Bibliografie tematiche / Derivative propagation method

Indice

Articoli di riviste
Tesi
Capitoli di libri
Atti di convegni
Rapporti di organizzazioni

Letteratura scientifica selezionata sul tema "Derivative propagation method"

Autore: Grafiati

Pubblicato: 1 marzo 2025

Cita una fonte nei formati APA, MLA, Chicago, Harvard e in molti altri stili

Scegli il tipo di fonte:

Consulta la lista di attuali articoli, libri, tesi, atti di convegni e altre fonti scientifiche attinenti al tema "Derivative propagation method".

Accanto a ogni fonte nell'elenco di riferimenti c'è un pulsante "Aggiungi alla bibliografia". Premilo e genereremo automaticamente la citazione bibliografica dell'opera scelta nello stile citazionale di cui hai bisogno: APA, MLA, Harvard, Chicago, Vancouver ecc.

Puoi anche scaricare il testo completo della pubblicazione scientifica nel formato .pdf e leggere online l'abstract (il sommario) dell'opera se è presente nei metadati.

Articoli di riviste sul tema "Derivative propagation method"

Kim, Hyo Jin, Sang Ho Lee e Moon Kyum Kim. "Prediction of Crack Propagation under Dynamic Loading Conditions by Using the Enhanced Point Collocation Meshfree Method". Key Engineering Materials 324-325 (novembre 2006): 1059–62. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.1059.

Testo completo

Abstract (sommario):

An efficient and accurate numerical program with enhanced point collocation meshfree method is developed to simulate crack propagation under dynamic loading conditions. The enhanced meshfree method with point collocation formulation and derivative approximation in solids is presented. This study also presents the crack propagation criterion and computation of propagating direction, and the total structure of the numerical program named PCMDYC(Point Collocation Meshfree method for DYnamic Crack propagation). Several examples of crack propagation under dynamic loads are analyzed to simulate the arbitrary crack propagation under dynamic loads. The results show that PCMDYC predicts the propagating path of crack under dynamic loading conditions accurately and robustly.

Gli stili APA, Harvard, Vancouver, ISO e altri

Trahan, Corey J., Robert E. Wyatt e Bill Poirier. "Multidimensional quantum trajectories: Applications of the derivative propagation method". Journal of Chemical Physics 122, n. 16 (22 aprile 2005): 164104. http://dx.doi.org/10.1063/1.1884606.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Liao, Xuan, Tong Zhou, Longlong Zhang, Xiang Hu e Yuanxi Peng. "A Method for Calculating the Derivative of Activation Functions Based on Piecewise Linear Approximation". Electronics 12, n. 2 (4 gennaio 2023): 267. http://dx.doi.org/10.3390/electronics12020267.

Testo completo

Abstract (sommario):

Nonlinear functions are widely used as activation functions in artificial neural networks, which have a great impact on the fitting ability of artificial neural networks. Due to the complexity of the activation function, the computation of the activation function and its derivative requires a lot of computing resources and time during training. In order to improve the computational efficiency of the derivatives of the activation function in the back-propagation of artificial neural networks, this paper proposes a method based on piecewise linear approximation method to calculate the derivative of the activation function. This method is hardware-friendly and universal, it can efficiently compute various nonlinear activation functions in the field of neural network hardware accelerators. In this paper, we use least squares to improve a piecewise linear approximation calculation method that can control the absolute error and get less number of segments or smaller average error, which means fewer hardware resources are required. We use this method to perform a segmented linear approximation to the original or derivative function of the activation function. Both types of activation functions are substituted into a multilayer perceptron for binary classification experiments to verify the effectiveness of the proposed method. Experimental results show that the same or even slightly higher classification accuracy can be achieved by using this method, and the computation time of the back-propagation is reduced by 4–6% compared to the direct calculation of the derivative directly from the function expression using the operator encapsulated in PyTorch. This shows that the proposed method provides an efficient solution of nonlinear activation functions for hardware acceleration of neural networks.

Gli stili APA, Harvard, Vancouver, ISO e altri

Irshad, Hajira, Mehnaz Shakeel, Imtiaz Ahmad, Hijaz Ahmad, Chutarat Tearnbucha e Weerawat Sudsutad. "Simulation of generalized time fractional Gardner equation utilizing in plasma physics for non-linear propagation of ion-acoustic waves". Thermal Science 27, Spec. issue 1 (2023): 121–28. http://dx.doi.org/10.2298/tsci23s1121i.

Testo completo

Abstract (sommario):

In this work, radial basis function collocation method (RBFCM) is implemented for generalized time fractional Gardner equation (GTFGE). The RBFCM is meshless and easy-to-implement in complex geometries and higher dimensions, therefore, it is highly demanding. In this work, the Caputo derivative of fractional order ? ? (0, 1] is used to approximate the first order time derivative whereas, Crank-Nicolson scheme is hired to approximate space derivatives. The numerical solutions are presented and discussed, which demonstrate that the method is effective and accurate.

