The Songliao Basin in northeast China is one of the largest petroliferous basins worldwide,and features the T_(2)fault system,which consists of numerous minor extensional normal faults.This study combines high-resolut...The Songliao Basin in northeast China is one of the largest petroliferous basins worldwide,and features the T_(2)fault system,which consists of numerous minor extensional normal faults.This study combines high-resolution 3D seismic datasets to detail the characteristics of the T_(2)fault system,contributing two key findings:(1)The T_(2)faults are confirmed as polygonal fault systems,characterized by closely spaced,layer-bounded faults with small throws,high dip angles,and random orientations,forming intricate polygonal networks.(2)The study reveals the influence of tectonic stresses on the fault system,showing spatial variations across different tectonic units.In depressions,T_(2)faults exhibit short lengths,small throws,high density,and multiple directions.In contrast,in inverted anticline belts,they have longer lengths,bigger throws,higher density,and concordant orientations.These variations demonstrate the impact of tectonic inversion on the development of T_(2)faults.The significance of this research lies in presenting a typical polygonal fault system developed in a deep lake succession and was superposed the influence by regional tectonic stress coeval with its development.The new insights facilitate a reevaluation of the T_(2)fault system's role in hydrocarbon migration and accumulation within the Songliao Basin.展开更多
The electric vertical takeoff and landing(e VTOL)aircraft shows great potential for rapid military personnel deployment on the battlefield.However,its susceptibility to control loss,complex crashes,and extremely limit...The electric vertical takeoff and landing(e VTOL)aircraft shows great potential for rapid military personnel deployment on the battlefield.However,its susceptibility to control loss,complex crashes,and extremely limited bottom energy-absorbing space demands higher comprehensive crashworthiness of its subfloor thin-walled structures.This study investigated the energy absorption capacity of novel concave polygonal carbon fiber reinforced plastics(CFRP)tubes under multi-angle collisions.Quasistatic compression experiments and finite element simulations were conducted to assess the failure mode and energy absorption.The influences of cross-section shapes,loading conditions,and geometry parameters on crashworthiness metrics were further analyzed.The results revealed that,under the similar weight,concave polygonal tubes exhibited superior energy absorption under axial loads compared to regular polygonal and circular tubes,attributed to the increased number of axial splits.However,both regular and concave polygonal tubes,particularly the latter,demonstrated reduced oblique energy absorption compared to traditional square tubes with the increasing ratio of SEA value decreased from 20%-16%.Notably,this reduction in energy absorption can be compensated for by the implementation of inward and outward crusher plugs,and with them,the concave polygonal tubes demonstrated outstanding overall crashworthiness performance under multiple loading conditions.This concave cross-sectional design methods could serve as a guidance for the development of the eVTOL subfloor.展开更多
Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail med...Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external excitations.In this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented.Further,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed.The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails.Execution of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal wear.This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.展开更多
The study on the entanglement polygon inequality of multipartite systems has attracted much attention.However,most of the results are on pure states.Here we consider the property for a class of mixed states,which are ...The study on the entanglement polygon inequality of multipartite systems has attracted much attention.However,most of the results are on pure states.Here we consider the property for a class of mixed states,which are the reduced density matrices of generalizedW-class states in multipartite higher dimensional systems.First we show the class of mixed states satisfies the entanglement polygon inequalities in terms of Tsallis-q entanglement,then we propose a class of tighter inequalities for mixed states in terms of Tsallis-q entanglement.At last,we get an inequality for the mixed states,which can be regarded as a relation for bipartite entanglement.展开更多
The dynamic load distribution within in-service axlebox bearings of high-speed trains is crucial for the fatigue reliability assessment and forward design of axlebox bearings. This paper presents an in situ measuremen...The dynamic load distribution within in-service axlebox bearings of high-speed trains is crucial for the fatigue reliability assessment and forward design of axlebox bearings. This paper presents an in situ measurement of the dynamic load distribution in the four rows of two axlebox bearings on a bogie wheelset of a high-speed train under polygonal wheel–rail excitation. The measurement employed an improved strain-based method to measure the dynamic radial load distribution of roller bearings. The four rows of two axlebox bearings on a wheelset exhibited different ranges of loaded zones and different means of distributed loads. Besides, the mean value and standard deviation of measured roller–raceway contact loads showed non-monotonic variations with the frequency of wheel–rail excitation. The fatigue life of the four bearing rows under polygonal wheel–rail excitation was quantitatively predicted by compiling the measured roller–raceway contact load spectra of the most loaded position and considering the load spectra as input.展开更多
