ERIC Educational Resources Information Center
Lai, Dejian; Huang, Jin; Risser, Jan M.; Kapadia, Asha S.
2008-01-01
In this article, we report statistical properties of two classes of generalized Gini coefficients (G1 and G2). The theoretical results were assessed via Monte Carlo simulations. Further, we used G1 and G2 on life expectancy to measure health inequalities among the provinces of China and the states of the United States. For China, the results…
Estimation of the Gini coefficient for the lognormal distribution of income using the Lorenz curve.
Darkwah, Kwasi A; Nortey, Ezekiel N N; Lotsi, Anani
2016-01-01
The main objective of the study is to compare the Newton-Cotes methods such as the Trapezium rule, Simpson 1/3 rule and Simpson 3/8 rule to estimate the area under the Lorenz curve and Gini coefficient of income using polynomial function with degree 5. Comparing the Gini coefficients of income computed from the Polynomial function with degree 5 for the Trapezium, Simpson 1/3 and Simpson 3/8 methods using the relative errors showed that the trapezium rule, Simpson's 1/3 rule and Simpson's 3/8 rule show negative biases with the Simpson 1/3 rule yielding the lowest absolute relative true error of 4.230711 %. PMID:27516934
Equality of Medical Health Resource Allocation in China Based on the Gini Coefficient Method
JIN, Jian; WANG, Jianxiang; MA, Xiaoyi; WANG, Yuding; LI, Renyong
2015-01-01
Background: The Chinese government is trying to achieve the goal of “universal access to basic health care services”. However, the inequality of the distribution of health care resources across the country is the biggest obstacle. This paper aims to explore these inequalities and the extent to which the method of analysis influences the perception. Methods: The indicators of health care resource distribution studied consisted of the number of health care institutions, the number of beds in health care institutions and the number of medical personnel. Data were obtained from the China Statistical Yearbook 2014. The extent of equality was assessed using the Lorenz Curve and Gini Coefficient Method. Results: Health care resource distribution in China demonstrates inequalities. The demographic Gini Coefficients based on the Lorenz Curves for the distribution of health care institutions, beds in health care institutions and medical personnel are 0.190, 0.070 and 0.070 respectively, while the corresponding Coefficients based on geographical areas are 0.616, 0.639 and 0.650. Conclusion: The equality of China’s demographically assessed distribution of health care resources is greater than that of its geographically measured distribution. Coefficients expressed by population imply there is ready access to healthcare in all regions, whilst the Coefficients by geographical area apparently indicate inequality. This is the result of the sparsity of population. PMID:26056663
Zhou, Shenbei; Du, Amin; Bai, Minghao
2015-01-01
The equitable allocation of water governance responsibilities is very important yet difficult to achieve, particularly for a basin which involves many stakeholders and policymakers. In this study, the environmental Gini coefficient model was applied to evaluate the inequality of water governance responsibility allocation, and an environmental Gini coefficient optimisation model was built to achieve an optimal adjustment. To illustrate the application of the environmental Gini coefficient, the heavily polluted transboundary Taihu Lake Basin in China, was chosen as a case study. The results show that the original environmental Gini coefficient of the chemical oxygen demand (COD) was greater than 0.2, indicating that the allocation of water governance responsibilities in Taihu Lake Basin was unequal. Of seven decision-making units, three were found to be inequality factors and were adjusted to reduce the water pollutant emissions and to increase the water governance inputs. After the adjustment, the environmental Gini coefficient of the COD was less than 0.2 and the reduction rate was 27.63%. The adjustment process provides clear guidance for policymakers to develop appropriate policies and improve the equality of water governance responsibility allocation. PMID:25860708
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
ERIC Educational Resources Information Center
Yingxiu, Yang
2006-01-01
Using statistical data on the implementing conditions of China's educational expenditure published by the state, this paper studies the Gini coefficient of the budget educational public expenditure per student in order to examine the concentration degree of the educational expenditure for China's basic education and analyze its balanced…
Measuring Education Inequality: Gini Coefficients of Education. Policy Research Working Paper.
ERIC Educational Resources Information Center
Thomas, Vinod; Wang, Yan; Fan, Xibo
This paper aims at developing a measure for educational inequality for a large number of countries over time, using the concept of education Gini index based on school attainment data of the concerned population (or labor force). Education Gini could be used as one of the indicators of welfare, complementing average educational attainment, health…
ERIC Educational Resources Information Center
Bennett, Daniel L.
2011-01-01
This paper estimates historical measures of equality in the distribution of education in the United States by age group and sex. Using educational attainment data for the population, the EduGini measure indicates that educational inequality in the U.S. declined significantly between 1950 and 2009. Reductions in educational inequality were more…
NASA Astrophysics Data System (ADS)
Florian, Michael K.; Gladders, Michael D.; Li, Nan; Sharon, Keren
2016-01-01
The sample of cosmological strong lensing systems has been steadily growing in recent years and with the advent of the next generation of space-based survey telescopes, the sample will reach into the thousands. The accuracy of strong lens models relies on robust identification of multiple image families of lensed galaxies. For the most massive lenses, often more than one background galaxy is magnified and multiply imaged, and even in the cases of only a single lensed source, identification of counter images is not always robust. Recently, we have shown that the Gini coefficient in space-telescope-quality imaging is a measurement of galaxy morphology that is relatively well-preserved by strong gravitational lensing. Here, we investigate its usefulness as a diagnostic for the purposes of image family identification and show that it can remove some of the degeneracies encountered when using color as the sole diagnostic, and can do so without the need for additional observations since whenever a color is available, two Gini coefficients are as well.
Asl, Iravan Masoudi; Abolhallaje, Masoud; Raadabadi, Mehdi; Nazari, Hamed; Nazari, Aslan; Salimi, Mohammad; Javani, Ali
2015-01-01
Introduction Fair distribution of hospital beds across various regions is a controversial subject. Resource allocation in health systems rarely has focused on those who need it most and, in addition, is often influenced by political interests. The study assesses the distribution of hospital beds in different regions in Tehran, Iran, during 2010–2012. Methods This cross-sectional study was conducted in all regions of Tehran (22 regions) during 2010 to 2012. All hospital beds in these regions are included in the study. Data regarding populations of each region were obtained from the Statistics Center of Iran. According to the data, the total number of beds (N.B) and population (P) in 2010 (N.B=19075, P= 7585000), 2011 (N.B=21632, P= 9860500), and 2012 (N.B=21808, P=12818650). The instrument was a form, including the name of the hospital, the district in which the hospital was located, the number of staffed beds, the name of each region, and its population. Data analysis was performed using DASP software version 2.3. Results The results demonstrate that the Gini coefficient of distributed beds in 22 regions of Tehran was 0.46 in all three years and specifically calculated 0.4666 in 2010, 0.4658 in 2011 and 0.4652 in 2012. The Gini coefficient of beds in 22 regions of Tehran is not fair in comparison with the population of each region during the years 2010 to 2012. Conclusion The results demonstrate that the distribution of beds in regions in Tehran is not fair in relation to the population of each region—and some regions had no hospitals. Therefore, it is essential for policymakers to frequently monitor this issue and investigate the fair distribution of hospital beds. PMID:26813480
Pascual, Cruz; Regidor, Enrique; Astasio, Paloma; Ortega, Paloma; Navarro, Pedro; Domínguez, Vicente
2007-08-01
This paper evaluates the association between socioeconomic environment in the province of residence and physical inactivity, using measures of current and sustained area-based adverse socioeconomic environment. The analysis included 19,324 individuals representative of the Spanish non-institutionalised population aged 16-74 years. The measure of association estimated was the prevalence odds ratio for physical inactivity by current gross domestic product per capita (GDPpc) and current Gini coefficient, and by number of times each province has had a low GDPpc and number of times each province has had a high Gini coefficient in the last two decades. After adjusting for age, individual socioeconomic characteristics, and number of sports facilities per 1,000 population, the odds ratio for physical inactivity in residents of provinces with the lowest current GDPpc versus those with the highest was 1.64 in men and 2.01 in women. The odds ratio in residents of provinces that had always been among those with the lowest GDPpc versus residents in provinces that had never been among those with lowest GDPpc was 1.54 in men and 1.91 in women. Neither the current Gini coefficient nor the indicator that reflects sustained high Gini coefficient were associated with physical inactivity. These findings show that physical inactivity is associated with current socioeconomic context and with the duration of exposure of the area of residence to adverse socioeconomic circumstances when the indicators of socioeconomic environment are based on GDPpc, but not on income inequality. Also, this association is not explained by individual socioeconomic characteristics or the number of sports facilities. PMID:17466424
Meskarpour-Amiri, Mohammad; Mehdizadeh, Parisa; Barouni, Mohsen; Dopeykar, Nooredin; Ramezanian, Maryam
2014-01-01
Background and Aim: While most of the published researches have reported the amount of inequity in geographical distribution of important health resources, only a small number of studies have focused on the trend of inequality in the distribution of these resources. The purpose of this study was to determine the trend of inequality in the distribution of intensive care beds in Iran during 2010 to 2012 by using the Gini coefficient. Methods: This is a cross-sectional research conducted in 2013. The changes over three years (2010 to 2012) were calculated by Gini coefficient to investigate the trend of inequality in geographical distribution of intensive care beds (CCU, ICU and NICU). Results: The Gini coefficient for CCU beds was calculated as 0.02, 0.04 and 0.06 in 2010, 2011 and 2012, respectively. The Gini coefficient for ICU beds was calculated as 0.03, 0.05 and 0.05 in 2010, 2011 and 2012, respectively. Also, the Gini coefficient for NICU bed was calculated as 0.02, 0.03 and 0.04 in 2010, 2011 and 2012, respectively. Conclusion: Regarding to Gini coefficient, the trend of inequality was increased in the distribution of intensive care beds in Iran. Particularly, the inequalities in distribution of CCU beds were significantly increased during past years. In fact, if this trend of inequality continues, the distribution of intensive care beds will be extremely unequal in the next five years in Iran. PMID:25363104
Against UNESCO: Gedda, Gini and American scientific racism.
Cassata, Francesco
2008-01-01
The aim of this article is to shed light on the ideological, institutional and intellectual connections between Italian eugenics and American scientific racism, from 1953 to 1967. The paper pays special attention to the scientific links between fascist demographer Corrado Gini (the first president of the Italian Central Statistical Institute - Istat), and geneticist Luigi Gedda (the president of the Gregor Mendel Institute in Rome and head of the Catholic political association Azione Cattolica) on the one hand, and on the other, the members of the IAAEE (International Association for the Advancement of Ethnology and Eugenics) and their journal, "The Mankind Quarterly". Corrado Gini and Luigi Gedda were both members of the honorary advisory board of "The Mankind Quarterly", and Gini was also assistant editor in 1962. Despite the theoretical differences between the "neo-Lamarckians" Gini and Gedda, and the "Mendelians" Robert Gayre and Reginald Ruggles Gates--editor and associate editor of "The Mankind Quarterly"--the relationship grew stronger because of a sort of strategic alliance in the ideological fight against UNESCO's Statements on Race. The main source of the paper is Corrado Gini's personal archive, deposited in Rome at the National State Archive (ACS). PMID:19848223
CORRADO GINI AND THE SCIENTIFIC BASIS OF FASCIST RACISM.
Macuglia, Daniele
2014-01-01
It is controversial whether the development of Fascist racism was influenced by earlier Italian eugenic research. Before the First International Eugenics Congress held in London in 1912, Italian eugenics was not characterized by a clear program of scientific research. With the advent of Fascism, however, the equality "number = strength" became the foundation of its program. This idea, according to which the improvement of a nation relies on the amplitude of its population, was conceived by statistician Corrado Gini (1884-1965) already in 1912. Focusing on the problem of the degeneration of the Italian race, Gini had a tremendous influence on Benito Mussolini's (1883-1945) political campaign, and shaped Italian social sciences for almost two decades. He was also a committed racist, as documented by a series of indisputable statements from the primary literature. All these findings place Gini in a linking position among early Italian eugenics, Fascism and official state racism. PMID:26292521
Gini covariance matrix and its affine equivariant version
NASA Astrophysics Data System (ADS)
Weatherall, Lauren Anne
Gini's mean difference (GMD) and its derivatives such as Gini index have been widely used as alternative measures of variability over one century in many research fields especially in finance, economics and social welfare. In this dissertation, we generalize the univariate GMD to the multivariate case and propose a new covariance matrix so called the Gini covariance matrix (GCM). The extension is natural, which is based on the covariance representation of GMD with the notion of multivariate spatial rank function. In order to gain the affine equivariance property for GCM, we utilize the transformation-retransformation (TR) technique and obtain TR version GCM that turns out to be a symmetrized M-functional. Indeed, both GCMs are symmetrized approaches based on the difference of two independent variables without reference of a location, hence avoiding some arbitrary definition of location for non-symmetric distributions. We study the properties of both GCMs. They possess the so-called independence property, which is highly important, for example, in independent component analysis. Influence functions of two GCMs are derived to assess their robustness. They are found to be more robust than the regular covariance matrix but less robust than Tyler and Dumbgen M-functional. Under elliptical distributions, the relationship between the scatter parameter and the two GCM are obtained. With this relationship, principal component analysis (PCA) based on GCM is possible. Estimation of two GCMs is presented. We study asymptotical behavior of the estimators. √n-consistency and asymptotical normality of estimators are established. Asymptotic relative efficiency (ARE) of TR-GCM estimator with respect to sample covariance matrix is compared to that of Tyler and Dumbgen M-estimators. With little loss on efficiency (< 2%) in the normal case, it gains high efficiency for heavy-tailed distributions. Finite sample behavior of Gini estimators is explored under various models using two
GINI: From ISH Images to Gene Interaction Networks
Puniyani, Kriti; Xing, Eric P.
2013-01-01
Accurate inference of molecular and functional interactions among genes, especially in multicellular organisms such as Drosophila, often requires statistical analysis of correlations not only between the magnitudes of gene expressions, but also between their temporal-spatial patterns. The ISH (in-situ-hybridization)-based gene expression micro-imaging technology offers an effective approach to perform large-scale spatial-temporal profiling of whole-body mRNA abundance. However, analytical tools for discovering gene interactions from such data remain an open challenge due to various reasons, including difficulties in extracting canonical representations of gene activities from images, and in inference of statistically meaningful networks from such representations. In this paper, we present GINI, a machine learning system for inferring gene interaction networks from Drosophila embryonic ISH images. GINI builds on a computer-vision-inspired vector-space representation of the spatial pattern of gene expression in ISH images, enabled by our recently developed system; and a new multi-instance-kernel algorithm that learns a sparse Markov network model, in which, every gene (i.e., node) in the network is represented by a vector-valued spatial pattern rather than a scalar-valued gene intensity as in conventional approaches such as a Gaussian graphical model. By capturing the notion of spatial similarity of gene expression, and at the same time properly taking into account the presence of multiple images per gene via multi-instance kernels, GINI is well-positioned to infer statistically sound, and biologically meaningful gene interaction networks from image data. Using both synthetic data and a small manually curated data set, we demonstrate the effectiveness of our approach in network building. Furthermore, we report results on a large publicly available collection of Drosophila embryonic ISH images from the Berkeley Drosophila Genome Project, where GINI makes novel and
Correlation between the Gini index and the observed prosperity
NASA Astrophysics Data System (ADS)
Mazin, Igor
2006-03-01
It has been well established by computer simulations that a free, unregulated market economy (in the simplest model of a yard sale economy) is unstable and collapses to a singular wealth distribution. It is now a common procedure in computer simulations to stabilize a model by favoring the poorer partner in each transaction, or by redistributing the wealth in the society in favor of the poorer part of the population. Such measures stabilize the economy and create a stationary state with a Gini index G<1. This suggests that there is some optimal range of the Gini index which is indicative of a healthy and dynamic economy. To verify this assumption, I plotted the PPP (parity purchasing power) for all countries in the world against their Gini indices, and found that they all (with only 2 outliers) fall into one of two groups: ``wealthy'' countries with PPP>10,000/year, and the rest. The former are characterized by G=0.29±0.07, and the latter by a uniform distribution of all possible Gs. This means that an enforced wealth redistribution is not a moral act of social consciousness, but a necessary precondition for a sustainable economy. The existence of an optimal G is illustrated through a simple model of a yard sale economy with taxation.
Feeding ducks, bacterial chemotaxis, and the Gini index
NASA Astrophysics Data System (ADS)
Peaudecerf, François J.; Goldstein, Raymond E.
2015-08-01
Classic experiments on the distribution of ducks around separated food sources found consistency with the "ideal free" distribution in which the local population is proportional to the local supply rate. Motivated by this experiment and others, we examine the analogous problem in the microbial world: the distribution of chemotactic bacteria around multiple nearby food sources. In contrast to the optimization of uptake rate that may hold at the level of a single cell in a spatially varying nutrient field, nutrient consumption by a population of chemotactic cells will modify the nutrient field, and the uptake rate will generally vary throughout the population. Through a simple model we study the distribution of resource uptake in the presence of chemotaxis, consumption, and diffusion of both bacteria and nutrients. Borrowing from the field of theoretical economics, we explore how the Gini index can be used as a means to quantify the inequalities of uptake. The redistributive effect of chemotaxis can lead to a phenomenon we term "chemotactic levelling," and the influence of these results on population fitness are briefly considered.
Using the gini coefficient to measure the chemical diversity of small-molecule libraries.
Weidlich, Iwona E; Filippov, Igor V
2016-08-15
Modern databases of small organic molecules contain tens of millions of structures. The size of theoretically available chemistry is even larger. However, despite the large amount of chemical information, the "big data" moment for chemistry has not yet provided the corresponding payoff of cheaper computer-predicted medicine or robust machine-learning models for the determination of efficacy and toxicity. Here, we present a study of the diversity of chemical datasets using a measure that is commonly used in socioeconomic studies. We demonstrate the use of this diversity measure on several datasets that were constructed to contain various congeneric subsets of molecules as well as randomly selected molecules. We also apply our method to a number of well-known databases that are frequently used for structure-activity relationship modeling. Our results show the poor diversity of the common sources of potential lead compounds compared to actual known drugs. © 2016 Wiley Periodicals, Inc. PMID:27353971
NASA Astrophysics Data System (ADS)
Khosravi Tanak, A.; Mohtashami Borzadaran, G. R.; Ahmadi, J.
2015-11-01
In economics and social sciences, the inequality measures such as Gini index, Pietra index etc., are commonly used to measure the statistical dispersion. There is a generalization of Gini index which includes it as special case. In this paper, we use principle of maximum entropy to approximate the model of income distribution with a given mean and generalized Gini index. Many distributions have been used as descriptive models for the distribution of income. The most widely known of these models are the generalized beta of second kind and its subclass distributions. The obtained maximum entropy distributions are fitted to the US family total money income in 2009, 2011 and 2013 and their relative performances with respect to generalized beta of second kind family are compared.
The Equivalence of Multiple Rater Kappa Statistics and Intraclass Correlation Coefficients.
ERIC Educational Resources Information Center
Rae, Gordon
1988-01-01
Using the Gini-Light-Margolin concept of "partioning" variance for qualitative data, correspondences are established between various kappa statistics and intraclass correlation coefficients under general conditions (multiple raters and polychotomous category systems). A measure of marginal symmetry for multiple ratings. (Author/TJH)
NASA Astrophysics Data System (ADS)
Preda, Vasile; Dedu, Silvia; Gheorghe, Carmen
2015-10-01
In this paper, by using the entropy maximization principle with Tsallis entropy, new distribution families for modeling the income distribution are derived. Also, new classes of Lorenz curves are obtained by applying the entropy maximization principle with Tsallis entropy, under mean and Gini index equality and inequality constraints.
Improving the accuracy of gene expression profile classification with Lorenz curves and Gini ratios.
Tran, Quoc-Nam
2011-01-01
Microarrays are a new technology with great potential to provide accurate medical diagnostics, help to find the right treatment for many diseases such as cancers, and provide a detailed genome-wide molecular portrait of cellular states. In this chapter, we show how Lorenz Curves and Gini Ratios can be modified to improve the accuracy of gene expression profile classification. Experimental results with different classification algorithms using additional techniques and strategies for improving the accuracy such as the principal component analysis, the correlation-based feature subset selection, and the consistency subset evaluation technique for the task of classifying lung adenocarcinomas from gene expression show that our method find more optimal genes than SAM. PMID:21431549
Inequality in societies, academic institutions and science journals: Gini and k-indices
NASA Astrophysics Data System (ADS)
Ghosh, Asim; Chattopadhyay, Nachiketa; Chakrabarti, Bikas K.
2014-09-01
Social inequality is traditionally measured by the Gini-index (g). The g-index takes values from 0 to 1 where g=0 represents complete equality and g=1 represents complete inequality. Most of the estimates of the income or wealth data indicate the g value to be widely dispersed across the countries of the world: g values typically range from 0.30 to 0.65 at a particular time (year). We estimated similarly the Gini-index for the citations earned by the yearly publications of various academic institutions and the science journals. The ISI web of science data suggests remarkably strong inequality and universality (g=0.70±0.07) across all the universities and institutions of the world, while for the journals we find g=0.65±0.15 for any typical year. We define a new inequality measure, namely the k-index, saying that the cumulative income or citations of (1-k) fraction of people or papers exceed those earned by the fraction (k) of the people or publications respectively. We find, while the k-index value for income ranges from 0.60 to 0.75 for income distributions across the world, it has a value around 0.75±0.05 for different universities and institutions across the world and around 0.77±0.10 for the science journals. Apart from above indices, we also analyze the same institution and journal citation data by measuring Pietra index and median index.
A methodology to determine the maximum value of weighted Gini-Simpson index.
Casquilho, José Pinto
2016-01-01
Weighted Gini-Simpson index is an analytical tool that promises to be widely used concerning biological and economics applications, relative to the assessment of diversity measured by compositional proportions of a system defined with a finite number of elementary states characterized by positive weights. In this paper, a current literature review on the theme is presented and the mathematical properties of the index are outlined, focusing on the location of the maximizer (maximum point) and evaluation of the maximum value, with emphasis in the role of the Lagrange multiplier critical value-closely related with the harmonic mean of the weights-which is shown to be a barrier concerning the feasibility of the solution. Sequential procedures are presented, either backward or forward, which are used to obtain the correct values of the maximum point coordinates, thus allowing for the computation of the right maximum value of the index. Also, new theoretical results are provided, such as the calculus of limits and partial derivatives related to the critical solution, used to assess of the effectiveness of the algorithms herein proposed and discussed. PMID:27504241
Murug, Waali, and Gini: Expressions of Distress in Refugees From Somalia
Carroll, Jennifer K.
2004-01-01
Objective: To study how mental illness is understood, expressed, and treated among Somali refugees and how these factors influence use of health services for mental problems. Method: Seventeen adult Somali refugees (9 women, 8 men) were recruited by mail or by word-of-mouth to participate in the study. The study setting was an urban community health center in Rochester, N.Y., that provides family practice patient care to local Somali refugees. A qualitative design was used that incorporated a combination of methods, chiefly semistructured interviews. Interviews focused on the ways in which sadness, depression, and anxiety are expressed and on the participants' understanding of the origins of and treatment strategies for these problems. Interview transcripts were analyzed to identify recurrent themes. Results: Nearly all participants felt that mental illness was a new problem for their community that did not exist to the same extent in prewar Somalia. Themes that emerged to explain the causes of mental illness included the shock and devastation of war; dead, missing, or separated family members; and spirit possession or a curse. Three major types of mental problems were identified that were associated with specific behaviors and treatment strategies: murug (sadness or suffering), gini (craziness due to spirit possession), and waali (craziness due to severe trauma). Rather than seek help from a clinician, participants preferred to first use family support, prayer, or traditional therapies for most situations. Conclusion: Somali refugees have distinct ways of conceptualizing, expressing, and treating commonly understood mental problems. Participants differed in their opinions about whether they would consult a doctor to discuss feelings of sadness or craziness. Effective mental health care of refugees should address culture-specific belief systems in diagnosis and treatment. PMID:15361926
NASA Astrophysics Data System (ADS)
Inoue, Jun-ichi; Ghosh, Asim; Chatterjee, Arnab; Chakrabarti, Bikas K.
2015-07-01
Social inequality manifested across different strata of human existence can be quantified in several ways. Here we compute non-entropic measures of inequality such as Lorenz curve, Gini index and the recently introduced k index analytically from known distribution functions. We characterize the distribution functions of different quantities such as votes, journal citations, city size, etc. with suitable fits, compute their inequality measures and compare with the analytical results. A single analytic function is often not sufficient to fit the entire range of the probability distribution of the empirical data, and fit better to two distinct functions with a single crossover point. Here we provide general formulas to calculate these inequality measures for the above cases. We attempt to specify the crossover point by minimizing the gap between empirical and analytical evaluations of measures. Regarding the k index as an 'extra dimension', both the lower and upper bounds of the Gini index are obtained as a function of the k index. This type of inequality relations among inequality indices might help us to check the validity of empirical and analytical evaluations of those indices.
Looking beyond Harlem: International Insights for Area-Based Initiatives
ERIC Educational Resources Information Center
Miller, Peter M.; Gibson, Jordi Diaz; Balslev, Gitte Miller; Scanlan, Martin
2012-01-01
Purposeful and strategic connections between schools, families, and communities are critical characteristics of effective middle level education. Area-based initiatives (ABIs) have been particularly visible family-school-community policy developments in recent years--especially the federally funded "Promise Neighborhoods," which attempt to…
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…
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…
Mapping ear canal movement using area-based surface matching
NASA Astrophysics Data System (ADS)
Grenness, Malcolm J.; Osborn, Jon; Weller, W. Lee
2002-02-01
Movement of the external ear canal, associated with jaw motion, relative to the concha region of the pinna has been studied. Pairs of open-jaw and closed-jaw impressions were taken of 14 ears from 10 subjects. Three-dimensional coordinate data were obtained from the concha and the anterior surface of the canal using a reflex microscope. Proprietary area-based matching software was used to evaluate distortion of the two surfaces between the two jaw positions. The canal data from each pair were placed into the same coordinate system with their respective concha regions aligned. Difference maps of the canal data were used to demonstrate the amount of anterior-posterior (A-P), superior-inferior (S-I), and medial-lateral (M-L) movement, relative to the concha, that occurred between the open- and closed-jaw impressions. The concha regions did not undergo significant deformation. The canal regions underwent varying amounts of deformation with all canals conforming within an rms of 136 μm across the entire surface. The majority of canals underwent significant movement relative to the concha. M-L movement ranged from +2.0 to -3.8 mm; eight canals moved laterally, five moved medially, and two showed no movement. S-I movement ranged from +3.7 to -2.7 mm; nine canals moved inferiorly, two moved superiorly, and three showed no movement. A-P movement ranged between +7.5 and -8.5 mm, with five canals moving anteriorly, three posteriorly, and four in a mixed fashion. This study has shown the variability of canal movement relative to the concha and does not support previous reports that suggest that the ear canal only widens with jaw opening.
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)
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.
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.
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…
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.
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.
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…
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...
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…
Area-Based Partnerships in Rural Poland: The Post-Accession Experience
ERIC Educational Resources Information Center
Furmankiewicz, Marek; Thompson, Nicola; Zielinska, Marta
2010-01-01
The paper examines the characteristics of area-based partnerships in rural Poland. It is based on the study of partnerships created after the accession to the European Union in 2004. Partnership structures have been rapidly adopted in rural Poland due to opportunities provided by the LEADER+ Pilot Programme. However, the research showed that…
Towards an Area-Based Curriculum? Creating Space for the City in Schools
ERIC Educational Resources Information Center
Facer, Keri; Thomas, Louise
2012-01-01
This paper uses Fraser's (1999) concept of social justice as comprising both redistribution and recognition as a frame to interrogate two "Area-Based Curriculum" projects running since 2008 in Manchester and Peterborough schools. It argues that historic concerns about working with "the local" in cross-curricular activities has originated in a…
Inequality in Academic Performance and Juvenile Convictions: An Area-Based Analysis
ERIC Educational Resources Information Center
Sabates, Ricardo; Feinstein, Leon; Shingal, Anirudh
2011-01-01
This paper focuses on the links between inequality in academic performance and juvenile conviction rates for violent crime, stealing from another person, burglary in a dwelling and racially motivated offences. We use area-based aggregate data to model this relationship. Our results show that, above and beyond impacts of absolute access to…
Wrong Signs in Regression Coefficients
NASA Technical Reports Server (NTRS)
McGee, Holly
1999-01-01
When using parametric cost estimation, it is important to note the possibility of the regression coefficients having the wrong sign. A wrong sign is defined as a sign on the regression coefficient opposite to the researcher's intuition and experience. Some possible causes for the wrong sign discussed in this paper are a small range of x's, leverage points, missing variables, multicollinearity, and computational error. Additionally, techniques for determining the cause of the wrong sign are given.
Fuel Temperature Coefficient of Reactivity
Loewe, W.E.
2001-07-31
A method for measuring the fuel temperature coefficient of reactivity in a heterogeneous nuclear reactor is presented. The method, which is used during normal operation, requires that calibrated control rods be oscillated in a special way at a high reactor power level. The value of the fuel temperature coefficient of reactivity is found from the measured flux responses to these oscillations. Application of the method in a Savannah River reactor charged with natural uranium is discussed.
Transport coefficients of heavy baryons
NASA Astrophysics Data System (ADS)
Tolos, Laura; Torres-Rincon, Juan M.; Das, Santosh K.
2016-08-01
We compute the transport coefficients (drag and momentum diffusion) of the low-lying heavy baryons Λc and Λb in a medium of light mesons formed at the later stages of high-energy heavy-ion collisions. We employ the Fokker-Planck approach to obtain the transport coefficients from unitarized baryon-meson interactions based on effective field theories that respect chiral and heavy-quark symmetries. We provide the transport coefficients as a function of temperature and heavy-baryon momentum, and analyze the applicability of certain nonrelativistic estimates. Moreover we compare our outcome for the spatial diffusion coefficient to the one coming from the solution of the Boltzmann-Uehling-Uhlenbeck transport equation, and we find a very good agreement between both calculations. The transport coefficients for Λc and Λb in a thermal bath will be used in a subsequent publication as input in a Langevin evolution code for the generation and propagation of heavy particles in heavy-ion collisions at LHC and RHIC energies.
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
Seebeck coefficient of one electron
Durrani, Zahid A. K.
2014-03-07
The Seebeck coefficient of one electron, driven thermally into a semiconductor single-electron box, is investigated theoretically. With a finite temperature difference ΔT between the source and charging island, a single electron can charge the island in equilibrium, directly generating a Seebeck effect. Seebeck coefficients for small and finite ΔT are calculated and a thermally driven Coulomb staircase is predicted. Single-electron Seebeck oscillations occur with increasing ΔT, as one electron at a time charges the box. A method is proposed for experimental verification of these effects.
Integer Solutions of Binomial Coefficients
ERIC Educational Resources Information Center
Gilbertson, Nicholas J.
2016-01-01
A good formula is like a good story, rich in description, powerful in communication, and eye-opening to readers. The formula presented in this article for determining the coefficients of the binomial expansion of (x + y)n is one such "good read." The beauty of this formula is in its simplicity--both describing a quantitative situation…
Prediction of stream volatilization coefficients
Rathbun, Ronald E.
1990-01-01
Equations are developed for predicting the liquid-film and gas-film reference-substance parameters for quantifying volatilization of organic solutes from streams. Molecular weight and molecular-diffusion coefficients of the solute are used as correlating parameters. Equations for predicting molecular-diffusion coefficients of organic solutes in water and air are developed, with molecular weight and molal volume as parameters. Mean absolute errors of prediction for diffusion coefficients in water are 9.97% for the molecular-weight equation, 6.45% for the molal-volume equation. The mean absolute error for the diffusion coefficient in air is 5.79% for the molal-volume equation. Molecular weight is not a satisfactory correlating parameter for diffusion in air because two equations are necessary to describe the values in the data set. The best predictive equation for the liquid-film reference-substance parameter has a mean absolute error of 5.74%, with molal volume as the correlating parameter. The best equation for the gas-film parameter has a mean absolute error of 7.80%, with molecular weight as the correlating parameter.
NASA Technical Reports Server (NTRS)
Chandra, N.
1974-01-01
Numerical coefficients required to express the angular distribution for the rotationally elastic or inelastic scattering of electrons from a diatomic molecule were tabulated for the case of nitrogen and in the energy range from 0.20 eV to 10.0 eV. Five different rotational states are considered.
Estimating the Polyserial Correlation Coefficient.
ERIC Educational Resources Information Center
Bedrick, Edward J.; Breslin, Frederick C.
1996-01-01
Simple noniterative estimators of the polyserial correlation coefficient are developed by exploiting a general relationship between the polyserial correlation and the point polyserial correlation to give extensions of the biserial estimators of K. Pearson (1909), H. E. Brogden (1949), and F. M. Lord (1963) to the multicategory setting. (SLD)
An Air-water Interfacial Area Based Variable Tortuosity Model for Unsaturated Sands
NASA Astrophysics Data System (ADS)
Khaleel, R.; Saripalli, P.
2005-12-01
A new variable tortuosity definition is introduced that is based on the immiscible fluid (air-water) interfacial area. Unsaturated media tortuosity (τa) is defined as the ratio of aaw to aaw,o where aaw is the estimated air-water interfacial area in a real unsaturated medium (i.e., a soil sample), and aaw,o is the same variable for the corresponding, idealized capillary bundle. We establish equivalence between the real and the idealized media by letting the laboratory-measured retention curve calculate the distribution of capillary tubes, thereby resulting in an identical pore-size distribution but a new retention curve for the idealized medium. The air-water interfacial area for both real and idealized media is directly proportional to the area under their respective retention curves. With τ being the saturated tortuosity, we relate the variable tortuosity ratio (ττa) to the Seɛ term in Mualem's (ɛ=0.5) and Burdine's (ɛ=2) pore-size distribution models. Thus, instead of using tortuosity and/or pore connectivity formulations that have empirical exponents of either 0.5 or 2, the new model depends on variable interfacial area for varying saturation and soil texture, as reflected in the measured retention data. We tested the new definition of tortuosity for 22 repacked Hanford sediments that are comprised of mostly coarse and fine sands but some also contain a sizeable fraction (as high as 27%) of fines (silt and clay). Replacing the Se2 term in van Genuchten-Mualem (VGM) model by the new interfacial area based variable tortuosity ratio, and still using saturated conductivity and retention parameters, as used in the conventional approach, we obtain interfacial area based K(θ) predictions that are nearly identical to the conventional VGM model predictions. We also compare the interfacial area based K(θ) predictions with the standard Brooks-Corey-Burdine (BCB) model predictions. Compared to the VGM model predictions, interfacial area based BCB K(θ) predictions
High temperature Seebeck coefficient metrology
Martin, J.; Tritt, T.; Uher, C.
2010-12-15
We present an overview of the challenges and practices of thermoelectric metrology on bulk materials at high temperature (300 to 1300 K). The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at high temperature. This has led to the implementation of nonideal practices that have further complicated the confirmation of reported high ZT materials. To ensure meaningful interlaboratory comparison of data, thermoelectric measurements must be reliable, accurate, and consistent. This article will summarize and compare the relevant measurement techniques and apparatus designs required to effectively manage uncertainty, while also providing a reference resource of previous advances in high temperature thermoelectric metrology.
Portable vapor diffusion coefficient meter
Ho, Clifford K.
2007-06-12
An apparatus for measuring the effective vapor diffusion coefficient of a test vapor diffusing through a sample of porous media contained within a test chamber. A chemical sensor measures the time-varying concentration of vapor that has diffused a known distance through the porous media. A data processor contained within the apparatus compares the measured sensor data with analytical predictions of the response curve based on the transient diffusion equation using Fick's Law, iterating on the choice of an effective vapor diffusion coefficient until the difference between the predicted and measured curves is minimized. Optionally, a purge fluid can forced through the porous media, permitting the apparatus to also measure a gas-phase permeability. The apparatus can be made lightweight, self-powered, and portable for use in the field.
Ionization coefficients in gas mixtures
NASA Astrophysics Data System (ADS)
Marić, D.; Šašić, O.; Jovanović, J.; Radmilović-Rađenović, M.; Petrović, Z. Lj.
2007-03-01
We have tested the application of the common E/N ( E—electric field, N—gas number density) or Wieland approximation [Van Brunt, R.J., 1987. Common parametrizations of electron transport, collision cross section, and dielectric strength data for binary gas mixtures. J. Appl. Phys. 61 (5), 1773-1787.] and the common mean energy (CME) combination of the data for pure gases to obtain ionization coefficients for mixtures. Test calculations were made for Ar-CH4, Ar-N2, He-Xe and CH4-N2 mixtures. Standard combination procedure gives poor results in general, due to the fact that the electron energy distribution is considerably different in mixtures and in individual gases at the same values of E/N. The CME method may be used for mixtures of gases with ionization coefficients that do not differ by more than two orders of magnitude which is better than any other technique that was proposed [Marić, D., Radmilović-Rađenović, M., Petrović, Z.Lj., 2005. On parametrization and mixture laws for electron ionization coefficients. Eur. Phys. J. D 35, 313-321.].
NASA Astrophysics Data System (ADS)
Xu, Qing; Hou, Zhengyang; Maltamo, Matti; Tokola, Timo
2014-07-01
Diameter distribution is essential for calculating stem volume and timber assortments of forest stands. A new method was proposed in this study to improve the estimation of stem volume and timber assortments, by means of combining the Area-based approach (ABA) and individual tree detection (ITD), the two main approaches to deriving forest attributes from airborne laser scanning (ALS) data. Two methods, replacement, and histogram matching were employed to calibrate ABA-derived diameter distributions with ITD-derived diameter estimates at plot level. The results showed that more accurate estimates were obtained when calibrations were applied. In view of the highest accuracy between ABA and ITD, calibrated diameter distributions decreased its relative RMSE of the estimated entire growing stock, saw log and pulpwood fractions by 2.81%, 3.05% and 7.73% points at best, respectively. Calibration improved pulpwood fraction significantly, which contributed to the negligible bias of the estimated entire growing stock.
Local-Area Based Traffic Splitter for Improving Performance Using Subnetting
NASA Astrophysics Data System (ADS)
Yadav, Meenakshi; Mittal, Mohit Kumar
2010-11-01
This document provides an overview of LAN traffic splitter. The tool "Local-Area based Traffic splitter" is based on subnetting techniques. It is basically used for calculating subnets for sub-dividing the LAN. Subnetting an IP Network can be done for a variety of reasons, including organization, use of different physical media (such as Ethernet, FDDI, WAN, etc.), preservation of address space, and security. The most common reason is to control network traffic. There are various techniques for calculating subnets that are considered by this tool. This paper will explore the various features of this tool and will also check the effect of subnetting after implementing it on the LAN. These instructions give you basic guidelines for preparing camera-ready papers for conference proceedings.
Shao, Huai-Yong; Wu, Jin-Hui; Liu, Meng; Yang, Wu-Nian
2014-01-01
It is an important research area to quantitatively studying the relationship between global climatic change and vegetation change based on the remote sensing technology. Panxi area is the ecological barrier of the upper reaches of the Yangtze River, and it is essential for the stability of the ecological environment of Sichuan as well as that of the whole China. The present article analyzes the vegetation change in 2001-2008 and the relationship between vegetation change and climatic variations of Panxi area, based on MODIS multispectral data and meteorological data. The results indicate that NDVI is positively correlated with temperature and precipitation. The precipitation is the major factor that affects the change of vegetation in the Panxi region and the trend of NDVI is similar with autumn precipitation; while at the same time the influence of climate has a one-month-time-lag. PMID:24783554
Area-Based Snow Damage Classification of Forest Canopies Using - Temporal LIDAR Data
NASA Astrophysics Data System (ADS)
Vastaranta, M.; Korpela, I.; Uotila, A.; Hovi, A.; Holopainen, M.
2011-09-01
Multitemporal LiDAR data provide means for mapping structural changes in forest canopies. We demonstrate the use of area-based estimation method for snow damage assessment. Change features of bi-temporal LiDAR point height distributions were used as predictors in combination with in situ training data. In the winter 2009-2010, snow damages occurred in Hyytiälä (62°N, 24°E), southern Finland. Snow load resulted in broken, bent and fallen trees changing the canopy structure. The damages were documented at the tree level at permanent field plots and dense LiDAR data from 2007 and 2010 were used in the analyses. A 5 × 5-m grid was established in one pine%ndash;spruce stand and change metrics from the LiDAR point height distribution were extracted for the cells. Cells were classified as damaged (n = 43) or undamaged (n = 42) based on the field data. Stepwise logistic regression detected the damaged cells with an overall accuracy of 78.6% (Kappa = 0.57). The best predictors were differences in h-distribution percentage points 5, 35, 40, 50 and 70 of first-or-single return data. The tentative results from the single stand suggest that dense bi-temporal LiDAR data and an area-based approach could be feasible in mapping canopy changes. The accuracy of the point h-distribution is dependent on the pulse density per grid cell. Depending on the time span between LiDAR acquisitions, the natural changes of the h- distributions due to tree growth need to be accounted for as well as differences in the scanning geometry, which can substantially affect the LiDAR h-metrics.
Measurements of thermal accommodation coefficients.
Rader, Daniel John; Castaneda, Jaime N.; Torczynski, John Robert; Grasser, Thomas W.; Trott, Wayne Merle
2005-10-01
A previously-developed experimental facility has been used to determine gas-surface thermal accommodation coefficients from the pressure dependence of the heat flux between parallel plates of similar material but different surface finish. Heat flux between the plates is inferred from measurements of temperature drop between the plate surface and an adjacent temperature-controlled water bath. Thermal accommodation measurements were determined from the pressure dependence of the heat flux for a fixed plate separation. Measurements of argon and nitrogen in contact with standard machined (lathed) or polished 304 stainless steel plates are indistinguishable within experimental uncertainty. Thus, the accommodation coefficient of 304 stainless steel with nitrogen and argon is estimated to be 0.80 {+-} 0.02 and 0.87 {+-} 0.02, respectively, independent of the surface roughness within the range likely to be encountered in engineering practice. Measurements of the accommodation of helium showed a slight variation with 304 stainless steel surface roughness: 0.36 {+-} 0.02 for a standard machine finish and 0.40 {+-} 0.02 for a polished finish. Planned tests with carbon-nanotube-coated plates will be performed when 304 stainless-steel blanks have been successfully coated.
Higher Order Macro Coefficients in Periodic Homogenization
NASA Astrophysics Data System (ADS)
Conca, Carlos; San Martin, Jorge; Smaranda, Loredana; Vanninathan, Muthusamy
2011-09-01
A first set of macro coefficients known as the homogenized coefficients appear in the homogenization of PDE on periodic structures. If energy is increased or scale is decreased, these coefficients do not provide adequate approximation. Using Bloch decomposition, it is first realized that the above coefficients correspond to the lowest energy and the largest scale. This naturally paves the way to introduce other sets of macro coefficients corresponding to higher energies and lower scales which yield better approximation. The next task is to compare their properties with those of the homogenized coefficients. This article reviews these developments along with some new results yet to be published.
Ratios of internal conversion coefficients
Raman, S.; Ertugrul, M.; Nestor, C.W. . E-mail: CNestorjr@aol.com; Trzhaskovskaya, M.B.
2006-03-15
We present here a database of available experimental ratios of internal conversion coefficients for different atomic subshells measured with an accuracy of 10% or better for a number of elements in the range 26 {<=} Z {<=} 100. The experimental set involves 414 ratios for pure and 1096 ratios for mixed-multipolarity nuclear transitions in the transition energy range from 2 to 2300 keV. We give relevant theoretical ratios calculated in the framework of the Dirac-Fock method with and without regard for the hole in the atomic subshell after conversion. For comparison, the ratios obtained within the relativistic Hartree-Fock-Slater approximation are also presented. In cases where several ratios were measured for the same transition in a given isotope in which two multipolarities were involved, we present the mixing ratio {delta} {sup 2} obtained by a least squares fit.
Evaluation of an Area-Based matching algorithm with advanced shape models
NASA Astrophysics Data System (ADS)
Re, C.; Roncella, R.; Forlani, G.; Cremonese, G.; Naletto, G.
2014-04-01
Nowadays, the scientific institutions involved in planetary mapping are working on new strategies to produce accurate high resolution DTMs from space images at planetary scale, usually dealing with extremely large data volumes. From a methodological point of view, despite the introduction of a series of new algorithms for image matching (e.g. the Semi Global Matching) that yield superior results (especially because they produce usually smooth and continuous surfaces) with lower processing times, the preference in this field still goes to well established area-based matching techniques. Many efforts are consequently directed to improve each phase of the photogrammetric process, from image pre-processing to DTM interpolation. In this context, the Dense Matcher software (DM) developed at the University of Parma has been recently optimized to cope with very high resolution images provided by the most recent missions (LROC NAC and HiRISE) focusing the efforts mainly to the improvement of the correlation phase and the process automation. Important changes have been made to the correlation algorithm, still maintaining its high performance in terms of precision and accuracy, by implementing an advanced version of the Least Squares Matching (LSM) algorithm. In particular, an iterative algorithm has been developed to adapt the geometric transformation in image resampling using different shape functions as originally proposed by other authors in different applications.
Solving the depth of the repeated texture areas based on the clustering algorithm
NASA Astrophysics Data System (ADS)
Xiong, Zhang; Zhang, Jun; Tian, Jinwen
2015-12-01
The reconstruction of the 3D scene in the monocular stereo vision needs to get the depth of the field scenic points in the picture scene. But there will inevitably be error matching in the process of image matching, especially when there are a large number of repeat texture areas in the images, there will be lots of error matches. At present, multiple baseline stereo imaging algorithm is commonly used to eliminate matching error for repeated texture areas. This algorithm can eliminate the ambiguity correspond to common repetition texture. But this algorithm has restrictions on the baseline, and has low speed. In this paper, we put forward an algorithm of calculating the depth of the matching points in the repeat texture areas based on the clustering algorithm. Firstly, we adopt Gauss Filter to preprocess the images. Secondly, we segment the repeated texture regions in the images into image blocks by using spectral clustering segmentation algorithm based on super pixel and tag the image blocks. Then, match the two images and solve the depth of the image. Finally, the depth of the image blocks takes the median in all depth values of calculating point in the bock. So the depth of repeated texture areas is got. The results of a lot of image experiments show that the effect of our algorithm for calculating the depth of repeated texture areas is very good.
The emission coefficient of uranium plasmas
NASA Technical Reports Server (NTRS)
Schneider, R. T.; Campbell, H. D.; Mack, J. M.
1973-01-01
The emission coefficient for uranium plasmas (Temperature: 8000 K) was measured for the wavelength range (200 A - 6000 A). The results are compared to theory and other measurements. The absorption coefficient for the same wavelength interval is also given.
M-Bonomial Coefficients and Their Identities
ERIC Educational Resources Information Center
Asiru, Muniru A.
2010-01-01
In this note, we introduce M-bonomial coefficients or (M-bonacci binomial coefficients). These are similar to the binomial and the Fibonomial (or Fibonacci-binomial) coefficients and can be displayed in a triangle similar to Pascal's triangle from which some identities become obvious.
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…
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…
NASA Technical Reports Server (NTRS)
Smith, Eric A.
2007-01-01
Most knowledge concerning the last century's climatology and climate dynamics of precipitation over the Mediterranean Sea basin is based on observations taken from rain gauges surrounding the sea itself. In turn, most of the observations come from Southern Europe, with many fewer measurements taken from widely scattered sites situated over North Africa, the Middle East, and the Balkans. This aspect of research on the Mediterranean Sea basin is apparent in a recent compilation of studies presented in book form concerning climate variability of the Mediterranean region [Lionello, P., P. Malanotte-Rizzoli, and R. Boscolo (eds.), 2006: Mediterranean Climate Variability. Elsevier, Amsterdam, 9 chapters.] In light of this missing link to over-water observations, this study (in conjunction with four companion studies by Z. Haddad, A. Mugnai, T. Nakazawa, and G. Stephens) will contrast the nature of precipitation variability directly over the Mediterranean Sea to precipitation variability over the surrounding land areas based on three decades of satellite-based precipitation estimates which have stood up well to validation scrutiny. The satellite observations are drawn from the Global Precipitation Climatology Project (GPCP) dataset extending back to 1979 and the TRMM Merged Algorithm 3b42 dataset extending back to 1998. Both datasets are mostly produced from microwave measurements, excepting the period from 1979 to mid-1987 when only infrared satellite measurements were available for the GPCP estimates. The purpose of this study is to emphasize how the salient properties of precipitation variability over land and sea across a hierarchy of space and time scales, and the salient differences in these properties, might be used in guiding short-term climate models to better predictions of future climate states under different regional temperature-change scenarios.
[Estimation of forest volume in Huzhong forest area based on RS, GIS and ANN].
Liu, Zhi-Hua; Chang, Yu; Chen, Hong-Wei
2008-09-01
Based on remote sensing (RS) which has integrated and realistic characteristics, geographic information system (GIS) which has powerful spatial analysis ability, and artificial neutral network (ANN) which can optimize nonlinear complex systems, the forest volume in Huzhong forest area was estimated. The results showed that there was an obvious negative correlation between the forest volume and infrared band, indicating that infrared band had definite potential in estimating forest volume. The forest volume also negatively correlated with visible band and PC1. Among the topographic factors, altitude exerted more influence than aspect and slope on the estimation of forest volume. The correlation coefficient of predicted value and actual value reached to 0.973, when the optimal ANN parameter, suitable GIS information, and RS bands were adopted. After principal component transformation, the amount of observation data was effectively reduced, while the predicted precision only had a small decline (R2 = 0.934). PMID:19102299
ERIC Educational Resources Information Center
Sedere, M. U.; Feldt, Leonard S.
