A wavelet-based method was developed to compute elastic band gaps of one-dimensional phononic crystals. The wave field was expanded in the wavelet basis and an equivalent eigenvalue problem was derived in a matrix for...A wavelet-based method was developed to compute elastic band gaps of one-dimensional phononic crystals. The wave field was expanded in the wavelet basis and an equivalent eigenvalue problem was derived in a matrix form involving the adaptive computation of integrals of the wavelets. The method was then applied to a binary system. For comparison, the elastic band gaps of the same one-dimensional phononic crystals computed with the wavelet method and the well- known plane wave expansion (PWE) method are both presented in this paper. The numerical results of the two methods are in good agreement while the computation costs of the wavelet method are much lower than that of PWE method. In addition, the adaptability of wavelets makes the method possible for efficient band gap computation of more complex phononic structures.展开更多
In the present paper, we study the transmission of the two-dimensional photonic crystal （PC） superellipse ring resonator. The fast growing applications of optomechanical systems lead to strong demands in new sensing...In the present paper, we study the transmission of the two-dimensional photonic crystal （PC） superellipse ring resonator. The fast growing applications of optomechanical systems lead to strong demands in new sensing mechanism in order to design the sensing elements to nanometer scale. The photonic crystal based resonator has been investigated as promising solutions because the band gap structure and resonator characteristics are extremely sensitive to the deformation and position shift of rod/cavity in PC resonators. This structure opens a single channel filter. The study is extended for tuning of channel filter＇s wavelength with a temperature of this structure. The transmission of the channel filter shows a red shift with temperature linearly. This wavelength shift of the channel filter is used for the sensor application. The sensitivity for the proposed structure is found to be 65.3pm/℃. The outstanding sensing capability renders PC resonators as a promising optomechanical sensing element to be integrated into various transducers for temperature sensing applications.展开更多
Using the plane-wave expansion (PWE)method , the band gaps of the two-dimension phononic crystals composed of square, triangle and honeycomb arrays aluminum cylinders in the air are calculated numerically. The band st...Using the plane-wave expansion (PWE)method , the band gaps of the two-dimension phononic crystals composed of square, triangle and honeycomb arrays aluminum cylinders in the air are calculated numerically. The band structures of three lattices were compared and analyzed. It is concluded that the band-gap of honeycomb lattices is located at lower frequency fields, compared with square and triangle lattices. When the filling fraction is between 0.091 and 0.6046, the honeycomb lattices have larger band gaps and gain an advantage over square and triangle lattices. In addition, the gap map is introduced to illustrate the influences of filling fraction on the number, the relative width and the limit frequency of the band-gap.展开更多
We propose to measure the concentration of potassium chloride using photonic crystal fiber having circular air holes of diameter 400 nm. The principle of measurement is based on the linear variation of the transmitted...We propose to measure the concentration of potassium chloride using photonic crystal fiber having circular air holes of diameter 400 nm. The principle of measurement is based on the linear variation of the transmitted field emerging from the PCF with respect to concentration of potassium chloride. Field distribution in photonic crystal structure is simulated using plane wave expansion (PWE) method. Simulation result reveals that the intensity of transmitted light varies linearly with respect to concentration of potassium chloride filled in the air holes.展开更多
A two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based Bandpass Filter (BPF) is designed to cover C and L+U bands of Coarse Wavelength Division Multiplexing (CWDM) systems. It is devised with two quasi wa...A two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based Bandpass Filter (BPF) is designed to cover C and L+U bands of Coarse Wavelength Division Multiplexing (CWDM) systems. It is devised with two quasi waveguides and a circular PCRR. The simulation results are obtained using 2D Finite Difference Time Domain (FDTD) method. The Photonic Band Gap (PBG) is calculated by Plane Wave Expansion (PWE) method. The BPFs allow the entire C-band (BPF1) and L+U bands (BPF2), which are extended from 1530 to 1565 nm (C band) and 1565 to 1675 nm (L+U bands). The computed bandwidth of BPF1 and BPF2 is 32 nm and 97 nm respectively. The size of the device is minimized from a scale of few tens of millimeters to the order of micrometers. The overall size of the BPF1 is around 12.8 μm × 11.4 μm and 11.4 μm × 11.4 μm for BPF2.展开更多
