Isothermal flashless die forging process of Ti - alloy structural air - frame part with varying thickness rib has been modelled in this paper.The results of present study show that a upside - down trapezoid rib would...Isothermal flashless die forging process of Ti - alloy structural air - frame part with varying thickness rib has been modelled in this paper.The results of present study show that a upside - down trapezoid rib would be formed and buckling would occure as blank is reduced,if the thickness of billet is maller than or equal to the thickness of rib. During modelling process of structural air frame part with E type cross - section rib, the saddle or lap would be formed finally at the middle of transverse rib between ribs with increase in deformation.If metal is allowed to flow out at confluence of longitudinal and transverse rib, the lop defect would be eliminated,, but a pipe cavity is obvious on corresponding loca- tion of blank. of defect formation depends on distance of metal flow ,friction,temperature homoge- neity of the blank and complexity of the part.展开更多
In this paper, an EPQ-based inventory policy for an item is presented with stock-dependent demand during two trade credit periods. In addition, there is a provision for 1) an immediate part payment to the wholesaler, ...In this paper, an EPQ-based inventory policy for an item is presented with stock-dependent demand during two trade credit periods. In addition, there is a provision for 1) an immediate part payment to the wholesaler, 2) borrowing some money from money lending source for the immediate part payment, 3) here supplier or wholesaler offers a trade credit period to his retailer and retailer also offers a trade credit period to his customer. Against the above conjectures inventory model has been formulated with respect to the retailer’s point of view for minimizing the total inventory cost. The non-linear optimization method-Generalized Reduced Gradient (GRG) method is used to find the optimal solutions. Lastly Numerical examples are set to illustrate this model. Finally we use LINGO software to solve this model.展开更多
As a typical machine-learning based detection technique, deformable part models(DPM)achieve great success in detecting complex object categories. The heavy computational burden of DPM,however, severely restricts their...As a typical machine-learning based detection technique, deformable part models(DPM)achieve great success in detecting complex object categories. The heavy computational burden of DPM,however, severely restricts their utilization in many real world applications. In this work, we accelerate DPM via parallelization and hypothesis pruning. Firstly,we implement the original DPM approach on a GPU platform and parallelize it, making it 136 times faster than DPM release 5 without loss of detection accuracy.Furthermore, we use a mixture root template as a prefilter for hypothesis pruning, and achieve more than 200 times speedup over DPM release 5, apparently the fastest implementation of DPM yet. The performance of our method has been validated on the Pascal VOC2007 and INRIA pedestrian datasets, and compared to other state-of-the-art techniques.展开更多
This paper’s simple ecological model to simulate the ecosystem variation and the vertical carbon flux in the central part of the East China Sea in spring, inter-reated the phytoplankton, zooplankton,autotrophic and h...This paper’s simple ecological model to simulate the ecosystem variation and the vertical carbon flux in the central part of the East China Sea in spring, inter-reated the phytoplankton, zooplankton,autotrophic and heterotrophic bacterioplankton, nitrate, and dissolved organic carbon (DOC) in a run lasting 90 days. Except for DOC, because of poor observation precision,the major seasonal features of the vertical distribution for these components can be simulated by this model. The results show that spring bloom is just a short period of 1-2 weeks and that deposit carbon flux at the bottom interface is about 200 mg /m2 ·d in the first 20 days and then reaches its maximum of 1500mg/m2·d about 2 months later after the spring bloom.展开更多
According to the current situation of repair and supply for valuable spare parts in the weapon equipment of the PLA,using the research results of the repairable spare parts inventory theory,an inventory model of the v...According to the current situation of repair and supply for valuable spare parts in the weapon equipment of the PLA,using the research results of the repairable spare parts inventory theory,an inventory model of the valuable spare parts in three-echelon repair and supply system is established by expanding the classical METRIC model and theory,and the genetic algorithm is utilized to solve the model.In the algorithm,the chromosome representation and initial population production,the crossover and mutation operators are designed.By using an example,a simulation analysis is carried out to verify the model's correctness.展开更多
The modeling and motion control of a universal part feeder is addressed. The feeder consists of a flat plate （or called bed） and a part placed on the plate. The bed can vibrate side-by-side （in x axis）, back and f...The modeling and motion control of a universal part feeder is addressed. The feeder consists of a flat plate （or called bed） and a part placed on the plate. The bed can vibrate side-by-side （in x axis）, back and forth （in y axis）, clockwise and counter clockwise （about z axis）, actuated by three linear motors （voice coils）. When the bed does these vibrations, the part placed on the plat will have position and/or orientation change due to the interaction between the two contact surfaces. By controlling the ways in which the plate vibrates, the position and orientation of the part can be controlled. The two vibration profiles of the bed are investigated in the research： the high-low vibration mode and the bang-bang vibration mode. The motion equations of the bed and the part as well as the control schemes for the high-low vibration mode are presented. Both simulation and real-time testing verify the system＇s dynamic model and indicate the feasibilities of the developed control laws.展开更多
