Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and str...Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.展开更多
This paper proposes a simple solution for the stabilization of a mini-quadcopter carrying a 3DoF（degrees of freedom） manipulator robot in order to enhance its achievable workspace and application profile. Since the ...This paper proposes a simple solution for the stabilization of a mini-quadcopter carrying a 3DoF（degrees of freedom） manipulator robot in order to enhance its achievable workspace and application profile. Since the motion of the arm induces torques which degrade the stability of the system, in the present work, we consider the stabilization of both subsystems： the quadcopter and the robotic arm. The mathematical model of the system is based on quaternions. Likewise, an attitude control law consisting of a bounded quaternion-based feedback stabilizes the quadcopter to a desired attitude while the arm is evolving. The next stage is the translational dynamics which is simplified for control（nonlinear） design purposes. The aforementioned controllers are based on saturation functions whose stability is explicitly proved in the Lyapunov sense. Finally, experimental results and a statistical study validate the proposed control strategy.展开更多
Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatm...Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatment and detecting relapse.Here,a highly enhanced plasmonic biosensor that can overcome this challenge is developed using atomically thin two-dimensional phase change nanomaterial.By precisely engineering the configuration with atomically thin materials,the phase singularity has been successfully achieved with a significantly enhanced lateral position shift effect.Based on our knowledge,it is the first experimental demonstration of a lateral position signal change>340μm at a sensing interface from all optical techniques.With this enhanced plasmonic effect,the detection limit has been experimentally demonstrated to be 10^(-15) mol L^(−1) for TNF-α cancer marker,which has been found in various human diseases including inflammatory diseases and different kinds of cancer.The as-reported novel integration of atomically thin Ge_(2)Sb_(2)Te_(5) with plasmonic substrate, which results in a phase singularity and thus a giant lateral position shift, enables the detection of cancer markers with low molecular weight at femtomolar level. These results will definitely hold promising potential in biomedical application and clinical diagnostics.展开更多
An ultrasound wave is a kind of acoustic signal with a frequency greater than 20 kHz,which is widely used in diverse fields such as medical imaging diagnosis,nondestructive testing and resource exploration.A variety o...An ultrasound wave is a kind of acoustic signal with a frequency greater than 20 kHz,which is widely used in diverse fields such as medical imaging diagnosis,nondestructive testing and resource exploration.A variety of ultrasound sensors have been developed for ultrasound detection.Particularly for photoacoustic imaging,specialized ultrasound sensors with high sensitivity,small size,and broad bandwidth are needed.However,achieving such sensor perform-ance still poses a great challenge to the current state-of-the-art in ultrasound sensor technology.A recent work pub-lished in Opto-Electronic Advances(DOI:10.29026/oea.2022.200076)proposes a microfiber-based ultrasound sensor that breaks the limitations of existing ultrasound sensors.Benefiting from the large evanescent field characteristic of mi-crofiber,combined with the coherent detection technology,the proposed sensor realized highly sensitive ultrasound de-tection and demonstrated excellent performance in high-resolution photoacoustic imaging.The highly sensitive and mini-aturized microfiber ultrasound sensor provides a competitive alternative for various applications,such as endoscopic photoacoustic imaging of the intestinal tract and blood vessels in animals.展开更多
A discrete predictor-based control method is developed for a class of linear time-invariant networked control systems with a sensor-to-controller time-varying delay and a controller-to-actuator uncertain constant dela...A discrete predictor-based control method is developed for a class of linear time-invariant networked control systems with a sensor-to-controller time-varying delay and a controller-to-actuator uncertain constant delay,which can be potentially applied to vision-based control systems.The control scheme is composed of a state prediction and a discrete predictor-based controller.The state prediction is used to compensate for the effect of the sensor-to-controller delay,and the system can be stabilized by the discrete predictor-based controller.Moreover,it is shown that the control scheme is also robust with respect to slight message rejections.Finally,the main theoretical results are illustrated by simulation results and experimental results based on a networked visual servo inverted pendulum system.展开更多
This article describes a new wave propagation model based on Monte-Carlo particle-tracing. This model relies on Monte-Carlo integration and Huygens currents radiating. The particles used to compute the field permit to...This article describes a new wave propagation model based on Monte-Carlo particle-tracing. This model relies on Monte-Carlo integration and Huygens currents radiating. The particles used to compute the field permit to consider the interferences. This model includes the diffraction of the surface without edge computation. The implementation of this propagation model is based on a image synthesis renderer. The results of this model are studied in far field situation with perfectly conducting shapes, by comparing results with a classical MoM method.展开更多
As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. Thi...As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.展开更多
