663 research outputs found

    Implementation of functional build in the vehicle development and launch process

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    Thesis (M.B.A.)--Massachusetts Institute of Technology, Sloan School of Management; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; in conjunction with the Leaders for Manufacturing Program at MIT, 2004.Includes bibliographical references.Prior to production of an automotive assembly, the individually fabricated components must be validated or "tuned in" in order to produce an acceptable assembly. This validation or tune in process must be done before the product can be sold, and is generally a major step in the launch process. Mean shifts and variance within normal production processes result in differences between design intent (specifications) and actual parts. These differences are unavoidable in most processes. During launch processes manufacturers must have strategies for dealing with these differences. One traditional strategy to product launch processes is build-to-print methodology. The basic assumption of this methodology is that by working to make individual parts as close as possible to specification, the assemblies of these parts will also be to specification. In others words one can achieve an optimized assembly by focusing on the individual parts. An alternate methodology to build to print is functional build. A functional build methodology involves focusing on the completed assembly rather than the individual parts. The basic idea is to examine if the overall assembly meets customer requirements. If it does not then the launch team can analyze the individual parts to determine the best way to solve the problem. This solution may or may not involve forcing a part to design intent. In the recent past a major American auto manufacturer has used functional build methodology in the tune-in of the body structures. This auto manufacturer is currently implementing a change to vehicle development process called the craftsmanship initiative. A major part of the craftsmanship initiative involves extending the functional build methodology to a higher level of assembly.(cont.) Functional builds will be extended to include not only body structures but also interior and exterior parts typically installed on a typical vehicle assembly line. This thesis will first examine both the technical and corporate reasoning behind this fundamental change to one of the core processes within the auto manufacturer. Second the thesis will study the underlying challenges surrounding implementation of this change and recommend possible solutions to some of these challenges. The major focus of the internship has been participation on the pilot program that is implementing this change. There are three main areas of difficulty facing the pilot program. These are process design issues, organization structure challenges, and development of appropriate metrics to measure the impact of the change.by Peter T. Haughton.S.M.M.B.A

    The Informal Sector In Francophone Africa: Firm Size, Productivity, And Institutions

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    This book is a major step towards improving the understanding of the complex reality of informal sector firms in francophone West Africa. It innovates by concentrating on informal firms rather than informal employment (as other studies do), and identifying \u27large informal\u27 sector firms whose sales rival those of large formal-sector firms but operate in ways that are similar to small informal operators. Not only is the regulatory environment facing these two types of informal firms distinct, but policies aimed at improving their productivity need to be differentiated. This study focuses on the urban informal sector in three capital cities: Dakar (Senegal), Cotonou (Benin), and Ouagadougou (Burkina Faso). The study also breaks new ground with an eclectic methodology and primary data collection. Quantitative and qualitative firm-level data were collected involving a unique and fruitful collaboration among academic researchers, government officials, the West African economic and monetary union commission, informal and formal sector business associations, and labor unions. This volume represents the culmination of a long collaboration between the Centre de Recherches Economiques Appliquees (CREA) at the University Cheikh Anta Diop of Dakar and the World Bank

    Flight performance of actively foraging honey bees is reduced by a common pathogen

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    ArticleSudden and severe declines in honey bee (Apis mellifera) colony health in the US and Europe have been attributed, in part, to emergent microbial pathogens, however, the mechanisms behind the impact are unclear. Using roundabout flight mills, we measured the flight distance and duration of actively foraging, healthy-looking honey bees sampled from standard colonies, before quantifying the level of infection by Nosema ceranae and Deformed Wing Virus complex (DWV) for each bee. Neither the presence nor quantity of N. ceranae at low, natural levels of infection had any effect on flight distance or duration, but presence of DWV reduced flight distance by two thirds and duration by one half. Quantity of DWV was shown to have a significant, but weakly positive relation with flight distance and duration, however, the low amount of variation that was accounted for suggests further investigation by dose-response assays is required. We conclude that widespread, naturally occurring levels of infection by DWV weaken the flight ability of honey bees and high levels of within-colony prevalence are likely to reduce efficiency and increase the cost of resource acquisition. Predictions of implications of pathogens on colony health and function should take account of sub-lethal effects on flight performance.This work was funded by the Insect Pollinators Initiative (IPI) grants BB/I000100/1, BB/I000097/1 and BB/I000097/2, C.B. Dennis British Beekeepers' Research Trust and the High Wycombe Beekeepers’ Association. The IPI is funded jointly by the BBSRC, Defra, NERC, The Scottish Government and The Wellcome Trust, under the LWEC Partnership. Rothamsted Research is a national institute of bioscience strategically funded by the BBSRC

    Options and Strategies for Balanced Development for Liveable Cities: An Epilogue

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    This chapter provides a snapshot of what is covered in the preceding chapters on options and strategies for balanced development leading to liveable cities. The chapters are organized under nine sections, including peri-urbanization; culture and social economy; land use planning; water security; wastewater and irrigation; urban agriculture and food security; impact of climate change and adaptation; legal, policy and institutional framework; and integrated urban development. The chapters under these sections cover a broad range of issues for the planning of future cities and peri-urban regions with respect to (1) balanced urban development policies and institutions for future cities; (2) understanding the effects of land use change, population increase, and water demand for the liveability of cities; (3) long-term planning needs and transboundary approaches to ensure secured future for generations ahead; and (4) strategies for optimal land, water, and energy uses for viable and liveable cities. The book emphasizes integrated planning for future development of liveable, resilient, and sustainable cities and peri-urban areas

    Interpreting syndepositional sediment remobilization and deformation beneath submarine gravity flows; a kinematic boundary layer approach

