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Molecular dynamics study of water diffusion in an amphiphilic block copolymer with large difference in the blocks’ glass transition temperatures

Yang Zhou, Phillip Choi

《化学科学与工程前沿（英文）》 2017年 第11卷 第3期   页码 440-447 doi: 10.1007/s11705-017-1626-2

摘要： Isothermal-isobaric molecular dynamics simulation was used to study the diffusion mechanism of water in polyurethane- -poly( -isopropyl acrylamide) (PU- -PNIPAm) with a hydrophobic PU/hydrophilic PNIPAm mass ratio of 1.4 to 1 at 298 K and 450 K. Here, the experimental glass transition temperature ( ) of PU is 243 K while that of PNIPAm is 383 K. Different amounts of water up to 15 wt-% were added to PU- -PNIPAm. We were able to reproduce the specific volumes and glass transition temperatures (250 K and 390 K) of PU- -PNIPAm. The computed self-diffusion coefficient of water increased exponentially with increasing water concentration at both temperatures (i.e., following the free volume model of Fujita). It suggested that water diffusion in PU- -PNIPAm depends only on its fractional free volume despite the free volume inhomogeneity. It is noted that at 298 K, PU is rubbery while PNIPAm is glassy. Regardless of temperature, radial distribution functions showed that water formed clusters with sizes in the range of 0.2–0.4 nm in PU- -PNIPAm. At low water concentrations, more clusters were found in the PU domain but at high water concentrations, more in the PNIPAm domain. It is believed that water molecules diffuse as clusters rather than as individual molecules.

关键词： molecular dynamics simulation     amphiphilic block copolymer     free volume     water diffusivity     fujita model    

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Responding to the Paris Climate Agreement: global climate change mitigation efforts

Yong GENG, Tsuyoshi FUJITA, Anthony CHIU, Hancheng DAI, Han HAO

《能源前沿（英文）》 2018年 第12卷 第3期   页码 333-337 doi: 10.1007/s11708-018-0587-6

摘要：

关键词： valign=     top     class=     J_zhaiyao    

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Proliferation of district heating using local energy resources through strategic building-stock management: A case study in Fukushima, Japan

Yi DOU, Keijiro OKUOKA, Minoru FUJII, Hiroki TANIKAWA, Tsuyoshi FUJITA, Takuya TOGAWA, Liang DONG

《能源前沿（英文）》 2018年 第12卷 第3期   页码 411-425 doi: 10.1007/s11708-018-0577-8

摘要：

District heating systems using cogeneration technology and renewable resources are considered as an effective approach to resources conservation and reduction of greenhouse gas (GHG) emissions. However, wide-spread aging and depopulation problems, as well as the popularization of energy-saving technologies in buildings, are estimated to greatly decrease energy consumption, leading to inefficiency in district heating and barriers to technology proliferation. From a long-term perspective, land use changes, especially the progression of compact city plans, have the potential to offset the decrement in energy consumption that maintains the efficiency of district heating systems. An integrated model is developed in this paper based on building cohort analysis to evaluate the economic feasibility and environmental impact of introducing district heating systems to a long-term compact city plan. As applied to a case in the Soma Region of Fukushima, Japan, potential migration from the suburbs to the central station districts is simulated, where district heating based on gas-fired cogeneration is expected to be introduced. The results indicate that guided migration to produce concentrated centers of population can substantially increase the heat demand density, which supports a wider application of district heating systems and better low-carbon performance. These results are further discussed in relation to technology innovation and related policies. It is concluded that policies related to urban land use planning and energy management should be integrated and quantitatively evaluated over the long-term with the aim of supporting urban low-carbon sustainable development.

