As resource scarcity, extreme climate change, and pollution levels increase, economic growth must rely on more environmentally friendly and efficient production processes, Fuel cells are an ideal alternative to intern...As resource scarcity, extreme climate change, and pollution levels increase, economic growth must rely on more environmentally friendly and efficient production processes, Fuel cells are an ideal alternative to internal combustion （IC） engines and boilers on the path to greener industries because of their high effi- ciency and environmentally friendly operation, However, as a new energy technology, significant market penetration of fuel cells has not yet been achieved, In this paper, we perform a techno-economic and environmental analysis of fuel cell systems using life cycle and value chain activities, First, we investigate the procedure of fuel cell development and identify what activities should he undertaken according to fuel cell life cycle activities, value chain activities, and end-user acceptance criteria, Next, we present a unified learning of the institutional barriers in fuel cell commercialization, The primary end-user accep- tance criteria are function, cost, and reliability; a fuel cell should outperform these criteria compared with its competitors, such as IC engines and batteries, to achieve a competitive advantage, The repair and maintenance costs of fuel cells （due to low reliability） can lead to a substantial cost increase and decrease in availability, which are the major factors for end-user acceptance, The fuel cell industry must face the challenge of how to overcome this reliability barrier, This paper provides a deeper insight into our work over the years on the main barriers to fuel cell commercialization, and discusses the potential pivotal role of fuel cells in a future low-carbon green economy, It also identifies the needs and points out some direc- tions for this future low-carbon economy, Green energy, supplied with fuel cells, is truly the business mode of the future, Striving for a more sustainable development of economic growth by adopting green public investments and implementing policy initiatives encourages environmentally responsible indus- trial investments.展开更多
In this research,two novel folded lattice-core sandwich cylinders were designed,manufactured,and tested.The lattice core has periodic zigzag corrugations,whose ridges and valleys are directed axially or circumferentia...In this research,two novel folded lattice-core sandwich cylinders were designed,manufactured,and tested.The lattice core has periodic zigzag corrugations,whose ridges and valleys are directed axially or circumferentially.Free vibration and axial compression experiments were performed to reveal the fundamental frequency,free vibration modes,bearing capacity,and failure mode of the cylinder.A folded lattice core effectively restricts local buckling by reducing the dimension of the local skin periodic cell,and improves the global buckling resistance by enhancing the shear stiffness of the sandwich core.The cylinders fail at the mode of material failure and possess excellent load-carrying capacity.An axially directed folded sandwich cylinder has greater load-carrying capacity,while a circumferentially directed folded sandwich cylinder has higher fundamental frequencies.These two types of folded lattices provide a selection for engineers when designing a sandwich cylinder requiring strength or vibration.This research also presents a feasible way to fabricate a large-dimensional folded structure and promote its engineering application.展开更多
This paper reports the anti-blast performance of shallow-buried prefabricated modular tunnel reinforced by basalt fiber-reinforced polymer(BFRP)-steel bars.Three concrete arch members with steel bars and three concret...This paper reports the anti-blast performance of shallow-buried prefabricated modular tunnel reinforced by basalt fiber-reinforced polymer(BFRP)-steel bars.Three concrete arch members with steel bars and three concrete arch members with BFRP-steel bars were fabricated,with the other arch parameters kept constant.The three identical arches were assembled into an integral structure and then buried in soil for field anti-blast experiments.Through the experiment,the pressure on the vault,the displacement and acceleration of the vault,the strain in the reinforcement bars and the macroscopic damage of the arches under the blast load were determined.To evaluate the damage of the arch tunnel,a residual load-bearing capacity test was conducted on the arch members after the explosion experiment.The experimental results showed that the BFRP-steel bars reinforced concrete arch exhibited a higher load-bearing capacity and more safety redundancy than the steel bars reinforced concrete arch,and that the BFRP-steel bars could inhibit the occurrence of concrete cracks to a certain extent.A comparison between the arches assembled at different positions showed that the prefabricated modular tun-nel can be simplified directly as a two-dimensional arch structure under the blast load for analysis and calculation.展开更多
