Protection and renewal of historic blocks is not only protection of physical spaces,continuation of intangible cultures,but also management measures of the internal social affairs in the blocks.Taking Chuancheng Stree...Protection and renewal of historic blocks is not only protection of physical spaces,continuation of intangible cultures,but also management measures of the internal social affairs in the blocks.Taking Chuancheng Street Historic Block in Handan City for example,this paper investigated current situation of the block,applied the organic renewal theory in the block renovation,and put forward relevant space,population and management strategies,so as to provide references for the protective renovation of historic blocks.展开更多
With the acceleration of urbanization process,there are many practical diffi culties in the renewalplanning,protection and development of some historical relics and blocks with cultural heritage in theprocess of rebui...With the acceleration of urbanization process,there are many practical diffi culties in the renewalplanning,protection and development of some historical relics and blocks with cultural heritage in theprocess of rebuilding and rejuvenating of old blocks in many cities.Laobeimen Historical Block in LepingCity,Jiangxi Province is taken as the research object,and the method of progressive protection and renewalof historical and cultural block is explored.展开更多
This review offers an overview of the latest developments in metal-covalent organic framework(MCOF)and covalent metal-organic framework(CMOF)materials,whose construction entails a combination of reversible coordinatio...This review offers an overview of the latest developments in metal-covalent organic framework(MCOF)and covalent metal-organic framework(CMOF)materials,whose construction entails a combination of reversible coordination and covalent bonding adapted from metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),respectively.With an emphasis on the MCOF and CMOF structures,this review surveys their building blocks and topologies.Specifically,the frameworks are classified based on the dimensions of their components(building blocks),namely,discrete building blocks and one-dimensional infinite building blocks.For the first category,the materials are further divided into collections of two-and three-dimensional networks based on their topologies.For the second category,the recently emerging MCOFs with woven structures are covered.Finally,the state-of-the-art in MCOF and CMOF chemistry has been laid out for promising avenues in future developments.展开更多
Better dealing with carbon issues can support the management of current greenhouse gas emissions while achieving energy economic diversification and energy security. Carbon dioxide displacement has become the most ack...Better dealing with carbon issues can support the management of current greenhouse gas emissions while achieving energy economic diversification and energy security. Carbon dioxide displacement has become the most acknowledged and practical method in enhanced oil recovery system. This is because of its oil sweep efficiency and ability to reduce the level of greenhouse gas emission. Nevertheless, it would lead to the organic solid phase deposition, which causes the changes of the wettability and the damages of wellbores and reservoirs. In this study, we used slim tube test and component test to research the dynamic characteristics of displacement process. In addition, the mechanism of porous media blockage was also investigated. Results show that when the displacement pressure closed to the minimum miscibility pressure, reservoir blockage in pore throat could happen. Component test characterizes that during near miscible displacement process, the components of oil sample varied obviously, the variation range of peak component carbon marks fluctuated strongly. Crude oil component differentiation could happen after carbon dioxide fully contacted with oil. Besides, the rapid extraction mechanism of aromatic hydrocarbons played a significant role in this process under such condition. The reason is that the solubility of saturated hydrocarbons to asphaltene and non-hydrocarbons is obviously weaker than aromatic hydrocarbons. Controlling the pressure is considered as an important link to prevent the occurrence of blocking in the carbon dioxide multiphase and multicomponent displacement process.展开更多
Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) tec...Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) technology. This paper presents a framework to evaluate blocking performance of time-slot-ted OBS networks with multi-fiber wavelength channels. The proposed model is efficient for not only single class traffic such as individual circuit switch traffics or best-effort traffics but also mixed multi-class traffics. The effectiveness of the proposed model is validated by simulation results. The study shows that blocking per-formance of multi-fiber TS-OBS network is acceptable for future Internet services.展开更多
Mobile block system is a new type of block technology based on the theory of interval block. This article focuses on the analysis of safety key points, the efficient use of emergency time, the maximum efficiency of mo...Mobile block system is a new type of block technology based on the theory of interval block. This article focuses on the analysis of safety key points, the efficient use of emergency time, the maximum efficiency of mobilizers, to reduce the loss of emergency incidents and casualties.展开更多
