Since the discovery of graphene in 2004, two-dimensional (2D) materials have attracted worldwide interest. They are proved to be the most promising materials for next generation electronic and optoelectronic devices, ...Since the discovery of graphene in 2004, two-dimensional (2D) materials have attracted worldwide interest. They are proved to be the most promising materials for next generation electronic and optoelectronic devices, including transistor, photodetector, sensor, modulator and light-emitting diode. Defects, e.g. vacancies, adatoms, edges, grain boundaries, and substitutional impurities, are inevitable in 2D materials[1]. They will influence the performance of the materials in many aspects such as mechanical, electrical, optical and optoelectronic properties. For example, the presence of sulfur vacancies (SVs) leads to electron donor states within the electronic bandgap. This increases electron concentration and results in n-type characteristic in as-prepared MoS2. They could also give rise to hopping transport behavior in low carrier density and act as scattering centers to reduce the carrier mobility in MoS2. Thus, defect engineering, namely, eliminating the unfavorable defects and introducing beneficial defects is very meaningful, and would be a promising strategy to realize high performance electronic and optoelectronic devices based on 2D materials.展开更多
An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements o...An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the elements.It divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve chains.The parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid elements.The average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve chains.Through the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between them.The method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning system.The examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering drawings.The dimension information is complete,accurate and reliable.展开更多
Hydrogen(H2)is considered to be a promising substitute for fossil fuels.Two-dimensional(2D)nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly,...Hydrogen(H2)is considered to be a promising substitute for fossil fuels.Two-dimensional(2D)nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly,phase engineering of 2D nanomaterials is opening a novel research direction to endow 2D nanostructures with fascinating properties for deep applications in catalyzing HER.In this review,we briefly summarize the research progress and present the current challenges on phase engineering of 2D nanomaterials for their applications in electrocatalytic HER.Our summary will be of significance to provide fundamental understanding for designing novel 2D nanomaterials with unconventional phases to electrochemically catalyze HER.展开更多
Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins wi...Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins with three dimensional modeling that used computer instead of board. On the basis of target of teaching reform, set of teaching content, arrangement of class hour and teaching method, the research of teaching practice have been done, and very good effects in teaching of engineering drawing have been achieved.展开更多
A pioneering self-optimizing teaching method in student-centric seminars was introduced in this paper, in which each student will establish preferred engineering drawing process directed by educators and necessary pri...A pioneering self-optimizing teaching method in student-centric seminars was introduced in this paper, in which each student will establish preferred engineering drawing process directed by educators and necessary principles. We presented the working-memory centered mechanism in mental aspect to explain the phenomena. The theoretical mechanism is based on the typical translation between orthographic projection image and perspective image. The first is bonding object into a whole solid. The second is splicing the selected surfaces of objects and tailored them together. Two study groups were determined： an experimental group, who were directed to combine the object-based and surface-based construction methods in the presentations, and a control group, who learned through regular presentations made by an experienced teacher during the same period. The results showed that a significant enhancement in average scores has been achieved in the test among the experimental group in comparison with the control group. The variance of the scores is obviously reduced through the self-optimizing learning strategy, indicating a significant advantage on filling up the ability gaps among students. In fact, the results also indicated that the educator did keep the lesson in high quality. But it is worthy of more attention that the difference of mental manipulation habits between some students and educator may lead to a polarization in score distribution. So the seminar is a promising method to help the students to combine the object-based and surface-based construction methods.展开更多
Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of...Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of monolayer group-IV monochalcogenides MX(M=Sn,Ge;X=Se,Te,S)via strain engineering,and their effects with contaminated hydrogen are also discussed.GeSe,GeTe,and GeS do not go through transition up to the compressive strain of-5%,and consequently have good ferroelectric parameters for device applications that can be further improved by applying strain.According to the calculated ferroelectric properties and the band gaps of these materials,we find that their band gap can be adjusted by strain for excellent photovoltaic applications.In addition,we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe.It reveals that H prefers to absorb on SnS and SnTe monolayers as molecules rather than atomic H.As a result,hydrogen molecules have little effect on the polarization and electronic structure of monolayer SnTe and SnS.展开更多
