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Relevant bibliographies by topics / Reducing curvature

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Academic literature on the topic 'Reducing curvature'

Author: Grafiati

Published: 4 June 2021

Last updated: 3 February 2022

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Journal articles on the topic "Reducing curvature"

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Bandyopadhyay, P. R. "Review—Mean Flow in Turbulent Boundary Layers Disturbed to Alter Skin Friction." Journal of Fluids Engineering 108, no. 2 (June 1, 1986): 127–40. http://dx.doi.org/10.1115/1.3242552.

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Recent developments in methods of reducing drag in turbulent boundary layers have been briefly reviewed. The behavior of the mean flow in several drag reducing boundary-layer flows of current interest, viz., those over longitudinal surface riblets, outer-layer devices (OLD’s), and longitudinal convex surface curvature, has been examined. The boundary layer on a surface with longitudinal concave curvature has been studied to complement the results of convex curvature. The riblets alter the flow in their vicinity only and cause no drag penalty. However, the OLD’s disturb the entire boundary layer, and it is the slow downstream (≃150 δ0) relaxation back to the equilibrium state that produces a region of lower skin friction; a net drag reduction results when the wall-drag reduction exceeds the drag penalty due to the device. The net drag reduction achieved by the riblets and OLD’s remains a modest 10 percent compared with the more spectacular levels reached by polymer addition and microbubble injection in water. Over mild convex curvatures, the outer-boundary-layer response is a function of the curvature ratio (δ0/R), and the relaxation rate after a length of convex curvature is a function of the curved length ratio (Δs0/δi). Boundary layers exhibit an asymmetric response to streamwise surface curvatures; the response is slower to a concave curvature than to a convex. Detailed turbulence and accurate wall shear stress measurements in the altered boundary layers are needed to understand the drag-reducing mechanisms involved.

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Etemadi, Ehsan, Abbas Naseri, and Mohsen Valinezhad. "Novel U-bending designed setups for investigating the spring-back/spring-go of two-layer aluminum/copper sheets through experimental tests and finite element simulations." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 234, no. 8 (June 5, 2020): 1142–53. http://dx.doi.org/10.1177/1464420720930251.

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This paper presents novel U-bending setups in order to investigate the effects of the curvatures created on the punch, die, or both on the spring-back/spring-go of the two-layer aluminum/copper sheets. Comparison of the new U-bending setups with the regular ones showed that the curvatures had important roles in reducing the spring-back/spring-go in the U-bending process. The results further indicated the good agreement between spring-back/spring-go and finite element simulations. Moreover, through finite element simulations, the effects of three effective parameters on reducing the spring-back/spring-go, including the curvature radius ( r) of the punch, the distance between curvature center and the fillet center ( d) in the punch, and the curvature radius at the end of the die ( R) were investigated. In achieving the desired state (90°), the results showed that the distance of curvature center from the fillet center ( d) was a more important parameter compared with the curvature radius at the end of the punch ( r) and the curvature radius at the end of the die ( R). This paper also focuses on the thicknesses of copper and aluminum as well as the stacking sequence of layers. Concerning the thicknesses of the implemented copper and aluminum change, the minimum angle of the spring-back/spring-go relative to the desired state was 75% Al/25% Cu thickness. Furthermore, the spring-back of aluminum/copper was lower than the copper/aluminum layer sheet. The effects of both thickness changing and stacking sequence of aluminum/copper layers on the spring-back/spring-go amounts of different sheets were due to the relocation of the neutral axis.

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Syahrullail, Samion, Md Razak Daud, Norzahir Sapawe, and Azli Yahya. "The Effect of Pits on the Curvature Cup: For Reducing Friction in Soft on Hard Sliding Contact." Applied Mechanics and Materials 819 (January 2016): 489–94. http://dx.doi.org/10.4028/www.scientific.net/amm.819.489.

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The purpose of this feasibility study is to elucidate the effect of surface modification on the curvature cup made of Acrylonitrile Butadiene Styrene (ABS) against metal ball bearing was investigated. In the tribology soft on hard (SoH), the pits embedded on the curvature cup have shown potential for reducing friction in curvature structure. A modified four ball machine as a hard-on-soft screening machine has been used to evaluate the friction on the curvature cup sample with an inner diameter of 12.8 mm. This study revealed that the treated curvature cup with pit in lubricated of palm oil optimizes the rate of frictional and allows for a stable of soft on hard sliding contact.