Gli stili APA, Harvard, Vancouver, ISO e altri

Rabie, Wafaa B., Hamdy M. Ahmed, Taher A. Nofal e Soliman Alkhatib. "Wave solutions for the (3+1)-dimensional fractional Boussinesq-KP-type equation using the modified extended direct algebraic method". AIMS Mathematics 9, n. 11 (2024): 31882–97. http://dx.doi.org/10.3934/math.20241532.

Testo completo

Abstract (sommario):

<p>In this study, we introduce the new (3+1)-dimensional $ \beta $-fractional Boussinseq-Kadomtsev-Petviashvili (KP) equation that describes the wave propagation in fluid dynamics and other physical contexts. By using the modified extended direct algebraic method, we investigate diverse wave solutions for the proposed fractional model. The acquired solutions, include (dark, bright) soliton, hyperbolic, rational, exponential, Jacobi elliptic function, and Weierstrass elliptic doubly periodic solutions. The primary objective is to investigate the influence of fractional derivatives on the characteristics and dynamics of wave solutions. Graphical illustrations are presented to demonstrate the distinct changes in the amplitude, shape, and propagation patterns of the soliton solutions as the fractional derivative parameters are varied.</p>

Gli stili APA, Harvard, Vancouver, ISO e altri

Zeng, Huahui, Yanxiang Wang, Yang Zhou, Huijie Meng, Qigang Zhou e Baozhong Jin. "Accurate Pseudo-Spectral Acoustic Wave Modelling with Time Dispersion Elimination". Applied Sciences 14, n. 19 (27 settembre 2024): 8725. http://dx.doi.org/10.3390/app14198725.

Testo completo

Abstract (sommario):

We propose an accurate method for modeling acoustic wave propagation. The spatial derivatives are calculated using Fourier transform to reduce spatial numerical dispersion. The standard staggered grid is adopted to suppress the non-causal ringing artifacts as in the traditional pseudo-spectral method. Moreover, to eliminate time dispersion arising from the discretization of the time derivative, an additional time-dispersion elimination term is introduced. As a result, the present method not only retains the advantages of the conventional pseudo-spectral method such as coarser spatial sampling or higher spatial derivative approximation accuracy, but also achieves higher temporal derivative approximation accuracy due to the adoption of the additional time-dispersion elimination term. Numerical examples demonstrate that the temporal dispersion elimination process can be contaminated by spatial numerical dispersion. Thus, the temporal and spatial numerical dispersions should be handled simultaneously, as proposed in this paper, to achieve accurate acoustic simulation.

Gli stili APA, Harvard, Vancouver, ISO e altri

Soliman, Mahmoud, Hamdy M. Ahmed, Niveen Badra, Taher A. Nofal e Islam Samir. "Highly dispersive gap solitons for conformable fractional model in optical fibers with dispersive reflectivity solutions using the modified extended direct algebraic method". AIMS Mathematics 9, n. 9 (2024): 25205–22. http://dx.doi.org/10.3934/math.20241229.

Testo completo

Abstract (sommario):

<p>We investigated the dynamics of highly dispersive nonlinear gap solitons in optical fibers with dispersive reflectivity, utilizing a conformable fractional derivative model. The modified extended direct algebraic method was employed to obtain various soliton solutions, including bright solitons and singular solitons, as well as hyperbolic and trigonometric solutions. The key findings demonstrated that the fractional derivative parameter ($ \alpha $) can effectively control the wave propagation, causing a shift in the wave signal while maintaining the same amplitude. This is a novel contribution, as the ability to control soliton properties through the conformable derivative is explored for the first time in this work. The results showcase the significant influence of fractional derivatives in shaping the characteristics of the soliton solutions, which is crucial for accurately modeling the dispersive and nonlocal effects in optical fibers. This research provides insights into the potential applications of fractional calculus in the design and optimization of photonic devices for optical communication systems.</p>

Gli stili APA, Harvard, Vancouver, ISO e altri

Hsu, Yupai P. "Multilayer dielectric inversion for electromagnetic propagation logging". GEOPHYSICS 57, n. 10 (ottobre 1992): 1260–69. http://dx.doi.org/10.1190/1.1443194.

Testo completo

Abstract (sommario):

A new method for dielectric constant and conductivity inversion is described in this article. The method consists of a two‐step process. A mathematical operation named the ‘Pinched Second Derivative” is first defined and applied to identify the bed boundaries of a multilayered medium. The operation is based on the fact that when a receiver crosses a bed boundary, the received signal suffers a discontinuity in the second derivative in proportion to the dielectric contrast between the adjacent beds. An oscillating multilayer forward model is then used to parametrically invert the dielectric constant and conductivity of each layer of the medium. The inversion involves a two‐dimensional (2-D)‐moving‐grid search and an error function defined through a Chebyshev type metric.

