A case of drag reduction and pressure pulsations in pneumatic conveying

Experimental pressure drop results have been obtained for dilute phase pneumatic conveying of ordinary portland cement in a 100 mm diam. horizontal pipe with a test section length of 18 m.Significant drag reduction was detected in the presence of pressure pulsations introduced into the flow by a Roots type blower. Suppression of the pressure pulsations eliminated drag reduction.Compared with steady flow condition, it was found that pressure pulsations had a stabilising influence on the flow, permitting a 32% higher solids feed rate to be obtained before the formation of a stationary bed and the onset of unstable flow.Drag reduction in the test section was obtained at the expense of an increased pressure drop in the mixing and solids acceleration zones.     

Static team problems--Part I: Sufficient conditions and the exponential cost criterion

The stationary conditions of Radner are shown under relaxed hypotheses to be sufficient to establish the global optimality of candidate control laws for static team problems with convex cost. This extension of Radner's theorem establishes the optimality of affine laws for the exponential of a quadratic performance index with jointly Gaussian state and observation variables. The class of performance indexes of team problems for which the optimal solution is known is thereby enlarged.     

Compact CO2 laser for infrared heterodyne radar

A compact CO(2) laser has been developed for field use as part of an infrared heterodyne radar. The laser, which contains a separate local oscillator, transmits 10.5 W cw or 7 W average in the electrooptically Q-switched mode at a repetition rate of 50 kHz. The applicability of this laser to active imaging is discussed.     

Measurement of polydispersity of ultra-narrow polymer fractions by thermal field-flow fractionation

In this paper we demonstrate that the polydispersity µ = M?_w/M?_N of narrow polymer fractions can be readily obtained by measuring band broadening and its velocity dependence in a thermal field–flow fractionation (thermal FFF) system. The thermal FFF method is shown to be more accurate than size exclusion chromatography for the determination of polymer polydispersities due to the simpler band dispersion function and the higher selectivity inherent to the technique. The polydispersities of a series of four narrow polystyrene samples prepared by anionic polymerization were consequently determined by thermal FFF and found to be much smaller (1.003–1.006) than the ceiling values (1.06) suggested by the suppliers. As part of this investigation, an experimental study of band dispersion in thermal FFF is used to examine current theory. The data show nonequilibrium to be the dominant factor, whereas relaxation effects are insignificant at lower flow rates and can be subdued at higher flow rates. A high correlation between nonequilibrium theory and experiment allows for the estimation of diffusion coefficients from plate height–velocity data.     

Electrodermal nonresponding, premorbid adjustment, and symptomatology as predictors of long-term social functioning in schizophrenics.

The hypothesis that electrodermal nonresponsiveness to orienting stimuli delineates a core group of "Kraepelinian" type schizophrenics was tested by following up social functioning outcome over a 2-year period in 37 schizophrenics. Good social functioning outcome required both some self-supporting ability in the job market and a minimal social life. The prior assessments included monitoring of electrodermal responses to a series of moderately intense tones, ratings of reported and observed symptoms during an interview, and ratings of premorbid adjustment on the basis of an interview with a close relative. Electrodermal nonresponding, poor premorbid adjustment, and negative symptomatology predicted poor social functioning during the second follow-up year, but the relationship to nonresponding pertained exclusively to a group of 15 first-episode patients. Discriminant analysis showed that electrodermal nonresponding and symptoms were the only independent predictors of outcome. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relative pressure estimation from 4D flow MRI using generalized Bernoulli equation in a phantom model of arterial stenosis

Magnetic Resonance Materials in Physics, Biology and Medicine - Arterial stenosis is a significant cardiovascular disease requiring accurate estimation of the pressure gradients for determining...     

