Ronald J. Spiegel

Design and performance evaluation of a fuzzy logic based variable speed wind generation system

Artificial intelligence techniques, such as fuzzy logic, neural network and genetic algorithm are showing a lot of promise in the application of power electronic systems. The paper describes the control strategy development, design and experimental performance evaluation of a fuzzy logic based variable speed wind generation system that uses a cage type induction generator and double-sided PWM converters. The system can feed a utility grid maintaining unity power factor at all conditions, or can supply to an autonomous load. The fuzzy logic based control of the system helps to optimize the efficiency and enhance the performance. A complete 3.5 kW generation system has been developed, designed and thoroughly evaluated by laboratory tests in order to validate the predicted performance improvements. The system gives excellent performance, and can easily be translated to a larger size in the field.

Resonance Absorption of Microwaves by the Human Skull

Resonance absorption of microwaves by the human skull is examined by making computerized calculations of theoretical models of the skull. The calculated relative absorption versus frequency is plotted and compared for homogeneous and inhomogeneous skull models. At a frequency of maximum power absorption, the spatial distribution of intracranial field intensity (based upon the theoretical model) is also calculated and plotted.

RF Energy Deposition in a Heterogeneous Model of Man: Near-Field Exposures

The electric field strength was measured in a full-scale heterogeneous model of man exposed in the near field of resonant dipoles. The model was comprised of skull, spinal cord, rib cage, all other major bones, brain, lung, and muscle tissue. Electrical properties of these simulated tissues were the same as respective live tissue properties at test frequencies of 160, 350, and 915 MHz. The rates of energy absorption were calculated on the basis of the measured field strengths and tissue conductivities. Patterns of the energy deposition are compared for two orientations of the antennas with respect to the body. Also the results for the heterogeneous model are compared to data for homogeneous model having average tissue electrical properties.

Fuel cell operation on landfill gas at Penrose Power Station

This demonstration test successfully demonstrated the operation of a commercial phosphoric acid fuel cell (FC) on landfill gas (LG) at the Penrose Power Station in Sun Valley, CA. Demonstration output included operation up to 137kW; 37.1% efficiency at 120kW; exceptionally low secondary emissions (dry gas, 15% O2) of 0.77ppmV CO, 0.12ppmV NOx, and undetectable SO2; no forced outages with an adjusted availability of 98.5%; and a total of 707h of operation on LG. The LG pretreatment unit (GPU) operated for a total of 2297h, including the 707h with the FC, and documented total sulfur and halide removal to much lower than the specified <3ppmV for the FC. The GPU flare safely disposed of the removed LG contaminants by achieving destruction efficiencies greater than 99%.

Numerical Determination of Induced Currents in Humans and Baboons Exposed to 60-Hz Electric Fields

In order to extropolate 60-Hz electric-field effects on experimental animals (baboons) in terms of equivalent effects on man, scaling relations for the induced current densities have been developed by utilizing advanced computer-modeling techniques. Humans and baboons were modeled by a large number of small cubical blocks that were arranged to obtain the best possible fit to the contour of the object. Internal current densities for the models were calculated by the solution of an integral equation for the induced polarization at the center of each block.

Technical assessment of fuel cell operation on landfill gas at the Groton, CT, landfill

This paper summarizes the results of a seminal assessment conducted on a fuel cell technology that generates electrical power from landfill waste gas. This assessment at Groton, Connecticut was the second such project conducted by the Environmental Protection Agency (EPA), the first being conducted at the Penrose Power Station near Los Angeles, California. The main objective was to demonstrate the suitability of the landfill gas energy conversion equipment at Groton with different conditions and gas compositions than at Penrose. The operation of the landfill gas cleanup system removed contaminants from the gas stream with essentially the same efficacy as at Penrose, even though the quantity and kinds of contaminants were somewhat different. The fuel cell power plant’s maximum output power improved from 137 kW at Penrose to 165 kW at Groton, due to a 31% increase in the heating value of the Groton landfill gas.

Test results for fuel-cell operation on landfill gas

Test results from a demonstration of fuel-cell (FC) energy recovery and control of landfill gas emissions are presented. The project addressed two major issues: (i) the design, construction, and testing of a landfill-gas cleanup system; and (ii) a field test of a commercial phosphoric acid fuel cell (PAFC) power plant operating on the cleaned landfill gas. A summary of test results on the cleanup system and FC operational data are given. These results may encourage the use of landfill gas in FCs, one of the cleanest energy-conversion technologies available.

Technical assessment of fuel cell operation on anaerobic digester gas at the Yonkers, NY, wastewater treatment plant

This paper summarizes the results of a 2-year field test to assess the performance of a specially modified commercial phosphoric acid 200-kW fuel cell power plant to recover energy from anaerobic digester gas (ADG) which has been cleansed of contaminants (sulfur and halide compounds) using a patented gas pretreatment unit (GPU). Specific project goals include characterization of the fuel cell power plant emissions and verification of the GPU performance for removing sulfur contaminants. To remove halide contaminants from the ADG, a halide guard, consisting of a vessel with a metal oxide supported on alumina, was incorporated into the fuel cell reactant supply. This first-of-a-kind demonstration was conducted at the Yonkers, NY, wastewater treatment plant, a sewage processing facility owned and operated by Westchester County. Results have demonstrated that the ADG fuel cell power plant can produce electrical output levels close to full power (200 kW) with negligible air emissions of CO, NO(x), and SO(2). The GPU removed virtually 100% of H(2)S and 88% of organic sulfur, bringing the overall sulfur removal efficiency of the GPU to over 99%. The halide guard removed up to 96% of the halides exiting the GPU.

A Method for Calculating Electric And Magnetic Fields in TEM Cells at ELF

A method is presented whereby the electric and magnetic field distributions within rectangular-strip transmission lines (TEM cells) can be calculated. Quasi-static approximations are employed, thereby restricting the validity of the results to operational frequencies well below the cell cutoff frequency. The method is illustrated by calculating the fields within an existing structure used in biological experimentation. Where possible, calculations are compared with measured data.

Emissions reduction data for grid-connected photovoltaic power systems

This study measured the pollutant emission reduction potential of 29 photovoltaic (PV) systems installed on residential and commercial building rooftops across the US from 1993 through 1997. The US Environmental Protection Agency (EPA) and 21 electric power companies sponsored the project. This article presents results of analyses of each PV system’s ability to offset electric utility power plant emissions of sulfur dioxide (SO2), nitrogen oxides (NOx), and carbon dioxide (CO2). Each PV system’s performance was monitored and compared with hour-by-hour operating characteristics of the participating electric utilities in order to determine pollution offsets. The monthly mean and standard deviation offset are given for each pollutant, along with the coefficient of variation.