Purpose–This study aims to investigate the cause of high-order wheel polygonization in a plateau high-speed electric multiple unit(EMU)train.Design/methodology/approach–A series of field tests were conducted to meas...Purpose–This study aims to investigate the cause of high-order wheel polygonization in a plateau high-speed electric multiple unit(EMU)train.Design/methodology/approach–A series of field tests were conducted to measure the vibration accelerations of the axle box and bogie when the wheels of the EMU train passed through tracks with normal rail roughness after re-profiling.Additionally,the dynamic characteristics of the track,wheelset and bogie were also measured.These measurements provided insights into the mechanisms that lead to wheel polygonization.Findings–The results of the field tests indicate that wheel polygonal wear in theEMUtrain primarily exhibits 14–16 and 25–27 harmonic orders.The passing frequencies of wheel polygonization were approximately 283–323 Hz and 505–545 Hz,which closely match the dominated frequencies of axle box and bogie vibrations.These findings suggest that the fixed-frequency vibrations originate from the natural modes of the wheelset and bogie,which can be excited by wheel/rail irregularities.Originality/value–The study provides novel insights into the mechanisms of high-order wheel polygonization in plateau high-speed EMU trains.Futher,the results indicate that operating the EMU train on mixed lines at variable speeds could potentially mitigate high-order polygonal wear,providing practical value for improving the safety,performance and maintenance efficiency of high-speed EMU trains.展开更多
An algorithm for partitioning arbitrary simple polygons into a number of convex parts was presented. The concave vertices were determined first, and then they were moved by using the method connecting the concave vert...An algorithm for partitioning arbitrary simple polygons into a number of convex parts was presented. The concave vertices were determined first, and then they were moved by using the method connecting the concave vertices with the vertices of falling into its region B,so that the primary polygon could be partitioned into two subpolygons. Finally, this method was applied recursively to the subpolygons until all the concave vertices were removed. This algorithm partitions the polygon into O(l) convex parts, its time complexity is max(O(n),O(l 2)) multiplications, where n is the number of vertices of the polygon and l is the number of the concave vertices.展开更多
When studying the regular polygonal inclusion in 1997, Nozaki and Taya discovered numerically some remarkable properties of Eshelby tensor： Eshelby tensor at the center and the averaged Eshelby tensor over the inclus...When studying the regular polygonal inclusion in 1997, Nozaki and Taya discovered numerically some remarkable properties of Eshelby tensor： Eshelby tensor at the center and the averaged Eshelby tensor over the inclusion domain are equal to that of a circular inclusion and independent of the orientation of the inclusion. Then Kawashita and Nozaki justified the properties mathematically. In the present paper, some other properties of a regular polygonal inclusion are discovered. We find that for an N-fold regular polygonal inclusion except for a square, the arithmetic mean of Eshelby tensors at N rotational symmetrical points in the inclusion is also equal to the Eshelby tensor for a circular inclusion and independent of the orientation of the inclusion. Furthermore, in two corollaries, we point out that Eshelby tensor at the center, the averaged Eshelby tensor over the inclusion domain, and the line integral average of Eshelby tensors along any concentric circle of the inclusion are all identical with the arithmetic mean.展开更多
The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric pr...The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric principle. With the use of differential geometry theory, the curve is proved to be with geometric feature of convex curve. It is referred to as Isometric Polygonal Curve (IPC), because that is a kind of convex curve on which the distance between any parallel tangent lines is equal. Isometric Polygonal Profile (IPP) or Isometric Polygonal Cone Profile (IPCP) or Isometric Polygonal Topless Cone (IPTC) is formed with the IPC and straight line as generating curve. But the machining and measuring of the IPCP are so inconvenient that it has little value. Keeping in mind the characteristic of the IPP and IPTC, this paper puts forward the program method of CNC grinding machining. Isometric polygonal profile connection is a kind of polygonal profile connection. It has the superiority over keys (prismatic key & spline etc), and can be suit for the situations such as high rotative velocity, large torque, high precision, and small fixed room and vibration. Nowadays, some countries such as America, Russia, German and Switzerland applied CNC machining to the machining of polygon surface coupling parts, which makes their applications in machine productions such as motor engine, heavy machine increase day by day. But reports about concrete machining technology of isometric polygonal profile and programming of CNC machining program are very few. CNC grinding of the IPP and IPTC is one kind of the precision machining technology. It is of great importance to the popularization of the IPP and IPTC connection. From the forming mechanism, we can see that the machining and measuring of the IPP and IPTC are convenient, and therefore they have the value of the popularization. But the machining and measuring of the IPCP are so inconvenient that it has little value. In the programming the CNC grinding of the IPP and IPTC, it is more reasonable to calculate the coordinate of node according to the approaching method of equal error arc. According to the method of CNC grinding mentioned above to design the grinding machine, the structure is simple and of economical and practical.展开更多
