In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation pr...In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment.展开更多
In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperatur...In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.展开更多
BACKGROUND A 48-year-old female presented with sudden-onset right-sided aural fullness,low-frequency hearing loss,and tinnitus.Medical history included right-sided tempo-romandibular joint disorder(TMJD)with crepitati...BACKGROUND A 48-year-old female presented with sudden-onset right-sided aural fullness,low-frequency hearing loss,and tinnitus.Medical history included right-sided tempo-romandibular joint disorder(TMJD)with crepitation,and retro-orbital headaches.The patient was diagnosed with atypical Meniere’s disease(MD)and received in-tratympanic steroids,prednisone,betahistine,and began a low-sodium diet;how-ever,the patient’s symptoms worsened.CASE SUMMARY The patient sought physical therapy for TMJD;testing revealed reduced motion and dysfunction with vertical opening,lateral excursion of the mandible to the right,and tenderness to palpation.Treatment included soft tissue mobilization of right facial structures and temporal fossa,intraoral massage of the right pterygoid musculature,and massage of right neck structures.After 4 weeks,the patient noticed subjective improvement in hearing and decreased headaches.After 11 weeks,an audiogram showed that the hearing loss had recovered.The patient has continued the daily at-home intraoral/neck massage therapy and maintained normal hearing over 4 years to date.The temporal relationship between physical therapy and recovery of hearing loss suggests muscular or inflammatory etiology as at least partially causative of this patient’s symptoms.The mechanism of healing may have been due to decreased inflammation,improved blood flow,restored function of cranial nerves,or some combination of these and other unknown factors.CONCLUSION This report suggests that orofacial physical and massage therapy may be an effective treatment for the cochlear symptoms associated with MD.展开更多
Preservation of low-frequency residual hearing is very important for combined electro-acoustic stimulation after cochlear implantation.However,in clinical practice,loss of low-frequency residual hearing often occurs a...Preservation of low-frequency residual hearing is very important for combined electro-acoustic stimulation after cochlear implantation.However,in clinical practice,loss of low-frequency residual hearing often occurs after cochlear implantation and its mechanisms remain unclear.Factors affecting lowfrequency residual hearing after cochlear implantation are one of the hot spots in current research.Inflammation induced by injury associated with cochlear implantation is deemed to be significant,as it may give rise to low-frequency residual hearing loss by interfering with the blood labyrinth barrier and neural synapses.Pathological changes along the pathway for low-frequency auditory signals transmission may include latent factors such as damage to neuroepithelial structures,synapses,stria vascularis and other ultrastructures.In this review,current research on mechanisms of low-frequency residual hearing loss after cochlear implantation and possible roles of inflammatory responses are summarized.展开更多
基金National Natural Science Foundation of China(Grant Nos.51821003,52175524,61704158)the Natural Science Foundation of Shanxi Province(Grant No.202103021224206)Shanxi"1331 Project"Key Subjects Construction to provide fund for conducting experiments。
文摘In order to suppress the low-frequency ultrasound vibration in the broadband range of 20 k Hz—100 k Hz,this paper proposes and discusses an acoustic metamaterial with low-frequency ultrasound vibration attenuation properties,which is configured by hybrid arc and sharp-angle convergent star-shaped lattices.The effect of the dispersion relation and the bandgap characteristic for the scatterers in star-shaped are simulated and analyzed.The target bandgap width is extended by optimizing the geometry parameters of arc and sharp-angle convergent lattices.The proposed metamaterial configured by optimized hybrid lattices exhibits remarkable broad bandgap characteristics by bandgap complementarity,and the simulation results verify a 99%vibration attenuation amplitude can be obtained in the frequency of20 k Hz—100 k Hz.After the fabrication of the proposed hybrid configurational star-shaped metamaterial by 3D printing technique,the transmission loss experiments are performed,and the experimental results indicate that the fabricated metamaterial has the characteristics of broadband vibration attenuation and an amplitude greater than 85%attenuation for the target frequency.These results demonstrate that the hybrid configurational star-shaped metamaterials can effectively widen the bandgap and realize high efficiency attenuation,which has capability for the vibration attenuation in the application of highprecise equipment.
基金supported by the National Natural Science Foundation of China(No.62271109)。
文摘In this paper,a control scheme based on current optimization is proposed for dual three-phase permanent-magnet synchronous motor(DTP-PMSM)drive to reduce the low-frequency temperature swing.The reduction of temperature swing can be equivalent to reducing maximum instantaneous phase copper loss in this paper.First,a two-level optimization aiming at minimizing maximum instantaneous phase copper loss at each electrical angle is proposed.Then,the optimization is transformed to a singlelevel optimization by introducing the auxiliary variable for easy solving.Considering that singleobjective optimization trades a great total copper loss for a small reduction of maximum phase copper loss,the optimization considering both instantaneous total copper loss and maximum phase copper loss is proposed,which has the same performance of temperature swing reduction but with lower total loss.In this way,the proposed control scheme can reduce maximum junction temperature by 11%.Both simulation and experimental results are presented to prove the effectiveness and superiority of the proposed control scheme for low-frequency temperature swing reduction.
文摘BACKGROUND A 48-year-old female presented with sudden-onset right-sided aural fullness,low-frequency hearing loss,and tinnitus.Medical history included right-sided tempo-romandibular joint disorder(TMJD)with crepitation,and retro-orbital headaches.The patient was diagnosed with atypical Meniere’s disease(MD)and received in-tratympanic steroids,prednisone,betahistine,and began a low-sodium diet;how-ever,the patient’s symptoms worsened.CASE SUMMARY The patient sought physical therapy for TMJD;testing revealed reduced motion and dysfunction with vertical opening,lateral excursion of the mandible to the right,and tenderness to palpation.Treatment included soft tissue mobilization of right facial structures and temporal fossa,intraoral massage of the right pterygoid musculature,and massage of right neck structures.After 4 weeks,the patient noticed subjective improvement in hearing and decreased headaches.After 11 weeks,an audiogram showed that the hearing loss had recovered.The patient has continued the daily at-home intraoral/neck massage therapy and maintained normal hearing over 4 years to date.The temporal relationship between physical therapy and recovery of hearing loss suggests muscular or inflammatory etiology as at least partially causative of this patient’s symptoms.The mechanism of healing may have been due to decreased inflammation,improved blood flow,restored function of cranial nerves,or some combination of these and other unknown factors.CONCLUSION This report suggests that orofacial physical and massage therapy may be an effective treatment for the cochlear symptoms associated with MD.
文摘Preservation of low-frequency residual hearing is very important for combined electro-acoustic stimulation after cochlear implantation.However,in clinical practice,loss of low-frequency residual hearing often occurs after cochlear implantation and its mechanisms remain unclear.Factors affecting lowfrequency residual hearing after cochlear implantation are one of the hot spots in current research.Inflammation induced by injury associated with cochlear implantation is deemed to be significant,as it may give rise to low-frequency residual hearing loss by interfering with the blood labyrinth barrier and neural synapses.Pathological changes along the pathway for low-frequency auditory signals transmission may include latent factors such as damage to neuroepithelial structures,synapses,stria vascularis and other ultrastructures.In this review,current research on mechanisms of low-frequency residual hearing loss after cochlear implantation and possible roles of inflammatory responses are summarized.