Two-dimensional(2D)layered materials,including graphene,black phosphorus(BP)and transition metal dichalcogenide(TMD)such as molybdenum disulfide(Mo S2),tungsten diselenide(WSe2),have attracted increasing attention for...Two-dimensional(2D)layered materials,including graphene,black phosphorus(BP)and transition metal dichalcogenide(TMD)such as molybdenum disulfide(Mo S2),tungsten diselenide(WSe2),have attracted increasing attention for the application in electronic and optoelectronic devices.Contacts,which are the communication links between these 2D materials and external circuitry,have significant effects on the performance of electronic and optoelectronic devices.However,the performance of devices based on 2D semiconductors(SCs)is often limited by the contacts.Here,we provide a comprehensive overview of the basic physics and role of contacts in 2D SCs,elucidating Schottky barrier nature and Fermi level pinning effect at metal/2D SCs contact interface.The progress of contact engineering,including traditional metals contacts and metallic 2D materials contacts,for improving the performance of 2D SCs based devices is presented.Traditional metal contacts,named 3D top and edge contacts,are discussed briefly.Meanwhile,methods of building 2D materials contacts(2D top contact and 2D edge contact)are discussed in detail,such as chemical vapor deposition(CVD)growth of 2D metallic material contacts,phase engineered metallic phase contacts and intercalation induced metallic state contacts.Finally,the challenges and opportunities of contact engineering for 2D SCs are outlined.展开更多
Automatic recognition and interpretation of engineering drawing plays an important role in computer aided engineering. Detecting the positional relation between entities is an important topic in this research field. I...Automatic recognition and interpretation of engineering drawing plays an important role in computer aided engineering. Detecting the positional relation between entities is an important topic in this research field. In this paper the concepts of adjacent relativity and container window of drawing entities were proposed. By means of container window, the adjacent irrelative entities can be detected quickly and effectively, which speeds up the process of adjacent relativity detection. Meanwhile, the algorithm of adjacent relativity detection was discussed.展开更多
The course of architectural engineering drawing is the basic course before the students of civil engineering related majors study the professional courses.It aims to cultivate the students’ability of configuration,ex...The course of architectural engineering drawing is the basic course before the students of civil engineering related majors study the professional courses.It aims to cultivate the students’ability of configuration,expression,reading and drawing.BIM Technology simulates the real component information of a building through digital information simulation,and flexibly transforms between two-dimensional and threedimensional,providing a new tool for the teaching of architectural engineering drawing.This paper analyzes the characteristics of BIM Technology and teaching advantages,combined with the current teaching situation of architectural engineering drawing course,puts forward reform suggestions and implementation process,and provides reform ideas for the teaching of engineering basic courses.展开更多
The book ＂Selected Papers on Descriptive Geometry and Construction Drawing＂ was published by the joint efforts of three institutions （the Association for Science and Technology of Hubei Province, Hubei Province Car...The book ＂Selected Papers on Descriptive Geometry and Construction Drawing＂ was published by the joint efforts of three institutions （the Association for Science and Technology of Hubei Province, Hubei Province Cartographic Association, Hubei Science and Technology Information Institute） in 1965. It is the first collection of papers on construction drawing, representing the accomplishments of the research of the field in the 1960s in China. This paper describes its historical background, contents and val- He.展开更多
Recent development and recognition methods of raster to vector conversion for engineering drawings are presented. The advantages and disadvantages of all existing models are analyzed. Some research challenges and futu...Recent development and recognition methods of raster to vector conversion for engineering drawings are presented. The advantages and disadvantages of all existing models are analyzed. Some research challenges and future directions are discussed.展开更多
The design quality of construction drawing of building structure is an important basis of engineering construction quality, which can fully reflect the design concept. Any problems existing in the design of constructi...The design quality of construction drawing of building structure is an important basis of engineering construction quality, which can fully reflect the design concept. Any problems existing in the design of construction drawing will affect the safety of building. At the same time, the design of construction drawing has certain technical content, which reflects the architects grasp of the scheme and the ability to apply technology. Therefore, in order to conscientiously implement the relevant regulations of national architectural design and improve the design quality of structural construction drawings, this paper analyzes the problems existing in the design of structural construction drawings of architectural engineering, and puts forward some improvement suggestions for reference by structural construction drawing designers.展开更多
