Bibliografie tematiche / Two-Loop computation

Letteratura scientifica selezionata sul tema "Two-Loop computation"

Autore: Grafiati

Pubblicato: 22 giugno 2024

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Articoli di riviste sul tema "Two-Loop computation":

Yuasa, F., E. de Doncker, N. Hamaguchi, T. Ishikawa, K. Kato, Y. Kurihara, J. Fujimoto e Y. Shimizu. "Numerical computation of two-loop box diagrams with masses". Computer Physics Communications 183, n. 10 (ottobre 2012): 2136–44. http://dx.doi.org/10.1016/j.cpc.2012.05.018.

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Pesando, I. "Polymers and topological field theory. A two-loop computation". Physics Letters B 296, n. 3-4 (dicembre 1992): 341–52. http://dx.doi.org/10.1016/0370-2693(92)91330-c.

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Xu, Dan, Yanfeng Li, Anguo Dai, Shumei Zhao e Weitang Song. "Closed-Loop Optimal Control of Greenhouse Cultivation Based on Two-Time-Scale Decomposition: A Simulation Study in Lhasa". Agronomy 13, n. 1 (28 dicembre 2022): 102. http://dx.doi.org/10.3390/agronomy13010102.

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Due to the heavy computation load of closed-loop simulations, optimal control of greenhouse climate is usually simulated in an open-loop form to produce control strategies and profit indicators. Open-loop simulations assume the model, measurements, and predictions to be perfect, resulting in too-idealistic indicators. The method of two-time-scale decomposition reduces the computation load, thus facilitating the online implementation of optimal control algorithms. However, the computation time of nonlinear dynamic programming is seldom considered in closed-loop simulations. This paper develops a two-time-scale decomposed closed-loop optimal control algorithm that involves the computation time. The obtained simulation results are closer to reality since it considers the time delay in the implementation. With this algorithm, optimal control of Venlo greenhouse lettuce cultivation is investigated in Lhasa. Results show that compared with open-loop simulations, the corrections in yield and profit indicators can be up to 2.38 kg m−2 and 11.01 CNY m−2, respectively, through closed-loop simulations without considering the computation time. When involving the time delay caused by the computation time, further corrections in yield and profit indicators can be up to 0.1 kg m−2 and 0.87 CNY m−2, respectively. These conservative indicators help investors make wiser decisions before cultivation. Moreover, control inputs and greenhouse climate states are within their bounds most of the time during closed-loop simulations. This verifies that the developed algorithm can be implemented in real time.

FUJIMOTO, Junpei, Yoshimitsu SHIMIZU, Kiyoshi KATO e Toshiaki KANEKO. "NUMERICAL APPROACH TO TWO-LOOP THREE POINT FUNCTIONS WITH MASSES". International Journal of Modern Physics C 06, n. 04 (agosto 1995): 525–30. http://dx.doi.org/10.1142/s0129183195000381.

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Extending the method successful for one-loop integrals, the computation of two-loop diagrams with general internal masses is discussed. For the two-loop vertex of nonplanar type, as an example, we show a calculation related to [Formula: see text] vertex.

Bode, Achim, Peter Weisz e Ulli Wolff. "Two-loop computation of the Schrödinger functional in lattice QCD". Nuclear Physics B 576, n. 1-3 (giugno 2000): 517–39. http://dx.doi.org/10.1016/s0550-3213(00)00187-5.

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Tarasov, O. V. "Computation of Gröbner bases for two-loop propagator type integrals". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 534, n. 1-2 (novembre 2004): 293–98. http://dx.doi.org/10.1016/j.nima.2004.07.104.

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Su, Huayou, Kaifang Zhang e Songzhu Mei. "On the Transformation Optimization for Stencil Computation". Electronics 11, n. 1 (23 dicembre 2021): 38. http://dx.doi.org/10.3390/electronics11010038.

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Stencil computation optimizations have been investigated quite a lot, and various approaches have been proposed. Loop transformation is a vital kind of optimization in modern production compilers and has proved successful employment within compilers. In this paper, we combine the two aspects to study the potential benefits some common transformation recipes may have for stencils. The recipes consist of loop unrolling, loop fusion, address precalculation, redundancy elimination, instruction reordering, load balance, and a forward and backward update algorithm named semi-stencil. Experimental evaluations of diverse stencil kernels, including 1D, 2D, and 3D computation patterns, on two typical ARM and Intel platforms, demonstrate the respective effects of the transformation recipes. An average speedup of 1.65× is obtained, and the best is 1.88× for the single transformation recipes we analyze. The compound recipes demonstrate a maximum speedup of 1.92×.

Capitani, Stefano, Sergio Caracciolo, Andrea Pelissetto e Giancarlo Rossi. "High-precision computation of two-loop Feynman diagrams with Wilson fermions". Nuclear Physics B - Proceedings Supplements 63, n. 1-3 (aprile 1998): 802–4. http://dx.doi.org/10.1016/s0920-5632(97)00905-5.

