The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and p...The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and power system multidimensionally based on the operating characteristics of the cogeneration units,the hydraulic and thermodynamic characteristics of the heating network,and the energy loads.Taking a steam network supported by a gas-steam combined cycle cogeneration system as the research case,the interaction effect among the source-side prime movers,the heating networks,and the terminal demand thermal parameters were investigated based on the designed values,the plant testing data,and the validated simulation.The operating maps of the gas-steam combined cycle cogeneration units were obtained using THERMOFLEX,and the minimum source-side steam parameters of the steam network were solved using an inverse solution procedure based on the hydro-thermodynamic coupling model.The cogeneration operating maps indicate that the available operating domain considerably narrows with the rise of the extraction steam pressure and flow rate.The heating network inverse solution demonstrates that the source-side steam pressure and temperature can be optimized from the originally designed 1.11 MPa and 238.8°C to 1.074 MPa and 191.15°C,respectively.Under the operating strategy with the minimum source-side heating parameters,the power peak regulation depth remarkably increases to 18.30%whereas the comprehensive thermal efficiency decreases.The operation under the minimum source-side heating steam parameters can be superior to the originally designed one in the economy at a higher price of the heating steam.At a fuel price of$0.38/kg and the power to fuel price of 0.18 kg/(kW·h),the critical price ratio of heating steam to fuel is 119.1 kg/t.The influence of the power-fuel price ratio on the economic deviation appears relatively weak.展开更多
An inverse design of electrostatic focusing field for electrostatic and magneticimaging is investigated.Using the potential superimposition theorem of electrostatic field inmulti-electrode system,a mathematical model ...An inverse design of electrostatic focusing field for electrostatic and magneticimaging is investigated.Using the potential superimposition theorem of electrostatic field inmulti-electrode system,a mathematical model has been developed and an optimization methodhas been introduced into computation for designing the electrostatic focusing field of the imagingsystem.展开更多
Based on the available experimental and compu- tational capabilities, a phenomenological approach has been proposed to formulate a hypersurface in both spatial and temporal domains to predict combined specimen size an...Based on the available experimental and compu- tational capabilities, a phenomenological approach has been proposed to formulate a hypersurface in both spatial and temporal domains to predict combined specimen size and load- ing rate effects on the material properties [ 1-2]. A systematic investigation is being performed to understand the combined size, rate and thermal effects on the properties and deformation patterns of representative materials with different nanos- tructures and under various types of loading conditions [3- 16]. The recent study on the single crystal copper response to impact loading has revealed the size-dependence of the Hugoniot curve. In this paper, the ＂inverse Hall-Petch＂ behavior as observed in the impact response of single crystal copper, which has not been reported in the open literature, is investigated by performing molecular dynamics simulations of the response of copper nanobeam targets subjected to impacts by copper nanobeam flyers with different impact velocities. It appears from the preliminary results that the ＂inverse Hall-Petch＂ behavior in single crystal copper is mainly due to the formation and evolution of disordered atoms and the interaction between ordered and disordered atoms, as compared with the physics behind the ＂inverse Hall-Petch＂behavior as observed in nanocrystalline materials展开更多
基金Guangdong Province Key Laboratory of Efficient and Clean Energy Utilization(South China University of Technology)(2013A061401005)Research Fund(JMSWFW-2110-044)from Zhongshan Jiaming Electric Power Co.,Ltd.
文摘The determination of source-side extracted heating parameters is of great significance to the economic operation of cogeneration systems.This paper investigated the coupling performance of a cogeneration heating and power system multidimensionally based on the operating characteristics of the cogeneration units,the hydraulic and thermodynamic characteristics of the heating network,and the energy loads.Taking a steam network supported by a gas-steam combined cycle cogeneration system as the research case,the interaction effect among the source-side prime movers,the heating networks,and the terminal demand thermal parameters were investigated based on the designed values,the plant testing data,and the validated simulation.The operating maps of the gas-steam combined cycle cogeneration units were obtained using THERMOFLEX,and the minimum source-side steam parameters of the steam network were solved using an inverse solution procedure based on the hydro-thermodynamic coupling model.The cogeneration operating maps indicate that the available operating domain considerably narrows with the rise of the extraction steam pressure and flow rate.The heating network inverse solution demonstrates that the source-side steam pressure and temperature can be optimized from the originally designed 1.11 MPa and 238.8°C to 1.074 MPa and 191.15°C,respectively.Under the operating strategy with the minimum source-side heating parameters,the power peak regulation depth remarkably increases to 18.30%whereas the comprehensive thermal efficiency decreases.The operation under the minimum source-side heating steam parameters can be superior to the originally designed one in the economy at a higher price of the heating steam.At a fuel price of$0.38/kg and the power to fuel price of 0.18 kg/(kW·h),the critical price ratio of heating steam to fuel is 119.1 kg/t.The influence of the power-fuel price ratio on the economic deviation appears relatively weak.
