In this dissertation we propose several DFT techniques specific to 3D stacked IC systems. The goal has explicitly been to create techniques that integrate easily with existing IC test systems. Specifically, this means utilizing scan- and wrapper-based techniques, two foundations of the digital IC test industry. First, we describe a general test architecture for 3D ICs. In this architecture, each tier of a 3D design is wrapped in test control logic that both manages tier test pre-bond and integrates the tier into the large test architecture post-bond. We describe a new kind of boundary scan to provide the necessary test control and observation of the partial circuits, and we propose a new design methodology for test hardcore that ensures both pre-bond functionality and post-bond optimality. We present the application of these techniques to the 3D-MAPS test vehicle, which has proven their effectiveness. Second, we extend these DFT techniques to circuit-partitioned designs. We find that boundary scan design is generally sufficient, but that some 3D designs require special DFT treatment. Most importantly, we demonstrate that the functional partitioning inherent in 3D design can potentially decrease the total test cost of verifying a circuit. Third, we present a new CAD algorithm for designing 3D test wrappers. This algorithm co-designs the pre-bond and post-bond wrappers to simultaneously minimize test time and routing cost. On average, our algorithm utilizes over 90% of the wires in both the pre-bond and post-bond wrappers. Finally, we look at the 3D vias themselves to develop a low-cost, high-volume pre-bond test methodology appropriate for production-level test. We describe the shorting probes methodology, wherein large test probes are used to contact multiple small 3D vias. This technique is an all-digital test method that integrates seamlessly into existing test flows. Our experimental results demonstrate two key facts: neither the large capacitance of the probe tips nor the process variation in the 3D vias and the probe tips significantly hinders the testability of the circuits. Taken together, this body of work defines a complete test methodology for testing 3D ICs pre-bond, eliminating one of the key hurdles to the commercialization of 3D technology.

<p>  </p> <p>In the first chapter, we developed a dynamic equilibrium model of multiple stocks with extrapolators under the framework of Barberis, Greenwood, Jin, and Shleifer (2015a). Our model builds on the fact that extrapolative investors assign different relative weights of recent versus distant past return when forming their beliefs. We find that stock price increases in its own past performance measure, and is additionally associated with the past performance measure of the other stock if their dividends are correlated. The stock with higher relative weight have higher stock price, higher stock volatility, and lower risk premium. Both the own stock’s and the other stock’s past performance measure negatively predicts future stock price changes. </p> <p><br></p> <p>The second chapter includes Adem Atmaz, Stefano Cassella, and Huseyin Gulen as co-authors. In this chapter, we document considerable cross-sectional variation in survey expectations about aggregate stock market returns. While most investors are extrapolators who expect higher returns after a good market performance, some are contrarians who expect lower returns after a good performance. More notably, compared to extrapolators, contrarians have less persistent expectations that are corrected more quickly. Accordingly, we develop a dynamic equilibrium model accounting for these differences in expectations and find that the equilibrium stock price exhibits short-term momentum and long-term reversal as in the data. Furthermore, we test the key predictions of the model linking the shortterm momentum to observable differences between extrapolators and contrarians and find supportive evidence for our mechanism. </p> <p><br></p> <p>The third chapter includes Adem Atmaz and Suleyman Basak as co-authors. In this chapter, we develop a dynamic model of costly stock short-selling and lending market and obtain implications simultaneously supporting many empirical regularities. In our model, investors’ belief disagreement leads to lenders and short-sellers, who pay shorting fees to borrow stocks from lenders. Our main novel results are as follows. Short interest predicts future stock returns negatively and has a stronger predictive power than the corresponding dividend-price ratio. Higher short-selling risk can be associated with lower stock returns and less short-selling activity. Stock volatility is increased under costly short-selling. An application to the GameStop episode yields implications consistent with observed patterns. </p>

