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Effects of the Water-Cement Ratio and the Molding Temperature on the Hydration Heat of Cement
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作者 代金鹏 HE Jie +1 位作者 WANG Qicai LOU Xuyu 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2024年第4期990-998,共9页
The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and... The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and 0.45,and the molding temperature was specified at 10 and 20℃.The experimental results show that,as the water-binder ratio increases,the value of the second temperature peak on the temperature curve of the cement paste decreases,and the age at which the peak appears is delayed.The higher the water-cement ratio,the higher the hydration heat release in the early period of cement hydration,but this trend reverses in the late period.There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio,and this law can be observed at both molding temperatures.With the increase in the molding temperature,the age of the second temperature peak on the temperature curve of the cement paste will advance,but the temperature peak will decrease.The higher the molding temperature,the earlier the acceleration period of the cement hydration began,and the larger the hydration heat of the cement in the early stage,but the smaller the total heat in the late period.A subsection function calculation model of the hydration heat,which was based on the existing models,was proposed in order to predict the heat of the hydration of the concrete. 展开更多
关键词 semi-adiabatic calorimetry hydration heat water-cement ratio molding temperature MODELING
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Effects of Water-cement Ratio and Hydration Heat Regulating Materials on Hydration Process of Early-age Cementitious Materials
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作者 赵海涛 XIANG Yu +4 位作者 徐文 CHEN Xiaodong ZHU Yue WU Haotian LIU Shibin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第1期88-96,共9页
By means of low-field nuclear magnetic resonance(LF-NMR),the transverse relaxation time(T_(2))signals of physically bound water in cement paste were monitored to indicate water content change and characterize the earl... By means of low-field nuclear magnetic resonance(LF-NMR),the transverse relaxation time(T_(2))signals of physically bound water in cement paste were monitored to indicate water content change and characterize the early-age hydration process.With the curves of the T_(2)signals and hydration time obtained,the hydration process could be divided into four typical periods using the null points of the second derivative curve,and the influences of water-cement ratio(w/c)and hydration heat regulating materials(HHRM)on hydration process were analyzed.The experimental results showed that the hydration rate of pure cement paste in accelerated period presented a positive correlation with w/c.Compared to pure cement paste,the addition of HHRM extended all four periods,and led to a much faster hydration rate in initial period as well as a slower rate in accelerated period.Finally,according to the LFNMR test results,the early-age hydration model of cementitious materials was proposed considering w/c and HHRM content. 展开更多
关键词 HYDratioN water-cement ratio hydration heat regulating materials cementitious materials early age low-field nuclear magnetic resonance
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Generalized Likelihood Ratio Tests for Varying-Coefficient Models with Censored Data
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作者 Rong Jiang Wei-Min Qian 《Open Journal of Statistics》 2011年第1期19-23,共5页
In this paper, we extend the generalized likelihood ratio test to the varying-coefficient models with censored data. We investigate the asymptotic behavior of the proposed test and demonstrate that its limiting null d... In this paper, we extend the generalized likelihood ratio test to the varying-coefficient models with censored data. We investigate the asymptotic behavior of the proposed test and demonstrate that its limiting null distribution follows a distribution, with the scale constant and the number of degree of freedom being independent of nuisance parameters or functions, which is called the wilks phenomenon. Both simulated and real data examples are given to illustrate the performance of the testing approach. 展开更多
关键词 VARYING COEFFICIENT Model generalized LIKELIHOOD ratio Test Local Linear Method Wilks Phenomenon CENSORING
