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Articoli di riviste sul tema "Two-Loop computation"

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Autore: Grafiati
Pubblicato: 22 giugno 2024

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1

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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2

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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3

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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Abstract (sommario):
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.
4

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.
5

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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6

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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7

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×.
8

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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9

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.
10

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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11

Bode, Achim, Peter Weisz e Ulli Wolff. "Erratum to “Two loop computation of the Schrödinger functional in lattice QCD”". Nuclear Physics B 600, n. 2 (aprile 2001): 453. http://dx.doi.org/10.1016/s0550-3213(01)00045-1.

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12

Bode, Achim, Peter Weisz e Ulli Wolff. "Erratum to: “Two loop computation of the Schrödinger functional in lattice QCD”". Nuclear Physics B 608, n. 1-2 (agosto 2001): 481. http://dx.doi.org/10.1016/s0550-3213(01)00267-x.

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13

Caracciolo, Sergio, Andrea Pelissetto e Antonio Rago. "High-accuracy two-loop computation of the critical mass for Wilson fermions". Nuclear Physics B - Proceedings Supplements 106-107 (marzo 2002): 835–37. http://dx.doi.org/10.1016/s0920-5632(01)01859-x.

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14

Iengo, Roberto, e Chuan-Jie Zhu. "Two-loop computation of the four-particle amplitude in heterotic string theory". Physics Letters B 212, n. 3 (settembre 1988): 313–19. http://dx.doi.org/10.1016/0370-2693(88)91322-6.

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15

Narayanan, Rajamani, e Ulli Wolff. "Two-loop computation of a running coupling in lattice Yang-Mills theory". Nuclear Physics B 444, n. 1-2 (giugno 1995): 425–46. http://dx.doi.org/10.1016/0550-3213(95)00170-w.

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16

Wolff, Ulli. "Two-loop computation of a finite volume running coupling on the lattice". Nuclear Physics B - Proceedings Supplements 42, n. 1-3 (aprile 1995): 291–93. http://dx.doi.org/10.1016/0920-5632(95)00230-7.

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17

Kolganov, Alexander Sergeevich, e Nikita Andreevich Kataev. "Data distribution and parallel code generation for heterogeneous computational clusters". Proceedings of the Institute for System Programming of the RAS 34, n. 4 (2022): 89–100. http://dx.doi.org/10.15514/ispras-2022-34(4)-7.

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Abstract (sommario):
We present new techniques for compilation of sequential programs for almost affine accesses in loop nests for distributed-memory parallel architectures. Our approach is implemented as a source-to-source automatic parallelizing compiler that expresses parallelism with the DVMH directive-based programming model. Compared to all previous approaches ours addresses all three main sub-problems of the problem of distributed memory parallelization: data and computation distribution and communication optimization. Parallelization of sequential programs with structured grid computations is considered. In this paper, we use the NAS Parallel Benchmarks to evaluate the performance of generated programs and provide experimental results on up to 9 nodes of a computational cluster with two 8-core processors in a node.
18

Juang, Jer-Nan, James D. Turner e Hon M. Chun. "Closed-Form Solutions for a Class of Optimal Quadratic Regulator Problems With Terminal Constraints". Journal of Dynamic Systems, Measurement, and Control 108, n. 1 (1 marzo 1986): 44–48. http://dx.doi.org/10.1115/1.3143741.

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Closed-form solutions are derived for coupled Riccati-like matrix differential equations describing the solution of a class of optimal finite time quadratic regulator problems with terminal constraints. Analytical solutions are obtained for the feedback gains and the closed-loop response trajectory. A computational procedure is presented which introduces new variables for efficient computation of the terminal control law. Two examples are given to illustrate the validity and usefulness of the theory.
19

Zhuo, Youwei, Jingji Chen, Gengyu Rao, Qinyi Luo, Yanzhi Wang, Hailong Yang, Depei Qian e Xuehai Qian. "Distributed Graph Processing System and Processing-in-memory Architecture with Precise Loop-carried Dependency Guarantee". ACM Transactions on Computer Systems 37, n. 1-4 (giugno 2021): 1–37. http://dx.doi.org/10.1145/3453681.

