Journal articles on the topic 'Higher geometric twists'
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1
Pym, Brent, and Pavel Safronov. "Shifted Symplectic Lie Algebroids." International Mathematics Research Notices 2020, no. 21 (September 7, 2018): 7489–557. http://dx.doi.org/10.1093/imrn/rny215.
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Abstract Shifted symplectic Lie and $L_{\infty }$ algebroids model formal neighborhoods of manifolds in shifted symplectic stacks and serve as target spaces for twisted variants of the classical topological field theory defined by Alexandrov--Kontsevich--Schwarz--Zaboronsky. In this paper, we classify zero-, one-, and two-shifted symplectic algebroids and their higher gauge symmetries, in terms of classical geometric “higher structures”, such as Courant algebroids twisted by $\Omega ^{2}$-gerbes. As applications, we produce new examples of twisted Courant algebroids from codimension-two cycles, and we give symplectic interpretations for several well-known features of higher structures (such as twists, Pontryagin classes, and tensor products). The proofs are valid in the $C^{\infty }$, holomorphic, and algebraic settings and are based on a number of technical results on the homotopy theory of $L_{\infty }$ algebroids and their differential forms, which may be of independent interest.
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Zhu, Wei. "A geometric higher twist effect on nuclear target." Nuclear Physics A 753, no. 1-2 (May 2005): 206–32. http://dx.doi.org/10.1016/j.nuclphysa.2005.02.085.
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Evans, David E., and Ulrich Pennig. "Equivariant higher twisted K$K$‐theory of SU(n)$SU(n)$ for exponential functor twists." Journal of Topology 15, no. 2 (June 2022): 896–949. http://dx.doi.org/10.1112/topo.12219.
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Phila, Arnut, Chinaruk Thianpong, and Smith Eiamsa-ard. "Influence of Geometric Parameters of Alternate Axis Twisted Baffles on the Local Heat Transfer Distribution and Pressure Drop in a Rectangular Channel Using a Transient Liquid Crystal Technique." Energies 12, no. 12 (June 18, 2019): 2341. http://dx.doi.org/10.3390/en12122341.
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This paper reports the effects of alternate axis twisted baffle geometric parameters on the heat transfer and flow characteristics within rectangular channels. In our experiments we used modified shapes of alternate axis twisted baffles according to relative pitch ratios (s/w) equal to 2–12 and twist ratios (y/w) equal to 1–5, under conditions where the angle of attack (α) was 90° and the relative blockage height (e/Dh) was at a constant value of 0.095. The results for the Reynolds numbers based on the duct hydraulic diameter ranged from 9000 to 24,000 at a constant Prandtl number, Pr = 0.707, using air as a working fluid. A 0.05 mm thick stainless-steel foil was used as a heater, and a thermochromic liquid crystal technique was used to obtain the local temperature distribution on the heated surfaces. Images were captured in areas with periodic, fully developed regions in the channel. The results show that rectangular channels equipped with alternate axis twisted baffles demonstrated 80%–185% greater heat transfer than rectangular channels with no baffles. Channels with alternate axis twisted baffles at higher twist ratios (y/w) and smaller relative pitch ratios (s/w) showed increased heat transfer, as well as pressure loss within the system, compared with other types of twisted baffles. The thermal enhancement factor of the rectangular channels equipped with alternate axis twisted baffles was higher than that for transverse baffles and smooth channels under similar operating conditions.
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Ohrt, Chris. "Twisted higher smooth torsion." Topology and its Applications 272 (March 2020): 107060. http://dx.doi.org/10.1016/j.topol.2020.107060.
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Ikeda, Noriaki. "Higher Dimensional Lie Algebroid Sigma Model with WZ Term." Universe 7, no. 10 (October 19, 2021): 391. http://dx.doi.org/10.3390/universe7100391.
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We generalize the (n+1)-dimensional twisted R-Poisson topological sigma model with flux on a target Poisson manifold to a Lie algebroid. Analyzing the consistency of constraints in the Hamiltonian formalism and the gauge symmetry in the Lagrangian formalism, geometric conditions of the target space to make the topological sigma model consistent are identified. The geometric condition is an universal compatibility condition of a Lie algebroid with a multisymplectic structure. This condition is a generalization of the momentum map theory of a Lie group and is regarded as a generalization of the momentum section condition of the Lie algebroid.
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Wang, Jun, Yaohui Liu, and Ruoxi Ding. "Analysis of Heat Transfer and Flow Characteristics of a Helically Coiled Tube with Twisted Elliptical in a Low Reynolds Number Flow." Processes 10, no. 11 (October 30, 2022): 2229. http://dx.doi.org/10.3390/pr10112229.
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In this paper, the heat transfer and flow characteristics of a helically coiled tube with twisted elliptical in a low Reynolds number (Re = 500–3000) flow were investigated numerically. The working fluid flowed in a laminar regime. Numerical results were compared with empirical correlations in the existing literature, demonstrating the accuracy of the analysis in this study. Firstly, we investigated the effects of geometric parameters and Reynolds number on the heat transfer and flow characteristics. The results showed that lower twist pitch length and semi-major axis length could induce sufficient fluid mixing and a larger temperature gradient near the tube wall, enhancing the heat exchange and producing larger friction resistance. Overall, the heat transfer performances were improved by about 1.04–1.21 times and 1.02–1.23 times for different semi-major axis lengths and different twist pitch lengths, respectively, compared to the smooth helical coil. Secondly, by changing the working fluid, it was found that the Nu when oil was chosen as the working fluid was all 6–6.8 times higher than that of water. Moreover, the effect of using Al2O3 nanofluids with a concentration of 0.10 wt.%, 0.25 wt.% and 0.50 wt.% was discussed. It can be seen that the heat transfer capacity of nanofluids increased by approximately 2–18% compared to the reference model with water as the working fluid, and the nanofluid solution with higher concentration has better heat transfer performance. Finally, Nu and f correlations are given to predict the heat transfer and pressure drop in practical applications.
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Noohi, Behrang, and Matthew B. Young. "Twisted loop transgression and higher Jandl gerbes over finite groupoids." Algebraic & Geometric Topology 22, no. 4 (October 10, 2022): 1663–712. http://dx.doi.org/10.2140/agt.2022.22.1663.
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Smith, Ivan. "Floer Theory of Higher Rank Quiver 3-folds." Communications in Mathematical Physics 388, no. 3 (November 11, 2021): 1181–203. http://dx.doi.org/10.1007/s00220-021-04252-2.
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AbstractWe study threefolds Y fibred by $$A_m$$ A m -surfaces over a curve S of positive genus. An ideal triangulation of S defines, for each rank m, a quiver $$Q(\Delta _m)$$ Q ( Δ m ) , hence a $$CY_3$$ C Y 3 -category $$\mathcal {C}(W)$$ C ( W ) for any potential W on $$Q(\Delta _m)$$ Q ( Δ m ) . We show that for $$\omega $$ ω in an open subset of the Kähler cone, a subcategory of a sign-twisted Fukaya category of $$(Y,\omega )$$ ( Y , ω ) is quasi-isomorphic to $$(\mathcal {C},W_{[\omega ]})$$ ( C , W [ ω ] ) for a certain generic potential $$W_{[\omega ]}$$ W [ ω ] . This partially establishes a conjecture of Goncharov (in: Algebra, geometry, and physics in the 21st century, Birkhäuser/Springer, Cham, 2017) concerning ‘categorifications’ of cluster varieties of framed $${\mathbb {P}}GL_{m+1}$$ P G L m + 1 -local systems on S, and gives a symplectic geometric viewpoint on results of Gaiotto et al. (Ann Henri Poincaré 15(1):61–141, 2014) on ‘theories of class $${\mathcal {S}}$$ S ’.
