Unsupervised and supervised pattern recognition( PR)techniques are used to classify the acoustic emission( AE) data originating from the quasi-isotropic self-reinforced polyethylene composites,in order to identify the...Unsupervised and supervised pattern recognition( PR)techniques are used to classify the acoustic emission( AE) data originating from the quasi-isotropic self-reinforced polyethylene composites,in order to identify the various mechanisms in the multiangle-ply thermoplastic composites. Ultra-high molecular weight polyethylene / low density polyethylene( UHMWPE / LDPE)composites were made and tested under quasi-static tensile load. The failure process was monitored by the AE technique. The collected AE signals were classified by unsupervised and supervised PR techniques, respectively. AE signals were clustered with unsupervised PR scheme automatically and mathematically. While in the supervised PR scheme,the labeled AE data from simple lay-up UHMWPE / LDPE laminates were utilized as the reference data.Comparison was drawn according to the analytical results. Fracture surfaces of the UHMWPE / LDPE specimens were observed by a scanning electron microscope( SEM) for some physical support. By combining both classification results with the observation results,correlations were established between the AE signal classes and their originating damage modes. The comparison between the two classifying schemes showed a good agreement in the main damage modes and their failure process. It indicates both PR techniques are powerful for the complicated thermoplastic composites. Supervised PR scheme can lead to a more precise classification in that a suitable reference data set is input.展开更多
Modern ecological breeding has the characteristics of protecting the ecological environment,health,nutrition,delicious,and so on.In the ecological breeding of traditional breeding chicken,using non antibiotic breeding...Modern ecological breeding has the characteristics of protecting the ecological environment,health,nutrition,delicious,and so on.In the ecological breeding of traditional breeding chicken,using non antibiotic breeding,traditional Chinese medicine and other breeding technologies can not only obtain green,non-harmful and safe food products,but also reduce the cost of farmers and provide breeding efficiency This is a sustainable development path.This paper gave a brief overview of this field.展开更多
Piezoelectric-driven stick slip actuators have been drawn more and more attention in the nano- positioning application due to the high accuracy and theoretical unlimited displacement. However, the hysteresis of piezoe...Piezoelectric-driven stick slip actuators have been drawn more and more attention in the nano- positioning application due to the high accuracy and theoretical unlimited displacement. However, the hysteresis of piezoelectric actuator (PEA) and the nonlinear friction force between the end- effector and the stage make control of piezoelectric-driven stick slip actuator challenge. This paper presents the development of an autoregressive exogenous (ARX)-based proportional-integral-derive (PID)-sliding mode control (SMC) for the velocity tracking control of the piezoelectric-driven stick slip actuator. Stability is guaranteed by rigorously choosing the appropriate PID parameters and the zero steady state error is achieved. To verify the effectiveness of the proposed method, experiments were carried out on a commercially-available piezoelectric-driven stick slip actuator. The tracking errors were compared with the traditional PID controller, illustrating that in spite of existing of modeling error, the ARX-based PID-SMC is able to better improve the velocity tracking performance of piezoelectric-driven stick slip actuator, compared with the traditional PID controller.展开更多
In China, currently there are more than 100 million videos being watched everyday on the Internet. There are three kinds of Internet videos: video sharing, Video on Demand (VoD), and Peer-to-Peer (P2P) streaming media...In China, currently there are more than 100 million videos being watched everyday on the Internet. There are three kinds of Internet videos: video sharing, Video on Demand (VoD), and Peer-to-Peer (P2P) streaming media. Video sharing is based on browser/server mode, severing user generated content. VoD is based on client/server mode and needs to be paid for. P2P streaming media is based on P2P mode service for hot content. To address P2P traffic optimization and content regulation, China National Information Technology Standardization Technical Committee sets up P2P working group to make relevant standards.展开更多
● Power tariffreform has made many important and substantialprogresses in respect ofmarketization● The benchmark tariff is a revolutionary progress made in China's power tariff reform● Coal-electricity price li...● Power tariffreform has made many important and substantialprogresses in respect ofmarketization● The benchmark tariff is a revolutionary progress made in China's power tariff reform● Coal-electricity price linkage is a transitional approach which needs further improvement● The principle of T&D pricing is "cost plus profit," but it can also be based on pro rata control● China's electricity market should choose the mode of bilateral contracting combined withcentralized market● The direction of the power tariff reform is that electricity price shall be controlled mainly by the re-lationship between supply and demand in the展开更多
