Polysaccharides Based Random and Unidirectional Aerogels for Thermal and Mechanical Stability

Owing to the increasing energy demands and the environmental constraints, the need for bio-based materials has been on the rise due to their variety of favorabl...     

一种彩色图像的二维纹理识别方法

基于仿射矩正则化技术，推导出了新的光照仿射不变特征：Zernike矩、多波段相关函数，通过正则化方法实现仿射不变矩，采用组合矩方法和奇异值分解方法实现光照不变性，在推导光照不变性时必须使用复数值矩(如Zernike矩)，因为实数值仿射不变矩不能实现独立于光照变化的仿射不变性。实验结果表明，所提出的纹理识别方法具有很好的识别效果。     

Model and characteristic of a new underactuated manipulator and its simulation

The virtual prototype of the type of under-actuated manipulator was established under the Solidworks. It is proved that the manipulator has the nonholonomic characteristic from the theoretical analysis to this model. The digital model was imported into ADAMS and the kinematics simulation and analysis were accomplished. The research conclusion shows that underactuated manipulator is controllable from the simulation analysis perspectives. It also provides theoretical foundation for prototype’s debugging and c...     

Forecasting the Dubai financial market with a combination of momentum effect with a deep belief network

Applying recent advances in machine learning techniques, we propose a hybrid model to forecast the Dubai financial market general index. Particularly, we exploit a deep belief networks model that applies a restricted Boltzmann machine as its main component in combination with momentum effects. We also introduce an innovative way of selecting the inputs by using momentum effects. With this hybrid methodology we generate a prediction model along with a comparison of three different linear models. The results obtained from the hybrid model are better and more stable than the three linear models. The findings support that the hybrid model we applied will find their way into finance because of their reliability and good performance.     

Some New Results on Orthogonally Constrained Candecomp

The use of Candecomp to fit scalar products in the context of Indscal is based on the assumption that, due to the symmetry of the data matrices involved, two components matrices will become equal when Candecomp converges. Bennani Dosse and Ten Berge (2008) have shown that, in the single component case, the assumption can only be violated at saddle points in the case of Gramian matrices. This paper again considers Candecomp applied to symmetric matrices, but with an orthonormality constraint on the components. This constrained version of Candecomp, when applied to symmetric matrices, has long been known under the acronym Indort. When the data matrices are positive definite, or have become positive semidefinite due to double centering, and the saliences are nonnegative – by chance or by constraint –, the component matrices resulting from Indort are shown to be equal. Because Indort is also free from so-called degeneracy problems, it is a highly attractive alternative to Candecomp in the present context. We also consider a well-known successive approach to the orthogonally constrained Indscal problem and we compare, from simulated and real data sets, its results with those given by the simultaneous (Indort) approach.     

Comparative analysis of the genome sequences of Bordetella pertussis,Bordetella parapertussis and Bordetella bronchiseptica

Bordetella pertussis, Bordetella parapertussis and Bordetella bronchiseptica are closely related Gram-negative beta-proteobacteria that colonize the respiratory tracts of mammals. B. pertussis is a strict human pathogen of recent evolutionary origin and is the primary etiologic agent of whooping cough. B. parapertussis can also cause whooping cough, and B. bronchiseptica causes chronic respiratory infections in a wide range of animals. We sequenced the genomes of B. bronchiseptica RB50 (5,338,400 bp; 5,007 predicted genes), B. parapertussis 12822 (4,773,551 bp; 4,404 genes) and B. pertussis Tohama I (4,086,186 bp; 3,816 genes). Our analysis indicates that B. parapertussis and B. pertussis are independent derivatives of B. bronchiseptica-like ancestors. During the evolution of these two host-restricted species there was large-scale gene loss and inactivation; host adaptation seems to be a consequence of loss, not gain, of function, and differences in virulence may be related to loss of regulatory or control functions.     

衰落性AWGN信道的OFDM性能保护间隔的优化

阐述了OFDM系统的基本原理及保护间隔(GI)对系统的影响.首先就保护间隔(GI)参数在接收机干扰问题上起到的作用进行了讨论.然后计算了保护间隔参数的最佳值,结果表明它们对最大延迟有很强的依赖性.同时对多径衰落和加性高斯白噪声同时存在的QPSK调制情况进行了仿真,从而分别得出了GI、信噪比(SNR)、最大传播延迟和副载波数量与误码率的关系.     

机械合金化法制备的Cu/SiC纳米复合材料的组织、热性能和力学性能评估

Nano-sized silicon carbide (SiC: 0wt%, 1wt%, 2wt%, 4wt%, and 8wt%) reinforced copper (Cu) matrix nanocomposites were manufactured, pressed, and sintered at 775 and 875°C in an argon atmosphere. X-ray diffraction (XRD) and scanning electron microscopy were performed to characterize the microstructural evolution. The density, thermal expansion, mechanical, and electrical properties were studied. XRD analyses showed that with increasing SiC content, the microstrain and dislocation density increased, while the crystal size decreased. The coefficient of thermal expansion (CTE) of the nanocomposites was less than that of the Cu matrix. The improvement in the CTE with increasing sintering temperature may be because of densification of the microstructure. Moreover, the mechanical properties of these nanocomposites showed noticeable enhancements with the addition of SiC and sintering temperatures, where the microhardness and apparent strengthening efficiency of nanocomposites containing 8wt% SiC and sintered at 875°C were 958.7 MPa and 1.07 vol%?1, respectively. The electrical conductivity of the sample slightly decreased with additional SiC and increased with sintering temperature. The prepared Cu/SiC nanocomposites possessed good electrical conductivity, high thermal stability, and excellent mechanical properties.     

Model and characteristic of a new underactuated manipulator and its simulation

The virtual prototype of the type of underactuated manipulator was established under the Solidworks. It is proved that the manipulator has the nonholonomic characteristic from the theoretical analysis to this model. The digital model was imported into ADAMS and the kinematics simulation and analysis were accomplished. The research conclusion shows that underactuated manipulator is controllable from the simulation analysis perspectives. It also provides theoretical foundation for prototypes debugging and control.