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Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Vincent Froidevaux, Mélanie Decostanzi, Abdelatif Manseri, Sylvain Caillol, Bernard Boutevin, Rémi Auvergne

《化学科学与工程前沿(英文)》 2021年 第15卷 第2期   页码 330-339 doi: 10.1007/s11705-020-1929-6

摘要: This study focuses on the synthesis of new liquid aromatic bismaleimide monomers in order to improve self-curing on demand (SCOD) systems previously based on aliphatic bismaleimides. These SCOD systems are based on Diels-Alder (DA)/retro-DA reactions. The syntheses of new different aromatic bismaleimides with ester and amide bonds are presented. These maleimides have been protected using DA reaction and characterized by H NMR analysis to determine protection rate and diastereomer ratios. The retro-DA reactions of both aromatic and aliphatic DA adducts in presence of thiol molecules were studied. Kinetic analysis was monitored by H NMR and compared to model study. Finally, both aromatic and aliphatic bismaleimides-based polymers were synthesized with 2-mercaptoethyl ether and thermal properties of polymers were compared. The glass transition temperature values ranged from –20 °C to 14 °C and very good thermal stabilities were observed (up to 300 °C).

关键词: thiol-ene polymerization     self-curing on demand     thia-michael addition     Diels-Alder     maleimide    

Multiscale model of micro curing residual stress evolution in carbon fiber-reinforced thermoset polymer

Xinyu HUI, Yingjie XU, Weihong ZHANG

《机械工程前沿(英文)》 2020年 第15卷 第3期   页码 475-483 doi: 10.1007/s11465-020-0590-6

摘要: In this study, the micro curing residual stresses of carbon fiber-reinforced thermoset polymer (CFRP) composites are evaluated using a multiscale modeling method. A thermochemical coupling model is developed at the macroscale level to obtain the distributions of temperature and degree of cure. Meanwhile, a representative volume element model of the composites is established at the microscale level. By introducing the information from the macroscale perspective, the curing residual stresses are calculated using the microscale model. The evolution of curing residual stresses reveals the interaction mechanism of fiber, matrix, and interphase period during the curing process. Results show that the curing residual stresses mostly present a tensile state in the matrix and a compressive state in the fiber. Furthermore, the curing residual stresses at different locations in the composites are calculated and discussed. Simulation results provide an important guideline for the analysis and design of CFRP composite structures.

关键词: CFRP     curing residual stress     multiscale modeling     finite element method    

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

Jinian Yang, Yuxuan Xu, Chang Su, Shibin Nie, Zhenyu Li

《化学科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 1281-1295 doi: 10.1007/s11705-020-2007-9

摘要: Poor interfacial adhesion and dispersity severely obstruct the continued development of carbon nanotube (CNT)-reinforced epoxy (EP) for potential applications. Herein, hierarchical CNT nanohybrids using nickel phyllosilicate (Ni-PS) as surface decorations (CNT@Ni-PS) were synthesized, and the nanocomposites derived from varied mass fractions of EP and CNT@Ni-PS were prepared. The morphological structures, tribological performances, curing behaviors and thermal properties of EP/CNT@Ni-PS nanocomposites were carefully investigated. Results show that hierarchical CNT nanohybrids with homogeneous dispersion and well-bonded interfacial adhesion in the matrix are successfully obtained, presenting significantly improved thermal and tribological properties. Moreover, analysis on cure kinetics proves the excellent promotion of CNT@Ni-PS on the non-isothermal curing process, lowering the curing energy barrier steadily.

关键词: nickel phyllosilicate     surface decoration     tribological property     curing kinetics     thermal performance    

evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill: Effect of curingtemperature and curing time

《结构与土木工程前沿(英文)》 2023年 第17卷 第2期   页码 256-270 doi: 10.1007/s11709-022-0924-z

摘要: The curing temperature-dependent cement hydration causes the nonlinear evolution of fracture behavior and properties of fiber-reinforced cemented paste backfill (CPB) and thus influences the stability of mine backfill materials in deep mines. Therefore, the coupled effect of curing temperature (20, 35, and 45 °C) and cement hydration at different curing times (3, 7, and 28 d) on the mode-I and mode-II fracture behavior and properties of fiber-reinforced CPB is investigated. A comprehensive experimental testing program consisting of semicircular bend tests, direct shear tests, measurement of volumetric water content and matric suction, TG/DTG tests, and SEM observation is carried out. The results show that the coupled thermochemical effect results in strongly nonlinear development of pre- and post-peak behavior of fiber-reinforced CPB. Moreover, the results discover a positive linear correlation between fracture toughness and shear strength parameters and also reveal the vital role played by matric suction in the formation of fracture toughness. Furthermore, predictive functions are developed to estimate the coupled thermochemical effect on the development of KIc and KIIc. Therefore, the findings and the developed mathematical tools have the potential to promote the successful application of fiber-reinforced CPB technology in deep underground mines.

