A photonic crystal nanobeam cavity(M-PCNC)with a structure incorporating a mixture of diamond-shaped and circular air holes is pro-posed.The performance of the cavity is simulated and studied theoretically.Using thefin...A photonic crystal nanobeam cavity(M-PCNC)with a structure incorporating a mixture of diamond-shaped and circular air holes is pro-posed.The performance of the cavity is simulated and studied theoretically.Using thefinite-difference time-domain method,the parameters of the M-PCNC,including cavity thickness and width,lattice constant,and radii and numbers of holes,are optimized,with the quality factor Q and mode volume Vm as performance indicators.Mutual modulation of the lattice constant and hole radius enable the proposed M-PCNC to realize outstanding performance.The optimized cavity possesses a high quality factor Q 1.45105 and an ultra-small mode=×volume Vm 0.01(λ/n)[Zeng et al.,Opt Lett 2023:48;3981–3984]in the telecommunications wavelength range.Light can be progres-=sively squeezed in both the propagation direction and the perpendicular in-plane direction by a series of interlocked anti-slots and slots in the diamond-shaped hole structure.Thereby,the energy can be confined within a small mode volume to achieve an ultra-high Q/Vm ratio.展开更多
Considering the shortcomings of the existing vehicle-to-vehicle（V2V） communication antennas, this paper proposes a regular hexagon broadband microstrip antenna. By loading shorting pins and etching V-shape slots wit...Considering the shortcomings of the existing vehicle-to-vehicle（V2V） communication antennas, this paper proposes a regular hexagon broadband microstrip antenna. By loading shorting pins and etching V-shape slots with different size at each angle of the regular hexagon patch, it realizes impedance matching and obtains better impedance bandwidth. The simulated results show that the relative bandwidth of this antenna reaches 35.55%, covers the frequency band of 4.74 GHz to 6.79 GHz. The antenna acquires an omni-directional radiation pattern in the horizontal plane whose out of roundness is less than 0.5 d B. In addition, the antenna is manufactured and tested, whose tested results are basically consistent with simulated results. Because the height of antenna is 3 mm, it is easy to be hidden on roof of a vehicle for V2 V communication.展开更多
Mechanical agitation in baffled vessels with turbines plays a vital role in achieving homogeneous fluid mixing and promoting various transfer operations.Therefore,designing vessels with optimal energy efficiency and f...Mechanical agitation in baffled vessels with turbines plays a vital role in achieving homogeneous fluid mixing and promoting various transfer operations.Therefore,designing vessels with optimal energy efficiency and flow dynamics is essential to enhance operational performance and eliminate flow perturbations.Hence,the present research focuses on a numerical investigation of the impact of inclined slots with different angles installed at the side-wall of a cylindrical vessel equipped with a Rushton turbine.This study explores power consumption and vortex size while considering various rotation directions of the impeller with different rotation speeds.The numerical simulations are conducted for Reynolds numbers ranging from 104 to 105,using the RANS k-εturbulence model to govern the flow inside the stirred vessel,accounting for mass and momentum balances.The results have shown that the installation of slots reduces power consumption and vortex size compared to conventional vessel configu-rations.Moreover,increasing the slot angle from 0 to 32.5°further reduces energy consumption and vortex size,especially with negative rotation speeds.On the other hand,increasing the Reynolds numbers leads to a decrease in power consumption and an increase in vortex size.The present research therefore proposes a design for con-structing Rushton-turbine stirred vessels offering optimal operation,characterized by reduced energy consumption and minimized vortex size.展开更多
In this paper, two different designs, with dummy slots and bread-loaf magnets techniques, are presented to reduce the electromagnetic vibration in integral-slot surface-mounted permanent-magnet(SPM) machines. Firstly,...In this paper, two different designs, with dummy slots and bread-loaf magnets techniques, are presented to reduce the electromagnetic vibration in integral-slot surface-mounted permanent-magnet(SPM) machines. Firstly, the stator slotting effect on the magnetic field modulation and radial force modulation is investigated. It reveals the amplitude of the modulated magnetic field and modulated radial force is greatly affected by the slot opening effect, while the spatial order is closely associated with the slot numbers. Subsequently, the dummy slots and bread-loaf magnets design are developed for a 36-slot/12-pole integral-slot SPM machine to reduce the electromagnetic vibration. Finally, two SPM machines, with conventional and bread-loaf magnets,are manufactured. Experimental tests are carried out to validate the theoretical analyses.展开更多
