Relevant bibliographies by topics / Estimation of coefficient of variation

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Academic literature on the topic 'Estimation of coefficient of variation'

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Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Estimation of coefficient of variation"

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Ahmed, S. E. "Improved estimation of the coefficient of variation." Journal of Applied Statistics 21, no. 6 (January 1994): 565–73. http://dx.doi.org/10.1080/757584217.

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Ditlevsen, Susanne, and Petr Lansky. "Firing Variability Is Higher than Deduced from the Empirical Coefficient of Variation." Neural Computation 23, no. 8 (August 2011): 1944–66. http://dx.doi.org/10.1162/neco_a_00157.

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A convenient and often used summary measure to quantify the firing variability in neurons is the coefficient of variation (CV), defined as the standard deviation divided by the mean. It is therefore important to find an estimator that gives reliable results from experimental data, that is, the estimator should be unbiased and have low estimation variance. When the CV is evaluated in the standard way (empirical standard deviation of interspike intervals divided by their average), then the estimator is biased, underestimating the true CV, especially if the distribution of the interspike intervals is positively skewed. Moreover, the estimator has a large variance for commonly used distributions. The aim of this letter is to quantify the bias and propose alternative estimation methods. If the distribution is assumed known or can be determined from data, parametric estimators are proposed, which not only remove the bias but also decrease the estimation errors. If no distribution is assumed and the data are very positively skewed, we propose to correct the standard estimator. When defining the corrected estimator, we simply use that it is more stable to work on the log scale for positively skewed distributions. The estimators are evaluated through simulations and applied to experimental data from olfactory receptor neurons in rats.
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Guo, Huizhen, and Nabendu Pal. "On a Normal Mean with Known Coefficient of Variation." Calcutta Statistical Association Bulletin 54, no. 1-2 (March 2003): 17–30. http://dx.doi.org/10.1177/0008068320030102.

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This paper deals with estimation of θ when iid (independent and identically distributed) observations are available from a N( θ, cθ2) distribution where c > 0 is assumed to be known. Using the equivariance principle under the group of scale and direction transformations we first characterize the class of equivariant estimators of θ. We then investigate a few equivariant estimators, including the maximum likelihood estimator, in terms of standardized bias and standardized mean squared error.
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Sangngam, Prayad. "Ratio Estimators Using Coefficient of Variation and Coefficient of Correlation." Modern Applied Science 8, no. 5 (August 5, 2014): 70. http://dx.doi.org/10.5539/mas.v8n5p70.

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This paper introduces ratio estimators of the population mean using the coefficient of variation of study variable and auxiliary variables together with the coefficient of correlation between the study and auxiliary variables under simple random sampling and stratified random sampling. These ratio estimators are almost unbiased. The mean square errors of the estimators and their estimators are given. Sample size estimation in both sampling designs are presented. An optimal sample size allocation in stratified random sampling is also suggested. Based on theoretical study, it can be shown that these ratio estimators have smaller MSE than the unbiased estimators. Moreover, the empirical study indicates that these ratio estimators have smallest MSE compared to the existing ones.
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Şen, Zekai. "Instantaneous Runoff Coefficient Variation and Peak Discharge Estimation Model." Journal of Hydrologic Engineering 13, no. 4 (April 2008): 270–77. http://dx.doi.org/10.1061/(asce)1084-0699(2008)13:4(270).

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Viglione, A. "Confidence intervals for the coefficient of L-variation in hydrological applications." Hydrology and Earth System Sciences 14, no. 11 (November 11, 2010): 2229–42. http://dx.doi.org/10.5194/hess-14-2229-2010.

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Abstract. The coefficient of L-variation (L-CV) is commonly used in statistical hydrology, in particular in regional frequency analysis, as a measure of steepness for the frequency curve of the hydrological variable of interest. As opposed to the point estimation of the L-CV, in this work we are interested in the estimation of the interval of values (confidence interval) in which the L-CV is included at a given level of probability (confidence level). Several candidate distributions are compared in terms of their suitability to provide valid estimators of confidence intervals for the population L-CV. Monte-Carlo simulations of synthetic samples from distributions frequently used in hydrology are used as a basis for the comparison. The best estimator proves to be provided by the log-Student t distribution whose parameters are estimated without any assumption on the underlying parent distribution of the hydrological variable of interest. This estimator is shown to also outperform the non parametric bias-corrected and accelerated bootstrap method. An illustrative example of how this result can be used in hydrology is presented, namely in the comparison of methods for regional flood frequency analysis. In particular, it is shown that the confidence intervals for the L-CV can be used to assess the amount of spatial heterogeneity of flood data not explained by regionalization models.
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Thangjai, Warisa, Sa-Aat Niwitpong, and Suparat Niwitpong. "A Bayesian Approach for Estimation of Coefficients of Variation of Normal Distributions." Sains Malaysiana 50, no. 1 (January 31, 2021): 261–78. http://dx.doi.org/10.17576/jsm-2021-5001-25.

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The coefficient of variation is widely used as a measure of data precision. Confidence intervals for a single coefficient of variation when the data follow a normal distribution that is symmetrical and the difference between the coefficients of variation of two normal populations are considered in this paper. First, the confidence intervals for the coefficient of variation of a normal distribution are obtained with adjusted generalized confidence interval (adjusted GCI), computational, Bayesian, and two adjusted Bayesian approaches. These approaches are compared with existing ones comprising two approximately unbiased estimators, the method of variance estimates recovery (MOVER) and generalized confidence interval (GCI). Second, the confidence intervals for the difference between the coefficients of variation of two normal distributions are proposed using the same approaches, the performances of which are then compared with the existing approaches. The highest posterior density interval was used to estimate the Bayesian confidence interval. Monte Carlo simulation was used to assess the performance of the confidence intervals. The results of the simulation studies demonstrate that the Bayesian and two adjusted Bayesian approaches were more accurate and better than the others in terms of coverage probabilities and average lengths in both scenarios. Finally, the performances of all of the approaches for both scenarios are illustrated via an empirical study with two real-data examples.
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Badr, M., M. El-Shirbeny, M. El-Ansary, and M. Awad. "ESTIMATION OF CROP COEFFICIENT VARIATION THROUGH SATELLITE VNIR SPECTRAL DATA." Misr Journal of Agricultural Engineering 34, no. 2 (April 1, 2017): 829–42. http://dx.doi.org/10.21608/mjae.2017.96741.