关键词: fiber reinforcement     cemented paste backfill     fracture behavior     underground mine     cement hydration    

The influence of curing conditions on the mechanical properties and leaching of inorganic polymers made

Remus I. Iacobescu, Valérie Cappuyns, Tinne Geens, Lubica Kriskova, Silviana Onisei, Peter T. Jones, Yiannis Pontikes

《化学科学与工程前沿(英文)》 2017年 第11卷 第3期   页码 317-327 doi: 10.1007/s11705-017-1622-6

摘要: This study reports on the impact of the curing conditions on the mechanical properties and leaching of inorganic polymer (IP) mortars made from a water quenched fayalitic slag. Three similar IP mortars were produced by mixing together slag, aggregate and activating solution, and cured in three different environments for 28 d: a) at 20 °C and relative humidity (RH) ~ 50% (T20RH50), b) at 20 °C and RH≥90% (T20RH90) and c) at 60 °C and RH ~ 20% (T60RH20). Compressive strength (EN 196-1) varied between 19 MPa (T20RH50) and 31 MPa (T20RH90). This was found to be attributed to the cracks formed upon curing. Geochemical modelling and two leaching tests were performed, the EA NEN 7375 tank test, and the BS EN 12457-1 single batch test. Results show that Cu, Ni, Pb, Zn and As leaching occurred even at high pH, which varied between 10 and 11 in the tank test’s leachates and between 12 and 12.5 in the single batch’s leachates. Leaching values obtained were below the requirements for non-shaped materials of Flemish legislation for As, Cu and Ni in the single batch test.

关键词: inorganic polymer     geochemical leaching modelling     heavy metals     recycling     non-ferrous fayalitic slag     curing    

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

《化学科学与工程前沿(英文)》 2022年 第16卷 第10期   页码 1530-1530 doi: 10.1007/s11705-022-2240-5

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

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    

Understanding the demand predictability of bike share systems: A station-level analysis

《工程管理前沿(英文)》   页码 551-565 doi: 10.1007/s42524-023-0279-8

摘要: Predicting demand for bike share systems (BSSs) is critical for both the management of an existing BSS and the planning for a new BSS. While researchers have mainly focused on improving prediction accuracy and analysing demand-influencing factors, there are few studies examining the inherent randomness of stations’ observed demands and to what degree the demands at individual stations are predictable. Using Divvy bike-share one-year data from Chicago, USA, we measured demand entropy and quantified the station-level predictability. Additionally, to verify that these predictability measures could represent the performance of prediction models, we implemented two commonly used demand prediction models to compare the empirical prediction accuracy with the calculated entropy and predictability. Furthermore, we explored how city- and system-specific temporally-constant features would impact entropy and predictability to inform estimating these measures when historical demand data are unavailable. Our results show that entropy of demands across stations is polarized as some stations exhibit high uncertainty (a low entropy of 0.65) and others have almost no check-out demand uncertainty (a high entropy of around 1.0). We also validated that the entropy and predictability are a priori model-free indicators for prediction error, given a sequence of bike usage demands. Lastly, we identified that key factors contributing to station-level entropy and predictability include per capita income, spatial eccentricity, and the number of parking lots near the station. Findings from this study provide more fundamental understanding of BSS demand prediction, which can help decision makers and system operators anticipate diverse station-level prediction errors from their prediction models both for existing stations and for new ones.

关键词: bike share systems     demand prediction     prediction errors     machine learning     entropy    

Optimal locations of monitoring stations in water distribution systems under multiple demand patterns: a flaw of demand coverage method and modification

Shuming LIU, Wenjun LIU, Jinduan CHEN, Qi WANG

《环境科学与工程前沿(英文)》 2012年 第6卷 第2期   页码 204-212 doi: 10.1007/s11783-011-0364-9

摘要: A flaw of demand coverage method in solving optimal monitoring stations problem under multiple demand patterns was identified in this paper. In the demand coverage method, the demand coverage of each set of monitoring stations is calculated by accumulating their demand coverage under each demand pattern, and the impact of temporal distribution between different time periods or demand patterns is ignored. This could lead to miscalculation of the optimal locations of the monitoring stations. To overcome this flaw, this paper presents a Demand Coverage Index (DCI) based method. The optimization considers extended period unsteady hydraulics due to the change of nodal demands with time. The method is cast in a genetic algorithm framework for integration with Environmental Protection Agency Net (EPANET) and is demonstrated through example applications. Results show that the set of optimal locations of monitoring stations obtained using the DCI method can represent the water quality of water distribution systems under multiple demand patterns better than the one obtained using previous methods.

