The esophagus is a tubular organ essential for maintaining normal eating function in humans.However,the replacement of the esophagus remains challenging in clinical settings.Although tissue engineering scaffolds are a...The esophagus is a tubular organ essential for maintaining normal eating function in humans.However,the replacement of the esophagus remains challenging in clinical settings.Although tissue engineering scaffolds are a promising alternative solution,their fabrication is difficult due to the complex structure and function of the esophagus.This review describes the existing fabrication methods for esophageal tubular scaffolds,including decellularization,casting,electrospinning,three dimensional(3 D)bioprinting,and pin-frogging.Also discussed are the stimulation cues of the fabricated esophageal tubular scaffold that induce esophageal muscle and epithelial cells.Finally,this review emphasizes three important concerns for esophageal tubular scaffolds:leakage and porosity,elasticity and proliferation of smooth muscle cells,and biocompatibility and structural fidelity of biomaterials.展开更多
Conventional fabrication methods lack the ability to control both macro- and micro-structures of generated scaffolds. Three-dimensional printing is a solid free-form fabrication method that provides novel ways to crea...Conventional fabrication methods lack the ability to control both macro- and micro-structures of generated scaffolds. Three-dimensional printing is a solid free-form fabrication method that provides novel ways to create customized scaffolds with high precision and accuracy. In this study, an electrically controlled cortical impactor was used to induce randomized brain tissue defects. The overall shape of scaffolds was designed using rat-specific anatomical data obtained from magnetic resonance imaging, and the internal structure was created by computer- aided design. As the result of limitations arising from insufficient resolution of the manufacturing process, we magnified the size of the cavity model prototype five-fold to successfully fabricate customized collagen-chitosan scaffolds using three-dimensional printing. Results demonstrated that scaffolds have three-dimensional porous structures, high porosity, highly specific surface areas, pore connectivity and good internal characteristics. Neural stem cells co-cultured with scaffolds showed good viability, indicating good biocompatibility and biodegradability. This technique may be a promising new strategy for regenerating complex damaged brain tissues, and helps pave the way toward personalized medicine.展开更多
-The necessity of using irregular waves, especially multi- directional waves to conduct three-dimensional model tests for port engineering and the test method are described in this paper through an example of model te...-The necessity of using irregular waves, especially multi- directional waves to conduct three-dimensional model tests for port engineering and the test method are described in this paper through an example of model test for a port. The test results show that a deep navigation channel has a large effect on the waves in front of the breakwater near the port entrance and on the wave condition in the port.展开更多
[Objective] The aim was to construct a virtuous eco-system covering multi-populations, multi-layers and multi-products and to explore timber production of physical and non-physical products, in order to extend product...[Objective] The aim was to construct a virtuous eco-system covering multi-populations, multi-layers and multi-products and to explore timber production of physical and non-physical products, in order to extend products operated in forestry engineering and seek a novel model for forestry engineering. [Method] A three-dimensional operation project was designed based on forestry lands in Bagua Zhou in Nanjing City. [Result] In the project, timber products, by-products in forest and relaxing products supplimented and supported each other, and a virtuous circle has been achieved. [Conclusion] The novel model makes simultaneous relaxing and working possible, which creat vaule together.展开更多
Any tidal defense engineering involves the collection and analysis of massive information about engineering structures and their surrounding environment. Traditional method, which is carried out mainly by means of two...Any tidal defense engineering involves the collection and analysis of massive information about engineering structures and their surrounding environment. Traditional method, which is carried out mainly by means of twodimensional drawings and textures, is not efficient and intuitive enough to analyze the whole project and reflect its spatial relationship. Three-dimensional visual simulation provides an advanced technical means of solving this problem. In this paper, triangular irregular network (TIN) model simplified by non-uniform rational B-splines (NURBS) technique was used to establish the digital terrain model (DTM) of a super large region. Simulation of dynamic water surface was realized by combining noise function with sine wave superposition method. Models of different objects were established with different modeling techniques according to their characteristics. Application of texture mapping technology remarkably improved the authenticity of the models. Taking the tidal defense engineering in the new coastal region of Tianjin as a case study, three-dimensional visual simulation and dynamic roaming of the study area were realized, providing visual analysis and visible demonstration method for the management and emergency decision-making associated with construction.展开更多
