Electro-optical/infrared (EO/IR) sensors and photovoltaic power sources are being developed for a variety of defense and commercial applications. One of the critical technologies that will enhance both EO/IR sensor an...Electro-optical/infrared (EO/IR) sensors and photovoltaic power sources are being developed for a variety of defense and commercial applications. One of the critical technologies that will enhance both EO/IR sensor and photovoltaic module performance is the development of high quality nanostructure-based antireflection coatings. In this paper, we review our work on advanced antireflection structures that have been designed by using a genetic algorithm and fabricated by using oblique angle deposition. The antireflection coatings are designed for the wavelength range of 250 nm to 2500 nm and an incidence angle between 00 and 400. These nanostructured antireflection coatings are shown to enhance the optical transmission through transparent windows over a wide band of interest and minimize broadband reflection losses to less than one percent, a substantial improvement over conventional thin-film antireflection coating technologies.展开更多
We review recent work on narrowband orthogonally polarized optical RF single sideband generators as well as dualchannel equalization,both based on high-Q integrated ring resonators.The devices operate in the optical t...We review recent work on narrowband orthogonally polarized optical RF single sideband generators as well as dualchannel equalization,both based on high-Q integrated ring resonators.The devices operate in the optical telecommunications C-band and enable RF operation over a range of either fixed or thermally tuneable frequencies.They operate via TE/TM mode birefringence in the resonator.We achieve a very large dynamic tuning range of over 55 dB for both the optical carrier-to-sideband ratio and the dual-channel RF equalization for both the fixed and tunable devices.展开更多
In time division synchronous code division multiple access （TD-SCDMA） wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The...In time division synchronous code division multiple access （TD-SCDMA） wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The performance of such systems is affected by the phase noise of the microwave local oscillator. The phase noise model of synthesizer and the RF transceiver model for the phase noise effect are proposed for applications of TD-SCDMA systems. The relationship between the power spectral density （PSD） and root mean square （RMS） phase error is given. Then, the error vector magnitude （EVM） performance is analytically evaluated by using the single side band （SSB） phase noise. Theoretical results show agreement with those obtained by measurement data and therefore can be used to derive the TD-SCDMA system performance.展开更多
We propose a novel hybrid phase-locked loop （PLL） architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a...We propose a novel hybrid phase-locked loop （PLL） architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator （VCO） and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor （CMOS） process with a total die area of 1.4×0.46 mm2. The measured results exhibit a reference spur level of lower than -73 dB with a reference frequency of 10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V.展开更多
In this paper, we demonstrate six types of metamaterial absorbers （MMAs） by measuring their absorptivities in an X-band （8 12 GHz） rectangular waveguide. Some of the MMAs have been demonstrated previously by using...In this paper, we demonstrate six types of metamaterial absorbers （MMAs） by measuring their absorptivities in an X-band （8 12 GHz） rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.展开更多
One example of an artificial intelligence ethical dilemma is the autonomous vehicle situation presented by Massachusetts Institute of Technology researchers in the Moral Machine Experiment.To solve such dilemmas,the M...One example of an artificial intelligence ethical dilemma is the autonomous vehicle situation presented by Massachusetts Institute of Technology researchers in the Moral Machine Experiment.To solve such dilemmas,the MIT researchers used a classic statistical method known as the hierarchical Bayesian(HB)model.This paper builds upon previous work for modeling moral decision making,applies a deep learning method to learn human ethics in this context,and compares it to the HB approach.These methods were tested to predict moral decisions of simulated populations of Moral Machine participants.Overall,test results indicate that deep neural networks can be effective in learning the group morality of a population through observation,and outperform the Bayesian model in the cases of model mismatches.展开更多
Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject t...Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject to minimization of the channel blocking and provisional requests satisfying the limits due to accumulative linear dispersion effects over the hops. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the Generalized Multiprotocol Label Switching (GMPLS) environment. The GMPLS framework can offer an approach to implement IP over DWDM with variable weighting assignments of routes based on the limitations due to residual dispersion accumulated on the lightwave path. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated based mainly on a long-haul terrestrial fiber mesh network composed of as well as three topologies structured as chain, ring, and mesh configurations. Blocking probability of lightpath connection requests are examined with the average link utilization in the network employing variable number of wavelength channels in association with the limits of route distance due to linear chromatic and polarization mode dispersion effects.展开更多
