A complex-valued random variable is improper if its complementary covariance is not 0, otherwise it is proper. In this paper, we consider the linear regression models whose errors are independent and identically distributed following an improper complex Gaussian distribution. Such a model may be encountered in signal processing. We use the maximum likelihood method and the two-stage least squares method to estimate the regression coefficients. Differences between these two methods and the complex version of least squares estimates are investigated by simulations. A wind data set is used to illustrate the proposed approach.
We first review Beilinson’s conjecture for a smooth projective curve C over Q. Then we exhibit an element in K2-group of the Fermat curve XN:xN+yN=1 from a toric variety viewpoint. Finally, we focus on the special case of X3 and explicitly express its Hasse-Weil L-function L(X3,s) in terms of the Eisenstein-Kronecker-Lerch series, which allows us to verify that L(X3,s) satisfies a certain functional equation and has a meromorphic continuation in the entire complex plane.
We construct generalized exponential predictors for forecasting gold price using different loss and penalty functions. The construction methods include: 1) ridge regression and 2) selection of linear combinations of EWMA predictors with different parameters by adding LASSO and SCAD penalties based on L1,L2 and the LM loss function which combines both L1 and L2. Practical data show that our models improve the single parameter EWMA model effectively and they perform better than the models suggested in the literature.
In this paper we show the results of numerical simulation and theoretical analysis for two vapor chambers having the same external structure but different internal wick structures. The results show that the vapor chamber with wick bracing pillar has a better thermal performance because wick bracing pillar accelerates fluid circulation and that the numerical simulation can be used for structural optimization and has the guiding significance for improvements in thermal performance of vapor chambers.
In this study, we have found that the presence of 1,4-benzenedithiol (SH) could greatly accelerate Fenton reaction of dyes, such as malachite green and Rhodamine B, but could not improve the mineralization of those dyes. By performing cyclic voltammetry and 1,10-phenanthroline experiments we confirm that the effect of SH as a co-catalyst in the Fenton reaction is based on the accelerated cycle of Fe3+/Fe2+. We compare the effects of 1,4-benzenedithiol and 1,4-hydroquinone.
New bisconjugated compounds, 1, 3-bis (aryl butadienyl ketone) propane derivatives with F, Cl, Br, and 2-naphthyl substituents, were synthesized via double Wittig reactions. Their visible light irradiated photocatalytic intramolecular[4+4]and[2+2]cycloadditions were realized in the presence of Ru(bipy)3Cl2 as catalyst.
Based on core and thin section observation, physical property analysis, and seismic interpretation in Qigequan area in western Qaidam, a new hydrocarbon accumulation mode in the anticline structure is proposed. Hydrocarbon moves mainly along the parallel direction in the wing and the crack in the axes. Hydrocarbon fills first the deep strata and then the shallow formation in the axes.
The bucket foundations by the horizontal load was simulated by means of ABAQUS finite element software, and the results were compared with the model test results. The failure mode of a single tapered bucket foundation by the horizontal load in the saturated soft clay was studied by numerical calculations. On the basis of the numerical calculations with different parameters, we studied the impacts and relative sensitivities of soils’effective unit weight, undrained shear strength, bucket geometry, and loading position on the horizontal bearing capacity of a single tapered bucket foundation in the saturated soft clay.
Dechlorination process and mechanism of p,p'-DDT in soil and dithionite-treated soil by dithionite (200 mmol/L) were investigated under waterlogged culture condition (soil/water=2 g/40 mL). Addition of dithionite resulted in dechlorination of p,p'-DDT by 73% and 79% for 2 d in soil and dithionite-treated soil, respectively, and subsequently the dechlorination slowly continued. The p,p'-DDD and p,p'-DDE were identified to be metabolites of p,p'-DDT in dithionite-treated soil. The dithionite was the predominant contributor of dechlorination of p,p'-DDT, and Fe2+ in dithionite-treated soil also had contribution. Dithionite could be used to develop a remediation option for DDTs-contaminated soils.
Distributions of As, Hg, Cd, Cr, and Pb in soil and vegetable under different rotation modes were studied in an one-year experiment at the demonstration bases of vegetable in Damintun town, Shenyang city. The results showed that As, Hg, Cr, and Pb contents in soil and vegetable were lower than the criteria in the national safety standard. Spinach-tomato-kidney bean rotation mode could reduce the Cd-concentration in soil and decrease the integrative pollution index. However spinach is improper in that region because of enrichment of Cd. So a rotation mode of lettuce (or rape)-tomato-kidney is suggested, instead of the mode of spinach-tomato-kidney.
