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Ductile extension of 3-D external circumferential cracks in pipe structures

Wuchao YANG, Xudong QIAN

Frontiers of Structural and Civil Engineering 2011, Volume 5, Issue 3,   Pages 294-303 doi: 10.1007/s11709-011-0115-9

Abstract: This study investigates the ductile fracture resistance of 3-D external circumferential cracks in the wall of a steel pipe under remote tension, using a damage-mechanism model originally proposed by Gurson and Tvergaard. The ductile crack extension utilizes an element extinction technique implemented in the computational cell framework. The key parameter for the computational cell method, i.e., the initial porosity ratio , is calibrated using both the fracture resistance and the load-deformation responses obtained from fracture tests of multiple single-edge bend [SE(B)] specimens made of high-strength steel, HY80, which has a yield strength of 630 MPa. The fracture resistance along the 3-D semi-elliptical crack front is computed from the calibrated cell model. Based on the similarity concept in the near-tip stress-strain fields, this study demonstrates that an equivalent 2-D axi-symmetric model provides conservative estimations of the fracture resistance for 3-D circumferential cracks in pipes.

Keywords： ductile fracture     computational cell method     G-T model     J-R curve    

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Detection of void and metallic inclusion in 2D piezoelectric cantilever beam using impedance measurements

NANTHAKUMAR, R. K. ANNABATTULA, X. ZHUANG

Frontiers of Structural and Civil Engineering 2019, Volume 13, Issue 3,   Pages 542-556 doi: 10.1007/s11709-018-0496-0

Abstract: current work is to improve the existing inverse methodology of void-detection based on a target impedance curveIn this work, mode-shape dependent shifting phenomenon of peaks of impedance curve with change in voiditeration starting from each initial guess, the difference between the computationally obtained impedance curveand the target impedance curve has been reduced.

Keywords： piezoelectricity     impedance curve     mode shapes     inverse problem     flaw detection     curve shifting    

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Availability of wind energy resource potential for power generation at Jos, Nigeria

Ajayi, R. O. Fagbenle, J. Katende, J. O. Okeniyi

Frontiers in Energy 2011, Volume 5, Issue 4,   Pages 376-385 doi: 10.1007/s11708-011-0167-5

Abstract: The objective of this study was to assess the potential viability of the wind resource potential in Jos, Plateau state, Nigeria for power generation. The monthly mean wind speeds that span from 1987 to 2007 were employed to statistically analyze the monthly, annual and seasonal potentials of the wind energy resources at the site. Besides, the results were employed together with two models of wind energy conversion system to simulate the likely average output power. The outcome showed that Jos was suitable as a site for wind farm projects of varying sizes and that MW·h to GW·h of electricity is likely to be produced per period of months, seasons and years. The average wind speed range at the site was also estimated to be between 6.7 and 11.8 m/s across the months, years and seasons.

Keywords： green electricity     renewable resources     Weibull statistics     Jos     Nigeria    

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Modeling of alkali-silica reaction in concrete: a review

J.W. PAN, Y.T. FENG, J.T. WANG, Q.C. SUN, C.H. ZHANG, D.R.J. OWEN

Frontiers of Structural and Civil Engineering 2012, Volume 6, Issue 1,   Pages 1-18 doi: 10.1007/s11709-012-0141-2

Abstract: This paper presents a comprehensive review of modeling of alkali-silica reaction (ASR) in concrete. Such modeling is essential for investigating the chemical expansion mechanism and the subsequent influence on the mechanical aspects of the material. The concept of ASR and the mechanism of expansion are first outlined, and the state-of-the-art of modeling for ASR, the focus of the paper, is then presented in detail. The modeling includes theoretical approaches, meso- and macroscopic models for ASR analysis. The theoretical approaches dealt with the chemical reaction mechanism and were used for predicting pessimum size of aggregate. Mesoscopic models have attempted to explain the mechanism of mechanical deterioration of ASR-affected concrete at material scale. The macroscopic models, chemo-mechanical coupling models, have been generally developed by combining the chemical reaction kinetics with linear or nonlinear mechanical constitutive, and were applied to reproduce and predict the long-term behavior of structures suffering from ASR. Finally, a conclusion and discussion of the modeling are given.

