The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer fro...The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer from numerical overflow or underflow when the Bessel function’s order is large,the argument is small or the argument has a large imaginary part.The first two issues have been solved recently by employing small-argument asymptotic formulas of Bessel functions,while the third issue remains unsolved.In this paper,the Bessel functions in the conventional formulation of the theory are replaced by scaled Bessel functions which have good numerical properties for high loss media,and stable formulas are derived.Numerical tests show that this approach can work properly with very high lossy media.Also,this approach can be seamlessly combined with the stable computation method for cases of small argument and large order of Bessel functions.展开更多
In the context of high compression rates applied to Joint Photographic Experts Group(JPEG)images through lossy compression techniques,image-blocking artifacts may manifest.This necessitates the restoration of the imag...In the context of high compression rates applied to Joint Photographic Experts Group(JPEG)images through lossy compression techniques,image-blocking artifacts may manifest.This necessitates the restoration of the image to its original quality.The challenge lies in regenerating significantly compressed images into a state in which these become identifiable.Therefore,this study focuses on the restoration of JPEG images subjected to substantial degradation caused by maximum lossy compression using Generative Adversarial Networks(GAN).The generator in this network is based on theU-Net architecture.It features a newhourglass structure that preserves the characteristics of the deep layers.In addition,the network incorporates two loss functions to generate natural and high-quality images:Low Frequency(LF)loss and High Frequency(HF)loss.HF loss uses a pretrained VGG-16 network and is configured using a specific layer that best represents features.This can enhance the performance in the high-frequency region.In contrast,LF loss is used to handle the low-frequency region.The two loss functions facilitate the generation of images by the generator,which can mislead the discriminator while accurately generating high-and low-frequency regions.Consequently,by removing the blocking effects frommaximum lossy compressed images,images inwhich identities could be recognized are generated.This study represents a significant improvement over previous research in terms of the image resolution performance.展开更多
An equivalent-circuit model is used to analyse the improvement of the wave absorbing performance of the lossy frequency selective surface（FSS） absorber by using a magnetic substrate,showing that it is possible to wi...An equivalent-circuit model is used to analyse the improvement of the wave absorbing performance of the lossy frequency selective surface（FSS） absorber by using a magnetic substrate,showing that it is possible to widen the wave absorbing bandwidth.Three pieces of magnetic substrates are prepared.According to the complex permittivity and permeability,the reflectivity of the corresponding absorber is calculated by the finite difference time-domain（FDTD） method,and the bandwidth of the reflectivity below 10 dB is optimized by genetic algorithm.The calculated results indicate that the wave absorbing performance is significantly improved by increasing the complex permeability of the substrate;the reflectivity bandwidth below 10 dB of the single layer FSS absorber can reach 3.6-18 GHz with a thickness of 5 mm,which is wider than that with a dielectric substrate.The density of the FSS absorber is only 0.92 g/cm 3.Additionally,the absorption band can be further widened by inserting a second lossy FSS.Finally,a double layer lossy FSS absorber with a magnetic substrate is fabricated based on the design result.The experimental result is consistent with the design one.展开更多
Information freshness is a key factor for Internet-of-Things(IoT)to make appropriate decisions and operations.This paper proposes an analytical framework for evaluating the timeliness performance of the IoT system bas...Information freshness is a key factor for Internet-of-Things(IoT)to make appropriate decisions and operations.This paper proposes an analytical framework for evaluating the timeliness performance of the IoT system based on Unmanned Aerial Vehicle(UAV)lossy communications.The performance analysis consists of the outage probability analysis and the Age-of-Information(AoI)analysis with outages.To begin with,we solve a lossy coding problem formulated from the UAV communication system,and derive a closed-form expression of the outage probability based on Shannon's lossy source-channel separation theorem.Then,we characterize the Peak AoI(PAoI)for the considered system,and further minimize the PAoI by deriving the optimal rate for generating information.Moreover,we analyze the system performance through theoretical calculations and simulations.The results indicate that the optimal server utilization ratio is always no larger than 0.5.In practical applications,we can utilize the proposed analytical framework to determine the system parameters which guarantee the timeliness performance of UAV lossy communications.展开更多