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Rizvi, S. A. H., and R. Karan Singh. "On estimation of population mean using known coefficient of variation." Microelectronics Reliability 37, no. 5 (May 1997): 841–43. http://dx.doi.org/10.1016/s0026-2714(96)00113-8.

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Kanefuji, Koji, and Kosei Iwase. "Estimation for a scale parameter with known coefficient of variation." Statistical Papers 39, no. 4 (October 1998): 377–88. http://dx.doi.org/10.1007/bf02927100.

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Dissertations / Theses on the topic "Estimation of coefficient of variation"

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Ali-Adib, Tarif. "Estimation et lois de variation du coefficient de transfert de chaleur surface/ liquide en ébullition pour un liquide alimentaire dans un évaporateur à flot tombant." Phd thesis, AgroParisTech, 2008. http://pastel.archives-ouvertes.fr/pastel-00004544.

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Le coefficient de transfert de chaleur est nécessaire pour concevoir et dimensionner un évaporateur utilisé pour concentrer un liquide, tel que rencontré couramment dans les industries alimentaires. Le coefficient de transfert de chaleur le plus variable et le plus incertain est du coté produit, entre paroi et liquide, noté « h ». Il varie à la fois avec les propriétés thermo-physiques du liquide traité (ηL, σL, λL, ρL , CpL, ω, ...) et avec les paramètres du procédé (type d'évaporateur, φ ou Δθ, Γ (δ), P, rugosité de la surface, encrassement, etc), ces grandeurs étant définies dans le texte. Mais h est aussi lié au régime d'ébullition (nucléée ou non nucléée), et pour les évaporateurs de type « flot tombant », au régime d'écoulement laminaire ou turbulent, selon le nombre de Reynolds en film Ref. Nous avons étudié le cas des évaporateurs « à flot tombant », très utilisés dans les industries alimentaires pour concentrer le lait et les produits laitiers, les jus sucrés, les jus de fruits et légumes. L'objectif de notre travail était de définir une méthode fiable et économique pour évaluer a priori le coefficient de transfert de chaleur h coté liquide en ébullition, dans un évaporateur flot tombant. La première partie de la thèse a été consacrée à l'analyse bibliographique, qui a révélé une grande incertitude actuelle dans la prévision de h, sur la base des formules de la littérature, et des paramètres descripteurs proposés. La deuxième partie de la thèse a été de concevoir et construire un pilote utilisable pour estimer h, dans des conditions stationnaires connues et reproductibles. Dans la troisième partie, on présente les résultats et commente les lois de variations de h en fonction de la concentration de matière sèche du liquide XMS, de la température d'ébullition de liquide θL (ou P), du flux de chaleur φ ou (Δθ), et du débit massique de liquide par unité de périmètre de tube Γ, pour des propriétés de surface de chauffe fixées (ici, paroi en acier inoxydable poli Rs ≈ 0,8 μm). On commente l'effet sur h de chaque variable isolément, les autres étant maintenues constantes, ce qui confirme l'importance de la transition du régime non-nucléé au régime nucléé, cette transition variant avec la nature du liquide, sa concentration, et le flux de chaleur. On a montré la possibilité de modéliser un produit donné dans l'ensemble du domaine expérimental, où tous les paramètres peuvent varier simultanément, avec peu de coefficients, selon deux types d'équations (polynomiale et puissance). On a comparé le cas d'un liquide Newtonien (jus sucré) et non-Newtonien (solution de CMC dans l'eau). On a aussi observé le débit de mouillage critique Γcri et ses lois de variation. On a aussi démontré la possibilité de simplifier le plan d'expérience, aussi bien pour les liquides Newtoniens que non-Newtoniens, tout en gardant un coefficient de corrélation satisfaisant dans le domaine Γ > Γcri, cette modélisation pouvant servir de base de données produit pour l'ingénierie.
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Ali, Adib Tarif. "Estimation et lois de variation du coefficient de transfert de chaleur surface / liquide en ébullition pour un liquide alimentaire dans un évaporateur à flot tombant." Paris, AgroParisTech, 2008. http://pastel.paristech.org/4544/01/2008AGPT0007.pdf.

