Academic literature on the topic 'Guide d'onde à section variable'
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Journal articles on the topic "Guide d'onde à section variable"
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Liu, Zhi Feng, and Bo Hua Zhang. "Static Analysis of Variable Cross-Section Beam Carrying a Moving Heavy Load." Applied Mechanics and Materials 575 (June 2014): 329–36. http://dx.doi.org/10.4028/www.scientific.net/amm.575.329.
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The problem of variable cross-section beam carrying a moving heavy load is investigated. UG software is used to build a three-dimensional model of the beam. The finite difference method and finite element method are used static analysis for the variable cross-section beam carrying a moving heavy load. The static deformation of the beam guide surface is obtained. Comparing the data of the two method, the feasibility of the method is verified. This paper give a guide surface load curve research method of variable cross-section beam carrying a moving heavy load.
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Hang, Gang, and Jin Fu Wu. "Research on Influence of Fatigue Life from Variable Cross-Section Strut-and-Tie Transition Zone Radian." Advanced Materials Research 145 (October 2010): 321–25. http://dx.doi.org/10.4028/www.scientific.net/amr.145.321.
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There is so much influence to the fatigue life of the whole structural component from cross-section transition zone radian, and more than 100 times difference is made by different structural details for fatigue life [1]. According to structure and features of variable cross-section strut-and-tie,combing with its’ geometric properties and applied stress ways, at the basis of nominal stress method, the fatigue life of variable cross-section strut-and-tie is analyzed in the paper. Then, transitional zone is improved and fatigue life is analyzed. At last, the improved is compared with previous structure and analysis of Influence of fatigue life from variable cross-section strut-and-tie transition zone radian in theoretical. The conclusions of this paper guide other similar researches.
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Peng, Wen Fang, Qiang Li, and Yu Yan. "FEA Analysis on 600MPa TRIP Steel Variable Section Roll Forming with Protrusion and Hole." Advanced Materials Research 457-458 (January 2012): 299–303. http://dx.doi.org/10.4028/www.scientific.net/amr.457-458.299.
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Trip steel is broadly used in automobile manufacturing with its high strength and enhanced formability. For the variable section parts with protrusion and hole, roll forming is a kind of feasible way to realize continuous parts manufacturing, In the paper, with deep understanding of roll forming process and reasonable simplification, the FEM model of a multi-step variable section roll forming of 600MPa trip steel parts with protrusion and hole is established to analyze the mechanics and the deformation characteristics of the forming procedure. Equivalent stress, equivalent strain, sheet thickness and springback amount are extracted from the simulation result and studied comparatively, which is of great importance to understand the appearance of the forming defects. In addition, the forming load and torque of the rollers can also be obtained to guide the design of the variable section roll forming product line.
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Xiang, Min, and Cong Juan Yang. "Analysis of Eccentric Load Causing Torsion Effects of Variable Cross-Section Continuous Box Girder during Cantilevered Casting." Advanced Materials Research 446-449 (January 2012): 1194–98. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.1194.
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The construction with hanging basket eccentric loading was studied for the cantilever casting of a 32m +48 m +32 m continuous box girder. The calculation of center deflecting angles of cantilever box girders with variable cross-section due to pure torsion was derived, and correspondingly a program was developed to calculate this formula. An analysis model of cantilever casting continuous beam bridge with hanging basket eccentric loading was established based on finite elements software, and the shear stress, the longitudinal normal stress and the combined stress of different section were analyzed under different construction process. The torsional effect due to hanging basket eccentric loading was studied and the results are helpful to guide the construction in practice.
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Yu, Shu, and Lin Lü. "Optimization of the selective catalytic reduction structure of a vehicle based on the improvement in the uniformity of the nitrogen oxides distribution." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 2 (March 8, 2017): 188–99. http://dx.doi.org/10.1177/0954407017694276.
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As the sensor probe occupies a small proportion of the cross-sectional area of the pipe, the concentration of nitrogen oxides measured by the sensor may not reflect the average concentration of nitrogen oxides at the measured section when the uniformity of the nitrogen oxides is poor. The uniformity of the nitrogen oxides at the measured section is influenced by the structure of the selective catalytic reduction system of the vehicle, and particularly by the structure of the variable cross-section behind the catalyst. In this paper, a model of the selective catalytic reduction system is established to explore the rules for influencing the uniformity of the nitrogen oxides. The conclusion shows that the uniformity of the nitrogen oxides is influenced by five structure factors, which are as follows: the nozzle location; the structure of the mixing chamber; the exhaust velocity; the pipe-diameter ratio of the variable-cross-section structure; the distance between the measured section and the catalyst and the catalyst outlet. When the nozzle is further away from the catalyst inlet and the mixing chamber is designed as a cone-shaped guide plate, the uniformity of the nitrogen oxides is better. When the relative flow velocity is greater than 4.5–7.5 s−1, the uniformity of the nitrogen oxides is positively related to this factor; otherwise, the uniformity stays invariant. When the pipe-diameter ratio of the variable cross-section is 0.34, the uniformity of the nitrogen oxides is the best. The distance between the measured section and the catalyst outlet is logarithmically related to the uniformity of the nitrogen oxides. Based on the laws for the parameters influencing the uniformity of the nitrogen oxides, the structure of selective catalytic reduction in a vehicle can be optimized to improve the objectivity of the measurements, thereby guaranteeing the accuracy of the vehicle’s on-board diagnostic system, in which the nitrogen oxides sensor is applied.
