Design guidelines for wieldier discretionary review: evidence from Portland

ABSTRACT

The use of design guidelines in development control continues to be popular, especially when regulators seek to limit the scope of discretionary latitude. However, the question of how a guidelines framework can be designed to suit the time-constrained and deliberative nature of review hearings remains unaddressed. Using evidence from Portland, this study concludes that boards and staff work around these difficulties by using guidelines in combination, and in so doing almost always undermine their intent. The paper suggests how predefined roadmaps to articulate and combine guideline use can make the process wieldier.     

Migrating multi-block lattice Boltzmann model for immiscible mixtures: 3D algorithm development and validation

The lattice Boltzmann method (LBM) has emerged as a powerful numerical fluid solver especially in the areas of multi-component and multi-phase mixtures. However the LBM uses the particle velocity for the determination of the model time step required by the Courant-Friedrichs-Lewy (CFL) stability condition. This degrades the LBM efficiency, when compared with standard CFD solvers which use instead the macroscopic velocity for the CFL requirements. This paper discusses the development and validation of a 3D migrating multi-block model aiming at the acceleration of the LBM solution. The proposed algorithm is especially applicable to the Gunstensen multi-component model, in which a fine grid block engulfs the fluid-fluid interface and migrates with it. This increases the efficiency of the LBM since less iteration steps are required in areas of marginal interest, and it enables a better interface resolution because the fluid interface is always covered with finer grid. The method was demonstrated by simulating the case of a 3D rising bubble in infinite medium, in which the model results for the bubble terminal velocity were in good agreement with a semi-analytical solution, and the produced shapes fitted very well an experimental shape regime map.     

Stabilization of projection‐based reduced‐order models

A rigorous method for stabilizing projection‐based linear reduced‐order models without significantly affecting their accuracy is proposed. Unlike alternative approaches, this method is computationally efficient. It requires primarily the solution of a small‐scale convex optimization problem. Furthermore, it is nonintrusive in the sense that it operates directly on readily available reduced‐order operators. These can be precomputed using any data compression technique including balanced truncation, balanced proper orthogonal decomposition, proper orthogonal decomposition, or moment matching. The proposed method is illustrated with three applications: the stabilization of the reduction of the Computational Fluid Dynamics‐based model of a linearized unsteady supersonic flow, the reduction of a Computational Structural Dynamics system, and the stabilization of the reduction of a coupled Computational Fluid Dynamics–Computational Structural Dynamics model of a linearized aeroelastic system in the transonic flow regime. Copyright © 2012 John Wiley & Sons, Ltd.     

Structural Studies on Residual Fuel Oil Asphaltenes by RICO Method

Structural characterization of asphaltenes isolated from Saudi Arabian heavy and medium crude oils was undertaken by using ruthenium ion catalyzed oxidation (RICO) method. The RICO method was capable to convert aromatic carbons selectively into carbon dioxide and carboxylic acids and esters group while leaving aliphatic and naphthenic structures of asphaltenes essentially unaffected. Detailed analyses of RICO products of both Arab heavy and Arab medium asphaltenes were conducted using FT-IR, ¹³C-NMR, IC, GPC, and GC-MS techniques. These analyses indicate that the aqueous phase fraction (water-soluble products) obtained from RICO reaction of asphaltenes consists of aliphatic dicarboxylic acids and aromatic poly carboxylic acids with longer alkyl chains. The ¹³C-NMR and GC-MS analyses of organic phase products of asphaltenes indicate that this fraction contains large amount of aliphatic carboxylic acids with longer alkyl groups. The oxidation products of both Arab heavy and Arab medium asphaltenes were found to be dominated by a homologous series of straight chain monocarboxylic acids suggesting that the normal alkyl chains are major and important constituents of the chemical structure of both asphaltenes.     

Green Propulsion: Catalysts for the European FP7 Project GRASP

The Green Advanced Space Propulsion (GRASP) project investigated the issue of green propulsion and the possibility of replacing presently used toxic hydrazine propellant by green propellants. This project was financed by the European Commission in the 7th Framework Program (FP7). A large data base of about 100 green propellants was compiled including physical and material properties, toxicity and performance data. A preliminary selection was conducted to identify the most promising green propellant candidates for experimental work. Catalytic ignition, a very simple and robust subsystem with restart possibility, was thoroughly investigated focusing on the catalyst–propellant couple. For the whole project, more than 50 catalyst variations have been prepared comprising ceramic pellets, ceramic monoliths, metallic foams or gauzes. Very promising green propellant candidates, e.g. ammonium dinitramide-based monopropellants, have been methodically investigated leading to the development and manufacturing of advanced pellet-based catalysts for ionic liquid decomposition. The decomposition of concentrated hydrogen peroxide (87.5 wt%) for bipropellant applications led to a thorough investigation of monolithic catalysts. Examination of monolith parameters (channel shape, channel density, material) and preparation parameters (washcoating procedure, active phase precursor) led to the development of very efficient catalysts showing high activity and stability: 17.9 kg of H₂O₂ could be decomposed for the first time by a single monolithic catalyst.     

Magnetic nanowire synthesis: A chemical engineering approach

Bimetallic one‐dimensional cobalt–nickel magnetic nanowires capped on both sides with conical heads were synthesized using the polyol process. Then, the process was scaled up to produce magnetic nanowires in sample aliquots of approximately 20 g. The scale‐up strategy involved improving the mixing reagents using either axial or radial mixing configurations and was experimentally validated by comparing the structural and magnetic properties of the resulting nanowires. The results indicated a connection between the flow patterns and the size and shape of the nanowires. When a Rushton turbine was used, shorter nanowires with unconventional small heads were obtained. Because the demagnetizing field is strongly localized near or inside these heads, the coercive field was enhanced nearly twofold. These results were confirmed by micromagnetic simulations using isolated nanowires. In addition, the development of flow patterns at the small and pilot scales was predicted and compared using three‐dimensional turbulent computational fluid dynamics simulations. © 2014 American Institute of Chemical Engineers AIChE J, 61: 304–316, 2015