为了进一步降低园区综合能源系统(park-level integrated energy system,PIES)碳排放量,优化热电联产(combined heat and power,CHP)机组出力的灵活性,提出一种考虑改进阶梯型碳交易和CHP热电灵活输出的PIES低碳经济调度策略。首先,将...为了进一步降低园区综合能源系统(park-level integrated energy system,PIES)碳排放量,优化热电联产(combined heat and power,CHP)机组出力的灵活性,提出一种考虑改进阶梯型碳交易和CHP热电灵活输出的PIES低碳经济调度策略。首先,将遗传算法与模糊控制相结合,设计一种遗传模糊碳交易参数优化器,从而对现有阶梯型碳交易机制进行改进,实现该机制参数的自适应变化;其次,在传统CHP中加入卡琳娜(Kalina)循环与电锅炉(electricboiler,EB),构造CHP热电灵活输出模型,以同时满足电、热负荷的不同需求;然后,提出一种柔性指标——电、热输出占比率,进而计算出电、热输出占比率区间,以衡量CHP运行灵活性;最后,将改进阶梯型碳交易机制和CHP热电灵活输出模型协同优化,以系统运行成本和碳交易成本之和最小为目标,构建PIES低碳经济优化模型。算例分析表明,所提策略可有效降低经济成本和碳排放量,同时还可扩展CHP灵活输出调节范围,能够为PIES低碳经济调度提供参考。展开更多
精准度量复杂网络中节点的重要程度有助于研究网络的抗毁性和鲁棒性。为弥补现有算法评估角度片面的局限性,该文将范德华力引入复杂网络中,将网络中的节点映射为分子或原子,并将节点的度值表示为分子或原子的范德华常量,用范德华力来定...精准度量复杂网络中节点的重要程度有助于研究网络的抗毁性和鲁棒性。为弥补现有算法评估角度片面的局限性,该文将范德华力引入复杂网络中,将网络中的节点映射为分子或原子,并将节点的度值表示为分子或原子的范德华常量,用范德华力来定义节点的影响力,综合考虑节点间路径信息的占比率,提出一种基于范德华力的重要节点挖掘算法VDWF(Van der Waals Force)。该算法兼顾网络的局部信息以及全局拓扑结构等特征。为验证该算法的有效性与适用性,分别采用单调性指标、网络效率以及极大连通系数等作为评估指标,并选取6个不同领域的真实数据集与其它算法进行对照实验。结果表明,范德华力算法能够更加有效地挖掘复杂网络中的重要节点,精准区分不同节点的重要性差异。展开更多
Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle ...Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.展开更多
Based on orthogonal experiments,the effects of voltage,frequency,duty ratio and their interactions on the thickness and corrosion resistance of coatings prepared by plasma electrolytic oxidation(PEO)on aluminum in an ...Based on orthogonal experiments,the effects of voltage,frequency,duty ratio and their interactions on the thickness and corrosion resistance of coatings prepared by plasma electrolytic oxidation(PEO)on aluminum in an alkaline silicate-containing electrolyte were investigated.The thicknesses of these coatings were obtained by measuring their cross-section using Image J software.Their corrosion resistances were evaluated in HCl and NaCl media through spot test and electrochemical test.The results show that the experimental design of this study is the key to investigate the interactions among these electrical parameters.Additionally,not only each independent factor,but also their interactions exhibit a remarkable influence on the coatings.The combination of high voltage,low frequency and large duty ratio significantly increases the coating thickness and content of the corrosion resistance phase,and thus improves the corrosion resistance of the coating in HNO3 medium.Conversely,the coating possessing the densest microstructure and best corrosion resistance in NaCl medium is obtained when low voltage and high frequency match with a small duty ratio.展开更多
Effects of current density, duty cycle and frequency on microstructure and particles content of electrodeposited Co-BN （hexagonal） nano composite coatings were analyzed by SEM, FESEM, EDS, AFM and XRD techniques. Th...Effects of current density, duty cycle and frequency on microstructure and particles content of electrodeposited Co-BN （hexagonal） nano composite coatings were analyzed by SEM, FESEM, EDS, AFM and XRD techniques. The microhardness, tribological behavior and wear mechanism were also investigated. Generally, as the current density and frequency increased, the particles content and microhardness of the coatings increased firstly and then decreased. Moreover, by reducing duty cycle, more particles were incorporated and higher microhardness was obtained. The best tribological behavior was achieved under the conditions duty cycle of 10%, frequency of 50 Hz and current density of 100 mA/cm2.展开更多
In low-duty-cycle wireless sensor networks,designers have to cope with unreliable links and limited communication capacity.In this work,we propose COST,a coding scheme that leverages spatial-temporal diversity to achi...In low-duty-cycle wireless sensor networks,designers have to cope with unreliable links and limited communication capacity.In this work,we propose COST,a coding scheme that leverages spatial-temporal diversity to achieve higher energy efficiency and lower delay of packet transmissions.We particularly address long sleeping intervals in low-duty-cycle networks by exploiting multi-path diversity.Specifically,we propose to employ an erasure-coding scheme to improve reliability.With respect to energy efficiency and delivery timeliness,we formulate the problem in optimal allocation of coded blocks over multiple paths,which is then proved to be NP-hard.We further propose a near-optimal algorithm to solve the allocation problem.Through extensive simulations,we evaluate the impact of network parameters and demonstrate the effectiveness of our proposal.展开更多
文摘为了进一步降低园区综合能源系统(park-level integrated energy system,PIES)碳排放量,优化热电联产(combined heat and power,CHP)机组出力的灵活性,提出一种考虑改进阶梯型碳交易和CHP热电灵活输出的PIES低碳经济调度策略。首先,将遗传算法与模糊控制相结合,设计一种遗传模糊碳交易参数优化器,从而对现有阶梯型碳交易机制进行改进,实现该机制参数的自适应变化;其次,在传统CHP中加入卡琳娜(Kalina)循环与电锅炉(electricboiler,EB),构造CHP热电灵活输出模型,以同时满足电、热负荷的不同需求;然后,提出一种柔性指标——电、热输出占比率,进而计算出电、热输出占比率区间,以衡量CHP运行灵活性;最后,将改进阶梯型碳交易机制和CHP热电灵活输出模型协同优化,以系统运行成本和碳交易成本之和最小为目标,构建PIES低碳经济优化模型。算例分析表明,所提策略可有效降低经济成本和碳排放量,同时还可扩展CHP灵活输出调节范围,能够为PIES低碳经济调度提供参考。
