In the construction of the Qinghai-Tibet Power Transmission Line (QTPTL), cast-in-place piles (CIPPs) are widely applied in areas with unfavorable geological conditions. The thermal regime around piles in permafro...In the construction of the Qinghai-Tibet Power Transmission Line (QTPTL), cast-in-place piles (CIPPs) are widely applied in areas with unfavorable geological conditions. The thermal regime around piles in permafrost regions greatly affects the stability of the towers as well as the operation of the QTPTL. The casting of piles will markedly affect the thermal regime of the surrounding permafrost because of the casting temperature and the hydration heat of cement. Based on the typical geological and engineering conditions along the QTPTL, thermal disturbance ofa CIPP to surrounding permafrost under different casting seasons, pile depths, and casting temperatures were simulated. The results show that the casting season (summer versus winter) can influence the refreezing process of CIPPs, within the first 6 m of pile depth. Sixty days after being cast, CIPPs greater than 6 m in depth can be frozen regardless of which season they were cast, and the foundation could be reffozen after a cold season. Comparing the refreezing characteristics of CIPPs cast in different seasons also showed that, without considering the ground surface conditions, warm seasons are more suitable for casting piles. With the increase of pile depth, the thermal effect of a CIPP on the surrounding soil mainly expands vertically, while the lateral heat disturbance changes little. Deeper, longer CIPPs have better stability. The casting temperature clearly affects the thermal disturbance, and the radius of the melting circle increases with rising casting temperature. The optimal casting temperature is between 2 ℃ and 9 ℃.展开更多
Many staircases in reinforced concrete (RC) frame structures suffered severe damage during the Wenchuan earthquake. Elastic analyses for 18 RC structure models with and without staircases are conducted and compared ...Many staircases in reinforced concrete (RC) frame structures suffered severe damage during the Wenchuan earthquake. Elastic analyses for 18 RC structure models with and without staircases are conducted and compared to study the influence of the staircase on the stiffness, displacements and internal forces of the structures. To capture the yielding development and damage mechanism of frame structures, elasto-plastic analysis is carried out for one of the 18 models. Based on the features observed in the analyses, a new type of staircase design i.e., isolating them from the master structure to eliminate the effect of K-type struts, is proposed and discussed. It is concluded that the proposed method of staircase isolation is effective and feasible for engineering design, and does not significantly increase the construction cost.展开更多
Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor ha...Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor have been done on this new kind of floor system in this paper. The experiment results show that the floor system has good mechanical property such as high bearing capacity, big rigidity and good tensility. A theoretical method is presented in this paper that the stiffening-ribbed-hollow-pipe girderless floor can be analyzed by being converted equivalently to orthotropic solid slab. It is indicated that the method is correct and reasonable according to the contrast between theoretical calculated results and experimental measured results. The theoretical results coincide with the measured results well.展开更多
Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies i...Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies indicated that this method is too conservative. Only when the pile cap is elevated from the ground level,the raft bearing contribution can be neglected. In a piled raft foundation, pileesoileraft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focused on steel piles. The present study aims to compare the behaviors of piled raft foundations with free-standing pile groups in sand, using laboratory physical models. Cast-in-place concrete piles and concrete raft are used for the tests. The tests are conducted on single pile, single pile in pile group, unpiled raft, free-standing pile group and piled raft foundation. We examine the effects of the number of piles, the pile installation method and the interaction between different components of foundation. The results indicate that the ultimate bearing capacity of the piled raft foundation is considerably higher than that of the free-standing pile group with the same number of piles. With installation of the single pile in the group, the pile bearing capacity and stiffness increase. Installation of the piles beneath the raft decreases the bearing capacity of the raft. When the raft bearing capacity is not included in the design process, the allowable bearing capacity of the piled raft is underestimated by more than 200%. This deviation intensifies with increasing spacing of the piles.展开更多
The paper investigated"The Third Place"within Chinese language students' community in the university of Newcastle(Uo N). Through the investigation, critical analysis has been given by comparing the behav...The paper investigated"The Third Place"within Chinese language students' community in the university of Newcastle(Uo N). Through the investigation, critical analysis has been given by comparing the behaviour and performance of two types of Chinese students within the community. Moreover, critical questions have arisen: Is the teacher in the language room really the best catalyst to create"The Third Place"? How should Chinese students make use of wider context to contest their native culture? The paper further described a sociocultural framework which indicates"The Third Place"should not be an isolated knowledge to be learn, but happens through constant information exchange with the outside world and socialising. Critical applications have also been given to guide how to make"The Third Place"occur within Chinese language community smoothly.展开更多
