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Simulation of cross-flow-induced vibration of tube bundle by surface vorticity method

WANG Fenghao, JIANG Gedong, Lin John Zhang

《能源前沿(英文)》 2008年 第2卷 第3期   页码 243-248 doi: 10.1007/s11708-008-0049-7

摘要: A fluid-structure interaction model based on Surface Vorticity Method (SVM) was used to study flow-induced vibrations of tube bundles in medium space ratio. The flow-induced vibrations of four tubes in a rotated square and a staggered tube bundle in three-row and five-column arrangements were simulated in the high sub-critical Reynolds number () range. The results on fluid forces, tube responses and vorticity maps were presented. The vorticity maps of the four rotated-square tubes changed dramatically when the rigid tubes were replaced by the flexible tubes. From the vorticity maps and vibration responses of the staggered tube bundle of different structural parameters, it was found that with the decrease of tube natural frequency, the maximal vibration response moved from the third row to the first. The results also showed that when more flexible tubes are used, the flow pattern changed drastically and the fluid-structure interaction imposed a dominant impact on the flow.

关键词: dominant     sub-critical Reynolds     staggered     Vorticity     three-row    

China ADS sub-critical experimental assembly—Venus-1 and preliminary experiment

SHI Yongqian, XIA Pu, LUO Zhanglin, ZHAO Zhixiang, DING Dazhao, ZHU Qinfu, XIA Haihong, LI Jigen, ZHANG Wei, CAO Jian, QUAN Yanhui, LUO Huangda, WU Xiaofei

《能源前沿(英文)》 2007年 第1卷 第2期   页码 150-157 doi: 10.1007/s11708-007-0019-5

摘要: China s accelerator-driven sub-critical system (ADS) sub-critical experimental assembly Venus-1 and the preliminary experiment is presented. The core of Venus-1 is a coupled one of a fast neutron zone and a thermal neutron zone. The fast neutron zone is at the centre of the core and formed by natural uranium fuel. A fast neutron spectrum field can be produced in the fast neutron zone and used for the transmutation of minor actinides (MAs). The thermal neutron zone surrounds the fast neutron zone and is formed by low-enriched uranium fuel. It is a fission zone. An epithermal neutron zone between the fast neutron zone and the thermal neutron zone can be established for the transmutation of long-lived fission products (LLFP). On July 18, 2005, the first fuel element was loaded into the Venus-1 sub-critical assembly and some preliminary experiments about the sub-critical neutronics were performed. The Venus-1 can be driven by an Am-Be source or other steady neutron source (Cf-252, D-D reaction and D-T reaction) to study the effect of the external neutron source with different energies or a D-T pulsed neutron source on the dynamic characteristics.

关键词: coupled     D-D reaction     dynamic     pulsed neutron     sub-critical assembly    

An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical sliding-pressure operation once-through boiler

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

《能源前沿(英文)》 2007年 第1卷 第3期   页码 300-304 doi: 10.1007/s11708-007-0043-5

摘要: Within the pressure range of 9–28 MPa, mass velocity range of 600–1 200 kg/(m · s), and heat flux range of 200–500 kW/m, experiments were performed to investigate the heat transfer to water in the inclined upward internally ribbed tube with an inclined angle of 19.5 degrees, a maximum outer diameter of 38.1 mm, and a thickness of 7.5 mm. Based on the experiments, it was found that heat transfer enhancement of the internally ribbed tube could postpone departure from nucleate boiling at the sub-critical pressure. However, the heat transfer enhancement decreased near the critical pressure. At supercritical pressure, the temperature difference between the wall and the fluid increased near the pseudo-critical temperature, but the increase of wall temperature was less than that of departure from nucleate boiling at sub-critical pressure. When pressure is closer to the critical pressure, the temperature difference between the wall and the fluid increased greatly near the pseudo-critical temperature. Heat transfer to supercritical water in the inclined upward internally ribbed tube was enhanced or deteriorated near the pseudo-critical temperature with the variety of ratio between the mass velocity and the heat flux. Because the rotational flow of the internal groove reduced the effect of natural convection, the internal wall temperature of internally ribbed tube uniformly distributed along the circumference. The maximum internal wall temperature difference of the tube along the circumference was only 10 degrees when the fluid enthalpy exceeded 2 000 J/g. Considering the effect of acute variety of the fluid property on heat transfer, the correlation of heat transfer coefficient on the top of the internally ribbed tube was provided.