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Lovrić, Miroslav. "Curvature Pinching Based on Integral Norms of the Curvature." Canadian Journal of Mathematics 45, no. 3 (June 1, 1993): 599–611. http://dx.doi.org/10.4153/cjm-1993-031-1.

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AbstractA compact Riemannian manifold (M, g) of dimension 3 or higher admits a metric of constant (positive or negative) sectional curvature if the following conditions hold: the diameter is bounded from above, the part of the Ricci curvature which lies below some fixed negative number is bounded in LP norm for p > n/2, and the metric is almost spherical or almost hyperbolic in the LP sense. The idea of the proof is to obtain stronger (i.e. L∞) pinching by deforming the initial metric using the Ricci flow, thus reducing the problem to the theorems of Gromov in the case rg < 0 and of Grove, Karcher and Ruh in the case rg > 0. The reduced curvature tensor changes along the flow according to the heat equation, which implies a weak nonlinear parabolic inequality for its norm. The iteration method of De Giorgi, Nash and Moser is applied to obtain the estimate for the maximum norm of the reduced curvature tensor. The crucial step in the iteration consists of controlling the Sobolev constant of the appropriate imbedding (which also changes along the flow, but behaves well) by the isoperimetric constant, which, in turn, can be bounded in terms independent of the particular manifold.

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Yao, Jianjun, Fengshen Li, Junhua Chen, Zheng Yuan, and Wangeng Mai. "Parameter Analysis of Savonius Hydraulic Turbine Considering the Effect of Reducing Flow Velocity." Energies 13, no. 1 (December 19, 2019): 24. http://dx.doi.org/10.3390/en13010024.

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The Savonius-type hydraulic turbine, mainly known for its good self-starting properties and simple structure, not only has energy capturing characteristics but also has a certain effect on flow velocity reduction. Aside from ensuring energy capture efficiency, studying the effects of parameters on the flow velocity reduction capacity is of great significance for the protection of mariculture, as it can reduce the damage to cages and fishes. In this study, a computational fluid dynamics method was carried out to investigate the hydrodynamic characteristics and variations in the wake of a turbine. The accuracy of the simulation results was verified by experimental comparison. Firstly, the velocity contours and vectors were studied in detail to reveal the mechanism of the flow velocity reduction effect. Secondly, the velocity attenuation coefficient and relative attenuation length were formulated by the variation rule of the velocity field to evaluate the turbine reduction strength and range. Finally, the power coefficient was considered to predict the performance of a turbine under different tip speed ratios, overlap ratios, blade curvatures, and blade numbers. The results showed that the turbine had an obvious flow velocity reduction effect in the rear “sword”-shaped area, where the velocity field distribution had a certain regularity. In addition, by comprehensively comparing the simulation data, it was found that the respective effect trend of tip speed ratio, blade number, overlap ratio, and curvature on the turbine’s energy capture and flow velocity reduction characteristics was basically the same. Considering the effect of reducing flow velocity, a two-bladed turbine with a blade curvature of 0.8 and an overlap ratio of 0.15 is the optimal configuration.

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Naseath, G. B., and W. E. Red. "Reducing Curvature by Deviating CAM Tool Paths within a Tolerance Band." Computer-Aided Design and Applications 5, no. 6 (January 2008): 921–31. http://dx.doi.org/10.3722/cadaps.2008.921-931.

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Wu, Jin-mei, Xiao-dong Ling, Ya-wei Hou, Yu-xin Zhang, and Yi Wang. "Study on the Curvature Reducing Method of Non-linear Regression Model." MATEC Web of Conferences 63 (2016): 05033. http://dx.doi.org/10.1051/matecconf/20166305033.

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López, J., and J. Hernández. "On reducing interface curvature computation errors in the height function technique." Journal of Computational Physics 229, no. 13 (July 2010): 4855–68. http://dx.doi.org/10.1016/j.jcp.2010.03.032.

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Naesgaard, Ernest. "Lateral load tests to examine large-strain (seismic) behaviour of piles." Canadian Geotechnical Journal 29, no. 2 (April 1, 1992): 245–52. http://dx.doi.org/10.1139/t92-028.

