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Добірка наукової літератури з теми "Struts (Engineering) Dynamics"

Автор: Grafiati

Опубліковано: 10 грудня 2022

Оновлено: 30 січня 2023

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Статті в журналах з теми "Struts (Engineering) Dynamics"

He, Yong, Nandini Duraiswamy, Andreas O. Frank, and James E. Moore. "Blood Flow in Stented Arteries: A Parametric Comparison of Strut Design Patterns in Three Dimensions." Journal of Biomechanical Engineering 127, no. 4 (February 10, 2005): 637–47. http://dx.doi.org/10.1115/1.1934122.

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Background: Restenosis after stent implantation varies with stent design. Alterations in secondary flow patterns and wall shear stress (WSS) can modulate intimal hyperplasia via their effects on platelet and inflammatory cell transport toward the wall, as well as direct effects on the endothelium. Method of Approach: Detailed flow characteristics were compared by estimating the WSS in the near-strut region of realistic stent designs using three-dimensional computational fluid dynamics (CFD), under pulsatile high and low flow conditions. The stent geometry employed was characterized by three geometric parameters (axial strut pitch, strut amplitude, and radius of curvature), and by the presence or lack of the longitudinal connector. Results: Stagnation regions were localized around stent struts. The regions of low WSS are larger distal to the strut. Under low flow conditions, the percentage restoration of mean axial WSS between struts was lower than that for the high flow by 10–12%. The largest mean transverse shear stresses were 30–50% of the largest mean axial shear stresses. The percentage restoration in WSS in the models without the longitudinal connector was as much as 11% larger than with the connector. The mean axial WSS restoration between the struts was larger for the stent model with larger interstrut spacing. Conclusion: The results indicate that stent design is crucial in determining the fluid mechanical environment in an artery. The sensitivity of flow characteristics to strut configuration could be partially responsible for the dependence of restenosis on stent design. From a fluid dynamics point of view, interstrut spacing should be larger in order to restore the disturbed flow; struts should be oriented to the flow direction in order to reduce the area of flow recirculation. Longitudinal connectors should be used only as necessary, and should be parallel to the axis. These results could guide future stent designs toward reducing restenosis.

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Aihara, Aya, Victor Mendoza, Anders Goude, and Hans Bernhoff. "Comparison of Three-Dimensional Numerical Methods for Modeling of Strut Effect on the Performance of a Vertical Axis Wind Turbine." Energies 15, no. 7 (March 24, 2022): 2361. http://dx.doi.org/10.3390/en15072361.

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This paper compares three different numerical models to evaluate their accuracy for predicting the performance of an H-rotor vertical-axis wind turbine (VAWT) considering the influence of struts. The strut of VAWTs is one factor that makes the flow feature around the turbine more complex and thus influences the rotor performance. The focus of this study is placed on analyzing how accurately three different numerical approaches are able to reproduce the force distribution and the resulting power, taking the strut effect into account. For the 12 kW straight-bladed VAWT, the blade force is simulated at three tip speed ratios by the full computational fluid dynamics (CFD) model based on the Reynolds-averaged Navier–Stokes (RANS) equations, the actuator line model (ALM), and the vortex model. The results show that all the models do not indicate a significant influence of the struts in the total force over one revolution at low tip speed ratio. However, at middle and high tip speed ratio, the RANS model reproduces the significant decrease of the total tangential force that is caused due to the strut. Additionally, the RANS and vortex models present a clear influence of the struts in the force distribution along the blade at all three tip speed ratios investigated. The prediction by the ALM does not show such distinctive features of the strut impact. The RANS model is superior to the other two models for predicting the power coefficient considering the strut effect, especially at high tip speed ratio.

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Yin, Yuming, Subhash Rakheja, Jue Yang, and Paul-Emile Boileau. "Design optimization of an articulated frame steering system." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 10 (November 11, 2017): 1339–52. http://dx.doi.org/10.1177/0954407017729052.

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The articulated frame-steered vehicles (AFSV) exhibit enhanced maneuverability but reduced yaw stability and greater steering power consumption. Apart from kinematics of the steering system, the dynamics of the actuating system strongly influence the performance of the AFSV, which is generally neglected in the reported studies. In this study, a yaw-plane model of the articulated vehicle coupled with the kinematic and dynamics properties of the steering struts is formulated to identify objective measures of the AFSV under steering inputs. The results suggest that the vehicle yaw oscillation/stability, steering power efficiency and maneuverability can be objectively measured in terms of the strut length, yaw oscillation frequency and damping ratio, steering gain, and steering response rate and overshoot. The layout of steering struts and properties of the steering valve and hydraulic fluid are optimized while employing the weighted-sum method and a combination of pattern search and sequential quadratic programming algorithms. The relative weights of individual performance measures were obtained using the analytic hierarchy process (AHP) model. The solutions of the optimization problem revealed more compact articulated frame steering (AFS) system design with over 20% reduction in strut length and 24% gain in the yaw oscillation frequency. Increasing the fluid bulk modulus resulted in more compact AFS layout and further increase in the yaw oscillation frequency with lower response overshoot. The optimal design based on weighted sum of various performance measures, however, revealed negligible changes in terms of the steering power efficiency.

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Jiménez, Juan M., Varesh Prasad, Michael D. Yu, Christopher P. Kampmeyer, Abdul-Hadi Kaakour, Pei-Jiang Wang, Sean F. Maloney, et al. "Macro- and microscale variables regulate stent haemodynamics, fibrin deposition and thrombomodulin expression." Journal of The Royal Society Interface 11, no. 94 (May 6, 2014): 20131079. http://dx.doi.org/10.1098/rsif.2013.1079.

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Drug eluting stents are associated with late stent thrombosis (LST), delayed healing and prolonged exposure of stent struts to blood flow. Using macroscale disturbed and undisturbed fluid flow waveforms, we numerically and experimentally determined the effects of microscale model strut geometries upon the generation of prothrombotic conditions that are mediated by flow perturbations. Rectangular cross-sectional stent strut geometries of varying heights and corresponding streamlined versions were studied in the presence of disturbed and undisturbed bulk fluid flow. Numerical simulations and particle flow visualization experiments demonstrated that the interaction of bulk fluid flow and stent struts regulated the generation, size and dynamics of the peristrut flow recirculation zones. In the absence of endothelial cells, deposition of thrombin-generated fibrin occurred primarily in the recirculation zones. When endothelium was present, peristrut expression of anticoagulant thrombomodulin (TM) was dependent on strut height and geometry. Thinner and streamlined strut geometries reduced peristrut flow recirculation zones decreasing prothrombotic fibrin deposition and increasing endothelial anticoagulant TM expression. The studies define physical and functional consequences of macro- and microscale variables that relate to thrombogenicity associated with the most current stent designs, and particularly to LST.

