The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. T...The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.展开更多
Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restric...Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restrictions diversely, how to properly select the specific type among discrete choice models for realistic application still remains to be a tough problem. In this article, five typical discrete choice models for transport mode split are, respectively, discussed, which includes multinomial logit model, nested logit model （NL）, heteroscedastic extreme value model, multinominal probit model and mixed multinomial logit model （MMNL）. The theoretical basis and application attributes of these five models are especially analysed with great attention, and they are also applied to a realistic intercity case of mode split forecast, which results indi- cating that NL model does well in accommodating similarity and heterogeneity across alternatives, while MMNL model serves as the most effective method for mode choice prediction since it shows the highest reliability with the least significant prediction errors and even outperforms the other four models in solving the heterogeneity and similarity problems. This study indicates that conclusions derived from a single discrete choice model are not reliable, and it is better to choose the proper model based on its characteristics.展开更多
Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya-Perot optical cavity via radiation-pressure are investigated by linearized quantum Langevin equation. We work in the resolved s...Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya-Perot optical cavity via radiation-pressure are investigated by linearized quantum Langevin equation. We work in the resolved sideband regime where the oscillator resonance frequency exceeds the cavity linewidth. Normal mode splittings of the mechanical resonator as a pure result of the coupling interaction in the two optomechanical systems is studied, and we make a comparison of normal mode splitting of mechanical resonator between the two systems. In the optical cavity, the normal mode splitting of the movable mirror approaches the latest experiment very well. In addition, an approximation scheme is introduced to demonstrate the ground state cooling, and we make a comparison of cooling between the two systems dominated by two key factors, which are the initial bath temperature and the mechanical quality factor. Since both the normal mode splitting and cooling require working in the resolved sideband regime, whether the normal mode splitting influences the cooling of the mirror is considered. Considering the size of the mechanical resonator and precooling the system, the mechanical resonator in the transmission line resonator system is easier to achieve the ground state cooling than in optical cavity.展开更多
Under a specified loss condition,the resonant mode in a three-turn lossy microfiber coil resonator exhibits periodic evolution among normal resonance,white-light cavity effect,and resonance mode splitting in response ...Under a specified loss condition,the resonant mode in a three-turn lossy microfiber coil resonator exhibits periodic evolution among normal resonance,white-light cavity effect,and resonance mode splitting in response to alterations in the phase shift and coupling state.It exhibits normal resonance when the coupling state exceeds a threshold with specific loss.The white-light cavity effect is activated when the coupling state matches loss.The resonant phase bifurcates as the coupling state falls below the threshold.The excitation conditions for each resonant mode have been derived,and the critical coupling conditions exist for both normal resonance and mode splitting in the case of relatively small losses.展开更多
A novel slotted optical microdisk resonator, which significantly enhances light–matter interaction and provides a promising approach for increasing the sensitivity of sensors, is theoretically and numerically investi...A novel slotted optical microdisk resonator, which significantly enhances light–matter interaction and provides a promising approach for increasing the sensitivity of sensors, is theoretically and numerically investigated. In this slotted resonator, the mode splitting is generated due to reflection of the slot. Remarkably, effects of the slot width and angular position on the mode splitting are mainly studied. The results reveal that the mode splitting is a second function of the slot width, and the maximum mode splitting induced by the slot deformation is achieved with 2.7853 × 10~9Hz∕nm. Therefore, the slotted resonator is an excellent candidate for pressure and force sensing. Besides, the influence of the slot angular position on the mode splitting is a cosine curve with the highest sensitivity of 1.23 × 10^(11)Hz∕deg; thus, the optical characteristic demonstrates that the slotted resonator can be used for inertial measurements.展开更多
