Increasing velocity combined with decreasing mass of modern highspeed trains poses a question about the influence of strong crosswinds on its aerodynamics. Strong crosswinds may affect the running stability of high sp...Increasing velocity combined with decreasing mass of modern highspeed trains poses a question about the influence of strong crosswinds on its aerodynamics. Strong crosswinds may affect the running stability of high speed trains via the amplified aerodynamic forces and moments. In this study, a simulation of turbulent crosswind flows over the leading and end cars of ICE2 highspeed train was performed at different yaw angles in static and moving ground case scenarios. Since the train aerodynamic problems are closely associated with the flows occurring around train, the flow around the train was considered as incompressible and was obtained by solving the incom pressible form of the unsteady Reynoldsaveraged Navier Stokes (RANS) equations combined with the realizable kepsilon turbulence model. Important aerodynamic coef ficients such as the side force and rolling moment coeffi cients were calculated for yaw angles ranging from 30° to 60° and compared with the results obtained from wind tunnel test. The dependence of the flow structure on yaw angle was also presented. The nature of the flow field and its structure depicted by contours of velocity magnitude and streamline patterns along the train's crosssection were presented for different yaw angles. In addition, the pressure coefficient around the circumference of the train at dif ferent locations along its length was computed for yaw angles of 30° and 60°, The computed aerodynamic coef ficient outcomes using the realizable kepsilon turbulencemodel were in good agreement with the wind tunnel data. Both the side force coefficient and rolling moment coeffi cients increase steadily with yaw angle till about 50° before starting to exhibit an asymptotic behavior. Contours of velocity magnitude were also computed at different cross sections of the train along its length for different yaw angles. The result showed that magnitude of rotating vortex in the lee ward side increased with increasing yaw angle, which leads to the creation of a lowpressure region in the lee ward side of the train causing high side force and roll moment. Generally, this study shows that unsteady CFD RANS methods combined with an appropriate turbulence model can present an important means of assessing the crucial aerodynamic forces and moments of a highspeed train under strong crosswind conditions.展开更多
A single-Rh-site catalyst(Rh-TPISP)that was ionically-embedded on a P(V)quaternary phosphonium porous polymer was evaluated for heterogeneous ethanol carbonylation.The[Rh(CO)I_(3)]^(2-)unit was proposed to be the acti...A single-Rh-site catalyst(Rh-TPISP)that was ionically-embedded on a P(V)quaternary phosphonium porous polymer was evaluated for heterogeneous ethanol carbonylation.The[Rh(CO)I_(3)]^(2-)unit was proposed to be the active center of Rh-TPISP for the carbonylation reaction based on detailed Rh L3-edge X-ray absorption near edge structure(XANES),X-ray photoelectron spectroscopy(XPS),and Rh extended X-ray absorption fine structure(EXAFS)analyses.As the highlight of this study,Rh-TPISP displayed distinctly higher activity for heterogeneous ethanol carbonylation than the reported catalytic systems in which[Rh(CO)_(2)I_(2)]^(-)is the traditional active center.A TOF of 350 h^(-1)was obtained for the reaction over[Rh(CO)I_(3)]^(2-),with>95%propionyl selectivity at 3.5 MPa and 468 K.No deactivation was detected during a near 1000 h running test.The more electron-rich Rh center was thought to be crucial for explaining the superior activity and selectivity of Rh-TPISP,and the formation of two ionic bonds between[Rh(CO)I_(3)]^(2-)and the cationic P(V)framework([P]^(+))of the polymer was suggested to play a key role in firmly immobilizing the active species to prevent Rh leaching.展开更多
In this paper,we prove that a proper μ holomorphic mapping f:D 1→D 2 between bounded domains with some convexity,such that f satisfies some growth condition,extends smoothly to bD 1-{z:U(z)=0}.