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Le coefficient de transfert de chaleur est nécessaire pour concevoir et dimensionner un évaporateur utilisé pour concentrer un liquide, tel que rencontré couramment dans les industries alimentaires. Le coefficient de transfert de chaleur le plus variable et le plus incertain est du côté produit, entre paroi et liquide, noté « h ». Il varie à la fois avec les propriétés thermo-physiques du liquide traité (ηL, σL, λL, ρL, CpL, ω,. . . ) et avec les paramètres du procédés (type d’évaporateur, φ ou Δθ, Γ (δ), P, rugosité de la surface, encrassement, etc), ces grandeurs étant définies dans le texte. Mais h est aussi lié au régime d’ébullition (nucléée ou non nucléée), et pour les évaporateurs de type « flot tombant », au régime d’écoulement laminaire ou turbulent, selon le nombre de Reynolds en film Ref. Nous avons étudié le cas des évaporateurs « à flot tombant », très utilisés dans les industries alimentaires pour concentrer le lait et les produits laitiers, les jus sucrés, les jus de fruits et légumes. L’objectif de notre travail était de définir une méthode fiable et économique pour évaluer a priori le coefficient de transfert de chaleur h côté liquide en ébullition dans un évaporateur flot tombant. La première partie de la thèse a été consacrée à l’analyse bibliographique, qui a révélé une grande incertitude actuelle dans la prévision de h, sur la base des formules de la littérature, et des paramètres descripteurs proposés. La deuxième partie de la thèse a été de concevoir et construire un pilote utilisable pour estimer h, dans des conditions stationnaires connues et reproductibles. Dans la troisième partie, on présente les résultats et commente les lois de variations de h en fonction de la concentration de matière sèche du liquide XMS, de la température d’ébullition de liquide θL (ou P), du flux de chaleur φ ou Δθ, et du débit massique de liquide par unité de périmètre de tube Γ, pour des propriétés de surface de chauffe fixées (ici, paroi en acier inoxydable poli Rs≈0,8 μm). On commente l’effet sur h de chaque variable isolément, les autres étant maintenues constantes, ce qui confirme l’importance de la transition du régime non nucléé au régime nucléé, cette transition variant avec la nature du liquide, sa concentration, et le flux de chaleur. On a aussi montré la possibilité de modéliser un produit donné dans l’ensemble du domaine expérimental, où tous les paramètres peuvent varier simultanément, avec peu de coefficients, selon deux types d’équations (polynomiale et puissance). On a comparé le cas d’un liquide Newtonien (jus sucré) et non Newtonien (solution de CMC dans l’eau). On a aussi observé le débit de mouillage critique Γcri et ses lois de variation. On a aussi démontré la possibilité de simplifier le plan d’expérience, aussi bien pour les liquides Newtoniens que non Newtoniens, tout en gardant un coefficient de corrélation satisfaisant le domaine Γ > Γcri, cette modélisation pouvant servir de base de données produit pour l’ingénierie
The heat transfer coefficient value is necessary to calculate the eat exchange surface when designing an evaporator, as currently used to concentrate liquids in food industry. The boiling heat transfer coefficient on the liquid side (h) is the most uncertain and: it depends on the liquid thermo-physical properties (ηL, σL, λL, ρL, CpL, ω,. . . ) as well as on the process conditions (type of evaporator, φ ou Δθ, Γ (δ), P, surface roughness, fouling, etc). Also, h depends on the boiling regime (non-nucleate or nucleate) and on the flow regime (laminar or turbulent) according to the film Reynolds number in falling film evaporators. The objective of our work is to define an economical and robust method to estimate h in a falling film evaporator which is common in food industry for concentrating fruit juice, milk and sugar solutions. The first section of our study was a bibliographic analysis which revealed the important dispersion among the h values calculated from the formulas cited in literature The second section was to design and construct a laboratory scale falling film evaporator (pilot) used to estimate h at stationary parameters conditions. The third section was to describe the results and variation laws of h versus the liquid dry matter concentration XMS, the boiling temperature θL, the heat flux φ or temperature gap Δθ and mass flow rate per unit of perimeter length Γ (with describing the critical mass flow for some solutions) noted that the nature of heating surface is kept constant during our work. We described the effect of each variable separately on h where, the other variables being kept constant. Also we studied the transition from non nucleate regime, which varied with the nature of liquid and the liquid concentration. Finally, we presented the experimental models for h = f (XMS,θL,φ,Γ) for a Newtonian liquid (sugar solution) and non Newtonian solution (CMC) that may be used for industrial evaporator design after validation. We have also proposed a method for the simplification or the experimental design
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Ekesiöö, Anton, and Andreas Ekhamre. "Safety formats for non-linear finite element analyses of reinforced concrete beams loaded to shear failure." Thesis, KTH, Betongbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231087.

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There exists several different methods that can be used to implement a level of safety when performing non-linear finite element analysis of a structure. These methods are called safety formats and they estimate safety by different means and formulas which are partly discussed further in this thesis. The aim of this master thesis is to evaluate a model uncertainty factor for one safety format method called the estimation of coefficient of variation method (ECOV) since it is suggested to be included in the next version of Eurocode. The ECOV method will also be compared with the most common and widely used safety format which is the partial factor method (PF). The first part of this thesis presents the different safety formats more thoroughly followed by a theoretical part. The theory part aims to provide a deeper knowledge for the finite element method and non-linear finite element analysis together with some beam theory that explains shear mechanism in different beam types. The study was conducted on six beams in total, three deep beams and three slender beams. The deep beams were previously tested in the 1970s and the slender beams were previously tested in the 1990s, both test series were performed in a laboratory. All beams failed due to shear in the experimental tests. A detailed description of the beams are presented in the thesis. The simulations of the beams were all performed in the FEM- programme ATENA 2D to obtain high resemblance to the experimental test. In the results from the simulations it could be observed that the ECOV method generally got a higher capacity than the PF method. For the slender beams both methods received rather high design capacities with a mean of about 82% of the experimental capacity. For the deep beams both method reached low design capacities with a mean of around 46% of the experimental capacity. The results regarding the model uncertainty factor showed that the mean value for slender beams should be around 1.06 and for deep beams it should be around 1.25.
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Vathanakhool, Khoollapath. "Estimation de la sécurité des poteaux en béton armé : compte tenu des variations aléatoires de leurs caractéristiques géométriques et mécaniques le long de leur ligne moyenne." Toulouse, INSA, 1987. http://www.theses.fr/1987ISAT0015.

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Pour etablir l'influence des variations le long du poteau dues au coffrage, a la position des armatures et au caracteristiques des materiaux, methode de calcul de la probabilite de ruine par simulation monte carlo, en tenant compte de la correlation entre troncons; definition statistique du troncon critique, en fonctions de parametres comme l'elancement et le pourcentage d'armatures
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Pellegrini, Caius Barcellos. "Precisão da estimativa da massa de forragem com discos medidores em pastagem natural." Universidade Federal de Santa Maria, 2006. http://repositorio.ufsm.br/handle/1/10700.

