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Sample records for achieve high thermal

  1. Achieving high power efficiency and low roll-off OLEDs based on energy transfer from thermally activated delayed excitons to fluorescent dopants.

    PubMed

    Wang, Shipan; Zhang, Yuewei; Chen, Weiping; Wei, Jinbei; Liu, Yu; Wang, Yue

    2015-08-01

    Achieving high power efficiencies at high-brightness levels is still an important issue for organic light-emitting diodes (OLEDs) based on the thermally activated delayed fluorescence (TADF) mechanism. Herein, enhanced electroluminescence efficiencies were achieved in fluorescent OLEDs using a TADF molecule, (4s,6s)-2,4,5,6-tetra(9H-carbazol-9-yl)isophthalonitrile (4CzIPN), as a host and quinacridone derivatives (QA) as fluorescent dopants. PMID:26120606

  2. A method to achieve comparable thermal states of car brakes during braking on the road and on a high-speed roll-stand

    NASA Astrophysics Data System (ADS)

    Wolff, Andrzej

    2010-01-01

    The temperature of a brake friction surface influences significantly the braking effectiveness. The paper describes a heat transfer process in car brakes. Using a developed program of finite element method, the temperature distributions in brake rotors (disc and drum brake) of a light truck have been calculated. As a preliminary consistency criterion of the brake thermal state in road and roll-stand braking conditions, a balance of the energy cumulated in the brake rotor has been taken into account. As the most reliable consistency criterion an equality of average temperatures of the friction surface has been assumed. The presented method allows to achieve on a roll-stand the analogical thermal states of automotive brakes, which are observed during braking in road conditions. Basing on this method, it is possible to calculate the braking time and force for a high-speed roll-stand. In contrast to the previous papers of the author, new calculation results have been presented.

  3. High temperature solar thermal technology

    NASA Technical Reports Server (NTRS)

    Leibowitz, L. P.; Hanseth, E. J.; Peelgren, M. L.

    1980-01-01

    Some advanced technology concepts under development for high-temperature solar thermal energy systems to achieve significant energy cost reductions and performance gains and thus promote the application of solar thermal power technology are presented. Consideration is given to the objectives, current efforts and recent test and analysis results in the development of high-temperature (950-1650 C) ceramic receivers, thermal storage module checker stoves, and the use of reversible chemical reactions to transport collected solar energy. It is pointed out that the analysis and testing of such components will accelerate the commercial deployment of solar energy.

  4. Mathematics Achievement in High- and Low-Achieving Secondary Schools

    ERIC Educational Resources Information Center

    Mohammadpour, Ebrahim; Shekarchizadeh, Ahmadreza

    2015-01-01

    This paper identifies the amount of variance in mathematics achievement in high- and low-achieving schools that can be explained by school-level factors, while controlling for student-level factors. The data were obtained from 2679 Iranian eighth graders who participated in the 2007 Trends in International Mathematics and Science Study. Of the…

  5. Highly directional thermal emitter

    DOEpatents

    Ribaudo, Troy; Shaner, Eric A; Davids, Paul; Peters, David W

    2015-03-24

    A highly directional thermal emitter device comprises a two-dimensional periodic array of heavily doped semiconductor structures on a surface of a substrate. The array provides a highly directional thermal emission at a peak wavelength between 3 and 15 microns when the array is heated. For example, highly doped silicon (HDSi) with a plasma frequency in the mid-wave infrared was used to fabricate nearly perfect absorbing two-dimensional gratings structures that function as highly directional thermal radiators. The absorption and emission characteristics of the HDSi devices possessed a high degree of angular dependence for infrared absorption in the 10-12 micron range, while maintaining high reflectivity of solar radiation (.about.64%) at large incidence angles.

  6. Highly Thermal Conductive Nanocomposites

    NASA Technical Reports Server (NTRS)

    Sun, Ya-Ping (Inventor); Connell, John W. (Inventor); Veca, Lucia Monica (Inventor)

    2015-01-01

    Disclosed are methods for forming carbon-based fillers as may be utilized in forming highly thermal conductive nanocomposite materials. Formation methods include treatment of an expanded graphite with an alcohol/water mixture followed by further exfoliation of the graphite to form extremely thin carbon nanosheets that are on the order of between about 2 and about 10 nanometers in thickness. Disclosed carbon nanosheets can be functionalized and/or can be incorporated in nanocomposites with extremely high thermal conductivities. Disclosed methods and materials can prove highly valuable in many technological applications including, for instance, in formation of heat management materials for protective clothing and as may be useful in space exploration or in others that require efficient yet light-weight and flexible thermal management solutions.

  7. Self Regulated Learning of High Achievers

    ERIC Educational Resources Information Center

    Rathod, Ami

    2010-01-01

    The study was conducted on high achievers of Senior Secondary school. Main objectives were to identify the self regulated learners among the high achievers, to find out dominant components and characteristics operative in self regulated learners and to compare self regulated learning of learners with respect to their subject (science and non…

  8. The Constraints of Poverty on High Achievement

    ERIC Educational Resources Information Center

    Burney, Virginia H.; Beilke, Jayne R.

    2008-01-01

    Research studies on school success often focus on the impact of discrete elements such as race, culture, ethnicity, gender, language, or school location on high achievement. The condition of poverty, however, may be the most important of all student differences in relation to high achievement; although not all schools have racial diversity, nearly…

  9. On the thermalization achieved in the reactions involving superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Bansal, Rajni

    2016-05-01

    In the present study, we aim to explore the role of Coulomb potential on the thermalization achieved in the reactions involving superheavy nuclei. Particularly, we shall study the degree of the equilibrium attained in a reaction by the 3D density plots, anisotropy ratio as well as by the rapidity distribution of the nucleons. Our study reveals that the degree of the equilibrium attained in the central reactions of the superheavy nuclei remains unaffected by the Coulomb potential.

  10. Catholic High Schools and Rural Academic Achievement.

    ERIC Educational Resources Information Center

    Sander, William

    1997-01-01

    A study of national longitudinal data examined effects of rural Catholic high schools on mathematics achievement, high school graduation rates, and the likelihood that high school graduates attend college. Findings indicate that rural Catholic high schools had a positive effect on mathematics test scores and no effect on graduation rates or rates…

  11. Achieving quasi-adiabatic thermal environment to maximize resolution power in very high-pressure liquid chromatography: Theory, models, and experiments.

    PubMed

    Gritti, Fabrice; Gilar, Martin; Jarrell, Joseph A

    2016-04-29

    A cylindrical vacuum chamber (inner diameter 5 cm) housing a narrow-bore 2.1 mm×100 mm column packed with 1.8 μm HSS-T3 fully porous particles was built in order to isolate thermally the chromatographic column from the external air environment. Consistent with statistical physics and the mean free path of air molecules, the experimental results show that natural air convection and conduction are fully eliminated for housing air pressures smaller than 10(-4) Torr. Heat radiation is minimized by wrapping up the column with low-emissivity aluminum-tape (emissivity coefficient ϵ=0.03 vs. 0.28 for polished stainless steel 316). Overall, the heat flux at the column wall is reduced by 96% with respect to standard still-air ovens. From a practical viewpoint, the efficiency of the column run at a flow rate of 0.6 mL/min at a constant 13,000 psi pressure drop (the viscous heat power is around 9 W/m) is improved by up to 35% irrespective of the analyte retention. Models of heat and mass transfer reveal that (1) the amplitude of the radial temperature gradient is significantly reduced from 0.30 to 0.01 K and (2) the observed improvement in resolution power stems from a more uniform distribution of the flow velocity across the column diameter. The eddy dispersion term in the van Deemter equation is reduced by 0.8±0.1 reduced plate height unit, a significant gain in column performance. PMID:27040511

  12. High Stakes Testing and Student Achievement.

    ERIC Educational Resources Information Center

    Ediger, Marlow

    The effects of high stakes testing may be critical in the lives of public school students and may have many consequences for schools and teachers. There are no easy answers in measuring student achievement and in holding teachers accountable for learner progress. High stakes testing also involves responsibilities on the part of the principal who…

  13. Student Perceptions of High-Achieving Classmates

    ERIC Educational Resources Information Center

    Händel, Marion; Vialle, Wilma; Ziegler, Albert

    2013-01-01

    The reported study investigated students' perceptions of their high-performing classmates in terms of intelligence, social skills, and conscientiousness in different school subjects. The school subjects for study were examined with regard to cognitive, physical, and gender-specific issues. The results show that high academic achievements in…

  14. High Achievers: 23rd Annual Survey. Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Northbrook, IL.

    This report presents data from an annual survey of high school student leaders and high achievers. It is noted that of the nearly 700,000 high achievers featured in this edition, 5,000 students were sent the survey and 2,092 questionnaires were completed. Subjects were high school juniors and seniors selected for recognition by their principals or…

  15. Achieving High Performance Perovskite Solar Cells

    NASA Astrophysics Data System (ADS)

    Yang, Yang

    2015-03-01

    Recently, metal halide perovskite based solar cell with the characteristics of rather low raw materials cost, great potential for simple process and scalable production, and extreme high power conversion efficiency (PCE), have been highlighted as one of the most competitive technologies for next generation thin film photovoltaic (PV). In UCLA, we have realized an efficient pathway to achieve high performance pervoskite solar cells, where the findings are beneficial to this unique materials/devices system. Our recent progress lies in perovskite film formation, defect passivation, transport materials design, interface engineering with respect to high performance solar cell, as well as the exploration of its applications beyond photovoltaics. These achievements include: 1) development of vapor assisted solution process (VASP) and moisture assisted solution process, which produces perovskite film with improved conformity, high crystallinity, reduced recombination rate, and the resulting high performance; 2) examination of the defects property of perovskite materials, and demonstration of a self-induced passivation approach to reduce carrier recombination; 3) interface engineering based on design of the carrier transport materials and the electrodes, in combination with high quality perovskite film, which delivers 15 ~ 20% PCEs; 4) a novel integration of bulk heterojunction to perovskite solar cell to achieve better light harvest; 5) fabrication of inverted solar cell device with high efficiency and flexibility and 6) exploration the application of perovskite materials to photodetector. Further development in film, device architecture, and interfaces will lead to continuous improved perovskite solar cells and other organic-inorganic hybrid optoelectronics.

  16. Reliability achievement in high technology space systems

    NASA Technical Reports Server (NTRS)

    Lindstrom, D. L.

    1981-01-01

    The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

  17. Academic achievement in high functioning autistic individuals.

    PubMed

    Minshew, N J; Goldstein, G; Taylor, H G; Siegel, D J

    1994-04-01

    Academic achievement levels in 54 high functioning (IQ > 70) autistic subjects were compared with those of 41 normal controls, who did not differ significantly in age, IQ, gender, race, or SES from the autistic subjects. The measures of academic achievement used included portions of the Detroit Tests of Learning Aptitude-2, the Woodcock Reading Mastery Test, and the Kaufman Test of Educational Achievement. Based on prior neuropsychological findings, it was hypothesized that autistic subjects would not differ from controls on subtests assessing mechanical and procedural skills, but would differ on subtests measuring comprehension and interpretive skills. As predicted, the autistic subjects performed significantly less well than controls on comprehension tasks, but not on mechanical reading, spelling, and computational tasks. This pattern is at variance with the typical academic profile of individuals with disabilities in reading or spelling, but shares some features with the nonverbal learning disabilities. PMID:8021313

  18. Achieving high performance on the Intel Paragon

    SciTech Connect

    Greenberg, D.S.; Maccabe, B.; Riesen, R.; Wheat, S.; Womble, D.

    1993-11-01

    When presented with a new supercomputer most users will first ask {open_quotes}How much faster will my applications run?{close_quotes} and then add a fearful {open_quotes}How much effort will it take me to convert to the new machine?{close_quotes} This paper describes some lessons learned at Sandia while asking these questions about the new 1800+ node Intel Paragon. The authors conclude that the operating system is crucial to both achieving high performance and allowing easy conversion from previous parallel implementations to a new machine. Using the Sandia/UNM Operating System (SUNMOS) they were able to port a LU factorization of dense matrices from the nCUBE2 to the Paragon and achieve 92% scaled speed-up on 1024 nodes. Thus on a 44,000 by 44,000 matrix which had required over 10 hours on the previous machine, they completed in less than 1/2 hour at a rate of over 40 GFLOPS. Two keys to achieving such high performance were the small size of SUNMOS (less than 256 kbytes) and the ability to send large messages with very low overhead.

  19. Attitudes and Opinions from the Nation's High Achieving Teens. 18th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Educational Communications, Inc., Lake Forest, IL.

    This document contains factsheets and news releases which cite findings from a national survey of 1,985 high achieving high school students. Factsheets describe the Who's Who Among American High School Students recognition and service program for high school students and explain the Who's Who survey. A summary report of this eighteenth annual…

  20. 22nd Annual Survey of High Achievers: Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Northbrook, IL.

    This study surveyed high school students (N=1,879) who were student leaders or high achievers in the spring of 1991 for the purpose of determining their attitudes. Students were members of the junior or senior high school class during the 1990-91 academic year and were selected for recognition by their principals or guidance counselors, other…

  1. 21st Annual Survey of High Achievers: Attitudes and Opinions from the Nation's High Achieving Teens.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey was conducted by Who's Who Among American High School Students during the spring of 1990, to determine the attitudes of student leaders in U.S. high schools. A survey of high achievers sent to 5,000 students was completed and returned by approximately 2,000 students. All students were members of the junior or senior class during the…

  2. Academic Attitudes of High Achieving and Low Achieving Academically Able Black Male Adolescents.

    ERIC Educational Resources Information Center

    Trotter, John Rhodes

    1981-01-01

    In order to identify the relationships between the attitudes and perceptions of peer pressure and the academic achievement of academically able male adolescents, this study compares the school attitudes of high achieving and low achieving Black male youth. (EF)

  3. Attitudes and Opinions from the Nation's High Achieving Teens: 26th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    A national survey of 3,351 high achieving high school students (junior and senior level) was conducted. All students had A or B averages. Topics covered include lifestyles, political beliefs, violence and entertainment, education, cheating, school violence, sexual violence and date rape, peer pressure, popularity, suicide, drugs and alcohol,…

  4. Attitudes and Opinions from the Nation's High Achieving Teens. 24th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey represents information compiled by the largest national survey of adolescent leaders and high achievers. Of the 5,000 students selected demographically from "Who's Who Among American High School Students," 1,957 responded. All students surveyed had "A" or "B" averages, and 98% planned on attending college. Questions were asked about…

  5. Thermal modeling of high efficiency AMTEC cells

    SciTech Connect

    Ivanenok, J.F. III; Sievers, R.K.; Crowley, C.J.

    1995-12-31

    Remotely condensed Alkali Metal Thermal to Electric Conversion (AMTEC) cells achieve high efficiency by thermally isolating the hot {beta} Alumina Solid Electrolyte (BASE) tube from the cold condensing region. In order to design high efficiency AMTEC cells the designer must understand the heat losses associated with the AMTEC process. The major parasitic heat losses are due to conduction and radiation, and significant coupling of the two mechanisms occurs. This paper describes an effort to characterize the thermal aspects of the model PL-6 AMTEC cell and apply this understanding to the design of a higher efficiency AMTEC cell, model PL-8. Two parallel analyses were used to model the thermal characteristics of PL-6. The first was a lumped node model using the classical electric circuit analogy and the second was a detailed finite-difference model. The lumped node model provides high speed and reasonable accuracy, and the detailed finite-difference model provides a more accurate, as well as visual, description of the cell temperature profiles. The results of the two methods are compared to the as-measured PL-6 data. PL-6 was the first cell to use a micromachined condenser to lower the radiation losses to the condenser, and it achieved a conversion efficiency of 15% (3 W output/20 W Input) at a temperature of 1050 K.

  6. High Thermal Conductivity Aligned Polyethylene-Graphene Nanocomposites

    NASA Astrophysics Data System (ADS)

    Garg, Jivtesh; Saeidijavash, Mortaza

    We investigate enhancement of thermal conductivity in polyethylene-graphene nanocomposites. The effect of alignment of both the polymer chains and the dispersed graphene flakes on thermal conductivity enhancement will be reported. In this work nanocomposites are prepared through microextrusion of polyethylene pellets and graphene nanopowder. Alignment is achieved through mechanical stretching of the nanocomposites. Thermal conductivity is measured using both Angstrom method and Laser flash. Variables involved in the study are the draw ratio and the weight percentage of graphene nanopowder. Results will shed light on the role of alignment of graphene flakes on enhancing thermal transport and provide new avenues to achieve ultra-high thermal conductivity in polymeric materials.

  7. High thermal conductivity of diamond

    NASA Technical Reports Server (NTRS)

    Stephan, Patrick M.

    1993-01-01

    The objectives of this educational exercise were to demonstrate the high rate of heat flow from a synthetic diamond coupon and to compare it to a commonly used thermal conductor, such as copper. The principles of heat transfer by conduction and convection may also be demonstrated. A list of equipment and supplies and the procedure for the experiment are presented.

  8. High Involvement Mothers of High Achieving Children: Potential Theoretical Explanations

    ERIC Educational Resources Information Center

    Hunsaker, Scott L.

    2013-01-01

    In American society, parents who have high aspirations for the achievements of their children are often viewed by others in a negative light. Various pejoratives such as "pushy parent," "helicopter parent," "stage mother," and "soccer mom" are used in the common vernacular to describe these parents. Multiple…

  9. Factors Implicated in High Mathematics Achievement

    ERIC Educational Resources Information Center

    Forgasz, Helen J.; Hill, Janelle C.

    2013-01-01

    The most recent Program for International Student Assessment (PISA) (2009) mathematical literacy results provide evidence that in Western English-speaking countries, including Australia, the gender gap in achievement appears to be widening in favour of males. In the study reported in this article, the aim was to explore the effects of gender,…

  10. High Ability Readers and the Achievement Gap

    ERIC Educational Resources Information Center

    Hunsaker, Scott L.; Parke, Cynthia J.; Bramble, Joan G.

    2004-01-01

    To close the achievement gap, the "No Child Left Behind" law calls for all students to make appropriate yearly progress. This presumably means that progress is being made by capable readers at the same time progress is being made by struggling readers. However, there appear to be unintended effects of "No Child Left Behind" that may impede the…

  11. High temperature solar thermal receiver

    NASA Technical Reports Server (NTRS)

    1979-01-01

    A design concept for a high temperature solar thermal receiver to operate at 3 atmospheres pressure and 2500 F outlet was developed. The performance and complexity of windowed matrix, tube-header, and extended surface receivers were evaluated. The windowed matrix receiver proved to offer substantial cost and performance benefits. An efficient and cost effective hardware design was evaluated for a receiver which can be readily interfaced to fuel and chemical processes or to heat engines for power generation.

  12. Achieving strategic surety for high consequence software

    SciTech Connect

    Pollock, G.M.

    1996-09-01

    A strategic surety roadmap for high consequence software systems under the High Integrity Software (HIS) Program at Sandia National Laboratories guides research in identifying methodologies to improve software surety. Selected research tracks within this roadmap are identified and described detailing current technology and outlining advancements to be pursued over the coming decade to reach HIS goals. The tracks discussed herein focus on Correctness by Design, and System Immunology{trademark}. Specific projects are discussed with greater detail given on projects involving Correct Specification via Visualization, Synthesis, & Analysis; Visualization of Abstract Objects; and Correct Implementation of Components.

  13. Norview High School: Leadership Fosters Achievment

    ERIC Educational Resources Information Center

    Principal Leadership, 2013

    2013-01-01

    Often little unsaid things demonstrate what is truly important in a school. When teachers have common planning time and all of the department chairs share a single space as they do at Norview High School in Norfolk, VA, the unmistakable message is that instructional collaboration and leadership are expected and valued. Norview, an urban,…

  14. Achieving High-Temperature Ferromagnetic Topological Insulator

    NASA Astrophysics Data System (ADS)

    Katmis, Ferhat

    Topological insulators (TIs) are insulating materials that display conducting surface states protected by time-reversal symmetry, wherein electron spins are locked to their momentum. This unique property opens new opportunities for creating next-generation electronic and spintronic devices, including TI-based quantum computation. Introducing ferromagnetic order into a TI system without compromising its distinctive quantum coherent features could lead to a realization of several predicted novel physical phenomena. In particular, achieving robust long-range magnetic order at the TI surface at specific locations without introducing spin scattering centers could open up new possibilities for devices. Here, we demonstrate topologically enhanced interface magnetism by coupling a ferromagnetic insulator (FMI) to a TI (Bi2Se3); this interfacial ferromagnetism persists up to room temperature, even though the FMI (EuS) is known to order ferromagnetically only at low temperatures (<17 K). The induced magnetism at the interface resulting from the large spin-orbit interaction and spin-momentum locking feature of the TI surface is found to greatly enhance the magnetic ordering (Curie) temperature of the TI/FMI bilayer system. Due to the short range nature of the ferromagnetic exchange interaction, the time-reversal symmetry is broken only near the surface of a TI, while leaving its bulk states unaffected. The topological magneto-electric response originating in such an engineered TI could allow for an efficient manipulation of the magnetization dynamics by an electric field, providing an energy efficient topological control mechanism for future spin-based technologies. Work supported by MIT MRSEC through the MRSEC Program of NSF under award number DMR-0819762, NSF Grant DMR-1207469, the ONR Grant N00014-13-1-0301, and the STC Center for Integrated Quantum Materials under NSF grant DMR-1231319.

  15. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect

    PI: James S. Tulenko; Co-PI: Ronald H. Baney,

    2007-10-14

    Uranium dioxide (UO2) is the most common fuel material in commercial nuclear power reactors. UO2 has the advantages of a high melting point, good high-temperature stability, good chemical compatibility with cladding and coolant, and resistance to radiation. The main disadvantage of UO2 is its low thermal conductivity. During a reactor’s operation, because the thermal conductivity of UO2 is very low, for example, about 2.8 W/m-K at 1000 oC [1], there is a large temperature gradient in the UO2 fuel pellet, causing a very high centerline temperature, and introducing thermal stresses, which lead to extensive fuel pellet cracking. These cracks will add to the release of fission product gases after high burnup. The high fuel operating temperature also increases the rate of fission gas release and the fuel pellet swelling caused by fission gases bubbles. The amount of fission gas release and fuel swelling limits the life time of UO2 fuel in reactor. In addition, the high centerline temperature and large temperature gradient in the fuel pellet, leading to a large amount of stored heat, increase the Zircaloy cladding temperature in a lost of coolant accident (LOCA). The rate of Zircaloy-water reaction becomes significant at the temperature above 1200 oC [2]. The ZrO2 layer generated on the surface of the Zircaloy cladding will affect the heat conduction, and will cause a Zircaloy cladding rupture. The objective of this research is to increase the thermal conductivity of UO2, while not affecting the neutronic property of UO2 significantly. The concept to accomplish this goal is to incorporate another material with high thermal conductivity into the UO2 pellet. Silicon carbide (SiC) is a good candidate, because the thermal conductivity of single crystal SiC is 60 times higher than that of UO2 at room temperature and 30 times higher at 800 oC [3]. Silicon carbide also has the properties of low thermal neutron absorption cross section, high melting point, good chemical

  16. Self-Concept and Achievement Motivation of High School Students

    ERIC Educational Resources Information Center

    Lawrence, A. S. Arul; Vimala, A.

    2013-01-01

    The present study "Self-concept and Achievement Motivation of High School Students" was investigated to find the relationship between Self-concept and Achievement Motivation of High School Students. Data for the study were collected using Self-concept Questionnaire developed by Raj Kumar Saraswath (1984) and Achievement Motive Test (ACMT)…

  17. High-Thermal-Conductivity Fabrics

    NASA Technical Reports Server (NTRS)

    Chibante, L. P. Felipe

    2012-01-01

    Heat management with common textiles such as nylon and spandex is hindered by the poor thermal conductivity from the skin surface to cooling surfaces. This innovation showed marked improvement in thermal conductivity of the individual fibers and tubing, as well as components assembled from them. The problem is centered on improving the heat removal of the liquid-cooled ventilation garments (LCVGs) used by astronauts. The current design uses an extensive network of water-cooling tubes that introduces bulkiness and discomfort, and increases fatigue. Range of motion and ease of movement are affected as well. The current technology is the same as developed during the Apollo program of the 1960s. Tubing material is hand-threaded through a spandex/nylon mesh layer, in a series of loops throughout the torso and limbs such that there is close, form-fitting contact with the user. Usually, there is a nylon liner layer to improve comfort. Circulating water is chilled by an external heat exchanger (sublimator). The purpose of this innovation is to produce new LCVG components with improved thermal conductivity. This was addressed using nanocomposite engineering incorporating high-thermalconductivity nanoscale fillers in the fabric and tubing components. Specifically, carbon nanotubes were added using normal processing methods such as thermoplastic melt mixing (compounding twin screw extruder) and downstream processing (fiber spinning, tubing extrusion). Fibers were produced as yarns and woven into fabric cloths. The application of isotropic nanofillers can be modeled using a modified Nielsen Model for conductive fillers in a matrix based on Einstein s viscosity model. This is a drop-in technology with no additional equipment needed. The loading is limited by the ability to maintain adequate dispersion. Undispersed materials will plug filtering screens in processing equipment. Generally, the viscosity increases were acceptable, and allowed the filled polymers to still be

  18. High thermal expansion, sealing glass

    DOEpatents

    Brow, R.K.; Kovacic, L.

    1993-11-16

    A glass composition is described for hermetically sealing to high thermal expansion materials such as aluminum alloys, stainless steels, copper, and copper/beryllium alloys, which includes between about 10 and about 25 mole percent Na[sub 2]O, between about 10 and about 25 mole percent K[sub 2]O, between about 5 and about 15 mole percent Al[sub 2]O[sub 3], between about 35 and about 50 mole percent P[sub 2]O[sub 5] and between about 5 and about 15 mole percent of one of PbO, BaO, and mixtures thereof. The composition, which may also include between 0 and about 5 mole percent Fe[sub 2]O[sub 3] and between 0 and about 10 mole percent B[sub 2]O[sub 3], has a thermal expansion coefficient in a range of between about 160 and 210[times]10[sup [minus]7]/C and a dissolution rate in a range of between about 2[times]10[sup [minus]7] and 2[times]10[sup [minus]9]g/cm[sup 2]-min. This composition is suitable to hermetically seal to metallic electrical components which will be subjected to humid environments over an extended period of time.

  19. High thermal expansion, sealing glass

    DOEpatents

    Brow, Richard K.; Kovacic, Larry

    1993-01-01

    A glass composition for hermetically sealing to high thermal expansion materials such as aluminum alloys, stainless steels, copper, and copper/beryllium alloys, which includes between about 10 and about 25 mole percent Na.sub.2 O, between about 10 and about 25 mole percent K.sub.2 O, between about 5 and about 15 mole percent Al.sub.2 O.sub.3, between about 35 and about 50 mole percent P.sub.2 O.sub.5 and between about 5 and about 15 mole percent of one of PbO, BaO, and mixtures thereof. The composition, which may also include between 0 and about 5 mole percent Fe.sub.2 O.sub.3 and between 0 and about 10 mole percent B.sub.2 O.sub.3, has a thermal expansion coefficient in a range of between about 160 and 210.times.10-7/.degree.C. and a dissolution rate in a range of between about 2.times.10.sup.- 7 and 2.times.10.sup.-9 g/cm.sup.2 -min. This composition is suitable to hermetically seal to metallic electrical components which will be subjected to humid environments over an extended period of time.

  20. Scientific Temper among Academically High and Low Achieving Adolescent Girls

    ERIC Educational Resources Information Center

    Kour, Sunmeet

    2015-01-01

    The present study was undertaken to compare the scientific temper of high and low achieving adolescent girl students. Random sampling technique was used to draw the sample from various high schools of District Srinagar. The sample for the present study consisted of 120 school going adolescent girls (60 high and 60 low achievers). Data was…

  1. High speed heterodyne infrared thermography applied to thermal diffusivity identification

    NASA Astrophysics Data System (ADS)

    Pradere, C.; Clerjaud, L.; Batsale, J. C.; Dilhaire, S.

    2011-05-01

    We have combined InfraRed thermography and thermal wave techniques to perform microscale, ultrafast (microsecond) temperature field measurements. The method is based on an IR camera coupled to a microscope and synchronized to the heat source by means of phase locked function generators. The principle is based on electronic stroboscopic sampling where the low IR camera acquisition frequency facq (25 Hz) undersamples a high frequency thermal wave. This technique permits the measurement of the emissive thermal response at a (microsecond) short time scale (microsecond) with the full frame mode of the IR camera with a spatial thermal resolution of 7 μm. Then it becomes possible to study 3D transient heat transfer in heterogeneous and high thermal conductive thin layers. Thus it is possible for the first time in our knowledge to achieve temperature field measurements in heterogeneous media within a wide range of time domains. The IR camera is now a suitable instrument for multiscale thermal analysis.

  2. Setting Educational Priorities: High Achievers Speak Out. White Paper.

    ERIC Educational Resources Information Center

    Dickeson, Robert C.

    Noting that high achieving Indiana high school students can provide important insights into the educational system in the state, this study examined the opinions of recipients of Ameritchieve recognition, National Merit finalists, African-American students who were National Achievement finalists, and national Hispanic Scholar finalists, all from…

  3. Flexible Fabrics with High Thermal Conductivity for Advanced Spacesuits

    NASA Technical Reports Server (NTRS)

    Trevino, Luis A.; Bue, Grant; Orndoff, Evelyne; Kesterson, Matt; Connel, John W.; Smith, Joseph G., Jr.; Southward, Robin E.; Working, Dennis; Watson, Kent A.; Delozier, Donovan M.

    2006-01-01

    This paper describes the effort and accomplishments for developing flexible fabrics with high thermal conductivity (FFHTC) for spacesuits to improve thermal performance, lower weight and reduce complexity. Commercial and additional space exploration applications that require substantial performance enhancements in removal and transport of heat away from equipment as well as from the human body can benefit from this technology. Improvements in thermal conductivity were achieved through the use of modified polymers containing thermally conductive additives. The objective of the FFHTC effort is to significantly improve the thermal conductivity of the liquid cooled ventilation garment by improving the thermal conductivity of the subcomponents (i.e., fabric and plastic tubes). This paper presents the initial system modeling studies, including a detailed liquid cooling garment model incorporated into the Wissler human thermal regulatory model, to quantify the necessary improvements in thermal conductivity and garment geometries needed to affect system performance. In addition, preliminary results of thermal conductivity improvements of the polymer components of the liquid cooled ventilation garment are presented. By improving thermal garment performance, major technology drivers will be addressed for lightweight, high thermal conductivity, flexible materials for spacesuits that are strategic technical challenges of the Exploration

  4. Test-Taking Strategies of High and Low Mathematics Achievers

    ERIC Educational Resources Information Center

    Hong, Eunsook; Sas, Maggie; Sas, John C.

    2006-01-01

    The authors explored test-preparation and test-taking strategies that high school students used in algebra tests. From a pool of high school students (N = 156), 61 students participated in interviews, and of those interviewed, 26 represented those who were high achieving as well as highly interested in mathematics (n = 15) vs. those who were low…

  5. Biculturalism and Academic Achievement of African American High School Students

    ERIC Educational Resources Information Center

    Rust, Jonathan P.; Jackson, Margo A.; Ponterotto, Joseph G.; Blumberg, Fran C.

    2011-01-01

    Biculturalism was examined as a factor that may positively affect the academic achievement of African American high school students, beyond cultural identity and self-esteem. Hierarchical regression analyses determined that cultural identity and academic self-esteem were important factors for academic achievement, but not biculturalism.…

  6. Tracking and Detracking: High Achievers in Massachusetts Middle Schools

    ERIC Educational Resources Information Center

    Loveless, Tom

    2009-01-01

    This study examines tracking--the practice of grouping students into separate classes or courses based on their prior academic achievement--at the middle-school level, and the percentage of high-achieving students in tracked and untracked schools. It focuses on Massachusetts, a leader in "reforming" tracking, and the changes that have…

  7. Mobility and Student Achievement in High Poverty Schools

    ERIC Educational Resources Information Center

    Dalton, Janet Denise

    2013-01-01

    Student mobility is an issue for high poverty schools in the shadow of increased rigor and accountability for student performance. Whereas mobility is not a sole cause for poor achievement, it is a contributing factor for students in poverty who are already considered to be at risk of low achievement. Student mobility creates a hardship for…

  8. Attitudes and Opinions from the Nation's High Achieving Teens: 29th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report presents the 1998 statistical findings of the annual survey to determine the attitudes of national high school student leaders. Questionnaires were completed by 3,123 high school juniors and seniors, all of whom were selected for recognition in "Who's Who among American High School Students." In addition to demographic information, the…

  9. Associations of Future Expectations, Negative Friends, and Academic Achievement in High-Achieving African American Adolescents

    ERIC Educational Resources Information Center

    Cunningham, Michael; Corprew, Charles S., III; Becker, Jonathan E.

    2009-01-01

    The relations of future expectations (general and academic) to academic outcomes were examined in a sample of 129 African American high-achieving adolescents (majority female participants, n = 92). This study was interested in the multidimensional nature of future expectations. Results from the study confirm the hypothesis that academic future…

  10. The "Renaissance Child": High Achievement and Gender in Late Modernity

    ERIC Educational Resources Information Center

    Skelton, Christine; Francis, Becky

    2012-01-01

    This paper draws on the concept of the "Renaissance Child" to illustrate the ways in which gender influences the opportunities and possibilities of high-achieving pupils. Using data from a study of 12-13-year high-achieving boys and girls based in schools in England, the paper considers the ways in which a group of popular boys was able to show an…

  11. High reflector absorptance measurements by the surface thermal lensing technique

    SciTech Connect

    Chow, R.; Taylor, J.R.; Wu, Z.L.; Krupka, R.; Yang, T.

    1996-11-01

    Surface thermal lensing is an alternate configuration of a photothermal deflection system that was used to measure low levels of optical absorption. The thermal lensing configuration facilitated the alignment of the pump and probe laser beams by using a larger diameter probe beam. This technique was applied to high performance optical coatings, specifically high reflectors at 511 nm, zero degrees angle of incidence. The absorptance of these coatings was previously measured using a high power copper vapor laser system. A high power copper laser beam is focused onto a -2 mm diameter spot. A thermal camera senses the temperature rise with respect to the rest of the coating. The temperature change, power density and beam diameter were used with an empirical formula that yields optical absorption. The surface thermal lensing technique was able to resolve absorption levels lower than that achieved with the copper laser method.

  12. The Effects of Block Scheduling on High School Academic Achievement

    ERIC Educational Resources Information Center

    Lewis, Chance W.; Dugan, James J.; Winokur, Marc A.; Cobb, Brian R.

    2005-01-01

    The effect of block scheduling on high school student achievement in mathematics and reading was investigated in this study through the use of an ex post-facto, longitudinal research design. Specifically, student scores from 9th and 11th-grade standardized tests were matched and sorted by junior high and high school attended. Outcome measures…

  13. Attitudes and Opinions from the Nation's High Achieving Teens: 28th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report details the 28th annual study to examine the attitudes of student leaders in U.S. high schools. Participating in the survey were 3,210 adolescents, primarily 16- and 17-year-olds, who had been featured in the 1997 edition of "Who's Who Among American High School Students." The report presents demographic information on the survey…

  14. Attitudes and Opinions from the Nation's High Achieving Teens: 27th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This report details the 27th annual study to examine the attitudes of student leaders in U.S. high schools. Participating in the survey were 3,370 adolescents, primarily 16- and 17-year-olds, who had been featured in the 1996 edition of "Who's Who Among American High School Students." The report presents demographic information on the survey…

  15. A Study on the Relationship between Logical Thinking Level and the Achievement in Enrichment Physics of School Science High Achievers.

    ERIC Educational Resources Information Center

    Kim, Young-Min; Lee, Sung-Yi

    2001-01-01

    Investigates science high achievers' achievement in enrichment physics and logical thinking levels, and analyzes the relationship between logical thinking level and achievement in enrichment physics of high achievers in science. Involves (n=35) 7th and 8th grade junior high school students in the study. Uses the Group Assessment of Logical…

  16. Student Achievement for Whom? High-Performing and Still "Playing the Game," the Meaning of School Achievement among High Achieving African American Students

    ERIC Educational Resources Information Center

    Wiggan, Greg

    2014-01-01

    The preponderance of the research on African American students has generally focused on issues of school failure and underperformance. While the literature on high achieving Black students is sparse, very little is known about these students' school experiences and the meanings that they assign to achievement. Using student-based inquiry…

  17. Attitudes and Opinions from the Nation's High Achieving Teens. 25th Annual Survey of High Achievers.

    ERIC Educational Resources Information Center

    Who's Who among American High School Students, Lake Forest, IL.

    This survey was conducted during the spring of 1994 for the purpose of determining the attitudes of student leaders in the nation's high schools. Eight thousand surveys were sent out to students, of which 3177 were returned. All students surveyed were members of the junior or senior class during the 1993-94 academic year. They were selected for…

  18. High Spatial Resolution Thermal Satellite Technologies

    NASA Technical Reports Server (NTRS)

    Ryan, Robert

    2003-01-01

    This document in the form of viewslides, reviews various low-cost alternatives to high spatial resolution thermal satellite technologies. There exists no follow-on to Landsat 7 or ASTER high spatial resolution thermal systems. This document reviews the results of the investigation in to the use of new technologies to create a low-cost useful alternative. Three suggested technologies are examined. 1. Conventional microbolometer pushbroom modes offers potential for low cost Landsat Data Continuity Mission (LDCM) thermal or ASTER capability with at least 60-120 ground sampling distance (GSD). 2. Backscanning could produce MultiSpectral Thermal Imager performance without cooled detectors. 3. Cooled detector could produce hyperspectral thermal class system or extremely high spatial resolution class instrument.

  19. Student Achievement Levels Raised at Chandler High School.

    ERIC Educational Resources Information Center

    Profiles, Programs & Products, 1983

    1983-01-01

    Chandler (Arizona) High School has reported a dramatic increase in student achievement levels since implementing a number of management, curriculum, and discipline policy changes. Among the program changes that contributed to these gains are: (1) creation of a positive school environment, with high expectations for teachers, emphasis on high…

  20. Brain Hemisphericity and Mathematics Achievement of High School Students

    ERIC Educational Resources Information Center

    Fernandez, Sanny F.

    2011-01-01

    This study aimed to find out the brain hemisphericity and mathematics achievement of high school students. The respondents of the study were the 168 first year high school students of Colegio de San Jose, during school year 2010-2011 who were chosen through stratified random sampling. The descriptive and interview methods of research were used in…

  1. Exploring High-Achieving Students' Images of Mathematicians

    ERIC Educational Resources Information Center

    Aguilar, Mario Sánchez; Rosas, Alejandro; Zavaleta, Juan Gabriel Molina; Romo-Vázquez, Avenilde

    2016-01-01

    The aim of this study is to describe the images that a group of high-achieving Mexican students hold of mathematicians. For this investigation, we used a research method based on the Draw-A-Scientist Test (DAST) with a sample of 63 Mexican high school students. The group of students' pictorial and written descriptions of mathematicians assisted us…

  2. High School Employment and Academic Achievement: A Note for Educators

    ERIC Educational Resources Information Center

    Keister, Mary; Hall, Joshua

    2010-01-01

    Educators are often in a position to affect student decisions to work during the school term. This study reviews and summarizes the literature on the effect that employment during high school has on academic achievement. The available evidence suggests that part-time jobs for high school students are beneficial as long as the number of hours…

  3. What Does Quality Programming Mean for High Achieving Students?

    ERIC Educational Resources Information Center

    Samudzi, Cleo

    2008-01-01

    The Missouri Academy of Science, Mathematics and Computing (Missouri Academy) is a two-year accelerated, early-entrance-to-college, residential school that matches the level, complexity and pace of the curriculum with the readiness and motivation of high achieving high school students. The school is a part of Northwest Missouri State University…

  4. Thermal disconnect for high-temperature batteries

    DOEpatents

    Jungst, Rudolph George; Armijo, James Rudolph; Frear, Darrel Richard

    2000-01-01

    A new type of high temperature thermal disconnect has been developed to protect electrical and mechanical equipment from damage caused by operation at extreme temperatures. These thermal disconnects allow continuous operation at temperatures ranging from 250.degree. C. to 450.degree. C., while rapidly terminating operation at temperatures 50.degree. C. to 150.degree. C. higher than the continuous operating temperature.

  5. High intensity, pulsed thermal neutron source

    DOEpatents

    Carpenter, J.M.

    1973-12-11

    This invention relates to a high intensity, pulsed thermal neutron source comprising a neutron-producing source which emits pulses of fast neutrons, a moderator block adjacent to the last neutron source, a reflector block which encases the fast neutron source and the moderator block and has a thermal neutron exit port extending therethrough from the moderator block, and a neutron energy- dependent decoupling reflector liner covering the interior surfaces of the thermal neutron exit port and surrounding all surfaces of the moderator block except the surface viewed by the thermal neutron exit port. (Official Gazette)

  6. An Analysis of High School Mathematics Achievement and English Language Arts Achievement as Predictors of Science Achievement

    ERIC Educational Resources Information Center

    Edwards, Anthony C.

    2012-01-01

    Science assessments require students to read and comprehend questions and to solve mathematical problems. The purpose of this study is to determine whether the following variables can be used to predict science achievement: English language arts achievement, mathematics achievement, socioeconomic status (SES), limited English proficiency (LEP)…

  7. High Reynolds Number Thermal Stability Experiments

    NASA Technical Reports Server (NTRS)

    Emens, Jessica M.; Brown, Sarah P.; Frederick Robert A., Jr.; Wood, A. John

    2004-01-01

    This work represents preliminary thermal stability results for liquid hydrocarbon fuels. High Reynolds Number Thermal Stability experiments with Jet A and RP-1 resulted in a quantitative measurement of the thermal stability. Each fuel flowed through a heated capillary tube that held the outlet temperature at 290 C. An optical pyrometer measured the surface temperature of the tube at 12 locations as a function of time. The High Reynolds Number Thermal Stability number was then determined using standards published by the American Society for Testing and Materials. The results for Jet A showed lower thermal stability than similar tests conducted at another facility. The RP-1 results are the first reported using this technique. Because the temperature rise on the capillary tube during testing for the RP-1 fuels was not significant, a new standard for the testing conditions should be developed for these types of fuels.

  8. Achievement of a low-outgassing white paint system for spacecraft thermal control

    NASA Technical Reports Server (NTRS)

    Seidenberg, B.; Park, J. J.; Clatterbuck, C.

    1972-01-01

    Test results and data for achieving a low-outgassing polymer resin suitable for potting or a paint pigment are presented. The resin, prepared in 0.5-kg (1-lb) batches, is acceptable for spacecraft use; its weight loss is less than 0.5 percent, and the volatile condensable materials are less than 0.05 percent. The paint adheres to a primed fiber glass or aluminum substrate. Results of UV irradiation, electron and proton radiation, and thermal cycling are presented.

  9. Supplementary Education: The Hidden Curriculum of High Academic Achievement

    ERIC Educational Resources Information Center

    Gordon, Edmund W., Ed.; Bridglall, Beatrice L., Ed.; Meroe, Aundra Saa, Ed.

    2004-01-01

    In this book, the editors argue that while access to schools that enable and expect academic achievement is a necessary ingredient for the education of students, schools alone may not be sufficient to ensure universally high levels of academic development. Supplemental educational experiences may also be needed. The idea of supplementary education…

  10. Self-Esteem and Academic Achievement of High School Students

    ERIC Educational Resources Information Center

    Moradi Sheykhjan, Tohid; Jabari, Kamran; Rajeswari, K.

    2014-01-01

    The primary purpose of this study was to determine the influence of self-esteem on academic achievement among high school students in Miandoab City of Iran. The methodology of the research is descriptive and correlation that descriptive and inferential statistics were used to analyze the data. Statistical Society includes male and female high…

  11. Student Achievement Levels Climb at Ribault Senior High School.

    ERIC Educational Resources Information Center

    Profiles, Programs & Products, 1983

    1983-01-01

    Ribault (Florida) Senior High School has reported a dramatic increase in student achievement levels since implementing a comprehensive college preparation curriculum. Among the program changes that contributed to those gains are: (1) the establishment and consistent enforcement of a strong discipline program, including rules for student conduct, a…

  12. Middle School Practices Improve Student Achievement in High Poverty Schools.

    ERIC Educational Resources Information Center

    Mertens, Steven B.; Flowers, Nancy

    2003-01-01

    Examined how interdisciplinary team practices and classroom instructional practices affected student achievement in high poverty middle schools in Arkansas, Louisiana, and Mississippi. Found that when the combined effects of family poverty level, teaming and common planning time, and duration of teaming were considered, there was a relationship…

  13. Student Achievement through the Development of Complete High School Culture

    ERIC Educational Resources Information Center

    Lamphere, Michael Frederick, Jr.

    2012-01-01

    This dissertation undertook an investigation of school culture and achievement in the high school setting. The national data set ELS:2002 was used as the pool of variables because it allows for a complete picture of school culture comprising students, parents, administrators, and teachers. The data were selected based on current literature and…

  14. Mercer Middle School Case Study: High Science and Math Achievement

    ERIC Educational Resources Information Center

    Washington State Board of Education, 2010

    2010-01-01

    To spotlight effective practices, the Washington State Board of Education (SBE) is highlighting schools that are closing achievement gaps and performing at high levels. In 2009, the SBE partnered with the Office of Superintendent of Public Instruction (OSPI) to create the Washington Accountability Index. The Index is a new way to measure schools'…

  15. Analysis of Three High-Achieving Young Adolescent Girls

    ERIC Educational Resources Information Center

    Lim, Jae Hoon; Chae, Jeong-Lim; Schinck-Mikel, Amelie G.; Watson, Jimmy

    2013-01-01

    This paper presents an in-depth cross-case analysis of three high-achieving young adolescent girls who had contrasting mathematics learning experiences during the first year of middle school. In particular, this study examines the foundation for their motivation, as well as the dominant mode of learning and academic engagement in relation to three…

  16. The High Trust Classroom: Raising Achievement from the Inside Out

    ERIC Educational Resources Information Center

    Moore, Lonnie

    2009-01-01

    This book provides a roadmap to developing a high-trust classroom, a classroom: (1) With increased student achievement; (2) With few discipline problems; (3) Where students are intrinsically motivated; and (4) Where the teacher can confidently use creative lesson planning. The author presents a simple step by step approach to earning the trust of…

  17. Best Practices for Achieving High, Rapid Reading Gains

    ERIC Educational Resources Information Center

    Carbo, Marie

    2008-01-01

    The percentage of students who read at the proficient level on the National Assessment of Educational Progress (NAEP) has not improved, and is appallingly low. In order for students to achieve high reading gains and become life-long readers, reading comprehension and reading enjoyment must be the top two goals. This article presents several…

  18. Relationship between High School Leadership Team Practices and Student Achievement

    ERIC Educational Resources Information Center

    McInnis, Timothy M.

    2009-01-01

    This study investigated if a relationship existed between student achievement in 10th grade Missouri Assessment Program mathematics and 11th grade communication arts scores in 2007 and high school leadership team perceptions of the extent to which they demonstrated leadership practices. The secondary purpose was to compare perceptional…

  19. Achievement of U.S. High-School Physics Students.

    ERIC Educational Resources Information Center

    Chandavarkar, Marilda S.; And Others

    1991-01-01

    Reports results of the Second International Science Study concerning achievement in physics of U.S. high school students. Makes comparisons between students of 13 other countries and U.S. students, between first- and second-year U.S. physics students, and between U.S. students tested in the mid-1980s and those tested in 1970. (MDH)

  20. Progress Lags in High School, Especially for Advanced Achievers

    ERIC Educational Resources Information Center

    Education Digest: Essential Readings Condensed for Quick Review, 2012

    2012-01-01

    This report by the Center on Education Policy (CEP), an independent nonprofit organization, examines trends in the achievement of high school students on the state reading/English language arts (ELA) and mathematics tests used for accountability under the No Child Left Behind Act (NCLB). This study confirms that there is reason for concern about…

  1. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect

    Jamil A. Khan

    2009-11-21

    Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

  2. Polyethylene nanofibres with very high thermal conductivities.

    PubMed

    Shen, Sheng; Henry, Asegun; Tong, Jonathan; Zheng, Ruiting; Chen, Gang

    2010-04-01

    Bulk polymers are generally regarded as thermal insulators, and typically have thermal conductivities on the order of 0.1 W m(-1) K(-1). However, recent work suggests that individual chains of polyethylene--the simplest and most widely used polymer--can have extremely high thermal conductivity. Practical applications of these polymers may also require that the individual chains form fibres or films. Here, we report the fabrication of high-quality ultra-drawn polyethylene nanofibres with diameters of 50-500 nm and lengths up to tens of millimetres. The thermal conductivity of the nanofibres was found to be as high as approximately 104 W m(-1) K(-1), which is larger than the conductivities of about half of the pure metals. The high thermal conductivity is attributed to the restructuring of the polymer chains by stretching, which improves the fibre quality toward an 'ideal' single crystalline fibre. Such thermally conductive polymers are potentially useful as heat spreaders and could supplement conventional metallic heat-transfer materials, which are used in applications such as solar hot-water collectors, heat exchangers and electronic packaging. PMID:20208547

  3. Parent Involvement Practices of High-Achieving Elementary Science Students

    NASA Astrophysics Data System (ADS)

    Waller, Samara Susan

    This study addressed a prevalence of low achievement in science courses in an urban school district in Georgia. National leaders and educators have identified the improvement of science proficiency as critical to the future of American industry. The purpose of this study was to examine parent involvement in this school district and its contribution to the academic achievement of successful science students. Social capital theory guided this study by suggesting that students achieve best when investments are made into their academic and social development. A collective case study qualitative research design was used to interview 9 parent participants at 2 elementary schools whose children scored in the exceeds category on the Science CRCT. The research questions focused on what these parents did at home to support their children's academic achievement. Data were collected using a semi-structured interview protocol and analyzed through the categorical aggregation of transcribed interviews. Key findings revealed that the parents invested time and resources in 3 practices: communicating high expectations, supporting and developing key skills, and communicating with teachers. These findings contribute to social change at both the local and community level by creating a starting point for teachers, principals, and district leaders to reexamine the value of parent input in the educational process, and by providing data to support the revision of current parent involvement policies. Possibilities for further study building upon the findings of this study may focus on student perceptions of their parents' parenting as it relates to their science achievement.

