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Статті в журналах з теми "Envelope function model"
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Zhang, X., C. E. Lee, and X. Shao. "Envelopes in multivariate regression models with nonlinearity and heteroscedasticity." Biometrika 107, no. 4 (June 17, 2020): 965–81. http://dx.doi.org/10.1093/biomet/asaa036.
Повний текст джерелаАнотація:
Summary Envelopes have been proposed in recent years as a nascent methodology for sufficient dimension reduction and efficient parameter estimation in multivariate linear models. We extend the classical definition of envelopes in Cook et al. (2010) to incorporate a nonlinear conditional mean function and a heteroscedastic error. Given any two random vectors ${X}\in\mathbb{R}^{p}$ and ${Y}\in\mathbb{R}^{r}$, we propose two new model-free envelopes, called the martingale difference divergence envelope and the central mean envelope, and study their relationships to the standard envelope in the context of response reduction in multivariate linear models. The martingale difference divergence envelope effectively captures the nonlinearity in the conditional mean without imposing any parametric structure or requiring any tuning in estimation. Heteroscedasticity, or nonconstant conditional covariance of ${Y}\mid{X}$, is further detected by the central mean envelope based on a slicing scheme for the data. We reveal the nested structure of different envelopes: (i) the central mean envelope contains the martingale difference divergence envelope, with equality when ${Y}\mid{X}$ has a constant conditional covariance; and (ii) the martingale difference divergence envelope contains the standard envelope, with equality when ${Y}\mid{X}$ has a linear conditional mean. We develop an estimation procedure that first obtains the martingale difference divergence envelope and then estimates the additional envelope components in the central mean envelope. We establish consistency in envelope estimation of the martingale difference divergence envelope and central mean envelope without stringent model assumptions. Simulations and real-data analysis demonstrate the advantages of the martingale difference divergence envelope and the central mean envelope over the standard envelope in dimension reduction.
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Zhang, Lei Yu, Rui Hua Zhuo, Li Jian Liu, and Shu Zhong Feng. "A Piecewise Function Smooth Strength Envelope Model." Applied Mechanics and Materials 182-183 (June 2012): 1069–73. http://dx.doi.org/10.4028/www.scientific.net/amm.182-183.1069.
Повний текст джерелаАнотація:
The method of trigonometric series is one of widely used methods for calculating artificial ground motion. But using this method the speed of time, it was found that the zero line must exist the phenomenon of drift. This text fore person the foundation of the research up, a kind of more perfect model of differentiable nonsingular strength envelope function is proposed .a better resolve this problem. Passing the calculation proved that the new method is reasonable and effective.
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Rodríguez-Coppola, H., J. L. Martínez-Cuellar, and R. Pérez-Álvarez. "Two-Band Envelope Function Model for Graded Interfaces." physica status solidi (b) 158, no. 2 (April 1, 1990): 481–91. http://dx.doi.org/10.1002/pssb.2221580209.
Повний текст джерела
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Dargahi-Noubary, G. R. "An envelope function model for forecasting athletics records." Journal of Forecasting 13, no. 1 (January 1994): 11–20. http://dx.doi.org/10.1002/for.3980130103.
Повний текст джерела
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Strzałka, Radosław, Łukasz Chuchra, and Janusz Wolny. "Envelope Function Analysis of Quasicrystals." Crystals 12, no. 4 (April 11, 2022): 536. http://dx.doi.org/10.3390/cryst12040536.
Повний текст джерелаАнотація:
Quasicrystals have attracted a growing interest in material science because of their unique properties and applications. Proper determination of the atomic structure is important in designing a useful application of these materials, for which a difficult phase problem of the structure factor must be solved. Diffraction patterns of quasicrystals consist of a periodic series of peaks, which can be reduced to a single envelope. Knowing the distribution of the diffraction image into series, it is possible to recover information about the phase of the structure factor without using time-consuming iterative methods. By the inverse Fourier transform, the structure factor can be obtained (enclosed in the shape of the average unit cell, or atomic surface) directly from the diffraction patterns. The method based on envelope function analysis was discussed in detail for a model 1D (Fibonacci chain) and 2D (Penrose tiling) quasicrystal. First attempts to apply this technique to a real Al-Cu-Rh decagonal quasicrystal were also made.
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Vencovský, Václav. "Roughness Prediction Based on a Model of Cochlear Hydrodynamics." Archives of Acoustics 41, no. 2 (June 1, 2016): 189–201. http://dx.doi.org/10.1515/aoa-2016-0019.
Повний текст джерелаАнотація:
Abstract The term roughness is used to describe a specific sound sensation which may occur when listening to stimuli with more than one spectral component within the same critical band. It is believed that the spectral components interact inside the cochlea, which leads to fluctuations in the neural signal and, in turn, to a sensation of roughness. This study presents a roughness model composed of two successive stages: peripheral and central. The peripheral stage models the function of the peripheral ear. The central stage predicts roughness from the temporal envelope of the signal processed by the peripheral stage. The roughness model was shown to account for the perceived roughness of various types of acoustic stimuli, including the stimuli with temporal envelopes that are not sinusoidal. It thus accounted for effects of the phase and the shape of the temporal envelope on roughness. The model performance was poor for unmodulated bandpass noise stimuli.
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Wu, Ru-Shan, Jingrui Luo, and Bangyu Wu. "Seismic envelope inversion and modulation signal model." GEOPHYSICS 79, no. 3 (May 1, 2014): WA13—WA24. http://dx.doi.org/10.1190/geo2013-0294.1.