Effects of tip slots on the aerodynamic characteristics of helicopter rotor were investigated numerically by solving three-dimensional Navier-Stokes equations based on unstructured overset grids algorithm.Improved del...Effects of tip slots on the aerodynamic characteristics of helicopter rotor were investigated numerically by solving three-dimensional Navier-Stokes equations based on unstructured overset grids algorithm.Improved delayed detached eddy simulation (IDDES) based on the Spalart-Allmaras turbulence model and adaptive grid refinement technique were employed.Several slots in the rotor blade tip were designed on the base of Caradonna-Tung rotor to study the effect of tip slots.Numerical results show that tip slots are able to introduce the airflow from the leading edge and turn it in the spanwise direction to be ejected out of the face at the rotor blade tip,which can reduce the strength of the rotor blade tip vortex and accelerate the dissipation process.Although tip slots may lead to the decrease of airfoils' lift coefficient at the root of the rotor blade,it can increase the lift coefficient of airfoils at the rotor blade tip,so the lift of the rotor with tip slots is almost the same as that of the rotor without tip slots.In addition,tip slots can also reduce the intensity of the tip shock wave,which is beneficial to reduce the wave drag of the rotor.展开更多
A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSF...A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSFAA is designed on FR4 substrate material with permittivity 4.4 and height 1.6 mm. PSFAA is designed up to 2nd iteration. High Frequency Structure Simulator (HFSS) software is used for simulation of PSFAA. The proposed antenna array operates at three bands with five frequencies 2.5 GHz, 4.1 GHz, 6.9 GHz, 7.4 GHz and 8.2 GHz. Simulated Return losses results of proposed PSFAA are -22.15 dB, -19.44 dB, -25.21 dB, -10 dB, -12.45 dB at above frequencies respectively. It has a gain of 9.22 dB at resonant frequency 2.5 GHz whereas conventional antenna array has a gain of 5.15 dB at resonant frequency 2.5 GHz. Return losses and gain of PSFAA also improved from conventional antenna array at various resonant frequencies.展开更多
The distortion of mold plates plays an important role in the formation of surface cracks on continuously cast steel products. To investigate the non-uniform distortion of a mold, a full-scale stress model of the mold ...The distortion of mold plates plays an important role in the formation of surface cracks on continuously cast steel products. To investigate the non-uniform distortion of a mold, a full-scale stress model of the mold was de veloped. An inverse algorithm was applied to calculate the heat flux using the temperatures measured by the thermo- couples buried inside the mold plates. Based on this, a full-scale, finite-element stress model, including four copper plates, a nickel layer and water slots in different depths, was built to determine the complex mechanical behavior of the continuous casting mold used to produce steel slabs. The heat flux calculated by the inverse algorithm was applied to the stress model to analyze the non-uniform mechanical behavior. The results showed that the stress and distortion distributions of the four copper plates were not symmetrical, which reflected the non-uniform distortion behaviors of copper plates, water slots, nickel layer and the corner region of the mold. The gap between the mold and the slab was increased because of the corner distortion, which was very important for the heat transfer of initial solidifying shell, and it may be a major reason for the slow cooling of the slab corner.展开更多
The photo-elastic method has been employed to determine stress concentration factor (SCF) for square plates containing holes and inclined slots when the plate edges are subjected to in-plane tension combined with comp...The photo-elastic method has been employed to determine stress concentration factor (SCF) for square plates containing holes and inclined slots when the plate edges are subjected to in-plane tension combined with compression. Analyses given of the isochromatic fringe pattern surrounding the hole provides the SCF conveniently. The model material is calibrated from the known solution to the stress raiser arising from a small circular hole in a plate placed under biaxial tension-compression. These results also compare well with a plane stress FE analysis. Consequently, photo-elasticity has enabled SCF’s to be determined experimentally for a biaxial stress ratio, nominally equal to –4, in plates containing a long, thin slot arranged to be in alignment with each stress axis. The two, principal stresses lying along axes of symmetry in the region surrounding the notch are separated within each isochromatic fringe by the Kuske method [1]. FE provides a comparable full-field view in which contours of maximum shear stress may be identified with the isochromatic fringe pattern directly. The principal stress distributions referred to the plate axes show their maximum concentrations at the notch boundary. Here up to a fourfold magnification occurs in the greater of the two nominal stresses under loads applied to the plate edges. Thus, it is of importance to establish the manner in which the tangential stress is distributed around the slot boundary. Conveniently, it is shown how this distribution is also revealed from an isochro-matic fringe pattern, within which lie the points of maximum tension and maximum compression.展开更多
