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Статті в журналах з теми "Axial extension":
1
Khan, Mahbub H., and G. Charles Clifton. "Proposed development of a damage-resisting Eccentrically Braced Frame with rotational active links." Bulletin of the New Zealand Society for Earthquake Engineering 44, no. 2 (June 30, 2011): 99–107. http://dx.doi.org/10.5459/bnzsee.44.2.99-107.
Анотація:
Eccentrically Braced Frames (EBFs) are widely used seismic-resisting systems, as they allow both strength and stiffness to be optimised while providing good ductility capacity. However, in theory they have a low damage threshold in severe earthquakes and post-earthquake repair of conventional EBFs will be difficult and expensive.
This paper presents the Numerical Integration Time-History (NITH) analysis of two ten storey EBF buildings; one with a conventional active link and the other with a new form of low damage active link based on rotational sliding bolted plates. The low damage active link can be designed to allow rotation only, or to allow both rotation and axial extension. The conventional active link response in terms of displacement, rotation and inelastic demand was well within the range of the rotational active links under the records considered. The analysis shows that average maximum displacement of the building and rotation of the link for both the rotational and the rotational+extension active links was almost identical. The extension of the rotational active link permitting axial extension was less than 1.5 mm. Axial load demands on the collector beams and braces were similar in the case all three active links.
It can be concluded from the analysis that the rotational active link with extension is not required, as the lateral extensions can be accommodated within the rotational plates with nominal clearances in the bolt holes to accommodate the lateral extension.
2
Ghosh, Shantanu, Debabrata Das, Rahul Varshney, and Sumit Nandy. "Orbital extension of trigeminal schwannoma." Journal of Neurosciences in Rural Practice 6, no. 01 (January 2015): 102–4. http://dx.doi.org/10.4103/0976-3147.143214.
Анотація:
ABSTRACTSchwannomas, also known as neurilemmomas, are benign peripheral nerve sheath tumors. Trigeminal schwannomas are rare intracranial tumors. Here, we report a 35-year-old female presenting with an axial proptosis of right eyeball with right-sided III, IV and VI cranial nerve palsy. Her best corrected visual acuity in the right eye was perception of light absent and in the left eye was 20/20. MRI scan revealed a large right-sided heterogeneous, extra-axial middle cranial fossa mass that extended to the intraconal space of right orbit. A diagnosis of intracranial trigeminal nerve schwannoma with right orbital extension was made. Successful surgical excision of the mass with preservation of the surrounding tissues and orbital exenteration was done. Post-operative period was uneventful.
3
Brinkhorst, Michelle, Geert Streekstra, Joost van Rosmalen, Simon Strackee, and Steven Hovius. "Effects of axial load on in vivo scaphoid and lunate kinematics using four-dimensional computed tomography." Journal of Hand Surgery (European Volume) 45, no. 9 (August 3, 2020): 974–80. http://dx.doi.org/10.1177/1753193420943400.
Анотація:
This in vivo study investigated the effect of axial load on lunate and scaphoid kinematics during flexion–extension and radial–ulnar deviation of the uninjured wrist using four-dimensional computed tomography. We found that applying axial load to the wrist results in a more flexed, radially deviated and pronated position of the lunate and scaphoid during flexion–extension of the wrist compared with when no load is applied. A larger pronation and supination range of the lunate and scaphoid was seen when the wrist was flexed and extended under axial load, whereas a larger flexion and extension range of the lunate and scaphoid occurred during radial–ulnar deviation of the wrist when axial load was applied.
4
AMORIM, R., J. BARCELOS-NETO, and A. DE SOUZA DUTRA. "AXIAL-SCHWINGER MODEL." International Journal of Modern Physics A 11, no. 16 (June 30, 1996): 2931–39. http://dx.doi.org/10.1142/s0217751x96001425.
Анотація:
We consider an extension of the axial model where local gauge symmetries are taken into account. The result is a mixing of the axial and Schwinger models. The anomaly of the axial current is calculated by means of the Fujikawa path integral technique and the model is also solved. Besides the well-known features of the particular models (axial and Schwinger) an effective interaction of scalar and gauge fields via a topological current is obtained. This term is responsible for the appearance of massive poles in the propagators that are different from those of both models.
5
Roche, P. H., S. Malca, D. Gambarelli, and W. Pellet. "Giant central neurocytoma with tetraventricular and extra-axial extension." Acta Neurochirurgica 133, no. 1-2 (March 1995): 95–100. http://dx.doi.org/10.1007/bf01404957.
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Paredes, Manuel, Thomas Stephan, and Hervé Orcière. "Enhanced formulae for determining the axial behavior of cylindrical extension springs." Mechanics & Industry 20, no. 6 (2019): 625. http://dx.doi.org/10.1051/meca/2019067.
Анотація:
Cylindrical extension springs have been commonly exploited in mechanical systems for years and their behavior could be considered as well identified. Nevertheless, it appears that the influence of the loops on the global stiffness is not yet taken into account properly. Moreover, it would be of key interest to analyze how initial tension in extension springs influences the beginning of the load-length curve. The paper investigates these topics using analytical, simulation and experimental approaches in order to help engineers design extension springs with greater accuracy. As a result, the stiffness of the loops has been analytically defined. It enables to calculate the global stiffness of extension springs with more accuracy and it is now possible to determine the effective beginning of the linear load-length relation of extension springs and thus to enlarge the operating range commonly defined by standards. Moreover, until now manufacturers had to define by a try and error process the axial pitch of the body of extension springs in order to obtain the required initial tension. Our study enables for the first time to calculate quickly this key parameter saving time on the manufacturing process of extension springs.