We propose and experimentally demonstrate the operation of an electrically tunable, broadband coherent perfect absorption(CPA) at microwave frequencies by harnessing the CPA features of a graphene–electrolyte–graphe...We propose and experimentally demonstrate the operation of an electrically tunable, broadband coherent perfect absorption(CPA) at microwave frequencies by harnessing the CPA features of a graphene–electrolyte–graphene sandwich structure(GSS). Using both a simplified lumped circuit model and full-wave numerical simulation, it is found that the microwave coherent absorptivity of the GSS can be tuned dynamically from nearly 50% to 100% by changing the Fermi level of the graphene. Strikingly, our simplified lumped circuit model agrees very well with the full-wave numerical model, offering valuable insight into the CPA operation of the device. The angle dependency of coherent absorption in the GSS is further investigated, making suggestions for achieving CPA at wide angles up to 80°. To show the validity and accuracy of our theory and numerical simulations, a GSS prototype is fabricated and measured in a C-band waveguide system. The reasonably good agreement between the experimental and the simulated results confirms that the tunable coherent absorption in GSS can be electrically controlled by changing the Fermi level of the graphene.展开更多
We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters,with microcombs having channel spacings of 200 and 49 GHz.Th...We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters,with microcombs having channel spacings of 200 and 49 GHz.This approach to realizing RF channelizers offers reduced complexity,size,and potential cost for a wide range of applications to microwave signal detection.展开更多
目的:建立和验证一个涉及多级临床场景的白内障协作通用的人工智能(artificial intelligence,AI)管理平台,探索基于AI的医疗转诊模式,以提高协作效率和资源覆盖率。方法:训练和验证的数据集来自中国AI医学联盟,涵盖多级医疗机构和采集...目的:建立和验证一个涉及多级临床场景的白内障协作通用的人工智能(artificial intelligence,AI)管理平台,探索基于AI的医疗转诊模式,以提高协作效率和资源覆盖率。方法:训练和验证的数据集来自中国AI医学联盟,涵盖多级医疗机构和采集模式。使用三步策略对数据集进行标记:1)识别采集模式;2)白内障诊断包括正常晶体眼、白内障眼或白内障术后眼;3)从病因和严重程度检测需转诊的白内障患者。此外,将白内障AI系统与真实世界中的居家自我监测、初级医疗保健机构和专科医院等多级转诊模式相结合。结果:通用AI平台和多级协作模式在三步任务中表现出可靠的诊断性能:1)识别采集模式的受试者操作特征(receiver operating characteristic curve,ROC)曲线下面积(area under the curve,AUC)为99.28%~99.71%);2)白内障诊断对正常晶体眼、白内障或术后眼,在散瞳-裂隙灯模式下的AUC分别为99.82%、99.96%和99.93%,其他采集模式的AUC均>99%;3)需转诊白内障的检测(在所有测试中AUC>91%)。在真实世界的三级转诊模式中,该系统建议30.3%的人转诊,与传统模式相比,眼科医生与人群服务比率大幅提高了10.2倍。结论:通用AI平台和多级协作模式显示了准确的白内障诊断性能和有效的白内障转诊服务。建议AI的医疗转诊模式扩展应用到其他常见疾病和资源密集型情景当中。展开更多
Traditional analytical approaches for stability assessment of inverter-based resources(IBRs),often requiring detailed knowledge of IBR internals,become impractical due to IBRs’proprietary nature.Admittance measuremen...Traditional analytical approaches for stability assessment of inverter-based resources(IBRs),often requiring detailed knowledge of IBR internals,become impractical due to IBRs’proprietary nature.Admittance measurements,relying on electromagnetic transient simulation or laboratory settings,are not only time-intensive but also operationally inflexible,since various non-linear control loops make IBRs’admittance models operating-point dependent.Therefore,such admittance measurements must be performed repeatedly when operating point changes.To avoid time-consuming and cumbersome measurements,admittance estimation for arbitrary operating points is highly desirable.However,existing admittance estimation algorithms usually face challenges in versatility,data demands,and accuracy.Addressing this challenge,this letter presents a simple and efficient admittance estimation method for blackboxed IBRs,by utilizing a minimal set of seven operating points to solve a homogeneous linear equation system.Case studies demonstrate this proposed method ensures high accuracy across various types of IBRs.Estimation accuracy is satisfying even when non-negligible measurement errors exist.展开更多
Liberalized electricity markets,smart grids and high penetration of renewable energy sources(RESs)led to the development of novel markets,whose objective is the harmonization between production and demand,usually note...Liberalized electricity markets,smart grids and high penetration of renewable energy sources(RESs)led to the development of novel markets,whose objective is the harmonization between production and demand,usually noted as real time of flexibility markets.This necessitates the development of novel pricing schemes able to allow energy service providers(ESPs)to maximize their aggregated profits from the traditional markets(trading between wholesale/day-ahead and retail markets)and the innovative flexibility markets.In the same time,ESPs have to offer their end users(consumers)competitive(low cost)energy services.In this context,novel pricing schemes must act,among others,as automated demand side management(DSM)techniques that are able to trigger the desired behavioral changes according to the flexibility market prices in energy consumption curves(ECCs)of the consumers.Energy pricing schemes proposed so far,e.g.realtime pricing,interact in an efficient way with wholesale market.But they do not provide consumers with strong enough financial incentives to modify their energy consumption habits towards energy cost curtailment.Thus,they do not interact efficiently with flexibility markets.Therefore,we develop a flexibility real-time pricing(FRTP)scheme,which offers a dynamically adjustable level of financial incentives to participating users by fairly rewarding the ones that make desirable behavioral changes in their ECCs.Performance evaluation results demonstrate that the proposed FRTP is able to offer a 15%–30%more attractive trade-off between the stacked profits of ESPs,i.e.the sum of the profits from retail and flexibility markets,and the satisfaction of consumers.展开更多
