Acoustic-resolution photoacoustic microscopy(AR-PAM)suffers from degraded lateral resolution due to acoustic diffraction.Here,a resolution enhancement strategy for AR-PAM via a mean-reverting diffusion model was propo...Acoustic-resolution photoacoustic microscopy(AR-PAM)suffers from degraded lateral resolution due to acoustic diffraction.Here,a resolution enhancement strategy for AR-PAM via a mean-reverting diffusion model was proposed to achieve the transition from acoustic resolution to optical resolution.By modeling the degradation process from high-resolution image to low-resolution AR-PAM image with stable Gaussian noise(i.e.,mean state),a mean-reverting diffusion model is trained to learn prior information of the data distribution.Then the learned prior is employed to generate a high-resolution image from the AR-PAM image by iteratively sampling the noisy state.The performance of the proposed method was validated utilizing the simulated and in vivo experimental data under varying lateral resolutions and noise levels.The results show that an over 3.6-fold enhancement in lateral resolution was achieved.The image quality can be effectively improved,with a notable enhancement of∼66%in PSNR and∼480%in SSIM for in vivo data.展开更多
Boundary layer suction is an e ective method used to delay separations in axial compressors. Most studies on bound?ary layer suction have focused on improving the performance of compressors,whereas few studies investi...Boundary layer suction is an e ective method used to delay separations in axial compressors. Most studies on bound?ary layer suction have focused on improving the performance of compressors,whereas few studies investigated the influence on details of the flow fields,especially vortexes in compressors. CFD method is validated with experi?mental data firstly. Three single?slot and one double?slot endwall boundary layer suction schemes are designed and investigated. In addition to the investigation of aerodynamic performance of the cascades with and without suction,variations in corner open separation,passage vortex,and concentration shedding vortex,which are rarely seen for the flow controlled blades in published literatures,are analyzed. Then,flow models,which are the ultimate aim,of both baseline and aspirated cascades are established. Results show that single?slot endwall suction scheme adjacent to the suction surface can e ectively remove the corner open separation. With suction mass flow rate of 0.85%,the overall loss coe cient and endwall loss coe cient of the cascade are reduced by 25.2% and 48.6%,respectively. Besides,this scheme increases the static pressure rise coe cient of the cascade by 3.2% and the flow turning angle of up to 3.3° at 90% span. The concentration shedding vortex decreases,whereas the passage vortex increases. For single?slot suction schemes near the middle pitchwise of the passage,the concentration shedding vortex increases and the passage vortex is divided into two smaller passage vortexes,which converge into a single?passage vortex near the trailing edge section of the cascade. For the double?slot suction scheme,triple?passage vortexes are presented in the blade passage. Some new vortex structures are discovered,and the novel flow models of aspirated compressor cascade are proposed,which are important to improve the design of multi?stage aspirated compressors.展开更多
A novel solid-liquid interdiffusion(SLID)bonding method with the assistance of temperature gradient(TG)was carried out to bonding Cu and Ni substrates with Sn as interlayer.The element distribution and grain morpholog...A novel solid-liquid interdiffusion(SLID)bonding method with the assistance of temperature gradient(TG)was carried out to bonding Cu and Ni substrates with Sn as interlayer.The element distribution and grain morphology of interfacial intermetallic compound(IMC)in Cu/Sn/Ni micro-joints during both SLID and TG-SLID bonding and in the final Cu/(Cu,Ni)_(6)Sn_(5)/Ni full IMC micro-joints were analyzed.Under the effect of Cu-Ni cross-interaction,interfacial(Cu,Ni)_(6)Sn_(5) dominated the IMC growth at all the interfaces.The morphology of the(Cu,Ni)_(6)Sn_(5) grains was closely related to Ni content with three levels of low,medium and high.The full IMC micro-joints consisted of L-(Cu,Ni)_(6) Sn_(5),M-(Cu,Ni)_(6)Sn_(5) and H-(Cu,Ni)_(6)Sn_(5) grains after SLID bonding or TG-SLID bonding with Ni as hot end,while only L-(Cu,Ni)_(6)Sn_(5) grains after TG-SLID bonding with Cu as hot end,showing that the direction of TG had a remarkably effect on the growth and morphology of the interfacial(Cu,Ni)_(6)Sn_(5) during TG-SLID bonding.Thermodynamic analysis revealed the key molar latent heat and critical Ni content between fine-rounded-like(Cu,Ni)_(6)Sn_(5) and block-like(Cu,Ni)_(6)Sn_(5) were 17,725.4 J and 11.0 at.%at 260℃,respectively.Moreover,the growth kinetic of the interfacial IMC was analyzed in detail during bonding with and without TG.Under the combination of TG and Cu-Ni cross-interaction,void-free full IMC micro-joints were fast formed by TG-SLID bonding with Cu as hot end.This bonding method may present a feasible solution to solve the problems of low formation efficiency and inevitable Cu_(3) Sn growth of full IMC joints for 3 D packaging applications.展开更多