The factors affecting one dimensional （1D） and two dimensional （2D） photonic crystals （PhCs） are systemically analyzed in this paper by numerical simulation. Transfer matrix method （TMM） is employed for 1D PCs...The factors affecting one dimensional （1D） and two dimensional （2D） photonic crystals （PhCs） are systemically analyzed in this paper by numerical simulation. Transfer matrix method （TMM） is employed for 1D PCs, both finite difference time domain method （FDTD） and plane wave expansion method （PWE） are employed for 2D PCs. The result shows that the photonic bandgaps （PBG） are directly affected by crystal type, crystal lattice constant, modulation of refractive index and periodicity, and it is should be useful for design of different type photonic crystals with the required PBG and functional devices. Finally, as an example, a near-IR 1D PCs narrow filter was designed.展开更多
The overall transmitted efficiency at 1550 nm for Nylon-Teflon/Teflon-Nylon （N-T/T-N） grating Silicon- on-insulator （SOI） structure with defect in even and odd position was investigated in this paper. Different ty...The overall transmitted efficiency at 1550 nm for Nylon-Teflon/Teflon-Nylon （N-T/T-N） grating Silicon- on-insulator （SOI） structure with defect in even and odd position was investigated in this paper. Different types of losses, such as absorption, reflection and diffraction, were considered to find out the overall transmitted efficiency. The absorption loss of both Nylon-Teflon （N-T） and Teflon-Nylon （T-N） structure is zero at the wavelength of 1550 nm. Reflectance of these structures was analyzed by using plane wave expansion （PWE） method. Simulation result showed that reflectance as well as transmittance was varied linearly with respect to defect at odd and even positions. Simulation is also done for the diffraction efficiency at 1550nm with respect to detuning from Bragg＇s angle, which was ranged from -0.4 rad to ＋ 0.4 rad. Finally, it was found that overall transmitted efficiency increased as even defect position varied from 2nd to 10th for both N-T/T-N grating SOI structure. Similarly, the overall transmitted efficiency decreased as odd defect position changed from 3rd to l lth for both N-T/T-N grating SOI structure.展开更多
The plane-wave expansion(PWE) method is employed to calculate the photonic band structures of metal/dielectric(M/D) periodic systems. We consider a one-dimensional(1D) M/D superlattice with a metal layer characterized...The plane-wave expansion(PWE) method is employed to calculate the photonic band structures of metal/dielectric(M/D) periodic systems. We consider a one-dimensional(1D) M/D superlattice with a metal layer characterized by a frequency-dependent dielectric function. To calculate the photonic band of such a system, we propose a new method and thus avoid solving the nonlinear eigenvalue equations. We obtained the frequency dispersions and the energy distributions of eigen-modes of 1D superlattices. This general method is applicable to calculate the photonic band of a broad class of physical systems, e.g. 2D and 3D M/D photonic crystals. For comparison, we present a simple introduction of the finite-difference(FD) method to calculate the same system, and the agreement turns out to be good. But the FD method cannot be applied to the TM modes of the M/D superlattice.展开更多
Background Although epilepsy has been acknowledged as an illness since ancient time,the public attitude toward epilepsy has not changed drastically due to the lack of appropriate information.This study aims to determi...Background Although epilepsy has been acknowledged as an illness since ancient time,the public attitude toward epilepsy has not changed drastically due to the lack of appropriate information.This study aims to determine the public perceptions of epilepsy in five main regions of Saudi Arabia.Methods In this cross-sectional questionnaire-based study,Saudi citizens living in the major cities of the five main regions of the Kingdom of Saudi Arabia(the central,eastern,western,northern,and southern regions)completed the survey that included 27 questions about epilepsy awareness.Results A total of 7118 individuals from five regions participated in the survey:6749(94.8%)of respondents were Saudi,and 369(5.2%)were non-Saudi.Of the 7118 respondents,6897 respondents(96.9%)did not have epilepsy,and 3378 respondents(47.5%)stated that they had never witnessed an epileptic episode.In addition,3749(52.7%)respondents incorrectly attributed epilepsy to non-neurologic conditions,and 4865(68.3%)respondents had an overall negative attitude toward people with epilepsy(PWE).They expressed objections to their child associating with PWE(2002;28.1%)or their close relatives marrying PWE(3192;44.8%),some believed that PWE are inferior(402;5.6%),refused to hire a PWE(1126;15.8%),and would feel discomfort around PWE(724;10.3%).In addition,2025 individuals(28.4%)believed that the health of PWE deteriorates over time;1485 individuals(20.9%)believed that PWE get sick more often than others;181 individuals(2.5%)believed that epilepsy could be transmitted;and 568 individuals(8.0%)believed that epilepsy could progress to malignant disease.Conclusions In Saudi Arabia,there is a substantial need for increasing the awareness and improving education on epilepsy in order to reduce stigma and increase the understanding of epilepsy.Such efforts could help improve the lives of people afflicted with the disease and ultimately contribute to better health outcomes for the entire community.展开更多