Matryoshka-caged gold nanorods （mCGNRs） were successfully synthesized by alternating between a seed-mediated silver-coating method and galvanic replacement reactions （GRRs）. As the number of matryoshka layers of t...Matryoshka-caged gold nanorods （mCGNRs） were successfully synthesized by alternating between a seed-mediated silver-coating method and galvanic replacement reactions （GRRs）. As the number of matryoshka layers of the mCGNRs increased, the plasmon resonance peak broadened and was red-shifted, and the catalytic activity towards the reduction of 4-nitrophenol （4-NTP） increased. When mCGNRs with 6 layers were used as nanocatalysts in the reduction of 4-nitrophenol, the reaction rate coefficient was 5.2- and 3.7-times higher than that of the gold-nanorod- and caged-gold-nanorod-catalyzed reductions of 4-nitrophenol, respectively. In addition, the surface-plasmon-resonance-based absorption of light enhanced the catalytic performance of the mCGNRs. With the support of a polyurethane foam, the mCGNRs synthesized in this study can be applied as recydable heterogeneous catalysts for the reduction of 4-nitrophenol.展开更多
The era of artificial intelligence and internet of things is rapidly developed by recent advances in wearable electronics.Gait reveals sensory information in daily life containing personal information,regarding identi...The era of artificial intelligence and internet of things is rapidly developed by recent advances in wearable electronics.Gait reveals sensory information in daily life containing personal information,regarding identification and healthcare.Current wearable electronics of gait analysis are mainly limited by high fabrication cost,operation energy consumption,or inferior analysis methods,which barely involve machine learning or implement nonoptimal models that require massive datasets for training.Herein,we developed low-cost triboelectric intelligent socks for harvesting waste energy from low-frequency body motions to transmit wireless sensory data.The sock equipped with self-powered functionality also can be used as wearable sensors to deliver information,regarding the identity,health status,and activity of the users.To further address the issue of ineffective analysis methods,an optimized deep learning model with an end-to-end structure on the socks signals for the gait analysis is proposed,which produces a 93.54%identification accuracy of 13 participants and detects five different human activities with 96.67%accuracy.Toward practical application,we map the physical signals collected through the socks in the virtual space to establish a digital human system for sports monitoring,healthcare,identification,and future smart home applications.展开更多
We experimentally demonstrate a scheme to deterministically excite a three-dimensionally oriented electric dipole in a single Au nanosphere by using a tightly focused radially polarized beam whose focal field possesse...We experimentally demonstrate a scheme to deterministically excite a three-dimensionally oriented electric dipole in a single Au nanosphere by using a tightly focused radially polarized beam whose focal field possesses polarization states along three-dimensional(3D) orientations owing to the spatial overlap between longitudinal and radial electric field components. Experiment observations indicate that the orientation of an excited dipole moment gradually changes from out-of-plane to in-plane when the nanosphere is moved away from the beam center, which is reconfirmed by full-wave simulations. Moreover, rigorous calculation based on Mie theory reveals that a reduced effective ambient permittivity accompanies the rotation of the dipole moment, leading to a blue-shifted and narrowed resonance peak. We envision that our results could find applications in detecting the 3D orientation of isolated molecules and benefit the fine manipulation of light–matter interactions at the single-molecule level.展开更多
Selecting a cost optimum subset of discrete-value dispersion compensation modules (DV-DCMs) subject to maximum module count from an available set of DV-DCMs is a NP-hard problem. We derive a novel dynamic programming ...Selecting a cost optimum subset of discrete-value dispersion compensation modules (DV-DCMs) subject to maximum module count from an available set of DV-DCMs is a NP-hard problem. We derive a novel dynamic programming algorithm with pseudo-polynomial time bound and show that DV-DCM cost re-scaling can improve the running time.展开更多