With the ever-growing requirement for higher data rates, terminals supporting multiple-input multiple-output (MIMO) technologies are being developed for next-generation. As for wireless device manufacturers, a radio p...With the ever-growing requirement for higher data rates, terminals supporting multiple-input multiple-output (MIMO) technologies are being developed for next-generation. As for wireless device manufacturers, a radio performance evaluation of multi-antenna terminals in desired environments is mandatory before product release. This paper discusses the Over the Air (OTA) performance evaluation of antenna diversity systems in Indoor and Outdoor multi-path propagation channel models inside anechoic chamber, in terms of correlation coefficients and diversity gain (DG). These channel models have been emulated in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading. For this purpose, SATIMO SG24 measurement system has been used. However, the actual configuration of this system is not able to emulate desired realistic environments. Therefore, an innovative methodology based on the SG24 probes control has been developed. The obtained results in simulations and measurements have shown a good agreement.展开更多
This paper presents a new method for fluid simulation based on Stochastic Rotation Dynamics. The SRD model relies on a particle-based representation, but does not consider incompressibility. We generalize this model b...This paper presents a new method for fluid simulation based on Stochastic Rotation Dynamics. The SRD model relies on a particle-based representation, but does not consider incompressibility. We generalize this model by introducing additional computation steps in order to handle this type of behavior, and also two-way coupling between the fluid and immersed objects. As a proof of concept, our method is implemented on the CPU to produce different types of simulations such as dam-break flood, falling droplets and mixing of two fluids.展开更多
New generation passive optical network aims at providing more than 100 Gb/s capacity. Thanks to recent progress enabling a variety of optical transceivers up to 40 Gb/s, many evolution possibilities to 200G PONs （pas...New generation passive optical network aims at providing more than 100 Gb/s capacity. Thanks to recent progress enabling a variety of optical transceivers up to 40 Gb/s, many evolution possibilities to 200G PONs （passive optical network） could be investigated. This work proposes two directly deployable cases of evolution to 200G PON based on the combination of these improved optical transceivers and WDM （wavelength division multiplexing）. The physical layer of the optical network has been simulated with OptiSystem software to show the communication links performances behavior when considering key components parameters in order to achieve good network design for a given area. The complexity of the proposed architectures and financial cost comparisons are also discussed.展开更多
Dielectric resonators are key components in many microwave and millimetre wave circuits and applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. Multilayered and...Dielectric resonators are key components in many microwave and millimetre wave circuits and applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. Multilayered and bulk low-loss single crystal and polycrystalline dielectric structures have become very important for designing these devices. Proper design requires careful electromagnetic characterisation of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering Gallery mode technique, which has now become the standard for characterizing low-loss structures. This paper will review some of the common characterisation techniques used in the microwave to millimetre wave frequency regime.展开更多
This paper present electrical networks, with topological modelisations, generalized cross talked functions implemented in a Kron＇s formalism; Coupling functions are called chords and give a powerful extension to the ...This paper present electrical networks, with topological modelisations, generalized cross talked functions implemented in a Kron＇s formalism; Coupling functions are called chords and give a powerful extension to the method. Applied in electromagnetic compatibility, it has proven its efficiency in time computation and accuracy. The paper review the Kron＇s formalism, a mathematical modelisation of currents by tensorial analysis and topologie, the string principles, and an application, at the end, we propose power-chopper modeling.展开更多
The overall purpose of the present study is basically to understand the manifestation of the thermo-electrical properties of the matrix ZnO-P<sub>2</sub>O<sub>5</sub> first, and of the ZnO-P<...The overall purpose of the present study is basically to understand the manifestation of the thermo-electrical properties of the matrix ZnO-P<sub>2</sub>O<sub>5</sub> first, and of the ZnO-P<sub>2</sub>O<sub>5</sub> composites loaded with different volume fractions of nickel (Ni) as conductive fillers. In the matrix ZnO-P<sub>2</sub>O<sub>5</sub>, the values of electrical conductivity varied between 1.14 × 10<sup>-8</sup> and 7.8 × 10<sup>-7</sup> (S/cm), and the Seebeck coefficient value varied between minimal value 265 and maximal value 670 (μV/K) in the studied temperature. In composite ZnO-P<sub>2</sub>O<sub>5</sub>/Ni, it was shown that the Seebeck coefficient changed from high positive to negative values when the filler amount was increased, indicating a non-conducting to conducting phase transition. Such behavior exhibits that this transition is accompanied by the passing of carrier charge from p to n type. The study of thermoelectrically transport for high volume fraction of filler enabled the achievement, for the first time on this kind of composites, of an original transition called PTC transition. Thus, highest values of power factor (PF = S<sup>2</sup> ≈ 2 × 10<sup>-3</sup> W·m<sup>-1</sup><sub>·</sub>K<sup>-2</sup> at 407 K) were obtained, giving a possibility of industrial applications.展开更多