A new method for point-polygon classification is presented in the paper. The basic idea of the method is first advanced and then two properties of polygon are introduced. The criterions for point-polygon classificatio...A new method for point-polygon classification is presented in the paper. The basic idea of the method is first advanced and then two properties of polygon are introduced. The criterions for point-polygon classification are given explicitly. The analysis shows that the possesses perfect function, extensive suitability and high efficiency.展开更多
This paper presents a detailed investigation, via field experiment, into the mechanism of high-order polygonal wear of wheels of a new type of high-speed train. The investigation was carried out during the performance...This paper presents a detailed investigation, via field experiment, into the mechanism of high-order polygonal wear of wheels of a new type of high-speed train. The investigation was carried out during the performance acceptance test of the train and its initial commercial operation. The investigation covered the performance acceptance test of 150 000 km and the commercial operation of about 150 000 km. In the performance acceptance test of the first stage of about 70 000 km, at 200-250 km/h with full loading and sometimes overloading by 30%, the serious polygonal wear of 23-order took place on all the wheels of the train, and was measured and analyzed in detail. All the potygonized wheels were re-profiled because the polygonal wear had caused strong vibration and damage to the train parts. After re-profiling, the vibration of the train and track and the wear status of the wheels were measured and analyzed at different test mileages according to the polygonal wear situation of the wheels. The measured vibration of the train includes the accelerations at different positions of a motor car and a trail car. The vibration modes of the key parts of the bogies of the two cars were calculated. Meanwhile, the track resonant frequencies were investigated at the site. The purpose of the above tests and analysis is try to find the frequency of work mode matching the passing frequency of the high-order wheel polygon. The present investigation shows that one of the working models causes the formation and development of the high-order wheel polygonal wear. The growth of this wear was effectively reduced through the frequent changing of the running speed of the train operating on the way back and forth every day.展开更多
Based on high-resolution 3D seismic data, we document the polygonal faults within the Miocene Meishan （梅山） Formation and Huangliu （黄流） Formation of the Qiongdongnan （琼东南） basin, northern South China Sea. ...Based on high-resolution 3D seismic data, we document the polygonal faults within the Miocene Meishan （梅山） Formation and Huangliu （黄流） Formation of the Qiongdongnan （琼东南） basin, northern South China Sea. Within the seismic section and time coherent slice, densely distributed extensional faults with small throw and polygonal shape were identified in map view. The orientation of the polygonal faults is almost isotropic, indicating a non-tectonic origin. The deformation is clearly layer-bounded, with horizontal extension of 11.2% to 16%, and 13.2% on average. The distribution of polygonal faults shows a negative correlation with that of gas chimneys. The development of polygonal faults may be triggered by over-pressure pore fluid which is restricted in the fine-grained sediments of bathyal facies when the sediments is compacted by the burden above. The polygonal faults developed to balance the volumetric contraction and restricted extension. The product of hydrocarbon in the Meishan Formation may have contributed to the development of the polygonal faults. In the study area, it was thought that the petroleum system of the Neogene post-rift sequence is disadvantageous because of poor migration pathway. However, the discovery of polygonal faults in the Miocene strata, which may play an important role on the fluid migration, may change this view. A new model of the petroleum system for the study area is proposed.展开更多
Voronoi diagram is founded by using computational geometry based on originaldistribution of the waypoints, and then the elements from Voronoi diagram are metamorphosed by usingthe rule for airsppce partition, and the ...Voronoi diagram is founded by using computational geometry based on originaldistribution of the waypoints, and then the elements from Voronoi diagram are metamorphosed by usingthe rule for airsppce partition, and the controller's workload is accounted in each element that ismade up of Metamorphic Voronoi polygon. Then in accordance with the rule about balance ofcontroller's workload, Simulated Annealing algorithm (SA) is used to achieve the optimization ofcombination of those elements , and the new resolution has satisfied the restriction of two rulesfor airspace partition. Therefore, the boundaries of the aggregates of these elements are theoptimal borderlines of sectors. The result of actual airspace design example validates therationality of the sector optimization method presented in this paper.展开更多