Lattice structures are widely used in many engineering fields due to their excellent mechanical properties such as high specific strength and high specific energy absorption(SEA)capacity.In this paper,square-cell latt...Lattice structures are widely used in many engineering fields due to their excellent mechanical properties such as high specific strength and high specific energy absorption(SEA)capacity.In this paper,square-cell lattice structures with different lattice orientations are investigated in terms of the deformation modes and the energy absorption(EA)performance.Finite element(FE)simulations of in-plane compression are carried out,and the theoretical models from the energy balance principle are developed for calculating the EA of these lattice structures.Satisfactory agreement is achieved between the FE simulation results and the theoretical results.It indicates that the 30◦oriented lattice has the largest EA capacity.Furthermore,inspired by the polycrystal microstructure of metals,novel structures of bi-crystal lattices and quad-crystal lattices are developed through combining multiple singly oriented lattices together.The results of FE simulations of compression indicate that the EA performances of symmetric lattice bi-crystals and quad-crystals are better than those of the identical lattice polycrystal counterparts.This work confirms the feasibility of designing superior energy absorbers with architected meso-structures from the inspiration of metallurgical concepts and microstructures.展开更多
Fractal tubular structures(FTSs)can greatly increase the anti-crushing and energy absorption capacity of the material.To reveal this mechanism,fractal hexagonal tubes(FHTs)with self-similar fractal structure were desi...Fractal tubular structures(FTSs)can greatly increase the anti-crushing and energy absorption capacity of the material.To reveal this mechanism,fractal hexagonal tubes(FHTs)with self-similar fractal structure were designed and prepared.Compression experiments were carried out to verify the crushing modes of structures with different scale factors.Compared with the single-cell structure,FHTs have much greater mean crushing force(MCF).According to the experiments and the numerical simulations,when the side length of the second-order hexagon is 0.3 times of the length of the first-order primary hexagon,the FTS has the greatest peak force(PF)and MCF as well as the most excellent energy-absorbing ability.Three folding styles were revealed by the experiments and the numerical simulation when changing the scale factor,including the overall folding mode,the local foaling mode and the hybrid folding mode.Theoretical plastic models were built,which consistently predicted the MCF.展开更多
The woven textile sandwich composite（WTSC） is a promising lightweight composite.In bending,two competing core shearing failure modes reduce the strength;deflection induced by the core shearing deformation reduces th...The woven textile sandwich composite（WTSC） is a promising lightweight composite.In bending,two competing core shearing failure modes reduce the strength;deflection induced by the core shearing deformation reduces the flexural rigidity.To replace a solid composite laminate,the span of WTSC panel must be greater than a critical value,which was deduced on the condition that the load capacity and flexural rigidity of the WTSC panel are equal to those of the composite laminate.Three WTSC panels were tested in bending,so that the failure modes were observed,and the critical spans were determined.Using the alternative design method,the WTSC based wind deflector with reduced weight has been fabricated and mounted on the CRH（China Railway High-speed）.展开更多
Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical appr...Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical approaches.The metastructure is composed of periodic rubber layers and concrete layers embedded with three-dimensional resonators,which can be freely designed with multi local resonant frequencies to attenuate vibrations at required frequencies and widen the attenuation bandgap.The metastructure can also effectively attenuate seismic responses.Compared with layered rubber-based structures,the metastructure has more excellent wave attenuation effects with greater attenuation and wider bandgap.展开更多