针对指挥控制组织结构设计中任务—平台关系的设计问题,提出了一种使命完成时间限制条件下的问题的设计模型及其求解算法。分析了使命完成时间限制条件下任务—平台关系设计(task-platform relation de-sign under mission completion t...针对指挥控制组织结构设计中任务—平台关系的设计问题,提出了一种使命完成时间限制条件下的问题的设计模型及其求解算法。分析了使命完成时间限制条件下任务—平台关系设计(task-platform relation de-sign under mission completion time constraint,TPRDTC)问题的约束条件,建立了以使命执行质量的值最大为目标的问题数学模型。设计了用于求解该模型的循环多动态列表规划(multi-dimensional dynamic list scheduling,MDLS)算法,给出了该算法的详细步骤和流程。最后通过一个联合作战的战役案例,分析并验证了循环MDLS算法对求解TPRDTC问题的有效性和适用性。展开更多
基金Supported by the National Natural Science Foundation of China (Grant No. 10632020)
文摘A wavelet-based method was developed to compute elastic band gaps of one-dimensional phononic crystals. The wave field was expanded in the wavelet basis and an equivalent eigenvalue problem was derived in a matrix form involving the adaptive computation of integrals of the wavelets. The method was then applied to a binary system. For comparison, the elastic band gaps of the same one-dimensional phononic crystals computed with the wavelet method and the well- known plane wave expansion (PWE) method are both presented in this paper. The numerical results of the two methods are in good agreement while the computation costs of the wavelet method are much lower than that of PWE method. In addition, the adaptability of wavelets makes the method possible for efficient band gap computation of more complex phononic structures.
文摘In the present paper, we study the transmission of the two-dimensional photonic crystal （PC） superellipse ring resonator. The fast growing applications of optomechanical systems lead to strong demands in new sensing mechanism in order to design the sensing elements to nanometer scale. The photonic crystal based resonator has been investigated as promising solutions because the band gap structure and resonator characteristics are extremely sensitive to the deformation and position shift of rod/cavity in PC resonators. This structure opens a single channel filter. The study is extended for tuning of channel filter＇s wavelength with a temperature of this structure. The transmission of the channel filter shows a red shift with temperature linearly. This wavelength shift of the channel filter is used for the sensor application. The sensitivity for the proposed structure is found to be 65.3pm/℃. The outstanding sensing capability renders PC resonators as a promising optomechanical sensing element to be integrated into various transducers for temperature sensing applications.
文摘Using the plane-wave expansion (PWE)method , the band gaps of the two-dimension phononic crystals composed of square, triangle and honeycomb arrays aluminum cylinders in the air are calculated numerically. The band structures of three lattices were compared and analyzed. It is concluded that the band-gap of honeycomb lattices is located at lower frequency fields, compared with square and triangle lattices. When the filling fraction is between 0.091 and 0.6046, the honeycomb lattices have larger band gaps and gain an advantage over square and triangle lattices. In addition, the gap map is introduced to illustrate the influences of filling fraction on the number, the relative width and the limit frequency of the band-gap.
文摘We propose to measure the concentration of potassium chloride using photonic crystal fiber having circular air holes of diameter 400 nm. The principle of measurement is based on the linear variation of the transmitted field emerging from the PCF with respect to concentration of potassium chloride. Field distribution in photonic crystal structure is simulated using plane wave expansion (PWE) method. Simulation result reveals that the intensity of transmitted light varies linearly with respect to concentration of potassium chloride filled in the air holes.
文摘A two Dimensional (2D) Photonic Crystal Ring Resonator (PCRR) based Bandpass Filter (BPF) is designed to cover C and L+U bands of Coarse Wavelength Division Multiplexing (CWDM) systems. It is devised with two quasi waveguides and a circular PCRR. The simulation results are obtained using 2D Finite Difference Time Domain (FDTD) method. The Photonic Band Gap (PBG) is calculated by Plane Wave Expansion (PWE) method. The BPFs allow the entire C-band (BPF1) and L+U bands (BPF2), which are extended from 1530 to 1565 nm (C band) and 1565 to 1675 nm (L+U bands). The computed bandwidth of BPF1 and BPF2 is 32 nm and 97 nm respectively. The size of the device is minimized from a scale of few tens of millimeters to the order of micrometers. The overall size of the BPF1 is around 12.8 μm × 11.4 μm and 11.4 μm × 11.4 μm for BPF2.
基金Sponsored by the Ministerial Level Advanced Research Foundation (1006513002060)
文摘The factors affecting one dimensional （1D） and two dimensional （2D） photonic crystals （PhCs） are systemically analyzed in this paper by numerical simulation. Transfer matrix method （TMM） is employed for 1D PCs, both finite difference time domain method （FDTD） and plane wave expansion method （PWE） are employed for 2D PCs. The result shows that the photonic bandgaps （PBG） are directly affected by crystal type, crystal lattice constant, modulation of refractive index and periodicity, and it is should be useful for design of different type photonic crystals with the required PBG and functional devices. Finally, as an example, a near-IR 1D PCs narrow filter was designed.
