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1
Sun, Menghan, e Hui Qi. "Scattering of Antiplane SH Waves by Complex Landforms". Shock and Vibration 2021 (5 agosto 2021): 1–21. http://dx.doi.org/10.1155/2021/9997230.
Testo completoAbstract (sommario):
The multiple scattering of SH waves by isosceles triangular hill, semicircle depression, and isosceles trapezoidal hill in the solid half-space is studied. The complex model is divided into multiple subdomains by using the region matching method, then the wave functions in each subdomain are constructed by using the fractional-order Bessel function, and finally, the infinite algebraic equations for solving the unknown coefficients in the wave function are established by using the multipolar coordinate technique and the complex function method according to the boundary conditions. Fourier series is used to solve the unknown undetermined coefficients. The results show that due to the multiple reflections of the incident wave between complex landforms, surface displacement amplitude is affected by the incident angle, incident frequency, and the distance between the isosceles triangular hill, semicircle depression, and isosceles trapezoidal hill. It is found that when the incident frequency increases, there is a certain amplification effect between the hills and the depression. When the wave is incident horizontally, there is a certain “barrier” effect between hills and depression, and when the distance between the hills and depression reaches a certain level, the “barrier” effect will reach a stable value.
2
Liu, Hu e Wang. "Large Eddy Simulations of the Flow Fields over Simplified Hills with Different Roughness Conditions, Slopes, and Hill Shapes: A Systematical Study". Energies 12, n. 18 (4 settembre 2019): 3413. http://dx.doi.org/10.3390/en12183413.
Testo completoAbstract (sommario):
Turbulent flow fields over topographies are important in the area of wind energy. The roughness, slope, and shape of a hill are important parameters affecting the flow fields over topographies. However, these effects are always examined separately. The systematic investigations of these effects are limited, the coupling between these effects is still unrevealed, and the turbulence structures as a function of these effects are still unclear. Therefore, in the present study, the flow fields over twelve simplified isolated hills with different roughness conditions, slopes, and hill shapes are examined using large eddy simulations. The mean velocities, velocity fluctuations, fractional speed-up ratios, and visualizations of the turbulent flow fields are presented. It is found that as the hill slope increases, the roughness effects become weaker, and the roughness effects will further weaken as the hill changes from 3D to 2D. In addition, the fractional speed-up ratio at the summit of rough hills can even reach to three times as large as that over the corresponding smooth hills. Furthermore, the underestimation of the ratios of spanwise fluctuation to the streamwise fluctuation by International Electrotechnical Commission (IEC) 61400-1 is quite obvious when the hill shape is 3D. Finally, coherent turbulence structures can be identified for smooth hills, and as the hill slope increases, the coherent turbulence structures will experience clear evolutions. After introducing the ground roughness, the coherent turbulence structures break into small eddies.
3
Yang, Rui, Ting Ting Wang e Wei Wei Xia. "Research of Influence of Obstacles on Three-Dimensional Hill Wind Field". Applied Mechanics and Materials 448-453 (ottobre 2013): 1712–15. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.1712.
Testo completoAbstract (sommario):
At different wind speeds, in order to study the impact of obstacle size and distance to the bottom of the hill on wind farm, using Pro / E generates the model of hills and upstream obstacle, sinusoidal model was selected to the hill contour, then Fluent was adopted to analyze the flow field, turbulence model select the SSK k-ω, inlet boundary condition was exponential function. Wind speed distribution and wind pressure distribution of hill surface at each case were depicted by the simulation results; the obstacle of conducive for wind farms was obtained by comparing flow field distribution of each case.
4
Gonze, Didier, e Wassim Abou-Jaoudé. "The Goodwin Model: Behind the Hill Function". PLoS ONE 8, n. 8 (1 agosto 2013): e69573. http://dx.doi.org/10.1371/journal.pone.0069573.
Testo completo
5
Gulayeva, N. M., e S. A. Yaremko. "EXPERIMENTAL ANALYSIS OF MULTINATIONAL GENETIC ALGORITHM AND ITS MODIFICATIONS". Radio Electronics, Computer Science, Control, n. 2 (3 luglio 2021): 71–83. http://dx.doi.org/10.15588/1607-3274-2021-2-8.
Testo completoAbstract (sommario):
Context. Niching genetic algorithms are one of the most popular approaches to solve multimodal optimization problems. When classifying niching genetic algorithms it is possible to select algorithms explicitly analyzing topography of fitness function landscape; multinational genetic algorithm is one of the earliest examples of these algorithms. Objective. Development and analysis of the multinational genetic algorithm and its modifications to find all maxima of a multimodal function. Method. Experimental analysis of algorithms is carried out. Numerous runs of algorithms on well-known test problems are conducted and performance criteria are computed, namely, the percentage of convergence, real (global, local) and fake peak ratios; note that peak rations are computed only in case of algorithm convergence. Results. Software implementation of a multinational genetic algorithm has been developed and experimental tuning of its parameters has been carried out. Two modifications of hill-valley function used for determining the relative position of individuals have been proposed. Experimental analysis of the multinational genetic algorithm with classic hill-valley function and with its modifications has been carried out. Conclusions. The scientific novelty of the study is that hill-valley function modifications producing less number of wrong identifications of basins of attraction in comparison with classic hill-valley function are proposed. Using these modifications yields to performance improvements of the multinational genetic algorithm for a number of test functions; for other test functions improvement of the quality criteria is accompanied by the decrease of the convergence percentage. In general, the convergence percentage and the quality criterion values demonstrated by the algorithm studied are insufficient for practical use in comparison with other known algorithms. At the same time using modified hill-valley functions as a post-processing step for other niching algorithms seems to be a promising improvement of performance of these algorithms.
6
LIKHOSHVAI, VITALI, e ALEXANDER RATUSHNY. "GENERALIZED HILL FUNCTION METHOD FOR MODELING MOLECULAR PROCESSES". Journal of Bioinformatics and Computational Biology 05, n. 02b (aprile 2007): 521–31. http://dx.doi.org/10.1142/s0219720007002837.
Testo completoAbstract (sommario):
Development of an in silico cell is an urgent task of systems biology. The core of this cell should consist of mathematical models of intracellular events, including enzymatic reactions and control of gene expression. For example, the minimal model of the E. coli cell should include description of about one thousand enzymatic reactions and regulation of expression of approximately the same number of genes. In many cases detailed mechanisms of molecular processes are not known. In this study, we propose a generalized Hill function method for modeling molecular events. The proposed approach is a method of kinetic data approximation in view of additional data on structure functional features of molecular genetic systems and actually does not demand knowledge of their detailed mechanisms. Generalized Hill function models of an enzymatic reaction catalyzed by the tryptophan-sensitive 3-deoxy-d-arabino-heptulosonate-7-phosphate synthase and the cydAB operon expression regulation are presented.