Gli stili APA, Harvard, Vancouver, ISO e altri

Xavier, Marcel, e Nicolas Van Goethem. "Brittle fracture on plates governed by topological derivatives". Engineering Computations 39, n. 1 (30 settembre 2021): 421–37. http://dx.doi.org/10.1108/ec-07-2021-0375.

Testo completo

Abstract (sommario):

PurposeIn the paper an approach for crack nucleation and propagation phenomena in brittle plate structures is presented.Design/methodology/approachThe Francfort–Marigo damage theory is adapted to the Kirchhoff and Reissner–Mindlin plate bending models. Then, the topological derivative method is used to minimize the associated Francfort–Marigo shape functional. In particular, the whole damaging process is governed by a threshold approach based on the topological derivative field, leading to a notable simple algorithm.FindingsNumerical simulations are driven in order to verify the applicability of the proposed method in the context of brittle fracture modeling on plates. The obtained results reveal the capability of the method to determine nucleation and propagation including bifurcation of multiple cracks with a minimal number of user-defined algorithmic parameters.Originality/valueThis is the first work concerning brittle fracture modeling of plate structures based on the topological derivative method.

Gli stili APA, Harvard, Vancouver, ISO e altri

Izgec, B., e C. S. S. Kabir. "Identification and Characterization of High-Conductive Layers in Waterfloods". SPE Reservoir Evaluation & Engineering 14, n. 01 (20 dicembre 2010): 113–19. http://dx.doi.org/10.2118/123930-pa.

Testo completo

Abstract (sommario):

Summary This study expands upon the use of modified-Hall analysis (MHA) to discern the characteristics of a high-permeability channel. Briefly, the modified-Hall plot uses three curves involving improved Hall-integral (H-I) and the two derivatives, analytic and numeric. Ordinarily, the derivative curves overlay on the integral curve during matrix injection, but separate lower when fracturing occurs. This work presents a method to identify and characterize high-conductive layers or channels between injector and producer pairs with the MHA. The distance separating the integral and derivative curves provides the required information to quantify channel properties. A simple analytical solution is presented for transforming the separation distance into channel permeabilitythickness product. The analytic derivative is based on the radial-flow-pattern assumption and the numeric derivative is correlated to the pressure response. Therefore, a comparison of these two curves reveals clues about the maturity of a waterflood at a given time. Several simulated examples verified the channel-property-estimation algorithm and identified the distinctive derivative signatures for channeling and fracturing situations. This method is also useful for identification of wormhole propagation during sand production in unconsolidated formations.

Gli stili APA, Harvard, Vancouver, ISO e altri

Più fonti

Tesi sul tema "Derivative propagation method"

Lods, Guillaume. "Modélisation et utilisation de la compliance des robots continus : application aux robots à tubes concentriques". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAD045.

Testo completo

Abstract (sommario):

Initialement développés pour automatiser les industries manufacturières, les robots sont désormais utilisés pour réaliser des interventions chirurgicales. Avec la volonté de minimiser le traumatisme des patients, les robots continus, flexibles et hautement miniaturisables, sont devenus un sujet de recherche très actif. La plupart des algo- rithmes de commande de ces robots utilisent des modèles analytiques construits à partir de la théorie de Cosserat. Cette thèse reconsidère le concept de compliance des robots continus en proposant une nouvelle définition : la matrice de compliance généralisée. Cette dernière est calculée grâce à une méthode littérale dite de "pro- pagation de dérivées bas-niveau", spécialement conçue pour permettre un calcul rapide. Ce concept de compliance généralisée est ensuite utilisé pour estimer les efforts d’interaction entre le robot et son environnement, élément indispensable pour garantir la sûreté de l’intervention. Tout au long de cette thèse, les contributions dévelop- pées pour les robots continus sont systématiquement appliquées au cas particulier des robots à tubes concentriques, à travers des simulations et des essais expérimentaux
First developed to automate production in manufacturing industries, robots are now used to assist surgical procedures. Flexible and highly miniaturizable continuum robots, allowing for the reduction of patient trauma, have raised significant interest in this field. Their study has then become an active research field. Most control algorithms developed for these robots are based on literal models derived from the Cosserat theory. This thesis reconsiders the concept of compliance for continuum robots by introducing the concept of generalized compliance matrix. This matrix is computed using a “low-level derivative propagation method” specifically designed for efficient computation. This concept of generalized compliance is then applied to estimate the interaction forces between the robot and its environment, a crucial issue for guaranteeing safe interventions. In this thesis, the contributions described for continuum robots are systematically transferred to the concentric tubes robots through simulations and experimental studies

Gli stili APA, Harvard, Vancouver, ISO e altri

Blanc, Emilie. "Time-domain numerical modeling of poroelastic waves : the Biot-JKD model with fractional derivatives". Phd thesis, Aix-Marseille Université, 2013. http://tel.archives-ouvertes.fr/tel-00954506.

