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Статті в журналах з теми "Higher-order structural model"
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Lee, Craig, Rob Hallak, and Shruti R. Sardeshmukh. "Innovation, entrepreneurship, and restaurant performance: A higher-order structural model." Tourism Management 53 (April 2016): 215–28. http://dx.doi.org/10.1016/j.tourman.2015.09.017.
Повний текст джерела
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Compagnoni, Adriana B., and Benjamin C. Pierce. "Higher-order intersection types and multiple inheritance." Mathematical Structures in Computer Science 6, no. 5 (October 1996): 469–501. http://dx.doi.org/10.1017/s0960129500070043.
Повний текст джерелаАнотація:
We study a natural generalization of SystemFωwith intersection types, establishing basic structural properties and constructing a semantic model based on partial equivalence relations to prove the soundness of typing. As an application of this calculus, we define a simple typed model of object-oriented programming with multiple inheritance.
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Zhan, Peida, Wenchao Ma, Hong Jiao, and Shuliang Ding. "A Sequential Higher Order Latent Structural Model for Hierarchical Attributes in Cognitive Diagnostic Assessments." Applied Psychological Measurement 44, no. 1 (March 4, 2019): 65–83. http://dx.doi.org/10.1177/0146621619832935.
Повний текст джерелаАнотація:
The higher-order structure and attribute hierarchical structure are two popular approaches to defining the latent attribute space in cognitive diagnosis models. However, to our knowledge, it is still impossible to integrate them to accommodate the higher-order latent trait and hierarchical attributes simultaneously. To address this issue, this article proposed a sequential higher-order latent structural model (LSM) by incorporating various hierarchical structures into a higher-order latent structure. The feasibility of the proposed higher-order LSM was examined using simulated data. Results indicated that, in conjunction with the deterministic-inputs, noisy “and” gate model, the sequential higher-order LSM produced considerable improvement in person classification accuracy compared with the conventional higher-order LSM, when a certain attribute hierarchy existed. An empirical example was presented as well to illustrate the application of the proposed LSM.
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Watson-Brown, Natalie, Bridie Scott-Parker, and Teresa Senserrick. "Higher order training supporting competence, autonomy, relatedness (HOT-CAR): A model to improve learner drivers' higher order skills." Transportation Research Part F: Traffic Psychology and Behaviour 80 (July 2021): 79–89. http://dx.doi.org/10.1016/j.trf.2021.03.013.
Повний текст джерела
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Pavlov, I. S., and A. V. Muravieva. "A 3D HIGHER-ORDER GRADIENT MODEL FOR A HALF-SPACE GEOMEDIUM." Problems of Strength and Plasticity 84, no. 4 (2022): 480–92. http://dx.doi.org/10.32326/1814-9146-2022-84-4-480-492.
Повний текст джерелаАнотація:
In this paper, a structural model of a geomedium (a soil) is proposed in the form of a simple cubic lattice of spherical particles (blocks) possessing three translational and three rotational degrees of freedom. The force and couple interactions between the particles are modeled by elastic springs of five types. A long-wavelength continuum mathematical model of the soil has been elaborated by the method of structural modeling. An analytical relationship between its macroconstants and microstructure parameters has been found. It is shown that the obtained model differs from the model of the reduced Cosserat medium, which is often employed to describe granular media. In the low-frequency approximation, it can be reduced to the equations of the higher-order gradient theory of elasticity, which are similar to the Cosserat continuum equations with constrained rotation of particles. These equations contain both terms with mixed derivatives with respect to time and coordinate that take into account the inertia of particles rotation in the medium and lead to the wave dispersion, and terms proportional to the spatial derivatives of the fourth order, which describe the contribution of stresses caused by bending of the medium to the potential energy. In the framework of the higher-order gradient model, expressions for the classical and couple stresses in the considered geomedium are found. Boundary conditions are set that consist in the absence of normal and shear stresses on the upper platform of a half-space medium. A condition for the microstructure parameters has been revealed, under which the couple stresses can be neglected. The proposed here higher-order gradient model with given boundary conditions can be used to investigate the propagation and interaction of elastic waves in a semi-infinite geomedium, which are generated by the high-speed movement of trains, as well as to identify and study potentially dangerous effects caused by such movement.
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Haack, Alexander, Justine R. Bissonnette, Christian Ieritano, and W. Scott Hopkins. "Improved First-Principles Model of Differential Mobility Using Higher Order Two-Temperature Theory." Journal of the American Society for Mass Spectrometry 33, no. 3 (January 31, 2022): 535–47. http://dx.doi.org/10.1021/jasms.1c00354.
Повний текст джерела
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Innes, Graeme. "Higher-order structural constraints for improved optimization of nonuniform helical antennas." Facta universitatis - series: Electronics and Energetics 33, no. 4 (2020): 531–51. http://dx.doi.org/10.2298/fuee2004531i.
Повний текст джерелаАнотація:
The objective is to improve the linear constraints for optimizing the helical structure (radius and pitch of the conductor winding) of nonuniform helical antennas for desired characteristics such as signal gain or bandwidth. Presented below are equations that allow various higher-order structural constraints to be used in such optimizations. Their efficacy is demonstrated by analogy, using data for a fully optimized Yagi-Uda antenna, before being applied to data available for helical designs. The comparisons confirm the general validity of the higher-order equations to model some of the most advanced antennas produced to date. A simple calculus-of-variations test confirms that an improved optimization is possible by adding curvature terms to previously published linear constraints.
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Krüger, Cristiane, and Italo Fernando Minello. "Structural model of employee behavior measurement." Revista de Negócios 24, no. 1 (June 5, 2019): 35. http://dx.doi.org/10.7867/1980-4431.2019v24n1p35-56.
Повний текст джерелаАнотація:
The traditional methods of evaluating entrepreneurial behavior carry a degree of uncertainty and subjectivity with several uncontrollable independent variables. Faced with this fragility, the modeling of structural equations can be a tool that contributes to the understanding of this behavior. In order to contribute in this direction, this study aimed to develop a structural model for measuring entrepreneurial behavior based on behavioral characteristics and entrepreneurial intent. The research is applied, quantitative, descriptive and exploratory. In order to satisfy the problem raised, data collection instruments already validated were used. The sample consisted of 2,519 respondents. The internal consistency of the scales proved to be reliable for the measurement and evaluation of the constructs. In the descriptive analysis it was identified that the achievement dimension obtained higher score, moreover, more than 90% of the participants present entrepreneurial behavioral characteristics and intend to undertake. Then, behavioral characteristics and entrepreneurial intention were related by developing a structural model for entrepreneurial behavior. It was concluded that the model is apt to measure entrepreneurial behavior. The research was limited to the construction of a model of measurement of entrepreneurial behavior from the instruments answered by undergraduate students from a public higher education institution. Future studies can expand the constructs addressed in the structural model, as well as be replicated in other institutions of higher or basic education in order to compare, deepen and new findings, in addition to considering a longitudinal follow-up. The originality of the study lies in the development of a structural model for measuring entrepreneurial behavior.
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Fu, Bo, and Fu-Tai Zhang. "A dual-explicit model-based integration algorithm with higher-order accuracy for structural dynamics." Applied Mathematical Modelling 110 (October 2022): 513–41. http://dx.doi.org/10.1016/j.apm.2022.06.005.
Повний текст джерела
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Karpik, Anna, Francesco Cosco, and Domenico Mundo. "Higher-Order Hexahedral Finite Elements for Structural Dynamics: A Comparative Review." Machines 11, no. 3 (February 24, 2023): 326. http://dx.doi.org/10.3390/machines11030326.
Повний текст джерелаАнотація:
The finite element method (FEM) is widely used in many engineering applications. The popularity of FEM led to the development of several variants of formulations, and hexahedral meshes surged as one of the most computationally effective. After briefly reviewing the reasons and advantages behind the formulation of increasing order elements, including the serendipity variants and the associated reduced integration schemes, a systematic comparison of the most common hexahedral formulations is presented. A numerical benchmark was used to assess convergency rates and computational efficiencies when solving the eigenvalue problem for linear dynamic analysis. The obtained results confirmed the superior performances of the higher-order brick element formulations. In terms of computational efficiency, defined as the ratio between achievable accuracy and computational execution time, quadratic or cubic formulations exhibited the best results for the stages of FE model assembly and solution computation, respectively.
Дисертації з теми "Higher-order structural model"
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Niblett, Samuel Peter. "Higher order structure in the energy landscapes of model glass formers." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/277582.
