نتایج جستجو برای: random vibrations

تعداد نتایج: 299234  

2003
L. Polley

Tunnel amplitudes of molecular configurations (like neuronal channel pores) may be very sensitive to thermal vibrations of the barrier width (vibration-assisted tunneling) resulting in pseudo-random spikes of widely varying sizes. An observer who “lives” behind the barrier would experience as an “event” an accidental minimum of the barrier width, the timing being determined by the microstate of...

2003
S. Ciliberti T. S. Grigera

Despite the presence of topological disorder, phonons seem to exist also in glasses at very high frequencies (THz) and they remarkably persist into the supercooled liquid. A universal feature of such a systems is the Boson peak, an excess of states over the standard Debye contribution at the vibrational density of states. Exploiting the euclidean random matrix theory of vibrations in amorphous ...

2001
J. LIPSKI K. ZALESKI

The problem of stability in the machining processes is an important task. It is strictly connected with the final quality of a product. In this paper we consider vibrations of a tool-workpiece system in a straight turning process induced by random disturbances and their effect on a product surface. Basing on experimentally obtained system parameters we have done the simulations using one degree...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شیراز - دانشکده مهندسی مکانیک 1392

کابل ها محرک ربات های کابلی، به دلیل دارا بودن جرم و الاستیسیته و در نتیجه اثر وزن و شتاب حرکت آنها، به صورت خط راست کشیده نشده(اصطلاحاً شکم کرده) و بر حسب خصوصیات فیزیکی کابل، تغییر فرم میدهند. این امر، موجب پدید آمدن اختلاف در میزان کشش و طول کابل ها شده و سبب بروز خطا در مکان قرارگیری بخش متحرک، نسبت به مکان ایده آل ( در حالت عدم وجود شکم در کابل) میگردد. در این پایان نامه، به بررسی اثرات خصو...

Journal: :journal of theoretical and applied vibration and acoustics 0
mehdi eskandarzade school of mechanical engineering, college of engineering, university of tehran, 14395515 tehran, iran abolfazl masoumi school of mechanical engineering, college of engineering, university of tehran, 14395515 tehran, iran ghader faraji school of mechanical engineering, college of engineering, university of tehran, 14395515 tehran, iran

one of the great challenges in the processing of materials using equal channel angular pressing (ecap) is the high forming forces required to produce large shear deformation in the material. researchers show that the friction forces between the die and the sample constitute a great part of the total forming forces. recently, ultrasonic vibrations are successfully implemented into the ecap proce...

Journal: :فصلنامه علمی پژوهشی مهندسی مکانیک جامدات واحد خمینی شهر 0
milad shahsavari msc student, department of islamic azad university, tehran north branch, tehran, iran m. asgari - assistant professor, department of k.n.toosi university of technology, tehran, iran

in this paper deflection and free vibration of sandwich panel is studied. the core of sandwich panels is made of hexagonal honeycomb and faces are made of two different materials of carbon fiber reinforced plastic and k-aryl/epoxy covering. the governing equations are deduced from the first order sheer deformation theory (fsdt) and they are solved using generalized differential quadrature metho...

2014
K. Tao S. W. Lye J. M. Miao Xiao Hu

This paper presents a novel out-of-plane electret-based vibrational power generator (EVPG) that has both negative and positive charged electret plates integrated into a single seismic mass system. Compared with the conventional single-charged two-plate configuration, the proposed device not only exhibits an enhanced output voltage magnitude but also has a wide operational bandwidth due to sprin...

2014
Zhizheng Wu Foued Ben Amara Jitao Sun

Motivated by a class of contact vibration control problems in mechanical systems, this paper considers a regulation problem for discrete-time switched bimodal linear systems where it is desired to achieve output regulation against partially known deterministic and unknown random exogenous signals. First, a set of observer-based Youla parameterized stabilizing controllers is constructed, based o...

2002
Alexander Volya Vladimir Zelevinsky Alex Brown

The properties of the pairing interaction in the shell model framework are considered with the aid of an exact numerical solution utilizing the quasispin symmetry. We emphasize the features which are out of reach for the usual approximate techniques based on the BCS approach supplemented by the random phase approximation treatment of pair vibrations, especially in the region of weak pairing whe...

Journal: :Metals 2021

Lattice structures are lightweight engineering components suitable for a great variety of applications, including those in which the structural integrity under vibration fatigue is paramount importance. In this work, we experimentally and numerically investigate dynamic response two distinct lattice configurations, terms damage life. Specifically, Face-Centered-Cubic (FCC) Diamond lattice-based...

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