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Bochicchio, Marco. "Higher-Spin Currents, Operator Mixing and UV Asymptotics in Large-N QCD-like Theories." Universe 9, no. 2 (January 17, 2023): 57. http://dx.doi.org/10.3390/universe9020057.
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We extend to operator mixing—specifically, to higher-spin twist-2 operators—the asymptotic theorem on the ultraviolet asymptotics of the spectral representation of 2-point correlators of multiplicatively renormalizable operators in large-N confining QCD-like theories. The extension is based on a recent differential geometric approach to operator mixing that involves the Poincaré-Dulac theorem and allows us to reduce generically the operator mixing to the multiplicatively renormalizable case, provided that γ0β0 is diagonalizable and a certain nonresonant condition for its eigenvalues holds according to the Poincaré-Dulac theorem, with γ0 and β0 the one-loop coefficients of the anomalous dimension matrix and beta function respectively. Relatedly, we solve a conundrum about the generic nonconservation of higher-spin currents versus the conservation—up to contact terms—of the corresponding free propagators in the spectral representation of 2-point correlators of higher-spin operators of pure integer spin to the leading large-N order.
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Li, Zhi Min. "New Results of Buckling and Postbuckling Behaviors for Fiber-Reinforced Composite Shear Deformable Anisotropic Laminated Cylindrical Shell Subjected to Torsion." Applied Mechanics and Materials 117-119 (October 2011): 89–91. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.89.
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New results of buckling and postbuckling analysis are presented for a shear deformable anisotropic laminated cylindrical shell of finite length subjected to torsion. The governing equations are based on a higher order shear deformation shell theory with von Kármán-Donnell-type of kinematic nonlinearity and including the extension/twist, extension/flexural and flexural/twist couplings. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, moderately thick, anisotropic laminated cylindrical shells with different values of shell parameters and stacking sequence. The postbuckling equilibrium path is unstable for a moderately thick laminated cylindrical shell under torsion and the shell structure is virtually imperfection-sensitive.
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Syzrantsev, Vladimir, and Ksenia Syzrantseva. "Study of geometric characteristics of the arc teeth semi-rolled cylindrical gear meshing." FME Transactions 49, no. 2 (2021): 367–73. http://dx.doi.org/10.5937/fme2102367s.
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In the conditions of unbraced machine body parts, arc teeth cylindrical gears have a higher load capacity, durability and reliability as well as the ability to compensate for the twist angle by self-adjustment of one of the wheels compared to straight and helical teeth gears. Use of such gears in a semi-rolled version allows simplifying significantly the technological process of cutting wheels and making gears with large gear ratios. In this article, mathematical models of wheel and gear arc teeth forming process are built for a semi-rolled cylindrical gear. The geometric characteristics of the gear arc teeth meshing in the presence of errors in the wheel and gear relative position, required to solve the problem of calculating the gear load capacity and durability, have been determined.
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Dall'Agata, Gianguido, Nikolaos Prezas, Henning Samtleben, and Mario Trigiante. "Gauged supergravities from twisted doubled tori and non-geometric string backgrounds." Nuclear Physics B 799, no. 1-2 (August 2008): 80–109. http://dx.doi.org/10.1016/j.nuclphysb.2008.02.020.
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de Boer, J., M. B. Halpern, and C. Helfgott. "Twisted Einstein Tensors and Orbifold Geometry." International Journal of Modern Physics A 18, no. 20 (August 10, 2003): 3489–553. http://dx.doi.org/10.1142/s0217751x03015271.
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Following recent advances in the local theory of current-algebraic orbifolds, we study various geometric properties of the general WZW orbifold, the general coset orbifold and a large class of (nonlinear) sigma model orbifolds. Phase-space geometry is emphasized for the WZW orbifolds — while for the sigma model orbifolds we construct the corresponding sigma model orbifold action, which includes the previously-known general WZW orbifold action and general coset orbifold action as special cases. We focus throughout on the twisted Einstein tensors with diagonal monodromy, including the twisted Einstein metric, the twisted B field and the twisted torsion field of each orbifold sector. Finally, we present strong evidence for a conjectured set of twisted Einstein equations which should describe those sigma model orbifolds in this class which are also one-loop conformal.
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Rokvam, Sondre Østli, Nils Petter Vedvik, Lukas Mark, Eivind Rømcke, Jon Schawlann Ølnes, Luca Savio, and Andreas Echermeyer. "Experimental Verification of the Elastic Response in a Numeric Model of a Composite Propeller Blade with Bend Twist Deformation." Polymers 13, no. 21 (October 30, 2021): 3766. http://dx.doi.org/10.3390/polym13213766.
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Adaptive composite propeller blades showing bend twist behaviour have received increasing interest from hydrodynamic and structural engineers. When exposed to periodic loading conditions, such propellers can be designed to have higher energy efficiency and emit less noise and vibration than conventional propellers. This work describes a method to produce an adaptive composite propeller blade and how a point load experiment can verify the predicted elastic response in the blade. A 600 mm-long hollow full-size blade was built and statically tested in the laboratory. Finite element modelling predicted a pitch angle change under operational load variable loads of 0.55°, a geometric change that notably compensates for the load cases. In the laboratory experiment, the blade was loaded at two points with increasing magnitude. The elastic response was measured with digital image correlation and strain gauges. Model predictions and experimental measurements showed the same deformation patterns, and the twist angle agreed within 0.01 degrees, demonstrating that such propellers can be successfully built and modelled by finite element analysis.
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LI, ZHI-MIN, and HUI-SHEN SHEN. "POSTBUCKLING OF SHEAR-DEFORMABLE ANISOTROPIC LAMINATED CYLINDRICAL SHELLS UNDER AXIAL COMPRESSION." International Journal of Structural Stability and Dynamics 08, no. 03 (September 2008): 389–414. http://dx.doi.org/10.1142/s0219455408002715.
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A postbuckling analysis is presented for a shear-deformable anisotropic laminated cylindrical shell of finite length subjected to axial compression. The material of each layer of the shell is assumed to be linearly elastic, anisotropic and fiber-reinforced. The governing equations are based on a higher order shear-deformable shell theory with the von Kármán–Donnell type of kinematic nonlinearity and including the extension/twist, extension/flexural and flexural/twist couplings. The nonlinear prebuckling deformations and initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the buckling loads and postbuckling equilibrium paths. The numerical illustrations concern the postbuckling response of perfect and imperfect, moderately thick, anisotropic laminated cylindrical shells with different values of shell parameters and stacking sequence. The results confirm that there exists a compressive stress along with an associate shear stress and twisting when the anisotropic shell is subjected to axial compression. The postbuckling equilibrium path is unstable for the moderately thick cylindrical shell under axial compression and the shell structure is imperfection-sensitive.
