Performance analysis of a solar-assisted swimming pool heating system

This paper deals with feasibility studies for a solar-assisted heating system for the University of Miami's Aquatic Center using the simulation program TRNSYS. The Aquatic Center is composed of an outdoor olympic size swimming pool and locker room building. The solar heating is accomplished by employing hot water generated by heat exchange with the solar collector working fluid. Two thermal storage tanks are employed for the collector and domestic use. The performance of the system is analyzed from both thermodynamic and economic standpoints and general conclusions are reached.     

SiGe: An attractive material for post-CMOS processing of MEMS

This work gives an overview of the different developments for silicon germanium (Si_1−xGe_x) from a MEMS post-processing perspective. First, the maximum processing temperature that does not introduce any damage or degradation into the standard characteristics of the CMOS driving electronics is specified. Then, the optimal type of silicon and germanium gas sources and deposition technique that results in an economical process are identified. Next, the selection criteria for a low thermal budget doping method and doping species are discussed. Finally, the advantage and disadvantage for the different approaches implemented for enhancing the physical properties of poly Si_1−xGe_x at a CMOS backend compatible temperature are highlighted. It is shown that the optimal method depends on the application requirements and the CMOS technology used for realizing the driving electronics.     

Long Duration Persistent Photocurrent in 3 nm Thin Doped Indium Oxide for Integrated Light Sensing and In-Sensor Neuromorphic Computation

Miniaturization and energy consumption by computational systems remain major challenges to address. Optoelectronics based synaptic and light sensing provide an exciting platform for neuromorphic processing and vision applications offering several advantages. It is highly desirable to achieve single-element image sensors that allow reception of information and execution of in-memory computing processes while maintaining memory for much longer durations without the need for frequent electrical or optical rehearsals. In this work, ultra-thin (<3 nm) doped indium oxide (In₂O₃) layers are engineered to demonstrate a monolithic two-terminal ultraviolet (UV) sensing and processing system with long optical state retention operating at 50 mV. This endows features of several conductance states within the persistent photocurrent window that are harnessed to show learning capabilities and significantly reduce the number of rehearsals. The atomically thin sheets are implemented as a focal plane array (FPA) for UV spectrum based proof-of-concept vision system capable of pattern recognition and memorization required for imaging and detection applications. This integrated light sensing and memory system is deployed to illustrate capabilities for real-time, in-sensor memorization, and recognition tasks. This study provides an important template to engineer miniaturized and low operating voltage neuromorphic platforms across the light spectrum based on application demand.     

Dynamic behaviour of radio channels due to trans-horizon propagation mechanisms

To study the propagation mechanisms of trans-horizon radio links, the authors propose an event-based approach. Data from one year captured on a trans-horizon link of 156 km are divided into different groups according to the signal amplitude signature of the chart recordings. The propagation mechanisms for each group are investigated using the cross-correlation between received signal amplitudes along the same path. These amplitudes are obtained using two different transmitter antenna heights.<>     

Overview of wideband packet protocols

Wideband packet networks operate at rates equal to, or higher than, 64 kb/s, but lower than the basic broadband rate of 150 Mb/s, on cables or satellite links. Wideband packet protocols are the transmission protocols for these networks. They define open interfaces that can be used for public and private ISDNs. The protocols are defined in CCITT Recommendations G.764 and G.765. This paper describes the objectives of the wideband protocols, and how the objectives were achieved.     

Mapping 3-D IIR digital filter onto systolic arrays

We present here an efficient systolic implementation for 3-D IIR digital filters. The systolic implementation is obtained by using an algebraic mapping technique. This new mapping technique gives us the choice to mix pipelined variables and broadcast variables. We also determine, through the mapping method, the buffer sizes, the direction of variables propagations and the data feeding and extracting points. The resultant systolic array implementation is a modular structure composed of 2-D filter modules connected by simple buffers. This new systolic implementation is regular, modular and amenable to VLSI Implementation.     

A novel approach for the modeling of advanced photovoltaic devices using the SILVACO/ATLAS virtual wafer fabrication tools

In this paper a new method for developing a realistic model of any type of solar cell is presented. Taking into account the high cost of research and experimentation involved with the development of advanced cells, we present here this novel methodology. In our opinion, the introduction of this modeling technique to the photovoltaic community will prove to be of great importance in aiding in the design and development of advanced solar cells. Two models of a single GaAs and an InGaP/GaAs/Ge multi-junction solar cell are prepared and are fully simulated. The major stages of the process are explained and the simulation results are compared to published experimental data to demonstrate the accurate results produced by the model utilizing this technique. The flexibility of the proposed methodology is illustrated and example results are shown throughout the whole process, demonstrating some of the different parameters effects on the model performance.     

Expected repair cost under doubly stochastic damage processes

There are a number of instances where the problems of non-stationarity, Poisson compounding and double stochasticity arise. In the theory of space-charge limited shot-noise, the number of beats that occur in a given interval of time obey a doubly stochastic process since the Poisson's parameter λ changes randomly due to individual beats. This paper puts forward a doubly stochastic non-stationary compound Poisson process as a model describing damage sustained by military equipment, solar collectors, … etc., due to hailstones. The expected repair cost due to such damage is formulated.     

Design of digital filters for advanced telecommunications ASIC'susing a special-purpose silicon compiler

Complex DSP (digital signal processor) ASICs (application-specific integrated circuits) typically feature high-quality filters implemented as dedicated blocks. FIDYS (filter 1di synthesis system) is a new VLSI recursive filter compiler, specifically designed to meet those needs. It is fully integrated from behavioral frequency template specifications down to layout. It comprises a specific approximation and synthesis procedure, the generation of a systolic architecture with parameterized pipelining based on dedicated bit-serial operators, and final generation of a densely packed layout based on a minimal dedicated set of 1-μm CMOS basic cells. A lossless discrete integrator ladder filter structure is used. It features an outstanding low sensitivity and a high degree of modularity and regularity that directly result in streamlined hardware and an efficient placement with minimal routing overhead. Examples of representative applications for telecommunications circuits are presented