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    Turbidite sandstones and related deposits commonly contain deformation structures and remobilized sediment that might have resulted from post-depositional modification such as downslope creep (e.g. slumping) or density-driven loading by overlying deposits. However, we consider that deformation can occur during the passage of turbidity currents that exerted shear stress on their substrates (whether entirely pre-existing strata, sediment deposited by earlier parts of the flow itself or some combination of these). Criteria are outlined here, to avoid confusion with products of other mechanisms (e.g. slumping or later tectonics), which establish the synchronicity between the passage of overriding flows and deformation of their substrates. This underpins a new analytical framework for tracking the relationship between deformation, deposition and the transit of the causal turbidity current, through the concept of kinematic boundary layers. Case study examples are drawn from outcrop (Miocene of New Zealand, and Apennines of Italy) and subsurface examples (Britannia Sandstone, Cretaceous, UK Continental Shelf). Example structures include asymmetric flame structures, convolute lamination, some debritic units and injection complexes, together with slurry and mixed slurry facies. These structures may provide insight into the rheology and dynamics of submarine flows and their substrates, and have implications for the development of subsurface turbidite reservoirs

    Telomere-based proliferative lifespan barriers in Werner-syndrome fibroblasts involve both p53-dependent and p53-independent mechanisms

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    Werner-syndrome fibroblasts have a reduced in vitro life span before entering replicative senescence. Although this has been thought to be causal in the accelerated ageing of this disease, controversy remains as to whether Werner syndrome is showing the acceleration of a normal cellular ageing mechanism or the occurrence of a novel Werner-syndrome-specific process. Here, we analyse the signalling pathways responsible for senescence in Werner-syndrome fibroblasts. Cultured Werner-syndrome (AG05229) fibroblasts senesced after approximately 20 population doublings with most of the cells having a 2N content of DNA. This was associated with hypophosphorylated pRb and high levels of p16(Ink4a) and p21(Waf1). Senescent AG05229 cells re-entered the cell cycle following microinjection of a p53-neutralizing antibody. Similarly, production of the human papilloma virus 16 E6 oncoprotein in presenescent AG05229 cells resulted in senescence being bypassed and extended cellular life span. Werner-syndrome fibroblasts expressing E6 did not proliferate indefinitely but reached a second proliferative lifespan barrier, termed M(int), that could be bypassed by forced production of telomerase in post-M1 E6-producing cells. The conclusions from these studies are that: (1) replicative senescence in Werner-syndrome fibroblasts is a telomere-induced p53-dependent event; and (2) the intermediate lifespan barrier M(int) is also a telomere-induced event, although it appears to be independent of p53. Werner-syndrome fibroblasts resemble normal human fibroblasts for both these proliferative lifespan barriers, with the strong similarity between the signalling pathway linking telomeres to cell-cycle arrest in Werner-syndrome and normal fibroblasts providing further support for the defect in Werner syndrome causing the acceleration of a normal ageing mechanism

    Flight performance of actively foraging honey bees is reduced by a common pathogen

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    Sudden and severe declines in honey bee (Apis mellifera) colony health in the US and Europe have been attributed, in part, to emergent microbial pathogens, however, the mechanisms behind the impact are unclear. Using roundabout flight mills, we measured the flight distance and duration of actively foraging, healthy‐looking honey bees sampled from standard colonies, before quantifying the level of infection by Nosema ceranae and Deformed Wing Virus complex (DWV) for each bee. Neither the presence nor the quantity of N. ceranae were at low, natural levels of infection had any effect on flight distance or duration, but presence of DWV reduced flight distance by two thirds and duration by one half. Quantity of DWV was shown to have a significant, but weakly positive relation with flight distance and duration, however, the low amount of variation that was accounted for suggests further investigation by dose‐response assays is required. We conclude that widespread, naturally occurring levels of infection by DWV weaken the flight ability of honey bees and high levels of within‐colony prevalence are likely to reduce efficiency and increase the cost of resource acquisition. Predictions of implications of pathogens on colony health and function should take account of sublethal effects on flight performance

    A monoclonal antibody to the insect prothoracicotropic hormone

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    The prothoracicotropic hormone (PTTH) is an insect cerebral peptide that stimulates the prothoracic glands to produce the steroid hormone ecdysone thus initiating molting and metamorphosis. "Big" PTTH, one of several molecular forms of the neurohormone, was isolated from brains of the tobacco hornworm Manduca sexta, and fractionated by high-pressure liquid chromatography (HPLC) for use in antibody production. A murine polyclonal antiserum and a monoclonal antibody (MAb) have been generated using this highly purified preparation of big PTTH. Antisera and hybridoma supernatants were screened with an indirect, brain whole-mount immunocytological assay, and antibody specificity was confirmed by immunocytological, ELISA, and functional criteria. In brain whole-mount preparations, the MAb (A2H5) and antiserum specifically immunostained the lateral protocerebral neurosecretory cells (L-NSC III), the prothoracicotropes, which produce PTTH. This immunostaining was blocked by preadsorbing the antibodies with big PTTH. Analysis of the elution of HPLC-fractionated big PTTH with an in vitro bioassay for the neurohormone and an ELISA employing the A2H5 MAb resulted in peaks of activity that were superimposable. Finally, the antiserum and A2H5 MAb inhibited big PTTH activation of the prothoracic glands to synthesize ecdysone in the in vitro bioassay for the neurohormone. With these specific antibodies, the organization of the PTTH neuroendocrine axis has been defined. It is now evident that both of the peptidergic neurons that comprise the L-NSC III are prothoracicotropes, and that the corpora allata are the neurohemal organs for the release of big PTTH into the hemolymph. This study indicates that these specific antibodies will be useful in investigations of numerous aspects of the biology of this cerebral neuroendocrine axis
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