In a sustainable development context, the monitoring systems are essential to study the building energy performances. With the recent technology advances, these systems can be based on wireless sensor networks, where ...In a sustainable development context, the monitoring systems are essential to study the building energy performances. With the recent technology advances, these systems can be based on wireless sensor networks, where the energy efficiency is the main design challenge. To this end, most of the studies focus on low power Medium Access Control (MAC) protocols to reduce the overall energy consumption of a network. Nevertheless, the performances assessment of these protocols is generally not performed in a realistic way, and does not take into account the performances of the other layers of the OSI model. In this paper, we propose a cross-layer methodology to assess the real performances of a MAC protocol by taking into account the traffic volume, the synchronization losses and more particularly the physical layer performances through a Bit Error Rate (BER) criterion. The simulation results demonstrate clearly the physical layer impact on a sensor lifetime. Finally, the proposal of an energy efficient MAC protocol for a wireless sensor network dedicated to an application of building monitoring is proposed.展开更多
This study at the Esmeralda Mine,part of the El Teniente Division of CODELCO,investigates optimizing hydraulic fracturing(HF)holes’spatial distribution to improve rock material production in one of the world's la...This study at the Esmeralda Mine,part of the El Teniente Division of CODELCO,investigates optimizing hydraulic fracturing(HF)holes’spatial distribution to improve rock material production in one of the world's largest copper-molybdenum deposits.Utilizing diverse data sources,including borehole,oriented borehole,and photogrammetry data,along with hang-up frequency and hydrofracturing details,we applied discrete fracture network(DFN)modeling to analyze in-situ block size distribution and fragmentation.These results are based on 12,000 realizations of discrete fracture network(DFN)models using R-Dis-Frag computer pacakge at real cave volumes of 200 m200 m200 m,with varying parameters,which significantly enhances their reliability.The incorporation of DFN modeling and geostatistical simulation allows for capturing the interaction berween several spatial variables and explaining the variations observed in the production results at the draw points.Keyfindings of spatio-statistical analysis highlight the significance of volumetric fracture intensity(P32)and extraction column height in reducing hang-up events and enhancing fragmentation efficiency.The study integrates HF-induced and natural fracture intensities,revealing that higher P32 values and higher draw columns correlate with fewer hang-ups and better fragmentation.We recommend non-regular HF patterns for high P32 zones to improve operational efficiency.This research provides insights into optimizing mining operations,acknowledging the limitations of HF propagation efficacy and paving the way for further exploration into the interplay between hydraulic fracturing and natural discontinuities.展开更多
Coherent Raman scattering microscopy is a fast,label-free,and chemically specific imaging technique that shows high potential for future in vivo optical histology.However,the imaging depth in tissues is limited to the...Coherent Raman scattering microscopy is a fast,label-free,and chemically specific imaging technique that shows high potential for future in vivo optical histology.However,the imaging depth in tissues is limited to the sub-millimeter range because of absorption and scattering.Realization of coherent Raman imaging using a fiber endoscope system is a crucial step towards imaging deep inside living tissues and providing information that is inaccessible with current microscopy tools.Until now,the development of coherent Raman endoscopy has been hampered by several issues,mainly related to the fiber delivery of the excitation pulses and signal collection.Here,we present a flexible,compact,coherent Raman,and multimodal nonlinear endoscope(4.2mm outer diameter,71mm rigid length)based on a resonantly scanned hollow-core Kagomé-lattice double-clad fiber.The fiber design enables distortion-less,background-free delivery of femtosecond excitation pulses and back-collection of nonlinear signals through the same fiber.Sub-micrometer spatial resolution over a large field of view is obtained by combination of a miniature objective lens with a silica microsphere lens inserted into the fiber core.We demonstrate high-resolution,high-contrast coherent anti-Stokes Raman scattering,and second harmonic generation endoscopic imaging of biological tissues over a field of view of 320μm at a rate of 0.8 frames per second.These results pave the way for intraoperative label-free imaging applied to real-time histopathology diagnosis and surgery guidance.展开更多
