Relevant bibliographies by topics / Compound K-distribution

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Compound K-distribution'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Compound K-distribution"

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Koutras, Markos V., and Serkan Eryilmaz. "Compound Geometric Distribution of Order k." Methodology and Computing in Applied Probability 19, no. 2 (February 4, 2016): 377–93. http://dx.doi.org/10.1007/s11009-016-9482-y.

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Lee, Sang-Hyeok, Sangjin Ahn, and Mi-hyun Kim. "Comparing a Query Compound with Drug Target Classes Using 3D-Chemical Similarity." International Journal of Molecular Sciences 21, no. 12 (June 12, 2020): 4208. http://dx.doi.org/10.3390/ijms21124208.

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3D similarity is useful in predicting the profiles of unprecedented molecular frameworks that are 2D dissimilar to known compounds. When comparing pairs of compounds, 3D similarity of the pairs depends on conformational sampling, the alignment method, the chosen descriptors, and the similarity coefficients. In addition to these four factors, 3D chemocentric target prediction of an unknown compound requires compound–target associations, which replace compound-to-compound comparisons with compound-to-target comparisons. In this study, quantitative comparison of query compounds to target classes (one-to-group) was achieved via two types of 3D similarity distributions for the respective target class with parameter optimization for the fitting models: (1) maximum likelihood (ML) estimation of queries, and (2) the Gaussian mixture model (GMM) of target classes. While Jaccard–Tanimoto similarity of query-to-ligand pairs with 3D structures (sampled multi-conformers) can be transformed into query distribution using ML estimation, the ligand pair similarity within each target class can be transformed into a representative distribution of a target class through GMM, which is hyperparameterized via the expectation–maximization (EM) algorithm. To quantify the discriminativeness of a query ligand against target classes, the Kullback–Leibler (K–L) divergence of each query was calculated and compared between targets. 3D similarity-based K–L divergence together with the probability and the feasibility index, (Fm), showed discriminative power with regard to some query–class associations. The K–L divergence of 3D similarity distributions can be an additional method for (1) the rank of the 3D similarity score or (2) the p-value of one 3D similarity distribution to predict the target of unprecedented drug scaffolds.
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MÅNSSON, MARIANNE. "On Compound Poisson Approximation for Sequence Matching." Combinatorics, Probability and Computing 9, no. 6 (November 2000): 529–48. http://dx.doi.org/10.1017/s096354830000448x.

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Consider sequences {Xi}mi=1 and {Yj}nj=1 of independent random variables, taking values in a finite alphabet, and assume that the variables X1, X2, … and Y1, Y2, … follow the distributions μ and v, respectively. Two variables Xi and Yj are said to match if Xi = Yj. Let the number of matching subsequences of length k between the two sequences, when r, 0 [les ] r < k, mismatches are allowed, be denoted by W.In this paper we use Stein's method to bound the total variation distance between the distribution of W and a suitably chosen compound Poisson distribution. To derive rates of convergence, the case where E[W] stays bounded away from infinity, and the case where E[W] → ∞ as m, n → ∞, have to be treated separately. Under the assumption that ln n/ln(mn) → ρ ∈ (0, 1), we give conditions on the rate at which k → ∞, and on the distributions μ and v, for which the variation distance tends to zero.
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Gómez-Déniz, Emilio, and Luis Gómez. "The Rayleigh Birnbaum Saunders Distribution: A General Fading Model." Symmetry 12, no. 3 (March 3, 2020): 389. http://dx.doi.org/10.3390/sym12030389.

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A new compound non-symmetric distribution for modeling arbitrary fading-shadowing wireless channels is introduced and studied here. This distribution has some advantages in front of other well-known non-symmetric fading distributions such as the Rayleigh–lognormal distribution and the K distribution especially in the tails. We give closed-form expressions for the average BER of DPSK and MSK when the new distribution is used. Applications to compare how the new distribution works in comparisons with the Rayleigh–lognormal, K distributions and others recently proposed in the literature of fading channel are also provided.
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Jeon, Ji-Hyeon, Bitna Kang, Sowon Lee, Sojeong Jin, Min-Koo Choi, and Im-Sook Song. "Pharmacokinetics and Intestinal Metabolism of Compound K in Rats and Mice." Pharmaceutics 12, no. 2 (February 3, 2020): 129. http://dx.doi.org/10.3390/pharmaceutics12020129.

