A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300...A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding）, the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures.展开更多
That the Chinese economy has been burgeoning for nearly 30 years is an irrefutable fact.However,this robust growth has been achieved amidst accusations of"extensive"development and"low-efficiency"....That the Chinese economy has been burgeoning for nearly 30 years is an irrefutable fact.However,this robust growth has been achieved amidst accusations of"extensive"development and"low-efficiency".Many scholars believe that low-priced labour is pivotal to China’s rapid growth.Even so,we find it hard to explain why China has been able to achieve sustained growth while so many countries with even lower labour costs remain trapped in poverty The following article offers a new perspective upon this paradox.展开更多
Coal mining has changed the hydrogeological conditions of river basins,and studying how the relationship among different types of water body has changed under the influence of coal mining is of great significance for ...Coal mining has changed the hydrogeological conditions of river basins,and studying how the relationship among different types of water body has changed under the influence of coal mining is of great significance for understanding the regional hydrological cycle.We analyzed the temporal and spatial distribution of hydrochemical properties and environmental isotopes in the Hailiutu River Basin(HRB),China with a mixed model.The results showed that:(1)human activity(e.g.,coal mining and agricultural production)causes considerable changes in the hydrochemical properties of surface water in and around the mining areas,and leads to significant increases in the concentrations of Na^(+)and SO_(4)^(2-);(2)precipitation is the main source of water vapour in the HRB.The transformation between surface water and groundwater in the natural watershed is mainly affected by precipitation;and(3)in the mining areas,the average contribution rates of precipitation to the recharge of surface water and groundwater increased by 2.6%-7.9%and 2.7%-9.9%,respectively.Groundwater in the Salawusu Formation constitutes up to 61.3%-72.4%of mine water.Overall,this study is beneficial for quantifying the effects of coal mining on local hydrological cycles.The research results can provide a reference for local water resources management and ecological environment improvement.展开更多
Reliability allocation of computerized numerical controlled（CNC）lathes is very important in industry.Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate compon...Reliability allocation of computerized numerical controlled（CNC）lathes is very important in industry.Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate components,which is not applicable in some conditions.Aiming at solving the problem of CNC lathes reliability allocating,a comprehensive reliability allocation method based on cubic transformed functions of failure modes and effects analysis（FMEA）is presented.Firstly,conventional reliability allocation methods are introduced.Then the limitations of direct combination of comprehensive allocation method with the exponential transformed FMEA method are investigated.Subsequently,a cubic transformed function is established in order to overcome these limitations.Properties of the new transformed functions are discussed by considering the failure severity and the failure occurrence.Designers can choose appropriate transform amplitudes according to their requirements.Finally,a CNC lathe and a spindle system are used as an example to verify the new allocation method.Seven criteria are considered to compare the results of the new method with traditional methods.The allocation results indicate that the new method is more flexible than traditional methods.By employing the new cubic transformed function,the method covers a wider range of problems in CNC reliability allocation without losing the advantages of traditional methods.展开更多
To investigate the influence of the bedding angle,β,on the mechanical properties and rockburst proneness,uniaxial compression tests were conducted using cylindrical phyllite specimens with different bedding angles.Ac...To investigate the influence of the bedding angle,β,on the mechanical properties and rockburst proneness,uniaxial compression tests were conducted using cylindrical phyllite specimens with different bedding angles.According to the results,the peak stress,peak strain,cumulative acoustic emission counts,and potential energy of the elastic strain exhibited a U-shaped change trend.With an increase in β from 0°to 90°,the failure mode transformed from tensile splitting failure along the bedding plane to shear slip failure along the weak bedding plane.Finally,the failure mode evolved into a tensile splitting failure across the bedding plane.When β=15°,30°,and 45°,the phyllite specimens exhibited strong,slight,and moderate rockburst proneness,with strong,slight,and moderate shear slip rockbursts,respectively.When β=0°,60°,75°,and 90°,the phyllite specimens had extremely strong rockburst proneness,and an extremely strong strain rockburst occurred.展开更多
