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Series transformer based diode-bridge-type solid state fault current limiter

Amir HEIDARY,Hamid RADMANESH,Seyed Hamid FATHI,G. B. GHAREHPETIAN

《信息与电子工程前沿（英文）》 2015年 第16卷 第9期   页码 769-784 doi: 10.1631/FITEE.1400428

摘要： We propose a novel series transformer based diode-bridge-type solid state fault current limiter (SSFCL). To control the fault current, a series RLC branch is connected to the secondary side of an isolation series transformer. Based on this RLC branch, two current limiting modes are created. In the first mode, R and C are bypassed via a paralleled power electronic switch (insulated-gate bipolar transistor, IGBT) and L remains connected to the secondary side of the transformer as a DC reactor. In the second mode, the series reactor impedance is not enough to limit the fault current. In this case, the fault current can be controlled by selecting a proper on-off duration of the parallel IGBT, across the series damping resistor ( ) and capacitor, which inserts high impedance into the line to limit the fault current. Then, by controlling the magnitude of the DC reactor current, the fault current is reduced and the voltage of the point of common coupling (PCC) is kept at an acceptable level. In addition, in the new SSFCL, the series RC branch, connected in parallel with the IGBT, serves as a snubber circuit for decreasing the transient recovery voltage (TRV) of the IGBT during on-off states. Therefore, the power quality indices can be improved. The measurement results of a built prototype are presented to support the simulation and theoretical studies. The proposed SSFCL can limit the fault current without any delay and successfully smooth the fault current waveform.

关键词： Solid state fault current limiter (SSFCL)     Power quality     Voltage sag     Point of common coupling (PCC)     Isolation transformer    

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Advances in some common chronic liver diseases

null

《医学前沿（英文）》 2014年 第8卷 第2期   页码 127-128 doi: 10.1007/s11684-014-0341-3

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Top-geoherbs of traditional Chinese medicine: common trait, quality characteristics and formation

Luqi Huang, Lanping Guo, Chaoyi Ma, Wei Gao, Qingjun Yuan

《医学前沿（英文）》 2011年 第5卷 第2期   页码 185-194 doi: 10.1007/s11684-011-0141-y

摘要： Top-geoherbs used in China are always featured with high qualities, and they grow in specified areas with specific environment. Recently, researches on top-geoherbs have attracted increasing attention in China and other countries. In order to have a thorough knowledge of top-geoherbs, this article reviews the concept, historical evolution, common trait and quality characteristics of top-geoherbs, and explains the forming mechanism including genetic mechanism and environmental mechanism. In addition, it introduces the influence of human factors on the quality of top-geoherbs. Finally, it proposes some problems that should be paid attention to in the researches on top-geoherbs.

关键词： top-geoherbs     common trait     quality characteristics     formation     biological mechanism    

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Microdamage study of granite under thermomechanical coupling based on the particle flow code

《结构与土木工程前沿（英文）》   页码 1413-1427 doi: 10.1007/s11709-023-0953-2

摘要： The thermomechanical coupling of rocks refers to the interaction between the mechanical and thermodynamic behaviors of rocks induced by temperature changes. The study of this coupling interaction is essential for understanding the mechanical and thermodynamic properties of the surrounding rocks in underground engineering. In this study, an improved temperature-dependent linear parallel bond model is introduced under the framework of a particle flow simulation. A series of numerical thermomechanical coupling tests are then conducted to calibrate the micro-parameters of the proposed model by considering the mechanical behavior of the rock under different thermomechanical loadings. Good agreement between the numerical results and experimental data are obtained, particularly in terms of the compression, tension, and elastic responses of granite. With this improved model, the thermodynamic response and underlying cracking behavior of a deep-buried tunnel under different thermal loading conditions are investigated and discussed in detail.