Remarkable recent demonstrations of ultra-low-loss inhibited-coupling(1C)hollow-core photonic-crystal fibres(HCPCFs)established them as serious candidates for next-generation long-haul fibre optics systems.A hindrance...Remarkable recent demonstrations of ultra-low-loss inhibited-coupling(1C)hollow-core photonic-crystal fibres(HCPCFs)established them as serious candidates for next-generation long-haul fibre optics systems.A hindrance to this prospect and also to short-haul applications such as micromachining,where stable and high-quality beam delivery is needed,is the difficulty in designing and fabricating an IC-guiding fibre that combines ultra-low loss,truly robust single-modeness,and polarisation-maintaining operation.The design solutions proposed to date require a trade-off between low loss and truly single-modeness.Here,we propose a novel IC-HCPCF for achieving low-loss and effective single-mode operation.The fibre is endowed with a hybrid cladding composed of a Kagome-tubular lattice(HKT).This new concept of a microstructured cladding allows us to significantly reduce the confinement loss and,at the same time,preserve truly robust single-mode operation.Experimental results show an HKT-IC-HCPCF with a minimum loss of 1.6dB/km at 1050 nm and a higher-order mode extinction ratio as high as 47.0 dB for a 10 m long fibre.The robustness of the fibre single-modeness is tested by moving the fibre and varying the coupling conditions.The design proposed herein opens a new route for the development of HCPCFs that combine robust ultra-low-loss transmission and single-mode beam delivery and provides new insight into IC guidance.展开更多
We review the use of hollow-core photonic crystal fibre(HC-PCF)for high power laser beam delivery.A comparison of bandgap HC-PCF with Kagome-lattice HC-PCF on the geometry,guidance mechanism,and optical properties sho...We review the use of hollow-core photonic crystal fibre(HC-PCF)for high power laser beam delivery.A comparison of bandgap HC-PCF with Kagome-lattice HC-PCF on the geometry,guidance mechanism,and optical properties shows that the Kagome-type HC-PCF is an ideal host for high power laser beam transportation because of its large core size,low attenuation,broadband transmission,single-mode guidance,low dispersion and the ultra-low optical overlap between the core-guided modes and the silica core-surround.The power handling capability of Kagome-type HC-PCF is further experimentally demonstrated by millijoule nanosecond laser spark ignition and^100μJ sub-picosecond laser pulse transportation and compression.展开更多
The mid-infrared spectral region opens up new possibilities for applications such as molecular spectroscopy with high spatial and frequency resolution.For example,the mid-infrared light provided by synchrotron sources...The mid-infrared spectral region opens up new possibilities for applications such as molecular spectroscopy with high spatial and frequency resolution.For example,the mid-infrared light provided by synchrotron sources has helped for early diagnosis of several pathologies.However,alternative light sources at the table-top scale would enable better access to these state-of-the-art characterizations,eventually speeding up research in biology and medicine.Midinfrared supercontinuum generation in highly nonlinear waveguides pumped by compact fiber lasers represents an appealing alternative to synchrotrons.Here,we introduce orientation-patterned gallium arsenide waveguides as a new versatile platform for mid-infrared supercontinuum generation.Waveguides and fiber-based pump lasers are optimized in tandem to allow for the group velocities of the signal and the idler waves to match near the degeneracy point.This configuration exacerbates supercontinuum generation from 4 to 9μm when waveguides are pumped at 2750 nm with few-nanojoule energy pulses.The brightness of the novel mid-infrared source exceeds that of the thirdgeneration synchrotron source by a factor of 20.We also show that the nonlinear dynamics is strongly influenced by the choice of waveguide and laser parameters,thus offering an additional degree of freedom in tailoring the spectral profile of the generated light.Such an approach then opens new paths for high-brightness mid-infrared laser sources development for high-resolution spectroscopy and imaging.Furthermore,thanks to the excellent mechanical and thermal properties of the waveguide material,further power scaling seems feasible,allowing for the generation of watt-level ultra-broad frequency combs in the mid-infrared.展开更多
We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultralong fiber laser.This new concept is supported by experimental results sho...We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultralong fiber laser.This new concept is supported by experimental results showing how the radiofrequency spectrum of the laser can be exploited as a carrier to exchange information.The test bench for our proof of principle is a 50-km-long fiber laser linking two users,Alice and Bob,where each user can randomly add an extra 1-km-long segment of fiber.The choice of laser length is driven by two independent random binary values,which makes such length become itself a random variable.The security of key exchange is ensured whenever the two independent random choices lead to the same laser length and,hence,to the same free spectral range.展开更多
基金This work is partially supported by National Natural Science Foundation of China （11774102）, the Scientific Research Funds and Promotion Program for Young and Middle-aged Teacher in Science ＆ Technology Research of Huaqiao University （ZQN-YXS04, 17BS412）, Open Fund of IPOC （BUPT）, National Research Foundation Singapore （NRF） （NRF-CRP13-2014-05）, European Union＇s Horizon 2020 Research and Innovation Programme under the Marie Sklodowska-Curie Grant Agreement （No. 798916） and Singapore Ministry of Education Academic Research Fund Tier 1 （RG89/16）.
文摘Optical whispering gallery mode （WGM） microresonators have attracted great attention due to their remarkable proper- ties such as extremely high quality factor, small mode volume, tight confinement of modes, and strong evanescent field. All these properties of WGM microresonators have ensured their great potentials for applications, such as physical sen- sors, bio/chemical sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced. The geometries of WGM optical microcavities are presented based on their fabri- cation methods. This is followed by the discussion on the state-of-the-art applications of WGM microresonators in sen- sors and microlasers.