Periodic dielectric-loaded waveguide is one of the diaphragmatic waveguides. For the excellent mode-selective propagation ability, it is of value for applications in gyrotron-traveling-wave amplifiers （gyro-TWT）, ac...Periodic dielectric-loaded waveguide is one of the diaphragmatic waveguides. For the excellent mode-selective propagation ability, it is of value for applications in gyrotron-traveling-wave amplifiers （gyro-TWT）, accelerators, and other microwave propagation systems. This paper focuses on studying the application of the strong lossy-dielectric- loaded periodic waveguide in millimeter-wave gyro-TWT. It is revealed that due to the lossy property of the dielectric, the energy in the dielectric slots is absorbed effectively and the high order Bloch harmonics induced by the periodicity of the structure are suppressed, which changes the discrete spectrum under losstess condition into a continuous one. As a result, the periodicity of the system is severely suppressed and a mode in the hollow region could be approximated by a fast wave mode in an empty waveguide. These results bring specific guidance for the applications of the lossy dielectric-loaded waveguide in gyro-TWTs and other devices.展开更多
In the terahertz band,the dispersive characteristic of dielectric material is one of the major problems in the scaled radar cross section(RCS)measurement,which is inconsistent with the electrodynamics similitude deduc...In the terahertz band,the dispersive characteristic of dielectric material is one of the major problems in the scaled radar cross section(RCS)measurement,which is inconsistent with the electrodynamics similitude deducted according to the Maxwell’s equations.Based on the high-frequency estimation method of physical optics(PO),a scaled RCS measurement method for lossy objects is proposed through dynamically matching the reflection coefficients according to the distribution of the object facets.Simulations of the model of SLICY are conducted,and the inversed RCS of the lossy prototype is obtained using the proposed method.Comparing the inversed RCS with the calculated results,the validity of the proposed method is demonstrated.The proposed method provides an effective solution to the scaled RCS measurement for lossy objects in the THz band.展开更多
Formulas of diffraction field of lossy wedges with less than 180?wedge angle are derived on the basis of the Fresnel-Kirchhoff wave theory and their numerical results are compared with those of the heuristic lossy wed...Formulas of diffraction field of lossy wedges with less than 180?wedge angle are derived on the basis of the Fresnel-Kirchhoff wave theory and their numerical results are compared with those of the heuristic lossy wedge diffraction coefficient given by Luebbers (1984), showing good agreement between the two types of numerical results which have different bases in theory. The agreement shows that the lossy wedge diffraction coefficient as an extension of UTD is quite reasonable.展开更多
A hybrid algorithm is presented for nonuniform lossy multiconductor transmission lines (MTL) connected by arbitrary linear load networks. The networks are characterized by a state-variable equation which allows a gene...A hybrid algorithm is presented for nonuniform lossy multiconductor transmission lines (MTL) connected by arbitrary linear load networks. The networks are characterized by a state-variable equation which allows a general characterization of dynamic elements in the cascade networks. The method is achieved by the finite difference-time domain (FDTD) algorithm for the MTL, and the skin effect is taken into account, the more accurate method is used to compute the skin effect. And this method is combined with the computation of the nonuniform transmission lines. Finally, several numerical examples are given, these results indicate that: the current of the lossy MTL is smaller than the lossless of the MTL; and when the load networks contain the dynamic element, the transition time of the current is longer than the MTL connected by resistance only.展开更多
The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutr...The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutral equation is reduced. Sufficient conditions for the existence and uniqueness of periodic regimes are formulated. The proof is based on the finding out of suitable operator whose fixed point is a periodic solution of the neutral equation. The method has a good rate of convergence of the successive approximations even for high frequencies.展开更多
