Due to the immaturity of practice and the increasing complexity of system of system (SoS). It is necessary to develop systematic methodologies that enable evolution of such systems. This paper presents a prototype d...Due to the immaturity of practice and the increasing complexity of system of system (SoS). It is necessary to develop systematic methodologies that enable evolution of such systems. This paper presents a prototype design for a synthetic system evolution environment (SEE). It outlines the purpose of the environment, describes its concept of operations, details its main functions and processes in utilizing the system architecture knowledge for systems evolution, and introduces its initial high level architecture design.In addition, it also documents the approach for developing the environment.展开更多
A growing number of three-dimensional(3D)-print- ing processes have been applied to tissue engineering. This paper presents a state-of-the-art study of 3D-printing technologies for tissue-engineering applications, wit...A growing number of three-dimensional(3D)-print- ing processes have been applied to tissue engineering. This paper presents a state-of-the-art study of 3D-printing technologies for tissue-engineering applications, with particular focus on the development of a computer-aided scaffold design system; the direct 3D printing of functionally graded scaffolds; the modeling of selective laser sintering(SLS) and fused deposition modeling(FDM) processes; the indirect additive manufacturing of scaffolds, with both micro and macro features; the development of a bioreactor; and 3D/4D bioprinting. Technological limitations will be discussed so as to highlight the possibility of future improvements for new 3D-printing methodologies for tissue engineering.展开更多
The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkabl...The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkable reduction of bending stresses in the arches and tie beams. The present paper describes the main features of the design and construction of several long-span arch bridges of this typology in Spain： the three pedestrian footbridges for the Madrid cycling ring track, with spans of 52, 60 and 80 m, the Bridge over River Deba in Guipuzcoa with a span of 110 m and Palma del Rio Bridge over River Guadalquivir in Cordoba, 130 m long. In all cases, two inclined arches linked at the crown were implemented, a very effective disposition to reduce the out-of-plane buckling length. The multiple crossings of the hanger system, consisting of prestressed bars in the case of Deba Bridge and the footbridges, and locked coil cables for Palma del Rio Bridge, were dealt with by means of crossing devices which led to a technically satisfactory solution with minimal visual impact. An innovative approach to bowstring arches was introduced in Valdebebas Bridge over M-12 motorway in Madrid, next to the new T-4 Terminal of Barajas Airport, with a span of 162 m, where the hangers are replaced by a structural steel mesh -diagrid- which acts as the web of a simply-supported beam whose compression head is the arch and the tie beam is the deck.展开更多
When designing vehicle suspension systems, compromises are usually made when setting the range of values for spring stiffness and damping constant. Suspension parameters are set depending on the operational requiremen...When designing vehicle suspension systems, compromises are usually made when setting the range of values for spring stiffness and damping constant. Suspension parameters are set depending on the operational requirements of the market. Passenger car for example, would require high quality damping while off road vehicle requires high spring stiffness setting. A quarter vehicle suspension model has been used to study the suspension transmissibility in handling and ride at various frequency ratios. The results obtained show that as the frequency ratio increases, transmissibility for handling reduces with increasing suspension stiffness and increases as the damping constant is increased. On the other hand, transmissibility for ride deteriorate as the spring constant is increased but approaches the ideal as the damping constant is increased. The dynamic magnification of the sprung masses reduces while that of the unsprung masses improves as the frequency ratio is increased.展开更多
There are many structural lateral systems used in tall buildings： rigid frames, braced frames, shear walls, tubular structures and core structures. The outrigger and belt truss systems are efficient structures for dr...There are many structural lateral systems used in tall buildings： rigid frames, braced frames, shear walls, tubular structures and core structures. The outrigger and belt truss systems are efficient structures for drift control and base moment reduction in tall buildings where the core alone is not rigid enough to resist lateral loads. Perimeter columns are mobilized for increasing the effective width of the structure, and they developed tension in the windward columns and compression in the leeward columns. Optimum locations for the outriggers have been studied because of the influence on the top displacement and base moment in the core. It was analyzed the optimal position for two to seven outriggers and belt trusses, aiming to achieve minimum bending moment and minimum drift.展开更多
There is a variety of PDSs （project delivery systems） in today＇s construction industry. This leads to confusion when it comes to selecting the most suitable PDS for a specific project. The wrong selection decision ...There is a variety of PDSs （project delivery systems） in today＇s construction industry. This leads to confusion when it comes to selecting the most suitable PDS for a specific project. The wrong selection decision might lead eventually to reduced profit margins or perhaps financial losses to PSFs （professional service firms）. This research proposes a conceptual framework that helps PSFs in the selection of one or more suitable PDSs for their construction operations. The framework uses SWOT （strengths, weaknesses, opportunities and threats） analysis as a tool for assessing each PDS considered in this research. The PDSs included in the framework are design-bid-build, design-build, construction management agency, public-private partnerships and integrated project delivery. The main aim of this research framework is to enhance decision-making efficiency in PDS selection for PSF operations.展开更多