In this study,various nonionic surfactants(NS) with different ethylene oxide(EO) numbers and tail lengths and its binary blends with anionic surfactants(AS) were used as emulsifiers for naphthenic oil to form the micr...In this study,various nonionic surfactants(NS) with different ethylene oxide(EO) numbers and tail lengths and its binary blends with anionic surfactants(AS) were used as emulsifiers for naphthenic oil to form the microemulsion metalworking fluids(MWFs),and the effects of them on the stability of the emulsion system were investigated by formulation triangle method.The results indicated that binary complex surfactants of NS and AS as emulsifiers exhibited better emulsifying effect than that of single NS.NS with different EO numbers and tail lengths presented various emulsifying effects.NS(EO=10)exhibited the greatest number of stable formulations,especially the TX-10,but no linear relationship existed between the number of stable formulations and the tail length of NS.In addition,aromatic primary alcohol ethoxy late(APAE) series surfactants containing benzene groups similar to the cycloalkanes in the naphthenic oil so that presented the best emulsifying affect and the greatest number of stable formulations.The co-surfactant of sodium dodecyl benzene sulfonate(SDBS) binary blends with NS exerted the best synergistic effect,and the stable formulations numbers were ranged from 5 to 7,next sodium stearate(SS) comes last followed by sodium dodecyl sulfate(SDS-1) and sodium dodecyl sulfonate(SDS-2).展开更多
为了解鄂西北地区猪场猪圆环病毒2型(Porcine circovirus type 2,PCV-2)不同免疫水平下的流行病学特点,试验采用ELISA法和PCR法分别对2017—2019年鄂西北地区猪场送检的1 456份血样和134份临床疑似PCV-2感染的病料进行了PCV-2抗体和病...为了解鄂西北地区猪场猪圆环病毒2型(Porcine circovirus type 2,PCV-2)不同免疫水平下的流行病学特点,试验采用ELISA法和PCR法分别对2017—2019年鄂西北地区猪场送检的1 456份血样和134份临床疑似PCV-2感染的病料进行了PCV-2抗体和病原检测,并统计采样猪的PCV-2疫苗免疫情况。根据2017—2019年采样猪PCV-2疫苗免疫记录,分别统计不同年份PCV-2疫苗免疫密度,分析不同免疫密度下PCV-2抗体水平差异。再根据采样猪的PCV-2疫苗免疫记录将猪分为未免疫、1次免疫及≥2次免疫共3个不同免疫频次组,分析不同免疫频次下PCV-2抗体阳性率和PCV-2病原阳性率差异。结果表明:2017年、2018年和2019年PCV-2疫苗免疫密度分别为91.2%、49.3%和39.9%,PCV-2抗体阳性率分别为78.1%、39.1%和34.8%,PCV-2疫苗免疫密度下降导致PCV-2抗体阳性率显著下降(P<0.05);未免疫、1次免疫和≥2次免疫的PCV-2抗体阳性率分别为32.4%、66.0%和86.5%,PCV-2病原阳性率分别为73.7%、42.0%和18.5%,PCV-2疫苗免疫频次增加能显著提高PCV-2抗体阳性率(P<0.05),显著降低PCV-2病原阳性率(P<0.05)。说明鄂西北地区PCV-2防控形势严峻,增加免疫密度和加强免疫频次可提高PCV-2抗体水平,降低猪只感染PCV-2病原的风险。展开更多
基金the Ministry of Economic Development and Trade of Government of Alberta for the Campus Alberta Innovation Program (CAIP) Research Chair (RCP-12-001BCAIP)
文摘As resource scarcity, extreme climate change, and pollution levels increase, economic growth must rely on more environmentally friendly and efficient production processes, Fuel cells are an ideal alternative to internal combustion （IC） engines and boilers on the path to greener industries because of their high effi- ciency and environmentally friendly operation, However, as a new energy technology, significant market penetration of fuel cells has not yet been achieved, In this paper, we perform a techno-economic and environmental analysis of fuel cell systems using life cycle and value chain activities, First, we investigate the procedure of fuel cell development and identify what activities should he undertaken according to fuel cell life cycle activities, value chain activities, and end-user acceptance criteria, Next, we present a unified learning of the institutional barriers in fuel cell commercialization, The primary end-user accep- tance criteria are function, cost, and reliability; a fuel cell should outperform these criteria compared with its competitors, such as IC engines and batteries, to achieve a competitive advantage, The repair and maintenance costs of fuel cells （due to low reliability） can lead to a substantial cost increase and decrease in availability, which are the major factors for end-user acceptance, The fuel cell industry must face the challenge of how to overcome this reliability barrier, This paper provides a deeper insight into our work over the years on the main barriers to fuel cell commercialization, and discusses the potential pivotal role of fuel cells in a future low-carbon green economy, It also identifies the needs and points out some direc- tions for this future low-carbon economy, Green energy, supplied with fuel cells, is truly the business mode of the future, Striving for a more sustainable development of economic growth by adopting green public investments and implementing policy initiatives encourages environmentally responsible indus- trial investments.
基金Support from the National Natural Science Foundation of China(11672130 and 11972184)the State Key Laboratory of Mechanics and Control of Mechanical Structures(MCMS-0217G03)Aerospace System Engineering Shanghai are gratefully acknowledged.
文摘In this research,two novel folded lattice-core sandwich cylinders were designed,manufactured,and tested.The lattice core has periodic zigzag corrugations,whose ridges and valleys are directed axially or circumferentially.Free vibration and axial compression experiments were performed to reveal the fundamental frequency,free vibration modes,bearing capacity,and failure mode of the cylinder.A folded lattice core effectively restricts local buckling by reducing the dimension of the local skin periodic cell,and improves the global buckling resistance by enhancing the shear stiffness of the sandwich core.The cylinders fail at the mode of material failure and possess excellent load-carrying capacity.An axially directed folded sandwich cylinder has greater load-carrying capacity,while a circumferentially directed folded sandwich cylinder has higher fundamental frequencies.These two types of folded lattices provide a selection for engineers when designing a sandwich cylinder requiring strength or vibration.This research also presents a feasible way to fabricate a large-dimensional folded structure and promote its engineering application.