文摘The overall transmitted efficiency at 1550 nm for Nylon-Teflon/Teflon-Nylon （N-T/T-N） grating Silicon- on-insulator （SOI） structure with defect in even and odd position was investigated in this paper. Different types of losses, such as absorption, reflection and diffraction, were considered to find out the overall transmitted efficiency. The absorption loss of both Nylon-Teflon （N-T） and Teflon-Nylon （T-N） structure is zero at the wavelength of 1550 nm. Reflectance of these structures was analyzed by using plane wave expansion （PWE） method. Simulation result showed that reflectance as well as transmittance was varied linearly with respect to defect at odd and even positions. Simulation is also done for the diffraction efficiency at 1550nm with respect to detuning from Bragg＇s angle, which was ranged from -0.4 rad to ＋ 0.4 rad. Finally, it was found that overall transmitted efficiency increased as even defect position varied from 2nd to 10th for both N-T/T-N grating SOI structure. Similarly, the overall transmitted efficiency decreased as odd defect position changed from 3rd to l lth for both N-T/T-N grating SOI structure.
基金supported by the special funds for the National Basic Research Program of China(Grant No.069c031001)the National Natural Science Foundation of China(Grant No.60521001).
文摘The plane-wave expansion(PWE) method is employed to calculate the photonic band structures of metal/dielectric(M/D) periodic systems. We consider a one-dimensional(1D) M/D superlattice with a metal layer characterized by a frequency-dependent dielectric function. To calculate the photonic band of such a system, we propose a new method and thus avoid solving the nonlinear eigenvalue equations. We obtained the frequency dispersions and the energy distributions of eigen-modes of 1D superlattices. This general method is applicable to calculate the photonic band of a broad class of physical systems, e.g. 2D and 3D M/D photonic crystals. For comparison, we present a simple introduction of the finite-difference(FD) method to calculate the same system, and the agreement turns out to be good. But the FD method cannot be applied to the TM modes of the M/D superlattice.
文摘Background Although epilepsy has been acknowledged as an illness since ancient time,the public attitude toward epilepsy has not changed drastically due to the lack of appropriate information.This study aims to determine the public perceptions of epilepsy in five main regions of Saudi Arabia.Methods In this cross-sectional questionnaire-based study,Saudi citizens living in the major cities of the five main regions of the Kingdom of Saudi Arabia(the central,eastern,western,northern,and southern regions)completed the survey that included 27 questions about epilepsy awareness.Results A total of 7118 individuals from five regions participated in the survey:6749(94.8%)of respondents were Saudi,and 369(5.2%)were non-Saudi.Of the 7118 respondents,6897 respondents(96.9%)did not have epilepsy,and 3378 respondents(47.5%)stated that they had never witnessed an epileptic episode.In addition,3749(52.7%)respondents incorrectly attributed epilepsy to non-neurologic conditions,and 4865(68.3%)respondents had an overall negative attitude toward people with epilepsy(PWE).They expressed objections to their child associating with PWE(2002;28.1%)or their close relatives marrying PWE(3192;44.8%),some believed that PWE are inferior(402;5.6%),refused to hire a PWE(1126;15.8%),and would feel discomfort around PWE(724;10.3%).In addition,2025 individuals(28.4%)believed that the health of PWE deteriorates over time;1485 individuals(20.9%)believed that PWE get sick more often than others;181 individuals(2.5%)believed that epilepsy could be transmitted;and 568 individuals(8.0%)believed that epilepsy could progress to malignant disease.Conclusions In Saudi Arabia,there is a substantial need for increasing the awareness and improving education on epilepsy in order to reduce stigma and increase the understanding of epilepsy.Such efforts could help improve the lives of people afflicted with the disease and ultimately contribute to better health outcomes for the entire community.
文摘针对指挥控制组织结构设计中任务—平台关系的设计问题,提出了一种使命完成时间限制条件下的问题的设计模型及其求解算法。分析了使命完成时间限制条件下任务—平台关系设计(task-platform relation de-sign under mission completion time constraint,TPRDTC)问题的约束条件,建立了以使命执行质量的值最大为目标的问题数学模型。设计了用于求解该模型的循环多动态列表规划(multi-dimensional dynamic list scheduling,MDLS)算法,给出了该算法的详细步骤和流程。最后通过一个联合作战的战役案例,分析并验证了循环MDLS算法对求解TPRDTC问题的有效性和适用性。
