A novel rectangular microstrip antenna on conventional dielectric substrate with centrally loaded inductive septums are proposed for dual band operation. The proposed antenna has been thoroughly investigated and the r...A novel rectangular microstrip antenna on conventional dielectric substrate with centrally loaded inductive septums are proposed for dual band operation. The proposed antenna has been thoroughly investigated and the results are presented in the paper. The conventional patch antenna fabricated on common substrates always resonates at its dominant TM10 mode which produces the radiation field along its broadside direction. In the present investigation, the same microstrip antenna is designed on conventional substrate with centrally located inductive septums beneath the patch, with a view to develop a new resonant mode which will produce radiation like dominant TM10 mode. The speciality of the proposed antenna is to excite a new resonant mode with good impedance bandwidth while the traditional dominant TM10 mode is kept unaltered. A thorough quantitative analysis is presented to justify the reason of generation of new resonant mode along with the traditional dominant TM10 mode. An easy and handful formulation has been established for calculation of the frequency for new resonant mode as a function of antenna parameters and the gap between the septums. The proposed idea has been verified through a commercial software package for a patch operating in C band and an excellent agreement is revealed.展开更多
Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF...Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF septum liner and its impedance model on the Beihang Grazing Flow Duct(BGFD)setup,over a wide frequency range under grazing flows up to 0.5 Mach number and Sound Pressure Level(SPL)up to 150 dB,typically encountered in aeroengine nacelles.Several specimens varying in the numbers,types,and depths of septa among units are designed,fabricated,and measured.Their impedances and Transmission Losses(TL)are obtained using the mirror-based multimodal straightforward method and the mode decomposition technique,respectively.Generally,the model predictions show good agreement with the educed impedances in all cases,and such liners with a large-porosity facesheet exhibit low acoustic nonlinearities in the presence of high SPL,especially under high-velocity grazing flows.Moreover,a MDOF liner we delicately designed,compared with a conventional broadband three-layer perforated liner as the reference,is close to the resonant state at more frequencies and thus has higher and wider measured TL spectra almost from 1 kHz up to 10 kHz at studied Mach numbers,under the premise of saving 22.7 mm in the thickness.These show that,the MDOF septum liner,if well designed,can achieve an ultra-broadband efficient sound attenuation using more limited spaces in complex aeroacoustic environments.展开更多
Fear memory is crucial for survival and adaptation in complex and dynamically changing environments that enables individuals to avoid or escape from potentially dangerous situations.However,excessive fear memories can...Fear memory is crucial for survival and adaptation in complex and dynamically changing environments that enables individuals to avoid or escape from potentially dangerous situations.However,excessive fear memories can significantly contribute to emotional disabilities and mental disorders,including panic disorder,phobias,social anxiety disorder,and post-traumatic stress disorder(PTSD).展开更多
BACKGROUNDA mid-esophageal diverticulum is an outpouching located in the midsection ofthe esophagus, posterior to the bifurcation of the right and left bronchi. The conditionis characterized by an outward protrusion o...BACKGROUNDA mid-esophageal diverticulum is an outpouching located in the midsection ofthe esophagus, posterior to the bifurcation of the right and left bronchi. The conditionis characterized by an outward protrusion of the inner esophageal wall. Midesophagealdiverticula are relatively rare and may coexist with diffuse esophagealspasm. However, the potential esophageal motility disorders associated withthese lesions are frequently overlooked in clinical practice. The use of endoscopicinterventions may offer a novel approach for the alleviation of dysphagia associatedwith this condition.CASE SUMMARYWe present a case of a 74-year-old woman with dysphagia, diagnosed with midesophagealdiverticulum and diffuse esophageal spasm. Due to her physical condition,submucosal tunneling endoscopic septum division (STESD) was initiallyperformed for the diverticulum. One month later, the esophageal spasm wastreated using per-oral endoscopic myotomy (POEM). This combined treatmentsignificantly improved her dysphagia, and she was discharged.CONCLUSIONSTESD and POEM are effective and safe for the treatment of dysphagia caused bymid-esophageal diverticula with diffuse esophageal spasm.展开更多
文摘A novel rectangular microstrip antenna on conventional dielectric substrate with centrally loaded inductive septums are proposed for dual band operation. The proposed antenna has been thoroughly investigated and the results are presented in the paper. The conventional patch antenna fabricated on common substrates always resonates at its dominant TM10 mode which produces the radiation field along its broadside direction. In the present investigation, the same microstrip antenna is designed on conventional substrate with centrally located inductive septums beneath the patch, with a view to develop a new resonant mode which will produce radiation like dominant TM10 mode. The speciality of the proposed antenna is to excite a new resonant mode with good impedance bandwidth while the traditional dominant TM10 mode is kept unaltered. A thorough quantitative analysis is presented to justify the reason of generation of new resonant mode along with the traditional dominant TM10 mode. An easy and handful formulation has been established for calculation of the frequency for new resonant mode as a function of antenna parameters and the gap between the septums. The proposed idea has been verified through a commercial software package for a patch operating in C band and an excellent agreement is revealed.