  4. High precision thermal neutron detectors

    SciTech Connect

    Radeka, V.; Schaknowski, N.A.; Smith, G.C.; Yu, B.

    1994-12-31

    Two-dimensional position sensitive detectors are indispensable in neutron diffraction experiments for determination of molecular and crystal structures in biology, solid-state physics and polymer chemistry. Some performance characteristics of these detectors are elementary and obvious, such as the position resolution, number of resolution elements, neutron detection efficiency, counting rate and sensitivity to gamma-ray background. High performance detectors are distinguished by more subtle characteristics such as the stability of the response (efficiency) versus position, stability of the recorded neutron positions, dynamic range, blooming or halo effects. While relatively few of them are needed around the world, these high performance devices are sophisticated and fairly complex, their development requires very specialized efforts. In this context, we describe here a program of detector development, based on {sup 3}He filled proportional chambers, which has been underway for some years at the Brookhaven National Laboratory. Fundamental approaches and practical considerations are outlined that have resulted in a series of high performance detectors with the best known position resolution, position stability, uniformity of response and reliability over time, for devices of this type.

  5. The Will to Achieve: A Phenomenological Study of the Experiences of African American High Achieving Students and Their Parents

    ERIC Educational Resources Information Center

    Spencer, Natalie Faye

    2012-01-01

    The purpose of this research study was to understand the experiences of high achieving African American students and their parents. The experiences of high achieving African American students and their parents have been missing from literature on the academic achievement of African American students. Much of the literature that has been published…

  6. Thermal boundary conductance enhancement using experimentally achievable nanostructured interfaces - analytical study combined with molecular dynamics simulation.

    PubMed

    Lee, Eungkyu; Zhang, Teng; Hu, Ming; Luo, Tengfei

    2016-06-22

    Interfacial thermal resistance presents great challenges to the thermal management of modern electronics. In this work, we perform an analytical study to enhance the thermal boundary conductance (TBC) of nanostructured interfaces with square-shape pillar arrays, extendable to the characteristic lengths that can be fabricated in practice. As a representative system, we investigate a SiC substrate with the square-shape pillar array combined with epitaxial GaN as the nanostructured interface. By applying a first-order ray tracing method and molecular dynamics simulations to analyze phonon incidence and transmission at the nanostructured interface, we systematically study the impact of the characteristic dimensions of the pillar array on the TBC. Based on the multi-scale analysis we provide a general guideline to optimize the nanostructured interfaces to achieve higher TBC, demonstrating that the optimized TBC value of the nanostructured SiC/GaN interfaces can be 42% higher than that of the planar SiC/GaN interfaces without nanostructures. The model used and results obtained in this study will guide the further experimental realization of nanostructured interfaces for better thermal management in microelectronics. PMID:27275647

  7. High thermal conductivity connector having high electrical isolation

    DOEpatents

    Nieman, Ralph C.; Gonczy, John D.; Nicol, Thomas H.

    1995-01-01

    A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

  8. Highly thermally conductive papers with percolative layered boron nitride nanosheets.

    PubMed

    Zhu, Hongli; Li, Yuanyuan; Fang, Zhiqiang; Xu, Jiajun; Cao, Fangyu; Wan, Jiayu; Preston, Colin; Yang, Bao; Hu, Liangbing

    2014-04-22

    In this work, we report a dielectric nanocomposite paper with layered boron nitride (BN) nanosheets wired by one-dimensional (1D) nanofibrillated cellulose (NFC) that has superior thermal and mechanical properties. These nanocomposite papers are fabricated from a filtration of BN and NFC suspensions, in which NFC is used as a stabilizer to stabilize BN nanosheets. In these nanocomposite papers, two-dimensional (2D) nanosheets form a thermally conductive network, while 1D NFC provides mechanical strength. A high thermal conductivity has been achieved along the BN paper surface (up to 145.7 W/m K for 50 wt % of BN), which is an order of magnitude higher than that in randomly distributed BN nanosheet composites and is even comparable to the thermal conductivity of aluminum alloys. Such a high thermal conductivity is mainly attributed to the structural alignment within the BN nanosheet papers; the effects of the interfacial thermal contact resistance are minimized by the fact that the heat transfer is in the direction parallel to the interface between BN nanosheets and that a large contact area occurs between BN nanosheets. PMID:24601534

  9. Experiences of High-Achieving High School Students Who Have Taken Multiple Concurrent Advanced Placement Courses

    ERIC Educational Resources Information Center

    Milburn, Kristine M.

    2011-01-01

    Problem: An increasing number of high-achieving American high school students are enrolling in multiple Advanced Placement (AP) courses. As a result, high schools face a growing need to understand the impact of taking multiple AP courses concurrently on the social-emotional lives of high-achieving students. Procedures: This phenomenological…

  10. Interface Strategy To Achieve Tunable High Frequency Attenuation.

    PubMed

    Lv, Hualiang; Zhang, Haiqian; Ji, Guangbin; Xu, Zhichuan J

    2016-03-16

    Among all polarizations, the interface polarization effect is the most effective, especially at high frequency. The design of various ferrite/iron interfaces can significantly enhance the materials' dielectric loss ability at high frequency. This paper presents a simple method to generate ferrite/iron interfaces to enhance the microwave attenuation at high frequency. The ferrites were coated onto carbonyl iron and could be varied to ZnFe2O4, CoFe2O4, Fe3O4, and NiFe2O4. Due to the ferrite/iron interface inducing a stronger dielectric loss effect, all of these materials achieved broad effective frequency width at a coating layer as thin as 1.5 mm. In particular, an effective frequency width of 6.2 GHz could be gained from the Fe@NiFe2O4 composite. PMID:26918285

  11. High velocity pulsed plasma thermal spray

    NASA Astrophysics Data System (ADS)

    Witherspoon, F. D.; Massey, D. W.; Kincaid, R. W.; Whichard, G. C.; Mozhi, T. A.

    2002-03-01

    The quality and durability of coatings produced by many thermal spray techniques could be improved by increasing the velocity with which coating particles impact the substrate. Additionally, better control of the chemical and thermal environment seen by the particles during flight is crucial to the quality of the coating. A high velocity thermal spray device is under development through a Ballistic Missile Defense Organization Small Business Innovation Research (SBIR) project, which provides significantly higher impact velocity for accelerated particles than is currently available with existing thermal spray devices. This device utilizes a pulsed plasma as the accelerative medium for powders introduced into the barrel. Recent experiments using a particle imaging diagnostic system showed that the device can accelerate stainless steel and WC-Co powders to velocities ranging from 1500 to 2200 m/s. These high velocities are accomplished without the use of combustible gases and without the need of a vacuum chamber, while maintaining an inert atmosphere for the particles during acceleration. The high velocities corresponded well to modeling predictions, and these same models suggest that velocities as high as 3000 m/s or higher are possible.

  12. Unlocking Emergent Talent: Supporting High Achievement of Low-Income, High Ability Students

    ERIC Educational Resources Information Center

    Olszewski-Kubilius, Paula; Clarenbach, Jane

    2012-01-01

    This report takes a comprehensive look at achievement for low-income promising learners--past, present, and future. At its core, it challenges the nation to move beyond its near-singular focus of achieving minimum performance for all students, to identifying and developing the talent of all students who are capable of high achievement, including…

  13. THERMAL ANALYSIS OF GEOLOGIC HIGH-LEVEL RADIOACTIVE WASTE PACKAGES

    SciTech Connect

    Hensel, S.; Lee, S.

    2010-04-20

    The engineering design of disposal of the high level waste (HLW) packages in a geologic repository requires a thermal analysis to provide the temperature history of the packages. Calculated temperatures are used to demonstrate compliance with criteria for waste acceptance into the geologic disposal gallery system and as input to assess the transient thermal characteristics of the vitrified HLW Package. The objective of the work was to evaluate the thermal performance of the supercontainer containing the vitrified HLW in a non-backfilled and unventilated underground disposal gallery. In order to achieve the objective, transient computational models for a geologic vitrified HLW package were developed by using a computational fluid dynamics method, and calculations for the HLW disposal gallery of the current Belgian geological repository reference design were performed. An initial two-dimensional model was used to conduct some parametric sensitivity studies to better understand the geologic system's thermal response. The effect of heat decay, number of co-disposed supercontainers, domain size, humidity, thermal conductivity and thermal emissivity were studied. Later, a more accurate three-dimensional model was developed by considering the conduction-convection cooling mechanism coupled with radiation, and the effect of the number of supercontainers (3, 4 and 8) was studied in more detail, as well as a bounding case with zero heat flux at both ends. The modeling methodology and results of the sensitivity studies will be presented.

  14. High Fidelity Probe and Mitigation of Mirror Thermal Fluctuations

    NASA Astrophysics Data System (ADS)

    Chalermsongsak, Tara

    Thermal noise arising from mechanical loss in high reflective dielectric coatings is a significant source of noise in precision optical measurements. In particular, Advanced LIGO, a large scale interferometer aiming to observed gravitational wave, is expected to be limited by coating thermal noise in the most sensitive region around 30-300 Hz. Various theoretical calculations for predicting coating Brownian noise have been proposed. However, due to the relatively limited knowledge of the coating material properties, an accurate approximation of the noise cannot be achieved. A testbed that can directly observed coating thermal noise close to Advanced LIGO band will serve as an indispensable tool to verify the calculations, study material properties of the coating, and estimate the detector's performance. This dissertation reports a setup that has sensitivity to observe wide band (10Hz to 1kHz) thermal noise from fused silica/tantala coating at room temperature from fixed-spacer Fabry-Perot cavities. Important fundamental noises and technical noises associated with the setup are discussed. The coating loss obtained from the measurement agrees with results reported in the literature. The setup serves as a testbed to study thermal noise in high reflective mirrors from different materials. One example is a heterostructure of Al xGa1-xAs (AlGaAs). An optimized design to minimize thermo-optic noise in the coating is proposed and discussed in this work.

  15. Highly thermally conductive and mechanically strong graphene fibers.

    PubMed

    Xin, Guoqing; Yao, Tiankai; Sun, Hongtao; Scott, Spencer Michael; Shao, Dali; Wang, Gongkai; Lian, Jie

    2015-09-01

    Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is the thinnest, strongest, and stiffest known material and an excellent conductor of heat and electricity. However, these superior properties have yet to be realized for graphene-derived macroscopic structures such as graphene fibers. We report the fabrication of graphene fibers with high thermal and electrical conductivity and enhanced mechanical strength. The inner fiber structure consists of large-sized graphene sheets forming a highly ordered arrangement intercalated with small-sized graphene sheets filling the space and microvoids. The graphene fibers exhibit a submicrometer crystallite domain size through high-temperature treatment, achieving an enhanced thermal conductivity up to 1290 watts per meter per kelvin. The tensile strength of the graphene fiber reaches 1080 megapascals. PMID:26339027

  16. Highly thermally conductive and mechanically strong graphene fibers

    NASA Astrophysics Data System (ADS)

    Xin, Guoqing; Yao, Tiankai; Sun, Hongtao; Scott, Spencer Michael; Shao, Dali; Wang, Gongkai; Lian, Jie

    2015-09-01

    Graphene, a single layer of carbon atoms bonded in a hexagonal lattice, is the thinnest, strongest, and stiffest known material and an excellent conductor of heat and electricity. However, these superior properties have yet to be realized for graphene-derived macroscopic structures such as graphene fibers. We report the fabrication of graphene fibers with high thermal and electrical conductivity and enhanced mechanical strength. The inner fiber structure consists of large-sized graphene sheets forming a highly ordered arrangement intercalated with small-sized graphene sheets filling the space and microvoids. The graphene fibers exhibit a submicrometer crystallite domain size through high-temperature treatment, achieving an enhanced thermal conductivity up to 1290 watts per meter per kelvin. The tensile strength of the graphene fiber reaches 1080 megapascals.

  17. Thermal interface pastes nanostructured for high performance

    NASA Astrophysics Data System (ADS)

    Lin, Chuangang

    Thermal interface materials in the form of pastes are needed to improve thermal contacts, such as that between a microprocessor and a heat sink of a computer. High-performance and low-cost thermal pastes have been developed in this dissertation by using polyol esters as the vehicle and various nanoscale solid components. The proportion of a solid component needs to be optimized, as an excessive amount degrades the performance, due to the increase in the bond line thickness. The optimum solid volume fraction tends to be lower when the mating surfaces are smoother, and higher when the thermal conductivity is higher. Both a low bond line thickness and a high thermal conductivity help the performance. When the surfaces are smooth, a low bond line thickness can be even more important than a high thermal conductivity, as shown by the outstanding performance of the nanoclay paste of low thermal conductivity in the smooth case (0.009 mum), with the bond line thickness less than 1 mum, as enabled by low storage modulus G', low loss modulus G" and high tan delta. However, for rough surfaces, the thermal conductivity is important. The rheology affects the bond line thickness, but it does not correlate well with the performance. This study found that the structure of carbon black is an important parameter that governs the effectiveness of a carbon black for use in a thermal paste. By using a carbon black with a lower structure (i.e., a lower DBP value), a thermal paste that is more effective than the previously reported carbon black paste was obtained. Graphite nanoplatelet (GNP) was found to be comparable in effectiveness to carbon black (CB) pastes for rough surfaces, but it is less effective for smooth surfaces. At the same filler volume fraction, GNP gives higher thermal conductivity than carbon black paste. At the same pressure, GNP gives higher bond line thickness than CB (Tokai or Cabot). The effectiveness of GNP is limited, due to the high bond line thickness. A

  18. Achieving high energy absorption capacity in cellular bulk metallic glasses

    PubMed Central

    Chen, S. H.; Chan, K. C.; Wu, F. F.; Xia, L.

    2015-01-01

    Cellular bulk metallic glasses (BMGs) have exhibited excellent energy-absorption performance by inheriting superior strength from the parent BMGs. However, how to achieve high energy absorption capacity in cellular BMGs is vital but mysterious. In this work, using step-by-step observations of the deformation evolution of a series of cellular BMGs, the underlying mechanisms for the remarkable energy absorption capacity have been investigated by studying two influencing key factors: the peak stress and the decay of the peak stress during the plastic-flow plateau stages. An analytical model of the peak stress has been proposed, and the predicted results agree well with the experimental data. The decay of the peak stress has been attributed to the geometry change of the macroscopic cells, the formation of shear bands in the middle of the struts, and the “work-softening” nature of BMGs. The influencing factors such as the effect of the strut thickness and the number of unit cells have also been investigated and discussed. Strategies for achieving higher energy absorption capacity in cellular BMGs have been proposed. PMID:25973781

  19. Achieving high energy absorption capacity in cellular bulk metallic glasses

    NASA Astrophysics Data System (ADS)

    Chen, S. H.; Chan, K. C.; Wu, F. F.; Xia, L.

    2015-05-01

    Cellular bulk metallic glasses (BMGs) have exhibited excellent energy-absorption performance by inheriting superior strength from the parent BMGs. However, how to achieve high energy absorption capacity in cellular BMGs is vital but mysterious. In this work, using step-by-step observations of the deformation evolution of a series of cellular BMGs, the underlying mechanisms for the remarkable energy absorption capacity have been investigated by studying two influencing key factors: the peak stress and the decay of the peak stress during the plastic-flow plateau stages. An analytical model of the peak stress has been proposed, and the predicted results agree well with the experimental data. The decay of the peak stress has been attributed to the geometry change of the macroscopic cells, the formation of shear bands in the middle of the struts, and the “work-softening” nature of BMGs. The influencing factors such as the effect of the strut thickness and the number of unit cells have also been investigated and discussed. Strategies for achieving higher energy absorption capacity in cellular BMGs have been proposed.

  20. Achieving High Resolution Timer Events in Virtualized Environment.

    PubMed

    Adamczyk, Blazej; Chydzinski, Andrzej

    2015-01-01

    Virtual Machine Monitors (VMM) have become popular in different application areas. Some applications may require to generate the timer events with high resolution and precision. This however may be challenging due to the complexity of VMMs. In this paper we focus on the timer functionality provided by five different VMMs-Xen, KVM, Qemu, VirtualBox and VMWare. Firstly, we evaluate resolutions and precisions of their timer events. Apparently, provided resolutions and precisions are far too low for some applications (e.g. networking applications with the quality of service). Then, using Xen virtualization we demonstrate the improved timer design that greatly enhances both the resolution and precision of achieved timer events. PMID:26177366

  1. Progress on achieving the ICF conditions needed for high gain

    SciTech Connect

    Lindl, J.D.

    1988-12-23

    Progress during the past two years has moved us much closer to demonstrating the scientific and technological requirements for high gain ICF in the laboratory. This progress has been made possible by operating at the third harmonic of 1..mu..m light which dramatically reduces concern about hot electrons and by advances in diagnostics such as 100 ps x-ray framing cameras which greatly increase the data available from each experiment. Making use of many of these new capabilities, major improvements in confinement conditions have been achieved for ICF implosions. In particular, in an optimized hohlraum on Nova, radiation driven implosions with convergence ratio in excess of 30 (volume compression /approximately/3 /times/ 10/sup 4/) have performed essentially as predicted by spherical implosion calculations. This paper presents these results as well as examples of advances in several other areas and discusses the implications for the future of ICF with lasers and heavy ion beam drivers. 8 refs., 10 figs.

  2. Achieving High Resolution Timer Events in Virtualized Environment

    PubMed Central

    Adamczyk, Blazej; Chydzinski, Andrzej

    2015-01-01

    Virtual Machine Monitors (VMM) have become popular in different application areas. Some applications may require to generate the timer events with high resolution and precision. This however may be challenging due to the complexity of VMMs. In this paper we focus on the timer functionality provided by five different VMMs—Xen, KVM, Qemu, VirtualBox and VMWare. Firstly, we evaluate resolutions and precisions of their timer events. Apparently, provided resolutions and precisions are far too low for some applications (e.g. networking applications with the quality of service). Then, using Xen virtualization we demonstrate the improved timer design that greatly enhances both the resolution and precision of achieved timer events. PMID:26177366

  3. Thermal fuse for high-temperature batteries

    DOEpatents

    Jungst, Rudolph G.; Armijo, James R.; Frear, Darrel R.

    2000-01-01

    A thermal fuse, preferably for a high-temperature battery, comprising leads and a body therebetween having a melting point between approximately 400.degree. C. and 500.degree. C. The body is preferably an alloy of Ag--Mg, Ag--Sb, Al--Ge, Au--In, Bi--Te, Cd--Sb, Cu--Mg, In--Sb, Mg--Pb, Pb--Pd, Sb--Zn, Sn--Te, or Mg--Al.

  4. Achieving ultra-high temperatures with a resistive emitter array

    NASA Astrophysics Data System (ADS)

    Danielson, Tom; Franks, Greg; Holmes, Nicholas; LaVeigne, Joe; Matis, Greg; McHugh, Steve; Norton, Dennis; Vengel, Tony; Lannon, John; Goodwin, Scott

    2016-05-01

    The rapid development of very-large format infrared detector arrays has challenged the IR scene projector community to also develop larger-format infrared emitter arrays to support the testing of systems incorporating these detectors. In addition to larger formats, many scene projector users require much higher simulated temperatures than can be generated with current technology in order to fully evaluate the performance of their systems and associated processing algorithms. Under the Ultra High Temperature (UHT) development program, Santa Barbara Infrared Inc. (SBIR) is developing a new infrared scene projector architecture capable of producing both very large format (>1024 x 1024) resistive emitter arrays and improved emitter pixel technology capable of simulating very high apparent temperatures. During earlier phases of the program, SBIR demonstrated materials with MWIR apparent temperatures in excess of 1400 K. New emitter materials have subsequently been selected to produce pixels that achieve even higher apparent temperatures. Test results from pixels fabricated using the new material set will be presented and discussed. A 'scalable' Read In Integrated Circuit (RIIC) is also being developed under the same UHT program to drive the high temperature pixels. This RIIC will utilize through-silicon via (TSV) and Quilt Packaging (QP) technologies to allow seamless tiling of multiple chips to fabricate very large arrays, and thus overcome the yield limitations inherent in large-scale integrated circuits. Results of design verification testing of the completed RIIC will be presented and discussed.

  5. How to achieve high-level expression of microbial enzymes

    PubMed Central

    Liu, Long; Yang, Haiquan; Shin, Hyun-dong; Chen, Rachel R.; Li, Jianghua; Du, Guocheng; Chen, Jian

    2013-01-01

    Microbial enzymes have been used in a large number of fields, such as chemical, agricultural and biopharmaceutical industries. The enzyme production rate and yield are the main factors to consider when choosing the appropriate expression system for the production of recombinant proteins. Recombinant enzymes have been expressed in bacteria (e.g., Escherichia coli, Bacillus and lactic acid bacteria), filamentous fungi (e.g., Aspergillus) and yeasts (e.g., Pichia pastoris). The favorable and very advantageous characteristics of these species have resulted in an increasing number of biotechnological applications. Bacterial hosts (e.g., E. coli) can be used to quickly and easily overexpress recombinant enzymes; however, bacterial systems cannot express very large proteins and proteins that require post-translational modifications. The main bacterial expression hosts, with the exception of lactic acid bacteria and filamentous fungi, can produce several toxins which are not compatible with the expression of recombinant enzymes in food and drugs. However, due to the multiplicity of the physiological impacts arising from high-level expression of genes encoding the enzymes and expression hosts, the goal of overproduction can hardly be achieved, and therefore, the yield of recombinant enzymes is limited. In this review, the recent strategies used for the high-level expression of microbial enzymes in the hosts mentioned above are summarized and the prospects are also discussed. We hope this review will contribute to the development of the enzyme-related research field. PMID:23686280

  6. Effects of Partner's Ability on the Achievement and Conceptual Organization of High-Achieving Fifth-Grade Students.

    ERIC Educational Resources Information Center

    Carter, Glenda; Jones, M. Gail; Rua, Melissa

    2003-01-01

    Investigates high-achieving fifth-grade students' achievement gains and conceptual reorganization on convection. Features an instructional sequence of three dyadic inquiry investigations related to convection currents as well as pre- and post-assessment consisting of a multiple-choice test, a card sorting task, construction of a concept map, and…

  7. Comparison of the Level of Using Metacognitive Strategies during Study between High Achieving and Low Achieving Prospective Teachers

    ERIC Educational Resources Information Center

    Doganay, Ahmet; Demir, Ozden

    2011-01-01

    The main purpose of this study is to compare the level of using metacognitive strategies during study between high achieving and low achieving prospective classroom teachers. This study was designed as a mixed method study. Metacognitive Learning Strategies Scale developed by Namlu (2004) was used to measure the use of metacognitive strategies…

  8. Gender Differences in Attitudes toward Mathematics between Low-Achieving and High-Achieving Fifth Grade Elementary Students.

    ERIC Educational Resources Information Center

    Rathbone, A. Sue

    Possible gender differences in attitudes toward mathematics were studied between low-achieving and high-achieving fifth-grade students in selected elementary schools within a large, metropolitan area. The attitudes of pre-adolescent children at an intermediate grade level were assessed to determine the effects of rapidly emerging gender-related…

  9. Metal stud wall systems -- Thermal disaster, or modern wall systems with highly efficient thermal insulation?

    SciTech Connect

    Kosny, J.; Christian, J.E.; Desjarlais, A.O.

    1997-11-01

    Because steel has higher thermal conductivity than wood and intense heat transfer occurs through the metal wall components, thermal performances of a metal stud wall are significantly lower than for similar wood stud walls. A reduction of the in-cavity R-value caused by the wood studs is about 10% in wood stud walls. That is why metal stud walls are believed to be considerably less thermally effective than similar made of wood. However, properly designed metal stud walls can be as thermally effective as wood stud walls. Relatively high R-values may be achieved by installing insulating sheathing, which is widely used as a remedy for a weak thermal performance of metal stud walls. A series of the promising metal stud wall configurations is analyzed using results of finite difference computer modeling and guarded hotbox tests. Some of these walls were designed and tested in the ORNL Building Technology Center, some were tested in other laboratories, and some walls were developed and forgotten long time ago. Also, a novel concept of combined foam-metal studs is considered. The main aim of the present paper is to prove that it is possible to build metal stud walls which perform as well as wood stud walls. The key lies in designing; metal stud wall systems have to be treated in a special way with particular consideration to the high thermal conduction of metal components. In the discussed collection of the efficient metal stud wall configurations, reductions of the in-cavity R-value caused by metal studs are between 10 and 20%.

  10. Graphene oxide immobilized enzymes show high thermal and solvent stability

    NASA Astrophysics Data System (ADS)

    Hermanová, Soňa; Zarevúcká, Marie; Bouša, Daniel; Pumera, Martin; Sofer, Zdeněk

    2015-03-01

    The thermal and solvent tolerance of enzymes is highly important for their industrial use. We show here that the enzyme lipase from Rhizopus oryzae exhibits exceptionally high thermal stability and high solvent tolerance and even increased activity in acetone when immobilized onto a graphene oxide (GO) nanosupport prepared by Staudenmaier and Brodie methods. We studied various forms of immobilization of the enzyme: by physical adsorption, covalent attachment, and additional crosslinking. The activity recovery was shown to be dependent on the support type, enzyme loading and immobilization procedure. Covalently immobilized lipase showed significantly better resistance to heat inactivation (the activity recovery was 65% at 70 °C) in comparison with the soluble counterpart (the activity recovery was 65% at 40 °C). Physically adsorbed lipase achieved over 100% of the initial activity in a series of organic solvents. These findings, showing enhanced thermal stability and solvent tolerance of graphene oxide immobilized enzyme, will have a profound impact on practical industrial scale uses of enzymes for the conversion of lipids into fuels.The thermal and solvent tolerance of enzymes is highly important for their industrial use. We show here that the enzyme lipase from Rhizopus oryzae exhibits exceptionally high thermal stability and high solvent tolerance and even increased activity in acetone when immobilized onto a graphene oxide (GO) nanosupport prepared by Staudenmaier and Brodie methods. We studied various forms of immobilization of the enzyme: by physical adsorption, covalent attachment, and additional crosslinking. The activity recovery was shown to be dependent on the support type, enzyme loading and immobilization procedure. Covalently immobilized lipase showed significantly better resistance to heat inactivation (the activity recovery was 65% at 70 °C) in comparison with the soluble counterpart (the activity recovery was 65% at 40 °C). Physically adsorbed

  11. Optimal microelectromechanical systems (MEMS) device for achieving high pyroelectric response of AlN

    NASA Astrophysics Data System (ADS)

    Kebede, Bemnnet; Coutu, Ronald A.; Starman, LaVern

    2014-03-01

    This paper discusses research being conducted on aluminum nitride (AlN) as a pyroelectric material for use in detecting applications. AlN is being investigated because of its high pyroelectric coefficient, thermal stability, and high Curie temperature. In order to determine suitability of the pyroelectric properties of AlN for use as a detector, testing of several devices was conducted. These devices were fabricated using microelectromechanical systems (MEMS) fabrication processes; the devices were also designed to allow for voltage and current measurements. The deposited AlN films used were 150 nm - 300 nm in thickness. Thin-films were used to rapidly increase the temperature response after the thermal stimulus was applied to the pyroelectric material. This is important because the pyroelectric effect is directly proportional to the rate of temperature change. The design used was a face-electrode bridge that provides thermal isolation which minimizes heat loss to the substrate, thereby increasing operation frequency of the pyroelectric device. A thermal stimulus was applied to the pyroelectric material and the response was measured across the electrodes. A thermal imaging camera was used to monitor the changes in temperature. Throughout the testing process, the annealing temperatures, type of layers, and thicknesses were also varied. These changes resulted in improved MEMS designs, which were fabricated to obtain an optimal design configuration for achieving a high pyroelectric response. A pyroelectric voltage response of 38.9 mVp-p was measured without filtering, 12.45 mVp-p was measured in the infrared (IR) region using a Si filter, and 6.38 mVp-p was measured in the short wavelength IR region using a long pass filter. The results showed that AlN's pyroelectric properties can be used in detecting applications.

  12. Safety improvements in high pressure thermal machines

    SciTech Connect

    Otters, J.L.

    1988-02-09

    In a thermal machine of the type including a machine body having a main axis extending between a thermal end and a work end, a working fluid at relatively high pressure in a working fluid chamber defined in the body and a displacer element reciprocable within the chamber for subjecting the fluid to a thermodynamic cycle in cooperation with a reciprocable work piston, the improvement is described comprising outer shell means enclosing the machine body for maintaining a substantially sealed atmosphere about the machine body, and diffuser means arranged between the machine body and the outer shell means for diffusing a shock wave traveling towards the outer shell means resulting from explosive failure of the machine body and for shielding the outer shell means against fragments projected upon such failure.

  13. High-performance flat-panel solar thermoelectric generators with high thermal concentration.

    PubMed

    Kraemer, Daniel; Poudel, Bed; Feng, Hsien-Ping; Caylor, J Christopher; Yu, Bo; Yan, Xiao; Ma, Yi; Wang, Xiaowei; Wang, Dezhi; Muto, Andrew; McEnaney, Kenneth; Chiesa, Matteo; Ren, Zhifeng; Chen, Gang

    2011-07-01

    The conversion of sunlight into electricity has been dominated by photovoltaic and solar thermal power generation. Photovoltaic cells are deployed widely, mostly as flat panels, whereas solar thermal electricity generation relying on optical concentrators and mechanical heat engines is only seen in large-scale power plants. Here we demonstrate a promising flat-panel solar thermal to electric power conversion technology based on the Seebeck effect and high thermal concentration, thus enabling wider applications. The developed solar thermoelectric generators (STEGs) achieved a peak efficiency of 4.6% under AM1.5G (1 kW m(-2)) conditions. The efficiency is 7-8 times higher than the previously reported best value for a flat-panel STEG, and is enabled by the use of high-performance nanostructured thermoelectric materials and spectrally-selective solar absorbers in an innovative design that exploits high thermal concentration in an evacuated environment. Our work opens up a promising new approach which has the potential to achieve cost-effective conversion of solar energy into electricity. PMID:21532584

  14. On-chip integration and high-speed switching of multi-wavelength narrowband thermal emitters

    NASA Astrophysics Data System (ADS)

    Inoue, Takuya; De Zoysa, Menaka; Asano, Takashi; Noda, Susumu

    2016-02-01

    We experimentally demonstrate the high-speed, on-chip wavelength switching of thermal emission in the mid-infrared region. Our device consists of multiple integrated thermal emitters of different colors, each of which is composed of quantum wells and a photonic crystal. On current injection, the device exhibits narrowband (Q > 70) thermal emission with low electric power consumption. By applying a reverse bias to each section of the device, we achieve high-speed (>kHz) switching of multiple thermal emission wavelengths, opening a route towards compact, highly efficient mid-infrared light sources for various sensing applications.

  15. Achieving High Throughput for Data Transfer over ATM Networks

    NASA Technical Reports Server (NTRS)

    Johnson, Marjory J.; Townsend, Jeffrey N.

    1996-01-01

    File-transfer rates for ftp are often reported to be relatively slow, compared to the raw bandwidth available in emerging gigabit networks. While a major bottleneck is disk I/O, protocol issues impact performance as well. Ftp was developed and optimized for use over the TCP/IP protocol stack of the Internet. However, TCP has been shown to run inefficiently over ATM. In an effort to maximize network throughput, data-transfer protocols can be developed to run over UDP or directly over IP, rather than over TCP. If error-free transmission is required, techniques for achieving reliable transmission can be included as part of the transfer protocol. However, selected image-processing applications can tolerate a low level of errors in images that are transmitted over a network. In this paper we report on experimental work to develop a high-throughput protocol for unreliable data transfer over ATM networks. We attempt to maximize throughput by keeping the communications pipe full, but still keep packet loss under five percent. We use the Bay Area Gigabit Network Testbed as our experimental platform.

  16. High-Achieving High School Students and Not so High-Achieving College Students: A Look at Lack of Self-Control, Academic Ability, and Performance in College

    ERIC Educational Resources Information Center

    Honken, Nora B.; Ralston, Patricia A. S.

    2013-01-01

    This study investigated the relationship among lack of self-control, academic ability, and academic performance for a cohort of freshman engineering students who were, with a few exceptions, extremely high achievers in high school. Structural equation modeling analysis led to the conclusion that lack of self-control in high school, as measured by…

  17. Learning Styles and High School Students' Chemistry Achievement

    ERIC Educational Resources Information Center

    Uzuntiryaki, Esen

    2007-01-01

    The aim of the present study was to investigate the effects of students' learning styles on their chemistry achievement, and whether matching between teaching and learning styles also affects students' chemistry achievement. Two hundred and sixty-five tenth-grade students enrolled in a chemistry course and seven chemistry teachers participated in…

  18. Does Recreational Computer Use Affect High School Achievement?

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Berland, Matthew

    2013-01-01

    Historically, the relationship between student academic achievement and use of computers for fun and video gaming has been described from a multitude of perspectives, from positive, to negative, to neutral. However, recent research has indicated that computer use and video gaming may be positively associated with achievement, yet these studies…

  19. Student Perception of Academic Achievement Factors at High School

    ERIC Educational Resources Information Center

    Bahar, Mustafa

    2016-01-01

    Measuring the quality of the "product" is elemental in education, and most studies depend on observational data about student achievement factors, focusing overwhelmingly on quantitative data namely achievement scores, school data like attendance, facilities, expenditure class size, etc. But there is little evidence of learner…

  20. The high-order quantum coherence of thermal light

    NASA Astrophysics Data System (ADS)

    Chen, Hui

    Thermal light, such as sunlight, is usually considered classical light. In a macroscopic picture, classical theory successfully explained the first-order coherence phenomena of thermal light. The macroscopic theory, based on the statistical behavior of light intensity fluctuations, however, can only phenomenologically explain the second- or higher-order coherence phenomena of thermal light. This thesis introduces a microscopic quantum picture, based on the interferences of a large number of randomly distributed and randomly radiated subfields, wavepackets or photons, to the study of high-order coherence of thermal light. This thesis concludes that the second-order intensity fluctuation correlation is caused by nonlocal interference: a pair of wavepackets, which are randomly paired together, interferes with the pair itself at two distant space-time coordinates. This study has the following practical motivations: (1) to simulate N-qbits. Practical quantum computing requires quantum bits(qubits) of N-digit to represent all possible integers from 0 to 2N-1 simultaneously. A large number of independent particles can be prepared to represent a large set of N orthogonal |0> and |1> bits. In fact, based on our recent experiments of simulating the high-order correlation of entangled photons, thermal radiation is suggested as a promising source for quantum information processing. (2) to achieve sunlight ghost imaging. Ghost imaging has three attractive non-classical features: (a) the ghost camera can "see" targets that can never be seen by a classic camera; (2) it is turbulence-free; and (3) its spatial resolution is mainly determined by the angular diameter of the light source. For example, a sunlight ghost image of an object on earth may achieve a spatial resolution of 200 micrometer because the angular diameter of sun is 0.53 degree with respect to Earth. Although ghost imaging has been experimental demonstrated by using entangled photon pairs and "pseudo-thermal light

  1. High thermal-transport capacity heat pipes for space radiators

    NASA Technical Reports Server (NTRS)

    Carlson, Albert W.; Gustafson, Eric; Roukis, Susan L.

    1987-01-01

    This paper presents the results of performance tests of several dual-slot heat pipe test articles. The dual-slot configuration has a very high thermal transport capability and has been identified as a very promising candidate for the radiator system for the NASA Space Station solar dynamic power modules. Two six-foot long aluminum heat pipes were built and tested with ammonia and acetone. A 20-ft long heat pipe was also built and tested with ammonia. The test results have been compared with performance predictions. A thermal transport capacity of 2000 W at an adverse tilt of 1 in. and a 1000 W capacity at an adverse tilt of 2 in. were achieved on the 20-ft long heat pipe. These values are in close agreement with the predicted performance limits.

  2. Achievement of Hispanic Students in American High Schools: Background Characteristics and Achievement. Contractor Report.

    ERIC Educational Resources Information Center

    Nielsen, Francois; Fernandez, Roberto M.

    Presenting data and analyses from the first wave of the study "High School and Beyond" (HS&B), a longitudinal study of United States high school sophomores and seniors, the report focuses on the composition of the Hispanic tenth and twelfth grade student population with respect to various characteristics; i.e., language use and proficiency, length…

  3. Development of a high force thermal latch

    NASA Astrophysics Data System (ADS)

    Nygren, William D.

    1995-05-01

    This paper describes the preliminary development of a high force thermal latch (HFTL). The HFTL has one moving part which is restrained in the latched position by a low melting temperature or fusible metal alloy. When heated the fusible alloy flows to a receiving chamber and in so doing at first releases the tension load in the latch bolt and later releases the bolt itself. The HFTL can be used in place of pyrotechnically activated spacecraft release devices in those instances where the elimination of both pyrotechnic shock-loading and rapid strain-energy release take precedence over the near instantaneous release offered by ordnance initiated devices.

  4. Development of a high force thermal latch

    NASA Technical Reports Server (NTRS)

    Nygren, William D.

    1995-01-01

    This paper describes the preliminary development of a high force thermal latch (HFTL). The HFTL has one moving part which is restrained in the latched position by a low melting temperature or fusible metal alloy. When heated the fusible alloy flows to a receiving chamber and in so doing at first releases the tension load in the latch bolt and later releases the bolt itself. The HFTL can be used in place of pyrotechnically activated spacecraft release devices in those instances where the elimination of both pyrotechnic shock-loading and rapid strain-energy release take precedence over the near instantaneous release offered by ordnance initiated devices.

  5. Threatened and Placed at Risk: High Achieving African American Males in Urban High Schools

    ERIC Educational Resources Information Center

    McGee, Ebony O.

    2013-01-01

    This study investigated the risk and protective factors of 11 high-achieving African American males attending 4 urban charter high schools in a Midwestern city to determine what factors account for their resilience and success in mathematics courses, and in high school more generally. This research was guided by a Phenomenological Variant of…

  6. Preferences of High Achieving High School Students in Their Career Development

    ERIC Educational Resources Information Center

    Kim, Mihyeon

    2010-01-01

    The intent of this study was to identify the needs and preference of high-achieving high school students. In terms of career related programs in high school, students listed AP courses and mentoring as their preferred career-related programs. Also, students stated that career guidance by counselors, workshops or sessions, and tech prep were the…

  7. Influence of High Cycle Thermal Loads on Thermal Fatigue Behavior of Thick Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1997-01-01

    Thick thermal barrier coating systems in a diesel engine experience severe thermal Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF) during engine operation. In the present study, the mechanisms of fatigue crack initiation and propagation, as well as of coating failure, under thermal loads which simulate engine conditions, are investigated using a high power CO2 laser. In general, surface vertical cracks initiate early and grow continuously under LCF and HCF cyclic stresses. It is found that in the absence of interfacial oxidation, the failure associated with LCF is closely related to coating sintering and creep at high temperatures, which induce tensile stresses in the coating after cooling. Experiments show that the HCF cycles are very damaging to the coating systems. The combined LCF and HCF tests produced more severe coating surface cracking, microspallation and accelerated crack growth, as compared to the pure LCF test. It is suggested that the HCF component cannot only accelerate the surface crack initiation, but also interact with the LCF by contributing to the crack growth at high temperatures. The increased LCF stress intensity at the crack tip due to the HCF component enhances the subsequent LCF crack growth. Conversely, since a faster HCF crack growth rate will be expected with lower effective compressive stresses in the coating, the LCF cycles also facilitate the HCF crack growth at high temperatures by stress relaxation process. A surface wedging model has been proposed to account for the HCF crack growth in the coating system. This mechanism predicts that HCF damage effect increases with increasing temperature swing, the thermal expansion coefficient and the elastic modulus of the ceramic coating, as well as the HCF interacting depth. A good agreement has been found between the analysis and experimental evidence.

  8. Thermal Conductivity of Argon at High Pressures and High Temperatures

    NASA Astrophysics Data System (ADS)

    Wong, M. L.; Goncharov, A. F.; Dalton, D. A.; Ojwang, J.; Struzhkin, V.; Konopkova, Z.; Lazor, P.

    2010-12-01

    Accurate data on the thermal conductivity of argon at high pressures and high temperatures is essential to unraveling the nature of the Earth’s interior. Argon is a common pressure-transmitting medium in diamond anvil cell (DAC) experiments, which is commonly used for studying the properties of minerals at pressures and temperatures native to the mantel and core. We used a transient heating technique (Beck et al., 2007) in a symmetric DAC up to 50 GPa and 2500 K. A thin iridium foil (1 μm thick) positioned in a recessed gasket hole filled with argon served as a heat absorber (coupler) to pump thermal energy into the sample. We used 6 μs width pulses from electronically modulated Yb-based fiber laser. We determined the temperature of the coupler with 500 ns time resolution by applying the Planck function to its thermal emission spectrum, and doing this over time yields temperature verses time for the coupler. Using finite element (FE) calculation methods we simulated the heat flux transfer in the DAC cavity using the experimentally determined geometric and laser heating parameters. The thermochemical parameters of Ir and Ar were determined by scaling the ambient pressure data using the available equations of state. The temperature dependent thermal conductivity of Ar was determined by fitting the results of FE calculations to the experimentally determined time dependent coupler temperature. We used the results of the theoretical calculations (Tretiakov & Scandolo, 2004) as the initial input. The results for the pressure and temperature dependent thermal conductivity of Ar will be reported at the meeting. This work is supported by NSF EAR 0711358, NSF-REU, Carnegie Institution of Washington, and DOE-NNSA (CDAC). Beck, P; Goncharov, A.F., Struzhkin, V.V., Militzer, B, Mao, H.K, Hemley, R.J. (2007). Measurement of thermal diffusivity at high pressure using a transient heating technique, Appl Phys. Lett. 91, 181914-(1-3). Tretiakov, K. V. & S. Scandolo (2004

  9. Thermal conductance of metal-diamond interfaces at high pressure.

    PubMed

    Hohensee, Gregory T; Wilson, R B; Cahill, David G

    2015-01-01

    The thermal conductance of interfaces between metals and diamond, which has a comparatively high Debye temperature, is often greater than can be accounted for by two-phonon processes. The high pressures achievable in a diamond anvil cell (DAC) can significantly extend the metal phonon density of states to higher frequencies, and can also suppress extrinsic effects by greatly stiffening interface bonding. Here we report time-domain thermoreflectance measurements of metal-diamond interface thermal conductance up to 50 GPa in the DAC for Pb, Au0.95Pd0.05, Pt and Al films deposited on type 1A natural [100] and type 2A synthetic [110] diamond anvils. In all cases, the thermal conductances increase weakly or saturate to similar values at high pressure. Our results suggest that anharmonic conductance at metal-diamond interfaces is controlled by partial transmission processes, where a diamond phonon that inelastically scatters at the interface absorbs or emits a metal phonon. PMID:25744853

  10. High Cycle Thermal Fatigue in French PWR

    SciTech Connect

    Blondet, Eric; Faidy, Claude

    2002-07-01

    Different fatigue-related incidents which occurred in the world on the auxiliary lines of the reactor coolant system (SIS, RHR, CVC) have led EDF to search solutions in order to avoid or to limit consequences of thermodynamic phenomenal (Farley-Tihange, free convection loop and stratification, independent thermal cycling). Studies are performed on mock-up and compared with instrumentation on nuclear power stations. At the present time, studies allow EDF to carry out pipe modifications and to prepare specifications and recommendations for next generation of nuclear power plants. In 1998, a new phenomenal appeared on RHR system in Civaux. A crack was discovered in an area where hot and cold fluids (temperature difference of 140 deg. C) were mixed. Metallurgic studies concluded that this crack was caused by high cycle thermal fatigue. Since 1998, EDF is making an inventory of all mixing areas in French PWR on basis of criteria. For all identified areas, a method was developed to improve the first classifying and to keep back only potential damage pipes. Presently, studies are performing on the charging line nozzle connected to the reactor pressure vessel. In order to evaluate the load history, a mock-up has been developed and mechanical calculations are realised on this nozzle. The paper will make an overview of EDF conclusions on these different points: - dead legs and vortex in a no flow connected line; - stratification; - mixing tees with high {delta}T. (authors)

  11. Thermally Activated Delayed Fluorescence in Polymers: A New Route toward Highly Efficient Solution Processable OLEDs.

    PubMed

    Nikolaenko, Andrey E; Cass, Michael; Bourcet, Florence; Mohamad, David; Roberts, Matthew

    2015-11-25

    Efficient intermonomer thermally activated delayed fluorescence is demonstrated for the first time, opening a new route to achieving high-efficiency solution processable polymer light-emitting device materials. External quantum efficiency (EQE) of up to 10% is achieved in a simple fully solution-processed device structure, and routes for further EQE improvement identified. PMID:26457683

  12. The Effect of Music Participation on Mathematical Achievement and Overall Academic Achievement of High School Students

    ERIC Educational Resources Information Center

    Cox, H. A.; Stephens, L. J.

    2006-01-01

    A study was conducted on high school students, comparing those with some music credits to those with none. No statistically significant difference was found in their mean math grade point averages (GPA) or their mean cumulative GPAs. Students were then separated into two groups based on the number of music credits. Students who had earned at least…

  13. Academic attainment and the high school science experiences among high-achieving African American males

    NASA Astrophysics Data System (ADS)

    Trice, Rodney Nathaniel

    This study examines the educational experiences of high achieving African American males. More specifically, it analyzes the influences on their successful navigation through high school science. Through a series of interviews, observations, questionnaires, science portfolios, and review of existing data the researcher attempted to obtain a deeper understanding of high achieving African American males and their limitations to academic attainment and high school science experiences. The investigation is limited to ten high achieving African American male science students at Woodcrest High School. Woodcrest is situated at the cross section of a suburban and rural community located in the southeastern section of the United States. Although this investigation involves African American males, all of whom are successful in school, its findings should not be generalized to this nor any other group of students. The research question that guided this study is: What are the limitations to academic attainment and the high school science experiences of high achieving African American males? The student participants expose how suspension and expulsion, special education placement, academic tracking, science instruction, and teacher expectation influence academic achievement. The role parents play, student self-concept, peer relationships, and student learning styles are also analyzed. The anthology of data rendered three overarching themes: (1) unequal access to education, (2) maintenance of unfair educational structures, and (3) authentic characterizations of African American males. Often the policies and practices set in place by school officials aid in creating hurdles to academic achievement. These policies and practices are often formed without meaningful consideration of the unintended consequences that may affect different student populations, particularly the most vulnerable. The findings from this study expose that high achieving African American males face major

  14. High Temperature Aerogels for Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Mbah, Godfrey C.

    2008-01-01

    High temperature aerogels in the Al2O3-SiO2 system are being investigated as possible constituents for lightweight integrated thermal protection system (TPS) designs for use in supersonic and hypersonic applications. Gels are synthesized from ethoxysilanes and AlCl3.6H2O, using an epoxide catalyst. The influence of Al:Si ratio, solvent, water to metal and water to alcohol ratios on aerogel composition, morphology, surface area, and pore size distribution were examined, and phase transformation on heat treatment characterized. Aerogels have been fabricated which maintain porous, fractal structures after brief exposures to 1000 C. Incorporation of nanofibers, infiltration of aerogels into SiC foams, use of polymers for crosslinking the aerogels, or combinations of these, offer potential for toughening and integration of TPS with composite structure. Woven fabric composites having Al2O3-SiO2 aerogels as a matrix also have been fabricated. Continuing work is focused on reduction in shrinkage and optimization of thermal and physical properties.

  15. Parenting Style, Perfectionism, and Creativity in High-Ability and High-Achieving Young Adults

    ERIC Educational Resources Information Center

    Miller, Angie L.; Lambert, Amber D.; Speirs Neumeister, Kristie L.

    2012-01-01

    The current study explores the potential relationships among perceived parenting style, perfectionism, and creativity in a high-ability and high-achieving young adult population. Using data from 323 honors college students at a Midwestern university, bivariate correlations suggested positive relationships between (a) permissive parenting style and…

  16. Success Despite Socioeconomics: A Case Study of a High-Achieving, High-Poverty School

    ERIC Educational Resources Information Center

    Tilley, Thomas Brent; Smith, Samuel J.; Claxton, Russell L.