Повний текст джерелаАнотація:
The study of supercooled liquids and glasses remains one of the most divisive and divided fields in modern physics. Despite a vast amount of effort and research time invested in this topic, the answers to many central questions remain disputed and incomplete. However, the link between the behaviour of supercooled liquids and their energy landscapes is well established and widely accepted. Understanding this link would be a key step towards resolving many of the mysteries and controversies surrounding the glass transition. Therefore the study of glassy energy landscapes is an important area of research. In this thesis, I report some of the most detailed computational studies of glassy potential energy landscapes ever performed. Using geometry optimisation techniques, I have sampled the local minima and saddle points of the landscapes for several supercooled liquids to analyse their dynamics and thermodynamics. Some of my analysis follows previous work on the binary Lennard-Jones fluid (BLJ), a model atomic liquid. BLJ is a fragile glass former, meaning that its transport coefficients have super-Arrhenius temperature dependence, rather than the more usual Arrhenius behaviour exhibited by strong liquids. The difference in behaviour between these two classes of liquid has previously been attributed to differing degrees of structure in the relevant energy landscapes. I have studied models for both fragile and strong glass formers: the molecular liquid ortho-terphenyl (OTP) and viscous silica (SiO$_{2}$) respectively. My results for OTP agree closely with trends observed for BLJ, suggesting that the same diffusion mechanism is applicable to fragile molecular liquids as well as to atomic. However, the dynamics and energy landscape of OTP are made complicated by the molecular orientational degrees of freedom, making the analysis more challenging for this system. Dynamics of BLJ, OTP and silica are all dominated by cage-breaking events: structural rearrangements in which atoms change their nearest neighbours. I propose a robust and general method to identify cage breaks for small rigid molecules, and compare some properties of cage breaks between strong and fragile systems. The energy landscapes of BLJ and OTP both display hierarchical ordering of potential energy minima into metabasins. These metabasins can be detected by the cage-breaking method. It has previously been suggested that metabasins are responsible for super-Arrhenius behaviour, and are absent from the landscapes of strong liquids such as SiO2. My results indicate that metabasins are present on the silica landscape, but that they each contain fewer minima than metabasins in BLJ or OTP. Metabasins are associated with anticorrelated particle motion, mediated by reversed transitions between minima of the potential energy landscape. I show that accounting for time-correlation of particle displacement vectors is essential to describe super-Arrhenius behaviour in BLJ and OTP, but also required to reproduce strong behaviour in silica. I hypothesise that the difference between strong and fragile liquids arises from a longer correlation timescale in the latter case, and I suggest a number of ways in which this proposition could be tested. I have investigated the effect on the landscape of freezing the positions of some particles in a BLJ fluid. This “pinning” procedure induces a dynamical crossover that has been described as an equilibrium “pinning transition”, related to the hypothetical ideal glass transition. I show that the pinning transition is related to (and probably caused by) a dramatic change in the potential energy landscape. Pinning a large fraction of the particles in a supercooled liquid causes its energy landscape to acquire global structure and hence structure-seeking behaviour, very different from the landscape of a typical supercooled liquid. I provide a detailed description of this change in structure, and investigate the mechanism underlying it. I introduce a new algorithm for identifying hierarchical organisation of a landsape, which uses concepts related to the pinning transition but is applicable to unpinned liquids as well. This definition is complementary to metabasins, but the two methods often identify the same higher-order structures. The new “packings” algorithm offers a route to test thermodynamic theories of the glass transition in the context of the potential energy landscape. Over the course of this thesis, I discuss several different terms and methods to identify higher-order structures in the landscapes of model glass formers, and investigate how this organisation varies between different systems. Although little variation is immediately apparent between most glassy landscapes, deeper analysis reveals a surprising diversity, which has important implications for dynamical behaviour in the vicinity of the glass transition.
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Collins, Justin A. Valentine Jerry. "Higher-order thinking in the high-stakes accountability era linking student engagement and test performance /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2009. http://hdl.handle.net/10355/6769.
Повний текст джерелаАнотація:
The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on March 25, 2010). Thesis advisor: Dr. Jerry W. Valentine. Vita. Includes bibliographical references.
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Giorgidze, George. "First-class models : on a noncausal language for higher-order and structurally dynamic modelling and simulation." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/12554/.
Повний текст джерелаАнотація:
The field of physical modelling and simulation plays a vital role in advancing numerous scientific and engineering disciplines. To cope with the increasing size and complexity of physical models, a number of modelling and simulation languages have been developed. These languages can be divided into two broad categories: causal and noncausal. Causal languages express a system model in terms of directed equations. In contrast, a noncausal model is formulated in terms of undirected equations. The fact that the causality can be left implicit makes noncausal languages more declarative and noncausal models more reusable. These are considered to be crucial advantages in many physical domains. Current, mainstream noncausal languages do not treat equational models as first-class values; that is, a model cannot be parametrised on other models or generated at simulation runtime. This results in very limited higher-order and structurally dynamic modelling capabilities, and limits the expressiveness and applicability of noncausal languages. This thesis is about a novel approach to the design and implementation of noncausal languages with first-class models supporting higher-order and structurally dynamic modelling. In particular, the thesis presents a language that enables: (1) higher-order modelling capabilities by embedding noncausal models as first-class entities into a functional programming language and (2) efficient simulation of noncausal models that are generated at simulation runtime by runtime symbolic processing and just-in-time compilation. These language design and implementation approaches can be applied to other noncausal languages. This thesis provides a self-contained reference for such an undertaking by defining the language semantics formally and providing an in-depth description of the implementation. The language provides noncausal modelling and simulation capabilities that go beyond the state of the art, as backed up by a range of examples presented in the thesis, and represents a significant progress in the field of physical modelling and simulation.
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Nishida, Pedro Pio Rosa. "Estruturas inteligentes aplicadas ao controle ativo de ruído de alta ordem em dutos." Universidade Federal de Uberlândia, 2012. https://repositorio.ufu.br/handle/123456789/14908.
Повний текст джерелаАнотація:
Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorIn this study the possible use of smart structures for noise control in a higher order acoustic duct was considered. The best option for this control was the use of axial splitters in the duct in order to prevent higher order mode propagation. It is possible to perform the active noise control in each splitter section by using a single channel control system. The use of smart structures takes advantage of the splitter plate and uses it as the control source, which substitutes the traditional loudspeakers used in active noise control systems. In order to evaluate the possibility of the noise control using smart structures, an analytical model of a thin plate with piezoelectric actuators was built then the acoustic field generated by this vibrating structure inside of the duct was obtained. However, to obtain the acoustic field inside an splitted duct, a numerical method such as the Component Mode Synthesis has to be used. Using the equation of the acoustic field generated in the duct by the plate, it was possible to obtain the acoustic field inside the splitted duct. After that, the active noise control simulations for harmonic excitations were performed and the influence of the size of the plate excited by the PZT actuators was studied. Finally the active control for random noise was simulated, in which the number of actuators in the plate was changed. In conclusion, it is possible to say that the smart structures can be used in active noise control of ducts with splitters and the advantages and disadvantages of the conveyed technique were presented.
Neste trabalho, foi estudada a proposta da utilização de estruturas inteligentes para o controle de ruído em um duto acústico com propagação de modos de alta ordem. A técnica mais adequada para este controle foi o particionamento do duto a fim de planificar as ondas que se propagam. Nesta região particionada, é possível realizar o controle ativo de ruído utilizando apenas um sensor e um atuador para cada lado da partição. A aplicação das estruturas inteligentes é proposta no sentido de aproveitar a placa particionadora para que, com a sua vibração, atuará como a fonte secundária necessária para o controle. Para a avaliação da possibilidade de controle utilizando esta técnica, primeiramente foi modelado o comportamento de uma placa instrumentada com atuadores piezoelétricos e, em seguida, obtida a modelagem analítica do campo sonoro gerado por uma estrutura vibrante no interior de um duto. Porém, a obtenção do campo acústico em um duto particionado não é facilmente obtido, sendo, então, realizada através da técnica de Síntese Modal de Componentes. Utilizando as equações do duto excitado por uma estrutura vibrante na técnica de síntese modal, foi possível obter campo acústico gerado no interior de um duto particionado. A partir disto, foram realizados simulações de controle ativo de ruído variando o trecho da placa a ser excitado para tons puros e para ruídos de banda estreita. Nesta última situação também foi avaliada a influência da quantidade de atuadores instalados. Concluiu-se deste trabalho que é possível a utilização de estruturas inteligentes no controle ativo de ruído em dutos particionados, sendo apresentadas suas vantagens e desvantagens.
Mestre em Engenharia Mecânica
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Karagiannis, Dionysios. "The bispectrum of Large Scale Structures: modelling, prediction and estimation." Doctoral thesis, Università degli studi di Padova, 2018. http://hdl.handle.net/11577/3427289.
Повний текст джерелаАнотація:
In this thesis we study the higher-order statistics of Large Scale Structures (LSS). In particular, we examine the potential of the bispectrum (Fourier transform of the three-point correlator) of galaxies for both probing the non-linear regime of structure growth and setting constraints on primordial non-Gaussianity.
The starting step is to construct accurate models for the power spectrum (Fourier transform of the two-point correlator) and bispectrum of galaxies by using the predictions of perturbation methods. In addition, the recent developments on the relation between dark matter and galaxy distributions (i.e. bias) are discussed and incorporated into the modelling, in order to have an accurate theoretical formalism on the galaxy formation. In order to build models that are as realistic as possible, we take into account additional non-linear effects, such as redshift space distortions. The analysis is mainly restricted to the large and intermediate scales, where the available perturbation theories have been heavily tested and give predictions that are in agreement with simulation and past LSS surveys. The reasoning for constructing accurate models for the non-linear gravitational evolution of galaxies is that, it is crucial to distinguish the primordial non-Gaussian (PNG) signal from the late time non-linearities.
