. The PA signal was measured by our fabricated PA probe in which an optical fiber and a ring shaped P(VDFTrFE) ultrasound sensor were coaxially aligned. Optical properties of samples were adjusted by changing the concentration of dye solution. Tunable Ti:Sapphire laser (690 - 1000 nm) was used as illumination source. As a result, we confirmed strong correlation between optical absorption coefficients of samples and the instantaneous frequency of PA signal obtained by CWT. Advantages of this method were less interference of light transfer and signal generation efficiency.
Analysis of the Lagrangian path structures in fluid turbulence
NASA Astrophysics Data System (ADS)
Wang, Lipo
2014-04-01
Because in the Lagrangian frame the time scale separation has a stronger Reynolds number dependence than the length scale case in the Eulerian frame, it is more difficult to reveal inertial range scaling laws, as predicted from dimensional arguments. The present work introduces a newly defined trajectory segment structure to tentatively understand Lagrangian statistics. When a fluid particle evolves in space, its Lagrangian trajectory encounters regions of different dynamics, which can be characterized by the magnitude of material acceleration, i.e., |a|, in certain time span. The extrema of |a| are considered as the representative markers along the Lagrangian trajectories. A trajectory segment is defined as the part bounded by two adjacent extrema of |a|. The time difference and magnitude of the velocity difference at the two ends of each segment are chosen as the characteristic parameters. It shows that such structure reveals interesting turbulence physics, such as the scaling of the structure function and the quantitative description of the time scale. The corresponding explanation and analysis of flow physics are provided as well to improve the understanding of some remaining challenging issues.
ERIC Educational Resources Information Center
Hurd, Noelle M.; Stoddard, Sarah A.; Zimmerman, Marc A.
2013-01-01
This study explored how neighborhood characteristics may relate to African American adolescents' internalizing symptoms via adolescents' social support and perceptions of neighborhood cohesion. Participants included 571 urban, African American adolescents (52% female; "M" age = 17.8). A multilevel path analysis testing both direct and indirect…
Mathematics Teaching Anxiety and Self-Efficacy Beliefs toward Mathematics Teaching: A Path Analysis
ERIC Educational Resources Information Center
Peker, Murat
2016-01-01
The purpose of this study was to investigate the relationship between pre-service primary school teachers' mathematics teaching anxiety and their self-efficacy beliefs toward mathematics teaching through path analysis. There were a total of 250 pre-service primary school teachers involved in this study. Of the total, 202 were female and 48 were…
ERIC Educational Resources Information Center
Brown, Steven D.; Lent, Robert W.; Telander, Kyle; Tramayne, Selena
2011-01-01
We performed a meta-analytic path analysis of an abbreviated version of social cognitive career theory's (SCCT) model of work performance (Lent, Brown, & Hackett, 1994). The model we tested included the central cognitive predictors of performance (ability, self-efficacy, performance goals), with the exception of outcome expectations. Results…
Errata to the Werts-Linn Comments on Boyle's "Path Analysis and Ordinal Data."
ERIC Educational Resources Information Center
Werts, Charles E.; Linn, Robert L.
The Werts-Linn procedure for dealing with categorical errors of measurement in "Comments on Boyle's 'Path Analysis and Ordinal Data'" in The American Journal of Sociology, volume 76, number 6, May 1971, is shown to be inappropriate to the problem of ordered categories. (For related document, see TM 002 301.) (DB)
A Path Analysis of Social Problem-Solving as a Predictor of White Racial Identity
ERIC Educational Resources Information Center
Carr, Amanda G.; Caskie, Grace I. L.
2010-01-01
This study examined (a) whether a developmental model or a model in which all subscales' measurement errors are correlated best explains the relationships among White racial identity (WRI) statuses, and (b) social problem-solving (SPS) skills as a predictor of WRI. Path analysis was conducted with a sample of 255 White undergraduate students from…
Psychometric Inferences from a Meta-Analysis of Reliability and Internal Consistency Coefficients
ERIC Educational Resources Information Center
Botella, Juan; Suero, Manuel; Gambara, Hilda
2010-01-01
A meta-analysis of the reliability of the scores from a specific test, also called reliability generalization, allows the quantitative synthesis of its properties from a set of studies. It is usually assumed that part of the variation in the reliability coefficients is due to some unknown and implicit mechanism that restricts and biases the…
Evaluation of Reliability Coefficients for Two-Level Models via Latent Variable Analysis
ERIC Educational Resources Information Center
Raykov, Tenko; Penev, Spiridon
2010-01-01
A latent variable analysis procedure for evaluation of reliability coefficients for 2-level models is outlined. The method provides point and interval estimates of group means' reliability, overall reliability of means, and conditional reliability. In addition, the approach can be used to test simple hypotheses about these parameters. The…
NASA Astrophysics Data System (ADS)
Hannemann, Klaus; Karl, Sebastian; Martinez Schramm, Jan; Steelant, Johan
2010-10-01
In the framework of the European Commission co-funded LAPCAT (Long-Term Advanced Propulsion Concepts and Technologies) project, the methodology of a combined ground-based testing and numerical modelling analysis of supersonic combustion flow paths was established. The approach is based on free jet testing of complete supersonic combustion ramjet (scramjet) configurations consisting of intake, combustor and nozzle in the High Enthalpy Shock Tunnel Göttingen (HEG) of the German Aerospace Center (DLR) and computational fluid dynamics studies utilising the DLR TAU code. The capability of the established methodology is demonstrated by applying it to the flow path of the generic HyShot II scramjet flight experiment configuration.
NASA Astrophysics Data System (ADS)
Wang, Gang-Jin; Xie, Chi; Chen, Shou; Yang, Jiao-Jiao; Yang, Ming-Yan
2013-09-01
In this study, we first build two empirical cross-correlation matrices in the US stock market by two different methods, namely the Pearson’s correlation coefficient and the detrended cross-correlation coefficient (DCCA coefficient). Then, combining the two matrices with the method of random matrix theory (RMT), we mainly investigate the statistical properties of cross-correlations in the US stock market. We choose the daily closing prices of 462 constituent stocks of S&P 500 index as the research objects and select the sample data from January 3, 2005 to August 31, 2012. In the empirical analysis, we examine the statistical properties of cross-correlation coefficients, the distribution of eigenvalues, the distribution of eigenvector components, and the inverse participation ratio. From the two methods, we find some new results of the cross-correlations in the US stock market in our study, which are different from the conclusions reached by previous studies. The empirical cross-correlation matrices constructed by the DCCA coefficient show several interesting properties at different time scales in the US stock market, which are useful to the risk management and optimal portfolio selection, especially to the diversity of the asset portfolio. It will be an interesting and meaningful work to find the theoretical eigenvalue distribution of a completely random matrix R for the DCCA coefficient because it does not obey the Marčenko-Pastur distribution.
Automatic clustering and population analysis of white matter tracts using maximum density paths.
Prasad, Gautam; Joshi, Shantanu H; Jahanshad, Neda; Villalon-Reina, Julio; Aganj, Iman; Lenglet, Christophe; Sapiro, Guillermo; McMahon, Katie L; de Zubicaray, Greig I; Martin, Nicholas G; Wright, Margaret J; Toga, Arthur W; Thompson, Paul M
2014-08-15
We introduce a framework for population analysis of white matter tracts based on diffusion-weighted images of the brain. The framework enables extraction of fibers from high angular resolution diffusion images (HARDI); clustering of the fibers based partly on prior knowledge from an atlas; representation of the fiber bundles compactly using a path following points of highest density (maximum density path; MDP); and registration of these paths together using geodesic curve matching to find local correspondences across a population. We demonstrate our method on 4-Tesla HARDI scans from 565 young adults to compute localized statistics across 50 white matter tracts based on fractional anisotropy (FA). Experimental results show increased sensitivity in the determination of genetic influences on principal fiber tracts compared to the tract-based spatial statistics (TBSS) method. Our results show that the MDP representation reveals important parts of the white matter structure and considerably reduces the dimensionality over comparable fiber matching approaches. PMID:24747738
Vulnerabilities, Influences and Interaction Paths: Failure Data for Integrated System Risk Analysis
NASA Technical Reports Server (NTRS)
Malin, Jane T.; Fleming, Land
2006-01-01
We describe graph-based analysis methods for identifying and analyzing cross-subsystem interaction risks from subsystem connectivity information. By discovering external and remote influences that would be otherwise unexpected, these methods can support better communication among subsystem designers at points of potential conflict and to support design of more dependable and diagnosable systems. These methods identify hazard causes that can impact vulnerable functions or entities if propagated across interaction paths from the hazard source to the vulnerable target. The analysis can also assess combined impacts of And-Or trees of disabling influences. The analysis can use ratings of hazards and vulnerabilities to calculate cumulative measures of the severity and importance. Identification of cross-subsystem hazard-vulnerability pairs and propagation paths across subsystems will increase coverage of hazard and risk analysis and can indicate risk control and protection strategies.
First order analysis of the effect of pitching on the drag coefficient
Wilson, R.E.; Neff, J.A.
1985-11-01
A first order analysis was made for the drag coefficient of a pitching NACA 0015 airfoil below stall. The inviscid velocity ditribution for a translating NACA 0015 airfoil was superimposed with the additional circulation velocity for a pitching ellipse. The resulting velocity distribution was used to numerically integrate a momentum/boundary layer formulation to obtain the drag coefficient. For both laminar and turbulent boundary layers it was found that the effect of pitching on the drag coefficient can be approximated by a shift in angle of attack. The shift angle was found to be a linear function of the pitching velocity and to be less than the induced angle of attack caused by the pitching.
Analysis for leakage and rotordynamic coefficients of surface roughened tapered annular gas seals
NASA Technical Reports Server (NTRS)
Nelson, C. C.
1984-01-01
In order to soften the effects of rub, the smooth stators of turbine gas seals are sometimes replaced by a honeycomb surface. This deliberately roughened stator and smooth rotor combination retards the seal leakage and may lead to enhanced rotor stability. However, many factors determine the rotordynamic coefficients and little is known as to the effectiveness of these honeycomb seals under various changes in the independent seal parameters. An analytical-computational method to solve for the rotordynamic coefficients of this type of compressible-flow seal is developed. The governing equations for surface roughned tapered annular gas seals are based on a modified Hirs' turbulent bulk flow model. A perturbation analysis is employed to develop zeroth and first-order perturbation equations. These equations are numerically integrated to solve for the leakage, pressure, density, and velocity for small motion of the shaft about the centered position. The resulting pressure distribution is then integrated to find the corresponding rotor-dynamic coefficients.
NASA Technical Reports Server (NTRS)
Nelson, C. C.; Nguyen, D. T.
1987-01-01
A new analysis procedure has been presented which solves for the flow variables of an annular pressure seal in which the rotor has a large static displacement (eccentricity) from the centered position. The present paper incorporates the solutions to investigate the effect of eccentricity on the rotordynamic coefficients. The analysis begins with a set of governing equations based on a turbulent bulk-flow model and Moody's friction factor equation. Perturbations of the flow variables yields a set of zeroth- and first-order equations. After integration of the zeroth-order equations, the resulting zeroth-order flow variables are used as input in the solution of the first-order equations. Further integration of the first order pressures yields the eccentric rotordynamic coefficients. The results from this procedure compare well with available experimental and theoretical data, with accuracy just as good or slightly better than the predictions based on a finite-element model.
Random effects coefficient of determination for mixed and meta-analysis models.
Demidenko, Eugene; Sargent, James; Onega, Tracy
2012-01-01
The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, [Formula: see text], that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If [Formula: see text] is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of [Formula: see text] apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects-the model can be estimated using the dummy variable approach. We derive explicit formulas for [Formula: see text] in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine. PMID:23750070
NASA Astrophysics Data System (ADS)
Briz, Susana; Diez, Sarai; de Castro, Antonio J.; Lopez, Fernando; Schafer, Klaus
2004-11-01
Fourier Transform Infrared (FTIR) spectroscopy is a well-established technique for monitoring air pollutants by extractive methods. Remote sensing by Open-Path FTIR technique incorporates the advantages of a non-intrusive technique. EPA and VDI have recommended some guidelines for the application of this promising technique. However, it is necessary to do more research to assess the quality of these systems on the basis of European standards. The analysis of FTIR spectra are usually carried out by using methods based on classical least squares (CLS) procedures. In this work a line-by-line method (SFIT) is additionally used. SFIT is a non-linear least-squares fitting program that was designed to analyse solar absorption spectra. For this work, SFIT has been adapted and applied to Open-Path FTIR spectra. The objective of this work is to study the capability of both methods to analyse open-path measurements of carbon monoxide. From a previous work it was inferred that the selection of the analysis spectral window is a relevant parameter of SFIT analysis. Therefore, the first step has been to analyse synthetic spectra of known concentration to select the best spectral region and other parameters of analysis. Afterwards, the SFIT software has been applied to Open-Path experimental spectra. Results of the SFIT method have been compared with the results of the two methods of EVAL analysis. EVAL is a commercial software (provided with the instrument) that is based on a CLS procedure and on the absorption peak intensity. The result has been validated by comparison to a standard extractive method.
NASA Astrophysics Data System (ADS)
Guasch, Oriol; García, Carlos; Jové, Jordi; Artís, Pere
2013-05-01
Transmissibility functions have received renewed interest given the important role they play in operational modal analysis and operational transfer path analysis. However, transmissibilities can also be used in the framework of classical transmission path analysis. This avoids some of the problems associated to the latter, such as the measurement of operational loads, or the need to remove the active parts of the system to measure frequency response functions. The key of the transmissibility approach to classical transfer path analysis relies on the notion of direct or blocked transmissibilities, which can be computed from standard measurable transmissibilities. The response at any degree of freedom to a system external load can then be decomposed in terms of the remaining degrees of freedom responses and the system direct transmissibilities. Although the theory supporting this approach has been known for long, no experimental validation test has been reported to date. It is the purpose of this paper to provide such a test by applying the method to a simple mechanical system for which an analytical solution can be derived. For different configurations, it will be shown that direct transmissibilities computed from measured transmissibilities compare fairly well with analytical results. This opens the door to apply the method to more complex situations of practical interest with confidence.
Gibson, LaTosha M; Gopalan, Balaji; Pisupati, Sarma V; Shadle, Lawrence J
2013-10-01
New robust Lagrangian computational fluid dynamic (CFD) models are powerful tools that can be used to study the behavior of a diverse population of coal particle sizes, densities, and mineral compositions in entrained gasifiers. By using this approach, the responses of the particles impacting the wall were characterized over a range of velocities (1 to 8 m/s) and incident angles (90 to 20°). Within CFD models, the kinematic coefficient of restitution is the boundary condition defining the particle wall behavior. Four surfaces were studied to simulate the physical conditions of different entrained-flow gasification particle–surface collision scenarios: 1) a flat metal plate 2) a low viscosity silicon adhesive, 3) a high viscosity silicon adhesive, and 4) adhered particles on a flat metal plate with Young's modulus of elasticity ranging from 0.9 to 190 GPa. Entrained flow and drop experiments were conducted with granular coke particles, polyethylene beads and polystyrene pellets. The particle normal and tangential coefficients of restitution were measured using high speed imaging and particle tracking. The measured coefficients of restitution were observed to have a strong dependence on the rebound angles for most of the data. Suitable algebraic expressions for the normal and the tangential component of the coefficient of restitution were developed based upon ANOVA analysis. These expressions quantify the effect of normalized Young's modulus, particle equancy, and relative velocity on the coefficient of restitution. The coefficient of restitution did not have a strong dependence on the particle velocity over the range considered as long as the velocity was above the critical velocity. However, strong correlations were found between the degree of equancy of the particles and the mean coefficient of restitution such that the coefficient of restitution decreased for smaller particle equancies. It was concluded that the degree of equancy and the normalized Young
Izumi, Tatsuya; Hagiwara, Manabu; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki
2012-08-01
We developed a possible method to determine both coefficients of piezoelectricity (d) and electrostriction (M) at the same time by a waveform analysis of current and vibration velocity in the resonance state. The waveforms of the current and vibration velocity were theoretically described using the equations of motion and piezoelectric constitutive equations, considering the dissipation effect. The dissipation factor of the d coefficient and M coefficient is dielectric loss tangent tan δ. The waveforms measured in all of the ceramics, such as Pb(Zr,Ti)O(3) (PZT), Pb(Mg,Nb)O(3) (PMN), and 0.8Pb(Mg(1/3)Nb2/3)O(3)-0.2PbTiO(3) (PMN-PT), were well fitted with the calculated waveform. This fitting produced both the d and M coefficients, which agreed with those determined via the conventional methods. Moreover, the respective contributions of both piezoelectricity and electrostriction to the d value determined in the resonance-antiresonance method were clarified. PMID:22899111
Automatic Match between Delimitation Line and Real Terrain Based on Least-Cost Path Analysis
NASA Astrophysics Data System (ADS)
Feng, C. Q.; Jiang, N.; Zhang, X. N.; Ma, J.
2013-11-01
Nowadays, during the international negotiation on separating dispute areas, manual adjusting is lonely applied to the match between delimitation line and real terrain, which not only consumes much time and great labor force, but also cannot ensure high precision. Concerning that, the paper mainly explores automatic match between them and study its general solution based on Least -Cost Path Analysis. First, under the guidelines of delimitation laws, the cost layer is acquired through special disposals of delimitation line and terrain features line. Second, a new delimitation line gets constructed with the help of Least-Cost Path Analysis. Third, the whole automatic match model is built via Module Builder in order to share and reuse it. Finally, the result of automatic match is analyzed from many different aspects, including delimitation laws, two-sided benefits and so on. Consequently, a conclusion is made that the method of automatic match is feasible and effective.
Houtveen, Jan H; Hamaker, Ellen L; Van Doornen, Lorenz J P
2010-05-01
A non-clinical group high on heterogeneous medically unexplained symptoms (MUS; n=97) was compared with healthy controls (n=66) on the within-subject relationships between physiological measures using multilevel path analysis. Momentary experienced somatic complaints, mood (tension and depression), cardiac autonomic activity (inter-beat intervals, pre-ejection period (PEP), and respiratory sinus arrhythmia (RSA)) and respiration (rate and partial pressure of CO(2) at the end of a normal expiration) were monitored for 24 h using electronic diary and ambulatory devices. Relationships between measures were controlled for diurnal variation and individual means. Only subtle group differences were found in the diurnal rhythm and in the within-subject relationships between physiological measures. For participants high on MUS, within-subject changes in bodily symptoms were related to changes in mood, but only marginally to the physiological measures. Results of the current path analysis confirm the subordinate role of cardiac autonomic and respiratory parameters in MUS. PMID:20030762
In-situ source path contribution analysis of structure borne road noise
NASA Astrophysics Data System (ADS)
Elliott, A. S.; Moorhouse, A. T.; Huntley, T.; Tate, S.
2013-11-01
Source-path-contribution (SPC) analysis, also known as transfer path analysis (TPA), is a technique widely used in the automotive industry for rank ordering noise and vibration sources. The SPC approach is known to provide reliable diagnostic information but is time consuming to apply. In this paper, a faster SPC approach that allows all measurements to be performed in-situ is outlined and tested. For validation purposes a classic example consisting of a vehicle's suspension system (considered a vibration source) attached to a vehicle body (receiver) is analysed. It is found that structure borne noise inside the vehicle can be predicted well by either the conventional or the novel in-situ SPC approaches and that both methods give the same diagnostic information in terms of the rank ordering of path contributions. Thus, the new in-situ approach provides results at least as reliable as the conventional inverse SPC approach but has significant practical advantages in terms of reduced test time, transferability of data and flexibility in the location of the source-receiver interface. An additional investigation also demonstrates the feasibility of including rotational motions and moments in the analysis and it is shown that improved accuracy can be achieved as a result.
NASA Astrophysics Data System (ADS)
Dyadkin, A. A.; Khatuntseva, O. N.
2014-12-01
Analysis of experimental data shows that the nature of the oscillating motion of an aircraft does not depend uniquely on the value of the coefficients of aerodynamic damping derivatives. The present work makes an attempt to explain this phenomenon and develops a methodology to adequately characterize the oscillating motion of aircraft based on the analysis of the coefficients of aerodynamic damping derivatives.
ERIC Educational Resources Information Center
Morcol, Goktug; McLaughlin, Gerald W.
1990-01-01
The study proposes using path analysis and residual plotting as methods supporting environmental scanning in strategic planning for higher education institutions. Path models of three levels of independent variables are developed. Dependent variables measuring applications and enrollments at Virginia Polytechnic Institute and State University are…
A Run-Length Encoding Approach for Path Analysis of C. elegans Search Behavior
Kim, Hongkyun; Furst, Jacob
2016-01-01
The nematode Caenorhabditis elegans explores the environment using a combination of different movement patterns, which include straight movement, reversal, and turns. We propose to quantify C. elegans movement behavior using a computer vision approach based on run-length encoding of step-length data. In this approach, the path of C. elegans is encoded as a string of characters, where each character represents a path segment of a specific type of movement. With these encoded string data, we perform k-means cluster analysis to distinguish movement behaviors resulting from different genotypes and food availability. We found that shallow and sharp turns are the most critical factors in distinguishing the differences among the movement behaviors. To validate our approach, we examined the movement behavior of tph-1 mutants that lack an enzyme responsible for serotonin biosynthesis. A k-means cluster analysis with the path string-encoded data showed that tph-1 movement behavior on food is similar to that of wild-type animals off food. We suggest that this run-length encoding approach is applicable to trajectory data in animal or human mobility data. PMID:27462364
NASA Astrophysics Data System (ADS)
Dirba, I.; Kleperis, J.
2011-01-01
Analytical and numerical modelling is performed for the linear actuator of a parallel path magnet motor. In the model based on finite-element analysis, the 3D problem is reduced to a 2D problem, which is sufficiently precise in a design aspect and allows modelling the principle of a parallel path motor. The paper also describes a relevant numerical model and gives comparison with experimental results. The numerical model includes all geometrical and physical characteristics of the motor components. The magnetic flux density and magnetic force are simulated using FEMM 4.2 software. An experimental model has also been developed and verified for the core of switchable magnetic flux linear actuator and motor. The results of experiments are compared with those of theoretical/analytical and numerical modelling.
Morphological Awareness in Literacy Acquisition of Chinese Second Graders: A Path Analysis.
Zhang, Haomin
2016-02-01
The present study tested a path diagram regarding the contribution of morphological awareness (MA) to early literacy acquisition among Chinese-speaking second graders ([Formula: see text]). Three facets of MA were addressed, namely derivational awareness, compound awareness and compound structure awareness. The model aimed to test a theory of causal order among measures of MA and literacy outcomes. Drawing upon multivariate path analysis, direct and indirect effects of MA were analyzed to identify their role in literacy performance among young children. Results revealed that all three facets of MA made significant contributions to lexical inference ability. In addition, compound awareness showed a unique and significant contribution to vocabulary knowledge. It was also observed that lexical inference ability had a mediating effect predictive of both vocabulary knowledge and reading comprehension. Moreover, vocabulary knowledge mediated the effect of MA on reading comprehension. However, no significant contribution of MA to reading comprehension was found after controlling for lexical inference ability and vocabulary knowledge. PMID:25308872
NASA Astrophysics Data System (ADS)
Lee, Woo-Jin; Kang, Se-Ryong; Choi, Soon-Chul; Lee, Sam-Sun; Heo, Min-Suk; Huh, Kyung-Hoe; Yi, Won-Jin
2016-07-01
The objective of this study was to develop a spectral CT system using a photon counting detector and to decompose materials by applying a multiple discriminant analysis (MDA) to the energy-dependent attenuation coefficient ratios. We imaged cylindrical phantoms of Polymethyl methacrylate (PMMA) with four holes filled with calcium chloride, iodine, and gold nanoparticle contrast agents. The attenuation coefficients were measured via reconstructed multi-energy images, and the linear attenuation ratio was used for material identification. The MDA projection matrix, determined from training phantoms, was used to identify the four materials in the testing phantoms. For quantification purposes, the relationships between the attenuation coefficients at multiple energy bins and the concentrations were characterized by using the least-squares method for each material. The mean identification accuracy for each of the three materials were 0.94 ± 0.09 for iodine, 0.96 ± 0.07 for gold nanoparticles, and 0.92 ± 0.05 for calcium chloride. The mean quantification errors were 1.90 ± 1.58% for iodine, 3.85 ± 3.13% for gold nanoparticle, and 3.40 ± 2.62% for calcium chloride. The developed multi-energy CT system based on the photon-counting detector with MDA can precisely decompose the four materials.
NASA Astrophysics Data System (ADS)
Chai, Bing-Bing; Vass, Jozsef; Zhuang, Xinhua
1997-04-01
Recent success in wavelet coding is mainly attributed to the recognition of importance of data organization. There has been several very competitive wavelet codecs developed, namely, Shapiro's Embedded Zerotree Wavelets (EZW), Servetto et. al.'s Morphological Representation of Wavelet Data (MRWD), and Said and Pearlman's Set Partitioning in Hierarchical Trees (SPIHT). In this paper, we propose a new image compression algorithm called Significant-Linked Connected Component Analysis (SLCCA) of wavelet coefficients. SLCCA exploits both within-subband clustering of significant coefficients and cross-subband dependency in significant fields. A so-called significant link between connected components is designed to reduce the positional overhead of MRWD. In addition, the significant coefficients' magnitude are encoded in bit plane order to match the probability model of the adaptive arithmetic coder. Experiments show that SLCCA outperforms both EZW and MRWD, and is tied with SPIHT. Furthermore, it is observed that SLCCA generally has the best performance on images with large portion of texture. When applied to fingerprint image compression, it outperforms FBI's wavelet scalar quantization by about 1 dB.
Jiang, Zhaolin; Shen, Nuo; Zhou, Jianwei
2013-01-01
We first give the style spectral decomposition of a special skew circulant matrix C and then get the style decomposition of arbitrary skew circulant matrix by making use of the Kronecker products between the elements of first row in skew circulant and the special skew circulant C. Besides that, we obtain the singular value of skew circulant matrix as well. Finally, we deal with the optimal backward perturbation analysis for the linear system with skew circulant coefficient matrix on the base of its style spectral decomposition. PMID:24369488
NASA Astrophysics Data System (ADS)
Tang, M. J.; Shiraiwa, M.; Poschl, U.; Cox, R. A.; Kalberer, M.
2015-05-01
Diffusion of organic vapours to the surface of aerosol or cloud particles is an important step for the formation and transformation of atmospheric particles. So far, however, a database of gas phase diffusion coefficients for organic compounds of atmospheric interest has not been available. In this work we have compiled and evaluated gas phase diffusivities (pressure-independent diffusion coefficients) of organic compounds reported by previous experimental studies, and we compare the measurement data to estimates obtained with Fuller's semi-empirical method. The difference between measured and estimated diffusivities are mostly < 10%. With regard to gas-particle interactions, different gas molecules, including both organic and inorganic compounds, exhibit similar Knudsen numbers (Kn) although their gas phase diffusivities may vary over a wide range. This is because different trace gas molecules have similar mean free paths in air at a given pressure. Thus, we introduce the pressure-normalised mean free path, λP ~ 100 nm atm, as a near-constant generic parameter that can be used for approximate calculation of Knudsen numbers as a simple function of gas pressure and particle diameter to characterise the influence of gas phase diffusion on the uptake of gases by aerosol or cloud particles. We use a kinetic multilayer model of gas-particle interaction to illustrate the effects of gas phase diffusion on the condensation of organic compounds with different volatilities. The results show that gas phase diffusion can play a major role in determining the growth of secondary organic aerosol particles by condensation of low-volatility organic vapours.
Correlations and path analysis among agronomic and technological traits of upland cotton.
Farias, F J C; Carvalho, L P; Silva Filho, J L; Teodoro, P E
2016-01-01
To date, path analysis has been used with the aim of breeding different cultures. However, for cotton, there have been few studies using this analysis, and all of these have used fiber productivity as the primary dependent variable. Therefore, the aim of the present study was to identify agronomic and technological properties that can be used as criteria for direct and indirect phenotypes in selecting cotton genotypes with better fibers. We evaluated 16 upland cotton genotypes in eight trials conducted during the harvest 2008/2009 in the State of Mato Grosso, using a randomized block design with four replicates. The evaluated traits were: plant height, average boll weight, percentage of fiber, cotton seed yield, fiber length, uniformity of fiber, short fiber index, fiber strength, elongation, maturity of the fibers, micronaire, reflectance, and the degree of yellowing. Phenotypic correlations between the traits and cotton fiber yield (main dependent variable) were unfolded in direct and indirect effects through path analysis. Fiber strength, uniformity of fiber, and reflectance were found to influence fiber length, and therefore, these traits are recommended for both direct and indirect selection of cotton genotypes. PMID:27525939
Free wake analysis of hover performance using a new influence coefficient method
NASA Technical Reports Server (NTRS)
Quackenbush, Todd R.; Bliss, Donald B.; Ong, Ching Cho; Ching, Cho Ong
1990-01-01
A new approach to the prediction of helicopter rotor performance using a free wake analysis was developed. This new method uses a relaxation process that does not suffer from the convergence problems associated with previous time marching simulations. This wake relaxation procedure was coupled to a vortex-lattice, lifting surface loads analysis to produce a novel, self contained performance prediction code: EHPIC (Evaluation of Helicopter Performance using Influence Coefficients). The major technical features of the EHPIC code are described and a substantial amount of background information on the capabilities and proper operation of the code is supplied. Sample problems were undertaken to demonstrate the robustness and flexibility of the basic approach. Also, a performance correlation study was carried out to establish the breadth of applicability of the code, with very favorable results.
NASA Technical Reports Server (NTRS)
Bogert, Philip B.; Satyanarayana, Arunkumar; Chunchu, Prasad B.
2006-01-01
Splitting, ultimate failure load and the damage path in center notched composite specimens subjected to in-plane tension loading are predicted using progressive failure analysis methodology. A 2-D Hashin-Rotem failure criterion is used in determining intra-laminar fiber and matrix failures. This progressive failure methodology has been implemented in the Abaqus/Explicit and Abaqus/Standard finite element codes through user written subroutines "VUMAT" and "USDFLD" respectively. A 2-D finite element model is used for predicting the intra-laminar damages. Analysis results obtained from the Abaqus/Explicit and Abaqus/Standard code show good agreement with experimental results. The importance of modeling delamination in progressive failure analysis methodology is recognized for future studies. The use of an explicit integration dynamics code for simple specimen geometry and static loading establishes a foundation for future analyses where complex loading and nonlinear dynamic interactions of damage and structure will necessitate it.
Evaluation of dispersivity coefficients by means of a laboratory image analysis
NASA Astrophysics Data System (ADS)
Citarella, Donato; Cupola, Fausto; Tanda, Maria Giovanna; Zanini, Andrea
2015-01-01
This paper describes the application of an innovative procedure that allows the estimation of longitudinal and transverse dispersivities in an experimental plume devised in a laboratory sandbox. The phenomenon of transport in porous media is studied using sodium fluorescein as tracer. The fluorescent excitation was achieved by using blue light and the concentration data were obtained through the processing of side wall images collected with a high resolution color digital camera. After a calibration process, the relationship between the luminosity of the emitted fluorescence and the fluorescein concentration was determined at each point of the sandbox. The relationships were used to describe the evolution of the transport process quantitatively throughout the entire domain. Some check tests were performed in order to verify the reliability of the experimental device. Numerical flow and transport models of the sandbox were developed and calibrated comparing computed and observed flow rates and breakthrough curves. The estimation of the dispersivity coefficients was carried out by analyzing the concentration field deduced from the images collected during the experiments; the dispersivity coefficients were evaluated in the domain zones where the tracer affected the porous medium under the hypothesis that the transport phenomenon is described by advection-dispersion equation (ADE) and by computing the differential components of the concentration by means of a numerical leap-frog scheme. The values determined agree with the ones referred in literature for similar media and with the coefficients obtained by calibrating the numerical model. Very interesting considerations have been made from the analysis of the performance of the methodology at different locations in the flow domain and phases of the plume evolution.
Laser-Induced Breakdown Spectroscopy in open-path configuration for the analysis of distant objects
NASA Astrophysics Data System (ADS)
Sallé, B.; Mauchien, P.; Maurice, S.
2007-08-01
A review of recent results on stand-off Laser-Induced Breakdown Spectroscopy (LIBS) analysis and applications is presented. Stand-off LIBS was suggested for elemental analysis of materials located in environments where any physical access was not possible but optical access could be envisaged. This review only refers to the use of the open-path LIBS configuration in which the laser beam and the returning plasma light are transmitted through the atmosphere. It does not present the results obtained with a transportation of the laser pulses to the target through an optical fiber. Open-path stand-off LIBS has mainly been used with nanosecond laser pulses for solid sample analysis at distances of tens of meters. Liquid samples have also been analyzed at distances of a few meters. The distances achievable depend on many parameters including the laser characteristics (pulse energy and power, beam divergence, spatial profile) and the optical system used to focus the pulses at a distance. A large variety of laser focusing systems have been employed for stand-off analysis comprising refracting or reflecting telescope. Efficient collection of the plasma light is also needed to obtain analytically useful signals. For stand-off LIBS analysis, a lens or a mirror is required to increase the solid angle over which the plasma light can be collected. The light collection device can be either at an angle from the laser beam path or collinear with the optical axis of the system used to focus the laser pulses on the target surface. These different configurations have been used depending on the application such as rapid sorting of metal samples, identification of material in nuclear industry, process control and monitoring in metallurgical industry, applications in future planetary missions, detection of environmental contamination or cleaning of objects of cultural heritage. Recent stand-off analyses of metal samples have been reported using femtosecond laser pulses to extend LIBS
NASA Astrophysics Data System (ADS)
van Lew, Baldur; Botha, Charl P.; Milles, Julien R.; Vrooman, Henri A.; van de Giessen, Martijn; Lelieveldt, Boudewijn P. F.
2015-03-01
The cohort size required in epidemiological imaging genetics studies often mandates the pooling of data from multiple hospitals. Patient data, however, is subject to strict privacy protection regimes, and physical data storage may be legally restricted to a hospital network. To enable biomarker discovery, fast data access and interactive data exploration must be combined with high-performance computing resources, while respecting privacy regulations. We present a system using fast and inherently secure light-paths to access distributed data, thereby obviating the need for a central data repository. A secure private cloud computing framework facilitates interactive, computationally intensive exploration of this geographically distributed, privacy sensitive data. As a proof of concept, MRI brain imaging data hosted at two remote sites were processed in response to a user command at a third site. The system was able to automatically start virtual machines, run a selected processing pipeline and write results to a user accessible database, while keeping data locally stored in the hospitals. Individual tasks took approximately 50% longer compared to a locally hosted blade server but the cloud infrastructure reduced the total elapsed time by a factor of 40 using 70 virtual machines in the cloud. We demonstrated that the combination light-path and private cloud is a viable means of building an analysis infrastructure for secure data analysis. The system requires further work in the areas of error handling, load balancing and secure support of multiple users.
The Land Gini Coefficient and Its Application for Land Use Structure Analysis in China
Zheng, Xinqi; Xia, Tian; Yang, Xin; Yuan, Tao; Hu, Yecui
2013-01-01
We introduce the Gini coefficient to assess the rationality of land use structure. The rapid transformation of land use in China provides a typical case for land use structure analysis. In this study, a land Gini coefficient (LGC) analysis tool was developed. The land use structure rationality was analyzed and evaluated based on statistical data for China between 1996 and 2008. The results show: (1)The LGC of three major land use types–farmland, built-up land and unused land–was smaller when the four economic districts were considered as assessment units instead of the provinces. Therefore, the LGC is spatially dependent; if the calculation unit expands, then the LGC decreases, and this relationship does not change with time. Additionally, land use activities in different provinces of a single district differed greatly. (2) At the national level, the LGC of the three main land use types indicated that during the 13 years analyzed, the farmland and unused land were evenly distributed across China. However, the built-up land distribution was relatively or absolutely unequal and highlights the rapid urbanization in China. (3) Trends in the distribution of the three major land use types are very different. At the national level, when using a district as the calculation unit, the LGC of the three main land use types increased, and their distribution became increasingly concentrated. However, when a province was used as the calculation unit, the LGC of the farmland increased, while the LGC of the built-up and unused land decreased. These findings indicate that the distribution of the farmland became increasingly concentrated, while the built-up land and unused land became increasingly uniform. (4) The LGC analysis method of land use structure based on geographic information systems (GIS) is flexible and convenient. PMID:24130764
Yu, Liyang; Han, Qi; Niu, Xiamu; Yiu, S M; Fang, Junbin; Zhang, Ye
2016-02-01
Most of the existing image modification detection methods which are based on DCT coefficient analysis model the distribution of DCT coefficients as a mixture of a modified and an unchanged component. To separate the two components, two parameters, which are the primary quantization step, Q1, and the portion of the modified region, α, have to be estimated, and more accurate estimations of α and Q1 lead to better detection and localization results. Existing methods estimate α and Q1 in a completely blind manner, without considering the characteristics of the mixture model and the constraints to which α should conform. In this paper, we propose a more effective scheme for estimating α and Q1, based on the observations that, the curves on the surface of the likelihood function corresponding to the mixture model is largely smooth, and α can take values only in a discrete set. We conduct extensive experiments to evaluate the proposed method, and the experimental results confirm the efficacy of our method. PMID:26804669
Hierarchy of Dysfunction Related to Dressing Performance in Stroke Patients: A Path Analysis Study
Fujita, Takaaki; Nagayama, Hirofumi; Sato, Atsushi; Yamamoto, Yuichi; Yamane, Kazuhiro; Otsuki, Koji; Tsuchiya, Kenji; Tozato, Fusae
2016-01-01
Previous reports indicated that various dysfunctions caused by stroke affect the level of independence in dressing. These dysfunctions can be hierarchical, and these effects on dressing performance can be complicated in stroke patients. However, there are no published reports focusing on the hierarchical structure of the relationships between the activities of daily living and balance function, motor and sensory functions of the affected lower limb, strength of the abdominal muscles and knee extension on the unaffected side, and visuospatial deficits. The purpose of this study was to elucidate the hierarchical and causal relationships between dressing performance and these dysfunctions in stroke patients. This retrospective study included 104 first-time stroke patients. The causal relationship between the dressing performance and age, time post stroke, balance function, motor and sensory functions of the affected lower limb, strength of the abdominal muscles and knee extension on the unaffected side, and visuospatial deficits were examined using path analysis. A hypothetical path model was created based on previous studies, and the goodness of fit between the data and model were verified. A modified path model was created that achieved an almost perfect fit to the data. Balance function and abdominal muscle strength have direct effects on dressing performance, with standardized direct effect estimates of 0.78 and 0.15, respectively. Age, motor and sensory functions of the affected lower limb, and strength of abdominal muscle and knee extension on the unaffected side have indirect effects on dressing by influencing balance function. Our results suggest that dressing performance depends strongly on balance function, and it is mainly influenced by the motor function of the affected lower limb. PMID:26954499
Converted-wave PS arrivals in tilted TI media: Analysis of ray-paths and amplitudes
NASA Astrophysics Data System (ADS)
Ramos-Martinez, J.; Calderon-Macias, C.
2005-05-01
Converted-waves, i.e., downgoing P-waves that convert upon reflection to S-waves, excited by a compressional source and recorded by horizontal geophones provide a measure of media properties that relate to rock type and fluid saturation. Other uses that have arisen from measuring, analyzing and interpreting PS-waves, include improved structural imaging in formations with occurrence of gas and analysis of seismic anisotropy for estimating fracture density and orientation. Addressing anisotropy in the seismic processing flow is paramount due to the strong influence of this phenomenon in the wave path. Furthermore, analyses of both traveltimes and amplitudes that include anisotropic parameters provide a better picture of the subsurface. Anisotropy types used to describe common geologic scenarios include vertical and horizontal transversely isotropy (VTI and HTI, respectively). Presence of horizontal shale formations is a common cause of the VTI type, while a single vertical fracture system is a typical example of the HTI. Another degree of complexity is to consider a tilted symmetry axis corresponding to a formation with thin layers that are dipping, or the presence of non-vertical fractures. These media, described as tilted TI, have important observable effects on the converted-wave arrivals: i) asymmetry of the wave-path; ii) shear-wave splitting; and iii) non-zero amplitudes at zero offset. Based on numerical modeling, effects of the tilt in the simmetry axis on arrival times, travel path, and amplitudes of the converted waves are analyzed. Ultimate objectives of the work include quantifying these effects on converted-wave data processing, and investigating the reflected wavefield signature for retrieving tilt angle in situations where the stress field induces thin layering or fractures with a tilted symmetry axis.
NASA Astrophysics Data System (ADS)
Mockler, Eva M.; O'Loughlin, Fiachra E.; Bruen, Michael
2016-05-01
Increasing pressures on water quality due to intensification of agriculture have raised demands for environmental modeling to accurately simulate the movement of diffuse (nonpoint) nutrients in catchments. As hydrological flows drive the movement and attenuation of nutrients, individual hydrological processes in models should be adequately represented for water quality simulations to be meaningful. In particular, the relative contribution of groundwater and surface runoff to rivers is of interest, as increasing nitrate concentrations are linked to higher groundwater discharges. These requirements for hydrological modeling of groundwater contribution to rivers initiated this assessment of internal flow path partitioning in conceptual hydrological models. In this study, a variance based sensitivity analysis method was used to investigate parameter sensitivities and flow partitioning of three conceptual hydrological models simulating 31 Irish catchments. We compared two established conceptual hydrological models (NAM and SMARG) and a new model (SMART), produced especially for water quality modeling. In addition to the criteria that assess streamflow simulations, a ratio of average groundwater contribution to total streamflow was calculated for all simulations over the 16 year study period. As observations time-series of groundwater contributions to streamflow are not available at catchment scale, the groundwater ratios were evaluated against average annual indices of base flow and deep groundwater flow for each catchment. The exploration of sensitivities of internal flow path partitioning was a specific focus to assist in evaluating model performances. Results highlight that model structure has a strong impact on simulated groundwater flow paths. Sensitivity to the internal pathways in the models are not reflected in the performance criteria results. This demonstrates that simulated groundwater contribution should be constrained by independent data to ensure results
Vereecken, H; Vanderborght, J; Kasteel, R; Spiteller, M; Schäffer, A; Close, M
2011-01-01
In this study, we analyzed sorption parameters for pesticides that were derived from batch and column or batch and field experiments. The batch experiments analyzed in this study were run with the same pesticide and soil as in the column and field experiments. We analyzed the relationship between the pore water velocity of the column and field experiments, solute residence times, and sorption parameters, such as the organic carbon normalized distribution coefficient ( ) and the mass exchange coefficient in kinetic models, as well as the predictability of sorption parameters from basic soil properties. The batch/column analysis included 38 studies with a total of 139 observations. The batch/field analysis included five studies, resulting in a dataset of 24 observations. For the batch/column data, power law relationships between pore water velocity, residence time, and sorption constants were derived. The unexplained variability in these equations was reduced, taking into account the saturation status and the packing status (disturbed-undisturbed) of the soil sample. A new regression equation was derived that allows estimating the values derived from column experiments using organic matter and bulk density with an value of 0.56. Regression analysis of the batch/column data showed that the relationship between batch- and column-derived values depends on the saturation status and packing of the soil column. Analysis of the batch/field data showed that as the batch-derived value becomes larger, field-derived values tend to be lower than the corresponding batch-derived values, and vice versa. The present dataset also showed that the variability in the ratio of batch- to column-derived value increases with increasing pore water velocity, with a maximum value approaching 3.5. PMID:21546674
Gaussian white noise analysis and its application to Feynman path integral
NASA Astrophysics Data System (ADS)
Suryawan, Herry Pribawanto
2016-02-01
In applied science, Gaussian white noise (the time derivative of Brownian motion) is often chosen as a mathematical idealization of phenomena involving sudden and extremely large fluctuations. It is also possible to define and study Gaussian white noise in a mathematically rigorous framework. In this survey paper we review the Gaussian white noise as an object in an infinite dimensional topological vector space. A brief construction of Gaussian white noise space and Gaussian white noise distributions will be presented. Gaussian white noise analysis provides a framework which offers various generalization of concept known from finite dimensional analysis to the infinite dimensional case, among them are differential operators, Fourier transform, and distribution theory. We will also present some recent developments and results on the application of Gaussian white noise theory to Feynman's path integral approach for quantum mechanics.
NASA Astrophysics Data System (ADS)
Cao, Guangxi; He, Cuiting; Xu, Wei
2016-03-01
This study investigates the correlation between weather and agricultural futures markets on the basis of detrended cross-correlation analysis (DCCA) cross-correlation coefficients and q-dependent cross-correlation coefficients. In addition, detrended fluctuation analysis (DFA) is used to measure extreme weather and thus analyze further the effect of this condition on agricultural futures markets. Cross-correlation exists between weather and agricultural futures markets on certain time scales. There are some correlations between temperature and soybean return associated with medium amplitudes. Under extreme weather conditions, weather exerts different influences on different agricultural products; for instance, soybean return is greatly influenced by temperature, and weather variables exhibit no effect on corn return. Based on the detrending moving-average cross-correlation analysis (DMCA) coefficient and DFA regression results are similar to that of DCCA coefficient.
NASA Astrophysics Data System (ADS)
Kikuchi, Yuta; Tsumura, Kyosuke; Kunihiro, Teiji
2016-05-01
We give a quantitative analysis of the dynamical properties of fermionic cold atomic gases in normal phase, such as the shear viscosity, heat conductivity, and viscous relaxation times, using the novel microscopic expressions derived by the renormalization group (RG) method, where the Boltzmann equation is faithfully solved to extract the hydrodynamics without recourse to any ansatz. In particular, we examine the quantum statistical effects, temperature dependence, and scattering-length dependence of the transport coefficients and the viscous relaxation times. The numerical calculation shows that the relation τπ = η / P, which is derived in the relaxation-time approximation (RTA) and is used in most of the literature, turns out to be satisfied quite well, while the similar relation for the viscous relaxation time τJ of the heat conductivity is satisfied only approximately with a considerable error.
Analysis of rotordynamic coefficients of helically-grooved turbulent annular seals
NASA Technical Reports Server (NTRS)
Kim, C.-H.; Childs, D. W.
1986-01-01
An analysis for helically-grooved turbulent annular seals is developed to predict leakage and dynamic coefficients, as related to rotordynamics. The grooved surface pattern is formulated as an inhomogeneous directivity in surface shear stress. The zeroth-order equations define the steady-state leakage and the circumferential velocity development due to wall shear for a centered rotor position. The first-order equations define perturbations in the pressure and axial and circumferential velocity fields due to small motion of the rotor about the centered position. Numerical results are presented for proposed grooved seals in the High Pressure Oxygen Turbopump (HPTOP) of the Space Shuttle Main Engine (SSME) and for a water-pump application. The results show that an optimum helix angle exists from a rotordynamic stability viewpoint. Further, a properly designed helically-grooved stator is predicted to have pronounced stability advantages over other currently used seals.
