Robust state-space realizations of digital filters against finite word length errors

This article deals with two important issues in digital filter implementation： roundoff noise and limit cycles. A novel class of robust state-space realizations, called normal realizations, is derived and characterized. It is seen that these realizations are free of limit cycles. Another interesting property of the normal realizations is that they yield a minimal error propagation gain. The optimal realization problem, defined as to find those normal realizations that minimize roundoff noise gain, is formulated and solved analytically. A design example is presented to demonstrate the behavior of the optimal normal realizations and to compare them with several well-known digital filter realizations in terms of minimizing the roundoff noise and the error propagation.

Sensing and lasing applications of whispering gallery mode microresonators

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.

The BOLS-NEP theory reconciling the attributes of undercoordinated adatoms,defects,surfaces and nanostructures

This article describes a theory unifying the unusual performance of the undercoordinated adatoms,point defects,terrace edges,surfaces,and nanostructures of various shapes.The ideas of bond order-length-strength correlation and the associated nonbonding electron polarization(BOLS-NEP)feature that bonds between undercoordinated atoms contract spontaneously.Bond contraction raises the local density of charge and energy.Bond strength gain deepens the interatomic potential well to trap the core and bonding electrons deeply.In turn,the locally and densely entrapped electrons polarize those partially occupying the valence band and above pertaining to the lower-coordinated atoms.The BOLS-NEP theory reconciles the unusual behaviors of undercoordinated systems and the size dependency of nanostructures in their lattice oscillating dynamics,mechanical strength,thermal stability,photon emissivity,chemical reactivity,dielectric permeability,associated with generation of polarized Dirac fermions,serving as carriers for extraordinary catalysis,hydrophobicity,fluidity,lubricity,as well as monolayer high-TC superconductivity and topological insulator conductivity.

Meta-Heuristic Optimized Hybrid Wavelet Features for Arrhythmia Classification

The non-invasive evaluation of the heart through EectroCardioG-raphy(ECG)has played a key role in detecting heart disease.The analysis of ECG signals requires years of learning and experience to interpret and extract useful information from them.Thus,a computerized system is needed to classify ECG signals with more accurate results effectively.Abnormal heart rhythms are called arrhythmias and cause sudden cardiac deaths.In this work,a Computerized Abnormal Heart Rhythms Detection(CAHRD)system is developed using ECG signals.It consists of four stages;preprocessing,feature extraction,feature optimization and classifier.At first,Pan and Tompkins algorithm is employed to detect the envelope of Q,R and S waves in the preprocessing stage.It uses a recursive filter to eliminate muscle noise,T-wave interference and baseline wander.As the analysis of ECG signal in the spatial domain does not provide a complete description of the signal,the feature extraction involves using frequency contents obtained from multiple wavelet filters;bi-orthogonal,Symlet and Daubechies at different resolution levels in the feature extraction stage.Then,Black Widow Optimization(BWO)is applied to optimize the hybrid wavelet features in the feature optimization stage.Finally,a kernel based Support Vector Machine(SVM)is employed to classify heartbeats into five classes.In SVM,Radial Basis Function(RBF),polynomial and linear kernels are used.A total of∼15000 ECG signals are obtained from the Massachusetts Institute of Technology-Beth Israel Hospital(MIT-BIH)arrhythmia database for performance evaluation of the proposed CAHRD system.Results show that the proposed CAHRD system proved to be a powerful tool for ECG analysis.It correctly classifies five classes of heartbeats with 99.91%accuracy using an RBF kernel with 2nd level wavelet coefficients.The CAHRD system achieves an improvement of∼6%over random projections with the ensemble SVM approach and∼2%over morphological and ECG segment based features with the RBF classifier.

权值光滑BP算法:一种改善网络推广性能的方法

推广性能是人工神经网络研究的重要方向。在推广性能的研究中，改进学习算法是提高前向网络推广性能的重要方法之一。本文对一种特殊的权值光滑BP算法的理论基础进行了仔细的研究，并将该算法首次应用于水声目标的分类问题。实验结果表明，具有权值光滑BP算法的前向网络不仅具有较光滑的连接权值，而且其推广性能也优于具有标准BPM算法的前向网络。

Advances in Conceptual Electronic Nanodevices based on 0D and 1D Nanomaterials

Nanoelectronic devices are being extensively developed in these years with a large variety of potential applications. In this article, some recent developments in nanoelectronic devices, including their principles, structures and potential applications are reviewed. As nanodevices work in nanometer dimensions, they consume much less power and function much faster than conventional microelectronic devices. Nanoelectronic devices can operate in different principles so that they can be further grouped into field emission devices,molecular devices, quantum devices, etc. Nanodevices can function as sensors, diodes, transistors, photovoltaic and light emitting devices, etc. Recent advances in both theoretical simulation and fabrication technologies expedite the development process from device design to prototype demonstration. Practical applications with a great market value from nanoelectronic devices are expected in near future.