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Virgin, L. N. "Postbuckling dynamics of struts as related to their loading devices." Engineering Structures 8, no. 2 (April 1986): 127–33. http://dx.doi.org/10.1016/0141-0296(86)90028-3.

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Cheon, Gill-Jeong, and K. B. Chandran. "Transient Behavior Analysis of a Mechanical Monoleaflet Heart Valve Prosthesis in the Closing Phase." Journal of Biomechanical Engineering 116, no. 4 (November 1, 1994): 452–59. http://dx.doi.org/10.1115/1.2895796.

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In this paper, an analysis of the dynamics in the closing phase of the occluder of a mechanical monoleaflet heart valve prosthesis is presented. The dynamic analysis of the fluid in the vicinity of the occluder was based on the control volume approach. The backflow velocity of the fluid was computed by applying the continuity and momentum equations in the unsteady state. By considering the fluid pressure and gravity as external forces acting on the occluder, the moment equilibrium on the occluder was employed to analyze the motion of the occluder during closing and the force of impact between the occluder and the guiding struts. The computed magnitudes of the occluder tip velocities, as well as the backflow of the fluid during the closing phase using this model, were in agreement with previously reported experimental measurements. The maximum impact force between the occluder and guiding struts of 140–280 N was determined to occur during the initial impact for a duration of 35–45 μus. The results of such model studies may be extended for the analysis of the endurance limit of the valve prostheses as well as to determine the mechanical stresses on the formed elements and the incipience of cavitation bubbles during the closing phase of the valve function.

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Chiastra, Claudio, Stefano Morlacchi, Diego Gallo, Umberto Morbiducci, Rubén Cárdenes, Ignacio Larrabide, and Francesco Migliavacca. "Computational fluid dynamic simulations of image-based stented coronary bifurcation models." Journal of The Royal Society Interface 10, no. 84 (July 6, 2013): 20130193. http://dx.doi.org/10.1098/rsif.2013.0193.

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One of the relevant phenomenon associated with in-stent restenosis in coronary arteries is an altered haemodynamics in the stented region. Computational fluid dynamics (CFD) offers the possibility to investigate the haemodynamics at a level of detail not always accessible within experimental techniques. CFD can quantify and correlate the local haemodynamics structures which might lead to in-stent restenosis. The aim of this work is to study the fluid dynamics of realistic stented coronary artery models which replicate the complete clinical procedure of stent implantation. Two cases of pathologic left anterior descending coronary arteries with their bifurcations are reconstructed from computed tomography angiography and conventional coronary angiography images. Results of wall shear stress and relative residence time show that the wall regions more prone to the risk of restenosis are located next to stent struts, to the bifurcations and to the stent overlapping zone for both investigated cases. Considering a bulk flow analysis, helical flow structures are generated by the curvature of the zone upstream from the stent and by the bifurcation regions. Helical recirculating microstructures are also visible downstream from the stent struts. This study demonstrates the feasibility to virtually investigate the haemodynamics of patient-specific coronary bifurcation geometries.

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Manavi, Tejaswini, Masooma Ijaz, Helen O’Grady, Michael Nagy, Jerson Martina, Ciaran Finucane, Faisal Sharif, and Haroon Zafar. "Design and Haemodynamic Analysis of a Novel Anchoring System for Central Venous Pressure Measurement." Sensors 22, no. 21 (November 6, 2022): 8552. http://dx.doi.org/10.3390/s22218552.

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Background/Objective: In recent years, treatment of heart failure patients has proved to benefit from implantation of pressure sensors in the pulmonary artery (PA). While longitudinal measurement of PA pressure profoundly improves a clinician’s ability to manage HF, the full potential of central venous pressure as a clinical tool has yet to be unlocked. Central venous pressure serves as a surrogate for the right atrial pressure, and thus could potentially predict a wider range of heart failure conditions. However, it is unclear if current sensor anchoring methods, designed for the PA, are suitable to hold pressure sensors safely in the inferior vena cava. The purpose of this study was to design an anchoring system for accurate apposition in inferior vena cava and evaluate whether it is a potential site for central venous pressure measurement. Materials and Methods: A location inferior to the renal veins was selected as an optimal site based on a CT scan analysis. Three anchor designs, a 10-strut anchor, and 5-struts with and without loops, were tested on a custom-made silicone bench model of Vena Cava targeting the infra-renal vena cava. The model was connected to a pulsatile pump system and a heated water bath that constituted an in-vitro simulation unit. Delivery of the inferior vena cava implant was accomplished using a preloaded introducer and a dilator as a push rod to deploy the device at the target area. The anchors were subjected to manual compression tests to evaluate their stability against dislodgement. Computational Fluid Dynamics (CFD) analysis was completed to characterize blood flow in the anchor’s environment using pressure-based transient solver. Any potential recirculation zones or disturbances in the blood flow caused by the struts were identified. Results: We demonstrated successful anchorage and deployment of the 10-strut anchor in the Vena Cava bench model. The 10-strut anchor remained stable during several compression attempts as compared with the other two 5-strut anchor designs. The 10-strut design provided the maximum number of contact points with the vessel in a circular layout and was less susceptible to movement or dislodgement during compression tests. Furthermore, the CFD simulation provided haemodynamic analysis of the optimum 10-strut anchor design. Conclusions: This study successfully demonstrated the design and deployment of an inferior vena cava anchoring system in a bench test model. The 10-strut anchor is an optimal design as compared with the two other 5-strut designs; however, substantial in-vivo experiments are required to validate the safety and accuracy of such implants. The CFD simulation enabled better understanding of the haemodynamic parameters and any disturbances in the blood flow due to the presence of the anchor. The ability to place a sensor technology in the vena cava could provide a simple and minimally invasive approach for heart failure patients.

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Yin, Yuming, Subhash Rakheja, Jue Yang, and Paul-Emile Boileau. "Effect of articulated frame steering on the transient yaw responses of the vehicle." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 3 (June 16, 2017): 384–99. http://dx.doi.org/10.1177/0954407017702987.