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To hide the complexity of the underlying system, graph processing frameworks ask programmers to specify graph computations in user-defined functions (UDFs) of graph-oriented programming model. Due to the nature of distributed execution, current frameworks cannot precisely enforce the semantics of UDFs, leading to unnecessary computation and communication. It exemplifies a gap between programming model and runtime execution. This article proposes novel graph processing frameworks for distributed system and Processing-in-memory (PIM) architecture that precisely enforces loop-carried dependency; i.e., when a condition is satisfied by a neighbor, all following neighbors can be skipped. Our approach instruments the UDFs to express the loop-carried dependency, then the distributed execution framework enforces the precise semantics by performing dependency propagation dynamically. Enforcing loop-carried dependency requires the sequential processing of the neighbors of each vertex distributed in different nodes. We propose to circulant scheduling in the framework to allow different nodes to process disjoint sets of edges/vertices in parallel while satisfying the sequential requirement. The technique achieves an excellent trade-off between precise semantics and parallelism—the benefits of eliminating unnecessary computation and communication offset the reduced parallelism. We implement a new distributed graph processing framework SympleGraph, and two variants of runtime systems— GraphS and GraphSR —for PIM-based graph processing architecture, which significantly outperform the state-of-the-art.
20

Bode, Achim, Ulli Wolff e Peter Weisz. "Two-loop computation of the Schrödinger functional in pure SU(3) lattice gauge theory". Nuclear Physics B 540, n. 1-2 (febbraio 1999): 491–99. http://dx.doi.org/10.1016/s0550-3213(98)00772-x.

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21

Haynes, Brandon, Rana Alotaibi, Anna Pavlenko, Jyoti Leeka, Alekh Jindal e Yuanyuan Tian. "GEqO: ML-Accelerated Semantic Equivalence Detection". Proceedings of the ACM on Management of Data 1, n. 4 (8 dicembre 2023): 1–25. http://dx.doi.org/10.1145/3626710.

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Abstract (sommario):
Large scale analytics engines have become a core dependency for modern data-driven enterprises to derive business insights and drive actions. These engines support a large number of analytic jobs processing huge volumes of data on a daily basis, and workloads are often inundated with overlapping computations across multiple jobs. Reusing common computation is crucial for efficient cluster resource utilization and reducing job execution time. Detecting common computation is the first and key step for reducing this computational redundancy. However, detecting equivalence on large-scale analytics engines requires efficient and scalable solutions that are fully automated. In addition, to maximize computation reuse, equivalence needs to be detected at the semantic level instead of just the syntactic level (i.e., the ability to detect semantic equivalence of seemingly different-looking queries). Unfortunately, existing solutions fall short of satisfying these requirements. In this paper, we take a major step towards filling this gap by proposing GEqO, a portable and lightweight machine-learning-based framework for efficiently identifying semantically equivalent computations at scale. GEqO introduces two machine-learning-based filters that quickly prune out nonequivalent subexpressions and employs a semi-supervised learning feedback loop to iteratively improve its model with an intelligent sampling mechanism. Further, with its novel database-agnostic featurization method, GEqO can transfer the learning from one workload and database to another. Our extensive empirical evaluation shows that, on TPC-DS-like queries, GEqO yields significant performance gains-up to 200x faster than automated verifiers-and finds up to 2x more equivalences than optimizer and signature-based equivalence detection approaches.
22

MORRIS, TIM R., e JOHN F. TIGHE. "CONVERGENCE OF DERIVATIVE EXPANSIONS IN SCALAR FIELD THEORY". International Journal of Modern Physics A 16, n. 11 (30 aprile 2001): 2095–100. http://dx.doi.org/10.1142/s0217751x01004761.

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The convergence of the derivative expansion of the exact renormalisation group is investigated via the computation of the β function of massless scalar λφ4 theory. The derivative expansion of the Polchinski flow equation converges at one loop for certain fast falling smooth cutoffs. Convergence of the derivative expansion of the Legendre flow equation is trivial at one loop, but also can occur at two loops and in particular converges for an exponential cutoff.
23

Opeiko, O. F. "CONTROL SYNTHESIS FOR TWO LOOPS DISCRET SYSTEM". «System analysis and applied information science», n. 1 (12 giugno 2018): 22–26. http://dx.doi.org/10.21122/2309-4923-2018-1-22-26.

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The aim of this paper is the linear synthesis of two loops SISO systems with discreet time proportional integral (PI) controllers. This linear synthesis is dedicated for the systems with plant parameters uncertainty. The synthesis is based on the time scale method, providing the separate slow and fast components of the control low. The PI- controller parameters calculation is based on the modal control and plant model reduction. The conditions carried out for the each control loop dynamics still similar to the second order one. The discrete time microcontroller based numerical control restricts the stability domain of the system and each control loop in it. The stability domain of each loop is the round on the complex plane with radius, depending on the time period. Each inner loop must be more fast, then each outer one. Hence, in the outer loop the time period, required for the PI controller reaction computation, can be more then in the inner loop. This PI- controller parameter calculation method is approximate, and it is efficient for the systems, whose dynamics contains the slow and fast components. In particular, the electrical drives control systems contain the fast electromagnetic component and the slow mechanical part. The effectiveness of this method is illustrated by the example and simulation.
24

GOMES, M., J. M. C. MALBOUISSON e A. J. DA SILVA. "ON THE NONRELATIVISTIC LIMIT OF THE φ4 THEORY IN 2+1 DIMENSIONS". Modern Physics Letters A 11, n. 36 (30 novembre 1996): 2825–36. http://dx.doi.org/10.1142/s0217732396002812.