关键词: demand coverage     monitoring     optimization     water distribution network     water quality    

Electricity demand, GDP and employment: evidence from Italy

Cosimo MAGAZZINO

《能源前沿(英文)》 2014年 第8卷 第1期   页码 31-40 doi: 10.1007/s11708-014-0296-8

摘要: This paper applies time series methodologies to examine the causal relationship among electricity demand, real per capita GDP and total labor force for Italy from 1970 to 2009. After a brief introduction, a survey of the economic literature on this issue is reported, before discussing the data and introducing the econometric techniques used. The results of estimation indicate that one cointegrating relationship exists among these variables. This equilibrium relation implies that, in the long-run, GDP and labor force are correlated negatively, as well as GDP and electricity. Moreover, there is a bi-directional Granger causality flow between real per capita GDP and electricity demand; while labor force does not Granger-cause neither real per capita GDP nor electricity demand. This implies that electricity demand and economic growth are jointly determined at the same time for the Italian case. The forecast error variance decomposition shows that forecast errors in real per capita GDP are mainly caused by the uncertainty in GDP itself, while forecast errors in labor force are mainly resulted from the labor force itself, although aggregate income and electricity are important, too.

关键词: energy policies     electricity demand     GDP     labor force     stationarity     structural breaks     cointegration     causality     Italy    

Scenario analysis of the energy demand and CO

Jihong ZHANG, Jian ZHOU, Guangping HU, Tianhou ZHANG

《能源前沿(英文)》 2010年 第4卷 第4期   页码 459-468 doi: 10.1007/s11708-010-0119-5

摘要: An assessment of the energy demand and the potential for sector-based emission reductions will provide necessary background information for policy makers. In this paper, Beijing was selected as a special case for analysis in order to assess the energy demand and potential of CO abatement in the urban transport system of China. A mathematical model was developed to generate three scenarios for the urban transport system of Beijing from 2010 to 2030. The best pattern was identified by comparing the three different scenarios and assessing their urban traffic patterns through cost information. Results show that in the high motorization-oriented pattern scenario, total energy demand is about 13.94% higher, and the average CO abatement per year is 3.38 million tons less than in the reference scenario. On the other hand, in the bus and rail transit-oriented scenario, total energy demand is about 11.57% less, and the average CO abatement is 2.8 million tons more than in the reference scenario. Thus, Beijing cannot and should not follow the American pattern of high motorization-oriented transport system but learn from the experience of developed cities of Europe and East Asia.

关键词: scenario analysis     urban traffic pattern     energy demand     reduction potential    

Smart residential energy management system for demand response in buildings with energy storage devices

S. L. ARUN, M. P. SELVAN

《能源前沿(英文)》 2019年 第13卷 第4期   页码 715-730 doi: 10.1007/s11708-018-0538-2

摘要: In the present scenario, the utilities are focusing on smart grid technologies to achieve reliable and profitable grid operation. Demand side management (DSM) is one of such smart grid technologies which motivate end users to actively participate in the electricity market by providing incentives. Consumers are expected to respond (demand response (DR)) in various ways to attain these benefits. Nowadays, residential consumers are interested in energy storage devices such as battery to reduce power consumption from the utility during peak intervals. In this paper, the use of a smart residential energy management system (SREMS) is demonstrated at the consumer premise to reduce the total electricity bill by optimally time scheduling the operation of household appliances. Further, the SREMS effectively utilizes the battery by scheduling the mode of operation of the battery (charging/floating/discharging) and the amount of power exchange from the battery while considering the variations in consumer demand and utility parameters such as electricity price and consumer consumption limit (CCL). The SREMS framework is implemented in Matlab and the case study results show significant yields for the end user.

关键词: smart grid     demand side management (DSM)     demand response (DR)     smart building     smart appliances     energy storage    

Modeling and simulation of industrial water demand of Beijing municipality in China

Shouke WEI, Shafi Noor ISLAM, Alin LEI,

《环境科学与工程前沿(英文)》 2010年 第4卷 第1期   页码 91-101 doi: 10.1007/s11783-010-0007-6

摘要: Statistic and econometric regression models were established in this study to analyze and predict industrial water demand, water deficits, and their future uncertainty in Beijing—a Chinese city with a severe water stress problem. A forecasting model was selected based on a modeling evaluation by comparing predictions with observations. Four scenarios were designed to simulate and analyze the future uncertainty of industrial water demand and the water deficit of Beijing. The modeling results for industrial water demand suggested that Beijing industry would face a water deficit between 3.06 × 10 min 2008 and 2.77 × 10 m in 2015, though its industrial water demand would decrease from 6.31× 10 m to 4.84 × 10 m during this period of time. Results from simulated scenario illustrated that, due to the extreme water scarcity situation, industry in Beijing would still face a serious water deficit problem even with a very optimistic scenario for the future.