In this paper, we present a spatio-temporal post-processing error concealment (EC) algorithm designed initially for a H.264 video-streaming scheme over packet-lossy networks. It aims at optimizing the subjective quali...In this paper, we present a spatio-temporal post-processing error concealment (EC) algorithm designed initially for a H.264 video-streaming scheme over packet-lossy networks. It aims at optimizing the subjective quality of the restored video under the constraints of low delay and computational complexity, which are critical to real-time applications and portable devices having limited resources. Specifically, it takes into consideration the physical property of motion field in order to achieve more meaningful perceptual video quality, in addition to the improved objective PSNR. Further, a simple bilinear spatial interpolation approach is combined with the improved boundary-match (B-M) based temporal EC approach according to texture and motion activity analysis. Finally, we propose a low complexity temporal EC method based on motion vector interpolation as a replacement of the B-M based approach in the scheme under low-computation requirement, or as a complement to further improve the scheme's performance in applications having enough computation resources. Extensive experiments demonstrated that the proposal features not only better reconstruction, objectively and subjectively, than JM benchmark, but also robustness to different video sequences.展开更多
In this paper,the electromagnetic scattering of plane wave with TM and TEpolarizations from a lossy dielectric cylinder with arbitrary cross section is analyzed andcomputed by using the boundary element method.The num...In this paper,the electromagnetic scattering of plane wave with TM and TEpolarizations from a lossy dielectric cylinder with arbitrary cross section is analyzed andcomputed by using the boundary element method.The numerical results of scattering pat-tern for a circular cylinder completely coincide with the analytical solution and that of thescattering properties in the near-or far-field region for elliptical and regular triangularcylinders are presented,which point out some valuable conclusions.展开更多
A lossy mode resonance(LMR)-supported fiber optic sensor in which a uniform fiber core is placed among two identical tapered regions, is investigated numerically. Indium tin oxide(ITO)and aluminum-doped zinc oxide(AZO...A lossy mode resonance(LMR)-supported fiber optic sensor in which a uniform fiber core is placed among two identical tapered regions, is investigated numerically. Indium tin oxide(ITO)and aluminum-doped zinc oxide(AZO) are considered as LMR active materials used to excite several lossy modes and gold and silver are used as surface plasmon resonance(SPR) active materials. In this probe design, a central uniform core coated with ITO/AZO is the active sensing region, whereas tapered regions are meant for bringing the incident angle close to the critical angle. The sensitivity of the present fiber optic bio-sensor is evaluated for first two LMRs utilizing both ITO and AZO separately, along with its variation with the taper ratio(TR). For ITO, the maximum sensitivity values are observed to be 18.425 μm RIU^(-1)(refractive index unit)and 0.825 μm RIU^(-1), corresponding to the first and second LMRs, respectively, at a TR of 1.6 and for AZO, equivalent values are 0.79 μm RIU^(-1) and 0.35 μm RIU^(-1), respectively, at a TR of2.0. The results illustrate that the first LMR is more sensitive than the second LMR and the ITOcoated probe possesses greater sensitivity than the AZO-coated probe for both LMRs. Similarly,for the fiber optic SPR sensor, the maximum value of sensitivity is 5.6425 μm RIU^(-1), in the case of gold and 5.0615 μm RIU^(-1) in the case of silver, at a TR of 1.6. Hence, the result shows that the sensor with the present fiber optic probe design has around a 3-fold enhancement in sensitivity compared with conventional SPR sensors. This study will have applications in many sensing schemes where the requirement of large sensitivity is vital.展开更多
The problem for calculating EM energy absorption by lossy dielectric scatterer ir-radiated by plane wave are discussed.The factors affecting the accuracy of computation arediscussed.The calculated results of EM energy...The problem for calculating EM energy absorption by lossy dielectric scatterer ir-radiated by plane wave are discussed.The factors affecting the accuracy of computation arediscussed.The calculated results of EM energy absorption and its distribution in homogeneousand layered homogenous lossy dielectric spheres are presented,and a comparison of these resultswith analytical solution is given.The calculation is carried out for dielectric cylinder on conduct-ing ground as well,and the results are compared with the image theory.All the computationsshew that the finite-difference time-domain method can give satisfactory results.展开更多
