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10th Annual Conference of the Prognostics and Health Management Society, PHM 2018

作者： Cheung, Wang-Chi Zhang, Weiwen Liu, Yong Yang, Feng Rick-Siow-Mong, Goh Institute of High Performance Computing Agency for Science Technology and Research Singapore

ISBN: (纸本)9781936263295

Recent studies have revealed the success of data-driven machine health monitoring, which motivates the use of machine learning models in machine health prognostic tasks. While the machine learning approach to health monitoring is gaining importance, the construction of machine learning models is often impeded by the difficulty in choosing the underlying hyper-parameter configuration (HP-config), which governs the construction of the machine learning model. While an effective choice of HP-config can be achieved with human effort, such an effort is often time consuming and requires domain knowledge. In this paper, we consider the use of Bayesian optimization algorithms, which automate an effective choice of HP-config by solving the associated hyperparameter optimization problem. Numerical experiments on the data from PHM 2016 Data Challenge demonstrate the salience of the proposed automatic framework, and exhibit improvement over default HP-configs in standard machine learning packages or chosen by a human agent. © 2018 Prognostics and Health Management Society. All rights reserved.

关键词： Machine learning

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Cfd study of the wind load on a lng carrier 31st

Cfd study of the wind load on a lng carrier

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31st International Ocean and Polar Engineering Conference, ISOPE 2021

作者： Zhang, Baili Dao, My Ha Xing, Xiuqing Lou, Jing Institute of High Performance Computing Agency for Science Technology and Research Singapore

ISBN: (纸本)9781880653821

Accurate prediction of wind load is very critical to the safety and efficiency of ship operations, such as maneuvering, berthing, offloading or dynamic positioning. In this study, we have conducted detailed CFD studies of wind flow over a simplified LNG carrier GALEA at model scale of 1:400, including mesh types, mesh independence, turbulence models as well as impact of different wind profiles. The simulations are carried out at the wind velocity of 10m/s, for all wind headings between 0 to 360 degrees with a step of 10 degrees. The calculated wind loads agree well with numerical prediction and experimental measurements reported in literature. © 2021 by the International Society of Offshore and Polar Engineers (ISOPE).

关键词： Wind stress

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Bulk Superconductivity in Pressurized Trilayer Nickelate Pr4Ni3O10 Single Crystals

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Physical Review X 2025年第2期15卷 021008-021008页

作者： Enkang Zhang Di Peng Yinghao Zhu Lixing Chen Bingkun Cui Xingya Wang Wenbin Wang Qiaoshi Zeng Jun Zhao State Key Laboratory of Surface Physics and Department of Physics Fudan University Shanghai 200433 China Shanghai Research Center for Quantum Sciences Shanghai 201315 China Shanghai Key Laboratory of Material Frontiers Research in Extreme Environments (MFree) Shanghai Advanced Research in Physical Sciences (SHARPS) Shanghai 201203 China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research Institute Chinese Academy of Sciences Shanghai 201204 China Institute of Nanoelectronics and Quantum Computing Fudan University Shanghai 200433 China Center for High Pressure Science and Technology Advanced Research Shanghai 201203 China Hefei National Laboratory Hefei 230088 China

The discovery of superconductivity in pressurized bilayer and trilayer nickelates has generated significant interest. However, their superconducting properties are often dependent on sample quality and pressure conditions, complicating the interpretation of the underlying physics. Finding new systems with optimized bulk superconducting properties is therefore important for advancing our understanding of these materials. Unlike cuprates, where trilayer compounds typically exhibit the highest transition temperature (Tc), the bilayer nickelate La3Ni2O7 has thus far outperformed the trilayer La4Ni3O10 in reported Tc. Whether the trilayer nickelates have achieved the optimal Tc remains unclear, with various scenarios suggesting different possibilities. Here, we report the discovery of bulk superconductivity in pressurized Pr4Ni3O10 single crystals, achieving a maximum onset Tc of 40.5 K at 80.1 GPa, significantly exceeding the 30 K observed in La4Ni3O10. The bulk nature of superconductivity is confirmed by zero resistance and a strong diamagnetic response below Tc, with a superconducting volume fraction exceeding 80%. These findings establish trilayer nickelates as genuine bulk high-temperature superconductors, provide new insights into the mechanisms driving superconductivity, and point to a promising route toward further enhancing superconducting properties in nickelates.

