A formulation of multidimensional growth models for the assessment and forecast of technology attributes

Danner, Travis W Georgia Institute of Technology 2006 해외박사(DDOD)

Developing technology systems requires all manner of investment---engineering talent, prototypes, test facilities, and more. Even for simple design problems the investment can be substantial; for complex technology systems, the development costs can be staggering. The profitability of a corporation in a technology-driven industry is crucially dependent on maximizing the effectiveness of research and development investment. Decision-makers charged with allocation of this investment are forced to choose between the further evolution of existing technologies and the pursuit of revolutionary technologies. At risk on the one hand is excessive investment in an evolutionary technology which has only limited availability for further improvement. On the other hand, the pursuit of a revolutionary technology may mean abandoning momentum and the potential for substantial evolutionary improvement resulting from the years of accumulated knowledge. The informed answer to this question, evolutionary or revolutionary, requires knowledge of the expected rate of improvement and the potential a technology offers for further improvement. This research is dedicated to formulating the assessment and forecasting tools necessary to acquire this knowledge. The same physical laws and principles that enable the development and improvement of specific technologies also limit the ultimate capability of those technologies. Researchers have long used this concept as the foundation for modeling technological advancement through extrapolation by analogy to biological growth models. These models are employed to depict technology development as it asymptotically approaches limits established by the fundamental principles on which the technological approach is based. This has proven an effective and accurate approach to modeling and forecasting simple single-attribute technologies. With increased system complexity and the introduction of multiple system objectives, however, the usefulness of this modeling technique begins to diminish. With the introduction of multiple objectives, researchers often abandon technology growth models for scoring models and technology frontiers. While both approaches possess advantages over current growth models for the assessment of multi-objective technologies, each lacks a necessary dimension for comprehensive technology assessment. By collapsing multiple system metrics into a single, non-intuitive technology measure, scoring models provide a succinct framework for multi-objective technology assessment and forecasting. Yet, with no consideration of physical limits, scoring models provide no insight as to the feasibility of a particular combination of system capabilities. They only indicate that a given combination of system capabilities yields a particular score. Conversely, technology frontiers are constructed with the distinct objective of providing insight into the feasibility of system capability combinations. Yet again, upper limits to overall system performance are ignored. Furthermore, the data required to forecast subsequent technology frontiers is often inhibitive. In an attempt to reincorporate the fundamental nature of technology advancement as bound by physical principles, researchers have sought to normalize multi-objective systems whereby the variability of a single system objective is eliminated as a result of changes in the remaining objectives. This drastically limits the applicability of the resulting technology model because it is only applicable for a single setting of all other system attributes. Attempts to maintain the interaction between the growth curves of each technical objective of a complex system have thus far been limited to qualitative and subjective consideration. This research proposes the formulation of multidimensional growth models as an approach to simulating the advancement of multi-objective technologies towards their upper limits. Multidimensional growth models were formulated by noticing and exploiting the correlation between technology growth models and technology frontiers. Both are frontiers in actuality. The technology growth curve is a frontier between capability levels of a single attribute and time, while a technology frontier is a frontier between the capability levels of two or more attributes. Multidimensional growth models are formulated by exploiting the mathematical significance of this correlation. The result is a model that can capture both the interaction between multiple system attributes and their expected rates of improvement over time. The fundamental nature of technology development is maintained, and interdependent growth curves are generated for each system metric with minimal data requirements. Being founded on the basic nature of technology advancement, relative to physical limits, the availability for further improvement can be determined for a single metric relative to other system measures of merit. A by-product of this modeling approach is a single n-dimensional technology frontier linking all n system attributes with time. This provides an environment capable of forecasting future system capability in the form of advancing technology frontiers. The ability of a multidimensional growth model to capture the expected improvement of a specific technological approach is dependent on accurately identifying the physical limitations to each pertinent attribute. This research investigates two potential approaches to identifying those physical limits, a physics-based approach and a regression-based approach. The regression-based approach has found limited acceptance among forecasters, although it does show potential for estimating upper limits with a specified degree of uncertainty. Forecasters have long favored physics-based approaches for establishing the upper limit to unidimensional growth models. The task of accurately identifying upper limits has become increasingly difficult with the extension of growth models into multiple dimensions. A lone researcher may be able to identify the physical limitation to a single attribute of a simple system; however, as system complexity and the number of attributes increases, the attention of researchers from multiple fields of study is required. Thus, limit identification is itself an area of research and development requiring some level of investment. Whether estimated by physics or regression-based approaches, predicted limits will always have some degree of uncertainty. This research takes the approach of quantifying the impact of that uncertainty on model forecasts rather than heavily endorsing a single technique to limit identification. In addition to formulating the multidimensional growth model, this research provides a systematic procedure for applying that model to specific technology architectures. Researchers and decision-makers are able to investigate the potential for additional improvement within that technology architecture and to estimate the expected cost of each incremental improvement relative to the cost of past improvements. In this manner, multidimensional growth models provide the necessary information to set reasonable program goals for the further evolution of a particular technological approach or to establish the need for revolutionary approaches in light of the constraining limits of conventional approaches.