Testo completo

Abstract (sommario):

Une modélisation numérique des ondes poroélastiques, décrites par le modèle de Biot, est proposée dans le domaine temporel. La dissipation visqueuse à l'intérieur des pores est décrite par le modèle de perméabilité dynamique, développé par Johnson-Koplik-Dashen (JKD). Certains coefficients du modèle de Biot-JKD sont proportionnels à la racine carrée de la fréquence : dans le domaine temporel, ces coefficients introduisent des dérivées fractionnaires décalées d'ordre 1/2, qui reviennent à un produit de convolution. Basé sur une représentation diffusive, le produit de convolution est remplacé par un nombre fini de variables de mémoire, dont la relaxation est gouvernée par une équation différentielle ordinaire locale en temps, ce qui mène au modèle de Biot-DA (approximation diffusive). Les propriétés du modèle de Biot-JKD et du modèle de Biot-DA sont analysées : hyperbolicité, décroissance de l'énergie, dispersion. Pour déterminer les coefficients de l'approximation diffusive, différentes méthodes de quadrature sont proposées : quadratures de Gauss, procédures d'optimisation linéaire ou non-linéaire sur la plage de fréquence d'intérêt. On montre que l'optimisation non-linéaire est la meilleure méthode de détermination. Le système est modélisé numériquement en utilisant une méthode de splitting : la partie propagative est discrétisée par un schéma aux différences finies ADER, d'ordre 4 en espace et en temps, et la partie diffusive est intégrée exactement. Une méthode d'interface immergée est implémentée pour discrétiser la géometrie sur une grille cartésienne et pour discrétiser les conditions de saut aux interfaces. Des simulations numériques sont présentées, pour des milieux isotropes et isotropes transverses. Des comparaisons avec des solutions analytiques montrent l'efficacité et la précision de cette approche. Des simulations numériques en milieux complexes sont réalisées : influence de la porosité d'os spongieux, diffusion multiple en milieu aléatoire.

Gli stili APA, Harvard, Vancouver, ISO e altri

Capitoli di libri sul tema "Derivative propagation method"

Lie, Khun-Hong, Henry C. Y. Chung e Kuldip S. Sidhu. "Derivation, Propagation, and Characterization of Neuroprogenitors from Pluripotent Stem Cells (hESCs and hiPSCs)". In Methods in Molecular Biology, 237–46. Totowa, NJ: Humana Press, 2012. http://dx.doi.org/10.1007/978-1-61779-794-1_15.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Baharvand, Hossein, Mehdi Totonchi, Adeleh Taei, Ali Seifinejad, Nasser Aghdami e Ghasem Hosseini Salekdeh. "Human-Induced Pluripotent Stem Cells: Derivation, Propagation, and Freezing in Serum- and Feeder Layer-Free Culture Conditions". In Methods in Molecular Biology, 425–43. Totowa, NJ: Humana Press, 2009. http://dx.doi.org/10.1007/978-1-60761-369-5_23.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Chen, Quan, Jiangtao Wang, Ruiqiu Ou e Sang-Bing Tsai. "An Empirical Study on the Network Model and the Online Knowledge Production Structure". In Research Anthology on Agile Software, Software Development, and Testing, 599–611. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-3702-5.ch030.

Testo completo

Abstract (sommario):

Mass production has attracted much attention as a new approach to knowledge production. The R software system is a typical product of mass production. For its unique architecture, the R software system accurately recorded the natural process of knowledge propagation and inheritance. Thus, this article established a dynamic complex network model based on the derivative relationship between R software packages, which reflects the evolution process of online knowledge production structure in R software system, and studied the process of knowledge propagation and inheritance via the dynamic complex network analysis method. These results show that the network size increases with time, reflecting the tendency of R software to accelerate the accumulation of knowledge. The network density and network cohesion decrease with the increase of scale, indicating that the knowledge structure of R software presents a trend of expansion. The unique extension structure of R software provides a rich research foundation for the propagation of knowledge; thus, the results can provide us a new perspective for knowledge discovery and technological innovation.

Gli stili APA, Harvard, Vancouver, ISO e altri

Pinheiro de Moura, José, e João Viana da Fonseca Neto. "Adjustment of the PID Gains Vector Due to Parametric Variations in the Plant Model in Terms of Internal Product". In Control Based on PID Framework - The Mutual Promotion of Control and Identification for Complex Systems. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95051.