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The objective of this work was to evaluate precision of forage mass estimatings (FM) in natural pasture (NP) with discs. The treatments were three different discs areas, respectively 0.1; 0.2 and 0.3 m2 and each one combined with three weights of discs 5, 10 and 15 kg/m2. The experimental design was Completely Randomized Design with 50 replications, in an 3 x 3 factorial arrangement (3 disc areas x 3 weights of disc). The obtained results were submitted to regression analysis between height of disc and FM determined in each date of evaluation, area and weight of disc. From the mathematical models it were obtained the coefficient of residual variation (CV). Later, were adopted the analysis of variance method in Complete Blocks Design with seven replications of an factorial experiment (3 disc areas x 3 weights of disc) of periods. The relationship between three areas of discs associated with three weights and the CV of the measures gotten with discs were quadratic and positive. The disc area of 0.1 m2 and 5 weight kg/m2 presented smaller CV of the readings obtained with disc in the evaluated periods. With the increase the disc area, increased the CV for the weights of 5 and 10 kg/m2. The relations between the three weights and areas of discs and the CV were linear and positive. The smaller weight of disc of 5 kg/m2, associated with the area 0.1 m2 presented smaller CV. Weights added of 5 and 10 kg/m2 on the same disc area increased the CV in the evaluated periods. The relation between times of evaluation and the CV were linear and positive. The disc of smaller area, 0.1 m2 and 5 weight kg/m2, presented smaller CV for MF estimate in NP, therefore the most indicated to evaluate of MF in NP. The advance of the time of evaluation increased the CV of MF estimate in NP.
O objetivo do trabalho foi avaliar a precisão da estimativa da massa de forragem (MF) em pastagem natural (PN) com emprego de discos medidores. Os tratamentos foram três diferentes áreas de disco, respectivamente 0,1, 0,2 e 0,3 m2 e cada uma combinada com três pesos de disco 5, 10 e 15 kg/m2. O delineamento experimental foi inteiramente casualizado com 50 repetições, em um arranjo fatorial 3 x 3 (3 áreas de discos x 3 pesos de discos). Os resultados obtidos foram submetidos à análise de regressão entre altura do disco e MF determinada em cada data de avaliação, área e peso de disco. Dos modelos matemáticos obteve-se os coeficientes de variação residual (CV). Posteriormente, adotou-se o método de análise de variância em delineamento de blocos ao acaso com sete repetições de um experimento fatorial 3 x 3 (3 áreas de discos x 3 pesos de discos) para épocas avaliadas. As relações entre as combinações das três áreas dos discos associadas com os três pesos e o CV das medidas obtidas com disco foram quadráticas e positivas. A área de disco de 0,1 m2 e peso 5 kg/m2 apresentou o menor CV das leituras obtidas com disco nos períodos avaliados. À medida que aumentou a área de disco, aumentou o CV para os pesos de 5 e 10 kg/m2. As relações entre as combinações dos três pesos e áreas dos discos e o CV foram lineares e positivas. O menor peso de disco, de 5 kg/m2, associado à área de 0,1 m2 apresentou o menor CV. A relação entre épocas de avaliação e o CV foi linear e positiva. O disco de menor área 0,1 m2 e peso 5 kg/m2 apresentou o menor CV para a estimativa da MF da PN, sendo portanto o mais indicado para avaliar a MF da pastagem natural. O avanço da época de avaliação aumentou o CV na estimativa da MF da PN com discos.
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Chandler, I. D. "Vertical variation in diffusion coefficient within sediments." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/49612/.

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River ecosystems can be strongly in uenced by contaminants in the water column, in the pore water and attached to sediment particles. Current models [TGD, 2003] predict exposure to sediments based on equilibrium partitioning between dissolved and suspended-particle-sorbed phase in the water column despite numerous studies showing significant direct mass transfer across the sediment water interface. When exchange across the interface (hyporheic exchange) is included in modelling the diffusion coefficient is assumed to be constant with depth. The overall aims of this research were to quantify the vertical variation in diffusion coefficient below the sediment water interface and asses the use of a modified EROSIMESS-System (erosimeter) in the study of hyporheic exchange. The modified erosimeter and novel fibre optic uorometers measuring in-bed concentrations Rhodamine WT were employed in an experimental investigation. Five different diameter glass sphere beds (0.15 to 5.0mm) and five bed shear velocities (0.01 to 0.04m/s) allowed the vertical variation in diffusion coefficient to be quantified to a depth of 0.134m below the sediment water interface. The vertical variation in diffusion coefficient can be described using an exponential function that was found to be consistent for all the parameter combinations tested. This function, combined with the scaling relationship proposed by O'Connor and Harvey [2008] allows a prediction of the diffusion coefficient below the sediment water interface based on bed shear velocity, roughness height and permeability. 1D numerical diffusion model simulations using the exponential function compare favourably with the experimental data.
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曾達誠 and Tat-shing Tsang. "Statistical inference on the coefficient of variation." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31223503.

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Tsang, Tat-shing. "Statistical inference on the coefficient of variation /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21903980.

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Jung, Aekyung. "Interval Estimation for the Correlation Coefficient." Digital Archive @ GSU, 2011. http://digitalarchive.gsu.edu/math_theses/109.

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The correlation coefficient (CC) is a standard measure of the linear association between two random variables. The CC plays a significant role in many quantitative researches. In a bivariate normal distribution, there are many types of interval estimation for CC, such as z-transformation and maximum likelihood estimation based methods. However, when the underlying bivariate distribution is unknown, the construction of confidence intervals for the CC is still not well-developed. In this thesis, we discuss various interval estimation methods for the CC. We propose a generalized confidence interval and three empirical likelihood-based non-parametric intervals for the CC. We also conduct extensive simulation studies to compare the new intervals with existing intervals in terms of coverage probability and interval length. Finally, two real examples are used to demonstrate the application of the proposed methods.
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Achouri, Ali. "Cartes de contrôle pour le coefficient de variation." Nantes, 2014. http://archive.bu.univ-nantes.fr/pollux/show.action?id=7658d471-1a91-4022-9493-9f85b2a06a86.

