1,141 research outputs found

    Arrow-wing supersonic cruise aircraft structural design concepts evaluation. Volume 4: Sections 15 through 21

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    The analyses performed to provide structural mass estimates for the arrow wing supersonic cruise aircraft are presented. To realize the full potential for structural mass reduction, a spectrum of approaches for the wing and fuselage primary structure design were investigated. The objective was: (1) to assess the relative merits of various structural arrangements, concepts, and materials; (2) to select the structural approach best suited for the Mach 2.7 environment; and (3) to provide construction details and structural mass estimates based on in-depth structural design studies. Production costs, propulsion-airframe integration, and advanced technology assessment are included

    Virtual simulation of the postsurgical cosmetic outcome in patients with pectus excavatum

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    Pectus excavatum is the most common congenital deformity of the anterior chest wall, in which several ribs and the sternum grow abnormally. Nowadays, the surgical correction is carried out in children and adults through Nuss technic. This technic has been shown to be safe with major drivers as cosmesis and the prevention of psychological problems and social stress. Nowadays, no application is known to predict the cosmetic outcome of the pectus excavatum surgical correction. Such tool could be used to help the surgeon and the patient in the moment of deciding the need for surgery correction. This work is a first step to predict postsurgical outcome in pectus excavatum surgery correction. Facing this goal, it was firstly determined a point cloud of the skin surface along the thoracic wall using Computed Tomography (before surgical correction) and the Polhemus FastSCAN (after the surgical correction). Then, a surface mesh was reconstructed from the two point clouds using a Radial Basis Function algorithm for further affine registration between the meshes. After registration, one studied the surgical correction influence area (SCIA) of the thoracic wall. This SCIA was used to train, test and validate artificial neural networks in order to predict the surgical outcome of pectus excavatum correction and to determine the degree of convergence of SCIA in different patients. Often, ANN did not converge to a satisfactory solution (each patient had its own deformity characteristics), thus invalidating the creation of a mathematical model capable of estimating, with satisfactory results, the postsurgical outcome.Fundação para a Ciência e a Tecnologia, Portugal (FCT) through the Postdoc grant referenced SFRH/BPD/46851/2008 and R&D project referenced PTDC/SAU-BEB/103368/2008

    Automated feature recognition system for supporting engineering activities downstream of conceptual design.

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    Transfer of information between CAD models and downstream manufacturing process planning software typically involves redundant user interaction. Many existing tools are process-centric and unsuited for selection of a "best process" in the context of existing concurrent engineering design tools. A computer based Feature-Recognition (FR) process is developed to extract critical manufacturing features from engineering product CAD models. FR technology is used for automating the extraction of data from CAD product models and uses wire-frame geometry extracted from an IGES neutral file format. Existing hint-based feature recognition techniques have been extended to encompass a broader range of manufacturing domains than typical in the literature, by utilizing a combination of algorithms, each successful at a limited range of features. Use of wire-frame models simplifies product geometry and has the potential to support rapid manufacturing shape evaluation at the conceptual design stage. Native CAD files are converted to IGES neutral files to provide geometry data marshalling to remove variations in user modelling practice, and to provide a consistent starting point for FR operations. Wire-frame models are investigated to reduce computer resources compared to surface and solid models, and provide a means to recover intellectual property in terms of manufacturing design intent from legacy and contemporary product models. Geometric ambiguity in regard to what is ?solid? and what is not has plagued wire-frame FR development in the past. A new application of crossing number theory (CNT) has been developed to solve the wire-frame ambiguity problem for a range of test parts. The CNT approach works satisfactorily for products where all faces of the product can be recovered and is tested using a variety of mechanical engineering parts. Platform independent tools like Extensible Mark-up Language are used to capture data from the FR application and provide a means to separate FR and decision support applications. Separate applications are composed of reusable software modules that may be combined as required. Combining rule-based and case-based reasoning provides decision support to the manufacturing application as a means of rejecting unsuitable processes on functional and economic grounds while retaining verifiable decision pathways to satisfy industry regulators

    Long View (41RB112): Data Recovery of Two Plains Village Period Components in Roberts County, Texas, Volume 2

