Transportation plays a critical role in the economic sector in Bangladesh.Since its independence,infrastructure has been developing rapidly,includ-ing land,water,and air transportation.National economy is increasing a...Transportation plays a critical role in the economic sector in Bangladesh.Since its independence,infrastructure has been developing rapidly,includ-ing land,water,and air transportation.National economy is increasing at a relatively high rate,leading to the better-off of people’s lives.As the living standards keep improving,people are more concerned about safety issues in transportation.This article makes an analysis of the status quo of traffic safety in Bangladesh and compares the Bangladeshi code with American code AASHTO from the geometric aspects of horizontal and vertical align-ment,in an effort to provide reference to the highway design in Bangla-desh.Through a reasonable design,the traffic safety will be under control and accident rate as well as economic loss will be minimized.展开更多
Abstract For two rational quadratic B spline curves with same control vertexes, the cross ratio of four collinear points are represented: which are any one of the vertexes, and the two points that the ray initialing f...Abstract For two rational quadratic B spline curves with same control vertexes, the cross ratio of four collinear points are represented: which are any one of the vertexes, and the two points that the ray initialing from the vertex intersects with the corresponding segments of the two curves, and the point the ray intersecting with the connecting line between the two neighboring vertexes. Different from rational quadratic Bézier curves, the value is generally related with the location of the ray, and the necessary and sufficient condition of the ratio being independent of the ray's location is showed. Also another cross ratio of the following four collinear points are suggested, i.e. one vertex, the points that the ray from the initial vertex intersects respectively with the curve segment, the line connecting the segments end points, and the line connecting the two neighboring vertexes. This cross ratio is concerned only with the ray's location, but not with the weights of the curve. Furthermore, the cross ratio is projective invariant under the projective transformation between the two segments.展开更多
Smoothly stitching multiple surfaces mainly represented by B-spline or NURBS together is an extremely important issue in complex surfaces modeling and reverse engineering. In recent years, a lot of progress has been m...Smoothly stitching multiple surfaces mainly represented by B-spline or NURBS together is an extremely important issue in complex surfaces modeling and reverse engineering. In recent years, a lot of progress has been made in smooth join of non-trimmed surface patches, while there has been seldom research on smoothly stitching trimmed surface patches together. This paper studies the problem of global continuity adjustment, damaged hole repair and local shape optimization for complex trimmed surface model, and presents a uniform scheme to deal with continuity adjustment of trimmed surfaces and geometric repair of local broken region. Constrained B-spline surface refitting technique and trim calculation are first utilized to achieve global G^1 continuity, and then local shape optimization functional is adopted to reduce fitting error and improve local quality of refitted surface patch. The proposed approach is applied to a discontinuity ship hull surface model with an irregular hole, and the result demonstrates the validation of our method. Furthermore, on the premise of global continuity, the proposed locally repairing damaged surface model provides a better foundation for following research work, such as topology recovery technique for complex surface model after geometric repair.展开更多
Applying the distance function between two B-spline curves with respect to the L2 norm as the approximate error, we investigate the problem of approximate merging of two adjacent B-spline curves into one B-spline curv...Applying the distance function between two B-spline curves with respect to the L2 norm as the approximate error, we investigate the problem of approximate merging of two adjacent B-spline curves into one B-spline curve. Then this method can be easily extended to the approximate merging problem of multiple B-spline curves and of two adjacent surfaces. After minimizing the approximate error between curves or surfaces, the approximate merging problem can be transformed into equations solving. We express both the new control points and the precise error of approximation explicitly in matrix form. Based on homogeneous coordinates and quadratic programming, we also introduce a new framework for approximate merging of two adjacent NURBS curves. Finally, several numerical examples demonstrate the effectiveness and validity of the algorithm.展开更多
Optoelectronic imaging equipment is easy to expose to active laser detection devices because of "cat eye" effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a ...Optoelectronic imaging equipment is easy to expose to active laser detection devices because of "cat eye" effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.展开更多
