Description of a turbofan engine product development process

Thesis (S.M.)--Massachusetts Institute of Technology, System Design & Management Program, 2001.Includes bibliographical references (p. 123-125).This research explores what requirements are necessary for the development of a turbofan engine and how they evolve through the product development cycle. This work utilizes a parameter-based design structure matrix (DSM) to define the interfaces and interdependencies present in a large commercial aircraft propulsion system. The DSM was developed from the system level to the module level allowing one to examine the assumptions made throughout the entire life cycle of the product. The work utilizes the system-level DSM to show the similarities between the turbofan engine product development process (PDP) and the software spiral product development process. This work examines the parameter-based DSM in each of the design phases and attempts to understand the assumptions made in each phase and how the assumptions change as the product proceeds through the development cycle. By examination of the DSM, it was found that program goals and requirements lead to an initial set of design parameters. These design parameters are then iterated until a satisfactory product defamation is developed. Each stage concludes with the integration and testing of that stages work. In all stages risk management occurs and with the necessary revision of the program plan for subsequent stages (not in the system-level DSM). The work shows that the PDP for a turbofan engine can be viewed as a spiral process. The thesis then suggests that, in general, the current industry practices for the development of complex physical systems have similarity to the spiral framework for development of software.by Douglas C. Hague.S.M

Measured temporal and spectral PMD characteristics and their implications for network-level mitigation approaches

©2003 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.Signal degradation due to polarization-mode dispersion (PMD) effects may become significant for signaling rates of 10 Gb/s, 40 Gb/s, and beyond. To assess the utility of various PMD mitigation schemes, temporal and spectral measurements of differential group delay (DGD) were made on 95 km of buried standard single-mode fiber over an 86-d period to determine the distribution and rate of change of high-DGD events. As expected, statistical analysis of variations in DGD indicate that excursions from the mean DGD by factors of 3.7 or higher have very low probability. For this link, the DGD varied slowly with time (having a drift time of about 3.4 d) and rapidly with wavelength. The DGD data agree well with results of similar experiments reported in the literature. Statistical analysis of the measured DGD data shows that high-DGD episodes will be exceedingly rare and short-lived. The impact of PMD on network operations is explored and approaches to ensure network reliability are reviewed for network operators given the task of transporting high-bit-rate channels over fiber links with known PMD characteristics

Recommended Personal Protective Equipment for Cochlear Implant and Other Mastoid Surgery During the COVID-19 Era

© 2020 American Laryngological, Rhinological and Otological Society Inc, "The Triological Society" and American Laryngological Association (ALA) Objectives/Hypothesis: The overall aim of this study was to evaluate personal protective equipment (PPE) that may facilitate the safe recommencement of cochlear implantation in the COVID-19 era, with the broader goal of minimizing the period of auditory deprivation in prelingually deaf children and reducing the risk of cochlear ossification in individuals following meningitis. Methods: The study design comprised 1) an objective assessment of mastoid drilling-induced droplet spread conducted during simulated cochlear implant (CI) surgery and its mitigation via the use of a protective drape tent and 2) an evaluation of three PPE configurations by otologists while performing mastoid drilling on ex vivo temporal bones. The various PPE solutions were assessed in terms of their impact on communication, vital physiological parameters, visual acuity and fields, and acceptability to surgeons using a systematic risk-based approach. Results: Droplet spread during simulated CI surgery extended over 2 m, a distance greater than previously reported. A drape tent significantly reduced droplet spread. The ensemble of a half-face mask and safety spoggles (foam lined safety goggles) had consistently superior performance across all aspects of clinical usability. All other PPE options were found to substantially restrict the visual field, making them unsafe for microsurgery. Conclusions: The results of this preclinical study indicate that the most viable solution to enable the safe conduct of CI and other mastoid surgery is a combination of a filtering facepiece (FFP)3 mask or half-face respirator with safety spoggles as PPE. Prescription spoggles are an option for surgeons who need to wear corrective glasses to operate. A drape tent reduces droplet spread. A multicenter clinical trial to evaluate the effectiveness of PPE should be the next step toward safely performing CI surgery during the COVID-19 era. Level of Evidence: 4 Laryngoscope, 2020

