Standard Transistor Array (STAR). Volume 1: Placement technique

A large scale integration (LSI) technology, the standard transistor array uses a prefabricated understructure of transistors and a comprehensive library of digital logic cells to allow efficient fabrication of semicustom digital LSI circuits. The cell placement technique for this technology involves formation of a one dimensional cell layout and "folding" of the one dimensional placement onto the chip. It was found that, by use of various folding methods, high quality chip layouts can be achieved. Methods developed to measure of the "goodness" of the generated placements include efficient means for estimating channel usage requirements and for via counting. The placement and rating techniques were incorporated into a placement program (CAPSTAR). By means of repetitive use of the folding methods and simple placement improvement strategies, this program provides near optimum placements in a reasonable amount of time. The program was tested on several typical LSI circuits to provide performance comparisons both with respect to input parameters and with respect to the performance of other placement techniques. The results of this testing indicate that near optimum placements can be achieved by use of the procedures incurring severe time penalties

THE TRANSPLANTATION AND TRANSFORMATION OF THE ENGLISH SHIRE IN AMERICA: ESSEX COUNTY, MASSACHUSETTS, 1630-1768

This study of Essex County, Massachusetts, emanates from a dissatisfaction with the disjointed and segmented histories available for the counties of colonial Massachusetts. Because little effort has been made to examine towns systematically, to place localities within the context of the larger

Commercial real estate investment and economic development in the Northeast region of the United States

The U.S. commercial real estate (CRE, henceforth) market was pummeled during the great recession. As the economy sees gradual improvements, investment continues to forge ahead from its worst slump, with fresh opportunities as construction rebounds. The debate on the relationship between real estate investment and economic growth has a long history in the economic development literature. Frequently asked questions are, should real estate investment be part of economic development strategies? Does real estate investment have more economic benefits than other investments? Should real estate investment wait until economic growth is achieved? Does real estate investment spur economic growth or, vice versa? This study tries to revisit earlier debates by attempting to understand the economic role of CRE investments, particularly retail store establishments in the Northeast region of the United States.;This study empirically estimates the interdependent relationships between growth in retail store establishments and regional economic growth. Growth in population density, employment density and per capita income are used to represent level of regional economic growth. Theoretically, the neoclassical growth model accounts for the growth effect of CRE investment as a capital injection into the economy. The investment is also considered as a potential economic stimulant since it induces additional economic activities and adds to employment. The cumulative improvements can also have favorable spillover effect to neighboring regions.;Because retail establishments\u27 size differences may influence the magnitude of the economic growth effect, establishment data are classified as being large or small, based on employment size. The study used both spatial and non-spatial analysis. The spatial model used spatial Durbin and spatial autoregressive models while the non-spatial model used a three stage least square (3SLS) simultaneous equation model.;The empirical results of this study on the relationship between CRE investment and economic development are an extension that incorporates the simultaneous relationship of retail establishments with other variables in the economic development of the region. The consideration of spatial dependency is also another novel contribution of the study.;The study concludes that indeed, growth in retail establishments plays a significant role in the economic growth process of the Northeast region of the United States. Although small retail establishments also contribute in the process of economic development, large retail establishments have a greater economic impact. Small retail establishments have a weak impact that is also statistically insignificant. This somewhat unexpected result is not inconsistent with casual observation and provides useful information for policy recommendations. Overall, the study provides information to policy makers on the economic role of both small and large retail establishments and socio-economic driving factors of the investment in the Northeast region of the U.S

Design of 28 GHz 4x4 RF Beamforming Array for 5G Radio Front-Ends

Current state of wireless infrastructure sees mass migration to higher frequencies as much of the already used spectrum is insufficient in supporting the influx of numerous users and various data intensive mobile applications. Data rates are projected to increase by an order of magnitude and harnessing the necessary bandwidth below 6 GHz is not feasible. A move to higher frequencies sees not only increased fractional bandwidth, but also significantly enhanced antenna apertures as a result of beamforming capabilities. Due to device level complications with frequencies nearing the unit gain frequency of transistor technology, high output power is seldom found, and in conjunction with severe path loss, communication links cannot be established without the usage of antenna arrays. Phased array systems offer significant upside to the traditional array implementation as it permits reconfigurable directive communication. However, Ka-Band phased arrays still struggle to arrive at a reasonable tradeoff between design complexity, cost and performance. With a divide between both organic and printed circuit board (PCB) based approaches to the development of an antenna-in-package (AiP), this thesis sides with the latter. An antenna-on-PCB variant of the AiP is developed, which implements both commercially available RF laminates and RFIC front end modules to produce a 28 GHz 4x4 RF beamforming phased array that is found to exhibit extremely low loss (-0.66 dB), adequate scan volume (+/- 45 degrees, in E and H planes) and large bandwidth (3 GHz) for a single layer, non-isolated patch antenna design. Unit cell, infinite array analysis is emphasized and lattice resizing is leveraged to obtain desired scan performance, while significantly reducing design complexity via the absence of intricate isolation enhancement techniques. In an effort to aid in application based design, the AiP is extended to application of linearization where it is found that the inclusion of dummy elements along the perimeter of the package not only serve as element pattern enhancement, but also provide reliable means of output signal capture. Negating the traditional transmitter observation receiver (TOR) architecture, the AiP design as a TOR for millimeter-wave communication proves optimistic in the quest for maximum system efficiency

