426 research outputs found
Church monuments of Devon and Cornwall c1660-c1730
Merged with duplicate record 10026.1/747 on 03.04.2017 by CS (TIS)This thesis is concerned with an analysis of church monuments in the south
west peninsular counties in the period 1660-1730 and sees the monument
within this region as a culturally significant object that has hitherto been
largely ignored. The focus of this thesis is an analysis of the monuments
themselves based on a photographic archive. This is complemented by an
examination of wills and the requests for monument and other status
indicators contained in those documents. The thesis also considers how the
placement of the monument is an indication of social status or status
pretensions and how the materials used in the manufacture of the
monument also have a status dimension.
Chapter 1 examines the available literature and establishes the methodology
of the project. Chapter 2 looks at issues surrounding wealth and
commemoration including the role of the church and the death ritual as
practised at that time. Chapter 3 considers the patterns of monument
distribution and also provides an analysis of the component parts of the
monument. Chapter 4 focuses on the work of artists and workshops and
shows that of the two major workshops working in the early seventeenth
century - John Weston of Exeter and the Jewells of Barnstaple - more
examples of their work have been identified as a result of this study. The
chapter also looks at examples of work from artists outside the region and
probable work from London yards has been identified. The final chapter looks
at issues surrounding social status. The interpretations of modern authors
are considered and the chapter goes on to show how status is expressed on
the monument. Patterns of distribution by social status are examined and an
analysis is provided of peninsular counties monuments based on social
status models
Cost of HPV screening at community health campaigns (CHCs) and health clinics in rural Kenya.
BACKGROUND:Cervical cancer is the most frequent neoplasm among Kenyan women, with 4800 diagnoses and 2400 deaths per year. One reason is an extremely low rate of screening through pap smears, at 13.8% in 2014. Knowing the costs of screening will help planners and policymakers design, implement, and scale programs. METHODS:We conducted HPV-based cervical cancer screening via self-collection in 12 communities in rural Migori County, Kenya. Six communities were randomized to community health campaigns (CHCs), and six to screening at government clinics. All HPV-positive women were referred for cryotherapy at Migori County Hospital. We prospectively estimated direct costs from the health system perspective, using micro-costing methods. Cost data were extracted from expenditure records, staff interviews, and time and motion logs. Total costs per woman screening included three activities: outreach, HPV-based screening, and notification. Types of inputs include personnel, recurrent goods, capital goods, and services. We costed potential changes to implementation for scaling. RESULTS:From January to September 2016, 2899 women were screened in CHCs and 2042 in clinics. Each CHC lasted for 30 working days, 10Â days each for outreach, screening, and notification. The mean cost per woman screened was 25.09; Range: 29.56 for clinics [25.27-37.08]. Clinics had higher costs than CHCs for personnel (11.26) and capital (2.80). Screening costs were higher for clinics at 17.48 for CHCs. In contrast, CHCs had higher outreach costs (0.17). After modeling a reduction in staffing, clinic per-screening costs ($25.69) were approximately equivalent to CHCs. CONCLUSIONS:HPV-based cervical cancer screening through community health campaigns achieved lower costs per woman screened, compared to screening at clinics. Periodic high-volume CHCs appear to be a viable low-cost strategy for implementing cervical cancer screening
The effect of corrosion morphology on the fatigue initiation and small crack growth behavior of AA7050-T7451
Complex airframe structures often require the use of stainless steel fasteners to assemble/join aluminum substructures. A galvanic couple is created when surface coatings/sealants are breached enabling ingress of an electrolyte; this leads to corrosion damage at these inherently high stress joints. Recent US Air Force studies have demonstrated that corrosion nucleated fatigue damage represents roughly 80% of airframe fatigue damage initiation sites [1]. Despite the critical importance of this failure mode the interaction of the mechanical and electrochemical interactions for a realistic galvanic couple configuration are poorly understood. This talk will report on a collaborative effort that aims to quantify the local galvanic environments, quantitatively characterize the corrosion morphology associated with such environments, and evaluate how such morphologies influence the fatigue behavior of a modern aerospace aluminum alloy. The primary focus will be on quantitatively evaluating the macro-features, micro-features, and microstructural interactions that govern the crack formation behavior and how the relative influence of each varies with different corrosion morphologies produced using electrochemical conditions pertinent to an in-service galvanic couple.
Leveraging collaborator inputs from experimental and computation analysis of the electrochemistry of a representative galvanic couple, three corrosion morphologies are considered: discrete pitting (small and large scale), a broadly corroded surface with surface recession and intergranular corrosion (IGC). Each damage morphology is induced on the SL surface of the AA7050-T7451 fatigue samples. Optical microscopy, white light interferometry, and x-ray computed tomography (XCT) are used to characterize the features of the corroded specimens. XCT is also used to identify the location of underlying constituent particles. Corroded specimens are fatigue loaded (σmax of 200 MPa, R of 0.5 and f of 20 Hz) along the L-direction in a high humidity (RH\u3e90%) that is maintained inside a plexiglass chamber. A programmed fatigue loading sequence is used mark the crack front intermittently on the fracture surface of the specimens; these fatigue-sequence induced marker bands are analyzed using the scanning electron microscope to quantify crack formation location and life ((Ni) to ≈10 μm) and crack growth rates (da/dN). Once fractography is complete the fracture surface is polished (roughly 15 μm deep) and electron back-scatter diffraction analysis is performed to enable characterization of the microstructure proximate to the crack formation site and how it intersects the growing small crack.
