An approximate response of the large system with local cubic nonlinearities subjected to harmonic excitation

This paper considers a multi-degree-of-freedom mechanical system with local cubic nonlinearities. A major concern is placed on nonlinear dynamic behaviors of the system subjected to a soft harmonic excitation under primary resonance condition. The classical model reduction method associated with the single modal resonance theory is employed to investigate the system and obtain a reduced dynamic model with only a single DOF (degree of freedom) under resonance condition. In the case of the soft excitation, the analytical expression of dynamic response and the frequency response characteristic equation can be derived from the reduced model of the system using the harmonic balance method. Some qualitative and quantitative results are then obtained. An example of ten-story nonlinear shear structure is included. Results from the reduction method of the system are in good agreements with those obtained from the numerical integration of the dynamic equation of the original system. This paper demonstrates an effective way in fast analysis of the multi-DOFs nonlinear system qualitatively and quantitatively, especially large scale multi-DOFs system at primary resonance state

Research on Brain and Mind Inspired Intelligence

To address the problems of scientific theory, common technology and engineering application of multimedia and multimodal information computing, this paper is focused on the theoretical model, algorithm framework, and system architecture of brain and mind inspired intelligence (BMI) based on the structure mechanism simulation of the nervous system, the function architecture emulation of the cognitive system and the complex behavior imitation of the natural system. Based on information theory, system theory, cybernetics and bionics, we define related concept and hypothesis of brain and mind inspired computing (BMC) and design a model and framework for frontier BMI theory. Research shows that BMC can effectively improve the performance of semantic processing of multimedia and cross-modal information, such as target detection, classification and recognition. Based on the brain mechanism and mind architecture, a semantic-oriented multimedia neural, cognitive computing model is designed for multimedia semantic computing. Then a hierarchical cross-modal cognitive neural computing framework is proposed for cross-modal information processing. Furthermore, a cross-modal neural, cognitive computing architecture is presented for remote sensing intelligent information extraction platform and unmanned autonomous system

A semi-analytical method for nonlinear vibration of Euler-Bernoulli beams with general boundary conditions

This paper presents a new semianalytical approach for geometrically nonlinear vibration analysis of Euler-Bernoulli beams with different boundary conditions. The method makes use of Linstedt-Poincaré perturbation technique to transform the nonlinear governing equations into a linear differential equation system, whose solutions are then sought through the use of differential quadrature approximation in space domain and an analytical series expansion in time domain. Validation of the present method is conducted in numerical examples through direct comparisons with existing solutions, showing that the proposed semianalytical method has excellent convergence and can give very accurate results at a long time interval

4,8-Dimeth­oxy­furo[2,3-b]quinoline (γ-fagarine)

The title mol­ecule, C13H11NO3, a natural compound extracted from Phellodendron chinense, exhibits a near planar framework: the mean deviations from the furo[2,3-b]quinoline ring system and from the whole mol­ecule (not including the H atoms) are 0.006 and 0.062 Å, respectively

Bacterial community composition in reclaimed and unreclaimed tailings of Dexing copper mine, China

An investigation was conducted to compare the microbial community structures between contaminated and reclaimed mine tailings of Dexing copper mine, Jiangxi province, China. Sample T1 was obtained from tailings site, where reclamation of phytostabilization has been conducted for 20 years successfully whereas, the other one (sample T4) was obtained from the unreclaimed tailings site. Physico-chemical characteristics, chemical speciation of heavy metals Cu, Cd and Zn were revealed to compare the effects of reclamation. A polymerase chain reaction (PCR)-based cloning approach was employed to investigate the bacterial community composition in these two samples. Results indicate the improved physico-chemical conditions and decreased bioavailability of heavy metals Cd and Zn significantly in the sample collected from reclaimed site compared with the other unreclaimed mine tailings site. Phylogenetic analysis indicated that bacteria in these two samples fell into 12 putative phylogenetic divisions. Sample T1 had 12 phyla were present, and the community was predominated by Planctomycetes (20%), α-proteobacteria (16%), Chloroflexi (12%) and Acidobacteria (10%). On the other hand, sample T4 had only 4 phyla and was predominated by y-proteobacteria (86%). The diversity of microbes in sample T1 significantly increased when compared with sample T4. The structure of microbial community composition in the first sample also was optimized to sustain more phyla associated with a healthier soil after reclamation. From the results, it could be deduced that the inventories of bacterial populations such as Planctomycetes, Chloroflexi, α-proteobacteria, Acidobacteria and Actinobacteria predominated in sample T1, but were essentially absent in sample T4. This may serve as potential bioindicator for the reclamation evaluation of tailings.Keywords: Mine tailings, reclamation, bacterial community composition, bioindicatorsAfrican Journal of Biotechnology Vol. 12(30), pp. 4841-484

A Signal Processing Algorithm Based on 2D Matched Filtering for SSAR

This study discusses a smart radar antenna scanning mode that combines features of both the sector-scan mode used for conventional radar and the line-scan mode used for synthetic aperture radar (SAR) and achieves an application of the synthetic aperture technique in the conventional sector-scan (mechanically scanned) radar, and we refer to this mode as sector-scan synthetic aperture radar (SSAR). The mathematical model is presented based on the principle of SSAR, and a signal processing algorithm is proposed based on the idea of two-dimensional (2D) matched filtering. The influences of the line-scan range and speed on the SSAR system are analyzed, and the solution to the problem that the target velocity is very high is given. The performance of the proposed algorithm is evaluated through computer simulations. The simulation results indicate that the proposed signal processing algorithm of SSAR can gather the signal energy of targets, thereby improving the ability to detect dim targets

An approximate response of the large system with local cubic nonlinearities subjected to harmonic excitation

This paper considers a multi-degree-of-freedom mechanical system with local cubic nonlinearities. A major concern is placed on nonlinear dynamic behaviors of the system subjected to a soft harmonic excitation under primary resonance condition. The classical model reduction method associated with the single modal resonance theory is employed to investigate the system and obtain a reduced dynamic model with only a single DOF (degree of freedom) under resonance condition. In the case of the soft excitation, the analytical expression of dynamic response and the frequency response characteristic equation can be derived from the reduced model of the system using the harmonic balance method. Some qualitative and quantitative results are then obtained. An example of ten-story nonlinear shear structure is included. Results from the reduction method of the system are in good agreements with those obtained from the numerical integration of the dynamic equation of the original system. This paper demonstrates an effective way in fast analysis of the multi-DOFs nonlinear system qualitatively and quantitatively, especially large scale multi-DOFs system at primary resonance state