Study of acoustic emission during mechanical tests of large flight weight tank structure

A polyphenylane oxide insulated, flight weight, subscale, aluminum tank was monitored for acoustic emissions during a proof test and during 100 cycles of environmental test simulating space flights. The use of a combination of frequency filtering and appropriate spatial filtering to reduce background noise was found to be sufficient to detect acoustic emission signals of relatively small intensity expected from subcritical crack growth in the structure. Several emission source locations were identified, including the one where a flaw was detected by post-test X-ray inspections. For most source locations, however, post-test inspections did not detect flaws; this was partially attributed to the higher sensitivity of the acoustic emission technique than any other currently available NDT method for detecting flaws

A synthesis of sand seas throughout the world

There are no author-identified significant results in this report

Evidence for the Gompertz Curve in the Income Distribution of Brazil 1978-2005

This work presents an empirical study of the evolution of the personal income distribution in Brazil. Yearly samples available from 1978 to 2005 were studied and evidence was found that the complementary cumulative distribution of personal income for 99% of the economically less favorable population is well represented by a Gompertz curve of the form $G(x)=\exp [\exp (A-Bx)]$, where $x$ is the normalized individual income. The complementary cumulative distribution of the remaining 1% richest part of the population is well represented by a Pareto power law distribution $P(x)= \beta x^{-\alpha}$. This result means that similarly to other countries, Brazil's income distribution is characterized by a well defined two class system. The parameters $A$, $B$, $\alpha$, $\beta$ were determined by a mixture of boundary conditions, normalization and fitting methods for every year in the time span of this study. Since the Gompertz curve is characteristic of growth models, its presence here suggests that these patterns in income distribution could be a consequence of the growth dynamics of the underlying economic system. In addition, we found out that the percentage share of both the Gompertzian and Paretian components relative to the total income shows an approximate cycling pattern with periods of about 4 years and whose maximum and minimum peaks in each component alternate at about every 2 years. This finding suggests that the growth dynamics of Brazil's economic system might possibly follow a Goodwin-type class model dynamics based on the application of the Lotka-Volterra equation to economic growth and cycle.Comment: 22 pages, 15 figures, 4 tables. LaTeX. Accepted for publication in "The European Physical Journal B

Nagaland: Borders, Boundaries, Belonging: Contested spaces and disputed narratives

In 2011 I travelled to three of the ‘Seven Sister’ states of old Assam, Nagaland, Meghalaya & Assam. My journey to this remote and politically sensitive region, bordering Chinese occupied Tibet, Bangladesh and Myanmar was prompted by my father’s experiences in the region during WW2 in the Burma Campaign and brought into sharp relief on-going themes in my work, the impact the past has on the present, the relationship of time and place, identity and memory and the transcultural experiences caused by war, colonisation and migration. The drawings I made on location, the objects I collected and the notes and photographs I took formed the basis of the bookwork: NAGALAND borders boundaries belonging. When making the finished work the material quality of the object and the processes by which it was made become very important. The historical resonance of the medium and the time consuming nature of the process reflect the embedding of form and idea, and paid homage to the material culture of the Naga hill tribes. The bookwork was hand-bound, handset and printed by letterpress. Some spreads were printed in 6 colours and the book took over a year to produce. I see my practice as echoing that of generations of Lady travellers; embracing the need to journey, be in a liminal space, to have a plan but not be afraid to divert from it. To be alone, take a sketchbook and make images is, for me, the definition of the itinerant illustrator; one who travels widely in geographic space, visual forms and ideas, in order to get lost and find the unlooked for

The Effect of Student Lifestyle on Days Depressed

The purpose of our paper is to discover what factors about student lifestyles affect how often students experience symptoms of depression, using anonymous survey results from 96 George Fox students. We will explore if how many days a student is depressed per month might be determined by factors such as the number of hours spent in a week doing schoolwork, working, doing something enjoyable, social media usage and their housing status. We determined that our sample of 96 was representative enough of the George Fox undergraduate student population to be able to use in our regressions. Additionally, we found that our data was reasonable to use because it met the assumption criteria for linearity, homoscedasticity, and normality of errors. Through our research we ultimately found four factors that were significant in determining the number of days students are depressed per month: time doing schoolwork, time with friends, time doing something enjoyable, hours of sleep, and living on or off campus

Autonomic physiological data associated with simulator discomfort

The development of a physiological monitoring capability for the Army's advanced helicopter simulator facility is reported. Additionally, preliminary physiological data is presented. Our objective was to demonstrate the sensitivity of physiological measures in this simulator to self-reported simulator sickness. The data suggested that heart period, hypergastria, and skin conductance level were more sensitive to simulator sickness than were vagal tone and normal electrogastric activity

Origin of the Second-Order Proton Catalysis of Ferriin Reduction in Belousov-Zhabotinsky Reactions: Density Functional Studies of Ferroin and Ferriin Aggregates with Outer Sphere Ligands Sulfate, Bisulfate, and Sulfuric Acid

The detailed mechanisms of Belousov-Zhabotinsky oscillating reactions continue to present grand challenges, even after half a century of study. The origin of the pH dependence of the oscillation pattern had never been rigorously identified. In our recent kinetic study of one of the key Belousov-Zhabotinsky reactions, the iron-catalyzed bromate oxidation of malonic acid, compelling agreement between experiments and kinetic simulations was achieved only with the inclusion of second-order proton catalysis of the reduction of the [Fe(phen)3]3+ species. After exhausting all other avenues in search of an explanation of this proton catalysis, we considered the possibility that the parent iron-phenanthroline complexes could aggregate with neutral and anionic outer sphere ligands (OSLs) in the highly concentrated sulfuric acid solution, and we hypothesized that OSL protonation would increase the capacity of the aggregated complex to oxidize the organic fuel. We performed potential energy surface analyses at the SMD(APFD/6-311G*) level of complexes of the types [Fe(phen)3(SO42-)m(HSO4-)n(H2SO4)o](c-2m-n)+ for ferriin (c = 3) and ferroin (c = 2) aggregated with m sulfate, n bisulfate, and o sulfuric acid OSLs. We present structures of the OSL aggregates, develop a nomenclature for their description, and characterize their electronic structure. The structural chemistry provides the foundation to discuss the ferroin/ferriin redox couple with emphasis on the relationship between the vertical electron affinities of ferriin aggregates and their OSL protonation states. For proton catalysis to manifest itself, double-protonation paths that are slightly endergonic should be present, and proton affinities of aggregated OSLs allow the identification of such double-protonation chains. As a first test of our mechanistic proposal for the second-order proton catalysis of the Belousov-Zhabotinsky reaction, the results presented here provide compelling evidence in support of the importance of outer sphere ligation of the iron catalyst