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Dong, Liangliang, Jing Wang, and Xiaohua Zhu. "Design and mechanical behavior study of ultrahigh-torque variable pitch casing joint." Advances in Mechanical Engineering 11, no. 1 (January 2019): 168781401881408. http://dx.doi.org/10.1177/1687814018814084.
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The top drive for casing running system can effectively avoid borehole neck down and sticking, reducing construction period by about 50%. However, the casing will bear higher torque load, and the casing joint threads can meet the bearing performance, which have a critical impact on casing running and the life of oil and gas wells. Variable pitch can reduce thread stress concentration and improve load-bearing strength. Lacking research on mechanical behavior has greatly restricted the development of variable pitch thread. This article generated a variable pitch casing joint thread helix forming method and control equation; designed an ultrahigh-torque variable pitch casing joint thread based on the theory of screw transformation matrix; established a three-dimensional finite element model of the variable pitch casing joint; optimized the main structure parameters with the judgment of torque-bearing capacity; and conducted parameter-sensitivity evaluation of guide surface angle, bearing surface angle, pitch of box thread, and amount of varying pitch under tension load, compression load, bending load, and torque load. The designed variable pitch casing joint had been successfully used in several top driving casing running wells, downed to the maximum depth of 4375 m, the largest hole deviation angle of 55.37° and horizontal section length of about 260 m. Under a torque of 4000 N m, the top drive rotated down into the gas well successfully without failure. The research work of this article has significance on variable pitch thread and enhances the bearing capacity of the thread.
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Mohanty, Suravi, Usha Kini, Kanishka Das, Divya Puttegowda, Lokendra Yadav, Manjally Kunjipapu Babu, Kiran Mahadevappa, Prasanna Kumar, Shubha Attibele Mahadevaiah, and Mainak Deb. "Appendicular Biopsy in Total Colonic Aganglionosis." Pediatric and Developmental Pathology 20, no. 4 (February 24, 2017): 277–87. http://dx.doi.org/10.1177/1093526617692913.
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Background The reliability of intraoperative evaluation of ganglion cells in the appendix as a guide to a diagnosis of total colonic aganglionosis is unclear. Objective To evaluate the diagnostic utility of appendicular innervation in colonic Hirschsprung disease (HD) and TCA. Methods Prospective, systematic study of ganglion cells and the neural plexii in appendices from cases (HD and TCA) and age matched controls with frozen and paraffin sections, rapid acetylcholinesterase (AChE) and immunohistochemistry. Results A total of 48 appendices (28 controls, 20 cases; 19 frozen) were evaluated. Of these 48, 30 were neonates. Ganglion cell clusters were smaller in controls (28) and HD (6) than those in the rectum, distorted at places and mimicked lymphocytes and endothelial cells, especially in neonates. Complete study of 13 appendices in TCA showed absence of ganglion cells, hypertrophic nerves, AChE activity, and calretinin staining. In 2/13 TCA, an erroneous frozen section identification of ganglia was later corrected based on AChE histochemistry and a panel of IHC stains. Ileal biopsies guided the placement of a ganglionic ileostomy in all. One case each of skip segment aganglionosis in a TCA and variable hypoganglionosis in long segment colonic HD is reported. Conclusion Intraoperative characterization of appendicular innervation as a guide to the diagnosis of TCA is unreliable, in part because of the possibility of skip segment disease/variable hypoganglionosis. We propose terminal ileal biopsies for diagnosis and leveling of aganglionosis. AChE on frozen/calretinin on paraffin tissue is the best approach to avoid diagnostic errors.
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Sun, Jubo, Zhanfei Wang, Diwei Xue, and Hanbin Ge. "Concept and Behavior of a Steel Ring Restrainer with Variable Stiffness and Buffer Capacity." Journal of Earthquake and Tsunami 14, no. 04 (August 2020): 2050020. http://dx.doi.org/10.1142/s1793431120500207.
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In this paper, a novel restrainer called steel ring restrainer (SRR) is proposed to prevent the unseating of bridges. The restrainer is comprised of a steel ring, an upper guiding pulley, a downward guiding pulley, and two connections. The SRR can provide different stiffnesses under different seismic excitations. The SRR is not activated under daily load but provides smaller stiffness in small and medium earthquakes and even larger stiffness in strong earthquakes. The stiffness changes smoothly from small and medium earthquakes to strong earthquakes. This mechanism called buffer capacity reduces the impact on the connection between the SRR and structure. In order to study the effect of each design parameter on the mechanical properties of the SRR, 54 finite element (FE) models in four groups were established and analyzed. The results show that the diameter of the cross-section of the steel ring has an important influence on the initial stiffness, secondary stiffness, buffering capacity, and ultimate bearing capacity of the SRR, the radius of the curved part of the steel ring significantly affected the initial stiffness and ultimate displacement, the nonworking length of the SRR was decided by the length of the straight part of the steel ring, and the diameter of the guide pulley governed the ultimate bearing capacity and ultimate displacement. Additionally, the predicted formulas of the design parameters were derived and eight models were employed to investigate the effectiveness of the formulas, in order to be applied in the seismic design.