Three-dimensional models, consisting of the flame kernel formation model, flame kernel development model and natural gas single step reaction model, are used to analyze the contribution of cyclic equivalence ratio var...Three-dimensional models, consisting of the flame kernel formation model, flame kernel development model and natural gas single step reaction model, are used to analyze the contribution of cyclic equivalence ratio variations to cyclic variations in the compressed natural gas （CNG） lean burn spark ignition engine. Computational results including the contributions of equivalence ratio cyclic variations to each combustion stage and effects of engine speed to the extent of combustion variations are discussed. It is concluded that the equivalence ratio variations affect mostly the main stage of combustion and hardly influence initial kernel development stage.展开更多
Three-dimensional visualization technology converts engineering design drawings and data into graphics or images, realizes virtual reality perception of simulated users in future construction scene, enhances the inter...Three-dimensional visualization technology converts engineering design drawings and data into graphics or images, realizes virtual reality perception of simulated users in future construction scene, enhances the interaction between project management and technical personnel and engineering construction achievement, and provides intuitive, flexible and strong realistic experience for project management. It can effectively improve the level of project communication, and assist the needs of project construction planning management, training, exhibition, etc. As a tool to help improve project management skills, it has good application effect and prospects.展开更多
Oral and maxillofacial reconstruction represents one of the most complex challenges in plastic and reconstructive surgery,requiring the restoration of both form and function in highly specialized anatomical regions.Tr...Oral and maxillofacial reconstruction represents one of the most complex challenges in plastic and reconstructive surgery,requiring the restoration of both form and function in highly specialized anatomical regions.Traditional strategies,including local flaps and autologous bone grafts,remain fundamental but are limited by donor-site morbidity,tissue availability,and unpredictable outcomes.Recent advances in regenerative medicine have shifted the paradigm from repair to true regeneration,harnessing stem cells,biomaterial scaffolds,and signaling molecules in a synergistic approach.Dental-and craniofacial tissue-derived mesenchymal stem cells,along with adipose-derived stem cells,demonstrate significant potential for alveolar bone repair,periodontal regeneration,and soft tissue augmentation.Innovations in three-dimensional printing and bioactive matrices have enabled precise scaffold design and improved vascularization,thereby enhancing both predictability and esthetic outcomes.This mini review focuses on the synergistic role of stem cells,scaffolds,and signaling molecules in oral and maxillofacial regeneration,with an emphasis on the unique contributions of periodontists.By integrating periodontal biology with reconstructive techniques,a new collaborative framework is emerging to optimize regenerative outcomes.Future research must address clinical translation,large-scale trials,cost-effectiveness,and personalized approaches to fully realize the promise of regenerative surgery.展开更多
Articular cartilage damage caused by trauma or degenerative diseases such as osteoarthritis remains a major therapeutic challenge due to the tissue’s limited regenerative capacity.Traditional surgical interventions-i...Articular cartilage damage caused by trauma or degenerative diseases such as osteoarthritis remains a major therapeutic challenge due to the tissue’s limited regenerative capacity.Traditional surgical interventions-including microfracture,autologous chondrocyte implantation,and osteochondral grafting-often result in the formation of biomechanically inferior fibrocartilage and fail to restore longterm joint function.In contrast,stem cell-based strategies have emerged as a promising approach for regenerating hyaline-like cartilage by combining the biological potential of mesenchymal stem cells and induced pluripotent stem cells with advances in tissue engineering.This review synthesizes the current understanding of cartilage structure and repair limitations,evaluates the regenerative potential of various stem cell sources,and highlights engineering innovations such as bioactive scaffolds,controlled growth factor delivery,and threedimensional bioprinting.We also examine key preclinical studies and early-phase clinical trials demonstrating the safety and efficacy of stem cell-based therapies.Finally,we explore future directions,including gene editing,exosome-based therapeutics,and personalized regenerative strategies,that may address remaining translational barriers.Collectively,stem cell-centered approaches offer a transformative avenue toward durable,functional cartilage repair and hold strong potential for clinical application.展开更多