An extra-short He-Ne laser (shorter than 100mm) does not work well because there is likely no longitudinal mode in the lasing bandwidth sometimes and the output power rises and falls deeply from time to time.A method ...An extra-short He-Ne laser (shorter than 100mm) does not work well because there is likely no longitudinal mode in the lasing bandwidth sometimes and the output power rises and falls deeply from time to time.A method to solve this problem has been presented and investigated.A piece of quartz crystal plate appropriately designed is used as a cavity mirror of a He-Ne laser,which has a longitudinal mode spacing larger than the lasing bandwidth to make the equal-spacing mode split.In other words,the number of longitudinal modes is doubled and the actual mode spacing is reduced to the half of that without mode split.Therefore,there is always at least one mode operating in the lasing bandwidth and the power is stable at any room temperature.Such a laser with 85mm cavity length and 0.24mW output power has been made.展开更多
The graphene-based double-barrier waveguides induced by electric field have been investigated. The guided modes can only exist in the case of Klein tunneling, and the fundamental mode is absent. The guided modes in th...The graphene-based double-barrier waveguides induced by electric field have been investigated. The guided modes can only exist in the case of Klein tunneling, and the fundamental mode is absent. The guided modes in the single-barrier waveguide split into symmetric and antisymmetric modes with different incident angles in the double-barrier waveguide. The phase difference between electron states and hole states is also discussed. The phase difference for the two splitting modes is close to each other and increases with the order of guided modes. These phenomena can be helpful for the potential applications in graphene-based optoelectronic devices.展开更多
A novel enhancement-mode AlGaN/GaN high electron mobility transistor（HEMT） is proposed and studied.Specifically,several split floating gates（FGs） with negative charges are inserted to the conventional MIS structur...A novel enhancement-mode AlGaN/GaN high electron mobility transistor（HEMT） is proposed and studied.Specifically,several split floating gates（FGs） with negative charges are inserted to the conventional MIS structure.The simulation results revealed that the V_（th） decreases with the increase of polarization sheet charge density and the tunnel dielectric（between FGs and AlGaN） thickness,while it increases with the increase of FGs sheet charge density and blocking dielectric（between FGs and control gate） thickness.In the case of the same gate length,the V_（th） will left shift with decreasing FG length.More interestingly,the split FGs could significantly reduce the device failure probability in comparison with the single large area FG structure.展开更多
The effects of cavity dimensions on the resonance frequency and resonance strength of the TE01δmode in split postdielectric resonator (SPDR) technique are investigated by using full-wave simulations. The results of s...The effects of cavity dimensions on the resonance frequency and resonance strength of the TE01δmode in split postdielectric resonator (SPDR) technique are investigated by using full-wave simulations. The results of simulations provide guidance for adjusting the dimensional parameters of the set-up to ensure that a strong TE01δ resonance mode is excited. The scaled designs of SPDR fixtures for operation at frequencies that are most important for applications are presented. These designs employ two sets of dielectric resonators (DRs) that can be fabricated from the standard ceramic materials. In addition, it is demonstrated that the resonance frequency of the TE01δ mode in the fixture can be tuned by adjusting the gap of the split DR.展开更多