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We aimed to investigate the plasma concentration, tissue distribution, and elimination of compound K following the intravenous administration of compound K (2 mg/kg) in rats and mice. The plasma concentrations of compound K in mice were much higher (about five-fold) than those in rats. In both rats and mice, compound K was mainly distributed in the liver and underwent biliary excretion. There was 28.4% fecal recovery of compound K in mice and 13.8% in rats, whereas its renal recovery was less than 0.1% in both rats and mice. Relative quantification of compound K and its metabolite protopanaxadiol (PPD) in rat bile and intestinal feces indicated that the metabolism from compound K into PPD occurred in the intestine but not in the plasma. Therefore, PPD detected in the plasma samples could have been absorbed from the intestine after metabolism in control rats, while PPD could not be detected in the plasma samples from bile duct cannulated rats. In conclusion, mice and rats shared common features such as exclusive liver distribution, major excretion pathway via biliary route, and intestinal metabolism to PPD. However, there were significant differences between rats and mice in the plasma concentrations of compound K and the fecal recovery of compound K and PPD.
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Jamei, Saeed, Adi Maimun, Rasul Niazmand Bilandi, Nor Azwadi, Simone Mancini, Luigi Vitiello, and Maria De Carlini. "Wake behind a Compound Wing in Ground Effect." Journal of Marine Science and Engineering 8, no. 3 (March 1, 2020): 156. http://dx.doi.org/10.3390/jmse8030156.

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Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower surface for the compound wing. However, the suction effect on the upper surface of the rectangular wing was higher. Also, the velocity defect and the turbulence level in the wake area was greater behind the compound wing.
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Fardhyanti, Dewi Selvia, Achmad Chafidz, Bayu Triwibowo, Haniif Prasetiawan, Novia Noor Cahyani, and Sinta Andriyani. "Improving the Quality of Bio-Oil Produced from Rice Husk Pyrolysis by Extraction of its Phenolic Compounds." Jurnal Bahan Alam Terbarukan 8, no. 2 (December 17, 2020): 90–100. http://dx.doi.org/10.15294/jbat.v8i2.22530.

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Rice husk is an agricultural waste which contains 50% cellulose, 25%-30% lignin and 15%-20% silica. It can be used as raw material of bio-oil. Bio-oil is liquid which produced by pyrolysis process. Bio-oil can be produced from the rice husk at 773 and 873 K. The main component of Bio-oil from rice husk pyrolysis at 773 and 873 K is phenolic compounds about 47.98% and 62.65%, respectively. It causes corrosive, low heating value, high acidity, high viscosity and unstable that causing an engine damage. The presence of phenolic compound decreases the quality of bio-oil. Therefore, it needs a process such as liquid-liquid extraction to reduce the phenolic compound using 80% methanol and 80% chloroform as a solvent. The extract and raffinate phase were analyzed using UV-Vis spectrophotometer. The aim of this research determine the effect of temperature pyrolysis for the characterization of bio-oil, the stirring speed and the temperature of the extraction for the distribution coefficient and the yield of phenolic compound. The results showed that the characterization of bio-oil produced from rice husk pyrolysis at 773 and 873 K are densities 1,040 and 1,042 Kg/m3; viscosities 9.3488 and 9.5007 cSt; acid numbers 46.75 and 52.45 mg KOH/g; pH 2.5 and 3; flash points 426 and 423 K and heating values 3.229 and 3.339 MJ/kg, respectively. The highest distribution coefficient and yield were obtained at 323 K and a stirring speed of 250 rpm. The distribution coefficient of bio-oil produced by pyrolysis at 773 and 873 K is 1.504, and 1.528, respectively. The yields of bio-oil produced by pyrolysis at 773 and 873 K are 58.885%, and 48.429%, respectively.
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Watts, S. "Radar detection prediction in sea clutter using the compound K-distribution model." IEE Proceedings F Communications, Radar and Signal Processing 132, no. 7 (1985): 613. http://dx.doi.org/10.1049/ip-f-1.1985.0115.

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Geske, Mark X., Anant P. Godbole, Andrew A. Schaffner, Allison M. Skolnick, and Garrick L. Wallstrom. "Compound Poisson approximations for word patterns under Markovian hypotheses." Journal of Applied Probability 32, no. 4 (December 1995): 877–92. http://dx.doi.org/10.2307/3215201.