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Majeti, Rohin Kumar, and Stephan Benz. "Mission-based optimal morphing parameters for rotors with combined chord and twist morphing." Open Research Europe 1 (June 7, 2022): 121. http://dx.doi.org/10.12688/openreseurope.14060.2.
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Background: The rotor blades with fixed geometry in today’s helicopters do not give the best performance throughout the duration of any mission. However, low-speed and high-speed flights have different geometrical requirements for the shape of the most efficient rotor blades. With advancements in morphing technologies, these can be applied to change the shape of the blades between different flight regimes. Methods: Two different helicopter rotor morphing concepts – namely, the linearly variable chord extension and the torque-tube based twist - under the framework of the European project SABRE were investigated for their optimal geometric parameters using a Particle Swarm Optimization (PSO) algorithm. Since the morphing parameters were dependent on the mission profile, three different missions representing typical helicopter applications were chosen. The optimization problem was posed both as single objective (power) and as multi-objective (power, tip elastic torsion and vibratory hub load). Based on the insights drawn from these investigations, a rotor was set up including both morphing concepts in a single blade. Results: The rotor with combined chord and twist morphing was shown to give performance improvement of 6.8% over the baseline blade for a whole mission while keeping the penalty on the elastic torsion and vibration of the rotor to a minimum. The performance improvement was higher at 13% for hover and low speed flight of µ = 0.14. Conclusions: Chord and twist are both important parameters determining the efficiency of a rotor blade. Since they have non-overlapping requirements, combining the two morphing concepts into a single blade can yield higher performance than the individual ones.
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Ramesh, B., A. Elayaperumal, and S. Satishkumar. "Drillability study of pultruded and sheet moulding compound thick polymeric composites." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 231, no. 2 (August 8, 2016): 268–85. http://dx.doi.org/10.1177/0954405415573678.
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This article discusses the effects of process parameters (feed and spindle speed) on quality characteristics (thrust force, torque, surface roughness and ovality) for standard and special geometric design of a drill body in dry drilling of pultruded and sheet moulding compound thick composites. Pultruded (non-laminated) and sheet moulding compound (laminated) thick glass fibre–reinforced plastic composites with a higher percentage of fibre weight fraction are extensively used in construction of bridges, prefabricated platforms, ballistic applications, structural applications, instrument bases and automotive load floors, and therefore, prediction of better performance drill helps the fabrication industry in making good quality holes. The drilling experiments using coated tungsten carbide drills, twist drill (standard geometry) and ratio drill (special geometry) of diameter of 10 mm were conducted using response surface methodology. Analysis of variance of the experimental results reveals that for both twist drill and ratio drill, feed is more significant in influencing the quality characteristics. The experimental values obtained for quality characteristics are empirically related to process parameters by developing response surface models using Design-Expert software. Analysis of the experimental results reveals that ratio drill performs better in pultruded composites and twist drill performs better in sheet moulding compound composites. The optimal process parameter levels within the selected range for minimizing all the quality characteristics together were determined.
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CERESOLE, ANNA T., PIETRO FRÉ, FERDINANDO GLIOZZI, and STEFANO VINTI. "COMPLEX FREE FERMION SUPERSTRINGS AS GROUPFOLD COMPACTIFICATIONS." International Journal of Modern Physics A 06, no. 27 (November 20, 1991): 4843–58. http://dx.doi.org/10.1142/s0217751x9100229x.
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We consider the class of superstring vacua arising from the free fermion construction based on the SU (3) ⊗ SO (5) or SU (2) ⊗ SU (4) supercurrent. The internal free fermions have complex boundary conditions. We show that these vacua admit a geometric interpretation as compactifications on twisted WZW models.
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Geyer, B., M. Lazar, and D. Robaschik. "Erratum to: “Power corrections of off-forward quark distributions and harmonic operators with definite geometric twist”." Nuclear Physics B 652 (March 2003): 408. http://dx.doi.org/10.1016/s0550-3213(02)01142-2.
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Majeti, Rohin Kumar, and Stephan Benz. "Mission-based optimal morphing parameters for rotors with combined chord and twist morphing." Open Research Europe 1 (October 12, 2021): 121. http://dx.doi.org/10.12688/openreseurope.14060.1.
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Background: The fixed geometry rotor blades in today’s helicopters do not give the best performance throughout the duration of any mission. However, low-speed and high-speed flights have different geometrical requirements for the shape of the most efficient rotor blades. With advancements in morphing technologies, these can be applied to change the shape of the blades in different flight regimes. Methods: Two different helicopter rotor morphing concepts – namely, the linearly variable chord extension and the torque-tube based twist - under the framework of the European project SABRE were investigated for their optimal geometric parameters using a Particle Swarm Optimization (PSO) algorithm. Since the morphing parameters were dependent on the mission profile, three different missions representing typical helicopter applications were chosen. The optimization problem was posed both as single objective (power) and as multi-objective (power, tip elastic torsion and vibratory hub load). Based on the insights drawn from these investigations, a rotor was set up including both morphing concepts in a single blade. Results: The rotor with combined chord and twist morphing was shown to have better performance than the baseline blade, while keeping the penalty on the elastic torsion and vibration of the rotor to a minimum. Conclusions: Chord and twist are both important parameters determining the efficiency of a rotor blade. Since they have non-overlapping requirements, combining the two morphing concepts into a single blade can yield higher performance than the individual ones.
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Ghalambaz, Mohammad, Hayder I. Mohammed, Jasim M. Mahdi, Amir Hossein Eisapour, Obai Younis, Aritra Ghosh, Pouyan Talebizadehsardari, and Wahiba Yaïci. "Intensifying the Charging Response of a Phase-Change Material with Twisted Fin Arrays in a Shell-And-Tube Storage System." Energies 14, no. 6 (March 15, 2021): 1619. http://dx.doi.org/10.3390/en14061619.
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A twisted-fin array as an innovative structure for intensifying the charging response of a phase-change material (PCM) within a shell-and-tube storage system is introduced in this work. A three-dimensional model describing the thermal management with charging phase change process in PCM was developed and numerically analyzed by the enthalpy-porosity method using commercial CFD software. Efficacy of the proposed structure of fins for performing better heat communication between the active heating surface and the adjacent layers of PCM was verified via comparing with conventional longitudinal fins within the same design limitations of fin material and volume usage. Optimization of the fin geometric parameters including the pitch, number, thickness, and the height of the twisted fins for superior performance of the proposed fin structure, was also introduced via the Taguchi method. The results show that a faster charging rate, higher storage rate, and better uniformity in temperature distribution could be achieved in the PCMs with Twisted fins. Based on the design of twisted fins, it was found that the energy charging time could be reduced by up to 42%, and the energy storage rate could be enhanced up to 63% compared to the reference case of straight longitudinal fins within the same PCM mass limitations.
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Shen, Hui-Shen. "Post-buckling of internal-pressure-loaded laminated cylindrical shells surrounded by an elastic medium." Journal of Strain Analysis for Engineering Design 44, no. 6 (August 1, 2009): 439–58. http://dx.doi.org/10.1243/03093247jsa505.