This research focuses on measuring the mode transformation and energy attenuation of wedge waves for different apex angle wedges by using laser ultrasound techniques.Pulsed laser excitation and optical deflection beam...This research focuses on measuring the mode transformation and energy attenuation of wedge waves for different apex angle wedges by using laser ultrasound techniques.Pulsed laser excitation and optical deflection beam methods for detection were used to measure the wedge waves.In experiment,various wedge waves at different locations were recorded by scanning the excitation laser along the wedge tip,and different orders of wedge waves were observed.By fixing the distance between the excitation and detection positions and scanning the samples along the direction normal to the wedge tip,the modes transformation process was obtained.It was found that the energy of the acoustic waves for 20°,25° and 30° wedges decreased exponentially to a steady energy of Rayleigh wave within the main wavelength range of the acoustic modes,while the energy of acoustic waves of 45° and 60° wedge remained stable as the propagation line was scanned away from the wedge tip.展开更多
In order to deploy the crucial levers in the transformation of the Chinese mode of economic development, it is necessary to identify the nature and reasons for the economy＇s existing mode of operation. The paradox of...In order to deploy the crucial levers in the transformation of the Chinese mode of economic development, it is necessary to identify the nature and reasons for the economy＇s existing mode of operation. The paradox of China＇s ＂double surplus＂ in the international balance of payments reflects the substantive issue of the appearance of a capability gap in Chinese economic development, which, interacting with dependence on FDI, hinders industry upgrading. As a result, the extensive mode of development has persisted and even worsened, rendering the Chinese economy more vulnerable to external shocks. At the historic juncture when the international economic environment is undergoing dramatic changes, the Chinese economy is likely to suffer severe setbacks due to its capability gap and dependence on FDI unless there is substantial development in its technological and organizational capacities and institution-building. Therefore, the critical variable in transforming the Chinese mode of economic development is capability growth.展开更多
It has been found that the brittle material, monocrystalline silicon, can be machined in ductile mode in nanoscale cutting when the tool cutting edge radius is reduced to nanoscale and the undeformed chip thickness is...It has been found that the brittle material, monocrystalline silicon, can be machined in ductile mode in nanoscale cutting when the tool cutting edge radius is reduced to nanoscale and the undeformed chip thickness is smaller than the tool edge radius. In order to better understand the mechanism of ductile mode cutting of silicon, the molecular dynamics （MD） method is employed to simulate the nanoscale cutting of monocrystalline silicon. The simulated variation of the cutting forces with the tool cutting edge radius is compared with the cutting force results from experimental cutting tests and they show a good agreement. The results also indicate that there is silicon phase transformation from monocrystalline to amorphous in the chip formation zone that can be used to explain the cause of ductile mode cutting. Moreover, from the simulated stress results, the two necessary conditions of ductile mode cutting, the tool cutting edge radius are reduced to nanoscale and the undeformed chip thickness should be smaller than the tool cutting edge radius, have been explained.展开更多
Motor impedance and mode transformation have significant effects on the electromagnetic interference(EMI)generated in motor drive systems.Stator winding faults commonly cause motor failure;however,in their early stage...Motor impedance and mode transformation have significant effects on the electromagnetic interference(EMI)generated in motor drive systems.Stator winding faults commonly cause motor failure;however,in their early stages,they may not affect the short-term operation of the motor.To date,EMI noise under the influence of premature stator winding faults has not been adequately studied,particularly the differential-mode(DM)noise due to the common-mode(CM)-to-DM transformation.This study investigates and quantifies the influence of stator winding faults on the motor DM impedance and mode transformation.First,the transmission line model of an induction motor is described based on the scattering(S)parameter measurements of each phase of the motor.It offers the flexibility to emulate different types of stator winding faults at specific locations and various severities,such that the impacts of the faults on the motor DM impedance can be easily estimated.Second,a test setup is proposed to quantify the CM-to-DM transformation due to the stator winding faults.The findings of this study reveal that even the early stages of stator winding faults can result in significant changes in the DM noise.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10674009, 10521002 and 10434020)the National Key Development Program for Basic Research of China (Grant No 2007CB307001)
文摘A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding）, the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures.