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    This archeological data recovery investigation in Roberts County in the northeastern panhandle of Texas was necessitated by the proposed widening of State Highway 70 (CSJ: 0490-04-037) by the Texas Department of Transportation (TxDOT), Amarillo District. This proposed highway rehabilitation program will directly impact a roughly 10 meter (m, 30 ft.) wide north-south section of prehistoric site 41RB112, the Long View site. This site consists of two horizontally distinct Plains Village period occupations shallowly buried along a linear interfluvial ridge between two small tributary creeks to the Canadian River in the midslope of this broad, dissected valley. This site was initially discovered by TxDOT archeologist, Dennis Price in June 2004 during an archeological inventory of the proposed 9.7 kilometer (6 mile) section north of the Canadian River in response to the planned highway rehabilitation program. Based on Mr. Price’s discovery of multiple artifact classes in buried context he recommended this site be assessed for its eligibility for listing on the National Register of Historic Places under criterion d and possible designation as a State Archeological Landmark (SAL) per the requirements of Section 106 of the National Historic Preservation Act (NHPA) and other related legislation. Following the Texas Historical Commissions concurrence with that recommendation, TxDOT through the Environmental (ENV) Affairs Division, contracted to TRC Environmental Corporation (TRC) under an existing Scientific Services Contract No. 57XXSA006 and issued a Work Authorization to TRC of Austin to conduct the site eligibility assessment. During a site visit by TxDOT geoarcheologist James Abbott and TRC archeologist Mike Quigg in February 2005, the site boundaries were expanded to nearly 300 meters (m) along the proposed area of potential effect (APE). Investigative strategies were devised to assess the Long View site. In May 2005, TRC’s archeologists from Austin conducted archeological testing for a NRHP and SAL eligibility assessment investigation at 41RB112. The assessment along the 10-m-wide by 300-m-long APE was accomplished by hand-excavating 28 1-by-1 m units (totaling 16.8 m3), hand-excavating four narrow ca. 30 centimeter (cm) wide trenches (two in each area totaling nearly 32 linear meters), as well as cleaning and inspecting 28 m of existing road cut exposures. These investigations determined that cultural materials clustered at the northern and southern ends (Areas A and C respectively) of the site with nearly 120 m of noncultural bearing deposits (Area B) between the two concentrations. A 4-m-wide mechanically bladed fireguard paralleled the existing fenceline throughout the length of the APE and disturbed much of the near surface materials in that zone. The opposite, eastern side of the highway was investigated through the excavation of six 50-by-50 cm shovel tests, surface, and road cut inspection. Based on the results from the hand-excavations and various collections conducted during the site assessment, it became apparent that the two ends (Areas A and C) of the Long View site in TxDOT’s proposed APE contained well-defined cultural components in the top 50 cmbs. Each end appeared to represent habitation remains from single occupation episodes with potential structures, restricted to a narrow time period of less than 100 years between uncalibrated 630 and 710 B.P. of the Plains Village period. Rodent and natural disturbances had vertically displaced some small cultural objects within the sandy deposits, but the restricted period of occupation to roughly a 100 year period reduces this impact. TRC recommended the site was eligible for listing on the National Register and as a State Landmark. The Texas Historical Commissions concurred with that recommendation, and subsequently the ENV Affairs Division of TxDOT, again contracted to TRC under an existing Scientific Services Contract No. 575XXSA008 and issued a Work Authorization to TRC Austin to perform the mitigation of the proposed impacts. Data recovery investigations were conducted during August through November 2006 along the western side of the existing highway. The previously identified northern-Area A and southern–Area C areas with high concentrations of cultural materials were targeted. These investigations began with a thorough geophysical survey that employed three noninvasive electrical detective instruments across Areas A and C anticipating to detect the locations of subsurface cultural features to target by hand-excavations. Some excavations targeted the detected anomalies, whereas others targeted previously identified features. In the end, hand-excavated blocks were completed in Areas A and C. The excavations totaled 128 m2 in Area A and 93 m2 in Area C for a grand total of 221 m2 or 103.4 m3. In conjunction with the archeological excavations, geoarcheological investigations focused on defining the age and development of the natural Holocene sediments that contained the cultural materials. The geoarcheological assessment included detailed stratigraphic documentation of site and near site deposits, sediment texture characterization, soil thin sections, magnetic susceptibility, multiple chemical analyses (organic, calcium, and phosphorus). Detailed stratigraphic data was also collected at two rare pithouse structures to pursue construction and filling episodes. The excavations yielded significant and diverse cultural assemblages from the two occupations assigned Component A and C. Both components are attributed to the Plains Village period with two discrete occupations dating to uncalibrated 460 to 535 B.P. (cal A.D. 1398 to 1447) in Component A and 530 to 700 B.P. (cal A.D. 1280 to 1437) in Component C. The two assemblages are significant not only in their diversity and quality of materials but also in the information they yielded. This report represents one of the first complete documents to present the entire cultural assemblage from a single site for this time period and region. The total recovered assemblage includes 157 formal chipped and ground stone tools, 226 informal tools, 3,414 pieces of lithic debitage, over 6,400 faunal fragments (1.4 kg), some 1,541 ceramic sherds, 1,790 burned rocks, at least 116 macrobotanical samples that includes 16 maize cobs, two human burials, and remains of a third, juvenile scattered along a previously bladed fireguard, 32 intact cultural features that include two rare pithouses, and other cultural debris related to these two campsites. The human remains and associated artifacts will be repatriated in accord with the requirements of the Native American Graves Protection and Repatriation Act (NAGPRA). A suite of 10 technical analyses directed at mostly the cultural assemblages included; use-wear, phytolith, diatom, petrography, macrobotanical, starch grain, instrumental neutron activation, bison bone isotopes, obsidian sourcing, radiocarbon and optical stimulated dating. This data was used to address 11 specific research questions concerning these Plains Village period occupations. Not only does the cultural debris contribute to our understanding of the time period but the geoarcheological information obtained explains the conditions and how the materials were preserved, and inform us concerning the past depositional environment in this immediate area. The combined information contributes to a significant understanding to a specific part of the Plains Village cultures in the Texas panhandle. Following the acceptance of the final report by the TxDOT and the Texas Historical Commission these cultural materials and all the documentation from the combined investigations will be permanently curated at Texas State University in San Marcos, Texas. The curated materials will provide important data that can be researched by interested parties in the future