基金supported by the Open Fund of the State Key Laboratory of Advanced Optical Communication Systems and Networks (SJTU)(Grant No. 2023GZKF018)the Open Fund of IPOC (BUPT)(Grant No. IPOC2021B03)+4 种基金the National Natural Science Foundation of China (NSFC)(Grant No. 11974188)the China Postdoctoral Science Foundation (Grant Nos. 2021T140339 and 2018M632345)the Jiangsu Province Postdoctoral Science Foundation (Grant No. 2021K617C)the Postgraduate Research and Practice Innovation Program of Jiangsu Province (Grant No.KYCX22_0945)the Qing Lan Project of Jiangsu Province
文摘A photonic crystal nanobeam cavity(M-PCNC)with a structure incorporating a mixture of diamond-shaped and circular air holes is pro-posed.The performance of the cavity is simulated and studied theoretically.Using thefinite-difference time-domain method,the parameters of the M-PCNC,including cavity thickness and width,lattice constant,and radii and numbers of holes,are optimized,with the quality factor Q and mode volume Vm as performance indicators.Mutual modulation of the lattice constant and hole radius enable the proposed M-PCNC to realize outstanding performance.The optimized cavity possesses a high quality factor Q 1.45105 and an ultra-small mode=×volume Vm 0.01(λ/n)[Zeng et al.,Opt Lett 2023:48;3981–3984]in the telecommunications wavelength range.Light can be progres-=sively squeezed in both the propagation direction and the perpendicular in-plane direction by a series of interlocked anti-slots and slots in the diamond-shaped hole structure.Thereby,the energy can be confined within a small mode volume to achieve an ultra-high Q/Vm ratio.
基金supported by the Science and Technology Research Project of Chongqing Municipal Education Commission(KJ1400417,KJ130531)
文摘Considering the shortcomings of the existing vehicle-to-vehicle（V2V） communication antennas, this paper proposes a regular hexagon broadband microstrip antenna. By loading shorting pins and etching V-shape slots with different size at each angle of the regular hexagon patch, it realizes impedance matching and obtains better impedance bandwidth. The simulated results show that the relative bandwidth of this antenna reaches 35.55%, covers the frequency band of 4.74 GHz to 6.79 GHz. The antenna acquires an omni-directional radiation pattern in the horizontal plane whose out of roundness is less than 0.5 d B. In addition, the antenna is manufactured and tested, whose tested results are basically consistent with simulated results. Because the height of antenna is 3 mm, it is easy to be hidden on roof of a vehicle for V2 V communication.
文摘Mechanical agitation in baffled vessels with turbines plays a vital role in achieving homogeneous fluid mixing and promoting various transfer operations.Therefore,designing vessels with optimal energy efficiency and flow dynamics is essential to enhance operational performance and eliminate flow perturbations.Hence,the present research focuses on a numerical investigation of the impact of inclined slots with different angles installed at the side-wall of a cylindrical vessel equipped with a Rushton turbine.This study explores power consumption and vortex size while considering various rotation directions of the impeller with different rotation speeds.The numerical simulations are conducted for Reynolds numbers ranging from 104 to 105,using the RANS k-εturbulence model to govern the flow inside the stirred vessel,accounting for mass and momentum balances.The results have shown that the installation of slots reduces power consumption and vortex size compared to conventional vessel configu-rations.Moreover,increasing the slot angle from 0 to 32.5°further reduces energy consumption and vortex size,especially with negative rotation speeds.On the other hand,increasing the Reynolds numbers leads to a decrease in power consumption and an increase in vortex size.The present research therefore proposes a design for con-structing Rushton-turbine stirred vessels offering optimal operation,characterized by reduced energy consumption and minimized vortex size.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51991383 and 52025073)。
文摘In this paper, two different designs, with dummy slots and bread-loaf magnets techniques, are presented to reduce the electromagnetic vibration in integral-slot surface-mounted permanent-magnet(SPM) machines. Firstly, the stator slotting effect on the magnetic field modulation and radial force modulation is investigated. It reveals the amplitude of the modulated magnetic field and modulated radial force is greatly affected by the slot opening effect, while the spatial order is closely associated with the slot numbers. Subsequently, the dummy slots and bread-loaf magnets design are developed for a 36-slot/12-pole integral-slot SPM machine to reduce the electromagnetic vibration. Finally, two SPM machines, with conventional and bread-loaf magnets,are manufactured. Experimental tests are carried out to validate the theoretical analyses.