Engineering construction is a complex system engineering, the construction time is relatively long, the cost structure is relatively complex. Therefore, in the construction of the project, it is necessary to control t...Engineering construction is a complex system engineering, the construction time is relatively long, the cost structure is relatively complex. Therefore, in the construction of the project, it is necessary to control the project cost systematically, take reasonable and effective control measures, reduce the project cost, improve the control level of the project cost, and obtain good economic benefits. At the same time, the construction project budget cost control foundation and the accuracy of cost control can guarantee the good work in this respect. Analyze and expatiate the construction budget preparation method and the construction drawing related content, in order to strengthen the construction cost control, reduce the cost, and obtain good economic benefit.展开更多
The paper presents a promised way of feature recognition from 2D engineering drawing——developing special system and extracting features from machining drawings. In general, researchers inclined to extract features f...The paper presents a promised way of feature recognition from 2D engineering drawing——developing special system and extracting features from machining drawings. In general, researchers inclined to extract features from design drawings and ignored machining drawings. Actually, both of machining and design information shows the same importance in developing new products. Not only can machining drawing provide us with feature model or 3D geometrical model of the part, but also they can be easily recognized. In the paper the processes and methods of feature recognition from three-cone-bit (A Kind of aiguilles used to drill oil well) machining drawings are introduced. Firstly, overall approach is explained. Secondly, two methods of form feature recognition are introduced: symbol-matching method used to analyze annularity or chained graph and method based on feature-hint used to recognize the general features. Thirdly, feature parameters are extracted. Finally, a practical implementation is given.展开更多
The way of reform and development of Engineering Drawing education is explored. Such activities have been carried out for 5 years, and great progress in the update of course contents, teaching methods and other relate...The way of reform and development of Engineering Drawing education is explored. Such activities have been carried out for 5 years, and great progress in the update of course contents, teaching methods and other related aspects is achieved. A series of textbooks, multimedia CD and established a Web site for Engineering Drawing course have been published. The efforts to realize an advanced contemporary teaching mode are being made. With the support of multimedia software and resources over Internet, students become the real main body of study, the teaching qualities are supervised and controlled throughout, and the students?imagination and ability of design and drawing are greatly enhanced. All reform is built on digital technology.展开更多
Perovskite solar cells(PSCs)offer low costs and high power conversion efficiency.However,the lack of long-term stability,primarily stemming from the interfacial defects and the sus-ceptible metal electrodes,hinders th...Perovskite solar cells(PSCs)offer low costs and high power conversion efficiency.However,the lack of long-term stability,primarily stemming from the interfacial defects and the sus-ceptible metal electrodes,hinders their practical application.In the past few years,two-dimensional(2D)materials(e.g.,graphene and its derivatives,transitional metal dichalcogenides,MXenes,and black phosphorus)have been identified as a promising solution to solving these problems because of their dangling bond-free surfaces,layer-dependent electronic band structures,tunable functional groups,and inherent compactness.Here,recent progress of 2D material toward efficient and stable PSCs is summarized,including its role as both interface materials and electrodes.We discuss their beneficial effects on perovskite growth,energy level alignment,defect passivation,as well as blocking external stimulus.In particular,the unique properties of 2D materials to form van der Waals heterojunction at the bottom interface are emphasized.Finally,perspectives on the further development of PSCs using 2D materials are provided,such as designing high-quality van der Waals heterojunction,enhancing the uniformity and coverage of 2D nanosheets,and developing new 2D materials-based electrodes.展开更多
Strain engineering of two-dimensional(2D)material interfaces represents a powerful strategy for enhanc-ing the electrocatalytic activity of water splitting.However,maintaining catalytic stability under various harsh c...Strain engineering of two-dimensional(2D)material interfaces represents a powerful strategy for enhanc-ing the electrocatalytic activity of water splitting.However,maintaining catalytic stability under various harsh conditions by introducing interface strain remains a great challenge.The catalyst developed and evaluated herein comprised Ir clusters dispersed on 2D NiO nanosheets(NSs)derived from metal organic frameworks(lr@NiO/C_(BDc)),which displays a high activity and stability under all pH conditions,and even a change of only 1%in the applied voltage is observed after continuous electrocatalytic operation for over 1800 h under alkaline conditions.Through combined experimental and computational studies,we found that the introduced interfacial strain contributes to the outstanding structural stability of the Ir@NiO/CBDC catalyst,arising from its increased Ir and Ni vacancy formation energies,and hence suppressing its leach-ing.Moreover,strain also enhances the kinetically sluggish electrocatalytic water splitting reaction by op-timizing its electronic structure and coordination environment.This work highlights the effects of strain on catalyst stability and provides new insights for designing widely applicable electrocatalysts.展开更多
