Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled t...Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.展开更多
The urban spatial structure reflects a city’s development history,cultural heritage,and socio-economic conditions.A rational urban spatial structure is crucial for urban development.This study focuses on the main urb...The urban spatial structure reflects a city’s development history,cultural heritage,and socio-economic conditions.A rational urban spatial structure is crucial for urban development.This study focuses on the main urban area of Nanjing,analyzing POI and nighttime light data from 2016 to 2020.Utilizing kernel density estimation and coupling coordination models,it explores the temporal and spatial evolution characteristics of Nanjing’s urban spatial structure.Geographic detectors are employed to assess the impact of various factors on this structure.The findings indicate that:(1)Nanjing’s urban spatial structure displays a pattern of central aggregation and peripheral expansion,with high brightness concentrated in the urban center and a significant increase in peripheral brightness,signaling initial success in establishing urban subcenters;(2)The coupling relationship between nighttime light brightness and POI density has strengthened,suggesting improved coordination of the urban spatial structure;(3)The evolution of Nanjing’s urban spatial structure results from the combined effects of multiple factors,including economic level,population distribution,transportation conditions,and policy planning.展开更多
This paper prepared a novel as-cast W-Zr-Ti metallic ESM using high-frequency vacuum induction melting technique.The above ESM performs a typical elastic-brittle material feature and strain rate strengthening behavior...This paper prepared a novel as-cast W-Zr-Ti metallic ESM using high-frequency vacuum induction melting technique.The above ESM performs a typical elastic-brittle material feature and strain rate strengthening behavior.The specimens exhibit violent chemical reaction during the fracture process under the impact loading,and the size distribution of their residual debris follows Rosin-Rammler model.The dynamic fracture toughness is obtained by the fitting of debris length scale,approximately 1.87 MPa·m~(1/2).Microstructure observation on residual debris indicates that the failure process is determined by primary crack propagation under quasi-static compression,while it is affected by multiple cracks propagation in both particle and matrix in the case of dynamic impact.Impact test demonstrates that the novel energetic fragment performs brilliant penetration and combustion effect behind the front target,leading to the effective ignition of fuel tank.For the brittleness of as-cast W-ZrTi ESM,further study conducted bond-based peridynamic(BB-PD)C++computational code to simulate its fracture behavior during penetration.The BB-PD method successfully captured the fracture process and debris cloud formation of the energetic fragment.This paper explores a novel as-cast metallic ESM,and provides an available numerical avenue to the simulation of brittle energetic fragment.展开更多
Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms.Therefore,the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of intere...Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms.Therefore,the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of interest.Based on this purpose,this paper deals with the type synthesis of 1T2R parallel mechanisms by investigating the topological structure coupling-reducing of the 3UPS&UP parallel mechanism.With the aid of the theory of mechanism topology,the analysis of the topological characteristics of the 3UPS&UP parallel mechanism is presented,which shows that there are highly coupled motions and constraints amongst the limbs of the mechanism.Three methods for structure coupling-reducing of the 3UPS&UP parallel mechanism are proposed,resulting in eight new types of 1T2R parallel mechanisms with one or zero coupling degree.One obtained parallel mechanism is taken as an example to demonstrate that a mechanism with zero coupling degree has an explicit form for forward kinematics.The process of type synthesis is in the order of permutation and combination;therefore,there are no omissions.This method is also appli cable to other configurations,and novel topological structures having simple forward kinematics can be obtained from an original mechanism via this method.展开更多
For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo...For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.展开更多
Using a sample of 14 prefecture-level cities in Liaoning Province, this study first explored the spatial hierarchy and structural characteristics of energy efficiency from the following three viewpoints： energy techn...Using a sample of 14 prefecture-level cities in Liaoning Province, this study first explored the spatial hierarchy and structural characteristics of energy efficiency from the following three viewpoints： energy technical efficiency based on data envelopment analysis, energy consumption per unit of GDP, and energy utilization efficiency combining the previous two indexes After measuring and analyzing the advancement, rationality, and concentration of the industrial structure in each city, we made some generalizations about the coupling features of the energy efficiency and industrial structure in Liaoning, using the coupling degree rating model Some of our conclusions are as follows： （1） The 14 cities differ significantly in their en- ergy efficiency, with Shenyang, Dalian, Anshan, and Jinzhou enjoying the highest energy effi- ciency. Northwestern Liaoning and other heavy-industrial cities such as Fushun and Benxi belong to low-efficiency and high-consumption areas. （2） In areas with higher efficiency, the spatial patterns of the energy technical efficiency, energy consumption per unit of GDP, and energy utilization efficiency are, respectively, ＂π ＂-, ＂Ⅱ＂- and ＂H＂- shaped. Geographically, the energy utilization efficiency shows different trends from east to west and from north to south. Factors such as the binuclear structure of economic development have a major effect on this spatial pattern of energy efficiency. （3） Southeastern Liaoning enjoys a highly advanced in- dustrial structure. Areas with a highly rational industrial structure form an ＂H＂ shape, with Shenyang and Dalian at the two poles. The urban agglomerations in middle and southern Liaoning have a highly concentrated industrial structure. （4） Overall, the coupling between energy efficiency and industrial structure is low in Liaoning, except for Shenyang and Dalian at both ends, where the coupling between an advanced industrial structure and energy efficiency is higher than in other cities.展开更多