Furthermore, we investigate forecasted constraints on primordial non-Gaussianity and bias parameters from measurements of galaxy power spectrum and bispectrum in future radio continuum (EMU and SKA) and optical surveys (Euclid, DESI, LSST and SPHEREx). In the galaxy bispectrum modelling, we consider the bias expansion for non-Gaussian initial conditions up to second order, including trispectrum (Fourier transform of the four-point correlator) scale-dependant contributions, originating from the galaxy bias expansion, where for the first time we extend such correction to redshift space. We study the impact of uncertainties in the theoretical modelling of the bispectrum expansion and of redshift space distortions (theoretical errors), showing that they can all affect the final predicted bounds.
We find that the bispectrum generally has a strong constraining power and can lead to improvements up to a factor ~5 over bounds based on the power spectrum alone.
Our results show that constraints for local-type PNG can be significantly improved compared to current limits: future radio (e.g. SKA) and photometric surveys could obtain a measurement error on $f_{NL}^\text{loc}$, $\sigma(f_{NL}^\text{loc}) \approx 0.2-0.3$. More specifically, near future optical spectroscopic surveys, such as Euclid, will also improve over Planck by a factor of a few, while LSST will provide competitive constraints to radio continuum. In the case of equilateral PNG, galaxy bispectrum constraints are very weak, and current constraints could be tightened only if significant improvements in the redshift determinations of large volume surveys could be achieved. For orthogonal non-Gaussianity, expected constraints are comparable to the ones from Planck, e.g. $\sigma(f_{NL}^\text{ortho})\approx18$ for radio surveys.
In the last part of the thesis we development a pipeline that measures the bispectrum from N-body simulations or galaxy surveys, which is based on the modal estimation formalism. This computationally demanding task is reduced from $O(N^6)$ operations to $O(N^3)$, where N is the number of modes per dimension inside the said simulation box or survey. The main idea of the modal estimator is to construct a suitable basis (``modes'') on the domain defined by the triangle condition and decompose on it the desired theoretical or observational bispectrum. This allows for massive data compression, making it an extremely useful tool for future LSS surveys. We show the results of tests performed to improve the performance of the pipeline and the convergence of the modal expansion. In addition, we present the measured bispectrum from a set of simulations with Gaussian initial condition, where the small amount of modes needed to accurately reconstruct the matter bispectrum shows the power of the modal expansion. The effective $f_{NL}$ value, corresponding to the bispectrum of the non-linear gravitational evolution, comes at no computational cost. In order to further test the pipeline, we proceed to measure the bispectrum of a few realisations with non-Gaussian initial conditions of the local type. We show that the modal decomposition can accurately separate the primordial signal, from the late-time non-Gaussianity, and put tight constraints on its amplitude.In this thesis we study the higher-order statistics of Large Scale Structures (LSS). In particular, we examine the potential of the bispectrum (Fourier transform of the three-point correlator) of galaxies for both probing the non-linear regime of structure growth and setting constraints on primordial non-Gaussianity. The starting step is to construct accurate models for the power spectrum (Fourier transform of the two-point correlator) and bispectrum of galaxies by using the predictions of perturbation methods. In addition, the recent developments on the relation between dark matter and galaxy distributions (i.e. bias) are discussed and incorporated into the modelling, in order to have an accurate theoretical formalism on the galaxy formation. In order to build models that are as realistic as possible, we take into account additional non-linear effects, such as redshift space distortions. The analysis is mainly restricted to the large and intermediate scales, where the available perturbation theories have been heavily tested and give predictions that are in agreement with simulation and past LSS surveys. The reasoning for constructing accurate models for the non-linear gravitational evolution of galaxies is that, it is crucial to distinguish the primordial non-Gaussian (PNG) signal from the late time non-linearities. Furthermore, we investigate forecasted constraints on primordial non-Gaussianity and bias parameters from measurements of galaxy power spectrum and bispectrum in future radio continuum (EMU and SKA) and optical surveys (Euclid, DESI, LSST and SPHEREx). In the galaxy bispectrum modelling, we consider the bias expansion for non-Gaussian initial conditions up to second order, including trispectrum (Fourier transform of the four-point correlator) scale-dependant contributions, originating from the galaxy bias expansion, where for the first time we extend such correction to redshift space. We study the impact of uncertainties in the theoretical modelling of the bispectrum expansion and of redshift space distortions (theoretical errors), showing that they can all affect the final predicted bounds. We find that the bispectrum generally has a strong constraining power and can lead to improvements up to a factor ~5 over bounds based on the power spectrum alone. Our results show that constraints for local-type PNG can be significantly improved compared to current limits: future radio (e.g. SKA) and photometric surveys could obtain a measurement error on $f_{NL}^\text{loc}$, $\sigma(f_{NL}^\text{loc}) \approx 0.2-0.3$. More specifically, near future optical spectroscopic surveys, such as Euclid, will also improve over Planck by a factor of a few, while LSST will provide competitive constraints to radio continuum. In the case of equilateral PNG, galaxy bispectrum constraints are very weak, and current constraints could be tightened only if significant improvements in the redshift determinations of large volume surveys could be achieved. For orthogonal non-Gaussianity, expected constraints are comparable to the ones from Planck, e.g. $\sigma(f_{NL}^\text{ortho})\approx18$ for radio surveys. In the last part of the thesis we development a pipeline that measures the bispectrum from N-body simulations or galaxy surveys, which is based on the modal estimation formalism. This computationally demanding task is reduced from $O(N^6)$ operations to $O(N^3)$, where N is the number of modes per dimension inside the said simulation box or survey. The main idea of the modal estimator is to construct a suitable basis (``modes'') on the domain defined by the triangle condition and decompose on it the desired theoretical or observational bispectrum. This allows for massive data compression, making it an extremely useful tool for future LSS surveys. We show the results of tests performed to improve the performance of the pipeline and the convergence of the modal expansion. In addition, we present the measured bispectrum from a set of simulations with Gaussian initial condition, where the small amount of modes needed to accurately reconstruct the matter bispectrum shows the power of the modal expansion. The effective $f_{NL}$ value, corresponding to the bispectrum of the non-linear gravitational evolution, comes at no computational cost. In order to further test the pipeline, we proceed to measure the bispectrum of a few realisations with non-Gaussian initial conditions of the local type. We show that the modal decomposition can accurately separate the primordial signal, from the late-time non-Gaussianity, and put tight constraints on its amplitude.
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Scussel, Oscar. "On the use of Volterra series in structural dynamics : contributions from input-output to output-only analysis and identification /." Ilha Solteira, 2017. http://hdl.handle.net/11449/150506.
Повний текст джерелаАнотація:
Orientador: Samuel da SilvaResumo: Muitas aplicações da engenharia envolvem estruturas essencialmente não-lineares onde várias técnicas têm sido recentemente estudadas e investigadas por muitos pesquisadores. Dentre as várias abordagems, as que usam séries de Volterra têm apresentado propriedades úteis para fornecer um melhor entendimento para identificação e análise. Neste contexto, a presente tese propõem novas contribuições em como usar as séries de Volterra para caracterização, identificação e análise dinâmica de sistemas não-lineares usando sinais de entrada e saída e sinais somente de saída. Inicialmente, apresenta-se uma metodologia para análise de sistemas mecânicos não-lineares através das funções de resposta em frequência de alta-ordem (HOFRFs) e o conceito de HOFRFs estendidas com dados apenas de saída é introduzido e descrito em detalhes. Após isso, uma abordagem para identificação de sistemas não-lineares com base nas séries de Volterra através da expansão na base ortonormal de Kautz é proposta. Essa técnica permite identificar os seus núcleos mais facilmente e permite separar as contribuições dos termos lineares e não-lineares usando somente sinais de saída. Além disso, uma metodologia para análise modal de sistemas fracamente não-lineares sujeito a excitações com vários níveis de amplitude é também apresentada. A contribuição desse novo método reside no fato de que as HOFRFs são simplesmente estimadas como função das FRFs lineares. Basicamente, essa metodologia estende o conceito ... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Most recent engineering applications involve structures essentially nonlinear where several techniques have been recently studied and investigated by many researchers. Among them, the methods based on Volterra series expansion have presented powerful properties to provide a better understanding for identification and analysis. In this context, the present thesis proposes new contributions in how to use Volterra series for characterization, identification and dynamical analysis of nonlinear systems based on input and output signals and output-only signals. Initially, a methodology for analysis of nonlinear mechanical systems through higher-order frequency response functions (HOFRFs) is presented and the concept of extended HOFRFs based on output-only is introduced and described in detail. Afterwards, an approach for identification of nonlinear systems based on Volterra series through the expansion onto orthonormal Kautz basis is proposed. This technique allows to identify the Volterra kernels easily and enable to split the contribution of the linear and nonlinear terms using input-output as well as output-only signals. Furthermore, a methodology for modal analysis of weakly nonlinear systems under multilevel excitation is also proposed. The contribution of this new approach lies in the fact that HOFRFs are simply computed as functions of the linear FRFs. Basically, it extends the conventional experimental modal analysis methods in order to characterize and treat no... (Complete abstract click electronic access below)
Doutor
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Scussel, Oscar [UNESP]. "On the use of Volterra series in structural dynamics: contributions from input-output to output-only analysis and identification." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/150506.
