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Estimating the computation accuracy of Mixed Waves in the Ocean on the Basis of Present-Day Numerical Models

RUSSIAN METEOROLOGY AND HYDROLOGY 2011年第10期36卷 669-676页

作者： Nesterov, E. S. Abuzyarov, Z. K. Grigor'eva, G. A. Davidan, I. N. Dymov, V. I. Pasechnik, T. A. Hydrometeorol Res Ctr Russian Federat Moscow 123242 Russia Zubov State Oceanog Inst St Petersburg Div St Petersburg 199026 Russia Arctic & Antarctic Res Inst St Petersburg 199397 Russia

An estimate of the computation accuracy of wind waves is obtained on the basis of three mathematical models used for the diagnosis and forecast of wind waves at the Hydrometcenter of Russia, US National Weather Service, and European Centre for Medium-Range Weather Forecasts. The accuracy estimation was carried out for the whole year 2006 by means of the comparison of model computations based on different wind fields with hourly instrumental observations of waves at 16 buoys in the North Atlantic. The computation accuracy was estimated on the basis of six statistical characteristics. Besides, the estimates for various wave height ranges for months and seasons of the year are made for all buoys and grouped into three geographical areas: the coasts of the United States, Canada, and Great Britain. The essential differences are revealed in the accuracy of model-based computation of waves in the areas of the ocean with different wind wave regimes, in different seasons of the year, and within various wave height ranges. The obtained results indicate the necessity to improve the present-day methods of diagnosis and forecast of wind waves.

关键词： computation accuracy oceans Wind fields seasons of the year Wind waves Wave Height Basis Buoys

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Enhanced computational Efficiency and accuracy of Discrete-Time PID-DPWM Equation

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IEEE ACCESS 2025年 13卷 62288-62305页

作者： Kim, Eungnam Choi, Jin-Young Korea Univ Dept Comp Sci Seoul 02841 South Korea Korea Univ Grad Sch Informat Secur Seoul 02841 South Korea

The technique of using the duty cycle output of a proportional integral derivative controller as the input for a count-based digital pulse width modulation module to process digital PWM signals is widely applied across various industrial fields, including automotive, power control, and motor control. This paper refers to this approach as the classic PID-DPWM equation. Classic PID-DPWM equations have been studied with the perspective that the raw-data measured input, and the integer-value duty value are integers. This study presents the improved PID-DPWM equations that start with the initial data scaling equation and perform integer-based computations and one floating-point operation. Consequently, the proposed equations become equivalent to the classic PID-PWM equations, enhancing computational efficiency and accuracy. The enhancement in computational efficiency was verified mathematically, and the improvement in accuracy was validated using performance index tests. A validation test of a closed-loop system in MATLAB/Simulink demonstrated that the improved standard PID-DPWM equation outperformed the classic standard PID-DPWM equation, achieving improvements in performance indices (ISE = 0.0001%, IAE = 0.27%, IE = 0.035%, ITSE = 0.012%, and ITAE = 2.85%). Furthermore, the improved difference PID-DPWM equation demonstrates further improvements over the classic difference PID-DPWM equation, achieving improvements in performance indices (ISE = 0.98%, IAE = 4.79%, IE = 15.87%, ITSE = 4.25%, and ITAE = 26.89%). Overall, the improved standard PID-DPWM equation exhibited enhanced performance in ISE, IAE, and ITAE, whereas the improved difference PID-DPWM equation exhibited superior performance in IE and ITSE.

关键词： Mathematical models Standards accuracy computational efficiency Software Real-time systems Hardware Control systems Pulse width modulation Optimization computation accuracy computation speed DPWM PID software control

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New development of the turbulent Prandtl number models for the computation of film cooling effectiveness

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2011年第4期54卷 874-886页

作者： Liu, Cun-liang Zhu, Hui-ren Bai, Jiang-tao Northwestern Polytech Univ Sch Power & Energy Xian 710072 Peoples R China

This paper presents the new development on the turbulent Prandtl number distribution models which are used to improve the computation accuracy of film cooling effectiveness distribution in the frame of the isotropic turbulence models. In the new developed turbulent Prandtl number distribution models, the turbulent Prandtl number varies with some characteristic quantity of the film cooling to make the models applicable for more film cooling cases effectively. A new VTG-Pr-t model is developed for the computation of film cooling cases in which the wall is mainly influenced by the mixing layer region between the jet core and the mainstream. The Pr-t value in this model varies with dimensionless temperature gradient which is suggested to be the characteristic quantity of the mixing layer region. The VTG-Pr-t model has been used in the computations of long cylindrical hole film cooling, short cylindrical hole film cooling, compound angle cylindrical hole film cooling and expansion shaped hole film cooling in the present paper. And it is validated to be an effective and easy way to obtain accurate film cooling effectiveness distributions for this kind of film cooling. But for the kind of film cooling, in which the wall is mainly influenced by the jet core region and the influence of heat diffusion in the mixing layer region on the cooling effectiveness is very small, the VTG-Pr-t model is disabled. Another turbulent Prandtl number distribution model, named VT-Pr-t model, is developed for this kind of film cooling in the present paper. The Pr-t value in this model varies with dimensionless temperature which is suggested to be the characteristic quantity of the jet core region. Good agreement between the computed and measured results is obtained through the use of VT-Pr-t model in the computation of converging slot hole film cooling. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.

关键词： Turbulent Prandtl number model Film cooling effectiveness computation accuracy Characteristic quantity Isotropic turbulence model

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Over-the-Air computation Based on Optimal Node Selection in Densely Deployed IoT Networks

Over-the-Air Computation Based on Optimal Node Selection in ...

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IEEE/CIC International Conference on Communications in China (ICCC)

作者： Wang, Ruofan Li, Xi Zhang, Heli Beijing Univ Posts & Telecommun Key Lab Universal Wireless Commun Minist Educ Beijing Peoples R China

ISBN: (纸本)9798350378412

Future intelligent Internet of things (IoT) networks will realize seamless connections of the physical world by deploying billions of IoT nodes for information collection and procession. For the densely deployed IoT scenarios, such as smart city, over-the-air computation (AirComp) is introduced as an efficient processing approach. By exploiting the superposition property of the wireless channels, AirComp can calculate various functions of the original data in the air. How to prolong the lifetime of the whole networks as well as to improve the computation results accuracy of AirComp, need further investigation. Thus, we propose an over-the-air computation strategy based on optimal node selection in densely deployed IoT networks, which can reduce computation error and improve network lifetime simultaneously. Specifically, we propose node suitability value to assess each IoT node from energy, channel state and coverage perspective, and elect the most suitable nodes to perform the AirComp task. To further optimize the computation accuracy, a mean-square error (MSE) minimization problem is established and solved by jointly optimising the beamforming vector and the transmit coefficient. In this process, block coordinate descent (BCD) and Karush-Kuhn-Tucker (KKT) method have been introduced to obtain closed-form solution for each variable. Simulation results are provided to show the benefit of the proposed strategy in terms of computation accuracy and average node lifetime.

关键词： Over-the-air computation (AirComp) Optimal node selection Node suitability value computation accuracy Node lifetime

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Single-Monitor Calibration for Multiple Microring Synapses

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ACS PHOTONICS 2024年第7期11卷 2570-2577页

作者： Liu, Xinyu Zhang, Wenkai Cheng, Junwei Zhou, Hailong Dong, Jianji Huazhong Univ Sci & Technol Wuhan Natl Lab Optoelect Wuhan 430074 Peoples R China

Microrings hold significant applications in optical analog computing and can be arranged in an array to establish photonic weight banks for matrix-vector multiplication. However, microrings face challenges in precision and stability due to the sensitivity to internal thermal crosstalk and environmental disturbances;thus, massive monitors (usually bulky instruments) are needed to calibrate weights of massive microrings. Until now, multiple microring synapses had not been simultaneously calibrated with only one monitor. To address this issue, we propose a single-monitoring scheme to simultaneously calibrate multiple microring weights. In the experiment, we demonstrate the ability to simultaneously calibrate weights of 16 microrings with excellent immunity to environmental fluctuations and internal crosstalk. Furthermore, the scalability of this scheme offers a novel outlook for enhancing the precision of large-scale microring-based systems while simultaneously mitigating the equipment demands associated with calibration.

关键词： integrated optics optical computing opticalneural synapse computation accuracy self-calibration

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Propagation and diffraction of truncated Gaussian beams

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2001年第3期18卷 546-556页

作者： Nourrit, V de la Tocnaye, JL Chanclou, P Ecole Natl Super Telecommun Dept Opt Brest France

The Fresnel diffraction of a truncated Gaussian beam is investigated in detail. Our aim is to provide usable analytical expressions of the diffracted held with respect to the variation of propagation and diffraction parameters. Particular attention is paid to the determination of a trade-off between computing accuracy and simplicity. An illustration of the use of the various expressions describing the beam diffraction and propagation is given for the case of mode coupling in a single-made fiber. (C) 2001 Optical Society of America.

关键词： America Gaussian beams mode coupling diffraction computation accuracy Fresnel diffraction

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NUMERICAL-METHODS FOR COMPUTING INTERFACIAL MEAN-CURVATURE

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computationAL MATERIALS SCIENCE 1995年第2期4卷 103-116页

作者： BULLARD, JW GARBOCZI, EJ CARTER, WC FULLER, ER NATL INST STAND & TECHNOL DIV BLDG MATGAITHERSBURGMD 20899 NATL INST STAND & TECHNOL DIV CERAMGAITHERSBURGMD 20899

A procedure is described for computing the mean curvature along condensed phase interfaces in two or three dimensions, without knowledge of the spatial derivatives of the interface. For any point P on the interface, the method consists of computing the portion of volume enclosed by a small template sphere, centered on P, that lies on one side of the interface. That portion of the template volume is shown to be linear in the mean curvature of the surface, relative to the phase lying on the opposite side of the interface, to within terms that can usually be made negligible. An analogous procedure is described in two dimensions. Application of the procedure to compute the mean curvature along a digitized surface is demonstrated. A burning algorithm can be included to improve computational accuracy for interfaces having sharp curvature fluctuations. A minor extension of the method allows computation of the orientation of an interfacial element relative to a fixed reference frame.