The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical...The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical results show the effects of tthe input impedance, which could be used in designing the Cavity-Backed Slot Antenna展开更多
A method for computing DC steady-state solutions in complex frequency-domain is put forward. It starts with complex frequency-domain transmission line equations, obtains the complex expressions of voltage and current ...A method for computing DC steady-state solutions in complex frequency-domain is put forward. It starts with complex frequency-domain transmission line equations, obtains the complex expressions of voltage and current at zero initial states, and find the DC steady-state solutions of voltage and current by using the fina value theorem of Laplace transform thory. The solutions are discussed with special internal resistances of DC voltage source and loads. A case study demonstrated that the proposed method is applicable to acquiring the DC steady-state voltage waveform and current waveform without first obtaining the analytic solutions.展开更多
This paper presents a passive monitoring mechanism, loss）, nodes inference （LoNI）, to identify loss）, nodes in wireless sensor network using end-to-end application traffic. Given topology dynamics and bandwidth co...This paper presents a passive monitoring mechanism, loss）, nodes inference （LoNI）, to identify loss）, nodes in wireless sensor network using end-to-end application traffic. Given topology dynamics and bandwidth constraints, a space-efficient packet marking scheme is first introduced. The scheme uses a Bloom filter as a compression tool so that path information can bc piggybacked by data packets. Based on the path information, LoNI then adopts a fast algorithm to detect lossy nodes. The algorithm formulates the inference problem as a weighted set-cover problem and solves it using a greedy approach with low complexity. Simulations show that LoNI can locate about 80% of lossy nodes when lossy nodes are rare in the network. Furthermore, LoNI performs better for the lossy nodes near the sink or with higher loss rates.展开更多
NeEative refraction at the interface between air and a lossy plasma layer is theoretically analyzed based on the inhomogeneous wave theory. The phenomenon of negative refraction, which arises from the negative refract...NeEative refraction at the interface between air and a lossy plasma layer is theoretically analyzed based on the inhomogeneous wave theory. The phenomenon of negative refraction, which arises from the negative refraction angle, can occur when a transverse magnetic wave is incident from air to the lossy plasma layer under certain conditions. The formula of the negative refraction angle is derived, and the dependences of the negative refraction angle on the angle of incidence, frequency of incidence, and lossy plasma layer are analytically investigated. The parameter dependences of the effects are calculated and discussed.展开更多
The start-oscillation-current of a gyro-TWT (gyrotron traveling-wave tube) determines the stable operating current level of the device. The amplifier is susceptible to oscillations when the operating current level is ...The start-oscillation-current of a gyro-TWT (gyrotron traveling-wave tube) determines the stable operating current level of the device. The amplifier is susceptible to oscillations when the operating current level is higher than the start-oscillation current. There are several ways of calculating the start-oscillation current, including using the linear and nonlinear theory of a gyro-TWT. In this paper, a simple way of determining the start-oscillation current of lossy gyro-TWT is introduced. The linear TWT parameters that include the effects of synchronism, loss, and gain, were converted to gyro-TWT parameters to calculate the start-oscillation-current. The dependence on magnetic field, loss, and beam alpha was investigated. Calculations were carried out for a V-band gyro-TWT for both operating and competing modes. The proposed method of calculating the start-oscillation current provides a simple and fast way to estimate the oscillation conditions and can be used for the design process of a gyro-TWT.展开更多
This work presents a novel current-mode (CM) lossless integrator that uses one current differencing differential input transconductance amplifier (CDDITA) and one grounded capacitor. The configuration based on single ...This work presents a novel current-mode (CM) lossless integrator that uses one current differencing differential input transconductance amplifier (CDDITA) and one grounded capacitor. The configuration based on single active element has several advantages from the aspect of monolithic integration, few are: reduced power consumption, chip miniaturization. Employment of grounded capacitor is also beneficial for monolithic integration. Specifying some of the key features of integrator proposed are: 1) purely resistorless, 2) electronically tunable, 3) current output available at the port having high impedance, and 4) excellent performance under non-ideal conditions. So, a resister-less current mode lossy integrator with electronic control employing single CDDITA has been proposed in this paper. The verification of workability of the proposed current mode integrator is well explained by the help of SPICE simulations using TSMC CMOS 0.18 μm technology node.展开更多