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Ultimate end bearing capacity of rock-socketed pile based on generalized nonlinear unified strength criterion 被引量:7
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作者 章敏 王星华 汪优 《Journal of Central South University》 SCIE EI CAS 2011年第1期208-215,共8页
In order to study the mechanism of bearing behavior at the tip of a pile embedded in rock, the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems w... In order to study the mechanism of bearing behavior at the tip of a pile embedded in rock, the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems which govern the stress field were applied to derive the ultimate end beating capacity based on some reasonable hypothesis and failure plane model. Both numerical simulation and test results were compared with the theoretic solution. The results show good consistency with each other and verify the validity of the present approach. The depth effect with respective to embedment ratio and other influence factors like geological strength index, intermediate principal stress, overburden factor, and damage on end bearing capacity were discussed in the analytical solution. The results show that the proposed yield criterion can be much better for investigating the ultimate end bearing performance of rock-socketed pile. The end bearing capacity increases with embedment ratio and the increasing degree is influenced intensely by the above parameters. Furthermore, ignoring intermediate stress effect would underestimate the strength properties of the rock material and lead to a very conservative estimation value. 展开更多
关键词 rock-socketed pile generalized nonlinear unified strength criterion slip line principle embedment ratio damage endbearing capacity
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Sensitivity and effect of key operational parameters on performance of a dual-cylinder free-piston engine generator 被引量:1
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作者 ZHANG Zhi-yuan FENG Hui-hua +1 位作者 JIA Bo-ru ZUO Zheng-xing 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第7期2101-2111,共11页
The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio o... The free-piston engine generator(FPEG)is regarded as the next generation of energy conversion system which may replace traditional engines in the future.The effect of key operational parameters like excess air ratio of input mixture and ignition position on the engine performance of a dual-cylinder FPEG was investigated,and their sensitivity was analyzed in this paper.The operating compression ratio of the system is susceptible to changes in excess air ratio and ignition position.At the same time,it decreases from 15.8 to 6.6 when excess air ratio increases from 0.85 to 1.15,but it increases from 6.1 to 13.3 as ignition position increases from 15 mm to 20 mm.The operating frequency and indicated power are more sensitive to changes in excess air ratio than ignition position.But it is the opposite for the indicated thermal efficiency and friction loss.Excess air ratio and ignition position have a quite similar influence on heat transfer.Therefore,from the perspective of system operation and performance,it is preferable to keep excess air coefficient slightly below 1.0.In contrast,when selecting ignition position,it is of great importance to comprehensively consider the risk of structural damage caused by the increase in the compression ratio and in-cylinder gas pressure. 展开更多
关键词 free piston engine generator excess air ratio ignition position operation characteristics sensitivity analysis thermal efficiency
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Effect of Inert Gases on Ozone Generation Using Dielectric Barrier Discharge in Oxygen 被引量:2
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作者 WEI Linsheng TAN Zhihong 《高电压技术》 EI CAS CSCD 北大核心 2012年第7期1608-1612,共5页
关键词 惰性气体 电子能量 臭氧 电离能
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Saturation Ion Current Densities in Inductively Coupled Hydrogen Plasma Produced by Large-Power Radio Frequency Generator
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作者 WANG Songbai LEI Guangjiu +3 位作者 BI Zhenhua H. GHOMI YANG Size LIU Dongping 《Plasma Science and Technology》 SCIE EI CAS CSCD 2016年第9期907-911,共5页