    2012-01-01

    This case study of a high-achieving, high-poverty school describes the school's leadership, culture, and programs that contributed to its success. Data were collected from two surveys (the School Culture Survey and the Vanderbilt Assessment of Leadership in Education), observations at the school site, and interviews with school personnel. The…

  17. "Brains before "Beauty"?" High Achieving Girls, School and Gender Identities

    ERIC Educational Resources Information Center

    Skelton, Christine; Francis, Becky; Read, Barbara

    2010-01-01

    In recent years educational policy on gender and achievement has concentrated on boys' underachievement, frequently comparing it with the academic success of girls. This has encouraged a perception of girls as the "winners" of the educational stakes and assumes that they no longer experience the kinds of gender inequalities identified in earlier…

  18. Cooperative Learning: A Standard for High Achievement. The Nutshell Series.

    ERIC Educational Resources Information Center

    Williams, R. Bruce

    2007-01-01

    This book reveals some of the structural complexities involved in implementing authentic cooperative learning in the classroom. It also suggests that when full cooperative learning structures are implemented, the benefits in student achievement often can be astounding. Descriptions, decisions, designs, and developments, a simple four-part scheme,…

  19. Dominant Achievement Goals across Tracks in High School

    ERIC Educational Resources Information Center

    Scheltinga, Peter A. M.; Kuyper, Hans; Timmermans, Anneke C.; van der Werf, Greetje P. C.

    2016-01-01

    The dominant achievement goals (DAGs) of 7,008 students in the third grade of Dutch secondary education (US grade 9) were investigated, based on Elliot & McGregors' 2 × 2 framework (2001), in relation to track-level and motivational variables. We found the mastery-approach goal and the performance-approach goal, generally considered adaptive,…

  20. Optical Diagnostics for High-Temperature Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.

    2009-01-01

    Thermal barrier coatings (TBCs) are typically composed of translucent ceramic oxides that provide thermal protection for metallic components exposed to high-temperature environments, such as in jet turbine engines. Taking advantage of the translucent nature of TBCs, optical diagnostics have been developed that can provide an informed assessment of TBC health that will allow mitigating action to be taken before TBC degradation threatens performance or safety. In particular, rare-earth-doped luminescent sublayers have been integrated into the TBC structure to produce luminescence that monitors TBC erosion, delamination, and temperature gradients. Erosion monitoring of TBC-coated specimens is demonstrated by utilizing visible luminescence that is excited from a sublayer that is exposed by erosion. TBC delamination monitoring is achieved in TBCs with a base rare-earth-doped luminescent sublayer by the reflectance-enhanced increase in luminescence produced in regions containing buried delamination cracks. TBC temperature monitoring is demonstrated using the temperature-dependent decay time for luminescence originating from the specific coating depth associated with a rare-earth-doped luminescent sublayer. The design and implementation of these TBCs with integrated luminescent sublayers is discussed, including co-doping strategies to produce more penetrating near-infrared luminescence. It is demonstrated that integration of the rare-earth-doped sublayers is achieved with no reduction in TBC life. In addition, results for multilayer TBCs designed to also perform as radiation barriers are also presented.

  1. The Relationship between Self-Esteem and Academic Achievement in a Group of High, Medium, and Low Secondary Public High School Achievers.

    ERIC Educational Resources Information Center

    Thomas-Brantley, Betty J.

    This study investigated the relationship between self-esteem and academic achievement in a group of 150 high, medium, and low achievers at a large midwestern public high school. Correlating data from the Coopersmith Inventory of self-esteem with grades, cumulative grade point averages, and class rank, the study disclosed a positive correlation…

  2. Thermal Conductance Engineering for High-Speed TES Microcalorimeters

    NASA Astrophysics Data System (ADS)

    Hays-Wehle, J. P.; Schmidt, D. R.; Ullom, J. N.; Swetz, D. S.

    2016-07-01

    Many current and future applications for superconducting transition-edge sensor (TES) microcalorimeters require significantly faster pulse response than is currently available. X-ray spectroscopy experiments at next-generation synchrotron light sources need to successfully capture very large fluxes of photons, while detectors at free-electron laser facilities need pulse response fast enough to match repetition rates of the source. Additionally, neutrino endpoint experiments such as HOLMES need enormous statistics, yet are extremely sensitive to pile-up effects that can distort spectra. These issues can be mitigated only by fast rising and falling edges. To address these needs, we have designed high-speed TES detectors with novel geometric enhancements to increase the thermal conductance of pixels suspended on silicon nitride membranes. This paper shows that the thermal conductivity can be precisely engineered to values spanning over an order of magnitude to achieve fast thermal relaxation times tailored to the relevant applications. Using these pixel prototypes, we demonstrate decay time constants faster than 100 μ s, while still maintaining spectral resolution of 3 eV FWHM at 1.5 keV. This paper also discusses the trade-offs inherent in reducing the pixel time constant, such as increased bias current leading to degradation in energy resolution, and potential modifications to improve performance.

  3. Thermal Conductance Engineering for High-Speed TES Microcalorimeters

    NASA Astrophysics Data System (ADS)

    Hays-Wehle, J. P.; Schmidt, D. R.; Ullom, J. N.; Swetz, D. S.

    2016-01-01

    Many current and future applications for superconducting transition-edge sensor (TES) microcalorimeters require significantly faster pulse response than is currently available. X-ray spectroscopy experiments at next-generation synchrotron light sources need to successfully capture very large fluxes of photons, while detectors at free-electron laser facilities need pulse response fast enough to match repetition rates of the source. Additionally, neutrino endpoint experiments such as HOLMES need enormous statistics, yet are extremely sensitive to pile-up effects that can distort spectra. These issues can be mitigated only by fast rising and falling edges. To address these needs, we have designed high-speed TES detectors with novel geometric enhancements to increase the thermal conductance of pixels suspended on silicon nitride membranes. This paper shows that the thermal conductivity can be precisely engineered to values spanning over an order of magnitude to achieve fast thermal relaxation times tailored to the relevant applications. Using these pixel prototypes, we demonstrate decay time constants faster than 100 μ s, while still maintaining spectral resolution of 3 eV FWHM at 1.5 keV. This paper also discusses the trade-offs inherent in reducing the pixel time constant, such as increased bias current leading to degradation in energy resolution, and potential modifications to improve performance.

  4. High thermal conductivity of hexagonal boron nitride laminates

    NASA Astrophysics Data System (ADS)

    Zheng, Jin-Cheng; Zhang, Liang; Kretinin, A. V.; Morozov, S. V.; Wang, Yi Bo; Wang, Tun; Li, Xiaojun; Ren, Fei; Zhang, Jingyu; Lu, Ching-Yu; Chen, Jia-Cing; Lu, Miao; Wang, Hui-Qiong; Geim, A. K.; Novoselov, K. S.

    2016-03-01

    Two-dimensional materials are characterised by a number of unique physical properties which can potentially make them useful to a wide diversity of applications. In particular, the large thermal conductivity of graphene and hexagonal boron nitride (hBN) has already been acknowledged and these materials have been suggested as novel core materials for thermal management in electronics. However, it was not clear if mass produced flakes of hBN would allow one to achieve an industrially-relevant value of thermal conductivity. Here we demonstrate that laminates of hBN exhibit thermal conductivity of up to 20 W/m·K, which is significantly larger than that currently used in thermal management. We also show that the thermal conductivity of laminates increases with the increasing volumetric mass density, which creates a way of fine tuning its thermal properties.

  5. Examining Organizational Practices That Predict Persistence among High-Achieving Black Males in High School

    ERIC Educational Resources Information Center

    Anderson, Kenneth Alonzo

    2016-01-01

    Background/Context: This article summarizes an increasing trend of antideficit Black male research in mathematics and highlights opportunities to add to the research. A review of the literature shows that antideficit researchers often examine relationships between individual traits and persistence of high-achieving Black males in mathematics.…

  6. Relationships among Stress, Coping, and Mental Health in High-Achieving High School Students

    ERIC Educational Resources Information Center

    Suldo, Shannon M.; Shaunessy, Elizabeth; Hardesty, Robin

    2008-01-01

    This study investigates the relationships among stress, coping, and mental health in 139 students participating in an International Baccalaureate (IB) high school diploma program. Mental health was assessed using both positive indicators (life satisfaction, academic achievement, academic self-efficacy) and negative indicators (psychopathology) of…

  7. The Strengths of High-Achieving Black High School Students in a Racially Diverse Setting

    ERIC Educational Resources Information Center

    Marsh, Kris; Chaney, Cassandra; Jones, Derrick

    2012-01-01

    Robert Hill (1972) identified strengths of Black families: strong kinship bonds, strong work orientation, adaptability of family roles, high achievement orientation, and religious orientation. Some suggest these strengths sustain the physical, emotional, social, and spiritual needs of Blacks. This study used narratives and survey data from a…

  8. Process gases for high velocity oxy-fuel thermal spraying

    SciTech Connect

    Creffield, G.K.; Chapman, I.F.; Cole, M.A.; Page, W.J.; McDonough, T.

    1994-12-31

    The importance of fuel and other process gases for high velocity oxy-fuel (HVOF) thermal spraying and especially the delivery of them to the point of use is well recognized. Problems associated with the supply of liquid fuel gases, at the high flow rates and pressures required by this process, have been addressed. Considerable development work has gone into designing an appropriate liquid withdrawal and vaporizer system for propylene, which overcomes these previous difficulties and enables users to maintain adequate fuel gas flow rates in order to ensure optimum operating conditions for the production of high quality coatings. A feature of the thermal spray process is that the temperature of the workpiece is kept low, typically below 150 C, in order to reduce residual stresses in the coating and to protect heat sensitive substrates. Traditionally this has been by compressed air, however, improved cooling has been achieved using carbon dioxide. Specially designed equipment is now available which provides and directs a cold mixture of carbon dioxide gas and solid particles (snow) via suitable nozzles, on the workpiece. The position of the cooling stream can be varied, depending on the application. These developments emphasize the importance now attached to providing dedicated gas installation packages for HVOF.

  9. Relationship between High School Mathematical Achievement and Quantitative GPA

    ERIC Educational Resources Information Center

    Brown, Jennifer L.; Halpin, Glennelle; Halpin, Gerald

    2015-01-01

    The demand for STEM graduates has increased, but the number of incoming freshmen who declare a STEM major has remained stagnant. High school courses, such as calculus, can open or close the gate for students interested in careers in STEM. The purpose of this study was to determine if high school mathematics preparation was a significant…

  10. Ultra low thermal expansion, highly thermal shock resistant ceramic

    DOEpatents

    Limaye, Santosh Y.

    1996-01-01

    Three families of ceramic compositions having the given formula: .phi..sub.1+X Zr.sub.4 P.sub.6-2X Si.sub.2X O.sub.24, .phi..sub.1+X Zr.sub.4-2X Y.sub.2X P.sub.6 O.sub.24 and .phi..sub.1+X Zr.sub.4-X Y.sub.X P.sub.6-2X Si.sub.X O.sub.24 wherein .phi. is either Strontium or Barium and X has a value from about 0.2 to about 0.8 have been disclosed. Ceramics formed from these compositions exhibit very low, generally near neutral, thermal expansion over a wide range of elevated temperatures.

  11. Ultra low thermal expansion, highly thermal shock resistant ceramic

    DOEpatents

    Limaye, S.Y.

    1996-01-30

    Three families of ceramic compositions having the given formula: {phi}{sub 1+X}Zr{sub 4}P{sub 6{minus}2X}Si{sub 2X}O{sub 24}, {phi}{sub 1+X}Zr{sub 4{minus}2X}Y{sub 2X}P{sub 6}O{sub 24} and {phi}{sub 1+X}Zr{sub 4{minus}X}Y{sub X}P{sub 6{minus}2X}Si{sub X}O{sub 24} wherein {phi} is either strontium or barium and X has a value from about 0.2 to about 0.8 have been disclosed. Ceramics formed from these compositions exhibit very low, generally near neutral, thermal expansion over a wide range of elevated temperatures. 7 figs.

  12. Practically Perfect in Every Way: Can Reframing Perfectionism for High-Achieving Undergraduates Impact Academic Resilience?

    ERIC Educational Resources Information Center

    Dickinson, Mary J.; Dickinson, David A. G.

    2015-01-01

    This study focuses on a pan-disciplinary scheme that targeted high-achieving undergraduate students. Earlier research from the scheme argued that high achievers have discernibly different learning and personal development support needs. One of the most frequent self-reported challenges within this high-achieving group is perfectionism. This…

  13. The Relationship to Achievement on the California High School Exit Exam for Language Minority Students.

    ERIC Educational Resources Information Center

    Garcia, Paul A.; Gopal, Malati

    2003-01-01

    Examines first year results of the California High School Exit Exam (CAHSEE) required for students to earn a high school diploma. Results suggest this high stakes test failed to meet legislative objectives to increase achievement and close the achievement gap. Instead, language-minority students with passing scores achieved significantly below…

  14. Achieving thermography with a thermal security camera using uncooled amorphous silicon microbolometer image sensors

    NASA Astrophysics Data System (ADS)

    Wang, Yu-Wei; Tesdahl, Curtis; Owens, Jim; Dorn, David

    2012-06-01

    Advancements in uncooled microbolometer technology over the last several years have opened up many commercial applications which had been previously cost prohibitive. Thermal technology is no longer limited to the military and government market segments. One type of thermal sensor with low NETD which is available in the commercial market segment is the uncooled amorphous silicon (α-Si) microbolometer image sensor. Typical thermal security cameras focus on providing the best image quality by auto tonemaping (contrast enhancing) the image, which provides the best contrast depending on the temperature range of the scene. While this may provide enough information to detect objects and activities, there are further benefits of being able to estimate the actual object temperatures in a scene. This thermographic ability can provide functionality beyond typical security cameras by being able to monitor processes. Example applications of thermography[2] with thermal camera include: monitoring electrical circuits, industrial machinery, building thermal leaks, oil/gas pipelines, power substations, etc...[3][5] This paper discusses the methodology of estimating object temperatures by characterizing/calibrating different components inside a thermal camera utilizing an uncooled amorphous silicon microbolometer image sensor. Plots of system performance across camera operating temperatures will be shown.

  15. Gender, Student Motivation and Academic Achievement in a Midsized Wisconsin High School

    ERIC Educational Resources Information Center

    Lutzke, Steven Ronald

    2013-01-01

    This mixed-methods study investigated relationships among gender, academic motivation and achievement in a mid-sized Wisconsin high school. A questionnaire was developed that focused on perceived ability, achievement motives and achievement goals. Interviews with teachers focused on relationships among academic motivation and gender achievement.…

  16. Advanced Liquid-Cooling Garment Using Highly Thermally Conductive Sheets

    NASA Technical Reports Server (NTRS)

    Ruemmele, Warren P.; Bue, Grant C.; Orndoff, Evelyne; Tang, Henry

    2010-01-01

    This design of the liquid-cooling garment for NASA spacesuits allows the suit to remove metabolic heat from the human body more effectively, thereby increasing comfort and performance while reducing system mass. The garment is also more flexible, with fewer restrictions on body motion, and more effectively transfers thermal energy from the crewmember s body to the external cooling unit. This improves the garment s performance in terms of the maximum environment temperature in which it can keep a crewmember comfortable. The garment uses flexible, highly thermally conductive sheet material (such as graphite), coupled with cooling water lines of improved thermal conductivity to transfer the thermal energy from the body to the liquid cooling lines more effectively. The conductive sheets can be layered differently, depending upon the heat loads, in order to provide flexibility, exceptional in-plane heat transfer, and good through-plane heat transfer. A metal foil, most likely aluminum, can be put between the graphite sheets and the external heat source/sink in order to both maximize through-plane heat transfer at the contact points, and to serve as a protection to the highly conductive sheets. Use of a wicking layer draws excess sweat away from the crewmember s skin and the use of an outer elastic fabric ensures good thermal contact of the highly conductive underlayers with the skin. This allows the current state of the art to be improved by having cooling lines that can be more widely spaced to improve suit flexibility and to reduce weight. Also, cooling liquid does not have to be as cold to achieve the same level of cooling. Specific areas on the human body can easily be targeted for greater or lesser cooling to match human physiology, a warmer external environment can be tolerated, and spatial uniformity of the cooling garment can be improved to reduce vasoconstriction limits. Elements of this innovation can be applied to other embodiments to provide effective heat

  17. Achieving high CRI from warm to super white

    NASA Astrophysics Data System (ADS)

    Bailey, Edward; Tormey, Ellen S.

    2007-09-01

    Light sources which produce a high color rendering index (CRI) have many applications in the lighting industry today. High color rendering accents the rich color which abounds in nature, interior design, theatrical costumes and props, clothing and fabric, jewelry, and machine vision applications. Multi-wavelength LED sources can pump phosphors at multiple stokes shift emission regimes and when combined with selected direct emission sources can allow for greater flexibility in the production of warm-white and cool white light of specialty interest. Unique solutions to R8 and R14 CRI >95 at 2850K, 4750K, 5250K, and 6750K presented.

  18. Impact of learning orientation on African American children's attitudes toward high-achieving peers.

    PubMed

    Marryshow, Derrick; Hurley, Eric A; Allen, Brenda A; Tyler, Kenneth M; Boykin, A Wade

    2005-01-01

    This study examined Ogbu's widely accepted thesis that African American students reject high academic achievement because they perceive its limited utility in a world where their upward mobility is constrained by racial discrimination. Boykin's psychosocial integrity model contends that Black students value high achievement but that discrepancies between their formative cultural experiences and those imposed in school lead them to reject the modes of achievement available in classrooms. Ninety Black children completed a measure of attitudes toward students who achieve via mainstream or African American cultural values. Participants rejected the mainstream achievers and embraced the African American cultural achievers. Moreover, they expected their teachers to embrace the mainstream achievers and reject those who achieved through high-verve behavior. Results suggest that Boykin's thesis is a needed refinement to Ogbu's ideas. They indicate that Black children may reject not high achievement but some of the mainstream cultural values and behaviors on which success in mainstream classrooms is made contingent. PMID:16402748

  19. Technology's Achilles Heel: Achieving High-Quality Implementation

    ERIC Educational Resources Information Center

    Hall, Gene E.

    2010-01-01

    An inherent characteristic of technology education is the continual development of new technologies and creating innovative applications of already existing technologies. As exciting as these innovations can be, technology educators and school staffs are frequently challenged to accomplish high levels of implementation. The metaphor of the…

  20. Vocational Interests of Intellectually Gifted and Highly Achieving Young Adults

    ERIC Educational Resources Information Center

    Vock, Miriam; Koller, Olaf; Nagy, Gabriel

    2013-01-01

    Background: Vocational interests play a central role in the vocational decision-making process and are decisive for the later job satisfaction and vocational success. Based on Ackerman's (1996) notion of "trait complexes," specific interest profiles of gifted high-school graduates can be expected. Aims: Vocational interests of gifted and highly…

  1. Academic Dishonesty among Gifted and High-Achieving Students

    ERIC Educational Resources Information Center

    Geddes, Kimberly A.

    2011-01-01

    Gifted high school students are essentially absent in the research concerning academic integrity; however, over the past few years, educators of gifted students have noticed an increase in the occurrences of academic dishonesty among students in gifted classrooms (Abilock, 2009). This research may be analyzed to provide some insight into the…

  2. Student Achievement Data Systems in High and Low Performing Schools

    ERIC Educational Resources Information Center

    Stachowiak, Jeannie E.

    2013-01-01

    The purpose of this study was to determine if there was a difference in how high and low performing elementary school districts use and analyze data to differentiate instruction, make changes to district/grade level curriculum, determine professional development needs, determine teacher effectiveness, and determine the use of school district…

  3. Community Schools Seek to Improve High School Achievement, College Readiness

    ERIC Educational Resources Information Center

    Gilroy, Marilyn

    2011-01-01

    The Coalition for Community Schools, an alliance of more than 150 national, state, and local organizations, is bringing public schools in partnership with community resources to improve student success. While that might seem like an abstract idea, it has very concrete goals, such as boosting high school graduation rates and college readiness.…

  4. Scientific Reasoning and Achievement in a High School English Course.

    ERIC Educational Resources Information Center

    Kral, E. A.

    1997-01-01

    A Piagetian-based, systematic instructional theory developed by A. E. Lawson was used as a reasoning model in a 12th-grade English course at Grand Island Senior High in Grand Island, Nebraska, from 1982 to 1991. The thinking patterns that comprised the hypothetical-deductive stage of human intellectual development used in the course were…

  5. Common Core and America's High-Achieving Students

    ERIC Educational Resources Information Center

    Plucker, Jonathan A.

    2015-01-01

    While the merit and politics of the Common Core State Standards (CCSS) have been much debated and discussed, one topic has been virtually ignored: What do the standards portend for America's high-ability students? This brief addresses that question and provides guidance for CCSS-implementing districts and schools as they seek to help these…

  6. Achieving High Performance with FPGA-Based Computing

    PubMed Central

    Herbordt, Martin C.; VanCourt, Tom; Gu, Yongfeng; Sukhwani, Bharat; Conti, Al; Model, Josh; DiSabello, Doug

    2011-01-01

    Numerous application areas, including bioinformatics and computational biology, demand increasing amounts of processing capability. In many cases, the computation cores and data types are suited to field-programmable gate arrays. The challenge is identifying the design techniques that can extract high performance potential from the FPGA fabric. PMID:21603088

  7. Organizational Citizenship of Faculty and Achievement of High School Students

    ERIC Educational Resources Information Center

    DiPaola, Michael F.; Hoy, Wayne K.

    2005-01-01

    All successful organizations, including successful high schools, have employees who go beyond their formal job responsibilities and freely give of their time and energy to succeed. Organ was the first to use the phrase "organizational citizenship behavior" (OCB) to denote organizationally beneficial behavior of workers that was not prescribed but…

  8. High-Achieving Schools Put Equity Front and Center

    ERIC Educational Resources Information Center

    Gleason, Sonia Caus; Gerzon, Nancy

    2014-01-01

    How does professional learning look and feel in high-poverty schools where every student makes at least one year's worth of progress every year? How do schools and leaders put all the varied components of professional learning together so that they support all students learning every day? What professional learning grounds and sustains…

  9. High temperature dependence of thermal transport in graphene foam.

    PubMed

    Li, Man; Sun, Yi; Xiao, Huying; Hu, Xuejiao; Yue, Yanan

    2015-03-13

    In contrast to the decreased thermal property of carbon materials with temperature according to the Umklapp phonon scattering theory, highly porous free-standing graphene foam (GF) exhibits an abnormal characteristic that its thermal property increases with temperature above room temperature. In this work, the temperature dependence of thermal properties of free-standing GF is investigated by using the transient electro-thermal technique. Significant increase for thermal conductivity and thermal diffusivity from ∼0.3 to 1.5 W m(-1) K(-1) and ∼4 × 10(-5) to ∼2 × 10(-4) m(2) s(-1) respectively is observed with temperature from 310 K to 440 K for three GF samples. The quantitative analysis based on a physical model for porous media of Schuetz confirms that the thermal conductance across graphene contacts rather than the heat conductance inside graphene dominates thermal transport of our GFs. The thermal expansion effect at an elevated temperature makes the highly porous structure much tighter is responsible for the reduction in thermal contact resistance. Besides, the radiation heat exchange inside the pores of GFs improves the thermal transport at high temperatures. Since free-standing GF has great potential for being used as supercapacitor and battery electrode where the working temperature is always above room temperature, this finding is beneficial for thermal design of GF-based energy applications. PMID:25683178

  10. High-resolution and high-conductive electrode fabrication on a low thermal resistance flexible substrate

    NASA Astrophysics Data System (ADS)

    Kang, Bongchul; Kno, Jinsung; Yang, Minyang

    2011-07-01

    Processes based on the liquid-state pattern transfer, like inkjet printing, have critical limitations including low resolution and low electrical conductivity when fabricating electrodes on low thermal resistance flexible substrates such as polyethylene terephthalate (PET). Those are due to the nonlinear transfer mechanism and the limit of the sintering temperature. Although the laser direct curing (LDC) of metallic inks is an alternative process to improve the resolution, it is also associated with the disadvantages of causing thermal damage to the polymer substrate. This paper suggests the laser induced pattern adhesion transfer method to fabricate electrodes of both high electrical conductivity and high resolution on a PET substrate. First, solid patterns are cost-effectively created by the LDC of the organometallic silver ink on a glass that is optically and thermally stable. The solid patterns sintered on the glass are transferred to the PET substrate by the photo-thermally generated adhesion force of the substrate. Therefore, we achieved electrodes with a minimum line width of 10 µm and a specific resistance of 3.6 μΩcm on the PET substrate. The patterns also showed high mechanical reliability.

  11. ArF processing of 90-nm design rule lithography achieved through enhanced thermal processing

    NASA Astrophysics Data System (ADS)

    Kagerer, Markus; Miller, Daniel; Chang, Wayne; Williams, Daniel J.

    2006-03-01

    As the lithography community has moved to ArF processing on 300 mm wafers for 90 nm design rules the process characterization of the components of variance continues to highlight the thermal requirements for the post exposure bake (PEB) processing step. In particular as the thermal systems have become increasingly uniform, the transient behavior of the thermal processing system has received the focus of attention. This paper demonstrates how a newly designed and patented thermal processing system was optimized for delivering improved thermal uniformity during a typical 90 second PEB processing cycle, rather than being optimized for steady state performance. This was accomplished with the aid of a wireless temperature measurement wafer system for obtaining real time temperature data and by using a response surface model (RSM) experimental design for optimizing parameters of the temperature controller of the thermal processing system. The new units were field retrofitted seamlessly in <2 days at customer sites without disruption to process recipes or flows. After evaluating certain resist parameters such as PEB temperature sensitivity and post exposure delay (PED) - stability of the baseline process, the new units were benchmarked against the previous PEB plates by processing a split lot experiment. Additional hardware characterization included environmental factors such as air velocity in the vicinity of the PEB plates and transient time between PEB and chill plate. At the completion of the optimization process, the within wafer CD uniformity displayed a significant improvement when compared to the previous hardware. The demonstrated within wafer CD uniformity improved by 27% compared to the initial hardware and baseline process. ITRS requirements for the 90 nm node were exceeded.

  12. High conductance thermal interface concept for space applications

    NASA Technical Reports Server (NTRS)

    Poulin, Elizabeth C.; Horan, D. C.

    1991-01-01

    An interface concept has been developed which produces high conductance at a thermal/mechanical joint without resorting to high clamping forces or potentially contaminating fillers such as thermal grease. This paper discusses the characteristics of several variations of the high conductance interface concept and compares them to those of existing interface concepts proposed for several Space Station applications. The application of the high conductance concept to thermal joints such as internal coldplate interfaces and external equipment module to heat acquisition plate interfaces would reduce the weight and complexity and increase the efficiency of the Space Station Thermal Management System.

  13. Principals’ Perception of Influence on Factors Affecting Student Achievement in Low- and High-Achieving Urban High Schools

    ERIC Educational Resources Information Center

    Bloom, Collette M.; Owens, Emiel W.

    2013-01-01

    The purpose of the study was to compare and contrast influences principals have on staffing, curriculum issues, and discipline policies in high- and low-performing urban high schools. The data for the present study were drawn from the first year follow up of the Educational Longitudinal Survey of 2002-2004 (ELS: 02), administered by the National…

  14. Achieving High Reliability Operations Through Multi-Program Integration

    SciTech Connect

    Holly M. Ashley; Ronald K. Farris; Robert E. Richards

    2009-04-01

    Over the last 20 years the Idaho National Laboratory (INL) has adopted a number of operations and safety-related programs which has each periodically taken its turn in the limelight. As new programs have come along there has been natural competition for resources, focus and commitment. In the last few years, the INL has made real progress in integrating all these programs and are starting to realize important synergies. Contributing to this integration are both collaborative individuals and an emerging shared vision and goal of the INL fully maturing in its high reliability operations. This goal is so powerful because the concept of high reliability operations (and the resulting organizations) is a masterful amalgam and orchestrator of the best of all the participating programs (i.e. conduct of operations, behavior based safety, human performance, voluntary protection, quality assurance, and integrated safety management). This paper is a brief recounting of the lessons learned, thus far, at the INL in bringing previously competing programs into harmony under the goal (umbrella) of seeking to perform regularly as a high reliability organization. In addition to a brief diagram-illustrated historical review, the authors will share the INL’s primary successes (things already effectively stopped or started) and the gaps yet to be bridged.

  15. Telescoping Solar Array Concept for Achieving High Packaging Efficiency

    NASA Technical Reports Server (NTRS)

    Mikulas, Martin; Pappa, Richard; Warren, Jay; Rose, Geoff

    2015-01-01

    Lightweight, high-efficiency solar arrays are required for future deep space missions using high-power Solar Electric Propulsion (SEP). Structural performance metrics for state-of-the art 30-50 kW flexible blanket arrays recently demonstrated in ground tests are approximately 40 kW/cu m packaging efficiency, 150 W/kg specific power, 0.1 Hz deployed stiffness, and 0.2 g deployed strength. Much larger arrays with up to a megawatt or more of power and improved packaging and specific power are of interest to mission planners for minimizing launch and life cycle costs of Mars exploration. A new concept referred to as the Compact Telescoping Array (CTA) with 60 kW/cu m packaging efficiency at 1 MW of power is described herein. Performance metrics as a function of array size and corresponding power level are derived analytically and validated by finite element analysis. Feasible CTA packaging and deployment approaches are also described. The CTA was developed, in part, to serve as a NASA reference solar array concept against which other proposed designs of 50-1000 kW arrays for future high-power SEP missions could be compared.

  16. Efforts toward achieving an unmanned, high-altitude LTA platform

    SciTech Connect

    Onda, Masahiko; Ford, M.L.

    1996-10-01

    The modern demands for an unmanned aerospace platform, capable of long-duration stationkeeping at high-altitudes, are well-known. Satellites, balloons, and aircraft have traditionally served in the role of platform, facilitating tasks ranging from telecommunications to deep-space astronomy. However, limitations on the performance and flexibility of these systems, as well as the intrinsically high-cost of satellite construction, operation, and repair, warrants development of a supplemental technology for the platform. Much has been written in the literature on the possible advantages of a lighter-than-air (LTA) platform, if such an LTA could be constructed. Potential applications include remote sensing, environmental monitoring, mobile communications, space and polar observations, cargo delivery, military reconnaissance, and others. At present, conventional LTA`s are not capable of serving in the manner specified. Within this context, a research program known as HALROP (High Altitude Long Range Observational Platform) is currently underway. The goal is to create a stratospheric platform, possibly in the form of a next generation LTA vehicle. The authors present a qualitative review of their efforts, focusing on milestones in the HALROP Program. 12 refs., 6 figs., 2 tabs.

  17. Resilient thermal barrier for high temperatures

    NASA Technical Reports Server (NTRS)

    Frye, J. A.

    1977-01-01

    Abrasion-resistant thermal barrier, consisting of two layers of woven fabric or braided sleeving with bulk insulation sandwiched between, shows excellent resilience even after compression at temperatures above 980C.

  18. Thermal stress in high temperature cylindrical fasteners

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    1988-01-01

    Uninsulated structures fabricated from carbon or silicon-based materials, which are allowed to become hot during flight, are attractive for the design of some components of hypersonic vehicles. They have the potential to reduce weight and increase vehicle efficiency. Because of manufacturing contraints, these structures will consist of parts which must be fastened together. The thermal expansion mismatch between conventional metal fasteners and carbon or silicon-based structural materials may make it difficult to design a structural joint which is tight over the operational temperature range without exceeding allowable stress limits. In this study, algebraic, closed-form solutions for calculating the thermal stresses resulting from radial thermal expansion mismatch around a cylindrical fastener are developed. These solutions permit a designer to quickly evaluate many combinations of materials for the fastener and the structure. Using the algebraic equations developed, material properties and joint geometry were varied to determine their effect on thermal stresses. Finite element analyses were used to verify that the closed-form solutions derived give the correct thermal stress distribution around a cylindrical fastener and to investigate the effect of some of the simplifying assumptions made in developing the closed-form solutions for thermal stresses.

  19. Achieving high data reduction with integral cubic B-splines

    NASA Technical Reports Server (NTRS)

    Chou, Jin J.

    1993-01-01

    During geometry processing, tangent directions at the data points are frequently readily available from the computation process that generates the points. It is desirable to utilize this information to improve the accuracy of curve fitting and to improve data reduction. This paper presents a curve fitting method which utilizes both position and tangent direction data. This method produces G(exp 1) non-rational B-spline curves. From the examples, the method demonstrates very good data reduction rates while maintaining high accuracy in both position and tangent direction.

  20. High Achievement in Mathematics Education in India: A Report from Mumbai

    ERIC Educational Resources Information Center

    Raman, Manya

    2010-01-01

    This paper reports a study aimed at characterizing the conditions that lead to high achievement in mathematics in India. The study involved eight schools in the greater Mumbai region. The main result of the study is that the notion of high achievement itself is problematic, as reflected in the reports about mathematics achievement within and…

  1. The Relationship between Parental Involvement and Student Achievement in a Rural Florida High School

    ERIC Educational Resources Information Center

    Jackson, Willie A.

    2011-01-01

    Parental involvement is viewed as critical to the development of effective schools and student achievement. The relationship between parental involvement and achievement test scores at a rural high school in Florida was not known. This high school has not met the state standards as determined by the Florida Comprehensive Achievement Test (FCAT)…

  2. Thermal Signatures of Plasmonic Fano Interferences: Toward the Achievement of Nanolocalized Temperature Manipulation.

    PubMed

    Baldwin, Christopher L; Bigelow, Nicholas W; Masiello, David J

    2014-04-17

    A consequence of thermal diffusion is that heat, even when applied to a localized region of space, has the tendency to produce a temperature change that is spatially uniform throughout a material with a thermal conductivity that is much larger than that of its environment. This implies that the degree of spatial correlation between the heat power supplied and the temperature change that it induces is likely to be small. Here, we show, via theory and simulation, that through a Fano interference, temperature changes can be both localized and controllably directed within certain plasmon-supporting metal nanoparticle assemblies. This occurs even when all particles are composed of the same material and contained within the same diffraction-limited spot. These anomalous thermal properties are compared and contrasted across three different nanosystems, the coupled nanorod-antenna, the heterorod dimer, and the nanocube on a substrate, known to support both spatial and spectral Fano interferences. We conclude that the presence of a Fano resonance is not sufficient by itself to induce a controllably nanolocalized temperature change. However, when present in a nanosystem of the right composition and morphology, temperature changes can be manipulated with nanoscale precision, despite thermal diffusion. PMID:26269978

  3. Miniaturized high-performance starring thermal imaging system

    NASA Astrophysics Data System (ADS)

    Cabanski, Wolfgang A.; Breiter, Rainer; Mauk, Karl-Heinz; Rode, Werner; Ziegler, Johann; Ennenga, L.; Lipinski, Ulrich M.; Wehrhahn, T.

    2000-07-01

    A high resolution thermal imaging system was developed based on a 384 X 288 mercury cadmium telluride (MCT) mid wave (MWIR) infrared (IR) detection module with a 2 X 2 microscan for improved geometrical resolution. Primary design goal was a long identification range of 3 km and high system performance for adverse weather conditions achieved by a system with small entrance pupil and minimized dimensions to fit for integration in existing apertures of armored vehicles, reconnaissance systems and stabilized platforms. A staring FPA module with its potential for long integration times together with a microscan for improved geometrical resolution provides the answers best fit to these requirements. A robust microscanner was developed to fit for military requirements and integrated with AIM's 384 X 288 MCT MWIR module and data processing. The modules allow for up to 2 ms integration time with 25 Hz frame rate and output a 768 X 576 high resolution CCIR standard image. The video image processing (VIP) provides the calculation power for scene based self learning nonuniformity correction (NUC) algorithms to save calibration sources. This NUC algorithm allows take into account non linear effects for unsurpassed performance in highly dynamic scenes. The detection module and VIP are designed to interface with STN's mature system electronics, used e.g. in hundreds of OPHELIOS thermal camera sets fielded. The system electronics provides a lot of different interface features like double serial control bus (CANBUS) interface, analog and digital outputs as well as different video outputs. The integrated graphic generation part allows to put advanced graphic overlays to the thermal image and also to external video signals via the video input feature. This electronics provides the power supply for the whole thermal imaging system as well as different processor controlled algorithms for field of view or zoom drives, focus drives, athermalization and temperature control of the FLIR. A

  4. Thermal Cyclic Behavior of Thermal and Environmental Barrier Coatings Investigated Under High-Heat-Flux Conditions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Lee, Kang N.; Miller, Robert A.

    2002-01-01

    Environmental barrier coatings (EBC's) have been developed to protect silicon-carbide- (SiC) based ceramic components in gas turbine engines from high-temperature environmental attack. With continuously increasing demands for significantly higher engine operating temperature, future EBC systems must be designed for both thermal and environmental protection of the engine components in combustion gases. In particular, the thermal barrier functions of EBC's become a necessity for reducing the engine-component thermal loads and chemical reaction rates, thus maintaining the required mechanical properties and durability of these components. Advances in the development of thermal and environmental barrier coatings (TBC's and EBC's, respectively) will directly impact the successful use of ceramic components in advanced engines. To develop high-performance coating systems, researchers must establish advanced test approaches. In this study, a laser high-heat-flux technique was employed to investigate the thermal cyclic behavior of TBC's and EBC's on SiC-reinforced SiC ceramic matrix composite substrates (SiC/SiC) under high thermal gradient and thermal cycling conditions. Because the laser heat flux test approach can monitor the coating's real-time thermal conductivity variations at high temperature, the coating thermal insulation performance, sintering, and delamination can all be obtained during thermal cycling tests. Plasma-sprayed yttria-stabilized zirconia (ZrO2-8 wt% Y2O3) thermal barrier and barium strontium aluminosilicate-based environmental barrier coatings (BSAS/BSAS+mullite/Si) on SiC/SiC ceramic matrix composites were investigated in this study. These coatings were laser tested in air under thermal gradients (the surface and interface temperatures were approximately 1482 and 1300 C, respectively). Some coating specimens were also subject to alternating furnace cycling (in a 90-percent water vapor environment at 1300 C) and laser thermal gradient cycling tests

  5. Thermal Regime of High-power Laser Diodes

    NASA Astrophysics Data System (ADS)

    Bezotosnyi, V. V.; Krokhin, O. N.; Oleshchenko, V. A.; Pevtsov, V. F.; Popov, Yu. M.; Cheshev, E. A.

    We discuss the design and application perspectives of different crystal, ceramic and composite-type submounts with thermo-compensating properties as well as submounts from materials with high thermal conductivity for overcoming thermal problem in high-power laser diodes (LD) and improving thermal management of other high-power optoelectronic and electronic semiconductor devices. Thermal fields in high-power laser diodes were calculated in 3 D thermal model at CW operation for some heatsink designs taking into account the experimental dependence of laser total efficiency against pumping current in order to extend the range of reliable operation up to thermal loads 20-30 W and corresponding output optical power up to 15-20 W for 100 μm stripe laser diodes.

  6. High-temperature turbopump assembly for space nuclear thermal propulsion

    SciTech Connect

    Overholt, D.M. )

    1993-01-20

    The development of a practical, high-performance nuclear rocket by the U.S. Air Force Space Nuclear Thermal Propulsion (SNTP) program places high priority on maximizing specific impulse (ISP) and thrust-to-weight ratio. The operating parameters arising from these goals drive the propellant-pump design. The liquid hydrogen propellant is pressurized and pumped to the reactor inlet by the turbopump assembly (TPA). Rocket propulsion is effected by rapid heating of the propellant from 100 K to thousands of degrees in the particle-bed reactor (PBR). The exhausted propellant is then expanded through a high-temperature nozzle. One approach to achieve high performance is to use an uncooled carbon-carbon nozzle and duct turbine inlet. The high-temperature capability is obtained by using carbon-carbon throughout the TPA hot section. Carbon-carbon components in development include structural parts, turbine nozzles/stators, and turbine rotors. The technology spinoff is applicable to conventional liquid propulsion engines plus a wide variety of other turbomachinery applications.

  7. Rectangular Dielectric-loaded Structures for Achieving High Acceleration Gradients

    SciTech Connect

    Wang Changbiao; Yakovlev, V. P.; Marshall, T. C.; LaPointe, M. A.; Hirshfield, J. L.

    2006-11-27

    Rectangular dielectric-loaded structures are described that may sustain higher acceleration gradients than conventional all-metal structures with similar apertures. One structure is a test cavity designed to ascertain the breakdown limits of dielectrics, while a second structure could be the basis for a two-beam accelerator. CVD diamond is an attractive dielectric for a high-gradient structure, since the published DC breakdown limit for CVD diamond is {approx} 2 GV/m, although the limit has never been determined for RF fields. Here we present a design of a diamond-lined test cavity to measure the breakdown limit. The designed cavity operates at 34 GHz, where with 10-MW input power it is expected to produce an {approx}800 MV/m field on the diamond surface - provided breakdown is avoided. The two channel rectangular dielectric-loaded waveguide could be a two-beam accelerator structure, in which a drive beam is in one channel and an accelerated beam is in the other. The RF power produced by drive bunches in the drive channel is continuously coupled to the acceleration channel. The ratio of fields in the channels (transformer ratio) for the operating mode can be designed by adjusting the dimensions of the structure. An example of the two-channel structure is described, in which a train of five 3-nC drive bunches excites wake fields in the accelerator channel of up to 1.3 GV/m with a transformer ratio of 10 for the design mode.

  8. Microbial Biosignatures in High Iron Thermal Springs

    NASA Astrophysics Data System (ADS)

    Parenteau, M. N.; Embaye, T.; Jahnke, L. L.; Cady, S. L.

    2003-12-01

    The emerging anoxic source waters at Chocolate Pots hot springs in Yellowstone National Park contain 2.6 to 11.2 mg/L Fe(II) and are 51-54° C and pH 5.5-6.0. These waters flow down the accumulating iron deposits and over three major phototrophic mat communities: Synechococcus/Chloroflexus at 51-54° C, Pseudanabaena at 51-54° C, and a narrow Oscillatoria at 36-45° C. We are assessing the contribution of the phototrophs to biosignature formation in this high iron system. These biosignatures can be used to assess the biological contribution to ancient iron deposits on Earth (e.g. Precambrian Banded Iron Formations) and, potentially, to those found on Mars. Most studies to date have focused on chemotrophic iron-oxidizing communities; however, recent research has demonstrated that phototrophs have a significant physiological impact on these iron thermal springs (Pierson et al. 1999, Pierson and Parenteau 2000, and Trouwborst et al., 2003). We completed a survey of the microfossils, biominerals, biofabrics, and lipid biomarkers in the phototrophic mats and stromatolitic iron deposits using scanning and transmission electron microscopy (SEM and TEM), energy dispersive spectrometry (EDS), powder X-ray diffraction (XRD), and gas chromatography-mass spectroscopy (GC-MS). The Synechococcus/Chloroflexus mat was heavily encrusted with iron silicates while the narrow Oscillatoria mat was encrusted primarily with iron oxides. Encrustation of the cells increased with depth in the mats. Amorphous 2-line ferrihydrite is the primary precipitate in the spring and the only iron oxide mineral associated with the mats. Goethite, hematite, and siderite were detected in dry sediment samples on the face of the main iron deposit. Analysis of polar lipid fatty acid methyl esters (FAME) generated a suite of lipid biomarkers. The Synechococcus/Chloroflexus mat contained two mono-unsaturated isomers of n-C18:1 with smaller amounts of polyunsaturated n-C18:2, characteristic of cyanobacteria

  9. The Origin of High Thermal Conductivity and Ultralow Thermal Expansion in Copper-Graphite Composites.

    PubMed

    Firkowska, Izabela; Boden, André; Boerner, Benji; Reich, Stephanie

    2015-07-01

    We developed a nanocomposite with highly aligned graphite platelets in a copper matrix. Spark plasma sintering ensured an excellent copper-graphite interface for transmitting heat and stress. The resulting composite has superior thermal conductivity (500 W m(-1) K(-1), 140% of copper), which is in excellent agreement with modeling based on the effective medium approximation. The thermal expansion perpendicular to the graphite platelets drops dramatically from ∼20 ppm K(-1) for graphite and copper separately to 2 ppm K(-1) for the combined structure. We show that this originates from the layered, highly anisotropic structure of graphite combined with residual stress under ambient conditions, that is, strain-engineering of the thermal expansion. Combining excellent thermal conductivity with ultralow thermal expansion results in ideal materials for heat sinks and other devices for thermal management. PMID:26083322

  10. Simple high-temperature thermal diffusivity apparatus

    NASA Technical Reports Server (NTRS)

    Wood, C.; Zoltan, A.

    1984-01-01

    A simple and inexpensive thermal diffusivity apparatus is described for measurement up to 1600 K. The novel features of apparatus include a light pipe, a long furnace, and a differential thermocouple. A low heat-load sample holder for clamping the sample in a vertical position is also described. The results of measurements on AXM-5Q graphite are reported.

  11. Thermal barrier coating having high phase stability

    DOEpatents

    Subramanian, Ramesh

    2002-01-01

    A device (10) comprising a substrate (22) having a deposited ceramic thermal barrier coating characterized by a microstructure having gaps (28) where the thermal barrier coating comprises a first thermal barrier layer (40), and a second thermal barrier layer (30) with a pyrochlore crystal structure having a chemical formula of A.sup.n+.sub.2-x B.sup.m+.sub.2+x O.sub.7-y, where A is selected from the group of elements consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and mixtures thereof, where B is selected from the group of elements consisting of Zr, Hf, Ti and mixtures thereof, where n and m are the valence of A and B respectively, and for -0.5.ltoreq.x.ltoreq.0.5, ##EQU1## and excluding the following combinations for x=0, y=0: A=La and B=Zr; A=La and B=Hf; A=Gd and B=Hf; and A=Yb and B=Ti.

  12. Thermal Shock Behavior of Single Crystal Oxide Refractive Concentrators for High Temperatures Solar Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Choi, Sung R.; Jacobson, Nathan S.; Miller, Robert A.

    1999-01-01

    Single crystal oxides such as yttria-stabilized zirconia (Y2O3-ZrO2), yttrium-aluminum-garnet (Y3Al5O12, or YAG), magnesium oxide (MgO) and sapphire (Al2O3) have been considered as refractive secondary concentrator materials for high temperature solar propulsion applications. However, thermal mechanical reliability of the oxide components in severe thermal environments during space mission sun/shade transitions is of great concern. In this paper, critical mechanical properties of these oxide crystals are determined by the indentation technique. Thermal shock resistance of the oxides is evaluated using a high power CO, laser under high temperature-high thermal gradients. Thermal stress fracture behavior and failure mechanisms of these oxide materials are investigated under various temperature and heating conditions.

  13. Beyond Academic Reputation: Factors that Influence the College of First Choice for High Achieving Students

    ERIC Educational Resources Information Center

    Schoenherr, Holly J.

    2009-01-01

    Studies that have investigated college choice factors for high-achieving students repeatedly cite academic reputation as one of the top indicators of choice but have not indicated why some high-achieving students choose to attend universities with a less prestigious reputation than the more highly prestigious options available to them. The purpose…

  14. The Chinese High School Student's Stress in the School and Academic Achievement

    ERIC Educational Resources Information Center

    Liu, Yangyang; Lu, Zuhong

    2011-01-01

    In a sample of 466 Chinese high school students, we examined the relationships between Chinese high school students' stress in the school and their academic achievements. Regression mixture modelling identified two different classes of the effects of Chinese high school students' stress on their academic achievements. One class contained 87% of…

  15. Does High School Facility Quality Affect Student Achievement? A Two-Level Hierarchical Linear Model

    ERIC Educational Resources Information Center

    Bowers, Alex J.; Urick, Angela

    2011-01-01

    The purpose of this study is to isolate the independent effects of high school facility quality on student achievement using a large, nationally representative U.S. database of student achievement and school facility quality. Prior research on linking school facility quality to student achievement has been mixed. Studies that relate overall…

  16. The Effects of Web-Based/Non-Web-Based Problem-Solving Instruction and High/Low Achievement on Students' Problem-Solving Ability and Biology Achievement

    ERIC Educational Resources Information Center

    Yu, Wen-Feng; She, Hsiao-Ching; Lee, Yu-Mei

    2010-01-01

    This study investigates the effects of two factors: the mode of problem-solving instruction (i.e. Web-based versus non-Web-based) and the level of academic achievement (i.e. high achievers versus low achievers) on students' problem-solving ability and biology achievement. A quasi-experimental design was used, in which the experimental group…

  17. Development of Mitsubishi High Thermal Performance Grid

    NASA Astrophysics Data System (ADS)

    Ikeda, Kazuo; Hoshi, Masaya

    Mitsubishi has developed a new zircalloy grid spacer for PWR fuel with higher thermal performance. Computational Fluid Dynamics (CFD) evaluation method has been applied for designing of the new lower pressure loss and higher Departure from Nucleate Boiling (DNB) benefit grid spacer. Reduction of pressure loss of grid structures has been examined by CFD. Also, CFD has been developed as a design tool to predict the coolant mixing ability of vane structures, which is to compare the relative peak spot temperatures around fuel rods at the same heat flux condition. Prototype grids were manufactured and several tests, which were pressure loss measurements, cross-flow measurements and freon DNB tests, were conducted to verify CFD predictions. It is concluded that the applicability of the CFD evaluation method for the thermal hydraulic design of the grid is confirmed.

  18. Thermal distribution in high power optical devices with power-law thermal conductivity

    NASA Astrophysics Data System (ADS)

    Zhou, Chuanle; Grayson, M.

    2012-01-01

    We introduce a power-law approximation to model non-linear ranges of the thermal conductivity, and under this approximation derive a simple analytical expression for calculating the temperature profile in high power quantum cascade lasers and light emitting diodes. The thermal conductivity of a type II InAs/GaSb superlattice (T2SL) is used as an example, having negative or positive power-law exponents depending on the thermal range of interest. The result is an increase or decrease in the temperature, respectively, relative to the uniform thermal conductivity assumption.

