Multichannel Mode Research Articles

Vibration localization prediction and optimal exciter placement for improving the sound field optimization performance of multi-channel distributed mode loudspeakers

This paper describes a method for improving the sound field control performance of multi-channel distributed mode loudspeakers. Recently, studies for sound field control have been conducted using distributed mode loudspeakers rather than conventional cone-type loudspeakers because distributed mode loudspeakers can use the structure itself as a diaphragm. However, when a distributed mode loudspeaker with multi-channel signal processing is used for sound field control, the sound field control performance deteriorates owing to the resonance modes of the panel. In this regard, we improved the sound field control performance of multi-channel distributed mode loudspeakers by increasing vibration localization near the excitation points. To achieve this, we proposed a new formula for predicting the vibration localization near the excitation points in relation to the resonance mode of the panel. Unlike the localization factors currently in use, this formula is designed to predict the vibration localization near the excitation points regardless of the material properties, size, and measurement region of the panel. Thus, this formula can effectively predict the vibration localization in cases where it is difficult to measure the entire region of the structure or in different types of structures. Through this prediction formula, optimal exciter placement is achieved, which maximizes vibration localization near the excitation points. The directivity, radiation efficiency, and reproduction error of sound field optimization are used as measures of sound field control performance. The simulation and experimental results indicate that the rapid increase in reproduction error and the rapid change in sound pressure are suppressed at the natural frequencies of the panel because of the optimal exciter placement.

АЛГОРИТМИЧЕСКОЕ ОБЕСПЕЧЕНИЕ ИНТЕРФЕЙСА УПРАВЛЕНИЯ РОБОТ-ЧЕЛОВЕК ПРИ ВЫДЕЛЕНИИ ЗРИТЕЛЬНЫХ ВЫЗВАННЫХ ПОТЕНЦИАЛОВ НА ОСНОВЕ МНОГОМЕРНОГО ИНДЕКСА СИНХРОНИЗАЦИИ

The aim of the study is to build human-machine control systems. The main methods for con-structing such systems, methods for isolating evoked potentials in electroencephalograms. The article presents studies of electroencephalogram signals with steady state visual evoked potentials for different frequencies of photostimulation, based on the method of multivariate synchronization index. The influence of the length of the processed window on the accuracy of recognition of the frequency of the studied signal is considered. In the course of research, the authors verify the need for pre-processing of the original signals by means of bandpass signal filtering. In addition, the possibility of using a multi-dimensional synchronization index in multi-channel mode is being considered. The result of the authors study is recommendations on the parameters used to high-light the established visual evoked potentials in the method of multivariate synchronization index. The possibility of using algorithms based on a multivariate synchronization index in real time is shown. The results obtained are of practical importance, since they can be used to build neurocomputer interfaces based on visual evoked potentials and can be further used in the for-mation of control theory of robotic systems for various purposes and in the implementation of solutions for the organization of human-machine interaction in narrow practical problems.

Phase and fluorescence imaging with a surprisingly simple microscope based on chromatic aberration.

We propose a simple and compact microscope combining phase imaging with multi-color fluorescence using a standard bright-field objective. The phase image of the sample is reconstructed from a single, approximately 100 μm out-of-focus image taken under semi-coherent illumination, while fluorescence is recorded in-focus in epi-fluorescence geometry. The reproducible changes of the focus are achieved with specifically introduced chromatic aberration in the imaging system. This allows us to move the focal plane simply by changing the imaging wavelength. No mechanical movement of neither sample nor objective or any other part of the setup is therefore required to alternate between the imaging modality. Due to its small size and the absence of motorized components the microscope can easily be used inside a standard biological incubator and allows long-term imaging of cell culture in physiological conditions. A field-of-view of 1.2 mm2 allows simultaneous observation of thousands of cells with micro-meter spatial resolution in phase and multi-channel fluorescence mode. In this manuscript we characterize the system and show a time-lapse of cell culture in phase and multi-channel fluorescence recorded inside an incubator. We believe that the small dimensions, easy usage and low cost of the system make it a useful tool for biological research.