基金Scientific Research Foundation of Guangdong Polytechnic,China(No.K2010201)
文摘Unsupervised and supervised pattern recognition( PR)techniques are used to classify the acoustic emission( AE) data originating from the quasi-isotropic self-reinforced polyethylene composites,in order to identify the various mechanisms in the multiangle-ply thermoplastic composites. Ultra-high molecular weight polyethylene / low density polyethylene( UHMWPE / LDPE)composites were made and tested under quasi-static tensile load. The failure process was monitored by the AE technique. The collected AE signals were classified by unsupervised and supervised PR techniques, respectively. AE signals were clustered with unsupervised PR scheme automatically and mathematically. While in the supervised PR scheme,the labeled AE data from simple lay-up UHMWPE / LDPE laminates were utilized as the reference data.Comparison was drawn according to the analytical results. Fracture surfaces of the UHMWPE / LDPE specimens were observed by a scanning electron microscope( SEM) for some physical support. By combining both classification results with the observation results,correlations were established between the AE signal classes and their originating damage modes. The comparison between the two classifying schemes showed a good agreement in the main damage modes and their failure process. It indicates both PR techniques are powerful for the complicated thermoplastic composites. Supervised PR scheme can lead to a more precise classification in that a suitable reference data set is input.
基金Supported by International Science and Technology Innovation Cooperation Project of Sichuan Province(2020YFH0202)Key Research and Development Project of Science and Technology Plan of Liangshan Prefecture(20ZDYF0002)。
文摘Modern ecological breeding has the characteristics of protecting the ecological environment,health,nutrition,delicious,and so on.In the ecological breeding of traditional breeding chicken,using non antibiotic breeding,traditional Chinese medicine and other breeding technologies can not only obtain green,non-harmful and safe food products,but also reduce the cost of farmers and provide breeding efficiency This is a sustainable development path.This paper gave a brief overview of this field.
文摘Piezoelectric-driven stick slip actuators have been drawn more and more attention in the nano- positioning application due to the high accuracy and theoretical unlimited displacement. However, the hysteresis of piezoelectric actuator (PEA) and the nonlinear friction force between the end- effector and the stage make control of piezoelectric-driven stick slip actuator challenge. This paper presents the development of an autoregressive exogenous (ARX)-based proportional-integral-derive (PID)-sliding mode control (SMC) for the velocity tracking control of the piezoelectric-driven stick slip actuator. Stability is guaranteed by rigorously choosing the appropriate PID parameters and the zero steady state error is achieved. To verify the effectiveness of the proposed method, experiments were carried out on a commercially-available piezoelectric-driven stick slip actuator. The tracking errors were compared with the traditional PID controller, illustrating that in spite of existing of modeling error, the ARX-based PID-SMC is able to better improve the velocity tracking performance of piezoelectric-driven stick slip actuator, compared with the traditional PID controller.
文摘In China, currently there are more than 100 million videos being watched everyday on the Internet. There are three kinds of Internet videos: video sharing, Video on Demand (VoD), and Peer-to-Peer (P2P) streaming media. Video sharing is based on browser/server mode, severing user generated content. VoD is based on client/server mode and needs to be paid for. P2P streaming media is based on P2P mode service for hot content. To address P2P traffic optimization and content regulation, China National Information Technology Standardization Technical Committee sets up P2P working group to make relevant standards.
文摘● Power tariffreform has made many important and substantialprogresses in respect ofmarketization● The benchmark tariff is a revolutionary progress made in China's power tariff reform● Coal-electricity price linkage is a transitional approach which needs further improvement● The principle of T&D pricing is "cost plus profit," but it can also be based on pro rata control● China's electricity market should choose the mode of bilateral contracting combined withcentralized market● The direction of the power tariff reform is that electricity price shall be controlled mainly by the re-lationship between supply and demand in the