7
Peng, Xing Qian, e Ling Lin Shi. "Analysis of Wind Load Effect on the Roof of Low-Rise Building in the Mountain Terrain". Advanced Materials Research 382 (novembre 2011): 176–82. http://dx.doi.org/10.4028/www.scientific.net/amr.382.176.
Testo completoAbstract (sommario):
The wind conditions of the low-rise building in the mountain terrain are different because they have the characteristics of different landforms. When the typhoon comes, the possibility of structural damage is increasing by the negative effects of wind in the special topography. By establishing a sine function of outline of the hill, this paper makes a CFD(Computational Fluid Dynamics) numerical simulation about the low-rise building around the hills with four different height. Using ANSYS-CFX software as calculating platform, it put forward the roof wind load effect of the Low-rise building by study the characteristics of the hill, the law of wind pressure distribution and the influence to roof wind load by wind direction and the high of the hill, the conclusions which can provide a reference for wind-resistant design have practical significance.
8
Vaughan, Diane E., Sheldon H. Jacobson e Derek E. Armstrong. "A New Neighborhood Function for Discrete Manufacturing Process Design Optimization Using Generalized Hill Climbing Algorithms". Journal of Mechanical Design 122, n. 2 (1 marzo 2000): 164–71. http://dx.doi.org/10.1115/1.533566.
Testo completoAbstract (sommario):
Discrete manufacturing process design optimization can be difficult, due to the large number of manufacturing process design sequences and associated input parameter setting combinations that exist. Generalized hill climbing algorithms have been introduced to address such manufacturing design problems. Initial results with generalized hill climbing algorithms required the manufacturing process design sequence to be fixed, with the generalized hill climbing algorithm used to identify optimal input parameter settings. This paper introduces a new neighborhood function that allows generalized hill climbing algorithms to be used to also identify the optimal discrete manufacturing process design sequence among a set of valid design sequences. The neighborhood function uses a switch function for all the input parameters, hence allows the generalized hill climbing algorithm to simultaneously optimize over both the design sequences and the inputs parameters. Computational results are reported with an integrated blade rotor discrete manufacturing process design problem under study at the Materials Process Design Branch of the Air Force Research Laboratory, Wright Patterson Air Force Base (Dayton, Ohio, USA). [S1050-0472(00)01002-3]
9
Pérez-Correa, José Ricardo, Gastón Lefranc e Mario Fernández-Fernández. "A New Application of the Hill Repressor Function: Automatic Control of a Conic Tank Level and Local Stability Analysis". Mathematical Problems in Engineering 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/271216.
Testo completoAbstract (sommario):
The Hill function is commonly used as a building block to model different dynamic patterns found in the response of genetic regulatory circuits within microorganisms and cells. These circuits are characterized by fast response and robustness against unmeasured disturbances. Therefore, microorganisms and cells can survive even if they are subjected to strong changes in their environment. However, as far as we know, the Hill function has not been used before to design process control systems. In this work, the repressor Hill function is applied to control the level of a conic tank. To eliminate the offset, we added integrative action. A local analysis was applied to define stability limits for the control parameters. A cost function that includes the error and the control effort was used to compare the performance of the Hill control against a standard PI and a PID-Dahlin controller.
10
Resnick, Sidney, e Cătălin Stărică. "Smoothing the Hill Estimator". Advances in Applied Probability 29, n. 01 (marzo 1997): 271–93. http://dx.doi.org/10.1017/s0001867800027889.
Testo completoAbstract (sommario):
For sequences of i.i.d. random variables whose common tail 1 – F is regularly varying at infinity wtih an unknown index –α < 0, it is well known that the Hill estimator is consistent for α–1 and usually asymptotically normally distributed. However, because the Hill estimator is a function of k = k(n), the number of upper order statistics used and which is only subject to the conditions k →∞, k/n → 0, its use in practice is problematic since there are few reliable guidelines about how to choose k. The purpose of this paper is to make the use of the Hill estimator more reliable through an averaging technique which reduces the asymptotic variance. As a direct result the range in which the smoothed estimator varies as a function of k decreases and the successful use of the esimator is made less dependent on the choice of k. A tail empirical process approach is used to prove the weak convergence of a process closely related to the Hill estimator. The smoothed version of the Hill estimator is a functional of the tail empirical process.
11
Resnick, Sidney, e Cătălin Stărică. "Smoothing the Hill Estimator". Advances in Applied Probability 29, n. 1 (marzo 1997): 271–93. http://dx.doi.org/10.2307/1427870.
Testo completoAbstract (sommario):
For sequences of i.i.d. random variables whose common tail 1 – F is regularly varying at infinity wtih an unknown index –α < 0, it is well known that the Hill estimator is consistent for α–1 and usually asymptotically normally distributed. However, because the Hill estimator is a function of k = k(n), the number of upper order statistics used and which is only subject to the conditions k →∞, k/n → 0, its use in practice is problematic since there are few reliable guidelines about how to choose k. The purpose of this paper is to make the use of the Hill estimator more reliable through an averaging technique which reduces the asymptotic variance. As a direct result the range in which the smoothed estimator varies as a function of k decreases and the successful use of the esimator is made less dependent on the choice of k. A tail empirical process approach is used to prove the weak convergence of a process closely related to the Hill estimator. The smoothed version of the Hill estimator is a functional of the tail empirical process.
12
Baxter, M. Aaron, Thomas F. Fahlen, Rebecca L. Wilson e Bradley D. Jones. "HilE Interacts with HilD and Negatively Regulates hilA Transcription and Expression of the Salmonella enterica Serovar Typhimurium Invasive Phenotype". Infection and Immunity 71, n. 3 (marzo 2003): 1295–305. http://dx.doi.org/10.1128/iai.71.3.1295-1305.2003.
Testo completoAbstract (sommario):
ABSTRACT The ability of Salmonella enterica serovar Typhimurium to traverse the intestinal mucosa of a host is an important step in its ability to initiate gastrointestinal disease. The majority of the genes required for this invasive characteristic are encoded on Salmonella pathogenicity island 1 (SPI1), and their expression is controlled by the transcriptional activator HilA, a member of the OmpR/ToxR family of proteins. A variety of genes (hilC, hilD, fis, sirA/barA, csrAB, phoB, fadD, envZ/ompR, fliZ, hilE, ams, lon, pag, and hha) have been identified that exert positive or negative effects on hilA expression, although the mechanisms by which these gene products function remain relatively unclear. Recent work indicates that the small DNA-binding protein, Hha, has a significant role in repressing hilA transcription and the invasive phenotype, particularly in response to osmolarity signals. We have characterized the Salmonella-specific gene, hilE, and found that it plays an important regulatory role in hilA transcription and invasion gene expression. Mutation of hilE causes derepression of hilA transcription, and overexpression of hilE superrepresses hilA expression and the invasive phenotype. Bacterial two-hybrid experiments indicate that the HilE protein interacts with HilD, suggesting a possible mechanism for HilE negative regulation of hilA gene expression and the Salmonella invasive phenotype. Finally, we have found that the hilE gene resides on a region of the serovar Typhimurium chromosome that has many characteristics of a pathogenicity island.