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Phuntsok, Rinchen, Marcus D. Mazur, Benjamin J. Ellis, Vijay M. Ravindra, and Douglas L. Brockmeyer. "Development and initial evaluation of a finite element model of the pediatric craniocervical junction." Journal of Neurosurgery: Pediatrics 17, no. 4 (April 2016): 497–503. http://dx.doi.org/10.3171/2015.8.peds15334.
Анотація:
OBJECT There is a significant deficiency in understanding the biomechanics of the pediatric craniocervical junction (CCJ) (occiput–C2), primarily because of a lack of human pediatric cadaveric tissue and the relatively small number of treated patients. To overcome this deficiency, a finite element model (FEM) of the pediatric CCJ was created using pediatric geometry and parameterized adult material properties. The model was evaluated under the physiological range of motion (ROM) for flexion-extension, axial rotation, and lateral bending and under tensile loading. METHODS This research utilizes the FEM method, which is a numerical solution technique for discretizing and analyzing systems. The FEM method has been widely used in the field of biomechanics. A CT scan of a 13-month-old female patient was used to create the 3D geometry and surfaces of the FEM model, and an open-source FEM software suite was used to apply the material properties and boundary and loading conditions and analyze the model. The published adult ligament properties were reduced to 50%, 25%, and 10% of the original stiffness in various iterations of the model, and the resulting ROMs for flexion-extension, axial rotation, and lateral bending were compared. The flexion-extension ROMs and tensile stiffness that were predicted by the model were evaluated using previously published experimental measurements from pediatric cadaveric tissues. RESULTS The model predicted a ROM within 1 standard deviation of the published pediatric ROM data for flexion-extension at 10% of adult ligament stiffness. The model's response in terms of axial tension also coincided well with published experimental tension characterization data. The model behaved relatively stiffer in extension than in flexion. The axial rotation and lateral bending results showed symmetric ROM, but there are currently no published pediatric experimental data available for comparison. The model predicts a relatively stiffer ROM in both axial rotation and lateral bending in comparison with flexion-extension. As expected, the flexion-extension, axial rotation, and lateral bending ROMs increased with the decrease in ligament stiffness. CONCLUSIONS An FEM of the pediatric CCJ was created that accurately predicts flexion-extension ROM and axial force displacement of occiput–C2 when the ligament material properties are reduced to 10% of the published adult ligament properties. This model gives a reasonable prediction of pediatric cervical spine ligament stiffness, the relationship between flexion-extension ROM, and ligament stiffness at the CCJ. The creation of this model using open-source software means that other researchers will be able to use the model as a starting point for research.
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Gao, Bao Kui, Wei Wang, and Xing Qin. "Feasibility Analysis of Reverse Sealed Testing String in HPHT Wells." Applied Mechanics and Materials 556-562 (May 2014): 2761–64. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.2761.
Анотація:
To solve problems met in an offshore High-Pressure High-Temperature (HPHT) well testing, a new technology is put forward—placing seal bore extension above permanent packer, and the upper landing tools being connected with seal bore extension through shear pins. This method gives a reverse position of seal bore extension compared with conventional way in which seal bore extension is below permanent packer. So, the feasibility must be considered. Two technological procedures, testing before cutting pins and testing after cutting pins, are discussed, and the highlight is on axial force and deformation of testing string at crucial moments. Results indicate that this new technology is feasible. Of the two technological procedures, axial force is the key factor when testing before cutting pins and axial deformation is the key factor when testing after cutting pins. Conclusions have been used in an offshore HPHT well testing design.
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Yang, W., T. C. Fung, K. S. Chian, and C. K. Chong. "3D Mechanical Properties of the Layered Esophagus: Experiment and Constitutive Model." Journal of Biomechanical Engineering 128, no. 6 (May 11, 2006): 899–908. http://dx.doi.org/10.1115/1.2354206.
Анотація:
The identification of a three dimensional constitutive model is useful for describing the complex mechanical behavior of a nonlinear and anisotropic biological tissue such as the esophagus. The inflation tests at the fixed axial extension of 1, 1.125, and 1.25 were conducted on the muscle and mucosa layer of a porcine esophagus separately and the pressure-radius-axial force was recorded. The experimental data were fitted with the constitutive model to obtain the structure-related parameters, including the collagen amount and fiber orientation. Results showed that a bilinear strain energy function (SEF) with four parameters could fit the inflation data at an individual extension very well while a six-parameter model had to be used to capture the inflation behaviors at all three extensions simultaneously. It was found that the collagen distribution was axial preferred in both layers and the mucosa contained more collagen, which were in agreement with the findings through a pair of uniaxial tensile test in our previous study. The model was expected to be used for the prediction of stress distribution within the esophageal wall under the physiological state and provide some useful information in the clinical studies of the esophageal diseases.
