Recent Advances in Learning and Control

Blondel, Vincent D.; Boyd, Stephen; Kimura, Hidenori

doi:10.1007/978-1-84800-155-8

Cited by 74 publications

(1 citation statement)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(to be minimized instead of maximized), then (23) becomes a standard convex optimization problem. To solve (24), we can use CVX, a package for specifying and solving convex programs [44,45]. For example, the CVX solution to (24) for c = 0.1 and K = 1 is…”

Section: D-optimal Designmentioning

confidence: 99%

On the calculation of theD-optimal multisine excitation power spectrum for broadband impedance spectroscopy measurements

Sanchez

Rojas

Vandersteen

et al. 2012

Meas. Sci. Technol.

View full text Add to dashboard Cite

The successful application of impedance spectroscopy in daily practice requires accurate measurements for modeling complex physiological or electrochemical phenomena in a single frequency or several frequencies at different (or simultaneous) time instants. Nowadays, two approaches are possible for frequency domain impedance spectroscopy measurements: (1) using the classical technique of frequency sweep and (2) using (non-)periodic broadband signals, i.e. multisine excitations. Both techniques share the common problem of how to design the experimental conditions, e.g. the excitation power spectrum, in order to achieve accuracy of maximum impedance model parameters from the impedance data modeling process. The original contribution of this paper is the calculation and design of the D-optimal multisine excitation power spectrum for measuring impedance systems modeled as 2R-1C equivalent electrical circuits. The extension of the results presented for more complex impedance models is also discussed. The influence of the multisine power spectrum on the accuracy of the impedance model parameters is analyzed based on the Fisher information matrix. Furthermore, the optimal measuring frequency range is given based on the properties of the covariance matrix. Finally, simulations and experimental results are provided to validate the theoretical aspects presented.

show abstract

Section: D-optimal Designmentioning

confidence: 99%

On the calculation of theD-optimal multisine excitation power spectrum for broadband impedance spectroscopy measurements

Sanchez

Rojas

Vandersteen

et al. 2012

Meas. Sci. Technol.

View full text Add to dashboard Cite

show abstract

Convex gradient optimization for increased spatiotemporal resolution and improved accuracy in phase contrast MRI

Middione

Ennis

2013

Magnetic Resonance in Med

View full text Add to dashboard Cite

Purpose To evaluate convex gradient optimization (CVX) for increased spatiotemporal resolution and improved accuracy for phase‐contrast MRI (PC‐MRI). Methods A conventional flow‐compensated and flow‐encoded (FCFE) PC‐MRI sequence was compared with a CVX PC‐MRI sequence using numerical simulations, flow phantom experiments, and in vivo experiments. Flow measurements within the ascending aorta, main pulmonary artery, and right/left pulmonary arteries of normal volunteers (N = 10) were acquired at 3T and analyzed using a conventional FCFE sequence and a CVX sequence with either higher spatial resolution or higher temporal resolution. All sequences mitigated chemical shift–induced phase errors and used equivalent breath‐hold durations. Results Chemical shift–optimized PC‐MRI has increased sequence efficiency when using CVX, which can provide either higher spatial or higher temporal resolution compared with conventional FCFE PC‐MRI. Numerical simulations, flow phantom experiments, and in vivo experiments indicate that CVX measurements of total flow and peak velocity are increased and more accurate when compared with FCFE. Conclusion CVX PC‐MRI increases sequence efficiency while reducing chemical shift–induced phase errors. This can be used to provide either higher spatial or higher temporal resolution than conventional chemical shift–mitigated PC‐MRI methods to provide more accurate measurements of blood flow and peak velocity. Magn Reson Med 72:1552–1564, 2014. © 2013 Wiley Periodicals, Inc.

show abstract