Image compression techniques aim to reduce redundant information in order to allow data storage and transmission in an efficient way. In this work, we propose and analyze a lossy image compression method based on the ...Image compression techniques aim to reduce redundant information in order to allow data storage and transmission in an efficient way. In this work, we propose and analyze a lossy image compression method based on the singular value decomposition using an optimal choice of eigenvalues and an adaptive mechanism for block partitioning. Experiments are conducted on several images to demonstrate the effectiveness of the proposed compression method in comparison with the direct application of the singular value decomposition.展开更多
文摘The spherically layered media theory has wide applications for electromagnetic wave scattering analysis.Due to the involved Bessel functions,the conventional formulations of spherically layered media theory suffer from numerical overflow or underflow when the Bessel function’s order is large,the argument is small or the argument has a large imaginary part.The first two issues have been solved recently by employing small-argument asymptotic formulas of Bessel functions,while the third issue remains unsolved.In this paper,the Bessel functions in the conventional formulation of the theory are replaced by scaled Bessel functions which have good numerical properties for high loss media,and stable formulas are derived.Numerical tests show that this approach can work properly with very high lossy media.Also,this approach can be seamlessly combined with the stable computation method for cases of small argument and large order of Bessel functions.
基金supported by the Technology Development Program(S3344882)funded by the Ministry of SMEs and Startups(MSS,Korea).
文摘In the context of high compression rates applied to Joint Photographic Experts Group(JPEG)images through lossy compression techniques,image-blocking artifacts may manifest.This necessitates the restoration of the image to its original quality.The challenge lies in regenerating significantly compressed images into a state in which these become identifiable.Therefore,this study focuses on the restoration of JPEG images subjected to substantial degradation caused by maximum lossy compression using Generative Adversarial Networks(GAN).The generator in this network is based on theU-Net architecture.It features a newhourglass structure that preserves the characteristics of the deep layers.In addition,the network incorporates two loss functions to generate natural and high-quality images:Low Frequency(LF)loss and High Frequency(HF)loss.HF loss uses a pretrained VGG-16 network and is configured using a specific layer that best represents features.This can enhance the performance in the high-frequency region.In contrast,LF loss is used to handle the low-frequency region.The two loss functions facilitate the generation of images by the generator,which can mislead the discriminator while accurately generating high-and low-frequency regions.Consequently,by removing the blocking effects frommaximum lossy compressed images,images inwhich identities could be recognized are generated.This study represents a significant improvement over previous research in terms of the image resolution performance.
文摘An equivalent-circuit model is used to analyse the improvement of the wave absorbing performance of the lossy frequency selective surface（FSS） absorber by using a magnetic substrate,showing that it is possible to widen the wave absorbing bandwidth.Three pieces of magnetic substrates are prepared.According to the complex permittivity and permeability,the reflectivity of the corresponding absorber is calculated by the finite difference time-domain（FDTD） method,and the bandwidth of the reflectivity below 10 dB is optimized by genetic algorithm.The calculated results indicate that the wave absorbing performance is significantly improved by increasing the complex permeability of the substrate;the reflectivity bandwidth below 10 dB of the single layer FSS absorber can reach 3.6-18 GHz with a thickness of 5 mm,which is wider than that with a dielectric substrate.The density of the FSS absorber is only 0.92 g/cm 3.Additionally,the absorption band can be further widened by inserting a second lossy FSS.Finally,a double layer lossy FSS absorber with a magnetic substrate is fabricated based on the design result.The experimental result is consistent with the design one.
基金supported by the National Natural Science Foundation of China(NSFC)(No.62001387)Shanghai Academy of Spaceflight Technology(SAST),China(No.SAST2020124).