Plasmonic particle-on-film nanocavities,supporting gap modes with ultra-small volume,provide a great solution to boost light–matter interactions at the nanoscale.In this work,we report on the photoluminescence(PL)enh...Plasmonic particle-on-film nanocavities,supporting gap modes with ultra-small volume,provide a great solution to boost light–matter interactions at the nanoscale.In this work,we report on the photoluminescence(PL)enhancement of monolayer MoS_(2) using high order modes of an Au nanosphere dimer-on-film nanocavity(DoFN).The high order plasmon modes,consisting of two bonding quadrupoles in the dimer and their images in the Au film,are revealed by combining the polarization-resolved scattering spectra with the numerical simulations.Further integrating the monolayer MoS_(2) into the DoFN,these high order modes are used to enhance PL intensity through simultaneously boosting the absorption and emission processes,producing a 1350-fold enhancement factor.It opens an avenue to enhance the light–matter interaction with high order plasmon modes and may find applications in future optoelectronics and nanophotonics devices.展开更多
In the last decade,artificial intelligence(AI)techniques have been extensively used for maximum power point tracking(MPPT)in the solar power system.This is because conventional MPPT techniques are incapable of trackin...In the last decade,artificial intelligence(AI)techniques have been extensively used for maximum power point tracking(MPPT)in the solar power system.This is because conventional MPPT techniques are incapable of tracking the global maximum power point(GMPP)under partial shading condition(PSC).The output curve of the power versus voltage for a solar panel has only one GMPP and multiple local maximum power points(MPPs).The integration of AI in MPPT is crucial to guarantee the tracking of GMPP while increasing the overall efficiency and performance of MPPT.The selection of AI-based MPPT techniques is complicated because each technique has its own merits and demerits.In general,all of the AI-based MPPT techniques exhibit fast convergence speed,less steady-state oscillation and high efficiency,compared with the conventional MPPT techniques.However,the AI-based MPPT techniques are computationally intensive and costly to realize.Overall,the hybrid MPPT is favorable in terms of the balance between performance and complexity,and it combines the advantages of conventional and AI-based MPPT techniques.In this paper,a detailed comparison of classification and performance between 6 major AI-based MPPT techniques have been made based on the review and MATLAB/Simulink simulation results.The merits,open issues and technical implementations of AI-based MPPT techniques are evaluated.We intend to provide new insights into the choice of optimal AI-based MPPT techniques.展开更多
In this paper,we describe a new type of digital-to-analog converter(DAC)for optical wireless communication.Conversion occurs in the optical rather than the electrical domain.The overall intensity of the light transmit...In this paper,we describe a new type of digital-to-analog converter(DAC)for optical wireless communication.Conversion occurs in the optical rather than the electrical domain.The overall intensity of the light transmitted by an array of light-emitting diodes(LEDs)is varied by changing the number of LEDs that are switched on.A number of different structures are described,and their compatibility with light dimming and overall energy efficiency are discussed.The linearity of the new DAC depends on the geometry of the system and on the variability in light output between individual LEDs.展开更多
This paper presents a novel robotic sensor system that can monitor volatile chemicals and airflow. The system is modelled on characteristics of the human body that are thought to have a significant influence on the hu...This paper presents a novel robotic sensor system that can monitor volatile chemicals and airflow. The system is modelled on characteristics of the human body that are thought to have a significant influence on the human odour and airflow senses. In particular, the effect of buoyant airflow due to body heat acts to gather volatile chemicals over large areas of the human body and carry them to the nose. It is postulated that this effect increases the receptive area for human olfaction. In addition, the interaction between rising air heated by the body and external airflow produces a temperature distribution about head height that can be used to infer airflow direction and magnitude. A heated sensor system was constructed to investigate these effects and the resulting sensor was mounted on a mobile robot. The design of the sensor system is described. Results are presented which demonstrate its ability to measure airflow direction and detect chemical signals over a wider receptive field compared with an unheated sensor.展开更多
文摘Electro-optical/infrared (EO/IR) sensors and photovoltaic power sources are being developed for a variety of defense and commercial applications. One of the critical technologies that will enhance both EO/IR sensor and photovoltaic module performance is the development of high quality nanostructure-based antireflection coatings. In this paper, we review our work on advanced antireflection structures that have been designed by using a genetic algorithm and fabricated by using oblique angle deposition. The antireflection coatings are designed for the wavelength range of 250 nm to 2500 nm and an incidence angle between 00 and 400. These nanostructured antireflection coatings are shown to enhance the optical transmission through transparent windows over a wide band of interest and minimize broadband reflection losses to less than one percent, a substantial improvement over conventional thin-film antireflection coating technologies.