There have been many theoretical studies and numerical investigations of nonlocal diffusion(ND)problems in recent years.In this paper,we propose and analyze a new discontinuous Galerkin method for solving one-dimensio...There have been many theoretical studies and numerical investigations of nonlocal diffusion(ND)problems in recent years.In this paper,we propose and analyze a new discontinuous Galerkin method for solving one-dimensional steady-state and time-dependent ND problems,based on a formulation that directly penalizes the jumps across the element interfaces in the nonlocal sense.We show that the proposed discontinuous Galerkin scheme is stable and convergent.Moreover,the local limit of such DG scheme recovers classical DG scheme for the corresponding local diff usion problem,which is a distinct feature of the new formulation and assures the asymptotic compatibility of the discretization.Numerical tests are also presented to demonstrate the eff ectiveness and the robustness of the proposed method.展开更多
In this paper,we deal with some fast di usion equations ut=um+au vp and vt=△v^n+bu^qv^βsubject to null Dirichlet boundary conditions.We prove that every solution vanishes in nite time for pq>(m-α)(n-β),m>αa...In this paper,we deal with some fast di usion equations ut=um+au vp and vt=△v^n+bu^qv^βsubject to null Dirichlet boundary conditions.We prove that every solution vanishes in nite time for pq>(m-α)(n-β),m>αand n>β,where the exact relation of initial data is determined with the aid of some Sobolev Embedding inequalities.If pd<(m-α)(n-β),m>αand n>β,we show the barriers of the initial data which lead to the non-extinction of solutions.For the case pq=(m-α)(n-β),the solutions vanish for small initial data.The results fill in a gap for the case pq<mn in Nonlinear Anal.Real World Appl.4(2013)1931-1937.The coecients a and b play a vital role in the existence of non-extinction weak solution provided that a and b are large enough.At last,we use the scaling methods to determine some exponent regions where one of the components would blow up alone for some suitable initial data.展开更多
Objective To present the operative results of 17patients with atlantoaxial diseases using transoral approach.Methods17patients received operation of atlantoaxial fusion using transoral approach.The average age is 27ye...Objective To present the operative results of 17patients with atlantoaxial diseases using transoral approach.Methods17patients received operation of atlantoaxial fusion using transoral approach.The average age is 27years old(12～47years).Results All patients had achieved primary healing without any complications.The fusion rate was100%.The average recovery rate(JOAscore system)of myelopathy was48%.Conclusions Transoral approach was an ideal approach for upper cervical diseases.The infection rate could be lowered dow n to the minimum if the patients were properly managed perioperatively.Atlantoaxial fu sion could be achieved through this a pproach without instrumentation.展开更多
A diffusive predator-prey system with Holling-Tanner functional response and no-flux boundary condition is considered in this work.By using upper and lower solutions combined with iteration method,sufficient condition...A diffusive predator-prey system with Holling-Tanner functional response and no-flux boundary condition is considered in this work.By using upper and lower solutions combined with iteration method,sufficient condition which ensures the global asymptotical stability of the unique positive equilibrium of the system is obtained.It is shown that the prey refuge and the proportional harvesting can influence the global asymptotical stability of unique positive equilibrium of the system,furthermore,they can change the position of the unique interior equilibrium and make species coexist more easily.展开更多
基金pported by the National Natural Science Foundation of China(62265011 and 62122033)Jiangxi Provincial Natural Science Foundation(20224BAB212006 and 20232BAB 202038)National Key Research and Develop-ment Program of China(2023YFF1204302)。