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This paper presents a study on the post-buckling response of an anisotropic laminated cylindrical shell of finite length embedded in a large outer elastic medium and subjected to internal pressure in thermal environments. The surrounding elastic medium is modelled as a tensionless Pasternak foundation reacting in compression only. The governing equations are based on higher-order shear deformation shell theory with von Kármán–Donnell kinematic non-linearity and including extension–twist, extension–flexural, and flexural–twist couplings. The thermal effects are also included, and the material properties are assumed to be temperature dependent. Non-linear prebuckling deformations and the initial geometric imperfections of the shell are both taken into account. A singular perturbation technique is employed to determine the post-buckling response of the shells, and an iterative scheme is developed to obtain numerical results without using any assumption concerning the shape of the contact region between the shell and the elastic medium. Numerical illustrations concern the buckling and post-buckling response of cross-ply and symmetric angle-ply laminated shells surrounded by an elastic medium of tensionless foundation of the Pasternak type, from which results for conventional elastic foundations are obtained as comparators. The results reveal that unilateral constraints have a significant effect on the post-buckling response of shells subjected to internal pressure in thermal environments when the foundation stiffness is sufficiently large.
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Hernández-Comas, Brando, Daniel Maestre-Cambronel, Carlos Pardo-García, Marlen Del Socorro Fonseca-Vigoya, and Jhon Pabón-León. "Influence of Compression Rings on the Dynamic Characteristics and Sealing Capacity of the Combustion Chamber in Diesel Engines." Lubricants 9, no. 3 (March 2, 2021): 25. http://dx.doi.org/10.3390/lubricants9030025.
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Internal combustion engines are widely implemented in several applications; however, they still face significant challenges due to the sealing capacity of the compression rings. Gas leakage through the crankcase, also known as blow-by, directly impacts power losses, overall efficiency, and global emissions. Therefore, the present study investigates the influence of parameters such as the ring gap, ring masses, and twist angle of the compression rings on the sealing capacity of the combustion chamber. A mathematical model is proposed to account for geometric, dynamic, and operational characteristics in a single-cylinder diesel engine. The results indicated that the greatest gas losses to the crankcase occur during the compression and combustion stages as a consequence of extreme pressure conditions. Specifically, at least 0.5% of the gases locked in the combustion chamber are released on each cycle, while increasing the mass of the compression rings boosts the gas leakage due to higher inertial forces in the rings. In contrast, a positive twist angle of the compression rings reduced the combustion gases leakage by 7.33×10−5 g/cycle. Additionally, a combined reduction in the gap of both compression rings minimized the leakage flows by 37%. In conclusion, the proposed model served as a robust tool to evaluate different parameters on the sealing capacity of the combustion chamber that contribute to minimizing global emissions. Secondary piston motion and ring distortion represent significant opportunities in future studies.
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Ray, Suchibrata, Anindya Ghosh, and Debamalya Banerjee. "Analyzing the effect of spinning process variables on blow room blended cotton melange yarn quality." Research Journal of Textile and Apparel 22, no. 1 (March 12, 2018): 2–14. http://dx.doi.org/10.1108/rjta-05-2017-0019.
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Purpose The use and importance of mélange yarn in apparel sector is increasing day by day. With the gradual increase in market share, achieving the desired quality level of mélange yarn remains a challenge for yarn manufacturing industry. The purpose of this paper is to investigate the effect of raw material (dyed fiber percentage in the mixing), important spinning process variable (yarn twist multiplier) and productivity (spindle rpm of ring frame) on properties of cotton mélange spun yarn. Design/methodology/approach Box and Behnken Design of experiment has been used to investigate the important yarn quality parameters like evenness, imperfection, hairiness, breaking strength and breaking elongation of blow room blended cotton mélange yarn. The quadratic regression model is used to derive the statistical inferences about sensitivity of the yarn quality parameters to the different process variables. The response surfaces are constructed for depicting the geometric representation of yarn quality parameters plotted as a function of process variables. Findings The study shows that shade depth and spindle speed have significant effects on the mélange yarn unevenness and imperfections. Mélange yarn strength and hairiness are significantly affected by shade depth and yarn twist multiplier (TM). Yarn elongation at break is only influenced by the spindle speed. A darker shade is responsible for higher yarn unevenness, imperfection, hairiness and lower yarn strength. A higher spindle speed is also liable for deterioration of yarn quality. Practical implications Many spinning industries are planning to convert their existing spindles from normal gray yarn production to mélange yarn manufacturing. The outcome of this study will lead to achieve better mélange yarn quality and productivity by the industry. Originality/value Research on mélange yarn is itself scant. This study is exclusively conducted to analyze the individual and interactive effect of various process parameters on the mélange yarn quality.
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Kobelev, Vladimir. "Stability optimization for a simultaneously twisted and compressed rod." Multidiscipline Modeling in Materials and Structures 18, no. 1 (February 8, 2022): 24–42. http://dx.doi.org/10.1108/mmms-12-2021-0205.
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PurposeThe authors search the optimal distribution of bending flexure along the axis of the rod. For the solution of the actual problem, the stability equations take into account all possible convex, simply connected shapes of the cross-section. The authors study the cross-sections with equal principal moments of inertia. The cross-sections are similar geometric figures related by a homothetic transformation with respect to a homothetic center on the axis of the rod and vary along its axis. The cross-section that delivers the maximum or the minimum for the critical eigenvalue must be determined among all convex, simply connected domains. The optimal form of the cross-section is known to be an equilateral triangle. The distribution of material along the length of a twisted and compressed rod is optimized so that the rod must support the maximal moment without spatial buckling, presuming its volume remains constant among all admissible rods. The static Euler's approach is applicable for simply supported rod (hinged), twisted by the conservative moment and axial compressing force.Design/methodology/approachThe optimization problems for stability of twisted and compressed rods are studied in this manuscript. The complement for Euler's buckling problem is Greenhill's problem, which studies the forming of a loop in an elastic bar under simultaneous torsion and compression (Greenhill, 1883).FindingsFor determining the optimal solution, the authors directly compare the twisted rods with the different lengths and cross-sections using the invariant factors. The solution of optimization problem for simultaneously twisted and compressed rod is stated in closed form.Research limitations/implications(1) The linear stability equations are applied. (2) No nonlinear or postbuckling effects were accounted. (3) The moment-free, ideal boundary conditions on both ends of the rod assumed.Practical implicationsOne of the most common design cases in mechanical engineering is the concurrent compression and twisting of the straight members. The closed-form solution allows the immediate estimation of the optimization effect for axes and rotors in industrial and automotive engineering.Social implicationsThe application of lighter and material-saving structural elements allow the saving fabrication resources, reducing the mass of vehicles and industry machines. The systematic usage of material optimized structural elements assists the stabilization of global energy balance of Earth.Originality/valueAlbeit the governing ordinary differential equations are linear, the application of the optimality conditions leads to the nonlinearity of the final optimization equations. The search of closed form solution of the nonlinear differential equations is one of the mathematically hardest tasks in engineering mathematics. The closed-form solution presents in terms of higher transcendental functions.
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Hobbs, D. M., M. M. Alvarez, and F. J. Muzzio. "Mixing in Globally Chaotic Flows." Fractals 05, no. 03 (September 1997): 395–425. http://dx.doi.org/10.1142/s0218348x9700036x.