Based on the deformation characteristic of regular polygonal box stamped parts and the superfluous triangle material wrinkle model,the criterion of regular polygonal box stamped parts without wrinkle was deduced and u...Based on the deformation characteristic of regular polygonal box stamped parts and the superfluous triangle material wrinkle model,the criterion of regular polygonal box stamped parts without wrinkle was deduced and used to predict and control the wrinkle limit.According to the fracture model,the criterion of regular polygonal box stamped parts without fracture was deduced and used to predict and control the fracture limit.Combining the criterion for stamping without wrinkle with that without fracture,the stamping criterion of regular polygonal box stamped parts was obtained to predict and control the stamping limit.Taken the stainless steel0Cr18Ni9(SUS304)sheet and the square box stamped part as examples,the limit diagram was given to predict and control the wrinkle,fracture and stamping limits.It is suitable for the deep drawing without flange,the deep drawing and stretching combined forming with flange and the rigid punch stretching of plane blank.The limit deep-drawing coefficient and the minimum deep-drawing coefficient can be determined,and the appropriate BHF(blank holder force)and the deep-drawing force can be chosen.These provide a reference for the technology planning,the die and mold design and the equipment determination,and a new criterion evaluating sheet stamping formability,which predicts and controls the stamping process,can be applied to the deep drawing under constant or variable BHF conditions.展开更多
Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take ...Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take all polygons of the same map unit on a map as a whole to extract the soil–environment relationship.Such approach ignores the difference in the environmental conditions represented by individual soil polygons of the same map unit.This paper proposes a method of mining soil–environment relationships from individual soil polygons to update conventional soil maps.The proposed method consists of three major steps.Firstly,the soil–environment relationships represented by each individual polygon on a conventional soil map are extracted in the form of frequency distribution curves for the involved environmental covariates.Secondly,for each environmental covariate,these frequency distribution curves from individual polygons of the same soil map unit are synthesized to form the overall soil–environment relationship for that soil map unit across the mapped area.And lastly,the extracted soil–environment relationships are applied to updating the conventional soil map with new,improved environmental data by adopting a soil land inference model(SoLIM)framework.This study applied the proposed method to updating a conventional soil map of the Raffelson watershed in La Crosse County,Wisconsin,United States.The result from the proposed method was compared with that from the previous method of taking all polygons within the same soil map unit on a map as a whole.Evaluation results with independent soil samples showed that the proposed method exhibited better performance and produced higher accuracy.展开更多
Over 600 chloride-bearing deposits(chlorides) have been identified on the southern highlands of Mars. These chlorides have critical implications for hydrology and astrobiology: they are indicators of an evaporating su...Over 600 chloride-bearing deposits(chlorides) have been identified on the southern highlands of Mars. These chlorides have critical implications for hydrology and astrobiology: they are indicators of an evaporating super saturated solution, and they could have provided habitat environments for halophilic microorganisms and preserved organic matter. One of the prominent geomorphology characteristics of these chloridebearing regions is the polygonal features within them. The origin of these polygonal features is still in debate. In this study, we have surveyed 153 locations of chlorides using 441 high resolution imaging science experiment(Hi RISE) images to characterize the geomorphology of polygonal features. We identified 3 types of polygonal features of distinct geomorphologic characteristics: fractures, raised ridges, and transitional polygons between fractures and raised ridges. We evaluate previously proposed hypotheses of the formation of the polygonal features, and suggest that the 3 types of polygonal features are indicators of different stages of salt crust formation. Salt crust is usually formed through multiple groundwater activities, and it often occurs in playa environment on Earth. The unique hydrological and astrobiological implications of the chlorides with polygonal features make these deposits of high priority for future landed on and/or sample return exploration missions of Mars.展开更多
Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performan...Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.展开更多
基金supported by the Open Funds for Hubei Key Laboratory of Marine Geological Resources,China University of Geosciences(No.MGR202303)the National Natural Science Foundation of China(No.41672110)。
文摘The Songliao Basin in northeast China is one of the largest petroliferous basins worldwide,and features the T_(2)fault system,which consists of numerous minor extensional normal faults.This study combines high-resolution 3D seismic datasets to detail the characteristics of the T_(2)fault system,contributing two key findings:(1)The T_(2)faults are confirmed as polygonal fault systems,characterized by closely spaced,layer-bounded faults with small throws,high dip angles,and random orientations,forming intricate polygonal networks.(2)The study reveals the influence of tectonic stresses on the fault system,showing spatial variations across different tectonic units.In depressions,T_(2)faults exhibit short lengths,small throws,high density,and multiple directions.In contrast,in inverted anticline belts,they have longer lengths,bigger throws,higher density,and concordant orientations.These variations demonstrate the impact of tectonic inversion on the development of T_(2)faults.The significance of this research lies in presenting a typical polygonal fault system developed in a deep lake succession and was superposed the influence by regional tectonic stress coeval with its development.The new insights facilitate a reevaluation of the T_(2)fault system's role in hydrocarbon migration and accumulation within the Songliao Basin.