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The directional performance characteristics of articulated frame steering vehicles are known to be strongly coupled with the kinematic characteristics and the dynamic characteristics of the steering system. The reported studies on articulated frame steering generally focus on the yaw divergence behaviour or the snaking tendency of the vehicle based on its free-yaw-oscillation response, while neglecting important contributions due to the kinematics and the dynamics of the steering system. This study characterizes both the free-yaw-oscillation response and the transient steering response of an articulated frame steering mining vehicle, considering the kinematics of the steering struts together with the dynamics of the flow volume-regulated steering valve and the actuating system. The validity of the analytical vehicle and steering system model is demonstrated using the measured data acquired for the vehicle. The free-oscillation behaviour of the articulated frame steering is characterized in terms of the yaw-mode natural frequency and the yaw damping ratio. The transient responses of the articulated frame steering are assessed in terms of the steering gain, the rate of articulation and the articulation overshoot. The effects of the variations in the various articulated frame steering parameters on the free response and the transient response are subsequently investigated and discussed so as to seek guidance for the design of the articulated frame steering system. It is shown that a higher bulk modulus of the hydraulic fluid and longer steering-arm lengths yield a higher yaw stiffness of the articulated frame steering system and thereby a higher frequency of the yaw oscillations. Higher leakage flows and higher viscous seal friction cause a higher yaw damping coefficient but decrease the steering gain and the articulation rate of the vehicle.

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Boudet, J., V. N. D. Autef, J. W. Chew, N. J. Hills, and O. Gentilhomme. "Numerical simulation of rim seal flows in axial turbines." Aeronautical Journal 109, no. 1098 (August 2005): 373–83. http://dx.doi.org/10.1017/s000192400070042x.

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AbstractIn a gas turbine, ingestion of hot gas into the high-pressure turbine disc cavities could cause metal overheat. To prevent this, cool air is taken from the compressor and ejected through the cavities. However, this sealing flow also reduces the overall efficiency, and a compromise has to be found between the level of ingestion tolerated and the losses. Recent advances made in applying Computational Fluid Dynamics to such configurations are presented, with the aim of better understanding the physical phenomena and providing reliable design tools. First, results showing the pumping effect of the rotating disc are presented, including the influence of flow instabilities observed in both computational and experimental results. Second, the influence of the main annulus pressure asymmetries are analysed on a simplified representation of an available experiment, showing the combined influence of asymmetries generated by vanes and struts. Finally, a rim seal geometry representative of aero-engine design is studied in comparison to experiment, exhibiting the coupled influence of the cavity instabilities and annulus asymmetries.

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Дисертації з теми "Struts (Engineering) Dynamics"

Aharon, Ofer S. M. Massachusetts Institute of Technology. "Stress distributions around hydrofoils using computational fluid dynamics." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46382.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaf 108).
This research describes the reciprocal influence between two foils, vertically and horizontally oriented, on each other for different gaps between them. Those cases are the focus part of a bigger process of lowering significantly the drag of a ship when hydrofoils are attached to its hull. The research results are based on CFD analyses using the ADINA software. In order to verify the CFD process, a comparison was made between analytical, experimental and ADINA?s results for a single foil. The chosen foil was the famous Clark-Y foil; however a correction to its geometry was made using the Unigraphics software. Using the corrected geometry with an analytical solution well detailed and explained, the results of the CFD model were compared to experimental and analytical solutions. The matching of the results and the obtained accuracy are very high and satisfactory. In addition, the research contains an examination of the results when one of the boundary conditions is changed. Surprisingly, it was discovered that the FREE slip condition along the foil is much closer to reality than the NO slip condition. Another examination was stretching horizontally the foil and checking the pressure distribution behavior. Those results met exactly the expectations. As for the main core of this research, both the bi-plane case and the stagger case were found to be less effective than using a single foil. The conclusion of those investigations is that using those cases a few decades ago was for a structural reason rather than stability or speed. Since this research is very wide but also deep in its knowledge, references and academic work, many future research works may be based on it or go on from its detailed stages.
by Ofer Aharon.
S.M.

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Yi, Jun 1959. "Stress compatible bimaterial interface elements with application to transient dynamic stress analysis." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22842.

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Conventional displacement-based finite element programs do not yield unique values of stress components which ought to be continuous at element interfaces. The errors, being the differences from the correct unique values, become unacceptably large at a bimaterial interface when the moduli of the two materials are significantly different.
This thesis formulates and implements new finite elements for obtaining the correct values of the stress components, both continuous and discontinuous ones, at bimaterial interface points under general dynamic loading, assuming linear, isotropic, elastic material behaviour.
The constructed finite elements programs, suitable for analyzing two-dimensional and axisymmetric three-dimensional problems, have been validated by comparing the predicted responses with the exact analytical solutions of some non-trivial impact loading (wave-propagation) problems.
The work provides a necessary tool for analyzing and designing composite structures, for example prosthetic knee and hip joints in the biomechanics field.

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Maksym, Geoffrey N. "Computer controlled oscillator for dynamic testing of biological soft tissue strips." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69742.

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A computer controlled tissue strip oscillator has been constructed for the advanced study of lung parenchyma mechanics. The data acquisition and control are facilitated on a 486 personal computer. The tissue is maintained by a continuously circulating bath of Krebs-Ringer solution at 37$ sp circ$C bubbled with a 95% O$ sb2$ and 5% CO$ sb2$ gas mixture. The oscillator has a useful bandwidth to 20 Hz at 0.5 cm amplitude and step response with no overshoot at all amplitudes. The movement range of the motor is 5 cm with resolution 13.6 $ mu$m. The force resolution is 66 $ mu$N with a range of 0.25 N. A tissue preconditioning protocol was developed as a standard maneuver to be conducted prior to applying length perturbations about specific operating stresses. The tissue strip oscillator has been successfully tested on dog lung tissue strips.

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Rashedi, Ahmadreza. "The Design and Flow Dynamics of Non-Brownian Suspensions." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1598018383854045.

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Shim, Sang-Hea. "The effect of fluid flow on the stress corrosion cracking of sensitized type 304 stainless steel in 0.01 M Na₂SO₄ solution at 250⁰C /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487264603216315.

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Mikucka, Vita. "Dynamic problems for interface cracks under harmonic loading." Thesis, University of Aberdeen, 2015. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=228606.