In this paper, the smooth connection between two B-spline surfaces is discussed. First, a brief proof of some simple sufficient conditions of Go and G1 continuity is given. On this basis, a novel method for Go or G1 c...In this paper, the smooth connection between two B-spline surfaces is discussed. First, a brief proof of some simple sufficient conditions of Go and G1 continuity is given. On this basis, a novel method for Go or G1 connection between two adjacent B-spline surfaces is presented. A reparameterization step is firstly taken for one of the surfaces such that they have the same parameterization in v direction, then, adjust their boundary control vertices to make them Go or Gl connected. The GI connection parameter is determined by an optimization problem. Compared with the existed methods, our method is simple and easy to be used in practice.展开更多
A collaborative virtual modeling environment based on VRML is presented as a sugarcane harvester modeling framework, and is illustrated with the implemented software that can using I;EAS, Smarteam, and Conceptual Inno...A collaborative virtual modeling environment based on VRML is presented as a sugarcane harvester modeling framework, and is illustrated with the implemented software that can using I;EAS, Smarteam, and Conceptual Innovation Design System (CIDS) as the supporting platform, which is powerful enough to meet the demands of different real life applications. It is possible to perform collaborative interactive modifications with concurrent synchronous visualization at each client computer with any required level of detail. The platform provides a product modeling and assembling environment, and the product data among I;EAS, Smarteam and CIDS can be exchanged.展开更多
A Bezier interpolation approach is proposed which uses local generation of endpoint slopes and forces the curve and the surface to pass through an arbitrarily specified point to control and modify the shape of curve a...A Bezier interpolation approach is proposed which uses local generation of endpoint slopes and forces the curve and the surface to pass through an arbitrarily specified point to control and modify the shape of curve and surface, making the result satisfactory.展开更多
This paper proposes a new computer aided pattern design system(CAPDS)in which a uniformmathematical expression is used to construct different objects. In the geometric model, 3 B-splineis adopted as a line model. The ...This paper proposes a new computer aided pattern design system(CAPDS)in which a uniformmathematical expression is used to construct different objects. In the geometric model, 3 B-splineis adopted as a line model. The new system with uniform mathematical expression has the distin-guishing features: curve smoothness and fidelity, convenience to process graphic data in thedatabase and etc.. This paper presents the data structure, the program structure and also the implementation.展开更多
Parking automation has been developed for locating available parking spaces inside a parking lot with new technologies, such as automatic collection, capacity, or empty spaces’ detection;to both reduce search time an...Parking automation has been developed for locating available parking spaces inside a parking lot with new technologies, such as automatic collection, capacity, or empty spaces’ detection;to both reduce search time and avoid crowds of vehicles waiting to park in it. A simple detection system of available spaces, within the Faculty and Staff parking lot of the Engineering and Chemistry Departments at the Autonomous University of Chihuahua, Mexico (UACH), was set up. First, an analysis of vehicle capacity was carried out to establish the peak hours of vehicles’ entrance</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> and compar</span><span style="font-family:Verdana;">e</span><span style="font-family:Verdana;"> it to the parking lots’ capacity. For one working week (6 days), it was determined that Tuesdays have the highest vehicle occupancy, and Saturdays are the days with the least traffic. Second, the geometric design of the parking lot (divided in</span><span style="font-family:Verdana;">to</span><span style="font-family:Verdana;"> two areas because of the terrain topography: upper and bottom levels), its dimensions and location of parking spots and marks on the pavement for traffic directions, were obtained from its blueprint, to visualize how the surveillance cameras can be oriented to cover the area. A detection system prototype was created for a specific area of the parking lot, using an artificial vision technique to perform the video extraction, while the digital image processing was developed in MATLAB. To complement and achieve the objective, Object-</span><span style="font-family:""> </span><span style="font-family:Verdana;">Oriented Programming (OOP) was used to obtain the count analysis as well as the availability/occupancy of each of the parking areas. This information is shown </span><span style="font-family:Verdana;">o</span><span style="font-family:Verdana;">n a web page, with a simple driver-friendly design, since it has each parking space number and its availability in blue with the word “Available” or, in the opposite case, the word “Taken” in pink.展开更多