This paper aims to deal with the assessment of axial load capacity for cast in place pile foundations, which are made by the earth drill method, by using the data taken from Standard Penetration Tests (SPTs) and Piezo...This paper aims to deal with the assessment of axial load capacity for cast in place pile foundations, which are made by the earth drill method, by using the data taken from Standard Penetration Tests (SPTs) and Piezocone Penetration Tests (CPTUs). These tests were carried out as part of the investigation program for P.N.G. Terminal-Power Plant, near Semani beach, in Hoxhara marsh, in the western part of Albania. The design of axial load capacity of piles is based on empirical formula using SPT and CPTU values. This study presents the results of axial load capacity analysis of cast in place piles by different analytical calculation methods, which are based on in situ tests results, and also referring to the Building Standard Law of Japan. In the end of our work, differences between calculations methods by using different in situ tests results are shown in tables and graphs.展开更多
This paper expatiated the field test of large diameter cast in place piles embedded in soft rock, including static loading test, high or low strain dynamic test, measurement of stresses and strains of pile body, and p...This paper expatiated the field test of large diameter cast in place piles embedded in soft rock, including static loading test, high or low strain dynamic test, measurement of stresses and strains of pile body, and pressure measurements between pile tip and soft rock. The relative in situ test problems are discussed. Based on the limit equilibrium theory and the load transfer equation, a synthesis method of analyzing the ultimate carrying capacity of single large diameter pile is put forward. The research results show that the key to determining the ultimate carrying capacity of single pile with a large diameter is the analysis of the intensity of soft rock.展开更多
A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present study.The ball milling and cold pressing pretreatment of the reinforcements made it feasib...A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present study.The ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good dispersion.The microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in detail.The TiB_(2) particles in the Al-TiB_(2)/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the melt.Compared with the matrix alloys,the Al-TiB_(2)/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable elongation.The strengthening effect in the composites was mainly attributed to the strong grain refining effect of TiB2.This work shows a balance of high specific modulus(36.1 GPa·cm^(3)·g^(-1))and elongation(8.4%)with the conventional stir casting path,which is of considerable application value.展开更多
The energy pile is a kind of building energy-saving technology using shallow geothermal energy,and its heat exchange performance is an important factor affecting its development.In this study,heat exchange tests were ...The energy pile is a kind of building energy-saving technology using shallow geothermal energy,and its heat exchange performance is an important factor affecting its development.In this study,heat exchange tests were carried out on three full-size cast-in place energy piles,and the influence of various factors on the heat exchange amount and the heat exchange rate was analyzed.The following conclusions are drawn:(1)the heat exchange rate of the cast-in place energy pile is greatly affected by the inlet water temperature;(2)increasing the pile length can increase the heat exchange amount,but has little effect on improving the heat exchange rate;(3)the increase in the heat exchange amount by heat exchange pipes in series is not significant,and therefore the parallel-type heat exchange pipes should be considered in practical engineering;(4)the appropriate circulating water flow velocity gives the best heat exchange efficiency.展开更多
The complex sand-casting process combined with the interactions between process parameters makes it difficult to control the casting quality,resulting in a high scrap rate.A strategy based on a data-driven model was p...The complex sand-casting process combined with the interactions between process parameters makes it difficult to control the casting quality,resulting in a high scrap rate.A strategy based on a data-driven model was proposed to reduce casting defects and improve production efficiency,which includes the random forest(RF)classification model,the feature importance analysis,and the process parameters optimization with Monte Carlo simulation.The collected data includes four types of defects and corresponding process parameters were used to construct the RF model.Classification results show a recall rate above 90% for all categories.The Gini Index was used to assess the importance of the process parameters in the formation of various defects in the RF model.Finally,the classification model was applied to different production conditions for quality prediction.In the case of process parameters optimization for gas porosity defects,this model serves as an experimental process in the Monte Carlo method to estimate a better temperature distribution.The prediction model,when applied to the factory,greatly improved the efficiency of defect detection.Results show that the scrap rate decreased from 10.16% to 6.68%.展开更多