Повний текст джерелаАнотація:
We recognized that the envelope fluctuation and decay of seismic records carries ultra low-frequency (ULF, i.e., the frequency below the lowest frequency in the source spectrum) signals that can be used to estimate the long-wavelength velocity structure. We then developed envelope inversion for the recovery of low-wavenumber components of media (smooth background), so that the initial model dependence of waveform inversion can be reduced. We derived the misfit function and the corresponding gradient operator for envelope inversion. To understand the long-wavelength recovery by the envelope inversion, we developed a nonlinear seismic signal model, the modulation signal model, as the basis for retrieving the ULF data and studied the nonlinear scale separation by the envelope operator. To separate the envelope data from the wavefield data (envelope extraction), a demodulation operator (envelope operator) was applied to the waveform data. Numerical tests using synthetic data for the Marmousi model proved the validity and feasibility of the proposed approach. The final results of combined [Formula: see text] (envelope-inversion for smooth background plus waveform-inversion for high-resolution velocity structure) indicated that it can deliver much improved results compared with regular full-waveform inversion (FWI) alone. Furthermore, to test the independence of the envelope to the source frequency band, we used a low-cut source wavelet (cut from 5 Hz below) to generate the synthetic data. The envelope inversion and the combined [Formula: see text] showed no appreciable difference from the full-band source results. The proposed envelope inversion is also an efficient method with very little extra work compared with conventional FWI.
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Albin, Nathan, Sergio Conti, and Georg Dolzmann. "Infinite-order laminates in a model in crystal plasticity." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 139, no. 4 (July 8, 2009): 685–708. http://dx.doi.org/10.1017/s0308210508000127.
Повний текст джерелаАнотація:
We consider a geometrically nonlinear model for crystal plasticity in two dimensions, with two active slip systems and rigid elasticity. We prove that the rank-1 convex envelope of the condensed energy density is obtained by infinite-order laminates, and express it explicitly via the 2F1 hypergeometric function. We also determine the polyconvex envelope, leading to upper and lower bounds on the quasiconvex envelope. The two bounds differ by less than 2%.
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Nirmal, Jagannath, Suprava Patnaik, Mukesh Zaveri, and Pramod Kachare. "Complex Cepstrum Based Voice Conversion Using Radial Basis Function." ISRN Signal Processing 2014 (February 6, 2014): 1–13. http://dx.doi.org/10.1155/2014/357048.
Повний текст джерелаАнотація:
The complex cepstrum vocoder is used to modify the speaker specific characteristics of the source speaker speech to that of the target speaker speech. The low time and high time liftering are used to split the calculated cepstrum into the vocal tract and the source excitation parameters. The obtained mixed phase vocal tract and source excitation parameters with finite impulse response preserve the phase properties of the resynthesized speech frame. The radial basis function is explored to capture the nonlinear mapping function for modifying the complex cepstrum based real and imaginary components of the vocal tract and source excitation of the speech signal. The state-of-the-art Mel cepstrum envelope and the fundamental frequency (F0) are considered to represent the vocal tract and the source excitation of the speech frame, respectively. Radial basis function is used to capture and formulate the nonlinear relations between the Mel cepstrum envelope of the source and target speakers. Mean and standard deviation approach is employed to modify the fundamental frequency (F0). The Mel log spectral approximation filter is used to reconstruct the speech signal from the modified Mel cepstrum envelope and fundamental frequency. A comparison of the proposed complex cepstrum based model has been made with the state-of-the-art Mel Cepstrum Envelope based voice conversion model with objective and subjective evaluations. The evaluation measures reveal that the proposed complex cepstrum based voice conversion system approximate the converted speech signal with better accuracy than the model based on the Mel cepstrum envelope based voice conversion.
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Qu, Zhipeng, Wei He, Mingyun Lv, and Houdi Xiao. "Large-Strain Hyperelastic Constitutive Model of Envelope Material under Biaxial Tension with Different Stress Ratios." Materials 11, no. 9 (September 19, 2018): 1780. http://dx.doi.org/10.3390/ma11091780.
Повний текст джерелаАнотація:
This paper reports the biaxial tensile mechanical properties of the envelope material through experimental and constitutive models. First, the biaxial tensile failure tests of the envelope material with different stress ratio in warp and weft directions are carried out. Then, based on fiber-reinforced continuum mechanics theory, an anisotropic hyperelastic constitutive model on envelope material with different stress ratio is developed. A strain energy function that characterizes the anisotropic behavior of the envelope material is decomposed into three parts: fiber, matrix and fiber–fiber interaction. The fiber–matrix interaction is eliminated in this model. A new simple model for fiber–fiber interaction with different stress ratio is developed. Finally, the results show that the constitutive model has a good agreement with the experiment results. The results can be used to provide a reference for structural design of envelope material.
Дисертації з теми "Envelope function model"
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ARCHETTI, Giulia. "Involucri evoluti a comportamento dinamico: tecnologie e modelli applicativi nel contesto geografico, normativo e imprenditoriale della Regione Emilia-Romagna." Doctoral thesis, Università degli studi di Ferrara, 2010. http://hdl.handle.net/11392/2389291.
Повний текст джерелаАнотація:
Introduction
The importance of connection between construction envelopes and environmental and technological systems is rising up thanks to the grow request to answer to environmental necessities and resources safe. Moreover the envelopes become a complex technologic machine, which are able to adjust automatically to environmental condition and weather changes. Facing these technical problems, architects must plan more flexible and active evolved envelopes with dynamic behaviour to adapt to the sudden changes of surrounding condition.
The principal problems are in particular the aspects related to the correct material choice and the study of physical and thermal principles of the envelope.
Every envelope is constituted of an external skin, an internal one and an air space buffer in the middle. According to the type of material we could discern between transparent, translucent and opaque envelope, everyone with specific characteristics.
