Keith E. Holbert

Embedding remote experimentation in power engineering education

Engineering education by its nature is a costly program in university environments. Perhaps the most costly component is the laboratory facility, usually consisting of specialized equipment. Effective instruction of some topics in power engineering education requires experience with actual equipment, rather than small-scale replicas or simulation. In this paper, a new laboratory approach is described, as implemented in a virtual, Internet-based, experimentation platform. This virtual laboratory (VLab) utilizes real equipment distributed among multiple universities from which remotely located students can perform experiments. The software solution is a multiuser, client-server architecture developed in the LabVIEW environment. Implementation details including video, chat, archiving, and the hardware and software platforms are presented in the paper. An example presented herein is the study of current and voltage waveforms while controlling relays and low-voltage contactors. The applications have been tested with student teams enrolled in the electrical engineering department of Politehnica University of Bucharest and the power engineering program at Arizona State University.

Enhanced TID Susceptibility in Sub-100 nm Bulk CMOS I/O Transistors and Circuits

This paper evaluates the radiation responses of 2.5 V I/O transistors and regular-threshold MOSFETs from a 90 nm commercial bulk CMOS technology. The data obtained from Co ionizing radiation experiments indicate enhanced TID susceptibility in I/O devices and circuits, which is attributed to the p-type body doping. A quantitative model is used to analyze the effects of doping and oxide trapped charge buildup along the sidewall of the shallow trench isolation oxide. These effects are captured in the general electrostatic equation for surface potential, which can be correlated to off-state leakage current. Device simulations are used in concert with experimental measurements and the analytical model to provide physical insight into the radiation response of each device type.

Mechanisms of Enhanced Radiation-Induced Degradation Due to Excess Molecular Hydrogen in Bipolar Oxides

Bipolar junction test structures packaged in hermetically sealed packages with excess molecular hydrogen (H2) showed enhanced degradation after radiation exposure. Using chemical kinetics, we propose a model that quantitatively establishes the relationship between excess H2 and radiation-induced interface trap formation. Using environments with different molecular hydrogen concentrations, radiation experiments were performed and the experimental data showed excellent agreement with the proposed model. The results, both experimentally and theoretically, showed increased radiation induced degradation with H2 concentration, and device degradation saturate at both high and low ends of H2 concentrations.

The Effects of Hydrogen on the Enhanced Low Dose Rate Sensitivity (ELDRS) of Bipolar Linear Circuits

It is experimentally demonstrated with test transistors and circuits that hydrogen is correlated with enhanced low dose rate sensitivity (ELDRS) in bipolar linear circuits. These experiments show that the amount of hydrogen determines the total dose response versus dose rate, both the saturation at low dose rate and the transition dose rate between the high and low dose rate responses. The experimental results are supported with modeling calculations using REOS (radiation effects in oxides and semiconductors).

Use of Satellite Technologies for Power System Measurements, Command, and Control

This paper analyzes the use of wide-area measurement technologies including satellite-based methods for the command and control of power systems. The methods studied include the global positioning system (GPS) and low earth orbit satellites (LEOS). Satellite technologies have been used in a variety of applications requiring precise timing between geographically diverse locations. The deregulation of the electric power industry is placing increased demands on power transmission system utilization. Because deregulated power systems utilize long-distance high-power exchanges, satellite-based communication systems are useful in control of geographically large interconnected power systems. In this paper, the satellite-based measurements and commands are introduced for wide-area control. With the support of wide-area signals, a multiagent supervisory-level power system stabilizer is proposed here as a potential wide-area control structure. Increased loading of transmission facilities is an impetus for accurate dynamic thermal overhead electrical conductor ratings. The application of satellite-based measurement for improving the dynamic thermal rating of overhead transmission circuits is suggested.

Strategies, Challenges and Prospects for Active Learning in the Computer-Based Classroom

The introduction of computer-equipped classrooms into engineering education has brought with it a host of opportunities and issues. Herein, some of the challenges and successes for creating an environment for active learning within computer-based classrooms are described. The particular teaching approach developed for undergraduate electrical engineering courses is presented. Longitudinal assessment data regarding in-class utilization of computers in the context of achieving program and course learning outcomes are shared.

Prospects for dynamic transmission circuit ratings

In this paper, the basic concepts of dynamic thermal ratings of overhead transmission conductors are discussed. The sensitivity of these ratings with ambient conditions is evaluated. Innovative concepts in the measurement of overhead sag are given and correlated with dynamic rating of overhead transmission conductors. Dynamic transmission line thermal ratings take on increased importance in the deregulated electric power industry, since transmission capacity is sold as a deregulated commodity. Also, the electric utilities are under pressure to utilize all their transmission resources to the fullest.

Optimizing Radiation Hard by Design SRAM Cells

Various radiation hardened by design SRAM cells are explored for their size, electrical performance, and total ionizing dose (TID) immunity. TID experiments using Co-60 testing on 130- and 90-nm transistors and SRAM arrays show that SRAM cells using two-edge transistors, NMOS access transistors, and NMOS reverse-body-bias effectively mitigate TID in both generations. This work experimentally demonstrates that commercial foundry (optimally sized) SRAM cells can be used in radiation hardening by design if NMOS reverse-body bias is used for TID mitigation.

Total ionizing dose effect of γ-ray radiation on the switching characteristics and filament stability of HfOx resistive random access memory

The total ionizing dose (TID) effect of gamma-ray (γ-ray) irradiation on HfOx based resistive random access memory was investigated by electrical and material characterizations. The memory states can sustain TID level ∼5.2 Mrad (HfO2) without significant change in the functionality or the switching characteristics under pulse cycling. However, the stability of the filament is weakened after irradiation as memory states are more vulnerable to flipping under the electrical stress. X-ray photoelectron spectroscopy was performed to ascertain the physical mechanism of the stability degradation, which is attributed to the Hf-O bond breaking by the high-energy γ-ray exposure.

Total-Ionizing-Dose Effects on the Resistance Switching Characteristics of Chalcogenide Programmable Metallization Cells

Programmable metallization cells (PMCs) are emerging ReRAM devices exhibiting resistance switching due to cation transport in a solid-state electrolyte and redox reactions at the electrodes. Their non-volatility and low power requirements have led to increased interest in their development for non-volatile memory applications. Investigation of the total dose response of PMCs will contribute to our understanding of radiation induced effects in these novel memory devices as well as assess their suitability for use in ionizing radiation environments. This work investigates the impact of total ionizing dose on the switching characteristic of silver doped Ge30Se70 PMC memory devices. The results obtained show that the resistance switching characteristic of these cells which use a solid state electrolyte based on Ge30Se70 is not affected by a total dose exposure of up to 10 Mrad( Ge30Se70).