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Schoeftner, Juergen. "Extension of Castigliano’s method for isotropic beams." Acta Mechanica 231, no. 11 (August 19, 2020): 4621–40. http://dx.doi.org/10.1007/s00707-020-02762-z.
Анотація:
Abstract In the present contribution Castigliano’s theorem is extended to find more accurate results for the deflection curves of beam-type structures. The notion extension in the context of the second Castigliano’s theorem means that all stress components are included for the computation of the complementary strain energy, and not only the dominant axial stress and the shear stress. The derivation shows that the partial derivative of the complementary strain energy with respect to a scalar dummy parameter is equal to the displacement field multiplied by the normalized traction vector caused by the dummy load distribution. Knowing the Airy stress function of an isotropic beam as a function of the bending moment, the normal force, the shear force and the axial and vertical load distributions, higher-order formulae for the deflection curves and the cross section rotation are obtained. The analytical results for statically determinate and indeterminate beams for various load cases are validated by analytical and finite element results. Furthermore, the results of the extended Castigliano theory (ECT) are compared to Bernoulli–Euler and Timoshenko results, which are special cases of ECT, if only the energies caused by the bending moment and the shear force are considered. It is shown that lower-order terms for the vertical deflection exist that yield more accurate results than the Timoshenko theory. Additionally, it is shown that a distributed load is responsible for shrinking or elongation in the axial direction.
Дисертації з теми "Axial extension":
1
Voinier, Steven. "Passive Stiffness Characteristics of the Scoliotic Lumbar Torso in Trunk Flexion, Extension, Lateral bending, and Axial Rotation." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52241.
Анотація:
As the average American age increases, there is a need to study the spine biomechanics of adults with scoliosis. Most studies examining the mechanics of scoliosis have focused on in vitro testing or computer simulations, but in vivo testing of the mechanical response of a scoliotic spine has not yet been reported. The purpose of this study was to quantitatively define the passive stiffness properties of the in vivo scoliotic spine in three principle anatomical motions and identify differences relative to healthy controls.
Scoliotic (n=14) and control (n=17) participants with no history of spondylolisthesis, spinal fracture, or spinal surgery participated in three different tests (torso lateral side bending, torso axial rotation, and torso flexion/extension) that isolated mobility to the in vivo lumbar spine. Scoliotic individuals with Cobb angles ranging 15-75 degrees were accepted. Applied torque was measured using a uni-directional load cell, and inertial measurement units (IMU) recorded angular displacement of the upper torso relative to the pelvis and lower extremities. Torque-rotational displacement data were fit using a double sigmoid function, resulting in excellent overall fit (R2 > 0.901). The neutral zone (NZ) width, or the range of motion where there is minimal internal resistance, was then calculated. Stiffnesses within the NZ and outside of the NZ were also calculated. Stiffness asymmetries were also computed within each trial. These parameters were statistically compared between factor of population and within factor of direction.
There was an interaction effect between populations when comparing axial twist NZ width and lateral bend NZ width. The lateral bend NZ width magnitude was significantly smaller in scoliotic patients. NZ stiffness in the all three directions was greater in the scoliotic population. There was no significant difference in asymmetrical stiffness between populations.
The present study is the first investigation to quantify the in vivo neutral zone and related mechanics of the scoliotic lumbar spine. Future research is needed to determine if the measured lumbar spine mechanical characteristics can help explain progression of scoliosis and complement scoliosis classification systems.Master of Science
2
Al-Itry, Racha. "Mélanges de polymères à base de poly(Acide lactique) : relation structure/rhéologie/procédés de mise en forme." Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00876617.
Анотація:
Ce travail de thèse porte sur l'étude des relations structure/procédés de mise en forme/propriétés finales de matériaux polymères à base de PLA/PBAT. Ces derniers sont destinés à l'emballage alimentaire en vue de remplacer le polyéthylène téréphtalate (PET). Cependant le PLA a certaines limites de processabilité par les technologies de la plasturgie. Le renforcement de ses propriétés à l'état fondu a été obtenu grâce à l'introduction d'un époxyde multifonctionnel capable de réagir avec les bouts de chaînes des polyesters. Aussi, des mélanges à base de PLA/PBAT ont été mis en œuvre en vue de conférer la ductilité au matériau final. La première étape consiste en la compréhension des mécanismes de dégradation thermique et hydrolytique des deux polymères PLA et PBAT au cours des processus de mise en œuvre. En effet, la réaction d'extension des chaînes couplée au branchement induits par l'époxyde multifonctionnel palie cette dégradation. Les mécanismes d'extension de chaînes et de branchements sous-jacents ont été mis en évidence par l'analyse des énergies d'activation, des spectres de relaxation à l'état fondu ainsi que celle des grandeurs physico-chimiques en solution. En outre, les représentations de Van-Gurp-Palmen confirment la co-existence de chaînes macromoléculaires linéaires et aléatoirement branchées. La seconde étape de ce travail a été dédiée à la compatibilisation des mélanges PLA/PBAT par ce même époxyde multifonctionnel. Des études expérimentales modèles basées sur la détermination de la tension interfaciale et la modélisation rhéologique ont montré le rôle majeur de compatibilisant induit par cet agent réactif. Ainsi, la diminution de la tension interfaciale confère à ces matériaux une meilleure cohésion interfaciale et une morphologie fine et homogène de la phase dispersée, accompagnée par l'amélioration des propriétés mécaniques. L'étude des propriétés rhéologiques en cisaillement et en élongation des matériaux modifiés a permis de montrer une meilleure tenue mécanique à l'état fondu. Ainsi, une meilleure aptitude à l'extrusion gonflage a été démontrée en élargissant leurs cartes de stabilité. Parallèlement à ces travaux, des études de bi-étirage des polymères seuls, de leurs homologues modifiés et de leurs mélanges montrent un durcissement structural, dû à la cristallisation induite sous déformation. Les morphologies cristallines ont été analysées finement par des méthodes calorimétriques et spectroscopiques. Enfin, ces études ont été transposées à l'élaboration et à la compréhension des comportements d'une formulation industrielle complexe à base de PLA, PBAT et de farine céréalière plastifiée.