An experimental investigation of the saturation ion current densities (Jions) in hydrogen inductively coupled plasma (ICP) produced by a large-power (2-32 kW) radio frequency (RF) generator is reported, then s... An experimental investigation of the saturation ion current densities (Jions) in hydrogen inductively coupled plasma (ICP) produced by a large-power (2-32 kW) radio frequency (RF) generator is reported, then some reasonable explanations are given out. With the increase of RF power, the experimental results show three stages: in the first stage (2-14 kW), the electron temperature will rise with the increase of RF power in the ICP, thus, the Jions increases continually as the electron temperature rises in the ICP. In the second stage (14 20 kW), as some H- ions lead to the mutual neutralization (MN), the slope of Jio^s variation firstly decreases then increases. In the third stage (20-32 kW), both the electronic detachment (ED) and the associative detachment (AD) in the ICP result in the destruction of H- ions, therefore, the increased amplitude of the Jions in the third stage is weaker than the one in the first stage. In addition, with the equivalent transformer model, we successfully Explain that the Jions at different radial locations in ICP has the same rule. Finally, it is found that the Jions has nothing to do with the outer/inner puffing gas pressure ratio, which is attributed to the high-speed movement of hydrogen molecules. 展开更多
关键词 saturation ion current densities large-power RF generator outer/innerpuffing gas pressure ratio H- ion transformer model
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Pressure-Controlled Inverse Ratio Ventilation during General Anesthesia for Open Abdominal Surgery Improves Postoperative Pulmonary Function 被引量:3
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作者 Xiuqin Wang Peimin Wang +2 位作者 Kaiguo Wang Tao Jiang Zan Xu 《Journal of Biomedical Science and Engineering》 2016年第1期17-24,共8页
Background: Studies have shown that pressure-controlled ventilation improves alveolar gas distribution. And inverse ratio ventilation has advantages of improving oxygenation in acute respiratory distress syndrome (ARD... Background: Studies have shown that pressure-controlled ventilation improves alveolar gas distribution. And inverse ratio ventilation has advantages of improving oxygenation in acute respiratory distress syndrome (ARDS) patients. However, the effects that pressure-controlled inverse ration ventilation in patients undergoes endotracheal intubation general anesthesia have not been assessed. Objective: To investigate whether pressure-controlled inverse ratio ventilation (PIV) would improve ventilatory and oxygenation parameters as well as lung function compared to conventional ventilation in patients undergoing open abdominal surgery. Interventions: In the conventional ventilation (CV) group, the ventilation strategy involved zero end-expiratory pressure and volume-controlled ventilation. In the pressure-controlled inverse ratio ventilation (PIV) group, the strategy involved P high starting at 7 cm H<sub>2</sub>O, P low starting at 4 cm H<sub>2</sub>O, T high at 4 s, T low at 2 s, and an inspiratory-to-expiratory time ratio of 2:1. The ΔP value was adjusted according to VT. Pressure levels were increased by 2 cm H<sub>2</sub>O until a maximal V<sub>T</sub> was observed. Inspired oxygen fraction (FIO<sub>2</sub>) was 1.0 and tidal volume (V<sub>T</sub>) was 6 mL/kg in both groups. Main Outcome Measures: The primary outcome is pulmonary function tests. Hemodynamic, ventilatory and oxygenation parameters were measured;visual analog scale (VAS) scores, and nausea and vomiting scores were also measured. Results: The PIV group tolerated pressure-controlled inverse ratio ventilation without significant hemodynamic instability. Mean airway pressure and static compliance were significantly higher in the PIV group than those in CV group (P P 2 h was well tolerated and improved respiratory compliance and lung function on the first postoperative day. 展开更多
关键词 Inverse ratio Ventilation Conventional Ventilation general Anesthesia Lung Function
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Research on Virtual DC Generator-Based Control Strategy of DCMicrogrid with Photovoltaic and Energy Storage 被引量:1
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作者 Feng Zhao Chengrui Xiao +1 位作者 Xiaoqiang Chen Ying Wang 《Energy Engineering》 EI 2023年第6期1353-1370,共18页
