A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter.The structure is a new method of connecting microstrip circuits and waveguide filters,a...A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter.The structure is a new method of connecting microstrip circuits and waveguide filters,and this new structure enables a planar integrated transition from microstrip lines to ultra-thin cavity filters,thereby reducing the size of the transition structure and achieving miniaturization.The structure includes a conventional tapered microstrip transition structure,which guides the electromagnetic field from the microstrip line to the reduced-height dielectric-filled waveguide,and an air-filled matching cavity which is placed between the dielectric-filled waveguide and the ultra-thin cavity filter.The heights of the microstrip line,the dielectric-filled waveguide and the ultra-thin cavity filter are the same,enabling seamless integration within a planar radio-frequency(RF)circuit.To facilitate testing,mature finline transition structures are integrated at both ends of the microstrip line during fabrications.The simulation results of the fabricated microstrip to ultra-thin cavity filter transition with the finline transition structure,with a passband of 91.5-96.5 GHz,has an insertion loss of less than 1.9 dB and a return loss lower than-20 dB.And the whole structure has also been measured which achieves an insertion loss less than 2.6 dB and a return loss lower than-15 dB within the filter's passband,including the additional insertion loss introduced by the finline transitions.Finally,a W-band compact up-conversion module is designed,and the test results show that after using the proposed structure,the module achieves 95 dBc suppression of the 84 GHz local oscillator.It is also demonstrated that the structure proposed in this letter achieves miniaturization of the system integration without compromising the filter performance.展开更多
To address the challenges associated with multi-sided shells in traditional isogeometric analysis(IGA),this paper introduces a novel isogeometric shell method for trimmed CAD geometries based on toric surfaces and Rei...To address the challenges associated with multi-sided shells in traditional isogeometric analysis(IGA),this paper introduces a novel isogeometric shell method for trimmed CAD geometries based on toric surfaces and Reissner–Mindlin shell theory.By utilizing toric surface patches,both trimmed and untrimmed elements of the CAD surfaces are represented through a unified geometric framework,ensuring continuity and an accurate geometric description.Toric-Bernstein basis functions are employed to accurately interpolate the geometry and displacement of the trimmed shell.For singularities and corner points on the toric surface,the normal vector is defined as the unit directional vector from the center of curvature to the corresponding control point.Several numerical examples of polygonal shells are presented to evaluate the effectiveness and robustness of the proposed method.This approach significantly simplifies the treatment of trimmed shell IGA and provides a promising solution for simulating complex shell structures with intricate boundaries.展开更多
Modulating the dipole polarization loss in the single-atom region and establishing its direct relationship with the electromagnetic wave absorption(EWA)performance remain an unmet challenge.Here,a dual-ligand modulati...Modulating the dipole polarization loss in the single-atom region and establishing its direct relationship with the electromagnetic wave absorption(EWA)performance remain an unmet challenge.Here,a dual-ligand modulation strategy,i.e.,partially changing coordination atoms in the single-metal region(sMr),is introduced to effectively break the coordination symmetry of conjugated metal-organic frameworks(cMOFs),finally enhancing EWA property of cMOFs materials.Further,the asymmetrical sMr is experimentally found to elicit the dipole polarization loss,overcoming the handicaps of other electromagnetic wave loss mechanisms,which directly contribution to enhance EWA performance of this series of cMOFs.This strategy is further confirmed by replacing metal centers.Among studied series of cMOFs,Cu_(2.25)/Co_(0.75)(HHTP1.67HITP0.33)achieves excellent EWA performance with an effective absorption bandwidth of 5.00 GHz and a reflection loss of66.03 dB.We introduce a dual-ligand modulation strategy targeting single-metal regions within cMOFs here,aiming to achieve superior EWA performance through atomic-scale dipole polarization loss modulation.We hope our study can inspire more exploration to realize high-performance EWA materials.展开更多