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The first half of this paper reviews mixing in chaotic flows. The sine-flow is employed as a two dimensional example to demonstrate techniques used for characterizing mixing behavior. Several manifestations of self-similarity are readily apparent. The results of tracer mixing simulations demonstrate a self-similar, iterative development of partially mixed structures in the flow. The spatial distribution of mixing intensities present in the flow is examined via computation of stretching. The probability density function (PDF) of the logarithm of stretching values reveals a Gaussian distribution over the central spectrum of stretching intensities for the globally chaotic case, but contains two peaks for a case with coexisting chaotic and regular regions: a broad Gaussian peak for higher stretching values, corresponding to the chaotic region, and a sharp peak of low stretching values corresponding to the regular regions. The self-similar stretching distributions can be collapsed to a single invariant distribution using an appropriate scaling based on the central limit theorem. The folding processes in the flow are examined through curvature calculations; PDFs for curvature collapse to time invariant self-similar distributions without the need for scaling. Direct computation of the striation thickness distribution (STD) provides the most fundamental (and computationally most expensive) measure of mixing; STDs develop a self-similar form that can be collapsed to an invariant distribution using a simple scaling. The second half of the paper focuses on a real, three-dimensional mixing system: the Kenics static mixer. Two alternate configurations of the Kenics mixer were analyzed: one in which elements have alternating right-handed and left-handed twist (R-L) and a second in which all elements have right-handed twist (R-R). Poincaré sections as well as experiments indicate that the R-L configuration is globally chaotic, while the R-R configuration contains significant segregated, regular regions. Stretching histories of material elements in the two flows were computed, once again revealing self-similar distributions that can be collapsed to an invariant limit using a scaling based on the central limit theorem.
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Nikonov, I., and G. Sharygin. "Pairings in Hopf cyclic cohomology of algebras and coalgebras with coefficients." Journal of K-Theory 5, no. 2 (March 15, 2010): 289–348. http://dx.doi.org/10.1017/is010003006jkt076.
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AbstractThis paper is concerned with the theory of cup products in the Hopf cyclic cohomology of algebras and coalgebras. We show that the cyclic cohomology of a coalgebra can be obtained from a construction involving the noncommutative Weil algebra. Then we introduce the notion of higher -twisted traces and use a generalization of the Quillen and Crainic constructions (see [14] and [3]) to define the cup product. We discuss the relation of the cup product above and S-operations on cyclic cohomology. We show that the product we define can be realized as a combination of the composition product in bivariant cyclic cohomology and a map from the cyclic cohomology of coalgebras to bivariant cohomology. In the last section, we briefly discuss the relation of our constructions with that in [9]. More precisely, we propose still another construction of such pairings which can be regarded as an intermediate step between the “Crainic” pairing and that of [9]. We show that it coincides with what in [9] and as far its relation to Crainic's construction is concerned, we reduce the question to a discussuion of a certain map in cohomology (see the question at the end of section 5).The results of the current paper were announced in [12].
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HOU, BO-YU, DAN-TAO PENG, KANG-JIE SHI, and RUI-HONG YUE. "SOLITONS ON NONCOMMUTATIVE TORUS AS ELLIPTIC CALOGERO–GAUDIN MODELS, BRANES AND LAUGHLIN WAVE FUNCTIONS." International Journal of Modern Physics A 18, no. 14 (June 10, 2003): 2477–500. http://dx.doi.org/10.1142/s0217751x03014228.
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For the noncommutative torus [Formula: see text], in the case of the noncommutative parameter [Formula: see text], we construct the basis of Hilbert space ℋn in terms of θ functions of the positions zi of n solitons. The wrapping around the torus generates the algebra [Formula: see text], which is the Zn × Zn Heisenberg group on θ functions. We find the generators g of a local elliptic su (n), which transform covariantly by the global gauge transformation of [Formula: see text]. By acting on ℋn we establish the isomorphism of [Formula: see text] and g. We embed this g into the L-matrix of the elliptic Gaudin and Calogero–Moser models to give the dynamics. The moment map of this twisted cotangent [Formula: see text] bundle is matched to the D-equation with the Fayet–Illiopoulos source term, so the dynamics of the noncommutative solitons become that of the brane. The geometric configuration (k, u) of the spectral curve det |L(u) - k| = 0 describes the brane configuration, with the dynamical variables zi of the noncommutative solitons as the moduli T⊗ n/Sn. Furthermore, in the noncommutative Chern–Simons theory for the quantum Hall effect, the constrain equation with quasiparticle source is identified also with the moment map equation of the noncommutative [Formula: see text] cotangent bundle with marked points. The eigenfunction of the Gaudin differential L-operators as the Laughlin wave function is solved by Bethe ansatz.
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Sherif, A. M., and P. K. S. Dunsby. "Conformal geometry on a class of embedded hypersurfaces in spacetimes." Classical and Quantum Gravity 39, no. 4 (January 20, 2022): 045004. http://dx.doi.org/10.1088/1361-6382/ac45db.
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Abstract In this work, we study various geometric properties of embedded spacelike hypersurfaces in 1 + 1 + 2 decomposed spacetimes with a preferred spatial direction, denoted e μ , which are orthogonal to the fluid flow velocity of the spacetime and admit a proper conformal transformation. To ensure non-vanishing and positivity of the scalar curvature of the induced metric on the hypersurface, we impose that the scalar curvature of the conformal metric is non-negative and that the associated conformal factor φ satisfies 0$?> φ ^ 2 + 2 φ ^ ^ > 0 , where * ^ denotes derivative along the preferred spatial direction. Firstly, it is demonstrated that such hypersurface is either of Einstein type or the spatial twist vanishes on them, and that the scalar curvature of the induced metric is constant. It is then proved that if the hypersurface is compact and of Einstein type and admits a proper conformal transformation, then these hypersurfaces must be isomorphic to the three-sphere, where we make use of some well known results on Riemannian manifolds admitting conformal transformations. If the hypersurface is not of Einstein type and have nowhere vanishing sheet expansion, we show that this conclusion fails. However, with the additional conditions that the scalar curvatures of the induced metric and the conformal metric coincide, the associated conformal factor is strictly negative and the third and higher order derivatives of the conformal factor vanish, the conclusion that the hypersurface is isomorphic to the three-sphere follows. Furthermore, additional results are obtained under the conditions that the scalar curvature of a metric conformal to the induced metric is also constant. Finally, we consider some of our results in context of locally rotationally symmetric spacetimes and show that, if the hypersurfaces are compact and not of Einstein type, then under specified conditions the hypersurface is isomorphic to the three-sphere, where we constructed explicit examples of proper conformal Killing vector fields along e μ .
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MARZOUK, S. S., A. S. GENDY, S. N. MIKHAIEL, and A. F. SALEEB. "MODELING WITH INCREASED EFFICIENCY AND VERSATILITY FOR FLEXURAL-TORSIONAL BUCKLING OF UNSYMMETRICAL THIN-WALLED STRUCTURES." International Journal of Structural Stability and Dynamics 02, no. 04 (December 2002): 431–56. http://dx.doi.org/10.1142/s0219455402000658.