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Bilyk, Serhii, and Vitalina Yurchenko. "Size optimization of single edge folds for cold-formed structural members." Strength of Materials and Theory of Structures, no. 105 (November 30, 2020): 73–86. http://dx.doi.org/10.32347/2410-2547.2020.105.73-86.
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Parametric optimization problem for single edge fold size in cold-formed structural members subjected to central compression has been considered by the paper. Determination the load-bearing capacity of the cold-formed structural members has been performed using the geometrical properties calculated based on the constructed “effective” (reduced) cross-sections taking into account local buckling effects in the section as well as distortional buckling effects.
Single edge fold size in cold-formed C-profile has been considered as design variable. Linear convolution of criteria, namely minimization criterion of design area of stiffener cross-section and maximization criterion effective area of stiffener cross-section which defines it reduced load-bearing capacity due to flexural buckling has been used as optimization criterion. The parametric optimization problem has been solved using the method of objective function gradient projection onto the active constraints surface with simultaneous correction of the constraints violations. In order to realize the formulated optimization problem, software OptCAD intended to solve parametric optimization problems for steel structural systems has been used.
Optimization results of the single edge folds for the cold-formed С-profiles manufactured by «Blachy Pruszyński» company, «BF FACTORY» company as well as «STEELCO» company have been presented by the paper. The results of the performed investigation can be used as recommendations for companies-manufacturers of the cold-formed profiles, as well as a guide for creation the national assortment base of the effective cold-formed profiles promoting wider implementation of cold-formed steel structures in building practice.
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Zhang, Xiaofei, Peipei Wei, Xin Zhang, Tao Yan, Gangfeng Zheng, and Wenwei Zhang. "Experimental Study on Equivalent Strength of Induced Joints with consideration to Influence of Concrete Strength, Inducer Spacing, and Concrete Age." Advances in Civil Engineering 2020 (December 16, 2020): 1–13. http://dx.doi.org/10.1155/2020/5187264.
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To prevent the occurrence of temperature cracking, the induced joints of dams are typically arranged to reduce the tensile strength and orderly guide the crack to form at an induced joint, which can protect the dam structure. The state of the joint surface and the equivalent strength and arrangement of the induced joints have important practical significance for preventing the disorderly cracking of the dam. In this study, the concrete strength, inducer spacing, and concrete age were considered as variable conditions to perform axial tension tests on roller compacted concrete (RCC) bidirectional induced joints. A finite element software was used for numerical simulation, and the simulation results were compared with the experimental results. The equivalent strength of the RCC induced joints increased with the spacing of the induced joints, but the rate of increase gradually declined. The equivalent strength of the RCC induced joints rapidly increased in the early stage, but the strength weakening degree was different at different concrete ages. The strength weakening degree of the induced joint section decreased as the concrete strength increased. These results provide a reference for the setting of induced joints in practical engineering.
Dissertations / Theses on the topic "Guide d'onde à section variable"
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Hamitouche, Zahia. "Études expérimentales et numériques de la propagation dans des guides d'onde à section linéairement variable." Le Havre, 2008. http://www.theses.fr/2008LEHA0003.
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Le but de ce travail est de fournir des résultas expérimentaux et numériques sur le comportement d'une onde de Lamb dans des guides d'onde élastiques en duraluminium comportant une zone de section linéairement variable, localisés entre deux secteurs d'épaisseurs constantes de 2 mm et 5 mm. Ces guides d'onde ne sont différents que par la pente de leur zone de section variable. Plusieurs phénomènes ont été observés : l'adiabaticité des modes de Lamb dans la zone de section variable, leur réflexion à leur épaisseur de coupure et leur transmission en dehors de cette zone par effet tunnel en d'autres modes de Lamb (conversion de modes). Les résultats expérimentalement et numériquement obtenus montrent l'existence d'ondes adiabatiques dans tous les guides étudiés. En particulier, l'amplitude des déplacements normaux de l'onde adiabatique S0 sur la surface plane varie en fonction de l'épaisseur de la zone de section variable et montre un nombre de résonances localisées dans cette zone. Le nombre et la position des résonances varient en fonction de la pente du guide et de la zone dispersive. Dans le cas où le mode se propage vers les épaisseurs décroissantes dans un guide d'onde de forte pente, une transmission de l'onde incidente a été observée à la sortie de la zone de section variable en d'autres modes. Lorsque les modes de Lamb d'ordres supérieurs, et donc possédant un produit fréquence-épaisseur de coupure, se propagent vers les épaisseurs décroissantes, une réflexion de ces modes à leur épaisseur de coupure est observée, et ce avant d'atteindre la fin de la zone de section variable. Une faible part de leur énergie est transmise par effet tunnel en dehors de la zone de section variable en modes de Lamb différents. L'énergie des modes transmis a été mesurée et représente 2% au maximum, selon la pente du guide, de celle du mode incident. Par ailleurs, la zone de section variable montre un phénomène de filtrage fréquentiel pour les modes de Lamb ayant des produits fréquence-épaisseur de coupure. Les résultats expérimentaux sont