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La Maîtrise Statistique des Procédés (MSP) est une méthode de suivi de la production basée sur les statistiques. Elle se base essentiellement sur les cartes de contrôle. Une hypothèse indispensable pour le développement des cartes de contrôle est que les paramètres μ0 et 0 du procédé sous-contrôle soient supposés constants. Mais, dans la pratique, il existe de nombreux procédés pour lesquels ces paramètres peuvent être variables. Dans cette optique, le recours au coefficient de variation est une alternative intéressante. Dans cette thèse, nous avons essayé de systématiquement proposer de nouvelles cartes de contrôle pour le coefficient de variation qui n’ont pas encore été traitées jusqu’à présent dans la littérature. Des cartes de contrôle avec règles supplémentaires, des cartes VSI, VSS sont proposées pour le coefficient de variation lorsque les paramètres sont connus. De plus, une carte de type Shewhart pour le coefficient de variation avec paramètres estimés est aussi proposée. Les performances de chacune des cartes ont été évaluées et les paramètres optimaux ont été systématiquement calculés. Une validation empirique des résultats a été élaborée dans des processus industriels existants
The Statistical Process Control (SPC) is an effective method based on statistics and used to monitor production. Control charts are the most important and primary tools of SPC. An indispensable assumption for the development of control charts is that the process parameters μ0 and 0 are assumed constant. In practice, the process parameters are often variables and the use of the coefficient of variation seems to be an interesting alternative. In this thesis, we will investigate the properties (in terms of the Run Length) of some control charts for the coefficient of variation in the case of known parameters, which have not been researched till now, such as Run Rules Chart, VSI Chart and VSS Chart. In addition, a Shewhart control chart for the coefficient of variation with estimated parameters is proposed. The performance of each control chart has been evaluated and the optimal parameters were systematically computed. An empirical validation of the results has been developed for real industrial processes
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Books on the topic "Estimation of coefficient of variation"

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Andersen, I. Digital instrumentation for damping coefficient estimation. Manchester: UMIST, 1995.

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Srivastava, M. S. Point and interval estimation of the interclass correlation coefficient. Toronto: University of Toronto, Dept. of Statistics, 1987.

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Knittel, Christopher R. Estimation of random coefficient demand models: Challenges, difficulties and warnings. Cambridge, MA: National Bureau of Economic Research, 2008.

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Keen, K. J. Asymptotic variance of the interclass correlation coefficient. [Toronto, Ont.]: University of Toronto, Department of Statistics, 1989.

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Jackson, Douglas E. Tool for studying the effects of range restriction in correlation coefficient estimation. Brooks Air Force Base, Tex: Air Force Systems Command, Air Force Human Resources Laboratory, 1990.

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Bederman, S. Samuel. Estimation methods in random coefficient regression for continuous and binary longitudinal data. Ottawa: National Library of Canada = Bibliothèque nationale du Canada, 1999.

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Bera, Anil K. Estimation of time-varying hedge ratios for corn and soybeans: BGARCH and random coefficient approaches. Urbana, Ill: Bureau of Economic and Business Research, University of Illinois at Urbana-Champaign, 1992.

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author, Thompson Simon G., ed. Mendelian randomization: Methods for using genetic variants in causal estimation. Boca Raton: CRC Press, Taylor & Francis Group, 2015.

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J, Mususa Ulimwengu. Estimation d'un coefficient correcteur de la structure de prix de revient en période de forte instabilité économique: Une note méthodologique. Kinshasa II, Zaïre: Centre d'analyse et de prospective économique, Institut de recherches économiques et sociales, Université de Kinshasa, 1995.

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Soni, N. K. Investment and output coefficient for engineers and engineering technicians and methodology for estimation of requirement of engineering degree and diploma holders. New Delhi: Institute of Applied Manpower Research, 1987.

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Book chapters on the topic "Estimation of coefficient of variation"

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Klobušiak, Matej, and Ján Pecár. "Simultaneous Efficient Estimation of Gravimetric Network Parameters and Variation Coefficients of Devices." In Geodesy and Physics of the Earth, 271–74. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-78149-0_63.

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Wang, Bo, and D. M. Titterington. "Variational Bayes Estimation of Mixing Coefficients." In Lecture Notes in Computer Science, 281–95. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/11559887_17.

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Stȩpniak, Czesław. "Coefficient of Variation." In International Encyclopedia of Statistical Science, 267. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-04898-2_177.

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Gooch, Jan W. "Coefficient of Variation." In Encyclopedic Dictionary of Polymers, 975. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_15183.

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Brown, Charles E. "Coefficient of Variation." In Applied Multivariate Statistics in Geohydrology and Related Sciences, 155–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-80328-4_13.

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Nahler, Gerhard. "coefficient of variation (CV)." In Dictionary of Pharmaceutical Medicine, 31. Vienna: Springer Vienna, 2009. http://dx.doi.org/10.1007/978-3-211-89836-9_235.

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Devroye, Luc, and Gábor Lugosi. "Total Variation." In Combinatorial Methods in Density Estimation, 38–46. New York, NY: Springer New York, 2001. http://dx.doi.org/10.1007/978-1-4613-0125-7_5.

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Sonoike, Kintake, and Sakae Katoh. "Variations of the Differential Extinction Coefficient of P-700 and Re-Estimation of Stoichiometry of Constituents in Photosystem I Reaction Center Complexes from Synechococcus elongatus." In Current Research in Photosynthesis, 1555–58. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0511-5_357.

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Han-Fu, Chen, and Lei Guo. "Coefficient Estimation for ARMAX Models." In Systems & Control: Foundations & Applications, 89–151. Boston, MA: Birkhäuser Boston, 1991. http://dx.doi.org/10.1007/978-1-4612-0429-9_4.

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Bertoluzza, Carlo, Rosa Casals, Gloria Naval, and Antonia Salas. "An Alternative to the Variation Coefficient." In Studies in Systems, Decision and Control, 45–54. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-73848-2_4.

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Conference papers on the topic "Estimation of coefficient of variation"

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Xing, Ruifang. "The Application of Coefficient of Variation Estimation in Reliability Study of Existing Structure." In 2018 2nd IEEE Advanced Information Management, Communicates, Electronic and Automation Control Conference (IMCEC). IEEE, 2018. http://dx.doi.org/10.1109/imcec.2018.8469617.

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Muraleedharan, Arun, Alexander Bertrand, and Jan D’hooge. "A linear least squares based estimation of spatial variation of the attenuation coefficient from ultrasound backscatter signals." In 2019 International Congress on Ultrasonics. ASA, 2019. http://dx.doi.org/10.1121/2.0001266.

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Kang, Eunho, Hyomoon Lee, Dongsu Kim, and Jongho Yoon. "A Study on Estimation Model of Incidence Factor of the Thermal Bridge Using In-Situ Measurement Infrared Thermography." In ASME 2021 15th International Conference on Energy Sustainability collocated with the ASME 2021 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/es2021-63750.

