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Now showing items 21-30 of 143
Force spectroscopy using bimodal frequency modulation atomic force microscopy
(American Physical Society, 2011-02-15)
We propose a force-spectroscopy technique where a higher order mode of a cantilever is excited simultaneously with the first. Resonance tracking of both vibration modes through a frequency modulation scheme provides a way ...
Resonant harmonic response in tapping-mode atomic force microscopy
(American Physical Society, 2004)
Higher harmonics in tapping-mode atomic force microscopy offers the potential for imaging and sensing material properties at the nanoscale. The signal level at a given harmonic of the fundamental mode can be enhanced if ...
High-resolution imaging of elastic properties using harmonic cantilevers
(Elsevier, 2004)
We present a micromachined scanning probe cantilever, in which a specific higher-order flexural mode is designed to be resonant at an exact integer multiple of the fundamental resonance frequency. We have fabricated such ...
Modeling the effect of subsurface interface defects on contact stiffness for ultrasonic atomic force microscopy
(AIP Publishing LLC, 2004)
We present a model predicting the effects of mechanical defects at layer interfaces on the contact
stiffness measured by ultrasonic atomic force microscopy sAFMd. Defects at subsurface interfaces
result in changes at the ...
Enhancing higher harmonics of a tapping cantilever by excitation at a submultiple of its resonance frequency
(American Physical Society, 2005-03)
In a tapping-mode atomic force microscope, the frequency spectrum of the oscillating cantilever contains higher harmonics at integer multiples of the excitation frequency. When the cantilever oscillates at its fundamental ...
Using phase relations in microstrip directional couplers to achieve high directivity
(2013)
We analyze the microstrip directional couplers with a special focus on the phase difference between the coupled and isolated ports. The analysis uses the even-odd mode decomposition technique and network theory. The results ...
An efficient parallelization technique for high throughput FFT-ASIPs
(IEEE, 2006)
Fast Fourier Transformation (FFT) and it's inverse (IFFT) are used in Orthogonal Frequency Division Multiplexing (OFDM) systems for data (de)modulation. The transformations are the kernel tasks in an OFDM implementation, ...
Analysis of mutual acoustic coupling in CMUT arrays using an accurate lumped element nonlinear equivalent circuit model
(2012)
We use an accurate nonlinear equivalent circuit model to analyze CMUT arrays with multiple cells, where every cell in the array is coupled to other cells at their acoustic terminals through a mutual radiation impedance ...
Designing transmitting CMUT cells for airborne applications
(Institute of Electrical and Electronics Engineers Inc., 2014)
We report a new mode of airborne operation for capacitive micromachined ultrasonic transducers (CMUT), in which the plate motion spans the entire gap without collapsing and the transducer is driven by a sinusoidal voltage ...
Application of asymptotic waveform evaluation for time-domain analysis of nonlinear circuits
(Taylor & Francis, 1997)
A method is described to exploit asymptotic waveform evaluation (AWE) in the time-domain analysis of nonlinear circuits by using SPICE models for nonlinear devices such as diodes, transistors, etc. Although AWE has been ...