COVERAGE PERFORMANCES ANALYSIS ON COMBINED-GEO-IGSO SATELLITE CONSTELLATION

The Combined-GEO-IGSO constellation is the combination of Geostationary Earth Orbit(GEO) satellite and Inclining GeoSynchronous Orbit(IGSO) satellite.The Combined-GEO-IGSO constellation can integrate the advantages of GEO and IGSO to achieve regional coverage.In order to discuss the performances of the Combined-GEO-IGSO constellation,the performances of coverage,elevation,diversity,and transmission are simulated in China and surrounding regions by Satellite Tool Kit(STK).The simulation results show that:the combined constellation can reach higher multi-satellite coverage and higher communication elevation in China and surrounding areas;the Doppler shift,delay,and propagation loss of this constellation have little impact on the system.As regional coverage constellation,the Combined-GEO-IGSO is feasible.

A NOVEL ALGORITHM OF MULTI-SENSOR IMAGE FUSION BASED ON WAVELET PACKET TRANSFORM

In order to enhance the image information from multi-sensor and to improve the abilities of the information analysis and the feature extraction, this letter proposed a new fusion approach in pixel level by means of the Wavelet Packet Transform (WPT). The WPT is able to decompose an image into low frequency band and high frequency band in higher scale. It offers a more precise method for image analysis than Wavelet Transform (WT). Firstly, the proposed approach employs HIS (Hue, Intensity, Saturation) transform to obtain the intensity component of CBERS (China-Brazil Earth Resource Satellite) multi-spectral image. Then WPT transform is employed to decompose the intensity component and SPOT (Systeme Pour I'Observation de la Therre ) image into low frequency band and high frequency band in three levels. Next, two high frequency coefficients and low frequency coefficients of the images are combined by linear weighting strategies. Finally, the fused image is obtained with inverse WPT and inverse HIS. The results show the new approach can fuse details of input image successfully, and thereby can obtain a more satisfactory result than that of HM (Histogram Matched)-based fusion algorithm and WT-based fusion approach.

KERNEL NEIGHBORHOOD PRESERVING EMBEDDING FOR CLASSIFICATION

The Neighborhood Preserving Embedding(NPE) algorithm is recently proposed as a new dimensionality reduction method.However, it is confined to linear transforms in the data space.For this, based on the NPE algorithm, a new nonlinear dimensionality reduction method is proposed, which can preserve the local structures of the data in the feature space.First, combined with the Mercer kernel, the solution to the weight matrix in the feature space is gotten and then the corresponding eigenvalue problem of the Kernel NPE(KNPE) method is deduced.Finally, the KNPE algorithm is resolved through a transformed optimization problem and QR decomposition.The experimental results on three real-world data sets show that the new method is better than NPE, Kernel PCA(KPCA) and Kernel LDA(KLDA) in performance.

Quorum systems for intrusion-tolerance based on trusted timely computing base

Quorum systems have been used to solve the problem of data consistency in distributed fault-tolerance systems. But when intrusions occur, traditional quorum systems have some disadvantages. For example, synchronous quorum systems are subject to DOS attacks, while asynchronous quorum systems need a larger system size （at least 3f＋1 for generic data, and f fewer for self-verifying data）. In order to solve the problems above, an intrusion-tolerance quorum system （ITQS） of hybrid time model based on trust timely computing base is presented （TTCB）. The TTCB is a trust secure real-time component inside the server with a well defined interface and separated from the operation system. It is in the synchronous communication environment while the application layer in the server deals with read-write requests and executes update-copy protocols asynchronously. The architectural hybridization of synchrony and asynchrony can achieve the data consistency and availability correctly. We also build two kinds of ITQSes based on TTCB, i.e., the symmetrical and the asymmetrical TTCB quorum systems. In the performance evaluations, we show that TTCB quorum systems are of smaller size, lower load and higher availability.

Research and Implementation of Architecture for Distributed Service Performance Management

An architecture for online discovery quantitative models system of service performance management is proposed. The system is capable of constructing the quantitative models without prior knowledge of the managed elements. The model can be updated continuously in response to the changes made in provider configurations and the evolution of business demands. Due to the existence of strong correlation between the distributed service metrics and response times, linear and hyper-linear quantitative models are constructed, which respectively, use stepwise multiple linear regression algorithm. The simulation results show the effectiveness of a quantitative model constructing system and model constructing algorithms.