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Aiming at the performance-enhancement in coarse mesh modeling, we utilize a number of closed form solutions of a class of torsionally loaded thin-walled bars to formulate a two-noded element for spatial buckling analysis. The key in this relates to the use of the "exact" solution for the displacement fields (as oppose to the more conventional finite element approach where polynomial/Lagrangian-type interpolation is employed). That is, in addition to the well known "exact" solution for the coupled flexure/transverse-shear problem, we utilize a new "exact" solution for the more difficult case of coupled system of differential equations governing a torsionally loaded thin-walled beam using the higher-order theories of non-uniform twist/bi-moment with coupled warping-shear deformations. For the linear analysis, convergence and accuracy study indicated that the proposed model to be rapidly convergent, stable and computationally efficient; i.e. one element is sufficient to exactly represent an end loaded part of the beam. Such model has been extended to account for nonlinear analysis, in particular, the flexural torsional buckling of thin-walled structures. To this end, the effect of finite rotations in space is accounted for as per the modern theories of spatial buckling, resulting in second-order accurate geometric stiffness matrices. Compared with the classical theory of thin-walled structures, the present approach is more general in that all significant modes of stretching, bending, shear (due to both flexure and torsional/warping), torsion, and warping are accounted for. The inclusion of non-uniform torsion is accomplished through adoption of the principle sectorial area. This requires incorporation of a warping degree of freedom in addition to the conventional six degrees of freedom at each node. The element is derived for general cross sections including the Wagner-effect contributions. The model's properties and performance, particularly with regard to the resulting (significant) improvements in mesh accuracy, are assessed in a fairly complete set of numerical simulations.
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Лось, Александр Васильевич, Владимир Федорович Шмырев, and Виктор Иванович Рябков. "ДОСТИЖЕНИЕ ПРЕИМУЩЕСТВА Ан-188 СРЕДИ ОПЕРАТИВНО–ТАКТИЧЕСКИХ ВОЕННО-ТРАНСПОРТНЫХ САМОЛЕТОВ." Aerospace technic and technology, no. 8 (August 31, 2020): 5–11. http://dx.doi.org/10.32620/aktt.2020.8.01.
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In the "Antonov" Company, a unique medium-sized tactical military transport aircraft An-12 and An-70 have been created. Based on the Аn-12 basic version, several modifications have been developed, which operate in many countries around the world.To replace this aircraft has been created the An-70 with a higher capacity and hourly capacity, which on some key parameters outperforms the competition-analogs: American C-130J-30, West-European A400M, and Japanese C-2.However, the range with the maximum capacity is worse for Аn-77 compared to the A400M, but cruising speed and combat readiness – for C-2.For the most complete implementation of tactical tasks:– transportation of personnel, equipment, goods, and means of procurement;– delivery of military units, equipment, and cargo in the interests of peacekeeping or counter-terrorism operations;– transportation of troops, arms, military equipment and material resources of strategic direction;– delivery of units and formations of the airborne forces and ground forces in the areas of military purpose;– provision of the relocation of aviation units and formations, and provision of superiority at range with maximum load, at cruising speed and combat readiness the team of the “Antonov” Company created the An-188 – the medium-sized tactical aircraft with short takeoff and landing, which provides execution of a series of tasks, not available even for C-2.At the initial stage of designing this modification scientific principles the "Design techniques of modifications of the MTA taking into account the profound changes in the wing and the power plant" were used. The most important modification change in An-188 is the replacement of the D-27 turboprop engine for СFM LЕАР-1A turbofan engine, which increased the capacity and combat readiness of modification.Another important modification change was the use of discrete geometric twist of the wing local chord, bringing its shape in plan view to elliptical one and has brought a reduction in induced drag for a given lift force. This solution provided an increase in the range of up to 3200 km.Such profound modification changes in the power plant and the geometry of the wing have contributed to the complete superiority of the An-188 in the class of operational-tactical MTA.In combination with An-132D and An-178 modification, the An-188 can be considered as a unified system of support for the troops with military transport planes.
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Лось, Олександр Васильович, and Віктор Іванович Рябков. "НОВЕ ПОКОЛІННЯ ВІТЧИЗНЯНИХ ВІЙСЬКОВО-ТРАНСПОРТНИХ ЛІТАКІВ." Aerospace technic and technology, no. 4 (August 28, 2020): 5–11. http://dx.doi.org/10.32620/aktt.2020.4.01.
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According to European experts, only the USA and Ukraine can produce a full line of military transport aircraft of all weight categories (light, medium, and heavy).At the time of the creation of the “State comprehensive program for the development of the aviation industry of Ukraine until 2020” Ukraine had:- light transport aircraft An-32 with a carrying capacity of 6.7 tons and a range of 2500 km;- operational and tactical military passenger aircraft (MPA) with a carrying capacity of 30 tons and a range with a full load of 4300 km;- regional passenger aircraft Аn-148-100В (An-148-100V) with a maximum payload of 9.0 tons and a range of 2600 km.Through the efforts of the entire Antonov Company team, prototypes have been designed, manufactured, and partly tested such modifications as An-132D, An-178, and An-188, the implementation of which is based on the use of the new “Methodology for Designing Military Transport Aircraft Modifications, Taking into Account Profound Changes in the Wing and in the Power Plant”.Given the scientific provisions of this "Methodology ...":- based on the An-32 aircraft, a modification of the light aircraft MTA An-132D with a carrying capacity of 9.1 tons, with an increased range of up to 2400 km and with a fuel efficiency index higher than that of the base model, has been created through profound changes in the power plant, i.e. using PW150 engines and an increase in fuel mass by one and a half times;- based on the An-148 passenger aircraft, by means of profound changes both in the wing geometry and in the power plant, a modification of the mid-range military transport An-178 aircraft has been created with a carrying capacity of 18 tons and a range with a maximum load of 1.200 km, which provides a niche to this modification not occupied by competitors;- ensuring the complete superiority of the An-188 modification among analog competitors is also based on the profound changes: replacement the D27 turboprop engine for a turbofan CFM LEAP-1Ain the power plant; the use of a discrete geometric twist of the local wing chords, which ensured the aircraft range of 3200 km with a payload of 47 tons and significantly increased its combat readiness due to the use of turbofan engines.A comparative assessment of these military transport aircraft with their basic models shows that the team of the Antonov Company has honorably implemented the “State comprehensive program for the development of the aviation industry of Ukraine until 2020” in part of the creation of a new generation of military transport aircraft that is competitive in all technical and economic parameters.
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Xu, Duo, Chong Gao, Hang Fan, Wangwang Yang, Jian Fang, Keshuai Liu, and Weilin Xu. "The relevance of false-twist addition on ring spun yarns by means of rotary threaded surfaces." Textile Research Journal, January 13, 2022, 004051752110639. http://dx.doi.org/10.1177/00405175211063908.
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A novel concept of producing false-twist yarns by cyclical stress fluctuation was developed. The forming principle was introduced to analyze the formation process of false twists on rotary threaded contact surfaces. Geometric analysis indicates that cyclical stress variations produce extra rotations (false twists) on fiber strands in the yarn formation area, causing twist redistribution and fiber arrangement remodeling with the appearance of local fiber reversion. Theoretical analysis reveals that more false twists are produced when the spun yarn is in contact with surfaces of high traverse speeds. Then, a motion simulation model using different traverse speeds of the threaded contact surface was established to compare the yarn internal stress variation, verifying the false-twist efficiency at different traverse speeds. Finally, a systematic comparison was conducted between the yarns spun at different traverse speeds. It was shown that the yarn properties improved with higher traverse speeds of the threaded contact surface, achieving less hairiness, high yarn strength, and low residual torque.