13
Neale, K. W., e E. Chater. "General Solutions for the Inelastic Behavior of Pressurized Membranes". Journal of Applied Mechanics 54, n. 2 (1 giugno 1987): 269–74. http://dx.doi.org/10.1115/1.3173006.
Testo completoAbstract (sommario):
The small-deflection behavior of inelastic membranes supported along arbitrary contours and subjected to lateral pressure is considered. Hill and Stora˚kers’ (1980) solution for isotropic power-law hardening membranes is extended to a wide class of anisotropic material response. Applications to circular membranes are given for anisotropic materials characterized by Budiansky’s (1984) general transversely isotropic yield function. Specific results corresponding to the yield functions proposed by Hill (1979) and Bassani (1977) are also presented.
14
Ko, Sanghoon, e Sundaram Gunasekaran. "Analysis of cheese melt profile using inverse-Hill function". Journal of Food Engineering 87, n. 2 (luglio 2008): 266–73. http://dx.doi.org/10.1016/j.jfoodeng.2007.12.002.
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Qi, Hui, Jing Guo e Jie Yang. "The Ground Motion of Isosceles Triangular Hill in Right-Angle Plane Impacted by SH-Wave". Applied Mechanics and Materials 121-126 (ottobre 2011): 2363–66. http://dx.doi.org/10.4028/www.scientific.net/amm.121-126.2363.
Testo completoAbstract (sommario):
The analytical solution to the problem of the scattering of SH-wave by isosceles triangular hill in right-angle plane is given by using the methods of complex function and multiple coordinate. Firstly, the solution region is divided into two domains, where domain I involves isosceles triangular hill and a semi-circular bottom, domain II involves a semi-circular hollow in right-angle plane. And a standing wave function is constructed which satisfies the zero-stress conditions at the triangular wedges. In domain II, the scattering wave functions which satisfy the stress free boundary conditions at the free surfaces for the right-angle plane are constructed. Secondly, based on the conditions of the displacement continuity and stress continuity at the “common border” in the domains, a series of infinite algebraic equations are given and solved by truncation. Finally, some examples for amplitude of displacement on the surface are given. Numerical results show that amplitude of displacement on the surface is influenced by isosceles triangular hill.
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Ziraldo, Riccardo, e Lan Ma. "Computing intrinsic noise of the genetic regulation modeled by Hill functions". Journal of Computational Systems Biology 3, n. 1 (dicembre 2018): 1–15. http://dx.doi.org/10.15744/2455-7625.3.101.
Testo completoAbstract (sommario):
Intrinsic noise embedded in stochastic gene regulation due to low copy number of species has been studied using the approach of theoretical modeling and computational simulation, including the standard methods of stochastic simulation algorithm (SSA) and linear noise approximation (LNA). At average cell level, Hill functions are widely used as a compact format to represent gene regulation involving multi-transcription-factor binding and cooperativity. Heuristic SSA and LNA methods (hSSA and hLNA) have been applied to study stochastic models employing Hill functions. It is however unclear which modeling and simulation method is suitable to characterize intrinsic noise of Hill-type gene regulation with sufficient accuracy and computational efficiency. In this work, we perform noise analysis of two gene regulatory models represented by second-order activating and inhibitory Hill functions, seeking to evaluate the performance of five existing noise modeling methods. Specifically, SSA and LNA are applied to the full models that are expanded from the Hill functions containing only elementary reactions, while hSSA and hLNA are applied to reduced models where the Hill function is heuristically used. In addition, we characterize intrinsic noise using the slow-scale LNA (ssLNA) method that is recently proposed to deal with models with both fast and slow time scales. Using SSA as ground truth, we find that hSSA and hLNA underestimate the level of intrinsic noise in the Hill-type models, despite of high computational efficiency. The ssLNA approach calculates noise with comparable accuracy as SSA and LNA, while requesting much less computational resources. In addition, the chemical Langevin equation (CLE) under the same slow-scale framework simulates single-cell stochastic trajectories as accurately as SSA yet with significantly lower computational demands. This study shows that ssLNA complemented by slow-scale CLE offers a computational platform that out-performs the other four methods in characterizing intrinsic stochasticity of the Hill-type genetic models.
17
Lichtenberger, Achim, Torben Schreiber e Mkrtich H. Zardaryan. "First Results and Perspectives of a New Archaeological Project in the Armenian Capital Artaxata: From Artashes-Artaxias I to Roman Imperialism". Electrum 28 (2021): 245–76. http://dx.doi.org/10.4467/20800909el.21.016.13374.
Testo completoAbstract (sommario):
The paper deals with the first results of the Armenian-German Artaxata Project which was initiated in 2018. The city of Artaxata was founded in the 2nd century BC as the capital of the Artaxiad kingdom. The city stretches over the 13 hills of the Khor Virap heights and the adjacent plain in the Ararat valley. The new project focusses on Hill XIII and the Lower city to the south and the north of it. This area was investigated by magnetic prospections in 2018 and on the basis of its results, in total eleven 5 × 5 m trenches were excavated in 2019. On the eastern part of Hill XIII several structures of possibly domestic function were uncovered. They were laid out according to a regular plan and in total three phases could be determined. According to 14C data, the first phase already dates to the 2nd century BC while the subsequent two phases continue into the 1st/2nd century AD. In the 2019 campaign, the overall layout and exact function of the structures could not be determined and more excavations will be undertaken in the forthcoming years. North of Hill XIII the foundations of piers of an unfinished Roman aqueduct on arches were excavated. This aqueduct is attributed to the period 114–117 AD when Rome in vain tried to establish the Roman province of Armenia with Artaxata being the capital.
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Lo, Gane Samb. "Asymptotic behavior of Hill's estimate and applications". Journal of Applied Probability 23, n. 4 (dicembre 1986): 922–36. http://dx.doi.org/10.2307/3214466.
