Current Issue : July - September Volume : 2015 Issue Number : 3 Articles : 4 Articles
Dust flames are associated with two-phase combustion phenomena where flame characteristics depend\non interactions between solid and gas phases. Since organic dust particles can be effectively utilized in energy\nproduction systems, investigation of this phenomenon is essential. In this study, an analytical model is presented\nto simulate the combustion process of moist organic dust. The flame structure is divided into three zones: preheat\nzone, reaction zone, and postflame zone. To determine the effects of moisture content and volatile evaporation, the\npreheat zone is also divided into four subzones: first heating subzone and drying subzone, second heating subzone,\nand volatile evaporation subzone. The results obtained from the presented model are in reasonable agreement with\nexperimental data for lycopodium particles. An increase in moisture content causes a reduction in burning velocity\nowing to moisture evaporation resistance. Consequently, the effects of some important parameters, like volatilization\ntemperature, volatilization Damk�¶hler number and drying Damk�¶hler number are investigated. In special cases,\nlike high moisture content, low volatilization temperature, and high drying resistance, the second heating subzone\nis omitted....
Two-dimensional free surface flows generated by a moving disturbance are considered. The flows are\nassumed to be potential. The effects of electric field, gravity and surface tension are included in the dynamic\nboundary condition. The disturbance is chosen to be a distribution of pressure moving at a constant velocity. Both\nlinear and nonlinear results are presented. For some values of the parameters, the linear theory predicts unbounded\ndisplacements of the free surface. It is shown that this nonuniformity is removed by developing a weakly nonlinear\ntheory. There are then solutions which are perturbations of a uniform stream and others which are perturbations of\nsolitary waves with decaying tails....
Although various forms for the Hashinââ?¬â??Shtrikman bounds on the effective elastic properties of inhomogeneous\nmaterials have been written down over the last fewdecades, it is often unclear howto construct and compute\nsuch bounds when the material is not of simple type (e.g. isotropic spheres inside an isotropic host phase). Here,\nwe show how to construct, in a straightforward manner, the Hashinââ?¬â??Shtrikman bounds for generally transversely\nisotropic two-phase particulate composites where the inclusion phase is spheroidal, and its distribution is governed\nby spheroidal statistics. Note that this case covers a multitude of composites used in applications by taking various\nlimits of the spheroid, including both layered media and long unidirectional composites. Of specific interest in this\ncase is the fact that the corresponding Eshelby and Hill tensors can be derived analytically. That the shape of the\ninclusions and their distribution can be specified independently is of great utility in composite design. We exhibit\nthe implementation of the computations with several examples....
central problem in biomechanical studies of personalized human left ventricular (LV) modelling is to\nestimate material properties from in vivo clinical measurements. In this work we evaluate the passive myocardial\nmechanical properties inversely from the in vivo LV chamber pressureââ?¬â??volume and strain data. The LV myocardium\nis described using a structure-based orthotropic Holzapfelââ?¬â??Ogden constitutive law with eight parameters. In the\nfirst part of the paper we demonstrate how to use a multi-step non-linear least-squares optimization procedure to\ninversely estimate the parameters from the pressureââ?¬â??volume and strain data obtained from a synthetic LV model\nin diastole. In the second part, we show that to apply this procedure to clinical situations with limited in vivo\ndata, additional constraints are required in the optimization procedure. Our study, based on three different healthy\nvolunteers, demonstrates that the parameters of the Holzapfelââ?¬â??Ogden law could be extracted from pressureââ?¬â??volume\nand strain data with a suitable multi-step optimization procedure. Although the uniqueness of the solution cannot\nbe addressed using our approaches, the material response is shown to be robustly determined....
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