The microstructure evolution and strengthening mechanism of WE54 alloy with different hard-plate rolling(HPR)processes were systematically investigated.The results suggest that the mechanical properties of the as-roll...The microstructure evolution and strengthening mechanism of WE54 alloy with different hard-plate rolling(HPR)processes were systematically investigated.The results suggest that the mechanical properties of the as-rolled alloys are significantly enhanced compared to those of the as-cast alloy.When subjected to three rolling passes at 450℃ and 490℃,grain refinement occurs due to dynamic recrystallization.A mixed-grain structure is formed after a single pass rolling with a substantial reduction(65%)at 490℃.The dynamic recrystallization(DRX)mechanism of the alloy during the HPR includes continuous dynamic recrystallization(CDRX),discontinuous dynamic recrystallization(DDRX),and twin-induced recrystallization(TDRX).The WE54 alloy exhibits the highest strength after three passes of HPR at 450℃,with tensile strength and yield strength of 374 and 323 MPa,respectively.The significant improvement in the mechanical properties of the alloy is primarily attributed to fine-grain strengthening,solid solution strengthening,and dislocation strengthening.展开更多
Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformati...Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas,where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy.In this paper,a series of pullout tests were conducted on fiber optic(FO)cables embedded in the frozen soil to investigate the cable‒soil interface behavior.An experimental study was performed on interaction effects,particularly focused on the water content of unfrozen soil,freezing duration,and differential distribution of water content in frozen soil.The highresolution axial strains of FO cables were obtained using a sensing interrogator,and were used to calculate the interface shear stress.The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models.Three freezing periods,correlating with the phase change process between ice and water,were analyzed.The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times.A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information.Additionally,the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements.This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil,which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.展开更多
Interbody fusion is recognized as the golden standard of surgical intervention for degenerative disc disease(DDD).Interbody fusion cage made of polyetheretherketone(PEEK)is commonly used in lumbar interbody fusion sur...Interbody fusion is recognized as the golden standard of surgical intervention for degenerative disc disease(DDD).Interbody fusion cage made of polyetheretherketone(PEEK)is commonly used in lumbar interbody fusion surgery in the treatment of DDD worldwide.However,there are some limitations of PEEK including their bio-inert nature and impediment to host bone integration.This study aimed to evaluate the degradation profile and osteoinductive potential of biodegradable Mg-Zn-Nd-Zr cages with/without micro-arc oxidation(MAO)coatings.The Mg-Zn-Nd-Zr alloy cages,whether coated with MAO or not,demonstrated commendable biocompatibility and biomechanical properties.Immersion and electrochemical tests show better corrosion resistance of MAO coatings in vitro.mRNA sequencing,RT-qPCR and Western blotting revealed that Mg-Zn-Nd-Zr and Mg-Zn-Nd-Zr/MAO had a better effectiveness on osteoinductivity.In vivo evaluations in ovine models over 12 weeks and 24 weeks post-implantation revealed radiological and histological evidence of enhanced bone formation adjacent to the Mg-Zn-Nd-Zr alloy cages compared to PEEK counterparts.Moreover,the MAO-coated cages exhibited a reduced propensity for gas formation.The Mg-Zn-Nd-Zr alloy is as a superior osteoinductive material compared with PEEK,with the MAO coating offering an advantage in mitigating gas production.Nonetheless,further research is warranted to refine the alloy's composition or surface treatments,particularly to address the challenges associated with rapid gas evolution during the early post-implantation period.展开更多