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Niskanen, A. O., M. Nakahara e M. M. Salomaa. "Optimal holonomic quantum gates". Quantum Information and Computation 2, Special (novembre 2002): 560–77. http://dx.doi.org/10.26421/qic2.s-6.

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We study the construction of holonomy loops numerically in a realization-independent model of holonomic quantum computation. The aim is twofold. First, we present our technique of finding the suitable loop in the control manifold for any one-qubit and two-qubit unitary gates. Second, we develop the formalism further and add a penalty term for the length of the loop, thereby aiming to minimize the execution time for the quantum computation. Our method provides a general means by which holonomy loops can be realized in an experimental setup. Since holonomic quantum computation is adiabatic, optimizing with respect to the length of the loop may prove crucial.

Chetyrkin, K. G., R. Harlander, J. H. Kühn e M. Steinhauser. "Automatic computation of three-loop two-point functions in large momentum expansion". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 389, n. 1-2 (aprile 1997): 354–56. http://dx.doi.org/10.1016/s0168-9002(97)00128-9.

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Più fonti

Tesi sul tema "Two-Loop computation":

Barrios, Nahuel. "Yang-Mills and Quantum Chromodynamics correlation functions from the Curci-Ferrari model at two-loop accuracy". Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAX081.

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La Chromodynamique Quantique (QCD) est une théorie de jauge bien établie qui décrit la dynamique des quarks et des gluons. Au niveau analytique, les observables physiques ne peuvent être calculées que lorsque la jauge est fixée. La méthode standard pour y parvenir est la méthode de Faddeev-Popov (FP), qui introduit comme sous-produit des champs auxiliaires non physiques, les "fantômes". D'autre part, le couplage de jauge de la QCD devient faible pour des impulsions très élevées, ce qui fait de la théorie des perturbations (TP) un outil de calcul approprié dans cette limite. L'approche perturbative dans le cadre de la méthode de FP s'est avérée extrêmement utile et a été testée expérimentalement à de nombreuses reprises. Cependant, dans la gamme opposée d'impulsions, la méthode de FP n'est plus entièrement valide en raison de la présence de copies de Gribov. Par conséquent, pour accéder à l'infrarouge de la QCD, une approche alternative est nécessaire.Cette thèse est consacrée à une de ces approches : le modèle de Curci-Ferrari (CF) dans la jauge de Landau. Elle consiste en une simple extension de la théorie de FP, à laquelle est ajouté un terme de masse pour le champ de gluons. Sa principale motivation provient des simulations numériques de fonctions de corrélation dans la jauge de Landau, qui indiquent clairement que le gluon acquiert une masse dans l'infrarouge profond. En plus de ce phénomène frappant, les simulations numériques montrent un couplage de jauge compatible avec une analyse perturbative pour toute la gamme d'impulsions, au moins pour le secteur pure jauge - ou de Yang-Mills (YM). Ainsi, afin de tester le modèle, plusieurs fonctions de corrélation à deux et trois points ont été évaluées de manière perturbative à une boucle. D'une manière générale, ces résultats montrent un bon accord avec leurs homologues numériques. Plus récemment, les fonctions à deux points de la théorie YM pure ont été évaluées à deux boucles, améliorant ainsi l'accord avec les données des simulations. L'objectif de cette thèse est d'étendre les calculs à deux boucles à d'autres fonctions de corrélation. Il s'agira ainsi de tester plus avant l'approche perturbative dans le modèle de CF, tout en clarifiant ses limites.Dans le cas de la théorie YM pure, nous évaluons le vertex fantôme-antifantôme-gluon et le vertex à trois gluons dans une configuration cinématique particulière, en quatre dimensions, pour les groupes de jauge SU(2) et SU(3). Ces deux quantités sont une pure prédiction du modèle de CF, puisque les deux paramètres libres du modèle sont déterminés à partir de l'ajustement des fonctions à deux points. De manière générale, les corrections à deux boucles améliorent l'accord avec les numériques par rapport aux corrections à une boucle. La dépendance de nos prédictions par rapport au schéma de renormalisation, diminue également une fois les corrections à deux boucles incluses, ce qui conforte l'approche perturbative. En ce qui concerne le vertex à trois gluons, le calcul nous permet notamment d'obtenir des informations sur le passage à zéro ainsi que de tester une prédiction sur le comportement dominant exact de cette quantité dans l'infrarouge.Nous concluons cette étude en calculant les fonctions à deux boucles pour le fantôme, le gluon et le quark dans le cadre de la QCD, en présence de deux saveurs dégénérées de quarks, et en les comparant aux données des simulations numériques. Les résultats à deux boucles montrent un accord au résultats numériques systématiquement meilleur par rapport aux évaluations à une boucle, à l'exception de la fonction de masse des quarks légers. Ce résultat est particulièrement pertinent pour la fonction d'habillage des quarks, puisque les calculs à une boucle est incapable de reproduire les données des simulations. Cette incohérence est levée à deux boucles tant sur le plan qualitatif que quantitatif
Quantum Chromodynamics (QCD) is a well established gauge theory which describes the dynamics of quarks and gluons. At the analytical level, physical observables can be computed only after the gauge is fixed. The textbook procedure to do so is the Faddeev-Popov (FP) method, which introduces, as a byproduct, auxiliary non-physical fields known as ghosts. Moreover, the QCD gauge coupling becomes small at very high momenta, making of perturbation theory (PT) a suitable calculation tool within that region of momenta. The combination of the FP theory and PT has turned out to be extremely useful and has been tested experimentally in many occasions. However, in the opposite momentum range, the FP method is no longer fully valid due to the presence of Gribov copies. Consequently, in order to access QCD in the infrared, new approaches are needed.This thesis is devoted to one of such approaches: the Curci-Ferrari (CF) model in Landau gauge. It consists in a simple gluon mass extension of the FP theory. Its main motivation comes from the lattice simulations for correlation functions in the Landau gauge, which clearly indicate that the gluon acquire a mass in the deep infrared. In addition to this striking phenomenon, the lattice simulations feature a gauge coupling compatible with a perturbative analysis for the whole range of momenta, at least in the pure gauge - or Yang-Mills (YM) - sector. Thus, with the purpose of testing the model, several two- and three-point correlation functions have been perturbatively evaluated at one-loop order. In general terms, the results show a very good agreement with the lattice data. More recently, the two-point functions from the pure YM theory were evaluated at two-loop order, improving the agreement to lattice data. The goal of this thesis is to extend the two-loop calculations to other correlation functions. This is a way of further testing the perturbative use of the model as well as to clarify its limits.In the case of pure YM theory, we evaluate the ghost-antighost-gluon vertex and the three-gluon vertex in a particular kinematical configuration in four dimensions, for the SU(2) and SU(3) gauge groups. Both quantities emerge as a pure prediction of the CF model, since its two free parameters are determined by fitting the two-point functions. Broadly speaking, the predicted vertices are able to improve the agreement with their numerical counterparts in comparison with the one-loop correction. We also investigate the renormalization scheme dependence of our results, which shows consistency with the perturbative approach. As for the three-gluon vertex, the calculation allows us in particular to gain insight on the zero-crossing as well as to test an exact prediction for the leading behavior in the infrared.We end this investigation by computing the ghost, gluon and quark two-point functions in QCD, with two degenerate quark flavors. We fit them to available lattice data. Our evaluation is consistent with such data in all the cases, except for the quark mass function for light quarks. The result is particularly relevant for the quark dressing function, since the CF model is unable to reproduce the lattice data at one-loop order. This discrepancy is corrected by the two-loop evaluation, which agrees with the data both at a qualitative and quantitative level

