The panel zone region in columns of seismic resistant steel moment frames are subject to very high shear forces during earthquake loading. Doubler plates are often used to increase the stiffness and strength of the panel zone. The methods and details used to attach doubler plates to columns can affect seismic performance of the panel zone and can also affect cost. The research reported in this thesis was aimed at developing an improved understanding of the advantages and disadvantages of various approaches for detailing and welding doubler plates to columns and how various details perform under cyclic inelastic loading. An extensive series of finite element analyses were conducted to study doubler plate attachment details. Both a shallow W14x398 column and a deep W40x264 column were studied in this research. This thesis provides a detailed description of the finite element modeling techniques used for the research and presents the results of an extensive series of analyses examining a wide variety of issues related to doubler plate design and detailing. / text

Master of Science / Architectural Engineering and Construction Science / Donald J. Phillippi / Special steel moment frames are one of the most common systems used to resist high seismic forces. Well-proportioned moment resisting connections are essential. Special steel moment frame connections must be capable of transferring moment and shear forces that are developed in the beams to the column. These connections must be designed as a highly ductile element in order to dissipate extensive energy thus undergo inelastic deformations. Doubler plates and continuity plates have been recommended by several design codes and standards in order to strengthen the column web and prevent the inelastic deformation of the panel zone due to high shear stress concentrations. However, doubler plates and continuity plates are very expensive due to the large amount of detailing and welding requirements. Furthermore, the extensive welding may affect the properties of the steel in which it may cause shrinkage, lower potential notch toughness and cracking. In any of these cases, there is high potential of losing the desirable inelastic performance required for these SMF. This report investigates the design of the special steel moment frame connections thus eliminating the use of doubler and continuity plates in these connections. Tables are provided that show all steel W-Shape beam sizes with all the adequate steel W-Shape column sizes used in special steel moment frames without the use of doubler and continuity plates in frame connections.

Three high performance circuits for a low power supply DRAM¡¦s are presented in this thesis. First, a modified multi-stage sense amplifier is proposed, that utilizes the auxiliary transmission gate and charge recycling technique. The auxiliary NMOS transistor of the multi-stage sense amplifier is replaced by the transmission gate to improve the sensing speed. In addition, the charge recycling technique is used to reduce the power dissipation of multi-stage sense amplifier. It improves the sensing time by 6.1ns (24.4%) compared to that of the conventional multi-stage sense amplifier and the power saving percentage of 25.6% compared to that of the conventional one. Second, an improved Standby Power Reduction (SPR) Circuit is reported. The capacitor boosting technique is utilized in our proposed Static Current Cut-off Standby Power Reduction (SCCSPR) Circuit, which turns off the always-on MOS transistor of SPR circuit. The power consumption is 30.9% reduced by our design compared to that of the conventional SPR circuit. Third, an improved voltage doubler is developed. The indirect switch is utilized in our proposed circuit, it provides larger gate source bias applied to the PMOS pass transistor. Thus, the current drivability is arisen and the pumping speed is improved as well. In the 2V supply voltage, the pumping speed of our modified voltage doubler is arisen about 18.6% compared to that of the conventional voltage doubler. These high performance circuits in this thesis are applied in a 1-Kbit DRAM circuits. A data access time of 36ns and total power consumption 52.58mW are attained when the supply voltage is 2V. The access time of 10.3ns (22.2%) and power consumption of 6.44mW (11%) are reduced compared to that of the conventional DRAM.

In steel moment resisting frames, the region of the column located within the beam-column joint is known as the panel zone. When a steel moment resisting frame is subjected to lateral load, due to wind or seismic loads, the panel zone is subject to high shear. In some cases, the shear in the panel zone is sufficiently high that the panel zone must be reinforced to increase its stiffness and/or strength. This is normally accomplished by welding doubler plates to the column in the panel zone region. Doubler plates can be a costly feature in steel moment resisting frames because of the substantial amount of welding involved. There has been a large amount of past research that has investigated the required shear strength and stiffness of the panel zone region to establish a basis for sizing doubler plates. However, very little past research has investigated the details of attaching doubler plates to columns. These attachment details can have a significant influence on the structural performance of panel zone and on cost. The overall goal of this research was to conduct preliminary finite element studies that provide insight into several key issues related to the attachment of doubler plates to columns and to identify issues that require further research. The research involved finite element modeling of a simplified representation of beam-to-column joint subjected to monotonic loading. A total of twenty-one analysis cases with different doubler plate attachment details were studied. Issues that were investigated included the effect of welding different edges of the doubler plate to the column (horizontal edges only, vertical edges only, and all four sides), the effect of extending the doubler plate beyond the panel zone region, and the effect of providing two thinner doubler plates of equivalent total thickness on both sides of the column web instead of one thick doubler plate on one side of the column web. In addition, the forces developed in the doubler plate welds were computed from the finite element analysis and compared with current building code requirements for the design of these welds. Observations and preliminary design recommendations on these issues are provided in this thesis, along with recommendations for further research. / text