Based on the results of two dimension velo city structure, 1∶100 000 aeromagnetic anomaly, 1∶200 000 bouguer gravity anom aly and seismic anisotropy of Jiaodong and neighboring region in Shandong, China , the info...Based on the results of two dimension velo city structure, 1∶100 000 aeromagnetic anomaly, 1∶200 000 bouguer gravity anom aly and seismic anisotropy of Jiaodong and neighboring region in Shandong, China , the information of geophysical field was divided into two parts: deep and sh allow focus fields. And then, the information of two different fields was c ombined with that of deep seated geology and ore deposit features. The syntheti c result was adopted to analyze three dimension structure, to probe into crust mantle coupling effects of mineralization and dynamics of ore formation system .展开更多
With the high speed, the rotor of magnetically suspended permanent magnet synchronous motor(MSPMSM) suffers great thermal stress and mechanical stress resulting from the temperature rise problem caused by rotor losses...With the high speed, the rotor of magnetically suspended permanent magnet synchronous motor(MSPMSM) suffers great thermal stress and mechanical stress resulting from the temperature rise problem caused by rotor losses, which leads to instability and inefficiency.In this paper, the mechanical–temperature field coupling analysis is conducted to analyze the relationship between the temperature field and structure, and multi-objective optimization of a rotor is performed to improve the design reliability and efficiency. Firstly, the temperature field is calculated by the 2 D finite element model of MSPMSM and the method of applying the 2 D temperature result to the 3 D finite element model of the motor rotor equivalently is proposed. Then the thermal–structure coupling analysis is processed through mathematic method and finite element method(FEM),in which the 3 D finite element model is established precisely in a way and approaches the practical operation state further. Moreover, the impact produced by the temperature and structure on the mechanical strength is analyzed in detail. Finally, the optimization mathematical model of the motor rotor is established with Sequential Quadratic Programming-NLPQL selected in the optimization scheme. Through optimization, the strength of the components in the motor rotor increases obviously and satisfies the design requirement, which to a great extend enhances the service life of the MSPMSM rotor.展开更多
The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activa...The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activation dynamics in neural networks, and the stability of computing in structural analysis and design were stated briefly. It was successfully applied to nonlinear neural network to evaluate the stability of underground stope structure in a gold mine. With the application of BP network, it is proven that the neuro-com- puting is a practical and advanced tool for solving large-scale underground rock engineering problems.展开更多
The seismic response characteristics of underground structures in saturated soils are investigated.A fully fluid-solid coupling dynamic model is developed and implemented into ABAQUS with a user-defined element to sim...The seismic response characteristics of underground structures in saturated soils are investigated.A fully fluid-solid coupling dynamic model is developed and implemented into ABAQUS with a user-defined element to simulate the dynamic behavior of saturated soils.The accuracy of the model is validated using a classic example in literature.The performance of the model is verified by its application on simulating the seismic response characteristics of a subway station built in saturated soils.The merits of the model are demonstrated by comparing the difference of the seismic response of an underground structure in saturated soils between using the fully coupling model and a single-phase medium model.The study finds that the fully coupling model developed herein can simulate the dynamic response characteristics of the underground structures in saturated soils with high accuracy.The seismic response of the underground structure tends to be underestimated by using the single-phase medium model compared with using the fully coupling model,which provides a weaker confining action to the underground structure.展开更多
By using a Lie algebra, an integrable couplings of the classicai-Boussinesq hierarchy is obtained. Then, the Hamiltonian structure of the integrable couplings of the classical-Boussinesq is obtained by the quadratic-f...By using a Lie algebra, an integrable couplings of the classicai-Boussinesq hierarchy is obtained. Then, the Hamiltonian structure of the integrable couplings of the classical-Boussinesq is obtained by the quadratic-form identity.展开更多
The determination of natural products stereochemistry remains a formidable task.Residual dipolar couplings(RDCs)induced by anisotropic media are a powerful tool for determination of the stereochemistry of organic mole...The determination of natural products stereochemistry remains a formidable task.Residual dipolar couplings(RDCs)induced by anisotropic media are a powerful tool for determination of the stereochemistry of organic molecule in solution.This review will provide a short introduction on RDCs-based methodology for the structural elucidation of natural products.Special attention is given to the current availability of alignment media in organic solvents.The applications of RDCs for structural analysis of some examples of natural products were discussed and summarized.Graphical Abstract This review provides a short introduction on RDCs-based methodology for the structural elucidation of natural products.Special attention is given to the current availability of alignment media in organic solvents.The applications of RDCs for structural analysis of some examples of natural products were discussed and summarized.展开更多
