Browsing by Subject "Velocity"

Now showing 1 - 10 of 10

Open Access
Finite size effects in cooperative molecular motors
(Elsevier B.V., 2003) Taneri, S.; Yalabik, M. C.
We have studied the ballistic and damped dynamics of finite size cooperative molecular motors. We study the effect of finite size on average quantities such as sliding velocity, as well as the statistics of fluctuations in these quantities. We observed stalling for the over damped case.
Open Access
Incorporating doppler velocity measurement for track initiation and maintenance
(IET, 2006) Kural, F.; Arıkan, F.; Arıkan, Orhan; Efe, M.
Performance of multiple target tracking algorithms in complex environments heavily relies on the success of track initiation and measurement-to-track association algorithms. Doppler velocity measurement is the major discriminant of clutter from the target of interest with relatively higher velocities. This work summarizes the analytical derivations and presents simulation results about track initiation and maintenance using Doppler velocity reports along with the 3D position measurements extracted by a phased array radar.
Open Access
Interpolation techniques to improve the accuracy of the plane wave excitations in the finite difference time domain method
(Wiley-Blackwell Publishing, Inc., 1997-11) Oğuz, U.; Gürel, Levent
The importance of matching the phase velocity of the incident plane wave to the numerical phase velocity imposed by the numerical dispersion of the three-dimensional (3-D) finite difference time domain (FDTD) grid is demonstrated. In separate-field formulation of the FDTD method, a plane wave may be introduced to the 3-D computational domain either by evaluating closed-form incident-field expressions or by interpolating from a 1-D incident-field array (IFA), which is a 1-D FDTD grid simulating the propagation of the plane wave. The relative accuracies and efficiencies of these two excitation schemes are compared, and it has been shown that higher-order interpolation techniques can be used to improve the accuracy of the IFA scheme, which is already quite efficient.
Open Access
Magnetic and electric Aharonov-Bohm effects in nanostructures
(Elsevier BV, 1996) Kulik, I. O.
The paper reviews and extends the magnetic Aharonov-Bohm effect (persistent current, resistance oscillation) in normal-metal rings including spin-independent and spin-dependent hopping, Zeeman splitting, magnetic textures and wheels, ring rotation and weak coupling, as well as the electric Aharonov-Bohm effect ("persistent charge") in small metallic contacts. We then discuss dynamical screening effects in a surface charge in a metal. Energy dissipation due to motion of the surface charge has a singularity at the velocity of motion equal to the phonon propagation velocity. Surface image of an external charge inside the metal is strongly distorted at the velocity of motion larger than the Fermi velocity.
Open Access
A novel equivalent circuit model for CMUTs
(IEEE, 2009-09) Oğuz, H. Kağan; Olcum, Selim; Senlik, Muhammed N.; Atalar, Abdullah; Köymen, Hayrettin
A nonlinear equivalent circuit for immersed transmitting capacitive micromachined ultrasonic transducers (CMUTs) is presented. The velocity profile across the CMUT surface maintains the same form over a wide frequency range. This property and the profile are used to model both the electromechanical conversion and the mechanical section. The model parameters are calculated considering the root mean square of the velocity distribution on the membrane surface as the through variable. The new model is compared with the FEM simulation results. The new model predicts the CMUT performance very accurately. ©2009 IEEE.
Open Access
On the stabilization of a cable with a tip mass
(IEEE, 1994) Morgül, Ö.; Rao, B. P.; Conrad, F.
In this note, we consider a vertical cable which is pinched at the upper end. A mass is attached at the lower end where a control force is also applied. We show that this hybrid system is uniformly stabilized by choosing a suitable control law for the control force depending on the velocity and angular velocity at the free end. Moreover for specific values of the feedback coefficients, we obtain the rate of decay of the energy of the system.
Open Access
Performance evaluation of track association and maintenance for a MFPAR with doppler velocity measurements
(2010) Kural, F.; Arikan, F.; Arıkan, Orhan; Efe, M.
This study investigates the effects of incorporating Doppler velocity measurements directly into track association and maintenance parts for single and multiple target tracking unit in a multi function phased array radar (MFPAR). Since Doppler velocity is the major discriminant of clutter from a desired target, the measurement set has been expanded from range, azimuth and elevation angles to include Doppler velocity measurements. We have developed data association and maintenance part of a well known tracking method, Interacting Multiple Model Probabilistic Data Association.
Open Access
Radiation properties of sources inside photonic crystals
(2003) Bulu, I.; Caglayan, H.; Özbay, Ekmel
In this work, we have experimentally studied the emission of radiation from a monopole source embedded in a photonic crystal. We have demonstrated the enhancement of radiation at the band edges and at the cavity modes including coupled cavity modes. Moreover, we have shown that the emission of radiation from a source depends on the group velocities of the modes and on the electric field intensities of the modes at the source location.
Open Access
Rapid classification of surface reflectance from image velocities
(Springer, Berlin, Heidelberg, 2009) Doerschner, Katja; Kersten, D.; Schrater P.
We propose a method for rapidly classifying surface reflectance directly from the output of spatio-temporal filters applied to an image sequence of rotating objects. Using image data from only a single frame, we compute histograms of image velocities and classify these as being generated by a specular or a diffusely reflecting object. Exploiting characteristics of material-specific image velocities we show that our classification approach can predict the reflectance of novel 3D objects, as well as human perception. © 2009 Springer Berlin Heidelberg.
Open Access
Temperature dependence of the energy of a vortex in a two-dimensional Bose gas
(Elsevier, 2004) Rajagopal, K. K.; Tanatar, Bilal; Vignolo, P.; Tosi, M. P.
We evaluate the thermodynamic critical angular velocity Ωc(T) for creation of a vortex of lowest quantized angular momentum in a strictly two-dimensional Bose gas at temperature T, using a mean-field two-fluid model for the condensate and the thermal cloud. Our results show that (i) a Thomas-Fermi description of the condensate badly fails in predicting the particle density profiles and the energy of the vortex as functions of T; and (ii) an extrapolation of a simple Thomas-Fermi formula for Ωc(0) is nevertheless approximately useful up to T≃0.5Tc.