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Acidic hot water flowthrough pretreatment (AHWF) is an attractive approach primarily because of its high efficiency for sugar recovery. However, a significant portion of carbon content in the solubilized fractions from lignin depolymerization and monosugar degradation has been studied to a lesser degree. Herein, we investigated the solubilized non-carbohydrate products from a series of flowthrough pretreatments of poplar wood by water-only or very dilute acid (0.05% to 0.1% w/w, H2SO4) at different temperatures (220 to 280 °C) and flow rates (10 to 62.5 mL/min). Results revealed that tailoring reaction parameters (temperature) and operational parameters of reactor (flow rate) without adding expensive catalysts can selectively produce specific non-carbohydrate compounds. Up to 50.9% selectivity of vanillin and 45.0% selectivity of syringaldehyde were obtained at 240 °C for water-only treatment with flow rates of 25 mL/min and 62.5 mL/min, respectively. Lower temperature (e.g., 220 °C) was favorable for the formation of coniferyl alcohol, with the highest selectivity of 36.2%. Higher temperature (e.g., 280 °C) or lower flow rate (e.g., 10 mL/min) led to the formation of varied other aromatic compounds and HMF. Adding very dilute acid (0.05% to 0.1% w/w, H2SO4) into the water-only system considerably enhanced the formation of HMF with up to 66.7% selectivity.

This paper describes in detail a novel formulation of the method of characteristics for its application to solve one-dimensional compressible unsteady non-homentropic flow advected along porous wall channels. In particular, the method is implemented into a wall-flow monolith Diesel particulate filter model whose purpose is the pressure drop prediction. The flow inside the monolith channels is considered to be one-dimensional and the flow through the porous wall treated as a source term agree with the Darcy's law. The flow dynamic behaviour at internal nodes of the channels is solved by means of shock capturing methods, whereas the end nodes, or boundary conditions, are solved applying the method of characteristics. The derived solution in this study of the Riemann variables and the entropy level includes the variation along the space-time plane due to cross-section area changes, friction and heat transfer as traditionally stated, but also takes into account the key influence on every line of the flow leaving or entering to the channels through the porous walls. © 2011 Elsevier Inc.

This present paper describes three dimensional computational analysis of complex internal flow in a cross flow fan, (CFF) with a special emphasis on the performance improvement by varying impeller and casing geometries, inlet and tongue clearance gaps. RNG k-? two-equation turbulence model is used to simulate the model with unstructured mesh. Sliding mesh interface is used at the interface between the rotating and stationary domains to capture the unsteady interactions. Three impeller geometries, seven casing configurations and three inlet and tongue clearances are varied in the present study. The efficiency of the fan has improved from 59 % to 71 % and that of casing from 37 % to 61 %. Maximum energy transfer through the impeller takes place in the region where the flow follows the blade curvature. � 2012 Begell House, Inc.

A thin film of a power-law fluid flowing down a porous inclined plane is considered. It is assumed that the flow through the porous medium is governed by the modified Darcy's law together with Beavers-Joseph boundary condition for a general power-law fluid. Under the assumption of small permeability relative to the thickness of the overlying fluid layer, the flow is decoupled from the filtration flow through the porous medium and a slip condition at the bottom is used to incorporate the effects of the permeability of the porous substrate. Applying the long-wave theory, a nonlinear evolution equation for the thickness of the film is obtained. A linear stability analysis of the base flow is performed and the critical condition for the onset of instability is obtained. The results show that the substrate porosity in general destabilizes the film flow system and the shear-thinning rheology enhances this destabilizing effect. A weakly nonlinear stability analysis reveals the existence of supercritical stable and subcritical unstable regions in the wave number versus Reynolds number parameter space. The numerical solution of the nonlinear evolution equation in a periodic domain shows that the fully developed nonlinear solutions are either time-dependent modes that oscillate slightly in the amplitude or time independent stable two-dimensional nonlinear waves with large amplitude referred to as 'permanent waves'. The results show that the shape and the amplitude of the nonlinear waves are strongly influenced by the permeability of the porous medium and the shear-thinning rheology. � 2010 Elsevier B.V.

The Trapped Vortex Combustor (TVC) is a new design concept in which cavities are designed to trap a vortex flow structure established through the use of driver air jets located along the cavity walls. TVC offers many advantages when compared to conventional swirl-stabilised combustors. In the present work, numerical investigation of cold flow (non-reacting) through the two-cavity trapped vortex combustor is performed. The numerical simulation involves passive flow through the two-cavity TVC to obtain an optimum cavity size to trap stable vortices inside the second cavity and to observe the characteristics of the two cavity TVC. From the flow attributes, it is inferred that vortex stability is achieved by circulation and the vortex is trapped inside when a second afterbody is added.The Trapped Vortex Combustor (TVC) is a new design concept in which cavities are designed to trap a vortex flow structure established through the use of driver air jets located along the cavity walls. TVC offers many advantages when compared to conventional swirl-stabilised combustors. In the present work, numerical investigation of cold flow (non-reacting) through the two-cavity trapped vortex combustor is performed. The numerical simulation involves passive flow through the two-cavity TVC to obtain an optimum cavity size to trap stable vortices inside the second cavity and to observe the characteristics of the two cavity TVC. From the flow attributes, it is inferred that vortex stability is achieved by circulation and the vortex is trapped inside when a second afterbody is added.The Trapped Vortex Combustor (TVC) is a new design concept in which cavities are designed to trap a vortex flow structure established through the use of driver air jets located along the cavity walls. TVC offers many advantages when compared to conventional swirl-stabilised combustors. In the present work, numerical investigation of cold flow (non-reacting) through the two-cavity trapped vortex combustor is performed. The numerical simulation involves passive flow through the two-cavity TVC to obtain an optimum cavity size to trap stable vortices inside the second cavity and to observe the characteristics of the two cavity TVC. From the flow attributes, it is inferred that vortex stability is achieved by circulation and the vortex is trapped inside when a second afterbody is added.