Повний текст джерелаАнотація:
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Muitas aplicações da engenharia envolvem estruturas essencialmente não-lineares onde várias técnicas têm sido recentemente estudadas e investigadas por muitos pesquisadores. Dentre as várias abordagems, as que usam séries de Volterra têm apresentado propriedades úteis para fornecer um melhor entendimento para identificação e análise. Neste contexto, a presente tese propõem novas contribuições em como usar as séries de Volterra para caracterização, identificação e análise dinâmica de sistemas não-lineares usando sinais de entrada e saída e sinais somente de saída. Inicialmente, apresenta-se uma metodologia para análise de sistemas mecânicos não-lineares através das funções de resposta em frequência de alta-ordem (HOFRFs) e o conceito de HOFRFs estendidas com dados apenas de saída é introduzido e descrito em detalhes. Após isso, uma abordagem para identificação de sistemas não-lineares com base nas séries de Volterra através da expansão na base ortonormal de Kautz é proposta. Essa técnica permite identificar os seus núcleos mais facilmente e permite separar as contribuições dos termos lineares e não-lineares usando somente sinais de saída. Além disso, uma metodologia para análise modal de sistemas fracamente não-lineares sujeito a excitações com vários níveis de amplitude é também apresentada. A contribuição desse novo método reside no fato de que as HOFRFs são simplesmente estimadas como função das FRFs lineares. Basicamente, essa metodologia estende o conceito de métodos convencionais de analise modal experimental para caracterizar e tratar efeitos não-lineares. Os resultados via exemplos numéricos e experimentais apresentados ao longo da tese mostram as contribuições, benefícios e eficácia da proposta.
Most recent engineering applications involve structures essentially nonlinear where several techniques have been recently studied and investigated by many researchers. Among them, the methods based on Volterra series expansion have presented powerful properties to provide a better understanding for identification and analysis. In this context, the present thesis proposes new contributions in how to use Volterra series for characterization, identification and dynamical analysis of nonlinear systems based on input and output signals and output-only signals. Initially, a methodology for analysis of nonlinear mechanical systems through higher-order frequency response functions (HOFRFs) is presented and the concept of extended HOFRFs based on output-only is introduced and described in detail. Afterwards, an approach for identification of nonlinear systems based on Volterra series through the expansion onto orthonormal Kautz basis is proposed. This technique allows to identify the Volterra kernels easily and enable to split the contribution of the linear and nonlinear terms using input-output as well as output-only signals. Furthermore, a methodology for modal analysis of weakly nonlinear systems under multilevel excitation is also proposed. The contribution of this new approach lies in the fact that HOFRFs are simply computed as functions of the linear FRFs. Basically, it extends the conventional experimental modal analysis methods in order to characterize and treat nonlinear effects. The results based on numerical and experimental examples presented along the thesis show the contributions, benefits and effectiveness of the proposal.
FAPESP: 2012/09135-3
CNPq: 47058/2012-0
CNPq: 203610/2014-8
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Gazzo, Salvatore. "Characterisation of the mechanical behaviour of networks and woven fabrics with a discrete homogenization model." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSET006/document.
Повний текст джерелаАнотація:
Au cours des dernières décennies, le développement de nouveaux matériaux a progressé pour les applications liées à la mécanique. De nouvelles générations de composites ont été développées, qui peut offrir des avantages par rapport aux tapis unidirectionnels renforcés de fibres couramment utilisés les matériaux prennent alors le nom de woven fabrics. Le comportement de ce matériau est fortement influencé par la micro-structure du matériau. Dans la thèse, les modèles mécaniques et les schémas numériques capables de modéliser les comportement des tissus et des matériaux de réseau généraux ont été développés. Le modèle prend en compte la micro-structure au moyen d'une technique d'homogénéisation. Les fibres dans le réseau ont été traités comme des micro-poutres, ayant une rigidité à la fois en extension et en flexion, avec différents types de connexions. La procédure développée a été appliquée pour obtenir les modèles mécaniques homogénéisés pour certains types de réseaux de fibres biaxiaux et quadriaxiaux, simulant soit des réseaux de fibres (en ce cas a été supposé parmi les fibres) ou des tissus avec une interaction négligeable entre les faisceaux de fibres et en empêchant tout glissement relatif (dans ce cas, les connexions ont été simulés au moyen de pivots). Différentes géométries ont été analysées, y compris la cas dans lesquels les fibres ne sont pas orthogonales. On obtient généralement un premier milieu à gradient mais, dans certains cas, la procédure d'homogénéisation lui-même indique qu'un continuum d'ordre supérieur est mieux adapté pour représenter la déformation de la micro-structure. Des résultats spéciaux ont été obtenus dans le cas de fibres reliées par pivots. Dans ce cas, un matériau orthotrope à module de cisaillement nul a été obtenu. Un tel matériau a un tenseur constitutif elliptique, il peut donc conduire à des concentrations de contrainte. Cependant, il a été montré que certaines considérations sur le comportement physique de tels réseaux indiqué que les termes d'ordre supérieur inclus dans l'expansion des forces internes et des déformations, de sorte qu'un matériau de gradient de déformation a été obtenu. Les résultats obtenus peuvent être utilisés pour la conception de matériaux spécifiques nécessitant des propriétés. Bien que le modèle de référence soit un matériau de réseau, les résultats obtenus peuvent être appliqué à d'autres types similaires de microstructures, comme des matériaux pantographiques, des micro-dispositifs composé de micro-poutres, etc. Ils étaient limités à la gamme d'élasticité linéaire, qui est petite déformation et comportement élastique linéaire. Ensuite, les simulations numériques ont été axées sur les tests d'extension et les tests de biais. Le obtenu configurations déformées sont conformes aux tests expérimentaux de la littérature, tant pour tissus équilibrés et non équilibrés. De plus, une comparaison entre les premier et deuxième gradients des prédictions numériques ont été effectuées. Il a été observé que les prédictions de deuxième gradient mieux simuler les preuves expérimentalesIn the past decades there has been an impressive progress in the development of new materials for mechanical related applications. New generations of composites have been developed, that can offer advantages over the unidirectional fibre-reinforced mats commonly used then materials take the name of woven fabrics. The behaviour of this material is strongly influenced by the micro-structure of the material. In the thesis mechanical models and a numerical scheme able to model the mechanical behaviour of woven fabrics and general network materials have been developed. The model takes in to account the micro-structure by means of a homogenization technique. The fibres in the network have been treated like microbeams, having both extensional and bending stiffness, with different types of connection, according to the pattern and detail of the network. The developed procedure was applied for obtaining the homogenized mechanical models for some types of biaxial and quadriaxial networks of fibres, simulating either fibre nets (in this case rigid connection were assumed among the fibres) or tissues with negligible interaction between the fibre bundles, and with relative sliding prevented (in this case the connections were simulated by means of pivots). Different geometries were analysed, including the cases in which the fibres are not orthogonal. A first gradient medium is usually obtained but, in some cases, the homogenization procedure itself indicates that a higher order continuum is better fit to represent the deformation of the micro-structure. Special results were obtained for the case of fibres connected by pivots. In this cases an orthotropic material with zero shear modulus was obtained. Such a material has a not elliptic constitutive tensor, thus it can lead to strain concentrations. However, it was shown that some considerations about the physical behaviour of such networks indicated that higher order terms had to be included in the expansion of the internal forces and deformations, so that a strain gradient material was obtained. The results obtained can be used for the design of specific materials requiring ad-hoc properties. Although the reference model is a network material, the results obtained can be applied to other similar kinds of microstructures, like pantographic materials, micro devices composed by microbeams etc. They have been limited at the range of linear elasticity, that is small deformation and linear elastic behaviour. Then, numerical simulations were focused on extension tests and bias tests. The obtained deformed configurations are consistent with the literature experimental tests, both for balanced and unbalanced tissues. Moreover, a comparison between first and second gradient numerical predictions was performed. It was observed that second gradient predictions better simulate the experimental evidences
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Yu, Hao-wei, and 俞皓維. "Model Competition of Higher-order Spatial Factor Structures with Comparisons between Parameter Estimation Methods." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/fzcc2t.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
數位學習與教育研究所
99
The purpose of the study is to find the best and the most parsimonius explanatory model for the standardized spatial ability test (SPAT) through higher-order confirmatory factor analysis and model competition, because based on SPAT’s development and construction algorithm, there are seven possible structure models underlie SPAT, including first-, second-, and third-order models. The data used is SPAT’s norm sample, which are 1,641 first-year senior high school students. There are 18 test items categorized into four item types and two spatial factors. In parameter estimation, maximum likelihood estimation (ML) and diagonally weighted least squares (DWLS) are both applied to compare their differential impact. Results show that the number of models fitted well by DWLS is more than those by ML. The choice of the best and parsimonious model by both estimation methods is the same second-order structure of which, the first order being the four item types, and the second order being the test construct - spatial ability. It is confirmed that SPAT is of higher-order structure. But besides the choice of the second-order structure, other higher-order structure models are not better than lower-order ones. The reason may be that there is limited number of spatial factors in SPAT, there is limited number of item types in the factors, and there is limited number of items in the item types. The choice of the second-order structure can be used in SPAT’s future application and explanation. If future edition and reconstruction is possible, it would be appropriate that the numbers of factors, item types, and items be increased to stabilize SPAT’s higher-order measurement structure.