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Consider a stationary Markov chain with state space consisting of the ξ -letter alphabet set Λ= {a1, a2, ···, aξ }. We study the variables M=M(n, k) and N=N(n, k), defined, respectively, as the number of overlapping and non-overlapping occurrences of a fixed periodic k-letter word, and use the Stein–Chen method to obtain compound Poisson approximations for their distribution.
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Cai, Jun, and Qihe Tang. "On max-sum equivalence and convolution closure of heavy-tailed distributions and their applications." Journal of Applied Probability 41, no. 01 (March 2004): 117–30. http://dx.doi.org/10.1017/s002190020001408x.

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In this paper, we discuss max-sum equivalence and convolution closure of heavy-tailed distributions. We generalize the well-known max-sum equivalence and convolution closure in the class of regular variation to two larger classes of heavy-tailed distributions. As applications of these results, we study asymptotic behaviour of the tails of compound geometric convolutions, the ruin probability in the compound Poisson risk process perturbed by an α-stable Lévy motion, and the equilibrium waiting-time distribution of the M/G/k queue.
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Dissertations / Theses on the topic "Compound K-distribution"

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Ronden, Jacintha Elisabeth. "Absorption, tissue distribution and bioactivity of vitamin K and related compounds in the rat." Maastricht : Maastricht : Universiteit Maastricht ; University Library, Maastricht University [Host], 1998. http://arno.unimaas.nl/show.cgi?fid=5981.

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"Modeling and Parameter Estimation of Sea Clutter Intensity in Thermal Noise." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.53933.

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abstract: A critical problem for airborne, ship board, and land based radars operating in maritime or littoral environments is the detection, identification and tracking of targets against backscattering caused by the roughness of the sea surface. Statistical models, such as the compound K-distribution (CKD), were shown to accurately describe two separate structures of the sea clutter intensity fluctuations. The first structure is the texture that is associated with long sea waves and exhibits long temporal decorrelation period. The second structure is the speckle that accounts for reflections from multiple scatters and exhibits a short temporal decorrelation period from pulse to pulse. Existing methods for estimating the CKD model parameters do not include the thermal noise power, which is critical for real sea clutter processing. Estimation methods that include the noise power are either computationally intensive or require very large data records. This work proposes two new approaches for accurately estimating all three CKD model parameters, including noise power. The first method integrates, in an iterative fashion, the noise power estimation, using one-dimensional nonlinear curve fitting, with the estimation of the shape and scale parameters, using closed-form solutions in terms of the CKD intensity moments. The second method is similar to the first except it replaces integer-based intensity moments with fractional moments which have been shown to achieve more accurate estimates of the shape parameter. These new methods can be implemented in real time without requiring large data records. They can also achieve accurate estimation performance as demonstrated with simulated and real sea clutter observation datasets. The work also investigates the numerically computed Cram\'er-Rao lower bound (CRLB) of the variance of the shape parameter estimate using intensity observations in thermal noise with unknown power. Using the CRLB, the asymptotic estimation performance behavior of the new estimators is studied and compared to that of other estimators.
Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2019
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Book chapters on the topic "Compound K-distribution"

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Burzo, E. "Extraframework cation distribution in K-X and K-Y faujasites." In Magnetic Properties of Non-Metallic Inorganic Compounds Based on Transition Elements, 235–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49337-3_7.

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Burzo, E. "Crystal structure and cation distribution in Mmn+ – X(M = Na, K, Rb, Cs)faujasites." In Magnetic Properties of Non-Metallic Inorganic Compounds Based on Transition Elements, 318–20. Berlin, Heidelberg: Springer Berlin Heidelberg, 2017. http://dx.doi.org/10.1007/978-3-662-49337-3_10.

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Wierzchon, Slawomir T. "Ensemble Clustering Data Mining and Databases." In Encyclopedia of Information Science and Technology, Fourth Edition, 1962–73. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-2255-3.ch170.