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Zhang, Wang. "Contribution à l'étude expérimentale du comportement mécanique des argilites du Callovo-Oxfordien : effets du chemin de chargement et de la température." Thesis, Université de Lille (2018-2021), 2021. https://pepite-depot.univ-lille.fr/ToutIDP/EDENGSYS/2021/2021LILUN037.pdf.
Анотація:
Les argilites du Callovo-Oxfordien (COx) sont étudiées depuis plusieurs décennies en France dans le contexte du stockage géologique des déchets radioactifs. Un grand nombre d'essais en laboratoire et d'expériences in-situ ont été réalisés pour la caractérisation du comportement thermo-hydromécanique à court et long terme ainsi que des propriétés de diffusion de gaz de cette roche argileuse. Cependant, certains aspects nécessitent encore des études complémentaires, entre autres, les effets du chemin de chargement et de la température sur les réponses mécaniques à court et long terme. Cette thèse apporte une nouvelle contribution aux travaux précédents sur ces aspects encore ouverts. Elle est composée de trois parties.Dans la première partie, l'influence du chemin de chargement sur le comportement mécanique à court terme des argilites du COx est considérée. Sur la base de l'analyse théorique du chemin de la contrainte autour d’une cavité souterraine, deux chemins de chargement particuliers avec deux valeurs différentes de l'angle de Lode sont sélectionnés, à savoir la décompression latérale et l'extension axiale avec une contrainte moyenne constante. Une série d’essais avec différentes valeurs de la contrainte moyenne est réalisée. Des cycles de déchargement-rechargement sont inclus dans les essais. Les résultats obtenus sont analysés et l'accent est mis sur les influences du chemin de chargement (angle de Lode) sur la résistance à la rupture et le processus d'endommagement induit.La deuxième partie est consacrée à l'étude de l'effet thermique sur le comportement mécanique à court terme des argilites du COx. Dans ce but, une série d'essais en laboratoire, avec les deux chemins de chargement (extension axiale et décompression latérale) et différentes valeurs de la température, sont réalisés. Sur la base des résultats obtenus, les effets de la température sur les propriétés élastiques et la résistance à la rupture sont discutés et mis en évidence pour les deux chemins de chargement.Dans la troisième partie, nous nous intéressons à l'effet du chemin de chargement et de la température sur le comportement mécanique à long terme des argilites COx. Une série d’essais de fluage est alors réalisée avec les deux chemins de chargement et différentes valeurs de la température. Les résultats obtenus sont analysés et discutés en mettant l'accent sur les influences du chemin de chargement et de la température sur la cinétique de déformation de fluageCallovo-Oxfordian (COx) claystone has been investigated for several decades in France in the context of geological disposal of radioactive waste. A large number of laboratory tests and in-situ experiments have been conducted for the characterization of short and long thermo-hydromechanical behavior as well as gas flow diffusion property of this clayey rock. However, some aspects still need further investigation, among others, effects of loading paths and temperature on short and long-term mechanical responses. This thesis brings a new contribution to previous works on these open aspects. It is composed of three parts.In the first part, the influence of the loading path on the short-term mechanical behavior of COx claystone is considered. Based on theoretical analysis of stress path around the underground cavity, two particular loading paths with two different values of Lode angle are selected, namely lateral decompression and axial extension under constant mean stress. A series of tests with different values of mean stress are performed. Unloading-reloading cycles are involved in the tests. The obtained results are then analyzed and the emphasis is put on the influences of loading path (Lode angle) on the failure strength and induced damage process.The second part is devoted to studying the thermal effect on the short-term mechanical behavior of COx claystone. For this purpose, a series of laboratory tests, with both loading paths (axial extension and lateral decompression) and different values of temperature are performed. Based on the obtained results, the effects of temperature on the elastic property and failure strength are discussed for the two loading paths.In the third part, we are interested in investigating the effect of loading paths and temperature on the long-term mechanical behavior of COx claystone. A series of creep tests are then performed under two loading paths and with different values of temperature. The obtained test results are analyzed and discussed by putting the emphasis on the influences of loading path and temperature on creep deformation kinetics
4
Wei, Chao-Yung, and 魏釗勇. "Endochronic Simulation on the stability of Thick-Walled Tubes subjected to External Pressure and Axial Extension." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/02409440881912205260.