Testo completoAbstract (sommario):
The problem of estimating the exponent of a stable law is receiving an increasing amount of attention because Pareto's law (or Zipf's law) describes many biological phenomena very well (see e.g. Hill (1974)). This problem was first solved by Hill (1975), who proposed an estimate, and the convergence of that estimate to some positive and finite number was shown to be a characteristic of distribution functions belonging to the Fréchet domain of attraction (Mason (1982)). As a contribution to a complete theory of inference for the upper tail of a general distribution function, we give the asymptotic behavior (weak and strong) of Hill's estimate when the associated distribution function belongs to the Gumbel domain of attraction. Examples, applications and simulations are given.
19
Lo, Gane Samb. "Asymptotic behavior of Hill's estimate and applications". Journal of Applied Probability 23, n. 04 (dicembre 1986): 922–36. http://dx.doi.org/10.1017/s0021900200116109.
Testo completoAbstract (sommario):
The problem of estimating the exponent of a stable law is receiving an increasing amount of attention because Pareto's law (or Zipf's law) describes many biological phenomena very well (see e.g. Hill (1974)). This problem was first solved by Hill (1975), who proposed an estimate, and the convergence of that estimate to some positive and finite number was shown to be a characteristic of distribution functions belonging to the Fréchet domain of attraction (Mason (1982)). As a contribution to a complete theory of inference for the upper tail of a general distribution function, we give the asymptotic behavior (weak and strong) of Hill's estimate when the associated distribution function belongs to the Gumbel domain of attraction. Examples, applications and simulations are given.
20
Lo, Gane Samb. "Asymptotic behavior of Hill's estimate and applications". Journal of Applied Probability 23, n. 04 (dicembre 1986): 922–36. http://dx.doi.org/10.1017/s0021900200118716.
Testo completoAbstract (sommario):
The problem of estimating the exponent of a stable law is receiving an increasing amount of attention because Pareto's law (or Zipf's law) describes many biological phenomena very well (see e.g. Hill (1974)). This problem was first solved by Hill (1975), who proposed an estimate, and the convergence of that estimate to some positive and finite number was shown to be a characteristic of distribution functions belonging to the Fréchet domain of attraction (Mason (1982)). As a contribution to a complete theory of inference for the upper tail of a general distribution function, we give the asymptotic behavior (weak and strong) of Hill's estimate when the associated distribution function belongs to the Gumbel domain of attraction. Examples, applications and simulations are given.
21
Meehan, John F. "The Morgan Hill Earthquake of April 24, 1984—Effects on Hospitals and Public School Buildings". Earthquake Spectra 1, n. 3 (maggio 1985): 575–77. http://dx.doi.org/10.1193/1.1585278.
Testo completoAbstract (sommario):
Two hospitals constructed under the provisions of the Hospital Act and six public school buildings constructed under the provisions of the Field Act were investigated following the Morgan Hill earthquake and all were observed to have performed quite well during the Morgan Hill earthquake. Maintaining function in hospitals in an important aspect of the Hospital Act; neither of the two hospitals inspected suffered any loss of function.
22
Shi, Wen Pu. "Scattering of SH-Waves to Semi-Cylindrical Canyon and Rectangular Elastic Hill on the Ground". Advanced Materials Research 610-613 (dicembre 2012): 2544–51. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.2544.
Testo completoAbstract (sommario):
Wave function expansion method and Green function method were employed to study thescattering problem of SH-waves to the semi-cylindrical canyon and rectangular hill on the gr ound. First, the displacements in the half space and rectangular hill were given which can santisfy the stress-free conditions on the free boundaries. Then, the first kind of Fredholm integration equation of the unknown distribution stress was obtained by using the displacement conditions on the common boundary between the half-space and the rectangular hill, and Gauss-Legendre integration formula was used to solve the equation. The given example results show the feasibility and practicability of the method here.
23
Shenk, D., D. Schenk e M. A. Shubin. "Asymptotic expansion of the spectral function of the Hill operator". Functional Analysis and Its Applications 20, n. 1 (1986): 78–79. http://dx.doi.org/10.1007/bf01077328.
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Henrickson, Sarah E. "Is your immune system over the hill?" Science Immunology 4, n. 35 (3 maggio 2019): eaax8198. http://dx.doi.org/10.1126/sciimmunol.aax8198.
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Elaraby, Ahmed, e Ismail Elansary. "A Framework for Multi-Threshold Image Segmentation of Low Contrast Medical Images". Traitement du Signal 38, n. 2 (30 aprile 2021): 309–14. http://dx.doi.org/10.18280/ts.380207.
Testo completoAbstract (sommario):
Accurate medical images segmentation plays a vital role in contouring during diagnosis and treatment planning. To improve the segmentation accuracy in low contrast images, we propose a method by combining Hill entropy and fuzzy c-partition. Here, using membership function, an image is first transformed into fuzzy domain. Subsequently, the fuzzy Hill entropies are defined for foreground (object) and background. Next, the total fuzzy Hill entropy is maximized to compute the accurate threshold; this process is employed to calculate a proper parameter combination of membership function. This Hill entropy is then optimized to acquire an image threshold by Differential Evolution “DE” optimization algorithm. The key benefit of the presented approach is that it considers the information of background and object as well as interactions between them in threshold selection mechanism. The results and performance evaluations show the better accuracy of our technique over other existing approaches.
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Meyer, Karin, e Mark Kirkpatrick. "Up hill, down dale: quantitative genetics of curvaceous traits". Philosophical Transactions of the Royal Society B: Biological Sciences 360, n. 1459 (7 luglio 2005): 1443–55. http://dx.doi.org/10.1098/rstb.2005.1681.
Testo completoAbstract (sommario):
‘Repeated’ measurements for a trait and individual, taken along some continuous scale such as time, can be thought of as representing points on a curve, where both means and covariances along the trajectory can change, gradually and continually. Such traits are commonly referred to as ‘function-valued’ (FV) traits. This review shows that standard quantitative genetic concepts extend readily to FV traits, with individual statistics, such as estimated breeding values and selection response, replaced by corresponding curves, modelled by respective functions. Covariance functions are introduced as the FV equivalent to matrices of covariances. Considering the class of functions represented by a regression on the continuous covariable, FV traits can be analysed within the linear mixed model framework commonly employed in quantitative genetics, giving rise to the so-called random regression model. Estimation of covariance functions, either indirectly from estimated covariances or directly from the data using restricted maximum likelihood or Bayesian analysis, is considered. It is shown that direct estimation of the leading principal components of covariance functions is feasible and advantageous. Extensions to multi-dimensional analyses are discussed.
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Loha, J., e S. Das. "Function and Application of GIS in Precision Agriculture at Darjeeling Hill". International Journal of Computer Sciences and Engineering 6, n. 11 (30 novembre 2018): 749–52. http://dx.doi.org/10.26438/ijcse/v6i11.749752.