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Abstract Practical thermal bridge performance indicators (ITBs) of existing buildings may differ from calculated thermal bridge performance derived theoretically due to actual construction conditions, such as effect of irregular shapes and aging. To fill this gap in a practical manner, more realistic quantitative evaluation of thermal bridge at on-site needs to be considered to identify thermal behaviors throughout exterior walls and thus improve overall insulation performance of buildings. In this paper, the model of a thermal bridge performance indicator is developed based on an in-situ Infrared thermography method, and a case study is then carried out to evaluate thermal performance of an existing exterior wall using the developed model. For the estimation method in this study, the form of the likelihood function is used with the Bayesian method to constantly reflect the measured data. Subsequently, the coefficient of variation is applied to analyze required times for the assumed convergence. Results from the measurement for three days show that thermal bridge under the measurement has more heat losses, including 1.14 times, when compared to the non-thermal bridge. In addition, the results present that it takes about 40 hours to reach 1% of the variation coefficient. Comparison of the ITB estimated at coefficient of variation 1% (40 hours point) with the ITB estimated at end-of-experiment (72 hours point) results in 0.9% of a relative error.
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Mullick, Subhash C., Suresh Kumar, and Basant K. Chourasia. "Wind Induced Heat Transfer Coefficient From Flat Horizontal Surfaces Exposed to Solar Radiation." In ASME 2007 Energy Sustainability Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/es2007-36163.

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Upward heat losses have strong effect on the performance of flat plate solar collectors under different operating conditions. Suitable equations for estimation of top heat loss coefficient have already been proposed [1,2]. The top heat loss coefficient is a function of wind induced convective heat transfer coefficient in a flat plate solar collector. It is, therefore, important to choose appropriate values of this convective heat transfer coefficient for correct estimation of the top heat loss coefficient. Researchers [3–6] have suggested different wind speed based correlations for estimation of the wind induced convective heat transfer coefficient. These correlations give different values of wind heat transfer coefficient thus resulting in variation in values of the top heat loss coefficient of a solar collector under same operating conditions. In present study, an attempt has been made to measure and study the wind induced convective heat transfer coefficient from exposed flat horizontal surfaces in real wind. For this purpose, three unglazed test plates of similar construction and different sizes were employed. Experiments were conducted on the three test plates over rooftop of a building in built environment. From experimental data of the test plate, of size 925mm × 865mm × 2mm, a correlation between wind heat transfer coefficient and wind speed has been obtained by linear regression. The obtained correlation has also been compared with work of other researchers [3–6]. Results obtained from experimental data of the three test plates provide some interesting information about wind induced convective heat transfer coefficient.
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de Freitas Rachid, Felipe Bastos, Jose´ Henrique Carneiro de Araujo, and Renan Martins Baptista. "The Influence of Pipeline Diameter Variation on the Mixing Volume in Batch Transfers." In 2002 4th International Pipeline Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ipc2002-27168.

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Presented in this paper is a new model for estimating mixing volumes arising in batch transfers in multiproduct pipelines, when variations of the line diameter as well as injection and/or withdrawal of products are present. Besides these novel features, the model incorporates the flow rate variation with time and the use of a more precise effective dispersion coefficient, which is considered to depend on the concentration. The governing equations of the model form a non-linear initial-value problem that is solved by using a predictor-corrector finite difference method. A comparison among several cases studied reveals that the pipeline diameter variation can effectively reduce the amount of mixing volume when compared to a similar transfer carried out in a constant diameter line.
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Ruiz, Rafael O., and Sergio E. Diaz. "Effect of Uncertainties in the Estimation of Dynamic Coefficients on Tilting Pad Journal Bearings." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67252.

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It has been identified that small variations in the pad clearance and preload of a Tilting Pad Journal Bearing lead to important variations in their dynamic coefficients. Although this variation trend is already identified, a more robust statistical analysis is required in order to identify more general tendencies and quantify it. This work presents a framework that helps to identify the relation between the manufacturing tolerance of the bearing (reflected in the pad clearance and preload) and the expected variations on the dynamic coefficients. The procedure underlies the adoption of a surrogate model (based on Kriging interpolation) trained by any deterministic model available to predict dynamic coefficients. The pad clearance and preload are considered uncertain parameters defined by a proper probability density function. All statistical quantities are obtained using stochastic simulation, specifically adopting a Monte Carlo simulation employing the surrogate model. The framework is illustrated through the study of a five pad bearing.
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Zhu, Qilun, Robert Prucka, Shu Wang, Michael Prucka, and Hussein Dourra. "Control Oriented Modelling of Engine IMEP Variation." In ASME 2016 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icef2016-9342.

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Engine cycle-by-cycle combustion variation is a potential source of emissions and drivability issues in automobiles, and has become an important concern for engine control engineers. The nature of turbulent combustion in IC engines means that combustion variations cannot be eliminated completely. Furthermore, it is inevitable for the engine to run at conditions with high combustion variations in most vehicle applications. For example, during gear shifts spark timing can be changed dramatically to help track the fast transitions of torque demand, often resulting in high Coefficient of Variation in Indicated Mean Effective Pressure (COV of IMEP). Under these circumstances, the control engineers have to weigh between combustion variation and other performance demands (i.e. fast torque tracking). An accurate online estimation of COV of IMEP can be beneficial to this process. A calibrated map of COV of IMEP versus engine operating conditions can be an option for engines with few control actuators. As the number of control actuators increases, combustion variation modelling using inputs with physical representations becomes favorable due to the potential for reduced calibration effort. However, since COV of IMEP is a stochastic variable describing the distribution of IMEP output, it can only be modelled empirically. This research proposes a control-oriented real-time COV of IMEP model based on an Artificial Neural Network (ANN) and inputs from turbulent combustion research. The effects of premixed turbulent combustion variation are analyzed with flame regime analysis in this research after a brief introduction of the experimental setup and engine information. In-cylinder thermodynamics are then evaluated to reveal how the changes of heat release transform into the variation of cylinder pressure, producing COV of IMEP. A range of model input parameters are assessed to determine the set that produces the most accurate prediction of IMEP variation with minimal computational requirements. An Artificial Neural Network (ANN) is applied to capture the nonlinear coupled correlations between COV of IMEP and model inputs. The ANN is combined with a regression pretreatment to reduce network size and improve extrapolation stability. This computationally efficient single-layer three-neuron ANN COV of IMEP model achieved 0.29% normalized Root Mean Square Error (RMSE). Dynamometer tests show that the model performs well outside the training region.
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Shin, Kwang-Keun. "Real-Time Vehicle Dynamics Parameter Estimation." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-79224.