为解决有机化学课程教学过程中遇到的实际问题,探索因材施教的个性化培养模式,引导学生不断提升学习的主动性和解决实际问题的能力,我们基于OBE(Outcome based education)教育理念,结合中国科学技术大学有机化学课程目标和学习效果金字...为解决有机化学课程教学过程中遇到的实际问题,探索因材施教的个性化培养模式,引导学生不断提升学习的主动性和解决实际问题的能力,我们基于OBE(Outcome based education)教育理念,结合中国科学技术大学有机化学课程目标和学习效果金字塔,以学生学为中心,以成果为导向,精心设计了引导式预习、精准式授课、互助式讨论、示范式点评和全程式考核的线上线下混合“五式”教学法,在实际教学运用中取得了良好成效,达到了预期目标。展开更多
Four numerical schemes are introduced for the analysis of photocurrent transients in organic photovoltaic devices.Themathematicalmodel for organic polymer solar cells contains a nonlinear diffusion-reaction partial di...Four numerical schemes are introduced for the analysis of photocurrent transients in organic photovoltaic devices.Themathematicalmodel for organic polymer solar cells contains a nonlinear diffusion-reaction partial differential equation system with electrostatic convection attached to a kinetic ordinary differential equation.To solve the problem,Polynomial-based differential quadrature,Sinc,and Discrete singular convolution are combined with block marching techniques.These schemes are employed to reduce the problem to a nonlinear algebraic system.The iterative quadrature technique is used to solve the reduced problem.The obtained results agreed with the previous exact one and the finite element method.Further,the effects of different times,different mobilities,different densities,different geminate pair distances,different geminate recombination rate constants,different generation efficiencies,and supporting conditions on photocurrent have been analyzed.The novelty of this paper is that these schemes for photocurrent transients in organic polymer solar cells have never been presented before,so the results may be useful for improving the performance of solar cells.展开更多
The properties of top-contact organic thin-film transistors (TC-OTFTs) using ultra-thin 2, 9-dimethyl-4, 7- diphenyl-1, 10-phenanthroline (BCP) as a hole-blocking interlayer have been improved significantly and a ...The properties of top-contact organic thin-film transistors (TC-OTFTs) using ultra-thin 2, 9-dimethyl-4, 7- diphenyl-1, 10-phenanthroline (BCP) as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers arc limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at VDS = --20 V showed excellent hole mobility μFE and threshold voltage VTH of 0.58 cm^2/(V-s) and -4.6 V, respectively.展开更多
Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O<sub>3</sub> and NO. Developing new materials is important to detect and reduce air pollu...Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O<sub>3</sub> and NO. Developing new materials is important to detect and reduce air pollutants. While catalytic decomposition and zeolites are traditional ways used to reduce the amount of these gases. We need to develop and explore new promising materials. Covalent organic framework (COF) has become an attractive platform for researcher due to its extended robust covalent bonds, porosity, and crystallinity. In this study, first principal calculations were performed for gases adsorption using COFs containing nitrogen and π-bonds. Different building blocks (BBs) and linkers (LINKs/LINK1 & LINK2) were investigated by means of density functional theory (DFT) calculations with B3LYP and 3-21G basis sets to calculate the binding energies of gases @COF systems. Electrostatic potential maps (ESPM), Mulliken charges and non-covalent interaction (NCI) are used to understand the type of interactions between gas and COFs fragments. O3 was found to bind strongly with COF system in comparison with NO which could make COF a useful selective material for mixed gases environment for sensing and removal application.展开更多
文摘Protection and renewal of historic blocks is not only protection of physical spaces,continuation of intangible cultures,but also management measures of the internal social affairs in the blocks.Taking Chuancheng Street Historic Block in Handan City for example,this paper investigated current situation of the block,applied the organic renewal theory in the block renovation,and put forward relevant space,population and management strategies,so as to provide references for the protective renovation of historic blocks.
文摘With the acceleration of urbanization process,there are many practical diffi culties in the renewalplanning,protection and development of some historical relics and blocks with cultural heritage in theprocess of rebuilding and rejuvenating of old blocks in many cities.Laobeimen Historical Block in LepingCity,Jiangxi Province is taken as the research object,and the method of progressive protection and renewalof historical and cultural block is explored.
基金financially supported by the National Natural Science Foundation of China(No.22176135)the Fundamental Research Funds for the Central Universities in China(No.YJ201976)。
文摘This review offers an overview of the latest developments in metal-covalent organic framework(MCOF)and covalent metal-organic framework(CMOF)materials,whose construction entails a combination of reversible coordination and covalent bonding adapted from metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),respectively.With an emphasis on the MCOF and CMOF structures,this review surveys their building blocks and topologies.Specifically,the frameworks are classified based on the dimensions of their components(building blocks),namely,discrete building blocks and one-dimensional infinite building blocks.For the first category,the materials are further divided into collections of two-and three-dimensional networks based on their topologies.For the second category,the recently emerging MCOFs with woven structures are covered.Finally,the state-of-the-art in MCOF and CMOF chemistry has been laid out for promising avenues in future developments.
