According to the requirements of data bus transfer rate for multi-frequency HF ground wave radar,this paper designed a data transmission system based on Ethernet communication. The system which has employed a digital signal processor TMS320C6748 with a 10 /100 Mb·s- 1adaptive Ethernet interface can both handle a large number of radar sampling data and communicate with the host computer directly without additional hardware platform. This system has the following functions: setting the fixed and variable IP address,receiving and uploading device information,responding to online equipment search commands and uploading radar sampling data regularly. At the same time the system provides a series of effective reliability test plans. Test results show that the network communication system has a good stability and reliability,and the data transfer rate can be up to an average of 80 Mb / s,which meets the needs of the multi-frequency HF ground wave radar system very well.
A key step,recovery and determination of phenol as a by-product,in the synthesis process( N2 sweeping process) of bisphenol A polycarbonate was studied in this work. A simple analysis method of phenol removed from the reactor was developed. Phenol was dissolved in water,and then the concentration of phenol was measured by UV spectrophotometry. Using this analysis method,the rate of recovery phenol and its effect on the viscosity-average relative molecular mass were investigated. The experimental results show that there is a linear relationship between the concentration of phenol and the UV absorbance,and the determination data are exact and reliable by the proposed analysis method. The initial melt temperature of the polycarbonate prepolymer is well above 182 ℃,and the highest initial melt temperature can be up to 224 ℃.When the rate of recovery phenol from the reactor increased,the viscosity-average relative molecular mass of polycarbonate increased. The recovery of phenol from the reactor can be up to 85. 6%.
As Variational Inequalities(VIs)have a close relationship with complementarity problems,and the well-known logarithmic-quadratic proximal(LQP)method has motivated a number of efficient numerical algorithms for solving nonlinear complementarity problems(NCPs),we try to translate a class of constrained variational inequalities into NCP,and apply some LQP-based method is to solve it.
Ti CN hard coatings have been deposited on single crystal silicon and cemented carbide substrates by multi-arc deposition plating techniques using N2 and C2H2as N and C source,respectively,with Ti Target. Coatings morphology,crystal structure,mechanical and tribological properties of Ti CN coatings were studied by X-ray diffraction,atomic force microscopy,scanning electron microscopy,microindentation,and scarification testing. The results showed that both Ti CN and Ti N coatings had Na Cl-type fcc structure. The maximum hardness of the Ti CN coating is 38. 5 GPa,which is much higher than that of Ti N coating( 24. 9 GPa). The adhesion force of the Ti CN coating prepared under optimal condition exceeds 70 N.
In order to investigate the influence of impurities with high positron affinity on the defects depth distribution of positron annihilation measurement,Samples of Mo which implanted with different metal ions were probed by slow positron beam. The results show that defects profiles obtained by positron measurements were deeper than those by SRIM simulation,which demonstrate the defects are easy to spread. The maximum S value depth of Cu+implantation( 150 nm) is greater than that of Mo+implantation( 125 nm),which is caused by the positrons are easier trapped by Cu impurities clusters than Mo vacancy clusters. The Cu clusters positron trapping will effect the measurement of defects depth distribution by slow positron beam.
Basing on the theory of Kharzeev,we use the Wood-Saxon nucleon distribution to replace that of the uniform distribution to improve the magnetic field calculation method of the non-central collision.
Focusing on the explosive increase of on-line images,we propose a data-aware hashing algorithm to achieve efficient image copy detection.It explores the local structure of feature data and combines the reconstruction errors and mapping errors of local structure to construct an optimization objective function.Then we calculate an approximate solution through trace optimization.To further optimize the objective function,we propose a method based on iterated local search(ILS),aiming to further decrease semantic loss during hashing.Experimental results show that our approach successfully finds copy images and achieves high efficiency.
To avoid the co-channel interference caused by the frequency reuse in two-tier femtocells,this paper proposes a resource allocation strategy based on interference coordination. Assuming the Rayleigh fading channel model,the radius of inter-layer interference restricted areas in two-tier femtocells is derived. By assigning the orthogonal subcarriers to users in interference restricted areas,the interference between femtocell-users within the interference restricted areas can be eliminated,and the downlink outage probability of the cell-users can be satisfied. Theoretical analysis and simulation results show that the proposed method can effectively avoid interference between layers,and thus,give a reference to select the appropriate interference limiting radius.
