773 resultados para Flexible roll forming


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Reflective cracks form in pavements when hot-mix asphalt (HMA) overlays are placed over jointed and/or severely cracked rigid and flexible pavements. In the first part of the research, survival analysis was conducted to identify the most appropriate rehabilitation method for composite pavements and to evaluate the influence of different factors on reflective crack development. Four rehabilitation methods, including mill and fill, overlay, heater scarification (SCR), and rubblization, were analyzed using three performance indicators: reflective cracking, international roughness index (IRI), and pavement condition index (PCI). It was found that rubblization can significantly retard reflective cracking development compared to the other three methods. No significant difference for PCI was seen among the four rehabilitation methods. Heater scarification showed the lowest survival probability for both reflective cracking and IRI, while an overlay resulted in the poorest overall pavement condition based on PCI. In addition, traffic level was found not to be a significant factor for reflective cracking development. An increase in overlay thickness can significantly delay the propagation of reflective cracking for all four treatments. Soil types in rubblization pavement sites were assessed, and no close relationship was found between rubblized pavement performance and subgrade soil condition. In the second part of the research, the study objective was to evaluate the modulus and performance of four reflective cracking treatments: full rubblization, modified rubblization, crack and seat, and rock interlayer. A total of 16 pavement sites were tested by the surface wave method (SWM), and in the first four sites both falling weight deflectometer (FWD) and SWM were conducted for a preliminary analysis. The SWM gave close concrete layer moduli compared to the FWD moduli on a conventional composite pavement. However, the SWM provided higher moduli for the rubblized concrete layer. After the preliminary analysis, another 12 pavement sites were tested by the SWM. The results showed that the crack and seat method provided the highest moduli, followed by the modified rubblization method. The full rubblization and the rock interlayer methods gave similar, but lower, moduli. Pavement performance surveys were also conducted during the field study. In general, none of the pavement sites had rutting problems. The conventional composite pavement site had the largest amount of reflective cracking. A moderate amount of reflective cracking was observed for the two pavement sites with full rubblization. Pavements with the rock interlayer and modified rubblization treatments had much less reflective cracking. It is recommended that use of the modified rubblization and rock interlayer treatments for reflective cracking mitigation are best.

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Bio-binders can be utilized as asphalt modifiers, extenders, and replacements for conventional asphalt in bituminous binders. From the rheology results of Phase I of this project, it was found that the bio-binders tested had good performance, similar to conventional asphalt, except at low temperatures. Phase II of this project addresses this shortcoming and evaluates the Superpave performance of laboratory mixes produced with the enhanced bio-binders. The main objective of this research was to develop a bio-binder capable of replacing conventional asphalt in flexible pavements by incorporating ground tire rubber (GTR) into bio-oil derived from fast pyrolysis of agriculture and forestry residues. The chemical compatibility of the new bio-binder with GTR was assessed, and the low-temperature performance of the bio-binders was enhanced by the use of GTR. The newly developed binder, which consisted of 80 percent conventional binder and 20 percent rubber-modified bio-oil (85 percent bio-oil with 15 percent GTR), was used to produce mixes at two different air void contents, 4 and 7 percent. The laboratory performance test results showed that the performance of the newly developed bio-binder mixes is as good as or better than conventional asphalt mixes for fatigue cracking, rutting resistance, moisture sensitivity, and low-temperature cracking. These results need to be validated in field projects in order to demonstrate adequate performance for this innovative and sustainable technology for flexible pavements.

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Research into the anatomical substrates and "principles" for integrating inputs from separate sensory surfaces has yielded divergent findings. This suggests that multisensory integration is flexible and context dependent and underlines the need for dynamically adaptive neuronal integration mechanisms. We propose that flexible multisensory integration can be explained by a combination of canonical, population-level integrative operations, such as oscillatory phase resetting and divisive normalization. These canonical operations subsume multisensory integration into a fundamental set of principles as to how the brain integrates all sorts of information, and they are being used proactively and adaptively. We illustrate this proposition by unifying recent findings from different research themes such as timing, behavioral goal, and experience-related differences in integration.