Capitoli di libri sul tema "Two-Loop computation":

Misra, Sanjay, Abraham Ayegba Alfa, Sunday Olamide Adewale, Michael Abogunde Akogbe e Mikail Olayemi Olaniyi. "A Two-Way Loop Algorithm for Exploiting Instruction-Level Parallelism in Memory System". In Computational Science and Its Applications – ICCSA 2014, 255–64. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-09156-3_19.

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Antonov, Nikolay V., e Nikolay M. Gulitskiy. "Two-Loop Calculation of the Anomalous Exponents in the Kazantsev-Kraichnan Model of Magnetic Hydrodynamics". In Mathematical Modeling and Computational Science, 128–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-28212-6_11.

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Çelik, Candan, Pavol Bokes e Abhyudai Singh. "Protein Noise and Distribution in a Two-Stage Gene-Expression Model Extended by an mRNA Inactivation Loop". In Computational Methods in Systems Biology, 215–29. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-85633-5_13.

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Melnyk, Virginia Ellyn. "Customized Knit Membrane Deployable Hyperboloid Tower". In Computational Design and Robotic Fabrication, 433–42. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8405-3_36.

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AbstractDeployable structures have become increasingly popular due to their ability to transform from a compact form into a larger structure. They are also typically lightweight, resulting in a lower carbon footprint than heavy permanent building methods. These structures are popular within the field of architecture, as well as in robotics, aerospace engineering, and other fields.This paper explores the design and development of a deployable hyperboloid structure with a connected knitted membrane. The knitted material is specifically designed to stretch and fit the transforming geometry of the hyperboloid. This is achieved by manipulating the types of yarn used across the membrane, as well as the number of short rows in the knit material, to create a more specified material. The design for this material was developed using Rhino3d and Grasshopper. Throughout the design and fabrication process, there was a feedback loop between the digital design models and physical material test samples to ensure that the knit would fit the final hyperboloid structure. The result is a two-meter-tall structure when upright and a two-meter-diameter circle when collapsed, with a knit membrane that supports the structure and transforms seamlessly by stretching and shrinking to the different shapes of transformation.