Overall fatigue life results show a substantial and similar reduction in fatigue life due to each of the corrosion morphologies; markerband analysis demonstrates that this strong reduction is primarily due to a vast decrease in the crack formation life. Similar small crack growth rates are observed proximate to each of the corrosion features. Analysis of the macro-features of the corrosion morphology show no clear trend between crack formation sites and the damage depth, width, 3D volume, density, or proximity to surrounding damage. Furthermore the similarity in the crack formation life between different morphologies suggests that the micro-features associated with each damage type results in a similarly deleterious local condition for crack formation. The proximity of local constituent particles and the local grain orientations are evaluated to determine if there is commonality between the crack formation location and a consistent microstructure feature(s).
The results and conclusion of this effort will quantitatively characterize the crack formation behavior of a relevant aerospace Al alloy in realistic conditions and leverage this data to further the mechanistic understanding of the factors governing the corrosion to fatigue crack transition. This understanding it critical to inform engineering scale prognosis strategies and provide guidance on the critical criteria for designing corrosion mitigation strategies in the context fatigue damage.
References:
[1] G.A. Shoales, S.A. Fawaz, M.R. Walters, in: M. Bos (Ed.) ICAF 2009 - Bridging the Gap Between Theory and Operational Practice, Springer, Rotterdam, The Netherlands, 2009, pp. 187-207
Understanding corrosion features and alloy microstructural effects on fatigue initiation of corroded AA7050-T7451 using data science
Aluminum alloy 7050-T451 is generally used in aerospace structure due to its high strength-to-weight ratio and high toughness. Local galvanic coupling set up by wicking of electrolyte in between the stainless steel fastener used in the aircrafts and the aluminum substructure promote corrosion of AA7050-T7451. Fatigue crack initiation tend to occur on discontinuities in the aluminum alloy such as the corrosion damage created by the galvanic coupling. Previous study indicate that the individual metrics analyzed for the macro-scale (\u3e250 μm) corrosion features such as pit depth, pit density, pit volume, area of the pit mouth, do not fully correlate to the location of the fatigue crack initiation [1]. The objective of this study is to verify if there is an interaction effect on the metrics analyzed using the macro-scale corrosion damage features using data science techniques. Another objective of this study is to determine if the micro-scale (\u3c250 μm) corrosion features and the alloy microstructure play an important role in the fatigue initiation mechanism of AA7050-T7451.
In order to understand the mechanism governing the fatigue crack formation, corrosion damage mimicking the galvanic coupling effect of AA7050-T7451 and SS316 are artificially created on the surface of AA7050-T7451. A small area on the LS surface of the fatigue specimens are exposed to different environmental conditions to create four different corrosion morphologies, namely, shallow and deep discrete pits, fissures and general corrosion with surface recession. These corrosion morphologies are characterized using the optical microscope, white light interferometer, scanning electron microscope and X-ray computed tomography. The specimens are subjected to fatigue loading using a special loading protocol that creates marker bands on the fracture surface. The specimens are cyclically loaded along the L-direction with σmax of 200 MPa, R ratio of 0.5 at a frequency of 20 Hz. The fatigue testing is done at 23°C and a controlled moist environment with \u3e90% relative humidity during the entire test. After fatigue testing, the fractographs of the specimens are obtained using the SEM. The marker bands from these fractographs are analyzed to calculate the crack growth rate and the fatigue initiation life to create a 10 μm crack from the initiation point are estimated.
Data science approaches are employed to analyze the interaction effect of the individual metrics reported in the macro-scale corrosion feature analysis. Random forest and logistic regression modeling show that there is minimal significance between the macro-scale corrosion feature predictor variables and the fatigue crack initiation points. Even though data science indicate that these factors have less significance, these factors should not be neglected. The micro-scale corrosion features and the distribution of secondary phase particles as well as the grain character are individually analyzed and correlated to the location of the fatigue crack initiation for all the corrosion damage morphologies. Results show that these individual metrics does not fully dictate the location of the fatigue crack initiation. Future work of this study involves the use of data science techniques to understand the relationship between the micro-scale corrosion features, their possible interaction with the alloy microstructure, and the fatigue crack formation. This study will provide understanding on what governs the fatigue crack initiation and inform current micro-mechanical models to incorporate effects of pertinent parameters in predicting remaining life of corroded specimens.