Keywords： alkali-silica reaction (ASR)     modeling     concrete     mesoscopic     macroscopic    

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Carbon dioxide: a renewable feedstock for the synthesis of fine and bulk chemicals

PATIL, Pawan J. TAMBADE, Sachin R. JAGTAP, Bhalchandra M. BHANAGE,

Frontiers of Chemical Science and Engineering 2010, Volume 4, Issue 2,   Pages 213-235 doi: 10.1007/s11705-009-0227-0

Abstract: The syntheses of carbon dioxide (CO) based industrially important chemicals have gained considerable interest in view of the sustainable chemistry and “green chemistry” concepts. In this review, recent developments in the chemical fixation of CO to valuable chemicals are discussed. The synthesis of five-member cyclic carbonates , cycloaddition of CO to epoxides is one of the promising reactions replacing the existing poisonous phosgene-based synthetic route. This review focuses on the synthesis of cyclic carbonates, vinyl carbamates, and quinazoline-2,4(1,3)-diones reaction of CO and epoxide, amines/phenyl acetylene, 2-aminobenzinitrile and other chemicals. Direct synthesis of dimethyl carbonate, 1,3-disubstituted urea and 2-oxazolidinones/2-imidazolidinones have limitations at present because of the reaction equilibrium and chemical inertness of CO. The preferred alternatives for their synthesis like transesterification of ethylene carbonate with methanol, transamination of ethylene carbonate with primary amine and transamination reaction of ethylene carbonate with diamines/-aminoalcohols are discussed. These methodologies offer marked improvements for greener chemical fixation of CO in to industrially important chemicals.

Keywords： inertness     CO     phosgene-based synthetic     quinazoline-2     4     equilibrium    

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Coupling the porous conditional moment closure with the random pore model: applications to gasification and CO

R. CHODANKA, M. J. CLEARY, A. Y. KLIMENKO

Frontiers of Chemical Science and Engineering 2012, Volume 6, Issue 1,   Pages 84-93 doi: 10.1007/s11705-011-1164-2

Abstract: Gasification of coal or biomass with in situ CO capture simultaneously allows production of clean hydrogen at relatively low cost and reduced emission of CO into the atmosphere. Clearly, this technology has a great potential for a future carbon constrained economy. Therefore, the development of a comprehensive, physically-based gasifier model is important. The sub-models that describe reactive transport processes in coal particles as well as in particles of CO sorbent material are among the key sub-models, which provide a necessary input for an overall gasifier model. Both coal and sorbent are materials that have complicated pore structures. The porous conditional moment closure (PCMC) model proves to be adequate for modeling reactive transport through porous media with fixed pore structure. Consumption of coal in the heterogeneous gasification reaction, however, widens the pores and reduces the surface area available for this reaction. At the same time, formation of a carbonate layer narrows the pores in the sorbent material and reduces the reaction rate of CO sorption. In both cases the pore structures are affected. Such changes are not taken into account in the existing PCMC model. In this study, we obtain the parameters of the diffusive tracer distribution based on the pore size distribution given by the widely applied random pore model (RPM), while coupling PCMC with RPM. Such coupling allows taking into account changes in pore structure caused by heterogeneous reactions and thus improves the accuracy of these key sub-models.

Keywords： gasification     CO2 capture     PCMC     RPM    

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Correlation between tension softening relation and crack extension resistance in concrete

Xiufang ZHANG , Shilang XU ,

Frontiers of Structural and Civil Engineering 2009, Volume 3, Issue 3,   Pages 323-329 doi: 10.1007/s11709-009-0041-2

Abstract: fracture energy consumption with crack propagation can be described by a crack extension resistance curvebehavior in concrete was used to develop a new fracture criterion, the crack extension resistance curveThe crack extension resistance is then a function of the softening curve, which is a basic mechanicalThe relationship between the softening curve and the crack extension resistance curve is then analyzedrelated to the characteristic point on used tension softening curve.

Keywords： concrete     fracture process zone     crack extension GR resistance     tension softening curve    

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Thermal Management of Vehicle Cabins, External Surfaces, and Onboard Electronics: An Overview Review

Garrett J. Marshall, Colin P. Mahony, Matthew J. Rhodes, Steve R.