KAZAKOV, V. A., e I. K. KOSTOV. "COMPUTATION OF THE WILSON LOOP FUNCTIONAL IN TWO-DIMENSIONAL U(∞) LATTICE GAUGE THEORY". In The Large N Expansion in Quantum Field Theory and Statistical Physics, 239–42. WORLD SCIENTIFIC, 1993. http://dx.doi.org/10.1142/9789814365802_0017.

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Molnár, András J. "Modeling the Variety of Trip Opportunities in Recreational Route Networks". In Frontiers in Artificial Intelligence and Applications. IOS Press, 2022. http://dx.doi.org/10.3233/faia210491.

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In this paper, we deal with the question of how the variety of trip opportunities can be modeled in – possibly complex – recreational trail networks (such as hiking paths or cycling ways). In order to quantify the variety of possible loop trips starting from specific trailheads (starting nodes accessible from outside the network) and the variety of connecting trips between specific origin-destination pairs, two novel measures of Loop Trip Variety Index (LTVI) and Connecting Trip Variety Index (CTVI) are proposed preliminarily and informally in [12], respectively, in the frame of assessing the impacts of some recent trail network developments. This paper establishes the formal definitions of improved variants of these measures, shows their well-definedness, presents the algorithms of their computation, investigates on their properties and benefits, and gives reasons of how and to what extent they can be treated as models of trip variety. Possible uses, application areas and future improvements are sketched especially for visitor management planning and profile-based trip recommendation systems.

Raghavan, Gopalan. "Device Independence and the Quest towards Physical Limits of Privacy". In Topics on Quantum Information Science. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100364.

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There is a looming threat over current methods of data encryption through advances in quantum computation. Interestingly, this potential threat can be countered through the use of quantum resources such as coherent superposition, entanglement and inherent randomness. These, together with non-clonability of arbitrary quantum states, offer provably secure means of sharing encryption keys between two parties. This physically assured privacy is however provably secure only in theory but not in practice. Device independent approaches seek to provide physically assured privacy of devices of untrusted origin. The quest towards realization of such devices is predicated on conducting loop-hole-free Bell tests which require the use of certified quantum random number generators. The experimental apparatuses for conducting such tests themselves use non-ideal sources, detectors and optical components making such certification extremely difficult. This expository chapter presents a brief overview (not a review) of Device Independence and the conceptual and practical difficulties it entails.

Thomas, George, Timothy Wilmot, Steve Szatmary, Dan Simon e William Smith. "Evolutionary Optimization of Artificial Neural Networks for Prosthetic Knee Control". In Efficiency and Scalability Methods for Computational Intellect, 142–61. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-3942-3.ch007.

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This chapter discusses closed-loop control development and simulation results for a semi-active above-knee prosthesis. This closed-loop control is a delta control that is added to previously developed open-loop control. The control signal consists of two hydraulic valve settings. These valves control a rotary actuator that provides torque to the prosthetic knee. Closed-loop control using artificial neural networks (ANNs) are developed, which is an intelligent control method. The ANNs are trained with biogeography-based optimization (BBO), which is a recently developed evolutionary algorithm. This research contributes to the field of evolutionary algorithms by demonstrating that BBO is successful at finding optimal solutions to real-world, nonlinear, time varying control problems. The research contributes to the field of prosthetics by showing that it is possible to find effective closed-loop control signals for a newly proposed semi-active hydraulic knee prosthesis. The research also contributes to the field of ANNs; it shows that they are able to mitigate some of the effects of noise and disturbances that will be common in normal operation of a prosthesis and that they can provide better robustness and safer operation with less risk of stumbles and falls. It is demonstrated that ANNs are able to improve average performance over open-loop control by up to 8% and that they show the greatest improvement in performance when there is high risk of stumbles.

Angst, R., P. Mier e M. Kraume. "Simulations of the solid/liquid two-phase flow field in jet loop reactors". In Computational Fluid and Solid Mechanics, 1058–61. Elsevier, 2001. http://dx.doi.org/10.1016/b978-008043944-0/50840-4.

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Hogger, Christopher John. "Termination analysis". In Essentials of Logic Programming, 215–21. Oxford University PressOxford, 1990. http://dx.doi.org/10.1093/oso/9780198538202.003.0059.

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Abstract Termination analysis focuses on questions about the finiteness or otherwise of computations. There are a number of contexts in which analysis of this kind can be useful. Perhaps the most familiar of these is where a program interpreter is equipped with a loop-detector whose purpose is to recognize and/or bypass loops (infinite computations). We hinted at another use in the previous Theme, where loop-detection was implicit in a demonstration that a tree was infinitely failed and hence that two programs were computationally equivalent. Despite its obvious importance, termination analysis has for a long time been a relatively neglected subject amongst logic programming researchers, in contrast to the large body of knowledge about termination already developed for other programming formalisms. It is not clear why this is so, although it could be argued that the logic programmers have been preoccupied with supposedly more exciting issues. The last few years have nevertheless seen a considerable increase in interest, leading to a variety of proposed methods of analysis. It would, however, be premature here to attempt a state-of-the-art summary. In particular, the space available in this Theme permits only a brief excursion into the subject.

