Search results for "Linder"

An experimental investigation on two different methods for swirl induction in a multivalve engine

2005

This paper describes an experimental investigation aimed at comparing the swirl effect induced by unbalancing the mass flow through the two intake ports of a multivalve engine head using two different methods: the first one reduced the curtain area of one of the intake valves [different lifts (DL) method]; the second one adopted a sluice-gate-shaped valve, installed upstream of the intake valves [swirl control valve (SCV) method] in order to cause a pressure drop. A steady-flow test rig (equipped with instrumentation for the discharge coefficient and swirl intensity measurement) was realized in order to compare and evaluate the results of both methods and determine their respective validit…

Onset of convective rolls in a circular porous duct with external heat transfer to a thermally stratified environment

2011

A horizontal circular duct filled with a fluid saturated porous medium is studied. The external wall is assumed to exchange heat with an external environment thermally stratified in the vertical direction. The external heat transfer is modeled through a third kind boundary condition, and a Biot number associated with the external heat transfer coefficient is defined. The linear stability of the basic state where the velocity field is zero is studied numerically. The condition of neutral stability is determined, by solving the system of elliptic governing equations for the disturbances through a Galerkin finite-element method. The neutral stability curves, together with the critical values o…

Onset of convection in a vertical porous cylinder with a permeable and conducting side boundary

2015

Abstract The onset of natural convection in a vertical porous cylinder saturated by a fluid is studied. The lateral confinement of the porous cylinder is due to an external porous medium having a permeability much smaller than that of the cylinder. Thus, the vertical side boundary of the cylinder is permeable and constrained by given pressure and temperature distributions. The lower and upper plane boundaries of the cylinder are impermeable walls. The lower wall is subject to a uniform heat flux, while the upper wall has a uniform temperature. The basic motionless state displays a uniform and vertical temperature gradient oriented downward. The linear stability analysis is carried out by us…

Numerical and Experimentical Study of Motion Control Using Pressure Feedback

2013

This paper is concerned with the inherent oscillatory nature of pressure compensated motion control of a hydraulic cylinder subjected to a negative load and suspended by means of an overcenter valve. A pressure feedback scheme that indirectly eliminates the oscillations is investigated. The indirect control scheme utilizes pressure feedback to electronically compensate the metering-out allowing for the removal of the compensator and, subsequently, elimination of the oscillations. The suggested electronic compensation scheme is implemented and examined in a single degree-of-freedom test rig actuated by means of a double acting hydraulic cylinder. The control scheme is compared with other con…

Effectiveness of BFRP confinement on the compressive behaviour of clay brick masonry cylinders

2020

Abstract This paper presents the results of an experimental and analytical study on the compressive behaviour of small clay brick masonry cylinders reinforced with a basalt fibre reinforced polymer (BFRP) composite. Fourteen cylinders, manufactured using two assembling schemes and confined using either one or two layers of BFRP grids, were tested under monotonic compression loading. Traditional strain measuring systems were integrated with digital image correlation (DIC) technique. The BFRP confined masonry cylinders showed a ductile behaviour characterised by a softening branch of the stress–strain curve. The experimental strains, strength, and full stress–strain curves were modelled using…

'Naughty cylinder' mechanical paradox

2013

A third integrating factor for indefinite integrals of special functions

2020

An integrating factor f ~ x is presented involving the terms in y ′ ′ x and q x y x of the general homogenous second-order linear ordinary differential equation. The new integrating factors obey se...

Subwavelength Bessel beams in wire media

2013

Recent progress is emerging on nondiffracting subwavelength fields propagating in complex plasmonic nanostructures. In this paper, we present a thorough discussion on diffraction-free localized solutions of Maxwell’s equations in a periodic structure composed of nanowires. This self-focusing mechanism differs from others previously reported, which lie on regimes with ultraflat spatial dispersion. By means of the Maxwell–Garnett model, we provide a general analytical expression of the electromagnetic fields that can propagate along the direction of the cylinder’s axis, keeping its transverse waveform unaltered. Numerical simulations based on the finite element method support our analytical a…

Constructive proofs of representation theorems in separable Hilbert space

1964

Vibrations of a continuous web on elastic supports

2017

We consider an infinite, homogenous linearly elastic beam resting on a system of linearly elastic supports, as an idealized model for a paper web in the middle of a cylinder-based dryer section. We obtain closed-form analytical expressions for the eigenfrequencies and the eigenmodes. The frequencies increase as the support rigidity is increased. Each frequency is bounded from above by the solution with absolutely rigid supports, and from below by the solution in the limit of vanishing support rigidity. Thus in a real system, the natural frequencies will be lower than predicted by commonly used models with rigid supports. peerReviewed