The study refers in particular to the glassy-glassy envelope (made of a double glass skin), which is the principal field of research of our group.
Aims
The principal aim is to determine new universal application model, solution and use possibilities of glassy-glassy envelopes, studying the best and useful technical and physic parameters to improve the energy safe and environmental performance quality.
Step by step the middle aims were:
• Evolved envelope state of art definition;
• The critical analysis of lacking and mistakes about actual knowledge on evolved envelope;
• The study of material and component basing on previous analysis and current courses;
• Definition of instruments able to solve technical aspects and problems;
• Collection and schedules of existing projects;
• Application models of dynamic evolved envelope
Limits
Because the verification of normative applicability was easier in a regional contest than in an international one, the methodologies pointed out by this research concern only a regional background, even if the research was based on national and international quality projects,
Generic considerations about evolved envelopes are missed out. A more specific parameters dissertation was preferred to define physic phenomena limitation and application solutions.
Moreover the research concern only glassy-glassy enveloped, a field that permits a deeper tractability starting from the experience of Professor Fabio Conato and his collaborators (Arch Simona Cinti and Arch Giuseppe Camillo Santangelo) and from the elaboration of data collected about the construction of double skin envelope.
Methods
The results are based on a bibliographic revision of the literature and on a collection of expert opinion in the branch of envelope (planners, technicians and producers).
Project phases:
• Architectural characteristics and performances analysis of the evolved envelops. Definition of functional principles;
• Technical assay about the possibilities of envelope applications:
• Examination of energy safe plans already existing;
• Identification and consequences of application of existing normative and rules about quality environmental assessment and energy safe certification (both in UE, Italy and Emilia Romagna institution);
• Revision of documents concerning the need of dynamic envelope and quality verification instruments
The research is based on theoretical physic principles connecting the environment to the buildings, on the evaluation of environment phenomena on a realized construction, on the possibilities to manage energy natural fluxes, on building thermal balance and on technical components exploiting renewable sources to produce energy.
Results
The final results confirm the validity of dynamic evolved envelope to rise good and variable performance. Otherwise the dynamic technology is efficient in a restricted area and is necessary the application of different typology of the same system to optimize performances. The analysis of this model of envelope is important to define the interventional scenario and the application system.
The review of previous study also permits to analyze and rebuild prior hypothesis, particularly specifying the state of art relating envelope project and the lack of information, filling with new details.
Consequently possibilities of envelopes solutions, internal and external factors and physic phenomena were defined. According to the ongoing normative, new planning indications and issues of normative elaboration were furnished. Finally, thanks to a new quick and concrete instrument (planning guide), the final results of such a complex field could be easy comprehensible.
Recipient, development and future evolution
This research would be finalized to society and people who work in building trade field, in order to help them in planning. Moreover the evaluation about the actual normative should bring new elements to discuss and formulate again this instrument. Also technical evolution and innovation in double skin envelope, nowadays lacking and inaccurate, could help the project of new advanced component solution.
At the real end the research could show many solution apt to offer new evolved system
Particularly:
• Material: research in new material, production methods and components for wall face have a great importance to improve performance and characteristic of envelope;
• Components: in particular one of the principal criticism about the space between the two skin of the envelope;
• System: the grow request of performing wall face could transform the static system in a sort of dynamic system integrating both the wall and the air conditioning/healing system guarantying a thermal and visual comfort both in term of energy earn and use;
• Actual building integration: the use of envelope in re-qualifying and renovate old buildings could be an interesting field of research;
• Planner guide: this software is based on Emilia Romagna weather conditions. An implementation to other Italian and Europe reason should be necessary.
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Walha, Sonda. "Construction de solutions particulières de types ondes progressives pour le modèle de Frenkel-Kontorova et pour l’équation des ondes régularisée." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMIR29.
Повний текст джерелаАнотація:
Cette thèse porte sur la construction de solutions particulières de type ondes progressives ou ondes planes pour différentes équations aux dérivées partielles (EDP) et en particulier le modèle de Frenkel-Kontorova et une équation des ondes régularisée. Ce mémoire s’articule comme suit. Le chapitre 1 est destiné à une introduction générale dans laquelle je présente une motivation physique et un résumé de mon travail. Le chapitre 2 est destiné à l’étude d’existence et d’unicité des ondes progressives avec le terme d’accélération. Ce modèle consiste d’un système d’ODE qui décrit le mouvement de particules en interaction. Les applications les plus importantes que nous avons à l’esprit est le mouvement des défauts cristallins appelés dislocations. Pour ce modèle, nous montrons l’existence des ondes progressives sous des hypothèses très faibles. L’unicité de la vitesse a été étudiée ainsi que l’unicité du profil en utilisant les différents types du principe de maximum fort. Comme ce que nous savons, c’est le premier résultat concernant les ondes progressives pour un système accéléré, spatialement discret. Ce chapitre est un article publié à la revue Journal of Dynamic and Differential Equation : Existence and uniqueness of traveling wave for accelerated Frenkel-Kontorova model, Journal of Dynamic and Differential Equation : Volume 26, Issue 24 (2014), page 1133-1169. Le chapitre 3 est réservé à l’homogénéisation numérique du modèle Frenkel-Kontrova dans le cas amortie. Je présente deux méthodes pour calculer l’hamiltonien effectif: la méthode grand temps et la méthode de Newton. Quelques simulations de l’hamiltonien effectif sont fournies. Le chapitre 4 est destiné à l’étude d’équation d’onde dans un domaine périodique. Selon certaines hypothèses, je construis une solution d’onde plane pour le problème approché et je montre que cette solution satisfait certaines propriétés. Je définis un opérateur non local et un terme correcteur afin de contrôler les oscillations de la solution dans l’espace et dans le temps. Je prouve la construction d’une solution d’onde plane pour un problème approché en utilisant la notion de solution de viscositéThis thesis deals with the construction of particular solutions of traveling wave or plane wave for different equations partial derivative (EDP) and in particular the Frenkel-Kontorova model and a regularized wave equation. This memory is structured as follows. The chapter 1 is preserved