文摘We review recent work on narrowband orthogonally polarized optical RF single sideband generators as well as dualchannel equalization,both based on high-Q integrated ring resonators.The devices operate in the optical telecommunications C-band and enable RF operation over a range of either fixed or thermally tuneable frequencies.They operate via TE/TM mode birefringence in the resonator.We achieve a very large dynamic tuning range of over 55 dB for both the optical carrier-to-sideband ratio and the dual-channel RF equalization for both the fixed and tunable devices.
文摘In time division synchronous code division multiple access （TD-SCDMA） wireless communication systems, QPSK or 8PSK has been employed to support high data rate services and high efficiency in available bandwidth. The performance of such systems is affected by the phase noise of the microwave local oscillator. The phase noise model of synthesizer and the RF transceiver model for the phase noise effect are proposed for applications of TD-SCDMA systems. The relationship between the power spectral density （PSD） and root mean square （RMS） phase error is given. Then, the error vector magnitude （EVM） performance is analytically evaluated by using the single side band （SSB） phase noise. Theoretical results show agreement with those obtained by measurement data and therefore can be used to derive the TD-SCDMA system performance.
基金supported by the National Natural Science Foundation of China(Grant No.61307128)the National Basic Research Program of China(GrantNo.2010CB327505)+1 种基金the Specialized Research Found for the Doctoral Program of Higher Education of China(Grant No.20131101120027)the Basic Research Foundation of Beijing Institute of Technology of China(Grant No.20120542015)
文摘We propose a novel hybrid phase-locked loop （PLL） architecture for overcoming the trade-off between fast locking time and low spur. To reduce the settling time and meanwhile suppress the reference spurs, we employ a wide-band single-path PLL and a narrow-band dual-path PLL in a transient state and a steady state, respectively, by changing the loop bandwidth according to the gain of voltage controlled oscillator （VCO） and the resister of the loop filter. The hybrid PLL is implemented in a 0.18-μm complementary metal oxide semiconductor （CMOS） process with a total die area of 1.4×0.46 mm2. The measured results exhibit a reference spur level of lower than -73 dB with a reference frequency of 10 MHz and a settling time of 20 μs with 40 MHz frequency jump at 2 GHz. The total power consumption of the hybrid PLL is less than 27 mW with a supply voltage of 1.8 V.
基金Project supported by the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20110185110014)the Fundamental Research Funds for the Central Universities,China (Grant No. E022050205)
文摘In this paper, we demonstrate six types of metamaterial absorbers （MMAs） by measuring their absorptivities in an X-band （8 12 GHz） rectangular waveguide. Some of the MMAs have been demonstrated previously by using the free space measurement method, and the others are proposed firstly in this paper. The measured results show that all of the six MMAs exhibit high absorptivities above 98%, which have similar absorbing characteristics to those measured in the free space. The numerically obtained surface current densities for each MMA show that the absorbing mechanism is the same as that under the free space conditions. Such a demonstration method is superior to the conventional free space measurement method due to the small-scale test samples required, the simple measure device, and its low cost. Most importantly, the proposed method opens a way to enable MMAs to be used in microwave applications such as matched terminations.
文摘One example of an artificial intelligence ethical dilemma is the autonomous vehicle situation presented by Massachusetts Institute of Technology researchers in the Moral Machine Experiment.To solve such dilemmas,the MIT researchers used a classic statistical method known as the hierarchical Bayesian(HB)model.This paper builds upon previous work for modeling moral decision making,applies a deep learning method to learn human ethics in this context,and compares it to the HB approach.These methods were tested to predict moral decisions of simulated populations of Moral Machine participants.Overall,test results indicate that deep neural networks can be effective in learning the group morality of a population through observation,and outperform the Bayesian model in the cases of model mismatches.