基金financially supported by the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(Grant No.24qnpy041)the Science and Technology Innovation Key R&D Program of Chongqing(Grant No.CSTB2023TIAD-STX0030)。
文摘The electric vertical takeoff and landing(e VTOL)aircraft shows great potential for rapid military personnel deployment on the battlefield.However,its susceptibility to control loss,complex crashes,and extremely limited bottom energy-absorbing space demands higher comprehensive crashworthiness of its subfloor thin-walled structures.This study investigated the energy absorption capacity of novel concave polygonal carbon fiber reinforced plastics(CFRP)tubes under multi-angle collisions.Quasistatic compression experiments and finite element simulations were conducted to assess the failure mode and energy absorption.The influences of cross-section shapes,loading conditions,and geometry parameters on crashworthiness metrics were further analyzed.The results revealed that,under the similar weight,concave polygonal tubes exhibited superior energy absorption under axial loads compared to regular polygonal and circular tubes,attributed to the increased number of axial splits.However,both regular and concave polygonal tubes,particularly the latter,demonstrated reduced oblique energy absorption compared to traditional square tubes with the increasing ratio of SEA value decreased from 20%-16%.Notably,this reduction in energy absorption can be compensated for by the implementation of inward and outward crusher plugs,and with them,the concave polygonal tubes demonstrated outstanding overall crashworthiness performance under multiple loading conditions.This concave cross-sectional design methods could serve as a guidance for the development of the eVTOL subfloor.
基金Supported by National Natural Science Foundation of China(Grant Nos.U2268210,52302474,52072249).
文摘Wheel polygonal wear can immensely worsen wheel/rail interactions and vibration performances of the train and track,and ultimately,lead to the shortening of service life of railway components.At present,wheel/rail medium-or high-frequency frictional interactions are perceived as an essential reason of the high-order polygonal wear of railway wheels,which are potentially resulted by the flexible deformations of the train/track system or other external excitations.In this work,the effect of wheel/rail flexibility on polygonal wear evolution of heavy-haul locomotive wheels is explored with aid of the long-term wheel polygonal wear evolution simulations,in which different flexible modeling of the heavy-haul wheel/rail coupled system is implemented.Further,the mitigation measures for the polygonal wear of heavy-haul locomotive wheels are discussed.The results point out that the evolution of polygonal wear of heavy-haul locomotive wheels can be veritably simulated with consideration of the flexible effect of both wheelset and rails.Execution of mixed-line operation of heavy-haul trains and application of multicut wheel re-profiling can effectively reduce the development of wheel polygonal wear.This research can provide a deep-going understanding of polygonal wear evolution mechanism of heavy-haul locomotive wheels and its mitigation measures.
基金Project supported by the National Natural Science Foundation of China(Grant No.12301580).
文摘The study on the entanglement polygon inequality of multipartite systems has attracted much attention.However,most of the results are on pure states.Here we consider the property for a class of mixed states,which are the reduced density matrices of generalizedW-class states in multipartite higher dimensional systems.First we show the class of mixed states satisfies the entanglement polygon inequalities in terms of Tsallis-q entanglement,then we propose a class of tighter inequalities for mixed states in terms of Tsallis-q entanglement.At last,we get an inequality for the mixed states,which can be regarded as a relation for bipartite entanglement.
基金supported by the National Natural Science Foundation of China (Grant No. 12302238)the National Key Research and Development Program of China (Grant Nos. 2021YFB3400701, 2022YFB3402904)。
文摘The dynamic load distribution within in-service axlebox bearings of high-speed trains is crucial for the fatigue reliability assessment and forward design of axlebox bearings. This paper presents an in situ measurement of the dynamic load distribution in the four rows of two axlebox bearings on a bogie wheelset of a high-speed train under polygonal wheel–rail excitation. The measurement employed an improved strain-based method to measure the dynamic radial load distribution of roller bearings. The four rows of two axlebox bearings on a wheelset exhibited different ranges of loaded zones and different means of distributed loads. Besides, the mean value and standard deviation of measured roller–raceway contact loads showed non-monotonic variations with the frequency of wheel–rail excitation. The fatigue life of the four bearing rows under polygonal wheel–rail excitation was quantitatively predicted by compiling the measured roller–raceway contact load spectra of the most loaded position and considering the load spectra as input.
基金the Sichuan Science and Technology Program of China(No.2024NSFSC0160).