Kramers-Moyal coefficients in the analysis and modeling of heart rate variability
NASA Astrophysics Data System (ADS)
Petelczyc, M.; Żebrowski, J. J.; Baranowski, R.
2009-09-01
Modeling of recorded time series may be used as a method of analysis for heart rate variability studies. In particular, the extraction of the first two Kramers-Moyal coefficients has been used in this context. Recently, the method was applied to a wide range of signal analysis: from financial data to physiological and biological time series. Modeling of the signal is important for the prediction and interpretation of the dynamics underlying the process. The method requires the determination of the Markov time. Obtaining the drift and diffusion term of the Kramers-Moyal expansion is crucial for the modeling of the original time series with the Langevin equation. Both Tabar [Comput. Sci. Eng. 8, 54 (2006)] and T. Kuusela [Phys. Rev. E 69, 031916 (2004)] suggested that these terms may be used to distinguish healthy subjects from those with heart failure. The research groups applied a somewhat different methodology and obtained substantially different ranges of the Markov time. We show that the two studies may be considered consistent with each other as Kuusela analyzed 24 h recordings while Tabar analyzed daytime and nighttime recordings, separately. However, both groups suggested using the Langevin equation for modeling of time series which requires the fluctuation force to be a Gaussian. We analyzed heart rate variability recordings for ten young male (age 26-4+3y ) healthy subjects. 24 h recordings were analyzed and 6-h-long daytime and nighttime fragments were selected. Similar properties of the data were observed in all recordings but all the nighttime data and seven of the ten 24 h series exhibited higher-order, non-negligible Kramers-Moyal coefficients. In such a case, the reconstruction of the time series using the Langevin equation is impossible. The non-negligible higher-order coefficients are due to autocorrelation in the data. This effect may be interpreted as a result of a physiological phenomenon (especially occurring for nighttime data): respiratory
NASA Astrophysics Data System (ADS)
Scholtes, Ingo; Wider, Nicolas; Garas, Antonios
2016-03-01
Despite recent advances in the study of temporal networks, the analysis of time-stamped network data is still a fundamental challenge. In particular, recent studies have shown that correlations in the ordering of links crucially alter causal topologies of temporal networks, thus invalidating analyses based on static, time-aggregated representations of time-stamped data. These findings not only highlight an important dimension of complexity in temporal networks, but also call for new network-analytic methods suitable to analyze complex systems with time-varying topologies. Addressing this open challenge, here we introduce a novel framework for the study of path-based centralities in temporal networks. Studying betweenness, closeness and reach centrality, we first show than an application of these measures to time-aggregated, static representations of temporal networks yields misleading results about the actual importance of nodes. To overcome this problem, we define path-based centralities in higher-order aggregate networks, a recently proposed generalization of the commonly used static representation of time-stamped data. Using data on six empirical temporal networks, we show that the resulting higher-order measures better capture the true, temporal centralities of nodes. Our results demonstrate that higher-order aggregate networks constitute a powerful abstraction, with broad perspectives for the design of new, computationally efficient data mining techniques for time-stamped relational data.
A Path Analysis of Mental Health Among Thai Immigrant Employees in Pranakron Si Ayutthaya Province.
Kaewanuchit, Chonticha; Sawangdee, Yothin
2016-08-01
The aims of this research were to study both direct and indirect path analyses of mental health, and to analyse a causal relationship of each variable. A cross-sectional study used stratified random sampling to select Thai immigrant employees in Pranakron Si Ayutthaya Province, Thailand. General data were analysed by number and percentage. The mental health variable was measured by THMHI-15. The latter was analysed by general statistic, and a path analysis. The results found that job conditions and distance travelled between house and workplace had a direct effect on mental health with a standardised regression weight of 0.581, and -0.443, respectively (p value <0.01). It was found that housing conditions had no effect on mental health. The income variable had a direct influence on mental health with a standardised regression weight of 0.68 (p value <0.01). This research indicated that job conditions were an important factor related to mental health. PMID:26289500
Elastic coefficient of a single polymer chain by using Brownian dynamics analysis
NASA Astrophysics Data System (ADS)
Horinaka, J.; Maniwa, T.; Oharada, K.; Takigawa, T.
2007-08-01
The elastic coefficient of a single polystyrene chain has been experimentally evaluated by using Brownian dynamics analysis. The Brownian motion of the chain is probed using a particle trapped by optical tweezers with a negligibly small spring constant. The displacement of the particle due to Brownian motion is measured by an interferometer assembled using the same laser beam as the optical tweezers. Two methods are employed for Brownian dynamics analysis: (1) the analysis of the time course of the displacement of the particle and (2) the fitting of the power spectrum of Brownian motion with a Lorentzian. The elastic constant of a polystyrene chain in dichloromethane at 21 °C is estimated to be 6.4×10-6 and 1.1×10-5 N/m when methods (1) and (2) are employed, respectively. The elastic constant obtained by approximating the polystyrene chain to a freely jointed chain is in agreement with the experimentally evaluated elastic constant.
Analysis and Monte Carlo simulation of near-terminal aircraft flight paths
NASA Technical Reports Server (NTRS)
Schiess, J. R.; Matthews, C. G.
1982-01-01
The flight paths of arriving and departing aircraft at an airport are stochastically represented. Radar data of the aircraft movements are used to decompose the flight paths into linear and curvilinear segments. Variables which describe the segments are derived, and the best fitting probability distributions of the variables, based on a sample of flight paths, are found. Conversely, given information on the probability distribution of the variables, generation of a random sample of flight paths in a Monte Carlo simulation is discussed. Actual flight paths at Dulles International Airport are analyzed and simulated.
A stochastic analysis of terrain evaluation variables for path selection. [roving vehicle navigation
NASA Technical Reports Server (NTRS)
Donohue, J. G.; Shen, C. N.
1978-01-01
A stochastic analysis was performed on the variables associated with the characteristics of the terrain encountered by a roving system with an autonomous navigation system. A laser rangefinder is employed to detect terrain features at ranges up to 75 m. Analytic expressions and a numerical scheme were developed to calculate the variance of data on these four variables: (1) body clearance, (2) in-path slope, (3) tilt slope, and (4) wheel deviation. The variance is due to noise in the range data. It was found that the standard deviation of these terrain variables is large enough to warrant the use of a safety margin to aid the roving vehicle in avoiding high risk areas.
Freight Network Modeling System. Volume IV. Shortest-Path Analysis and Display user's guide
Not Available
1985-04-01
The Freight Network Modeling System (FNEM) is a general and flexible modeling system designed to have wide applicability to a variety of freight transportation analyses. The system consists of compatible network data bases, data management software, models of freight transportation, report generators, and graphics output. In many studies, a model as comprehensive as FNEM is not required. The second model, Shortest-Path Analysis and Display (SPAD), is a simpler model that optimizes routings of single shipments. The routing criteria that can be used are numerous - including minimizing cost, minimizing delay, minimizing population exposure (useful when considering shipments of hazardous materials), and minimizing accident risk. In addition to the above criteria, the routes can also be restricted to those with clearance for oversized loads or with sufficient load capabilities. SPAD can be used interactively and the routes can be displayed graphically. This volume contains a user's guide for SPAD including preprocessor programs and SPAD execution. 7 figs., 19 tabs.
Connection Availability Analysis of Shared Backup Path-Protected Mesh Networks
NASA Astrophysics Data System (ADS)
Zhou, Ling; Held, Marcel; Sennhauser, Urs
2007-05-01
Dual-span failures dominate the system unavailability in a mesh-restorable network with full restorability to single-span failures. Traditional availability analysis based on reliability block diagrams is not suitable for survivable networks with shared spare capacity. Therefore, a new concept is proposed to facilitate the calculations of connection availability. A U.S. network consisting of 19 nodes and 28 spans yielding 171 bidirectional connections is investigated. We find that networks with shared backup path protection can have average connection unavailabilities of the same order of magnitude as those with dedicated automatic protection switching, however, with a much better capacity efficiency. The proposed method can exactly calculate the unavailability of a specific connection with known restoration details or the average connection performance without any restoration details by presuming the dual-span failures to be the only failure mode and an arbitrary allocation rule of spare capacity.
A path analysis of reading comprehension for adults with low literacy
Mellard, Daryl F.; Fall, Emily; Woods, Kari L.
2010-01-01
Adult literacy interventions often rely on models of reading validated with children or adult populations with a broad range of reading. Such models do not fully satisfy the need for intervention research and development for adults with low literacy. Thus, the authors hypothesized that a model representing the relationship between reading component skills would be predictive of reading comprehension for an adult population with low literacy and beneficial to adult literacy researchers. Using data from 174 adults participating in adult basic education and secondary education programs, the authors performed a path analysis of component skills' contribution to reading comprehension. The findings are clear that existing reading models do not describe this population. The implications are discussed in terms of instructional and curricular interventions. PMID:20179309
Lockie, Stewart; Lyons, Kristen; Lawrence, Geoffrey; Grice, Janet
2004-10-01
Path analysis of attitudinal, motivational, demographic and behavioural factors influencing food choice among Australian consumers who had consumed at least some organic food in the preceding 12 months showed that concern with the naturalness of food and the sensory and emotional experience of eating were the major determinants of increasing levels of organic consumption. Increasing consumption was also related to other 'green consumption' behaviours such as recycling and to lower levels of concern with convenience in the purchase and preparation of food. Most of these factors were, in turn, strongly affected by gender and the level of responsibility taken by respondents for food provisioning within their households, a responsibility dominated by women. Education had a slightly negative effect on the levels of concern for sensory and emotional appeal due to lower levels of education among women. Income, age, political and ecological values and willingness to pay a premium for safe and environmentally friendly foods all had extremely minor effects. PMID:15458800
Visualization and analysis of occlusion for human jaws using a "functionally generated path"
NASA Astrophysics Data System (ADS)
Myszkowski, Karol; Herder, Jens; Kunii, Tosiyasu L.; Ibusuki, Masumi
1996-03-01
Dynamic characteristics of occlusion during lower jaw motion are useful in the diagnosis of jaw articulation problems and in computer-aided design/ manufacture of teeth restorations. The Functionally Generated Path (FGP), produced as a surface which envelops the actual occlusal surface of the moving opponent jaw, can be used for compact representation of dynamic occlusal relations. In traditional dentistry FGP is recorded as a bite impression in a patient's mouth. We propose an efficient computerized technique for FGP reconstruction and validate it through implementation and testing. The distance maps between occlusal surfaces of jaws, calculated for multiple projection directions and accumulated for mandibular motion, provide information for FGP computation. Rasterizing graphics hardware is used for fast calculation of the distance maps. Real-world data are used: the scanned shape of teeth and the measured motion of the lower jaw. We show applications of FGP to analysis of the occlusion relations and occlusal surface design for restorations.
NASA Astrophysics Data System (ADS)
Johnson, James; Conley, Catharine; Siegel, Bette
As systems, technologies, and plans for the human exploration of Mars and other destinations beyond low Earth orbit begin to coalesce, it is imperative that frequent and early consideration is given to how planetary protection practices and policy will be upheld. While the development of formal planetary protection requirements for future human space systems and operations may still be a few years from fruition, guidance to appropriately influence mission and system design will be needed soon to avoid costly design and operational changes. The path to constructing such requirements is a journey that espouses key systems engineering practices of understanding shared goals, objectives and concerns, identifying key stakeholders, and iterating a draft requirement set to gain community consensus. This paper traces through each of these practices, beginning with a literary analysis of nearly three decades of publications addressing planetary protection concerns with respect to human exploration. Key goals, objectives and concerns, particularly with respect to notional requirements, required studies and research, and technology development needs have been compiled and categorized to provide a current ‘state of knowledge’. This information, combined with the identification of key stakeholders in upholding planetary protection concerns for human missions, has yielded a draft requirement set that might feed future iteration among space system designers, exploration scientists, and the mission operations community. Combining the information collected with a proposed forward path will hopefully yield a mutually agreeable set of timely, verifiable, and practical requirements for human space exploration that will uphold international commitment to planetary protection. Keywords: planetary protection, human spaceflight requirements, human space exploration, human space operations, systems engineering, literature analysis
Intimate partner violence in the eastern part of Iran: a path analysis of risk factors.
Moghaddam Hosseini, Vahideh; Asadi, Zahra Sadat; Akaberi, Arash; Hashemian, Masoumeh
2013-08-01
Intimate partner violence against women is a widespread phenomenon that is the cause of many deleterious health and social consequences. This study examines the impact of some risk factors on partner violence in the eastern region of Iran, using path analysis. The study used a population-based cross sectional study design. In this study, 251 married women who were referred to the health centers were selected through a proportionally stratified and randomized sampling method. Domestic violence was measured using Conflict Tactics Scale and the socio-demographic variable was assessed by a self-report questionnaire. Bayesian Structural Equation Modeling was used for evaluating the overall path analysis and the direct and indirect p-value was estimated by Bootstrap method. AMOS and SPSS software were used to analyze data. The prevalence of overall violence was 78.1%, with 37.8% and 0.8% of women reporting minor and severe violence, respectively, and 39.8% reporting both severe and minor forms of violence. Psychological violence was the most common type of violence reported (66.5%). The model showed that husbands' drug abuse and women's higher level of education compared to their husbands were the first and second most important factors that significantly and directly influenced the violence. The women's attitude, however, had the least effect on the violence. The findings indicated that higher educated women and women with addicted husbands were more likely to experience violence. Treating the drug abuse disorders, especially mental disorders, using behavioral couple's therapy, as well as modifying certain traditional and cultural biases against women's empowerment are suggested. PMID:23909674
Measurements and analysis of electron transport coefficients obtained by a pulsed Townsend technique
NASA Astrophysics Data System (ADS)
Šašić, O.; de Urquijo, J.; Juárez, A. M.; Dupljanin, S.; Jovanović, J.; Hernández-Ávila, J. L.; Basurto, E.; Petrović, Z. Lj
2010-06-01
A review of a wide range of electron swarm studies in several pure gases and gas mixtures is given. These studies include the determination of the cross section set for electrons in C2H2F2 (R134a) based on recent measurements of transport data, the re-analysis of the cross sections for electrons in N2O and its mixtures with N2 and SF6 and, finally, the analysis of electron transport in N2-Ar and Xe-He mixtures. It was found that in the case of R134a further studies of the characteristic energy are needed for its mixtures with argon in pure gases in order to obtain a reliable set of cross sections. For N2O, a set has been developed that fits a wide range of data. However, some verification of significant changes in the shape of the attachment cross section should still be done. In two different sets of data for the mixtures of Xe and He and of Ar and N2, the existing cross sections do a very good job throughout most of the energy range, although some small adjustments may be sought at the higher end of the relevant energy range for xenon. In this paper we summarize the work already described in separate papers for each of the He-Xe and Ar-N2 mixtures, and we present here a number of transport coefficients and analyses that were not included in the original papers.
NASA Technical Reports Server (NTRS)
Childs, D. W.
1983-01-01
An improved theory for the prediction of the rotordynamic coefficients of turbulent annular seals was developed. Predictions from the theory are compared to the experimental results and an approach for the direct calculation of empirical turbulent coefficients from test data are introduced. An improved short seal solution is shown to do a better job of calculating effective stiffness and damping coefficients than either the original short seal solution or a finite length solution. However, the original short seal solution does a much better job of predicting equivalent added mass coefficient.
[Optical Path Difference Analysis and Simulation of Four Typical Rotary Type Interferometer].
Feng, Ming-chun; Liu, Wen-qing; Xu, Liang; Gao, Min-guang; Wei, Xiu-li; Tong, Jing-jing; Li, Xiang-xian
2015-11-01
The four kinds of the structure characteristics of rotary type interferometer are mainly analyzed from the classical Michelson interferometer structure in the paper. The Optical path difference between the interferometer and the rotation angle is also analyzed. By setting parameters, the four kinds of rotary type optical path difference of the interferometer are simulated based on the optical path difference formula. The rotation velcocity of the four kinds of interferometers is also simulated. By simulation and contrast of the optical path difference, the relationship is intuitively reflect by figure between the optical path difference and the rotation angle. The scope of the rotation angle is discussed within 3% of the velocity errors. It is the very good reference significance to study the structure and properties of the interferometer by analyzing and simulating the optical path difference discussed in the paper. PMID:26978939
Sterner, Teresa R; Goodyear, Charles D; Robinson, Peter J; Mattie, David R; Burton, G Allen
2006-08-01
Algorithms predicting tissue and blood partition coefficients (PCs) from solvent properties were compared to assess their usefulness in a petroleum mixture physiologically based pharmacokinetic/pharmacodynamic model. Measured blood:air and tissue:blood PCs for rat and human tissues were sought from literature resources for 14 prevalent jet fuel (JP-8) components. Average experimental PCs were compared with predicted PCs calculated using algorithms from 9 published sources. Algorithms chosen used solvent PCs (octanol:water, saline or water:air, oil:air coefficients) due to the relative accessibility of these parameters. Tissue:blood PCs were calculated from ratios of predicted tissue:air and experimental blood:air values (PCEB). Of the 231 calculated values, 27% performed within +/- 20% of the experimental PC values. Physiologically based equations (based on water and lipid components of a tissue type) did not perform as well as empirical equations (derived from linear regression of experimental PC data) and hybrid equations (physiological parameters and empirical factors combined) for the jet fuel components. The major limitation encountered in this analysis was the lack of experimental data for the selected JP-8 constituents. PCEB values were compared with tissue:blood PCs calculated from ratios of predicted tissue:air and predicted blood:air values (PCPB). Overall, 68% of PCEB values had smaller absolute % errors than PCPB values. If calculated PC values must be used in models, a comparison of experimental and predicted PCs for chemically similar compounds would estimate the expected error level in calculated values. PMID:16766479
Leak-Path Factor Analysis for the Nuclear Materials Storage Facility
Shaffer, C.; Leonard, M.
1999-06-13
Leak-path factors (LPFs) were calculated for the Nuclear Materials Storage Facility (NMSF) located in the Plutonium Facility, Building 41 at the Los Alamos National Laboratory Technical Area 55. In the unlikely event of an accidental fire powerful enough to fail a container holding actinides, the subsequent release of oxides, modeled as PuO{sub 2} aerosols, from the facility and into the surrounding environment was predicted. A 1-h nondestructive assay (NDA) laboratory fire accident was simulated with the MELCOR severe accident analysis code. Fire-driven air movement along with wind-driven air infiltration transported a portion of these actinides from the building. This fraction is referred to as the leak-path factor. The potential effect of smoke aerosol on the transport of the actinides was investigated to verify the validity of neglecting the smoke as conservative. The input model for the NMSF consisted of a system of control volumes, flow pathways, and surfaces sufficient to model the thermal-hydraulic conditions within the facility and the aerosol transport data necessary to simulate the transport of PuO{sub 2} particles. The thermal-hydraulic, heat-transfer, and aerosol-transport models are solved simultaneously with data being exchanged between models. A MELCOR input model was designed such that it would reproduce the salient features of the fire per the corresponding CFAST calculation. Air infiltration into and out of the facility would be affected strongly by wind-driven differential pressures across the building. Therefore, differential pressures were applied to each side of the building according to guidance found in the ASHRAE handbook using a standard-velocity head equation with a leading multiplier to account for the orientation of the wind with the building. The model for the transport of aerosols considered all applicable transport processes, but the deposition within the building clearly was dominated by gravitational settling.
Worry, worry attacks, and PTSD among Cambodian refugees: a path analysis investigation.
Hinton, Devon E; Nickerson, Angela; Bryant, Richard A
2011-06-01
Among traumatized Cambodian refugees, this article investigates worry (e.g., the types of current life concerns) and how worry worsens posttraumatic stress disorder (PTSD). To explore how worry worsens PTSD, we examine a path model of worry to see whether certain key variables (e.g., worry-induced somatic arousal and worry-induced trauma recall) mediate the relationship between worry and PTSD. Survey data were collected from March 2010 until May 2010 in a convenience sample of 201 adult Cambodian refugees attending a psychiatric clinic in Massachusetts, USA. We found that worry was common in this group (65%), that worry was often about current life concerns (e.g., lacking financial resources, children not attending school, health concerns, concerns about relatives in Cambodia), and that worry often induced panic attacks: in the entire sample, 41% (83/201) of the patients had "worry attacks" (i.e., worry episodes that resulted in a panic episode) in the last month. "Worry attacks" were highly associated with PTSD presence. In the entire sample, generalized anxiety disorder was also very prevalent, and was also highly associated with PTSD. Path analysis revealed that the effect of worry on PTSD severity was mediated by worry-induced somatic arousal, worry-induced catastrophic cognitions, worry-induced trauma recall, inability to stop worry, and irritability. The final model accounted for 75% of the variance in PTSD severity among patients with worry. The public health and treatment implications of the study's findings that worry may have a potent impact on PTSD severity in severely traumatized populations are discussed: worry and daily concerns are key areas of intervention for these worry-hypersensitive (and hence daily-stressor-hypersensitive) populations. PMID:21663803
Antaki, G.A.
1991-01-01
ASME Code case N-468 recognizes the use of static analysis (the Load Coefficient Method or LCM) as an alternative to the commonly used response spectra modal analysis method (or RSMAM) for the structural evaluation of piping systems. The LCM, in various forms, has been commonly used in the late 1960's to mid-1970's for the design of nuclear piping systems of all sizes. With the advent of more user-friendly software, the LCM slowly gave way to the RSMAM, the latter being almost exclusively used throughout the 1980's. The paper presents the development of the seismic load coefficients in accordance with ASME Section III Code Case N-468. The load coefficients are then applied to 87 piping systems and compared to the response spectra modal analysis method.
Antaki, G.A.
1991-12-31
ASME Code case N-468 recognizes the use of static analysis (the Load Coefficient Method or LCM) as an alternative to the commonly used response spectra modal analysis method (or RSMAM) for the structural evaluation of piping systems. The LCM, in various forms, has been commonly used in the late 1960`s to mid-1970`s for the design of nuclear piping systems of all sizes. With the advent of more user-friendly software, the LCM slowly gave way to the RSMAM, the latter being almost exclusively used throughout the 1980`s. The paper presents the development of the seismic load coefficients in accordance with ASME Section III Code Case N-468. The load coefficients are then applied to 87 piping systems and compared to the response spectra modal analysis method.
Demetrashvili, Nino; Van den Heuvel, Edwin R
2015-06-01
This work is motivated by a meta-analysis case study on antipsychotic medications. The Michaelis-Menten curve is employed to model the nonlinear relationship between the dose and D2 receptor occupancy across multiple studies. An intraclass correlation coefficient (ICC) is used to quantify the heterogeneity across studies. To interpret the size of heterogeneity, an accurate estimate of ICC and its confidence interval is required. The goal is to apply a recently proposed generic beta-approach for construction the confidence intervals on ICCs for linear mixed effects models to nonlinear mixed effects models using four estimation methods. These estimation methods are the maximum likelihood, second-order generalized estimating equations and two two-step procedures. The beta-approach is compared with a large sample normal approximation (delta method) and bootstrapping. The confidence intervals based on the delta method and the nonparametric percentile bootstrap with various resampling strategies failed in our settings. The beta-approach demonstrates good coverages with both two-step estimation methods and consequently, it is recommended for the computation of confidence interval for ICCs in nonlinear mixed effects models for small studies. PMID:25703393
Satomura, Hironori; Adachi, Kohei
2013-07-01
To facilitate the interpretation of canonical correlation analysis (CCA) solutions, procedures have been proposed in which CCA solutions are orthogonally rotated to a simple structure. In this paper, we consider oblique rotation for CCA to provide solutions that are much easier to interpret, though only orthogonal rotation is allowed in the existing formulations of CCA. Our task is thus to reformulate CCA so that its solutions have the freedom of oblique rotation. Such a task can be achieved using Yanai's (Jpn. J. Behaviormetrics 1:46-54, 1974; J. Jpn. Stat. Soc. 11:43-53, 1981) generalized coefficient of determination for the objective function to be maximized in CCA. The resulting solutions are proved to include the existing orthogonal ones as special cases and to be rotated obliquely without affecting the objective function value, where ten Berge's (Psychometrika 48:519-523, 1983) theorems on suborthonormal matrices are used. A real data example demonstrates that the proposed oblique rotation can provide simple, easily interpreted CCA solutions. PMID:25106398
2014-01-07
PathFinder is a graph search program, traversing a directed cyclic graph to find pathways between labeled nodes. Searches for paths through ordered sequences of labels are termed signatures. Determining the presence of signatures within one or more graphs is the primary function of Path Finder. Path Finder can work in either batch mode or interactively with an analyst. Results are limited to Path Finder whether or not a given signature is present in the graph(s).
Katirag, Ahmet; Beker-Acay, Mehtap; Unlu, Ebru; Demirbas, Hayri; Demirturk, Nese
2016-01-01
Objective: Our purpose was to reveal the efficiency of diffusion weighted imaging (DWI) in the diagnosis of encephalitis, and to determine the relation between the apparent diffusion coefficient (ADC) values, the onset of the clinical symptoms, and the lesion extent. Methods: Conventional magnetic resonance imaging (MRI) was performed in 17 patients with encephalitis diagnosed on the basis of laboratory, clinical and radiologic findings during 2009 and 2015. Based on the duration between the onset of the symptoms and the brain MRI findings, the patients were divided into three groups. ADC values of the encephalitis lesion, the lesions’ topographic analysis score, deep gray matter involvement, patients’ clinical situation and the duration of the arrival to the clinic was examined. Results: Mean ADC values were 0,988±0,335 x10-3 mm2/s in group I (0-2 days), 1,045±0,347 x10-3 mm2/s in Group-II (3-7 days), 1,451±0,225 x10-3 mm2/s in Group-III (8 days and over). The relation between the ADC values and the duration of the arrival, topographic analysis score, the relation between the patients’ clinical situation and the deep gray matter involvement were found to be statistically significant. The deep gray matter involvement was demonstrated more clearly by FLAIR images when compared with DWI. Conclusion: Conventional MRI sequences may be insufficient in showing the encephalitis lesion. DWI must be added to the imaging modalities immediately in the cases suspected of having encephalitis. PMID:27375722
Muir, B. R.
2015-04-15
ADCL conformance with National Institute of Standards and Technology standards. This study shows that N{sub D,w} coefficients measured at different ADCLs are statistically equivalent, especially considering reasonable uncertainties. This analysis of N{sub D,w} coefficients also allows identification of chamber types that can be considered stable enough for accurate reference dosimetry.
Hessler, J.P.; Ogren, P.J.
1992-08-31
A technique was developed for determining relative importance and correlation between reactions making up a complex kinetic system. This technique was used to investigate measurements of optical absorption cross sections and the correlation between cross sections and measured rate coefficients. It is concluded that (1) species, initial conditions, and temporal regions may be identified where cross sections may be measured without interference from the kinetic behavior of the observed species and (2) experiments designed to measure rate coefficients will always be correlated with the absorption cross section of the observed species. This correlation may reduce the accuracy of rate coefficient measurements.
NASA Technical Reports Server (NTRS)
Brooks, Cuyler W., Jr.; Harris, Charles D.; Harvey, William D.
1991-01-01
A swept supercritical wing incorporating laminar flow control at transonic flow conditions was designed and tested. The definition of an experimental suction coefficient and a derivation of the compressible and incompressible formulas for the computation of the coefficient from measurable quantities is presented. The suction flow coefficient in the highest velocity nozzles is shown to be overpredicted by as much as 12 percent through the use of an incompressible formula. However, the overprediction on the computed value of suction drag when some of the suction nozzles were operating in the compressible flow regime is evaluated and found to be at most 6 percent at design conditions.
On load paths and load bearing topology from finite element analysis
NASA Astrophysics Data System (ADS)
Kelly, D.; Reidsema, C.; Lee, M.
2010-06-01
Load paths can be mapped from vector plots of 'pointing stress vectors'. They define a path along which a component of load remains constant as it traverses the solution domain. In this paper the theory for the paths is first defined. Properties of the plots that enable a designer to interpret the structural behavior from the contours are then identified. Because stress is a second order tensor defined on an orthogonal set of axes, the vector plots define separate paths for load transfer in each direction of the set of axes. An algorithm is therefore presented that combines the vectors to define a topology to carry the loads. The algorithm is shown to straighten the paths reducing bending moments and removing stress concentration. Application to a bolted joint, a racing car body and a yacht hull demonstrate the usefulness of the plots.
Definition and analysis of the lineshape matching coefficient in diode-pumped alkali vapor lasers
NASA Astrophysics Data System (ADS)
Shen, Binglin; Pan, Bailiang; Yang, Jing; Qian, Aiqing; Jiao, Jian
2014-12-01
For diode-pumped alkali lasers (DPALs), the matching of lineshape between D2 absorption line and pump light greatly affects the properties of laser output; however, there is rare theoretical study on the quantitative description of the lineshape matching coefficient. In this paper, we put forward a formula to describe the lineshape matching coefficient that represents the matching degree between D2 absorption line and pump light. Dependences of the matching coefficient and optical-optical efficiency on the linewidth ratio between D2 absorption line and pump light, and the center frequency shift of pump light caused by mode hopping are calculated and compared with experimental results in literatures. Results show the definition of lineshape matching coefficient can provide an effective way to improve the pump efficiency of DPALs.
ERIC Educational Resources Information Center
Tonyan, Holli A.; Nuttall, Joce
2014-01-01
Family day care or childminding involves a particularly transient workforce. This paper introduces Eco(logical)-Cultural Theory (ECT) to examine the cultural organisation of childminding and presents an ECT analysis of pilot survey results: asking minders about their daily routines and their career paths. Reasons for becoming a minder and…
ERIC Educational Resources Information Center
Middleton, James A.; Leavy, Aisling; Leader, Lars
2013-01-01
This study investigated the relationship among critical motivational variables and mathematics achievement as middle grades students engaged in a reform-oriented curriculum, "Mathematics in Context." We tested 327 students in fifth, sixth, and seventh grade before and after two years of implementation. We performed a path analysis with…
NASA Astrophysics Data System (ADS)
Yu, Shao-De; Wu, Shi-Bin; Wang, Hao-Yu; Wei, Xin-Hua; Chen, Xin; Pan, Wan-Long; Hu, Jiani; Xie, Yao-Qin
2015-12-01
Similarity coefficient mapping (SCM) aims to improve the morphological evaluation of weighted magnetic resonance imaging However, how to interpret the generated SCM map is still pending. Moreover, is it probable to extract tissue dissimilarity messages based on the theory behind SCM? The primary purpose of this paper is to address these two questions. First, the theory of SCM was interpreted from the perspective of linear fitting. Then, a term was embedded for tissue dissimilarity information. Finally, our method was validated with sixteen human brain image series from multi-echo . Generated maps were investigated from signal-to-noise ratio (SNR) and perceived visual quality, and then interpreted from intra- and inter-tissue intensity. Experimental results show that both perceptibility of anatomical structures and tissue contrast are improved. More importantly, tissue similarity or dissimilarity can be quantified and cross-validated from pixel intensity analysis. This method benefits image enhancement, tissue classification, malformation detection and morphological evaluation. Project supported in part by the National High Technology Research and Development Program of China (Grant Nos. 2015AA043203 and 2012AA02A604), the National Natural Science Foundation of China (Grant Nos. 81171402, 61471349, and 81501463), the Innovative Research Team Program of Guangdong Province, China (Grant No. 2011S013), the Science and Technological Program for Higher Education, Science and Research, and Health Care Institutions of Guangdong Province, China (Grant No. 2011108101001), the Natural Science Foundation of Guangdong Province, China (Grant No. 2014A030310360), the Fundamental Research Program of Shenzhen City, China (Grant No. JCYJ20140417113430639), and Beijing Center for Mathematics and Information Interdisciplinary Sciences, China.
Dogra, Debi Prosad; Badri, Vishal; Majumdar, Arun Kumar; Sural, Shamik; Mukherjee, Jayanta; Mukherjee, Suchandra; Singh, Arun
2014-09-01
Video object tracking plays an important role in many computer vision-aided applications. This paper presents a novel multi-path analysis-based video object tracking algorithm. Trajectory of the moving object is refined using a Kalman filter-based prediction method. The proposed algorithm has been used successfully to analyze one of the complex infant neurological examinations often referred to as Hammersmith lateral tilting test. This is an important test of the infant neurological assessment process, and this test is difficult to grade by visual observation. It has been shown in this paper that the proposed video object tracking algorithm can be used to analyze the videos of fast moving objects by incorporating application-specific information. For example, the proposed tracking algorithm can be used to assess lateral tilting test of the Hammersmith infant neurological examinations. The algorithm has been tested with several video recordings of this test which were captured at the neurodevelopment clinic of the SSKM Hospital, Kolkata, India during the period of the study. It is found that the proposed algorithm is capable of estimating the score for the test with high values of sensitivity and specificity. PMID:25096789
Path-following analysis of the dynamical response of a piecewise-linear capsule system
NASA Astrophysics Data System (ADS)
Páez Chávez, Joseph; Liu, Yang; Pavlovskaia, Ekaterina; Wiercigroch, Marian
2016-08-01
The dynamical response of a piecewise-linear capsule system is studied by means of path-following techniques in this paper. As the capsule model belongs to the class of piecewise-smooth dynamical systems involving impact and friction, a special care is taken in order to divide the trajectory of the system into a smooth vector field in each disjoint subregion. Specifically we study a two-sided drifting system focusing on directional control and energy consumption. We aim to address two practical problems which are maximizing the rate of progression and directional control of the system by following a typical period-1 trajectory. The one-parameter analysis shows that two types of bifurcations, grazing bifurcation and boundary-intersection crossing bifurcation are found, and the maximal rate of progression is achieved when the capsule performs the oscillations without sticking phases. In our two-parameter study, the control parameters for which the rate of progression is maximal are identified using fixed value of power consumption, and the curves which divide the motion of the capsule between forward and backward progression are obtained.
Strain analysis and strain path modelling in the Loch Tollie gneisses, Gairloch, NW Scotland
NASA Astrophysics Data System (ADS)
Odling, N. E.
A quantitative structural analysis is presented for the Loch Tullie gneisses of the Lewisian complex outcropping at Gairloch. The gneisses and the dykes they contain are folded into a large antiformal structure known as the Tollic Antiform. Quartz aggregates in quartzo-feldspathic gneisses have been used as finite strain markers in eleven specimens across the antiform. Two models, using rotational strain (simple shear) and irrotational strain (pure shear), are used to reconstruct the strain path. Results show that only the rotational strain model satisfies the strain data and the field evidence, and indicates a steeply northeast (75°) dipping shear plane and moderately northwest (55°) plunging shear direction, with a southwest-side-down sense of shear. A strain profile is constructed for the Tollie gneisses using the model and the attitude of gneissose layering. This shows increasing shear strain to the southwest to a maximum gamma value of approximately 8. The strain profile indicates a horizontal dextral displacement of 4.7 km and a vertical displacement of 6.8 km for the Tollie gneisses. The Tollie Antiform thus lies on the northeast margin of a large-scale shear zone, the main zone of deformation of which can be traced southwestwards some 4 km. Such a shear zone presents a major tectonic boundary within the Lewisian of northwest Scotland.
A multilevel path analysis of contact frequency between social network members
NASA Astrophysics Data System (ADS)
van den Berg, Pauline; Arentze, Theo; Timmermans, Harry
2012-04-01
Recently, there has been an increasing interest in the role of social networks in spatial-choice and travel behavior. It has been acknowledged that social activities and the travel for these activities can emerge from individuals' social networks and that social activities are responsible for an important portion of travel demand. The influence of information and communication technologies (ICT's) is also important in this respect. The purpose of the paper is to examine the effects of characteristics of egos and ego-alter relationships on the frequency of social interaction by different communication modes, using multilevel path analysis. The analyses are based on social network data collected in 2008 in the Eindhoven region in the Netherlands among 116 respondents. The results indicate a complementary relationship between contact frequencies by different modes. The contact frequencies of the different modes, especially face-to-face and telephone, can also be largely explained by the ego's personal characteristics and the type of relationship and the distance between ego and alter.
General framework for transfer path analysis: History, theory and classification of techniques
NASA Astrophysics Data System (ADS)
van der Seijs, Maarten V.; de Klerk, Dennis; Rixen, Daniel J.
2016-02-01
Transfer Path Analysis (TPA) designates the family of test-based methodologies to study the transmission of mechanical vibrations. Since the first adaptation of electric network analogies in the field of mechanical engineering a century ago, a multitude of TPA methods have emerged and found their way into industrial development processes. Nowadays the TPA paradigm is largely commercialised into out-of-the-box testing products, making it difficult to articulate the differences and underlying concepts that are paramount to understanding the vibration transmission problem. The aim of this paper is to derive and review a wide repertoire of TPA techniques from their conceptual basics, liberating them from their typical field of application. A selection of historical references is provided to align methodological developments with particular milestones in science. Eleven variants of TPA are derived from a unified framework and classified into three categories, namely classical, component-based and transmissibility-based TPA. Current challenges and practical aspects are discussed and reference is made to related fields of research.
First-principles analysis on Seebeck coefficient in zinc oxide nanowires for thermoelectric devices
NASA Astrophysics Data System (ADS)
Nakamura, K.
2016-03-01
The Seebeck coefficient of ZnO<0001> nanowires was simulated on the basis of first- principles calculation, to discuss the potential for future application to thermoelectric devices. Simulation procedure by means of the electronic band structure with one-dimensional periodic boundary condition was presented, and dependences of the Seebeck coefficient on temperature and carrier concentration have been investigated for many kinds of n- or p-doped ZnO<0001> nanowire models with 1.00-2.65 nm diameter. For the direct band-gap semiconducting models, a magnitude of the Seebeck coefficient increases gradually as temperature rises in the p-doped state, and a significant effect of miniaturization to nanowire on the Seebeck coefficient has been brought out, such as about 1000 µV/K in the p-doped state and -820 µV/K in the n-doped state for the (ZnO)24 nanowire model with 1 × 1017 cm-3 carrier concentration at room temperature. Similar characteristics of the Seebeck coefficient were observed for some indirect band-gap semiconducting models. At the end of this paper, the simulation was extended to the no band-gap conducting models with some modification.
ERIC Educational Resources Information Center
Shore, M. L.
1980-01-01
There are many uses for the shortest path algorithm presented which are limited only by our ability to recognize when a problem may be converted into the shortest path in a graph representation. (Author/TG)
Stress optical path difference analysis of off-axis lens ray trace footprint
NASA Astrophysics Data System (ADS)
Hsu, Ming-Ying; Chan, Chia-Yen; Lin, Wei-Cheng; Wu, Kun-Huan; Chen, Chih-Wen; Chan, Shenq-Tsong; Huang, Ting-Ming
2013-06-01
The mechanical and thermal stress on lens will cause the glass refractive index different, the refractive index of light parallel and light perpendicular to the direction of stress. The refraction index changes will introduce Optical Path Difference (OPD). This study is applying Finite Element Method (FEM) and optical ray tracing; calculate off axis ray stress OPD. The optical system stress distribution result is calculated from finite element simulation, and the stress coordinate need to rotate to optical path direction. Meanwhile, weighting stress to each optical ray path and sum the ray path OPD. The Z-direction stress OPD can be fitted by Zernike polynomial, the separated to sag difference, and rigid body motion. The fitting results can be used to evaluate the stress effect on optical component.
Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China
Yang, Zhiyong; Dong, Wenjie; Xiu, Jinfeng; Dai, Rufeng; Chou, Jieming
2015-01-01
Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a
Structural Path Analysis of Fossil Fuel Based CO2 Emissions: A Case Study for China.
Yang, Zhiyong; Dong, Wenjie; Xiu, Jinfeng; Dai, Rufeng; Chou, Jieming
2015-01-01
Environmentally extended input-output analysis (EEIOA) has long been used to quantify global and regional environmental impacts and to clarify emission transfers. Structural path analysis (SPA), a technique based on EEIOA, is especially useful for measuring significant flows in this environmental-economic system. This paper constructs an imports-adjusted single-region input-output (SRIO) model considering only domestic final use elements, and it uses the SPA technique to highlight crucial routes along the production chain in both final use and sectoral perspectives. The results indicate that future mitigation policies on household consumption should change direct energy use structures in rural areas, cut unreasonable demand for power and chemical products, and focus on urban areas due to their consistently higher magnitudes than rural areas in the structural routes. Impacts originating from government spending should be tackled by managing onsite energy use in 3 major service sectors and promoting cleaner fuels and energy-saving techniques in the transport sector. Policies on investment should concentrate on sectoral interrelationships along the production chain by setting up standards to regulate upstream industries, especially for the services, construction and equipment manufacturing sectors, which have high demand pulling effects. Apart from the similar methods above, mitigating policies in exports should also consider improving embodied technology and quality in manufactured products to achieve sustainable development. Additionally, detailed sectoral results in the coal extraction industry highlight the onsite energy use management in large domestic companies, emphasize energy structure rearrangement, and indicate resources and energy safety issues. Conclusions based on the construction and public administration sectors reveal that future mitigation in secondary and tertiary industries should be combined with upstream emission intensive industries in a
NASA Astrophysics Data System (ADS)
Hahne, Susanne; Ikonomov, Julian; Sokolowski, Moritz; Maass, Philipp
2013-02-01
Methods of determining surface diffusion coefficients of molecules from signal fluctuations of a locally fixed probe are revisited and refined. Particular emphasis is put on the influence of the molecule's extent. In addition to the formerly introduced autocorrelation method and residence time method, we develop a further method based on the distribution of intervals between successive peaks in the signal. The theoretical findings are applied to scanning tunneling microscopy measurements of copper phthalocyanine (CuPc) molecules on the Ag(100) surface. We discuss advantages and disadvantages of each method and suggest a combination to obtain accurate results for diffusion coefficients.
Linear and nonlinear dynamic analysis of redundant load path bearingless rotor systems
NASA Technical Reports Server (NTRS)
Murthy, V. R.
1985-01-01
The bearingless rotorcraft offers reduced weight, less complexity and superior flying qualities. Almost all the current industrial structural dynamic programs of conventional rotors which consist of single load path rotor blades employ the transfer matrix method to determine natural vibration characteristics because this method is ideally suited for one dimensional chain like structures. This method is extended to multiple load path rotor blades without resorting to an equivalent single load path approximation. Unlike the conventional blades, it isk necessary to introduce the axial-degree-of-freedom into the solution process to account for the differential axial displacements in the different load paths. With the present extension, the current rotor dynamic programs can be modified with relative ease to account for the multiple load paths without resorting to the equivalent single load path modeling. The results obtained by the transfer matrix method are validated by comparing with the finite element solutions. A differential stiffness matrix due to blade rotation is derived to facilitate the finite element solutions.
Werner, Kent; Bosson, Emma; Berglund, Sten
2006-12-01
Safety assessment related to the siting of a geological repository for spent nuclear fuel deep in the bedrock requires identification of potential flow paths and the associated travel times for radionuclides originating at repository depth. Using the Laxemar candidate site in Sweden as a case study, this paper describes modeling methodology, data integration, and the resulting water flow models, focusing on the Quaternary deposits and the upper 150 m of the bedrock. Example simulations identify flow paths to groundwater discharge areas and flow paths in the surface system. The majority of the simulated groundwater flow paths end up in the main surface waters and along the coastline, even though the particles used to trace the flow paths are introduced with a uniform spatial distribution at a relatively shallow depth. The calculated groundwater travel time, determining the time available for decay and retention of radionuclides, is on average longer to the coastal bays than to other biosphere objects at the site. Further, it is demonstrated how GIS-based modeling can be used to limit the number of surface flow paths that need to be characterized for safety assessment. Based on the results, the paper discusses an approach for coupling the present models to a model for groundwater flow in the deep bedrock. PMID:17334050
Statistical Analysis for Multisite Trials Using Instrumental Variables with Random Coefficients
ERIC Educational Resources Information Center
Raudenbush, Stephen W.; Reardon, Sean F.; Nomi, Takako
2012-01-01
Multisite trials can clarify the average impact of a new program and the heterogeneity of impacts across sites. Unfortunately, in many applications, compliance with treatment assignment is imperfect. For these applications, we propose an instrumental variable (IV) model with person-specific and site-specific random coefficients. Site-specific IV…
Technology Transfer Automated Retrieval System (TEKTRAN)
Mannitol is a major deterioration product of Leuconstoc mesenteroides bacterial deterioration of both sugarcane and sugar beet. The effect of crystallization conditions on the mannitol partition coefficient (Keff) between impure sucrose syrup and crystal has been investigated in a batch laboratory c...
Bootsie: estimation of coefficient of variation of AFLP data by bootstrap analysis
Technology Transfer Automated Retrieval System (TEKTRAN)
Bootsie is an English-native replacement for ASG Coelho’s “DBOOT” utility for estimating coefficient of variation of a population of AFLP marker data using bootstrapping. Bootsie improves on DBOOT by supporting batch processing, time-to-completion estimation, built-in graphs, and a suite of export t...
Discordant MIC Analysis: A New Path to Licensure for Anti-infective Drugs
Follmann, Dean; Brittain, Erica; Powers, John H.
2013-01-01
Summary Background Evaluation of anti-infective drugs for licensure often relies on a noninferiority (NI) design where new drug B is noninferior to comparator drug A if the difference in success rates is reliably not worse than some fixed margin. The margin must be based on historical studies that estimate the magnitude of the benefit of drug A over placebo. This approach hampers drug development because the obligatory evidence for margin determination is often nonexistent. Purpose To develop a new method for licensure of anti-infective drugs when there is no historical evidence for reliable construction of the NI margin. Methods The MIC measures the minimum amount of drug that it takes to inhibit growth of bacteria in vitro. Patients who are infected with bacteria that have a low MIC to a given drug are expected to have good outcome when treated with that drug. Thus a differential effect of drug B versus drug A, if it exists, is likely to occur in patients whose pathogens have discordant MICs (e.g. low MIC for drug B, high MIC for drug A, or vice versa). A new paradigm for licensure of anti-infective drugs is proposed where a clinically acceptable NI margin is selected and licensure supported if the NI margin is met and B is reliably demonstrated superior to A in a subset of patients whose paired MICs favor B. The requirement for some evidence of superiority encourages a study that is carefully designed and executed. Results Simulations indicate the approach shows promise in realistic settings provided adequate data are available. A simulated example illustrates use of the methods. Limitations If the data have small sample size, weak MIC/success relationship, or high correlation between MIC-A, MIC-B, this procedure will have poor power. Conclusion Discordant MIC analysis may offer a novel path to licensure for certain anti-infective drugs. PMID:24287133
Job Stress and Related Factors Among Iranian Male Staff Using a Path Analysis Model
Azad-Marzabadi, Esfandiar; Gholami Fesharaki, Mohammad
2016-01-01
Background In recent years, job stress has been cited as a risk factor for some diseases. Objectives Given the importance of this subject, we established a new model for classifying job stress among Iranian male staff using path analysis. Materials and Methods This cross-sectional study was done on male staff in Tehran, Iran, 2013. The participants in the study were selected using a proportional stratum sampling method. The tools used included nine questionnaires (1- HSE questionnaire; 2- GHQ questionnaire; 3- Beck depression inventory; 4- Framingham personality type; 5- Azad-Fesharaki’s physical activity questionnaire; 6- Adult attachment style questionnaire; 7- Azad socioeconomic questionnaire; 8- Job satisfaction survey; and 9- demographic questionnaire). Results A total of 575 individuals (all male) were recruited for the study. Their mean (±SD) age was 33.49 (±8.9) and their mean job experience was 12.79 (±8.98) years. The pathway of job stress among Iranian male staff showed an adequate model fit (RMSEA=0.021, GFI=0.99, AGFI=0.97, P=0.136). In addition, the total effect of variables like personality type (β=0.283), job satisfaction (β=0.287), and age (β=0.108) showed a positive relationship with job stress, while variables like general health (β=-0.151) and depression (β=-0.242) showed the reverse effect on job stress. Conclusions According to the results of this study, we can conclude that our suggested model is suited to explaining the pathways of stress among Iranian male staff. PMID:27621934
Price, D.E.; Brereton, S.; Newton, M.; Moore, B.; Muirhead, D.; Pastrnak, J.; Prokosch, D.; Spence, B.; Towle, R.