文摘Acoustic-resolution photoacoustic microscopy(AR-PAM)suffers from degraded lateral resolution due to acoustic diffraction.Here,a resolution enhancement strategy for AR-PAM via a mean-reverting diffusion model was proposed to achieve the transition from acoustic resolution to optical resolution.By modeling the degradation process from high-resolution image to low-resolution AR-PAM image with stable Gaussian noise(i.e.,mean state),a mean-reverting diffusion model is trained to learn prior information of the data distribution.Then the learned prior is employed to generate a high-resolution image from the AR-PAM image by iteratively sampling the noisy state.The performance of the proposed method was validated utilizing the simulated and in vivo experimental data under varying lateral resolutions and noise levels.The results show that an over 3.6-fold enhancement in lateral resolution was achieved.The image quality can be effectively improved,with a notable enhancement of∼66%in PSNR and∼480%in SSIM for in vivo data.
基金Supported by China Postdoctoral Science Foundation(Grant No.2016M600015)National Natural Science Foundation of China(Grant Nos.51741601,51236006)
文摘Boundary layer suction is an e ective method used to delay separations in axial compressors. Most studies on bound?ary layer suction have focused on improving the performance of compressors,whereas few studies investigated the influence on details of the flow fields,especially vortexes in compressors. CFD method is validated with experi?mental data firstly. Three single?slot and one double?slot endwall boundary layer suction schemes are designed and investigated. In addition to the investigation of aerodynamic performance of the cascades with and without suction,variations in corner open separation,passage vortex,and concentration shedding vortex,which are rarely seen for the flow controlled blades in published literatures,are analyzed. Then,flow models,which are the ultimate aim,of both baseline and aspirated cascades are established. Results show that single?slot endwall suction scheme adjacent to the suction surface can e ectively remove the corner open separation. With suction mass flow rate of 0.85%,the overall loss coe cient and endwall loss coe cient of the cascade are reduced by 25.2% and 48.6%,respectively. Besides,this scheme increases the static pressure rise coe cient of the cascade by 3.2% and the flow turning angle of up to 3.3° at 90% span. The concentration shedding vortex decreases,whereas the passage vortex increases. For single?slot suction schemes near the middle pitchwise of the passage,the concentration shedding vortex increases and the passage vortex is divided into two smaller passage vortexes,which converge into a single?passage vortex near the trailing edge section of the cascade. For the double?slot suction scheme,triple?passage vortexes are presented in the blade passage. Some new vortex structures are discovered,and the novel flow models of aspirated compressor cascade are proposed,which are important to improve the design of multi?stage aspirated compressors.
基金financially supported by the National Natural Science Foundation of China(No.52075072)the Fundamental Research Funds for the Central Universities(No.DUT20JC46)。
文摘A novel solid-liquid interdiffusion(SLID)bonding method with the assistance of temperature gradient(TG)was carried out to bonding Cu and Ni substrates with Sn as interlayer.The element distribution and grain morphology of interfacial intermetallic compound(IMC)in Cu/Sn/Ni micro-joints during both SLID and TG-SLID bonding and in the final Cu/(Cu,Ni)_(6)Sn_(5)/Ni full IMC micro-joints were analyzed.Under the effect of Cu-Ni cross-interaction,interfacial(Cu,Ni)_(6)Sn_(5) dominated the IMC growth at all the interfaces.The morphology of the(Cu,Ni)_(6)Sn_(5) grains was closely related to Ni content with three levels of low,medium and high.The full IMC micro-joints consisted of L-(Cu,Ni)_(6) Sn_(5),M-(Cu,Ni)_(6)Sn_(5) and H-(Cu,Ni)_(6)Sn_(5) grains after SLID bonding or TG-SLID bonding with Ni as hot end,while only L-(Cu,Ni)_(6)Sn_(5) grains after TG-SLID bonding with Cu as hot end,showing that the direction of TG had a remarkably effect on the growth and morphology of the interfacial(Cu,Ni)_(6)Sn_(5) during TG-SLID bonding.Thermodynamic analysis revealed the key molar latent heat and critical Ni content between fine-rounded-like(Cu,Ni)_(6)Sn_(5) and block-like(Cu,Ni)_(6)Sn_(5) were 17,725.4 J and 11.0 at.%at 260℃,respectively.Moreover,the growth kinetic of the interfacial IMC was analyzed in detail during bonding with and without TG.Under the combination of TG and Cu-Ni cross-interaction,void-free full IMC micro-joints were fast formed by TG-SLID bonding with Cu as hot end.This bonding method may present a feasible solution to solve the problems of low formation efficiency and inevitable Cu_(3) Sn growth of full IMC joints for 3 D packaging applications.