We construct nonlinear super integrable couplings of the super integrable Dirac hierarchy based on an enlarged matrix Lie superalgebra.Then its super Hamiltonian structure is furnished by super trace identity.As its r...We construct nonlinear super integrable couplings of the super integrable Dirac hierarchy based on an enlarged matrix Lie superalgebra.Then its super Hamiltonian structure is furnished by super trace identity.As its reduction,we gain the nonlinear integrable couplings of the classical integrable Dirac hierarchy.展开更多
The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more ...The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.展开更多
Firstly, a vector loop algebra G3 is constructed, by use of it multi-component KN hierarchy is obtained. Further, by taking advantage of the extending vector loop algebras G6 and G9 of G3 the double integrable couplin...Firstly, a vector loop algebra G3 is constructed, by use of it multi-component KN hierarchy is obtained. Further, by taking advantage of the extending vector loop algebras G6 and G9 of G3 the double integrable couplings of the multi-component KN hierarchy are worked out respectively. Finally, Hamiltonian structures of obtained system are given by quadratic-form identity.展开更多
In this paper, a new nonlinear integrable coupling system of the soliton hierarchy is presented. Prom the Lax pairs, the coupled KdV equations are constructed successfully. Based on the prolongation method of Wahlquis...In this paper, a new nonlinear integrable coupling system of the soliton hierarchy is presented. Prom the Lax pairs, the coupled KdV equations are constructed successfully. Based on the prolongation method of Wahlquist and Estabrook, we study the prolongation structure of the nonlinear integrable couplings of the KdV equation.展开更多
In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/re...In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km-deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault reaches the Quaternary stratum, except that the Xinhe fault cuts through the mid-Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the large Xingtai earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other It not only transmits partial energy and deformation between the upper and lower crust,but also has a certain decoupling effect. Finally we conclude that active faults do not necessarily reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also inferred to in this study.展开更多
This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corr...This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench.The flow transport behavior,heat transfer across the hose layers,and structural response caused by the flow are analyzed.Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose.The study found that,compared with a regular operating condition,higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress.The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface,showing little temperature change with respect to material thermal conductivity and ambient temperature.The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.展开更多
Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using angle-resolved photoemission spectroscopy and ab initio calculation, we investigate the electr...Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using angle-resolved photoemission spectroscopy and ab initio calculation, we investigate the electronic structure of Cu_(2)TlX_(2)(X = Se, Te), ternary transition metal chalcogenides with quasi-two-dimensional crystal structure. The band dispersions near the Fermi level are mainly contributed by the Te/Se p orbitals. According to our ab-initio calculation, the electronic structure changes from a semiconductor with indirect band gap in Cu_(2)TlSe_(2) to a semimetal in Cu_(2)TlTe_(2), suggesting a band-gap tunability with the composition of Se and Te. By comparing ARPES experimental data with the calculated results, we identify strong modulation of the band structure by spin–orbit coupling in the compounds. Our results provide a ternary platform to study and engineer the electronic properties of transition metal chalcogenides related to large spin–orbit coupling.展开更多
The effect of temperature and hydrogen addition on undesired carbonaceous deposit formation during methane coupling was studied in DBD-plasma catalytic-wall reactors with Pd/Al2 O3, using electrical power to drive the...The effect of temperature and hydrogen addition on undesired carbonaceous deposit formation during methane coupling was studied in DBD-plasma catalytic-wall reactors with Pd/Al2 O3, using electrical power to drive the reaction.Experiments with thin catalyst layers allowed comparison of the performance of empty reactors and catalytic wall reactors without significantly influencing the plasma properties.The product distribution varies strongly in the temperature window between 25 and 200℃Minimal formation of deposits is found at an optimal temperature around 75℃ in the catalytic-wall reactors.The selectivity to deposits was c.a.10% with only 9 mg of catalyst loading instead of 45% in the blank reactor,while decreasing methane conversion only mildly.Co-feeding H2 to an empty reactor causes a similar decrease in selectivity to deposits,but in this case methane conversion also decreased significantly.Suppression of deposits formation in the catalytic-wall reactor at 75℃ is due to catalytic hydrogenation of mainly acetylene to ethylene.In the empty reactor,H2 co-feed decreases conversion but does not change the product distribution.The catalytic-wall reactors can be regenerated with H2-plasma at room temperature,which produces more added-value hydrocarbons.展开更多
基金supported by the Research Project on Strengthening the Construction of an Important Ecological Security Barrier in Northern China by Higher Education Institutions in the Inner Mongolia Autonomous Region(STAQZX202313)the Inner Mongolia Autonomous Region Education Science‘14th Five-Year Plan’2024 Annual Research Project(NGJGH2024635).
