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Automated synthesis of steady-state continuous processes using reinforcement learning

《化学科学与工程前沿（英文）》 2022年 第16卷 第2期   页码 288-302 doi: 10.1007/s11705-021-2055-9

摘要： Automated flowsheet synthesis is an important field in computer-aided process engineering. The present work demonstrates how reinforcement learning can be used for automated flowsheet synthesis without any heuristics or prior knowledge of conceptual design. The environment consists of a steady-state flowsheet simulator that contains all physical knowledge. An agent is trained to take discrete actions and sequentially build up flowsheets that solve a given process problem. A novel method named SynGameZero is developed to ensure good exploration schemes in the complex problem. Therein, flowsheet synthesis is modelled as a game of two competing players. The agent plays this game against itself during training and consists of an artificial neural network and a tree search for forward planning. The method is applied successfully to a reaction-distillation process in a quaternary system.

关键词： automated process synthesis     flowsheet synthesis     artificial intelligence     machine learning     reinforcement learning    

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Modeling and analysis of steady-state vibration induced by backlash in servo rotary table

Xiao YANG,Dun LU,Sanli LIU,Jun ZHANG,Wanhua ZHAO

《机械工程前沿（英文）》 2015年 第10卷 第1期   页码 43-47 doi: 10.1007/s11465-015-0327-0

摘要：

Backlash cannot be always avoided in mechanical systems because of wear or looseness. Steady-state vibration may be induced by backlash in closed loop feed drive systems. This paper presents a mathematical model of a servo rotary table, considering the effect of backlash. The accuracy of this model is verified by an experiment. The influences of the parameters, such as position controller gain, velocity controller gain, load and the magnitude of backlash, on steady-state vibration are discussed. The steady-state vibration amplitude increases with the position controller gain, load and the magnitude of backlash. The steady-state vibration frequency increases with the position controller gain and the velocity controller gain, while an increase in load leads to a decrease in the frequency.

关键词： backlash     servo rotary table     steady-state vibration    

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Effect of dilution rate on dynamic and steady-state biofilm characteristics during phenol biodegradation

Veena Bangalore Rangappa, Vidya Shetty Kodialbail, Saidutta Malur Bharthaiyengar

《环境科学与工程前沿（英文）》 2016年 第10卷 第4期 doi: 10.1007/s11783-016-0863-9

摘要： Continuous pulsed plate bioreactor (PPBR) was used for phenol biodegradation. cells immobilized on granular activated carbon was used. Dynamic and steady state biofilm characteristics depend on dilution rate (DR). Lower DR favour phenol degradation and uniform, thick biofilm formation. Exo polymeric substance production in biofilm are favoured at lower dilution rates. Pulsed plate bioreactor (PPBR) is a biofilm reactor which has been proven to be very efficient in phenol biodegradation. The present paper reports the studies on the effect of dilution rate on the physical, chemical and morphological characteristics of biofilms formed by the cells of Pseudomonas desmolyticum on granular activated carbon (GAC) in PPBR during biodegradation of phenol. The percentage degradation of phenol decreased from 99% to 73% with an increase in dilution rate from 0.33 h?1 to 0.99 h?1 showing that residence time in the reactor governs the phenol removal efficiency rather than the external mass transfer limitations. Lower dilution rates favor higher production of biomass, extracellular polymeric substances (EPS) as well as the protein, carbohydrate and humic substances content of EPS. Increase in dilution rate leads to decrease in biofilm thickness, biofilm dry density, and attached dry biomass, transforming the biofilm from dense, smooth compact structure to a rough and patchy structure. Thus, the performance of PPBR in terms of dynamic and steady-state biofilm characteristics associated with phenol biodegradation is a strong function of dilution rate. Operation of PPBR at lower dilution rates is recommended for continuous biologic treatment of wastewaters for phenol removal.

关键词： Biofilm     Exopolymeric substances     Phenol     Dilution rate     Pulsed plate bioreactor    

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Steady-state thermal-hydraulic analysis of SCWR assembly

LIU Xiaojing, CHENG Xu

《能源前沿（英文）》 2008年 第2卷 第4期   页码 475-478 doi: 10.1007/s11708-008-0093-3

摘要： Among the six gen-IV reactor concepts recommended by the gen-IV international forum (GIF), supercritical water-cooled reactor (SCWR), the only reactor with water as coolant, achieves a high thermal efficiency and, subsequently, has economic advantages over the existing reactors due to its high outlet temperature. A thermal-hydraulic analysis of the SCWR assembly is performed in this paper using the modified COBRA-IV code. Two approaches to reduce the hot channel factor are investigated: decreasing the moderator mass flow and increasing the thermal resistance between moderator channel and its adjacent sub-channels. It is shown that heat transfer deterioration cannot be avoided in SCWR fuel assembly. It is, therefore, highly required to calculate the cladding temperature accurately and to preserve the fuel rod cladding integrity under heat transfer deterioration conditions.