基金Supports from the Natural Science Foundations of Jiangsu Province(Grant No.BK20190573)General Project of Social Development in Jiangsu Province(Grant No.BE2020716)the National Natural Science Foundation of China(Grant No.51778622).
文摘This paper reports the anti-blast performance of shallow-buried prefabricated modular tunnel reinforced by basalt fiber-reinforced polymer(BFRP)-steel bars.Three concrete arch members with steel bars and three concrete arch members with BFRP-steel bars were fabricated,with the other arch parameters kept constant.The three identical arches were assembled into an integral structure and then buried in soil for field anti-blast experiments.Through the experiment,the pressure on the vault,the displacement and acceleration of the vault,the strain in the reinforcement bars and the macroscopic damage of the arches under the blast load were determined.To evaluate the damage of the arch tunnel,a residual load-bearing capacity test was conducted on the arch members after the explosion experiment.The experimental results showed that the BFRP-steel bars reinforced concrete arch exhibited a higher load-bearing capacity and more safety redundancy than the steel bars reinforced concrete arch,and that the BFRP-steel bars could inhibit the occurrence of concrete cracks to a certain extent.A comparison between the arches assembled at different positions showed that the prefabricated modular tun-nel can be simplified directly as a two-dimensional arch structure under the blast load for analysis and calculation.
基金Project supported by the National Natural Science Foundation of China(No.11772231)。
文摘Lattice structures are widely used in many engineering fields due to their excellent mechanical properties such as high specific strength and high specific energy absorption(SEA)capacity.In this paper,square-cell lattice structures with different lattice orientations are investigated in terms of the deformation modes and the energy absorption(EA)performance.Finite element(FE)simulations of in-plane compression are carried out,and the theoretical models from the energy balance principle are developed for calculating the EA of these lattice structures.Satisfactory agreement is achieved between the FE simulation results and the theoretical results.It indicates that the 30◦oriented lattice has the largest EA capacity.Furthermore,inspired by the polycrystal microstructure of metals,novel structures of bi-crystal lattices and quad-crystal lattices are developed through combining multiple singly oriented lattices together.The results of FE simulations of compression indicate that the EA performances of symmetric lattice bi-crystals and quad-crystals are better than those of the identical lattice polycrystal counterparts.This work confirms the feasibility of designing superior energy absorbers with architected meso-structures from the inspiration of metallurgical concepts and microstructures.
基金Supports from the National Natural Science Foundation of China(11671230)the State Key Laboratory of Mechanics and Control of Mechanical Structures(MCMS-0217G03)are gratefully acknowledged.
文摘Fractal tubular structures(FTSs)can greatly increase the anti-crushing and energy absorption capacity of the material.To reveal this mechanism,fractal hexagonal tubes(FHTs)with self-similar fractal structure were designed and prepared.Compression experiments were carried out to verify the crushing modes of structures with different scale factors.Compared with the single-cell structure,FHTs have much greater mean crushing force(MCF).According to the experiments and the numerical simulations,when the side length of the second-order hexagon is 0.3 times of the length of the first-order primary hexagon,the FTS has the greatest peak force(PF)and MCF as well as the most excellent energy-absorbing ability.Three folding styles were revealed by the experiments and the numerical simulation when changing the scale factor,including the overall folding mode,the local foaling mode and the hybrid folding mode.Theoretical plastic models were built,which consistently predicted the MCF.
基金Project supported by the National Natural Science Foundation of China(Nos.11172089 and 11372095)the State Key Laboratory of Mechanics and Control of Mechanical Structures(Nos.MCMS-0212G01 and MCMS-0215G01)
文摘The woven textile sandwich composite（WTSC） is a promising lightweight composite.In bending,two competing core shearing failure modes reduce the strength;deflection induced by the core shearing deformation reduces the flexural rigidity.To replace a solid composite laminate,the span of WTSC panel must be greater than a critical value,which was deduced on the condition that the load capacity and flexural rigidity of the WTSC panel are equal to those of the composite laminate.Three WTSC panels were tested in bending,so that the failure modes were observed,and the critical spans were determined.Using the alternative design method,the WTSC based wind deflector with reduced weight has been fabricated and mounted on the CRH（China Railway High-speed）.