The field of solid modeling has created numerous techniques for unambiguous computer representations of three-dimensional objects. Its data structures and algorithms have been used in a broad range of applications: Co...The field of solid modeling has created numerous techniques for unambiguous computer representations of three-dimensional objects. Its data structures and algorithms have been used in a broad range of applications: Computer-Aided Design and Computer-Aided Manufacturing (CAD/ CAM), robotics, computer vision, computer graphics and visualization, virtual reality, etc. This research paper is used to generate process plan from feature-based modeling, based on an integrated geometric modeling system that supports both feature-based modeling and information storage. Present system is developed only for milling components and limited to selective machining features for prismatic components and further implemented for more machining features to develop algorithms for modeling the components through the input of machining features. As a result, feature information is directly available to downstream activities, and feature extraction is no longer needed. The various systematic steps involved in this approach are study of Design, identification of Features, selection of Processes, Tools and Machines, Machining and Inspection [DFPTMMI]. Machining features generated in the design stage are recognized and stored under the Visual Basic control of CATIA software ActiveX interface. Algorithms are developed for individual features and these algorithms are embedded in Visual Basic forms. This system is discussed and suited for 2.5 Dimensional part approach, however, that can be extended to 3 dimensional prismatic part and complex features machining. Finally a process planning chart has been presented as a model process planning.展开更多
This article reports on the design and implementation of feature modelling system for the CAPP of rotational symmetric components. The work deals with design by features, feature parts database design, and parts infor...This article reports on the design and implementation of feature modelling system for the CAPP of rotational symmetric components. The work deals with design by features, feature parts database design, and parts information modelling techniques realized in Personal Computer. The modular software provides utilities such as interactive component synthesis, dimensioning, tolerancing and graphical display.展开更多
Taking high speed rotating shaft parts as the research object,the general fault mode of the parts is analyzed.The analysis process of shaft parts is expounded by means of finite element analysis method.A variety of fa...Taking high speed rotating shaft parts as the research object,the general fault mode of the parts is analyzed.The analysis process of shaft parts is expounded by means of finite element analysis method.A variety of fatigue life prediction methods for mechanical equipment parts are reviewed in this paper.And the selection and calculation method of parameters in the life prediction model of shaft parts are summarized.Finally,taking a gear shaft of a reducer as an example,the Morrow linear correction of the elastic stress model,Manson-Halford(M-H)correction model and Smith Watson Topper(SWT)correction model are applied to fatigue life assessments.The prediction results of the SWT correction model are relatively conservative.The prediction results of the Morrow linear correction of the elastic stress model and the M-H model are similar,and they are larger than the SWT correction model.展开更多
文摘Isothermal flashless die forging process of Ti - alloy structural air - frame part with varying thickness rib has been modelled in this paper.The results of present study show that a upside - down trapezoid rib would be formed and buckling would occure as blank is reduced,if the thickness of billet is maller than or equal to the thickness of rib. During modelling process of structural air frame part with E type cross - section rib, the saddle or lap would be formed finally at the middle of transverse rib between ribs with increase in deformation.If metal is allowed to flow out at confluence of longitudinal and transverse rib, the lop defect would be eliminated,, but a pipe cavity is obvious on corresponding loca- tion of blank. of defect formation depends on distance of metal flow ,friction,temperature homoge- neity of the blank and complexity of the part.
文摘In this paper, an EPQ-based inventory policy for an item is presented with stock-dependent demand during two trade credit periods. In addition, there is a provision for 1) an immediate part payment to the wholesaler, 2) borrowing some money from money lending source for the immediate part payment, 3) here supplier or wholesaler offers a trade credit period to his retailer and retailer also offers a trade credit period to his customer. Against the above conjectures inventory model has been formulated with respect to the retailer’s point of view for minimizing the total inventory cost. The non-linear optimization method-Generalized Reduced Gradient (GRG) method is used to find the optimal solutions. Lastly Numerical examples are set to illustrate this model. Finally we use LINGO software to solve this model.