文摘Information freshness is a key factor for Internet-of-Things(IoT)to make appropriate decisions and operations.This paper proposes an analytical framework for evaluating the timeliness performance of the IoT system based on Unmanned Aerial Vehicle(UAV)lossy communications.The performance analysis consists of the outage probability analysis and the Age-of-Information(AoI)analysis with outages.To begin with,we solve a lossy coding problem formulated from the UAV communication system,and derive a closed-form expression of the outage probability based on Shannon's lossy source-channel separation theorem.Then,we characterize the Peak AoI(PAoI)for the considered system,and further minimize the PAoI by deriving the optimal rate for generating information.Moreover,we analyze the system performance through theoretical calculations and simulations.The results indicate that the optimal server utilization ratio is always no larger than 0.5.In practical applications,we can utilize the proposed analytical framework to determine the system parameters which guarantee the timeliness performance of UAV lossy communications.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 60871051,60871047 and 60971072)
文摘Periodic dielectric-loaded waveguide is one of the diaphragmatic waveguides. For the excellent mode-selective propagation ability, it is of value for applications in gyrotron-traveling-wave amplifiers （gyro-TWT）, accelerators, and other microwave propagation systems. This paper focuses on studying the application of the strong lossy-dielectric- loaded periodic waveguide in millimeter-wave gyro-TWT. It is revealed that due to the lossy property of the dielectric, the energy in the dielectric slots is absorbed effectively and the high order Bloch harmonics induced by the periodicity of the structure are suppressed, which changes the discrete spectrum under losstess condition into a continuous one. As a result, the periodicity of the system is severely suppressed and a mode in the hollow region could be approximated by a fast wave mode in an empty waveguide. These results bring specific guidance for the applications of the lossy dielectric-loaded waveguide in gyro-TWTs and other devices.
基金supported by the National Natural Science Foundation of China(Grant Nos.61871386,61971427,62035014,and 61921001)the Natural Science Fund for Distinguished Young Scholars of Hunan Province,China(Grant No.2019JJ20022)。
文摘In the terahertz band,the dispersive characteristic of dielectric material is one of the major problems in the scaled radar cross section(RCS)measurement,which is inconsistent with the electrodynamics similitude deducted according to the Maxwell’s equations.Based on the high-frequency estimation method of physical optics(PO),a scaled RCS measurement method for lossy objects is proposed through dynamically matching the reflection coefficients according to the distribution of the object facets.Simulations of the model of SLICY are conducted,and the inversed RCS of the lossy prototype is obtained using the proposed method.Comparing the inversed RCS with the calculated results,the validity of the proposed method is demonstrated.The proposed method provides an effective solution to the scaled RCS measurement for lossy objects in the THz band.
文摘Formulas of diffraction field of lossy wedges with less than 180?wedge angle are derived on the basis of the Fresnel-Kirchhoff wave theory and their numerical results are compared with those of the heuristic lossy wedge diffraction coefficient given by Luebbers (1984), showing good agreement between the two types of numerical results which have different bases in theory. The agreement shows that the lossy wedge diffraction coefficient as an extension of UTD is quite reasonable.
文摘A hybrid algorithm is presented for nonuniform lossy multiconductor transmission lines (MTL) connected by arbitrary linear load networks. The networks are characterized by a state-variable equation which allows a general characterization of dynamic elements in the cascade networks. The method is achieved by the finite difference-time domain (FDTD) algorithm for the MTL, and the skin effect is taken into account, the more accurate method is used to compute the skin effect. And this method is combined with the computation of the nonuniform transmission lines. Finally, several numerical examples are given, these results indicate that: the current of the lossy MTL is smaller than the lossless of the MTL; and when the load networks contain the dynamic element, the transition time of the current is longer than the MTL connected by resistance only.