Testo completo

Abstract (sommario):

The tuning of the gains of a controller with proportional-integral-derivative (PID) actions has been prevalent in the industry. The adjustment of these gains in PID controllers is often determined by classical methods, such as Ziegler-Nichols, and trial and error. However, these methods fail to deliver satisfactory performance and often do not meet specific project demands because of the inherent complexity of industrial processes, such as plant parameter variations. To solve the tuning problem in highly complex industrial processes, a controller adjustment method based on the internal product of PID terms is proposed, and a propagation matrix (PM) is generated by the numerator coefficients of the plant transfer function (TF). In the proposed method, each term of the PID controller is influenced by each of the numerator and the denominator coefficients. Mathematical models of practical plants, such as unloading and resumption of bulk solids by car dumpers and bucket wheel resumption, were employed to evaluate the proposed method. The obtained results demonstrated an assertive improvement in the adjustment gains from PID actions, thereby validating it as a promising alternative to conventional methods.

Gli stili APA, Harvard, Vancouver, ISO e altri

Xie, Ke-Jun, Robert D. Ciskowski e Larry H. Royster. "An Investigation of Wave Propagation in Viscoelastic Media Modeled by Fractional Derivative Using the Boundary Element Method". In Boundary Element Methods in Applied Mechanics, 523–31. Elsevier, 1988. http://dx.doi.org/10.1016/b978-0-08-036958-7.50056-0.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

"Appendix A Finite Difference Approximations of Derivatives". In Beam Propagation Method for Design of Optical Waveguide Devices, 300–303. Chichester, UK: John Wiley & Sons, Ltd, 2015. http://dx.doi.org/10.1002/9781119083405.app1.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Hasegawa, Akira, e Yuji Kodama. "Derivation Of The Wave Packet Equation And Introduction To Soliton Transmission Systems". In Solitons in Optical Communications, 17–44. Oxford University PressOxford, 1995. http://dx.doi.org/10.1093/oso/9780198565079.003.0003.

Testo completo

Abstract (sommario):

Abstract In this chapter, we derive the nonlinear envelope equation describing the linear and the nonlinear dispersion as well as dissipation effects from the Maxwell equation and the property of dielectric polarizability for the electric field wave propagation in a fibre. The method used here is based on an asymptotic perturbation technique developed by Taniuti et al. (the so-called reductive perturbation method (Taniuti 1974)), and the result gives a consistent scheme for the derivation of the wave envelope equation in the form of the nonlinear Schrodinger equation including higher order terms.

Gli stili APA, Harvard, Vancouver, ISO e altri

Hayati Raad, Shiva, e Zahra Atlasbaf. "Dyadic Green’s Function for Multilayered Planar, Cylindrical, and Spherical Structures with Impedance Boundary Condition". In Electromagnetic Wave Propagation for Industry and Biomedical Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.95834.

Testo completo

Abstract (sommario):

The integral equation (IE) method is one of the efficient approaches for solving electromagnetic problems, where dyadic Green’s function (DGF) plays an important role as the Kernel of the integrals. In general, a layered medium with planar, cylindrical, or spherical geometry can be used to model different biomedical media such as human skin, body, or head. Therefore, in this chapter, different approaches for the derivation of Green’s function for these structures will be introduced. Due to the recent great interest in two-dimensional (2D) materials, the chapter will also discuss the generalization of the technique to the same structures with interfaces made of isotropic and anisotropic surface impedances. To this end, general formulas for the dyadic Green’s function of the aforementioned structures are extracted based on the scattering superposition method by considering field and source points in the arbitrary locations. Apparently, by setting the surface conductivity of the interfaces equal to zero, the formulations will turn into the associated problem with dielectric boundaries. This section will also aid in the design of various biomedical devices such as sensors, cloaks, and spectrometers, with improved functionality. Finally, the Purcell factor of a dipole emitter in the presence of the layered structures will be discussed as another biomedical application of the formulation.

Gli stili APA, Harvard, Vancouver, ISO e altri

Ammari, Habib, Elie Bretin, Josselin Garnier, Hyeonbae Kang, Hyundae Lee e Abdul Wahab. "Topological Derivative Based Imaging of Small Inclusions in the Time-Harmonic Regime". In Mathematical Methods in Elasticity Imaging. Princeton University Press, 2015. http://dx.doi.org/10.23943/princeton/9780691165318.003.0007.

Testo completo

Abstract (sommario):

This chapter introduces a topological derivative (TD) based imaging framework for detecting small inclusions in the time-harmonic regime. Based on a weighted Helmholtz decomposition of the TD based imaging functional, optimal resolution imaging is achieved. Its stability properties with respect to both medium and measurement noises are investigated. The chapter first considers the TD imaging functional resulting from the expansion of the filtered quadratic misfit with respect to the size of the inclusion. It shows that the imaging functional may not attain its maximum at the location of the inclusion. Moreover, the resolution of the image is below the diffraction limit. Both phenomena are due to the coupling of pressure and shear waves propagating with different wave speeds and polarization directions. The chapter concludes by presenting the sensitivity analysis of a modified imaging functional based on the weighted Helmholtz decomposition of the TD.