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Wood, Brandon M., e Steven J. Albrechtsen. "Power Development in Hill Climbing as a Function of Bicycle Weight". Medicine & Science in Sports & Exercise 40, Supplement (maggio 2008): S42. http://dx.doi.org/10.1249/01.mss.0000321631.79521.d0.
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Ehsan Elahi, Faizan, e Ammar Hasan. "A method for estimating Hill function-based dynamic models of gene regulatory networks". Royal Society Open Science 5, n. 2 (febbraio 2018): 171226. http://dx.doi.org/10.1098/rsos.171226.
Testo completoAbstract (sommario):
Gene regulatory networks (GRNs) are quite large and complex. To better understand and analyse GRNs, mathematical models are being employed. Different types of models, such as logical, continuous and stochastic models, can be used to describe GRNs. In this paper, we present a new approach to identify continuous models, because they are more suitable for large number of genes and quantitative analysis. One of the most promising techniques for identifying continuous models of GRNs is based on Hill functions and the generalized profiling method (GPM). The advantage of this approach is low computational cost and insensitivity to initial conditions. In the GPM, a constrained nonlinear optimization problem has to be solved that is usually underdetermined. In this paper, we propose a new optimization approach in which we reformulate the optimization problem such that constraints are embedded implicitly in the cost function. Moreover, we propose to split the unknown parameter in two sets based on the structure of Hill functions. These two sets are estimated separately to resolve the issue of the underdetermined problem. As a case study, we apply the proposed technique on the SOS response in Escherichia coli and compare the results with the existing literature.
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Scheeres, D. J. "Hill Stability of Configurations in the Full N-Body Problem". Proceedings of the International Astronomical Union 10, S318 (agosto 2015): 128–34. http://dx.doi.org/10.1017/s174392131500719x.
Testo completoAbstract (sommario):
AbstractRigorous results on Hill Stability for the classical N-body problem are in general unknown for N ≥ 3, due to the complex interactions that may occur between bodies and the many different outcomes which may occur. However, the addition of finite density for the bodies along with a rigidity assumption on their mass distribution allows for Hill stability to be easily established. In this note we generalize results on Hill stability developed for the Full 3-body problem and show that it can be applied to the Full N-body problem. Further, we find that Hill Stability concepts can be applied to identify types of configurations which can escape and types which cannot as a function of the system energy.
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Dharampal, Navjit, e Ralph W. Aye. "Hill Repair—Why It Is Still Relevant and Should Be Taught". Foregut: The Journal of the American Foregut Society 1, n. 2 (giugno 2021): 185–89. http://dx.doi.org/10.1177/26345161211025718.
Testo completoAbstract (sommario):
The Hill repair for gastroesophageal reflux disease, though effective, durable, and in some regards a superior repair, has unfortunately seen less widespread adoption in the laparoscopic era relative to Nissen and Toupet fundoplications. Some purported objections to the Hill repair include conceptual and technical barriers, need for intraoperative manometry, and lack of clear-cut advantages. However, it has proven to be remarkably durable at 20 years and beyond relative to other repairs, with a low side-effect profile; there are also unique applications of the Hill repair and Hill sutures which broaden one’s armamentarium for managing the spectrum of patients with reflux disease. Lastly, understanding its anatomic components strengthens the surgeon’s knowledge of the anatomy and function of the gastroesophageal junction and antireflux repairs.
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Petit, Antoine C., Jacques Laskar e Gwenaël Boué. "Hill stability in the AMD framework". Astronomy & Astrophysics 617 (settembre 2018): A93. http://dx.doi.org/10.1051/0004-6361/201833088.
Testo completoAbstract (sommario):
In a two-planet system, a topological boundary that is created by Sundman (1912, Acta Math., 36, 105) inequality can forbid close encounters between the two planets for an infinite time. A system is said to be Hill stable if it verifies this topological condition. Hill stability is widely used in the study of extrasolar planet dynamics. However, the coplanar and circular orbit approximation is often used. In this paper, we explain how the Hill stability can be understood in the framework of angular momentum deficit (AMD). In the secular approximation, AMD allows us to discriminate between a priori stable systems and systems for which a more in-depth dynamical analysis is required. We show that the general Hill stability criterion can be expressed as a function of only semimajor axes, masses, and total AMD of the system. The proposed criterion is only expanded in the planets-to-star mass ratio ε and not in the semimajor axis ratio, eccentricities, nor the mutual inclination. Moreover, the expansion in ε remains excellent up to values of about 10−3 even for two planets with very different mass values. We performed numerical simulations in order to highlight the sharp change of behavior between Hill stable and Hill unstable systems. We show that Hill stable systems tend to be very regular, whereas Hill unstable systems often lead to rapid planet collisions. We also note that Hill stability does not provide protection from the ejection of the outer planet.
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Siahaan, Andysah Putera Utama. "Dynamic Key Matrix of Hill Cipher Using Genetic Algorithm". International Journal of Advances in Applied Sciences 6, n. 4 (1 dicembre 2017): 313. http://dx.doi.org/10.11591/ijaas.v6.i4.pp313-318.
Testo completoAbstract (sommario):
The matrix in Hill Cipher was designed to perform encryption and decryption. Every column and row must be inserted by integer numbers. But, not any key that can be given to the matrix used for the process. The wrong determinant result cannot be used in the process because it produces the incorrect plaintext when doing the decryption after the encryption. Genetic algorithms offer the optimized way to determine the key used for encryption and decryption on the Hill Cipher. By determining the evaluation function in the genetic algorithm, the key that fits the composition will be obtained. By implementing this algorithm, the search of the key on the Hill Cipher will be easily done without spending too much time. Genetic algorithms do well if it is combined with Hill Cipher.
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Zou, Jingjing, Richard A. Davis e Gennady Samorodnitsky. "EXTREME VALUE ANALYSIS WITHOUT THE LARGEST VALUES: WHAT CAN BE DONE?" Probability in the Engineering and Informational Sciences 34, n. 2 (30 gennaio 2019): 200–220. http://dx.doi.org/10.1017/s0269964818000542.
Testo completoAbstract (sommario):
AbstractIn this paper, we are concerned with the analysis of heavy-tailed data when a portion of the extreme values is unavailable. This research was motivated by an analysis of the degree distributions in a large social network. The degree distributions of such networks tend to have power law behavior in the tails. We focus on the Hill estimator, which plays a starring role in heavy-tailed modeling. The Hill estimator for these data exhibited a smooth and increasing “sample path” as a function of the number of upper order statistics used in constructing the estimator. This behavior became more apparent as we artificially removed more of the upper order statistics. Building on this observation we introduce a new version of the Hill estimator. It is a function of the number of the upper order statistics used in the estimation, but also depends on the number of unavailable extreme values. We establish functional convergence of the normalized Hill estimator to a Gaussian process. An estimation procedure is developed based on the limit theory to estimate the number of missing extremes and extreme value parameters including the tail index and the bias of Hill's estimator. We illustrate how this approach works in both simulations and real data examples.