The Influence of Alloying Elements on Impurity Induced Grain Boundary Embrittlement

A nonequilibrium thermodynamic model which describes the effect of solute grain boundary segregation on grain boundary cohesion was extended to Fe ternary systems. The extended model directly and simply predicts the effect of alloying elements on impurity-induced grain boundary embrittlement. According to the extended model, Mo, W, and Zr strongly reduce, Ni, Ti, and V slightly reduce, and Cr and Mn enhance impurity-induced grain boundary embrittlement in an Fe ternary system. For the evaluation of the extended model, Fe-P, Fe-P-Mn, Fe-P-Mo, and Fe-P-W alloys were studied by Auger electron spectroscopy, scanning electron microscopy, 4-point slow bend tests, and tension tests. The experimental results show that for a given amount of P grain boundary segregation the grain boundary strength increases with increasing Mo or W grain boundary segregation and decreases with increasing Mn grain boundary segregation. These experimental results showing the remedial effect of Mo or W and the embrittling effect of Mn on P-induced grain boundary embrittlement are consistent with the predicted results from the extended model. The nonequilibrium model is also used to evaluate impurity-induced interfacial embrittlement in continuous fiber metal matrix composite materials.     

Back-scattered electron imaging for leakage analysis of four retrofilling materials

This study aimed to evaluate, ex vivo, the nanoleakage in dentinal tubules, the linear infiltration of silver nitrate in the dentin wall/root-end filling material interface, and the presence of gaps in this interface in root-end cavities filled with 4 filling materials. Forty-eight disto-buccal root canals of maxillary molars were instrumented and filled. Retrograde cavities were prepared with ultrasonic points (apical 2 mm). The samples were divided into 2 control groups (n = 4) and 4 experimental groups (n = 10): Group I--white mineral trioxide aggregate (MTA); Group II--Super EBA; Group III--Portland cement; and Group IV--Sealer 26. After 1 week, the specimens were subjected to silver nitrate and prepared for SEM (backscattered electrons). In the apical-apical segment, an area with significantly higher leakage was observed for Super EBA, followed by Portland cement, MTA, and Sealer 26 (P = 0.0054). In the medium and cervical segments, all materials showed the same leakage behavior (P = 0.1815 and P = 0.1723, respectively). The linear infiltration at the dentin wall/root-end filling material interface was higher with Super EBA than the other groups. No differences in the percentage of gaps along the 3 mm of dentin wall/root-end filling material interface between the 4 materials were evident (P > 0.05). Nanoleakage occurred mainly in the apical segment of the samples, and Super EBA showed the highest values. The area and linear leakage were lower in the middle and coronal segments, regardless of the root-end filling material. No material perfectly sealed the root-end cavities, which allowed for the leakage occurrence.     

A Software Agent Architecture for Network Management: Case Studies and Experience Gained

Current Network Management paradigms are rigid and lack flexibility. This makes the task of managing a highly evolving and dynamic network difficult to cope with. This paper presents the results of our work on Agent technology as a new paradigm for developing Network Management applications. First, we present our agent architecture that is built in a way that allows the agent to acquire new capabilities at runtime. Second, we present two case studies implemented with a prototype of this agent architecture. The first case study consists of an agent system in which faulty agents are automatically detected, their tasks then being reallocated to other agents, thus providing a fault-tolerant management system. The second case study deals with the configuration of heterogeneous ATM networks to establish end-to-end permanent virtual channels. Finally, we evaluate our agent architecture and the agent paradigm in general when applied to Network Management.     

Model selection with the Loss Rank Principle

A key issue in statistics and machine learning is to automatically select the “right” model complexity, e.g., the number of neighbors to be averaged over in k nearest neighbor () regression or the polynomial degree in regression with polynomials. We suggest a novel principle-the Loss Rank Principle (LoRP)-for model selection in regression and classification. It is based on the loss rank, which counts how many other (fictitious) data would be fitted better. LoRP selects the model that has minimal loss rank. Unlike most penalized maximum likelihood variants (AIC, BIC, MDL), LoRP depends only on the regression functions and the loss function. It works without a stochastic noise model, and is directly applicable to any non-parametric regressor, like .