Gli stili APA, Harvard, Vancouver, ISO e altri

Pera, Martin F., Andrew Laslett, Susan M. Hawes, Irene Tellis, Karen Koh e Lihn Nguyen. "Isolation and characterization of human ES cells". In Embryonic Stem Cells, 238–59. Oxford University PressOxford, 2006. http://dx.doi.org/10.1093/oso/9780198550006.003.0010.

Testo completo

Abstract (sommario):

Abstract This chapter will describe methods for the isolation and characterization of human embryonic stem (hES) cell lines from preimplantation blastocysts. The first derivation of hES cells was reported in 1998 (1), and since that time a number of groups have successfully established other, similar cell lines with the key features of primate pluripotent stem cells (2). There have been some significant improvements to the original culture system for hES cell propagation, and some refinements in the methodology for characterization of the cells. However, the mechanisms that regulate hES cell proliferation and differentiation are still poorly understood; there are practical limitations to existing culture methodology; and detailed, multicentre comparisons to assess the properties of hES cell isolates derived under different conditions and from different laboratories have not yet been carried out. Thus, while the current methodology is certainly adequate to support derivation and expansion of hES cells, the techniques and approaches described herein are likely to undergo substantial modification in the next several years.

Gli stili APA, Harvard, Vancouver, ISO e altri

Atti di convegni sul tema "Derivative propagation method"

Green, Eric, e Andrew Ning. "Derivative Propagation Through Vortex Particle Method Simulation". In AIAA AVIATION FORUM AND ASCEND 2024. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2024. http://dx.doi.org/10.2514/6.2024-4295.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Zhang, Junjian, Guoyi Ke e Z. Charlie Zheng. "Time-Domain Simulation of Ultrasound Propagation With Fractional Laplacian". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65966.

Testo completo

Abstract (sommario):

The simulation is developed for the purpose of simulating ultrasound propagation through biological tissues. The simulation is based on the time-domain conservation laws with the governing equations for acoustic pressure and velocity, with frequency dependent absorption and dispersion effects. We use forward differencing for velocity and backward differencing for pressure on the non-fractional derivative operator terms in spatial discretization. The fractional Laplacian operators are treated as Riesz derivatives. The shifted standard Grunwald approximation method is used to solve fractional derivative operator terms. To accommodate complicated biological tissue geometries, an immersed boundary method is developed that enables a Cartesian computational grid mesh to be used. The results are compared with those for a non-absorption homogeneous medium to discuss absorption and dispersion effects of biological material.

Gli stili APA, Harvard, Vancouver, ISO e altri

Antonopoulos, Christos S., Nikolaos V. Kantartzis e Ioannis T. Rekanos. "FDTD method for wave propagation in Havriliak-Negami media based on fractional derivative approximation". In 2016 IEEE Conference on Electromagnetic Field Computation (CEFC). IEEE, 2016. http://dx.doi.org/10.1109/cefc.2016.7816182.

Testo completo

Gli stili APA, Harvard, Vancouver, ISO e altri

Thomas, Axel, Tom Druet, Arnaud Recoquillay e Bastien Chapuis. "Simulation-Assisted Guided Waves Imaging for SHM : Tomography and Shape Derivative". In 2024 51st Annual Review of Progress in Quantitative Nondestructive Evaluation. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/qnde2024-138487.

Testo completo

Abstract (sommario):

Abstract The remaining thickness of a structure is critical information for many sensitive industries. To this end, Structural Health Monitoring (SHM) aims to establish regular monitoring of critical infrastructure. We are particularly interested here in tomographic methods using guided elastic waves. These methods can reconstruct the thickness of a structure from measurements of the guided wave propagation. Until now, the most studied guided waves tomographic method are based on an acoustic propagation model. Although it provides a quick and robust estimate of thickness, its resolution and applicability are limited due to simplified physics. To overcome this problem, we have adapted the so-called shape derivative to the elastodynamic case, which can be seen as a specific case of FullWaveformInversion where the shape of the structure is recovered. This iterative approach considers all the effects that occur during propagation, enabling the handling of complex structures. An optimized calculation is performed with the help of spectral finite element method. However, shape derivative method stay very time-consuming due to many iteration necessary for convergence. To address this issue, we have chosen to use the result of acoustic algorithm as an initial estimate. This strategy reduces computational times. This paper presents experimental case studies demonstrating the significance of initialization in the algorithm’s convergence process.

Gli stili APA, Harvard, Vancouver, ISO e altri

Okutucu, Tuba, e Yaman Yener. "Propagation of Ultra-Short-Pulse Radiation in Participating Media: A Laguerre-Galerkin Solution". In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41911.

