Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer ...Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer range）, but it does not always hold in nanoindentation experiments （indentation depths approaching the nanometer range）. Indenter tip radius effect has been proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao＇s relationship. We have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary dislocations. The comparison between numerical result and Feng and Nix＇s experimental data shows that the indenter tip radius effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.展开更多
In the present work,an attempt is made to partially replace high cost silica sand with sustainable eco-friendly cow-dung.The practical utility of cow dung as an additive material that facilitates binding in sand mould...In the present work,an attempt is made to partially replace high cost silica sand with sustainable eco-friendly cow-dung.The practical utility of cow dung as an additive material that facilitates binding in sand moulds has been tested.The Taguchi method is used to plan and conduct nine experiments with three replicates each.Pareto analysis of variance study is performed to understand the practical significance of moulding sand variables,that is,percentage of cow dung,clay,water,and degree of ramming on sand mould properties.The conflicting multiple objective functions(maximize mould hardness,and minimize collapsibility and gas evolution)are optimized by utilizing the Data Envelopment Analysis Ranking(DEAR)method.The optimal parameters i.e.6%of clay,4%of water,5%of cow-dung and 4 numbers of ramming strokes are obtained by applying a hybrid Taguchi-DEAR method.These parameters show the best moulding properties are:mould hardness 55,gas evolution 5.9 ml·g-1,and collapsibility 470 g·cm-2.Thereafter,a Lovejoy coupling made of aluminium is cast in the sand mould prepared with cow dung and without cow dung,with the optimum set of parameters.The mechanical properties,surface finish,and microstructure of the casting cast with cow-dung are better than that without cowdung.展开更多
A novel robust fault diagnosis scheme, which possesses fault estimate capability as well as fault diagnosis property, is proposed. The scheme is developed based on a suitable combination of the adaptive multiple model...A novel robust fault diagnosis scheme, which possesses fault estimate capability as well as fault diagnosis property, is proposed. The scheme is developed based on a suitable combination of the adaptive multiple model （AMM） and unknown input observer （UIO）. The main idea of the proposed scheme stems from the fact that the actuator Lock-in-Place fault is unknown （when and where the actuator gets locked are unknown）, and multiple models are used to describe different fault scenarios, then a bank of unknown input observers are designed to implement the disturbance de-coupling. According to Lyapunov theory, proof of the robustness of the newly developed scheme in the presence of faults and disturbances is derived. Numerical simulation results on an aircraft example show satisfactory performance of the proposed algorithm.展开更多
Looking upon every encoding state of quantum information systems as a quantum information pattern, A kind of pattern-distance between different patterns as a measurement of comparability of quantum information pattern...Looking upon every encoding state of quantum information systems as a quantum information pattern, A kind of pattern-distance between different patterns as a measurement of comparability of quantum information patterns is defined, and two kinds of recognition algorithms based on pattern-distance for quantum information are proposed. They can respectively recognize quantum information with known objective pattern and unknown objective pattern. In the two algorithms, the phases and occurrence probabilities of different eigenpattems of quantum information are sufficiently considered. Two examples demonstrate the feasibility and effectiveness of the two recognition methods. These algorithms point out a new and important path for applications of quantum information and pattern recognition.展开更多
基金The project supported by the National Natural Science Foundation of China (10121202)the Ministry of Education of China (20020003023)
文摘Nix and Gao established an important relation between the microindentation hardness and indentation depth. Such a relation has been verified by many microindentation experiments （indentation depths in the micrometer range）, but it does not always hold in nanoindentation experiments （indentation depths approaching the nanometer range）. Indenter tip radius effect has been proposed by Qu et al. and others as possibly the main factor that causes the deviation from Nix and Gao＇s relationship. We have developed an indentation model for micro- and nanoindentation, which accounts for two indenter shapes, a sharp, conical indenter and a conical indenter with a spherical tip. The analysis is based on the conventional theory of mechanism-based strain gradient plasticity established from the Taylor dislocation model to account for the effect of geometrically necessary dislocations. The comparison between numerical result and Feng and Nix＇s experimental data shows that the indenter tip radius effect indeed causes the deviation from Nix-Gao relation, but it seems not be the main factor.
文摘In the present work,an attempt is made to partially replace high cost silica sand with sustainable eco-friendly cow-dung.The practical utility of cow dung as an additive material that facilitates binding in sand moulds has been tested.The Taguchi method is used to plan and conduct nine experiments with three replicates each.Pareto analysis of variance study is performed to understand the practical significance of moulding sand variables,that is,percentage of cow dung,clay,water,and degree of ramming on sand mould properties.The conflicting multiple objective functions(maximize mould hardness,and minimize collapsibility and gas evolution)are optimized by utilizing the Data Envelopment Analysis Ranking(DEAR)method.The optimal parameters i.e.6%of clay,4%of water,5%of cow-dung and 4 numbers of ramming strokes are obtained by applying a hybrid Taguchi-DEAR method.These parameters show the best moulding properties are:mould hardness 55,gas evolution 5.9 ml·g-1,and collapsibility 470 g·cm-2.Thereafter,a Lovejoy coupling made of aluminium is cast in the sand mould prepared with cow dung and without cow dung,with the optimum set of parameters.The mechanical properties,surface finish,and microstructure of the casting cast with cow-dung are better than that without cowdung.
基金the National Natural Science Foundation of China (60574083)Aeronautics Science Foun-dation of China (2007ZC52039)
文摘A novel robust fault diagnosis scheme, which possesses fault estimate capability as well as fault diagnosis property, is proposed. The scheme is developed based on a suitable combination of the adaptive multiple model （AMM） and unknown input observer （UIO）. The main idea of the proposed scheme stems from the fact that the actuator Lock-in-Place fault is unknown （when and where the actuator gets locked are unknown）, and multiple models are used to describe different fault scenarios, then a bank of unknown input observers are designed to implement the disturbance de-coupling. According to Lyapunov theory, proof of the robustness of the newly developed scheme in the presence of faults and disturbances is derived. Numerical simulation results on an aircraft example show satisfactory performance of the proposed algorithm.
文摘Looking upon every encoding state of quantum information systems as a quantum information pattern, A kind of pattern-distance between different patterns as a measurement of comparability of quantum information patterns is defined, and two kinds of recognition algorithms based on pattern-distance for quantum information are proposed. They can respectively recognize quantum information with known objective pattern and unknown objective pattern. In the two algorithms, the phases and occurrence probabilities of different eigenpattems of quantum information are sufficiently considered. Two examples demonstrate the feasibility and effectiveness of the two recognition methods. These algorithms point out a new and important path for applications of quantum information and pattern recognition.