Анотація:
碩士國立成功大學
工程科學系
86
The paper presents the results from a combined experimental and analyticstudy on the collapse of long, thick-walled tubes subjected to externalpressure and axial tension. The experiments tubes of diameter-to-thicknessratio (Dm/t) 10 to 40. Collapse envelopes were obtained for two different pressure tension loading paths.
5
Lin, Jian-Hung, and 林建宏. "Study on the Axial Extension Mechanical Property of Soils Between Jet Grouted Soil Column After Lateral Compression." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/29628652844972876056.
Анотація:
碩士國立臺灣科技大學
營建工程系
89
Soils between grouted soil column are subjected to lateral compression during the grouting process. Because jet grouting proceeds in sequence, the grouting pressure is often not symmetrical. The ungrouted soils are then subjected to axial extension in subsequent excavation stage.As a result, the construction factors may influence the mechanical property of the ungrouted soil. In general, designers should consider the above factors. A series of triaxial stress path test were performed on undisturbed Taipei silty clay and true triaxial test were performed on remoulded Taipei silty clay in order to understand the ungrouted soil’s mechanical property of axial extension after jet grouting. Results from three triaxial test indicate that（1）the influence of jet grouting on the undrained axial extension behavior is very little.（2） the available undrained strength may be reduced in the process of jet grouting.（3）the deformation modulus decreases with increasing amount of lateral compression, but increases with lateral extension. Results from true triaxial test indicate that（1）one-way lateral compression has little influence on the axial extension behavior, two way compression may reduce undrained shear strength.；（2）for different types of lateral compression, with the same compression magnitude, the excited excess pore pressure may exhibit different behavior depending on the amount of lateral compression.
Книги з теми "Axial extension":
1
Baraliakos, Xenofon, and Kay-Geert A. Hermann. Imaging: spine. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780198734444.003.0014.
Анотація:
Although axial spondyloarthritis (axSpA) starts in the sacroiliac joints in the vast majority of cases, the spine can be clinically affected with similar severity and frequency, especially in long-standing disease. In addition, not only the inflammatory but also structural changes seen in the sacroiliac joints can be visualized in the same way in the spine when using the appropriate imaging techniques. For the interpretation of imaging findings in axSpA, typical and frequent differential diagnoses need to be taken into account, such as degenerative changes, bacterial inflammation, and fractures, and also non-pathological findings such as haemangioma. This chapter concentrates on the imaging of the spine in axSpA, giving an extensive overview of the relevant diagnostic and differential diagnostic findings in patients with axSpA and the most common differential diagnoses.
2
Kaeley, Gurjit S. Use of ultrasound in psoriatic arthritis. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780198737582.003.0017.
Анотація:
Psoriatic arthritis (PsA) is much more than just joint disease. Although previous clinical classifications have categorized by pattern of joint involvement and axial disease, imaging techniques such as MRI and ultrasound have demonstrated that not only are many more joints involved but also a wide variety of adjoining tissues. The concept of enthesitis is evolving and high resolution imaging studies are demonstrating involvement of tissues beyond just the enthesis. Many investigators have chosen to use sonographic entheseal systems designed for Spondyloarthritis in general which may not be appropriate and may lead to excess confounding by obesity. Inclusion of entheses that seem more relevant to PsA may improve the validity and specificity of the sonographic outcome tool. Nail affliction is associated with PsA, as well as enthesitis. Sonography is able to demonstrate the nail apparatus. More recent pathoanatomic findings may help explain the close link with enthesitis. Synovitis in PsA is often involved with inflammation and alteration of neighbouring structures such as the extensor tendons, palmar or plantar plates. Some investigators have proposed that inflammation in PsA may start at the entheseal sites and then spread to the joint. Dactylitis epitomizes the concept of multiple tissues involved in the digit giving rise to the clinical appearance of a uniformly swollen digit. Sonography can image many of these tissues in high resolution and offer insights into the pathophysiology of dactylitis.
Частини книг з теми "Axial extension":
1
Pipes, R. Byron, and N. J. Pagano. "Interlaminar Stresses in Composite Laminates Under Uniform Axial Extension." In Solid Mechanics and Its Applications, 234–45. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-017-2233-9_19.
2
Paredes, Manuel, Thomas Stephan, and Hervé Orcière. "Experimental and Analytical Approaches for Determining the Axial Behavior of Cylindrical Extension Springs." In Lecture Notes in Mechanical Engineering, 275–83. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-41200-5_30.
3
Zahorski, Stefan. "Fibre Spinning with Axial and Radial Viscosity Distributions as Viscoelastic Flow with Dominating Extension." In Third European Rheology Conference and Golden Jubilee Meeting of the British Society of Rheology, 525–27. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0781-2_178.
4
Ascani, E., G. C. Giglio, M. Crostelli, and E. Gasbarra. "Biomechanical Problems, Axial Deviation and Functional Recovery in Extensive Limb Lengthening." In Human Achondroplasia, 373–80. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4684-8712-1_48.
5
Wan, Frederic Y. M. "Finite Axial Extension and Torsion of Elastic Helicoidal Shells." In Asymptotic and Computational Analysis, 491–516. CRC Press, 2020. http://dx.doi.org/10.1201/9781003072584-24.