Creating economical and effective catalysts for the oxygen evolution reaction(OER)is essential for enhancing the efficiency of electrochemical water splitting.In this study,we designed a multicomponent heterogeneous i...Creating economical and effective catalysts for the oxygen evolution reaction(OER)is essential for enhancing the efficiency of electrochemical water splitting.In this study,we designed a multicomponent heterogeneous interfacial catalyst,Ni(OH)_(2)/NiCo(OH)_(6)@FeOOH,using a simple two-step method.In situ Raman and X-ray photoelectron spectroscopy(XPS)measurements revealed the dynamic phase change occurring during the OER process.The FeOOH layer on Ni(OH)_(2)/NiCo(OH)_(6)altered the electronic structure,facilitating the emergence of the active NiOOH phase and markedly improving OER kinetics.Significantly,the Ni(OH)_(2)/NiCo(OH)_(6)@FeOOH 2:1 catalyst demonstrated a current density of 10 mA·cm^(-2)at an overpotential of merely 208 mV,accompanied by a Tafel slope of 37.72 mV·dec-1,exhibiting exceptional stability over a duration of 100 h at 10 mA·cm^(-2).Furthermore,the Ni(OH)_(2)/NiCo(OH)_(6)@FeOOH 2:1(+)lIPt/C(-)electrolyzer cell showcased a remarkably low driving voltage of 1.52 V to achieve 10 mA·cm^(-2),while also displaying impressive durability under alkaline conditions for over100 h.This work enhances our understanding of the interfacial structure-activity relationship in composite catalysts,aiding the design of efficient catalysts with rapid kinetics.展开更多
The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the...The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.展开更多
Welcome to the 20th China-Europe International Symposium on Software Engineering Education in 2024(CEISEE 2024).Education on software and IT industry has been a hot topic in the Internet plus and big data time.CEISEE ...Welcome to the 20th China-Europe International Symposium on Software Engineering Education in 2024(CEISEE 2024).Education on software and IT industry has been a hot topic in the Internet plus and big data time.CEISEE has become a very good platform for the attendees from educational institutes,software industry and educational authorities from both Europe and China to exchange their visions and wisdom,to share their experiences,and to discuss their approaches for the software engineering education and university-industry cooperation.展开更多
本文运用Citespace文献计量分析软件,以《Information Systems Research》(简称ISR)期刊在1998年至2017年近20年收录的747篇文献为研究对象,从文献产出分析、国家合作网络分析、机构合作网络分析和引文网络聚类分析四个方面进行研究,研...本文运用Citespace文献计量分析软件,以《Information Systems Research》(简称ISR)期刊在1998年至2017年近20年收录的747篇文献为研究对象,从文献产出分析、国家合作网络分析、机构合作网络分析和引文网络聚类分析四个方面进行研究,研究结果表明:1) 根据文献产出分析,ISR期刊的文献产出量呈现波动性增长;2) 根据国家合作网络分析,美国在国家合作网络中是核心节点,中国需要加强国际合作,提高自身影响力;3) 在研究机构合作网络中,文献产出量前五所高校均位于美国,同时根据合作网络中心性分析,中心性在0.1以上的12所机构中,9所位于美国,中国只有香港城市大学列于其中,另外,德克萨斯大学达拉斯分校、佐治亚理工学院、新加坡国立大学和德克萨斯大学奥斯汀分校,在信息系统领域研究潜力巨大;4) 根据引文网络聚类分析,研究热点的演变可分为三个阶段:1998年至2001年期间信息系统领域研究的重心在信息系统的企业应用,2002年至2011年期间研究重心由传统的组织转移到虚拟组织的测量指标、信任和影响因素,2012年至2017年期间由电子口碑研究转向在线知识社区中的知识扩散研究。展开更多
Resilient wheels are extensively used in urban rail transit, especially for tramway systems, owing to its advantages in noise reduction. A new type of resilient wheel for a metro is designed, and its characteristics o...Resilient wheels are extensively used in urban rail transit, especially for tramway systems, owing to its advantages in noise reduction. A new type of resilient wheel for a metro is designed, and its characteristics of vibration and sound radiation, including the rolling noise of a resilient single wheel coupled with a track, are studied in this paper. A two-step research is presented. Firstly, laboratory experiments were conducted to obtain the vibration response of the designed resilient wheel under the radial excitation on its tread. Secondly, the rolling noise model of the resilient wheel coupled with a slab track used in a metro line is developed. The wheel model is based on the 3 D finite elementand boundary element methods and verified by using the experimental results obtained from the laboratory. The track vibration model is based on the wavenumber finite element method, and the track sound radiation is calculatedby using an e cient frequency-domain Rayleigh method. The interaction of the resilient wheel and the slab track is analyzed considering the measured wheel/rail roughness of the metro. The contribution of the resilient wheel to the reduction of wheel/rail system noise is analyzed. The results show that the resilient wheel can e ectively reduce the wheel/rail rolling noise by approximately 2 dB(A) to 3 dB(A), mainly because the radiated noise by the rail is reduced. In addition, the elastic modulus of the rubber has an important influence on the noise reduction of resilient wheels.展开更多
Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on so...Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid （PLFA） abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed ＂U＂ shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram＋ to Gram- bacteria, formed ＂∩＂ shaped quadratic functions, and the ratio of cy17：0 to 16： 1ω7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiobydrolase activity formed ＂U＂ shaped quadratic functions. Soil N：P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N：P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.展开更多
This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates（50 mm thick） by using finite element and contour measurement methods.A three-dimensional finite element model of 50-...This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates（50 mm thick） by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.展开更多
In this study,the effects of soluble readily biodegradable COD(sCOD)and particulate slowly biodegradable COD(pCOD)on anammox process were investigated.The results of the longterm experiment indicated that a low sCOD/N...In this study,the effects of soluble readily biodegradable COD(sCOD)and particulate slowly biodegradable COD(pCOD)on anammox process were investigated.The results of the longterm experiment indicated that a low sCOD/N ratio of 0.5 could accelerate the anammox and denitrification activity,to reach as high as 84.9%±2.8%TN removal efficiency.Partial denitrification-anammox(PDN/anammox)and denitrification were proposed as the major pathways for nitrogen removal,accounting for 91.3% and 8.7% of the TN removal,respectively.Anammox bacteria could remain active with high abundance of anammox genes to maintain its dominance.Candidatus Kuenenia and Thauera were the predominant genera in the presence of organic matter.Compared with sCOD,batch experiments showed that the introduction of pCOD had a negative effect on nitrogen removal.The contribution of denitrification to nitrogen removal decreased from approximately 14%to 3% with increasing percentage of pCOD.In addition,the analysis result of the process data using an optimized ASM1 model indicated that high percentage of pCOD resulted in serious N_(2)O emission(the peak value up to 0.25mg N/L),whichwas likely due to limited mass diffusion and insufficient available carbon sources for denitrification.However,a high sCOD/N ratio was beneficial for alleviating N_(2)O accumulation.展开更多
In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited t...In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited the proliferation and viability of hippocampal neurons. Terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling assay demonstrated that hypoxia induced neuronal apoptosis in a time-dependent manner, with a greater number of apoptotic cells with longer hypoxic exposure. Immunofluorescence labeling revealed that hypoxia suppressed TYRO3 expression. Western blot assay showed that hypoxia decreased Akt phosphorylation levels in a time-dependent manner. Taken together, these findings suggest that hypoxia inhibits the proliferation of hippocampal neurons and promotes apoptosis, and that the inhibition of the TYRO3/Akt signaling pathway plays an important role in hypoxia-induced neuronal injury.展开更多
基金financially supported by the Natural Science Basic Research Program of Shaanxi Province,China(No.2023-JC-QN-0581)Advanced Power Specialty,China(No.YK22C-9)。
文摘The microstructure evolution and strengthening mechanism of WE54 alloy with different hard-plate rolling(HPR)processes were systematically investigated.The results suggest that the mechanical properties of the as-rolled alloys are significantly enhanced compared to those of the as-cast alloy.When subjected to three rolling passes at 450℃ and 490℃,grain refinement occurs due to dynamic recrystallization.A mixed-grain structure is formed after a single pass rolling with a substantial reduction(65%)at 490℃.The dynamic recrystallization(DRX)mechanism of the alloy during the HPR includes continuous dynamic recrystallization(CDRX),discontinuous dynamic recrystallization(DDRX),and twin-induced recrystallization(TDRX).The WE54 alloy exhibits the highest strength after three passes of HPR at 450℃,with tensile strength and yield strength of 374 and 323 MPa,respectively.The significant improvement in the mechanical properties of the alloy is primarily attributed to fine-grain strengthening,solid solution strengthening,and dislocation strengthening.
基金the National Key Research and Development Program of China(Grant No.2023YFF1303501)the National Science Fund for Distinguished Young Scholars of China(Grant No.42225702)the Open Fund of State Key Laboratory of Frozen Soil Engineering(Grant No.SKLFSE201814).