The fact that the security facilities within a system are closely coupled and the security facilities between systems are unconnected results in an isolated protection structure for systems, and gives rise to a seriou...The fact that the security facilities within a system are closely coupled and the security facilities between systems are unconnected results in an isolated protection structure for systems, and gives rise to a serious challenge to system security integrations and system controls. Also, the need for diversified services and flexible extensions of network security asks for more considerations and contribu?tions from the perspective of software engineering in the process of designing and constructing security systems. Based on the essence of the virtualization technique and the idea of software-defined networks, we in this paper propose a novel software-defi ned security architecture for systems. By abstracting the traditional security facilities and techniques, the proposed security architecture provides a new, simple, effective, and programmable framework in which security operations and security controls can be decoupled, and thereby reduces the software module sizes, decreases the intensity of software deve?lopments, and improves the security extensibility of systems.展开更多
In the complex multicore chip system,network on-chip(NoC)is viewed as a kind of system interconnection that can substitute the traditional interconnect networks,which will improve the system performance and communicat...In the complex multicore chip system,network on-chip(NoC)is viewed as a kind of system interconnection that can substitute the traditional interconnect networks,which will improve the system performance and communication efficiency.With regard to the complex and large scale NoC,simple and efficient routing nodes are the critical factors to achieve low-cost and low-congestion communication performance.This paper proposes an unbuffered switch architecture and makes detailed analysis of the mechanism of buffer in the switch architecture.According to the simulation results,the S-mesh using the unbuffered switch architecture is better in terms of the optimal performance in message latency than some typical NoC architectures,such as 2D-mesh,Fat-tree,Butterfly,Octagon and so on.The synthesis results of design compiler indicate that the unbuffered switch has obvious advantages of achieving cost and operating speed for the chips.展开更多
文摘Due to the immaturity of practice and the increasing complexity of system of system (SoS). It is necessary to develop systematic methodologies that enable evolution of such systems. This paper presents a prototype design for a synthetic system evolution environment (SEE). It outlines the purpose of the environment, describes its concept of operations, details its main functions and processes in utilizing the system architecture knowledge for systems evolution, and introduces its initial high level architecture design.In addition, it also documents the approach for developing the environment.
基金Singapore National Research Foundation (NRF) for funding the Singapore Centre for 3D Printing (SC3DP)
文摘A growing number of three-dimensional(3D)-print- ing processes have been applied to tissue engineering. This paper presents a state-of-the-art study of 3D-printing technologies for tissue-engineering applications, with particular focus on the development of a computer-aided scaffold design system; the direct 3D printing of functionally graded scaffolds; the modeling of selective laser sintering(SLS) and fused deposition modeling(FDM) processes; the indirect additive manufacturing of scaffolds, with both micro and macro features; the development of a bioreactor; and 3D/4D bioprinting. Technological limitations will be discussed so as to highlight the possibility of future improvements for new 3D-printing methodologies for tissue engineering.
文摘The use of Network hanger arrangement, a development of the classical Nielsen V-hanger system, in steel bowstring arch bridges allows for important steel saving, with very slender main elements, owing to the remarkable reduction of bending stresses in the arches and tie beams. The present paper describes the main features of the design and construction of several long-span arch bridges of this typology in Spain： the three pedestrian footbridges for the Madrid cycling ring track, with spans of 52, 60 and 80 m, the Bridge over River Deba in Guipuzcoa with a span of 110 m and Palma del Rio Bridge over River Guadalquivir in Cordoba, 130 m long. In all cases, two inclined arches linked at the crown were implemented, a very effective disposition to reduce the out-of-plane buckling length. The multiple crossings of the hanger system, consisting of prestressed bars in the case of Deba Bridge and the footbridges, and locked coil cables for Palma del Rio Bridge, were dealt with by means of crossing devices which led to a technically satisfactory solution with minimal visual impact. An innovative approach to bowstring arches was introduced in Valdebebas Bridge over M-12 motorway in Madrid, next to the new T-4 Terminal of Barajas Airport, with a span of 162 m, where the hangers are replaced by a structural steel mesh -diagrid- which acts as the web of a simply-supported beam whose compression head is the arch and the tie beam is the deck.