2000-09-05
POV-Ray Ricochet Tracker is a freeware computer code developed to analyze high-speed fragment ricochet trajectory paths in complex 3-D areas such as explosives tiring chambers, facility equipment rooms, or shipboard Command and Control Centers. The code analyzes as many as millions of individual fragment trajectory paths in three dimensions and tracks these trajectory paths for up to four bounces through the three-dimensional model. It allows determination of the probabilities of hitting any designated areas or objects in the model. It creates renderings of any ricochet flight paths of interest in photo realistic renderings of the 3-D model. POV-Ray Ricochet Tracker is a customized version of the Persistence of Vision{trademark} Ray-Tracer (POV-Ray{trademark}) version 3.02 code for the Macintosh{trademark} Operating System (MacOS{trademark}). POV-Ray is a third generation graphics engine that creates three-dimensional, very high quality (photo-realistic) images with realistic reflections, shading, textures, perspective, and other effects using a rendering technique called ray-tracing. It reads a text tile that describes the objects, lighting, and camera location in a scene and generates an image of that scene from the viewpoint of the camera. More information about POV-Ray, including the executable and source code, may be found at http://www.povray.org. The customized code (POV-Ray Shrapnel Tracker, V3.02-Custom Build 2) generates individual fragment trajectory paths at any desired angle intervals in three dimensions. The code tracks these trajectory paths through any complex three-dimensional space, and outputs detailed data for each ray as requested by the user. The output may include trajectory source location, initial direction of each trajectory, vector data for each bounce point, and any impacts with designated model target surfaces during any trajectory segment (direct path or reflected paths). This allows determination of the three-dimensional trajectory of
NASA Astrophysics Data System (ADS)
Wang, Fang
2016-06-01
In order to detect and quantify asymmetry of two time series, a novel cross-correlation coefficient is proposed based on recent asymmetric detrended cross-correlation analysis (A-DXA), which we called A-DXA coefficient. The A-DXA coefficient, as an important extension of DXA coefficient ρ D X A , contains two directional asymmetric cross-correlated indexes, describing upwards and downwards asymmetric cross-correlations, respectively. By using the information of directional covariance function of two time series and directional variance function of each series itself instead of power-law between the covariance function and time scale, the proposed A-DXA coefficient can well detect asymmetry between the two series no matter whether the cross-correlation is significant or not. By means of the proposed A-DXA coefficient conducted over the asymmetry for California electricity market, we found that the asymmetry between the prices and loads is not significant for daily average data in 1999 yr market (before electricity crisis) but extremely significant for those in 2000 yr market (during the crisis). To further uncover the difference of asymmetry between the years 1999 and 2000, a modified H statistic (MH) and ΔMH statistic are proposed. One of the present contributions is that the high MH values calculated for hourly data exist in majority months in 2000 market. Another important conclusion is that the cross-correlation with downwards dominates over the whole 1999 yr in contrast to the cross-correlation with upwards dominates over the 2000 yr.
Wang, Fang
2016-06-01
In order to detect and quantify asymmetry of two time series, a novel cross-correlation coefficient is proposed based on recent asymmetric detrended cross-correlation analysis (A-DXA), which we called A-DXA coefficient. The A-DXA coefficient, as an important extension of DXA coefficient ρDXA, contains two directional asymmetric cross-correlated indexes, describing upwards and downwards asymmetric cross-correlations, respectively. By using the information of directional covariance function of two time series and directional variance function of each series itself instead of power-law between the covariance function and time scale, the proposed A-DXA coefficient can well detect asymmetry between the two series no matter whether the cross-correlation is significant or not. By means of the proposed A-DXA coefficient conducted over the asymmetry for California electricity market, we found that the asymmetry between the prices and loads is not significant for daily average data in 1999 yr market (before electricity crisis) but extremely significant for those in 2000 yr market (during the crisis). To further uncover the difference of asymmetry between the years 1999 and 2000, a modified H statistic (MH) and ΔMH statistic are proposed. One of the present contributions is that the high MH values calculated for hourly data exist in majority months in 2000 market. Another important conclusion is that the cross-correlation with downwards dominates over the whole 1999 yr in contrast to the cross-correlation with upwards dominates over the 2000 yr. PMID:27368774
Analysis of segregation trends observed in iron meteorites using measured distribution coefficients
NASA Astrophysics Data System (ADS)
Sellamuthu, R.; Goldstein, J. I.
1985-02-01
Fe-Ni alloys of meteoritic composition were solidified by a plane front solidification technique. Distribution coefficients of Ni, P, Ir, Ge, and Cu were determined from the composition data of the plane front solidified alloys. Equations that describe the distribution coefficients (P, Ni, Ir, Ge, and Cu) as a function of S and P content as well as S to P ratio were used to calculate solute partitioning between solid and liquid during the solidification of IIAB, IIIAB, and IVA parent bodies. The calculated P versus Ni, Ir versus Ni, Ge versus Ni, and Cu versus Ni trends are in good agreement with the observed meteorite data for each chemical group. It is concluded that each chemical group formed as a single molten pool in a parent body and that solute partitioning that occurred during solidification is responsible for the observed compositional trends within a single meteorite group.
Slip flow coefficient analysis in water hydraulics gear pump for environmental friendly application
NASA Astrophysics Data System (ADS)
Yusof, A. A.; Wasbari, F.; Zakaria, M. S.; Ibrahim, M. Q.
2013-12-01
Water hydraulics is the sustainable option in developing fluid power systems with environmental friendly approach. Therefore, an investigation on water-based external gear pump application is being conducted, as a low cost solution in the shifting effort of using water, instead of traditional oil hydraulics in fluid power application. As the gear pump is affected by fluid viscosity, an evaluation has been conducted on the slip flow coefficient, in order to understand to what extent the spur gear pump can be used with water-based hydraulic fluid. In this paper, the results of a simulated study of variable-speed fixed displacement gear pump are presented. The slip flow coefficient varies from rotational speed of 250 RPM to 3500 RPM, and provides volumetric efficiency ranges from 9 % to 97% accordingly.
Analysis of segregation trends observed in iron meteorites using measured distribution coefficients
NASA Technical Reports Server (NTRS)
Sellamuthu, R.; Goldstein, J. I.
1985-01-01
Fe-Ni alloys of meteoritic composition were solidified by a plane front solidification technique. Distribution coefficients of Ni, P, Ir, Ge, and Cu were determined from the composition data of the plane front solidified alloys. Equations that describe the distribution coefficients (P, Ni, Ir, Ge, and Cu) as a function of S and P content as well as S to P ratio were used to calculate solute partitioning between solid and liquid during the solidification of IIAB, IIIAB, and IVA parent bodies. The calculated P versus Ni, Ir versus Ni, Ge versus Ni, and Cu versus Ni trends are in good agreement with the observed meteorite data for each chemical group. It is concluded that each chemical group formed as a single molten pool in a parent body and that solute partitioning that occurred during solidification is responsible for the observed compositional trends within a single meteorite group.
NASA Astrophysics Data System (ADS)
Deng, Wei; Wang, Jun
2015-06-01
We investigate and quantify the multifractal detrended cross-correlation of return interval series for Chinese stock markets and a proposed price model, the price model is established by oriented percolation. The return interval describes the waiting time between two successive price volatilities which are above some threshold, the present work is an attempt to quantify the level of multifractal detrended cross-correlation for the return intervals. Further, the concept of MF-DCCA coefficient of return intervals is introduced, and the corresponding empirical research is performed. The empirical results show that the return intervals of SSE and SZSE are weakly positive multifractal power-law cross-correlated, and exhibit the fluctuation patterns of MF-DCCA coefficients. The similar behaviors of return intervals for the price model is also demonstrated.
Orbit Optimization and Scattering Coefficient Analysis for the Proposed GLORIA System
NASA Technical Reports Server (NTRS)
Welch, Bryan
2004-01-01
This paper investigates the optimization of an orbit for a Low-Earth Orbiting (LEO) satellite for coastal coverage over Antarctic and United States shorelines as part of the Geostationary/Low-Earth Orbiting Radar Image Acquisition (GLORIA) System. Simulations over a range of orbital parameters are performed to determine the optimal orbit. Scattering coefficients are computed for the optimal orbit throughout the day and characterized to compare various scenarios for which link budget comparisons could then be made.
Analysis of lifetime of wireless sensor network with base station moving on different paths
NASA Astrophysics Data System (ADS)
Singh, Ashutosh Kumar; Purohit, N.; Varma, S.
2014-05-01
Energy saving is the top most requirement of the wireless sensor network (WSN) for making it a cost effective technology. In this direction, minimisation of the distance between the communicating nodes should be an obvious choice, as it consumes the biggest chunk of the node energy. But the stationary nature of nodes (including the base station) in the standard WSN does not allow it; thus, the provision of a moving base station has been recently introduced. A few schemes with moving base station have already been developed but they suffer from several drawbacks, for example, the path over which the base station can move has not been considered which is highly unfeasible. An efficient and implementable moving strategy is needed to be developed, which is the primary goal of the present work. The fuzzy logic inference mechanism has been developed and the performance of the same is illustrated in terms of WSN lifetime. Lifetime of a WSN depends on many factors, for example, residual energy of nodes, distance between communicating nodes and base station, etc. Ability of fuzzy logic theory to address more than one factor simultaneously gives it an upper edge over other alternatives. The present work explores the possibilities of building either a circular shaped or a cross-shaped path in the deployment area. A relative study of the movement of base station on these paths has been presented. Simulation results show that the cross path always give better performance than circular path and the lifetime improves with increase in the length of the predefined path.
NASA Technical Reports Server (NTRS)
Ruf, Joseph H.
1992-01-01
Phase 2+ Space Shuttle Main Engine powerheads, E0209 and E0215 degraded their main combustion chamber (MCC) liners at a faster rate than is normal for phase 2 powerheads. One possible cause of the accelerated degradation was a reduction of coolant flow through the MCC. Hardware changes were made to the preburner fuel leg which may have reduced the resistance and, therefore, pulled some of the hydrogen from the MCC coolant leg. A computational fluid dynamics (CFD) analysis was performed to determine hydrogen flow path resistances of the phase 2+ fuel preburner injector elements relative to the phase 2 element. FDNS was implemented on axisymmetric grids with the hydrogen assumed to be incompressible. The analysis was performed in two steps: the first isolated the effect of the different inlet areas and the second modeled the entire injector element hydrogen flow path.
NASA Astrophysics Data System (ADS)
Pelkey, Ramona K.
Gender, ethnicity, family economic status, reading score, mathematics score, and number of science semesters successfully completed were examined for their contributory role to a student's science score on a high-stakes, high school exit examination. Path analysis and analysis of variance procedures were used to quantify each variable's influence on science score. Gender, ethnicity, and family economic status were found to be moderators while reading proved to mediate within the model. The path model was created using a calibration sample and cross-validated using a hold-out validation sample. Bootstrapping was used to verify the goodness of fit of the model. A predictive equation explained 66% (R2 = .66) of the variance in observed TAKS science score.
NASA Astrophysics Data System (ADS)
Narayan, Raghuram
1997-12-01
The main topics in this dissertation are (a) Investigation of Electro-Optic (EO) coefficient variation in lithium niobate and (b) the design, fabrication and analysis of coplanar waveguide resonant electrodes for EO modulators. An optical sampling technique is used to determine the EO coefficient variations in lithium niobate processed using the titanium in-diffusion technique and the Annealed Proton Exchange (APE) technique. A spatial mapping of the EO coefficients in lithium niobate is presented. The measurements enable us to quantitatively estimate the reduction in the EO coefficient as a function of the processing conditions. The results clearly indicate that samples processed using titanium in-diffusion show no degradation of the EO coefficient. Samples processed using the APE technique display a dramatic drop in the processed region immediately after the proton exchange step. Thermal annealing is shown to restore the EO coefficient in the proton exchanged regions. But the efficacy of thermal annealing is dependent on the initial proton exchange process. Prolonged thermal annealing is effective in restoring the EO coefficients provided the initial proton exchange depth is less than 1.5/mu m. Coplanar Waveguide (CPW) is a popular planar transmission line because of its tight confinement and non-dispersive nature at high frequencies (>60 GHz). In this dissertation, several CPW resonant electrodes have been fabricated, tested and analyzed. The advantage of CPW resonant electrode structure is that there is an enhancement in the field strength by a factor proportional to /sqrt[Q], where Q is the quality factor of the resonator. The dis-advantage is that the device is narrow-band in its frequency response. The focus of this dissertation is to investigate the design and fabrication issues related to CPW resonators. The results indicate the need for better design tools to properly predict the performance of the resonator and in general CPW structures. The measurements
Endo, Satoshi
2016-08-10
Narcosis occurs as a result of the accumulation of chemicals in the phospholipid membrane. The toxic threshold concentration in the membrane is thought to be relatively constant across different chemicals and species. Hence, estimating chemical concentrations in the membrane is expected to reduce the variability of narcotic critical body residue (CBR) data. In this study, a high quality CBR dataset for three aquatic species reported recently in the literature was evaluated with the internal equilibrium distribution concept. The raw wet-weight-based CBR values were converted to membrane-weight-based CBR values by assuming that the chemical is distributed in storage lipids, membranes, proteins, and water according to the respective equilibrium partition coefficients. Several sets of partition coefficients were compared for this analysis. The results were consistent with the notion that the use of a structural protein instead of serum albumin as a surrogate for the body protein fraction could reduce the variability of CBRs. Partition coefficients predicted by polyparameter linear free energy relationships (PP-LFERs) reduced the variability of CBRs as much as or even more than experimental partition coefficients did. It is suggested that CBR data for chemicals with larger structural diversity and biological species with more distinct compositions are needed to evaluate further the equilibrium distribution concept and the constant membrane threshold hypothesis. PMID:27136717
Feasibility Analysis of Improving On-Campus Learning Paths via a Depth Sensor
ERIC Educational Resources Information Center
Pan, Wen-Fu; Tu, Shih-Chun; Chien, Mei-Ying
2014-01-01
This research aims to apply a depth sensor to create a human-body-sensing context for outdoor learning paths; it is conducted by incorporating both quasi-experiment and survey to compare students' cognitive learning outcome within the context and understand students' attitudes toward the context created. The result of ANCOVA indicates…
Numerical analysis of the crack growth path in the cement mantle of the reconstructed acetabulum.
Benbarek, Smaïl; Bachir Bouiadjra, Bel Abbes; El Mokhtar, Bouziane Mohamed; Achour, Tarik; Serier, Boualem
2013-01-01
In this study, we use the finite element method to analyze the propagation's path of the crack in the orthopedic cement of the total hip replacement. In fact, a small python statement was incorporated with the Abaqus software to do in loop the following operations: extracting the crack propagation direction from the previous study using the maximal circumferential stresses criterion, drawing the new path, meshing and calculating again (stresses and fracture parameters). The loop is broken when the user's desired crack length is reached (number of propagations) or the value of the mode I stress intensity factor is negative. Results show that the crack propagation's path can be influenced by human body posture. The existing of a cavity in the vicinity of the crack can change its propagation path or can absolutely attract it enough to meet it. Crack can propagate in the outward direction (toward the acetabulum bone) and cannot propagate in the opposite direction, the mode I stress intensity factor increases with the crack length and that of mode II vanishes. PMID:25428108
ERIC Educational Resources Information Center
Ritzhaupt, Albert D.; Dawson, Kara; Cavanaugh, Cathy
2012-01-01
The purpose of this research was to examine the effects of teachers' characteristics, school characteristics, and contextual characteristics on classroom technology integration and teacher use of technology as mediators of student use of technology. A research-based path model was designed and tested based on data gathered from 732 teachers from…
Morphological Awareness in Literacy Acquisition of Chinese Second Graders: A Path Analysis
ERIC Educational Resources Information Center
Zhang, Haomin
2016-01-01
The present study tested a path diagram regarding the contribution of morphological awareness (MA) to early literacy acquisition among Chinese-speaking second graders (N = 123). Three facets of MA were addressed, namely derivational awareness, compound awareness and compound structure awareness. The model aimed to test a theory of causal order…
LASER-BASED, LONG PATH MONITORING OF AMBIENT GASES, ANALYSIS OF TWO SYSTEMS
New long path absorption techniques for measurement of ambient O3 and CO have recently been demonstrated using a CO2 laser and a semiconductor diode laser, respectively. For the CO2 laser system the use of closely spaced wavelengths minimizes system drift and simplifies the deter...
Combined Study and Work Paths in VET: Policy Implications and Analysis.
ERIC Educational Resources Information Center
Dwyer, Peter; Harwood, Aramiha; Costin, Glen; Landy, Mark; Towsty, Lidia; Wyn, Johanna
This study investigated ways in which Australian vocational education and training (VET) students in the 1990s combined study and work to prepare for future long-term career paths. The study was conducted throughout 1998 in three technical and further education (TAFE) institutes in three states, using the following methods: a survey of about 1,400…
Knowledge Monitoring, Goal Orientations, Self-Efficacy, and Academic Performance: A Path Analysis
ERIC Educational Resources Information Center
Al-Harthy, Ibrahim S.; Was, Christopher A.
2013-01-01
The purpose of this study was to examine the relationship between knowledge monitoring and motivation as defined by self-efficacy and goal orientations. A path model was proposed to hypothesize the causal relations among predictors of the students' total score in the Educational Psychology course. The sample consisted of undergraduate…
ERIC Educational Resources Information Center
Lund, Stefan
2008-01-01
Decentralisation policy in Sweden emphasises school capitation allowance, the local upper secondary schools' decision-making and pupils' choices in contrast to previous bureaucratic governing. The aim of this article is to discuss how pupils' educational choice paths are a part of the different kinds of integration and differentiation processes…
Benchmark 1 - Nonlinear strain path forming limit of a reverse draw: Part C: Benchmark analysis
NASA Astrophysics Data System (ADS)
Wu, Xin
2013-12-01
This document summarizes the Benchmark 1 results and presents all submitted FEA results from 9 participants and experimental results in 104 figures, including load-displacement curves, strain path evolutions over four specified blank positions, and deformed under different forming settings: three sheet materials, three blank geometries (width), and two shim heights that alter the strain paths and the two stage strain ratio with major strain path changes. The fourth specified point corresponds to the location of localized necking. The FEA models and software/hardware used by the participants are provided. The rich data presented from both simulation and experimental measurement provide valuable information on the current interest in material plasticity/formability and their prediction under continuous non-linear strain path that exist in this reverse draw process. At the request of the author, and Proceedings Editor, a corrected and updated version of this paper was published on January 2, 2014. The Corrigendum attached to the updated article PDF contains a list of the changes made to the original published version.
Analysis of swarm coefficients in a gas for bi-modal electron energy distribution model
NASA Astrophysics Data System (ADS)
Govinda-Raju, Gorur
2015-03-01
Cross sections for collision between electrons and neutrals in a gas discharge are essential for theoretical and computational developments. They are also required to interpret and analyze the results of experimental studies on swarm parameters namely drift velocity, characteristic energy, and ionization and attachment coefficients. The cross sections and swarm coefficients are interconnected through the most important electron energy distribution function. The traditional method of solving the Boltzmann equation numerically yields the required distribution (EEDF). However there are many situations where a simpler approach is desirable for deriving the energy distribution analytically. Energy distribution in non-uniform electric fields, in crossed electric and magnetic fields, breakdown in mixtures of gases for electrical power or plasma applications, calculation of longitudinal diffusion coefficients are examples. In other studies the swarm parameters are employed to derive the cross sections in an unfolding procedure that also involves the energy distribution function. Application of Boltzmann solution method, though more rigorous, consumes enormous efforts in time and technical expertise. In an attempt to provide a simpler method the present author has previously suggested a bimodal electron energy distribution in gases. In this paper the author has generalized the idea of bi-modal energy distribution by considering a model gas with representative cross sections and adopted numerical methods for greater accuracy. The parameters considered are the nature of the two distributions, their relative ratio, and the dependence of cross sections on electron energy. A new method for determining the combination of distributions has been shown to be adequate for calculation of swarm parameters. The results for argon are shown to yield very good agreement with available experimental and theoretical values.
Bagli, Stefano; Geneletti, Davide; Orsi, Francesco
2011-04-15
Least-cost path analysis (LCPA) allows designers to find the 'cheapest' way to connect two locations within a cost surface, which can be computed by combining multiple criteria, and therefore by accounting for different issues (environmental impact, economic investment, etc.). This procedure can be easily implemented with modern Geographic Information System (GIS) technologies, and consequently it has been widely employed to support planning and design of different types of linear infrastructures, ranging from roads to pipelines. This paper presents an approach based on the integration of multicriteria evaluation (MCE) and LCPA to identify the most suitable route for a 132 kV power line. Criteria such as cost, visibility, population density, and ecosystem naturalness were used for the analysis. Firstly, spatial MCE and LCPA were combined to generate cost surfaces, and to identify alternative paths. Subsequently, MCE was used to compare the alternatives, and rank them according to their overall suitability. Finally, a sensitivity analysis allowed the stability of the results to be tested and the most critical factors of the evaluation to be detected. The study found that small changes in the location of the power line start and end points can result in significantly different paths, and consequently impact levels. This suggested that planners should always consider alternative potential locations of terminals in order to identify the best path. Furthermore, it was shown that the use of different weight scenarios may help making the model adaptable to varying environmental and social contexts. The approach was tested on a real-world case study in north-eastern Italy.
a Latent Variable Path Analysis Model of Secondary Physics Enrollments in New York State.
NASA Astrophysics Data System (ADS)
Sobolewski, Stanley John
The Percentage of Enrollment in Physics (PEP) at the secondary level nationally has been approximately 20% for the past few decades. For a more scientifically literate citizenry as well as specialists to continue scientific research and development, it is desirable that more students enroll in physics. Some of the predictor variables for physics enrollment and physics achievement that have been identified previously includes a community's socioeconomic status, the availability of physics, the sex of the student, the curriculum, as well as teacher and student data. This study isolated and identified predictor variables for PEP of secondary schools in New York. Data gathered by the State Education Department for the 1990-1991 school year was used. The source of this data included surveys completed by teachers and administrators on student characteristics and school facilities. A data analysis similar to that done by Bryant (1974) was conducted to determine if the relationships between a set of predictor variables related to physics enrollment had changed in the past 20 years. Variables which were isolated included: community, facilities, teacher experience, number of type of science courses, school size and school science facilities. When these variables were isolated, latent variable path diagrams were proposed and verified by the Linear Structural Relations computer modeling program (LISREL). These diagrams differed from those developed by Bryant in that there were more manifest variables used which included achievement scores in the form of Regents exam results. Two criterion variables were used, percentage of students enrolled in physics (PEP) and percent of students enrolled passing the Regents physics exam (PPP). The first model treated school and community level variables as exogenous while the second model treated only the community level variables as exogenous. The goodness of fit indices for the models was 0.77 for the first model and 0.83 for the second
Existence of Compressible Current-Vortex Sheets: Variable Coefficients Linear Analysis
NASA Astrophysics Data System (ADS)
Trakhinin, Yuri
2005-09-01
We study the initial-boundary value problem resulting from the linearization of the equations of ideal compressible magnetohydrodynamics and the Rankine-Hugoniot relations about an unsteady piecewise smooth solution. This solution is supposed to be a classical solution of the system of magnetohydrodynamics on either side of a surface of tangential discontinuity (current-vortex sheet). Under some assumptions on the unperturbed flow, we prove an energy a priori estimate for the linearized problem. Since the tangential discontinuity is characteristic, the functional setting is provided by the anisotropic weighted Sobolev space W21,σ. Despite the fact that the constant coefficients linearized problem does not meet the uniform Kreiss-Lopatinskii condition, the estimate we obtain is without loss of smoothness even for the variable coefficients problem and nonplanar current-vortex sheets. The result of this paper is a necessary step in proving the local-in-time existence of current-vortex sheet solutions of the nonlinear equations of magnetohydrodynamics.
Return period adjustment for runoff coefficients based on analysis in undeveloped Texas watersheds
Dhakal, Nirajan; Fang, Xing; Asquith, William H.; Cleveland, Theodore G.; Thompson, David B.
2013-01-01
The rational method for peak discharge (Qp) estimation was introduced in the 1880s. The runoff coefficient (C) is a key parameter for the rational method that has an implicit meaning of rate proportionality, and the C has been declared a function of the annual return period by various researchers. Rate-based runoff coefficients as a function of the return period, C(T), were determined for 36 undeveloped watersheds in Texas using peak discharge frequency from previously published regional regression equations and rainfall intensity frequency for return periods T of 2, 5, 10, 25, 50, and 100 years. The C(T) values and return period adjustments C(T)/C(T=10 year) determined in this study are most applicable to undeveloped watersheds. The return period adjustments determined for the Texas watersheds in this study and those extracted from prior studies of non-Texas data exceed values from well-known literature such as design manuals and textbooks. Most importantly, the return period adjustments exceed values currently recognized in Texas Department of Transportation design guidance when T>10 years.
NASA Technical Reports Server (NTRS)
Kyser, A. C.
1977-01-01
Results are presented from an elementary analysis of the effect of sweep angle on the idealized structural weight of swept wings, with cruise Mach number M and lift coefficient C sub L as parameters. The analysis indicates that sweep is unnecessary for cruise Mach numbers below about 0.80, whereas for the higher subsonic speeds, a well defined minimum-weight condition exists at a sweep angle in the neighborhood of 35 deg or 40 deg, depending on M and C sub L. The results further indicate that wing-structure weight increases sharply with Mach number in the high subsonic range, with Mach 0.85 wings weighing half again as much as Mach 0.75 wings. Weight is also shown to increase with cruise lift coefficient, but the effect is not strong for the usual range of design lift coefficients. Minimum wing-structure weight is found to occur at a ratio of thickness to normal chord of about 18 percent, but it is concluded that the thickness ratio for optimum wing design would probably lie in the range of 12 to 15 percent.
Analysis of climate paths reveals potential limitations on species range shifts.
Early, Regan; Sax, Dov F
2011-11-01
Forecasts of species endangerment under climate change usually ignore the processes by which species ranges shift. By analysing the 'climate paths' that range shifts might follow, and two key range-shift processes--dispersal and population persistence--we show that short-term climatic and population characteristics have dramatic effects on range-shift forecasts. By employing this approach with 15 amphibian species in the western USA, we make unexpected predictions. First, inter-decadal variability in climate change can prevent range shifts by causing gaps in climate paths, even in the absence of geographic barriers. Second, the hitherto unappreciated trait of persistence during unfavourable climatic conditions is critical to species range shifts. Third, climatic fluctuations and low persistence could lead to endangerment even if the future potential range size is large. These considerations may render habitat corridors ineffectual for some species, and conservationists may need to consider managed relocation and augmentation of in situ populations. PMID:21955643
NASA Astrophysics Data System (ADS)
Jacob, Anaïs; Mehmanparast, Ali
2016-07-01
The effects of microstructure, grain and grain boundary (GB) properties on predicted damage paths and indicative crack propagation direction have been examined for a polycrystalline material using mesoscale finite element simulations. Numerical analyses were carried out on a compact tension specimen geometry containing granular mesh structures with random grain shapes and sizes of average diameter 100μm. Nanoindentation tests were performed to investigate the dependency of mesoscale hardness measurements on the indentation location with respect to grain and GB regions. Finite element results have shown that under tensile loading conditions, the predicted damage paths are very sensitive to the granular mesh structure, GB properties and individual grain properties. Furthermore, finite element results have revealed that the cracking mode (i.e., transgranular/intergranular) and maximum crack deviation angle are strongly dependent on the material microstructures employed in simulations.
Analysis of ONEDANT code package for the calculation of the Doppler coefficient of reactivity
Soares, I. ); Miller, W.F.; Perry, R.T. )
1993-06-01
The viability of the use of the ONEDANT discrete ordinates code for the calculation of the Doppler coefficient of reactivity for a pressurized water reactor is investigated. The ONEDANT results are compared with benchmark results from a Monte Carlo code, MCNP-3A. A comparison with the results obtained using the CELL-2 and WIMS-AECL codes is also included. The influences of certain variables, such as spatial mesh, S[sub N] angular quadrature order, interaction convergence criterion, boundary conditions, P[sub N] order, and number of energy groups, are analyzed. An alternative benchmark calculation to the Monte Carlo result is attempted to provide some feel for the approximate accuracy of the Monte Carlo calculation. Such an alternative answer is important when less approximate methods are compared with these results.
NASA Astrophysics Data System (ADS)
Lee, Haw-Long; Chang, Win-Jin; Chen, Wen-Lih; Yang, Yu-Ching
2012-06-01
This paper numerically investigates the hyperbolic thermoelastic problem of an annular fin. The ambient convection heat transfer coefficient of the fin is assumed to be spatially varying. The major difficulty in dealing with such problems is the suppression of numerical oscillations in the vicinity of a jump discontinuity. An efficient numerical scheme involving hybrid application of Laplace transform and control volume method in conjunction with hyperbolic shape functions is used to solve the linear hyperbolic heat conduction equation. The transformed nodal temperatures are inverted to the physical quantities by using numerical inversion of the Laplace transform. Then the stress distributions in the annular fin are calculated subsequently. The results in the illustrated examples show that the application of hyperbolic shape functions can successfully suppress the numerical oscillations in the vicinity of jump discontinuities.
Standardized Regression Coefficients as Indices of Effect Sizes in Meta-Analysis
ERIC Educational Resources Information Center
Kim, Rae Seon
2011-01-01
When conducting a meta-analysis, it is common to find many collected studies that report regression analyses, because multiple regression analysis is widely used in many fields. Meta-analysis uses effect sizes drawn from individual studies as a means of synthesizing a collection of results. However, indices of effect size from regression analyses…
Levant, Ronald F; Stefanov, Dimitre G; Rankin, Thomas J; Halter, Margaret J; Mellinger, Chris; Williams, Christine M
2013-07-01
This study tested a theoretical model of one mediator and 4 moderators of the relationships between 2 masculinity variables (Traditional Masculinity Ideology and Gender Role Conflict) and Attitudes Toward Seeking Professional Psychological Services (Attitudes). Self-stigma was the hypothesized mediator, and the hypothesized moderators were (a) Depression, (b) General Self-efficacy, (c) Precontemplation, and (d) Barriers to Help-seeking. A sample of 654 men responded to an online survey of 9 questionnaires. After evaluating mediation in the absence of moderation, moderated path analyses were conducted for each moderator. The relationship between Traditional Masculinity Ideology and Attitudes was partially mediated by Self-stigma, whereas that between Gender Role Conflict and Attitudes was completely mediated. No indirect or direct paths involving Gender Role Conflict were moderated by any moderators. Both Depression and Barriers to Help-seeking demonstrated mediated moderation by moderating both Stage 1 (the path from Traditional Masculinity Ideology to Self-stigma) of the mediated relationships and the direct effects between Traditional Masculinity Ideology and Attitudes. Precontemplation moderated the direct effect between Traditional Masculinity Ideology and Attitudes. The findings suggest that the relationships between masculinity variables and men's negative help-seeking attitudes may be better understood through their relationships with other variables that serve as mediators and moderators. Findings from the present study may offer some direction in the design of interventions to remediate men's negative help-seeking attitudes. PMID:23668728
NASA Astrophysics Data System (ADS)
Amirataee, Babak; Montaseri, Majid; Sanikhani, Hadi
2015-07-01
Reference evapotranspiration (ET0) is considered a key parameter for evaluating the climatic changes as well as spatial and temporal patterns of parameters influencing the eco-hydrological processes. The analysis of trend variations of this index can be used to determine appropriate strategies in planning and management of water resources. In this paper, the trend variations of monthly and annual ET0 in Urmia Lake basin, located in the northwest of Iran, have been analyzed using data from 14 synoptic stations in the study area. Regarding the significant effect of autocorrelation coefficients with different lags on trend variations of ET0, this paper has resorted to modified Mann-Kendall test via eliminating the significance effect of autocorrelation coefficients with different lags to analyze the trend variations. Furthermore, Theil-Sen estimator has been used to determine the slope of trend line of ET0. The results indicated an increasing trend in ET0 values at all the studied stations. Having used the modified Mann-Kendall test, the values of significant increasing (positive) trend, which were estimated using common Mann-Kendall test, dramatically decreased. As such, the values of only 7 stations have been significant at 95 % level. The results confirmed the need for eliminating the significance effect of autocorrelation coefficients with different lags to determine and evaluate the trend of hydrological variables.
Kim, Isok
2014-01-01
This study used a path analytic technique to examine associations among critical ethnic awareness, racial discrimination, social support, and depressive symptoms. Using a convenience sample from online survey of Asian American adults (N = 405), the study tested 2 main hypotheses: First, based on the empowerment theory, critical ethnic awareness would be positively associated with racial discrimination experience; and second, based on the social support deterioration model, social support would partially mediate the relationship between racial discrimination and depressive symptoms. The result of the path analysis model showed that the proposed path model was a good fit based on global fit indices, χ²(2) = 4.70, p = .10; root mean square error of approximation = 0.06; comparative fit index = 0.97; Tucker-Lewis index = 0.92; and standardized root mean square residual = 0.03. The examinations of study hypotheses demonstrated that critical ethnic awareness was directly associated (b = .11, p < .05) with the racial discrimination experience, whereas social support had a significant indirect effect (b = .48; bias-corrected 95% confidence interval [0.02, 1.26]) between the racial discrimination experience and depressive symptoms. The proposed path model illustrated that both critical ethnic awareness and social support are important mechanisms for explaining the relationship between racial discrimination and depressive symptoms among this sample of Asian Americans. This study highlights the usefulness of the critical ethnic awareness concept as a way to better understand how Asian Americans might perceive and recognize racial discrimination experiences in relation to its mental health consequences. PMID:24491128
Is the Meta-Analysis of Correlation Coefficients Accurate When Population Correlations Vary?
ERIC Educational Resources Information Center
Field, Andy P.
2005-01-01
One conceptualization of meta-analysis is that studies within the meta-analysis are sampled from populations with mean effect sizes that vary (random-effects models). The consequences of not applying such models and the comparison of different methods have been hotly debated. A Monte Carlo study compared the efficacy of Hedges and Vevea's…
A meta-analysis of the canopy light extinction coefficient in terrestrial ecosystems
NASA Astrophysics Data System (ADS)
Zhang, Liangxia; Hu, Zhongmin; Fan, Jiangwen; Zhou, Decheng; Tang, Fengpei
2014-12-01
The canopy light extinction coefficient ( K) is a key factor in affecting ecosystem carbon, water, and energy processes. However, K is assumed as a constant in most biogeochemical models owing to lack of in-site measurements at diverse terrestrial ecosystems. In this study, by compiling data of K measured at 88 terrestrial ecosystems, we investigated the spatiotemporal variations of this index across main ecosystem types, including grassland, cropland, shrubland, broadleaf forest, and needleleaf forest. Our results indicated that the average K of all biome types during whole growing season was 0.56. However, this value in the peak growing season was 0.49, indicating a certain degree of seasonal variation. In addition, large variations in K exist within and among the plant functional types. Cropland had the highest value of K (0.62), followed by broadleaf forest (0.59), shrubland (0.56), grassland (0.50), and needleleaf forest (0.45). No significant spatial correlation was found between K and the major environmental factors, i.e., mean annual precipitation, mean annual temperature, and leaf area index (LAI). Intra-annually, significant negative correlations between K and seasonal changes in LAI were found in the natural ecosystems. In cropland, however, the temporal relationship was site-specific. The ecosystem type specific values of K and its temporal relationship with LAI observed in this study may contribute to improved modeling of global biogeochemical cycles.
SVD principle analysis and fault diagnosis for bearings based on the correlation coefficient
NASA Astrophysics Data System (ADS)
Qiao, Zijian; Pan, Zhengrong
2015-08-01
Aiming at solving the existing sharp problems by using singular value decomposition (SVD) in the fault diagnosis of rolling bearings, such as the determination of the delay step k for creating the Hankel matrix and selection of effective singular values, the present study proposes a novel adaptive SVD method for fault feature detection based on the correlation coefficient by analyzing the principles of the SVD method. This proposed method achieves not only the optimal determination of the delay step k by means of the absolute value {{r}k} of the autocorrelation function sequence of the collected vibration signal, but also the adaptive selection of effective singular values using the index ρ corresponding to useful component signals including weak fault information to detect weak fault signals for rolling bearings, especially weak impulse signals. The effectiveness of this method has been verified by contrastive results between the proposed method and traditional SVD, even using the wavelet-based method through simulated experiments. Finally, the proposed method has been applied to fault diagnosis for a deep-groove ball bearing in which a single point fault located on either the inner or outer race of rolling bearings is obtained successfully. Therefore, it can be stated that the proposed method is of great practical value in engineering applications.
Wavelet coefficient analysis for the quantitative determination of damage in tendons and cables
NASA Astrophysics Data System (ADS)
Rizzo, Piervincenzo; Lanza di Scalea, Francesco
2005-05-01
Wires, bars, multi-wire strands made of steel or composite materials are widely used in civil infrastructures as tensioning members in cable-stayed bridges, suspension bridges and prestressed concrete. The health monitoring of these components is a long-standing challenge in the NDE community. In the last few years, the authors have been conducting a study on the application of ultrasonic guided waves for the structural health monitoring of bars and multi-wire strands. This paper presents an application of a signal processing technique based on the Discrete Wavelet Transform (DWT) for the detection and the quantification of damage (in the form of small notches) in loaded seven-wire steel strands. The DWT is applied to ultrasonic signals generated and detected via magnetostrictive transducers. The detection and the quantification of damage in the strands are accomplished by constructing and computing a damage index based on the variance and the root mean square of the wavelet coefficient vector of the ultrasonic damage signatures. It is shown that the logarithmic value of the damage index is linearly dependent on the damage size. In the last portion of the paper an eight-dimensional damage index is constructed and it is fed to an artificial neural network that classifies the size and the location of the notch.
Path analysis of the chronicity of depression using the comprehensive developmental model framework.
Fandiño-Losada, Andrés; Bangdiwala, Shrikant I; Lavebratt, Catharina; Forsell, Yvonne
2016-07-01
Background Depressive disorder is recognized as recurrent or chronic in the majority of affected individuals; but literature is not consistent about determinants of the disorder course. Aims To analyse the relationships between familial, personal and environmental characteristics in different life phases and their effects on the chronicity of depression in a population-based sample. Methods It was a longitudinal panel study with three waves (W1-W3) for 651 adult men and women with diagnosis of minor/major depression or dysthymia at W1 of the Swedish PART (mental health, work and relations) study. Risk factors and co-morbidities were assessed with questionnaires. The main outcome was an episode of minor/major depression or dysthymia at 10-12 years of follow-up (W3). Liability for depressive episodes was determined using exploratory structural equation modelling (SEM), following a path approach with step-wise specification searches. Results Most of the risk factors determined, directly or indirectly, depression severity at W3. Somatic trait anxiety, partner loss and other negative life events at W1, depressive symptoms at W2, and life difficulties and other dependent life events at W3 had direct effects on the outcome. Conclusions SEM model revealed complex and intertwined psychopathological pathways leading to chronicity of depression, given previous episodes, which could be assembled in two main mechanisms: a depressive-internalizing path and an adversity path comprised of life events. Pathways are simpler than those of depression occurrence, emphasizing the relevance of personality factors as depression determinants, and excluding disability levels, co-morbidities and social support. These novel findings need to be replicated in future studies. PMID:26925597
NASA Technical Reports Server (NTRS)
Ko, H. C.
1973-01-01
The wave-normal emissivity and the ray emissivity formulas for an electron moving along a helical path in a magnetoactive medium are presented. Simplified formulas for the case of an isotropic plasma are also given. Because of the helical motion of the electron, a difference exists between the radiated power per unit solid angle and the received power per unit solid angle. The relation between these two quantities in a magnetoactive medium is shown. Results are compared with those obtained by others, and the sources of discrepancies are pointed out.
Sorority Affiliation and Sexual Assault Victimization: Assessing Vulnerability Using Path Analysis.
Franklin, Cortney A
2016-07-01
The current research used survey data from 282 college women to investigate the relationship between female Greek membership and sexual assault victimization. Drawing from routine activity theory, low self-control, and social learning theory, this study tested a theoretical model that identified pertinent factors present among sorority environments to determine the relationships between Greek affiliation and sexual assault. Path analyses revealed that sorority women reported consuming more alcohol and with greater frequency, increased risk-taking behavior, delayed assessments of threat and responses to risk, and increased contact with fraternity men-all of which significantly predicted sexual assault. Future theory, research, and policy directions are proposed. PMID:26597086
NASA Technical Reports Server (NTRS)
Campbell, R. H.; Kolstad, R. B.; Holle, D. F.; Miller, T. J.; Krause, P.; Horton, K.; Macke, T.
1983-01-01
Path Pascal is high-level experimental programming language based on PASCAL, which incorporates extensions for systems and real-time programming. Pascal is extended to treat real-time concurrent systems.
NASA Astrophysics Data System (ADS)
Nagatomi, T.; Goto, K.
2005-11-01
An analytical approach was proposed for simultaneously determining an inelastic mean-free path (IMFP) and a surface excitation parameter (SEP) with absolute units by the analysis of an absolute experimental reflection electron energy loss spectrum. The IMFPs and SEPs in Ni were deduced for electrons of 300 to 3000 eV. The obtained IMFPs were in good agreement with those calculated using the TPP-2M equation. The Chen-type empirical formula was proposed for determining the SEP. The results confirmed the applicability of the present approach for determining the IMFP and SEP for medium-energy electrons.
NASA Technical Reports Server (NTRS)
Taylor, C. M.
1977-01-01
A ceramic/metallic aircraft gas turbine outer gas path seal designed to enable improved engine performance is studied. Flexible numerical analysis schemes suitable for the determination of transient temperature profiles and thermal stress distributions in the seal are outlined. An estimation of the stresses to which a test seal is subjected during simulated engine deceleration from sea level takeoff to idle conditions is made. Experimental evidence has indicated that the surface layer of the seal is probably subjected to excessive tensile stresses during cyclic temperature loading. This assertion is supported by the analytical results presented. Brief consideration is given to means of mitigating this adverse stressing.
[Influencing factors in measuring absorption coefficient of suspended particulate matters].
Yu, Xiao-long; Shen, Fang; Zhang, Jin-fang
2013-05-01
Absorption coefficient of suspended particulate matters in natural water is one of the key parameters in ocean color remote sensing. In order to study the influencing factors that affect the measurement, a series of experiments were designed to measure samples using transmittance method (T method), transmittance-reflectance method (T-R method) and absorptance method (A method). The results shows that absorption coefficient measured by the A method has a much lower error compared to the T method and T-R method due to influencing factors,such as filter-to-filter variations, water content of the filter, and homogeneity of filter load and so on. Another factor influence absorption coefficient is path-length amplification induced by multiple scattering inside the filter. To determine the path-length amplification, the true absorption was measured by AC-s (WetLabs). The linear fitting result shows that the mean path-length amplification is much higher for the A method than that of the T-R method and the T method (4.01 versus 2.20 and 2.32), and the corresponding correlation coefficient are 0.90, 0.87 and 0.80. For the A method and the T-R method, higher correlation coefficients are calculated when using polynomial fitting, and the value are 0.95 and 0.94. Analysis of the mean relative error caused by different influencing factors indicates that path-length amplification is the largest error source in measuring the absorption coefficient. PMID:23914523
DTI-based maximum density path analysis and classification of Alzheimer’s disease
Nir, Talia M.; Villalon-Reina, Julio E.; Prasad, Gautam; Jahanshad, Neda; Joshi, Shantanu H.; Toga, Arthur W.; Bernstein, Matt A.; Jack, Clifford R.; Weiner, Michael W.; Thompson, Paul M.
2014-01-01
Characterizing brain changes in Alzheimer’s disease (AD) is important for patient prognosis, and for assessing brain deterioration in clinical trials. In this diffusion tensor imaging study, we used a new fiber-tract modeling method to investigate white matter integrity in 50 elderly controls (CTL), 113 people with mild cognitive impairment (MCI), and 37 AD patients. After clustering tractography using an ROI atlas, we used a shortest path graph search through each bundle’s fiber density map to derive maximum density paths (MDPs), which we registered across subjects. We calculated the fractional anisotropy (FA) and mean diffusivity (MD) along all MDPs and found significant MD and FA differences between AD patients and CTL subjects as well as MD differences between CTL and late MCI subjects. MD and FA were also associated with widely used clinical scores (MMSE). As an MDP is a compact, low-dimensional representation of white matter organization, we tested the utility of DTI measures along these MDPs as features for support vector machine (SVM) based classification of AD. PMID:25444597
Advanced Launch System Multi-Path Redundant Avionics Architecture Analysis and Characterization
NASA Technical Reports Server (NTRS)
Baker, Robert L.