Engineering 2019, Volume 5, Issue 5,   Pages 954-969 doi: 10.1016/j.eng.2019.02.009

Abstract:

Reducing heat accumulation within vehicles and ensuring appropriate vehicular temperature levels can lead to enhanced
vehicle fuel economy, range, reliability, longevity, passenger comfort, and safety. Advancements in vehicle thermal management remain key as new technologies, consumer demand, societal concerns, and government regulations emerge and evolve. This study summarizes several recent advances in vehicle thermal management technology and modeling, with a focus on three key areas: the cabin, electronics, and exterior components of vehicles. Cabin-related topics covered include methods for reducing thermal loads and improving heating, ventilation, and air-conditioning (HVAC) systems; and advancements in window glazing/tinting and vehicle surface treatments. For the thermal management of electronics, including batteries and insulated-gate bipolar transistors (IGBTs), active and passive cooling methods that employ heat pipes, heat sinks, jet impingement, forced convection, and phase-change materials are discussed. Finally, efforts to model and enhance the heat transfer of exterior vehicular components are reviewed while considering drag/friction forces and environmental effects. Despite advances in the field of vehicle thermal management, challenges still exist; this article provides a broad summary of the major issues, with recommendations for further study.

Keywords： Vehicle design     Automotive engineering     Electronics packaging     Heat pipes     Climate control     Heating ventilation and air-conditioning     Battery cooling     Thermal soak    

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Seismic performance of composite moment-resisting frames achieved with sustainable CFST members

MACEDO,J. M. CASTRO,R. MONTEIRO,N. SILVESTRE

Frontiers of Structural and Civil Engineering 2016, Volume 10, Issue 3,   Pages 312-332 doi: 10.1007/s11709-016-0345-y

Abstract: The main objective of the research presented in this paper is to study the bending behaviour of Concrete Filled Steel Tube (CFST) columns made with Rubberized Concrete (RuC), and to assess the seismic performance of moment-resisting frames with these structural members. The paper describes an experimental campaign where a total of 36 specimens were tested, resorting to a novel testing setup, aimed at reducing both the preparation time and cost of the test specimens. Different geometrical and material parameters were considered, namely cross-section type, cross-section slenderness, aggregate replacement ratio, axial load level and lateral loading type. The members were tested under both monotonic and cyclic lateral loading, with different levels of applied axial loading. The test results show that the bending behaviour of CFST elements is highly dependent on the steel tube properties and that the type of infill does not have a significant influence on the flexural behaviour of the member. It is also found that Eurocode 4 is conservative in predicting the flexural capacity of the tested specimens. Additionally, it was found that the seismic design of composite moment-resisting frames with CFST columns, according to Eurocode 8, not only leads to lighter design solutions but also to enhanced seismic performance in comparison to steel frames.

Keywords： concrete filled steel tubes     rubberized concrete     composite frames     seismic performance assessment    

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Is there an inverted U-shaped curve?Empirical analysis of the Environmental Kuznets Curve in agrochemicals

Fei LI,Suocheng DONG,Fujia LI,Libiao YANG

Frontiers of Environmental Science & Engineering 2016, Volume 10, Issue 2,   Pages 276-287 doi: 10.1007/s11783-014-0700-y

Abstract: cointegration, and panel-based dynamic ordinary least squares to investigate the Environmental Kuznets CurveThis relationship takes on the inverted U-shaped Environmental Kuznets Curve, and the value of the turning

Keywords： Environmental Kuznets Curve     agrochemical     China    

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Erratum to: On secondary new particle formation in China

Markku KULMAMA,Tuukka Petäjä,Veli-Matti KERMINEN,Joni KUJANSUU,Taina RUUSKANEN,Aijun DING,Wei NIE,MinHU,Zhibin WANG,Zhijun WU,Lin WANG,Douglas R.

Frontiers of Environmental Science & Engineering 2016, Volume 10, Issue 5, doi: 10.1007/s11783-016-0857-7

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A Floating Island Treatment System for the Removal of Phosphorus from Surface Waters Article

Brown,Treavor Boyer,R.J. Sindelar,Sam Arden,Amar Persaud,Sherry Brandt-Williams

Engineering 2018, Volume 4, Issue 5,   Pages 597-609 doi: 10.1016/j.eng.2018.08.002

Abstract: and orthophosphate (\(\rm PO_4^{3-}\) Keywords： Phosphorus removal     Lake ecosystem     Floating island treatment    

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On secondary new particle formation in China

Markku Kulmala,Tuukka Petäjä,Veli-Matti Kerminen,Joni Kujansuu,Taina Ruuskanen,Aijun Ding,Wei Nie,MinHu,Zhibin Wang,Zhijun Wu,Lin Wang,Douglas R.

