Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively...Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38%(4.05 GHz–5.95 GHz)and AR bandwidth of 24.9%(4.4 GHz–5.65 GHz). The bandwidth of the high gain antenna can reach 42.7%(3.95 GHz–6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.展开更多
This study established a novel method for the simultaneous detection of two-component gases.Radio frequency(RF)white noise disturbance laser current and wavelength modulation were simultaneously used to improve the of...This study established a novel method for the simultaneous detection of two-component gases.Radio frequency(RF)white noise disturbance laser current and wavelength modulation were simultaneously used to improve the off-axis integrated cavity output spectroscopy technique,and a high-precision dual modulation OA-ICOS(RF-WM-OA-ICOS)system was established.The two laser beams were coupled into one laser beam that was applied incident to the cavity of RF-WM-OA-ICOS system.The second harmonic signals of CH_(4)and CO_(2)gas simultaneously appeared in the rising or falling edge of a triangular wave.This method was used to measure CH_(4)and CO_(2)with different concentrations.The results indicated that the proposed system has high stability and can accurately and simultaneously measure the concentrations of CH_(4)and CO_(2),with an optimal integration time of 220 s.The minimum detection limit was 10 ppb for CH_(4)and 1.5 ppm for CO_(2).The corresponding noise equivalent absorption sensitivity values were calculated as 2.67×10^(-13)cm^(-1)·Hz^(-1/2)and 5.18×10^(-11)cm^(-1)·Hz^(-1/2),respectively.The proposed dual-component gas simultaneous detection method can also be used for high-precision simultaneous detection of other gases.Therefore,this study may serve as a reference for developing portable multicomponent gas analyzers.展开更多
A new off-axis integrated cavity output spectroscopy (ICOS) is coupled to Weiss equilibrator for continuous high- resolution dissolved methane measurement in the surface ocean. The time constant for the equilibrator...A new off-axis integrated cavity output spectroscopy (ICOS) is coupled to Weiss equilibrator for continuous high- resolution dissolved methane measurement in the surface ocean. The time constant for the equilibrator in freshwater at room temperature is determined via dis-equilibration and re-equilibration experiments. The constant for methane is about 40 min. The system is calibrated using a standard gas of 3.980×10-6, and the precision of the ICOS for methane is 0.07%. This system is equipped onboard to measure the spatial distribution in methane concentrations of South Yellow Sea (SYS) along the cruise track from Shanghai to Qingdao. Result shows that the methane concentration varies from 2.79 to 36.36 nmol/L, reveals a significant pattern of methane source in SYS, and a distinct decreasing trend from south to north. The peak value occurs at the coast area outside mouth of the Changjiang River, likely to be affected by the Changjiang diluted water mass dissolving a large amount of rich in methane. Moreover, all the surface waters are oversaturated, air-to-sea fluxes range from 98.59 to 5 485.35 μmol/(m2·d) (average value (1 169.74±1 398.46) μmol/(m2·d)), indicating a source region for methane to the atmosphere. Key words: methane, equilibrator, off-axis integrated cavity output spectroscopy (ICOS), South Yellow Sea展开更多
This paper presents a high-order coupled compact integrated RBF(CC IRBF)approximation based domain decomposition(DD)algorithm for the discretisation of second-order differential problems.Several Schwarz DD algorithms,...This paper presents a high-order coupled compact integrated RBF(CC IRBF)approximation based domain decomposition(DD)algorithm for the discretisation of second-order differential problems.Several Schwarz DD algorithms,including one-level additive/multiplicative and two-level additive/multiplicative/hybrid,are employed.The CCIRBF based DD algorithms are analysed with different mesh sizes,numbers of subdomains and overlap sizes for Poisson problems.Our convergence analysis shows that the CCIRBF two-level multiplicative version is the most effective algorithm among various schemes employed here.Especially,the present CCIRBF two-level method converges quite rapidly even when the domain is divided into many subdomains,which shows great promise for either serial or parallel computing.For practical tests,we then incorporate the CCIRBF into serial and parallel two-level multiplicative Schwarz.Several numerical examples,including those governed by Poisson and Navier-Stokes equations are analysed to demonstrate the accuracy and efficiency of the serial and parallel algorithms implemented with the CCIRBF.Numerical results show:(i)the CCIRBF-Serial and-Parallel algorithms have the capability to reach almost the same solution accuracy level of the CCIRBF-Single domain,which is ideal in terms of computational calculations;(ii)the CCIRBF-Serial and-Parallel algorithms are highly accurate in comparison with standard finite difference,compact finite difference and some other schemes;(iii)the proposed CCIRBF-Serial and-Parallel algorithms may be used as alternatives to solve large-size problems which the CCIRBF-Single domain may not be able to deal with.The ability of producing stable and highly accurate results of the proposed serial and parallel schemes is believed to be the contribution of the coarse mesh of the two-level domain decomposition and the CCIRBF approximation.It is noted that the focus of this paper is on the derivation of highly accurate serial and parallel algorithms for second-order differential problems.The scope of this work does not cover a thorough analysis of computational time.展开更多