1977-01-01
Two new reliability coefficients have been derived for situations in which a test must be divided into parts of unequal length. This report summarizes a study of the statistical bias and the standard errors of these coefficients and compares them to Guttman's lambda coefficients and Cronbach's alpha coefficient. (Author/JKS)
Gas-film coefficients for streams
Rathbun, R.E.; Tai, D.Y.
1983-01-01
Equations for predicting the gas-film coefficient for the volatilization of organic solutes from streams are developed. The film coefficient is a function of windspeed and water temperature. The dependence of the coefficient on windspeed is determined from published information on the evaporation of water from a canal. The dependence of the coefficient on temperature is determined from laboratory studies on the evaporation of water. Procedures for adjusting the coefficients for different organic solutes are based on the molecular diffusion coefficient and the molecular weight. The molecular weight procedure is easiest to use because of the availability of molecular weights. However, the theoretical basis of the procedure is questionable. The diffusion coefficient procedure is supported by considerable data. Questions, however, remain regarding the exact dependence of the film coefficint on the diffusion coefficient. It is suggested that the diffusion coefficient procedure with a 0.68-power dependence be used when precise estimate of the gas-film coefficient are needed and that the molecular weight procedure be used when only approximate estimates are needed.
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
Coupling coefficient of gain-guided lasers
NASA Technical Reports Server (NTRS)
Katz, J.; Kapon, E.; Lindsey, C.; Margalit, S.; Yariv, A.
1984-01-01
An analytical model is presented for the coupling coefficient for two gain-guided coupled waveguides, e.g., semiconductor laser arrays. A common parabolic gain distribution is assumed for the lasers, and the effective dielectric constant distribution is approximated in terms of the bulk refraction index, wavelength, power filling factor, and the antiguiding factor. The fundamental mode is then formulated and used in an integral for the coupling coefficient. The dependence of the coefficient of various waveguide parameters is described.
Computation of virial coefficients from integral equations.
Zhang, Cheng; Lai, Chun-Liang; Pettitt, B Montgomery
2015-06-01
A polynomial-time method of computing the virial coefficients from an integral equation framework is presented. The method computes the truncated density expansions of the correlation functions by series transformations, and then extracts the virial coefficients from the density components. As an application, the method was used in a hybrid-closure integral equation with a set of self-consistent conditions, which produced reasonably accurate virial coefficients for the hard-sphere fluid and Gaussian model in high dimensions. PMID:26049482
Computation of virial coefficients from integral equations
NASA Astrophysics Data System (ADS)
Zhang, Cheng; Lai, Chun-Liang; Pettitt, B. Montgomery
2015-06-01
A polynomial-time method of computing the virial coefficients from an integral equation framework is presented. The method computes the truncated density expansions of the correlation functions by series transformations, and then extracts the virial coefficients from the density components. As an application, the method was used in a hybrid-closure integral equation with a set of self-consistent conditions, which produced reasonably accurate virial coefficients for the hard-sphere fluid and Gaussian model in high dimensions.
Apparatus for measurement of coefficient of friction
NASA Technical Reports Server (NTRS)
Slifka, A. J.; Siegwarth, J. D.; Sparks, L. L.; Chaudhuri, Dilip K.
1990-01-01
An apparatus designed to measure the coefficient of friction in certain controlled atmospheres is described. The coefficient of friction observed during high-load tests was nearly constant, with an average value of 0.56. This value is in general agreement with that found in the literature and also with the initial friction coefficient value of 0.67 measured during self-mated friction of 440C steel in an oxygen environment.
Flood Hydrograph Restoration in Increasingly-urbanized Area Based on Low Elevation Greenbelt
NASA Astrophysics Data System (ADS)
GAO, Cheng; Yang, Tao
2015-04-01
In increasingly urbanized area, water surface ratio descends and storage capacity of water decreases rapidly associated with lakes, branches, wetlands and floodplains buried. In addition, land surface impermeability enlarges runoff coefficients and runoff velocity. Urban flood, with higher peak discharge, larger volume and shorter concentration time, brings higher risk than rural area. Flood hydrograph restoration is to restore the flood hydrograph after urbanization by specific strategies, by compensating water surface ratio (WSR) and pervious surface proportion (PSP) for peak attenuation, volume reduction and concentration time increase. This paper presents the equivalent effect of low elevation greenbelt- a type of low impact development practices and WSR, PSP by the model SWMM, based on which, the corresponding compensative water surface ratio (CWSR) and compensative pervious surface proportion (CPSP) were obtained according to the equal peak discharge, volume of flood and concentration time- the three parameters determining the flood hydrograph. Then a relationship was found out between the ratio of low elevation greenbelt and WSR, PSP. Finally, the just ratio of low elevation greenbelt and the amount of rainwater resource utilization can be got by comparison of flood hydrograph with the one before urbanization for the restoration based on the three parameters to reduce effect of urbanization on flood hydrograph.
Guan, Yan-long; Wang, Rang-hui; Li, Cheng; Yao, Jian; Zhang, Meng; Zhao, Jian-ping
2015-03-01
Based on the MODIS/MOD11A2 data from 2001 to 2013, this paper researched the characteristics of land surface temperature (LST) of Tianshan Mountains area. The results indicated that the average of LST in the study area was 1.73 °C , and LST was much higher in the east than in the west. The inter-annual variation range of LST in the northwest was significantly large than in other regions, with the largest above 0.55 °C in some areas. The LST tended to slowly increase with time, and the increase rate was 0.147 °C . a-1. It showed a significant seasonal difference, and the fluctuation of winter was significantly larger than in other seasons with the coefficient of variation reaching 12.7%. The LST difference of day time was greater than that at night, and that in summer was greater than in other seasons. The LST differed with land use types, and the fitted results were inconsistent between the LST and NDVI. With the increase of NDVI of woodland and grassland, the LST decreased dramatically. The LST of construction land and cropland under the influence of human activities had higher sensitivity with NDVI than other land types. PMID:26211048
NASA Astrophysics Data System (ADS)
Pavón-Domínguez, P.; Jiménez-Hornero, F. J.; Gutiérrez de Ravé, E.
2014-06-01
This study focuses on describing ozone patterns and estimating ozone concentrations in urban settings through the classification of an urban area into homogeneous typologies, according to hourly ozone concentrations, and the development of accurate estimation models for each typology. For these proposals, a hierarchical cluster analysis was conducted in order to define homogeneous subareas, and multiple linear regressions were subsequently applied with the aim of obtaining ozone predictions, employing chemical and meteorological variables as predictors. Seville metropolitan area (Spain) is a densely populated area of the Mediterranean Basin that exhibits environmental problems related to ozone pollution episodes. Ozone exceedances are a consequence of the combination of road traffic and industry emissions with hot temperatures and high solar radiation, mainly during anticyclonic events. Cluster analysis evince that this area can be divided into 3 categories according to hourly ozone concentration in summer. Cluster 1 is comprised of monitoring stations located in the outskirts of the city of Seville; Cluster 2 corresponds to monitoring stations located within the city of Seville; and Cluster 3 is comprised of a monitoring station specialized in traffic emissions. Multiple linear regression shows that the relative weight of meteorological variables decreases when moving from the urban periphery towards the urban center, whereas the weight of chemical variables increases. Coefficients of determination (R2) values were 0.885, 0.890 and 0.830 and root mean squared error (RMSE) were 11.226, 11.874 and 11.260 μg m-3 for Cluster 1, 2 and 3, respectively.
Commentary on Coefficient Alpha: A Cautionary Tale
ERIC Educational Resources Information Center
Green, Samuel B.; Yang, Yanyun
2009-01-01
The general use of coefficient alpha to assess reliability should be discouraged on a number of grounds. The assumptions underlying coefficient alpha are unlikely to hold in practice, and violation of these assumptions can result in nontrivial negative or positive bias. Structural equation modeling was discussed as an informative process both to…
Radiometer gives true absorption and emission coefficients
NASA Technical Reports Server (NTRS)
Fymat, A. L.
1977-01-01
Novel radiometer, unaffected by scattering and polarization, measures true absorption and emmission coefficients for arbitrary mixture of gases and polluting particles. It has potential astronomical, meteorological, and environmental applications, such as determination of radiative heat budget, aerosol relative concentration, and morphology of cloud, haze, and fog formations. Data and temperature can be coupled directly to small computer for online calculation of radiation coefficients.
On Burnett coefficients in periodic media
NASA Astrophysics Data System (ADS)
Conca, Carlos; Orive, Rafael; Vanninathan, Muthusamy
2006-03-01
The aim of this work is to demonstrate a curious property of general periodic structures. It is well known that the corresponding homogenized matrix is positive definite. We calculate here the next order Burnett coefficients associated with such structures. We prove that these coefficients form a tensor which is negative semidefinite. We also provide some examples showing degeneracy in multidimension.
Coefficient Alpha and Reliability of Scale Scores
ERIC Educational Resources Information Center
Almehrizi, Rashid S.
2013-01-01
The majority of large-scale assessments develop various score scales that are either linear or nonlinear transformations of raw scores for better interpretations and uses of assessment results. The current formula for coefficient alpha (a; the commonly used reliability coefficient) only provides internal consistency reliability estimates of raw…
Implications of NGA for NEHRP site coefficients
Borcherdt, Roger D.
2012-01-01
Three proposals are provided to update tables 11.4-1 and 11.4-2 of Minimum Design Loads for Buildings and Other Structures (7-10), by the American Society of Civil Engineers (2010) (ASCE/SEI 7-10), with site coefficients implied directly by NGA (Next Generation Attenuation) ground motion prediction equations (GMPEs). Proposals include a recommendation to use straight-line interpolation to infer site coefficients at intermediate values of ̅vs (average shear velocity). Site coefficients are recommended to ensure consistency with ASCE/SEI 7-10 MCER (Maximum Considered Earthquake) seismic-design maps and simplified site-specific design spectra procedures requiring site classes with associated tabulated site coefficients and a reference site class with unity site coefficients. Recommended site coefficients are confirmed by independent observations of average site amplification coefficients inferred with respect to an average ground condition consistent with that used for the MCER maps. The NGA coefficients recommended for consideration are implied directly by the NGA GMPEs and do not require introduction of additional models.
A gain-coefficient switched Alexandrite laser
NASA Astrophysics Data System (ADS)
Lee, Chris J.; van der Slot, Peter J. M.; Boller, Klaus-J.
2013-01-01
We report on a gain-coefficient switched Alexandrite laser. An electro-optic modulator is used to switch between high and low gain states by making use of the polarization dependent gain of Alexandrite. In gain-coefficient switched mode, the laser produces 85 ns pulses with a pulse energy of 240 mJ at a repetition rate of 5 Hz.
Diffusion coefficients of several aqueous alkanolamine solutions
Snijder, E.D.; Riele, M.J.M. te; Versteeg, G.F.; Swaaij, W.P.M. van . Dept. of Chemical Engineering)
1993-07-01
In absorption processes of acid gases (H[sub 2]S, CO[sub 2], COS) in alkanolamine solutions, diffusion coefficients are used for the calculation of the mass transfer rate. The Taylor dispersion technique was applied for the determination of diffusion coefficients of various systems. Experiments with the system KCl in water showed that the experimental setup provides accurate data. For the alkanolamines monoethanolamine (MEA), diethanolamine (DEA), methyldiethanolamine (MDEA), and di-2-propanolamine (DIPA), correlations for the diffusion coefficient as a function of temperature at different concentrations are given. A single relation for every amine has been derived which correlates the diffusion coefficients as a function of temperature and concentration. The temperature was varied between 298 and 348 K, and the concentration between 0 and 4000-5000 mol/m[sup 3]. Furthermore, a modified Stokes-Einstein relation is presented for the prediction of the diffusion coefficients in the alkanolamines in relation to the viscosity of the solvent and the diffusion coefficient at infinite dilution. The diffusion coefficients at low concentrations are compared with some available relations for the estimation of diffusion coefficients at infinite dilution, and it appears that the agreement is fairly good.
Coefficient Alpha Bootstrap Confidence Interval under Nonnormality
ERIC Educational Resources Information Center
Padilla, Miguel A.; Divers, Jasmin; Newton, Matthew
2012-01-01
Three different bootstrap methods for estimating confidence intervals (CIs) for coefficient alpha were investigated. In addition, the bootstrap methods were compared with the most promising coefficient alpha CI estimation methods reported in the literature. The CI methods were assessed through a Monte Carlo simulation utilizing conditions…
Calculator program set up for film coefficients
Gracey, J.O.; Teter, D.L.
1982-11-15
Describes a mechanized computation scheme for the film coefficients used in heat transfer calculations designed for the Texas Instruments TI-59 programmable calculator. Presents tables showing application conditions (small diagram included) and the corresponding heat transfer equations for 10 heat flow situations; symbols used; user instructions, a complete film coefficient program; and storage assignments. Example problem and corresponding printout are given.
Code System to Calculate Correlation & Regression Coefficients.
Energy Science and Technology Software Center (ESTSC)
1999-11-23
Version 00 PCC/SRC is designed for use in conjunction with sensitivity analyses of complex computer models. PCC/SRC calculates the partial correlation coefficients (PCC) and the standardized regression coefficients (SRC) from the multivariate input to, and output from, a computer model.
An agreement coefficient for image comparison
Ji, L.; Gallo, K.
2006-01-01
Combination of datasets acquired from different sensor systems is necessary to construct a long time-series dataset for remotely sensed land-surface variables. Assessment of the agreement of the data derived from various sources is an important issue in understanding the data continuity through the time-series. Some traditional measures, including correlation coefficient, coefficient of determination, mean absolute error, and root mean square error, are not always optimal for evaluating the data agreement. For this reason, we developed a new agreement coefficient for comparing two different images. The agreement coefficient has the following properties: non-dimensional, bounded, symmetric, and distinguishable between systematic and unsystematic differences. The paper provides examples of agreement analyses for hypothetical data and actual remotely sensed data. The results demonstrate that the agreement coefficient does include the above properties, and therefore is a useful tool for image comparison. ?? 2006 American Society for Photogrammetry and Remote Sensing.
Justification for change in AXAIR dispersion coefficients
Simpkins, A.A.
1994-02-01
AXAIR is the primary dose assessment code used at the Savannah River Site (SRS) to predict doses following hypothetical releases of relatively short durations. The atmospheric dispersion coefficients currently used in AXAIR are analytical expressions developed to fit the curves in the Turner Workbook as referred to in USNRC Regulatory Guide 1.145. This report explores the ramifications and benefits of changing the dispersion coefficients to a combination of Pasquill`s lateral dispersion coefficients and Briggs` vertical dispersion coefficients. The differences in the dispersion coefficients have a minor effect on the relative air concentrations for stability classes A--D, but a significant difference is seen for classes E, F, and G.
Analytic structure of one-loop coefficients
NASA Astrophysics Data System (ADS)
Feng, Bo; Wang, Honghui
2013-05-01
By the unitarity cut method, analytic expressions of one-loop coefficients have been given in spinor forms. In this paper, we present one-loop coefficients of various bases in Lorentz-invariant contraction forms of external momenta. Using these forms, the analytic structure of these coefficients becomes manifest. Firstly, coefficients of bases contain only second-type singularities while the first-type singularities are included inside scalar bases. Secondly, the highest degree of each singularity is correlated with the degree of the inner momentum in the numerator. Thirdly, the same singularities will appear in different coefficients, thus our explicit results could be used to provide a clear physical picture under various limits (such as soft or collinear limits) when combining contributions from all bases.
ERIC Educational Resources Information Center
Green, Samuel B.; Yang, Yanyun
2015-01-01
In the lead article, Davenport, Davison, Liou, & Love demonstrate the relationship among homogeneity, internal consistency, and coefficient alpha, and also distinguish among them. These distinctions are important because too often coefficient alpha--a reliability coefficient--is interpreted as an index of homogeneity or internal consistency.…
Wang, Junmei; Hou, Tingjun
2012-05-25
It is of great interest in modern drug design to accurately calculate the free energies of protein-ligand or nucleic acid-ligand binding. MM-PBSA (molecular mechanics Poisson-Boltzmann surface area) and MM-GBSA (molecular mechanics generalized Born surface area) have gained popularity in this field. For both methods, the conformational entropy, which is usually calculated through normal-mode analysis (NMA), is needed to calculate the absolute binding free energies. Unfortunately, NMA is computationally demanding and becomes a bottleneck of the MM-PB/GBSA-NMA methods. In this work, we have developed a fast approach to estimate the conformational entropy based upon solvent accessible surface area calculations. In our approach, the conformational entropy of a molecule, S, can be obtained by summing up the contributions of all atoms, no matter they are buried or exposed. Each atom has two types of surface areas, solvent accessible surface area (SAS) and buried SAS (BSAS). The two types of surface areas are weighted to estimate the contribution of an atom to S. Atoms having the same atom type share the same weight and a general parameter k is applied to balance the contributions of the two types of surface areas. This entropy model was parametrized using a large set of small molecules for which their conformational entropies were calculated at the B3LYP/6-31G* level taking the solvent effect into account. The weighted solvent accessible surface area (WSAS) model was extensively evaluated in three tests. For convenience, TS values, the product of temperature T and conformational entropy S, were calculated in those tests. T was always set to 298.15 K through the text. First of all, good correlations were achieved between WSAS TS and NMA TS for 44 protein or nucleic acid systems sampled with molecular dynamics simulations (10 snapshots were collected for postentropy calculations): the mean correlation coefficient squares (R²) was 0.56. As to the 20 complexes, the TS
Spreading coefficients of aliphatic hydrocarbons on water
Takii, Taichi; Mori, Y.H. . Dept. of Mechanical Engineering)
1993-11-01
Experiments have been performed to determine the equilibrium spreading coefficients of some aliphatic hydrocarbons (C[sub 6]C[sub 10]) on water. The thickness of a discrete lens of each hydrocarbon sample floating on a stagnant water pool was measured interferometrically and used to calculate the spreading coefficient of the hydrocarbon with the aid of Langmuir's capillarity theory. The dependences of the spreading coefficient, thus observed, on temperature (0--50 C) and on the number of carbon atoms in the hydrocarbon molecule are in qualitative agreement with the predictions based on the Lifshitz theory of van der Waals forces.
On the emission coefficient of uranium plasmas.
NASA Technical Reports Server (NTRS)
Schneider, R. T.; Campbell, H. D.; Mack, J. M.
1973-01-01
The emission coefficient for uranium plasmas (temperature: 8000 K) was measured for the wavelength range from 1200 to 6000 A. The results were compared to theoretical calculations and other measurements. Reasonable agreement between theoretical predictions and our measurements was found in the region from 1200 to 2000 A. Although it was difficult to make absolute comparisons among the different reported measurements, considerable disagreement was found for the higher wavelength region. A short discussion regarding the overall comparisons is given, and final suggestions are made as to the most appropriate emission coefficient values to be used in future design calculations. The absorption coefficient for the same wavelength interval is also reported.
Determination of absorption coefficients of thin films
Lodenquai, J.F. )
1994-08-01
The equations that are usually presented as those used to determine the absorption coefficients of materials in film form based on measurements of transmission and reflection coefficients are fundamentally incorrect. These equations omit a multiplicative factor arising from the complex nature of the refractive indices of the materials. This factor enters explicitly into the relationship between the transmission and reflection coefficients for such materials and is not necessarily close to unity, although in practice this factor can be approximated by unity at least in the infrared through the optical range of wavelengths.
Diffuse reflection coefficient of a stratified sea.
Haltrin, V I
1999-02-20
A differential equation of a Riccati type for the diffuse reflection coefficient of a stratified sea is proposed. For a homogeneous sea with arbitrary inherent optical properties this equation is solved analytically. For an inhomogeneous sea it is solved approximately for any arbitrary stratification. The resulting equation expresses the diffuse reflection coefficient of the sea through vertical profiles of absorption and backscattering coefficients, bottom albedo, and sea depth. The results of calculations with this equation are compared with Monte Carlo computations. It was found that the precision of this approach is in the range of 15%. PMID:18305694
Generalized Coefficients for Hopf Cyclic Cohomology
NASA Astrophysics Data System (ADS)
Hassanzadeh, Mohammad; Kucerovsky, Dan; Rangipour, Bahram
2014-09-01
A category of coefficients for Hopf cyclic cohomology is defined. It is shown that this category has two proper subcategories of which the smallest one is the known category of stable anti Yetter-Drinfeld modules. The middle subcategory is comprised of those coefficients which satisfy a generalized SAYD condition depending on both the Hopf algebra and the (co)algebra in question. Some examples are introduced to show that these three categories are different. It is shown that all components of Hopf cyclic cohomology work well with the new coefficients we have defined.
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
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.
Universal relations of transport coefficients from holography
Cherman, Aleksey; Nellore, Abhinav
2009-09-15
We show that there are universal high-temperature relations for transport coefficients of plasmas described by a wide class of field theories with gravity duals. These theories can be viewed as strongly coupled large-N{sub c} conformal field theories deformed by one or more relevant operators. The transport coefficients we study are the speed of sound and bulk viscosity, as well as the conductivity, diffusion coefficient, and charge susceptibility of probe U(1) charges. We show that the sound bound v{sub s}{sup 2}{<=}1/3 is satisfied at high temperatures in these theories and also discuss bounds on the diffusion coefficient, the conductivity, and the bulk viscosity.
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.
Friction coefficient dependence on electrostatic tribocharging
Burgo, Thiago A. L.; Silva, Cristiane A.; Balestrin, Lia B. S.; Galembeck, Fernando
2013-01-01
Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers. PMID:23934227
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.
On computing Laplace's coefficients and their derivatives.
NASA Astrophysics Data System (ADS)
Gerasimov, I. A.; Vinnikov, E. L.
The algorithm of computing Laplace's coefficients and their derivatives is proposed with application of recurrent relations. The A.G.M.-method is used for the calculation of values L0(0), L0(1). The FORTRAN-program corresponding to the algorithm is given. The precision control was provided with numerical integrating by Simpsons method. The behavior of Laplace's coefficients and their third derivatives whith varying indices K, n for fixed values of the α-parameter is presented graphically.
Experimental Mg IX photorecombination rate coefficient
NASA Astrophysics Data System (ADS)
Schippers, S.; Schnell, M.; Brandau, C.; Kieslich, S.; Müller, A.; Wolf, A.
2004-07-01
The rate coefficient for radiative and dielectronic recombination of beryllium-like magnesium ions was measured with high resolution at the Heidelberg heavy-ion storage ring TSR. In the electron-ion collision energy range 0-207 eV resonances due to 2s -> 2p (Δ N = 0) and 2s -> 3l (Δ N=1) core excitations were detected. At low energies below 0.15 eV the recombination rate coefficient is dominated by strong 1s2 (2s 2p 3P) 7l resonances with the strongest one occuring at an energy of only 21 meV. These resonances decisively influence the Mg IX recombination rate coefficient in a low temperature plasma. The experimentally derived Mg IX dielectronic recombination rate coefficient (±15% systematical uncertainty) is compared with the recommendation by Mazzotta et al. (1998, A&AS, 133, 403) and the recent calculations by Gu (2003, ApJ, 590, 1131) and by Colgan et al. (2003, A&A, 412, 597). These results deviate from the experimental rate coefficient by 130%, 82% and 25%, respectively, at the temperature where the fractional abundance of Mg IX is expected to peak in a photoionized plasma. At this temperature a theoretical uncertainty in the 1s2 (2s 2p 3P) 7l resonance positions of only 100 meV would translate into an uncertainty of the plasma rate coefficient of almost a factor 3. This finding emphasizes that an accurate theoretical calculation of the Mg IX recombination rate coefficient from first principles is challenging.
Quantitative Ultrasound Imaging Using Acoustic Backscatter Coefficients.
NASA Astrophysics Data System (ADS)
Boote, Evan Jeffery
Current clinical ultrasound scanners render images which have brightness levels related to the degree of backscattered energy from the tissue being imaged. These images offer the interpreter a qualitative impression of the scattering characteristics of the tissue being examined, but due to the complex factors which affect the amplitude and character of the echoed acoustic energy, it is difficult to make quantitative assessments of scattering nature of the tissue, and thus, difficult to make precise diagnosis when subtle disease effects are present. In this dissertation, a method of data reduction for determining acoustic backscatter coefficients is adapted for use in forming quantitative ultrasound images of this parameter. In these images, the brightness level of an individual pixel corresponds to the backscatter coefficient determined for the spatial position represented by that pixel. The data reduction method utilized rigorously accounts for extraneous factors which affect the scattered echo waveform and has been demonstrated to accurately determine backscatter coefficients under a wide range of conditions. The algorithms and procedures used to form backscatter coefficient images are described. These were tested using tissue-mimicking phantoms which have regions of varying scattering levels. Another phantom has a fat-mimicking layer for testing these techniques under more clinically relevant conditions. Backscatter coefficient images were also formed of in vitro human liver tissue. A clinical ultrasound scanner has been adapted for use as a backscatter coefficient imaging platform. The digital interface between the scanner and the computer used for data reduction are described. Initial tests, using phantoms are presented. A study of backscatter coefficient imaging of in vivo liver was performed using several normal, healthy human subjects.
Composite Transport Coefficient for Electron Thermal Energy
NASA Astrophysics Data System (ADS)
Coppi, B.; Daughton, W.
1996-11-01
A series of experiments by the Alcator C-Mod machine over a range of heating conditions (ohmic to strongly r.f. heated) has led to the construction of a composite transport coefficient for the electron thermal energy. This is represented by the difference of two terms: one corresponding to an outflow of thermal energy and the other one corresponding to an inflow. There are theoretical arguments(B. Coppi and F. Pegoraro, Phys. Fluids B) 3 p. 2582 (1991) in support of a composite transport coefficient involving the elements of a transport matrix with an inflow term related for instance to the features of the current density profile relative to those of the electron temperature. In deriving the transport coefficient D_e^th that has been used to simulate the Alcator C-Mod plasmas, we have assumed that the driving factor of the underlying modes is the plasma pressure gradient. Thus D_e^th ∝ D_e^o [β_p* - C] where β_p* = (8π p* / B_p^2), p* ≡ -r(dp/dr) is evaluated at the point of maximum pressure gradient, C ≈ 3/16 is a positive numerical coefficient and D_e^o ∝ I_p/(nT)^5/6 is basically the Coppi-Mazzucato-Gruber diffusion coefficient introduced earlier to reproduce the results of experiments with ohmic heating. Supported in part by the U.S. Department of Energy
Estimation of soil sorption coefficients using QSARs
Doucette, W.J.
1994-12-31
Sorption coefficients quantitatively describe the extent to which an organic chemical distributes itself between an environmental solid and the aqueous phase that it is contact with at equilibrium. Because of the difficulty and expense associated with measuring sorption coefficients, estimated values are often used in place of site specific, experimental values for fate modeling. Most reported methods for estimating the sorption of organic chemicals onto environmental solids are based on observation that for many organic chemicals, and in particular neutral hydrophobic organics, sorption is directly proportional to the quantity of organic matter associated with the solid. Normalizing soil or sediment specific sorption coefficients to the organic carbon content of the sorbent yields a new ``constant``, Koc, that is considered unique property of the organic chemical being sorbed. Values of Koc are then typically estimated from correlations between Koc and various descriptors of hydrophobicity such as octanol/water partition coefficients (Kow), aqueous solubility (S), molecular connectivity indices (MCIs) and retention times or capacity factors generated by reverse phase high performance liquid chromatography (RP-HPLC). Group contribution methods have also been described. While the so-called ``Koc approach`` for estimating sorption coefficients is most appropriate for neutral, hydrophobic organic chemicals on environmental solids containing a significant amount of organic matter, it has been applied to a wide variety of chemical and soil types. This presentation will focus on a discussion of the Koc approach, its applicability and limitations. A comparison of several widely used methods for estimating Koc will be presented.
Understanding correlation coefficients in treaty verification
DeVolpi, A.
1991-11-01
When a pair of images are compared on a point-by-point basis, the linear-correlation coefficient is usually used as a measure of similarity or dissimilarity. This paper evaluates the theoretical underpinnings and limitation of the linear-correlation coefficient, as well as other related statistics, particularly for cases where inherent white noise is present. As a result of the limitations in linear-correlation, an additional step has been derived -- local-sum clustering -- in order to improve recognition of small dissimilarities in a pair images. Results show that three-stage procedure, consisting of first establishing congruence of the two images, than using the linear-correlation coefficient as a test of true negatives, and finally qualifying a true positive by using the cluster (local-sum) method. These algorithmic stages would be especially useful in arms control treaty verification.
Temperature coefficients of multijunction solar cells
NASA Technical Reports Server (NTRS)
Virshup, G. F.; Chung, B.-C.; Ladle Ristow, M.; Kuryla, M. S.; Brinker, D.
1990-01-01
Temperature coefficients measured in solar simulators with those measured under AM0 solar illumination are compared to illustrate the challenges in making these measurements. It is shown that simulator measurements of the short-circuit current (delta Jsc/delta T) are inaccurate due to the mismatch between the solar spectrum and the simulators at the bandgaps of the solar cells. Especially susceptible to error is the delta Jsc/delta T of cells which are components in monolithic multijunction solar cells, such as GaAs filtered by 1.93-eV AlGaAs, which has an AM0 coefficient of 6.82 micro-A/sq cm/deg C, compared to a Xenon simulator coefficient of 22.2 micro-A/sq cm/deg C.
Improved Diffusion Coefficients for Stellar Plasmas
NASA Astrophysics Data System (ADS)
Brassard, P.; Fontaine, G.
2014-04-01
We are currently working on the fourth generation of our codes for building evolutionary and static models of hot subdwarf and white dwarf stars. One of the improvements of these codes consists in an update of all the microphysics involved in the computations. As part of our efforts, we have taken a look at possible improvements for the diffusion coefficients. Since the publication of the widely used diffusion coefficients of Paquette et al. (1986), the number-crunching power of computers has immensely increased, allowing more accurate computations of the triple collision integrals. We have thus produced new tables of diffusion coefficients with higher accuracy and higher resolution than before, of general use in stellar astrophysics.
Yoneoka, Daisuke; Saito, Eiko; Nakaoka, Shinji
2016-01-01
To optimally allocate health resources, policy planners require an indicator reflecting the inequality. Currently, health inequalities are frequently measured by area-based indices. However, methodologies for constructing the indices have been hampered by two difficulties: 1) incorporating the geographical relationship into the model and 2) selecting appropriate variables from the high-dimensional census data. Here, we constructed a new area-based health coverage index using the geographical information and a variable selection procedure with the example of gastric cancer. We also characterized the geographical distribution of health inequality in Japan. To construct the index, we proposed a methodology of a geographically weighted logistic lasso model. We adopted a geographical kernel and selected the optimal bandwidth and the regularization parameters by a two-stage algorithm. Sensitivity was checked by correlation to several cancer mortalities/screening rates. Lastly, we mapped the current distribution of health inequality in Japan and detected unique predictors at sampled locations. The interquartile range of the index was 0.0001 to 0.354 (mean: 0.178, SD: 0.109). The selections from 91 candidate variables in Japanese census data showed regional heterogeneities (median number of selected variables: 29). Our index was more correlated to cancer mortalities/screening rates than previous index and revealed several geographical clusters with unique predictors. PMID:27215347
Oka, Masayoshi; Wong, David W S
2016-06-01
Area-based measures of neighborhood characteristics simply derived from enumeration units (e.g., census tracts or block groups) ignore the potential of spatial spillover effects, and thus incorporating such measures into multilevel regression models may underestimate the neighborhood effects on health. To overcome this limitation, we describe the concept and method of areal median filtering to spatialize area-based measures of neighborhood characteristics for multilevel regression analyses. The areal median filtering approach provides a means to specify or formulate "neighborhoods" as meaningful geographic entities by removing enumeration unit boundaries as the absolute barriers and by pooling information from the neighboring enumeration units. This spatializing process takes into account for the potential of spatial spillover effects and also converts aspatial measures of neighborhood characteristics into spatial measures. From a conceptual and methodological standpoint, incorporating the derived spatial measures into multilevel regression analyses allows us to more accurately examine the relationships between neighborhood characteristics and health. To promote and set the stage for informative research in the future, we provide a few important conceptual and methodological remarks, and discuss possible applications, inherent limitations, and practical solutions for using the areal median filtering approach in the study of neighborhood effects on health. PMID:27197736
Yoneoka, Daisuke; Saito, Eiko; Nakaoka, Shinji
2016-01-01
To optimally allocate health resources, policy planners require an indicator reflecting the inequality. Currently, health inequalities are frequently measured by area-based indices. However, methodologies for constructing the indices have been hampered by two difficulties: 1) incorporating the geographical relationship into the model and 2) selecting appropriate variables from the high-dimensional census data. Here, we constructed a new area-based health coverage index using the geographical information and a variable selection procedure with the example of gastric cancer. We also characterized the geographical distribution of health inequality in Japan. To construct the index, we proposed a methodology of a geographically weighted logistic lasso model. We adopted a geographical kernel and selected the optimal bandwidth and the regularization parameters by a two-stage algorithm. Sensitivity was checked by correlation to several cancer mortalities/screening rates. Lastly, we mapped the current distribution of health inequality in Japan and detected unique predictors at sampled locations. The interquartile range of the index was 0.0001 to 0.354 (mean: 0.178, SD: 0.109). The selections from 91 candidate variables in Japanese census data showed regional heterogeneities (median number of selected variables: 29). Our index was more correlated to cancer mortalities/screening rates than previous index and revealed several geographical clusters with unique predictors. PMID:27215347
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.
Shear viscosity coefficient of liquid lanthanides
Patel, H. P. Thakor, P. B. Prajapati, A. V.; Sonvane, Y. A.
2015-05-15
Present paper deals with the computation of shear viscosity coefficient (η) of liquid lanthanides. The effective pair potential v(r) is calculated through our newly constructed model potential. The Pair distribution function g(r) is calculated from PYHS reference system. To see the influence of local field correction function, Hartree (H), Tailor (T) and Sarkar et al (S) local field correction function are used. Present results are compared with available experimental as well as theoretical data. Lastly, we found that our newly constructed model potential successfully explains the shear viscosity coefficient (η) of liquid lanthanides.
Virial expansion coefficients in the harmonic approximation.
Armstrong, J R; Zinner, N T; Fedorov, D V; Jensen, A S
2012-08-01
The virial expansion method is applied within a harmonic approximation to an interacting N-body system of identical fermions. We compute the canonical partition functions for two and three particles to get the two lowest orders in the expansion. The energy spectrum is carefully interpolated to reproduce ground-state properties at low temperature and the noninteracting high-temperature limit of constant virial coefficients. This resembles the smearing of shell effects in finite systems with increasing temperature. Numerical results are discussed for the second and third virial coefficients as functions of dimension, temperature, interaction, and transition temperature between low- and high-energy limits. PMID:23005730
Huge Seebeck coefficients in nonaqueous electrolytes
NASA Astrophysics Data System (ADS)
Bonetti, M.; Nakamae, S.; Roger, M.; Guenoun, P.
2011-03-01
The Seebeck coefficients of the nonaqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide, and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol, and ethylene-glycol are measured in a temperature range from T = 30 °C to T = 45 °C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here we report huge values of 7 mV/K at 0.1 M concentration for tetrabutylammonium nitrate in 1-dodecanol. These striking results open the question of unexpectedly large kosmotrope or "structure making" effects of tetraalkylammonium ions on the structure of alcohols.
ERIC Educational Resources Information Center
Mohammed, Ahmed; Zeleke, Aklilu
2015-01-01
We introduce a class of second-order ordinary differential equations (ODEs) with variable coefficients whose closed-form solutions can be obtained by the same method used to solve ODEs with constant coefficients. General solutions for the homogeneous case are discussed.
Bitplane Image Coding With Parallel Coefficient Processing.
Auli-Llinas, Francesc; Enfedaque, Pablo; Moure, Juan C; Sanchez, Victor
2016-01-01
Image coding systems have been traditionally tailored for multiple instruction, multiple data (MIMD) computing. In general, they partition the (transformed) image in codeblocks that can be coded in the cores of MIMD-based processors. Each core executes a sequential flow of instructions to process the coefficients in the codeblock, independently and asynchronously from the others cores. Bitplane coding is a common strategy to code such data. Most of its mechanisms require sequential processing of the coefficients. The last years have seen the upraising of processing accelerators with enhanced computational performance and power efficiency whose architecture is mainly based on the single instruction, multiple data (SIMD) principle. SIMD computing refers to the execution of the same instruction to multiple data in a lockstep synchronous way. Unfortunately, current bitplane coding strategies cannot fully profit from such processors due to inherently sequential coding task. This paper presents bitplane image coding with parallel coefficient (BPC-PaCo) processing, a coding method that can process many coefficients within a codeblock in parallel and synchronously. To this end, the scanning order, the context formation, the probability model, and the arithmetic coder of the coding engine have been re-formulated. The experimental results suggest that the penalization in coding performance of BPC-PaCo with respect to the traditional strategies is almost negligible. PMID:26441420
Problems on Divisibility of Binomial Coefficients
ERIC Educational Resources Information Center
Osler, Thomas J.; Smoak, James
2004-01-01
Twelve unusual problems involving divisibility of the binomial coefficients are represented in this article. The problems are listed in "The Problems" section. All twelve problems have short solutions which are listed in "The Solutions" section. These problems could be assigned to students in any course in which the binomial theorem and Pascal's…
Coefficient Omega Bootstrap Confidence Intervals: Nonnormal Distributions
ERIC Educational Resources Information Center
Padilla, Miguel A.; Divers, Jasmin
2013-01-01
The performance of the normal theory bootstrap (NTB), the percentile bootstrap (PB), and the bias-corrected and accelerated (BCa) bootstrap confidence intervals (CIs) for coefficient omega was assessed through a Monte Carlo simulation under conditions not previously investigated. Of particular interests were nonnormal Likert-type and binary items.…
Transport coefficients for electrons in Hg vapor
NASA Astrophysics Data System (ADS)
Dujko, Sasa; White, Ron; Petrovic, Zoran
2012-06-01
Transport coefficients and distribution functions are calculated for electrons in Hg vapor under swarm conditions using a multi term theory for solving the Boltzmann equation, over a range of E/N values and temperatures relevant to lamp discharges. It is shown that for higher E/N the electron distribution is non-thermal for all Hg vapor temperatures considered, and that the speed distribution function significantly deviates from a Maxwellian under these conditions. Our work has been motivated, in part, by recent suggestions that highly accurate data for transport coefficients required as input in fluid models of Hg vapor lamp discharges may significantly improve the existing models. Current models of such lamps require a knowledge of the plasma electrical conductivity, which can be calculated from the cross sections for electron scattering in Hg vapor and mobility coefficients presented in this work. The effect of metastable atoms on the swarm parameters is also discussed. The influence of a magnetic field on electron transport coefficients in Hg vapor is investigated over a range of B/N values and angles between the fields.
A Graphical Interpretation of Probit Coefficients.
ERIC Educational Resources Information Center
Becker, William E.; Waldman, Donald M.
1989-01-01
Contends that, when discrete choice models are taught, particularly the probit model, it is the method rather than the interpretation of the results that is emphasized. This article provides a graphical technique for interpretation of an estimated probit coefficient that will be useful in statistics and econometrics courses. (GG)
Oxygen atom loss coefficient of carbon nanowalls
NASA Astrophysics Data System (ADS)
Mozetic, Miran; Vesel, Alenka; Stoica, Silviu Daniel; Vizireanu, Sorin; Dinescu, Gheorghe; Zaplotnik, Rok
2015-04-01
Extremely high values of atomic oxygen loss coefficient on carbon nanowall (CNW) surface are reported. CNW layers consisting of interconnected individual nanostructures with average length of 1.1 μm, average thickness of 66 nm and surface density of 3 CNW/μm2 were prepared by plasma jet enhanced chemical-vapor deposition using C2H2/H2/Ar gas mixtures. The samples were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectrometry (RS) as well as X-ray photoelectron spectroscopy (XPS). The surface loss coefficient was measured at room temperature in a flowing afterglow at different densities of oxygen atoms supplied from inductively coupled radiofrequency O2 plasma. The RF generator operated at 13.56 MHz and different nominal powers up to 900 W corresponding to different O-atom density in the afterglow up to 1.3 × 1021 m-3. CNW and several different samples of known coefficients for heterogeneous surface recombination of neutral oxygen atoms have been placed separately in the afterglow chamber and the O-atom density in their vicinity was measured with calibrated catalytic probes. Comparison of measured results allowed for determination of the loss coefficient for CNWs and the obtained value of 0.59 ± 0.03 makes this material an extremely effective sink for O-atoms.
Phosphorus Availability Coefficients from Various Organic Sources
Technology Transfer Automated Retrieval System (TEKTRAN)
The objectives of this study were to determine Phosphorus Availability Coefficients (PACs) for a variety of organic phosphorus (P) sources, and to examine the relationship between PACs measured in simulated rainfall runoff and alternative soil incubations. PAC is an important parameter in the P-Ind...
Pressure-viscosity coefficient of biobased lubricants
Technology Transfer Automated Retrieval System (TEKTRAN)
Film thickness is an important tribological property that is dependent on the combined effect of lubricant properties, material property of friction surfaces, and the operating conditions of the tribological process. Pressure-viscosity coefficient (PVC) is one of the lubricant properties that influe...
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)
A Primer on Partial Correlation Coefficients.
ERIC Educational Resources Information Center
Waliczek, Tina M.
Part and partial correlation coefficients are used to measure the strength of a relationship between a dependent variable and an independent variable while controlling for one or more other variables. The present paper discusses the uses and limitations of partial correlations and presents a small heuristic data set to illustrate the discussion.…
Pressure viscosity coefficient of vegetable oils
Technology Transfer Automated Retrieval System (TEKTRAN)
The elastohydrodynamic (EHD) pressure viscosity coefficient (PVC) of ten vegetable oils from commodity and new crops, and two petroleum-based oils, polyalphaolefin (PAO) and hexadecane, were investigated. PVC was measured using three different methods: the So and Klaus (S-K) procedure from oil visco...
The Seebeck coefficient of superionic conductors
Mahan, G. D.
2015-01-28
We present a theory of the anomalous Seebeck coefficient found in the superionic conductor Cu{sub 2}Se. It has a phase transition at T = 400 K where the cations disorder but the anions do not. This disorder gives a temperature-dependent width to the electronic states in the conduction band. This width provides the anomalous Seebeck contribution.
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…
EXAMINATION OF SCALE-DEPENDENT DISPERSION COEFFICIENTS
Many hydrologists have observed that dispersion coefficients, when measured in the field, turn out to be scale-dependent. Recently, Guven, et al., (1983) presented a study which contains a basis for understanding the phenomenon of scale-dependent dispersion within a deterministic...
The Evolution of Pearson's Correlation Coefficient
ERIC Educational Resources Information Center
Kader, Gary D.; Franklin, Christine A.
2008-01-01
This article describes an activity for developing the notion of association between two quantitative variables. By exploring a collection of scatter plots, the authors propose a nonstandard "intuitive" measure of association; and by examining properties of this measure, they develop the more standard measure, Pearson's Correlation Coefficient. The…
Molecular Diffusion Coefficients: Experimental Determination and Demonstration.
ERIC Educational Resources Information Center
Fate, Gwendolyn; Lynn, David G.
1990-01-01
Presented are laboratory methods which allow the demonstration and determination of the diffusion coefficients of compounds ranging in size from water to small proteins. Included are the procedures involving the use of a spectrometer, UV cell, triterated agar, and oxygen diffusion. Results including quantification are described. (CW)
Measuring correlations between non-stationary series with DCCA coefficient
NASA Astrophysics Data System (ADS)
Kristoufek, Ladislav
2014-05-01
In this short report, we investigate the ability of the DCCA coefficient to measure correlation level between non-stationary series. Based on a wide Monte Carlo simulation study, we show that the DCCA coefficient can estimate the correlation coefficient accurately regardless the strength of non-stationarity (measured by the fractional differencing parameter d). For a comparison, we also report the results for the standard Pearson correlation coefficient. The DCCA coefficient dominates the Pearson coefficient for non-stationary series.
Activity coefficient of aqueous sodium bicarbonate
Pitzer, Kenneth S.; Peiper, J. Christopher
1980-09-01
The determination of the activity coefficient and related properties of sodium bicarbonate presents special problems because of the appreciable vapor pressure of CO_{2} above such solutions. With the development of reliable equations for the thermodynamic properties of mixed electrolytes, it is possible to determine the parameters for NaHCO_{3} from cell measurements or NaCl-NaHCO_{3} mixtures. Literature data are analyzed to illustrate the method and provide interim values, hoever it is noted that further measurements over a wider range of concentrations would yield more definitive results. Lastly, an estimate is also given for the activity coefficient of KHCO_{3}.
Rotational dissipation and the Miesowicz coefficients.
Simões, M; Yamaguti, K; Palangana, A J
2009-12-01
In this work, we will study the relative contribution of each of the two dissipative channels of the Eriksen, Leslie, and Parodi (ELP) approach to the observed values of the Miesowicz viscosity coefficients of the nematic liquid crystals. According to the fundamental equation of the liquid crystal's viscosity dissipative process, TS=-integral d3r(sigma)ijA(ij)+hxN , there are two channels by which the nematic viscous dissipation can occur: or it occurs by means of a shear flow configuration, where A(ij) is the characterizing term, or it occurs by means of a rotational configuration, where N is the characterizing term (these parameters will be defined in the paper). It will be also shown that this relative contribution can be measured by a simple relationship connecting the Miesowicz coefficients, which exhibits a quasitemperature independent behavior, suggesting that it is nearly constant through the entire domain of the nematic phase. PMID:20365179
Partition coefficients of three new anticonvulsants.
Hernandez-Gallegos, Z; Lehmann, P A
1990-11-01
The partition coefficients of three homologous anticonvulsant phenylalkylamides [racemic alpha-hydroxy-alpha-ethyl-alpha-phenylacetamide (HEPA); beta-hydroxy-beta-ethyl-beta-phenylpropionamide (HEPP); and gamma-hydroxy-gamma-ethyl-gamma-phenylbutyramide (HEPB)] were determined by reversed-phase high-performance liquid chromatography (RP-HPLC). The system was calibrated with a series of simple amines and amides, using their published log P values. The log kw values (methanol:water, extrapolated to 100% water) were 1.260 for HEPA, 1.670 for HEPP, and 1.852 for HEPB. From these results, the partition coefficients (log P) were calculated by regression as 1.20, 1.83, and 2.11, respectively. The log P values were essentially equal to those calculated by the Leo-Hansch fragmental method. Since the potency of the three anticonvulsants is approximately the same in a variety of tests, no dependence on lipophilicity could be established. PMID:2292764
Solute concentration effect on osmotic reflection coefficient.
Adamski, R P; Anderson, J L
1983-01-01
A theory for the effect of concentration on osmotic reflection coefficient, correct to first order, was developed at the molecular level by considering the effect of solute-solute interactions on solute concentration and the fluid stress tensor within a solvent-filled pore. The solvent was modeled as a continuous fluid and potential energies between solute molecules and the pore wall were assumed to be pairwise additive. Although the theory is more general, calculations are presented only for excluded volume effects (hard-sphere for solute, hard-wall for pore). The relationship between the first-order concentration effect and the infinite dilution value of reflection coefficient appears to be geometry independent. The theory is discussed in light of experimental studies of osmotic flow that have recently appeared in the literature. PMID:6626681
Minior Actinide Doppler Coefficient Measurement Assessment
Nolan E. Hertel; Dwayne Blaylock
2008-04-10
The "Minor Actinide Doppler Coefficient Measurement Assessment" was a Department of Energy (DOE) U-NERI funded project intended to assess the viability of using either the FLATTOP or the COMET critical assembly to measure high temperature Doppler coefficients. The goal of the project was to calculate using the MCNP5 code the gram amounts of Np-237, Pu-238, Pu-239, Pu-241, AM-241, AM-242m, Am-243, and CM-244 needed to produce a 1E-5 in reactivity for a change in operating temperature 800C to 1000C. After determining the viability of using the assemblies and calculating the amounts of each actinide an experiment will be designed to verify the calculated results. The calculations and any doncuted experiments are designed to support the Advanced Fuel Cycle Initiative in conducting safety analysis of advanced fast reactor or acceoerator-driven transmutation systems with fuel containing high minor actinide content.
Thermoelectric and Seebeck coefficients of granular metals.
Glatz, A.; Beloborodov, I. S.; Materials Science Division; California State Univ.
2009-01-01
In this work we present a detailed study and derivation of the thermopower and thermoelectric coefficient of nanogranular metals at large tunneling conductance between the grains, g{sub T} >> 1. An important criterion for the performance of a thermoelectric device is the thermodynamic figure of merit which is derived using the kinetic coefficients of granular metals. All results are valid at intermediate temperatures, E{sub c} >> T/g{sub T} > {delta}, where {delta} is the mean energy-level spacing for a single grain and E{sub c} is its charging energy. We show that the electron-electron interaction leads to an increase in the thermopower with decreasing grain size and discuss our results in light of future generation thermoelectric materials for low-temperature applications. The behavior of the figure of merit depending on system parameters such as grain size, tunneling conductance, and temperature is presented.
