Optics Commons^™

Comparing Experts And Novices In Solving Electrical Circuit Problems With The Help Of Eye-Tracking, David Rosengrant, Colin Thomson, Taha Mzoughi

David Rosengrant

In order to help introductory physics students understand and learn to solve problems with circuits, we must first understand how they differ from experts. This preliminary study focuses on problem-solving dealing with electrical circuits. We investigate difficulties novices have with circuits and compare their work with those of experts. We incorporate the use of an eye-tracker to investigate any possible differences or similarities on how experts and novices solve electrical circuit problems. Our results show similarities in gaze patterns among all subjects on the components of the circuit. We further found that experts would look back at the circuit while …

Prioritizing Investment In Residential Energy Efficiency And Renewable Energy: A Case Study For The U.S. Midwest, Robert J. Brecha, Austin Mitchell, Kevin P. Hallinan, J. Kelly Kissock

J. Kissock

Residential building energy use is an important contributor to greenhouse gas emissions and in the United States represents about 20% of total energy consumption. A number of previous macro-scale studies of residential energy consumption and energy-efficiency improvements are mainly concerned with national or international aggregate potential savings. In this paper we look into the details of how a collection of specific homes in one region might reduce energy consumption and carbon emissions, with particular attention given to some practical limits to what can be achieved by upgrading the existing residential building stock. Using a simple model of residential, single-family home …

Prioritizing Investment In Residential Energy Efficiency And Renewable Energy: A Case Study For The U.S. Midwest, Robert J. Brecha, Austin Mitchell, Kevin P. Hallinan, J. Kelly Kissock

Kevin Hallinan

Residential building energy use is an important contributor to greenhouse gas emissions and in the United States represents about 20% of total energy consumption. A number of previous macro-scale studies of residential energy consumption and energy-efficiency improvements are mainly concerned with national or international aggregate potential savings. In this paper we look into the details of how a collection of specific homes in one region might reduce energy consumption and carbon emissions, with particular attention given to some practical limits to what can be achieved by upgrading the existing residential building stock. Using a simple model of residential, single-family home …

Bose-Einstein Condensation Of Potassium Atoms By Sympathetic Cooling, Giovanni Modugno, Gabriele Ferrari, Giacomo Roati, Robert Brecha, A. Simoni, Massimo Inguscio

Robert J. Brecha

We report on the Bose-Einstein condensation of potassium atoms, whereby quantum degeneracy is achieved by sympathetic cooling with evaporatively cooled rubidium. Because of the rapid thermalization of the two different atoms, the efficiency of the cooling process is high. The ability to achieve condensation by sympathetic cooling with a different species may provide a route to the production of degenerate systems with a larger choice of components.

Collapse Of A Degenerate Fermi Gas, Giovanni Modugno, Giacomo Roati, Francesco Riboli, Francesca Ferlaino, Robert Brecha, Massimo Inguscio

Robert J. Brecha

A degenerate gas of identical fermions is brought to collapse by the interaction with a Bose-Einstein condensate. We used an atomic mixture of fermionic potassium-40 and bosonic rubidium-87, in which the strong interspecies attraction leads to an instability above a critical number of particles. The observed phenomenon suggests a direction for manipulating fermion-fermion interactions on the route to superfluidity.

Cost Optimization With Solar And Conventional Energy Production, Energy Storage, And Real Time Pricing, Ata Raziei, Kevin Hallinan, Robert Brecha

Robert J. Brecha

Research is presented that investigates the potential for solar power generation with battery energy storage for reducing the effective cost of energy delivered to residential customers if real time pricing is present. A linear optimization approach is developed based upon a two-step process. In step one, given a specified solar array area and battery capacity, the optimal means to meet loads based upon grid power, solar power, and/or battery power is determined. This analysis considers an expected lifespan of the solar panel. With these results established, in the next step, the capital costs for the solar arrays and batteries are …

Dipolar Oscillations In A Quantum Degenerate Fermi–Bose Atomic Mixture, Francesca Ferlaino, Robert Brecha, Peter Hannaford, Francesco Riboli, Giacomo Roati, Giovanni Modugno, Massimo Inguscio

Robert J. Brecha

We study the dynamics of coupled dipolar oscillations in a Fermi–Bose mixture of 40K and 87Rb atoms. This low-energy collective mode is strongly affected by the interspecies interactions. Measurements are performed in the classical and quantum degenerate regimes and reveal the crucial role of the statistical properties of the mixture. At the onset of quantum degeneracy, we investigate the role of Pauli blocking and superfluidity for K and Rb atoms, respectively, resulting in a change in the collisional interactions.

