A new type of Bragg fibers, i.e. hollow-core cobweb-structured optical fibers, which can be used to the low-loss transmis- sion from visible to near infrared region (0.65 μm-1.55 μm), terahertz wave (200 μm-480 μm...A new type of Bragg fibers, i.e. hollow-core cobweb-structured optical fibers, which can be used to the low-loss transmis- sion from visible to near infrared region (0.65 μm-1.55 μm), terahertz wave (200 μm-480 μm) and circular-polariza- tion-maintaining single-mode transmission are investigated. Results show that the hollow-core cobweb-structured fibers have less loss than other hollow-core Bragg fibers. The fibers can be constituted by using the plastics or glasses with large absorption losses.展开更多
The relationship between forms and forces is one of the main topics of structural morphology. This harmonious coexisting link is very strong for systems in tensegrity state, commonly called ＂tensegrity systems＂. It ...The relationship between forms and forces is one of the main topics of structural morphology. This harmonious coexisting link is very strong for systems in tensegrity state, commonly called ＂tensegrity systems＂. It is currently apparent that, among the tensegrity systems, there also exist cable-bar cells with a discontinuous network of cables. It is possible to design a separate set of cables inside the cable-bar elementary cell and to establish a self-stress state of equilibrium. In this connection, the author of this paper suggested to assume a new Class-Theta tensegrity systems. Each of the basic tensegrity systems termed Class-Theta possesses an external and internal set of tension components. The shape of Greek capital letter 69 （Theta） reflects two sets of such components （two sets of tendons, cables, etc.）. This notation corresponds to Skelton＇s Class-k tensegrity structure. As shown in this paper, the Class-Theta tensegrity cell can exemplify a geometrically and practically useful form for the lightweight and long-span modular structures, mainly but not only in view of civil engineering and architecture.展开更多
Conventionally, direct tensile tests are employed to measure mechanical properties of industrially pro- duced products. In mass production, the cost of sampling and labor is high, which leads to an increase of total p...Conventionally, direct tensile tests are employed to measure mechanical properties of industrially pro- duced products. In mass production, the cost of sampling and labor is high, which leads to an increase of total pro- duction cost and a decrease of production efficiency. The main purpose of this paper is to develop an intelligent pro- gram based on artificial neural network （ANN） to predict the mechanical properties of a commercial grade hot rolled low carbon steel strip, SPHC. A neural network model was developed by using 7 x 5 x 1 back-propagation （BP） neural network structure to determine the multiple relationships among chemical composition, product pro- cess and mechanical properties. Industrial on-line application of the model indicated that prediction results were in good agreement with measured values. It showed that 99.2 % of the products＇ tensile strength was accurately pre- dicted within an error margin of ~ 10 %, compared to measured values. Based on the model, the effects of chemical composition and hot rolling process on mechanical properties were derived and the relative importance of each in- put parameter was evaluated by sensitivity analysis. All the results demonstrate that the developed ANN models are capable of accurate predictions under real-time industrial conditions. The developed model can be used to sub- stitute mechanical property measurement and therefore reduce cost of production. It can also be used to control and optimize mechanical properties of the investigated steel.展开更多
The structural evolution of dislocation network is closely related to y' rafting and tensile properties. In this work, the effects of strain rate and temperature on the structural evolution of interface dislocatio...The structural evolution of dislocation network is closely related to y' rafting and tensile properties. In this work, the effects of strain rate and temperature on the structural evolution of interface dislocation network in Ni-based superalloys are studied by molecular dynamics simulations. The correlation between the evolution of dislocation network and tensile properties is also explored. The results indicate that the dislocation network shows different degrees of deformation and damage at various strain rates and temperatures. The ),' rafting depends on the damage structure of dislocation network at various strain rates and tem- peratures. Moreover, the tensile properties of interface in Ni-based superalloys are closely related to the evolution of disloca- tion network and dislocation motion mechanisms.展开更多
基金the National Natural Science Foundationof China (No. 60577009, 60444003)
文摘A new type of Bragg fibers, i.e. hollow-core cobweb-structured optical fibers, which can be used to the low-loss transmis- sion from visible to near infrared region (0.65 μm-1.55 μm), terahertz wave (200 μm-480 μm) and circular-polariza- tion-maintaining single-mode transmission are investigated. Results show that the hollow-core cobweb-structured fibers have less loss than other hollow-core Bragg fibers. The fibers can be constituted by using the plastics or glasses with large absorption losses.
文摘The relationship between forms and forces is one of the main topics of structural morphology. This harmonious coexisting link is very strong for systems in tensegrity state, commonly called ＂tensegrity systems＂. It is currently apparent that, among the tensegrity systems, there also exist cable-bar cells with a discontinuous network of cables. It is possible to design a separate set of cables inside the cable-bar elementary cell and to establish a self-stress state of equilibrium. In this connection, the author of this paper suggested to assume a new Class-Theta tensegrity systems. Each of the basic tensegrity systems termed Class-Theta possesses an external and internal set of tension components. The shape of Greek capital letter 69 （Theta） reflects two sets of such components （two sets of tendons, cables, etc.）. This notation corresponds to Skelton＇s Class-k tensegrity structure. As shown in this paper, the Class-Theta tensegrity cell can exemplify a geometrically and practically useful form for the lightweight and long-span modular structures, mainly but not only in view of civil engineering and architecture.
文摘Conventionally, direct tensile tests are employed to measure mechanical properties of industrially pro- duced products. In mass production, the cost of sampling and labor is high, which leads to an increase of total pro- duction cost and a decrease of production efficiency. The main purpose of this paper is to develop an intelligent pro- gram based on artificial neural network （ANN） to predict the mechanical properties of a commercial grade hot rolled low carbon steel strip, SPHC. A neural network model was developed by using 7 x 5 x 1 back-propagation （BP） neural network structure to determine the multiple relationships among chemical composition, product pro- cess and mechanical properties. Industrial on-line application of the model indicated that prediction results were in good agreement with measured values. It showed that 99.2 % of the products＇ tensile strength was accurately pre- dicted within an error margin of ~ 10 %, compared to measured values. Based on the model, the effects of chemical composition and hot rolling process on mechanical properties were derived and the relative importance of each in- put parameter was evaluated by sensitivity analysis. All the results demonstrate that the developed ANN models are capable of accurate predictions under real-time industrial conditions. The developed model can be used to sub- stitute mechanical property measurement and therefore reduce cost of production. It can also be used to control and optimize mechanical properties of the investigated steel.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11072026 and 11102139)the Fundamental Research Funds for the Central Universities (Grant No. 2009JBZ015)China Postdoctoral Science Foundation (Grant No. 20110491205)
文摘The structural evolution of dislocation network is closely related to y' rafting and tensile properties. In this work, the effects of strain rate and temperature on the structural evolution of interface dislocation network in Ni-based superalloys are studied by molecular dynamics simulations. The correlation between the evolution of dislocation network and tensile properties is also explored. The results indicate that the dislocation network shows different degrees of deformation and damage at various strain rates and temperatures. The ),' rafting depends on the damage structure of dislocation network at various strain rates and tem- peratures. Moreover, the tensile properties of interface in Ni-based superalloys are closely related to the evolution of disloca- tion network and dislocation motion mechanisms.