Correlation and prediction of gaseous diffusion coefficients.
NASA Technical Reports Server (NTRS)
Marrero, T. R.; Mason, E. A.
1973-01-01
A new correlation method for binary gaseous diffusion coefficients from very low temperatures to 10,000 K is proposed based on an extended principle of corresponding states, and having greater range and accuracy than previous correlations. There are two correlation parameters that are related to other physical quantities and that are predictable in the absence of diffusion measurements. Quantum effects and composition dependence are included, but high-pressure effects are not. The results are directly applicable to multicomponent mixtures.
The electron diffusion coefficient in Jupiter's magnetosphere
NASA Technical Reports Server (NTRS)
Birmingham, T.; Northrop, T.; Baxter, R.; Hess, W.; Lojko, M.
1974-01-01
A steady-state model of Jupiter's electron radiation belt is developed. The model includes injection from the solar wind, radial diffusion, energy degradation by synchrotron radiation, and absorption at Jupiter's surface. A diffusion coefficient of the form D sub RR/R sub J squared = k times R to the m-th power is assumed, and then observed data on synchrotron radiation are used to fit the model. The free parameters determined from this fit are m = 1.95 plus or minus 0.5, k = 1.7 plus or minus 0.5 x 10 to the 9th power per sec, and the magnetic moment of injected particles equals 770 plus or minus 300 MeV/G. The value of m shows quite clearly that the diffusion is not caused by magnetic pumping by a variable solar wind or by a fluctuating convection electric field. The process might be field line exchange driven by atmospheric-ionospheric winds; our diffusion coefficient has roughly the same radial dependence but is considerably smaller in magnitude than the upper bound diffusion coefficients recently suggested for this process by Brice and McDonough (1973) and Jacques and Davis (1972).
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.
Field verification of the wind tunnel coefficients
NASA Technical Reports Server (NTRS)
Gawronski, W. K.; Mellstrom, J. A.
1994-01-01
Accurate information about wind action on antennas is required for reliable prediction of antenna pointing errors in windy weather and for the design of an antenna controller with wind disturbance rejection properties. The wind tunnel data obtained 3 years ago using a scaled antenna model serves as an antenna industry standard, frequently used for the first purpose. The accuracy of the wind tunnel data has often been challenged, since they have not yet been tested in a field environment (full-aized antenna, real wind, actual terrain, etc.). The purpose of this investigation was to obtain selected field measurements and compare them with the available wind tunnel data. For this purpose, wind steady-state torques of the DSS-13 antenna were measured, and dimensionless wind torque coefficients were obtained for a variety of yaw and elevation angles. The results showed that the differences between the wind tunnel torque coefficients and the field torque coefficients were less than 10 percent of their values. The wind-gusting action on the antenna was characterized by the power spectra of the antenna encoder and the antenna torques. The spectra showed that wind gusting primarily affects the antenna principal modes.
Discharge Coefficients for Axisymmetric Supersonic Nozzles
NASA Technical Reports Server (NTRS)
Ahmad, Rashid A.; McCool, A. A. (Technical Monitor)
2000-01-01
Computational Fluid Dynamics (CFD) analysis was used to compute effective nozzle discharge coefficients for subscale sharp-edged converging/diverging nozzles, with a variety of convergence half-angles, motor operating conditions, and two propellants with different ballistics. Convergence half-angles ranged from 0 to 80 deg. Analysis was conducted at total temperatures from 2946K (5303R) to 3346K (6023R) and over total pressures ranged from 2.72 MPa (395 psia) to 20.68 MPa (3000 psia). Area ratios (A(sub e)/A*) ranged from 7.43 to 9.39. Ratio of specific heats (gamma) ranged from 1.13 to 1.18. Throat and exit Reynolds numbers were calculated to be 8.26 x 10(exp 5) and 5.51 x 10(exp 5), respectively. Present results of nozzle discharge coefficients are reported and correlated as a function of nozzle convergence half-angle (theta(sub c)) and area ratios (A(sub e)/A*) for a constant divergence half-angle (theta(sub d)) of 15 deg. Computed discharge coefficients ranged from 0.88 to 0.97. They are compared with theory and experimental data available in literature. Available turbulence models with respect to grid refinements and heat transfer are discussed.
Drag coefficients for winter Antarctic pack ice
NASA Technical Reports Server (NTRS)
Wamser, Christian; Martinson, Douglas G.
1993-01-01
Air-ice and ice-water drag coefficients referenced to 10-m-height winds for winter Antarctic pack ice based on measurements made from R/V Polarstern during the Winter Weddell Sea Project, 1986 (WWSP-86), and from R/V Akademik Fedorov during the Winter Weddell Gyre Study, 1989 (WWGS-89), are presented. The optimal values of the air-ice drag coefficients, made from turbulent flux measurements, are (1.79 +/- 0.06) x 10 exp -3 for WWSP-86 and (1.45 +/- 0.09) x 10 exp -3 for WWGS-89. A single ice-water drag coefficient for both WWSP-86 and WWGS-89, estimated from periods of ice drift throught to represent free-drift conditions, is (1.13 +/- 0.26) x 10 exp -3, and the ice-water turning angle is 18 +/- 18 deg. It is suggested that for a typical Antarctic winter pack ice cover, the ice cover reduces the momentum flux from the atmosphere to the ocean by about 33 percent.
NASA Astrophysics Data System (ADS)
Sergievskii, V. V.; Rudakov, A. M.
2016-08-01
The model that considers the nonideality of aqueous solutions of electrolytes with allowance for independent contributions of hydration of ions of various types and electrostatic interactions was substantiated using the cluster ion model. The empirical parameters in the model equations were found to be the hydrophilic and hydrophobic hydration numbers of ions in the standard state and the dispersion of their distribution over the stoichiometric coefficients. A mathematically adequate description of the concentration dependences of the osmotic coefficients and average ion activity coefficients of electrolytes was given for several systems. The difference in the rate of the decrease in the hydrophilic and hydrophobic hydration numbers of ions leads to extremum concentration dependences of the osmotic coefficients, which were determined by other authors from isopiestic data for many electrolytes and did not find explanation.
Third Order Elastic Coefficients of Rocks
NASA Astrophysics Data System (ADS)
Bandyopadhyay, K.
2006-12-01
We present a methodology to determine third order elastic (TOE) coefficients of rock from velocity measurements at different hydrostatic stress level. TOE coefficients help us to obtain a quantitative measure of the variation of velocity with stress. It is one of the most general ways to parameterize the stress sensitivity of rocks. We usually determine the isotropic TOE coefficients from measurements of all the independent stiffness elements under non-hydrostatic stress. However, for initially isotropic or weakly anisotropic rocks, most of the laboratory experiments are carried out under hydrostatic stress. In that case, the measurements of P- and S-wave velocities at different hydrostatic pressure alone are not enough to invert for the isotropic TOE parameters. In this underdetermined situation, more information about the rock microstructure causing the non-linearity is required to predict seismic velocities at any arbitrary stress state. Our workflow is based on the model of Mavko et al. (1995) to compute stress-induced anisotropy. This model assumes that the cause of elastic nonlinearity is the presence of compliant crack-like pore. The pressure dependence of generalized compliances is mainly governed by normal tractions resolved across cracks. This assumption allows one to map the pressure dependence from hydrostatic stress to any state of stress. Applying the model of Mavko et al. (1995), we obtain the full stiffness tensor at different non-hydrostatic stress levels from the usual Vp and Vs measurements. Changes in elastic stiffness elements from a reference state of stress are then used to invert for the TOE coefficients, C111, C112 and C123 using the third order stress- strain relations. This method allows us to compute the TOE elements using hydrostatic measurements of an initially isotropic rock. We show an application of the workflow with laboratory measurements of P- and S-wave velocities under varying hydrostatic stress. This enables us to express
A Computer for Calculating Kendall's Rank Correlation Coefficients
ERIC Educational Resources Information Center
Roberge, James J.
1970-01-01
A program for calculating Kendall's tau-a, tau-b, partial tau, coefficient of concordance, coefficient of consistence, and coefficient of agreement is presented. In addition, the program provides tests of significance for each of the coefficients except partial tau. (DG)
Inversion of instantaneous equivalent absorption coefficient and its application
Weihua, W. )
1992-01-01
Absorption coefficient is an important parameter for reservoir description. The major troubles in extracting absorption coefficient from seismic data are amplitude and waveform distortions; they greatly restrict the inversion which is based on reflection amplitude variation or reflection frequency variation. This paper presents a new method which avoids amplitude and uses waveform variation gradient in wave propagation to make the inversion of absorption coefficient. Apparent absorption coefficient and pseudo absorption coefficient are adopted so as to remove the influence which the waveform distortion due to thin bed tuning brings to absorption coefficient extraction. The final instantaneous equivalent absorption coefficient, a true absorption coefficient which reflects real absorptive character of a seismic medium, can be obtained by subtracting the pseudo absorption coefficient (inversely calculated using maximum entropy) from the apparent absorption coefficient the authors have calculated.
Direct Measurements of the Pressure Coefficient, Partial
NASA Astrophysics Data System (ADS)
del Cueto, Joseph Antonio
1984-06-01
The pressure coefficient of liquid ('3)He-('4)He mixtures was coupled to directly, with a strain gauge capacitative cell. The cell was filled, pressurized and isolated with a mixture, of ('3)He mole fraction x between 0.50-0.80. The elastic properties of the cell effected a capacitance change in an LC tank circuit driven to oscillation by a Tunnel Diode. The frequency of the circuit, as well as the balance point of an AC Wheatstone circuit sensing a cryo-resistor mounted on the cell, were sampled by a data acquisition(DAS) system, to obtain pressure vs. temperature increments data. The DAS was enabled to perform temperature ramps and cycles with amplitudes of (TURN) (+OR-) 50-100 mK, while concurrently sampling pressure vs. temperature data. It is found that (PAR-DIFF)P/(PAR-DIFF)T)(,v,x) is a piecewise smooth function in the temperature T. For x < x(,t)(P), the data indicate a cusp discontinuity at the lambda temperature of the mixture T(,(lamda))(x,v(p(,(lamda)))), and a simple discontinuity at the onset of phase separation temperature T(,S)(x,v(p(,S))). For x > x(,t)(P), only the phase separation breaks the monotonic behaviour of the pressure coefficient. Where x(,t)(P) is the tricritical concentration at pressure P, referred to in the above. The data for the pressure coefficients are parametrized by smooth functions in appendix 5. This parametrization allows for further thermodynamic analysis, as that of appendix 6, the change in chemical potential difference upon compression. The thermodynamic implications of the measured step in (PAR -DIFF)P/(PAR-DIFF)T)(,v,x), across the onset separation temperature, are explored in appendix 4. The 'volume' minima at the pressures the isochores cross at their pressure minima in temperature, are plotted and analysed to imply that for some concentrations x, the entropy of the mixture is a double valued function of absolute pressure.
Transport coefficients of He(+) ions in helium.
Viehland, Larry A; Johnsen, Rainer; Gray, Benjamin R; Wright, Timothy G
2016-02-21
This paper demonstrates that the transport coefficients of (4)He(+) in (4)He can be calculated over wide ranges of E/N, the ratio of the electrostatic field strength to the gas number density, with the same level of precision as can be obtained experimentally if sufficiently accurate potential energy curves are available for the X(2)Σu (+) and A(2)Σg (+) states and one takes into account resonant charge transfer. We start by computing new potential energy curves for these states and testing their accuracy by calculating spectroscopic values for the separate states. It is established that the potentials obtained by extrapolation of results from d-aug-cc-pVXZ (X = 6, 7) basis sets using the CASSCF+MRCISD approach are each in exceptionally close agreement with the best potentials available and with experiment. The potentials are then used in a new computer program to determine the semi-classical phase shifts and the transport cross sections, and from these the gaseous ion transport coefficients are determined. In addition, new experimental values are reported for the mobilities of (4)He(+) in (4)He at 298.7 K, as a function of E/N, where careful consideration is given to minimizing various sources of uncertainty. Comparison with previously measured values establishes that only one set of previous data is reliable. Finally, the experimental and theoretical ion transport coefficients are shown to be in very good to excellent agreement, once corrections are applied to account for quantum-mechanical effects. PMID:26896985
Transport coefficients of He+ ions in helium
NASA Astrophysics Data System (ADS)
Viehland, Larry A.; Johnsen, Rainer; Gray, Benjamin R.; Wright, Timothy G.
2016-02-01
This paper demonstrates that the transport coefficients of 4He+ in 4He can be calculated over wide ranges of E/N, the ratio of the electrostatic field strength to the gas number density, with the same level of precision as can be obtained experimentally if sufficiently accurate potential energy curves are available for the X2Σu+ and A2Σg+ states and one takes into account resonant charge transfer. We start by computing new potential energy curves for these states and testing their accuracy by calculating spectroscopic values for the separate states. It is established that the potentials obtained by extrapolation of results from d-aug-cc-pVXZ (X = 6, 7) basis sets using the CASSCF+MRCISD approach are each in exceptionally close agreement with the best potentials available and with experiment. The potentials are then used in a new computer program to determine the semi-classical phase shifts and the transport cross sections, and from these the gaseous ion transport coefficients are determined. In addition, new experimental values are reported for the mobilities of 4He+ in 4He at 298.7 K, as a function of E/N, where careful consideration is given to minimizing various sources of uncertainty. Comparison with previously measured values establishes that only one set of previous data is reliable. Finally, the experimental and theoretical ion transport coefficients are shown to be in very good to excellent agreement, once corrections are applied to account for quantum-mechanical effects.
Experimental rotordynamic coefficient results for honeycomb seals
NASA Technical Reports Server (NTRS)
Elrod, David A.; Childs, Dara W.
1988-01-01
Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.
Optical loss coefficient in plastic waveguides
NASA Astrophysics Data System (ADS)
Geetha, K.; Gopinath, Pramod; Unnikrishnan, K. P.; Lee, S. T.; Vallabhan, C. P. G.; Nampoori, V. P. N.; Radhakrishnan, Periasamy
2002-09-01
We report the position dependent tuning of fluorescence emission from Rhodamine 6G doped plastic waveguide using side illumination technique . The transmitted fluorescence as a function of the distance from the point of illumination is measured by translating the waveguide horizontally across a monochromatic light source. This technique has proved to be a useful method for characterizing the light propagation properties of dye-doped waveguides. An important finding of the present studies is the nonlinear behavior of the loss coefficient as a function of propagation distance through the waveguide. It is also found that this type of nonlinear nature depends on the dye concentration and thickness of the waveguide.
Elastic-Stiffness Coefficients of Titanium Diboride
Ledbetter, Hassel; Tanaka, Takaho
2009-01-01
Using resonance ultrasound spectroscopy, we measured the monocrystal elastic-stiffness coefficients, the Voigt Cij, of TiB2. With hexagonal symmetry, TiB2 exhibits five independent Cij: C11, C33, C44, C12, C13. Using Voigt-Reuss-Hill averaging, we converted these monocrystal values to quasiisotropic (polycrystal) elastic stiffnesses. Briefly, we comment on effects of voids. From the Cij, we calculated the Debye characteristic temperature, the Grüneisen parameter, and various sound velocities. Our study resolves the enormous differences between two previous reports of TiB2’s Cij.
Bounds on Transport Coefficients of Porous Media
Berryman, J G
2005-03-21
An analytical formulation of conductivity bounds by Bergman and Milton is used in a different way to obtain rigorous bounds on the real transport coefficients (electrical conductivity, thermal conductivity, and/or fluid permeability) of a fluid-saturated porous medium. These bounds do not depend explicitly on the porosity, but rather on two formation factors--one associated with the pore space and the other with the solid frame. Hashin-Shtrikman bounds for transport in random polycrystals of porous-material laminates will also be discussed.
Studies of Gaseous Multiplication Coefficient in Isobutane
Lima, Iara B.; Vivaldini, Tulio C.; Goncalves, Josemary A. C.; Botelho, Suzana; Bueno Tobias, Carmen C.; Ridenti, Marco A.; Pascholati, Paulo R.; Fonte, Paulo; Mangiarotti, Alessio
2010-05-21
This work presents the studies of gaseous multiplication coefficient behavior for isobutane, as function of the reduced electric field, by means of signal amplitude analysis. The experimental method used is based on the Pulsed Townsend technique, which follows from Townsend equation solution for a uniform electric field. In our configuration, the anode is made of a high resistivity (2.10{sup 12} OMEGA.cm) glass, while the cathode is of aluminium. In order to validate the technique and to analyze effects of non-uniformity, results for nitrogen, which has well-established data available in literature, are also presented.
Modeling canopy reflectance and microwave backscattering coefficient
NASA Technical Reports Server (NTRS)
Goel, N. S.
1985-01-01
Various approaches to model canopy reflectance (CR) in the visible/infrared region and backscattering coefficient (BSC) in the microwave region are compared and contrasted. It is noted that BSC can be related to CR in the source direction (the 'hot spot' direction). By assuming a frequency dependent leaf reflectance and transmittance it is shown that the observed dependence of BSC on leaf area index, leaf angle distribution, angle of incidence, soil moisture content, and frequency can be simulated by a CR model. Thus both BSC and CR can, in principle, be calculated using a single model which has essentially the same parameters as many CR models do.
Micro-Fluidic Diffusion Coefficient Measurement
Forster, F.K.; Galambos, P.
1998-10-06
A new method for diffusion coefficient measurement applicable to micro-fluidics is pre- sented. The method Iltilizes an analytical model describing laminar dispersion in rect- anglllar ~llicro_channe]s. The Illethod ~vas verified throllgh measllremen~ of fllloresceill diffusivity in water and aqueolls polymer solutions of differing concentration. The diffll- sivity of flllorescein was measlmed as 0.64 x 10-gm2/s in water, 0.49 x 10-gm2/s in the 4 gm/dl dextran solution and 0.38 x 10-9n12/s in the 8 gnl/dl dextran solution.
Surface area coefficients for airship envelopes
NASA Technical Reports Server (NTRS)
Diehl, W S
1922-01-01
In naval architecture, it is customary to determine the wetted surface of a ship by means of some formula which involves the principal dimensions of the design and suitable constants. These formulas of naval architecture may be extended and applied to the calculation of the surface area of airship envelopes by the use of new values of the constants determined for this purpose. Surface area coefficients were calculated from the actual dimensions, surfaces, and volumes of 52 streamline bodies, which form a series covering the entire range of shapes used in the present aeronautical practice.
Studies of Gaseous Multiplication Coefficient in Isobutane
NASA Astrophysics Data System (ADS)
Lima, Iara B.; Vivaldini, Túlio C.; Gonçalves, Josemary A. C.; Botelho, Suzana; Ridenti, Marco A.; Fonte, Paulo; Mangiarotti, Alessio; Pascholati, Paulo R.; Bueno Tobias, Carmen C.
2010-05-01
This work presents the studies of gaseous multiplication coefficient behavior for isobutane, as function of the reduced electric field, by means of signal amplitude analysis. The experimental method used is based on the Pulsed Townsend technique, which follows from Townsend equation solution for a uniform electric field. In our configuration, the anode is made of a high resistivity (2.1012 Ω.cm) glass, while the cathode is of aluminium. In order to validate the technique and to analyze effects of non-uniformity, results for nitrogen, which has well-established data available in literature, are also presented.
Reactive sticking coefficients of silane on silicon
Buss, R.J.; Ho, P.; Breiland, W.G.; Coltrin, M.E.
1988-09-15
Reactive sticking coefficients (RSCs) were measured for silane and disilane on polycrystalline silicon for a wide range of temperature and flux (pressure) conditions. The data were obtained from deposition rate measurements using molecular beam scattering and a very low pressure cold wall reactor. The RSCs have non-Arrhenius temperature dependences and decreases with increasing flux at low (710/sup 0/) temperatures. A simple model involving dissociative adsorption of silane is consistent with these results. The results are compared with previous studies of the SiH/sub 4//Si(s) reaction.
Hu, Shasa; Sherman, Recinda; Arheart, Kristopher; Kirsner, Robert S
2014-04-01
Minority populations have disproportionately more advanced stage melanoma and worse survival. To clarify the impact of race and ethnicity on late-stage melanoma diagnosis, we performed spatial analysis of geocoded melanoma cases diagnosed in Florida, 1999-2008, to identify geographic clusters of higher-than-expected incidence of late-stage melanoma and developed predictive models for melanoma cases in high-risk neighborhoods accounting for area-based poverty, race/ethnicity, patient insurance status, age, and gender. In the adjusted model, Hispanic ethnicity and census tract-level poverty are the strongest predictors for clustering of late-stage melanoma. Hispanic whites were 43% more likely to live in neighborhoods with excessive late-stage melanoma (P<0.001) compared with non-Hispanic whites (NHW). For every 1% increase in population living in poverty, there is a 2% increase in late-stage melanoma clustering (P<0.001). Census tract-level poverty predicted late-stage melanoma similarly among NHW and Hispanic whites. The impact of insurance coverage varied among populations; the most consistent trend was that Medicaid coverage is associated with higher odds for late-stage melanoma. The finding that Hispanics are most likely to reside in high-risk neighborhoods, independent of poverty and insurance status, underscores the importance of addressing, and overcoming community-level barriers to melanoma care. PMID:24335896
NASA Astrophysics Data System (ADS)
El Khrepy, Sami; Koulakov, Ivan; Al-Arifi, Nassir; Petrunin, Alexey G.
2016-06-01
We present the first 3-D model of seismic P and S velocities in the crust and uppermost mantle beneath the Gulf of Aqaba and surrounding areas based on the results of passive travel time tomography. The tomographic inversion was performed based on travel time data from ˜ 9000 regional earthquakes provided by the Egyptian National Seismological Network (ENSN), and this was complemented with data from the International Seismological Centre (ISC). The resulting P and S velocity patterns were generally consistent with each other at all depths. Beneath the northern part of the Red Sea, we observed a strong high-velocity anomaly with abrupt limits that coincide with the coastal lines. This finding may indicate the oceanic nature of the crust in the Red Sea, and it does not support the concept of gradual stretching of the continental crust. According to our results, in the middle and lower crust, the seismic anomalies beneath the Gulf of Aqaba seem to delineate a sinistral shift (˜ 100 km) in the opposite flanks of the fault zone, which is consistent with other estimates of the left-lateral displacement in the southern part of the Dead Sea Transform fault. However, no displacement structures were visible in the uppermost lithospheric mantle.
Hierarchical coefficient of a multifractal based network
NASA Astrophysics Data System (ADS)
Moreira, Darlan A.; Lucena, Liacir dos Santos; Corso, Gilberto
2014-02-01
The hierarchical property for a general class of networks stands for a power-law relation between clustering coefficient, CC and connectivity k: CC∝kβ. This relation is empirically verified in several biologic and social networks, as well as in random and deterministic network models, in special for hierarchical networks. In this work we show that the hierarchical property is also present in a Lucena network. To create a Lucena network we use the dual of a multifractal lattice ML, the vertices are the sites of the ML and links are established between neighbouring lattices, therefore this network is space filling and planar. Besides a Lucena network shows a scale-free distribution of connectivity. We deduce a relation for the maximal local clustering coefficient CCimax of a vertex i in a planar graph. This condition expresses that the number of links among neighbour, N△, of a vertex i is equal to its connectivity ki, that means: N△=ki. The Lucena network fulfils the condition N△≃ki independent of ki and the anisotropy of ML. In addition, CCmax implies the threshold β=1 for the hierarchical property for any scale-free planar network.
The Convergence Coefficient across Political Systems
Schofield, Norman
2013-01-01
Formal work on the electoral model often suggests that parties or candidates should locate themselves at the electoral mean. Recent research has found no evidence of such convergence. In order to explain nonconvergence, the stochastic electoral model is extended by including estimates of electoral valence. We introduce the notion of a convergence coefficient, c. It has been shown that high values of c imply that there is a significant centrifugal tendency acting on parties. We used electoral surveys to construct a stochastic valence model of the the elections in various countries. We find that the convergence coefficient varies across elections in a country, across countries with similar regimes, and across political regimes. In some countries, the centripetal tendency leads parties to converge to the electoral mean. In others the centrifugal tendency dominates and some parties locate far from the electoral mean. In particular, for countries with proportional electoral systems, namely, Israel, Turkey, and Poland, the centrifugal tendency is very high. In the majoritarian polities of the United States and Great Britain, the centrifugal tendency is very low. In anocracies, the autocrat imposes limitations on how far from the origin the opposition parties can move. PMID:24385886
Estimating biokinetic coefficients in the PACT™ system.
Shen, Zhiyao; Arbuckle, Wm Brian
2016-02-01
When powdered activated carbon (PAC) is continuously added to the aeration tank of an activated sludge reactor, the modification is called a PACT™ process (for powdered activated carbon treatment). The PAC provides many benefits, but complicates the determination of biological phenomena. Determination of bio-oxidation kinetics in a PACT system is a key to fully understanding enhanced biological mechanisms resulting from PAC addition. A model is developed to account for the main mechanisms involved in the PACT system -- adsorption, air stripping and bio-oxidation. The model enables the investigation of biokinetic information, including possible synergistic effects. Six parallel reactors were used to treat a synthetic waste; three activated sludge and three PACT. The PACT reactors provided significantly reduced effluent TOC (total organic carbon). Biokinetic coefficients were obtained from steady-state data using averaged reactor data and by using all data (22 points for each reactor). As expected, the PACT reactors resulted in a substantial reduction in the effluent concentration of non-biodegradable total organic carbon. The Monod equation's half-saturation coefficient (Ks) was reduced significantly in the PACT reactors, resulting in higher growth rates at lower concentrations. The maximum specific substrate utilization (qm) rate was also reduced about 25% using the averaged data and remained unchanged using all the data. The substrate utilization values are affected by errors in biomass determination and more research is needed to accurately determine biomass. PMID:26613352
Rotordynamic coefficients for stepped labyrinth gas seals
NASA Technical Reports Server (NTRS)
Scharrer, Joseph K.
1989-01-01
The basic equations are derived for compressible flow in a stepped labyrinth gas seal. The flow is assumed to be completely turbulent in the circumferential direction where the friction factor is determined by the Blasius relation. Linearized zeroth and first-order perturbation equations are developed for small motion about a centered position by an expansion in the eccentricity ratio. The zeroth-order pressure distribution is found by satisfying the leakage equation while the circumferential velocity distribution is determined by satisfying the momentum equations. The first order equations are solved by a separation of variables solution. Integration of the resultant pressure distribution along and around the seal defines the reaction force developed by the seal and the corresponding dynamic coefficients. The results of this analysis are presented in the form of a parametric study, since there are no known experimental data for the rotordynamic coefficients of stepped labyrinth gas seals. The parametric study investigates the relative rotordynamic stability of convergent, straight and divergent stepped labyrinth gas seals. The results show that, generally, the divergent seal is more stable, rotordynamically, than the straight or convergent seals. The results also show that the teeth-on-stator seals are not always more stable, rotordynamically, then the teeth-on-rotor seals as was shown by experiment by Childs and Scharrer (1986b) for a 15 tooth seal.
Angular Fock coefficients: Refinement and further development
NASA Astrophysics Data System (ADS)
Liverts, Evgeny Z.; Barnea, Nir
2015-10-01
The angular coefficients ψk ,p(α ,θ ) of the Fock expansion characterizing the S -state wave function of the two-electron atomic system are calculated in hyperspherical angular coordinates α and θ . To solve the problem the Fock recurrence relations separated into the independent individual equations associated with definite power j of the nucleus charge Z are applied. The "pure" j components of the angular Fock coefficients, orthogonal to the hyperspherical harmonics Yk l, are found for even values of k . To this end, the specific coupling equation is proposed and applied. Effective techniques for solving the individual equations with the simplest nonseparable and separable right-hand sides are proposed. Some mistakes or misprints made earlier in representations of ψ2 ,0, are noted and corrected. All j components of ψ4 ,1 and the majority of components and subcomponents of ψ3 ,0 are calculated and presented. All calculations are carried out with the help of Wolfram Mathematica.
Coefficient adaptive triangulation for strongly anisotropic problems
D`Azevedo, E.F.; Romine, C.H.; Donato, J.M.
1996-01-01
Second order elliptic partial differential equations arise in many important applications, including flow through porous media, heat conduction, the distribution of electrical or magnetic potential. The prototype is the Laplace problem, which in discrete form produces a coefficient matrix that is relatively easy to solve in a regular domain. However, the presence of anisotropy produces a matrix whose condition number is increased, making the resulting linear system more difficult to solve. In this work, we take the anisotropy into account in the discretization by mapping each anisotropic region into a ``stretched`` coordinate space in which the anisotropy is removed. The region is then uniformly triangulated, and the resulting triangulation mapped back to the original space. The effect is to generate long slender triangles that are oriented in the direction of ``preferred flow.`` Slender triangles are generally regarded as numerically undesirable since they tend to cause poor conditioning; however, our triangulation has the effect of producing effective isotropy, thus improving the condition number of the resulting coefficient matrix.
On Learning Cluster Coefficient of Private Networks
Wang, Yue; Wu, Xintao; Zhu, Jun; Xiang, Yang
2013-01-01
Enabling accurate analysis of social network data while preserving differential privacy has been challenging since graph features such as clustering coefficient or modularity often have high sensitivity, which is different from traditional aggregate functions (e.g., count and sum) on tabular data. In this paper, we treat a graph statistics as a function f and develop a divide and conquer approach to enforce differential privacy. The basic procedure of this approach is to first decompose the target computation f into several less complex unit computations f1, …, fm connected by basic mathematical operations (e.g., addition, subtraction, multiplication, division), then perturb the output of each fi with Laplace noise derived from its own sensitivity value and the distributed privacy threshold εi, and finally combine those perturbed fi as the perturbed output of computation f. We examine how various operations affect the accuracy of complex computations. When unit computations have large global sensitivity values, we enforce the differential privacy by calibrating noise based on the smooth sensitivity, rather than the global sensitivity. By doing this, we achieve the strict differential privacy guarantee with smaller magnitude noise. We illustrate our approach by using clustering coefficient, which is a popular statistics used in social network analysis. Empirical evaluations on five real social networks and various synthetic graphs generated from three random graph models show the developed divide and conquer approach outperforms the direct approach. PMID:24429843
Ionization coefficient measurements in DC microplasmas
NASA Astrophysics Data System (ADS)
Stefanovic, Ilija; Kuschel, Thomas; Winter, Joerg; Maric, Dragana; Petrovic, Zoran Lj.
2012-10-01
While steady state Townsend discharges may provide data for ionization coefficients those are often not as accurate as those produced in dedicated pulsed current growth experiments. In this paper we show that one may be able to measure ionization coefficients in DC microdischarges that are of excellent quality. Measurements were made for argon and argon/nitrogen mixtures with different gas flow rates. The technique based measuring the spatial profile of emission a Townsend discharge. In spite of having the drift length of only 1 mm, excellent agreement has been found between our new measurements and the data for low-pressure, larger dimension (2-4cm) discharges in argon (Jelenak et al) for the E/N in the range from 300 Td to 4000 Td, where E/N is normalized electrical field strength. Below 300 Td our measured values are larger then those by Jelenak et al. This discrepancy with previous measurements will be discussed. The influence of the gas flow-rate and nitrogen concentration on the radial discharge profile in the Townsend mode will also be presented and discussed. Jelenak et al 1993 Phys. Rev. E 47 3566
Link prediction with node clustering coefficient
NASA Astrophysics Data System (ADS)
Wu, Zhihao; Lin, Youfang; Wang, Jing; Gregory, Steve
2016-06-01
Predicting missing links in incomplete complex networks efficiently and accurately is still a challenging problem. The recently proposed Cannistrai-Alanis-Ravai (CAR) index shows the power of local link/triangle information in improving link-prediction accuracy. Inspired by the idea of employing local link/triangle information, we propose a new similarity index with more local structure information. In our method, local link/triangle structure information can be conveyed by clustering coefficient of common-neighbors directly. The reason why clustering coefficient has good effectiveness in estimating the contribution of a common-neighbor is that it employs links existing between neighbors of a common-neighbor and these links have the same structural position with the candidate link to this common-neighbor. In our experiments, three estimators: precision, AUP and AUC are used to evaluate the accuracy of link prediction algorithms. Experimental results on ten tested networks drawn from various fields show that our new index is more effective in predicting missing links than CAR index, especially for networks with low correlation between number of common-neighbors and number of links between common-neighbors.
Xu, Suxin; Chen, Jiangang; Wang, Bijia; Yang, Yiqi
2015-11-15
Two predictive models were presented for the adsorption affinities and diffusion coefficients of disperse dyes in polylactic acid matrix. Quantitative structure-sorption behavior relationship would not only provide insights into sorption process, but also enable rational engineering for desired properties. The thermodynamic and kinetic parameters for three disperse dyes were measured. The predictive model for adsorption affinity was based on two linear relationships derived by interpreting the experimental measurements with molecular structural parameters and compensation effect: ΔH° vs. dye size and ΔS° vs. ΔH°. Similarly, the predictive model for diffusion coefficient was based on two derived linear relationships: activation energy of diffusion vs. dye size and logarithm of pre-exponential factor vs. activation energy of diffusion. The only required parameters for both models are temperature and solvent accessible surface area of the dye molecule. These two predictive models were validated by testing the adsorption and diffusion properties of new disperse dyes. The models offer fairly good predictive ability. The linkage between structural parameter of disperse dyes and sorption behaviors might be generalized and extended to other similar polymer-penetrant systems. PMID:26197108
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.
NASA Astrophysics Data System (ADS)
Vastaranta, Mikko; Kankare, Ville; Holopainen, Markus; Yu, Xiaowei; Hyyppä, Juha; Hyyppä, Hannu
2012-01-01
The two main approaches to deriving forest variables from laser-scanning data are the statistical area-based approach (ABA) and individual tree detection (ITD). With ITD it is feasible to acquire single tree information, as in field measurements. Here, ITD was used for measuring training data for the ABA. In addition to automatic ITD (ITD auto), we tested a combination of ITD auto and visual interpretation (ITD visual). ITD visual had two stages: in the first, ITD auto was carried out and in the second, the results of the ITD auto were visually corrected by interpreting three-dimensional laser point clouds. The field data comprised 509 circular plots ( r = 10 m) that were divided equally for testing and training. ITD-derived forest variables were used for training the ABA and the accuracies of the k-most similar neighbor ( k-MSN) imputations were evaluated and compared with the ABA trained with traditional measurements. The root-mean-squared error (RMSE) in the mean volume was 24.8%, 25.9%, and 27.2% with the ABA trained with field measurements, ITD auto, and ITD visual, respectively. When ITD methods were applied in acquiring training data, the mean volume, basal area, and basal area-weighted mean diameter were underestimated in the ABA by 2.7-9.2%. This project constituted a pilot study for using ITD measurements as training data for the ABA. Further studies are needed to reduce the bias and to determine the accuracy obtained in imputation of species-specific variables. The method could be applied in areas with sparse road networks or when the costs of fieldwork must be minimized.
Fractional diffusions with time-varying coefficients
NASA Astrophysics Data System (ADS)
Garra, Roberto; Orsingher, Enzo; Polito, Federico
2015-09-01
This paper is concerned with the fractionalized diffusion equations governing the law of the fractional Brownian motion BH(t). We obtain solutions of these equations which are probability laws extending that of BH(t). Our analysis is based on McBride fractional operators generalizing the hyper-Bessel operators L and converting their fractional power Lα into Erdélyi-Kober fractional integrals. We study also probabilistic properties of the random variables whose distributions satisfy space-time fractional equations involving Caputo and Riesz fractional derivatives. Some results emerging from the analysis of fractional equations with time-varying coefficients have the form of distributions of time-changed random variables.
Isotope coefficient in high Tc superconductors
Kishore, R.
1995-10-01
An exact expression for the isotope coefficient ({alpha}), within the conventional BCS theory, has been derived for any arbitrary electronic density of states and the mass dependence of carrier concentration. It is shown that the effect of the mass dependence of the carrier concentration within the van-Hove scenario (VHS) can explain some anomalous features of {alpha} for La{sub 2}CuO{sub 4} based superconductors, not explained by earlier theories based on VHS. These anomalous features are the asymmetry of {alpha} about the optimum concentration (n{sub m}) corresponding to the maximum critical temperature, minimum in {alpha} above n{sub m}, and the value of {alpha} less than 0.5 below n{sub m}.
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.
Effective Electrocardiogram Steganography Based on Coefficient Alignment.
Yang, Ching-Yu; Wang, Wen-Fong
2016-03-01
This study presents two types of data hiding methods based on coefficient alignment for electrocardiogram (ECG) signals, namely, lossy and reversible ECG steganographys. The lossy method is divided into high-quality and high-capacity ECG steganography, both of which are capable of hiding confidential patient data in ECG signals. The reversible data hiding method can not only hide secret messages but also completely restore the original ECG signal after bit extraction. Simulations confirmed that the perceived quality generated by the lossy ECG steganography methods was good, while hiding capacity was acceptable. In addition, these methods have a certain degree of robustness, which is rare in conventional ECG stegangraphy schemes. Moreover, the proposed reversible ECG steganography method can not only successfully extract hidden messages but also completely recover the original ECG data. PMID:26711443
Partition Coefficients at High Pressure and Temperature
NASA Astrophysics Data System (ADS)
Righter, K.; Drake, M. J.
2003-12-01
Differentiation of terrestrial planets includes separation of a metallic core and possible later fractionation of mineral phases within either a solid or molten mantle (Figure 1). Lithophile and siderophile elements can be used to understand these two different physical processes, and ascertain whether they operated in the early Earth. The distribution of elements in planets can be understood by measuring the partition coefficient, D (ratio of concentrations of an element in different phases (minerals, metals, or melts)). (14K)Figure 1. Schematic cross-section through the Earth, showing: (a) an early magma ocean stage and (b) a later cool and differentiated stage. The siderophile elements (iron-loving) encompass over 30 elements and are defined as those elements for which D(metal/silicate)>1, and are useful for deciphering the details of core formation. This group of elements is commonly broken up into several subclasses, including the slightly siderophile elements (1
Implicit Extrapolation Methods for Variable Coefficient Problems
NASA Technical Reports Server (NTRS)
Jung, M.; Ruede, U.
1996-01-01
Implicit extrapolation methods for the solution of partial differential equations are based on applying the extrapolation principle indirectly. Multigrid tau-extrapolation is a special case of this idea. In the context of multilevel finite element methods, an algorithm of this type can be used to raise the approximation order, even when the meshes are nonuniform or locally refined. Here previous results are generalized to the variable coefficient case and thus become applicable for nonlinear problems. The implicit extrapolation multigrid algorithm converges to the solution of a higher order finite element system. This is obtained without explicitly constructing higher order stiffness matrices but by applying extrapolation in a natural form within the algorithm. The algorithm requires only a small change of a basic low order multigrid method.
Transport coefficients in superfluid neutron stars
NASA Astrophysics Data System (ADS)
Tolos, Laura; Manuel, Cristina; Sarkar, Sreemoyee; Tarrus, Jaume
2016-01-01
We study the shear and bulk viscosity coefficients as well as the thermal conductivity as arising from the collisions among phonons in superfluid neutron stars. We use effective field theory techniques to extract the allowed phonon collisional processes, written as a function of the equation of state and the gap of the system. The shear viscosity due to phonon scattering is compared to calculations of that coming from electron collisions. We also comment on the possible consequences for r-mode damping in superfluid neutron stars. Moreover, we find that phonon collisions give the leading contribution to the bulk viscosities in the core of the neutron stars. We finally obtain a temperature-independent thermal conductivity from phonon collisions and compare it with the electron-muon thermal conductivity in superfluid neutron stars.
Manning's roughness coefficient for Illinois streams
Soong, David T.; Prater, Crystal D.; Halfar, Teresa M.; Wobig, Loren A.
2012-01-01
Manning's roughness coefficients for 43 natural and constructed streams in Illinois are reported and displayed on a U.S. Geological Survey Web site. At a majority of the sites, discharge and stage were measured, and corresponding Manning's coefficients—the n-values—were determined at more than one river discharge. The n-values discussed in this report are computed from data representing the stream reach studied and, therefore, are reachwise values. Presentation of the resulting n-values takes a visual-comparison approach similar to the previously published Barnes report (1967), in which photographs of channel conditions, description of the site, and the resulting n-values are organized for each site. The Web site where the data can be accessed and are displayed is at URL http://il.water.usgs.gov/proj/nvalues/.
Transport Coefficients in weakly compressible turbulence
NASA Technical Reports Server (NTRS)
Rubinstein, Robert; Erlebacher, Gordon
1996-01-01
A theory of transport coefficients in weakly compressible turbulence is derived by applying Yoshizawa's two-scale direct interaction approximation to the compressible equations of motion linearized about a state of incompressible turbulence. The result is a generalization of the eddy viscosity representation of incompressible turbulence. In addition to the usual incompressible eddy viscosity, the calculation generates eddy diffusivities for entropy and pressure, and an effective bulk viscosity acting on the mean flow. The compressible fluctuations also generate an effective turbulent mean pressure and corrections to the speed of sound. Finally, a prediction unique to Yoshizawa's two-scale approximation is that terms containing gradients of incompressible turbulence quantities also appear in the mean flow equations. The form these terms take is described.
Molar extinction coefficients of some fatty acids
NASA Astrophysics Data System (ADS)
Sandhu, G. K.; Singh, Kulwant; Lark, B. S.; Gerward, L.
2002-10-01
The attenuation of gamma rays in some fatty acids, viz. formic acid (CH 2O 2), acetic acid (C 2H 4O 2), propionic acid (C 3H 6O 2), butyric acid (C 4H 8O 2), n-hexanoic acid (C 6H 12O 2), n-caprylic acid (C 8H 16O 2), lauric acid (C 12H 24O 2), myristic acid (C 14H 28O 2), palmitic acid (C 16H 32O 2), oleic acid (C 18H 34O 2) and stearic acid (C 18H 36O 2), has been measured at the photon energies 81, 356, 511, 662, 1173 and 1332 keV. Experimental values for the molar extinction coefficient, the effective atomic number and the electron density have been derived and compared with theoretical calculations. There is good agreement between experiment and theory.
ERIC Educational Resources Information Center
Halsall, H. B.; Wermeling, J. R.
1982-01-01
Describes an experiment using a high-speed preparative centrifuge and calculator to demonstrate effects of the frictional coefficient of a macromolecule on its rate of transport in a force field and to estimate molecular weight of the macromolecule using an empirical relationship. Background information, procedures, and discussion of results are…
Adler, Jeremy; Parmryd, Ingela
2010-08-01
The Pearson correlation coefficient (PCC) and the Mander's overlap coefficient (MOC) are used to quantify the degree of colocalization between fluorophores. The MOC was introduced to overcome perceived problems with the PCC. The two coefficients are mathematically similar, differing in the use of either the absolute intensities (MOC) or of the deviation from the mean (PCC). A range of correlated datasets, which extend to the limits of the PCC, only evoked a limited response from the MOC. The PCC is unaffected by changes to the offset while the MOC increases when the offset is positive. Both coefficients are independent of gain. The MOC is a confusing hybrid measurement, that combines correlation with a heavily weighted form of co-occurrence, favors high intensity combinations, downplays combinations in which either or both intensities are low and ignores blank pixels. The PCC only measures correlation. A surprising finding was that the addition of a second uncorrelated population can substantially increase the measured correlation, demonstrating the importance of excluding background pixels. Overall, since the MOC is unresponsive to substantial changes in the data and is hard to interpret, it is neither an alternative to nor a useful substitute for the PCC. The MOC is not suitable for making measurements of colocalization either by correlation or co-occurrence. PMID:20653013
The Attenuation of Correlation Coefficients: A Statistical Literacy Issue
ERIC Educational Resources Information Center
Trafimow, David
2016-01-01
Much of the science reported in the media depends on correlation coefficients. But the size of correlation coefficients depends, in part, on the reliability with which the correlated variables are measured. Understanding this is a statistical literacy issue.
Recovering DC coefficients in block-based DCT.
Uehara, Takeyuki; Safavi-Naini, Reihaneh; Ogunbona, Philip
2006-11-01
It is a common approach for JPEG and MPEG encryption systems to provide higher protection for dc coefficients and less protection for ac coefficients. Some authors have employed a cryptographic encryption algorithm for the dc coefficients and left the ac coefficients to techniques based on random permutation lists which are known to be weak against known-plaintext and chosen-ciphertext attacks. In this paper we show that in block-based DCT, it is possible to recover dc coefficients from ac coefficients with reasonable image quality and show the insecurity of image encryption methods which rely on the encryption of dc values using a cryptoalgorithm. The method proposed in this paper combines dc recovery from ac coefficients and the fact that ac coefficients can be recovered using a chosen ciphertext attack. We demonstrate that a method proposed by Tang to encrypt and decrypt MPEG video can be completely broken. PMID:17076416
Sample controllability of impulsive differential systems with random coefficients
NASA Astrophysics Data System (ADS)
Zhang, Shuorui; Sun, Jitao
2016-07-01
In this paper, we investigate the controllability of impulsive differential systems with random coefficients. Impulsive differential systems with random coefficients are a different stochastic model from stochastic differential equations. Sufficient conditions of sample controllability for impulsive differential systems with random coefficients are obtained by using random Sadovskii's fixed-point theorem. Finally, an example is given to illustrate our results.
Coefficients of Association Analogous to Pearson's r for Nonparametric Statistics.
ERIC Educational Resources Information Center
Stavig, Gordon; Acock, Alan C.
1980-01-01
Two r coefficients of association are discussed. One of the coefficients can be applied to any nonparametric test statistic (NTS) in which a normal approximation equation is appropriate. The other coefficient is applicable to any NTS in which exact probabilities are known. (Author/RL)
On the Occurrence of Standardized Regression Coefficients Greater than One.
ERIC Educational Resources Information Center
Deegan, John, Jr.
1978-01-01
It is demonstrated here that standardized regression coefficients greater than one can legitimately occur. Furthermore, the relationship between the occurrence of such coefficients and the extent of multicollinearity present among the set of predictor variables in an equation is examined. Comments on the interpretation of these coefficients are…
Interpretation of Standardized Regression Coefficients in Multiple Regression.
ERIC Educational Resources Information Center
Thayer, Jerome D.
The extent to which standardized regression coefficients (beta values) can be used to determine the importance of a variable in an equation was explored. The beta value and the part correlation coefficient--also called the semi-partial correlation coefficient and reported in squared form as the incremental "r squared"--were compared for variables…
Factors Affecting Coefficient Alpha: A Mini Monte Carlo Study.
ERIC Educational Resources Information Center
Reinhardt, Brian M.
Factors affecting a lower-bound estimate of internal consistency reliability, Cronbach's coefficient alpha, are explored. Theoretically, coefficient alpha is an estimate of the correlation between two tests drawn at random from a pool of items like the items in the test under consideration. As a practical matter, coefficient alpha can be an index…
My Current Thoughts on Coefficient Alpha and Successor Procedures
ERIC Educational Resources Information Center
Cronbach, Lee J.; Shavelson, Richard J.
2004-01-01
In 1997, noting that the 50th anniversary of the publication of "Coefficient Alpha and the Internal Structure of Tests" was fast approaching, Lee Cronbach planned what have become the notes published here. His aim was to point out the ways in which his views on coefficient alpha had evolved, doubting now that the coefficient was the best way of…
Ballistic Coefficient Prediction for Resident Space Objects
NASA Astrophysics Data System (ADS)
Russell, R.; Arora, N.; Vittaldev, V.; Gaylor, D.
2012-09-01
Recent improvements in atmospheric density modeling now provide more confidence in spacecraft ballistic coefficient (BC) estimations, which were previously corrupted by large errors in density. Without attitude knowledge, forecasting the true BC for accurate future state and uncertainty predictions remains elusive. In this paper, our objective is to improve this predictive capability for ballistic coefficients for Resident Space Objects (RSOs), thus improving the existing drag models and associated accuracy of the U.S. Space Object Catalog. To work towards this goal we implement a two-pronged strategy that includes elements of time series analysis and physics based simulations. State-of-the-art empirical time series prediction methods are applied and tested on BC time series in the context of both simulation data and actual data provided by the Air Force. An archive of simulated BC data is generated using custom 6DOF high fidelity simulations for RSOs using plate models for shapes. The simulator includes force and torque perturbations due to the nonspherical Earth, third-body perturbations, SRP, and atmospheric drag. The simulated BC profiles demonstrate significant variation over short time spans (due primarily to varying frontal areas), providing motivation to improve future BC estimation strategies. The 6DOF modeling is intended to provide a physics-based BC data set to complement the BC data set provided by the AF. For the ‘black-box' time series algorithms, a variety of approaches are considered, whereas two prediction models showed the most promising performance: a multi-tone harmonic model and an autoregressive (AR) model. Both the multi-tone harmonic model and the AR model are subjected to multiple levels of optimizations resulting in highly optimized final models that are tuned specifically with the 205 BC time series provided by the AF. Two versions of the AR model are developed based on the model prediction methodology. The second version of the AR
NASA Astrophysics Data System (ADS)
Li, Xiaoqi; Jiang, Huabei
2013-02-01
We present a study through extensive simulation that considers the impact of inhomogeneous optical scattering coefficient distribution on recovery of optical absorption coefficient maps using tomographic photoacoustic data collected from media mimicking breast tissue. We found that while the impact of scattering heterogeneities/targets is modest on photoacoustic recovery of optical absorption coefficients, the impact of scattering contrast caused by adipose tissue, a layer of normal tissue along the boundary of the breast, is dramatic on reconstruction of optical absorption coefficients using photoacoustic data—up to 25.8% relative error in recovering the absorption coefficient is estimated in such cases. To overcome this problem, we propose a new method to enhance photoacoustic recovery of the optical absorption coefficient in heterogeneous media by considering inhomogeneous scattering coefficient distribution provided by diffuse optical tomography (DOT). Results from extensive simulations show that photoacoustic recovery of absorption coefficient maps can be improved considerably with a priori scattering information from DOT.
