Search results for " Torsion."

Plastic yielding of glass in high-pressure torsion apparatus

2018

International audience; Hardness measurements performed at room temperature have demonstrated that glass can flow under elevated pressure, whereas the effect of high pressure on glass rheology remains poorly quantified. Here, we applied a high-pressure torsion (HPT) apparatus to deform SCHOTT SF6 â glass and attempted to quantify the effect of pressure and temperature on the shear deformation of glass subjected to pressures from 0.3 GPa to 7 GPa and temperatures from 25 ℃ to 496 ℃. Results show that the plastic yield deformation was occurring during the HPT experiments on the SF6 glass at elevated temperature from 350 ℃ to 496 ℃. The yield stress of SF6 glass decreases with increasing tempe…

Biomechanics and functional morphology of a climbing monocot.

2015

Climbing monocots can develop into large bodied plants despite being confined by primary growth. In our study on Flagellaria indica we measured surprisingly high stem biomechanical properties (in bending and torsion) and we show that the lack of secondary growth is overcome by a combination of tissue maturation processes and attachment mode. This leads to higher densities of mechanically relevant tissues in the periphery of the stem and to the transition from self-supporting to climbing growth. The development of specialised attachment structures has probably underpinned the evolution of numerous other large bodied climbing monocot taxa.

Wulff shape characterizations in overdetermined anisotropic elliptic problems

2017

We study some overdetermined problems for possibly anisotropic degenerate elliptic PDEs, including the well-known Serrin's overdetermined problem, and we prove the corresponding Wulff shape characterizations by using some integral identities and just one pointwise inequality. Our techniques provide a somehow unified approach to this variety of problems.

Introduction to Homotopy Theory

2001

Consider two manifolds X and Y together with a set of continuous maps f, g,... $$ f:X \to Y,x \to f(x) = y;x \in X,y \in Y. $$

Complex analysis for the solution of torsion problems: a comparison among three methods

2009

Influence of secondary torsion on curved steel girder bridges with box and I-girder cross-sections

2015

Steel curved girder bridges are largely used today in motorways and railways. They are often composed of thin-walled crosssections, entirely made of steel or with an upper concrete slab. The deck may have I-girders or box cross-sections: in any case curved girders are subjected to twisting moment, associated with bending, even for dead loads. Moreover, in thin-walled sections the influence of non-uniform torsion becomes sizable with respect to Saint Venant torsion, modifying the state of tangential stresses in the section and introducing axial stresses due to warping being prevented. Open sections of I-girder bridges are especially subject to these phenomena and warping can be significant n…

Moduli spaces of quasitrivial sheaves on the three dimensional projective space

2022

Let M(r,c_1,c_3,c_3) denote the Gieseker--Maruyama moduli space of semistable rank r sheaves on P^3 with the first, second and third Chern classes equal to c_1, c_2 and c_3, respectively. Maruyama proved that the space M(r,c_1,c_3,c_3) is a projective scheme. However, the geometry of such a scheme remains largely unknown, despite the efforts of many authors in the past four decades, and questions about connectedness, irreducibility, the number of irreducible components, and so on, remain open.When r=1 and c_1=0 (which can always be achieved after twisting by an appropriate line bundle), one gets that M(1,0,c_2,c_3) is isomorphic to the Hilbert scheme Hilb^{d,g}(P^3) of 1-dimensional schemes…

Comparison among three boundary element methods for torsion problems: CPM, CVBEM, LEM

2011

This paper provides solutions for De Saint-Venant torsion problem on a beam with arbitrary and uniform cross-section. In particular three methods framed into complex analysis have been considered: Complex Polynomial Method (CPM), Complex Variable Boundary Element Method (CVBEM) and Line Element-less Method (LEM), recently proposed. CPM involves the expansion of a complex potential in Taylor series, computing the unknown coefficients by means of collocation points on the boundary. CVBEM takes advantage of Cauchy’s integral formula that returns the solution of Laplace equation when mixed boundary conditions on both real and imaginary parts of the complex potential are known. LEM introduces th…

Experimental Testicular Torsion: Effect on Endocrine and Exocrine Function and Contralateral Testicular Histology

1988

In order to investigate whether unilateral testicular torsion exerts a negative influence on the previously undisturbed contralateral side, exocrine and endocrine testicular function were evaluated before and two months after torsion. A rat model with 6 hours', 12 hours' or permanent extravaginal 540 degrees torsion of the right testis was used; a sham operated group of animals served as controls. Ejaculates were collected by electrostimulation; LH, FSH and testosterone serum levels were determined by radioimmunoassays. Eight weeks after torsion sperm output had decreased by half in the experimental groups, and LH levels increased significantly, whereas the other hormone levels, as well as …

Familial Mediterranean fever as an unusual cause of acute scrotum.

2001

Correct preoperative diagnosis is the crucial step in the management of acute scrotum. With the adjunct of color Doppler ultrasound, torsion of testicular appendages, epidydimitis and orchitis as the more common nonsurgical causes are differentiated reliably from testicular torsion or incarcerated inguinal hernia. Less frequently, acute scrotal swelling is the initial symptom of systemic disorders. Leukemic infiltration of the testis or scrotal involvement in vasculitis