Two-dimensional(2D)materials have emerged as a significant class of materials promising for photocatalysis,and defect engineering offers an effective route for enhancing their photocatalytic performance.In this mini-r...Two-dimensional(2D)materials have emerged as a significant class of materials promising for photocatalysis,and defect engineering offers an effective route for enhancing their photocatalytic performance.In this mini-review,a first-principles design perspective on defect engineering in 2D materials for photocatalysis is provided.Various types of defects in 2D materials,spanning point,line,and planar defects are explored,and their influence on the intrinsic properties and photocatalytic efficacy of these materials is highlighted.Additionally,the use of theoretical descriptors to characterize the stability,electronic,optical,and catalytic properties of 2D defective systems is summarized.Central to the discussion is the understanding of electronic structure,optical properties,and reaction mechanisms to inform the rational design of photocatalysts based on 2D materials for enhanced photocatalytic performance.This mini-review aims to provide insights into the computational design of 2D defect systems tailored for efficient photocatalytic applications.展开更多
文摘Since the discovery of graphene in 2004, two-dimensional (2D) materials have attracted worldwide interest. They are proved to be the most promising materials for next generation electronic and optoelectronic devices, including transistor, photodetector, sensor, modulator and light-emitting diode. Defects, e.g. vacancies, adatoms, edges, grain boundaries, and substitutional impurities, are inevitable in 2D materials[1]. They will influence the performance of the materials in many aspects such as mechanical, electrical, optical and optoelectronic properties. For example, the presence of sulfur vacancies (SVs) leads to electron donor states within the electronic bandgap. This increases electron concentration and results in n-type characteristic in as-prepared MoS2. They could also give rise to hopping transport behavior in low carrier density and act as scattering centers to reduce the carrier mobility in MoS2. Thus, defect engineering, namely, eliminating the unfavorable defects and introducing beneficial defects is very meaningful, and would be a promising strategy to realize high performance electronic and optoelectronic devices based on 2D materials.
基金This work is supported by the Science and Technology Planning Project of Ronggui(grant number RGJF(2017)27H-8).
文摘An automated method based on the curve chain was proposed for dimensioning of engineering drawings for the mechanical products.According to the internal relation between the features of 3D model feature and elements of 2D drawing,the curve chain was established to reflect the geometric topological structure between the elements.It divides the dimensions into the absolute dimensions within the cure chain and the relative dimensions between the curve chains.The parallel and lengthy relationship between the drawing elements of the constructed X and Y parallel matrix was solved to remove redundant elements in the curve chain and labeled the absolute dimensions of the remaining valid elements.The average minimum weight coefficient was introduced to judge the dependence on the relative dimensions between curve chains.Through the analysis of the overlap between the circular rectangular areas,including all the absolute dimensions of the curve chains,overlapping curve chains were merged,and their dimensions were rearranged to avoid the cross interference between them.The method was seamlessly integrated into the drafting module of product design software NX,and it developed an automated dimensioning system.The examples show that the system has excellent interactivity and robustness in the dimensioning of product engineering drawings.The dimension information is complete,accurate and reliable.
基金financially supported by the Key Grant for Special Professors in Jiangsu Province(No.RK030STP18001)the Scientific Research Foundation of Nanjing University of Posts and Telecommunications(No.NY218150)“1311 Talents Program”of Nanjing University of Posts and Telecommunications and the National Postdoctoral Program for Innovative Talents(No.BX20190156)。
文摘Hydrogen(H2)is considered to be a promising substitute for fossil fuels.Two-dimensional(2D)nanomaterials have exhibited an efficient electrocatalytic capacity to catalyze hydrogen evolution reaction(HER).Particularly,phase engineering of 2D nanomaterials is opening a novel research direction to endow 2D nanostructures with fascinating properties for deep applications in catalyzing HER.In this review,we briefly summarize the research progress and present the current challenges on phase engineering of 2D nanomaterials for their applications in electrocatalytic HER.Our summary will be of significance to provide fundamental understanding for designing novel 2D nanomaterials with unconventional phases to electrochemically catalyze HER.