文摘Given a set of lightpath connection requests in an all-10 Gb/s optical dense wavelength division multiplexed (DWDM) Ethernet network, lightpaths are designed. In addition the wavelength channels are assigned subject to minimization of the channel blocking and provisional requests satisfying the limits due to accumulative linear dispersion effects over the hops. This paper proposes a routing and wavelength assignment scheme for DWDM long-haul optical networks that includes routing, assignment and reservation of different wavelength channels operating under the Generalized Multiprotocol Label Switching (GMPLS) environment. The GMPLS framework can offer an approach to implement IP over DWDM with variable weighting assignments of routes based on the limitations due to residual dispersion accumulated on the lightwave path. The modeling is implemented under the framework of an object-oriented modeling platform OMNeT++. Network performance tests are evaluated based mainly on a long-haul terrestrial fiber mesh network composed of as well as three topologies structured as chain, ring, and mesh configurations. Blocking probability of lightpath connection requests are examined with the average link utilization in the network employing variable number of wavelength channels in association with the limits of route distance due to linear chromatic and polarization mode dispersion effects.
基金National Natural Science Foundation of China(NSFC)(11574308,61701303)Natural Science Foundation of Shanghai(17PJ1404100,17ZR1414300)
文摘We propose and experimentally demonstrate the operation of an electrically tunable, broadband coherent perfect absorption(CPA) at microwave frequencies by harnessing the CPA features of a graphene–electrolyte–graphene sandwich structure(GSS). Using both a simplified lumped circuit model and full-wave numerical simulation, it is found that the microwave coherent absorptivity of the GSS can be tuned dynamically from nearly 50% to 100% by changing the Fermi level of the graphene. Strikingly, our simplified lumped circuit model agrees very well with the full-wave numerical model, offering valuable insight into the CPA operation of the device. The angle dependency of coherent absorption in the GSS is further investigated, making suggestions for achieving CPA at wide angles up to 80°. To show the validity and accuracy of our theory and numerical simulations, a GSS prototype is fabricated and measured in a C-band waveguide system. The reasonably good agreement between the experimental and the simulated results confirms that the tunable coherent absorption in GSS can be electrically controlled by changing the Fermi level of the graphene.
文摘We review recent work on broadband RF channelizers based on integrated optical frequency Kerr micro-combs combined with passive micro-ring resonator filters,with microcombs having channel spacings of 200 and 49 GHz.This approach to realizing RF channelizers offers reduced complexity,size,and potential cost for a wide range of applications to microwave signal detection.
文摘目的:建立和验证一个涉及多级临床场景的白内障协作通用的人工智能(artificial intelligence,AI)管理平台,探索基于AI的医疗转诊模式,以提高协作效率和资源覆盖率。方法:训练和验证的数据集来自中国AI医学联盟,涵盖多级医疗机构和采集模式。使用三步策略对数据集进行标记:1)识别采集模式;2)白内障诊断包括正常晶体眼、白内障眼或白内障术后眼;3)从病因和严重程度检测需转诊的白内障患者。此外,将白内障AI系统与真实世界中的居家自我监测、初级医疗保健机构和专科医院等多级转诊模式相结合。结果:通用AI平台和多级协作模式在三步任务中表现出可靠的诊断性能:1)识别采集模式的受试者操作特征(receiver operating characteristic curve,ROC)曲线下面积(area under the curve,AUC)为99.28%~99.71%);2)白内障诊断对正常晶体眼、白内障或术后眼,在散瞳-裂隙灯模式下的AUC分别为99.82%、99.96%和99.93%,其他采集模式的AUC均>99%;3)需转诊白内障的检测(在所有测试中AUC>91%)。在真实世界的三级转诊模式中,该系统建议30.3%的人转诊,与传统模式相比,眼科医生与人群服务比率大幅提高了10.2倍。结论:通用AI平台和多级协作模式显示了准确的白内障诊断性能和有效的白内障转诊服务。建议AI的医疗转诊模式扩展应用到其他常见疾病和资源密集型情景当中。
基金funded by the Australian Research for Global Power System Transformation(Stage 2)Topic 2 and partially funded by the Australian Renewable Energy Agency(Grant No.:2023/ARP010)。
文摘Traditional analytical approaches for stability assessment of inverter-based resources(IBRs),often requiring detailed knowledge of IBR internals,become impractical due to IBRs’proprietary nature.Admittance measurements,relying on electromagnetic transient simulation or laboratory settings,are not only time-intensive but also operationally inflexible,since various non-linear control loops make IBRs’admittance models operating-point dependent.Therefore,such admittance measurements must be performed repeatedly when operating point changes.To avoid time-consuming and cumbersome measurements,admittance estimation for arbitrary operating points is highly desirable.However,existing admittance estimation algorithms usually face challenges in versatility,data demands,and accuracy.Addressing this challenge,this letter presents a simple and efficient admittance estimation method for blackboxed IBRs,by utilizing a minimal set of seven operating points to solve a homogeneous linear equation system.Case studies demonstrate this proposed method ensures high accuracy across various types of IBRs.Estimation accuracy is satisfying even when non-negligible measurement errors exist.
