Designing Discrete Predictor-Based Controllers for Networked Control Systems with Time-varying Delays:Application to A Visual Servo Inverted Pendulum System

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.

Evolution to 200G Passive Optical Network

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.

A Wave Propagation Model Based on Monte-Carlo Particle-Tracing

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.

Low-Loss Dielectric Material Characterization and High-Q Resonator Design from Microwave to Millimetre Waves Frequencies

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.

Thermoelectric Properties of ZnO-P2O5/(Ni) Composites

The overall purpose of the present study is basically to understand the manifestation of the thermo-electrical properties of the matrix ZnO-P2O5 first, and of the ZnO-P2O5 composites loaded with different volume fractions of nickel (Ni) as conductive fillers. In the matrix ZnO-P2O5, the values of electrical conductivity varied between 1.14 × 10-8 and 7.8 × 10-7 (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-P2O5/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 = S2 ≈ 2 × 10-3 W·m-1·K-2 at 407 K) were obtained, giving a possibility of industrial applications.

Networks, Topology and Interaction Principle Implemented in the Kron＇s Method

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.

A high-power electromagnetic source for disabling improvised explosive devices

Ultra-wideband(UWB)microwave sources driven by specialised pulsed power generators have experienced a considerable development in the last decade due to their wide domain of new applications such as defence or counter-terrorism activity.The authors present the main findings of a research dedicated to the development of a pulsed power-driven electromagnetic field source for disabling improvised explosive devices(IED).The pulsed power generator driving the source is a 13-stage compact Marx producing voltage pulses reaching an amplitude of 0.5 MV,with a pulse repetition frequency(PRF)of up to 100 Hz.The generator is coupled to a bipolar pulse forming line,providing bipolar pulses with a dV/dt of around 1.6 MV/ns.This pulsed power system feeds an array composed of 16 Koshelev-type UWB antennas through an impedance matching transformer.The resulting electromagnetic source is capable to produce pulsed electric fields(PEFs)having a figure-of-merit(FOM)of 1 MV.First,practical experiments were carried out to study the effects of the PEFs on targets.The targets used in the present study are M2B type flashbulbs,known to have the same susceptibility as the US army M6 detonator.Different configurations of wires(shielded,twisted,etc)with different lengths were used in connecting items inside these targets.The tests were performed by placing the flashbulbs at different distances to determine the essential parameters(i.e.,amplitude,duration,and frequency range)of the PEFs required to trigger them.An overview of the experimental campaign and the main findings are also presented followed by conclusions.

GaAs-chip-based mid-infrared supercontinuum generation

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.

Spatiotemporal mode decomposition of ultrashort pulses in linear and nonlinear graded-index multimode fibers

We develop a spatiotemporal mode decomposition technique to study the spatial and temporal mode power distribution of ultrashort pulses in long spans of graded-index multimode fiber,for different input laser conditions.We find that the beam mode power content in the dispersive pulse propagation regime can be described by the Bose-Einstein law,as a result of the process of power diffusion from linear and nonlinear mode coupling among nondegenerate mode groups.In the soliton regime,the output mode power distribution approaches the Rayleigh-Jeans law.

High-resolution multimodal flexible coherent Raman endoscope

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.

Interferometer Based on a D-shape Chaotic Optical Fiber for Measurement of Multiparameters

An interferometer based on a D-shape chaotic optical tiber tor measurement ot multiparameters was proposed. The sensing structure relied on a D-shape fiber section spliced in between two singlemode fibers and interrogated in transmission. The optical spectrum was composed by multiple interference loss peaks, which were sensitive to the refractive index, temperature and strain-maximum sensitivities of 95.2 nm/RIU, 10.5 pm/℃ and -3.51 pm/με, respectively, could be achieved.

Rotorcraft with a 3DOF Rigid Manipulator:Quaternion-based Modeling and Real-time Control Tolerant to Multi-body Couplings

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.

Secret key exchange in ultralong lasers by radiofrequency spectrum coding

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.

Femtosecond nonlinear losses in multimode optical fibers

Multimode optical fibers are attracting a growing interest for their capability to transport high-power laser beams,coupled with novel nonlinear optics-based applications.However,optical fiber breakdown occurs when beam intensities exceed a certain critical value.Optical breakdown associated with irreversible modifications of the refractive index,triggered by multiphoton absorption,has been largely exploited for fiber material microstructuration.Here we show that,for light beam intensities slightly below the breakdown threshold,nonlinear absorption strongly affects the dynamics of a propagating beam as well.We experimentally analyze this subthreshold regime and highlight the key role played by spatial self-imaging in graded-index fibers for enhancing nonlinear optical losses.We characterize the nonlinear power transmission properties of multimode fibers for femtosecond pulses propagating in the near-infrared spectral range.We show that an effective N-photon absorption analytical model is able to describe the experimental data well.

Migration of a vascular coil from the common bile duct secondary to vasculobiliary injury after cholecystectomy

A 61-year-old woman had cholangitis secondary to two cholelithiases[one in the common bile duct(CBD)and one in the cystic duct(Mirizzi syndrome)],which was treated by antibiotics.The patient subsequently underwent a shincterotomy with endoscopic retrograde cholangiopancreatography(ERCP)and,finally,a cholecystectomy by coelioscopy.The postoperative course was marked by biliary leakage.She was transferred to our hospital due to haemorrhagic shock and abdominal pain.

Multiphoton ionization of standard optical fibers

Atoms ionization by the simultaneous absorption of multiple photons has found applications in fiber optics,where it leads to unique nonlinear phenomena.To date,studies of the ionization regime have been limited to gas-filled hollow-core fibers.Here,we investigate multiphoton ionization of standard optical fibers,where intense laser pulses ionize the atoms constituting the fiber structure itself,instead of that of the filling gas.We characterize material modifications produced by optical breakdown.Their formation affects laser beam dynamics over hours long temporal scales.The damage features are studied by means of optical microscopy and X-ray microtomography.In the framework of glass photonics,our results pave the way for a novel glass waveguide micromachining technique.