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Standard clustering algorithms employ fixed assumptions about data structure. For instance, the k-means algorithm is applicable for spherical and linearly separable data clouds. When the data come from multidimensional normal distribution – so-called EM algorithm can be applied. But in practice the assumptions underlying given set of observations are too complex to fit into a single assumption. We can split these assumptions into manageable hypothesis justifying the use of particular clustering algorithms. Then we must aggregate partial results into a meaningful description of our data. The consensus clustering do this task. In this article we clarify the idea of consensus clustering, and we present conceptual frames for such a compound analysis. Next the basic approaches to implement consensus procedure are given. Finally, some new directions in this field are mentioned.
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Wierzchon, Slawomir T. "Ensemble Clustering Data Mining and Databases." In Advances in Computer and Electrical Engineering, 563–76. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7598-6.ch041.

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Standard clustering algorithms employ fixed assumptions about data structure. For instance, the k-means algorithm is applicable for spherical and linearly separable data clouds. When the data come from multidimensional normal distribution, so-called EM algorithm can be applied. But in practice, the assumptions underlying given set of observations are too complex to fit into a single assumption. We can split these assumptions into manageable hypothesis justifying the use of particular clustering algorithms. Then we must aggregate partial results into a meaningful description of our data. The consensus clustering does this task. In this chapter, the authors clarify the idea of consensus clustering, and they present conceptual frames for such a compound analysis. Next, the basic approaches to implement consensus procedure are given. Finally, some new directions in this field are mentioned.
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D.R. Mackinnon, Ian, Alanoud Almutairi, and Jose A. Alarco. "Insights from Systematic DFT Calculations on Superconductors." In Real Perspective of Fourier Transforms and Current Developments in Superconductivity. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96960.

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We present three systematic approaches to use of Density Functional Theory (DFT) for interpretation and prediction of superconductivity in new or existing materials. These approaches do not require estimates of free parameters but utilize standard input values that significantly influence computational resolution of reciprocal space Fermi surfaces and that reduce the meV-scale energy variability of calculated values. Systematic calculations on conventional superconductors show that to attain a level of resolution comparable to the energy gap, two key parameters, Δk and the cut-off energy, must be optimized for a specific compound. The optimal level of resolution is achieved with k-grids smaller than the minimum reciprocal space separation between key parallel Fermi surfaces. These approaches enable estimates of superconducting properties including the transition temperature (Tc) via (i) measurement of the equivalent thermal energy of a phonon anomaly (if present), (ii) the distribution of electrons and effect on Fermi energy (EF) when subjected to a deformation potential and (iii) use of parabolic, or higher order quartic, approximations for key electronic bands implicated in electron–phonon interactions. We demonstrate these approaches for the conventional superconductors MgB2, metal substituted MgB2 and boron-doped diamond.
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Calvert, Jack, Abdelwahid Mellouki, John Orlando, Michael Pilling, and Timothy Wallington. "Rate Coefficients and Mechanisms for the Atmospheric Oxidation of the Ketones." In Mechanisms of Atmospheric Oxidation of the Oxygenates. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780199767076.003.0008.