基金Supported by Beijing City Institution of Higher Learning Talent Education Program Project Foundation (PHR200906213PHR201007234)
文摘Based on the necessity of three dimensional modeling with computer in teaching reform, this paper is the summarization of reform practice of teaching engineering drawing in our institute. The teaching reform begins with three dimensional modeling that used computer instead of board. On the basis of target of teaching reform, set of teaching content, arrangement of class hour and teaching method, the research of teaching practice have been done, and very good effects in teaching of engineering drawing have been achieved.
基金Supported by the Teaching Demonstration Course Construction Project about Engineering Drawing of University of Science and Technology Beijing(KC2014YJX20)the Fundamental Research Funds for the Central Universities(FRF-BR-15-037A)
文摘A pioneering self-optimizing teaching method in student-centric seminars was introduced in this paper, in which each student will establish preferred engineering drawing process directed by educators and necessary principles. We presented the working-memory centered mechanism in mental aspect to explain the phenomena. The theoretical mechanism is based on the typical translation between orthographic projection image and perspective image. The first is bonding object into a whole solid. The second is splicing the selected surfaces of objects and tailored them together. Two study groups were determined： an experimental group, who were directed to combine the object-based and surface-based construction methods in the presentations, and a control group, who learned through regular presentations made by an experienced teacher during the same period. The results showed that a significant enhancement in average scores has been achieved in the test among the experimental group in comparison with the control group. The variance of the scores is obviously reduced through the self-optimizing learning strategy, indicating a significant advantage on filling up the ability gaps among students. In fact, the results also indicated that the educator did keep the lesson in high quality. But it is worthy of more attention that the difference of mental manipulation habits between some students and educator may lead to a polarization in score distribution. So the seminar is a promising method to help the students to combine the object-based and surface-based construction methods.
基金the National Natural Science Foundation of China(NSFC)(Grant No.12074126)the Foundation for Innovative Research Groups of NSFC(Grant No.51621001)the Fundamental Research Funds for the Central Universities(Grant No.2020ZYGXZR076).
文摘Two-dimensional(2D)ferroelectric compounds are a special class of materials that meet the need for devices miniaturization,which can lead to a wide range of applications.Here,we investigate ferroelectric properties of monolayer group-IV monochalcogenides MX(M=Sn,Ge;X=Se,Te,S)via strain engineering,and their effects with contaminated hydrogen are also discussed.GeSe,GeTe,and GeS do not go through transition up to the compressive strain of-5%,and consequently have good ferroelectric parameters for device applications that can be further improved by applying strain.According to the calculated ferroelectric properties and the band gaps of these materials,we find that their band gap can be adjusted by strain for excellent photovoltaic applications.In addition,we have determined the most stable hydrogen occupancy location in the monolayer SnS and SnTe.It reveals that H prefers to absorb on SnS and SnTe monolayers as molecules rather than atomic H.As a result,hydrogen molecules have little effect on the polarization and electronic structure of monolayer SnTe and SnS.
基金supported by the National Key R&D Program of China(Grant No.2018YFA0306900)the Natural Science Foundation of China(Grant No.51872012)。
文摘Two-dimensional(2D)layered materials,including graphene,black phosphorus(BP)and transition metal dichalcogenide(TMD)such as molybdenum disulfide(Mo S2),tungsten diselenide(WSe2),have attracted increasing attention for the application in electronic and optoelectronic devices.Contacts,which are the communication links between these 2D materials and external circuitry,have significant effects on the performance of electronic and optoelectronic devices.However,the performance of devices based on 2D semiconductors(SCs)is often limited by the contacts.Here,we provide a comprehensive overview of the basic physics and role of contacts in 2D SCs,elucidating Schottky barrier nature and Fermi level pinning effect at metal/2D SCs contact interface.The progress of contact engineering,including traditional metals contacts and metallic 2D materials contacts,for improving the performance of 2D SCs based devices is presented.Traditional metal contacts,named 3D top and edge contacts,are discussed briefly.Meanwhile,methods of building 2D materials contacts(2D top contact and 2D edge contact)are discussed in detail,such as chemical vapor deposition(CVD)growth of 2D metallic material contacts,phase engineered metallic phase contacts and intercalation induced metallic state contacts.Finally,the challenges and opportunities of contact engineering for 2D SCs are outlined.