Frontiers of Environmental Science & Engineering 2016, Volume 10, Issue 5, doi: 10.1007/s11783-016-0850-1

Abstract: Formation of new atmospheric aerosol particles is a global phenomenon that has been observed to take place in even heavily-polluted environments. In China, new particle production has been observed at very high pollution levels (condensation sink about 0.1s ) in several megacities. A holistic scientific understanding on the atmospheric phenomena associated with air quality as a whole, as well as on the connection between air quality and climate, is lacking at the moment.With a network of observation stations, we will be able to understand the interactions and feedbacks associated with the urban pollution mixture, and ultimately, are ready to make targeted strategies for the pollution control. This paper summaries the recent advances in studying secondary new aerosol formation in China and shows how increased process-level understanding will help us to understand air quality-climate-weather interactions and how the feedbacks and interactions affect the air quality in highly-polluted environments such as those frequently encountered in Chinese megacities. Formation of new atmospheric aerosol particles is a global phenomenon that has been observed to take place in even heavily-polluted environments. However, in all environments there appears to be a threshold value of the condensation sink (due to pre-existing aerosol particles) after which the formation rate of 3 nm particles is no longer detected. In China, new particle production has been observed at very high pollution levels (condensation sink about 0.1 s ) in several megacities, including Beijing, Shanghai and Nanjing as well as in Pearl River Delta (PRD). Here we summarize the recent findings obtained from these studies and discuss the various implications these findings will have on future research and policy.

Keywords： Aerosol particles     Heavily-polluted environments     Condensation sink     New particle production     Megacities    

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Effect of land use and land cover change on soil erosion and the spatio-temporal variation in Liupan Mountain Region, southern Ningxia, China

J. M. R?MKENS, Rui LI, Fang WANG, Jie CHEN

Frontiers of Environmental Science & Engineering 2011, Volume 5, Issue 4,   Pages 564-572 doi: 10.1007/s11783-011-0348-9

Abstract: The Liupan Mountains are located in the southern Ningxia Hui Autonomous Region of China, that forms an important divide between landforms and bio-geographic regions. The populated part of the Liupan Mountain Region has suffered tremendous ecological damage over time due to population pressure, excessive demand and inappropriate use of agricultural land resources. To present the relationship between land use/cover change and spatio-temporal variation of soil erosion, data sets of land use between the late 1980s and 2000 were obtained from Landsat Thematic Mapper (TM) imagery, and spatial models were used to characterize landscape and soil erosion conditions. Also, soil erosion in response to land use and land cover change were quantified and analyzed using data from geographical information systems and remote sensing. Soil erosion by water was the dominant mode of soil loss, while soil erosion by wind was only present on a relatively small area. The degree of soil erosion was classified into five severity classes: slight, light, moderate, severe, and very severe. Soil erosion in the Liupan Mountain Region increased between the late 1980s and 2000, both in terms of acreage and severity. Moderate, severe, and very severe eroded areas accounted for 54.86% of the total land area. The lightly eroded area decreased, while the moderately eroded area increased by 368817 ha (22%) followed by severe erosion with 146552 ha (8.8%), and very severe erosion by 97067.6 ha (5.8%). Soil loss on sloping cropland increased with slope gradients. About 90% of the cropland was located on slopes less than 15°. Most of the increase in soil erosion on cropland was due to conversion of steep slopes to cropland and degradation of grassland and increased activities. Soil erosion was severe on grassland with a moderate or low grass cover and on dry land. Human activities, cultivation on steep slopes, and overgrazing of pastures were the main reasons for the increase in erosion severity.

Keywords： land use/land cover change     soil erosion     geographical information system     remote sensing     Liupan Mountain Region    

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REINTEGRATION OF CROP-LIVESTOCK SYSTEMS IN EUROPE: AN OVERVIEW

J. VAN DE VEN, Davey L. JONES, David R. CHADWICK

Frontiers of Agricultural Science and Engineering 2021, Volume 8, Issue 1,   Pages 111-129 doi: 10.15302/J-FASE-2020373

