Semiconductor manufacturing companies aim to achieve shortest test times for products while maintaining the product quality. Achieving shortest test times for devices requires multiple updates to the test flow and test content. Test cost varies in direct proportion to production test time required to test chips and detect fails. This thesis presents a method to achieve shortest test times by determining when the updates are needed and what are the changes to the test flow and test content. This thesis introduces a new Adaptive Test Scheme (ATS). ATS estimates individual test fail rates dynamically, per die, and makes real-time modifications to test order and test contents. ATS computes data-driven test fail rate estimates and uses the estimates to identify the required changes and trigger updates to test flow and test content. ATS uses Bayesian statistics to model the per test fail rates and update the test orders. ATS achieves test time reductions by employing per wafer elimination. ATS also incorporates a simple quality monitor, by resetting the test content at the start of next wafer. This thesis evaluates the performance of ATS with synthetic data generated by a Monte Carlo method and with production wafer sort data for two manufactured products. The product data results show ATS reduced by 20% the total test-time for one product and by 40% for a second product, with changes in product quality level below industry targets.

In this work, a computationally efficient solution for constraint management of square multi-input multi-output (MIMO) systems is presented. The solution, referred to as the Decoupled Reference Governor (DRG), maintains the highly-attractive computational features of scalar reference governors (SRG) compared to Vector Reference Governor (VRG) and Command Governor (CG). This work focuses on square MIMO systems that already achieve the desired tracking performance. The goal of DRG is to enforce output constraints and simultaneously ensure that the degradation to tracking performance is minimal. DRG is based on decoupling the input-output dynamics of the system so that every channel of the system can be viewed as an independent input-output relationship, followed by the deployment of a bank of scalar reference governors for each decoupled channel. We present a detailed set-theoretic analysis of DRG, which highlights its main characteristics. A quantitative comparison between DRG, SRG, and the VRG is also presented in order to illustrate the computational advantages of DRG. Finally, a distillation process is introduced as an example to illustrate the applicability of DRG.

In automakers' never-ending quest to reduce emissions and improve performance, the turbocharger represents a major step in advancing these goals. By repurposing waste exhaust and compressing the air intake, they are able to increase overall power. One critical control loop in the turbocharger is control of boost pressure via the wastegate. This is a highly nonlinear process and experimental data has shown that a gain-scheduled PID (proportional integral derivative) controller developed with IMC (internal model control) tuning methodology is an effective means to control boost pressure. Motivated by this successful implementation of IMC-PID tuning in the automotive world, this work hopes to extend and analyze that framework. Traditionally, the success of an IMC controller depends on the accuracy of the plant model. This research challenges this view and investigates using IMC with a gain-integrator-delay (GID) model identified at a critical frequency, regardless of the actual plant. The GID model is useful because of its simplicity to characterize and its ability to be translated to the ubiquitous PID controller easily. Three design techniques are developed: (1) design for post-hoc tuning, (2) design for closed loop bandwidth, and (3) design for phase margin. In addition, these techniques are investigated via a Monte Carlo simulation to determine efficacy for when there exists plant/model mismatch. Finally, the three techniques are applied to control the speed of an inertia disk on the Quanser Servo 2 device.

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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990. / Includes bibliographical references (leaves 115-116). / by Stephen MacDonald Foster. / Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1990.

This thesis work builds upon the theoretical studies and full-wave analysis of radio frequency micro- and nano-electromechanical systems (RF M/NEMS) integrated multi-functional reconfigurable antennas(MRAs). This is a part of the overall M/NEMS research efforts performed in the RF NEMS Laboratory at USU, which includes design, microfabrication, test, and characterization of M/NEMS integrated congitive wireless communication systems (fig. A.1). The thesis work focuses on two MRAs. 1) A triple bands patch antenna which can operate at 800, 2400, and 4900 MHz in response to public safety wireless communication systems. 2) A multi-frequency multi-polarization MRA for wireless personal area networking application (WPAN) operating at 57-64 GHz frequency range

<p>Major problems of the Foot Drop treatment are expensive and complex solutions. This work</p><p>presents the performance of a new inexpensive method named as Semi-Active Ankle Foot</p><p>Orthosis (SAAFO). The concept of this approach is to use inexpensive sensors to detect foot step</p><p>movement. The signals from the sensors afterwards will be fed to a control system of SAAFO in</p><p>runtime for a smooth foot movement of a drop foot patient while walking. Different sensors have</p><p>been studied in detail along with comparison to the proposed sensor system and mechanical</p><p>design. The signals from the sensors are used to detect different phases of human walking. These</p><p>sensors are placed at different positions on an orthosis and their signals are studied in detail.</p><p>Experiments have been done in different conditions to get a realistic picture either this assembly</p><p>can be implemented commercially. Signals are plotted and discussed yielding that the human</p><p>walking phases can be easily and accurately detected using inexpensive sensor assembly.</p>

Ultrasound waves have been used for imaging purposes for many years. However, a liquid interface has always been necessary between the transducer and the object being imaged due to a high mechanical resistance at the air-transducer interface. Recent advances in transducers have made it possible to omit the liquid interface, allowing imaging to be done through air interfaces. Because this is a relatively new field, research into ultrasound propagation in air is very limited. A comprehensive model of how an ultrasound wave propagates through air would expedite the study of air-coupled ultrasound for imaging. This thesis presents a mathematical model of two-dimensional linear acoustic wave propagation in air. The model takes as input the frequency and amplitude of an acoustic signal and outputs the pressure field over varying longitudinal and lateral distances from the source. The benefits of a mathematical model over a finite element model are first discussed, then the mathematical model for acoustic propagation in air is developed using both computer simulations and physical experiments in an anechoic chamber. Results are presented and compared to experimental data to confirm the validity of the mathematical model.

The modification of single crystal epitaxial ZnO thin films grown by Pulsed Laser Deposition on c-axis oriented sapphire substrates by Ion Beam Processing was investigated. Nitrogen doping of the films was attempted using nuclear transmutation using the ¹⁶O (³He, ⁴He) ¹⁵O reaction at 6.6 MeV. The ¹⁵O product is unstable and decays to ¹⁵N after several minutes by positron emission. There are several potential advantages to using nuclear transmutation including producing nitrogen atoms on the correct lattice site for doping and reduced crystal damage as compared to conventional ion beam implantation. In the experiments in this thesis the doping levels achieved ~10¹⁴ cm^-3 were too low to be expected to dope the films to p-type. However several beneficial effects due to the ion beam processing were observed, including large increases in resistivity, reduction of defect luminescence, and substantial increases in the response of photoconductive detectors. In addition to desired effects in some films it was also found that in some films bubble like structures approximately 10 ìm in diameter were formed where the thin film delaminated from the surface. It was assumed that mechanism for the bubble formation was the build up of helium gas at the sapphire/ZnO interface.