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Guignard, Quentin. "GEOMETRIC LOCAL -FACTORS IN HIGHER DIMENSIONS." Journal of the Institute of Mathematics of Jussieu, September 2, 2021, 1–27. http://dx.doi.org/10.1017/s1474748021000037.
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Abstract We prove a product formula for the determinant of the cohomology of an étale sheaf with $\ell $ -adic coefficients over an arbitrary proper scheme over a perfect field of positive characteristic p distinct from $\ell $ . The local contributions are constructed by iterating vanishing cycle functors as well as certain exact additive functors that can be considered as linearised versions of Artin conductors and local $\varepsilon $ -factors. We provide several applications of our higher dimensional product formula, such as twist formulas for global $\varepsilon $ -factors.
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Ismail, N. I., A. H. Zulkifli, M. Hisyam Basri, R. J. Talib, and Mahadzir M. M. Mahadzir M.M. "LOCAL ANGLE OF ATTACK EXTRACTION METHOD FOR TWIST MORPHING MAV WING." Jurnal Teknologi 75, no. 8 (August 20, 2015). http://dx.doi.org/10.11113/jt.v75.5207.
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The geometric twist characteristic on twist morphing MAV wing has significant influence on its aerodynamic performances. Higher geometric twist magnitude induces higher lifts and drags generation. However, in order to determine the geometric twist performance, a detail analysis has to be carried out to extract the local angle of attack (AOA) value on each wing cross section. Thus, current works introduces a new method in extracting the local AOA value on a twist morphing MAV wing. The method manipulates the automated coordinate generation produced by Ansys software and combined the generated coordinates with manual determination of local AOA magnitude. Based on the analysis executed on a twist morphing wing sample, 30 local AOA values were obtained from 30 wing cross sections. By using the local AOA value at the root chord and wing tip, the geometric twist magnitude or twist intensity for a twist morphing wing is determined. Based on a selected twist morphing MAV wing sample, the local AOA extraction method able to calculate the wing geometric twist at ϵ = 12.5°.
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Satoh, Yuji, and Yuji Sugawara. "Interactions of strings on a T-fold." Journal of High Energy Physics 2022, no. 6 (June 2022). http://dx.doi.org/10.1007/jhep06(2022)121.
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Abstract We consider the interactions of strings on T-folds from the world-sheet point of view which are exact in α′. As a concrete example, we take a model where the internal torus at the SO(8) enhancement point is twisted by T-duality (T-folded), and compute the scattering amplitudes of a class of massless strings. The four-point amplitudes involving both twisted and untwisted strings are obtained in a closed form in terms of the hyper- geometric function. By their factorization, the three-point coupling of the twisted and untwisted strings is found to be suppressed by the chiral momenta along the internal torus, and quantized in integer powers of 1/4. The asymptotic forms of the four-point amplitudes in high-energy limits are also obtained. Our results rely only on general properties of the asymmetric orbifold by the T-duality twist and of the Lie algebra lattice from the symmetry enhancement, and thus may be extended qualitatively to more general T-folds.
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Geyer, Bodo, and Oliver Witzel. "B-meson distribution amplitudes of geometric twist versus dynamical twist." Physical Review D 72, no. 3 (August 24, 2005). http://dx.doi.org/10.1103/physrevd.72.034023.
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Mishra, Rama, and Ross Staffeldt. "Polynomial invariants, knot homologies, and higher twist numbers of weaving knots W(3,n)." Journal of Knot Theory and Its Ramifications, May 31, 2021, 2150025. http://dx.doi.org/10.1142/s0218216521500255.
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We investigate several conjectures in geometric topology by assembling computer data obtained by studying weaving knots, a doubly infinite family [Formula: see text] of examples of hyperbolic knots. In particular, we compute some important polynomial knot invariants, as well as knot homologies, for the subclass [Formula: see text] of this family. We use these knot invariants to conclude that all knots [Formula: see text] are fibered knots and provide estimates for some geometric invariants of these knots. Finally, we study the asymptotics of the ranks of their Khovanov homology groups. Our investigations provide evidence for our conjecture that asymptotically as [Formula: see text] grows large, the ranks of Khovanov homology groups of [Formula: see text] are normally distributed.
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Singh, S. K., A. Kumar, P. Singh, and A. K. Ansu. "Experimental Analysis of Double Pipe Heat Exchanger with V-cut Twisted Tape Inserts using PCM Dispersed Nanofluids." International Journal of Vehicle Structures and Systems 14, no. 2 (March 8, 2022). http://dx.doi.org/10.4273/ijvss.14.2.09.
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The performance of a double tube heat exchanger with V-cut twisted tape inserts (VCTT) and phase change material (PCM) dispersed nanofluid is investigated experimentally. The three water-based Al2O3, PCM, and Al2O3+PCM nanofluid with different concentrations (0.01-0.1% vol.) are used. The impacts of different geometric parameters, i.e., twist ratio (TR), depth ratio (DR) and width ratio (WR) of VCTT inserts on Nusselt number (Nu), friction factor (f) and entropy generation are examined. The outcomes expose that Nu and f increase as particle concentration increases and twisting ratio decreases. A higher Nu and f are generated by a higher DR or a lower WR. In all cases, the entropy generation of nanofluid is found to be lower than that of water. For all working fluids, a rise in TR, a fall in DR, and a rise in WR increases overall entropy generation.
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BERGNER, HANNAH, and PATRICK GRAF. "THE LIPMAN–ZARISKI CONJECTURE IN GENUS ONE HIGHER." Forum of Mathematics, Sigma 8 (2020). http://dx.doi.org/10.1017/fms.2020.19.
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We prove the Lipman–Zariski conjecture for complex surface singularities with $p_{g}-g-b\leqslant 2$ . Here $p_{g}$ is the geometric genus, $g$ is the sum of the genera of exceptional curves and $b$ is the first Betti number of the dual graph. This improves on a previous result of the second author. As an application, we show that a compact complex surface with a locally free tangent sheaf is smooth as soon as it admits two generically linearly independent twisted vector fields and its canonical sheaf has at most two global sections.
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Hollands, Lotte, Philipp Rüter, and Richard J. Szabo. "A geometric recipe for twisted superpotentials." Journal of High Energy Physics 2021, no. 12 (December 2021). http://dx.doi.org/10.1007/jhep12(2021)164.
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Abstract We give a pedagogical introduction to spectral networks and abelianization, as well as their relevance to $$ \mathcal{N} $$ N = 2 supersymmetric field theories in four dimensions. Motivated by a conjecture of Nekrasov-Rosly-Shatashvili, we detail a geometric recipe for computing the effective twisted superpotential for $$ \mathcal{N} $$ N = 2 field theories of class $$ \mathcal{S} $$ S as a generating function of the brane of opers, with respect to the spectral coordinates found from abelianization. We present two new examples, the simplest Argyres-Douglas theory and the pure SU(2) gauge theory, while we conjecture the E-expansion of the effective twisted superpotential for the E6 Minahan-Nemeschansky theory.