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Lee, Christine U., and James F. Glockner. "Case 13.5." In Mayo Clinic Body MRI Case Review, edited by Christine U. Lee and James F. Glockner, 623–24. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199915705.003.0329.
Анотація:
72-year-old woman with a nonproductive cough and a mass on chest radiograph Axial (Figure 13.5.1) and sagittal (Figure 13.5.2) fat-suppressed FSE T2-weighted images reveal a large centrally necrotic mass in the posterior left lower lobe. Notice the subtle tail of soft tissue extending across the pleura with minimal extension into the chest wall. Axial postgadolinium 3D SPGR images (...
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Lee, Christine U., and James F. Glockner. "Case 2.16." In Mayo Clinic Body MRI Case Review, edited by Christine U. Lee and James F. Glockner, 92–93. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199915705.003.0047.
Анотація:
83-year-old man being evaluated in the emergency department for abdominal pain Axial postgadolinium portal venous phase images (Figure 2.16.1) demonstrate nearly occlusive thrombus throughout the main portal vein. Reformatted oblique images (Figure 2.16.2) show thrombus extension into the right and left portal veins and the superior mesenteric vein....
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Lee, Christine U., and James F. Glockner. "Case 12.9." In Mayo Clinic Body MRI Case Review, edited by Christine U. Lee and James F. Glockner, 581–82. Oxford University Press, 2014. http://dx.doi.org/10.1093/med/9780199915705.003.0307.
Анотація:
34-year-old man with dysuria and urinary frequency Axial (Figure 12.9.1) and coronal (Figure 12.9.2) fat-suppressed FSE T2-weighted images reveal a hypointense infiltrative mass surrounding the bulbous and penile urethra. Coronal postgadolinium 2D SPGR images (Figure 12.9.3) show heterogeneous enhancement of the lesion and irregular margins. Notice on both T2-weighted and postgadolinium coronal images disruption of the normal low-signal-intensity rim of the tunica albuginea with extension into the corpora cavernosa....
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Roy, Apurba Kumar, Supriyo Roy, and Kaushik Kumar. "Strategic Designing and Optimization of Mixed Flow Impeller Blades for Maritime Applications." In Handbook of Research on Military, Aeronautical, and Maritime Logistics and Operations, 470–508. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-9779-9.ch025.
Анотація:
Mixed flow impellers are extensively used in turbomachines either to convert mechanical energy to fluid energy or to convert fluid energy to mechanical energy. According to the geometry of flow passage, turbo machines can be classified as radial, axial and mixed flow. Mixed flow turbomachines are widely used for engineering applications like cooling water duties, water intake impellers for maritime applications, flood water draining, irrigation and other application fields. The design of mixed flow impellers of high specific speed is a direct extension of the well-established methods of the designing of radial flow impellers but the introduction of near diagonal flow layout at a still larger specific speed stimulated the incorporation of axial impeller design techniques in mixed flow impeller technology. Here, an attempt has been made to design a mixed flow turbo machine blade from the basic principle of turbomachinery and fluid mechanics. On the basis of stress analysis, the blade positioning in the meridional annulus was selected and validated using artificial neural network.
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Jain, Pushpdant, and Mohammed Rajik Khan. "Biomechanical Study of Lumbar Spine (L2-L4) Using Hybrid Stabilization Device - A Finite Element Analysis." In Research Anthology on Emerging Technologies and Ethical Implications in Human Enhancement, 339–51. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8050-9.ch016.
Анотація:
Spinal instrumentations have been designed to alleviate lower back pain and stabilize the spinal segments. The present work aims to evaluate the biomechanical effect of the proposed Hybrid Stabilization Device (HSD). Non-linear finite element model of lumbar segment L2-L4 were developed to compare the intact spine (IS) with rigid implant (RI) and hybrid stabilization device. To restrict all directional motion vertebra L4 bottom surface were kept fixed and axial compressive force of 500N with a moment of 10Nm were applied to the top surface of L2 vertebrae. The results of range of motion (ROM), intervertebral disc (IVD) pressure and strains for IVD-23 and IVD-34 were determined for flexion, extension, lateral bending and axial twist. Results demonstrated that ROM of HSD model is higher than RI and lower as compared to IS model. The predicted biomechanical parameters of the present work may be considered before clinical implementations of any implants.
Тези доповідей конференцій з теми "Axial extension":
1
Hirschmann, A., S. Volkmer, M. Casey, and M. Montgomery. "Hub Extension in an Axial Gas Turbine Diffuser." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68832.
Анотація:
Diffusers downstream of axial gas turbines typically support a hub carrying the turbine rotor bearing. The blunt end of the hub is one of the main causes of loss production. However, a long hub can theoretically reduce the losses and improve the pressure recovery of the diffuser and thus the overall performance of the gas turbine. At the end of the hub the flow experiences a sudden expansion, which can be described by the Borda Carnot equation for incompressible fluid. The pressure loss at the end of the hub depends on the dynamic head and the area ratio of the expansion. With a long hub the blunt end moves further downstream into the diffuser and therefore the flow velocity and the area ratio of the step are reduced, resulting in a lower pressure loss. Two different casing geometries, each with a short and a long hub configuration are examined experimentally and numerically using CFD (Computational Fluid Dynamics). The geometrical configurations lead to a separation at the casing for a uniform total pressure profile at the inlet which shows the highly loaded state of the diffuser configuration. Experiments have been conducted at a high subsonic inlet Mach number comparable to real turbine exit flows and a low Mach number representing incompressible flow. It is shown that in some cases the long hub has a benefit to pressure recovery. However, the Mach number at the inlet of the diffuser influences the intensity of this effect. A high inlet Mach number increases the losses in the inlet section of the diffuser and at the struts supporting the hub and hence decreases the diffuser performance. Consequently the performance depending on the particular diffuser design can be decreased with an extended hub configuration.