en bon accord avec les résultats numériques. Grâce à l'étude numérique nous avons pu établir un modèle prédictif fiable et expliquer les phénomènes physiques observésThe aim of this work is to provide the experimental and numerical results on the behaviour of a Lamb wave in duraluminium elastic waveguides. These waveguides include an area of linearly varying section, located between two areas of constant thickness of 2 mm and 5 mm. These waveguides are only differing by the slope of their varying section domain. Several phenomena were observed : the adiabaticity of the Lamb modes in the area of varying section, the reflexion of an incident Lamb mode when it reaches its thickness cut-off in the varying section area and its transmission outside this zone by tunnel effect. The experimental and numerical results obtained show the existence of adiabatic waves in all the studied guides. In particular, the amplitude of normal displacements of the adiabatic S0 mode on the plane surface varies according to the thickness and shows a number of resonances located in this zone. The number and the positions of resonances are strongly depending of the varying section slope. If the same mode is propagated towards the decreasing thicknesses in a waveguide of strong slope, a transmission of this incident wave is observed at the end of the varying section domain into other modes. When the Lamb modes having cut-off are propagated towards the decreasing thicknesses, a reflexion at their thickness cut-off is observed. Nevertheless, a small part of their energy is transmitted by tunnel effect into other Lamb modes in the thinner part of the waveguide. The energy of the transmitted modes have been measured and represents a maximum of 2% of the energy of the incident mode. In addition, the varying section area shows a phenomenon of frequency filtering for the Lamb modes having cut-off. The experimental results are in good agreement with the numerical results. The numerical study allowed the obtention of a reliable predictive model and helped to highlight the physical meaning of the observed phenomenon
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Teyssandier, Benoît Depollier Claude. "Analyse dans l'espace des phases de champs acoustiques application à des guides de section variable et à des espaces clos /." [S.l.] : [s.n.], 2004. http://cyberdoc.univ-lemans.fr/theses/2004/2004LEMA1007.pdf.
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Teyssandier, Benoît. "Analyse dans l'espace des phases de champs acoustiques : application à des guides de section variable et à des espaces clos." Le Mans, 2004. http://cyberdoc.univ-lemans.fr/theses/2004/2004LEMA1007.pdf.
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L'objectif de ce travail consiste à étudier le caractère local de champs acoustiques bidimensionne scen régime harmonique au moyen de représentations conjointes (espace-nombre d'onde). A un point de coordonnées (x,y), on associe à un champ une fonction définie dans l'espace des phases (x,y,kx,ky). A l'instar de l'analyse des signaux riori-stationnaires conjointement en temps et en fréquence, le principe de l'analyse est basé sur une représentation conjointe, qualifiant simultanément la position spatiale et le contenu spectral du champ. Pour représenter une telle fonction, deux solutions sont proposées: la première associe à chaque point (x,y) du champ un spectre de nombre d'onde (k-x,k-y), nommé spectre local, et la seconde analyse le champ selon les variables de Birkhoff (s,sinf@), s etant l'abcisse curviligne le long d'une courbe appartenant au domaine d'étude, et sing étant proportionnel à la composante du vecteur d'onde tangent à cette courbe. Trois applications relevant de la propagation guidée sont développées ici. Dans le chapitre 2, les deux représentations (spectre local et variable de Birkhoffi sont appliquées en premier lieu à l'étude d'un guide droit, afin de valider leur comportement. Plusieurs distributions sont comparées: Husimi (ou Spectrogramme), Pseudo-Wigner (et sa version lissée) et Pseudo-Wigner-modifiée (ou S-Method). Ensuite, l'analyse d'une part, du champ dans un guide droit à changement brusque de section, et d'autre part dans un guide à géométrie complexe, permet d'illustrer la pertinence de ces outils. Pour ce type de problèmes. La complémentarité de ces représentations permet d'illustrer (qualitativement) des phénomènes physiques de type "galerie d'écho", "ondes rampantes" ou. . Ondes diffractées". Dans le chapitre 3, le principe de réallocation (développé dans le domaine de l'analyse des signaux non- stationnaires) de la distribution de Husimi est utilisé dans le contexte de l'étude de champs dans des espaces clos ou billard. L'étude porte sur l'analyse de billard de dynamique régulière, mixte ou irrégulière. ,En améliorant la localisation dans l'espace des phases, la réallocation favorise la lecture de certaines caractéristiques des champs comme les cicatrices. Enfin, dans le chapitre 4, l'étude des guides d'onde à section variable est développée au travers d'une analyse locale, afin d'estimer les relations de dispersion pour chacun des modes présents dans le guide. La réallocation illustre de manière évidente la présence de phénomènes physiques comme les couplages entre les modes, les transitions adiabatiques ou les phénomènes de modes piégés. En conclusion, des perspectives d'applications de ce travail sont proposées dans le cadre de problèmes inverses, de caractérisation de structures vibrantes et d'identificafion de sourcesThe airn of this work is ta study the local behavicr Of twc-dimensionai (2D) barrnonic acoustic field y rneans of a joint "space-wave nurnbee'representation. A function defined in the phase space domain (x,y,kx,ky) is assaciated ta a signal which is a function of spatial coordinates (x,y). In order ta represent such a function, @two methods are proposed ta realize it. The first is ta associate ta each point (x,y) of the wave field a 2D wave nurnber spectrurn (k-x,k-y), called local spectrum. The second is ta process by other coordinates the wave field alorig an arbitrary direction, introduced in quantum mechanics for the study of classical