An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, clo...An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.展开更多
This paper presents the study of a three-dimensional(3D) isolation system.Firstly,the authors investigated the effects of an innovative 3D isolator,which was composed of a connecting plate,a rubber pad for vibration i...This paper presents the study of a three-dimensional(3D) isolation system.Firstly,the authors investigated the effects of an innovative 3D isolator,which was composed of a connecting plate,a rubber pad for vibration isolation in the vertical direction and a horizontal rubber bearing for seismic isolation in both horizontal directions.Secondly,the authors designed such a vibration isolation system and installed it underneath two specific residential buildings which were built directly over an existing subway communication hub platform in Beijing.These buildings required good performance vibration and seismic isolation system to reduce the impact from the running of nearby subway trains.Finally,in situ tests were conducted for both the isolated and the non-isolated buildings for the purpose of comparison.The test results showed that the maximum acceleration response level of the isolated superstructure is reduced by 10% as compared to that of the platform.The maximum attenuation of vibration reaches up to 25 dB.The 3D system explored in this paper is very effective in control and suppression of building vibration induced by earthquakes or running of trains.展开更多
To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test ...To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established.According to the relation of the dynamic seven photoelectric detection screen planes and the time values,the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.展开更多
To improve the combustion chamber shape that can decrease the directed injection （DI） diesel emission, the theories of DI diesel spray, combustion and pollutant formation model are analysed and implemented based on ...To improve the combustion chamber shape that can decrease the directed injection （DI） diesel emission, the theories of DI diesel spray, combustion and pollutant formation model are analysed and implemented based on the CFD code FIRE. Results show that the chamber with contracting orifice can get stronger squish swirl intensity. The results of the verification studies show a good accordance with the measurements and reveal that the individual processes of spray, evolution, combustion and pollutant formation are well captured in FIRE. Finally, based on the analyzing and comparing of the calculation results of different chambers, a combustion chamber of contracting orifice geometry with lower emission is proposed.展开更多
El-Ashmonein is a significant archaeological site with different buildings from various eras. Between the villages of El-Idara and El-Ashmonein are there mains of Hermopolis, one of the ancient Egyptian metropolis cap...El-Ashmonein is a significant archaeological site with different buildings from various eras. Between the villages of El-Idara and El-Ashmonein are there mains of Hermopolis, one of the ancient Egyptian metropolis capitals of the fifteenth century of Upper Egypt, called the hare. The buildings in this archaeological site are exposed to many causes of destruction and damage. The remaining structures and granite free standing columns in this area are suffered from plenty of geo-environmental and geotechnical problems. The main objectives of this study are 1) to assess the current state of preservation of this important archaeological site, especially the basilica church with its free standing huge columns, 2) to analyze the different actions which cause the destruction of the archaeological site, in particular the old flash floods and earthquakes, and 3) to identify the geochemical and engineering properties of the construction materials of the granitic columns and other limestone structures of the basilica church by using different kind of sophisticated analytical and diagnostic tools and methods. The multi-criteria analysis allowed the integration of several elements for mapping the vulnerable zones. Results revealed that about 80% of the study area was exposed to high and medium old floods vulnerability because of the vicinity to the Nile River. The structural and non-structural measures recommended in this research will help the decision makers and planners to effectively develop strategies for future site management, intervention retrofitting and rehabilitation of this unique archaeological site.展开更多
Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores 380-400μm in...Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores 380-400μm in diacneter spaced at intervals of 200μm. The layers of the linear penetration pores alternately lay perpendicular to pore direction. The porosity was 59%-65% . The Ca/ P molar ratios of the porous calcium phos phate ceramics range from 1.5 to 1.85. A binder cantaining methyl cellulose was most effective for preparing the powder compact among vinyl acetate, polyvinyl alcohol, starch, stearic acid, methyl cellulose and their mixtures . Stainless steel, polystyrene, nylon and bamboo were used as the long columnar dies for the penetrated open pores. When polystyrene, nylon and bamboo were used as the long columnar male dies, the dies were burned oat during the sintering process. Using stainless steel as the male dies with the removal of the dies before heat treatment resulted in a higher level of densification of the calcium phosphate ceramic.展开更多
Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. ...Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. It is usually difficult to obtaining solutions in connection with actual geological situations due to the ambiguity of the conventional gravity-processing results and lack of deep constraints. Thus, the three-dimensional (3D) inversion technology is considered as the main channel for reducing the number of solutions and improving the vertical resolution at the current stage. The current study starts from a model test and performs nonlinear 3D density-difference inversion called “model likelihood exploration”, which performs 3D inversion imaging and inversion of the known model while considering the topographic effects. The inversion results are highly consistent with those of the known models. Simultaneously, we consider the Beiya gold mine in Yunnan as an example. The nonlinear 3D densitydifference inversion technology, which is restricted by geological information, is explored to obtain the 3D density body structure below 5 km in the mine area, and the 3D structure of the deep and concealed rock masses are obtained using the density constraints of the intermediate-acid-complex rock masses. The results are well consistent with the surface geological masses and drilling-controlled deep geological masses. The model test and examples both show that the 3D density-difference nonlinear inversion technology can reduce inversion ambiguity, improve resolution, optimize the inversion results, and realize “transparency” in deeply concealed rock masses in ore-concentrated areas,which is useful in guiding the deep ore prospecting.展开更多
基金support from the National Natural Science Foundation of China(No.82472440)Hubei Provincial Natural Science Foundation of China(No.2023AFB141)+1 种基金the National Medical Products Administration Key Laboratory for Dental Materials(No.PKUSS20240401)the Cross-Research Support Program from Huazhong University of Science and Technology。
文摘The esophagus is a tubular organ essential for maintaining normal eating function in humans.However,the replacement of the esophagus remains challenging in clinical settings.Although tissue engineering scaffolds are a promising alternative solution,their fabrication is difficult due to the complex structure and function of the esophagus.This review describes the existing fabrication methods for esophageal tubular scaffolds,including decellularization,casting,electrospinning,three dimensional(3 D)bioprinting,and pin-frogging.Also discussed are the stimulation cues of the fabricated esophageal tubular scaffold that induce esophageal muscle and epithelial cells.Finally,this review emphasizes three important concerns for esophageal tubular scaffolds:leakage and porosity,elasticity and proliferation of smooth muscle cells,and biocompatibility and structural fidelity of biomaterials.
基金supported by the National Natural Science Foundation of China,No.81301050,81401067,81271392,81471275,81541034the Natural Science Foundation of Tianjin City of China,No.14JCQNJC10200,15JCQNJC11100,16JCYBJC27600
文摘Conventional fabrication methods lack the ability to control both macro- and micro-structures of generated scaffolds. Three-dimensional printing is a solid free-form fabrication method that provides novel ways to create customized scaffolds with high precision and accuracy. In this study, an electrically controlled cortical impactor was used to induce randomized brain tissue defects. The overall shape of scaffolds was designed using rat-specific anatomical data obtained from magnetic resonance imaging, and the internal structure was created by computer- aided design. As the result of limitations arising from insufficient resolution of the manufacturing process, we magnified the size of the cavity model prototype five-fold to successfully fabricate customized collagen-chitosan scaffolds using three-dimensional printing. Results demonstrated that scaffolds have three-dimensional porous structures, high porosity, highly specific surface areas, pore connectivity and good internal characteristics. Neural stem cells co-cultured with scaffolds showed good viability, indicating good biocompatibility and biodegradability. This technique may be a promising new strategy for regenerating complex damaged brain tissues, and helps pave the way toward personalized medicine.
文摘-The necessity of using irregular waves, especially multi- directional waves to conduct three-dimensional model tests for port engineering and the test method are described in this paper through an example of model test for a port. The test results show that a deep navigation channel has a large effect on the waves in front of the breakwater near the port entrance and on the wave condition in the port.