for a general introduction in which i present a physical motivation and a abstract of my work. In chapter 2, I interested to the study the existence and uniqueness of traveling wave solution for the accelerated Frenkel-Kontorova model. This model consist in a system of ODE that describe the motion particles in interaction. The most important applications ihave inmind in the motion of cristal defects called dislocations. For this model, i prove the exxistence of traveling wave solutions under very weak assumptions. The uniqueness of the velocity is also studied as well the uniqueness of the profile which used ddifferent types of strpng maximum principle. As far as we know, this is the first result concerning traveling waves for accelerated, spatially discrete system. This chapter is an article published in the Journal Dynamic and Differential Equation:Existence and uniqueness of traveling wave for accelerated Frenkel-Kontorova model, Journal of dynamic and Differential Equation : Volume 26, Issue 24 (2014), page 1133-1169. In chapter 3, i interested in the numerical homogenization of fully overdomped frenkel-Kontorova model. I present two methods for computing the effective hamiltonian : large time method and Newton-like method. Some simulations of the effective hamiltonian are provided. Le chapter 4 is preserved to the study a wave equation in a periodic medium. Under certain assumption, i construct a plane wave like solution, and show that this solution satisfy some properties. I define a non- local operator and a term corrector in order to control the oscillations of the solution in space and in time. We prove the construction of a plane wave like solution for the approched problem using the notion of viscosity solution
Книги з теми "Envelope function model"
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Lattman, Eaton E., Thomas D. Grant, and Edward H. Snell. Pushing the Envelope. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199670871.003.0014.
Повний текст джерелаАнотація:
Direct electron density determination from SAXS data opens up new opportunities. The ability to model density at high resolution and the implicit direct estimation of solvent terms such as the hydration shell may enable high-resolution wide angle scattering data to be used to calculate density when combined with additional structural information. Other diffraction methods that do not measure three-dimensional intensities, such as fiber diffraction, may also be able to take advantage of iterative structure factor retrieval. While the ability to reconstruct electron density ab initio is a major breakthrough in the field of solution scattering, the potential of the technique has yet to be fully uncovered. Additional structural information from techniques such as crystallography, NMR, and electron microscopy and density modification procedures can now be integrated to perform advanced modeling of the electron density function at high resolution, pushing the boundaries of solution scattering further than ever before.
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Back, Kerry E. Dynamic Portfolio Choice. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190241148.003.0009.
Повний текст джерелаАнотація:
The first‐order condition for optimal portfolio choice is called the Euler equation. Optimal consumption can be computed by a static approach in a dynamic complete market and by orthogonal projection for a quadratic utility investor. Dynamic programming and the Bellman equation are explained. The envelope condition and hedging demands are explained. Investors with CRRA utility have CRRA value functions. Whether the marginal value of wealth is higher for a CRRA investor in good states or in bad states depends on whether risk aversion is less than or greater than 1. With IID returns, the optimal portfolio for a CRRA investor is the same as the optimal portfolio in a single‐period model.
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Fawcett, Paul, Matthew Flinders, Colin Hay, and Matthew Wood. Conclusion. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198748977.003.0013.
Повний текст джерелаАнотація:
This chapter returns to the idea of ‘nexus politics’ and the collection’s overall concern with how depoliticization functions to reinforce anti-politics in the context of changes in governance. We organize an agenda for further research around theoretical, methodological, and empirical themes. Theoretically, we argue that further work is needed to better account for how and why depoliticization and politicization occur, and on which forms of politicization promote choice, deliberation, and agency. Methodologically, we need to develop analytical models that map out what institutional and discursive configurations make choice and collective agency appear more or less visible. We need to keep pushing the envelope by examining how depoliticization operates in unconventional arenas. While much more work still needs to be done, this book makes a modest yet distinctive contribution towards a better understanding of ‘nexus politics’ and the growth of anti-politics as one of the most significant issues of our time.
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Vaheri, Antti, James N. Mills, Christina F. Spiropoulou, and Brian Hjelle. Hantaviruses. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780198570028.003.0035.
Повний текст джерелаАнотація:
Hantaviruses (genus Hantavirus, family Bunyaviridae) are rodent- and insectivore-borne zoonotic viruses. Several hantaviruses are human pathogens, some with 10-35% mortality, and cause two diseases: hemorrhagic fever with renal syndrome (HFRS) in Eurasia, and hantavirus cardiopulmonary syndrome (HCPS) in the Americas. Hantaviruses are enveloped and have a three-segmented, single-stranded, negative-sense RNA genome. The L gene encodes an RNA-dependent RNA polymerase, the M gene encodes two glycoproteins (Gn and Gc), and the S gene encodes a nucleocapsid protein. In addition, the S genes of some hantaviruses have an NSs open reading frame that can act as an interferon antagonist. Similarities between phylogenies have suggested ancient codivergence of the viruses and their hosts to many authors, but increasing evidence for frequent, recent host switching and local adaptation has led to questioning of this model. Infected rodents establish persistent infections with little or no effect on the host. Humans are infected from aerosols of rodent excreta, direct contact of broken skin or mucous membranes with infectious virus, or rodent bite. One hantavirus, Andes virus, is unique in that it is known to be transmitted from person-to-person. HFRS and HCPS, although primarily affecting kidneys and lungs, respectively, share a number of clinical features, such as capillary leakage, TNF-, and thrombocytopenia; notably, hemorrhages and alterations in renal function also occur in HCPS and cardiac and pulmonary involvement are not rare in HFRS. Of the four structural proteins, both in humoral and cellular immunity, the nucleocapsid protein appears to be the principal immunogen. Cytotoxic T-lymphocyte responses are seen in both HFRS and HCPS and may be important for both protective immunity and pathogenesis. Diagnosis is mainly based on detection of IgM antibodies although viral RNA (vRNA) may be readily, although not invariably, detected in blood, urine and saliva. For sero/genotyping neutralization tests/RNA sequencing are required. Formalin-inactivated vaccines have been widely used in China and Korea but not outside Asia. Hantaviruses are prime examples of emerging and re-emerging infections and, given the limited number of rodents and insectivores thus far studied, it is likely that many new hantaviruses will be detected in the near future.