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Park, Kyoungup. "A learning framework for higher-order consistency models in multi-class pixel labeling problems." Phd thesis, 2014. http://hdl.handle.net/1885/12686.
Повний текст джерелаАнотація:
Recently, higher-order Markov random field (MRF) models have been successfully
applied to problems in computer vision, especially scene understanding problems.
One successful higher-order MRF model for scene understanding is the consistency
model [Kohli and Kumar, 2010; Kohli et al., 2009] and earlier work by Ladicky et al.
[2009, 2013] which contain higher-order potentials composed of lower linear envelope
functions. In semantic image segmentation problems, which seek to identify the pixels of images with pre-defined labels of objects and backgrounds, this model encourages consistent label assignments over segmented regions of images. However, solving this MRF problem exactly is generally NP-hard; instead, efficient approximate inference algorithms are used. Furthermore, the lower linear envelope functions involve a number of parameters to learn. But, the typical cross-validation used for pairwise MRF models is not a practical method for estimating such a large number of parameters. Nevertheless, few works have proposed efficient learning methods to deal with the large number of parameters in these consistency models. In this thesis, we propose a unified inference and learning framework for the consistency model. We investigate various issues and present solutions for inference and learning with this higher-order MRF model as follows. First, we derive two variants of the consistency model for multi-class pixel labeling tasks. Our model defines an energy function scoring any given label assignments over an image. In order to perform Maximum a posteriori (MAP) inference in this model, we minimize the energy function using move-making algorithms in which the higher-order problems are transformed into tractable pairwise problems. Then, we employ a max-margin framework for learning optimal parameters. This learning framework provides a generalized approach for searching the large parameter space. Second, we propose a novel use of the Gaussian mixture model (GMM) for encoding consistency constraints over a large set of pixels. Here, we use various oversegmentation methods to define coherent regions for the consistency potentials. In general, Mean shift (MS) produces locally coherent regions, and GMM provides globally coherent regions, which do not need to be contiguous. Our model exploits both local and global information together and improves the labeling accuracy on real data sets. Accordingly, we use multiple higher-order terms associated with each over-segmentation method. Our learning framework allows us to deal with the large
number of parameters involved with multiple higher-order terms. Next, we explore a dual decomposition (DD) method for our multi-class consistency model. The dual decomposition MRF (DD-MRF) is an alternative method for optimizing the energy function. In dual decomposition, a complex MRF problem is decomposed into many easy subproblems and we optimize the relaxed dual problem
using a projected subgradient method. At convergence, we expect a global optimum
in the dual space because it is a concave maximization problem. To optimize our
higher-order DD-MRF exactly, we propose an exact minimization algorithm for solving
the higher-order subproblems. Moreover, the minimization algorithm is much more efficient than graph-cuts. The dual decomposition approach also solves the
max-margin learning problem by minimizing the dual losses derived from DD-MRF.
Here, our minimization algorithm allows us to optimize the DD learning exactly and
efficiently, which in most cases finds better parameters than the previous learning
approach. Last, we focus on improving labeling accuracies of our higher-order model by combining mid-level features, which we call region features. The region features
help customize the general envelope functions for individual segmented regions.
By assigning specified weights to the envelope functions, we can choose subsets of
highly likely labels for each segmented region. We train multiple classifiers with
region features and aggregate them to increase prediction performance of possible
labels for each region. Importantly, introducing these region features does not change the previous inference and learning algorithms.
Книги з теми "Higher-order structural model"
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Kantartzis, Nikolaos V. Higher order FDTD schemes for waveguide and antenna structures. [San Rafael, Calif.]: Morgan and Claypool, 2006.
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Koldaev, Viktor. Theoretical and methodological aspects of the use of information technologies in education. ru: INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1014651.
Повний текст джерелаАнотація:
The article summarizes the experience of implementing a personality-oriented approach to the formation of a structural and content model of the educational process at the university. The results of the introduction of information technologies and their services in the field of education are presented, as well as the impact of computerization on the quality of education in the framework of the modern educational paradigm. The priority directions of innovative educational strategies of the university are identified and a graph model of the individual educational route of the student is proposed in order to predict the state of the educational system and adopt optimal learning strategies. Meets the requirements of the federal state educational standards of higher education of the latest generation. For graduate students and university teachers in the design of variable models of training in any areas of training and specialties. It will be useful for advanced training on the problems of innovative educational strategies.
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United States. National Aeronautics and Space Administration., ed. A new higher-order composite theory for analysis and design of high speed tilt-rotor blades. [Washington, D.C.]: National Aeronautics and Space Administration, 1996.
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United States. National Aeronautics and Space Administration., ed. A new higher-order composite theory for analysis and design of high speed tilt-rotor blades. [Washington, D.C.]: National Aeronautics and Space Administration, 1996.
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Bornkessel-Schlesewsky, Ina, and Petra B. Schumacher. Towards a Neurobiology of Information Structure. Edited by Caroline Féry and Shinichiro Ishihara. Oxford University Press, 2016. http://dx.doi.org/10.1093/oxfordhb/9780199642670.013.22.
Повний текст джерелаАнотація:
This chapter reviews neurophysiological and neuroanatomical investigations of information structural notions, with a view to working towards a neurobiologically grounded perspective. It first considers components of a neurobiologically plausible theory of information structure and outlines candidate mechanisms for higher-order cognitive processing, namely prediction and mental modelling, attention orientation, memory, and inferencing. The chapter then proceeds to neuroscientific investigations of information structure, highlighting differences between sentence- and text-level processing and discussing findings for the information structural notions of givenness, focus, and topic, before presenting further insights from syntax-induced information structural effects. The chapter concludes with a discussion of neurobiological models of information structure processing.
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Tsiboukis, Theodoros D., and Nikolaos V. Kantartzis. Higher-order FDTD Schemes for Waveguides and Antenna Structures (Synthesis Lectures on Computational Electromagnetics). Morgan & Claypool Publishers, 2007.
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A new higher-order composite theory for analysis and design of high speed tilt-rotor blades. [Washington, D.C.]: National Aeronautics and Space Administration, 1996.
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A new higher-order composite theory for analysis and design of high speed tilt-rotor blades. [Washington, D.C.]: National Aeronautics and Space Administration, 1996.
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Allik, Jüri, and Anu Realo. Universal and Specific in the Five Factor Model of Personality. Edited by Thomas A. Widiger. Oxford University Press, 2015. http://dx.doi.org/10.1093/oxfordhb/9780199352487.013.23.
Повний текст джерелаАнотація:
Personality psychologists—perhaps even more than in some other disciplines—are deeply interested in what is common to personality descriptions in all cultures and societies. The purpose of this chapter is to discuss the potential universality of the Five Factor Model (FFM) of general personality structure. The chapter begins with a discussion of what is meant, or should be meant, by a universal. Discussed then is the empirical support, as well as the conceptual and empirical difficulty, in establishing universality in personality structure, for the FFM as well as other dimensional models. The chapter then considers different levels of analysis (including cultural and intraindividual analyses), higher-order invariants (including sex differences, age differences, and differences in perspective), and whether mean levels are universal. The chapter concludes with a discussion of the basis for personality universals, as well as addressing the common challenges to universality.
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Maloney, J. Christopher. What It Is Like To Perceive. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780190854751.001.0001.
Повний текст джерелаАнотація:
Conscious perception is a distinctive mode of cognition marked by its manifestly sensuous phenomenal character. Why? An intentionalist may reply that perception is a kind of psychological state realized by an oddly contentful mental representation. A higher order theorist might alternatively answer that a perceptual state is sensuous since it is the content of a higher order cognitive state. Neither of these representationalists is right. It is not the content of any mental state that ensures perception's phenomenal character. Rather, the unique structure of a perceptual representation determines perception's sensuous side. For a perceptual representation is an extended mental representation of a peculiar sort. It is a representation in which the vehicle of reference is itself the very object to which that vehicle refers. Perceptual representation thus differs from all other forms of cognitive representation in a way that directly acquaints a perceiver with whatever real object she perceives. Perception is sensuous because it is unbrokered cognitive contact with something present. This confrontational mode of cognition owes its phenomenal character not to what it represents but rather to how it represents. What it is like to perceive is bluntly - but exactly - to represent something real that is really at hand. Conscious perception is just direct acquaintance with what's there.
Частини книг з теми "Higher-order structural model"
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Xie, Fengjie, Mengdi Ma, and Panpan Yang. "Study on the Construction and Structural Characteristics of the Higher-Order High-Speed Railway Network Model." In Advances in Natural Computation, Fuzzy Systems and Knowledge Discovery, 1221–33. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70665-4_132.
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Doyle, James F. "Higher Order Waveguide Models." In Wave Propagation in Structures, 123–83. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-59679-8_5.