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Romelic, Jovan, Tatjana Pivac e Kristina Kosic. "Natural resources in the function of the development of tourism of Titel and Titel hill". Glasnik Srpskog geografskog drustva 88, n. 4 (2008): 71–79. http://dx.doi.org/10.2298/gsgd0804071r.
Testo completoAbstract (sommario):
Titel is the largest and the most interesting settlement in the foothill of Titel hill, according to its area/expanse it is small, but the loess plateau in Serbia. It has the most characteristic position of all Backa settlements in Potisje. It is located in the place where Titel hill is the closest to loess strata in Srem in Fruska gora and where there are the narrowest alluvial planes of the two biggest rivers Danube and Tisa. From naturalgeographical point of view this is very complex and for tourists very interesting area. This fact is especially affected by natural potentials found in geomorphologic, hydrographic and biogeography resources. Natural potentials offer possibility for the development of different kinds of tourism which should be raised to a higher level. For now tourism in Titel has regional contractive zone.
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Haseong Kim e E. Gelenbe. "Stochastic Gene Expression Modeling with Hill Function for Switch-Like Gene Responses". IEEE/ACM Transactions on Computational Biology and Bioinformatics 9, n. 4 (luglio 2012): 973–79. http://dx.doi.org/10.1109/tcbb.2011.153.
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Djakov, Plamen, e Boris Mityagin. "Combinatorial Identities Related to Eigen-Function Decompositions of Hill operators: Open Questions". Integral Equations and Operator Theory 75, n. 1 (27 novembre 2012): 7–12. http://dx.doi.org/10.1007/s00020-012-2016-2.
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Lo, Gane Samb, Modou Ngom e Moumouni Diallo. "Extremes, Extremal Index Estimation, Records, Moment Problem for the Pseudo-Lindley Distribution and Applications". European Journal of Pure and Applied Mathematics 13, n. 4 (31 ottobre 2020): 739–57. http://dx.doi.org/10.29020/nybg.ejpam.v13i4.3834.
Testo completoAbstract (sommario):
The pseudo-Lindley distribution which was introduced in Zeghdoudi and Nedjar (2016) is studied with regards to it upper tail. In that regard, and when the underlying distribution function follows the Pseudo-Lindley law, we investigate the the behavior of its values, the asymptotic normality of the Hill estimator and the double-indexed generalized Hill statistic process (Ngom and Lo, 2016), the asymptotic normality of the records values and the the moment problem.
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Appiah, S. T., Albert Buabeng e B. Odoi. "Comparative Study of Mathematical Models for Ghana’s Gold Production". Ghana Mining Journal 18, n. 1 (28 giugno 2018): 78–83. http://dx.doi.org/10.4314/gm.v18i1.10.
Testo completoAbstract (sommario):
Sigmoid functions were used to approximate the cumulative gold production in Ghana. The functions examined were the logistic, Gompertz, Gaussian, Probit and the Hill, which were then used to predict into the future. Although all the five approximated models gave a good estimation of the reality, the Gompertz function was identified to give the best approximation of the observed trend of gold production in Ghana. The model was selected based on its high proportion of variance explained (R2 = 0.9402) as well as having the least value in terms of error (RMSE) and information loss (AIC). The model suggested that gold production could escalate to a level of 7040813 Oz in the future. It also showed that, industrial scale production of gold should be possible even after the year 2050 provided the current upward trend of gold production in Ghana continues. Keywords: Sigmoid, Logistic, Gompertz, Gaussian, Probit, Hill, Gold
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Soulios, G. "SPRINGS (CLASSIFICATION, FUNCTION, CAPTURING)". Bulletin of the Geological Society of Greece 43, n. 1 (19 gennaio 2017): 196. http://dx.doi.org/10.12681/bgsg.11174.
Testo completoAbstract (sommario):
Todd, K (1980) proposed the following definition for springs: “a concentrated discharge of groundwater that emerges on the ground as a stream of water that flows freely”. Spring is distinguished from water leak that is a normally diffused but extended (linear or 2D) slower movement of groundwater towards the ground surface. Uprush is every groundwater emergence on the ground surface or through the bed of water bodies (river, lake, sea). In the context of hydrogeology springs and uprushes in general are in fact “overflows” of aquifers; hence they serve as aquifer discharge mechanisms. Springs emerge at the cross section of groundwater level with the topographic relief. Springs are a strong evidence of rich groundwater potential. A big number of small springs emerging at the margins of basins or the hill slopes are an evidence of a shallow aquifer of low hydraulic conductivity. On the contrary, big springs emerging at the bottom of valleys, i.e. the basic geomorphological level, are an indication of a high potential aquifer characterized by considerable values of hydraulic conductivity.
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Li, An Lin, Huan Ping Zhang, Hui Du, Yang Li e Hai Xiang Song. "The Application of Improved Hill-Climbing in the Multiple Nonlinear Regression". Advanced Materials Research 396-398 (novembre 2011): 2353–56. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.2353.
Testo completoAbstract (sommario):
The hill-climbing has been improved by using the percentage random step and by changing variable values instantly, which is under the condition of an improvement in the objective function having been made by a step forward of a variable in a certain direction, and the improved hill-climbing has been used to solve nonlinear regression problems , and the specific algorithm steps is given, and it has been validated with satisfactory results by using practical examples.
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Noakes, Timothy D., Juha E. Peltonen e Heikki K. Rusko. "Evidence that a central governor regulates exercise performance during acute hypoxia and hyperoxia". Journal of Experimental Biology 204, n. 18 (15 settembre 2001): 3225–34. http://dx.doi.org/10.1242/jeb.204.18.3225.