Wavelet transform and SPIHT has achieved a perfect effect on SAR(synthetic aperture radar) image compression, but the complexity of SPIHT limits the encoding rate. Considesing slow coding rate and large memory consuming of SPIHT, we propose a modified listless SPIHT in order to speed up the coding rate. The experiments show that this new method can achieve the same compression effect as SPIHT while has a far faster rate than the original one. So it is suitable for real-time application.
We have studied the low precision of parameter estimation for the moving target in airborne single antenna SAR/GMTI mode. Firstly, the Doppler shift parameter and range walk parameter are used to estimate the radical velocity of the moving target, and the range walk parameter is corrected with the estimation results. Secondly, the improved reflectivity displacement method algorithm is used to estimate the Doppler frequency rate, and the azimuth velocity can be calculated when there is no acceleration. Thus, parameter estimation and focusing imaging can be completed at the same time. Simulation results show the effectiveness of the proposed method.
A feedback algorithm based on digital correlation method is investigated, and it works at relatively low sampling frequency to solve multi-channel MUXDAC synchronizing problem. The principle and implementation method of the algorithm are analyzed. The influences of the parameters on accuracy are also analyzed. The algorithm has been used in a multi-channel radar AWG system, and it has been vesified that the algorithm can be implemented easily and improves the reliability of the whole system.
The acquisition of spread spectrum signal is an important part of the DSSS(direct sequence spread spectrum) receiving system.For solving the existing problems such as heavy calculation and low speed, the acquisition method based on the GPU acceleration is proposed. The acquisition method based on the cyclic correlation is converted into the process of CUDA thread blocks, and then the process of acquisition is executed completely through GPU. The simulation results show that the method based on GPU improves the executive efficiency of DSSS systems.
We propose a new method (LC-DBN) of gene regulatory network (GRN) construction based on the theory of dynamic Bayesian network. In the process of GRN construction, we learn optimal regulation time unit lag for each gene and combine gene expression data with transcription factor binding location data. The construction experiments on GRN of 25 Saccharomyces Cerevisiae cell cycle data was carried out, and the results indicate that the new method enhances sensitivity by 0.72% and accuracy by 0.16% compared to Tan’s method.
Considering the problems(complicated computation and huge data) of SEBVHOS(surface extraction from binary volumes with high-order smoothness), we propose a parallel algorithm to accelerate the SEBVHOS execution. Firstly, SEBVHOS is parallelized. Secondly, optimization techniques are applied to improve performance of the algorithm. Meanwhile, matrix compression is applied to improve performance of memory space. Experiments show that the average speed-up ratio achieves 1.87 in a dual-core system.
We present an evaluation algorithm based on task division and scheduling at run-time on heterogeneous multi-core systems. The algorithm can achieve speedups of specific tasks running on different configurations for multi-core platform within the reconfigurable hardware architectures. We build a simulation environment and implement a prototype on FPGA. Experimental results show that the algorithm can achieve 90% of theoretical speedup with dependency of different tasks and 98.9% without data dependency.
In view of spatial steganography, we discuss the complementarity among three sets of the features including statistical moments of wavelet characteristic functions, high-order statistics, and subtractive pixel adjacency matrix, and we use the mutual information criterion and boosting feature selection to fuse the features. Analytic and experimental results show that the complementarity does exist among the features and the fusion enhances accuracy of steganalysis.
In this paper, we present differential fault analysis on HIGHT with a single byte fault model. We inject the fault at the third and fourth rounds from bottom.The 128-bit user key can be obtained by using 32 faulty ciphertexts with a computational complexity of 256. The pre-computed complexity is 232.
We propose a quantum identification scheme. The scheme uses one-time random strings to hide the key shared by both sides, and the verification algorithm is independent of the random strings. So it protects the key. The scheme is secure even if the adversary has unlimited resource of computation.
A C-band wide-band 2-dimensional scanning solid-state active phased array antenna for airborne synthetic aperture radar (SAR) is designed. Microstrip patch is used and excited by a wide-band dipole. Metal walls and metal grounding screws are used to reduce the mutual couplings between microstrip antenna elements. The measure results indicate that the bandwidth of the antenna exceeds 800 MHz (VSWR<1.6).