The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on sin...The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.展开更多
The place and placeness are believed to be a crucial perspective for comprehending the transformative dynamics of tourist destinations in the context of globalization and the rapid development of the tourism industry....The place and placeness are believed to be a crucial perspective for comprehending the transformative dynamics of tourist destinations in the context of globalization and the rapid development of the tourism industry.As the material carrier of language,linguistic landscape is an intermediary for people to endow emotions and personalities into the place,becoming an effective path for exploring the place-making in a certain area.Mogan Mountain is a famous national tourist resort,which is located in Mogan Mountain Town,Deqing County,Huzhou City,China.This is a good case area for studying the relationship between linguistic landscape and placemaking in tourist destinations.There are two theories that form the theoretical foundation of the study,namely the place and the geosemiotics.Firstly,the results showed the overall style of the linguistic landscape.Multilingual labelling(52.7%),official signs(55.3%),and standardized Chinese characters predominantly shaped the linguistic landscape,with English and other languages being complementary.Secondly,from the perspective of three dimensions of the geosemiotics framework,such as inscription,language preference,and placement position,we conduct a comprehensive semiotic analysis of the linguistic landscape,which encompasses diverse facets such as fonts,materials,shifts in state,text vectors,and symmetrical arrangements.Finally,we explore the influence of linguistic landscapes on the place-making of Mogan Mountain through the dimensions of location,locale,and sense of place.The information on linguistic landscapes indicates the geographical location.These linguistic landscapes play an important role in constructing the language order,nostalgic atmosphere,exotic atmosphere,and elegant and tasteful lifestyle of the public space in Mogan Mountain.Readers of linguistic landscapes,including tourists and residents,generate and identify with the unique sense of place in Mogan Mountain.These linguistic landscapes construct the destination placeness of Mogan Mountain that combines both foreign and nostalgic styles,and the integration of Chinese and Western cultures.It will help promote the image positioning of tourism destinations and have practical guiding significance for the tourism planning,landscape-making,language management,and other aspects of tourism destinations.展开更多
Emerging technological advances are reshaping the casting sector in latest decades.Casting technology is evolving towards intelligent casting paradigm that involves automation,greenization and intelligentization,which...Emerging technological advances are reshaping the casting sector in latest decades.Casting technology is evolving towards intelligent casting paradigm that involves automation,greenization and intelligentization,which attracts more and more attention from the academic and industry communities.In this paper,the main features of casting technology were briefly summarized and forecasted,and the recent developments of key technologies and the innovative efforts made in promoting intelligent casting process were discussed.Moreover,the technical visions of intelligent casting process were also put forward.The key technologies for intelligent casting process comprise 3D printing technologies,intelligent mold technologies and intelligent process control technologies.In future,the intelligent mold that derived from mold with sensors,control devices and actuators will probably incorporate the Internet of Things,online inspection,embedded simulation,decision-making and control system,and other technologies to form intelligent cyber-physical casting system,which may pave the way to realize intelligent casting.It is promising that the intelligent casting process will eventually achieve the goal of real-time process optimization and full-scale control,with the defects,microstructure,performance,and service life of the fabricated castings can be accurately predicted and tailored.展开更多
To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wh...To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting process.The effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in detail.In each rotation,the casting wheel passes through four different spray zones.The results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,respectively.The temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.展开更多