基金funding from the European Union’s Horizon 2020 Research and Innovation Programme(No.731767)in the context of the SOCIALENERGY project.
文摘Liberalized electricity markets,smart grids and high penetration of renewable energy sources(RESs)led to the development of novel markets,whose objective is the harmonization between production and demand,usually noted as real time of flexibility markets.This necessitates the development of novel pricing schemes able to allow energy service providers(ESPs)to maximize their aggregated profits from the traditional markets(trading between wholesale/day-ahead and retail markets)and the innovative flexibility markets.In the same time,ESPs have to offer their end users(consumers)competitive(low cost)energy services.In this context,novel pricing schemes must act,among others,as automated demand side management(DSM)techniques that are able to trigger the desired behavioral changes according to the flexibility market prices in energy consumption curves(ECCs)of the consumers.Energy pricing schemes proposed so far,e.g.realtime pricing,interact in an efficient way with wholesale market.But they do not provide consumers with strong enough financial incentives to modify their energy consumption habits towards energy cost curtailment.Thus,they do not interact efficiently with flexibility markets.Therefore,we develop a flexibility real-time pricing(FRTP)scheme,which offers a dynamically adjustable level of financial incentives to participating users by fairly rewarding the ones that make desirable behavioral changes in their ECCs.Performance evaluation results demonstrate that the proposed FRTP is able to offer a 15%–30%more attractive trade-off between the stacked profits of ESPs,i.e.the sum of the profits from retail and flexibility markets,and the satisfaction of consumers.
文摘Matryoshka-caged gold nanorods （mCGNRs） were successfully synthesized by alternating between a seed-mediated silver-coating method and galvanic replacement reactions （GRRs）. As the number of matryoshka layers of the mCGNRs increased, the plasmon resonance peak broadened and was red-shifted, and the catalytic activity towards the reduction of 4-nitrophenol （4-NTP） increased. When mCGNRs with 6 layers were used as nanocatalysts in the reduction of 4-nitrophenol, the reaction rate coefficient was 5.2- and 3.7-times higher than that of the gold-nanorod- and caged-gold-nanorod-catalyzed reductions of 4-nitrophenol, respectively. In addition, the surface-plasmon-resonance-based absorption of light enhanced the catalytic performance of the mCGNRs. With the support of a polyurethane foam, the mCGNRs synthesized in this study can be applied as recydable heterogeneous catalysts for the reduction of 4-nitrophenol.
基金This research is supported by the National Research Foundation Singapore under its AI Singapore Programme(Award Number:AISG-GC-2019-002)National Key Research and Development Program of China(Grant No.2019YFB2004800 and Project No.R-2020-S-002).
文摘The era of artificial intelligence and internet of things is rapidly developed by recent advances in wearable electronics.Gait reveals sensory information in daily life containing personal information,regarding identification and healthcare.Current wearable electronics of gait analysis are mainly limited by high fabrication cost,operation energy consumption,or inferior analysis methods,which barely involve machine learning or implement nonoptimal models that require massive datasets for training.Herein,we developed low-cost triboelectric intelligent socks for harvesting waste energy from low-frequency body motions to transmit wireless sensory data.The sock equipped with self-powered functionality also can be used as wearable sensors to deliver information,regarding the identity,health status,and activity of the users.To further address the issue of ineffective analysis methods,an optimized deep learning model with an end-to-end structure on the socks signals for the gait analysis is proposed,which produces a 93.54%identification accuracy of 13 participants and detects five different human activities with 96.67%accuracy.Toward practical application,we map the physical signals collected through the socks in the virtual space to establish a digital human system for sports monitoring,healthcare,identification,and future smart home applications.
基金National Key R&D Program of China(2017YFA0303800)National Natural Science Foundation of China(NSFC)(11634010,11874050,61675170,61675171,61701303)+2 种基金Key Research and Development Program in Shaanxi Province of China(2017KJXX-12)Natural Science Basic Research Plan in Shaanxi Province(2017JM6022,2018JM1058)Fundamental Research Funds for the Central Universities(3102017zy017,3102018jcc034)
文摘We experimentally demonstrate a scheme to deterministically excite a three-dimensionally oriented electric dipole in a single Au nanosphere by using a tightly focused radially polarized beam whose focal field possesses polarization states along three-dimensional(3D) orientations owing to the spatial overlap between longitudinal and radial electric field components. Experiment observations indicate that the orientation of an excited dipole moment gradually changes from out-of-plane to in-plane when the nanosphere is moved away from the beam center, which is reconfirmed by full-wave simulations. Moreover, rigorous calculation based on Mie theory reveals that a reduced effective ambient permittivity accompanies the rotation of the dipole moment, leading to a blue-shifted and narrowed resonance peak. We envision that our results could find applications in detecting the 3D orientation of isolated molecules and benefit the fine manipulation of light–matter interactions at the single-molecule level.