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We study the nonrelativistic limit of the quantum theory of a real scalar field with quartic self-interaction. The two-body scattering amplitude is written in such way as to separate the contributions of high and low energy intermediary states. From this result and the two-loop computation of the self-energy correction, we determine an effective nonrelativistic action.
25

Preti, Michelangelo. "STR: A Mathematica package for the method of uniqueness". International Journal of Modern Physics C 31, n. 10 (16 settembre 2020): 2050146. http://dx.doi.org/10.1142/s0129183120501466.

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We present Star–Triangle Relations (STRs), a Mathematica® package designed to solve Feynman diagrams by means of the method of uniqueness in any Euclidean space-time dimension. The method of uniqueness is a powerful technique to solve multi-loop Feynman integrals in theories with conformal symmetry imposing some relations between the powers of propagators and the space-time dimension. In our algorithm, we include both identities for scalar and Yukawa type integrals. The package provides a graphical environment in which it is possible to draw the desired diagram with the mouse input and a set of tools to modify and compute it. Throughout the use of a graphic interface, the package should be easily accessible to users with little or no previous experience on diagrams computation. This manual includes some pedagogical examples of computation of Feynman graphs as the scalar two-loop kite master integral and a fermionic diagram appearing in the computation of the spectrum of the [Formula: see text]-deformed [Formula: see text] SYM in the double scaling limit.
26

Bakshi, S., D. Deshmukh e R. V. Ravikrishna. "Multidimensional modelling of flow through piston-controlled ports using a multi-block, moving mesh algorithm". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 218, n. 2 (1 febbraio 2004): 207–22. http://dx.doi.org/10.1243/095440604322887062.

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In the present work, a complete algorithm is presented to simulate the gas exchange process across domains in a multi-block computation involving a piston-controlled port. The moving boundary scheme of Peric is used in conjunction with the zonal boundary scheme of Rai. The algorithm has been applied to two cases. The first case involves a typical air-filling process through the piston-operated port of a pneumatic pump, and the analysis shows that flowfield variable information is smoothly communicated across the zonal boundary using this algorithm. The second case involves modelling of the scavenging process in a loop-scavenged two-stroke internal combustion (IC) engine. In this case, the stepwise evolution of the scavenging flow in the engine cylinder is studied. Initiation of short circuiting at early stages of scavenging, tilting of the inlet flow in directions different from inlet port angles and the existence of a low-purity swirling loop in the exhaust-side top corner of the engine cylinder are observed from the flowfield computations.
27

Li, Zun, e Michael P. Wellman. "Evolution Strategies for Approximate Solution of Bayesian Games". Proceedings of the AAAI Conference on Artificial Intelligence 35, n. 6 (18 maggio 2021): 5531–40. http://dx.doi.org/10.1609/aaai.v35i6.16696.

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We address the problem of solving complex Bayesian games, characterized by high-dimensional type and action spaces, many (> 2) players, and general-sum payoffs. Our approach applies to symmetric one-shot Bayesian games, with no given analytic structure. We represent agent strategies in parametric form as neural networks, and apply natural evolution strategies (NES) [wierstra2014natural] for deep model optimization. For pure equilibrium computation, we formulate the problem as bi-level optimization, and employ NES in an iterative algorithm to implement both inner-loop best response optimization and outer-loop regret minimization. In simple games including first- and second-price auctions, it is capable of recovering known analytic solutions. For mixed equilibrium computation, we adopt an incremental strategy generation framework, with NES as strategy generator producing a finite sequence of approximate best-response strategies. We then calculate equilibria over this finite strategy set via a model-based optimization process. Both our pure and mixed equilibrium computation methods employ NES to efficiently search for strategies over the functional space, given only black-box simulation access to noisy payoff samples. We experimentally demonstrate the efficacy of all methods on two simultaneous sealed-bid auction games with distinct type distributions, and observe that the solutions exhibit qualitatively different behavior in these two environments.
28

Kloock, Maximilian, Patrick Scheffe e Bassam Alrifaee. "Testing distributed trajectory planning in the cyber-physical mobility lab". at - Automatisierungstechnik 71, n. 4 (1 aprile 2023): 317–25. http://dx.doi.org/10.1515/auto-2022-0154.