The present study has been carried out on a total of 50 available plant species to assess their dust-capturing capacity and biochemical performances in and around open cast granite mine areas of Jhansi district and Bu...The present study has been carried out on a total of 50 available plant species to assess their dust-capturing capacity and biochemical performances in and around open cast granite mine areas of Jhansi district and Bundelkhand University campus treated as control site. Plant species existing under a polluted environment for a long time may be considered as potentially resistant species and recommended for green belt design in mining areas, especially to cope with dust pollution. Results showed the pollution level, especially of mining-originated dust particles holding capacity of leaves and effects of different biochemical parameters (Total Chlorophyll, Protein and Carotenoid) of existing plant species both from mining areas as well as from Bundelkhand University campus. Based on their performances, Tectona grandis L., Ficus hispida L., Calotropis procera Aiton., Butea monosperma Lam. and Ficus benghalensis L., etc. are highly tolerant species while Ficus infectoria L., Artocarpus heterophyllus Lam., Ipomoea purpurea L., Allianthus excelsa Roxb. and Bauhinia variegata L. are intermediate tolerant species. T. grandis had shown the highest dust-holding capacity (2.566 ± 0.0004 mg/cm2) whereas Albizia procera (0.018 ± 0.0002 mg/cm2) was found to be the lowest dust-holding capacity. Our findings also showed that the T. grandis and F. hispida have significant dust deposition with minimal effect of dust on their leaf chlorophyll (17.447 ± 0.019 mg/g and 14.703 ± 0.201 mg/g), protein (0.699 ± 0.001 mg/g and 0.604 ± 0.002 mg/g) and carotenoid (0.372 ± 0.003 mg/g and 0.354 ± 0.003 mg/g) content respectively among all selected plant species. Therefore, in the present investigation, plant species with high tolerance to high dust-holding capacity on their leaf surfaces are preferable for green corridors as open cast granite mines and their adjacent areas.展开更多
Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural comp...Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and manufacturing.This paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and benefits.Factors affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and performance.Metallurgical analysis and mechanical property assessment of an ultra-large aluminum shape casting are presented.Challenges are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.展开更多
基金supported by the National Key Basic Research Program of China (973 Program) (No.2012CB026106)the National Natural Science Foundation of China (Grant No. 41171059)the Fund of the State Key Laboratory of Frozen Soil Engineering (No. SKLFSE-ZY-16)
文摘In the construction of the Qinghai-Tibet Power Transmission Line (QTPTL), cast-in-place piles (CIPPs) are widely applied in areas with unfavorable geological conditions. The thermal regime around piles in permafrost regions greatly affects the stability of the towers as well as the operation of the QTPTL. The casting of piles will markedly affect the thermal regime of the surrounding permafrost because of the casting temperature and the hydration heat of cement. Based on the typical geological and engineering conditions along the QTPTL, thermal disturbance ofa CIPP to surrounding permafrost under different casting seasons, pile depths, and casting temperatures were simulated. The results show that the casting season (summer versus winter) can influence the refreezing process of CIPPs, within the first 6 m of pile depth. Sixty days after being cast, CIPPs greater than 6 m in depth can be frozen regardless of which season they were cast, and the foundation could be reffozen after a cold season. Comparing the refreezing characteristics of CIPPs cast in different seasons also showed that, without considering the ground surface conditions, warm seasons are more suitable for casting piles. With the increase of pile depth, the thermal effect of a CIPP on the surrounding soil mainly expands vertically, while the lateral heat disturbance changes little. Deeper, longer CIPPs have better stability. The casting temperature clearly affects the thermal disturbance, and the radius of the melting circle increases with rising casting temperature. The optimal casting temperature is between 2 ℃ and 9 ℃.
基金The National Key Technologies R&D Program under Grant No. 2009BAJ28B01The Technologies R&D Program of China State Construction Engineering Co., Ltd under Grant No. CSCEC-2009-Z-15
文摘Many staircases in reinforced concrete (RC) frame structures suffered severe damage during the Wenchuan earthquake. Elastic analyses for 18 RC structure models with and without staircases are conducted and compared to study the influence of the staircase on the stiffness, displacements and internal forces of the structures. To capture the yielding development and damage mechanism of frame structures, elasto-plastic analysis is carried out for one of the 18 models. Based on the features observed in the analyses, a new type of staircase design i.e., isolating them from the master structure to eliminate the effect of K-type struts, is proposed and discussed. It is concluded that the proposed method of staircase isolation is effective and feasible for engineering design, and does not significantly increase the construction cost.
文摘Stiffening-ribbed-hollow-pipe cast-in place reinforced concrete girderless floor is a new-style hollow girderless floor system. Model experimental researches of simply-supported floor and four-corners bearing floor have been done on this new kind of floor system in this paper. The experiment results show that the floor system has good mechanical property such as high bearing capacity, big rigidity and good tensility. A theoretical method is presented in this paper that the stiffening-ribbed-hollow-pipe girderless floor can be analyzed by being converted equivalently to orthotropic solid slab. It is indicated that the method is correct and reasonable according to the contrast between theoretical calculated results and experimental measured results. The theoretical results coincide with the measured results well.