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Low pressure partial melting of basanitic and ankaramitic dykes gave rise to unusual, zebra-like migmatites, in the contact aureole of a layered pyroxenite-gabbro intrusion, in the root zone of an ocean island (Basal Complex, Fuerteventura, Canary Islands). These migmatites are characterised by a dense network of closely spaced, millimetre-wide leucocratic segregations. Their mineralogy consists of plagioclase (An(32-36)), diopside, biotite, oxides (magnetite, ilmenite), +/-amphibole, dominated by plagioclase in the leucosome and diopside in the melanosome. The melanosome is almost completely recrystallised, with the preservation of large, relict igneous diopside phenocrysts in dyke centres. Comparison of whole-rock and mineral major- and trace-element data allowed us to assess the redistribution of elements between different mineral phases and generations during contact metamorphism and partial melting. Dykes within and outside the thermal aureole behaved like closed chemical systems. Nevertheless, Zr, Hf, Y and REEs were internally redistributed, as deduced by comparing the trace element contents of the various diopside generations. Neocrystallised diopside - in the melanosome, leucosome and as epitaxial phenocryst rims - from the migmatite zone, are all enriched in Zr, Hf, Y and REEs compared to relict phenocrysts. This has been assigned to the liberation of trace elements on the breakdown of enriched primary minerals, kaersutite and sphene, on entering the thermal aureole. Major and trace element compositions of minerals in migmatite melanosomes and leucosomes are almost identical, pointing to a syn- or post-solidus reequilibration on the cooling of the migmatite terrain i.e. mineral-melt equilibria were reset to mineral-mineral equilibria. (C) 2007 Elsevier B.V. All rights reserved.

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BACKGROUND: Colonic endoscopic submucosal dissection (ESD) is challenging as a result of the limited ability of conventional endoscopic instruments to achieve traction and exposure. The aim of this study was to evaluate the feasibility of colonic ESD in a porcine model using a novel endoscopic surgical platform, the Anubiscope (Karl Storz, Tüttlingen, Germany), equipped with two working channels for surgical instruments with four degrees of freedom offering surgical triangulation. METHODS: Nine ESDs were performed by a surgeon without any ESD experience in three swine, at 25, 15, and 10 cm above the anal verge with the Anubiscope. Sixteen ESDs were performed by an experienced endoscopist in five swine using conventional endoscopic instruments. Major ESD steps included the following for both groups: scoring the area, submucosal injection of glycerol, precut, and submucosal dissection. Outcomes measured were as follows: dissection time and speed, specimen size, en bloc dissection, and complications. RESULTS: No perforations occurred in the Anubis group, while there were eight perforations (50 %) in the conventional group (p = 0.02). Complete and en bloc dissections were achieved in all cases in the Anubis group. Mean dissection time for completed cases was statistically significantly shorter in the Anubis group (32.3 ± 16.1 vs. 55.87 ± 7.66 min; p = 0.0019). Mean specimen size was higher in the conventional group (1321 ± 230 vs. 927.77 ± 229.96 mm(2); p = 0.003), but mean dissection speed was similar (35.95 ± 18.93 vs. 23.98 ± 5.02 mm(2)/min in the Anubis and conventional groups, respectively; p = 0.1). CONCLUSIONS: Colonic ESDs were feasible in pig models with the Anubiscope. This surgical endoscopic platform is promising for endoluminal surgical procedures such as ESD, as it is user-friendly, effective, and safe.

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The coefficients of relative strength (CORS) of base courses for use in the American association state highway officials (AASHO) interim guide for the design of flexible pavements are determined here. Based on (1) volumetric strain--axial strain relationships at minimum volume, and (2) effective stress ratio-cohesion relationships at maximum effective stress ratio, CORS were determined from the results of laboratory triaxial tests on both asphalt-treated and untreated aggregate base course materials. The researchers conclude that volumetric strain-axial strain at minimum volume appear to be appropriate parameters for determining CORS.