文摘That the Chinese economy has been burgeoning for nearly 30 years is an irrefutable fact.However,this robust growth has been achieved amidst accusations of"extensive"development and"low-efficiency".Many scholars believe that low-priced labour is pivotal to China’s rapid growth.Even so,we find it hard to explain why China has been able to achieve sustained growth while so many countries with even lower labour costs remain trapped in poverty The following article offers a new perspective upon this paradox.
基金This research was supported by the National Key Research and Development Program of China(2018YFC0406401)the Inner Mongolia Autonomous Region“Grassland Talents”Project.
文摘Coal mining has changed the hydrogeological conditions of river basins,and studying how the relationship among different types of water body has changed under the influence of coal mining is of great significance for understanding the regional hydrological cycle.We analyzed the temporal and spatial distribution of hydrochemical properties and environmental isotopes in the Hailiutu River Basin(HRB),China with a mixed model.The results showed that:(1)human activity(e.g.,coal mining and agricultural production)causes considerable changes in the hydrochemical properties of surface water in and around the mining areas,and leads to significant increases in the concentrations of Na^(+)and SO_(4)^(2-);(2)precipitation is the main source of water vapour in the HRB.The transformation between surface water and groundwater in the natural watershed is mainly affected by precipitation;and(3)in the mining areas,the average contribution rates of precipitation to the recharge of surface water and groundwater increased by 2.6%-7.9%and 2.7%-9.9%,respectively.Groundwater in the Salawusu Formation constitutes up to 61.3%-72.4%of mine water.Overall,this study is beneficial for quantifying the effects of coal mining on local hydrological cycles.The research results can provide a reference for local water resources management and ecological environment improvement.
基金Supported by National Natural Science Foundation of China(Grant Nos.51135003,51205050,U1234208)Key National Science & Technology Special Project on"High-Grade CNC Machine Tools and Basic Manufacturing Equipments"(Grant No.2013ZX04011011)+1 种基金Research Fund for the Doctoral Program of Higher Education of China(Grant No.20110042120020)Fundamental Research Funds for the Central
文摘Reliability allocation of computerized numerical controlled（CNC）lathes is very important in industry.Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate components,which is not applicable in some conditions.Aiming at solving the problem of CNC lathes reliability allocating,a comprehensive reliability allocation method based on cubic transformed functions of failure modes and effects analysis（FMEA）is presented.Firstly,conventional reliability allocation methods are introduced.Then the limitations of direct combination of comprehensive allocation method with the exponential transformed FMEA method are investigated.Subsequently,a cubic transformed function is established in order to overcome these limitations.Properties of the new transformed functions are discussed by considering the failure severity and the failure occurrence.Designers can choose appropriate transform amplitudes according to their requirements.Finally,a CNC lathe and a spindle system are used as an example to verify the new allocation method.Seven criteria are considered to compare the results of the new method with traditional methods.The allocation results indicate that the new method is more flexible than traditional methods.By employing the new cubic transformed function,the method covers a wider range of problems in CNC reliability allocation without losing the advantages of traditional methods.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(Nos.51904335,11972378,41630642)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2019zzts310).
文摘To investigate the influence of the bedding angle,β,on the mechanical properties and rockburst proneness,uniaxial compression tests were conducted using cylindrical phyllite specimens with different bedding angles.According to the results,the peak stress,peak strain,cumulative acoustic emission counts,and potential energy of the elastic strain exhibited a U-shaped change trend.With an increase in β from 0°to 90°,the failure mode transformed from tensile splitting failure along the bedding plane to shear slip failure along the weak bedding plane.Finally,the failure mode evolved into a tensile splitting failure across the bedding plane.When β=15°,30°,and 45°,the phyllite specimens exhibited strong,slight,and moderate rockburst proneness,with strong,slight,and moderate shear slip rockbursts,respectively.When β=0°,60°,75°,and 90°,the phyllite specimens had extremely strong rockburst proneness,and an extremely strong strain rockburst occurred.