The presented work will show the highest relevance of solving all the issues related to this problem and present the results of the analysis of the main expected potential problems,which may occur in the implementatio...The presented work will show the highest relevance of solving all the issues related to this problem and present the results of the analysis of the main expected potential problems,which may occur in the implementation of the INDUSTRY-4.0 reform.It is proved that the pace and level of development of this reform will be determined to a large extent by the effectiveness of the individual nodes used and the entire mechatronic system.It has also been established that as a result of systematic miniaturization of the nodes of radio-electronic equipment and microelectronic equipment and microelectronic technology,the main problem of these reforms and the implementation of complex technological processes is instrumental and technological support,especially with cutting micro-tools and equipment.Therefore,on the example of these investigations,methods for improving their performance are shown.展开更多
A novel method to extract conic blending feature in reverse engineering is presented. Different from the methods to recover constant and variable radius blends from unorganized points, it contains not only novel segme...A novel method to extract conic blending feature in reverse engineering is presented. Different from the methods to recover constant and variable radius blends from unorganized points, it contains not only novel segmentation and feature recognition techniques, but also bias corrected technique to capture more reliable distribution of feature parameters along the spine curve. The segmentation depending on point classification separates the points in the conic blend region from the input point cloud. The available feature parameters of the cross-sectional curves are extracted with the processes of slicing point clouds with planes, conic curve fitting, and parameters estimation and compensation, The extracted parameters and its distribution laws are refined according to statistic theory such as regression analysis and hypothesis test. The proposed method can accurately capture the original design intentions and conveniently guide the reverse modeling process. Application examples are presented to verify the high precision and stability of the proposed method.展开更多
A method to reparametrize G retional curve to obtain a C^1 curve is given. A practical G^1 continual connective between adjacent NURUS patches along common guadratic boundary curve is presented in this paper, and a s...A method to reparametrize G retional curve to obtain a C^1 curve is given. A practical G^1 continual connective between adjacent NURUS patches along common guadratic boundary curve is presented in this paper, and a specific algorithm for control points and weights of NURBS patches is discussed.展开更多
Constructing Bernstein-Bezier triangular interpolating curve surface interpolating a series of arbitrary disordered data points is of considerable importance for the design and modeling of surfaces with a variety of c...Constructing Bernstein-Bezier triangular interpolating curve surface interpolating a series of arbitrary disordered data points is of considerable importance for the design and modeling of surfaces with a variety of continuity information. In this article. a kind of simple and reliable algorithm that can process complex field triangular grid generating is presented, and a group of formulae for determining triangular curved surface with wholly C1 continuity are given. It can process arbitrary non-convex boundary and can be used to construct surfaces inner holes.展开更多
Using Galois rings and Galois fields, we construct several infinite classes of partial geometric difference sets, and partial geometric difference families, with new parameters. Furthermore, these partial geometric di...Using Galois rings and Galois fields, we construct several infinite classes of partial geometric difference sets, and partial geometric difference families, with new parameters. Furthermore, these partial geometric difference sets(and partial geometric difference families) correspond to new infinite families of directed strongly regular graphs. We also discuss some of the links between partially balanced designs, 2-adesigns(which were recently coined by Cunsheng Ding in "Codes from Difference Sets"(2015)), and partial geometric designs, and make an investigation into when a 2-adesign is a partial geometric design.展开更多
This paper focuses on analysing the influence of geometric design characteristics on traffic safety using bi-directional data on a divided roadway operated under heterogeneous traffic conditions in India. The study wa...This paper focuses on analysing the influence of geometric design characteristics on traffic safety using bi-directional data on a divided roadway operated under heterogeneous traffic conditions in India. The study was carried out on a four lane divided inter-city highway in plain and rolling terrain. Statistical modelling approach by Poisson regression and Negative binomial regression were used to assess the safety performance as occurrence of crashes are random events and to identify the influence of the geometric design variables on the crash frequency. Negative binomial regression model was found to be more suitable to identify the variables contributing to road crashes. The study enabled better understanding of the factors related to road geometrics that influence road crash frequency. The study also established that operating speed has a significant contribution to the total number of crashes. Negative binomial models are found to be appropriate to predict road crashes on divided roadways under heterogeneous traffic conditions.展开更多