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The object of this research project is to construct and evaluate several bituminous concrete base overlays with various high penetration bituminous products which have the potential to reduce future maintenance and construction costs. In September of 1981 nine different bituminous test sections were constructed on Osceola County roads A-34 and A-46 east of Ashton. Asphalt binders used were AC-5 asphalt cement, SC-800 liquid asphalt, MC-3000 cutback asphalt, CSS-1 emulsion and HFMS-2 emulsion. Aggregate for four of the test sections consisted of salvaged bituminous pavement and new aggregate combined. Each section was road mixed using a different binder arid placed 2-1/4" thick with a motor patrol. The other five test sections consisted of an AC-5 Type B asphalt concrete control section and four plant-mixed, cold-laid bituminous concrete overlay sections using new aggregate. The material was mixed in a continuous drum mix plant and laid with a full width paver.

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Cet article interroge les pratiques familiales transnationales dans la diaspora chinoise à partir d'une étude plurigénérationnelle de la communauté chinoise en Polynésie française. Il conceptualise la notion de « parenté flexible » afin d'examiner comment la famille est mise au service de stratégies d'accumulation de divers capitaux culturels, symboliques, économiques mais aussi juridiques. La parenté flexible recouvre l'ensemble des pratiques consistant à jouer sur l'agencement et la composition de la famille en vue de s'ajuster aux, et de bénéficier des différentiels entre régimes et conjonctures en situation transnationale.Flexible Kinship. Family Adjustments and Capital Accumulation within the Chinese Diaspora in French PolynesiaDrawing from a multigenerational study of the Chinese community in French Polynesia, this article deals with transnational family practices in the Chinese diaspora. It conceptualizes the notion of "flexible kinship" to examine how family is used to develop strategies to accumulate various types of capital (cultural, symbolic, economic, as well as legal). Flexible kinship covers a range of practices that consist in playing on the arrangement and composition of the family group with the aim of adjusting to and profiting from differentials in regimes and conjunctures in a transnational situation.

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Koneuusintojen sekä täysin uusien konelinjojen myötä SC-paperin valmistuskapasiteettia on tullut ja tulee paljon lisää 2000-luvulla. Uudistettujen sekä uusien linjojen tuottavuudet ja laatutasot ylittävät huomattavasti Myllykoski Paperin PK7:n nykyisen tason. Tämän vuoksi PK7:lla tulee pystyä valmistamaan vähemmän kilpailtuja ja jalostusarvoltaan parempia laatuja kuin mitä suurimmat SC-tuottajat valmistavat. Työn tavoitteena oli antaa vastauksia investointitarpeisiin, jos PK7:n tuotesuuntaa ollaan muuttamassa. Toisena tavoitteena oli luoda puristin- ja viiraosan vedenpoiston kannalta ajoikkuna, jossa muuttujna ovat neliömassa, paperikoneen nopeus sekä massatärkkelyksen määrä Kirjallisuusosassa tarkasteltiin SC-paperikoneen viira- ja puristinosan vedenpoistoa. PK7:n nykyisen listakenkäformerin vedenpoistokapasiteetti voi olla riittämätön nykyisellä laatutasolla ja hiokemassoilla suurempia ajonopeuksia tavoiteltaessa. Ongelmiksi voivat tulla listakengän vedenpoisto ja viiraosan jälkeinen kuiva-aine. Puristinosalla paksut lajit, alhainen kuiva-aine sekä nopea ja äkillinen vedenpoisto voivat aiheuttaa telanipissä kurausta. Kokeellisessa osassa selvitettiin raskaiden ja ohuiden neliömassojen sekä eripaperilajien mahdolliset vedenpoiston rajoitukset viira- ja puristinosalla. Formeritelan ja listakengän sekä 1. puristimen vedenpoistokapasiteetit tulivat koeajon perusteella kriittiseksi raskailla lajeilla ja suurilla massatärkkelysmäärillä, kun koneen nopeus nousi yli 1240 m/min.