关键词： building stock     compact city     district heating     energy use     Fukushima    

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Expert networks as science-policy interlocutors in the implementation of a monitoring reporting and verification (MRV) system

Remi CHANDRAN, Tsuyoshi FUJITA, Minoru FUJII, Shuichi ASHINA, Kei GOMI, Rizaldi BOER, Muhammad ARDIANSYAH

《能源前沿（英文）》 2018年 第12卷 第3期   页码 376-388 doi: 10.1007/s11708-018-0559-x

摘要：

The Paris Agreement, which entered into effect in 2016, emphasizes a definite timeline for communicating and maintaining successive nationally determined contributions (NDCs) that it plans to achieve in addressing climate change. This calls for the development of a measurement, reporting and verification (MRV) system and a Capacity-building Initiative for Transparency (CBIT). Though such actions are universally accepted by the Parties to the Paris Agreement, earlier studies have shown that there remain technological, social, political and financial constrains which will affect the development and deployment of such a system. In this paper, using a case study on MRV implementation in Bogor City in Indonesia, how the above-mentioned challenges can be overcome is outlined through a technological and policy innovation process where scientists and technologists (collectively referred as expert networks) can join hands with local governments and national policy makers in designing, development and implementation of an MRV system that meets the local, national and global requirements. Through the case study it is further observed that expert networks can act as interactive knowledge generators and policy interlocutors in bridging technology with policy. To be specific, first, a brief history of the international context of MRV and CBIT is outlined. Next, the theoretical underpinning of the study is contextualized within the existing theories related to public policy and international relations. Finally, the case study is outlined and investigated where the engagement of an expert-network and policy makers in the design, development and implementation of an MRV tool is showcased.

关键词： MRV     CBIT     UNFCCC     Indonesia     Japan     ICT based monitoring     climate policy    

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Employing electricity-consumption monitoring systems and integrative time-series analysis models: A case study in Bogor, Indonesia

Seiya MAKI, Shuichi ASHINA, Minoru FUJII, Tsuyoshi FUJITA, Norio YABE, Kenji UCHIDA, Gito GINTING, Rizaldi

《能源前沿（英文）》 2018年 第12卷 第3期   页码 426-439 doi: 10.1007/s11708-018-0560-4

摘要：

The Paris Agreement calls for maintaining a global temperature less than 2°C above the pre-industrial level and pursuing efforts to limit the temperature increase even further to 1.5°C. To realize this objective and promote a low-carbon society, and because energy production and use is the largest source of global greenhouse-gas (GHG) emissions, it is important to efficiently manage energy demand and supply systems. This, in turn, requires theoretical and practical research and innovation in smart energy monitoring technologies, the identification of appropriate methods for detailed time-series analysis, and the application of these technologies at urban and national scales. Further, because developing countries contribute increasing shares of domestic energy consumption, it is important to consider the application of such innovations in these areas. Motivated by the mandates set out in global agreements on climate change and low-carbon societies, this paper focuses on the development of a smart energy monitoring system (SEMS) and its deployment in households and public and commercial sectors in Bogor, Indonesia. An electricity demand prediction model is developed for each device using the Auto-Regression eXogenous model. The real-time SEMS data and time-series clustering to explore similarities in electricity consumption patterns between monitored units, such as residential, public, and commercial buildings, in Bogor is, then, used. These clusters are evaluated using peak demand and Ramadan term characteristics. The resulting energy-prediction models can be used for low-carbon planning.

关键词： electricity monitoring     electricity demand prediction     multiple-variable time-series modeling     time-series cluster analysis     Indonesia    

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Carbon footprint assessment for the waste management sector: A comparative analysis of China and Japan