文摘Frost heave and thaw settlement in cold regions pose a significant threat to engineering construction.Optical frequency domain reflectometry(OFDR)based on Rayleigh scattering can be applied to monitor ground deformation in frozen soil areas,where the interface behavior of soil-embedded fiber optic sensors governs the monitoring accuracy.In this paper,a series of pullout tests were conducted on fiber optic(FO)cables embedded in the frozen soil to investigate the cable‒soil interface behavior.An experimental study was performed on interaction effects,particularly focused on the water content of unfrozen soil,freezing duration,and differential distribution of water content in frozen soil.The highresolution axial strains of FO cables were obtained using a sensing interrogator,and were used to calculate the interface shear stress.The interfacial mechanical response was analytically modeled using the ideal elasto‒plastic and softening constitutive models.Three freezing periods,correlating with the phase change process between ice and water,were analyzed.The results shows that the freezing effect can amplify the peak shear stress at the cable-soil interface by eight times.A criterion for the interface coupling states was proposed by normalizing the pullout force‒displacement information.Additionally,the applicability of existing theoretical models was discussed by comparing the results of theoretical back‒calculations with experimental measurements.This study provides new insights into the progressive interfacial failure behavior between strain sensing cable and frozen soil,which can be used to assist the interpretation of FO monitoring results of frozen soil deformation.
基金supported by the National Natural Science Foundation of China(82172392)the National Natural Science Foundation of China(82372401)+1 种基金the Beijing Natural Science Foundation(L202033)the Basic Applied Research Program of Liaoning Province of China(2022020347-JH2/1013)。
文摘Interbody fusion is recognized as the golden standard of surgical intervention for degenerative disc disease(DDD).Interbody fusion cage made of polyetheretherketone(PEEK)is commonly used in lumbar interbody fusion surgery in the treatment of DDD worldwide.However,there are some limitations of PEEK including their bio-inert nature and impediment to host bone integration.This study aimed to evaluate the degradation profile and osteoinductive potential of biodegradable Mg-Zn-Nd-Zr cages with/without micro-arc oxidation(MAO)coatings.The Mg-Zn-Nd-Zr alloy cages,whether coated with MAO or not,demonstrated commendable biocompatibility and biomechanical properties.Immersion and electrochemical tests show better corrosion resistance of MAO coatings in vitro.mRNA sequencing,RT-qPCR and Western blotting revealed that Mg-Zn-Nd-Zr and Mg-Zn-Nd-Zr/MAO had a better effectiveness on osteoinductivity.In vivo evaluations in ovine models over 12 weeks and 24 weeks post-implantation revealed radiological and histological evidence of enhanced bone formation adjacent to the Mg-Zn-Nd-Zr alloy cages compared to PEEK counterparts.Moreover,the MAO-coated cages exhibited a reduced propensity for gas formation.The Mg-Zn-Nd-Zr alloy is as a superior osteoinductive material compared with PEEK,with the MAO coating offering an advantage in mitigating gas production.Nonetheless,further research is warranted to refine the alloy's composition or surface treatments,particularly to address the challenges associated with rapid gas evolution during the early post-implantation period.
基金financially supported by the National Natural Science Foundation of China(Nos.52306142,52272202 and W2421027)Yunnan Major Scientific and Technological Projects(No.202202AG050017-02)+2 种基金Yunnan Fundamental Research Projects(No.202101BE070001-017)the Science and Technology Innovation and Entrepreneurship Fund of China Coal Technology&Engineering Group Co.,Ltd.(Nos.2022-MS002 and 2023-TD-MS007)Bintuan Science and Technology Program(No.2022DB009)
文摘Creating economical and effective catalysts for the oxygen evolution reaction(OER)is essential for enhancing the efficiency of electrochemical water splitting.In this study,we designed a multicomponent heterogeneous interfacial catalyst,Ni(OH)_(2)/NiCo(OH)_(6)@FeOOH,using a simple two-step method.In situ Raman and X-ray photoelectron spectroscopy(XPS)measurements revealed the dynamic phase change occurring during the OER process.The FeOOH layer on Ni(OH)_(2)/NiCo(OH)_(6)altered the electronic structure,facilitating the emergence of the active NiOOH phase and markedly improving OER kinetics.Significantly,the Ni(OH)_(2)/NiCo(OH)_(6)@FeOOH 2:1 catalyst demonstrated a current density of 10 mA·cm^(-2)at an overpotential of merely 208 mV,accompanied by a Tafel slope of 37.72 mV·dec-1,exhibiting exceptional stability over a duration of 100 h at 10 mA·cm^(-2).Furthermore,the Ni(OH)_(2)/NiCo(OH)_(6)@FeOOH 2:1(+)lIPt/C(-)electrolyzer cell showcased a remarkably low driving voltage of 1.52 V to achieve 10 mA·cm^(-2),while also displaying impressive durability under alkaline conditions for over100 h.This work enhances our understanding of the interfacial structure-activity relationship in composite catalysts,aiding the design of efficient catalysts with rapid kinetics.
