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Showing results for: simulation

Quasi-phase-matched second harmonic generation in silicon nitride ring resonators controlled by static electric field.

Research RF Safe Research Library Jan 1, 2013

This paper proposes and simulates actively-controlled second harmonic generation in a silicon nitride ring resonator. Quasi-phase matching is induced by a periodic static electric field generated by voltage applied to electrodes along the ring. Simulations report a calculated efficiency of -21.67 dB at 60 mW pump…

Enhanced optical absorption and electric field resonance in diabolo metal bar optical antennas.

Research RF Safe Research Library Jan 1, 2013

This engineering study investigates resonance behavior in diabolo metal bar optical antennas using FDTD numerical simulations and a dipole oscillator model. It reports that narrowing the antenna waist increases optical absorption and near-field enhancement at resonance and produces a red-shift in resonant…

Cancellation properties in Hall magnetohydrodynamics with a strong guide magnetic field.

Research RF Safe Research Library Jan 1, 2013

This paper analyzes compressible Hall magnetohydrodynamic turbulence with an external strong guide magnetic field using signed measure analysis. In simulations varying ion skin depth to modulate the Hall term, increasing the Hall term is reported to reduce the fractal dimension of current and vorticity sheets. The…

Polymer-disordered liquid crystals: susceptibility to an electric field.

Research RF Safe Research Library Jan 1, 2013

This study models nematic liquid crystals embedded in random polymer networks, where disorder disrupts long-range order and produces a glassy state. It uses simulations and an Imry-Ma-like analytic approach to visualize domains, predict domain size, and calculate the response to an applied electric field. The authors…

Simulation of colloidal fouling by coupling a dynamically updating velocity profile and electric field interactions with Force Bias Monte Carlo methods for membrane filtration.

Research RF Safe Research Library Jan 1, 2013

This engineering simulation study models colloidal particle transport and deposition in a membrane filtration channel at a particle volume fraction of 10%. The model couples a dynamically updating crossflow velocity field with particle-particle and particle-membrane interaction potentials (electrostatic double layer…

Simulations of magnetic field generation in unmagnetized plasmas via beat-wave current drive.

Research RF Safe Research Library Jan 1, 2012

This paper reports the scientific basis and 2D electromagnetic particle-in-cell simulation results for magnetizing an initially unmagnetized plasma using beat-wave current drive. Simulations across different angles between injected waves show beat-wave generation consistent with theoretical predictions and reveal…

Ground-state structures and structural transitions in a monolayer of magnetic dipolar particles in the presence of an external magnetic field.

Research RF Safe Research Library Jan 1, 2012

This physics study uses analytical calculations and Monte Carlo simulations to determine ground-state structures of monodisperse ferrofluid monolayers under external magnetic fields. It reports structural transitions depending on whether the field is perpendicular or parallel to the monolayer plane, with different…

Effects of chain stiffness and salt concentration on responses of polyelectrolyte brushes under external electric field.

Research RF Safe Research Library Jan 1, 2011

This paper reports molecular dynamics simulations of polyelectrolyte brushes subjected to external electric fields, focusing on how chain stiffness and salt concentration affect responses. The simulations suggest higher salt concentrations strengthen an induced opposing field from ion redistribution, which resists…

A handheld preconcentrator for the rapid collection of cancerous cells using dielectrophoresis generated by circular microelectrodes in stepping electric fields.

Research RF Safe Research Library Jan 1, 2011

This engineering study describes a handheld microfluidic preconcentrator that uses dielectrophoresis generated by circular microelectrodes with a stepping electric field. Numerical simulations were used to illustrate the electric-field concept. In experiments, HeLa cells were reportedly preconcentrated within 160…

Dynamic control of adsorption sensitivity for photo-EMF-based ammonia gas sensors using a wireless network.

Research RF Safe Research Library Jan 1, 2011

This engineering paper proposes a control method for a photo-electromagnetic field (EMF)-based ammonia gas sensor that uses a wireless network and adjusts illumination light intensity. It reports that measurement error is minimized over 3800 ppm ammonia when the concentration corresponds to an optimal illumination…

Historical building monitoring using an energy-efficient scalable wireless sensor network architecture.

Research RF Safe Research Library Jan 1, 2011

This engineering paper describes low-power wireless sensor nodes and a cluster-based dynamic-tree hierarchical WSN architecture for monitoring historical buildings and wooden artifacts for early pest detection. The authors report simulation and demonstration results indicating improved scalability and reliability…

Electric field analysis of breast tumor cells.