A Conceptual Methodology for Assessing Acquisition Requirements Robustness against Technology Uncertainties

Chou, Shuo-Ju Georgia Institute of Technology 2011 해외박사(DDOD)

In recent years the United States has shifted from a threat-based acquisition policy that developed systems for countering specific threats to a capabilities-based strategy that emphasizes the acquisition of systems that provide critical national defense capabilities. This shift in policy, in theory, allows for the creation of an "optimal force" that is robust against current and future threats regardless of the tactics and scenario involved. In broad terms, robustness can be defined as the insensitivity of an outcome to "noise" or non-controlled variables. Within this context, the outcome is the successful achievement of defense strategies and the noise variables are tactics and scenarios that will be associated with current and future enemies. Unfortunately, a lack of system capability, budget, and schedule robustness against technology performance and development uncertainties has led to major setbacks in recent acquisition programs. This lack of robustness stems from the fact that immature technologies have uncertainties in their expected performance, development cost, and schedule that cause to variations in system effectiveness and program development budget and schedule requirements. Unfortunately, the Technology Readiness Assessment process currently used by acquisition program managers and decision-makers to measure technology uncertainty during critical program decision junctions does not adequately capture the impact of technology performance and development uncertainty on program capability and development metrics. The Technology Readiness Level metric employed by the TRA to describe program technology elements uncertainties can only provide a qualitative and non-descript estimation of the technology uncertainties. In order to assess program robustness, specifically requirements robustness, against technology performance and development uncertainties, a new process is needed. This process should provide acquisition program managers and decision-makers with the ability to assess or measure the robustness of program requirements against such uncertainties. A literature review of techniques for forecasting technology performance and development uncertainties and subsequent impacts on capability, budget, and schedule requirements resulted in the conclusion that an analysis process that coupled a probabilistic analysis technique such as Monte Carlo Simulations with quantitative and parametric models of technology performance impact and technology development time and cost requirements would allow the probabilities of meeting specific constraints of these requirements to be established. These probabilities of requirements success metrics can then be used as a quantitative and probabilistic measure of program requirements robustness against technology uncertainties. Combined with a Multi-Objective Genetic Algorithm optimization process and computer-based Decision Support System, critical information regarding requirements robustness against technology uncertainties can be captured and quantified for acquisition decision-makers. This results in a more informed and justifiable selection of program technologies during initial program definition as well as formulation of program development and risk management strategies. To meet the stated research objective, the ENhanced TEchnology Robustness Prediction and RISk Evaluation (ENTERPRISE) methodology was formulated to provide a structured and transparent process for integrating these enabling techniques to provide a probabilistic and quantitative assessment of acquisition program requirements robustness against technology performance and development uncertainties. In order to demonstrate the capabilities of the ENTERPRISE method and test the research Hypotheses, an demonstration application of this method was performed on a notional program for acquiring the Carrier-based Suppression of Enemy Air Defenses (SEAD) using Unmanned Combat Aircraft Systems (UCAS) and their enabling technologies. The results of this implementation provided valuable insights regarding the benefits and inner workings of this methodology as well as its limitations that should be addressed in the future to narrow the gap between current state and the desired state.