The chiral shift mechanism of lysine molecules under water environment is researched by using 6-31 +G( d,p) basis set,which is based on the method of density functional theory B3 LYP. At the same time,the energies of single points are calculated at the MP2 /6-31 + + G( d,p) level. It is found that there are two reaction channels during the process of chiral shift under water environment. On the first channel,hydrogen directly transfers from chiral carbon to carbonyl oxygen through the medium of water molecules,then the lysine molecule achieves chiral shift after several isomate processes. On the second channel,hydrogen on hydroxyl firstly transfers inside hydroxyl,then hydrogen on the chiral carbon transfers to carbonyl oxygen using the medium of water molecules. Finally through a series of processes,the chiral transition is completed. The calculation of potential energy surfaces during the reactions indicates that the maximum energy barriers of two channels are both from the transition states that hydrogen transfers from chiral carbon to carbonyl oxygen using the medium of water molecules. The energy barriers on the first channel are 208. 1 k J·mol- 1and 177. 0 k J·mol- 1respectively to correspond to the processes using 1H2 O and 2H2 O as mediums. Similarly,the energy barriers on the second channel are 199. 5 k J· mol- 1and 176. 2 k J· mol- 1respectively to correspond to the two situations. Compared with the reactive energies 323. 3k J· mol- 1and 314. 1 k J· mol- 1of monomer situation on two channels,the reactive energies of lysine under water environment are lower. The results show that,water plays an important pole in catalyzing hydrogen transfer reaction during the chiral shift of lysine molecule.
The research achievements about the typical population model,the qualitative study of population model,the classic integral solution of population model,the periodical solution of population model,the periodic solution of population model,the time delay problem of predator-prey population,the reaction diffusion model in multi-populations and the asymptotic solution of singular perturbation population model are recounted respectively.Finally,we simply look into the future for the research area.
As an important strategy of machine learning algorithm design,classifier ensemble has the advantage of higher generalization ability and has been widely used in many difficult real-world applications such as remote sensing,bioinformatics,image processing,and becomes a hot research topic.This paper presents and discusses three wellknown ensemble techniques,i.e.,bagging,boosting and stacking,from different aspects such as:algorithm design idea,pros and cons,improvements and variants,applications to guide researchers to build a more accurate classifier ensemble.Finally,the directions of future studies in this field are summarized.
The leakage current of external circuit is inevitable in electro-dialyzer. The resistance of external circuit is composed by the resistances of the feed / drain pipe and the feed / drain channels,which is the easiest to heat and deformation. In this paper,a circuit model is established in connection with two-compartment electro dialysis device,and the circuit model is simplified according to the law of symmetrical circuit,then a 1 × N order resistor network diagram is obtained. In addition,a formula of current Ikwhich flowed through the resistance r0 of the feed / drain channels is deduced by using Kirchhoff's law. The resistance parameter calculation is measured introduction of the actual electro dialysis. It shows that the feed / drain channels is the easiest to heat and deformation in the outermost of membrane stack; Thermal Effect of the feed / drain channels is more obvious when electro dialysis device is expanded from laboratory scale to industrial scale. The geometric parameters r0/ r1 of the spacer has a great impact on thermal effect of the feed / drain channels.
The source of periodic aliasing and its influence on the accuracy of frequency-domain forward waveform record are analyzed. When sampling interval is fixed,different sampling point N of fast Fourier transform( FFT) greatly affects the accuracy of the forward waveform record. This paper presents a method which increases the sampling point N reasonably to make the amplitude of unit impulse response after point N approaches zero value so that the degree of periodic aliasing is reduced. The performance of frequency-domain waveform forward and inversion is improved by the measure. The experimental results based on Marmousi model show that the method can depress the effect of periodic aliasing availably and increase the accuracy of the waveform forward and inversion. Meanwhile,the oversize number of sampling point brings down the accuracy of the waveform forward and inversion when the length of theoretical data is fixed. The calculation based on the original observation system and original data length of Marmousi model indicates that the optimal sampling point is selected to ensure the performance of waveform inversion.
DYHS hybrid conjugate gradient method is studied in this paper. In order to improve the inversion performance of the gradient-based method and accelerate the convergence,the diagonal elements of approximate Hessian matrix combing with the regularization technique is applied in preprocessing the gradient for adapting the conjugate gradient method. The traditional gradient method and the preconditioned DYHS hybrid conjugate gradient method are all implemented on the varying layered stair-step model. The results show that the improved method not only accelerates the convergence,but also makes the inversion results closer to the theoretic model.