THE NUMERICAL SOLUTIONS OF CUT-OFF FREQUENCIES IN TWO-DIELECTRIC LAYERED WAVEGUIDE BY USING BOUNDARY ELEMENT METHOD

This paper diseusses the general principle of finding the cut-off frequencies in two-dielectric lay-ered waveguides by using the boundary element method,based on the fundamental solution of a twodimensional Helmholtz equation.In terms of the formulae given in the paper,some numerical resultsare obtained for two commonly used configurations.The fimal results show that the method is of an appre-ciable precision.

Research on phase-detecting method for coherent combining beams in fiber laser array

A novel method for phase-detecting of each individual beam in coherent beam combining system of fiber laser array based on the property of time-shift of fast Fourier transform is reported. It takes advantage of the relative movement of fringepattern to detect the phase shift between each individual beam and reference beam. No frequency shift component for reference beam is required in the system. At the same time, the acquisition fringe-pattern is firstly tailored to a few multiple of fringes in order to reduce the phase-detecting error caused by energy leakage during the course of fast Fourier transform. This technique can greatly reduce the effect of energy leakage and thus improve the phase-detecting precision. Basic principle of the new phase-detecting method is described in detail, and numerical results show that the phase-detecting error is less than 1/1000 wavelength bv utilizing our method.

EFFECTIVE MEDIUM THEORY OF MULTIPHASE MIXTURE AND SELECTIVE ABSORPTION OF ELECTROLYTICALLY COLORED ANODIC ALUMINUM OXIDE

The effective medium theory is extended to multiphase mixture,and a corresponding formula of effective complex dielectric permittivity is derived.An electrolytically colored anodic aluminum oxide is regarded as a multilayer absorption composite,and the reflectances of Au-Cu-Al_(2)O_(3) and Ag-Cu-Al_(2)O_(3) coatings have been measured.

SIMULATION AND ANALYSIS OF PERFORMANCE ON THE COMPASSTM ENHANCED BY GEO AND IGSO

Positioning accuracy of the Global Navigation Satellite System(GNSS) can be analyzed by Positioning Dilution Of Precision(PDOP).In order to enhance the navigating performance of Asia and the Pacific areas,this paper analyzes the next generation BeidouTM navigation satellite system(CompassTM) enhanced by Geostationary Earth Orbit(GEO) and Inclining GeoSynchronized Orbit(IGSO).As global navigation satellite system,CompassTM must be robust enough to avoid system layoff,when some nodes are not available.So,the CompassTM enhanced by GEO and IGSO constellation is proposed and analyzed its PDOP proformance,this paper shows some exciting results of performance of CompassTM enhanced by GEO and IGSO.From the simulation results,we can found that:when more than fifteen satellites are invalid,the enhanced system could be operating normally.

Switched-Beam Optimization for an Indoor Visible Light Communication Using Genetic Algorithm

Nowadays, Visible Light Communication (VLC) is an attractivealternative technology for wireless communication because it can use somesimple Light Emitting Diodes (LEDs) instead of antennas. Typically, indoorVLC is designed to transmit only one dataset through multiple LED beams at atime. As a result, the number of users per unit of time (throughput) is relativelylow. Therefore, this paper proposes the design of an indoor VLC system usingswitched-beam technique through computer simulation. The LED lamps aredesigned to be arranged in a circular array and the signal can be transmittedthrough the beam of each LED lamp with the method of separating the datasetto increase the number of simultaneous users for enhancing the indoor VLC.The coverage area is determined from the area where the communication canbe performed at a location on the receiving plane with a Bit Error Rate lessthan or equal to the specified value based on coverage illuminance accordingto International Commission on Illumination (CIE) standards. In this paper,Genetic Algorithm is used to find the suitable solution for designing parameters to achieve maximum coverage area. The results show that a GeneticAlgorithm can be used to find a suitable solution and reduce the computationaltime approximately 382 min in proposed scenarios.