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This thesis is devoted to solution of the two-dimensional elastodynamic problem for a cracked bimaterial loaded by harmonic waves. The system of boundary integral equations for displacements and tractions at the interface is obtained from Somigliana identity with the allowance for the contact interaction of the opposite crack faces. Full expressions of the integral kernels derived by the consecutive differentiation of the Green's displacement tensor are given. Due to the contact that takes place between the faces of the crack under the applied external loading, the resulting process is a steady-state periodic, but not a harmonic one. Thus, components of the stress-strain state are expanded into exponential Fourier series. The collocation method with a piecewise constant approximation on each linear continuous boundary element is used for the numerical solution. The problem is solved using the iterative algorithm. The solution is refined during the iteration process until the distribution of physical values satisfies the imposed constraints. The results are obtained for the interface crack subject to normal tension-compression, normal shear, or oblique tension-compression waves with different values of the angle of the wave incidence and the wide range of the dimensionless wave number. The distributions of the normal and tangential components of the contact forces and displacement discontinuities on the surface of the crack are investigated. The stress intensity factors are computed and analyzed for various values of the wave frequency, the friction coefficient, and material properties. The maximal stress intensity factors at the trailing crack tip differ from the SIF values at the leading crack tip showing non-symmetry of solution with respect the space and time variables. It is concluded that the crack closure and friction effect change the solution both qualitatively and quantitatively, as the difference between comparable results can achieve 30-50%.

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Marks, Christopher R. "Surface Stress Sensors for Closed Loop Low Reynolds Number Separation Control." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1309998636.

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Massahi, Aidin. "Multi-resolution Modeling of Dynamic Signal Control on Urban Streets." FIU Digital Commons, 2017. http://digitalcommons.fiu.edu/etd/3349.

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Dynamic signal control provides significant benefits in terms of travel time, travel time reliability, and other performance measures of transportation systems. The goal of this research is to develop and evaluate a methodology to support the planning for operations of dynamic signal control utilizing a multi-resolution analysis approach. The multi-resolution analysis modeling combines analysis, modeling, and simulation (AMS) tools to support the assessment of the impacts of dynamic traffic signal control. Dynamic signal control strategies are effective in relieving congestions during non-typical days, such as those with high demands, incidents with different attributes, and adverse weather conditions. This research recognizes the need to model the impacts of dynamic signal controls for different days representing, different demand and incident levels. Methods are identified to calibrate the utilized tools for the patterns during different days based on demands and incident conditions utilizing combinations of real-world data with different levels of details. A significant challenge addressed in this study is to ensure that the mesoscopic simulation-based dynamic traffic assignment (DTA) models produces turning movement volumes at signalized intersections with sufficient accuracy for the purpose of the analysis. Although, an important aspect when modeling incident responsive signal control is to determine the capacity impacts of incidents considering the interaction between the drop in capacity below demands at the midblock urban street segment location and the upstream and downstream signalized intersection operations. A new model is developed to estimate the drop in capacity at the incident location by considering the downstream signal control queue spillback effects. A second model is developed to estimate the reduction in the upstream intersection capacity due to the drop in capacity at the midblock incident location as estimated by the first model. These developed models are used as part of a mesoscopic simulation-based DTA modeling to set the capacity during incident conditions, when such modeling is used to estimate the diversion during incidents. To supplement the DTA-based analysis, regression models are developed to estimate the diversion rate due to urban street incidents based on real-world data. These regression models are combined with the DTA model to estimate the volume at the incident location and alternative routes. The volumes with different demands and incident levels, resulting from DTA modeling are imported to a microscopic simulation model for more detailed analysis of dynamic signal control. The microscopic model shows that the implementation of special signal plans during incidents and different demand levels can improve mobility measures.

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Farooque, Tanya Mahbuba. "Biochemical and mechanical stimuli for improved material properties and preservation of tissue-engineered cartilage." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26710.

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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Boyan, Barbara; Committee Chair: Wick, Timothy; Committee Member: Brockbank, Kelvin; Committee Member: Nenes, Athanasios; Committee Member: Sambanis, Athanassios. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Tadevosyan, Davit. "System dynamic framework for analyzing organizational stress : United States Postal Service case study." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/100365.

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Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, Engineering Systems Division, System Design and Management Program, 2014.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 102-106).
Stress, both individual and organizational, appears to be an increasing problem in any society, and more so in organizations. It already is taking a significant toll on corporate and national levels. Slow recovering economy and pressures on bottom lines, especially for financially constrained organizations, further emphasize the problem and call for new solutions. This paper explores two aspects of stress - individual and organizational. Our goal was to provide a systems dynamic framework that organizations, as well as individuals, can use to improve the understanding of the physiological and psychological stress loads, as well as understand their relationship to organizational key performance indicators. Like many natural systems, human body is the ultimate limited system. The main benefit of the proposed framework will be the ability to monitor cumulative variables of the functional capacity of human body to process stressors, and the mental and emotional capacity of employees to carry out their duties.
by Davit Tadevosyan.
S.M. in Engineering and Management

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Книги з теми "Struts (Engineering) Dynamics"

ill, Martin Cynthia 1961, and Milgrom A. ill, eds. The dynamic world of chemical reactions with Max Axiom, super scientist. Mankato, Minn: Capstone Press, 2011.

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Biskup, Agnieszka. The dynamic world of chemical reactions with Max Axiom, super scientist. Mankato, Minn: Capstone Press, 2011.

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Symposium, on Thermal Anemometry (1987 Cincinnati Ohio). Symposium on Thermal Anemometry: Presented at the 1987 ASME Applied Mechanics, Bioengineering, and Fluids Engineering Conference, Cincinnati, Ohio, June 14-17, 1987. New York, N.Y. (345 E. 47th St., New York 10017): American Society of Mechanical Engineers, 1987.

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Thiriet, Marc. Tissue Functioning and Remodeling in the Circulatory and Ventilatory Systems. New York, NY: Springer New York, 2013.

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Boudreau, Joseph F., and Eric S. Swanson. Continuum dynamics. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198708636.003.0019.

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The theory and application of a variety of methods to solve partial differential equations are introduced in this chapter. These methods rely on representing continuous quantities with discrete approximations. The resulting finite difference equations are solved using algorithms that stress different traits, such as stability or accuracy. The Crank-Nicolson method is described and extended to multidimensional partial differential equations via the technique of operator splitting. An application to the time-dependent Schrödinger equation, via scattering from a barrier, follows. Methods for solving boundary value problems are explored next. One of these is the ubiquitous fast Fourier transform which permits the accurate solution of problems with simple boundary conditions. Lastly, the finite element method that is central to modern engineering is developed. Methods for generating finite element meshes and estimating errors are also discussed.