  19. Environmental natural processes that achieve thermal comfort in multifamily buildings in hot-arid regions

    NASA Astrophysics Data System (ADS)

    Moreno, Paola

    Buildings, especially in hot climates, consume a lot of energy when people want to be comfortable inside them, which translates to very expensive fees each month. The most innovative response to this problem is renewable energy, that is used, in this case, to run mechanical HVAC systems. Renewable energy is the solution for many problems, but to avoid urban heat islands when using excessive HVAC systems (powered by renewables), and to solve thermal comfort-related problems, there has to be other solution. The major challenge to find it would be to have a change of thinking process. If a building in a hot-arid region uses natural processes to emulate the functions of HVAC systems, and the proper passive strategies, then, it will provide thermal comfort to its users, diminishing the need of a mechanical system. This hypothesis will be carried out by extracting the natural processes found in a specific case in nature, applying them into a building's design, and then simulating its energy efficiency with the adequate software. There will be a comparison of the same proposed building without the natural processes, to have tangible numbers showing that these proposed strategies, in fact, work. With explanatory detailed diagrams and the energy analysis, the hypothesis could be proven correct or incorrect. The significance of this approach relies on the proximity to the natural processes that have been working in different aspects of life since the beginning of time. They have been there all the time, waiting until architects, engineers, and people in general use them, instead of making more new energy-using inventions. By having the numbers from a conventional building and the ones of the proposed building, and the right environmental diagrams, the experiment should be valid. In the near future, there should be more research focused on nature and its processes, in order to be able to reduce the use of mechanical systems, and with that, reduce the energy use and the carbon

  20. High Growth Rate YSZ Thermal Barrier Coatings Deposited by MOCVD Demonstrate High Thermal Cycling Lifetime

    SciTech Connect

    Varanasi, Venu G; Besmann, Theodore M; Payzant, E Andrew; Pint, Bruce A; Lothian, Janet L; Anderson, Timothy J

    2011-01-01

    Yttria-stabilized zirconia (YSZ) thermal barrier coatings (TBC) were prepared by metalorganic chemical vapor deposition (MOCVD) using Y(OBut{sup n}){sub 3}, Zr(OBut{sup n}){sub 4} precursors and O{sub 2} carrier gas. A thermodynamic analysis guided experiments by optimizing elemental molar (n) stoichiometric ratios for the (Zr-Y-O-C-H system). This analysis showed single-phase YSZ was favored at 950 C, 1 kPa, n{sub O}/(n{sub Y} + n{sub Zr}) > 30, n{sub Y}/(n{sub Y} + n{sub Zr}) = 0.06-0.10 (fixed n{sub C}, n{sub H}). Experimental YSZ growth had multiple phases (fcc, monoclinic), had a relatively high growth rate (43 {micro}m/h, 1005 C), had an Arrhenius dependence (845-950 C, E{sub a} = 53.8 {+-} 7.9 kJ/mol), had columnar grains (SEM analysis), and had a coating through-thickness n{sub Y}/(n{sub Y} + n{sub Zr}) = 0.04 (EPMA analysis). Doubling the inlet yttrium precursor mole fraction resulted in fcc YSZ growth with a coating through-thickness n{sub Y}/(n{sub Y} + n{sub Zr}) = 0.07. Hot-insertion thermal cycling of YSZ coatings on FeCrAlY bond coats showed >1000 h lifetime, matching current standards for EB-PVD YSZ coatings.

  1. An Analysis of Java Programming Behaviors, Affect, Perceptions, and Syntax Errors among Low-Achieving, Average, and High-Achieving Novice Programmers

    ERIC Educational Resources Information Center

    Rodrigo, Ma. Mercedes T.; Andallaza, Thor Collin S.; Castro, Francisco Enrique Vicente G.; Armenta, Marc Lester V.; Dy, Thomas T.; Jadud, Matthew C.

    2013-01-01

    In this article we quantitatively and qualitatively analyze a sample of novice programmer compilation log data, exploring whether (or how) low-achieving, average, and high-achieving students vary in their grasp of these introductory concepts. High-achieving students self-reported having the easiest time learning the introductory programming…

  2. High performance thermal imaging for the 21st century

    NASA Astrophysics Data System (ADS)

    Clarke, David J.; Knowles, Peter

    2003-01-01

    In recent years IR detector technology has developed from early short linear arrays. Such devices require high performance signal processing electronics to meet today's thermal imaging requirements for military and para-military applications. This paper describes BAE SYSTEMS Avionics Group's Sensor Integrated Modular Architecture thermal imager which has been developed alongside the group's Eagle 640×512 arrays to provide high performance imaging capability. The electronics architecture also supprots High Definition TV format 2D arrays for future growth capability.

  3. Measuring Thermal Diffusivity Of A High-Tc Superconductor

    NASA Technical Reports Server (NTRS)

    Powers, Charles E.; Oh, Gloria; Leidecker, Henning

    1992-01-01

    Technique for measuring thermal diffusivity of superconductor of high critical temperature based on Angstrom's temperature-wave method. Peltier junction generates temperature oscillations, which propagate with attenuation up specimen. Thermal diffusivity of specimen calculated from distance between thermocouples and amplitudes and phases of oscillatory components of thermocouple readings.

  4. Long life high reliability thermal control systems study data handbook

    NASA Technical Reports Server (NTRS)

    Scollon, T. R., Jr.; Carpitella, M. J.

    1971-01-01

    The development of thermal control systems with high reliability and long service life is discussed. Various passive and semi-active thermal control systems which have been installed on space vehicles are described. The properties of the various coatings are presented in tabular form.

  5. High-Resolution Thermal Inertia Mapping from the Mars Global Surveyor Thermal Emission Spectrometer

    USGS Publications Warehouse

    Mellon, M.T.; Jakosky, B.M.; Kieffer, H.H.; Christensen, P.R.

    2000-01-01

    High-resolution thermal inertia mapping results are presented, derived from Mars Global Surveyor (MGS) Thermal Emission Spectrometer (TES) observations of the surface temperature of Mars obtained during the early portion of the MGS mapping mission. Thermal inertia is the key property controlling the diurnal surface temperature variations, and is dependent on the physical character of the top few centimeters of the surface. It represents a complex combination of particle size, rock abundance, exposures of bedrock, and degree of induration. In this work we describe the derivation of thermal inertia from TES data, present global scale analysis, and place these results into context with earlier work. A global map of nighttime thermal-bolometer-based thermal inertia is presented at 14?? per pixel resolution, with approximately 63% coverage between 50??S and 70??N latitude. Global analysis shows a similar pattern of high and low thermal inertia as seen in previous Viking low-resolution mapping. Significantly more detail is present in the high-resolution TES thermal inertia. This detail represents horizontal small-scale variability in the nature of the surface. Correlation with albedo indicates the presence of a previously undiscovered surface unit of moderate-to-high thermal inertia and intermediate albedo. This new unit has a modal peak thermal inertia of 180-250 J m-2 K-1 s-12 and a narrow range of albedo near 0.24. The unit, covering a significant fraction of the surface, typically surrounds the low thermal inertia regions and may comprise a deposit of indurated fine material. Local 3-km-resolution maps are also presented as examples of eolian, fluvial, and volcanic geology. Some impact crater rims and intracrater dunes show higher thermal inertias than the surrounding terrain; thermal inertia of aeolian deposits such as intracrater dunes may be related to average particle size. Outflow channels and valleys consistently show higher thermal inertias than the

  6. Kapitza thermal resistance studied by high-frequency photothermal radiometry

    NASA Astrophysics Data System (ADS)

    Horny, Nicolas; Chirtoc, Mihai; Fleming, Austin; Hamaoui, Georges; Ban, Heng

    2016-07-01

    Kapitza thermal resistance is determined using high-frequency photothermal radiometry (PTR) extended for modulation up to 10 MHz. Interfaces between 50 nm thick titanium coatings and silicon or stainless steel substrates are studied. In the used configuration, the PTR signal is not sensitive to the thermal conductivity of the film nor to its optical absorption coefficient, thus the Kapitza resistance is directly determined from single thermal parameter fits. Results of thermal resistances show the significant influence of the nature of the substrate, as well as of the presence of free electrons at the interface.

  7. Thermal barrier coating on high temperature industrial gas turbine engines

    NASA Technical Reports Server (NTRS)

    Carlson, N.; Stoner, B. L.

    1977-01-01

    The thermal barrier coating used was a yttria stabilized zirconia material with a NiCrAlY undercoat, and the base engine used to establish improvements was the P&WA FT50A-4 industrial gas turbine engine. The design benefits of thermal barrier coatings include simplified cooling schemes and the use of conventional alloys in the engine hot section. Cooling flow reductions and improved heating rates achieved with thermal barrier coating result in improved performance. Economic benefits include reduced power production costs and reduced fuel consumption. Over the 30,000 hour life of the thermal barrier coated parts, fuel savings equivalent to $5 million are projected and specific power (megawatts/mass of engine airflow) improvements on the order of 13% are estimated.

  8. Thermal barrier coating having high phase stability

    DOEpatents

    Subramanian, Ramesh

    2001-01-01

    A device (10) comprising a substrate (22) having a deposited ceramic thermal barrier coating layer (20) characterized by a microstructure having gaps (28) where the thermal barrier coating (20) consists essentially of a pyrochlore crystal structure having a chemical formula consisting essentially of A.sup.n+.sub.2-x B.sup.m+.sub.2+x O.sub.7-y, where A is selected from the group of elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and mixtures thereof; where B is selected from the group of elements selected from Zr, Hf, Ti and mixtures thereof; n and m are the valence of A and B respectively, and for -0.5.ltoreq.x.ltoreq.0.5, ##EQU1## and excluding the following combinations for x=0, y=0: A=La and B=Zr; A=La and B=Hf; A=Gd and B=Hf; and A=Yb and B=Ti.

  9. Achievement of an efficient 1053 nm Nd:YLF polarized laser based on different thermal lensing effects

    NASA Astrophysics Data System (ADS)

    Wei, Yong; Xu, Shan; Huang, Chenghui; Chen, Weidong; Zhuang, Fengjiang; Huang, Lingxiong; Chen, Zhenqiang; Zhang, Ge

    2012-09-01

    The negative and positive thermal focal lengths for 1047 nm and 1053 nm were respectively demonstrated through analyzing different thermal lensing effects along the π- and σ-polarizations in a plane-parallel resonator. A compact and efficient diode-end-pumped 1053 nm Nd:YLF polarized laser is presented. As high as 11.2 W output power of the polarized 1053 nm laser has been obtained at an absorbed pump power of 22.3 W with an optical-optical efficiency of 50% and a slope efficiency of 53%. With the aid of a ray propagation matrix and a λ/4 wave plate, different thermal lensing effects for the π- and σ-polarizations have been theoretically analyzed and experimentally verified.

  10. Parent-Child Relations and Psychological Adjustment among High-Achieving Chinese and European American Adolescents

    ERIC Educational Resources Information Center

    Qin, Desiree Baolian; Rak, Eniko; Rana, Meenal; Donnellan, M. Brent

    2012-01-01

    Chinese American students are often perceived as problem-free high achievers. Recent research, however, suggests that high-achieving Chinese American students can experience elevated levels of stress, especially comparing to their peers from other ethnic groups. In this paper, we examine how family dynamics may influence psychological adjustment…

  11. High-Achieving and Average Students' Reading Growth: Contrasting School and Summer Trajectories

    ERIC Educational Resources Information Center

    Rambo-Hernandez, Karen E.; McCoach, D. Betsy

    2015-01-01

    Much is unknown about how initially high-achieving students grow academically, especially given the measurement issues inherent in assessing growth for the highest performing students. This study compared initially high-achieving and average students' growth in reading (in a cohort of third-grade students from 2,000 schools) over 3 years.…

  12. International Note: Between-Domain Relations of Chinese High School Students' Academic Achievements

    ERIC Educational Resources Information Center

    Yangyang, Liu

    2012-01-01

    The present study examined the between-domain relations of Chinese high school students' academic achievements. In a sample of 1870 Chinese 10th grade students, the results indicated that Chinese high school students' academic achievements were correlated across nine subjects. In line with the previous Western findings, the findings suggested that…

  13. The Effect of the Time Management Art on Academic Achievement among High School Students in Jordan

    ERIC Educational Resources Information Center

    Al-Zoubi, Maysoon

    2016-01-01

    This study aimed at recognizing the effect of the Time Management Art on academic achievement among high school students in the Hashemite Kingdom of Jordan. The researcher employed the descriptive-analytic research to achieve the purpose of the study where he chose a sample of (2000) high school female and male students as respondents to the…

  14. A Longitudinal Investigation of Project-Based Instruction and Student Achievement in High School Social Studies

    ERIC Educational Resources Information Center

    Summers, Emily J.; Dickinson, Gail

    2012-01-01

    This longitudinal study focused on how project-based instruction (PBI) influenced secondary social studies students' academic achievement and promoted College and Career Readiness (CCR). We explored and compared student achievement in a PBI high school versus a traditional instruction high school within the same rural school district. While…

  15. Effects of a Collaborative Science Intervention on High Achieving Students' Learning Anxiety and Attitudes toward Science

    ERIC Educational Resources Information Center

    Hong, Zuway-R.

    2010-01-01

    This study investigated the effects of a collaborative science intervention on high achieving students' learning anxiety and attitudes toward science. Thirty-seven eighth-grade high achieving students (16 boys and 21 girls) were selected as an experimental group who joined a 20-week collaborative science intervention, which integrated and utilized…

  16. Achievement of high nuclear spin polarization using lanthanides as low-temperature NMR relaxation agents.

    PubMed

    Peat, David T; Horsewill, Anthony J; Köckenberger, Walter; Perez Linde, Angel J; Gadian, David G; Owers-Bradley, John R

    2013-05-28

    Many approaches are now available for achieving high levels of nuclear spin polarization. One of these methods is based on the notion that as the temperature is reduced, the equilibrium nuclear polarization will increase, according to the Boltzmann distribution. The main problem with this approach is the length of time it may take to approach thermal equilibrium at low temperatures, since nuclear relaxation times (characterized by the spin-lattice relaxation time T1) can become very long. Here, we show, by means of relaxation time measurements of frozen solutions, that selected lanthanide ions, in the form of their chelates with DTPA, can act as effective relaxation agents at low temperatures. Differential effects are seen with the different lanthanides that were tested, holmium and dysprosium showing highest relaxivity, while gadolinium is ineffective at temperatures of 20 K and below. These observations are consistent with the known electron-spin relaxation time characteristics of these lanthanides. The maximum relaxivity occurs at around 10 K for Ho-DTPA and 20 K for Dy-DTPA. Moreover, these two agents show only modest relaxivity at room temperature, and can thus be regarded as relaxation switches. We conclude that these agents can speed up solid state NMR experiments by reducing the T1 values of the relevant nuclei, and hence increasing the rate at which data can be acquired. They could also be of value in the context of a simple low-cost method of achieving several-hundred-fold improvements in polarization for experiments in which samples are pre-polarized at low temperatures, then rewarmed and dissolved immediately prior to analysis. PMID:23588269

  17. Manifest Needs of High Ability Achieving and Underachieving Elementary School Children in a Culturally Disadvantaged Setting

    ERIC Educational Resources Information Center

    Masih, Lalit K.

    1974-01-01

    Study samples suggest that the high ability underachiever is characterized by low need for order and higher need to belong to supportive groups; the high ability achiever seems more independent and less attached to his peer group. (Author)

  18. High bandwidth piezoresistive force probes with integrated thermal actuation

    PubMed Central

    Doll, Joseph C.; Pruitt, Beth L.

    2012-01-01

    We present high-speed force probes with on-chip actuation and sensing for the measurement of pN-scale forces at the microsecond time scale. We achieve a high resonant frequency in water (1–100 kHz) with requisite low spring constants (0.3–40 pN/nm) and low integrated force noise (1–100 pN) by targeting probe dimensions on the order of 300 nm thick, 1–2 μm wide and 30–200 μm long. Forces are measured using silicon piezoresistors while the probes are actuated thermally with an aluminum unimorph and silicon heater. The piezoresistive sensors are designed using open source numerical optimization code that incorporates constraints on operating temperature. Parylene passivation enables operation in ionic media and we demonstrate simultaneous actuation and sensing. The improved design and fabrication techniques that we describe enable a 10–20 fold improvement in force resolution or measurement bandwidth over prior piezoresistive cantilevers of comparable thickness. PMID:23175616

  19. Comprehensive transient-state study for CARMENES NIR high-thermal stability

    NASA Astrophysics Data System (ADS)

    Becerril, Santiago; Sánchez, Miguel A.; Cárdenas, M. C.; Rabaza, Ovidio; Ramón, Alejandro; Abril, Miguel; Costillo, Luis P.; Morales, Rafael; Rodríguez, Alicia; Amado, Pedro J.

    2010-07-01

    CARMENES has been proposed as a next-generation instrument for the 3.5m Calar Alto Telescope. Its objective is finding habitable exoplanets around M dwarfs through radial velocity measurements (m/s level) in the near-infrared. Consequently, the NIR spectrograph is highly constraint regarding thermal/mechanical requirements. Indeed, the requirements used for the present study limit the thermal stability to +/-0.01K (within year period) over a working temperature of 243K in order to minimise radial velocity drifts. This can be achieved by implementing a solution based on several temperature-controlled rooms (TCR), whose smallest room encloses the vacuum vessel which houses the spectrograph's optomechanics. Nevertheless, several options have been taken into account to minimise the complexity of the thermal design: 1) Large thermal inertia of the system, where, given a thermal instability of the environment (typically, +/-0.1K), the optomechanical system remains stable within +/-0.01K in the long run; 2) Environment thermal control, where thermal stability is ensured by controlling the temperature of the environment surrounding the vacuum vessel. The present article also includes the comprehensive transient-state thermal analyses which have been implemented in order to make the best choice, as well as to give important inputs for the thermal layout of the instrument.

  20. The Meaning High-Achieving African-American Males in an Urban High School Ascribe to Mathematics

    ERIC Educational Resources Information Center

    Thompson, LaTasha; Davis, Julius

    2013-01-01

    Many researchers, educators, administrators, policymakers and members of the general public doubt the prevalence of high-achieving African-American males in urban high schools capable of excelling in mathematics. As part of a larger study, the current study explored the educational experiences of four high-achieving African-American males…

  1. Investigation of Thermal High Cycle and Low Cycle Fatigue Mechanisms of Thick Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dong-Ming; Miller, Robert A.

    1998-01-01

    Ceramic thermal barrier coatings have attracted increased attention for diesel engine applications. The advantages of using the ceramic coatings include a potential increase in efficiency and power density and a decrease in maintenance cost. Zirconia-based ceramics are the most important coating materials for such applications because of their low thermal conductivity, relatively high thermal expansivity and excellent mechanical properties. However, durability of thick thermal barrier coatings (TBCS) under severe temperature cycling encountered in engine conditions, remains a major question. The thermal transients associated with the start/stop and no-load/full-load engine cycle, and with the in-cylinder combustion process, generate thermal low cycle fatigue (LCF) and thermal high cycle fatigue (HCF) in the coating system. Therefore, the failure mechanisms of thick TBCs are expected to be quite different from those of thin TBCs under these temperature transients. The coating failure is related not only to thermal expansion mismatch and oxidation of the bond coats and substrates, but also to the steep thermal stress gradients induced in the coating systems. Although it has been reported that stresses generated by thermal transients can initiate surface and interface cracks in a coating system, the mechanisms of the crack propagation and of coating failure under the complex LCF and HCF conditions are still not understood. In this paper, the thermal fatigue behavior of an yttria partially stabilized zirconia coating system under simulated LCF and HCF engine conditions is investigated. The effects of LCF and HCF on surface crack initiation and propagation are also discussed.

  2. Highly anisotropic thermal conductivity of arsenene: An ab initio study

    NASA Astrophysics Data System (ADS)

    Zeraati, Majid; Vaez Allaei, S. Mehdi; Abdolhosseini Sarsari, I.; Pourfath, Mahdi; Donadio, Davide

    2016-02-01

    Elemental two-dimensional (2D) materials exhibit intriguing heat transport and phononic properties. Here we have investigated the lattice thermal conductivity of newly proposed arsenene, the 2D honeycomb structure of arsenic, using ab initio calculations. Solving the Boltzmann transport equation for phonons, we predict a highly anisotropic thermal conductivity of 30.4 and 7.8 W/mK along the zigzag and armchair directions, respectively, at room temperature. Our calculations reveal that phonons with mean free paths between 20 nm and 1 μ m provide the main contribution to the large thermal conductivity in the zigzag direction; mean free paths of phonons contributing to heat transport in the armchair directions range between 20 and 100 nm. The obtained anisotropic thermal conductivity and feasibility of synthesis, in addition to high electron mobility reported elsewhere, make arsenene a promising material for nanoelectronic applications and thermal management.

  3. Ultralow thermal conductivity in highly anion-defective aluminates.

    PubMed

    Wan, Chunlei; Qu, Zhixue; He, Yong; Luan, Dong; Pan, Wei

    2008-08-22

    Ultralow thermal conductivity (1.1 W/m.K, 1000 degrees C) in anion-deficient Ba2RAlO5 (R=Dy, Er, Yb) compounds was reported. The low thermal conductivity was then analyzed by kinetic theory. The highly defective structure of Ba2RAlO5 results in weak atomic bond strength and low sound speeds, and phonon scattering by large concentration of oxygen vacancies reduces the phonon mean free path to the order of interatomic distance. Ba2DyAlO5 exhibits the shortest phonon mean free path and lowest thermal conductivity among the three compositions investigated, which can be attributed to additional phonon scattering by DyO6 octahedron tilting as a result of a low tolerance factor. The Ba2RAlO5 (R=Dy, Er, Yb) compounds have shown great potential in high-temperature thermal insulation applications, particularly as a thermal barrier coating material. PMID:18764638

  4. High thermal conductivity lossy dielectric using a multi layer configuration

    DOEpatents

    Tiegs, Terry N.; Kiggans, Jr., James O.

    2003-01-01

    Systems and methods are described for loss dielectrics. A loss dielectric includes at least one high dielectric loss layer and at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. A method of manufacturing a loss dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. The systems and methods provide advantages because the loss dielectrics are less costly and more environmentally friendly than the available alternatives.

  5. High Strength and Thermally Stable Nanostructured Magnesium Alloys and Nanocomposites

    NASA Astrophysics Data System (ADS)

    Chang, Yuan-Wei

    Magnesium and its alloys are currently in the spotlight of global research because of the need to limit energy consumption and reduce the environmental impact. In particular, their low densities compared to other structural metals make them a very attractive alternative in the automobile and aerospace industries. However, their low strength compared to other structural materials (e.g. Al and steels) has limited their widespread application. This dissertation presents the results of developing and investigation of a high strength nanostructured magnesium-aluminum alloy and composite. The nanostructured magnesium alloy is prepared by cryomilling and consolidated by spark-plasma-sintering. Focused ion beam is used to prepare micropillars with different diameters ranging from 1.5 to 8 mum and micro-compression test is conducted by nanoindenter in order to evaluate the mechanical properties. The yield strength obtained in the present study is around three times higher than conventional magnesium alloys (120 MPa vs. 370 MPa). The yield strength of the nanostructured magnesium alloy is further improved through hot extrusion, resulting in a yield strength of 550 MPa and an ultimate strength of 580 MPa. The nanostructured magnesium alloy exhibits a strong size-dependence, and a significant improvement in strength is observed when the pillar diameter is reduced to below 3.5 mum. The deformation mechanisms of the compressed pillars were characterized using transmission electron microscopy. The size-induced strengthening is attributed to a less number of dislocation sources along with a higher activity of non-basal deformation mechanisms. We have also developed a high strength and thermally stable nanostructured magnesium composite by adding diamantane. A yield strength of 500 MPa is achieved, moreover, excellent thermal stability is demonstrated in the magnesium alloy containing diamantanes. The strength and grain size are thermally stable after annealing at 400°C for 100

  6. Designing CNR, a very high thermal neutron flux facility

    SciTech Connect

    Difilippo, F.C.

    1986-01-01

    According to a recent study (Eastman-Seitz Committee, National Academy of Science) there is a need for a new generation of steady neutron sources with a thermal neutron flux peak between 5 to 10 times 10/sup 15//cm/sup 2/ sec. Ideally the neutron source would have to operate continuously for several days (two weeks at least) with minimum time (2 to 3 days) for refueling and/or maintenance and it would also be used to irradiate materials and produce isotopes. This paper describes the preliminary design of the nuclear reactor for the proposed Center for Neutron Research (CNR). A duplication of existing designs (HFIR, (ORNL), ILL (Grenoble, France)) would imply high total power and small core life; the necessity of higher efficiencies (in terms of peak-flux-per-unit source or power) then becomes apparent. We have found analytical expressions for the efficiency in terms of a few parameters such as the volume of the source and the Fermi age and diffusion length of thermal neutrons in both the source and reflector regions. A single analytical expression can then be used for scoping the design and to intercompare radically different designs. Higher efficiencies can be achieved by reducing the volume and the moderation of a core immersed in a very low absorbing reflector; on the contrary a very long core life has a negative effect on the efficiency at beginning of life. Consequently, and after detailed calculations, we have found a candidate design with the following characteristics: core, U/sub 3/Si/sub 2/, 93% enriched, 18.1-kg /sup 235/U, metal fraction 50%, Al cladding, and 35-L volume; reflector and moderator, D/sub 2/O; efficiency at end of life (EOL) with respect to the ILL reactor, 1.29; flux at EOL, 10 x 10/sup 15//cm/sup 2/ sec (power in core 270. MW); core life, 14 days; burnup 28.4%.

  7. A high temperature molten salt thermal electrochemical cell

    NASA Astrophysics Data System (ADS)

    Plichta, Edward J.; Behl, Wishvender K.

    1990-02-01

    This invention relates in general to a high temperature molten salt thermal electrochemical cell and in particular to such a cell including cobalt oxide (Co3O4) as the cathode material. High temperature molten salt thermal electrochemical cells are widely used as power sources for projectiles, rockets, bombs, mines, missiles, decoys, jammers, and torpedoes. These are also used as fuses. Thermal electrochemical cells are reserve-type cells that can be activated by heating with a pyrotechnic heat source such as zirconium and barium chromate powders or mixtures of iron powder and potassium perchlorate.

  8. High Density Thermal Energy Storage with Supercritical Fluids

    NASA Technical Reports Server (NTRS)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  9. Thermal High- and Low-Cycle Fatigue Behavior of Thick Thermal Barrier Coating Systems

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.

    1998-01-01

    Ceramic thermal barrier coatings have received increasing attention for advanced gas turbine and diesel engine applications because of their ability to provide thermal insulation to engine components. However, the durability of these coatings under the severe thermal cycling conditions encountered in a diesel engine (ref. 1) still remains a major issue. In this research at the NASA Lewis Research Center, a high-power laser was used to investigate the thermal fatigue behavior of a yttria-stabilized zirconia coating system under simulated diesel engine conditions. The mechanisms of fatigue crack initiation and propagation, and of coating failure under complex thermal low-cycle fatigue (LCF, representing stop/start cycles) and thermal high-cycle fatigue (HCF, representing operation at 1300 rpm) are described. Continuous wave and pulse laser modes were used to simulate pure LCF and combined LCF/HCF, respectively (ref. 2). The LCF mechanism was found to be closely related to the coating sintering and creep at high temperatures. These creep strains in the ceramic coating led to a tensile stress state during cooling, thus providing the major driving force for crack growth under LCF conditions. The combined LCF/HCF tests induced more severe coating surface cracking, microspallation, and accelerated crack growth than did the pure LCF test. HCF thermal loads also facilitated lateral crack branching and ceramic/bond coat interface delaminations. HCF is associated with the cyclic stresses originating from the high-frequency temperature fluctuation at the ceramic coating surface. The HCF thermal loads act on the crack by a wedging mechanism (ref. 1), resulting in continuous crack growth at temperature. The HCF stress intensity factor amplitude increases with the interaction depth and temperature swing, and decreases with the crack depth. HCF damage also increases with the thermal expansion coefficient and the Young's modulus of the ceramic coating (refs. 1 and 3).

  10. Applications of high thermal conductivity composites to electronics and spacecraft thermal design

    NASA Technical Reports Server (NTRS)

    Sharp, G. Richard; Loftin, Timothy A.

    1990-01-01

    Recently, high thermal conductivity graphite fiber-reinforced metal matrix composites (MMCs) have become available that can save weight over present methods of heat conduction. Another significant advantage is that these materials can be used without the plumbing and testing complexities that accompany the use of liquid heat pipes. A spinoff of this research was the development of other MMCs as electronic device heat sinks. These use particulates rather than fibers and are formulated to match the coefficient of thermal expansion of electronic substrates in order to alleviate thermally induced stresses. The development of both types of these materials as viable weight-saving substitutes for the traditional methods of thermal control for electronics packaging and also for spacecraft thermal control applications are the subjects of this report.

  11. The impact of collective teacher efficacy on student achievement in high school science

    NASA Astrophysics Data System (ADS)

    Burcham, Mark W.

    This dissertation was designed to examine the impact of collective teacher efficacy on high school science achievement by looking at relationships among collective teacher efficacy, its two constructs, group competence and group task analysis, and high school science achievement scores at four rural high schools in Northwestern North Carolina. The researcher gathered historical test data from the testing coordinator from the school system and then administered the Collective Teacher Efficacy Instrument, developed by Goddard, Hoy, and Woolfolk Hoy (2000), to 24 science teachers from the four high schools. Using this information, the researcher conducted statistical analyses to determine the relationships among collective teacher efficacy, group competence, and group task analysis as compared with the tested science curriculum (physical science, biology, chemistry, and physics). The researcher also examined which construct was the most contributing factor and examined differences in efficacy levels and student achievement levels at each high school. Analysis of the data from this study indicated collective teacher efficacy, as well as its two constructs, group competence and group task analysis, does have a positive impact on student achievement in high school science. Analysis of the data revealed group competence is the major contributing factor for student achievement in biology and group task analysis is the major contributing factor for student achievement in physical science, chemistry, and physics. Further analysis of the data in this study, also revealed that the two high schools with the highest levels of collective teacher efficacy had the highest levels of student achievement.

  12. Experimental measurements of thermal properties of high-temperature refractory materials used for thermal energy storage

    NASA Astrophysics Data System (ADS)

    El-Leathy, Abdelrahman; Jeter, Sheldon; Al-Ansary, Hany; Abdel-Khalik, Said; Golob, Matthew; Danish, Syed Noman; Saeed, Rageh; Djajadiwinata, Eldwin; Al-Suhaibani, Zeyad

    2016-05-01

    This paper builds on studies conducted on thermal energy storage (TES) systems that were built as a part of the work performed for a DOE-funded SunShot project titled "High Temperature Falling Particle Receiver". In previous studies, two small-scale TES systems were constructed for measuring heat loss at high temperatures that are compatible with the falling particle receiver concept, both of which had shown very limited heat loss. Through the course of those studies, it became evident that there was a lack of information about the thermal performance of some of the insulating refractory materials used in the experiments at high temperatures, especially insulating firebrick and perlite concrete. This work focuses on determining the thermal conductivities of those materials at high temperatures. The apparatus consists of a prototype cylindrical TES bin built with the same wall construction used in previous studies. An electric heater is placed along the centerline of the bin, and thermocouples are used to measure temperature at the interfaces between all layers. Heat loss is measured across one of the layers whose thermal conductivity had already been well established using laboratory experiments. This value is used to deduce the thermal conductivity of other layers. Three interior temperature levels were considered; namely, 300°C, 500°C, and 700°C. Results show that the thermal conductivity of insulating firebrick remains low (approximately 0.22 W/m.K) at an average layer temperature as high as 640°C, but it was evident that the addition of mortar had an impact on its effective thermal conductivity. Results also show that the thermal conductivity of perlite concrete is very low, approximately 0.15 W/m.K at an average layer temperature of 360°C. This is evident by the large temperature drop that occurs across the perlite concrete layer. These results should be useful for future studies, especially those that focus on numerical modeling of TES bins.

  13. High voltage thermally diffused p(+)n solar cells

    NASA Technical Reports Server (NTRS)

    Faur, M.; Faur, M.; Flood, D. J.; Brinker, D. J.; Weinberg, I.; Goradia, C.; Fatemi, N.; Goradia, M.; Thesling, W.

    1991-01-01

    The possibility of fabricating thermally diffused p(+)n InP solar-cells with high open-circuit voltage without sacrificing the short circuit current is discussed. The p(+)n InP junctions were formed by Cd and Zn diffusion through a 3-5-nm-thick anodic or chemical phosphorus-rich oxide cap layer grown on n:InP:S (with ND-NA = 3.5 x 10 exp 16 and 4.5 x 10 exp 17/cu cm) Czochralski LEC-grown substrates. After thinning the emitter from its initial thickness of 1 to 2.5 micron down to 0.06-0.15 micron, the maximum efficiency was found when the emitter was 0.2 to 0.3 micron thick. Typical AM0, 25 C values of 854-860 mV were achieved for Voc, Jsc values were from 25.9 to 29.1 mA/sq cm using only the P-rich passivating layer left after the thinning process as an antireflection coating.

  14. High-resolution QWIP thermal imager for AFV upgrade

    NASA Astrophysics Data System (ADS)

    Dahlberg, Anders G. M.

    2004-08-01

    Following on the success of the BIRC clip on thermal imaging sight for the BILL Anti-Tank Missile System, which was in fact the world's first military QWIP based thermal imager, and which has been successfully delivered to the Swedish Army in serial quantities, several new QWIP-based products from FLIR Systems AB in Sweden are now under contract for defense customers worldwide. These include the new Forward Observation Systems for Norway and Sweden, Airborne Search & Rescue Systems, and a new clip on thermal imager for the Bofors RBS 70 Air Defense Missile System. The latest of these products is the development of a High Resolution QWIP Thermal Imager, LIRC, under contract for an upgrade of a number of Swedish CV9040C Armored Fighting Vehicles for Swedish Army International Operations. The paper will focus on the rationale behind the system selection, the development of the military qualified QWIP Thermal Imagers and the current status of the program.

  15. Thermal Transport in High-Strength Polymethacrylimide (PMI) Foam Insulations

    NASA Astrophysics Data System (ADS)

    Qiu, L.; Zheng, X. H.; Zhu, J.; Tang, D. W.; Yang, S. Y.; Hu, A. J.; Wang, L. L.; Li, S. S.

    2015-11-01

    Thermal transport in high-strength polymethacrylimide (PMI) foam insulations is described, with special emphasis on the density and temperature effects on the thermal transport performance. Measurements of the effective thermal conductivity are performed by a freestanding sensor-based 3ω method. A linear relationship between the density and the effective thermal conductivity is observed. Based on the analysis of the foam insulation morphological structures and the corresponding geometrical cell model, the quantitative contribution of the solid conductivity and the gas conductivity as well as the radiative conductivity to the total effective thermal conductivity as a function of the density and temperature is calculated. The agreement between the curves of the results from the developed model and experimental data indicate the model can be used for PMI foam insulating performance optimization.

  16. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process

    NASA Astrophysics Data System (ADS)

    Wang, Hui–Yuan; Yu, Zhao–Peng; Zhang, Lei; Liu, Chun–Guo; Zha, Min; Wang, Cheng; Jiang, Qi–Chuan

    2015-11-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application.

  17. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process

    PubMed Central

    Wang, Hui–Yuan; Yu, Zhao–Peng; Zhang, Lei; Liu, Chun–Guo; Zha, Min; Wang, Cheng; Jiang, Qi–Chuan

    2015-01-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30–60 μm, exhibiting a typical basal texture, fine grains of 1–5 μm and ultrafine (sub) grains of 200–500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application. PMID:26603776

  18. Achieving high strength and high ductility in magnesium alloy using hard-plate rolling (HPR) process.

    PubMed

    Wang, Hui-Yuan; Yu, Zhao-Peng; Zhang, Lei; Liu, Chun-Guo; Zha, Min; Wang, Cheng; Jiang, Qi-Chuan

    2015-01-01

    Magnesium alloys are highly desirable for a wide range of lightweight structural components. However, rolling Mg alloys can be difficult due to their poor plasticity, and the strong texture yielded from rolling often results in poor plate forming ability, which limits their further engineering applications. Here we report a new hard-plate rolling (HPR) route which achieves a large reduction during a single rolling pass. The Mg-9Al-1Zn (AZ91) plates processed by HPR consist of coarse grains of 30-60 μm, exhibiting a typical basal texture, fine grains of 1-5 μm and ultrafine (sub) grains of 200-500 nm, both of the latter two having a weakened texture. More importantly, the HPR was efficient in gaining a simultaneous high strength and uniform ductility, i.e., ~371 MPa and ~23%, respectively. The superior properties should be mainly attributed to the cooperation effect of the multimodal grain structure and weakened texture, where the former facilitates a strong work hardening while the latter promotes the basal slip. The HPR methodology is facile and effective, and can avoid plate cracking that is prone to occur during conventional rolling processes. This strategy is applicable to hard-to-deform materials like Mg alloys, and thus has a promising prospect for industrial application. PMID:26603776

  19. Detection of a buried horizon with a high thermal diffusivity using thermal remote sensing

    NASA Technical Reports Server (NTRS)

    Nash, David B.

    1988-01-01

    A field investigation using thermal remote sensing was performed to test the feasibility of detecting the surface topography of granite bedrock beneath a thin cover of alluvium. Imagery of a region of the Mojave Desert were taken with an airborne multispectral scanner with thermal spectral bandwidths of 10.4 and 12.5 microns an instantaneous field of view of 2.5 mrad. It is suggested that a buried high thermal diffusivity horizon measurably lowers the surface temperature of the overlying lower diffusivity material during the peak of the annual heating cycle.

  20. An Investigation of Student Characteristics as Related to Achievement in an Individualized High School Biology Program.

    ERIC Educational Resources Information Center

    Littlefield, David L.

    Reported is a study of possible differences in student characteristics between high, expected, and low achievers in an individualized learning biology program. Nine variables, ranging from biographical data through attitudinal data were studied. Effects on achievement and explanation of some of the differences were determined by examination of…

  1. The Effects of Cooperative Learning on Student Achievement and Motivation in a High School Geometry Class.

    ERIC Educational Resources Information Center

    Nichols, Joe D.; Hall, Neff

    In this study, the effects of a form of cooperative group instruction (Student Teams Achievement Divisions) on student motivation and achievement in a high school geometry class were examined. Ninety (mostly 10th-grade) students were randomly assigned to either a control group receiving traditional instruction or one of two treatment groups…

  2. The Effects of Explicit Teaching of Metastrategic Knowledge on Low- And High-Achieving Students

    ERIC Educational Resources Information Center

    Zohar, Anat; Peled, Bracha

    2008-01-01

    This study assessed the effects of explicit teaching of metastrategic knowledge (MSK) on gains of low-achieving (LA) and high-achieving (HA) 5th grade students (N=41). Gains in reasoning scores of students from the Experimental group (compared to students from the control group) were obtained on the strategic and on the metastrategic level. Gains…

  3. A Quantitative Comparison of Pennsylvania High School Student Achievement by Middle States Association's Accreditation Status

    ERIC Educational Resources Information Center

    Johnson, Christopher A.

    2012-01-01

    As public school accountability for student achievement has continued to increase, prior to and as a result of the No Child Left Behind Act of 2001, schools have sought ways of bringing new instructional services to their students to raise their levels of achievement. Some Pennsylvania public high schools have attempted to improve student…

  4. Unforgiving Confucian Culture: A Breeding Ground for High Academic Achievement, Test Anxiety and Self-Doubt?

    ERIC Educational Resources Information Center

    Stankov, Lazar

    2010-01-01

    This paper reviews findings from several studies that contribute to our understanding of cross-cultural differences in academic achievement, anxiety and self-doubt. The focus is on comparisons between Confucian Asian and European regions. Recent studies indicate that high academic achievement of students from Confucian Asian countries is…

  5. An Analysis of Mathematics Course Sequences for Low Achieving Students at a Comprehensive Technical High School

    ERIC Educational Resources Information Center

    Edge, D. Michael

    2011-01-01

    This non-experimental study attempted to determine how the different prescribed mathematic tracks offered at a comprehensive technical high school influenced the mathematics performance of low-achieving students on standardized assessments of mathematics achievement. The goal was to provide an analysis of any statistically significant differences…

  6. Instructional, Transformational, and Managerial Leadership and Student Achievement: High School Principals Make a Difference

    ERIC Educational Resources Information Center

    Valentine, Jerry W.; Prater, Mike

    2011-01-01

    This statewide study examined the relationships between principal managerial, instructional, and transformational leadership and student achievement in public high schools. Differences in student achievement were found when schools were grouped according to principal leadership factors. Principal leadership behaviors promoting instructional and…

  7. Scholastic Achievement in High School Explained? Validation of a Longitudinal Structural Equations Model

    ERIC Educational Resources Information Center

    Hellle, Laura; Tuijula, Tiina; Laakkonen, Eero

    2009-01-01

    The purpose of the study is to shed light on the mechanisms behind scholastic achievement in high school by testing a structural equations model based on the work by Vermunt (1998). It was presumed that self-regulation of learning would predict scholastic achievement and that learning orientations would predict self-regulation of learning. A…

  8. Predicting Early Academic Failure in High School from Prior Academic Achievement, Psychosocial Characteristics, and Behavior

    ERIC Educational Resources Information Center

    Casillas, Alex; Robbins, Steve; Allen, Jeff; Kuo, Yi-Lung; Hanson, Mary Ann; Schmeiser, Cynthia

    2012-01-01

    The authors examined the differential effects of prior academic achievement, psychosocial, behavioral, demographic, and school context factors on early high school grade point average (GPA) using a prospective study of 4,660 middle-school students from 24 schools. The findings suggest that (a) prior grades and standardized achievement are the…

  9. Accelerated Mathematics and High-Ability Students' Math Achievement in Grades Three and Four

    ERIC Educational Resources Information Center

    Stanley, Ashley M.

    2011-01-01

    The purpose of this study was to explore the relationship between the use of a computer-managed integrated learning system entitled Accelerated Math (AM) as a supplement to traditional mathematics instruction on achievement as measured by TerraNova achievement tests of third and fourth grade high-ability students. Gender, socioeconomic status, and…

  10. Early Reading Skills and Academic Achievement Trajectories of Students Facing Poverty, Homelessness, and High Residential Mobility

    ERIC Educational Resources Information Center

    Herbers, Janette E.; Cutuli, J. J.; Supkoff, Laura M.; Heistad, David; Chan, Chi-Keung; Hinz, Elizabeth; Masten, Ann S.

    2012-01-01

    This investigation tested the importance of early academic achievement for later achievement trajectories among 18,011 students grouped by level of socioeconomic risk. Students considered to be at highest risk were those who experienced homelessness or high residential mobility (HHM). HHM students were compared with students eligible for free…

  11. Gender and High School Chemistry: Student Perceptions on Achievement in a Selective Setting

    ERIC Educational Resources Information Center

    Cousins, Andrew; Mills, Martin

    2015-01-01

    This paper reports on research undertaken in a middle-class Australian school. The focus of the research was on the relationship between gender and students' engagement with high school chemistry. Achievement data from many OECD [Organisation for Economic Co-operation and Development] countries suggest that middle-class girls are achieving equally…

  12. Cohort versus Non-Cohort High School Students' Math Performance: Achievement Test Scores and Coursework

    ERIC Educational Resources Information Center

    Parke, Carol S.; Keener, Dana

    2011-01-01

    The purpose of this study is to compare multiple measures of mathematics achievement for 1,378 cohort students who attended the same high school in a district from 9th to 12th grade with non-cohort students in each grade level. Results show that mobility had an impact on math achievement. After accounting for gender, ethnicity, and SES, adjusted…

  13. The Impact of Charter Schools on Promoting High Levels of Mathematics Achievement

    ERIC Educational Resources Information Center

    Plucker, Jonathan A.; Makel, Matthew C.; Rapp, Kelly E.

    2007-01-01

    This study compares achievement levels for high ability students attending charter schools and students in traditional public schools in Georgia. Researchers examined student achievement (as assessed by the state's Criterion-Referenced Competency Tests) using three comparison groups: students in the closest traditional schools with similar grade…

  14. The Impact of Placement on Reading and Mathematics Achievement of Students with High Incidence Disabilities

    ERIC Educational Resources Information Center

    Harrington, Jennifer Stell

    2011-01-01

    The question of where best to educate students with disabilities to maximize their academic achievement has been discussed and researched for over four decades, with inconsistent and contradictory results. This study focused on the mathematics and reading achievement of middle and high school students with mild disabilities in an urban district in…

  15. Parental Involvement, Homework, and TV Time: Direct and Indirect Effects on High School Achievement.

    ERIC Educational Resources Information Center

    Keith, Timothy Z.; And Others

    1986-01-01

    A set of High School and Beyond data was used to study the effect of three variables on academic achievement. Homework had a positive effect, TV a negative, and parental involvement no direct effect on seniors' achievement scores, but influenced the amount of time students spent on homework. (Author/JAZ)

  16. Low and High Mathematics Achievement in Japanese, Chinese, and American Elementary-School Children.

    ERIC Educational Resources Information Center

    Uttal, David H.; And Others

    1988-01-01

    First and fifth grade students who scored high or low on a mathematics test were tested for intellectual ability and reading achievement. Students and their mothers were interviewed. Results indicated that factors associated with levels of achievement in mathematics operate in a similar fashion across three cultures that differ greatly in their…

  17. Achieving high performance polymer optoelectronic devices for high efficiency, long lifetime and low fabrication cost

    NASA Astrophysics Data System (ADS)

    Huang, Jinsong

    This thesis described three types of organic optoelectronic devices: polymer light emitting diodes (PLED), polymer photovoltaic solar cell, and organic photo detector. The research in this work focuses improving their performance including device efficiency, operation lifetime simplifying fabrication process. With further understanding in PLED device physics, we come up new device operation model and improved device architecture design. This new method is closely related to understanding of the science and physics at organic/metal oxide and metal oxide/metal interface. In our new device design, both material and interface are considered in order to confine and balance all injected carriers, which has been demonstrated very be successful in increasing device efficiency. We created two world records in device efficiency: 18 lm/W for white emission fluorescence PLED, 22 lm/W for red emission phosphorescence PLED. Slow solvent drying process has been demonstrated to significantly increase device efficiency in poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C 61-butyric acid methyl ester (PCBM) mixture polymer solar cell. From the mobility study by time of flight, the increase of efficiency can be well correlated to the improved carrier transport property due to P3HT crystallization during slow solvent drying. And it is found that, similar to PLED, balanced carrier mobility is essential in high efficient polymer solar cell. There is also a revolution in our device fabrication method. A unique device fabrication method is presented by an electronic glue based lamination process combined with interface modification as a one-step polymer solar cell fabrication process. It can completely skip the thermal evaporation process, and benefit device lifetime by several merits: no air reactive. The device obtained is metal free, semi-transparent, flexible, self-encapsulated, and comparable efficiency with that by regular method. We found the photomultiplication (PM) phenomenon in C

  18. Highly directional thermal emission from two-dimensional silicon structures.

    PubMed

    Ribaudo, Troy; Peters, David W; Ellis, A Robert; Davids, Paul S; Shaner, Eric A

    2013-03-25

    We simulate, fabricate, and characterize near perfectly absorbing two-dimensional grating structures in the thermal infrared using heavily doped silicon (HdSi) that supports long wave infrared surface plasmon polaritons (LWIR SPP's). The devices were designed and optimized using both finite difference time domain (FDTD) and rigorous coupled wave analysis (RCWA) simulation techniques to satisfy stringent requirements for thermal management applications requiring high thermal radiation absorption over a narrow angular range and low visible radiation absorption over a broad angular range. After optimization and fabrication, characterization was performed using reflection spectroscopy and normal incidence emissivity measurements. Excellent agreement between simulation and experiment was obtained. PMID:23546065

  19. Design of a High Thermal Gradient Bridgman Furnace

    NASA Technical Reports Server (NTRS)

    LeCroy, J. E.; Popok, D. P.

    1994-01-01

    The Advanced Automated Directional Solidification Furnace (AADSF) is a Bridgman-Stockbarger microgravity processing facility, designed and manifested to first fly aboard the second United States Microgravity Payload (USMP-2) Space Shuttle mission. The AADSF was principally designed to produce high axial thermal gradients, and is particularly suitable for metals solidification experiments, including non-dilute alloys. To accommodate a wider range of experimental conditions, the AADSF is equipped with a reconfigurable gradient zone. The overall design of the AADSF and the relationship between gradient zone design and furnace performance are described. Parametric thermal analysis was performed and used to select gradient zone design features that fulfill the high thermal gradient requirements of the USMP-2 experiment. The thermal model and analytical procedure, and parametric results leading to the first flight gradient zone configuration, are presented. Performance for the USMP-2 flight experiment is also predicted, and analysis results are compared to test data.

  20. High pressure elasticity and thermal properties of depleted uranium

    NASA Astrophysics Data System (ADS)

    Jacobsen, M. K.; Velisavljevic, N.

