Articles de revues sur le sujet « Geometrical variability management »
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Vasconcellos Real, Mauro de, Américo Campos Filho et Sérgio Roberto Maestrini. « Response variability in reinforced concrete structures with uncertain geometrical and material properties ». Nuclear Engineering and Design 226, no 3 (décembre 2003) : 205–20. http://dx.doi.org/10.1016/s0029-5493(03)00110-9.
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Parasonis, Josifas. « POSSIBILITIES OF OPERATIONAL USE OF RELIABILITY THEORY METHODS/PATIKIMUMO TEORIJOS METODŲ PRAKTINIO TAIKYMO GALIMYBĖS ». JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 7, no 5 (31 octobre 2001) : 339–44. http://dx.doi.org/10.3846/13921525.2001.10531751.
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The possibilities of using methods of a reliability theory are considered from the point of view of solving three problem groups. At first, collecting representative statistical data about loadings, design schemes, physical-mechanical characteristics of materials, geometrical parameters of structures, etc. Secondly, it is necessary to investigate reliability of the applied deterministic calculation and to evaluate statistically possible inaccuracies in calculations. At last, rated probabilities of the failure of structures. Use of reliability theory methods can be extended. It is necessary to accumulate statistical data about changes in time of strength and deformation properties of structural materials for reinforced concrete structures, variability of concrete strength in structures. It is necessary to accumulate statistics about actions and to solve the problem of values of factors. It has been marked that the studies of reliability of the design methods are realized for rather simple members subjected to bending and compression without consideration of materials properties in time. The expediency of experimental research on reliability of structures is discussed. Taking into account our experience of influence on reliability of frames of one-storey industrial buildings of the precision of geometrical parameters of mounting, it is expedient study reliability separately from design, mounting and maintenance stages. The new approach to a reliability estimation on the basis of ensuring functional reliablity of buildings is discussed. Thus the probability of failure should be equal to the magnitude of probability.
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Maláková, Silvia, et Samuel Sivák. « GPS Application in the Design of Gearboxes ». Acta Mechanica et Automatica 16, no 4 (14 octobre 2022) : 309–15. http://dx.doi.org/10.2478/ama-2022-0037.
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Abstract The integrated geometrical product specification (GPS) system for workpiece geometry specification and verification is an improved engineering tool for product development and production. The goal of the GPS system is to provide tools for cost-effective management of variability in products and processes. This can be achieved by using a more precise way of expressing the functional requirements of the workpiece, complete and well-defined specifications and integrated verification approaches. The intended function of the product is ensured by controlling the geometry and material properties of the workpiece parts, which make up the product. GPS is a language just for checking geometry, and further development is based on computational mathematics and correct, consistent logic using general sets of rules that can be applied to all types of specifications. This article deals with the application of GPS rules in the design of gearboxes.
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Gonzalez-Artetxe, Asier, José Pino-Ortega, Markel Rico-González et Asier Los Arcos. « Variability of the Motor Behavior during Continued Practice of the Same Motor Game : A Preliminary Study ». Sustainability 12, no 22 (22 novembre 2020) : 9731. http://dx.doi.org/10.3390/su12229731.
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Motor behavior assessment during games could help physical education teachers and team coaches to design effective and efficient motor interventions. This study aimed to assess the variability of the physical and behavioral responses during continued practice of the game tail tag with a ball. Sixteen Spanish youth soccer players from an under-14 team played tail tag, with a ball, during four sessions (5 repetitions of 1 min per session). Physical (i.e., Total Distance (TD) and PlayerLoad (PL)) and behavioral (i.e., Surface Area (SA) and change in the Geometrical Centre position (cGCp)) dimensions were assessed with a local positioning system. The mean of the five series of each session was considered for further statistical analysis. The main finding was that the external load decreased (d = small − large) and the use of space varied during the continued practice of tail tag. Initially, SA increased substantially (d = large) and cGCp decreased slightly (d = small), and then both variables tended to stabilize. This suggests that after several repetitions of the same motor game, physical education teachers and team sports coaches should use this again later, modifying this or proposing new motor games where players respond to these activities that consist in greater uncertainty than to well-known motor games.
