排序方式: 共有31条查询结果,搜索用时 15 毫秒
11.
12.
13.
Kianoush Molla-Abbasi 《Engineering Fracture Mechanics》2008,75(6):1545-1568
Analytical expressions for the elastic constant stress terms of the asymptotic field, the so called T-stresses, for internal mixed-mode elliptical cracks in infinite homogeneous and isotropic elastic solids are addressed. To solve the problem the mixed-mode crack problem is divided into sub-problems using the superposition method, and each sub-problem is then solved for the asymptotic stress field. Considering the expansion of the local stress field at the crack front, the elastic T-stress terms are derived for each sub-problem. The results are superimposed to give the analytical expressions of the so far missing elastic T-stresses for mixed-mode elliptical cracks.The effect of the T-stresses on the size and shape of the plastic zone at the crack tip is discussed, and analytical results are compared to the ones from finite element analyses, both for the T-stress components and the size of the plastic zone. For an accurate prediction of the plastic zone all singular and constant terms (T-stresses) in the stress expansion formulae should be considered. It is observed that negative T-stresses increase the size of the plastic zone, while positive ones reduce it. 相似文献
14.
Analytical expressions for all non-singular stress terms of the asymptotic crack tip field, the so-called T-stresses of internal mixed mode circular (penny shaped) cracks in infinite homogeneous and isotropic elastic solids are addressed. To solve the problem the mixed mode crack problem is divided into sub-problems using the superposition method, and each sub-problem is then solved for the asymptotic stress field. Considering the expansion of the local stress field at the crack front, the elastic T-stress terms are derived for each sub-problem. The results are superimposed to give the analytical expressions of the so far missing elastic T-stresses of internal mixed mode penny shaped cracks.The effect of the T-stresses on the size and shape of the plastic zone at the crack tip is discussed, and analytical results are compared to the ones from finite element analyses, both for the T-stress components and the size of the plastic zone. For an accurate prediction of the plastic zone all the singular terms and the constant terms (T-stresses) in the stress expansion formulae should be considered. It is observed that negative T-stresses increase the size of the plastic zone, while positive ones reduce it. 相似文献
15.
M. Reza Mozafari Kianoush Khosravi-Darani G. Gokce Borazan Jian Cui Abbas Pardakhty Seyhun Yurdugul 《International Journal of Food Properties》2013,16(4):833-844
Nanoliposomes are microscopic vesicles composed of phospholipid bilayers entrapping one or more aqueous compartments. Their unique properties have triggered numerous applications in several scientific and technological fields. Nanoliposomes can provide controlled release of various bioactive agents, including food ingredients and nutraceuticals, at the right place and the right time. Therefore, they increase the effectiveness and cellular uptake of the encapsulated material. Reactive, sensitive, or volatile additives (vitamins, enzymes, antioxidants, slimming agents, etc.) can be turned into stable ingredients using nanoliposomes. This article reviews various aspects of nanoliposomes including currently available preparation methods, and their application in food technology. 相似文献
16.
17.
18.
Nazarpour K Ethier C Paninski L Rebesco JM Miall RC Miller LE 《IEEE transactions on bio-medical engineering》2012,59(7):1829-1838
A constrained point-process filtering mechanism for prediction of electromyogram (EMG) signals from multichannel neural spike recordings is proposed here. Filters from the Kalman family are inherently suboptimal in dealing with non-Gaussian observations, or a state evolution that deviates from the Gaussianity assumption. To address these limitations, we modeled the non-Gaussian neural spike train observations by using a generalized linear model that encapsulates covariates of neural activity, including the neurons' own spiking history, concurrent ensemble activity, and extrinsic covariates (EMG signals). In order to predict the envelopes of EMGs, we reformulated the Kalman filter in an optimization framework and utilized a nonnegativity constraint. This structure characterizes the nonlinear correspondence between neural activity and EMG signals reasonably. The EMGs were recorded from 12 forearm and hand muscles of a behaving monkey during a grip-force task. In the case of limited training data, the constrained point-process filter improved the prediction accuracy when compared to a conventional Wiener cascade filter (a linear causal filter followed by a static nonlinearity) for different bin sizes and delays between input spikes and EMG output. For longer training datasets, results of the proposed filter and that of the Wiener cascade filter were comparable. 相似文献
19.
Reza Mohammadi Maryam Mahmoudzade Mohsen Atefi Kianoush Khosravi‐Darani M R Mozafari 《International Journal of Dairy Technology》2015,68(1):11-23
Among microencapsulation techniques used in food production, nanoliposomes are known to be one of the most interesting methods for the encapsulation of flavours, essential oils, amino acids, vitamins, minerals, enzymes, micro‐organisms, redox agents, colourants, antioxidants and antimicrobials. Research has also been conducted on possible applications of nanoliposomes in cheese production by the encapsulation of ferrous glycinate, ferrous sulphate, antioxidants, nisin, β‐galactosidase and cheese‐ripening enzymes. In this article, nanoliposome application in cheese production has been reviewed under three main themes, namely (i) acceleration of cheese ripening, (ii) fortification of cheese with vitamins and minerals and (iii) increasing shelf life of cheese products. Various aspects of nanoliposome application in cheese technology including currently available preparation methods, efficiency of nanoliposomal enzymes, their effects on the acceleration of cheese ripening as well as rheological and chemical properties of the cheese curd are discussed. 相似文献
20.