Polymer micro-lenses as an long-coupling-distance interfacing layer in low-cost optical coupling solution between optical fibers and photonic integrated waveguide circuits

We present a low-cost scheme for non-permanent optical signal coupling for prospective application in single use photonic integrated chips. The proposed scheme exploits the use of polymer kinoform microlenses. The feasibility of the proposed solution is demonstrated by the experimental investigation of the optical signal coupling from single mode optical fiber (SMF) to the test structure of SixNy integrated waveguide. Full Text: PDF ReferencesM. Smit et al., "An introduction to InP-based generic integration technology," Semiconductor Science and Technology, 29 (8), 083001, 2014 CrossRef R. Baets et al., "Silicon Photonics: silicon nitride versus silicon-on-insulator," in Optical Fiber Communication Conference, OSA Technical Digest (online) (Optical Society of America, 2016), paper Th3J.1. CrossRef K. Shiraishi et al., "A silicon-based spot-size converter between single-mode fibers and Si-wire waveguides using cascaded tapers," Appl. Phys. Lett. 91, 141120 (2007) CrossRef Y. Sobu et al., "GaInAsP/InP waveguide dual core spot size converter for optical fiber,"IEEE Photonic Society 24th Annual Meeting, 469-470, (2011). CrossRef F. Van Laere et al., "Compact and Highly Efficient Grating Couplers Between Optical Fiber and Nanophotonic Waveguides," Journal of Lightwave Technology, vol. 25, no. 1, pp. 151-156, Jan. 2007. CrossRef A. Kaźmierczak et al., "Light coupling and distribution or Si3N4/SiO2 integrated multichannel single mode sensing system," Opt. Eng. 48, 2009, pp. 014401 CrossRef M. Rossi et al., "Arrays of anamorphic phase-matched Fresnel elements for diode-to-fiber coupling," Appl. Opt. 34, 2483-2488 (1995) CrossRef M. Prasciolu et al, "Fabrication of Diffractive Optical Elements On-Fiber for Photonic Applications by Nanolitography," Japanese Journal of Applied Physics, Volume 42, (2003) CrossRef F.Schiappelli et al., "Efficient fiber-to-waveguide coupling by a lens on the end of the optical fiber fabricated by focused ion beam milling" Microelectronic Engineering Volumes 73-74, pp.397-404 (2004) CrossRef

Research on Hand Function Rehabilitation Training Device Based on Human Multimodal Sensation

Hand rehabilitation training plays a vital role in the rehabilitation of other diseases such as hand diseases and strokes. Among them, the rehabilitation and training of the fingers is an important means of hand function loss or hand disability treatment. In many sequelae of stroke, hand dysfunction is one of the most common obstacles in patients with hemiplegia after stroke, seriously affecting patients. The activities of daily life bring a heavy burden to the patients' families and society. Developed a multi-modal sensory functional rehabilitation device based on the sense of vibration, vision, and auditory multi-channel fusion mode. The physical sensory signal mobilizes the active participation of the brain in rehabilitation training, thereby effectively improving the function of finger movement after stroke. Rehabilitation effect.

Response-based multiple structural damage localization through multi-channel empirical mode decomposition

ABSTRACTExtensive research has been carried out on vibration-based structural health monitoring in the last few decades. A large number of these studies focus on response-based techniques due to its ease and efficiency. The main concern in such investigations is to extract a proper damage indicative feature from response data. This paper presents a new scheme in decomposing response data in order to extract a structural damage feature. Individual points on the structure body have their own time response signal. All these signals decomposed simultaneously through Multi-channel Empirical Mode Decomposition. Decomposed data of all structural points are put together to form a virtual structural deflection shape over time for each decomposed base vector. These time dependent deflection shapes are employed as a feature to determine damage location, if any. The proposed method was implemented both numerically and experimentally. In all cases, the proposed technique was able to locate the damaged zone successfully.