关键词： thermomechanical coupling effect     granite     improved linear parallel bond model     thermal property     particle flow code    

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AGCD: a robust periodicity analysis method based on approximate greatest common divisor

Juan YU,Pei-zhong LU

《信息与电子工程前沿（英文）》 2015年 第16卷 第6期   页码 466-473 doi: 10.1631/FITEE.1400345

摘要： Periodicity is one of the most common phenomena in the physical world. The problem of periodicity analysis (or period detection) is a research topic in several areas, such as signal processing and data mining. However, period detection is a very challenging problem, due to the sparsity and noisiness of observational datasets of periodic events. This paper focuses on the problem of period detection from sparse and noisy observational datasets. To solve the problem, a novel method based on the approximate greatest common divisor (AGCD) is proposed. The proposed method is robust to sparseness and noise, and is efficient. Moreover, unlike most existing methods, it does not need prior knowledge of the rough range of the period. To evaluate the accuracy and efficiency of the proposed method, comprehensive experiments on synthetic data are conducted. Experimental results show that our method can yield highly accurate results with small datasets, is more robust to sparseness and noise, and is less sensitive to the magnitude of period than compared methods.

关键词： Periodicity analysis     Period detection     Sparsity     Noise     Approximate greatest common divisor (AGCD)    

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Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 78-98 doi: 10.1007/s11709-022-0936-8

摘要： For localized fires, it is necessary to consider the thermal and mechanical responses of building elements subject to uneven heating under the influence of wind. In this paper, the thermomechanical phenomena experienced by a ceiling jet and I-beam in a structural fire were simulated. Instead of applying the concept of adiabatic surface temperature (AST) to achieve fluid–structure coupling, this paper proposes a new computational fluid dynamics–finite element method numerical simulation that combines wind, fire, thermal, and structural analyses. First, to analyze the velocity and temperature distributions, the results of the numerical model and experiment were compared in windless conditions, showing good agreement. Vortices were found in the local area formed by the upper and lower flanges of the I-beam and the web, generating a local high-temperature zone and enhancing the heat transfer of convection. In an incoming-flow scenario, the flame was blown askew significantly; the wall temperature was bimodally distributed in the axial direction. The first temperature peak was mainly caused by radiative heat transfer, while the second resulted from convective heat transfer. In terms of mechanical response, the yield strength degradation in the highest-temperature region in windless conditions was found to be significant, thus explaining the stress distribution of steel beams in the fire field. The mechanical response of the overall elements considering the incoming flows was essentially elastic.

关键词： CFD–FEM coupling     steel beam     wind     ceiling jet     numerical heat transfer    

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Influence of cetane number improver on performance and emissions of a common-rail diesel engine fueled

Wu YU, Gen CHEN, Zuohua HUANG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 412-418 doi: 10.1007/s11708-011-0163-9

摘要： In this paper, the effect of cetane number (CN) improver on performance and emissions, including particulate number concentration and size distribution, of a turbocharged, common-rail diesel engine fueled with biodiesel-methanol were studied. Two volume fractions (0.3% and 0.6%) of CN improver were added to BM30 (30% of methanol in the biodiesel-methanol blend) in the experiment. The results show that, compared with those of biodiesel-methanol blend, the peak value of cylinder pressure increases, the second peak of heat release rate decreases, the start of second heat release are advanced, and the fuel economy and thermal efficiency are improved when CN improver is added to biodiesel-methanol blend. Besides, CO and HC emissions decrease, NO emission varies little and smoke emissions increase slightly. Moreover, exhaust particles of BM30 mainly distribute in nano-size range. Furthermore, particle number concentration decreases and peak of size distribution profile shifts toward large size direction.

关键词： biodiesel     methanol     common-rail (CR) diesel engine     cetane number (CN) improver    

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Optimization of urban bus operation frequency under common route condition with rail transit

Bin YU, Sijia REN, Enze WU, Yifan ZHOU, Yunpeng WANG

《工程管理前沿（英文）》 2017年 第4卷 第4期   页码 451-462 doi: 10.15302/J-FEM-2017036

摘要： The overlap of bus and rail transit routes is common in China. This overlap provides passengers multiple choices for one trip. However, the availability of multiple options would cause uncertainty in the travel distribution of passengers. Given that buses and rail transits are becoming increasingly common, this paper aims to present the overlapped operation condition of bus and rail transit using a bi-level model from the perspective of bus operators. Frequency optimization model is established in the upper-level model. A heuristic algorithm called shuffled complex evolution (SCE-UA) method is used to solve the established frequency optimization model, and three other heuristic methods are compared with SCE-UA. A lower-level Logit model based on Agent simulation is set for traffic mode split. Data on the transit system in Dalian city are chosen as an example to test the feasibility of the model and the algorithm. Results show that as the overlapped optimization of bus route and rail transit routes changed primary bus frequency, the use of SCE-UA to solve such problems has evident advantages and feasibility; furthermore, changed bus frequency would improve bus operations.