2
Patel, Ankit Bhai, K. Viswanath, and Dhyanjyoti Deb Nath. "Effect of Axial Sweep and Tip Extension on Performance of an Axial Fan." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65967.
Анотація:
Performance enhancement in terms of stall margin increment, increased pressure rise coefficient and increased efficiency is of great need for low speed axial fans. Stacking line modifications in terms of sweep, skew, dihedral or combination of these, as well as blade tip geometry modifications are assumed to be one of the ways to achieve finite performance improvement. Non radial stacking of blade profiles modifies secondary flows, tip vortex effects, hub passage vortex and thus affects aerodynamic performance parameters such as stall margin, efficiency, pressure rise, blade loading. In literature many studies have confined to comparison of few cases which led to conflicting results as modification of stacking line may have different effects in different cases. In the present work, comparison of performance of axial fan rotor with three different blade configurations BSL (baseline), SWP (swept blade) and EXTN (swept blade with extended tip) are considered. The BSL configuration is designed on basis of non-free vortex design. The SWP configuration is obtained by shifting radial stacking line of the BSL in axial flow direction by 10° (Forward sweep). The EXTN configuration is obtained by extending tip profile on pressure surface as well as suction surface by 3% locally. Experiments have been conducted on these three configurations to study effects of these modifications on aerodynamic performance. The flow field has been surveyed using Kiel probe, Three hole pressure probe at many flow rates starting from fully open to fully closed. Unsteady flow analysis at exit of rotors of all configurations is carried out using fast response pressure probe. Experimental results show slight performance improvement in terms of increased stall margin, efficiency, as well as total pressure rise for SWP rotor as well as EXTN rotor compared to BSL rotor at low flow coefficients.
3
Muthu, S. Esakki, A. Selwyn, Hardik Roy, and Girish K. Degaonkar. "Life Extension of Axial Compressor Disc of a Turbo-Shaft Engine." In ASME 2013 Gas Turbine India Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gtindia2013-3645.
Анотація:
The cost of aero engine and its maintenance is going higher day by day, the life of the critical parts and its availability play a major role to keep the fleet in operation. Engine components works under extremely high stress levels so the life of the components is limited. Most of the critical components are retired by the operator before they reach their theoretical life. The uncertainty in accurate life prediction induces the risk which is the cause for premature retirement. Metallurgical study of the life expired components and fatigue/fracture methodologies are used to estimate the residual useful life of the components. This paper describes the life extension methodology used for an axial compressor disc of turbo-shaft engine. The disc has completed its safe life in the aircraft. The studies are carried out to determine the residual life of the disc to extend the life. Two life completed disc are identified. Specimens are cut from the disc for tensile test and LCF tests. Probable mission cycles for the aircraft are collected and fatigue cycle data are prepared. Finite element based stress analysis is carried out using Ansys software with multi axial loads. Based on the stress analysis, disc bore and pin hole are identified as critical area. The computed stress–strain response is used to predict the fatigue crack initiation life using effective strain range parameters on the critical areas. Fatigue damage for different mission cycles are also calculated using critical plane approach. The plane where crack initiate is called critical plane and it is calculated iteratively based on the nodal stress result. Life for different mission cycle is calculated and minimum life of all the cycle is determined. This calculated life gives the amount of residual life available and the scope for life extension. The disc is tested in cyclic spin test rig to confirm the remaining potential life. The test results are compared with the numerical estimation. It is found that the residual life of the life completed component has got potential life of one more overhaul.
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Yamazaki, S., Y. Tanise, Y. Yamada, and T. Nakamura. "Development of axial extension actuator for narrow pipe inspection endoscopic robot." In 2016 IEEE/SICE International Symposium on System Integration (SII). IEEE, 2016. http://dx.doi.org/10.1109/sii.2016.7844070.
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Dey, Debashis, and Cengiz Camci. "Aerodynamic Tip Desensitization of an Axial Turbine Rotor Using Tip Platform Extensions." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0484.
Анотація:
Aerodynamic losses due to the formation of a leakage vortex near the tip section of rotor blades form a significant part of viscous losses in axial flow turbines. The leakage flow, mainly induced by the pressure differential between the pressure side and suction side of a rotor tip section, usually rolls into a streamwise vortical structure near the suction side part of the blade tip. The current study uses the concept of a tip platform extension that is a very short “winglet” obtained by slightly extending the tip platform in the tangential direction. The use of a pressure side tip extension can significantly affect the local aerodynamic field by weakening the leakage vortex structure. Phase averaged, time accurate total pressure measurements downstream of a single stage turbine facility are provided from a total pressure probe that has a time response of 150 kHz. Complete total pressure maps in all of the 29 rotor exit planes are measured accurately. Various pressure and suction side extension configurations are compared against a baseline case. The current investigation performed in the Axial Flow Turbine Research Facility (AFTRF) of the Pennsylvania State University shows that significant total to total efficiency gain is possible by the use of tip platform extensions.