基金Supports from National Natural Science Foundation of China(Grant Nos.U20A20286 and 11972184)the Systematic Project of Guangxi Key Laboratory of Disaster Prevention and Engineering Safety(Grant No.2021ZDK006)+1 种基金Natural Science Foundation of Jiangsu Province of China(Grant No.BK20201286)Science and Technology Project of Jiangsu Province of China(Grant No.BE2020716)are gratefully acknowledged.
文摘Combining periodic layered structure with three-dimensional cylindrical local resonators,a hybrid metastructure with improved wave isolation ability was designed and investigated through theoretical and numerical approaches.The metastructure is composed of periodic rubber layers and concrete layers embedded with three-dimensional resonators,which can be freely designed with multi local resonant frequencies to attenuate vibrations at required frequencies and widen the attenuation bandgap.The metastructure can also effectively attenuate seismic responses.Compared with layered rubber-based structures,the metastructure has more excellent wave attenuation effects with greater attenuation and wider bandgap.
基金supported from the Shanghai Association for Science and Technology Achievements Transformation Alliance Program(No.LM201851)the National Natural Science Foundation of China(Nos.21878188,21606151 and 21707092)+2 种基金Shanghai Excellent Technology Leaders Program(No.17XD1424900)"Chenguang Program"from Shanghai Education Development FoundationShanghai Municipal Education Commission(No.18CGB12)。
文摘In this study,various nonionic surfactants(NS) with different ethylene oxide(EO) numbers and tail lengths and its binary blends with anionic surfactants(AS) were used as emulsifiers for naphthenic oil to form the microemulsion metalworking fluids(MWFs),and the effects of them on the stability of the emulsion system were investigated by formulation triangle method.The results indicated that binary complex surfactants of NS and AS as emulsifiers exhibited better emulsifying effect than that of single NS.NS with different EO numbers and tail lengths presented various emulsifying effects.NS(EO=10)exhibited the greatest number of stable formulations,especially the TX-10,but no linear relationship existed between the number of stable formulations and the tail length of NS.In addition,aromatic primary alcohol ethoxy late(APAE) series surfactants containing benzene groups similar to the cycloalkanes in the naphthenic oil so that presented the best emulsifying affect and the greatest number of stable formulations.The co-surfactant of sodium dodecyl benzene sulfonate(SDBS) binary blends with NS exerted the best synergistic effect,and the stable formulations numbers were ranged from 5 to 7,next sodium stearate(SS) comes last followed by sodium dodecyl sulfate(SDS-1) and sodium dodecyl sulfonate(SDS-2).
文摘为了解鄂西北地区猪场猪圆环病毒2型(Porcine circovirus type 2,PCV-2)不同免疫水平下的流行病学特点,试验采用ELISA法和PCR法分别对2017—2019年鄂西北地区猪场送检的1 456份血样和134份临床疑似PCV-2感染的病料进行了PCV-2抗体和病原检测,并统计采样猪的PCV-2疫苗免疫情况。根据2017—2019年采样猪PCV-2疫苗免疫记录,分别统计不同年份PCV-2疫苗免疫密度,分析不同免疫密度下PCV-2抗体水平差异。再根据采样猪的PCV-2疫苗免疫记录将猪分为未免疫、1次免疫及≥2次免疫共3个不同免疫频次组,分析不同免疫频次下PCV-2抗体阳性率和PCV-2病原阳性率差异。结果表明:2017年、2018年和2019年PCV-2疫苗免疫密度分别为91.2%、49.3%和39.9%,PCV-2抗体阳性率分别为78.1%、39.1%和34.8%,PCV-2疫苗免疫密度下降导致PCV-2抗体阳性率显著下降(P<0.05);未免疫、1次免疫和≥2次免疫的PCV-2抗体阳性率分别为32.4%、66.0%和86.5%,PCV-2病原阳性率分别为73.7%、42.0%和18.5%,PCV-2疫苗免疫频次增加能显著提高PCV-2抗体阳性率(P<0.05),显著降低PCV-2病原阳性率(P<0.05)。说明鄂西北地区PCV-2防控形势严峻,增加免疫密度和加强免疫频次可提高PCV-2抗体水平,降低猪只感染PCV-2病原的风险。