In order to find the main factors that influence the urban traffic structure,a relational model between the travelers＇ characteristics and the trip mode choice is built.The data of urban residents＇ characteristics a...In order to find the main factors that influence the urban traffic structure,a relational model between the travelers＇ characteristics and the trip mode choice is built.The data of urban residents＇ characteristics are obtained from statistical data,while the trip mode split data is collected through a trip survey in Bengbu.In addition,the discrete choice model is adopted to build the functional relationship between the mode choice and the travelers＇ personal characteristics,as well as family characteristics and trip characteristics.The model shows that the relationship between the mode split and the personal,as well as family and trip characteristics is stable and changes little as the time changes.Deduced by the discrete model,the mode split result is relatively accurate and can be feasibly used for trip mode structure forecasts.Furthermore,the proposed model can also contribute to find the key influencing factors on trip mode choice,and restructure or optimize the urban trip mode structure.展开更多
In this study,we selected 18 SG（superconducting gravimeter）records from 15 GGP stations with 99 vertical and 69 horizontal components of IRIS broad-band seismograms during 2004 Sumatra Earthquake to detect the split...In this study,we selected 18 SG（superconducting gravimeter）records from 15 GGP stations with 99 vertical and 69 horizontal components of IRIS broad-band seismograms during 2004 Sumatra Earthquake to detect the splitting of higher-degree Earth’s free oscillations modes（0S4,0S7〈sub〉0S10,2S4,1S5,2S5,1S6）and 12 inner-core sensitive modes（25S2,27S2,6S3,9S3,13S3,15S3,11S4,18S4,8S5,11S5,23S5,16S6）by using OSE（optimal sequence estimation）method which only considers self-coupling.Results indicate that OSE can completely isolate singlets of high-degree modes in time-domain,effectively resolve the coupled multiplets independently,and reduce the possibility of mode mixing and end effect,showing that OSE could improve some signals’signal-to-noise ratio.Comparing the results of SG records with seismic data sets suggests that the number of SG records is inadequate to detect all singlets of higher modes.Hence we mainly selected plentiful seismograms of IRIS to observe the multiplets of higher modes.We estimate frequencies of the singlets using AR method and evaluate the measurement error using bootstrap method.Besides,we compared the observations with the predictions of PREM-tidal model.This study demonstrates that OSE is effective in isolating singlets of Earth’s free oscillations with higher modes.The experimental results may provide constraints to the construction of 3D Earth model.展开更多
在复合功率分流混合动力系统中,通过离合器对功率分流装置与动力部件进行离合和制动,可以进一步提高动力性和经济性。传统湿式离合器为适应商用车大扭矩需求,需增加摩擦片数量和体积,导致成本上升和拖曳损失,而机械式离合器虽体积小、...在复合功率分流混合动力系统中,通过离合器对功率分流装置与动力部件进行离合和制动,可以进一步提高动力性和经济性。传统湿式离合器为适应商用车大扭矩需求,需增加摩擦片数量和体积,导致成本上升和拖曳损失,而机械式离合器虽体积小、承载扭矩大,但在超越过程中产生摩擦损失,无法满足混合动力商用车对可控方向锁止和双向非接触自由的需求。设计了一种多模非接触式可控单向离合器,可实现正向锁止、反向锁止以及双向自由三种模式,承载扭矩大同时避免了拖曳和摩擦损失。对多模非接触式可控单向离合器静态和模式切换过程进行了分析,以提高承载扭矩、减小瞬态冲击和实现轻量设计为目标建立了优化模型,提出融合带精英策略的非支配排序遗传算法(Non-dominated sorting genetic algorithmⅡ,NSGA2)、约束有序加权平均算子(Constrained ordered weighted averaging,COWA)和优劣解距离法(Technique for order preference by similarity to ideal solution,TOPSIS)的多目标优化决策方法,与初始方案相比,承载扭矩提升了23.5%、空转角减少了13.7%、关键部件体积减小了0.5%;搭载混合动力专用变速箱进行了台架试验,验证了设计方法的可行性。研究为大扭矩多模非接触式可控单向离合器的设计提供了参考。展开更多
大地震能够同时激发出许多的地球自由振荡简正模,且地球的椭率、自转和内部的各向异性也会引起简正模的分裂,使各单线态之间的频率更接近(仅为几个μHz),这对地球自由振荡模型的检测提出更高的要求。本文以标准时频变换为基础,推导并验...大地震能够同时激发出许多的地球自由振荡简正模,且地球的椭率、自转和内部的各向异性也会引起简正模的分裂,使各单线态之间的频率更接近(仅为几个μHz),这对地球自由振荡模型的检测提出更高的要求。本文以标准时频变换为基础,推导并验证一种自由振荡模型检测的新方法。以3 S 1模型的检测为例,与经典的FT谱方法和最新的OSE方法相比,该方法具有更高的频率分辨率。展开更多
基金Project supported the National Key Basic Research and Development Program of China (Grant Nos.2012CB921304 and 2013CB632805)the National Natural Science Foundation of China (Grant Nos.60990313,61306120,and 6106003)the Foundation of Fuzhou University (Grant No.022498)
文摘The mode splitting induced by electro-optic birefringence in a P-I-N InGaAs/GaAs/A1GaAs vertical-cavity surface- emitting laser （VCSEL） has been studied by polarized electroluminescence （EL） at room temperature. The polarized EL spectra with E｜｜[110] and E ｜｜ [150] directions, are extracted for different injected currents. The mode splitting of the two orthogonal polarized modes for a VCSEL device is determined, and its value increases linearly with the increasing injected current due to electro-optic birefringence; This article demonstrates that the polarized EL is a powerful tool to study the mode splitting and polarization anisotropy of a VCSEL device.