This scientific paper is a comparative analysis of two mathematical conjectures. The newly proposed -3(-n) - 1 Remer conjecture and how it is related to and a proof of the more well known 3n + 1 Collatz conjecture. An...This scientific paper is a comparative analysis of two mathematical conjectures. The newly proposed -3(-n) - 1 Remer conjecture and how it is related to and a proof of the more well known 3n + 1 Collatz conjecture. An overview of both conjectures and their respective iterative processes will be presented. Showcasing their unique properties and behavior to each other. Through a detailed comparison, we highlight the similarities and differences between these two conjectures and discuss their significance in the field of mathematics. And how they prove each other to be true.展开更多
Whole trip longitudinal dynamics and energy analysis of heavy haul trains are required by operators and manufacturers to enable optimisation of train controls and rolling stock components. A new technology named train...Whole trip longitudinal dynamics and energy analysis of heavy haul trains are required by operators and manufacturers to enable optimisation of train controls and rolling stock components. A new technology named train dynamics and energy analyser/train simulator (TDEAS) has been developed by the State Key Laboratory of Traction Power in China to perform detailed whole trip longitudinal train dynamics and energy analyses. Facilitated by a controller user interface and a graphic user interface, the TDEAS can also be used as a train driving simulator. This paper elaborates the modelling of three primary parts in the TDEAS, namely wagon connection systems, air brake systems and train energy components. TDEAS uses advanced wedge-spring draft gear models that can simulate a wider spectrum of friction draft gear behaviour. An effective and efficient air brake model that can simulate air brake systems in various train configurations has been integrated. In addition, TDEAS simulates the train energy on the basis of a detailed longitudinal train dynamics simulation, which enables a further perspective of the train energy composition and the overall energy consumption. To demonstrate the validity of the TDEAS, a case study was carried out on a 120-km-long Chinese railway. The results show that the employment of electric locomotives with regenerative braking could bring considerable energy benefits. Nearly 40 % of the locomotive energy usage could be collected from the dynamic brake system. Most of tractive energy was dissipated by propulsion resistance that accounted for 42.48 % of the total energy. Only a small amount of tractive energy was dissipated by curving resistance, air brake and draft gear systems.展开更多
This paper presents the formulation and solution of a train routing and makeupmodel.This formulation results in a large scale 0-1 integer programmingproblem with nonlinear objective function, and linear and nonlinearc...This paper presents the formulation and solution of a train routing and makeupmodel.This formulation results in a large scale 0-1 integer programmingproblem with nonlinear objective function, and linear and nonlinearcoastraints. We know this problem is NP-complete;hence,it is diffieult to solvefor a globelly optimal solution. In this paper we propose a simulated annealingalgorithm for the train routing and makeup problem. This method avoidsentrapment in the local minima of the objective function. The effectiveness ofthis approach has been demonstrasted by results from test casee,展开更多
The authoros specialize in the field of optunization and automatic programme oftrain working graph. In this peper, at frist, a mixed 0-1 integer progranimingmodel about this problem for duuble-track lines is set up, t...The authoros specialize in the field of optunization and automatic programme oftrain working graph. In this peper, at frist, a mixed 0-1 integer progranimingmodel about this problem for duuble-track lines is set up, then the principle andProcess of selution are stated, with an application exaiiiple put forward.展开更多
The CD retrieval svstem of Journal of Traditional Chinese Medicine(JTCM)contains all of the periodicals of JTCM published from 1981 to 2008.You can read any articles on computer bv searching any words or combination o...The CD retrieval svstem of Journal of Traditional Chinese Medicine(JTCM)contains all of the periodicals of JTCM published from 1981 to 2008.You can read any articles on computer bv searching any words or combination of the words.The retrieval results can be printed or downloaded.You may retrieve the relevant articles about a certain disease,therapy or drug in a few seconds,user-friendly with convenient handling.展开更多
The CD retrieval system of Journal of Traditional Chinese Medicine (JTCM) contains all of the periodicals of JTCM published from 1981 to 2008. You can read any articles on computer by searching any words or combinatio...The CD retrieval system of Journal of Traditional Chinese Medicine (JTCM) contains all of the periodicals of JTCM published from 1981 to 2008. You can read any articles on computer by searching any words or combination of the words.The retrieval results can be printed or downloaded. You may retrieve the relevant articles about a certain disease.展开更多
A good contact between the pantograph and catenary is critically important for the working reliability of electric trains, while the basic understanding on the electrical contact evolution during the pantograph--caten...A good contact between the pantograph and catenary is critically important for the working reliability of electric trains, while the basic understanding on the electrical contact evolution during the pantograph--catenary system working is still ambiguous so far. In this paper, the evolution of electric contact was studied in respects of the contact resistance, temperature rise, and microstructure variation, based on a home-made pantograph-catenary simulation system. Pure carbon strips and copper alloy contact wires were used, and the experimental electrical current, sliding speed, and normal force were set as 80 A, 30 km/h, and 80 N, respectively. The contact resistance presented a fluctuation without obvious regularity, concentrating in the region of 25 and 50 mf~. Temperature rise of the contact point experienced a fast increase at the first several minutes and finally reached a steady state. The surface damage of carbon trips in microstructure analysis revealed a complicated interaction of the sliding friction, joule heating, and arc erosion.展开更多