We design a hybrid integrated chaotic semiconductor laser with short-cavity optical feedback. It can be assembled in a commercial butterfly shell with just three micro-lenses. One of them is coated by a transflective ...We design a hybrid integrated chaotic semiconductor laser with short-cavity optical feedback. It can be assembled in a commercial butterfly shell with just three micro-lenses. One of them is coated by a transflective film to provide the optical feedback for chaos generation while insuring regular laser transmission. We prove the feasibility of the chaos generation in this compact structure and provide critical external parameters for the fabrication by theoretical simulations. Rather than the usual changeless internal parameters used in previous simulation research, we extract the real parameters of the chip by experiment. Moreover, the maps of the largest Lyapunov exponent with varying bias current and feedback intensity Kap demonstrate the dynamic characteristics under different external-cavity conditions. Each laser chip has its own optimal external cavity length(L) and feedback intensity(Kap) to generate chaos because of the different internal parameters. We have acquired two ranges of optimal parameters(L = 4 mm, 0.12 〈 Kap 〈 0.2 and L = 5 mm, 0.07 〈 Kap 〈 0.12) for two different chips.展开更多
Three dual-mode band-pass filters are presented in the present paper. The first filter is realized by dual-mode substrate integrated waveguide (SIW) cavity;the second is based on the integration of SIW cavity with ele...Three dual-mode band-pass filters are presented in the present paper. The first filter is realized by dual-mode substrate integrated waveguide (SIW) cavity;the second is based on the integration of SIW cavity with electromagnetic band gap (EBG);and the third is based on the integration of SIW cavity with complementary split ring resonator (CSRR). The dual-mode SIW cavity is designed to have a fractional bandwidth of 4.95% at the midband frequency of 9.08 GHz;the proposed EBG-SIW resonator operates at 9.12 GHz with a bandwidth of 4.38% and the CSRR-SIW resonator operates at 8.66 GHz with a bandwidth of 2.54%. The proposed filters have the high Q-factors and generate a transmission zero in upper stopband, and these by the use of Rogers RT/duriod 5880 (tm).展开更多
In this paper,the dynamic stress concentration and scattering of SH-waves by bi-material structures that possess an interface elliptic cavity are investigated.First,by using the complex function method,the Green's...In this paper,the dynamic stress concentration and scattering of SH-waves by bi-material structures that possess an interface elliptic cavity are investigated.First,by using the complex function method,the Green's function is constructed.This yields the solution of the displacement field for an elastic half space with a semi-elliptic canyon impacted by an anti-plane harmonic line source loading on the horizontal surface.Then,the problem is divided into an upper and lower half space along the horizontal interface,regarded as a harmony model.In order to satisfy the integral continuity condition, the unknown anti-plane forces are applied to the interface.The integral equations with unknown forces can be established through the continuity condition,and after transformation,the algebraic equations are solved numerically.Finally,the distribution of the dynamic stress concentration factor(DSCF)around the elliptic cavity is given and the effect of different parameters on DSCF is discussed.展开更多
The transient response of an unlimited cylindrical cavity buried in the infinite elastic soil subjected to an anti-plane impact load along the cavern axis direction was studied.Using Laplace transform combining with c...The transient response of an unlimited cylindrical cavity buried in the infinite elastic soil subjected to an anti-plane impact load along the cavern axis direction was studied.Using Laplace transform combining with contour integral of the Laplace inverse transform specifically,the general analytical expressions of the soil displacement and stress are obtained in the time domain,respectively.And the numerical solutions of the problem computed by analytical expressions are presented.In the time domain,the dynamic responses of the infinite elastic soil are analyzed,and the calculation results are compared with those from numerical inversion proposed by Durbin and the static results.One observes good agreement between analytical and numerical inversion results,lending the further support to the method presented.Finally,some valuable shear wave propagation laws are gained: the displacement of the soil remains zero before the wave arrival,and after the shear wave arrival,the stress and the displacement at this point increase abruptly,then reduce and tend to the static value gradually at last.The wave attenuates along the radial,therefore the farther the wave is from the source,the smaller the stress and the displacement are,and the stress and the displacement are just functions of the radial distance from the axis.展开更多