基金supported by CONACYT-Mexico,Lab Ex PERSYVAL-Lab(No.ANR-11-LABX-0025)Equipex ROBOTEX(No.ANR-10-EQPX-44-01)
文摘This paper proposes a simple solution for the stabilization of a mini-quadcopter carrying a 3DoF（degrees of freedom） manipulator robot in order to enhance its achievable workspace and application profile. Since the motion of the arm induces torques which degrade the stability of the system, in the present work, we consider the stabilization of both subsystems： the quadcopter and the robotic arm. The mathematical model of the system is based on quaternions. Likewise, an attitude control law consisting of a bounded quaternion-based feedback stabilizes the quadcopter to a desired attitude while the arm is evolving. The next stage is the translational dynamics which is simplified for control（nonlinear） design purposes. The aforementioned controllers are based on saturation functions whose stability is explicitly proved in the Lyapunov sense. Finally, experimental results and a statistical study validate the proposed control strategy.
基金We thank Shiyue Liu from School of Life Sciences in The Chinese University of Hong Kong for helpful discussions.This work is supported under the PROCORE-France/Hong Kong Joint Research Scheme(F-CUHK402/19)the Research Grants Council,Hong Kong Special Administration Region(AoE/P-02/12,14210517,14207419,N_CUHK407/16)the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No.798916.Y.Wang is supported under the Hong Kong PhD Fellowship Scheme.
文摘Detection of small cancer biomarkers with low molecular weight and a low concentration range has always been challenging yet urgent in many clinical applications such as diagnosing early-stage cancer,monitoring treatment and detecting relapse.Here,a highly enhanced plasmonic biosensor that can overcome this challenge is developed using atomically thin two-dimensional phase change nanomaterial.By precisely engineering the configuration with atomically thin materials,the phase singularity has been successfully achieved with a significantly enhanced lateral position shift effect.Based on our knowledge,it is the first experimental demonstration of a lateral position signal change>340μm at a sensing interface from all optical techniques.With this enhanced plasmonic effect,the detection limit has been experimentally demonstrated to be 10^(-15) mol L^(−1) for TNF-α cancer marker,which has been found in various human diseases including inflammatory diseases and different kinds of cancer.The as-reported novel integration of atomically thin Ge_(2)Sb_(2)Te_(5) with plasmonic substrate, which results in a phase singularity and thus a giant lateral position shift, enables the detection of cancer markers with low molecular weight at femtomolar level. These results will definitely hold promising potential in biomedical application and clinical diagnostics.
文摘An ultrasound wave is a kind of acoustic signal with a frequency greater than 20 kHz,which is widely used in diverse fields such as medical imaging diagnosis,nondestructive testing and resource exploration.A variety of ultrasound sensors have been developed for ultrasound detection.Particularly for photoacoustic imaging,specialized ultrasound sensors with high sensitivity,small size,and broad bandwidth are needed.However,achieving such sensor perform-ance still poses a great challenge to the current state-of-the-art in ultrasound sensor technology.A recent work pub-lished in Opto-Electronic Advances(DOI:10.29026/oea.2022.200076)proposes a microfiber-based ultrasound sensor that breaks the limitations of existing ultrasound sensors.Benefiting from the large evanescent field characteristic of mi-crofiber,combined with the coherent detection technology,the proposed sensor realized highly sensitive ultrasound de-tection and demonstrated excellent performance in high-resolution photoacoustic imaging.The highly sensitive and mini-aturized microfiber ultrasound sensor provides a competitive alternative for various applications,such as endoscopic photoacoustic imaging of the intestinal tract and blood vessels in animals.
基金supported by the China Scholarship Council(CSC)the National Natural Science Foundation of China(92067106)。
文摘A discrete predictor-based control method is developed for a class of linear time-invariant networked control systems with a sensor-to-controller time-varying delay and a controller-to-actuator uncertain constant delay,which can be potentially applied to vision-based control systems.The control scheme is composed of a state prediction and a discrete predictor-based controller.The state prediction is used to compensate for the effect of the sensor-to-controller delay,and the system can be stabilized by the discrete predictor-based controller.Moreover,it is shown that the control scheme is also robust with respect to slight message rejections.Finally,the main theoretical results are illustrated by simulation results and experimental results based on a networked visual servo inverted pendulum system.
文摘This article describes a new wave propagation model based on Monte-Carlo particle-tracing. This model relies on Monte-Carlo integration and Huygens currents radiating. The particles used to compute the field permit to consider the interferences. This model includes the diffraction of the surface without edge computation. The implementation of this propagation model is based on a image synthesis renderer. The results of this model are studied in far field situation with perfectly conducting shapes, by comparing results with a classical MoM method.