    Failure characteristics of all polyethylene cemented glenoid implants in total shoulder arthroplasty

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    Total shoulder arthroplasty (TSA) still suffers today from mid-term and long-term complications such as glenoid implant loosening, wear, humeral head subluxation/dislocation and implant fracture. Unlike the hip and knee joint replacements, the artificial shoulder joint has yet to offer a long-term satisfactory solution to shoulder replacement. With loosening being the number one reason for TSA revision, investigating methods of monitoring the glenoid implant loosening and investigate the effects of various design parameters on the loosening behaviour of the glenoid fixation is necessary to explore the problem. Several studies were carried out using in-vitro cyclic testing and FEA to; investigate failure progression and its correlation to quantitative measures in a 2D study (n = 60), investigating key glenoid design features in a 2D (n = 60) and 3D study (n = 20), investigating the validity of using bone substitute foam for studying glenoid fixation in a cadaveric study and investigating any correlation between failure and CT or in-vitro quantitative measures (n = 10). Visible failure was observed, for the first time, correlating to inferior rim displacement and vertical head displacement measures. CT failure was detected in 70% of specimens before visible failure was observed. Out of the design pairs tested; smooth-back/rough-back (range of roughnesses), peg/keel, curved-back/flat-back and conforming/non-conforming, roughening the back-surface to 3.4 μm or more improved fixation performance (p < 0.05). Roughening the back-surface changed the mode of failure from implant/cement failure inferiorly due to tensile/shear stresses, to cement/bone failure superiorly due to compressive/shear loading. Differences in the other design pairs were marked showing peg to perform better than keel, conforming over non-conforming and no difference in curved-back over flat-back, although these differences are marginal. Improvements in the standard testing method have also been suggested

    Proceedings of the 11th international conference on NDE in relation to structural integrity for nuclear and pressurized components

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    This Conference, the eleventh in a series on NDE in relation to structural integrity for nuclear and pressurized components, was held in Jeju Island, Korea, from 19th to 21st of May 2015. The scientific programme was co-produced by the European Commission’s Joint Research Centre, Institute for Energy and Transport (EC-JRC/IET). Previous conferences were held in Amsterdam in October 1998, New Orleans in May 2000, Seville in November 2001, London in December 2004, San Diego in May 2006, Budapest in October 2007, Yokohama in May 2009, Berlin in September 2010, Seattle in May 2012, and Cannes in October 2013. All were highly successful in the quality and scope of the technical programs and the number of attendees from all countries with an interest in the structural integrity of nuclear and pressurized components. The overall objectives of the Conference were to provide an up-to-date assessment of the development and application of NDE and to allow technical interchange between experts on an international basis. The Conference covered all aspects of this extremely important subject, with special regard to the links between structural integrity requirements and NDE performance. The development of improved NDE systems and methods was highlighted. Determination of NDE performance by development of qualification systems or performance demonstration, and experience of their use in practice was prominently featured.JRC.F.5-Nuclear Reactor Safety Assessmen