Dirac-Fock Internal Conversion Coefficients
NASA Astrophysics Data System (ADS)
Band, I. M.; Trzhaskovskaya, M. B.; Nestor, C. W.; Tikkanen, P. O.; Raman, S.
2002-05-01
Internal conversion coefficients (ICCs) obtained from relativistic self-consistent-field Dirac-Fock (DF) calculations are presented. The exchange terms of DF equations are included exactly, both for the interaction between bound electrons and for the interaction between bound and free electrons. Static and dynamic effects resulting from finite nuclear size are taken into account, the latter using the surface current model. Experimental electron-binding energies are used wherever possible. The hole in the atomic shell from which an electron was emitted is not taken into consideration because there is no compelling experimental evidence to warrant it. ICCs are given here for each Z between Z=10 and Z=126; for K, L1, L2, and L3 atomic shells; for nuclear-transition multipolarities E1… E5, M1… M5; and for nuclear-transition energies from ˜1 keV above the L1 threshold to 2000 keV. Also given are the total ICCs. Accurate (≤5%) experimental ICCs ( K and total) are known for 77 transitions with multipolarities E2, M3, E3, M4, or E5. For these transitions, the theoretical DF values are, on average, about 3% lower than the theoretical relativistic Hartree-Fock-Slater (RHFS) values. The DF values are in better agreement with experimental results than the RHFS values.
Transport coefficients of a relativistic plasma
NASA Astrophysics Data System (ADS)
Pike, O. J.; Rose, S. J.
2016-05-01
In this work, a self-consistent transport theory for a relativistic plasma is developed. Using the notation of Braginskii [S. I. Braginskii, in Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 174], we provide semianalytical forms of the electrical resistivity, thermoelectric, and thermal conductivity tensors for a Lorentzian plasma in a magnetic field. This treatment is then generalized to plasmas with arbitrary atomic number by numerically solving the linearized Boltzmann equation. The corresponding transport coefficients are fitted by rational functions in order to make them suitable for use in radiation-hydrodynamic simulations and transport calculations. Within the confines of linear transport theory and on the assumption that the plasma is optically thin, our results are valid for temperatures up to a few MeV. By contrast, classical transport theory begins to incur significant errors above kBT ˜10 keV, e.g., the parallel thermal conductivity is suppressed by 15% at kBT =20 keV due to relativistic effects.
Attenuation coefficients for water quality trading.
Keller, Arturo A; Chen, Xiaoli; Fox, Jessica; Fulda, Matt; Dorsey, Rebecca; Seapy, Briana; Glenday, Julia; Bray, Erin
2014-06-17
Water quality trading has been proposed as a cost-effective approach for reducing nutrient loads through credit generation from agricultural or point source reductions sold to buyers facing costly options. We present a systematic approach to determine attenuation coefficients and their uncertainty. Using a process-based model, we determine attenuation with safety margins at many watersheds for total nitrogen (TN) and total phosphorus (TP) loads as they transport from point of load reduction to the credit buyer. TN and TP in-stream attenuation generally increases with decreasing mean river flow; smaller rivers in the modeled region of the Ohio River Basin had TN attenuation factors per km, including safety margins, of 0.19-1.6%, medium rivers of 0.14-1.2%, large rivers of 0.13-1.1%, and very large rivers of 0.04-0.42%. Attenuation in ditches transporting nutrients from farms to receiving rivers is 0.4%/km for TN, while for TP attenuation in ditches can be up to 2%/km. A 95 percentile safety margin of 30-40% for TN and 6-10% for TP, applied to the attenuation per km factors, was determined from the in-stream sensitivity of load reductions to watershed model parameters. For perspective, over 50 km a 1% per km factor would result in 50% attenuation = 2:1 trading ratio. PMID:24866482
Ghost imaging based on Pearson correlation coefficients
NASA Astrophysics Data System (ADS)
Yu, Wen-Kai; Yao, Xu-Ri; Liu, Xue-Feng; Li, Long-Zhen; Zhai, Guang-Jie
2015-05-01
Correspondence imaging is a new modality of ghost imaging, which can retrieve a positive/negative image by simple conditional averaging of the reference frames that correspond to relatively large/small values of the total intensity measured at the bucket detector. Here we propose and experimentally demonstrate a more rigorous and general approach in which a ghost image is retrieved by calculating a Pearson correlation coefficient between the bucket detector intensity and the brightness at a given pixel of the reference frames, and at the next pixel, and so on. Furthermore, we theoretically provide a statistical interpretation of these two imaging phenomena, and explain how the error depends on the sample size and what kind of distribution the error obeys. According to our analysis, the image signal-to-noise ratio can be greatly improved and the sampling number reduced by means of our new method. Project supported by the National Key Scientific Instrument and Equipment Development Project of China (Grant No. 2013YQ030595) and the National High Technology Research and Development Program of China (Grant No. 2013AA122902).
Reactive sticking coefficients of silane on silicon
Buss, R.J.; Ho, P.; Breiland, W.G.; Coltrin, M.E.
1987-01-01
We have investigated the reaction of room-temperature silane and disilane on a hot polycrystalline silicon surface using both a collision-free molecular beam and a very low pressure CVD cell. Reactive sticking coefficients were obtained from deposition rate data over a wide range of temperatures and silane (disilane) fluxes. The RSCs are substantially less than one, ranging from 6 x 10/sup -5/ to 4 x 10/sup -2/. For silane we observed curved Arrhenius plots with slopes decreasing from approx.60 kcal mol/sup -1/ at low temperatures to approx.2 kcal mol/sup -1/ at higher temperatures. The RSCs are independent of flux (pressure) at 1040/sup 0/C, but vary as flux to the approx.-1/2 power at 710/sup 0/C. A model comprised of a dissociative adsorption mechanism with competing associative desorption and reaction was found to give reasonable agreement. For disilane, we observed RSCs that were roughly ten times higher than those for silane. We also observed a curved Arrhenius plot and a flux dependence at 710/sup 0/C for disilane. 22 refs., 5 figs.
NASA Astrophysics Data System (ADS)
Li, Ai-hua; Liu, Yong; Guo, Yang-yao; Wang, Hui-lin
2008-11-01
Traditional classification methods based on Bayes rule only use spectral information, whereas, other characteristics such as shape, size, situation and pattern are seldom taken into account to extract land use and land cover information. A new method based on spectral, contextual and ancillary information has been proposed in this paper to address to the problem of misclassification. The study area is located in an arid area of northern China. Based on eCognition software, A TM image and a DEM was utilized in this paper to investigate the effectiveness of the image-cognition based on classification method in land use/land cover classification of arid areas. The image was first segmented into a number of objects and then classified as 22 classes based on the spectral, shape, area, spatial position, pattern and context information with the fuzzy logic rules. Finally, the classification method has been proved to be effective and produced an overall accuracy up to 85.3% and a Kappa coefficient of 84%. The classification result suggests that this method is effective and feasible to classify the main types of ground objects in the large complex and arid area for land use survey.
NASA Astrophysics Data System (ADS)
Bailly-Comte, V.; Pistre, S.
2011-12-01
Strategies for groundwater protection mostly use vulnerability maps to contamination; therefore, a lot of methods have been developed since the 90's with a particular attention to operational techniques. These easy-to-use methods are based on the superposition of relative rating systems applied to critical hydrogeological factors; their major drawback is the subjectivity of the determination of the rating scale and the weighting coefficients. Thus, in addition to vulnerability mapping, empirical results given by tracer tests are often needed to better assess groundwater vulnerability to accidental contamination in complex hydrosystems such as karst aquifers. This means that a lot of data about tracer breakthrough curves (BTC) in karst area are now available for hydrologists. In this context, we propose a physical approach to spatially distributed simulation of tracer BTC based on macrodispersive transport in 1D. A new interpretation of tracer tests performed in various media is shown as a validation of our theoretical development. The vulnerability map is then given by the properties of the simulated tracer BTC (modal time, mean residence time, duration over a given concentration threshold etc.). In this way, our method expresses the vulnerability with units, which makes it possible the comparison from one system to another. In addition, previous or new tracer tests can be used as a validation of the map for the same hydrological conditions. Even if this methodology is not limited to karsts hydrosystems, this seems particularly suitable for these complex environments for which understanding the origin of accidental contamination is crucial.
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.
Sasaki, Satoshi; Kobayashi, Minatsu; Ishihara, Junko; Tsugane, Shoichiro
2003-01-01
In this section we described the structure of the self-administered semiquantitative food frequency questionnaire used in the 5-year follow-up survey of the JPHC study, the computation algorithms, and the area-based mean intakes of nutrients and food groups in the subjects of the validation study. The FFQ consists of five sections: 1) semiquantitative frequency questions for rice and miso (fermented soybean paste)-soup, 2) those for alcoholic beverages, 3) those for vitamin supplements, 4) those for foods and beverages, and 5) questions on dietary and cooking behaviors. From the questions, intakes of nutrients and foods by food groups were computed. Although most of them were computed from the frequency and relative portion size indicated in the replies, together with the fixed portion size, a seasonal coefficient was added in the computation of vegetables and fruits. Only frequency of intake and fixed portion size were used for computation of beverages. Sugar and cream added in coffee and tea were computed from the frequency of coffee and tea intake. The intakes of cooking oil, cooking salt (sodium), and salt in noodle-soup were estimated from the questions of relative preference of oil, salt, and noodle-soup. PMID:12701629
Linear and nonlinear optical absorption coefficients of spherical dome shells
NASA Astrophysics Data System (ADS)
Guo, Kangxian; Liu, Guanghui; Huang, Lu; Zheng, Xianyi
2015-08-01
Linear and nonlinear optical absorption coefficients of spherical dome shells are theoretically investigated within analytical wave functions and numerical quantized energy levels. Our results show that the inner radius, the outer radius and the cut-off angle of spherical dome shells have great influences on linear and nonlinear optical absorption coefficients as well as the total optical absorption coefficients. It is found that with the increase of the inner radius and the outer radius, linear and nonlinear optical absorption coefficients exhibit a blueshift and a redshift, respectively. However, with the increase of the cut-off angle, linear and nonlinear optical absorption coefficients do not shift. Besides, the resonant peaks of linear and nonlinear optical absorption coefficients climb up and then decrease with increasing the cut-off angle. The influences of the incident optical intensity on the total optical absorption coefficients are studied. It is found that the bleaching effect occurs at higher incident optical intensity.
Distribution Coefficients of Impurities in Metals
NASA Astrophysics Data System (ADS)
Pearce, J. V.
2014-04-01
Impurities dissolved in very pure metals at the level of parts per million often cause an elevation or depression of the freezing temperature of the order of millikelvins. This represents a significant contribution to the uncertainty of standard platinum resistance thermometer calibrations. An important parameter for characterizing the behavior of impurities is the distribution coefficient , which is the ratio of the solid solubility to liquid solubility. A knowledge of for a given binary system is essential for contemporary methods of evaluating or correcting for the effect of impurities, and it is therefore of universal interest to have the most complete set of values possible. A survey of equilibrium values of (in the low concentration limit) reported in the literature for the International Temperature Scale of 1990 fixed points of Hg, Ga, In, Sn, Zn, Al, Au, Ag, and Cu is presented. In addition, thermodynamic calculations of using MTDATA are presented for 170 binary systems. In total, the combined values of from all available sources for 430 binary systems are presented. In addition, by considering all available values of for impurities in 25 different metal solvents (1300 binary systems) enough data are available to characterize patterns in the value of for a given impurity as a function of its position in the periodic table. This enables prediction of for a significant number of binary systems for which data and calculations are unavailable. By combining data from many sources, values of for solutes (atomic number from 1 to 94) in ITS-90 fixed points from Hg to Cu are suggested, together with some tentative predicted values where literature data and calculations are unavailable.
Calculation and application of combined diffusion coefficients in thermal plasmas.
Murphy, Anthony B
2014-01-01
The combined diffusion coefficient method is widely used to treat the mixing and demixing of different plasma gases and vapours in thermal plasmas, such as welding arcs and plasma jets. It greatly simplifies the treatment of diffusion for many gas mixtures without sacrificing accuracy. Here, three subjects that are important in the implementation of the combined diffusion coefficient method are considered. First, it is shown that different expressions for the combined diffusion coefficients, arising from different definitions for the stoichiometric coefficients that assign the electrons to the two gases, are equivalent. Second, an approach is presented for calculating certain partial differential terms in the combined temperature and pressure diffusion coefficients that can cause difficulties. Finally, a method for applying the combined diffusion coefficients in computational models, which typically require diffusion to be expressed in terms of mass fraction gradients, is given. PMID:24603457
Personal dose-equivalent conversion coefficients for 1252 radionuclides.
Otto, Thomas
2016-01-01
Dose conversion coefficients for radionuclides are useful for routine calculations in radiation protection in industry, medicine and research. They give a simple and often sufficient estimate of dose rates during production, handling and storage of radionuclide sources, based solely on the source's activity. The latest compilation of such conversion coefficients dates from 20 y ago, based on nuclear decay data published 30 y ago. The present publication provides radionuclide-specific conversion coefficients to personal dose based on the most recent evaluations of nuclear decay data for 1252 radionuclides and fluence-to-dose-equivalent conversion coefficients for monoenergetic radiations. It contains previously unknown conversion coefficients for >400 nuclides and corrects those conversion coefficients that were based on erroneous decay schemes. For the first time, estimates for the protection quantity Hp(3) are included. PMID:25349458
Calculation and application of combined diffusion coefficients in thermal plasmas
Murphy, Anthony B.
2014-01-01
The combined diffusion coefficient method is widely used to treat the mixing and demixing of different plasma gases and vapours in thermal plasmas, such as welding arcs and plasma jets. It greatly simplifies the treatment of diffusion for many gas mixtures without sacrificing accuracy. Here, three subjects that are important in the implementation of the combined diffusion coefficient method are considered. First, it is shown that different expressions for the combined diffusion coefficients, arising from different definitions for the stoichiometric coefficients that assign the electrons to the two gases, are equivalent. Second, an approach is presented for calculating certain partial differential terms in the combined temperature and pressure diffusion coefficients that can cause difficulties. Finally, a method for applying the combined diffusion coefficients in computational models, which typically require diffusion to be expressed in terms of mass fraction gradients, is given. PMID:24603457
ANALYTIC FORMS OF THE PERPENDICULAR DIFFUSION COEFFICIENT IN NRMHD TURBULENCE
Shalchi, A.
2015-02-01
In the past different analytic limits for the perpendicular diffusion coefficient of energetic particles interacting with magnetic turbulence were discussed. These different limits or cases correspond to different transport modes describing how the particles are diffusing across the large-scale magnetic field. In the current paper we describe a new transport regime by considering the model of noisy reduced magnetohydrodynamic turbulence. We derive different analytic forms of the perpendicular diffusion coefficient, and while we do this, we focus on the aforementioned new transport mode. We show that for this turbulence model a small perpendicular diffusion coefficient can be obtained so that the latter diffusion coefficient is more than hundred times smaller than the parallel diffusion coefficient. This result is relevant to explain observations in the solar system where such small perpendicular diffusion coefficients have been reported.
Scanning measurement of Seebeck coefficient of a heated sample
Snyder, G. Jeffrey; Iwanaga, Shiho
2016-04-19
A novel scanning Seebeck coefficient measurement technique is disclosed utilizing a cold scanning thermocouple probe tip on heated bulk and thin film samples. The system measures variations in the Seebeck coefficient within the samples. The apparatus may be used for two dimensional mapping of the Seebeck coefficient on the bulk and thin film samples. This technique can be utilized for detection of defective regions, as well as phase separations in the sub-mm range of various thermoelectric materials.
Measuring Furnace/Sample Heat-Transfer Coefficients
NASA Technical Reports Server (NTRS)
Rosch, William R.; Fripp, Archibald L., Jr.; Debnam, William J., Jr.; Woodell, Glenn A.
1993-01-01
Complicated, inexact calculations now unnecessary. Device called HTX used to simulate and measure transfer of heat between directional-solidification crystal-growth furnace and ampoule containing sample of crystalline to be grown. Yields measurement data used to calculate heat-transfer coefficients directly, without need for assumptions or prior knowledge of physical properties of furnace, furnace gas, or specimen. Determines not only total heat-transfer coefficients but also coefficients of transfer of heat in different modes.
Asymptotic coefficients for one-interacting-level Voigt profiles
NASA Astrophysics Data System (ADS)
Cope, D.; Lovett, R. J.
1988-02-01
The asymptotic behavior of general Voigt profiles with general width and shift functions has been determined by Cope and Lovett (1987). The resulting asymptotic coefficients are functions of the perturber/radiator mass ratio; also, the coefficients for the one-interacting-level (OIL) profiles proposed by Ward et al. (1974) were studied. In this paper, the behavior of the OIL asymptotic coefficients for large mass ratio values is determined, thereby providing a complete picture of OIL asymptotics for all mass ratios.
DCFPAK: Dose coefficient data file package for Sandia National Laboratory
Eckerman, K.F.; Leggett, R.W.
1996-07-31
The FORTRAN-based computer package DCFPAK (Dose Coefficient File Package) has been developed to provide electronic access to the dose coefficient data files summarized in Federal Guidance Reports 11 and 12. DCFPAK also provides access to standard information regarding decay chains and assembles dose coefficients for all dosimetrically significant radioactive progeny of a specified radionuclide. DCFPAK was designed for application on a PC but, with minor modifications, may be implemented on a UNIX workstation.
Microscopic formula for transport coefficients of causal hydrodynamics.
Koide, T
2007-06-01
The Green-Kubo-Nakano formula should be modified in relativistic hydrodynamics because of the problem of acausality and the breaking of sum rules. In this Rapid Communication, we propose a formula to calculate the transport coefficients of causal hydrodynamics based on the projection operator method. As concrete examples, we derive the expressions for the diffusion coefficient, the shear viscosity coefficient, and corresponding relaxation times. PMID:17677204
PAC91 - PROPERTIES AND COEFFICIENTS 1991
NASA Technical Reports Server (NTRS)
Mcbride, B. J.
1994-01-01
The two principal functions of PAC91 are to provide a means of generating theoretical thermodynamic functions from molecular constant data and to supply a means of fitting these functions to empirical equations by using a least-squares fit. The coefficients obtained from the fit may then be used to generate a library of thermodynamic data in a uniform and easy-to-use format for use in other computer codes. Several large compilations of selected or calculated thermodynamic data currently exist. Nevertheless, there is a continuing need for additional calculations due to the discovery of new species, the revision of existing molecular constant data and structural parameters, the need for data at temperatures other than those already published, the availability of new or revised heats of formation, dissociation or transition, and the revision of fundamental constants or atomic weights. Calculations may also be needed to compare the results of assuming various possible forms of the partition function. In addition, there is often a preference for thermodynamic data in functional rather than tabular form. In order to satisfy these needs, the PAC91 program can perform any combination of the following: (1) calculate thermodynamic functions (heat capacity, enthalpy, entropy, and Gibbs energy) for any set of 1 to 202 temperatures, (2) obtain a least-squares fit of the first three of these functions (either individually, two at a time, or all three simultaneously) for up to eight temperature intervals, and (3) calculate, as a function of temperature, heats of formation and equilibrium constants from assigned reference elements. The thermodynamic functions for ideal gases may be calculated from molecular constant data using one of several partition function variations provided by the program. For monatomic gases, one of three partition function cutoff techniques may be selected by the user, and unobserved but predicted electronic energy levels may be included by the program
Aerosol Angstrom Absorption Coefficient Comparisons during MILAGRO.
NASA Astrophysics Data System (ADS)
Marley, N. A.; Marchany-Rivera, A.; Kelley, K. L.; Mangu, A.; Gaffney, J. S.
2007-12-01
aerosol Angstrom absorption exponents by linear regression over the entire UV-visible spectral range. These results are compared to results obtained from the absorbance measurements obtained in the field. The differences in calculated Angstrom absorption exponents between the field and laboratory measurements are attributed partly to the differences in time resolution of the sample collection resulting in heavier particle pileup on the filter surface of the 12-hour samples. Some differences in calculated results can also be attributed to the presence of narrow band absorbers below 400 nm that do not fall in the wavelengths covered by the 7 wavelengths of the aethalometer. 1. Marley, N.A., J.S. Gaffney, J.C. Baird, C.A. Blazer, P.J. Drayton, and J.E. Frederick, "The determination of scattering and absorption coefficients of size-fractionated aerosols for radiative transfer calculations." Aerosol Sci. Technol., 34, 535-549, (2001). This work was conducted as part of the Department of Energy's Atmospheric Science Program as part of the Megacity Aerosol Experiment - Mexico City during MILAGRO. This research was supported by the Office of Science (BER), U.S. Department of Energy Grant No. DE-FG02-07ER64329. We also wish to thank Mexican Scientists and students for their assistance from the Instituto Mexicano de Petroleo (IMP) and CENICA.
Diffusion coefficient of three-dimensional Yukawa liquids
NASA Astrophysics Data System (ADS)
Dzhumagulova, K. N.; Ramazanov, T. S.; Masheeva, R. U.
2013-11-01
The purpose of this work is an investigation of the diffusion coefficient of the dust component in complex plasma. The computer simulation of the Yukawa liquids was made on the basis of the Langevin equation, which takes into account the influence of buffer plasma on the dust particles dynamics. The Green-Kubo relation was used to calculate the diffusion coefficient. Calculations of the diffusion coefficient for a wide range of the system parameters were performed. Using obtained numerical data, we constructed the interpolation formula for the diffusion coefficient. We also show that the interpolation formula correctly describes experimental data obtained under microgravity conditions.
Coefficients of convergent multiple Walsh-Paley series
Plotnikov, Mikhail G
2012-09-30
The paper is concerned with the behaviour of the coefficients of multiple Walsh-Paley series that are cube convergent to a finite sum. It is shown that even an everywhere convergent series of this kind may contain coefficients with numbers from a sufficiently large set that grow faster than any preassigned sequence. By Cohen's theorem, this sort of thing cannot happen for multiple trigonometric series that are cube convergent on a set of full measure - their coefficients cannot grow even exponentially. Null subsequences of coefficients are determined for multiple Walsh-Paley series that are cube convergent on a set of definite measure. Bibliography: 18 titles.
Discharge coefficients of impingement and film cooling holes
NASA Astrophysics Data System (ADS)
Chu, T.; Brown, A.; Garret, S.
1985-03-01
In this article measurements of fluid flow through impingement and film cooling holes for typical turbine blade cooling systems are presented. The purpose of the measurements was to determine hole discharge coefficients over a range of Reynolds numbers from 5,000 to 30,000 and to observe in this range the dependence of discharge coefficient on Reynolds number. The effect of hole geometry, that is, sharp edged inlet or corner radius inlet, on discharge coefficients is also measured. Correlations relating discharge coefficients to Reynolds number, corner radius to hole diameter ratio, and blowing parameter are suggested.
Diffusion coefficient of three-dimensional Yukawa liquids
Dzhumagulova, K. N.; Ramazanov, T. S.; Masheeva, R. U.
2013-11-15
The purpose of this work is an investigation of the diffusion coefficient of the dust component in complex plasma. The computer simulation of the Yukawa liquids was made on the basis of the Langevin equation, which takes into account the influence of buffer plasma on the dust particles dynamics. The Green–Kubo relation was used to calculate the diffusion coefficient. Calculations of the diffusion coefficient for a wide range of the system parameters were performed. Using obtained numerical data, we constructed the interpolation formula for the diffusion coefficient. We also show that the interpolation formula correctly describes experimental data obtained under microgravity conditions.
Heat transfer coefficients for drying in pulsating flows
Fraenkel, S.L.
1998-05-01
Pulsating flows generated by a Rijke type combustor are studied for drying of grains and food particles. It is assumed that the velocity fluctuations are the main factor in the enhancement of the drying process. The heat transfer coefficients for drying in vibrating beds are utilized to estimate the heat transfer coefficients of fixed beds in pulsating and permeating flows and are compared to the steady flow heat transfer coefficients obtained for solid porous bodies, after perturbing the main flow. The cases considered are compared to the convective heat transfer coefficients employed in non-pulsating drying.
Quantum Non-Markovian Langevin Equations and Transport Coefficients
Sargsyan, V.V.; Antonenko, N.V.; Kanokov, Z.; Adamian, G.G.
2005-12-01
Quantum diffusion equations featuring explicitly time-dependent transport coefficients are derived from generalized non-Markovian Langevin equations. Generalized fluctuation-dissipation relations and analytic expressions for calculating the friction and diffusion coefficients in nuclear processes are obtained. The asymptotic behavior of the transport coefficients and correlation functions for a damped harmonic oscillator that is linearly coupled in momentum to a heat bath is studied. The coupling to a heat bath in momentum is responsible for the appearance of the diffusion coefficient in coordinate. The problem of regression of correlations in quantum dissipative systems is analyzed.
Measurement of the extinction coefficients of magnetic fluids
2011-01-01
A novel spectral transmittance approach for measuring the extinction coefficient of magnetic fluids is proposed. The measuring principle and accuracy of the approach are analysed. Experiments are conducted to measure the extinction coefficient of magnetic fluids with different particle volume fractions. The relative uncertainty of experimental data is less than 1.8%. The experimental results indicate that the extinction coefficient of magnetic fluids increases with increase of the volume fraction of suspended magnetic nanoparticles and the optical properties of the particle material have a significant effect on the extinction coefficient of the magnetic fluids. PMID:21711742
Process controls on event runoff coefficients in Austria
NASA Astrophysics Data System (ADS)
Merz, R.; Blöschl, G.
2009-04-01
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 longterm 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.
Binary-YORP Coefficients for Known Asteroid Shapes
NASA Astrophysics Data System (ADS)
McMahon, Jay W.; Scheeres, D. J.
2012-10-01
The binary YORP (bYORP) effect has been hypothesized to be a significant factor in the evolution of near-Earth binary asteroid systems (Cuk and Burns, Icarus, v.176, pp.418-431, 2005; McMahon and Scheeres, CMDA, v.106, pp.261-300, 2010). However, understanding of the coefficient values for realistic asteroid shapes is lacking due to the small number of shape models available for the generally smaller secondary asteroids. Until now, we have only calculated the coefficients based on the shape of 1999 KW4 Beta, although various studies by other authors have computed coefficients for artificially generated asteroids based on Gaussian Spheres and some shape models without self-shadowing (Steinberg and Sari, The Astronomical Journal, v.141, pp.55-64, 2011). We also scaled the 1999 KW4 Beta coefficients to other binary systems with no knowledge of the other systems' secondary shapes in order to make evolutionary predictions (McMahon and Scheeres, Icarus Vol. 209, pp 494-509, 2010). In this study, we compute the bYORP coefficient for a range of asteroid shapes, using these as a stand-in for actual secondaries. This allows us to circumvent the lack of information on binary asteroid secondaries and to develop a richer database of realistic coefficients. While this approach may miss some key features of binary secondaries, at the least it provides some statistics on the expected variability of the bYORP coefficient. We analyze all available asteroid shape models on the PDS-SBN, including radar-based shape models and models estimated from past spacecraft missions. The coefficients are computed with an updated algorithm that includes the effects of self-shadowing. We also present the coefficients for perturbed versions of the available shape models, which give effective error bars to the computed coefficients due to inexact shape models. Finally, we discuss the dynamical implications of the derived bYORP coefficients on binary asteroid evolution.
Testing the Difference of Correlated Agreement Coefficients for Statistical Significance
ERIC Educational Resources Information Center
Gwet, Kilem L.
2016-01-01
This article addresses the problem of testing the difference between two correlated agreement coefficients for statistical significance. A number of authors have proposed methods for testing the difference between two correlated kappa coefficients, which require either the use of resampling methods or the use of advanced statistical modeling…
A method for obtaining coefficients of compositional inverse generating functions
NASA Astrophysics Data System (ADS)
Kruchinin, Dmitry V.; Shablya, Yuriy V.; Kruchinin, Vladimir V.; Shelupanov, Alexander A.
2016-06-01
The aim of this paper is to show how to obtain expressions for coefficients of compositional inverse generating functions in explicit way. The method is based on the Lagrange inversion theorem and composita of generating functions. Also we give a method of obtaining expressions for coefficients of reciprocal generating functions and consider some examples.
Asymptotically Distribution-Free (ADF) Interval Estimation of Coefficient Alpha
ERIC Educational Resources Information Center
Maydeu-Olivares, Alberto; Coffman, Donna L.; Hartmann, Wolfgang M.
2007-01-01
The point estimate of sample coefficient alpha may provide a misleading impression of the reliability of the test score. Because sample coefficient alpha is consistently biased downward, it is more likely to yield a misleading impression of poor reliability. The magnitude of the bias is greatest precisely when the variability of sample alpha is…
Temperature dependence of the diffusion coefficient of nanoparticles
NASA Astrophysics Data System (ADS)
Rudyak, V. Ya.; Dubtsov, S. N.; Baklanov, A. M.
2008-06-01
The temperature dependence of the diffusion coefficient of nanoparticles in gases has been experimentally studied. It is established that this dependence significantly differs from that predicted by various correlations, in particular, by the Cunningham-Millikan-Davies correlation that is used as an instrumental basis for virtually all methods of measurement of the diffusion coefficient in aerosols.
Delimiting Coefficient a from Internal Consistency and Unidimensionality
ERIC Educational Resources Information Center
Sijtsma, Klaas
2015-01-01
I discuss the contribution by Davenport, Davison, Liou, & Love (2015) in which they relate reliability represented by coefficient a to formal definitions of internal consistency and unidimensionality, both proposed by Cronbach (1951). I argue that coefficient a is a lower bound to reliability and that concepts of internal consistency and…
REE and Strontium Partition Coefficients for Nakhla Pyroxenes
NASA Technical Reports Server (NTRS)
Oe, K.; McKay, G.; Le, L.
2001-01-01
We present new partition coefficients for REE and Sr determined using a synthetic melt that crystallizes pyroxenes very similar in composition to Nakhla pyroxene cores. We believe these are the most appropriate partition coefficients to use in studying Nakhla Additional information is contained in the original extended abstract..
Crop Coefficients of Some Selected Crops of Andhra Pradesh
NASA Astrophysics Data System (ADS)
Reddy, K. Chandrasekhar; Arunajyothy, S.; Mallikarjuna, P.
2015-06-01
Precise information on crop coefficients for estimating crop evapotranspiration (ETc) for regional scale irrigation planning is a major impediment in many regions. Crop coefficients suggested based on lysimeter data by earlier investigators have to be locally calibrated to account for the differences in the crop canopy under given climatic conditions. In the present study crop coefficients were derived based on reference crop evapotranspiration (ET0) estimated from Penman-Monteith equation and lysimeter measured ETc for groundnut, paddy, tobacco, sugarcane and castor crops at Tirupati, Nellore, Rajahmundry, Anakapalli and Rajendranagar centers of Andhra Pradesh respectively. Crop coefficients derived were compared with those recommended by FAO-56. The mean crop coefficients at different stages of growth were significantly different from those of FAO-56 curve though a similar trend was observed. A third order polynomial crop coefficient model has therefore been developed as a function of time (days after sowing the crop) for deriving suitable crop coefficients. The crop coefficient models suggested may be adopted to estimate crop evapotranspiration in the study area with reasonable degree of accuracy.
A program to compute aquifer-response coefficients
Maddock, Thomas
1974-01-01
An alternating direction technique is used to solve finite difference equations approximating the flow of water in an aquifer. The solutions produce response coefficients relating pumping from wells to drawdowns within those wells. The product of the response coefficient with the pumping values produces a linear algebraic technological function that can be used for integrating hydrologic phenomena into planning and management models.
Graphical Solution of the Monic Quadratic Equation with Complex Coefficients
ERIC Educational Resources Information Center
Laine, A. D.
2015-01-01
There are many geometrical approaches to the solution of the quadratic equation with real coefficients. In this article it is shown that the monic quadratic equation with complex coefficients can also be solved graphically, by the intersection of two hyperbolas; one hyperbola being derived from the real part of the quadratic equation and one from…
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.
Calculation of fusion product angular correlation coefficients for fusion plasmas
Murphy, T.J.
1987-08-01
The angular correlation coefficients for fusion products are calculated in the cases of Maxwellian and beam-target plasmas. Measurement of these coefficients as a localized ion temperature or fast-ion diagnostic is discussed. 8 refs., 7 figs., 1 tab.
The dyadic diffraction coefficient for a curved edge
NASA Technical Reports Server (NTRS)
Kouyoumjian, R. G.; Pathak, P. H.
1974-01-01
A compact dyadic diffraction coefficient for electromagnetic waves obliquely incident on a curved edge formed by perfectly conducting curved or plane surfaces is obtained. This diffraction coefficent remains valid in the transition regions adjacent to shadow and reflection boundaries, where the diffraction coefficients of Keller's original theory fail. The method is on Keller's method of the canonical problem, which in this case is the perfectly conducting wedge illuminated by plane, cylindrical, conical, and spherical waves. When the proper ray fixed coordinate system is introduced, the dyadic diffraction coefficient for the wedge is found to be the sum of only two dyads, and it is shown that this is also true for the dyadic diffraction coefficients of higher order edges. One dyad contains the acoustic soft diffraction coefficient; the other dyad contains the acoustic hard diffraction coefficient. The expressions for the acoustic wedge diffraction coefficients contain Fresnel integrals, which ensure that the total field is continuous at shadow and reflection boundaries. The diffraction coefficients have the same form for the different types of edge illumination; only the arguments of the Fresnel integrals are different. Since diffraction is a local phenomenon, and locally the curved edge structure is wedge shaped, this result is readily extended to the curved edge.
Biases and Standard Errors of Standardized Regression Coefficients
ERIC Educational Resources Information Center
Yuan, Ke-Hai; Chan, Wai
2011-01-01
The paper obtains consistent standard errors (SE) and biases of order O(1/n) for the sample standardized regression coefficients with both random and given predictors. Analytical results indicate that the formulas for SEs given in popular text books are consistent only when the population value of the regression coefficient is zero. The sample…
Crop coefficient development and application to an evapotranspiration network
Technology Transfer Automated Retrieval System (TEKTRAN)
Crop coefficients derived from properly designed, operated, and maintained lysimeters provide the most accurate values throughout the growing season and are critical in the computation of hourly and daily,regionally based, crop evapotranspiration (ET) values. Multi-stage crop coefficients can be der...
A Method for Maximizing the Internal Consistency Coefficient Alpha.
ERIC Educational Resources Information Center
Pepin, Michel
This paper presents three different ways of computing the internal consistency coefficient alpha for a same set of data. The main objective of the paper is the illustration of a method for maximizing coefficient alpha. The maximization of alpha can be achieved with the aid of a principal component analysis. The relation between alpha max. and the…
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…
Visualising the Roots of Quadratic Equations with Complex Coefficients
ERIC Educational Resources Information Center
Bardell, Nicholas S.
2014-01-01
This paper is a natural extension of the root visualisation techniques first presented by Bardell (2012) for quadratic equations with real coefficients. Consideration is now given to the familiar quadratic equation "y = ax[superscript 2] + bx + c" in which the coefficients "a," "b," "c" are generally…
Factor Scores, Structure and Communality Coefficients: A Primer
ERIC Educational Resources Information Center
Odum, Mary
2011-01-01
(Purpose) The purpose of this paper is to present an easy-to-understand primer on three important concepts of factor analysis: Factor scores, structure coefficients, and communality coefficients. Given that statistical analyses are a part of a global general linear model (GLM), and utilize weights as an integral part of analyses (Thompson, 2006;…
Nondestructive Method For Measuring The Scattering Coefficient Of Bulk Material
NASA Astrophysics Data System (ADS)
Groenhuis, R. A. J.; ten Bosch, J. J.
1981-05-01
During demineralization and remineralization of dental enamel its structure changes resulting in a change of the absorption and scattering coefficients of the enamel. By measuring these coefficients during demineralization and remineralization these processes can be monitored in a non-destructive way. For this purpose an experimental arrangement was made: a fibre illuminates a spot on the sample with monochromatic light with a wave-length between 400 nm and 700 nm; a photomultiplier measures the luminance of the light back-scattered by the sample as a function of the distance from the measuring snot to the spot of illumination. In a Monte Carlo-model this luminance is simulated using the same geometry given the scattering and absorption coefficients in a sample. Then the scattering and absorption coefficients in the sample are determined by selecting the theoretical curve fitting the experimental one. Scattering coefficients below 10 mm-1 and absorption coefficients obtained with this method on calibration samples correspond well with those obtained with another method. Scattering coefficients above 10 mm-1 (paper samples) were measured ton low. This perhaps is caused by the anisotropic structure of paper sheets. The method is very suitable to measure the scattering and absorption coefficients of bulk materials.
A Coefficient for Measuring the Agreement on Bipolar Rating Scales.
ERIC Educational Resources Information Center
Viernstein, Nikolaus
1990-01-01
A new coefficient--psi-star--is presented for measuring agreement on bidirectional response continua. The coefficient is designed to measure agreement in larger square contingency tables with even numbers of rows and columns. Advantages of the procedure are discussed. (SLD)
Micro- and macroscale coefficients of friction of cementitious materials
Lomboy, Gilson; Sundararajan, Sriram; Wang, Kejin
2013-12-15
Millions of metric tons of cementitious materials are produced, transported and used in construction each year. The ease or difficulty of handling cementitious materials is greatly influenced by the material friction properties. In the present study, the coefficients of friction of cementitious materials were measured at the microscale and macroscale. The materials tested were commercially-available Portland cement, Class C fly ash, and ground granulated blast furnace slag. At the microscale, the coefficient of friction was determined from the interaction forces between cementitious particles using an Atomic Force Microscope. At the macroscale, the coefficient of friction was determined from stresses on bulk cementitious materials under direct shear. The study indicated that the microscale coefficient of friction ranged from 0.020 to 0.059, and the macroscale coefficient of friction ranged from 0.56 to 0.75. The fly ash studied had the highest microscale coefficient of friction and the lowest macroscale coefficient of friction. -- Highlights: •Microscale (interparticle) coefficient of friction (COF) was determined with AFM. •Macroscale (bulk) COF was measured under direct shear. •Fly ash had the highest microscale COF and the lowest macroscale COF. •Portland cement against GGBFS had the lowest microscale COF. •Portland cement against Portland cement had the highest macroscale COF.
Abney, Mark
2009-01-01
Summary: Computing the probability of identity by descent sharing among n genes given only the pedigree of those genes is a computationally challenging problem, if n or the pedigree size is large. Here, I present a novel graphical algorithm for efficiently computing all generalized kinship coefficients for n genes. The graphical description transforms the problem from doing many recursion on the pedigree to doing a single traversal of a structure referred to as the kinship graph. Availability: The algorithm is implemented for n = 4 in the software package IdCoefs at http://home.uchicago.edu/abney/Software.html. Contact: abney@bsd.uchicago.edu Supplementary Information:Supplementary data are available at Bioinformatics online. PMID:19359355
Su, Jing-Wei; Lin, Yang-Hsien; Chiang, Chun-Ping; Lee, Jang-Ming; Hsieh, Chao-Mao; Hsieh, Min-Shu; Yang, Pei-Wen; Wang, Chen-Ping; Tseng, Ping-Huei; Lee, Yi-Chia; Sung, Kung-Bin
2015-01-01
The progression of epithelial precancers into cancer is accompanied by changes of tissue and cellular structures in the epithelium. Correlations between the structural changes and scattering coefficients of esophageal epithelia were investigated using quantitative phase images and the scattering-phase theorem. An ex vivo study of 14 patients demonstrated that the average scattering coefficient of precancerous epithelia was 37.8% higher than that of normal epithelia from the same patient. The scattering coefficients were highly correlated with morphological features including the cell density and the nuclear-to-cytoplasmic ratio. A high interpatient variability in scattering coefficients was observed and suggests identifying precancerous lesions based on the relative change in scattering coefficients. PMID:26504630
Direct Extraction of One-loop Integral Coefficients
Forde, Darren
2007-04-16
We present a general procedure for obtaining the coefficients of the scalar bubble and triangle integral functions of one-loop amplitudes. Coefficients are extracted by considering two-particle and triple unitarity cuts of the corresponding bubble and triangle integral functions. After choosing a specific parameterization of the cut loop momentum we can uniquely identify the coefficients of the desired integral functions simply by examining the behavior of the cut integrand as the unconstrained parameters of the cut loop momentum approach infinity. In this way we can produce compact forms for scalar integral coefficients. Applications of this method are presented for both QCD and electroweak processes, including an alternative form for the recently computed three-mass triangle coefficient in the six-photon amplitude A{sub 6}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup -}, 6{sup +}). The direct nature of this extraction procedure allows for a very straightforward automation of the procedure.
Determination of absolute internal conversion coefficients using the SAGE spectrometer
NASA Astrophysics Data System (ADS)
Sorri, J.; Greenlees, P. T.; Papadakis, P.; Konki, J.; Cox, D. M.; Auranen, K.; Partanen, J.; Sandzelius, M.; Pakarinen, J.; Rahkila, P.; Uusitalo, J.; Herzberg, R.-D.; Smallcombe, J.; Davies, P. J.; Barton, C. J.; Jenkins, D. G.
2016-03-01
A non-reference based method to determine internal conversion coefficients using the SAGE spectrometer is carried out for transitions in the nuclei of 154Sm, 152Sm and 166Yb. The Normalised-Peak-to-Gamma method is in general an efficient tool to extract internal conversion coefficients. However, in many cases the required well-known reference transitions are not available. The data analysis steps required to determine absolute internal conversion coefficients with the SAGE spectrometer are presented. In addition, several background suppression methods are introduced and an example of how ancillary detectors can be used to select specific reaction products is given. The results obtained for ground-state band E2 transitions show that the absolute internal conversion coefficients can be extracted using the methods described with a reasonable accuracy. In some cases of less intense transitions only an upper limit for the internal conversion coefficient could be given.
A new correlation coefficient for bivariate time-series data
NASA Astrophysics Data System (ADS)
Erdem, Orhan; Ceyhan, Elvan; Varli, Yusuf
2014-11-01
The correlation in time series has received considerable attention in the literature. Its use has attained an important role in the social sciences and finance. For example, pair trading in finance is concerned with the correlation between stock prices, returns, etc. In general, Pearson’s correlation coefficient is employed in these areas although it has many underlying assumptions which restrict its use. Here, we introduce a new correlation coefficient which takes into account the lag difference of data points. We investigate the properties of this new correlation coefficient. We demonstrate that it is more appropriate for showing the direction of the covariation of the two variables over time. We also compare the performance of the new correlation coefficient with Pearson’s correlation coefficient and Detrended Cross-Correlation Analysis (DCCA) via simulated examples.
Su, Jing-Wei; Lin, Yang-Hsien; Chiang, Chun-Ping; Lee, Jang-Ming; Hsieh, Chao-Mao; Hsieh, Min-Shu; Yang, Pei-Wen; Wang, Chen-Ping; Tseng, Ping-Huei; Lee, Yi-Chia; Sung, Kung-Bin
2015-10-01
The progression of epithelial precancers into cancer is accompanied by changes of tissue and cellular structures in the epithelium. Correlations between the structural changes and scattering coefficients of esophageal epithelia were investigated using quantitative phase images and the scattering-phase theorem. An ex vivo study of 14 patients demonstrated that the average scattering coefficient of precancerous epithelia was 37.8% higher than that of normal epithelia from the same patient. The scattering coefficients were highly correlated with morphological features including the cell density and the nuclear-to-cytoplasmic ratio. A high interpatient variability in scattering coefficients was observed and suggests identifying precancerous lesions based on the relative change in scattering coefficients. PMID:26504630
Nonlinear Varying Coefficient Models with Applications to Studying Photosynthesis.
Kürüm, Esra; Li, Runze; Wang, Yang; SEntürk, Damla
2014-03-01
Motivated by a study on factors affecting the level of photosynthetic activity in a natural ecosystem, we propose nonlinear varying coefficient models, in which the relationship between the predictors and the response variable is allowed to be nonlinear. One-step local linear estimators are developed for the nonlinear varying coefficient models and their asymptotic normality is established leading to point-wise asymptotic confidence bands for the coefficient functions. Two-step local linear estimators are also proposed for cases where the varying coefficient functions admit different degrees of smoothness; bootstrap confidence intervals are utilized for inference based on the two-step estimators. We further propose a generalized F test to study whether the coefficient functions vary over a covariate. We illustrate the proposed methodology via an application to an ecology data set and study the finite sample performance by Monte Carlo simulation studies. PMID:24976756
Nonlinear Varying Coefficient Models with Applications to Studying Photosynthesis
Kürüm, Esra; Li, Runze; Wang, Yang; ŞEntürk, Damla
2014-01-01
Motivated by a study on factors affecting the level of photosynthetic activity in a natural ecosystem, we propose nonlinear varying coefficient models, in which the relationship between the predictors and the response variable is allowed to be nonlinear. One-step local linear estimators are developed for the nonlinear varying coefficient models and their asymptotic normality is established leading to point-wise asymptotic confidence bands for the coefficient functions. Two-step local linear estimators are also proposed for cases where the varying coefficient functions admit different degrees of smoothness; bootstrap confidence intervals are utilized for inference based on the two-step estimators. We further propose a generalized F test to study whether the coefficient functions vary over a covariate. We illustrate the proposed methodology via an application to an ecology data set and study the finite sample performance by Monte Carlo simulation studies. PMID:24976756
Bounce resonance diffusion coefficients for spatially confined waves
NASA Astrophysics Data System (ADS)
Li, Xinxin; Tao, Xin; Lu, Quanmin; Dai, Lei
2015-11-01
Theoretical bounce resonance diffusion coefficients from interactions between electrons and spatially confined waves are derived and validated. Roberts and Schulz bounce resonance diffusion coefficients assume waves to be present on the whole bounce trajectory of particles; therefore, they are not directly applicable to waves that have a finite spatial extent. We theoretically derive and numerically validate a new set of bounce resonance diffusion coefficients for spatially confined waves. We apply our analysis to magnetosonic waves, which are confined to equatorial regions, using a previously published magnetosonic wave model. We find that the bounce resonance diffusion coefficients are comparable to the gyroresonance diffusion coefficients. We conclude that bounce resonance diffusion with magnetosonic waves might play an important role in relativistic electron dynamics.
[Characteristics and Parameterization for Atmospheric Extinction Coefficient in Beijing].
Chen, Yi-na; Zhao, Pu-sheng; He, Di; Dong, Fan; Zhao, Xiu-juan; Zhang, Xiao-ling
2015-10-01
In order to study the characteristics of atmospheric extinction coefficient in Beijing, systematic measurements had been carried out for atmospheric visibility, PM2.5 concentration, scattering coefficient, black carbon, reactive gases, and meteorological parameters from 2013 to 2014. Based on these data, we compared some published fitting schemes of aerosol light scattering enhancement factor [ f(RH)], and discussed the characteristics and the key influence factors for atmospheric extinction coefficient. Then a set of parameterization models of atmospheric extinction coefficient for different seasons and different polluted levels had been established. The results showed that aerosol scattering accounted for more than 94% of total light extinction. In the summer and autumn, the aerosol hygroscopic growth caused by high relative humidity had increased the aerosol scattering coefficient by 70 to 80 percent. The parameterization models could reflect the influencing mechanism of aerosol and relative humidity upon ambient light extinction, and describe the seasonal variations of aerosol light extinction ability. PMID:26841588
The solid-phase diffusion coefficient (Dm) and material-air partition coefficient (Kma) are key parameters for characterizing the sources and transport of semivolatile organic compounds (SVOCs) in the indoor environment. In this work, a new experimental method was developed to es...
ERIC Educational Resources Information Center
Harris, Richard J.
Interpretation of emergent variables on the basis of structure coefficients (zero order correlations between original and emergent variables) is potentially very misleading and should be avoided in favor of interpretation on the basis of scoring coefficients. This is most apparent in multiple regression analysis and its special case, two-group…
Michel, C C
1980-01-01
1. Single capillaries in the mesentery of pithed frogs were perfused with frog Ringer solutions containing various concentrations of bovine serum albumin and myoglobin. Filtration coefficients (Lp) of the capillary wall were determined from measurements of fluid filtration rate at a series of different capillary pressures (Michel, Mason, Curry & Tooke, 1974). The osmotic reflexion coefficients (sigma) to albumin and myoglobin were determined by comparing the effective osmotic pressure exerted by these solutes across the capillary walls with their osmotic pressures in a membrane osmometer. 2. Lp and sigma to albumin were measured in eighteen vessels at different sites in the capillary bed with the tissue temperature in the range of 20-24 degrees C. Lp varied from 1.5 x 10(-3) to 15 x 10(-3) micrometer sec-1 cm H2O-1 having a higher mean value in nine venous capillaries (11.33 x 10(-3) micrometer sec-1 cm H2O-1) than in nine arterial and mid-capillaries (4.83 x 10(-3) micrometer sec-1 cm H2O-1). For all eighteen vessels sigma to albumin had a mean value of 0.816 (S.E. of mean +/- 0.027). There was no correlation between Lp and sigma. The mean value of sigma for the venous capillaries was 0.841 (S.E. of mean +/- 0.04) and the other nine vessels 0.802 (S.E. of mean +/- 0.034). 3. The osmotic reflexion coefficient to myoglobin was measured in seven different capillaries and found to have a mean value of 0.348 (S.E. of mean +/- 0.012) at 20-24 degrees C. The Lp of the capillaries varied from 3.0 x 10(-3) to 10.5 x 10(-3) micrometer sec-1 cm H2O-1. There was no correlation between sigma for myoglobin and Lp. 4. The method of Curry, Mason & Michel (1976) was used to measure sigma for urea in eight capillaries at 20-24 degrees C (sigma for albumin was also measured in two of these vessels). The mean value of sigma for urea was 0.061 (S.E. of mean +/- 0.012). The exclusive water channel (Curry et al. 1976) was calculated to have a value of 0.209 x 10(-3) micrometer sec-1 H2O
Dynamic sagittal flexibility coefficients of the human cervical spine.
