In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Vi...In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Village of Xiqing District into 3 groups： compostable materials, recyclable materials and toxics on the basis of the constructed secondary classification mode of domestic waste. The study focused on waste generation strength and classification features, compared the waste generation features between rural and urban residents, and analyzed the re- lation between waste generation strength and economic and cultural factors. The re- sults indicated that the average generation speed of urban domestic waste was 423.08 g/（d.capita）, and that of rural domestic waste was 629.89 g/（d.capita）, there was significant difference between rural and urban compost generation strength （P= 0.00002）, while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference （P=0.471 and P=0.099, respec- tively）. Secondary classification mode is an effective source classification mode for domestic wastes and has positive effects on waste reduction and treatment.展开更多
Autonomous Underwater Vehicles(AUVs)are pivotal for deep-sea exploration and resource exploitation,yet their reliability in extreme underwater environments remains a critical barrier to widespread deployment.Through s...Autonomous Underwater Vehicles(AUVs)are pivotal for deep-sea exploration and resource exploitation,yet their reliability in extreme underwater environments remains a critical barrier to widespread deployment.Through systematic analysis of 150 peer-reviewed studies employing mixed-methods research,this review yields three principal advancements to the reliability analysis of AUVs.First,based on the hierarchical functional division of AUVs into six subsystems(propulsion system,navigation system,communication system,power system,environmental detection system,and emergency system),this study systematically identifies the primary failure modes and potential failure causes of each subsystem,providing theoretical support for fault diagnosis and reliability optimization.Subsequently,a comprehensive review of AUV reliability analysis methods is conducted from three perspectives:analytical methods,simulated methods,and surrogate model methods.The applicability and limitations of each method are critically analyzed to offer insights into their suitability for engineering applications.Finally,the study highlights key challenges and research hotpots in AUV reliability analysis,including reliability analysis under limited data,AI-driven reliability analysis,and human reliability analysis.Furthermore,the potential of multi-sensor data fusion,edge computing,and advanced materials in enhancing AUV environmental adaptability and reliability is explored.展开更多
This paper has announced the arrival of new economic era through an analysis of Nike＇s management mode. The traditional industry classification can＇t meet demands of industry development. We should inherit and impro...This paper has announced the arrival of new economic era through an analysis of Nike＇s management mode. The traditional industry classification can＇t meet demands of industry development. We should inherit and improve traditional economy in order to adapt to the development demand of new economy.展开更多
In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-...In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-uniformity degree of reservoir physical properties and the activity degree of peripheral water,respectively,based on the dual mechanism of water invasion to recharge the formation energy and seal off the gas in the reservoir.Then,the material balance method considering the phenomenon of water sealed gas was established.On this basis,the water invasion characteristic curve chart of water-bearing gas reservoirs was plotted,and the non-uniform water invasion mode was classified based on the example gas reservoir.And the following research results were obtained.First,in the water invasion characteristic curve chart of waterbearing gas reservoirs which is plotted based on the material balance method considering the influence of water sealed gas,the upper right area and the lower left area are defined as recharge area and seal area,respectively.By taking A=0 and B=2 as the boundary,the recharge area is divided into strong recharge area and weak recharge area.By taking A=2 and B=2 as the boundary,the seal area is divided into strong seal area and weak seal area.And correspondingly there are four water invasion modes,i.e.,strong recharge,weak recharge,weak seal and strong seal.Second,for fractured gas reservoirs,the non-uniformity degree of reservoir physical properties is high,and water sealed gas can be formed easily after water invasion.The dimensionless relative pseudo-pressure data of this type of gas reservoir is located in the seal area of the water invasion characteristic curve chart.Third,for the gas reservoirs whose reservoir physical properties are relatively uniform,the dimensionless relative pseudo-pressure data is located in the recharge area of the water invasion characteristic curve chart,and the recharge effect of water invasion on formation energy is greater than the weakening effect of water sealed gas on formation energy.Fourth,with the increase of A,the non-uniformity degree of reservoir physical properties increases,the water invasion characteristic curve shifts from the upper right to the lower left,and the recovery factor of gas reservoir decreases continuously.With the increase of B,the recharge effect of water invasion on formation energy and the weakening effect of water sealed gas on formation energy are both weakened,the distribution range of water invasion characteristic curve narrows to the recharge/seal boundary,and the corresponding range of gas reservoir recovery factor also narrows.展开更多