As the fourth-generation light source,solid-state lighting has developed rapidly in the past 30 years due to its advantages of high efficiency and environmental protection.It is widely used in various scenes such as a...As the fourth-generation light source,solid-state lighting has developed rapidly in the past 30 years due to its advantages of high efficiency and environmental protection.It is widely used in various scenes such as automobile headlights,projection displays,industrial production,and remote lighting.High-power,high-brightness white light-emitting diodes(LEDs)and laser diodes(LDs)technology put forward new requirements for the service stability of color conversion materials.Garnet phosphor ceramics have emerged with their unique advantages of withstanding high power excitation density and the flexibly tunable spectrum.In this article,the research progress of garnet based phosphor ceramics for high-power solid-state lighting was comprehensively reviewed.Firstly,the band gap and coordination environment regulations of luminescence centers of garnet phosphor were summarized.Secondly,the improvement of luminous efficacy via defects regulation was discussed.Thirdly,the relationship between the geometric design and the lighting performance was elucidated.Fourthly,the characterization methods of phosphor ceramics for laser lighting were introduced and illustrated.Finally,the development trend of garnet phosphor ceramics in solid state lighting and display was prospected.展开更多
In computer aided geometric design(CAGD),the Bernstein-Bézier system for polynomial space including the triangular domain is an important tool for modeling free form shapes.The Bernstein-like bases for other spac...In computer aided geometric design(CAGD),the Bernstein-Bézier system for polynomial space including the triangular domain is an important tool for modeling free form shapes.The Bernstein-like bases for other spaces(trigonometric polynomial,hyperbolic polynomial,or blended space) has also been studied.However,none of them was extended to the triangular domain.In this paper,we extend the linear trigonometric polynomial basis to the triangular domain and obtain a new Bernstein-like basis,which is linearly independent and satisfies positivity,partition of unity,symmetry,and boundary represen-tation.We prove some properties of the corresponding surfaces,including differentiation,subdivision,convex hull,and so forth.Some applications are shown.展开更多
Non-uniform rational B-spline (NURBS) curves and surfaces are very important tools for model- ling curves and surfaces. Several important details, such as the choice of the sample points, of the parame- terization, an...Non-uniform rational B-spline (NURBS) curves and surfaces are very important tools for model- ling curves and surfaces. Several important details, such as the choice of the sample points, of the parame- terization, and of the termination condition, are however not well described. These details have a great in- fluence on the performance of the approximation algorithm, both in terms of quality as well as time and space usage. This paper described how to sample points, examining two standard parameterizations: equi- distant and chordal. A new and local parameterization, namely an adaptive equidistant model, was pro- posed, which enhances the equidistant model. Localization can also be used to enhance the chordal parameterization. For NURBS surfaces, one must choose which direction will be approximated first and must pay special attention to surfaces of degree 1 which have to be handled as a special case.展开更多
文摘Transportation plays a critical role in the economic sector in Bangladesh.Since its independence,infrastructure has been developing rapidly,includ-ing land,water,and air transportation.National economy is increasing at a relatively high rate,leading to the better-off of people’s lives.As the living standards keep improving,people are more concerned about safety issues in transportation.This article makes an analysis of the status quo of traffic safety in Bangladesh and compares the Bangladeshi code with American code AASHTO from the geometric aspects of horizontal and vertical align-ment,in an effort to provide reference to the highway design in Bangla-desh.Through a reasonable design,the traffic safety will be under control and accident rate as well as economic loss will be minimized.
文摘Abstract For two rational quadratic B spline curves with same control vertexes, the cross ratio of four collinear points are represented: which are any one of the vertexes, and the two points that the ray initialing from the vertex intersects with the corresponding segments of the two curves, and the point the ray intersecting with the connecting line between the two neighboring vertexes. Different from rational quadratic Bézier curves, the value is generally related with the location of the ray, and the necessary and sufficient condition of the ratio being independent of the ray's location is showed. Also another cross ratio of the following four collinear points are suggested, i.e. one vertex, the points that the ray from the initial vertex intersects respectively with the curve segment, the line connecting the segments end points, and the line connecting the two neighboring vertexes. This cross ratio is concerned only with the ray's location, but not with the weights of the curve. Furthermore, the cross ratio is projective invariant under the projective transformation between the two segments.