1993-01-01
The objective of the Multi-Path Redundant Avionics Suite (MPRAS) program is the development of a set of avionic architectural modules which will be applicable to the family of launch vehicles required to support the Advanced Launch System (ALS). To enable ALS cost/performance requirements to be met, the MPRAS must support autonomy, maintenance, and testability capabilities which exceed those present in conventional launch vehicles. The multi-path redundant or fault tolerance characteristics of the MPRAS are necessary to offset a reduction in avionics reliability due to the increased complexity needed to support these new cost reduction and performance capabilities and to meet avionics reliability requirements which will provide cost-effective reductions in overall ALS recurring costs. A complex, real-time distributed computing system is needed to meet the ALS avionics system requirements. General Dynamics, Boeing Aerospace, and C.S. Draper Laboratory have proposed system architectures as candidates for the ALS MPRAS. The purpose of this document is to report the results of independent performance and reliability characterization and assessment analyses of each proposed candidate architecture and qualitative assessments of testability, maintainability, and fault tolerance mechanisms. These independent analyses were conducted as part of the MPRAS Part 2 program and were carried under NASA Langley Research Contract NAS1-17964, Task Assignment 28.
The impact of photon flight path on S1 pulse shape analysis in liquid xenon two-phase detectors
NASA Astrophysics Data System (ADS)
Moongweluwan, M.
2016-02-01
The LUX dark matter search experiment is a 350 kg dual-phase xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. The success of two-phase xenon detectors for dark matter searches relies on their ability to distinguish electron recoil (ER) background events from nuclear recoil (NR) signal events. Typically, the NR-ER discrimination is obtained from the ratio of the electroluminescence light (S2) to the prompt scintillation light (S1). Analysis of the S1 pulse shape is an additional discrimination technique that can be used to distinguish NR from ER. Pulse-shape NR-ER discrimination can be achieved based on the ratio of the de-excitation processes from singlet and triplet states that generate the S1. The NR S1 is dominated by the de-excitation process from singlet states with a time constant of about 3 ns while the ER S1 is dominated by the de-excitation process from triplet states with a time constant of about 24 ns. As the size of the detectors increases, the variation in the S1 photon flight path can become comparable to these decay constants, reducing the utility of pulse-shape analysis to separate NR from ER. The effect of path length variations in the LUX detector has been studied using the results of simulations and the impact on the S1 pulse shape analysis is discussed.
NASA Astrophysics Data System (ADS)
Lathabai, Hiran H.; Prabhakaran, Thara; Changat, Manoj
2015-07-01
Biotechnology, ever since its inception has had a huge impact on the society and its various applications have been intricately woven into the human web of life. Its evolution amidst all the other research realms vital to mankind is remarkable. In this paper, we intend to identify the radical innovations in Biotechnology for Engineering using network analyses. Centrality analysis and Path analysis are used for identifying important works. Existence of Flow Vergence effect in the scientific literature is revealed. Flow Vergence gradient, an arc metric derived from FV model, is utilised for Path analysis which detects pivotal papers of paradigm shift more accurately. A major paradigm shift has been identified in the business models of Biotechnology for Engineering - 'Capability to Connectivity' model. Evidence towards the adoption of business practices in BT firms by nanotechnology start-ups is also identified. The notion of critical divergence is introduced and the exhibition of interdisciplinary interaction in emerging fields due to critical divergence is discussed. Implications of above analyses which target: (i) Science and technology policy makers, (ii) industrialists and investors, (iii) researchers in academia as well as industry, are also discussed.
Single molecule fluorescence experiments determine protein folding transition path times
Chung, Hoi Sung; McHale, Kevin; Louis, John M.; Eaton, William A.
2013-01-01
The transition path is the tiny fraction of an equilibrium molecular trajectory when a transition occurs by crossing the free-energy barrier between two states. It is a single-molecule property that contains all the mechanistic information on how a process occurs. As a step toward observing transition paths in protein folding we determined the average transition-path time for a fast- and a slow-folding protein from a photon-by-photon analysis of fluorescence trajectories in single-molecule Förster-resonance-energy-transfer experiments. While the folding rate coefficients differ by a factor of 10,000, the transition-path times differ by less than a factor of 5, showing that a fast-and a slow-folding protein take almost the same time to fold when folding actually happens. A very simple model based on energy landscape theory can explain this result. PMID:22363011
Exact Analysis of Squared Cross-Validity Coefficient in Predictive Regression Models
ERIC Educational Resources Information Center
Shieh, Gwowen
2009-01-01
In regression analysis, the notion of population validity is of theoretical interest for describing the usefulness of the underlying regression model, whereas the presumably more important concept of population cross-validity represents the predictive effectiveness for the regression equation in future research. It appears that the inference…
NASA Astrophysics Data System (ADS)
Zhou, Jianqin; Shen, Jun; Neill, W. Stuart
2016-07-01
A method of frequency analysis for the measurement of the temperature coefficient of refractive index (dn/dT) using a Fabry-Perot interferometer was developed and tested against ethanol and water. The temperature-dependent interferometric signal described by Airy's formula was analyzed in both the temperature and frequency domains. By fast Fourier transform, a low-pass filter was designed and employed to eliminate the noise superimposed on the signal. dn/dT was determined accurately from the noise-removed signal by peak analysis. Furthermore, the signal frequency parameters may be utilized for the material thermophysical property characterization. This method lays the foundation for an online dn/dT instrument for monitoring chemical processes.
Zhou, Jianqin; Shen, Jun; Neill, W Stuart
2016-07-01
A method of frequency analysis for the measurement of the temperature coefficient of refractive index (dn/dT) using a Fabry-Perot interferometer was developed and tested against ethanol and water. The temperature-dependent interferometric signal described by Airy's formula was analyzed in both the temperature and frequency domains. By fast Fourier transform, a low-pass filter was designed and employed to eliminate the noise superimposed on the signal. dn/dT was determined accurately from the noise-removed signal by peak analysis. Furthermore, the signal frequency parameters may be utilized for the material thermophysical property characterization. This method lays the foundation for an online dn/dT instrument for monitoring chemical processes. PMID:27475545
NASA Technical Reports Server (NTRS)
Powell, W. B.
1973-01-01
A methodology is described for the analysis of a transient temperature measurement made in a flat or curved plate subjected to convective heat transfer, such that the surface heat flux, the hot-gas temperture, and the gas heat transfer coefficient can be determined. It is shown that if the transient temperature measurement is made at a particular point located nearly midway in the thickness of the plate there is an important simplification in the data analysis process, in that the factor relating the surface heat flux to the measured rate of rise of temperature becomes invariant for a Fourier Number above 0.60 and for all values of the Biot Number. Parameters are derived, tabulated, and plotted which enable straightforward determination of the surface heat flux, the hot-gas temperature, of the plate, the rate of rise of temperature, the plate thickness and curvature, and the mean thermal properties of the plate material at the test temperature.
Point and path performance of light aircraft: A review and analysis
NASA Technical Reports Server (NTRS)
Smetana, F. O.; Summey, D. C.; Johnson, W. D.
1973-01-01
The literature on methods for predicting the performance of light aircraft is reviewed. The methods discussed in the review extend from the classical instantaneous maximum or minimum technique to techniques for generating mathematically optimum flight paths. Classical point performance techniques are shown to be adequate in many cases but their accuracies are compromised by the need to use simple lift, drag, and thrust relations in order to get closed form solutions. Also the investigation of the effect of changes in weight, altitude, configuration, etc. involves many essentially repetitive calculations. Accordingly, computer programs are provided which can fit arbitrary drag polars and power curves with very high precision and which can then use the resulting fits to compute the performance under the assumption that the aircraft is not accelerating.
Kudi: A free open-source python library for the analysis of properties along reaction paths.
Vogt-Geisse, Stefan
2016-05-01
With increasing computational capabilities, an ever growing amount of data is generated in computational chemistry that contains a vast amount of chemically relevant information. It is therefore imperative to create new computational tools in order to process and extract this data in a sensible way. Kudi is an open source library that aids in the extraction of chemical properties from reaction paths. The straightforward structure of Kudi makes it easy to use for users and allows for effortless implementation of new capabilities, and extension to any quantum chemistry package. A use case for Kudi is shown for the tautomerization reaction of formic acid. Kudi is available free of charge at www.github.com/stvogt/kudi. PMID:27107577
Graphical and Statistical Analysis of Airplane Passenger Cabin RF Coupling Paths to Avionics
NASA Technical Reports Server (NTRS)
Jafri, Madiha; Ely, Jay; Vahala, Linda
2003-01-01
Portable wireless technology provides many benefits to modern day travelers. Over the years however, numerous reports have cited portable electronic devices (PEDs) as a possible cause of electromagnetic interference (EMI) to aircraft navigation and communication radio systems. PEDs may act as transmitters, both intentional and unintentional, and their signals may be detected by the various radio receiver antennas installed on the aircraft. Measurement of the radiated field coupling between passenger cabin locations and aircraft communication and navigation receivers, via their antennas is defined herein as interference path loss (IPL). IPL data is required for assessing the threat of PEDs to aircraft radios, and is very dependent upon airplane size, the interfering transmitter position within the airplane, and the location of the particular antenna for the aircraft system of concern. NASA Langley Research Center, Eagles Wings Inc., and United Airlines personnel performed extensive IPL measurements on several Boeing 737 airplanes.
NASA Astrophysics Data System (ADS)
Moazen Ahmadi, Alireza; Howard, Carl Q.; Petersen, Dick
2016-03-01
This paper describes the experimental investigation of the vibration signature generated by rolling elements entering and exiting a notch defect in the outer raceway of a bearing. The vibration responses of the bearing housing and the displacement between the raceways were measured and analyzed. These key features can be used to estimate the size of the defect and is demonstrated in this paper for a range of shaft speeds and bearing loads. It is shown that existing defect size estimation methods include assumptions that describe the path of the rolling elements in the defect zone leading to poor estimates of defect size. A new defect size estimation method is proposed and is shown to be accurate for estimating a range of notch defect geometries over a range of shaft speeds and applied loads.
Gholamnia Shirvani, Zeinab; Ghofranipour, Fazlollah; Gharakhanlou, Reza; Kazemnejad, Anoshirvan
2015-01-01
Level of physical activity as a key determinant of healthy lifestyle less than is required in individuals particularly women. Applying theories of behavioral change about complex behaviors such as physical activity leads to identify effective factors and their relations. The aim of this study was to determine predictors of physical activity behavior based on the Theory of Planned Behavior in military staff's wives in Tehran. This cross-sectional study was performed in 180 military personnel's spouses residing in organizational houses, in Tehran, Iran in 2014. The participants were randomly selected with multi-stage cluster sampling. The validity and reliability of the theory based scale evaluated before conducting the path analysis. Statistical analysis was carried out using SPSS16 and LISREL8.8. The results indicated the model explained 77% and 17% of intention and behavior variance. Subjective norms (Beta=0.83) and intention (Beta=0.37) were the strongest predictors of intention and behavior, respectively. The instrumental and affective attitude had no significant path to intention and behavior. The direct relation of perceived behavioral control to behavior was non-significant. This research demonstrated relative importance and relationships of Theory of Planned Behavior constructs in physical activity behavior of military personnel's spouses in Tehran. It is essential to consider these determinants in designing of educational interventions for promoting and maintaining physical activity behavior in this target group. PMID:25948459
Shuang, Bo; Byers, Chad P.; Kisley, Lydia; Wang, Lin-Yung; Zhao, Julia; Morimura, Hiroyuki; Link, Stephan; Landes, Christy F.
2013-01-01
Two Maximum Likelihood Estimation (MLE) methods were developed for optimizing the analysis of single-molecule trajectories that include phenomena such as experimental noise, photoblinking, photobleaching, and translation or rotation out of the collection plane. In particular, short, single-molecule trajectories with photoblinking were studied, and our method was compared with existing analytical techniques applied to simulated data. The optimal method for various experimental cases was established, and the optimized MLE method was applied to a real experimental system: single-molecule diffusion of fluorescent molecular machines known as nanocars. PMID:23215347
Kim, Jong Kyung; Chang, Sun Ju
2015-08-01
The purpose of this study was to examine the relationship between attitudes toward their organizations and voluntary turnover intention among South Korean clinical nurses. Data from a total of 312 clinical nurses in six hospitals in South Korea were collected for the study. Both hierarchical multiple regression analysis and path analysis were used to analyse the data. The overall fit of the hypothetical model was good. Voluntary turnover intention was found to have significant direct pathways to job embeddedness and organizational commitment. Organizational commitment and satisfaction with organizational rewards had indirect pathways to voluntary turnover intention through job embeddedness. All variances explained 62.3% of the voluntary turnover intention scores. The findings suggest that greater job embeddedness, organizational commitment and satisfaction with organizational rewards lead to lower voluntary turnover intention among clinical nurses in South Korea. PMID:24666586
Analysis of ligand-protein exchange by Clustering of Ligand Diffusion Coefficient Pairs (CoLD-CoP)
NASA Astrophysics Data System (ADS)
Snyder, David A.; Chantova, Mihaela; Chaudhry, Saadia
2015-06-01
NMR spectroscopy is a powerful tool in describing protein structures and protein activity for pharmaceutical and biochemical development. This study describes a method to determine weak binding ligands in biological systems by using hierarchic diffusion coefficient clustering of multidimensional data obtained with a 400 MHz Bruker NMR. Comparison of DOSY spectrums of ligands of the chemical library in the presence and absence of target proteins show translational diffusion rates for small molecules upon interaction with macromolecules. For weak binders such as compounds found in fragment libraries, changes in diffusion rates upon macromolecular binding are on the order of the precision of DOSY diffusion measurements, and identifying such subtle shifts in diffusion requires careful statistical analysis. The "CoLD-CoP" (Clustering of Ligand Diffusion Coefficient Pairs) method presented here uses SAHN clustering to identify protein-binders in a chemical library or even a not fully characterized metabolite mixture. We will show how DOSY NMR and the "CoLD-CoP" method complement each other in identifying the most suitable candidates for lysozyme and wheat germ acid phosphatase.
Santos, A. dos; Fuga, R.; Abe, A.Y.
2005-10-15
TORT, an S{sub N} three-dimensional transport code, is employed for the analysis of the inversion point of the isothermal reactivity coefficient of the IPEN/MB-01 reactor. The analyses are performed in companion NJOY, AMPX-II, and TORT systems considering the data libraries ENDF/B-VI.8, JENDL3.3, and JEF3.0. The analyses reveal that for this peculiar problem, there is a need to convert all the computer codes to DOUBLE-PRECISION as well as to increase to seven the number of digits of the ANISN library generated by XSDRNPM. Contrary to the traditional diffusion theory codes, TORT k{sub eff} results are very sensitive to the number of both fine and broad groups. For instance, the traditional and very well known two- and four-group structure, largely utilized in several diffusion codes, produced simply unacceptable k{sub eff} results. The highest deviation between calculated and experimental values found for the inversion point was -4.48 deg. C. At first glance, there appears to be a significant discrepancy. However, in terms of reactivity coefficient, this discrepancy means a deviation of -0.90 {+-} 0.05 pcm/deg. C, which indicates that the calculational methodology and related nuclear data libraries meet the desired accuracy (-1.0 pcm/deg. C) for the determination of this parameter for thermal reactors.
NASA Technical Reports Server (NTRS)
Cohen, S. C.
1980-01-01
A technique for fitting a straight line to a collection of data points is given. The relationships between the slopes and correlation coefficients, and between the corresponding standard deviations and correlation coefficient are given.
Fu, Dong-Jing; Bossie, Cynthia A.; Alphs, Larry
2015-01-01
Background: This analysis evaluates improvement in symptoms of depression in patients with schizoaffective disorder administered oral paliperidone extended-release by accounting for the magnitude of direct and indirect (changes in negative and positive symptoms and worsening of extrapyramidal symptoms) treatment effects on depressive symptoms. Methods: Data for this post hoc analysis were drawn from two six-week, randomized, placebo-controlled studies of paliperidone extended-release versus placebo in adult subjects with schizoaffective disorder (N=614; NCT00412373, NCT00397033). Subjects with baseline 17-item Hamilton Rating Scale for Depression scores of 16 or greater were included. Structural equation models (path analyses) were used to separate total effects into direct and indirect effects on depressive symptoms. Change from baseline in 17-item Hamilton Rating Scale for Depression score at the Week 6 end point was the dependent variable; changes in Positive and Negative Syndrome Scale positive and negative factors and Simpson-Angus Scale (to evaluate extrapyramidal symptoms) scores were independent variables. Results: At baseline, 332 of 614 (54.1%) subjects had a 17-item Hamilton Rating Scale for Depression score of 16 or greater. Path analysis determined that up to 26.4 percent of the paliperidone extended-release versus placebo effect on depressive symptoms may be attributed to a direct treatment effect, and 45.8 percent and 28.4 percent were mediated indirectly through improvements on positive and negative symptoms, respectively. No effects were identified as mediated through extrapyramidal symptoms changes (-0.7%). Conclusion: Results of this analysis suggest that paliperidone’s effect on depressive symptoms in subjects with schizoaffective disorder participating in two six-week, randomized, placebo-controlled studies is mediated through indirect effects (e.g., positive and negative symptom changes) and a direct treatment effect. PMID:27222760
Bayesian Uncertainty Quantification for Bond Energies and Mobilities Using Path Integral Analysis
Chang, Joshua C.; Fok, Pak-Wing; Chou, Tom
2015-01-01
Dynamic single-molecule force spectroscopy is often used to distort bonds. The resulting responses, in the form of rupture forces, work applied, and trajectories of displacements, are used to reconstruct bond potentials. Such approaches often rely on simple parameterizations of one-dimensional bond potentials, assumptions on equilibrium starting states, and/or large amounts of trajectory data. Parametric approaches typically fail at inferring complicated bond potentials with multiple minima, while piecewise estimation may not guarantee smooth results with the appropriate behavior at large distances. Existing techniques, particularly those based on work theorems, also do not address spatial variations in the diffusivity that may arise from spatially inhomogeneous coupling to other degrees of freedom in the macromolecule. To address these challenges, we develop a comprehensive empirical Bayesian approach that incorporates data and regularization terms directly into a path integral. All experimental and statistical parameters in our method are estimated directly from the data. Upon testing our method on simulated data, our regularized approach requires less data and allows simultaneous inference of both complex bond potentials and diffusivity profiles. Crucially, we show that the accuracy of the reconstructed bond potential is sensitive to the spatially varying diffusivity and accurate reconstruction can be expected only when both are simultaneously inferred. Moreover, after providing a means for self-consistently choosing regularization parameters from data, we derive posterior probability distributions, allowing for uncertainty quantification. PMID:26331254
NASA Technical Reports Server (NTRS)
James, R.; Brownlow, J. D.
1985-01-01
A study is performed under NASA contract to evaluate data from an AN/FPS-16 radar installed for support of flight programs at Dryden Flight Research Facility of NASA Ames Research Center. The purpose of this study is to provide information necessary for improving post-flight data reduction and knowledge of accuracy of derived radar quantities. Tracking data from six flights are analyzed. Noise and bias errors in raw tracking data are determined for each of the flights. A discussion of an altitude bias error during all of the tracking missions is included. This bias error is defined by utilizing pressure altitude measurements made during survey flights. Four separate filtering methods, representative of the most widely used optimal estimation techniques for enhancement of radar tracking data, are analyzed for suitability in processing both real-time and post-mission data. Additional information regarding the radar and its measurements, including typical noise and bias errors in the range and angle measurements, is also presented. This report is in two parts. This is part 2, a discussion of the modeling of propagation path errors.
Roohafza, Hamidreza; Feizi, Awat; Afshar, Hamid; Mazaheri, Mina; Behnamfar, Omid; Hassanzadeh-Keshteli, Ammar; Adibi, Peyman
2016-01-01
AIM: To provide a structural model of the relationship between personality traits, perceived stress, coping strategies, social support, and psychological outcomes in the general population. METHODS: This is a cross sectional study in which the study group was selected using multistage cluster and convenience sampling among a population of 4 million. For data collection, a total of 4763 individuals were asked to complete a questionnaire on demographics, personality traits, life events, coping with stress, social support, and psychological outcomes such as anxiety and depression. To evaluate the comprehensive relationship between the variables, a path model was fitted. RESULTS: The standard electronic modules showed that personality traits and perceived stress are important determinants of psychological outcomes. Social support and coping strategies were demonstrated to reduce the increasing cumulative positive effects of neuroticism and perceived stress on the psychological outcomes and enhance the protective effect of extraversion through decreasing the positive effect of perceived stress on the psychological outcomes. CONCLUSION: Personal resources play an important role in reduction and prevention of anxiety and depression. In order to improve the psychological health, it is necessary to train and reinforce the adaptive coping strategies and social support, and thus, to moderate negative personality traits. PMID:27354968
NASA Astrophysics Data System (ADS)
Kubota, C.; Kawanami, O.; Asada, Y.; Wada, Y.; Nagayasu, T.; Shinmoto, Y.; Ohta, H.; Kabov, O.; Queeckers, P.; Chikov, S.; Straub, J.
2011-12-01
Investigation of mechanisms in nucleate boiling under microgravity conditions is essential for the development of the cooling systems handling a large amount of waste heat. A transparent heating surface with multiple arrays of 88 thin film temperature sensors and mini-heaters was developed for the clarification of boiling heat transfer mechanisms in microgravity. To investigate gravity effects on the microlayer behaviors and corresponding local heat transfer coefficients, images of liquid-vapor behaviors underneath attached bubbles and local heat transfer data were simultaneously obtained in microgravity pool boiling. The present paper reports the analysis of the data measured during the ESA parabolic flight campaign. It was found that the liquid-vapor behaviors were strongly affected by the direction and the level of residual gravity. Various patterns of liquid-vapor behaviours and corresponding enhancement or deterioration of the heat transfer are observed.
Lu, Z. Q. J.; Lowhorn, N. D.; Wong-Ng, W.; Zhang, W.; Thomas, E. L.; Otani, M.; Green, M. L.; Tran, T. N.; Caylor, C.; Dilley, N. R.; Downey, A.; Edwards, B.; Elsner, N.; Ghamaty, S.; Hogan, T.; Jie, Q.; Li, Q.; Martin, J.; Nolas, G.; Obara, H.; Sharp, J.; Venkatasubramanian, R.; Willigan, R.; Yang, J.; Tritt, T.
2009-01-01
In an effort to develop a Standard Reference Material (SRM™) for Seebeck coefficient, we have conducted a round-robin measurement survey of two candidate materials—undoped Bi2Te3 and Constantan (55 % Cu and 45 % Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of different commercial and custom-built measurement systems and techniques. In this paper we report the detailed statistical analyses on the interlaboratory measurement results and the statistical methodology for analysis of irregularly sampled measurement curves in the interlaboratory study setting. Based on these results, we have selected Bi2Te3 as the prototype standard material. Once available, this SRM will be useful for future interlaboratory data comparison and instrument calibrations.
Zhao, Renjie; Evans, James W.; Oliveira, Tiago J.
2016-04-08
Here, a discrete version of deposition-diffusion equations appropriate for description of step flow on a vicinal surface is analyzed for a two-dimensional grid of adsorption sites representing the stepped surface and explicitly incorporating kinks along the step edges. Model energetics and kinetics appropriately account for binding of adatoms at steps and kinks, distinct terrace and edge diffusion rates, and possible additional barriers for attachment to steps. Analysis of adatom attachment fluxes as well as limiting values of adatom densities at step edges for nonuniform deposition scenarios allows determination of both permeability and kinetic coefficients. Behavior of these quantities is assessedmore » as a function of key system parameters including kink density, step attachment barriers, and the step edge diffusion rate.« less
NASA Astrophysics Data System (ADS)
Bekstein, A.; de Urquijo, J.; Ducasse, O.; Rodríguez-Luna, J. C.; Juárez, A. M.
2012-06-01
We present in this paper the interpretation and analysis of transient pulses from a pulsed Townsend experiment by solving the continuity equations of the charged carriers (electrons and ions) involved in the avalanche. The set of second order partial differential equations is solved by SIMAV, a simulator designed specifically for the pulsed Townsend avalanche. Complex situations involving processes such as electron detachment, ion-molecule reactions, Penning ionization and secondary electron emission from ion impact at the cathode, virtually impossible to solve analytically, are discussed here to illustrate the capability of the simulator to help explain the various reaction processes involved in the avalanche, and also to derive some of the transport and reaction coefficients.
One-Sided Measurement Approach on Ultrasonic Beam Path Analysis in CFRP Composite Laminates
NASA Astrophysics Data System (ADS)
Im, K. H.; Hsu, D. K.; Kim, H. J.; Song, S. J.; Dayal, V.; Barnard, D.; Park, J. W.; Lee, K. S.; Yang, Y. J.; Yang, I. Y.
2008-02-01
Composite materials are attractive for a wide range of applications because of high performance engineering structures. In particular, the importance of carbon-fiber reinforced plastics (CFRP) has been generally recognized in both space and civil aircraft industries; so, CFRP composite laminates are widely used. It is very important to detect defects in composite laminates because they cause the mechanical properties (stiffness, strength) of the laminate to be reduced. As well known for ultrasonic technique for evaluating the defect of CFRP composite laminates, a pitch-catch technique was found to be more practical than normal incidence backwall echo of longitudinal wave to arbitrary flaws in the composite, including fiber orientation, low level porosity, ply waviness, and cracks. The measurement depth using Rayleigh probes can be increased by increasing the separation distance of the transmitting and receiving probes. Also, with the aid of the automatic scanner, the one-sided pitch-catch probe was used to produce C-scan images for mapping out the images with beam profiles. Especially pitch-catch beam path was nondestructively characterized for the specimens when measuring a peak-to-peak amplitude and time-of-flight in order to build the beam profile modeling in the unidirectional CFRP composite laminates. Also, the pitch-catch simulation was performed to predict the beam profile trend of wave propagation in the unidirectional CF/Epoxy composite laminates. Therefore, it is found that the experimentally Rayleigh wave variation of pitch-catch ultrasonic signal was consistent with simulated results and one-side ultrasonic measurement might be very useful to detect the defects in CFRP composites.
NASA Astrophysics Data System (ADS)
Ivanov, A.; Voynikova, D.; Gocheva-Ilieva, S.; Kulina, H.; Iliev, I.
2015-10-01
The monitoring and control of air quality in urban areas is important problem in many European countries. The main air pollutants are observed and a huge amount of data is collected during the last years. In Bulgaria, the air quality is surveyed by the official environmental agency and in many towns exceedances of harmful pollutants are detected. The aim of this study is to investigate the pollution from 9 air pollutants in the town of Dimitrovgrad, Bulgaria in the period of 5 years based on hourly data. Principal Component Analysis (PCA) is used to discover the patterns in the overall pollution and the contribution of the 9 pollutants. In addition the Generalized Path Seeker (GPS) regularized regression method is applied to find dependence of CO (carbon monoxide) with respect to other pollutants and 8 meteorological parameters. It is reported that the CO concentrations are in continuously repeated low level quantities very harmful for human health.
Daghestani, Nart S; Brownsword, Richard; Weidmann, Damien
2014-12-15
Atmospheric methane concentration levels were detected using a custom built laser dispersion spectrometer in a long open-path beam configuration. The instrument is driven by a chirped distributed feedback mid-infrared quantum cascade laser centered at ~1283.46 cm^{-1} and covers intense rotational-vibrational transitions from the fundamental ν_{4} band of methane. A full forward model simulating molecular absorption and dispersion profiles, as well as instrumental noise, is demonstrated. The instrument's analytical model is validated and used for quantitative instrumental optimization. The temporal evolution of atmospheric methane mixing ratios is retrieved using a fitting algorithm based on the model. Full error propagation analysis on precision gives a normalized sensitivity of ~3 ppm.m.Hz^{-0.5} for atmospheric methane. PMID:25607487
Daigle, Hugh; Rice, Mary Anna; Daigle, Hugh
2015-12-14
Relative permeabilities to water and gas are important parameters for accurate modeling of the formation of methane hydrate deposits and production of methane from hydrate reservoirs. Experimental measurements of gas and water permeability in the presence of hydrate are difficult to obtain. The few datasets that do exist suggest that relative permeability obeys a power law relationship with water or gas saturation with exponents ranging from around 2 to greater than 10. Critical path analysis and percolation theory provide a framework for interpreting the saturation-dependence of relative permeability based on percolation thresholds and the breadth of pore size distributions, which may be determined easily from 3-D images or gas adsorption-desorption hysteresis. We show that the exponent of the permeability-saturation relationship for relative permeability to water is related to the breadth of the pore size distribution, with broader pore size distributions corresponding to larger exponents. Relative permeability to water in well-sorted sediments with narrow pore size distributions, such as Berea sandstone or Toyoura sand, follows percolation scaling with an exponent of 2. On the other hand, pore-size distributions determined from argon adsorption measurements we performed on clays from the Nankai Trough suggest that relative permeability to water in fine-grained intervals may be characterized by exponents as large as 10 as determined from critical path analysis. We also show that relative permeability to the gas phase follows percolation scaling with a quadratic dependence on gas saturation, but the threshold gas saturation for percolation changes with hydrate saturation, which is an important consideration in systems in which both hydrate and gas are present, such as during production from a hydrate reservoir. Our work shows how measurements of pore size distributions from 3-D imaging or gas adsorption may be used to determine relative permeabilities.
Patnaik, Pratap R
2008-01-01
Background Although the production of poly-β-hydroxybutyrate (PHB) has many biological, energetic and environmental advantages over chemically synthesized polymers, synthetic polymers continue to be produced industrially since the productivities of fermentation processes fr PHB are not yet economically competitive. Improvement of a PHB fermentation requires good understanding and optimization under the realistic conditions of large bioreactors. Laboratory-scale studies have shown that co-cultures of Ralstonia eutropha and Lactobacillus delbrueckii generate better fermentation efficiencies than R. eutropha alone. In large bioreactors, incomplete dispersioin and perturbations in the dissolved oxygen (DO) concentration, both of which affect the fermentation, have to be considered. This study analyzes the effect of DO fluctuations on bioreactor performance for both ideal and optimally dispersed broths. Results Response coefficient analysis was employed to obtain quantitative information on the effect of DO perturbations on different variables. Three values of the Peclet number (Pe) cheracterized three levels of dispersion: Pe = 0.01 for nearly complete dispersion, Pe = 20 for optimum dispersion and Pe = 60 for insufficient dispersion. The response coefficients (RCs) of the pairs of bacterial concentrations and the main substrates, glucose and ammonium chloride, showed contrasting variations with time. Lactate, a critical intermediate, and PHB had similar RC profiles but those of lactate were one to two orders of magnitude larger than other RCs. Significantly, the optimum Pe also resulted in the largest RCs, suggesting a balance between productivity and reactor stability. Conclusion Since R. eutropha requires oxygen for its growth whereas L. delbrueckii does not, fluctuations in the DO concentartion have a strong influence on the fermentation. Apart from this, the mechanism of PHB biosynthesis indicates that control of lactate is a critical determinant of fermentation
NASA Astrophysics Data System (ADS)
Thompson, Sarah Ann; Sydeman, William J.; Santora, Jarrod A.; Black, Bryan A.; Suryan, Robert M.; Calambokidis, John; Peterson, William T.; Bograd, Steven J.
2012-08-01
Upwelling in eastern boundary current systems is a primary driver of ecosystem productivity. Typically, peak upwelling occurs during spring and summer, but winter upwelling may also be important to ecosystem functions. In this study, we investigated the hypothesis that winter and spring/summer upwelling, operating through indirect trophic interactions, are important to a suite of top predators in the California Current. To test this hypothesis, we collated information on upwelling, chlorophyll-a concentrations, zooplankton and forage fish, and related these to predator responses including rockfish growth, salmon abundance, seabird productivity and phenology (timing of egg-laying), and whale abundance. Seabird diets served in part as food web indicators. We modeled pathways of response using path analysis and tested for significance of the dominant paths with multiple regression. We found support for the hypothesis that relationships between upwelling and top predator variables were mediated primarily by intermediate trophic levels. Both winter and summer upwelling were important in path models, as were intermediate lower and mid trophic level functional groups represented by chlorophyll-a, zooplankton, and forage fish. Significant pathways of response explained from 50% to 80% of the variation of seabird (Cassin's auklet (Ptychoramphus aleuticus) and common murre (Uria aalge)), humpback whale (Megaptera novaeangliae) and Chinook salmon (Oncorhynchus tshawytscha) dependent variables, whereas splitnose rockfish (Sebastes diploproa) showed no significant response pathways. Upwelling and trophic responses for salmon were established for both the year of ocean entry and the year of return, with zooplankton important in the year of ocean entry and forage fish important in the year of return. This study provides one of the first comparative investigations between upwelling and predators, from fish to marine mammals and birds within a geographically restricted area
ERIC Educational Resources Information Center
Brown, Steven D.; Tramayne, Selena; Hoxha, Denada; Telander, Kyle; Fan, Xiaoyan; Lent, Robert W.
2008-01-01
This study tested Social Cognitive Career Theory's (SCCT) academic performance model using a two-stage approach that combined meta-analytic and structural equation modeling methodologies. Unbiased correlations obtained from a previously published meta-analysis [Robbins, S. B., Lauver, K., Le, H., Davis, D., & Langley, R. (2004). Do psychosocial…
ERIC Educational Resources Information Center
Cooks, Leda; Descutner, David
1993-01-01
Uses a dramatistic analysis to examine the rhetorical elements of two therapeutic discourses designed to help women cope with eating disorders: spiritual recovery therapy (SR) and feminist psychoanalytic therapy (FT). Finds each therapy has the same key terms but serve different functions and encourage different interpretations. (NH)
ERIC Educational Resources Information Center
Martin, James L.
This paper reports on attempts by the author to construct a theoretical framework of adult education participation using a theory development process and the corresponding multivariate statistical techniques. Two problems are identified: the lack of theoretical framework in studying problems, and the limiting of statistical analysis to univariate…
Performance analysis of a PM motor by changing the magnitude and the path of flux
NASA Astrophysics Data System (ADS)
Lee, Hyung-Woo; Lee, Ki-Doek; Kim, Mi-Jung; Lee, Jae-Jun; Han, Jung-Ho; Jeong, Tae-Chul; Lee, Ho-Joon; Ryu, Gwang-Hyeon; Park, Hyun-Jong; Lee, Ju
2013-01-01
In an electric motor in which permanent magnets are used, the magnetic flux is caused by the magneto-motive force of the permanent magnets of the rotor and the stator winding wire, and the performance of the electric motor is determined by the scale of the magnetic flux and the magnetic circuit. This thesis is aimed at introducing electric motors in which permanent magnets are used and focuses on a performance analysis of said electric motors according to the scale of the magnetic flux and changes in the magnetic circuit. The analysis was carried out by separating the magnetic flux occurring at the stator winding wire into the magnetic flux of axis d and that of q axis, so that the impact of the magnetic flux on the performance of the electric motor could be analyzed. In addition, the impact of changes in the magnetic circuit, which were caused by the magnetic flux at the permanent magnet of the rotator, on the electric motor was analyzed. Finally, the results of the analysis were verified by performing experiments on a model made by using selected analysis results.
Technology Transfer Automated Retrieval System (TEKTRAN)
Critical path analysis (CPA) is a method for estimating macroscopic transport coefficients of heterogeneous materials that are highly disordered at the micro-scale. Developed originally to model conduction in semiconductors, numerous researchers have noted that CPA might also have relevance to flow ...
Kumar, Birendra; Mali, Himanshi; Gupta, Ekta
2014-01-01
Menthofuran rich eight half-sib seed progeny of Mentha piperita (MPS-36) were studied for various genetic parameters, namely, coefficient of variation, heritability, genetic advance, correlation, and path of various plant and oil attributes, namely, plant height, L:S ratio, herb yield, β -myrcene, limonene, 1,8-cineole, menthone, menthofuran, neomenthone, pulegone, and menthol. Maximum genotypic coefficient of variation and genetic advance as percentage of mean were recorded for pulegone, followed by menthofuran and 1,8-cineole. The genotypic correlation in general was higher than phenotypic; positive significant correlation was recorded for limonene with 1,8-cineole and menthone, β -myrcene with limonene, and 1,8-cineole and menthofuran with neomenthol. A high direct positive effect on menthofuran was of neomenthol. PMID:24963471
Kumar, Birendra; Mali, Himanshi; Gupta, Ekta
2014-01-01
Menthofuran rich eight half-sib seed progeny of Mentha piperita (MPS-36) were studied for various genetic parameters, namely, coefficient of variation, heritability, genetic advance, correlation, and path of various plant and oil attributes, namely, plant height, L : S ratio, herb yield, β-myrcene, limonene, 1,8-cineole, menthone, menthofuran, neomenthone, pulegone, and menthol. Maximum genotypic coefficient of variation and genetic advance as percentage of mean were recorded for pulegone, followed by menthofuran and 1,8-cineole. The genotypic correlation in general was higher than phenotypic; positive significant correlation was recorded for limonene with 1,8-cineole and menthone, β-myrcene with limonene, and 1,8-cineole and menthofuran with neomenthol. A high direct positive effect on menthofuran was of neomenthol. PMID:24963471
NASA Astrophysics Data System (ADS)
Coker, Omotola
Thermal barrier coatings (TBCs) are highly sophisticated micro scale ceramic insulation applied on high temperature components such as gas turbine blades. TBCs create a large temperature drop between the gas turbine environment and the underlying metal blades. TBC lifetime is finite and influenced by several factors such as: Bond Coat (BC) oxidation, BC roughness, Coefficient of thermal expansion (CTE) mismatch between the layers, and creep properties of the TBC system. However, there is a lack of reliable methods of TBC life prediction which result in under utilization of these coatings. This research study focuses on modeling the steady state thermal stresses in TBC systems of various oxide thicknesses, and BC roughness, using Finite Element Analysis (FEA). The model factors into it the temperature dependent thermo mechanical properties of each layer, as well as the creep properties. The steady state model results show similar results to the existing transient models: an increase in tensile stresses as the oxide thickness increases, an increase in tensile stresses with BC roughness and stress relaxation in the ceramic BC interface due to creep. It also shows in each model, initially compressive stresses in the BC - Top Coat (TC) interface, and its evolution into higher tensile stresses which lead to crack formation and ultimately failure of the TBC by spallation.
Huang, Da Wei; Sherman, Brad T.; Lempicki, Richard A.
2009-01-01
Functional analysis of large gene lists, derived in most cases from emerging high-throughput genomic, proteomic and bioinformatics scanning approaches, is still a challenging and daunting task. The gene-annotation enrichment analysis is a promising high-throughput strategy that increases the likelihood for investigators to identify biological processes most pertinent to their study. Approximately 68 bioinformatics enrichment tools that are currently available in the community are collected in this survey. Tools are uniquely categorized into three major classes, according to their underlying enrichment algorithms. The comprehensive collections, unique tool classifications and associated questions/issues will provide a more comprehensive and up-to-date view regarding the advantages, pitfalls and recent trends in a simpler tool-class level rather than by a tool-by-tool approach. Thus, the survey will help tool designers/developers and experienced end users understand the underlying algorithms and pertinent details of particular tool categories/tools, enabling them to make the best choices for their particular research interests. PMID:19033363
West, Aaron C; Schmidt, Michael W; Gordon, Mark S; Ruedenberg, Klaus
2015-10-15
The quantitative analysis of molecular density matrices in terms of oriented quasi-atomic orbitals (QUAOs) is shown to yield detailed conceptual insight into the dissociation of dioxetane on the basis of ab initio wave functions. The QUAOs persist and can be followed throughout the reaction path. The kinetic bond orders and the orbital populations of the QUAOs quantitatively reveal the changes of the bonding interactions along the reaction path. At the transition state the OO bond is broken, and the molecule becomes a biradical. After the transition state the reaction path bifurcates. The minimum energy path gently descends from the transition state via a valley-ridge inflection point to a second saddle point, from which two new minimum energy paths lead to two equivalent formaldehyde dimers. The CC bond breaks, and the π-bonds of the formaldehyde fragments form in close vicinity of the second saddle point. The changes of the interactions in this region are elucidated by the analysis of the rearrangements of the QUAOs. PMID:26371996
NASA Astrophysics Data System (ADS)
Rukhovich, D. I.; Rukhovich, A. D.; Rukhovich, D. D.; Simakova, M. S.; Kulyanitsa, A. L.; Bryzzhev, A. V.; Koroleva, P. V.
2016-08-01
The coefficients of the soil line are often taken into account in calculations of vegetation indices. These coefficients are usually calculated for the entire satellite image, or are taken as constants without any calculations. In both cases, the informativeness of these coefficients is low and insufficient for the needs of soil mapping. In our study, we calculated soil line coefficients at 8000 lattice points for the territory of Plavsk, Arsen'evsk, and Chern districts of Tula oblast on the basis of 34 Landsat 5, 7, and 8 images obtained in 1985-2014. In order to distinguish between the soil line calculated for a given image and the soil line calculated for lattice points on the basis of dozens of multitemporal images, we suggest that the latter can be referred to as the temporal soil line. The temporal soil line is described by a classical equation: NIR = RED a + b, where a is its slope relative to the horizontal axis (RED), and b is the Y-axis (NIR) intercept. Both coefficients were used to create soil maps. The verification of the maps was performed with the use of data on 1985 soil pits. The informativeness of these coefficients appeared to be sufficient for delineation of eight groups of soils of different taxonomic levels: soddy moderately podzolic soils, soddy slightly podzolic soils, soddy-podzolic soils, light gray forest soils, gray forest soils, dark gray forest soils, podzolized chernozems, and leached chernozems. The b coefficient proved to be more informative, as it allowed us to create the soil map precisely on its basis. In order to create the soil map on the basis of the a coefficient, we had to apply some threshold values of the b coefficient. The bare soil on each of Landsat scenes was separated with the help of the mask of agricultural fields and the notion of the spectral neighborhood of soil line (SNSL).
Singh, Abanish; Babyak, Michael A; Nolan, Daniel K; Brummett, Beverly H; Jiang, Rong; Siegler, Ilene C; Kraus, William E; Shah, Svati H; Williams, Redford B; Hauser, Elizabeth R
2015-06-01
We performed gene-environment interaction genome-wide association analysis (G × E GWAS) to identify SNPs whose effects on metabolic traits are modified by chronic psychosocial stress in the Multi-Ethnic Study of Atherosclerosis (MESA). In Whites, the G × E GWAS for hip circumference identified five SNPs within the Early B-cell Factor 1 (EBF1) gene, all of which were in strong linkage disequilibrium. The gene-by-stress interaction (SNP × STRESS) term P-values were genome-wide significant (Ps = 7.14E-09 to 2.33E-08, uncorrected; Ps = 1.99E-07 to 5.18E-07, corrected for genomic control). The SNP-only (without interaction) model P-values (Ps = 0.011-0.022) were not significant at the conventional genome-wide significance level. Further analysis of related phenotypes identified gene-by-stress interaction effects for waist circumference, body mass index (BMI), fasting glucose, type II diabetes status, and common carotid intimal-medial thickness (CCIMT), supporting a proposed model of gene-by-stress interaction that connects cardiovascular disease (CVD) risk factor endophenotypes such as central obesity and increased blood glucose or diabetes to CVD itself. Structural equation path analysis suggested that the path from chronic psychosocial stress to CCIMT via hip circumference and fasting glucose was larger (estimate = 0.26, P = 0.033, 95% CI = 0.02-0.49) in the EBF1 rs4704963 CT/CC genotypes group than the same path in the TT group (estimate = 0.004, P = 0.34, 95% CI = -0.004-0.012). We replicated the association of the EBF1 SNPs and hip circumference in the Framingham Offspring Cohort (gene-by-stress term P-values = 0.007-0.012) as well as identified similar path relationships. This observed and replicated interaction between psychosocial stress and variation in the EBF1 gene may provide a biological hypothesis for the complex relationship between psychosocial stress, central obesity, diabetes, and cardiovascular disease. PMID:25271088
Kheirollahpour, Maryam; Shohaimi, Shamarina
2014-01-01
The main objective of this study is to identify and develop a comprehensive model which estimates and evaluates the overall relations among the factors that lead to weight gain in children by using structural equation modeling. The proposed models in this study explore the connection among the socioeconomic status of the family, parental feeding practice, and physical activity. Six structural models were tested to identify the direct and indirect relationship between the socioeconomic status and parental feeding practice general level of physical activity, and weight status of children. Finally, a comprehensive model was devised to show how these factors relate to each other as well as to the body mass index (BMI) of the children simultaneously. Concerning the methodology of the current study, confirmatory factor analysis (CFA) was applied to reveal the hidden (secondary) effect of socioeconomic factors on feeding practice and ultimately on the weight status of the children and also to determine the degree of model fit. The comprehensive structural model tested in this study suggested that there are significant direct and indirect relationships among variables of interest. Moreover, the results suggest that parental feeding practice and physical activity are mediators in the structural model. PMID:25097878
Linear and nonlinear dynamic analysis of redundant load path bearingless rotor systems
NASA Technical Reports Server (NTRS)
Murthy, V. R.; Shultz, Louis A.
1994-01-01
The goal of this research is to develop the transfer matrix method to treat nonlinear autonomous boundary value problems with multiple branches. The application is the complete nonlinear aeroelastic analysis of multiple-branched rotor blades. Once the development is complete, it can be incorporated into the existing transfer matrix analyses. There are several difficulties to be overcome in reaching this objective. The conventional transfer matrix method is limited in that it is applicable only to linear branch chain-like structures, but consideration of multiple branch modeling is important for bearingless rotors. Also, hingeless and bearingless rotor blade dynamic characteristics (particularly their aeroelasticity problems) are inherently nonlinear. The nonlinear equations of motion and the multiple-branched boundary value problem are treated together using a direct transfer matrix method. First, the formulation is applied to a nonlinear single-branch blade to validate the nonlinear portion of the formulation. The nonlinear system of equations is iteratively solved using a form of Newton-Raphson iteration scheme developed for differential equations of continuous systems. The formulation is then applied to determine the nonlinear steady state trim and aeroelastic stability of a rotor blade in hover with two branches at the root. A comprehensive computer program is developed and is used to obtain numerical results for the (1) free vibration, (2) nonlinearly deformed steady state, (3) free vibration about the nonlinearly deformed steady state, and (4) aeroelastic stability tasks. The numerical results obtained by the present method agree with results from other methods.
Thermal stress analysis of ceramic gas-path seal components for aircraft turbines
NASA Technical Reports Server (NTRS)
Kennedy, F. E.; Bill, R. C.
1979-01-01
Stress and temperature distributions were evaluated numerically for a blade-tip seal system proposed for gas turbine applications. The seal consists of an abradable ceramic layer on metallic backing with intermediate layers between the ceramic layer and metal substrate. The most severe stresses in the seal, as far as failure is concerned, are tensile stresses at the top of the ceramic layer and shear and normal stresses at the layer interfaces. All these stresses reach their maximum values during the deceleration phase of a test engine cycle. A parametric study was carried out to evaluate the influence of various design parameters on these critical stress values. The influences of material properties and geometric parameters of the ceramic, intermediate, and backing layers were investigated. After the parametric study was completed, a seal system was designed which incorporated materials with beneficial elastic and thermal properties in each layer of the seal. An analysis of the proposed seal design shows an appreciable decrease in the magnitude of the maximum critical stresses over those obtained with earlier configurations.