billiards, and is provided by the Birkhoff variables (s,sing). Three applications concerning guided propagation are developped here. In chapter 2, the two phase space diagrarns (local spectrum and Birkhoff analysis) are estirnated thanks ta uadratic phase space distributions. Simulations are presented for wave fields in a 2D planar waveguide for a pedagogical point of view with Gaussian bearn or point source excitation, and non-uniform waveguides as a sudden area expansion chamber and an open billiard with a single incoming mode at the entrarice of each of thern. Local spectrurn and Birkhoff analysis are used in order ta identify the structure hidden in the field. Ln chapter 3, the reassignrnent method is used ta analyse eigen-modes of different cavities or billiards, regarding regular, mixed or irregular billiards. This chapter shows how the reassigned Husimi distribution is used ta define specific phenomena in an elgenstate as scars. In chapter 4, the analysis of rnultimodai propagation !ri a varying cross section waveguide with the help of phase space distributions is used in order ta estirnate the local variations of the dispersion curves of the propagatinq modes. The reassignment rnethod on the Husimi distribution is an attractive tool ta define adiabatic transition, mode coupling or trapped modes. Lize inverse problem, vibrating structure
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Marical, Patrick. "Ondes guidées dans un guide élastique comportant une variation de section de type gaussienne." Le Havre, 2007. http://www.theses.fr/2007LEHA0009.
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Le but de ces travaux est d’analyser le comportement d’une onde de Lamb (S0 ou A1) quand celle-ci se propage dans des plaque en duraluminium comportant une zone de section variable de forme gaussienne. Les données sont obtenues soit d’une étude expérimentale assurée par un interféromètre laser mesurant les déplacements des ondes ou soit d’une étude numérique basée sur une méthode d’éléments finis. Ces données sont ensuite analysées par des traitements à base de FFT. Les résultats obtenus indiquent un comportement adiabatique de l’onde dans la zone gaussienne et des conversions en modes de Lamb en dehors. Les forts taux de conversions sont liés à une forte variation de la zone de section variable. Une onde partiellement piégée dans la zone gaussienne a été observée et est liée aussi au phénomène de conversions. Une étude consacrée au problème inverse permet de retrouver le profil du guide à partir des relevés expérimentauxThe aim of these works is to analyse the behavior of a Lamb wave (S0 and A1) when it propagates in plates of Duraluminium including a varying section area of Gaussian shape. The data are obtained by an experimental study composed by a Laser interferometer measuring the displacements of the waves or a numerical study based on a finite element method. These data are analysed by FFT treatments. The results obtained show an adiabatic behavior of the wave in the Gaussian area and Lamb mode conversions outside. The strong conversion rates are linked to a strong variation of the varying section area. A partially trapped wave in the Gaussian area has been observed and is linked also with the conversion phenomenon. A study devoted to an inverse problem enables to find the guide profile from the experimental data
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Zeng, Jun-chang, and 曾俊菖. "Comparisons of Variable Section Method for GUIDE and PARTY Regression Trees." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/65133578801690744344.
Full textBook chapters on the topic "Guide d'onde à section variable"
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Smith, Ronnie W., and D. Richard Hipp. "Dialog Processing Theory." In Spoken Natural Language Dialog Systems. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195091878.003.0005.
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Consider the following dialog situation. The computer is providing a human user with assistance in fixing an electronic circuit that causes a Light Emitting Diode (LED) to display in a certain way. The current focus of the task and dialog is to determine the status of a wire between labeled connectors 84 and 99, a wire needed for the circuit that is absent. Figures 3.1 and 3.2 show two possible dialog interactions that could occur at this point. In figure 3.1, the computer has total dialog control, and a total of 29 utterances are needed to guide the user through the rest of the dialog. In figure 3.2, the human user has overall dialog control, but the computer is allowed to provide direct assistance as needed (i.e. in helping add the wire). Only 11 utterances are needed for the experienced user to complete the dialog. These samples are from interactions with a working spoken natural language dialog system. To engage in such dialog interactions, a system must exhibit the behaviors mentioned at the beginning of chapter 1: (1) problem solving for providing task assistance, (2) conducting subdialogs to achieve appropriate subgoals, (3) exploiting user model to enable useful interactions, (4) exploiting context dependent expectations when interpreting user inputs, and (5) engaging in variable initiative dialogs. Achieving these behaviors while facilitating the measurement of system performance via experimental interaction requires a theory of dialog processing that integrates the following subtheories. • An abstract model of interactive task processing. • A theory about the purpose of language within the interactive task processing environment. • A theory of user model usage. • A theory of contextual interpretation. • A theory of variable initiative dialog. This chapter presents such a theory of dialog processing. Frequent reference to the dialog examples in figures 3.1 and 3.2 will guide the discussion. The first section discusses the overall system architecture that facilitates integrated dialog processing. The remainder of the chapter addresses each subtheory in turn, emphasizing how each fits into the overall architecture. The chapter concludes with a summary description of the integrated model.