A number of recent research studies have investigated the performance of panel zones in seismic-resistant steel Special Moment Resisting Frames (SMF). These recent studies investigated various options for attaching doubler plates to the column at beam-column joints in SMF for purpose of increasing the shear strength of the panel zone. This previous work was primarily focused on doubler plates that extend beyond the top and bottom of the attached beams, and considered cases both with and without continuity plates. As an extension to this previous research, this thesis explores the situation when a doubler plate is fitted between the continuity plates. The objective of this research was to evaluate various options for welding fitted doubler plates to the column and continuity plates through the use of finite element analysis, and to provide recommendations for design. The development and validation of the finite element model are described, along with the results of an extensive series of parametric studies on various panel zone configurations and attachment details for fitted doubler plates. Based on the results of these analyses, recommendations are provided for design of welds used for attaching fitted doubler plates in the panel zone of SMF systems. / text

This thesis presents results of research aimed at developing an improved understanding of the behavior of column panel zones reinforced with doubler plates in seismic resistant steel moment frames. A primary goal of the research was to develop data to support the development of improved design guidelines for welding doubler plates to columns, with and without the presence of continuity plates. The research addressed several issues and questions related to welding and detailing of doubler plates. This included evaluation of the effects of welding the top and bottom of the doubler plate in addition to the vertical edges, the effects of extending the doubler plate beyond the panel zone, and the impact of welding a continuity plate to a doubler plate. These issues were investigated through detailed finite element models of a simplified representation of the panel zone region, subjected to monotonic loading. The results of the research suggest that, in general, there is little benefit in welding the top and bottom edges of a doubler plate if the vertical edges are welded, particularly in terms of overall panel zone strength and stiffness. However, the top and bottom welds provide some benefit in reducing stresses on the vertical welds. The results also suggest that extending the doubler plate above and below the panel zone has little benefit for heavy columns of shallow depth, such as the W14x398 considered in this analysis. However, extending the doubler plate did result in approximately a 10-percent increase in panel zone strength for deeper columns, such as the W40x264 considered in this analysis. Finally, the results showed that welding a continuity plate directly to a doubler plate had no adverse effects on the doubler plate in terms of increased forces or stresses. Interestingly, welding the continuity plate to the doubler plate simply changed the load path for transfer of load from the beam flange to the column web and doubler plate, but did not change the stresses in the doubler plate. Further research is needed to validate these findings for more accurate representations of the panel zone region of the column and for cyclic loading. / text

Increased challenges in CMOS scaling have motivated the development of alternatives to silicon circuit technologies, including graphene transistor development. In this work, we present a circuit simulator model for graphene FETs, developed to both fit measured data and predict new behaviors, motivating future research. The model is implemented in Agilent ADS, a circuit level simulator that is commonly used for non-standard transistor technologies, for use with parameter variation analyses, as well as easy integration with CMOS design kits. We present conclusions drawn from the model, including analyses on the effects of contact resistance and oxide scaling. We have also derived a quantum-capacitance limited model, used to intuit intrinsic behaviors of graphene transistors, as well as outline upper bounds on performance. Additionally, the ideal frequency doubler has been examined and compared with graphene, and performance limits for graphene frequency multipliers are elucidated. Performance as a demodulator is also discussed. We leverage this advancement in modeling research to advance circuit- and system-level research using graphene transistor technology. We first explore the development of a GHz planar carbon antenna for use on an RF frontend. This research is further developed in work towards the first standalone carbon radio on flexible plastics. A front end receiver, comprised of an integrated carbon antenna, transmission lines, and a graphene transistor for demodulation, are all fabricated onto one plastic substrate, to be interfaced with speakers for a full radio demo. This complete system will motivate further research on graphene-on-plastic systems. / text

This Master's Thesis deals with a design of L-band receiver front-end. In the concrete the receiver is designed for receiving signals of frequency band 1,3 GHz. All particular blocks from low noise amplifier to intermediate frequency amplifier and frequency doubler in LO input are described, designed and simulated in program Ansoft. The part of this Master's Thesis is aimed to construct a working front-end receiver and to measure its basic parameters.