With the penetration of a large number of photovoltaic power generation units and power electronic converters,the DC microgrid shows low inertia characteristics,which might affect the stable operation of the microgrid... With the penetration of a large number of photovoltaic power generation units and power electronic converters,the DC microgrid shows low inertia characteristics,which might affect the stable operation of the microgrid in extreme cases.In order to enhance the“flexible features”of the interface converter connected to the DC bus,a control strategy of DCmicrogrid with photovoltaic and energy storage based on the virtual DC generator(VDCG)is proposed in this paper.The interface converters of the photovoltaic power generation system and the energy storage system simulates the inertia and damping characteristics of the DC generator to improve the stability of the DC bus voltage.The impedance ratio of DC microgrid was obtained by establishing the small-signal model of photovoltaic power generation system and energy storage system,and the Nyquist curves was applied to analyze the small-signal stability of the system.Finally,the simulation results were verified with MATLAB/Simulink.The results show that the proposed control strategy can slow down the fluctuation of bus voltage under the conditions of photovoltaic power fluctuation and load mutation,thus enhancing the system stability. 展开更多
关键词 DC microgrid with photovoltaic and energy storage virtual DC generator the low inertia characteristics smallsignal model impedance ratio
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A Study of Superconducting La<sub>2</sub>CuO<sub>4</sub>via Generalized BCS Equations Incorporating Chemical Potential
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作者 G. P. Malik V. S. Varma 《World Journal of Condensed Matter Physics》 2015年第3期148-159,共12页
We address the Tc (s) and multiple gaps of La2CuO4 (LCO) via generalized BCS equations incorporating chemical potential. Appealing to the structure of the unit cell of LCO, which comprises sub- lattices with LaO and O... We address the Tc (s) and multiple gaps of La2CuO4 (LCO) via generalized BCS equations incorporating chemical potential. Appealing to the structure of the unit cell of LCO, which comprises sub- lattices with LaO and OLa layers and brings into play two Debye temperatures, the concept of itinerancy of electrons, and an insight provided by Tacon et al.’s recent experimental work concerned with YBa2Cu3O6.6 which reveals that very large electron-phonon coupling can occur in a very narrow region of phonon wavelengths, we are enabled to account for all values of its gap-to-Tc ratio (2Δ0/kBTc), i.e., 4.3, 7.1, ≈8 and 9.3, which were reported by Bednorz and Müller in their Nobel lecture. Our study predicts carrier concentrations corresponding to these gap values to lie in the range 1.3 × 1021 - 5.6 × 1021 cm-3, and values of 0.27 - 0.29 and 1.12 for the gap-to-Tc ratios of the smaller gaps. 展开更多
关键词 generalized BCS EQUATIONS Chemical Potential Two-Phonon Exchange Mechanism Structure of the Unit Cell of LCO Gap-to-Tc ratio Effective Mass of Electrons Number Densities of Charge Carriers
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An Enhanced Automated Signature Generation Algorithm for Polymorphic Malware Detection
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作者 Ke Tang Ming-Tian Zhou Zhi-Hong Zuo 《Journal of Electronic Science and Technology》 CAS 2010年第2期114-121,共8页
Polymorphic malware is a secure menace for application of computer network systems because hacker can evade detection and launch stealthy attacks. In this paper, a novel enhanced automated signature generation (EASG... Polymorphic malware is a secure menace for application of computer network systems because hacker can evade detection and launch stealthy attacks. In this paper, a novel enhanced automated signature generation (EASG) algorithm to detect polymorphic malware is proposed. The EASG algorithm is composed of enhanced-expectation maximum algorithm and enhanced K-means clustering algorithm. In EASG algorithm, the fixed threshold value is replaced by the decision threshold of interval area. The false positive ratio can be controlled at low level, and the iterative operations and the execution time are effectively reduced. Moreover, the centroid updating is realized by application of similarity metric of Mahalanobis distance and incremental learning. Different malware group families are partitioned by the centroid updating. 展开更多
关键词 Index Terms -Entropy false positive ratio Mahalanobis distance polymorphie malware signature generation.