A three-dimensional (3-D) wheel-rail rolling contact model with a wheel fiat was built using commercial software Hypermesh, and the dynamic finite element simulation was conducted using LS-DYNA 3D/explicit code. Inf...A three-dimensional (3-D) wheel-rail rolling contact model with a wheel fiat was built using commercial software Hypermesh, and the dynamic finite element simulation was conducted using LS-DYNA 3D/explicit code. Influences of the train speed, flat length and axle load on the vertical wheel-rail impact response were discussed, respectively. The results show that the maximum vertical wheel-rail impact force induced by the wheel flat is higher than that generated by the perfect wheel, and these two dynamic impact forces are much greater than the static axle load. Besides, the maximum von Mises equivalent stress and maximum equivalent plastic strain are observed on the wheel-rail contact surface, and both of them as well as the maximum wheel-rail impact force are sensitive to train speed, fiat length and axle load.展开更多
With the increasing of complexity of complex mechatronic products, it is necessary to involve multidis- ciplinary design teams, thus, the traditional customer requirements modeling for a single discipline team becomes...With the increasing of complexity of complex mechatronic products, it is necessary to involve multidis- ciplinary design teams, thus, the traditional customer requirements modeling for a single discipline team becomes difficult to be applied in a multidisciplinary team and project since team members with various disciplinary backgrounds may have different interpretations of the customers' requirements. A new synthesized multidisci- plinary customer requirements modeling method is pro- vided for obtaining and describing the common understanding of customer requirements (CRs) and more importantly transferring them into a detailed and accurate product design specifications (PDS) to interact with dif- ferent team members effectively. A case study of designing a high speed train verifies the rationality and feasibility of the proposed multidisciplinary requirement modeling method for complex mechatronic product development. This proposed research offersthe instruction to realize the customer-driven personalized customization of complex mechatronic product.展开更多
Y2001-62851-631 02014232阶∑△模-数转换器的自适应积分器输出边界=Adaptive integrator-output bounding for second order Sig-ma-Delta ADC[会,英]/Sun,X.-H.& Laker,K.R.//2000 5<sup>th</sup> International Con...Y2001-62851-631 02014232阶∑△模-数转换器的自适应积分器输出边界=Adaptive integrator-output bounding for second order Sig-ma-Delta ADC[会,英]/Sun,X.-H.& Laker,K.R.//2000 5<sup>th</sup> International Conference on Signal Process-ing Proceedings,Vol.Ⅰ of Ⅲ.—631~634(HC)Y2001-62877-336 0201424信噪比为95dB 采样速率2.5M/秒多位△∑ CMOS 模/数转换器=A2.5M Sample/S multi-bit △∑ CMOS ADCwith 95dB SNR[会,英]/Geerts,Y.& Steyaert,M.//2000 IEEE International Solid-State Circuits Conference,Digest.—336~337(EC)展开更多
文摘Increasing velocity combined with decreasing mass of modern highspeed trains poses a question about the influence of strong crosswinds on its aerodynamics. Strong crosswinds may affect the running stability of high speed trains via the amplified aerodynamic forces and moments. In this study, a simulation of turbulent crosswind flows over the leading and end cars of ICE2 highspeed train was performed at different yaw angles in static and moving ground case scenarios. Since the train aerodynamic problems are closely associated with the flows occurring around train, the flow around the train was considered as incompressible and was obtained by solving the incom pressible form of the unsteady Reynoldsaveraged Navier Stokes (RANS) equations combined with the realizable kepsilon turbulence model. Important aerodynamic coef ficients such as the side force and rolling moment coeffi cients were calculated for yaw angles ranging from 30° to 60° and compared with the results obtained from wind tunnel test. The dependence of the flow structure on yaw angle was also presented. The nature of the flow field and its structure depicted by contours of velocity magnitude and streamline patterns along the train's crosssection were presented for different yaw angles. In addition, the pressure coefficient around the circumference of the train at dif ferent locations along its length was computed for yaw angles of 30° and 60°, The computed aerodynamic coef ficient outcomes using the realizable kepsilon turbulencemodel were in good agreement with the wind tunnel data. Both the side force coefficient and rolling moment coeffi cients increase steadily with yaw angle till about 50° before starting to exhibit an asymptotic behavior. Contours of velocity magnitude were also computed at different cross sections of the train along its length for different yaw angles. The result showed that magnitude of rotating vortex in the lee ward side increased with increasing yaw angle, which leads to the creation of a lowpressure region in the lee ward side of the train causing high side force and roll moment. Generally, this study shows that unsteady CFD RANS methods combined with an appropriate turbulence model can present an important means of assessing the crucial aerodynamic forces and moments of a highspeed train under strong crosswind conditions.