Before 1980s,the circular suspension spring in automobile subjected to torsion fatigue load,under the cyclic normal tensile stresses,the majority of fatigue fracture occurred was in normal tensile fracture mode（NTFM...Before 1980s,the circular suspension spring in automobile subjected to torsion fatigue load,under the cyclic normal tensile stresses,the majority of fatigue fracture occurred was in normal tensile fracture mode（NTFM）and the fracture surface was under 45°diagonal.Because there exists the interaction between the residual stresses induced by shot peening and the applied cyclic normal tensile stresses in NTFM,which represents as＂stress strengthening mechanism＂,shot peening technology could be used for improving the fatigue fracture resistance（FFR）of springs.However,since 1990s up to date,in addition to regular NTFM,the fatigue fractures occurred of peened springs from time to time are in longitudinal shear fracture mode（LSFM）or transverse shear fracture mode（TSFM）with the increase of applied cyclic shear stresses,which leads to a remarkable decrease of FFR.However,LSFM/TSFM can be avoided effectively by means of shot peening treatment again on the peened springs.The phenomena have been rarely happened before.At present there are few literatures concerning this problem.Based upon the results of force analysis of a spring,there is no interaction between the residual stresses by shot peening and the applied cyclic shear stresses in shear fracture.This;means that the effect of＂stress strengthening mechanism＂for improving the FFR of LSFM/TSFM is disappeared basically.During shot peening,however,both of residual stress and cyclic plastic deformed microstructure are induced synchronously like＂twins＂in the surface layer of a spring.It has been found for the first time by means of force analysis and experimental results that the modified microstructure in the＂twins＂as a＂structure strengthening mechanism＂can improve the FFR of LSFM/TSFM.At the same time,it is;also shown that the optimum technology of shot peening strengthening must have both＂stress strengthening mechanism＂and＂structure strengthening mechanism＂simultaneously so that the FFR of both NTFM and LSFM/TSFM can be improved by shot peening.展开更多
In this article,a new optimization system that uses few features to recognize locomotion with high classification accuracy is proposed.The optimization system consists of three parts.First,the features of the mixed me...In this article,a new optimization system that uses few features to recognize locomotion with high classification accuracy is proposed.The optimization system consists of three parts.First,the features of the mixed mechanical signal data are extracted from each analysis window of 200 ms after each foot contact event.Then,the Binary version of the hybrid Gray Wolf Optimization and Particle Swarm Optimization(BGWOPSO)algorithm is used to select features.And,the selected features are optimized and assigned different weights by the Biogeography-Based Optimization(BBO)algorithm.Finally,an improved K-Nearest Neighbor(KNN)classifier is employed for intention recognition.This classifier has the advantages of high accuracy,few parameters as well as low memory burden.Based on data from eight patients with transfemoral amputations,the optimization system is evaluated.The numerical results indicate that the proposed model can recognize nine daily locomotion modes(i.e.,low-,mid-,and fast-speed level-ground walking,ramp ascent/decent,stair ascent/descent,and sit/stand)by only seven features,with an accuracy of 96.66%±0.68%.As for real-time prediction on a powered knee prosthesis,the shortest prediction time is only 9.8 ms.These promising results reveal the potential of intention recognition based on the proposed system for high-level control of the prosthetic knee.展开更多
A low-voltage ride-through(LVRT)control strategy for the multi-port power electronic transformer(PET)based on power co-regulation is proposed.During the sag and recovery of the grid-side voltage of the medium-voltage ...A low-voltage ride-through(LVRT)control strategy for the multi-port power electronic transformer(PET)based on power co-regulation is proposed.During the sag and recovery of the grid-side voltage of the medium-voltage ac(MVac)port,the grid-connected active power of the low-voltage ac(LVac)port,rather than the power from external renewable energy sources(e.g.,photovoltaic(PV)),is adjusted quickly to rebalance the power flowing across all ports,thereby preventing overcurrent and overvoltage.Moreover,a power-coordinate-frame-based LVRT mode classification is designed,and a total of six LVRT modes are classified to meet the LVRT requirements in all power configuration scenarios of the PET.In this way,the PET is endowed with the LVRT capability in both power-generation and power-consumption states,which is significantly different from traditional power generation systems such as PV or wind power.Furthermore,by optimizing the active power regulation path during LVRT transition,the overcurrent problem caused by the grid-voltage sag-depth detection delay is overcome.Finally,the effectiveness of the proposed control scheme is verified by experiments on a hardware-in-the-loop platform.展开更多
基金Supported by Agricultural Scientific and Technological Achievement Transformation and Popularization Project of Tianjin(201003010)~~
文摘In order to investigate the influence of secondary classification mode on waste generation features, this study classified domestic waste generated by 310 rural and urban households at urban areas and Shuigaozhuang Village of Xiqing District into 3 groups： compostable materials, recyclable materials and toxics on the basis of the constructed secondary classification mode of domestic waste. The study focused on waste generation strength and classification features, compared the waste generation features between rural and urban residents, and analyzed the re- lation between waste generation strength and economic and cultural factors. The re- sults indicated that the average generation speed of urban domestic waste was 423.08 g/（d.capita）, and that of rural domestic waste was 629.89 g/（d.capita）, there was significant difference between rural and urban compost generation strength （P= 0.00002）, while the generation strength of recyclable materials and toxics between rural and urban areas had no significant difference （P=0.471 and P=0.099, respec- tively）. Secondary classification mode is an effective source classification mode for domestic wastes and has positive effects on waste reduction and treatment.