关键词： Single crystals

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An introduction to the gilgamesh PIM architecture 7

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7th European Conference on Parallel computing, Euro-Par 2001

作者： Sterling, Thomas Center for Advanced Computing Research California Institute of Technology and High Performance Computing Group NASA Jet Propulsion Laboratory United States

ISBN: (纸本)3540424954

Throughout the history of computer implementation, the technologies employed for logic to build ALUs and the technologies employed to realize high speed and high-density storage for main memory have been disparate, requiring different fabrication techniques. This was certainly true at the beginning of the era of electronic digital computers where logic was constructed from vacuum tubes and main memory was produced by wired arrays of magnetic cores. But it is also true with today’s conventional computing systems. Yes, both logic and memory are now fabricated with semiconductors. But the fabrication processes are quite different as they are optimized for very different functionality. CMOS logic pushes speed of active components while DRAM storage maximizes densityof passive capacitive bit cells. As a consequence of this technology disparity between the means of achieving distinct capabilities of memory and logic, computer architecture has been constrained by the separation of logical units and main memory units. The von Neumann bottleneck is the communication’s channel choke point between CPUs and main memory resulting from the separation imposed by these distinct device types. Much of modern microprocessor architecture is driven by the resulting data transfer throughput and latency of access due to this separation as well as the very different clock speeds involved. More subtle but of equal importance are the limitations imposed on the diversity of possible structures that might be explored and achieved were it feasible to bridge this gap and intertwine memory and logic.

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Smoothed Online Convex Optimization in high Dimensions via Online Balanced Descent 31

Smoothed Online Convex Optimization in High Dimensions via O...

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31st Annual Conference on Learning Theory, COLT 2018

作者： Chen, Niangjun Goel, Gautam Wierman, Adam Institute of High Performance Computing Singapore California Institute of Technology United States

We study smoothed online convex optimization, a version of online convex optimization where the learner incurs a penalty for changing her actions between rounds. Given a Ω(√d) lower bound on the competitive ratio of any online algorithm, where d is the dimension of the action space, we ask under what conditions this bound can be beaten. We introduce a novel algorithmic framework for this problem, Online Balanced Descent (OBD), which works by iteratively projecting the previous point onto a carefully chosen level set of the current cost function so as to balance the switching costs and hitting costs. We demonstrate the generality of the OBD framework by showing how, with different choices of "balance," OBD can improve upon state-of-the-art performance guarantees for both competitive ratio and regret;in particular, OBD is the first algorithm to achieve a dimension-free competitive ratio, 3 + O(1/α), for locally polyhedral costs, where α measures the "steepness" of the costs. We also prove bounds on the dynamic regret of OBD when the balance is performed in the dual space that are dimension-free and imply that OBD has sublinear static regret. © 2018 N. Chen, G. Goel & A. Wierman.

关键词： Cost functions

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AN APPROXIMATE RIEMANN SOLVER FOR IDEAL MAGNETOHYDRODYNAMICS

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JOURNAL OF COMPUTATIONAL PHYSICS 1994年第2期111卷 354-372页

作者： DAI, WL WOODWARD, PR School of Physics and Astronomy Supercomputer Institute Army High Performance Computing Research Center University of Minnesota Minneapolis/St. Paul Minnesota 55415

To construct numerical schemes of he Godunov type for solving magnetohydrodynamical (MHD) problems, an approximate method of solving the MHD Riemann problem is required in order to calculate the time-averaged fluxes at the interfaces of numerical zones, Such an MHD Riemann solver is presented here which treats all waves emanating from the initial discontinuity as themselves discontinuous. Thus shock jump conditions are used for rarefactions, which limits the applicability of this work to weak rarefactions, the case most important for computation. The solutions from our approximate MHD Riamnn solver consist of two fast waves (either shock or rarefaction) two rotational discontinuities, two rarefaction waves (either shock or rarefaction), and one contact discontinuity for a general MHD Riemann problem. In order to display rotational discontinuities, a three-component model is necessary. Only under very limited circumstances is there no rotational discontinuity involved and thus the two component approximation may be used in the MHD Riemann problem. The solutions of the MHD Riemann problem in the shock tube problem which generates the compound wave in the earlier work contain two fast rarefaction waves, two slow shocks, one contact discontinuity, and one rotational discontinuity in our formalism. (C) 1994 Academic Press, Inc.