文摘[Objective] The aim was to construct a virtuous eco-system covering multi-populations, multi-layers and multi-products and to explore timber production of physical and non-physical products, in order to extend products operated in forestry engineering and seek a novel model for forestry engineering. [Method] A three-dimensional operation project was designed based on forestry lands in Bagua Zhou in Nanjing City. [Result] In the project, timber products, by-products in forest and relaxing products supplimented and supported each other, and a virtuous circle has been achieved. [Conclusion] The novel model makes simultaneous relaxing and working possible, which creat vaule together.
基金Supported by Tianjin Research Program of Application Foundation and Advanced Technology (No.12JCZDJC29200)Foundation for Innovative Research Groups of National Natural Science Foundation of China (No.51021004)National Key Technology R&D Program in the 12th Five-Year Plan of China(No.2011BAB10B06)
文摘Any tidal defense engineering involves the collection and analysis of massive information about engineering structures and their surrounding environment. Traditional method, which is carried out mainly by means of twodimensional drawings and textures, is not efficient and intuitive enough to analyze the whole project and reflect its spatial relationship. Three-dimensional visual simulation provides an advanced technical means of solving this problem. In this paper, triangular irregular network (TIN) model simplified by non-uniform rational B-splines (NURBS) technique was used to establish the digital terrain model (DTM) of a super large region. Simulation of dynamic water surface was realized by combining noise function with sine wave superposition method. Models of different objects were established with different modeling techniques according to their characteristics. Application of texture mapping technology remarkably improved the authenticity of the models. Taking the tidal defense engineering in the new coastal region of Tianjin as a case study, three-dimensional visual simulation and dynamic roaming of the study area were realized, providing visual analysis and visible demonstration method for the management and emergency decision-making associated with construction.
基金Sponsored by the National Natural Science Foundation of China(50406003)
文摘Three-dimensional models, consisting of the flame kernel formation model, flame kernel development model and natural gas single step reaction model, are used to analyze the contribution of cyclic equivalence ratio variations to cyclic variations in the compressed natural gas （CNG） lean burn spark ignition engine. Computational results including the contributions of equivalence ratio cyclic variations to each combustion stage and effects of engine speed to the extent of combustion variations are discussed. It is concluded that the equivalence ratio variations affect mostly the main stage of combustion and hardly influence initial kernel development stage.
文摘Three-dimensional visualization technology converts engineering design drawings and data into graphics or images, realizes virtual reality perception of simulated users in future construction scene, enhances the interaction between project management and technical personnel and engineering construction achievement, and provides intuitive, flexible and strong realistic experience for project management. It can effectively improve the level of project communication, and assist the needs of project construction planning management, training, exhibition, etc. As a tool to help improve project management skills, it has good application effect and prospects.
文摘Oral and maxillofacial reconstruction represents one of the most complex challenges in plastic and reconstructive surgery,requiring the restoration of both form and function in highly specialized anatomical regions.Traditional strategies,including local flaps and autologous bone grafts,remain fundamental but are limited by donor-site morbidity,tissue availability,and unpredictable outcomes.Recent advances in regenerative medicine have shifted the paradigm from repair to true regeneration,harnessing stem cells,biomaterial scaffolds,and signaling molecules in a synergistic approach.Dental-and craniofacial tissue-derived mesenchymal stem cells,along with adipose-derived stem cells,demonstrate significant potential for alveolar bone repair,periodontal regeneration,and soft tissue augmentation.Innovations in three-dimensional printing and bioactive matrices have enabled precise scaffold design and improved vascularization,thereby enhancing both predictability and esthetic outcomes.This mini review focuses on the synergistic role of stem cells,scaffolds,and signaling molecules in oral and maxillofacial regeneration,with an emphasis on the unique contributions of periodontists.By integrating periodontal biology with reconstructive techniques,a new collaborative framework is emerging to optimize regenerative outcomes.Future research must address clinical translation,large-scale trials,cost-effectiveness,and personalized approaches to fully realize the promise of regenerative surgery.
基金Supported by Yantai Science and Technology Innovation Development Plan Project,No.2023YD048.