The aerodynamics of gas-particle suspensions is simulated as an Euler-Euler two-fluid model in a revolving rotor over a particle bed. The interactions of collisions between the blade and particles and particle-particl...The aerodynamics of gas-particle suspensions is simulated as an Euler-Euler two-fluid model in a revolving rotor over a particle bed. The interactions of collisions between the blade and particles and particle-particle interactions are modeled using the kinetic theory of granular flow(KTGF). The gas turbulence induced by the rotation of the rotor is modeled using the kg-εg model. The flow field of a revolving rotor is simulated using the multiple reference frame(MRF) method. The distributions of velocities, volume fractions, and gas pressure are predicted while the aircraft hovers at different altitudes.The gas pressure decreases from the hub to the tip of the blade, and it is higher at the pressure side than that at the suction side of the rotor. The turbulent kinetic energy of the gas increases toward the blade tip. The volume fraction of particles decreases as the hovering altitude increases. The simulated pressure coefficient is compared with that in experimental measurements.展开更多
Transition metal oxides are ideal electrode materials used for supercapacitors.However,the synthesis of transition metal oxides suffers from drawbacks such as high reaction temperature and energy consumption.Herein,we...Transition metal oxides are ideal electrode materials used for supercapacitors.However,the synthesis of transition metal oxides suffers from drawbacks such as high reaction temperature and energy consumption.Herein,we report the synthesis of sea urchin-like Co3 O4-NiO composites supported on graphene oxide(GO) using a hydrothermal method followed by calcination with a low temperature(250℃).The obtained Co3O4-NiO/GO composite demonstrates a high specific capacitance of 883 F g^-1 at 1 A g^-1.Furthermore,upon coupling with an activated carbon(AC) positive electrode,an asymmetric cell of Co3 O4-NiO/GO//AC exhibits outstanding stability reflected by the high capacitance retention of 82% at a high current density of 10 A g^-1.The excellent electrochemical properties of the composite may be attributed to the good synergistic effect of Co3O4 and NiO,as well as the assembly of Co3 O4 and NiO into a sea urchin structure,which results in increased electron conductivity and more exposed electroactive sites leading to the promotion of the Faradaic redox process.展开更多
To alleviate the localization error introduced by irregular sensor network deployment, a new mo bile path localization based on key nodes （MPLPK） protocol is proposed. It can recognize all con cave/convex nodes in t...To alleviate the localization error introduced by irregular sensor network deployment, a new mo bile path localization based on key nodes （MPLPK） protocol is proposed. It can recognize all con cave/convex nodes in the network as fixed anchor nodes, and simplify the following localization process based on these key nodes. The MPLPK protocol is composed of three steps. After all key nodes are found in the network, a mobile node applying improved minimum spanning tree （MST） algorithm is introduced to traverse and locate them. By taking the concave/convex nodes as anchors, the complexity of the irregular network can be degraded. And the simulation results demonstrate that MPEPK has 20% to 40% accuracy improvements than connectivity-based and anchor-free three-di- mensional localization （CATL） and approximate convex decomposition based localization （ACDL）.展开更多
The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated by temperature-dependent current-voltage （T-I-V） measurements from 300 K to 473 K. The ideality factor and ...The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated by temperature-dependent current-voltage （T-I-V） measurements from 300 K to 473 K. The ideality factor and barrier height determined based on the thermionic emission （TE） theory are found to be strong functions of temperature, while present a great deviation from the theoretical value, which can be expounded by the barrier height inhomogeneities. In order to determine the forward current transport mechanisms, the experimental data are analyzed using numerical fitting method, considering the temperature-dependent series resistance. It is observed that the current flow at room temperature can be attributed to the tunneling mechanism, while thermionic emission current gains a growing proportion with an increase in temperature. Finally, the effective barrier height is derived based on the extracted thermionic emission component, and an evaluation of the density of dislocations is made from the I-V characteristics, giving a value of 1.49 × 10^7 cm^-2.展开更多
Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of wh...Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field(ExMF). Two types of Ex MFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet(PM) and another generated by an electromagnet(EM) on the order of 2 T. Two forces, including the magnetostatic force between the Ex MF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition,Ex MFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for a LFV device to operate normally under a moderate Ex MF. However, the magnetostatic force will account for a high proportion of the measured force,thus inhibiting the normal LFV operation, if the Ex MF is too high.展开更多