文摘Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies indicated that this method is too conservative. Only when the pile cap is elevated from the ground level,the raft bearing contribution can be neglected. In a piled raft foundation, pileesoileraft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focused on steel piles. The present study aims to compare the behaviors of piled raft foundations with free-standing pile groups in sand, using laboratory physical models. Cast-in-place concrete piles and concrete raft are used for the tests. The tests are conducted on single pile, single pile in pile group, unpiled raft, free-standing pile group and piled raft foundation. We examine the effects of the number of piles, the pile installation method and the interaction between different components of foundation. The results indicate that the ultimate bearing capacity of the piled raft foundation is considerably higher than that of the free-standing pile group with the same number of piles. With installation of the single pile in the group, the pile bearing capacity and stiffness increase. Installation of the piles beneath the raft decreases the bearing capacity of the raft. When the raft bearing capacity is not included in the design process, the allowable bearing capacity of the piled raft is underestimated by more than 200%. This deviation intensifies with increasing spacing of the piles.
文摘The paper investigated"The Third Place"within Chinese language students' community in the university of Newcastle(Uo N). Through the investigation, critical analysis has been given by comparing the behaviour and performance of two types of Chinese students within the community. Moreover, critical questions have arisen: Is the teacher in the language room really the best catalyst to create"The Third Place"? How should Chinese students make use of wider context to contest their native culture? The paper further described a sociocultural framework which indicates"The Third Place"should not be an isolated knowledge to be learn, but happens through constant information exchange with the outside world and socialising. Critical applications have also been given to guide how to make"The Third Place"occur within Chinese language community smoothly.
文摘This paper aims to deal with the assessment of axial load capacity for cast in place pile foundations, which are made by the earth drill method, by using the data taken from Standard Penetration Tests (SPTs) and Piezocone Penetration Tests (CPTUs). These tests were carried out as part of the investigation program for P.N.G. Terminal-Power Plant, near Semani beach, in Hoxhara marsh, in the western part of Albania. The design of axial load capacity of piles is based on empirical formula using SPT and CPTU values. This study presents the results of axial load capacity analysis of cast in place piles by different analytical calculation methods, which are based on in situ tests results, and also referring to the Building Standard Law of Japan. In the end of our work, differences between calculations methods by using different in situ tests results are shown in tables and graphs.
文摘This paper expatiated the field test of large diameter cast in place piles embedded in soft rock, including static loading test, high or low strain dynamic test, measurement of stresses and strains of pile body, and pressure measurements between pile tip and soft rock. The relative in situ test problems are discussed. Based on the limit equilibrium theory and the load transfer equation, a synthesis method of analyzing the ultimate carrying capacity of single large diameter pile is put forward. The research results show that the key to determining the ultimate carrying capacity of single pile with a large diameter is the analysis of the intensity of soft rock.
基金supported by the National Natural Science Foundation of China(Nos.51821001 and U2037601)Major Scientific and Technological Inno-vation Projects in Luoyang(No.2201029A)+1 种基金Foundation Strengthening Plan Technical Field Fund(No.2021-JJ-0112)Shanghai Jiao Tong University Student Innovation Prac-tice Program(No.IPP24076).
文摘A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present study.The ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good dispersion.The microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in detail.The TiB_(2) particles in the Al-TiB_(2)/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the melt.Compared with the matrix alloys,the Al-TiB_(2)/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable elongation.The strengthening effect in the composites was mainly attributed to the strong grain refining effect of TiB2.This work shows a balance of high specific modulus(36.1 GPa·cm^(3)·g^(-1))and elongation(8.4%)with the conventional stir casting path,which is of considerable application value.