Частини книг з теми "Envelope function model"
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Burt, M. G. "Exact Envelope Function Equations for Microstructures and the Particle in a Box Model." In Band Structure Engineering in Semiconductor Microstructures, 99–109. Boston, MA: Springer New York, 1989. http://dx.doi.org/10.1007/978-1-4757-0770-0_8.
Повний текст джерела
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Igor, Vurgaftman. "Basics of Envelope-Function Theory." In Bands and Photons in III-V Semiconductor Quantum Structures, 239–70. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198767275.003.0008.
Повний текст джерелаАнотація:
The chapter shows how the bulk theory described in Part I can be generalized within the envelope-function framework to model the band structure of layered materials with quantum confinement of carriers such as quantum wells or superlattices. In practice, the approach amounts to substituting derivatives for wavevector components in suitably chosen Hamiltonians as well as augmenting them with interface terms. It also discusses the spin splitting of the states of the quantum structures that arises from structural and intrinsic asymmetries.
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Karadimas, Petros. "Stochastic Modeling of Narrowband Fading Channels with Three Dimensional Diffuse Scattering." In Handbook of Research on Heterogeneous Next Generation Networking, 361–81. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-108-7.ch016.
Повний текст джерелаАнотація:
This chapter studies a composite stochastic model, in which the diffuse component arises from three dimensional (3-D) multipath scattering. That case occurs especially in dense scattering environments, in which the tall obstacles cause arrival of multipath power in the elevation plane, besides that arriving in the azimuth one. Also the multipath components are assumed to arrive at the mobile receiver in specific angular sectors at the azimuth receiver’s plane. The last is physically justified by multipath power blocking due to the channel obstacles (shadow fading), or/and lack of scattering objects at specific angular directions, or/and directional antennas utilization. An extended Suzuki model, where the Rician process for the diffuse scattering component is multiplied by a lognormal one, is considered as an appropriate composite model. The most important metrics of the model are presented, according to its assumptions. More specifically, from the closed form autocorrelation function, the Doppler power spectral density (PSD) of the diffuse component can be analytically derived. Afterwards exact solutions for the envelope and phase probability density functions (PDF’s) are presented. Exact solutions are also derived for the second order statistics, i.e. the level crossing rate (LCR) and the average duration of fades (ADF’s). An efficient deterministic simulation scheme will be presented, which implements the analytical model on a digital computer. Finally a curve fitting of the LCR to real world data, drawn from channel measurements, will demonstrate the flexibility and usefulness of the extended Suzuki model.
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Ostrosi, Egon, Jean-Bernard Bluntzer, and Josip Stjepandić. "A CAD Material Skeleton-Based Approach for Sustainable Design." In Advances in Transdisciplinary Engineering. IOS Press, 2020. http://dx.doi.org/10.3233/atde200133.
Повний текст джерелаАнотація:
In recent years, the development and application of sustainable product design have become a hot spot. With the development of computer technology as the core of the comprehensive technology, product management information system should integrate the sustainable material specifications early in process design. This paper proposes a conceptual model based on the concept of CAD skeleton where the material and function of the constituent elements are highly integrated to achieve sustainable products. A skeleton contains formally the following information: engineering requirements, performance requirements, materials and morphology. This information is defined by defined firstly by attachment, which relates to the immediate proximity of the importing and exporting of design loads; secondly by the functional structure which defines the simplified morphology to channel the loads and thirdly the envelope, which defines where the morphology of the part can be without interfering with others. Using the proposed formalism, the morphology of the product (geometry and topology) is formally driven by material requirements. Therefore, this approach allows the designer to design different product forms according to the material requirements of clients. An application shows the interest of the approach.
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Björk, Tomas. "Optimal Stopping Theory and American Options." In Arbitrage Theory in Continuous Time, 376–96. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198851615.003.0028.
Повний текст джерелаАнотація:
In this chapter we present the dynamic programming approach to optimal stopping problems. We start by presenting the discrete time theory, deriving the relevant Bellman equation. We present the Snell envelope and prove the Snell Envelope Theorem. For Markovian models we explore the connection to alpha-excessive functions. The continuous time theory is presented by deriving the free boundary value problem connected to the stopping problem, and we also derive the associated system of variational inequalities. American options are discussed in some detail.
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Fernández-Agüera, Jesica, Samuel Domínguez-Amarillo, and Juan José Sendra. "Forecasting Energy Impact in Multifamily Buildings Through Airtightness Models." In Practice, Progress, and Proficiency in Sustainability, 72–95. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-7023-4.ch004.