MODULE SHARING(?)ESIGN TECHNIQUE FOR DUAL REFLECTOR ANTENNA

Module sharing technique for a dual reflector antenna is presented,which makes different aper-tured main reflectors of the same focus sharing one set of module by means of optimizing the subreflector.To optimize the subreflector,a fast convergence optimization method is given with a satisfactory result.

An Optimal Lifetime Utility Routing for 5G and Energy-Harvesting Wireless Networks

Harvesting energy from environmental sources such as solar and wind can mitigate or solve the limited-energy problem in wireless sensor networks. In this paper, we propose an energy-harvest-aware route-selection method that incorporates harvest availability properties and energy storage capacity limits into the routing decisions. The harvest-aware routing problem is formulated as a lin- ear program with a utility-based objective function that balances the two conflicting routing objectives of maximum total and maxi- mum minimum residual network energy. The simulation results show that doing so achieves a longer network lifetime, defined as the time-to-first-node-death in the network. Additionally, most existing energy-harvesting routing algorithms route each traffic flow independently from each other. The LP formulation allows for a joint optimization of multiple trafic flows. Better residual energy statistics are also achieved by such joint consideration compared to independent optimization of each commodity.

A Circularly Polarized Sector Antenna for Mobile Base Station Using Single Feed with Metallic Rod EBG

The propose of this paper is to design the circularly polarized antenna for mobile base station, using a curved strip dipole associated with U-shaped reflector and multi-layer metallic rod elec-tromagnetic band gap (EBG). It can be used to simplify the single feed system of an antenna. The advantages of this proposed antenna are easy fabrication and installation, high gain and light weight. Moreover, it provides a sectoral radiation pattern, a main beam having a narrow beam width in the vertical direction and wider beamwidth in the horizontal direction, which are appro-priate for mobile phone base station. The half-power beam in the H-plane and E-plane are 60 and 14.4 degrees, respectively. The antenna is designed and analyzed by using a computer simulation technology (CST). In addition, S11, axial ratio, radiation pattern and gain are displayed. The designed technique could be confirmed by a measurement resulting from prototype antenna corresponding to simulation results. The proposed antenna has a bandwidth covering the frequency range of 1870 - 2170 MHz, and the gain of the antenna increases up to 15.11 dBi.

A Sector Antenna for Mobile Base Station Using MSA Array with Curved Woodpile EBG

This paper presents a sector antenna for base station of mobile phone using microstrip antenna (MSA) array with curved woodpile Electromagnetic Band Gap (EBG). The advantages of this pro- posed antenna are easy fabrication and installation, high gain, and light weight. Moreover, it pro- vides a fan-shaped radiation pattern , a main beam having a narrow beam width in the vertical di- rection and a wider beamwidth in the horizontal direction, which are appropriate for mobile phone base station. The half-power beamwidths in the H-plane and E-plane are 37.4 and 8.7 de- grees, respectively. The paper also presents the design procedures of a 1 × 8 array antenna using MSAs associated with U-shaped reflector for decreasing their back and side lobes. A Computer Si- mulation Technology (CST) software has been used to compute the reflection coefficient (S11), radiation patterns, and gain of this antenna. The bandwidth, at S11 (?10 dB), is enough, which can be well utilized for 3G base station, with a gain 20.84 dB.

Review on Identity-Based Batch Verification Schemes for Security and Privacy in VANETs

The study of vehicular ad-hoc networks(VANETs)has received significant attention among academia;even so,its security and privacy still become a central issue that is wide-open to discuss.The authentication schemes deployed in VANETs have a substantial impact on its security and privacy.Many researchers have proposed a variety of schemes related to the information verification and efficiency improvement in VANETs.In recent years,many papers have proposed identity-based batch verification(IBV)schemes in regard to diminishing overhead in the message verification process in VANETs.This survey begins with providing background information about VANETs and clarifying its security and privacy,as well as performance requirements that must be satisfied.After presenting an outlook of some relevant surveys of VANETs,a brief review of some IBV schemes published in recent years is conferred.The detailed approach of each scheme,with a comprehensive comparison between them,has been provided afterward.Finally,we summarize those recent studies and possible future improvements.

