The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
J C Galvez - One of the best experts on this subject based on the ideXlab platform.
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on the prediction of the Orientation Factor and fibre distribution of steel and macro synthetic fibres for fibre reinforced concrete
Cement & Concrete Composites, 2017Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C GalvezAbstract:Abstract The Orientation and distribution of the fibres is decisive in the mechanical behaviour of fibre-reinforced concrete. Several classical models have extensively been used for the case of rigid steel fibres. The increasing interest in structural synthetic fibres that can bend demanded new considerations in this matter. A probabilistic model considering the previous research with stereographical assumptions has been performed allowing the use of fibres that can bend. This paper also provides significant tools for design engineering in order to predict and confirm the number of fibres crossing a vertical surface using fibre reinforced concrete with steel and polyolefin fibres. Additionally, the proposed model coincides with the most accepted values and represents with accuracy the existence of boundaries.
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fibre distribution and Orientation of macro synthetic polyolefin fibre reinforced concrete elements
Construction and Building Materials, 2016Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, V AgrawalAbstract:Abstract Fracture behaviour of polyolefin fibre reinforced concrete (PFRC) has proved to be suitable for structural design in construction elements. As in other fibre reinforced materials, the tensile behaviour is strongly affected by the positioning of the fibres. Previous research has assessed this influence by means of fracture tests, showing reliable results. These were obtained by changing the most influencing parameters: the fibre length, the pouring and compaction methods, the concrete type and specimen sizes. However, the influence of these Factors in fracture results is merely limited to the fracture surfaces, while the positioning of the fibres in the rest of the piece may be a key Factor for design in structural elements. Furthermore, examination of the Orientation Factor within the whole piece provides relevant information about the behaviour of the fibres during the pouring processes. It may also allow preparation of future models to predict the final positioning of the fibres. This paper examines the positioning and Orientation of the fibres in elements which provided fracture results previously reported in the literature. In addition to counting the fibres located in the fracture surfaces, the specimens were divided in portions. The fibre-positioning maps obtained provide sound and useful conclusions that may be considered in future design of PFRC elements. The data gathered showed how the Orientation-Factor varied with the flux and vibration, absence of any tendency to float and the noticeable influence of the pouring point in fibre distribution. It also showed that this type of fibre is suitable for structural-size elements, improving the Orientation Factor for longer distances when using self-compacting concrete.
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fracture mechanics of polyolefin fibre reinforced concrete study of the influence of the concrete properties casting procedures the fibre length and specimen size
Engineering Fracture Mechanics, 2016Co-Authors: Marcos G Alberti, A Enfedaque, J C GalvezAbstract:Abstract The final positioning of fibres plays a major role in fibre reinforced concrete (FRC) performance, especially in fracture results used to evaluate the structural competence of the composite material. FRC post-cracking behaviour is related with the number of fibres acting in the cracked surface and the forming angle. This study aims to associate polyolefin fibre Orientation and distribution with several external regular and standardised conditions that have been shown to affect steel-rigid fibres positively. The main sources of anisotropy have been addressed: fresh state properties of the concrete, pouring methods, compaction procedures, wall-effects and formwork geometries. The mechanical properties and fracture behaviour showed a remarkably reliable performance of the polyolefin fibre reinforced concrete. While such variations had an equal fibre dosage of 6 kg/m 3 , the results showed narrow scatter. The fracture surface analysis allowed assessment of the differences, obtaining the Orientation Factor and evaluating wall effects and fibre distribution with each procedure and concrete type.
Marcos Garcia Alberti - One of the best experts on this subject based on the ideXlab platform.
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on the prediction of the Orientation Factor and fibre distribution of steel and macro synthetic fibres for fibre reinforced concrete
Cement & Concrete Composites, 2017Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C GalvezAbstract:Abstract The Orientation and distribution of the fibres is decisive in the mechanical behaviour of fibre-reinforced concrete. Several classical models have extensively been used for the case of rigid steel fibres. The increasing interest in structural synthetic fibres that can bend demanded new considerations in this matter. A probabilistic model considering the previous research with stereographical assumptions has been performed allowing the use of fibres that can bend. This paper also provides significant tools for design engineering in order to predict and confirm the number of fibres crossing a vertical surface using fibre reinforced concrete with steel and polyolefin fibres. Additionally, the proposed model coincides with the most accepted values and represents with accuracy the existence of boundaries.