The Carbon Rent Economics Of Climate Policy, Matthias Kalkuhl, Robert Brecha

Robert J. Brecha

By reducing the demand for fossil fuels, climate policy can reduce scarcity rents for fossil resource owners. As mitigation policies ultimately aim to limit emissions, a new scarcity for “space” in the atmosphere to deposit emissions is created. The associated scarcity rent, or climate rent (that is, for example, directly visible in permit prices under an emission trading scheme) can be higher or lower than the original fossil resource rent. In this paper, we analyze analytically and numerically the impact of mitigation targets, resource availability, backstop costs, discount rates and demand parameters on fossil resource rents and the climate rent. …

Analyzing Major Challenges Of Wind And Solar Variability In Power Systems, Falko Ueckerdt, Robert Brecha, Gunnar Luderer

Robert J. Brecha

Ambitious policy targets together with current and projected high growth rates indicate that future power systems will likely show substantially increased generation from renewable energy sources. A large share will come from the variable renewable energy (VRE) sources wind and solar photovoltaics (PV); however, integrating wind and solar causes challenges for existing power systems. In this paper we analyze three major integration challenges related to the structural matching of demand with the supply of wind and solar power: low capacity credit, reduced utilization of dispatchable plants, and over-produced generation. Based on residual load duration curves we define corresponding challenge variables …

Global Fossil Energy Markets And Climate Change Mitigation: An Analysis With Remind, Nico Bauer, Ioanna Mouratiadou, Gunnar Luderer, Lavinia Baumstark, Robert Brecha, Ottmar Edenhofer, Elmar Kriegler

Robert J. Brecha

We analyze the dynamics of global fossil resource markets under different assumptions for the supply of fossil fuel resources, development pathways for energy demand, and climate policy settings. Resource markets, in particular the oil market, are characterized by a large discrepancy between costs of resource extraction and commodity prices on international markets. We explain this observation in terms of (a) the intertemporal scarcity rent, (b) regional price differentials arising from trade and transport costs, (c) heterogeneity and inertia in the extraction sector. These effects are captured by the REMIND model. We use the model to explore economic effects of changes …

Logistic Curves, Extraction Costs And Peak Oil, Robert Brecha

Robert J. Brecha

Debates about the possibility of a near-term maximum in world oil production have become increasingly prominent over the past decade, with the focus often being on the quantification of geologically available and technologically recoverable amounts of oil in the ground. Economically, the important parameter is not a physical limit to resources in the ground, but whether market price signals and costs of extraction will indicate the efficiency of extracting conventional or nonconventional resources as opposed to making substitutions over time for other fuels and technologies. We present a hybrid approach to the peak-oil question with two models in which the …

Economic And Environmental Impacts Of Community-Based Residential Building Energy Efficiency Investment, Jun-Ki Choi, Drew Morrison, Kevin Hallinan, Robert Brecha

Robert J. Brecha

A systematic framework for evaluating the local economic and environmental impacts of investment in building energy efficiency is developed. Historical residential building energy data, community-wide economic input-output data, and emission intensity data are utilized. The aim of this study is to show the comprehensive insights and connection among achieving variable target reductions for a residential building energy use, economic and environmental impacts. Central to this approach for the building energy reduction goal is the creation of individual energy models for each building based upon historical energy data and available building data. From these models, savings estimates and cost implications can …

Development Without Energy? Assessing Future Scenarios Of Energy Consumption In Developing Countries, Jan Steckel, Robert Brecha, Michael Jakob, Jessica Strefler, Gunnar Luderer