关键词： cladding temperature     assembly     temperature     coolant     resistance    

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高压VDMOS的一种高精度静态物理模型

鲍嘉明,孙伟锋,赵 野,陆生礼

《中国工程科学》 2008年 第10卷 第2期   页码 72-78

摘要：

提出了高压VDMOS的一种高精度静态物理模型(HASPM)。在该模型中，基于更为合理的假设而使得用解析方法求得了双扩散沟道区中的电场和电压；通过深入研究VDMOS 内部的物理特性，给出了一个关于漂移区电场的微分方程，并在整个漂移区都用解析方法求解了该微分方程，由此求得了漂移区的电压降。计算结果表明， 该模型在漏端电流接近饱和处的稳定性有较大提高，具有较高的计算精度，特别是在栅电压与漏电压都比较大的情况下，其计算精度有较大程度的提高。

关键词： 垂直双扩散MOS场效应晶体管     静态物理模型     解析方法    

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Influence of initial curing conditions and exposure environments on chloride migration in concrete using electrochemical method

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 348-353 doi: 10.1007/s11709-010-0077-3

摘要： To investigate the influence of initial curing conditions and exposure environments on chloride ions’ migration in concrete, the specimens that were cured in different conditions and placed in several marine environments were studied. The amount of chloride ions passing through the specimen’s section was monitored in the accelerated chloride migration test. The effective chloride diffusion coefficients () were calculated from the steady-state on the basis of Nernst-Planck’s equation. The results indicated that the initial curing conditions and the wet-dry interval of external environments have coupling influence on effective diffusion coefficient of chloride ion significantly. reflected the density and pore connectivity of concrete. The co-effects of the initial curing condition and following exposure environment should be taken into account in durability design for concrete structure located in marine environment.

关键词： durability     effective diffusion coefficient     steady-state     migration test    

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An improved delta-star switching scheme for reactive power saving in three-phase induction motors

P. RAJA,N. KUMARESAN,M. SUBBIAH

《能源前沿（英文）》 2014年 第8卷 第3期   页码 364-370 doi: 10.1007/s11708-014-0324-8

摘要： It is proposed that a capacitor can be connected permanently across each phase winding of a three-phase induction motor along with the conventional delta-star switching, for further saving in VARh at reduced loads on the motor. The method of choosing a suitable value for the capacitor and the criteria to be adopted for calculating the power output at which the star to delta switching is to be made are also explained. The experimental results on a 3-phase, 4-pole, 415 V, 50 Hz, 3.3 kW induction motor verify the advantages in adding the capacitor to the phase winding of the motor. Compared to using only a single delta connected stator winding or a delta-star switching, the advantages of the proposed addition of a capacitor, are also demonstrated through a case study conducted on a 400 V, 250 kW motor. Any further improvement in grid side power factor can be achieved by employing a static synchronous compensator (STATCOM) of reduced VAR rating.

关键词： delta-star switching     induction motor     power factor     steady-state analysis    

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A numerical study of helium-heated inorganic membrane reformer coupling to HTGR

YIN Huaqiang, JIANG Shengyao, JU Huaiming, ZHANG Youjie

《能源前沿（英文）》 2007年 第1卷 第4期   页码 446-450 doi: 10.1007/s11708-007-0065-3

摘要： Based on one-dimensional quasi-homogeneous model, a steady-state model and its computer program were developed for helium-heated inorganic membrane reformer coupling to high temperature gas-cooled reactor (HTGR). The results show

关键词： temperature gas-cooled     one-dimensional quasi-homogeneous     steady-state     helium-heated    

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Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

《结构与土木工程前沿（英文）》 2008年 第2卷 第1期   页码 56-66 doi: 10.1007/s11709-008-0001-2

摘要： Present paper deals with the computing of passive earth pressure acting on the vertical rigid retaining wall supporting the soil mass subjected to water seepage. The basic assumptions of Coulomb’s theory and the 2-dimensional steady flow function are used. Three Coulomb-type solutions for the passive earth pressures are presented for the walls provided with three different drainage systems respectively. Based on the general solutions, the variations of the critical inclination of the failure surface and the coefficient of passive earth pressure with increasing the effective friction angle of the soil mass, the soil/structure friction angle, and the water/soil unit weight ratio are discussed. Two tables with values of the coefficients of passive earth pressure for Cases 1 and 3 respectively are also presented.