DC-Sampled Helical Fiber Grating and its Application to Multi-Channel OAM Generator

A novel DC-sampling method allowing generation of a multichannel helical long-period fiber grating (HLPG) has been proposed. Unlike the previous phase-only sampling method where phases of the continuous sampling function must be discretely adopted and inserted into the local pitches of the grating (thus high precision setups for controlling all the individual pitches of the grating are essential), the proposed method can greatly facilitate the fabrication of the multichannel HLPG by using the CO2 laser writing technique. As one typical example, the DC-sampled 3-channel HLPG has been demonstrated both theoretically and experimentally. The orbital angular momentum (OAM) modes inherently existed in this kind of HLPGs have also been verified. This is the first report for generation of a multi-channel (wavelength) OAM mode by using only one HLPG.

Imaging algorithm for multi‐channel scan synthetic aperture radar with channel error estimation and compensation

The wide swath synthetic aperture radar (SAR) imaging with a fine resolution is fundamentally a contradiction in conventional SAR imaging. To meet the demand of high-resolution width swath (HRWS) imaging, multi-channel scan mode has received a great deal of attention as a promising concept to realise HRWS observation. In this article, based on extended Chirp Scaling algorithm, an imaging algorithm for multi-channel scan SAR is proposed. Furthermore, channel error estimation and compensation are the key point in multi-channel scan imaging and are integrated into the proposed imaging algorithm. The computer simulation is shown to verify the presented imaging algorithm.

Structural damage localization through multi-channel empirical mode decomposition

PurposeThe purpose of this paper is to develop a new structural damage detection technique based on multi-channel empirical mode decomposition (MEMD) of vibrational response data.Design/methodology/approachEmpirical mode decomposition (EMD) is an empirical data-based signal decomposition method which has been applied in many engineering problems. Utilizing classical EMD to reveal the damage-indicating features of structural vibration response encounters some difficulties due to the inconsistency of modes obtained from different data channels. To overcome this problem, MEMD has been employed. To this end, MEMD algorithm has been adopted to impulse response vector of measured DOFs. The proposed method has been carried out concerning both numerical and experimental beam models. Damage has been modeled by reducing the flexural rigidity in some predefined beam sections. The effects of various factors such as measurement grid density, damage severity and damage position are investigated.FindingsThe results of both numerical and experimental case studies have been promising. The method could determine the damage location in all cases. The efficiency of method gets better when damage is located far from inflation points of the corresponding mode. In such cases, utilizing higher modes can make up the efficiency.Research limitations/implicationsSince the present research is the first investigation of MEMD in damage localization, just one-dimensional structures have been studied. Extending the method to more complicated geometries needs further attempt.Originality/valueAlthough a number of relevant studies have been carried out based on EMD, up to the author’s best knowledge, this is the first attempt to structural damage localization using MEMD.

Linear state estimation for Markov jump linear system with multi-channel observation delays and packet dropouts

ABSTRACTThis paper is to investigate the linear minimum mean square error estimation for Markovian jump linear system subject to unknown Markov chains, multi-channel mode and observation delays, and packet losses. The reorganisation method is employed to convert the delayed measurement system into an equivalent delay-free one and a new state variable is introduced, by which the original state estimation with transmission delays and data losses is transformed into the new state estimation for the reorganised delay-free system with jumping parameters and multiplicative noises. The new state estimation is derived via the innovation analysis method, and an analytical solution to the estimator is given in terms of a set of generalised Riccati difference equations based on a set of coupled Lyapunov equations. Then the original state estimation will be obtained via the jumping property. Finally, we show that the difference Riccati equations converge to a set of generalised algebraic Riccati equations under appropriate assumptions, which result in an optimal stationary filter.

Multimode silicon photonics

Abstract Multimode silicon photonics is attracting more and more attention because the introduction of higher-order modes makes it possible to increase the channel number for data transmission in mode-division-multiplexed (MDM) systems as well as improve the flexibility of device designs. On the other hand, the design of multimode silicon photonic devices becomes very different compared with the traditional case with the fundamental mode only. Since not only the fundamental mode but also the higher-order modes are involved, one of the most important things for multimode silicon photonics is the realization of effective mode manipulation, which is not difficult, fortunately because the mode dispersion in multimode silicon optical waveguide is very strong. Great progresses have been achieved on multimode silicon photonics in the past years. In this paper, a review of the recent progresses of the representative multimode silicon photonic devices and circuits is given. The first part reviews multimode silicon photonics for MDM systems, including on-chip multichannel mode (de)multiplexers, multimode waveguide bends, multimode waveguide crossings, reconfigurable multimode silicon photonic integrated circuits, multimode chip-fiber couplers, etc. In the second part, we give a discussion about the higher-order mode-assisted silicon photonic devices, including on-chip polarization-handling devices with higher-order modes, add-drop optical filters based on multimode Bragg gratings, and some emerging applications.