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Zamyatin, Alexander A., Daxin Shi, and Mihail Petru Dinu. "Extension of axial coverage and artifact reduction in iterative reconstruction in computed tomography." In 2011 IEEE Nuclear Science Symposium and Medical Imaging Conference (2011 NSS/MIC). IEEE, 2011. http://dx.doi.org/10.1109/nssmic.2011.6153790.
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Akturk, Ali, and Cengiz Camci. "Development of a Tip Leakage Control Device for an Axial Flow Fan." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50785.
Анотація:
Performance of an axial fan unit used in ducted fan based propulsion systems is closely related to its tip leakage mass flow rate and the level of tip/casing interactions. The present experimental study uses a stereoscopic Particle Image Velocimeter to quantify the three dimensional mean flow observed at just downstream of a ducted fan unit. After a comprehensive description of the baseline fan exit flow, a number of novel tip treatments based on pressure side extensions are introduced. Various tip leakage mitigation schemes are introduced by varying the chordwise location and the width of the extension in the circumferential direction. The current study shows that a proper selection of the pressure side bump location and width are the two critical parameters influencing the success of each tip leakage mitigation approach. Significant gains in axial mean velocity component are observed when a proper pressure side tip extension is used. It is also observed that a proper tip leakage mitigation scheme significantly reduces the tangential velocity component near the tip of the axial fan blade. Reduced tip clearance interactions are essential in improving the energy efficiency of ducted fan systems. A reduction or elimination of the momentum deficit in tip vortices are also expected to reduce the adverse performance effects originating from the unsteady and highly turbulent tip leakage vortical flows rotating against a stationary casing.
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Nagel, Tina M., Mikhail Golman, David J. Nuckley, and Victor H. Barocas. "Human Annulus Fibrosus Lamellae Generate Significant Multi-Axial Forces and Moments in Biaxial Extension." In ASME 2013 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/sbc2013-14188.
Анотація:
Low back pain is a widespread public health issue affecting about 75% of Americans in their lifetime [1]. In many individuals, the origin remains unknown in spite of decades of research. However, intervertebral disc (IVD) degeneration has been theorized as a major precursor to nonspecific low back pain [2,3].
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Yao, Yanping, Ming-Wan Lu, and Xiong Zhang. "Inelastic Behavior of Pipe Subjected to Steady Extension and Cyclic Bending." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-55239.
Анотація:
The inelastic behavior of a pipe subjected to steady axial force and cyclic bending moment, such as shakedown, plastic fatigue, ratcheting and plastic collapse, is studied. By using two parameters c and d, which indicate the elasto-plastic interfaces of beam cross section, the boundary curve equations between various types of inelastic behavior are derived. The results are suitable for beams of any shaped cross section with two orthogonal symmetric axes. Especially, the load regime diagram for a pipe is obtained, which indicates the elasto-plastic behavior of the pipe under given combination of axial load and cyclic bending moment intuitively.
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Abraham, P. M., and S. E. Wilson. "Effects of a Lumbar Belt on Neuromotor Transmission of Whole Body Vibration." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42358.
Анотація:
Whole body vibration (WBV) has been identified as a risk factor for low back musculoskeletal disorders and injuries. One potential mechanism by which WBV may lead to low back injury is through stimulation of muscle spindle organs and repetitive activation of the stretch-reflex neuromotor response. Such repetitive activation could lead to muscular fatigue and/or neuromotor adaptation. Understanding mechanical transmission of vibration to the neuromotor system and the resulting neuromotor activation is critical to understanding these mechanisms. In this study, it was theorized that activation of the extensor musculature of the low back is a response to the lengthening and shortening of the extensor musculature. This lengthening and shortening of the extensor musculature may be the result of flexion-extension rotation in the lumbar spine. By measuring lumbar flexion and extension, the amplitude and phase of this lengthening and shortening were assessed. Using electromyographic data from the erector spinae muscle groups at the L2/L3 lumbar level, the cyclic activation of the extensor musculature was also measured. Neuromotor transmission was observed over a frequency range of 3–20 Hz and vibration magnitudes of 1 and 2 m/s^2 RMS. Resonance peaks in lumbar flexion-extension and the integrated electromyographic data were observed at 4 Hz and 10–12 Hz. A lumbar belt was used to reduce transmission of axial seat-pan vibration to lumbar flexion-extension and to observe the changes in cyclic electromyographic activity. The lumbar belt was found to decrease both lumbar flexion-extension and paraspinal muscle activity demonstrating a link between axial seatpan vibration, lumbar flexion-extension and the cyclic activation of the neuromotor system. These results provide information on the neuromotor effects of WBV and may be used to design better low back injury prevention methods.
Звіти організацій з теми "Axial extension":
1
Gamble, K. A. Axial Relocation Model Extension in Bison. Office of Scientific and Technical Information (OSTI), August 2018. http://dx.doi.org/10.2172/1605203.