基金National Natural Science Foundation of China(No.51808203)Major Technological Innovation Projects of Hubei Province,China(No.2017AAA128)Youth Science and Technology Research Program of Hubei Education Department,China(No.Q20181405)。
文摘The energy pile is a kind of building energy-saving technology using shallow geothermal energy,and its heat exchange performance is an important factor affecting its development.In this study,heat exchange tests were carried out on three full-size cast-in place energy piles,and the influence of various factors on the heat exchange amount and the heat exchange rate was analyzed.The following conclusions are drawn:(1)the heat exchange rate of the cast-in place energy pile is greatly affected by the inlet water temperature;(2)increasing the pile length can increase the heat exchange amount,but has little effect on improving the heat exchange rate;(3)the increase in the heat exchange amount by heat exchange pipes in series is not significant,and therefore the parallel-type heat exchange pipes should be considered in practical engineering;(4)the appropriate circulating water flow velocity gives the best heat exchange efficiency.
基金financially supported by the National Key Research and Development Program of China(2022YFB3706800,2020YFB1710100)the National Natural Science Foundation of China(51821001,52090042,52074183)。
文摘The complex sand-casting process combined with the interactions between process parameters makes it difficult to control the casting quality,resulting in a high scrap rate.A strategy based on a data-driven model was proposed to reduce casting defects and improve production efficiency,which includes the random forest(RF)classification model,the feature importance analysis,and the process parameters optimization with Monte Carlo simulation.The collected data includes four types of defects and corresponding process parameters were used to construct the RF model.Classification results show a recall rate above 90% for all categories.The Gini Index was used to assess the importance of the process parameters in the formation of various defects in the RF model.Finally,the classification model was applied to different production conditions for quality prediction.In the case of process parameters optimization for gas porosity defects,this model serves as an experimental process in the Monte Carlo method to estimate a better temperature distribution.The prediction model,when applied to the factory,greatly improved the efficiency of defect detection.Results show that the scrap rate decreased from 10.16% to 6.68%.
基金Project (2007H03) supported by Communications Department of Zhejiang Province
文摘The compositions, technical principles and construction equipments of a new piling method used for ground improvement plastic tube cast-in-place concrete pile were introduced. The results from static load tests on single piles with different forms of pile shoes and on their composite foundations were analyzed. The distribution patterns of axial force, shaft friction and toe resistance were studied based on the measurements taken from buried strain gauges. From the point of engineering application, the pile has merits in convenient quality control, high bearing capacity and reliable quality, showing higher reasonability, advancement and suitability than other ground improvement methods. The pile can be adopted properly to take place of ordinary ground improvement method, achieving greater economical and social benefits.
基金the National Natural Science Foundation of China (Grant No. 41971171)The National Social Science Foundation of China (Grant No. 21BYY098) for funding support
文摘The place and placeness are believed to be a crucial perspective for comprehending the transformative dynamics of tourist destinations in the context of globalization and the rapid development of the tourism industry.As the material carrier of language,linguistic landscape is an intermediary for people to endow emotions and personalities into the place,becoming an effective path for exploring the place-making in a certain area.Mogan Mountain is a famous national tourist resort,which is located in Mogan Mountain Town,Deqing County,Huzhou City,China.This is a good case area for studying the relationship between linguistic landscape and placemaking in tourist destinations.There are two theories that form the theoretical foundation of the study,namely the place and the geosemiotics.Firstly,the results showed the overall style of the linguistic landscape.Multilingual labelling(52.7%),official signs(55.3%),and standardized Chinese characters predominantly shaped the linguistic landscape,with English and other languages being complementary.Secondly,from the perspective of three dimensions of the geosemiotics framework,such as inscription,language preference,and placement position,we conduct a comprehensive semiotic analysis of the linguistic landscape,which encompasses diverse facets such as fonts,materials,shifts in state,text vectors,and symmetrical arrangements.Finally,we explore the influence of linguistic landscapes on the place-making of Mogan Mountain through the dimensions of location,locale,and sense of place.The information on linguistic landscapes indicates the geographical location.These linguistic landscapes play an important role in constructing the language order,nostalgic atmosphere,exotic atmosphere,and elegant and tasteful lifestyle of the public space in Mogan Mountain.Readers of linguistic landscapes,including tourists and residents,generate and identify with the unique sense of place in Mogan Mountain.These linguistic landscapes construct the destination placeness of Mogan Mountain that combines both foreign and nostalgic styles,and the integration of Chinese and Western cultures.It will help promote the image positioning of tourism destinations and have practical guiding significance for the tourism planning,landscape-making,language management,and other aspects of tourism destinations.