文摘Purpose–This study aims to investigate the cause of high-order wheel polygonization in a plateau high-speed electric multiple unit(EMU)train.Design/methodology/approach–A series of field tests were conducted to measure the vibration accelerations of the axle box and bogie when the wheels of the EMU train passed through tracks with normal rail roughness after re-profiling.Additionally,the dynamic characteristics of the track,wheelset and bogie were also measured.These measurements provided insights into the mechanisms that lead to wheel polygonization.Findings–The results of the field tests indicate that wheel polygonal wear in theEMUtrain primarily exhibits 14–16 and 25–27 harmonic orders.The passing frequencies of wheel polygonization were approximately 283–323 Hz and 505–545 Hz,which closely match the dominated frequencies of axle box and bogie vibrations.These findings suggest that the fixed-frequency vibrations originate from the natural modes of the wheelset and bogie,which can be excited by wheel/rail irregularities.Originality/value–The study provides novel insights into the mechanisms of high-order wheel polygonization in plateau high-speed EMU trains.Futher,the results indicate that operating the EMU train on mixed lines at variable speeds could potentially mitigate high-order polygonal wear,providing practical value for improving the safety,performance and maintenance efficiency of high-speed EMU trains.
文摘An algorithm for partitioning arbitrary simple polygons into a number of convex parts was presented. The concave vertices were determined first, and then they were moved by using the method connecting the concave vertices with the vertices of falling into its region B,so that the primary polygon could be partitioned into two subpolygons. Finally, this method was applied recursively to the subpolygons until all the concave vertices were removed. This algorithm partitions the polygon into O(l) convex parts, its time complexity is max(O(n),O(l 2)) multiplications, where n is the number of vertices of the polygon and l is the number of the concave vertices.
基金the National Natural Science Foundation of China(10172003 and 10372003)
文摘When studying the regular polygonal inclusion in 1997, Nozaki and Taya discovered numerically some remarkable properties of Eshelby tensor： Eshelby tensor at the center and the averaged Eshelby tensor over the inclusion domain are equal to that of a circular inclusion and independent of the orientation of the inclusion. Then Kawashita and Nozaki justified the properties mathematically. In the present paper, some other properties of a regular polygonal inclusion are discovered. We find that for an N-fold regular polygonal inclusion except for a square, the arithmetic mean of Eshelby tensors at N rotational symmetrical points in the inclusion is also equal to the Eshelby tensor for a circular inclusion and independent of the orientation of the inclusion. Furthermore, in two corollaries, we point out that Eshelby tensor at the center, the averaged Eshelby tensor over the inclusion domain, and the line integral average of Eshelby tensors along any concentric circle of the inclusion are all identical with the arithmetic mean.
文摘The formed principle and CNC grinding machining method of isometric polygonal profile are studied deeply and systematically. Equation about section curve of isometric polygon profile is set up by means of geometric principle. With the use of differential geometry theory, the curve is proved to be with geometric feature of convex curve. It is referred to as Isometric Polygonal Curve (IPC), because that is a kind of convex curve on which the distance between any parallel tangent lines is equal. Isometric Polygonal Profile (IPP) or Isometric Polygonal Cone Profile (IPCP) or Isometric Polygonal Topless Cone (IPTC) is formed with the IPC and straight line as generating curve. But the machining and measuring of the IPCP are so inconvenient that it has little value. Keeping in mind the characteristic of the IPP and IPTC, this paper puts forward the program method of CNC grinding machining. Isometric polygonal profile connection is a kind of polygonal profile connection. It has the superiority over keys (prismatic key & spline etc), and can be suit for the situations such as high rotative velocity, large torque, high precision, and small fixed room and vibration. Nowadays, some countries such as America, Russia, German and Switzerland applied CNC machining to the machining of polygon surface coupling parts, which makes their applications in machine productions such as motor engine, heavy machine increase day by day. But reports about concrete machining technology of isometric polygonal profile and programming of CNC machining program are very few. CNC grinding of the IPP and IPTC is one kind of the precision machining technology. It is of great importance to the popularization of the IPP and IPTC connection. From the forming mechanism, we can see that the machining and measuring of the IPP and IPTC are convenient, and therefore they have the value of the popularization. But the machining and measuring of the IPCP are so inconvenient that it has little value. In the programming the CNC grinding of the IPP and IPTC, it is more reasonable to calculate the coordinate of node according to the approaching method of equal error arc. According to the method of CNC grinding mentioned above to design the grinding machine, the structure is simple and of economical and practical.