A Fast-Multi-Channel Sub-Millikelvin Precision Resistance Thermometer Readout Based on the Round-Robin Structure

AbstractThe fast response multipoint high-precision temperature measurement is often necessary in many dynamical measurement fields and industrial applications. However, limited by the existing electric circuit architecture, either the AC or DC bridges have the shortcoming that the rates or precisions degenerate markedly in the multi-channel scanning mode. To overcome this disadvantage, a round-robin structural low-cost ratiometric resistance thermometer readout based on several commercial 32-bit sigma-delta analogue-to-digital converters (Σ-Δ ADCs) was presented in this article. The experimental results show that the precision of this readout corresponds to 0.1 mK at 1 Hz when sampling four channel resistors simultaneously, while the precision and rate are not degenerating with the channel number increasing. In addition, the uncertainty of the readout is investigated in this article. It shows that the presented readout can achieve an uncertainty as low as 2.1 mK at 1 Hz (K = 2).

Applications of Tunable Nanoscale Midinfrared Graphene Based Slot Cavity in Nanophotonic Integrated Circuits

A graphene-based slot cavity is proposed and investigated numerically by using two-dimensional finite-difference time-domain method. The structure can be used as a tunable midinfrared multichannel bandpass filter, mode separator, multi/demultiplexer, and logic gates. Passbands of the designed filters can be tuned by varying the length and/or the chemical potential of the graphene slot cavity. The filter can be promoted to a mode separator by using another graphene output waveguide in the middle of the slot cavity filter. The even and odd order resonance modes can be separated and transmitted to the outputs. The proposed mode separator can also be used to design a wavelength multi/demultiplexer with minimum number of the slot cavities. We also proposed and simulated an ultracompact nanoscale logic gates of xor , or , and not with graphene slot cavity resonators, especially in the midinfrared wavelengths with an extinction ratio of 19.85 dB, which can be utilized for design of the nanoscale photonic integrated circuits (PICs). The gates behaviors are based on the suppression or enhancement of the resonance modes in the slot cavity due to the place of the input and output waveguide ports. These components are efficient and can be utilized in the design of midinfrared nanoscale devices and PICs.

Analysis and Design of a Multi-Channel Time-Varying Sliding Mode Controller and its Application in Unmanned Aerial Vehicles

Abstract This study introduces a new multi-channel robust nonlinear control algorithm based on the theory of the time-varying sliding mode control (TVSMC) strategy to stabilize the attitude of an unmanned aerial vehicle (UAV) for nuclear decommissioning applications. Since the UAV is imposed by constant radiations, its parameters are always time-varying and uncertain. This is particularly important in designing sliding mode control because the motion of the control system in the reaching phase can be influenced by environmental disturbances and parameter uncertainties. In this study, a time-varying sliding manifold is proposed to eliminate the reaching phase and to enhance the robust performance. Therefore, a novel type of time-varying sliding surface is introduced based on the initial condition as a slope-varying manifold. Then, a procedure for determining the control parameters is investigated. Furthermore, chattering phenomenon can be avoided using two techniques known as boundary layer and continuous SMC. Finally, to highlight the robust performance of the proposed methods, a quadrotor UAV subject to external disturbances and uncertainties is simulated.