文摘精准度量复杂网络中节点的重要程度有助于研究网络的抗毁性和鲁棒性。为弥补现有算法评估角度片面的局限性,该文将范德华力引入复杂网络中,将网络中的节点映射为分子或原子,并将节点的度值表示为分子或原子的范德华常量,用范德华力来定义节点的影响力,综合考虑节点间路径信息的占比率,提出一种基于范德华力的重要节点挖掘算法VDWF(Van der Waals Force)。该算法兼顾网络的局部信息以及全局拓扑结构等特征。为验证该算法的有效性与适用性,分别采用单调性指标、网络效率以及极大连通系数等作为评估指标,并选取6个不同领域的真实数据集与其它算法进行对照实验。结果表明,范德华力算法能够更加有效地挖掘复杂网络中的重要节点,精准区分不同节点的重要性差异。
基金Project (50801056) supported by the National Natural Science Foundation of ChinaProject (2005DKA10400-Z20) supported by the National R&D Infrastructure and Facility Development Program of ChinaProject supported by the Zijin Project of Zhejiang University, China
文摘Micro-arc oxidation （MAO） process was carried out on AZ91D alloy in alkaline borate solution using an alternative square-wave power source with different parameters. The effects of voltage, frequency and duty cycle on the coatings were investigated by orthogonal experiment. It is found that the thickness of coatings increases with the increase of voltage and duty cycle, but decreases with the increase of frequency. The structure and morphology of the coatings also depend on voltage, frequency and duty cycle. The coatings become more porous and crack with increasing voltage and duty cycle. The coating is thin and transparent when the voltage is lower than 120 V. The corrosion resistances of different coatings were evaluated by polarization curves and electrochemical impedance spectroscopy （EIS） in 3.5% NaCl （mass fraction） solution. When the optimized values of voltage, frequency and duty cycle are 140 V, 2 000 Hz and 0.4, respectively, the anodic coating shows the best corrosion resistance.
基金Project(1111RJDA011)supported by the Creative Research Group Fund of Gansu Province,ChinaProject(SKLAB02015006)supported by the State Key Laboratory Open Fund of Advanced Processing and Recycling of Nonferrous Metals,China。
文摘Based on orthogonal experiments,the effects of voltage,frequency,duty ratio and their interactions on the thickness and corrosion resistance of coatings prepared by plasma electrolytic oxidation(PEO)on aluminum in an alkaline silicate-containing electrolyte were investigated.The thicknesses of these coatings were obtained by measuring their cross-section using Image J software.Their corrosion resistances were evaluated in HCl and NaCl media through spot test and electrochemical test.The results show that the experimental design of this study is the key to investigate the interactions among these electrical parameters.Additionally,not only each independent factor,but also their interactions exhibit a remarkable influence on the coatings.The combination of high voltage,low frequency and large duty ratio significantly increases the coating thickness and content of the corrosion resistance phase,and thus improves the corrosion resistance of the coating in HNO3 medium.Conversely,the coating possessing the densest microstructure and best corrosion resistance in NaCl medium is obtained when low voltage and high frequency match with a small duty ratio.
文摘Effects of current density, duty cycle and frequency on microstructure and particles content of electrodeposited Co-BN （hexagonal） nano composite coatings were analyzed by SEM, FESEM, EDS, AFM and XRD techniques. The microhardness, tribological behavior and wear mechanism were also investigated. Generally, as the current density and frequency increased, the particles content and microhardness of the coatings increased firstly and then decreased. Moreover, by reducing duty cycle, more particles were incorporated and higher microhardness was obtained. The best tribological behavior was achieved under the conditions duty cycle of 10%, frequency of 50 Hz and current density of 100 mA/cm2.
基金This work was supported in part by the National Basic Research Program of China(Grant No.2011CB302705)the National Natural Science Foundation of China(GrantNos.61003277,60903206)+1 种基金the State key DevelopmentProgram for Basic Research of China(No.2009CB3020402)the National Natural Science Foun-dation of Jiangsu Province(Grant No.BK2010102)
文摘In low-duty-cycle wireless sensor networks,designers have to cope with unreliable links and limited communication capacity.In this work,we propose COST,a coding scheme that leverages spatial-temporal diversity to achieve higher energy efficiency and lower delay of packet transmissions.We particularly address long sleeping intervals in low-duty-cycle networks by exploiting multi-path diversity.Specifically,we propose to employ an erasure-coding scheme to improve reliability.With respect to energy efficiency and delivery timeliness,we formulate the problem in optimal allocation of coded blocks over multiple paths,which is then proved to be NP-hard.We further propose a near-optimal algorithm to solve the allocation problem.Through extensive simulations,we evaluate the impact of network parameters and demonstrate the effectiveness of our proposal.