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Abstract This article presents the testing of distributed trajectory planning algorithms using our rapid prototyping platform, the Cyber-Physical Mobility Lab (CPM Lab). We propose two algorithms for distributed trajectory planning which plan trajectories at intersections, highway on- and off-ramps, and lane changes for networked and autonomous vehicles. The algorithms avoid collisions between vehicles using a synchronization-based and a prioritized Distributed Model Predictive Control (DMPC) strategy. We test two algorithms in the CPM Lab which is able to handle parallel, sequential, and hybrid computations. The CPM Lab achieves reproducible experiments under non-deterministic computation times and stochastic communication times. Our evaluation shows that different algorithms for distributed trajectory planning can be efficiently tested in different in-the-loop tests.
29

Zhu, Zhongyang, Guangmin Sun, Anqi Liu e Cunfu He. "An Evolutionary Computation-Based Method for Nondestructive Tensile Force Measurements in Two Materials Using Hysteresis Loop". IEEE Transactions on Instrumentation and Measurement 69, n. 9 (settembre 2020): 6281–95. http://dx.doi.org/10.1109/tim.2020.2969093.

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30

Wu, Xing, Jorge Angeles, Ting Zou, Haining Xiao, Wei Li e Peihuang Lou. "Steering-angle computation for the multibody modelling of differential-driving mobile robots with a caster". International Journal of Advanced Robotic Systems 15, n. 6 (1 novembre 2018): 172988141882016. http://dx.doi.org/10.1177/1729881418820166.

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Abstract (sommario):
Since many off-the-shelf motor drives are supplied with complete control capability in the current, velocity and position loop, the robot model in the navigation control architecture can be oriented either to kinematics, interfaced with the velocity loop, or to dynamics, with the motor-current loop. Moreover, no constraints are imposed by a caster on the mobility of differential-driving mobile robots. Hence, a reduced model, containing only the platform, is sufficient for navigation control based only on the robot kinematics. However, if the multibody system model is used for navigation control based on the robot dynamics, to cope with the demands of high-speed manoeuvres and/or heavy-load operations, then the caster kinematics, especially the knowledge of the steering angle, is required to calculate the inertia matrix and the terms of Coriolis and centrifugal forces. While this angle can be measured by means of dedicated encoders to be installed for casters, the computation technique based on the existing tachometers, already mounted on the motor shafts for the servo control of the two driving wheels, is proved to be sufficient. Both a thorough kinematics model and a multibody dynamics model, including the platform and all different wheels, are formulated here for differential-driving mobile robots. Computational methods based on velocity compatibility and rigid body twists are proposed to estimate the steering angle. Simulation results of the differential-driving mobile robot moving on a smooth trajectory show the feasibility of the steering-angle computational scheme, which obviates the need of installing caster encoders. Moreover, a performance comparison on system modelling is implemented via simulation, between the differential-driving mobile robot model with and without caster dynamics. This further validates the importance of the dynamic effects of casters on the whole system model. Therefore, the multibody modelling approach for casters with the steering-angle computation technique can facilitate the navigation control architecture under dynamics conditions.
31

Szustak, Lukasz, Krzysztof Rojek, Tomasz Olas, Lukasz Kuczynski, Kamil Halbiniak e Pawel Gepner. "Adaptation of MPDATA Heterogeneous Stencil Computation to Intel Xeon Phi Coprocessor". Scientific Programming 2015 (2015): 1–14. http://dx.doi.org/10.1155/2015/642705.

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The multidimensional positive definite advection transport algorithm (MPDATA) belongs to the group of nonoscillatory forward-in-time algorithms and performs a sequence of stencil computations. MPDATA is one of the major parts of the dynamic core of the EULAG geophysical model. In this work, we outline an approach to adaptation of the 3D MPDATA algorithm to the Intel MIC architecture. In order to utilize available computing resources, we propose the (3 + 1)D decomposition of MPDATA heterogeneous stencil computations. This approach is based on combination of the loop tiling and fusion techniques. It allows us to ease memory/communication bounds and better exploit the theoretical floating point efficiency of target computing platforms. An important method of improving the efficiency of the (3 + 1)D decomposition is partitioning of available cores/threads into work teams. It permits for reducing inter-cache communication overheads. This method also increases opportunities for the efficient distribution of MPDATA computation onto available resources of the Intel MIC architecture, as well as Intel CPUs. We discuss preliminary performance results obtained on two hybrid platforms, containing two CPUs and Intel Xeon Phi. The top-of-the-line Intel Xeon Phi 7120P gives the best performance results, and executes MPDATA almost 2 times faster than two Intel Xeon E5-2697v2 CPUs.
32

Tan, Lintao, Nikolaos Christos Tsamis e Richard Paul Woodard. "How Inflationary Gravitons Affect the Force of Gravity". Universe 8, n. 7 (8 luglio 2022): 376. http://dx.doi.org/10.3390/universe8070376.

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We employ an unregulated computation of the graviton self-energy from gravitons on the de Sitter background to infer the renormalized result. This is used to quantum-correct the linearized Einstein equation. We solve this equation for the potentials that represent the gravitational response to a static, point mass. We find large spatial and temporal logarithmic corrections to the Newtonian potential and to the gravitational shift. Although suppressed by a minuscule loop-counting parameter, these corrections cause perturbation theory to break down at large distances and late times. Another interesting fact is that gravitons induce up to three large logarithms, whereas a loop of massless, minimally coupled scalars produces only a single large logarithm. This is in line with corrections to the graviton mode function: a loop of gravitons induces two large logarithms, whereas a scalar loop gives none.
33

Cao, Zhen Nan, e Bo Shen. "Research on Parallel Computation Architecture Based on Object Computing Network". Advanced Materials Research 317-319 (agosto 2011): 374–85. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.374.