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Chelidze, David. "Higher-Order Decompositions for Modal Identification and Model Order Reduction." In Nonlinear Structures & Systems, Volume 1, 271–78. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-47626-7_39.
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Li, Fucai, Lin Ye, Gui Cai Zhang, and Guang Meng. "Bearing Fault Detection Using Higher-Order Statistics Based ARMA Model." In Damage Assessment of Structures VII, 271–76. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/0-87849-444-8.271.
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Ratajczak, Martin, Sebastian Tschiatschek, and Franz Pernkopf. "Structured Regularizer for Neural Higher-Order Sequence Models." In Machine Learning and Knowledge Discovery in Databases, 168–83. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-23528-8_11.
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Andrianov, Igor V., Vladyslav V. Danishevskyy, Julius D. Kaplunov, and Bernd Markert. "Wide Frequency Higher-Order Dynamic Model for Transient Waves in a Lattice." In Advanced Structured Materials, 3–12. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-92234-8_1.
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Fonseca, Irene. "Bending moment and higher order membrane models-lecture IV." In Classical and Advanced Theories of Thin Structures, 219–33. Vienna: Springer Vienna, 2008. http://dx.doi.org/10.1007/978-3-211-85430-3_8.
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Dixon, Alex, Ranko Lazić, Andrzej S. Murawski, and Igor Walukiewicz. "Leafy automata for higher-order concurrency." In Lecture Notes in Computer Science, 184–204. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-71995-1_10.
Повний текст джерелаАнотація:
AbstractFinitary Idealized Concurrent Algol ($$\mathsf {FICA}$$ FICA ) is a prototypical programming language combining functional, imperative, and concurrent computation. There exists a fully abstract game model of $$\mathsf {FICA}$$ FICA , which in principle can be used to prove equivalence and safety of $$\mathsf {FICA}$$ FICA programs. Unfortunately, the problems are undecidable for the whole language, and only very rudimentary decidable sub-languages are known.We propose leafy automata as a dedicated automata-theoretic formalism for representing the game semantics of $$\mathsf {FICA}$$ FICA . The automata use an infinite alphabet with a tree structure. We show that the game semantics of any $$\mathsf {FICA}$$ FICA term can be represented by traces of a leafy automaton. Conversely, the traces of any leafy automaton can be represented by a $$\mathsf {FICA}$$ FICA term. Because of the close match with $$\mathsf {FICA}$$ FICA , we view leafy automata as a promising starting point for finding decidable subclasses of the language and, more generally, to provide a new perspective on models of higher-order concurrent computation.Moreover, we identify a fragment of $$\mathsf {FICA}$$ FICA that is amenable to verification by translation into a particular class of leafy automata. Using a locality property of the latter class, where communication between levels is restricted and every other level is bounded, we show that their emptiness problem is decidable by reduction to Petri net reachability.
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Broadbent, Christopher, and Luke Ong. "On Global Model Checking Trees Generated by Higher-Order Recursion Schemes." In Foundations of Software Science and Computational Structures, 107–21. Berlin, Heidelberg: Springer Berlin Heidelberg, 2009. http://dx.doi.org/10.1007/978-3-642-00596-1_9.
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Verhoosel, Clemens V., Michael A. Scott, Michael J. Borden, Thomas J. R. Hughes, and René de Borst. "Discretization of Higher Order Gradient Damage Models Using Isogeometric Finite Elements." In Damage Mechanics of Cementitious Materials and Structures, 89–120. Hoboken, NJ USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118562086.ch4.
Повний текст джерелаТези доповідей конференцій з теми "Higher-order structural model"
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Buannic, Natacha, and Patrice Cartraud. "Higher-order asymptotic model for a heterogeneous beam, including corrections due to end effects." In 41st Structures, Structural Dynamics, and Materials Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2000. http://dx.doi.org/10.2514/6.2000-1495.
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Lo, S. H., Wu Zhen, and Siu-Lai Chan. "Thermal stress analysis of laminated plates using global-local higher-order model." In International Conference on Performance-based and Life-cycle Structural Engineering. School of Civil Engineering, The University of Queensland, 2015. http://dx.doi.org/10.14264/uql.2016.1097.
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Gozen, Serif, Brian J. Olson, Steven W. Shaw, and Christophe Pierre. "Resonance Suppression in Multi-DOF Rotating Flexible Structures Using Order-Tuned Absorbers." In ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/detc2009-86287.
Повний текст джерелаАнотація:
This paper considers the dynamic response and order-tuning of vibration absorbers fitted to a rotating flexible structure under traveling wave (TW) engine order excitation. Of specific interest is the extension of previous results on the so-called no-resonance zone, that is, a region in linear tuning parameter space in which the coupled structure/absorber system does not experience resonance over all rotation speeds. The no-resonance feature was shown to exist for cyclic rotating structures with one structural and one absorber degree-of-freedom (DOF) per sector. This work uses a higher-fidelity structural model to investigate the effects of higher modes on the cyclically-coupled system. It is shown that the no-resonance zone is replaced by a resonance-suppression zone in which one structural mode is suppressed, but higher-order resonances still exist with the addition of the absorbers. The results are general, in the sense that one vibration mode can be eliminated using a set of identically-tuned absorbers on a rotating structure with arbitrarily many DOFs per sector.
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NAGARAJ, MANISH H., ERASMO CARRERA, and MARCO PETROLO. "GLOBAL-LOCAL PROGRESSIVE DAMAGE ANALYSIS OF COMPOSITE LAMINATES USING LAYER-WISE HIGHER-ORDER STRUCTURAL MODELSv." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35887.
Повний текст джерелаАнотація:
The objective of the current work is to develop a global-local framework for the progressive damage analysis of composite laminated structures. The technique involves two sequential analyses—an initial low-fidelity 3D-FE based linear analysis of the global structure, followed by the local nonlinear analysis of critical regions where damage is likely to occur. The numerical models used for the local analysis are developed using higher-order layer-wise structural theories obtained via the Carrera Unified Formulation. Composite damage is modelled using the CODAM2 model based on continuum damage mechanics, and the nonlinear problem is solved using explicit time integration schemes. Preliminary assessments are carried out to validate the proposed global-local framework by considering open-hole tensile specimens of quasi-isotropic composite laminates. Both full-scale CUF models and the proposed global-local approach are used to predict the tensile strength of the specimen. It is shown that the obtained results are in good agreement with experiment data, thus validating the framework, and a multi-fold improvement in computational time is demonstrated.
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Chandiramani, N. K., L. I. Librescu, and C. D. Shete. "Free-Vibration of Rotating Composite Beams Incorporating Higher-Order Transverse Shear Effects." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/pvp-25204.
Повний текст джерелаАнотація:
Abstract The free vibration behavior of a rotating blade modeled as a laminated composite hollow (single celled) box beam is studied. The geometrically nonlinear structural model developed herein incorporates a number of non-classical effects such as anisotropy, heterogeneity, transverse shear flexibility, and warping inhibition. The centrifugal and Coriolis force field effects are also included. The main focus here being the refinement of the existing model, the traction-free boundary conditions are satisfied here in contrast to the existing model. The resulting linearized equations and numerical results based on them are presented. Results obtained for the present higher-order shearable model are compared with those of the existing first-order shearable and the non-shearable models. Tailoring studies using the present model reveal an enhancement of eigenfrequency characteristics.
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Thompson, Thomas J. "Spherical Compliant Model for Vibration Estimation and Control." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0577.
Повний текст джерелаАнотація:
Abstract Proposed space missions involve large structures which must maintain precise dimensional tolerances during dynamic maneuvers. In order to attenuate disturbances in the many modes of vibration of such structures, active and passive vibration control has been proposed. Passive control is to be achieved by placing viscous or viscoelastic members in a structure to absorb energy, while active control similarly could involve structural members (struts) capable of sensing axial displacement and exerting axial control force. With conventional modal analysis, the effect of a control element on a system is computed by summing its influence on many immutable modes. Since changes in mode shape must be described by this summation, truncation of higher modes results in inaccuracies. The compliant model of vibration to be presented accurately accounts for the effects of locally-acting control elements without inclusion of high-frequency modes. The motion of each spring-mass system representing a structural mode is modified by a control element in series with another stiffness inherent to the structure for that mode and control position. In order to predict the influence of several control elements or dampers on closely-spaced modes, the compliant models for those modes are integrated into a spherical model in which one lumped mass is acted upon by orthogonal modal stiffnesses. In the spherical model, control elements influent the lumped mass from orientations determined by mode participation factors. The resulting equations of motion are stated in standard state-space form. To test accuracy, the compliant model is used to predict eigenvalue shifts due to springs and dampers acting upon an axially-vibrating rod, and the spherical model is used to predict damping accurately in a lumped-mass system with closely-spaced modes.
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Rao, B. N., and Rajib Chowdhury. "Structural Reliability Evaluation Using Enhanced HDMR." In ASME 2008 Pressure Vessels and Piping Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/pvp2008-61876.