Conference papers on the topic "Guide d'onde à section variable"
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Inoue, Daisuke, Takao Ueno, and Satoru Nakamura. "Robotic Inspection Tests of Tunnel Lining Concrete with Crack Light-Section Device on Variable Guide Frame." In 34th International Symposium on Automation and Robotics in Construction. International Association for Automation and Robotics in Construction (IAARC), 2018. http://dx.doi.org/10.22260/isarc2018/0074.
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Hobson, Garth V., Anthony Gannon, Wendell Holmes, Michael McCormick, and Vincent Capece. "Experimental and Numerical Performance Characterization of a Transonic Compressor Rotor Operating Behind an Inlet-Guide Vane With Variable Flap Angles." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-27308.
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The performance of a modern, forward-swept, transonic compressor rotor has been characterized operating behind an inlet-guide (IGV) vane section that has variable flaps. Testing was performed at both transonic and subsonic rotor tip speeds in an attempt to determine the off-design performance of the rotor at various flap angle settings of the IGV’s. Measurements at moderate flap angles (+20° and −10°) have been determined up to 90% speed (27,000 rpm) of the drive turbine maximum capability. Extremely high flap angles, in excess of +55°, were tested down into the low speed range. For this study the negative flap angles produced counterswirl and the positive flap angles produced swirl in the same direction as the rotation of the rotor. A rigorous definition of the mass-averaged efficiency is presented. Performance predictions were carried out using ANSYS-CFX on a single passage model consisting of both the IGV and the rotor. Reasonable comparisons with a medium mesh resolution were obatined when compared to experiment.
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Barbosa, Joa˜o Roberto, Franco Jefferds dos Santos Silva, Jesuino Takachi Tomita, and Cleverson Bringhenti. "Influence of Variable Geometry Transients on the Gas Turbine Performance." In ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46565.
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During the design of a gas turbine it is required the analysis of all possible operating points in the gas turbine operational envelope, for the sake of verification of whether or not the established performance might be achieved. In order to achieve the design requirements and to improve the engine off-design operation, a number of specific analyses must be carried out. This paper deals with the characterization of a small gas turbine under development with assistance from ITA (Technological Institute of Aeronautics), concerning the compressor variable geometry and its transient operation during accelerations and decelerations. The gas turbine is being prepared for the transient tests with the gas generator, whose results will be used for the final specification of the turboshaft power section. The gas turbine design has been carried out using indigenous software, developed specially to fulfill the requirements of the design of engines, as well as the support for validation of research work. The engine under construction is a small gas turbine in the range of 5 kN thrust / 1.2 MW shaft power, aiming at distributed power generation using combined cycle. The work reported in this paper deals with the variable inlet guide vane (VIGV) transients and the engine transients. A five stage 5:1 pressure ratio axial-flow compressor, delivering 8.1 kg/s air mass flow at design-point, is the basis for the study. The compressor was designed using computer programs developed at ITA for the preliminary design (meanline), for the axisymmetric analysis to calculate the full blade geometry (streamline curvature) and for the final compressor geometry definition (3-D RANS and turbulence models). The programs have been used interatively. After the final channel and blade geometry definition, the compressor map was generated and fed to the gas turbine performance simulation program. The transient study was carried out for a number of blade settings, using different VIGV geometry scheduling, giving indication that simulations needed to study the control strategy can be easily achieved. The results could not be validated yet, but are in agreement with the expected engine response when such configuration is used.
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Armstrong, Jeffrey, Christopher Bolin, Mohammed Ebrahim, and Michael Carney. "Development and Testing of a 333 Kilowatt Industrial Gas Turbine." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57828.
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The development of a derivative small industrial gas turbine, sometimes termed a “microturbine”, is described. The target markets were the oil and gas upstream and midstream markets, and combined heat and power applications. These applications defined the product objectives. A general description is presented of the baseline recuperated gas turbine from which the new gas turbine is derived. The new gas turbine is a 333kWe recuperated gas turbine with a modernized compressor, variable inlet guide vanes for improved part-power efficiency and emissions, and an improved hot-section. The applicability and advantages of the GT333S features are compared with the market requirements. The development program included compressor rig testing, inlet guide vane development and testing, and engine testing. For the new product, a large number of components remained unchanged from GT250S, including most of the drivetrain. This provided confidence that the reliability of the GT333S, based on the millions of successful operating hours accrued on the GT250S, would translate into good GT333S reliability and availability. Extensive factory testing was performed to demonstrate the robustness of the new engine. The final performance results showed that the gas turbine achieved the program objectives. Some lessons learned from the development program are described.
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Crosa, G., G. Ferrari, and A. Trucco. "Modelling and Recoupling the Control Loops in a Heavy-Duty Gas Turbine Plant." In ASME 1995 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/95-gt-061.
