摘要：The synchrotron radiation spectra of the spherical grating monochromator (SGM) working in the soft X-ray and VUV region are often contaminated by significant amounts of higher order harmonics. They cannot be suppressed completely by suitable filters. Higher order contributions in the spectral radiation standard and metrology beamline were researched using transmission grating (made in-house) and IRD AXUV100G (USA) photodiode detector. The exit beam was dispersed with the transmission grating behind the exit slit of the monochromator, and the contributions of the different orders were analyzed. The higher order distributions were quantitatively determined for three gratings with line densities of 1800, 600 and 200 l/mm.Experiment results show that in wavelengths between 5 nm and 15 nm the contributions of the higher orders to the detector signal are restricted to less than 7% even without the use of filters. In wavelength regions between 5 nm and 34 nm, the contributions of the higher orders to the detector signal are less than 14% with proper Al, Si3N4 and Zr filters, and after being modified by quantum efficiency of the detector, the higher order contributions are restricted to less than 6.5%. The study also shows that higher orders are almost totally suppressed by MgF2 filter when the wavelength ranges between 115-140 nm.
摘要：Ultra-shallow Si p+n junctions formed by plasma doping are characterized by electrochemical capacitance-voltage (ECV). By comparing ECV results with those of secondary ion mass spectroscopy (SIMS), it is found that the dopant concentration profiles in heavily-doped p+ layer as well as junction depths measured by ECV are in good agreement with those measured by SIMS. However, the ECV measurement of dopant concentration in the underlying lightly doped n-type substrate is significantly influenced by the upper heavily-doped layer. The ECV technique is also easy to control and reproduce. The ECV results of ultra-shallow junctions (US J) formed by plasma doping followed by different annealing processes show that ECV is capable of reliably characterizing a Si USJ with junction depth as low as 10 nm, and dopant concentration up to 1021 cm-3. Also, its depth resolution can be as fine as 1 nm. Therefore, it shows great potential in application for characterizing USJ in the sub-65 nm technology node CMOS devices.
摘要：Rotation, scaling and translation (RST) attacks can desynchronize watermark detection, which causes failure in many watermarking systems. In this paper, an image adaptive RST invariant watermark (AWPZM) is proposed by using the rotation invariant property of pseudo-Zernike moments (PZM) and odd-even quantization. PZM of the original image is computed first, and then those suitable for watermark generation are selected. Then, magnitudes of them are odd-even quantized to generate the watermark. In detection, a normalized hamming function is employed to determine the similarity of the watermark. Experimental results show its robustness to rotation and scaling. For traditional attacks, such as JPEG compression, added noise and filtering, the similarities are all above 0.95.
摘要：Many recently proposed subspace clustering methods suffer from two severe problems. First, the algorithms typically scale exponentially with the data dimensionality or the subspace dimensionality of clusters. Second, the clustering results are often sensitive to input parameters. In this paper, a fast algorithm of subspace clustering using attribute clustering is proposed to over-come these limitations. This algorithm first filters out redundant attributes by computing the Gini coefficient. To evaluate the correlation of every two non-redundant attributes, the relation matrix of non-redundant attributes is constructed based on the relation function of two dimensional united Gini coefficients. After applying an overlapping clustering algorithm on the relation matrix, the candidate of all interesting subspaces is achieved. Finally, all subspace clusters can be derived by clustering on interesting subspaces. Experiments on both synthesis and real datasets show that the new algorithm not only achieves a significant gain of runtime and quality to find subspace clusters, but also is insensitive to input parameters.
摘要：The magnetic field distribution of an emission antenna is studied in this paper. When the slenderness ratio of the emission antenna is high, the emission antenna can be simplified as a magnetic dipole for practical application. The numerical results of the magnetic dipole magnetic field show that the magnetic magnitude dis-tribution has a hump-shape, whose direction is perpendi-cular with the antenna axis direction. A localization method based on the hump-shape signal detection is presented. The experimental result shows that the preci-sion can reach a value of + 5 cm. The method can be used to localize a pipeline robot working in a metal pipe.
摘要：By using Mie's theory, the boundary condi-tions, and some advanced mathematical knowledge, the scattering problem of a plane-wave by bi-sphere groups and of cores-traversed coherent Gauss-beams by one sphere was addressed. In each, the coefficients of the scattering-field expressions were deduced. Finally, the result was predigested and transfigured so that the available form for programming was achieved. On deducing, the former adopted the undetermined coeffi-cient method and the latter used the plane geometry method. Moreover, the complexity of the calculation was decreased here.
