Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological signal.The paper presents an analytical approac...Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological signal.The paper presents an analytical approach to study interfacial mechanics of the 2D planar EEDs on the checkerboard buckling patterns of human skin.Energy variation method is proposed to determine a criterion whether EEDs laminate conformally onto the skin surface under undeformed and stretched cases.EEDs with low bending stiffness(thin,soft devices/backing layer),smooth and soft skin,and strong adhesion promote conformal contact.Furthermore,the adhesion energy at the EED/skin interface is measured by the homemade peeling experiment platform with different substrate thicknesses and areal coverages.The upper limit of the areal coverage for EED conformal contact with the skin is proposed with given EED/skin properties.Conformability of EEDs are validated by experiments with different substrate thickness,areal coverage and external loadings.It provides a design guideline for EED to conformally contact with the skin surface for more accurate biological signal monitoring.展开更多
There is an urgent need for the application of broadband Microwave Absorption(MA)structures on the leading edges of aircraft wings,which requires the MA structures to possess both the broadband MA performance and grea...There is an urgent need for the application of broadband Microwave Absorption(MA)structures on the leading edges of aircraft wings,which requires the MA structures to possess both the broadband MA performance and great surface conformability.To meet these requirements,we designed and fabricated a flexible bioinspired meta-structure with ultra-broadband MA,thin thickness and excellent surface conformality.The carbonyl iron powder-carbon nanotubes-polydimethylsiloxane composite was synthesized by physical blending method for fabricating the MA meta-structure.Through geometry-electromagnetic optimal design by heuristic optimization algorithm,the meta-structure mimicking to the nipple photonic nanostructures on the eyes of moth can achieve ultra-broadband MA performance of 35.14 GHz MA bandwidth(reflection loss≤–10 dB),covering 4.86–40.00 GHz,with thickness of only 4.3 mm.Through simple fabrication processes,the meta-structure has been successfully fabricated and bonded on wings’leading edges,exhibiting excellent surface conformability.Furthermore,the designed flexible MA meta-structure possesses significant Radar Cross-Section(RCS)reduction capability,as demonstrated by the RCS analysis of an unmanned aerial vehicle.This flexible ultra-broadband MA meta-structure provides an outstanding candidate to meet the radar stealth requirement of variable curvature structures on aircraft.展开更多
针对单通道语音增强中主流编解码结构面临的声学特征提取不充分、通道信息丢失和幅度相位补偿困难等问题,提出一种融合不同维度语音特征的异构双分支解码单通道语音增强模型——HDBMV(Heterogeneous DualBranch with Multi-View)。该模...针对单通道语音增强中主流编解码结构面临的声学特征提取不充分、通道信息丢失和幅度相位补偿困难等问题,提出一种融合不同维度语音特征的异构双分支解码单通道语音增强模型——HDBMV(Heterogeneous DualBranch with Multi-View)。该模型通过信息融合编码器(IFE)、时频残差Conformer(TFRC)模块、多视角注意力(MVA)模块和异构双分支解码器(HDBD)等机制,提升单通道语音增强的性能。首先,IFE联合处理振幅与复数特征,捕捉全局依赖和局部相关,生成紧凑的特征表示;其次,TFRC模块有效捕捉时间维度和频域维度上的相关性,同时降低计算复杂度;再次,MVA模块重构通道域和时频域信息,进一步增强模型对信息的多视角多层次的表征能力;最后,HDBD分别处理幅度特征和细化复数特征,解决幅度相位补偿问题,提升解码鲁棒性。实验结果表明,HDBMV在公开数据集VoiceBank+DEMAND、大数据集DNS Challenge 2020和自建的藏语数据集BodSpeDB上的语音质量感知评估(PESQ)分别达到了3.00、3.12和2.09,短时目标可理解度(STOI)分别达到了0.96、0.97和0.81。可见,HDBMV以最小的参数量和较高的计算效率获得了最佳的语音增强性能和较强的泛化能力。展开更多
To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method...To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method for a class of parallel platforms with 3-RE structure after locking the actuated joints is proposed in this paper.Given that the angle between specific joint axes of limbs remains constant,a set of geometric constraints for the forward kinematics of parallel mechanisms(PM)are determined.After translating unit direction vectors of these joint axes to the common starting point,the geometric constraints of the angle between the vectors are transformed into the distances between the endpoints of the vectors,making them easier to handle.Under the framework of CGA,the positions of key points that determine the position and orientation of the moving platform can be intuitively determined by the intersection,division,and duality of basic geometric entities.By employing the tangent half-angle substitution,the forward kinematic analysis of the parallel mechanisms leads to a high-order univariate polynomial equation without the need for any complex algebraic elimination operations.After solving this equation and back substitution,the position and pose of the MP can be obtained indirectly.A numerical case is utilized to confirm the effectiveness of the proposed method.展开更多