文摘Vacancy defects,as fundamental disruptions in metallic lattices,play an important role in shaping the mechanical and electronic properties of aluminum crystals.However,the influence of vacancy position under coupled thermomechanical fields remains insufficiently understood.In this study,transmission and scanning electron microscopy were employed to observe dislocation structures and grain boundary heterogeneities in processed aluminum alloys,suggesting stress concentrations and microstructural inhomogeneities associated with vacancy accumulation.To complement these observations,first-principles calculations and molecular dynamics simulations were conducted for seven single-vacancy configurations in face-centered cubic aluminum.The stress response,total energy,density of states(DOS),and differential charge density were examined under varying compressive strain(ε=0–0.1)and temperature(0–600 K).The results indicate that face-centered vacancies tend to reduce mechanical strength and perturb electronic states near the Fermi level,whereas corner and edge vacancies appear to have weaker effects.Elevated temperatures may partially restore electronic uniformity through thermal excitation.Overall,these findings suggest that vacancy position exerts a critical but position-dependent influence on coupled structure-property relationships,offering theoretical insights and preliminary experimental support for defect-engineered aluminum alloy design.
基金funded by the 2024 Philosophy and Social Science Research in Colleges and Universities Program in Jiangsu Province(Grant No.2024SJYB0167)the 2023 Nanjing Tech University Talent Introduction and Development Program(Grant No.YPJH2023-03)the research project of Observation Research Station of Land Ecology and Land Use in the Yangtze River Delta,Ministry of Natural Resources(Grant No.2023YRDLELU05).
文摘The urban spatial structure reflects a city’s development history,cultural heritage,and socio-economic conditions.A rational urban spatial structure is crucial for urban development.This study focuses on the main urban area of Nanjing,analyzing POI and nighttime light data from 2016 to 2020.Utilizing kernel density estimation and coupling coordination models,it explores the temporal and spatial evolution characteristics of Nanjing’s urban spatial structure.Geographic detectors are employed to assess the impact of various factors on this structure.The findings indicate that:(1)Nanjing’s urban spatial structure displays a pattern of central aggregation and peripheral expansion,with high brightness concentrated in the urban center and a significant increase in peripheral brightness,signaling initial success in establishing urban subcenters;(2)The coupling relationship between nighttime light brightness and POI density has strengthened,suggesting improved coordination of the urban spatial structure;(3)The evolution of Nanjing’s urban spatial structure results from the combined effects of multiple factors,including economic level,population distribution,transportation conditions,and policy planning.
文摘This paper prepared a novel as-cast W-Zr-Ti metallic ESM using high-frequency vacuum induction melting technique.The above ESM performs a typical elastic-brittle material feature and strain rate strengthening behavior.The specimens exhibit violent chemical reaction during the fracture process under the impact loading,and the size distribution of their residual debris follows Rosin-Rammler model.The dynamic fracture toughness is obtained by the fitting of debris length scale,approximately 1.87 MPa·m~(1/2).Microstructure observation on residual debris indicates that the failure process is determined by primary crack propagation under quasi-static compression,while it is affected by multiple cracks propagation in both particle and matrix in the case of dynamic impact.Impact test demonstrates that the novel energetic fragment performs brilliant penetration and combustion effect behind the front target,leading to the effective ignition of fuel tank.For the brittleness of as-cast W-ZrTi ESM,further study conducted bond-based peridynamic(BB-PD)C++computational code to simulate its fracture behavior during penetration.The BB-PD method successfully captured the fracture process and debris cloud formation of the energetic fragment.This paper explores a novel as-cast metallic ESM,and provides an available numerical avenue to the simulation of brittle energetic fragment.