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Vehicle dynamics parameters such as understeer coefficient are very important factors to determine the stability and dynamic handling behavior of a vehicle. These parameters vary during the lifetime of a vehicle according to different loading, tire pressure/wear or vehicle-to-vehicle variations of suspension characteristics, etc. The parameter deviations from nominal values may cause performance degradation of chassis/vehicle control systems, which is often designed based on the nominal values. Therefore, if the vehicle dynamics parameters can be estimated and monitored in real-time, the performance of chassis/vehicle control systems could be further enhanced. This paper presents a real-time vehicle dynamics parameter estimation method that estimates vehicle understeer coefficient and front/rear cornering compliances. The algorithm is implemented using Simulink, and analyzed, and validated using VehSim, which is a PC windows-based vehicle simulation software for vehicle dynamics controls and integration. The simulation results show that the developed algorithm is well capable of estimating vehicle dynamics parameters of VehSim, and, therefore, is highly feasible for in-vehicle applications.
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Petricic, Martin, and Alaa E. Mansour. "Estimation of the Long Term Correlation Coefficients by Simulation." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20637.

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This paper proposes a simulation method for obtaining the estimate of the long term correlation coefficients between different low-frequency wave-induced loads acting on a ship hull. They are essential part of the load combination procedures in design and strength evaluations. Existing theory is limited to linear time-invariant systems with weakly stationary stochastic inputs such as waves during a single sea state (short-term). The simulation treats the non-stationary wave elevations during the ship’s entire life (long-term) as a sequence of different stationary Gaussian stochastic processes. Different sea states (HS, T0, Wave Direction) are sampled, using rejection sampling, from the joint probability density functions fitted to every Marsden zone on the ship’s route. The time series of the loads are simulated from the load spectra for each sea state, including the effects of loading condition, heading, speed, seasonality and voluntary as well as involuntary speed reduction. The estimates of the correlation coefficients are then calculated from these time series. The simulation time can be significantly reduced (to the order of seconds rather than hours and days) by introducing the seasonal variations into a single voyage. It is proven that the estimate of the correlation coefficient, obtained by simulating only a single voyage, approaches the true correlation coefficient in probability as the number of simulated load values increases. The simulation method can also be used for finding the long-term exceedance probabilities of the peak values of individual loads as well as for analyzing various load combinations (linear and nonlinear). Related concepts and limitations of this method are demonstrated by an example of a containership operating between Boston, MA and Southampton, UK.
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Chyu, M. K., Y. C. Hsing, T. I. P. Shih, and V. Natarajan. "Heat Transfer Contributions of Pins and Endwall in Pin-Fin Arrays: Effects of Thermal Boundary Condition Modeling." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-175.

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Short pin-fin arrays are often used for cooling turbine airfoils, particularly near the trailing edge. An accurate heat transfer estimation from a pin-fin array should account for the total heat transfer over the entire wetted surface which includes the pin surfaces and uncovered end walls. One design question frequently raised is the actual magnitudes of heat transfer coefficients on both pins and endwalls. Results from earlier studies have led to different and often contradicting conclusions. This variation, in part, is caused by imperfect or unrealistic thermal boundary conditions prescribed in the individual test models. Either pins or endwalls, but generally not both, were heated in those previous studies. Using a mass transfer analogy based on the naphthalene sublimation technique, the present experiment is capable of revealing the individual heat transfer contributions from pins and endwalls with the entire wetted surface thermally active. The particular pin-fin geometry investigated, S/D = X/D = 2.5 and H/D = 1.0, is considered to be one of the optimal array arrangement for turbine airfoil cooling. Both inline and staggered arrays with the identical geometric parameters are studied for 5,000 ≤ Re ≤ 25,000. The present results reveal that the general trends of the row-resolved heat transfer coefficients on either pins or endwalls are somewhat insensitive to the nature of thermal boundary conditions prescribed on the test surface. However, the actual magnitudes of heat transfer coefficients can be substantially different, due to variations in the flow bulk temperature. The present study also concludes that the pins have consistently 10 to 20% higher heat transfer coefficient than the endwalls. However, such a difference in heat transfer coefficient imposes very insignificant influence on the overall array-averaged heat transfer, since the wetted area of the uncovered endwalls is nearly four times greater than that of the pins.
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Reports on the topic "Estimation of coefficient of variation"

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Graham, Bryan, and James Powell. Identification and Estimation of 'Irregular' Correlated Random Coefficient Models. Cambridge, MA: National Bureau of Economic Research, November 2008. http://dx.doi.org/10.3386/w14469.

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Knittel, Christopher, and Konstantinos Metaxoglou. Estimation of Random Coefficient Demand Models: Challenges, Difficulties and Warnings. Cambridge, MA: National Bureau of Economic Research, June 2008. http://dx.doi.org/10.3386/w14080.

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Jackson, Douglas E., and Malcolm J. Ree. Tool for Studying the Effects of Range Restriction in Correlation Coefficient Estimation. Fort Belvoir, VA: Defense Technical Information Center, July 1990. http://dx.doi.org/10.21236/ada224035.

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Nishida, Kenji, Tetsuya Kaneko, Yoichi Takahashi, and Koji Aoki. Estimation of Indicated Mean Effective Pressure Using Crankshaft Angular Velocity Variation. Warrendale, PA: SAE International, November 2011. http://dx.doi.org/10.4271/2011-32-0510.

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Stock, James, and Mark Watson. Asymptotically Median Unbiased Estimation of Coefficient Variance in a Time Varying Parameter Model. Cambridge, MA: National Bureau of Economic Research, August 1996. http://dx.doi.org/10.3386/t0201.