文摘As antennas are inherently included recommended in Over-The-Air (OTA) testing, it is important to also consider realistic channel models for the multiple-input multiple-output (MIMO) device performance evaluation. This paper aims to emulate realistic multi-Path propagation channels in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading, inside an anechoic chamber, for antenna diversity measurements. In this purpose, a practical multi-probe anechoic chamber measurement system (MPAC) with 24 probe antennas (SATIMO SG24) has been used. However, the actual configuration of this system is not able to reproduce realistic channels. Therefore, a new method based on the control of the SG24 probes has been developed. At first time, this method has been validated numerically through the comparison of simulated and analytical AoA probability density distributions. At the second time, the performance of an antenna diversity system inside the SG24 has been performed in terms of the correlation coefficient and diversity gain (DG) using an antenna reference system. Simulated and measurements results have shown a good agreement.
文摘With the ever-growing requirement for higher data rates, terminals supporting multiple-input multiple-output (MIMO) technologies are being developed for next-generation. As for wireless device manufacturers, a radio performance evaluation of multi-antenna terminals in desired environments is mandatory before product release. This paper discusses the Over the Air (OTA) performance evaluation of antenna diversity systems in Indoor and Outdoor multi-path propagation channel models inside anechoic chamber, in terms of correlation coefficients and diversity gain (DG). These channel models have been emulated in terms of angles of arrivals (AoA) and cross-polarization ratio (XPR) with Rayleigh fading. For this purpose, SATIMO SG24 measurement system has been used. However, the actual configuration of this system is not able to emulate desired realistic environments. Therefore, an innovative methodology based on the SG24 probes control has been developed. The obtained results in simulations and measurements have shown a good agreement.
基金supported by institutional grants from the LabEX SigmaLim(ANR-10-LABX-0074-01)by the MIRES Federation
文摘This paper presents a new method for fluid simulation based on Stochastic Rotation Dynamics. The SRD model relies on a particle-based representation, but does not consider incompressibility. We generalize this model by introducing additional computation steps in order to handle this type of behavior, and also two-way coupling between the fluid and immersed objects. As a proof of concept, our method is implemented on the CPU to produce different types of simulations such as dam-break flood, falling droplets and mixing of two fluids.
文摘New generation passive optical network aims at providing more than 100 Gb/s capacity. Thanks to recent progress enabling a variety of optical transceivers up to 40 Gb/s, many evolution possibilities to 200G PONs （passive optical network） could be investigated. This work proposes two directly deployable cases of evolution to 200G PON based on the combination of these improved optical transceivers and WDM （wavelength division multiplexing）. The physical layer of the optical network has been simulated with OptiSystem software to show the communication links performances behavior when considering key components parameters in order to achieve good network design for a given area. The complexity of the proposed architectures and financial cost comparisons are also discussed.
文摘Dielectric resonators are key components in many microwave and millimetre wave circuits and applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. Multilayered and bulk low-loss single crystal and polycrystalline dielectric structures have become very important for designing these devices. Proper design requires careful electromagnetic characterisation of low-loss material properties. This includes exact simulation with precision numerical software and precise measurements of resonant modes. For example, we have developed the Whispering Gallery mode technique, which has now become the standard for characterizing low-loss structures. This paper will review some of the common characterisation techniques used in the microwave to millimetre wave frequency regime.
文摘This paper present electrical networks, with topological modelisations, generalized cross talked functions implemented in a Kron＇s formalism; Coupling functions are called chords and give a powerful extension to the method. Applied in electromagnetic compatibility, it has proven its efficiency in time computation and accuracy. The paper review the Kron＇s formalism, a mathematical modelisation of currents by tensorial analysis and topologie, the string principles, and an application, at the end, we propose power-chopper modeling.
文摘The overall purpose of the present study is basically to understand the manifestation of the thermo-electrical properties of the matrix ZnO-P<sub>2</sub>O<sub>5</sub> first, and of the ZnO-P<sub>2</sub>O<sub>5</sub> composites loaded with different volume fractions of nickel (Ni) as conductive fillers. In the matrix ZnO-P<sub>2</sub>O<sub>5</sub>, the values of electrical conductivity varied between 1.14 × 10<sup>-8</sup> and 7.8 × 10<sup>-7</sup> (S/cm), and the Seebeck coefficient value varied between minimal value 265 and maximal value 670 (μV/K) in the studied temperature. In composite ZnO-P<sub>2</sub>O<sub>5</sub>/Ni, it was shown that the Seebeck coefficient changed from high positive to negative values when the filler amount was increased, indicating a non-conducting to conducting phase transition. Such behavior exhibits that this transition is accompanied by the passing of carrier charge from p to n type. The study of thermoelectrically transport for high volume fraction of filler enabled the achievement, for the first time on this kind of composites, of an original transition called PTC transition. Thus, highest values of power factor (PF = S<sup>2</sup> ≈ 2 × 10<sup>-3</sup> W·m<sup>-1</sup><sub>·</sub>K<sup>-2</sup> at 407 K) were obtained, giving a possibility of industrial applications.