When particles in liquid suspensions flow through channels and pipes in a laminar fashion, the resulting parabolic velocity profile gives rise to shear, which induces the particles to rotate. If flowing suspensions containing dielectric particles are immersed in an external electric field, the anisotropic polarization induced in rotating nonspherical particles will vary with the orientation of the particle with respect to the external field; what results is an uncertainty in experimental measurements that involve particle polarization. The present study establishes the limits of this uncertainty and shows that departure from spherical symmetry in individual particles can lead to a significant overlap in measurements attempting to discriminate between particle subpopulations in suspensions. For example, the uncertainty in signal amplitude for a population of activated T-lymphocytes can be as high as 20%. Such concerns arise in applications like field-flow fractionation, dielectrophoretic sorting of particles, flow impedance measurements and cytometry, and, most recently, isodielectric separation, all of which are used to separate particles in a flow based on their dielectric response. This paper considers axisymmetric particles as the first departure from the approximation of spherical symmetry, shows how to calculate an estimate of the size of the population overlap, and suggests possible strategies to minimize it. © 2011 American Physical Society.

Composite primary and secondary aircraft structures have the potential to achieve the same strength and stiffness as conventional metallic structures, but at substantially lower weight. To accomplish this in an efficient and effective manner the joints used to attach these composite structures will be critical. This work investigated the strain distribution in adhesively bonded and hybrid bolted/bonded composite single-strap butt joints using a 2D digital image correlation (DIC) technique and geometrically nonlinear finite element modelling. A high magnification optical setup was used to measure the strains in the through thickness direction, allowing strain measurements in the region of the adhesive and along the bondline in the joint overlap section. This provided a detailed measure of strain flow through the adhesive and into the doubler and adherend under a maximum tensile load of 5338 N (1200 lbf). In all cases a crack developed at the inner overlap section in the hybrid joints and, using DIC techniques, the size of the crack as well as crack tip strains could be determined from the deformed images. The information obtained from the DIC measurements proved valuable in helping to improve the fidelity of the finite element model., 2011 SEM Annual Conference on Experimental and Applied Mechanics, 13 June 2011 through 16 June 2011, Uncasville, CT

Ports are important nodal points that stimulate the US economy. This is particularly true of the Ports of Los Angeles and Long Beach (POLA/LB). Over 40% of all containers shipped to and out of the US flow through this two-port complex. The POLA/LB along with other port complexes face many challenges - including maximizing operational efficiency while simultaneously minimizing risk from catastrophes, including terrorism and other man-made or natural disaster events and minimizing environmental impacts. Often these challenges are at odds with one another - increasing one often comes at the expense of achieving the other. The DHS-funded Center for Risk and Economic Analysis of Terrorism Events (CREATE) is developing a port security risk management and resource allocation system (PortSec). PortSec will support both tactical day-to-day security decision-making and long-term strategic security planning. An initial PortSec prototype (1.0) that supports tactical day-to-day risk assessment and resource allocation is currently undergoing evaluation at POLA/LB. © 2010 IEEE. 264 269 Sponsors: IEEE Boston Section IEEE-USA IEEE Nuclear and Plasma Sciences Society IEEE Engineering in Medicine and Biology Society IEEE Women in Engineering Conference code: 83344 Cited By :5

The time evolution of a thin conducting liquid film flowing down a porous inclined substrate is investigated when an electric field acts normal to the substrate. It is assumed that the flow through the porous medium is governed by Darcy's law together with Beavers-Joseph condition. Under the assumption of small permeability relative to the thickness of the overlying fluid layer, the flow is decoupled from the filtration flow through the porous medium. A slip condition at the bottom is used to incorporate the effects of the permeability of the substrate. From the set of exact averaged equations derived using integral boundary method for the film thickness and for the flow rate, a nonlinear evolution equation for the film thickness is derived through a long-wave approximation. A linear stability analysis of the base flow is performed and the critical Reynolds number is obtained. The results reveal that the substrate porosity in general destabilizes the liquid film flow and the presence of the electric field enhances this destabilizing effect. A weakly nonlinear stability analysis divulges the existence of supercritical stable and subcritical unstable zones in the wave number/Reynolds number parameter space and the results demonstrate how the neutral curves change as the intensity of the electric filed or the permeability of the porous medium is varied. The numerical solution of the nonlinear evolution equation in a periodic domain reveals that the base flow yields to surface structures that are either time independent waves of permanent form that propagate or time-dependent modes that oscillate slightly in the amplitude. Further, it is observed that the shape and amplitude of long-time waveforms are influenced by the permeability of the porous medium as well as by the applied electric field. The results reveal that the destabilization induced by the electric field in an otherwise stable film over a porous medium is exhibited in the form of traveling waves of finite amplitude. The presence of the porous substrate promotes the oscillatory behavior of the long-time waveform; however, the electric field has a tendency to suppress this oscillatory behavior. � 2010 The American Physical Society.