基金The National Key R&D Program Projects(Grant No.2022YFC2803601)the Natural Science Foundation of Shandong Province(Grant No.ZR2021YQ29)+1 种基金the Natural Science Foundation of Heilongjiang Province(Grant No.YQ2024E036)the Taishan Scholars Project(Grant No.tsqn202312317).
文摘Autonomous Underwater Vehicles(AUVs)are pivotal for deep-sea exploration and resource exploitation,yet their reliability in extreme underwater environments remains a critical barrier to widespread deployment.Through systematic analysis of 150 peer-reviewed studies employing mixed-methods research,this review yields three principal advancements to the reliability analysis of AUVs.First,based on the hierarchical functional division of AUVs into six subsystems(propulsion system,navigation system,communication system,power system,environmental detection system,and emergency system),this study systematically identifies the primary failure modes and potential failure causes of each subsystem,providing theoretical support for fault diagnosis and reliability optimization.Subsequently,a comprehensive review of AUV reliability analysis methods is conducted from three perspectives:analytical methods,simulated methods,and surrogate model methods.The applicability and limitations of each method are critically analyzed to offer insights into their suitability for engineering applications.Finally,the study highlights key challenges and research hotpots in AUV reliability analysis,including reliability analysis under limited data,AI-driven reliability analysis,and human reliability analysis.Furthermore,the potential of multi-sensor data fusion,edge computing,and advanced materials in enhancing AUV environmental adaptability and reliability is explored.
文摘This paper has announced the arrival of new economic era through an analysis of Nike＇s management mode. The traditional industry classification can＇t meet demands of industry development. We should inherit and improve traditional economy in order to adapt to the development demand of new economy.
基金Project supported by the PetroChina-SWPU Innovation Alliance's technological cooperation project(No.2020CX010402).
文摘In order to clarify the characteristics of non-uniform water invasion in water-bearing gas reservoirs,it is necessary to introduce the nonuniformity coefficient(A)and water invasion constant(B)to characterize the non-uniformity degree of reservoir physical properties and the activity degree of peripheral water,respectively,based on the dual mechanism of water invasion to recharge the formation energy and seal off the gas in the reservoir.Then,the material balance method considering the phenomenon of water sealed gas was established.On this basis,the water invasion characteristic curve chart of water-bearing gas reservoirs was plotted,and the non-uniform water invasion mode was classified based on the example gas reservoir.And the following research results were obtained.First,in the water invasion characteristic curve chart of waterbearing gas reservoirs which is plotted based on the material balance method considering the influence of water sealed gas,the upper right area and the lower left area are defined as recharge area and seal area,respectively.By taking A=0 and B=2 as the boundary,the recharge area is divided into strong recharge area and weak recharge area.By taking A=2 and B=2 as the boundary,the seal area is divided into strong seal area and weak seal area.And correspondingly there are four water invasion modes,i.e.,strong recharge,weak recharge,weak seal and strong seal.Second,for fractured gas reservoirs,the non-uniformity degree of reservoir physical properties is high,and water sealed gas can be formed easily after water invasion.The dimensionless relative pseudo-pressure data of this type of gas reservoir is located in the seal area of the water invasion characteristic curve chart.Third,for the gas reservoirs whose reservoir physical properties are relatively uniform,the dimensionless relative pseudo-pressure data is located in the recharge area of the water invasion characteristic curve chart,and the recharge effect of water invasion on formation energy is greater than the weakening effect of water sealed gas on formation energy.Fourth,with the increase of A,the non-uniformity degree of reservoir physical properties increases,the water invasion characteristic curve shifts from the upper right to the lower left,and the recovery factor of gas reservoir decreases continuously.With the increase of B,the recharge effect of water invasion on formation energy and the weakening effect of water sealed gas on formation energy are both weakened,the distribution range of water invasion characteristic curve narrows to the recharge/seal boundary,and the corresponding range of gas reservoir recovery factor also narrows.