In this thesis the development of a high efficiency harmonic re-radiator, consisting of a diode doubler and conjugate-matched receive and transmit antennas, is described. Diode-based frequency multipliers and rectifiers, coupled with antennas, are of interest for quasi-optical applications, for energy-scavenging and for sensing applications. The device studied operates by receiving an interrogating signal at a frequency of 1.3 GHz and re-radiating a signal at 2.6 GHz. The primary goal of this research was to develop a passive, miniature and effective frequency doubler integrated with planar antennas. The system is referred to as a frequency doubling reflectenna, (FDR). Prediction of accurate performance was achieved by employing precise modeling and measurement methods. The FDR can be utilized in data collection applications. The footprint of the FDR is occupied primarily by the receive and transmit antennas. Therefore, a significant portion of the research focused on the development of compact and efficient planar antennas, which would provide for a miniature FDR. A first-generation FDR design was designed, which utilized quarter-wavelength shorted microstrip patch antennas. The choice of antennas provided a small prototype with dimensions equal to 44 mm by 17 mm. In order to further reduce the size of the harmonic re-radiator, meandered planar antennas were investigated and optimized for efficient operation. A second-generation FDR design, which utilized meandered microstrip patch antennas, was produced and a size reduction of 75% was achieved. Both first- and second-generation harmonic re-radiator designs were designed for low input power operation and provided maximum measured conversion efficiencies of approximately 4.5% and 1.8%, with the input to the diode doubler at -14.5 and -17.5 dBm, respectively. Re-configurable microwave devices, which dynamically operate at different frequencies, are often desirable for sensing applications. Therefore, to conclude this research, a tunable FDR was realized using a semiconductor varactor that provided the dynamic capacitance required for the tunability.

This thesis presented the research, design and fabrication associated with a unique application of rectenna technology combined with lock-in amplification. An extremely low-power harmonic transponder is conjoined with an interrogator base-station, and utilizing coherent demodulation the Remote Lock-In Amplifier (RLIA) concept is realized. Utilizing harmonic re-radiation with very low-power input, the 1st generation transponder detects a transmitted interrogation signal and responds by retransmitting the second harmonic of the signal. The 1st generation transponder performs this task while using no additional power besides that which accompanies the wireless signal. Demonstration of the first complete configuration provided proof of concept for the RLIA and feasibility of processing relevant information under "zero" power operating conditions with a remote transponder. Design and fabrication of a new transponder where the existing zero-bias transponder was modified to include a DC bias to the diode-based frequency doubler is presented. Applied bias voltage directly changed the impedance match between the receiving 1.3 GHz antenna and the diode causing a change in conversion loss. Testing demonstrated that a change in conversion loss induces an amplitude modulation on the retransmission of the signal from the transponder. A test of bias sweep at the optimal operating frequency was performed on the 2nd generation transponder and it was seen that a change of ~ 0.1 V in either a positive or negative bias configuration induced an approximate 15 dB change in transponder output power. A diode-integrated radar detector is designed to sense microwaves occurring at a certain frequency within its local environment and transform the microwave energy to a DC voltage proportional the strength of the signal impinging on its receiving antenna. The output of the radar detector could then be redirected to the bias input of the 2nd generation transponder, where this DC voltage input would cause a change in conversion loss and modulate the retransmitted interrogation signal from the transponder to the base station. When the base station receives the modulated interrogation signal the information sensed by the radar detector is extracted. Simulations and testing results of the fabricated radar detector demonstrate capability of sensing a signal of approximately -53.3 dBm, and accordingly producing a rectified DC voltage output of 0.05 mV. A comparison is made between these findings and the transponder measurements to demonstrate feasibility of pairing the radar detector and the 2nd generation transponder together at the remote sensor node to perform modulation of interrogation signals.