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A high resolution inversion method for fluid factor with dynamic dryrock V_(P)/V_(S) ratio squared
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作者 Lin Zhou Jian-Ping Liao +3 位作者 Xing-Ye Liu Pu Wang Ya-Nan Guo Jing-Ye Li 《Petroleum Science》 SCIE EI CSCD 2023年第5期2822-2834,共13页
As an important indicator parameter of fluid identification,fluid factor has always been a concern for scholars.However,when predicting Russell fluid factor or effective pore-fluid bulk modulus,it is necessary to intr... As an important indicator parameter of fluid identification,fluid factor has always been a concern for scholars.However,when predicting Russell fluid factor or effective pore-fluid bulk modulus,it is necessary to introduce a new rock skeleton parameter which is the dry-rock VP/VS ratio squared(DVRS).In the process of fluid factor calculation or inversion,the existing methods take this parameter as a static constant,which has been estimated in advance,and then apply it to the fluid factor calculation and inversion.The fluid identification analysis based on a portion of the Marmousi 2 model and numerical forward modeling test show that,taking the DVRS as a static constant will limit the identification ability of fluid factor and reduce the inversion accuracy.To solve the above problems,we proposed a new method to regard the DVRS as a dynamic variable varying with depth and lithology for the first time,then apply it to fluid factor calculation and inversion.Firstly,the exact Zoeppritz equations are rewritten into a new form containing the fluid factor and DVRS of upper and lower layers.Next,the new equations are applied to the four parameters simultaneous inversion based on the generalized nonlinear inversion(GNI)method.The testing results on a portion of the Marmousi 2 model and field data show that dynamic DVRS can significantly improve the fluid factor identification ability,effectively suppress illusion.Both synthetic and filed data tests also demonstrate that the GNI method based on Bayesian deterministic inversion(BDI)theory can successfully solve the above four parameter simultaneous inversion problem,and taking the dynamic DVRS as a target inversion parameter can effectively improve the inversion accuracy of fluid factor.All these results completely verified the feasibility and effectiveness of the proposed method. 展开更多
关键词 Fluid factor Dry-rock V_(P)/V_(S)ratio squared(DVRS) Dynamic variable Multiple parameters simultaneous inversion generalized nonlinear inversion(GNI)
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Power Ratio Gain Technique and General Integral Control
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作者 Baishun Liu 《Applied Mathematics》 2015年第4期663-669,共7页
In conjunction with general integral control, and synthesizing Singular perturbation and Equal ratio gain techniques, this paper proposes a new control design technique, named Power ratio gain technique, and then by L... In conjunction with general integral control, and synthesizing Singular perturbation and Equal ratio gain techniques, this paper proposes a new control design technique, named Power ratio gain technique, and then by Lyapunov method, theorem to ensure regionally as well as semi-globally asymptotic stability is established in terms of some bounded information. The highlight point is that it not only inherits all the essences of Singular perturbation and Equal ratio gain techniques but also makes up for their shortcomings, and then the conservatism of control input can be improved by compromising the Power ratio coefficients. Theoretical analysis, design example and simulation results show that Power ratio gain technique is a simple, practical and powerful tool to deal with the uncertain nonlinear system. 展开更多
关键词 generAL Integral CONTROL Nonlinear CONTROL Robust CONTROL Equal ratio GAIN TECHNIQUE SINGULAR Perturbation TECHNIQUE Power ratio GAIN TECHNIQUE Output Regulation
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GENERAL SOLUTION OF THE OVERALL BENDING OF FLEXIBLE CIRCULAR RING SHELLS WITH MODERATELY SLENDER RATIO AND APPLICATIONS TO THE BELLOWS (Ⅰ)-GOVERNING EQUATION AND GENERAL SOLUTION
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作者 ZHU Wei-ping(朱卫平) +1 位作者 HUANG Qian(黄黔) 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2002年第8期889-897,共9页