With science and technology development,vibration testing as the most important item in reliability test is becoming more and more important,at the same time,vibrate condition becoming more and more complicated,the ph...With science and technology development,vibration testing as the most important item in reliability test is becoming more and more important,at the same time,vibrate condition becoming more and more complicated,the phenomenon increases that the output of controller goes beyond controlling range so that destroy the specimen. In this paper,some skills such as how to set the parameters of force controller,where to place the sensor,which material to be chosen and which skills to be used while making jigs were introduced to avoid the just matter. At last,some examples were given to prove the validity of the method proposed.展开更多
As the process of economic globalization deepens,a large variety of integrated circuit designers tends to move the chip's manufacturing to the developing country.But during the globalization of semiconductor desig...As the process of economic globalization deepens,a large variety of integrated circuit designers tends to move the chip's manufacturing to the developing country.But during the globalization of semiconductor design and fabrication process,integrated circuits are suffering from increasing malicious alterations from the untrusted foundries,which pose a serious threat to the military,finance,transportation and other critical systems.An noninvasive approach was presented to measure the physical "sidechannel"parameter of a chip such as current or delay,which is effectively capable of detecting the malicious hardware alternations.The intrinsic relationship of a circuit's side-channel parameters was exploited to distinguish the effect of a Trojan in the presence of large random noise and process noise,such as the Dynamic current(IDDT)versus the maximum operating frequency(Fmax)correlation.The Monte Carlo analysis in Hspice using ± 20% Gauss variations in transistor threshold voltage(Vth)was carried out to simulate the circuit state in the real world.Simulation Results show that this approach is effective to detect the ultra-small Trojans.展开更多
High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather.Moreover,transversely galloping will be excited due to the irregular structure resulting from the alterna...High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather.Moreover,transversely galloping will be excited due to the irregular structure resulting from the alternation of lift force and drag force.In this paper,the nonlinear dynamics and internal resonance of an iced cable under wind excitation are investigated.Considering the excitation caused by pulsed wind and the movement of the support,the nonlinear governing equations of motion of the iced cable are established using a three-degree-of-freedom model based on Hamilton's principle.By the Galerkin method,the partial differential equations are then discretized into ordinary differential equations.The method of multiple scales is then used to obtain the averaged equations of the iced cable,and the principal parametric resonance-1/2 subharmonic resonance and the 2:1 internal resonance are considered.The numerical simulations are performed to investigate the dynamic response of the iced cable.It is found that there exist periodic,multi-periodic,and chaotic motions of the iced cable subjected to wind excitation.展开更多
Signature,widely used in cloud environment,describes the work as readily identifying its creator.The existing signature schemes in the literature mostly rely on the Hardness assumption which can be easily solved by qu...Signature,widely used in cloud environment,describes the work as readily identifying its creator.The existing signature schemes in the literature mostly rely on the Hardness assumption which can be easily solved by quantum algorithm.In this paper,we proposed an advanced quantum-resistant signature scheme for Cloud based on Eisenstein Ring(ETRUS)which ensures our signature scheme proceed in a lattice with higher density.We proved that ETRUS highly improve the performance of traditional lattice signature schemes.Moreover,the Norm of polynomials decreases significantly in ETRUS which can effectively reduce the amount of polynomials convolution calculation.Furthermore,storage complexity of ETRUS is smaller than classical ones.Finally,according to all convolution of ETRUS enjoy lower degree polynomials,our scheme appropriately accelerate 56.37%speed without reducing its security level.展开更多
The wide application of electromagnetic technology has led to increasingly frequent information transmission and communication interconnection.When the intensity of the disordered radiation of electromagnetic waves is...The wide application of electromagnetic technology has led to increasingly frequent information transmission and communication interconnection.When the intensity of the disordered radiation of electromagnetic waves is too high,it will cause electromagnetic pollution and pose a huge threat to human health or the survival of other animals and plants.How to ingeniously design absorbing materials is the key to solving the problem.This paper proposes a new design concept.The Co-based zeolite imidazolite-structured material ZIF-67 was selected as the main body of the metal-organic frameworks(MOFs)template,and the dodecahedral structured ZIF-67 nanoparticles were prepared using the classic ion-ligand process.Subsequently,a dodecahedral NiCo-LDH nanoparticle precursor composed of NiCo bimetallic hydroxide nanosheets with hollow edges and interior was obtained based on the liquid-phase cationic etching process.On this basis,thioacetamide(TAA)was selected as the vulcanizing agent,and the ZIF-67-derived sulfide inheriting the micro-nano structure of the precursor was obtained through liquid-phase hydrothermal vulcanization.The vulcanization growth mechanism and electromagnetic wave absorption mechanism of the MOF_(S)-derived sulfide were deeply explored.展开更多
Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell n...Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell nanobelt photodetector with a rise time of 11 /.is, which is the fastest among CdS based photodetectors reported previously. The improved response speed is ascribed to the sup-pressed possibilities of surface reaction resulting from the core-shell structure and heterojunction among the CdS, CdSxTel-x and CdTe. The measured response spectrum of CdS-CdSxTe1-x-CdTe core-shell nano-belt photodetector covers a wide range from 355 to 785 nm. Moreover, high responsivity （1,520 A/W） and large 3 dB bandwidth （~22.9 kHz） are obtained along with the fast response, The high performance in responsivity, sensitivity, spectral response and photoresponse speed makes this device a promising candidate for practical application in optical sensing, communication and imaging.展开更多
We propose a domain decomposition method based on the spectral element method(DDM-SEM)for elastic wave computation in frequency domain.It combines the high accuracy of the spectral element method and the high degree o...We propose a domain decomposition method based on the spectral element method(DDM-SEM)for elastic wave computation in frequency domain.It combines the high accuracy of the spectral element method and the high degree of parallelism of a domain decomposition technique,which makes this method suitable for accurate and efficient simulations of large scale problems in elastodynamics.In the DDM-SEM,the original large-scale problem is divided into a number of well designed subdomains.We use the spectral element method independently for each subdomain,and the neighboring subdomains are connected by a frequency-domain version of Riemann transmission condition(RTC)for elastic waves.For the proposed method,we can employ the non-conforming meshes and different interpolation orders in different subdomains to maximize the efficiency.By separating the internal and boundary unknowns of each subdomain,an efficient and naturally parallelizable block LDU direct solver is developed to solve the final system matrix.Numerical experiments verify its accuracy and efficiency,and show that the proposed DDM-SEM can be a promising numerical tool for accurately and effectively solving large and multi-scale problems of elastic waves.It is potentially valuable for the frequency domain seismic inversion where multiple source illuminations are required.展开更多
基金Supported by the Fundamental Research Funds for the Central Universities(ZYGX2021J008)。
文摘A novel substrate integrated microstrip to ultra-thin cavity filter transition operating in the W-band is proposed in this letter.The structure is a new method of connecting microstrip circuits and waveguide filters,and this new structure enables a planar integrated transition from microstrip lines to ultra-thin cavity filters,thereby reducing the size of the transition structure and achieving miniaturization.The structure includes a conventional tapered microstrip transition structure,which guides the electromagnetic field from the microstrip line to the reduced-height dielectric-filled waveguide,and an air-filled matching cavity which is placed between the dielectric-filled waveguide and the ultra-thin cavity filter.The heights of the microstrip line,the dielectric-filled waveguide and the ultra-thin cavity filter are the same,enabling seamless integration within a planar radio-frequency(RF)circuit.To facilitate testing,mature finline transition structures are integrated at both ends of the microstrip line during fabrications.The simulation results of the fabricated microstrip to ultra-thin cavity filter transition with the finline transition structure,with a passband of 91.5-96.5 GHz,has an insertion loss of less than 1.9 dB and a return loss lower than-20 dB.And the whole structure has also been measured which achieves an insertion loss less than 2.6 dB and a return loss lower than-15 dB within the filter's passband,including the additional insertion loss introduced by the finline transitions.Finally,a W-band compact up-conversion module is designed,and the test results show that after using the proposed structure,the module achieves 95 dBc suppression of the 84 GHz local oscillator.It is also demonstrated that the structure proposed in this letter achieves miniaturization of the system integration without compromising the filter performance.