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Three different 406 mm diameter piles were tested with lateral, vertical, and moment loadings. The purpose of the full-scale field tests was to assess the ability of the piles to withstand large lateral deformations that may be caused by earthquake-induced soil liquefaction. Two concrete shaft piles were tested to failure with lateral displacements at the pile top of up to 300 and 650 mm and pile curvatures of up to 0.16 and 0.35 rad/m, respectively. The third pile, a concrete-filled steel pipe shaft pile, reached a maximum lateral displacement at the pile top of 550 mm and a curvature of 0.08 rad/m without failure or significant distress. It is concluded that stronger piles that push through the soil may tolerate larger lateral displacements than weaker piles and that reducing the spiral reinforcing pitch from 150to 100 mm on concrete piles greatly increases the pile ductility. Key words : lateral load test, piles, reinforced concrete, concrete-filled pipe, seismic, liquefaction, pile curvature.

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Varna, Janis, Magnus Persson, and Abdelghani Hajlane. "Microdamage, Viscoelasticity and Viscoplasticity as Main Phenomena in Thermal Stress Relaxation in Laminated Composites." Key Engineering Materials 713 (September 2016): 99–102. http://dx.doi.org/10.4028/www.scientific.net/kem.713.99.

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Microdamage, viscoplastic and viscoelastic strain development in 90-layers of cross-ply laminates subjected to tensile loading is studied on unsymmetrical GF/EP laminates measuring the thermal curvature change. All three phenomena partially compensate for the effect of the thermal mismatch reducing the residual stress (specimen curvature). The viscoplastic strain contribution to curvature change is the largest whereas the effect of transient viscoelasticity is the smallest. Damage is included in the analysis through its effect on the effective transverse modulus of the 90-layer.

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Dissertations / Theses on the topic "Reducing curvature"

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Naseath, George Benjamin. "Reducing Curvature in Complex Tool Paths by Deviating from CAM-Produced Tool Paths Within a Tolerance Band." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2245.pdf.

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Book chapters on the topic "Reducing curvature"

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Akinci, Halil, Mustafa Zeybek, and Sedat Dogan. "Evaluation of Landslide Susceptibility of Şavşat District of Artvin Province (Turkey) Using Machine Learning Techniques." In Landslides [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99864.

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The aim of this study is to produce landslide susceptibility maps of Şavşat district of Artvin Province using machine learning (ML) models and to compare the predictive performances of the models used. Tree-based ensemble learning models, including random forest (RF), gradient boosting machines (GBM), and extreme gradient boosting (XGBoost), were used in the study. A landslide inventory map consisting of 85 landslide polygons was used in the study. The inventory map comprises 32,777 landslide pixels at 30 m resolution. Randomly selected 70% of the landslide pixels were used for training the models and the remaining 30% were used for the validation of the models. In susceptibility analysis, altitude, aspect, curvature, distance to drainage network, distance to faults, distance to roads, land cover, lithology, slope, slope length, and topographic wetness index parameters were used. The validation of the models was conducted using success and prediction rate curves. The validation results showed that the success rates for the GBM, RF, and XGBoost models were 91.6%, 98.4%, and 98.6%, respectively, whereas the prediction rate were 91.4%, 97.9%, and 98.1%, respectively. Therefore, it was concluded that landslide susceptibility map produced with XGBoost model can help decision makers in reducing landslide-associated damages in the study area.

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Keiko Lima Fujita, Alessandra, Daniel José Chianfrome, Vinicius Sigari Moreira, Anderson Luiz Zanchin, Priscila Fernanda Campos de Menezes, and Vanderlei Salvador Bagnato. "Anatomically Adjustable Device for Large-Area Photodynamic Therapy." In Photodynamic Therapy - from Basic Science to Clinical Research [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93917.

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The illumination system composed of LEDs is an anatomically adjustable device of high intensity that can be applied in different areas of the body. It can be applied in health care, as in the dermatological and esthetic treatments. The device improved the treatment of pathological diseases (e.g. actinic keratosis) since disseminated lesions were reached in a single application, thus reducing the time of the procedure and ensuring homogeneous light distribution. It was compared with a smaller and non-adjustable illumination device and evaluated in the treatment of actinic keratosis. The results showed its versatile application and a uniform adjustment to body curvatures.

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Conference papers on the topic "Reducing curvature"

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E. Daber, R., and T. H. Boe. "Using Azimuthal Curvature as a Method for Reducing Noise in Post Stack Curvature Volumes." In 72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010. European Association of Geoscientists & Engineers, 2010. http://dx.doi.org/10.3997/2214-4609.201400727.