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Wiemann, Michael C., and G. Bruce Williamson. Wood Specific Gravity Variation with Height and Its Implications for Biomass Estimation. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory, 2014. http://dx.doi.org/10.2737/fpl-rp-677.

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Over, Thomas, Riki Saito, Andrea Veilleux, Padraic O’Shea, Jennifer Sharpe, David Soong, and Audrey Ishii. Estimation of Peak Discharge Quantiles for Selected Annual Exceedance Probabilities in Northeastern Illinois. Illinois Center for Transportation, June 2016. http://dx.doi.org/10.36501/0197-9191/16-014.

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This report provides two sets of equations for estimating peak discharge quantiles at annual exceedance probabilities (AEPs) of 0.50, 0.20, 0.10, 0.04, 0.02, 0.01, 0.005, and 0.002 (recurrence intervals of 2, 5, 10, 25, 50, 100, 200, and 500 years, respectively) for watersheds in Illinois based on annual maximum peak discharge data from 117 watersheds in and near northeastern Illinois. One set of equations was developed through a temporal analysis with a two-step least squares-quantile regression technique that measures the average effect of changes in the urbanization of the watersheds used in the study. The resulting equations can be used to adjust rural peak discharge quantiles for the effect of urbanization, and in this study the equations also were used to adjust the annual maximum peak discharges from the study watersheds to 2010 urbanization conditions. The other set of equations was developed by a spatial analysis. This analysis used generalized least-squares regression to fit the peak discharge quantiles computed from the urbanization-adjusted annual maximum peak discharges from the study watersheds to drainage-basin characteristics. The peak discharge quantiles were computed by using the Expected Moments Algorithm following the removal of potentially influential low floods defined by a multiple Grubbs-Beck test. To improve the quantile estimates, regional skew coefficients were obtained from a newly developed regional skew model in which the skew increases with the urbanized land use fraction. The skew coefficient values for each streamgage were then computed as the variance-weighted average of at-site and regional skew coefficients. The drainage-basin characteristics used as explanatory variables in the spatial analysis include drainage area, the fraction of developed land, the fraction of land with poorly drained soils or likely water, and the basin slope estimated as the ratio of the basin relief to basin perimeter. This report also provides: (1) examples to illustrate the use of the spatial and urbanization-adjustment equations for estimating peak discharge quantiles at ungaged sites and to improve flood-quantile estimates at and near a gaged site; (2) the urbanization-adjusted annual maximum peak discharges and peak discharge quantile estimates at streamgages from 181 watersheds including the 117 study watersheds and 64 additional watersheds in the study region that were originally considered for use in the study but later deemed to be redundant. The urbanization-adjustment equations, spatial regression equations, and peak discharge quantile estimates developed in this study will be made available in the web-based application StreamStats, which provides automated regression-equation solutions for user-selected stream locations. Figures and tables comparing the observed and urbanization-adjusted peak discharge records by streamgage are provided at http://dx.doi.org/10.3133/sir20165050 for download.
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Manninen, Terhikki, and Pauline Stenberg. Influence of forest floor vegetation on the total forest reflectance and its implications for LAI estimation using vegetation indices. Finnish Meteorological Institute, 2021. http://dx.doi.org/10.35614/isbn.9789523361379.

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Recently a simple analytic canopy bidirectional reflectance factor (BRF) model based on the spectral invariants theory was presented. The model takes into account that the recollision probability in the forest canopy is different for the first scattering than the later ones. Here this model is extended to include the forest floor contribution to the total forest BRF. The effect of the understory vegetation on the total forest BRF as well as on the simple ratio (SR) and the normalized difference (NDVI) vegetation indices is demonstrated for typical cases of boreal forest. The relative contribution of the forest floor to the total BRF was up to 69 % in the red wavelength range and up to 54 % in the NIR wavelength range. Values of SR and NDVI for the forest and the canopy differed within 10 % and 30 % in red and within 1 % and 10 % in the NIR wavelength range. The relative variation of the BRF with the azimuth and view zenith angles was not very sensitive to the forest floor vegetation. Hence, linear correlation of the modelled total BRF and the Ross-thick kernel was strong for dense forests (R2 > 0.9). The agreement between modelled BRF and satellite-based reflectance values was good when measured LAI, clumping index and leaf single scattering albedo values for a boreal forest were used as input to the model.
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Peitz, David, and Naomi Reibold. White-tailed deer monitoring at Arkansas Post National Memorial, Arkansas: 2005–2020 trend report. Edited by Tani Hubbard. National Park Service, April 2021. http://dx.doi.org/10.36967/nrr-2285087.

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From 16 years (2005–2020) of monitoring trends in white-tailed deer within a defined survey area of Arkansas Post National Memorial, we have been able to demonstrate both population declines and recoveries. The adjusted count of deer had a seven-fold increase between 2007 and 2011 following a two-year decline and a three-fold increase between 2017 and 2019 following a six-year decline. Overall, the deer population has declined slightly, averaging a 0.5% reduction in herd size annually. The number of deer in the survey area ranged from 16.77 ± 21.26 (mean + 95% CI) individuals/km2 in 2007 to 118.95 ± 39.03 individuals/km2 in 2011. The amount of visible area surveyed each year varied between 0.25 and 0.47 km2 (coefficient of variation = 16.47%). If the white-tailed deer population becomes too large, this poses several problems for Arkansas Post National Memorial. First, it adds a level of complexity to implementing active natural resource management critical to preventing the cultural landscapes of Arkansas Post National Memorial from changing into something that has little resemblance to the historical character of the park. Deer deferentially browse native vegetation over exotic vegetation, thus promoting the spread of exotic species, and the success of tree planting can be curtailed by heavy deer browsing. Second, controlling deer related disease, some of which can affect domestic livestock and human health in and around the park, becomes increasingly difficult when there are more deer. Third, as additional ancillary data suggests, the largely unreported and costly deer-vehicle collisions in and around Arkansas Post National Memorial have the potential to increase if the deer populations grow.
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