文摘A new method for point-polygon classification is presented in the paper. The basic idea of the method is first advanced and then two properties of polygon are introduced. The criterions for point-polygon classification are given explicitly. The analysis shows that the possesses perfect function, extensive suitability and high efficiency.
基金Project supported by the National Natural Science Foundation of China （No. U 1134202）
文摘This paper presents a detailed investigation, via field experiment, into the mechanism of high-order polygonal wear of wheels of a new type of high-speed train. The investigation was carried out during the performance acceptance test of the train and its initial commercial operation. The investigation covered the performance acceptance test of 150 000 km and the commercial operation of about 150 000 km. In the performance acceptance test of the first stage of about 70 000 km, at 200-250 km/h with full loading and sometimes overloading by 30%, the serious polygonal wear of 23-order took place on all the wheels of the train, and was measured and analyzed in detail. All the potygonized wheels were re-profiled because the polygonal wear had caused strong vibration and damage to the train parts. After re-profiling, the vibration of the train and track and the wear status of the wheels were measured and analyzed at different test mileages according to the polygonal wear situation of the wheels. The measured vibration of the train includes the accelerations at different positions of a motor car and a trail car. The vibration modes of the key parts of the bogies of the two cars were calculated. Meanwhile, the track resonant frequencies were investigated at the site. The purpose of the above tests and analysis is try to find the frequency of work mode matching the passing frequency of the high-order wheel polygon. The present investigation shows that one of the working models causes the formation and development of the high-order wheel polygonal wear. The growth of this wear was effectively reduced through the frequent changing of the running speed of the train operating on the way back and forth every day.
基金supported by the Formation Mechanism and Study on Geophysical Recognition Technology of Shallow Water Flow (No. 2006AA09Z349)the CAS Knowledge Inno-vation Program (No. KZCX2-YW-203), the National Basic Research Program of China (No. 2007CB411703)+1 种基金the MLR National Petroleum Resource Strategic Target Survey and Evaluation Programthe Taishan Scholarship Program of Shandong Province.
文摘Based on high-resolution 3D seismic data, we document the polygonal faults within the Miocene Meishan （梅山） Formation and Huangliu （黄流） Formation of the Qiongdongnan （琼东南） basin, northern South China Sea. Within the seismic section and time coherent slice, densely distributed extensional faults with small throw and polygonal shape were identified in map view. The orientation of the polygonal faults is almost isotropic, indicating a non-tectonic origin. The deformation is clearly layer-bounded, with horizontal extension of 11.2% to 16%, and 13.2% on average. The distribution of polygonal faults shows a negative correlation with that of gas chimneys. The development of polygonal faults may be triggered by over-pressure pore fluid which is restricted in the fine-grained sediments of bathyal facies when the sediments is compacted by the burden above. The polygonal faults developed to balance the volumetric contraction and restricted extension. The product of hydrocarbon in the Meishan Formation may have contributed to the development of the polygonal faults. In the study area, it was thought that the petroleum system of the Neogene post-rift sequence is disadvantageous because of poor migration pathway. However, the discovery of polygonal faults in the Miocene strata, which may play an important role on the fluid migration, may change this view. A new model of the petroleum system for the study area is proposed.
文摘Voronoi diagram is founded by using computational geometry based on originaldistribution of the waypoints, and then the elements from Voronoi diagram are metamorphosed by usingthe rule for airsppce partition, and the controller's workload is accounted in each element that ismade up of Metamorphic Voronoi polygon. Then in accordance with the rule about balance ofcontroller's workload, Simulated Annealing algorithm (SA) is used to achieve the optimization ofcombination of those elements , and the new resolution has satisfied the restriction of two rulesfor airspace partition. Therefore, the boundaries of the aggregates of these elements are theoptimal borderlines of sectors. The result of actual airspace design example validates therationality of the sector optimization method presented in this paper.
文摘Based on the deformation characteristic of regular polygonal box stamped parts and the superfluous triangle material wrinkle model,the criterion of regular polygonal box stamped parts without wrinkle was deduced and used to predict and control the wrinkle limit.According to the fracture model,the criterion of regular polygonal box stamped parts without fracture was deduced and used to predict and control the fracture limit.Combining the criterion for stamping without wrinkle with that without fracture,the stamping criterion of regular polygonal box stamped parts was obtained to predict and control the stamping limit.Taken the stainless steel0Cr18Ni9(SUS304)sheet and the square box stamped part as examples,the limit diagram was given to predict and control the wrinkle,fracture and stamping limits.It is suitable for the deep drawing without flange,the deep drawing and stretching combined forming with flange and the rigid punch stretching of plane blank.The limit deep-drawing coefficient and the minimum deep-drawing coefficient can be determined,and the appropriate BHF(blank holder force)and the deep-drawing force can be chosen.These provide a reference for the technology planning,the die and mold design and the equipment determination,and a new criterion evaluating sheet stamping formability,which predicts and controls the stamping process,can be applied to the deep drawing under constant or variable BHF conditions.