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Ketones are emitted directly to the atmosphere, and their sources were discussed in detail in chapter I. In the U.K. acetone and butanone comprise about 7% and 5%, respectively, of the total anthropogenic emissions of oxygenated compounds, and 1.6% and 1.1%, respectively, of the total anthropogenic emissions of nonmethane volatile organic compounds. Ketone emissions from solvents (both industrial and personal) are substantial; emissions from both gasoline- and diesel-fueled vehicles also contribute. Ketones are also formed extensively in the atmosphere in the oxidation of other compounds. Acetone, for example is formed in the OH-initiated oxidation of propane, iso-butane, iso-pentane, and neopentane and from a number of higher hydrocarbons. It is also formed in the oxidation of terpenes. The distribution, sources, and sinks of acetone in the atmosphere have been analyzed by Simpson et al. (1994). Methyl vinyl ketone is an important first generation product in the OH-initiated oxidation of isoprene. In this chapter, we discuss the rate coefficients and the mechanisms of oxidation of ketones. The classes covered include alkanones, hydroxyketones, diketones, unsaturated ketones, ketenes, cyclic ketones, ketones derived from biogenic compounds, and halogen-substituted ketones. Photolysis is a major atmospheric process for many ketones, and will be discussed in chapter IX. The major bimolecular reactions removing ketones from the atmosphere are with OH. Although less important than the OH reactions, reactions with Cl have been studied quite extensively. Other than for unsaturated ketones, reactions with NO3 and O3 are unimportant in tropospheric chemistry and have been studied little. The carbonyl group deactivates the α-position with respect to reaction with OH, but activates the β-position, and possibly more distant sites as well. The net result is that the overall rate coefficient of an alkanone generally exceeds that of the equivalent alkane. The temperature dependences of the rate coefficients can be quite complex, with acetone and possibly butanone showing a minimum in the rate coefficient at ∼250 K, while the higher alkanones show negative temperature dependences across the more limited temperature ranges that have been investigated. The most likely explanation of this behavior is the formation of a pre-reaction, hydrogen-bonded complex.
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"(22) NILSSON, C. (1982). Dust investigations in pig houses. Swedish Uni­ versity of Agricultural Sciences, Department of Farm Buildings, Di-vison of Farm Building Constructions, Lund. Rapport 25, pp 93. (23) HILLIGER, H.G. (1966). Gravimetrische Staubmessungen in Stallen. Zbl. Vet. Med. B, 13, 698-708. (24) PALOHEIMO, L.T1969). Weender Analyse. In: W. LEMKEIT, K. BREIREM and E. GRASSMANN (Hrsg.). Handbuch der Tierernahrung, Bd. 1, S.164-171, Verlag Parey, Berlin, Hamburg. (25) HELEN, M. (1984). Einige Ursachen fUr die Variationen der Staubkon-zentration im Mastschweinestal1. In: Symposium der Internationalen Gesellschaft fUr Tierhygiene, Hrsg.: Deutsche Veterinarmedizinische GeselIschaft, 28-30. (26) NAKAUE, H.S., J.K. KOELLIKER, D.R. BUHLER and G.H. ARSCOTT (1981). Distribution of inorganic elements in poultry house dust. Poultry Sci. 60, 1386-1391. (27) CERMAK, J.P. and P.A. ROSS (1978). Airborne dust concentrations as­ sociated with animal housing tasks. Farm Buildg. Progr. 5J_, 11-15. (28) BUNDY, D.S. and E.T. HAZEN (1975). Dust levels in swine confinement systems associated with different feeding methods. Trans. Amer. Soc. Agric. Eng. J8, 137-139. (29) SCHAEFER, J., J.M.H. BEMELMANS and M.C. Ten NOEVER DE BRAUW (1974). Onderzoek naar de voor de stank van varkensmesterijen verantwoordi-lijke componenten. Landbouwkund. Tijdschr., pt 86-9, 228-232. (30) HAMMOND, E.G., C. FEDLER and G. JUNK (1979). Identification of dust-borne odors in swine confinement facilities. Trans. ASAE 22, No. 5, 1186-1189 & 1192. (31) TRAVIS, T.A. and L.F. ELLIOTT (1977). Quantitation of indole and scatole in a housed swine unit. J. Environ. Qual. 6 (34) HARTUNG, J. (1985). Gas chromatographic investigations of swine house dust on odorous compounds. Environmental Technology Letters 6, 21-30. (35) SPOELSTRA, S.F. (1978). Microbial aspects of the formation of malo­ dorous compounds in anaerobically stored piggery wastes. Wageningen, Landbouwhogeschool, Diss., pp. 91. (36) SCHAEFER, J. (1977). Sampling, characterization and analysis of mal-odours. Agric. Environm. 3, 121-127. (37) HARTUNG, J. and E. R0KICK.T (1984). Zum Vorkommen phenol art iger Ver-bindungen im Staub von Schweine- und HUhnerstall. Zbl. Bakt. Hyg., I. Abt. Orig. B, J_79, 431-439. (38) LOGTENBERG, M.Th. and B. STORK (1976). Het ontwikkelen van meetme-thoden voor het bepalen van de stank van ventilatielucht van mest-varkensstallen.Rapport de Centraal Technisch Instituut TNO, Zeist/ Holland. Ref.no: 76-06 054, Dossier: 01-4-40130. (39) WILLSON, G.B. (1971). Control of odours from poultry houses. ASAE Symp. Livestock Waste Management, Columbus/Ohio, 19.-22.4.1971. (40) HAMMOND, E.G., C. FEDLER and R.J. SMITH (1981). Analysis of particle -borne swine house odours. Agric. and Environment 6, 395-399. (41) OWEN, J.E. (1982b). Dust - Filtration solutions an? their cost. Farm Building Progress 68, 19-23." In Odour Prevention and Control of Organic Sludge and Livestock Farming, 340. CRC Press, 1986. http://dx.doi.org/10.1201/9781482286311-134.