Robert J. Brecha

We analyze the relationship between economic development and energy consumption in the context of greenhouse gas mitigation. The main contribution of this work is to compare estimates of energy thresholds in the form of minimum energy requirements to reach high levels of development with output projections of per capita final energy supply from a group of integrated assessment models (IAMs). Scenarios project that reductions of carbon emissions in developing countries will be achieved not only by means of decreasing the carbon intensity, but also by making a significant break with the historically observed relationship between energy use and economic growth. …

Variable Renewable Energy In Modeling Climate Change Mitigation Scenarios, Falko Ueckerdt, Robert J. Brecha, Gunnar Luderer, Patrick Sullivan, Eva Schmid, Nico Bauer, Diana Böttger

Robert J. Brecha

This paper addresses the issue of how to account for short‐term temporal variability of renewable energy sources and power demand in long‐term climate change mitigation scenarios in energy‐economic models. An approach that captures in a stylized way the major challenges to the integration of variable renewable energy sources into power systems has been developed. As a first application this approach has been introduced to REMIND‐D, a hybrid energy‐economy model of Germany. An approximation of the residual load duration curve is implemented. The approximating function endogenously changes depending on the penetration and mix of variable renewable power. The approach can thus …

Establishing Building Recommissioning Priorities And Potential Energy Savings From Utility Energy Data, Kevin P. Hallinan, Philip Brodrick, Jessica Northridge, J. Kelly Kissock, Robert J. Brecha

Robert J. Brecha

An energy reduction program for commercial buildings is implemented for a SW Ohio natural gas utility. The aim of this study is to demonstrate that historical utility data for individual building customers, along with knowledge of pertinent building information (square footage, year built, number of floors, height of floors, wall construction type, and use type) available in county auditor databases, could be used to identify the best candidate buildings for recommissioning in terms of energy savings and simple payback. A study is completed for all natural gas customers of a utility in Montgomery and Clinton counties in Ohio. A total …

Cooling Atoms In An Optical Trap By Selective Parametric Excitation, Nicola Poli, Robert J. Brecha, Giacomo Roati, Giovanni Modugno

Robert J. Brecha

We demonstrate the possibility of energy-selective removal of cold atoms from a tight optical trap by means of parametric excitation of the trap vibrational modes. Taking advantage of the anharmonicity of the trap potential, we either selectively remove the most energetic trapped atoms or excite those at the bottom of the trap by tuning the parametric modulation frequency. This process, which had been previously identified as a possible source of heating, also appears to be a robust way for forcing evaporative cooling in anharmonic traps.

Economics Of Nuclear Power And Climate Change Mitigation Policies, Nico Bauer, Robert Brecha, Gunnar Luderer

Robert J. Brecha

The events of March 2011 at the nuclear power complex in Fukushima, Japan, raised questions about the safe operation of nuclear power plants, with early retirement of existing nuclear power plants being debated in the policy arena and considered by regulators. Also, the future of building new nuclear power plants is highly uncertain. Should nuclear power policies become more restrictive, one potential option for climate change mitigation will be less available. However, a systematic analysis of nuclear power policies, including early retirement, has been missing in the climate change mitigation literature. We apply an energy economy model framework to derive …

Two-Level Atom In An Optical Parametric Oscillator: Spectra Of Transmitted And Fluorescent Fields In The Weak Driving Field Limit, James P. Clemens, Perry R. Rice, Pranaw Kumar Rungta, Robert J. Brecha

Robert J. Brecha

We consider the interaction of a two-level atom inside an optical parametric oscillator. In the weak-driving-field limit, we essentially have an atom-cavity system driven by the occasional pair of correlated photons, or weakly squeezed light. We find that we may have holes, or dips, in the spectrum of the fluorescent and transmitted light. This occurs even in the strong-coupling limit when we find holes in the vacuum-Rabi doublet. Also, spectra with a subnatural linewidth may occur. These effects disappear for larger driving fields, unlike the spectral narrowing obtained in resonance fluorescence in a squeezed vacuum; here it is important that …