Atti di convegni sul tema "Two-Loop computation":

Papadopoulos, Costas, Adam Kardos, Alexander Smirnov, Nikolaos Syrrakos e Christopher Wever. "Progress in two-loop Master Integrals computation". In Loops and Legs in Quantum Field Theory. Trieste, Italy: Sissa Medialab, 2022. http://dx.doi.org/10.22323/1.416.0021.

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Zhu, Chuan-Jie. "Two-loop superstring: explicit computation, factorization, unitarity and beyond". In PARTICLES, STRINGS, AND COSMOLOGY: 11th International Symposium on Particles, Strings, and Cosmology; PASCOS 2005. AIP, 2005. http://dx.doi.org/10.1063/1.2149738.

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Mynderse, James A., e George T. C. Chiu. "Two Degree-of-Freedom Hysteresis Compensation for a Dynamic Mirror With Antagonistic Piezoelectric Stack Actuation". In ASME 2013 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/dscc2013-3869.

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A methodology for designing a low-computation, high-bandwidth strategy for closed-loop control of a hysteretic system without a priori knowledge of the desired trajectory is presented. The resulting two degree-of-freedom hysteresis control strategy is applied to a dynamic mirror with antagonistic piezoelectric stack actuation. Hysteresis compensator is performed by a finite state machine switching polynomials for hysteresis inversion based on the input signal slope. Residual error after hysteresis compensation is corrected by an LQR feedback controller. Experimental results demonstrate effectiveness of the hysteresis compensator and closed-loop system under the proposed hysteresis control strategy. For the triangular input signal tested, the closed-loop system achieves a 91.5% reduction in hysteresis uncertainty with 60 kHz sample rate.

Youn, Byeng D. "Integrated Framework for Design Optimization Under Aleatory and/or Epistemic Uncertainties Using Adaptive-Loop Method". In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-85253.

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In last two decades, significant attentions have been paid to develop design optimization methodologies under various uncertainties: reliability-based design optimization (RBDO), possibility-based design optimization (PBDO), etc. As a result, a variety of methods of uncertainty-based design optimization have been proposed and are mainly catagorized as: parallel-loop method, serial-loop method, and single-loop method. It has been reported that each method has its own strong and weak points. Thus, this paper attempts to understand various methods better, and proposes to develop an integrated framework for uncertainty-based design optimization. In short, the integrated design framework timely involves three phases (deterministic design optimization, parallel-loop method, single-loop method) to maximize numerical efficiency without losing computational stability and accuracy in the process of uncertainty-based design optimization. While the parallel-loop method maintains numerical stability well with a minimal computation, deterministic design optimization and single-loop method will improve numerical efficiency at the beginning and end of uncertainty-based design optimization. Thus, the proposed method is called adaptive-loop method. It will be shown that integrated framework using the proposed method is applicable for various design optimization methodologies under aleatory or epistemic uncertainties, such as RBDO, PBDO, etc. Examples are used to demonstrate the effectiveness of integrated framework using the adaptive-loop method in terms of numerical efficiency.

Ho, Y. H., e B. Lakshminarayana. "Computation of Unsteady Viscous Flow Through Turbomachinery Blade Row due to Upstream Rotor Wakes". In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-321.

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A time-accurate, two-dimensional, pressure-based, Navier-Stokes solver for incompressible flow is developed and used to carry out the numerical simulation of rotor-stator interaction. A low Reynolds number form of the two-equation turbulence model is used to account for the turbulence effects. In order to improve the accuracy of the numerical scheme, a central differencing plus an artificial dissipation scheme is implemented to provide precise control of numerical dissipation. An inner loop iteration scheme is used at each time step to account for the non-linear effects. The computation of unsteady flow through a flat plate cascade subjected to a transverse gust reveals that the choice of grid spacing and the amount of artificial dissipation is critical for accurate prediction of unsteady phenomena. The rotor-stator interaction problem is simulated by starting the computation upstream of the stator, and the upstream rotor wake is specified from the experimental data. The results show that the stator potential effects have appreciable influence on the upstream rotor wake. The predicted unsteady wake profiles are compared with the available experimental data and the agreement is good. The numerical results are interpreted to draw conclusions on the unsteady wake transport mechanism in the blade passage.

Sadat, Eddieb, Mostaan Lotfalian Saremi e Alparslan Emrah Bayrak. "A Two-Timescale Reinforcement Learning Approach for Control Co-Design Problems". In ASME 2023 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/detc2023-116567.