基金co-supported by the National Natural Science Foundation of China(No.52206039)the Taihang Laboratory of China(No.A2053)+1 种基金the Aeronautical Science Foundation of China(No.20240011051001)the National Key R&D Program of China(No.2021YFB3703900)。
文摘Developing advanced acoustic treatments,such as the Multi-Degree-of-Freedom(MDOF)septum liner,to realize the broadband noise reduction is critical for silent aeroengines.This study investigates experimentally the MDOF septum liner and its impedance model on the Beihang Grazing Flow Duct(BGFD)setup,over a wide frequency range under grazing flows up to 0.5 Mach number and Sound Pressure Level(SPL)up to 150 dB,typically encountered in aeroengine nacelles.Several specimens varying in the numbers,types,and depths of septa among units are designed,fabricated,and measured.Their impedances and Transmission Losses(TL)are obtained using the mirror-based multimodal straightforward method and the mode decomposition technique,respectively.Generally,the model predictions show good agreement with the educed impedances in all cases,and such liners with a large-porosity facesheet exhibit low acoustic nonlinearities in the presence of high SPL,especially under high-velocity grazing flows.Moreover,a MDOF liner we delicately designed,compared with a conventional broadband three-layer perforated liner as the reference,is close to the resonant state at more frequencies and thus has higher and wider measured TL spectra almost from 1 kHz up to 10 kHz at studied Mach numbers,under the premise of saving 22.7 mm in the thickness.These show that,the MDOF septum liner,if well designed,can achieve an ultra-broadband efficient sound attenuation using more limited spaces in complex aeroacoustic environments.
文摘Fear memory is crucial for survival and adaptation in complex and dynamically changing environments that enables individuals to avoid or escape from potentially dangerous situations.However,excessive fear memories can significantly contribute to emotional disabilities and mental disorders,including panic disorder,phobias,social anxiety disorder,and post-traumatic stress disorder(PTSD).
基金Supported by Natural Science Foundation of Shandong Province,No.81700472Clinical+X Project Fund of Binzhou Medical College,No.BY2021LCX11and Binzhou Medical University Science and Technology Program Projects,No.BY2019KJ13.
文摘BACKGROUNDA mid-esophageal diverticulum is an outpouching located in the midsection ofthe esophagus, posterior to the bifurcation of the right and left bronchi. The conditionis characterized by an outward protrusion of the inner esophageal wall. Midesophagealdiverticula are relatively rare and may coexist with diffuse esophagealspasm. However, the potential esophageal motility disorders associated withthese lesions are frequently overlooked in clinical practice. The use of endoscopicinterventions may offer a novel approach for the alleviation of dysphagia associatedwith this condition.CASE SUMMARYWe present a case of a 74-year-old woman with dysphagia, diagnosed with midesophagealdiverticulum and diffuse esophageal spasm. Due to her physical condition,submucosal tunneling endoscopic septum division (STESD) was initiallyperformed for the diverticulum. One month later, the esophageal spasm wastreated using per-oral endoscopic myotomy (POEM). This combined treatmentsignificantly improved her dysphagia, and she was discharged.CONCLUSIONSTESD and POEM are effective and safe for the treatment of dysphagia caused bymid-esophageal diverticula with diffuse esophageal spasm.