文摘Articular cartilage damage caused by trauma or degenerative diseases such as osteoarthritis remains a major therapeutic challenge due to the tissue’s limited regenerative capacity.Traditional surgical interventions-including microfracture,autologous chondrocyte implantation,and osteochondral grafting-often result in the formation of biomechanically inferior fibrocartilage and fail to restore longterm joint function.In contrast,stem cell-based strategies have emerged as a promising approach for regenerating hyaline-like cartilage by combining the biological potential of mesenchymal stem cells and induced pluripotent stem cells with advances in tissue engineering.This review synthesizes the current understanding of cartilage structure and repair limitations,evaluates the regenerative potential of various stem cell sources,and highlights engineering innovations such as bioactive scaffolds,controlled growth factor delivery,and threedimensional bioprinting.We also examine key preclinical studies and early-phase clinical trials demonstrating the safety and efficacy of stem cell-based therapies.Finally,we explore future directions,including gene editing,exosome-based therapeutics,and personalized regenerative strategies,that may address remaining translational barriers.Collectively,stem cell-centered approaches offer a transformative avenue toward durable,functional cartilage repair and hold strong potential for clinical application.
基金Project(51274250)supported by the National Natural Science Foundation of ChinaProject(2012BAK09B02-05)supported by the National Key Technology R&D Program during the 12th Five-year Plan of China
文摘An integration processing system of three-dimensional laser scanning information visualization in goaf was developed. It is provided with multiple functions, such as laser scanning information management for goaf, cloud data de-noising optimization, construction, display and operation of three-dimensional model, model editing, profile generation, calculation of goaf volume and roof area, Boolean calculation among models and interaction with the third party soft ware. Concerning this system with a concise interface, plentiful data input/output interfaces, it is featured with high integration, simple and convenient operations of applications. According to practice, in addition to being well-adapted, this system is favorably reliable and stable.
基金Supported by the National Natural Science Foundation of China (Grant No. 51078098,90915007,90815027 and 50878124)the Key Laboratory of Seismic Control & Structure Safety Open FundInnovation Group Fund of Guangdong Province
文摘This paper presents the study of a three-dimensional(3D) isolation system.Firstly,the authors investigated the effects of an innovative 3D isolator,which was composed of a connecting plate,a rubber pad for vibration isolation in the vertical direction and a horizontal rubber bearing for seismic isolation in both horizontal directions.Secondly,the authors designed such a vibration isolation system and installed it underneath two specific residential buildings which were built directly over an existing subway communication hub platform in Beijing.These buildings required good performance vibration and seismic isolation system to reduce the impact from the running of nearby subway trains.Finally,in situ tests were conducted for both the isolated and the non-isolated buildings for the purpose of comparison.The test results showed that the maximum acceleration response level of the isolated superstructure is reduced by 10% as compared to that of the platform.The maximum attenuation of vibration reaches up to 25 dB.The 3D system explored in this paper is very effective in control and suppression of building vibration induced by earthquakes or running of trains.
基金supported by Project of the National Natural Science Foundation of China (No.62073256, 61773305)the Key Science and Technology Program of Shaanxi Province (No.2020GY-125)Xi’an Science and Technology Innovation talent service enterprise project (No.2020KJRC0041)。
文摘To objectively obtain the three-dimensional coordinates of the projectile fuze proximity explosion when projectile intersects the head of missile target, we propose a dynamic seven photoelectric detection screen test method, which is made up of six plane detection screens and a flash photoelectric dynamic detection screen. The three-dimensional coordinates calculation model of the projectile proximity explosion position based on seven plane detection screens with dynamic characteristics is established.According to the relation of the dynamic seven photoelectric detection screen planes and the time values,the analytical function of the projectile proximity explosion position parameters under non-linear motion is derived. The projectile signal filtering method based on discrete wavelet transform is explored in this work. Additionally, the projectile signal recognition algorithm using an improved particle swarm is proposed. Based on the characteristics of the time duration and the signal peak error for the projectile passing through the detection screen, the signals attribution of the same projectile passing through six detection screens are analyzed for obtaining precise time values of the same projectile passing through the detection screens. On the basis of the projectile fuze proximity explosion test, the linear motion model and the proposed non-linear motion model are used to calculate and compare the same group of projectiles proximity explosion position parameters. The comparison of test results verifies that the proposed test method and calculation model in this work accurately obtain the actual projectile proximity explosion position parameters.