基金supported by National Natural Science Foundation of China (Grant No.50575098)
文摘Smoothly stitching multiple surfaces mainly represented by B-spline or NURBS together is an extremely important issue in complex surfaces modeling and reverse engineering. In recent years, a lot of progress has been made in smooth join of non-trimmed surface patches, while there has been seldom research on smoothly stitching trimmed surface patches together. This paper studies the problem of global continuity adjustment, damaged hole repair and local shape optimization for complex trimmed surface model, and presents a uniform scheme to deal with continuity adjustment of trimmed surfaces and geometric repair of local broken region. Constrained B-spline surface refitting technique and trim calculation are first utilized to achieve global G^1 continuity, and then local shape optimization functional is adopted to reduce fitting error and improve local quality of refitted surface patch. The proposed approach is applied to a discontinuity ship hull surface model with an irregular hole, and the result demonstrates the validation of our method. Furthermore, on the premise of global continuity, the proposed locally repairing damaged surface model provides a better foundation for following research work, such as topology recovery technique for complex surface model after geometric repair.
基金Supported by the National Natural Science Foundation of China (60873111, 60933007)
文摘Applying the distance function between two B-spline curves with respect to the L2 norm as the approximate error, we investigate the problem of approximate merging of two adjacent B-spline curves into one B-spline curve. Then this method can be easily extended to the approximate merging problem of multiple B-spline curves and of two adjacent surfaces. After minimizing the approximate error between curves or surfaces, the approximate merging problem can be transformed into equations solving. We express both the new control points and the precise error of approximation explicitly in matrix form. Based on homogeneous coordinates and quadratic programming, we also introduce a new framework for approximate merging of two adjacent NURBS curves. Finally, several numerical examples demonstrate the effectiveness and validity of the algorithm.
基金Project supported by the National Natural Science Foundation of China(Grant No.61471039)
文摘Optoelectronic imaging equipment is easy to expose to active laser detection devices because of "cat eye" effect. In this paper, we propose a new structure of optical system to reduce the retroreflector effect of a cat eye target. Decentered field lens structure is adopted in the design without sacrificing imaging quality and clear aperture. An imaging system with±30° field of view is taken for example. The detailed design and simulation results are presented. The results indicate that this kind of optical system can reduce the retroreflection signal substantially and maintain acceptable imaging performance.
基金Supported by the Natural Science Foundation of Hebei Province(No.F2012202041)Youth Research Foundation of Science and Technology of Hebei Education Departmen(No.Q2012022)
文摘In this paper, the smooth connection between two B-spline surfaces is discussed. First, a brief proof of some simple sufficient conditions of Go and G1 continuity is given. On this basis, a novel method for Go or G1 connection between two adjacent B-spline surfaces is presented. A reparameterization step is firstly taken for one of the surfaces such that they have the same parameterization in v direction, then, adjust their boundary control vertices to make them Go or Gl connected. The GI connection parameter is determined by an optimization problem. Compared with the existed methods, our method is simple and easy to be used in practice.
基金Supported by National Science and Technology Support Plan (2008BAH22B02)national natural science foundation of China (Grand No. 60573147 and No. 60173035) 863 High Tech Project of China (Grant No. 2003AA411310)
文摘A collaborative virtual modeling environment based on VRML is presented as a sugarcane harvester modeling framework, and is illustrated with the implemented software that can using I;EAS, Smarteam, and Conceptual Innovation Design System (CIDS) as the supporting platform, which is powerful enough to meet the demands of different real life applications. It is possible to perform collaborative interactive modifications with concurrent synchronous visualization at each client computer with any required level of detail. The platform provides a product modeling and assembling environment, and the product data among I;EAS, Smarteam and CIDS can be exchanged.
文摘A Bezier interpolation approach is proposed which uses local generation of endpoint slopes and forces the curve and the surface to pass through an arbitrarily specified point to control and modify the shape of curve and surface, making the result satisfactory.
文摘This paper proposes a new computer aided pattern design system(CAPDS)in which a uniformmathematical expression is used to construct different objects. In the geometric model, 3 B-splineis adopted as a line model. The new system with uniform mathematical expression has the distin-guishing features: curve smoothness and fidelity, convenience to process graphic data in thedatabase and etc.. This paper presents the data structure, the program structure and also the implementation.
