A fast and stable first-order method for simulation of flexible beams and cables

Nonlinear Dynamics - Gradient deficient beam elements (commonly known as cable elements in the literature) based on the absolute nodal coordinate formulation (ANCF) have great potential for...     

Experimental Evaluation of the Influence of the Seawater Characteristics on Spatial and Temporal Variations of the Sound Speed in the Southern Abyssal,Intermediate and Shelf Zones of the Caspian Sea

Acoustical Physics - The results of the evaluation on the spatial and temporal changes of the underwater sound speed in the southern abyssal zone of the Caspian Sea are investigated. Experimental...     

Simplicial join via tensor product

Let be a field, and M and N two finitely generated graded modules over standard graded -algebras A and B, respectively. We will study generalized, sequentially, almost, and approximately Cohen–Macaulay as well as clean, and pretty clean properties of the -module through the corresponding properties of M and N. The behavior of these properties with respect to the simplicial join of two simplicial (multi)complexes will be revealed as corollaries.     

Design and construction of hot limiter biasing system for the tokamak

A hot limiter biasing system with a simplified fast switch circuit was designed, constructed, and installed on the IR-T1 tokamak, and then the negative voltage applied to a hot limiter inserted inside the tokamak fixed limiter and the plasma current, poloidal, and radial components of the magnetic fields, loop voltage, diamagnetic flux, and the ion saturation currents in the absence and presence of the biased limiter were measured. Results of measurements of biasing effects on the plasma equilibrium behavior and edge plasma rotation are compared and discussed.     

On (Strongly) Gorenstein Von Neumann Regular Rings

In this article, we introduce and study the rings over which every module is (strongly) Gorenstein flat, which we call them (strongly) Gorenstein Von Neumann regular rings.     

Tensor and Torsion Products of Relative Injective Modules with Respect to a Semidualizing Module

Let R be a commutative Cohen–Macaulay ring, and let C be a semidualizing module of R. In this paper, we show that C is generically dualizing if and only if the tensor products of injective and C-injective R-modules are injective. This leads to a characterization of dualizing modules as well as generalizes a result of Enochs and Jenda.     

Matter stability in modified teleparallel gravity

We study the matter stability in modified teleparallel gravity or f(T)$f(T)$ theories. We show that there is no Dolgov–Kawasaki instability in these types of modified teleparallel gravity theories. This gives for the f(T)$f(T)$ theories a great advantage over their f(R)$f(R)$ counterparts because from the stability point of view there isn?t any limit on the form of functions that can be chosen.     

Low irradiance background limited type-II superlattice MWIR M-barrier imager

We report a type-II superlattice mid-wave infrared 320×256 imager at 81 K with the M-barrier design that achieved background limited performance (BLIP) and ～99% operability. The 280 K blackbody's photon irradiance was limited by an aperture and a band-pass filter from 3.6 μm to 3.8 μm resulting in a total flux of ～5×10(12) ph.cm(-2).s(-1). Under these low-light conditions, and consequently the use of a 13.5 ms integration time, the imager was observed to be BLIP thanks to a ～5 pA dark current from the 27 μm wide pixels. The total noise was dominated by the photon flux and read-out circuit which gave the imager a noise equivalent input of ～5×10(10) ph.cm(-2).s(-1) and temperature sensitivity of 9 mK with F/2.3 optics. Excellent imagery obtained using a 1-point correction alludes to the array's uniform responsivity.     

Application of piezoelectric actuation to regularize the chaotic response of an electrostatically actuated micro-beam

The impetus of this study is to investigate the nonlinear chaotic dynamics of a clamped–clamped micro-beam exposed to simultaneous electrostatic and piezoelectric actuation. The micro-beam is sandwiched with piezoelectric layers throughout its length. The combined DC and AC electrostatic actuation is imposed on the micro-beam through two upper and lower electrodes. The piezoelectric layers are actuated via a DC electric voltage applied in the direction of the height of the piezoelectric layers, which produces an axial force proportional to the applied DC voltage. The governing differential equation of the motion is derived using Hamiltonian principle and discretized to a nonlinear Duffing type ODE using Galerkin method. The governing ODE is numerically integrated to get the response of the system in terms of the governing parameters. The results show that the response of the system is greatly affected by the amounts of DC and AC electrostatic voltages applied to the upper and lower electrodes. The results show that the response of the system can be highly nonlinear and in some regions chaotic. Evaluating the K–S entropy of the system, based on several initial conditions given to the system, the chaotic response is distinguished from the periodic or quasiperiodic ones. The main objective is to passively control the chaotic response by applying an appropriate DC voltage to the piezoelectric layers.