Повний текст джерелаАнотація:
This paper presents a new computational tool for predicting failure probability of randomly parametered structural/mechanical systems based on high dimensional model representation (HDMR) generated from low order function components. HDMR is a general set of quantitative model assessment and analysis tools for capturing the high-dimensional relationships between sets of input and output model variables. When first-order HDMR approximation of the original high dimensional implicit limit state/performance function is not adequate to provide desired accuracy to the predicted failure probability, this paper presents an enhanced HDMR (eHDMR) method to represent the higher order terms of HDMR expansion by expressions similar to the lower order ones with monomial multipliers. The accuracy of the HDMR expansion can be significantly improved using preconditioning with a minimal number of additional input-output samples without directly invoking the determination of second- and higher order HDMR terms. This study aims to assess how accurately and efficiently eHDMR approximation technique can capture complex model output uncertainty. As a part of this effort, the efficacy of HDMR approximation, which is recently applied to reliability analysis, is also demonstrated. Once the approximate form of implicit response function is defined using HDMR/eHDMR, the failure probability can be obtained by statistical simulation.
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Oh, Jinho, Jinbok Choi, and Jeong-Soo Ryu. "A Response Spectrum Approach Using Model Order Reduction for Seismic Analysis." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97225.
Повний текст джерелаАнотація:
A response spectrum analysis (RSA) has been widely known as one of the methods used for the purpose of an earthquake-resistant design of a structure in the nuclear industry through evaluating the structural integrity during and after seismic events. Recently, as the structures, systems, and components for the design are massive, complex, and complicate, a considerable amount of computational resources and time is required for applying the RSA. Reduced methods have been considered as important technique to resolve computational resources and time problem. For a few decades, various approximate techniques have been developed to obtain the dynamic characteristic in a reduced manner. This paper adopts the model order reduction (MOR) technique known as the one of various reduction methods. The MOR for solving the large linear system in mathematics has been studied by a number of researchers. The MOR is achieved by applying a projection from a higher-order to a lower-order space using Krylov subspaces generated by the Arnoldi algorithm. It has been extended to engineering applications such as circuit analysis, structural analysis, and multi-scale analysis. However, it has not yet been applied in RSA. The aim of this study is to evaluate applicability of the MOR into RSA. Numerical examples demonstrate that the proposed method saves computational costs effectively with maintaining accuracy. Thus, it is confirmed that the proposed method is valid and applicable in predicting seismic responses.
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"Vibration-Based Detection of Loosened Bolts on Pipes Attached to Bridges." In Structural Health Monitoring. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901311-28.
Повний текст джерелаАнотація:
Abstract. U-bolts are critical points of maintenance in pipeline facilities supported by girders of bridges. However, it is difficult to detect loosened U-bolts by visual inspection. To avoid this problem, we have developed a vibration-based method to detect loosening of bolts based on measurements of actual equipment. First, the vibration of a communication pipeline attached to a road bridge was measured when vehicles passed over it. During the measurements, the U-bolts were set in tightened and loosened states. We found that the frequency changes between the tightened and loosened states was too small for practical use. On the other hand, a strong spectrum in the high frequency region (above 80 Hz) appeared only in the tightened state. Next, a model facility was built to simulate a communication pipeline attached to bridge. A hammering test and modal and frequency response analyses were performed by using the finite element method (FEM). The results suggested that high frequency peaks appearing only in the tightened U-bolt are due to the higher rate of force transfer of the natural frequency from the platform. In addition, the pipe is strongly fixed when the U-bolt is tightened, which may lead to stronger high order modes that cause complex deformation of the pipe. The conventional method is to detect loosening of bolts from changes in the natural frequency. However, in actual equipment, confirming the absence of a high-frequency spectrum is more suitable for detecting loosened bolts.
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Chattopadhyay, Aditi, and Dan Dragomir-Daescu. "Damage Modeling and Detection in Smart Composites." In ASME 2000 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/imece2000-2160.
Повний текст джерелаАнотація:
Abstract The presence of damage in structures made out of composite and/or piezoelectric materials can cause significant degradation in structural performance. In the present paper, damage indices based on two-dimensional gapped smoothing technique and model strains are developed in order to enhance the accuracy in predicting the location and extent of damage in composite structures. Structural analysis is performed based on a refined higher order theory, which can capture the transverse shear effects in anisotropic laminates. An approach using the developed damage indices and the laminate model of the higher order theory is employed to model and identify delaminations in composite laminates. It is also used in the delamination analysis of composite laminates with piezoelectric actuators. The proposed modal strain based damage indexes are used to perform delamination analysis. Comparison study is performed to illustrate that the reliability and robustness of the new proposed damage indices in locating delaminations in composite and smart composite structures. The effects on modal strain and damage indices due to the presence of surface bounded piezoelectric actuators are also presented and discussed.
Звіти організацій з теми "Higher-order structural model"
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Riveros, Guillermo, Felipe Acosta, Reena Patel, and Wayne Hodo. Computational mechanics of the paddlefish rostrum. Engineer Research and Development Center (U.S.), September 2021. http://dx.doi.org/10.21079/11681/41860.
Повний текст джерелаАнотація:
Purpose – The rostrum of a paddlefish provides hydrodynamic stability during feeding process in addition to detect the food using receptors that are randomly distributed in the rostrum. The exterior tissue of the rostrum covers the cartilage that surrounds the bones forming interlocking star shaped bones. Design/methodology/approach – The aim of this work is to assess the mechanical behavior of four finite element models varying the type of formulation as follows: linear-reduced integration, linear-full integration, quadratic-reduced integration and quadratic-full integration. Also presented is the load transfer mechanisms of the bone structure of the rostrum. Findings – Conclusions are based on comparison among the four models. There is no significant difference between integration orders for similar type of elements. Quadratic-reduced integration formulation resulted in lower structural stiffness compared with linear formulation as seen by higher displacements and stresses than using linearly formulated elements. It is concluded that second-order elements with reduced integration and can model accurately stress concentrations and distributions without over stiffening their general response. Originality/value – The use of advanced computational mechanics techniques to analyze the complex geometry and components of the paddlefish rostrum provides a viable avenue to gain fundamental understanding of the proper finite element formulation needed to successfully obtain the system behavior and hot spot locations.
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Yu, D. Damping of Higher-Order Modes in a Threefold Symmetry Accelerating Structure. Office of Scientific and Technical Information (OSTI), April 2005. http://dx.doi.org/10.2172/839841.
Повний текст джерела
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Simakov, Evgenya I., Sergey Arsenyev, William B. Haynes, Sergey S. Kurennoy, Michael Madrid, James F. O'Hara, Eric R. Olivas, et al. Employing photonic band gap cavities for filtering higher order modes in SRF accelerator structures. Office of Scientific and Technical Information (OSTI), November 2012. http://dx.doi.org/10.2172/1054674.
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Baboi, Nicoleta. IMPEDANCE MEASUREMENT SETUP FOR HIGHER-ORDER MODE STUDIES IN NLC ACCELERATING STRUCTURES WITH THE WIRE METHOD. Office of Scientific and Technical Information (OSTI), September 2002. http://dx.doi.org/10.2172/801788.
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VanderGheynst, Jean, Michael Raviv, Jim Stapleton, and Dror Minz. Effect of Combined Solarization and in Solum Compost Decomposition on Soil Health. United States Department of Agriculture, October 2013. http://dx.doi.org/10.32747/2013.7594388.bard.
Повний текст джерелаАнотація:
In soil solarization, moist soil is covered with a transparent plastic film, resulting in passive solar heating which inactivates soil-borne pathogen/weed propagules. Although solarization is an effective alternative to soil fumigation and chemical pesticide application, it is not widely used due to its long duration, which coincides with the growing season of some crops, thereby causing a loss of income. The basis of this project was that solarization of amended soil would be utilized more widely if growers could adopt the practice without losing production. In this research we examined three factors expected to contribute to greater utilization of solarization: 1) investigation of techniques that increase soil temperature, thereby reducing the time required for solarization; 2) development and validation of predictive soil heating models to enable informed decisions regarding soil and solarization management that accommodate the crop production cycle, and 3) elucidation of the contributions of microbial activity and microbial community structure to soil heating during solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays, and samples were subjected to 16S ribosomal RNA gene sequencing to characterize microbial communities. Amendment of soil with 10% (g/g) compost containing 16.9 mg CO2/g dry weight organic carbon resulted in soil temperatures that were 2oC to 4oC higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization. The sequencing data obtained from field samples revealed similar microbial species richness and evenness in both solarized amended and non-amended soil. However, amendment led to enrichment of a community different from that of non-amended soil after solarization. Moreover, community structure varied by soil depth in solarized soil. Coupled with temperature data from soil during solarization, community data highlighted how thermal gradients in soil influence community structure and indicated microorganisms that may contribute to increased soil heating during solarization. Reliable predictive tools are necessary to characterize the solarization process and to minimize the opportunity cost incurred by farmers due to growing season abbreviation, however, current models do not accurately predict temperatures for soils with internal heat generation associated with the microbial breakdown of the soil amendment. To address the need for a more robust model, a first-order source term was developed to model the internal heat source during amended soil solarization. This source term was then incorporated into an existing “soil only” model and validated against data collected from amended soil field trials. The expanded model outperformed both the existing stable-soil model and a constant source term model, predicting daily peak temperatures to within 0.1°C during the critical first week of solarization. Overall the results suggest that amendment of soil with compost prior to solarization may be of value in agricultural soil disinfestations operations, however additional work is needed to determine the effects of soil type and organic matter source on efficacy. Furthermore, models can be developed to predict soil temperature during solarization, however, additional work is needed to couple heat transfer models with pathogen and weed inactivation models to better estimate solarization duration necessary for disinfestation.