ERIC Educational Resources Information Center
Chiu, Chung-Yi; Lynch, Ruth Torkelson; Chan, Fong; Rose, Lindsey
2012-01-01
The main objective of this study was to evaluate the health action process approach (HAPA) as a motivational model for dietary self-management for people with multiple sclerosis (MS). Quantitative descriptive research design using path analysis was used. Participants were 209 individuals with MS recruited from the National MS Society and a…
ERIC Educational Resources Information Center
Chang, Hsiu-Ju
2016-01-01
This research focus on the temporal path analysis of learning stress, test anxiety, peer stress (classmate relatedness), teacher relatedness, autonomy, and self-regulative performance in junior high school. Owing to the processes of self-determination always combines several negotiations with the interactive perceptions of personal experiences and…
ERIC Educational Resources Information Center
Wooten, William
1993-01-01
When knowledge, skills, and abilities of four job classes (secretarial/clerical, managerial/administrative, professional/technical, service) were identified, 68% of those determined important for managerial/administrative were also important for secretarial/clerical. Job analysis proved useful in identifying possible career paths, and potential…
ERIC Educational Resources Information Center
Kelly, William E.
2010-01-01
The relation between reading for pleasure, night-sky watching interest, and openness to experience were examined in a sample of 129 college students. Results of a path analysis examining a mediation model indicated that the influence of night-sky interest on reading for pleasure was not mediated by the broad personality domain openness to…
ERIC Educational Resources Information Center
Hu, Chun-mei; Cui, Shu-jing; Wang, Lei
2016-01-01
Objective: To investigate the path analysis of work family conflict, job salary and promotion satisfaction, work engagement to subjective well-being of the primary and middle school principals, and provide advice for enhancing their well-being. Methods: Using convenient sampling, totally 300 primary and middle school principals completed the WFC,…
Exploring the association between speed and safety: A path analysis approach.
Gargoum, Suliman A; El-Basyouny, Karim
2016-08-01
Road safety is influenced by many factors; these factors include characteristics of the road, climate, traffic and, most importantly, vehicle speeds. Previous research shows that increases in speed are typically associated with an increased collision risk. Moreover, previous studies have also found relationships between road and traffic characteristics and collisions. In addition, these features have also been found to affect speeds. This paper aims to model all the aforementioned relationships simultaneously using a Structural Equation Modelling approach. More specifically, the paper attempts to model the relationship between average speed and collision frequency, while taking into account the effects of factors that confound the relationship. Moreover, the analysis attempts to assess the mediated effects that some variables have on collisions through their effects on speed. The data used in this study originated from 353 two-lane urban roads in the city of Edmonton, Canada. The average speeds were obtained from 35 million speed survey observations collected over a five-year period. The speed data are linked to the crash frequency at each location during the same time frame, along with the other factors (road, traffic and climate). The results show that, among others, average speed, volume, segment length, medians and horizontal curves all have statistically significant effects on collisions. On the other hand, shoulders, speed limits and vehicle-lengths are some variables that significantly influence speeds. The results also show that the effects of some variables on safety are indeed mediated through speeds (both partial and full mediation is observed). These findings provide valuable insight that may assist decision makers in choosing and developing alternative speed management strategies, which, in turn, could help improve safety. PMID:27163700
Analysis of five forest harvesting simulation models. II. Paths, pitfalls, and other considerations
Goulet, D.V.; Iff, R.H.; Sirois, D.L.
1980-01-01
This is the second of two papers describing the conclusions from a study to determine the state of the art in timber harvesting computer simulation modeling. Five models were evaluated -- Forest Harvesting Simulation Model (FHSM), Full Tree Field Chipping (FTFC), Harvesting System Simulator (HSS), Simulation Applied to Logging Systems (SAPLOS), and Timber Harvesting and Transport Simulator (THATS) -- for their potential use in southern forest harvesting operations. In Part I, modeling characteristics and overall model philosophy were identified and illustrated. This included a detailed discussion of the wood flow process in each model, accounting strategies for productive/nonproductive times, performance variables used, and the different harvesting systems modelable. In Part II user implementation problems are discussed. Those dealt with in detail are the following: What questions can be asked of the model. What are the modeling tradeoffs, and how do they impact on the analysis. What are the computer skills necessary to work effectively with the model. What computer support is needed. Are the models operational. The results provide a good picture of the state of the art in timber harvesting computer simulation. Much learning has occurred in the generation of these models, and many modeling and implementation problems have been uncovered, some of which remain unsolved. Hence, the user needs to examine closely the model and the intended application so that results will represent useable, valid data. It is recommended that the development of timber harvesting computer simulation modeling continue so that existing and proposed timber harvesting strategies can be adequately evaluated. Design criteria are proposed. (Refs. 22).
NASA Astrophysics Data System (ADS)
Wang, Z.; Ireland, P. T.; Jones, T. V.
1995-04-01
The heat transfer coefficient over the surface of a pedestal with fillet radii has been measured using thermochromic liquid crystals and the transient heat transfer method. The tests were performed at engine representative Reynolds numbers for a geometry typical of those used in turbine blade cooling systems. The heat conduction process that occurs in the engine was subsequently modeled numerically with a finite element discretization of the solid pedestal. The measured heat transfer coefficients were used to derive the exact boundary conditions applicable to the engine. The temperature field within the pedestal, calculated using the correct heat transfer coefficient distribution, is compared to that calculated using an area-averaged heat transfer coefficient. Metal temperature differences of 90 K are predicted across the blade wall.
Technology Transfer Automated Retrieval System (TEKTRAN)
Many quantitative and qualitative traits interact to affect lint yield in upland cotton. Breeders should be aware of these traits and their interactions before embarking on a breeding program to improve lint yield. In this study, twelve diverse germplasm lines of upland cotton were used to investiga...
Nagashima, H; Tsuda, S; Tsuboi, N; Koshi, M; Hayashi, K A; Tokumasu, T
2014-04-01
In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density-temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure-volume-temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases. PMID:24712800
Chen, Liang; Yang, Zhifeng; Chen, Bin
2013-01-01
This paper presents a forecast and analysis of population, economic development, energy consumption and CO2 emissions variation in China in the short- and long-term steps before 2020 with 2007 as the base year. The widely applied IPAT model, which is the basis for calculations, projections, and scenarios of greenhouse gases (GHGs) reformulated as the Kaya equation, is extended to analyze and predict the relations between human activities and the environment. Four scenarios of CO2 emissions are used including business as usual (BAU), energy efficiency improvement scenario (EEI), low carbon scenario (LC) and enhanced low carbon scenario (ELC). The results show that carbon intensity will be reduced by 40-45% as scheduled and economic growth rate will be 6% in China under LC scenario by 2020. The LC scenario, as the most appropriate and the most feasible scheme for China's low-carbon development in the future, can maximize the harmonious development of economy, society, energy and environmental systems. Assuming China's development follows the LC scenario, the paper further gives four paths of low-carbon transformation in China: technological innovation, industrial structure optimization, energy structure optimization and policy guidance. PMID:24204922
NASA Astrophysics Data System (ADS)
Cano, Francisco; García, Ángela; Berbén, A. B. G.; Justicia, Fernando
2014-07-01
The purpose of this research was to build and test a conceptual model of the complex interrelationships between students' learning in science (learning approaches and self-regulation), their reading comprehension, question-asking in class and science achievement. These variables were measured by means of a test and a series of questionnaires administered to 604 ninth-grade students, and the data collected were analysed using a correlational, cross-sectional design. Results of a path analysis indicated that (a) students' self-regulated and intentional knowledge-constructing activity (self-regulated strategy use, deep approach and knowledge-building) were what chiefly accounted for their question-asking in class; (b) question-asking (high and low levels) was related directly to reading comprehension and indirectly, through its contribution to the this, to academic achievement; (c) reading comprehension was directly and negatively associated with surface approach and indirectly and positively related to deep approach and knowledge-building; and (d) some of these variables, particularly reading comprehension, accounted for academic achievement in science. This model explained nearly 30% of the variance in academic achievement and provided a substantial and distinctive insight into the web of interrelationships among these variables. Implications for future research and science teaching and learning are discussed (e.g. the importance of supporting students' efforts to learn science in a meaningful, active and self-regulated way and of improving their reading comprehension).
Going to work ill: A meta-analysis of the correlates of presenteeism and a dual-path model.
Miraglia, Mariella; Johns, Gary
2016-07-01
Interest in presenteeism, attending work while ill, has flourished in light of its consequences for individual well-being and organizational productivity. Our goal was to identify its most significant causes and correlates by quantitatively summarizing the extant research. Additionally, we built an empirical model of some key correlates and compared the etiology of presenteeism versus absenteeism. We used meta-analysis (in total, K = 109 samples, N = 175,965) to investigate the correlates of presenteeism and meta-analytic structural equation modeling to test the empirical model. Salient correlates of working while ill included general ill health, constraints on absenteeism (e.g., strict absence policies, job insecurity), elevated job demands and felt stress, lack of job and personal resources (e.g., low support and low optimism), negative relational experiences (e.g., perceived discrimination), and positive attitudes (satisfaction, engagement, and commitment). Moreover, our dual process model clarified how job demands and job and personal resources elicit presenteeism via both health impairment and motivational paths, and they explained more variation in presenteeism than absenteeism. The study sheds light on the controversial act of presenteeism, uncovering both positive and negative underlying mechanisms. The greater variance explained in presenteeism as opposed to absenteeism underlines the opportunities for researchers to meaningfully investigate the behavior and for organizations to manage it. (PsycINFO Database Record PMID:26550958
Nagashima, H.; Tsuda, S.; Tsuboi, N.; Koshi, M.; Hayashi, K. A.; Tokumasu, T.
2014-04-07
In this paper, we describe the analysis of the thermodynamic properties of cryogenic hydrogen using classical molecular dynamics (MD) and path integral MD (PIMD) method to understand the effects of the quantum nature of hydrogen molecules. We performed constant NVE MD simulations across a wide density–temperature region to establish an equation of state (EOS). Moreover, the quantum effect on the difference of molecular mechanism of pressure–volume–temperature relationship was addressed. The EOS was derived based on the classical mechanism idea only using the MD simulation results. Simulation results were compared with each MD method and experimental data. As a result, it was confirmed that although the EOS on the basis of classical MD cannot reproduce the experimental data of saturation property of hydrogen in the high-density region, the EOS on the basis of PIMD well reproduces those thermodynamic properties of hydrogen. Moreover, it was clarified that taking quantum effects into account makes the repulsion force larger and the potential well shallower. Because of this mechanism, the intermolecular interaction of hydrogen molecules diminishes and the virial pressure increases.
Meulemans, Shelli; Pribis, Peter; Grajales, Tevni; Krivak, Gretchen
2014-01-01
The purpose of our study was to study the prevalence of exercise dependence (EXD) among college students and to investigate the role of EXD and gender on exercise behavior and eating disorders. Excessive exercise can become an addiction known as exercise dependence. In our population of 517 college students, 3.3% were at risk for EXD and 8% were at risk for an eating disorder. We used Path analysis the simplest case of Structural Equation Modeling (SEM) to investigate the role of EXD and exercise behavior on eating disorders. We observed a small direct effect from gender to eating disorders. In females we observed significant direct effect between exercise behavior (r = −0.17, p = 0.009) and EXD (r = 0.34, p < 0.001) on eating pathology. We also observed an indirect effect of exercise behavior on eating pathology (r = 0.16) through EXD (r = 0.48, r2 = 0.23, p < 0.001). In females the total variance of eating pathology explained by the SEM model was 9%. In males we observed a direct effect between EXD (r = 0.23, p < 0.001) on eating pathology. We also observed indirect effect of exercise behavior on eating pathology (r = 0.11) through EXD (r = 0.49, r2 = 0.24, p < 0.001). In males the total variance of eating pathology explained by the SEM model was 5%. PMID:25379689
Chen, Liang; Yang, Zhifeng; Chen, Bin
2013-01-01
This paper presents a forecast and analysis of population, economic development, energy consumption and CO2 emissions variation in China in the short- and long-term steps before 2020 with 2007 as the base year. The widely applied IPAT model, which is the basis for calculations, projections, and scenarios of greenhouse gases (GHGs) reformulated as the Kaya equation, is extended to analyze and predict the relations between human activities and the environment. Four scenarios of CO2 emissions are used including business as usual (BAU), energy efficiency improvement scenario (EEI), low carbon scenario (LC) and enhanced low carbon scenario (ELC). The results show that carbon intensity will be reduced by 40–45% as scheduled and economic growth rate will be 6% in China under LC scenario by 2020. The LC scenario, as the most appropriate and the most feasible scheme for China’s low-carbon development in the future, can maximize the harmonious development of economy, society, energy and environmental systems. Assuming China's development follows the LC scenario, the paper further gives four paths of low-carbon transformation in China: technological innovation, industrial structure optimization, energy structure optimization and policy guidance. PMID:24204922
Meulemans, Shelli; Pribis, Peter; Grajales, Tevni; Krivak, Gretchen
2014-11-01
The purpose of our study was to study the prevalence of exercise dependence (EXD) among college students and to investigate the role of EXD and gender on exercise behavior and eating disorders. Excessive exercise can become an addiction known as exercise dependence. In our population of 517 college students, 3.3% were at risk for EXD and 8% were at risk for an eating disorder. We used Path analysis the simplest case of Structural Equation Modeling (SEM) to investigate the role of EXD and exercise behavior on eating disorders. We observed a small direct effect from gender to eating disorders. In females we observed significant direct effect between exercise behavior (r = -0.17, p = 0.009) and EXD (r = 0.34, p < 0.001) on eating pathology. We also observed an indirect effect of exercise behavior on eating pathology (r = 0.16) through EXD (r = 0.48, r2 = 0.23, p < 0.001). In females the total variance of eating pathology explained by the SEM model was 9%. In males we observed a direct effect between EXD (r = 0.23, p < 0.001) on eating pathology. We also observed indirect effect of exercise behavior on eating pathology (r = 0.11) through EXD (r = 0.49, r2 = 0.24, p < 0.001). In males the total variance of eating pathology explained by the SEM model was 5%. PMID:25379689
NASA Astrophysics Data System (ADS)
Man, O.
The particular componets of NRM, formed by various processes during the geological history, can be distinguished by the progressive demagnetization technique provided that they differ from one another in the blocking temperature distributions. A sequence of three-dimensional vectors (assigned to fixed values of blocking temperature) result- ing from this experiment is called the demagnetization path. The present method of its analysis, consisting in finding its linear segments, is tested in the present paper to- gether with the techniques suggested herein. The following mathematical model of the demagnetization path is used for this purpose: Each component of NRM is supposed to be described by a vector of magnetization and a function of distribution of blocking temperature; two types of distribution are considered, namely the gamma distribution and the normal one. Both types are defined by two parameters and, therefore, each component of NRM is described by five parameters. Moreover, the model of demag- netization path is completed by superimposing Gaussean white noise (representing, e.g., the measurement errors) on the above model of NRM. The tests prove that the present method of identification of NRM components fails if either the distributions of blocking temperature overlap one another or the noise level is too high. The suggested method of analysis of the demagnetization path consists in maximum likelihood esti- mation of all parameters describing the NRM model, i.e., in an iterative minimization of deflections of this model from the demagnetization path. The minimization yields a correct estimate of parameters on condition that their initial guess is sufficiently close to their actual values. The initial guess may be found by formal smoothing of the demagnetization path by a spline function.
NASA Astrophysics Data System (ADS)
Kröger, Martin
2005-06-01
We present an algorithm which returns a shortest path and related number of entanglements for a given configuration of a polymeric system in 2 or 3 dimensions. Rubinstein and Helfand, and later Everaers et al. introduced a concept to extract primitive paths for dense polymeric melts made of linear chains (a multiple disconnected multibead 'path'), where each primitive path is defined as a path connecting the (space-fixed) ends of a polymer under the constraint of non-interpenetration (excluded volume) between primitive paths of different chains, such that the multiple disconnected path fulfills a minimization criterion. The present algorithm uses geometrical operations and provides a—model independent—efficient approximate solution to this challenging problem. Primitive paths are treated as 'infinitely' thin (we further allow for finite thickness to model excluded volume), and tensionless lines rather than multibead chains, excluded volume is taken into account without a force law. The present implementation allows to construct a shortest multiple disconnected path (SP) for 2D systems (polymeric chain within spherical obstacles) and an optimal SP for 3D systems (collection of polymeric chains). The number of entanglements is then simply obtained from the SP as either the number of interior kinks, or from the average length of a line segment. Further, information about structure and potentially also the dynamics of entanglements is immediately available from the SP. We apply the method to study the 'concentration' dependence of the degree of entanglement in phantom chain systems. Program summaryTitle of program:Z Catalogue number:ADVG Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADVG Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: Silicon Graphics (Irix), Sun (Solaris), PC (Linux) Operating systems or monitors under which the
NASA Astrophysics Data System (ADS)
Reyes, J. M.; Martinez, M. D.; Lana, X.
2003-04-01
This work aims to apply a previously tested methodology to assess the path coverage of a domain from a tomographic viewpoint, and for the design of an improved or new seismic network. Some concepts of mathematical information theory have been used with the aim of evaluating the current epicentre-station path coverage offered by a set of seismic stations in NE Spain and SE France for a body-wave tomography study. The path coverage is analysed for different epicentral distance ranges. This process constitutes the first step for the determination in the next future of the crust and upper mantle structure in this geographic area from the inversion of P and S first-arrival times. The combination of information theory and Monte Carlo methods permits to design either an enlarged or a new network with the aim of improving the current path coverage
A simple and accurate algorithm for path integral molecular dynamics with the Langevin thermostat.
Liu, Jian; Li, Dezhang; Liu, Xinzijian
2016-07-14
We introduce a novel simple algorithm for thermostatting path integral molecular dynamics (PIMD) with the Langevin equation. The staging transformation of path integral beads is employed for demonstration. The optimum friction coefficients for the staging modes in the free particle limit are used for all systems. In comparison to the path integral Langevin equation thermostat, the new algorithm exploits a different order of splitting for the phase space propagator associated to the Langevin equation. While the error analysis is made for both algorithms, they are also employed in the PIMD simulations of three realistic systems (the H2O molecule, liquid para-hydrogen, and liquid water) for comparison. It is shown that the new thermostat increases the time interval of PIMD by a factor of 4-6 or more for achieving the same accuracy. In addition, the supplementary material shows the error analysis made for the algorithms when the normal-mode transformation of path integral beads is used. PMID:27421393
A simple and accurate algorithm for path integral molecular dynamics with the Langevin thermostat
NASA Astrophysics Data System (ADS)
Liu, Jian; Li, Dezhang; Liu, Xinzijian
2016-07-01
We introduce a novel simple algorithm for thermostatting path integral molecular dynamics (PIMD) with the Langevin equation. The staging transformation of path integral beads is employed for demonstration. The optimum friction coefficients for the staging modes in the free particle limit are used for all systems. In comparison to the path integral Langevin equation thermostat, the new algorithm exploits a different order of splitting for the phase space propagator associated to the Langevin equation. While the error analysis is made for both algorithms, they are also employed in the PIMD simulations of three realistic systems (the H2O molecule, liquid para-hydrogen, and liquid water) for comparison. It is shown that the new thermostat increases the time interval of PIMD by a factor of 4-6 or more for achieving the same accuracy. In addition, the supplementary material shows the error analysis made for the algorithms when the normal-mode transformation of path integral beads is used.
Fontaine, Daniel; Narine, Nadira
2012-01-01
Objective To compare unsatisfactory rates between the two major liquid-based cytology (LBC) platforms, namely ThinPrep (Hologic) and SurePath (Becton Dickinson). Design The authors performed both a systematic review and a meta-analysis. Inclusion criteria were English language, data presented on unsatisfactory rates for either ThinPrep or SurePath, utilising actual patient samples (ie, not laboratory manipulated samples) and no manipulation using acetic acid to increase the satisfactory rate. The authors searched PubMed for articles using the keywords ‘SurePath’ or ‘ThinPrep’ and ‘unsatisfactory’. References of retrieved studies were searched for additional articles. Key researchers in the field were also contacted. Participants and interventions Eligible studies were reviewed for rates of unsatisfactory cervical cytology smears processed on either the ThinPrep or SurePath platforms (compared with a general linear model) or data on unsatisfactory rates for both platforms for the same laboratory and the same patient population (compared with a meta-analysis using a random effects model and pooled RR). Primary Outcome Measure Unsatisfactory rate of cervical cytology smears. Results A total of 1 120 418 cervical cytology smears were reported in 14 different studies using the SurePath platform for an overall unsatisfactory rate (weighted average) of 0.3%. 28 studies reported on 1 148 755 smears prepared using the ThinPrep platform for an overall unsatisfactory rate (weighted average) of 1.3%. The general linear model did not show a difference between LBC platforms when other variables were controlled for; however, the power to detect a difference (0.087) was very low. The meta-analysis performed on four studies where both ThinPrep and SurePath results were reported from the same laboratory showed fewer unsatisfactory tests from the SurePath platform (RR 0.44, 95% CI 0.25 to 0.77, p=0.004). Conclusions Multiple factors affect LBC unsatisfactory rates
Hanover, R.H.
1994-01-01
A cross-sectional analysis of ground-water flow in central-western and northwestern Ohio was done as part of the Midwestern Basins and Arches Regional Aquifer-System Analysis project. The Midwestern Basins and Arches aquifer system is composed of carbonate bedrock of Silurian and Devonian age and overlying glacial flow analysis of the Scioto and Blanchard rivers in the study area were used to describe patrems of ground-water flow, to evaluate stream-aquifer interaction, and to quantify recharge and discharge within the ground-water-flow system along a regional ground-water-flow path. The selected regional flow path begins at a regional topographic high in Logan County, Ohio, and ends in Sandusky Bay (Lake Erie), a regional topographic low. Recharge to the ground-water system along the selected regional flow path was estimated from hydrograph separation of streamflow and averaged 3.24 inches per year. Computer model simulations indicate that 84 percent of the water entering the ground-water system flows less than 5 miles from point of recharge to point of discharge and no deeper than the upper surficial aquifers. The distance and depth that ground water travels and traveltime from point of recharge to point of discharge is controlled largely by where ground water enters the flow system. Ground water entering the flow system in the vicinity of major surface- water divides generally travels further, deeper, and longer than ground water entering the flow system elsewhere along the regional flow path. Particle tracking simulations substantiate the concept that the 80-mile-long regional flow path is within a continuous ground-water basin. Estimated traveltimes for ground-water from the regional high to Sandusky Bay range from 22,000 to 40,700 years, given a range of porosities from 8 to 22 percent for the carbonate-rock aquifer.
Velpuri, N.M.; Senay, G.B.
2013-01-01
This study investigates the long-term trends in precipitation, runoff and runoff coefficient in major urban watersheds in the United States. The seasonal Mann–Kendall trend test was performed on monthly precipitation, runoff and runoff coefficient data from 1950 to 2009 obtained from 62 urban watersheds covering 21 major urban centers in the United States. The results indicate that only five out of 21 urban centers in the United States showed an uptrend in precipitation. Twelve urban centers showed an uptrend in runoff coefficient. However, six urban centers did not show any trend in runoff coefficient, and three urban centers showed a significant downtrend. The highest rate of change in precipitation, runoff and runoff coefficient was observed in the Houston urban watershed. Based on the results obtained, we also attributed plausible causes for the trends. Our analysis indicated that while a human only influence is observed in most of the urban watersheds, a combined climate and human influence is observed in the central United States.
Yuan, Chuang; Wang, Jing; Ying, Michael
2016-01-01
Aims The aim of the present study is to determine the pooled predictive value of carotid distensibility coefficient (DC) for cardiovascular (CV) diseases and all-cause mortality. Background Arterial stiffness is associated with future CV events. Aortic pulse wave velocity is a commonly used predictor for CV diseases and all-cause mortality; however, its assessment requires specific devices and is not always applicable in all patients. In addition to the aortic artery, the carotid artery is also susceptible to atherosclerosis, and is highly accessible because of the surficial property. Thus, carotid DC, which indicates the intrinsic local stiffness of the carotid artery and may be determined using ultrasound and magnetic resonance imaging, is of interest for the prediction. However, the role of carotid DC in the prediction of CV diseases and all-cause mortality has not been thoroughly characterized, and the pooled predictive value of carotid DC remains unclear. Methods A meta-analysis, which included 11 longitudinal studies with 20361 subjects, was performed. Results Carotid DC significantly predicted future total CV events, CV mortality and all-cause mortality. The pooled risk ratios (RRs) of CV events, CV mortality and all-cause mortality were 1.19 (1.06–1.35, 95%CI, 9 studies with 18993 subjects), 1.09 (1.01–1.18, 95%CI, 2 studies with 2550 subjects) and 1.65 (1.15–2.37, 95%CI, 6 studies with 3619 subjects), respectively, for the subjects who had the lowest quartile of DC compared with their counterparts who had higher quartiles. For CV events, CV mortality and all-cause mortality, a decrease in DC of 1 SD increased the risk by 13%, 6% and 41% respectively, whereas a decrease in DC of 1 unit increased the risk by 3%, 1% and 6% respectively. Conclusions Carotid DC is a significant predictor of future CV diseases and all-cause mortality, which may facilitate the identification of high-risk patients for the early diagnosis and prompt treatment of CV diseases
Standardized Discriminant Coefficients: A Rejoinder.
ERIC Educational Resources Information Center
Mueller, Ralph O.; Cozad, James B.
1993-01-01
Although comments of D.J. Nordlund and R. Nagel are welcomed, their arguments are not sufficient to accept the recommendation of using total variance estimates to standardize canonical discriminant function coefficients. If standardized coefficients are used to help interpret a discriminant analysis, pooled within-group variance estimates should…
NASA Astrophysics Data System (ADS)
Piasecka, Magdalena; Maciejewska, Beata
2015-05-01
The paper presents flow boiling heat transfer of FC-72 in 1 mm depth, 40 mm width minichannel where a foil with evenly distributed recesses on one side acts as a heating surface. The minichannel is set at various angles, i.e. 0, 45, 90, 135 and 180 degrees inclinations in relation to the horizontal plane. The plain side of the foil is observed to determine the surface temperature by liquid crystal thermography. Two heat transfer models: one- and two-dimensional are proposed to calculate local heat transfer coefficients. In the two-dimensional approach the inverse problem in the heating wall is solved by the semi-analytical method based on Trefftz functions in subareas, abbreviated to the nodeless Trefftz method. Local values of heat transfer coefficient on the surface between the heating foil and boiling liquid were calculated on the basis of the third-kind boundary condition. The influence of minichannel orientation on heat transfer coefficient at boiling incipience region values were analyzed. The same tendencies in the results were observed for the two applied methods. The one-dimensional approach seems to be less sensitive to measurement errors. The polynomial smoothing of the results applied in the two-dimensional method can affect the rounding values of coefficient.
AllamehZadeh, Mostafa
2011-12-15
A Quadratic Neural Networks (QNNs) model has been developed for identifying seismic source classification problem at regional distances using ARMA coefficients determination by Artificial Neural Networks (ANNs). We have devised a supervised neural system to discriminate between earthquakes and chemical explosions with filter coefficients obtained by windowed P-wave phase spectra (15 s). First, we preprocess the recording's signals to cancel out instrumental and attenuation site effects and obtain a compact representation of seismic records. Second, we use a QNNs system to obtain ARMA coefficients for feature extraction in the discrimination problem. The derived coefficients are then applied to the neural system to train and classification. In this study, we explore the possibility of using single station three-component (3C) covariance matrix traces from a priori-known explosion sites (learning) for automatically recognizing subsequent explosions from the same site. The results have shown that this feature extraction gives the best classifier for seismic signals and performs significantly better than other classification methods. The events have been tested, which include 36 chemical explosions at the Semipalatinsk test site in Kazakhstan and 61 earthquakes (mb = 5.0-6.5) recorded by the Iranian National Seismic Network (INSN). The 100% correct decisions were obtained between site explosions and some of non-site events. The above approach to event discrimination is very flexible as we can combine several 3C stations.
NASA Astrophysics Data System (ADS)
Cekmen, Z. C.; Dincer, M. S.
2009-07-01
The effective ionization coefficients and transport parameters such as electron mean energy drift velocity and transverse diffusion coefficient in binary and ultradilute SF6-Ar gas mixtures have been calculated for density reduced electric field strength E/N values from 10 to 400 Td. These calculations have been performed by using the two-term spherical harmonic expansion to obtain the numerical solution of the Boltzmann transport equation based on the finite element method under steady-state Townsend condition. In order to confirm the model and code developed in this study, the Reid ramp model has been used as a benchmark test and then effective ionization coefficients and transport parameters have been evaluated for SF6 contents of 1%, 10%, 25%, 50%, 70% and 100% in the binary mixture. Finally SF6 contents in the ultradilute mixtures of 0.1%, 0.3%, 0.5% and 0.7% are taken into account with the evaluated effective ionizations and transport parameters of electron mean energy, drift velocity and transverse diffusion coefficients.
Potential risk and its influencing factors for separated bicycle paths.
Xu, Cheng; Yang, Ying; Jin, Sheng; Qu, Zhaowei; Hou, Lei
2016-02-01
In this paper, we propose two potential risk indicators to define and evaluate the safety of bicycle path at the microscopic level. Field bicycle data were collected from three survey sites under different traffic conditions. These two risk indicators based on speed dispersion were proposed and calculated during each 5-min interval. The risk influences of various widths of bicycle path and traffic conditions were analyzed by using one-way ANOVA. We further proposed a generalized linear model (GLM) for modeling and analyzing the relationships between bicycle risks and v/c ratio and percentages of electric bicycles, male cyclists, young cyclists, and loaded cyclists. The stepwise regression models were applied for determination of coefficients. The results show that the influences of gender and age of cyclists on potential risks are not significant. The risks increase with the width of bicycle path and percentage of electric bicycles, while only for wider bicycle path (4-lane case in this study), the risks are associated with whether or not cyclists are loaded. The findings could contribute for analysis and evaluation of the safety for bicycle path. PMID:26647016
Davidson, J.W.; Dudziak, D.J.; Higgs, C.E.; Stepanek, J.
1988-01-01
AARE, a code package to perform Advanced Analysis for Reactor Engineering, is a linked modular system for fission reactor core and shielding, as well as fusion blanket, analysis. Its cross-section sensitivity and uncertainty path presently includes the cross-section processing and reformatting code TRAMIX, cross-section homogenization and library reformatting code MIXIT, the 1-dimensional transport code ONEDANT, the 2-dimensional transport code TRISM, and the 1- and 2- dimensional cross-section sensitivity and uncertainty code SENSIBL. IN the present work, a short description of the whole AARE system is given, followed by a detailed description of the cross-section sensitivity and uncertainty path. 23 refs., 2 figs.
NASA Astrophysics Data System (ADS)
Nganhou, J.; Njomo, D.; Bénet, J. C.; Augier, F.; Berthomieu, G.
2003-09-01
This article is about the study of the diffusion of water and acetic acid in a grain of cocoa in course of drying. The authors present a method of microanalysis which enables the analysis of each little slice of the grain : a precise measurement of each slice is realised in view of the analysis from the centre to the surface of the grain with the aid of a cutting apparatus, designed and realised to this effect. At each instant of the drying process, the profiles of water and acetic acid contents are then determined. A one dimensional diffusion model enables a shell by shell evaluation of the diffusion of water and acid in the cocoa grain. The results obtained show an augmentation of transport coefficients in course of drying. We however observe a decrease of the diffusion coefficient of water to the low moisture content : what makes us think of the appearance of crusting phenomenon.
ERIC Educational Resources Information Center
Sheu, Hung-Bin; Lent, Robert W.; Brown, Steven D.; Miller, Matthew J.; Hennessy, Kelly D.; Duffy, Ryan D.
2010-01-01
Social cognitive career theory (SCCT; Lent, Brown, & Hackett, 1994) seeks to explain the factors that shape educational and vocational interests and choices. We used meta-analytic path analyses to synthesize data (from 1981 to 2008) relevant to SCCT's interest and choice hypotheses, organizing the literature according to Holland's (1997) broad…
NASA Astrophysics Data System (ADS)
Kajikawa, Y.
2016-02-01
The experimental data on the temperature dependence of the four transport coefficients, i.e., the electrical conductivity (σ), Hall coefficient (RH), Seebeck coefficient (S), and Nernst coefficient (Q), of n-type Co0.999Ni0.001Sb3 reported by Sun et al. [Nat. Commun. 6, 7475 (2015)] have been analyzed in a multi-band model, especially focusing on the low temperature data. The multi-band model includes not only the lowest valley of the conduction band at the Γ point but also satellite valleys at the second minima together with an impurity band. The lowest valley at the Γ point is assumed to split into the c1 band and the spin-orbit split-off (so) band. For the analysis, the general expression of the Nernst coefficient in the multi-band model is derived. At such low temperatures that the other bands than the c1 and the impurity band can be neglected, this expression is shown to be approximated as the sum of three terms: the intrinsic terms due to the Nernst coefficients in the two bands themselves and a cross term proportional to the difference of Seebeck coefficients between the two bands. As a result of the analysis, it is proved that the anomalous positive peak of S(T) observed around T = 20 K as well as the sharp rise of the Hall mobility observed from 15 K to 40 K are due to the transition from hopping conduction in the impurity band to conduction in the c1 band. On the other hand, the pronounced peak of Q(T) observed slightly below 40 K is proved to be due to the cross term between the impurity band and the c1 band. In addition, a shoulder of Q(T) appeared around T = 80 K lends clear evidence of the existence of the so band, while the increase in both of σ(T) and | S ( T ) | above 150 K suggests the existence of the satellite valleys.
NASA Astrophysics Data System (ADS)
Stecca, Guglielmo; Siviglia, Annunziato; Blom, Astrid
2014-05-01
synchronous approach, by which all the variables are updated simultaneously. The non-conservative problem which stems from the developed matrix-vector formulation is solved using path-conservative methods. We perform numerical applications by comparison with the above linearised solutions and with the data from laboratory experiments. Results show that our solution approach is robust, general and accurate. References - Hirano, M. (1971), River bed degradation with armoring, Trans. Jpn. Soc. Civ. Eng., (3), 194-195. - Hirano, M. (1972), Studies on variation and equilibrium state of a river bed composed of nonuniform material, Trans. Jpn. Soc. Civ. Eng., (4), 128-129. - Stecca, G., A. Siviglia, and A. Blom, Mathematical analysis of the Saint-Venant-Hirano model for mixed-sediment morphodynamics, Submitted to Water Resources Research
NASA Technical Reports Server (NTRS)
Beatty, R. W.; Otosh, T. Y.
1978-01-01
Theoretical equations are derived for calculating the effects of local VSWR and reflection coefficient phase angle drifts on hydrogen maser frequency stability. Sample calculations made for a typical JPL maser show that under special load conditions, a VSWR drift of 0.000075/h or phase angle drive of 0.01 deg/h can produce a frequency drift of (10 to the -14th power f sub 0) Hz/h where f sub 0 is the maser frequency of approximately 1.42 x 10 to the 9th power Hz.
Standards for Standardized Logistic Regression Coefficients
ERIC Educational Resources Information Center
Menard, Scott
2011-01-01
Standardized coefficients in logistic regression analysis have the same utility as standardized coefficients in linear regression analysis. Although there has been no consensus on the best way to construct standardized logistic regression coefficients, there is now sufficient evidence to suggest a single best approach to the construction of a…
Sadana, A
1998-01-01
The diffusion-limited binding kinetics of antigen (analyte), in solution with antibody (receptor) immobilized on a biosensor surface, is analyzed within a fractal framework. Most of the data presented is adequately described by a single-fractal analysis. This was indicated by the regression analysis provided by Sigmaplot. A single example of a dual-fractal analysis is also presented. It is of interest to note that the binding-rate coefficient (k) and the fractal dimension (Df) both exhibit changes in the same and in the reverse direction for the antigen-antibody systems analyzed. Binding-rate coefficient expressions, as a function of the Df developed for the antigen-antibody binding systems, indicate the high sensitivity of the k on the Df when both a single- and a dual-fractal analysis are used. For example, for a single-fractal analysis, and for the binding of antibody Mab 0.5 beta in solution to gp120 peptide immobilized on a BIAcore biosensor, the order of dependence on the Df was 4.0926. For a dual-fractal analysis, and for the binding of 25-100 ng/mL TRITC-LPS (lipopolysaccharide) in solution with polymyxin B immobilized on a fiberoptic biosensor, the order of dependence of the binding-rate coefficients, k1 and k2, on the fractal dimensions, Df1 and Df2, were 7.6335 and -11.55, respectively. The fractional order of dependence of the k(s) on the Df(s) further reinforces the fractal nature of the system. The k(s) expressions developed as a function of the Df(s) are of particular value, since they provide a means to better control biosensor performance, by linking it to the heterogeneity on the surface, and further emphasize, in a quantitative sense, the importance of the nature of the surface in biosensor performance. PMID:9779572
NASA Astrophysics Data System (ADS)
Battista Chirico, Giovanni; Forzieri, Giovanni; Preti, Federico
2014-05-01
Flood frequency is fundamental for planning and design structural and non-structural mitigation strategies against land degradation. Flood frequency analysis aims at estimating the probability distributions of flood peaks, so that the flood magnitude for any design return period can be easily determined. The approach commonly employed in engineering hydrology in ungauged catchments is the regional analysis, which exploits the hydrological similarities among catchments and the scaling properties of flood statistics for exporting the information available in gauged catchments to ungauged catchments. One of method most widely applied by hydrologists and engineers is the index flood method, based on the identification of homogeneous regions, where the probability distributions of the annual maximum floods are assumed invariant except for a site-specific scale parameter known as the index flood. The index flood is generally assumed coincident with the mean of annual maximum of flood peaks and is estimated by indirect methods. An indirect estimation method largely applied is based on a conceptual model structured according to the well-known rational formula. A key parameter of the rational formula is the runoff coefficient, which can be interpreted as a probabilistic factor controlling not only the position but also the slope and the curvature of the flood frequency curve. Provided that vegetation patterns can have a significant influence on the catchment antecedent conditions as well as on other rainfall runoff processes in rural catchments, in this study we explore to what extent forest cover can be employed to predict the runoff coefficient, in the framework of a regional flood frequency analysis based on the rational formula coupled with a regional analysis of annual maximum rainfall depths. The results of a k-means cluster analysis applied to a data set of 75 catchments distributed from South to Central Italy, evidenced that the second component of the runoff
Devi, V. Malathy; Rinsland, Curtis P.; Benner, D. C.; Sams, Robert L.; Blake, Thomas A.
2010-06-01
Line positions, intensities, Lorentz self- and N2-broadened half-width coefficients have been measured for PQ3, PQ2, PQ1, RQ0,RQ1, RQ2, and RQ3 sub-band transitions in the 9 fundamental band of 12C2H6. A multispectrum nonlinear least-squares fitting technique was used to fit up to 17 high-resolution (~0.00156 cm-1), room temperature absorption spectra of pure (99.99% chemical purity) natural sample of ethane and lean mixtures of the high-purity ethane diluted with N2. A Bruker IFS 120HR Fourier transform spectrometer located at the Pacific Northwest National Laboratory (PNNL), in Richland, Washington was used to record the data. A standard Voigt line shape was assumed to fit all the data since no line mixing or other non Voigt line shapes were required to fit any of the spectra used in the analysis. Short spectral intervals (~2 to 2.5 cm-1) of all 17 spectra covering a specific PQ or RQ sub band were fit simultaneously. For the first time in an ethane band, pressure-broadened half-width coefficients were determined for each of the torsional-split components. Constraints were used such that the half-width coefficients of both torsional-split components were identical for a specific broadening gas. No pressure-induced shift coefficients were necessary to fit the spectra to their noise level. The present study revealed for the first time the dependence of self- and N2-broadened half-width coefficients upon the J, K quantum numbers of the transitions in ethane. A number of transitions belonging to the 9+ 4- 4 and the 9+2 4-2 4 hot bands were also observed in the fitted regions and measurements were made when possible.
Ludlow, Michelle K; Soudackov, Alexander V; Hammes-Schiffer, Sharon
2010-02-01
Electrochemical proton-coupled electron transfer of an osmium aquo complex attached to a self-assembled monolayer on a gold electrode is studied with a recently developed theoretical formulation. The calculated hydrogen/deuterium kinetic isotope effect for the standard rate constant, the cathodic transfer coefficient at zero overpotential, and the Tafel plot are in excellent agreement with experimental data. The input quantities to the heterogeneous rate constant expressions were calculated with density functional theory in conjunction with dielectric continuum models, and no parameters were fit to experimental data. The theoretical calculations indicate that the asymmetry of the Tafel plot and the deviation of the transfer coefficient at zero overpotential from the standard value of one-half arise from the change in the equilibrium proton donor-acceptor distance upon electron transfer. The direction of the asymmetry and deviation from one-half is determined by the sign of this distance change, and the magnitude of these effects is determined by the magnitude of this distance change, as well as the reorganization energy and the distance dependence of the overlap between the initial and final proton vibrational wave functions. This theory provides experimentally testable predictions for the impact of specific system properties on the qualitative behavior of the Tafel plots. PMID:20067257
Li, Weibin; Kagan, Gerald; Yang, Huan; Cai, Chen; Hopson, Russell; Sweigart, Dwight A; Williard, Paul G
2010-06-18
Development and application of physically separated references for aqueous (1)H DOSY diffusion coefficient-formula weight (D-FW) correlation analysis is reported. Commercially available biological buffers (Tris and HEPES) and a water-soluble alcohol (tert-butanol) were used as physically separated references for a Ru and a Mn complex in D(2)O. This extension of DOSY D-FW analysis expands its applicability to a wide variety of water-soluble molecules or metal complexes, with particular application to green chemistry. PMID:20481557
NASA Astrophysics Data System (ADS)
Che-Aron, Z.; Abdalla, A. H.; Abdullah, K.; Hassan, W. H.
2013-12-01
In recent years, Cognitive Radio (CR) technology has largely attracted significant studies and research. Cognitive Radio Ad Hoc Network (CRAHN) is an emerging self-organized, multi-hop, wireless network which allows unlicensed users to opportunistically access available licensed spectrum bands for data communication under an intelligent and cautious manner. However, in CRAHNs, a lot of failures can easily occur during data transmission caused by PU (Primary User) activity, topology change, node fault, or link degradation. In this paper, an attempt has been made to evaluate the performance of the Multi-Radio Link-Quality Source Routing (MR-LQSR) protocol in CRAHNs under different path failure rate. In the MR-LQSR protocol, the Weighted Cumulative Expected Transmission Time (WCETT) is used as the routing metric. The simulations are carried out using the NS-2 simulator. The protocol performance is evaluated with respect to performance metrics like average throughput, packet loss, average end-to-end delay and average jitter. From the simulation results, it is observed that the number of path failures depends on the PUs number and mobility rate of SUs (Secondary Users). Moreover, the protocol performance is greatly affected when the path failure rate is high, leading to major service outages.
NASA Astrophysics Data System (ADS)
Diot, Emilie; Gavoille, Cyril
In this paper we investigate the structural properties of k-path separable graphs, that are the graphs that can be separated by a set of k shortest paths. We identify several graph families having such path separability, and we show that this property is closed under minor taking. In particular we establish a list of forbidden minors for 1-path separable graphs.
Devi, V. Malathy; Benner, D. Chris; Brown, Linda R.; Smith, Mary A.; Rinsland, C.P.; Sams, Robert L.; Sharpe, Steven W.
2003-01-15
A multispectrum nonlinear least-squares fitting technique has been applied to determine accurate zero-pressure line center positions, Lorentz self-broadening and N2-broadening coefficients and self-induced and N2-induced pressure shift coefficients of transitions in the v6 (E) perpendicular band of 12 CH3D between 1035 and 1270 cm-1. High-resolution room temperature absorption spectra recorded with two Fourier transform spectrometers (FTS) were analyzed together. Three spectra at 0.002 cm-1 resolution recorded using the Bruker IFS 120 HR at Pacific Northwest National Laboratory (PNNL), and fourteen spectra obtained with the McMath-Pierce FTS (0.006 cm-1 resolution) at the National Solar Observatory (NSO) on Kitt Peak were used in the analysis.
Factor Scores, Structure Coefficients, and Communality Coefficients
ERIC Educational Resources Information Center
Goodwyn, Fara
2012-01-01
This paper presents heuristic explanations of factor scores, structure coefficients, and communality coefficients. Common misconceptions regarding these topics are clarified. In addition, (a) the regression (b) Bartlett, (c) Anderson-Rubin, and (d) Thompson methods for calculating factor scores are reviewed. Syntax necessary to execute all four…
Bendib, A.; Tahraoui, A.; Bendib, K.; Mohammed El Hadj, K.; Hueller, S.
2005-03-01
The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path {lambda}{sub ei} compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in the analysis, which allows us to consider with sufficient accuracy to describe plasmas with arbitrary atomic number Z. Practical numerical fits of the transport coefficients are proposed as functions of Z and the collisionality parameter {lambda}{sub ei}/L.
Guevara-García, Alfredo Ireta, Joel; Galván, Marcelo
2015-01-07
Density functional theory based ab initio molecular dynamics is used to obtain microscopic details of the interactions in sodium chloride solutions. By following the changes in the atomic C{sub 6} coefficients under the Tkatchenko-Scheffler’s scheme, we were able to identify two different coordination situations for the Cl{sup −} ion with significant different capabilities to perform dispersion interactions. This capability is enhanced when the ion-ion distance corresponds to the contact ion-pair situation. Also, the oxygen and hydrogen atoms of the water molecules change their aptitudes to interact through van der Waals like terms when they are close to the cation region of the ion-pair. These results have interesting implications on the design of force fields to model electrolyte solutions.
Guevara-García, Alfredo; Ireta, Joel; Galván, Marcelo
2015-01-01
Density functional theory based ab initio molecular dynamics is used to obtain microscopic details of the interactions in sodium chloride solutions. By following the changes in the atomic C6 coefficients under the Tkatchenko-Scheffler's scheme, we were able to identify two different coordination situations for the Cl(-) ion with significant different capabilities to perform dispersion interactions. This capability is enhanced when the ion-ion distance corresponds to the contact ion-pair situation. Also, the oxygen and hydrogen atoms of the water molecules change their aptitudes to interact through van der Waals like terms when they are close to the cation region of the ion-pair. These results have interesting implications on the design of force fields to model electrolyte solutions. PMID:25573569
Optical Path, Phase, and Interference
NASA Astrophysics Data System (ADS)
Newburgh, Ronald
2005-11-01
A powerful tool in wave optics is the concept of optical path length, a notion usually introduced with Fermat's principle.1-3 The analysis of Fermat's principle requires the application of the calculus of variations and the concept of an extremum, ideas too advanced for beginning students. However, the concept has proven its usefulness in the analysis4 of interference experiments such as those of Michelson and Fabry-Perot. In this paper we shall show how optical path length can aid in the analysis of a modified two-slit Young experiment.