关键词： common route     bus operation frequency     bi-level model     Agent simulation     SCE-UA algorithm    

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catalysts derived from zeolitic imidazolate framework@MXene composites for efficient oxidative self-coupling

《化学科学与工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11705-023-2378-9

摘要： In this study, we synthesize a catalyst comprising cobalt nanoparticles supported on MXene by pyrolyzing a composite in a N2 environment. Specifically, the composite comprises a bimetallic Zn/Co zeolitic imidazole framework grown in situ on the outer surface of MXene. The catalytic efficiency of the catalyst is tested for the self-coupling of 4-methoxybenzylamine to produce value-added imine, where atmospheric oxygen (1 atm) is used as the oxidant. Based on the results, the catalyst displayed impressive catalytic activity, achieving 95.4% yield of the desired imine at 383 K for 8 h. Furthermore, the catalyst showed recyclability and tolerance toward benzylamine substrates with various functional groups. The outstanding performance of the catalyst is primarily attributed to the synergetic catalytic effect between the cobalt nanoparticles and MXene support, while also benefiting from the three-dimensional porous structure. Additionally, a preliminary investigation of potential reaction mechanisms is conducted.

关键词： MXene     sacrificial template     oxidative self-coupling     Co nanoparticles     imine    

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Effects of nano-silicon and common silicon on lead uptake and translocation in two rice cultivars

Jianguo LIU,Hui CAI,Congcong MEI,Mingxin WANG

《环境科学与工程前沿（英文）》 2015年 第9卷 第5期   页码 905-911 doi: 10.1007/s11783-015-0786-x

摘要： The current study investigated the effects of nano-silicon (Si) and common Si on lead (Pb) toxicity, uptake, translocation, and accumulation in the rice cultivars Yangdao 6 and Yu 44 grown in soil containing two different Pb levels (500 mg·kg and 1000 mg·kg ). The results showed that Si application alleviated the toxic effects of Pb on rice growth. Under soil Pb treatments of 500 and 1000 mg·kg , the biomasses of plants supplied with common Si and nano-Si were 1.8%–5.2% and 3.3%–11.8% higher, respectively, than those of plants with no Si supply (control). Compared to the control, Pb concentrations in rice shoots supplied with common Si and nano-Si were reduced by 14.3%–31.4% and 27.6%–54.0%, respectively. Pb concentrations in rice grains treated with common Si and nano-Si decreased by 21.3%–40.9% and 38.6%–64.8%, respectively. Pb translocation factors (TFs) from roots to shoots decreased by 15.0%–29.3% and 25.6%–50.8%, respectively. The TFs from shoots to grains reduced by 8.3%–13.7% and 15.3%–21.1%, respectively, after Si application. The magnitudes of the effects observed on plants decreased in the following order: nano-Si treatment>common Si treatment and high-grain-Pb-accumulating cultivar (Yangdao 6)>low-grain-Pb-accumulating cultivar (Yu 44) and heavy Pb stress (1000 mg·kg )>moderate Pb stress (500 mg·kg )>no Pb treatment. The results of the study indicate that nano-Si is more efficient than common Si in ameliorating the toxic effects of Pb on rice growth, preventing Pb transfer from rice roots to aboveground parts, and blocking Pb accumulation in rice grains, especially in high-Pb-accumulating rice cultivars and in heavily Pb-polluted soils.