Market definition study of photovoltaic power for remote villages in developing countries

The potential market of photovoltaic systems in remote village applications in developing countries is assessed. It is indicated that photovoltaic technology is cost-competitive with diesel generators in many remote village applications. The major barriers to development of this market are the limited financial resources on the part of developing countries, and lack of awareness of photovoltaics as a viable option in rural electrification. A comprehensive information, education and demonstration program should be established as soon as possible to convince the potential customer countries and the various financial institutions of the viability of photovoltaics as an electricity option for developing countries

An experimental assessment of computational fluid dynamics predictive accuracy for electronic component operational temperature

Ever-rising Integrated Circuit (IC) power dissipation, combined with reducing product development cycles times, have placed increasing reliance on the use of Computational Fluid Dynamics (CFD) software for the thermal analysis of electronic equipment. In this study, predictive accuracy is assessed for board-mounted electronic component heat transfer using both a CFD code dedicated to the thermal analysis of electronics, Flotherm, and a general-purpose CFD code, Fluent. Using Flotherm, turbulent flow modelling approaches typically employed for the analysis of electronics cooling, namely algebraic mixing length and two-equation high-Reynolds number k-e models, are assessed. As shown, such models are not specific for the analysis of forced airflows over populated electronic boards, which are typically classified as low-Reynolds number flows. The potential for improved predictive accuracy is evaluated using candidate turbulent flow models more suited to such flows, namely a one-equation SpalartAllmaras model, two-layer zonal model and two equation SST k-co model, all implemented in Fluent. Numerical predictions are compared with experimental benchmark data for a range of componentboard topologies generating different airflow phenomena and varying degrees of component thermal interaction. Test case complexity is incremented in controlled steps, from single board-mounted components in free convection, to forced air-cooled, multi-component board configurations. Apart from the prediction of component operational temperature, the application of CFD analysis to the design of electronic component reliability screens and convective solder reflow temperature profiles is also investigated. Benchmark criteria are based on component junction temperature and component-board surface temperature profiles, measured using thermal test chips and infrared thermography respectively. This data is supplemented by experimental visualisations of the forced airflows over the boards, which are used to help assess predictive accuracy. Component numerical modelling is based on nominal package dimensions and material thermal properties. To eliminate potential numerical modelling uncertainties, both the test component geometry and structural integrity are assessed using destructive and non-destructive testing. While detailed component modelling provides the à priori junction temperature predictions, the capability of compact thermal models to predict multi-mode component heat transfer is also assessed. In free convection, component junction temperature predictions for an in-line array of fifteen boardmounted components are within ±5°C or 7% of measurement. Predictive accuracy decays up to ±20°C or 35% in forced airflows using the k-e flow model. Furthermore, neither the laminar or k-e turbulent flow model accurately resolve the complete flow fields over the boards, suggesting the need for a turbulence model capable of modelling transition. Using a k-co model, significant improvements in junction temperature prediction accuracy are obtained, which are associated with improved prediction of both board leading edge heat transfer and component thermal interaction. Whereas with the k-e flow model, prediction accuracy would only be sufficient for the early to intermediate phase of a thermal design process, the use of the k-co model would enable parametric analysis of product thermal performance to be undertaken with greater confidence. Such models would also permit the generation of more accurate temperature boundary conditions for use in Physics-of-Failure (PoF) based component reliability prediction methods. The case is therefore made for vendors of CFD codes dedicated to the thermal analysis of electronics to consider the adoption of eddy viscosity turbulence models more suited to the analysis of component heat transfer. While this study ultimately highlights that electronic component operational temperature needs to be experimentally measured to quality product thermal performance and reliability, the use of such flow models would help reduce the current dependency on experimental prototyping. This would not only enhance the potential of CFD as a design tool, but also its capability to provide detailed insight into complex multi-mode heat transfer, that would otherwise be difficult to characterise experimentally

The Design of an Anti-Aliasing Filter for the Next Generation Digitiser

MeerKAT, is a 64-element radio astronomy antenna array which has been recently constructed in the Northern Cape Province of South Africa. It serves as South Africa's contribution towards the international Square Kilometre Array (SKA) project. The MeerKAT array has been designed to observe radio signals produced by celestial sources at UHF-Band, L-Band, S-Band and X-Band frequencies. The first phase of the construction included the design, development and integration of the UHF-Band, L-Band and S-band Receivers, whilst the X-band design has been superseded by the incorporation of the next phase of the SKA international project. In preparation of the next the roll-out, research is required to determine optimal wideband filter topologies suitable for direct digitisation of signal frequencies over the frequency range of 3-6 GHz. In this thesis, exploration of suitable wideband planar filters is performed, noting those with an improved out-of-band rejection. The outcome of the investigation leads into the design and development of the suitable wideband planar filter based on key performance specifications. The performance of the manufactured wideband planar filter is then compared to the theoretical design, and validated against the key performance requirements