Szabo, Z.; Rice, D.E.; Plummer, L.N.; Busenberg, E.; Drenkard, S.; Schlosser, P.
1996-01-01
Groundwater age dating through the combination of transient tracer methods (chlorofluorocarbons (CFCs) and tritium/helium 3 (3H/3He)) and groundwater flow path analysis is useful for investigating groundwater travel times, flow patterns, and recharge rates, as demonstrated by this study of the homogeneous shallow, unconfined Kirkwood-Cohansey aquifer system in the southern New Jersey coastal plain. Water samples for age dating were collected from three sets of nested observation wells (10 wells) with 1.5-m-long screens located near groundwater divides. Three steady state finite difference groundwater flow models were calibrated by adjusting horizontal and vertical hydraulic conductivities to match measured heads and head differences (range, 0.002-0.23 m) among the nested wells, with a uniform recharge rate of 0.46 m per year and porosities of 0.35 (sand) and 0.45 (silt) that were assumed constant for all model simulations and travel time calculations. The simulated groundwater travel times increase with depth in the aquifer, ranging from about 1.5 to 6.5 years for the shallow wells (screen bottoms 3-4 m below the water table), from about 10 to 25 years for the medium-depth wells (screen bottoms 8-19 m below the water table), and from about 30 to more than 40 years for the deep wells (screen bottoms 24-26 m below the water table). Apparent groundwater ages based on CFC- and 3H/3He-dating techniques and model-based travel times could not be statistically differentiated, and all were strongly correlated with depth. Confinement of 3He was high because of the rapid vertical flow velocity (of the order of 1 m/yr), resulting in clear delineation of groundwater travel times based on the 3H/3He-dating technique. The correspondence between the 3H/3He and CFC ages indicates that dispersion has had a minimal effect on the tracer-based ages of water in this aquifer. Differences between the tracer-based apparent ages for seven of the 10 samples were smaller than the error values
NASA Astrophysics Data System (ADS)
Tarumi, Ryuichi; Matsuhisa, Tomohiro; Shibutani, Yoji
2012-07-01
The complete sets of elastic constants Cij and piezoelectric coefficients eij for LiNbO3 and LiTaO3 single crystals have been determined by resonant ultrasound spectroscopy (RUS) from ambient temperature to 6 K. Both Cij(T) and eij(T) of the two crystals monotonically increased as the temperature decreased. The Einstein temperature estimated from Varshni's equation revealed that e15 and e22 of LiNbO3 have remarkably low values compared with the acoustic Debye temperature. In addition, the lattice anharmonicity of these piezoelectric coefficients was also extraordinarily low. An analysis based on the group theory and lattice dynamics revealed that both LiNbO3 and LiTaO3 crystals have three types of internal displacement modes: A1, A2, and E, and only the E mode affects e15 and e22. Therefore, it is reasonable to suppose that the E mode internal displacement is responsible for the unusual behaviors of the tow piezoelectric coefficients.
Guang, Jie; Hopson, Russell; Williard, Paul G
2015-09-18
We report extension of the D-FW analysis using referenced (2)H DOSY. This technique was developed in response to limitations due to peak overlay in (1)H DOSY spectra. We find a corresponding linear relationship (R(2) > 0.99) between log D and log FW as the basis of the D-FW analysis. The solution-state structure of THF solvated lithium diisopropyl amide (LDA) in hydrocarbon solvent was chosen to demonstrate the reliability of the methodology. We observe an equilibrium between monosolvated and disolvated dimeric LDA complexes at room temperature. Additionally we demonstrate the application of the (2)H D-FW analysis using a compound with an exchangeable proton that is readily labeled with (2)H. Hence, the (2)H DOSY D-FW analysis is shown to provide results consistent with the (1)H DOSY method, thereby greatly extending the applicability of the D-FW analysis. PMID:26318438
Kaplan, D
2005-08-31
The purpose of this document is to provide a technically defensible list of distribution coefficients, or Kd values, for use in performance assessment (PA) and special analysis (SA) calculations on the SRS. Only Kd values for radionuclides that have new information related to them or that have recently been recognized as being important are discussed in this report. Some 150 Kd values are provided in this report for various waste-disposal or tank-closure environments: soil, corrosion in grout, oxidizing grout waste, gravel, clay, and reducing concrete environments. Documentation and justification for the selection of each Kd value is provided.
Efficient path-based computations on pedigree graphs with compact encodings
2012-01-01
A pedigree is a diagram of family relationships, and it is often used to determine the mode of inheritance (dominant, recessive, etc.) of genetic diseases. Along with rapidly growing knowledge of genetics and accumulation of genealogy information, pedigree data is becoming increasingly important. In large pedigree graphs, path-based methods for efficiently computing genealogical measurements, such as inbreeding and kinship coefficients of individuals, depend on efficient identification and processing of paths. In this paper, we propose a new compact path encoding scheme on large pedigrees, accompanied by an efficient algorithm for identifying paths. We demonstrate the utilization of our proposed method by applying it to the inbreeding coefficient computation. We present time and space complexity analysis, and also manifest the efficiency of our method for evaluating inbreeding coefficients as compared to previous methods by experimental results using pedigree graphs with real and synthetic data. Both theoretical and experimental results demonstrate that our method is more scalable and efficient than previous methods in terms of time and space requirements. PMID:22536898
2012-05-11
The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less
Moody, A.
2012-05-11
The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.
Arithmetic area for m planar Brownian paths
NASA Astrophysics Data System (ADS)
Desbois, Jean; Ouvry, Stéphane
2012-05-01
We pursue the analysis made in Desbois and Ouvry (2011 J. Stat. Mech. P05024) on the arithmetic area enclosed by m closed Brownian paths. We pay particular attention to the random variable Sn1, n2,..., nm(m), which is the arithmetic area of the set of points, also called winding sectors, enclosed n1 times by path 1, n2 times by path 2,..., and nm times by path m. Various results are obtained in the asymptotic limit m\\to \\infty . A key observation is that, since the paths are independent, one can use in the m-path case the SLE information, valid in the one-path case, on the zero-winding sectors arithmetic area.
Mechanics of the crack path formation
NASA Technical Reports Server (NTRS)
Rubinstein, Asher A.
1991-01-01
A detailed analysis of experimentally obtained curvilinear crack path trajectories formed in a heterogeneous stress field is presented. Experimental crack path trajectories were used as data for the numerical simulations, recreating the actual stress field governing the development of the crack path. Thus, the current theories of crack curving and kinking could be examined by comparing them with the actual stress field parameters as they develop along the experimentally observed crack path. The experimental curvilinear crack path trajectories were formed in the tensile specimens with a hole positioned in the vicinity of a potential crack path. The numerical simulation, based on the solution of equivalent boundary value problems with the possible perturbations of the crack path, is presented.
Mechanics of the crack path formation
NASA Technical Reports Server (NTRS)
Rubinstein, Asher A.
1989-01-01
A detailed analysis of experimentally obtained curvilinear crack path trajectories formed in a heterogeneous stress field is presented. Experimental crack path trajectories were used as data for numerical simulations, recreating the actual stress field governing the development of the crack path. Thus, the current theories of crack curving and kinking could be examined by comparing them with the actual stress field parameters as they develop along the experimentally observed crack path. The experimental curvilinear crack path trajectories were formed in the tensile specimens with a hole positioned in the vicinity of a potential crack path. The numerical simulation, based on the solution of equivalent boundary value problems with the possible perturbations of the crack path, is presented here.
Coefficients for Interrater Agreement.
ERIC Educational Resources Information Center
Zegers, Frits E.
1991-01-01
The degree of agreement between two raters rating several objects for a single characteristic can be expressed through an association coefficient, such as the Pearson product-moment correlation. How to select an appropriate association coefficient, and the desirable properties and uses of a class of such coefficients--the Euclidean…
NASA Astrophysics Data System (ADS)
Zamani, K.; Bombardelli, F. A.
2014-12-01
Verification of geophysics codes is imperative to avoid serious academic as well as practical consequences. In case that access to any given source code is not possible, the Method of Manufactured Solution (MMS) cannot be employed in code verification. In contrast, employing the Method of Exact Solution (MES) has several practical advantages. In this research, we first provide four new one-dimensional analytical solutions designed for code verification; these solutions are able to uncover the particular imperfections of the Advection-diffusion-reaction equation, such as nonlinear advection, diffusion or source terms, as well as non-constant coefficient equations. After that, we provide a solution of Burgers' equation in a novel setup. Proposed solutions satisfy the continuity of mass for the ambient flow, which is a crucial factor for coupled hydrodynamics-transport solvers. Then, we use the derived analytical solutions for code verification. To clarify gray-literature issues in the verification of transport codes, we designed a comprehensive test suite to uncover any imperfection in transport solvers via a hierarchical increase in the level of tests' complexity. The test suite includes hundreds of unit tests and system tests to check vis-a-vis the portions of the code. Examples for checking the suite start by testing a simple case of unidirectional advection; then, bidirectional advection and tidal flow and build up to nonlinear cases. We design tests to check nonlinearity in velocity, dispersivity and reactions. The concealing effect of scales (Peclet and Damkohler numbers) on the mesh-convergence study and appropriate remedies are also discussed. For the cases in which the appropriate benchmarks for mesh convergence study are not available, we utilize symmetry. Auxiliary subroutines for automation of the test suite and report generation are designed. All in all, the test package is not only a robust tool for code verification but it also provides comprehensive
Su, Fangchu; Chen, Lei; Huang, Tao; Cai, Yu-Dong
2016-01-01
Biologically, fruits are defined as seed-bearing reproductive structures in angiosperms that develop from the ovary. The fertilization, development and maturation of fruits are crucial for plant reproduction and are precisely regulated by intrinsic genetic regulatory factors. In this study, we used Arabidopsis thaliana as a model organism and attempted to identify novel genes related to fruit-associated biological processes. Specifically, using validated genes, we applied a shortest-path-based method to identify several novel genes in a large network constructed using the protein-protein interactions observed in Arabidopsis thaliana. The described analyses indicate that several of the discovered genes are associated with fruit fertilization, development and maturation in Arabidopsis thaliana. PMID:27434024
Wang, Yong-Yan; Yang, Hong-Jun
2014-03-01
Small and medium-sized enterprises (SMEs) are important components in Chinese medicine industry. However, the lack of big brand is becoming an urgent problem which is critical to the survival of SMEs. This article discusses the concept and traits of Chinese medicine of big brand, from clinical, scientific and market value three aspects. Guided by market value, highlighting clinical value, aiming at the scientific value improvement of big brand cultivation, we put forward the key points in cultivation, aiming at obtaining branded Chinese medicine with widely recognized efficacy, good quality control system and mechanism well explained and meanwhile which can bring innovation improvement to theory of Chinese medicine. According to the characters of SMEs, we hold a view that to build multidisciplinary research union could be considered as basic path, and then, from top-level design, skill upgrading and application three stages to probe the implementation strategy. PMID:25204160
Summation Paths in Clenshaw-Curtis Quadrature
NASA Astrophysics Data System (ADS)
Adam, S.; Adam, Gh.
2016-02-01
Two topics concerning the use of Clenshaw-Curtis quadrature within the Bayesian automatic adaptive quadrature approach to the numerical solution of Riemann integrals are considered. First, it is found that the efficient floating point computation of the coefficients of the Chebyshev series expansion of the integrand is to be done within a mathematical structure consisting of the union of coefficient families ordered into complete binary trees. Second, the scrutiny of the decay rates of the involved even and odd rank Chebyshev expansion coefficients with the increase of their rank labels enables the definition of Bayesian decision paths for the advancement to the numerical output.
NASA Astrophysics Data System (ADS)
Qian, Z.; Hanasaki, N.; Fujimori, S.; Masaki, Y.; Hijioka, Y.
2015-12-01
Currently, hydropower accounts for 16% of the worldwide electricity power supply and 86% of the total renewable electricity energy source due to its low cost, low greenhouse gas (GHG) emission, and relatively high reliability. It is well known that the global hydropower has not yet been fully developed, but the future paths of development and corresponding contribution to GHG mitigation in each region combined with socioeconomic activities are less known. Here we investigated following three questions. How much will hydropower generation increase in the future? Will hydropower generation reach the economically exploitable capability (EEC)? If this will be the case, when and where will it occur? How much GHG emission will be reduced by adding new hydropower? In order to address these questions, we used the AIM/CGE model, a dynamic computable general equilibrium model to quantify the global hydropower development paths and corresponding GHG mitigation contribution for 17 regions in the world associated with a socio-economic scenario termed SSP2. We compared two scenarios with different assumptions on EEC. One is BAU which takes EEC from the report of "World Energy Resources", the other is FIX_BAU which fix EEC at the current hydropower generation amount throughout the research period (2005-2100) or no additional installation of hydropower plants. The comparison between two scenarios indicated that promoting hydropower development contributed to GHG emission reduction globally but the magnitude varied by region. For example we found that in North Africa, hydropower development grew fast because of the rapid economic development, but it reached EEC as soon as in 2040 because of limitation in EEC due to its climatic and geographical conditions. Conversely, in Brazil, it grew steadily and did not reach its abundant EEC. Consequently, GHG mitigation contribution of North Africa is far less than Brazil. This research provides important information for policy makers to
Wardell, Jeffrey D; Read, Jennifer P; Colder, Craig R; Merrill, Jennifer E
2012-04-01
Gray's (1975, 1987) behavioral activation (BAS) and behavioral inhibition systems (BIS) are thought to underlie sensitivity to reinforcement and punishment, respectively. Consistent with Gray's theory and the Acquired Preparedness model, BAS may facilitate the learning of positive alcohol expectancies (PAEs) over time, leading to increases in drinking. Yet, no prospective tests of this pathway have been reported. The present study investigated whether BAS prospectively predicted PAEs and whether PAEs mediated the association between BAS and subsequent alcohol use. We hypothesized that BAS would influence drinking specifically via enhancement-related PAEs. We also explored the role of BIS in PAEs and drinking. College students (N=557) completed online BAS, PAE, and alcohol use measures in September of their first (T1), second (T2), and third (T3) years of college. We conducted autoregressive path analyses with three BAS subscales and BIS (T1) as predictors, four PAE types (T2) as mediators, and quantity and frequency of drinking (T3) as outcomes. The BAS Fun-Seeking scale was prospectively associated with PAEs, and there was a significant indirect path from Fun-Seeking to alcohol use mediated specifically through activity enhancement PAEs. BIS was positively associated with some PAE types, but did not have indirect effects on drinking. Findings are consistent with both the theory of the BAS and the Acquired Preparedness model, as individuals high on BAS Fun-Seeking may find the rewarding properties of alcohol more reinforcing, leading to stronger enhancement PAEs and increased drinking over time. The prospective design helps establish the temporal association between BAS and alcohol-related learning, and points to the need for prevention efforts that target these at-risk students. PMID:22209025
Wardell, Jeffrey D.; Read, Jennifer P.; Colder, Craig R.; Merrill, Jennifer E.
2012-01-01
Gray’s (1975, 1987) behavioral activation (BAS) and behavioral inhibition systems (BIS) are thought to underlie sensitivity to reinforcement and punishment, respectively. Consistent with Gray’s theory and the Acquired Preparedness model, BAS may facilitate the learning of positive alcohol expectancies (PAEs) over time, leading to increases in drinking. Yet, no prospective tests of this pathway have been reported. The present study investigated whether BAS prospectively predicted PAEs and whether PAEs mediated the association between BAS and subsequent alcohol use. We hypothesized that BAS would influence drinking specifically via enhancement-related PAEs. We also explored the role of BIS in PAEs and drinking. College students (N=557) completed online BAS, PAE, and alcohol use measures in September of their first (T1), second (T2), and third (T3) years of college. We conducted autoregressive path analyses with three BAS subscales and BIS (T1) as predictors, four PAE types (T2) as mediators, and quantity and frequency of drinking (T3) as outcomes. The BAS Fun-Seeking scale was prospectively associated with PAEs, and there was a significant indirect path from Fun-Seeking to alcohol use mediated specifically through activity enhancement PAEs. BIS was positively associated with some PAE types, but did not have indirect effects on drinking. Findings are consistent with both the theory of the BAS and the Acquired Preparedness model, as individuals high on BAS Fun-Seeking may find the rewarding properties of alcohol more reinforcing, leading to stronger enhancement PAEs and increased drinking over time. The prospective design helps establish the temporal association between BAS and alcohol-related learning, and points to the need for prevention efforts that target these at-risk students. PMID:22209025
ERIC Educational Resources Information Center
Finch, Holmes
2010-01-01
Discriminant Analysis (DA) is a tool commonly used for differentiating among 2 or more groups based on 2 or more predictor variables. DA works by finding 1 or more linear combinations of the predictors that yield maximal difference among the groups. One common goal of researchers using DA is to characterize the nature of group difference by…
ERIC Educational Resources Information Center
Tracz, Susan M.; Elmore, Patricia B.
Meta-analysis is a technique for combining the summary statistics from previously conducted research studies to indicate the direction of results and provide an index of the magnitude of effect size. This paper focuses on the effect of the violation of the assumption of independence (that the value of any included statistic is in no way…
Kassab, Salah Eldin; Al-Shafei, Ahmad I; Salem, Abdel Halim; Otoom, Sameer
2015-01-01
Purpose This study examined the relationships between the different aspects of students’ course experience, self-regulated learning, and academic achievement of medical students in a blended learning curriculum. Methods Perceptions of medical students (n=171) from the Royal College of Surgeons in Ireland, Medical University of Bahrain (RCSI Bahrain), on the blended learning experience were measured using the Student Course Experience Questionnaire (SCEQ), with an added e-Learning scale. In addition, self-regulated learning was measured using the Motivated Strategies for Learning Questionnaire (MSLQ). Academic achievement was measured by the scores of the students at the end of the course. A path analysis was created to test the relationships between the different study variables. Results Path analysis indicated that the perceived quality of the face-to-face component of the blended experience directly affected the motivation of students. The SCEQ scale “quality of teaching” directly affected two aspects of motivation: control of learning and intrinsic goal orientation. Furthermore, appropriate course workload directly affected the self-efficacy of students. Moreover, the e-Learning scale directly affected students’ peer learning and critical thinking but indirectly affected metacognitive regulation. The resource management regulation strategies, time and study environment, and effort regulation directly affected students’ examination scores (17% of the variance explained). However, there were no significant direct relationships between the SCEQ scales and cognitive learning strategies or examination scores. Conclusion The results of this study will have important implications for designing blended learning courses in medical schools. PMID:25610011
Shirvani, Zeinab Gholamnia; Ghofranipour, Fazlollah; Gharakhanlou, Reza; Kazemnejad, Anoshirvan
2015-01-01
Level of physical activity as a key determinant of healthy lifestyle less than is required in individuals particularly women. Applying theories of behavioral change about complex behaviors such as physical activity leads to identify effective factors and their relations. The aim of this study was to determine predictors of physical activity behavior based on the Theory of Planned Behavior in military staff’s wives in Tehran. This cross-sectional study was performed in 180 military personnel’s spouses residing in organizational houses, in Tehran, Iran in 2014. The participants were randomly selected with multi-stage cluster sampling. The validity and reliability of the theory based scale evaluated before conducting the path analysis. Statistical analysis was carried out using SPSS16 and LISREL8.8. The results indicated the model explained 77% and 17% of intention and behavior variance. Subjective norms (Beta=0.83) and intention (Beta=0.37) were the strongest predictors of intention and behavior, respectively. The instrumental and affective attitude had no significant path to intention and behavior. The direct relation of perceived behavioral control to behavior was non-significant. This research demonstrated relative importance and relationships of Theory of Planned Behavior constructs in physical activity behavior of military personnel’s spouses in Tehran. It is essential to consider these determinants in designing of educational interventions for promoting and maintaining physical activity behavior in this target group. PMID:25948459
NASA Astrophysics Data System (ADS)
Lewandowska, Monika; Herzog, Robert; Malinowski, Leszek
2015-01-01
A heat slug propagation experiment in the final design dual channel ITER TF CICC was performed in the SULTAN test facility at EPFL-CRPP in Villigen PSI. We analyzed the data resulting from this experiment to determine the equivalent transverse heat transfer coefficient hBC between the bundle and the central channel of this cable. In the data analysis we used methods based on the analytical solutions of a problem of transient heat transfer in a dual-channel cable, similar to Renard et al. (2006) and Bottura et al. (2006). The observed experimental and other limits related to these methods are identified and possible modifications proposed. One result from our analysis is that the hBC values obtained with different methods differ by up to a factor of 2. We have also observed that the uncertainties of hBC in both methods considered are much larger than those reported earlier.
On the Feynman Path Integral for Nonrelativistic Quantum Electrodynamics
NASA Astrophysics Data System (ADS)
Ichinose, Wataru
The Feynman path integral for regularized nonrelativistic quantum electrodynamics is studied rigorously. We begin with the Lagrangian function of the corresponding classical mechanics and construct the Feynman path integral. In the present paper, the electromagnetic potentials are assumed to be periodic with respect to a large box and quantized through their Fourier coefficients with large wave numbers cut off. Firstly, the Feynman path integral with respect to paths on the space of particles and vector potentials is defined rigorously by means of broken line paths under the constraints. Secondly, the Feynman path integral with respect to paths on the space of particles and electromagnetic potentials is also defined rigorously by means of broken line paths and piecewise constant paths without the constraints. This Feynman path integral is stated heuristically in Feynman and Hibbs' book. Thirdly, the vacuum and the state of photons of given momenta and polarizations are expressed concretely as functions of variables consisting of the Fourier coefficients of vector potentials. It is also proved rigorously in terms of distribution theory that the Coulomb potentials between charged particles naturally appear in the above Feynman path integral approach. This shows that the photons give rise to the Coulomb force.
Diffusion and transport coefficients in synthetic opals
Sofo, J. O.; Mahan, G. D.
2000-07-15
Opals are structures composed of close-packed spheres in the size range of nano to micrometers. They are sintered to create small necks at the points of contact. We have solved the diffusion problem in such structures. The relation between the diffusion coefficient and the thermal and electrical conductivity is used to estimate the transport coefficients of opal structures as a function of the neck size and the mean free path of the carriers. The theory presented is also applicable to the diffusion problem in other periodic structures. (c) 2000 The American Physical Society.
NASA Astrophysics Data System (ADS)
Shin, Seungho; Kim, Ah-Reum; Um, Sukkee
2016-02-01
A two-dimensional material network model has been developed to visualize the nano-structures of fuel-cell catalysts and to search for effective transport paths for the optimal performance of fuel cells in randomly-disordered composite catalysts. Stochastic random modeling based on the Monte Carlo method is developed using random number generation processes over a catalyst layer domain at a 95% confidence level. After the post-determination process of the effective connectivity, particularly for mass transport, the effective catalyst utilization factors are introduced to determine the extent of catalyst utilization in the fuel cells. The results show that the superficial pore volume fractions of 600 trials approximate a normal distribution curve with a mean of 0.5. In contrast, the estimated volume fraction of effectively inter-connected void clusters ranges from 0.097 to 0.420, which is much smaller than the superficial porosity of 0.5 before the percolation process. Furthermore, the effective catalyst utilization factor is determined to be linearly proportional to the effective porosity. More importantly, this study reveals that the average catalyst utilization is less affected by the variations of the catalyst's particle size and the absolute catalyst loading at a fixed volume fraction of void spaces.
Effect of the shape on the spin state and exchange in quantum dots. Feynman path integral analysis
Shevkunov, S. V.
2015-05-15
The ab initio computer simulation of the mixed quantum states of 1–5-nm model ellipsoid quantum dots with “soft” walls containing two and three quantum-indistinguishable nonrelativistic electrons has been performed by the path integral method. The calculation has been carried out beyond the single-electron and mean-field approximations with the fundamentally exact inclusion of Coulomb and exchange correlations of all orders and the spin variable. Distributions over the eigenfunctions of the spin-squared operator, as well as the equilibrium spin numbers, have been obtained depending on the shape of a quantum dot and the temperature. The complete set of basis functions symmetrized in permutations according to the spin of the system has been obtained by application of the Young symmetry operators. The dependence of the energy on the shape of the quantum dot corresponds to the negative sign of the surface tension at its boundary. The calculation indicates that the spin magnetic susceptibility in the system of two electrons decreases strongly for spherical quantum dots (“pairing” of spins) and the temperature dependences have a pronounced maximum whose position depends on the shape of the quantum dot. For three electrons in an oblate quantum dot, the inversion of the energy levels of spin states is observed and affects the spin magnetic susceptibility. The results indicate a strong dependence of the energy of collective spin states of electrons on the detailed inclusion of exchange and Coulomb spatial correlations.
Li, Zheng; Huang, I-Chan; Thompson, Lindsay; Tuli, Sanjeev; Huang, Shih-Wen; DeWalt, Darren; Revicki, Dennis; Shenkman, Elizabeth
2013-01-01
Objectives We aimed to examine the relationships between asthma control, daytime sleepiness, and asthma-specific health-related quality of life (HRQOL) among children with asthma. Path analyses were conducted to test if daytime sleepiness can mediate the effect of asthma control status on asthma-specific HRQOL. Methods 160 dyads of asthmatic children and their parents were collected for analyses. The Asthma Control and Communication Instrument (ACCI) was used to categorize adequate and poor asthma control status. The Cleveland Adolescent Sleepiness Questionnaire (CASQ) was used to measure children’s daytime sleepiness, including sleep in school, awake in school, sleep in evening, and sleep during transport. The Patient-Reported Outcomes Measurement Information System (PROMIS) Asthma Impact Scale was used to measure asthma-specific HRQOL. Results Poorly controlled asthma was associated with daytime sleepiness and impaired asthma-specific HRQOL. Asthma control status was directly associated with asthma-specific HRQOL (P<.05), whereas sleep in school and sleep in evening domains of daytime sleepiness significantly mediated the relationship between poor asthma control and impaired HRQOL (P<.01). Conclusions Asthma control status was associated with pediatric asthma-specific HRQOL, and the association was significantly mediated by daytime sleepiness. Healthcare providers need to address pediatric sleep needs related to poor asthma control to reduce the impact on HRQOL. PMID:23684939
NASA Astrophysics Data System (ADS)
Chamssedine, F.; Sauvage, T.; Peuget, S.; Fares, T.; Martin, G.
2010-05-01
The immobilization of fission products and minor actinides by vitrification is the reference process for industrial management of high-level radioactive wastes generated by spent fuel reprocessing. Radiation damage and radiogenic helium accumulation must be specifically studied to evaluate the effects of minor actinide alpha decay on the glass long-term behavior under repository conditions. A specific experimental study was conducted for a comprehensive evaluation of the behavior of helium and its diffusion mechanisms in borosilicate nuclear waste glass. Helium production was simulated by external implantation with 3He ions at a concentration (≈1 at.%) 30 times higher than obtained after 10,000 years of storage. Helium diffusion coefficients as a function of temperature were extracted from the depth profiles after annealing. The 3He(d,α) 1H nuclear reaction analysis (NRA) technique was successfully adopted for low-temperature in situ measurements of depth profiles. Its high depth resolution revealed helium mobility at temperatures as low as 253 K and the presence of a trapped helium fraction. The diffusion coefficients of un-trapped helium atoms follow an Arrhenius law between 253 K and 323 K. An activation energy of 0.55 ± 0.03 eV was determined, which is consistent with a process controlled by diffusion in the glass free volume.
Devi, V M.; Benner, D C.; Smith, M.A.H.; Rinsland, Curtis P.; Sharpe, Steven W.; Sams, Robert L.
2004-09-01
High-resolution (0.005 cm-1) infrared absorption spectra of HCN in the 2v2 band region near 1411 cm-1 have been recorded at room temperature using the Bruker IFS120HR Fourier transform spectrometer located at Pacific Northwest National Laboratory. Four spectra of high-purity (99.8%) HCN together with three spectra of lean mixtures ({approx}3%) of HCN in dry air were simultaneously fit using a multispectrum non-linear least-squares procedure. The analysis yielded room temperature values for absolute intensities, self- and air-broadening coefficients, and self- and air-broadening coefficients for numerous lines in the 2v2 band of H13C14N, were also determined. Since there are no previous measurements of broadening and shift parameters reported in the 2v2 band, our results are compared with values recently determined in the v1 band of H13C14N and with current HITRAN values.
NASA Technical Reports Server (NTRS)
Chang, Y. V.
1986-01-01
The effects of external parameters on the surface heat and vapor fluxes into the marine atmospheric boundary layer (MABL) during cold-air outbreaks are investigated using the numerical model of Stage and Businger (1981a). These fluxes are nondimensionalized using the horizontal heat (g1) and vapor (g2) transfer coefficient method first suggested by Chou and Atlas (1982) and further formulated by Stage (1983a). In order to simplify the problem, the boundary layer is assumed to be well mixed and horizontally homogeneous, and to have linear shoreline soundings of equivalent potential temperature and mixing ratio. Modifications of initial surface flux estimates, time step limitation, and termination conditions are made to the MABL model to obtain accurate computations. The dependence of g1 and g2 in the cloud topped boundary layer on the external parameters (wind speed, divergence, sea surface temperature, radiative sky temperature, cloud top radiation cooling, and initial shoreline soundings of temperature, and mixing ratio) is studied by a sensitivity analysis, which shows that the uncertainties of horizontal transfer coefficients caused by changes in the parameters are reasonably small.
Marlar, Saw; Arnspang, Eva C; Pedersen, Gitte A; Koffman, Jennifer S; Nejsum, Lene N
2014-10-01
Micropatterning enabled semiquantitation of basolateral proteins in lateral and basal membranes of the same cell. Lateral diffusion coefficients of basolateral aquaporin-3 (AQP3-EGFP) and EGFP-AQP4 were extracted from "lateral" and "basal" membranes using identical live-cell imaging and k-space Image Correlation Spectroscopy (kICS). To simultaneously image proteins in "lateral" and "basal" membranes, micropatterning with the extracellular domain of E-cadherin and collagen, to mimic cell-cell and cell-extracellular matrix (ECM) adhesion, respectively, was used. In kidney collecting duct principal cells AQP3 localizes lateral and basal whereas AQP4 localizes mainly basal. On alternating stripes of E-cadherin and collagen, AQP3-EGFP was predominantly localized to "lateral" compared to "basal" membranes, whereas Orange-AQP4 was evenly distributed. Average diffusion coefficients were extracted via kICS analysis of rapid time-lapse sequences of AQP3-EGFP and EGFP-AQP4 on uniform substrates of either E-cadherin or collagen. AQP3-EGFP was measured to 0.022±0.010μm(2)/s on E-cadherin and 0.019±0.004μm(2)/s on collagen, whereas EGFP-AQP4 was measured to 0.044±0.009μm(2)/s on E-cadherin and 0.037±0.009μm(2)/s on collagen, thus, diffusion did not differ between substrates. Cholesterol depletion by methyl-beta-cyclodextrin (MBCD) reduced the AQP3-EGFP diffusion coefficient by 43% from 0.024±0.007μm(2)/s (water) to 0.014±0.003μm(2)/s (MBCD) (p<0.05) on collagen surfaces, and by 41% from 0.023±0.011μm(2)/s (water) to 0.014±0.005μm(2)/s (MBCD) (p<0.05) on E-cadherin surfaces. Thus, protein patterning enables the semiquantitation of protein distribution between the "lateral" and "basal" membranes as well as measurements of lateral diffusion coefficients. PMID:24950246
2013-01-01
The role of multilateral donor agencies in global health is a new area of research, with limited research on how these agencies differ in terms of their governance arrangements, especially in relation to transparency, inclusiveness, accountability, and responsiveness to civil society. We argue that historical analysis of the origins of these agencies and their coalition formation processes can help to explain these differences. We propose an analytical approach that links the theoretical literature discussing institutional origins to path dependency and institutional theory relating to proto institutions in order to illustrate the differences in coalition formation processes that shape governance within four multilateral agencies involved in global health. We find that two new multilateral donor agencies that were created by a diverse coalition of state and non-state actors, such as the Global Fund to Fight AIDS, Tuberculosis and Malaria and GAVI, what we call proto-institutions, were more adaptive in strengthening their governance processes. This contrasts with two well-established multilateral donor agencies, such as the World Bank and the Asian Development Bank, what we call Bretton Woods (BW) institutions, which were created by nation states alone; and hence, have different origins and consequently different path dependent processes. PMID:23663485
Gómez, Eduardo J; Atun, Rifat
2013-01-01
The role of multilateral donor agencies in global health is a new area of research, with limited research on how these agencies differ in terms of their governance arrangements, especially in relation to transparency, inclusiveness, accountability, and responsiveness to civil society. We argue that historical analysis of the origins of these agencies and their coalition formation processes can help to explain these differences. We propose an analytical approach that links the theoretical literature discussing institutional origins to path dependency and institutional theory relating to proto institutions in order to illustrate the differences in coalition formation processes that shape governance within four multilateral agencies involved in global health. We find that two new multilateral donor agencies that were created by a diverse coalition of state and non-state actors, such as the Global Fund to Fight AIDS, Tuberculosis and Malaria and GAVI, what we call proto-institutions, were more adaptive in strengthening their governance processes. This contrasts with two well-established multilateral donor agencies, such as the World Bank and the Asian Development Bank, what we call Bretton Woods (BW) institutions, which were created by nation states alone; and hence, have different origins and consequently different path dependent processes. PMID:23663485
NASA Technical Reports Server (NTRS)
Horton, Kent; Huffman, Mitch; Eppic, Brian; White, Harrison
2005-01-01
Path Loss Measurements were obtained on three (3) GPS equipped 757 aircraft. Systems measured were Marker Beacon, LOC, VOR, VHF (3), Glide Slope, ATC (2), DME (2), TCAS, and GPS. This data will provide the basis for assessing the EMI (Electromagnetic Interference) safety margins of comm/nav (communication and navigation) systems to portable electronic device emissions. These Portable Electronic Devices (PEDs) include all devices operated in or around the aircraft by crews, passengers, servicing personnel, as well as the general public in the airport terminals. EMI assessment capability is an important step in determining if one system-wide PED EMI policy is appropriate. This data may also be used comparatively with theoretical analysis and computer modeling data sponsored by NASA Langley Research Center and others.
NASA Astrophysics Data System (ADS)
Gosset, Dominique; Trocellier, Patrick; Serruys, Yves
2002-06-01
Host matrices for actinide immobilisation will undergo the formation of large helium quantities due to alpha decay. Helium diffusion rate has to be known in order to predict the long-term behaviour of the material, and particularly, the influence of helium accumulation on mechanical properties. A nuclear reaction analysis method, namely the 3He(d, p) 4He reaction, has been used to analyse the evolution of 3He profiles after ion implantations at 1 and 3 MeV in two materials, monoclinic ZrO 2 (as a test material) and Ca 9Nd(PO 4) 5(SiO 4)F 1.5(OH) 0.5 britholite (envisaged for Am and Pu long-term storage). Two data processing methods are used: the classical excitation curve (proton yields versus deuteron energy) and second, the proton energy spectrum for a given deuteron energy. The characteristics of the 3He profiles (depth, width) obtained by both methods are compared to SRIM estimations. Their evolution during subsequent annealings allows an estimation of the helium diffusion rate in the britholite: D ( cm2/ s)=(2.5±1.5)×10 -4exp(-(1.07±0.03 eV)/ kT) in the temperature range 200-400 °C, in agreement with previous results on similar materials. Moreover, the shape of the proton energy spectra suggests channeling effects in britholite.
Alarcón, M; Plomin, R; Fulker, D W; Corley, R; DeFries, J C
1998-07-01
A parent-offspring multivariate conditional path model was fitted to specific cognitive abilities data from the Colorado Adoption Project (CAP) when the offspring were 12 years of age. The sample included 175 adoptees, 175 sets of adoptive parents, 175 biological mothers, 34 biological fathers, and 209 nonadopted children and their parents. Consistent with results obtained from multivariate genetic analyses of CAP data obtained at earlier ages, the effects of familial environmental transmission on individual differences in specific cognitive abilities were not significant. Assuming complete isomorphism (i.e., that the genetic and environmental etiologies of individual differences are the same) between the child and the adult measures, the heritability estimates for verbal, spatial, perceptual speed, and visual memory were .26, .35, .38, and .53, respectively. Although the heritability estimate for visual memory is somewhat higher than those for verbal, spatial, and perceptual speed abilities, these estimates are not significantly different. These estimates are higher than those obtained when the adoptees and controls were 4 years old (Rice et al., 1986, 1989); thus, heritabilities of specific cognitive abilities may increase as a function of cognitive development. Alternatively, genetic stability from childhood to adulthood may be greater from 12 years than from 4 years, which would be interpreted as greater heritability by the CAP parent-offspring design. The genetic correlations among the four measures were substantial, ranging from .27 between verbal and spatial abilities to .78 between spatial ability and perceptual speed. However, differences among these correlations are not significant, suggesting that their covariation may be due to general cognitive ability. Finally, estimates of bivariate-heritability indicate that on average about half of the phenotypic correlations among the four specific cognitive ability measures are due to genetic effects. PMID
NASA Astrophysics Data System (ADS)
Esfandiari, M.; Shirmardi, S. P.; Medhat, M. E.
2014-06-01
In this study, element analysis and the mass attenuation coefficient for matrixes of gold, bronze and water with various impurities and the concentrations of heavy metals (Cu, Mn, Pb and Zn) are evaluated and calculated by the MCNP simulation code for photons emitted from Barium-133, Americium-241 and sources with energies between 1 and 100 keV. The MCNP data are compared with the experimental data and WinXCom code simulated results by Medhat. The results showed that the obtained results of bronze and gold matrix are in good agreement with the other methods for energies above 40 and 60 keV, respectively. However for water matrixes with various impurities, there is a good agreement between the three methods MCNP, WinXCom and the experimental one in low and high energies.
NASA Astrophysics Data System (ADS)
Lloyd, Seth; Dreyer, Olaf
2016-02-01
Path integrals calculate probabilities by summing over classical configurations of variables such as fields, assigning each configuration a phase equal to the action of that configuration. This paper defines a universal path integral, which sums over all computable structures. This path integral contains as sub-integrals all possible computable path integrals, including those of field theory, the standard model of elementary particles, discrete models of quantum gravity, string theory, etc. The universal path integral possesses a well-defined measure that guarantees its finiteness. The probabilities for events corresponding to sub-integrals can be calculated using the method of decoherent histories. The universal path integral supports a quantum theory of the universe in which the world that we see around us arises out of the interference between all computable structures.
Li, Haochu; Chen, Xinguang; Yu, Bin
2016-06-01
HIV stigma is widely believed to be related to HIV disclosure. However, there is a dearth of studies examining the mechanisms that link stigma to disclosure. This is a specific study to assess the relationship between perceived stigma and HIV disclosure to casual sex partners based on a social cognitive theory. HIV+ men who have sex with men (MSM) from two US cities (N = 297) completed questionnaires administered using audio computer-assisted self-interviewing. Path modeling analysis was used to assess the theory-based structural relationships. Perceived stigma was negatively associated with attitudes, intention and behavior of HIV disclosure to casual sex partners. The association was fully mediated by disclosure appraisal, including disclosure outcome expectations, costs and self-efficacy. Findings of this study add new knowledge regarding HIV stigma and disclosure, and provide timely data supporting more effective behavioral interventions to encourage HIV disclosure among MSM. PMID:27009408
Li, Qian P; Hansell, Dennis A
2008-03-17
Currently, two common techniques for nanomolar-level phosphate measurements in seawater are magnesium-induced co-precipitation (MAGIC) and long-path liquid-waveguide capillary cell (LWCC) spectrophotometry. These techniques have been applied in the open ocean, and our understanding of phosphate distributions in oligotrophic subtropical gyres is based on those data. However, intercomparison of these methods has not previously been performed at nanomolar levels. Here, we report experimental results directly comparing the MAGIC and LWCC techniques. We also evaluated the impact of various commonly employed filters on phosphate determinations, as well as interferences from dissolved organic phosphorus (DOP) and arsenate. Our results find agreement between these methods at phosphate concentrations <100nM. We found that filter selection is important for accurate determinations of phosphate, and that DOP hydrolysis affects both techniques similarly. Finally, we demonstrate the advantage of combining MAGIC preconcentration and LWCC spectrophotometry for analysis of very low nanomolar concentrations. PMID:18298969
An Application of Calculus: Optimum Parabolic Path Problem
ERIC Educational Resources Information Center
Atasever, Merve; Pakdemirli, Mehmet; Yurtsever, Hasan Ali
2009-01-01
A practical and technological application of calculus problem is posed to motivate freshman students or junior high school students. A variable coefficient of friction is used in modelling air friction. The case in which the coefficient of friction is a decreasing function of altitude is considered. The optimum parabolic path for a flying object…
Ramakrishnan; Sadana
1998-12-15
The diffusion-limited binding kinetics of antigen (analyte) in solution to antibody (receptor) immobilized on a biosensor surface is analyzed within a fractal framework. Most of the data presented are adequately described by a single-fractal analysis. This was indicated by the regression analysis provided by Sigmaplot ("Scientific Graphing Procedure, User's Manual," Jandel Scientific, San Rafael, CA, 1993). A couple of examples of a dual-fractal analysis are also presented. It is of interest to note that the binding rate coefficient and the fractal dimension both exhibit changes in the same direction for the analyte-receptor systems analyzed. Binding rate coefficient expressions as a function of the fractal dimension developed for the analyte-receptor binding systems indicate the high sensitivity of the binding rate coefficient on the fractal dimension when both a single- and a dual-fractal analysis are used. For example, for a single-fractal analysis and for the binding of cell surface proteins from Helicobacter pylori strain in solution to sialyl-(alpha-2,3)-lactose-conjugated (20 mol%) polyacrylamide immobilized on a resonant mirror biosensor (S. Hirmo et al., Anal. Biochem. 257, 63, 1998), the order of dependence of the binding rate coefficient, k, on the fractal dimension, Df, was 14.15. The fractional order of dependence of the binding rate coefficient(s) on the fractal dimension(s) further reinforces the fractal nature of the system. The binding rate coefficient(s) expressions developed as a function of the fractal dimension(s) are of particular value since they provide a means to better control biosensor performance by linking it to the heterogeneity on the surface and further emphasize in a quantitative sense the importance of the nature of the surface in biosensor performance. Copyright 1998 Academic Press. PMID:9845690
Optical tomography with discretized path integral.
Yuan, Bingzhi; Tamaki, Toru; Kushida, Takahiro; Mukaigawa, Yasuhiro; Kubo, Hiroyuki; Raytchev, Bisser; Kaneda, Kazufumi
2015-07-01
We present a framework for optical tomography based on a path integral. Instead of directly solving the radiative transport equations, which have been widely used in optical tomography, we use a path integral that has been developed for rendering participating media based on the volume rendering equation in computer graphics. For a discretized two-dimensional layered grid, we develop an algorithm to estimate the extinction coefficients of each voxel with an interior point method. Numerical simulation results are shown to demonstrate that the proposed method works well. PMID:26839903
ERIC Educational Resources Information Center
Henseler, Jorg; Chin, Wynne W.
2010-01-01
In social and business sciences, the importance of the analysis of interaction effects between manifest as well as latent variables steadily increases. Researchers using partial least squares (PLS) to analyze interaction effects between latent variables need an overview of the available approaches as well as their suitability. This article…
NASA Technical Reports Server (NTRS)
Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.
2008-01-01
Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.
Coefficients of Effective Length.
ERIC Educational Resources Information Center
Edwards, Roger H.
1981-01-01
Under certain conditions, a validity Coefficient of Effective Length (CEL) can produce highly misleading results. A modified coefficent is suggested for use when empirical studies indicate that underlying assumptions have been violated. (Author/BW)
Orbital Path of the International Space Station
Astronauts Don Pettit, Andre Kuipers and Dan Burbank explain the orbital path of the International Space Station. Earth video credit: Image Science and Analysis Laboratory, NASA's Johnson Space Cen...
NASA Astrophysics Data System (ADS)
Eaton, William
2012-02-01
The transition path is the tiny fraction of an equilibrium molecular trajectory when a transition occurs by crossing the free energy barrier between two states. It is a uniquely single-molecule property, and has not yet been observed experimentally for any system in the condensed phase. The importance of the transition path in protein folding is that it contains all of the mechanistic information on how a protein folds. As a major step toward observing transition paths, we have determined the average transition-path time for a fast and a slow-folding protein from a photon-by-photon analysis of fluorescence trajectories in single-molecule FRET experiments. While the folding rate coefficients differ by 10,000-fold, surprisingly, the transition-path times differ by less than 5-fold, showing that a successful barrier crossing event takes almost the same time for a fast- and a slow-folding protein, i.e. almost the same time to fold when it actually happens.
Survival paths for reaction dynamics in fluctuating environments
NASA Astrophysics Data System (ADS)
Wang, Jin; Wolynes, Peter
1994-03-01
We study rate processes in general Gaussian fluctuating environments using a path integral formalism. We derive a variational equation for the dominant survival path when the fluctuations relax exponentially or according to a stretched exponential law. In the case of a slowly varying barrier, the equilibrium regression approximation which is used by Frauenfelder and coworkers emerges. In this approximation, the survival path follows the ordinary law of relaxation to equilibrium. If the rate coefficients vary rapidly with environmental variables, however, the dominant survival paths exhibit more complex behaviour. Many phenomena analogous to geometrical optics occur. These include reflection off of rapid variations in rate constant, as well as refraction, giving paths very different from the equilibrium relaxation properties. A model with a piece-wise linear rate exhibits the basic phenomena, and the survival path equation is exactly solved for the general stretched exponential relaxing environment.