Designing high-performance microprocessors in 3-dimensional integration technology

Puttaswamy, Kiran Georgia Institute of Technology 2007 해외박사(DDOD)

In this dissertation, we demonstrate the impact of a new emerging technology called 3D-integration technology on microprocessors. 3D-integration technology stacks transistors in the vertical dimension in addition to the conventional horizontal plane. The additional degree of connectivity in the vertical dimension enables circuit designers to replace global wires with short vertical interconnects, thus reducing delay, power consumption, and area. To adapt planar microarchitectures to 3D-integrated designs, we study several building blocks that together comprise a substantial portion of a processor's total transistor count. In particular, we focus our attention on three basic circuit classes: static random access memory circuits, associative logic circuits, and data processing circuits. We propose different 3D-integrated circuit designs to deal with the constraints of the conventional planar technology. Based on the 3D-integrated circuits, we propose high-performance 3D-integrated microprocessors and evaluate the impact on performance, power, and temperature. We demonstrate two different approaches to improve performance: clock speed improvement and IPC improvement. We demonstrate the simultaneous benefits of the 3D-integration and highlight the power density issue related to the 3D-integration technology. Next, we propose novel microarchitectural techniques to address the challenge of power density. We demonstrate that microarchitecture-level techniques can effectively control the power density in the 3D-integrated processors. The 3D-integrated processors provide a significant performance benefit over the planar processors while simultaneously reducing the total power. One of the key contributions of this dissertation is the temperature analysis that shows that the worst-case temperatures on the 3D-integrated processors can be effectively controlled using microarchitecture level techniques. The 3D-integration technology may extend the applicability of Moore's law for a few more technology generations.

Anisotropic structure and electrical properties of intrinsically conducting polymers

Ou, Runqing Georgia Institute of Technology 2002 해외박사(DDOD)

Two conducting polymers, polyaniline (PANI) and poly(phenylene vinylene) (PPV), were employed in this research to study the relationship between the anisotropic structure and the electrical properties of conducting polymers. The anisotropic structure of the conducting polymers were determined by three independent nondestructive characterization techniques: X-ray diffraction, infrared dichroism, and three dimensional refractive index measurement using a modified prism waveguide coupler. The electrical properties of the conducting polymers were studied by AC impedance spectroscopy. PPV films fabricated using the precursor route, stretched at 60°C and converted to PPV at fixed length at 200°C at Clemson University, were used for this investigation at Georgia Institute of Technology. Structural study of PPV reveals that the unstretched PPV film has a planar structure, that it is partially crystalline, and that the a axis of the PPV crystal is normal to the film plane. Stretching of the film converts the planar structure to a uniaxial structure. Impedance spectroscopy of the PPV films shows two relaxations, the lower frequency relaxation being related to contact and the higher frequency relaxation being related to the PPV film. Both in-plane conductivity values are higher than the through-plane conductivity. PANI films were cast from N, N<super>′</super>-dimethyl propylene urea (DMPU) solution and stretched to different draw ratios at Clemson University. X-ray diffraction indicates that the films are noncrystalline and remain noncrystalline after stretching. The neutral PANI, when doped by HCl becomes partially crystalline. Impedance measurements were made on unstretched and stretched PANI films doped by HCl. For the unstretched film, the impedance of films with different doping level was studied. A conductivity relaxation was observed for both the in-plane measurement and through plane measurement. The relaxation frequency shifts to higher frequency with increasing doping level. The conductivity dramatically increases with doping level and then levels off. The in-plane conductivity is greater than the throughplane conductivity. The impedance of stretched HCl doped PANI films was studied at a fixed doping level. The in-plane conductivity is greater than the through-plane conductivity. The conductivity anisotropy increases with increasing orientation.