文摘Better dealing with carbon issues can support the management of current greenhouse gas emissions while achieving energy economic diversification and energy security. Carbon dioxide displacement has become the most acknowledged and practical method in enhanced oil recovery system. This is because of its oil sweep efficiency and ability to reduce the level of greenhouse gas emission. Nevertheless, it would lead to the organic solid phase deposition, which causes the changes of the wettability and the damages of wellbores and reservoirs. In this study, we used slim tube test and component test to research the dynamic characteristics of displacement process. In addition, the mechanism of porous media blockage was also investigated. Results show that when the displacement pressure closed to the minimum miscibility pressure, reservoir blockage in pore throat could happen. Component test characterizes that during near miscible displacement process, the components of oil sample varied obviously, the variation range of peak component carbon marks fluctuated strongly. Crude oil component differentiation could happen after carbon dioxide fully contacted with oil. Besides, the rapid extraction mechanism of aromatic hydrocarbons played a significant role in this process under such condition. The reason is that the solubility of saturated hydrocarbons to asphaltene and non-hydrocarbons is obviously weaker than aromatic hydrocarbons. Controlling the pressure is considered as an important link to prevent the occurrence of blocking in the carbon dioxide multiphase and multicomponent displacement process.
基金Founded by the National Natural Science Foundation of China (No.60502005).
文摘Time-slotted optical burst switched network is a potential technique to support IP over Wavelength Division Multiplexing (WDM) by introduce Time Division Multiplexing (TDM) channel to Optical Burst Switching (OBS) technology. This paper presents a framework to evaluate blocking performance of time-slot-ted OBS networks with multi-fiber wavelength channels. The proposed model is efficient for not only single class traffic such as individual circuit switch traffics or best-effort traffics but also mixed multi-class traffics. The effectiveness of the proposed model is validated by simulation results. The study shows that blocking per-formance of multi-fiber TS-OBS network is acceptable for future Internet services.
文摘Mobile block system is a new type of block technology based on the theory of interval block. This article focuses on the analysis of safety key points, the efficient use of emergency time, the maximum efficiency of mobilizers, to reduce the loss of emergency incidents and casualties.
文摘为解决有机化学课程教学过程中遇到的实际问题,探索因材施教的个性化培养模式,引导学生不断提升学习的主动性和解决实际问题的能力,我们基于OBE(Outcome based education)教育理念,结合中国科学技术大学有机化学课程目标和学习效果金字塔,以学生学为中心,以成果为导向,精心设计了引导式预习、精准式授课、互助式讨论、示范式点评和全程式考核的线上线下混合“五式”教学法,在实际教学运用中取得了良好成效,达到了预期目标。
文摘Four numerical schemes are introduced for the analysis of photocurrent transients in organic photovoltaic devices.Themathematicalmodel for organic polymer solar cells contains a nonlinear diffusion-reaction partial differential equation system with electrostatic convection attached to a kinetic ordinary differential equation.To solve the problem,Polynomial-based differential quadrature,Sinc,and Discrete singular convolution are combined with block marching techniques.These schemes are employed to reduce the problem to a nonlinear algebraic system.The iterative quadrature technique is used to solve the reduced problem.The obtained results agreed with the previous exact one and the finite element method.Further,the effects of different times,different mobilities,different densities,different geminate pair distances,different geminate recombination rate constants,different generation efficiencies,and supporting conditions on photocurrent have been analyzed.The novelty of this paper is that these schemes for photocurrent transients in organic polymer solar cells have never been presented before,so the results may be useful for improving the performance of solar cells.
基金supported by the National High Technology Research and Development Program of China (Grant No 2006AA03Z0412)the National Natural Science Foundation of China (Grant Nos 10774013 and 10804006)+4 种基金the Excellent Doctor’s Science and Technology Innovation Foundation of Beijing Jiaotong University (Grant No 48024)the Foundation of Beijing Jiaotong University (Grant No 2005SM057)the Research Fund for the Youth Scholars of the Doctoral Program of Higher Education (Grant No 20070004031)the Beijing NOVA program (Grant No 2007A024)Sponsored by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry
文摘The properties of top-contact organic thin-film transistors (TC-OTFTs) using ultra-thin 2, 9-dimethyl-4, 7- diphenyl-1, 10-phenanthroline (BCP) as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers arc limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at VDS = --20 V showed excellent hole mobility μFE and threshold voltage VTH of 0.58 cm^2/(V-s) and -4.6 V, respectively.
文摘Industrial growth in recent years led to air pollution and an increase in concentration of hazardous gases such as O<sub>3</sub> and NO. Developing new materials is important to detect and reduce air pollutants. While catalytic decomposition and zeolites are traditional ways used to reduce the amount of these gases. We need to develop and explore new promising materials. Covalent organic framework (COF) has become an attractive platform for researcher due to its extended robust covalent bonds, porosity, and crystallinity. In this study, first principal calculations were performed for gases adsorption using COFs containing nitrogen and π-bonds. Different building blocks (BBs) and linkers (LINKs/LINK1 & LINK2) were investigated by means of density functional theory (DFT) calculations with B3LYP and 3-21G basis sets to calculate the binding energies of gases @COF systems. Electrostatic potential maps (ESPM), Mulliken charges and non-covalent interaction (NCI) are used to understand the type of interactions between gas and COFs fragments. O3 was found to bind strongly with COF system in comparison with NO which could make COF a useful selective material for mixed gases environment for sensing and removal application.