Повний текст джерелаАнотація:
Southern European areas are traditionally considered to have a benign climate and therefore most homes often do not have controlled ventilation systems or air conditioning. Our society faces challenging situations with global pandemics and health emergencies, while housing provides the basic elements of refuge and activity. A profound transformation of social and labor dynamics is underway, increasing at-home presence, hence the capital importance of improving building envelopes to reduce energy demand and to increase occupant comfort levels in order to ensure their protective function. Air leakage is one of the key factors both in indoor air quality and energy demand. This study aims to explore the sensitivity of energy demand to airtightness. A representative set of multifamily buildings, built in the last 20 years in Seville, is analyzed. The results show that air permeability has a significant effect on energy demand in the sample studied. Although impact is greater in severe climates, it needs to be considered in temperate climates, especially when more time is spent at home.
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Koch, Christof. "Bursting Cells." In Biophysics of Computation. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195104912.003.0022.
Повний текст джерелаАнотація:
Some neurons throughout the animal kingdom respond to an intracellular current injection or to an appropriate sensory stimulus with a stereotypical sequence of two to five fast spikes riding upon a slow depolarizing envelope. The entire event, termed a burst, is over within 10-40 msec and is usually terminated by a profound afterhyperpolarization (ΑΗΡ). Such bursting cells are not a random feature of a certain fraction of all cells but can be identified with specific neuronal subpopulations. What are the mechanisms generating this intrinsic firing pattern and what is its meaning? Bursting cells can easily be distinguished from a cell firing at a high maintained frequency by the fact that bursts will persist even at a low firing frequency. As illustrated by the thalamic relay cell of Fig. 9.4, some cells can switch between a mode in which they predominantly respond to stimuli via single, isolated spikes and one in which bursts are common. Because we believe that bursting constitutes a special manner of signaling important information, we devote a single, albeit small chapter to this topic. In the following, we describe a unique class of cells that frequently signal with bursts, and we touch upon the possible biophysical mechanisms that give rise to bursting. We finish this excursion by focussing on a functional study of bursting cells in the electric fish and speculate about the functional relevance of burst firing. Neocortical cells are frequently classified according to their response to sustained current injections. While these distinctions are not all or none, there is broad agreement for three classes: regular spiking, fast spiking, and intrinsically bursting neurons (Connors, Gutnick, and Prince, 1982; McCormick et al., 1985; Connors and Gutnick, 1990; Agmon and Connors, 1992; Baranyi, Szente, and Woody, 1993; Nuńez, Amzica, and Steriade, 1993; Gutnick and Crill, 1995; Gray and McCormick, 1996). Additional cell classes have been identified (e.g., the chattering cells that fire bursts of spikes with interburst intervals ranging from 15 to 50 msec; Gray and McCormick, 1996), but whether or not they occur widely has not yet been settled. The cells of interest to us are the intrinsically bursting cells.
Тези доповідей конференцій з теми "Envelope function model"
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Yager, Dean, Steven Mathews, Kenneth J. Ciuffreda, and Ellen Richter Ettinger. "Spatial Frequency Discrimination in Amblyopia: A Comparison of Anisometropes and Strabismics." In Noninvasive Assessment of Visual Function. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/navf.1985.wb4.
Повний текст джерелаАнотація:
Recent models of pattern vision have proposed that there are a number of individual neural channels, each selectively sensitive to a relatively narrow band of spatial frequencies. Together these channels act as a band-pass filter whose envelope is the spatial contrast sensitivity function of the visual system. The multiple spatial frequency channels model is invoked to account for a variety of visual experimental results.
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Xiangyu Zhou, Francesco Bertazzi, Michele Goano, and Giovanni Ghione. "A spurious-solution-free envelope function model for quantum-confined wurtzite nanostructures." In 14th International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD 2014). IEEE, 2014. http://dx.doi.org/10.1109/nusod.2014.6935339.
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Brahimi, Malek, and Sidi Berri. "Sensitivity of Response Spectra to ARMA Model Process." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48635.
Повний текст джерелаАнотація:
The sensitivity analysis in this study focuses on the sensitivity of response spectra to the number of peaks in the envelope function and the order of the Autoregressive Moving Average of order p, q (ARMA( p,q)) process used to represent an earthquake time series. Results consist of two sets of response spectra: one set corresponds to the one peak for envelope function and ARMA(2,1), the second set involves a change in the number of peaks assumed and the order p, q of fitted ARMA(2,1) models. For comparison purposes, response data were normalized by dividing all spectral ordinates by the corresponding ordinates for the one peak, ARMA(2,1) models for the same earthquake. It was conclude that, models of order (2,1) are sufficient to estimate the damage effect of an earthquake with relatively few parameters.
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Wang, Kai, Zhuang Xu, Lei Zhang, Zhiqiang Yu, Chao Yu, and Jianfeng Zhai. "A 2-D Envelope Combination Selective Affine Function-Based Behavioral Model for Concurrent Dual-Band Power Amplifiers." In 2022 IEEE MTT-S International Wireless Symposium (IWS). IEEE, 2022. http://dx.doi.org/10.1109/iws55252.2022.9977464.
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Oliver, James H., and Philip C. Theruvakattil. "Sculptured Surface Model Synthesis Based on Functional Design Constraints." In ASME 1993 Design Technical Conferences. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/detc1993-0426.
Повний текст джерелаАнотація:
Abstract A technique is presented for the synthesis of sculptured surface models subject to several functional design constraints. A design environment is specified as a collection of polyhedral models which represent components in the vicinity of the design surface, or regions which the surface should avoid. The primary functional constraint is formulated as a proximity penalty function such that the design surface is induced to avoid a tolerance envelope around each component. In addition, a constraint based on surface area is formulated to counteract the expansion effect of the proximity constraint. Secondary design constraints are formulated to maintain consistent surface topology, and exploit part symmetry. Surface synthesis is thus formulated as an optimization problem and solved via simulated annealing. Several example applications are presented to demonstrate the capabilities of the technique.