Ivancic, Paul C; Ito, Shigeki; Panjabi, Manohar M
2007-07-01
The goal of the present study was to determine the dynamic sagittal flexibility coefficients, including coupling coefficients, throughout the human cervical spine using rear impacts. A biofidelic whole cervical spine model (n=6) with muscle force replication and surrogate head was rear impacted at 5 g peak horizontal accelerations of the T1 vertebra within a bench-top mini-sled. The dynamic main and coupling sagittal flexibility coefficients were calculated at each spinal level, head/C1 to C7/T1. The average flexibility coefficients were statistically compared (p<0.05) throughout the cervical spine. To validate the coefficients, the average computed displacement peaks, obtained using the average flexibility matrices and the measured load vectors, were statistically compared to the measured displacement peaks. The computed and measured displacement peaks showed good overall agreement, thus validating the computed flexibility coefficients. These peaks could not be statistically differentiated, with the exception of extension rotation at head/C1 and posterior shear translation at C7/T1. Head/C1 was significantly more flexible than all other spinal levels. The cervical spine was generally more flexible in posterior shear, as compared to axial compression. The coupling coefficients indicated that extension moment caused coupled posterior shear translation while posterior shear force caused coupled extension rotation. The present results may be used towards the designs of anthropometric test dummies and mathematical models that better simulate the cervical spine response during dynamic loading. PMID:17140545
An analytical solution for quantum size effects on Seebeck coefficient
NASA Astrophysics Data System (ADS)
Karabetoglu, S.; Sisman, A.; Ozturk, Z. F.
2016-03-01
There are numerous experimental and numerical studies about quantum size effects on Seebeck coefficient. In contrast, in this study, we obtain analytical expressions for Seebeck coefficient under quantum size effects. Seebeck coefficient of a Fermi gas confined in a rectangular domain is considered. Analytical expressions, which represent the size dependency of Seebeck coefficient explicitly, are derived in terms of confinement parameters. A fundamental form of Seebeck coefficient based on infinite summations is used under relaxation time approximation. To obtain analytical results, summations are calculated using the first two terms of Poisson summation formula. It is shown that they are in good agreement with the exact results based on direct calculation of summations as long as confinement parameters are less than unity. The analytical results are also in good agreement with experimental and numerical ones in literature. Maximum relative errors of analytical expressions are less than 3% and 4% for 2D and 1D cases, respectively. Dimensional transitions of Seebeck coefficient are also examined. Furthermore, a detailed physical explanation for the oscillations in Seebeck coefficient is proposed by considering the relative standard deviation of total variance of particle number in Fermi shell.
Factors influencing the stream-aquifer flow exchange coefficient.
Morel-Seytoux, Hubert J; Mehl, Steffen; Morgado, Kyle
2014-01-01
Knowledge of river gain from or loss to a hydraulically connected water table aquifer is crucial in issues of water rights and also when attempting to optimize conjunctive use of surface and ground waters. Typically in groundwater models this exchange flow is related to a difference in head between the river and some point in the aquifer, through a "coefficient." This coefficient has been defined differently as well as the location for the head in the aquifer. This paper proposes a new coefficient, analytically derived, and a specific location for the point where the aquifer head is used in the difference. The dimensionless part of the coefficient is referred to as the SAFE (stream-aquifer flow exchange) dimensionless conductance. The paper investigates the factors that influence the value of this new conductance. Among these factors are (1) the wetted perimeter of the cross-section, (2) the degree of penetration of the cross-section, and (3) the shape of the cross-section. The study shows that these factors just listed are indeed ordered in their respective level of importance. In addition the study verifies that the analytical correct value of the coefficient is matched by finite difference simulation only if the grid system is sufficiently fine. Thus the use of the analytical value of the coefficient is an accurate and efficient alternative to ad hoc estimates for the coefficient typically used in finite difference and finite element methods. PMID:24010703
Radiometric versus geometric, linear, and nonlinear vignetting coefficient.
Duma, Virgil-Florin
2009-11-10
We analyze the vignetting phenomenon both for optical systems with objects placed at finite distances and for systems with objects at infinity. Four of the possible definitions of the vignetting coefficient k, only two of them existing in the literature, are discussed. We propose two new definitions, i.e., a nonlinear geometric coefficient that is, in part, an analytical model of the vignetting characterization using optical software and a radiometric vignetting coefficient. The object space of each type of optical systems is studied first, defining its characteristic light circles and cones. Several simplifying assumptions are made for each of the two cases considered to derive analytical equations of the vignetting coefficient and thus to determine the best definition to be used. A geometric vignetting coefficient with two expressions, a linear classical and easy-to-use one and a nonlinear, that we propose for both types of systems is obtained. This nonlinear geometric vignetting coefficient proves to be more adequate in modeling the phenomenon, but it does not entirely fit the physical reality. We finally demonstrate that the radiometric vignetting coefficient we define and derive as a view factor for both types of optical systems is the most appropriate one. The half vignetting level, necessary in most optical design procedures to obtain a satisfactory illumination level in the image plane, is also discussed. PMID:19904336
Kappa coefficient: a popular measure of rater agreement
TANG, Wan; HU, Jun; ZHANG, Hui; WU, Pan; HE, Hua
2015-01-01
Summary In mental health and psychosocial studies it is often necessary to report on the between-rater agreement of measures used in the study. This paper discusses the concept of agreement, highlighting its fundamental difference from correlation. Several examples demonstrate how to compute the kappa coefficient – a popular statistic for measuring agreement – both by hand and by using statistical software packages such as SAS and SPSS. Real study data are used to illustrate how to use and interpret this coefficient in clinical research and practice. The article concludes with a discussion of the limitations of the coefficient. PMID:25852260
Maxwell boundary condition and velocity dependent accommodation coefficient
Struchtrup, Henning
2013-11-15
A modification of Maxwell's boundary condition for the Boltzmann equation is developed that allows to incorporate velocity dependent accommodation coefficients into the microscopic description. As a first example, it is suggested to consider the wall-particle interaction as a thermally activated process with three parameters. A simplified averaging procedure leads to jump and slip boundary conditions for hydrodynamics. Coefficients for velocity slip, temperature jump, and thermal transpiration flow are identified and compared with those resulting from the original Maxwell model and the Cercignani-Lampis model. An extension of the model leads to temperature dependent slip and jump coefficients.
Correlation of octanol/water solubility ratios and partition coefficients
Pinsuwan, S.; Li, A.; Yalkowsky, S.H.
1995-05-01
The partition coefficient between octanol and water in an important physicochemical parameter for characterizing the lipophilicity or hydrophobicity of a compound and it is used in many fields, especially in the environmental and pharmaceutical sciences. The octanol/water solubility ratio (S{sub o}/S{sub W}) was found to be highly correlated with the octanol/water partition coefficient (K{sub ow}) of 82 pharmaceutically and environmentally relevant compounds. The solubility ratio gives comparable estimates to that of the group contribution (log P(calcd)) method for estimating the partition coefficient of the compounds used in this study.
Kubo Formulas for Second-Order Hydrodynamic Coefficients
Moore, Guy D.; Sohrabi, Kiyoumars A.
2011-03-25
At second order in gradients, conformal relativistic hydrodynamics depends on the viscosity {eta} and on five additional ''second-order'' hydrodynamical coefficients {tau}{sub {Pi}}, {kappa}, {lambda}{sub 1}, {lambda}{sub 2}, and {lambda}{sub 3}. We derive Kubo relations for these coefficients, relating them to equilibrium, fully retarded three-point correlation functions of the stress tensor. We show that the coefficient {lambda}{sub 3} can be evaluated directly by Euclidean means and does not in general vanish.
Prediction of Aerodynamic Coefficients using Neural Networks for Sparse Data
NASA Technical Reports Server (NTRS)
Rajkumar, T.; Bardina, Jorge; Clancy, Daniel (Technical Monitor)
2002-01-01
Basic aerodynamic coefficients are modeled as functions of angles of attack and sideslip with vehicle lateral symmetry and compressibility effects. Most of the aerodynamic parameters can be well-fitted using polynomial functions. In this paper a fast, reliable way of predicting aerodynamic coefficients is produced using a neural network. The training data for the neural network is derived from wind tunnel test and numerical simulations. The coefficients of lift, drag, pitching moment are expressed as a function of alpha (angle of attack) and Mach number. The results produced from preliminary neural network analysis are very good.
Orientation and velocity dependence of the nonequilibrium partition coefficient
NASA Technical Reports Server (NTRS)
Beatty, K. M.; Jackson, K. A.
1995-01-01
Monte Carlo simulations based on a Spin-1 Ising Model for binary alloys have been used to investigate the non-equilibrium partition coefficient (k(sub neq)) as a function of solid-liquid interface velocity and orientation. In simulations of Si with a second component k(sub neq) is greater in the [111] direction than the [100] direction in agreement with experimental results reported by Azlz et al. The simulated partition coefficient scales with the square of the step velocity divided by the diffusion coefficient of the secondary component in the liquid.
Combined diffusion coefficients for a mixture of three ionized gases
NASA Astrophysics Data System (ADS)
Zhang, X. N.; Murphy, A. B.; Li, H. P.; Xia, W. D.
2014-12-01
The combined diffusion coefficient method has been demonstrated to greatly simplify the treatment of diffusion in the modelling of thermal plasmas in gas mixtures without loss of accuracy. In this paper, an extension of this method to allow treatment of diffusion of a three-gas mixture has been achieved, provided that the gases are homonuclear and do not react with each other, and satisfy local chemical equilibrium. Formulas for the combined diffusion coefficients are presented, and combined diffusion coefficients for different mixtures of helium, argon and carbon at temperatures up to 30 000 K and at atmosphere pressure are calculated as an example.
Kappa coefficient: a popular measure of rater agreement.
Tang, Wan; Hu, Jun; Zhang, Hui; Wu, Pan; He, Hua
2015-02-25
In mental health and psychosocial studies it is often necessary to report on the between-rater agreement of measures used in the study. This paper discusses the concept of agreement, highlighting its fundamental difference from correlation. Several examples demonstrate how to compute the kappa coefficient - a popular statistic for measuring agreement - both by hand and by using statistical software packages such as SAS and SPSS. Real study data are used to illustrate how to use and interpret this coefficient in clinical research and practice. The article concludes with a discussion of the limitations of the coefficient. PMID:25852260
Ionization coefficients for argon in a micro-discharge
NASA Astrophysics Data System (ADS)
Kuschel, Thomas; Stefanović, Ilija; Malović, Gordana; Marić, Dragana; Petrović, Zoran Lj
2013-08-01
Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges.
Drag and lift coefficients evolution of a Savonius rotor
NASA Astrophysics Data System (ADS)
Chauvin, A.; Benghrib, D.
1989-10-01
The lift and drag coefficients of the rotating Savonius wind machine are determined from the pressure difference measured between the upper plane and the lower plane of a blade. Pressure measurements have been performed for two sets of experiments; the first one for U ∞ = 10 m/s and the second one for U ∞ = 12.5 m/s. In each case it is to be noted that a negative lift effect is present for low values of the tip speed ratio λ. The lift coefficient becomes positive when λ increases. The drag coefficient is of course always negative.
ERIC Educational Resources Information Center
Padilla, Miguel A.; Divers, Jasmin
2016-01-01
Coefficient omega and alpha are both measures of the composite reliability for a set of items. Unlike coefficient alpha, coefficient omega remains unbiased with congeneric items with uncorrelated errors. Despite this ability, coefficient omega is not as widely used and cited in the literature as coefficient alpha. Reasons for coefficient omega's…
Rate coefficients for N2(+)(v) dissociative recombination
NASA Astrophysics Data System (ADS)
Bates, D. R.; Mitchell, J. B. A.
1991-09-01
The data of Zipf (1980) on N2(+)(v) dissociative recombination are analyzed taking into account the fact that there is coupling due to reversible symmetrical resonance charge transfer, N2(+)(v) + N2(0) yields N2(+)(0) + N2(v). The vibrational deactivation in N2(+)(v)-Ne collisions is also considered. A reported experimental value of the vibrational deactivation coefficient is found to be much higher than can be reconciled with the results of Zipf and it is therefore rejected. The analysis shows that the recombination coefficient for N2(+)(0) is about 2.6 x 10 exp-7 cu cm/s at 300 K and that recombination coefficients for N2(+)(1) and N2(+)(2) are substantially smaller. It is concluded that these coefficients conflict with the dissociative recombination cross section vs energy curve obtained by the merged beam method.
Measurement of heat transfer coefficients by nuclear magnetic resonance.
Gultekin, David H; Gore, John C
2008-11-01
We demonstrate an experimental method for the measurement of heat transfer coefficient for a fluid system by magnetic resonance imaging. In this method, the temporal variation of thermally induced nuclear shielding is monitored and the average heat transfer coefficient is measured as a function of fluid velocity. We examine the cases of natural convection and forced convection at fluid velocity up to 0.8 m s(-1). These cases correspond to low dimensionless Biot (Bi) number where the heat transfer is limited by thermal convection. We demonstrate the NMR method for two simple geometries, a cylinder and a sphere, to experimentally determine the heat transfer coefficient (h) in two NMR imaging and spectroscopy systems through measuring three NMR parameters, the chemical shift, magnetization and spin self diffusion coefficient. PMID:18524523
Effect of applied mechanical stress on absorption coefficient of compounds
Gupta, Manoj Kumar; Singh, Gurinderjeet; Dhaliwal, A. S.; Kahlon, K. S.
2015-08-28
The absorption coefficient of given materials is the parameter required for the basic information. The measurement of absorption coefficient of compounds Al{sub 2}O{sub 3}, CaCO{sub 3}, ZnO{sub 2}, SmO{sub 2} and PbO has been taken at different incident photon energies 26, 59.54, 112, 1173, 1332keV. The studies involve the measurements of absorption coefficient of the self supporting samples prepared under different mechanical stress. This mechanical stress is render in terms of pressure up to 0-6 ton by using hydraulic press. Measurements shows that absorption coefficient of a material is directly proportional to applied mechanical stress on it up to some extent then become independent. Experimentally measured results are in fairly good agreement with in theoretical values obtained from WinXCOM.
Determination of Catalytic Coefficient for a First-Order Reaction
ERIC Educational Resources Information Center
Fraga, E. R.; And Others
1975-01-01
Describes an undergraduate physical chemistry experiment in which the acid catalyzed hydrolysis of sucrose is used to determine the catalytic coefficient of the hydronium ion, the catalyst in this reaction. (MLH)
A database of selected transport coefficients for combustion studies
Cloutman, L.D.
1993-08-01
COYOTE and similar combustion programs based on the multicomponent Navier-Stokes equations require the mixture viscosity, thermal conductivity, and species transport coefficients as input. This report documents a significant improvement to the calculation of these molecular transport coefficients in COYOTE and provides a self-contained and easy-to-use source of such data in a format suitable for use by such programs. We present the data for various species in two forms. The first is a simple functional fit to the transport coefficients. The second is the use of tabulated Lennard-Jones parameters in simple theoretical expressions for the gas-phase transport coefficients. Tables are given for a number of chemical species.
Determination of thermal diffusion coefficient of nanofluid: Fullerene-toluene
NASA Astrophysics Data System (ADS)
Martin, Alain; Bou-Ali, M. Mounir
2011-05-01
Thermodiffusion coefficient at fullerene mass concentrations of 0.05%, 0.1%, 0.15%, and 0.2% was established for pure fullerene (C 60) diluted in toluene solutions. For this, the thermogravitational technique has been used in planar configuration with 4 extraction points. The determination of the concentration distribution along the column in steady state is determined by the method of analysis based on density measurements. In order to determine the thermal diffusion coefficient all thermophysical properties such as density, viscosity, thermal expansion coefficient and mass expansion coefficients were determined. All these studies coincide with the importance of the knowledge of the thermophysics and transport properties of the nanofluids to develop new applications and to optimize the existing ones.
Gamma ray attenuation coefficient measurement for neutron-absorbent materials
NASA Astrophysics Data System (ADS)
Jalali, Majid; Mohammadi, Ali
2008-05-01
The compounds Na 2B 4O 7, H 3BO 3, CdCl 2 and NaCl and their solutions attenuate gamma rays in addition to neutron absorption. These compounds are widely used in the shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to the four compounds aforementioned, in energies 662, 778.9, 867.38, 964.1, 1085.9, 1173, 1212.9, 1299.1,1332 and 1408 keV, have been determined by the γ rays transmission method in a good geometry setup; also, these coefficients were calculated by MCNP code. A comparison between experiments, simulations and Xcom code has shown that the study has potential application for determining the attenuation coefficient of various compound materials. Experiment and computation show that H 3BO 3 with the lowest average Z has the highest gamma ray attenuation coefficient among the aforementioned compounds.
Wind heat transfer coefficient in solar collectors in outdoor conditions
Kumar, Suresh; Mullick, S.C.
2010-06-15
Knowledge of wind heat transfer coefficient, h{sub w}, is required for estimation of upward losses from the outer surface of flat plate solar collectors/solar cookers. In present study, an attempt has been made to estimate the wind induced convective heat transfer coefficient by employing unglazed test plate (of size about 0.9 m square) in outdoor conditions. Experiments, for measurement of h{sub w}, have been conducted on rooftop of a building in the Institute campus in summer season for 2 years. The estimated wind heat transfer coefficient has been correlated against wind speed by linear regression and power regression. Experimental values of wind heat transfer coefficient estimated in present work have been compared with studies of other researchers after normalizing for plate length. (author)
Effect of applied mechanical stress on absorption coefficient of compounds
NASA Astrophysics Data System (ADS)
Gupta, Manoj Kumar; Singh, Gurinderjeet; Dhaliwal, A. S.; Kahlon, K. S.
2015-08-01
The absorption coefficient of given materials is the parameter required for the basic information. The measurement of absorption coefficient of compounds Al2O3, CaCO3, ZnO2, SmO2 and PbO has been taken at different incident photon energies 26, 59.54, 112, 1173, 1332keV. The studies involve the measurements of absorption coefficient of the self supporting samples prepared under different mechanical stress. This mechanical stress is render in terms of pressure up to 0-6 ton by using hydraulic press. Measurements shows that absorption coefficient of a material is directly proportional to applied mechanical stress on it up to some extent then become independent. Experimentally measured results are in fairly good agreement with in theoretical values obtained from WinXCOM.
How To Prepare Materials With a Desired Refraction Coefficient?
Ramm, A. G.
2010-05-21
In this talk a method is described for preparing materials with a desired refraction coefficient. The method consists of embedding into a material with known refraction coefficient many small particles of size a. The number of particles per unit volume around any point is prescribed, the distance between neighboring particles is O(a{sup (2-kappa/3)}) as a->0, 0
An instrumental variable random-coefficients model for binary outcomes
Chesher, Andrew; Rosen, Adam M
2014-01-01
In this paper, we study a random-coefficients model for a binary outcome. We allow for the possibility that some or even all of the explanatory variables are arbitrarily correlated with the random coefficients, thus permitting endogeneity. We assume the existence of observed instrumental variables Z that are jointly independent with the random coefficients, although we place no structure on the joint determination of the endogenous variable X and instruments Z, as would be required for a control function approach. The model fits within the spectrum of generalized instrumental variable models, and we thus apply identification results from our previous studies of such models to the present context, demonstrating their use. Specifically, we characterize the identified set for the distribution of random coefficients in the binary response model with endogeneity via a collection of conditional moment inequalities, and we investigate the structure of these sets by way of numerical illustration. PMID:25798048
A visual detection model for DCT coefficient quantization
NASA Technical Reports Server (NTRS)
Ahumada, Albert J., Jr.; Peterson, Heidi A.
1993-01-01
The discrete cosine transform (DCT) is widely used in image compression, and is part of the JPEG and MPEG compression standards. The degree of compression, and the amount of distortion in the decompressed image are determined by the quantization of the transform coefficients. The standards do not specify how the DCT coefficients should be quantized. Our approach is to set the quantization level for each coefficient so that the quantization error is at the threshold of visibility. Here we combine results from our previous work to form our current best detection model for DCT coefficient quantization noise. This model predicts sensitivity as a function of display parameters, enabling quantization matrices to be designed for display situations varying in luminance, veiling light, and spatial frequency related conditions (pixel size, viewing distance, and aspect ratio). It also allows arbitrary color space directions for the representation of color.
A dynamic model for the Lagrangian stochastic dispersion coefficient
Pesmazoglou, I.; Navarro-Martinez, S.; Kempf, A. M.
2013-12-15
A stochastic sub-grid model is often used to accurately represent particle dispersion in turbulent flows using large eddy simulations. Models of this type have a free parameter, the dispersion coefficient, which is not universal and is strongly grid-dependent. In the present paper, a dynamic model for the evaluation of the coefficient is proposed and validated in decaying homogeneous isotropic turbulence. The grid dependence of the static coefficient is investigated in a turbulent mixing layer and compared to the dynamic model. The dynamic model accurately predicts dispersion statistics and resolves the grid-dependence. Dispersion statistics of the dynamically calculated constant are more accurate than any static coefficient choice for a number of grid spacings. Furthermore, the dynamic model produces less numerical artefacts than a static model and exhibits smaller sensitivity in the results predicted for different particle relaxation times.
Intermittent-flow coefficients of a poppet valve
NASA Technical Reports Server (NTRS)
Waldron, C D
1939-01-01
Flow coefficients were determined for the inlet valve of a modern air-cooled cylinder during operation of the valve. The cylinder head with valves was mounted on a large tank that could be evacuated. Operating the valve with a rotating cam allowed air to flow through the valve into the evacuated tank. The change of pressure in the tank was a measure of the amount of air flowing though the valve in a given number of cycles. The flow coefficients were determined from the pressure across the valve, the quantity of air flowing, and the valve-lift curve. Coefficients were measured with lifts of 0.1 to 0.6 inch and speeds of 130 to 1,200 r.p.m. The results obtained with intermittent flow were compared with the results of tests made with steady flow through this cylinder head. This comparison indicated that steady-flow coefficients can be used for intermittent flow.
Seal assembly for materials with different coefficients of thermal expansion
Minford, Eric
2009-09-01
Seal assembly comprising (a) two or more seal elements, each element having having a coefficient of thermal expansion; and (b) a clamping element having a first segment, a second segment, and a connecting segment between and attached to the first and second segments, wherein the two or more seal elements are disposed between the first and second segments of the clamping element. The connecting segment has a central portion extending between the first segment of the clamping element and the second segment of the clamping element, and the connecting segment is made of a material having a coefficient of thermal expansion. The coefficient of thermal expansion of the material of the connecting segment is intermediate the largest and smallest of the coefficients of thermal expansion of the materials of the two or more seal elements.
A New Adaptive Image Denoising Method Based on Neighboring Coefficients
NASA Astrophysics Data System (ADS)
Biswas, Mantosh; Om, Hari
2016-03-01
Many good techniques have been discussed for image denoising that include NeighShrink, improved adaptive wavelet denoising method based on neighboring coefficients (IAWDMBNC), improved wavelet shrinkage technique for image denoising (IWST), local adaptive wiener filter (LAWF), wavelet packet thresholding using median and wiener filters (WPTMWF), adaptive image denoising method based on thresholding (AIDMT). These techniques are based on local statistical description of the neighboring coefficients in a window. These methods however do not give good quality of the images since they cannot modify and remove too many small wavelet coefficients simultaneously due to the threshold. In this paper, a new image denoising method is proposed that shrinks the noisy coefficients using an adaptive threshold. Our method overcomes these drawbacks and it has better performance than the NeighShrink, IAWDMBNC, IWST, LAWF, WPTMWF, and AIDMT denoising methods.
Virial coefficients and demixing in the Asakura-Oosawa model.
López de Haro, Mariano; Tejero, Carlos F; Santos, Andrés; Yuste, Santos B; Fiumara, Giacomo; Saija, Franz
2015-01-01
The problem of demixing in the Asakura-Oosawa colloid-polymer model is considered. The critical constants are computed using truncated virial expansions up to fifth order. While the exact analytical results for the second and third virial coefficients are known for any size ratio, analytical results for the fourth virial coefficient are provided here, and fifth virial coefficients are obtained numerically for particular size ratios using standard Monte Carlo techniques. We have computed the critical constants by successively considering the truncated virial series up to the second, third, fourth, and fifth virial coefficients. The results for the critical colloid and (reservoir) polymer packing fractions are compared with those that follow from available Monte Carlo simulations in the grand canonical ensemble. Limitations and perspectives of this approach are pointed out. PMID:25573578
Correlation equation for the marine drag coefficient and wave steepness
NASA Astrophysics Data System (ADS)
Foreman, Richard J.; Emeis, Stefan
2012-09-01
This work questions, starting from dimensional considerations, the generality of the belief that the marine drag coefficient levels off with increasing wind speed. Dimensional analysis shows that the drag coefficient scales with the wave steepness as opposed to a wave-age scaling. A correlation equation is employed here that uses wave steepness scaling at low aspect ratios (inverse wave steepnesses) and a constant drag coefficient at high aspect ratios. Invoked in support of the correlation are measurements sourced from the literature and at the FINO1 platform in the North Sea. The correlation equation is then applied to measurements recorded from buoys during the passage of hurricanes Rita, Katrina (2005) and Ike (2008). Results show that the correlation equation anticipates the expected levelling off in deeper water, but a drag coefficient more consistent with a Charnock type relation is also possible in more shallower water. Some suggestions are made for proceeding with a higher-order analysis than that conducted here.
Using two coefficients modeling of nonsubsampled Shearlet transform for despeckling
NASA Astrophysics Data System (ADS)
Jafari, Saeed; Ghofrani, Sedigheh
2016-01-01
Synthetic aperture radar (SAR) images are inherently affected by multiplicative speckle noise. Two approaches based on modeling the nonsubsampled Shearlet transform (NSST) coefficients are presented. Two-sided generalized Gamma distribution and normal inverse Gaussian probability density function have been used to model the statistics of NSST coefficients. Bayesian maximum a posteriori estimator is applied to the corrupted NSST coefficients in order to estimate the noise-free NSST coefficients. Finally, experimental results, according to objective and subjective criteria, carried out on both artificially speckled images and the true SAR images, demonstrate that the proposed methods outperform other state of art references via two points of view, speckle noise reduction and image quality preservation.
Calculation of coupling coefficients for equations of multipoint kinetics
NASA Astrophysics Data System (ADS)
Ioannisian, M. V.
2013-12-01
The multipoint kinetics equations for fission reaction rate are developed. The algorithm for computation of coupling coefficients is implemented within the MCU-5 code. Results from approbation of the method using the model problem and experimental data are presented.
[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
Temperature dependence of the Soret coefficient of ionic colloids
NASA Astrophysics Data System (ADS)
Sehnem, A. L.; Figueiredo Neto, A. M.; Aquino, R.; Campos, A. F. C.; Tourinho, F. A.; Depeyrot, J.
2015-10-01
The temperature dependence of the Soret coefficient ST(T ) in electrostatically charged magnetic colloids is investigated. Two different ferrofluids, with different particles' mean dimensions, are studied. In both cases we obtain a thermophilic behavior of the Soret effect. The temperature dependence of the Soret coefficient is described assuming that the nanoparticles migrate along the ionic thermoelectric field created by the thermal gradient. A model based on the contributions from the thermoelectrophoresis and variation of the double-layer energy, without fitting parameters, is used to describe the experimental results of the colloid with the bigger particles. To do so, independent measurements of the ζ potential, mass diffusion coefficient, and Seebeck coefficient are performed. The agreement of the theory and the experimental results is rather good. In the case of the ferrofluid with smaller particles, it is not possible to get experimentally reliable values of the ζ potential and the model described is used to evaluate this parameter and its temperature dependence.
Calculation of Thermal Conductivity Coefficients for Magnetized Neutron Star
NASA Astrophysics Data System (ADS)
Glushikhina, M. V.; Bisnovatyi-Kogan, G. S.
2015-01-01
The coefficients that determine the electron heat transfer and diffusion in the crust of neutron stars are calculated on the basis of a solution of the Boltzmann equation with allowance for degeneracy.
Constraining the Drag Coefficients of Meteors in Dark Flight
NASA Technical Reports Server (NTRS)
Carter, R. T.; Jandir, P. S.; Kress, M. E.
2011-01-01
Based on data in the aeronautics literature, we have derived functions for the drag coefficients of spheres and cubes as a function of Mach number. Experiments have shown that spheres and cubes exhibit an abrupt factor-of-two decrease in the drag coefficient as the object slows through the transonic regime. Irregularly shaped objects such as meteorites likely exhibit a similar trend. These functions are implemented in an otherwise simple projectile motion model, which is applicable to the non-ablative dark flight of meteors (speeds less than .+3 km/s). We demonstrate how these functions may be used as upper and lower limits on the drag coefficient of meteors whose shape is unknown. A Mach-dependent drag coefficient is potentially important in other planetary and astrophysical situations, for instance, in the core accretion scenario for giant planet formation.
Transfer having a coupling coefficient higher than its active material
NASA Technical Reports Server (NTRS)
Lesieutre, George A. (Inventor); Davis, Christopher L. (Inventor)
2001-01-01
A coupling coefficient is a measure of the effectiveness with which a shape-changing material (or a device employing such a material) converts the energy in an imposed signal to useful mechanical energy. Device coupling coefficients are properties of the device and, although related to the material coupling coefficients, are generally different from them. This invention describes a class of devices wherein the apparent coupling coefficient can, in principle, approach 1.0, corresponding to perfect electromechanical energy conversion. The key feature of this class of devices is the use of destabilizing mechanical pre-loads to counter inherent stiffness. The approach is illustrated for piezoelectric and thermoelectrically actuated devices. The invention provides a way to simultaneously increase both displacement and force, distinguishing it from alternatives such as motion amplification, and allows transducer designers to achieve substantial performance gains for actuator and sensor devices.
System to Measure Thermal Conductivity and Seebeck Coefficient for Thermoelectrics
NASA Technical Reports Server (NTRS)
Kim, Hyun-Jung; Skuza, Jonathan R.; Park, Yeonjoon; King, Glen C.; Choi, Sang H.; Nagavalli, Anita
2012-01-01
The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at elevated temperatures. This has led to the implementation of nonstandardized practices that have further complicated the confirmation of reported high ZT materials. The major objective of the procedure described is for the simultaneous measurement of the Seebeck coefficient and thermal diffusivity within a given temperature range. These thermoelectric measurements must be precise, accurate, and reproducible to ensure meaningful interlaboratory comparison of data. The custom-built thermal characterization system described in this NASA-TM is specifically designed to measure the inplane thermal diffusivity, and the Seebeck coefficient for materials in the ranging from 73 K through 373 K.
Abundance coefficients, a new method for measuring microorganism relative abundance
Forester, R.M.
1977-01-01
A new method of measuring the relative abundance of microorganisms by using a set of interrelated coefficients, termed 'abundance coefficients' or 'AC', is proposed. These coefficients provide a means of recording abundance for geometric density categories, and each density measurement represents an approximation of the Poisson parameter ??t. The AC is the natural logarithm of a 'characteristic value,' which is a particular number for each geometric density category. The 'characteristic values' are based upon a probabilistic error statement derived from the Poisson formula, and they present evidence for separation of the geometric category boundaries by e = 2.71828. The proposed AC provide a means for recording species abundance in a manner suitable for arithmetic manipulation, for population structure studies, and for the determination of practical limits for defining the presence or absence of a species. Further, these coefficients provide for both intrasample and intersample abundance comparisons. ?? 1977 Plenum Publishing Corporation.
Evolutionary dynamics of a system with periodic coefficients
NASA Astrophysics Data System (ADS)
Rand, Richard H.; Yazhbin, Max; Rand, David G.
2011-10-01
We investigate a problem in evolutionary game theory based on replicator equations with periodic coefficients. This approach to evolution combines classical game theory with differential equations. The RPS (Rock-Paper-Scissors) system studied has application to the population biology of lizards and to bacterial dynamics. The presence of periodic coefficients models variations in the environment due to seasonal effects and results in parametric excitation which is studied through the use of perturbation series and numerical integration.
Characterization of the effective electrostriction coefficients in ferroelectric thin films
Kholkin, A. L.; Akdogan, E. K.; Safari, A.; Chauvy, P.-F.; Setter, N.
2001-06-15
Electromechanical properties of a number of ferroelectric films including PbZr{sub x}Ti{sub 1{minus}x}O{sub 3}(PZT), 0.9PbMg{sub 1/3}Nb{sub 2/3}O{sub 3}{endash}0.1PbTiO{sub 3}(PMN-PT), and SrBi{sub 2}Ta{sub 2}O{sub 9}(SBT) are investigated using laser interferometry combined with conventional dielectric measurements. Effective electrostriction coefficients of the films, Q{sub eff}, are determined using a linearized electrostriction equation that couples longitudinal piezoelectric coefficient, d{sub 33}, with the polarization and dielectric constant. It is shown that, in PZT films, electrostriction coefficients slightly increase with applied electric field, reflecting the weak contribution of non-180{degree} domains to piezoelectric properties. In contrast, in PMN-PT and SBT films electrostriction coefficients are field independent, indicating the intrinsic nature of the piezoelectric response. The experimental values of Q{sub eff} are significantly smaller than those of corresponding bulk materials due to substrate clamping and possible size effects. Electrostriction coefficients of PZT layers are shown to depend strongly on the composition and preferred orientation of the grains. In particular, Q{sub eff} of (100) textured rhombohedral films (x=0.7) is significantly greater than that of (111) layers. Thus large anisotropy of the electrostrictive coefficients is responsible for recently observed large piezoelectric coefficients of (100) textured PZT films. Effective electrostriction coefficients obtained by laser interferometry allow evaluation of the electromechanical properties of ferroelectric films based solely on the dielectric parameters and thus are very useful in the design and fabrication of microsensors and microactuators. {copyright} 2001 American Institute of Physics.
Uranium plasma emission coefficient in the visible and near UV.
NASA Technical Reports Server (NTRS)
Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.
1971-01-01
Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.
Wavelength dependence of aerosol extinction coefficient for stratospheric aerosols
NASA Technical Reports Server (NTRS)
Yue, Glenn K.
1986-01-01
A simple empirical formula for the wavelength dependence of the aerosol extinction coefficient is proposed. The relationship between the constants in the formula and the variable parameter in the aerosol size distribution is explicitly expressed. Good agreement is found between the extinction coefficients calculated from the proposed formula and that calculated from Mie theory. The proposed expression is shown to be better than the Angstroem formula commonly used by atmospheric scientists.
Analytic expressions for ULF wave radiation belt radial diffusion coefficients
Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K
2014-01-01
We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Key Points Analytic expressions for the radial diffusion coefficients are presented The coefficients do not dependent on energy or wave m value The electric field diffusion coefficient dominates over the magnetic PMID:26167440
Calculating rotordynamic coefficients of seals by finite-difference techniques
NASA Technical Reports Server (NTRS)
Dietzen, F. J.; Nordmann, R.
1987-01-01
For modelling the turbulent flow in a seal the Navier-Stokes equations in connection with a turbulence (kappa-epsilon) model are solved by a finite-difference method. A motion of the shaft round the centered position is assumed. After calculating the corresponding flow field and the pressure distribution, the rotor-dynamic coefficients of the seal can be determined. These coefficients are compared with results obtained by using the bulk flow theory of Childs and with experimental results.
The temperature variation of hydrogen diffusion coefficients in metal alloys
NASA Technical Reports Server (NTRS)
Danford, M. D.
1990-01-01
Hydrogen diffusion coefficients were measured as a function of temperature for a few metal alloys using an electrochemical evolution technique. Results from these measurements are compared to those obtained by the time-lag method. In all cases, diffusion coefficients obtained by the electrochemical method are larger than those by the time-lag method by an order of magnitude or more. These differences are attributed mainly to hydrogen trapping.
Influence of pixel geometry on the 1/f noise coefficient
NASA Astrophysics Data System (ADS)
Généreux, Francis; Paultre, Jacques-Edmond; Tremblay, Bruno; Provençal, Francis; Alain, Christine
2013-06-01
This paper presents a systematic study of the 1/f noise coefficient as a function of pixel geometry for microbolometer structures. Structures with various VOx widths, electrode gaps, electrode widths and via hole sizes were fabricated and characterized. The experimental results show that the 1/f noise coefficient is adversely affected by current non uniformity, in agreement with model predictions. Design parameters that significantly impact current non uniformity are identified and approaches to minimize their importance are proposed.
Unitarity cuts with massive propagators and algebraic expressions for coefficients
Britto, Ruth; Feng Bo
2007-05-15
In the first part of this paper, we extend the d-dimensional unitarity cut method of Anastasiou et al. to cases with massive propagators. We present formulas for integral reduction with which one can obtain coefficients of all pentagon, box, triangle and massive bubble integrals. In the second part of this paper, we present a detailed study of the phase space integration for unitarity cuts. We carry out spinor integration in generality and give algebraic expressions for coefficients, intended for automated evaluation.
Higher order matrix differential equations with singular coefficient matrices
Fragkoulis, V. C.; Kougioumtzoglou, I. A.; Pantelous, A. A.; Pirrotta, A.
2015-03-10
In this article, the class of higher order linear matrix differential equations with constant coefficient matrices and stochastic process terms is studied. The coefficient of the highest order is considered to be singular; thus, rendering the response determination of such systems in a straightforward manner a difficult task. In this regard, the notion of the generalized inverse of a singular matrix is used for determining response statistics. Further, an application relevant to engineering dynamics problems is included.
Laser Measurement Of Convective-Heat-Transfer Coefficient
NASA Technical Reports Server (NTRS)
Porro, A. Robert; Hingst, Warren R.; Chriss, Randall M.; Seablom, Kirk D.; Keith, Theo G., Jr.
1994-01-01
Coefficient of convective transfer of heat at spot on surface of wind-tunnel model computed from measurements acquired by developmental laser-induced-heat-flux technique. Enables non-intrusive measurements of convective-heat-transfer coefficients at many points across surfaces of models in complicated, three-dimensional, high-speed flows. Measurement spot scanned across surface of model. Apparatus includes argon-ion laser, attenuator/beam splitter electronic shutter infrared camera, and subsystem.
Black holes, information, and the universal coefficient theorem
NASA Astrophysics Data System (ADS)
Patrascu, Andrei T.
2016-07-01
General relativity is based on the diffeomorphism covariant formulation of the laws of physics while quantum mechanics is based on the principle of unitary evolution. In this article, I provide a possible answer to the black hole information paradox by means of homological algebra and pairings generated by the universal coefficient theorem. The unitarity of processes involving black holes is restored by the demanding invariance of the laws of physics to the change of coefficient structures in cohomology.
Experimental Excitation Rate Coefficients for Ne VIII Ions
NASA Astrophysics Data System (ADS)
Chang, C. C.; Greve, P.; Kolk, K.-H.; Kunze, H.-J.
1984-02-01
From the line emission of a pure neon plasma produced in a theta pinch discharge rate coefficients for the excitation of the n = 3 and 4 levels in Ne VIII ions are derived and compared with theoretical calculations and previous measurements. The general agreement between theory and all measurements is rather satisfactory for the excitation to the n = 3 levels, the measured rate coefficients to the 4p and 4d levels, however, being consistently too low.
Overall Heat and Mass Transfer Coefficient of Water Vapor Adsorption
NASA Astrophysics Data System (ADS)
Hamamoto, Yoshinori; Mori, Hideo; Godo, Masazumi; Miura, Kunio; Watanabe, Yutaka; Ishizawa, Toshihiko; Takatsuka, Takeshi
A fundamental investigation was performed to develop a compact and simple desiccant ventilation unit which is one of the main components of a novel energy saving air-conditioning system. Water vapor in the air is adsorbed and/or desorbed to be controlled the humidity of supply air through a unit of an adsorbent rotor. A numerical simulation helps to understand the phenomena of heat and mass transfer in the rotor block. Overall transfer coefficients were estimated by performing both experiment and calculation. It was examined that the transient overall equivalent heat and mass transfer coefficient was not constant. It seems that both film fluid and diffusion resistance govern the coefficients in the block, and the influence of air flow on the time averaged coefficients is estimated by a considering the laminar forced convection from a flat plate. There is little difference of the coefficient between adsorption and desorption process. The correlation and fitting parameters are presented for prediction of the overall heat and mass transfer coefficients. The estimation accuracy was improved.
Atmospheric Density Corrections Estimated from Fitted Drag Coefficients
NASA Astrophysics Data System (ADS)
McLaughlin, C. A.; Lechtenberg, T. F.; Mance, S. R.; Mehta, P.
2010-12-01
Fitted drag coefficients estimated using GEODYN, the NASA Goddard Space Flight Center Precision Orbit Determination and Geodetic Parameter Estimation Program, are used to create density corrections. The drag coefficients were estimated for Stella, Starlette and GFZ using satellite laser ranging (SLR) measurements; and for GEOSAT Follow-On (GFO) using SLR, Doppler, and altimeter crossover measurements. The data analyzed covers years ranging from 2000 to 2004 for Stella and Starlette, 2000 to 2002 and 2005 for GFO, and 1995 to 1997 for GFZ. The drag coefficient was estimated every eight hours. The drag coefficients over the course of a year show a consistent variation about the theoretical and yearly average values that primarily represents a semi-annual/seasonal error in the atmospheric density models used. The atmospheric density models examined were NRLMSISE-00 and MSIS-86. The annual structure of the major variations was consistent among all the satellites for a given year and consistent among all the years examined. The fitted drag coefficients can be converted into density corrections every eight hours along the orbit of the satellites. In addition, drag coefficients estimated more frequently can provide a higher frequency of density correction.
Attenuation Coefficient Estimation of the Healthy Human Thyroid In Vivo
NASA Astrophysics Data System (ADS)
Rouyer, J.; Cueva, T.; Portal, A.; Yamamoto, T.; Lavarello, R.
Previous studies have demonstrated that attenuation coefficients can be useful towards characterizing thyroid tissues. In this work, ultrasonic attenuation coefficients were estimated from healthy human thyroids in vivo using a clinical scanner. The selected subjects were five young, healthy volunteers (age: 26 ± 6 years old, gender: three females, two males) with no reported history of thyroid diseases, no palpable thyroid nodules, no smoking habits, and body mass index less than 30 kg/m2. Echographic examinations were conducted by a trained sonographer using a SonixTouch system (Ultrasonix Medical Corporation, Richmond, BC) equipped with an L14-5 linear transducer array (nominal center frequency of 10 MHz, transducer footprint of 3.8 cm). Radiofrequency data corresponding to the collected echographic images in both transverse and longitudinal views were digitized at a sampling rate of 40 MHz and processed with Matlab codes (MathWorks, Natick, MA) to estimate attenuation coefficients using the spectral log difference method. The estimation was performed using an analysis bandwidth spanning from 4.0 to 9.0 MHz. The average value of the estimated ultrasonic attenuation coefficients was equal to 1.34 ± 0.15 dB/(cm.MHz). The standard deviation of the estimated average attenuation coefficient across different volunteers suggests a non-negligible inter-subject variability in the ultrasonic attenuation coefficient of the human thyroid.
Identification of a positive-Seebeck-coefficient exohedral fullerene
NASA Astrophysics Data System (ADS)
Almutlaq, Nasser; Al-Galiby, Qusiy; Bailey, Steven; Lambert, Colin J.
2016-07-01
If fullerene-based thermoelectricity is to become a viable technology, then fullerenes exhibiting both positive and negative Seebeck coefficients are needed. C60 is known to have a negative Seebeck coefficient and therefore in this paper we address the challenge of identifying a positive-Seebeck-coefficient fullerene. We investigated the thermoelectric properties of single-molecule junctions of the exohedral fullerene C50Cl10 connected to gold electrodes and found that it indeed possesses a positive Seebeck coefficient. Furthermore, in common with C60, the Seebeck coefficient can be increased by placing more than one C50Cl10 in series. For a single C50Cl10, we find S = +8 μV K-1 and for two C50Cl10's in series we find S = +30 μV K-1. We also find that the C50Cl10 monomer and dimer have power factors of 0.5 × 10-5 W m-1 K-2 and 6.0 × 10-5 W m-1 K-2 respectively. These results demonstrate that exohedral fullerenes provide a new class of thermoelectric materials with desirable properties, which complement those of all-carbon fullerenes, thereby enabling the boosting of the thermovoltage in all-fullerene tandem structures.If fullerene-based thermoelectricity is to become a viable technology, then fullerenes exhibiting both positive and negative Seebeck coefficients are needed. C60 is known to have a negative Seebeck coefficient and therefore in this paper we address the challenge of identifying a positive-Seebeck-coefficient fullerene. We investigated the thermoelectric properties of single-molecule junctions of the exohedral fullerene C50Cl10 connected to gold electrodes and found that it indeed possesses a positive Seebeck coefficient. Furthermore, in common with C60, the Seebeck coefficient can be increased by placing more than one C50Cl10 in series. For a single C50Cl10, we find S = +8 μV K-1 and for two C50Cl10's in series we find S = +30 μV K-1. We also find that the C50Cl10 monomer and dimer have power factors of 0.5 × 10-5 W m-1 K-2 and 6.0 × 10-5 W m-1
Generalized transport coefficients for inelastic Maxwell mixtures under shear flow.
Garzó, Vicente; Trizac, Emmanuel
2015-11-01
The Boltzmann equation framework for inelastic Maxwell models is considered to determine the transport coefficients associated with the mass, momentum, and heat fluxes of a granular binary mixture in spatially inhomogeneous states close to the simple shear flow. The Boltzmann equation is solved by means of a Chapman-Enskog-type expansion around the (local) shear flow distributions f(r)(0) for each species that retain all the hydrodynamic orders in the shear rate. Due to the anisotropy induced by the shear flow, tensorial quantities are required to describe the transport processes instead of the conventional scalar coefficients. These tensors are given in terms of the solutions of a set of coupled equations, which can be analytically solved as functions of the shear rate a, the coefficients of restitution α(rs), and the parameters of the mixture (masses, diameters, and composition). Since the reference distribution functions f(r)(0) apply for arbitrary values of the shear rate and are not restricted to weak dissipation, the corresponding generalized coefficients turn out to be nonlinear functions of both a and α(rs). The dependence of the relevant elements of the three diffusion tensors on both the shear rate and dissipation is illustrated in the tracer limit case, the results showing that the deviation of the generalized transport coefficients from their forms for vanishing shear rates is in general significant. A comparison with the previous results obtained analytically for inelastic hard spheres by using Grad's moment method is carried out, showing a good agreement over a wide range of values for the coefficients of restitution. Finally, as an application of the theoretical expressions derived here for the transport coefficients, thermal diffusion segregation of an intruder immersed in a granular gas is also studied. PMID:26651684
Generalized transport coefficients for inelastic Maxwell mixtures under shear flow
NASA Astrophysics Data System (ADS)
Garzó, Vicente; Trizac, Emmanuel
2015-11-01
The Boltzmann equation framework for inelastic Maxwell models is considered to determine the transport coefficients associated with the mass, momentum, and heat fluxes of a granular binary mixture in spatially inhomogeneous states close to the simple shear flow. The Boltzmann equation is solved by means of a Chapman-Enskog-type expansion around the (local) shear flow distributions fr(0 ) for each species that retain all the hydrodynamic orders in the shear rate. Due to the anisotropy induced by the shear flow, tensorial quantities are required to describe the transport processes instead of the conventional scalar coefficients. These tensors are given in terms of the solutions of a set of coupled equations, which can be analytically solved as functions of the shear rate a , the coefficients of restitution αr s, and the parameters of the mixture (masses, diameters, and composition). Since the reference distribution functions fr(0 ) apply for arbitrary values of the shear rate and are not restricted to weak dissipation, the corresponding generalized coefficients turn out to be nonlinear functions of both a and αr s. The dependence of the relevant elements of the three diffusion tensors on both the shear rate and dissipation is illustrated in the tracer limit case, the results showing that the deviation of the generalized transport coefficients from their forms for vanishing shear rates is in general significant. A comparison with the previous results obtained analytically for inelastic hard spheres by using Grad's moment method is carried out, showing a good agreement over a wide range of values for the coefficients of restitution. Finally, as an application of the theoretical expressions derived here for the transport coefficients, thermal diffusion segregation of an intruder immersed in a granular gas is also studied.
Experimental determination of group flux control coefficients in metabolic networks
Simpson, T.W.; Shimizu, Hiroshi; Stephanopoulos, G.