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OBJECTIVES Guidelines proposed bioprosthesis implantation for aortic valve disease if the patients were at least 65 years old at the time of surgery, with a trend towards even younger patients in recent years. Considering the adverse effects of lifetime anticoagulation, new biological valves (less prone to degeneration) and new technologies may lead patients and surgeons to different choices. Therefore, it is interesting to analyse the results of aortic bioprosthetic valve replacement in patients aged <65 years at the time of surgery. METHODS From January 2000 to December 2010, 84 patients aged <65 years at the time of surgery had undergone an aortic bio-prosthetic valve replacement. A mid-term follow-up [(FU) mean FU time: 54.4 ± 39.2 months] was done in August 2011 in all patients (FU completeness: 100%). Results were compared with patients who had a mechanical prosthetic aortic valve replacement during the same period. RESULTS The reoperation rate for structural valve degeneration (SVD) of bioprostheses was 6% and occurred exclusively among patients <56 years. Contraindications for anticoagulation determined the choice of a bioprosthesis among 83% of these patients. The personal preference to avoid anticoagulation was the leading cause in 68% of the older patients (56-65 years). Neurological complications occurred more frequently in the mechanical control group. CONCLUSIONS Reoperations for SVD after bioprosthesis implantation occurred exclusively among younger patients (<56 years), not suitable for systemic anticoagulation. Previous studies, together with our experience, are in favour of an age limit between 56 and 60 years, taking into consideration alternative transcatheter approaches to SVD treatment.

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Diplomityön tavoitteena oli selvittää kartonkikitaformerin formeritelan alipaineen vaikutusta vedenpoistoon ja rainan ominaisuuksiin. Kirjallisuusosuudessa selvitetään erilaisten vedenpoistotapahtumien teoreettisia vedenpoistokaavoja sekä niiden avulla laskettuja vedenpoistopaineita. Kokeellisessa osuudessa verrataan vedenpoistopaineen ja vedenpoistomäärän mandollista suhdetta. Kokeiden perusteella voi todeta, että alipaineella voi vaikuttaa kokonaisvedenpoistoon sekä vedenpoistojakaumaan. Vedenpoistopaineen ja poistuneen vesimäärän välistä riippuvuussuhdetta ei useimmissa tutkituissa vedenpoistotapahtumissa ollut havaittavissa. Nykyiset vedenpoistopaineen yhtälöt kattavat tela-alueen vedenpoistotapahtumat vain osittain. Tela-alueen vedenpoistotapahtumien ja erilaisten riippuvuussuhteiden ymmärtäminen vaatii tulevaisuudessa vielä enemmän tutkimustyötä.

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Tämä diplomityö käsittelee kartonginmuovaukseen käytettävien puristintyökalujen kehittämistä. Työntavoitteina oli kehittää työkalutekniikan suunnittelua ja valmistusta edullisemmaksi, nopeammaksi ja työkaluja toiminnoiltaan tehokkaammiksi. Työn tuli sisältää myös ohjeet työkalujen suunnittelemiseksi ja valmistamiseksi jatkoa ajatellen. Työn aikana selvitettiin mahdollisia työkalurakennevaihtoehtoja, valmistusmateriaaleja sekä niiden käsittelymenetelmiä ja lastuamista sekä sen tarjoamia mahdollisuuksia valmistusmenetelmänä. Työkalupari suunniteltiin modulaariseksi siten, että uusia työkaluja varten vain osa komponenteista täytyy valmistaa uudelleen, samalla työkalun osien lukumäärää pienennettiin merkittävästi. Valmistusmateriaaliksi valittiin hyvin lastuttava työkaluteräs ja sen koneistaminen tapahtui vaakakaraisessa koneistuskeskuksessa. Työn loppuvaiheessa työkalukokonaisuudelle tehtiin kustannuslaskelma jaoteltuna eri työvaiheille sekä komponenteittain. Työkalu asennettiin puristimeen ja sille suoritettiin käyttötestaus. Työn aikana karttuneen kokemuksen sekä koekäytön perusteella tehtiin jatkokehitysehdotuksia.