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Zocchi, Giovanni. Molecular Machines. Princeton University Press, 2018. http://dx.doi.org/10.23943/princeton/9780691173863.001.0001.

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This book presents a dynamic new approach to the physics of enzymes and DNA from the perspective of materials science. Unified around the concept of molecular deformability—how proteins and DNA stretch, fold, and change shape—the book describes the complex molecules of life from the innovative perspective of materials properties and dynamics, in contrast to structural or purely chemical approaches. It covers a wealth of topics, including nonlinear deformability of enzymes and DNA; the chemo-dynamic cycle of enzymes; supra-molecular constructions with internal stress; nano-rheology and viscoelasticity; and chemical kinetics, Brownian motion, and barrier crossing. Essential reading for researchers in materials science, engineering, and nanotechnology, the book also describes the landmark experiments that have established the materials properties and energy landscape of large biological molecules. The book gives graduate students a working knowledge of model building in statistical mechanics, making it an essential resource for tomorrow's experimentalists in this cutting-edge field. In addition, mathematical methods are introduced in the bio-molecular context. The result is a generalized approach to mathematical problem solving that enables students to apply their findings more broadly.

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Dynamic World of Chemical Reactions With Max Axiom. Fitzhenry & Whiteside, 2010.

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United States. National Aeronautics and Space Administration., ed. An analysis code for the Rapid Engineering Estimation of Momentum and Energy Losses (REMEL). [Washington, DC]: National Aeronautics and Space Administration, 1994.

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Jones, Jack, and Larry K. Britt. Design and Appraisal of Hydraulic Fractures. Society of Petroleum EngineersRichardson, Texas, USA, 2009. http://dx.doi.org/10.2118/9781555631437.

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Using an interdisciplinary approach, Design and Appraisal of Hydraulic Fractures offers a basic yet comprehensive introduction to the completion and reservoir engineering aspects of hydraulic fracture stimulation. The book is divided into three sections. Section 1 covers the design and placement of a hydraulic fracture stimulation; topics include the basics of the hydraulic fracturing process, stress issues, fracture geometry, controls on generated length and width, fluid and proppant selection, quality control, and quality assurance. Section 2 introduces the use of dynamic data to characterize the in-place hydraulic fracture, outlining the methods of pressure-transient analysis for both pressure-drawdown and pressure-buildup tests. The discussion includes effective wellbore radius, effective fracture half-length, equivalent skin, and their relationships; simulated and field examples illustrate the basic analysis procedure and many common pitfalls. The final section covers the prediction of long-term rate performance and recoverable volumes. Three approaches are discussed: rate-decline type curves, analytical and semianalytical methods, and numerical simulation. Essential elements are given for each and illustrated with field examples. Design and Appraisal of Hydraulic Fractures is a valuable reference for all members of the geotechnical and surface engineering communities who need to understand the important issues around and the full impact of hydraulic fracture stimulation on well performance.

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(Editor), David E. Stock, American Society of Mechanical Engineers. Fluids Engineering Division (Corporate Author), Canadian Society for Mechanical Engineering Forum (Corporate Author), S. A. Sherif (Editor), and Alexander J. Smits (Editor), eds. Heuristics of Thermal Anemometry/Fed Vol 97/H00602: Presented at the 1990 Spring Meeting of the Fluids Engineering Division Held in Conjunction With the ... Society of Mechanical (Fed (Series), V. 97.). Amer Society of Mechanical, 1990.

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Частини книг з теми "Struts (Engineering) Dynamics"

Wang, Kun, Mengbo Liu, Shaoming Liao, and Jun Wu. "Mechanical Analysis of Supporting Struts for Special-Shaped Foundation Pits." In Proceedings of GeoShanghai 2018 International Conference: Advances in Soil Dynamics and Foundation Engineering, 561–69. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-13-0131-5_61.

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Thillaikumar, T., and Mrinal Kaushik. "Assessment of Struts in Gas-Dynamic Steering of a Supersonic Nozzle." In Lecture Notes in Mechanical Engineering, 675–82. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0698-4_74.

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Morozov, Nikita, and Yuri Petrov. "Stress Fields in Problems of Dynamic Fracture Mechanics." In Foundations of Engineering Mechanics, 52–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-540-69712-1_6.

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Kandaurov, I. I., and R. B. Zeidler. "Equations of dynamics; Probability and stress distribution." In Mechanics of Granular Media and its Application in Civil Engineering, 212–47. 2nd ed. London: Routledge, 2022. http://dx.doi.org/10.1201/9780203747827-4.

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Kumar, Mutyala Gowtham, and Gali Madhavi Latha. "Dynamic Properties of Soils—A Stress Path Approach." In Lecture Notes in Civil Engineering, 167–77. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-5669-9_14.

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Wen, Zitong, Jian Zhou, Jing Dong, and Chizhi Zhang. "Improvement Measures for Structure System Conversions Caused by Utilising SPMTs to Lift Trusses." In Lecture Notes in Civil Engineering, 11–17. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1260-3_2.

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AbstractSince the demand for accelerated construction is increasing these years, much attention has been paid to accelerated bridge construction (ABC) methods. The self-propelled modular transporters (SPMTs) are widely utilised in the ABC method as a versatile transport carrier. However, since the limitation of the SPMTs method, several structural system conversions will happen during truss installation, and tensile stress will potentially appear at the upper chord of the truss. Moreover, it is worth noticing the dynamic effects caused by utilising SPMTs to lift the truss can enlarge the impact of tensile stress. As one type of prestressing, beams prestressed with external tendons can effectively reduce the tensile stress. In order to reduce the impact of cracks caused by tensile stress, the feasibility of adopting temporary external pre-stressing tendons is discussed combined with the simulation results of MIDAS in this research.

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Kinne, Marko, Ronald Schneider, and Sebastian Thöns. "Reconstructing Stress Resultants in Wind Turbine Towers Based on Strain Measurements." In Lecture Notes in Mechanical Engineering, 224–35. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-77256-7_18.