Abstract: Ongoing specialization of crop and livestock systems provides socioeconomic benefits to the farmer but has led to greater externalization of environmental costs when compared to mixed farming systems. Better integration of crop and livestock systems offers great potential to rebalance the economic and environmental trade-offs in both systems. The aims of this study were to analyze changes in farm structure and review and evaluate the potential for reintegrating specialized intensive crop and livestock systems, with specific emphasis on identifying the co-benefits and barriers to reintegration. Historically, animals were essential to recycle nutrients in the farming system but this became less important with the availability of synthetic fertilisers. Although mixed farm systems can be economically attractive, benefits of scale combined with socio-economic factors have resulted in on-farm and regional specialization with negative environmental impacts. Reintegration is therefore needed to reduce nutrient surpluses at farm, regional and national levels, and to improve soil quality in intensive cropping systems. Reintegration offers practical and cost-effective options to widen crop rotations and promotes the use of organic inputs and associated benefits, reducing dependency on synthetic fertilisers, biocides and manure processing costs. Circular agriculture goes beyond manure management and requires adaptation of both food production and consumption patterns, matching local capacity to produce with food demand. Consequently, feed transport, greenhouse gas emissions, nutrient surpluses and nutrient losses to the environment can be reduced. It is concluded that reintegration of specialized farms within a region can provide benefits to farmers but may also lead to further intensification of land use. New approaches within a food system context offer alternatives for reintegration, but require strong policy incentives which show clear, tangible and lasting benefits for farmers, the environment and the wider community.

Keywords： circular agriculture     coupled farming systems     mixed farming     specialised farming systems     GHG    

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Title Author Date Type Operation

Ductile extension of 3-D external circumferential cracks in pipe structures

Wuchao YANG, Xudong QIAN

Journal Article

Detection of void and metallic inclusion in 2D piezoelectric cantilever beam using impedance measurements

NANTHAKUMAR, R. K. ANNABATTULA, X. ZHUANG

Journal Article

Availability of wind energy resource potential for power generation at Jos, Nigeria

Ajayi, R. O. Fagbenle, J. Katende, J. O. Okeniyi

Journal Article

Modeling of alkali-silica reaction in concrete: a review

J.W. PAN, Y.T. FENG, J.T. WANG, Q.C. SUN, C.H. ZHANG, D.R.J. OWEN

Journal Article

Carbon dioxide: a renewable feedstock for the synthesis of fine and bulk chemicals

PATIL, Pawan J. TAMBADE, Sachin R. JAGTAP, Bhalchandra M. BHANAGE,

Journal Article

Coupling the porous conditional moment closure with the random pore model: applications to gasification and CO

R. CHODANKA, M. J. CLEARY, A. Y. KLIMENKO

Journal Article

Correlation between tension softening relation and crack extension resistance in concrete

Xiufang ZHANG , Shilang XU ,

Journal Article

Thermal Management of Vehicle Cabins, External Surfaces, and Onboard Electronics: An Overview

Garrett J. Marshall, Colin P. Mahony, Matthew J. Rhodes, Steve R.

Journal Article

Seismic performance of composite moment-resisting frames achieved with sustainable CFST members

MACEDO,J. M. CASTRO,R. MONTEIRO,N. SILVESTRE

Journal Article

Is there an inverted U-shaped curve?Empirical analysis of the Environmental Kuznets Curve in agrochemicals

Fei LI,Suocheng DONG,Fujia LI,Libiao YANG

Journal Article

Erratum to: On secondary new particle formation in China

Markku KULMAMA,Tuukka Petäjä,Veli-Matti KERMINEN,Joni KUJANSUU,Taina RUUSKANEN,Aijun DING,Wei NIE,MinHU,Zhibin WANG,Zhijun WU,Lin WANG,Douglas R.

Journal Article

A Floating Island Treatment System for the Removal of Phosphorus from Surface Waters

Brown,Treavor Boyer,R.J. Sindelar,Sam Arden,Amar Persaud,Sherry Brandt-Williams

Journal Article

On secondary new particle formation in China

Markku Kulmala,Tuukka Petäjä,Veli-Matti Kerminen,Joni Kujansuu,Taina Ruuskanen,Aijun Ding,Wei Nie,MinHu,Zhibin Wang,Zhijun Wu,Lin Wang,Douglas R.

Journal Article

Effect of land use and land cover change on soil erosion and the spatio-temporal variation in Liupan Mountain Region, southern Ningxia, China

J. M. R?MKENS, Rui LI, Fang WANG, Jie CHEN

Journal Article

REINTEGRATION OF CROP-LIVESTOCK SYSTEMS IN EUROPE: AN OVERVIEW

J. VAN DE VEN, Davey L. JONES, David R. CHADWICK

Journal Article