Nonlinear Control Systems Simulation Using Spreadsheets

In this paper, a method for simulating nonlinear control systems using spreadsheets is presented. Various nonlinear blocks are simulated using graphics and cell formulas, and are generated by clicking on specially developed toolbar buttons. These blocks can be connected to one another using a simple and intuitive procedure again based on graphics and toolbar buttons. A complete nonlinear system can thus be created by generating and connecting its constituting basic blocks, using the simple graphics interface provided. The corresponding data may then be entered in the familiar manner as illustrated, and finally the system can be simulated literally at the click of a button. Such a system can be analyzed by calculating its time response to any input signal or by using other methods such as phase-plane trajectories. The simulation is characterized by its availability, flexibility, and simplicity. The paper provides several examples to illustrate the simulation capabilities available. The first example considers a servo with a dead-zone and a saturation amplifier, the second illustrates the steps required to obtain a phase-plane trajectory, and the third example considers a nonlinear system having a PI controller and nonlinearity consisting of soft saturation. The final example illustrates a relay-controlled servo system

Simple Design Procedure for 2D SWAs with Specified Sidelobe Levels and Inclined Coupling Slots

A simple procedure for the design of two-dimensional SWA array systems with desired sidelobe level ratio (SLR) is presented. The described procedure finds the slots length, width, locations and displacements from the centerline, for each branch waveguide. For a specified number of branch waveguides, the method also finds the rotation angle of each of the coupling slots. To explain the controllable SLR, two 2D SWA array systems designed for an SLR higher than 20 dB are illustrated and compared

COMPLEX-COEFFICIENT POLYNOMIAL ROOTS BY A STABILITY CRITERION

Abstract. Computation of polynomial roots is a problem that arises in various domains of science and engineering, and has thus received much attention in years, with marked recent progress. This paper introduces a new numerical algorithm for computing the roots of a complex-coefficient polynomial of degree n. The method is based on bracketing, in the spirit of Lehmer-Schur [1], but uses a robust stability criterion from system theory due to Agashe [2], which generalizes the Routh-Hurwitz criterion. The algorithm is simple to implement, and its accuracy is tested using both well- and ill-conditioned polynomials. The results show excellent convergence, as compared to the companion-matrix eigenvalues method used often in numerical packages, such as MATLAB [3]. The algorithm is also flexible: precision can be tuned, and custom search regions can be specified. Key Words. Polynomial, root, algorithm, bracketing and stability. 1

Wearable Blood Pressure Sensing Based on Transmission Coefficient Scattering for Microstrip Patch Antennas

Painless, cuffless and continuous blood pressure monitoring sensors provide a more dynamic measure of blood pressure for critical diagnosis or continuous monitoring of hypertensive patients compared to current cuff-based options. To this end, a novel flexible, wearable and miniaturized microstrip patch antenna topology is proposed to measure dynamic blood pressure (BP). The methodology was implemented on a simulated five-layer human tissue arm model created and designed in High-Frequency Simulation Software “HFSS”. The electrical properties of the five-layer human tissue were set at the frequency range (2–3) GHz to comply with clinical/engineering standards. The fabricated patch incorporated on a 0.4 mm epoxy substrate achieved consistency between the simulated and measured reflection coefficient results at flat and bent conditions over the frequency range of 2.3–2.6 GHz. Simulations for a 10 g average specific absorption rate (SAR) based on IEEE-Standard for a human arm at different input powers were also carried out. The safest input power was 50 mW with an acceptable SAR value of 3.89 W/Kg < 4W/Kg. This study also explored a novel method to obtain the pulse transit time (PTT) as an option to measure BP. Pulse transmit time is based on obtaining the time difference between the transmission coefficient scattering waveforms measured between the two pairs of metallic sensors underlying the assumption that brachial arterial geometries are dynamic. Consequently, the proposed model is validated by comparing it to the standard nonlinear Moens and Korteweg model over different artery thickness-radius ratios, showing excellent correlation between 0.76 ± 0.03 and 0.81 ± 0.03 with the systolic and diastolic BP results. The absolute risk of arterial blood pressure increased with the increase in brachial artery thickness-radius ratio. The results of both methods successfully demonstrate how the radius estimates, PTT and pulse wave velocity (PWV), along with electromagnetic (EM) antenna transmission propagation characteristics, can be used to estimate continuous BP non-invasively