文摘The paper deals with a lossy transmission line terminated at both ends by non-linear RCL elements. The mixed problem for the hyperbolic system, describing the transmission line, to an initial value problem for a neutral equation is reduced. Sufficient conditions for the existence and uniqueness of periodic regimes are formulated. The proof is based on the finding out of suitable operator whose fixed point is a periodic solution of the neutral equation. The method has a good rate of convergence of the successive approximations even for high frequencies.
基金Project supported by the Teaching and Research Award Program for Outstanding Young Professor in High Education Institute, Ministration of Education, China
文摘In this paper, we present a spatio-temporal post-processing error concealment (EC) algorithm designed initially for a H.264 video-streaming scheme over packet-lossy networks. It aims at optimizing the subjective quality of the restored video under the constraints of low delay and computational complexity, which are critical to real-time applications and portable devices having limited resources. Specifically, it takes into consideration the physical property of motion field in order to achieve more meaningful perceptual video quality, in addition to the improved objective PSNR. Further, a simple bilinear spatial interpolation approach is combined with the improved boundary-match (B-M) based temporal EC approach according to texture and motion activity analysis. Finally, we propose a low complexity temporal EC method based on motion vector interpolation as a replacement of the B-M based approach in the scheme under low-computation requirement, or as a complement to further improve the scheme's performance in applications having enough computation resources. Extensive experiments demonstrated that the proposal features not only better reconstruction, objectively and subjectively, than JM benchmark, but also robustness to different video sequences.
文摘In this paper,the electromagnetic scattering of plane wave with TM and TEpolarizations from a lossy dielectric cylinder with arbitrary cross section is analyzed andcomputed by using the boundary element method.The numerical results of scattering pat-tern for a circular cylinder completely coincide with the analytical solution and that of thescattering properties in the near-or far-field region for elliptical and regular triangularcylinders are presented,which point out some valuable conclusions.
基金the Department of Science and Technology (DST),INDIA for providing the INSPIRE fellowship (Registration No.-IF170543)。
文摘A lossy mode resonance(LMR)-supported fiber optic sensor in which a uniform fiber core is placed among two identical tapered regions, is investigated numerically. Indium tin oxide(ITO)and aluminum-doped zinc oxide(AZO) are considered as LMR active materials used to excite several lossy modes and gold and silver are used as surface plasmon resonance(SPR) active materials. In this probe design, a central uniform core coated with ITO/AZO is the active sensing region, whereas tapered regions are meant for bringing the incident angle close to the critical angle. The sensitivity of the present fiber optic bio-sensor is evaluated for first two LMRs utilizing both ITO and AZO separately, along with its variation with the taper ratio(TR). For ITO, the maximum sensitivity values are observed to be 18.425 μm RIU^(-1)(refractive index unit)and 0.825 μm RIU^(-1), corresponding to the first and second LMRs, respectively, at a TR of 1.6 and for AZO, equivalent values are 0.79 μm RIU^(-1) and 0.35 μm RIU^(-1), respectively, at a TR of2.0. The results illustrate that the first LMR is more sensitive than the second LMR and the ITOcoated probe possesses greater sensitivity than the AZO-coated probe for both LMRs. Similarly,for the fiber optic SPR sensor, the maximum value of sensitivity is 5.6425 μm RIU^(-1), in the case of gold and 5.0615 μm RIU^(-1) in the case of silver, at a TR of 1.6. Hence, the result shows that the sensor with the present fiber optic probe design has around a 3-fold enhancement in sensitivity compared with conventional SPR sensors. This study will have applications in many sensing schemes where the requirement of large sensitivity is vital.
文摘The problem for calculating EM energy absorption by lossy dielectric scatterer ir-radiated by plane wave are discussed.The factors affecting the accuracy of computation arediscussed.The calculated results of EM energy absorption and its distribution in homogeneousand layered homogenous lossy dielectric spheres are presented,and a comparison of these resultswith analytical solution is given.The calculation is carried out for dielectric cylinder on conduct-ing ground as well,and the results are compared with the image theory.All the computationsshew that the finite-difference time-domain method can give satisfactory results.