关键词： silicon (Si)     lead (Pb)     rice (Oryza sativa L.)     toxicity     accumulation    

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Effect of alkyl nitrite decomposition on catalytic performance of CO coupling reaction over supported

Zhenhua LI, Weihan WANG, Dongxue YIN, Jing LV, Xinbin MA

《化学科学与工程前沿（英文）》 2012年 第6卷 第4期   页码 410-414 doi: 10.1007/s11705-012-1213-5

摘要： The syntheses of dimethyl oxalate (DMO) and diethyl oxalate (DEO) by CO coupling reaction in gaseous phase were investigated in a fixed bed reactor over Pd-Fe/Al O catalyst. The catalytic performance was characterized by CO conversion, space-time yield (STY) and selectivity of DMO (or DEO). The results showed that over Pd-Fe/Al O catalyst, the STY of DMO was higher than that of DEO under the same reaction conditions. The optimum reaction temperatures for synthesizing DMO and DEO were 403 K and 393 K, respectively, at the molar ratio 1 ∶ 1 of alkyl nitrite to CO. The difference in synthesizing DMO and DEO on the same catalyst was attributed to the decomposition performances of methyl nitrite (MN) and ethyl nitrite (EN), as density functional theory (DFT) calculation showed that EN decomposed more easily than MN.

关键词： palladium     CO coupling     dialkyl oxalate     alkyl nitrite     decomposition    

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Thermodynamic and economic analyses of a coal and biomass indirect coupling power generation system

Buqing YE, Rui ZHANG, Jin CAO, Bingquan SHI, Xun ZHOU, Dong LIU

《能源前沿（英文）》 2020年 第14卷 第3期   页码 590-606 doi: 10.1007/s11708-020-0809-6

摘要： The coal and biomass coupling power generation technology is considered as a promising technology for energy conservation and emission reduction. In this paper, a novel coal and biomass indirect coupling system is proposed based on the technology of biomass gasification and co-combustion of coal and gasification gas. For the sake of comparison, a coal and biomass direct coupling system is also introduced based on the technology of co-combustion of coal and biomass. The process of the direct and the indirect coupling system is simulated. The thermodynamic and economic performances of two systems are analyzed and compared. The simulation indicates that the thermodynamic performance of the indirect coupling system is slightly worse, but the economic performance is better than that of the direct coupling system. When the blending ratio of biomass is 20%, the energy and exergy efficiencies of the indirect coupling system are 42.70% and 41.14%, the internal rate of return (IRR) and discounted payback period (DPP) of the system are 25.68% and 8.56 years. The price fluctuation of fuels and products has a great influence on the economic performance of the indirect coupling system. The environmental impact analysis indicates that the indirect coupling system can inhibit the propagation of NO and reduce the environmental cost.

关键词： biomass     indirect coupling system     process simulation     thermodynamic analysis     economic analysis    

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Dibutyl phthalate adsorption characteristics using three common substrates in aqueous solutions

Tiancui Li, Yaocheng Fan, Deshou Cun, Yanran Dai, Wei Liang

《环境科学与工程前沿（英文）》 2020年 第14卷 第2期 doi: 10.1007/s11783-019-1205-5

摘要： • DBP adsorption was tested using three kinds of substrates in constructed wetlands. • The DBP adsorption capacity followed the order: steel slag>gravel>shell sand. • High temperatures increased the DBP adsorption capacity in the substrates. • DOM consistently inhibited the DBP adsorption onto steel slag and gravel. In recent years, the presence and adverse impacts of phthalic acid esters in aquatic environments have gained increasing attention. This work investigated the adsorption behavior of a typical phthalic acid ester, dibutyl phthalate (DBP), onto steel slag, gravel, and shell sand (substrates commonly used in constructed wetlands). The influence of dissolved organic matter (DOM) on DBP adsorption was investigated using humic acid as a proxy for DOM. The results demonstrated that the adsorption of DBP to three substrates reached equilibrium within 96 h, and the adsorption kinetics were well fitted by a pseudo-second-order model. The DBP adsorption isotherms were best fitted by the Langmuir adsorption model. The DBP adsorption capacity decreased in the order of steel slag>gravel>shell sand, with values of 656 mg/kg, 598 mg/kg, and 6.62 mg/kg at 25°C, respectively. DBP adsorbed to the surface of all substrates in a monolayer via an endothermic process. The DBP adsorption capacities of steel slag and gravel decreased as the DOM content increased. The DBP adsorption mechanisms to steel slag and gravel mainly involved the surface coordination of DBP with –OH or –COOH groups and electrostatic interactions. The results of this work suggest that steel slag and gravel may be ideal substrates for use in constructed wetlands to treat wastewater polluted with DBP.