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Agassi, Menahem, Michael J. Singer, Eyal Ben-Dor, Naftaly Goldshleger, Donald Rundquist, Dan Blumberg, and Yoram Benyamini. Developing Remote Sensing Based-Techniques for the Evaluation of Soil Infiltration Rate and Surface Roughness. United States Department of Agriculture, November 2001. http://dx.doi.org/10.32747/2001.7586479.bard.
Повний текст джерелаАнотація:
The objective of this one-year project was to show whether a significant correlation can be established between the decreasing infiltration rate of the soil, during simulated rainstorm, and a following increase in the reflectance of the crusting soil. The project was supposed to be conducted under laboratory conditions, using at least three types of soils from each country. The general goal of this work was to develop a method for measuring the soil infiltration rate in-situ, solely from the reflectance readings, using a spectrometer. Loss of rain and irrigation water from cultivated fields is a matter of great concern, especially in arid, semi-arid regions, e.g. much of Israel and vast area in US, where water is a limiting factor for crop production. A major reason for runoff of rain and overhead irrigation water is the structural crust that is generated over a bare soils surface during rainfall or overhead irrigation events and reduces its infiltration rate (IR), considerably. IR data is essential for predicting the amount of percolating rainwater and runoff. Available information on in situ infiltration rate and crust strength is necessary for the farmers to consider: when it is necessary to cultivate for breaking the soil crust, crust strength and seedlings emergence, precision farming, etc. To date, soil IR is measured in the laboratory and in small-scale field plots, using rainfall simulators. This method is tedious and consumes considerable resources. Therefore, an available, non-destructive-in situ methods for soil IR and soil crusting levels evaluations, are essential for the verification of infiltration and runoff models and the evaluation of the amount of available water in the soil. In this research, soil samples from the US and Israel were subjected to simulated rainstorms of increasing levels of cumulative energies, during which IR (crusting levels) were measured. The soils from the US were studied simultaneously in the US and in Israel in order to compare the effect of the methodology on the results. The soil surface reflectance was remotely measured, using laboratory and portable spectrometers in the VIS-NIR and SWIR spectral region (0.4-2.5mm). A correlation coefficient spectra in which the wavelength, consisting of the higher correlation, was selected to hold the highest linear correlation between the spectroscopy and the infiltration rate. There does not appear to be a single wavelength that will be best for all soils. The results with the six soils in both countries indeed showed that there is a significant correlation between the infiltration rate of crusted soils and their reflectance values. Regarding the wavelength with the highest correlation for each soil, it is likely that either a combined analysis with more then one wavelength or several "best" wavelengths will be found that will provide useful data on soil surface condition and infiltration rate. The product of this work will serve as a model for predicting infiltration rate and crusting levels solely from the reflectance readings. Developing the aforementioned methodologies will allow increased utilization of rain and irrigation water, reduced runoff, floods and soil erosion hazards, reduced seedlings emergence problems and increased plants stand and yields.
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Hlushak, Oksana M., Svetlana O. Semenyaka, Volodymyr V. Proshkin, Stanislav V. Sapozhnykov, and Oksana S. Lytvyn. The usage of digital technologies in the university training of future bachelors (having been based on the data of mathematical subjects). [б. в.], July 2020. http://dx.doi.org/10.31812/123456789/3860.
Повний текст джерелаАнотація:
This article demonstrates that mathematics in the system of higher education has outgrown the status of the general education subject and should become an integral part of the professional training of future bachelors, including economists, on the basis of intersubject connection with special subjects. Such aspects as the importance of improving the scientific and methodological support of mathematical training of students by means of digital technologies are revealed. It is specified that in order to implement the task of qualified training of students learning econometrics and economic and mathematical modeling, it is necessary to use digital technologies in two directions: for the organization of electronic educational space and in the process of solving applied problems at the junction of the branches of economics and mathematics. The advantages of using e-learning courses in the educational process are presented (such as providing individualization of the educational process in accordance with the needs, characteristics and capabilities of students; improving the quality and efficiency of the educational process; ensuring systematic monitoring of the educational quality). The unified structures of “Econometrics”, “Economic and mathematical modeling” based on the Moodle platform are the following ones. The article presents the results of the pedagogical experiment on the attitude of students to the use of e-learning course (ELC) in the educational process of Borys Grinchenko Kyiv University and Alfred Nobel University (Dnipro city). We found that the following metrics need improvement: availability of time-appropriate mathematical materials; individual approach in training; students’ self-expression and the development of their creativity in the e-learning process. The following opportunities are brought to light the possibilities of digital technologies for the construction and research of econometric models (based on the problem of dependence of the level of the Ukrainian population employment). Various stages of building and testing of the econometric model are characterized: identification of variables, specification of the model, parameterization and verification of the statistical significance of the obtained results.
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Kirchhoff, Helmut, and Ziv Reich. Protection of the photosynthetic apparatus during desiccation in resurrection plants. United States Department of Agriculture, February 2014. http://dx.doi.org/10.32747/2014.7699861.bard.
Повний текст джерелаАнотація:
In this project, we studied the photosynthetic apparatus during dehydration and rehydration of the homoiochlorophyllous resurrection plant Craterostigmapumilum (retains most of the photosynthetic components during desiccation). Resurrection plants have the remarkable capability to withstand desiccation, being able to revive after prolonged severe water deficit in a few days upon rehydration. Homoiochlorophyllous resurrection plants are very efficient in protecting the photosynthetic machinery against damage by reactive oxygen production under drought. The main purpose of this BARD project was to unravel these largely unknown protection strategies for C. pumilum. In detail, the specific objectives were: (1) To determine the distribution and local organization of photosynthetic protein complexes and formation of inverted hexagonal phases within the thylakoid membranes at different dehydration/rehydration states. (2) To determine the 3D structure and characterize the geometry, topology, and mechanics of the thylakoid network at the different states. (3) Generation of molecular models for thylakoids at the different states and study the implications for diffusion within the thylakoid lumen. (4) Characterization of inter-system electron transport, quantum efficiencies, photosystem antenna sizes and distribution, NPQ, and photoinhibition at different hydration states. (5) Measuring the partition of photosynthetic reducing equivalents between the Calvin cycle, photorespiration, and the water-water cycle. At the beginning of the project, we decided to use C. pumilum instead of C. wilmsii because the former species was available from our collaborator Dr. Farrant. In addition to the original two dehydration states (40 relative water content=RWC and 5% RWC), we characterized a third state (15-20%) because some interesting changes occurs at this RWC. Furthermore, it was not possible to detect D1 protein levels by Western blot analysis because antibodies against other higher plants failed to detect D1 in C. pumilum. We developed growth conditions that allow reproducible generation of different dehydration and rehydration states for C. pumilum. Furthermore, advanced spectroscopy and microscopy for C. pumilum were established to obtain a detailed picture of structural and functional changes of the photosynthetic apparatus in different hydrated states. Main findings of our study are: 1. Anthocyan accumulation during desiccation alleviates the light pressure within the leaves (Fig. 1). 2. During desiccation, stomatal closure leads to drastic reductions in CO2 fixation and photorespiration. We could not identify alternative electron sinks as a solution to reduce ROS production. 3. On the supramolecular level, semicrystalline protein arrays were identified in thylakoid membranes in the desiccated state (see Fig. 3). On the electron transport level, a specific series of shut downs occur (summarized in Fig. 2). The main events include: Early shutdown of the ATPase activity, cessation of electron transport between cyt. bf complex and PSI (can reduce ROS formation at PSI); at higher dehydration levels uncoupling of LHCII from PSII and cessation of electron flow from PSII accompanied by crystal formation. The later could severe as a swift PSII reservoir during rehydration. The specific order of events in the course of dehydration and rehydration discovered in this project is indicative for regulated structural transitions specifically realized in resurrection plants. This detailed knowledge can serve as an interesting starting point for rationale genetic engineering of drought-tolerant crops.
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STUDY ON SHEAR BEHAVIOR OF BOX TYPE STEEL STRUCTURE CONSIDERING WELDING EFFECT. The Hong Kong Institute of Steel Construction, August 2022. http://dx.doi.org/10.18057/icass2020.p.325.
Повний текст джерелаАнотація:
Welding effect would reduce the bearing capacity and overall stability of the structure, whichhave many adverse effects on the structure. In order to determine the mechanical properties of box-type steel structure under welding effect, the effects of welding mode, welding quantity and position, and welding staggered joint size on its shear capacity were studied systematically. The results show that the shear capacity of the piecewise backward sequence welding is higher. The welding position has little influence on the shear bearing capacity, but the number of welding has a certain influence on the shear bearing capacity. The welding staggered joint size has a significant effect on shear capacity. Finally, the formula of ultimate shear capacity of welding space element is proposed based on welding staggered joint size.