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Tutkimus keskittyy kansainväliseen hajauttamiseen suomalaisen sijoittajan näkökulmasta. Tutkimuksen toinen tavoite on selvittää tehostavatko uudet kovarianssimatriisiestimaattorit minimivarianssiportfolion optimointiprosessia. Tavallisen otoskovarianssimatriisin lisäksi optimoinnissa käytetään kahta kutistusestimaattoria ja joustavaa monimuuttuja-GARCH(1,1)-mallia. Tutkimusaineisto koostuu Dow Jonesin toimialaindekseistä ja OMX-H:n portfolioindeksistä. Kansainvälinen hajautusstrategia on toteutettu käyttäen toimialalähestymistapaa ja portfoliota optimoidaan käyttäen kahtatoista komponenttia. Tutkimusaieisto kattaa vuodet 1996-2005 eli 120 kuukausittaista havaintoa. Muodostettujen portfolioiden suorituskykyä mitataan Sharpen indeksillä. Tutkimustulosten mukaan kansainvälisesti hajautettujen investointien ja kotimaisen portfolion riskikorjattujen tuottojen välillä ei ole tilastollisesti merkitsevää eroa. Myöskään uusien kovarianssimatriisiestimaattoreiden käytöstä ei synnytilastollisesti merkitsevää lisäarvoa verrattuna otoskovarianssimatrisiin perustuvaan portfolion optimointiin.

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El present treball busca trobar si hi ha diferències significatives entre la fusta en roll i la fusta en roll amb una cara feta per a la fusta de Pinus nigra, en la resistència mecànica, concretament en la resistència a compressió paral lela a la fibra i la resistència a flexió. També s ha buscat si es pot relacionar aquestes resistències amb un mètode no destructiu com és la velocitat d ultrasons.

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The present study was done with two different servo-systems. In the first system, a servo-hydraulic system was identified and then controlled by a fuzzy gainscheduling controller. The second servo-system, an electro-magnetic linear motor in suppressing the mechanical vibration and position tracking of a reference model are studied by using a neural network and an adaptive backstepping controller respectively. Followings are some descriptions of research methods. Electro Hydraulic Servo Systems (EHSS) are commonly used in industry. These kinds of systems are nonlinearin nature and their dynamic equations have several unknown parameters.System identification is a prerequisite to analysis of a dynamic system. One of the most promising novel evolutionary algorithms is the Differential Evolution (DE) for solving global optimization problems. In the study, the DE algorithm is proposed for handling nonlinear constraint functionswith boundary limits of variables to find the best parameters of a servo-hydraulic system with flexible load. The DE guarantees fast speed convergence and accurate solutions regardless the initial conditions of parameters. The control of hydraulic servo-systems has been the focus ofintense research over the past decades. These kinds of systems are nonlinear in nature and generally difficult to control. Since changing system parameters using the same gains will cause overshoot or even loss of system stability. The highly non-linear behaviour of these devices makes them ideal subjects for applying different types of sophisticated controllers. The study is concerned with a second order model reference to positioning control of a flexible load servo-hydraulic system using fuzzy gainscheduling. In the present research, to compensate the lack of dampingin a hydraulic system, an acceleration feedback was used. To compare the results, a pcontroller with feed-forward acceleration and different gains in extension and retraction is used. The design procedure for the controller and experimental results are discussed. The results suggest that using the fuzzy gain-scheduling controller decrease the error of position reference tracking. The second part of research was done on a PermanentMagnet Linear Synchronous Motor (PMLSM). In this study, a recurrent neural network compensator for suppressing mechanical vibration in PMLSM with a flexible load is studied. The linear motor is controlled by a conventional PI velocity controller, and the vibration of the flexible mechanism is suppressed by using a hybrid recurrent neural network. The differential evolution strategy and Kalman filter method are used to avoid the local minimum problem, and estimate the states of system respectively. The proposed control method is firstly designed by using non-linear simulation model built in Matlab Simulink and then implemented in practical test rig. The proposed method works satisfactorily and suppresses the vibration successfully. In the last part of research, a nonlinear load control method is developed and implemented for a PMLSM with a flexible load. The purpose of the controller is to track a flexible load to the desired position reference as fast as possible and without awkward oscillation. The control method is based on an adaptive backstepping algorithm whose stability is ensured by the Lyapunov stability theorem. The states of the system needed in the controller are estimated by using the Kalman filter. The proposed controller is implemented and tested in a linear motor test drive and responses are presented.