Lu SUN, Zhaoling LI, Minoru FUJII, Yasuaki HIJIOKA, Tsuyoshi FUJITA

《能源前沿（英文）》 2018年 第12卷 第3期   页码 400-410 doi: 10.1007/s11708-018-0565-z

摘要：

Waste management is becoming a crucial issue in modern society owing to rapid urbanization and the increasing generation of municipal solid waste (MSW). This paper evaluates the carbon footprint of the waste management sector to identify direct and indirect carbon emissions, waste recycling carbon emission using a hybrid life cycle assessment and input-output analysis. China and Japan was selected as case study areas to highlight the effects of different industries on waste management. The results show that the life cycle carbon footprints for waste treatment are 59.01 million tons in China and 7.01 million tons in Japan. The gap between these footprints is caused by the different waste management systems and treatment processes used in the two countries. For indirect carbon footprints, China’s material carbon footprint and depreciation carbon footprint are much higher than those of Japan, whereas the purchased electricity and heat carbon footprint in China is half that of Japan. China and Japan have similar direct energy consumption carbon footprints. However, CO2 emissions from MSW treatment processes in China (46.46 million tons) is significantly higher than that in Japan (2.72 million tons). The corresponding effects of waste recycling on CO2 emission reductions are considerable, up to 181.37 million tons for China and 96.76 million tons for Japan. Besides, measures were further proposed for optimizing waste management systems in the two countries. In addition, it is argued that the advanced experience that developed countries have in waste management issues can provide scientific support for waste treatment in developing countries such as China.

关键词： waste management     waste recycling     carbon footprint     hybrid LCA    

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Standard model of knowledge representation

Wensheng YIN

《机械工程前沿（英文）》 2016年 第11卷 第3期   页码 275-288 doi: 10.1007/s11465-016-0372-3

摘要：

Knowledge representation is the core of artificial intelligence research. Knowledge representation methods include predicate logic, semantic network, computer programming language, database, mathematical model, graphics language, natural language, etc. To establish the intrinsic link between various knowledge representation methods, a unified knowledge representation model is necessary. According to ontology, system theory, and control theory, a standard model of knowledge representation that reflects the change of the objective world is proposed. The model is composed of input, processing, and output. This knowledge representation method is not a contradiction to the traditional knowledge representation method. It can express knowledge in terms of multivariate and multidimensional. It can also express process knowledge, and at the same time, it has a strong ability to solve problems. In addition, the standard model of knowledge representation provides a way to solve problems of non-precision and inconsistent knowledge.

关键词： knowledge representation     standard model     ontology     system theory     control theory     multidimensional representation    

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受限空间火灾模型研究进展

郑昕,袁宏永

《中国工程科学》 2004年 第6卷 第3期   页码 68-74

摘要：

火灾模型是从工程科学的角度出发，分析研究火灾的发生、发展，烟气蔓延以及火灾对周围环境诸如建筑设备、森林植被及大气环境等影响的数学模型。介绍了广泛应用于建筑物内部受限空间的场、区域、网模型以及经验模型的理论思想与数学方程，分析了4种模型在相应环境下应用的合理性，并对火灾模型的发展做出了展望。

关键词： 受限空间     场模型     区域模型     网模型     场区网模型     经验模型    

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Elevated temperature creep model of parallel wire strands

《结构与土木工程前沿（英文）》   页码 1060-1071 doi: 10.1007/s11709-023-0981-y

摘要： Parallel wire strands (PWSs), which are widely used in prestressed steel structures, are typically in high-stress states. Under fire conditions, significant creep effects occur, reducing the prestress and influencing the mechanical behavior of PWSs. As there is no existing approach to analyze their creep behavior, this study experimentally investigated the elevated temperature creep model of PWSs. A charge-coupled camera system was incorporated to accurately obtain the deformation of the specimen during the elevated temperature creep test. It was concluded that the temperature level had a more significant effect on the creep strain than the stress level, and 450 °C was the key segment point where the creep rate varied significantly. By comparing the elevated temperature creep test results for PWSs and steel strands, it was found that the creep strain of PWSs was lower than that of steel strands at the same temperature and stress levels. The parameters in the general empirical formula, the Bailey–Norton model, and the composite time-hardening model were fitted based on the experimental results. By evaluating the accuracy and form of the models, the composite time-hardening model, which can simultaneously consider temperature, stress, and time, is recommended for use in the fire-resistance design of pre-tensioned structures with PWSs.