基金supported by the National Natural Science Foundation of China (41431177 and 41422109)the Innovation Project of State Key Laboratory of Resources and Environmental Information System of China (O88RA20CYA)the Outstanding Innovation Team in Colleges and Universities in Jiangsu Province, China
文摘Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take all polygons of the same map unit on a map as a whole to extract the soil–environment relationship.Such approach ignores the difference in the environmental conditions represented by individual soil polygons of the same map unit.This paper proposes a method of mining soil–environment relationships from individual soil polygons to update conventional soil maps.The proposed method consists of three major steps.Firstly,the soil–environment relationships represented by each individual polygon on a conventional soil map are extracted in the form of frequency distribution curves for the involved environmental covariates.Secondly,for each environmental covariate,these frequency distribution curves from individual polygons of the same soil map unit are synthesized to form the overall soil–environment relationship for that soil map unit across the mapped area.And lastly,the extracted soil–environment relationships are applied to updating the conventional soil map with new,improved environmental data by adopting a soil land inference model(SoLIM)framework.This study applied the proposed method to updating a conventional soil map of the Raffelson watershed in La Crosse County,Wisconsin,United States.The result from the proposed method was compared with that from the previous method of taking all polygons within the same soil map unit on a map as a whole.Evaluation results with independent soil samples showed that the proposed method exhibited better performance and produced higher accuracy.
基金supported by the National Scientific Foundation of China(Nos.41403052,41773061,41830214)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Nos.CUGL160402,CUG2017G02)+1 种基金the Lunar and Planetary Science Laboratory,Macao University of Science and Technology Partner Laboratory of Key Laboratory of Lunar and Deep Space Exploration,Chinese Academy of Sciences(Nos.039/2013/A2,121/2017/A3)supported by the National Training Program of Innovation and Entrepreneurship for Undergraduates(No.201610491122)
文摘Over 600 chloride-bearing deposits(chlorides) have been identified on the southern highlands of Mars. These chlorides have critical implications for hydrology and astrobiology: they are indicators of an evaporating super saturated solution, and they could have provided habitat environments for halophilic microorganisms and preserved organic matter. One of the prominent geomorphology characteristics of these chloridebearing regions is the polygonal features within them. The origin of these polygonal features is still in debate. In this study, we have surveyed 153 locations of chlorides using 441 high resolution imaging science experiment(Hi RISE) images to characterize the geomorphology of polygonal features. We identified 3 types of polygonal features of distinct geomorphologic characteristics: fractures, raised ridges, and transitional polygons between fractures and raised ridges. We evaluate previously proposed hypotheses of the formation of the polygonal features, and suggest that the 3 types of polygonal features are indicators of different stages of salt crust formation. Salt crust is usually formed through multiple groundwater activities, and it often occurs in playa environment on Earth. The unique hydrological and astrobiological implications of the chlorides with polygonal features make these deposits of high priority for future landed on and/or sample return exploration missions of Mars.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675484,51275474,51505424)Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LZ12E05002,LY15E050019)
文摘Load behavior is one of the most critical factors affecting mills＇ energy consumption and grinding efficiency, and is greatly affected by the liner profiles. Generally, as liner profiles vary, the ball mill performances are extremely different. In order to study the performance of the ball mill with regular polygon angle-spiral liners（RPASLs）, experimental and numerical studies on three types of RPASLs, including regular quadrilateral, pentagonal and hexagonal, are carried out. For the fine product of desired size, two critical parameters are analyzed： the energy input to the mill per unit mass of the fine product, E＊, and the rate of production of the fine product, F＊. Results show that the optimal structure of RPASLs is Quadrilateral ASL with an assembled angle of 50°. Under this condition, the specific energy consumption E＊ has the minimum value of 303 J per fine product and the production rate F＊ has the maximum value of 0.323. The production rate F＊ in the experimental result is consistent with the specific collision energy intensity to total collision energy intensity ratio Es/Et in the simulation. The relations between the production rate F＊ and the specific energy consumption E＊ with collision energy intensity Es and Et are obtained. The simulation result reveals the essential reason for the experimental phenomenon and correlates the mill performance parameter to the collision energy between balls, which could guide the practical application for Quadrilateral ASL.