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AbstractSupport structures of offshore wind turbines are subject to cyclic stresses generated by different time-variant random loadings such as wind, waves, and currents in combination with the excitation by the rotor. In the design phase, the cyclic demand on wind turbine support structure is calculated and forecasted with semi or fully probabilistic engineering models. In some cases, additional cyclic stresses may be induced by construction deviations, unbalanced rotor masses and structural dynamic phenomena such as, for example, the Sommerfeld effect. Both, the significant uncertainties in the design and a validation of absence of unforeseen adverse dynamic phenomena necessitate the employment of measurement systems on the support structures. The quality of the measurements of the cyclic demand on the support structures depends on (a) the precision of the measurement system consisting of sensors, amplifier and data normalization and (b) algorithms for analyzing and converting data to structural health information. This paper presents the probabilistic modelling and analysis of uncertainties in strain measurements performed for the purposes of reconstructing stress resultants in wind turbine towers. It is shown how the uncertainties in the strain measurements affect the uncertainty in the individual components of the reconstructed forces and moments. The analysis identifies the components of the vector of stress resultants that can be reconstructed with sufficient precision.

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Anjaneyulu, J., G. Krishna Mohana Rao, and G. Venkata Rao. "Stress Analysis of a Circuit Breaker Switchgear Mechanism by Using Multi Body Dynamics." In Lecture Notes in Mechanical Engineering, 183–93. New Delhi: Springer India, 2016. http://dx.doi.org/10.1007/978-81-322-2740-3_19.

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Shilko, Evgeny V., Alexey Yu Smolin, Andrey V. Dimaki, and Galina M. Eremina. "Particle-Based Approach for Simulation of Nonlinear Material Behavior in Contact Zones." In Springer Tracts in Mechanical Engineering, 67–89. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-60124-9_4.

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AbstractMethods of particles are now recognized as an effective tool for numerical modeling of dynamic mechanical and coupled processes in solids and liquids. This chapter is devoted to a brief review of recent advances in the development of the popular particle-based discrete element method (DEM). DEM is conventionally considered as a highly specialized technique for modeling the flow of granular media and the fracture of brittle materials at micro- and mesoscopic scales. However, in the last decade, great progress has been made in the development of the formalism of this method. It is largely associated with the works of the scientific group of Professor S. G. Psakhie. The most important achievement of this group is a generalized formulation of the method of homogeneously deformable discrete elements. In the chapter, we describe keystones of this implementation of DEM and a universal approach that allows one to apply various rheological models of materials (including coupled models of porous fluid-saturated solids) to a discrete element. The new formalism makes possible qualitative expansion of the scope of application of the particle-based discrete element technique to materials with various rheological properties and to the range of considered scales form microscopic to macroscopic. The capabilities of this method are especially in demand in the study of the features of contact interaction of materials. To demonstrate these capabilities, we briefly review two recent applications concerning (a) the effect of adhesive interaction on the regime of wear of surface asperities under tangential contact of bodies and (b) the nonmonotonic dependence of the stress concentration in the neck of the human femur on the dynamics of hip joint contact loading.

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Yang, Guoyue, Keyu Li, Yunlong Xu, and Liangji Li. "Dynamic Behaviors of Overconsolidated Remolded Red Clay Under Cyclic Compressive Stress Paths." In Lecture Notes in Civil Engineering, 297–309. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2349-6_18.

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Тези доповідей конференцій з теми "Struts (Engineering) Dynamics"

Kanyilmaz, Alper. "INELASTIC CYCLIC NUMERICAL ANALYSIS OF STEEL STRUTS USING DISTRIBUTED PLASTICITY APPROACH." In 5th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering Methods in Structural Dynamics and Earthquake Engineering. Athens: Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens (NTUA) Greece, 2015. http://dx.doi.org/10.7712/120115.3648.1949.

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Ainsworth, Stephen D., Jay M. Ochterbeck, Eugene M. Langan, and Martine LaBerge. "Computational Fluid Dynamics Analysis of Pulsatile Flow Over an Isolated Intravascular Stent Strut." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0242.

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Abstract Knowledge of the distinct fluid dynamic factors created by an intravascular stent, placed in an atherosclerotic artery and subjected to pulsatile flow, is limited. A computational fluid dynamics modeling approach was used in this research to analyze and measure the effect of single stent struts on the flow separation and reattachment points, and re-circulation regions. With the overall goal to effectively model a comprehensive stented atherosclerotic artery, this preliminary study focused on two dimensional flow at various points in the cross-section of a stent subjected to steady and pulsatile flow. The reattachment point is an area of increased wall shear stress gradients, and thus a concern when considering intimal hyperplasia. The results show that the reattachment point is a function of the longitudinal cross sectional geometry of the stent. Pulsatile flow results show the motion of the reattachment point with increasing and decreasing flow, as well as the relationship of the geometrical design of the stent and the existence of reattachment points between struts.

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Guan, Peng, and Hans DeSmidt. "Parametric Instability of Planetary Gear Transmission Mounted on Discrete Support Struts With Minimum Ring Gear Rim Thickness Design." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-87220.

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This research explores parametric instabilities of the PGT driveline system and a stability-based method for ring gear rim thickness design. Parametric excitation of a planetary gear transmission (PGT) driveline system arises from two sources: 1) gear mesh stiffness variation, 2) Interaction between moving planets, flexible ring gear and boundary struts. Many researchers have studied the parametric instability of planetary gear transmissions due to gear mesh stiffness variation, however, the effect of interaction between moving planets, flexible ring and discrete boundary struts on parametric instabilities has not been fully studied before. Especially, for sufficiently thin ring gears, this kind of effect becomes even more significant. To illustrate the novel PGT rim design proposal, firstly, a structural dynamics model of a complete PGT driveline system with elastic ring gear supported by discrete boundary struts is established. Secondly, by applying Floquet method, the parametric instability behavior due to the second parametric excitation source is fully investigated. Lastly, the design guidelines for planetary gear transmission ring gear rim thickness are proposed based on system stability from a dynamical viewpoint. The analysis and results provide new and important insights into dynamics and design of lightweight planetary gear transmission ring gear rim.

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Looyenga, Eric M., Aaron M. Propst, and Stephen P. Gent. "Investigating the Effects of Stent-Graft Structural Features Using Computational Fluid Dynamics." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71442.