文摘A single-Rh-site catalyst(Rh-TPISP)that was ionically-embedded on a P(V)quaternary phosphonium porous polymer was evaluated for heterogeneous ethanol carbonylation.The[Rh(CO)I_(3)]^(2-)unit was proposed to be the active center of Rh-TPISP for the carbonylation reaction based on detailed Rh L3-edge X-ray absorption near edge structure(XANES),X-ray photoelectron spectroscopy(XPS),and Rh extended X-ray absorption fine structure(EXAFS)analyses.As the highlight of this study,Rh-TPISP displayed distinctly higher activity for heterogeneous ethanol carbonylation than the reported catalytic systems in which[Rh(CO)_(2)I_(2)]^(-)is the traditional active center.A TOF of 350 h^(-1)was obtained for the reaction over[Rh(CO)I_(3)]^(2-),with>95%propionyl selectivity at 3.5 MPa and 468 K.No deactivation was detected during a near 1000 h running test.The more electron-rich Rh center was thought to be crucial for explaining the superior activity and selectivity of Rh-TPISP,and the formation of two ionic bonds between[Rh(CO)I_(3)]^(2-)and the cationic P(V)framework([P]^(+))of the polymer was suggested to play a key role in firmly immobilizing the active species to prevent Rh leaching.
文摘In this paper,we prove that a proper μ holomorphic mapping f:D 1→D 2 between bounded domains with some convexity,such that f satisfies some growth condition,extends smoothly to bD 1-{z:U(z)=0}.
文摘This scientific paper is a comparative analysis of two mathematical conjectures. The newly proposed -3(-n) - 1 Remer conjecture and how it is related to and a proof of the more well known 3n + 1 Collatz conjecture. An overview of both conjectures and their respective iterative processes will be presented. Showcasing their unique properties and behavior to each other. Through a detailed comparison, we highlight the similarities and differences between these two conjectures and discuss their significance in the field of mathematics. And how they prove each other to be true.
文摘Whole trip longitudinal dynamics and energy analysis of heavy haul trains are required by operators and manufacturers to enable optimisation of train controls and rolling stock components. A new technology named train dynamics and energy analyser/train simulator (TDEAS) has been developed by the State Key Laboratory of Traction Power in China to perform detailed whole trip longitudinal train dynamics and energy analyses. Facilitated by a controller user interface and a graphic user interface, the TDEAS can also be used as a train driving simulator. This paper elaborates the modelling of three primary parts in the TDEAS, namely wagon connection systems, air brake systems and train energy components. TDEAS uses advanced wedge-spring draft gear models that can simulate a wider spectrum of friction draft gear behaviour. An effective and efficient air brake model that can simulate air brake systems in various train configurations has been integrated. In addition, TDEAS simulates the train energy on the basis of a detailed longitudinal train dynamics simulation, which enables a further perspective of the train energy composition and the overall energy consumption. To demonstrate the validity of the TDEAS, a case study was carried out on a 120-km-long Chinese railway. The results show that the employment of electric locomotives with regenerative braking could bring considerable energy benefits. Nearly 40 % of the locomotive energy usage could be collected from the dynamic brake system. Most of tractive energy was dissipated by propulsion resistance that accounted for 42.48 % of the total energy. Only a small amount of tractive energy was dissipated by curving resistance, air brake and draft gear systems.
文摘This paper presents the formulation and solution of a train routing and makeupmodel.This formulation results in a large scale 0-1 integer programmingproblem with nonlinear objective function, and linear and nonlinearcoastraints. We know this problem is NP-complete;hence,it is diffieult to solvefor a globelly optimal solution. In this paper we propose a simulated annealingalgorithm for the train routing and makeup problem. This method avoidsentrapment in the local minima of the objective function. The effectiveness ofthis approach has been demonstrasted by results from test casee,
文摘The authoros specialize in the field of optunization and automatic programme oftrain working graph. In this peper, at frist, a mixed 0-1 integer progranimingmodel about this problem for duuble-track lines is set up, then the principle andProcess of selution are stated, with an application exaiiiple put forward.