关键词: m ·     diameter     critical pressure     sub-critical pressure     maximum    

The summary of researches on ADS in China

XIA Haihong, ZHAO Zhixiang, LI Jigen, SHI Yongqian, HAN Yinlu, ZHU Shengyun, XU Yongli, GUAN Xialing, CUI Baoqun, FU Shinian

《能源前沿(英文)》 2007年 第1卷 第2期   页码 135-140 doi: 10.1007/s11708-007-0017-7

摘要: The conceptual study on the accelerator driven system (ADS) that lasted for about five years ended in 1999 in China. As one project of the National Basic Research Program of China (973 Program) in the energy domain, which is sponsored by the China Ministry of Science and Technology (MOST), a five-year-program of fundamental research of ADS physics and related technology was launched in 2000 and passed national review at the end of 2005. The China Institute of Atomic Energy (CIAE), the Institute of High Energy Physics (IHEP), the Institute of Heavy Ion Physics in Peking University (PKU-IHIP) and other institutions jointly carried out the research. The research activities were focused on HPPA physics and technology, reactor physics of external source driven sub-critical assembly, nuclear data base and material study. For HPPA, a high current injector consisting of an ECR ion source, LEBT and an RFQ accelerating structure of 3.5 MeV was built. In reactor physics study, a series of neutron multiplication experimental study has been carried out and still being done. The VENUS facility has been constructed as the basic experimental platform for neutronics study in ADS blanket. It s a zero power sub-critical neutron multiplying assembly driven by external neutron produced by a pulsed neutron generator. The theoretical, experimental and simulation study on nuclear data, material properties and nuclear fuel circulation related to ADS is carrying on to provide the database for ADS system analysis. The main results on ADS related researches will be reported.

关键词: accelerator     national     multiplying assembly     sub-critical assembly     simulation    

Greenhouse gas emissions from different pig manure management techniques: a critical analysis

Conor Dennehy, Peadar G. Lawlor, Yan Jiang, Gillian E. Gardiner, Sihuang Xie, Long D Nghiem, Xinmin Zhan

《环境科学与工程前沿(英文)》 2017年 第11卷 第3期 doi: 10.1007/s11783-017-0942-6

摘要: Manure management is the primary source of greenhouse gas (GHG) emissions from pig farming, which in turn accounts for 18% of the total global GHG emissions from the livestock industry. In this review, GHG emissions (N O and CH emissions in particular) from individual pig manure (PGM) management practices (European practises in particular) are systematically analyzed and discussed. These manure management practices include manure storage, land application, solid/liquid separation, anaerobic digestion, composting and aerobic wastewater treatment. The potential reduction in net GHG emissions by changing and optimising these techniques is assessed. This review also identifies key research gaps in the literature including the effect of straw covering of liquid PGM storages, the effect of solid/liquid separation, and the effect of dry anaerobic digestion on net GHG emissions from PGM management. In addition to identifying these research gaps, several recommendations including the need to standardize units used to report GHG emissions, to account for indirect N O emissions, and to include a broader research scope by conducting detailed life cycle assessment are also discussed. Overall, anaerobic digestion and compositing to liquid and solid fractions are best PGM management practices with respect to their high GHG mitigation potential.