Research RF Safe Research Library Jan 1, 2011

This paper reports a MAXWELL 3D simulation study of electric field distribution in a tissue/tumor model relevant to electrical-pulse-mediated drug delivery. The authors report lower electric field strength in tumor tissue compared with normal cells. They interpret this as potentially increasing tumor susceptibility…

Correction of main and transmit magnetic field (B0 and B1) inhomogeneity effects in multicomponent-driven equilibrium single-pulse observation of T1 and T2.

Research RF Safe Research Library Jan 1, 2011

This methods paper addresses how B0 (main field) and B1 (transmit field) inhomogeneities can bias SPGR and bSSFP steady-state MRI signals used for multicomponent T1/T2 relaxometry and myelin water analysis. It describes using DESPOT1-HIFI to calibrate flip angles and adding a B0-related parameter with multiple…

Spatial and Temporal Variations of a Screening Current Induced Magnetic Field in a Double-Pancake HTS Insert of an LTS/HTS NMR Magnet.

Research RF Safe Research Library Jan 1, 2009

This engineering study measures and simulates screening current induced magnetic fields (SCF) in a Bi2223-tape HTS insert used in an LTS/HTS NMR magnet at 77 K. SCF was induced by the insert self-field, an external 5-T background magnet, and their combination, and axial field distributions and temporal variations…

Plasmonic array nanoantennas on layered substrates: modeling and radiation characteristics.

Research RF Safe Research Library Jan 1, 2009

This theoretical/engineering study models arrays of plasmonic core-shell nano-radiators positioned over layered substrates using a Green's function dipole approach. The model is validated with full-wave FDTD simulations. The authors report that nanoparticle arraying and multilayer substrate design can be used to…

Microscopic dynamics of the orientation of a hydrated nanoparticle in an electric field.

Research RF Safe Research Library Jan 1, 2009

This paper uses atomistic simulations to examine how a nonpolar nanoparticle suspended in water reorients under an applied electric field. The authors report that molecular-level effects increase the torque relative to continuum estimates and substantially speed up reorientation above a stated field threshold. The…

Influence of mashed potato dielectric properties and circulating water electric conductivity on radio frequency heating at 27 MHz.

Research RF Safe Research Library Jan 1, 2008

This engineering study used experiments, computer simulations, and simplified analytical calculations to examine how mashed potato dielectric properties and circulating water electrical conductivity affect RF heating at 27 MHz. The authors report that higher circulating water conductivity and higher salt content in…

Plasma-assembled carbon nanotubes: electric field-related effects.

Research RF Safe Research Library Jan 1, 2008

This engineering-focused paper compares carbon nanotube growth in dense low-temperature plasma versus on a substrate surface using hybrid/Monte-Carlo simulations. It reports that plasma parameters strongly influence ion fluxes and nanotube growth kinetics, with large differences in growth rates and fluxes between…

Minimal-SAR RF pulse optimization for parallel transmission in MRI.

Research RF Safe Research Library Jan 1, 2008

This engineering study presents an optimization framework to design RF pulses for parallel transmission MRI with the goal of minimizing SAR. Using computer simulations of a 4-channel system, the authors report significant SAR reduction while maintaining excitation pattern quality and without increasing pulse…

Coil design considerations for deep-brain transcranial magnetic stimulation (dTMS).

Research RF Safe Research Library Jan 1, 2008

This engineering-focused conference paper proposes figures of merit to evaluate deep-brain transcranial magnetic stimulation (dTMS) coil designs, focusing on depth penetration, scalp stimulation, focality, and energy. It analyzes circular crown and C-core coils and reports reduced electric-field attenuation with…

Magnetic field distribution and signal decay in functional mri in very high fields (up to 9.4 T) using monte carlo diffusion modeling.

Research RF Safe Research Library Jan 1, 2007

This paper models extravascular MRI signal decay (R2/R2*) as a function of blood oxygenation, vessel geometry, and magnetic field strength up to 9.4 T using Monte Carlo diffusion simulations. It reports different vessel-size dependencies for Hahn-spin-echo versus gradient-recalled-echo relaxation across field…

Chaotic mixing induced by a magnetic chain in a rotating magnetic field.

Research RF Safe Research Library Jan 1, 2007

This paper studies chaotic mixing driven by breakup and reformation of a magnetic particle chain under a rotating magnetic field using direct numerical simulation. The authors report that chain motion and the degree of chaos depend strongly on the Mason number, and that a limited Mason number range produces repeated…

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