Quantitative assessment of preferential fatigue initiation sites in a multi‐phase aluminium alloy

Complex multi‐phase Al–Sn–Si alloys are commonly employed in the manufacture of small automotive plain bearings. The fundamental fatigue initiation behaviour of this class of alloys is currently not well understood. A range of analytical techniques were applied to investigate preferential initiation site location and to attempt to identify critical microstructural features. It was apparent from experimental studies that points of fatigue crack initiation are associated with the Si secondary phase. Using tessellation approaches and subsequently both adaptive numerical modelling and micro‐scale finite element modelling allowed the identification of features affecting the probability that a given Si phase would initiate a fatigue crack.     

Equilibrium Cation Distribution in NiAl2O4, CuAl2O4, and ZnAl2O4 Spinels

Stoichiometric NiAl₂O₄, CuAl₂O₄, and ZnAl₂O₄ spinels were prepared and equilibrated at temperatures from 600° to 1400°C. The parameters u and x , denoting the oxygen position and fraction of divalent cations on tetrahedral sites, respectively, were determined from a detailed X-ray diffraction analysis. In NiAl₂O₄, x increased from 0.07 at 595° to 0.26 at 1391°C; in CuAl₂O₄, x decreased from 0.68 at 613° to 0.64 at 1195°C; and in ZnAl₂O₄, x decreased from 0.96 at 905° to 0.94 at 1197°C. The form of the temperature dependence of x could not be described using theoretically based equations advanced in the literature. A more general equation which allows for a non-distributional contribution to the configurational entropy was derived and observed to properly describe the temperature dependence; the results indicate that short-range order is of definite significance in these intermediate aluminate spinels.     

A comparison between two photographic methods for the determination of relative bidirectional reflectance

Two simple photographic methods have recently been proposed for the measurement of relative bidirectional reflectance (Lillesand and Kiefer 1979, Curran 1980). These two methods were used to calculate the relative bidirectional reflectance of ten contrasting surfaces. The photographic relative bidirectional reflectance so recorded, was then compared with the radiometric bidirectional reflectance for each surface. Two conclusions were drawn: first, that relative bidirectional reflectance can be measured using these simple photographic techniques, and second, that there was no significant difference between the Lillesand and Kiefer and Curran methods for photographically deriving relative bidirectional reflectance.     

URBAN BUILT ENVIRONMENTS,ACCESSIBILITY, AND TRAVEL BEHAVIOR IN A DECLINING URBAN CORE: THE EXTREME CONDITIONS OF DISINVESTMENT AND SUBURBANIZATION IN THE DETROIT REGION

The research explores the impact of socioeconomic and racial variables on accessibility to urban amenities and travel in compact urban built environments that have traditionally been viewed as improving access to daily destinations and promoting nonmotorized travel: urban environments characterized by high densities, mixed land uses, and high connectivity. The study focuses on six neighborhoods in the Detroit region. Two neighborhoods are within the city itself, and predominantly poor and Black, and four of the neighborhoods are in the region surrounding the city, and they are predominantly wealthy and White. This study at the neighborhood scale enables an analysis into how class and race affect accessibility and travel in neighborhoods experiencing urban disinvestment and decline. The research shows that the traditional relationship between high densities, mixed land uses, high connectivity, greater accessibility, and pedestrian activity is significantly weaker in declining inner cities.     

GENITOR II: a distributed genetic algorithm

Abstract

GENITOR is a genetic algorithm which employs one-at-a-time reproduction and allocates reproductive opportunities according to rank to achieve selective pressure. Theoretical arguments and empirical evidence suggest that GENITOR is less vulnerable to some of the biases that degrade performance in standard genetic algorithms.

A distributed version of GENITOR which uses many smaller distributed populations in place of a single large population is introduced. GENITOR II is able to optimize a broad range of sample problems more accurately and more consistently than GENITOR with a single population. GENITOR II also appears to be more robust than a single population genetic algorithm, yielding better performance without parameter tuning. We present some preliminary analyses to explain the performance advantage of the distributed algorithm. A distributed search is shown to yield improved search on several classes of problems, including binary encoded feedforward neural networks, the Traveling Salesman Problem, and a set of ‘ deceptive problems’ specially designed to be hard for genetic algorithms.     