Testo completoAbstract (sommario):
SUMMARY An enduring hypothesis in exercise physiology holds that a limiting cardiorespiratory function determines maximal exercise performance as a result of specific metabolic changes in the exercising skeletal muscle, so-called peripheral fatigue. The origins of this classical hypothesis can be traced to work undertaken by Nobel Laureate A. V. Hill and his colleagues in London between 1923 and 1925. According to their classical model, peripheral fatigue occurs only after the onset of heart fatigue or failure. Thus, correctly interpreted, the Hill hypothesis predicts that it is the heart, not the skeletal muscle, that is at risk of anaerobiosis or ischaemia during maximal exercise. To prevent myocardial damage during maximal exercise, Hill proposed the existence of a ‘governor’ in either the heart or brain to limit heart work when myocardial ischaemia developed. Cardiorespiratory function during maximal exercise at different altitudes or at different oxygen fractions of inspired air provides a definitive test for the presence of a governor and its function. If skeletal muscle anaerobiosis is the protected variable then, under conditions in which arterial oxygen content is reduced, maximal exercise should terminate with peak cardiovascular function to ensure maximum delivery of oxygen to the active muscle. In contrast, if the function of the heart or some other oxygen-sensitive organ is to be protected, then peak cardiovascular function will be higher during hyperoxia and reduced during hypoxia compared with normoxia. This paper reviews the evidence that peak cardiovascular function is reduced during maximal exercise in both acute and chronic hypoxia with no evidence for any primary alterations in myocardial function. Since peak skeletal muscle electromyographic activity is also reduced during hypoxia, these data support a model in which a central, neural governor constrains the cardiac output by regulating the mass of skeletal muscle that can be activated during maximal exercise in both acute and chronic hypoxia.
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Ngom, Modou, e Gane Samb Lo. "A Double-indexed Functional Hill Process and Applications". Journal of Mathematics Research 8, n. 4 (27 luglio 2016): 144. http://dx.doi.org/10.5539/jmr.v8n4p144.
Testo completoAbstract (sommario):
<div>Let $X_{1,n} \leq .... \leq X_{n,n}$ be the order statistics associated with a sample $X_{1}, ...., X_{n}$ whose pertaining distribution function (\textit{df}) is $F$. We are concerned with the functional asymptotic behaviour of the sequence of stochastic processes</div><div> </div><div>\begin{equation}<br />T_{n}(f,s)=\sum_{j=1}^{j=k}f(j)\left( \log X_{n-j+1,n}-\log<br />X_{n-j,n}\right)^{s} , \label{fme}<br />\end{equation}</div><div> </div><div>indexed by some classes $\mathcal{F}$ of functions $f:\mathbb{N}%^{\ast}\longmapsto \mathbb{R}_{+}$ and $s \in ]0,+\infty[$ and where $k=k(n)$ satisfies</div><div> </div><div>\begin{equation*}<br />1\leq k\leq n,k/n\rightarrow 0\text{ as }n\rightarrow \infty .<br />\end{equation*}</div><div> </div><div>We show that this is a stochastic process whose margins generate estimators of the extreme value index when $F$ is in the extreme domain of attraction. We focus in this paper on its finite-dimension asymptotic law and provide a class of new estimators of the extreme value index whose performances are compared to analogous ones. The results are next particularized for one explicit class $\mathcal{F}$.</div>
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Bulatović, Luka, Anđela Mijanović, Balša Asanović, Nikola Trajković e Vladimir Božović. "Automated cryptanalysis of substitution cipher using Hill climbing with well designed heuristic function". Mathematica Montisnigri 44 (2019): 135–43. http://dx.doi.org/10.20948/mathmon-2019-44-11.
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Pruss, Shelley D. "Selection of natal dens by the swift fox (Vulpes velox) on the Canadian prairies". Canadian Journal of Zoology 77, n. 4 (15 settembre 1999): 646–52. http://dx.doi.org/10.1139/z99-001.
Testo completoAbstract (sommario):
The location and physical characteristics of 32 occupied swift fox (Vulpes velox) natal/rearing dens and 33 unoccupied sites in southeastern Alberta and southwestern Saskatchewan, Canada, were compared in 1991 and 1992. Comparisons between occupied and unoccupied sites were restricted to eight habitat variables that described the orientation of each den entrance, mean height of old and new grass, number of holes in each den complex, den position and slope (i.e., incline of the land) in relation to hills, and distance to the nearest roadway and water source. Two-sample t tests and Mann-Whitney U tests indicated that occupied sites were located on the tops of hills, close to roads, and in places where old grass was significantly higher than at unoccupied sites. Den entrance angles did not differ between occupied and unoccupied sites. A stepwise discriminant function analysis identified five potential discriminators of occupied and unoccupied sites (i.e., position on a hill, height of new grass, distance to water, distance to roads, and slope). Den position was the variable that discriminated most strongly between occupied and unoccupied sites. Occupied sites were located predominantly on the tops of hills. The quadratic discriminant function had an overall classification success of 83.1%. Based on the five habitat variables, the discriminant function model correctly classified 28 of the 32 occupied sites as being occupied (87.5%) and 26 of the 33 unoccupied sites as being unoccupied (78.8%). The habitat variables identified by the discriminant function model may be a useful tool for selecting and modifying release-site characteristics and creating more realistic live-rearing facilities.
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Niedźwiadek, Rafał, e Andrzej Rozwałka. "The stronghold on Kirkut Hill in Lublin. The state of recognition of the remains of the former stronghold and its role in the medieval Lublin agglomeration". Analecta Archaeologica Ressoviensia 15 (2020): 165–85. http://dx.doi.org/10.15584/anarres.2020.15.9.
Testo completoAbstract (sommario):
The aim of the article is to present the state of the research conducted on the remains of a medieval stronghold on Grodzisko Hill, also known as Kirkut Hill (due to the Jewish cemetery from the late Middle Ages and early modern period located on its top), as well as to show the latest approach to dating the remains of the stronghold and its role in the medieval Lublin agglomeration. Archaeological research carried out on the hill and at its foot in the 1960s and 1970s was of limited range due to the existence of the Jewish cemetery. However, it can be considered that they provided an amount of data that enables the reconstruction of stratigraphy of the stronghold and recognition of the structure of its rampart running along the edge of the hill. After many discussions, both among historians and Lublin archaeologists, a certain consensus regarding the chronology and the function of the former stronghold on Grodzisko Hill has now been reached. It seems that it was in the 13th century that the stronghold was built and, then, before the century ended, it was destroyed. It coexisted with an older structure – probably built in the 12th century – namely the castellan stronghold on Zamkowe Hill. Recent research indicates that during the second half of 13th century, or at the turn of the 13th and 14th centuries, a new line of ramparts was built on Staromiejskie Hill. This is how three parts of the Lublin agglomeration were distinguished. Perhaps, in this structure, the stronghold on Kirkut Hill could have functioned as a guard post for a part of the long-distance route located in the area of today’s Kalinowszczyzna Street. The 13th century, and especially its second half, was the time of numerous Yotvingian, Lithuanian, Mongolian, Ruthenian and Tatar invasions.
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Matsebula, Lindiwe Fortunate. "Shoulder Function Following Latarjet Procedure for Recurrent Anterior Shoulder Instability". Journal of Orthopaedics & Bone Disorders 5, n. 1 (2021): 1–8. http://dx.doi.org/10.23880/jobd-16000205.