With the advances in wireless communication systems, antennas with different shapes and design have achieved great demand and are desirable for many uses such as personal communication systems, and other applications involving wireless communication. This has resulted in different shapes and types of antenna design in order to achieve different antenna characteristic. One attractive approach to the design of antennas is to suppress or attenuate harmonic contents due to the non-linear operation of the Radio Frequency (RF) front end. The objectives of this work were to investigate, design and implement antennas for harmonic suppression with the aid of a genetic algorithm (GA). Several microstrip patch antennas were designed to operate at frequencies 1.0, 1.8 and 2.4 GHz respectively. The microstrip patch antenna with stub tuned microstrip lines was also employed at 1.0 and 1.8 GHz to meet the design objectives. A new sensing patch technique is introduced and applied in order to find the accepted power at harmonic frequencies. The evaluation of the measured power accepted at the antenna feed port was done using an electromagnetic (EM) simulator, Ansoft Designer, in terms of current distribution. A two sensors method is presented on one antenna prototype to estimate the accepted power at three frequencies. The computational method is based on an integral equation solver using adaptive surface meshing driven by a genetic algorithm. Several examples are demonstrated, including design of coaxially-fed, air-dielectric patch antennas implanted with shorting and folded walls. The characteristics of the antennas in terms of the impedance responses and far field radiation patterns are discussed. The results in terms of the radiation performance are addressed, and compared to measurements. The presented results of these antennas show a good impedance matching at the fundamental frequency with good suppression achieved at the second and third harmonic frequencies. / Home government

This work deals with the most famous constructions of planar antennas. The work analyses selected methods of connecting planar antennas' charging with the possibility of impedance adaptation. An important part of the work consists of description of techniques for increasing bandwidth and conversely techniques for reducing the dimensions which are important for the design of planar antennas for mobile devices. The antennas were designed by means of theoretical basis and their properties were examined in the electromagnetic field simulator. The selected antenna model was constructed and its parameters were measured experimentally. The matching circuit for the antenna to tune it to different resonant frequencies was designed and constructed.

Three testing methods are proposed to characterize properties of fuel cell materials that affect the mechanical durability of proton exchange membranes (PEMs). The first two methods involved measuring the in-plane biaxial strength of PEMs and the biaxial hygrothermal stresses that occur in PEMs during hygrothermal cycles. The third method investigated the nonuniform thickness and compressibility of gas diffusion media which can lead to concentrated compressive stresses in the PEM in the through-plane direction. Fatigue and creep to leak tests using multi-cell pressure-loaded blister fixtures were conducted to obtain the lifetimes of PEMs before reaching a threshold value of gas leakage. These tests are believed to be more relevant than quasi-static uniaxial tensile to rupture tests because of the introduction of biaxial cyclic and sustained loading and the use of gas leakage as the failure criterion. They also have advantages over relative humidity cycling test because of the controllable mechanical loading. Nafion® NRE-211 membrane was tested at three different temperatures and the time-temperature superposition principle was used to construct a stress-lifetime master curve. Tested at 90°C, extruded Ion Power® N111-IP membrane was found to have longer lifetime than Gore™-Select® 57 and Nafion NRE-211 membranes under the same blister pressure profiles. Bimaterial specimens fabricated by bonding a piece of PEM to a substrate material were used to measure the hygral stresses, compressive and tensile, in the PEM during relative humidity cycles. The substrate material and its thickness were carefully chosen so that stresses in the PEM could be obtained directly from the curvature of the bimaterial specimen without knowing the constitutive properties of the PEM. Three commercial PEMs were tested at 80°C by cycling the relative humidity between 90% and 0% and by drying the membrane to 0%RH after submersion in liquid water. Stress histories for all three membranes show strong time-dependencies and Nafion® NRE-211 exhibited the largest tensile stress upon drying. Besides in-plane stresses, hard spots in gas diffusion media (GDM) can locally overcompress PEMs in the out-of-plane direction and cause electrical shorting. In this study, GDM samples sealed with an impermeable Kapton® film on the surface were compressed with uniform air pressure and the nonuniform displacement field was measured with a three-dimensional digital image correlation technique. Hard spots as a result of the nonuniform thickness and compressibility of the GDM were found and their severities as stress risers are evident. Locally, a nominal platen compression (similar to bipolar plate land compression) of 0.68 MPa can lead to compressive stress as large as 2.30 MPa in various hard spots that are in the order of 100s µm to 1 mm in size. / Ph. D.