基金Supported by National Key R&D program of China(Grant No.2017YFB1301800)National Natural Science Foundation of China(Grant No.51622508)National Defense Basic Scientific Research program of China(Grant No.JCKY2017203B066)
文摘Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms.Therefore,the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of interest.Based on this purpose,this paper deals with the type synthesis of 1T2R parallel mechanisms by investigating the topological structure coupling-reducing of the 3UPS&UP parallel mechanism.With the aid of the theory of mechanism topology,the analysis of the topological characteristics of the 3UPS&UP parallel mechanism is presented,which shows that there are highly coupled motions and constraints amongst the limbs of the mechanism.Three methods for structure coupling-reducing of the 3UPS&UP parallel mechanism are proposed,resulting in eight new types of 1T2R parallel mechanisms with one or zero coupling degree.One obtained parallel mechanism is taken as an example to demonstrate that a mechanism with zero coupling degree has an explicit form for forward kinematics.The process of type synthesis is in the order of permutation and combination;therefore,there are no omissions.This method is also appli cable to other configurations,and novel topological structures having simple forward kinematics can be obtained from an original mechanism via this method.
基金supported jointly by the Fostering Plan Fund for Trans-century Excellent Talents and the Key Project of Science and Technology Research of the Ministry of Education(No.03178)the National Natural Science Foundation of China(No.40572063 and No.40234051).
文摘For understanding the possible deep-seated processes and geodynamic constrains on gold mineralization, comprehensive physicochemical and geochemical studies of gold mineralization have been undertaken within the paleo-lithosphere framework during the metailogenic epoch from the northwestern part of the Jiaodong Peninsula in this paper. A general image of the paleo-crust has been remained although it has been superimposed and reformed by post-metailogenic tectonic movements. The gold ore deposits occur usually in local uplifts and gradient belts featuring a turn from steep to gentle in granite-metamorphic contact zones, relative uplifts of gradient zones of the Curier isothermal interfaces, depressions of the Moho discontinuity and areas where depth contours are cut by isotherms perpendicularly. Gold mineralization and lithogenesis are characterized by high temperature, low pressure and high strength of thermal flux. The depth of mineralization ranges from 0.8 to 4.5 km. The depth of the top interface of the granitic complex in the metallogenic epoch is about 3 km. There is a low-velocity layer （LVL） at the bottom of the upper crust with a depth close to 19.5 km, which may be a detachment belt in the crust. The appearance of the LVL indicates the existence of paleo-hyperthermal fluid or relics of molten magma chambers, which reflects partial melting within the crust during the diagenetic and metallogenic epochs and the superposition effects of strike-slip shearing of the Taulu fault zone. The subsidence of the Moho is probably attributed to the coupling process of the NW-SE continental collision between North China and the Yangtze Block and the strike-slip movement of the Tanlu fault accompanied with underplating of mantle magma in the northwestern part of the Jiaodong Peninsula. The underplating of mantle magma may result in partial melting and make granite magma transfer upwards. This is favorable for the migration of metallogenic materials from deep to shallow to be enriched to form deposits. Coupling interactions between the strike-slip of the Taulu fault, the underplating of mantle magma, partial melting within the crust, and hyperthermal fluid, etc. may be the important factors controlling the gold mineralization and spatial structures in the metailogenic system.