Elastic Positron-Proton Scattering at Low Q2^2

Systematic differences in the the proton's charge radius, as determined by ordinary atoms and muonic atoms, have caused a resurgence of interest in elastic lepton scattering measurements. The proton's charge radius, defined as the slope of the charge form factor at Q$^2$=0, does not depend on the probe. Any difference in the apparent size of the proton, when determined from ordinary versus muonic hydrogen, could point to new physics or need for the higher order corrections. While recent measurements seem to now be in agreement, there is to date no high precision elastic scattering data with both electrons and positrons. A high precision proton radius measurement could be performed in Hall B at Jefferson Lab with a positron beam and the calorimeter based setup of the PRad experiment. This measurement could also be extended to deuterons where a similar discrepancy has been observed between the muonic and electronic determination of deuteron charge radius. A new, high precision measurement with positrons, when viewed alongside electron scattering measurements and the forthcoming MUSE muon scattering measurement, could help provide new insights into the origins of the proton radius puzzle, and also provide new experimental constraints on radiative correction calculations.Comment: 9 pages, 8 figures. arXiv admin note: substantial text overlap with arXiv:2007.1508

Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene

We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep-sea drill sites to evaluate the role of Southern Ocean circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (Nd(t) = −9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern-day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (εNd(t) = −8.7 ± 1.5). Antarctic-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by ~2 εNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene

Social Work with Children Affected by Domestic Violence: An Analysis of Policy and Practice Implications

The past decade has seen an increasing awareness of the emotional harm to children that can ensue from exposure to domestic violence. This article develops a framework for understanding social work responses, using an analysis of recent developments in British policy as an example. It is argued that to understand what these developments mean in practice we need to develop our analysis of the value perspectives underpinning them. Issues facing those charged with implementing these sometimes ambiguous policy and practice changes are discussed in three levels of intervention: the macro, the intermediate, and the 'street-level.' The article concludes by calling for closer collaboration between policy makers, practitioners and service users in the co-production of policy

The gender specific frequency of risk factor and CHD diagnoses prior to incident MI: A community study

BACKGROUND: CHD is a chronic disease often present years prior to incident AMI. Earlier recognition of CHD may be associated with higher levels of recognition and treatment of CHD risk factors that may delay incident AMI. To assess timing of CHD and CHD risk factor diagnoses prior to incident AMI. METHODS: This is a 10-year population based medical record review study that included all medical care providers in Olmsted County, Minnesota for all women and a sample of men residing in Olmsted County, MN with confirmed incident AMI between 1995 and 2000. RESULTS: All medical care for the 10 years prior to incident AMI was reviewed for 150 women and 148 men (38% sample) in Olmsted County, MN. On average, women were older than men at the time of incident AMI (74.7 versus 65.9 years, p < 0.0001). 30.4% of the men and 52.0% of the women received diagnoses of CHD prior to incident AMI (p = 0.0002). Unrecognized and untreated CHD risk factors were present in both men (45% of men 5 years prior to AMI) and women (22% of women 5 years prior to first AMI), more common in men and those without a diagnosis of CHD prior to incident AMI (p < 0.0001). CONCLUSION: A CHD diagnosis prior to incident AMI is associated with higher rates of recognition and treatment of CHD risk factors suggesting that diagnosing CHD prior to AMI enhances opportunities to lower the risk of future CHD events

Positioning the principles of precision medicine in care pathways for allergic rhinitis and chronic rhinosinusitis - A EUFOREA-ARIA-EPOS-AIRWAYS ICP statement.

Precision medicine (PM) is increasingly recognized as the way forward for optimizing patient care. Introduced in the field of oncology, it is now considered of major interest in other medical domains like allergy and chronic airway diseases, which face an urgent need to improve the level of disease control, enhance patient satisfaction and increase effectiveness of preventive interventions. The combination of personalized care, prediction of treatment success, prevention of disease and patient participation in the elaboration of the treatment plan is expected to substantially improve the therapeutic approach for individuals suffering from chronic disabling conditions. Given the emerging data on the impact of patient stratification on treatment outcomes, European and American regulatory bodies support the principles of PM and its potential advantage over current treatment strategies. The aim of the current document was to propose a consensus on the position and gradual implementation of the principles of PM within existing adult treatment algorithms for allergic rhinitis (AR) and chronic rhinosinusitis (CRS). At the time of diagnosis, prediction of success of the initiated treatment and patient participation in the decision of the treatment plan can be implemented. The second-level approach ideally involves strategies to prevent progression of disease, in addition to prediction of success of therapy, and patient participation in the long-term therapeutic strategy. Endotype-driven treatment is part of a personalized approach and should be positioned at the tertiary level of care, given the efforts needed for its implementation and the high cost of molecular diagnosis and biological treatment

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference