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1. Online Three-Axis Magnetometer Hard-Iron and Soft-Iron Bias and Angular Velocity Sensor Bias Estimation Using Angular Velocity Sensors for Improved Dynamic Heading Accuracy

   https://doi.org/10.55417/fr.2022033  

   Spielvogel, Andrew ; Shah, Abhimanyu ; Whitcomb, Louis ( March 2022 , Field Robotics)

   This article addresses the problem of dynamic online estimation and compensation of hard-iron and soft-iron biases of three-axis magnetometers under dynamic motion in field robotics, utilizing only biased measurements from a three-axis magnetometer and a three-axis angular rate sensor. The proposed magnetometer and angular velocity bias estimator (MAVBE) utilizes a 15-state process model encoding the nonlinear process dynamics for the magnetometer signal subject to angular velocity excursions, while simultaneously estimating nine magnetometer bias parameters and three angular rate sensor bias parameters, within an extended Kalman filter framework. Bias parameter local observability is numerically evaluated. The bias-compensated signals, together with three-axis accelerometer signals, are utilized to estimate bias-compensated magnetic geodetic heading. Performance of the proposed MAVBE method is evaluated in comparison to the widely cited magnetometer-only TWOSTEP method in numerical simulations, laboratory experiments, and full-scale field trials of an instrumented autonomous underwater vehicle in the Chesapeake Bay, Maryland, USA. For the proposed MAVBE, (i) instrument attitude is not required to estimate biases, and the results show that (ii) the biases are locally observable, (iii) the bias estimates converge rapidly to true bias parameters, (iv) only modest instrument excitation is required for bias estimate convergence, and (v) compensation for magnetometer hard-iron and soft-iron biases dramatically improves dynamic heading estimation accuracy. 

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2. Conversion of hydroperoxides to carbonyls in field and laboratory instrumentation: Observational bias in diagnosing pristine versus anthropogenically controlled atmospheric chemistry: ROOH observational bias

   https://doi.org/10.1002/2014GL061919  

   Rivera-Rios, J. C. ; Nguyen, T. B. ; Crounse, J. D. ; Jud, W. ; St. Clair, J. M. ; Mikoviny, T. ; Gilman, J. B. ; Lerner, B. M. ; Kaiser, J. B. ; de Gouw, J. ; et al ( December 2014 , Geophysical Research Letters)
3. B-periodic oscillations in the Hall-resistance induced by a dc-current-bias under combined microwave-excitation and dc-current bias in the GaAs/AlGaAs 2D system

   https://doi.org/10.1038/s41598-018-26009-z  

   Liu, Han-Chun ; Reichl, C. ; Wegscheider, W. ; Mani, R. G. ( December 2018 , Scientific Reports)
4. Warning, Bias May Occur: A Proposed Approach to Detecting Cognitive Bias in Interactive Visual Analytics

   https://doi.org/10.1109/VAST.2017.8585669  

   Wall, Emily ; Blaha, Leslie M. ; Franklin, Lyndsey ; Endert, Alex ( October 2017 , IEEE Visual Analytic Science and Technology (VAST))
5. Bias and Bias Line Effects on Wideband RF Power Amplifier Performance

   https://doi.org/10.1109/WAMICON53991.2022.9786174  

   Sear, William ; Donahue, Devon T. ; Pirrone, Michelle ; Barton, Taylor W. ( April 2022 , IEEE Wireless and Microwave Technology Conference)

   The challenges associated with efficiently and effectively linearizing a nonlinear power amplifier (PA) over wide signal bandwidths are increasingly important to the design of 5G front-ends. Conventional digital linearization techniques are limited by absolute bandwidth, while the RF-domain nonlinear PA typically exhibits consistent fractional bandwidth even as the carrier frequency is increased. Therefore, RF-domain design techniques, like those focusing on bias-line impedance selection, are critical for overall distortion reduction. To evaluate bias-line effects, a demonstrator PA is here investigated over a range of Class-AB biases and over a range of drain inductance values. The characterization under two-tone and LTE-like modulated excitations with 10-MHz and 100-MHz instantaneous bandwidth shows that the conventional linear-efficiency trade-off in bias design does not necessarily hold true for wide instantaneous bandwidths. Additionally, techniques to synthesize a negative baseband impedance using low frequency feedback are discussed. 

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