文摘Parking automation has been developed for locating available parking spaces inside a parking lot with new technologies, such as automatic collection, capacity, or empty spaces’ detection;to both reduce search time and avoid crowds of vehicles waiting to park in it. A simple detection system of available spaces, within the Faculty and Staff parking lot of the Engineering and Chemistry Departments at the Autonomous University of Chihuahua, Mexico (UACH), was set up. First, an analysis of vehicle capacity was carried out to establish the peak hours of vehicles’ entrance</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;"> and compar</span><span style="font-family:Verdana;">e</span><span style="font-family:Verdana;"> it to the parking lots’ capacity. For one working week (6 days), it was determined that Tuesdays have the highest vehicle occupancy, and Saturdays are the days with the least traffic. Second, the geometric design of the parking lot (divided in</span><span style="font-family:Verdana;">to</span><span style="font-family:Verdana;"> two areas because of the terrain topography: upper and bottom levels), its dimensions and location of parking spots and marks on the pavement for traffic directions, were obtained from its blueprint, to visualize how the surveillance cameras can be oriented to cover the area. A detection system prototype was created for a specific area of the parking lot, using an artificial vision technique to perform the video extraction, while the digital image processing was developed in MATLAB. To complement and achieve the objective, Object-</span><span style="font-family:""> </span><span style="font-family:Verdana;">Oriented Programming (OOP) was used to obtain the count analysis as well as the availability/occupancy of each of the parking areas. This information is shown </span><span style="font-family:Verdana;">o</span><span style="font-family:Verdana;">n a web page, with a simple driver-friendly design, since it has each parking space number and its availability in blue with the word “Available” or, in the opposite case, the word “Taken” in pink.
基金This work was supported by Shota Rustaveli National Science Foundation(SRNSF)[PHDF-19-2224,Improving the efficiency of mechatronic systems in order to ensure the reform of“Industry-4.0”].
文摘The presented work will show the highest relevance of solving all the issues related to this problem and present the results of the analysis of the main expected potential problems,which may occur in the implementation of the INDUSTRY-4.0 reform.It is proved that the pace and level of development of this reform will be determined to a large extent by the effectiveness of the individual nodes used and the entire mechatronic system.It has also been established that as a result of systematic miniaturization of the nodes of radio-electronic equipment and microelectronic equipment and microelectronic technology,the main problem of these reforms and the implementation of complex technological processes is instrumental and technological support,especially with cutting micro-tools and equipment.Therefore,on the example of these investigations,methods for improving their performance are shown.
基金This project is supported by General Electric Company and National Advanced Technology Project of China(No.863-511-942-018).
文摘A novel method to extract conic blending feature in reverse engineering is presented. Different from the methods to recover constant and variable radius blends from unorganized points, it contains not only novel segmentation and feature recognition techniques, but also bias corrected technique to capture more reliable distribution of feature parameters along the spine curve. The segmentation depending on point classification separates the points in the conic blend region from the input point cloud. The available feature parameters of the cross-sectional curves are extracted with the processes of slicing point clouds with planes, conic curve fitting, and parameters estimation and compensation, The extracted parameters and its distribution laws are refined according to statistic theory such as regression analysis and hypothesis test. The proposed method can accurately capture the original design intentions and conveniently guide the reverse modeling process. Application examples are presented to verify the high precision and stability of the proposed method.
文摘A method to reparametrize G retional curve to obtain a C^1 curve is given. A practical G^1 continual connective between adjacent NURUS patches along common guadratic boundary curve is presented in this paper, and a specific algorithm for control points and weights of NURBS patches is discussed.
文摘Constructing Bernstein-Bezier triangular interpolating curve surface interpolating a series of arbitrary disordered data points is of considerable importance for the design and modeling of surfaces with a variety of continuity information. In this article. a kind of simple and reliable algorithm that can process complex field triangular grid generating is presented, and a group of formulae for determining triangular curved surface with wholly C1 continuity are given. It can process arbitrary non-convex boundary and can be used to construct surfaces inner holes.
文摘Using Galois rings and Galois fields, we construct several infinite classes of partial geometric difference sets, and partial geometric difference families, with new parameters. Furthermore, these partial geometric difference sets(and partial geometric difference families) correspond to new infinite families of directed strongly regular graphs. We also discuss some of the links between partially balanced designs, 2-adesigns(which were recently coined by Cunsheng Ding in "Codes from Difference Sets"(2015)), and partial geometric designs, and make an investigation into when a 2-adesign is a partial geometric design.