关键词: water scarcity     water demand     water deficit     modeling     industry     scenario     Beijing    

Applications of thermostatically controlled loads for demand response with the proliferation of variable

Meng SONG, Wei SUN

《能源前沿(英文)》 2022年 第16卷 第1期   页码 64-73 doi: 10.1007/s11708-021-0732-5

摘要: More flexibility is desirable with the proliferation of variable renewable resources for balancing supply and demand in power systems. Thermostatically controlled loads (TCLs) attract tremendous attentions because of their specific thermal inertia capability in demand response (DR) programs. To effectively manage numerous and distributed TCLs, intermediate coordinators, e.g., aggregators, as a bridge between end users and dispatch operators are required to model and control TCLs for serving the grid. Specifically, intermediate coordinators get the access to fundamental models and response modes of TCLs, make control strategies, and distribute control signals to TCLs according the requirements of dispatch operators. On the other hand, intermediate coordinators also provide dispatch models that characterize the external characteristics of TCLs to dispatch operators for scheduling different resources. In this paper, the bottom-up key technologies of TCLs in DR programs based on the current research have been reviewed and compared, including fundamental models, response modes, control strategies, dispatch models and dispatch strategies of TCLs, as well as challenges and opportunities in future work.

关键词: thermostatically controlled load     demand response     renewable energy     power system operation    

国产环氧沥青混合料固化强度增长规律研究

钱振东,王亚奇,沈家林

《中国工程科学》 2012年 第14卷 第5期   页码 90-95

摘要:

研究了环氧沥青混合料的强度形成机理,在此基础上对影响环氧沥青混合料强度的两个重要因素即混合料的容留时间、养生温度进行了研究,确定了不同温度下环氧沥青混合料的容留时间范围及强度增长规律;采用差示扫描量热法(DSC)测得环氧沥青结合料在不同升温速率下的动态DSC曲线,通过非线性回归求得固化动力学关键参数,建立环氧沥青结合料的固化反应模型。研究结果可以指导环氧沥青混合料的生产与施工,同时对铺装层开放交通时间的确定有参考意义。

关键词: 环氧沥青     强度增长     时温条件     固化反应模型    

标题 作者 时间 类型 操作

Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Vincent Froidevaux, Mélanie Decostanzi, Abdelatif Manseri, Sylvain Caillol, Bernard Boutevin, Rémi Auvergne

期刊论文

Multiscale model of micro curing residual stress evolution in carbon fiber-reinforced thermoset polymer

Xinyu HUI, Yingjie XU, Weihong ZHANG

期刊论文

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

Jinian Yang, Yuxuan Xu, Chang Su, Shibin Nie, Zhenyu Li

期刊论文

evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill: Effect of curingtemperature and curing time

期刊论文

The influence of curing conditions on the mechanical properties and leaching of inorganic polymers made

Remus I. Iacobescu, Valérie Cappuyns, Tinne Geens, Lubica Kriskova, Silviana Onisei, Peter T. Jones, Yiannis Pontikes

期刊论文

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

期刊论文

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

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

期刊论文

Understanding the demand predictability of bike share systems: A station-level analysis

期刊论文

Optimal locations of monitoring stations in water distribution systems under multiple demand patterns: a flaw of demand coverage method and modification

Shuming LIU, Wenjun LIU, Jinduan CHEN, Qi WANG

期刊论文

Electricity demand, GDP and employment: evidence from Italy

Cosimo MAGAZZINO

期刊论文

Scenario analysis of the energy demand and CO

Jihong ZHANG, Jian ZHOU, Guangping HU, Tianhou ZHANG

期刊论文

Smart residential energy management system for demand response in buildings with energy storage devices

S. L. ARUN, M. P. SELVAN

期刊论文

Modeling and simulation of industrial water demand of Beijing municipality in China

Shouke WEI, Shafi Noor ISLAM, Alin LEI,

期刊论文

Applications of thermostatically controlled loads for demand response with the proliferation of variable

Meng SONG, Wei SUN

期刊论文

国产环氧沥青混合料固化强度增长规律研究

钱振东,王亚奇,沈家林

期刊论文