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fibre distribution and Orientation of macro synthetic polyolefin fibre reinforced concrete elements
Construction and Building Materials, 2016Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, V AgrawalAbstract:Abstract Fracture behaviour of polyolefin fibre reinforced concrete (PFRC) has proved to be suitable for structural design in construction elements. As in other fibre reinforced materials, the tensile behaviour is strongly affected by the positioning of the fibres. Previous research has assessed this influence by means of fracture tests, showing reliable results. These were obtained by changing the most influencing parameters: the fibre length, the pouring and compaction methods, the concrete type and specimen sizes. However, the influence of these Factors in fracture results is merely limited to the fracture surfaces, while the positioning of the fibres in the rest of the piece may be a key Factor for design in structural elements. Furthermore, examination of the Orientation Factor within the whole piece provides relevant information about the behaviour of the fibres during the pouring processes. It may also allow preparation of future models to predict the final positioning of the fibres. This paper examines the positioning and Orientation of the fibres in elements which provided fracture results previously reported in the literature. In addition to counting the fibres located in the fracture surfaces, the specimens were divided in portions. The fibre-positioning maps obtained provide sound and useful conclusions that may be considered in future design of PFRC elements. The data gathered showed how the Orientation-Factor varied with the flux and vibration, absence of any tendency to float and the noticeable influence of the pouring point in fibre distribution. It also showed that this type of fibre is suitable for structural-size elements, improving the Orientation Factor for longer distances when using self-compacting concrete.
A Enfedaque - One of the best experts on this subject based on the ideXlab platform.
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on the prediction of the Orientation Factor and fibre distribution of steel and macro synthetic fibres for fibre reinforced concrete
Cement & Concrete Composites, 2017Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C GalvezAbstract:Abstract The Orientation and distribution of the fibres is decisive in the mechanical behaviour of fibre-reinforced concrete. Several classical models have extensively been used for the case of rigid steel fibres. The increasing interest in structural synthetic fibres that can bend demanded new considerations in this matter. A probabilistic model considering the previous research with stereographical assumptions has been performed allowing the use of fibres that can bend. This paper also provides significant tools for design engineering in order to predict and confirm the number of fibres crossing a vertical surface using fibre reinforced concrete with steel and polyolefin fibres. Additionally, the proposed model coincides with the most accepted values and represents with accuracy the existence of boundaries.
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fibre distribution and Orientation of macro synthetic polyolefin fibre reinforced concrete elements
Construction and Building Materials, 2016Co-Authors: Marcos Garcia Alberti, A Enfedaque, J C Galvez, V AgrawalAbstract:Abstract Fracture behaviour of polyolefin fibre reinforced concrete (PFRC) has proved to be suitable for structural design in construction elements. As in other fibre reinforced materials, the tensile behaviour is strongly affected by the positioning of the fibres. Previous research has assessed this influence by means of fracture tests, showing reliable results. These were obtained by changing the most influencing parameters: the fibre length, the pouring and compaction methods, the concrete type and specimen sizes. However, the influence of these Factors in fracture results is merely limited to the fracture surfaces, while the positioning of the fibres in the rest of the piece may be a key Factor for design in structural elements. Furthermore, examination of the Orientation Factor within the whole piece provides relevant information about the behaviour of the fibres during the pouring processes. It may also allow preparation of future models to predict the final positioning of the fibres. This paper examines the positioning and Orientation of the fibres in elements which provided fracture results previously reported in the literature. In addition to counting the fibres located in the fracture surfaces, the specimens were divided in portions. The fibre-positioning maps obtained provide sound and useful conclusions that may be considered in future design of PFRC elements. The data gathered showed how the Orientation-Factor varied with the flux and vibration, absence of any tendency to float and the noticeable influence of the pouring point in fibre distribution. It also showed that this type of fibre is suitable for structural-size elements, improving the Orientation Factor for longer distances when using self-compacting concrete.
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fracture mechanics of polyolefin fibre reinforced concrete study of the influence of the concrete properties casting procedures the fibre length and specimen size
Engineering Fracture Mechanics, 2016Co-Authors: Marcos G Alberti, A Enfedaque, J C GalvezAbstract:Abstract The final positioning of fibres plays a major role in fibre reinforced concrete (FRC) performance, especially in fracture results used to evaluate the structural competence of the composite material. FRC post-cracking behaviour is related with the number of fibres acting in the cracked surface and the forming angle. This study aims to associate polyolefin fibre Orientation and distribution with several external regular and standardised conditions that have been shown to affect steel-rigid fibres positively. The main sources of anisotropy have been addressed: fresh state properties of the concrete, pouring methods, compaction procedures, wall-effects and formwork geometries. The mechanical properties and fracture behaviour showed a remarkably reliable performance of the polyolefin fibre reinforced concrete. While such variations had an equal fibre dosage of 6 kg/m 3 , the results showed narrow scatter. The fracture surface analysis allowed assessment of the differences, obtaining the Orientation Factor and evaluating wall effects and fibre distribution with each procedure and concrete type.
Zhao Shi - One of the best experts on this subject based on the ideXlab platform.