关键词： parallel wire strands     experimental study     elevated temperature creep model    

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Impact of crude distillation unit model accuracy on refinery production planning

Gang FU, Pedro A. Castillo CASTILLO, Vladimir MAHALEC

《工程管理前沿（英文）》 2018年 第5卷 第2期   页码 195-201 doi: 10.15302/J-FEM-2017052

摘要： In this work, we examine the impact of crude distillation unit (CDU) model errors on the results of refinery-wide optimization for production planning or feedstock selection. We compare the swing cut+ bias CDU model with a recently developed hybrid CDU model (Fu et al., 2016). The hybrid CDU model computes material and energy balances, as well as product true boiling point (TBP) curves and bulk properties (e.g., sulfur % and cetane index, and other properties). Product TBP curves are predicted with an average error of 0.5% against rigorous simulation curves. Case studies of optimal operation computed using a planning model that is based on the swing cut+ bias CDU model and using a planning model that incorporates the hybrid CDU model are presented. Our results show that significant economic benefits can be obtained using accurate CDU models in refinery production planning.

关键词： impact of model accuracy on production planning     swing cut+ bias CDU model     hybrid CDU model     refinery feedstock selection optimization     optimization of refinery operation    

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Test-driven verification/validation of model transformations

László LENGYEL,Hassan CHARAF

《信息与电子工程前沿（英文）》 2015年 第16卷 第2期   页码 85-97 doi: 10.1631/FITEE.1400111

摘要： Why is it important to verify/validate model transformations? The motivation is to improve the quality of the transformations, and therefore the quality of the generated software artifacts. Verified/validated model transformations make it possible to ensure certain properties of the generated software artifacts. In this way, verification/validation methods can guarantee different requirements stated by the actual domain against the generated/modified/optimized software products. For example, a verified/validated model transformation can ensure the preservation of certain properties during the model-to-model transformation. This paper emphasizes the necessity of methods that make model transformation verified/validated, discusses the different scenarios of model transformation verification and validation, and introduces the principles of a novel test-driven method for verifying/validating model transformations. We provide a solution that makes it possible to automatically generate test input models for model transformations. Furthermore, we collect and discuss the actual open issues in the field of verification/validation of model transformations.

关键词： Graph rewriting based model transformations     Verification/validation     Test-driven verification    

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Digital twin-assisted gearbox dynamic model updating toward fault diagnosis

《机械工程前沿（英文）》 2023年 第18卷 第2期 doi: 10.1007/s11465-023-0748-0

摘要： One of the core challenges of intelligent fault diagnosis is that the diagnosis model requires numerous labeled training datasets to achieve satisfactory performance. Generating training data using a virtual model is a potential solution for addressing such a problem, and the construction of a high-fidelity virtual model is fundamental and critical for data generation. In this study, a digital twin-assisted dynamic model updating method for fault diagnosis is thus proposed to improve the fidelity and reliability of a virtual model, which can enhance the generated data quality. First, a virtual model is established to mirror the vibration response of a physical entity using a dynamic modeling method. Second, the modeling method is validated through a frequency analysis of the generated signal. Then, based on the signal similarity indicator, a physical–virtual signal interaction method is proposed to dynamically update the virtual model in which parameter sensitivity analysis, surrogate technique, and optimization algorithm are applied to increase the efficiency during the model updating. Finally, the proposed method is successfully applied to the dynamic model updating of a single-stage helical gearbox; the virtual data generated by this model can be used for gear fault diagnosis.

关键词： digital twin     gearbox     model construction     model updating     physical–virtual interaction    

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Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

《能源前沿（英文）》 2015年 第9卷 第4期   页码 472-485 doi: 10.1007/s11708-015-0373-7

摘要： It is well recognized that the voltage stability of a power system is affected by the load model and hence, to effectively analyze the reactive power compensation of an isolated hybrid wind-diesel based power system, the loads need to be considered along with the generators in a transient analysis. This paper gives a detailed mathematical modeling to compute the reactive power response with small voltage perturbation for composite load. The composite load is a combination of the static and dynamic load model. To develop this composite load model, the exponential load is used as a static load model and induction motors (IMs) are used as a dynamic load model. To analyze the dynamics of IM load, the fifth, third and first order model of IM are formulated and compared using differential equations solver in Matlab coding. Since the decentralized areas have many small consumers which may consist large numbers of IMs of small rating, it is not realistic to model either a single large rating unit or all small rating IMs together that are placed in the system. In place of using a single large rating IM, a group of motors are considered and then the aggregate model of IM is developed using the law of energy conservation. This aggregate model is used as a dynamic load model. For different simulation studies, especially in the area of voltage stability with reactive power compensation of an isolated hybrid power system, the transfer function of the composite load is required. The transfer function of the composite load is derived in this paper by successive derivation for the exponential model of static load and for the fifth and third order IM dynamic load model using state space model.