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In this paper, a multi-body system dynamics problem is considered as a complex system modeling and computation problem. A parallel programming model and its execution environment are designed to reduce model complexity and to improve computational speed. In this architecture, the problem is divided into two levels: 1. Find a parallel mathematical algorithm to describe the behavior of this multi-body system. 2. Build a unified programming language that could leverage many different pieces of computational resources, such as symbolic computing, and numerical libraries. To tackle the first level, Space-Time Finite Element Method (FEM) is applied. The Space-Time FEM formats of Newton-Euler formula is given, as well as its constraint formula. This algorithm has avoided the loop operation during the time field solving. To tackle the second level, a network-based functional programming language - Object Computing Network (OCN) is designed. OCN is inspired by Object-Process Methodology (OPM). In OCN, every computation behavior is treated as a function, which is constructed by a three element set: {Var, Rule. Condition}. Three basic patterns - Branching, Synchronizing, Merging are given in OCN to prove the flexibility of OCN. An communication interface is designed in OCN to connect different programming languages together. Two multi-body system dynamics computing models - Semi-discretization method and Space-Time discretization method - are constructed with OCN, and a significant contrast in task parallelization is shown by different OCN models.
34

Caluwaerts, K., M. D'Haene, D. Verstraeten e B. Schrauwen. "Locomotion Without a Brain: Physical Reservoir Computing in Tensegrity Structures". Artificial Life 19, n. 1 (gennaio 2013): 35–66. http://dx.doi.org/10.1162/artl_a_00080.

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Embodiment has led to a revolution in robotics by not thinking of the robot body and its controller as two separate units, but taking into account the interaction of the body with its environment. By investigating the effect of the body on the overall control computation, it has been suggested that the body is effectively performing computations, leading to the term morphological computation. Recent work has linked this to the field of reservoir computing, allowing one to endow morphologies with a theory of universal computation. In this work, we study a family of highly dynamic body structures, called tensegrity structures, controlled by one of the simplest kinds of “brains.” These structures can be used to model biomechanical systems at different scales. By analyzing this extreme instantiation of compliant structures, we demonstrate the existence of a spectrum of choices of how to implement control in the body-brain composite. We show that tensegrity structures can maintain complex gaits with linear feedback control and that external feedback can intrinsically be integrated in the control loop. The various linear learning rules we consider differ in biological plausibility, and no specific assumptions are made on how to implement the feedback in a physical system.
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Jaw, Shenq-Yuh, e Alpha Y. Wang. "Parallel Computation of Turbulent Flows Using Equation Decomposition Scheme". Journal of Mechanics 14, n. 3 (settembre 1998): 137–44. http://dx.doi.org/10.1017/s1727719100000162.

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ABSTRACTA problem independent, equation decomposition scheme of parallel computation is adopted and tested using a two-dimensional turbulent channel flow. The incompressible Navier-Stokes equations, incorporated with the SIMPLEC algorithm and a two-layer turbulence model, were distributed to four nodes of IBM SP2 parallel machine using the PVM software and solved simultaneously. The computation domain and the interior iteration loop for the solution of every transport equation is the same, load balancing among different machines is automatically satisfied. Since all the transport equations and the flow field was solved and updated simultaneously, the solutions obtained from the equation decomposition scheme at each time step were more accurate than those obtained from a unit process code, which in turn sharply reduced the required convergence time steps. Without modifying any of the solution algorithm, or tuning the computer code, the rate of convergence speeds up more than four times by invoking four nodes of parallel machines using the equation decomposition scheme.
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Abe, Akira, e Keisuke Okabe. "Antisway Control for a Rotary Crane by Using Evolutionary Computation". Journal of Robotics and Mechatronics 28, n. 5 (20 ottobre 2016): 646–53. http://dx.doi.org/10.20965/jrm.2016.p0646.