基金supported by the Science&Technology pillar project(No.0556)of Guangzhou
文摘Discrete choice model acts as one of the most important tools for studies involving mode split in the context of transport demand forecast. As different types of discrete choice models display their merits and restrictions diversely, how to properly select the specific type among discrete choice models for realistic application still remains to be a tough problem. In this article, five typical discrete choice models for transport mode split are, respectively, discussed, which includes multinomial logit model, nested logit model （NL）, heteroscedastic extreme value model, multinominal probit model and mixed multinomial logit model （MMNL）. The theoretical basis and application attributes of these five models are especially analysed with great attention, and they are also applied to a realistic intercity case of mode split forecast, which results indi- cating that NL model does well in accommodating similarity and heterogeneity across alternatives, while MMNL model serves as the most effective method for mode choice prediction since it shows the highest reliability with the least significant prediction errors and even outperforms the other four models in solving the heterogeneity and similarity problems. This study indicates that conclusions derived from a single discrete choice model are not reliable, and it is better to choose the proper model based on its characteristics.
基金supported by the National Natural Science Foundation of China (Grant Nos. 10647132 and 11104113)the Scientific Research Fund of Hunan Provincial Education Department of China (Grant No. 10A100)
文摘Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya-Perot optical cavity via radiation-pressure are investigated by linearized quantum Langevin equation. We work in the resolved sideband regime where the oscillator resonance frequency exceeds the cavity linewidth. Normal mode splittings of the mechanical resonator as a pure result of the coupling interaction in the two optomechanical systems is studied, and we make a comparison of normal mode splitting of mechanical resonator between the two systems. In the optical cavity, the normal mode splitting of the movable mirror approaches the latest experiment very well. In addition, an approximation scheme is introduced to demonstrate the ground state cooling, and we make a comparison of cooling between the two systems dominated by two key factors, which are the initial bath temperature and the mechanical quality factor. Since both the normal mode splitting and cooling require working in the resolved sideband regime, whether the normal mode splitting influences the cooling of the mirror is considered. Considering the size of the mechanical resonator and precooling the system, the mechanical resonator in the transmission line resonator system is easier to achieve the ground state cooling than in optical cavity.
基金supported by the Joint Fund Project(No.8091B042206)the National Natural Science Foundation of China(No.61873064)+2 种基金the National Defense Pre-Research Foundation of China(No.8922006150)the Jiangsu Provincial Key Research and Development Program(No.BE2022139)the Wuxi Key Research and Development Program(No.N20221003)。
文摘Under a specified loss condition,the resonant mode in a three-turn lossy microfiber coil resonator exhibits periodic evolution among normal resonance,white-light cavity effect,and resonance mode splitting in response to alterations in the phase shift and coupling state.It exhibits normal resonance when the coupling state exceeds a threshold with specific loss.The white-light cavity effect is activated when the coupling state matches loss.The resonant phase bifurcates as the coupling state falls below the threshold.The excitation conditions for each resonant mode have been derived,and the critical coupling conditions exist for both normal resonance and mode splitting in the case of relatively small losses.