基金Q.Du’s research is partially supported by US National Science Foundation Grant DMS-1719699,US AFOSR MURI Center for Material Failure Prediction Through Peridynamics,and US Army Research Office MURI Grant W911NF-15-1-0562.L.Ju’s research is partially supported by US National Science Foundation Grant DMS-1818438.J.Lu’s research is partially supported by Postdoctoral Science Foundation of China Grant 2017M610749.X.Tian’s research is partially supported by US National Science Foundation Grant DMS-1819233.
文摘There have been many theoretical studies and numerical investigations of nonlocal diffusion(ND)problems in recent years.In this paper,we propose and analyze a new discontinuous Galerkin method for solving one-dimensional steady-state and time-dependent ND problems,based on a formulation that directly penalizes the jumps across the element interfaces in the nonlocal sense.We show that the proposed discontinuous Galerkin scheme is stable and convergent.Moreover,the local limit of such DG scheme recovers classical DG scheme for the corresponding local diff usion problem,which is a distinct feature of the new formulation and assures the asymptotic compatibility of the discretization.Numerical tests are also presented to demonstrate the eff ectiveness and the robustness of the proposed method.
基金Supported by Shandong Provincial Natural Science Foundation of China。
文摘In this paper,we deal with some fast di usion equations ut=um+au vp and vt=△v^n+bu^qv^βsubject to null Dirichlet boundary conditions.We prove that every solution vanishes in nite time for pq>(m-α)(n-β),m>αand n>β,where the exact relation of initial data is determined with the aid of some Sobolev Embedding inequalities.If pd<(m-α)(n-β),m>αand n>β,we show the barriers of the initial data which lead to the non-extinction of solutions.For the case pq=(m-α)(n-β),the solutions vanish for small initial data.The results fill in a gap for the case pq<mn in Nonlinear Anal.Real World Appl.4(2013)1931-1937.The coecients a and b play a vital role in the existence of non-extinction weak solution provided that a and b are large enough.At last,we use the scaling methods to determine some exponent regions where one of the components would blow up alone for some suitable initial data.
文摘Objective To present the operative results of 17patients with atlantoaxial diseases using transoral approach.Methods17patients received operation of atlantoaxial fusion using transoral approach.The average age is 27years old(12～47years).Results All patients had achieved primary healing without any complications.The fusion rate was100%.The average recovery rate(JOAscore system)of myelopathy was48%.Conclusions Transoral approach was an ideal approach for upper cervical diseases.The infection rate could be lowered dow n to the minimum if the patients were properly managed perioperatively.Atlantoaxial fu sion could be achieved through this a pproach without instrumentation.
基金the foundation of Fujian Education Bureau(JT180041).
文摘A diffusive predator-prey system with Holling-Tanner functional response and no-flux boundary condition is considered in this work.By using upper and lower solutions combined with iteration method,sufficient condition which ensures the global asymptotical stability of the unique positive equilibrium of the system is obtained.It is shown that the prey refuge and the proportional harvesting can influence the global asymptotical stability of unique positive equilibrium of the system,furthermore,they can change the position of the unique interior equilibrium and make species coexist more easily.
