Rapid-manufacturing of micro-structured devices based on MWCNTs/PP composites by using hot embossing replication process

Carbon nanotubes have attracted the fancy of many scientists since their first discovery in 1991. Their small dimensions, strength and remarkable physical properties make them a very unique material with a whole range of promising applications. The most important application of carbon nanotubes based on their important mechanical properties will be as reinforcements in composite materials, especially nanotube-filled polymer composites are an obvious materials application area. In this work, the micro-structured devices in range of micro meter have been manufactured based on polymer/carbon nanotubes composites by using hot embossing replication process. Firstly, the carbon nanotubes with different loading rate (0.1, 1 and 10 %) have been mixed with polypropylene (PP) in molten state to obtain the composite, the rheological properties of MWCNTs/PP composites with different CNT loading ratios were investigated by means of rheometer with a cone-and-plate geometry, the improvement of dispersion of the CNT particles in polypropylene matrix were observed by scanning electronic microscopy. Afterwards, the obtained composite were granulated in particles and used in hot embossing process to realize the replication of micro structured; in this step, a Al mould with micro-motif on surface obtain by machining with computer numerical control machine tools has been used. Finally, the micro-structured motifs on the mould have been successfully transferred with the details on the MWCNTs/PP substrate under the embossing pressure.     

Unsupervised watershed-driven region-based image retrieval

A novel unsupervised strategy for content-based image retrieval is presented. It is based on a meaningful segmentation procedure that can provide proper distributions for matching via the earth mover's distance as a similarity metric. The segmentation procedure is based on a hierarchical watershed-driven algorithm that extracts meaningful regions automatically. In this framework, the proposed robust feature extraction and the many-to-many region matching along with the novel region weighting for enhancing feature discrimination play a major role. Experimental results demonstrate the performance of the proposed strategy.     

Numerical simulation and experimental analysis of the sintered micro-parts using the powder injection molding process

Microsystem Technologies - This paper discusses in detail the development of numerical simulations capable of simulating structural evolution and macroscopic deformation during a powder injection...     

Unsteady three-dimensional numerical study of mass transfer in PEM fuel cell with spiral flow field

Bipolar plate design and its flow field shape have an important effect on the fuel cell performance. In this work, a FORTRAN program has been developed to investigate the effects of the channel width, the number of turns of the spiral channel and the flow direction on the reactants consumption in a proton exchange membrane fuel cell (PEMFC) with a spiral flow field design. The governing equations are discretized using the finite volume method in cylindrical coordinates. The results show that the channel-rib width ratio influences the cell performance; the higher ratio, the more important contact area between the channel and the GDL, the more reactants quantity seeped to the GDL and more uniform reactants distribution is. The increasing the spiral channel turns number improves the reactants distribution uniformity. The channel spiral shape engenders a centrifugal force which enhances the cell performances in the case when the reactants are injected from the external side of the spiral channel and ejected from its internal one.     

Finite-Difference Methods and Validity of a Thermal Model for Landmine Detection With Soil Property Estimation

In this paper, we introduce and validate a 3-D linear thermal model for landmine detection. A finite-difference approximation of generalized solutions to the model is proposed, and its convergence properties are proved. An efficient numerical algorithm based on splitting methods is suggested for solving the discretized problem. Moreover, we introduce methods to estimate the (bare) soil and air-soil interface thermal properties. These parameters depend strongly on weather, environmental conditions, and soil type; their accuracy affects strongly the thermal modeling. The validity of the thermal model with the estimated soil properties is verified by comparing the simulations with data sets acquired in outdoor minefields     

基于三流DBN模型的听视觉情感识别

为更好地对听视觉情感信息之间的关联关系进行建模,提出一种三流混合动态贝叶斯网络情感识别模型(T_AsyDBN)。采用MFCC特征及基于基频和短时能量的局域韵律特征作为听觉输入流,在状态层同步。将面部几何特征和面部动作参数特征作为视觉输入流,与听觉输入流在状态层异步。实验结果表明,该模型优于有状态异步约束的听视觉双流DBN模型,6种情感的平均识别率从 52.14%提高到63.71%。     

基于三音素动态贝叶斯网络模型的大词汇量连续语音识别

考虑连续语音中的协同发音现象,基于词-音素结构的DBN(WP-DBN)模型和词-音素-状态结构的DBN(WPS-DBN)模型,引入上下文相关的三音素单元,提出两个新颖的单流DBN模型:基于词-三音素结构的DBN(WT-DBN)模型和基于词-三音素-状态的DBN(WTS-DBN)模型.WTS-DBN模型是三音素模型,识别基元为三音素,以显式的方式模拟了基于三音素状态捆绑的隐马尔可夫模型(HMM).大词汇量语音识别实验结果表明:在纯净语音环境下,WTS-DBN模型的识别率比HMM,WT-DBN,WP-DBN和WPS-DBN模型的识别率分别提高了20.53%,40.77%,42.72%和7.52%.     

基于基频特征的情感语音识别研究*

探索在不同的情感状态下的基音特征变化规律.通过对含有生气、高兴、悲伤情感语音信号进行分析,总结了情感语音基频的变化规律,确定了用于情感识别的12维的基频的基本特征以及扩展特征,运用混合高斯模型进行情感识别,并作了识别实验,获得了较好的结果.     

EKEMAS,an agent-based geo-simulation framework to support continual planning in the real-word

In this paper, we propose an agent-based geo-simulation framework EKEMAS to assist human planners when planning under strong spatial constraints in a real large-scale space. The approach consists in drawing a parallel between the real environment (for example, a forest in fire) and the simulated environment based on GIS data. This virtual environment uses software agents which are aware of the space and equipped with advanced spatial reasoning capabilities. In addition, we suggest some enhancements for the Continual Planning approach. Our aim is to demonstrate how EKEMAS, when coupled with a continual planning approach and agent’s spatial reasoning capabilities, can assist human planners overcoming obstacles related to real world constraints: dynamic, uncertain, and spatially constrained environment. We illustrate this idea on the forest firefighting problem and we use MAGS as a simulation platform and Prometheus as a fire simulator. Finally, and since plans in the studied case (wildfire fighting) are mainly paths, we also propose a new approach based on agent geo-simulation in order to solve particular Pathfinding problems.