Investigating bias in squared regression structure coefficients
Nimon, Kim F.; Zientek, Linda R.; Thompson, Bruce
2015-01-01
The importance of structure coefficients and analogs of regression weights for analysis within the general linear model (GLM) has been well-documented. The purpose of this study was to investigate bias in squared structure coefficients in the context of multiple regression and to determine if a formula that had been shown to correct for bias in squared Pearson correlation coefficients and coefficients of determination could be used to correct for bias in squared regression structure coefficients. Using data from a Monte Carlo simulation, this study found that squared regression structure coefficients corrected with Pratt's formula produced less biased estimates and might be more accurate and stable estimates of population squared regression structure coefficients than estimates with no such corrections. While our findings are in line with prior literature that identified multicollinearity as a predictor of bias in squared regression structure coefficients but not coefficients of determination, the findings from this study are unique in that the level of predictive power, number of predictors, and sample size were also observed to contribute bias in squared regression structure coefficients. PMID:26217273
Reynolds, Arthur J.; Ou, Suh-Ruu
2013-01-01
We investigated the contribution of five hypotheses to the estimated effects of preschool in the Child-Parent Centers on occupational prestige, felony arrest, and depressive symptoms in adulthood in the Chicago Longitudinal Study. An alternative-intervention, quasi-experimental design included over 1,400 low-income participants (93% of whom were black) who attended preschool for 1–2 years or the usual early educational intervention and were traced to age 24. LISREL analysis of five hypotheses (cognitive advantage, family support, school support, motivational advantage, and social adjustment) indicated that while each individually accounted for part of the estimated direct effect of preschool on adult well-being, the best-fitting model across outcomes included indicators of all five hypotheses. The full model completely accounted for the direct effect of preschool on occupational prestige and official felony arrest, and 79% on depression symptoms. Key mediators included cognitive skills at school entry, school quality in the elementary grades, juvenile arrest, and school completion. The identified processes may help establish, strengthen, and sustain effects in other programs and settings. PMID:21410923
ERIC Educational Resources Information Center
Stegemoller, William; Stegemoller, Rebecca
2004-01-01
The path taken and the turns made as a turtle traces a polygon are examined to discover an important theorem in geometry. A unique tool, the Angle Adder, is implemented in the investigation. (Contains 9 figures.)
Tortuous path chemical preconcentrator
Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Wheeler, David R.; Simonson, Robert J.
2010-09-21
A non-planar, tortuous path chemical preconcentrator has a high internal surface area having a heatable sorptive coating that can be used to selectively collect and concentrate one or more chemical species of interest from a fluid stream that can be rapidly released as a concentrated plug into an analytical or microanalytical chain for separation and detection. The non-planar chemical preconcentrator comprises a sorptive support structure having a tortuous flow path. The tortuosity provides repeated twists, turns, and bends to the flow, thereby increasing the interfacial contact between sample fluid stream and the sorptive material. The tortuous path also provides more opportunities for desorption and readsorption of volatile species. Further, the thermal efficiency of the tortuous path chemical preconcentrator is comparable or superior to the prior non-planar chemical preconcentrator. Finally, the tortuosity can be varied in different directions to optimize flow rates during the adsorption and desorption phases of operation of the preconcentrator.
NASA Technical Reports Server (NTRS)
Snyder, G. Jeffrey (Inventor)
2015-01-01
A high temperature Seebeck coefficient measurement apparatus and method with various features to minimize typical sources of errors is described. Common sources of temperature and voltage measurement errors which may impact accurate measurement are identified and reduced. Applying the identified principles, a high temperature Seebeck measurement apparatus and method employing a uniaxial, four-point geometry is described to operate from room temperature up to 1300K. These techniques for non-destructive Seebeck coefficient measurements are simple to operate, and are suitable for bulk samples with a broad range of physical types and shapes.
Molina, Kristine M.; Alegría, Margarita; Mahalingam, Ramaswami
2012-01-01
Background Few studies have examined the psychosocial mechanisms through which self-reported discrimination may influence the health status of Latinos. Purpose This study examined the mediating role of subjective social status in the US and psychological distress on the relation between everyday discrimination and self-rated physical health, and the moderating role of gender and ethnicity. Methods A US population-based sample of Latinos (N= 2,554) was drawn from the National Latino and Asian American Study. Respondents completed measures of everyday discrimination, subjective social status, psychological distress, and self-rated physical health. Results Path analysis revealed that among the total sample, subjective social status and psychological distress sequentially mediated the effect of everyday discrimination on self-rated physical health. Psychological distress was a more consistent mediator across Latino subgroups. Gender and ethnicity moderated the mediation model. Conclusions This study provides a systematic examination of how psychosocial mechanisms may operate differently or similarly across Latino subgroups. PMID:23054945
Bounding the Bogoliubov coefficients
Boonserm, Petarpa; Visser, Matt
2008-11-15
While over the last century or more considerable effort has been put into the problem of finding approximate solutions for wave equations in general, and quantum mechanical problems in particular, it appears that as yet relatively little work seems to have been put into the complementary problem of establishing rigourous bounds on the exact solutions. We have in mind either bounds on parametric amplification and the related quantum phenomenon of particle production (as encoded in the Bogoliubov coefficients), or bounds on transmission and reflection coefficients. Modifying and streamlining an approach developed by one of the present authors [M. Visser, Phys. Rev. A 59 (1999) 427-438, (arXiv:quant-ph/9901030)], we investigate this question by developing a formal but exact solution for the appropriate second-order linear ODE in terms of a time-ordered exponential of 2x2 matrices, then relating the Bogoliubov coefficients to certain invariants of this matrix. By bounding the matrix in an appropriate manner, we can thereby bound the Bogoliubov coefficients.
NASA Astrophysics Data System (ADS)
Huffman, H. Dale
Using the IMPROVE network aerosol data from rural or remote sites across the United States, the ratio of the optically measured light absorption coefficient ( σa) to the elemental carbon measured by Thermal/Optical Reflectance (TOR) analysis consistently indicates an absorption efficiency that is twice the accepted value of 10m 2g -1. Correlations between σa and the TOR carbon strongly suggest that the discrepancy is due to an underevaluation of light-absorbing carbon rather than to an overestimation of σa or a real, higher value of the absorption efficiency. In particular, past doubts about the accuracy and precision of the IMPROVE σa measurement are here shown to be unsupported by the IMPROVE data. The large empirical correction that is applied to this σa measurement, for multiple scattering effects due to filter mass loading, is given a new explanation as the effect of an increasing forward scattering fraction as sample thickness increases. The old explanation of shadowing by overlying particles in the sample is rejected as having just the opposite effect to that needed to explain the correction. The use of a diffuse source rather than a laser beam is indicated as a way to avoid the large empirical correction of σa. Modelling of the light absorption by TOR carbon measurements, at twelve remote sites over a wide portion of the western United States, suggests the following errors in the current interpretation of TOR analysis for these sites: (1) The pyrolysis correction, based upon optical reflectance monitoring, appears to be largely wrong; and (2) The carbon evolving between 450 and 550°C in a pure helium atmosphere, currently interpreted as organic and therefore non-light-absorbing, appears to be as strongly light-absorbing as elemental carbon. However, the present analysis indicates that for a large majority (˜90%) of samples the light-absorbing carbons, as reinterpreted herein, are not only measured accurately by TOR, they are also reasonably well
Soangra, Rahul; Lockhart, Thurmon E
2012-01-01
Prolonged standing has been associated with loss of balance, onset of low back pain symptoms and development of fatigue in lower extremity muscles in working populations. Although so far, it is unknown how individuals postural stability is affected by standing on rigid versus cushioned platform but many industries are opting for anti-fatigue mats at workstations to reduce fall and injury related socio-economic cost. The goal of this study is to test SATECH's anti-fatigue mat for its effects on postural stability. A pilot test with seven healthy subjects (2535 years old) has been conducted with a force plate to obtain kinetics of body when standing on two different platforms. The centers of pressure (COP) position of subjects were determined on rigid and anti-fatigue mats for quiet stance (each trial 60 seconds). In order to understand postural control along with dynamic or stochastic characteristics of the COP, stabilogram diffusion analysis (SDA) and Invariant density analysis methods are used. Subject specific patterns were seen in stabilogram diffusion plots and associated parameters in both conditions. We also found differences in some postural sway SDA parameters with anti-fatigue mats compared to rigid vinyl floor standing with open eyes condition. But no significant differences were found in sway IDA parameters. This work further provides insights whether anti fatigue mats can be helpful to workers involved with prolonged standing tasks. PMID:22846314
Sampling diffusive transition paths
F. Miller III, Thomas; Predescu, Cristian
2006-10-12
We address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with sampling infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with sampling the coarse features of long paths. The fine-features sampling stiffness is eliminated with the use of the fast sampling algorithm (FSA), and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S&S) algorithm. A key feature of the S&S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. We use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature.
Sampling diffusive transition paths.
Miller, Thomas F; Predescu, Cristian
2007-04-14
The authors address the problem of sampling double-ended diffusive paths. The ensemble of paths is expressed using a symmetric version of the Onsager-Machlup formula, which only requires evaluation of the force field and which, upon direct time discretization, gives rise to a symmetric integrator that is accurate to second order. Efficiently sampling this ensemble requires avoiding the well-known stiffness problem associated with the sampling of infinitesimal Brownian increments of the path, as well as a different type of stiffness associated with the sampling of the coarse features of long paths. The fine-feature sampling stiffness is eliminated with the use of the fast sampling algorithm, and the coarse-feature sampling stiffness is avoided by introducing the sliding and sampling (S&S) algorithm. A key feature of the S&S algorithm is that it enables massively parallel computers to sample diffusive trajectories that are long in time. The authors use the algorithm to sample the transition path ensemble for the structural interconversion of the 38-atom Lennard-Jones cluster at low temperature. PMID:17444696
Qian, Weixian; Zhou, Xiaojun; Lu, Yingcheng; Xu, Jiang
2015-09-15
Both the Jones and Mueller matrices encounter difficulties when physically modeling mixed materials or rough surfaces due to the complexity of light-matter interactions. To address these issues, we derived a matrix called the paths correlation matrix (PCM), which is a probabilistic mixture of Jones matrices of every light propagation path. Because PCM is related to actual light propagation paths, it is well suited for physical modeling. Experiments were performed, and the reflection PCM of a mixture of polypropylene and graphite was measured. The PCM of the mixed sample was accurately decomposed into pure polypropylene's single reflection, pure graphite's single reflection, and depolarization caused by multiple reflections, which is consistent with the theoretical derivation. Reflection parameters of rough surface can be calculated from PCM decomposition, and the results fit well with the theoretical calculations provided by the Fresnel equations. These theoretical and experimental analyses verify that PCM is an efficient way to physically model light-matter interactions. PMID:26371930
Mobile transporter path planning
NASA Technical Reports Server (NTRS)
Baffes, Paul; Wang, Lui
1990-01-01
The use of a genetic algorithm (GA) for solving the mobile transporter path planning problem is investigated. The mobile transporter is a traveling robotic vehicle proposed for the space station which must be able to reach any point of the structure autonomously. Elements of the genetic algorithm are explored in both a theoretical and experimental sense. Specifically, double crossover, greedy crossover, and tournament selection techniques are examined. Additionally, the use of local optimization techniques working in concert with the GA are also explored. Recent developments in genetic algorithm theory are shown to be particularly effective in a path planning problem domain, though problem areas can be cited which require more research.
Diffusion coefficients of energetic water group ions near Comet Giacobini-Zinner
NASA Astrophysics Data System (ADS)
Tan, L. C.; Mason, G. M.; Richardson, I. G.; Ipavich, F. M.
1993-03-01
Data from the ultralow-energy charge analyzer and energetic particle anisotropy spectrometer sensors, acquired when the ICE spacecraft flew past Comet Giacobini-Zinner on September 11, 1985, are combined, and a single, self-consistent analysis technique is applied to derive a single-particle spectrum from about 200 to 1600 km/s. This information, together with the deduced bulk flow speed of the ions, is used to calculate a parallel diffusion coefficient in the transition region downstream of the bow wave (2.3 +/- 0.5) x 10 exp 17 sq cm/s; the corresponding scattering mean free path is (6 +/- 1) x 10 exp 4 km. The parallel diffusion coefficient is found to depend on the collision frequency of water group ions with Alfven waves, which are assumed to be propagating parallel (antiparallel) to the magnetic field.
Diffusion coefficients of energetic water group ions near Comet Giacobini-Zinner
NASA Technical Reports Server (NTRS)
Tan, L. C.; Mason, G. M.; Richardson, I. G.; Ipavich, F. M.
1993-01-01
Data from the ultralow-energy charge analyzer and energetic particle anisotropy spectrometer sensors, acquired when the ICE spacecraft flew past Comet Giacobini-Zinner on September 11, 1985, are combined, and a single, self-consistent analysis technique is applied to derive a single-particle spectrum from about 200 to 1600 km/s. This information, together with the deduced bulk flow speed of the ions, is used to calculate a parallel diffusion coefficient in the transition region downstream of the bow wave (2.3 +/- 0.5) x 10 exp 17 sq cm/s; the corresponding scattering mean free path is (6 +/- 1) x 10 exp 4 km. The parallel diffusion coefficient is found to depend on the collision frequency of water group ions with Alfven waves, which are assumed to be propagating parallel (antiparallel) to the magnetic field.
NASA Astrophysics Data System (ADS)
Ehret, G.; Kiemle, C.; Wirth, M.; Amediek, A.; Fix, A.; Houweling, S.
2008-03-01
CO2, CH4, and N2O are recognised as the most important greenhouse gases, the concentrations of which increase rapidly through human activities. Space-borne integrated path differential absorption lidar allows global observations at day and night over land and water surfaces in all climates. In this study we investigate potential sources of measurement errors and compare them with the scientific requirements. Our simulations reveal that moderate-size instruments in terms of telescope aperture (0.5 1.5 m) and laser average power (0.4 4 W) potentially have a low random error of the greenhouse gas column which is 0.2% for CO2 and 0.4% for CH4 for soundings at 1.6 μm, 0.4% for CO2 at 2.1 μm, 0.6% for CH4 at 2.3 μm, and 0.3% for N2O at 3.9 μm. Coherent detection instruments are generally limited by speckle noise, while direct detection instruments suffer from high detector noise using current technology. The wavelength selection in the vicinity of the absorption line is critical as it controls the height region of highest sensitivity, the temperature cross-sensitivity, and the demands on frequency stability. For CO2, an error budget of 0.08% is derived from our analysis of the sources of systematic errors. Among them, the frequency stability of ± 0.3 MHz for the laser transmitter and spectral purity of 99.9% in conjunction with a narrow-band spectral filter of 1 GHz (FWHM) are identified to be challenging instrument requirements for a direct detection CO2 system operating at 1.6 μm.
Puckett, L.J.; Cowdery, T.K.; McMahon, P.B.; Tornes, L.H.; Stoner, J.D.
2002-01-01
A combination of chemical and dissolved gas analyses, chlorofluorocarbon age dating, and hydrologic measurements were used to determine the degree to which biogeochemical processes in a riparian wetland were responsible for removing NO3- from groundwaters discharging to the Otter Tail River in west central Minnesota. An analysis of river chemistry and flow data revealed that NO3- concentrations in the river increased in the lower half of the 8.3 km study reach as the result of groundwater discharge to the river. Groundwater head measurements along a study transect through the riparian wetland revealed a zone of groundwater discharge extending out under the river. On the basis of combined chemical, dissolved gas, age date, and hydrologic results, it was determined that water chemistry under the riparian wetland was controlled largely by upgradient groundwaters that followed flow paths up to 16 m deep and discharged under the wetland, creating a pattern of progressively older, more chemically reduced, low NO3- water the farther one progressed from the edge of the wetland toward the river. These findings pose challenges for researchers investigating biogeochemical processes in riparian buffer zones because the progressively older groundwaters entered the aquifer in earlier years when less NO3- fertilizer was being used. NO3- concentrations originally present in the groundwater had also decreased in the upgradient aquifer as a result of denitrification and progressively stronger reducing conditions there. The resulting pattern of decreasing NO3- concentrations across the riparian zone may be incorrectly interpreted as evidence of denitrification losses there instead of in the upgradient aquifer. Consequently, it is important to understand the hydrogeologic setting and age structure of the groundwaters being sampled in order to avgid misinterpreting biogeochemical processes in riparian zones.
Cui, Yinqiu; Lindo, John; Hughes, Cris E.; Johnson, Jesse W.; Hernandez, Alvaro G.; Kemp, Brian M.; Ma, Jian; Cunningham, Ryan; Petzelt, Barbara; Mitchell, Joycellyn; Archer, David; Cybulski, Jerome S.; Malhi, Ripan S.
2013-01-01
To gain a better understanding of North American population history, complete mitochondrial genomes (mitogenomes) were generated from four ancient and three living individuals of the northern Northwest Coast of North America, specifically the north coast of British Columbia, Canada, current home to the indigenous Tsimshian, Haida, and Nisga’a. The mitogenomes of all individuals were previously unknown and assigned to new sub-haplogroup designations D4h3a7, A2ag and A2ah. The analysis of mitogenomes allows for more detailed analyses of presumed ancestor–descendant relationships than sequencing only the HVSI region of the mitochondrial genome, a more traditional approach in local population studies. The results of this study provide contrasting examples of the evolution of Native American mitogenomes. Those belonging to sub-haplogroups A2ag and A2ah exhibit temporal continuity in this region for 5000 years up until the present day. Of possible associative significance is that archaeologically identified house structures in this region maintain similar characteristics for this same period of time, demonstrating cultural continuity in residence patterns. The individual dated to 6000 years before present (BP) exhibited a mitogenome belonging to sub-haplogroup D4h3a. This sub-haplogroup was earlier identified in the same general area at 10300 years BP on Prince of Wales Island, Alaska, and may have gone extinct, as it has not been observed in any living individuals of the Northwest Coast. The presented case studies demonstrate the different evolutionary paths of mitogenomes over time on the Northwest Coast. PMID:23843972
Jonsson, Frida; San Sebastian, Miguel; Strömsten, Lotta M. J.; Hammarström, Anne; Gustafsson, Per E.
2016-01-01
While research examining the health impact of early socioeconomic conditions suggests that effects may exist independently of or jointly with adult socioeconomic position, studies exploring other potential pathways are few. Following a chain of risk life course model, this prospective study seeks to examine whether pathways of occupational class as well as material and social adversities across the life course link socioeconomic disadvantage in adolescent to functional somatic symptoms in mid-adulthood. Applying path analysis, a multiple mediator model was assessed using prospective data collected during 26 years through the Northern Swedish Cohort. The sample contained 987 individuals residing in the municipality of Luleå, Sweden, who participated in questionnaire surveys at age 16, 21, 30 and 42. Socioeconomic conditions (high/low) in adolescence (age 16) were operationalized using the occupation of the parents, while occupational class in adulthood (manual/non-manual) was measured using the participant’s own occupation at age 21 and 30. The adversity measurements were constructed as separate age specific parcels at age 21 and 30. Social adversity included items pertaining to stressful life events that could potentially harm salient relationships, while material adversity was operationalized using items concerning unfavorable financial and material circumstances. Functional somatic symptoms at age 42 was a summary measure of self-reported physical symptoms, palpitation and sleeping difficulties that had occurred during the last 12 months. An association between socioeconomic conditions at age 16 and functional somatic symptoms at age 42 (r = 0.068) which was partially explained by people’s own occupational class at age 21 and then material as well as social adversity at age 30 was revealed. Rather than proposing a direct and independent health effect of the socioeconomic conditions of the family, the present study suggests that growing up in an unfavorable
NASA Astrophysics Data System (ADS)
Newman, P. J.; Davis, K.; Haq, S. S. B.; Ridgway, K.
2015-12-01
Glacial erosion can have an impact on the location and development of faults in mountain belts. The rapid removal and deposition of rock, in some cases, is thought to affect the initiation of slip on older fault structures, or cause the development of new structures within the older part of the wedge. We present cross-sectional data from both erosional and non-erosional sandbox models of Coulomb wedges in order to quantify the impact of localized erosion on the location of and slip on deformational structures, as well as the general path of material through a wedge. To do this, we employ Lagrangian particle tracking velocimetry (PTV) using the open-source Python PTV toolkit trackpy, among a suite of other data analysis tools. We are able to extract robust and reliable sets of particle trajectories from a series of images without the need for predefined markers or marker-beds, instead identifying and tracking natural variations in sand color as individual particles. By comparing the motion of particles in cross-section to the local surface topography over an entire experiment, we determine a high-resolution record of exhumation rates, in addition to simple uplift rates. These comparisons are further informed by the use of high-definition Eulerian particle image velocimetry (PIV), which provides quantitative data about the distribution of deformation and instantaneous material displacements throughout a cross-sectional view of a Coulomb wedge. This allows us to interpret these pathways in relation to the behavior of active structures and general wedge morphology. In our experiments, we observe that localized glacial erosion has an impact on material pathways, in the form of an increased rate of exhumation locally, more vertical trajectories towards surface below the zone of erosion, and reactivation of older structures to maintain force balance within the entire wedge.
Li, Yang-yang; Zhao, Kai; Ren, Jian-hua; Ding, Yan-ling; Wu, Li-li
2014-01-01
Soil salinity is a global problem, especially in developing countries, which affects the environment and productivity of agriculture areas. Salt has a significant effect on the complex dielectric constant of wet soil. However, there is no suitable model to describe the variation in the backscattering coefficient due to changes in soil salinity content. The purpose of this paper is to use backscattering models to understand behaviors of the backscattering coefficient in saline soils based on the analysis of its dielectric constant. The effects of moisture and salinity on the dielectric constant by combined Dobson mixing model and seawater dielectric constant model are analyzed, and the backscattering coefficient is then simulated using the AIEM. Simultaneously, laboratory measurements were performed on ground samples. The frequency effect of the laboratory results was not the same as the simulated results. The frequency dependence of the ionic conductivity of an electrolyte solution is influenced by the ion's components. Finally, the simulated backscattering coefficients measured from the dielectric constant with the AIEM were analyzed using the extracted backscattering coefficient from the RADARSAT-2 image. The results show that RADARSAT-2 is potentially able to measure soil salinity; however, the mixed pixel problem needs to be more thoroughly considered. PMID:25101317
Li, Yang-yang; Zhao, Kai; Ren, Jian-hua; Ding, Yan-ling; Wu, Li-li
2014-01-01
Soil salinity is a global problem, especially in developing countries, which affects the environment and productivity of agriculture areas. Salt has a significant effect on the complex dielectric constant of wet soil. However, there is no suitable model to describe the variation in the backscattering coefficient due to changes in soil salinity content. The purpose of this paper is to use backscattering models to understand behaviors of the backscattering coefficient in saline soils based on the analysis of its dielectric constant. The effects of moisture and salinity on the dielectric constant by combined Dobson mixing model and seawater dielectric constant model are analyzed, and the backscattering coefficient is then simulated using the AIEM. Simultaneously, laboratory measurements were performed on ground samples. The frequency effect of the laboratory results was not the same as the simulated results. The frequency dependence of the ionic conductivity of an electrolyte solution is influenced by the ion's components. Finally, the simulated backscattering coefficients measured from the dielectric constant with the AIEM were analyzed using the extracted backscattering coefficient from the RADARSAT-2 image. The results show that RADARSAT-2 is potentially able to measure soil salinity; however, the mixed pixel problem needs to be more thoroughly considered. PMID:25101317
NASA Astrophysics Data System (ADS)
Artoun, Ojenie; David-Rus, Diana; Emmett, Matthew; Fishman, Lou; Fital, Sandra; Hogan, Chad; Lim, Jisun; Lushi, Enkeleida; Marinov, Vesselin
2006-05-01
In this report we summarize an extension of Fourier analysis for the solution of the wave equation with a non-constant coefficient corresponding to an inhomogeneous medium. The underlying physics of the problem is exploited to link pseudodifferential operators and phase space path integrals to obtain a marching algorithm that incorporates the backward scattering into the evolution of the wave. This allows us to successfully apply single-sweep, one-way marching methods in inherently two-way environments, which was not achieved before through other methods for this problem.
NASA Astrophysics Data System (ADS)
Vilhena de Moraes, Rodolpho; Cristiane Pardal, Paula; Koiti Kuga, Helio
The problem of orbit determination consists essentially of estimating parameter values that completely specify the body trajectory in the space, processing a set of information (measure-ments) from this body. Such observations can be collected through a conventional tracking network on Earth or through sensors like GPS. The Global Positioning System (GPS) is a powerful and low cost way to allow the computation of orbits for artificial Earth satellites. The Topex/Poseidon satellite is normally used as a reference for analyzing this system for space positioning. The orbit determination of artificial satellites is a nonlinear problem in which the disturbing forces are not easily modeled, like geopotential and direct solar radiation pressure. Through an onboard GPS receiver it is possible to obtain measurements (pseudo-range and phase) that can be used to estimate the state of the orbit. One intends to analyze the modeling of the orbit of an artificial satellite, using signals of the GPS constellation and least squares algorithms as a method of estimation, with the aim of analyzing the performance of the orbit estimation process. Accuracy is not the main goal; one pursues to verify how differences of modeling can affect the final accuracy of the orbit determination. To accomplish that, the following effects were considered: perturbations up to high degree and order for the geopoten-tial coefficients; direct solar radiation pressure, Sun attraction, and Moon attraction. It was also considered the position of the GPS antenna on the satellite body that, lately, consists of the influence of the satellite attitude motion in the orbit determination process. Although not presenting the ultimate accuracy, pseudo-range measurements corrected from ionospheric effects were considered enough to such analysis. The measurements were used to feed the batch least squares orbit determination process, in order to yield conclusive results about the orbit modeling issue. An application
Correlation between weighted spectral distribution and average path length in evolving networks.
Jiao, Bo; Shi, Jianmai; Wu, Xiaoqun; Nie, Yuanping; Huang, Chengdong; Du, Jing; Zhou, Ying; Guo, Ronghua; Tao, Yerong
2016-02-01
The weighted spectral distribution (WSD) is a metric defined on the normalized Laplacian spectrum. In this study, synchronic random graphs are first used to rigorously analyze the metric's scaling feature, which indicates that the metric grows sublinearly as the network size increases, and the metric's scaling feature is demonstrated to be common in networks with Gaussian, exponential, and power-law degree distributions. Furthermore, a deterministic model of diachronic graphs is developed to illustrate the correlation between the slope coefficient of the metric's asymptotic line and the average path length, and the similarities and differences between synchronic and diachronic random graphs are investigated to better understand the correlation. Finally, numerical analysis is presented based on simulated and real-world data of evolving networks, which shows that the ratio of the WSD to the network size is a good indicator of the average path length. PMID:26931591
Correlation between weighted spectral distribution and average path length in evolving networks
NASA Astrophysics Data System (ADS)
Jiao, Bo; Shi, Jianmai; Wu, Xiaoqun; Nie, Yuanping; Huang, Chengdong; Du, Jing; Zhou, Ying; Guo, Ronghua; Tao, Yerong
2016-02-01
The weighted spectral distribution (WSD) is a metric defined on the normalized Laplacian spectrum. In this study, synchronic random graphs are first used to rigorously analyze the metric's scaling feature, which indicates that the metric grows sublinearly as the network size increases, and the metric's scaling feature is demonstrated to be common in networks with Gaussian, exponential, and power-law degree distributions. Furthermore, a deterministic model of diachronic graphs is developed to illustrate the correlation between the slope coefficient of the metric's asymptotic line and the average path length, and the similarities and differences between synchronic and diachronic random graphs are investigated to better understand the correlation. Finally, numerical analysis is presented based on simulated and real-world data of evolving networks, which shows that the ratio of the WSD to the network size is a good indicator of the average path length.
Coherence-path duality relations for N paths
NASA Astrophysics Data System (ADS)
Hillery, Mark; Bagan, Emilio; Bergou, Janos; Cottrell, Seth
2016-05-01
For an interferometer with two paths, there is a relation between the information about which path the particle took and the visibility of the interference pattern at the output. The more path information we have, the smaller the visibility, and vice versa. We generalize this relation to a multi-path interferometer, and we substitute two recently defined measures of quantum coherence for the visibility, which results in two duality relations. The path information is provided by attaching a detector to each path. In the first relation, which uses an l1 measure of coherence, the path information is obtained by applying the minimum-error state discrimination procedure to the detector states. In the second, which employs an entropic measure of coherence, the path information is the mutual information between the detector states and the result of measuring them. Both approaches are quantitative versions of complementarity for N-path interferometers. Support provided by the John Templeton Foundation.
NASA Astrophysics Data System (ADS)
Haddag, B.; Atlati, S.; Nouari, M.; Zenasni, M.
2015-10-01
This paper deals with the modelling and identification of the heat exchange at the tool-workpiece interface in machining. A thermomechanical modelling has been established including heat balance equations of the tool-workpiece interface which take into account the heat generated by friction and the heat transfer by conduction due to the thermal contact resistance. The interface heat balance equations involve two coefficients: heat generation coefficient (HGC) of the frictional heat and heat transfer coefficient (HTC) of the heat conduction (inverse of the thermal contact resistance coefficient). Using experimental average heat flux in the tool, estimated for several cutting speeds, an identification procedure of the HGC-HTC couple, involved in the established thermomechanical FE-based modelling of the cutting process, has been proposed, which gives the numerical heat flux equal the measured one for each cutting speed. Using identified values of the HGC-HTC couple, evolution laws are proposed for the HGC as function of cutting speed, and then as function of sliding velocity at the tool-workpiece interface. Such laws can be implemented for instance in a Finite Element code for machining simulations.
NASA Astrophysics Data System (ADS)
Bakhshan, Younes; Omidvar, Alireza
2015-12-01
Micro scale gas flows have attracted significant research interest in the last two decades. In this research, the fluid flow of gases in a stepped micro-channel has been conducted. Wide range of Knudsen number has been implemented using the Lattice Boltzmann (MRT) method in this study. A modified second-order slip boundary condition and a Bosanquet-type effective viscosity are used to consider the velocity slip at the boundaries and to cover the slip and transition regimes of flow to obtain an accurate simulation of rarefied gases. The flow specifications such as pressure loss, velocity profile, stream lines and friction coefficient at different conditions have been presented. The results show, good agreement with available experimental data. The calculation shows, that the friction coefficient decreases with increasing the Knudsen number and stepping the micro-channel has an inverse effect on the friction coefficient value. Furthermore, a new correlation is suggested for calculation of the friction coefficient in the stepped micro-channel flows as below;
ERIC Educational Resources Information Center
Morgan, Paul L.; Sideridis, Georgios D.
2006-01-01
This study had two purposes. First, we sought to compare the overall effectiveness of different types of fluency interventions for students with learning disabilities (LD). Second, we attempted to identify how individual- and class-level characteristics moderated each intervention's effectiveness. We used multilevel random coefficient modeling to…
ERIC Educational Resources Information Center
Rodia, Becky
2004-01-01
This article profiles Diane Stanley, an author and illustrator of children's books. Although she was studying to be a medical illustrator in graduate school, Stanley's path changed when she got married and had children. As she was raising her children, she became increasingly enamored of the colorful children's books she would check out of the…
ERIC Educational Resources Information Center
McGarvey, Lynn M.; Sterenberg, Gladys Y.; Long, Julie S.
2013-01-01
The authors elucidate what they saw as three important challenges to overcome along the path to becoming elementary school mathematics teacher leaders: marginal interest in math, low self-confidence, and teaching in isolation. To illustrate how these challenges were mitigated, they focus on the stories of two elementary school teachers--Laura and…
Vorhees, C V; Weisenburger, W P; Acuff-Smith, K D; Minck, D R
1991-01-01
Three hypotheses on factors determining performance in a complex water maze were tested in rats prenatally exposed to phenytoin. The hypotheses were: 1) that increasing maze complexity would better differentiate experimental effects; in particular, that an expanded version of a maze originally described by Biel would better differentiate groups than Biel's original design; 2) that path order is an important factor determining performance; specifically, that path sequence AB would better differentiate experiments from controls than the opposite order (sequence BA); and 3) that repeated trial failures interfere with learning, a problem putatively prevented by employing assisted (i.e., guided) escape. The specific prediction was that rats tested with assisted escape would learn faster and produce better group differentiation than rats tested with unassisted escape. Pregnant female Sprague-Dawley CD rats were gavaged on days 7-18 of gestation with propylene glycol alone (Control) or containing 100 or 200 mg/kg of phenytoin. Straight channel swimming trials followed by maze trials were begun on separate male/female offspring pairs from each litter on postnatal days 50, 70, or 90. The results confirmed hypothesis 1, i.e., the more complex maze better differentiated phenytoin-related group differences. This was true regardless of whether the phenytoin rats exhibiting circling were included in the analyses or not. The results disconfirmed hypothesis 2, i.e., that path order AB would better differentiate the groups than path order BA. Rather, the data supported the alternate hypothesis, that path order was not a significant determinant of prenatal drug-related maze deficits. This was unchanged regardless of whether phenytoin offspring exhibiting circling were or were not included in the analyses. The implication is that path B alone was sufficient to detect phenytoin's effects on maze performance. Finally, the overall results disconfirmed hypothesis 3, i.e., assisted escape
Heindl, R.; Rippard, W. H.; Russek, S. E.; Pufall, M. R.
2014-12-28
We performed thousands of single-shot, real-time measurements of spin-transfer-torque induced switching in nanoscale CoFeB/MgO/CoFeB magnetic tunnel junctions having in-plane magnetizations. Our investigation discovered a variety of switching paths occurring in consecutive, nominally identical switching trials of a single device. By mapping the voltage as a function of time to an effective magnetization angle, we determined that reversal of a single device occurs via a variety of thermally activated paths. Our results show a complex switching behavior that has not been captured by previous observations and cannot be fully explained within the simple macrospin model.
Statistical Methods with Varying Coefficient Models
Fan, Jianqing; Zhang, Wenyang
2008-01-01
The varying coefficient models are very important tool to explore the dynamic pattern in many scientific areas, such as economics, finance, politics, epidemiology, medical science, ecology and so on. They are natural extensions of classical parametric models with good interpretability and are becoming more and more popular in data analysis. Thanks to their flexibility and interpretability, in the past ten years, the varying coefficient models have experienced deep and exciting developments on methodological, theoretical and applied sides. This paper gives a selective overview on the major methodological and theoretical developments on the varying coefficient models. PMID:18978950
Current SPE Hydrodynamic Modeling and Path Forward
Knight, Earl E.; Rougier, Esteban
2012-08-14
Extensive work has been conducted on SPE analysis efforts: Fault effects Non-uniform weathered layer analysis MUNROU: material library incorporation, parallelization, and development of non-locking tets Development of a unique continuum-based-visco-plastic strain-rate-dependent material model With corrected SPE data path is now set for a multipronged approach to fully understand experimental series shot effects.
On the orthogonalised reverse path method for nonlinear system identification
NASA Astrophysics Data System (ADS)
Muhamad, P.; Sims, N. D.; Worden, K.
2012-09-01
The problem of obtaining the underlying linear dynamic compliance matrix in the presence of nonlinearities in a general multi-degree-of-freedom (MDOF) system can be solved using the conditioned reverse path (CRP) method introduced by Richards and Singh (1998 Journal of Sound and Vibration, 213(4): pp. 673-708). The CRP method also provides a means of identifying the coefficients of any nonlinear terms which can be specified a priori in the candidate equations of motion. Although the CRP has proved extremely useful in the context of nonlinear system identification, it has a number of small issues associated with it. One of these issues is the fact that the nonlinear coefficients are actually returned in the form of spectra which need to be averaged over frequency in order to generate parameter estimates. The parameter spectra are typically polluted by artefacts from the identification of the underlying linear system which manifest themselves at the resonance and anti-resonance frequencies. A further problem is associated with the fact that the parameter estimates are extracted in a recursive fashion which leads to an accumulation of errors. The first minor objective of this paper is to suggest ways to alleviate these problems without major modification to the algorithm. The results are demonstrated on numerically-simulated responses from MDOF systems. In the second part of the paper, a more radical suggestion is made, to replace the conditioned spectral analysis (which is the basis of the CRP method) with an alternative time domain decorrelation method. The suggested approach - the orthogonalised reverse path (ORP) method - is illustrated here using data from simulated single-degree-of-freedom (SDOF) and MDOF systems.
NASA Astrophysics Data System (ADS)
Simeone, Emilio; Donati, Alessandro
1998-12-01
The increment of the exploitable optical path represents one of the most important efforts in the differential optical absorption spectroscopy (DOAS) instruments improvement. The methods that allow long path measurements in the UV region are presented and discussed in this paper. These methods have been experimented in the new Italian DOAS instrument - SPOT - developed and manufactured by Kayser Italia. The system was equipped with a tele-controlled optical shuttle on the light source unit, allowing background radiation measurement. Wavelength absolute calibration of spectra by means of a collimated UV beam from a mercury lamp integrated in the telescope has been exploited. Besides, possible thermal effects on the dispersion coefficients of the holographic grating have been automatically compensated by means of a general non-linear fit during the spectral analysis session. Measurements in bistatic configuration have been performed in urban areas at 1300 m and 2200 m in three spectral windows from 245 to 380 nm. Measurements with these features are expected in the other spectral windows on path lengths ranging from about 5 to 10 km in urban areas. The DOAS technique can be used in field for very fast measurements in the 245-275 nm spectral range, on path lengths up to about 2500 m.
Devi, V M.; Benner, D C.; Smith, M.A.H.; Rinsland, Curtis P.; Predoi-Cross, A; Sharpe, Steven W.; Sams, Robert L.; Boulet, C; Bouanich, J P.
2005-05-01
Absolute intensities, self- and air-broadening coefficients, self- and air-induced shift coefficients and their temperature dependences have been determined for lines belonging to the P- and R-branches of the {nu}{sub 2} band of H{sup 12}C{sup 14}N centered near 712 cm{sup -1}. Infrared spectra of HCN in the 14-{micro}m region were obtained at high resolution (0.002-0.008 cm{sup -1}) using two different Fourier transform spectrometers (FTS), the McMath-Pierce FTS at the National Solar Observatory on Kitt Peak and the Bruker IFS 120HR FTS at the Pacific Northwest National Laboratory. Spectra were recorded with 99.8% pure HCN as well as lean mixtures of HCN in air at various temperatures ranging between +26 C and -60 C. A multispectrum nonlinear least squares technique was used to fit selected intervals of 36 spectra simultaneously to obtain the line positions, intensities, broadening and shift parameters. The measured line intensities were analyzed to determine the vibrational band intensity and the Herman-Wallis coefficients. The measured self-broadening coefficients vary between 0.2 and 1.2 cm{sup -1} atm{sup -1} at 296 K, and the air broadening coefficients range from 0.08 to 0.14 cm{sup -1} atm{sup -1} at 296 K. The temperature dependence exponents of self-broadening range from 1.46 to -0.12 while the corresponding exponents for air broadening vary between 0.58 and 0.86. The present measurements are the first known determination of negative values for the temperature dependence exponents of HCN broadening coefficients. We were able to support our self-broadening measurements with appropriate theoretical calculations. Our present measurements are compared, where possible, with previous measurements for this and other HCN bands, as well as the parameters that are included in the 2000 and 2004 editions of the HITRAN (HIgh-resolution TRANsmission) database.
ERIC Educational Resources Information Center
Mapp, Susan C.
2006-01-01
Objective: The potential path from sexual abuse as a child to the current risk of physical abuse by mothers was assessed. Ontogenic variables including the experience of the parent's sexual abuse as a child and current depression or substance abuse were expected to have a greater impact on the risk of child abuse than microsystem and exosystem…
NASA Astrophysics Data System (ADS)
Vikas, Kumar; K. Gupta, R.; Ram, Jiwari
2014-03-01
In this paper, the variable-coefficient diffusion—advection (DA) equation, which arises in modeling various physical phenomena, is studied by the Lie symmetry approach. The similarity reductions are derived by determining the complete sets of point symmetries of this equation, and then exact and numerical solutions are reported for the reduced second-order nonlinear ordinary differential equations. Further, an extended (G'/G)-expansion method is applied to the DA equation to construct some new non-traveling wave solutions.
Khlebnikov, V.I.
1988-05-01
The problem of integration is discussed for a complete system of Newman-Penrose equations for electrovacuum spaces of the general theory of relativity with nonzero cosmological constant. In terms of the method of spin coefficients, we formulate conditions on the electormagnetic and gravitational field variables, which distinguish a special class of Riemann spaces corresponding to strong gravitational waves in semiclosed Universes of Bertotti-Robinson type.
Equivalence of trans paths in ion channels
NASA Astrophysics Data System (ADS)
Alvarez, Juan; Hajek, Bruce
2006-04-01
We explore stochastic models for the study of ion transport in biological cells. Analysis of these models explains and explores an interesting feature of ion transport observed by biophysicists. Namely, the average time it takes ions to cross certain ion channels is the same in either direction, even if there is an electric potential difference across the channels. It is shown for simple single ion models that the distribution of a path (i.e., the history of location versus time) of an ion crossing the channel in one direction has the same distribution as the time-reversed path of an ion crossing the channel in the reverse direction. Therefore, not only is the mean duration of these paths equal, but other measures, such as the variance of passage time or the mean time a path spends within a specified section of the channel, are also the same for both directions of traversal. The feature is also explored for channels with interacting ions. If a system of interacting ions is in reversible equilibrium (net flux is zero), then the equivalence of the left-to-right trans paths with the time-reversed right-to-left trans paths still holds. However, if the system is in equilibrium, but not reversible equilibrium, then such equivalence need not hold.
Cho, Jae Heon; Lee, Jong Ho
2015-11-01
Manual calibration is common in rainfall-runoff model applications. However, rainfall-runoff models include several complicated parameters; thus, significant time and effort are required to manually calibrate the parameters individually and repeatedly. Automatic calibration has relative merit regarding time efficiency and objectivity but shortcomings regarding understanding indigenous processes in the basin. In this study, a watershed model calibration framework was developed using an influence coefficient algorithm and genetic algorithm (WMCIG) to automatically calibrate the distributed models. The optimization problem used to minimize the sum of squares of the normalized residuals of the observed and predicted values was solved using a genetic algorithm (GA). The final model parameters were determined from the iteration with the smallest sum of squares of the normalized residuals of all iterations. The WMCIG was applied to a Gomakwoncheon watershed located in an area that presents a total maximum daily load (TMDL) in Korea. The proportion of urbanized area in this watershed is low, and the diffuse pollution loads of nutrients such as phosphorus are greater than the point-source pollution loads because of the concentration of rainfall that occurs during the summer. The pollution discharges from the watershed were estimated for each land-use type, and the seasonal variations of the pollution loads were analyzed. Consecutive flow measurement gauges have not been installed in this area, and it is difficult to survey the flow and water quality in this area during the frequent heavy rainfall that occurs during the wet season. The Hydrological Simulation Program-Fortran (HSPF) model was used to calculate the runoff flow and water quality in this basin. Using the water quality results, a load duration curve was constructed for the basin, the exceedance frequency of the water quality standard was calculated for each hydrologic condition class, and the percent reduction
Nonadiabatic transition path sampling
NASA Astrophysics Data System (ADS)
Sherman, M. C.; Corcelli, S. A.
2016-07-01
Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase.
Nonadiabatic transition path sampling.
Sherman, M C; Corcelli, S A
2016-07-21
Fewest-switches surface hopping (FSSH) is combined with transition path sampling (TPS) to produce a new method called nonadiabatic path sampling (NAPS). The NAPS method is validated on a model electron transfer system coupled to a Langevin bath. Numerically exact rate constants are computed using the reactive flux (RF) method over a broad range of solvent frictions that span from the energy diffusion (low friction) regime to the spatial diffusion (high friction) regime. The NAPS method is shown to quantitatively reproduce the RF benchmark rate constants over the full range of solvent friction. Integrating FSSH within the TPS framework expands the applicability of both approaches and creates a new method that will be helpful in determining detailed mechanisms for nonadiabatic reactions in the condensed-phase. PMID:27448877
Studness, C.M.
1995-05-01
The financial community`s focus on utility competition has been riveted on the proceedings now in progress at state regulatory commissions. The fear that something immediately damaging will come out of these proceedings seems to have diminished in recent months, and the stock market has reacted favorably. However, regulatory developments are only one of four paths leading to competition; the others are the marketplace, the legislatures, and the courts. Each could play a critical role in the emergence of competition.
PATHS groundwater hydrologic model
Nelson, R.W.; Schur, J.A.
1980-04-01
A preliminary evaluation capability for two-dimensional groundwater pollution problems was developed as part of the Transport Modeling Task for the Waste Isolation Safety Assessment Program (WISAP). Our approach was to use the data limitations as a guide in setting the level of modeling detail. PATHS Groundwater Hydrologic Model is the first level (simplest) idealized hybrid analytical/numerical model for two-dimensional, saturated groundwater flow and single component transport; homogeneous geology. This document consists of the description of the PATHS groundwater hydrologic model. The preliminary evaluation capability prepared for WISAP, including the enhancements that were made because of the authors' experience using the earlier capability is described. Appendixes A through D supplement the report as follows: complete derivations of the background equations are provided in Appendix A. Appendix B is a comprehensive set of instructions for users of PATHS. It is written for users who have little or no experience with computers. Appendix C is for the programmer. It contains information on how input parameters are passed between programs in the system. It also contains program listings and test case listing. Appendix D is a definition of terms.
NASA Technical Reports Server (NTRS)
2004-01-01
Scientists created this overlay map by laying navigation and panoramic camera images taken from the surface of Mars on top of one of Spirit's descent images taken as the spacecraft descended to the martian surface. The map was created to help track the path that Spirit has traveled through sol 44 and to put into perspective the distance left to travel before reaching the edge of the large crater nicknamed 'Bonneville.'
The area boxed in yellow contains the ground images that have been matched to and layered on top of the descent image. The yellow line shows the path that Spirit has traveled and the red dashed line shows the intended path for future sols. The blue circles highlight hollowed areas on the surface, such as Sleepy Hollow, near the lander, and Laguna Hollow, the sol 45 drive destination. Scientists use these hollowed areas - which can be seen in both the ground images and the descent image - to correctly match up the overlay.
Field geologists on Earth create maps like this to assist them in tracking their observations.
NASA Astrophysics Data System (ADS)
Ishii, K.; Fujita, A.; Toyama, S.; Terakawa, A.; Matsuyama, S.; Arai, H.; Osada, N.; Takyu, S.; Matsuyama, T.; Koshio, S.; Watanabe, K.; Ito, S.; Kasahara, K.
Edible wild plants growing in the area around the Fukushima Daiichi nuclear power plant remain contaminated. It is important to identify plants with low levels of contamination for the restoration of agriculture in the area. We collected specimens of 10 wild plant species growing in Iitate village which is one of the most highly contaminated areas and also sampled the soil beneath each plant. We measured the specific activity of 137Cs and the concentrations of Na, Mg, Al, Si, P, S, K, Ca, Fe, Zn, Rb and Sr in these samples using a germanium detector and PIXE analysis, respectively. We compared the soil-plant transfer coefficient of 137Cs with those of each element and determined their correlation with 137Cs. It was found that a low Sr transfer coefficient could be used to determine the plants with a low 137Cs transfer coefficient. We suggest that PIXE analysis is a useful analysis technique for agricultural remediation projects in highly contaminated areas around the Fukushima Daiichi nuclear power plant.
[A path-length correction method on biochemical parameter nondestructive measuring of folium].