    2016-04-01

    Studies of the phase diagram of uranium have revealed a wealth of high pressure and temperature phases. Under ambient conditions the crystal structure is well defined up to 100 gigapascals (GPa), but very little information on thermal conduction or elasticity is available over this same range. This work has applied ultrasonic interferometry to determine the elasticity, mechanical, and thermal properties of depleted uranium to 4.5 GPa. Results show general strengthening with applied load, including an overall increase in acoustic thermal conductivity. Further implications are discussed within. This work presents the first high pressure studies of the elasticity and thermal properties of depleted uranium metal and the first real-world application of a previously developed containment system for making such measurements.

  1. Manifest Needs of High Ability Achieving and Underachieving Elementary School Children in a Culturally Disadvantaged Setting

    ERIC Educational Resources Information Center

    Masih, Lalit K.

    1974-01-01

    This study, conducted in conjunction with a larger project entitled "Project Able" (part of the Madison Area Project), compared manifest needs of high ability achieving and underachieving elementary school children in a culturally disadvantaged setting. (EAK)

  2. Understanding the Elements of Operational Reliability: A Key for Achieving High Reliability

    NASA Technical Reports Server (NTRS)

    Safie, Fayssal M.

    2010-01-01

    This viewgraph presentation reviews operational reliability and its role in achieving high reliability through design and process reliability. The topics include: 1) Reliability Engineering Major Areas and interfaces; 2) Design Reliability; 3) Process Reliability; and 4) Reliability Applications.

  3. Applications of high thermal conductivity composites to electronics and spacecraft thermal design

    NASA Technical Reports Server (NTRS)

    Sharp, G. Richard; Loftin, Timothy A.

    1990-01-01

    Recently, high thermal conductivity continuous graphite fiber reinforced metal matrix composites (MMC's) have become available that can save much weight over present methods of heat conduction. These materials have two or three times higher thermal conductivity in the fiber direction than the pure metals when compared on a thermal conductivity to weight basis. Use of these materials for heat conduction purposes can result in weight savings of from 50 to 70 percent over structural aluminum. Another significant advantage is that these materials can be used without the plumbing and testing complexities that accompany the use of liquid heat pipes. A spinoff of this research was the development of other MMC's as electronic device heat sinks. These use particulates rather than fibers and are formulated to match the coefficient of thermal expansion of electronic substrates in order to alleviate thermally induced stresses. The development of both types of these materials as viable weight saving substitutes for traditional methods of thermal control for electronics packaging and also for spacecraft thermal control applications are the subject of this report.

  4. Bullying and Victimization Rates among Gifted and High-Achieving Students

    ERIC Educational Resources Information Center

    Peters, Megan Parker; Bain, Sherry K.

    2011-01-01

    Bullying and victimization rates among 90 gifted and nongifted, high-achieving (HA) high school students were assessed by using the Reynolds Bully Victimization Scale (BVS; W. M. Reynolds, 2003). The mean scores indicate that gifted and HA high school students bully others and are victimized by others generally at unelevated rates based on BVS…

  5. A Study of Professional Learning Communities and Science Achievement in Large High Schools

    ERIC Educational Resources Information Center

    Kincannon, Susan D.

    2010-01-01

    The purpose of this study was to compare the science achievement and high school completion rates of students in a large high school implementing professional learning community concepts and practices with two large high schools not participating in professional learning community concepts and practices. The primary methodology employed was a…

  6. Do Peers Influence Achievement in High School Economics? Evidence from Georgia's Economics End of Course Test

    ERIC Educational Resources Information Center

    Clark, Christopher; Scafidi, Benjamin; Swinton, John R.

    2011-01-01

    The authors provide the first estimates of the impact of peers on achievement in high school economics. The estimates are obtained by analyzing three years of data on all high school students who take Georgia's required economics course and its accompanying high-stakes End of Course Test (Georgia Department of Education). They use an instrumental…

  7. Thermal Conductivity Measurements in Metals at High Pressures and Temperatures.

    NASA Astrophysics Data System (ADS)

    Konopkova, Z.; McWilliams, R. S.; Goncharov, A.

    2014-12-01

    The transport properties of iron and iron alloys at high pressures and temperatures are crucial parameters in planetary evolution models, yet are difficult to determine both theoretically and experimentally. Estimates of thermal conductivity in the Earth's core range from 30 to 150 W/mK, a substantial range leaving many open questions regarding the age of the inner core, the thermal structure of the outer core, and the conditions for a working geodynamo. Most experiments have measured electrical resistivity rather than directly measuring thermal conductivity, and have used models to extrapolate from low-temperature data to the high temperature conditions of the core. Here we present direct, in-situ high-pressure and high-temperature measurements of the thermal conductivity of metals in the diamond-anvil cell. Double-sided continuous laser heating is combined with one-side flash heating of a metallic foil, while the time-resolved temperature is measured from both sides with spectral radiometry in an optical streak camera. Emission and temperature perturbations measured on opposite sides of the foil were modeled using finite element calculations in order to extract thermal diffusivity and conductivity of foils. Results on platinum and iron at high pressures and temperatures will be presented.

  8. Thermal design and flight validation for high precision camera

    NASA Astrophysics Data System (ADS)

    Meng, Henghui; Sun, Lixia; Zhang, Chuanqiang; Geng, Liyin

    2015-10-01

    High precision camera, designed for advanced optical system, with a wide field of vision, high resolution and fast response, has a wild range of applications. As the main payload for spacecraft, the optical remote sensor is mounted exposed to the space, which means it should have a reliable optical performance in harsh space environment during lifetime. Because of the special optical characteristic, imaging path should be accurate, and less thermal deformation for the optical parts is required in the working process, so the high precision camera has a high level requirement for temperature. High resolution space camera is generally required to own the capability of adapting to space thermal environments. The flexible satellite's change of rolling attitude affects the temperature distribution of the camera and makes a difference to optical performance. The thermal control design of space camera is presented, and analysis the temperature data in orbit to prove the thermal design correct. It is proved that the rolling attitude has more influence on outer parts and less influence on inner parts, and active thermal control can weaken the influence of rolling attitude.

  9. Thermal Conductivity and Elastic Modulus Evolution of Thermal Barrier Coatings under High Heat Flux Conditions

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1999-01-01

    Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may he encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8%Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m-K to 1. 15 W/m-K, 1. 19 W/m-K and 1.5 W/m-K after 30 hour testing at surface temperatures of 990C, 1100C, and 1320C. respectively. Hardness and modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and micro-indentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface, and to 7.5 GPa at the ceramic coating surface after 120 hour testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced micro-porosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various thermal barrier coating applications.

  10. Measurement of thermal diffusivity of rocks at high pressure

    SciTech Connect

    Mirkovich, V.V.; Durham, W.B.; Heard, H.C.

    1982-10-01

    A method for measurement of thermal diffusivity at high hydrostatic pressure was developed by adapting a radial symmetry heat flow method wherein a sinusoidal heat wave is applied to the cylindrical surface of the sample. The accuracy of the measuring system was tested using Pyroceram 9606. Data obtained were within 5% of published values at all temperatures to 400/sup 0/C and no dependence upon pressure was observed. Thermal diffusivity of three crystalline igneous rock specimens was measured at temperatures from 32 to 400/sup 0/C and pressures from 0.1 to 200 MPa. The results for Creighton quartz diorite showed only limited temperature and pressure dependence. In the case of Stripa and Westerly granites, this dependence was found to be more substantial. Thermal diffusivity of Stripa granite decreased by more than 50% from 32 to 400/sup 0/C and that of Westerly granite decreased by approximately 40% over the same range. At 32/sup 0/C and 200 MPa, thermal diffusivity for both rocks was higher by approximately 10% than that measured at 0.1 MPa. At higher temperatures the difference in thermal diffusivity between the two pressure levels increased. An anomaly was observed in Stripa and Westerly granite in the temperature range 32 to 65/sup 0/C: thermal diffusivity increased with increasing temperature. The anomaly is consistent with recently observed thermal expansivity in these rocks as a function of pressure and temperature.

  11. Investigation of Thermal High Cycle and Low Cycle Fatigue Mechanisms of Thick Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1998-01-01

    Thick thermal barrier coating systems in a diesel engine experience severe thermal low cycle fatigue (LCF) and high cycle fatigue (HCF) during engine operation. In this paper, the mechanisms of fatigue crack initiation and propagation in a ZrO2-8wt% Y2O3 thermal barrier coating, under simulated engine thermal LCF and HCF conditions, are investigated using a high power CO2 laser. Experiments showed that the combined LCF-HCF tests induced more severe coating surface cracking, microspallation and accelerated crack growth, as compared to the pure LCF test. Lateral crack branching and the ceramic/bond coat interface delaminations were also facilitated by HCF thermal loads, even in the absence of severe interfacial oxidation. Fatigue damage at crack wake surfaces, due to such phenomena as asperity/debris contact induced cracking and splat pull-out bending during cycling, was observed especially for the combined LCF-HCF tests. It is found that the failure associated with LCF is closely related to coating sintering and creep at high temperatures, which induce tensile stresses in the coating after cooling. The failure associated with HCF process, however, is mainly associated with a surface wedging mechanism. The interaction between the LCF, HCF and ceramic coating creep, and the relative importance of LCF and HCF in crack propagation are also discussed based on the experimental evidence.

  12. Investigation of Thermal High Cycle and Low Cycle Fatigue Mechanisms of Thick Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Miller, Robert A.

    1998-01-01

    Thick thermal barrier coating systems in a diesel engine experience severe thermal low cycle fatigue (LCF) and high cycle fatigue (HCF) during engine operation. In this paper, the mechanisms of fatigue crack initiation and propagation in a ZrO2-8wt.% Y2O3 thermal barrier coating, under simulated engine thermal LCF and HCF conditions, are investigated using a high power CO2 laser. Experiments showed that the combined LCF/HCF tests induced more severe coating surface cracking, microspallation and accelerated crack growth, as compared to the pure LCF test. Lateral crack branching and the ceramic/bond coat interface delaminations were also facilitated by HCF thermal loads, even in the absence of severe interfacial oxidation. Fatigue damages at crack wake surfaces, due to such phenomena as asperity/debris contact induced cracking and splat pull-out bending during cycling, were observed especially for the combined LCF/HCF tests. It is found that the failure associated with LCF is closely related to coating sintering and creep at high temperatures, which induce tensile stresses in the coating after cooling. The failure associated with HCF process, however, is mainly associated with a surface wedging mechanism. The interaction between the LCF, HCF and ceramic coating creep, and the relative importance of LCF and HCF in crack propagation are also discussed based on the experimental evidence.

  13. Wooden concrete: High thermal efficiency using waste wood

    SciTech Connect

    Kosny, J.

    1994-09-01

    Wood concrete mixture of wood shavings, lime and cement is widely used in European building construction. In spite of many advantages, this material is almost unknown in the US. Eventual application of wooden concrete in building block production is discussed in this paper. Based on finite difference computer modeling, the thermal performance of several masonry wall systems and their components have been analyzed. The total wall system thermal performance for a typical single-story ranch house also has been determined. At present, typical experimental wall measurements and calculations do not include the effects of building envelope subsystems such as comers, window and door openings, and structural joints with roofs, floors, ceilings, and other walls. In masonry wall systems, these details may represent significant thermal bridges because of the highly conductive structural concrete. Many of the typical thermal bridges may be reduced by application of wood concrete elements.

  14. Thermal stability of high temperature structural alloys

    SciTech Connect

    Jordan, C.E.; Rasefske, R.K.; Castagna, A.

    1999-03-01

    High temperature structural alloys were evaluated for suitability for long term operation at elevated temperatures. The effect of elevated temperature exposure on the microstructure and mechanical properties of a number of alloys was characterized. Fe-based alloys (330 stainless steel, 800H, and mechanically alloyed MA 956), and Ni-based alloys (Hastelloy X, Haynes 230, Alloy 718, and mechanically alloyed MA 758) were evaluated for room temperature tensile and impact toughness properties after exposure at 750 C for 10,000 hours. Of the Fe-based alloys evaluated, 330 stainless steel and 800H showed secondary carbide (M{sub 23}C{sub 6}) precipitation and a corresponding reduction in ductility and toughness as compared to the as-received condition. Within the group of Ni-based alloys tested, Alloy 718 showed the most dramatic structure change as it formed delta phase during 10,000 hours of exposure at 750 C with significant reductions in strength, ductility, and toughness. Haynes 230 and Hastelloy X showed significant M{sub 23}C{sub 6} carbide precipitation and a resulting reduction in ductility and toughness. Haynes 230 was also evaluated after 10,000 hours of exposure at 850, 950, and 1050 C. For the 750--950 C exposures the M{sub 23}C{sub 6} carbides in Haynes 230 coarsened. This resulted in large reductions in impact strength and ductility for the 750, 850 and 950 C specimens. The 1050 C exposure specimens showed the resolution of M{sub 23}C{sub 6} secondary carbides, and mechanical properties similar to the as-received solution annealed condition.

  15. Process for fabricating composite material having high thermal conductivity

    DOEpatents

    Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

    2001-01-01

    A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

  16. Thermal Expansion and Thermophysical Properties of Materials and Minerals at High Temperature and High Pressure

    NASA Astrophysics Data System (ADS)

    Wang, Kai

    1995-11-01

    The knowledge of thermal expansion at high temperature and high pressure is necessary for modeling the equation of the state in the Earth's interior. It is an important parameter for materials science and is critical for understanding the nature of the residual stress in materials. Also, thermal expansion is a factor in the equations that describe many thermoelastic parameters. Errors in thermal expansion will propagate in thermodynamic calculations. This dissertation is based on a semi-empirical, quasi-harmonic, lattice dynamic thermal expansion model, its extension to high temperatures and high pressures and the role of defects on thermal expansion. A modified quasi -harmonic model is proposed to calculate high temperature thermal expansion of alkali halides. An empirical parabolic relationship is found at high temperatures. The contributions of thermal defects at high temperatures are employed to explain the differences between experimental data and the perfect quasi-harmonic crystal model. Expressions for defect contributions on thermal expansion and expansivity are given and applied to obtain the formation energies of thermal defects. Defect ordering is proposed for ionic crystals at high temperatures. A simplified model is derived for predicting high pressure thermal expansion. A detailed expression for defect contributions at high temperatures and high pressures is provided. Thermal expansion of MgO is predicted for pressures as high as at the core-mantle boundary. This model is also applied to alkali halides, and the thermophysical properties of NaCl are given as an example. Then a general model is proposed for evaluating and predicting high temperature thermal expansion. The product of thermal expansion, bulk modulus, and volume, alpha_{V}K_{T }V, or the partial temperature derivative of the work done by thermal pressure, resembles a specific heat curve. A modified Einstein model is applied to express the alpha_{V}K_{T }V data. After assuming a linear

  17. Thermal modelling of various thermal barrier coatings in a high heat flux rocket engine

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.

    1989-01-01

    Traditional Air Plasma Sprayed (APS) ZrO2-Y2O3 Thermal Barrier Coatings (TBC's) and Low Pressure Plasma Sprayed (LPPS) ZrO2-Y2O3/Ni-Cr-Al-Y cermet coatings were tested in a H2/O2 rocked engine. The traditional ZrO2-Y2O3 (TBC's) showed considerable metal temperature reductions during testing in the hydrogen-rich environment. A thermal model was developed to predict the thermal response of the tubes with the various coatings. Good agreement was observed between predicted temperatures and measured temperatures at the inner wall of the tube and in the metal near the coating/metal interface. The thermal model was also used to examine the effect of the differences in the reported values of the thermal conductivity of plasma sprayed ZrO2-Y2O3 ceramic coatings, the effect of 100 micron (0.004 in.) thick metallic bond coat, the effect of tangential heat transfer around the tube, and the effect or radiation from the surface of the ceramic coating. It was shown that for the short duration testing in the rocket engine, the most important of these considerations was the effect of the uncertainty in the thermal conductivity of temperatures (greater than 100 C) predicted in the tube. The thermal model was also used to predict the thermal response of the coated rod in order to quantify the difference in the metal temperatures between the two substrate geometries and to explain the previously-observed increased life of coatings on rods over that on tubes. A thermal model was also developed to predict heat transfer to the leading edge of High Pressure Fuel Turbopump (HPFTP) blades during start-up of the space shuttle main engines. The ability of various TBC's to reduce metal temperatures during the two thermal excursions occurring on start-up was predicted. Temperature reductions of 150 to 470 C were predicted for 165 micron (0.0065 in.) coatings for the greater of the two thermal excursions.

  18. Thermal conductivity and elastic modulus evolution of thermal barrier coatings under high heat flux conditions

    NASA Astrophysics Data System (ADS)

    Zhu, Dongming; Miller, Robert A.

    2000-06-01

    Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may be encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser-simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8% Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m K to 1.15, 1.19, and 1.5 W/m K after 30 h of testing at surface temperatures of 990, 1100, and 1320 °C, respectively, Hardness and elastic modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and microindentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface and to 7.5 GPa at the ceramic coating surface after 120 h of testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced microporosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various TBC applications.

  19. Social Goals, Social Status, and Problem Behavior among Low-Achieving and High-Achieving Adolescents from Rural Schools

    ERIC Educational Resources Information Center

    Ludden, Alison Bryant

    2012-01-01

    The current research examines how social goals and perceptions of what is needed for social status at school relate to school misbehavior and substance use among rural adolescents (N = 683). Results indicate that social goals and perceptions of social status have differential links to problem behaviors depending upon adolescents' achievement.…

  20. Evaluation of English Achievement Test: A Comparison between High and Low Achievers amongst Selected Elementary School Students of Pakistan

    ERIC Educational Resources Information Center

    Haider, Zubair; Latif, Farah; Akhtar, Samina; Mushtaq, Maria

    2012-01-01

    Validity, reliability and item analysis are critical to the process of evaluating the quality of an educational measurement. The present study evaluates the quality of an assessment constructed to measure elementary school student's achievement in English. In this study, the survey model of descriptive research was used as a research method.…

  1. The Relationship between Cognitive and Emotional Intelligence and High School Academic Achievement.

    PubMed

    Matešić, Krunoslav

    2015-06-01

    The study investigated the relationship between intelligence, emotional intelligence and academic achievement in high school. The study was conducted within the standardization of two instruments for Croatian samples. A total of 369 high school students from the Republic of Croatia participated in the study. They completed the Naglieri Nonverbal Ability Test (NNAT)--a test of cognitive intelligence and the BarOn Emotional Quotient Inventory: Youth Version (EQ-i:YV). Academic achievement criteria were general school achievement, Croatian language and mathematics. Several regression analyses were conducted on the results. The results show that cognitive intelligence and the adaptability scale to be consistent predictors of academic achievement. Emotional intelligence was not shown to be a significant predictor of school success. PMID:26753453

  2. Impact of Principal Leadership on Catholic High School Students' Academic Achievement in Edo State, Nigeria

    ERIC Educational Resources Information Center

    Imhangbe, Osayamen Samson

    2012-01-01

    Over the years, students of Catholic High/Senior secondary schools in Edo state, Nigeria have maintained a significantly higher level of academic achievement than their counterparts in public schools in the state. This development has not only been a cause of serious concern for parents of students who attend public High/Senior secondary schools…

  3. The Effects of Guided Inquiry Instruction on Student Achievement in High School Biology

    ERIC Educational Resources Information Center

    Vass, Laszlo

    2010-01-01

    The purpose of this quantitative, quasi-experimental study was to measure the effect of a student-centered instructional method called guided inquiry on the achievement of students in a unit of study in high school biology. The study used a non-random sample of 109 students, the control group of 55 students enrolled in high school one, received…

  4. The Relationship between Self-Efficacy and Achievement in At-Risk High School Students

    ERIC Educational Resources Information Center

    Gold, Jarrett Graham

    2010-01-01

    The focus of this quantitative survey study was the examination of the relationship between self-efficacy and academic achievement in 164 at-risk high school students. The study used Bandura's self-efficacy as the theoretical framework. The research questions involved understanding the levels of self-efficacy in at-risk high school students and…

  5. What Works Clearinghouse Quick Review: "Expanding College Opportunities for High-Achieving, Low Income Students"

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2013

    2013-01-01

    This study examined the effects of providing low-income, high-achieving high school seniors with college application guidance and information about the costs of college. The "application guidance" included information about deadlines and requirements for college applications at nearby institutions, at the state's flagship institution, and at in-…

  6. The Relationship between Thinking Style Differences and Career Choices for High-Achieving Students

    ERIC Educational Resources Information Center

    Kim, Mihyeon

    2011-01-01

    The intent of this study was to present information about high-achieving students' career decision making associated with thinking styles. We gathered data from two International Baccalaureate (IB) programs and a Governor's School Program with a sample of 209 high-school students. The findings of this study demonstrated that the effect of program…

  7. Closing the Mathematics Achievement Gap in High-Poverty Middle Schools: Enablers and Constraints

    ERIC Educational Resources Information Center

    Balfanz, Robert; Byrnes, Vaughan

    2006-01-01

    The mathematics achievement levels of U.S. students fall far behind those of other developed nations; within the United States itself, the students who are falling behind come predominantly from high-poverty and high-minority areas. This article reports on a series of analyses that followed 4 cohorts of students from 3 such schools through the 5th…

  8. Mathematics Achievement with Digital Game-Based Learning in High School Algebra 1 Classes

    ERIC Educational Resources Information Center

    Ferguson, Terri Lynn Kurley

    2014-01-01

    This study examined the impact of digital game-based learning (DGBL) on mathematics achievement in a rural high school setting in North Carolina. A causal comparative research design was used in this study to collect data to determine the effectiveness of DGBL in high school Algebra 1 classes. Data were collected from the North Carolina…

  9. Urban Students Achieve When High Schools Implement Proven Practices. Research Brief

    ERIC Educational Resources Information Center

    Bottoms, Gene; Han, Lingling; Presson, Alice

    2006-01-01

    Students benefit from a year or more gain in student achievement when urban district and high school leaders commit to the implementation of the "High Schools That Work" ("HSTW") design. It is not enough to be a "HSTW" site--it is about taking effective actions to implement the design. Schools that do take action witness significant progress in…

  10. The Effects of Modeling Instruction on High School Physics Academic Achievement

    ERIC Educational Resources Information Center

    Wright, Tiffanie L.

    2012-01-01

    The purpose of this study was to explore whether Modeling Instruction, compared to traditional lecturing, is an effective instructional method to promote academic achievement in selected high school physics classes at a rural middle Tennessee high school. This study used an "ex post facto," quasi-experimental research methodology. The…

  11. School Context, Precollege Educational Opportunities, and College Degree Attainment among High-Achieving Black Males

    ERIC Educational Resources Information Center

    Rose, Valija C.

    2013-01-01

    Access to high-quality educational opportunities is central to growing postsecondary degree attainment. This study employs secondary data analysis of the public-use National Education Longitudinal Study (NELS:88/00) to examine how school context and precollege educational opportunities influence college degree attainment among high-achieving Black…

  12. Study-Orientation of High and Low Academic Achievers at Secondary Level in Pakistan

    ERIC Educational Resources Information Center

    Sarwar, Muhammad; Bashir, Muhammad; Khan, Muhammad Naemullah; Khan, Muhammad Saeed

    2009-01-01

    The study orientation of low and high academic achievers was compared, measured through a self-developed study orientation scale (SOS) primarily based on 47 items comparing study habits and attitude. Students' marks obtained in the 10th grade Examination determined the measure of academic performance. The analysis revealed that the high achievers…

  13. The Relationship between Principals' Instructional Focus and Academic Achievement of High Poverty Students

    ERIC Educational Resources Information Center

    Aste, Mahri

    2009-01-01

    The purpose of the study was to determine the relationship between teacher perceptions of the frequency and effectiveness of principal instructional leadership behaviors and student achievement in high-poverty elementary schools. In order to accomplish the purpose, survey methodology was employed. Teachers from six high-poverty elementary schools…

  14. Small Classes in the Early Grades, Academic Achievement, and Graduating From High School

    ERIC Educational Resources Information Center

    Finn, Jeremy D.; Gerber, Susan B.; Boyd-Zaharias, Jayne

    2005-01-01

    This investigation addressed 3 questions about the long-term effects of early school experiences: (a) Is participation in small classes in the early grades (K-3) related to high school graduation? (b) Is academic achievement in K-3 related to high school graduation? (c) If class size is related to graduation, is the relationship explained by the…

  15. Causes of Nonattendance and Its Effect on Student Achievement at the High School Level

    ERIC Educational Resources Information Center

    Bracht, Kelly D.

    2010-01-01

    Many high schools in America have issues with student nonattendance. The researcher designed this mixed methods study to determine the affect of nonattendance on student achievement and to ascertain whether home-related factors or school-related factors were more significant causes of nonattendance. Both the high school in this study and other…

  16. Improving High School Students' Mathematics Achievement through the Use of Motivational Strategies.

    ERIC Educational Resources Information Center

    Portal, Jamie; Sampson, Lisa

    This report describes a program for motivating students in mathematics in order to improve achievement at the high school level. The targeted population consisted of high school students in a middle class community located in a suburb of a large metropolitan area. The problems of underachievement were documented through data collected from surveys…

  17. Emotional Intelligence as a Predictor of Leadership of Kuwaiti High and Low Achieving 11th Graders

    ERIC Educational Resources Information Center

    Alnabhan, Mousa

    2010-01-01

    The current study examined the association between emotional intelligence (EI) and the Leadership components (L) of high school students in the state of Kuwait. The possibility of predicting each leadership component via emotional intelligence components was investigated for high and low achievers. A sample of 11th grade students from Kuwaiti…

  18. The Contribution of Limbic Learning Aptitude to Achievement in High School. Final Report.

    ERIC Educational Resources Information Center

    Ax, Albert F.; And Others

    Achievement in earning grades in high school was resolved into its intellectual and motivational components. This study employed tests of I.Q., personality inventories and classical and operant conditioning of autonomic nervous system controlled variables. Eleven procedures were given to 99 Black inner city high school seniors. Six physiological…

  19. A Case Study of 21st Century Skills in High Achieving Elementary Schools in Pennsylvania

    ERIC Educational Resources Information Center

    Egnor, Gregory P.

    2013-01-01

    This study examines if practices that advocate for 21st century skills are in conflict with the mandates of NCLB. Interviews with influential school leaders of high achieving elementary schools focused on collecting data about 21st century skills. This study was designed to (a) Determine if 21st century skills are addressed in high achieving…

  20. Modeling thermally driven energetic response of high explosives

    SciTech Connect

    Sharp, R; Couch, R; McCallen, R C; Nichols III, A L; Otero, I

    1998-02-01

    We have improved our ability to model the response of energetic materials to thermal stimuli and the processes involved in the energetic response. Traditionally, the analyses of energetic materials have involved coupled thermal transport/chemical reaction codes. This provides only a reasonable estimate of the time and location of ensuing rapid reaction. To predict the violence of the reaction, the mechanical motion must be included in the wide range of time scales associated with the thermal hazard. The ALE3D code has been modified to assess the hazards associated with heating energetic materials in weapons by coupling to thermal transport model and chemistry models. We have developed an implicit time step option to efficiently and accurately compute the hours of heating to reaction of the energetic material. Since, on these longer time scales materials can be expected to have significant motion, it is even more important to provide high-order advection for all components, including the chemical species. We show two examples of coupled thermal/mechanical/chemical models of energetic materials in thermal environments.

  1. Modeling thermally driven energetic response of high explosives

    SciTech Connect

    Couch, R; McCallen, R C; Nichols III, A L; Otero, I; Sharp, R

    1998-08-17

    We have improved our ability to model the response of energetic materials to thermal stimuli and the processes involved in the energetic response. Traditionally, the analyses of energetic materials have involved coupled thermal transport/chemical reaction codes. This provides only a reasonable estimate of the time and location of ensuing rapid reaction. To predict the violence of the reaction, the mechanical motion must be included in the wide range of time scales associated with the thermal hazard. The ALE3D code has been modified to assess the hazards associated with heating energetic materials in weapons by coupling to thermal transport model and chemistry models. We have developed an implicit time step option to efficiently and accurately compute the hours of heating to reaction of the energetic material. Since, on these longer time scales materials can be expected to have significant motion, it is even more important to provide high-order advection for all components, including the chemical species. We show two examples of coupled thermal/mechanical/chemical models of energetic materials in thermal environments.

  2. Thermal design concept for a high resolution UV spectrometer

    NASA Technical Reports Server (NTRS)

    Caruso, P.; Stipandic, E.

    1979-01-01

    The thermal design concept described has been developed for the High Resolution UV Spectrometer/Polarimeter to be flown on the Solar Maximum Mission. Based on experience gained from a similar Orbiting Solar Observatory mission payload, it has been recognized that initial protection of the optical elements, contamination control, reduction of scattered light, tight bulk temperature, and gradient constraints are key elements that must be accommodated in any thermal control concept for this class of instrument. Salient features of the design include: (1) a telescope door providing contamination protection of an aplanatic Gregorian telescope; (2) a rastering system for the secondary mirror; (3) a unique solar heat absorbing device; (4) heat pipes and special radiators; (5) heaters for active temperature control and optics contamination protection; and (6) high precision platinum resistance thermometers. Viability of the design concept has been established by extensive thermal analysis and some subsystem testing. A summary of analytical and test results is included.

  3. High Resolution Viscosity Measurement by Thermal Noise Detection

    PubMed Central

    Aguilar Sandoval, Felipe; Sepúlveda, Manuel; Bellon, Ludovic; Melo, Francisco

    2015-01-01

    An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD) of thermal fluctuations together with Sader’s model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0.03 mPa·s was detected with the alternative to achieve measurements with a volume as low as 50 μL. PMID:26540061

  4. High Resolution Viscosity Measurement by Thermal Noise Detection.

    PubMed

    Sandoval, Felipe Aguilar; Sepúlveda, Manuel; Bellon, Ludovic; Melo, Francisco

    2015-01-01

    An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD) of thermal fluctuations together with Sader's model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0:03mPa·s was detected with the alternative to achieve measurements with a volume as low as 50 µL. PMID:26540061

  5. Academic achievement and career choice in science: Perceptions of African American urban high school students

    NASA Astrophysics Data System (ADS)

    Jones, Sheila Kay

    2007-12-01

    Low test scores in science and fewer career choices in science among African American high school students than their White counterparts has resulted in lower interest during high school and an underrepresentation of African Americans in science and engineering fields. Reasons for this underachievement are not known. This qualitative study used a grounded theory methodology to examine what influence parental involvement, ethnic identity, and early mentoring had on the academic achievement in science and career choice in science of African American urban high school 10th grade students. Using semi-structured open-ended questions in individual interviews and focus groups, twenty participants responded to questions about African American urban high school student achievement in science and their career choice in science. The median age of participants was 15 years; 85% had passed either high school biology or physical science. The findings of the study revealed influences and interactions of selected factors on African American urban high school achievement in science. Sensing potential emerged as the overarching theme with six subthemes; A Taste of Knowledge, Sounds I Hear, Aromatic Barriers, What Others See, The Touch of Others, and The Sixth Sense. These themes correlate to the natural senses of the human body. A disconnect between what science is, their own individual learning and success, and what their participation in science could mean for them and the future of the larger society. Insight into appropriate intervention strategies to improve African American urban high school achievement in science was gained.

  6. Factors That Influence School Board Actions to Support Student Achievement: A Multi-Case Study of High-Achieving Rural School Districts

    ERIC Educational Resources Information Center

    Timm, Colleen A.

    2012-01-01

    The purpose of this study is to examine the factors that influence the actions taken by school boards that advance student achievement in high-achieving rural public school districts. Much of what is discussed in the literature on school improvement efforts is centered on the work carried out by school personnel at the school level. What is…

  7. The Impact of Including Children with Intellectual Disability in General Education Classrooms on the Academic Achievement of Their Low-, Average-, and High-Achieving Peers

    ERIC Educational Resources Information Center

    Sermier Dessemontet, Rachel; Bless, Gerard

    2013-01-01

    Background: This study aimed at assessing the impact of including children with intellectual disability (ID) in general education classrooms with support on the academic achievement of their low-, average-, and high-achieving peers without disability. Method: A quasi-experimental study was conducted with an experimental group of 202 pupils from…

  8. Does Homogeneous Ability Grouping for High School Honors English Instruction Benefit the High Achiever?

    ERIC Educational Resources Information Center

    Hostetter, Douglas Paul

    2013-01-01

    Public schools are examining their policies and instructional practices to address the achievement gap exposed by the reporting requirements of NCLB (Wenglinski, 2004). As accountability measures and stakes rise, there is a call for an improved use of scientific evidence to inform educational policymaking (Wiseman, 2010). In terms of the…

  9. High-temperature molten salt thermal energy storage systems

    NASA Technical Reports Server (NTRS)

    Petri, R. J.; Claar, T. D.; Tison, R. R.; Marianowski, L. G.

    1980-01-01

    The results of comparative screening studies of candidate molten carbonate salts as phase change materials (PCM) for advanced solar thermal energy storage applications at 540 to 870 C (1004 to 1600 F) and steam Rankine electric generation at 400 to 540 C (752 to 1004 F) are presented. Alkali carbonates are attractive as latent heat storage materials because of their relatively high storage capacity and thermal conductivity, low corrosivity, moderate cost, and safe and simple handling requirements. Salts were tested in 0.1 kWhr lab scale modules and evaluated on the basis of discharge heat flux, solidification temperature range, thermal cycling stability, and compatibility with containment materials. The feasibility of using a distributed network of high conductivity material to increase the heat flux through the layer of solidified salt was evaluated. The thermal performance of an 8 kWhr thermal energy storage (TES) module containing LiKCO3 remained very stable throughout 5650 hours and 130 charge/discharge cycles at 480 to 535 C (896 to 995 F). A TES utilization concept of an electrical generation peaking subsystem composed of a multistage condensing steam turbine and a TES subsystem with a separate power conversion loop was defined. Conceptual designs for a 100 MW sub e TES peaking system providing steam at 316 C, 427 C, and 454 C (600 F, 800 F, and 850 F) at 3.79 million Pa (550 psia) were developed and evaluated. Areas requiring further investigation have also been identified.

  10. Effects of a Collaborative Science Intervention on High Achieving Students' Learning Anxiety and Attitudes toward Science

    NASA Astrophysics Data System (ADS)

    Hong, Zuway-R.

    2010-10-01

    This study investigated the effects of a collaborative science intervention on high achieving students' learning anxiety and attitudes toward science. Thirty-seven eighth-grade high achieving students (16 boys and 21 girls) were selected as an experimental group who joined a 20-week collaborative science intervention, which integrated and utilized an innovative teaching strategy. Fifty-eight eighth-grade high achieving students were selected as the comparison group. The Secondary School Student Questionnaire was conducted to measure all participants' learning anxiety and attitudes toward science. In addition, 12 target students from the experimental group (i.e., six active and six passive students) were recruited for weekly classroom observations and follow-up interviews during the intervention. Both quantitative and qualitative findings revealed that experimental group students experienced significant impact as seen through increased attitudes and decreased anxiety of learning science. Implications for practice and research are provided.

  11. Sintering Characteristics of Multilayered Thermal Barrier Coatings Under Thermal Gradient and Isothermal High Temperature Annealing Conditions

    NASA Technical Reports Server (NTRS)

    Rai, Amarendra K.; Schmitt, Michael P.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    Pyrochlore oxides have most of the relevant attributes for use as next generation thermal barrier coatings such as phase stability, low sintering kinetics and low thermal conductivity. One of the issues with the pyrochlore oxides is their lower toughness and therefore higher erosion rate compared to the current state-of-the-art TBC material, yttria (6 to 8 wt%) stabilized zirconia (YSZ). In this work, sintering characteristics were investigated for novel multilayered coating consisted of alternating layers of pyrochlore oxide viz Gd2Zr2O7 and t' low k (rare earth oxide doped YSZ). Thermal gradient and isothermal high temperature (1316 C) annealing conditions were used to investigate sintering and cracking in these coatings. The results are then compared with that of relevant monolayered coatings and a baseline YSZ coating.

  12. School factors affecting postsecondary career pursuits of high-achieving girls in mathematics and science

    NASA Astrophysics Data System (ADS)

    Yoo, Hyunsil

    This study examined the influences of secondary school experiences of high-achieving girls in math and science on their postsecondary career pursuits in science fields. Specifically, using the National Education Longitudinal Study of 1988 (NELS:88), the study investigated how science class experiences in high school affect science career persistence of high-achieving girls over and above personal and family factors. Selecting the top 10% on the 8 th grade math and science achievement tests from two panel samples of 1988--1994 and 1988--2000, this study examined which science instructional experiences (i.e., lecture-oriented, experiment-oriented, and student-oriented) best predicted college major choices and postsecondary degree attainments in the fields of science after controlling for personal and family factors. A two-stage test was employed for the analysis of each panel sample. The first test examined the dichotomous career pursuits between science careers and non-science careers and the second test examined the dichotomous pursuits within science careers: "hard" science and "soft" science. Logistic regression procedures were used with consideration of panel weights and design effects. This study identified that experiment-oriented and student-oriented instructional practices seem to positively affect science career pursuits of high-achieving females, while lecture-oriented instruction negatively affected their science career pursuits, and that the longitudinal effects of the two positive instructional contributors to science career pursuits appear to be differential between major choice and degree attainment. This study also found that the influences of instructional practices seem to be slight for general females, while those for high-achieving females were highly considerable, regardless of whether negative or positive. Another result of the study found that only student-oriented instruction seemed to have positive effects for high-achieving males. In

  13. Long-duration thermal storage for solar-thermal high-pressure steam IPH

    SciTech Connect

    Copeland, R.J.; Stern, C.; Leach, J.W.

    1982-12-01

    Solar-thermal central-receiver systems are cost effective for electric-power and industrial process-heat applications. Systems employing molten nitrate salt as both receiver working fluid and storage have previously been evaluated for diurnal thermal storage. This study evaluates the potential of employing a molten salt receiver for a baseload industrial process plant requiring saturated steam at 68 atm (1000 psi). Two types of thermal storage are evaluated: molten salt, and air and rock. When thermal storage of six hours or less is used, molten nitrate salt alone is the optimum storage. For more than six hours, the optimum storage is a combination of molten salt and air and rock. The air and rock system uses a molten-salt-to-air heat exchanger and a thermocline rock bed heated and cooled by the air. The economic potential of the system is determined. The results depend on the relative cost of fossil fuel and the solar thermal energy costs. The optimum quantity of storage is highly variable, and the range is from no storage to a long duration capacity - 48 hours.

  14. High-Flux, High-Temperature Thermal Vacuum Qualification Testing of a Solar Receiver Aperture Shield

    NASA Technical Reports Server (NTRS)

    Kerslake, Thomas W.; Mason, Lee S.; Strumpf, Hal J.

    1997-01-01

    As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LERC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world's first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal Multi-Foil Insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near

  15. High-flux, high-temperature thermal vacuum qualification testing of a solar receiver aperture shield

    SciTech Connect

    Kerslake, T.W.; Mason, L.S.; Strumpf, H.J.

    1997-12-31

    As part of the International Space Station (ISS) Phase 1 program, NASA Lewis Research Center (LeRC) and the Russian Space Agency (RSA) teamed together to design, build and flight test the world`s first orbital Solar Dynamic Power System (SDPS) on the Russian space station Mir. The Solar Dynamic Flight Demonstration (SDFD) program was to operate a nominal 2 kWe SDPS on Mir for a period up to 1-year starting in late 1997. Unfortunately, the SDFD mission was demanifested from the ISS Phase 1 shuttle program in early 1996. However, substantial flight hardware and prototypical flight hardware was built including a heat receiver and aperture shield. The aperture shield comprises the front face of the cylindrical cavity heat receiver and is located at the focal plane of the solar concentrator. It is constructed of a stainless steel plate with a 1-m outside diameter, a 0.24-m inside diameter and covered with high-temperature, refractory metal multi-foil insulation (MFI). The aperture shield must minimize heat loss from the receiver cavity, provide a stiff, high strength structure to accommodate shuttle launch loads and protect receiver structures from highly concentrated solar fluxes during concentrator off-pointing events. To satisfy Mir operational safety protocols, the aperture shield was required to accommodate direct impingement of the intensely concentrated solar image for a 1-hour period. To verify thermal-structural durability under the anticipated high-flux, high-temperature loading, an aperture shield test article was constructed and underwent a series of two tests in a large thermal vacuum chamber configured with a reflective, point-focus solar concentrator and a solar simulator. The test article was positioned near the focal plane and exposed to concentrated solar flux for a period of 1-hour. In the first test, a near equilibrium temperature of 1862 K was attained in the center of the shield hot spot. In the second test, with increased incident flux, a near

  16. Glass ceramics for sealing to high-thermal-expansion metals

    SciTech Connect

    Wilder, Jr., J. A.

    1980-10-01

    Glass ceramics were studied, formulated in the Na/sub 2/O CaO.P/sub 2/O/sub 5/, Na/sub 2/O.BaOP/sub 2/O/sub 5/, Na/sub 2/O.Al/sub 2/O/sub 3/.P/sub 2/O/sub 5/, and Li/sub 2/O.BaO.P/sub 2/O/sub 5/ systems to establish their suitability for sealing to high thermal expansion metals, e.g. aluminum, copper, and 300 series stainless steels. Glass ceramics in Na/sub 2/O.CaO.P/sub 2/O/sub 5/ and Na/sub 2/O.BaO.P/sub 2/O/sub 5/ systems have coefficients of thermal expansion in the range 140 x 10/sup -1/ per /sup 0/C less than or equal to ..cap alpha.. less than or equal to 225 x 10/sup -7/ per /sup 0/C and fracture toughness values generally greater than those of phosphate glasses; they are suitable for fabricating seals to high thermal expansion metals. Crystal phases include NaPo/sub 3/, (NaPO/sub 3/)/sub 3/, NaBa(PO/sub 3/)/sub 3/, and NaCa(PO/sub 3/)/sub 3/. Glass ceramics formed in the Na/sub 2/O.Al/sub 2/O/sub 3/.P/sub 2/O/sub 5/ systems have coefficients of thermal expansion greater than 240 x 10/sup -7/ per /sup 0/C, but they have extensive microcracking. Due to their low thermal expansion values (..cap alpha.. less than or equal to 120 x 10/sup -7/ per /sup 0/C), glass ceramics in the Li/sub 2/O.BaO.P/sub 2/O/sub 5/ system are unsuitable for sealing to high thermal expansion metals.

  17. Analysis of Thermal Expansivity of Solids Under High Pressures

    NASA Astrophysics Data System (ADS)

    Sunil, K.; Singh, P. K.; Sharma, B. S.

    2012-08-01

    For investigating the thermal expansivity of solids under high pressures we have developed a formulation using the relationship between the reciprocal of pressure derivative of bulk modulus and the ratio of pressure and bulk modulus. The formulation presented here satisfies the boundary conditions both at zero-pressure and also in the limit of infinite pressure at extreme compression. A physically acceptable relationship has been obtained between the Anderson-Grüneisen parameter and the pressure derivatives of bulk modulus. The formulation has been applied to determine the pressure dependence of thermal expansivity of NaCl, MgO and the earth lower mantle minerals.

  18. Thermal performance of windows having high solar transmittance

    SciTech Connect

    Rubin, M.; Selkowitz, S.

    1981-07-01

    Antireflected polyester films and low-iron glass sheets have values of solar transmittance that are substantially higher than those of their untreated counterparts. The plastic films utilize coatings to reduce loses due to surface reflectance and the glass is made with low levels of impurities to reduce adsorption within the material itself. The optical and thermal properties of these materials are discussed and the solar and thermal characteristics of windows incorporating high-transmittance glazing layers are derived. Comparisons among these and other types of windows are made on the basis of net energy use for residential buildings in winter.

  19. Thermal management system options for high power space platforms

    NASA Technical Reports Server (NTRS)

    Sadunas, J. A.; Lehtinen, A.; Parish, R.

    1985-01-01

    Thermal Management System (TMS) design options for a high power (75kWe), low earth orbit, multimodule space platform were investigated. The approach taken was to establish a baseline TMS representative of current technology, and to make incremental improvements through successive subsystem trades that lead to a candidate TMS. The TMS trades included centralized and decentralized transport, single-phase and two-phase transport, alternate working fluids, liquid loop and heat pipe radiators, deployed fixed, body mounted and steerable radiators, and thermal storage. The subsystem options were evaluated against criteria such as weight, TMS power requirement, reliability, system isothermality penalty, and growth potential.

  20. High temperature underground thermal energy storage system for solar energy

    NASA Technical Reports Server (NTRS)

    Collins, R. E.

    1980-01-01

    The activities feasibility of high temperature underground thermal storage of energy was investigated. Results indicate that salt cavern storage of hot oil is both technically and economically feasible as a method of storing huge quantities of heat at relatively low cost. One particular system identified utilizes a gravel filled cavern leached within a salt dome. Thermal losses are shown to be less than one percent of cyclically transferred heat. A system like this having a 40 MW sub t transfer rate capability and over eight hours of storage capacity is shown to cost about $13.50 per KWh sub t.

  1. Obtaining high thermally conductive materials by pressing from the granulate

    NASA Astrophysics Data System (ADS)

    Ditts, A.; Revva, I.; Pautova, Y.; Pogrebenkov, V.; Nepochatov, Y.; Galashov, E.; Tarnovskiy, R.

    2015-01-01

    This work contains results of investigation of obtaining high thermally conductive ceramics from commercial powders of aluminum nitride and yttrium oxide by the method of monoaxial compaction of granulate. The principal scheme of preparation is proposed and technological properties of granulate are defined. Compaction conditions for simple items to use as heat removal in microelectronics and power electrical engineering have been established. Investigations of thermophysical properties of obtained ceramics and its structure by the XRD and SEM methods have been carried out. Ceramics with thermal conductivity from 172 to 174 W/m·K has been obtained as result of this work.

  2. Electromagnetic inhibition of high frequency thermal bonding machine

    NASA Astrophysics Data System (ADS)

    He, Hong; Zhang, Qing-qing; Li, Hang; Zhang, Da-jian; Hou, Ming-feng; Zhu, Xian-wei

    2011-12-01

    The traditional high frequency thermal bonding machine had serious radiation problems at dominant frequency, two times frequency and three times frequency. Combining with its working principle, the problems of electromagnetic compatibility were studied, three following measures were adopted: 1.At the head part of the high frequency thermal bonding machine, resonant circuit attenuator was designed. The notch groove and reaction field can make the radiation being undermined or absorbed; 2.The electromagnetic radiation shielding was made for the high frequency copper power feeder; 3.Redesigned the high-frequency oscillator circuit to reduce the output of harmonic oscillator. The test results showed that these measures can make the output according with the national standard of electromagnetic compatibility (GB4824-2004-2A), the problems of electromagnetic radiation leakage can be solved, and good social, environmental and economic benefits would be brought.

  3. Directional solidification at ultra-high thermal gradient

    NASA Technical Reports Server (NTRS)

    Flemings, M. C.; Lee, D. S.; Neff, M. A.

    1980-01-01

    A high gradient controlled solidification (HGC) furnace was designed and operated at gradients up to 1800 C/cm to continuously produce aluminum alloys. Rubber '0' rings for the water cooling chamber were eliminated, while still maintaining water cooling directly onto the solidified metal. An HGC unit for high temperature ferrous alloys was also designed. Successful runs were made with cast iron, at thermal gradients up to 500 C/cm.

  4. High-efficiency photonic crystal narrowband thermal emitters

    NASA Astrophysics Data System (ADS)

    Farfan, G. B.; Su, M. F.; Reda Taha, M. M.; El-Kady, I.

    2010-02-01

    Photonic crystals (PhC) are artificial structures fabricated with a periodicity in the dielectric function. This periodic electromagnetic potential results in creation of energy bandgaps where photon propagation is prohibited. PhC structures have promising use in thermal applications if optimized to operate at specific thermal emission spectrum. Here, novel utilization of optimized PhC's in thermal applications is presented. We demonstrate through numerical simulation the modification of the thermal emission spectrum by a metallic photonic crystal (PhC) to create high-efficiency multispectral thermal emitters. These emitters funnel radiation from a broad emission spectrum associated with a Plancklike distribution into a prescribed narrow emission band. A detailed quantitative evaluation of the spectral and power efficiencies of a PhC thermal emitter and its portability across infrared (IR) spectral bands are provided. We show an optimized tungsten PhC with a predominant narrow-band emission profile with an emitter efficiency that is more than double that of an ideal blackbody and ~65-75% more power-efficiency across the IR spectrum. We also report on using optimal three-dimensional Lincoln log photonic crystal (LL-PhC) emitters for thermophotovoltaic (TPV) generation as opposed to using a passive filtering approach to truncate the broadband thermal source emission to match the bandgap of a photovoltaic (PV) cell. The emitter performance is optimized for the 1-2μm PV band using different PhC materials, specifically copper, silver and gold. The use of the proposed PhC in TPV devices can produce significant energy savings not reported before. The optimal design of the PhC geometry is obtained by implementing a variety of optimization methods integrated with artificial intelligence (AI) algorithms.

  5. High conductivity, low cost aluminum composite for thermal management

    SciTech Connect

    Sommer, J.L.