基金The MOE Project of Key Research Institute of Humanities and Social Sciences in University,No.14JJD790044Science and Technology Research Program Supported by the Education Department of Liaoning Province,No.L2013411
文摘Using a sample of 14 prefecture-level cities in Liaoning Province, this study first explored the spatial hierarchy and structural characteristics of energy efficiency from the following three viewpoints： energy technical efficiency based on data envelopment analysis, energy consumption per unit of GDP, and energy utilization efficiency combining the previous two indexes After measuring and analyzing the advancement, rationality, and concentration of the industrial structure in each city, we made some generalizations about the coupling features of the energy efficiency and industrial structure in Liaoning, using the coupling degree rating model Some of our conclusions are as follows： （1） The 14 cities differ significantly in their en- ergy efficiency, with Shenyang, Dalian, Anshan, and Jinzhou enjoying the highest energy effi- ciency. Northwestern Liaoning and other heavy-industrial cities such as Fushun and Benxi belong to low-efficiency and high-consumption areas. （2） In areas with higher efficiency, the spatial patterns of the energy technical efficiency, energy consumption per unit of GDP, and energy utilization efficiency are, respectively, ＂π ＂-, ＂Ⅱ＂- and ＂H＂- shaped. Geographically, the energy utilization efficiency shows different trends from east to west and from north to south. Factors such as the binuclear structure of economic development have a major effect on this spatial pattern of energy efficiency. （3） Southeastern Liaoning enjoys a highly advanced in- dustrial structure. Areas with a highly rational industrial structure form an ＂H＂ shape, with Shenyang and Dalian at the two poles. The urban agglomerations in middle and southern Liaoning have a highly concentrated industrial structure. （4） Overall, the coupling between energy efficiency and industrial structure is low in Liaoning, except for Shenyang and Dalian at both ends, where the coupling between an advanced industrial structure and energy efficiency is higher than in other cities.
文摘Based on the results of two dimension velo city structure, 1∶100 000 aeromagnetic anomaly, 1∶200 000 bouguer gravity anom aly and seismic anisotropy of Jiaodong and neighboring region in Shandong, China , the information of geophysical field was divided into two parts: deep and sh allow focus fields. And then, the information of two different fields was c ombined with that of deep seated geology and ore deposit features. The syntheti c result was adopted to analyze three dimension structure, to probe into crust mantle coupling effects of mineralization and dynamics of ore formation system .
基金co-supported by the Excellent Youth Science Foundation of China(No.51722501)the China Postdoctoral Science Foundation(No.2016M600027)+1 种基金the National Natural Science Foundation of China(Nos.51575025 and 61703022)the Preliminary Exploration of Project of China(No.7131474)
文摘With the high speed, the rotor of magnetically suspended permanent magnet synchronous motor(MSPMSM) suffers great thermal stress and mechanical stress resulting from the temperature rise problem caused by rotor losses, which leads to instability and inefficiency.In this paper, the mechanical–temperature field coupling analysis is conducted to analyze the relationship between the temperature field and structure, and multi-objective optimization of a rotor is performed to improve the design reliability and efficiency. Firstly, the temperature field is calculated by the 2 D finite element model of MSPMSM and the method of applying the 2 D temperature result to the 3 D finite element model of the motor rotor equivalently is proposed. Then the thermal–structure coupling analysis is processed through mathematic method and finite element method(FEM),in which the 3 D finite element model is established precisely in a way and approaches the practical operation state further. Moreover, the impact produced by the temperature and structure on the mechanical strength is analyzed in detail. Finally, the optimization mathematical model of the motor rotor is established with Sequential Quadratic Programming-NLPQL selected in the optimization scheme. Through optimization, the strength of the components in the motor rotor increases obviously and satisfies the design requirement, which to a great extend enhances the service life of the MSPMSM rotor.
基金This work was financially supported by the Key Project for National Science of "9.5" (Reward Ⅱ for National Science and Technol
文摘The nonlinear dynamical behaviors of artificial neural network (ANN) and their application to science and engineering were summarized. The mechanism of two kinds of dynamical processes, i.e. weight dynamics and activation dynamics in neural networks, and the stability of computing in structural analysis and design were stated briefly. It was successfully applied to nonlinear neural network to evaluate the stability of underground stope structure in a gold mine. With the application of BP network, it is proven that the neuro-com- puting is a practical and advanced tool for solving large-scale underground rock engineering problems.
基金National Natural Science Foundation of People’s Republic of China under Grant Nos.51178011 and 51778386the Key Fundamental Study Development Project of People’s Republic of China under Grant No.2011CB013602。
文摘The seismic response characteristics of underground structures in saturated soils are investigated.A fully fluid-solid coupling dynamic model is developed and implemented into ABAQUS with a user-defined element to simulate the dynamic behavior of saturated soils.The accuracy of the model is validated using a classic example in literature.The performance of the model is verified by its application on simulating the seismic response characteristics of a subway station built in saturated soils.The merits of the model are demonstrated by comparing the difference of the seismic response of an underground structure in saturated soils between using the fully coupling model and a single-phase medium model.The study finds that the fully coupling model developed herein can simulate the dynamic response characteristics of the underground structures in saturated soils with high accuracy.The seismic response of the underground structure tends to be underestimated by using the single-phase medium model compared with using the fully coupling model,which provides a weaker confining action to the underground structure.