文摘The CD retrieval svstem of Journal of Traditional Chinese Medicine(JTCM)contains all of the periodicals of JTCM published from 1981 to 2008.You can read any articles on computer bv searching any words or combination of the words.The retrieval results can be printed or downloaded.You may retrieve the relevant articles about a certain disease,therapy or drug in a few seconds,user-friendly with convenient handling.
文摘The CD retrieval system of Journal of Traditional Chinese Medicine (JTCM) contains all of the periodicals of JTCM published from 1981 to 2008. You can read any articles on computer by searching any words or combination of the words.The retrieval results can be printed or downloaded. You may retrieve the relevant articles about a certain disease.
基金supported by the National Natural Science Foundation of China (Nos. U1234202 and 51577158)the National Science Foundation for Distinguished Young Scholars of China (No. 51325704)the Fundamental Research Funds for the Central Universities (No. A0920502051505-19)
文摘A good contact between the pantograph and catenary is critically important for the working reliability of electric trains, while the basic understanding on the electrical contact evolution during the pantograph--catenary system working is still ambiguous so far. In this paper, the evolution of electric contact was studied in respects of the contact resistance, temperature rise, and microstructure variation, based on a home-made pantograph-catenary simulation system. Pure carbon strips and copper alloy contact wires were used, and the experimental electrical current, sliding speed, and normal force were set as 80 A, 30 km/h, and 80 N, respectively. The contact resistance presented a fluctuation without obvious regularity, concentrating in the region of 25 and 50 mf~. Temperature rise of the contact point experienced a fast increase at the first several minutes and finally reached a steady state. The surface damage of carbon trips in microstructure analysis revealed a complicated interaction of the sliding friction, joule heating, and arc erosion.
基金supported by the National Natural Science Foundation of China (Grant No. 51475392)the Fundamental Research Funds for the Central Universities (Grant No. 2682015RC09)the Research Fund of State Key Laboratory of Traction Power (Grant No. 2015TPL_T02)
文摘A three-dimensional (3-D) wheel-rail rolling contact model with a wheel fiat was built using commercial software Hypermesh, and the dynamic finite element simulation was conducted using LS-DYNA 3D/explicit code. Influences of the train speed, flat length and axle load on the vertical wheel-rail impact response were discussed, respectively. The results show that the maximum vertical wheel-rail impact force induced by the wheel flat is higher than that generated by the perfect wheel, and these two dynamic impact forces are much greater than the static axle load. Besides, the maximum von Mises equivalent stress and maximum equivalent plastic strain are observed on the wheel-rail contact surface, and both of them as well as the maximum wheel-rail impact force are sensitive to train speed, fiat length and axle load.
基金Supported by Open Outreach Project of A New Biomimicry and Crowdsourcing Based Digital Design Platform for High Speed Train from State Key Laboratory of Traction PowerNational Natural Science Foundation of China(Grant No.51575461)
文摘With the increasing of complexity of complex mechatronic products, it is necessary to involve multidis- ciplinary design teams, thus, the traditional customer requirements modeling for a single discipline team becomes difficult to be applied in a multidisciplinary team and project since team members with various disciplinary backgrounds may have different interpretations of the customers' requirements. A new synthesized multidisci- plinary customer requirements modeling method is pro- vided for obtaining and describing the common understanding of customer requirements (CRs) and more importantly transferring them into a detailed and accurate product design specifications (PDS) to interact with dif- ferent team members effectively. A case study of designing a high speed train verifies the rationality and feasibility of the proposed multidisciplinary requirement modeling method for complex mechatronic product development. This proposed research offersthe instruction to realize the customer-driven personalized customization of complex mechatronic product.
文摘Y2001-62851-631 02014232阶∑△模-数转换器的自适应积分器输出边界=Adaptive integrator-output bounding for second order Sig-ma-Delta ADC[会,英]/Sun,X.-H.& Laker,K.R.//2000 5<sup>th</sup> International Conference on Signal Process-ing Proceedings,Vol.Ⅰ of Ⅲ.—631~634(HC)Y2001-62877-336 0201424信噪比为95dB 采样速率2.5M/秒多位△∑ CMOS 模/数转换器=A2.5M Sample/S multi-bit △∑ CMOS ADCwith 95dB SNR[会,英]/Geerts,Y.& Steyaert,M.//2000 IEEE International Solid-State Circuits Conference,Digest.—336~337(EC)