1998-04-20
Grouping of reactions around key metabolite branch points can facilitate the study of metabolic control of complex metabolic networks. This top-down Metabolic Control Analysis is exemplified through the introduction of group control coefficients whose magnitudes provide a measure of the relative impact of each reaction group on the overall network flux, as well as on the overall network stability, following enzymatic amplification. In this article, the authors demonstrate the application of previously developed theory to the determination of group flux control coefficients. Experimental data for the changes in metabolic fluxes obtained in response to the introduction of six different environmental perturbations are used to determine the group flux control coefficients for three reaction groups formed around the phosphoenolpyruvate/pyruvate branch point. The consistency of the obtained group flux control coefficient estimates is systematically analyzed to ensure that all necessary conditions are satisfied. The magnitudes of the determined control coefficients suggest that the control of lysine production flux in Corynebacterium glutamicum cells at a growth base state resides within the lysine biosynthetic pathway that begins with the PEP/PYR carboxylation anaplorotic pathway.
Spatially Varying Coefficient Model for Neuroimaging Data with Jump Discontinuities
Zhu, Hongtu; Fan, Jianqing; Kong, Linglong
2014-01-01
Motivated by recent work on studying massive imaging data in various neuroimaging studies, we propose a novel spatially varying coefficient model (SVCM) to capture the varying association between imaging measures in a three-dimensional (3D) volume (or 2D surface) with a set of covariates. Two stylized features of neuorimaging data are the presence of multiple piecewise smooth regions with unknown edges and jumps and substantial spatial correlations. To specifically account for these two features, SVCM includes a measurement model with multiple varying coefficient functions, a jumping surface model for each varying coefficient function, and a functional principal component model. We develop a three-stage estimation procedure to simultaneously estimate the varying coefficient functions and the spatial correlations. The estimation procedure includes a fast multiscale adaptive estimation and testing procedure to independently estimate each varying coefficient function, while preserving its edges among different piecewise-smooth regions. We systematically investigate the asymptotic properties (e.g., consistency and asymptotic normality) of the multiscale adaptive parameter estimates. We also establish the uniform convergence rate of the estimated spatial covariance function and its associated eigenvalues and eigenfunctions. Our Monte Carlo simulation and real data analysis have confirmed the excellent performance of SVCM. PMID:25435598
ICRP dose coefficients: computational development and current status.
Bolch, W E; Petoussi-Henss, N; Paquet, F; Harrison, J
2016-06-01
Major current efforts within Committee 2 of the International Commission on Radiological Protection (ICRP) involve the development of dose coefficients for inhalation and ingestion of radionuclides, and those for exposure to environmental radiation fields. These efforts build upon changes in radiation and tissue weighting factors (Publication 103), radionuclide decay schemes (Publication 107), computational phantoms of the adult reference male and female (Publication 110), external dose coefficients for adult reference workers for idealised radiation fields (Publication 116), models of radionuclide intake (Publications 66, 100 and 130), and models of radionuclide systemic biokinetics (Publication 130). This paper will review the overall computational framework for both internal and external dose coefficients. For internal exposures, the work entails assessment of organ self-dose and cross-dose from monoenergetic particle emissions (specific absorbed fraction), absorbed dose per nuclear transformation (S value), time-integrated activity of the radionuclide in source tissues (inhalation, ingestion, and systemic biokinetic models), and their numerical combination to yield the organ equivalent dose or effective dose per activity inhaled or ingested. Various challenges are reviewed that were not included in the development of Publication 30 dose coefficients, which were based upon much more simplified biokinetic models and computational phantoms. For external exposures, the computations entail the characterisation of environmental radionuclide distributions, the transport of radiation particles through that environment, and the tracking of energy deposition to the organs of the exposed individual. Progress towards the development of dose coefficients to members of the general public (adolescents, children, infants and fetuses) are also reviewed. PMID:27048756
Theoretical approximations and experimental extinction coefficients of biopharmaceuticals.
Miranda-Hernández, Mariana P; Valle-González, Elba R; Ferreira-Gómez, David; Pérez, Néstor O; Flores-Ortiz, Luis F; Medina-Rivero, Emilio
2016-02-01
UV spectrophotometric measurement is a widely accepted and standardized routine analysis for quantitation of highly purified proteins; however, the reliability of the results strictly depends on the accuracy of the employed extinction coefficients. In this work, an experimental estimation of the differential refractive index (dn/dc), based on dry weight measurements, was performed in order to determine accurate extinction coefficients for four biotherapeutic proteins and one synthetic copolymer after separation in a size-exclusion ultra-performance liquid chromatograph coupled to an ultraviolet, multiangle light scattering and refractive index (SE-UPLC-UV-MALS-RI) multidetection system. The results showed small deviations with respect to theoretical values, calculated from the specific amino acid sequences, for all the studied immunoglobulins. Nevertheless, for proteins like etanercept and glatiramer acetate, several considerations, such as glycan content, partial specific volume, polarizability, and higher order structure, should be considered to properly calculate theoretical extinction coefficient values. Herein, these values were assessed with simple approximations. The precision of the experimentally obtained extinction coefficients, and its convergence towards the theoretical values, makes them useful for characterization and comparability exercises. Also, these values provide insight into the absorbance and scattering properties of the evaluated proteins. Overall, this methodology is capable of providing accurate extinction coefficients useful for development studies. PMID:26715251
Identifying Bearing Rotordynamic Coefficients using an Extended Kalman Filter
NASA Technical Reports Server (NTRS)
Miller, Bard A.; Howard, Samuel A.
2008-01-01
An Extended Kalman Filter is developed to estimate the linearized direct and indirect stiffness and damping force coefficients for bearings in rotor-dynamic applications from noisy measurements of the shaft displacement in response to imbalance and impact excitation. The bearing properties are modeled as stochastic random variables using a Gauss-Markov model. Noise terms are introduced into the system model to account for all of the estimation error, including modeling errors and uncertainties and the propagation of measurement errors into the parameter estimates. The system model contains two user-defined parameters that can be tuned to improve the filter s performance; these parameters correspond to the covariance of the system and measurement noise variables. The filter is also strongly influenced by the initial values of the states and the error covariance matrix. The filter is demonstrated using numerically simulated data for a rotor-bearing system with two identical bearings, which reduces the number of unknown linear dynamic coefficients to eight. The filter estimates for the direct damping coefficients and all four stiffness coefficients correlated well with actual values, whereas the estimates for the cross-coupled damping coefficients were the least accurate.
Identifying Bearing Rotodynamic Coefficients Using an Extended Kalman Filter
NASA Technical Reports Server (NTRS)
Miller, Brad A.; Howard, Samuel A.
2008-01-01
An Extended Kalman Filter is developed to estimate the linearized direct and indirect stiffness and damping force coefficients for bearings in rotor dynamic applications from noisy measurements of the shaft displacement in response to imbalance and impact excitation. The bearing properties are modeled as stochastic random variables using a Gauss-Markov model. Noise terms are introduced into the system model to account for all of the estimation error, including modeling errors and uncertainties and the propagation of measurement errors into the parameter estimates. The system model contains two user-defined parameters that can be tuned to improve the filter's performance; these parameters correspond to the covariance of the system and measurement noise variables. The filter is also strongly influenced by the initial values of the states and the error covariance matrix. The filter is demonstrated using numerically simulated data for a rotor bearing system with two identical bearings, which reduces the number of unknown linear dynamic coefficients to eight. The filter estimates for the direct damping coefficients and all four stiffness coefficients correlated well with actual values, whereas the estimates for the cross-coupled damping coefficients were the least accurate.
Viscosity Coefficient Curve Fits for Ionized Gas Species Grant Palmer
NASA Technical Reports Server (NTRS)
Palmer, Grant; Arnold, James O. (Technical Monitor)
2001-01-01
Viscosity coefficient curve fits for neutral gas species are available from many sources. Many do a good job of reproducing experimental and computational chemistry data. The curve fits are usually expressed as a function of temperature only. This is consistent with the governing equations used to derive an expression for the neutral species viscosity coefficient. Ionized species pose a more complicated problem. They are subject to electrostatic as well as intermolecular forces. The electrostatic forces are affected by a shielding phenomenon where electrons shield the electrostatic forces of positively charged ions beyond a certain distance. The viscosity coefficient for an ionized gas species is a function of both temperature and local electron number density. Currently available curve fits for ionized gas species, such as those presented by Gupta/Yos, are a function of temperature only. What they did was to assume an electron number density. The problem is that the electron number density they assumed was unrealistically high. The purpose of this paper is two-fold. First, the proper expression for determining the viscosity coefficient of an ionized species as a function of both temperature and electron number density will be presented. Then curve fit coefficients will be developed using the more realistic assumption of an equilibrium electron number density. The results will be compared against previous curve fits and against highly accurate computational chemistry data.
Experimental measurements of the diffusion coefficient of 212Pb.
Su, Y F; Newton, G J; Cheng, Y S; Yeh, H C
1989-03-01
Knowledge of the diffusion coefficient of Rn progeny is necessary for assessing the radiation exposure resulting from exposure to Rn and its progeny. The diffusion coefficient for 220Rn progeny was determined in ambient air by two independent methods, measuring deposition using a cylindrical tube or screens. A sampling train consisting of a diffusion tube and a screen-type diffusion battery was used for the experimental study. A range of flow rates and relative humidities was investigated. For 35% less than or equal to RH less than or equal to 85%, results from the two systems agree with each other. The diffusion coefficient of 212Pb was 0.036 +/- 0.002 cm2 s-1 and 0.037 +/- 0.004 cm2 s-1 for the tube and screen penetration methods, respectively. In low humidity air (RH less than 30%), a linear relationship between the diffusion coefficient of 212Pb and relative humidity was observed. The observed diffusion coefficient is strongly affected by the amount of material agglomerated onto the 212Pb atom. Further studies on the effects of trace gases and organics are required to fully understand the results. PMID:2537267
Experimental measurements of the diffusion coefficient of /sup 212/Pb
Su, Y.F.; Newton, G.J.; Cheng, Y.S.; Yeh, H.C.
1989-03-01
Knowledge of the diffusion coefficient of Rn progeny is necessary for assessing the radiation exposure resulting from exposure to Rn and its progeny. The diffusion coefficient for 220Rn progeny was determined in ambient air by two independent methods, measuring deposition using a cylindrical tube or screens. A sampling train consisting of a diffusion tube and a screen-type diffusion battery was used for the experimental study. A range of flow rates and relative humidities was investigated. For 35% less than or equal to RH less than or equal to 85%, results from the two systems agree with each other. The diffusion coefficient of 212Pb was 0.036 +/- 0.002 cm2 s-1 and 0.037 +/- 0.004 cm2 s-1 for the tube and screen penetration methods, respectively. In low humidity air (RH less than 30%), a linear relationship between the diffusion coefficient of 212Pb and relative humidity was observed. The observed diffusion coefficient is strongly affected by the amount of material agglomerated onto the 212Pb atom. Further studies on the effects of trace gases and organics are required to fully understand the results.
Identification of a positive-Seebeck-coefficient exohedral fullerene.
Almutlaq, Nasser; Al-Galiby, Qusiy; Bailey, Steven; Lambert, Colin J
2016-07-14
If fullerene-based thermoelectricity is to become a viable technology, then fullerenes exhibiting both positive and negative Seebeck coefficients are needed. C60 is known to have a negative Seebeck coefficient and therefore in this paper we address the challenge of identifying a positive-Seebeck-coefficient fullerene. We investigated the thermoelectric properties of single-molecule junctions of the exohedral fullerene C50Cl10 connected to gold electrodes and found that it indeed possesses a positive Seebeck coefficient. Furthermore, in common with C60, the Seebeck coefficient can be increased by placing more than one C50Cl10 in series. For a single C50Cl10, we find S = +8 μV K(-1) and for two C50Cl10's in series we find S = +30 μV K(-1). We also find that the C50Cl10 monomer and dimer have power factors of 0.5 × 10(-5) W m(-1) K(-2) and 6.0 × 10(-5) W m(-1) K(-2) respectively. These results demonstrate that exohedral fullerenes provide a new class of thermoelectric materials with desirable properties, which complement those of all-carbon fullerenes, thereby enabling the boosting of the thermovoltage in all-fullerene tandem structures. PMID:27357101
Statistical Study of Turbulence: Spectral Functions and Correlation Coefficients
NASA Technical Reports Server (NTRS)
Frenkiel, Francois N.
1958-01-01
In reading the publications on turbulence of different authors, one often runs the risk of confusing the various correlation coefficients and turbulence spectra. We have made a point of defining, by appropriate concepts, the differences which exist between these functions. Besides, we introduce in the symbols a few new characteristics of turbulence. In the first chapter, we study some relations between the correlation coefficients and the different turbulence spectra. Certain relations are given by means of demonstrations which could be called intuitive rather than mathematical. In this way we demonstrate that the correlation coefficients between the simultaneous turbulent velocities at two points are identical, whether studied in Lagrange's or in Euler's systems. We then consider new spectra of turbulence, obtained by study of the simultaneous velocities along a straight line of given direction. We determine some relations between these spectra and the correlation coefficients. Examining the relation between the spectrum of the turbulence measured at a fixed point and the longitudinal-correlation curve given by G. I. Taylor, we find that this equation is exact only when the coefficient is very small.
Incremental Aerodynamic Coefficient Database for the USA2
NASA Technical Reports Server (NTRS)
Richardson, Annie Catherine
2016-01-01
In March through May of 2016, a wind tunnel test was conducted by the Aerosciences Branch (EV33) to visually study the unsteady aerodynamic behavior over multiple transition geometries for the Universal Stage Adapter 2 (USA2) in the MSFC Aerodynamic Research Facility's Trisonic Wind Tunnel (TWT). The purpose of the test was to make a qualitative comparison of the transonic flow field in order to provide a recommended minimum transition radius for manufacturing. Additionally, 6 Degree of Freedom force and moment data for each configuration tested was acquired in order to determine the geometric effects on the longitudinal aerodynamic coefficients (Normal Force, Axial Force, and Pitching Moment). In order to make a quantitative comparison of the aerodynamic effects of the USA2 transition geometry, the aerodynamic coefficient data collected during the test was parsed and incorporated into a database for each USA2 configuration tested. An incremental aerodynamic coefficient database was then developed using the generated databases for each USA2 geometry as a function of Mach number and angle of attack. The final USA2 coefficient increments will be applied to the aerodynamic coefficients of the baseline geometry to adjust the Space Launch System (SLS) integrated launch vehicle force and moment database based on the transition geometry of the USA2.
LIMB-DARKENING COEFFICIENTS FOR ECLIPSING WHITE DWARFS
Gianninas, A.; Strickland, B. D.; Kilic, Mukremin; Bergeron, P. E-mail: benstrickland@ou.edu E-mail: bergeron@astro.umontreal.ca
2013-03-20
We present extensive calculations of linear and nonlinear limb-darkening coefficients as well as complete intensity profiles appropriate for modeling the light-curves of eclipsing white dwarfs. We compute limb-darkening coefficients in the Johnson-Kron-Cousins UBVRI photometric system as well as the Large Synoptic Survey Telescope (LSST) ugrizy system using the most up to date model atmospheres available. In all, we provide the coefficients for seven different limb-darkening laws. We describe the variations of these coefficients as a function of the atmospheric parameters, including the effects of convection at low effective temperatures. Finally, we discuss the importance of having readily available limb-darkening coefficients in the context of present and future photometric surveys like the LSST, Palomar Transient Factory, and the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS). The LSST, for example, may find {approx}10{sup 5} eclipsing white dwarfs. The limb-darkening calculations presented here will be an essential part of the detailed analysis of all of these systems.
Empirical evidence for site coefficients in building code provisions
Borcherdt, R.D.
2002-01-01
Site-response coefficients, Fa and Fv, used in U.S. building code provisions are based on empirical data for motions up to 0.1 g. For larger motions they are based on theoretical and laboratory results. The Northridge earthquake of 17 January 1994 provided a significant new set of empirical data up to 0.5 g. These data together with recent site characterizations based on shear-wave velocity measurements provide empirical estimates of the site coefficients at base accelerations up to 0.5 g for Site Classes C and D. These empirical estimates of Fa and Fnu; as well as their decrease with increasing base acceleration level are consistent at the 95 percent confidence level with those in present building code provisions, with the exception of estimates for Fa at levels of 0.1 and 0.2 g, which are less than the lower confidence bound by amounts up to 13 percent. The site-coefficient estimates are consistent at the 95 percent confidence level with those of several other investigators for base accelerations greater than 0.3 g. These consistencies and present code procedures indicate that changes in the site coefficients are not warranted. Empirical results for base accelerations greater than 0.2 g confirm the need for both a short- and a mid- or long-period site coefficient to characterize site response for purposes of estimating site-specific design spectra.
[Biodegradation Coefficients of Typical Pollutants in the Plain Rivers Network].
Feng, Shuai; Li, Xu-yongl; Deng, Jian-cai
2016-05-15
Biodegradation is a significant part of pollutant integrated degradation, the process rate of which is represented by the biodegradation coefficient. To investigate the biodegradation law of typical pollutants in the plain rivers network located in the upstream of the Lake Taihu, experiments were conducted in site in September 2015, one order kinetics model was used to measure the biodegradation coefficients for permanganate index, ammonia, total nitrogen and total phosphorus, and influencing factors of the biodegradation coefficients were also analyzed. The results showed that the biodegradation coefficients for permanganate index, ammonia, total nitrogen and total phosphorus were 0.008 3-0.126 4 d⁻¹, 0.002 1-0.213 8 d⁻¹, 0.002 1-0.090 5 d⁻¹ and 0.011 0- 0.152 8 d⁻¹, respectively. The influencing factors of the biodegradation coefficients for permanganate index were permanganate index and pH; those for ammonia were ammonia concentration and pH; those for total nitrogen were inorganic nitrogen concentration, total dissolved solid concentration and nitrite concentration; and those for total phosphorus were background concentration and pH. The research results were of important guiding significance for pollutants removal and ecological restoration of the plain rivers network located in the unstream of the Lake Taihu. PMID:27506025
Calculation of Diffusion Coefficients from Bounce Resonance with Magnetosonic Waves
NASA Astrophysics Data System (ADS)
Tao, X.; Li, X.; Lu, Q.; Dai, L.
2015-12-01
Theoretical bounce resonance diffusion coefficients for interactions between electrons and magnetosonic waves are calculated and validated using guiding-center test particle simulations. First, we compare the theoretical diffusion coefficients of Roberts and Schulz with test particle simulations and find perfect agreement. However, the theoretical diffusion coefficients of Roberts and Schulz assume waves to be present on the whole trajectories of particles; therefore, they are not directly applicable to magnetosonic waves, which are found to be confined to equatorial regions from observations. Second, we derive a new set of bounce-resonance diffusion coefficients, taking into consideration the equatorial confinement of magnetosonic waves. These new diffusion coefficients are also validated by test particle simulations. Using a previously published magnetosonic wave model, our results demonstrate that bounce-resonance diffusion mainly results in strong pitch angle scattering of energetic electrons even with a moderate wave amplitude of 50 pT. We conclude that bounce-resonance diffusion plays an important role in relativistic electron dynamics and should be incorporated into global radiation belt modeling.
Conformal anomaly c-coefficients of superconformal 6d theories
NASA Astrophysics Data System (ADS)
Beccaria, Matteo; Tseytlin, Arkady A.
2016-01-01
We propose general relations between the conformal anomaly and the chiral (R-symmetry and gravitational) anomaly coefficients in 6d (1, 0) superconformal theories. The suggested expressions for the three type B conformal anomaly c i -coefficients complement the expression for the type A anomaly a-coefficient found in arXiv:1506.03807. We check them on several examples — the standard (1, 0) hyper and tensor multiplets as well as some higher derivative short multiplets containing vector fields that generalize the super-conformal 6d vector multiplet discussed in arXiv:1506.08727. We also consider a family of higher derivative superconformal (2, 0) 6d multiplets associated to 7d multiplets in the KK spectrum of 11d supergravity compactified on S 4. In particular, we prove that (2,0) 6d conformal supergravity coupled to 26 tensor multiplets is free of all chiral and conformal anomalies. We discuss some interacting (1, 0) superconformal theories, predicting the c i -coefficients for the "E-string" theory on multiple M5-branes at E 8 9-brane and for the theory describing M5-branes at an orbifold singularity {C}^2/Γ . Finally, we elaborate on holographic computation of subleading corrections to conformal anomaly coefficients coming from R 2 + R 3 terms in 7d effective action, revisiting, in particular, the (2,0) theory case.
Rock shape, restitution coefficients and rockfall trajectory modelling
NASA Astrophysics Data System (ADS)
Glover, James; Christen, Marc; Bühler, Yves; Bartelt, Perry
2014-05-01
Restitution coefficients are used in rockfall trajectory modelling to describe the ratio between incident and rebound velocities during ground impact. They are central to the problem of rockfall hazard analysis as they link rock mass characteristics to terrain properties. Using laboratory experiments as a guide, we first show that restitution coefficients exhibit a wide range of scatter, although the material properties of the rock and ground are constant. This leads us to the conclusion that restitution coefficients are poor descriptors of rock-ground interaction. The primary problem is that "apparent" restitution coefficients are applied at the rock's centre-of-mass and do not account for rock shape. An accurate description of the rock-ground interaction requires the contact forces to be applied at the rock surface with consideration of the momentary rock position and spin. This leads to a variety of rock motions including bouncing, sliding, skipping and rolling. Depending on the impact configuration a wide range of motions is possible. This explains the large scatter of apparent restitution coefficients. We present a rockfall model based on newly developed hard-contact algorithms which includes the effects of rock shape and therefore is able to reproduce the results of different impact configurations. We simulate the laboratory experiments to show that it is possible to reproduce run-out and dispersion of different rock shapes using parameters obtained from independent tests. Although this is a step forward in rockfall trajectory modelling, the problem of parametersing real terrain remains.
On the distribution of seismic reflection coefficients and seismic amplitudes
Painter, S.; Paterson, L.; Beresford, G.
1995-07-01
Reflection coefficient sequences from 14 wells in Australia have a statistical character consistent with a non-Gaussian scaling noise model based on the Levy-stable family of probability distributions. Experimental histograms of reflection coefficients are accurately approximated by symmetric Levy-stable probability density functions with Levy index between 0.99 and 1.43. These distributions have the same canonical role in mathematical statistics as the Gaussian distribution, but they have slowly decaying tails and infinite moments. The distribution of reflection coefficients is independent of the spatial scale (statistically self-similar), and the reflection coefficient sequences have long-range dependence. These results suggest that the logarithm of seismic impedance can be modeled accurately using fractional Levy motion, which is a generalization of fractional Brownian motion. Synthetic seismograms produced from the authors` model for the reflection coefficients also have Levy-stable distributions. These isolations include transmission losses, the effects of reverberations, and the loss of resolution caused by band-limited wavelets, and suggest that actual seismic amplitudes with sufficient signal-to-noise ratio should also have a Levy-stable distribution. This prediction is verified using post-stack seismic data acquired in the Timor Sea and in the continental USA. However, prestack seismic amplitudes from the Timor Sea are nearly Gaussian. They attribute the difference between prestack and poststack data to the high level of measurement noise in the prestack data.
Improved diffusion coefficients generated from Monte Carlo codes
Herman, B. R.; Forget, B.; Smith, K.; Aviles, B. N.
2013-07-01
Monte Carlo codes are becoming more widely used for reactor analysis. Some of these applications involve the generation of diffusion theory parameters including macroscopic cross sections and diffusion coefficients. Two approximations used to generate diffusion coefficients are assessed using the Monte Carlo code MC21. The first is the method of homogenization; whether to weight either fine-group transport cross sections or fine-group diffusion coefficients when collapsing to few-group diffusion coefficients. The second is a fundamental approximation made to the energy-dependent P1 equations to derive the energy-dependent diffusion equations. Standard Monte Carlo codes usually generate a flux-weighted transport cross section with no correction to the diffusion approximation. Results indicate that this causes noticeable tilting in reconstructed pin powers in simple test lattices with L2 norm error of 3.6%. This error is reduced significantly to 0.27% when weighting fine-group diffusion coefficients by the flux and applying a correction to the diffusion approximation. Noticeable tilting in reconstructed fluxes and pin powers was reduced when applying these corrections. (authors)
Assessment of the aversion coefficient in nuclear safety in Hungary.
Eged, Katalin; Kanyár, Béla; Kis, Zoltán; Tatay, Tibor
2002-06-01
The key elements of the optimization practice as applied to radiation protection are the monetary value of the averted person-sievert and the aversion coefficient. Determination of the monetary value of the unit averted person-sievert (as alpha(base)-parameter) in Hungary was presented in a previous paper. The estimation of this parameter was carried out by the willingness-to-pay (WTP) method associated with averted occupational exposure (at the NPP Paks/Hungary). The aversion coefficient predicts the importance of dose reduction based on the magnitude of the dose. The assessment of the aversion coefficient occurred also by means of the WTP method in the spring of 2000. Its value has been estimated on the basis of individual preferences concerning the distribution of individual exposure in nuclear safety. The results achieved by the WTP among the radiation specialists from the NPP Paks, Hungary, assessed a value for the aversion coefficient of 1.86 over the whole range of individual exposure levels. This value is a bit greater than the value obtained in France (1.7) and the higher coefficient expresses a higher priority to reduce the highest individual exposures. PMID:12046754
Krieger, Nancy; Chen, Jarvis T.; Waterman, Pamela D.; Rehkopf, David H.; Subramanian, S. V.
2003-01-01
Use of multilevel frameworks and area-based socioeconomic measures (ABSMs) for public health monitoring can potentially overcome the absence of socioeconomic data in most US public health surveillance systems. To assess whether ABSMs can meaningfully be used for diverse race/ethnicity–gender groups, we geocoded and linked public health surveillance data from Massachusetts and Rhode Island to 1990 block group, tract, and zip code ABSMs. Outcomes comprised death, birth, cancer incidence, tuberculosis, sexually transmitted infections, childhood lead poisoning, and nonfatal weapons-related injuries. Among White, Black, and Hispanic women and men, measures of economic deprivation (e.g., percentage below poverty) were most sensitive to expected socioeconomic gradients in health, with the most consistent results and maximal geocoding linkage evident for tract-level analyses. PMID:14534218
NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species
NASA Technical Reports Server (NTRS)
McBride, Bonnie J.; Zehe, Michael J.; Gordon, Sanford
2002-01-01
This report documents the library of thermodynamic data used with the NASA Glenn computer program CEA (Chemical Equilibrium with Applications). This library, containing data for over 2000 solid, liquid, and gaseous chemical species for temperatures ranging from 200 to 20,000 K, is available for use with other computer codes as well. The data are expressed as least-squares coefficients to a seven-term functional form for C((sup o)(sub p)) (T) / R with integration constants for H (sup o) (T) / RT and S(sup o) (T) / R. The NASA Glenn computer program PAC (Properties and Coefficients) was used to calculate thermodynamic functions and to generate the least-squares coefficients. PAC input was taken from a variety of sources. A complete listing of the database is given along with a summary of thermodynamic properties at 0 and 298.15 K.
INTERNAL CONVERSION COEFFICIENTS - HOW GOOD ARE THEY NOW?
KIBEDI,T.; BURROWS, T.W.; TRZHASKOVSKAYA, M.B.; NESTOR, JR., C.W.; DAVIDSON, P.M.
2007-04-22
Internal conversion coefficients involving atomic electrons (ICC) and electron-positron pairs (IPC) are often required to determine transition multipolarities and total transition rates. A new internal conversion coefficient data base, BrIcc has been developed which integrates a number of tabulations on ICC and IPC, as well as {Omega}(E0) electronic factors. To decide which theoretical internal conversion coefficient table to use, the accurately determined experimental {alpha}{sub K}, {alpha}{sub L}, {alpha}{sub Total} and {alpha}{sub K}/{alpha}{sub L} values were compared with the new Dirac-Fock calculations using extreme assumptions on the effect of the atomic vacancy. While the overall difference between experiment and theory is less than 1%, our analysis shows preference towards the so called ''Frozen Orbital'' approximation, which takes into account the effect of the atomic vacancy.
Diffusion coefficient and shear viscosity of rigid water models.
Tazi, Sami; Boţan, Alexandru; Salanne, Mathieu; Marry, Virginie; Turq, Pierre; Rotenberg, Benjamin
2012-07-18
We report the diffusion coefficient and viscosity of popular rigid water models: two non-polarizable ones (SPC/E with three sites, and TIP4P/2005 with four sites) and a polarizable one (Dang-Chang, four sites). We exploit the dependence of the diffusion coefficient on the system size (Yeh and Hummer 2004 J. Phys. Chem. B 108 15873) to obtain the size-independent value. This also provides an estimate of the viscosity of all water models, which we compare to the Green-Kubo result. In all cases, a good agreement is found. The TIP4P/2005 model is in better agreement with the experimental data for both diffusion and viscosity. The SPC/E and Dang-Chang models overestimate the diffusion coefficient and underestimate the viscosity. PMID:22739097
Mutual diffusion coefficients in systems containing the nickel ion
NASA Astrophysics Data System (ADS)
Ribeiro, Ana C. F.; Veríssimo, Luis V. M. M.; Gomes, Joselaine C. S.; Santos, Cecilia I. A. V.; Barros, Marisa C. F.; Lobo, Victor M. M.; Sobral, Abílio J. F. N.; Esteso, Miguel A.; Leaist, Derek G.
2013-04-01
Mutual diffusion coefficients of nickel chloride in water have been measured at 293.15 K and 303.15 K and at concentrations between 0.020 mol dm-3 and 0.100 mol dm-3, using a conductimetric cell. The experimental mutual diffusion coefficients are discussed on the basis of the Onsager-Fuoss model. The equivalent conductances at infinitesimal concentration of the nickel ion in these solutions at those temperatures have been estimated using these results. In addition, from these data, we have estimated some transport and structural parameters, such as limiting diffusion coefficient, ionic conductance at infinitesimal concentration, hydrodynamic radii and activation energy, contributing this way to a better understanding of the structure of these systems and of their thermodynamic behavior in aqueous solution at different concentrations.
Optimization of Power Coefficient of Wind Turbine Using Genetic Algorithm
NASA Astrophysics Data System (ADS)
Rajakumar, Sappani; Ravindran, Durairaj; Sivakumar, Mahalingam; Venkatachalam, Gopalan; Muthukumar, Shunmugavelu
2016-06-01
In the design of a wind turbine, the goal is to attain the highest possible power output under specified atmospheric conditions. The optimization of power coefficient of horizontal axis wind turbine has been carried out by integration of blade element momentum method and genetic algorithm (GA). The design variables considered are wind velocity, angle of attack and tip speed ratio. The objective function is power coefficient of wind turbine. The different combination of design variables are optimized using GA and then the Power coefficient is optimized. The optimized design variables are validated with the experimental results available in the literature. By this optimization work the optimum design variables of wind turbine can be found economically than experimental work. NACA44XX series airfoils are considered for this optimization work.
Calculations of accommodation coefficients for diatomic molecular gases.
Ambaye, Hailemariam; Manson, J R
2006-03-01
A theoretical study of energy and momentum accommodation coefficients and reduced force coefficients for molecular gases exchanging energy with surfaces has been carried out. The theoretical model uses classical mechanics for describing translational and rotational motions while internal molecular vibrational modes are treated quantum mechanically. Calculations for diatomic molecular gases are compared with recent measurements using hypersonic beams of N2 incident on SiO2 layers deposited on Kapton substrates. The theory gives good qualitative predictions of the behavior of the various accommodation coefficients as functions of the available experimentally controllable parameters such as incident translational energy, incident beam angle, molecular and surface masses, and surface temperature. Quantitative comparisons with measurements for energy and normal momentum accommodation indicate that these experiments can be used to obtain basic physical information about the molecule-surface interaction such as the physisorption potential well depth and the extent of surface roughness. PMID:16605510
Derivation of anisotropic diffusion coefficients in a large annular cavity
Eiichi Suetomi; Hiroshi Sekimoto )
1993-06-01
A small reactor for a spacecraft or a small liquid-metal reactor for urban siting, decentralized electrical units, or seawater desalination is designed for a large leakage of neutrons from the reactor core. In these reactors, a movable annular reflector is used for reactivity control. Therefore, a large annular cavity exists between the core and the shielding materials. In this paper, anisotropic diffusion coefficients for a large annular cavity are derived by equating the neutron currents obtained by the diffusion equation and by the transport equation. These diffusion coefficients depend only on the geometrical configuration of the cavity. A numerical comparison of diffusion calculations using these diffusion coefficients and transport calculations shows good agreement.
RECOMBINATION RATE COEFFICIENTS OF BORON-LIKE Ne
Mahmood, S.; Orban, I.; Ali, S.; Schuch, R.; Glans, P.; Bleda, E. A.; Altun, Z.
2013-07-10
Recombination of Ne{sup 5+} was measured in a merged-beam type experiment at the heavy-ion storage ring CRYRING. In the collision energy range 0-110 eV resonances due to 2s {sup 2}2p {yields} 2s2p {sup 2} ({Delta}n = 0) and 2s {sup 2}2p {yields} 2s {sup 2}3l ({Delta}n = 1), core excitations were observed. The experimentally derived rate coefficients agree well with the calculations obtained using AUTOSTRUCTURE. At low energies, recombination is dominated by resonances belonging to the spin-forbidden 2s2p {sup 2}({sup 4} P{sub J})nl series. The energy-dependent rate coefficients were convoluted with a Maxwell-Boltzmann electron energy distribution to obtain plasma recombination rate coefficients. The data from the literature deviate from the measured results at low temperature.
Innovative Fast Reactors: Impact of Fuel Composition on Reactivity Coefficients
G. Palmiotti; M. Salvatores; M. Asswaroongruengchot
2009-12-01
A major challenge for future Fast Reactors could be the recycling of minor actinides (MA) in the core fuel, in order to minimize wastes and contribute to meet both the sustainability objective and the reduction of the burden on a geological disposal. Although the most outstanding issues will be found in the development and validation of the appropriate fuels, the presence of MA in the core can potentially deteriorate the core reactivity coefficients. In the present paper we will show however that there is no physical limit to the amount of MA in the core fuel, but that a careful physics analysis can indicate the most appropriate measures to reduce the MA impact on the reactivity coefficients, and in particular, for Na cooled reactors, on the Na void reactivity coefficient.
Coupling coefficients for tensor product representations of quantum SU(2)
Groenevelt, Wolter
2014-10-15
We study tensor products of infinite dimensional irreducible {sup *}-representations (not corepresentations) of the SU(2) quantum group. We obtain (generalized) eigenvectors of certain self-adjoint elements using spectral analysis of Jacobi operators associated to well-known q-hypergeometric orthogonal polynomials. We also compute coupling coefficients between different eigenvectors corresponding to the same eigenvalue. Since the continuous spectrum has multiplicity two, the corresponding coupling coefficients can be considered as 2 × 2-matrix-valued orthogonal functions. We compute explicitly the matrix elements of these functions. The coupling coefficients can be considered as q-analogs of Bessel functions. As a results we obtain several q-integral identities involving q-hypergeometric orthogonal polynomials and q-Bessel-type functions.
Modification of Einstein A Coefficient in Dissipative Gas Medium
NASA Technical Reports Server (NTRS)
Cao, Chang-Qi; Cao, Hui; Qin, Ke-Cheng
1996-01-01
Spontaneous radiation in dissipative gas medium such as plasmas is investigated by Langevin equations and the modified Weisskopf-Wigner approximation. Since the refractive index of gas medium is expected to be nearly unity, we shall first neglect the medium polarization effect. We show that absorption in plasmas may in certain case modify the Einstein A coefficient significantly and cause a pit in the A coefficient-density curves for relatively low temperature plasmas and also a pit in the A coefficient-temperature curves. In the next, the effect of medium polarization is taken into account in addition. To our surprise, its effect in certain case is quite significant. The dispersive curves show different behaviors in different region of parameters.
Correlation between Schmidt hardness and coefficient of restitution of rocks
NASA Astrophysics Data System (ADS)
Ansari, M. K.; Ahmad, M.; Singh, Rajesh; Singh, T. N.
2015-04-01
Rockfall, like landslide is the disaster that could cause loss of life and property. Exact rockfall trajectories depends upon, slope geometry, slope roughness, static and dynamic friction, rolling resistance, density of rocks as well as the restitution characteristics of rocks. In all these parameters, coefficients of restitution play a vital role to control the trajectories of the rockfall. In this article, an attempt has been made to calculate the coefficient of restitution using laboratory experiments that include dropping of balls of different rock types on the same rock type slabs as well as same type of rock balls on different types of rock slab. Schmidt hardness has been also calculated for both, balls and slabs. Using these experimental results, an effort has been made to establish the relation between coefficient of restitution (COR) and Schmidt hardness.
Temperature dependence of damage coefficient in electron irradiated solar cells
NASA Technical Reports Server (NTRS)
Faith, T. J.
1973-01-01
Measurements of light-generated current vs cell temperature on electron-irradiated n/p silicon solar cells show the temperature coefficient of this current to increase with increasing fluence for both 10-ohm and 20-ohm cells. A relationship between minority-carrier diffusion length and light-generated current was derived by combining measurements of these two parameters: vs fluence at room temperature, and vs cell temperature in cells irradiated to a fluence of 1 x 10 to the 15th power e/sq cm. This relationship was used, together with the light-generated current data, to calculate the temperature dependence of the diffusion-length damage coefficient. The results show a strong decrease in the damage coefficient with increasing temperature in the range experienced by solar panels in synchronous earth orbit.
Inflationary weak anisotropic model with general dissipation coefficient
NASA Astrophysics Data System (ADS)
Sharif, M.; Saleem, Rabia
2016-03-01
This paper explores the dynamics of warm intermediate and logamediate inflationary models during weak dissipative regime with a general form of dissipative coefficient. We analyze these models within the framework of locally rotationally symmetric Bianchi type I universe. In both cases, we evaluate solution of inflaton, effective scalar potential, dissipative coefficient, slow-roll parameters, scalar and tensor power spectra, scalar spectral index and tensor to scalar ratio under slow-roll approximation. We constrain the model parameters using recent data and conclude that anisotropic inflationary universe model with generalized dissipation coefficient remains compatible with WMAP9, Planck and BICEP2 data. Finally, we have checked the effects of bulk viscous pressure on this considered model and found that it remains compatible with recent data only for intermediate case.
The determination of longitudinal dispersion coefficients in rivers.
Palancar, María C; Aragón, José M; Sánchez, Fernando; Gil, Roberto
2003-01-01
The dispersion coefficient of several sections of two Spanish rivers (Tagus and Ebro) is calculated using different methods. The aim of the study is to accurately know the effects of accidental leaks from two nuclear power plants that are placed upstream. Experimental data from tracer injections as well as data from hydraulic parameters were used to calculate the dispersion coefficient. Two methods based on tracer curves fit the experimental data well. One method is based on the time at which the tracer concentration is half the maximum concentration; the other method is based on the variance of the tracer curve distribution. An alternative method based on governmental data of velocity profiles and correlations of hydraulic parameters was also used. The results of this method are strongly sensitive to small variations in the stream flowrate. A new correlation is proposed to predict the dispersion coefficient with an error smaller than the one provided by other correlations in the literature. PMID:12934826
Transport coefficients for dense hard-disk systems.
García-Rojo, Ramón; Luding, Stefan; Brey, J Javier
2006-12-01
A study of the transport coefficients of a system of elastic hard disks based on the use of Helfand-Einstein expressions is reported. The self-diffusion, the viscosity, and the heat conductivity are examined with averaging techniques especially appropriate for event-driven molecular dynamics algorithms with periodic boundary conditions. The density and size dependence of the results are analyzed, and comparison with the predictions from Enskog's theory is carried out. In particular, the behavior of the transport coefficients in the vicinity of the fluid-solid transition is investigated and a striking power law divergence of the viscosity with density is obtained in this region, while all other examined transport coefficients show a drop in that density range in relation to the Enskog's prediction. Finally, the deviations are related to shear band instabilities and the concept of dilatancy. PMID:17280060
The Inertia Coefficients of an Airship in a Frictionless Fluid
NASA Technical Reports Server (NTRS)
Bateman, H.
1979-01-01
The apparent inertia of an airship hull is examined. The exact solution of the aerodynamical problem is studied for hulls of various shapes with special attention given to the case of an ellipsoidal hull. So that the results for the ellipsoidal hull may be readily adapted to other cases, they are expressed in terms of the area and perimeter of the largest cross section perpendicular to the direction of motion by means of a formula involving a coefficient kappa which varies only slowly when the shape of the hull is changed, being 0.637 for a circular or elliptic disk, 0.5 for a sphere, and about 0.25 for a spheroid of fineness ratio. The case of rotation of an airship hull is investigated and a coefficient is defined with the same advantages as the corresponding coefficient for rectilinear motion.
Geologic and climatic controls on the radon emanation coefficient
Schumann, R.R.; Gundersen, L.C.S.
1997-01-01
Geologic, pedologic, and climatic factors, including radium content, grain size, siting of radon parents within soil grains or on grain coatings, and soil moisture conditions, determine a soil's emanating power and radon transport characteristics. Data from field studies indicate that soils derived from similar parent rocks in different regions have significantly different emanation coefficients due to the effects of climate on these soil characteristics. An important tool for measuring radon source strength (i.e., radium content) is ground-based and aerial gamma radioactivity measurements. Regional correlations between soil radium content, determined by gamma spectrometry, and soil-gas or indoor radon concentrations can be traced to the influence of climatic and geologic factors on intrinsic permeability and radon emanation coefficients. Data on soil radium content, permeability, and moisture content, when combined with data on emanation coefficients, can form a framework for development of quantitative predictive models for radon generation in rocks and soils.
Protein osmotic pressure gradients and microvascular reflection coefficients.
Drake, R E; Dhother, S; Teague, R A; Gabel, J C
1997-08-01
Microvascular membranes are heteroporous, so the mean osmotic reflection coefficient for a microvascular membrane (sigma d) is a function of the reflection coefficient for each pore. Investigators have derived equations for sigma d based on the assumption that the protein osmotic pressure gradient across the membrane (delta II) does not vary from pore to pore. However, for most microvascular membranes, delta II probably does vary from pore to pore. In this study, we derived a new equation for sigma d. According to our equation, pore-to-pore differences in delta II increase the effect of small pores and decrease the effect of large pores on the overall membrane osmotic reflection coefficient. Thus sigma d for a heteroporous membrane may be much higher than previously derived equations indicate. Furthermore, pore-to-pore delta II differences increase the effect of plasma protein osmotic pressure to oppose microvascular fluid filtration. PMID:9277520
Microchip for the Measurement of Seebeck Coefficients of Single Nanowires
NASA Astrophysics Data System (ADS)
Völklein, F.; Schmitt, M.; Cornelius, T. W.; Picht, O.; Müller, S.; Neumann, R.
2009-07-01
Bismuth nanowires were electrochemically grown in ion track-etched polycarbonate membranes. Micromachining and microlithography were employed to realize a newly developed microchip for Seebeck coefficient measurements on individual nanowires. By anisotropic etching of a (100) Si wafer, an 800-nm-thick SiO2/Si3N4 membrane was prepared in the chip center. The low thermal conductivity of the membrane is crucial to obtain the required temperature difference Δ T along the nanowire. The wire is electrically contacted to thin metal pads which are patterned by a new method of microscopic exposure of photoresist and a lift-off process. A Δ T between the two pairs of contact pads, located on the membrane, is established by a thin-film heater. Applying the known Seebeck coefficient of a reference film, the temperature difference at this gap is determined. Using Δ T and the measured Seebeck voltage U of the nanowire, its Seebeck coefficient can be calculated.
Townsend coefficients for electron scattering over dielectric surfaces
NASA Technical Reports Server (NTRS)
Peck, Timothy L.; Kushner, Mark J.
1988-01-01
A method for describing the probability of initiating flashover discharges across dielectric surfaces is presented in which a transport coefficient for electron multiplication similar to the Townsend coefficient used for gas discharges is defined. The coefficient is a function of the scaling parameter (charge released from the cathode)/(cathode-anode separation) and is also a measure of the growth of the sheath on the dielectric surface resulting from electron scattering. Results are discussed as to when the source of seed electrons does not necessarily depend upon field emission at the cathode-vacuum-dielectric triple point. For these conditions, there is a different functional dependence of flashover probability on voltage and geometry than when field emission provides the seed electrons. As a result, criteria previously used to predict flashover discharges may not apply.
High Pressure Seebeck Coefficient Measurements Using Paris-Edinburgh Cell
NASA Astrophysics Data System (ADS)
Baker, Jason; Kumar, Ravhi; Park, Changyong; Kenney-Benson, Curtis; Velisavljevic, Nenad; Hipsec; Department Of Physics, University Of Nevada, Las Vegas Collaboration; Hpcat, Geophysical Laboratory, Carnegie Institution Of Washington Collaboration; Shock; Detonation Physics Group, Los Alamos National Laboratory Collaboration
We have developed a new type of sample cell assembly for the Paris-Edinburgh (PE) type large volume press for simultaneous x-ray diffraction, electrical resistance, and thermal measurements at high pressures. We demonstrate the feasibility of performing in situ measurements of the Seebeck coefficient over a broad range of pressure-temperature conditions by observing the well-known solid-solid and solid-melt transitions of bismuth (Bi) up to 3GPa and 450 K. We observed a gradual increase in the Seebeck coefficient which becomes positive during transition to the Bi - II phase. Also, we have performed successful Seebeck coefficient measurements on the thermoelectric material PbTe. This new capability enables us to directly correlate pressure-induced structural phase transitions to electrical and thermal properties.
Multiple element airfoils optimized for maximum lift coefficient.
NASA Technical Reports Server (NTRS)
Ormsbee, A. I.; Chen, A. W.
1972-01-01
Optimum airfoils in the sense of maximum lift coefficient are obtained for incompressible fluid flow at large Reynolds number. The maximum lift coefficient is achieved by requiring that the turbulent skin friction be zero in the pressure rise region on the airfoil upper surface. Under this constraint, the pressure distribution is optimized. The optimum pressure distribution is a function of Reynolds number and the trailing edge velocity. Geometries of those airfoils which will generate these optimum pressure distributions are obtained using a direct-iterative method which is developed in this study. This method can be used to design airfoils consisting of any number of elements. Numerical examples of one- and two-element airfoils are given. The maximum lift coefficients obtained range from 2 to 2.5.
Determination of decay coefficients for combustors with acoustic absorbers
NASA Technical Reports Server (NTRS)
Mitchell, C. E.; Espander, W. R.; Baer, M. R.
1972-01-01
An analytical technique for the calculation of linear decay coefficients in combustors with acoustic absorbers is presented. Tuned circumferential slot acoustic absorbers were designed for the first three transverse modes of oscillation, and decay coefficients for these absorbers were found as a function of backing distance for seven different chamber configurations. The effectiveness of the absorbers for off-design values of the combustion response and acoustic mode is also investigated. Results indicate that for tuned absorbers the decay coefficient increases approximately as the cube of the backing distance. For most off-design situations the absorber still provides a damping effect. However, if an absorber designed for some higher mode of oscillation is used to damp lower mode oscillations, a driving effect is frequently found.
Measuring the Soret coefficient of nanoparticles in a dilute suspension
Zhao, Chao; Fu, Jinxin; Oztekin, Alparslan; Cheng, Xuanhong
2014-01-01
Thermophoresis is an efficient process for the manipulation of molecules and nanoparticles due to the strong force it generates on the nanoscale. Thermophoresis is characterized by the Soret coefficient. Conventionally, the Soret coefficient of nanosized species is obtained by fitting the concentration profile under a temperature gradient at the steady state to a continuous phase model. However, when the number density of the target is ultralow and the dispersed species cannot be treated as a continuous phase, the bulk concentration fluctuates spatially, preventing extraction of temperature-gradient induced concentration profile. The present work demonstrates a strategy to tackle this problem by superimposing snapshots of nanoparticle distribution. The resulting image is suitable for the extraction of the Soret coefficient through the conventional data fitting method. The strategy is first tested through a discrete phase model that illustrates the spatial fluctuation of the nanoparticle concentration in a dilute suspension in response to the temperature gradient. By superimposing snapshots of the stochastic distribution, a thermophoretic depletion profile with low standard error is constructed, indicative of the Soret coefficient. Next, confocal analysis of nanoparticle distribution in response to a temperature gradient is performed using polystyrene nanobeads down to 1e-5% (v/v). The experimental results also reveal that superimposing enhances the accuracy of extracted Soret coefficient. The critical particle number density in the superimposed image for predicting the Soret coefficient is hypothesized to depend on the spatial resolution of the image. This study also demonstrates that the discrete phase model is an effective tool to study particle migration under thermophoresis in the liquid phase. PMID:25221433
Measuring the Soret coefficient of nanoparticles in a dilute suspension.