Rules essential for water molecular undercoordination

A sequential of concepts developed in the last decade has enabled a resolution to multiple anomalies of water ice and its low-dimensionality,particularly.Developed concepts include the coupled hydrogen bond(O:H–O)oscillator pair,segmental specific heat,three-body coupling potentials,quasisolidity,and supersolidity.Resolved anomalies include ice buoyancy,ice slipperiness,water skin toughness,supercooling and superheating at the nanoscale,etc.Evidence shows consistently that molecular undercoordination shortens the H–O bond and stiffens its phonon while undercoordination does the O:H nonbond contrastingly associated with strong lone pair“:”polarization,which endows the low-dimensional water ice with supersolidity.The supersolid phase is hydrophobic,less dense,viscoelastic,thermally more diffusive,and stable,having longer electron and phonon lifetime.The equal number of lone pairs and protons reserves the configuration and orientation of the coupled O:H–O bonds and restricts molecular rotation and proton hopping,which entitles water the simplest,ordered,tetrahedrally-coordinated,fluctuating molecular crystal covered with a supersolid skin.The O:H–O segmental cooperativity and specific-heat disparity form the soul dictate the extraordinary adaptivity,reactivity,recoverability,and sensitivity of water ice when subjecting to physical perturbation.It is recommended that the premise of“hydrogen bonding and electronic dynamics”would deepen the insight into the core physics and chemistry of water ice.

Secret Image Communication Scheme Based on Visual Cryptography and Tetrolet Tiling Patterns

Visual cryptographic scheme is specially designed for secret image sharing in the form of shadow images.The basic idea of visual cryptography is to construct two or more secret shares from the original image in the form of chaotic image.In this paper,a novel secret image communication scheme based on visual cryptography and Tetrolet tiling patterns is proposed.The proposed image communication scheme will break the secret image into more shadow images based on the Tetrolet tiling patterns.The secret image is divided into 4×4 blocks of tetrominoes and employs the concept of visual cryptography to hide the secret image.The main feature of the proposed scheme is the selection of random blocks to apply the tetrolet tilling patterns from the fundamental tetrolet pattern board.Single procedure is used to perform both tetrolet transform and the scheme of visual cryptography.Finally,the experimental results showcase the proposed scheme is an extraordinary approach to transfer the secret image and reconstruct the secret image with high visual quality in the receiver end.

Design of Deep Reinforcement Learning Controller Through Data-assisted Model for Robotic Fish Speed Tracking

It is common for robotic fish to generate thrust using reactive force generated by the tail’s physical motion, which interacts with the surrounding fluid. The coupling effect of the body strongly correlates with this thrust. However, hydrodynamics cannot be wholly modeled in analytical form. Therefore, data-assisted modeling is necessary for robotic fish. This work presents the first method of its kind using Genetic Algorithm (GA)-based optimization methods for data-assistive modeling for robotic fish applications. To begin, experimental data are collected in real time with the robotic fish that has been designed and fabricated using 3D printing. Then, the model’s influential parameters are estimated using an optimization problem. Further, a model-based deep reinforcement learning (DRL) controller is proposed to track the desired speed through extensive simulation work. In addition to a deep deterministic policy gradient (DDPG), a twin delayed DDPG (TD3) is employed in the training of the RL agent. Unfortunately, due to its local optimization problem, the RL-DDPG controller failed to perform well during training. In contrast, the RL-TD3 controller effectively learns the control policies and overcomes the local optima problem. As a final step, controller performance is evaluated under different disturbance conditions. In contrast to DDPG and GA-tuned proportional-integral controllers, the proposed model with RL-TD3 controller significantly improves the performance.

Polarization-maintaining few mode fiber composed of a central circular-hole and an elliptical-ring core

We propose a novel waveguide design of polarization-maintaining few mode fiber(PM-FMF) supporting ≥10non-degenerate modes, utilizing a central circular air hole and a circumjacent elliptical-ring core. The structure endows a new degree of freedom to adjust the birefringence of all the guided modes, including the fundamental polarization mode. Numerical simulations demonstrate that, by optimizing the air hole and elliptical-ring core,a PM-FMF supporting 10 distinctive polarization modes has been achieved, and the effective index difference Δn_(eff) between the adjacent guided modes could be kept larger than 1.32 × 10^(-4) over the whole C +L band. The proposed fiber structure can flexibly tailored to support an even larger number of modes in PM-FMF(14-mode PM-FMF has been demonstrated as an example), which can be readily applicable to a scalable mode division multiplexing system.