基金supported by the State Key Program of the National Natural Science Foundation of China(Grant Nos.42230701,91644215)the National Natural ScienceFoundation of China(Grant Nos.42122062 and 42307137)+3 种基金the Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010852)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.23hytd002)the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant No.SML2023SP218)L.M.acknowledges the Zhuhai Science and Technology Plan Project(Grant No.ZH22036201210115PWC).
文摘The compositions and distributions of monoterpenes,isoprene,aromatics and sesquiterpene SOA tracers(SOAM,SOAI,SOAA and SOAS,respectively)at an island site(Da Wan Shan Island,DWS)were investigated in the context of the influence of continental and marine air masses over the Pearl River Estuary(PRE)region in winter 2021.The sum concentration of SOA tracers was 6.2–132.8 ng m^(−3),with SOAM and SOAI as the main components in both continental(scenarios A1 and A2)and marine air masses(scenario A3),as well as their combination(scenario A4).The highest and lowest levels of SOAM were observed in A1 and A3,respectively,which were mainly related to the variations in meteorological conditions,precursor concentrations,and the degree of photochemical processes.Higher MBTCA/HGA(3-methyl-1,2,3-butanetricarboxylic acid/3-hydroxyglutaric acid)ratios suggested a less significant contribution fromα-pinene to SOAM.The variations of SOAI in the different scenarios were associated with differences in relative humidity,particle acidity,and isoprene/NOx ratios.The respective highest and lowest concentrations of aromatics SOA tracers in A1 and A3 revealed the influence of anthropogenic precursors from upwind continental areas,which was confirmed by the correlation among biogenic and anthropogenic precursors.The results of the tracer-based-method suggested dominant contributions of SOAs from aromatics and monoterpenes,with the highest concentrations in A1.A WRF-Chem simulation revealed that the SOAs from the above precursors only contributed 12%–25%to the total SOA at DWS,while the spatial distributions of SOAs further highlighted that the abundance of SOAs over the PRE region in winter is highly associated with air masses transported from upwind continental areas.
文摘Welcome to the 20th China-Europe International Symposium on Software Engineering Education in 2024(CEISEE 2024).Education on software and IT industry has been a hot topic in the Internet plus and big data time.CEISEE has become a very good platform for the attendees from educational institutes,software industry and educational authorities from both Europe and China to exchange their visions and wisdom,to share their experiences,and to discuss their approaches for the software engineering education and university-industry cooperation.
基金the support from Human Resources and Social Security Department of Hebei Province, which identified the first author as senior visiting scholarthe Service Center for Experts and Scholars of Hebei Province for financial support, and the College of Business, Dublin Institute of Technology for providing a research place to the first author
基金Supported by National Key R&D Program of China(Grant No.2017YFB1201103-08)National Nature Science Foundation of China(Grant No.51605318)
文摘Resilient wheels are extensively used in urban rail transit, especially for tramway systems, owing to its advantages in noise reduction. A new type of resilient wheel for a metro is designed, and its characteristics of vibration and sound radiation, including the rolling noise of a resilient single wheel coupled with a track, are studied in this paper. A two-step research is presented. Firstly, laboratory experiments were conducted to obtain the vibration response of the designed resilient wheel under the radial excitation on its tread. Secondly, the rolling noise model of the resilient wheel coupled with a slab track used in a metro line is developed. The wheel model is based on the 3 D finite elementand boundary element methods and verified by using the experimental results obtained from the laboratory. The track vibration model is based on the wavenumber finite element method, and the track sound radiation is calculatedby using an e cient frequency-domain Rayleigh method. The interaction of the resilient wheel and the slab track is analyzed considering the measured wheel/rail roughness of the metro. The contribution of the resilient wheel to the reduction of wheel/rail system noise is analyzed. The results show that the resilient wheel can e ectively reduce the wheel/rail rolling noise by approximately 2 dB(A) to 3 dB(A), mainly because the radiated noise by the rail is reduced. In addition, the elastic modulus of the rubber has an important influence on the noise reduction of resilient wheels.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Science (No.KZCX2-EW-QN406)the National Natural Science Foundation of China (No.31170425,40871130)