关键词： function     coefficient     Coulomb-type     effective friction     different drainage    

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Effect of steady shear on multi-axial texture of symmetric diblock copolymers

XU Hui, LIU Honglai, HU Ying

《化学科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 26-34 doi: 10.1007/s11705-007-0006-8

摘要： The effect of steady shear on multi-axial texture of symmetric diblock copolymer was investigated by using dynamic density functional theory. Through modifying the periodic boundary condition, the parallel-transverse biaxial texture and perpendicular-parallel-transverse triaxial texture have been observed. In the formation of the multi-axial texture, there are two critical velocities μ and µ, at which the transition between the perpendicular and the parallel lamellar morphology, and the transition between the parallel and the transverse lamellar morphology occur, respectively. The two critical velocities increase as the interaction parameter increases, but they almost remain constant at different shear rates. Furthermore, the rotation from the transverse lamellae to the parallel lamellae induced by the shear strain, and the increase of lamellar spacings of the three lamellae after removing the shear, have also been observed by the time evolution of the morphologies. These phenomena are consistent with experimental work.
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Analysis and control of wind-driven self-excited induction generators connected to the grid through power converters

S. Senthil KUMAR, N. KUMARESAN, N. Ammasai GOUNDEN, Namani RAKESH

《能源前沿（英文）》 2012年 第6卷 第4期   页码 403-412 doi: 10.1007/s11708-012-0208-8

摘要： The analysis of the wind-driven self-excited induction generators (SEIGs) connected to the grid through power converters has been developed in this paper. For this analysis, a method of representing the grid power as equivalent load resistance in the steady-state equivalent circuit of SEIG has been formulated. The technique of genetic algorithm (GA) has been adopted for making the analysis of the proposed system simple and straightforward. The control of SEIG is attempted by connecting an uncontrolled diode bridge rectifier (DBR) and a line commutated inverter (LCI) between the generator terminals and three-phase utility grid. A simple control technique for maximum power point tracking (MPPT) in wind energy conversion systems (WECS), in which the firing angle of the LCI alone needs to be controlled by sensing the rotor speed of the generator has been proposed. The effectiveness of the proposed method of MPPT and method of analysis of this wind-driven SEIG-converter system connected to the grid through power converters has been demonstrated by experiments and simulation. These experimental and simulated results confirm the usefulness and successful working of the proposed system and its analysis.

关键词： self-excited induction generator (SEIG)     renewable power generation     power converters     maximum power point tracking (MPPT)     steady state analysis     power generation systems    

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Development of a steady thermal-hydraulic analysis code for the China Advanced Research Reactor

TIAN Wenxi, QIU Suizheng, GUO Yun, SU Guanghui, JIA Dounan, LIU Tiancai, ZHANG Jianwei

《能源前沿（英文）》 2007年 第1卷 第2期   页码 189-194 doi: 10.1007/s00000-007-0024-8

摘要： A multi-channel model steady-state thermal-hydraulic analysis code was developed for the China Advanced Research Reactor (CARR). By simulating the whole reactor core, the detailed mass flow distribution in the core was obtained. The result shows that structure size plays the most important role in mass flow distribution, and the influence of core power could be neglected under single-phase flow. The temperature field of the fuel element under unsymmetrical cooling condition was also obtained, which is necessary for further study such as stress analysis, etc. of the fuel element. At the same time, considering the hot channel effect including engineering factor and nuclear factor, calculation of the mean and hot channel was carried out and it is proved that all thermal-hydraulic parameters satisfy the Safety design regulation of CARR .