Zhao, Chao; Fu, Jinxin; Oztekin, Alparslan; Cheng, Xuanhong
2014-10-01
Thermophoresis is an efficient process for the manipulation of molecules and nanoparticles due to the strong force it generates on the nanoscale. Thermophoresis is characterized by the Soret coefficient. Conventionally, the Soret coefficient of nanosized species is obtained by fitting the concentration profile under a temperature gradient at the steady state to a continuous phase model. However, when the number density of the target is ultralow and the dispersed species cannot be treated as a continuous phase, the bulk concentration fluctuates spatially, preventing extraction of temperature-gradient induced concentration profile. The present work demonstrates a strategy to tackle this problem by superimposing snapshots of nanoparticle distribution. The resulting image is suitable for the extraction of the Soret coefficient through the conventional data fitting method. The strategy is first tested through a discrete phase model that illustrates the spatial fluctuation of the nanoparticle concentration in a dilute suspension in response to the temperature gradient. By superimposing snapshots of the stochastic distribution, a thermophoretic depletion profile with low standard error is constructed, indicative of the Soret coefficient. Next, confocal analysis of nanoparticle distribution in response to a temperature gradient is performed using polystyrene nanobeads down to 1e-5% (v/v). The experimental results also reveal that superimposing enhances the accuracy of extracted Soret coefficient. The critical particle number density in the superimposed image for predicting the Soret coefficient is hypothesized to depend on the spatial resolution of the image. This study also demonstrates that the discrete phase model is an effective tool to study particle migration under thermophoresis in the liquid phase. PMID:25221433
Van der Waals coefficients beyond the classical shell model
Tao, Jianmin; Fang, Yuan; Hao, Pan; Scuseria, G. E.; Ruzsinszky, Adrienn; Perdew, John P.
2015-01-14
Van der Waals (vdW) coefficients can be accurately generated and understood by modelling the dynamic multipole polarizability of each interacting object. Accurate static polarizabilities are the key to accurate dynamic polarizabilities and vdW coefficients. In this work, we present and study in detail a hollow-sphere model for the dynamic multipole polarizability proposed recently by two of the present authors (JT and JPP) to simulate the vdW coefficients for inhomogeneous systems that allow for a cavity. The inputs to this model are the accurate static multipole polarizabilities and the electron density. A simplification of the full hollow-sphere model, the single-frequency approximation (SFA), circumvents the need for a detailed electron density and for a double numerical integration over space. We find that the hollow-sphere model in SFA is not only accurate for nanoclusters and cage molecules (e.g., fullerenes) but also yields vdW coefficients among atoms, fullerenes, and small clusters in good agreement with expensive time-dependent density functional calculations. However, the classical shell model (CSM), which inputs the static dipole polarizabilities and estimates the static higher-order multipole polarizabilities therefrom, is accurate for the higher-order vdW coefficients only when the interacting objects are large. For the lowest-order vdW coefficient C{sub 6}, SFA and CSM are exactly the same. The higher-order (C{sub 8} and C{sub 10}) terms of the vdW expansion can be almost as important as the C{sub 6} term in molecular crystals. Application to a variety of clusters shows that there is strong non-additivity of the long-range vdW interactions between nanoclusters.
Transport coefficients of solid particles immersed in a viscous gas.
Garzó, Vicente; Fullmer, William D; Hrenya, Christine M; Yin, Xiaolong
2016-01-01
Transport properties of a suspension of solid particles in a viscous gas are studied. The dissipation in such systems arises from two sources: inelasticity in particle collisions and viscous dissipation due to the effect of the gas phase on the particles. Here we consider a simplified case in which the mean relative velocity between the gas and solid phases is taken to be zero, such that "thermal drag" is the only remaining gas-solid interaction. Unlike the previous, more general, treatment of the drag force [Garzó et al., J. Fluid Mech. 712, 129 (2012)]JFLSA70022-112010.1017/jfm.2012.404, here we take into account contributions to the (scaled) transport coefficients η^{*} (shear viscosity), κ^{*} (thermal conductivity), and μ^{*} (Dufour-like coefficient) coming from the temperature dependence of the (dimensionless) friction coefficient γ^{*} characterizing the amplitude of the drag force. At moderate densities, the thermal drag model (which is based on the Enskog kinetic equation) is solved by means of the Chapman-Enskog method and the Navier-Stokes transport coefficients are determined in terms of the coefficient of restitution, the solid volume fraction, and the friction coefficient. The results indicate that the effect of the gas phase on η^{*} and μ^{*} is non-negligible (especially in the case of relatively dilute systems) while the form of κ^{*} is the same as the one obtained in the dry granular limit. Finally, as an application of these results, a linear stability analysis of the hydrodynamic equations is carried out to analyze the conditions for stability of the homogeneous cooling state. A comparison with direct numerical simulations shows a good agreement for conditions of practical interest. PMID:26871141
[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
Virial coefficients and equation of state of hard chain molecules
NASA Astrophysics Data System (ADS)
Boublík, Tomáš
2003-10-01
The second, third, and fourth virial coefficients of hard chain molecules with number of segments up to 10 (up to 7 in the case of the fourth one) and the reduced distances L*=1 and 0.5 were determined numerically. For fused hard sphere (FHS) molecules the enlarged fused hard sphere model is introduced which forms a connection to the hard convex geometry and makes it possible to determine the virial coefficients of FHS molecules from the expressions derived for hard convex bodies. Our numerical values of the virial coefficients together with data from literature are used to test the proposed method and to compare its results with values from Wertheim's theory, from its modified version and from the generalized Flory dimer approach. It is found that prediction of the second virial coefficient is very accurate (for L=0.5 the maximum deviation amounts 0.2 percent) and that our values of the third virial coefficient for higher members of the FHS family are superior to those from other considered methods. The model is successfully used to predict geometric characteristics of the hard models of n-butane conformers and to estimate their second virial coefficients. The equation of state of hard prolate spherocylinders in which the nonsphericity parameters of the enlarged FHS model are considered is used to predict the P-V-T behavior of hard dumbbells, hard triatomics, mixture of hard dumbells of different site-site distances, and n-butane taken as a mixture of conformers. In all the cases prediction within error bars is obtained.
Using VPHOT and PTGP to Generate Transformation Coefficients (Abstract)
NASA Astrophysics Data System (ADS)
Menzies, K.; Myers, G.
2015-06-01
(Abstract only) The AAVSO web site hosts two useful tools, VPHOT and PTGP, to help develop your transformation coefficients. They can be used together to simplify a tedious process involving standard comparison star selection, image reduction and spreadsheet analysis. The process necessary to generate Transformation Coefficients involves: (1) measurement of instrumental magnitudes of Standard Comparison Stars, (2) measurement of instrumental magnitudes for a set of images and filters (UBVRI), and (3) downloading of comparison star magnitude files in a standard format. The subsequent process involves: (4) importing the set of standard comparison star magnitude files into PTGP, and (5) the automatic calculation of transformation coefficients and transformation plots. During testing in vphot and PTGP, simple steps and alternatives have been identified to generate accurate transform coefficients. The first VPHOT step is the obvious need to upload multiple images in multiple standard filters to VPHOT. The second step is to open each image, overlay all standard comparison stars (currently M67 or NGC 7790), view the photometry table, and download the comparison star magnitude data files. Two alternatives involve either the use of individual image files (for example, 4B, 4V, 4R; 4I) or the stacking of all images for each filter (for example, 1B, 1V, 1R; 1I). The latter improves the SNR. In PTGP after the selection of telescope, standard fields, and data reduction software, one selects all comp star magnitude files. The “Calculate Transform Set” button calculates the applicable filter magnitude and color index coefficients. Testing of this process included an evaluation of the impact of several alternatives including: (1) choice of individual filter images or stacked filter images, (2) choice of all standard comparison stars or a selected subset of standard comparison stars, and (3) choice of a minimum SNR. Each of these alternatives affects the transformation
Application of distribution coefficients to radiological assessment models
Schell, W.R.; Sanchez, A.L.; Underhill, D.W.; Thomas, E.
1985-01-01
A field and laboratory investigation of the transport of fallout radionuclides in natural, organic rich ecosystems has been initiated. Mountain-top peat bogs in Pennsylvania, New York and Virginia were sampled by coring, dated by Pb-210 methods and measured for bomb-produced Sr-90, Pu-239, 240, and Cs-137; laboratory measurements of the distribution coefficients for Cs-137, Sr-85, Ru-106, Am-241, and Co-57 by the constant shaking method have been made. These natural terrestrial ecosystems are labeled with fallout radionuclides from nuclear weapons tests which are environmental tracers of element transport. To explain the differences between the input from fallout and the distribution of Cs-137 in peat cores, a simple ''theoretical plate'' transport model has been used. Each year of growth is assumed to be a ''theoretical plate'' and Cs-137 deposited is transferred between plates by advection and mixing processes. The annual deposition of Cs-137 occurs on the (then) uppermost layer and is proportional to the atmospheric input. The theoretical plate model finds values of the advection and mixing coefficients which give the best fit between Cs-137 profile in the bog and the atmospherically-derived Cs-137. For the three bogs tested so far, the advection coefficients indicate an upward movement of Cs-137 as well as downward transport. Values for the diffusion coefficient range from 10E/sup -7/ to 10E/sup -9/ cm/sup 2/ s/sup -1/ depending on organic content and porosity. The mass transport values from the model are compared to laboratory measurements of distribution coefficients in simulated acid rain conditions. Based on the diffusion coefficients calculated from the model, a thickness of 8 to 20 cm of peat surrounding a leaking cannister of Cs-137 would not allow the radionuclide to enter an aquifer for 300 years from a low level waste disposal site.
Scattering and absorption coefficients of silica-doped alumina aerogels.
Fu, Tairan; Tang, Jiaqi; Chen, Kai; Zhang, Fan
2016-02-01
Alumina-based aerogels are especially useful in many applications due to their excellent stability at high temperatures. This study experimentally analyzed the radiative properties of silica-doped alumina aerogels through spectral directional-hemispherical measurements for wavelengths of 0.38-25 μm. The silica-doped alumina aerogel samples were prepared with a 1.4∶1 molar ratio of silica to alumina. A two-flux model was used to describe the radiation propagation in a 1D scattering absorbing sample to derive expressions for the normal-hemispherical transmittances and reflectances based on the transport approximation. The normal-hemispherical transmittances and reflectances were measured at various spectral wavelengths and sample thicknesses using the integrating sphere method. The spectral absorption and transport scattering coefficients of silica-doped alumina aerogels were then determined from the measured normal-hemispherical data. The absorption and transport scattering coefficients of silica-doped alumina aerogels are (0.1 cm-1, 36 cm-1) and (0.1 cm-1, 112 cm-1) for wavelengths of 0.38-8.0 μm. The spectral transport scattering coefficient varies in the opposite direction from the spectral absorption coefficient for various wavelengths. The radiative properties for silica and alumina aerogels were quite different for the absorption coefficient for wavelengths of 2.5-8.0 μm and for the transport scattering coefficient for wavelengths of 0.38-2.5 and 3.5-6.0 μm. The measured radiative properties were used to predict the spectral normal-hemispherical reflectance and transmittance of the silica-doped alumina aerogels for various sample thicknesses and wavelengths. The predicted values do not change for the sample thicknesses greater than a critical value. The analysis provides valuable reference data for alumina aerogels for high-temperature applications. PMID:26836071
Transport coefficients of solid particles immersed in a viscous gas
NASA Astrophysics Data System (ADS)
Garzó, Vicente; Fullmer, William D.; Hrenya, Christine M.; Yin, Xiaolong
2016-01-01
Transport properties of a suspension of solid particles in a viscous gas are studied. The dissipation in such systems arises from two sources: inelasticity in particle collisions and viscous dissipation due to the effect of the gas phase on the particles. Here we consider a simplified case in which the mean relative velocity between the gas and solid phases is taken to be zero, such that "thermal drag" is the only remaining gas-solid interaction. Unlike the previous, more general, treatment of the drag force [Garzó et al., J. Fluid Mech. 712, 129 (2012)], 10.1017/jfm.2012.404, here we take into account contributions to the (scaled) transport coefficients η* (shear viscosity), κ* (thermal conductivity), and μ* (Dufour-like coefficient) coming from the temperature dependence of the (dimensionless) friction coefficient γ* characterizing the amplitude of the drag force. At moderate densities, the thermal drag model (which is based on the Enskog kinetic equation) is solved by means of the Chapman-Enskog method and the Navier-Stokes transport coefficients are determined in terms of the coefficient of restitution, the solid volume fraction, and the friction coefficient. The results indicate that the effect of the gas phase on η* and μ* is non-negligible (especially in the case of relatively dilute systems) while the form of κ* is the same as the one obtained in the dry granular limit. Finally, as an application of these results, a linear stability analysis of the hydrodynamic equations is carried out to analyze the conditions for stability of the homogeneous cooling state. A comparison with direct numerical simulations shows a good agreement for conditions of practical interest.
Coefficients of Productivity for Yellowstone's Grizzly Bear Habitat
Mattson, David John; Barber, Kim; Maw, Ralene; Renkin, Roy
2004-01-01
This report describes methods for calculating coefficients used to depict habitat productivity for grizzly bears in the Yellowstone ecosystem. Calculations based on these coefficients are used in the Yellowstone Grizzly Bear Cumulative Effects Model to map the distribution of habitat productivity and account for the impacts of human facilities. The coefficients of habitat productivity incorporate detailed information that was collected over a 20-year period (1977-96) on the foraging behavior of Yellowstone's bears and include records of what bears were feeding on, when and where they fed, the extent of that feeding activity, and relative measures of the quantity consumed. The coefficients also incorporate information, collected primarily from 1986 to 1992, on the nutrient content of foods that were consumed, their digestibility, characteristic bite sizes, and the energy required to extract and handle each food. Coefficients were calculated for different time periods and different habitat types, specific to different parts of the Yellowstone ecosystem. Stratifications included four seasons of bear activity (spring, estrus, early hyperphagia, late hyperphagia), years when ungulate carrion and whitebark pine seed crops were abundant versus not, areas adjacent to (<100 m) or far away from forest/nonforest edges, and areas inside or outside of ungulate winter ranges. Densities of bear activity in each region, habitat type, and time period were incorporated into calculations, controlling for the effects of proximity to human facilities. The coefficients described in this report and associated estimates of grizzly bear habitat productivity are unique among many efforts to model the conditions of bear habitat because calculations include information on energetics derived from the observed behavior of radio-marked bears.
A technique for measuring dynamic friction coefficient under impact loading
NASA Astrophysics Data System (ADS)
Lin, Y. L.; Qin, J. G.; Chen, R.; Zhao, P. D.; Lu, F. Y.
2014-09-01
We develop a novel setup based on the split Hopkinson pressure bar technique to test the dynamic friction coefficient under impact loading. In the setup, the major improvement is that the end of the incident bar near the specimen is wedge-shaped, which results in a combined compressive and shear loading applied to the specimen. In fact, the shear loading is caused by the interfacial friction between specimen and bars. Therefore, when the two loading force histories are measured, the friction coefficient histories can be calculated without any assumptions and theoretical derivations. The geometry of the friction pairs is simple, and can be either cuboid or cylindrical. Regarding the measurements, two quartz transducers are used to directly record the force histories, and an optical apparatus is designed to test the interfacial slip movement. By using the setup, the dynamic friction coefficient of PTFE/aluminum 7075 friction pairs was tested. The time resolved dynamic friction coefficient and slip movement histories were achieved. The results show that the friction coefficient changes during the loading process, the average data of the relatively stable flat plateau section of the friction coefficient curves is 0.137, the maximum normal pressure is 52 MPa, the maximum relative slip velocity is 1.5 m/s, and the acceleration is 8400 m2/s. Furthermore, the friction test was simulated using an explicit FEM code LS-DYNA. The simulation results showed that the constant pressure and slip velocity can both be obtained with a wide flat plateau incident pulse. For some special friction pairs, normal pressure up to a few hundred MPa, interfacial slip velocities up to 10 m/s, and slip movement up to centimeter-level can be expected.
A technique for measuring dynamic friction coefficient under impact loading.
Lin, Y L; Qin, J G; Chen, R; Zhao, P D; Lu, F Y
2014-09-01
We develop a novel setup based on the split Hopkinson pressure bar technique to test the dynamic friction coefficient under impact loading. In the setup, the major improvement is that the end of the incident bar near the specimen is wedge-shaped, which results in a combined compressive and shear loading applied to the specimen. In fact, the shear loading is caused by the interfacial friction between specimen and bars. Therefore, when the two loading force histories are measured, the friction coefficient histories can be calculated without any assumptions and theoretical derivations. The geometry of the friction pairs is simple, and can be either cuboid or cylindrical. Regarding the measurements, two quartz transducers are used to directly record the force histories, and an optical apparatus is designed to test the interfacial slip movement. By using the setup, the dynamic friction coefficient of PTFE/aluminum 7075 friction pairs was tested. The time resolved dynamic friction coefficient and slip movement histories were achieved. The results show that the friction coefficient changes during the loading process, the average data of the relatively stable flat plateau section of the friction coefficient curves is 0.137, the maximum normal pressure is 52 MPa, the maximum relative slip velocity is 1.5 m/s, and the acceleration is 8400 m(2)/s. Furthermore, the friction test was simulated using an explicit FEM code LS-DYNA. The simulation results showed that the constant pressure and slip velocity can both be obtained with a wide flat plateau incident pulse. For some special friction pairs, normal pressure up to a few hundred MPa, interfacial slip velocities up to 10 m/s, and slip movement up to centimeter-level can be expected. PMID:25273746
NASA Astrophysics Data System (ADS)
Buho, Hoshino; Ruichen, Jia; Nawata, Hiroshi; Abdelaziz, Karamalla; Yoda, Kiyotsugu; Abdel, Babiker
Mesquite (Prosopis spp) are ever green leguminous trees or shrubs. These species are native to North and South America. They were introduced to Sudan in 1917 from South Africa and Egypt and planted in Khartoum state in central Sudan (Broun and Massey, 1929). Mesquite was originally favored as sand dunes stabilizer and as fodder for livestock. However, sparse stands will often form impenetrable thickets formations that hinder movement of humans and animals. Many infestations are along waterways, both natural and constructed, however, plants can grow also well in drier areas away from water sites. Even in natural rangelands it is an aggressive competitor and can quickly invade upland country. Mesquite thickets can out-compete other vegetation, interfere with mustering and block access to watering places. The sharp thorns can injure animals and puncture vehicle tyres. Seeds can stay dormant for years, and therefore seedlings can re-appear in areas that have been previously cleared. The main objective of Remote Sensing Method for Mesquite Control (RSMMC) is to identify pattern and extend of mesquite spread along spatial and temporal variations using remote sensing means, as main part of mesquite control. Estimation of soil moisture by inversion of SAR data can be performed using physical or semi-empirical approaches. The physical approach uses backscattering models that are capable of reproducing the radar backscattering coefficient from the sensor configuration (wavelength, polarization, and incidence angle) and soil parameters (soil moisture and surface roughness for bare soils). This study adopted calculation of PALSAR L-band radar backscattering coefficient (dB), to estimate soil moisture distribution area based on TDR soil moisture ground measurement data. To retrieve soil moisture (mv) from a single radar configuration, it is necessary to establish a relationship between the radar backscattering coefficient (dB) and soil moisture (mv) measurement.
Identification of dynamic coefficients of annular turbulent seals
NASA Technical Reports Server (NTRS)
Nordmann, R.; Massmann, H.
1984-01-01
An identification procedure to determine dynamic coefficients of annular turbulent seals in turbopumps is presented. Measurements were carried out at a built test rig with two symmetrical arranged seals. A rigid rotating shaft is surrounded by an elastically supported housing, which is excited by impact forces. The relative radial motion between the rotating parts and the housing, respectively between the seal surfaces, is measured by displacement pick-ups and from the time signals complex frequency response functions can be calculated. Finally an analytical model, depending on the seal parameters, is fitted to the measured data, to find the dynamic coefficients.
A technique to measure rotordynamic coefficients in hydrostatic bearings
NASA Astrophysics Data System (ADS)
Capaldi, Russell J.
1993-11-01
An experimental technique is described for measuring the rotordynamic coefficients of fluid film journal bearings. The bearing tester incorporates a double-spool shaft assembly that permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit. This configuration yields data that enables determination of the full linear anisotropic rotordynamic coefficient matrices. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Some results are presented for a four-recess, oil-fed hydrostatic journal bearing.
Determination of the heat transfer coefficients in transient heat conduction
NASA Astrophysics Data System (ADS)
Nho Hào, Dinh; Thanh, Phan Xuan; Lesnic, D.
2013-09-01
The determination of the space- or time-dependent heat transfer coefficient which links the boundary temperature to the heat flux through a third-kind Robin boundary condition in transient heat conduction is investigated. The reconstruction uses average surface temperature measurements. In both cases of the space- or time-dependent unknown heat transfer coefficient the inverse problems are nonlinear and ill posed. Least-squares penalized variational formulations are proposed and new formulae for the gradients are derived. Numerical results obtained using the nonlinear conjugate gradient method combined with a boundary element direct solver are presented and discussed.
Ionization coefficient approach to modeling breakdown in nonuniform geometries.
Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Nicolaysen, Scott D.
2003-11-01
This report summarizes the work on breakdown modeling in nonuniform geometries by the ionization coefficient approach. Included are: (1) fits to primary and secondary ionization coefficients used in the modeling; (2) analytical test cases for sphere-to-sphere, wire-to-wire, corner, coaxial, and rod-to-plane geometries; a compilation of experimental data with source references; comparisons between code results, test case results, and experimental data. A simple criterion is proposed to differentiate between corona and spark. The effect of a dielectric surface on avalanche growth is examined by means of Monte Carlo simulations. The presence of a clean dry surface does not appear to enhance growth.
Tilting pad journal bearings - Measured and predicted stiffness coefficients
Parkins, D.W.; Horner, D. Michell Bearings, Newcastle-upon-Tyne )
1993-07-01
This paper presents measured and calculated characteristics of a tilting pad journal bearing suitable for high speed machinery. Descriptions are given of the experimental techniques used with this variety of bearing and the theoretical model for predicting performance. Measured values of pad temperature, eccentricity, attitude angle, and the four stiffness coefficients are given for a range of loads and rotational speeds. Data are given for both load on pad and between pad configurations, the two principal loading arrangements. Comparisons are made between the measured and predicted bearing temperatures and stiffness coefficients over a wide range of values. 11 refs.
Estimation of octanol/water partition coefficients using LSER parameters
Luehrs, Dean C.; Hickey, James P.; Godbole, Kalpana A.; Rogers, Tony N.
1998-01-01
The logarithms of octanol/water partition coefficients, logKow, were regressed against the linear solvation energy relationship (LSER) parameters for a training set of 981 diverse organic chemicals. The standard deviation for logKow was 0.49. The regression equation was then used to estimate logKow for a test of 146 chemicals which included pesticides and other diverse polyfunctional compounds. Thus the octanol/water partition coefficient may be estimated by LSER parameters without elaborate software but only moderate accuracy should be expected.
Effect of electrolytes on the partition coefficient of irbesartan.
Mbah, C J
2005-05-01
The effect of various electrolytes namely monovalent, divalent and trivalent on the partition coefficient of irbesartan between n-octanol and water systems was investigated at room temperature. It was found that all the electrolytes increase the partition coefficient of irbesartan. The uptake of irbesartan by the organic phase from the aqueous phase is increased with increasing salt concentration except for potassium iodide and aluminum chloride. The effect was found to depend on the size and charge of the ions present in solution. PMID:15918582
RECOMBINATION RATE COEFFICIENTS OF Be-LIKE Si
Orban, I.; Boehm, S.; Schuch, R.; Loch, S. D.
2010-10-01
Recombination of Be-like Si{sup 10+} over the 0-43 eV electron-ion energy range is measured at the CRYRING electron cooler. In addition to radiative and dielectronic recombination, the recombination spectrum also shows strong contributions from trielectronic recombination. Below 100 meV, several very strong resonances associated with a spin-flip of the excited electron dominate the spectrum and also dominate the recombination in the photoionized plasma. The resonant plasma rate coefficients corrected for the experimental field ionization are in good agreement with calculated results by Gu and with AUTOSTRUCTURE calculations. All other calculations significantly underestimate the plasma rate coefficients at low temperatures.
Discharge coefficients of cooling holes with radiused and chamfered inlets
NASA Astrophysics Data System (ADS)
Hay, N.; Spencer, A.
1991-06-01
The flow of cooling air within the internal passages of gas turbines is controlled and metered using holes in disks and casings. The effects of inlet radiusing and chamfering of these holes on the discharge coefficient are discussed. Experimental results for a range of radiusing and chamfering ratios for holes of different length to diameter ratios are presented, covering the range of pressure ratios of practical interest. The results indicate that radiusing and chamfering are both beneficial in increasing the discharge coefficient. Increases of 10-30 percent are possible. Chamfered holes give the more desirable performance characteristics in addition to being easier to produce than radiused holes.
A technique to measure rotordynamic coefficients in hydrostatic bearings
NASA Technical Reports Server (NTRS)
Capaldi, Russell J.
1993-01-01
An experimental technique is described for measuring the rotordynamic coefficients of fluid film journal bearings. The bearing tester incorporates a double-spool shaft assembly that permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit. This configuration yields data that enables determination of the full linear anisotropic rotordynamic coefficient matrices. The dynamic force measurements were made simultaneously with two independent systems, one with piezoelectric load cells and the other with strain gage load cells. Some results are presented for a four-recess, oil-fed hydrostatic journal bearing.
Warm Gauge-Flation with General Dissipative Coefficient
NASA Astrophysics Data System (ADS)
Sharif, M.; Saleem, Rabia; Mohsaneen, Sidra
2016-07-01
In this work, we study the effects of generalized dissipative coefficient on the slow-roll inflation driven by non-Abelian gauge field minimally coupled to gravity. The dynamics of warm intermediate and logamediate inflationary models during weak and strong dissipative regimes is analyzed. In both cases, we explore effective scalar potential, slow-roll parameters, scalar and tensor power spectra, scalar spectral index and tensor to scalar ratio under slow-roll conditions. We conclude that our gauge-flationary model with generalized dissipative coefficient remains consistent with the recent data for dissipative parameter m = 3 and m = 1 for weak and strong dissipative eras, respectively.
Conversion coefficients of the isomeric state in {sup 72}Br
Briz, J. A.; Borge, M. J. G.; Maira, A.; Perea, A.; Tengblad, O.; Agramunt, J.; Algora, A.; Estevez, E.; Nacher, E.; Rubio, B.; Fraile, L. M.; Deo, A.; Farrelly, G.; Gelletly, W.; Podolyak, Z.
2010-04-26
In order to determine the Gamow-Teller strength distribution for the N Z nucleus {sup 72}Kr an experiment was performed with a Total Absorption Gamma Spectrometer. To fully accomplish this task it is crucial to determine the multipolarity of the low energy transitions as the spin-parity of the daughter ground state has been debated. This is done by experimental determination of the conversion coefficients. Preliminary results for the multipolarity and conversion coefficients of the transition connecting the isomeric state at 101 keV with the {sup 72}Br ground state are presented.
Interfacial tension and spreading coefficient for thin films.
Tadmor, Rafael; Pepper, Ken G
2008-04-01
We present a modified mathematical expression for the interfacial tension of very thin films. At large thicknesses the modified expression converges to the classic mathematical expression. We use this modified expression to derive an equation for the spreading coefficient as a function of film thickness. The spreading coefficient equation is then used to calculate the equilibrium thickness of a wetting liquid film for a "pancake drop". Our predictions agree with experimental data. The study is subjected to systems with van der Waals interactions only. PMID:18318550
Viscosity and thermal conductivity coefficients of gaseous and liquid oxygen
NASA Technical Reports Server (NTRS)
Hanley, H. J. M.; Mccarty, R. D.; Sengers, J. V.
1974-01-01
Equations and tables are presented for the viscosity and thermal conductivity coefficients of gaseous and liquid oxygen at temperatures between 80 K and 400 K for pressures up to 200 atm. and at temperatures between 80 K and 2000 K for the dilute gas. A description of the anomalous behavior of the thermal conductivity in the critical region is included. The tabulated coefficients are reliable to within about 15% except for a region in the immediate vicinity of the critical point. Some possibilities for future improvements of this reliability are discussed.
A Note on the Linearly and Quadratically Weighted Kappa Coefficients.
Li, Pingke
2016-09-01
The linearly and quadratically weighted kappa coefficients are popular statistics in measuring inter-rater agreement on an ordinal scale. It has been recently demonstrated that the linearly weighted kappa is a weighted average of the kappa coefficients of the embedded 2 by 2 agreement matrices, while the quadratically weighted kappa is insensitive to the agreement matrices that are row or column reflection symmetric. A rank-one matrix decomposition approach to the weighting schemes is presented in this note such that these phenomena can be demonstrated in a concise manner. PMID:27246436
Tilting pad journal bearings - Measured and predicted stiffness coefficients
NASA Astrophysics Data System (ADS)
Parkins, D. W.; Horner, D.
1993-07-01
This paper presents measured and calculated characteristics of a tilting pad journal bearing suitable for high speed machinery. Descriptions are given of the experimental techniques used with this variety of bearing and the theoretical model for predicting performance. Measured values of pad temperature, eccentricity, attitude angle, and the four stiffness coefficients are given for a range of loads and rotational speeds. Data are given for both load on pad and between pad configurations, the two principal loading arrangements. Comparisons are made between the measured and predicted bearing temperatures and stiffness coefficients over a wide range of values.
Reciprocity in the scattering coefficients of acoustic waveguide modes.
Tong, Yuhui; Pan, Jie
2013-09-01
In this Letter, a proof is provided for the reciprocity between modal scattering coefficients of the acoustic waveguides connected by a junction enclosure. The result holds for all waveguide modes and for junction enclosures with locally reactive boundary conditions away from the interfaces between the junction and waveguides. Also provided is a physical interpretation of the reciprocity of the modal scattering coefficients. The scattering of two-dimensional waveguide modes by a right-angled bend in a rectangular duct is used as an illustrating example. PMID:23967907
NICIL: Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library
NASA Astrophysics Data System (ADS)
Wurster, James
2016-08-01
NICIL (Non-Ideal magnetohydrodynamics Coefficients and Ionisation Library) calculates the ionization values and the coefficients of the non-ideal magnetohydrodynamics terms of Ohmic resistivity, the Hall effect, and ambipolar diffusion. Written as a standalone Fortran90 module that can be implemented in existing codes, NICIL is fully parameterizable, allowing the user to choose which processes to include and decide the values of the free parameters. The module includes both cosmic ray and thermal ionization; the former includes two ion species and three species of dust grains (positively charged, negatively charged and neutral), and the latter includes five elements which can be doubly ionized.
Lattice-structures and constructs with designed thermal expansion coefficients
Spadaccini, Christopher; Hopkins, Jonathan
2014-10-28
A thermal expansion-managed lattice structure having a plurality of unit cells each having flexure bearing-mounted tabs supported on a base and actuated by thermal expansion of an actuator having a thermal expansion coefficient greater than the base and arranged so that the tab is inwardly displaced into a base cavity. The flexure bearing-mounted tabs are connected to other flexure-bearing-mounted tabs of adjacent unit cells so that the adjacent unit cells are spaced from each other to accommodate thermal expansion of individual unit cells while maintaining a desired bulk thermal expansion coefficient of the lattice structure as a whole.
Calculation of self-diffusion coefficients in iron
Zhang, Baohua
2014-01-15
On the basis of available P-V-T equation of state of iron, the temperature and pressure dependence of self-diffusion coefficients in iron polymorphs (α, δ, γ and ε phases) have been successfully reproduced in terms of the bulk elastic and expansivity data by means of a thermodynamical model that interconnects point defects parameters with bulk properties. The calculated diffusion parameters, such as self-diffusion coefficient, activation energy and activation volume over a broad temperature range (500-2500 K) and pressure range (0-100 GPa), compare favorably well with experimental or theoretical ones when the uncertainties are considered.
Determination of the First Townsend Coefficient in Pure Isobutane
NASA Astrophysics Data System (ADS)
Lima, Iara B.; Vivaldini, Túlio C.; Gonçalves, Josemary A. C.; Botelho, Suzana; Ridenti, Marco A.; Fonte, Paulo; Mangiarotti, Alessio; Pascholati, Paulo R.; Tobias, Carmen C. Bueno
2011-08-01
In this work studies of the first Townsend coefficient (α) behavior in isobutane for reduced electric fields ranging from l39Td up to 2O8Td are presented. Pure isobutane has been widely used in Resistive Plate Chambers (RPCs) and other gaseous detectors because of its excellent timing properties. Regardless of these characteristics, there is a lack of swarm parameters data in the literature for this gas. The measurements were based on the Pulsed Townsend technique. Considering the ratio between the current, measured in avalanche mode, and the primary ionization current, the first Townsend coefficient can be determined. In order to validate the technique, results for nitrogen are also presented.
Optical attenuation coefficient in individual ZnO nanowires.
Little, Anree; Hoffman, Abigail; Haegel, Nancy M
2013-03-11
Attenuation coefficient measurements for the propagation of bandedge luminescence are made on individual ZnO nanowires by combining the localized excitation capability of a scanning electron microscope (SEM) with near-field scanning optical microscopy (NSOM) to record the distribution and intensity of wave-guided emission. Measurements were made for individual nanostructures with triangular cross-sections ranging in diameter from 680 to 2300 nm. The effective attenuation coefficient shows an inverse dependence on nanowire diameter (d(-1)), indicating scattering losses due to non-ideal waveguiding behavior. PMID:23482201
Fractional parentage coefficients using a restricted set of Slater determinants
NASA Astrophysics Data System (ADS)
Hill, Edward George
2014-11-01
In a previous paper a method of calculating atomic physics data, energy levels and photo- and collisional-excitation rates using a restricted set of Slater determinants was demonstrated. This paper extends that work to demonstrate the method of calculating a generalisation of coefficients of fractional parentage using a restricted, and already known, set of Slater determinants. These coefficients can be used in photoionisation, collisional ionisation and autoionisation calculations, and so allow the methods to be extended to allow all of the data required by an atomic kinetic code to be calculated using this scheme.
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
Temperature and Strain Coefficient of Velocity for Langasite SAW Devices
NASA Technical Reports Server (NTRS)
Wilson, W. C.; Atkinson, G. M.
2013-01-01
Surface Acoustic Wave sensors on Langasite substrates are being investigated for aerospace applications. Characterization of the Langasite material properties must be performed before sensors can be installed in research vehicles. The coefficients of velocity for both strain and temperature have been determined. These values have also been used to perform temperature compensation of the strain measurements.
Proximal versus Distal Validity Coefficients for Teacher Observational Instruments
ERIC Educational Resources Information Center
Marzano, Robert J.
2014-01-01
This study examined the use of measures of student learning computed using end-of-year assessments (distal measures) versus measures of student learning associated with a single lesson (proximal measures) as criterion scores for the validity of observations of teachers' pedagogical skills. The validity coefficients computed using distal…
Highlighting material structure with transmission electron diffraction correlation coefficient maps.
Kiss, Ákos K; Rauch, Edgar F; Lábár, János L
2016-04-01
Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast. PMID:26866276
An Iterative Method for Solving Variable Coefficient ODEs
ERIC Educational Resources Information Center
Deeba, Elias; Yoon, Jeong-Mi; Zafiris, Vasilis
2003-01-01
In this classroom note, the authors present a method to solve variable coefficients ordinary differential equations of the form p(x)y([squared])(x) + q(x)y([superscript 1])(x) + r(x)y(x) = 0. They propose an iterative method as an alternate method to solve the above equation. This iterative method is accessible to an undergraduate student studying…
Vapor pressures and gas-film coefficients for ketones
Rathbun, R.E.; Tai, D.Y.
1987-01-01
Comparison of handbook vapor pressures for seven ketones with more recent literature data showed large differences for four of the ketones. Gas-film coefficients for the volatilization of these ketones from water determined by two different methods were in reasonable agreement. ?? 1987.
Determination of crop coefficients (Kc) for irrigation management of crops
Technology Transfer Automated Retrieval System (TEKTRAN)
Weighing lysimeters are used to measure crop water use during the growing season. By relating the water use of a specific crop to a well-watered reference crop such as grass, crop coefficients (Kc) can be developed to assist in predicting crop needs using meteorological data available from weather ...
Dissociation and Mass Transfer Coefficients for Ammonia Volatilization Models
Technology Transfer Automated Retrieval System (TEKTRAN)
Process-based models are being used to predict ammonia emissions from manure sources, but their accuracy has not been fully evaluated for cattle manure. Laboratory trials were conducted to measure the dissociation and mass transfer coefficients for ammonia volatilization from media of buffered ammon...
Simplified Models for the Drag Coefficient of a Pitched Baseball
ERIC Educational Resources Information Center
Kagan, David; Nathan, Alan M.
2014-01-01
The classic experiment to measure the drag coefficient involves dropping coffee filters. Wouldn't it be more fun to try something different? In fact, an experiment on the drag force is conducted nearly 4000 times a day during the baseball season and you have free access to this PITCHf/x data!
Simplified Models for the Drag Coefficient of a Pitched Baseball
NASA Astrophysics Data System (ADS)
Kagan, David; Nathan, Alan M.
2014-05-01
The classic experiment to measure the drag coefficient involves dropping coffee filters. Wouldn't it be more fun to try something different? In fact, an experiment on the drag force is conducted nearly 4000 times a day during the baseball season and you have free access to this PITCHf/x data!2
Re-examination of Mars Pathfinder parachute drag coefficient estimate
NASA Technical Reports Server (NTRS)
Desai, P.; Schofield, T.; Lisano, M.
2003-01-01
The Mars Exploration Rover (MER) mission utilizes the Mars Pathfinder (MPF) parachute design. The MPF parachute drag coefficient is a driver for the MER entry, descent, and landing (EDL) design. As a result, a good estimate of the performance of the MPF parachute at Mars is required.
Activity coefficients of chlorophenols in water at infinite dilution
Tabai, S.; Rogalski, M.; Solimando, R.; Malanowski, S.K.
1997-11-01
The total pressure of aqueous solutions of chlorophenols was determined by a ebulliometric total pressure method for the aqueous solutions of phenol, 2-chlorophenol, 3-chlorophenol, 4-chlorophenol, and 2,4-dichlorophenol in the temperature range from 40 to 90 C. The activity coefficients at infinite dilution and the Henry constants were derived.
Uptake coefficients for biosolids-amended dryland winter wheat
Technology Transfer Automated Retrieval System (TEKTRAN)
Biosolids regulations developed in the United States employed risk assessment impacts of trace element additions on plant uptake. The US Environmental Protection Agency adapted the uptake coefficient (ratio of plant concentration to quantity of element added) when developing limitations on selected...
Fitting Partially Nonlinear Random Coefficient Models as SEMs
ERIC Educational Resources Information Center
Harring, Jeffrey R.; Cudeck, Robert; du Toit, Stephen H. C.
2006-01-01
The nonlinear random coefficient model has become increasingly popular as a method for describing individual differences in longitudinal research. Although promising, the nonlinear model it is not utilized as often as it might be because software options are still somewhat limited. In this article we show that a specialized version of the model…
ROVIBRATIONAL QUENCHING RATE COEFFICIENTS OF HD IN COLLISIONS WITH He
Nolte, J. L.; Stancil, P. C.; Lee, T.-G.; Balakrishnan, N.; Forrey, R. C. E-mail: stancil@physast.uga.edu E-mail: naduvala@unlv.nevada.edu
2012-01-01
Along with H{sub 2}, HD has been found to play an important role in the cooling of the primordial gas for the formation of the first stars and galaxies. It has also been observed in a variety of cool molecular astrophysical environments. The rate of cooling by HD molecules requires knowledge of collisional rate coefficients with the primary impactors, H, He, and H{sub 2}. To improve knowledge of the collisional properties of HD, we present rate coefficients for the He-HD collision system over a range of collision energies from 10{sup -5} to 5 Multiplication-Sign 10{sup 3} cm{sup -1}. Fully quantum mechanical scattering calculations were performed for initial HD rovibrational states of j = 0 and 1 for v = 0-17 which utilized accurate diatom rovibrational wave functions. Rate coefficients of all {Delta}v = 0, -1, and -2 transitions are reported. Significant discrepancies with previous calculations, which adopted a small basis and harmonic HD wave functions for excited vibrational levels, were found for the highest previously considered vibrational state of v = 3. Applications of the He-HD rate coefficients in various astrophysical environments are briefly discussed.
SCALE Continuous-Energy Eigenvalue Sensitivity Coefficient Calculations
Perfetti, Christopher M.; Rearden, Bradley T.; Martin, William R.
2016-02-25
Sensitivity coefficients describe the fractional change in a system response that is induced by changes to system parameters and nuclear data. The Tools for Sensitivity and UNcertainty Analysis Methodology Implementation (TSUNAMI) code within the SCALE code system makes use of eigenvalue sensitivity coefficients for an extensive number of criticality safety applications, including quantifying the data-induced uncertainty in the eigenvalue of critical systems, assessing the neutronic similarity between different critical systems, and guiding nuclear data adjustment studies. The need to model geometrically complex systems with improved fidelity and the desire to extend TSUNAMI analysis to advanced applications has motivated the developmentmore » of a methodology for calculating sensitivity coefficients in continuous-energy (CE) Monte Carlo applications. The Contributon-Linked eigenvalue sensitivity/Uncertainty estimation via Tracklength importance CHaracterization (CLUTCH) and Iterated Fission Probability (IFP) eigenvalue sensitivity methods were recently implemented in the CE-KENO framework of the SCALE code system to enable TSUNAMI-3D to perform eigenvalue sensitivity calculations using continuous-energy Monte Carlo methods. This work provides a detailed description of the theory behind the CLUTCH method and describes in detail its implementation. This work explores the improvements in eigenvalue sensitivity coefficient accuracy that can be gained through the use of continuous-energy sensitivity methods and also compares several sensitivity methods in terms of computational efficiency and memory requirements.« less
Detection of community structure in networks based on community coefficients
NASA Astrophysics Data System (ADS)
Lu, Hu; Wei, Hui
2012-12-01
Determining community structure in networks is fundamental to the analysis of the structural and functional properties of those networks, including social networks, computer networks, and biological networks. Modularity function Q, which was proposed by Newman and Girvan, was once the most widely used criterion for evaluating the partition of a network into communities. However, modularity Q is subject to a serious resolution limit. In this paper, we propose a new function for evaluating the partition of a network into communities. This is called community coefficient C. Using community coefficient C, we can automatically identify the ideal number of communities in the network, without any prior knowledge. We demonstrate that community coefficient C is superior to the modularity Q and does not have a resolution limit. We also compared the two widely used community structure partitioning methods, the hierarchical partitioning algorithm and the normalized cuts (Ncut) spectral partitioning algorithm. We tested these methods on computer-generated networks and real-world networks whose community structures were already known. The Ncut algorithm and community coefficient C were found to produce better results than hierarchical algorithms. Unlike several other community detection methods, the proposed method effectively partitioned the networks into different community structures and indicated the correct number of communities.
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…
Consumptive Water Use and Crop Coefficients of Irrigated Sunflower
Technology Transfer Automated Retrieval System (TEKTRAN)
In semi-arid environments, the use of irrigation is necessary for sunflower production to reach its maximum potential. The aim of this study was to quantify the consumptive water use and crop coefficients of irrigated sunflower (Helianthus annuus L.) without soil water limitations during two growing...
Cautions in the Interpretation of the Partial Correlation Coefficient.
ERIC Educational Resources Information Center
Sachar, Jane
1980-01-01
The partial correlation coefficient is derived analytically under exemplary factor patterns. In these patterns, variables are described as an additive composition of a set of orthogonal factors, including general, common, and specific factors. Viewed in this framework, it is evident that the partial correlation may yield spurious results.…
A Note on a Geometric Interpretation of the Correlation Coefficient.
ERIC Educational Resources Information Center
Marks, Edmond
1982-01-01
An alternate geometric interpretation of the correlation coefficient to that given in most statistics texts for psychology and education is presented. This interpretation is considered to be more consistent with the statistical model for the data, and richer in geometric meaning. (Author)
Modeling Concordance Correlation Coefficient for Longitudinal Study Data
ERIC Educational Resources Information Center
Ma, Yan; Tang, Wan; Yu, Qin; Tu, X. M.
2010-01-01
Measures of agreement are used in a wide range of behavioral, biomedical, psychosocial, and health-care related research to assess reliability of diagnostic test, psychometric properties of instrument, fidelity of psychosocial intervention, and accuracy of proxy outcome. The concordance correlation coefficient (CCC) is a popular measure of…
Evaluation of the vertical turbulent diffusion coefficient of industrial emissions
NASA Astrophysics Data System (ADS)
Ryzhakova, N. K.; Pokrovskaya, E. A.; Babicheva, V. O.
2015-07-01
A method for determining the vertical turbulent diffusion coefficients of industrial emissions in complex terrain and with long exposure times has been considered. The method is based on the usage of the distribution of the polluting impurity measured along a certain direction from a point source. The measurements are carried out with moss-biomonitors for a CHP in Novosibirsk.
Linear force coefficients for squeeze-film dampers
Szeri, A.Z.; Giron-Duarte, A.; Raimondi, A.A.
1982-10-01
This paper presents a simplifed analysis of viscous squeeze-film damper behavior. It makes use of the notation of averaged inertia and calculates linear velocity and inertia coeffcients. These coefficients are shown to be accurate at practical values of the length/diameter ratio and the gap Reynolds number of the viscous damper.
Thermal coefficients of technology assimilation by natural systems
NASA Technical Reports Server (NTRS)
Mueller, R. F.
1971-01-01
Estimates of thermal coefficients of the rates of technology assimilation processes was made. Consideration of such processes as vegetation and soil recovery and pollution assimilation indicates that these processes proceed ten to several hundred times more slowly in earth's cold regions than in temperate regions. It was suggested that these differential assimilation rates are important data in planning for technological expansion in Arctic regions.
A Simple Measurement of the Sliding Friction Coefficient
ERIC Educational Resources Information Center
Gratton, Luigi M.; Defrancesco, Silvia
2006-01-01
We present a simple computer-aided experiment for investigating Coulomb's law of sliding friction in a classroom. It provides a way of testing the possible dependence of the friction coefficient on various parameters, such as types of materials, normal force, apparent area of contact and sliding velocity.
Temperature and pressure dependence of CO2 extinction coefficients.
NASA Technical Reports Server (NTRS)
Demore, W. B.; Patapoff, M.
1972-01-01
Results are presented of CO2 extinction coefficient measurements that were performed under conditions of temperature and pressure different from those used by previous investigators. The results show that, whereas pressure effects are generally negligible, temperature dependence is strong enough to invalidate the use of room temperature data for the Mars atmosphere.
Estimation of high temperature metal-silicate partition coefficients
NASA Technical Reports Server (NTRS)
Jones, John H.; Capobianco, Christopher J.; Drake, Michael J.
1992-01-01
It has been known for some time that abundances of siderophile elements in the upper mantle of the Earth are far in excess of those expected from equilibrium between metal and silicate at low pressures and temperatures. Murthy (1991) has re-examined this excess of siderophile element problem by estimating liquid metal/liquid silicate partition coefficients reduces from their measured values at a lower temperature, implying that siderophile elements become much less siderophilic at high temperatures. Murthy then draws the important conclusion that metal/silicate equilibrium at high temperatures can account for the abundances of siderophile elements in the Earth's mantle. Of course, his conclusion is critically dependent on the small values of the partition coefficients he calculates. Because the numerical values of most experimentally-determined partition coefficients increase with increasing temperature at both constant oxygen fugacity and at constant redox buffer, we think it is important to try an alternative extrapolation for comparison. We have computed high temperature metal/silicate partition coefficients under a different set of assumptions and show that such long temperature extrapolations yield values which are critically dependent upon the presumed chemical behavior of the siderophile elements in the system.
Transport coefficients for driven granular mixtures at low density
NASA Astrophysics Data System (ADS)
Khalil, Nagi; Garzó, Vicente
2013-11-01
The transport coefficients of a granular binary mixture driven by a stochastic bath with friction are determined from the inelastic Boltzmann kinetic equation. A normal solution is obtained via the Chapman-Enskog method for states near homogeneous steady states. The mass, momentum, and heat fluxes are determined to first order in the spatial gradients of the hydrodynamic fields, and the associated transport coefficients are identified. They are given in terms of the solutions of a set of coupled linear integral equations. As in the monocomponent case, since the collisional cooling cannot be compensated for locally by the heat produced by the external driving, the reference distributions (zeroth-order approximations) fi(0) (i=1,2) for each species depend on time through their dependence on the pressure and the temperature. Explicit forms for the diffusion transport coefficients and the shear viscosity coefficient are obtained by assuming the steady-state conditions and by considering the leading terms in a Sonine polynomial expansion. A comparison with previous results obtained for granular Brownian motion and by using a (local) stochastic thermostat is also carried out. The present work extends previous theoretical results derived for monocomponent dense gases [Garzó, Chamorro, and Vega Reyes, Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.87.032201 87, 032201 (2013)] to granular mixtures at low density.
Transport coefficients for driven granular mixtures at low density.