文摘Many studies have shown soil degradation after the conversion of native forests to exotic Eucalyptus plantations. However, few studies have investigated the long-term impacts of short-rotation forestry practices on soil microorganisms. The impacts of Eucalyptus successive rotations on soil microbial communities were evaluated by comparing phospholipid fatty acid （PLFA） abundances, compositions, and enzyme activities of native Pinus massoniana plantations and adjacent 1st, 2nd, 3rd, 4th generation Eucalyptus plantations. The conversion from P. massoniana to Eucalyptus plantations significantly decreased soil microbial community size and enzyme activities, and increased microbial physiological stress. However, the PLFA abundances formed ＂U＂ shaped quadratic functions with Eucalyptus plantation age. Alternatively, physiological stress biomarkers, the ratios of monounsaturated to saturated fatty acid and Gram＋ to Gram- bacteria, formed ＂∩＂ shaped quadratic functions, and the ratio of cy17：0 to 16： 1ω7c decreased with plantation age. The activities of phenol oxidase, peroxidase, and acid phosphatase increased with Eucalyptus plantation age, while the cellobiobydrolase activity formed ＂U＂ shaped quadratic functions. Soil N：P, alkaline hydrolytic nitrogen, soil organic carbon, and understory cover largely explained the variation in PLFA profiles while soil N：P, alkaline hydrolytic nitrogen, and understory cover explained most of the variability in enzyme activity. In conclusion, soil microbial structure and function under Eucalyptus plantations were strongly impacted by plantation age. Most of the changes could be explained by altered soil resource availability and understory cover associated with successive planting of Eucalyptus. Our results highlight the importance of plantation age for assessing the impacts of plantation conversion as well as the importance of reducing disturbance for plantation management.
基金supported by the National Natural Science Foundation of China (No.50935008)
文摘This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates（50 mm thick） by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.
基金supported by the National Science Foundation of China (Nos. 51978487 and 51678424)National Key Research and Development Program of China (No. 2019YFC1906402)the National Science Centre (No. 2017/26/D/ST8/00967)
文摘In this study,the effects of soluble readily biodegradable COD(sCOD)and particulate slowly biodegradable COD(pCOD)on anammox process were investigated.The results of the longterm experiment indicated that a low sCOD/N ratio of 0.5 could accelerate the anammox and denitrification activity,to reach as high as 84.9%±2.8%TN removal efficiency.Partial denitrification-anammox(PDN/anammox)and denitrification were proposed as the major pathways for nitrogen removal,accounting for 91.3% and 8.7% of the TN removal,respectively.Anammox bacteria could remain active with high abundance of anammox genes to maintain its dominance.Candidatus Kuenenia and Thauera were the predominant genera in the presence of organic matter.Compared with sCOD,batch experiments showed that the introduction of pCOD had a negative effect on nitrogen removal.The contribution of denitrification to nitrogen removal decreased from approximately 14%to 3% with increasing percentage of pCOD.In addition,the analysis result of the process data using an optimized ASM1 model indicated that high percentage of pCOD resulted in serious N_(2)O emission(the peak value up to 0.25mg N/L),whichwas likely due to limited mass diffusion and insufficient available carbon sources for denitrification.However,a high sCOD/N ratio was beneficial for alleviating N_(2)O accumulation.
基金supported by the National Natural Science Foundation of China,No.81001541the Natural Science Foundation of Fujian Province of China,No.2013J01331
文摘In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited the proliferation and viability of hippocampal neurons. Terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling assay demonstrated that hypoxia induced neuronal apoptosis in a time-dependent manner, with a greater number of apoptotic cells with longer hypoxic exposure. Immunofluorescence labeling revealed that hypoxia suppressed TYRO3 expression. Western blot assay showed that hypoxia decreased Akt phosphorylation levels in a time-dependent manner. Taken together, these findings suggest that hypoxia inhibits the proliferation of hippocampal neurons and promotes apoptosis, and that the inhibition of the TYRO3/Akt signaling pathway plays an important role in hypoxia-induced neuronal injury.