Renewable Energy In The Context Of Sustainable Development, Jayant Sathaye, Oswaldo Lucon, Atiq Rahman, John Christensen, Fatima Denton, Junichi Fujino, Garvin Heath, Monirul Mirza, Hugh Rudnick, August Schlaepfer, Andrey Shmakin, Gerhard Angerer, Christian Bauer, Morgan Bazilian, Robert J. Brecha, Peter Burgherr, Leon Clarke, Felix Creutzig, James Edmonds, Christian Hagelüken, Gerrit Hansen, Nathan Hultman, Michael Jakob, Susanne Kadner, Manfred Lenzen, Jordan Macknick, Eric Masanet, Yu Nagai, Anne Olhoff, Karen Olsen, Michael Pahle, Ari Rabl, Richard Richels, Joyashree Roy, Tormod Schei, Christoph Von Stechow, Jan Christoph Steckel, Ethan Warner, Tom Wilbanks, Yimin Zhang

Robert J. Brecha

Historically, economic development has been strongly correlated with increasing energy use and growth of greenhouse gas (GHG) emissions. Renewable energy (RE) can help decouple that correlation, contributing to sustainable development (SD). In addition, RE offers the opportunity to improve access to modern energy services for the poorest members of society, which is crucial for the achievement of any single of the eight Millennium Development Goals. Theoretical concepts of SD can provide useful frameworks to assess the interactions between SD and RE. SD addresses concerns about relationships between human society and nature. Traditionally, SD has been framed in the three-pillar model—Economy, …

Ten Reasons To Take Peak Oil Seriously, Robert Brecha

Robert J. Brecha

Forty years ago, the results of modeling, as presented in The Limits to Growth, reinvigorated a discussion about exponentially growing consumption of natural resources, ranging from metals to fossil fuels to atmospheric capacity, and how such consumption could not continue far into the future. Fifteen years earlier, M. King Hubbert had made the projection that petroleum production in the continental United States would likely reach a maximum around 1970, followed by a world production maximum a few decades later. The debate about “peak oil," as it has come to be called, is accompanied by some of the same vociferous denials, …

Properties Of Exchange Coupled All-Garnet Magneto-Optic Thin Film Multilayer Structures, Mohammad Nur-E-Alam, Mikhail Vasiliev, Viacheslav A. Kotov, Dmitry Balabanov, Ilya Akimov, Kamal Alameh

Mikhail Vasiliev

The effects of exchange coupling on magnetic switching properties of all-garnet multilayer thin film structures are investigated. All-garnet structures are fabricated by sandwiching a magneto-soft material of composition type Bi1.8Lu1.2Fe3.6Al1.4O12 or Bi3Fe5O12:Dy2O3 in between two magneto-hard garnet material layers of composition type Bi2Dy1Fe4Ga1O12 or Bi2Dy1Fe4Ga1O12:Bi2O3. The fabricated RF magnetron sputtered exchange-coupled all-garnet multilayers demonstrate a very attractive combination of magnetic properties, and are of interest for emerging applications in optical sensors and isolators, ultrafast nanophotonics and magneto-plasmonics. An unconventional type of magnetic hysteresis behavior not observed previously in magnetic garnet thin films is reported and discussed.

The Effect Of Copt Crystallinity And Grain Texturing On Properties Of Exchange-Coupled Fe/Copt Systems, H. Oguchi, A. Zambano, M. Yu, Jason Hattrick-Simpers, D. Banerjee, Y. Liu, Z. Wang, J. Liu, S. Lofland, D. Josell, I. Takeuchi

Jason R. Hattrick-Simpers

The effect of the crystallinity and the grain texturing of CoPt hard layers on exchange coupled Fe/CoPt soft/hard magnetic systems was studied using gradient thickness multilayer thin films. We have studied the hard layer structures by transmission electron microscopy and x-ray diffraction, and characterized the exchange coupling interaction through magnetization loops obtained by the magneto-optical Kerr effect measurement. We found that exchange coupling strongly depends on the crystalline characteristics of the CoPt hard layer. There is correlation between the mixture of different grain orientations of the CoPt hard layer and coupling efficiency. In particular, interlayer coupling is enhanced when there …

Rapid Structural Mapping Of Ternary Metallic Alloy Systems Using The Combinatorial Approach And Cluster Analysis, C. Long, Jason Hattrick-Simpers, M. Murakami, R. Srivastava, I. Takeuchi, V. Karen, X. Li