文摘The characteristics of a cavity-backed using the moment method and Dyadic Green's funused to convert the double series of the elements inintegration middle value theorem and elliptic integr}the elements. Numerical results show the effects of tthe input impedance, which could be used in designing the Cavity-Backed Slot Antenna
文摘A method for computing DC steady-state solutions in complex frequency-domain is put forward. It starts with complex frequency-domain transmission line equations, obtains the complex expressions of voltage and current at zero initial states, and find the DC steady-state solutions of voltage and current by using the fina value theorem of Laplace transform thory. The solutions are discussed with special internal resistances of DC voltage source and loads. A case study demonstrated that the proposed method is applicable to acquiring the DC steady-state voltage waveform and current waveform without first obtaining the analytic solutions.
文摘This paper presents a passive monitoring mechanism, loss）, nodes inference （LoNI）, to identify loss）, nodes in wireless sensor network using end-to-end application traffic. Given topology dynamics and bandwidth constraints, a space-efficient packet marking scheme is first introduced. The scheme uses a Bloom filter as a compression tool so that path information can bc piggybacked by data packets. Based on the path information, LoNI then adopts a fast algorithm to detect lossy nodes. The algorithm formulates the inference problem as a weighted set-cover problem and solves it using a greedy approach with low complexity. Simulations show that LoNI can locate about 80% of lossy nodes when lossy nodes are rare in the network. Furthermore, LoNI performs better for the lossy nodes near the sink or with higher loss rates.
基金Supported by the National Natural Science Foundation of China under Grant No 11205119the Fundamental Research Funds for the Central Universities of China under Grant No WUT:2014-Ia-009
文摘NeEative refraction at the interface between air and a lossy plasma layer is theoretically analyzed based on the inhomogeneous wave theory. The phenomenon of negative refraction, which arises from the negative refraction angle, can occur when a transverse magnetic wave is incident from air to the lossy plasma layer under certain conditions. The formula of the negative refraction angle is derived, and the dependences of the negative refraction angle on the angle of incidence, frequency of incidence, and lossy plasma layer are analytically investigated. The parameter dependences of the effects are calculated and discussed.
文摘The start-oscillation-current of a gyro-TWT (gyrotron traveling-wave tube) determines the stable operating current level of the device. The amplifier is susceptible to oscillations when the operating current level is higher than the start-oscillation current. There are several ways of calculating the start-oscillation current, including using the linear and nonlinear theory of a gyro-TWT. In this paper, a simple way of determining the start-oscillation current of lossy gyro-TWT is introduced. The linear TWT parameters that include the effects of synchronism, loss, and gain, were converted to gyro-TWT parameters to calculate the start-oscillation-current. The dependence on magnetic field, loss, and beam alpha was investigated. Calculations were carried out for a V-band gyro-TWT for both operating and competing modes. The proposed method of calculating the start-oscillation current provides a simple and fast way to estimate the oscillation conditions and can be used for the design process of a gyro-TWT.
文摘This work presents a novel current-mode (CM) lossless integrator that uses one current differencing differential input transconductance amplifier (CDDITA) and one grounded capacitor. The configuration based on single active element has several advantages from the aspect of monolithic integration, few are: reduced power consumption, chip miniaturization. Employment of grounded capacitor is also beneficial for monolithic integration. Specifying some of the key features of integrator proposed are: 1) purely resistorless, 2) electronically tunable, 3) current output available at the port having high impedance, and 4) excellent performance under non-ideal conditions. So, a resister-less current mode lossy integrator with electronic control employing single CDDITA has been proposed in this paper. The verification of workability of the proposed current mode integrator is well explained by the help of SPICE simulations using TSMC CMOS 0.18 μm technology node.
文摘Image compression techniques aim to reduce redundant information in order to allow data storage and transmission in an efficient way. In this work, we propose and analyze a lossy image compression method based on the singular value decomposition using an optimal choice of eigenvalues and an adaptive mechanism for block partitioning. Experiments are conducted on several images to demonstrate the effectiveness of the proposed compression method in comparison with the direct application of the singular value decomposition.
