We study the linearly full holomorphic 2-spheres in a complex Grassmann manifold G(2, 5) by using harmonic sequence and moving frames. We construct some examples of homogeneous holomorphic 2-spheres in G(2, 5) by applying the irreducible unitary representations of SU(2). Then, we determine all linearly full degenerate holomorphic 2-spheres with constant Gaussian curvatures of 2/3 and 4/3, up to U(5) equivalence. Moreover, we prove that all non-degenerate holomorphic 2-spheres with constant Gaussian curvature of 4/3 must be U(5) equivalent under some conditions.
The integral group ring ZG is an important ring structure. This paper focuses on the calculation of the K1 groups of integral group rings. The key point of the problem lies in the calculation of their corresponding SK1 group rings. The SK1 groups of the integral group rings of p groups are relatively easy to calculate,but the SK1 groups of the integral group rings of non-p groups are relatively diffcult to calculate. This article discusses the basic theory of the problem.Furthermore,this article also treats the groups whose orders are p1q1 and discusses the calculation of the SK1 group rings of their integral group rings.
We consider type-Ⅱ censored samples of the exponential distribution. In the case that the hyper-parameters of prior distribution are partly unknown, we construct the parametic empirical Bayes (PEB) estimation for scale parameter with the weighted square-error loss function, study the superiority of PEB estimation over the uniformly minimum variance unbiased estimation (UMVUE) in terms of the mean-square error (MSE) criterion, and obtain its large sample properties. In the case that the hyper-parameters of prior distribution are all unknown, we get the superiority of PEB estimation over UMVUE by comparing the simulated MSE. Finally, we show the superiority of PEB interval estimation by simulation results.
We designed a bracket structure by request of some complex IRST. The aim of the structure optimization was to minimize the mass and moment of inertia. We completed the optimization and analysis in which we took the plane axis thickness as a variable and imposed restrictions on the mode frequency and deadweight distortion. The results show that the bracket mass reduces from 0.62kg to 0.38kg and the moment of inertia reduces from 0.0098kg ·m2 to 0.0056kg ·m2.
Vacuum ultraviolet (VUV) dissociative photoionization of methylbutenol (C5H10O) in 9.0~15.5 eV was investigated with photoionization mass spectrometry using synchrotron radiation (SR). The ionization energy of C5H10O and the appearance energies for the main fragment ions were determined with photoionization efficiency curves. The photodissociation mechanisms of methylbutenol were discussed based on comparison of our experimental results with those predicted by the quantum-chemical calculations. The dissociation channels may be divided into two types: the direct bond cleavage in C5H10O+ and the reactions involving transition states. Transition states and intermediates for C4H+5 and C3H+5 were determined, and the reaction barriers were in agreement with the experimental dissociation energies.
By taking monitoring data of Chagan Lake as an example, fuzzy synthetic assessment was conducted using the principal component weighting, exceeding standard weighting, and analytic hierarchy process. Results show that the principal component weighting can truly reflect the values of various factors; exceeding standard weighting gaves heavier weights to the polluting factors; and the weight values are influenced by subjectivity in analytic hierarchy process.
Water quality parameters were retrieved for the Reservoir Shitoukoumen using Landsat-5 TM data acquired on August 29, 2007 supported by concurrent in-situ measurements. On the basis of cluster analysis (CA) and principle component analysis (PCA) of twenty water samples with seven variables, multiple regression algorithms were established and subsequently used to produce water quality spatial distribution maps over the entire geographic area.
A total of 252 soil samples were collected in Songnen Plain. Reflectance was measured in a controlled laboratory environment. After pre-processing of the primitive spectra, hyper-spectral models for predicting soil organic matter content were built up by using the methods of Stepwise Multiple Linear Regression (SMLR) and Partial Least Squares Regression(PLSR). The results show that the models using the two methods are capable of predicting SOM content and the model using PLSR is more robust.
We construct a synthtic evaluation index system for the regional urbanization.With the method of entropy, synthetic analyses of the urbanization level in the economic belt on the northern slope of the Tianshan Mountains in 2006 are carried out. The main findings are the following. First, the industrialization is the most important factor to promote the urbanization. At the same time,the urbanization mainly incorporates the fast development of the economic urbanization and the social urbanization.However, the population urbanization becomes weak in the overall contribution to the regional urbanization and lags behind the other urbanizations. Finally, using the method of the spatial autocorrelation,we found out that in the spatial distribution of urbanization there is a polarization process of the core cities, Urumqi, Karamay, and Shihezi.