文摘In a sustainable development context, the monitoring systems are essential to study the building energy performances. With the recent technology advances, these systems can be based on wireless sensor networks, where the energy efficiency is the main design challenge. To this end, most of the studies focus on low power Medium Access Control (MAC) protocols to reduce the overall energy consumption of a network. Nevertheless, the performances assessment of these protocols is generally not performed in a realistic way, and does not take into account the performances of the other layers of the OSI model. In this paper, we propose a cross-layer methodology to assess the real performances of a MAC protocol by taking into account the traffic volume, the synchronization losses and more particularly the physical layer performances through a Bit Error Rate (BER) criterion. The simulation results demonstrate clearly the physical layer impact on a sensor lifetime. Finally, the proposal of an energy efficient MAC protocol for a wireless sensor network dedicated to an application of building monitoring is proposed.
基金the funding of the Agencia Nacional de Investigación y 761 Desarrollo (ANID), through grant project of Fondecyt Iniciacion No. 11221093Basal Grants Center for Modeling ACE210010 and FB210005
文摘This study at the Esmeralda Mine,part of the El Teniente Division of CODELCO,investigates optimizing hydraulic fracturing(HF)holes’spatial distribution to improve rock material production in one of the world's largest copper-molybdenum deposits.Utilizing diverse data sources,including borehole,oriented borehole,and photogrammetry data,along with hang-up frequency and hydrofracturing details,we applied discrete fracture network(DFN)modeling to analyze in-situ block size distribution and fragmentation.These results are based on 12,000 realizations of discrete fracture network(DFN)models using R-Dis-Frag computer pacakge at real cave volumes of 200 m200 m200 m,with varying parameters,which significantly enhances their reliability.The incorporation of DFN modeling and geostatistical simulation allows for capturing the interaction berween several spatial variables and explaining the variations observed in the production results at the draw points.Keyfindings of spatio-statistical analysis highlight the significance of volumetric fracture intensity(P32)and extraction column height in reducing hang-up events and enhancing fragmentation efficiency.The study integrates HF-induced and natural fracture intensities,revealing that higher P32 values and higher draw columns correlate with fewer hang-ups and better fragmentation.We recommend non-regular HF patterns for high P32 zones to improve operational efficiency.This research provides insights into optimizing mining operations,acknowledging the limitations of HF propagation efficacy and paving the way for further exploration into the interplay between hydraulic fracturing and natural discontinuities.
基金supported by EU-ITN-607842-2013-FINON,FR-“Investissement d’Avenir”-11-IDEX-0001-02,11-INSB-0006,11-EQPX-0017,11-LABX-0007,FR-ANR-14-CE17-0004-01,FR-INSERM-PC201508,EU Regional Development Fund(ERDF)Centre National de la Recherche Scientifique(IRCICA USR 3380)the Chinese Science Council(China)for funding support.
文摘Coherent Raman scattering microscopy is a fast,label-free,and chemically specific imaging technique that shows high potential for future in vivo optical histology.However,the imaging depth in tissues is limited to the sub-millimeter range because of absorption and scattering.Realization of coherent Raman imaging using a fiber endoscope system is a crucial step towards imaging deep inside living tissues and providing information that is inaccessible with current microscopy tools.Until now,the development of coherent Raman endoscopy has been hampered by several issues,mainly related to the fiber delivery of the excitation pulses and signal collection.Here,we present a flexible,compact,coherent Raman,and multimodal nonlinear endoscope(4.2mm outer diameter,71mm rigid length)based on a resonantly scanned hollow-core Kagomé-lattice double-clad fiber.The fiber design enables distortion-less,background-free delivery of femtosecond excitation pulses and back-collection of nonlinear signals through the same fiber.Sub-micrometer spatial resolution over a large field of view is obtained by combination of a miniature objective lens with a silica microsphere lens inserted into the fiber core.We demonstrate high-resolution,high-contrast coherent anti-Stokes Raman scattering,and second harmonic generation endoscopic imaging of biological tissues over a field of view of 320μm at a rate of 0.8 frames per second.These results pave the way for intraoperative label-free imaging applied to real-time histopathology diagnosis and surgery guidance.
基金This work is funded through the PIA 4F project and the region of Nouvelle Aquitaine.