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Oughstun, Kurt E., Patrick T. Connors, and George C. Sherman. "Finite turn-on time effects on the transient phenomena in dispersive pulse propagation." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/oam.1986.fr9.
Повний текст джерелаАнотація:
To study the effects of a finite turn-on time on the transient phenomena associated with dispersive pulse propagation, we consider the propagated field in a Lorentz medium due to an input hyperbolic-tangent modulated signal f(t) = u (t) sin(ωct) of carrier frequency ω c with initial pulse envelope where the parameter β, which is indicative of the rapidity of turn-on of the signal, is real and positive. In the limit as β → ∞ this initial envelope function approaches a unit step function. The dynamic evolution of the propagated field is described via the dynamics of the saddle points in the complex ω plane that are associated with the complex phase function appearing in the integral representation of the propagated field and their interaction with the simple pole singularities of the spectrum ũ (ω − ω c ) of the intial pulse envelope function. This analysis shows that the precursor fields that are characteristic of the input unit step-function modulated signal will persist nearly unchanged for the input hyperbolic-tangent modulated signal for values of β of the order of δ or greater, where δ is the damping constant of the Lorentz model medium. As β decreases below δ, the precursor fields become less important and the field becomes quasimonochromatic.
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Wilson, Bruce H., and Cem Erin. "Robust Performance Analysis of Vibration Isolation Tables Using Tree-Structured Transfer Functions." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0447.
Повний текст джерелаАнотація:
Abstract The coefficients of physically-based models are often only known within certain bounds. Such parameter uncertainty complicates the control design problem. As eliminating all uncertainty is not a realistic option, formulating the model so that its behavior over the entire uncertainty space is easily determined can facilitate design and analysis. The model form suggested in this paper is a tree-structured transfer function. Bond graph theory provides the means to synthesize a transfer function with this structure. Both tree-structured and conventional transfer functions of a vibration isolation table, with five uncertain parameters, have been synthesized, and the former simplified the robust analysis problem more than the latter. The tree-structured transfer functions allowed the response envelope to be easily determined over key frequency ranges. The advantages of tree-structured over conventional transfer functions demonstrated in this paper suggest that this alternate form may be better suited for both nominal and robust analysis.
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Alrumaih, Abdulrahman W., Kingsley Kanu, and Zahra Sakhin. "Identifying Optimal Operating Envelope in Horizontal Wells Producing from Dual Permeability Media." In International Petroleum Technology Conference. IPTC, 2023. http://dx.doi.org/10.2523/iptc-22777-ea.
Повний текст джерелаАнотація:
Abstract In this paper, we present an integrated workflow utilizing a numerical model to identify optimal operating envelope for horizontal wells producing from dual permeability media. A synthetic dual permeability numerical model comprised of critical components namely: fracture and matrix permeabilities, matrix-fracture conductivity (shape factor), and fracture distribution based on Discrete Fracture Network (DFN) scheme was built. In addition, two horizontal producers completed with Inflow-Control – Devices (ICDs) and as open-hole respectively, are also connected to the model. Rigorous sensitivity analysis is implemented on these key parameters using the dynamic model under Equalspacing sampling scheme with well oil rate as the objective function. Range of values on each variable are typical for naturally fractured reservoirs. In addition, detailed sensitivity on ICD parameters such as flow resistance ratings are performed. Results from the analysis are presented in cumulative probability function identifying most likely, pessimistic and optimistic values. Among all the variables, Matrix-fracture transmissibility has most impact. Unfortunately, it is often neglected when designing horizontal wells in dual permeability reservoirs. Current practice pays most attention on permeability contrast lack of consensus in the industry on best technique for its estimation. Most common methodologies applied are Kazemi and Warren-Roots. Nevertheless, it plays a critical role in describing dual permeability subsurface flow mechanism. Most significantly, it is widely acknowledged that beaning up choke sizes enhances production performance of wells connected to dual permeability. However, in this study, we have been able to establish operating limits for this phenomenon. Matrix-fracture transmissibility could significantly influence a producer, which has not intersected high permeability streaks. Our study clearly demonstrates this observation using high-resolution dual permeability dynamic model. In addition, by performing multi-variate characterization, we establish operating envelope for optimizing well production performance in dual media systems through choke size settings.
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Campbell, I. H., and P. M. Fauchet. "Raman line shape in semiconductor microcrystals." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/oam.1985.fr2.
Повний текст джерелаАнотація:
Microcrystal sizes below 100 Å can in principle be easily measured from an analysis of the Raman-Stokes line shape. Richter et al.1 have shown that the confinement of phonons inside silicon grains of spherical shape leads to downshifting, broadening, and asymmetrization of the Raman line. In their model, phonons with finite wave vectors contribute to the line through an uncertainty principle argument. For the phonon envelope function, Richter selected a Gaussian whose magnitude is one-half at the grain boundary. We have now calculated the Stokes line for various microcrystalline semi-conductors as a function of grain size, assuming different envelope functions, and in particular that predicted by a simple theory. In silicon, we obtain significant departures from the size which can be deduced from Richter’s calculations. This may explain the often observed discrepancy between Raman and TEM results.2 In addition, we have calculated the Stokes line for various shapes, including columnar grains. These calculations are compared to measurements that we performed in various microcrystalline films having spherical or columnar grains. Finally, we discuss the influence of surface phonons, intragrain defects, and grain boundary material.
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Bélanger, P. A. "Soliton laser: a nonlinear model." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/oam.1990.thp3.