基金National Natural Science Foundation of China(NSFC)(61575014)Natural Science Foundation of Beijing Municipality(4162038)
文摘A novel slotted optical microdisk resonator, which significantly enhances light–matter interaction and provides a promising approach for increasing the sensitivity of sensors, is theoretically and numerically investigated. In this slotted resonator, the mode splitting is generated due to reflection of the slot. Remarkably, effects of the slot width and angular position on the mode splitting are mainly studied. The results reveal that the mode splitting is a second function of the slot width, and the maximum mode splitting induced by the slot deformation is achieved with 2.7853 × 10~9Hz∕nm. Therefore, the slotted resonator is an excellent candidate for pressure and force sensing. Besides, the influence of the slot angular position on the mode splitting is a cosine curve with the highest sensitivity of 1.23 × 10^(11)Hz∕deg; thus, the optical characteristic demonstrates that the slotted resonator can be used for inertial measurements.
基金Project supported by the Natural Science Foundation of Beijing.
文摘An extra-short He-Ne laser (shorter than 100mm) does not work well because there is likely no longitudinal mode in the lasing bandwidth sometimes and the output power rises and falls deeply from time to time.A method to solve this problem has been presented and investigated.A piece of quartz crystal plate appropriately designed is used as a cavity mirror of a He-Ne laser,which has a longitudinal mode spacing larger than the lasing bandwidth to make the equal-spacing mode split.In other words,the number of longitudinal modes is doubled and the actual mode spacing is reduced to the half of that without mode split.Therefore,there is always at least one mode operating in the lasing bandwidth and the power is stable at any room temperature.Such a laser with 85mm cavity length and 0.24mW output power has been made.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11204170 and 61108010)the Shanghai Municipal Commission of Science and Technology,China(Grant No.16ZR1411600)
文摘The graphene-based double-barrier waveguides induced by electric field have been investigated. The guided modes can only exist in the case of Klein tunneling, and the fundamental mode is absent. The guided modes in the single-barrier waveguide split into symmetric and antisymmetric modes with different incident angles in the double-barrier waveguide. The phase difference between electron states and hole states is also discussed. The phase difference for the two splitting modes is close to each other and increases with the order of guided modes. These phenomena can be helpful for the potential applications in graphene-based optoelectronic devices.
基金Project supported by“Efficient and Energy-Saving GaN on Si Power Devices”Research Fund(Grant No.KQCX20140522151322946)the Research Fund of the Third Generation Semiconductor Key Laboratory of Shenzhen,China(Grant No.ZDSYS20140509142721434)+1 种基金the“Key Technology Research of GaN on Si Power Devices”Research Fund(Grant No.JSGG20140729145956266)the“Research of Low Cost Fabrication of GaN Power Devices and System Integration”Research Fund(Grant No.JCYJ201602261926390)
文摘A novel enhancement-mode AlGaN/GaN high electron mobility transistor（HEMT） is proposed and studied.Specifically,several split floating gates（FGs） with negative charges are inserted to the conventional MIS structure.The simulation results revealed that the V_（th） decreases with the increase of polarization sheet charge density and the tunnel dielectric（between FGs and AlGaN） thickness,while it increases with the increase of FGs sheet charge density and blocking dielectric（between FGs and control gate） thickness.In the case of the same gate length,the V_（th） will left shift with decreasing FG length.More interestingly,the split FGs could significantly reduce the device failure probability in comparison with the single large area FG structure.
文摘The effects of cavity dimensions on the resonance frequency and resonance strength of the TE01δmode in split postdielectric resonator (SPDR) technique are investigated by using full-wave simulations. The results of simulations provide guidance for adjusting the dimensional parameters of the set-up to ensure that a strong TE01δ resonance mode is excited. The scaled designs of SPDR fixtures for operation at frequencies that are most important for applications are presented. These designs employ two sets of dielectric resonators (DRs) that can be fabricated from the standard ceramic materials. In addition, it is demonstrated that the resonance frequency of the TE01δ mode in the fixture can be tuned by adjusting the gap of the split DR.