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Uhlemann, Christoph F. "Information transfer with a twist." Journal of High Energy Physics 2022, no. 1 (January 2022). http://dx.doi.org/10.1007/jhep01(2022)126.
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Abstract Holographic duals for CFTs compactified on a Riemann surface Σ with a twist are cast in the language of wedge holography. Σ starts as part of the field theory geometry in the UV and becomes part of the internal space in the IR. This allows to associate entanglement entropies with splits of the internal space in the IR geometry. Decomposing the internal space in the IR and geometrizing the corresponding subsystems separately leads to two interacting gravitational systems, similar to the intermediate holographic description in braneworld models. For Σ = T2 the setups are used to model information transfer from a black hole to a gravitating bath. This leads to Page curves with a phase structure which precisely mirrors that in braneworld models. The transition from geometric to non-geometric entropies is also discussed for Σ = S2 as a model for more general internal spaces in AdS/CFT.
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Bhardwaj, Lakshya, Patrick Jefferson, Hee-Cheol Kim, Houri-Christina Tarazi, and Cumrun Vafa. "Twisted circle compactifications of 6d SCFTs." Journal of High Energy Physics 2020, no. 12 (December 2020). http://dx.doi.org/10.1007/jhep12(2020)151.
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Abstract We study 6d superconformal field theories (SCFTs) compactified on a circle with arbitrary twists. The theories obtained after compactification, often referred to as 5d Kaluza-Klein (KK) theories, can be viewed as starting points for RG flows to 5d SCFTs. According to a conjecture, all 5d SCFTs can be obtained in this fashion. We compute the Coulomb branch prepotential for all 5d KK theories obtainable in this manner and associate to these theories a smooth local genus one fibered Calabi-Yau threefold in which is encoded information about all possible RG flows to 5d SCFTs. These Calabi-Yau threefolds provide hitherto unknown M-theory duals of F-theory configurations compactified on a circle with twists. For certain exceptional KK theories that do not admit a standard geometric description we propose an algebraic description that appears to retain the properties of the local Calabi-Yau threefolds necessary to determine RG flows to 5d SCFTs, along with other relevant physical data.
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Song, Shaokang, Xiang Cheng, Ming Shi, Guangming Zheng, Ruichun Dong, and Zonggao Mu. "Study of the burr height at hole exit in bone drilling by twist drills." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine, September 18, 2022, 095441192211241. http://dx.doi.org/10.1177/09544119221124170.
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The burr at the hole exit is one of the key factors affecting bone drilling performances. In order to reduce burr height at hole exit during cortical bone drilling, the four key parameters in twist drilling of bones are analyzed based on the response surface method (RSM). The prediction model of the burr height is obtained via the analysis of variance. The influence trend and size of each factor on the height of the burr are further analyzed based on the RSM. Experimental results show that smaller point angle and diameter of the twist drill, smaller feed speed, and higher rotational speed can effectively reduce the burr height at hole exit. Then, the geometric variables of the twist drill and process parameters are optimized. When the point angle of the twist drill 2 Φ = 95°, the diameter D = 2.5 mm, the rotational speed n = 1500 rpm, and the feed speed vf = 10 mm/min, the height of the burr at hole exit reaches the smallest. At the same time, the burr at the exit of the hole with different diameters of twist drills is studied. It is found to be beneficial to select a twist drill with a smaller diameter for drilling when the requirements of drilling are fulfilled.
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Eilers, Jörg, Bodo Geyer, and Markus Lazar. "Geometric twist decomposition off the light cone for nonlocal QCD vector operators." Physical Review D 69, no. 3 (February 26, 2004). http://dx.doi.org/10.1103/physrevd.69.034015.
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Solowjowa, N., D. Zimpfer, M. Mueller, H. Krastev, V. Falk, T. H. Schloeglhofer, C. H. Starck, E. Potapov, and I. Netuka. "P819 Outflow graft twist occlusion in the heartmate 3 left ventricular assist system in 7 cases: analysis of potential mechanisms using computed tomography." European Heart Journal - Cardiovascular Imaging 21, Supplement_1 (January 1, 2020). http://dx.doi.org/10.1093/ehjci/jez319.471.
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Abstract Background Twist of the outflow graft (OG) of the HeartMate 3 left ventricular (LV) assist device (HM3) with subsequent occlusion is a rare, but life-threatening complication. Purpose We evaluated if potential implantation technique dependent mechanisms of OG twist can be predicted by multislice computed tomography (MSCT). Methods We retrospectively analyzed clinical, echocardiographic and MSCT data of 7 patients with angiographically proven and surgically corrected OG twist and of 11 consecutive patients without any type of pump obstruction. MSCT parameters were: position of inflow cannula related to anatomical LV apex (1), angulation of axis of inflow cannula related to LV axis (2), orientation of outflow channel of the pump housing related to LV axis (3), OG course (4). Echocardiographic parameters were LV end-diastolic diameter (LVEDD) and aortic valve opening. Results Mean time from implantation to twist was 563 ± 161 days. Preoperative LVEDD (64.6 ± 9.8 mm vs. 67.4 ± 10.2 mm, p = 0.563) was similar. LVEDD reduction after implantation (20% vs. 28%) and prevalence of aortic valve opening was higher in the twist group (71% vs. 45%). The MSCT measurements showed a high degree of heterogeneity in both groups: (1) differed from superior to infero-lateral; (2) varied from cranial to caudal, lateral and medial; (3) varied from antero-septal to inferior. (4) showed an incidence of non-obstructive kinking of 29% and 36%, respectively. Conclusion Marked heterogeneity of the measured MSCT parameters was observed in both groups. No specific pattern or geometric relation could be attributed to the OG twist phenomenon.
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Bullimore, Mathew, Andrea E. V. Ferrari, Heeyeon Kim, and Guangyu Xu. "The twisted index and topological saddles." Journal of High Energy Physics 2022, no. 5 (May 2022). http://dx.doi.org/10.1007/jhep05(2022)116.
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Abstract The twisted index of 3d $$ \mathcal{N} $$ N = 2 gauge theories on S1× Σ has an algebro-geometric interpretation as the Witten index of an effective supersymmetric quantum mechanics. In this paper, we consider the contributions to the supersymmetric quantum mechanics from topological saddle points in supersymmetric localisation of abelian gauge theories. Topological saddles are configurations where the matter fields vanish and the gauge symmetry is unbroken, which exist for non-vanishing effective Chern-Simons levels. We compute the contributions to the twisted index from both topological and vortex-like saddles points and show that their combination recovers the Jeffrey-Kirwan residue prescription for the twisted index and its wall-crossing.
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Andriot, David, and André Betz. "Supersymmetry with non-geometric fluxes, or a β-twist in Generalized Geometry and Dirac operator." Journal of High Energy Physics 2015, no. 4 (April 2015). http://dx.doi.org/10.1007/jhep04(2015)006.
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Geyer, B., and O. Witzel. "Heavy meson distribution amplitudes of definite geometric twist with contribution of 3-particle distribution amplitudes." Physical Review D 76, no. 7 (October 18, 2007). http://dx.doi.org/10.1103/physrevd.76.074022.
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