Повний текст джерелаАнотація:
I derive a nonlinear differential equation for the pulse envelope propagating into a soliton laser in which the output coupling and the coupling of the external nonlinear cavity are distributed along the gain medium of the main cavity. For a mismatch phase angle of π/2 between the two cavities, a stable opical soliton is the solution to the differential equation for negative dispersion (soliton into the fiber), as well as for positive dispersion, of the nonlinear external medium. The predicted width of the soliton pulse is a function of the coupling factor and of the intensity into the optical fiber. I also show that the operation of the soliton laser for this stable regime is similar to passive mode locking by a fast saturable absorber. Dark soliton is another possible regime. However, the gain required io sustain it is always higher than that required for the bright-soliton regime. For a critical value of the gain relative to the dispersion, another short-pulse regime is predicted that is in competition with the soliton regime. Bistable operation of the soliton laser is, therefore, possible at this point.
Звіти організацій з теми "Envelope function model"
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Sitaraman, S., S. Kim, and B. Anderson. Functional Bounding Content Envelope for Gamma and Neutron Emitting Isotopes in the Model 9977 Packaging. Office of Scientific and Technical Information (OSTI), October 2013. http://dx.doi.org/10.2172/1108842.
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Sitaraman, S., S. Kim, and B. Anderson. Functional Bounding Content Envelope for Gamma and Neutron Emitting Isotopes in the Model 9977 Packaging. Office of Scientific and Technical Information (OSTI), April 2014. http://dx.doi.org/10.2172/1149563.
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Dudley, Lynn M., Uri Shani, and Moshe Shenker. Modeling Plant Response to Deficit Irrigation with Saline Water: Separating the Effects of Water and Salt Stress in the Root Uptake Function. United States Department of Agriculture, March 2003. http://dx.doi.org/10.32747/2003.7586468.bard.
Повний текст джерелаАнотація:
Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.
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Chen, Junping, Zach Adam, and Arie Admon. The Role of FtsH11 Protease in Chloroplast Biogenesis and Maintenance at Elevated Temperatures in Model and Crop Plants. United States Department of Agriculture, May 2013. http://dx.doi.org/10.32747/2013.7699845.bard.
Повний текст джерелаАнотація:
specific objectives of this proposal were to: 1) determine the location, topology, and oligomerization of FtsH11 protease; 2) identify the substrate/s of FtsH11 and the downstream components involved in maintaining thermostability of chloroplasts; 3) identify new elements involved in FtsH11 protease regulatory network related to HT adaptation processes in chloroplast; 4) Study the role of FtsH11 homologs from crop species in HT tolerance. Background to the topic: HT-tolerant varieties that maintain high photosynthetic efficiency at HT, and cope better with daily and seasonal temperature fluctuations are in great need to alleviate the effect of global warming on food production. Photosynthesis is a very complex process requiring accurate coordination of many complex systems and constant adjustments to the changing environments. Proteolytic activities mediated by various proteases in chloroplast are essential part of this process and critical for maintaining normal chloroplast functions under HT. However, little is known about mechanisms that contribute to adaptation of photosynthetic processes to HT. Our study has shown that a chloroplast-targeted Arabidopsis FtsH11 protease plays an essential and specific role in maintaining thermostability of thylakoids and normal photosynthesis at moderate HT. We hypothesized that FtsH11 homologs recently identified in other plant species might have roles similarly to that of AtFtsH1. Thus, dissecting the underlying mechanisms of FtsH11 in the adaptation mechanisms in chloroplasts to HT stress and other elements involved will aid our effort to produce more agricultural products in less favorable environments. Major conclusions, solutions, achievements - Identified the chloroplast inner envelope membrane localization of FtsH11. - Revealed a specific association of FtsH11 with the a and b subunits of CPN60. - Identified the involvement of ARC6, a protein coordinates chloroplast division machineries in plants, in FtsH11 mediated HT adaptation process in chloroplast. -Reveal possible association of a polyribonucleotide nucleotidyltransferase (cpPNPase), coded by At3G03710, with FtsH11 mediated HT adaptation process in chloroplast. - Mapped 4 additional loci in FtsH11 mediated HT adaptation network in chloroplast. - Demonstrated importance of the proteolytic activity of FtsH11 for thermotolerance, in addition to the ATPase activity. - Demonstrated a conserved role of plant FtsH11 proteases in chloroplast biogenesis and in maintaining structural and functional thermostability of chloroplast at elevated temperatures. Implications, both scientific and agricultural:Three different components interacting with FtsH11 were identified during the course of this study. At present, it is not known whether these proteins are directly involved in FtsH11mediated thermotolerance network in chloroplast and/or how these elements are interrelated. Studies aiming to connect the dot among biological functions of these networks are underway in both labs. Nevertheless, in bacteria where it was first studied, FtsH functions in heat shock response by regulating transcription level of σ32, a heat chock factor regulates HSPsexpression. FtsH also involves in control of biosynthesis of membrane components and quality control of membrane proteins etc. In plants, both Arc 6 and CPN60 identified in this study are essential in chloroplast division and developments as mutation of either one impairs chloroplast division in Arabidopsis. The facts that we have found the specific association of both α and β CPN60 with FtsH11 protein biochemically, the suppression/ enhancement of ftsh11 thermosensitive phenotype by arc6 /pnp allele genetically, implicate inter-connection of these networks via FtsH11 mediated network(s) in regulating the dynamic adaptation processes of chloroplast to temperature increases at transcriptional, translational and post-translational levels. The conserved role of FtsH11 proteases in maintaining thermostability of chloroplast at HT demonstrated here provides a foundation for improving crop photosynthetic performance at high temperatures.