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Costa, Francesco, Filippo Boriani, Syed Haroon Ali Shah et Jeyaram Srinivasan. « Parallelogram Excision : An Algorithmic Approach for Excision Designs in High-Tension Skin Areas ». Healthcare 11, no 19 (26 septembre 2023) : 2624. http://dx.doi.org/10.3390/healthcare11192624.
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Introduction: The excision of lesions that are not oriented along the skin tension lines may cause the surgeon to design extremely broad elliptical preoperative markings, with the intent to follow the tension lines as recommended for the best postoperative course and the best quality scars. The aim of this study is to describe and clinically apply a new surgical technique called the parallelogram excision technique, in which the traditional ellipse with a major axis parallel to the tension lines is converted into a parallelogram whose lesser sides are coincident with the local skin tension lines. This technique was specifically conceived for lesions whose major axis is non-coincident with skin tension lines, and the primary advantage is that it reduces the amount of healthy tissue excised. Methods: Preliminarily to this clinical study, a comparative geometrical analysis was conducted between various excision shapes and angles using Geometry Pad version 2.7.10 (Bytes Arithmetic LLC) and verifying the data obtained through AutoCAD 2D 2016 (Autodesk, San Rafael, CA, USA), with the purpose of optimizing the technique from a geometrical point of view. A comparison was performed between the theoretical traditional elliptical excision and the hypothetical parallelogram excision. A pilot proof of concept clinical study was performed to verify the validity of the excisional design proposed. The patients considered for parallelogram excision suffered from skin lesions with a diameter no greater than 4 cm and oriented 45° to 60° with respect to tension lines. In order to limit variability, patients’ ages were between 40 and 80, and the selected areas were limbs, sternum and dorsum. Scar quality was assessed with the validated POSAS method at 6 months post-operation. Results: The geometrical analysis of the parallelogram’s design showed that it allows a diminution of the excised healthy skin compared to the traditional ellipse. The clinical series included 16 patients, with a mean age of 63.5. Of these, nine patients were men and seven were women. Diagnoses included basal cell carcinoma in seven cases, dysplastic naevus in five patients, Bowen’s disease in three individuals, and one case where a wider excision of a malignant melanoma was performed. Six-month follow up results showed: (1) an uneventful postoperative course; (2) good scar healing with an observer’s POSAS median score of 16 and a patient’s POSAS median score of 19; and (3) complete excision of lesions. Conclusions: When indicated, the parallelogram excision technique appears to be a good option for the excision and primary closure of skin lesions that are not parallel to skin tension lines, since it allows a reproducible and surgeon-friendly method of preoperative marking and implies a favorable use of the local tension, which determines good quality scars. The amount of healthy tissue removed is smaller compared to traditional elliptic excisions.
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Schneider-Marin, Patricia, Hannes Harter, Konstantin Tkachuk et Werner Lang. « Uncertainty Analysis of Embedded Energy and Greenhouse Gas Emissions Using BIM in Early Design Stages ». Sustainability 12, no 7 (26 mars 2020) : 2633. http://dx.doi.org/10.3390/su12072633.
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With current efforts to increase energy efficiency and reduce greenhouse gas (GHG) emissions of buildings in the operational phase, the share of embedded energy (EE) and embedded GHG emissions is increasing. In early design stages, chances to influence these factors in a positive way are greatest, but very little and vague information about the future building is available. Therefore, this study introduces a building information modeling (BIM)-based method to analyze the contribution of the main functional parts of buildings to find embedded energy demand and GHG emission reduction potentials. At the same time, a sensitivity analysis shows the variance in results due to the uncertainties inherent in early design to avoid misleadingly precise results. The sensitivity analysis provides guidance to the design team as to where to strategically reduce uncertainties in order to increase precision of the overall results. A case study shows that the variability and sensitivity of the results differ between environmental indicators and construction types (wood or concrete). The case study contribution analysis reveals that the building’s structure is the main contributor of roughly half of total GHG emissions if the main structural material is reinforced concrete. Exchanging reinforced concrete for a wood structure reduces total GHG emissions by 25%, with GHG emissions of the structure contributing 33% and windows 30%. Variability can be reduced systematically by first reducing vagueness in geometrical and technical specifications and subsequently in the amount of interior walls. The study shows how a simplified and fast BIM-based calculation provides valuable guidance in early design stages.
