@article{gutierrez_gard_steer_2000, title={Nonlinear cain compression in microwave amplifiers using generalized power-series analysis and transformation of input statistics}, volume={48}, ISSN={["1557-9670"]}, DOI={10.1109/22.873911}, abstractNote={Two methods are presented for the estimation of gain compression generated by a digitally modulated carrier passed through a nonlinear RF circuit. The first one is based on developing an analytical expression for gain compression based on the transformation of input signal statistics. The second one is based on approximated expressions derived from generalized power-series analysis. The techniques are evaluated by comparing measured and predicted gain compression in a CDMA system.}, number={10}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Gutierrez, H and Gard, K and Steer, MB}, year={2000}, month={Oct}, pages={1774–1777} }
 @article{steer_harvey_mink_abdulla_christoffersen_gutierrez_heron_hicks_khalil_mughal_et al._1999, title={Global modeling of spatially distributed microwave and millimeter-wave systems}, volume={47}, ISSN={["1557-9670"]}, DOI={10.1109/22.769316}, abstractNote={Microwave and millimeter-wave systems have generally been developed from a circuit perspective with the effect of the electromagnetic (EM) environment modeled using lumped elements or N-port scattering parameters. The recent development of the local reference node concept coupled with steady-state and transient analyses using state variables allows the incorporation of unrestrained EM modeling of microwave structures in a circuit simulator. A strategy implementing global modeling of electrically large microwave systems using the circuit abstraction is presented. This is applied to the modeling of a quasi-optical power-combining amplifier.}, number={6}, journal={IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES}, author={Steer, MB and Harvey, JF and Mink, JW and Abdulla, MN and Christoffersen, CE and Gutierrez, HM and Heron, PL and Hicks, CW and Khalil, AI and Mughal, UA and et al.}, year={1999}, month={Jun}, pages={830–839} }
 @article{gutierrez_po_1998, title={Sliding-mode control of a nonlinear-input system: Application to a magnetically levitated fast-tool servo}, volume={45}, ISSN={["0278-0046"]}, DOI={10.1109/41.735336}, abstractNote={Magnetic servo levitation (MSL) is currently being investigated as an alternative to drive fast-tool servo systems that could overcome the range limitations inherent to piezoelectric driven devices while operating over a wide bandwidth. To control such systems, a feedback-linearized controller coupled with a Kalman filter has been previously described. Performance limitations that degrade tracking accuracy suggest the use of a more robust controller design approach, such as sliding-mode control. Current literature on sliding mode deals almost exclusively with systems that are affine on the input, while the magnetic fast-tool servo is nonlinear on it when the control action is current command. This paper discusses a sliding mode-based controller that overcomes the aforementioned problem by defining a modified sliding condition to calculate control action. Experimental results demonstrate the feasibility of achieving long-range fast tracking with magnetically levitated devices by using sliding-mode control.}, number={6}, journal={IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS}, author={Gutierrez, HM and Po, PI}, year={1998}, month={Dec}, pages={921–927} }
 @article{gutierrez_rust_seyam_1995, title={MODELING AND SIMULATION FOR CONTROL IN CARDING}, volume={65}, ISSN={["0040-5175"]}, DOI={10.1177/004051759506501103}, abstractNote={ The purpose of this work is to further study the transfer function model for carding introduced in a previous paper. Our goal is to develop mathematical and computational tools that will ultimately lead to the design of real-time controllers for carding. In this paper, we discuss a linear, time-variant version of the model presented for one carding group. We also present a reduced order, linear model and use it to build a linear estimator (observer) as part of a full-state feedback controller design. Computer sim ulations and experimental results are shown. }, number={11}, journal={TEXTILE RESEARCH JOURNAL}, author={GUTIERREZ, HM and RUST, JP and SEYAM, AF}, year={1995}, month={Nov}, pages={638–643} }
 @article{gutierrez_rust_1995, title={SYSTEM-IDENTIFICATION FOR A PHOTODIODE-BASED MONITORING-SYSTEM}, volume={34}, ISSN={["0019-0578"]}, DOI={10.1016/0019-0578(95)00006-l}, abstractNote={A laser-based system to monitor fiber load level in carding has been developed based on silicon PIN-photodiodes. It is desirable to establish more accurately the dynamic characteristics of the sensing system and in particular the interaction between the sensors, the sensing circuitry and the data acquisition equipment. An experimental set up that allows to evaluate the dynamics of the entire monitoring system is here presented, along with experimental results. This set up allows to determine an experimental transfer function and frequency response curves for the sensing system. In addition to this, results from the system identification procedure can be extended to develop a linearized transfer function of the sensor. Additional input-output tests can then be used to determine the parameters of such linear model from an analysis of the impulse response; a linear model of the sensor can then be used on the feedback path of a controller design based on these sensors. This technique can be extended to other processes on which controller design is under consideration and dynamic characteristics of the corresponding sensors are unknown.}, number={1}, journal={ISA TRANSACTIONS}, author={GUTIERREZ, HM and RUST, JP}, year={1995}, month={Mar}, pages={93–99} }
 @article{rust_gutierrez_1994, title={MATHEMATICAL-MODELING AND SIMULATION FOR CARDING}, volume={64}, ISSN={["0040-5175"]}, DOI={10.1177/004051759406401004}, abstractNote={ The purpose of this work is to increase the understanding of carding system dynamics based on mathematical tools that will ultimately lead to the development of on-line real-time controllers for carding. The work comprises both modeling the process and comparing simulated results with experimental data. A mathematical model for one worker-stripper group is described and subsequently expanded to model a carding engine with six carding (worker-stripper) groups. The process variable in this work is restricted to fiber areal density on the main cylinder; the expanded model predicts output (web) fiber areal density in time. Both simulated and experimental results are presented. }, number={10}, journal={TEXTILE RESEARCH JOURNAL}, author={RUST, JP and GUTIERREZ, HM}, year={1994}, month={Oct}, pages={573–578} }