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[abstFig src='/00280005/05.jpg' width='250' text='Photograph of the experimental setup' ] We present a simple antisway control method for a rotary crane, whose load can move in a two-dimensional plane. In particular, we investigate the suppression of residual sway motion of a rotary crane with a boom that performs point-to-point motion. In the proposed method, we attempt to generate the trajectory of the boom using a combination of polynomial and cycloidal functions. The profile of the generated trajectory depends on the coefficients of the polynomial function. Thus, it is necessary to tune the coefficients to minimize the sway motion in the two-dimensional plane as much as possible. We adopt a particle swarm optimization algorithm, an evolutionary computation technique, to tune the coefficients and then obtain the optimal trajectory. By rotating the boom along the optimal trajectory, the two-dimensional residual sway motion is suppressed, i.e., an open-loop control is realized. The effectiveness and feasibility of the proposed control scheme is demonstrated via simulations and experiments.
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Efimov, Olexander, Valerii Kavertsev e Petro Lifshyts. "Methods of the Strength Computation for the Covers, Bottoms, Assemblies and Elements of the Structure of Steam Generators Used by the Two-Loop Nuclear Power Plants with BBEP-1000 Reactors". NTU "KhPI" Bulletin: Power and heat engineering processes and equipment, n. 3-4 (28 dicembre 2022): 29–34. http://dx.doi.org/10.20998/2078-774x.2022.03.05.

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This scientific paper gives a review of the available methods and approaches used for the strength computation of the covers, bottoms, assemblies and elements of the structures of steam generators of the two-loop NPPs with BBEP-1000 reactors. For most assemblies and elements of the structures of steam generators of NPPs, the main strains arising in them are the consequences of the uniform internal and external pressures. However, in many cases the assemblies and elements of the structures of steam generators of NPPs can also be exposed to additional loads (weight loads, efforts and moments that result from nonhomogeneous thermal expansion of different parts of steam generator, etc.). The values of the strains caused by additional loads can sometimes exceed the value of the main strain. These can be decreased by the arrangement of additional supports or compensators or by changing the structure configuration. Sometimes, it is reasonable to increase the wall thickness of the calculated elements of the structures in order to reduce the strains caused by additional loads. Before getting to the strength computations for the assemblies and elements of the structures of steam generators we need to define first the character of the external loads on them (constant or cyclic load) and the deformability of their structural materials (ductile material, brittle material or limited plasticity material) and then to select the method for their strength computation. To provide a reliable operation of the steam generators of NPPs it is important to provide appropriate strength characteristics for all its assemblies and elements. These elements include process pipelines that are connected to the steam generator structure. These represent a spatially branched pipeline systems of a different technological purpose whose structures are supported by special fastening elements (the supports of different types, spring suspenders, etc.). The strength computations done for such systems include static and cyclic strength computations, seismic action computations, etc.
38

Zheng, X., C. Liao, C. Liu, C. H. Sung e T. T. Huang. "Multigrid Computation of Incompressible Flows Using Two-Equation Turbulence Models: Part II—Applications". Journal of Fluids Engineering 119, n. 4 (1 dicembre 1997): 900–905. http://dx.doi.org/10.1115/1.2819514.

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In this paper, computational results are presented for three-dimensional high-Reynolds number turbulent flows over a simplified submarine model. The simulation is based on the solution of Reynolds-Averaged Navier-Stokes equations and two-equation turbulence models by using a preconditioned time-stepping approach. A multiblock method, in which the block loop is placed in the inner cycle of a multi-grid algorithm, is used to obtain versatility and efficiency. It was found that the calculated body drag, lift, side force coefficients and moments at various angles of attack or angles of drift are in excellent agreement with experimental data. Fast convergence has been achieved for all the cases with large angles of attack and with modest drift angles.
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MANUEL, CRISTINA. "DIFFERENTIAL RENORMALIZATION OF A YUKAWA MODEL WITH γ5". International Journal of Modern Physics A 08, n. 18 (20 luglio 1993): 3223–34. http://dx.doi.org/10.1142/s0217751x93001296.

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We present a two-loop computation of the beta functions and the anomalous dimensions of a γ5 Yukawa model using differential renormalization. The calculation is carried out in coordinate space without modifying the space–time dimension and no ad hoc prescription for γ5 is needed. It is shown that this procedure is specially suited for theories involving γ5, and it should be considered in analyzing chiral gauge theories.
40

Bondarev, A. P., e A. M. Prystai. "The analytical model of measurement with GPS syncronization taking into account the stochastic effects". Information extraction and processing 2017, n. 45 (26 dicembre 2017): 38–49. http://dx.doi.org/10.15407/vidbir2017.45.038.

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A new structure for the diagram of measurements synchronization using GPS modules for two or more spaced stations is proposed. To simplify the modeling, a set of sources of GPS clock signals is replaced with a virtual reference generator with certain phase instability. The stochastic model is developed for synchronization of multiple devices. The cumulant and stochastic differential equations for the synchronization model are solved. The performed computation experiments made it possible to identify the model parameters, including loop gain, and factors of conversion and inertia of the loop. Implementation of the results into the structure of broadband magnetotelluric station LEMI-423 significantly reduced a measurement error produced by clock signal instability.
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Hirayama, T., B. Holdom, R. Koniuk e T. Yavin. "Classical simulation of quantum fields II". Canadian Journal of Physics 84, n. 10 (1 ottobre 2006): 879–90. http://dx.doi.org/10.1139/p06-082.