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Udroiu, Razvan, et Ion Cristian Braga. « System Performance and Process Capability in Additive Manufacturing : Quality Control for Polymer Jetting ». Polymers 12, no 6 (4 juin 2020) : 1292. http://dx.doi.org/10.3390/polym12061292.
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Polymer-based additive manufacturing (AM) gathers a great deal of interest with regard to standardization and implementation in mass production. A new methodology for the system and process capabilities analysis in additive manufacturing, using statistical quality tools for production management, is proposed. A large sample of small specimens of circular shape was manufactured of photopolymer resins using polymer jetting (PolyJet) technology. Two critical geometrical features of the specimen were investigated. The variability of the measurement system was determined by Gage repeatability and reproducibility (Gage R&R) methodology. Machine and process capabilities were performed in relation to the defined tolerance limits and the results were analyzed based on the requirements from the statistical process control. The results showed that the EDEN 350 system capability and PolyJet process capability enables obtaining capability indices over 1.67 within the capable tolerance interval of 0.22 mm. Furthermore, PolyJet technology depositing thin layers of resins droplets of 0.016 mm allows for manufacturing in a short time of a high volume of parts for mass production with a tolerance matching the ISO 286 IT9 grade for radial dimension and IT10 grade for linear dimensions on the Z-axis, respectively. Using microscopy analysis some results were explained and validated from the capability study.
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Czerwiński, Grzegorz, et Jerzy Wołoszyn. « Influence of the Longitudinal and Tree-Shaped Fin Parameters on the Shell-and-Tube LHTES Energy Efficiency ». Energies 16, no 1 (26 décembre 2022) : 268. http://dx.doi.org/10.3390/en16010268.
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Changes in the energy sector, associated with the move away from fossil fuels, pose a challenge for appropriate thermal energy management in residential buildings. The important element to deal with the variability of renewable energy in thermal systems is latent heat thermal energy storage. Due to the low thermal conductivity of phase change materials, a number of techniques are proposed to enhance the heat transfer process. In this research, the global sensitivity of fin geometrical parameters on the melting and solidification times and energy efficiency of these processes was investigated. The computational model of the phase change was developed using the finite volume method with the enthalpy-porosity model and Boussinesq approximation. Numerical simulations were carried out according to the design of experiments technique. The multi-dimensional response surface was developed, and the multi-objective optimisation was done. The research shows that the melting process is most influenced by the position of the top fin (α angle) and the solidification process by the position of the bottom fin (γ angle). The angle of the tree fin (β) has a different effect on both processes, with the energy efficiency decreasing during melting and increasing during solidification. Maximum values for the energy efficiencies of melting (ηm=0.973) and solidification (ηs=0.988) were obtained for α=18.2∘, β=89.0∘, L=10.7mm and γ=21.0∘.
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Kala, Zdeněk, Libor Puklický, Abayomi Omishore, Marcela Karmazínová et Jindřich Melcher. « STABILITY PROBLEMS OF STEEL‐CONCRETE MEMBERS COMPOSED OF HIGH‐STRENGTH MATERIALS ». JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 16, no 3 (30 septembre 2010) : 352–62. http://dx.doi.org/10.3846/jcem.2010.40.