    Change blindness: eradication of gestalt strategies

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    Arrays of eight, texture-defined rectangles were used as stimuli in a one-shot change blindness (CB) task where there was a 50% chance that one rectangle would change orientation between two successive presentations separated by an interval. CB was eliminated by cueing the target rectangle in the first stimulus, reduced by cueing in the interval and unaffected by cueing in the second presentation. This supports the idea that a representation was formed that persisted through the interval before being 'overwritten' by the second presentation (Landman et al, 2003 Vision Research 43149–164]. Another possibility is that participants used some kind of grouping or Gestalt strategy. To test this we changed the spatial position of the rectangles in the second presentation by shifting them along imaginary spokes (by ±1 degree) emanating from the central fixation point. There was no significant difference seen in performance between this and the standard task [F(1,4)=2.565, p=0.185]. This may suggest two things: (i) Gestalt grouping is not used as a strategy in these tasks, and (ii) it gives further weight to the argument that objects may be stored and retrieved from a pre-attentional store during this task

    Proceedings of the 11th international conference on NDE in relation to structural integrity for nuclear and pressurized components

    Get PDF
    This Conference, the eleventh in a series on NDE in relation to structural integrity for nuclear and pressurized components, was held in Jeju Island, Korea, from 19th to 21st of May 2015. The scientific programme was co-produced by the European Commission’s Joint Research Centre, Institute for Energy and Transport (EC-JRC/IET). Previous conferences were held in Amsterdam in October 1998, New Orleans in May 2000, Seville in November 2001, London in December 2004, San Diego in May 2006, Budapest in October 2007, Yokohama in May 2009, Berlin in September 2010, Seattle in May 2012, and Cannes in October 2013. All were highly successful in the quality and scope of the technical programs and the number of attendees from all countries with an interest in the structural integrity of nuclear and pressurized components. The overall objectives of the Conference were to provide an up-to-date assessment of the development and application of NDE and to allow technical interchange between experts on an international basis. The Conference covered all aspects of this extremely important subject, with special regard to the links between structural integrity requirements and NDE performance. The development of improved NDE systems and methods was highlighted. Determination of NDE performance by development of qualification systems or performance demonstration, and experience of their use in practice was prominently featured.JRC.F.5-Nuclear Reactor Safety Assessmen

    International Conference on Continuous Optimization (ICCOPT) 2019 Conference Book

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    The Sixth International Conference on Continuous Optimization took place on the campus of the Technical University of Berlin, August 3-8, 2019. The ICCOPT is a flagship conference of the Mathematical Optimization Society (MOS), organized every three years. ICCOPT 2019 was hosted by the Weierstrass Institute for Applied Analysis and Stochastics (WIAS) Berlin. It included a Summer School and a Conference with a series of plenary and semi-plenary talks, organized and contributed sessions, and poster sessions. This book comprises the full conference program. It contains, in particular, the scientific program in survey style as well as with all details, and information on the social program, the venue, special meetings, and more

    Mathematical Foundations of Machine Learning (hybrid meeting)

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    Machine learning has achieved remarkable successes in various applications, but there is wide agreement that a mathematical theory for deep learning is missing. Recently, some first mathematical results have been derived in different areas such as mathematical statistics and statistical learning. Any mathematical theory of machine learning will have to combine tools from different fields such as nonparametric statistics, high-dimensional statistics, empirical process theory and approximation theory. The main objective of the workshop was to bring together leading researchers contributing to the mathematics of machine learning. A focus of the workshop was on theory for deep neural networks. Mathematically speaking, neural networks define function classes with a rich mathematical structure that are extremely difficult to analyze because of non-linearity in the parameters. Until very recently, most existing theoretical results could not cope with many of the distinctive characteristics of deep networks such as multiple hidden layers or the ReLU activation function. Other topics of the workshop are procedures for quantifying the uncertainty of machine learning methods and the mathematics of data privacy
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