关键词： computation accuracy Numerical methods Interfaces Phase interfaces mean curvature Interface REFERENCE FRAMES

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Enhancing estimation accuracy of daily maximum, minimum, and mean air temperature using spatio-temporal ground-based and remote-sensing data in southern Iran

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INTERNATIONAL JOURNAL OF REMOTE SENSING 2018年第19期39卷 6316-6339页

作者： Didari, Shohreh Zand-Parsa, Shahrokh Shiraz Univ Sch Agr Water Engn Dept Shiraz Iran

In this research, a model was proposed for improving the estimation of air temperature (T-a), which enhanced computation accuracy by combining remote sensing, station data, and spatio-temporal interpolation methods. Stepwise linear regression model was used to find the relationship between daily mean, maximum, and minimum air temperature (T-mean, T-max, and T-min, respectively) with daytime and night-time land surface temperature (LST), normalized difference vegetation index (NDVI) from the Moderate Resolution Imaging Spectroradiometer sensor, elevation, geometric temperature (T-geom, as a function of the day of the year and latitude), and solar radiation (R-s). Measured T-a from 75 stations in the Fars province in southern Iran were used during 2003-2012. The results of stepwise linear regression showed that among the considered variables daytime and night-time LST, NDVI, T-geom, R-s, and elevation were significant in the final model. For increasing the accuracy of estimation, four interpolation methods were considered and analysed for the residual errors of multiple linear regression model consisting regression kriging, spatio-temporal regression kriging (STRK), regression inverse distance weighting, and spatio-temporal regression inverse distance weighting (STRIDW). The result showed that the STRIDW method had the best accuracy among the considered methods and a significant improvement in the accuracy was achieved with this method comparing to the others. The accuracy of estimations was less than 2 degrees C for T-max, T-min, and T-mean (root mean square error = 1.6 degrees C, 1.84 degrees C, and 1.43 degrees C, respectively) for the validation year (2012). Finally, using the proposed models, it was possible to estimate daily air temperatures in the Fars province with 1 km resolution, which is higher than methods that used purely station-based or purely remote-sensing data.

关键词： computation accuracy Linear Regression remote-sensing data air temperature ROOT-MEAN-SQUARE ERRORS total maximum daily load inverse distance Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index

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Studying pulsed operation modes of irregular coaxial lines with combined distributed and lumped irregularities

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JOURNAL OF COMMUNICATIONS TECHNOLOGY AND ELECTRONICS 2005年第1期50卷 27-32页

作者： Koroza, VI Golikov, MN

The problem of propagation and transformation of electromagnetic pulses with the TEM initial structure in irregular coaxial transmission lines containing combinations of distributed and lumped irregularities is formulated, and a numerical algorithm for solving this problem is presented. The problem is formulated and solved in the time domain using nonstationary waveguide equations. Numerical examples are presented for lines containing both distributed smooth irregularities extended along the line axis and various lumped irregularities. The attainability of high calculation accuracy (with errors of similar to0.03% and lower) and control over calculation error is demonstrated.

关键词： electromagnetic pulses irregularities TIME-DOMAIN coaxial cables pulsed operation calculation error Distribute operation mode computation accuracy coaxial transmission line

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Finite difference calculations of electro-magnetic fields in arbitrary curvilinear coordinates for coaxial microwave plasma sources

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PLASMA SOURCES SCIENCE & TECHNOLOGY 1999年第2期8卷 325-331页

作者： Bilgic, AM Garloff, K Voges, E Univ Dortmund Lehrstuhl Hochfrequenztech D-44221 Dortmund Germany

We present a finite difference frequency domain (FDFD) algorithm for the vector wave equation. Employing covariant formulations, arbitrary curvilinear, non-orthogonal computational grids are mapped onto equidistant Cartesian coordinates. This provides an intrinsic method for a local increase of computational accuracy and application of standard finite difference expressions. As an example this technique is applied to the microwave plasma torch (MPT). It is shown that there is a high held plasma generating region on top of the inner conductor. The interior of this region is of comparably low electrical field strength and supposed to be responsible for the hollow structure of the plasma observed in this type of plasma source.

关键词： Hollow Structures plasma sources MICROWAVE Spherical coordinates Finite differences Wave equation Coaxial magnetic field Arbitrary Plasmas computation accuracy ELECTROMAGNETIC

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