关键词: CH4     N2O     Storage     Anaerobic digestion     Composting     Separation    

Numerical simulation of fluid dynamics in the stirred tank by the SSG Reynolds Stress Model

Nana QI, Hui WANG, Kai ZHANG, Hu ZHANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 506-514 doi: 10.1007/s11705-010-0508-7

摘要: The Speziale, Sarkar and Gatski Reynolds Stress Model (SSG RSM) is utilized to simulate the fluid dynamics in a full baffled stirred tank with a Rushton turbine impeller. Four levels of grid resolutions are chosen to determine an optimised number of grids for further simulations. CFD model data in terms of the flow field, trailing vortex, and the power number are compared with published experimental results. The comparison shows that the global fluid dynamics throughout the stirred tank and the local characteristics of trailing vortices near the blade tips can be captured by the SSG RSM. The predicted mean velocity components in axial, radial and tangential direction are also in good agreement with experiment data. The power number predicted is quite close to the designed value, which demonstrates that this model can accurately calculate the power number in the stirred tank. Therefore, the simulation by using a combination of SSG RSM and MRF impeller rotational model can accurately model turbulent fluid flow in the stirred tank, and it offers an alternative method for design and optimisation of stirred tanks.

关键词: stirred tank     fluid dynamics     numerical simulation     SSG Reynolds Stress Model     MRF    

Convective heat transfer in helical coils for constant-property and variable-property flows with high Reynolds

Yufei MAO, Liejin GUO, Bofeng BAI, Ximin ZHANG

《能源前沿(英文)》 2010年 第4卷 第4期   页码 546-552 doi: 10.1007/s11708-010-0116-8

摘要: Forced convection heat transfer of single-phase water in helical coils was experimentally studied. The testing section was constructed from a stainless steel round tube with an inner diameter of 10 mm, coil diameter of 300 mm, and pitch of 50 mm. The experiments were conducted over a wide Reynolds number range of 40000 to 500000. Both constant-property flows at normal pressure and variable-property flows at supercritical pressure were investigated. The contribution of secondary flow in the helical coil to heat transfer was gradually suppressed with increasing Reynolds number. Hence, heat transfer coefficients of the helical tube were close to those of the straight tube under the same flow conditions when the Reynolds number is large enough. Based on the experimental data, heat transfer correlations for both incompressible flows and supercritical fluid flows through helical coils were proposed.

关键词: convective heat transfer     helical coils     high Reynolds number     supercritical pressure     variable property    

Biodiesel production from waste frying oil in sub- and supercritical methanol on a zeolite Y solid acid

Jorge MEDINA-VALTIERRA, Jorge RAMIREZ-ORTIZ

《化学科学与工程前沿(英文)》 2013年 第7卷 第4期   页码 401-407 doi: 10.1007/s11705-013-1354-1

摘要: Waste frying oil (WFO) is a very important feedstock for obtaining biodiesel at low cost and using WFO in transesterification reactions to produce biodiesel helps eliminate local environmental problems. In this study biodiesel was produced from WFO in sub- and super-critical methanol on a zeolite Y solid acid catalyst. The procedure was optimized using a design of experiments by varying the methanol to WFO molar ratio, the reaction temperature, and the amount of catalyst. Typical biodiesel yields varied from 83 to nearly 100% with methyl esters content ranging from 1.41–1.66 mol·L and typical dynamic viscosities of 22.1-8.2 cP. Gas chromatography was used to determine the molecular composition of the biodiesel. The reaction products contained over 82 wt-% methyl esters, 4.2 wt-% free acids, 13.5 wt-% monoglycerides, and 0.3 wt-% diglycerides. The transesterification of WFO with methanol around its critical temperature combined with a zeolite Y as an acid catalyst is an efficient approach for the production of biodiesel with acceptable yields.

关键词: biodiesel     methanol     critical temperature     waste frying oil     zeolite Y    

Microbial biodegradation of plastics: Challenges, opportunities, and a critical perspective

《环境科学与工程前沿(英文)》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1596-6

摘要:

● Health hazards of plastic waste on environment are discussed.

