Mechanical features of the shuttle rotating service structure

With the development of the space shuttle launching facilities, it became mandatory to develop a shuttle rotating service structure to provide for the insertion and/or removal of payloads at the launch pads. The rotating service structure is a welded tubular steel space frame 189 feet high, 65 feet wide, and weighing 2100 tons. At the pivot column the structure is supported on a 30 inch diameter hemispherical bearing. At the opposite terminus the structure is supported on two truck assemblies each having eight 36 inch diameter double flanged wheels. The following features of the rotating service structure are discussed: (1) thermal expansion and contraction; (2) hurricane tie downs; (3) payload changeout room; (4) payload ground handling mechanism; (5) payload and orbiter access platforms; and (6) orbiter cargo bay access

Design and commission of an experimental test rig to apply a full-scale pressure load on composite sandwich panels representative of aircraft secondary structure

This paper describes the design of a test rig, which is used to apply a representative pressure load to a full-scale composite sandwich secondary aircraft structure. A generic panel was designed with features to represent those in the composite sandwich secondary aircraft structure. To provide full-field strain data from the panels, the test rig was designed for use with optical measurement techniques such as thermoelastic stress analysis (TSA) and digital image correlation (DIC). TSA requires a cyclic load to be applied to a structure for the measurement of the strain state; therefore, the test rig has been designed to be mounted on a standard servo-hydraulic test machine. As both TSA and DIC require an uninterrupted view of the surface of the test panel, an important consideration in the design is facilitating the optical access for the two techniques. To aid the test rig design a finite element (FE) model was produced. The model provides information on the deflections that must be accommodated by the test rig, and ensures that the stress and strain levels developed in the panel when loaded in the test rig would be sufficient for measurement using TSA and DIC. Finally, initial tests using the test rig have shown it to be capable of achieving the required pressure and maintaining a cyclic load. It was also demonstrated that both TSA and DIC data can be collected from the panels under load, which are used to validate the stress and deflection derived from the FE model

Full-scale performance assessment of aircraft secondary sandwich structure using thermoelastic stress analysis

The use of resin film infusion (RFI) has been proven to reduce the cost of production of aircraft secondary sandwich structure. In this paper thermoelastic stress analysis (TSA) is used to assess the performance of full scale aircraft sandwich structure panels produced using both the conventional autoclave process and RFI. Finite element (FE) models of both panel types are developed and TSA is used to validate the models

Clinical manifestations of human brucellosis : a systematic review and meta-analysis

BACKGROUND: The objectives of this systematic review, commissioned by WHO, were to assess the frequency and severity of clinical manifestations of human brucellosis, in view of specifying a disability weight for a DALY calculation. METHODS/PRINCIPAL FINDINGS: Thirty three databases were searched, with 2,385 articles published between January 1990-June 2010 identified as relating to human brucellosis. Fifty-seven studies were of sufficient quality for data extraction. Pooled proportions of cases with specific clinical manifestations were stratified by age category and sex and analysed using generalized linear mixed models. Data relating to duration of illness and risk factors were also extracted. Severe complications of brucellosis infection were not rare, with 1 case of endocarditis and 4 neurological cases per 100 patients. One in 10 men suffered from epididymo-orchitis. Debilitating conditions such as arthralgia, myalgia and back pain affected around half of the patients (65%, 47% and 45%, respectively). Given that 78% patients had fever, brucellosis poses a diagnostic challenge in malaria-endemic areas. Significant delays in appropriate diagnosis and treatment were the result of health service inadequacies and socioeconomic factors. Based on disability weights from the 2004 Global Burden of Disease Study, a disability weight of 0.150 is proposed as the first informed estimate for chronic, localised brucellosis and 0.190 for acute brucellosis. CONCLUSIONS: This systematic review adds to the understanding of the global burden of brucellosis, one of the most common zoonoses worldwide. The severe, debilitating, and chronic impact of brucellosis is highlighted. Well designed epidemiological studies from regions lacking in data would allow a more complete understanding of the clinical manifestations of disease and exposure risks, and provide further evidence for policy-makers. As this is the first informed estimate of a disability weight for brucellosis, there need for further debate amongst brucellosis experts and a consensus to be reache

Improved throat inserts for ablative thrust chambers

Composite material development and structural design of improved throat inserts for ablative thrust chamber

High-resolution 3D weld toe stress analysis and ACPD method for weld toe fatigue crack initiation