The overall bending of circular ring shells subjected to bending moments and lateral forces is discussed. The derivation of the equations was based upon the theory of flexible shells generalized by E.L. Axelrad and th... The overall bending of circular ring shells subjected to bending moments and lateral forces is discussed. The derivation of the equations was based upon the theory of flexible shells generalized by E.L. Axelrad and the assumption of the moderately slender ratio less than 1/3 (i.e., ratio between curvature radius of the meridian and distance from the meridional curvature center to the axis of revolution). The present general solution is an analytical one convergent in the whole domain of the shell and with the necessary integral constants for the boundary value problems. It can be used to calculate the stresses and displacements of the related bellows. The whole work is arranged into four parts: (Ⅰ) Governing equation and general solution; (Ⅱ) Calculation for Omega_shaped bellows; (Ⅲ) Calculation for C_shaped bellows; (Ⅳ) Calculation for U_shaped bellows. This paper is the first part. 展开更多
关键词 theory of flexible shell circular ring shell bellows lateral bending load moderately slender ratio general solution
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Nonlinear General Integral Control Design via Equal Ratio Gain Technique
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作者 Baishun Liu 《International Journal of Modern Nonlinear Theory and Application》 2014年第5期256-266,共11页
This paper proposes two kinds of nonlinear general integral controllers, that is, one is generic and another is practical, for a class of uncertain nonlinear system. By extending equal ratio gain technique to a canoni... This paper proposes two kinds of nonlinear general integral controllers, that is, one is generic and another is practical, for a class of uncertain nonlinear system. By extending equal ratio gain technique to a canonical interval system matrix and using Lyapunov method, theorems to ensure regionally as well as semi-globally asymptotic stability are established in terms of some bounded information. Moreover, for the practical nonlinear integral controller, a real time method to evaluate the equal ratio coefficient is proposed such that its value can be chosen moderately. Theoretical analysis and simulation results demonstrated that not only nonlinear general integral control can effectively deal with the uncertain nonlinear system but also equal ratio gain technique is a powerful and practical tool to solve the control design problem of dynamics with the nonlinear and uncertain actions. 展开更多
关键词 general Integral CONTROL NONLINEAR CONTROL Robust CONTROL generic Controller Equal ratio GAIN TECHNIQUE Output Regulation
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Analysis of Entropy Generation in a Rectangular Porous Duct
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作者 Shyam Lal Yadav Ashok Kumar Singh 《Journal of Applied Mathematics and Physics》 2016年第7期1336-1343,共9页
In this paper, we have considered a fully developed flow of a viscous incompressible fluid in a rectangular porous duct saturated with the same fluid. The duct is heated from the bottom for forced and mixed convection... In this paper, we have considered a fully developed flow of a viscous incompressible fluid in a rectangular porous duct saturated with the same fluid. The duct is heated from the bottom for forced and mixed convection. The Brinkman model is used to simulate the momentum transfer in the porous duct. Using the momentum and thermal energy equations, the entropy generation has been obtained due to the heat transfer, viscous and Darcy dissipations. It is found from the mathematical analysis that the entropy generation is double when the viscous as well as the Darcy dissipations terms are taken in the thermal energy equation in comparison when the viscous as well as the Darcy dissipations terms are not taken in the thermal energy equation. This result clearly shows that there is no need of taking the viscous and Darcy dissipations terms in the thermal energy equation to obtain the entropy generation. 展开更多
关键词 Brinkman Model Heat Flux Fully Developed Flow Viscosity ratio Entropy generation
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Equal Ratio Gain Technique and Its Application in Linear General Integral Control
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作者 Baishun Liu 《International Journal of Modern Nonlinear Theory and Application》 2015年第1期21-36,共16页