In this paper, we give a hybrid method to numerically solve the inverse open cavity scattering problem for cavity shape, given the scattered solution on the opening of the cavity. This method is a hybrid between an it...In this paper, we give a hybrid method to numerically solve the inverse open cavity scattering problem for cavity shape, given the scattered solution on the opening of the cavity. This method is a hybrid between an iterative method and an integral equations method for solving the Cauchy problem. The idea of this hybrid method is simple, the operation is easy, and the computation cost is small. Numerical experiments show the feasibility of this method, even for cases with noise.展开更多
Integrated cavity output spectroscopy(ICOS) is an effective technique in trace gase detection.The strong absorption due to the long optical path of this method makes it challenging in the application scenes that have ...Integrated cavity output spectroscopy(ICOS) is an effective technique in trace gase detection.The strong absorption due to the long optical path of this method makes it challenging in the application scenes that have large gas concentration fluctuation,especially when the gas concentration is high.In this paper,we demonstrate an extension of the dynamic range of ICOS by using a detuned laser combined with an off-axis integrating cavity.With this,we improve the upper limit of the dynamic detection range from 0.1%(1000 ppm) to 20% of the gas concentration.This method provides a way of using ICOS in the applications with unpredictable gas concentrations such as gas leak detection,ocean acidification,carbon sequestration,etc.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No.61871394)。
文摘Two substrate integrated waveguide(SIW) cavity antenna arrays based on metasurface are proposed in this paper. By rotating the metasurface element, circularly polarized and high gain antennas are achieved respectively. Firstly, multi-mode resonance theory is employed to broaden the bandwidth of the slot antenna. And then, an SIW cavity composed of 4×4 cornercut elements is added on the top of the slot antenna to achieve the circular polarization and improve the front-to-back ratio. Thirdly, the metasurface elements are sequentially rotated and a high gain antenna with 2-dBi enhancement on average in the operation band is obtained. Based on the two antenna units, two 2×2 antenna arrays are designed. The circularly polarized and high gain antenna arrays are both fabricated to verify the correctness. Furthermore, the novel wideband phase shifter is employed in the circularly polarized antenna to obtain an operating bandwidth of 38%(4.05 GHz–5.95 GHz)and AR bandwidth of 24.9%(4.4 GHz–5.65 GHz). The bandwidth of the high gain antenna can reach 42.7%(3.95 GHz–6.1 GHz) and with the gain enhancement of 2 dBi compared with that of the circularly polarized antenna. The gain remains steady in most of operating band within a variation of 1 dBi. It is remarkable that the rotating of the metasurface element has a great influence on the antenna performance, which provides a new explication for the multi-function antenna design.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.62005108 and 62205134)the National Key Research and Development Program of China(Grant No.2022YFC2807701)the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(Grant Nos.20KJB140009 and 21KJB140008)。
文摘This study established a novel method for the simultaneous detection of two-component gases.Radio frequency(RF)white noise disturbance laser current and wavelength modulation were simultaneously used to improve the off-axis integrated cavity output spectroscopy technique,and a high-precision dual modulation OA-ICOS(RF-WM-OA-ICOS)system was established.The two laser beams were coupled into one laser beam that was applied incident to the cavity of RF-WM-OA-ICOS system.The second harmonic signals of CH_(4)and CO_(2)gas simultaneously appeared in the rising or falling edge of a triangular wave.This method was used to measure CH_(4)and CO_(2)with different concentrations.The results indicated that the proposed system has high stability and can accurately and simultaneously measure the concentrations of CH_(4)and CO_(2),with an optimal integration time of 220 s.The minimum detection limit was 10 ppb for CH_(4)and 1.5 ppm for CO_(2).The corresponding noise equivalent absorption sensitivity values were calculated as 2.67×10^(-13)cm^(-1)·Hz^(-1/2)and 5.18×10^(-11)cm^(-1)·Hz^(-1/2),respectively.The proposed dual-component gas simultaneous detection method can also be used for high-precision simultaneous detection of other gases.Therefore,this study may serve as a reference for developing portable multicomponent gas analyzers.