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Conference papers on the topic "Compound K-distribution"

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Denny, M. "Simulating sea clutter via the compound-k distribution." In IEE Colloquium on Radar System Modelling. IEE, 1998. http://dx.doi.org/10.1049/ic:19980775.

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Ritchie, M. A., K. Woodbridge, and A. G. Stove. "Analysis of sea clutter distribution variation with Doppler using the compound k-distribution." In 2010 IEEE Radar Conference. IEEE, 2010. http://dx.doi.org/10.1109/radar.2010.5494569.

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Northrop, Judith, and Antonia Papandreou-Suppappola. "Estimation of Compound K-distribution Modeling Parameters of Sea Clutter with Unknown Thermal Noise Power." In 2018 52nd Asilomar Conference on Signals, Systems, and Computers. IEEE, 2018. http://dx.doi.org/10.1109/acssc.2018.8645205.

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Lin, Y. L., M. A. Stephens, and T. I.-P. Shih. "Computation of Leading-Edge Film Cooling With Injection Through Rows of Compound-Angle Holes." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-298.

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Computations were performed to investigate the three-dimensional flow and heat transfer about a semi-cylindrical leading edge with a flat afterbody that is cooled by film-cooling jets, injected through three staggered rows of compound-angle holes with one row along the stagnation line and two rows along ±25°. Results are presented for the surface adiabatic effectiveness, temperature distribution, velocity vector field, turbulent kinetic energy, and surface pressure. These results show the interactions between the mainstream hot gas and the cooling jets, and how those interactions affect surface adiabatic effectiveness. The computed results were compared with experimental data generated under a blind test, and reasonably good agreements were obtained. This computational study is based on the ensemble-averaged conservation equations of mass, momentum (compressible Navier-Stokes), and energy closed by a low Reynolds number k-ω turbulence model. Solutions were generated by a cell-centered finite-volume method that uses second-order accurate flux-difference splitting of Roe on a multiblock structured grid system. In the computations, the flow is resolved not just in the region about the leading edge, but also inside the film-cooling holes and in the plenum where the cooling flow emerges.
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Li, Jia, Jing Ren, and Hongde Jiang. "Film Cooling Performance of the Embedded Holes in Trenches With Compound Angles." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22337.

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Film cooling performance for a row of cylindrical holes can be enhanced by embedding the row in a suitable transverse slot. The compound angle of the holes can even more affects the cooling performance at downstream of the injections. In this study the cooling performance of the embedded holes in transverse trenches with different compound angles are explored both by pressure sensitive paint (PSP) experiment technology and RANS algorithm. A film cooling test rig was built up in Tsinghua University, which contains an accelerating free stream section to model the surface of a turbine airfoil. The PSP technology is applied in the tests to obtain the film cooling effectiveness. The experiments are performed for a single mainstream Reynolds number based on free-stream velocity and film hole diameter of 4000. Considering three compound angles, 0°, 45° and 90°, and with or without transverse trenches. All six cases are tested at three different coolant-to-mainstream blowing ratios of 0.5, 1.0, and 1.5. Meanwhile, the test cases are numerically simulated based on RANS with k-ε turbulence model to show the detail of the flow patterns. Both the experimental and numerical results show that the adiabatic film effectiveness is relative insensitive to the blowing ratio in the case of holes with trenches. Moreover, it could be improved with a more uniform spanwise distribution. It is mainly due to the blockage of the ejected coolant at the downstream edge of the trench, which forces a portion of the cooling air to spread laterally within the trench prior to issuing onto the upper surface. Both 45° and 90° compound angles can further enhance the film cooling effectiveness over the axial ejection, this is mainly due to the lateral momentum component of the ejection. A lateral passage vortex is formed inside the trench which strengthens the lateral spreading of the jets. The 45° compound angle gives a higher film cooling effectiveness overall.
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Li, Weihong, Wei Shi, Xueying Li, Jing Ren, and Hongde Jiang. "Large Eddy Simulation of Axial and Compound Angle Holes With Varying Hole Length-to-Diameter Ratio." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63308.