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Abstract Design of smart (or active) systems that perform automated tasks intelligently based on the interaction with their environments requires a collective solution of the physical and control system design problems together. In this paper, we present a model-free on-policy reinforcement learning approach to solve control co-design problems for such smart systems. This approach uses a discrete two timescale reinforcement learning that addresses the control system design in an inner loop with a fast time scale and the physical system design in an outer loop with a slower time scale. Both design problems use the same temporal difference-based Q-learning formulation. We apply this two-time-scale reinforcement approach to the online video game EcoRacer where the physical system involves the design of a gear ratio for an electric vehicle and the control system involves acceleration and braking decisions over time to finish a track with minimum energy consumption within a limited time. The results show the ability of the proposed approach to find the system optimal solution for the EcoRacer case study within a reasonable computation time without requiring any knowledge of the physics governing the system. The proposed method is generalizable and has the potential to take advantage of the ongoing developments in the field of reinforcement learning.

Lian, Huan, Jason Martz, Niket Prakash e Anna Stefanopoulou. "Fast Computation of Combustion Phasing and its Influence on Classifying Random or Deterministic Patterns". In ASME 2015 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/icef2015-1173.

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The classification between a sequence of highly variable combustion events that have an underlying deterministic pattern and a sequence of combustion events with similar level of variability but random characteristics is important for control of combustion phasing. In the case of high cyclic variation (CV) with underlying deterministic patterns, it is possible to apply closed loop combustion control on a cyclic-basis with a fixed mean value, such as injection timing in homogeneous charge compression ignition (HCCI) or spark timing in spark ignition (SI) applications, to contract the CV. In the case of a random distribution, the high CV can be avoided by shifting operating conditions away from the unstable region via advancing or retarding the injection timing or the spark timing in the mean-sense. Therefore, the focus of this paper is on the various methods of computing CA50 for analysing and classifying cycle-to-cycle variability. The assumptions made to establish fast and possibly on-line methods can alter the distribution of the calculated parameters from cycle-to-cycle, possibly leading to incorrect pattern interpretation and improper control action. Finally, we apply a statistical technique named “permutation entropy” for the first time on classifying combustion patterns in HCCI and SI engine for varying operating condition. Then the various fast methods for computing CA50 feed the two statistical methods, permutation and the Shannon entropy, and their differences and similarities are highlighted.

Nonomura, Taku, Hiroko Muranaka e Kozo Fujii. "Computational Analysis of Various Factors on the Edgetone Mechanism Using High Order Schemes". In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77220.

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Flow fields of two dimensional jets impinging on the sharp edge are computationally simulated and the effect of various parameters on the edgetone that is created by the flow interaction is investigated. Compressible Navier-Stokes equations are used so that acoustic waves are captured accurately as a part of feedback-loop. For numerical accuracy, Pade type compact finite difference scheme are used. First parameter is the jet velocity. Computational result shows good qualitative agreement with the experiment. Edgetone frequencies obtained by the computation also show good correspondence with those of experimental study in the past. Second parameter is the nozzle lip thickness. Although not considered in the computational study in the past, the nozzle lip thickness influences to the results. Amplitude of acoustics of larger nozzle lip is greater than that of smaller ones. This effect may comes from the fact that acoustic wave as a part of feedback loop is emphasized by nozzle lip. Third parameter is the jet-profile. Four different jet-profiles with the same maximum velocity (from top-hat profile to parabolic profile) and four different jet-profiles with the same mean velocity are computed. The mean jet velocity appears to have strong influence on the stage. The results also indicated that the mean jet velocity and the jet-profile have influence on edgetone frequencies.

Caponnetto, Mario. "Optimisation and Design of Contra-Rotating Propellers". In SNAME 9th Propeller and Shafting Symposium. SNAME, 2000. http://dx.doi.org/10.5957/pss-2000-03.

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A new method for the optimisation and design of Contra-Rotating Propellers (CRP) is presented in this paper. It is based on a Genetic Algorithm (GA) applied to a Vortex Lattice Method, used to compute the optimum spanwise distribution of circulation. chord length and thickness. Computation of the pitch and camber distribution is then performed with a design Panel Method (DPM). Both codes are used in a loop of iterations in order to take into account of the reciprocal interaction of the two propellers and their wakes. Blade optimisation is performed within several constraints such as cavitation avoidance and structural strength requirements.

Sammak, Majed, Marcus Thern e Magnus Genrup. "Reduced-Order Through-Flow Design Code for Highly Loaded, Cooled Axial Turbines". In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95469.