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The objective of this study was to assess the effects structural features of endovascular stent-grafts used to repair abdominal aortic aneurysms (AAA) have on the flow mechanics and near-wall hemodynamics using Computational Fluid Dynamics (CFD) simulations. This research compared two test case model representations: 1) a stent graft that included the wire struts in the graft walls, and 2) a stent graft that excluded the struts in the computational mesh. The two computer-aided design models were created to represent a bifurcated stent graft in the abdominal aorta, with the stent beginning in the thoracic region of the aorta and branching into the common iliac arteries. The geometries were imported as surface meshes into a commercially available CFD solver. Both models account for viscous pulsatile blood flow of the cardiac cycle using blood properties gathered from previous research. Results of the two simulations were compared by using established metrics, including oscillating shear index (OSI), time average wall shear stress (TAWSS), and relative residence time (RRT), all of which are used to predict the likelihood of clot formation, endothelial damage, and device failure. Scalar and vector scenes allow for visualization, and data was exported for quantifying threshold results of the parameters. Due to the expense of stent grafts and the risks involved with clinical trial, CFD modeling is becoming more prominent in endovascular repair of aneurysms. The overarching goal of this study is to enhance current models of stent grafts, which can potentially be used to complement clinical trial for stent graft development.

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Markogiannaki, O., and I. Tegos. "PARAMETRIC INVESTIGATION FOR THE OPTIMIZATION OF A LONGITUDINAL SEISMIC RESTRAINING SYSTEM CONSISTING OF STRUTS-TIES FOR CONCRETE BRIDGES." In 4th International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering. Athens: Institute of Structural Analysis and Antiseismic Research School of Civil Engineering National Technical University of Athens (NTUA) Greece, 2014. http://dx.doi.org/10.7712/120113.4564.c1483.

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Vernengo, Giuliano, Yigit Kemal Demirel, Claire De Marco Muscat-Fenech, Stefano Gaggero, and Diego Villa. "Hydrodynamic Interactions of Multiple Surface-Piercing Struts by Smoothed Particles Hydrodynamics." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-81431.

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Abstract The hydrodynamics of surface piercing struts and pile-like structures in general presents some very complex fluid dynamics phenomena that are worth investigating. Among them there are the forward wave pile-up at stagnation, the wave breaking with flow reversal like that observed in Bidone-type hydraulic jumps, flow separation caused by interactions of steep free-surface waves and the turbulent wall boundary layer. Such a type of flow structures plays a key role in several engineering applications, ranging from naval architecture to civil and ocean engineering. The hydrodynamic analysis of different surface-piercing struts in tandem configuration has been done in the framework of a Smoothed Particle Hydrodynamic approach available through the open-source software DualSPHysics, developed to exploit the GP-GPU architecture to speed up the computation. A numerical wave tank has been set-up to carry out calm water tests. Beyond the influence of the forward speed, the analysis has focused on the effect of three main geometric parameters establishing the configuration: the longitudinal and the lateral distance among the vertical, surface-piercing, struts and the relative size among them. The mean and the rms values of the unsteady near-field free surface elevation have been analyzed and compared among the selected cases and interaction effects are studied in comparison to the free surface obtained for the equivalent single strut configuration.

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Christoffersen, Lasse M., Lennart Lo¨fdahl, and Anders Jo¨nson. "Wheel Strut Interference." In ASME 2006 2nd Joint U.S.-European Fluids Engineering Summer Meeting Collocated With the 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/fedsm2006-98511.

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To fine tune the aerodynamic properties of road going vehicles the flow along the underbody is of outmost importance. Hence moving ground facilities has been introduced. In full-width mono-belt facilities the test vehicle is most often suspended over the ground plane by a sting system. To mount the wheels, two possibilities exist. The designer of the wind tunnel model is faced with the choice to have the wheels on or off the model. The first option gives the most satisfying boundary conditions from a fluid dynamics point of view, however, the designer will face the problem of creating a frictionless chassis suspension system for the model. The “wheels off” type does not require such complex system but unfortunately creates a non-realistic flow due to the presence of so called wheel struts that carries the wheels. In the present work a numerical study of the flow around a “wheels off” model has been conducted. The study was performed to quantify how the presence of the wheel struts would affect the flow field and hence how this influence flow related measurements made on the model. The work has been done using a commercial CFD-code, running a standard k-epsilon model on a let-dominated mesh, counting roughly 6.5 million cells. As expected the flow field in the vicinity of the wheels is affected due to the extra vorticity introduced by the struts. The modified pressure field alters the drag and of further significance is the influence from the wheel struts on the underbody flow field. It is shown that care must be taken in studies of underbody and later underhood flows, using a “wheels-off” configuration.

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Main, John A., Suzanne Weaver Smith, Alexander L. Chapman, and Kenneth Patrick Hobbs. "Structural Dynamics and Damage Detection of Foam-Rigidized Deployable Aerospace Structures." In ASME 1997 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/detc97/vib-4232.

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Abstract The basic advantage of deployable structures, their compact stowed size relative to their final deployed size, presents a significant advantage to the aerospace designer. Extremely large structures that stow into very small volumes for launch are particularly feasible with one particular type of deployable, the inflated structure. However, it is difficult to advocate the use a purely inflated structure for an orbital mission because of the risk of micrometeor puncture. Rigidizing the structure in some fashion addresses this fragility issue. Design and operational issues with respect to foam-rigidized aerospace structures are investigated in this paper. The structures are fabricated from flexible Kapton film that is formed into a cylindrical shell. The shell is injected with a hardening urethane foam to form a composite strut. The results of both static and dynamic tests of four test coupons cut from foam rigidized struts are presented. The experimentally determined structural properties are then input into a finite–element model to gain insight into the dynamic behavior of a realistic inflated–rigidized structure. As with all structures touted for aerospace use, the survivability of foam–rigidized structures in the orbital environment is of interest. This issue is investigated by damaging the test coupons in a controlled fashion and then again experimentally evaluating the static and dynamic material properties. These properties are used for sections of the finite–element model to represent damage to the structure. An evaluation of the possibility of vibration–based damage assessment is included.

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Gori, F., A. Boghi, and M. Amitrano. "Three-Dimensional Numerical Simulation of the Fluid Dynamics in a Coronary Stent." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10301.