Zhang, Qian-Xuan; Zhang, Guang-Jun; Li, Qing-Bo
2010-05-01
Vis/NIR spectroscopy technology is capable of analyzing the content of biochemical parameter in folium rapidly and nondestructively. In the process of spectrum analysis, the variations in path-length between different samples exist, with the random light scattering and leaf thickness perturbations, which influence the precision of quantitative analysis model. In order to resolve this problem, an improved path-length correction method based on Extended Multiplicative Scattering Correction is presented. In this paper, firstly the theory of EMSC algorithm is deduced. EMSC method incorporates both chemical terms and wavelength functions to help realize the efficient separation of path-length and interest concentration. Secondly two experiments were implemented to demonstrate the validity of the method. In Experiment 1, sixteen samples of different thickness but almost the same chlorophyll content were selected, and how the path-length affects the spectrum was compared, after EMSC preprocessing, the variable coefficient of spectrum could approach the repeatability error of spectrometer. In Experiment 2, thirty-two samples of different thickness and chlorophyll content were selected. PLS model established using cross validation was employed to evaluate the efficiency of the presented algorithm. Before the preprocessing, the root mean squared error of prediction is 3.9 SPAD with 5 principal components. After preprocessing, the predicted root mean squared error is 2.2 SPAD with 12 principal components. The results indicate that the improved EMSC preprocessing method could exactly eliminate the spectrum difference caused by the path-length variations between different foliums, enhance the sensitivity of concentration and spectral data, and increase the precision of calibrated model. PMID:20672624
Factors affecting miscible flooding dispersion coefficients
Yellig, W.F.; Baker, L.E.
1980-01-01
Miscible solvent slug size, and therefore cost, is dependent on the mixing or dispersion taking place in the reservoir. Fluid mixing also can be important in the interpretation of laboratory simulations of miscible floods. An experimental program was conducted to study the effects of velocity, viscosity ratio, rock type, and core length on dispersion (mixing) coefficients measured in short cores, with the objective of scaling laboratory measurements to field systems. Statistical analysis of the results of the tests, matched with the capacitance-dispersion (dead-end pore volume) model, shows that an effective dispersion coefficient derived from the model is the most consistent measure of mixing in the systems studied. Viscosity ratios differing by + 4% from unity had no significant effect on the effective dispersion coefficient. The effect of system length on the effective dispersion coefficient is shown.
Transonic Blunt Body Aerodynamic Coefficients Computation
NASA Astrophysics Data System (ADS)
Sancho, Jorge; Vargas, M.; Gonzalez, Ezequiel; Rodriguez, Manuel
2011-05-01
In the framework of EXPERT (European Experimental Re-entry Test-bed) accurate transonic aerodynamic coefficients are of paramount importance for the correct trajectory assessment and parachute deployment. A combined CFD (Computational Fluid Dynamics) modelling and experimental campaign strategy was selected to obtain accurate coefficients. A preliminary set of coefficients were obtained by CFD Euler inviscid computation. Then experimental campaign was performed at DNW facilities at NLR. A profound review of the CFD modelling was done lighten up by WTT results, aimed to obtain reliable values of the coefficients in the future (specially the pitching moment). Study includes different turbulence modelling and mesh sensitivity analysis. Comparison with the WTT results is explored, and lessons learnt are collected.
Second coefficient of viscosity in air
NASA Technical Reports Server (NTRS)
Ash, Robert L.; Zuckerwar, Allan J.; Zheng, Zhonquan
1991-01-01
Acoustic attenuation measurements in air were analyzed in order to estimate the second coefficient of viscosity. Data over a temperature range of 11 C to 50 C and at relative humidities between 6 percent and 91 percent were used. This analysis showed that the second coefficient of viscosity varied between 1900 and 20,000 times larger than the dynamic or first coefficient of viscosity over the temperature and humidity range of the data. In addition, the data showed that the molecular relaxation effects, which are responsible for the magnitude of the second coefficient of viscosity, place severe limits on the use of time-independent, thermodynamic equations of state. Compressible flows containing large streamwise velocity gradients, like shock waves, which cause significant changes in particle properties to occur during time intervals shorter than hundredths of seconds, must be modeled using dynamic equations of state. The dynamic model approach is described briefly.
Uzhegov, V.N.; Kozlov, V.S.; Panchenko, M.V.; Pkhalagov, Yu.A.; Pol'kin, V.V.; Terpugova, S.A.; Shmargunov, V.P.; Yausheva, E.P.
2005-03-18
The problem of the choice of the aerosol optical constants and, in particular, imaginary part of the refractive index of particles in visible and infrared (IR) wavelength ranges is very important for calculation of the global albedo of the atmosphere in climatic models. The available models of the aerosol optical constants obtained for the prescribed chemical composition of particles (see, for example, Ivlev et al. 1973; Ivlev 1982; Volz 1972), often are far from real aerosol. It is shown in (Krekov et al. 1982) that model estimates of the optical characteristics of the atmosphere depending on the correctness of real and imaginary parts of the aerosol complex refractive index can differ by some hundreds percent. It is known that the aerosol extinction coefficient {alpha}({lambda}) obtained from measurements on a long horizontal path can be represented as {alpha}({lambda})={sigma}({lambda})+{beta}({lambda}), where {sigma} is the directed light scattering coefficient, and {beta} is the aerosol absorption coefficient. The coefficient {sigma}({lambda}) is measured by means of a nephelometer. Seemingly, if measure the values {alpha}({lambda}) and {sigma}({lambda}), it is easy to determine the value {beta}({lambda}). However, in practice it is almost impossible for a number of reasons. Firstly, the real values {alpha}({lambda}) and {sigma}({lambda}) are very close to each other, and the estimate of the parameter {beta}({lambda}) is concealed by the errors of measurements. Secondly, the aerosol optical characteristics on the long path and in the local volume of nephelometer can be different, that also leads to the errors in estimating {beta}({lambda}). Besides, there are serious difficulties in performing spectral measurements of {sigma}({lambda}) in infrared wavelength range. Taking into account these circumstances, in this paper we consider the statistical technique, which makes it possible to estimate the absorption coefficient of real aerosol on the basis of analysis
Averaging Internal Consistency Reliability Coefficients
ERIC Educational Resources Information Center
Feldt, Leonard S.; Charter, Richard A.
2006-01-01
Seven approaches to averaging reliability coefficients are presented. Each approach starts with a unique definition of the concept of "average," and no approach is more correct than the others. Six of the approaches are applicable to internal consistency coefficients. The seventh approach is specific to alternate-forms coefficients. Although the…
Cinson, Anthony D.; Crawford, Susan L.; MacFarlan, Paul J.; Hanson, Brady D.; Mathews, Royce
2012-09-24
Non-destructive and destructive testing methods were employed to evaluate a documented boric acid leakage path through an Alloy 600 control rod drive mechanism (CRDM) penetration from the North Anna Unit 2 reactor pressure vessel head that was removed from service in 2002. A previous ultrasonic in-service-inspection (ISI) conducted by industry prior to the head removal, identified a probable leakage path in Nozzle 63 located in the interference fit between the penetration tube and the vessel head. In this current examination, Nozzle 63 was examined using phased array (PA) ultrasonic testing with a 5.0-MHz, eight-element annular array; immersion data were acquired from the nozzle inner diameter (ID) surface. A variety of focal laws were employed to evaluate the signal responses from the interference fit region. These responses were compared to responses obtained from a mockup specimen that was used to determine detection limits and characterization capabilities for wastage and boric acid presence in the interference fit region. Nozzle 63 was destructively examined after the completion of the ultrasonic nondestructive evaluation (NDE) to visually assess the leak paths. These destructive and nondestructive results compared favorably
NASA Astrophysics Data System (ADS)
Chen, Mingjun; Xiao, Yong; Tian, Wenlan; Wu, Chunya; Chu, Xin
2014-05-01
Structure design and fabricating methods of three-dimensional (3D) artificial spherical compound eyes have been researched by many scholars. Micro-nano optical manufacturing is mostly used to process 3D artificial compound eyes. However, spherical optical compound eyes are less at optical performance than the eyes of insects, and it is difficult to further improve the imaging quality of compound eyes by means of micro-nano optical manufacturing. In this research, nonhomogeneous aspheric compound eyes (ACEs) are designed and fabricated. The nonhomogeneous aspheric structure is applied to calibrate the spherical aberration. Micro milling with advantages in processing three-dimensional micro structures is adopted to manufacture ACEs. In order to obtain ACEs with high imaging quality, the tool paths are optimized by analyzing the influence factors consisting of interpolation allowable error, scallop height and tool path pattern. In the experiments, two kinds of ACEs are manufactured by micro-milling with different too path patterns and cutting parameter on the miniature precision five-axis milling machine tool. The experimental results indicate that the ACEs of high surface quality can be achieved by circularly milling small micro-lens individually with changeable cutting depth. A prototype of the aspheric compound eye (ACE) with surface roughness ( R a) below 0.12 μm is obtained with good imaging performance. This research ameliorates the imaging quality of 3D artificial compound eyes, and the proposed method of micro-milling can improve surface processing quality of compound eyes.
Technology Transfer Automated Retrieval System (TEKTRAN)
Knowledge of the diffusion coefficient is necessary for modeling gas transport in soils and other porous media. This study was conducted to determine the relationship between the diffusion coefficient and pore structure parameters, such as the fractal dimension of pores (Dmp), the shortest path leng...
Midgley, Stewart; Schleich, Nanette
2015-05-01
A novel method for dual-energy X-ray analysis (DEXA) is tested using measurements of the X-ray linear attenuation coefficient μ. The key is a mathematical model that describes elemental cross sections using a polynomial in atomic number. The model is combined with the mixture rule to describe μ for materials, using the same polynomial coefficients. Materials are characterized by their electron density Ne and statistical moments Rk describing their distribution of elements, analogous to the concept of effective atomic number. In an experiment with materials of known density and composition, measurements of μ are written as a system of linear simultaneous equations, which is solved for the polynomial coefficients. DEXA itself involves computed tomography (CT) scans at two energies to provide a system of non-linear simultaneous equations that are solved for Ne and the fourth statistical moment R4. Results are presented for phantoms containing dilute salt solutions and for a biological specimen. The experiment identifies 1% systematic errors in the CT measurements, arising from third-harmonic radiation, and 20-30% noise, which is reduced to 3-5% by pre-processing with the median filter and careful choice of reconstruction parameters. DEXA accuracy is quantified for the phantom as the mean absolute differences for Ne and R4: 0.8% and 1.0% for soft tissue and 1.2% and 0.8% for bone-like samples, respectively. The DEXA results for the biological specimen are combined with model coefficients obtained from the tabulations to predict μ and the mass energy absorption coefficient at energies of 10 keV to 20 MeV. PMID:25931101
Kramer, Christian; Mochalski, Paweł; Unterkofler, Karl; Agapiou, Agapios; Ruzsanyi, Veronika; Liedl, Klaus R
2016-01-01
In this article, a database of blood:air and fat:air partition coefficients (λb:a and λf:a) is reported for estimating 1678 volatile organic compounds recently reported to appear in the volatilome of the healthy human. For this purpose, a quantitative structure-property relationship (QSPR) approach was applied and a novel method for Henry’s law constants prediction developed. A random forest model based on Molecular Operating Environment 2D (MOE2D) descriptors based on 2619 literature-reported Henry’s constant values was built. The calculated Henry’s law constants correlate very well (R2test = 0.967) with the available experimental data. Blood:air and fat:air partition coefficients were calculated according to the method proposed by Poulin and Krishnan using the estimated Henry’s constant values. The obtained values correlate reasonably well with the experimentally determined ones for a test set of 90 VOCs (R2 = 0.95). The provided data aim to fill in the literature data gap and further assist the interpretation of results in studies of the human volatilome. PMID:26815030
Kramer, Christian; Mochalski, Paweł; Unterkofler, Karl; Agapiou, Agapios; Ruzsanyi, Veronika; Liedl, Klaus R
2016-03-01
In this article, a database of blood:air and fat:air partition coefficients (λ b:a and λ f:a) is reported for estimating 1678 volatile organic compounds recently reported to appear in the volatilome of the healthy human. For this purpose, a quantitative structure-property relationship (QSPR) approach was applied and a novel method for Henry's law constants prediction developed. A random forest model based on Molecular Operating Environment 2D (MOE2D) descriptors based on 2619 literature-reported Henry's constant values was built. The calculated Henry's law constants correlate very well (R(2) test = 0.967) with the available experimental data. Blood:air and fat:air partition coefficients were calculated according to the method proposed by Poulin and Krishnan using the estimated Henry's constant values. The obtained values correlate reasonably well with the experimentally determined ones for a test set of 90 VOCs (R(2) = 0.95). The provided data aim to fill in the literature data gap and further assist the interpretation of results in studies of the human volatilome. PMID:26815030
The Use of Structure Coefficients in Regression Research.
ERIC Educational Resources Information Center
Perry, Lucille N.
It is recognized that parametric methods (e.g., t-tests, discriminant analysis, and methods based on analysis of variance) are special cases of canonical correlation analysis. In canonical correlation it has been argued that structure coefficients must be computed to correctly interpret results. It follows that structure coefficients may be useful…
NASA Technical Reports Server (NTRS)
Robinson, Judith L.; Charles, John B.; Rummel, John A. (Technical Monitor)
2000-01-01
Approximately three years ago, the Agency's lead center for the human elements of spaceflight (the Johnson Space Center), along with the National Biomedical Research Institute (NSBRI) (which has the lead role in developing countermeasures) initiated an activity to identify the most critical risks confronting extended human spaceflight. Two salient factors influenced this activity: first, what information is needed to enable a "go/no go" decision to embark on extended human spaceflight missions; and second, what knowledge and capabilities are needed to address known and potential health, safety and performance risks associated with such missions. A unique approach was used to first define and assess those risks, and then to prioritize them. This activity was called the Critical Path Roadmap (CPR) and it represents an opportunity to develop and implement a focused and evolving program of research and technology designed from a "risk reduction" perspective to prevent or minimize the risks to humans exposed to the space environment. The Critical Path Roadmap provides the foundation needed to ensure that human spaceflight, now and in the future, is as safe, productive and healthy as possible (within the constraints imposed on any particular mission) regardless of mission duration or destination. As a tool, the Critical Path Roadmap enables the decisionmaker to select from among the demonstrated or potential risks those that are to be mitigated, and the completeness of that mitigation. The primary audience for the CPR Web Site is the members of the scientific community who are interested in the research and technology efforts required for ensuring safe and productive human spaceflight. They may already be informed about the various space life sciences research programs or they may be newcomers. Providing the CPR content to potential investigators increases the probability of their delivering effective risk mitigations. Others who will use the CPR Web Site and its content
NASA Technical Reports Server (NTRS)
Robinson, Judith L.; Charles, John B.; Rummel, John A. (Technical Monitor)
2000-01-01
Approximately three years ago, the Agency's lead center for the human elements of spaceflight (the Johnson Space Center), along with the National Biomedical Research Institute (NSBRI) (which has the lead role in developing countermeasures) initiated an activity to identify the most critical risks confronting extended human spaceflight. Two salient factors influenced this activity: first, what information is needed to enable a "go/no go" decision to embark on extended human spaceflight missions; and second, what knowledge and capabilities are needed to address known and potential health, safety and performance risks associated with such missions. A unique approach was used to first define and assess those risks, and then to prioritize them. This activity was called the Critical Path Roadmap (CPR) and it represents an opportunity to develop and implement a focused and evolving program of research and technology designed from a "risk reduction" perspective to prevent or minimize the risks to humans exposed to the space environment. The Critical Path Roadmap provides the foundation needed to ensure that human spaceflight, now and in the future, is as safe, productive and healthy as possible (within the constraints imposed on any particular mission) regardless of mission duration or destination. As a tool, the Critical Path Roadmap enables the decision maker to select from among the demonstrated or potential risks those that are to be mitigated, and the completeness of that mitigation. The primary audience for the CPR Web Site is the members of the scientific community who are interested in the research and technology efforts required for ensuring safe and productive human spaceflight. They may already be informed about the various space life sciences research programs or they may be newcomers. Providing the CPR content to potential investigators increases the probability of their delivering effective risk mitigations. Others who will use the CPR Web Site and its
Thermoalgebras and path integral
NASA Astrophysics Data System (ADS)
Khanna, F. C.; Malbouisson, A. P. C.; Malbouisson, J. M. C.; Santana, A. E.
2009-09-01
Using a representation for Lie groups closely associated with thermal problems, we derive the algebraic rules of the real-time formalism for thermal quantum field theories, the so-called thermo-field dynamics (TFD), including the tilde conjugation rules for interacting fields. These thermo-group representations provide a unified view of different approaches for finite-temperature quantum fields in terms of a symmetry group. On these grounds, a path integral formalism is constructed, using Bogoliubov transformations, for bosons, fermions and non-abelian gauge fields. The generalization of the results for quantum fields in (S1)d×R topology is addressed.
Path Integrals and Supersolids
NASA Astrophysics Data System (ADS)
Ceperley, D. M.
2008-11-01
Recent experiments by Kim and Chan on solid 4He have been interpreted as discovery of a supersolid phase of matter. Arguments based on wavefunctions have shown that such a phase exists, but do not necessarily apply to solid 4He. Imaginary time path integrals, implemented using Monte Carlo methods, provide a definitive answer; a clean system of solid 4He should be a normal quantum solid, not one with superfluid properties. The Kim-Chan phenomena must be due to defects introduced when the solid is formed.
NASA Technical Reports Server (NTRS)
Mehhtz, Peter
2005-01-01
JPF is an explicit state software model checker for Java bytecode. Today, JPF is a swiss army knife for all sort of runtime based verification purposes. This basically means JPF is a Java virtual machine that executes your program not just once (like a normal VM), but theoretically in all possible ways, checking for property violations like deadlocks or unhandled exceptions along all potential execution paths. If it finds an error, JPF reports the whole execution that leads to it. Unlike a normal debugger, JPF keeps track of every step how it got to the defect.
Bleakley, Hoyt; Lin, Jeffrey
2012-01-01
We examine portage sites in the U.S. South, Mid-Atlantic, and Midwest, including those on the fall line, a geomorphological feature in the southeastern U.S. marking the final rapids on rivers before the ocean. Historically, waterborne transport of goods required portage around the falls at these points, while some falls provided water power during early industrialization. These factors attracted commerce and manufacturing. Although these original advantages have long since been made obsolete, we document the continuing importance of these portage sites over time. We interpret these results as path dependence and contrast explanations based on sunk costs interacting with decreasing versus increasing returns to scale. PMID:23935217
Bleakley, Hoyt; Lin, Jeffrey
2012-05-01
We examine portage sites in the U.S. South, Mid-Atlantic, and Midwest, including those on the fall line, a geomorphological feature in the southeastern U.S. marking the final rapids on rivers before the ocean. Historically, waterborne transport of goods required portage around the falls at these points, while some falls provided water power during early industrialization. These factors attracted commerce and manufacturing. Although these original advantages have long since been made obsolete, we document the continuing importance of these portage sites over time. We interpret these results as path dependence and contrast explanations based on sunk costs interacting with decreasing versus increasing returns to scale. PMID:23935217
Drag Coefficient of Hexadecane Particles
NASA Astrophysics Data System (ADS)
Nakao, Yoshinobu; Hishida, Makoto; Kajimoto, Sadaaki; Tanaka, Gaku
This paper deals with the drag coefficient of solidified hexadecane particles and their free rising velocity in liquid. The drag coefficient was experimentally investigated in Reynolds number range of about 40-300. The present experimental results are summarized in the following; (1) the drag coefficient of solidified hexadecane particles formed in liquid coolant by direct contact cooling is higher than that of a smooth surface sphere, this high drag coefficient seems to be attributed to the non-smooth surface of the solidified hexadecane particles, (2) experimental correlation for the drag coefficient of the solidified hexadecane particles was proposed, (3 ) the measured rising velocity of the solidified hexadecane particle agrees well with the calculated one, (4) the drag coefficients of hexadecane particles that were made by pouring hexadecane liquid into a solid hollow sphere agreed well with the drag coefficient of smooth surface sphere.
An Introduction to Career Path Employability Profiles.
ERIC Educational Resources Information Center
Alvir, Howard P.
An employability profile specifies employment opportunities for which an individual is qualified. A career path is the term applied to an employability profile that combines both the career ladder aspect of advancement and the career lattice element of wide selection. After a descriptive analysis of typical employability profiles, this document…
Internet's critical path horizon
NASA Astrophysics Data System (ADS)
Valverde, S.; Solé, R. V.
2004-03-01
Internet is known to display a highly heterogeneous structure and complex fluctuations in its traffic dynamics. Congestion seems to be an inevitable result of user's behavior coupled to the network dynamics and it effects should be minimized by choosing appropriate routing strategies. But what are the requirements of routing depth in order to optimize the traffic flow? In this paper we analyse the behavior of Internet traffic with a topologically realistic spatial structure as described in a previous study [S.-H. Yook et al., Proc. Natl Acad. Sci. USA 99, 13382 (2002)]. The model involves self-regulation of packet generation and different levels of routing depth. It is shown that it reproduces the relevant key, statistical features of Internet's traffic. Moreover, we also report the existence of a critical path horizon defining a transition from low-efficient traffic to highly efficient flow. This transition is actually a direct consequence of the web's small world architecture exploited by the routing algorithm. Once routing tables reach the network diameter, the traffic experiences a sudden transition from a low-efficient to a highly-efficient behavior. It is conjectured that routing policies might have spontaneously reached such a compromise in a distributed manner. Internet would thus be operating close to such critical path horizon.
Gas Path Sealing in Turbine Engines
NASA Technical Reports Server (NTRS)
Ludwig, L. P.
1978-01-01
A survey of gas path seals is presented with particular attention given to sealing clearance effects on engine component efficiency. The effects on compressor pressure ratio and stall margin are pointed out. Various case-rotor relative displacements, which affect gas path seal clearances, are identified. Forces produced by nonuniform sealing clearances and their effect on rotor stability are discussed qualitatively, and recent work on turbine-blade-tip sealing for high temperature is described. The need for active clearance control and for engine structural analysis is discussed. The functions of the internal-flow system and its seals are reviewed.
NASA Astrophysics Data System (ADS)
Lewandowska, Monika; Herzog, Robert
2011-10-01
Two ITER TF dual channel Cable-in-Conduit Conductors (CICCs) have been tested in the SULTAN test facility. The samples were heated either by foil heaters mounted on the outside of the conductor jacket or by induced AC losses. The steady-state temperature response of several thermometers installed on the jacket surface as well as inside the cable were analyzed using the two-channel analytical model proposed by Renard et al. to obtain the equivalent transverse heat transfer coefficient between the bundle and central channel as a function of the mass flow rate. In addition, on the basis of the measured pressure drop and helium flow velocities, the friction factors for helium flow in the bundle and in the central channel were determined. The obtained results may serve as a reference for these cables.
Optimum flight paths of turbojet aircraft
NASA Technical Reports Server (NTRS)
Miele, Angelo
1955-01-01
The climb of turbojet aircraft is analyzed and discussed including the accelerations. Three particular flight performances are examined: minimum time of climb, climb with minimum fuel consumption, and steepest climb. The theoretical results obtained from a previous study are put in a form that is suitable for application on the following simplifying assumptions: the Mach number is considered an independent variable instead of the velocity; the variations of the airplane mass due to fuel consumption are disregarded; the airplane polar is assumed to be parabolic; the path curvatures and the squares of the path angles are disregarded in the projection of the equation of motion on the normal to the path; lastly, an ideal turbojet with performance independent of the velocity is involved. The optimum Mach number for each flight condition is obtained from the solution of a sixth order equation in which the coefficients are functions of two fundamental parameters: the ratio of minimum drag in level flight to the thrust and the Mach number which represents the flight at constant altitude and maximum lift-drag ratio.
Definition of average path and relativity parameter computation in CASA
NASA Astrophysics Data System (ADS)
Wu, Dawei; Huang, Yan; Chen, Xiaohua; Yu, Chang
2001-09-01
System CASA (computer-assisted semen analysis) is a medical applicable system which gets the sperm motility and its parameters using image processing method. But there is no any authoritative administration or academic organization gives a set of criterion for CASA now result in lowering the effective compare of work between the labs or researchers. The average path and parameters relative to it as average path velocity, amplitude of lateral head displacement and beat cross frequency are often unable to compare between systems because of different algorithm. The paper presents a new algorithm that could define the average path uniquely and compute those 3 parameters above quickly and handy from any real path.
Distributional properties of stochastic shortest paths for smuggled nuclear material
Cuellar, Leticia; Pan, Feng; Roach, Fred; Saeger, Kevin J
2011-01-05
The shortest path problem on a network with fixed weights is a well studied problem with applications to many diverse areas such as transportation and telecommunications. We are particularly interested in the scenario where a nuclear material smuggler tries to succesfully reach herlhis target by identifying the most likely path to the target. The identification of the path relies on reliabilities (weights) associated with each link and node in a multi-modal transportation network. In order to account for the adversary's uncertainty and to perform sensitivity analysis we introduce random reliabilities. We perform some controlled experiments on the grid and present the distributional properties of the resulting stochastic shortest paths.
Which coordinate system for modelling path integration?
Vickerstaff, Robert J; Cheung, Allen
2010-03-21
Path integration is a navigation strategy widely observed in nature where an animal maintains a running estimate, called the home vector, of its location during an excursion. Evidence suggests it is both ancient and ubiquitous in nature, and has been studied for over a century. In that time, canonical and neural network models have flourished, based on a wide range of assumptions, justifications and supporting data. Despite the importance of the phenomenon, consensus and unifying principles appear lacking. A fundamental issue is the neural representation of space needed for biological path integration. This paper presents a scheme to classify path integration systems on the basis of the way the home vector records and updates the spatial relationship between the animal and its home location. Four extended classes of coordinate systems are used to unify and review both canonical and neural network models of path integration, from the arthropod and mammalian literature. This scheme demonstrates analytical equivalence between models which may otherwise appear unrelated, and distinguishes between models which may superficially appear similar. A thorough analysis is carried out of the equational forms of important facets of path integration including updating, steering, searching and systematic errors, using each of the four coordinate systems. The type of available directional cue, namely allothetic or idiothetic, is also considered. It is shown that on balance, the class of home vectors which includes the geocentric Cartesian coordinate system, appears to be the most robust for biological systems. A key conclusion is that deducing computational structure from behavioural data alone will be difficult or impossible, at least in the absence of an analysis of random errors. Consequently it is likely that further theoretical insights into path integration will require an in-depth study of the effect of noise on the four classes of home vectors. PMID:19962387
Microcomputer Listens to the Coefficient of Restitution.
ERIC Educational Resources Information Center
Smith, P. A.; And Others
1981-01-01
Describes a procedure for determining the coefficient of restitution using a microcomputer which collects and sends data to a large computer where analysis is done and graphical output is generated. The data collection hardware and software are described, and results are illustrated. (Author/SK)
Uses and Misuses of the Correlation Coefficient.
ERIC Educational Resources Information Center
Onwuegbuzie, Anthony J.; Daniel, Larry G.
The purpose of this paper is to provide an in-depth critical analysis of the use and misuse of correlation coefficients. Various analytical and interpretational misconceptions are reviewed, beginning with the egregious assumption that correlational statistics may be useful in inferring causality. Additional misconceptions, stemming from…
Quadrature formulas for Fourier coefficients
NASA Astrophysics Data System (ADS)
Bojanov, Borislav; Petrova, Guergana
2009-09-01
We consider quadrature formulas of high degree of precision for the computation of the Fourier coefficients in expansions of functions with respect to a system of orthogonal polynomials. In particular, we show the uniqueness of a multiple node formula for the Fourier-Tchebycheff coefficients given by Micchelli and Sharma and construct new Gaussian formulas for the Fourier coefficients of a function, based on the values of the function and its derivatives.
NASA Astrophysics Data System (ADS)
Xu, Li-Hong; Lees, Ronald M.; Hougen, Jon T.
2012-06-01
Stemming from the observation of inverted A/E splittings for the ν2 and ν9 asymmetric CH-stretching modes in methanol, there has been much theoretical interest in attempting to explain the nature of the inversion. We have recently examined the ab initio normal-mode vibrational displacement vectors along the internal rotation path for the three C-H stretching vibrations in methanol, both in the symmetrized and non-symmetrized PAM coordinates. Graphical representations of the Cartesian atomic normal mode displacement vectors di(γ) determined by the Gaussian suite of programs for the three CH stretching motions, ν2(A1), ν3(A1) and ν9(A2), along the steepest-descent internal rotation path γ in methanol (CH_3OH) will be presented and discussed, where A1 and A2 are notations in permutation-inversion group G6. These modes are interesting because the symmetry environment of each C-H bond changes significantly during the internal rotation, i.e., each of the methyl bonds takes turns passing (twice for a complete torsional revolution) through the plane of symmetry of the COH frame of the molecule. We present some simple theoretical models which can be used to help understand these displacement vectors. Although this is work in progress, some explanation is already possible for the rather irregular (avoided-crossing-like) behavior of these displacement vectors.
NASA Astrophysics Data System (ADS)
Shmakov, A. V.; Gorbunov, M. E.
2016-07-01
Based on more than 4500 sessions of radio transillumination of Earth's atmosphere along the satellite-atmosphere-satellite path obtained in the COSMIC experiment, the distribution along latitude and over local time of the spatial spectra of variations in the ionospheric phase delay and signal amplitude has been analyzed. The spatial spectra have been calculated for two height ranges, i.e., 60-80 and 80-100 km. In the phase signal spectrum within the height range 80-100 km, the second maximum in the vicinity of a frequency of 7-8 rad/km is clearly seen. Its diurnal and latitudinal behavior and its decrease towards high latitudes in both hemispheres can also be seen. In the height range of 60-80 km, this maximum is hardly observed. Although solar flares can lead to substantial local changes in the electron concentration, no substantial difference in the behavior of the spectral densities of the amplitude and phase delay at long limb paths was observed within these two height ranges on days of active and quiet sun. The latter fact makes it possible to develop a united algorithm of optimal ionospheric correction of the radio occultation data independent of solar activity.
Quantitative Molecular Thermochemistry Based on Path Integrals
Glaesemann, K R; Fried, L E
2005-03-14
The calculation of thermochemical data requires accurate molecular energies and heat capacities. Traditional methods rely upon the standard harmonic normal mode analysis to calculate the vibrational and rotational contributions. We utilize path integral Monte Carlo (PIMC) for going beyond the harmonic analysis, to calculate the vibrational and rotational contributions to ab initio energies. This is an application and extension of a method previously developed in our group.
Water flow paths in a forested catchment of the East Asian monsoon region
NASA Astrophysics Data System (ADS)
Payeur-Poirier, Jean-Lionel; Hopp, Luisa; Peiffer, Stefan
2015-04-01
The climate of South Korea is strongly influenced by the East Asian summer monsoon. It is hypothesized that the high precipitation regime of the summer monsoon causes significant changes in the hydrological behaviour of forested catchments, namely in water quantity, quality and flow paths. We conducted high frequency hydrometric, isotopic, hydrochemical and meteorological measurements in a forested catchment before, during and after the 2013 summer monsoon season. The catchment is located within the Lake Soyang watershed, where recent trends of increasing eutrophication, sediment load and organic carbon load have been observed. We studied the temporal variability of catchment runoff and the spatial and temporal variability of water flow paths in relation with the hydrological conditions of the hillslope, toeslope and riparian elements of the catchment. For the summer monsoon season, the runoff coefficient approximated 68%. During this period, for the 16 monitored individual storm events ranging between 13 mm and 126 mm in precipitation, the runoff coefficient greatly varied and a threshold relationship with soil moisture was observed. Analyses of hysteresis loops of catchment runoff also revealed threshold relationships with precipitation and soil moisture, as water flow paths were activated or not in different parts of the catchment. The variation of the electrical conductivity of catchment runoff through the summer monsoon also revealed the occurrence of threshold relationships. A principal component analysis (PCA) and an end-member mixing analysis (EMMA) were performed in order to quantify the contribution of the different landscape elements to catchment runoff. The combination of the hydrometric, isotopic and hydrochemical approaches allowed us to test our hypothesis and to shed light on the threshold relationships observed at the catchment. The findings of this study could be useful for the estimation of the water balance of the Lake Soyang watershed as well
Coefficient Alpha: A Reliability Coefficient for the 21st Century?
ERIC Educational Resources Information Center
Yang, Yanyun; Green, Samuel B.
2011-01-01
Coefficient alpha is almost universally applied to assess reliability of scales in psychology. We argue that researchers should consider alternatives to coefficient alpha. Our preference is for structural equation modeling (SEM) estimates of reliability because they are informative and allow for an empirical evaluation of the assumptions…
Minimal entropy probability paths between genome families.
Ahlbrandt, Calvin; Benson, Gary; Casey, William
2004-05-01
We develop a metric for probability distributions with applications to biological sequence analysis. Our distance metric is obtained by minimizing a functional defined on the class of paths over probability measures on N categories. The underlying mathematical theory is connected to a constrained problem in the calculus of variations. The solution presented is a numerical solution, which approximates the true solution in a set of cases called rich paths where none of the components of the path is zero. The functional to be minimized is motivated by entropy considerations, reflecting the idea that nature might efficiently carry out mutations of genome sequences in such a way that the increase in entropy involved in transformation is as small as possible. We characterize sequences by frequency profiles or probability vectors, in the case of DNA where N is 4 and the components of the probability vector are the frequency of occurrence of each of the bases A, C, G and T. Given two probability vectors a and b, we define a distance function based as the infimum of path integrals of the entropy function H( p) over all admissible paths p(t), 0 < or = t< or =1, with p(t) a probability vector such that p(0)=a and p(1)=b. If the probability paths p(t) are parameterized as y(s) in terms of arc length s and the optimal path is smooth with arc length L, then smooth and "rich" optimal probability paths may be numerically estimated by a hybrid method of iterating Newton's method on solutions of a two point boundary value problem, with unknown distance L between the abscissas, for the Euler-Lagrange equations resulting from a multiplier rule for the constrained optimization problem together with linear regression to improve the arc length estimate L. Matlab code for these numerical methods is provided which works only for "rich" optimal probability vectors. These methods motivate a definition of an elementary distance function which is easier and faster to calculate, works on non
NASA Astrophysics Data System (ADS)
Dudaryonok, A. S.; Lavrentieva, N. N.; Buldyreva, J.; Margulès, L.; Motiyenko, R. A.; Rohart, F.
2014-09-01
Rotational transitions in CH335Cl mixed with CO2 are recorded at 296 K and total pressures up to 0.6 Torr in the frequency interval 186-901 GHz (1.6-0.3 mm) for J=6→7, 10→11, 17→18, 22→23, 31→32, 33→34 and K=0-6, using the frequency-modulation spectrometer of the Laboratory PhLAM (Lille, France). These line-shapes are analyzed with the commonly used Voigt profile as well as with more refined Speed-Dependent Voigt and Galatry models accounting for the line narrowing induced, respectively, by the speed-dependence of the relaxation parameters and by velocity-changing collisions. Due to the high line intensities, the fitting procedure involves the full implementation of the Bee-Lambert law instead of its traditional linear approximation. The experimentally deduced J- and K-dependences of the pressure-broadening coefficients are further used to obtain the model parameters of a semi-empirical approach allowing massive calculations of line-shape parameters for enlarged ranges of rotational quantum numbers requested by spectroscopic databases.
NASA Astrophysics Data System (ADS)
Deng, Yun-Kun; Xiao, Deng-Ming
2013-03-01
The electron swarm parameters including the density-normalized effective ionization coefficients (α-η)/N and the electron drift velocities Ve are calculated for a gas mixture of CF3I with N2 and CO2 by solving the Boltzmann equation in the condition of a steady-state Townsend (SST) experiment. The overall density-reduced electric field strength is from 100 Td to 1000 Td (1 Td = 10-17 V·cm2), while the CF3I content k in the gas mixture can be varied over the range from 0% to 100%. From the variation of (α-η)/N with the CF3I mixture ratio k, the limiting field strength (E/N)lim for each CF3I concentration is derived. It is found that for the mixtures with 70% CF3I, the values of (E/N)lim are essentially the same as that for pure SF6. Additionally, the global warming potential (GWP) and the liquefaction temperature of the gas mixtures are also taken into account to evaluate the possibility of application in the gas insulation of power equipment.
NASA Astrophysics Data System (ADS)
Zamani, Reza; Mirabbasi, Rasoul; Abdollahi, Sajjad; Jhajharia, Deepak
2016-03-01
Due to the substantial decrease of water resources as well as the increase in demand and climate change phenomenon, analyzing the trend of hydrological parameters is of paramount importance. In the present study, investigations were carried out to identify the trends in streamflow at 20 hydrometric stations and 11 rainfall gauging stations located in Karkheh River Basin (KRB), Iran, in monthly, seasonal, and annual time scales during the last 38 years from 1974 to 2011. This study has been conducted using two versions of Mann-Kendall tests, including (i) Mann-Kendall test by considering all the significant autocorrelation structure (MK3) and (ii) Mann-Kendall test by considering LTP and Hurst coefficient (MK4). The results indicate that the KRB streamflow trend (using both test versions) has decreased in all three time scales. There is a significant decreasing trend in 78 and 73 % of the monthly cases using the MK3 and MK4 tests, respectively, while these percentages changed to 80 and 70 % on seasonal and annual time scales, respectively. Investigation of the trend line slope using Theil-Sen's estimator showed a negative trend in all three time scales. The use of MK4 test instead of the MK3 test has caused a decrease in the significance level of Mann-Kendall Z-statistic values. The results of the precipitation trends indicate both increasing and decreasing trends. Also, the correlation between the area average streamflow and precipitation shows a strong correlation in annual time scale in the KRB.
NASA Astrophysics Data System (ADS)
Mohammadi, E.; Hunter, A.
2012-07-01
Path finding solutions are becoming a major part of many GIS applications including location based services and web-based GIS services. Most traditional path finding solutions are based on shortest path algorithms that tend to minimize the cost of travel from one point to another. These algorithms make use of some cost criteria that is usually an attribute of the edges in the graph network. Providing one shortest path limits user's flexibility when choosing a possible route, especially when more than one parameter is utilized to calculate cost (e.g., when length, number of traffic lights, and number of turns are used to calculate network cost.) K shortest path solutions tend to overcome this problem by providing second, third, and Kth shortest paths. These algorithms are efficient as long as the graphs edge weight does not change dynamically and no other parameters affect edge weights. In this paper we try to go beyond finding shortest paths based on some cost value, and provide all possible paths disregarding any parameter that may affect total cost. After finding all possible paths, we can rank the results by any parameter or combination of parameters, without a substantial increase in time complexity.
Slip and accommodation coefficients from rarefaction and roughness in rotating microscale disk flows
NASA Astrophysics Data System (ADS)
Blanchard, Danny; Ligrani, Phil
2007-06-01
Accommodation coefficients are determined from experimental results and analysis based on the Navier-Stokes equations for rotation-induced flows in C-shaped fluid chamber passages formed between a rotating disk and a stationary surface. A first-order boundary condition is used to model the slip flow. The fluid chamber passage height ranges from 6.85to29.2μm to give Knudsen numbers from 0.0025 to 0.031 for air and helium. In all cases, roughness size is large compared to molecular mean free path. The unique method presented for deducing tangential momentum accommodation coefficients gives values with less uncertainty compared to procedures that rely on flows in stationary tubes and channels. When channel height is defined at the tops of the roughness elements, slip velocity magnitudes and associated accommodation coefficients are a result of rarefaction at solid-gas interfaces and shear at the gas-gas interfaces. With this arrangement, tangential accommodation coefficients obtained with this approach decrease, and slip velocity magnitudes increase, at a particular value of Knudsen number, as the level of surface roughness increases. At values of the mean roughness height greater than 500nm, accommodation coefficients then appear to be lower in air flows than in helium flows, when compared for a particular roughness configuration. When channel height is defined midway between the crests and troughs of the roughness elements, nondimensional pressure rise data show little or no dependence on the level of disk surface roughness and working fluid. With this arrangement, slip is largely independent of surface roughness magnitude and mostly due to rarefaction, provided the appropriate channel height is chosen to define the roughness height.
RADIONUCLIDE RISK COEFFICIENT UNCERTAINTY REPORT
EPA has published excess cancer risk coefficients for the US population in Federal Guidance Report 13 (FGR 13). FGR 13 gives separate risk coefficients for food ingestion, water ingestion, inhalation, and external exposure for each of over 800 radionuclides. Some information on...
Air- and N2-Broadening Coefficients and Pressure-Shift Coefficients in the C-12(O2-16) Laser Bands
NASA Technical Reports Server (NTRS)
Devi, V. Malathy; Benner, D. Chris; Smith, Mary Ann H.; Rinsland, Curtis P.
1998-01-01
In this paper we report the pressure broadening and the pressure-induced line shift coefficients for 46 individual rovibrational lines in both the (12)C(16)O2, 00(sup 0)1-(10(sup 0)0-02(sup 0)0)I, and 00(sup 0)1-(10(sup 0)0-02(sup 0)0)II, laser bands (laser band I centered at 960.959/cm and laser band II centered at 1063.735/cm) determined from spectra recorded with the McMath-Pierce Fourier transform spectrometer. The results were obtained from analysis of 10 long-path laboratory absorption spectra recorded at room temperature using a multispectrum nonlinear least-squares technique. Pressure effects caused by both air and nitrogen have been investigated. The air-broadening coefficients determined in this study agree well with the values in the 1996 HITRAN database; ratios and standard deviations of the ratios of the present air-broadening measurements to the 1996 HITRAN values for the two laser bands are: 1.005(15) for laser band I and 1.005(14) for laser band II. Broadening by nitrogen is 3 to 4% larger than that of air. The pressure-induced line shift coefficients are found to be transition dependent and different for the P- and R-branch lines with same J" value. No noticeable differences in the shift coefficients caused by air and nitrogen were found. The results obtained are compared with available values previously reported in the literature.
NASA Technical Reports Server (NTRS)
McClinton, C.; Rondakov, A.; Semenov, V.; Kopehenov, V.
1991-01-01
NASA has contracted with the Central Institute of Aviation Motors CIAM to perform a flight test and ground test and provide a scramjet engine for ground test in the United States. The objective of this contract is to obtain ground to flight correlation for a supersonic combustion ramjet (scramjet) engine operating point at a Mach number of 6.5. This paper presents results from a flow path performance and thermal evaluation performed on the design proposed by the CIAM. This study shows that the engine will perform in the scramjet mode for stoichiometric operation at a flight Mach number of 6.5. Thermal assessment of the structure indicates that the combustor cooling liner will provide adequate cooling for a Mach number of 6.5 test condition and that optional material proposed by CIAM for the cowl leading-edge design are required to allow operation with or without a type IV shock-shock interaction.
Wassenburg, Stephanie I.; de Koning, Björn B.; de Vries, Meinou H.; van der Schoot, Menno
2016-01-01
Using a component processes task (CPT) that differentiates between higher-level cognitive processes of reading comprehension provides important advantages over commonly used general reading comprehension assessments. The present study contributes to further development of the CPT by evaluating the relative contributions of its components (text memory, text inferencing, and knowledge integration) and working memory to general reading comprehension within a single study using path analyses. Participants were 173 third- and fourth-grade children. As hypothesized, knowledge integration was the only component of the CPT that directly contributed to reading comprehension, indicating that the text-inferencing component did not assess inferential processes related to reading comprehension. Working memory was a significant predictor of reading comprehension over and above the component processes. Future research should focus on finding ways to ensure that the text-inferencing component taps into processes important for reading comprehension. PMID:27378989
Wassenburg, Stephanie I; de Koning, Björn B; de Vries, Meinou H; van der Schoot, Menno
2016-01-01
Using a component processes task (CPT) that differentiates between higher-level cognitive processes of reading comprehension provides important advantages over commonly used general reading comprehension assessments. The present study contributes to further development of the CPT by evaluating the relative contributions of its components (text memory, text inferencing, and knowledge integration) and working memory to general reading comprehension within a single study using path analyses. Participants were 173 third- and fourth-grade children. As hypothesized, knowledge integration was the only component of the CPT that directly contributed to reading comprehension, indicating that the text-inferencing component did not assess inferential processes related to reading comprehension. Working memory was a significant predictor of reading comprehension over and above the component processes. Future research should focus on finding ways to ensure that the text-inferencing component taps into processes important for reading comprehension. PMID:27378989
PathCase-SB architecture and database design
2011-01-01
Background Integration of metabolic pathways resources and regulatory metabolic network models, and deploying new tools on the integrated platform can help perform more effective and more efficient systems biology research on understanding the regulation in metabolic networks. Therefore, the tasks of (a) integrating under a single database environment regulatory metabolic networks and existing models, and (b) building tools to help with modeling and analysis are desirable and intellectually challenging computational tasks. Description PathCase Systems Biology (PathCase-SB) is built and released. The PathCase-SB database provides data and API for multiple user interfaces and software tools. The current PathCase-SB system provides a database-enabled framework and web-based computational tools towards facilitating the development of kinetic models for biological systems. PathCase-SB aims to integrate data of selected biological data sources on the web (currently, BioModels database and KEGG), and to provide more powerful and/or new capabilities via the new web-based integrative framework. This paper describes architecture and database design issues encountered in PathCase-SB's design and implementation, and presents the current design of PathCase-SB's architecture and database. Conclusions PathCase-SB architecture and database provide a highly extensible and scalable environment with easy and fast (real-time) access to the data in the database. PathCase-SB itself is already being used by researchers across the world. PMID:22070889
UV laser long-path absorption spectroscopy
NASA Technical Reports Server (NTRS)
Dorn, Hans-Peter; Brauers, Theo; Neuroth, Rudolf
1994-01-01
Long path Differential Optical Absorption Spectroscopy (DOAS) using a picosecond UV laser as a light source was developed in our institute. Tropospheric OH radicals are measured by their rotational absorption lines around 308 nm. The spectra are obtained using a high resolution spectrograph. The detection system has been improved over the formerly used optomechanical scanning device by application of a photodiode array which increased the observed spectral range by a factor of 6 and which utilizes the light much more effectively leading to a considerable reduction of the measurement time. This technique provides direct measurements of OH because the signal is given by the product of the absorption coefficient and the OH concentration along the light path according to Lambert-Beers law. No calibration is needed. Since the integrated absorption coefficient is well known the accuracy of the measurement essentially depends on the extent to which the OH absorption pattern can be detected in the spectra. No interference by self generated OH radicals in the detection lightpath has been observed. The large bandwidth (greater than 0.15 nm) and the high spectral resolution (1.5 pm) allows absolute determination of interferences by other trace gas absorptions. The measurement error is directly accessible from the absorption-signal to baseline-noise ratio in the spectra. The applicability of the method strongly depends on visibility. Elevated concentrations of aerosols lead to considerable attenuation of the laser light which reduces the S/N-ratio. In the moderately polluted air of Julich, where we performed a number of OH measurement spectra. In addition absorption features of unidentified species were frequently detected. A quantitative deconvolution even of the known species is not easy to achieve and can leave residual structures in the spectra. Thus interferences usually increase the noise and deteriorate the OH detection sensitivity. Using diode arrays for sensitive