基金The Scientific Research Foundation of Third Institute of Oceangraphy under contract No.2013004the National Natural Science Foundation of China(NSFC)under contract Nos 40906102 and 41230529the CHINARE under contract Nos 2012–2013(01–04–02),(01–02–01)and(03–04–02)
文摘A new off-axis integrated cavity output spectroscopy (ICOS) is coupled to Weiss equilibrator for continuous high- resolution dissolved methane measurement in the surface ocean. The time constant for the equilibrator in freshwater at room temperature is determined via dis-equilibration and re-equilibration experiments. The constant for methane is about 40 min. The system is calibrated using a standard gas of 3.980×10-6, and the precision of the ICOS for methane is 0.07%. This system is equipped onboard to measure the spatial distribution in methane concentrations of South Yellow Sea (SYS) along the cruise track from Shanghai to Qingdao. Result shows that the methane concentration varies from 2.79 to 36.36 nmol/L, reveals a significant pattern of methane source in SYS, and a distinct decreasing trend from south to north. The peak value occurs at the coast area outside mouth of the Changjiang River, likely to be affected by the Changjiang diluted water mass dissolving a large amount of rich in methane. Moreover, all the surface waters are oversaturated, air-to-sea fluxes range from 98.59 to 5 485.35 μmol/(m2·d) (average value (1 169.74±1 398.46) μmol/(m2·d)), indicating a source region for methane to the atmosphere. Key words: methane, equilibrator, off-axis integrated cavity output spectroscopy (ICOS), South Yellow Sea
文摘This paper presents a high-order coupled compact integrated RBF(CC IRBF)approximation based domain decomposition(DD)algorithm for the discretisation of second-order differential problems.Several Schwarz DD algorithms,including one-level additive/multiplicative and two-level additive/multiplicative/hybrid,are employed.The CCIRBF based DD algorithms are analysed with different mesh sizes,numbers of subdomains and overlap sizes for Poisson problems.Our convergence analysis shows that the CCIRBF two-level multiplicative version is the most effective algorithm among various schemes employed here.Especially,the present CCIRBF two-level method converges quite rapidly even when the domain is divided into many subdomains,which shows great promise for either serial or parallel computing.For practical tests,we then incorporate the CCIRBF into serial and parallel two-level multiplicative Schwarz.Several numerical examples,including those governed by Poisson and Navier-Stokes equations are analysed to demonstrate the accuracy and efficiency of the serial and parallel algorithms implemented with the CCIRBF.Numerical results show:(i)the CCIRBF-Serial and-Parallel algorithms have the capability to reach almost the same solution accuracy level of the CCIRBF-Single domain,which is ideal in terms of computational calculations;(ii)the CCIRBF-Serial and-Parallel algorithms are highly accurate in comparison with standard finite difference,compact finite difference and some other schemes;(iii)the proposed CCIRBF-Serial and-Parallel algorithms may be used as alternatives to solve large-size problems which the CCIRBF-Single domain may not be able to deal with.The ability of producing stable and highly accurate results of the proposed serial and parallel schemes is believed to be the contribution of the coarse mesh of the two-level domain decomposition and the CCIRBF approximation.It is noted that the focus of this paper is on the derivation of highly accurate serial and parallel algorithms for second-order differential problems.The scope of this work does not cover a thorough analysis of computational time.
基金Project supported by the International Science and Technology Cooperation Program of China(Grant No.2014DFA50870)the National Natural Science Foundation of China(Grant Nos.61377089,61475111,and 61527819)+4 种基金Shanxi Province Natural Science Foundation,China(Grant No.2015011049)Shanxi Province Youth Science and Technology Foundation,China(Grant No.201601D021069)Shanxi Scholarship Council of China(Grant No.2016-036)Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi,ChinaProgram for Sanjin Scholar,China
文摘We design a hybrid integrated chaotic semiconductor laser with short-cavity optical feedback. It can be assembled in a commercial butterfly shell with just three micro-lenses. One of them is coated by a transflective film to provide the optical feedback for chaos generation while insuring regular laser transmission. We prove the feasibility of the chaos generation in this compact structure and provide critical external parameters for the fabrication by theoretical simulations. Rather than the usual changeless internal parameters used in previous simulation research, we extract the real parameters of the chip by experiment. Moreover, the maps of the largest Lyapunov exponent with varying bias current and feedback intensity Kap demonstrate the dynamic characteristics under different external-cavity conditions. Each laser chip has its own optimal external cavity length(L) and feedback intensity(Kap) to generate chaos because of the different internal parameters. We have acquired two ranges of optimal parameters(L = 4 mm, 0.12 〈 Kap 〈 0.2 and L = 5 mm, 0.07 〈 Kap 〈 0.12) for two different chips.