文摘Automatic recognition and interpretation of engineering drawing plays an important role in computer aided engineering. Detecting the positional relation between entities is an important topic in this research field. In this paper the concepts of adjacent relativity and container window of drawing entities were proposed. By means of container window, the adjacent irrelative entities can be detected quickly and effectively, which speeds up the process of adjacent relativity detection. Meanwhile, the algorithm of adjacent relativity detection was discussed.
基金The general research project of higher education teaching reform of Heilongjiang Provincial Department of education in 2019“construction and application of Engineering Graphics Teaching System Based on OBE concept and BIM Technology”,subject No.sjgy20190540Ministry of education industry university cooperation collaborative education project(new engineering construction)“Research on the application of intelligent construction technology in the training of engineering cost professionals”,Project No.201902102001.
文摘The course of architectural engineering drawing is the basic course before the students of civil engineering related majors study the professional courses.It aims to cultivate the students’ability of configuration,expression,reading and drawing.BIM Technology simulates the real component information of a building through digital information simulation,and flexibly transforms between two-dimensional and threedimensional,providing a new tool for the teaching of architectural engineering drawing.This paper analyzes the characteristics of BIM Technology and teaching advantages,combined with the current teaching situation of architectural engineering drawing course,puts forward reform suggestions and implementation process,and provides reform ideas for the teaching of engineering basic courses.
文摘The book ＂Selected Papers on Descriptive Geometry and Construction Drawing＂ was published by the joint efforts of three institutions （the Association for Science and Technology of Hubei Province, Hubei Province Cartographic Association, Hubei Science and Technology Information Institute） in 1965. It is the first collection of papers on construction drawing, representing the accomplishments of the research of the field in the 1960s in China. This paper describes its historical background, contents and val- He.
文摘Recent development and recognition methods of raster to vector conversion for engineering drawings are presented. The advantages and disadvantages of all existing models are analyzed. Some research challenges and future directions are discussed.
文摘The design quality of construction drawing of building structure is an important basis of engineering construction quality, which can fully reflect the design concept. Any problems existing in the design of construction drawing will affect the safety of building. At the same time, the design of construction drawing has certain technical content, which reflects the architects grasp of the scheme and the ability to apply technology. Therefore, in order to conscientiously implement the relevant regulations of national architectural design and improve the design quality of structural construction drawings, this paper analyzes the problems existing in the design of structural construction drawings of architectural engineering, and puts forward some improvement suggestions for reference by structural construction drawing designers.
文摘Engineering construction is a complex system engineering, the construction time is relatively long, the cost structure is relatively complex. Therefore, in the construction of the project, it is necessary to control the project cost systematically, take reasonable and effective control measures, reduce the project cost, improve the control level of the project cost, and obtain good economic benefits. At the same time, the construction project budget cost control foundation and the accuracy of cost control can guarantee the good work in this respect. Analyze and expatiate the construction budget preparation method and the construction drawing related content, in order to strengthen the construction cost control, reduce the cost, and obtain good economic benefit.
文摘The paper presents a promised way of feature recognition from 2D engineering drawing——developing special system and extracting features from machining drawings. In general, researchers inclined to extract features from design drawings and ignored machining drawings. Actually, both of machining and design information shows the same importance in developing new products. Not only can machining drawing provide us with feature model or 3D geometrical model of the part, but also they can be easily recognized. In the paper the processes and methods of feature recognition from three-cone-bit (A Kind of aiguilles used to drill oil well) machining drawings are introduced. Firstly, overall approach is explained. Secondly, two methods of form feature recognition are introduced: symbol-matching method used to analyze annularity or chained graph and method based on feature-hint used to recognize the general features. Thirdly, feature parameters are extracted. Finally, a practical implementation is given.
