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Robust Technique (robust + technique)

Distribution by Scientific Domains
Engineering28%

Selected Abstracts

Janus Supraparticles by Induced Phase Separation of Nanoparticles in Droplets

ADVANCED MATERIALS, Issue 19 2009
Rhutesh K. Shah
Biphasic Janus particles with a precisely tunable internal morphology are fabricated using a novel, versatile, and robust technique. This technique can be used in conjunction with microfluidics to produce monodisperse particles, or can be combined with bulk emulsification techniques to produce large quantities of particles. [source]

Discrete element method for modelling solid and particulate materials

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2007
Federico A. Tavarez
Abstract The discrete element method (DEM) is developed in this study as a general and robust technique for unified two-dimensional modelling of the mechanical behaviour of solid and particulate materials, including the transition from solid phase to particulate phase. Inter-element parameters (contact stiffnesses and failure criteria) are theoretically established as functions of element size and commonly accepted material parameters including Young's modulus, Poisson's ratio, ultimate tensile strength, and fracture toughness. A main feature of such an approach is that it promises to provide convergence with refinement of a DEM discretization. Regarding contact failure, an energy criterion based on the material's ultimate tensile strength and fracture toughness is developed to limit the maximum contact forces and inter-element relative displacement. This paper also addresses the issue of numerical stability in DEM computations and provides a theoretical method for the determination of a stable time-step. The method developed herein is validated by modelling several test problems having analytic solutions and results show that indeed convergence is obtained. Moreover, a very good agreement with the theoretical results is obtained in both elastic behaviour and fracture. An example application of the method to high-speed penetration of a concrete beam is also given. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Localized "Click" Chemistry Through Dip-Pen Nanolithography,

ADVANCED MATERIALS, Issue 24 2007
A. Long
Local reactions are triggered by delivering molecules from an AFM probe tip, allowing for direct modification of chemically functionalized surfaces. Silicon wafer-bound acetylene moieties readily undergo 1,3-dipolar cycloadddition with solution-phase azides delivered from an AFM tip. This selective and robust technique allows for the facile creation and placement of sub-micrometer-sized features. [source]

An examination of exergy destruction in organic Rankine cycles

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 10 2008
P. J. Mago
Abstract The exergy topological method is used to present a quantitative estimation of the exergy destroyed in an organic Rankine cycle (ORC) operating on R113. A detailed roadmap of exergy flow is presented using an exergy wheel, and this visual representation clearly depicts the exergy accounting associated with each thermodynamic process. The analysis indicates that the evaporator accounts for maximum exergy destroyed in the ORC and the process responsible for this is the heat transfer across a finite temperature difference. In addition, the results confirm the thermodynamic superiority of the regenerative ORC over the basic ORC since regenerative heating helps offset a significant amount of exergy destroyed in the evaporator, thereby resulting in a thermodynamically more efficient process. Parameters such as thermodynamic influence coefficient and degree of thermodynamic perfection are identified as useful design metrics to assist exergy-based design of devices. This paper also examines the impact of operating parameters such as evaporator pressure and inlet temperature of the hot gases entering the evaporator on ORC performance. It is shown that exergy destruction decreases with increasing evaporator pressure and decreasing turbine inlet temperatures. Finally, the analysis reveals the potential of the exergy topological methodology as a robust technique to identify the magnitude of irreversibilities associated with real thermodynamic processes in practical thermal systems. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Bayesian optimal reconstruction of the primordial power spectrum

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2009
M. Bridges
ABSTRACT The form of the primordial power spectrum has the potential to differentiate strongly between competing models of perturbation generation in the early universe and so is of considerable importance. The recent release of five years of Wilkinson Microwave Anisotropy Probe observations have confirmed the general picture of the primordial power spectrum as deviating slightly from scale invariance with a spectral tilt parameter of ns, 0.96. None the less, many attempts have been made to isolate further features such as breaks and cut-offs using a variety of methods, some employing more than ,10 varying parameters. In this paper, we apply the robust technique of the Bayesian model selection to reconstruct the optimal degree of structure in the spectrum. We model the spectrum simply and generically as piecewise linear in ln k between ,nodes' in k space whose amplitudes are allowed to vary. The number of nodes and their k -space positions are chosen by the Bayesian evidence so that we can identify both the complexity and location of any detected features. Our optimal reconstruction contains, perhaps, surprisingly few features, the data preferring just three nodes. This reconstruction allows for a degree of scale dependence of the tilt with the ,turn-over' scale occurring around k, 0.016 Mpc,1. More structure is penalized by the evidence as overfitting the data, so there is currently little point in attempting reconstructions that are more complex. [source]

Amplified fragment length polymorphism analysis in diploid cultivars of rhodesgrass

PLANT BREEDING, Issue 1 2001
B. E. Ubi
Abstract The amplified fragment length polymorphism (AFLP) technique was applied to detect genetic variation in a sample of 47 plants representing 12 diploid cultivars of rhodesgrass. In this analysis, 50±91 easily scorable fragments could be detected in a single reaction. Each of the individual plants was uniquely identified by a combination of three primer pairs and an 80.2% level of polymorphism was obtained. Large amounts of genetic variation were present within all the cultivars. The results showed that AFLPs could be a robust technique for genome analysis in rhodesgrass with a promising potential as a breeding tool. [source]

Spiral Multislice Computed Tomography Coronary Angiography: A Current Status Report

CLINICAL CARDIOLOGY, Issue 9 2007
P. J. De Feyter M.D., PH.D.
Abstract Multislice computed tomography coronary angiography (MSCT-CA) has emerged as a powerful noninvasive diagnostic modality to visualize the coronary arteries and to detect significant coronary stenoses. The latest generation 64-slice computed tomography (CT) scanners is a robust technique which allows high-resolution, isotropic, nearly motion-free coronary imaging. Coronary stenoses are detected with high sensitivity and a normal scan accurately rules out the presence of a coronary stenosis. With the introduction of further novel concepts in CT-technology one may expect that MSCT-CA will become a clinically used diagnostic tool. Copyright © 2007 Wiley Periodicals, Inc. [source]