文摘Three dual-mode band-pass filters are presented in the present paper. The first filter is realized by dual-mode substrate integrated waveguide (SIW) cavity;the second is based on the integration of SIW cavity with electromagnetic band gap (EBG);and the third is based on the integration of SIW cavity with complementary split ring resonator (CSRR). The dual-mode SIW cavity is designed to have a fractional bandwidth of 4.95% at the midband frequency of 9.08 GHz;the proposed EBG-SIW resonator operates at 9.12 GHz with a bandwidth of 4.38% and the CSRR-SIW resonator operates at 8.66 GHz with a bandwidth of 2.54%. The proposed filters have the high Q-factors and generate a transmission zero in upper stopband, and these by the use of Rogers RT/duriod 5880 (tm).
文摘In this paper,the dynamic stress concentration and scattering of SH-waves by bi-material structures that possess an interface elliptic cavity are investigated.First,by using the complex function method,the Green's function is constructed.This yields the solution of the displacement field for an elastic half space with a semi-elliptic canyon impacted by an anti-plane harmonic line source loading on the horizontal surface.Then,the problem is divided into an upper and lower half space along the horizontal interface,regarded as a harmony model.In order to satisfy the integral continuity condition, the unknown anti-plane forces are applied to the interface.The integral equations with unknown forces can be established through the continuity condition,and after transformation,the algebraic equations are solved numerically.Finally,the distribution of the dynamic stress concentration factor(DSCF)around the elliptic cavity is given and the effect of different parameters on DSCF is discussed.
文摘The transient response of an unlimited cylindrical cavity buried in the infinite elastic soil subjected to an anti-plane impact load along the cavern axis direction was studied.Using Laplace transform combining with contour integral of the Laplace inverse transform specifically,the general analytical expressions of the soil displacement and stress are obtained in the time domain,respectively.And the numerical solutions of the problem computed by analytical expressions are presented.In the time domain,the dynamic responses of the infinite elastic soil are analyzed,and the calculation results are compared with those from numerical inversion proposed by Durbin and the static results.One observes good agreement between analytical and numerical inversion results,lending the further support to the method presented.Finally,some valuable shear wave propagation laws are gained: the displacement of the soil remains zero before the wave arrival,and after the shear wave arrival,the stress and the displacement at this point increase abruptly,then reduce and tend to the static value gradually at last.The wave attenuates along the radial,therefore the farther the wave is from the source,the smaller the stress and the displacement are,and the stress and the displacement are just functions of the radial distance from the axis.
基金Supported by Major State Research Development Program of China(2005CB321701)National Natural Science Foundation of China(10971083)
文摘In this paper, we give a hybrid method to numerically solve the inverse open cavity scattering problem for cavity shape, given the scattered solution on the opening of the cavity. This method is a hybrid between an iterative method and an integral equations method for solving the Cauchy problem. The idea of this hybrid method is simple, the operation is easy, and the computation cost is small. Numerical experiments show the feasibility of this method, even for cases with noise.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFC0209700)the National Natural Science Foundation of China(Grant No.41730103)。
文摘Integrated cavity output spectroscopy(ICOS) is an effective technique in trace gase detection.The strong absorption due to the long optical path of this method makes it challenging in the application scenes that have large gas concentration fluctuation,especially when the gas concentration is high.In this paper,we demonstrate an extension of the dynamic range of ICOS by using a detuned laser combined with an off-axis integrating cavity.With this,we improve the upper limit of the dynamic detection range from 0.1%(1000 ppm) to 20% of the gas concentration.This method provides a way of using ICOS in the applications with unpredictable gas concentrations such as gas leak detection,ocean acidification,carbon sequestration,etc.