基金The National Natural Science Foundation of China (No.50738001,51078086)
文摘In order to find the main factors that influence the urban traffic structure,a relational model between the travelers＇ characteristics and the trip mode choice is built.The data of urban residents＇ characteristics are obtained from statistical data,while the trip mode split data is collected through a trip survey in Bengbu.In addition,the discrete choice model is adopted to build the functional relationship between the mode choice and the travelers＇ personal characteristics,as well as family characteristics and trip characteristics.The model shows that the relationship between the mode split and the personal,as well as family and trip characteristics is stable and changes little as the time changes.Deduced by the discrete model,the mode split result is relatively accurate and can be feasibly used for trip mode structure forecasts.Furthermore,the proposed model can also contribute to find the key influencing factors on trip mode choice,and restructure or optimize the urban trip mode structure.
基金supported by the National 973 Project of China (No.2013CB733305)the NSFC (Nos.41174011,41429401,41574007,41210006,41128003,41021061)
文摘In this study,we selected 18 SG（superconducting gravimeter）records from 15 GGP stations with 99 vertical and 69 horizontal components of IRIS broad-band seismograms during 2004 Sumatra Earthquake to detect the splitting of higher-degree Earth’s free oscillations modes（0S4,0S7〈sub〉0S10,2S4,1S5,2S5,1S6）and 12 inner-core sensitive modes（25S2,27S2,6S3,9S3,13S3,15S3,11S4,18S4,8S5,11S5,23S5,16S6）by using OSE（optimal sequence estimation）method which only considers self-coupling.Results indicate that OSE can completely isolate singlets of high-degree modes in time-domain,effectively resolve the coupled multiplets independently,and reduce the possibility of mode mixing and end effect,showing that OSE could improve some signals’signal-to-noise ratio.Comparing the results of SG records with seismic data sets suggests that the number of SG records is inadequate to detect all singlets of higher modes.Hence we mainly selected plentiful seismograms of IRIS to observe the multiplets of higher modes.We estimate frequencies of the singlets using AR method and evaluate the measurement error using bootstrap method.Besides,we compared the observations with the predictions of PREM-tidal model.This study demonstrates that OSE is effective in isolating singlets of Earth’s free oscillations with higher modes.The experimental results may provide constraints to the construction of 3D Earth model.
文摘在复合功率分流混合动力系统中,通过离合器对功率分流装置与动力部件进行离合和制动,可以进一步提高动力性和经济性。传统湿式离合器为适应商用车大扭矩需求,需增加摩擦片数量和体积,导致成本上升和拖曳损失,而机械式离合器虽体积小、承载扭矩大,但在超越过程中产生摩擦损失,无法满足混合动力商用车对可控方向锁止和双向非接触自由的需求。设计了一种多模非接触式可控单向离合器,可实现正向锁止、反向锁止以及双向自由三种模式,承载扭矩大同时避免了拖曳和摩擦损失。对多模非接触式可控单向离合器静态和模式切换过程进行了分析,以提高承载扭矩、减小瞬态冲击和实现轻量设计为目标建立了优化模型,提出融合带精英策略的非支配排序遗传算法(Non-dominated sorting genetic algorithmⅡ,NSGA2)、约束有序加权平均算子(Constrained ordered weighted averaging,COWA)和优劣解距离法(Technique for order preference by similarity to ideal solution,TOPSIS)的多目标优化决策方法,与初始方案相比,承载扭矩提升了23.5%、空转角减少了13.7%、关键部件体积减小了0.5%;搭载混合动力专用变速箱进行了台架试验,验证了设计方法的可行性。研究为大扭矩多模非接触式可控单向离合器的设计提供了参考。
文摘大地震能够同时激发出许多的地球自由振荡简正模,且地球的椭率、自转和内部的各向异性也会引起简正模的分裂,使各单线态之间的频率更接近(仅为几个μHz),这对地球自由振荡模型的检测提出更高的要求。本文以标准时频变换为基础,推导并验证一种自由振荡模型检测的新方法。以3 S 1模型的检测为例,与经典的FT谱方法和最新的OSE方法相比,该方法具有更高的频率分辨率。