Testo completo

Abstract (sommario):

Transient analysis of the radiative transfer problem in participating media has become essential due to the recent applications involving extremely small time scales. In classical radiation problems, the time derivative term in the radiative transfer equation has a negligible order of magnitude compared to the others. Lasers of pico- to femtosecond pulse durations are now being used to investigate the properties of scattering and absorbing media in such applications as, optical tomography, combustion product analysis, and remote sensing. For such applications, the time derivative in the radiative transfer equation can no longer be neglected. Numerous approaches such as, integral formulation, direct numerical approach, discrete ordinates method, Monte Carlo simulations, and Galerkin technique have been introduced for the solution of transient radiative transfer problems in participating media. In the present work, Laguerre-Galerkin solutions for both rectangular and Gaussian incident pulse profiles are presented.

Gli stili APA, Harvard, Vancouver, ISO e altri

Hanssen, Finn-Christian W., Jens B. Helmers e Marilena Greco. "A Coupled Harmonic Polynomial Cell and Higher-Order Spectral Method for Nonlinear Wave Propagation". In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-19305.

Testo completo

Abstract (sommario):

Abstract The present work deals with wave generation in fully nonlinear numerical wave tanks (NWT). As an alternative to modelling a moving (physical) wavemaker, a two-dimensional (2D) potential-flow NWT is coupled with an external spectral wave data (SWD) application programming interface (API). The NWT uses the harmonic polynomial cell (HPC) method to solve the governing Laplace equations for the velocity potential and its time derivative, and has previously been extensively validated and verified for numerous nonlinear wave-propagation problems using traditional wave-generation mechanisms. Periodic waves of different steepness generated with a stream-function theory as reference solution in the SWD API are first considered to investigate the method’s numerical accuracy. Thereafter, with a higher-order spectral method (HOSM) as the SWD API solution, irregular waves with different wave heights and water depths relevant for e.g. aquaculture and offshore structures are simulated. Differences between the HPC and HOSM solutions in and near steep crests are investigated. The study aims to demonstrate a robust method to generate and propagate general wave fields for further studies of nonlinear waves and wave-body interaction in both two and three dimensions.

Gli stili APA, Harvard, Vancouver, ISO e altri

Yi, Yang, Wang Zhan, Longlei Dong e Guirong Yan. "An Iterative Circular Contour Winding Number Integral Method and its Application in Wave Propagation Analysis of Infinite Fluid-Filled Cylinder". In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-85561.

Testo completo

Abstract (sommario):

In this article, an iterative circular contour winding number integral method (ICCWNI) is proposed. The error analysis and convergence proof is given. It overcomes the fault that the traditional circular winding number integral method can not locate the zeros accurately for the complex equation including function items of large-value derivative. In order to verify its reliability, the dispersion curves of infinite fluid-filled and fluid-loaded cylinder are computed. The results are in accord with the ones in the previous literatures.

Gli stili APA, Harvard, Vancouver, ISO e altri

Zhangli, Wang, Hu Benxue, Wang Guodong, Wang Zhe, Ni Chenxiao e Liu Xin. "Studies on Sensitivity and Uncertainty Analyses for SCOPE and WAFT With Uncertainty Propagation Methods". In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66985.

Testo completo

Abstract (sommario):

The purpose of Steam condensation on cold plate experiment facility (SCOPE) and Water film test (WAFT) is to verify the steam condensation and water film evaporation correlation within the parameter variation range of CAP1400 passive containment cooling system. These correlations were used for containment response analysis. Uncertainty and sensitivity analyses were performed for SCOPE and WAFT tests in this paper. Sampling-based sensitivity analysis with uncertainty propagation is a new parameters sensitivity analysis method, and the importance of input parameters could be evaluated by calculating the correlation coefficients between input parameters and the output target parameter. This method was used to acquire the influence of the measured input parameters uncertainty on the output target parameter. The results show that air and steam flow rate, coolant flow rate, inlet and outlet water temperature are the main source of the uncertainty for SCOPE. Inlet film flow rate, inlet air flow velocity and plate surface temperatures are the main source of the uncertainty for WAFT. Sensitivity analysis results may provide support for experiment measurement system optimization to reduce the target parameter error range. Uncertainty analysis is one important aspect of test data analyses, which is meaningful to the assessment of test results. Conventionally the partial derivative with respect to the input parameters is used to transfer uncertainty from the input parameters to the output parameter. However, in this method the partial derivatives of the output parameter sub the input parameters must be calculated. For complex engineering problems, it is usually difficult to acquire theoretical correlations for the partial derivatives. WILKs formula is used to determine the parameter tolerance interval with certain probability content and confidence level. The tolerance interval is a good way to well describe the uncertainty of parameters. The nonparametric statistics with WILKS correlation were widely used in the best-estimate plus uncertainty (BEPU) accident analyses. However, little work has been conducted on the experiment results uncertainty analysis with that method. In this paper nonparametric statistics with WILKS correlation was used to acquire key parameters uncertainty. And the results show that key output parameters uncertainty for SCOPE and WAFT are within the reasonable range. Uncertainty Propagation Methods were implied for test results Sensitivity and Uncertainty Analysis in the paper, which may be conveniently applied to the other experiment data analyses and also valuable to the engineering project.