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The presented paper deals with the stochastic analysis of the ultimate limit states of steel‐concrete building members. The load carrying capacity of steel‐concrete columns, comprising of steel profiles encased in high strength concrete, in compression is analyzed. The first part of the paper lists assumptions for the determination of the theoretical load carrying capacity of the column. Principles of elasticity and plasticity are used to determine stresses in the concrete and steel sections. Statistical characteristics of input material and geometrical imperfections are listed. Results of the theoretical analysis are then compared with results of experimental research. Statistical characteristics of obtained results of the theoretical analysis were verified using statistical characteristics obtained from experimental research. Numerical simulation LHS and Monte Carlo methods, which take into account the influences of variability of input imperfections, were employed. The influence of the utilization of the plastic reserve in the determination of the load carrying capacity of the analysed strut is shown. The influence of the initial geometric imperfections of initial strut curvature on the load carrying capacity is also presented. Santrauka Straipsnyje pateikta plienbetonio pastatu elementu didžiausiu ribiniu būkliu stochastine analize, analizuojama plienbetonio kolonu, sudarytu iš plieniniu profiliuočiu, padengtu didelio stiprio betonu, laikomoji galia gniuždant. Pirmoje straipsnio dalyje išvardytos kolonos teorines laikomosios galios nustatymo prielaidos. Tamprumo ir plastiškumo principai taikyti itempiams betono ir plieno skerspjūviuose nustatyti. Nustatytos medžiagu ir geometriniu defektu statistines charakteristikos, teorines analizes rezultatai palyginti su eksperimentiniu tyrimu rezultatais. Teorines analizes metu gautu rezultatu statistines charakteristikos patikrintos taikant iš eksperimentiniu tyrimu gautus statistinius rodiklius. Pritaikytas skaitinis modeliavimas LHS ir Monte Karlo metodais, kurie ivertina pradiniu defektu kintamumo itaka. Parodyta plastiškumo atsargos naudojimo itaka, nustatant analizuojamojo statramsčio laikomaja galia, pateikta pradinio statramsčio išlinkio pirminiu geometriniu defektu itaka laikomajai galiai.
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Chanda Nagarajan, Pratheeba, Henrik Ström et Jonas Sjöblom. « Transient Flow Uniformity Evolution in Realistic Exhaust Gas Aftertreatment Systems Using 3D-CFD ». Emission Control Science and Technology 8, no 3-4 (3 novembre 2022) : 154–70. http://dx.doi.org/10.1007/s40825-022-00217-6.
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AbstractTo precisely control a vehicle powertrain to minimize emissions, accurate and detailed models are needed to capture the spatio-temporal variability of the variables of interest. The aim of this work is to analyze flow and temperature fields in a geometrically realistic — and thus complex — exhaust gas aftertreatment system under transient conditions. The spatio-temporal response of these fields to upstream step changes is predicted using three-dimensional unsteady Reynolds-averaged Navier-Stokes (URANS) $$\kappa - \omega$$ κ - ω simulations where the catalytic converter is described as a porous medium. A catalytic converter geometry with a 90$$^{\circ }$$ ∘ -bend and a partially dead volume is used to demonstrate the effects of time-resolved flow maldistribution on the profiles of velocity and temperature. Two sets of transient simulations in terms of step changes in velocity and temperature are performed. Uniformity indices are used to characterize the distribution and variability of the different catalyst channels under transient conditions. The evolution of the uniformity indices as functions of time and axial distance into the catalyst are calculated at different cross-sectional planes. The results show that the evolution of the temperature uniformity is rate controlling, continuously modulating the otherwise much faster flow uniformity response via the fluid properties. The temperature uniformity time scale is determined by the balance of flow, thermal inertia, and the heat losses from the system. The interplay between pressure drop and heat losses governs the transition to the new steady state in uniformity. These types of transient simulations and analyses can contribute essential information when developing reduced-order engineering models to represent the spatio-temporal variability in exhaust aftertreatment systems, in particular during rapid events such as cold start.
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Mallick, Kaushik, Rushati Dey, Uttaran Bandyopadhyay, Arna Mazumder, Subrata Gayen, Mohd Ali, Gaurab Nandi Das et al. « Taxonomy and ecology of genus Psyra Walker, 1860 (Lepidoptera : Geometridae : Ennominae) from Indian Himalaya ». PLOS ONE 17, no 4 (13 avril 2022) : e0266100. http://dx.doi.org/10.1371/journal.pone.0266100.