Differential evolution algorithm( DE) is a simple and efficient method when solving complex optimization problems. In this paper,DE was used to solve a class of parameter identification problems of hyperbolic partial differential equation,and according to the characteristics of the problems some improvements for DE were introduced. They included the parametric representation and individual coding method based on the hat function,the performance enhance schemes of the generalized opposition-based learning mechanism and the smoothing operator,and a new fitness value evaluation method which composed of the Tikhonov regularization and total variation regularization. Numerical simulations show that the proposed DE algorithm is very effective for the parameter identification problem of one-dimensional hyperbolic partial differential equation. The algorithm not only obtains the high precision solutions,but also achieves the faster convergence speed.
In this paper,we focus on the effects of steganographic embedding to the correction among steganography pixels on track against the spatial random LSB image steganography.Then,for each stego key in the keyspace,a multi-directional associative mutual information(MAMI)feature has been extracted on the track which controlled by the stego key.And,a mapping correspondence between MAMI feature and stego key is established.According to this approach,the correct key can be identified in the stego keyspace.The experimental results demonstrate that the method which has been introduced can estimate the stego key in random LSB replacement embedding and random LSB matching embedding.The method has better accuracy of detection accuracy compared with existing methods and it can ensure the great effects in various kinds of image sets.
A contourlet transform based multiscale image quality assessment metric is proposed in this paper. At first,both reference images and test images are transformed into YUV( YCr Cb) color space and the luminance component is transformed into contourlet domain to select features from multiscale and multi-direction subbands. The features that could not be distinguished will be combined together by visual perception of just noticeable difference( JND). Then,regional mutual information( RMI) which is calculated by the combined corresponding subbands information is utilized to obtain the similarity of the corresponding subbands. Finally,we use contrast sensitivity function( CSF) to weight the similarity of the corresponding subbands,which is used to calculate the quality assessment score. The experiment results on LIVE( laboratory for image video engineering) database,which contains 5 different types of distortions and 982 distorted images,show that the proposed method can obtain the spearmen rank order correlation coefficient( SROCC) value to be 0. 960 3,the correlation coefficient( CC) value to be0. 969 6 and the root mean square error( RMSE) value to be 5. 658 4. According to the experiment results,the proposed method can efficiently evaluate various distortions. It shows a higher consistency between subjective and objective evaluations and conforms to visual property of human eyes than both peak signal-to-noise ratio( PSNR) and structural similarity( SSIM).
Based on the fact that the amplitude of Doppler spectra significantly enhances when target exists in the radar illumination area,the location of target is found and suppressed by comparing spectra amplitude from different range gates making use of a sliding window in frequency domain. Processing of the measured data shows that the detection results are consistent with the fact,and the suppression algorithm reduces the error in center frequency estimation and improves the accuracy of inversion algorithm. The effectiveness of this algorithm is verified by measured data.
In this study,positron lifetime and Raman scattering spectroscopy are used for studying the micro-structure in Ge Sex( x = 6,7,8,9) chalcogenide glasses samples with differences of Se content. The positron lifetime results indicate that the average positron lifetime has a minimum value at x = 8,which means the minimum free-volume. The Raman scattering results show that the chalcogenide glass samples mainly consist of [Ge Se4]tetrahedral and Seμchain units. These two kinds of results was properly explained by the aggregate grading theory. The proportion of two kinds unit leads to the porosity decrease,corresponding to the decrease of the average positron lifetime. In the sample of this study,Ge Se8 has the smallest free volume,i. e. has the most stable structure.
The efficient query and inference on large-scale RDF data are key problems in the Semantic Web research. In this paper,by studying the RDFS inference rules,we propose a novel index construction scheme of RDF data combined with ORDPATH coding schema——S-Index. The distinguished characteristic of S-Index is that implicit knowledge entailed by RDFS rules can be obtained only by query,which implements the off-line inference. ABox and TBox are distinguished in the RDF data,and we construct the semantic information which describes the Class relationship,Property relationship and the domain and range relationship using the ORDPATH code. The semantic information is encoded and persisted to the RDF SPO index,which loads the SPO index with semantic information and thus creates the semantic index. The SPO index with semantic information will be persisted into database. A series of experiments are designed and conducted to compare the data loading performance and query performance between semantic index and traditional index. The experimental results show that SIndex structure supports efficient query along with effective inference without adding obvious overheads to the traditional index.
