An experimental investigation of high amplitude panel flutter

Aluminum panel flutter tests at supersonic Mach number

A method for predicting the panel flutter fatigue life of Saturn 5 panels

Development of method for predicting fatigue life of panels under flutter conditions with application to Saturn 5 launch vehicle structure

Storage requirement definition study

A dish Stirling solar receiver (DSSR) and a heat pipe solar receiver with TES (HPSR) for a 25 kWe dish Stirling solar power system are described. The thermal performance and cost effectiveness of each are analyzed minute by minute over the equivalent of one year of solar insolation. Existing designs of these two systems were used as a basis for the study; TES concepts for the DSSR and alternative TES concepts for the HPSR are presented. Parametric performance and cost studies were performed to determine the operating and cost characteristics of these systems. Data are reported for systems (1) without TES and with varying amounts of TES, (2) with and without a fossil fuel combustor, (3) with varying solar to fossil power input, and (4) with different system control assumptions. The principal effects of TES duration, collector area, engine efficiency, and fuel cost sensitivity are indicated. Development needs for each of the systems are discussed and the need and nature of possible future TES solar modular experiments are presented and discussed

Intrinsic Metastabilities in the Charge Configuration of a Double Quantum Dot

We report a thermally activated metastability in a GaAs double quantum dot exhibiting real-time charge switching in diamond shaped regions of the charge stability diagram. Accidental charge traps and sensor back action are excluded as the origin of the switching. We present an extension of the canonical double dot theory based on an intrinsic, thermal electron exchange process through the reservoirs, giving excellent agreement with the experiment. The electron spin is randomized by the exchange process, thus facilitating fast, gate-controlled spin initialization. At the same time, this process sets an intrinsic upper limit to the spin relaxation time.Comment: 4 pages, 5 figures (color

A Conceptual Design Study on the Application of Liquid Metal Heat Transfer Technology to the Solar Thermal Power Plant

Alkali metal heat transfer technology was used in the development of conceptual designs for the transport and storage of sensible and latent heat thermal energy in distributed concentrator, solar Stirling power conversion systems at a power level of 15 kWe per unit. Both liquid metal pumped loop and heat pipe thermal transport were considered; system configurations included: (1) an integrated, focal mounted sodium heat pipe solar receiver (HPSR) with latent heat thermal energy storage; (2) a liquid sodium pumped loop with the latent heat storage, Stirling engine-generator, pump and valves located on the back side of the concentrator; and (3) similar pumped loops serving several concentrators with more centralized power conversion and storage. The focus mounted HPSR was most efficient, lightest and lowest in estimated cost. Design confirmation testing indicated satisfactory performance at all angles of inclination of the primary heat pipes to be used in the solar receiver

The effect of non-native earthworms on northern Michigan soils.

General Ecology - spring termEarthworms are a non-native species in northern Michigan and their impact on soil structure and ecosystem dynamics is still poorly understood. Alterations in the proportions of nitrogen and carbon in the soil affect primary production, which in turn has consequences for higher trophic levels. Our research investigated the effect of non-native earthworms on carbon and nitrogen in soils of northern Michigan by conducting one manipulative experiment in two soil types and one observational experiment. Our results showed that the total nitrogen and carbon in anecic earthworm burrows was positively correlated with the total values in non-burrows. Also, the earthworms significantly decreased carbon levels in sandy outwash plain soil rather than nutrient rich moraine soil and had negligible effects on nitrogen in both soils. Non-native earthworms catalyze the release of carbon into the atmosphere in outwash plains, therefore, negatively affecting the forest ecosystems. Concurrent with leading research, non-native earthworms stand to be invasive species.http://deepblue.lib.umich.edu/bitstream/2027.42/89444/1/Rozek_Zimmerman_Basham_2011.pd

GaAs Quantum Dot Thermometry Using Direct Transport and Charge Sensing

We present measurements of the electron temperature using gate defined quantum dots formed in a GaAs 2D electron gas in both direct transport and charge sensing mode. Decent agreement with the refrigerator temperature was observed over a broad range of temperatures down to 10 mK. Upon cooling nuclear demagnetization stages integrated into the sample wires below 1 mK, the device electron temperature saturates, remaining close to 10 mK. The extreme sensitivity of the thermometer to its environment as well as electronic noise complicates temperature measurements but could potentially provide further insight into the device characteristics. We discuss thermal coupling mechanisms, address possible reasons for the temperature saturation and delineate the prospects of further reducing the device electron temperature.Comment: 8 pages, 3 (color) figure

Self-Regulation in a Web-Based Course: A Case Study

Little is known about how successful students in Web-based courses self-regulate their learning. This descriptive case study used a social cognitive model of self-regulated learning (SRL) to investigate how six graduate students used and adapted traditional SRL strategies to complete tasks and cope with challenges in a Web-based technology course; it also explored motivational and environmental influences on strategy use. Primary data sources were three transcribed interviews with each of the students over the course of the semester, a transcribed interview with the course instructor, and the students’ reflective journals. Archived course documents, including transcripts of threaded discussions and student Web pages, were secondary data sources. Content analysis of the data indicated that these students used many traditional SRL strategies, but they also adapted planning, organization, environmental structuring, help seeking, monitoring, record keeping, and self-reflection strategies in ways that were unique to the Web-based learning environment. The data also suggested that important motivational influences on SRL strategy use—self-efficacy, goal orientation, interest, and attributions—were shaped largely by student successes in managing the technical and social environment of the course. Important environmental influences on SRL strategy use included instructor support, peer support, and course design. Implications for online course instructors and designers, and suggestions for future research are offered

Adaptive Signatures in Thermal Performance of the Temperate Coral Astrangia poculata

Variation in environmental characteristics and divergent selection pressures can drive adaptive differentiation across a species\u27 range. Astrangia poculata is a temperate scleractinian coral that provides unique opportunities to understand the roles of phenotypic plasticity and evolutionary adaptation in coral physiological tolerance limits. A. poculata inhabits hard bottom ecosystems from the northwestern Atlantic to the Gulf of Mexico and withstands an annual temperature range up to 20° C. Additionally, A. poculata is facultatively symbiotic and co-occurs in both symbiotic ( brown ) and aposymbiotic ( white ) states. Here, brown and white A. poculata were collected from Virginia (VA) and Rhode Island (RI), USA and exposed to heat (18-32° C) and cold (18-6° C) temperatures during which respiration (R) of the coral host along with photosynthesis (P) and photochemical efficiency (Fv /Fm) of Breviolum psygmophilum photosymbionts were measured. Thermal performance curves (TPCs) of respiration revealed a pattern of countergradient variation with RI corals exhibiting higher respiration rates overall, and specifically at 6, 15, 18, 22, and 26°C. Additionally, thermal optimum (Topt) analyses show a 3.8° C (brown) and 6.9° C (white) higher Topt in the VA population, corresponding to the warmer in situ thermal environment in VA. In contrast to respiration, no origin effect was detected in photosynthesis rates or Fv/Fm, suggesting a possible host-only signature of adaptation. This study is the first to consider A. poculata\u27s response to both heat and cold stress across symbiotic states and geography and provides insight into the potential evolutionary mechanisms behind the success of this species along the East Coast of the US

Feasibility study for a Scanning Celestial Attitude Determination System /SCADS/ for three axis attitude determination at a Command and Data Acquisition /CDA/ station Final report

Scanning Celestial Attitude Determination System /SCADS/ for three axis attitude determination at Command and Data Acquisition /CDA/ statio