We investigated the electric controllable spin-filtering effect in a zigzag phosphorene nanoribbon(ZPNR) based normal–antiferromagnet–normal junction. Two ferromagnets are closely coupled to the edges of the nanorib...We investigated the electric controllable spin-filtering effect in a zigzag phosphorene nanoribbon(ZPNR) based normal–antiferromagnet–normal junction. Two ferromagnets are closely coupled to the edges of the nanoribbon and form the edge-to-edge antiferromagnetism. Under an in-plane electric field, the two degenerate edge bands of the edge-to-edge antiferromagnet split into four spin-polarized sub-bands and a 100% spin-polarized current can be easily induced with the maximal conductance 2e~2/h. The spin polarization changes with the strength of the electric field and the exchange field,and changes sign at opposite electric fields. The spin-polarized current switches from one edge to the other by reversing the direction of the electric field. The edge current can also be controlled spatially by changing the electric potential of the scattering region. The manipulation of edge current is useful in spin-transfer-torque magnetic random-access memory and provides a practical way to develop controllable spintronic devices.展开更多
The frequency selective surface (FSS) has been widely applied by means of its spatial frequency-filter characteristic, but it is always designed and used as a device with fixed frequency response. In order to tune the...The frequency selective surface (FSS) has been widely applied by means of its spatial frequency-filter characteristic, but it is always designed and used as a device with fixed frequency response. In order to tune the resonant frequency and switch the frequency channel, a scheme of mechanically tunable FSS is theoretically analyzed by using the method of Floquet's vector modes expansion and fields matching. A double-layer tunable FSS with dipole element can perform a dynamic range of resonant frequency covering whole X-band.展开更多
A high channel-count comb filter based on multi-concatenated sampled chirped fiber Bragg gratings (MC- SCFBGs) is proposed and optimally designed by using several chirped gratings with different fundamental grating ...A high channel-count comb filter based on multi-concatenated sampled chirped fiber Bragg gratings (MC- SCFBGs) is proposed and optimally designed by using several chirped gratings with different fundamental grating periods, instead of non-grating sections of SCFBGs. The numerical simulations of the reflection spectra show that the channel spacing and the channel bandwidth in MC-SCFBGs are smaller than those in multi-concatenated chirped fiber Bragg gratings (MC-CFBGs) and that the spectral bandwidth of MC-SCFBGs can be greatly broadened by increasing the cascade number of the grating sections in each samDling Deriod.展开更多
There have been few investigations of effects of electrical charge, carried by lab-generated particles, on filtration efficiency testing. Here, we measured the elementary charge on particles and the fraction of partic...There have been few investigations of effects of electrical charge, carried by lab-generated particles, on filtration efficiency testing. Here, we measured the elementary charge on particles and the fraction of particles carrying that charge with a combined electrometer, differential mobility analyzer, and scanning mobility particle sizer. A typical solid NaCI aerosol and liquid diethylhexyl sebacate (DEHS) aerosol were generated with Collison and Laskin nebulizers, respectively. Our experimental results showed that NaCI aerosols carried more charge after aerosol generation. The average net elementary charge per particle was approximately 0.07. The NaCI aerosol was overall positively charged but contained a mixture of neutral and charged particles. Individual particles could carry at most four elementary charges. According to constant theorem, we speculated that original NaC1 aerosol contained 17% neutral, 45% positive-, and 38% negative-charged particles in the diameter range from 30 to 300nm. A Kr-85 neutralizer was used to decrease the charge on the NaCI particles. Our results indicated that the DEHS aerosol was electrically neutral. The effects of electric charge on particle collection by electret and electroneutral high efficiency particulate air (HEPA) filters were analyzed. Theoretical calculations suggested that charges on original NaCI aerosol particles enhanced the filtration efficiency of HEPA filters,展开更多
In order to realize wideband filtering properties of frequency selective surface (FSS), FSS of closely packed elements is presented. The Y loop elements are chosen as the graphics elements. Based on the spectral dom...In order to realize wideband filtering properties of frequency selective surface (FSS), FSS of closely packed elements is presented. The Y loop elements are chosen as the graphics elements. Based on the spectral domain method, the frequency response is analyzed for different incident angles and polarizations. The result of the numerical analysis shows that the dense FSS has wide passband with better independence of angle and polarization.展开更多
An asymmetric Jerusalem unit and the frequency selective surface (FSS) structure composed of such units are designed. The transmittance of the designed FSS structure is calculated by mode-matching method and compare...An asymmetric Jerusalem unit and the frequency selective surface (FSS) structure composed of such units are designed. The transmittance of the designed FSS structure is calculated by mode-matching method and compared with the test results. The comparison results show that the FSS center frequency of the asymmetric structure unit drifts little with the variation of the incident angles of the electromagnetic waves and keeps relatively stable. The research offers a new choice for the application of FSS under the large scanning angle of electromagnetic waves.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12174077 and 12174051)the Science Foundation of GuangDong Province (Grant No.2021A1515012363)GuangDong Basic and Applied Basic Research Foundation (Grant No.2022A1515110011)。
文摘We investigated the electric controllable spin-filtering effect in a zigzag phosphorene nanoribbon(ZPNR) based normal–antiferromagnet–normal junction. Two ferromagnets are closely coupled to the edges of the nanoribbon and form the edge-to-edge antiferromagnetism. Under an in-plane electric field, the two degenerate edge bands of the edge-to-edge antiferromagnet split into four spin-polarized sub-bands and a 100% spin-polarized current can be easily induced with the maximal conductance 2e~2/h. The spin polarization changes with the strength of the electric field and the exchange field,and changes sign at opposite electric fields. The spin-polarized current switches from one edge to the other by reversing the direction of the electric field. The edge current can also be controlled spatially by changing the electric potential of the scattering region. The manipulation of edge current is useful in spin-transfer-torque magnetic random-access memory and provides a practical way to develop controllable spintronic devices.