Lower-Limb Motion-Based Ankle-Foot Movement Classification Using 2D-CNN

Recently,the Muscle-Computer Interface(MCI)has been extensively popular for employing Electromyography(EMG)signals to help the development of various assistive devices.However,few studies have focused on ankle foot movement classification considering EMG signals at limb position.This work proposes a new framework considering two EMG signals at a lower-limb position to classify the ankle movement characteristics based on normal walking cycles.For this purpose,we introduce a human anklefoot movement classification method using a two-dimensional-convolutional neural network(2D-CNN)with low-cost EMG sensors based on lowerlimb motion.The time-domain signals of EMG obtained from two sensors belonging to Dorsiflexion,Neutral-position,and Plantarflexion are firstly converted into time-frequency spectrograms by short-time Fourier transform.Afterward,the spectrograms of the three ankle-foot movement types are used as input to the 2D-CNN such that the EMG foot movement types are finally classified.For the evaluation phase,the proposed method is investigated using the healthy volunteer for 5-fold cross-validation,and the accuracy is used as a standard evaluation.The results demonstrate that our approach provides an average accuracy of 99.34%.This exhibits the usefulness of 2D-CNN with low-cost EMG sensors in terms of ankle-foot movement classification at limb position,which offers feasibility for walking.However,the obtained EMG signal is not directly considered at the ankle position.

Nonlinearity modelling of an on-board microwave photonics system based on Mach-Zehnder modulator

For the nonlinearity distortion problem of Mach-Zehnder modulator(MZM)applied in the on-board microwave photonics system,the situation for two input radio frequency(RF)signals with different frequencies and phases is discussed,and an exact analytical solution is derived with the method of expanding Bessel series and Graf addition theory.According to the analytical expression,the nonlinearity characteristics of the modulator can be precisely predicted,and the system performance can be optimized.The correctness of the analytical solution is approved by simulation results.Analytical results indicate that the nonlinearity distortion is suppressed as the decrease of modulation index,the increase of direct current bias phase shift and phase difference between two input RF signals.When the phase difference equals zero orπand the direct current bias phase shift isπ/2,there are only odd-order distortion terms.When the phase difference equals zero orπand the direct current bias phase shift isπ,there are only even-order distortion terms.

A LIMITED ORDER CAPACITY STOCHASTIC INVENTORY MODEL WITH A FIXED COST FOR ORDER: THE DISCOUNTED CASE

This paper considers a single-item, periodic-review inventory model with linear ordercosts, a convex function representing expected one-period costs, nonegative i.i.d. demandsand a fixed cost for order. Stockouts are backordered. All data are stationary Both finiteand infinite horizon problems are treated.

Influence of phase shift drift and splitting ratio on 80 GHz optical mm-wave generation

For the scheme of 80 GHz optical millimeter-wave(mm-wave) generation using two cascaded Mach-Zehnder modulators(MZMs),an exact analytical solution for the optical mm-wave affected by phase shift drift and splitting ratio is derived with the method of expanding Bessel series.The results show that for the carrier and the fourth-order sideband,the influence caused by phase shift drift is dominant,while the first-order,the second-order and the third-order sidebands are influenced by both phase shift drift and splitting ratio.It follows that the undesired sideband suppression ratio is at least 35.9 dB when the splitting ratio deviation is 0.001,and the phase shift drift is 1o.The performance of the system is perfect if the accuracy is achieved.

Experimental research on spatial filtering of deformed laser beam by transmitting volume Bragg grating

Using transmitting volume Bragg gratings （TVBG） as a basis,an experiment on one-dimensional spatial filtering of a deformed laser beam is designed.The deformed laser beam results from a He-Ne laser beam modulated by an amplitude modulation plate with a spatial frequency of 7.2 mm·1.Results show that when the central wave vector of the deformed beam satisfies the Bragg law of TVBG,the spatial profile of the -1st forward-diffracted order is similar to that of the undeformed He-Ne laser beam due to the TVBG with a spatial frequency selective bandwidth of less than 5.0 mm·1.The higher frequency components of the deformed beam are filtered out in the optical near field.Thus,the TVBG cleanup of the spatiallydeformed laser beam is realized experimentally.