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The Psyra Walker, 1860, is a typical Sino-Himalayan genus of the subfamily Ennominae, currently known by 18 species/4 subspecies globally and 9 species from India. This study aims to revise the taxonomy and ecology of Indian Psyra by providing a morphology-based diagnostic key, highlighting their altitudinal, habitat and seasonal preferences, and modelling their distribution based on current and future climatic scenarios. Here, we describe a new species, P. variabilis sp. nov. and document 4 species and 1 subspecies as new to India, viz. P. gracilis, P. szetschwana, P. dsagara, P. falcipennis and P. debilis debilis, thus updating the global species count to 19 with 14 species/1 subspecies from India. We also submitted partial mitochondrial COI sequences of P. crypta, P. similaria, P. spurcataria and P. gracilis as novel to the global genetic database and calculated the overall genetic divergence was 5.17% within the genus, suggesting strong monophyly. Being a typical montane genus, most of the species of Psyra were active within 2000–2280 m altitude, 10.55–15.7°C annual mean temperature, 1200–2300 mm annual precipitation and 168–179 NDVI. Psyra species were predominant in wet temperate, mixed coniferous and moist temperate deciduous forests, their abundance and richness being at peak during post-monsoon months of October–November. The major bioclimatic variables influencing the overall distribution of the genus were mean temperature of warmest quarter, temperature seasonality and precipitation of coldest/driest quarter. While two of the modelled species were predicted to lose area occupancy under future climatic scenarios, the narrow-specialist, Trans-Himalayan species P. debilis debilis was projected to gain up to 75% additional area in the years 2041–60. The results of this study will be helpful to identify sites with maximum area loss projection in ecologically fragile Indian Himalaya and initiating conservation management for such climatically vulnerable insect species groups.
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Jarkas, Abdulaziz M. « THE IMPACTS OF BUILDABILITY FACTORS ON FORMWORK LABOUR PRODUCTIVITY OF COLUMNS ». JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 16, no 4 (31 décembre 2010) : 471–83. http://dx.doi.org/10.3846/jcem.2010.53.
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The impacts of buildability on formwork labour productivity of major in situ reinforced concrete elements such as, foundations, walls, columns, beams and slabs, are yet to be determined and quantified. The labour unit cost of columns formwork, in comparison with other constituents of the reinforced concrete frame, is constantly higher due to the forming complexity of these elements, especially non‐rectangular shapes, and the small output achieved in the operation. Therefore, the objective of this research is to investigate the impacts of buildability factors on columns formwork labour productivity. To achieve this objective, a large volume of productivity data was collected and analyzed using the categorical‐regression method. As a result, the impacts of the grid patterns, variability of column sizes, repetition, total and aver‐age shutter size, and geometry of columns are quantified. Apart from the variability of column sizes, the findings show significant effects of these factors on labour productivity, which can be used to provide designers feedback on how well their designs consider the requirements of buildability principles, and the consequences of their decisions on labour efficiency. Moreover, the depicted patterns of results may provide guidance to construction managers for effective activity planning and efficient labour utilization. Santrauka Statybos veiksniu itaka gelžbetoniniu konstrukciju, kaip antai pamatu, sienu, kolonu, siju ir perdangos plokščiu, klojiniu, irengimo darbo našumui turi būti nustatyta ir kiekybiškai ivertinta. Vienetines darbo sanaudos kolonos klojiniams irengti, palyginti su kitomis gelžbetoninio remo dalimis, yra didesnes, nes sudetinga suformuoti elementus, ypač kai kolonos yra ne stačiakampio formos. Todel šio tyrimo tikslas – nustatyti statybos veiksniu itaka kolonu klojiniu irengimui. Siekiant šio tikslo buvo surinkta daug duomenu apie darbo našuma ir šie duomenys buvo ištirti naudojant kategoriju‐regresijos metoda. Buvo ivertinti šie veiksniai: ašiu tinklas, kolonu dydžio ivairove, kartojimasis, bendrasis ir vidutinis užrakto dydis, geometrija. Neivertinus kolonu dydžio ivairoves, gauti rezultatai rodo didžiuli šiu veiksniu poveiki darbo našumui. Naudojantis šia informacija galima ivertinti, ar projektuotojas atsižvelge i statybos principus ir priimtu sprendimu itaka darbo našumui. Be to, rezultatai gal suteikti papildomos informacijos darbu vadovui, kaip efektyviau panaudoti darbo jega.