文摘The frequency selective surface (FSS) has been widely applied by means of its spatial frequency-filter characteristic, but it is always designed and used as a device with fixed frequency response. In order to tune the resonant frequency and switch the frequency channel, a scheme of mechanically tunable FSS is theoretically analyzed by using the method of Floquet's vector modes expansion and fields matching. A double-layer tunable FSS with dipole element can perform a dynamic range of resonant frequency covering whole X-band.
基金supported by the National Natural Science Foundation of China (Nos. 60977048 and 60978058)the Natural Science Foundation of Ningbo(No. 2008A610001)+1 种基金the International Collaboration Project of Ningbo (No. 2010D10018)the K. C.Wong Magna Fund in Ningbo University,China
文摘A high channel-count comb filter based on multi-concatenated sampled chirped fiber Bragg gratings (MC- SCFBGs) is proposed and optimally designed by using several chirped gratings with different fundamental grating periods, instead of non-grating sections of SCFBGs. The numerical simulations of the reflection spectra show that the channel spacing and the channel bandwidth in MC-SCFBGs are smaller than those in multi-concatenated chirped fiber Bragg gratings (MC-CFBGs) and that the spectral bandwidth of MC-SCFBGs can be greatly broadened by increasing the cascade number of the grating sections in each samDling Deriod.
基金This work was financially supported by Beijing Natural Science Foundation (Grant No. 8142023), Beijing Science and Technology Plan (Grant No. Z161100000716004), and The Science Fund for Creative Research Groups of National Natural Science Foundation of China (Grant No. 51321002).
文摘There have been few investigations of effects of electrical charge, carried by lab-generated particles, on filtration efficiency testing. Here, we measured the elementary charge on particles and the fraction of particles carrying that charge with a combined electrometer, differential mobility analyzer, and scanning mobility particle sizer. A typical solid NaCI aerosol and liquid diethylhexyl sebacate (DEHS) aerosol were generated with Collison and Laskin nebulizers, respectively. Our experimental results showed that NaCI aerosols carried more charge after aerosol generation. The average net elementary charge per particle was approximately 0.07. The NaCI aerosol was overall positively charged but contained a mixture of neutral and charged particles. Individual particles could carry at most four elementary charges. According to constant theorem, we speculated that original NaC1 aerosol contained 17% neutral, 45% positive-, and 38% negative-charged particles in the diameter range from 30 to 300nm. A Kr-85 neutralizer was used to decrease the charge on the NaCI particles. Our results indicated that the DEHS aerosol was electrically neutral. The effects of electric charge on particle collection by electret and electroneutral high efficiency particulate air (HEPA) filters were analyzed. Theoretical calculations suggested that charges on original NaCI aerosol particles enhanced the filtration efficiency of HEPA filters,
基金the Knowledge Innovation Program of Chinese Academy of Sciences and the Specialized Research Foundation for the Gainer of Outstanding Doctoral Thesis and Presidential Scholarship of Chinese Academy of Sciences(No.076231J070)
文摘In order to realize wideband filtering properties of frequency selective surface (FSS), FSS of closely packed elements is presented. The Y loop elements are chosen as the graphics elements. Based on the spectral domain method, the frequency response is analyzed for different incident angles and polarizations. The result of the numerical analysis shows that the dense FSS has wide passband with better independence of angle and polarization.
基金supported by the National Natural Science Foundation of China under Grant No.10647105
文摘An asymmetric Jerusalem unit and the frequency selective surface (FSS) structure composed of such units are designed. The transmittance of the designed FSS structure is calculated by mode-matching method and compared with the test results. The comparison results show that the FSS center frequency of the asymmetric structure unit drifts little with the variation of the incident angles of the electromagnetic waves and keeps relatively stable. The research offers a new choice for the application of FSS under the large scanning angle of electromagnetic waves.