OFF TO MARKET: NEIGHBORHOOD AND INDIVIDUAL EMPLOYMENT BARRIERS FOR WOMEN IN 21ST CENTURY AMERICAN CITIES*

ABSTRACT: This paper endeavors to create a better understanding of the barriers to employment faced by disadvantaged urban women in the post–welfare reform era. Using data from the Project on Devolution and Urban Change, a unique geographically linked, longitudinal, multicity set of survey data, logistic regression models weighs the relative importance of individual barriers to employment (e.g., poor health, childcare, family responsibilities) and contextual or neighborhood barriers to employment (e.g., poverty rate, joblessness rate) on labor market outcomes. Results reveal that several neighborhood characteristics are predictive of employment outcomes, including automobile access, female‐headedness, vacancy, and disorder. Results suggest a more complex, nuanced interplay between neighborhood‐level variables and individually measured variables in preventing some women from obtaining both modestly paying employment with few allocated hours of work per week, and also better‐paying jobs with more hours of work per week.     

FOLLOWING THE MONEY: THE INFLUENCE OF CAMPAIGN FINANCE REFORM IN THE 2011 CHICAGO MAYORAL ELECTION

In this research we study the effect of recently enacted campaign contribution limits in Illinois via an examination of the 2011 Chicago mayoral election. Because contribution limits for state and local campaigns were implemented in the middle of the race for mayor we are uniquely positioned to test the efficacy of the new law. In theory we expect contribution limits to cause candidates to rely on more contributors making smaller donations. Our results indicate that the reform measure did not prompt candidates to broaden their fundraising base, and only when Rahm Emanuel's campaign is considered alongside his opponents’ did the fundraising law reduce average contributions. In a concluding section we address the issue of whether the contribution limits established under the law are too high to produce meaningful reform.     

The evaluation of underarm deodorants

Double-blind cross-over trials in which trained assessors evaluated axillary malodour on a 0 to 10 scale showed that ethanol at 60% and 99% w/w significantly reduced odour for up to 24 h. Reduction in odour was increased by the addition of non-volatile antimicrobial ingredients such as chlorhexidine, Irgasan DP 300 (Triclosan, Ciba Geigy) or aluminium chlorhydrate.
Volunteer panellists were able to identify statistically significant deodorant effects when they rated their own axillary odour on a 0 to 10 scale.
An odour absorber, zinc ricinoleate (Grillocin, Grillo-Werke, A. G.) was used to treat existing malodour and gave reduced perception of that malodour for up to 24 h.
A close correlation was found between panel odour scores and the bacterial status of the axilla as assessed by the replipad technique when biocidal systems were studied. Irgasan DP 300, a bacteriostat, did not perform so well in skin flora sampling procedures, but was nevertheless effective as a deodorant ingredient. Thus in vivo microbiological techniques, although often useful as predictors of deodorancy, do not replace the carefully controlled clinical trial with direct assessment of odour.
L'evaluation de l'odeur des aisselles     

Optical Absorption Spectra of Cr3+ in MgO·Al2O3-MgO·3.5Al2O3 Spinels

Spinel crystals in the system MgO· n Al₂O³:Cr³⁺ (1.04≤ n ≤3.51) were synthesized by flame fusion; their absorption spectra were measured in transmission from 400 to 50,000 cm⁻¹. The O-H band spectra suggest the presence of protons in octahedral site vacancies which appear for n >1. The spectra for Cr³⁺ indicate clearly that these ions occupy only octahedral sites. However, the effective trigonal field, which varies with n , causes the major absorption bands to split in the form of a lower-energy shoulder on a higher-energy component. The red-green transition in these spinels was rationalized and observed to arise from a somewhat different mechanism than that in other oxides in which the site radii and Cr³⁺ concentration vary considerably.     

Mechanics of Pressure Slip Casting

The quantitative mechanics of pressure slip casting an aqueous Al₂O₃ slip deflocculated with an organic polyelectrolyte were investigated at 50 to 500 psi. The specific resistance, casting rate, and microstructural characteristics of the resultant cakes were especially sensitive to the electrophoretic mobility of the slip. The mechanochemical action of the polyelectrolyte in effecting deflocculation was somewhat different from that of simple ionic electrolytes.