关键词： isolated hybrid power system (IHPS)     composite load model     static load     dynamic load     induction motor load model     aggregate load    

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Initiation of Setaria as a model plant

Xianmin DIAO,James SCHNABLE,Jeffrey L. BENNETZEN,Jiayang LI

《农业科学与工程前沿（英文）》 2014年 第1卷 第1期   页码 16-20 doi: 10.15302/J-FASE-2014011

摘要： Model organisms such as Arabidopsis ( ) and rice ( ) have proven essential for efficient scientific discovery and development of new methods. With the diversity of plant lineages, some important processes such as C photosynthesis are not found in either Arabidopsis or rice, so new model species are needed. Due to their small diploid genomes, short life cycles, self-pollination, small adult statures and prolific seed production, domesticated foxtail millet ( ) and its wild ancestor, green foxtail ( ), have recently been proposed as novel model species for functional genomics of the Panicoideae, especially for study of C photosynthesis. This review outlines the development of these species as model organisms, and discusses current challenges and future potential of a Setaria model.

关键词： Setaria     foxtail millet     C4 photosynthesis     model organism    

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标题 作者 时间 类型 操作

Molecular dynamics study of water diffusion in an amphiphilic block copolymer with large difference in the blocks’ glass transition temperatures

Yang Zhou, Phillip Choi

期刊论文

Responding to the Paris Climate Agreement: global climate change mitigation efforts

Yong GENG, Tsuyoshi FUJITA, Anthony CHIU, Hancheng DAI, Han HAO

期刊论文

Proliferation of district heating using local energy resources through strategic building-stock management: A case study in Fukushima, Japan

Yi DOU, Keijiro OKUOKA, Minoru FUJII, Hiroki TANIKAWA, Tsuyoshi FUJITA, Takuya TOGAWA, Liang DONG

期刊论文

Expert networks as science-policy interlocutors in the implementation of a monitoring reporting and verification (MRV) system

Remi CHANDRAN, Tsuyoshi FUJITA, Minoru FUJII, Shuichi ASHINA, Kei GOMI, Rizaldi BOER, Muhammad ARDIANSYAH

期刊论文

Employing electricity-consumption monitoring systems and integrative time-series analysis models: A case study in Bogor, Indonesia

Seiya MAKI, Shuichi ASHINA, Minoru FUJII, Tsuyoshi FUJITA, Norio YABE, Kenji UCHIDA, Gito GINTING, Rizaldi

期刊论文

Carbon footprint assessment for the waste management sector: A comparative analysis of China and Japan

Lu SUN, Zhaoling LI, Minoru FUJII, Yasuaki HIJIOKA, Tsuyoshi FUJITA

期刊论文

Standard model of knowledge representation

Wensheng YIN

期刊论文

张正彦：融合知识的预训练语言模型（2020年4月3日）

2022年04月18日

会议视频

受限空间火灾模型研究进展

郑昕,袁宏永

期刊论文

Elevated temperature creep model of parallel wire strands

期刊论文

Impact of crude distillation unit model accuracy on refinery production planning

Gang FU, Pedro A. Castillo CASTILLO, Vladimir MAHALEC

期刊论文

Test-driven verification/validation of model transformations

László LENGYEL,Hassan CHARAF

期刊论文

Digital twin-assisted gearbox dynamic model updating toward fault diagnosis

期刊论文

Estimation of composite load model with aggregate induction motor dynamic load for an isolated hybrid

Nitin Kumar SAXENA,Ashwani Kumar SHARMA

期刊论文

Initiation of Setaria as a model plant

Xianmin DIAO,James SCHNABLE,Jeffrey L. BENNETZEN,Jiayang LI

期刊论文