How do prizes induce innovation? Learning from the Google Lunar X-prize

Kay, Luciano Georgia Institute of Technology 2011 해외박사(DDOD)

This research investigates prizes and the means by which they induce innovation. In particular, four questions that are relevant from the viewpoint of both scientific inquiry and policy-making are addressed: (1) How do different types of incentives weigh in the overall motivation of prize entrants? (2) What are the characteristics of prize R&D activities and how do they differ from traditional industry's R&D activities? (3) What are the characteristics of the prize technology outputs and how do they relate to the characteristics of prize entrants and their R&D activities? (4) Do prizes spur innovation over and above what would have occurred anyway?. This research uses an empirical, multiple case-study methodology and multiple data sources to investigate three cases of recent aerospace technology prizes: a main case study, the Google Lunar X Prize (GLXP) for robotic Moon exploration; and two pilot cases, the Ansari X Prize (AXP) for the first private reusable manned spacecraft and the Northrop Grumman Lunar Lander Challenge (NGLLC) for flights of reusable rocket-powered vehicles. This research also introduces an innovation model to investigate prizes that focuses on the competition as unit of analysis and articulates internal and external factors that can potentially explain the effect of prizes on innovation. The investigation unveils the dynamics of prizes and contributes a better understanding of their potential and disadvantages in a context in which more traditional mechanisms are used to induce innovation. The incentives offered by prizes attract entrants with diverse characteristics, including unconventional entrants---individuals and organizations generally not involved with the prize technologies. Entrants are generally attracted by the non-monetary benefits of participation (e.g. reputation, visibility, opportunity to participate in technology development and accomplish other personal and organizational goals) and the potential market value of the technologies involved in competitions. Many more volunteers, collaborators, and partners also participate---though only indirectly---and support official entries as they also perceive opportunities to accomplish personal and organizational goals. The monetary reward is not as important as other prize incentives, yet it is still important to position and disseminate the idea of the prize. Prizes can induce increasing R&D activities and re-direct industry projects to target diverse technological goals, yet the evolution of prize competitions is generally difficult to anticipate. The overall organization of prize R&D activities depends on entrant-level factors such as goals, strategies, and resources, and can only be indirectly influenced by setting specific competition rules. The most remarkable characteristic of prize R&D activities is their interaction with fundraising efforts which, in some circumstances, may constrain the activities of entrants. Prizes can also selectively focus the advancement of technologies at different levels of maturity (e.g. experimental research, incremental developments, commercialization,) yet the quality of the technological outputs is also generally difficult to anticipate and depends on entrant-level factors as well. Prizes can also induce innovation over and above what would have occurred anyway, yet their overall effect depends significantly on the characteristics of the prize entrants and the evolution of the context of the competition. The ability of prizes to induce innovation is larger when there are larger prize incentives, more significant technology gaps implicit in the prize challenge, and open-ended challenge definitions. Moreover, prizes can induce technological breakthroughs but complementary incentives (e.g. commitments to purchase technology) or support (e.g. seed funding) may be needed in some circumstances. This research shows that prizes are a more complex mechanism and their investigation requires analyzing entrant- and context-level factors generally not considered by the literature. Prizes complement and not replace patents and other incentive mechanisms. The ability of entrants to retain IP rights on their technologies enables the R&D process and hybrid prize schemes that include financial support for qualified entrants (e.g. R&D grants) or commitment to purchase prize technologies (e.g. procurement contracts) are optional designs for these competitions. Prizes are only one of the forms of intervention to stimulate technological innovation, but are particularly appropriate to, for example, explore new, experimental methods and technologies that imply high-risk R&D induce technological development to break critical technological barriers; accelerate technological development to achieve higher performance standards; and, accelerate diffusion, adoption, and/or commercialization of technologies. Prizes can selectively target certain technologies, R&D performers and geographic areas, and also leverage funding significantly due to their widespread, decentralized impact. They involve, however, higher programmatic risks than other more traditional mechanisms and their routine use, and/or challenge definitions that overlap, can weaken the incentive power of the mechanism. Successful implementation of competitions requires many parameters to be properly set. (Abstract shortened by UMI.).