Reference:
[1] Co NEC, Burns JT. Effects of macro-scale corrosion damage feature on fatigue crack initiation and fatigue behavior. Int J Fatigue 2017;103:234–47. doi:10.1016/j.ijfatigue.2017.05.028
Localized Strain and Associated Failure of Structural Materials
Aircraft are made primarily out of strong and lightweight aluminum alloys, which are relatively low cost, easy to produce, and have allowed for several innovations in the airplane industry. Even though these alloys are highly corrosion resistant, they are susceptible to failure since airplanes experience some of the harshest fatigue and corrosion conditions. Predicting the location of crack initiation on these corroded materials could lead to preventative safety of aluminum components on an aircraft. To study the mechanisms leading to cracking, precorroded AA7050 samples were fatigue loaded to failure, virtually reconstructed form post-mortem characterizations, and modeled accordingly to obtain the micromechanical state of the material. Fatigue indicator parameters were calculated from the resulting stresses and strains. The initial corrosion front was then analyzed at the reconstructed crack plane, using a metric that identifies the most active slip planes per grain. The reconstructed data is masked over onto planes that have the same orientation as the [111] slip planes. Then, the data is analyzed quantitatively for each slip plane, looking for the highest median fatigue indicator parameter value. The slip plane on the grain closest to the crack initiation site was found to have a slip plane roughly parallel to the crack plane. On this plane, many significantly larger fatigue indicator parameter values were found, with the highest value pinpointing the region where crack initiation was experimentally observed
ALLN-177, oral enzyme therapy for hyperoxaluria
PURPOSE:
To evaluate the potential of ALLN-177, an orally administered, oxalate-specific enzyme therapy to reduce urine oxalate (UOx) excretion in patients with secondary hyperoxaluria.
METHODS:
Sixteen male and female subjects with both hyperoxaluria and a kidney stone history were enrolled in an open-label study. Subjects continued their usual diets and therapies. During a 3-day baseline period, two 24-h (24-h) urines were collected, followed by a 4-day treatment period with ALLN-177 (7,500 units/meal, 3 × day) when three 24-h urines were collected. The primary endpoint was the change in mean 24-h UOx from baseline. Safety assessments and 24-h dietary recalls were performed throughout.
RESULTS:
The study enrolled 5 subjects with enteric hyperoxaluria and 11 with idiopathic hyperoxaluria. ALLN-177 was well tolerated. Overall mean (SD) UOx decreased from 77.7 (55.9) at baseline to 63.7 (40.1) mg/24 h while on ALLN-177 therapy, with the mean reduction of 14 mg/24 h, (95% CI - 23.71, - 4.13). The calcium oxalate-relative urinary supersaturation ratio in the overall population decreased from a mean of 11.3 (5.7) to 8.8 (3.8) (- 2.8; 95% CI - 4.9, - 0.79). This difference was driven by oxalate reduction alone, but not any other urinary parameters. Mean daily dietary oxalate, calcium, and fluid intake recorded by frequent diet recall did not differ by study periods.
CONCLUSION:
ALLN-177 reduced 24-h UOx excretion, and was well tolerated. The results of this pilot study provided justification for further investigation of ALLN-177 in patients with secondary hyperoxaluria
WTEC panel report on European nuclear instrumentation and controls
Control and instrumentation systems might be called the 'brain' and 'senses' of a nuclear power plant. As such they become the key elements in the integrated operation of these plants. Recent developments in digital equipment have allowed a dramatic change in the design of these instrument and control (I&C) systems. New designs are evolving with cathode ray tube (CRT)-based control rooms, more automation, and better logical information for the human operators. As these new advanced systems are developed, various decisions must be made about the degree of automation and the human-to-machine interface. Different stages of the development of control automation and of advanced digital systems can be found in various countries. The purpose of this technology assessment is to make a comparative evaluation of the control and instrumentation systems that are being used for commercial nuclear power plants in Europe and the United States. This study is limited to pressurized water reactors (PWR's). Part of the evaluation includes comparisons with a previous similar study assessing Japanese technology
Flight Operations Analysis Tool
Flight Operations Analysis Tool (FLOAT) is a computer program that partly automates the process of assessing the benefits of planning spacecraft missions to incorporate various combinations of launch vehicles and payloads. Designed primarily for use by an experienced systems engineer, FLOAT makes it possible to perform a preliminary analysis of trade-offs and costs of a proposed mission in days, whereas previously, such an analysis typically lasted months. FLOAT surveys a variety of prior missions by querying data from authoritative NASA sources pertaining to 20 to 30 mission and interface parameters that define space missions. FLOAT provides automated, flexible means for comparing the parameters to determine compatibility or the lack thereof among payloads, spacecraft, and launch vehicles, and for displaying the results of such comparisons. Sparseness, typical of the data available for analysis, does not confound this software. FLOAT effects an iterative process that identifies modifications of parameters that could render compatible an otherwise incompatible mission set
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