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Perkins, Lenora D., Kevin W. Stafford et Wesley A. Brown. « Characterization and Delineation of Potential Evaporite Geohazards Using Electrical Resistivity Methods along FM 2185, Culberson County, Texas ». Gulf Coast Association of Geological Societies Journal 12 (2013) : 97–105. http://dx.doi.org/10.62371/nmwq7154.
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Extensive karst development within the Delaware Basin of West Texas and southeastern New Mexico poses a significant threat to infrastructure. Dissolution of regional evaporite strata have led to karst geohazards including sinkholes, subsidence features, and caves. The study area is located within the Gypsum Plain in Culberson County, Texas, and includes outcrops of Permian Castile and Rustler strata that host gypsum karst. Land reconnaissance surveys conducted during summer of 2019 documented numerous surface karst features proximal to Farm to Market Road 2185 (FM 2185). In combination with traditional survey techniques, electrical resistivity methods were used to delineate karst features along a 48 km segment of FM 2185. Capacitively-coupled resistivity (CCR) and direct-current resistivity (DCR) methods were used to characterize evaporite karst features that do not manifest surficially but pose potential geohazard concerns. CCR data were acquired using the Geometrics OhmMapper G–858 resistivity system, which uses a dipole-dipole configuration composed of five receivers connected by 2.5 m coaxial cables and a transmitter offset of 2.5 m. In combination with the medium analyzed, this geometric configuration enabled resistivity soundings up to 2.5 m deep. DCR data was collected with a SuperSting (R8/IP) multi-electrode earth resistivity meter using 112 electrodes with 2 m spacing and a dipole-dipole array configuration. This enabled a depth of investigation of up to 25 m. Data were processed using Advanced Geosciences Inc.’s (AGI’s) EarthImager 2D software and used to delineate and characterize karst-related geohazards in the shallow subsurface within the study area. Five sites are presented to demonstrate karst variability and electrical resistivity method effectiveness in geohazard detection in gypsum strata.
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Polini, Wilma, et Andrea Corrado. « Two numerical tools for geometrical deviation management in composite assemblies : a comparison ». Journal of Composite Materials, 22 octobre 2020, 002199832096705. http://dx.doi.org/10.1177/0021998320967051.
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The present work compares two numerical tools to predict the geometrical deviations of an assembly constituted by thin laminates in composite material. The first one is based on a virtual representation of both the manufacturing and the assembling processes, able to generate the variability meta-model for each component to be used in a skin-based assembly. The second one estimates the sensitivity matrix that connects the components’ variations to the assembly’s variations in the method of influence coefficients (MIC). They were experimentally verified on a case study. The comparison underlined the critical issue of both the tools.
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Zazo Del dedo, Santiago, Hector Macian-Sorribes, Cristina Maria Sena Fael, Ana-María Garía-Martín, Jose-Luis Molina et Manuel P. Pulido-Velazquez. « Qualitative Approach for Assessing Runoff Temporal Dependence Through Geometrical Symmetry ». KnE Engineering, 2 juin 2020. http://dx.doi.org/10.18502/keg.v5i6.7106.
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Currently, noticeable changes in traditional hydrological patterns are being observed on the short and medium-term. These modifications are adding a growing variability on water resources behaviour, especially evident in its availability. Consequently, for a better understanding/knowledge of temporal alterations, it is crucial to develop new analytical strategies which are capable of capturing these modifications on its temporal behaviour. This challenge is here addressed via a purely stochastic methodology on annual runoff time series. This is performed through the propagation of temporal dependence strength over the time, by means of Causality, supported by Causal Reasoning (Bayes’ theorem), via the relative percentage of runoff change that a time-step produces on the following ones. The result is a dependence mitigation graph, whose analysis of its symmetry provides an innovative qualitative approach to assess time-dependency from a dynamic and continuous perspective against the classical, static and punctual result that a correlogram offers. This was evaluated/applied to four Spanish unregulated river sub-basins; firstly on two Douro/Duero River Basin exemplary case studies (the largest river basin at Iberian Peninsula) with a clearly opposite temporal behaviour, and subsequently applied to two watersheds belonging to Jucar River Basin (Iberian Peninsula Mediterranean side), characterised by suffering regular drought conditions.