Multi-channel scan mode and imaging algorithm for synthetic aperture ladar

The tunable band of ladar which is limited by the velocity of the laser’s tunable component contradict with the pulse repetition frequency (PRF), in SAL. Meanwhile, the swath of SAL is small for the micro-meter wavelength. This paper gives a novel imaging mode of SAL, which combines multichannel technique and Scan mode SAL. This system makes full use of information of the space domain with multichannel, and removes the ambiguity of the frequency domain in the azimuth direction. And then, controls the beam to scan in different swathes for a better width of the imaging scene, which could lead to a reasonable resolution loss. In view of the ambiguity in Scan mode, SPECAN analysis is utilized to resolve the ambiguity. Finally, the simulation proves the validity of the given method.

Multi-channel mode converter based on a modal interferometer in a two-mode fiber.

In this Letter, we propose a multi-channel mode converter with the concept of a modal interferometer in a two-mode fiber (TMF). Two lateral stress points in a TMF function as in-line fiber mode couplers to construct the modal interferometer, and both transmission spectra and near-field patterns confirm that the LP01 mode is successfully converted into an LP11 mode at the multiple channels. The measured mode conversion efficiency almost completely follows the theoretical tendency. Finally, the mode conversion is realized at 20 channels in the C+L wavelength band with conversion efficiency up to 99.5% and insertion loss as low as 0.6dB. Furthermore, the channel spacing can be freely tailored by adjusting the distance between two stress points.

Low-loss and low-crosstalk multi-channel mode (de)multiplexer with ultrathin silicon waveguides.

A multi-channel mode (de)multiplexer based on the supermode evolution in cascaded dual-core adiabatic tapers is designed and realized with ultrathin (∼50 nm) silicon-on-insulator nanowire waveguides. This dual-core adiabatic taper is designed optimally, so that all the supermodes are confined in the wide core at the input end and the highest-order supermode is localized in the narrow core at the output end. In this way, the highest-order supermode is dropped as the fundamental mode at the cross port. As an example, a (de)multiplexer with three mode channels is designed and fabricated. From the measured spectral responses, the fabricated device has a crosstalk lower than -20 dB and an excess loss less than 0.2dB in a bandwidth of ∼65 nm.

Investigation of Azimuth Multichannel Reconstruction for Moving Targets in High Resolution Wide Swath SAR.

The azimuth multichannel imaging scheme with the large receive antenna divided into multiple sub-apertures usually leads to azimuth non-uniform sampling, and echoes from all azimuth channels should be reconstructed based on the signal model before conventional SAR imaging. Unfortunately, the multichannel signal model of a moving target is different from that of a fixed target. This paper analyzes the multichannel signal model of the moving target and the effect of the target velocity on azimuth multichannel reconstruction. Based on the multichannel signal mode of the moving target, a new multichannel signal reconstruction algorithm is proposed. Furthermore, the slant range velocity is estimated by computing signal energy distribution. Simulation results on point targets validate the proposed approach.

Network Key Equipment Design Adapted to Underground Pipe Rack and Urban Energy Metering

<p style="margin: 0cm 0cm 0pt;"><span style="font-size: 12pt;" lang="EN-US"><span style="font-family: Calibri;">Traditional energy automatic metering management scheme has solved the two level problem of monitoring and application, but there is shortcoming at the transport level. Along with the advancement of industrialization and informationization, a variety of sensing devices, interconnection and unified transport demand is becoming more and more urgent. Based on FPGA platform and multichannel parallel MBUS communication mode, fusion NB - IoT technology, this paper puts forward a suitable for underground pipe rack and the network of urban energy metering design method of key equipment, it is a good way to adapt to a variety of field and meet the requirements of multiple class sensor interconnectivity unified transmission, has the very good application value.</span></span></p>

Multichannel mode conversion and multiplexing based on a single spatial light modulator for optical communication

A method is proposed to achieve multichannel mode conversion and multiplexing by dividing a single spatial light modulator into several blocks with the mode conversion pattern and blazed grating loaded on each block. The conversion patterns realize the precise excitation of higher order modes using combined amplitude and phase modulation. The blazed gratings bring together incident beams, so these beams can be coupled into few-mode fiber (FMF). In the experiment, four higher order modes are precisely excited and converge with a tilt angle. Through the simulation method, these beams can be coupled into FMF with small tilt angles (0.0344 deg for LP 11 mode).