文摘This paper focuses on analysing the influence of geometric design characteristics on traffic safety using bi-directional data on a divided roadway operated under heterogeneous traffic conditions in India. The study was carried out on a four lane divided inter-city highway in plain and rolling terrain. Statistical modelling approach by Poisson regression and Negative binomial regression were used to assess the safety performance as occurrence of crashes are random events and to identify the influence of the geometric design variables on the crash frequency. Negative binomial regression model was found to be more suitable to identify the variables contributing to road crashes. The study enabled better understanding of the factors related to road geometrics that influence road crash frequency. The study also established that operating speed has a significant contribution to the total number of crashes. Negative binomial models are found to be appropriate to predict road crashes on divided roadways under heterogeneous traffic conditions.
基金This work was financially supported from the National Key Re-search and Development Program of China(No.2021YFB3501700)the National Natural Science Foundation of China(Nos.52202135,61975070,51902143 and 61971207)+7 种基金the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)the Key Research and Development Project of Jiangsu Province(Nos.BE2021040 and BE2019033)the Natural Science Foundation of Jiangsu Province(Nos.BK20191467 and BK20221226)the Postgrad-uate Research&Practice Innovation Program of Jiangsu Province(No.KYCX21_2568)the International S&T Cooperation Program of Jiangsu Province(Nos.BZ2019063,BZ2020045 and BZ2020030)the Natural Science Foundation of the Jiangsu Higher Education In-stitutes of China(Nos.19KJB430018 and 20KJA430003)the Special Project for Technology Innovation of Xuzhou City(Nos.KC19250,KC20201,KC20244 and KC21379)Open Project of State Key Laboratory of Advanced Materials and Electronic Components(No.FHR-JS-202011017).The authors would like to show great appreci-ation to Prof.Ole Bjarlin Jensen from the Technical University of Denmark for his long-term support and guidance on diode laser-related knowledge and technique.
文摘As the fourth-generation light source,solid-state lighting has developed rapidly in the past 30 years due to its advantages of high efficiency and environmental protection.It is widely used in various scenes such as automobile headlights,projection displays,industrial production,and remote lighting.High-power,high-brightness white light-emitting diodes(LEDs)and laser diodes(LDs)technology put forward new requirements for the service stability of color conversion materials.Garnet phosphor ceramics have emerged with their unique advantages of withstanding high power excitation density and the flexibly tunable spectrum.In this article,the research progress of garnet based phosphor ceramics for high-power solid-state lighting was comprehensively reviewed.Firstly,the band gap and coordination environment regulations of luminescence centers of garnet phosphor were summarized.Secondly,the improvement of luminous efficacy via defects regulation was discussed.Thirdly,the relationship between the geometric design and the lighting performance was elucidated.Fourthly,the characterization methods of phosphor ceramics for laser lighting were introduced and illustrated.Finally,the development trend of garnet phosphor ceramics in solid state lighting and display was prospected.
基金supported by the National Natural Science Foundation of China (Nos.60773179,60933008,and 60970079)the National Basic Research Program (973) of China (No.2004CB318000)the China Hungary Joint Project (No.CHN21/2006)
文摘In computer aided geometric design(CAGD),the Bernstein-Bézier system for polynomial space including the triangular domain is an important tool for modeling free form shapes.The Bernstein-like bases for other spaces(trigonometric polynomial,hyperbolic polynomial,or blended space) has also been studied.However,none of them was extended to the triangular domain.In this paper,we extend the linear trigonometric polynomial basis to the triangular domain and obtain a new Bernstein-like basis,which is linearly independent and satisfies positivity,partition of unity,symmetry,and boundary represen-tation.We prove some properties of the corresponding surfaces,including differentiation,subdivision,convex hull,and so forth.Some applications are shown.
基金Supported by the Company ProCAEss GmbH, Landau in der Pfalz, Germany
文摘Non-uniform rational B-spline (NURBS) curves and surfaces are very important tools for model- ling curves and surfaces. Several important details, such as the choice of the sample points, of the parame- terization, and of the termination condition, are however not well described. These details have a great in- fluence on the performance of the approximation algorithm, both in terms of quality as well as time and space usage. This paper described how to sample points, examining two standard parameterizations: equi- distant and chordal. A new and local parameterization, namely an adaptive equidistant model, was pro- posed, which enhances the equidistant model. Localization can also be used to enhance the chordal parameterization. For NURBS surfaces, one must choose which direction will be approximated first and must pay special attention to surfaces of degree 1 which have to be handled as a special case.