基金Supported by the Natural Science Foundation of Shanghai under Grant No.09ZR1410800the Science Foundation of Key Laboratory of Mathematics Mechanization under Grant No.KLMM0806+1 种基金the Shanghai Leading Academic Discipline Project under Grant No.J50101Key Disciplines of Shanghai Municipality (S30104)
文摘By using a Lie algebra, an integrable couplings of the classicai-Boussinesq hierarchy is obtained. Then, the Hamiltonian structure of the integrable couplings of the classical-Boussinesq is obtained by the quadratic-form identity.
基金co-supported by National Natural Science Foundation of China(21572164,U1504207)the Sino-German Center for Research Promotion(GZ1289).
文摘The determination of natural products stereochemistry remains a formidable task.Residual dipolar couplings(RDCs)induced by anisotropic media are a powerful tool for determination of the stereochemistry of organic molecule in solution.This review will provide a short introduction on RDCs-based methodology for the structural elucidation of natural products.Special attention is given to the current availability of alignment media in organic solvents.The applications of RDCs for structural analysis of some examples of natural products were discussed and summarized.Graphical Abstract This review provides a short introduction on RDCs-based methodology for the structural elucidation of natural products.Special attention is given to the current availability of alignment media in organic solvents.The applications of RDCs for structural analysis of some examples of natural products were discussed and summarized.
基金Supported by the Natural Science Foundation of China under Grant No. 60972164the Program for Liaoning Excellent Talents in University under Grant No. LJQ2011136+2 种基金the Key Technologies R&D Program of Liaoning Province under Grant No. 2011224006the Program for Liaoning Innovative Research Team in University under Grant No. LT2011019the Science and Technology Program of Shenyang under Grant No. F11-264-1-70
文摘We construct nonlinear super integrable couplings of the super integrable Dirac hierarchy based on an enlarged matrix Lie superalgebra.Then its super Hamiltonian structure is furnished by super trace identity.As its reduction,we gain the nonlinear integrable couplings of the classical integrable Dirac hierarchy.
基金Project supported by the National Natural Science Foundation of China(No.11972112)the Fundamental Research Funds for the Central Universities of China(Nos.N2103024 and N2103002)the Major Projects of Aero-Engines and Gasturbines(No.J2019-I-0008-0008)。
文摘The dynamic characteristics of a single liquid-filled pipe have been broadly studied in the previous literature.The parallel liquid-filled pipe(PLFP)system is also widely used in engineering,and its structure is more complex than that of a single pipe.However,there are few reports about the dynamic characteristics of the PLFPs.Therefore,this paper proposes improved frequency modeling and solution for the PLFPs,involving the logical alignment principle and coupled matrix processing.The established model incorporates both the fluid-structure interaction(FSI)and the structural coupling of the PLFPs.The validity of the established model is verified by modal experiments.The effects of some unique parameters on the dynamic characteristics of the PLFPs are discussed.This work provides a feasible method for solving the FSI of multiple pipes in parallel and potential theoretical guidance for the dynamic analysis of the PLFPs in engineering.
文摘Firstly, a vector loop algebra G3 is constructed, by use of it multi-component KN hierarchy is obtained. Further, by taking advantage of the extending vector loop algebras G6 and G9 of G3 the double integrable couplings of the multi-component KN hierarchy are worked out respectively. Finally, Hamiltonian structures of obtained system are given by quadratic-form identity.
基金Project supported by the Scientific Research Fundation of the Education Department of Liaoning Province,China(GrantNo.L2010513)the China Postdoctoral Science Foundation(Grant No.2011M500404)
文摘In this paper, a new nonlinear integrable coupling system of the soliton hierarchy is presented. Prom the Lax pairs, the coupled KdV equations are constructed successfully. Based on the prolongation method of Wahlquist and Estabrook, we study the prolongation structure of the nonlinear integrable couplings of the KdV equation.