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We consider the classical time evolution of a real scalar field in two-dimensional Minkowski space with a [Formula: see text] interaction. We compute the spatial and temporal two-point correlation functions and extract the renormalized mass of the interacting theory. We find our results are consistent with the one- and two-loop quantum computation. We also perform Monte Carlo simulations of the quantum theory and conclude that the classical scheme is able to produce more accurate results with a fraction of the CPU time. PACS Nos.: 03.70.+k, 03.50.–z, 11.15.Tk
42

DONGEN, VINCENT VAN. "COMPILING DISTRIBUTED LOOPS ONTO SPMD CODE". Parallel Processing Letters 04, n. 03 (settembre 1994): 301–12. http://dx.doi.org/10.1142/s0129626494000284.

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Given a loop written in a sequential language and a block-cyclic distribution, we present some techniques for generating SPMD code to run on distributed-memory machines. This is illustrated on three types of loops: parallel loops without internal dependence, parallel loops with internal dependences, and loops with hidden parallelism. Two models of distributions are considered: the data distribution and the computation distribution. We argue here that the data distribution model together with the owner-computes rule is only well adapted for the first class of loops. For the other loops, we present the idea of using a computation distribution instead, and we show how this can be compiled for distributed-memory machines.
43

Chung, Mai Van, Do Tuan Anh, Phuong Vu e Linh Manh Nguyen. "Hardware in the loop co-simulation of finite set-model predictive control using FPGA for a three level CHB inverter". International Journal of Power Electronics and Drive Systems (IJPEDS) 11, n. 4 (1 dicembre 2020): 1719. http://dx.doi.org/10.11591/ijpeds.v11.i4.pp1719-1730.

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Along with the development of powerful microprocessors and microcontrollers, the applications of the model predictive controller, which requires high computational cost, to fast dynamical systems such as power converters and electric drives have become a tendency recently. In this paper, two solutions are offered to quickly develop the finite set predictive current control for induction motor fed by 3-level H-Bridge cascaded inverter. First, the field programmable gate array (FPGA) with capability of parallel computation is employed to minimize the computational time. Second, the hardware in the loop (HIL) co-simulation is used to quickly verify the developed control algorithm without burden of time on hardware design since the motor and the power switches are emulated on a real-time platform with high-fidelity mathematical models. The implementation procedure and HIL co-simulation results of the developed control algorithm shows the effectiveness of the proposed solution.
44

Chan, Jenq-Tzong H. "Optimal Output Feedback Regulator—A Numerical Synthesis Approach for Input-Output Data". Journal of Dynamic Systems, Measurement, and Control 118, n. 2 (1 giugno 1996): 360–66. http://dx.doi.org/10.1115/1.2802330.

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A numerical approach is proposed in this work for computing a linear quadratic optimal regulator from input-output data. The method is applicable whenever the plant is open-loop stable. The major advantages of the method are two-fold. First, it involves an output feedback control law; hence, no state estimation is required for implementation. Second, the computation of this optimal controller can be conducted without explicit identification of the plant model.
45

Berzoy, Alberto, Julio Viola e José Restrepo. "Voltage space vector‘s computation for current control in three phase converters". Revista Facultad de Ingeniería Universidad de Antioquia, n. 64 (3 ottobre 2012): 45–56. http://dx.doi.org/10.17533/udea.redin.13113.

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This work presents two current loop techniques, for three phase voltage source converters (VSC) used as controlled rectifiers (CR) operating at unity power factor. The first one is based on choosing the best natural vector, among the natural space vectors produced by two level voltage source inverters, with the use of a cost function. The second one is based on computing and synthesizing a space vector such that an absolute minimum in the cost function is obtained. The first algorithm is a simple method that presents power factor correction and good total harmonic distortion compensation. The second algorithm provides a novel and closed form formula to calculate the optimum voltage vector applied by the converter. In this method, pulse width modulation (PWM) is required to modulate the voltage vector that controls directly the line current, to follow the current reference. The simulations and experimental results show the advantages of the proposed control algorithm.
46

Yang, Xu, e Tian Ran Lin. "An active noise control algorithm based on an improved convex combination loop". Journal of the Acoustical Society of America 154, n. 4_supplement (1 ottobre 2023): A121. http://dx.doi.org/10.1121/10.0022986.

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The conflict between a faster convergence using a Filtered-X Least Mean Square (FXLMS) algorithm and the requirement of a small steady-state error of an adaptive active control (ANC) system which limits its performance in terms of computation efficiency and the control error. The problem can be solved by using two paralleling adaptive filters to form a convex combination loop in the control system. However, the exponential weight function used in the original convex combination loop design can consume a large computer power which has limited its application. As a result, a new weight function is proposed to replace the original exponential function in the original convex combination loop to enhance the convergence rate of the adaptive ANC system. Furthermore, a MRFXLMS algorithm is used to replace the FXLMS algorithm in the ANC system so that it can be used for impulse noise control. The result shows that the proposed algorithm performs well in the control of input impulse noise with different intensity.
47

Vreman, Nils, e Martina Maggio. "Stochastic Analysis of Control Systems Subject to Communication and Computation Faults". ACM Transactions on Embedded Computing Systems 22, n. 5s (9 settembre 2023): 1–25. http://dx.doi.org/10.1145/3609123.