基金supported by the National Natural Science Foundation of China (Grant Nos. 60878023 and 61108013)the program for New Century Excellent Talents in University (NCET)the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘This research focuses on measuring the mode transformation and energy attenuation of wedge waves for different apex angle wedges by using laser ultrasound techniques.Pulsed laser excitation and optical deflection beam methods for detection were used to measure the wedge waves.In experiment,various wedge waves at different locations were recorded by scanning the excitation laser along the wedge tip,and different orders of wedge waves were observed.By fixing the distance between the excitation and detection positions and scanning the samples along the direction normal to the wedge tip,the modes transformation process was obtained.It was found that the energy of the acoustic waves for 20°,25° and 30° wedges decreased exponentially to a steady energy of Rayleigh wave within the main wavelength range of the acoustic modes,while the energy of acoustic waves of 45° and 60° wedge remained stable as the propagation line was scanned away from the wedge tip.
文摘In order to deploy the crucial levers in the transformation of the Chinese mode of economic development, it is necessary to identify the nature and reasons for the economy＇s existing mode of operation. The paradox of China＇s ＂double surplus＂ in the international balance of payments reflects the substantive issue of the appearance of a capability gap in Chinese economic development, which, interacting with dependence on FDI, hinders industry upgrading. As a result, the extensive mode of development has persisted and even worsened, rendering the Chinese economy more vulnerable to external shocks. At the historic juncture when the international economic environment is undergoing dramatic changes, the Chinese economy is likely to suffer severe setbacks due to its capability gap and dependence on FDI unless there is substantial development in its technological and organizational capacities and institution-building. Therefore, the critical variable in transforming the Chinese mode of economic development is capability growth.
基金Selected from Proceedings of the 7th International Conference on Frontiers of DesignManufacturing(ICFDM'2006).
文摘It has been found that the brittle material, monocrystalline silicon, can be machined in ductile mode in nanoscale cutting when the tool cutting edge radius is reduced to nanoscale and the undeformed chip thickness is smaller than the tool edge radius. In order to better understand the mechanism of ductile mode cutting of silicon, the molecular dynamics （MD） method is employed to simulate the nanoscale cutting of monocrystalline silicon. The simulated variation of the cutting forces with the tool cutting edge radius is compared with the cutting force results from experimental cutting tests and they show a good agreement. The results also indicate that there is silicon phase transformation from monocrystalline to amorphous in the chip formation zone that can be used to explain the cause of ductile mode cutting. Moreover, from the simulated stress results, the two necessary conditions of ductile mode cutting, the tool cutting edge radius are reduced to nanoscale and the undeformed chip thickness should be smaller than the tool cutting edge radius, have been explained.
文摘Motor impedance and mode transformation have significant effects on the electromagnetic interference(EMI)generated in motor drive systems.Stator winding faults commonly cause motor failure;however,in their early stages,they may not affect the short-term operation of the motor.To date,EMI noise under the influence of premature stator winding faults has not been adequately studied,particularly the differential-mode(DM)noise due to the common-mode(CM)-to-DM transformation.This study investigates and quantifies the influence of stator winding faults on the motor DM impedance and mode transformation.First,the transmission line model of an induction motor is described based on the scattering(S)parameter measurements of each phase of the motor.It offers the flexibility to emulate different types of stator winding faults at specific locations and various severities,such that the impacts of the faults on the motor DM impedance can be easily estimated.Second,a test setup is proposed to quantify the CM-to-DM transformation due to the stator winding faults.The findings of this study reveal that even the early stages of stator winding faults can result in significant changes in the DM noise.