The economics of enterprise transformation: An analysis of the defense acquisition system

Pennock, Michael J Georgia Institute of Technology 2008 해외박사(DDOD)

Despite nearly 50 years of attempts at reform, the US defense acquisition system continues to deliver weapon systems over budget, behind schedule, and with performance shortfalls. A parade of commissions, panels, and oversight organizations have studied and restudied the problems of government acquisition with the objective of transforming the defense acquisition enterprise, yet the resulting legislative and procedural changes have yielded little, if any, benefit. Thus, the obvious question is why has acquisition reform failed? Three potential contributors were identified in the literature: misalignment of incentives, a lack of a systems view, and a lack of objective evaluation criteria. This dissertation attempts to address each of these problem areas. First, I consider the issue of incentivization in the context of defense technology policy. A frequent criticism of defense acquisition programs is that they tend to employ risky, immature technology that increases the cost and duration of acquisition efforts. To combat this problem the Department of Defense rewrote their acquisition regulations to encourage a more evolutionary approach to system development. Nominally, this requires the use of mature technologies, but studies have revealed that acquisition programs continue to use immature technologies in spite of the new policies. To analyze this issue, the defense acquisition cycle was modeled as a stochastic process. Then, assuming that each acquisition program serves a diverse set of stakeholders, game theory was applied to show that the stable solution is to employ immature technology. It turns out that there is a tragedy of the commons at work in which the acquisition program serves as the common resource for each of the stakeholder groups to achieve its objectives. Since there is no cost to using the resource, there is a tendency to overexploit it. The result is an outcome that is worse than if there had been a coordinated solution. Thus, the rational actions of stakeholders will lead to a contradiction of acquisition policy. Consequently, if the Department of Defense expects adherence to its evolutionary acquisition policy it must either strictly enforce technology maturity requirements or else realign incentives with desired outcomes. Second, I evaluate cost and performance implications of the most recent defense acquisition transformation initiative, evolutionary acquisition. Proponents suggest that evolutionary acquisition will lower acquisition program costs, shorten delivery times, and improve the performance of fielded systems through the use of shorter and more incremental acquisition cycles. Supporting arguments focus on the impact of evolutionary acquisition on individual programs but fail to consider the defense acquisition enterprise as a system. To address this shortcoming, I analyze the impact of evolutionary policies through the use of a discrete event simulation of the entire defense acquisition system. It was found that while there should be an increase in the performance of fielded systems under evolutionary acquisition policies, the cost of operating the defense acquisition system as a whole does not inherently decrease. This is because the shorter acquisition cycles created by evolutionary polices mean that the overhead costs of each acquisition cycle are incurred more frequently. If these overhead costs do not decline sufficiently, the net cost to operate the acquisition system rises. This finding demonstrates the importance of considering the entire acquisition system before implementing a new policy. Finally, I address the lack of objective evaluation criteria by developing a method to value acquisition process improvements monetarily. This is accomplished through the combination of price indices and options analysis. Since the US government is a non-profit entity, traditional cash flow based valuation methods are not applicable. Instead, the use of price indices captures the changes in the government's buying power induced by acquisition reforms. This may be converted into an equivalent augmented budget stream that allows traditional investment evaluation tools to be applied. An additional advantage of the buying power method is that it captures the impact of the economies of scale inherent in the production of military systems. The augmented budget stream serves as the basis for applying options analysis, which properly accounts for the risk mitigating effects of staging. A comparison of this new method with more traditional methods reveals that only considering cost savings can significantly undervalue acquisition improvement opportunities, and even small improvements can have large returns.