文摘The way of reform and development of Engineering Drawing education is explored. Such activities have been carried out for 5 years, and great progress in the update of course contents, teaching methods and other related aspects is achieved. A series of textbooks, multimedia CD and established a Web site for Engineering Drawing course have been published. The efforts to realize an advanced contemporary teaching mode are being made. With the support of multimedia software and resources over Internet, students become the real main body of study, the teaching qualities are supervised and controlled throughout, and the students?imagination and ability of design and drawing are greatly enhanced. All reform is built on digital technology.
基金the financial support of the National Natural Science Foundation of China(Nos.U21A20171,12074245,and 52102281)National Key R&D Program of China(Nos.2021YFB3800068 and 2020YFB1506400)+1 种基金Shanghai Sailing Program(No.21YF1421600)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(No.2021QNRC001).
文摘Perovskite solar cells(PSCs)offer low costs and high power conversion efficiency.However,the lack of long-term stability,primarily stemming from the interfacial defects and the sus-ceptible metal electrodes,hinders their practical application.In the past few years,two-dimensional(2D)materials(e.g.,graphene and its derivatives,transitional metal dichalcogenides,MXenes,and black phosphorus)have been identified as a promising solution to solving these problems because of their dangling bond-free surfaces,layer-dependent electronic band structures,tunable functional groups,and inherent compactness.Here,recent progress of 2D material toward efficient and stable PSCs is summarized,including its role as both interface materials and electrodes.We discuss their beneficial effects on perovskite growth,energy level alignment,defect passivation,as well as blocking external stimulus.In particular,the unique properties of 2D materials to form van der Waals heterojunction at the bottom interface are emphasized.Finally,perspectives on the further development of PSCs using 2D materials are provided,such as designing high-quality van der Waals heterojunction,enhancing the uniformity and coverage of 2D nanosheets,and developing new 2D materials-based electrodes.
基金Hainan Province Science and Technology Special Fund(Nos.ZDYF2021SHFZ068 and ZDKJ2021029)National Natural Science Foundation of China(No.52262014)+1 种基金Hainan Provincial Natural Science Foundation of China(No.823CXTD376)Youth Foundation of Hainan Province(No.221QN0898).
文摘Strain engineering of two-dimensional(2D)material interfaces represents a powerful strategy for enhanc-ing the electrocatalytic activity of water splitting.However,maintaining catalytic stability under various harsh conditions by introducing interface strain remains a great challenge.The catalyst developed and evaluated herein comprised Ir clusters dispersed on 2D NiO nanosheets(NSs)derived from metal organic frameworks(lr@NiO/C_(BDc)),which displays a high activity and stability under all pH conditions,and even a change of only 1%in the applied voltage is observed after continuous electrocatalytic operation for over 1800 h under alkaline conditions.Through combined experimental and computational studies,we found that the introduced interfacial strain contributes to the outstanding structural stability of the Ir@NiO/CBDC catalyst,arising from its increased Ir and Ni vacancy formation energies,and hence suppressing its leach-ing.Moreover,strain also enhances the kinetically sluggish electrocatalytic water splitting reaction by op-timizing its electronic structure and coordination environment.This work highlights the effects of strain on catalyst stability and provides new insights for designing widely applicable electrocatalysts.
文摘Two-dimensional(2D)materials have emerged as a significant class of materials promising for photocatalysis,and defect engineering offers an effective route for enhancing their photocatalytic performance.In this mini-review,a first-principles design perspective on defect engineering in 2D materials for photocatalysis is provided.Various types of defects in 2D materials,spanning point,line,and planar defects are explored,and their influence on the intrinsic properties and photocatalytic efficacy of these materials is highlighted.Additionally,the use of theoretical descriptors to characterize the stability,electronic,optical,and catalytic properties of 2D defective systems is summarized.Central to the discussion is the understanding of electronic structure,optical properties,and reaction mechanisms to inform the rational design of photocatalysts based on 2D materials for enhanced photocatalytic performance.This mini-review aims to provide insights into the computational design of 2D defect systems tailored for efficient photocatalytic applications.