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The effect of hole length to diameter ratio on flat plate film cooling effectiveness and flow structures of axial and compound angle hole is investigated by large eddy simulation (LES). Film cooling simulations are performed for three blowing ratios (M) ranging from 0.4 to 1.2, three hole length-to-diameter ratios (L/D) from 0.5 to 5 and two compound angle (β: 0°, 45°). The prediction accuracy is validated by the reported hydrodynamic data and present film effectiveness data measured by pressure sensitive paint (PSP). Results indicate that discrete hole with L = 0.5 show highest film cooling effectiveness regardless of compound angle. Round hole generally shows an increasing trend as L increases from 2 to 5, while compound angle hole shows a complex trend concerning with blowing ratios and length to diameter ratios. This is associated with the fact that length-to-diameter ratio influences the in-tube flow behavior, formation of Kelvin-Helmholtz (K-H) structures, and development of single asymmetric main vortex (SAMV). Scalar field transportation features are investigated to clarify how different vortex structures affect the temperature distribution and the film cooling effectiveness. It is also demonstrated that the counter rotating vortex pair (CRVP) which is observed in the time-averaged flow field of axial hole is originated in different vortex structures with varying blowing ratios and length to diameter ratios.
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Ingram, Peter T., and Savas Yavuzkurt. "Derivation of 2-D Empirical Correlations for Film-Cooling Effectiveness and Heat Transfer Augmentation From Spanwise Averaged Data and Correlations." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95149.

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In existing gas turbine heat transfer literature, there are several correlations developed for the spanwise-averaged film-cooling effectiveness and heat transfer augmentation for inline injection on flat plates. More accurate and detailed predictions of film-cooling performance, particularly 3-D solid temperatures are needed for design purposes. 2-D correlations where effectiveness and heat transfer augmentation are functions of streamwise and spanwise directions are necessary to satisfy this need. Previously developed 2-D correlations for single row of cylindrical holes with inline injection have been improved to include the effects of shaped holes such as hole breakthrough width (t/D) and area ratio (AR). The correlations are improved to better match spanwise effectiveness of a single row of shaped cooling holes using data and spanwise-averaged correlations. Modifications to the correlations to improve application to compound injection (β) have been implemented. The blowing ratio is modified to account for the compound angle effect. The spanwise location of maximum film-cooling effectiveness and heat transfer augmentation are obtained as functions of the streamwise coordinate. Iterative Conjugate Heat Transfer Reduced Order Film Model (ICHT-ROFM) was used to obtain 3-D conjugate temperature distribution in film cooled solids. The developed correlations predicted a relative cooling effect in the near hole region for shaped holes (24 K) and for compound angle injection (20K) compared to cylindrical holes. Spanwise variations in the solid temperature in the near hole region are between 40–50K for a temperature difference of 250K between the surface and the main stream and are quite significant, showing the need for 3-D simulations. Shaped and compound angle holes increase this temperature difference due to the increased cooling. The comparisons of solid temperatures for conjugate and non-conjugate heat transfer cases show about 13–18K or 8–10% of the local temperature difference of 180K. Therefore it can be concluded that the calculations of 3-D temperature distributions using conjugate heat transfer are very important for design purposes.
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8

Laroche, Emmanuel, David Donjat, and Philippe Reulet. "A Combined Experimental and Numerical Characterization of the Flowfield and Heat Transfer Around a Multiperforated Plate With Compound Angle Injection." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-16311.

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Abstract The aerodynamic and thermal behaviour of multiperforated zones in combustors is essential to the development of future combustion chambers. Detailed databases are therefore essential for the validation of RANS/LES solvers, but also regarding the derivation of heat transfer correlations used in 0D/1D in-house codes developed by engine manufacturers. In the framework of FP7 EU SOPRANO Program, the test-rig used in a previous study is modified to be compatible with anisothermal conditions. The plate studied is a 12:1 model with a 90° compound angle injection. A heating system is used to generate a moderate temperature gradient of about 20 K between the secondary hot flow and the main cold flow. The aerodynamic field is acquired by a PIV 2D-3C (Particle Image Velocimetry) system. The surface heat transfer coefficient is derived based on surface temperature distribution acquisitions. Several heating power levels are tested, which allows to evaluate the convective heat transfer coefficient and reference temperature through a linear regression. Measurements are conducted on both sides of the plate, which also gives access to those quantities on the injection/suction sides. From a numerical point of view, the configuration is studied using the unstructured ONERA in-house CEDRE solver. A systematic comparison is presented between the experimental and numerical database.
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9

Hii, Wilson W. S., and Donna J. Michalek. "Development of a Transient CFD Model of an SI Fuel Injector." In ASME 2002 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/ices2002-451.