    1997-04-01

    In order to produce an inexpensive packaging material that exhibits high thermal conductivity and low CTE, Technical Research Associates, Inc. (TRA) has shown in Phase I the feasibility of incorporating natural flake graphite in an aluminum matrix. TRA has developed a proprietary coating technique where graphite flakes have been coated with a thin layer of molybdenum/molybdenum carbide (approximately 0.2 microns). This barrier coating can protect the graphite flake from chemical reaction and high temperature degradation in molten aluminum silicon alloys. Methods to successfully vacuum infiltrate coated flake with molten aluminum alloys were developed. The resulted metal matrix composites exhibited lower CTE than aluminum metal. The CTE of the composites were significantly lower than aluminum and its alloys. The CTE can potentially be tailored for specific applications. The in plane thermal conductivity was higher than the aluminum matrix alloy. The thermal conductivity and CTE of the composite may be significantly improved by improving the bond strength of the molybdenum coating on the graphite flake. The flake can potentially be incorporated in the molten aluminum and pressure die cast to align the flakes within the aluminum matrix. By preferentially aligning high conductivity graphite flakes within a plane or direction, the thermal conductivity of the resulting composite will be above pure aluminum in the alignment direction.

  6. Organic underlayer materials with exceptionally high thermal stability

    NASA Astrophysics Data System (ADS)

    Cheon, Hwan-Sung; Yoon, Kyong-Ho; Kim, Min-Soo; Oh, Sung Bae; Song, Jee-Yun; Tokareva, Nataliya; Kim, Jong-Seob; Chang, Tuwon

    2009-03-01

    Multilayer hardmask (MLHM) schemes have been implemented as an indispensable process for ArF lithography which continues to demand thinner photoresist films. There are many variations of MLHM and semiconductor manufacturers choose to adopt their own designs, depending on their specific needs and technical advances. The quad-layer stack consisting of photoresist, organic ARC, CVD Si hardmask, and spin-on carbon underlayer is one of them. Despite the need for wafer transporting between the spin track and CVD equipment, this scheme is attractive because it can avoid laborious elaboration of sophisticated etching chemistries for spin-on Si-ARC and carbon underlayer. One of the issues arising from the mixed film forming process is the thermal stability of carbon underlayer at high temperatures during the CVD process of the Si hardmask. Organic underlayer which shows high thermal stability is crucial for this mixed hardmask process. These types of thermally stable organic film can also be used for other applications such as the spacer patterning technique for pitch size shrinkage. In this paper, we discuss the development of organic resins with high thermal stability, their physical properties, and their lithographic behaviors in the MLHM schemes.

  7. Applications of heat pipes for high thermal load beam lines

    SciTech Connect

    Shu, D.; Mortazavi, P.; Rarback, H.; Howells, M.R.

    1985-01-01

    The high flux beam produced by insertion devices often requires special heat removal techniques. For the optical elements used in such high thermal load beam lines, the required precision demands a highly accurate design. Heat pipe cooling of critical elements of the X-1 beam line at the National Synchrotron Light Source is described. This method reduces vibrations caused by water cooling systems and simplifies the design. In some of these designs, deposited heat must be transferred through unbonded contact interfaces. A pinhole assembly and a beam position monitor designed for the X-1 beam line both transfer heat through such interfaces in an ultrahigh vacuum environment. The fundamental design objective is that of removing the heat with minimal interface thermal resistance. We present our test method and results for measuring the thermal resistance across metallic interfaces as a function of contact pressure. The design of some devices which utilize both heat pipes and thermal contact interfaces will also be described. 12 refs., 8 figs.

  8. Thermal lensing compensation optics for high power lasers

    NASA Astrophysics Data System (ADS)

    Scaggs, Michael; Haas, Gil

    2011-03-01

    Athermalization of focusing objectives is a common technique for optimizing imaging systems in the infrared where thermal effects are a major concern. The athermalization is generally done within the spectrum of interest and not generally applied to a single wavelength. The predominate glass used with high power infrared lasers in the near infrared of one micron, such as Nd:YAG and fiber lasers, is fused silica which has excellent thermal properties. All glasses, however, have a temperature coefficient of index of refraction (dn/dT) where as the glass heats up its index of refraction changes. Most glasses, fused silica included, have a positive dn/dT. A positive dn/dT will cause the focal length of the lens to decrease with a temperature rise. Many of the fluoride glasses, like CaF2, BaF2, LiF2, etc. have a negative dn/dT. By applying athermalization techniques of glass selection and optical design, the thermal lensing in a laser objective of a high power laser system can be substantially mitigated. We describe a passive method for minimizing thermal lensing of high power laser optics.

  9. High-field thermal transport properties of REBCO coated conductors

    NASA Astrophysics Data System (ADS)

    Bonura, Marco; Senatore, Carmine

    2015-02-01

    The use of REBCO coated conductors (CCs) is envisaged for many applications, extending from power cables to high-field magnets. Whatever the case, thermal properties of REBCO tapes play a key role for the stability of superconducting devices. In this work, we present the first study on the longitudinal thermal conductivity (κ) of REBCO CCs in magnetic fields up to 19 T applied both parallel and perpendicularly to the thermal-current direction. Copper-stabilized tapes from six industrial manufacturers have been investigated. We show that zero-field κ of CCs can be calculated with an accuracy of +/- 15% from the residual resistivity ratio of the stabilizer and the Cu/non-Cu ratio. Measurements performed at high fields have allowed us to evaluate the consistency of the procedures generally used for estimating in-field κ in the framework of the Wiedemann-Franz law from an electrical characterization of the materials. In-field data are intended to provide primary ingredients for the thermal stability analysis of high-temperature superconductor-based magnets.

  10. IMPULSE---an advanced, high performance nuclear thermal propulsion system

    SciTech Connect

    Petrosky, L.J.; Disney, R.K.; Mangus, J.D. ); Gunn, S.A.; Zweig, H.R. )

    1993-01-10

    IMPULSE is an advanced nuclear propulsion engine for future space missions based on a novel conical fuel. Fuel assemblies are formed by stacking a series of truncated (U, Zr)C cones with non-fueled lips. Hydrogen flows radially inward between the cones to a central plenum connected to a high performance bell nozzle. The reference IMPULSE engine rated at 75,000 lb thrust and 1800 MWt weighs 1360 kg and is 3.65 meters in height and 81 cm in diameter. Specific impulse is estimated to be 1000 for a 15 minute life at full power. If longer life times are required, the operating temperature can be reduced with a concomitant decrease in specific impulse. Advantages of this concept include: well defined coolant paths without outlet flow restrictions; redundant orificing; very low thermal gradients and hence, thermal stresses, across the fuel elements; and reduced thermal stresses because of the truncated conical shape of the fuel elements.

  11. Antioxidant-Based Phase-Change Thermal Interface Materials with High Thermal Stability

    NASA Astrophysics Data System (ADS)

    Aoyagi, Yasuhiro; Chung, D. D. L.

    2008-04-01

    This work provides phase-change thermal interface materials (TIMs) with high thermal stability and high heat of fusion. They are based on antioxidants mainly in the form of hydrocarbons with linear segments. The thermal stability is superior to paraffin wax and four commercial phase-change materials (PCMs). The use of 98.0 wt.% thiopropionate antioxidant (SUMILIZER TP-D) with 2.0 wt.% sterically half-hindered phenolic antioxidant (GA80) as the matrix and the use of 16 vol.% boron nitride particles as the solid component give a PCM with a 100°C lifetime indicator of 5.3 years, in contrast to 0.95 year or less for the commercial PCMs. The heat of fusion is much higher than those of commercial PCMs; the values for antioxidants with nonbranched molecular structures exceed that of wax; the value for one with a branched structure is slightly below that of wax. The phase-change properties are degraded by heating at 150°C much less than those of the commercial PCMs. The stability of the heat of fusion upon phase-change cycling is also superior. The viscosity is essentially unaffected by heating at 150°C. Commercial PCMs give slightly lower values of the thermal contact conductance for the case of rough (12 μm) mating surfaces, in spite of the lower values of the bond-line thickness.

  12. Following Different Pathways: Social Integration, Achievement, and the Transition to High School.

    PubMed

    Langenkamp, Amy G

    2009-11-01

    This study expands research on an academic and social turning point for adolescents, the transition to high school, by analyzing how students' level of social integration into school can affect high school academic performance. Using nationally representative data, three different pathways emerged as students transition to high school, characterized by varying amounts of disruption and opportunity for new social relationships upon entering high school. Findings suggest that elements of middle school social integration, including teacher bonding, popularity, and extracurricular participation, affect academic achievement when students enter high school. However, the association between integration into school and academic performance appears to be contingent upon the pathway students follow. PMID:20664813

  13. Following Different Pathways: Social Integration, Achievement, and the Transition to High School

    PubMed Central

    LANGENKAMP, AMY G.

    2010-01-01

    This study expands research on an academic and social turning point for adolescents, the transition to high school, by analyzing how students’ level of social integration into school can affect high school academic performance. Using nationally representative data, three different pathways emerged as students transition to high school, characterized by varying amounts of disruption and opportunity for new social relationships upon entering high school. Findings suggest that elements of middle school social integration, including teacher bonding, popularity, and extracurricular participation, affect academic achievement when students enter high school. However, the association between integration into school and academic performance appears to be contingent upon the pathway students follow. PMID:20664813

  14. High thermal conductivity of chain-oriented amorphous polythiophene.

    PubMed

    Singh, Virendra; Bougher, Thomas L; Weathers, Annie; Cai, Ye; Bi, Kedong; Pettes, Michael T; McMenamin, Sally A; Lv, Wei; Resler, Daniel P; Gattuso, Todd R; Altman, David H; Sandhage, Kenneth H; Shi, Li; Henry, Asegun; Cola, Baratunde A

    2014-05-01

    Polymers are usually considered thermal insulators, because the amorphous arrangement of the molecular chains reduces the mean free path of heat-conducting phonons. The most common method to increase thermal conductivity is to draw polymeric fibres, which increases chain alignment and crystallinity, but creates a material that currently has limited thermal applications. Here we show that pure polythiophene nanofibres can have a thermal conductivity up to ∼ 4.4 W m(-1) K(-1) (more than 20 times higher than the bulk polymer value) while remaining amorphous. This enhancement results from significant molecular chain orientation along the fibre axis that is obtained during electropolymerization using nanoscale templates. Thermal conductivity data suggest that, unlike in drawn crystalline fibres, in our fibres the dominant phonon-scattering process at room temperature is still related to structural disorder. Using vertically aligned arrays of nanofibres, we demonstrate effective heat transfer at critical contacts in electronic devices operating under high-power conditions at 200 °C over numerous cycles. PMID:24681778

  15. Mo' Money, Mo' Problems? High-Achieving Black High School Students' Experiences with Resources, Racial Climate, and Resilience

    ERIC Educational Resources Information Center

    Allen, Walter; Griffin, Kimberly

    2006-01-01

    A multi-site case study analyzed the college preparatory processes of nine African American high achievers attending a well-resourced, suburban high school and eight academically successful African Americans attending a low-resourced urban school. Students at both schools experienced barriers, that is, racial climate and a lack of resources, that…

  16. High IQ Is Sufficient to Explain the High Achievements in Math and Science of the East Asian Peoples

    ERIC Educational Resources Information Center

    Lynn, Richard

    2010-01-01

    It is argued that it is unnecessary to propose that Confucian values explain the high achievements in math and science of the North East Asian peoples, and that these can be satisfactorily and more parsimoniously be explained by their high IQs.

  17. "It's a Way of Life for Us": High Mobility and High Achievement in Department of Defense Schools.

    ERIC Educational Resources Information Center

    Smrekar, Claire E.; Owens, Debra E.

    2003-01-01

    Examines the academic performance of students in U.S. Department of Defense Education Activity (DoDEA) schools, which have high student mobility. Some observers contend that these students' high achievement is a function of their middle class family and community characteristics. Asserts that DoDEA schools simultaneously "do the right things" and…

  18. High Thermal and Electrical Conductivity of Template Fabricated P3HT/MWCNT Composite Nanofibers.

    PubMed

    Smith, Matthew K; Singh, Virendra; Kalaitzidou, Kyriaki; Cola, Baratunde A

    2016-06-15

    Nanoporous alumina membranes are filled with multiwalled carbon nanotubes (MWCNTs) and then poly(3-hexylthiophene-2,5-diyl) (P3HT) melt, resulting in nanofibers with nanoconfinement induced coalignment of both MWCNT and polymer chains. The simple sonication process proposed here can achieve vertically aligned arrays of P3HT/MWCNT composite nanofibers with 3 wt % to 55 wt % MWCNT content, measured using thermogravimetric methods. Electrical and thermal transport in the composite nanofibers improves drastically with increasing carbon nanotube content where nanofiber thermal conductivity peaks at 4.7 ± 1.1 Wm(-1)K(-1) for 24 wt % MWCNT and electrical percolation occurs once 20 wt % MWCNT content is surpassed. This is the first report of the thermal conductivity of template fabricated composite nanofibers and the first proposed processing technique to enable template fabrication of composite nanofibers with high filler content and long aspect ratio fillers, where enhanced properties can also be realized on the macroscale due to vertical alignment of the nanofibers. These materials are interesting for thermal management applications due to their high thermal conductivity and temperature stability. PMID:27200459

  19. A high temperature hybrid photovoltaic-thermal receiver employing spectral beam splitting for linear solar concentrators

    NASA Astrophysics Data System (ADS)

    Mojiri, Ahmad; Stanley, Cameron; Rosengarten, Gary

    2015-09-01

    Hybrid photovoltaic/thermal (PV-T) solar collectors are capable of delivering heat and electricity concurrently. Implementing such receivers in linear concentrators for high temperature applications need special considerations such as thermal decoupling of the photovoltaic (pv) cells from the thermal receiver. Spectral beam splitting of concentrated light provides an option for achieving this purpose. In this paper we introduce a relatively simple hybrid receiver configuration that spectrally splits the light between a high temperature thermal fluid and silicon pv cells using volumetric light filtering by semi-conductor doped glass and propylene glycol. We analysed the optical performance of this device theoretically using ray tracing and experimentally through the construction and testing of a full scale prototype. The receiver was mounted on a commercial parabolic trough concentrator in an outdoor experiment. The prototype receiver delivered heat and electricity at total thermal efficiency of 44% and electrical efficiency of 3.9% measured relative to the total beam energy incident on the primary mirror.

  20. Communication Satisfaction, Organizational Citizenship Behavior and the Relationship to Student Achievement in High Schools

    ERIC Educational Resources Information Center

    Blanchard, Gayle A.

    2012-01-01

    This study used a correlational design that allowed the researcher to examine the relationship among communication satisfaction, organizational citizenship behaviors (OCB) and student achievement. High school teachers were surveyed from a convenience sample of 12 school districts in Arizona. Established instruments were used to survey…

  1. The Relationship between Student Attendance and Academic Achievement in a Selected South Dakota High School

    ERIC Educational Resources Information Center

    Johnke, Jennifer

    2013-01-01

    There is limited research available on the relationship between student attendance and academic achievement in secondary school. This quantitative, non-experimental study, conducted within a South Dakota high school of students in grades 9-12 during the years 2006-2012, examined the relationship between student attendance and academic achievement…

  2. The Transition Experiences of High-Achieving, Low-Income Undergraduates in an Elite College Environment

    ERIC Educational Resources Information Center

    McLoughlin, Paul J., II

    2012-01-01

    This hermeneutic phenomenological study describes the lived experiences of high-achieving, low-income undergraduates and their transition into a college environment historically reserved for wealthy students. The results of this study indicate that these students are flourishing in full need-based financial aid programs as a result of their own…

  3. Central American Refugees and U.S. High Schools. A Psychosocial Study of Motivation and Achievement.

    ERIC Educational Resources Information Center

    Suarez-Orozco, Marcelo M.

    This ethnographic study documents and interprets key school, work, and family life issues in the lives and experiences of a sampling of recent immigrants from the war-torn Central American nations; and suggests a psychocultural theory of achievement motivation. Information was gathered from observation in two urban high schools, interviews with 50…

  4. Growing into Equity: Professional Learning and Personalization in High-Achieving Schools

    ERIC Educational Resources Information Center

    Gleason, Sonia Caus; Gerzon, Nancy

    2013-01-01

    What makes a Title I school high-achieving, and what can we all learn from that experience? Professional learning and leadership that supports personalized instruction makes the difference, as captured in the ground-breaking research of authors Sonia Caus Gleason and Nancy Gerzon. This illuminating book shows how four outstanding schools are…

  5. Excellence in English in Middle and High School: How Teachers' Professional Lives Support Student Achievement.

    ERIC Educational Resources Information Center

    Langer, Judith A.

    The Center on English Learning and Achievement (CELA) has been studying the characteristics of successful English programs in middle and high schools. This report discusses the findings of the first two years of their 5-year Excellence in English study and focuses on the educational practices that support student literacy as well as the…

  6. Performance-Approach Goal Effects on Achievement under Low versus High Challenge Conditions

    ERIC Educational Resources Information Center

    Senko, Corwin; Durik, Amanda M.; Patel, Lily; Lovejoy, Chelsea M.; Valentiner, David

    2013-01-01

    Two studies examined the effects of university students' achievement goals on performance under low versus high challenge conditions. The first was a laboratory experiment in which participants were assigned goals to pursue on a novel mathematics task alleged to be simple or complex to use. The second was a survey study in which students set goals…

  7. High-Stakes Testing and Student Achievement: Updated Analyses with NAEP Data

    ERIC Educational Resources Information Center

    Nichols, Sharon L.; Glass, Gene V.; Berliner, David C.

    2012-01-01

    The present research is a follow-up study of earlier published analyses that looked at the relationship between high-stakes testing pressure and student achievement in 25 states. Using the previously derived Accountability Pressure Index (APR) as a measure of state-level policy pressure for performance on standardized tests, a series of…

  8. The Influence of Social Capital Factors on African-American and Hispanic High School Student Achievement

    ERIC Educational Resources Information Center

    Davis, Jacqueline L.

    2009-01-01

    The underachievement of African American and Hispanic students has been an ongoing problem for schools in the United States. The purpose of this investigation was to add to the existing body of knowledge concerning social capital of African American and Hispanic high school students' academic achievement. Using a nationally representative sample…

  9. Integrating Economic and Social Policy: Good Practices from High-Achieving Countries. Innocenti Working Papers.

    ERIC Educational Resources Information Center

    Mehrotra, Santosh

    This paper examines the successes of 10 "high achievers," countries with social indicators far higher than might be expected, given their national wealth, pulling together the lessons learned for social policy in the developing world. The 10 countries identified are Costa Rica, Cuba, Barbados, Botswana, Zimbabwe, Mauritius, Kerala, Sri Lanka,…

  10. Turning around Reading Achievement: Predictors of High School Students' Academic Resilience.

    ERIC Educational Resources Information Center

    Cappella, Elise; Weinstein, Rhona S.

    2001-01-01

    In a national, longitudinal database, factors were examined that enabled public school students on a path toward failure to significantly improve reading achievement by high school graduation. Being Caucasian and female, having an internal locus of control, and taking an academic curriculum independently predicted academic resilience.…

  11. How Does Bennett Woods Elementary School Produce Such High Reading and Writing Achievement?

    ERIC Educational Resources Information Center

    Pressley, Michael; Mohan, Lindsey; Raphael, Lisa M.; Fingeret, Lauren

    2007-01-01

    The authors developed a grounded theory about how a school serving relatively advantaged children produces high reading and writing achievement compared with schools serving similar populations of students. The school's faculty is reading and writing focused, and students experience many books as they receive explicit, demanding instruction (i.e.,…

  12. What Attracts High-Achieving Socioeconomically Disadvantaged Students to the Physical Sciences and Engineering?

    ERIC Educational Resources Information Center

    Conrad, Sarah; Canetto, Silvia Sara; MacPhee, David; Farro, Samantha

    2009-01-01

    Socioeconomically disadvantaged (SED) students are less likely to major in physical sciences or engineering. To guide recruitment and retention of a diversity of talent, this study examined what attracts high-achieving SED students to these fields. Participants were 50 undergraduates majoring in physical sciences or engineering enrolled in the…

  13. Experiencing More Mathematics Anxiety than Expected? Contrasting Trait and State Anxiety in High Achieving Students

    ERIC Educational Resources Information Center

    Roos, A.-L.; Bieg, M.; Goetz, T.; Frenzel, A. C.; Taxer, J.; Zeidner, M.

    2015-01-01

    This study examined mathematics anxiety among high and low achieving students (N = 237, grades 9 and 10) by contrasting trait (habitual) and state (momentary) assessments of anxiety. Previous studies have found that trait anxiety measures are typically rated higher than state measures. Furthermore, the academic self-concept has been identified to…

  14. An Analysis of the Academic Achievement of Indian High School Students in Federal and Public Schools.

    ERIC Educational Resources Information Center

    Bass, Willard P.

    A longitudinal study was designed to determine whether there were significant differences in academic achievement between senior high American Indian students in Federal on-reservation, Federal off-reservation, public on-reservation, and public off-reservation schools. The purpose of the study was to gather a variety of data on psychological and…

  15. Brain Structure and Resting-State Functional Connectivity in University Professors with High Academic Achievement

    ERIC Educational Resources Information Center

    Li, Weiwei; Yang, Wenjing; Li, Wenfu; Li, Yadan; Wei, Dongtao; Li, Huimin; Qiu, Jiang; Zhang, Qinglin

    2015-01-01

    Creative persons play an important role in technical innovation and social progress. There is little research on the neural correlates with researchers with high academic achievement. We used a combined structural (regional gray matter volume, rGMV) and functional (resting-state functional connectivity analysis, rsFC) approach to examine the…

  16. Effectiveness of Refutational Teaching for High- and Low-Achieving Students

    ERIC Educational Resources Information Center

    Kowalski, Patricia; Taylor, Annette Kujawski

    2011-01-01

    We assessed the effectiveness of refutational readings and lecture on decreasing psychological misconceptions for students of high versus low levels of achievement. During the course of a semester we addressed introductory psychology students' misconceptions with refutational readings, refutational lecture, or not at all. From pre- and post-test…

  17. Faculty Perceptions of High-Achieving Male Collegians: A Critical Race Theory Analysis

    ERIC Educational Resources Information Center

    Comeaux, Eddie

    2013-01-01

    Critical race theory was employed as an interpretive framework to explore faculty perceptions of the academic accomplishments of high-achieving Black and White male collegians. Using photo elicitation methodology, faculty participants responded to a randomly assigned photograph of and vignette about either a Black or White male student. While most…

  18. Differential Predictors of Achievement among Kibbutz and Urban High School Students.

    ERIC Educational Resources Information Center

    Tal, Amos

    1982-01-01

    A study examines environmental and personality factors as predictors of academic achievement among kibbutz and urban high school students. Results of a comparison of personality factors indicate that kibbutz students are more restrained, reserved, adaptable, and conforming. The higher scores of city students on intelligence tests may stem from a…

  19. High Achievement on Advanced Placement Exams: The Relationship of School-Level Contextual Factors to Performance

    ERIC Educational Resources Information Center

    Burney, Virginia H.

    2010-01-01

    The purpose of the study was to identify school- and district-level variables that relate to advanced academic achievement, as defined by the ratio of number of scores of 3, 4, or 5 on Advanced Placement exams to school enrollment. The study initially included 46 variables for 339 public high schools in one Midwestern state. Hierarchical linear…

  20. Diversity and Leadership: A Study of High-Achieving Students of Color

    ERIC Educational Resources Information Center

    St. John, Edward P.; Rowley, Larry L.; Hu, Shouping

    2009-01-01

    Leadership development has long been considered an important outcome of higher education, but the patterns of leadership development among students of color have not been widely studied. This article develops a theory of leadership as an outcome of engaged learning. Findings from this study of high-achieving, low-income students of color include:…

  1. Ugandan Immigrant Students' Perceptions of Barriers to Academic Achievement in American High Schools

    ERIC Educational Resources Information Center

    Ssekannyo, Denis

    2010-01-01

    In a world that is now a global village, enterprising individuals, especially from Third World countries, who make it to greener pastures do not leave their children behind. But with a long list of barriers to academic achievement associated with immigrant and minority students in American high schools, an understanding of the experiences and…

  2. Academic Optimism of High School Teachers: Its Relationship to Organizational Citizenship Behaviors and Student Achievement

    ERIC Educational Resources Information Center

    Wagner, Charles A.; DiPaola, Michael F.

    2011-01-01

    The purpose of this study is to build on an emergent research base for academic optimism by testing the construct and its relationship to student achievement and organizational citizenship behaviors in schools in a sample of public high schools. All participants in this study were full-time teachers, guidance counselors, and other full-time…

  3. Disabled and Successful: Education in the Life Stories of Disabled High Achievers

    ERIC Educational Resources Information Center

    Shah, Sonali; Travers, Cheryl; Arnold, John

    2004-01-01

    There has been much debate concerning the pros and cons of special and mainstream education for young people with a disability. This paper adds data to this debate by reporting the educational experiences of 20 high-achievers with congenital disabilities who live in the United Kingdom and were born between 1950 and 1970. It presents personal…

  4. Balancing Dreams and Realities: The College Choice Process for High-Achieving Latinas

    ERIC Educational Resources Information Center

    Hernández, Ebelia

    2015-01-01

    This study's narratives of 17 high-achieving Latinas revealed how their college choice was a constant balancing of individual and family expectations, being "close, but far enough away," and "getting your money's worth." With the use of critical race theory, further analysis revealed the influence of "familismo" on…

  5. High School Success: An Effective Intervention for Achievement and Dropout Prevention

    ERIC Educational Resources Information Center

    Lowder, Christopher Michael

    2012-01-01

    The purpose of this mixed-design study was to use quantitative and qualitative research to explore the effects of High School Success (a course for at-risk ninth graders) and its effectiveness on student achievement, attendance, and dropout prevention. The research questions address whether there is a significant difference between at-risk ninth…

  6. School Factors Related to Reading Achievement in Rural Schools with and without High Poverty

    ERIC Educational Resources Information Center

    Miller, Seth W.

    2013-01-01

    This quantitative study identified how rural schools differ on five school-level factors related to student achievement according to their performance on Grade 3 reading. Through use of a MANOVA test, it was shown that principals of high-poverty rural schools that made AYP in Grade 3 reading reported significantly higher levels of guaranteed and…

  7. The College-Choice Process of High Achieving Freshmen: A Comparative Case Study

    ERIC Educational Resources Information Center

    Dale, Amanda

    2010-01-01

    The purpose of this study was to examine the college-choice process of high achieving students. Employing current literature and previous research, it combined current models of college choice and the influential factors identified throughout the literature while utilizing the concept of bounded rationality to create a conceptual framework to…

  8. The Relationship between Illinois School District Superintendent Longevity and High School Student Achievement

    ERIC Educational Resources Information Center

    Libka, Robert J.

    2012-01-01

    Frequent changes in school district superintendents may be having a detrimental impact on student achievement. Rapid changes in leadership today parallel the present (NCLB) era of high stakes state assessments. The goal of the study was to provide correlation research that would have a positive effect on school district management, superintendent…

  9. Universal Factors of Student Achievement in High-Performing Eastern and Western Countries

    ERIC Educational Resources Information Center

    Lee, Jihyun

    2014-01-01

    This study investigates whether a common set of student attitudes and behavioral tendencies can account for academic achievement across different, especially high-performing, countries via analysis of the PISA 2009 international data set. The 13 countries examined are 5 of the top-performing Eastern countries/systems, namely Shanghai China, South…

  10. Student Satisfaction and Achievement Related to Organizational Structure: A Study on Semestering in Junior High.

    ERIC Educational Resources Information Center

    Sharman, Rex G.

    1989-01-01

    Examines effects of academic year division on junior high school student satisfaction. Reports no relationship between semester organization and student satisfaction or achievement, although students report dissatisfaction with the length of certain classes. Advanced English students were more satisfied with semester courses than general English…

  11. One-to-One Computing and Student Achievement in Ohio High Schools

    ERIC Educational Resources Information Center

    Williams, Nancy L.; Larwin, Karen H.

    2016-01-01

    This study explores the impact of one-to-one computing on student achievement in Ohio high schools as measured by performance on the Ohio Graduation Test (OGT). The sample included 24 treatment schools that were individually paired with a similar control school. An interrupted time series methodology was deployed to examine OGT data over a period…

  12. Measuring the Outliers: An Introduction to Out-of-Level Testing with High-Achieving Students

    ERIC Educational Resources Information Center

    Rambo-Hernandez, Karen E.; Warne, Russell T.

    2015-01-01

    Out-of-level testing is an underused strategy for addressing the needs of students who score in the extremes, and when used wisely, it could provide educators with a much more accurate picture of what students know. Out-of-level testing has been shown to be an effective assessment strategy with high-achieving students; however, out-of-level…

  13. Emotional Intelligence and Academic Achievement of High School Students in Kanyakumari District

    ERIC Educational Resources Information Center

    Lawrence, A. S. Arul; Deepa, T.

    2013-01-01

    The objective of the study is to find the significant relationship between emotional intelligence and academic achievement of high school students with reference to the background variables. Survey method was employed. Two tools are used in this study namely self-made Trait Emotional Intelligence Questionnaire Short Form (TEIQue SF) and the…

  14. Actively Closing the Gap? Social Class, Organized Activities, and Academic Achievement in High School

    ERIC Educational Resources Information Center

    Morris, David S.

    2015-01-01

    Participation in Organized Activities (OA) is associated with positive behavioral and developmental outcomes in children. However, less is known about how particular aspects of participation affect the academic achievement of high school students from different social class positions. Using the Education Longitudinal Study of 2002, this study…

  15. Effect of Textbook Readability on Student Achievement in High School Chemistry.

    ERIC Educational Resources Information Center

    Rapp, D. Neil

    2001-01-01

    Notes the readability level of many high school chemistry textbooks is far above students' reading levels. Conducts two separate studies, making every effort to keep the two classes as similar as possible in all aspects except text. Finds strong evidence that changing the chemistry textbook resulted in an increase in student achievement. Suggests…

  16. The Federal Transformation Intervention Model in Persistently Lowest Achieving High Schools: A Mixed-Methods Study

    ERIC Educational Resources Information Center

    Le Patner, Michelle B.

    2012-01-01

    This study examined the American Recovery and Reinvestment Act federal mandate of the Transformation Intervention Model (TIM) outlined by the School Improvement Grant, which was designed to turn around persistently lowest achieving schools. The study was conducted in four high schools in a large Southern California urban district that selected the…

  17. Consequences of the Confucian Culture: High Achievement but Negative Psychological Attributes?

    ERIC Educational Resources Information Center

    Ho, Irene T.; Hau, Kit-Tai

    2010-01-01

    In "Unforgiving Confucian culture: A breeding ground for high academic achievement, test anxiety and self-doubt?" Stankov (in press) provides three reasons for caution against over-glorifying the academic excellence of Confucian Asian learners, namely that it may lead to a reluctance to change their rote learning approach which is not conducive to…

  18. The Relationship between Student Achievement and Charter High Schools in Washington, DC

    ERIC Educational Resources Information Center

    Pardo, Alexandra

    2013-01-01

    This study was designed to determine if differences in student achievement existed between traditional public and charter high schools in the District of Columbia. The study examined student outcomes on the standardized state test in reading and math from 2006 to 2010 utilizing descriptive statistics, crosstab analysis, chi-square tests…

  19. Social Media Use, Loneliness, and Academic Achievement: A Correlational Study with Urban High School Students

    ERIC Educational Resources Information Center

    Neto, Roque; Golz, Nancy; Polega, Meaghan

    2015-01-01

    This study explored the association between social media use, loneliness, and academic achievement in high school students and identified the demographic characteristics associated with these three elements. This study also aimed to identify the percentage of variance in loneliness accounted for by social media use and GPA. Participants were 345…

  20. Evaluative and Behavioral Correlates to Intrarehearsal Achievement in High School Bands

    ERIC Educational Resources Information Center

    Montemayor, Mark

    2014-01-01

    The purpose of this study was to investigate relationships of teaching effectiveness, ensemble performance quality, and selected rehearsal procedures to various measures of intrarehearsal achievement (i.e., musical improvement exhibited by an ensemble during the course of a single rehearsal). Twenty-nine high school bands were observed in two…

  1. A Study of the Impact of Block Scheduling on Student Academic Achievement in Public High Schools

    ERIC Educational Resources Information Center

    Norton, Mary Kay

    2010-01-01

    The number of public high schools implementing a semester 4 x 4 block scheduling design within the state of South Carolina has tripled since 2005. However, minimal local research has been conducted regarding the impact of block scheduling on student academic achievement. The purpose of this study was to determine if significant differences exist…

  2. New Counter-School Cultures: Female Students' Drug Use at a High-Achieving Secondary School

    ERIC Educational Resources Information Center

    Fletcher, Adam; Bonell, Chris; Rhodes, Tim

    2009-01-01

    We draw on case-study research at a high-achieving secondary school in London to illustrate how school experiences may influence drug use and reproduce inequalities in reconstructed ways in late modernity. Qualitative data were collected through semi-structured interviews with students and teachers, and observations. We focus in particular on the…

  3. Spatial Experiences of High Academic Achievers: Insights from a Developmental Perspective

    ERIC Educational Resources Information Center

    Weckbacher, Lisa Marie; Okamoto, Yukari

    2012-01-01

    The study explored the relationship between types of spatial experiences and spatial abilities among 13- to 14-year-old high academic achievers. Each participant completed two spatial tasks and a survey assessing favored spatial activities across five categories (computers, toys, sports, music, and art) and three developmental periods (early…

  4. The Impact of Reading Success Academy on High School Reading Achievement

    ERIC Educational Resources Information Center

    Burlison, Kelly; Chave, Josh

    2014-01-01

    The study explores the effectiveness of the Reading Success Academy on the reading achievement of the selected group of ninth-grade students in a comprehensive high school. We examine in what ways the Reading Success Academy may improve the reading proficiency rates and amount of reading growth of ninth-grade students. The results indicate that…

  5. Students' High School Organizational Leadership Opportunities and Their Influences on Academic Achievement and Civic Participation

    ERIC Educational Resources Information Center

    Elemen, Jennifer E.

    2015-01-01

    The purpose of this quantitative study was to analyze high school leadership praxis for its inclusion of students in organizational leadership dialogue and decision-making and the influences of these factors on student achievement and civic participation. Survey questionnaire data were provided by 215 full-time enrolled undergraduate students from…

  6. Antecedent and Concurrent Psychosocial Skills That Support High Levels of Achievement within Talent Domains

    ERIC Educational Resources Information Center

    Olszewski-Kubilius, Paula; Subotnik, Rena F.; Worrell, Frank C.

    2015-01-01

    Motivation and emotional regulation are important for the sustained focused study and practice required for high levels of achievement and creative productivity in adulthood. Using the talent development model proposed by the authors as a framework, the authors discuss several important psychosocial skills based on the psychological research…

  7. Perfectionism in High-Ability Students: Relational Precursors and Influences on Achievement Motivation

    ERIC Educational Resources Information Center

    Speirs Neumeister, Kristie L.; Finch, Holmes

    2006-01-01

    The purpose of the present study was to create and test a model that (a) illustrated variables influencing the development of perfectionism, and (b) demonstrated how different types of perfectionism may influence the achievement goals of high-ability students. Using a multiple groups path analysis, the researchers found that parenting style was…

  8. The Effects of Alcohol Use on Academic Achievement in High School

    ERIC Educational Resources Information Center

    Balsa, Ana I.; Giuliano, Laura M.; French, Michael T.

    2011-01-01

    This paper examines the effects of alcohol use on high school students' quality of learning. We estimate fixed-effects models using data from the National Longitudinal Study of Adolescent Health. Our primary measure of academic achievement is the student's grade point average (GPA) abstracted from official school transcripts. We find that…

  9. Negative Relationship between Achievement in High School and Self-Concept in College.

    ERIC Educational Resources Information Center

    Wolfe, Raymond N.; Grosch, James W.

    Social learning theory implies that there should be a significant positive relationship between academic performance and self-concept and outcomes of recent meta-analyses support this prediction. While path-analytic studies of high school samples in the 1960s and 1970s demonstrated that ability and achievement each made a small positive…

  10. Cognitive Abilities and Motivational Processes in High School Students' Situational Engagement and Achievement in Science.

    ERIC Educational Resources Information Center

    Lau, Shun; Roeser, Robert W.

    2002-01-01

    Building on R. Snow's two pathways to achievement outcomes (1989), examined how cognitive and motivational factors associated with the performance and commitment pathways respectively contributed to prediction of outcomes in science for 491 high school students. Results are consistent with Snow's conjecture that factors related to both pathways…

  11. Obesity, High-Calorie Food Intake, and Academic Achievement Trends among U.S. School Children

    ERIC Educational Resources Information Center

    Li, Jian; O'Connell, Ann A.

    2012-01-01

    The authors investigated children's self-reported high-calorie food intake in Grade 5 and its relationship to trends in obesity status and academic achievement over the first 6 years of school. They used 3-level hierarchical linear models in the large-scale database (the Early Childhood Longitudinal Study--Kindergarten Cohort). Findings indicated…

  12. On the Decline of the Achievement Orientation of High School Females.

    ERIC Educational Resources Information Center

    Schneider, Frank W.; Coutts, Larry M.

    Based on the evidence and theory that sex-role differentiation increases in salience during those later high school years as students prepare for their imminent transition into young adulthood, it was anticipated that there would be a lower orientation toward achievement among grade 12 girls than grade 10 girls, and, possibly, the opposite for…

  13. Organizational Practices of High-Achieving Rural School Districts in California's San Joaquin Valley

    ERIC Educational Resources Information Center

    Doerksen, Amanda López; Wise, Donald

    2016-01-01

    For over 25 years, researchers have identified "best practices" used by high-achieving school districts. However, little research exists regarding rural school systems, making it difficult to determine whether the best practices identified are relevant within this context. This study filled a void in research by focusing on the…

  14. Academic Identity Status, Goal Orientation, and Academic Achievement among High School Students

    ERIC Educational Resources Information Center

    Hejazi, Elaheh; Lavasani, Masoud Gholamali; Amani, Habib; Was, Christopher A.

    2012-01-01

    The aim of the present study was to determine the relationship between academic identity status, goal orientations and academic achievement. 301 first year high school students completed the Academic Identity Measure and Goal Orientation Questionnaire. The average of 10 exam scores in the final semester was used as an index of academic…

  15. The Impact of Inclusion on the Academic Achievement of High School Special Education Students

    ERIC Educational Resources Information Center

    Dawkins, Harold Smith

    2010-01-01

    This dissertation examined the impact of inclusion on the academic achievement outcome of high school special education students as measured by English 1, biology, and algebra 1 as a function of gender, ethnicity, and years of inclusion. The study also examined the generalizations with confidence that could be made about the use of inclusion…

  16. Conflicts and Communication between High-Achieving Chinese American Adolescents and Their Parents

    ERIC Educational Resources Information Center

    Qin, Desiree Baolian; Chang, Tzu-Fen; Han, Eun-Jin; Chee, Grace

    2012-01-01

    Drawing on in-depth interview data collected on 18 high-achieving Chinese American students, the authors examine domains of acculturation-based conflicts, parent and child internal conflicts, and conflict resolution in their families. Their analyses show that well-established negative communication patterns in educational expectations, divergent…

  17. The analysis and rationale behind the upgrading of existing standard definition thermal imagers to high definition

    NASA Astrophysics Data System (ADS)

    Goss, Tristan M.

    2016-05-01

    With 640x512 pixel format IR detector arrays having been on the market for the past decade, Standard Definition (SD) thermal imaging sensors have been developed and deployed across the world. Now with 1280x1024 pixel format IR detector arrays becoming readily available designers of thermal imager systems face new challenges as pixel sizes reduce and the demand and applications for High Definition (HD) thermal imaging sensors increases. In many instances the upgrading of existing under-sampled SD thermal imaging sensors into more optimally sampled or oversampled HD thermal imaging sensors provides a more cost effective and reduced time to market option than to design and develop a completely new sensor. This paper presents the analysis and rationale behind the selection of the best suited HD pixel format MWIR detector for the upgrade of an existing SD thermal imaging sensor to a higher performing HD thermal imaging sensor. Several commercially available and "soon to be" commercially available HD small pixel IR detector options are included as part of the analysis and are considered for this upgrade. The impact the proposed detectors have on the sensor's overall sensitivity, noise and resolution is analyzed, and the improved range performance is predicted. Furthermore with reduced dark currents due to the smaller pixel sizes, the candidate HD MWIR detectors are operated at higher temperatures when compared to their SD predecessors. Therefore, as an additional constraint and as a design goal, the feasibility of achieving upgraded performance without any increase in the size, weight and power consumption of the thermal imager is discussed herein.

  18. Design of High Temperature Ti-Pd-Cr Shape Memory Alloys with Small Thermal Hysteresis

    PubMed Central

    Xue, Deqing; Yuan, Ruihao; Zhou, Yumei; Xue, Dezhen; Lookman, Turab; Zhang, Guojun; Ding, Xiangdong; Sun, Jun

    2016-01-01

    The large thermal hysteresis (ΔT) during the temperature induced martensitic transformation is a major obstacle to the functional stability of shape memory alloys (SMAs), especially for high temperature applications. We propose a design strategy for finding SMAs with small thermal hysteresis. That is, a small ΔT can be achieved in the compositional crossover region between two different martensitic transformations with opposite positive and negative changes in electrical resistance at the transformation temperature. We demonstrate this for a high temperature ternary Ti-Pd-Cr SMA by achieving both a small ΔT and high transformation temperature. We propose two possible underlying physics governing the reduction in ΔT. One is that the interfacial strain is accommodated at the austenite/martensite interface via coexistence of B19 and 9R martensites. The other is that one of transformation eigenvalues equal to 1, i.e., λ2 = 1, indicating a perfect coherent interface between austenite and martensite. Our results are not limited to Ti-Pd-Cr SMAs but potentially provide a strategy for searching for SMAs with small thermal hysteresis. PMID:27328764

  19. Design of High Temperature Ti-Pd-Cr Shape Memory Alloys with Small Thermal Hysteresis.

    PubMed

    Xue, Deqing; Yuan, Ruihao; Zhou, Yumei; Xue, Dezhen; Lookman, Turab; Zhang, Guojun; Ding, Xiangdong; Sun, Jun

    2016-01-01

    The large thermal hysteresis (ΔT) during the temperature induced martensitic transformation is a major obstacle to the functional stability of shape memory alloys (SMAs), especially for high temperature applications. We propose a design strategy for finding SMAs with small thermal hysteresis. That is, a small ΔT can be achieved in the compositional crossover region between two different martensitic transformations with opposite positive and negative changes in electrical resistance at the transformation temperature. We demonstrate this for a high temperature ternary Ti-Pd-Cr SMA by achieving both a small ΔT and high transformation temperature. We propose two possible underlying physics governing the reduction in ΔT. One is that the interfacial strain is accommodated at the austenite/martensite interface via coexistence of B19 and 9R martensites. The other is that one of transformation eigenvalues equal to 1, i.e., λ2 = 1, indicating a perfect coherent interface between austenite and martensite. Our results are not limited to Ti-Pd-Cr SMAs but potentially provide a strategy for searching for SMAs with small thermal hysteresis. PMID:27328764

  20. High-Rise Buildings versus Outdoor Thermal Environment in Chongqing

    PubMed Central

    Lu, Jun; Chen, Jin-hua; Tang, Ying; Feng, Yuan; Wang, Jin-sha

    2007-01-01

    This paper gives a brief description of the over quick urbanization since Chongqing, one of the biggest cities in China, has been a municipality directly under the Central Government in 1997, excessive development and exceeding increase of high-rise buildings because of its special geographical position which finally leads to the worsening of the urban outdoor thermal environment. Then, this paper makes a bright balance to the field measurement and simulated results of the wind speed field, temperature field of one multifunctional high-rise building in Chongqing university located in the city center, and the contrasted results validate the correctness of CFD in the outdoor thermal environmental simulation, expose the disadvantages of high-rise buildings on the aspects of blocking the wind field, decreasing wind speed which results in accumulation of the air-conditioning heat revolving around and periscian region where sunshine can not rip into. Finally, in order to improve the urban outdoor thermal environment near the high-rise buildings especially for the angle of natural ventilation, this paper simulates the wind environment in different architectural compositions and architectural layouts by CFD, and the simulated results show that freestyle and tower buildings which can guarantee the wind speed and take the air-conditioning heat away are much suitable and reasonable for the special Chongqing geography. These conclusions can also be used as a reference in other mountain cities, especially for the one with a great number of populations.

  1. High-field electrical and thermal transport in suspended graphene.

    PubMed

    Dorgan, Vincent E; Behnam, Ashkan; Conley, Hiram J; Bolotin, Kirill I; Pop, Eric

    2013-10-01

    We study the intrinsic transport properties of suspended graphene devices at high fields (≥1 V/μm) and high temperatures (≥1000 K). Across 15 samples, we find peak (average) saturation velocity of 3.6 × 10(7) cm/s (1.7 × 10(7) cm/s) and peak (average) thermal conductivity of 530 W m(-1) K(-1) (310 W m(-1) K(-1)) at 1000 K. The saturation velocity is 2-4 times and the thermal conductivity 10-17 times greater than in silicon at such elevated temperatures. However, the thermal conductivity shows a steeper decrease at high temperature than in graphite, consistent with stronger effects of second-order three-phonon scattering. Our analysis of sample-to-sample variation suggests the behavior of "cleaner" devices most closely approaches the intrinsic high-field properties of graphene. This study reveals key features of charge and heat flow in graphene up to device breakdown at ~2230 K in vacuum, highlighting remaining unknowns under extreme operating conditions. PMID:23387323

  2. High-Field Electrical and Thermal Transport in Suspended Graphene

    NASA Astrophysics Data System (ADS)

    Dorgan, Vincent E.; Behnam, Ashkan; Conley, Hiram J.; Bolotin, Kirill I.; Pop, Eric

    2013-10-01

    We study the intrinsic transport properties of suspended graphene devices at high fields (>1 V/um) and high temperatures (>1000 K). Across 15 samples, we find peak (average) saturation velocity of 3.6x10^7 cm/s (1.7x10^7 cm/s), and peak (average) thermal conductivity of 530 W/m/K (310 W/m/K), at 1000 K. The saturation velocity is 2-4 times and the thermal conductivity 10-17 times greater than in silicon at such elevated temperatures. However, the thermal conductivity shows a steeper decrease at high temperature than in graphite, consistent with stronger effects of second-order three-phonon scattering. Our analysis of sample-to-sample variation suggests the behavior of "cleaner" devices most closely approaches the intrinsic high-field properties of graphene. This study reveals key features of charge and heat flow in graphene up to device breakdown at ~2230 K in vacuum, highlighting remaining unknowns under extreme operating conditions.

  3. Ultra high energy neutrinos: absorption, thermal effects and signatures

    SciTech Connect

    Lunardini, Cecilia; Sabancilar, Eray; Yang, Lili E-mail: Eray.Sabancilar@asu.edu

    2013-08-01

    We study absorption of ultra high energy neutrinos by the cosmic neutrino background, with full inclusion of the effect of the thermal distribution of the background on the resonant annihilation channel. For a hierarchical neutrino mass spectrum (with at least one neutrino with mass below ∼ 10{sup −2} eV), thermal effects are important for ultra high energy neutrino sources at z∼>16. The neutrino transmission probability shows no more than two separate suppression dips since the two lightest mass eigenstates contribute as a single species when thermal effects are included. Results are applied to a number of models of ultra high energy neutrino emission. Suppression effects are strong for sources that extend beyond z ∼ 10, which can be realized for certain top down scenarios, such as superheavy dark matter decays, cosmic strings and cosmic necklaces. For these, a broad suppression valley should affect the neutrino spectrum at least in the energy interval 10{sup 12}−10{sup 13} GeV — which therefore is disfavored for ultra high energy neutrino searches — with only a mild dependence on the neutrino mass spectrum and hierarchy. The observation of absorption effects would indicate a population of sources beyond z ∼ 10, and favor top-down mechanisms; it would also be an interesting probe of the physics of the relic neutrino background in the unexplored redshift interval z ∼ 10–100.

  4. No More 1s: High Expectations Can Lead to High Achievement

    ERIC Educational Resources Information Center

    Cervone, Laureen; DiMartino, Lisa; Kerr, Kris

    2010-01-01

    The school district in Middletown, New York, in the state's Orange County, today serves close to 7,000 students in four elementary schools, two middle schools, and one high school. The district is classified by the state in the highest of three Need-to-Resource-Capacity groups, an urban or suburban school district with high student needs in…

  5. Examining the Success Factors of High-Achieving Puerto Rican Male High-School Students

    ERIC Educational Resources Information Center

    Garrett, Tomas; Antrop-Gonzalez, Rene; Velez, William

    2010-01-01

    This article works to dispel the myth that Latino urban high-school students are not capable of performing at high academic levels. Whereas much educational research emphasizes the academic underachievement of urban Latino students, this article counteracts this research by describing the four success factors that three working-class Puerto Rican…

  6. Cultivating a Growth Mindset in Students at a High-Achieving High School

    ERIC Educational Resources Information Center

    Fegley, Alan D.

    2010-01-01

    The purpose of this EPP is to develop a plan for changing the mindset of a large number of Haddonfield Memorial High School (HMHS) students from a fixed mindset to a growth mindset. HMHS is by most conventional measures a high performing school. Typically 100% of the students graduate with 96% of the students attending two or four year colleges…

  7. Modelling of segmented high-performance thermoelectric generators with effects of thermal radiation, electrical and thermal contact resistances

    NASA Astrophysics Data System (ADS)

    Ouyang, Zhongliang; Li, Dawen

    2016-04-01

    In this study, segmented thermoelectric generators (TEGs) have been simulated with various state-of-the-art TE materials spanning a wide temperature range, from 300 K up to 1000 K. The results reveal that by combining the current best p-type TE materials, BiSbTe, MgAgSb, K-doped PbTeS and SnSe with the strongest n-type TE materials, Cu-Doped BiTeSe, AgPbSbTe and SiGe to build segmented legs, TE modules could achieve efficiencies of up to 17.0% and 20.9% at ΔT = 500 K and ΔT = 700 K, respectively, and a high output power densities of over 2.1 Watt cm‑2 at the temperature difference of 700 K. Moreover, we demonstrate that successful segmentation requires a smooth change of compatibility factor s from one end of the TEG leg to the other, even if s values of two ends differ by more than a factor of 2. The influence of the thermal radiation, electrical and thermal contact effects have also been studied. Although considered potentially detrimental to the TEG performance, these effects, if well-regulated, do not prevent segmentation of the current best TE materials from being a prospective way to construct high performance TEGs with greatly enhanced efficiency and output power density.