Testo completoAbstract (sommario):
Introduction: Anterior shoulder dislocation and recurrent glenohumeral instability is very common in the young active population. It is usually caused by trauma, and often compounded by associated bony Bankart and Hill-Sachs lesions, which distort the anatomy. This causes instability and dysfunction of the joint and these can be addressed by, amongst others, a Latarjet surgical procedure. Hypothesis: We hypothesize that since the Latarjet procedure results in stability and good functional outcome, our results are expected to compare favourably to the rest of the published literature. Methods: A retrospective study of 31 patients treated with the Latarjet procedure at Helen Joseph hospital, Johannesburg South Africa was undertaken during the period of January 2005 to December 2013. The minimum follow up was 6 months. Stability was assessed looking at re-dislocation rate and the clinical functional outcome was measured using the Constant Score. Results: There were no shoulder re-dislocations and the mean Constant score was 85.35. 74% had a Constant Score above 80. 68% were pain free and 61% had normal activities of daily living while 68% had a full range of motion and 68% had full power. Conclusion: The Latarjet results in stability and good functional outcome. In our patient cohort, the Latarjet procedure provided reliable stability to the shoulder joint. Pain was alleviated, shoulder muscle power was preserved, range of shoulder motion was restored and patients did return to pre injury activities of daily living.
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Spudich, Paul, Margaret Hellweg e W. H. K. Lee. "Directional topographic site response at Tarzana observed in aftershocks of the 1994 Northridge, California, earthquake: Implications for mainshock motions". Bulletin of the Seismological Society of America 86, n. 1B (1 febbraio 1996): S193—S208. http://dx.doi.org/10.1785/bssa08601bs193.
Testo completoAbstract (sommario):
Abstract The Northridge earthquake caused 1.78 g acceleration in the east-west direction at a site in Tarzana, California, located about 6 km south of the mainshock epicenter. The accelerograph was located atop a hill about 15-m high, 500-m long, and 130-m wide, striking about N78°E. During the aftershock sequence, a temporary array of 21 three-component geophones was deployed in six radial lines centered on the accelerograph, with an average sensor spacing of 35 m. Station C00 was located about 2 m from the accelerograph. We inverted aftershock spectra to obtain average relative site response at each station as a function of direction of ground motion. We identified a 3.2-Hz resonance that is a transverse oscillation of the hill (a directional topographic effect). The top/base amplification ratio at 3.2 Hz is about 4.5 for horizontal ground motions oriented approximately perpendicular to the long axis of the hill and about 2 for motions parallel to the hill. This resonance is seen most strongly within 50 m of C00. Other resonant frequencies were also observed. A strong lateral variation in attenuation, probably associated with a fault, caused substantially lower motion at frequencies above 6 Hz at the east end of the hill. There may be some additional scattered waves associated with the fault zone and seen at both the base and top of the hill, causing particle motions (not spectral ratios) at the top of the hill to be rotated about 20° away from the direction transverse to the hill. The resonant frequency, but not the amplitude, of our observed topographic resonance agrees well with theory, even for such a low hill. Comparisons of our observations with theoretical results indicate that the 3D shape of the hill and its internal structure are important factors affecting its response. The strong transverse resonance of the hill does not account for the large east-west mainshock motions. Assuming linear soil response, mainshock east-west motions at the Tarzana accelerograph were amplified by a factor of about 2 or less compared with sites at the base of the hill. Probable variations in surficial shear-wave velocity do not account for the observed differences among mainshock acceleration observed at Tarzana and at two different sites within 2 km of Tarzana.
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Li, Li-Li, e Fu-Hu Liu. "Kinetic Freeze-Out Properties from Transverse Momentum Spectra of Pions in High Energy Proton-Proton Collisions". Physics 2, n. 2 (12 giugno 2020): 277–308. http://dx.doi.org/10.3390/physics2020015.
Testo completoAbstract (sommario):
Transverse momentum spectra of negative and positive pions produced at mid-(pseudo)rapidity in inelastic or non-single-diffractive proton-proton collisions over a center-of-mass energy, s , range from a few GeV to above 10 TeV are analyzed by the blast-wave fit with Boltzmann (Tsallis) distribution. The blast-wave fit results are well fitting to the experimental data measured by several collaborations. In a particular superposition with Hagedorn function, both the excitation functions of kinetic freeze-out temperature ( T 0 ) of emission source and transverse flow velocity ( β T ) of produced particles obtained from a given selection in the blast-wave fit with Boltzmann distribution have a hill at s ≈ 10 GeV, a drop at dozens of GeV, and then an increase from dozens of GeV to above 10 TeV. However, both the excitation functions of T 0 and β T obtained in the blast-wave fit with Tsallis distribution do not show such a complex structure, but a very low hill. In another selection for the parameters or in the superposition with the usual step function, T 0 and β T increase generally quickly from a few GeV to about 10 GeV and then slightly at above 10 GeV, there is no such the complex structure, when also studying nucleus-nucleus collisions.
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Kearney, Kalyn M., Joel B. Harley e Jennifer A. Nichols. "Classifying muscle parameters with artificial neural networks and simulated lateral pinch data". PLOS ONE 16, n. 9 (2 settembre 2021): e0255103. http://dx.doi.org/10.1371/journal.pone.0255103.
Testo completoAbstract (sommario):
Objective Hill-type muscle models are widely employed in simulations of human movement. Yet, the parameters underlying these models are difficult or impossible to measure in vivo. Prior studies demonstrate that Hill-type muscle parameters are encoded within dynamometric data. But, a generalizable approach for estimating these parameters from dynamometric data has not been realized. We aimed to leverage musculoskeletal models and artificial neural networks to classify one Hill-type muscle parameter (maximum isometric force) from easily measurable dynamometric data (simulated lateral pinch force). We tested two neural networks (feedforward and long short-term memory) to identify if accounting for dynamic behavior improved accuracy. Methods We generated four datasets via forward dynamics, each with increasing complexity from adjustments to more muscles. Simulations were grouped and evaluated to show how varying the maximum isometric force of thumb muscles affects lateral pinch force. Both neural networks classified these groups from lateral pinch force alone. Results Both neural networks achieved accuracies above 80% for datasets which varied only the flexor pollicis longus and/or the abductor pollicis longus. The inclusion of muscles with redundant functions dropped model accuracies to below 30%. While both neural networks were consistently more accurate than random guess, the long short-term memory model was not consistently more accurate than the feedforward model. Conclusion Our investigations demonstrate that artificial neural networks provide an inexpensive, data-driven approach for approximating Hill-type muscle-tendon parameters from easily measurable data. However, muscles of redundant function or of little impact to force production make parameter classification more challenging.