基金the National Key Research and Development Projects(Grant Nos.2021YFB3300601,2021YFB3300603,2021YFB3300604)the Fundamental Research Funds for the Central Universities(No.DUT22QN241)is acknowledged.
文摘To address the challenges associated with multi-sided shells in traditional isogeometric analysis(IGA),this paper introduces a novel isogeometric shell method for trimmed CAD geometries based on toric surfaces and Reissner–Mindlin shell theory.By utilizing toric surface patches,both trimmed and untrimmed elements of the CAD surfaces are represented through a unified geometric framework,ensuring continuity and an accurate geometric description.Toric-Bernstein basis functions are employed to accurately interpolate the geometry and displacement of the trimmed shell.For singularities and corner points on the toric surface,the normal vector is defined as the unit directional vector from the center of curvature to the corresponding control point.Several numerical examples of polygonal shells are presented to evaluate the effectiveness and robustness of the proposed method.This approach significantly simplifies the treatment of trimmed shell IGA and provides a promising solution for simulating complex shell structures with intricate boundaries.
基金supported by the National Natural Science Foundation of China(52172091,52172295)Defense Industrial Technology Development Program(JCKY2023605C002)+3 种基金Basic Research Program of Jiangsu(BK20232013)the National Key Laboratory on Electromagnetic Environmental Effects and Electro-optical Engineering(NO.61422062301)The Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX23_0371,KYCX24_0571,KYCX25_0602)Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(ZHD202305).
文摘Modulating the dipole polarization loss in the single-atom region and establishing its direct relationship with the electromagnetic wave absorption(EWA)performance remain an unmet challenge.Here,a dual-ligand modulation strategy,i.e.,partially changing coordination atoms in the single-metal region(sMr),is introduced to effectively break the coordination symmetry of conjugated metal-organic frameworks(cMOFs),finally enhancing EWA property of cMOFs materials.Further,the asymmetrical sMr is experimentally found to elicit the dipole polarization loss,overcoming the handicaps of other electromagnetic wave loss mechanisms,which directly contribution to enhance EWA performance of this series of cMOFs.This strategy is further confirmed by replacing metal centers.Among studied series of cMOFs,Cu_(2.25)/Co_(0.75)(HHTP1.67HITP0.33)achieves excellent EWA performance with an effective absorption bandwidth of 5.00 GHz and a reflection loss of66.03 dB.We introduce a dual-ligand modulation strategy targeting single-metal regions within cMOFs here,aiming to achieve superior EWA performance through atomic-scale dipole polarization loss modulation.We hope our study can inspire more exploration to realize high-performance EWA materials.