文摘土壤重金属污染高光谱反演的特征波段提取方法和反演模型的选择是影响反演精度的关键;二者如何优化组合,提高反演精度是目前亟需解决的难题。在华南典型铬(Cr)污染区,采集了92组土壤样品,使用电感耦合等离子体质谱(inductively coupled plasma mass spectrometry,ICP-MS)检测Cr含量,并使用ASD Field Spec4地物光谱仪在实验室收集其高光谱信息。光谱信息预处理采用平滑滤波(SG)+标准正态化(SNV)+二阶微分(SD)变换组合,减弱土壤散射和噪声的影响。选择竞争性自适应重加权采样(CARS)、逐步投影算法(SPA)、无信息变量消除(UVE)、遗传算法(GA)四种算法提取特征波段。选择多元线性回归(MLR)、偏最小二乘法(PLSR)、支持向量回归(SVR)和人工神经网络(ANN)四种反演模型建立特征波段与Cr含量之间的关系。通过对比不同特征波段提取方法和反演模型组合对土壤Cr含量反演的结果发现:采用CARS和UVE特征波段提取方法可以显著提高PLSR、MLR和SVR模型的预测效果;SPA方法能够提高ANN模型的预测效果;通过SG+SNV+SD+CARS+PLSR组合方式,提取位于800~1000、1400~1700以及2100~2450 nm之间的98个特征波段,建模后模型验证,决定系数R2为0.97,均方根误差RMSE为5.25 mg·kg^(-1),平均绝对误差MAE为4.35 mg·kg^(-1),相对分析误差RPD为3.94,表明该模型在预测土壤Cr含量具有优异的性能。以土壤Cr污染高光谱反演为例,通过比较不同特征波段提取方法与反演模型组合的反演精度,确定最优模型,为小样本土壤重金属污染反演的建模提供了思路。
文摘An inverse design of electrostatic focusing field for electrostatic and magneticimaging is investigated.Using the potential superimposition theorem of electrostatic field inmulti-electrode system,a mathematical model has been developed and an optimization methodhas been introduced into computation for designing the electrostatic focusing field of the imagingsystem.
基金supported in part by the U.S.Defense Threat Reduction Agency(HDTRA1-10-1-0022)the National Key Basic Research Special Foundation of China(2010CB832704)+2 种基金the National Natural Science Foundation of China(10721062)the 111 Joint Program by the Chinese Ministry of EducationState Administration of Foreign Experts Affairs(B08014)
文摘Based on the available experimental and compu- tational capabilities, a phenomenological approach has been proposed to formulate a hypersurface in both spatial and temporal domains to predict combined specimen size and load- ing rate effects on the material properties [ 1-2]. A systematic investigation is being performed to understand the combined size, rate and thermal effects on the properties and deformation patterns of representative materials with different nanos- tructures and under various types of loading conditions [3- 16]. The recent study on the single crystal copper response to impact loading has revealed the size-dependence of the Hugoniot curve. In this paper, the ＂inverse Hall-Petch＂ behavior as observed in the impact response of single crystal copper, which has not been reported in the open literature, is investigated by performing molecular dynamics simulations of the response of copper nanobeam targets subjected to impacts by copper nanobeam flyers with different impact velocities. It appears from the preliminary results that the ＂inverse Hall-Petch＂ behavior in single crystal copper is mainly due to the formation and evolution of disordered atoms and the interaction between ordered and disordered atoms, as compared with the physics behind the ＂inverse Hall-Petch＂behavior as observed in nanocrystalline materials