摘要：This is our first report on the high perfor-mance 1 mm AlGaN/GaN high electron mobility tran-sistor (HEMT) which was developed using home-made AlGaN/GaN epitaxy structures based on SiC substrate. Metal-organic chemical vapor deposition (MOCVD) was used to generate the epitaxy layers. Corresponding experiments show that the device has a gate length of 0.8 μm exhibiting drain current density of 1.16 A/mm, transconductance of 241 ms/mm, a gate-drain break-down voltage larger than 80 V, maximum current gain frequency of 20 GHz and maximum power gain frequency of 28 GHz. In addition, the power gain under the continues wave condition is 14.2 dB with a power density of 4.1 W/mm, while under the pulsed wave condition, power gain reaches 14.4 dB with power density at 5.2 W/mm. Furthermore, the two-port net-work impedance characteristics display great potential in microwave application.
摘要：Through analyzing the theoretical spreading principle,it has been proved in this paper that the benefit of pseudo-orthogonal carrier interferometry(PO-CI)spreading code is not supported when complex signal modulation(e.g.,quadrature phase-shift keying(QPSK)and quadrature amplitude modulation(QAM))types are employed.On this basis,a novel and feasible structure for this problem is brought forward.Within the structure mentioned,instead of complex modulation patterns,pulse amplitude modulation(PAM)combined with PO-CI spreading code is utilized.This allows us to maintain the throughput increase of a multi-carrier code division multiple access(MC-CDMA)system with minimal loss in performance and no bandwidth expansion.
摘要：To deal with long probing delay and inaccurate probing results in the endpoint admission control method,a joint local and end-to-end admission control algorithm is proposed,which introduces local probing of access network besides end-to-end probing.Through local probing,the algorithm accurately estimated the resource status of the access network.Simulation shows that this algorithm can improve admission control performance and reduce users' average waiting time when the access network is heavily loaded.
摘要：This paper proposes a technique of image content authentication based on the Laplacian Pyramid to verify the authenticity of image content.First,the image is decomposed into Laplacian Pyramid before the transformation.Next,the smooth and detail properties of the original image are analyzed according to the Laplacian Pyramid,and the properties are classified and encoded to get the corresponding characteristic values.Then,the signature derived from the encrypted characteristic values is embedded in the original image as a watermark.After the reception,the characteristic values of the received image are compared with the watermark drawn out from the image.The algorithm automatically identifies whether the content is tampered by means of morphologic filtration.The information of tampered location is Presented at the same time.Experimental results show that the pro posed authentication algorithm can effectively detect the event and location when the original image content is tampered.Moreover,it can tolerate some distortions produced by compression,filtration and noise degradation.
摘要：The design of the gain-scheduled H2H∞ filter for polytopic discrete-time systems is investigated.By introducing additional slack variables,a new mixed H2/H∞ performance criterion is proposed,which provides a decoupling between the Lyapunov matrix and system matrices.Based on the new performance criterion,a sufficient condition for the existence of the gain-scheduled H2/H∞ filter is derived.Furthermore,the filter design problem is converted into a convex optimization problem with linear matrix inequality(LMI)constraints.Simulation results show the effectiveness of the proposed approach.
摘要：SQL injection poses a major threat to the application level security of the database and there is no systematic solution to these attacks.Different from traditional run time security strategies such as IDS and fire wall,this paper focuses on the solution at the outset;it presents a method to find vulnerabilities by analyzing the source codes.The concept of validated tree is developed to track variables referenced by database operations in scripts.By checking whether these variables are influenced by outside inputs,the database operations are proved to be secure or not.This method has advantages of high accuracy and efficiency as well as low costs,and it is universal to any type of web application platforms.It is implemented by the SOftware code vulnerabilities of SQL injection detector(CVSID).The validity and efficiency are demonstrated with an example.
摘要：Based on Chameleon Hash and D.Boneh's one round multi-party key agreement protocol,this paper proposes a multi-designated verifiers signature scheme.In this scheme only the verifiers designated by the signer can independently verify the signature.And no one else other than the designated person can be convinced by this signature even if one of the designated verifiers reveals the secret value.The analysis of the proposed scheme shows that it satisfies non-transferability,unforgeability and privacy of the signer's identity and has to low computational cost.
摘要：A peer-to-peer hierarchical replica location mechanism(PRLM)was designed for data grids to provide better load balancing capability and scalability.Global replica indexes of the PRLM are organized based on even distributed Chord(ED-Chord)structure.The locality can optimize queries on local replica indexes of virtual organizations.ED-Chord protocol collects the node identifiers information using a distributed method and assigns optimal identifiers for new nodes to make them more uniformly distributed in the entire identifier space.Theoretical analysis and simulations show that PRLM provides good performance,scalability and load balancing capability for replica location in data grids.