基金Project supported by the National Natural Science Foundation of China(Nos.91752115 and 51776059)
文摘The aerodynamics of gas-particle suspensions is simulated as an Euler-Euler two-fluid model in a revolving rotor over a particle bed. The interactions of collisions between the blade and particles and particle-particle interactions are modeled using the kinetic theory of granular flow(KTGF). The gas turbulence induced by the rotation of the rotor is modeled using the kg-εg model. The flow field of a revolving rotor is simulated using the multiple reference frame(MRF) method. The distributions of velocities, volume fractions, and gas pressure are predicted while the aircraft hovers at different altitudes.The gas pressure decreases from the hub to the tip of the blade, and it is higher at the pressure side than that at the suction side of the rotor. The turbulent kinetic energy of the gas increases toward the blade tip. The volume fraction of particles decreases as the hovering altitude increases. The simulated pressure coefficient is compared with that in experimental measurements.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.51861005 and 51861004)the Innovation Project of Guangxi Graduate Education(No.YCSW2019149)the Guangxi Natural Science Foundation(No.2017GXNSFDA198018)。
文摘Transition metal oxides are ideal electrode materials used for supercapacitors.However,the synthesis of transition metal oxides suffers from drawbacks such as high reaction temperature and energy consumption.Herein,we report the synthesis of sea urchin-like Co3 O4-NiO composites supported on graphene oxide(GO) using a hydrothermal method followed by calcination with a low temperature(250℃).The obtained Co3O4-NiO/GO composite demonstrates a high specific capacitance of 883 F g^-1 at 1 A g^-1.Furthermore,upon coupling with an activated carbon(AC) positive electrode,an asymmetric cell of Co3 O4-NiO/GO//AC exhibits outstanding stability reflected by the high capacitance retention of 82% at a high current density of 10 A g^-1.The excellent electrochemical properties of the composite may be attributed to the good synergistic effect of Co3O4 and NiO,as well as the assembly of Co3 O4 and NiO into a sea urchin structure,which results in increased electron conductivity and more exposed electroactive sites leading to the promotion of the Faradaic redox process.
基金Supported by the National Natural Science Foundation of China(No.61133016)the Sichuan Science and Technology Support Project(No.2013GZ0022)+1 种基金the Scientific Research Fund of Xinjiang Provincial Education Department(No.XJEDU2013128)the Technology Supporting Xinjiang Project(No.201491121)
文摘To alleviate the localization error introduced by irregular sensor network deployment, a new mo bile path localization based on key nodes （MPLPK） protocol is proposed. It can recognize all con cave/convex nodes in the network as fixed anchor nodes, and simplify the following localization process based on these key nodes. The MPLPK protocol is composed of three steps. After all key nodes are found in the network, a mobile node applying improved minimum spanning tree （MST） algorithm is introduced to traverse and locate them. By taking the concave/convex nodes as anchors, the complexity of the irregular network can be degraded. And the simulation results demonstrate that MPEPK has 20% to 40% accuracy improvements than connectivity-based and anchor-free three-di- mensional localization （CATL） and approximate convex decomposition based localization （ACDL）.
基金supported by the National Natural Science Foundation of China(Grant No.61334002)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory of China(Grant No.ZHD201206)
文摘The behavior of Schottky contacts in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated by temperature-dependent current-voltage （T-I-V） measurements from 300 K to 473 K. The ideality factor and barrier height determined based on the thermionic emission （TE） theory are found to be strong functions of temperature, while present a great deviation from the theoretical value, which can be expounded by the barrier height inhomogeneities. In order to determine the forward current transport mechanisms, the experimental data are analyzed using numerical fitting method, considering the temperature-dependent series resistance. It is observed that the current flow at room temperature can be attributed to the tunneling mechanism, while thermionic emission current gains a growing proportion with an increase in temperature. Finally, the effective barrier height is derived based on the extracted thermionic emission component, and an evaluation of the density of dislocations is made from the I-V characteristics, giving a value of 1.49 × 10^7 cm^-2.