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The development of advanced computational fluid dynamic codes for turbine design does not substitute the importance of mean-line codes. Turbine design involves mean-line design, through-flow design, airfoil design, and finally 3D viscous modeling. The preliminary mean-line design continues to play an important role in early design stages. The aim of this paper was to present the methodology of mean-line designing of axial turbines and to discuss the computational methods and procedures used. The paper presents the Lund University Axial Turbine mean-line code (LUAX-T). LUAX-T is a reduced-order through-flow tool that is capable of designing highly loaded, cooled axial turbines. The stage computation consists of three iteration loops — cooling, entropy, and geometry iteration loop. The stage convergence method depends on whether the stage is part of the compressor turbine (CT) or power turbine (PT) stages, final CT stage, or final PT stage. LUAX-T was developed to design axial single- and twin-shaft turbines, and various working fluid and fuel compositions can be specified. LUAX-T uses the modified Ainley and Mathieson loss model, with the cooling computation based on the m*-model. Turbine geometries were established by applying various geometry correlations and methods. The validation was performed against a test turbine that was part of a European turbine development program. LUAX-T validated the axial PT of the test turbine, which consisted of two stages with rotational speed 13000 rpm. LUAX-T showed good agreement with the available performance data on the test turbine. The paper presented also the mean-line design of an axial cooled twin-shaft turbine. Design parameters were kept within limits of current practice. The total turbine power was 109 MW, of which the CT power was 55 MW. The CT was designed with two stages with a rotational speed of 9500 rpm, while the PT had two stages with a rotational speed of 6200 rpm. The total cooling mass flow was calculated to 31 kg/s, which corresponds to 23 % of compressor inlet mass flow. LUAX-T proved capable of designing uncooled and cooled turbines.

Rapporti di organizzazioni sul tema "Two-Loop computation":

Hawley, Owston e Thorson. PR-015-13610-R01 Effect of Upstream Piping Configuration on Ultrasonic Meter Bias - Flow Validation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), dicembre 2014. http://dx.doi.org/10.55274/r0010033.

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This research demonstrated the ability of a Computational Fluid Dynamics (CFD) modeling approach to predict the severity of velocity profile disturbances in two different header configurations with AGA-9 default meter runs. The CFD model was also used to predict the flow measurement error based on the ultrasonic path geometry from four commercially-available ultrasonic flow meters. In addition to the CFD modeling, this project experimentally tested the same two header configurations in a natural gas flow loop. The results from the experimental testing were used to validate the CFD model.

Idakwo, Gabriel, Sundar Thangapandian, Joseph Luttrell, Zhaoxian Zhou, Chaoyang Zhang e Ping Gong. Deep learning-based structure-activity relationship modeling for multi-category toxicity classification : a case study of 10K Tox21 chemicals with high-throughput cell-based androgen receptor bioassay data. Engineer Research and Development Center (U.S.), luglio 2021. http://dx.doi.org/10.21079/11681/41302.

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Deep learning (DL) has attracted the attention of computational toxicologists as it offers a potentially greater power for in silico predictive toxicology than existing shallow learning algorithms. However, contradicting reports have been documented. To further explore the advantages of DL over shallow learning, we conducted this case study using two cell-based androgen receptor (AR) activity datasets with 10K chemicals generated from the Tox21 program. A nested double-loop cross-validation approach was adopted along with a stratified sampling strategy for partitioning chemicals of multiple AR activity classes (i.e., agonist, antagonist, inactive, and inconclusive) at the same distribution rates amongst the training, validation and test subsets. Deep neural networks (DNN) and random forest (RF), representing deep and shallow learning algorithms, respectively, were chosen to carry out structure-activity relationship-based chemical toxicity prediction. Results suggest that DNN significantly outperformed RF (p < 0.001, ANOVA) by 22–27% for four metrics (precision, recall, F-measure, and AUPRC) and by 11% for another (AUROC). Further in-depth analyses of chemical scaffolding shed insights on structural alerts for AR agonists/antagonists and inactive/inconclusive compounds, which may aid in future drug discovery and improvement of toxicity prediction modeling.

Or, Etti, David Galbraith e Anne Fennell. Exploring mechanisms involved in grape bud dormancy: Large-scale analysis of expression reprogramming following controlled dormancy induction and dormancy release. United States Department of Agriculture, dicembre 2002. http://dx.doi.org/10.32747/2002.7587232.bard.