Naive Bayesian classifier for hydrophobicity classification of overhead polymeric insulators using binary image features with ambient light compensation

Dispersion nature of water droplets over the insulator surface is used for hydrophobicity classification.Stochastic nature of water dispersions makes naive Bayesian classifier a preferable choice,which has been investigated in this work.About 12 features describing the characteristics of water droplets are extracted from the binary image using binary large objects analysis.Ambient light intensity is a significant factor that affects the binary image quality.As these insulators are installed in the outside environment,variations in ambient light intensity are inevitable.An adaptive threshold technique is proposed to compensate for ambient light variations.Six classes of various ambient light intensities have been considered in this study,and the proposed adaptive threshold technique can produce quality binary image consistently.Features extracted from the binary image are ordered according to their principal components(PCs)using PC analysis.Improvement in classification accuracy with the accumulation of ordered features is analysed.Results illustrate the use of the first eight features provides a reliable classification accuracy of 97.6%for test image samples.In comparison to the other existing classifiers,the proposed classifier illustrates optimal performance in terms of classification accuracy and computational time.

Economical evaluation of large-scale photovoltaic systems using Universal Generating Function techniques

Solar energy plays an important role in the global energy framework for future.Comparing with conventional generation systems using fossil fuels,the cost structure of photovoltaic(PV)systems is different:the capital cost is higher while the operation cost is negligible.Reliabilities of the PV system can also influence the cost for producing electricity.Investors,planners and regulators require deep insight into the return and cost of a PV project.A reliability based economical assessment of largescale PV systems has been conducted utilizing Universal Generating Function(UGF)techniques.The reliability models of solar panel arrays,PV inverters and energy production units(EPUs)are represented as the corresponding UGFs.The expected energy production models for different PV system configurations have also been developed.The expected unit cost of electricity has been calculated to provide informative metrics for making optimal decisions.The proposed method has been applied to determine the PV system configuration which provides electricity for a water purification process.

Risk analysis of power systems for both real and reactive power

With the high penetration of renewable energy sources,the reliability of power systems becomes more vulnerable than ever because of the greater uncertainty and intermittence in power generation.Reactive power plays an important role in the power system reliability,because it is closely related to the system voltage stability and voltage collapse.However,reactive power-related reliability issues are seldom emphasized in conventional power reliability evaluations.This article investigates power system reliability of real and reactive power.Real and reactive power shortages and the associated voltage violations due to system failures are considered on reliability evaluation of power systems.A three-stage load-shedding technique for post contingencies is implemented to determine the contributions of real and reactive power on the system reliability and to find an optimal way to release network violation.The results provide the detailed information on power system planning and operation for system planners and operators from real and reactive power aspects.

From ice superlubricity to quantum friction: Electronic repulsivity and phononic elasticity

Superlubricity means non-sticky and frictionless when two bodies are set contacting motion.Although this occurrence has been extensively investigated since 1859 when Faraday firstly proposed a quasiliquid skin on ice,the mechanism behind the superlubricity remains uncertain.This report features a consistent understanding of the superlubricity pertaining to the slipperiness of ice,self-lubrication of dry solids,and aqueous lubricancy from the perspective of skin bond-electron-phonon adaptive relaxation.The presence of nonbonding electron polarization,atomic or molecular undercoordination,and solute ionic electrification of the hydrogen bond as an addition,ensures the superlubricity.Nonbond vibration creates soft phonons of high magnitude and low frequency with extraordinary adaptivity and recoverability of deformation.Molecular undercoordination shortens the covalent bond with local charge densification,which in turn polarizes the nonbonding electrons making them localized dipoles.The locally pinned dipoles provide force opposing contact,mimicking magnetic levitation and hovercraft.O:H−O bond electrification by aqueous ions has the same effect of molecular undercoordination but it is throughout the entire body of the lubricant.Such a Coulomb repulsivity due to the negatively charged skins and elastic adaptivity due to soft nonbonding phonons of one of the contacting objects not only lowers the effective contacting force but also prevents charge from being transited between the counterparts of the contact.Consistency between theory predictions and observations evidences the validity of the proposal of interface elastic Coulomb repulsion that serves as the rule for the superlubricity of ice,wet and dry frictions,which also reconciles the superhydrophobicity,superlubricity,and supersolidity at contacts.

基于无线传感器网络的分散目标跟踪:实际测试平台的开发应用(英文)

In the real world,centralized tracking in a large-scale wireless sensor network (WSN) may not be feasible due to the possible failure of fusion centre and the large communication delay in forwarding measurement data to the fusion centre. Distributed target tracking techniques can be employed by tasking sensor nodes near to the target to perform sensing,target state estimation and selection of future tasking sensor nodes. In this paper,the development and implementation of a prototype ultrasonic WSN test-bed to demonstrate distributed target tracking using the Extended Kalman Filter (EKF) algorithm is described. In the test-bed,a mobile robot is used to simulate the moving target,and static/mobile sensor nodes are deployed to detect and track the target. The sensor nodes and robots are equipped with sonar and MICAZ to receive and process instructions. Experimental evaluation of a number of sensor scheduling schemes are reported which shows the superior tracking performance of our distributed competition based sensor scheduling scheme.

Translucent Optical Networks Design for Static Traffic

A routing and wavelength assignment algorithm is proposed to minimize the number of wavelengths and transceivers required simultaneously under static traffic in translucent optical networks design.