Keywords: Causal reasoning, Theorem of Bayes, Temporal dependence propagation, Runoff time series, Water resources management
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Calero Castro, Francisco José, Andrés Padillo Eguía, Virginia Durán Muñoz‐Cruzado, Luis Tallón Aguilar, José Tinoco González, Imán Laga, Fernando de la Portilla de Juan, Felipe Pareja Ciuró et Javier Padillo Ruiz. « Personalized additive manufacturing of devices for the management of enteroatmospheric fistulas ». Bioengineering & ; Translational Medicine, 26 septembre 2023. http://dx.doi.org/10.1002/btm2.10583.
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AbstractAdditive manufacturing techniques allow the customized design of medical devices according to the patient's requirements. Enteroatmospheric fistula is a pathology that benefits from this personalization due to its extensive clinical variability since the size and morphology of the wound differ extensively among patients. Standard prosthetics do not achieve proper isolation of the wound, leading to a higher risk of infections. Currently, no effective personalized technique to isolate it has been described. In this work, we present the workflow for the design and manufacture of customized devices adapted to the fistula characteristics as it evolves and changes during the treatment with Negative Pressure Wound Therapy (NPWT). For each case, a device was designed with dimensions and morphology depending on each patient's requirements using white light scanning, CAD design, and additive manufacturing. The design and manufacture of the devices were performed in 230.50 min (184.00–304.75). After the placement of the device, the wound was successfully isolated from the intestinal content for 48–72 h. The therapy was applied for 27.71 ± 13.74 days, and the device was redesigned to adapt to the wound when geometrical evolutionary changes occur during the therapy. It was observed a decrease in weekly cures from 23.63 ± 10.54 to 2.69 ± 0.65 (p = 0.001). The fistulose size was reduced longitudinal and transversally by 3.25 ± 2.56 cm and 6.06 ± 3.14 cm, respectively. The wound depth also decreased by 1.94 ± 1.08 cm. In conclusion, customization through additive manufacturing is feasible and offers promising results in the generation of personalized devices for the treatment of enteroatmospheric fistula.
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Ong, Chi Wei, Ian J. Y. Wee, Milan Toma, Fangsen Cui, Xiao Yun Xu, Arthur Mark Richards, Hwa Liang Leo et Andrew M. T. L. Choong. « Haemodynamic changes in visceral hybrid repairs of type III and type V thoracoabdominal aortic aneurysms ». Scientific Reports 13, no 1 (23 août 2023). http://dx.doi.org/10.1038/s41598-023-40323-1.
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AbstractThe visceral hybrid procedure combining retrograde visceral bypass grafting and completion endovascular stent grafting is a feasible alternative to conventional open surgical or wholly endovascular repairs of thoracoabdominal aneurysms (TAAA). However, the wide variability in visceral hybrid configurations means that a priori prediction of surgical outcome based on haemodynamic flow profiles such as velocity pattern and wall shear stress post repair remain challenging. We sought to appraise the clinical relevance of computational fluid dynamics (CFD) analyses in the setting of visceral hybrid TAAA repairs. Two patients, one with a type III and the other with a type V TAAA, underwent successful elective and emergency visceral hybrid repairs, respectively. Flow patterns and haemodynamic parameters were analysed using reconstructed pre- and post-operative CT scans. Both type III and type V TAAAs showed highly disturbed flow patterns with varying helicity values preoperatively within their respective aneurysms. Low time-averaged wall shear stress (TAWSS) and high endothelial cell action potential (ECAP) and relative residence time (RRT) associated with thrombogenic susceptibility was observed in the posterior aspect of both TAAAs preoperatively. Despite differing bypass configurations in the elective and emergency repairs, both treatment options appear to improve haemodynamic performance compared to preoperative study. However, we observed reduced TAWSS in the right iliac artery (portending a theoretical risk of future graft and possibly limb thrombosis), after the elective type III visceral hybrid repair, but not the emergency type V repair. We surmise that this difference may be attributed to the higher neo-bifurcation of the aortic stent graft in the type III as compared to the type V repair. Our results demonstrate that CFD can be used in complicated visceral hybrid repair to yield potentially actionable predictive insights with implications on surveillance and enhanced post-operative management, even in patients with complicated geometrical bypass configurations.