文摘Before 1980s,the circular suspension spring in automobile subjected to torsion fatigue load,under the cyclic normal tensile stresses,the majority of fatigue fracture occurred was in normal tensile fracture mode（NTFM）and the fracture surface was under 45°diagonal.Because there exists the interaction between the residual stresses induced by shot peening and the applied cyclic normal tensile stresses in NTFM,which represents as＂stress strengthening mechanism＂,shot peening technology could be used for improving the fatigue fracture resistance（FFR）of springs.However,since 1990s up to date,in addition to regular NTFM,the fatigue fractures occurred of peened springs from time to time are in longitudinal shear fracture mode（LSFM）or transverse shear fracture mode（TSFM）with the increase of applied cyclic shear stresses,which leads to a remarkable decrease of FFR.However,LSFM/TSFM can be avoided effectively by means of shot peening treatment again on the peened springs.The phenomena have been rarely happened before.At present there are few literatures concerning this problem.Based upon the results of force analysis of a spring,there is no interaction between the residual stresses by shot peening and the applied cyclic shear stresses in shear fracture.This;means that the effect of＂stress strengthening mechanism＂for improving the FFR of LSFM/TSFM is disappeared basically.During shot peening,however,both of residual stress and cyclic plastic deformed microstructure are induced synchronously like＂twins＂in the surface layer of a spring.It has been found for the first time by means of force analysis and experimental results that the modified microstructure in the＂twins＂as a＂structure strengthening mechanism＂can improve the FFR of LSFM/TSFM.At the same time,it is;also shown that the optimum technology of shot peening strengthening must have both＂stress strengthening mechanism＂and＂structure strengthening mechanism＂simultaneously so that the FFR of both NTFM and LSFM/TSFM can be improved by shot peening.
基金This research was supported in part by the National Key Research and Development Program of China under Grant 2018YFC2001300in part by the National Natural Science Foundation of China under Grant 91948302,Grant 91848204,and Grant 52021003the Project of Scientific and Technological Development Plan of Jilin Province under Grant 20220508130RC.
文摘In this article,a new optimization system that uses few features to recognize locomotion with high classification accuracy is proposed.The optimization system consists of three parts.First,the features of the mixed mechanical signal data are extracted from each analysis window of 200 ms after each foot contact event.Then,the Binary version of the hybrid Gray Wolf Optimization and Particle Swarm Optimization(BGWOPSO)algorithm is used to select features.And,the selected features are optimized and assigned different weights by the Biogeography-Based Optimization(BBO)algorithm.Finally,an improved K-Nearest Neighbor(KNN)classifier is employed for intention recognition.This classifier has the advantages of high accuracy,few parameters as well as low memory burden.Based on data from eight patients with transfemoral amputations,the optimization system is evaluated.The numerical results indicate that the proposed model can recognize nine daily locomotion modes(i.e.,low-,mid-,and fast-speed level-ground walking,ramp ascent/decent,stair ascent/descent,and sit/stand)by only seven features,with an accuracy of 96.66%±0.68%.As for real-time prediction on a powered knee prosthesis,the shortest prediction time is only 9.8 ms.These promising results reveal the potential of intention recognition based on the proposed system for high-level control of the prosthetic knee.
基金supported by the National Nature Science Foundation of China(Grant No.U2034201)the key project of Science and Technology Innovation Program of Army Engineering Uni-versity(Grant No.KYCQJQZL2119)。
文摘A low-voltage ride-through(LVRT)control strategy for the multi-port power electronic transformer(PET)based on power co-regulation is proposed.During the sag and recovery of the grid-side voltage of the medium-voltage ac(MVac)port,the grid-connected active power of the low-voltage ac(LVac)port,rather than the power from external renewable energy sources(e.g.,photovoltaic(PV)),is adjusted quickly to rebalance the power flowing across all ports,thereby preventing overcurrent and overvoltage.Moreover,a power-coordinate-frame-based LVRT mode classification is designed,and a total of six LVRT modes are classified to meet the LVRT requirements in all power configuration scenarios of the PET.In this way,the PET is endowed with the LVRT capability in both power-generation and power-consumption states,which is significantly different from traditional power generation systems such as PV or wind power.Furthermore,by optimizing the active power regulation path during LVRT transition,the overcurrent problem caused by the grid-voltage sag-depth detection delay is overcome.Finally,the effectiveness of the proposed control scheme is verified by experiments on a hardware-in-the-loop platform.