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Rogelj, Luka, Urban Pavlovčič, Matija Jezeršek, Matija Milanic, and Urban Simončič. "Reducing object curvature and height variation effects in hyperspectral images." In Diffuse Optical Spectroscopy and Imaging, edited by Hamid Dehghani and Heidrun Wabnitz. SPIE, 2019. http://dx.doi.org/10.1117/12.2526990.

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Yenugu, Malleswar, Amit K. Ray, Samir Biswal, and Arindam Dutta. "Applications of Curvature Attributes in reducing the Drilling Risk — A Case History." In SEG Technical Program Expanded Abstracts 2010. Society of Exploration Geophysicists, 2010. http://dx.doi.org/10.1190/1.3513148.

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Cerantola, D. J., M. S. Zawislak, and A. M. Birk. "Reducing Nacelle Pressure Drag." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63978.

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Decreasing drag on aircraft components was beneficial towards improving fuel economy and operational range. A generic axisymmetric nacelle-strut configuration typical of those housing fuselage-mounted engines was evaluated at a Reynolds number of 6 × 105 based on the nacelle maximum diameter d = 26.5 cm and an angle of attack of 20 deg. It was estimated that drag could be reduced by 20%. Three case studies were evaluated that added a fillet to the nacelle-strut corner, vortex generating triangular tabs, and flow-path obstructing vanes to improve flow control by reducing suction-side separation. Experimental results showed that a 0.11 d radius of curvature fillet reduced drag by 8% with respect to the baseline case. Numerical results employing the realizable k-ε turbulence model with wall functions predicted no improvements with the tabs and an 8% reduction with the vanes.

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Harvey, C. M., F. Yu, J. C. Knight, W. J. Wadsworth, and P. Almeida. "Reducing Nonlinear Limitations of Ytterbium Mode-Locked Fibre Lasers with Hollow-Core Negative Curvature Fibre." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_si.2015.sth1l.5.

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Haigh, Casey D., John H. Crews, Shiquan Wang, and Gregory D. Buckner. "Modeling and Experimental Validation of Shape Memory Alloy Bending Actuators." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-7974.

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In this paper, we develop a computational model that can be used to investigate and optimize the performance of shape memory alloy (SMA) bending actuators. These actuators (approximately 7–21 mm in length) consist of curved SMA wires embedded within elastic sleeves and are intended for positioning and anchoring robotic catheters inside blood vessels during clinical treatments. Each SMA wire is shape-set to an initial curvature and inserted along the neutral axis of a straight elastic member (cast heat-resistant silicone with varying section modulus). The elastic member preloads the SMA (or produces a stress-induced phase transformation), reducing the equilibrium curvature of the composite actuator. Temperature-induced phase transformations in the SMA (via Joule heating) enable strain recovery and increased bending (increased curvature) in the composite actuator. The homogenized energy framework is utilized to model the behavior of this composite actuator, and the effects of several critical design parameters (initial SMA curvature and section modulus of the elastic member) on the deactivated and activated curvatures are investigated. Experimental results validate the model, enabling its use as a design tool for bending performance optimization.

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Hartland, Jonathan, and David Gregory-Smith. "A Design Method for the Profiling of End Walls in Turbines." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30433.

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The profiling of end walls in turbines has proved to be effective in reducing secondary flows and losses in turbines, both in cascades and in a turbine representative rig. This paper presents a simple method for the design of end walls using the philosophy that the blade (or rather flow) curvature causes the cross passage pressure gradient, so that mirroring the blade curvature on the end-wall should assist in canceling this effect. Three alternative end-wall profiles have been designed based on the camber line of the blades. From a CFD investigation into the effects of these profiles, they should all be effective in reducing the secondary flow within the cascade. The best profile extended upstream and downstream of the blades to attempt to overcome the problems associated with sharp curvature at inlet and exit from the blade row. For the best profile the CFD predicts a 6% reduction in secondary loss and a 61% reduction in secondary kinetic energy. Whilst the loss predictions are not expected to be accurate, the reduction in secondary kinetic energy is likely to be similar to that achieved if the profile were tested experimentally. Experience with testing of an earlier end wall (Hartland et al [1]) suggests that there is likely to be a substantial reduction in secondary loss accompanying this level of reduction in secondary kinetic energy.