关键词： Numerical methods

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Quark and Gluon Momentum Fractions in the Pion and in the Kaon

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Physical Review Letters 2025年第13期134卷 131902-131902页

作者： Constantia Alexandrou Simone Bacchio Martha Constantinou Joseph Delmar Jacob Finkenrath Bartosz Kostrzewa Marcus Petschlies Luis Alberto Rodriguez Chacon Gregoris Spanoudes Department of Physics University of Cyprus Nicosia Cyprus Computation-based Science and Technology Research Center The Cyprus Institute Nicosia Cyprus Department of Physics Temple University Philadelphia Pennsylvania 19122–1801 USA Department of Physics Bergische Universität Wuppertal Gaußstraße 20 Wuppertal 42119 Germany High Performance Computing and Analytics Lab Rheinische Friedrich-Wilhelms-Universität Bonn Germany Helmholtz-Institut für Strahlen- und Kernphysik University of Bonn Germany Bethe Center for Theoretical Physics University of Bonn Germany Department of Physics and Earth Science University of Ferrara & INFN Via Saragat 1 44122 Ferrara Italy

We present the full decomposition of the momentum fraction carried by quarks and gluons in the pion and the kaon. We employ three gauge ensembles generated with Nf=2+1+1 Wilson twisted-mass clover-improved fermions at the physical quark masses. For both mesons we perform a continuum extrapolation directly at the physical pion mass, which allows us to determine for the first time the momentum decomposition at the physical point. We find that the total momentum fraction carried by quarks is 0.575(79) and 0.683(50) and by gluons 0.402(53) and 0.422(67) in the pion and in the kaon, respectively, in the MS¯ scheme and at the renormalization scale of 2 GeV. Having computed both the quark and gluon contributions in the continuum limit, we find that the momentum sum is 0.984(89) for the pion and 1.13(11) for the kaon, verifying the momentum sum rule.

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7-lump kinetic model for residual oil catalytic cracking

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1932-1941页

作者： XU Ou-guan SU Hong-ye MU Sheng-jing CHU Jian National Laboratory of lndustrial Control Technology Institute of Advanced Process Control Zhejiang University Hangzhou 310027 China Institute of High Performance Computing The Capricorn 117528 Singapore

In this paper a novel 7-lump kinetic model is proposed to describe residual oil catalytic cracking, in which coke is lumped separately for accurate prediction. The reactor block is modeled as a combination of an ideal pipe flow reactor (PFR) and a continuously stirred tank reactor (CSTR). Unit factors are designed to correct the deviation between model predictions and practical plant data and tuned by modified Levenberg-Marquardt algorithm. The parameters estimated are reliable and good agreement between the model predictions and plant observations is observed. The model helps us get good insight into the per- formance of an industrial riser reactor that would be useful for optimization of residual oil catalytic cracking.

关键词： Residua catalytic cracking (RCC) 7-lump kinetic model Unit factor

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A computational-intelligence-based optimization of agents' initial positions in land combat simulation

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自然科学进展(英文版) 2003年第8期13卷 620-625页

作者： WU Chunguo LIANG Yanchun GE Hongwei CAO Lijuan LEE Heow Pueh College of Computer Science and Technology Jilin University Changchun 130012 China Institute of High Performance Computing Singapore 117528 Singapore College of Mathematics Science Jilin University Changchun 130012 China Institute of High Performance Computing Singapore 117528 Singapore Institute of High Performance Computing Singapore 117528 Singapore Department of Mechanical Engineering National University of Singapore Singapore 119260 Singapore

The optimization of agents' initial properties enables agents to perform their assigned tasks more perfectly. This paper presents an optimizing method using the combination of radial basis function (RBF) neural network and genetic algorithm (GA). In the land combat simulation, the method can ensure that the agents optimized defeat the agents not optimized absolutely. Compared with the optimization based on support vector machines (SVM), the proposed method improves the efficiency more than twenty times, so it suits the cases where the speed as well as performance is required.

关键词： multi-agent system RBF neural network support vector machine land combat simulation genetic algorithm

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A TOOL PATH CORRECTION AND COMPRESSION ALGORITHM FOR FIVE-AXIS CNC MACHINING

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Journal of Systems Science & Complexity 2013年第5期26卷 799-816页

作者： GENG Cong YU Dong ZHENG Liaomo ZHANG Han WANG Feng University of Chinese Academy of Sciences Notional Engineering Research Center for High-End CNC Shenyang Institute of Computing TechnologyChinese Academy of Science

A novel approach is proposed for correcting command points and compressing discrete axis commands into a C2 continuous *** relationship between values of rotation angles and tool posture errors is firstly analyzed.A segmentation method based on values of rotation angles and lengths of adjacent points is then used to subdivide these command points into accuracy regions and smoothness *** tool center points generated by CAD/CAM system are usually lying in the space that is apart from the desired curve within a tolerance distance,and the corresponding tool orientation vector may change a lot while the trajectory length of the tool center point is quite small,directly machining with such points will lead to problems of coarse working shape and long machining time.A correction method for command points is implemented so that good processing effectiveness can be ***,the quintic spline is used for compressing discrete command points into a C2 continuous smooth *** machining experiment is finally conducted to demonstrate the effectiveness of the proposed algorithm.

关键词： Curve fitting five-axis CNC machining tool orientation vector tool path correction toolposture error.

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