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Control theory allows one to design controllers that are robust to external disturbances, model simplification, and modelling inaccuracy. Researchers have investigated whether the robustness carries on to the controller’s digital implementation, mostly looking at how the controller reacts to either communication or computational problems. Communication problems are typically modelled using random variables (i.e., estimating the probability that a fault will occur during a transmission), while computational problems are modelled using deterministic guarantees on the number of deadlines that the control task has to meet. These fault models allow the engineer to both design robust controllers and assess the controllers’ behaviour in the presence of isolated faults. Despite being very relevant for the real-world implementations of control system, the question of what happens when these faults occur simultaneously does not yet have a proper answer. In this paper, we answer this question in the stochastic setting, using the theory of Markov Jump Linear Systems to provide stability contracts with almost sure guarantees of convergence. For linear time-invariant Markov jump linear systems, mean square stability implies almost sure convergence – a property that is central to our investigation. Our research primarily emphasises the validation of this property for closed-loop systems that are subject to packet losses and computational overruns, potentially occurring simultaneously. We apply our method to two case studies from the recent literature and show their robustness to a comprehensive set of faults. We employ closed-loop system simulations to empirically derive performance metrics that elucidate the quality of the controller implementation, such as the system settling time and the integral absolute error.
48

KLASEN, MICHAEL. "CALCULATING TWO- AND THREE-BODY DECAYS WITH FeynArts AND FormCalc". International Journal of Modern Physics C 14, n. 09 (novembre 2003): 1273–78. http://dx.doi.org/10.1142/s012918310300539x.

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The Feynman diagram generator FeynArts and the computer algebra program FormCalc allow for an automatic computation of 2→2 and 2→3 scattering processes in High Energy Physics. We have extended this package by four new kinematical routines and adapted one existing routine in order to accomodate also two- and three-body decays of massive particles. This makes it possible to compute automatically two- and three-body particle decay widths and decay energy distributions as well as resonant particle production within the Standard Model and the Minimal Supersymmetric Standard Model at the tree- and loop-level. The use of the program is illustrated with three standard examples: [Formula: see text], [Formula: see text], and [Formula: see text].
49

Rui, Yu. "Research on Identification of Vehicle Steering Angle". Applied Mechanics and Materials 608-609 (ottobre 2014): 787–93. http://dx.doi.org/10.4028/www.scientific.net/amm.608-609.787.

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Based on Radial Basis Function neural networks , a method of identifying vehicle steering angle is proposed for further investigation of the vehicle handling inverse dynamics. According to the simulation results of a two-degree-freedom closed-loop system and the test of double lane change maneuver, the mapping relationship between vehicle yaw velocity, lateral acceleration and steering angle can be found. The identification results show that the method is not only feasible, but also with high accuracy, little computation requirement and good stability.
50

Liu, Feng, Yihui Xia, Lv Yang e Bin Zhang. "Feedback Linearization Sliding Mode Control Strategy for Three-Phase Voltage PWM Rectifier Based on New Variable Speed Reaching Law". Electronics 13, n. 5 (1 marzo 2024): 960. http://dx.doi.org/10.3390/electronics13050960.

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Three-phase voltage PWM rectifier is a multivariable, strong coupling, nonlinear multi-input and multi-output system. In the design of rectifier control systems, with PI control it is difficult to achieve the ideal control effect, the dynamic performance is poor, and the parameter computation is complex. Moreover, the traditional sliding mode control voltage outer loop suffers from the problem of chattering, which is difficult to solve. Responding to the above issues, a new type of variable speed reaching law is proposed, which is applied to the voltage outer loop sliding mode control, while the feedback linearization principle is introduced to the current inner loop, and a new type of double closed-loop sliding mode control system is obtained by applying the two theories to the design of the sliding mode controller. A simulation model is established in MATLAB/Simulink to compare the PI control, the SMC control and the V-SMC control strategy proposed in this paper (voltage outer loop V-SMC current inner loop FLC-SMC control), and the simulation results show that the rectifier under the new dual-closed-loop sliding mode control strategy has the advantages of good dynamic performance, strong robustness and strong anti-interference ability. At the same time, compared with the traditional sliding mode control strategy, the vibration suppression effect under the proposed control strategy is obvious. Finally, a 10 kW rectifier control system is built on a semi-physical hardware-in-the-loop experimental platform to further verify the correctness and superiority of the proposed control strategy.

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