摘要：In this paper,we propose a new directional multi-resolution ridgelet network(DMRN)based on the ridgelet frame theory,which uses the ridgelet as the activation function in a hidden layer.For the multi-resolution properties of the ridgelet function in the direction besides scale and position.DMRN has great capabilities in catching essential features of direction-rich data.It proves to be able to approximate any multivariate function in a more stable and efficient way,and optimal in approximating functions with spatial inhomogeneities.Besides,using binary ridgelet frame as the mathematical foundation in its construction,DMRN is more flexible with a simple structure.The construction and the learning algorithm of DMRN are given.Its approximation capacity and approximation rate are also analyzed in detail.Possibilities of applications to regression and recognition are included to demonstrate its superiority to other methods and feasibility in practice.Both theory analysis and simulation results prove its high efficiency.
摘要：The definitions and properties of widely used fractional-order derivatives are summarized in this paper.The characteristic polynomials of the fractional order systems are pseudo-polynomials whose powers of the complex variable are non-integers.This kind of systems can be approximated by high-order integer-order systems,and can be analyzed and designed by the sophisticated integer-order systems methodology.A new closed-form algorithm for fractional-order linear differential equations is proposed based on the definitions of fractional-order derivatives,and the effectiveness of the algorithm is illustrated through examples.
摘要：Identification of the optimal operating conditions and evaluation of their robustness are critical issues for industrial processes.A standard procedure,for modelling a laboratory-scale wire-to-cylinder electrostatic precipitator and for guiding the research of the set point,is presented.The procedure consists of formulating a set of recommendations regarding the choice of parameter values for electrostatic precipitation.The experiments were carried out on a laboratory cylindrical precipitator,built by one of the authors,with samples of wood particles.The parameters considered are the applied high voltage U,the air flow F,and the quantity of dust in air m.Several"one-factor-at-a-time"followed by factorial composite design experiments were performed,based on the following three-step strategy:1)Identify the domain of variation of the variables;2)Determine the mathematical model of the process outcome:3)Validation of the mathematical model and optimisation of the process.
摘要：Based on an appropriate Lyapunov function,this paper analyzes the design of a delay-dependent robust H∞ state feedback control,with a focus on a class of non linear uncertainty linear time-delay systems with input delay using linear matrix inequalities.Under the condition that the nonlinear uncertain functions are gain bounded,a sufficient condition dependent on the delays of the state and input is presented for the existence of H∞ controller.The proposed controller not only stabilized closed-loop uncertain systems but also guaranteed a prescribed H∞ norm bound of closed-loop transfer matrix from the disturbance to controlled output.By solving a linear matrix inequation,we can obtain the robust H∞ controller.An example is given to show the effectiveness of the proposed method.
摘要：An improved susceptible-infected-susceptible(SIS)model in the local-world evolving network model is presented to study the epidemic spreading behavior with time delay,which is added into the infected phase.The local-world evolving model displays a transition from the exponential network to the scale-free network with respect to the degree distribution.Two typical delay regimes,i.e.,uniform and degree-dependent delays are incorporated into the SIS epidemic model to investigate the epidemic infection processes in the local-world network model.The results indicate that the infection delay will promote the epidemic outbreaks,increase the prevalence and reduce the critical threshold of epidemic spreading.It is also found that local-world size M will considerably influence the epidemic spreading behavior with time delay in the local-world network through large-scale numerical simulations.Simulation results are also of relevance to fight epidemic outbreaks.
摘要：Recent developments of the ultra-wideband(UWB)planar antennas are reviewed,where the progress in UWB plate monopole antennas,UWB printed monopole antennas and the UWB printed slot antennas is introduced and compared.In addition,the UWB printed antennas with the band-notched functions are also presented.
摘要：A multi-image wavelet transform motion estimation algorithm based on gradient methods is presented by using the characteristic of wavelet transfom.In this algorithm,the accuracy can be improved greatly using data in many images to measure motions between two images.In combination with the reliability measure for constraints function,the reliable data constraints of the images were decomposed with multi-level simultaneous wavelet transform rather than the traditional coarse-to-fine approach.Compared with conventional methods,this motion measurement algorithm based on multi-level simultaneous wavelet transform avoids propagating errors between the decomposed levels.Experimental simulations show that the implementation of this algo rithm is simple,and the measurement accuracy is improved.
摘要：The end-to-end delay of protective relaying data flow in a substation was studied by dynamic simulation modeling technology.The distribution characteristics of protective relaying data flow and the constitution of the end-to-end delay of messages were analyzed.The simulation model for digital communication between protective relaying equipment and monitoring equipment of interval layer was suggested.The end-to-end delay of protective relaying data flow in different network configurations was analyzed.It is found that the size and interval of the data frame,utilization of the link background and protocols of higher layer are key factors of real-time performance,Detailed analysis results are presented.A proposal for network configuration is suggested to reduce end-to-end delay of protective relaying data flow.