Gli stili APA, Harvard, Vancouver, ISO e altri

Wei, Wang, Yang Kaiming, Zhu Yu, Qian Yuyang, Wan Chenhui e Li Min. "Walking Speed Estimation From a Wearable Insole Pressure System Using a Bayesian Regularized Back Propagation Neural Network". In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23363.

Testo completo

Abstract (sommario):

Abstract In this study, we introduced a machine learning method for estimating human walking speed using plantar pressure and acceleration data. A pressure-derivative based with pretest feature selection method was proposed to extracted speed-related features from plantar pressure sensors. The maximum, minimum and standard deviation of acceleration data were also selected as neural network inputs. To improve the generalization ability of the neural network, a Bayesian regularization method was adopted. To validate the performance of the proposed method, experiments were conducted under seven different walking speeds. The results show that a strong linear correlation (R = 0.995) exists between the estimated and the actual walking speeds. The average error of the proposed method is 0.003 ± 0.043 m/s (mean ± root mean square error), which is better than previous works. The desirable performance of the proposed method proves that including the speed-related information of both stance and swing phase is beneficial for improving the accuracy of walking speed estimation.

Gli stili APA, Harvard, Vancouver, ISO e altri

Ibrahim, Ahmed Farid, Mazher Ibrahim, Matt Sinkey, Thomas Johnston e Wes Johnson. "Unique Fall Off Signatures for Stage Fracture Characterization, Actual Field Cases". In SPE Western Regional Meeting. SPE, 2021. http://dx.doi.org/10.2118/200887-ms.

Testo completo

Abstract (sommario):

Abstract Multistage hydraulic fracturing is the common stimulation technique for shale formations. The treatment design, formation in-situ stress, and reservoir heterogeneity govern the fracture network propagation. Different techniques have been used to evaluate the fracture geometry and the completion efficiency including Chemical Tracers, Microseismic, Fiber Optics, and Production Logs. Most of these methods are post-fracture as well as time and cost intensive processes. The current study presents the use of fall-off data during and after stage fracturing to characterize producing surface area, permeability, and fracture conductivity. Shut-in data (15-30 minutes) was collected after each stage was completed. The fall-off data was processed first to remove the noise and water hammer effects. Log-Log derivative diagnostic plots were used to define the flow regime and the data were then matched with an analytical model to calculate producing surface area, permeability, and fracture conductivity. Diagnostic plots showed a unique signature of flow regimes. A long period of a spherical flow regime with negative half-slope was observed as an indication for limited entry flow either vertically or horizontally. A positive half-slope derivative represents a linear flow regime in an infinitely conductive tensile fracture. The quarter-slope derivative was observed in a bilinear flow regime that represents a finite conductivity fracture system. An extended radial flow regime was observed with zero slope derivative which represents a highly shear fractured network around the wellbore. For a long fall-off period, formation recharge may appear with a slope between unit and 1.5 slopes derivative, especially in over-pressured dry gas reservoirs. Analyzing fall-off data after stages are completed provides a free and real-time investigation method to estimate the fracture geometry and a measure of completion efficiency. Knowing the stage properties allows the reservoir engineer to build a simulation model to forecast the well performance and improve the well spacing.

Gli stili APA, Harvard, Vancouver, ISO e altri

Rapporti di organizzazioni sul tema "Derivative propagation method"

Hart, Carl, Gregory Lyons e Michael White. Spherical shock waveform reconstruction by heterodyne interferometry. Engineer Research and Development Center (U.S.), maggio 2024. http://dx.doi.org/10.21079/11681/48471.

Testo completo

Abstract (sommario):

The indirect measurement of shock waveforms by acousto-optic sensing requires a method to reconstruct the field from the projected data. Under the assumption of spherical symmetry, one approach is to reconstruct the field by the Abel inversion integral transform. When the acousto-optic sensing modality measures the change in optical phase difference time derivative, as for a heterodyne Mach–Zehnder interferometer, e.g., a laser Doppler vibrometer, the reconstructed field is the fluctuating refractive index time derivative. A technique is derived that reconstructs the fluctuating index directly by assuming plane wave propagation local to a probe beam. With synthetic data, this approach is compared to the Abel inversion integral transform and then applied to experimental data of laser-induced shockwaves. Time waveforms are reconstructed with greater accuracy except for the tail of the waveform that maps spatially to positions near a virtual origin. Furthermore, direct reconstruction of the fluctuating index field eliminates the required time integration and results in more accurate shock waveform peak values, rise times, and positive phase duration.

Gli stili APA, Harvard, Vancouver, ISO e altri

Offriamo sconti su tutti i piani premium per gli autori le cui opere sono incluse in raccolte letterarie tematiche. Contattaci per ottenere un codice promozionale unico!