文摘Remarkable recent demonstrations of ultra-low-loss inhibited-coupling(1C)hollow-core photonic-crystal fibres(HCPCFs)established them as serious candidates for next-generation long-haul fibre optics systems.A hindrance to this prospect and also to short-haul applications such as micromachining,where stable and high-quality beam delivery is needed,is the difficulty in designing and fabricating an IC-guiding fibre that combines ultra-low loss,truly robust single-modeness,and polarisation-maintaining operation.The design solutions proposed to date require a trade-off between low loss and truly single-modeness.Here,we propose a novel IC-HCPCF for achieving low-loss and effective single-mode operation.The fibre is endowed with a hybrid cladding composed of a Kagome-tubular lattice(HKT).This new concept of a microstructured cladding allows us to significantly reduce the confinement loss and,at the same time,preserve truly robust single-mode operation.Experimental results show an HKT-IC-HCPCF with a minimum loss of 1.6dB/km at 1050 nm and a higher-order mode extinction ratio as high as 47.0 dB for a 10 m long fibre.The robustness of the fibre single-modeness is tested by moving the fibre and varying the coupling conditions.The design proposed herein opens a new route for the development of HCPCFs that combine robust ultra-low-loss transmission and single-mode beam delivery and provides new insight into IC guidance.
文摘We review the use of hollow-core photonic crystal fibre(HC-PCF)for high power laser beam delivery.A comparison of bandgap HC-PCF with Kagome-lattice HC-PCF on the geometry,guidance mechanism,and optical properties shows that the Kagome-type HC-PCF is an ideal host for high power laser beam transportation because of its large core size,low attenuation,broadband transmission,single-mode guidance,low dispersion and the ultra-low optical overlap between the core-guided modes and the silica core-surround.The power handling capability of Kagome-type HC-PCF is further experimentally demonstrated by millijoule nanosecond laser spark ignition and^100μJ sub-picosecond laser pulse transportation and compression.
基金We acknowledge the financial support from Agence Nationale de la Recherche(ANR-16-CE08-0031 BISCOT,ANR-20-CE42-0003 FLEX-UV,ANR-21-CE24-0001 MIRthFUL)H2020 Future and Emerging Technologies(PETACom 829153)Conseil Régional de Nouvelle-Aquitaine(SIP2,Femto-VO2,MIR-X).
文摘The mid-infrared spectral region opens up new possibilities for applications such as molecular spectroscopy with high spatial and frequency resolution.For example,the mid-infrared light provided by synchrotron sources has helped for early diagnosis of several pathologies.However,alternative light sources at the table-top scale would enable better access to these state-of-the-art characterizations,eventually speeding up research in biology and medicine.Midinfrared supercontinuum generation in highly nonlinear waveguides pumped by compact fiber lasers represents an appealing alternative to synchrotrons.Here,we introduce orientation-patterned gallium arsenide waveguides as a new versatile platform for mid-infrared supercontinuum generation.Waveguides and fiber-based pump lasers are optimized in tandem to allow for the group velocities of the signal and the idler waves to match near the degeneracy point.This configuration exacerbates supercontinuum generation from 4 to 9μm when waveguides are pumped at 2750 nm with few-nanojoule energy pulses.The brightness of the novel mid-infrared source exceeds that of the thirdgeneration synchrotron source by a factor of 20.We also show that the nonlinear dynamics is strongly influenced by the choice of waveguide and laser parameters,thus offering an additional degree of freedom in tailoring the spectral profile of the generated light.Such an approach then opens new paths for high-brightness mid-infrared laser sources development for high-resolution spectroscopy and imaging.Furthermore,thanks to the excellent mechanical and thermal properties of the waveguide material,further power scaling seems feasible,allowing for the generation of watt-level ultra-broad frequency combs in the mid-infrared.
基金This work was supported by the French National Research Agency(grants LABEX SIGMALIM and ANR 08-JCJC-0122 PARADHOQS)the European Research Council(project ULTRALASER)+2 种基金the Leverhulme Trust(grant RPG-278)the Spanish MICINN project TEC2011-27314(RAMAS)We also acknowledge support by the XLIM Institute(grant VIP2013).
文摘We propose a new approach to the generation of an alphabet for secret key exchange relying on small variations in the cavity length of an ultralong fiber laser.This new concept is supported by experimental results showing how the radiofrequency spectrum of the laser can be exploited as a carrier to exchange information.The test bench for our proof of principle is a 50-km-long fiber laser linking two users,Alice and Bob,where each user can randomly add an extra 1-km-long segment of fiber.The choice of laser length is driven by two independent random binary values,which makes such length become itself a random variable.The security of key exchange is ensured whenever the two independent random choices lead to the same laser length and,hence,to the same free spectral range.