基金China Seismological Bureau during the "Ninth Five-Year Plan" period!Key Project(95-04-08-02)
文摘In the light of results from study on coupling between deep and shallow structures in Xingtai earthquake area during the 'Ninth Five-Year Plan' period and other previous results from deep seismic refraction/reflection and seismic prospecting of petroleum, we infer that there exist a series of shallow faults in the upper crust above the 8 km-deep detachment surface in Xingtai macroseismic focal region, where none of the faults, including Aixinzhuang fault reaches the Quaternary stratum, except that the Xinhe fault cuts through the mid-Pleistocene formation upwards. Aixinzhuang fault and other faults extend downwards into Xinhe fault whereas the Xinhe listric fault stretches downwards at a low dip angle into the detachment surface. The abyssal fault with high dip angle under the detachment surface cutting through the middle and lower crust to Moho is the causative fault for the large Xingtai earthquake, whose dislocation can cause strong earthquakes, shallow fault activity and the motion of surface material. The shallow faults in the upper crust are not causative faults for strong earthquakes, although they may be active faults. The existence of the detachment surface brings about a special relationship between shallow and deep structures, i.e. they are relatively independent of each other and have effects on each other It not only transmits partial energy and deformation between the upper and lower crust,but also has a certain decoupling effect. Finally we conclude that active faults do not necessarily reach the latest stratum, and the age of uppermost faulted stratum cannot represent the latest active period of the fault. This put to us a significant question in regard to the age determination and study of active faults. Other noticeable questions are also inferred to in this study.
基金financially supported by the National Natural Science Foundation of China(Grant No.U1906233)the Development Projects in Key Areas of Guangdong Province(Grant No.2020B1111040002)the Fundamental Research Funds for the Central Universities(Grant Nos.DUT20ZD213 and DUT20LAB308)。
文摘This work presents a numerical investigation of the thermal–fluid–structure coupling behavior of the liquid natural gas(LNG)transported in the flexible corrugated cryogenic hose.A three-dimensional model of the corrugated hose structure composed of multiple layers of different materials is established and coupled with turbulent LNG flow and heat transfer models in the commercial software ANSYS Workbench.The flow transport behavior,heat transfer across the hose layers,and structural response caused by the flow are analyzed.Parametric studies are performed to evaluate the impacts of inlet flow rate and thermal conductivity of insulation material on the temperature and structural stress of the corrugated hose.The study found that,compared with a regular operating condition,higher inlet flow velocities not only suppress the heat gain of the LNG but also lower the flow-induced structural stress.The insulation layer exhibits excellent performance in maintaining the temperature at the fluid–structure interface,showing little temperature change with respect to material thermal conductivity and ambient temperature.The simulation results may contribute to the research and design of the flexible corrugated cryogenic hoses and provide guidance for safer and more efficient field operations.
基金supported by the National Natural Science Foundation of China (Grant No. 11774190)。
文摘Ternary transition metal chalcogenides provide a rich platform to search and study intriguing electronic properties. Using angle-resolved photoemission spectroscopy and ab initio calculation, we investigate the electronic structure of Cu_(2)TlX_(2)(X = Se, Te), ternary transition metal chalcogenides with quasi-two-dimensional crystal structure. The band dispersions near the Fermi level are mainly contributed by the Te/Se p orbitals. According to our ab-initio calculation, the electronic structure changes from a semiconductor with indirect band gap in Cu_(2)TlSe_(2) to a semimetal in Cu_(2)TlTe_(2), suggesting a band-gap tunability with the composition of Se and Te. By comparing ARPES experimental data with the calculated results, we identify strong modulation of the band structure by spin–orbit coupling in the compounds. Our results provide a ternary platform to study and engineer the electronic properties of transition metal chalcogenides related to large spin–orbit coupling.
基金supported by the Innovation Fund for Chemistry of NWO,grant number 731.014.303by SASOL。
文摘The effect of temperature and hydrogen addition on undesired carbonaceous deposit formation during methane coupling was studied in DBD-plasma catalytic-wall reactors with Pd/Al2 O3, using electrical power to drive the reaction.Experiments with thin catalyst layers allowed comparison of the performance of empty reactors and catalytic wall reactors without significantly influencing the plasma properties.The product distribution varies strongly in the temperature window between 25 and 200℃Minimal formation of deposits is found at an optimal temperature around 75℃ in the catalytic-wall reactors.The selectivity to deposits was c.a.10% with only 9 mg of catalyst loading instead of 45% in the blank reactor,while decreasing methane conversion only mildly.Co-feeding H2 to an empty reactor causes a similar decrease in selectivity to deposits,but in this case methane conversion also decreased significantly.Suppression of deposits formation in the catalytic-wall reactor at 75℃ is due to catalytic hydrogenation of mainly acetylene to ethylene.In the empty reactor,H2 co-feed decreases conversion but does not change the product distribution.The catalytic-wall reactors can be regenerated with H2-plasma at room temperature,which produces more added-value hydrocarbons.