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Stents are commonly used to restore blood flow in patients with severe coronary artery disease. Local hemodynamic variables, as wall shear stress, have an important role in the restenosis and their distribution depends on the stent geometry. The objective of the present study is to carry out CFD simulations in a realistic 3D geometry of a coronary stent in physiological conditions. A comparison is performed between two reconstructed stents, made of 12 rings and similar to the real coronary ones, which differ by the position of the struts, where the first type is with closed cells and the second one with open cells. The artery is modeled as a cylinder with rigid walls and the blood is assumed as incompressible Newtonian fluid in laminar flow with constant physical properties. The commercial computational fluid dynamic code FLUENT is used with a mesh composed of non uniform tetrahedrons. The simulations are performed in steady and unsteady state. Wall shear stresses, WSS, as well as its time variations, are investigated in unsteady state with the conclusion that the stent with closed cells have a better fluid dynamic behavior.

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Centea, Dan N., Herve Lacheray, Frederic Audren, Richard Teltz, and Mohamed A. Elbestawi. "Development of the TIARA Hexapod: A Machine Tool Based on Parallel Kinematic Structures." In ASME 1999 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/imece1999-0752.

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Abstract The paper focuses on the TIARA Hexapod — a parallel kinematic machine tool that is being developed at McMaster University. The design uses fixed length struts, and an inclined layout for the motion axes that results in the mechanism resembling a ‘tiara’. In addition to the novelty of the design, these characteristics have several advantages from both a performance and economic perspective. The paper presents an overview of the development program for this machine tool, discussing issues related to design, modelling, inverse and forward kinematics, workspace, and dynamics analysis. Later sections of the paper detail the kinematic and dynamic models developed for the TIARA machine tool, and demonstrate their use for workspace analysis and the specification of actuator requirements.

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Звіти організацій з теми "Struts (Engineering) Dynamics"

Pichersky, Eran, Alexander Vainstein, and Natalia Dudareva. Scent biosynthesis in petunia flowers under normal and adverse environmental conditions. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699859.bard.

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The ability of flowering plants to prosper throughout evolution, and for many crop plants to set fruit, is strongly dependent on their ability to attract pollinators. To that end many plants synthesize a spectrum of volatile compounds in their flowers. Scent is a highly dynamic trait that is strongly influenced by the environment. However, with high temperature conditions becoming more common, the molecular interplay between this type of stress and scent biosynthesis need to be investigated. Using petunia as a model system, our project had three objectives: (1) Determine the expression patterns of genes encoding biosynthetic scent genes (BSGs) and of several genes previously identified as encoding transcription factors involved in scent regulation under normal and elevated temperature conditions. (2) Examine the function of petunia transcription factors and a heterologous transcription factor, PAPl, in regulating genes of the phenylpropanoid/benzenoid scent pathway. (3) Study the mechanism of transcriptional regulation by several petunia transcription factors and PAPl of scent genes under normal and elevated temperature conditions by examining the interactions between these transcription factors and the promoters of target genes. Our work accomplished the first two goals but was unable to complete the third goal because of lack of time and resources. Our general finding was that when plants grew at higher temperatures (28C day/22C night, vs. 22C/16C), their scent emission decreased in general, with the exception of a few volatiles such as vanillin. To understand why, we looked at gene transcription levels, and saw that generally there was a good correlation between levels of transcriptions of gene specifying enzymes for specific scent compounds and levels of emission of the corresponding scent compounds. Enzyme activity levels, however, showed little difference between plants growing at different temperature regimes. Plants expressing the heterologous gene PAPl showed general increase in scent emission in control temperature conditions but emission decreased at the higher temperature conditions, as seen for control plants. Finally, expression of several transcription factor genes decreased at high temperature, but expression of new transcription factor, EOB-V, increased, implicating it in the decrease of transcription of BSGs. The major conclusion of this work is that high temperature conditions negatively affect scent emission from plants, but that some genetic engineering approaches could ameliorate this problem.

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STUDY ON STATIC AND DYNAMIC EXPERIMENT OF SPATIAL CABLE-TRUSS STRUCTURE WITHOUT INNER RING CABLES BASED ON GRID-JUMPED LAYOUT OF STRUTS. The Hong Kong Institute of Steel Construction, December 2022. http://dx.doi.org/10.18057/ijasc.2022.18.4.6.

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Cable-truss tensile structures are one of the most imperative types of spatial structures, and a spatial cable-truss structure without inner ring cables (SCSWIRC) is a new type of cable-truss tensile structure. Although SCSWIRC has a strong anti-collapse capacity, its construction forming is difficult. Based on the concept of grid-jumped layout for struts, the experimental model with a span of 6 m is designed, and then three grid-jumped layout schemes are proposed to simplify structure system. The static and dynamic properties of experimental and finite element models are systematically studied. The results show that experimental values agree with simulation values. The errors of the static experiment are in the range of 6%~11.53% and the errors of the dynamic experiment are in the range of 5%~8%. The grid-jumped layout has negligible effects on the internal forces of cables. However, it has excellent effects on the internal forces of struts and nodal displacements at the grid-jumped layout, so the mechanical property of struts needs to be rechecked after grid-jumped layout. The mechanical property of the optimal grid-jumped layout scheme does not change compared with original scheme. The optimal grid-jumped layout scheme not only simplifies SCSWIRC, but also reduces the amount of steel. The study can promote the application of SCSWIRC in practical engineering.

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TENSILE BEHAVIOUR OF TMCP Q690D HIGH-STRENGTH STRUCTURAL STEEL AT STRAIN RATES FROM 0.00025 TO 760 S-1. The Hong Kong Institute of Steel Construction, March 2022. http://dx.doi.org/10.18057/ijasc.2022.18.1.7.

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The application of Q690D high-strength structural steel (HSSS) has been increasing in engineering structures. The lack of knowledge of the strain rate behaviour limits the application to the extreme loading conditions such as blast and impact loadings. This paper presents a series of tensile tests on the dynamic tensile behaviour of Q690D HSSS produced through the thermo-mechanical control process (TMCP). The stress-strain relationships of TMCP Q690D in the strain rate range of 0.00025 to 760 s-1 were measured by using the universal and servo-hydraulic high speed testing machines. The experimental results verified the sensitivity to strain rate of TMCP Q690D and the dynamic increase factor (DIF) for yield stress is identical to that of QT (Quenched and Tempered) S690 HSSS. However, TMCP Q690D behaves in a much different way in the strain hardening stage. The commonly-used Cowper-Symonds model was calibrated for the DIFs of yield stress and ultimate tensile strength. The Johnson-Cook (J-C) model was modified and a new rate-dependent constitutive model was proposed. The proposed model was validated successfully to predict the true stress-strain relationship, providing better prediction results than the modified J-C model.

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