基金supported by the Natural Science Foundation of Fujian Province of China(No.2016J01029)the Aeronautical Science Foundation of China(No.20155768007)the National Natural Science Foundation of China(No.11602209)
文摘Effects of tip slots on the aerodynamic characteristics of helicopter rotor were investigated numerically by solving three-dimensional Navier-Stokes equations based on unstructured overset grids algorithm.Improved delayed detached eddy simulation (IDDES) based on the Spalart-Allmaras turbulence model and adaptive grid refinement technique were employed.Several slots in the rotor blade tip were designed on the base of Caradonna-Tung rotor to study the effect of tip slots.Numerical results show that tip slots are able to introduce the airflow from the leading edge and turn it in the spanwise direction to be ejected out of the face at the rotor blade tip,which can reduce the strength of the rotor blade tip vortex and accelerate the dissipation process.Although tip slots may lead to the decrease of airfoils' lift coefficient at the root of the rotor blade,it can increase the lift coefficient of airfoils at the rotor blade tip,so the lift of the rotor with tip slots is almost the same as that of the rotor without tip slots.In addition,tip slots can also reduce the intensity of the tip shock wave,which is beneficial to reduce the wave drag of the rotor.
文摘A new technique which is a combination of fractal antenna and array antenna is presented to design Plus Slotted Fractal Antenna Array (PSFAA) in this paper. PSFAA with corporate feed operates at 2.5 GHz frequency. PSFAA is designed on FR4 substrate material with permittivity 4.4 and height 1.6 mm. PSFAA is designed up to 2nd iteration. High Frequency Structure Simulator (HFSS) software is used for simulation of PSFAA. The proposed antenna array operates at three bands with five frequencies 2.5 GHz, 4.1 GHz, 6.9 GHz, 7.4 GHz and 8.2 GHz. Simulated Return losses results of proposed PSFAA are -22.15 dB, -19.44 dB, -25.21 dB, -10 dB, -12.45 dB at above frequencies respectively. It has a gain of 9.22 dB at resonant frequency 2.5 GHz whereas conventional antenna array has a gain of 5.15 dB at resonant frequency 2.5 GHz. Return losses and gain of PSFAA also improved from conventional antenna array at various resonant frequencies.
基金Item Sponsored by National Natural Science Foundation of China(51474047,51004012)China Postdoctoral Science Foundation(2012M520621,2013T60511)Fundamental Research Funds for the Central Universities of China
文摘The distortion of mold plates plays an important role in the formation of surface cracks on continuously cast steel products. To investigate the non-uniform distortion of a mold, a full-scale stress model of the mold was de veloped. An inverse algorithm was applied to calculate the heat flux using the temperatures measured by the thermo- couples buried inside the mold plates. Based on this, a full-scale, finite-element stress model, including four copper plates, a nickel layer and water slots in different depths, was built to determine the complex mechanical behavior of the continuous casting mold used to produce steel slabs. The heat flux calculated by the inverse algorithm was applied to the stress model to analyze the non-uniform mechanical behavior. The results showed that the stress and distortion distributions of the four copper plates were not symmetrical, which reflected the non-uniform distortion behaviors of copper plates, water slots, nickel layer and the corner region of the mold. The gap between the mold and the slab was increased because of the corner distortion, which was very important for the heat transfer of initial solidifying shell, and it may be a major reason for the slow cooling of the slab corner.
文摘The photo-elastic method has been employed to determine stress concentration factor (SCF) for square plates containing holes and inclined slots when the plate edges are subjected to in-plane tension combined with compression. Analyses given of the isochromatic fringe pattern surrounding the hole provides the SCF conveniently. The model material is calibrated from the known solution to the stress raiser arising from a small circular hole in a plate placed under biaxial tension-compression. These results also compare well with a plane stress FE analysis. Consequently, photo-elasticity has enabled SCF’s to be determined experimentally for a biaxial stress ratio, nominally equal to –4, in plates containing a long, thin slot arranged to be in alignment with each stress axis. The two, principal stresses lying along axes of symmetry in the region surrounding the notch are separated within each isochromatic fringe by the Kuske method [1]. FE provides a comparable full-field view in which contours of maximum shear stress may be identified with the isochromatic fringe pattern directly. The principal stress distributions referred to the plate axes show their maximum concentrations at the notch boundary. Here up to a fourfold magnification occurs in the greater of the two nominal stresses under loads applied to the plate edges. Thus, it is of importance to establish the manner in which the tangential stress is distributed around the slot boundary. Conveniently, it is shown how this distribution is also revealed from an isochro-matic fringe pattern, within which lie the points of maximum tension and maximum compression.