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This paper presents a dynamic simulation of a single shaft heavy-duty gas turbine plant, suitable for gas-steam combined cycles. The plant is operated at maximum gas turbine exhaust temperature, using variable inlet guide vanes (VIGV) as control. In the first section, a non-linear lumped parameter mathematical model is described: it includes a control system representative of those controls normally utilised by industry today. Some dynamic responses of a controlled plant taken as an example are presented. In the second section, a different control system is proposed, operating with no interaction between the speed and exhaust temperature loops. To this aim, a linear model in the frequency domain of the uncontrolled plant is obtained, starting from the non-linear model in the time domain. Assuming that each one of manipulated variables influences only one of the controlled variables (VIGV only the exhaust gas temperature and the fuel mass rate only the load), the transfer functions of two new blocks have been obtained. To compensate for the system non linearity, the calculations are repeated for different load levels. The new control feature can offer advantages in the time response of the regulated plant, especially in the operating range where the airflow can be modulated by the VIGV at constant fuel firing temperature.
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Geoghegan, Patrick, and Vishaldeep Sharma. "Neutron Imaging of a Two-Phase Refrigerant Flow." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52175.
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Void fraction remains a crucial parameter in understanding and characterizing two-phase flow. It appears as a key variable in both heat transfer and pressure drop correlations of two-phase flows, from the macro to micro-channel scale. Void fraction estimation dictates the sizing of both evaporating and condensing phase change heat exchangers, for example. In order to measure void fraction some invasive approach is necessary. Typically, visualization is achieved either downstream of the test section or on top by machining to expose the channel. Both approaches can lead to inaccuracies. The former assumes the flow will not be affected moving from the heat exchanger surface to the transparent section. The latter distorts the heat flow path. Neutron Imaging can provide a non-invasive measurement because metals such as Aluminum are essentially transparent to neutrons. Hence, if a refrigerant is selected that provides suitable neutron attenuation; steady-state void fraction measurements in two-phase flow are attainable in-situ without disturbing the fluid flow or heat flow path. Neutron Imaging has been used in the past to qualitatively describe the flow in heat exchangers in terms of maldistributions without providing void fraction data. This work is distinguished from previous efforts because the heat exchanger has been designed and the refrigerant selected to avail of neutron imaging. This work describes the experimental flow loop that enables a boiling two-phase flow; the heat exchanger test section and downstream transparent section are described. The flow loop controls the degree of subcooling and the refrigerant flowrate. Heating cartridges embedded in the test section are employed to control the heat input. Neutron-imaged steady-state void fraction measurements are captured and compared to representative high-speed videography captured at the visualization section. This allows a qualitative comparison between neutron imaged and traditional techniques. The measurements are also compared to correlations in the literature. Preliminary void fraction images from a macro-channel flow are presented, consisting of 1 channel, 4mm wide, 4mm high and 83.32mm long. Flow regime identification is examined. The experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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Perdichizzi, A., H. Abdeh, G. Barigozzi, M. Henze, and J. Krueckels. "Aero-Thermal Performance of a Nozzle Vane Cascade With a Generic Non Uniform Inlet Flow Condition: Part I — Influence of Non Uniformity Location." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57438.
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In this paper, the modifications induced by the presence of an inlet flow non uniformity on the aerodynamic performance of a nozzle vane cascade are experimentally assessed. Tests were carried out in a six vane linear cascade whose profile is typical of a first stage nozzle guide vane of a modern heavy duty GT. An obstruction was located in the wind tunnel inlet section to produce a non uniform flow upstream of the leading edge plane. The cascade was tested in an atmospheric wind tunnel at an inlet Mach number Ma1 = 0.12, with a high turbulence intensity (Tu1 = 9%) and variable obstruction tangential and axial positions, as well as tangential extension. The presented results show that an inlet flow non uniformity influences the stagnation point position when it faces the vane leading edge from the suction side. A relevant increase of both 2D and secondary losses are observed when the non uniformity is aligned to the vane leading edge. When it is instead located in between the passage it does not affect the stagnation point location, in the meanwhile allowing a reduction in the secondary loss.
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Kim, Tae-Soon, Jae-Gon Lee, Je-Jun Lee, and Myeong-Man Park. "Development of Remote Measuring System for RVI Modularization." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48657.
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The construction duration of a nuclear power plant has been considered as a important factor to occupy the competitive edge. For the optimization process of APR1400 which is nuclear reactor newly developed in Korea, it has been suggested that the modularization of reactor vessel internals (RVI) was one of useful means to reduce the construction duration. In general, RVI consists of three components such as core support barrel (CSB), lower support structure/core shroud (LSS/CS) and upper guide structure (UGS). It is complicated and tedious to assemble the RVI by the conventional method which requires about 8∼10 months. In order to modularize the RVI, the gap between the CSB snubber lug and the reactor vessel (RV) stabilization lug must be measured by a remote measurement method. By using a remote measurement method, the welding of CSB and LSS/CS can be performed in advance of the reactor installation process to reduce the construction duration of a nuclear power plant. Compared with the conventional method, the duration of about 2 months required in the welding of CSB and LSS/CS is finally reduced. In this study, first of all we developed the remote measuring system that included the digital probes to measure the 72 points of gap at once. The system device consists of digital probe section, pneumatic supply and control section, electric power section, remote control computer and program. The selected digital probe of linear variable differential transformer (LVDT) type and the calibration device for the zero-point adjustment jig and the other devices have sufficient reliability and accuracy. And the digital probe connection jig has sufficient consistency. The network and system for remote measurement were very stable and no disturbance at electromagnetic interference environment. And we carried out the proof test of our remote measuring system to evaluate the application on the real plant conditions using the RV and RVI mock-up. The results of remote measurement were compared with existing manual measuring method and the reliability of the system was verified. Finally, we confirmed that our remote measuring system had the efficient reliability could be applied to measure the gap of RVI.
