On the internal structure of weakly nonlinear bores in laminar high Reynolds number flow

The paper deals with the internal structure of hydraulic jumps in near-critical single-layer flows which replaces the discontinuities predicted by hydraulic theory if viscous effects acting inside a thin laminar boundary layer are properly accounted for. In the limit of large Reynolds number this leads to a structure problem formed by the classical triple-deck equations supplemented with a novel nonlinear interaction relationship which allows for the passage through the critical state. Hydraulic jumps are shown to represent eigensolutions of the structure problem where this passage is achieved by the local thickening of the boundary layer which acts as a viscous hump. The effects of detuning and dispersion due to streamline curvature and surface tension on the internal structure of hydraulic jumps are studied in detail. In addition, the interaction of hydraulic jumps with surface mounted obstacles is investigated.     

Analysis of the Design-Build Delivery Method in Air Force Construction Projects

The design-build (DB) method for construction project delivery continues to grow in both the private and public sector; additionally, research has shown that the DB method outperforms the design-bid-build (DBB) method. The Air Force has applied the results of these previous research efforts to its military construction (MILCON) program without performing empirical studies to validate the approach. Therefore, the objective of this study was to compare the performance of the DB delivery method with the traditional DBB approach for the Air Force MILCON program. Data related to 835 (278 DB and 557 DBB) MILCON projects for fiscal years 1996–2006 were subsequently analyzed. The DB method had better performance in three of six metrics with the performance being significantly better for cost growth and the number of modifications per million dollars. The traditional DBB method performed significantly better in terms of total project time. Furthermore, the DB method was best suited for various facility types. This study provides empirical evidence of how the DB method provides an advantage over the traditional DBB method for Air Force MILCON projects.     

Iterative algorithm for optimal fiducials under weak perspective projection

In previous work, we designed space fiducials with the aim of making camera pose determination as noise‐insensitive as possible. These fiducials turned out to be sets of points that formed concentric regular polyhedra. Here, we apply an idea of Dementhon and Davis and test and analyze an iterative linear algorithm in conjunction with our optimal fiducials to increase the accuracy of the computed camera pose. We also analyze under what circumstances this iterative algorithm is guaranteed to converge to the correct solution. Comprehensive computer simulations illustrate the behavior of the algorithm and the degree of improvement in pose determination in case of convergence. © 2009 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 19, 27–36, 2009     

Direct numerical inversion method for kinetic ellipsometric data. I. Presentation of the method and numerical evaluation

A direct numerical inversion method for the determination of the refractive index and the thickness of the outermost layer of a thin transparent film on top of a multilayer has been developed. This method is based on a second-order Taylor decomposition of the coefficients of the Abelès matrices of the newly grown layer. The variations of the real-time spectroscopic ellipsometry data are expressed as polynomial fuctions depending on the dielectric constant and the thickness of the newly grown layer. The method is fast, capable of single-wavelength and multiwavelength inversion of continuous as well as discontinuous-index profiles, and can be adapted to many different polarimetric instruments.     

Identifying clinical syndromes in a community sample of elderly persons.

By a strategy suggested by E. H. Uhlenhuth et al (1983), Diagnostic and Statistical Manual of Mental Disorders (DSM-III) referenced syndrome classifications were derived on the basis of the Hopkins Symptoms Checklist—42 scores of 1,131 elderly community residents. Overall syndrome prevalence rates were consistent with other epidemiologic data: 3.9% for depression, 1.0% for agoraphobia-panic, 2.6% for other phobia, and 6.9% for anxiety. Prevalence rates reflected expected sex differences and showed an age trend for other phobias. Considerable comorbidity among syndromes was observed. The association of the syndromes with patterns of psychosocial risk factors, prior diagnoses, and medication suggests that some but not all of the identified syndromes reflect clinically relevant classifications. If further developed, syndrome classifications based on self-report scales can provide inexpensive and clinically relevant measures of caseness. Required refinements of this approach are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mechanism of shear modification of low density polyethylene

In this paper we address the aspects associated with shear modification of low density polyethylene by extrusion. By successive passes of the polymer through an extruder it can be shown that both the melt viscosity and melt elasticity are reduced by shear modification. These reversible variations are not accompanied by significant changes in molecular weight distribution. The major effects of extrusion are to decrease the amount of elastically effecitve material. Study of proton relaxation times at 150°C shows that the melt comprises regions of relatively ordered, entangled, and unentangled polymer. Shearing reduces the proportion of more ordered material. The elastically effective anchors that are reduced by shearing are regions with restricted segmental mobility rather than conventional entanglements or intermolecular knots. Successive extrusions produce a relatively small decrease in the number of such constraints to molecular motion. Repeated shearing has a diminishing effect on the proportion of more ordered material in the polyethlene melt. This parallels observations of the effects of repeated shear modification on the properties of polyethylene films and other extrudates.     

Computability,complexity and economics

Herbert Simon advocates that economists should study procedureal rationality instead of substantive rationality. One approach for studying procedural rationality is to consider algorithmic representations of procedures, which can then be studied using the concepts of computability and complexity. For some time, game theorists have considered the issue of computability and have employed automata to study bounded rationality. Outside game theory very little research has been performed. Very simple examples of the traditional economic optimization models can require transfinite computations. The impact of procedural rationality on economics depends on the computational resources available to economic agents.