摘要：A novel scheme for extracting the global scattering center model of radar targets is proposed in this paper.The 2D/3D scattering center models can be recon structed based on the wideband measurements at different viewing angles.The sphere spreading of the 1D scattering center projections is exploited.The 1D-2D/3D scatterer map(OTSM)is designed to manifest the high dimensional scattering characteristic of radar targets.The Hough transform and the least squares method are used to extract the stable scattering centers and their scattering coefficients.This modeling method does not need a high density of the spatial grid,which greatly cuts down the necessary original data.The model built in this Way describes the stable point scattering mechanisms in a large spatial extent and can be extrapolated to other frequencies in the optical region.Examples verify the validity of both the model and the method.
摘要：In light of fabricating resonant tunneling diode(RTD),in this paper a GaAs-based resonant tunneling transistor with gate structure(GRTT)has been designed and fabricated successfully.A systematic depiction centers on the designs of material structure,device structure,photo lithography mask,fabrication of device and the measurement and analysis of parameters.The fabricated GRTT has a maximum PVCR of 46 and a maximum transconductance of 8 mS.The work lays the foundation for further improvement on the performance and parameters of RTT.
摘要：A series of Petri net-based definitions were for mulated for describing four types of structural errors in a rule-based system(RBS),including inconsistency,incom pleteness,redundancy and circularity.A marked ω-Petrinet model of acyclic RBS was constructed.Then,its reach ability tree was generated to record all reachable relations between propositions in RBS.Moreover,a backward rea soning forest of a reachable marking was generated for explicitly representing reachable paths in RBS.Finally,a set of theorems and algorithms were provided to analyze and check structural errors.The usability of the research results presented in this paper was illustrated by an example.
摘要：Communication signals should be estimated by a single trial in a brain-computer interface.Since the relativity of visual evoked potentials from different sites should be stronger than those of the spontaneous electro encephalogram(EEG),this paper adopted the time-lock averaged signals from multi-channels as features.200 trials of EEG recordings evoked by target or non-target stimuli were classified by the support vector machine(SVM).Results show that a classification accuracy of higher than 97% can be obtained by merely using the 250-550 ms time section of the averaged signals with channel Cz and Pz as features.It suggests that a possible approach to boost communication speed and simplify the designation of the brain-computer interface(BCI)system is worthy of an attempt in this way.
摘要：The description precision of an excitation signal greatly influences the quality of reconstructed speech in low bit rate vocoders.To improve the reconstruction quality,the DCT_M model is proposed to express the excitation spectral parameter,which transforms the variable length vector to fixed dimension vector through DCT transformation.It then quantizes the fixed length vector using multi-stage vector quantization.Tests show that the proposed method can keep the shape of the entire spectral envelope and reduce model error thus greatly improve the description precision.Test results in the sine excitation linear prediction(SELP)vocoder show that the DCT_M model can improve the naturalness of reconstructed speech,with subjective test score of 65%.
摘要：This paper investigates the enhancement of Langmuir and ion-acoustic wave and the acceleration of the electron in collisionless plasma.in the presence of an external transverse field.Based on hydrodynamic equations,an equation formulizing the parametric instability was derived.Furthermore,the formula for ponderomotive force and the expression that describes the electron acceleration were obtained.The results show that Langmuir and ion-acoustic wave are enhanced and the charged particles can be accelerated by the coupling of wave-wave.In addition,it can be concluded that ponderomotive force,due to the coupling of the external field(pump)to the Langmuir wave(ion-acoustic wave),is the driving force to excite the parametric instability and comprises the high- and low-frequency components.
摘要：Based on a linearized TCP/AOM model,a new proportional integral(PI)controller design approach is proposed.This analytical approach applies H∞ optimization and internal model control(IMC)theory to design active queue management(AQM)routers that support transmission control protocol(TCP)flows.The most important feature of the proposed scheme lies in that it can be explicitly tuned with a single parameter for the trade-off between performance and stability of the AOM control system.It is thus flexible and easy to use in design.The proposed method and the designed PI controller are verified and compared with other existing AOM schemes using ns-2 simulator.The results show the advantages of the new PI controller design approach for AQM routers supporting TCP flows.
摘要：In order to solve the problems of link layer retransmission and packet fragment strategies for IEEE 802.11,this paper proposes a variable packet TCPfriendly rate control(VPTFRC)scheme for streaming media transmission over wireless local area network (WLAN)by researching on the policy of packet size adjustment in transport layer based on the minimum retransmit-delay constraint.Unlike other proposals,this process considers the impact of wireless packet error ratio(PER)on the packet size adjustment and the performance of rate control.Simulation results demonstrate that our proposed process can simultaneously achieve higher throughput,better fairness,shorter transmission delay and less jitter than TFRC.Among them,the ratio of delay,iitter and packet loss rate can reach a maximum improvement ratio of 58%,42%and 85%respectively.