  8. Modelling of segmented high-performance thermoelectric generators with effects of thermal radiation, electrical and thermal contact resistances

    PubMed Central

    Ouyang, Zhongliang; Li, Dawen

    2016-01-01

    In this study, segmented thermoelectric generators (TEGs) have been simulated with various state-of-the-art TE materials spanning a wide temperature range, from 300 K up to 1000 K. The results reveal that by combining the current best p-type TE materials, BiSbTe, MgAgSb, K-doped PbTeS and SnSe with the strongest n-type TE materials, Cu-Doped BiTeSe, AgPbSbTe and SiGe to build segmented legs, TE modules could achieve efficiencies of up to 17.0% and 20.9% at ΔT = 500 K and ΔT = 700 K, respectively, and a high output power densities of over 2.1 Watt cm−2 at the temperature difference of 700 K. Moreover, we demonstrate that successful segmentation requires a smooth change of compatibility factor s from one end of the TEG leg to the other, even if s values of two ends differ by more than a factor of 2. The influence of the thermal radiation, electrical and thermal contact effects have also been studied. Although considered potentially detrimental to the TEG performance, these effects, if well-regulated, do not prevent segmentation of the current best TE materials from being a prospective way to construct high performance TEGs with greatly enhanced efficiency and output power density. PMID:27052592

  9. Strength of VGCF/Al Composites for High Thermal Conductivity

    NASA Astrophysics Data System (ADS)

    Fukuchi, Kohei; Sasaki, Katsuhiko; Imanishi, Terumitsu; Katagiri, Kazuaki; Kakitsuji, Atsushi; Shimizu, Akiyuki

    In this paper, the evaluation of the strength of the VGCF/Aluminum composites which have high thermal conductivity is reported. VGCF (Vapor Growth Carbon Fiber) is a kind of the Carbon nanotube (CNT) which has very high thermal conductivity as well as CNT. The composites are made by spark plasma sintering. The stress-strain curves of the composites are obtained by the tensile tests and show that the composites have brittle behavior. The brittleness of the composites increases with increase in the volume fraction of VGCF. A numerical simulation based on the micromechanics is conducted to estimate nonlinear behavior in the elastic deformation and plastic deformation of the stress-strain relations of the composites. The theories of Eshelby, Mori-Tanaka, Weibull, and Ramberg-Osgood are employed for the numerical simulation. The simulations give some information of the microstructural change in the composite related to the volume fraction of VGCF.

  10. Thermal effects in high average power optical parametric amplifiers.

    PubMed

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given. PMID:23455291

  11. The coefficient of thermal expansion of highly enriched 28Si

    NASA Astrophysics Data System (ADS)

    Bartl, Guido; Nicolaus, Arnold; Kessler, Ernest; Schödel, René; Becker, Peter

    2009-10-01

    For the new definition of the SI unit of mass based on a fundamental constant, a redetermination of Avogadro's constant is the goal of an international collaboration of numerous national laboratories and universities. Since a relative uncertainty of about 2 × 10-8 is aimed at, the macroscopic density, the isotopic composition and the volume of the unit cell of a silicon single crystal have to be measured with high precision. One step to improve the precision was the production of a silicon crystal of highly enriched 28Si. This paper addresses the effect of thermal expansion of that material in order to account for a possible discrepancy between the coefficient of thermal expansion (CTE) of natural silicon and that of 28Si. The results of two independent CTE measuring methods are presented and compared in this paper.

  12. High temperature solar thermal technology: The North Africa Market

    SciTech Connect

    Not Available

    1990-12-01

    High temperature solar thermal (HTST) technology offers an attractive option for both industrialized and non-industrialized countries to generate electricity and industrial process steam. The purpose of this report is to assess the potential market for solar thermal applications in the North African countries of Algeria, Egypt, Morocco and Tunisia. North Africa was selected because of its outstanding solar resource base and the variety of applications to be found there. Diminishing oil and gas resources, coupled with expanding energy needs, opens a large potential market for the US industry. The US high temperature solar trough industry has little competition globally and could build a large market in these areas. The US is already familiar with certain solar markets in North Africa due to the supplying of substantial quantities of US-manufactured flat plate collectors to this region.

  13. Thermal lens effects on highly pumped Yb:glass

    NASA Astrophysics Data System (ADS)

    Nishimura, Akihiko; Akaoka, Katsuaki; Ohzu, Akira; Sugiyama, Akira; Usami, Tsutomu; Matoba, Tohru

    2000-04-01

    Thermal lens effects on highly pumped Yb doped phosphate glass was measured by a Shack-Hartmann wavefront sensor for the development of compact chirped pulse amplification systems. High energy pump pulses of 1 - 2 Joules were produced by a flashlamp pumped Ti-sapphire laser. The pumping intensity on the Yb:glass surface exceeded 800 kW/cm2. The pulse energy of 330 mJ from Yb:glass was obtained with 53% slope efficiency with 0.5 Hz reputation. The absorbed pump energy generated the thermal lens effects inside the Yb:glass. The wavefront distortion completely disappeared after 300 ms of pump pulse. Neither heat accumulation nor pumping damage was observed on the Yb:glass.

  14. Comparison of experimental and analytical temperatures achieved by DT-18 and PC-1 shipping containers during hypothetical thermal accident tests

    SciTech Connect

    Anderson, J.C.

    1992-03-01

    Temperatures were monitored at various locations on DT-18 and PC-1 shipping packages during furnace tests at the Y-12 Plant in Oak Ridge, Tennessee. The furnace tests are intended to simulate hypothetical thermal accident conditions specified in Title 10 CFR, Pt. 71.73 (c)(3). Maximum temperatures of the outer containers ranged from 750 to 965{degrees}C while typical maximum temperatures recorded on the inner containers were 60 to 77{degrees}C. One exceptionally high temperature of 196{degrees}C occurred on the PC-1 inner container. Heating 7.1 models of both the DT-18 and PC-1 packages were developed. Models with and without heat generation in the inner containers were developed for each shipping package. The models with heat generation are intended to simulate condensation and convection of hot vapors generated during the heating of the Celotex{trademark} insulating material used in the packages. In general, the analytical models calculate temperatures for the outer containers which agree well with the test data. The HEATING models with and without heat generation bound the inner container test data. These findings are significant in that they lead to the conclusion that heat is transferred to the inner containers through a mechanism other than conduction alone. The high temperature of 196{degrees}C recorded at the PC-1 inner container is within 4{degrees}C of the maximum temperature calculated by the PC-1 HEATING model with heat generation.

  15. Achieving highly dispersed nanofibres at high loading in carbon nanofibre-metal composites

    NASA Astrophysics Data System (ADS)

    Kang, Jianli; Nash, Philip; Li, Jiajun; Shi, Chunsheng; Zhao, Naiqin

    2009-06-01

    In order to tap into the advantages of the properties of carbon nanotubes (CNTs) or carbon nanofibres (CNFs) in composites, the high dispersion of CNTs (or CNFs) and strong interfacial bonding are the key issues which are still challenging. In the current work, a novel approach, consisting of in situ synthesis of CNFs within the Cu powders and mixing Cu ions with the in situ CNF(Ni/Y)-Cu composite powders in a solvent, was developed to highly disperse CNFs in a Cu matrix. The composite, produced by vacuum hot pressing, shows extremely high strength, 3.6 times more than that of the matrix material alone. It is worth mentioning that this method can disperse CNFs at high loading in a metal matrix, inferring good potential for applications, such as electronic packaging materials.

  16. Achievement Motivation of the High School Students: A Case Study among Different Communities of Goalpara District of Assam

    ERIC Educational Resources Information Center

    Sarangi, C.

    2015-01-01

    Achievement motivation is a consistent striving force of an individual to achieve success to a certain standard of excellence in competing situation. In this study an attempt was made to study the effect of achievement motivation on the academic achievement of the high school students of tribal and non tribal communities in relation to their sex…

  17. Are gender differences in high achievement disappearing? A test in one intellectual domain.

    PubMed

    Howard, Robert W

    2005-05-01

    Males traditionally predominate at upper achievement levels. One general view holds that this is due only to various social factors such as the 'glass ceiling' and lack of female role models. Another view holds that it occurs partly because of innate ability differences, with more males being at upper ability levels. In the last few decades, women have become more achievement focused and competitive and have gained many more opportunities to achieve. The present study examined one intellectual domain, international chess, to quantify its gender differences in achievement and to see if these have been diminishing with the societal changes. Chess is a good test domain because it is a meritocracy, it has objective performance measures, and longitudinal data of a whole population are available. Performance ratings overall and in the top 10, 50 and 100 players of each sex show large gender differences and little convergence over the past three decades, although a few females have become high achievers. The distribution of performance ratings on the January 2004 list shows a higher male mean and evidence for more male variation, just as with traits such as height. Career patterns of players first on the list between 1985 and 1989 show that top males and females entered the list at about the same age but females tend to play fewer games and have shorter careers. In this domain at least, the male predominance is large and has remained roughly constant despite societal changes. PMID:15906890

  18. The role of chronotype, gender, test anxiety, and conscientiousness in academic achievement of high school students.

    PubMed

    Rahafar, Arash; Maghsudloo, Mahdis; Farhangnia, Sajedeh; Vollmer, Christian; Randler, Christoph

    2016-01-01

    Previous findings have demonstrated that chronotype (morningness/intermediate/eveningness) is correlated with cognitive functions, that is, people show higher mental performance when they do a test at their preferred time of day. Empirical studies found a relationship between morningness and higher learning achievement at school and university. However, only a few of them controlled for other moderating and mediating variables. In this study, we included chronotype, gender, conscientiousness and test anxiety in a structural equation model (SEM) with grade point average (GPA) as academic achievement outcome. Participants were 158 high school students and results revealed that boys and girls differed in GPA and test anxiety significantly, with girls reporting better grades and higher test anxiety. Moreover, there was a positive correlation between conscientiousness and GPA (r = 0.17) and morningness (r = 0.29), respectively, and a negative correlation between conscientiousness and test anxiety (r = -0.22). The SEM demonstrated that gender was the strongest predictor of academic achievement. Lower test anxiety predicted higher GPA in girls but not in boys. Additionally, chronotype as moderator revealed a significant association between gender and GPA for evening types and intermediate types, while intermediate types showed a significant relationship between test anxiety and GPA. Our results suggest that gender is an essential predictor of academic achievement even stronger than low or absent test anxiety. Future studies are needed to explore how gender and chronotype act together in a longitudinal panel design and how chronotype is mediated by conscientiousness in the prediction of academic achievement. PMID:26651154

  19. Do high-velocity clouds form by thermal instability?

    NASA Astrophysics Data System (ADS)

    Binney, James; Nipoti, Carlo; Fraternali, Filippo

    2009-08-01

    We examine the proposal that the HI `high-velocity' clouds (HVCs) surrounding the Milky Way and other disc galaxies form by condensation of the hot galactic corona via thermal instability. Under the assumption that the galactic corona is well represented by a non-rotating, stratified atmosphere, we find that for this formation mechanism to work the corona must have an almost perfectly flat entropy profile. In all other cases, the growth of thermal perturbations is suppressed by a combination of buoyancy and thermal conduction. Even if the entropy profile were nearly flat, cold clouds with sizes smaller than 10kpc could form in the corona of the Milky Way only at radii larger than 100kpc, in contradiction with the determined distances of the largest HVC complexes. Clouds with sizes of a few kpc can form in the inner halo only in low-mass systems. We conclude that unless even slow rotation qualitatively changes the dynamics of a corona, thermal instability is unlikely to be a viable mechanism for formation of cold clouds around disc galaxies.

  20. Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives

    SciTech Connect

    baney, Ronald; Tulenko, James

    2012-11-20

    The objective of this research is to increase the thermal conductivity of uranium oxide (UO{sub 2}) without significantly impacting its neutronic properties. The concept is to incorporate another high thermal conductivity material, silicon carbide (SiC), in the form of whiskers or from nanoparticles of SiC and a SiC polymeric precursor into UO{sub 2}. This is expected to form a percolation pathway lattice for conductive heat transfer out of the fuel pellet. The thermal conductivity of SiC would control the overall fuel pellet thermal conductivity. The challenge is to show the effectiveness of a low temperature sintering process, because of a UO{sub 2}-SiC reaction at 1,377°C, a temperature far below the normal sintering temperature. Researchers will study three strategies to overcome the processing difficulties associated with pore clogging and the chemical reaction of SiC and UO{sub 2} at temperatures above 1,300°C:

  1. Thermal transport measurements in high-energy-density matter

    NASA Astrophysics Data System (ADS)

    Ping, Yuan

    2015-11-01

    Thermal conductivity is one of the most fundamental physical properties of matter. It determines the heat transport rate and has an enormous impact on a variety of mechanical, electrical, chemical, and nuclear systems. Thermal conduction is important in high energy density (HED) matter such as laboratory fusion plasmas, planetary cores, compact stars, and other celestial objects. Examples are in the ablation and instability growth in inertial confinement fusion (ICF) capsules, in energy loss from ICF hot spot, and in the evolution of Earth's core-mantle boundary. Despite the importance of thermal conductivity in HED systems, experimental measurements under relevant conditions are scarce and challenging. We have developed a method of differential heating for thermal conductivity measurements. In this talk, experimental designs will be described for four different platforms: optical laser heating, proton heating, laser-generated x-ray heating and XFEL heating. Data from various facilities will be presented and comparison with models will be discussed. This work was performed under DOE contract DE-AC52-07NA27344 with support from OFES Early Career program and LLNL LDRD program.

  2. High temperature thermal energy storage in steel and sand

    NASA Technical Reports Server (NTRS)

    Turner, R. H.

    1979-01-01

    The technical and economic potential for high temperature (343 C, 650 F) thermal energy storage in hollow steel ingots, pipes embedded in concrete, and for pipes buried in sand was evaluated. Because it was determined that concrete would separate from pipes due to thermal stresses, concrete was replaced by sand, which is free from thermal stresses. Variations of the steel ingot concept were not cost effective compared to the sand-pipe approach, therefore, the sand-pipe thermal storage unit (TSU) was evaluated in depth to assess the approximate tube spacing requirements consistent with different system performance characteristics and also attendant system costs. For large TSUs which do not require fast response times, the sand-pipe approach offers attractive possibilities. A pipe diameter about 9 cm (3.5 in) and pipe spacing of approximately 25 cm (10 in), with sand filling the interspaces, appears appropriate. Such a TSU system designed for 8 hours charge/discharge cycle has an energy unit storage cost (CE) of $2.63/kWhr-t and a power unit storage cost (Cp) of $42/kW-t (in 1977 dollars).

  3. Organic transistors with high thermal stability for medical applications

    NASA Astrophysics Data System (ADS)

    Kuribara, Kazunori; Wang, He; Uchiyama, Naoya; Fukuda, Kenjiro; Yokota, Tomoyuki; Zschieschang, Ute; Jaye, Cherno; Fischer, Daniel; Klauk, Hagen; Yamamoto, Tatsuya; Takimiya, Kazuo; Ikeda, Masaaki; Kuwabara, Hirokazu; Sekitani, Tsuyoshi; Loo, Yueh-Lin; Someya, Takao

    2012-03-01

    The excellent mechanical flexibility of organic electronic devices is expected to open up a range of new application opportunities in electronics, such as flexible displays, robotic sensors, and biological and medical electronic applications. However, one of the major remaining issues for organic devices is their instability, especially their thermal instability, because low melting temperatures and large thermal expansion coefficients of organic materials cause thermal degradation. Here we demonstrate the fabrication of flexible thin-film transistors with excellent thermal stability and their viability for biomedical sterilization processes. The organic thin-film transistors comprise a high-mobility organic semiconductor, dinaphtho[2,3-b:2‧,3‧-f]thieno[3,2-b]thiophene, and thin gate dielectrics comprising a 2-nm-thick self-assembled monolayer and a 4-nm-thick aluminium oxide layer. The transistors exhibit a mobility of 1.2 cm2 V-1s-1 within a 2 V operation and are stable even after exposure to conditions typically used for medical sterilization.

  4. High fat diet promotes achievement of peak bone mass in young rats

    SciTech Connect

    Malvi, Parmanand; Piprode, Vikrant; Chaube, Balkrishna; Pote, Satish T.; Mittal, Monika; Chattopadhyay, Naibedya; Wani, Mohan R.; Bhat, Manoj Kumar

    2014-12-05

    Highlights: • High fat diet helps in achieving peak bone mass at younger age. • Shifting from high fat to normal diet normalizes obese parameters. • Bone parameters are sustained even after withdrawal of high fat diet. - Abstract: The relationship between obesity and bone is complex. Epidemiological studies demonstrate positive as well as negative correlation between obesity and bone health. In the present study, we investigated the impact of high fat diet-induced obesity on peak bone mass. After 9 months of feeding young rats with high fat diet, we observed obesity phenotype in rats with increased body weight, fat mass, serum triglycerides and cholesterol. There were significant increases in serum total alkaline phosphatase, bone mineral density and bone mineral content. By micro-computed tomography (μ-CT), we observed a trend of better trabecular bones with respect to their microarchitecture and geometry. This indicated that high fat diet helps in achieving peak bone mass and microstructure at younger age. We subsequently shifted rats from high fat diet to normal diet for 6 months and evaluated bone/obesity parameters. It was observed that after shifting rats from high fat diet to normal diet, fat mass, serum triglycerides and cholesterol were significantly decreased. Interestingly, the gain in bone mineral density, bone mineral content and trabecular bone parameters by HFD was retained even after body weight and obesity were normalized. These results suggest that fat rich diet during growth could accelerate achievement of peak bone mass that is sustainable even after withdrawal of high fat diet.

  5. Fabrication of High Temperature Cermet Materials for Nuclear Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Hickman, Robert; Panda, Binayak; Shah, Sandeep

    2005-01-01

    Processing techniques are being developed to fabricate refractory metal and ceramic cermet materials for Nuclear Thermal Propulsion (NTP). Significant advances have been made in the area of high-temperature cermet fuel processing since RoverNERVA. Cermet materials offer several advantages such as retention of fission products and fuels, thermal shock resistance, hydrogen compatibility, high conductivity, and high strength. Recent NASA h d e d research has demonstrated the net shape fabrication of W-Re-HfC and other refractory metal and ceramic components that are similar to UN/W-Re cermet fuels. This effort is focused on basic research and characterization to identify the most promising compositions and processing techniques. A particular emphasis is being placed on low cost processes to fabricate near net shape parts of practical size. Several processing methods including Vacuum Plasma Spray (VPS) and conventional PM processes are being evaluated to fabricate material property samples and components. Surrogate W-Re/ZrN cermet fuel materials are being used to develop processing techniques for both coated and uncoated ceramic particles. After process optimization, depleted uranium-based cermets will be fabricated and tested to evaluate mechanical, thermal, and hot H2 erosion properties. This paper provides details on the current results of the project.

  6. NEUTRONIC REACTOR HAVING LOCALIZED AREAS OF HIGH THERMAL NEUTRON DENSITIES

    DOEpatents

    Newson, H.W.

    1958-06-01

    A nuclear reactor for the irradiation of materials designed to provide a localized area of high thermal neutron flux density in which the materials to be irradiated are inserted is described. The active portion of the reactor is comprised of a cubicle graphite moderator of about 25 feet in length along each axis which has a plurality of cylindrical channels for accommodatirg elongated tubular-shaped fuel elements. The fuel elements have radial fins for spacing the fuel elements from the channel walls, thereby providing spaces through which a coolant may be passed, and also to serve as a heatconductirg means. Ducts for accommnodating the sample material to be irradiated extend through the moderator material perpendicular to and between parallel rows of fuel channels. The improvement is in the provision of additional fuel element channels spaced midway between 2 rows of the regular fuel channels in the localized area surrounding the duct where the high thermal neutron flux density is desired. The fuel elements normally disposed in the channels directly adjacent the duct are placed in the additional channels, and the channels directly adjacent the duct are plugged with moderator material. This design provides localized areas of high thermal neutron flux density without the necessity of providing additional fuel material.

  7. High temperature thermal properties for metals used in LWR vessels

    NASA Astrophysics Data System (ADS)

    Rempe, J. L.; Knudson, D. L.

    2008-01-01

    Because of the impact that melt relocation and vessel failure has on subsequent progression and associated consequences of a light water reactor (LWR) accident, it is important to accurately predict the heatup and relocation of materials within the reactor vessel and heat transfer to and from the reactor vessel. Accurate predictions of such heat transfer phenomena require high temperature thermal properties. However, a review of vessel and structural steel material properties in severe accident analysis codes reveals that the required high temperature material properties are extrapolated with little, if any, data above 700 °C. To reduce uncertainties in predictions relying upon this extrapolated high temperature data, INL obtained data using laser-flash thermal diffusivity techniques for two metals used in LWR vessels: SA 533 Grade B, Class 1 (SA533B1) low alloy steel, which is used to fabricate most US LWR reactor vessels; and Type 304 Stainless Steel SS304, which is used in LWR vessel piping, penetration tubes, and internal structures. This paper summarizes the new data, compares it to existing data in the literature, and provides recommended correlations for thermal properties based on this data.

  8. Thermal shock behaviour of tungsten after high flux H-plasma loading

    NASA Astrophysics Data System (ADS)

    Wirtz, M.; Linke, J.; Pintsuk, G.; De Temmerman, G.; Wright, G. M.

    2013-11-01

    Previous studies have shown that transient thermal shock loads induce crack networks on tungsten samples especially at low base temperatures. To achieve test conditions which are more relevant for the performance of tungsten-armoured plasma facing components in next step thermonuclear fusion devices tungsten tiles were exposed to high flux hydrogen-plasma in the linear plasma generator Pilot-PSI and the high heat flux ion beam test facility MARION. Subsequently, the cyclic transient heat load tests were done in the electron beam facility JUDITH 1. The induced damages after these combined tests were examined by microscopically means, profilometry and metallography. The comparison of the obtained results and damage characteristics with those obtained after thermal shock loading show that the preloading of tungsten targets with high flux hydrogen-plasma has significant influence on the thermal shock behaviour of tungsten in terms of crack distance, width, and depth as well as cracked area. Furthermore the plasma parameters, in particular pulse duration and sample temperature during loading, have strong impact on the damage pattern after thermal shock loading.

  9. High-Powered, Ultrasonically Assisted Thermal Stir Welding

    NASA Technical Reports Server (NTRS)

    Ding, Robert

    2013-01-01

    distance equal to the thickness of the material being welded. The TSW process can be significantly improved by reducing the draw forces. This can be achieved by reducing the friction forces between the weld workpieces and the containment plates. High-power ultrasonic (HPU) vibrations of the containment plates achieve friction reduction in the TSW process. Furthermore, integration of the HPU energy into the TSW stir rod can increase tool life of the stir rod, and can reduce shear forces to which the stir rod is subjected during the welding process. TSW has been used to successfully join 0.500-in (˜13-mm) thick commercially pure (CP) titanium, titanium 6AL- 4V, and titanium 6AL-4V ELI in weld joint lengths up to 9 ft (˜2.75-m) long. In addition, the TSW process was used to fabricate a sub-scale hexagonally shaped gun turret component for the U.S. Navy. The turret is comprised of six 0.5000-in (˜13-mm) thick angled welds. Each angled weld joint was prepared by machining the mating surfaces to 120deg. The angled weld joint was then fixtured using an upper and lower containment plate of the same geometry of the angled weld joint. The weld joint was then stirred by the stir rod as it and the upper and lower containment plates traverse through the angled joint prep.

  10. Metal Hydride Thermal Storage: Reversible Metal Hydride Thermal Storage for High-Temperature Power Generation Systems

    SciTech Connect

    2011-12-05

    HEATS Project: PNNL is developing a thermal energy storage system based on a Reversible Metal Hydride Thermochemical (RMHT) system, which uses metal hydride as a heat storage material. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun is not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. PNNL’s metal hydride material can reversibly store heat as hydrogen cycles in and out of the material. In a RHMT system, metal hydrides remain stable in high temperatures (600- 800°C). A high-temperature tank in PNNL’s storage system releases heat as hydrogen is absorbed, and a low-temperature tank stores the heat until it is needed. The low-cost material and simplicity of PNNL’s thermal energy storage system is expected to keep costs down. The system has the potential to significantly increase energy density.

  11. Asymmetric hydrogenation of ketones: Tactics to achieve high reactivity, enantioselectivity, and wide scope

    PubMed Central

    Ohkuma, Takeshi

    2010-01-01

    Ru complexes with chiral diphosphines and amine-based ligands achieve high catalytic activity and enantioselectivity for the hydrogenation of ketones under neutral to slightly basic conditions. The chiral environment is controllable by changing the combination of these two ligands. A concerted six-membered transition state is proposed to be the origin of the high reactivity. The η6-arene/TsDPEN–Ru and MsDPEN–Cp*Ir catalysts effect the asymmetric reaction under slightly acidic conditions. A variety of chiral secondary alcohols are obtained in high enantiomeric excess. PMID:20228621

  12. The numerical stroop effect in primary school children: a comparison of low, normal, and high achievers.

    PubMed

    Heine, Angela; Tamm, Sascha; De Smedt, Bert; Schneider, Michael; Thaler, Verena; Torbeyns, Joke; Stern, Elsbeth; Verschaffel, Lieven; Jacobs, Arthur

    2010-01-01

    Sixty-six primary school children were selected, of which 21 scored low on a standardized math achievement test, 23 were normal, and 22 high achievers. In a numerical Stroop experiment, children were asked to make numerical and physical size comparisons on digit pairs. The effects of congruity and numerical distance were determined. All children exhibited congruity and distance effects in the numerical comparison. In the physical comparison, children of all performance groups showed Stroop effects when the numerical distance between the digits was large but failed to show them when the distance was small. Numerical distance effects depended on the congruity condition, with a typical effect of distance in the congruent, and a reversed distance effect in the incongruent condition. Our results are hard to reconcile with theories that suggest that deficits in the automaticity of numerical processing can be related to differential math achievement levels. Immaturity in the precision of mappings between numbers and their numerical magnitudes might be better suited to explain the Stroop effects in children. However, as the results for the high achievers demonstrate, in addition to numerical processing capacity per se, domain-general functions might play a crucial role in Stroop performance, too. PMID:20437281

  13. High Energy Density Thermal Batteries: Thermoelectric Reactors for Efficient Automotive Thermal Storage

    SciTech Connect

    2011-11-15

    HEATS Project: Sheetak is developing a new HVAC system to store the energy required for heating and cooling in EVs. This system will replace the traditional refrigerant-based vapor compressors and inefficient heaters used in today’s EVs with efficient, light, and rechargeable hot-and-cold thermal batteries. The high energy density thermal battery—which does not use any hazardous substances—can be recharged by an integrated solid-state thermoelectric energy converter while the vehicle is parked and its electrical battery is being charged. Sheetak’s converters can also run on the electric battery if needed and provide the required cooling and heating to the passengers—eliminating the space constraint and reducing the weight of EVs that use more traditional compressors and heaters.

  14. High-Efficiency Blue Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence from Phenoxaphosphine and Phenoxathiin Derivatives.

    PubMed

    Lee, Sae Youn; Adachi, Chihaya; Yasuda, Takuma

    2016-06-01

    High-efficiency blue thermally activated delayed fluorescence (TADF) molecules, consisting of phenoxaphosphine oxide and phenoxathiin dioxide as acceptor units and 9,9-dimethylacridan as a donor unit, are reported. Maximum external electroluminescence quantum efficiencies of up to 20.5% are achieved in blue organic light-emitting diodes (OLEDs) by employing these materials as TADF emitters. PMID:27059783

  15. A versatile thermally activated delayed fluorescence emitter for both highly efficient doped and non-doped organic light emitting devices.

    PubMed

    Tsai, Wei-Lung; Huang, Ming-Hao; Lee, Wei-Kai; Hsu, Yi-Jiun; Pan, Kuan-Chung; Huang, Yi-Hsiang; Ting, Hao-Chun; Sarma, Monima; Ho, Yu-Yi; Hu, Hung-Chieh; Chen, Chung-Chia; Lee, Meng-Ting; Wong, Ken-Tsung; Wu, Chung-Chih

    2015-09-14

    A thermally activated delayed fluorescent (TADF) emitter (DMAC-TRZ) was reported either as the emitting dopant in a host or as the non-doped (neat) emitting layer to achieve high EL EQEs of up to 26.5% and 20% in OLEDs, respectively. PMID:26226072

  16. Facilitating High Achievement: High School Principals' Reflections on Their Successful Leadership Practices

    ERIC Educational Resources Information Center

    Crum, Karen S.; Sherman, Whitney H.

    2008-01-01

    Purpose: The burden for school improvement in a time of accountability falls squarely on the shoulders of principals as new requirements demand that they act as instructional leaders. The purpose of this study is to discover the common themes of school leadership and instructional practices of high school principals at successful schools in…

  17. High-Achieving African American Male High School Students: A Case Study

    ERIC Educational Resources Information Center

    Hilt, Jason C.

    2011-01-01

    This case study highlighted the fundamental reasons why a small group of African American male high school seniors in the selected school district succeeded academically while their same race peers did not. Through classroom observation, interviews, and focus groups, the researcher uncovered factors related to instructional practices and classroom…

  18. Joule-Thomson cryogenic cooler with extremely high thermal stability

    NASA Technical Reports Server (NTRS)

    Bard, Steven; Wu, J. J.; Trimble, Curt

    1991-01-01

    An 80-K Joule-Thomson (J-T) cooling system designed for the Probe Infrared Laser Spectrometer (PIRLS) proposed for the Huygens Titan Probe of the Cassini Saturn orbiter mission is presented. The cryogenic cooling requirements of the PIRLS instrument are listed, and the cooler system design including details of a J-T cryostat, cold head, and dewar design is described along with the results of a thermal modeling effort and lab cooler performance testing. It is shown that by using active feedback temperature control of the cold head in combination with the self-regulating action of the J-T cryostat, a temperature stability of less than 0.1 mK/min is achieved by the cooler weighting 1.8 kg.

  19. Challenges to achievement of metal sustainability in our high-tech society

    SciTech Connect

    Izatt, Reed M.; Izatt, Steven R.; Bruening, Ronald L.; Izatt, Neil; Moyer, Bruce A

    2014-01-01

    Achievement of sustainability in metal life cycles from mining of virgin ore to consumer and industrial devices to end-of-life products requires greatly increased recycling and improved processing of metals. Electronic and other high-tech products containing precious, toxic, and specialty metals usually have short lifetimes and low recycling rates. Products containing these metals generally are incinerated, discarded as waste in landfills, or dismantled in informal recycling using crude and environmentally irresponsible procedures. Low metal recycling rates coupled with increasing demand for products containing them necessitate increased mining with attendant environmental, health, energy, water, and carbon-footprint consequences. In this tutorial review, challenges to achieving metal sustainability in present high-tech society are presented; health, environmental, and economic incentives for various stakeholders to improve metal sustainability are discussed; a case for technical improvements in separations technology, especially employing molecular recognition, is given; and global consequences of continuing on the present path are examined.

  20. Highly defective oxides as sinter resistant thermal barrier coating

    DOEpatents

    Subramanian, Ramesh

    2005-08-16

    A thermal barrier coating material formed of a highly defective cubic matrix structure having a concentration of a stabilizer sufficiently high that the oxygen vacancies created by the stabilizer interact within the matrix to form multi-vacancies, thereby improving the sintering resistance of the material. The concentration of stabilizer within the cubic matrix structure is greater than that concentration of stabilizer necessary to give the matrix a peak ionic conductivity value. The concentration of stabilizer may be at least 30 wt. %. Embodiments include a cubic matrix of zirconia stabilized by at least 30-50 wt. % yttria, and a cubic matrix of hafnia stabilized by at least 30-50 wt. % gadolinia.

  1. An investigation into high-achiever and low-achiever knowledge organisation and knowledge processing in concept mapping: A case study

    NASA Astrophysics Data System (ADS)

    Siew Lian, Mary Wong

    1998-09-01

    This study used concept map content analysis and interviews to gain insights into the knowledge organisation and knowledge processing of pre-service teachers. Forty-eight preservice teachers of elementary science from a teachers’ training college in Sarawak, Malaysia, participated in this study. Correlations between achievement and five concept map characteristics showed that there were significant positive correlations ( p<.01) between achievement and: the number of appropriate links; the average number of appropriate concepts per cluster; and, the hierarchy score of subjects’ concept maps, and significant negative correlations ( p<.01) between achievement and: the number of inappropriate links; and, the average number of inappropriate concepts per cluster. Interviews with high-achievers and lowachievers revealed that there were differences in the way they processed knowledge during concept mapping. The high-achievers were more thorough than were the low-achievers in cognitive processing of knowledge, taking time to make sense of concepts, sort and group concepts, form relevant links between concepts, and organise concepts hierarchically. Active cognitive processing of knowledge seems to be related to more complex, well-integrated cognitive structures for the material learned.

  2. Effective Thermal Conductivity of High Porosity Open Cell Nickel Foam

    NASA Technical Reports Server (NTRS)

    Sullins, Alan D.; Daryabeigi, Kamran

    2001-01-01

    The effective thermal conductivity of high-porosity open cell nickel foam samples was measured over a wide range of temperatures and pressures using a standard steady-state technique. The samples, measuring 23.8 mm, 18.7 mm, and 13.6 mm in thickness, were constructed with layers of 1.7 mm thick foam with a porosity of 0.968. Tests were conducted with the specimens subjected to temperature differences of 100 to 1000 K across the thickness and at environmental pressures of 10(exp -4) to 750 mm Hg. All test were conducted in a gaseous nitrogen environment. A one-dimensional finite volume numerical model was developed to model combined radiation/conduction heat transfer in the foam. The radiation heat transfer was modeled using the two-flux approximation. Solid and gas conduction were modeled using standard techniques for high porosity media. A parameter estimation technique was used in conjunction with the measured and predicted thermal conductivities at pressures of 10(exp -4) and 750 mm Hg to determine the extinction coefficient, albedo of scattering, and weighting factors for modeling the conduction thermal conductivity. The measured and predicted conductivities over the intermediate pressure values differed by 13%.

  3. The high heritability of educational achievement reflects many genetically influenced traits, not just intelligence.

    PubMed

    Krapohl, Eva; Rimfeld, Kaili; Shakeshaft, Nicholas G; Trzaskowski, Maciej; McMillan, Andrew; Pingault, Jean-Baptiste; Asbury, Kathryn; Harlaar, Nicole; Kovas, Yulia; Dale, Philip S; Plomin, Robert

    2014-10-21

    Because educational achievement at the end of compulsory schooling represents a major tipping point in life, understanding its causes and correlates is important for individual children, their families, and society. Here we identify the general ingredients of educational achievement using a multivariate design that goes beyond intelligence to consider a wide range of predictors, such as self-efficacy, personality, and behavior problems, to assess their independent and joint contributions to educational achievement. We use a genetically sensitive design to address the question of why educational achievement is so highly heritable. We focus on the results of a United Kingdom-wide examination, the General Certificate of Secondary Education (GCSE), which is administered at the end of compulsory education at age 16. GCSE scores were obtained for 13,306 twins at age 16, whom we also assessed contemporaneously on 83 scales that were condensed to nine broad psychological domains, including intelligence, self-efficacy, personality, well-being, and behavior problems. The mean of GCSE core subjects (English, mathematics, science) is more heritable (62%) than the nine predictor domains (35-58%). Each of the domains correlates significantly with GCSE results, and these correlations are largely mediated genetically. The main finding is that, although intelligence accounts for more of the heritability of GCSE than any other single domain, the other domains collectively account for about as much GCSE heritability as intelligence. Together with intelligence, these domains account for 75% of the heritability of GCSE. We conclude that the high heritability of educational achievement reflects many genetically influenced traits, not just intelligence. PMID:25288728

  4. The high heritability of educational achievement reflects many genetically influenced traits, not just intelligence

    PubMed Central

    Krapohl, Eva; Rimfeld, Kaili; Shakeshaft, Nicholas G.; Trzaskowski, Maciej; McMillan, Andrew; Pingault, Jean-Baptiste; Asbury, Kathryn; Harlaar, Nicole; Kovas, Yulia; Dale, Philip S.; Plomin, Robert

    2014-01-01

    Because educational achievement at the end of compulsory schooling represents a major tipping point in life, understanding its causes and correlates is important for individual children, their families, and society. Here we identify the general ingredients of educational achievement using a multivariate design that goes beyond intelligence to consider a wide range of predictors, such as self-efficacy, personality, and behavior problems, to assess their independent and joint contributions to educational achievement. We use a genetically sensitive design to address the question of why educational achievement is so highly heritable. We focus on the results of a United Kingdom-wide examination, the General Certificate of Secondary Education (GCSE), which is administered at the end of compulsory education at age 16. GCSE scores were obtained for 13,306 twins at age 16, whom we also assessed contemporaneously on 83 scales that were condensed to nine broad psychological domains, including intelligence, self-efficacy, personality, well-being, and behavior problems. The mean of GCSE core subjects (English, mathematics, science) is more heritable (62%) than the nine predictor domains (35–58%). Each of the domains correlates significantly with GCSE results, and these correlations are largely mediated genetically. The main finding is that, although intelligence accounts for more of the heritability of GCSE than any other single domain, the other domains collectively account for about as much GCSE heritability as intelligence. Together with intelligence, these domains account for 75% of the heritability of GCSE. We conclude that the high heritability of educational achievement reflects many genetically influenced traits, not just intelligence. PMID:25288728

  5. High-fidelity simulation: Assessment of student nurses' team achievements of clinical judgment.

    PubMed

    Hallin, Karin; Bäckström, Britt; Häggström, Marie; Kristiansen, Lisbeth

    2016-07-01

    Nursing educators have the challenge of preparing nursing students to handle complex patient care situations in real life, but much remains unknown about the ability to make clinical judgments. In this study, high-fidelity simulation (HFS) was used at a Swedish university to find answers about pre-licensure nursing students' success in clinical judgment in terms of team ability and relationships with theoretical achievements, and personal and scenario circumstances. The matrix Lasater Clinical Judgment Rubric (LCJR) was used to analyze and score the students' ability in teams to notice, interpret and respond to complex care situations. Overall, the results showed the student teams in their first meeting with HFS in a complex care situation achieved low clinical judgment points; most teams were in the stages of Beginning and Developing. For attaining high team achievements the majority of the students in the team should theoretically be "high performance". Being observers and having HFS experience before nursing education was significant too. However, age, health care experience, and assistant nurse degrees were of secondary importance. Further research at universities regionally, nationally, and internationally is needed. PMID:27428686

  6. High-precision thermal and electrical characterization of thermoelectric modules

    SciTech Connect

    Kolodner, Paul

    2014-05-15

    This paper describes an apparatus for performing high-precision electrical and thermal characterization of thermoelectric modules (TEMs). The apparatus is calibrated for operation between 20 °C and 80 °C and is normally used for measurements of heat currents in the range 0–10 W. Precision thermometry based on miniature thermistor probes enables an absolute temperature accuracy of better than 0.010 °C. The use of vacuum isolation, thermal guarding, and radiation shielding, augmented by a careful accounting of stray heat leaks and uncertainties, allows the heat current through the TEM under test to be determined with a precision of a few mW. The fractional precision of all measured parameters is approximately 0.1%.

  7. Albion: cost-effective 3rd generation high-performance thermal imaging in the UK

    NASA Astrophysics Data System (ADS)

    McEwen, R. K.; Lupton, M.; Lawrence, M.; Knowles, P.; Wilson, M.; Dennis, P. N. J.; Gordon, N. T.; Lees, D. J.; Parsons, J. F.

    2006-09-01

    The first generation of high performance thermal imaging sensors in the UK was based on two axis opto-mechanical scanning systems and small (4-16 element) arrays of the SPRITE detector, developed during the 1970s. Almost two decades later, a 2nd Generation system, STAIRS C was introduced, based on single axis scanning and a long linear array of approximately 3000 elements. This paper addresses the development of the UK's 3rd Generation High Performance Thermal Imaging sensor systems, under a programme known as "Albion". Three new high performance detectors, manufactured in cadmium mercury telluride, operating in both MWIR and LWIR, providing high resolution and sensitivities without need for opto-mechanical scanning systems will be described. The CMT material is grown by MOVPE on low cost substrates and bump bonded to the silicon read out circuit (ROIC). All three detectors are designed to fit with existing standard Integrated Detector Cooling Assemblies (IDCAs). The two largest detectors will be integrated with field demonstrator cameras providing MWIR and LWIR solutions that can rapidly be tailored to specific military requirements. The remaining detector will be a LWIR device with a smart ROIC, facilitating integration times much longer than can typically be achieved with focal plane arrays and consequently yield very high thermal sensitivity. This device will be demonstrated in a lab based camera system.

  8. Ultralow thermal conductivity and high thermoelectric figure of merit in SnSe crystals

    NASA Astrophysics Data System (ADS)

    Zhao, Li-Dong; Lo, Shih-Han; Zhang, Yongsheng; Sun, Hui; Tan, Gangjian; Uher, Ctirad; Wolverton, C.; Dravid, Vinayak P.; Kanatzidis, Mercouri G.

    2014-04-01

    The thermoelectric effect enables direct and reversible conversion between thermal and electrical energy, and provides a viable route for power generation from waste heat. The efficiency of thermoelectric materials is dictated by the dimensionless figure of merit, ZT (where Z is the figure of merit and T is absolute temperature), which governs the Carnot efficiency for heat conversion. Enhancements above the generally high threshold value of 2.5 have important implications for commercial deployment, especially for compounds free of Pb and Te. Here we report an unprecedented ZT of 2.6 +/- 0.3 at 923 K, realized in SnSe single crystals measured along the b axis of the room-temperature orthorhombic unit cell. This material also shows a high ZT of 2.3 +/- 0.3 along the c axis but a significantly reduced ZT of 0.8 +/- 0.2 along the a axis. We attribute the remarkably high ZT along the b axis to the intrinsically ultralow lattice thermal conductivity in SnSe. The layered structure of SnSe derives from a distorted rock-salt structure, and features anomalously high Grüneisen parameters, which reflect the anharmonic and anisotropic bonding. We attribute the exceptionally low lattice thermal conductivity (0.23 +/- 0.03 W m-1 K-1 at 973 K) in SnSe to the anharmonicity. These findings highlight alternative strategies to nanostructuring for achieving high thermoelectric performance.

  9. Thermal Hydraulics of the Very High Temperature Gas Cooled Reactor

    SciTech Connect

    Chang Oh; Eung Kim; Richard Schultz; Mike Patterson; Davie Petti

    2009-10-01

    The U.S Department of Energy (DOE) is conducting research on the Very High Temperature Reactor (VHTR) design concept for the Next Generation Nuclear Plant (NGNP) Project. The reactor design will be a graphite moderated, thermal neutron spectrum reactor that will produce electricity and hydrogen in a highly efficient manner. The NGNP reactor core will be either a prismatic graphite block type core or a pebble bed core. The NGNP will use very high-burnup, low-enriched uranium, TRISO-coated fuel, and have a projected plant design service life of 60 years. The VHTR concept is considered to be the nearest-term reactor design that has the capability to efficiently produce hydrogen. The plant size, reactor thermal power, and core configuration will ensure passive decay heat removal without fuel damage or radioactive material releases during reactor core-accidents. The objectives of the NGNP Project are to: Demonstrate a full-scale prototype VHTR that is commercially licensed by the U.S. Nuclear Regulatory Commission, and Demonstrate safe and economical nuclear-assisted production of hydrogen and electricity. The DOE laboratories, led by the INL, perform research and development (R&D) that will be critical to the success of the NGNP, primarily in the areas of: • High temperature gas reactor fuels behavior • High temperature materials qualification • Design methods development and validation • Hydrogen production technologies • Energy conversion. This paper presents current R&D work that addresses fundamental thermal hydraulics issues that are relevant to a variety of possible NGNP designs.

  10. Thermal Protective Coating for High Temperature Polymer Composites

    NASA Technical Reports Server (NTRS)

    Barron, Andrew R.

    1999-01-01

    The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

  11. Extremely High Thermal Conductivity of Aligned Carbon Nanotube-Polyethylene Composites

    PubMed Central

    Liao, Quanwen; Liu, Zhichun; Liu, Wei; Deng, Chengcheng; Yang, Nuo

    2015-01-01

    The ultra-low thermal conductivity of bulk polymers may be enhanced by combining them with high thermal conductivity materials such as carbon nanotubes. Different from random doping, we find that the aligned carbon nanotube-polyethylene composites has a high thermal conductivity by non-equilibrium molecular dynamics simulations. The analyses indicate that the aligned composite not only take advantage of the high thermal conduction of carbon nanotubes, but enhance thermal conduction of polyethylene chains. PMID:26552843

  12. Extremely High Thermal Conductivity of Aligned Carbon Nanotube-Polyethylene Composites

    NASA Astrophysics Data System (ADS)

    Liao, Quanwen; Liu, Zhichun; Liu, Wei; Deng, Chengcheng; Yang, Nuo

    2015-11-01

    The ultra-low thermal conductivity of bulk polymers may be enhanced by combining them with high thermal conductivity materials such as carbon nanotubes. Different from random doping, we find that the aligned carbon nanotube-polyethylene composites has a high thermal conductivity by non-equilibrium molecular dynamics simulations. The analyses indicate that the aligned composite not only take advantage of the high thermal conduction of carbon nanotubes, but enhance thermal conduction of polyethylene chains.

  13. High-strength, thermally-stable nanostructured materials

    NASA Astrophysics Data System (ADS)

    Shankar, Ravi

    The properties of two technologically important precipitation-treatable alloys - Al 6061 and Inconel 718, that are deformed to large plastic strains at room temperature by machining, are presented. The strong effect of prior density of precipitates on the consequent microstructure refinement during chip formation was determined by deforming Al 6061 of different tempers to varying levels of strain, by varying the tool rake angle. Chips cut from peak-aged 6061, consisting of a fine dispersion of precipitates, produced the finest microstructure and are composed of sub-100 nm grains. On the other hand, coarser precipitate distributions in over-aged 6061 and an absence of precipitates in solution-treated 6061 resulted in much coarser microstructures. Thermal stability of such nanostructured chips with different levels of strain and precipitate distributions is analyzed by studying evolution of Vickers micro-hardness and microstructure after different heat treatments. Chips produced from the peak-aged temper and over-aged temper soften following heat treatment while those from the solution-treated state first, gain strength before softening. The results are rationalized based on prior studies of the characteristics and kinetics of precipitation and coarsening in Al-Mg-Si systems. It is then demonstrated that precipitate-stabilized nanostructured materials synthesized from a prototypical alloy system - Inconel 718, are extremely stable even after prolonged heat treatment for 240 hours at temperatures as high as one-half of the melting point. This extraordinary thermal stability is traced to the retention of a fine dispersion of precipitates in a nanostructured matrix even after extended heat treatment. It is anticipated that general design principles garnered from understanding of the causal phenomena determining strengthening and thermal stability, can lead to the development of alloy systems for the manufacture of high-strength, thermally-stable nanostructured materials.

  14. Bioinspired modification of h-BN for high thermal conductive composite films with aligned structure.

    PubMed

    Shen, Heng; Guo, Jing; Wang, Hao; Zhao, Ning; Xu, Jian

    2015-03-18

    With the development of microelectronic technology, the demand of insulating electronic encapsulation materials with high thermal conductivity is ever growing and much attractive. Surface modification of chemical inert h-BN is yet a distressing issue which hinders its applications in thermal conductive composites. Here, dopamine chemistry has been used to achieve the facile surface modification of h-BN microplatelets by forming a polydopamine (PDA) shell on its surface. The successful and effective preparation of h-BN@PDA microplatelets has been confirmed by SEM, EDS, TEM, Raman spectroscopy, and TGA investigations. The PDA coating increases the dispersibility of the filler and enhances its interaction with PVA matrix as well. Based on the combination of surface modification and doctor blading, composite films with aligned h-BN@PDA are fabricated. The oriented fillers result in much higher in-plane thermal conductivities than the films with disordered structures produced by casting or using the pristine h-BN. The thermal conductivity is as high as 5.4 W m(-1) K(-1) at 10 vol % h-BN@PDA loading. The procedure is eco-friendly, easy handling, and suitable for the practical application in large scale. PMID:25707681

  15. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    NASA Astrophysics Data System (ADS)

    Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

    2015-04-01

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  16. Dry Blending to Achieve Isotopic Dilution of Highly Enriched Uranium Oxide Materials

    SciTech Connect

    Henry, Roger Neil; Chipman, Nathan Alan; Rajamani, R. K.