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As the use of fuel injection in spark ignition engines has increased, continuous refinements in the design of fuel injectors are needed in order to obtain lower engine emissions and increased performance. In this endeavor, computational fluid dynamics (CFD) has been used as a means of gaining an understanding of the flow through the injector, and also as a valuable tool in the design process. Most CFD models constructed to study injector flow utilize the standard k-ε turbulence model and perform steady state calculations with the fuel injector needle held in a fixed position. The objectives of this research were to determine the appropriate turbulence model for this flow situation and the accuracy of using a steady state analysis to simulate the transient flow in an operational fuel injector. An evaluation of three turbulence models was performed. The standard k-ε, along with the Renormalisation Group (RNG) and the Chen modifications of the k-ε scheme were used to obtain steady state flow results for a fuel injector in the fully open position. Star-CD was used to perform the simulations of two fuel injectors containing Ford compound nozzles, which are specifically designed to generate turbulent flow just upstream of the injector exit. This comparison resulted in the determination of an appropriate turbulence model, which was then used in a transient CFD simulation of the injector. In addition to the transient simulation, which modeled the opening and closing processes, four steady state simulations were performed at different needle lift positions. The results obtained from these steady state simulations were compared to those from the transient simulation at the same needle lift positions. In all cases, the flow properties used for the comparisons were the fluid velocity, the turbulent kinetic energy, and the turbulent dissipation in the nozzle exit plane. This location was chosen because of its influence on the spray dispersion and droplet size distribution produced by the injector. From the turbulence model study it was determined that the Renormalisation group and Chen’s modifications schemes were preferred over the standard k-ε scheme for predicting the turbulent flow properties. Comparisons between the transient and steady state simulation results clearly illustrated that the rapid movement of the pintle needle during the opening and closing processes greatly influences the flow at the injector exit. From these observations, it was determined that a fuel injector can operate entirely within the transient mode. Therefore, it was concluded that a transient simulation is the preferred method to use for injector analysis.
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10

Maeda, Noriyoshi, and Tetsuo Shoji. "Failure Probability Analysis Based on FRI Model for SCC Growth Introducing Stress Intensity Factor Distribution as Function of Crack Depth." In ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57926.

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Failure probability of welds by stress corrosion cracking (SCC) in austenitic stainless steel piping is analyzed by probabilistic fracture mechanics (PFM) approach based on an electro-chemical crack growth model named FRI model[1] through which a basic equation is derived. Introducing the relation among dK/dt, da/dt and dK/da (K: stress intensity factor, a: crack depth and t: time) into the basic equation, modified basic equation is derived which can give da/dt in explicit form in contrast to the fact that the basic equation is transcendental and can be solved only numerically by iterative method. From numerical evaluation of K distribution at a crack tip under bending stress, it is realized that there exists a relation between a and K and it can be expressed approximately by quadratic function, i.e. K=Km{1−(a−am)2/am2}. By examining K as function of a, am is proved to be a linear function of membrane stress to bending stress ratio. These findings are incorporated into the modified basic equation which is shown to be able to calculate da/dt without instability and needs no iteration. Stratified Monte-Carlo method is introduced which defines two dimensional sampling space composed of a/c (c is crack length at surface) ranging from 0 to 1 and K from 0 to Kw which has to be defined referring to KSCC. Log-normal distributions are anticipated for a/c and K probability distributions. The median of K is decided referring to median of a in Bru¨ckner model. Parameter surveys for cumulative failure probability (CFP) performed with the basic equation and the modified basic equation give very close results. In this study, the residual stress distribution generated by residual stress at welding is anticipated to be tensile on inner surface and compressive on outer surface like bending stress distribution. Therefore the simulation is performed under bending dominative condition. The modified basic equation is proved to need about 1/2 calculation time of needed by the original basic equation in the CFP simulation.
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