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The timing of dormancy induction and release is very important to the economic production of table grape. Advances in manipulation of dormancy induction and dormancy release are dependent on the establishment of a comprehensive understanding of biological mechanisms involved in bud dormancy. To gain insight into these mechanisms we initiated the research that had two main objectives: A. Analyzing the expression profiles of large subsets of genes, following controlled dormancy induction and dormancy release, and assessing the role of known metabolic pathways, known regulatory genes and novel sequences involved in these processes B. Comparing expression profiles following the perception of various artificial as well as natural signals known to induce dormancy release, and searching for gene showing similar expression patterns, as candidates for further study of pathways having potential to play a central role in dormancy release. We first created targeted EST collections from V. vinifera and V. riparia mature buds. Clones were randomly selected from cDNA libraries prepared following controlled dormancy release and controlled dormancy induction and from respective controls. The entire collection (7920 vinifera and 1194 riparia clones) was sequenced and subjected to bioinformatics analysis, including clustering, annotations and GO classifications. PCR products from the entire collection were used for printing of cDNA microarrays. Bud tissue in general, and the dormant bud in particular, are under-represented within the grape EST database. Accordingly, 59% of the our vinifera EST collection, composed of 5516 unigenes, are not included within the current Vitis TIGR collection and about 22% of these transcripts bear no resemblance to any known plant transcript, corroborating the current need for our targeted EST collection and the bud specific cDNA array. Analysis of the V. riparia sequences yielded 814 unigenes, of which 140 are unique (keilin et al., manuscript, Appendix B). Results from computational expression profiling of the vinifera collection suggest that oxidative stress, calcium signaling, intracellular vesicle trafficking and anaerobic mode of carbohydrate metabolism play a role in the regulation and execution of grape-bud dormancy release. A comprehensive analysis confirmed the induction of transcription from several calcium–signaling related genes following HC treatment, and detected an inhibiting effect of calcium channel blocker and calcium chelator on HC-induced and chilling-induced bud break. It also detected the existence of HC-induced and calcium dependent protein phosphorylation activity. These data suggest, for the first time, that calcium signaling is involved in the mechanism of dormancy release (Pang et al., in preparation). We compared the effects of heat shock (HS) to those detected in buds following HC application and found that HS lead to earlier and higher bud break. We also demonstrated similar temporary reduction in catalase expression and temporary induction of ascorbate peroxidase, glutathione reductase, thioredoxin and glutathione S transferase expression following both treatments. These findings further support the assumption that temporary oxidative stress is part of the mechanism leading to bud break. The temporary induction of sucrose syntase, pyruvate decarboxylase and alcohol dehydrogenase indicate that temporary respiratory stress is developed and suggest that mitochondrial function may be of central importance for that mechanism. These finding, suggesting triggering of identical mechanisms by HS and HC, justified the comparison of expression profiles of HC and HS treated buds, as a tool for the identification of pathways with a central role in dormancy release (Halaly et al., in preparation). RNA samples from buds treated with HS, HC and water were hybridized with the cDNA arrays in an interconnected loop design. Differentially expressed genes from the were selected using R-language package from Bioconductor project called LIMMA and clones showing a significant change following both HS and HC treatments, compared to control, were selected for further analysis. A total of 1541 clones show significant induction, of which 37% have no hit or unknown function and the rest represent 661 genes with identified function. Similarly, out of 1452 clones showing significant reduction, only 53% of the clones have identified function and they represent 573 genes. The 661 induced genes are involved in 445 different molecular functions. About 90% of those functions were classified to 20 categories based on careful survey of the literature. Among other things, it appears that carbohydrate metabolism and mitochondrial function may be of central importance in the mechanism of dormancy release and studies in this direction are ongoing. Analysis of the reduced function is ongoing (Appendix A). A second set of hybridizations was carried out with RNA samples from buds exposed to short photoperiod, leading to induction of bud dormancy, and long photoperiod treatment, as control. Analysis indicated that 42 genes were significant difference between LD and SD and 11 of these were unique.

Development of an Adaptive Efficient Thermal/Electric Skipping Control Strategy Applied to a Parallel Plug-in Hybrid Electric Vehicle. SAE International, marzo 2022. http://dx.doi.org/10.4271/2022-01-0737.

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In recent years automobile manufacturers focused on an increasing degree of electrification of the powertrains with the aim to reduce pollutants and CO2 emissions. Despite more complex design processes and control strategies, these powertrains offer improved fuel exploitation compared to conventional vehicles thanks to intelligent energy management. A simulation study is here presented aiming at developing a new control strategy for a P3 parallel plug-in hybrid electric vehicle. The simulation model is implemented using vehicle modeling and simulation toolboxes in MATLAB/Simulink. The proposed control strategy is based on an alternative utilization of the electric motor and thermal engine to satisfy the vehicle power demand at the wheels (Efficient Thermal/Electric Skipping Strategy - ETESS). The choice between the two units is realized through a comparison between two equivalent fuel rates, one related to the thermal engine and the other related to the electric consumption. An adaptive function is introduced to develop a charge-blended control strategy. The novel adaptive control strategy (A-ETESS) is applied to estimate fuel consumption along different driving cycles. The control algorithm is implemented on a dedicated microcontroller unit performing a Processor-In-the-Loop (PIL) simulation. To demonstrate the reliability and effectiveness of the A-ETESS, the same adaptive function is built on the Equivalent Consumption Minimization Strategy (ECMS). The PIL results showed that the proposed strategy ensures a fuel economy similar to ECMS (worse of about 2% on average) and a computational effort reduced by 99% on average. This last feature reveals the potential for real-time on-vehicle applications.