关键词： Adsorption     Dibutyl phthalate (DBP)     Dissolved organic matter     Substrates    

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Agriculture Green Development in China and the UK: common objectives and converging policy pathways

Yuelai LU, David NORSE, David POWLSON

《农业科学与工程前沿（英文）》 2020年 第7卷 第1期   页码 98-105 doi: 10.15302/J-FASE-2019298

摘要：

This paper has three aims. First, to examine how the negative environmental consequences of intensive agriculture have driven China and the UK to shift away from narrowly focused farm output policies and adopt more holistic green development pathways. Second, to explore the policy objectives they have in common. Third, to assess the numerous opportunities for joint research and knowledge sharing through the Sustainable Agriculture Innovation Network and other existing institutional mechanisms. The intensification of agricultural production in the UK started several decades earlier than in China as did the negative environmental consequences of the farm practices. However, their strategies and policies for sustainable intensification and green development have much in common. These are set out in two main documents: the Chinese State Council guidelines for green agriculture and the UK Department for Environment, Food and Rural Affairs 25 Year Environment Plan. There are substantial mutual advantages from greater collaboration on problem identification and monitoring; the development of appropriate technological and management responses and the formulation of sound policies. To achieve this potential, it is recommended that further thought be given to how best to bring together all of the key stakeholders along the whole food chain.

关键词： Agriculture Green Development     China     policy     UK    

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STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT

《农业科学与工程前沿（英文）》 2023年 第10卷 第4期   页码 503-509 doi: 10.15302/J-FASE-2023528

摘要：

STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT

关键词： GREEN     AGRICULTURAL     PROMOTE     POLLUTION     SOURCE     DEVELOPMENT     POINT     STRENGTHENING     CONTROL    

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标题 作者 时间 类型 操作

Series transformer based diode-bridge-type solid state fault current limiter

Amir HEIDARY,Hamid RADMANESH,Seyed Hamid FATHI,G. B. GHAREHPETIAN

期刊论文

Advances in some common chronic liver diseases

null

期刊论文

Top-geoherbs of traditional Chinese medicine: common trait, quality characteristics and formation

Luqi Huang, Lanping Guo, Chaoyi Ma, Wei Gao, Qingjun Yuan

期刊论文

Microdamage study of granite under thermomechanical coupling based on the particle flow code

期刊论文

AGCD: a robust periodicity analysis method based on approximate greatest common divisor

Juan YU,Pei-zhong LU

期刊论文

Simulation of steel beam under ceiling jet based on a wind–fire–structure coupling model

期刊论文

Influence of cetane number improver on performance and emissions of a common-rail diesel engine fueled

Wu YU, Gen CHEN, Zuohua HUANG

期刊论文

Optimization of urban bus operation frequency under common route condition with rail transit

Bin YU, Sijia REN, Enze WU, Yifan ZHOU, Yunpeng WANG

期刊论文

catalysts derived from zeolitic imidazolate framework@MXene composites for efficient oxidative self-coupling

期刊论文

Effects of nano-silicon and common silicon on lead uptake and translocation in two rice cultivars

Jianguo LIU,Hui CAI,Congcong MEI,Mingxin WANG

期刊论文

Effect of alkyl nitrite decomposition on catalytic performance of CO coupling reaction over supported

Zhenhua LI, Weihan WANG, Dongxue YIN, Jing LV, Xinbin MA

期刊论文

Thermodynamic and economic analyses of a coal and biomass indirect coupling power generation system

Buqing YE, Rui ZHANG, Jin CAO, Bingquan SHI, Xun ZHOU, Dong LIU

期刊论文

Dibutyl phthalate adsorption characteristics using three common substrates in aqueous solutions

Tiancui Li, Yaocheng Fan, Deshou Cun, Yanran Dai, Wei Liang

期刊论文

Agriculture Green Development in China and the UK: common objectives and converging policy pathways

Yuelai LU, David NORSE, David POWLSON

期刊论文

STRENGTHENING NON-POINT SOURCE POLLUTION CONTROL TO PROMOTE AGRICULTURAL GREEN DEVELOPMENT

期刊论文