Active identification and control of aerodynamic instabilities in axial and centrifugal compressors

Krichene, Assad Georgia Institute of Technology 2002 해외박사(DDOD)

In this thesis, it is experimentally shown that dynamic cursors to stall and surge exist in both axial and centrifugal compressors using the experimental axial and centrifugal compressor rigs located in the School of Aerospace Engineering at the Georgia Institute of Technology. Further, it is shown that the dynamic cursors to stall and surge can be identified in real-time and they can be used in a simple control scheme to avoid the occurrence of stall and surge instabilities altogether. For the centrifugal compressor, a previously developed real-time observer is used in order to detect dynamic cursors to surge in real-time. An off-line analysis using the Fast Fourier Transform (FFT) of the open loop experimental data from the centrifugal compressor rig is carried out to establish the influence of compressor speed on the dynamic cursor frequency. The variation of the amplitude of dynamic cursors with compressor operating condition from experimental data is qualitatively compared with simulation results obtained using a generic compression system model subjected to white noise excitation. Using off-line analysis results, a simple control scheme based on fuzzy logic is synthesized for surge avoidance and recovery. The control scheme is implemented in the centrifugal compressor rig using compressor bleed as well as fuel flow to the combustor. Closed loop experimental results are obtained to demonstrate the effectiveness of the controller for both surge avoidance and surge recovery. The existence of stall cursors in an axial compression system is established using the observer scheme from off-line analysis of an existing database of a commercial gas turbine engine. However, the observer scheme is found to be ineffective in detecting stall cursors in the experimental axial compressor rig in the School of Aerospace Engineering at the Georgia Institute of Technology. An alternate scheme based on the amplitude of pressure data content at the blade passage frequency obtained using a pressure sensor located (in the casing) over the blade row is developed and used in the axial compressor rig for stall and surge avoidance and recovery. (Abstract shortened by UMI.).

A methodology for technology identification, evaluation, and selection in conceptual and preliminary aircraft design

Kirby, Michelle Rene Georgia Institute of Technology 2001 해외박사(DDOD)

The changing global socio-economical and political environment is creating a paradigm shift in the aerospace industry. This paradigm shift calls for solutions that are beyond evolutionary databases and demands consideration of all aspects of the system's life cycle. The shift implies that a new means of evaluating the “goodness” of a system must be established and requires inclusion of three elements. The elements are as follows: consideration of the product life cycle in the early phases of design, new design methods to account for multiple criteria and uncertainty, and breakthrough technologies to meet aggressive performance and economic objectives of the future. A new design method for complex systems was created as a response to the paradigm shift and was achieved with the use of statistical and probabilistic methods, including Response Surface Methods and Monte Carlo Simulations. The method accounts for the multi-criteria problem in the presence of design, operational, and technological uncertainty while allowing for the infusion and subsequent affordability assessment of immature technologies. The design method includes a forecasting environment whereby the decision-maker has the ability to easily assess and trade-off the impact of various technologies without sophisticated and time-consuming mathematical formulations. This objective was achieved by employing the use of Morphological analysis, forecasting analogies and techniques, and Multi-Attribute Decision Making techniques. Through the execution of the method, a family of design alternatives for a set of customer requirements can be identified and assessed subjectively or objectively. This method allows for increased knowledge, reduced committed costs and increased design freedom leverage to produce high quality and competitive cost systems in a systematic and comprehensive manner and is called the Technology Identification, Evaluation, and Selection, or TIES, method. The TIES method was demonstrated on a High Speed Civil Transport concept. This vehicle was chosen as a benchmark for the method due to the technically challenging customer requirements and the need for revolutionary advances over present day technological capabilities to obtain feasible configurations. The TIES method established the need and the product specifications and identified the most suitable set of technologies to satisfy all customer requirements in a probabilistic design setting.