    2001-04-01

    The end of the cold war produced large amounts of excess fissile materials in the United States and Russia. The Department of Energy has initiated numerous activities to focus on identifying material management strategies for disposition of these excess materials. To date, many of these planning strategies have included isotopic dilution of highly enriched uranium as a means of reducing the proliferation and safety risks. Isotopic dilution by dry blending highly enriched uranium with natural and/or depleted uranium has been identified as one non-aqueous method to achieve these risk (proliferation and criticality safety) reductions. This paper reviews the technology of dry blending as applied to free flowing oxide materials.

  17. Low Thermal Conductivity, High Durability Thermal Barrier Coatings for IGCC Environments

    SciTech Connect

    Jordan, Eric; Gell, Maurice

    2015-01-15

    Advanced thermal barrier coatings (TBC) are crucial to improved energy efficiency in next generation gas turbine engines. The use of traditional topcoat materials, e.g. yttria-stabilized zirconia (YSZ), is limited at elevated temperatures due to (1) the accelerated undesirable phase transformations and (2) corrosive attacks by calcium-magnesium-aluminum-silicate (CMAS) deposits and moisture. The first goal of this project is to use the Solution Precursor Plasma Spray (SPPS) process to further reduce the thermal conductivity of YSZ TBCs by introducing a unique microstructural feature of layered porosity, called inter-pass boundaries (IPBs). Extensive process optimization accompanied with hundreds of spray trials as well as associated SEM cross-section and laser-flash measurements, yielded a thermal conductivity as low as 0.62 Wm⁻¹K⁻¹ in SPPS YSZ TBCs, approximately 50% reduction of APS TBCs; while other engine critical properties, such as cyclic durability, erosion resistance and sintering resistance, were characterized to be equivalent or better than APS baselines. In addition, modifications were introduced to SPPS TBCs so as to enhance their resistance to CMAS under harsh IGCC environments. Several mitigation approaches were explored, including doping the coatings with Al₂O₃ and TiO₂, applying a CMAS infiltration-inhibiting surface layer, and filling topcoat cracks with blocking substances. The efficacy of all these modifications was assessed with a set of novel CMAS-TBC interaction tests, and the moisture resistance was tested in a custom-built high-temperature moisture rig. In the end, the optimal low thermal conductivity TBC system was selected based on all evaluation tests and its processing conditions were documented. The optimal coating consisted on a thick inner layer of YSZ coating made by the SPPS process having a thermal conductivity 50% lower than standard YSZ coatings topped with a high temperature tolerant CMAS resistant gadolinium

  18. Preoperative treatment planning with intraoperative optimization can achieve consistent high-quality implants in prostate brachytherapy

    SciTech Connect

    Kudchadker, Rajat J.; Pugh, Thomas J.; Swanson, David A.; Bruno, Teresa L.; Bolukbasi, Yasemin; Frank, Steven J.

    2012-01-01

    Advances in brachytherapy treatment planning systems have allowed the opportunity for brachytherapy to be planned intraoperatively as well as preoperatively. The relative advantages and disadvantages of each approach have been the subject of extensive debate, and some contend that the intraoperative approach is vital to the delivery of optimal therapy. The purpose of this study was to determine whether high-quality permanent prostate implants can be achieved consistently using a preoperative planning approach that allows for, but does not necessitate, intraoperative optimization. To achieve this purpose, we reviewed the records of 100 men with intermediate-risk prostate cancer who had been prospectively treated with brachytherapy monotherapy between 2006 and 2009 at our institution. All patients were treated with iodine-125 stranded seeds; the planned target dose was 145 Gy. Only 8 patients required adjustments to the plan on the basis of intraoperative findings. Consistency and quality were assessed by calculating the correlation coefficient between the planned and implanted amounts of radioactivity and by examining the mean values of the dosimetric parameters obtained on preoperative and 30 days postoperative treatment planning. The amount of radioactivity implanted was essentially identical to that planned (mean planned radioactivity, 41.27 U vs. mean delivered radioactivity, 41.36 U; R{sup 2} = 0.99). The mean planned and day 30 prostate V100 values were 99.9% and 98.6%, respectively. The mean planned and day 30 prostate D90 values were 186.3 and 185.1 Gy, respectively. Consistent, high-quality prostate brachytherapy treatment plans can be achieved using a preoperative planning approach, mostly without the need for intraoperative optimization. Good quality assurance measures during simulation, treatment planning, implantation, and postimplant evaluation are paramount for achieving a high level of quality and consistency.

  19. Equilibrium statistical-thermal models in high-energy physics

    NASA Astrophysics Data System (ADS)

    Tawfik, Abdel Nasser

    2014-05-01

    We review some recent highlights from the applications of statistical-thermal models to different experimental measurements and lattice QCD thermodynamics that have been made during the last decade. We start with a short review of the historical milestones on the path of constructing statistical-thermal models for heavy-ion physics. We discovered that Heinz Koppe formulated in 1948, an almost complete recipe for the statistical-thermal models. In 1950, Enrico Fermi generalized this statistical approach, in which he started with a general cross-section formula and inserted into it, the simplifying assumptions about the matrix element of the interaction process that likely reflects many features of the high-energy reactions dominated by density in the phase space of final states. In 1964, Hagedorn systematically analyzed the high-energy phenomena using all tools of statistical physics and introduced the concept of limiting temperature based on the statistical bootstrap model. It turns to be quite often that many-particle systems can be studied with the help of statistical-thermal methods. The analysis of yield multiplicities in high-energy collisions gives an overwhelming evidence for the chemical equilibrium in the final state. The strange particles might be an exception, as they are suppressed at lower beam energies. However, their relative yields fulfill statistical equilibrium, as well. We review the equilibrium statistical-thermal models for particle production, fluctuations and collective flow in heavy-ion experiments. We also review their reproduction of the lattice QCD thermodynamics at vanishing and finite chemical potential. During the last decade, five conditions have been suggested to describe the universal behavior of the chemical freeze-out parameters. The higher order moments of multiplicity have been discussed. They offer deep insights about particle production and to critical fluctuations. Therefore, we use them to describe the freeze-out parameters

  20. Thermal Control Method for High-Current Wire Bundles by Injecting a Thermally Conductive Filler

    NASA Technical Reports Server (NTRS)

    Rodriguez-Ruiz, Juan; Rowles, Russell; Greer, Greg

    2011-01-01

    A procedure was developed to inject thermal filler material (a paste-like substance) inside the power wire bundle coming from solar arrays. This substance fills in voids between wires, which enhances the heat path and reduces wire temperature. This leads to a reduced amount of heat generated. This technique is especially helpful for current and future generation high-power spacecraft (1 kW or more), because the heat generated by the power wires is significant enough to cause unacceptable overheating to critical components that are in close contact with the bundle.

  1. A Study of Gifted High, Moderate, and Low Achievers in Their Personal Characteristics and Attitudes toward School and Teachers

    ERIC Educational Resources Information Center

    Abu-Hamour, Bashir; Al-Hmouz, Hanan

    2013-01-01

    This study examines the problem of underachievement among gifted high school students. Low achievers were compared to high and moderate achievers on their motivation, self-regulation, and attitudes toward their school and teachers. Participants were all highly able students from grades 10 and 11 in an academically selective gifted high school in…

  2. Progress toward achieving high power and high efficiency semipolar LEDs and their characterization

    NASA Astrophysics Data System (ADS)

    Zhong, Hong

    Performance of current commercially available wurtzite nitride based light-emitting diodes (LEDs), grown along the polar (0001) c-plane orientation, is limited by the presence of polarization-related electric fields inside multi-quantum wells (MQWs). The discontinuities in both spontaneous and piezoelectric polarization at the heterointerfaces result in internal electric fields in the quantum wells. These electric fields cause carrier separation [quantum confined Stark effect (QCSE)] and reduce the radiative recombination rate within the quantum wells. One approach to reduce and possibly eliminate the polarization-related effects is to grow III-nitride devices on crystal planes that are inclined with respect to the c-axis, i.e., on semipolar planes. In this dissertation, metalorganic chemical vapor deposition (MOCVD) has been employed for the homoepitaxial growth of GaN based LEDs on semipolar orientations. As a consequence of growing on high-quality bulk GaN substrates, the LEDs have significantly reduced threading dislocation and stacking fault densities, resulting in remarkable improvements in EQE and output power. High efficiency semipolar (1011) violet-blue and blue LEDs have been demonstrated without any intentional effort to enhance the light extraction from those devices. Optimizations of epitaxial structures have led to increased output power and external quantum efficiency. A silicone encapsulated single quantum well blue LED with peak wavelength of 444 nm with output power of 24.3 mW, external quantum efficiency of 43% and luminous efficacy of 75 lm/W (with phosphorescent coating) at 20 mA has been demonstrated. Polarization fields in strained (1011) and (112¯2) InGaN quantum wells have been experimentally determined through bias-dependent optical studies. Our results show that the polarization field flips its direction in semipolar InGaN quantum wells with large inclination angles (i.e. around 60°). This suggests that there exists a polarization

  3. Strategies to achieve high-solids enzymatic hydrolysis of dilute-acid pretreated corn stover.

    PubMed

    Geng, Wenhui; Jin, Yongcan; Jameel, Hasan; Park, Sunkyu

    2015-01-01

    Three strategies were presented to achieve high solids loading while maximizing carbohydrate conversion, which are fed-batch, splitting/thickening, and clarifier processes. Enzymatic hydrolysis was performed at water insoluble solids (WIS) of 15% using washed dilute-acid pretreated corn stover. The carbohydrate concentration increased from 31.8 to 99.3g/L when the insoluble solids content increased from 5% to 15% WIS, while the final carbohydrate conversion was decreased from 78.4% to 73.2%. For the fed-batch process, a carbohydrate conversion efficiency of 76.8% was achieved when solid was split into 60:20:20 ratio, with all enzymes added first. For the splitting/thickening process, a carbohydrate conversion of 76.5% was realized when the filtrate was recycled to simulate a steady-state process. Lastly, the clarifier process was evaluated and the highest carbohydrate conversion of 81.4% was achieved. All of these results suggests the possibility of enzymatic hydrolysis at high solids to make the overall conversion cost-competitive. PMID:25836373

  4. Achieving all-dielectric metamaterial band-pass frequency selective surface via high-permittivity ceramics

    NASA Astrophysics Data System (ADS)

    Li, Liyang; Wang, Jiafu; Ma, Hua; Wang, Jun; Feng, Mingde; Du, Hongliang; Yan, Mingbao; Zhang, Jieqiu; Qu, Shaobo; Xu, Zhuo

    2016-03-01

    In this paper, we propose the design of all-dielectric metamaterial band-pass frequency selective surfaces (FSSs) using high-permittivity ceramics based on effective medium theory and dielectric resonator theory. The band-pass response can be determined by the permittivity of the dielectric material, the periodicity, and geometrical shape of the dielectric unit cell. As an example, a band-pass FSS composed of H shaped ceramic resonators is demonstrated. Both the simulation and experiment results show that the FSS can achieve a pass band in X-band. Since such FSSs are made of low-loss high-permittivity ceramics, they are of important application values, especially in high-temperature, high-power environments. The design method can be readily extended to the design of FSSs in other frequencies.

  5. The role of shaping in achieving high performance in DIII-D

    SciTech Connect

    Lazarus, E.A.; Hyatt, A.W.; Osborne, T.H.

    1994-10-01

    Experiments to study the effect of plasma shape on performance show that the high performance levels characteristic of VH-mode plasmas are only obtained for high triangularity ({delta}). A characteristic difference in central heating efficiency is observed when high and low {delta} plasmas are compared. The authors find this difference to correlate well with the attainment of Mercier stability. The core plasma for the high {delta} cases achieves Mercier stability when q{sub 0} rises above a critical value which depends on {delta}, providing direct access to the second-stable regime. Other attributes of the VH-mode commence after a delay. The rise in q{sub 0} is attributable to the radial gradients in the neutral beam and bootstrap current sources. Simulation indicates that such plasmas would persist for many seconds if the rise in density could be controlled, maintaining a centrally peaked neutral beam deposition profile.

  6. Using high pressure to study thermal transport and phonon scattering mechanisms

    NASA Astrophysics Data System (ADS)

    Hohensee, Gregory Thomas

    intrinsic phonon-mediated interface conductance between dissimilar materials, I applied DAC-TDTR to measure the thermal conductance of a series of metal-diamond interfaces as a function of pressure up to 50 GPa. The thermal conductance of interfaces between metals and diamond, which has a comparatively high Debye temperature, is often greater than can be accounted for by two phonon-processes, and the nature of heat transport between such dissimilar materials is central to the thermal design of composite materials. The high pressures achievable in a diamond anvil cell can significantly extend the metal phonon density of states to higher frequencies, and can also suppress extrinsic effects by greatly stiffening interface bonding. I measured the interface thermal conductances of Pb, Au0.95Pd0.05, Pt, and Al films deposited on Type 1A natural [100] and Type 2A synthetic [110] diamond anvils, from ambient pressure to 50 GPa. In all cases, the thermal conductances increase weakly or saturate to similar values at high pressure. My results suggest that anharmonic conductance at metal-diamond interfaces is controlled by partial transmission processes, where a diamond phonon that inelastically scatters at the interface absorbs or emits a metal phonon. The thermal conductivity and absolute electrical resistivity of metallic silicon have not been measured previously. I performed regular and beam-offset TDTR to establish the thermal conductivities of Si and Si0.991Ge 0.009 across the semiconductor-metal phase transition and up to 45 GPa. The thermal conductivities of metallic Si and Si(Ge) are comparable to aluminum and indicative of predominantly electronic heat carriers. Metallic Si and Si(Ge) have a transport anisotropy of approximately 1.4, similar to that of beryllium, due to the primitive hexagonal crystal structure. I used the Wiedemann-Franz law to derive the associated electrical resistivity, and found it consistent with the Bloch-Gruneisen model. Not all crystalline point

  7. Albion: the UK 3rd generation high-performance thermal imaging programme

    NASA Astrophysics Data System (ADS)

    McEwen, R. K.; Lupton, M.; Lawrence, M.; Knowles, P.; Wilson, M.; Dennis, P. N. J.; Gordon, N. T.; Lees, D. J.; Parsons, J. F.

    2007-04-01

    The first generation of high performance thermal imaging sensors in the UK was based on two axis opto-mechanical scanning systems and small (4-16 element) arrays of the SPRITE detector, developed during the 1970s. Almost two decades later, a 2nd Generation system, STAIRS C was introduced, based on single axis scanning and a long linear array of approximately 3000 elements. The UK has now begun the industrialisation of 3 rd Generation High Performance Thermal Imaging under a programme known as "Albion". Three new high performance cadmium mercury telluride arrays are being manufactured. The CMT material is grown by MOVPE on low cost substrates and bump bonded to the silicon read out circuit (ROIC). To maintain low production costs, all three detectors are designed to fit with existing standard Integrated Detector Cooling Assemblies (IDCAs). The two largest focal planes are conventional devices operating in the MWIR and LWIR spectral bands. A smaller format LWIR device is also described which has a smart ROIC, enabling much longer stare times than are feasible with conventional pixel circuits, thus achieving very high sensitivity. A new reference surface technology for thermal imaging sensors is described, based on Negative Luminescence (NL), which offers several advantages over conventional peltier references, improving the quality of the Non-Uniformity Correction (NUC) algorithms.

  8. High thermal power density heat transfer apparatus providing electrical isolation at high temperature using heat pipes

    NASA Technical Reports Server (NTRS)

    Morris, J. F. (Inventor)

    1985-01-01

    This invention is directed to transferring heat from an extremely high temperature source to an electrically isolated lower temperature receiver. The invention is particularly concerned with supplying thermal power to a thermionic converter from a nuclear reactor with electric isolation. Heat from a high temperature heat pipe is transferred through a vacuum or a gap filled with electrically nonconducting gas to a cooler heat pipe. If the receiver requires gratr thermal power density, geometries are used with larger heat pipe areas for transmitting and receiving energy than the area for conducting the heat to the thermionic converter. In this way the heat pipe capability for increasing thermal power densities compensates for the comparative low thermal power densities through the electrically nonconducting gap between the two heat pipes.

  9. The effects of modeling instruction on high school physics academic achievement

    NASA Astrophysics Data System (ADS)

    Wright, Tiffanie L.

    The purpose of this study was to explore whether Modeling Instruction, compared to traditional lecturing, is an effective instructional method to promote academic achievement in selected high school physics classes at a rural middle Tennessee high school. This study used an ex post facto , quasi-experimental research methodology. The independent variables in this study were the instructional methods of teaching. The treatment variable was Modeling Instruction and the control variable was traditional lecture instruction. The Treatment Group consisted of participants in Physical World Concepts who received Modeling Instruction. The Control Group consisted of participants in Physical Science who received traditional lecture instruction. The dependent variable was gains scores on the Force Concepts Inventory (FCI). The participants for this study were 133 students each in both the Treatment and Control Groups (n = 266), who attended a public, high school in rural middle Tennessee. The participants were administered the Force Concepts Inventory (FCI) prior to being taught the mechanics of physics. The FCI data were entered into the computer-based Statistical Package for the Social Science (SPSS). Two independent samples t-tests were conducted to answer the research questions. There was a statistically significant difference between the treatment and control groups concerning the instructional method. Modeling Instructional methods were found to be effective in increasing the academic achievement of students in high school physics. There was no statistically significant difference between FCI gains scores for gender. Gender was found to have no effect on the academic achievement of students in high school physics classes. However, even though there was not a statistically significant difference, female students' gains scores were higher than male students' gains scores when Modeling Instructional methods of teaching were used. Based on these findings, it is recommended

  10. Measurement of thermal conductivity of Bi2Te3 nanowire using high-vacuum scanning thermal wave microscopy

    NASA Astrophysics Data System (ADS)

    Park, Kyungbae; Hwang, Gwangseok; Kim, Hayeong; Kim, Jungwon; Kim, Woochul; Kim, Sungjin; Kwon, Ohmyoung

    2016-02-01

    With the increasing application of nanomaterials in the development of high-efficiency thermoelectric energy conversion materials and electronic devices, the measurement of the intrinsic thermal conductivity of nanomaterials in the form of nanowires and nanofilms has become very important. However, the current widely used methods for measuring thermal conductivity have difficulties in eliminating the influence of interfacial thermal resistance (ITR) during the measurement. In this study, by using high-vacuum scanning thermal wave microscopy (HV-STWM), we propose a quantitative method for measuring the thermal conductivity of nanomaterials. By measuring the local phase lag of high-frequency (>10 kHz) thermal waves passing through a nanomaterial in a high-vacuum environment, HV-STWM eliminates the measurement errors due to ITR and the distortion due to heat transfer through air. By using HV-STWM, we measure the thermal conductivity of a Bi2Te3 nanowire. Because HV-STWM is quantitatively accurate and its specimen preparation is easier than in the thermal bridge method, we believe that HV-STWM will be widely used for measuring the thermal properties of various types of nanomaterials.

  11. Moving to higher ground: Closing the high school science achievement gap

    NASA Astrophysics Data System (ADS)

    Mebane, Joyce Graham

    The purpose of this study was to examine the perceptions of West High School constituents (students, parents, teachers, administrators, and guidance counselors) about the readiness and interest of African American students at West High School to take Advanced Placement (AP) and International Baccalaureate (IB) science courses as a strategy for closing the achievement gap. This case study utilized individual interviews and questionnaires for data collection. The participants were selected biology students and their parents, teachers, administrators, and guidance counselors at West High School. The results of the study indicated that just over half the students and teachers, most parents, and all guidance counselors thought African American students were prepared to take AP science courses. Only one of the three administrators thought the students were prepared to take AP science courses. Between one-half and two-thirds of the students, parents, teachers, and administrators thought students were interested in taking an AP science course. Only two of the guidance counselors thought there was interest among the African American students in taking AP science courses. The general consensus among the constituents about the readiness and interest of African American students at West High School to take IB science courses was that it is too early in the process to really make definitive statements. West is a prospective IB school and the program is new and not yet in place. Educators at the West High School community must find reasons to expect each student to succeed. Lower expectations often translate into lower academic demands and less rigor in courses. Lower academic demands and less rigor in courses translate into less than adequate performance by students. When teachers and administrators maintain high expectations, they encourage students to aim high rather than slide by with mediocre effort (Lumsden, 1997). As a result of the study, the following suggestions should

  12. Technical challenges and future direction for high-efficiency metal hydride thermal energy storage systems

    NASA Astrophysics Data System (ADS)

    Ward, Patrick A.; Corgnale, Claudio; Teprovich, Joseph A.; Motyka, Theodore; Hardy, Bruce; Sheppard, Drew; Buckley, Craig; Zidan, Ragaiy

    2016-04-01

    Recently, there has been increasing interest in thermal energy storage (TES) systems for concentrated solar power (CSP) plants, which allow for continuous operation when sunlight is unavailable. Thermochemical energy storage materials have the advantage of much higher energy densities than latent or sensible heat materials. Furthermore, thermochemical energy storage systems based on metal hydrides have been gaining great interest for having the advantage of higher energy densities, better reversibility, and high enthalpies. However, in order to achieve higher efficiencies desired of a thermal storage system by the US Department of Energy, the system is required to operate at temperatures >600 °C. Operation at temperatures >600 °C presents challenges including material selection, hydrogen embrittlement and permeation of containment vessels, appropriate selection of heat transfer fluids, and cost. Herein, the technical difficulties and proposed solutions associated with the use of metal hydrides as TES materials in CSP applications are discussed and evaluated.

  13. Design and global optimization of high-efficiency solar thermal systems with tungsten cermets.

    PubMed

    Chester, David; Bermel, Peter; Joannopoulos, John D; Soljacic, Marin; Celanovic, Ivan

    2011-05-01

    Solar thermal, thermoelectric, and thermophotovoltaic (TPV) systems have high maximum theoretical efficiencies; experimental systems fall short because of losses by selective solar absorbers and TPV selective emitters. To improve these critical components, we study a class of materials known as cermets. While our approach is completely general, the most promising cermet candidate combines nanoparticles of silica and tungsten. We find that 4-layer silica-tungsten cermet selective solar absorbers can achieve thermal transfer efficiencies of 84.3% at 400 K, and 75.59% at 1000 K, exceeding comparable literature values. Three layer silica-tungsten cermets can also be used as selective emitters for InGaAsSb-based thermophotovoltaic systems, with projected overall system energy conversion efficiencies of 10.66% at 1000 K using realistic design parameters. The marginal benefit of adding more than 4 cermet layers is small (less than 0.26%, relative). PMID:21643366

  14. Thermal Stabilization in a High Vacuum Cryogenic Optical System

    NASA Astrophysics Data System (ADS)

    Wallace, Rosa; Cripe, Jonathan; Corbitt, Thomas

    2016-03-01

    The existing technology for gravitational wave detection is limited in part by quantum noise. In our tabletop experiments, we are attempting to lower the noise floor to the quantum limit through the use of a seismically isolated cryogenic high vacuum environment, with the intention of exploring different methods to reduce quantum noise. In the development phase of this environment, we have implemented a customized strategy of ultraviolet irradiation combined with cryogenically cooled radiation shielding to reduce the impact of water vapor and blackbody radiation on the thermal stability of the cryogenic micro-components. Supported by National Science Foundation REU Site #1262890 and CAREER Award #1150531.

  15. Process of making cryogenically cooled high thermal performance crystal optics

    SciTech Connect

    Kuzay, T.M.

    1990-06-29

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N{sub 2} is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  16. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  17. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, Tuncer M.

    1992-01-01

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  18. Fiber Bragg Gratings for High-Temperature Thermal Characterization

    SciTech Connect

    Stinson-Bagby, Kelly L.; Fielder, Robert S.

    2004-07-01

    Fiber Bragg grating (FBG) sensors were used as a characterization tool to study the SAFE-100 thermal simulator at the Nasa Marshal Space Flight Center. The motivation for this work was to support Nasa space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. Distributed high temperature measurements, up to 1150 deg. C, were made with FBG temperature sensors. Additionally, FBG strain measurements were taken at elevated temperatures to provide a strain profile of the core during operation. This paper will discuss the contribution of these measurements to meet the goals of Nasa Marshall Space Flight Center's Propulsion Research Center. (authors)

  19. High sensitivity of positron annihilation to thermal oxidation of polyethylene

    NASA Astrophysics Data System (ADS)

    Ito, Kenji; Kobayashi, Yoshinori; Nanasawa, Atsushi

    2003-01-01

    We demonstrate the high sensitivity of positron annihilation to compositional changes related to the thermal degradation of polyethylene (PE). Positron annihilation γ-ray and lifetime measurements were conducted for PE films with and without antioxidant (1000-ppm Ciba® IRGANOX® 1076), subjected to heat treatment at 100 °C for different periods, to a maximum of 30 days. For the film without antioxidant, the positron Doppler parameter (S) and ortho-positronium formation probability (Io-Ps) appreciably decreased with increased heat treatment times, whereas they barely changed for the film with antioxidant. This, together with the Fourier transform infrared measurements, demonstrated that the variations of S and Io-Ps are caused by the thermal oxidation of PE. The S parameter was found to be sensitive to the early stage of degradation, where the carbonyl concentration is inferred to be lower than 100 ppm. The high sensitivity results from the large positron mobility in PE and from the high positron affinity of oxygen-containing polar groups. This work provides the basis for an application of positron annihilation to sensitive detection of the initial degradation of PE and other nonpolar polymers.

  20. Application of thermal spray coatings using high deposition rate equipment

    SciTech Connect

    Novak, H.L.

    1995-12-01

    Reusable launch vehicles located by the ocean are subject to harsh seacoast environments before launch and immersion after splashdown at sea and towback to the refurbishment facility. High strength aluminum and non-corrosion resistant steel alloys are prone to general corrosion and pitting due to galvanic couples and protective coating damage. Additional protection of structural materials with thermally sprayed pure aluminum coatings was evaluated for plasma, arc spray and high velocity oxy-fuel (HVOF) processes. Comparisons are made for corrosion rates of various coated aluminum alloy and steel substrates when exposed to ASTM B-117 neutral salt fog testing and also to beach exposure tests performed at Kennedy Space Center, Florida. Recent development work involved the use of high deposition rate thermal arc-spray equipment. The use of an inverter power supply reduced powdering and enhanced operator visibility. Deposition rates of 45.36--68.04 kilograms/hour are obtainable using 4.76--6.35 millimeter diameter wire electrodes.

  1. Thermal investigation on high power dfb broad area lasers at 975 nm, with 60% efficiency

    NASA Astrophysics Data System (ADS)

    Mostallino, R.; Garcia, M.; Deshayes, Y.; Larrue, A.; Robert, Y.; Vinet, E.; Bechou, L.; Lecomte, M.; Parillaud, O.; Krakowski, M.

    2016-03-01

    The demand of high power diode lasers in the range of 910-980nm is regularly growing. This kind of device for many applications, such as fiber laser pumping [1], material processing [1], solid-state laser pumping [1], defense and medical/dental. The key role of this device lies in the efficiency (𝜂𝐸) of converting input electrical power into output optical power. The high value of 𝜂𝐸 allows high power level and reduces the need in heat dissipation. The requirement of wavelength stabilization with temperature is more obvious in the case of multimode 975nm diode lasers used for pumping Yb, Er and Yb/Er co-doped solid-state lasers, due to the narrow absorption line close to this wavelength. Such spectral width property (<1 nm), combined with wavelength thermal stabilization (0.07 𝑛𝑚 • °𝐶-1), provided by a uniform distributed feedback grating (DFB) introduced by etching and re-growth process techniques, is achievable in high power diode lasers using optical feedback. This paper reports on the development of the diode laser structure and the process techniques required to write the gratings taking into account of the thermal dissipation and optical performances. Performances are particularly determined in terms of experimental electro-optical characterizations. One of the main objectives is to determine the thermal resistance of the complete assembly to ensure the mastering of the diode laser temperature for operating condition. The classical approach to determine junction temperature is based on the infrared thermal camera, the spectral measurement and the pulse electrical method. In our case, we base our measurement on the spectral measurement but this approach is not well adapted to the high power diodes laser studied. We develop a new measurement based on the pulse electrical method and using the T3STERequipment. This method is well known for electronic devices and LEDs but is weakly developed for the high

  2. A strategy for achieving high reliability for reusable launch vehicles (RLVs)

    NASA Astrophysics Data System (ADS)

    Sholtis, Joseph A.

    2002-01-01

    Expendable launch vehicles (ELVs) have been used since the early 1960s to put numerous payloads, including humans, into space. Yet, in spite of their widespread use since that time, ELV reliability has not improved much. Why has this been the case? And, more importantly, what might be done to substantially improve the reliability of future reusable launch vehicles (RLVs) to levels needed for commercial viability, i.e., approaching that of the U.S. commercial airline industry? This paper attempts to answer these questions-by reviewing the history of launch vehicles, identifying factors important to their reliability and safety, and in doing so, offering a potential strategy for achieving high RLV reliability. The conclusion reached is that there is every reason to believe that high reliability (~0.99999 per mission) is achievable for future RLVs, if key features to enhance their inherent robustness, forgiveness, and recoverability are considered and integrated into RLV design and operation at the outset. It is hoped that this paper will serve as a catalyst for further discussions intended to ensure that high reliability is realized for RLVs. .

  3. Achieving High Performance in AC-Field Driven Organic Light Sources

    PubMed Central

    Xu, Junwei; Carroll, David L.; Smith, Gregory M.; Dun, Chaochao; Cui, Yue

    2016-01-01

    Charge balance in organic light emitting structures is essential to simultaneously achieving high brightness and high efficiency. In DC-driven organic light emitting devices (OLEDs), this is relatively straight forward. However, in the newly emerging, capacitive, field-activated AC-driven organic devices, charge balance can be a challenge. In this work we introduce the concept of gating the compensation charge in AC-driven organic devices and demonstrate that this can result in exceptional increases in device performance. To do this we replace the insulator layer in a typical field-activated organic light emitting device with a nanostructured, wide band gap semiconductor layer. This layer acts as a gate between the emitter layer and the voltage contact. Time resolved device characterization shows that, at high-frequencies (over 40 kHz), the semiconductor layer allows for charge accumulation in the forward bias, light generating part of the AC cycle and charge compensation in the negative, quiescent part of the AC cycle. Such gated AC organic devices can achieve a non-output coupled luminance of 25,900 cd/m2 with power efficiencies that exceed both the insulator-based AC devices and OLEDs using the same emitters. This work clearly demonstrates that by realizing balanced management of charge, AC-driven organic light emitting devices may well be able to rival today’s OLEDs in performance. PMID:27063414

  4. Achieving High Performance in AC-Field Driven Organic Light Sources.

    PubMed

    Xu, Junwei; Carroll, David L; Smith, Gregory M; Dun, Chaochao; Cui, Yue

    2016-01-01

    Charge balance in organic light emitting structures is essential to simultaneously achieving high brightness and high efficiency. In DC-driven organic light emitting devices (OLEDs), this is relatively straight forward. However, in the newly emerging, capacitive, field-activated AC-driven organic devices, charge balance can be a challenge. In this work we introduce the concept of gating the compensation charge in AC-driven organic devices and demonstrate that this can result in exceptional increases in device performance. To do this we replace the insulator layer in a typical field-activated organic light emitting device with a nanostructured, wide band gap semiconductor layer. This layer acts as a gate between the emitter layer and the voltage contact. Time resolved device characterization shows that, at high-frequencies (over 40 kHz), the semiconductor layer allows for charge accumulation in the forward bias, light generating part of the AC cycle and charge compensation in the negative, quiescent part of the AC cycle. Such gated AC organic devices can achieve a non-output coupled luminance of 25,900 cd/m(2) with power efficiencies that exceed both the insulator-based AC devices and OLEDs using the same emitters. This work clearly demonstrates that by realizing balanced management of charge, AC-driven organic light emitting devices may well be able to rival today's OLEDs in performance. PMID:27063414

  5. Achieving High Performance in AC-Field Driven Organic Light Sources

    NASA Astrophysics Data System (ADS)

    Xu, Junwei; Carroll, David L.; Smith, Gregory M.; Dun, Chaochao; Cui, Yue

    2016-04-01

    Charge balance in organic light emitting structures is essential to simultaneously achieving high brightness and high efficiency. In DC-driven organic light emitting devices (OLEDs), this is relatively straight forward. However, in the newly emerging, capacitive, field-activated AC-driven organic devices, charge balance can be a challenge. In this work we introduce the concept of gating the compensation charge in AC-driven organic devices and demonstrate that this can result in exceptional increases in device performance. To do this we replace the insulator layer in a typical field-activated organic light emitting device with a nanostructured, wide band gap semiconductor layer. This layer acts as a gate between the emitter layer and the voltage contact. Time resolved device characterization shows that, at high-frequencies (over 40 kHz), the semiconductor layer allows for charge accumulation in the forward bias, light generating part of the AC cycle and charge compensation in the negative, quiescent part of the AC cycle. Such gated AC organic devices can achieve a non-output coupled luminance of 25,900 cd/m2 with power efficiencies that exceed both the insulator-based AC devices and OLEDs using the same emitters. This work clearly demonstrates that by realizing balanced management of charge, AC-driven organic light emitting devices may well be able to rival today’s OLEDs in performance.

  6. Achieving high bit rate logical stochastic resonance in a bistable system by adjusting parameters

    NASA Astrophysics Data System (ADS)

    Yang, Ding-Xin; Gu, Feng-Shou; Feng, Guo-Jin; Yang, Yong-Min; Ball, Andrew

    2015-11-01

    The phenomenon of logical stochastic resonance (LSR) in a nonlinear bistable system is demonstrated by numerical simulations and experiments. However, the bit rates of the logical signals are relatively low and not suitable for practical applications. First, we examine the responses of the bistable system with fixed parameters to different bit rate logic input signals, showing that an arbitrary high bit rate LSR in a bistable system cannot be achieved. Then, a normalized transform of the LSR bistable system is introduced through a kind of variable substitution. Based on the transform, it is found that LSR for arbitrary high bit rate logic signals in a bistable system can be achieved by adjusting the parameters of the system, setting bias value and amplifying the amplitudes of logic input signals and noise properly. Finally, the desired OR and AND logic outputs to high bit rate logic inputs in a bistable system are obtained by numerical simulations. The study might provide higher feasibility of LSR in practical engineering applications. Project supported by the National Natural Science Foundation of China (Grant No. 51379526).

  7. Inactivation of Byssochlamys nivea ascospores in strawberry puree by high pressure, power ultrasound and thermal processing.

    PubMed

    Evelyn; Silva, F V M

    2015-12-01

    Byssochlamys nivea is a mold that can spoil processed fruit products and produce mycotoxins. In this work, high pressure processing (HPP, 600 MPa) and power ultrasound (24 kHz, 0.33 W/mL; TS) in combination with 75°C for the inactivation of four week old B. nivea ascospores in strawberry puree for up to 30 min was investigated and compared with 75°C thermal processing alone. TS and thermal processing can activate the mold ascospores, but HPP-75°C resulted in 2.0 log reductions after a 20 min process. For a 10 min process, HPP-75°C was better than 85°C alone in reducing B. nivea spores (1.4 vs. 0.2 log reduction), demonstrating that a lower temperature in combination with HPP is more effective for spore inactivation than heat alone at a higher temperature. The ascospore inactivation by HPP-thermal, TS and thermal processing was studied at different temperatures and modeled. Faster inactivation was achieved at higher temperatures for all the technologies tested, indicating the significant role of temperature in spore inactivation, alone or combined with other physical processes. The Weibull model described the spore inactivation by 600 MPa HPP-thermal (38, 50, 60, 75°C) and thermal (85, 90°C) processing, whereas the Lorentzian model was more appropriate for TS treatment (65, 70, 75°C). The models obtained provide a useful tool to design and predict pasteurization processes targeting B. nivea ascospores. PMID:26280285

  8. Race and Academic Achievement in Racially Diverse High Schools: Opportunity and Stratification.

    PubMed

    Muller, Chandra; Riegle-Crumb, Catherine; Schiller, Kathryn S; Wilkinson, Lindsey; Frank, Kenneth A

    2010-04-01

    BACKGROUND/CONTEXT: Brown v Board of Education fundamentally changed our nation's schools, yet we know surprisingly little about how and whether they provide equality of educational opportunity. Although substantial evidence suggests that African American and Latino students who attend these schools face fewer learning opportunities than their White counterparts, until now, it has been impossible to examine this using a representative sample because of lack of data. PURPOSE/OBJECTIVE/RESEARCH QUESTION/FOCUS OF STUDY: This study uses newly available data to investigate whether racially diverse high schools offer equality of educational opportunity to students from different racial and ethnic groups. This is examined by measuring the relative representation of minority students in advanced math classes at the beginning of high school and estimating whether and how this opportunity structure limits the level of achievement attained by African American and Latino students by the end of high school. SETTING: This study uses data from the Adolescent Health and Academic Achievement Study (AHAA) and its partner study, the National Longitudinal Study of Adolescent Health (Add Health), a stratified, nationally representative study of students in U.S. high schools first surveyed in 1994-1995. POPULATION/PARTICIPANTS/SUBJECTS: Two samples of racially diverse high schools were used in the analysis: one with African Americans, Whites, and Asians (26 schools with 3,149 students), and the other with Latinos, Whites, and Asians (22 schools with 2,775 students). RESEARCH DESIGN: Quantitative analyses first assess how high schools vary in the extent to which minority students are underrepresented in advanced sophomore math classes. Hierarchical multilevel modeling is then used to estimate whether racial-ethnic differences in representation in advanced math have an impact on African American and Latino students' achievement by the end of high school, relative to the Whites and Asians

  9. Number Sense-Based Strategies Used by High-Achieving Sixth Grade Students Who Experienced Reform Textbooks

    ERIC Educational Resources Information Center

    Alsawaie, Othman N.

    2012-01-01

    The purpose of this study was to explore strategies used by high-achieving 6th grade students in the United Arab Emirates (UAE) to solve basic arithmetic problems involving number sense. The sample for the study consisted of 15 high-achieving boys and 15 high-achieving girls in grade 6 from 2 schools in the Emirate of Abu Dhabi, UAE. Data for the…

  10. Cognitive abilities and motivational processes in high school students' science achievement and engagement

    NASA Astrophysics Data System (ADS)

    Lau, Shun

    The dissertation presents two analytic approaches, a variable-centered and person-centered approach, to investigating holistic patterns of the cognitive, motivational, and affective correlates of science achievement and engagement in a sample of 491 10th and 11th grade high-school students. Building on Snow's (1989) idea of two pathways to achievement outcomes, Study 1 adopted a variable-centered approach to examining how cognitive and motivational factors associated with the performance and commitment pathways, respectively, contributed to the prediction of achievement outcomes in science. Results of hierarchical regression analyses showed that (a) students' cognitive abilities were the strongest predictors of their performance in science as measured by standardized test scores; (b) motivational processes enhanced the predictive validity for science test scores and grades beyond the variance accounted for by ability and demography; (c) motivational processes were the strongest predictors of students' commitment to science in the form of situational engagement and anticipated choices of science-related college majors and careers; and (d) competence beliefs served as a point of contact between the performance and commitment pathways. These results are consistent with Snow's (1989) conjecture that both performance and commitment pathway-related factors are necessary for understanding the full range of person-level inputs to achievement outcomes. Study 2 adopted a person-centered approach to examining holistic organizations of psychological factors within individuals and their relations to science achievement and engagement. Four types of students characterized by unique configurations of cognitive, motivational, and affective attributes were identified in both the male and female subsamples using inverse factor analysis. Type membership was found to distinguish students in various indicators of science achievement and engagement. Two of the four types were also found

  11. Cooling history of Earth's core with high thermal conductivity

    NASA Astrophysics Data System (ADS)

    Davies, Christopher J.

    2015-10-01

    Thermal evolution models of Earth's core constrain the power available to the geodynamo process that generates the geomagnetic field, the evolution of the solid inner core and the thermal history of the overlying mantle. Recent upward revision of the thermal conductivity of liquid iron mixtures by a factor of 2-3 has drastically reduced the estimated power available to generate the present-day geomagnetic field. Moreover, this high conductivity increases the amount of heat that is conducted out of the core down the adiabatic gradient, bringing it into line with the highest estimates of present-day core-mantle boundary heat flow. These issues raise problems with the standard scenario of core cooling in which the core has remained completely well-mixed and relatively cool for the past 3.5 Ga. This paper presents cooling histories for Earth's core spanning the last 3.5 Ga to constrain the thermodynamic conditions corresponding to marginal dynamo evolution, i.e. where the ohmic dissipation remains just positive over time. The radial variation of core properties is represented by polynomials, which gives good agreement with radial profiles derived from seismological and mineralogical data and allows the governing energy and entropy equations to be solved analytically. Time-dependent evolution of liquid and solid light element concentrations, the melting curve, and gravitational energy are calculated for an Fe-O-S-Si model of core chemistry. A suite of cooling histories are presented by varying the inner core boundary density jump, thermal conductivity and amount of radiogenic heat production in the core. All models where the core remains superadiabatic predict an inner core age of ≲ 600Myr , about two times younger than estimates based on old (lower) thermal conductivity estimates, and core temperatures that exceed present estimates of the lower mantle solidus prior to the last 0.5-1.5 Ga. Allowing the top of the core to become strongly subadiabatic in recent times

  12. The effects of alcohol use on academic achievement in high school.

    PubMed

    Balsa, Ana I; Giuliano, Laura M; French, Michael T

    2011-02-01

    This paper examines the effects of alcohol use on high school students' quality of learning. We estimate fixed-effects models using data from the National Longitudinal Study of Adolescent Health. Our primary measure of academic achievement is the student's GPA abstracted from official school transcripts. We find that increases in alcohol consumption result in small yet statistically significant reductions in GPA for male students and in statistically non-significant changes for females. For females, however, higher levels of drinking result in self-reported academic difficulty. The fixed-effects results are substantially smaller than OLS estimates, underscoring the importance of addressing unobserved individual heterogeneity. PMID:21278841

  13. The Relation of High-Achieving Adolescents' Social Perceptions and Motivation to Teachers' Nominations for Advanced Programs

    ERIC Educational Resources Information Center

    Barber, Carolyn; Torney-Purta, Judith

    2008-01-01

    The discrepancies between test-based and teacher-based criteria of high achievement are well-documented for students of all ages. This study seeks to determine whether certain high school students who score high on tests of academic achievement are more likely than others to be nominated for advanced academic programs by their teachers. Using…

  14. The Differential Impact of Motivation on the Self-Regulated Strategy Use of High- and Low-Achieving College Students.

    ERIC Educational Resources Information Center

    VanZile-Tamsen, Carol; Livingston, Jennifer A.

    1999-01-01

    Low-achieving college students (N=94) evidenced less use of self-regulating strategies and a stronger relationship of self-regulated strategy use to positive motivational orientation than high-achieving students (N=49). Samples were predominantly white and female. Encouraging the use of these strategies may improve low achievers' academic…

  15. The Combined Effect of Teacher Effectiveness Characteristics on Value-Added Student Achievement in Junior High School Mathematics

    ERIC Educational Resources Information Center

    Wadleigh, Linda L.

    2013-01-01

    Student academic achievement in junior high mathematics is an ongoing mission for educational leaders. To achieve that undertaking, teacher effectiveness plays an important role. The purpose of this study was to examine the combined effects of teacher effectiveness on student achievement. The study was conducted in a suburban school district in…

  16. The effects of frequency of technology use on high school students' mathematics and science achievement

    NASA Astrophysics Data System (ADS)

    King, Michael John

    1998-11-01

    This study examined whether the frequency of technology (calculator, computer) use among a nationally representative, random, sample of U.S. public and private high school seniors significantly (p<.001) impacts mathematics and science achievement. Student survey data from NELS:88 were analyzed to determine how the frequency of technology use among approximately 11,000 high school seniors impacts mathematics and science test scores. Four data sets (calculator/mathematics, calculator/science, computer/mathematics, computer/science) were analyzed using ANCOVA, after statistically controlling for: (a) sophomore exam scores, and socio-economic status. The findings indicated that the frequency of calculator use has a significant (p<.001) impact on mathematics and science exam scores. Likewise, the frequency of computer use, has a significant (p<.001) impact on mathematics and science test scores. Mathematics students using calculators either every day or almost daily scored significantly higher than students who never or rarely used calculators. Mathematics students who employed calculators daily attained significantly greater scores than students using calculators 1-2 times per month. Mathematics students using calculators daily achieved significantly higher scores than students using calculators 1-2 times each week. Science students using calculators at any one of the following three frequencies: (a) daily, (b) almost each day, or (c) 1-2 times per week, scored significantly higher than students who never or rarely used calculators. Science students using calculators at any one of the following three rates: (a) daily, (b) almost each day, or (c) once or twice each week, attained significantly greater science exam scores when compared to students who used calculators once or twice a month. Mathematics students who never or rarely used computers achieved significantly greater test scores when compared with students who employed computers almost each day. Mathematics

  17. Thermal management in high average power pulsed compression systems

    SciTech Connect

    Wavrik, R.W.; Reed, K.W.; Harjes, H.C.; Weber, G.J.; Butler, M.; Penn, K.J.; Neau, E.L.

    1992-08-01

    High average power repetitively pulsed compression systems offer a potential source of electron beams which may be applied to sterilization of wastes, treatment of food products, and other environmental and consumer applications. At Sandia National Laboratory, the Repetitive High Energy Pulsed Power (RHEPP) program is developing a 7 stage magnetic pulse compressor driving a linear induction voltage adder with an electron beam diode load. The RHEPP machine is being design to deliver 350 kW of average power to the diode in 60 ns FWHM, 2.5 MV, 3 kJ pulses at a repetition rate of 120 Hz. In addition to the electrical design considerations, the repetition rate requires thermal management of the electrical losses. Steady state temperatures must be kept below the material degradation temperatures to maximize reliability and component life. The optimum design is a trade off between thermal management, maximizing overall electrical performance of the system, reliability, and cost effectiveness. Cooling requirements and configurations were developed for each of the subsystems of RHEPP. Finite element models that combine fluid flow and heat transfer were used to screen design concepts. The analysis includes one, two, and three dimensional heat transfer using surface heat transfer coefficients and boundary layer models. Experiments were conducted to verify the models as well as to evaluate cooling channel fabrication materials and techniques in Metglas wound cores. 10 refs.

  18. Thermal management in high average power pulsed compression systems

    SciTech Connect

    Wavrik, R.W.; Reed, K.W.; Harjes, H.C.; Weber, G.J.; Butler, M.; Penn, K.J.; Neau, E.L.

    1992-01-01

    High average power repetitively pulsed compression systems offer a potential source of electron beams which may be applied to sterilization of wastes, treatment of food products, and other environmental and consumer applications. At Sandia National Laboratory, the Repetitive High Energy Pulsed Power (RHEPP) program is developing a 7 stage magnetic pulse compressor driving a linear induction voltage adder with an electron beam diode load. The RHEPP machine is being design to deliver 350 kW of average power to the diode in 60 ns FWHM, 2.5 MV, 3 kJ pulses at a repetition rate of 120 Hz. In addition to the electrical design considerations, the repetition rate requires thermal management of the electrical losses. Steady state temperatures must be kept below the material degradation temperatures to maximize reliability and component life. The optimum design is a trade off between thermal management, maximizing overall electrical performance of the system, reliability, and cost effectiveness. Cooling requirements and configurations were developed for each of the subsystems of RHEPP. Finite element models that combine fluid flow and heat transfer were used to screen design concepts. The analysis includes one, two, and three dimensional heat transfer using surface heat transfer coefficients and boundary layer models. Experiments were conducted to verify the models as well as to evaluate cooling channel fabrication materials and techniques in Metglas wound cores. 10 refs.

  19. Thermal design studies of high-power heterojunction bipolar transistors

    NASA Astrophysics Data System (ADS)

    Gao, Guang-Bo; Wang, Ming-Zhu; Gui, Xiang; Morkoc, Hadis

    1989-05-01

    A theoretical thermoelectro-feedback model has been developed for the thermal design of high-power GaAlAs/GaAs heterojunction bipolar transistors (HBTs). The power-handling capability, thermal instability, junction temperature, and current distributions of HBTs with multiple emitter fingers have been numerically studied. The calculated results indicate that power HBTs on Si substrates (or with Si as the collector) have excellent potential power performance and reliability. The power-handling capability on Si is 3.5 and 2.7 times as large as that on GaAs and InP substrates, respectively. The peak junction temperature and temperature difference on the chip decrease in comparison to the commonly used Si homostructure power transistors with the same geometry and power dissipation. Thereby HBTs are promising for high-speed microwave and millimeter-wave applications. It has been also found that the nonuniform distribution of junction temperature and current can be greatly improved by a balasting technique that uses unequal-value emitter resistors.

  20. Corrections for Thermal Expansion in Thermal Conductivity Measurement of Insulations Using the High-Temperature Guarded Hot-Plate Method

    NASA Astrophysics Data System (ADS)

    Wu, Jiyu; Morrell, Roger

    2012-02-01

    The anticipation of recently published European product standards for industrial thermal insulation has driven improvements in high-temperature thermal conductivity measurements in an attempt to obtain overall measurement uncertainties better than 5 % ( k = 2). The two measurement issues that are focused on in this article are the effect of thermal expansion on in situ thickness measurement and on determining the metering area at high temperatures. When implementing in situ thickness measurements, it is vital to correct the thermal expansion of components in a high-temperature guarded hot plate (HTGHP). For example, in the NPL HTGHP this could cause 3.2 % measurement error for a 50 mm thick specimen at 800 °C. The thermal expansion data for nickel 201 measured by NPL are presented, and the effect of this on the metering area of NPL's heater plate (nickel 201) is discussed.