关键词: Plastic-waste     Polymers     Health-hazards     Biodegradation     Microorganisms     Enzymes    

Numerical analysis of aerodynamic noise radiated from cross flow fan

CHEN Anbang, LI Song, HUANG Dongtao

《能源前沿(英文)》 2008年 第2卷 第4期   页码 443-447 doi: 10.1007/s11708-008-0063-9

摘要: The flow field in a cross flow fan was simulated by solving the 2-D unsteady Reynolds-averaged Navier-Stokes equations. The calculated pressure fluctuations of the blades, the vortex wall, and the rear wall were then used as noise sources to calculate the sound field. The Ffowcs Williams-Hawkings (FW-H) equation was employed to predict the noise field caused by these sources. The predictions show that the rear wall and the vortex wall sources contribute significantly to the total noise and that both the predicted aerodynamic performance and noise agree well with the experimental results.

关键词: predicted aerodynamic     Williams-Hawkings     calculated pressure     aerodynamic performance     unsteady Reynolds-averaged    

Machine learning in building energy management: A critical review and future directions

《工程管理前沿(英文)》 2022年 第9卷 第2期   页码 239-256 doi: 10.1007/s42524-021-0181-1

摘要: Over the past two decades, machine learning (ML) has elicited increasing attention in building energy management (BEM) research. However, the boundary of the ML-BEM research has not been clearly defined, and no thorough review of ML applications in BEM during the whole building life-cycle has been published. This study aims to address this gap by reviewing the ML-BEM papers to ascertain the status of this research area and identify future research directions. An integrated framework of ML-BEM, composed of four layers and a series of driving factors, is proposed. Then, based on the hype cycle model, this paper analyzes the current development status of ML-BEM and tries to predict its future development trend. Finally, five research directions are discussed: (1) the behavioral impact on BEM, (2) the integration management of renewable energy, (3) security concerns of ML-BEM, (4) extension to other building life-cycle phases, and (5) the focus on fault detection and diagnosis. The findings of this study are believed to provide useful references for future research on ML-BEM.

关键词: building energy management     machine learning     integrated framework     knowledge evolution    

通过一个等价雷诺数揭示层流到湍流的转捩区域 Article

陈晓东

《工程(英文)》 2019年 第5卷 第3期   页码 576-579 doi: 10.1016/j.eng.2018.09.013

摘要:

Flow transition from laminar to turbulent mode (and vice versa)—that is, the initiation of turbulence—is one of the most important research subjects in the history of engineering. Even for pipe flow, predicting the onset of turbulence requires sophisticated instrumentation and/or direct numerical simulation, based on observing the instantaneous flow structure formation and evolution. In this work, a local Reynolds number equivalence γ (ratio of local inertia effect to viscous effect) is seen to conform to the Universal Law of the Wall, where γ = 1 represents a quantitative balance between the abovementioned two effects. This coincides with the wall layer thickness (y+ = 1, where y+ is the dimensionless distance from the wall surface defined in the Universal Law of the Wall). It is found that the characteristic of how the local derivative of γ against the local velocity changes with increasing velocity determines the onset of turbulence. For pipe flow, γ  25, and for plate flow, γ 151.5. These findings suggest that a certain combination of γ and velocity (nonlinearity) can qualify the source of turbulence (i.e., generate turbulent energy). Similarly, a re-evaluation of the previous findings reveals that only the geometrically narrow domain can act locally as the source of turbulence, with the rest of the flow field largely being left for transporting and dissipating. This understanding will have an impact on the future large-scale modeling of turbulence.

关键词: 局部等价雷诺数     转捩     壁面律     管流     平板流动     建模    

Reducing environmental impacts through socioeconomic transitions: critical review and prospects

《环境科学与工程前沿(英文)》 2023年 第17卷 第2期 doi: 10.1007/s11783-023-1624-1

摘要:

● Reducing environmental impacts through socioeconomic structural transitions.

关键词: Environmental pressures     Environmental impacts     Nexus     Supply chains     Trade     Coupled systems    

Advances in airborne microorganisms detection using biosensors: A critical review

《环境科学与工程前沿(英文)》 2021年 第15卷 第3期 doi: 10.1007/s11783-021-1420-8

摘要:

Humanity has been facing the threat of a variety of infectious diseases. Airborne microorganisms can cause airborne infectious diseases, which spread rapidly and extensively, causing huge losses to human society on a global scale. In recent years, the detection technology for airborne microorganisms has developed rapidly; it can be roughly divided into biochemical, immune, and molecular technologies.