基金funded by the Beijing Natural Science Foundation-Haidian Original Innovation Joint Fund(L212002)the Tsinghua-Toyota Joint Research Fund(20223930096)the Guangdong Provincial Key Area Research and Development Program(2022B0909070001).
文摘Emerging technological advances are reshaping the casting sector in latest decades.Casting technology is evolving towards intelligent casting paradigm that involves automation,greenization and intelligentization,which attracts more and more attention from the academic and industry communities.In this paper,the main features of casting technology were briefly summarized and forecasted,and the recent developments of key technologies and the innovative efforts made in promoting intelligent casting process were discussed.Moreover,the technical visions of intelligent casting process were also put forward.The key technologies for intelligent casting process comprise 3D printing technologies,intelligent mold technologies and intelligent process control technologies.In future,the intelligent mold that derived from mold with sensors,control devices and actuators will probably incorporate the Internet of Things,online inspection,embedded simulation,decision-making and control system,and other technologies to form intelligent cyber-physical casting system,which may pave the way to realize intelligent casting.It is promising that the intelligent casting process will eventually achieve the goal of real-time process optimization and full-scale control,with the defects,microstructure,performance,and service life of the fabricated castings can be accurately predicted and tailored.
基金financially supported by the National Natural Science Foundation of China(Grant No.U20A20289)the Innovative Research Groups Project of the Natural Science Foundation of Hebei Province(Grant No.E2021203011)the Central Government Guides Local Science and Technology Development Fund Project(Grant No.206Z1601G)。
文摘To investigate the thermal and mechanical behavior of casting wheel,a two-dimensional thermoelastic-plastic finite element model was used to predict the temperature,stress and distortion distribution of the casting wheel during the wheel and belt continuous casting process.The effects of grinding thickness and casting speed on the thermal and mechanical behaviors of the center of the hot face of the casting wheel were discussed in detail.In each rotation,the casting wheel passes through four different spray zones.The results show that the temperature distribution of the casting wheel in different spray zones is similar,the temperature of the hot face is the highest and the temperature reaches the peak in the spray zoneⅢ.The stress and distortion depend on the temperature distribution,and the maximum stress and distortion of the hot face are 358.2 MPa and 1.82 mm,respectively.The temperature at the center of the hot face decreases with increasing grinding thickness and increases with increasing casting speed.
文摘The present study has been carried out on a total of 50 available plant species to assess their dust-capturing capacity and biochemical performances in and around open cast granite mine areas of Jhansi district and Bundelkhand University campus treated as control site. Plant species existing under a polluted environment for a long time may be considered as potentially resistant species and recommended for green belt design in mining areas, especially to cope with dust pollution. Results showed the pollution level, especially of mining-originated dust particles holding capacity of leaves and effects of different biochemical parameters (Total Chlorophyll, Protein and Carotenoid) of existing plant species both from mining areas as well as from Bundelkhand University campus. Based on their performances, Tectona grandis L., Ficus hispida L., Calotropis procera Aiton., Butea monosperma Lam. and Ficus benghalensis L., etc. are highly tolerant species while Ficus infectoria L., Artocarpus heterophyllus Lam., Ipomoea purpurea L., Allianthus excelsa Roxb. and Bauhinia variegata L. are intermediate tolerant species. T. grandis had shown the highest dust-holding capacity (2.566 ± 0.0004 mg/cm2) whereas Albizia procera (0.018 ± 0.0002 mg/cm2) was found to be the lowest dust-holding capacity. Our findings also showed that the T. grandis and F. hispida have significant dust deposition with minimal effect of dust on their leaf chlorophyll (17.447 ± 0.019 mg/g and 14.703 ± 0.201 mg/g), protein (0.699 ± 0.001 mg/g and 0.604 ± 0.002 mg/g) and carotenoid (0.372 ± 0.003 mg/g and 0.354 ± 0.003 mg/g) content respectively among all selected plant species. Therefore, in the present investigation, plant species with high tolerance to high dust-holding capacity on their leaf surfaces are preferable for green corridors as open cast granite mines and their adjacent areas.
文摘Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost reduction.As most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and manufacturing.This paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and benefits.Factors affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and performance.Metallurgical analysis and mechanical property assessment of an ultra-large aluminum shape casting are presented.Challenges are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.