Weld toe fatigue crack initiation is highly dependent on the local weld toe stress-concentrating geometry including any inherent flaws. These flaws are responsible for premature fatigue crack initiation (FCI) and must be minimised to maximise the fatigue life of a welded joint. In this work, a data-rich methodology has been developed to capture the true weld toe geometry and resulting local weld toe stress-field and relate this to the FCI life of a steel arc-welded joint. To obtain FCI lives, interrupted fatigue test was performed on the welded joint monitored by a novel multi-probe array of alternating current potential drop (ACPD) probes across the weld toe. This setup enabled the FCI sites to be located and the FCI life to be determined and gave an indication of early fatigue crack propagation rates. To understand fully the local weld toe stress-field, high-resolution (5 mu m) 3D linear-elastic finite element (FE) models were generated from X-ray micro-computed tomography (mu-CT) of each weld toe after fatigue testing. From these models, approximately 202 stress concentration factors (SCFs) were computed for every 1 mm of weld toe. These two novel methodologies successfully link to provide an assessment of the weld quality and this is correlated with the fatigue performance

Mid-level African-American women administrators in higher education institutions : struggles and strategies.

Mid-level management is often overlooked in studies of higher education administration. African-American women mid-level administrators are studied even less. This research study focuses on the experiences of African-American women administrators (Program Directors and Deans) in higher education institutions, the obstacles they face in pursuit of upward mobility, the support networks they use and strategies they implement. The research study methodology consisted of a mixed-methods approach for the gathering of data. The first method, qualitative, was implemented through conducting in-depth interviews with a small sample (7) of African-American women administrators from varying types of higher education institutions in the northeast region. The second method, quantitative, consisted of administering a survey questionnaire to a larger sample (101) of African-American mid-level women administrators in higher education institutions in the northeast region. From this, a total of 93 usable surveys were returned. From the qualitative and quantitative research data the researcher identified eight common themes. These themes are: institutional climate and culture; barriers faced, supports used; coping and advancement strategies; skills needed; racism and sexism; how African-American women are perceived; and mentoring. Each theme is supported with quotes from the qualitative data and number and frequencies of responses provided from the quantitative data. These themes serve as a framework for discussing the policy and practice implications of the data for institutions of higher education. Implications for the African-American female administrator are addressed also. Lastly, recommendations for future research are provided

Links between biodiversity and human infectious and non-communicable diseases: a review

INTRODUCTION: Biodiversity has intrinsic value and a fundamental role in human health. The relationship between them is complex, and the specific sustaining processes are still not well understood. In view of the rapidly evolving landscape, this literature review investigated scientific evidence for specific links between biodiversity and human infectious and non-communicable diseases to characterise identifiable relationships. METHODS: A search of the PubMed and Web of Science databases using keyword algorithms identified relevant manuscripts published between 1 January 2000 and 18 April 2019. Qualitative data were extracted from 155 studies investigating links between or mechanisms linking biodiversity and infectious disease, non-communicable disease, allergic/inflammatory disease and microbiomes. RESULTS: None of the reviewed studies documented causal evidence for a mechanism linking biodiversity and human health. The main mechanisms proposed to link biodiversity and transmission of infectious disease were dilution and amplification. The dilution hypothesis argues that an increase in species diversity leads to a decrease in pathogen prevalence. The amplification effect is the converse, that there is a positive correlation between species diversity and disease risk/infection prevalence. Several driving factors are postulated, including encounter reduction, interspecies competition and predation. In addition, it appears that scale, both spatial and temporal, highly impacts diversity-disease relationships. There is strong evidence that the early environment of a child, including maternally transferred prenatal signals, affects immune maturation, modifying later disease risk. Bi-directional axes communicate between the gut microbiome and the brain, as well as between the skin microbiome and the lung, leading to direct and indirect immune, humoral and neural mechanisms. The main challenges in assessing links between biodiversity and human health are the wide variation in definitions of health and biodiversity, and the heterogeneity in types of studies encountered, as well as the complexity of interactions in dynamic systems. CONCLUSIONS: Contextually adapted integrative approaches, which maintain dialogue across disciplines and amongst all stakeholders, are most likely to generate robust evidence. Because of the relevance of local scale, research engagement must occur across levels to generate legitimate practices and translate into sustainable, equitable policies. Recommendations for future action include: improve the knowledge base on contribution of biodiversity to health, increase awareness of health effects of natural and near-natural environments and biodiversity, and promote synergies by increasing policy coherence