文摘When designing vehicle suspension systems, compromises are usually made when setting the range of values for spring stiffness and damping constant. Suspension parameters are set depending on the operational requirements of the market. Passenger car for example, would require high quality damping while off road vehicle requires high spring stiffness setting. A quarter vehicle suspension model has been used to study the suspension transmissibility in handling and ride at various frequency ratios. The results obtained show that as the frequency ratio increases, transmissibility for handling reduces with increasing suspension stiffness and increases as the damping constant is increased. On the other hand, transmissibility for ride deteriorate as the spring constant is increased but approaches the ideal as the damping constant is increased. The dynamic magnification of the sprung masses reduces while that of the unsprung masses improves as the frequency ratio is increased.
文摘There are many structural lateral systems used in tall buildings： rigid frames, braced frames, shear walls, tubular structures and core structures. The outrigger and belt truss systems are efficient structures for drift control and base moment reduction in tall buildings where the core alone is not rigid enough to resist lateral loads. Perimeter columns are mobilized for increasing the effective width of the structure, and they developed tension in the windward columns and compression in the leeward columns. Optimum locations for the outriggers have been studied because of the influence on the top displacement and base moment in the core. It was analyzed the optimal position for two to seven outriggers and belt trusses, aiming to achieve minimum bending moment and minimum drift.
文摘There is a variety of PDSs （project delivery systems） in today＇s construction industry. This leads to confusion when it comes to selecting the most suitable PDS for a specific project. The wrong selection decision might lead eventually to reduced profit margins or perhaps financial losses to PSFs （professional service firms）. This research proposes a conceptual framework that helps PSFs in the selection of one or more suitable PDSs for their construction operations. The framework uses SWOT （strengths, weaknesses, opportunities and threats） analysis as a tool for assessing each PDS considered in this research. The PDSs included in the framework are design-bid-build, design-build, construction management agency, public-private partnerships and integrated project delivery. The main aim of this research framework is to enhance decision-making efficiency in PDS selection for PSF operations.
基金supported in part by the following grants:National Science Foundation of China(Grant No.61272400)Chongqing Innovative Team Fund for College Development Project(Grant No.KJTD201310)+3 种基金Chongqing Youth Innovative Talent Project(Grant No.cstc2013kjrc-qnrc40004)Science and Technology Research Program of the Chongqing Municipal Education Committee(Grant No.KJ1500425)Foundation of CQUPT(Grant No.WF201403)Chongqing Graduate Research and Innovation Project(Grant No.CYS14146)
文摘The fact that the security facilities within a system are closely coupled and the security facilities between systems are unconnected results in an isolated protection structure for systems, and gives rise to a serious challenge to system security integrations and system controls. Also, the need for diversified services and flexible extensions of network security asks for more considerations and contribu?tions from the perspective of software engineering in the process of designing and constructing security systems. Based on the essence of the virtualization technique and the idea of software-defined networks, we in this paper propose a novel software-defi ned security architecture for systems. By abstracting the traditional security facilities and techniques, the proposed security architecture provides a new, simple, effective, and programmable framework in which security operations and security controls can be decoupled, and thereby reduces the software module sizes, decreases the intensity of software deve?lopments, and improves the security extensibility of systems.
基金Supported by the National High Technology Research and Development Program of China(No.2009AA01Z105)the Ministry of EducationIntel Special Foundation for Information Technology(No.MOE-INTEL-08-05)the Postdoctoral Science Foundation of China(No.20080440942,200902432)
文摘In the complex multicore chip system,network on-chip(NoC)is viewed as a kind of system interconnection that can substitute the traditional interconnect networks,which will improve the system performance and communication efficiency.With regard to the complex and large scale NoC,simple and efficient routing nodes are the critical factors to achieve low-cost and low-congestion communication performance.This paper proposes an unbuffered switch architecture and makes detailed analysis of the mechanism of buffer in the switch architecture.According to the simulation results,the S-mesh using the unbuffered switch architecture is better in terms of the optimal performance in message latency than some typical NoC architectures,such as 2D-mesh,Fat-tree,Butterfly,Octagon and so on.The synthesis results of design compiler indicate that the unbuffered switch has obvious advantages of achieving cost and operating speed for the chips.