Reliable middleware framework for RFID system

Ahmed, Nova Georgia Institute of Technology 2010 해외박사(DDOD)

The reliability of RFID systems depends on a number of factors including: RF interference, deployment environment, configuration of the readers, and placement of readers and tags. While RFID technology is improving rapidly, a reliable deployment of this technology is still a significant challenge impeding wide-spread adoption. This research investigates system software solutions for achieving a highly reliable deployment that mitigates inherent unreliability in RFID technology. We have considered two different problem domains for large scale RFID deployment. One is item tracking and the other is guidance-monitoring. The basic contribution of our work is providing novel middleware solution that is able to serve the application taking into account the inherent unreliability of RFID technology. Our path abstraction that uses the physical flow of data as an ally to generate a logical system level flow enhances the performance in many ways. The contributions of this dissertation are summarized below. Defining novel system architecture for item tracking applications: We have defined a system architecture referred to as Reliable Framework for RFID (RF2ID) that takes into account the unreliability of RFID devices and provides a scalable, reliable system architecture for item tracking applications. It uses a distributed system abstraction named Virtual Reader (VR) that handles RFID data in different geographic locations. Virtual Path (VPath) is the abstraction that creates channels among the VRs and facilitates a data flow oriented data management in the system. Implementation of RF2ID: We have implemented RF2ID that is able to incorporate physical RFID devices as well as emulated devices for scalability study taking into account various real world challenges of large scale RFID deployment. Load Shedding Based Resource Management: RF2ID requires a mechanism to handle unexpected system load in the presence of asynchronous arrival of data items. Space based load shedding and time based load shedding techniques are used in RF2ID. The basic idea is to exploit the VR and Vpath abstraction to intelligently share the load among the VRs in the presence of high system load, and yet provide some guaranteed Quality of Service (QoS). Architecture for GuardianAngel: We define an architecture for an indoor pervasive environment which provides novel system abstraction and communication framework. The layered architecture has distributed computational elements known as the virtual station (VS) that are in charge of serving different regions of the environment. The Mobile Objects (MO) are the physical and logical entities that use sensing device and traverse the environment. The environment itself is tagged with RFID. The MO uses its sensing device to make guidance decisions locally. The VS keeps status information of MOs and keeps coarse grained information of the MO over time and space providing a virtual location for each MO. Implementation of GuardianAngel: We have implemented the GuardianAngle system as defined by the architecture. We have used a testbed that uses real RFID readers and tags in the pervasive environment in a limited laboratory setup. We have also developed a distributed system setup using emulated tags for a scalability study of the proposed architecture. We have also implemented a prototype application, to test its feasibility in the real world. Evaluation of the system: We have conducted extensive evaluation using the real RFID testbed as well as scalability study using emulated readers and tags. The evaluation using the real RFID tags and readers gives us the credibility of the system under various environmental considerations. The large scale experimentations provide us with scalability and feasibility study to strengthen our limited resource study using real RFID testbed. (Abstract shortened by UMI.).

Technology-independent CMOS op amp in minimum channel length

Sengupta, Susanta Georgia Institute of Technology 2004 해외박사(DDOD)

The performance of analog integrated circuits is dependent on the technology. Digital circuits are scalable in nature, and the same circuit can be scaled from one technology to another with improved performance. But, in analog integrated circuits, the circuit components must be re-designed to maintain the desired performance across different technologies. Moreover, in the case of digital circuits, minimum feature-size (short channel length) devices can be used for better performance, but analog circuits are still being designed using channel lengths larger than the minimum feature sizes. The research in this thesis is aimed at understanding the impact of technology scaling and short channel length devices on the performance of analog integrated circuits. The operational amplifier (op amp) is chosen as an example circuit for investigation. The performance of the conventional op amps are studied across different technologies for short channel lengths, and techniques to develop technology-independent op amp architectures have been proposed. In this research, three op amp architectures have been developed whose performance is relatively independent of the technology and the channel length. They are made scalable, and the same op amp circuits are scaled from a 0.25 mum CMOS onto a 0.18 mum CMOS technology with the same components. They are designed to achieve large small-signal gain, constant unity gain-bandwidth frequency and constant phase margin. They are also designed with short channel length transistors. Current feedback, gm boosted, CMOS source followers are also developed, and they are used in the buffered versions of these op amps.