文摘Smoothly attaching the stretchable epidermal electronic devices(EEDs) onto the skin surface is highly desired to improve the measurement accuracy of electrophysiological signal.The paper presents an analytical approach to study interfacial mechanics of the 2D planar EEDs on the checkerboard buckling patterns of human skin.Energy variation method is proposed to determine a criterion whether EEDs laminate conformally onto the skin surface under undeformed and stretched cases.EEDs with low bending stiffness(thin,soft devices/backing layer),smooth and soft skin,and strong adhesion promote conformal contact.Furthermore,the adhesion energy at the EED/skin interface is measured by the homemade peeling experiment platform with different substrate thicknesses and areal coverages.The upper limit of the areal coverage for EED conformal contact with the skin is proposed with given EED/skin properties.Conformability of EEDs are validated by experiments with different substrate thickness,areal coverage and external loadings.It provides a design guideline for EED to conformally contact with the skin surface for more accurate biological signal monitoring.
基金supported by the Basic Research Development Program of China(No.JCKY2021607B036)the National Natural Science Foundation of China(No.52275512).
文摘There is an urgent need for the application of broadband Microwave Absorption(MA)structures on the leading edges of aircraft wings,which requires the MA structures to possess both the broadband MA performance and great surface conformability.To meet these requirements,we designed and fabricated a flexible bioinspired meta-structure with ultra-broadband MA,thin thickness and excellent surface conformality.The carbonyl iron powder-carbon nanotubes-polydimethylsiloxane composite was synthesized by physical blending method for fabricating the MA meta-structure.Through geometry-electromagnetic optimal design by heuristic optimization algorithm,the meta-structure mimicking to the nipple photonic nanostructures on the eyes of moth can achieve ultra-broadband MA performance of 35.14 GHz MA bandwidth(reflection loss≤–10 dB),covering 4.86–40.00 GHz,with thickness of only 4.3 mm.Through simple fabrication processes,the meta-structure has been successfully fabricated and bonded on wings’leading edges,exhibiting excellent surface conformability.Furthermore,the designed flexible MA meta-structure possesses significant Radar Cross-Section(RCS)reduction capability,as demonstrated by the RCS analysis of an unmanned aerial vehicle.This flexible ultra-broadband MA meta-structure provides an outstanding candidate to meet the radar stealth requirement of variable curvature structures on aircraft.
基金Supported by National Natural Science Foundation of China (Grant No. 52175019)Beijing Municipal Natural Science Foundation of China (Grant No. L222038)+3 种基金Beijing Nova Programme Interdisciplinary Cooperation Project of China (Grant No. 20240484699)Joint Funds of Industry-University-Research of Shanghai Academy of Spaceflight Technology of China (Grant No. SAST2022-017)Beijing Municipal Key Laboratory of Space-ground Interconnection and Convergence of ChinaKey Laboratory of IoT Monitoring and Early Warning,Ministry of Emergency Management of China
文摘To investigate the forward kinematics problem of parallel mechanisms with complex limbs and to expand the applicability of the powerful tool of Conformal Geometric Algebra(CGA),a CGA-based modeling and solution method for a class of parallel platforms with 3-RE structure after locking the actuated joints is proposed in this paper.Given that the angle between specific joint axes of limbs remains constant,a set of geometric constraints for the forward kinematics of parallel mechanisms(PM)are determined.After translating unit direction vectors of these joint axes to the common starting point,the geometric constraints of the angle between the vectors are transformed into the distances between the endpoints of the vectors,making them easier to handle.Under the framework of CGA,the positions of key points that determine the position and orientation of the moving platform can be intuitively determined by the intersection,division,and duality of basic geometric entities.By employing the tangent half-angle substitution,the forward kinematic analysis of the parallel mechanisms leads to a high-order univariate polynomial equation without the need for any complex algebraic elimination operations.After solving this equation and back substitution,the position and pose of the MP can be obtained indirectly.A numerical case is utilized to confirm the effectiveness of the proposed method.