Khalil, Nagi; Garzó, Vicente
2013-11-01
The transport coefficients of a granular binary mixture driven by a stochastic bath with friction are determined from the inelastic Boltzmann kinetic equation. A normal solution is obtained via the Chapman-Enskog method for states near homogeneous steady states. The mass, momentum, and heat fluxes are determined to first order in the spatial gradients of the hydrodynamic fields, and the associated transport coefficients are identified. They are given in terms of the solutions of a set of coupled linear integral equations. As in the monocomponent case, since the collisional cooling cannot be compensated for locally by the heat produced by the external driving, the reference distributions (zeroth-order approximations) f(i)((0)) (i=1,2) for each species depend on time through their dependence on the pressure and the temperature. Explicit forms for the diffusion transport coefficients and the shear viscosity coefficient are obtained by assuming the steady-state conditions and by considering the leading terms in a Sonine polynomial expansion. A comparison with previous results obtained for granular Brownian motion and by using a (local) stochastic thermostat is also carried out. The present work extends previous theoretical results derived for monocomponent dense gases [Garzó, Chamorro, and Vega Reyes, Phys. Rev. E 87, 032201 (2013)] to granular mixtures at low density. PMID:24329253
The Impact of Eddy and Roughness Coefficients in Tsunami Modeling
NASA Astrophysics Data System (ADS)
Gayer, Gerhard; Leschka, Stefan
2010-05-01
Within the German-Indonesian Tsunami Early Warning System (GITEWS) project the German Research Centre Geesthacht (GKSS) and DHI-WASY investigated the impact of tsunamis in densely populated coastal areas of Indonesia. By performing hundreds of numerical simulations in three highly resolved (~10 m) priority areas, namely Kuta (Bali), Padang (West-Sumatra), and Cilacap (southern coast of Java), we established a scenario data base for the preparation of hazard and risk maps. In preparation for this work we examined the dependency of tsunami modeling results on eddy coefficients and Manning's roughness coefficients. The hydrodynamical models MIKE 21 HD and MIKE 21 BW were applied in 11 artificial set-ups with linearized bathymetries. By varying the coefficients over a large range of physically relevant values we found the impact on tsunami wave heights and run-up heights. For the scenario simulations we used MIKE 21 FM. We shortly present a method of preparing very detailed roughness maps (Manning coefficients assigned to 43 land-use classes) and show comparisons of simulations using this differentiated roughness information with simulations using constant values, the later a widely used approach.
Electron impact excitation coefficients for laboratory and astrophysical plasmas
NASA Technical Reports Server (NTRS)
Davis, J.; Kepple, P. C.; Blaha, M.
1976-01-01
Electron impact excitation rate coefficients have been obtained for a number of transitions in highly ionized ions of interest to astrophysical and laboratory plasmas. The calculations were done using the method of distorted waves. Results are presented for various transitions in highly ionized Ne, Na, Al, Si, A, Ca, Ni and Fe.
METHOD FOR MEASURING AIR-IMMISCIBLE LIQUID PARTITION COEFFICIENTS
The principal objective of this work was to measure nonaqueous phase liquid-air partition coefficients for various gas tracer compounds. Known amounts of trichloroethene (TCE) and tracer, as neat compounds, were introduced into glass vials and allowed to equilibrate. The TCE and ...
Assessing Dimensionality by Maximizing "H" Coefficient-Based Objective Functions
ERIC Educational Resources Information Center
van Abswoude, Alexandra A. H.; Vermunt, Jeroen K.; Hemker, Bas T.
2007-01-01
Mokken scale analysis can be used for scaling under nonparametric item response theory models. The results may, however, not reflect the underlying dimensionality of data. Various features of Mokken scale analysis--the H coefficient, Mokken scale conditions, and algorithms--may explain this result. In this article, three new H-based objective…
Determination of the Static Friction Coefficient from Circular Motion
ERIC Educational Resources Information Center
Molina-Bolívar, J. A.; Cabrerizo-Vílchez, M. A.
2014-01-01
This paper describes a physics laboratory exercise for determining the coefficient of static friction between two surfaces. The circular motion of a coin placed on the surface of a rotating turntable has been studied. For this purpose, the motion is recorded with a high-speed digital video camera recording at 240 frames s[superscript-1], and the…
Overall Heat and Mass Transfer Coefficient of Water Vapor Adsorption
NASA Astrophysics Data System (ADS)
Hamamoto, Yoshinori; Mori, Hideo; Godo, Masazumi; Miura, Kunio; Watanabe, Yutaka; Ishizawa, Toshihiko; Takatsuka, Takeshi
A fundamental investigation was performed to develop a compact and simple desiccant ventilation unit which is one of the main components of a novel energy saving air-conditioning system. Water vapor in the air is adsorbed and/or desorbed to be controlled the humidity of supply air through a unit of an adsorbent packed bed. A numerical simulation helps to understand the phenomena of heat and mass transfer in the bed. Overall transfer coefficients of them as properties for the simulation were estimated by performing both experiment and calculation. It was clarified that the transient overall equivalent heat and mass transfer does not strongly depend on the air flow rate through the packed bed, the averaged equivalent mass transfer is governed by surface and pore diffusion in a particle of adsorbent at low flow rate. Moreover, the coefficient during the adsorption process is slightly larger than desorption. An equation of the overall mass transfer coefficient is derived. It shows five times as large as the value estimated by experiment. Therefore, the correlation and fitting parameters are presented for prediction of the overall heat and mass transfer coefficients. The estimation accuracy was improved.
Visualising the Complex Roots of Quadratic Equations with Real Coefficients
ERIC Educational Resources Information Center
Bardell, Nicholas S.
2012-01-01
The roots of the general quadratic equation y = ax[superscript 2] + bx + c (real a, b, c) are known to occur in the following sets: (i) real and distinct; (ii) real and coincident; and (iii) a complex conjugate pair. Case (iii), which provides the focus for this investigation, can only occur when the values of the real coefficients a, b, and c are…
n-Alcohol/Water Partition Coefficients for Decachlorobiphenyl (PCB 209)
Measurements of n-octanol/water partition coefficients (Kow) for highly hydrophobic chemicals are extremely difficult and are rarely made, in part due to the large volumes of water typically needed to quantify these compounds in the aqueous phase. An extrapolation approach using ...
Measuring the Coefficient of Restitution Using a Digital Oscilloscope
ERIC Educational Resources Information Center
Wadhwa, Ajay
2009-01-01
We introduce a new method of determining the coefficient of restitution (COR) of a ball-surface combination by using the sound produced by the impact/collision of the ball with the surface. Using a digital electronic circuit, the electrical signal is amplified and fed to a digital storage oscilloscope through a relay circuit for measuring the time…
The Importance of Structure Coefficients in Regression Research.
ERIC Educational Resources Information Center
Thompson, Bruce; Borrello, Gloria M.
1985-01-01
Multiple regression analysis is frequently being employed in experimental and non-experimental research. However, when data include predictor variables that are correlated, some regression results can become difficult to interpret. This paper presents a study to provide a demonstration that structure coefficients may be useful in these cases.…
An experimental assembly for precise measurement of thermal accommodation coefficients.
Trott, Wayne M; Castañeda, Jaime N; Torczynski, John R; Gallis, Michael A; Rader, Daniel J
2011-03-01
An experimental apparatus has been developed to determine thermal accommodation coefficients for a variety of gas-surface combinations. Results are obtained primarily through measurement of the pressure dependence of the conductive heat flux between parallel plates separated by a gas-filled gap. Measured heat-flux data are used in a formula based on Direct Simulation Monte Carlo (DSMC) simulations to determine the coefficients. The assembly also features a complementary capability for measuring the variation in gas density between the plates using electron-beam fluorescence. Surface materials examined include 304 stainless steel, gold, aluminum, platinum, silicon, silicon nitride, and polysilicon. Effects of gas composition, surface roughness, and surface contamination have been investigated with this system; the behavior of gas mixtures has also been explored. Without special cleaning procedures, thermal accommodation coefficients for most materials and surface finishes were determined to be near 0.95, 0.85, and 0.45 for argon, nitrogen, and helium, respectively. Surface cleaning by in situ argon-plasma treatment reduced coefficient values by up to 0.10 for helium and by ∼0.05 for nitrogen and argon. Results for both single-species and gas-mixture experiments compare favorably to DSMC simulations. PMID:21456801
Temperature dependence of the Soret coefficient of ionic colloids.
Sehnem, A L; Figueiredo Neto, A M; Aquino, R; Campos, A F C; Tourinho, F A; Depeyrot, J
2015-10-01
The temperature dependence of the Soret coefficient S(T)(T) in electrostatically charged magnetic colloids is investigated. Two different ferrofluids, with different particles' mean dimensions, are studied. In both cases we obtain a thermophilic behavior of the Soret effect. The temperature dependence of the Soret coefficient is described assuming that the nanoparticles migrate along the ionic thermoelectric field created by the thermal gradient. A model based on the contributions from the thermoelectrophoresis and variation of the double-layer energy, without fitting parameters, is used to describe the experimental results of the colloid with the bigger particles. To do so, independent measurements of the ζ potential, mass diffusion coefficient, and Seebeck coefficient are performed. The agreement of the theory and the experimental results is rather good. In the case of the ferrofluid with smaller particles, it is not possible to get experimentally reliable values of the ζ potential and the model described is used to evaluate this parameter and its temperature dependence. PMID:26565244
Sensitivity of room acoustic parameters to changes in scattering coefficients
NASA Astrophysics Data System (ADS)
Rathsam, Jonathan; Wang, Lily M.
2001-05-01
This project uses the room acoustics computer modeling program, ODEON, to investigate the sensitivity of room acoustic parameters to changes in scattering coefficients. Particularly, the study is interested in determining if the results from certain room models are more sensitive to scattering coefficients than from other models, due to their geometry or absorption characteristics. If so, how can one quantify a model's susceptibility to being sensitive to scattering? Various models of three real spaces in Omaha, Nebraska are tested. The predicted reverberation, clarity, and spaciousness parameters are compared at various receiver locations, while the scattering coefficient of all surfaces is varied from 0 to 0.1, 0.3, 0.5, and 0.8. The resulting data are analyzed by frequency according to the (1) average absorption of the room; (2) magnitude variation of absorption within the room; (3) spatial distribution of absorption within the room; and (4) level of model detail. Initial results indicate that parameters studied may show more sensitivity to scattering coefficients in models that have a wider range of absorption values, more disparate distribution of absorption, and lower detail level. Various schemes that include these aspects are proposed for computing a model's sensitivity to changes in scattering.
PARTITION COEFFICIENTS FOR METALS IN SURFACE WATER, SOIL, AND WASTE
This report presents metal partition coefficients for the surface water pathway and for the source model used in the Multimedia, Multi-pathway, Multi-receptor Exposure and Risk Assessment (3MRA) technology under development by the U.S. Environmental Protection Agency. Partition ...
Recombination coefficients of O and N radicals on stainless steel
NASA Astrophysics Data System (ADS)
Singh, Harmeet; Coburn, J. W.; Graves, David B.
2000-09-01
Surface recombination coefficients of O and N radicals in pure O2 and N2 plasmas, respectively, have been estimated on the stainless steel walls of a low-pressure inductively coupled plasma reactor. The recombination coefficients are estimated using a steady state plasma model describing the balance between the volume generation of the radicals from electron-impact dissociation of the parent molecules, and the loss of the radicals due to surface recombination. The model uses radical and parent molecule number densities and the electron energy distribution function (EEDF) as input parameters. We have measured the radical number density using appearance potential mass spectrometry. The parent neutral number density is measured using mass spectrometry. The EEDF is measured using a Langmuir probe. The recombination coefficient of O radicals on stainless steel walls at approximately 330 K is estimated to be 0.17±0.02, and agrees well with previous measurements. The recombination coefficient of N radicals is estimated to be 0.07±0.02 on stainless steel at 330 K.
Recombination Coefficient Measurements of O and N radicals
NASA Astrophysics Data System (ADS)
Singh, Harmeet; Coburn, John; Graves, David
1999-10-01
Surface recombination of radicals in low-pressure high-density plasmas has direct influence on the neutral and ionic composition of the plasma. While, electron impact dissociation of molecules is the dominant mechanism for creation of radicals, the surface recombination of radicals is often expected to be the dominant loss mechanism. We have a combination of measurements and a model to determine the recombination coefficients of O and N, to O2 and N2, respectively on the stainless steel walls of our inductively coupled plasma chamber. The radial variation of the electron energy distribution function (EEDF) is measured using a tuned, cylindrical Langmuir probe. The number density of the molecular species is measured using line-of-sight modulated beam mass spectrometry. The mass spectrometer is differentially pumped in three stages to ensure a good beam to background signal ratio. The radical absolute number density is measured using appearance potential mass spectrometry with the aforementioned mass spectrometer. The recombination coefficient is calculated using a balance of the volume-generation and surface-loss rates of the radicals in the plasma. The generation rate of the radicals is calculated using the number density measurements of the parent molecule and the spatially resolved EEDFs. At approximately 330 K on stainless steel, the recombination coefficient for O is 0.16, and recombination coefficient for N is 0.07.
A Simple Method for Calculating Clebsch-Gordan Coefficients
ERIC Educational Resources Information Center
Klink, W. H.; Wickramasekara, S.
2010-01-01
This paper presents a simple method for calculating Clebsch-Gordan coefficients for the tensor product of two unitary irreducible representations (UIRs) of the rotation group. The method also works for multiplicity-free irreducible representations appearing in the tensor product of any number of UIRs of the rotation group. The generalization to…
Generic transport coefficients of a confined electrolyte solution.
Yoshida, Hiroaki; Mizuno, Hideyuki; Kinjo, Tomoyuki; Washizu, Hitoshi; Barrat, Jean-Louis
2014-11-01
Physical parameters characterizing electrokinetic transport in a confined electrolyte solution are reconstructed from the generic transport coefficients obtained within the classical nonequilibrium statistical thermodynamic framework. The electro-osmotic flow, the diffusio-osmotic flow, the osmotic current, as well as the pressure-driven Poiseuille-type flow, the electric conduction, and the ion diffusion are described by this set of transport coefficients. The reconstruction is demonstrated for an aqueous NaCl solution between two parallel charged surfaces with a nanoscale gap, by using the molecular dynamic (MD) simulations. A Green-Kubo approach is employed to evaluate the transport coefficients in the linear-response regime, and the fluxes induced by the pressure, electric, and chemical potential fields are compared with the results of nonequilibrium MD simulations. Using this numerical scheme, the influence of the salt concentration on the transport coefficients is investigated. Anomalous reversal of diffusio-osmotic current, as well as that of electro-osmotic flow, is observed at high surface charge densities and high added-salt concentrations. PMID:25493746
Generic transport coefficients of a confined electrolyte solution
NASA Astrophysics Data System (ADS)
Yoshida, Hiroaki; Mizuno, Hideyuki; Kinjo, Tomoyuki; Washizu, Hitoshi; Barrat, Jean-Louis
2014-11-01
Physical parameters characterizing electrokinetic transport in a confined electrolyte solution are reconstructed from the generic transport coefficients obtained within the classical nonequilibrium statistical thermodynamic framework. The electro-osmotic flow, the diffusio-osmotic flow, the osmotic current, as well as the pressure-driven Poiseuille-type flow, the electric conduction, and the ion diffusion are described by this set of transport coefficients. The reconstruction is demonstrated for an aqueous NaCl solution between two parallel charged surfaces with a nanoscale gap, by using the molecular dynamic (MD) simulations. A Green-Kubo approach is employed to evaluate the transport coefficients in the linear-response regime, and the fluxes induced by the pressure, electric, and chemical potential fields are compared with the results of nonequilibrium MD simulations. Using this numerical scheme, the influence of the salt concentration on the transport coefficients is investigated. Anomalous reversal of diffusio-osmotic current, as well as that of electro-osmotic flow, is observed at high surface charge densities and high added-salt concentrations.
Finding All Coefficients of a Polynomial with One Calculation.
ERIC Educational Resources Information Center
Satianov, Pavel
2003-01-01
The values of a polynomial with integer coefficients can be computed using a graphing calculator, but it is impossible to see the formula itself. Suggests finding this formula from numerical data and describes the unusual way to solve this problem with one calculation only. (Author/NB)
Velocity space scattering coefficients with applications in antihydrogen recombination studies
Chang; Ordonez
2000-12-01
An approach for calculating velocity space friction and diffusion coefficients with Maxwellian field particles is developed based on a kernel function derived in a previous paper [Y. Chang and C. A. Ordonez, Phys. Plasmas 6, 2947 (1999)]. The original fivefold integral expressions for the coefficients are reduced to onefold integrals, which can be used for any value of the Coulomb logarithm. The onefold integrals can be further reduced to standard analytical expressions by using a weak coupling approximation. The integral expression for the friction coefficient is used to predict a time scale that describes the rate at which a reflecting antiproton beam slows down within a positron plasma, while both species are simultaneously confined by a nested Penning trap. The time scale is used to consider the possibility of achieving antihydrogen recombination within the trap. The friction and diffusion coefficients are then used to derive an expression for calculating the energy transfer rate between antiprotons and positrons. The expression is employed to illustrate achieving antihydrogen recombination while taking into account positron heating by the antiprotons. The effect of the presence of an electric field on recombination is discussed. PMID:11138156
Divergent Diffusion Coefficients in Simulations of Fluids and Lipid Membranes.
Vögele, Martin; Hummer, Gerhard
2016-08-25
We investigate the dependence of single-particle diffusion coefficients on the size and shape of the simulation box in molecular dynamics simulations of fluids and lipid membranes. We find that the diffusion coefficients of lipids and a carbon nanotube embedded in a lipid membrane diverge with the logarithm of the box width. For a neat Lennard-Jones fluid in flat rectangular boxes, diffusion becomes anisotropic, diverging logarithmically in all three directions with increasing box width. In elongated boxes, the diffusion coefficients normal to the long axis diverge linearly with the height-to-width ratio. For both lipid membranes and neat fluids, this behavior is predicted quantitatively by hydrodynamic theory. Mean-square displacements in the neat fluid exhibit intermediate regimes of anomalous diffusion, with t ln t and t(3/2) components in flat and elongated boxes, respectively. For membranes, the large finite-size effects, and the apparent inability to determine a well-defined lipid diffusion coefficient from simulation, rationalize difficulties in comparing simulation results to each other and to those from experiments. PMID:27385207
High expansion coefficient glasses can be sealed to common metals
NASA Technical Reports Server (NTRS)
Camp, F. E.; Champman, J. W.; Hirayama, C.
1970-01-01
New series of high expansion coefficient glasses can be sealed by fusion onto hot surfaces of metals and alloys. Glasses have relatively low working temperatures, good chemical durability, and can be used in electrical insulators and feedthroughs to fluid or vacuum systems.
Solving Second-Order Differential Equations with Variable Coefficients
ERIC Educational Resources Information Center
Wilmer, A., III; Costa, G. B.
2008-01-01
A method is developed in which an analytical solution is obtained for certain classes of second-order differential equations with variable coefficients. By the use of transformations and by repeated iterated integration, a desired solution is obtained. This alternative method represents a different way to acquire a solution from classic power…
Trace element distribution coefficients in alkaline series. [Titanites; bitite
Lemarchand, F.; Villemant, B.; Calas, G.
1987-05-01
Mineral/groundmass partition coefficients for U, Th, Zr, Hf, Ta, Rb, REE, Co and Sc have been systematically measured in olivine, clinopyroxene, amphibole, biotite, Ti-magnetites, titanite, zircon and feldspars, in basaltic to trachytic lavas from alkaline series (Velay, Chaine des Puys: Massif Central, France and Fayal: Azores). Average partition coefficients are defined within the experimental uncertainty for limited compositional ranges (basalt-hawaiite, mugearites, benmoreite-trachyte), and are useful for trace element modelling. The new results for U, Th, Ta, Zr and Hf partition coefficients show contrasting behaviour. They can thus be used as ''key elements'' for identifying fractionating mineral phases in differentiation processes (e.g. Ta and Th for amphibole and mica). Partition coefficient may be calculated using the two-lattice model suggested by NIELSEN (1985). Such values show a considerably reduced chemical dependence in natural systems, relative to weight per cent D values. The residual variations may be accounted for by temperature or volatile influence. This calculation greatly enhances modelling possibilities using trace elements for comparing differentiation series as well as for predicting the behaviour of elements during magmatic differentiation.
Personal Dose Equivalent Conversion Coefficients For Photons To 1 GEV
Veinot, K. G.; Hertel, N. E.
2010-09-27
The personal dose equivalent, H{sub p}(d), is the quantity recommended by the International Commission on Radiation Units and Measurements (ICRU) to be used as an approximation of the protection quantity Effective Dose when performing personal dosemeter calibrations. The personal dose equivalent can be defined for any location and depth within the body. Typically, the location of interest is the trunk where personal dosemeters are usually worn and in this instance a suitable approximation is a 30 cm X 30 cm X 15 cm slab-type phantom. For this condition the personal dose equivalent is denoted as H{sub p,slab}(d) and the depths, d, are taken to be 0.007 cm for non-penetrating and 1 cm for penetrating radiation. In operational radiation protection a third depth, 0.3 cm, is used to approximate the dose to the lens of the eye. A number of conversion coefficients for photons are available for incident energies up to several MeV, however, data to higher energies are limited. In this work conversion coefficients up to 1 GeV have been calculated for H{sub p,slab}(10) and H{sub p,slab}(3) using both the kerma approximation and by tracking secondary charged particles. For H{sub p}(0.07) the conversion coefficients were calculated, but only to 10 MeV due to computational limitations. Additionally, conversions from air kerma to H{sub p,slab}(d) have been determined and are reported. The conversion coefficients were determined for discrete incident energies, but analytical fits of the coefficients over the energy range are provided. Since the inclusion of air can influence the production of secondary charged particles incident on the face of the phantom conversion coefficients have been determined both in vacuo and with the source and slab immersed within a sphere in air. The conversion coefficients for the personal dose equivalent are compared to the appropriate protection quantity, calculated according to the recommendations of the latest International Commission on
Upscaling the overland flow resistance coefficient for vegetated surfaces
NASA Astrophysics Data System (ADS)
Kim, J.; Ivanov, V. Y.; Katopodes, N.
2011-12-01
Estimation of hydraulic resistance for overland flows plays a crucial role in modeling rainfall-runoff, flood routing, and soil erosion processes. The resistance affects not only the accurate calculations of flow variables, but also the predictions of their derivative outcomes. In particular, resistance is highly spatially variable and controlled by local flow conditions and bed characteristics in hillslopes vegetated with patches of shrubs or woody plants. Numerous studies sought general ways of relating hydraulic resistance to roughness coefficients. A typical approach in determining the Darcy-Weisbach friction factor (f) is to relate it to the Reynolds number (Re). The case is applicable when flow completely submerges roughness elements. On the other hand, when the surface covered with stones, organic litter, or vegetation is not fully submerged by the flow, the f-Re relationship does not hold. Flow dimensionless variables other than Re may become predominant in determining the resistance. There is little information on how to determine the roughness coefficient of vegetated hillslopes of arbitrary scale as a function of flow variables and bed characteristics. Although many field or laboratory studies have attempted to address the problem, most of them were carried out in channels and over a limited range of possible flow conditions. The objective of this study was to investigate the upscaling properties of the resistance coefficient by resolving the details of the flow process at an extremely fine-scale. The domain was conceptualized as a sloped plane with a number of "obstacles" of centimeter scale (i.e., representing vegetation stems) that have infinitely long height. A number of simulations were designed with a numerical model resolving the two-dimensional form of Saint-Venant equations representing the propagation of dynamic wave. The simulations explored how the resistance coefficient varied with different vegetation covers, domain slopes, flow rates and
Seebeck Coefficient Metrology: Do Contemporary Protocols Measure Up?
NASA Astrophysics Data System (ADS)
Martin, Joshua; Wong-Ng, Winnie; Green, Martin L.
2015-06-01
Comparative measurements of the Seebeck coefficient are challenging due to the diversity of instrumentation and measurement protocols. With the implementation of standardized measurement protocols and the use of Standard Reference Materials (SRMs®), for example, the recently certified National Institute of Standards and Technology (NIST) SRM® 3451 ``Low Temperature Seebeck Coefficient Standard (10-390 K)'', researchers can reliably analyze and compare data, both intra- and inter-laboratory, thereby accelerating the development of more efficient thermoelectric materials and devices. We present a comparative overview of commonly adopted Seebeck coefficient measurement practices. First, we examine the influence of asynchronous temporal and spatial measurement of electric potential and temperature. Temporal asynchronicity introduces error in the absolute Seebeck coefficient of the order of ≈10%, whereas spatial asynchronicity introduces error of the order of a few percent. Second, we examine the influence of poor thermal contact between the measurement probes and the sample. This is especially critical at high temperature, wherein the prevalent mode of measuring surface temperature is facilitated by pressure contact. Each topic will include the comparison of data measured using different measurement techniques and using different probe arrangements. We demonstrate that the probe arrangement is the primary limit to high accuracy, wherein the Seebeck coefficients measured by the 2-probe arrangement and those measured by the 4-probe arrangement diverge with the increase in temperature, approaching ≈14% at 900 K. Using these analyses, we provide recommended measurement protocols to guide members of the thermoelectric materials community in performing more accurate measurements and in evaluating more comprehensive uncertainty limits.
Second-degree Stokes coefficients from multi-satellite SLR
NASA Astrophysics Data System (ADS)
Bloßfeld, Mathis; Müller, Horst; Gerstl, Michael; Štefka, Vojtěch; Bouman, Johannes; Göttl, Franziska; Horwath, Martin
2015-09-01
The long wavelength part of the Earth's gravity field can be determined, with varying accuracy, from satellite laser ranging (SLR). In this study, we investigate the combination of up to ten geodetic SLR satellites using iterative variance component estimation. SLR observations to different satellites are combined in order to identify the impact of each satellite on the estimated Stokes coefficients. The combination of satellite-specific weekly or monthly arcs allows to reduce parameter correlations of the single-satellite solutions and leads to alternative estimates of the second-degree Stokes coefficients. This alternative time series might be helpful for assessing the uncertainty in the impact of the low-degree Stokes coefficients on geophysical investigations. In order to validate the obtained time series of second-degree Stokes coefficients, a comparison with the SLR RL05 time series of the Center of Space Research (CSR) is done. This investigation shows that all time series are comparable to the CSR time series. The precision of the weekly/monthly and coefficients is analyzed by comparing mass-related equatorial excitation functions with geophysical model results and reduced geodetic excitation functions. In case of , the annual amplitude and phase of the DGFI solution agrees better with three of four geophysical model combinations than other time series. In case of , all time series agree very well to each other. The impact of on the ice mass trend estimates for Antarctica are compared based on CSR GRACE RL05 solutions, in which different monthly time series are used for replacing. We found differences in the long-term Antarctic ice loss of Gt/year between the GRACE solutions induced by the different SLR time series of CSR and DGFI, which is about 13 % of the total ice loss of Antarctica. This result shows that Antarctic ice mass loss quantifications must be carefully interpreted.
Bulk viscosity coefficients due to phonons in superfluid neutron stars
Manuel, Cristina; Tolos, Laura; Tarrús, Jaume E-mail: tarrus@ecm.ub.edu
2013-07-01
We calculate the three bulk viscosity coefficients as arising from the collisions among phonons in superfluid neutron stars. We use effective field theory techniques to extract the allowed phonon collisional processes, written as a function of the equation of state of the system. The solution of the dynamical evolution of the phonon number density allows us to calculate the bulk viscosity coefficients as function of the phonon collisional rate and the phonon dispersion law, which depends on the neutron pairing gap. Our method of computation is rather general, and could be used for different superfluid systems, provided they share the same underlying symmetries. We find that the behavior with temperature of the bulk viscosity coefficients is dominated by the contributions coming from the collinear regime of the 2↔3 phonon processes. For typical star radial pulsation frequencies of ω ∼ 10{sup 4}s{sup −1}, we obtain that the bulk viscosity coefficients at densities n∼>4n{sub 0} are within 10% from its static value for T∼<10{sup 9} K and for the case of strong neutron superfluidity in the core with a maximum value of the {sup 3}P{sub 2} gap above 1 MeV, while, otherwise, the static solution is not a valid approximation to the bulk viscosity coefficients. Compared to previous results from Urca and modified Urca reactions, we conclude that at T ∼ 10{sup 9}K phonon collisions give the leading contribution to the bulk viscosities in the core of the neutron stars, except for n ∼ 2n{sub 0} when the opening of the Urca processes takes place.
Absolute magnitudes and phase coefficients of trans-Neptunian objects
NASA Astrophysics Data System (ADS)
Alvarez-Candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Duffard, R.; Morales, N.; Santos-Sanz, P.; Thirouin, A.; Silva, J. S.
2016-02-01
Context. Accurate measurements of diameters of trans-Neptunian objects (TNOs) are extremely difficult to obtain. Thermal modeling can provide good results, but accurate absolute magnitudes are needed to constrain the thermal models and derive diameters and geometric albedos. The absolute magnitude, HV, is defined as the magnitude of the object reduced to unit helio- and geocentric distances and a zero solar phase angle and is determined using phase curves. Phase coefficients can also be obtained from phase curves. These are related to surface properties, but only few are known. Aims: Our objective is to measure accurate V-band absolute magnitudes and phase coefficients for a sample of TNOs, many of which have been observed and modeled within the program "TNOs are cool", which is one of the Herschel Space Observatory key projects. Methods: We observed 56 objects using the V and R filters. These data, along with those available in the literature, were used to obtain phase curves and measure V-band absolute magnitudes and phase coefficients by assuming a linear trend of the phase curves and considering a magnitude variability that is due to the rotational light-curve. Results: We obtained 237 new magnitudes for the 56 objects, six of which were without previously reported measurements. Including the data from the literature, we report a total of 110 absolute magnitudes with their respective phase coefficients. The average value of HV is 6.39, bracketed by a minimum of 14.60 and a maximum of -1.12. For the phase coefficients we report a median value of 0.10 mag per degree and a very large dispersion, ranging from -0.88 up to 1.35 mag per degree.
ERIC Educational Resources Information Center
Edwards, Lynne K.; Meyers, Sarah A.
Correlation coefficients are frequently reported in educational and psychological research. The robustness properties and optimality among practical approximations when phi does not equal 0 with moderate sample sizes are not well documented. Three major approximations and their variations are examined: (1) a normal approximation of Fisher's Z,…
NASA Astrophysics Data System (ADS)
Astrand, Par-Johan; Wirnhardt, Csaba; Biagini, Bruno; Weber, Michaela; Hellerman, Rani
2004-11-01
Since 1993, the EC DG Agriculture has promoted the use of "Controls with Remote Sensing" (CwRS) as appropriate control system within the Common Agricultural Policy (CAP). CwRS is considered suitable to check if agricultural area-based subsidies (yearly > 25 billion euro EC expenditure) are correctly granted. On the basis of the Council Regulation (EC) 165/94 and of the Commission Regulation (EC) 601/94, the Commission Services are required to centralize the satellite images acquisition. This task has been managed by the MARS Project at the JRC since 1999, where the whole controls activity is coordinated. The activity also includes the setting up of specifications, recommendations, performing Quality Controls (QC) and auditing of the selected contractors, and evaluation of new methods. Satellite image acquisition involves the control site definition within each Member State, and the subsequent chain of image acquisition over the defined sites including feasibility with image providers, acquisition, validation, ordering, delivery and final archiving of the imagery. In summary the 2004 years campaign involved a budget of approximately 3.2 M euro to cover some 150 High Resolution (HR) sites and 71 Very High Resolution (VHR) sites. The objective of this paper is to describe the CwRS image acquisition with emphasis on the Ikonos, Quickbird, and EROS A satellites for the 2004 years CwRS Campaign, to give preliminary results, recommendations and future trends.
NASA Astrophysics Data System (ADS)
Fang, L.
2015-12-01
Based on summarizing the research on the division of urban and rural areas, this paper defines the attributes of "cities" and "villages", and establishes a set of methods for the division of urban and rural areas based on multi-layer conditions and related indicator system. By using the method based on multi-layer condition, in combination with cumulative percentage and other mathematical methods, adopting the spatial comparison method by using Google Earth satellite images, the optimal threshold is decided through multi-condition screening and then the definitional standards are confirmed. This paper divides the urban and rural areas by selecting Xi'an city as the research area. The divided results compare to the results concluded by the National Bureau of Statistics of the People's Republic of China. It is found that the urbanization rate is reduced by 3.24%. Through overlapping comparison of satellite remote sensing images, it is proven that the feasibility and sophistication of the methods for the division of urban and rural areas through screening multiple conditions. Table Comparing the statistical methods and the research results. Discrepancy indicators Division results (cities and towns) by the Plan Division rresults by the National Bureau of Statistics (cities and towns) Number of census blocks 1257 1370 Total area of cities and towns 957.34km2 1579.21km2 Population 5429354 5698970 Urbanization Rate 65.36% 68.6%
Theoretical and observational determinations of the ionization coefficient of meteors
NASA Astrophysics Data System (ADS)
Jones, William
1997-07-01
We examine the problem of the determination of the ionization coefficient beta from both the theoretical and observational points of view. In the past, theoretical evaluations of beta in terms of the relevant scattering cross-sections have used the Massey-Sida formula, which we show to give results which are plainly incorrect. We derive an integral equation for beta and compare the results of its application to copper and iron with laboratory simulations. Agreement for the variation of the ionization coefficient with velocity is good. The ionization coefficient has been determined observationally by Verniani & Hawkins from a comparison of radar and visual observations, employing the luminous efficiency tau also obtained observationally by Verniani. However, this determination of tau would appear to be invalidated by fragmentation. There is good evidence that the radiation of cometary meteors is dominated by that of iron in the visual range, and we have accordingly re-analysed the data of Verniani & Hawkins using the luminous efficiency of iron obtained in simulation experiments. However, it is not possible to choose an iron concentration which gives agreement between the determination of the ionization coefficient by this means and its determination from the theoretical equation in terms of either scattering coefficients or simulation methods. The observational ionization coefficients are much lower than predicted by the present theory and we provisionally explain this as a consequence of transfer of charge from the meteoric ion to a molecule of the air. It is now possible for the meteoric atom to be re-ionized, but it is also possible at sufficiently high initial line densities for significant dissociative recombination of the electrons and nitrogen or oxygen to take place. This recombination will not take place in meteor trains simulated in an ionization chamber. We thus conclude that the present theory is limited to faint radio meteors at lower velocities (v<~35
Molar extinction coefficients of solutions of some organic compounds
NASA Astrophysics Data System (ADS)
Singh, Kulwant; Sandhu, G. K.; Lark, B. S.
2004-05-01
Molar extinction coefficients of aqueous solutions of some organic compounds, viz. formamide (CH_{3}NO), N-methylformamide (C_{2}H_{5}NO), NN-dimethylformamide (C_{3}H_{7}NO), NN-dimethylacetamide (C_{4}H_{9}NO), 1,4-dioxane (C_{4}H_{8}O_{2}), succinimide (C_{4}H_{5}NO_{2}) and solutions of acetamide (C_{2}H_{5}NO) and benzoic acid (C_{7}H_{6}O_{2}) in 1,4-dioxane (C_{4}H_{8}O_{2}) have been determined by narrow beam gamma-ray transmission method at 81, 356, 511, 662, 1173 and 1332 keV. The experimental values of mass attenuation coefficients of these compounds have been used to calculate effective atomic numbers and electron densities. The additivity rule earlier used for aqueous solution has been extended to non-aqueous (1,4-dioxane) solutions.
Absorption-coefficient-determination method for particulate materials.
Lindberg, J D; Douglass, R E; Garvey, D M
1994-07-01
A method is presented for determining the optical absorption coefficient, or the imaginary refractive index, of particulate material that has been collected from aerosols or hydrosols by means of filtration. The method, based on the Kubelka-Munk theory of diffuse reflectance, is nondestructive and requires no other knowledge of the sample than the amount present, the specific gravity, and an estimate of the real index of refraction. The theoretical development of the method is discussed along with an analysis of photometric and gravimetric errors. We test the method by comparing results obtained for powdered didymium glass with measurements made before the glass was crushed. An example of the method's application to the determination of the absorption coefficient of atmospheric dust at UV, visible, and near-IR wavelengths is also presented. PMID:20935789
Determination of the heat transfer coefficients in porous media
Kim, L.V.
1994-06-01
The process of transpiration cooling is considered. Methods are suggested for estimating the volumetric coefficient of heat transfer with the use of a two-temperature model and the surface heat transfer coefficient at entry into a porous wall. The development of new technology under conditions of increasing heat loads puts the search for effective methods of heat transfer enhancement in the forefront of theoretical investigations. One of the promising trends in the solution of this problem is the use of porous materials (PM) in the elements of power units. For thermal protection against convective or radiative heat fluxes, the method of transpiration cooling is successfully used. The mechanism operative in the thermal protection involves the injection of a coolant through a porous medium to produce a screen over the contour of a body in a flow for removing heat energy from the skeleton of the porous material.
Calculations of radar backscattering coefficient of vegetation-covered soils
NASA Technical Reports Server (NTRS)
Mo, T.; Schmugge, T. J.; Jackson, T. J. (Principal Investigator)
1983-01-01
A model for simulating the measured backscattering coefficient of vegetation-covered soil surfaces includes both coherent and incoherent components of the backscattered radar pulses from a rough sil surface. The effect of vegetation canopy scattering is also incorporated into the model by making the radar pulse subject to two-way attenuation and volume scattering when it passes through the vegetation layer. Model results agree well with the measured angular distributions of the radar backscattering coefficient for HH polarization at the 1.6 GHz and 4.75 GHz frequencies over grass-covered fields. It was found that the coherent scattering component is very important at angles near nadir, while the vegetation volume scattering is dominant at incident angles 30 degrees.
Verifying the Dependence of Fractal Coefficients on Different Spatial Distributions
Gospodinov, Dragomir; Marekova, Elisaveta; Marinov, Alexander
2010-01-21
A fractal distribution requires that the number of objects larger than a specific size r has a power-law dependence on the size N(r) = C/r{sup D}propor tor{sup -D} where D is the fractal dimension. Usually the correlation integral is calculated to estimate the correlation fractal dimension of epicentres. A 'box-counting' procedure could also be applied giving the 'capacity' fractal dimension. The fractal dimension can be an integer and then it is equivalent to a Euclidean dimension (it is zero of a point, one of a segment, of a square is two and of a cube is three). In general the fractal dimension is not an integer but a fractional dimension and there comes the origin of the term 'fractal'. The use of a power-law to statistically describe a set of events or phenomena reveals the lack of a characteristic length scale, that is fractal objects are scale invariant. Scaling invariance and chaotic behavior constitute the base of a lot of natural hazards phenomena. Many studies of earthquakes reveal that their occurrence exhibits scale-invariant properties, so the fractal dimension can characterize them. It has first been confirmed that both aftershock rate decay in time and earthquake size distribution follow a power law. Recently many other earthquake distributions have been found to be scale-invariant. The spatial distribution of both regional seismicity and aftershocks show some fractal features. Earthquake spatial distributions are considered fractal, but indirectly. There are two possible models, which result in fractal earthquake distributions. The first model considers that a fractal distribution of faults leads to a fractal distribution of earthquakes, because each earthquake is characteristic of the fault on which it occurs. The second assumes that each fault has a fractal distribution of earthquakes. Observations strongly favour the first hypothesis.The fractal coefficients analysis provides some important advantages in examining earthquake spatial
Robust stability of diamond families of polynomials with complex coefficients
NASA Technical Reports Server (NTRS)
Xu, Zhong Ling
1993-01-01
Like the interval model of Kharitonov, the diamond model proves to be an alternative powerful device for taking into account the variation of parameters in prescribed ranges. The robust stability of some kinds of diamond polynomial families with complex coefficients are discussed. By exploiting the geometric characterizations of their value sets, we show that, for the family of polynomials with complex coefficients and both their real and imaginary parts lying in a diamond, the stability of eight specially selected extreme point polynomials is necessary as well as sufficient for the stability of the whole family. For the so-called simplex family of polynomials, four extreme point and four exposed edge polynomials of this family need to be checked for the stability of the entire family. The relations between the stability of various diamonds are also discussed.
The nonlinear optical rectification coefficient in a hydrogenic quantum ring
NASA Astrophysics Data System (ADS)
Xie, Wenfang
2012-05-01
The second-order nonlinear optical rectification coefficient (ORC) associated with intersubband transitions in a hydrogenic quantum ring (QR) with a two-dimensional pseudopotential in the presence of an external magnetic field is theoretically investigated. Calculations are performed by using the perturbation method and the compact density-matrix approach within the effective mass approximation. Based on the computed energies and wave functions, we have investigated the effects of the hydrogenic impurity, an external magnetic field, the geometrical size and the chemical potential of the pseudopential on this coefficient. Our results show that the second-order nonlinear ORCs of a hydrogenic QR are strongly affected by the geometrical size and chemical potential of the pseudopential, the hydrogenic impurity and the external magnetic field.
A high absorption coefficient DL-MPP imitating owl skin
NASA Astrophysics Data System (ADS)
Guo, Lijun; Zhao, Zhan; Kong, Deyi; Wu, Shaohua; Du, Lidong; Fang, Zhen
2012-11-01
This paper proposes a high absorption coefficient micro-perforated panel (MPP) imitating owl skin structure for acoustic noise reduction. Compared to the traditional micro-perforated panel, this device has two unique characteristics-simulating the owl skin structure, its radius of perforated apertures even can be as small as 55μ, and its material is silicon and fabricated by micro-electrical mechanical system (MEMS) technology; So that its absorption coefficients of acoustic noise for normal incidence sound wave whose frequencies arrange from 1.5 kHz to 6.0 kHz are all above 0.8 which is the owl's hunts sensitivity frequency band. Double leaf MPP fabricated by MEMS technology is an absolutely bionic success in functional-imitation.
Measuring kinetic coefficients by molecular dynamics simulation of zone melting
NASA Astrophysics Data System (ADS)
Celestini, Franck; Debierre, Jean-Marc
2002-04-01
Molecular dynamics simulations are performed to measure the kinetic coefficient at the solid-liquid interface in pure gold. Results are obtained for the (111), (100), and (110) orientations. Both Au(100) and Au(110) are in reasonable agreement with the law proposed for collision-limited growth. For Au(111), stacking fault domains form, as first reported by Burke, Broughton, and Gilmer [J. Chem. Phys. 89, 1030 (1988)]. The consequence on the kinetics of this interface is dramatic: the measured kinetic coefficient is three times smaller than that predicted by collision-limited growth. Finally, crystallization and melting are found to be always asymmetrical and here again the effect is much more pronounced for the (111) orientation.
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
Measurement of airfoil heat transfer coefficients on a turbine stage
NASA Astrophysics Data System (ADS)
Dring, Robert P.; Blair, Michael F.; Joslyn, H. David
1987-10-01
A combined experimental and analytical program was conducted to examine the impact of a number of variables on the midspan heat transfer coefficients of the three airfoil rows in a one and one-half stage large scale turbine model. Variables included stator/rotor axial spacing, Reynolds number, turbine inlet turbulence, flow coefficient, relevant stator 1/stator 2 circumferential position, and rotation. Heat transfer data were acquired on the suction and pressure surfaces of the three airfoils. High density data were also acquired in the leading edge stagnation regions. Extensive documentation of the steady and unsteady aerodynamics was acquired. Finally, heat transfer data were compared with both a steady and an unsteady boundary layer analysis.
Measurement of airfoil heat transfer coefficients on a turbine stage
NASA Astrophysics Data System (ADS)
Dring, Robert P.; Blair, Michael F.; Joslyn, H. David
1986-10-01
The Primary basis for heat transfer analysis of turbine airfoils is experimental data obtained in linear cascades. These data were very valuable in identifying the major heat transfer and fluid flow features of a turbine airfoil. The first program objective is to obtain a detailed set of heat transfer coefficients along the midspan of a stator and a rotor in a rotating turbine stage. The data are to be compared to some standard analysis of blade boundary layer heat transfer which is in use today. A second program objective is to obtain a detailed set of heat transfer coefficients along the midspan of a stator located in the wake of an upstream turbine stage.
Discharge coefficients of holes angled to the flow direction
NASA Astrophysics Data System (ADS)
Hay, N.; Henshall, S. E.; Manning, A.
1992-06-01
In the cooling passages of gas turbine blades, branches are often angled to the direction of the internal flow. This is particularly the case with film cooling holes. Accurate knowledge of the discharge coefficient of such holes at the design stage is vital so that the holes are correctly sized thus avoiding wastage of coolant and the formation of hot spots on the blade. This paper describes an experimental investigation to determine the discharge coefficient of 30 deg inclined holes with various degrees of inlet radiusing and with the axis of the hole at various orientation angles to the direction of the flow. Results are given for nominal main flow Mach numbers of 0, 0.15 and 0.3. The effects of radiusing, orientation and cross flow Mach number are quantified in the paper, the general trends are described, and the criteria for optimum performance are identified.
Neural Network Prediction of New Aircraft Design Coefficients
NASA Technical Reports Server (NTRS)
Norgaard, Magnus; Jorgensen, Charles C.; Ross, James C.
1997-01-01
This paper discusses a neural network tool for more effective aircraft design evaluations during wind tunnel tests. Using a hybrid neural network optimization method, we have produced fast and reliable predictions of aerodynamical coefficients, found optimal flap settings, and flap schedules. For validation, the tool was tested on a 55% scale model of the USAF/NASA Subsonic High Alpha Research Concept aircraft (SHARC). Four different networks were trained to predict coefficients of lift, drag, moment of inertia, and lift drag ratio (C(sub L), C(sub D), C(sub M), and L/D) from angle of attack and flap settings. The latter network was then used to determine an overall optimal flap setting and for finding optimal flap schedules.
Multigrid methods for differential equations with highly oscillatory coefficients
NASA Technical Reports Server (NTRS)
Engquist, Bjorn; Luo, Erding
1993-01-01
New coarse grid multigrid operators for problems with highly oscillatory coefficients are developed. These types of operators are necessary when the characters of the differential equations on coarser grids or longer wavelengths are different from that on the fine grid. Elliptic problems for composite materials and different classes of hyperbolic problems are practical examples. The new coarse grid operators can be constructed directly based on the homogenized differential operators or hierarchically computed from the finest grid. Convergence analysis based on the homogenization theory is given for elliptic problems with periodic coefficients and some hyperbolic problems. These are classes of equations for which there exists a fairly complete theory for the interaction between shorter and longer wavelengths in the problems. Numerical examples are presented.
Second virial coefficient of a generalized Lennard-Jones potential.
González-Calderón, Alfredo; Rocha-Ichante, Adrián
2015-01-21
We present an exact analytical solution for the second virial coefficient of a generalized Lennard-Jones type of pair potential model. The potential can be reduced to the Lennard-Jones, hard-sphere, and sticky hard-sphere models by tuning the potential parameters corresponding to the width and depth of the well. Thus, the second virial solution can also regain the aforementioned cases. Moreover, the obtained expression strongly resembles the one corresponding to the Kihara potential. In fact, the Fk functions are the same. Furthermore, for these functions, the complete expansions at low and high temperature are given. Additionally, we propose an alternative stickiness parameter based on the obtained second virial coefficient. PMID:25612707
Determination of the static friction coefficient from circular motion
NASA Astrophysics Data System (ADS)
Molina-Bolívar, J. A.; Cabrerizo-Vílchez, M. A.
2014-07-01
This paper describes a physics laboratory exercise for determining the coefficient of static friction between two surfaces. The circular motion of a coin placed on the surface of a rotating turntable has been studied. For this purpose, the motion is recorded with a high-speed digital video camera recording at 240 frames s-1, and the videos are analyzed using Tracker video-analysis software, allowing the students to dynamically model the motion of the coin. The students have to obtain the static friction coefficient by comparing the centripetal and maximum static friction forces. The experiment only requires simple and inexpensive materials. The dynamics of circular motion and static friction forces are difficult for many students to understand. The proposed laboratory exercise addresses these topics, which are relevant to the physics curriculum.
Effects of vegetation canopy on the radar backscattering coefficient
NASA Technical Reports Server (NTRS)
Mo, T.; Blanchard, B. J.; Schmugge, T. J.
1983-01-01
Airborne L- and C-band scatterometer data, taken over both vegetation-covered and bare fields, were systematically analyzed and theoretically reproduced, using a recently developed model for calculating radar backscattering coefficients of rough soil surfaces. The results show that the model can reproduce the observed angular variations of radar backscattering coefficient quite well via a least-squares fit method. Best fits to the data provide estimates of the statistical properties of the surface roughness, which is characterized by two parameters: the standard deviation of surface height, and the surface correlation length. In addition, the processes of vegetation attenuation and volume scattering require two canopy parameters, the canopy optical thickness and a volume scattering factor. Canopy parameter values for individual vegetation types, including alfalfa, milo and corn, were also determined from the best-fit results. The uncertainties in the scatterometer data were also explored.
Computing connection coefficients of compactly supported wavelets on bounded intervals
Romine, C.H.; Peyton, B.W.
1997-04-01
Daubechies wavelet basis functions have many properties that make them desirable as a basis for a Galerkin approach to solving PDEs: they are orthogonal, with compact support, and their connection coefficients can be computed. The method developed by Latto et al. to compute connection coefficients does not provide the correct inner product near the endpoints of a bounded interval, making the implementation of boundary conditions problematic. Moreover, the highly oscillatory nature of the wavelet basis functions makes standard numerical quadrature of integrals near the boundary impractical. The authors extend the method of Latto et al. to construct and solve a linear system of equations whose solution provides the exact computation of the integrals at the boundaries. As a consequence, they provide the correct inner product for wavelet basis functions on a bounded interval.
Transport coefficients in diamond from ab-initio calculations
NASA Astrophysics Data System (ADS)
Löfâs, Henrik; Grigoriev, Anton; Isberg, Jan; Ahuja, Rajeev
2013-03-01
By combining the Boltzmann transport equation with ab-initio electronic structure calculations, we obtain transport coefficients for boron-doped diamond. We find the temperature dependence of the resistivity and the hall coefficients in good agreement with experimental measurements. Doping in the samples is treated via the rigid band approximation and scattering is treated in the relaxation time approximation. In contrast to previous results, the acoustic phonon scattering is the dominating scattering mechanism for the considered doping range. At room temperature, we find the thermopower, S, in the range 1-1.6 mV/K and the power factor, S2σ, in the range 0.004-0.16 μW /cm K2.