The diffraction wave time-distance curve equation with tilted interface was derived on the basis of geometric seismology theorem, and the existence and uniqueness of the crossover point between the reflection wave and diffraction wave was proved using two methods. Theoretical analyses show that the diffraction wave time-distance curve equation with tilted interface still has the character of hyperbolic curve and that irrespective of facets such as formational dip angle, the location of the minimum travel-time is still above the diffraction point, representing the general form of the horizontal interface condition. The critical parameter computational equation with the coordinates of the crossing point approaching the infinity was studied, and the numerical examples confirmed verified the conclusions. Errors in the conventional seismic interpretation based on practical seismic data were pointed out.
hCLP46 (human CAP10-like protein46), a novel gene, has been screened out from the cDNA library of MDS-AML Patient’s CD34+ stem cell. For to further studying the biological characteristics of this gene tandem affinity purification (TAP) has been used to isolate proteins which specifically interact with hCLP46, and seven specific protein bands were detected. By using liquid chromatography-mass spectrometry and protein database searching, a series of endoplasmic reticulum chaperones were identified. Two major ER chaperone systems, the BiP/Grp94 and the calnexin (CNX)/ calreticulin (CRT) systems, are important in the maturation of hCLP46.
Beamforming is one of the main means for improving the spaceborne synthetic aperture radar(SAR). A broad null beamforming algorithm is proposed to form specified-depth null in the ambiguity regions in order to suppress the echo from those regions.The performance analysis of this scheme is given. Simulation results show efficiency and feasibility of the scheme.
In using anisotropic diffusion equation to reduce SAR image speckles, a number of iterations are needed, which makes it impossible to deal with real-time processing. To solve this problem, an improved algorithm is presented in the paper. Weights of the central pixel and all the direction diffusion coefficients are adaptively adjusted according to image differential coefficients of variation. Diffusion process is accelerated in the homogeneous region, while performance remains in inhomogeneous region. Airborne SAR image was used to verify the effectiveness of the approach. Less iterations are needed in the improved method than in the normal method.
The image enhancement method of Starck et al can not effectively enhance edge-features in SAR image. A new method is proposed based on curvelet for SAR image feature enhancement. Curvelet transform is of multi-scale and multi-direction and has excellent anisotropic characteristic.The proposed method takes full advantages of these properties to extract image edge-features in curvelet domain and locate the curvelet coefficients of edges. The edge-features in image can be enhanced through enhancing the curvelet coefficients of edges. Experiments show that our algorithm enhances features of edges in SAR image more effectively than the method of Starck et al.
A pseudo differential transconductor with configurable common mode feedback block is proposed.It has high linearity and high input dynamic range, and its input and out common-mode voltage can be set at the same level.Due to its good performance, a complex filter can be easily formed by using cascade design method. A frequency control method is also presented based on a simple tuning circuit to auto-adjust the center frequency of the complex filter, which is more suitable on low power applications when compared with the traditional tuning way based on PLL (phase lock loop) architecture. The tuning circuit consists of some basic digital circuits and a simple oscillator. Based on the aforementioned techniques, a three-order Butterworth Gm-C complex filter is designed and fabricated in Chrt35dg 2P4M CMOS process. The measurement results show that it can provide sufficient imagine rejection to satisfy the requirements of IEEE802.15.4 standard.
A satellite-to-ground quantum key communication simulation platform is designed considering the present situation of complex space environment and temporarily unavailable experiment condition domestically. The system is capable of simulating APT and single-photon transmission and capture processes and of correcting wavefront distortion by adaptive-optic. Rational simulation results of tracking and pointing accuracy, AO correction, single-photon acquisition probability,and error rate are obtained by using the system and will be useful in designing actual systems.
Variable length encoded Turbo codes (VL Turbo codes) with constructed joint decoding plane trellis has better decoding performance than the bit-level decoding algorithm. However the plane trellis is complicated, resulting in a high decoding complexity of VL Turbo codes. We construct a space trellis and propose a low-complexity JSCD approach based on VL Turbo codes. Simulation results show that the proposed approach reduces the decoding complexity by 3.8%, compared to the plane trellis, and the gain of Eb/N0 is about 0.2dB at SER=10-4.
Trust-based recommendation is an emerging technique,in which the trust web of users serves as an overlay to locate reliable advisers.Although this technique is claimed to be more robust than collaborative filtering in previous researches,its real strength to resist attacks has not been quantifiably studied.We propose a formal evaluation framework for this topic and compare two representative algorithms in the literature on the data set from Epinions. com.Experiments indicate the key factors for their robustness. Furthermore,several countermeasures are suggested based on these findings.
In 1990 ACM Conference on Computer and Communications Security, Cachin proposed a protocol for private bidding and auctions and gave the security proof. We show that there is a mistake in Cachin’s security proof, and we correct the mistake.
The security of the block cipher ARIA against impossible differential cryptanalysis is studied. First, we analyze the diffusion layer of ARIA and indicate some differential characters of the intermediate state through the encryption transformation. On the basis of these, we show that there is no 6-round impossible differential with the input-and-output differential weight less than ten and that there are only two kinds of 6-round impossible differential with the input-and-output differential weight of ten. Both kinds of the best impossible differentials can be found and can be used to attack the 6-round ARIA with the best results: the data complexity being 2120 chosen plaintexts and the time complexity being 294.5 encryptions of 6-round ARIA.