In conjunction with linear general integral control, this paper proposes a fire-new control design technique, named Equal ratio gain technique, and then develops two kinds of control design methods, that is, Decomposi... In conjunction with linear general integral control, this paper proposes a fire-new control design technique, named Equal ratio gain technique, and then develops two kinds of control design methods, that is, Decomposition and Synthetic methods, for a class of uncertain nonlinear system. By Routh’s stability criterion, we demonstrate that a canonical system matrix can be designed to be always Hurwitz as any row controller gains, or controller and its integrator gains increase with the same ratio. By solving Lyapunov equation, we demonstrate that as any row controller gains, or controller and its integrator gains of a canonical system matrix tend to infinity with the same ratio, if it is always Hurwitz, and then the same row solutions of Lyapunov equation all tend to zero. By Equal ratio gain technique and Lyapunov method, theorems to ensure semi-globally asymptotic stability are established in terms of some bounded information. Moreover, the striking robustness of linear general integral control and PID control is clearly illustrated by Equal ratio gain technique. Theoretical analysis, design example and simulation results showed that Equal ratio gain technique is a powerful tool to solve the control design problem of uncertain nonlinear system. 展开更多
关键词 Equal ratio GAIN TECHNIQUE general INTEGRAL CONTROL Nonlinear CONTROL Robust CONTROL OUTPUT Regulation
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Non Degeneration of Fibonacci Series, Pascal’s Elements and Hex Series
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作者 Balasubramani Prema Rangasamy 《Advances in Pure Mathematics》 2020年第7期393-404,共12页
Generally Fibonacci series and Lucas series are the same, they converge to golden ratio. After I read Fibonacci series, I thought, is there or are there any series which converges to golden ratio. Because of that I ex... Generally Fibonacci series and Lucas series are the same, they converge to golden ratio. After I read Fibonacci series, I thought, is there or are there any series which converges to golden ratio. Because of that I explored the inter relations of Fibonacci series when I was intent on Fibonacci series in my difference parallelogram. In which, I found there is no degeneration on Fibonacci series. In my thought, Pascal triangle seemed like a lower triangular matrix, so I tried to find the inverse for that. In inverse form, there is no change against original form of Pascal elements matrix. One day I played with ring magnets, which forms hexagonal shapes. Number of rings which forms Hexagonal shape gives Hex series. In this paper, I give the general formula for generating various types of Fibonacci series and its non-degeneration, how Pascal elements maintain its identities and which shapes formed by hex numbers by difference and matrices. 展开更多
关键词 Fibonacci Series Lucas Series Golden ratio Various Type of Fibonacci Series generated by Matrices Matrix Operations on Pascal’s Elements and Hex Numbers
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提高新能源场站稳定性的构网型与跟网型变流器容量配比估算
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作者 辛焕海 王宇轩 +4 位作者 刘晨曦 鞠平 马骏超 但扬清 黄林彬 《中国电机工程学报》 EI CSCD 北大核心 2024年第14期5463-5472,I0003,共11页
大规模新能源接入使得电网短路比降低,系统电压支撑强度下降,导致静态电压稳定和次/超同步振荡等稳定问题凸显。构网型变流器具有较强的电压支撑能力,在新能源场站配置一定比例的构网型变流器可以提升系统稳定性,但由于构网型变流器容... 大规模新能源接入使得电网短路比降低,系统电压支撑强度下降,导致静态电压稳定和次/超同步振荡等稳定问题凸显。构网型变流器具有较强的电压支撑能力,在新能源场站配置一定比例的构网型变流器可以提升系统稳定性,但由于构网型变流器容量与稳定裕度的解析关系不明,导致构网型变流器容量合理占比的理论值估算十分困难。该文针对新能源基地接入低短路比弱电网场景,从小干扰稳定视角探讨构网型与跟网型变流器容量配比的估算方法及其典型值。首先,对构网型变流器进行电压源等值,并通过广义短路比指标分析了构网型变流器配置比例对系统强度以及稳定裕度的影响规律;其次,针对改造构网型风电机组和额外加装构网型变流器两种技术方案,以行业相关标准为边界条件并结合典型升压变压器参数,估算了实际工程中容量配比的典型值;最后,利用多风电场系统案例验证了结论的有效性。 展开更多
关键词 构网型变流器 容量配比 广义短路比 系统强度
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基于自适应ZUPT与航向角误差修正的INS约束算法
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作者 刘宇 贺光瑞 +2 位作者 陈燕苹 邹梦强 刘小玮 《中国惯性技术学报》 EI CSCD 北大核心 2024年第4期387-393,424,共8页
为提高行人惯性导航系统(INS)的定位精度,提出了一种基于自适应零速修正算法(ZUPT)与航向角误差修正的INS约束算法。首先,利用基于广义似然比的零速检测阈值与检验统计量的特征值建立关系式,实现对零速检测阈值的自适应调整。然后,对IN... 为提高行人惯性导航系统(INS)的定位精度,提出了一种基于自适应零速修正算法(ZUPT)与航向角误差修正的INS约束算法。首先,利用基于广义似然比的零速检测阈值与检验统计量的特征值建立关系式,实现对零速检测阈值的自适应调整。然后,对INS解算位置建立线性回归模型,结合主航向与解算航向的航向差,根据行人运动类型构建观测向量和观测矩阵,对INS误差进行修正。最后,经实验验证,当行人在复杂路线变速运动时,相较于固定阈值的零速检测算法和主航向修正算法,所提算法的解算轨迹更接近真实轨迹,平均闭环误差从3.31%D减小至1.45%D,有效提高了INS定位精度,具有较好的工程应用价值。 展开更多
关键词 行人导航 零速修正 广义似然比 扩展卡尔曼滤波 航向角修正
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