基金supported by the National Natural Science Foundation of China (Nos. 61273285, 61375019)
文摘As a typical machine-learning based detection technique, deformable part models(DPM)achieve great success in detecting complex object categories. The heavy computational burden of DPM,however, severely restricts their utilization in many real world applications. In this work, we accelerate DPM via parallelization and hypothesis pruning. Firstly,we implement the original DPM approach on a GPU platform and parallelize it, making it 136 times faster than DPM release 5 without loss of detection accuracy.Furthermore, we use a mixture root template as a prefilter for hypothesis pruning, and achieve more than 200 times speedup over DPM release 5, apparently the fastest implementation of DPM yet. The performance of our method has been validated on the Pascal VOC2007 and INRIA pedestrian datasets, and compared to other state-of-the-art techniques.
文摘This paper’s simple ecological model to simulate the ecosystem variation and the vertical carbon flux in the central part of the East China Sea in spring, inter-reated the phytoplankton, zooplankton,autotrophic and heterotrophic bacterioplankton, nitrate, and dissolved organic carbon (DOC) in a run lasting 90 days. Except for DOC, because of poor observation precision,the major seasonal features of the vertical distribution for these components can be simulated by this model. The results show that spring bloom is just a short period of 1-2 weeks and that deposit carbon flux at the bottom interface is about 200 mg /m2 ·d in the first 20 days and then reaches its maximum of 1500mg/m2·d about 2 months later after the spring bloom.
基金Sponsored by the Foundation of National Defense Research(2008-76320)
文摘According to the current situation of repair and supply for valuable spare parts in the weapon equipment of the PLA,using the research results of the repairable spare parts inventory theory,an inventory model of the valuable spare parts in three-echelon repair and supply system is established by expanding the classical METRIC model and theory,and the genetic algorithm is utilized to solve the model.In the algorithm,the chromosome representation and initial population production,the crossover and mutation operators are designed.By using an example,a simulation analysis is carried out to verify the model's correctness.
文摘The modeling and motion control of a universal part feeder is addressed. The feeder consists of a flat plate （or called bed） and a part placed on the plate. The bed can vibrate side-by-side （in x axis）, back and forth （in y axis）, clockwise and counter clockwise （about z axis）, actuated by three linear motors （voice coils）. When the bed does these vibrations, the part placed on the plat will have position and/or orientation change due to the interaction between the two contact surfaces. By controlling the ways in which the plate vibrates, the position and orientation of the part can be controlled. The two vibration profiles of the bed are investigated in the research： the high-low vibration mode and the bang-bang vibration mode. The motion equations of the bed and the part as well as the control schemes for the high-low vibration mode are presented. Both simulation and real-time testing verify the system＇s dynamic model and indicate the feasibilities of the developed control laws.
文摘The field of solid modeling has created numerous techniques for unambiguous computer representations of three-dimensional objects. Its data structures and algorithms have been used in a broad range of applications: Computer-Aided Design and Computer-Aided Manufacturing (CAD/ CAM), robotics, computer vision, computer graphics and visualization, virtual reality, etc. This research paper is used to generate process plan from feature-based modeling, based on an integrated geometric modeling system that supports both feature-based modeling and information storage. Present system is developed only for milling components and limited to selective machining features for prismatic components and further implemented for more machining features to develop algorithms for modeling the components through the input of machining features. As a result, feature information is directly available to downstream activities, and feature extraction is no longer needed. The various systematic steps involved in this approach are study of Design, identification of Features, selection of Processes, Tools and Machines, Machining and Inspection [DFPTMMI]. Machining features generated in the design stage are recognized and stored under the Visual Basic control of CATIA software ActiveX interface. Algorithms are developed for individual features and these algorithms are embedded in Visual Basic forms. This system is discussed and suited for 2.5 Dimensional part approach, however, that can be extended to 3 dimensional prismatic part and complex features machining. Finally a process planning chart has been presented as a model process planning.
文摘This article reports on the design and implementation of feature modelling system for the CAPP of rotational symmetric components. The work deals with design by features, feature parts database design, and parts information modelling techniques realized in Personal Computer. The modular software provides utilities such as interactive component synthesis, dimensioning, tolerancing and graphical display.
基金National Natural Science Foundation of China(No.71761030)
文摘Taking high speed rotating shaft parts as the research object,the general fault mode of the parts is analyzed.The analysis process of shaft parts is expounded by means of finite element analysis method.A variety of fatigue life prediction methods for mechanical equipment parts are reviewed in this paper.And the selection and calculation method of parameters in the life prediction model of shaft parts are summarized.Finally,taking a gear shaft of a reducer as an example,the Morrow linear correction of the elastic stress model,Manson-Halford(M-H)correction model and Smith Watson Topper(SWT)correction model are applied to fatigue life assessments.The prediction results of the SWT correction model are relatively conservative.The prediction results of the Morrow linear correction of the elastic stress model and the M-H model are similar,and they are larger than the SWT correction model.