基金supported by the National Natural Science Foundation of China(No.51374190)the Major Equipment Fund of Chinese Academy of Sciences(No.YZ201567)
文摘Lorentz force velocimetry(LFV) is a noncontact technique for measuring electrically conducting fluids based on the principle of electromagnetic induction. This work aims to answer the open and essential question of whether LFV can work properly under a surrounding external magnetic field(ExMF). Two types of Ex MFs with different magnetic intensities were examined: a magnetic field with a typical order of 0.4 T generated by a permanent magnet(PM) and another generated by an electromagnet(EM) on the order of 2 T. Two forces, including the magnetostatic force between the Ex MF and PM in the LFV, and the Lorentz force generated by the PM in LFV were measured and analyzed in the experiment. In addition,Ex MFs of varying strengths were added to the LFV, and the location of the LFV device in the iron cores of the EM was considered. The experimental outcomes demonstrate that it is possible for a LFV device to operate normally under a moderate Ex MF. However, the magnetostatic force will account for a high proportion of the measured force,thus inhibiting the normal LFV operation, if the Ex MF is too high.
文摘With science and technology development,vibration testing as the most important item in reliability test is becoming more and more important,at the same time,vibrate condition becoming more and more complicated,the phenomenon increases that the output of controller goes beyond controlling range so that destroy the specimen. In this paper,some skills such as how to set the parameters of force controller,where to place the sensor,which material to be chosen and which skills to be used while making jigs were introduced to avoid the just matter. At last,some examples were given to prove the validity of the method proposed.
文摘As the process of economic globalization deepens,a large variety of integrated circuit designers tends to move the chip's manufacturing to the developing country.But during the globalization of semiconductor design and fabrication process,integrated circuits are suffering from increasing malicious alterations from the untrusted foundries,which pose a serious threat to the military,finance,transportation and other critical systems.An noninvasive approach was presented to measure the physical "sidechannel"parameter of a chip such as current or delay,which is effectively capable of detecting the malicious hardware alternations.The intrinsic relationship of a circuit's side-channel parameters was exploited to distinguish the effect of a Trojan in the presence of large random noise and process noise,such as the Dynamic current(IDDT)versus the maximum operating frequency(Fmax)correlation.The Monte Carlo analysis in Hspice using ± 20% Gauss variations in transistor threshold voltage(Vth)was carried out to simulate the circuit state in the real world.Simulation Results show that this approach is effective to detect the ultra-small Trojans.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11290152,11427801,and 11902220)the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality,China(PHRIHLB).
文摘High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather.Moreover,transversely galloping will be excited due to the irregular structure resulting from the alternation of lift force and drag force.In this paper,the nonlinear dynamics and internal resonance of an iced cable under wind excitation are investigated.Considering the excitation caused by pulsed wind and the movement of the support,the nonlinear governing equations of motion of the iced cable are established using a three-degree-of-freedom model based on Hamilton's principle.By the Galerkin method,the partial differential equations are then discretized into ordinary differential equations.The method of multiple scales is then used to obtain the averaged equations of the iced cable,and the principal parametric resonance-1/2 subharmonic resonance and the 2:1 internal resonance are considered.The numerical simulations are performed to investigate the dynamic response of the iced cable.It is found that there exist periodic,multi-periodic,and chaotic motions of the iced cable subjected to wind excitation.
基金This work was supported by the Major Program of National Natural Science Foundation of China(11290141).
文摘Signature,widely used in cloud environment,describes the work as readily identifying its creator.The existing signature schemes in the literature mostly rely on the Hardness assumption which can be easily solved by quantum algorithm.In this paper,we proposed an advanced quantum-resistant signature scheme for Cloud based on Eisenstein Ring(ETRUS)which ensures our signature scheme proceed in a lattice with higher density.We proved that ETRUS highly improve the performance of traditional lattice signature schemes.Moreover,the Norm of polynomials decreases significantly in ETRUS which can effectively reduce the amount of polynomials convolution calculation.Furthermore,storage complexity of ETRUS is smaller than classical ones.Finally,according to all convolution of ETRUS enjoy lower degree polynomials,our scheme appropriately accelerate 56.37%speed without reducing its security level.