文摘Selecting a cost optimum subset of discrete-value dispersion compensation modules (DV-DCMs) subject to maximum module count from an available set of DV-DCMs is a NP-hard problem. We derive a novel dynamic programming algorithm with pseudo-polynomial time bound and show that DV-DCM cost re-scaling can improve the running time.
基金National Key Research and Development Program of China(2017YFA0303800)National Natural Science Foundation of China(11634010,11874050,61675170)+1 种基金Open Research Fund of CAS Key Laboratory of Spectral Imaging Technology(LSIT201913W)Fundamental Research Funds for the Central Universities(310201911fz049,3102019JC008).
文摘Plasmonic particle-on-film nanocavities,supporting gap modes with ultra-small volume,provide a great solution to boost light–matter interactions at the nanoscale.In this work,we report on the photoluminescence(PL)enhancement of monolayer MoS_(2) using high order modes of an Au nanosphere dimer-on-film nanocavity(DoFN).The high order plasmon modes,consisting of two bonding quadrupoles in the dimer and their images in the Au film,are revealed by combining the polarization-resolved scattering spectra with the numerical simulations.Further integrating the monolayer MoS_(2) into the DoFN,these high order modes are used to enhance PL intensity through simultaneously boosting the absorption and emission processes,producing a 1350-fold enhancement factor.It opens an avenue to enhance the light–matter interaction with high order plasmon modes and may find applications in future optoelectronics and nanophotonics devices.
基金supported by the School of EngineeringMonash University Malaysia
文摘In the last decade,artificial intelligence(AI)techniques have been extensively used for maximum power point tracking(MPPT)in the solar power system.This is because conventional MPPT techniques are incapable of tracking the global maximum power point(GMPP)under partial shading condition(PSC).The output curve of the power versus voltage for a solar panel has only one GMPP and multiple local maximum power points(MPPs).The integration of AI in MPPT is crucial to guarantee the tracking of GMPP while increasing the overall efficiency and performance of MPPT.The selection of AI-based MPPT techniques is complicated because each technique has its own merits and demerits.In general,all of the AI-based MPPT techniques exhibit fast convergence speed,less steady-state oscillation and high efficiency,compared with the conventional MPPT techniques.However,the AI-based MPPT techniques are computationally intensive and costly to realize.Overall,the hybrid MPPT is favorable in terms of the balance between performance and complexity,and it combines the advantages of conventional and AI-based MPPT techniques.In this paper,a detailed comparison of classification and performance between 6 major AI-based MPPT techniques have been made based on the review and MATLAB/Simulink simulation results.The merits,open issues and technical implementations of AI-based MPPT techniques are evaluated.We intend to provide new insights into the choice of optimal AI-based MPPT techniques.
基金This work was supported under Australian Research Council Discovery funding schemes DP1094218 and DP130101265.
文摘In this paper,we describe a new type of digital-to-analog converter(DAC)for optical wireless communication.Conversion occurs in the optical rather than the electrical domain.The overall intensity of the light transmitted by an array of light-emitting diodes(LEDs)is varied by changing the number of LEDs that are switched on.A number of different structures are described,and their compatibility with light dimming and overall energy efficiency are discussed.The linearity of the new DAC depends on the geometry of the system and on the variability in light output between individual LEDs.
文摘This paper presents a novel robotic sensor system that can monitor volatile chemicals and airflow. The system is modelled on characteristics of the human body that are thought to have a significant influence on the human odour and airflow senses. In particular, the effect of buoyant airflow due to body heat acts to gather volatile chemicals over large areas of the human body and carry them to the nose. It is postulated that this effect increases the receptive area for human olfaction. In addition, the interaction between rising air heated by the body and external airflow produces a temperature distribution about head height that can be used to infer airflow direction and magnitude. A heated sensor system was constructed to investigate these effects and the resulting sensor was mounted on a mobile robot. The design of the sensor system is described. Results are presented which demonstrate its ability to measure airflow direction and detect chemical signals over a wider receptive field compared with an unheated sensor.