关键词: Biosensor     Airborne microorganisms     Microbiological detection technology    

Iteration framework for solving mixed lubrication computation problems

《机械工程前沿(英文)》 2021年 第16卷 第3期   页码 635-648 doi: 10.1007/s11465-021-0632-8

摘要: The general discrete scheme of time-varying Reynolds equation loses the information of the previous step, which makes it unreasonable. A discretization formula of the Reynolds equation, which is based on the Crank–Nicolson method, is proposed considering the physical message of the previous step. Gauss–Seidel relaxation and distribution relaxation are adopted for the linear operators of pressure during the numerical solution procedure. In addition to the convergent criteria of pressure distribution and load, an estimation framework is developed to investigate the relative error of the most important term in the Reynolds equation. Smooth surface with full contacts and mixed elastohydrodynamic lubrication is tested for validation. The asperity contact and sinusoidal wavy surface are examined by the proposed discrete scheme. Results show the precipitous decline in the boundary of the contact area. The relative error suggests that the pressure distribution is reliable and reflects the accuracy and effectiveness of the developed method.

关键词: mixed lubrication     discretization formula     relative error     Reynolds equation     asperity    

标题 作者 时间 类型 操作

Simulation of cross-flow-induced vibration of tube bundle by surface vorticity method

WANG Fenghao, JIANG Gedong, Lin John Zhang

期刊论文

China ADS sub-critical experimental assembly—Venus-1 and preliminary experiment

SHI Yongqian, XIA Pu, LUO Zhanglin, ZHAO Zhixiang, DING Dazhao, ZHU Qinfu, XIA Haihong, LI Jigen, ZHANG Wei, CAO Jian, QUAN Yanhui, LUO Huangda, WU Xiaofei

期刊论文

An investigation into the heat transfer characteristics of spiral wall with internal rib in a supercritical sliding-pressure operation once-through boiler

TANG Renhu, YIN Fei, WANG Haijun, CHEN Tingkuan

期刊论文

The summary of researches on ADS in China

XIA Haihong, ZHAO Zhixiang, LI Jigen, SHI Yongqian, HAN Yinlu, ZHU Shengyun, XU Yongli, GUAN Xialing, CUI Baoqun, FU Shinian

期刊论文

Greenhouse gas emissions from different pig manure management techniques: a critical analysis

Conor Dennehy, Peadar G. Lawlor, Yan Jiang, Gillian E. Gardiner, Sihuang Xie, Long D Nghiem, Xinmin Zhan

期刊论文

Numerical simulation of fluid dynamics in the stirred tank by the SSG Reynolds Stress Model

Nana QI, Hui WANG, Kai ZHANG, Hu ZHANG

期刊论文

Convective heat transfer in helical coils for constant-property and variable-property flows with high Reynolds

Yufei MAO, Liejin GUO, Bofeng BAI, Ximin ZHANG

期刊论文

Biodiesel production from waste frying oil in sub- and supercritical methanol on a zeolite Y solid acid

Jorge MEDINA-VALTIERRA, Jorge RAMIREZ-ORTIZ

期刊论文

Microbial biodegradation of plastics: Challenges, opportunities, and a critical perspective

期刊论文

Numerical analysis of aerodynamic noise radiated from cross flow fan

CHEN Anbang, LI Song, HUANG Dongtao

期刊论文

Machine learning in building energy management: A critical review and future directions

期刊论文

通过一个等价雷诺数揭示层流到湍流的转捩区域

陈晓东

期刊论文

Reducing environmental impacts through socioeconomic transitions: critical review and prospects

期刊论文

Advances in airborne microorganisms detection using biosensors: A critical review

期刊论文

Iteration framework for solving mixed lubrication computation problems

期刊论文