文摘To improve the combustion chamber shape that can decrease the directed injection （DI） diesel emission, the theories of DI diesel spray, combustion and pollutant formation model are analysed and implemented based on the CFD code FIRE. Results show that the chamber with contracting orifice can get stronger squish swirl intensity. The results of the verification studies show a good accordance with the measurements and reveal that the individual processes of spray, evolution, combustion and pollutant formation are well captured in FIRE. Finally, based on the analyzing and comparing of the calculation results of different chambers, a combustion chamber of contracting orifice geometry with lower emission is proposed.
文摘El-Ashmonein is a significant archaeological site with different buildings from various eras. Between the villages of El-Idara and El-Ashmonein are there mains of Hermopolis, one of the ancient Egyptian metropolis capitals of the fifteenth century of Upper Egypt, called the hare. The buildings in this archaeological site are exposed to many causes of destruction and damage. The remaining structures and granite free standing columns in this area are suffered from plenty of geo-environmental and geotechnical problems. The main objectives of this study are 1) to assess the current state of preservation of this important archaeological site, especially the basilica church with its free standing huge columns, 2) to analyze the different actions which cause the destruction of the archaeological site, in particular the old flash floods and earthquakes, and 3) to identify the geochemical and engineering properties of the construction materials of the granitic columns and other limestone structures of the basilica church by using different kind of sophisticated analytical and diagnostic tools and methods. The multi-criteria analysis allowed the integration of several elements for mapping the vulnerable zones. Results revealed that about 80% of the study area was exposed to high and medium old floods vulnerability because of the vicinity to the Nile River. The structural and non-structural measures recommended in this research will help the decision makers and planners to effectively develop strategies for future site management, intervention retrofitting and rehabilitation of this unique archaeological site.
文摘Porous calcium phosphate ceramics were produced by compression molding using a special mold followed by sintering. The porous calcium phosphate ceramics have three-dimensional and penetrated open pores 380-400μm in diacneter spaced at intervals of 200μm. The layers of the linear penetration pores alternately lay perpendicular to pore direction. The porosity was 59%-65% . The Ca/ P molar ratios of the porous calcium phos phate ceramics range from 1.5 to 1.85. A binder cantaining methyl cellulose was most effective for preparing the powder compact among vinyl acetate, polyvinyl alcohol, starch, stearic acid, methyl cellulose and their mixtures . Stainless steel, polystyrene, nylon and bamboo were used as the long columnar dies for the penetrated open pores. When polystyrene, nylon and bamboo were used as the long columnar male dies, the dies were burned oat during the sintering process. Using stainless steel as the male dies with the removal of the dies before heat treatment resulted in a higher level of densification of the calcium phosphate ceramic.
基金The authors would like to thank the China Geological Survey (DD20190033)National Natural Science Foundation (41804144) for the financial support,Yunnan Gold and Mineral Group Co.,Ltd. for providing the original geological information,and the reviewers for providing valuable comments.
文摘Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. It is usually difficult to obtaining solutions in connection with actual geological situations due to the ambiguity of the conventional gravity-processing results and lack of deep constraints. Thus, the three-dimensional (3D) inversion technology is considered as the main channel for reducing the number of solutions and improving the vertical resolution at the current stage. The current study starts from a model test and performs nonlinear 3D density-difference inversion called “model likelihood exploration”, which performs 3D inversion imaging and inversion of the known model while considering the topographic effects. The inversion results are highly consistent with those of the known models. Simultaneously, we consider the Beiya gold mine in Yunnan as an example. The nonlinear 3D densitydifference inversion technology, which is restricted by geological information, is explored to obtain the 3D density body structure below 5 km in the mine area, and the 3D structure of the deep and concealed rock masses are obtained using the density constraints of the intermediate-acid-complex rock masses. The results are well consistent with the surface geological masses and drilling-controlled deep geological masses. The model test and examples both show that the 3D density-difference nonlinear inversion technology can reduce inversion ambiguity, improve resolution, optimize the inversion results, and realize “transparency” in deeply concealed rock masses in ore-concentrated areas,which is useful in guiding the deep ore prospecting.