Jason R. Hattrick-Simpers

We are developing a procedure for the quick identification of structural phases in thin film composition spread experiments which map large fractions of compositional phase diagrams of ternary metallic alloy systems. An in-house scanning x-ray microdiffractometer is used to obtain x-ray spectra from 273 different compositions on a single composition spread library. A cluster analysissoftware is then used to sort the spectra into groups in order to rapidly discover the distribution of phases on the ternary diagram. The most representative pattern of each group is then compared to a database of known structures to identify known phases. Using this method, …

Note: A Simple Thermal Gradient Annealing Unit For The Treatment Of Thin Films, C. Metting, Johnathan Bunn, Ellen Underwood, Yihao Zhu, G. Koley, T. Crawford, Jason Hattrick-Simpers

Jason R. Hattrick-Simpers

A gradient annealing cell has been developed for the high-throughput study of thermalannealing effects on thin-film libraries in different environments. The inexpensive gradientannealing unit permits temperature gradients as large as 28 °C/mm and can accommodate samples ranging in length from 13 mm to 51 mm. The system was validated by investigating the effects of annealing temperature on the crystallinity, resistivity, and transparency of tin-doped indium oxide deposited on a glass substrate by magnetron sputtering. The unit developed in this work will permit the rapid optimization of materials properties such as crystallinity, homogeneity, and conductivity across a variety of applications.

Combinatorial Investigation Of Magnetostriction In Fe-Fa And Fe-Ga-Al, Jason R. Hattrick-Simpers, Dwight Hunter, Corneliu M. Craciunescu, Kyu Sung Jang, Makoto Murakami, James Cullen, Manfred Wuttig, Ichiro Takeuchi, Samuel E. Lofland, Leonid Bendersky, Noble Woo, Robert Bruce Vandover, Toshiya Takahashi, Yasubumi Furuya

Jason R. Hattrick-Simpers

A high-throughput high-sensitivity optical technique for measuringmagnetostriction of thin-film composition-spread samples has been developed. It determines the magnetostriction by measuring the induced deflection of micromachined cantilever unimorph samples. Magnetostrictionmeasurements have been performed on as-deposited Fe–Ga and Fe–Ga–Al thin-film composition spreads. The thin-film Fe–Ga spreads display a similar compositional variation of magnetostriction as bulk. A previously undiscovered peak in magnetostriction at low Ga content was also observed and attributed to a maximum in the magnetocrystalline anisotropy. Magnetostrictive mapping of the Fe–Ga–Al ternary system reveals the possibility of substituting up to 8at.%Al in Fe₇₀Ga₃₀ without significant degradation of magnetostriction.

Sensitive And Ultra-Fast Species Detection Using Pulsed Cavity Ringdown Spectroscopy, Et-Touhami Es-Sebbar

Dr. Et-touhami Es-sebbar

Pulsed cavity ringdown spectroscopy (CRDS) is used to develop a novel, ultra-fast, high-sensitivity diagnostic for measuring species concentrations in shock tube experiments. The diagnostic is demonstrated by monitoring trace concentrations of ethylene in the mid-IR region near 949.47 cm−1. Each ringdown measurement is completed in less than 1 μs and the time period between successive pulses is 10 μs. The high sensitivity diagnostic has a noise-equivalent detection limit of 1.08 x 10−5 cm−1 which enables detection of 15 ppm ethylene at fuel pyrolysis conditions (1845 K and 2 bar) and 294 ppb ethylene under ambient conditions (297 K and 1 …

Video Feature — Banned Books And The Stuart Rose Collection, Robert Brecha, Una Cadegan, John Inglis, Paul Morman

Robert J. Brecha

A faculty panel discussion in two sessions:

Session 1:
The Index: Una Cadegan (history) looks at the current scholarship on the Index of Forbidden Books.
Galileo: Robert Brecha (physics) highlights the banning of Galileo and observational science.

Session 2:
Thomas Aquinas: John Inglis (philosophy) speaks on the banning of Thomas Aquinas's Summa Theologica, the most important book in Catholic intellectual tradition.
Descartes and the Index of Forbidden Books: Paul Morman (history, Distinguished Service Professor) highlights the book by Descartes that he was not allowed to study while a student at UD in the 1960s.