基金supported by the National Natural Science Foundation of China(No.52172295)Basic Research Program of Jiangsu(No.BK20232013)+2 种基金Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(No.ZHD202305)Postgraduate Research&Practice Innovation Program of Jiangsu Province(Nos.KYCX24_0571 and KYCX25_0602)Interdisciplinary Innovation Fund for Doctoral Students of Nanjing University of Aeronautics and Astronautics(No.KXKCXJJ202408)。
文摘The wide application of electromagnetic technology has led to increasingly frequent information transmission and communication interconnection.When the intensity of the disordered radiation of electromagnetic waves is too high,it will cause electromagnetic pollution and pose a huge threat to human health or the survival of other animals and plants.How to ingeniously design absorbing materials is the key to solving the problem.This paper proposes a new design concept.The Co-based zeolite imidazolite-structured material ZIF-67 was selected as the main body of the metal-organic frameworks(MOFs)template,and the dodecahedral structured ZIF-67 nanoparticles were prepared using the classic ion-ligand process.Subsequently,a dodecahedral NiCo-LDH nanoparticle precursor composed of NiCo bimetallic hydroxide nanosheets with hollow edges and interior was obtained based on the liquid-phase cationic etching process.On this basis,thioacetamide(TAA)was selected as the vulcanizing agent,and the ZIF-67-derived sulfide inheriting the micro-nano structure of the precursor was obtained through liquid-phase hydrothermal vulcanization.The vulcanization growth mechanism and electromagnetic wave absorption mechanism of the MOF_(S)-derived sulfide were deeply explored.
基金supported by the National Natural Science Foundation of China(51672245 and 61735017)the National Key Basic Research Program of China(2015CB352003)+2 种基金Zhejiang Provincial Natural Science Foundation of China(R17F050003)the Fundamental Research Funds for the Central Universitiesthe Program for Zhejiang Leading Team of S&T Innovation
文摘Quasi-one-dimensional semiconductor nanostructure-based photodetectors show high sensitivity but suffer from slow response speed due to surface reaction. Here, we report a fast-response CdS-CdSxTei-x-CdTe core-shell nanobelt photodetector with a rise time of 11 /.is, which is the fastest among CdS based photodetectors reported previously. The improved response speed is ascribed to the sup-pressed possibilities of surface reaction resulting from the core-shell structure and heterojunction among the CdS, CdSxTel-x and CdTe. The measured response spectrum of CdS-CdSxTe1-x-CdTe core-shell nano-belt photodetector covers a wide range from 355 to 785 nm. Moreover, high responsivity （1,520 A/W） and large 3 dB bandwidth （~22.9 kHz） are obtained along with the fast response, The high performance in responsivity, sensitivity, spectral response and photoresponse speed makes this device a promising candidate for practical application in optical sensing, communication and imaging.
基金the National Natural Science Foundation of China(Grant Nos.41390453,62001408)the National Key R&D Program of the Ministry of Science and Technology of China(Grant No.2018YFC0603503)the Special Program for Applied Research on Super Computation of the NSFC-Guangdong Joint Fund(Grant No.U1501501)。
文摘We propose a domain decomposition method based on the spectral element method(DDM-SEM)for elastic wave computation in frequency domain.It combines the high accuracy of the spectral element method and the high degree of parallelism of a domain decomposition technique,which makes this method suitable for accurate and efficient simulations of large scale problems in elastodynamics.In the DDM-SEM,the original large-scale problem is divided into a number of well designed subdomains.We use the spectral element method independently for each subdomain,and the neighboring subdomains are connected by a frequency-domain version of Riemann transmission condition(RTC)for elastic waves.For the proposed method,we can employ the non-conforming meshes and different interpolation orders in different subdomains to maximize the efficiency.By separating the internal and boundary unknowns of each subdomain,an efficient and naturally parallelizable block LDU direct solver is developed to solve the final system matrix.Numerical experiments verify its accuracy and efficiency,and show that the proposed DDM-SEM can be a promising numerical tool for accurately and effectively solving large and multi-scale problems of elastic waves.It is potentially valuable for the frequency domain seismic inversion where multiple source illuminations are required.