关键词： detailed     calculation     unsymmetrical     temperature     channel    

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城市给水管网恒定流和瞬变流数学模型研究

汪守东,沈永明,姜恒志

《中国工程科学》 2007年 第9卷 第12期   页码 26-30

摘要：

首先基于节点方程法，建立了给水管网恒定流数学模型，并采用经改进的牛顿迭代法实现了对模型的求解；其次由特征线法建立了给水管网瞬变流数学模型，可预测管网运行中出现的有害水击，并求得可能出现的最大(最小)水压及其相应发生的位置。实例研究表明，建立的模型是可靠的，且具有计算速度快、精度高等优点，可以用于城市给水管网的水力平衡数值模拟研究和为设计者防护水击所采取的措施提供理论依据。

关键词： 给水管网     恒定流     瞬变流     水击     牛顿迭代法    

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Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 605-617 doi: 10.1007/s11709-018-0499-x

摘要： Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed, where the mean wind and aeroelastic loads are applied simultaneously in time domain. A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads, which leads to incorrect mean wind structural responses. It is found that the mathematic expectations (or limiting characteristics) of the aeroelastic models are fundamental to this kind of incompatibility. In this paper, two aeroelastic models are presented and discussed, one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted). It is shown that, in cases of low wind speeds, the IF-denoted model reflects correctly the mean wind load properties, and results in correct mean structural responses; in contrast, the RF-denoted model leads to incorrect mean responses due to its nonphysical mean properties. At very high wind speeds, however, even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic nonlinearity. To solve the incompatibility at high wind speeds, a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this work. Finally, with the method presented, aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge     aerodynamics     nonlinear     aeroelastic model     Pseudo-steady     mean wind loads    

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渠网恒定流及非恒定流数学模型的研究及应用

张明亮,沈永明

《中国工程科学》 2007年 第9卷 第8期   页码 92-96

摘要：

从求解一维圣维南方程组的Preissmann 4点隐式差分格式出发, 建立了一维河网及渠网数学模型，并对计算中所涉及的一些关键技术问题进行了较为详细的阐述。利用模型对树状渠网的恒定流及复杂的环状渠网和河网的非恒定流对模型进行验证。验证结果表明，水位和流量过程计算值与Islam的计算值吻合较好，各渠道的流量分配计算结果精度也较高，为河网及渠网的水量调度提供了一个较为简便实用的工具，为建立渠网及河网的综合水质生态数学模型打下基础。

关键词： Preissmann格式     渠网及河网     流量分配     水质模型    

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标题 作者 时间 类型 操作

Automated synthesis of steady-state continuous processes using reinforcement learning

期刊论文

Modeling and analysis of steady-state vibration induced by backlash in servo rotary table

Xiao YANG,Dun LU,Sanli LIU,Jun ZHANG,Wanhua ZHAO

期刊论文

Effect of dilution rate on dynamic and steady-state biofilm characteristics during phenol biodegradation

Veena Bangalore Rangappa, Vidya Shetty Kodialbail, Saidutta Malur Bharthaiyengar

期刊论文

Steady-state thermal-hydraulic analysis of SCWR assembly

LIU Xiaojing, CHENG Xu

期刊论文

高压VDMOS的一种高精度静态物理模型

鲍嘉明,孙伟锋,赵 野,陆生礼

期刊论文

Influence of initial curing conditions and exposure environments on chloride migration in concrete using electrochemical method

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

期刊论文

An improved delta-star switching scheme for reactive power saving in three-phase induction motors

P. RAJA,N. KUMARESAN,M. SUBBIAH

期刊论文

A numerical study of helium-heated inorganic membrane reformer coupling to HTGR

YIN Huaqiang, JIANG Shengyao, JU Huaiming, ZHANG Youjie

期刊论文

Coulomb-type solutions for passive earth pressure with steady seepage

WANG Junjie, CHAI Hejun, LIN Xin, XU Jiamei

期刊论文

Effect of steady shear on multi-axial texture of symmetric diblock copolymers

XU Hui, LIU Honglai, HU Ying

期刊论文

Analysis and control of wind-driven self-excited induction generators connected to the grid through power converters

S. Senthil KUMAR, N. KUMARESAN, N. Ammasai GOUNDEN, Namani RAKESH

期刊论文

Development of a steady thermal-hydraulic analysis code for the China Advanced Research Reactor

TIAN Wenxi, QIU Suizheng, GUO Yun, SU Guanghui, JIA Dounan, LIU Tiancai, ZHANG Jianwei

期刊论文

城市给水管网恒定流和瞬变流数学模型研究

汪守东,沈永明,姜恒志

期刊论文

Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

期刊论文

渠网恒定流及非恒定流数学模型的研究及应用

张明亮,沈永明

期刊论文