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Spytek, Christopher J. "Application of an Inter-Turbine Burner Using Core Driven Vitiated Air in a Gas Turbine Engine." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69333.
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An Inter-Turbine Burner (ITB) that is capable of increasing the thrust of a gas turbine engine with minimal effect on SFC has been developed. Gas turbine engines using multistage turbine sections have the inherent disadvantage of temperature loss through the turbine section. This occurs when each successive turbine stage extracts energy from the superheated mass airflow stream. The net result is limited energy potential due to the first stage turbine temperature limits. An Inter-Turbine Burner (ITB) is able to utilize constant temperature burning through the turbine section by adding burners between the turbine stages. The resultant engine is suited for missions requiring large amounts of constant or intermittent power extraction. The Spytek ITB incorporates a modified version of an Ultra-Compact Combustor (UCC) [1] (high-g burner) which was originally developed by the Air Force Research Laboratory in Dayton, Ohio. The ITB has been incorporated into a gas turbine engine and has been successfully tested operating at a near constant temperature (NCT) cycle. The engine/ITB is specifically configured and packaged for high power density use. Temperature rises across the ITB (T6-7) were tested in ranges from 421K-588K with representative increases in power take-off noted. The burner, positioned directly upstream of the ITB turbine, operates with vitiated air taken directly from the core engine exhaust stream. The engine tested is a two spool turbo-jet (ITB shaft inclusive), in the 1334(N) class. The ITB is cross shaft linked to an axial compressor booster stage, attached to the engine inlet which super-charged the core engine. The two major areas addressed in development were the ability to provide air into the primary burn zone of the ITB to sustain combustion and second, the ability to successfully entrain the combustion products from the ITB vortex chamber into the main air stream without causing undue restrictions or hot-streak problems which can affect the life of the ITB turbine. Flexibility in ITB testing is further enhanced through the use of two adjustable test features, 1) a variable flow splitter, capable of adjusting the amount of air diverted into the ITB combustor, and 2) a variable nozzle guide vane pack upstream of the ITB turbine. A proprietary entrainment system rapidly mixes the ITB combustor products with the main stream dilute flow products without any undo effects on the ITB turbine. The Mark#1 version of the ITB system exhibits power on demand increases of 16%–22%.
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Almallah, Mustafa Suhail, Qinaat Hussain, Wael K. M. Alhajyaseen, and Tom Brijs. "Improved Road Safety at Work Zones using Advanced Traveler Information Systems." In Qatar University Annual Research Forum & Exhibition. Qatar University Press, 2020. http://dx.doi.org/10.29117/quarfe.2020.0243.
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Work zones are road sections where road construction or maintenance activities take place. These work zones usually have different alignment and furniture than the original road and thus temporary lower speeds are adopted at these locations. However, drivers usually face difficulty in adopting the new speed limit and maneuvering safely due to the change in alignment. Therefore, work zones are commonly considered as hazardous locations with higher crash rates and severities as reported in the literature. This study aims to investigate the effectiveness of a variable message signs (VMSs) based system for work zone advance warning area. The proposed system aims at enhancing driver adaptation of the reduced speed limit, encourage early lane changing maneuvers and improve the cooperative driving behavior in the pre-work zone road section. The study was conducted using a driving simulator at the College of Engineering of Qatar University. Seventy volunteers holding a valid Qatari passenger car driving license participated in this study. In the simulator experiment, we have two scenarios (control and treatment). The control scenario was designed based on the Qatar Work Zone Traffic Management Guide (QWZTMG), where the length of the advance warning area is 1000 m. Meanwhile, the treatment scenario contains six newly designed variable message signs where two of them were animation-based. The VMSs were placed at the same locations of the static signs in the control scenario. Both scenarios were tested for two situations. In the first situation, the participants were asked to drive on the left lane while in the second situation, they were instructed to drive on the second lane. The study results showed that the proposed system was effective in motivating drivers to reduce their traveling speed in advance. Compared to the control scenario, drivers’ mean speed was significantly 6.3 and 11.1 kph lower in the VMS scenario in the first and second situations, respectively. Furthermore, the VMS scenario encouraged early lane changing maneuvers. In the VMS scenario, drivers changed their lanes in advance by 150 m compared to the control scenario. In addition, the proposed system was effective in motivating drivers to keep larger headways with the frontal merging vehicle. Taking into account the results from this study, we recommend the proposed VMS based system as a potentially effective treatment to improve traffic safety at work zones.