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Fatemi, Ali, Shawn Kenny, Millan Sen, Joe Zhou, Farid Taheri, and Mike Paulin. "Parameters Affecting the Buckling and Post-Buckling Behaviour of High Strength Pipelines." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79578.

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Using the finite element methods, a parametric study was conducted to examine the influence of pipeline diameter, internal pressure, girth weld offset misalignment amplitude and modeled length on the local buckling of high strength pipelines. The numerical procedures were calibrated from full-scale tests on high strength pipelines subject to internal pressure and end rotation. The peak moment decreased with increasing pressure and girth weld offset misalignment amplitude. The limit curvature increased with increasing pressure and decreased with increasing girth weld offset misalignment amplitude. The effect of reducing the modeled pipeline segment length, from 5.5 D to 3.5 D, was to increase the limit curvature at the peak moment and to delay the onset of nonlinear ovalization response to higher curvature amplitudes. The influence of girth weld offset misalignment on the local buckling response was examined in terms of a strain capacity reduction parameter known as the girth weld factor. This study has determined current practice, based on DNV OS-F101 standard, was appropriate; moreover, the potential for reduction in this conservative approach is identified.

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Vankerschaver, Joris, Eva Kanso, and Jerrold E. Marsden. "The Motion of Solid Bodies in Potential Flow With Circulation: A Geometric Outlook." In ASME 2008 Dynamic Systems and Control Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/dscc2008-2292.

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The motion of a circular body in 2D potential flow is studied using symplectic reduction. The equations of motion are obtained starting from a kinetic-energy type system on a space of embeddings and reducing by the particle relabelling symmetry group and the special Euclidian group. In the process, we give a geometric interpretation for the Kutta-Joukowski lift force in terms of the curvature of a connection on the original phase space.

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Duraipandi, Devasena, John M. Heck, Raymond K. Yee, and Sang-Joon J. Lee. "A Finite Element Study of Geometric Modifications to Reduce Thermal Mismatch Curvature in Wafer Bonding." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41453.

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Wafer-level packaging of RF MEMS devices offers an attractive option to reduce packaging cost significantly and ensures hermetic encapsulation of devices. Low-temperature cofired ceramic (LTCC) cap wafers are particularly favorable because they can be pre-patterned with through-wafer vias for integrated electrical contacts and high-density packaging, at a much lower cost than silicon wafers with similar features. However, thermal expansion mismatch between ceramic and silicon wafers at high bonding temperatures induces thermal stresses at the interface, resulting in wafer curvature. For example, a 150 mm silicon wafer 675 μm thick with a ceramic cap wafer 500 μm thick has been measured to exhibit out-of-flatness displacement as severe as of 1.7 mm at the center. While the curvature can be reduced significantly using low-thermal-expansion ceramic, such materials are non-standard and require custom formulation. Furthermore, as the wafer diameter is increased, thermal expansion mismatch becomes more problematic. Therefore, it is desirable to address the problem using a geometrical approach in addition to optimizing the ceramic for wafer bonding applications. The present study applies finite element analysis (FEA) to examine the potential for reducing such curvature by introducing slots in the ceramic cap wafer. Two-level factorial design simulations involving five parameters were conducted to investigate the effect of slot parameters on wafer curvature, using 2-D plane strain simulation of wafer cooling from 300 °C to 25 °C. The five parameters investigated were cap wafer thickness, slot width, slot depth, slot separation, and slot orientation. The nonlinear temperature dependence of thermal expansion was also examined based on test data for the ceramic wafers. Furthermore, a 3-D finite element simulation was conducted to compare the 2-D results to overall impact on wafer distortion. FEA results were compared with experimental curvature measurements on sample wafers measured by coordinate measuring machining (CMM). Simulated results suggest that introduction of slots shows reduction in wafer curvature, and the displacement can be reduced by as much as 25% based on the geometric parameter values for slots in the cap wafer.

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Reports on the topic "Reducing curvature"

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Rush, Jason, Yevhen Holubnyak, and Willard Watney. Prototyping and Testing a New Volumetric Curvature Tool for Modeling Reservoir Compartments and Leakage Pathways in the Arbuckle Saline Aquifer: Reducing Uncertainty in CO₂ Storage and Permanence. Office of Scientific and Technical Information (OSTI), December 2016. http://dx.doi.org/10.2172/1353040.

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