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an optimized ant colony algorithm based on the gradual changing Orientation Factor for multi constraint qos routing
Computer Communications, 2009Co-Authors: Hua Wang, Zhao ShiAbstract:The ad hoc network has been attracting increasing attention of researchers owing to its good performance and special application. The search of route that satisfies such multi-constraints as delay, jitter and bandwidth in ad hoc network can facilitate the solution to multi-media transmission. The problem of multi-constraint is generally an NP-Hard problem. This paper deals with the problem by adding an Orientation heuristic Factor to the conventional ant colony algorithm, which enables the ant to get rid of the blindness at the initial stage of path searching. The ant in the modified algorithm not only makes use of the previous search findings, but also reduces the misguiding effect of pheromones on the irrelevant paths, thus overcoming the problem of slow convergence. The choice and the extent of the effect of the Orientation heuristic Factor in the modified algorithm is our focus, and the gradual changing Orientation Factors is also studied. The gradual changing Orientation Factor not only enables the ant to take advantage of direction to assist path search, but also adjust convergence speed and exactitude. Simulation results indicate that the modified algorithm can quickly find the feasible solution to the network routing problem. The method adopted can help find better solutions in shorter time.
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Multicast routing for delay variation bound using a modified ant colony algorithm
Journal of Network and Computer Applications, 2009Co-Authors: Hua Wang, Zhao ShiAbstract:The delay and delay variation-bounded Steiner tree problem is an important multicast routing problem in real-time multimedia networks. Such a constrained Steiner tree problem is known to be NP-complete. This paper proposes an ant colony algorithm with Orientation Factor and applies it to multicast routing problem with the constraints of delay variation bound. The Orientation Factor enables the ant to get rid of the initial blindness when searching paths, makes use of the search results and reduces the misguiding effect of pheromone on irrelevant paths, thus overcoming the drawbacks of slow convergence existing in the basic ant colony algorithm, increasing the speed of convergence and speeding up the finding of feasible solution to the problem. The simulation results show that the modified algorithm makes it possible to find a feasible solution to the multicast routing problem with delay variation bound. Compared with the conventional ant colony algorithm, the convergence speed of the modified algorithm is improved.
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an ant colony algorithm based on Orientation Factor for qos multicast routing in ad hoc networks
International Conference on Communications, 2008Co-Authors: Hua Wang, Zhao ShiAbstract:The ad hoc network has been attracting more and more attention for its special attributes and applications. This paper proposes an ant colony algorithm with Orientation Factor and applies it to multicast routing problem with multi-constraints QoS in the ad hoc network. The Orientation Factor is a heuristic element based on GPS, which enables the ant to get rid of the initial blindness when searching paths, and overcome the drawbacks of slow convergence existing in the basic ant colony algorithm, increasing the speed of convergence and speeding up the finding of feasible solution to the multi-constraint problem. Simulation results show that the modified algorithm makes it possible to find feasible solution to the multicast routing problem with delay and delay variation-bounded. And compared with the conventional ant colony algorithm, the convergence speed of the modified algorithm is improved and the number of packets used for computing routing decreases obviously.
Oscar Antonio Ruano - One of the best experts on this subject based on the ideXlab platform.
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influence of texture and grain size on work hardening and ductility in magnesium based alloys processed by ecap and rolling
Acta Materialia, 2006Co-Authors: J A Del Valle, Fernando Carreno, Oscar Antonio RuanoAbstract:Equal channel angular pressing (ECAP) and large-strain hot rolling (LSHR) are widely used methods for refining the grain size in magnesium alloys. The hardening capability of the processed materials confers the resistance to develop tensile mechanical instabilities, therefore controlling ductility. In this work various magnesium alloys were processed using ECAP, LSHR and annealing treatments in order to control the texture and the grain size. Emphasis was laid upon the influence of these Factors on work hardening behavior and dynamic recovery. In addition to the direct effect of texture through the change in the Orientation Factor for basal and prismatic slip, effects were found on dynamic recovery and the appearance of stage II of work hardening. The grain size refinement causes a strong decrease in the hardening rate. A contribution of grain boundary sliding to deformation gives a plausible explanation of these results.
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influence of texture and grain size on work hardening and ductility in magnesium based alloys processed by ecap and rolling
Acta Materialia, 2006Co-Authors: J A Del Valle, Fernando Carreno, Oscar Antonio RuanoAbstract:Equal channel angular pressing (ECAP) and large-strain hot rolling (LSHR) are widely used methods for refining the grain size in magnesium alloys. The hardening capability of the processed materials confers the resistance to develop tensile mechanical instabilities, therefore controlling ductility. In this work various magnesium alloys were processed using ECAP, LSHR and annealing treatments in order to control the texture and the grain size. Emphasis was laid upon the influence of these Factors on work hardening behavior and dynamic recovery. In addition to the direct effect of texture through the change in the Orientation Factor for basal and prismatic slip, effects were found on dynamic recovery and the appearance of stage II of work hardening. The grain size refinement causes a strong decrease in the hardening rate. A contribution of grain boundary sliding to deformation gives a plausible explanation of these results.